2011 Feb 25. [Epub ahead of print]
Vitro and In Vivo) Neurotoxicity Studies of Low-dose
Thimerosal Relevant to Vaccines.
Sciences, Universidade de Brasília, C.P. 04322,
Brasília, DF, Brazil, email@example.com.
is a need to interpret neurotoxic studies to help deal with
uncertainties surrounding pregnant mothers, newborns and young
children who must receive repeated doses of Thimerosal-containing
vaccines (TCVs). This review integrates information derived from
emerging experimental studies (in vitro and in vivo) of low-dose
Thimerosal (sodium ethyl mercury thiosalicylate). Major databases
(PubMed and Web-of-science) were searched for in vitro and in vivo
experimental studies that addressed the effects of low-dose
Thimerosal (or ethylmercury) on neural tissues and animal behaviour.
from studies indicates that: (a) activity of
low doses of Thimerosal against isolated human and animal brain cells
was found in all studies and is consistent with Hg neurotoxicity; (b)
the neurotoxic effect of ethylmercury has not been studied with
co-occurring adjuvant-Al in TCVs; (c) animal studies have shown that
exposure to Thimerosal-Hg can lead to accumulation of inorganic Hg in
brain, and that (d) doses relevant to TCV exposure possess the
potential to affect human neuro-development. Thimerosal at
concentrations relevant for infants' exposure (in vaccines) is toxic
to cultured human-brain cells and to laboratory animals.
The persisting use of TCV (in developing countries) is
counterintuitive to global efforts to lower Hg exposure and to ban Hg
in medical products; its continued use in TCV requires evaluation of
a sufficiently nontoxic level of ethylmercury compatible with
repeated exposure (co-occurring with adjuvant-Al) during early life.
21350943 [PubMed - as supplied by publisher]
Middle East Current Psychiatry
January 2011 - Volume 18 - Issue 1 - p
Study of some biomarkers in hair of
Eman Elsheshtawy, Department of Psychiatry Mansoura University
Hospitals, Faculty of Medicine, Mansoura, Egypt Tel: +0187455403;
fax: +26824738; e-mail: firstname.lastname@example.org
Received August 8,
is a severe developmental disorder, which involves social
withdrawal, communication deficits, and stereotypic repetitive
behavior. The possible etiologies that precipitate autism symptoms
remain controversial in many cases, but both genetic and
environmental factors have been implicated. Mercury has gained much
attention for a considerable period of time before other exacerbating
or protective factors were suggested. The aim of this study was to
investigate the relationship between autism and the level of some
metals (namely mercury, lead, and copper) or zinc as a counteracting
study recruited 32 autistic children and 32 normal controls and
all of them were subjected to KID-SCID, Childhood Autism Rating Scale
(CARS), Stanford Binet intelligence test, and biochemical analysis of
hair samples for the level of mercury, copper, lead and zinc.
were highly significant differences between the level of these
substances in the hair of children with autism compared with
controls, positive correlation of CARS score with both mercury and
while intelligence quotient has significant negative correlation with
the level of lead in the hair. The level of zinc does not correlate
with either CARS score or intelligence quotient.
preliminary results suggest a complementary role for the studied
elements in the pathogenesis of autistic disorder, which should be
considered in the management plane.
after intermittent neonatal
administration of thimerosal.
the Nervous System, Institute of
Psychiatry and Neurology, ul. Sobieskiego 9, Warsaw, Poland.
preservative to some vaccines, is a
suspected iatrogenic factor, possibly contributing to paediatric
neurodevelopmental disorders including autism. We examined the
effects of early postnatal administration of thimerosal (four i.m.
injections, 12 or 240 μg THIM-Hg/kg, on postnatal days 7, 9, 11 and
15) on brain pathology in Wistar rats. Numerous neuropathological
changes were observed in young adult rats which were treated
postnatally with thimerosal. They included: ischaemic degeneration of
neurons and "dark" neurons in the prefrontal and temporal
cortex, the hippocampus and the cerebellum, pathological changes of
the blood vessels in the temporal cortex, diminished synaptophysin
reaction in the hippocampus, atrophy of astroglia in the hippocampus
and cerebellum, and positive caspase-3 reaction in Bergmann
of thimerosal, at doses
equivalent to those used in infant vaccines or higher, in developing
rat brain, suggesting likely involvement of this mercurial in
21225508 [PubMed - in process]Free Article
J Immunopathol Pharmacol.
thimerosal-induced VEGF release
from human mast cells.
Pharmacology and Experimental Therapeutics, Tufts University School
of Medicine and Tufts Medical Center, Boston.
but is also used as preservative
in vaccines as thimerosal containing ethyl mercury covalently linked
We recently reported that mercury choloride (HgCl2) can stimulate
human mast cells to release vascular endothelial growth factor
(VEGF), which is also vasoactive and pro-inflammatory. Here we show
that thimerosal induces significant VEGF release from human leukemic
cultured LAD2 mast cells (at 1 microM 326∓12
pg/106 cells and 335.5±12 pg/106 cells at 10 microM) compared to
control cells (242±21 pg/106 cells, n=5, p less than 0.05); this
effect is weaker than that induced by HgCl2 at 10 microM (448±14
pg/106 cells) (n=3, p less than 0.05). In view of this finding, we
hypothesize that the thiosalicylate component of thimerosal may have
an inhibitory effect on VEGF release. Thimerosal (10 microM) added
together with the peptide Substance P (SP) at 2 microM, used as a
positive control, reduced VEGF release by 90 percent. Methyl
thiosalicylate (1 or 10 microM) added with either SP or HgCl2 (10
microM) inhibited VEGF release by 100 percent, while sodium
salicylate or ibuprofen had no effect. Pretreatment for 10 min with
the flavonoid luteolin (0.1 mM) before HgCl2 or thimerosal compeletly
blocked their effect. Luteolin and methyl thiosalicylate may be
useful in preventing mercury-induced toxicity.
21244751 [PubMed - in process]
Neurobiol Exp (Wars).
growth and opioid ligand binding in
rhesus macaque infants: A pilot study.
of Pittsburgh School of
Medicine, Pittsburgh, PA, USA. email@example.com
longitudinal, case-control pilot study examined amygdala growth in
rhesus macaque infants receiving the complete US childhood vaccine
schedule (1994-1999). Longitudinal structural and functional
neuroimaging was undertaken to examine central effects of the vaccine
regimen on the developing brain. Vaccine-exposed and saline-injected
control infants underwent MRI and PET imaging at approximately 4 and
6 months of age, representing two specific timeframes within the
vaccination schedule. Volumetric analyses showed that exposed animals
did not undergo the maturational changes over time in amygdala volume
that was observed in unexposed animals. After controlling for left
amygdala volume, the binding of the opioid antagonist
[(11)C]diprenorphine (DPN) in exposed animals remained relatively
constant over time, compared with unexposed animals, in which a
significant decrease in [(11)C]DPN binding occurred. These
in amygdala volume and the
binding capacity of [(11)C]DPN in the amygdala was significantly
altered in infant macaques receiving the vaccine schedule.
The macaque infant is a relevant animal model in which to investigate
specific environmental exposures and structural/functional
neuroimaging during neurodevelopment.
20628439 [PubMed - indexed for MEDLINE]Free Article
2010 Nov;84(11):891-6. Epub 2010 Apr 13.
in rat tissues following
administration of thimerosal or methylmercury.
de Análises Clínicas, Toxicológicas e
Avenida do Café, s/n, Monte Alegre, Ribeirão Preto, SP
toxic forms of Hg, with a considerable range
of harmful effects on humans. Sodium ethyl mercury thiosalicylate,
thimerosal (TM) is an ethylmercury (Et-Hg)-containing preservative
that has been used in manufacturing vaccines in many countries.
Whereas the behavior of Met-Hg in humans is relatively well known,
that of ethylmercury (Et-Hg) is poorly understood. The present study
describes the distribution of mercury as (-methyl, -ethyl and
inorganic mercury) in rat tissues (brain, heart, kidney and liver)
and blood following administration of TM or Met-Hg. Animals received
one dose/day of Met-Hg or TM by gavage (0.5 mg Hg/kg).
Blood samples were collected after 6, 12, 24, 48, 96 and 120 h
of exposure. After 5 days, the animals were killed, and their
tissues were collected. Total blood mercury (THg) levels were
determined by ICP-MS, and methylmercury (Met-Hg), ethylmercury
(Et-Hg) and inorganic mercury (Ino-Hg) levels were determined by
speciation analysis with LC-ICP-MS. Mercury remains longer in the
blood of rats treated with Met-Hg compared to that of TM-exposed
rats. Moreover, after 48 h of the TM treatment, most of the Hg
found in blood was inorganic. Of the total mercury found in the brain
after TM exposure, 63% was in the form of Ino-Hg, with 13.5% as Et-Hg
and 23.7% as Met-Hg. In
blood following TM treatment was
predominantly found as Ino-Hg, but a considerable amount of Et-Hg was
also found in the liver and brain. Taken together, our data
demonstrated that the toxicokinetics of TM is completely different
from that of Met-Hg. Thus, Met-Hg is not an appropriate reference for
assessing the risk from exposure to TM-derived Hg. It also adds new
data for further studies in the evaluation of TM toxicity.
20386881 [PubMed - indexed for MEDLINE]
other words, it is not settled….
2010 Apr;26(2):143-52. Epub 2009 Apr 9.
and cerebrum with low-dose
Higashi-osaka, Osaka, Japan.
used worldwide as a vaccine
preservative. We previously observed that the mercury concentration
in mouse brains did not increase with the clinical dose of thimerosal
injection, but the concentration increased in the brain after the
injection of thimerosal with lipopolysaccharide, even if a low dose
of thimerosal was administered. Thimerosal may penetrate the brain,
but is undetectable when a clinical dose of thimerosal is injected;
therefore, the induction of metallothionein (MT) messenger RNA (mRNA)
and protein was observed in the cerebellum and cerebrum of mice after
thimerosal injection, as MT is an inducible protein. MT-1 mRNA was
expressed at 6 and 9 h in both the cerebrum and cerebellum, but MT-1
mRNA expression in the cerebellum was three times higher than that in
the cerebrum after the injection of 12 microg/kg thimerosal. MT-2
mRNA was not expressed until 24 h in both organs. MT-3 mRNA was
expressed in the cerebellum from 6 to 15 h after the injection, but
not in the cerebrum until 24 h. MT-1 and MT-3 mRNAs were expressed in
the cerebellum in a dose-dependent manner. Furthermore, MT-1 protein
was detected from 6 to 72 h in the cerebellum after 12 microg/kg of
thimerosal was injected and peaked at 10 h. MT-2 was detected in the
cerebellum only at 10 h. In the cerebrum, little MT-1 protein was
detected at 10 and 24 h, and there were no peaks of MT-2 protein in
the cerebrum. In conclusion, MT-1 and MT-3 mRNAs but not MT-2 mRNA
are easily expressed in the cerebellum rather than in the cerebrum by
the injection of low-dose thimerosal. It is thought that the
cerebellum is a sensitive organ against thimerosal. As
findings, in combination with the brain
pathology observed in patients diagnosed with autism, the present
study helps to support the possible biological plausibility for how
low-dose exposure to mercury from thimerosal-containing vaccines may
be associated with autism.
19357975 [PubMed - indexed for MEDLINE]
2010 Mar 15;243(3):283-91. Epub 2009 Sep 2.
Clinical and Experimental
Medicine, Linköping University, SE-58185 Linköping, Sweden.
(Hg) exposure from dental amalgam fillings and thimerosal in vaccines
is not a major health hazard, but adverse health effects cannot be
ruled out in a small and more susceptible part of the exposed
population. Individual differences in toxicokinetics may explain
susceptibility to mercury. Inbred, H-2-congenic A.SW and B10.S mice
and their F1- and F2-hybrids were given HgCl2 with 2.0 mg Hg/L
drinking water and traces of (203)Hg. Whole-body retention (WBR) was
monitored until steady state after 5 weeks, when the organ Hg content
was assessed. Despite similar Hg intake, A.SW males attained a 20-30%
significantly higher WBR and 2- to 5-fold higher total renal Hg
retention/concentration than A.SW females and B10.S mice. A selective
renal Hg accumulation but of lower magnitude was seen also in B10.S
males compared with females. Differences in WBR and organ Hg
accumulation are therefore regulated by non-H-2 genes and gender.
Lymph nodes lacked the strain- and gender-dependent Hg accumulation
profile of kidney, liver and spleen. After 15 days without Hg A.SW
mice showed a 4-fold higher WBR and liver Hg concentration, but
11-fold higher renal Hg concentration, showing the key role for the
kidneys in explaining the slower Hg elimination in A.SW mice. The
trait causing higher mercury accumulation was not dominantly
inherited in the F1 hybrids. F2 mice showed a large inter-individual
variation in Hg accumulation, showing that multiple genetic factors
influence the Hg toxicokinetics in the mouse. The
therefore show a large
variation in mercury toxicokinetics.
Elsevier Inc. All rights reserved.
19732784 [PubMed - indexed for MEDLINE]
2010 Nov 11;411(21-22):1580-6. Epub 2010 Jul 16.
epidemiological studies of young children exposed to
thimerosal in vaccines.
04322, Universidade de Brasilia, 70919-970 Brasilia, DF, Brazil.
compare epidemiological studies dealing with neurological issues
(compatible with Hg toxicity) linked to exposing newborns and infants
to intramuscular doses of preservative-Hg resulting from vaccination
with thimerosal-containing vaccines (TCV).
databases were searched for studies that addressed neurodevelopment
outcomes other than autism. Eight studies were identified and
the studies done in the USA, the UK, and Italy is
important in understanding the complex interplay of variables but
insufficient to establish non-toxicity for infants and young children
still receiving TCV: a) there is ambiguity in some studies reporting
neurodevelopment outcomes that seem to depend on confounding
variables; b) the risk of neurotoxicity due to low doses of
thimerosal is plausible at least for susceptible infants;
c) there is a need to address these issues in less developed
countries still using TCV in pregnant mothers, newborns, and young
the use of TCV is still inevitable in many countries, this increases
the need to protect vulnerable infants and promote actions that
strengthen neurodevelopment. Developing countries should intensify
campaigns that include breastfeeding among efforts to help prime the
central nervous system to tolerate exposure to neurotoxic substances,
Elsevier B.V. All rights reserved.
20638374 [PubMed - indexed for MEDLINE]
Neurobiol Exp (Wars).
higher levels of hair mercury in autistic children than in
and Physiology of the Nervous System, Institute of
Psychiatry and Neurology, Warsaw, Poland. firstname.lastname@example.org
association between autism and early life exposure to mercury is a
hotly debated issue. In this study, 91 autistic Polish children, male
and female, 3-4 and 7-9 years old, were compared to 75 age- and
sex-matched healthy children with respect to: demographic, perinatal,
clinical and developmental measures, parental age, birth order,
morphometric measures, vaccination history, and hair mercury content.
In demographic and perinatal measures there were no consistent
differences between the autistic and control groups. Autistic
a significantly greater prevalence of adverse reactions
after vaccinations and abnormal development than controls. Between 45
and 80% of autistic children experienced developmental regress.
Autistic children significantly differed from healthy peers in the
concentrations of mercury in hair: younger autistics had lower
levels, while older - higher levels than their respective controls.
The results suggest that autistic children differ from healthy
children in metabolism of mercury, which seems to change with age.
20628443 [PubMed - indexed for MEDLINE]Free Article
2010 Jan 15;80(3):1158-63.
mercury determination in blood by using liquid
chromatography with inductively coupled plasma mass spectrometry and
a fast sample preparation procedure.
Oliveira Souza VC,
e Essencialidade de Metais, Faculdade de Ciências
Farmacêuticas de Ribeirão Preto, Universidade de
Ribeirão Preto, SP, Brazil.
to differentiate chemical species of mercury in
clinical specimens, there are a limited number of methods for this
purpose. Then, this paper describes a simple method for the
determination of methylmercury and inorganic mercury in blood by
using liquid chromatography with inductively coupled mass
spectrometry (LC-ICP-MS) and a fast sample preparation procedure.
Prior to analysis, blood (250microL) is accurately weighed into 15-mL
conical tubes. Then, an extractant solution containing
mercaptoethanol, l-cysteine and HCl was added to the samples
following sonication for 15min. Quantitative mercury extraction was
achieved with the proposed procedure. Separation of mercury species
was accomplished in less than 5min on a C18 reverse-phase column with
a mobile phase containing 0.05% (v/v) mercaptoethanol, 0.4% (m/v)
l-cysteine, 0.06molL(-1) ammonium acetate and 5% (v/v) methanol. The
method detection limits were found to be 0.25microgL(-1) and
0.1microgL(-1) for inorganic mercury and methylmercury, respectively.
Method accuracy is traceable to Standard Reference Material (SRM) 966
Toxic Metals in Bovine Blood from the National Institute of Standards
and Technology (NIST). The proposed method was also applied to the
speciation of mercury in blood samples collected from fish-eating
communities and from rats exposed to thimerosal. With the proposed
method there is a considerable reduction of the time of sample
preparation prior to speciation of Hg by LC-ICP-MS. Finally,
application of the proposed method, we demonstrated an
interesting in vivo ethylmercury conversion to inorganic mercury.
20006068 [PubMed - indexed for MEDLINE]
2010 Jul;18(1):59-68. Epub 2009 Sep 16.
neuropathological conditions relevant to ethylmercury exposure?
Vanderbilt University Medical Center, Nashville, TN
37232, USA. email@example.com
compounds are among the environmentally ubiquitous
substances most toxic to both wildlife and humans. Once released into
the environment from both natural and anthropogenic sources, mercury
exists mainly as three different molecular species: elemental,
inorganic, and organic. Potential health risks have been reported
from exposure to all forms; however, of particular concern for human
exposure relate to the potent neurotoxic effects of methylmercury
(MeHg), especially for the developing nervous system. The general
population is primarily exposed to MeHg by seafood consumption. In
addition, some pharmaceuticals, including vaccines, have been, and
some continue to be, a ubiquitous source of exposure to mercurials. A
significant controversy has been whether the vaccine preservative
ethylmercury thiosalicylate, commonly known as thimerosal, could
cause the development of autism. In this review, we have discussed
the hypothesis that exposure to thimerosal during childhood may be a
primary cause of autism. The
that there are no reliable data indicating that
administration of vaccines containing thimerosal is a primary cause
of autism. However, one cannot rule out the possibility that the
individual gene profile and/or gene-environment interactions may play
a role in modulating the response to acquired risk by modifying the
19756911 [PubMed - indexed for MEDLINE]
Environ Sci (China).
phenyl-, ethylmercury and mercurychlorid on immune cells
of harbor seals (Phoca vitulina).
Research Center Institute for Coastal Research, Max-Planck-Strasse 1,
21502 Geesthacht, Germany. firstname.lastname@example.org
present in the marine environment as a natural metal often
enhanced through human activities. Depending on its chemical form, Hg
can cause a wide range of immunotoxic effects. In this study, the
influence of methyl-, ethyl- and phenylmercury as well as
mercurychloride on immune functions was evaluated. Two parameters of
cellular immunity, proliferation and mRNA cytokine expression of
interleukin-2, -4, and transforming growth factor beta, were
investigated in harbor seal lymphocytes after in vitro exposure to Hg
Hg compounds had a suppressive effect on proliferation,
differences between juvenile and adult seals were found. Lymphocytes
from juveniles showed a higher susceptibility to the toxic effect
compared to lymphocytes from adults. Furthermore, the degree of
inhibition of proliferation varied among the four Hg compounds. The
organic compounds seem to be more immunotoxic than the inorganic
Finally, for the cytokine expression of methylmercury-incubated
lymphocytes, time-dependent changes were observed, but no
dose-dependency was found. Marine mammals of the North Sea are
burdened with Hg, and lymphocytes of harbor seals may be functionally
impaired by this metal. The present in vitro study provides baseline
information for future studies on the immunotoxic effects of Hg on
cellular immunity of harbor seals.
20131603 [PubMed - indexed for MEDLINE]
2009 Nov 18;2:199.
usefulness of chelation therapy for the remission of symptoms caused
by previous treatment with mercury-containing pharmaceuticals: a case
umana e Scienze Biomediche-Città Studi,
Milano, Via Mangiagalli, 31 20133, Milan, Italy. email@example.com
great deal of data regarding the toxicology of mercury has been
recently reported. Although the most common human exposures to
mercury are currently mercury vapour from amalgam tooth fillings,
methylmercury from seafood and ethylmercury as a preservative in
vaccines, in the past mercury compounds have been used in the
treatment of syphilis.
intoxication was found in a 67 year-old Italian man affected by
neurological symptoms of apparently unknown origin. The patient
developed syphilis forty years ago and then underwent therapy with
mercurials to treat his chronic bacterial infection. We treated the
patient with disodium edetate chelation therapy. Six months after the
beginning of the therapy, the patient's neurological symptoms began
to decrease, and were completely cured after two years of therapy.
case supports the use of chelation therapy with disodium edetate to
remove damages caused by mercury intoxication.
know what kind of mercury, however. It may not have been
2009 Aug;23(8):2374-83. Epub 2009 Mar 23.
glutathione redox imbalance in lymphoblastoid cells
derived from children with autism.
University of Arkansas for Medical Sciences, Arkansas
Children's Hospital Research Institute, 1120 Marshall St., Little
Rock, AR 72202, USA. firstname.lastname@example.org
metabolic phenotype of autism has been relatively unexplored
despite the fact that metabolic abnormalities have been implicated in
the pathophysiology of several other neurobehavioral disorders.
Plasma biomarkers of oxidative stress have been reported in autistic
children; however, intracellular redox status has not yet been
evaluated. Lymphoblastoid cells (LCLs) derived from autistic children
and unaffected controls were used to assess relative concentrations
of reduced glutathione (GSH) and oxidized disulfide glutathione
(GSSG) in cell extracts and isolated mitochondria as a measure of
intracellular redox capacity. The results indicated that the GSH/GSSG
redox ratio was decreased and percentage oxidized glutathione
increased in both cytosol and mitochondria in the autism LCLs.
oxidative stress via the sulfhydryl reagent thimerosal
resulted in a greater decrease in the GSH/GSSG ratio and increase in
free radical generation in autism compared to control cells.
Acute exposure to physiological levels of nitric oxide decreased
mitochondrial membrane potential to a greater extent in the autism
LCLs, although GSH/GSSG and ATP concentrations were similarly
decreased in both cell lines. These
that the autism LCLs exhibit a reduced glutathione
reserve capacity in both cytosol and mitochondria that may compromise
antioxidant defense and detoxification capacity under prooxidant
19307255 [PubMed - indexed for MEDLINE]PMCID: PMC2717775Free PMC
2009 Oct;22(5):697-700. Epub 2009 Feb 11.
toxic biometals destroying your children's future?
and mercury have been linked to autism, attention
deficit disorder, mental retardation and death of children. Mercury
found in many vaccines and flu shots contributes
significantly to these problems. Decomposition of the thimerosal can
produce more toxic compounds, either methylethylmercury or
diethylmercury, in the body. These compounds have a toxicity level
similar to dimethylmercury.
Within the human body, a mitochondrial disorder may release the more
toxic form of mercury internally. Young
pregnant women must minimize internal exposure to the
vaccines and flu shots containing mercury.
19205900 [PubMed - indexed for MEDLINE]
2009 Mar;61(2):133-6. Epub 2008 Sep 3.
and Laboratory Medicine and Pathobiology, University of
Toronto, Ontario, Canada. email@example.com
recent report shows a correlation of the historical use of thimerosal
in therapeutic immunizations with the subsequent development of
autism; however, this association remains controversial. Autism
occurs approximately four times more frequently in males compared to
females; thus, studies of thimerosal toxicity should take into
consideration gender-selective effects. The present study was
originally undertaken to determine the maximum tolerated dose (MTD)
of thimersosal in male and female CD1 mice. However, during the
limited MTD studies, it became apparent that thimerosal has a
differential MTD that depends on whether the mouse is male or female.
At doses of 38.4-76.8mg/kg using 10% DMSO as diluent, seven of seven
male mice compared to zero of seven female mice tested succumbed to
thimerosal. Although the thimerosal levels used were very high, as we
were originally only trying to determine MTD, it was completely
unexpected to observe a difference of the MTD between male and female
although not directly addressing the controversy
surrounding thimerosal and autism, and still preliminary due to small
numbers of mice examined, provide, nevertheless, the first report of
gender-selective toxicity of thimerosal and indicate that any future
studies of thimerosal toxicity should take into consideration
18771903 [PubMed - indexed for MEDLINE]
2009 Sep;23(6):1092-9. Epub 2009 Jun 2.
thimerosal in rat thymocytes:
intracellular Zn2+ release induced by oxidative stress.
Integrated Arts and Sciences, The
University of Tokushima, Tokushima 770-8502, Japan.
products, was recently reported to increase intracellular Zn(2+)
toxicity of TMR remain because of
physiological and pathological roles of Zn(2+).
To reveal the property of TMR-induced increase in intracellular
Zn(2+) concentration, the effect of TMR on FluoZin-3 fluorescence, an
indicator of intracellular Zn(2+), of rat thymocytes was examined.
TMR at concentrations ranging from 0.3 microM to 10 microM increased
the intensity of FluoZin-3 fluorescence in a concentration-dependent
manner under external Ca(2+)- and Zn(2+)-free condition. The
threshold concentration was 0.3-1 microM. The increase in the
intensity was significant when TMR concentration was 1 microM or
more. N,N,N',N'-Tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a
chelator for intracellular Zn(2+), completely attenuated the
TMR-induced augmentation of FluoZin-3 fluorescence. Hydrogen peroxide
(H(2)O(2)) and N-ethylmaleimide, reducing cellular thiol content,
significantly increased FluoZin-3 fluorescence intensity and
decreased 5-chloromethylfluorescein (5-CMF) fluorescence intensity,
an indicator for cellular thiol. The correlation coefficient between
TMR-induced augmentation of FluoZin-3 fluorescence and attenuation of
5-CMF fluorescence was -0.882. TMR also attenuated the 5-CMF
fluorescence in the presence of TPEN. Simultaneous application of
H(2)O(2) and TMR synergistically augmented the FluoZin-3
intracellular Zn(2+) concentration
via decreasing cellular thiol content.
19497362 [PubMed - indexed for MEDLINE]
Ocul Pharmacol Ther.
corneal and conjunctival
Center, New York, NY
10029-6574, USA. firstname.lastname@example.org
all eye drops contain preservatives to decrease contamination.
Nonpreservatives such as disodium-ethylene diamine tetra-acetate
(EDTA) and phosphate-buffered saline are also regularly added as
buffering agents. These components can add to the toxicity of eye
drops and cause ocular surface disease. To evaluate the potential
toxicity of these common components and their comparative effects on
the ocular surface, a tissue culture model utilizing immortalized
corneal and conjunctival epithelial cells was utilized.
human conjunctival and corneal epithelial cells were grown. At
confluency, medium was replaced with 100 microL of varying
concentrations of preservatives: benzalkonium chloride (BAK), methyl
paraben (MP), sodium perborate (SP), chlorobutanol (Cbl), and
stabilized thimerosal (Thi); varying concentrations of buffer: EDTA;
media (viable control); and formalin (dead control). After 1 h,
solutions were replaced with 150 microL of MTT
(3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazonium bromide).
After 4 h, solutions decanted, 100 microL of acid isopropanol added,
and the optical density determined at 572 nm to evaluate cell
seen with all preservatives.
Depending upon concentration, BAK exhibited from 56% to 89% toxicity.
In comparison, Cbl exhibited from 50% to 86%, MP from 30% to 76%, SP
from 23% to 59%, and Thi
EDTA with minimal toxicity (from 6% to 59%) was indistinguishable
at the most commonly used
concentrations: Thi (0.0025%) > BAK (0.025%) > Cbl (0.25%) >
MP (0.01%) > SP (0.0025%) approximately EDTA (0.01%). Even at low
concentration, these agents will cause some degree of ocular tissue
19284328 [PubMed - indexed for MEDLINE]PMCID: PMC2958436Free PMC
Louisville, Kentucky 40202,
cycling of mercury results in the presence of mercury salts in the
environment. The well-established negative effects of mercury on the
immune system led us to the study whether natural immunomodulator
glucan can overcome the immunosuppressive effects of mercury. Two
mercury acetate, were administered
in a dose of 2-8 mg/L of drinking water to mice.
profound suppression of both cellular
(phagocytosis, natural killer cell activity, mitogen-induced
proliferation, and expression of CD markers) and humoral (antibody
formation and secretion of interleukin-6, interleukin-12, and
The mice were then fed with a diet containing a standard dose of
glucan. Our results showed that simultaneous treatment with mercury
and glucan resulted in significantly lower immunotoxic effects of
mercury, which suggests that glucans can be successfully used as a
natural remedy of low-level exposure to mercury.
19857075 [PubMed - indexed for MEDLINE]
what, if any, cell damage occurs when injected.
Salusmed Medical Center,
Wieslistrasse 34, CH - 8267 Berlingen, Switzerland. email@example.com
hypothesized to be the main
cause of the Kawasaki's Disease but the etiology is unknown.
Medical literature, epidemiological findings, and some case reports
have suggested that mercury may play a pathogenic role. Several
patients with Kawasaki's Disease have presented with elevated urine
mercury levels compared to matched controls. Most symptoms and
diagnostic criteria which are seen in children with acrodynia, known
to be caused by mercury, are similar to those seen in Kawasaki's
Disease. Genetic depletion of glutathione S-transferase , a
susceptibility marker for Kawasaki's Disease, is known to be also a
risk factor for acrodynia and may also increase susceptibility to
mercury . Coinciding
of thimerosal (49.6% ethyl
mercury) in vaccines, routinely given to infants in the U.S. by 6
months of age (from 75microg to 187.5microg), the rates of Kawasaki's
Disease increased ten times, and, later (1985-1997), by 20 times.
Since 1990 88 cases of patients developing Kawasaki's Disease some
days after vaccination have been reported to the Centers of Disease
Control (CDC) including 19% manifesting symptoms the same day.
The presented pathogenetic model may lead to new preventive- and
therapeutic strategies for Kawasaki's disease.
19075648 [PubMed - indexed for MEDLINE]
2008 Jun;22(4):927-34. Epub 2008 Feb 1.
lymphocytes with and without
metabolic activation sister chromatid exchange analysis proliferation
index and mitotic index.
University, Faculty of Science and Letters, Department of Biology,
33343 Mersin, Turkey.
of ethyl mercury that has been used
for years as a preservative in many infant vaccines and in flu
vaccines. Thimerosal is an organic mercurial compound used as a
preservative in biomedical preparations. In this study, we evaluated
the genotoxic effect of thimerosal in cultured human peripheral blood
lymphocytes using sister chromatid exchange analysis in culture
conditions with and without S9 metabolic activation. This study is
the first report investigating the genotoxic effects of thimerosal in
cultured human peripheral blood lymphocyte cells using sister
chromatid exchange analysis. An analysis of variance test (ANOVA) was
performed to evaluate the results. Significant induction of sister
chromatid exchanges was seen at concentrations between 0.2 and 0.6
microg/ml of thimerosal compared with negative control. A significant
decrease (p<0.001) in mitotic index (MI) and proliferation index
(PRI) as well as an increase in SCE frequency (p<0.001) was
observed compared with control cultures. Our
cytotoxic effect of TH in cultured
human peripheral blood lymphocytes at tested doses in cultures
with/without S9 fraction.
18321677 [PubMed - indexed for MEDLINE]
2008 Feb;21(2):483-93. Epub 2008 Jan 16.
thimerosal and inhibition of DNA
topoisomerase II alpha.
50 Sifton Road, Winnipeg,
Manitoba, R3T 2N2, Canada.
that is widely used as a preservative
in vaccines and other solution formulations. The use of thimerosal
has caused concern about its ability to cause neurological
abnormalities due to mercury accumulation during a normal schedule of
childhood vaccinations. While the chemistry and the biological
effects of methylmercury have been well-studied, those of thimerosal
have not. Thimerosal reacted rapidly with cysteine, GSH, human serum
albumin, and single-stranded DNA to form ethylmercury adducts that
were detectable by mass spectrometry. These results indicated that
thimerosal would be quickly metabolized in vivo because of its
reactions with protein and nonprotein thiols. Thimerosal also
potently inhibited the decatenation activity of DNA topoisomerase II
alpha, likely through reaction with critical free cysteine thiol
groups. Thimerosal, however, did not act as a topoisomerase II poison
and the lack of cross-resistance with a K562 cell line with a
decreased level of topoisomerase II alpha (K/VP.5 cells) suggested
that inhibition of topoisomerase II alpha was not a significant
mechanism for the inhibition of cell growth. Depletion of
intracellular GSH with buthionine sulfoximine treatment greatly
increased the K562 cell growth inhibitory effects of thimerosal,
which showed that intracellular glutathione had a major role in
protecting cells from thimerosal. Pretreatment of thimerosal with
glutathione did not, however, change its K562 cell growth inhibitory
effects, a result consistent with the rapid exchange of the
ethylmercury adduct among various thiol-containing cellular
in K562 cells were consistent with a
rapid induction of apoptosis. In conclusion, these studies have
elucidated some of the chemistry and biological activities of the
interaction of thimerosal with topoisomerase II alpha and protein and
nonprotein thiols and with DNA.
18197631 [PubMed - indexed for MEDLINE]
is “programmed cell death”.
Ther Health Med.
possible central mechanism in autism spectrum disorders, part 1.
autism spectrum disorders (ASD) are a group of related
neurodevelopmental disorders that have been increasing in incidence
since the 1980s. Despite a considerable amount of data being
collected from cases, a central mechanism has not been offered. A
of ASD cases discloses a number of events that adhere
to an immunoexcitotoxic mechanism. This mechanism explains the link
between excessive vaccination, use of aluminum and ethylmercury as
vaccine adjuvants, food allergies, gut dysbiosis, and abnormal
formation of the developing brain.
It has now been shown that chronic microglial activation is present
in autistic brains from age 5 years to age 44 years. A considerable
amount of evidence, both experimental and clinical, indicates that
repeated microglial activation can initiate priming of the microglia
and that subsequent stimulation can produce an exaggerated microglial
response that can be prolonged. It is also known that one phenotypic
form of microglia activation can result in an outpouring of
neurotoxic levels of the excitotoxins, glutamate and quinolinic acid.
Studies have shown that careful control of brain glutamate levels is
essential to brain pathway development and that excesses can result
in arrest of neural migration, as well as dendritic and synaptic
loss. It has also been shown that certain cytokines, such as
TNF-alpha, can, via its receptor, interact with glutamate receptors
to enhance the neurotoxic reaction. To describe this interaction I
have coined the term immunoexcitotoxicity, which is described in this
19043938 [PubMed - indexed for MEDLINE]
2008 Aug 15;271(1-2):110-8. Epub 2008 May 15.
infants and neurodevelopmental disorders: an assessment
of computerized medical records in the Vaccine Safety Datalink.
George Washington University School of Public Health and Health
Services, Department of Epidemiology and Biostatistics, United
study evaluated possible associations between neurodevelopmental
disorders (NDs) and exposure to mercury (Hg) from
Thimerosal-containing vaccines (TCVs) by examining the automated
Vaccine Safety Datalink (VSD). A total of 278,624 subjects were
identified in birth cohorts from 1990-1996 that had received their
first oral polio vaccination by 3 months of age in the VSD. The birth
cohort prevalence rate of medically diagnosed International
Classification of Disease, 9th revision (ICD-9) specific NDs and
control outcomes were calculated. Exposures to Hg from TCVs were
calculated by birth cohort for specific exposure windows from birth-7
months and birth-13 months of age. Poisson regression analysis was
used to model the association between the prevalence of outcomes and
Hg doses from TCVs. Consistent
rate ratios were observed for autism, autism
spectrum disorders, tics, attention deficit disorder, and emotional
disturbances with Hg exposure from TCVs. By contrast, none of the
control outcomes had significantly increased rate ratios with Hg
exposure from TCVs.
Routine childhood vaccination should be continued to help reduce the
morbidity and mortality associated with infectious diseases, but
efforts should be undertaken to remove Hg from vaccines. Additional
studies should be conducted to further evaluate the relationship
between Hg exposure and NDs.
18482737 [PubMed - indexed for MEDLINE]
2008 May;29(3):532-45. Epub 2008 Feb 23.
susceptibilities of autism.
De Water J,
of Veterinary Medicine, University of California, Davis, CA 95616,
on research approaches that are aimed at understanding
common patterns of immunological and neurological dysfunction
contributing to neurodevelopmental disorders such as autism and ADHD.
The session focused on genetic, epigenetic, and environmental factors
that might act in concert to influence autism risk, severity and
co-morbidities, and immunological and neurobiological targets as
etiologic contributors. The
of children at risk of autism may be therefore
especially susceptible to psychological stressors, exposure to
chemical triggers, and infectious agents.
Identifying early biomarkers of risk provides tangible approaches
toward designing studies in animals and humans that yield a better
understanding of environmental risk factors, and can help identify
rational intervention strategies to mitigate these risks.
18394707 [PubMed - indexed for MEDLINE]PMCID: PMC2475601Free PMC
Section VII – “Examination of Thimerosal Effects in neonatal
SJL/J Mice at Vaccination-Associated Exposure Levels”
Toxicol Environ Health A.
on murine and human kidney
Center, University of California,
Davis, California, USA. firstname.lastname@example.org
inner medullary collecting duct cells (mIMCD3) and human embryonic
kidney cells (HEK293) were used for cytoscreening of thimerosal and
mercury chloride (HgCl2). Thimerosal and HgCl2 acted in a
concentration-dependent manner. In mIMCD3 cells the 24-h LC50 values
for thimerosal, thiosalicylic acid, 2,2-dithiosalicylic acid, and
2-sulfobenzoic acid were 2.9, 2200, >1000, and >10,000 microM,
respectively. The 24-h LC50 value for HgCl2 in mIMCD3 cells was 40
microM. In HEK293 cells, the 24-h LC50 value for thimerosal was 9.5
cytotoxicity produced by thimerosal
on renal cells with respect to similar compounds without Hg may be
related to this metal content.
The present study also establishes mIMCD3 cells as a valuable model
for evaluation of cytotoxicity of nephrotoxic compounds.
18049999 [PubMed - indexed for MEDLINE]
2007 Nov;100(1):109-17. Epub 2007 Aug 13.
cancer cells: activation of p38 MAP
kinase and caspase-3 pathways without involvement of [Ca2+]i
Hospital, Kaohsiung, Taiwan
some vaccines. The effect of
thimerosal on human gastric cancer cells is unknown. This
human gastric cancer cells (SCM1),
thimerosal reduced cell viability in a concentration- and
Thimerosal caused apoptosis as assessed by propidium iodide-stained
cells and caspase-3 activation. Although immunoblotting data revealed
that thimerosal could activate the phosphorylation of extracellular
signal-regulated kinase, c-Jun NH2-terminal protein kinase, and p38
mitogen-activated protein kinase (p38 MAPK), only SB203580 (a p38
MAPK inhibitor) partially prevented cells from apoptosis. Thimerosal
also induced [Ca2+](i) increases via Ca2+ influx from the
extracellular space. However, pretreatment with
(bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetate)/AM, a Ca2+
chelator, to prevent thimerosal-induced [Ca2+](i) increases did not
protect cells from death. The
cells, thimerosal caused
Ca2+-independent apoptosis via phosphorylating p38 MAPK resulting in
17698513 [PubMed - indexed for MEDLINE]Free Article
2007 Feb 28;231(1):40-57. Epub 2006 Nov 25.
death and cytotoxic effects in YAC-1 lymphoma cells following
exposure to various forms of mercury.
College of Veterinary
Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon SK
S7N 5B4, Canada. email@example.com
effects of 1 min-4 h exposures to four Hg compounds (mercuric
chloride [HgCl2], methyl mercuric chloride [CH3HgCl],
p-chloromercuribenzoate [p-CMB] and thimerosal [TMS;
ethylmercurithiosalicylate]) on cell death, microtubules, actin, CD3
receptor expression, protein tyrosine phosphorylation (PTyr-P) and
intracellular calcium ([Ca2+]i) levels were investigated in YAC-1
lymphoma cells using flow cytometry. YOPRO-1 (YP) and propidium
iodide (PI) dye uptake indicated all forms of Hg tested were toxic at
concentrations ranging from 25.8-48.4 microM, with two distinct
patterns of effects. Early
and TMS-treated cells, with more
than 50% remaining YP+/PI- after 4h.
Both CH3HgCl and TMS induced complete loss of beta-tubulin
fluorescence, indicative of microtubule depolymerization and
inhibition of tubulin synthesis and/or beta-tubulin degradation,
while F-actin fluorescence diminished to a lesser degree and only
after loss beta-tubulin. CH3HgCl and TMS induced an almost immediate
two-fold increase in CD3 fluorescence, with levels returning to
baseline within minutes. With continued exposure, CD3 fluorescence
was reduced to approximately 50% of baseline values. Both compounds
also increased PTyr-P two- to three-fold immediately, with levels
returning to baseline at 4h. Similarly, two- to three-fold increases
in [Ca2+]i were noted after 1 min exposure. [Ca2+]i increased
progressively, reaching levels five- to eight-fold greater than
control values. In contrast, dye uptake was delayed with HgCl2 and
p-CMB, although cell death proceeded rapidly, with almost all
non-viable cells being late apoptotic (YP+/PI+) by 4h. p-CMB produced
early reductions in F-actin, and after 4h, complete loss of F-actin
with only partial reduction of total beta-tubulin was seen with both
p-CMB and HgCl2. HgCl2 reduced CD3 expression and PTyr-P slightly
within minutes, while p-CMB produced similar effects on CD3 only at
4h, at which time PTyr-P was increased two- to three-fold. Both
compounds increased [Ca2+]i within minutes, though levels remained
under twice the baseline concentration after 15 min exposure. With
continued exposure, [Ca2+]i increased to levels two- to five-fold
greater than control values. These findings indicate the two groups
of Hg compounds may induce cell death by distinct pathways,
reflecting interactions with different cellular targets leading to
17210217 [PubMed - indexed for MEDLINE]
2007 Jan 5;229(1-2):23-32. Epub 2006 Sep 24.
and Hg species determine the T-helper cell activation in murine
of Molecular and
Clinical Medicine, Linköping University, SE-581 85 Linköping,
mice an autoimmune
syndrome (HgIA) with T cell-dependent polyclonal B cell activation
and hypergammaglobulinemia, dose- and H-2-dependent production of
autoantibodies targeting the 34 kDa nucleolar protein fibrillarin
(AFA), and systemic immune-complex deposits. The organic mercury
species methylmercury (MeHg) and ethylmercury (EtHg--in the form of
thimerosal) induce AFA, while the other manifestations of HgIA seen
after treatment with HgCl(2) are present to varying extent. Since
these organic Hg species are converted to the autoimmunogen Hg(2+) in
the body, their primary autoimmunogen potential is uncertain and the
subject of this study. A moderate dose of HgCl(2) (8 mg/L drinking
water--internal dose 148 micro gHg/kg body weight [bw]/day) caused
the fastest AFA response, while the induction was delayed after
higher (25 mg/L) and lower (1.5 and 3 mg/L) doses. The lowest dose of
HgCl(2) inducing AFA was 1.5 mg/L drinking water which corresponded
to a renal Hg(2+) concentration of 0.53 micro g/g. Using a dose of 8
mg HgCl(2)/L this threshold concentration was reached within 24 h,
and a consistent AFA response developed after 8-10 days. The time lag
for the immunological part of the reaction leading to a consistent
AFA response was therefore 7-9 days. A dose of thimerosal close to
the threshold dose for induction of AFA (2 mg/L drinking
water--internal dose 118 micro gHg/kg bw per day), caused a renal
Hg(2+) concentration of 1.8 micro g/g. The
therefore be entirely due to
Hg(2+) formed from EtHg in the body.
The effect of organic and inorganic Hg species on T-helper type 1 and
type 2 cells during induction of AFA was assessed as the presence and
titre of AFA of the IgG1 and IgG2a isotype, respectively. EtHg
irrespectively of the dose
and time used.
A low daily dose of HgCl(2) (1.5-3 mg/L) caused a Th1-skewed AFA
response, while a moderate dose (8 mg/L) after 2 weeks resulted in a
balanced or even Th2-skewed response. Higher daily doses of HgCl(2)
(25 mg/L) caused a balanced Th2-Th1 response already from onset. In
conclusion, while metabolically formed Hg(2+) might be the main
AFA-inducing factor also after treatment with EtHg, the quality of
the Hg-induced AFA response is modified by the species of Hg as well
as the dose.
17084957 [PubMed - indexed for MEDLINE]
Matern Fetal Neonatal Med.
prospective study of thimerosal-containing Rho(D)-immune globulin
administration as a risk factor for autistic disorders.
Institute of Chronic Illnesses, Silver Spring, MD, USA.
study evaluated the relationship between prenatal mercury exposure
from thimerosal (49.55% mercury by weight)-containing Rho(D)-immune
globulins (TCRs) and autism spectrum disorders (ASDs).
Institutional Review Board of the Institute for Chronic Illnesses
approved the present study. A total of 53 consecutive non-Jewish
Caucasian patients with ASDs (Diagnostic and statistical manual of
mental disorders, fourth ed. - DSM IV) born between 1987 and 2001 who
presented to the Genetic Centers of America for outpatient
genetic/developmental evaluations were prospectively collected from
June 1, 2005 through March 31, 2006. Imaging and laboratory testing
were conducted on each patient to rule out other causal factors for
their ASDs. As race-matched controls, the frequency of Rh negativity
was determined from 926 non-Jewish Caucasian pregnant women who had
presented for outpatient prenatal genetics care to the Genetic
Centers of America between 1980 and 1989.
(28.30%) were significantly more likely (odds ratio 2.35,
95% confidence interval 1.17-4.52, p < 0.01) to have Rh-negative
mothers than controls (14.36%). Each ASD patient's mother was
determined to have been administered a TCR during her pregnancy.
results provide insights into the potential role prenatal mercury
exposure may play in some children with ASDs.
17674242 [PubMed - indexed for MEDLINE]
Toxicol Environ Health A.
2007 May 15;70(10):837-51.
series of children with apparent mercury toxic encephalopathies
manifesting with clinical symptoms of regressive autistic disorders.
Illnesses, Inc., Silver Spring, Maryland, USA.
relatedness and communication, repetitive behaviors, and
stereotypic abnormal movement patterns characterize autism spectrum
disorders (ASDs). It is clear that while genetic factors are
important to the pathogenesis of ASDs, mercury exposure can induce
immune, sensory, neurological, motor, and behavioral dysfunctions
similar to traits defining or associated with ASDs. The Institutional
Review Board of the Institute for Chronic Illnesses (Office for Human
Research Protections, U.S. Department of Health and Human Services,
IRB number IRB00005375) approved the present study. A case series of
nine patients who presented to the Genetic Centers of America for a
genetic/developmental evaluation are discussed. Eight of nine
patients (one patient was found to have an ASD due to Rett's
syndrome) (a) had regressive ASDs; (b) had elevated levels of
androgens; (c) excreted significant amounts of mercury post chelation
challenge; (d) had biochemical evidence of decreased function in
their glutathione pathways; (e) had no known significant mercury
exposure except from Thimerosal-containing vaccines/Rho(D)-immune
globulin preparations; and (f) had alternate causes for their
regressive ASDs ruled out. There was a significant dose-response
relationship between the severity of the regressive ASDs observed and
the total mercury dose children received from Thimerosal-containing
vaccines/Rho (D)-immune globulin preparations. Based
diagnoses, 8 of 9 patients examined were exposed to
significant mercury from Thimerosal-containing biologic/vaccine
preparations during their fetal/infant developmental periods, and
subsequently, between 12 and 24 mo of age, these previously normally
developing children suffered mercury toxic encephalopathies that
manifested with clinical symptoms consistent with regressive ASDs.
Evidence for mercury intoxication should be considered in the
differential diagnosis as contributing to some regressive ASDs.
17454560 [PubMed - indexed for MEDLINE]
2006 Jul;92(1):246-53. Epub 2006 Apr 19.
model via the cJun N-terminal
School of Medicine, Marshall
University, 1542 Spring Valley Drive, Huntington, WV 25704, USA.
cJun N-terminal kinase (JNK)-signaling pathway is activated in
response to a variety of stimuli, including environmental insults,
and has been implicated in neuronal apoptosis. In this study, we
investigated the role that the JNK pathway plays in neurotoxicity
caused by thimerosal, an ethylmercury-containing preservative.
SK-N-SH cells treated with thimerosal (0-10 microM) showed an
increase in the phosphorylated (active) form of JNK and cJun with 5
and 10 microM thimerosal treatment at 2 and 4 h. To examine activator
protein-1 (AP-1) transcription, cells were transfected with a pGL2
vector containing four AP-1 consensus sequences and then treated with
thimerosal (0-2.5 microM) for 24 h. Luciferase studies showed an
increase in AP-1 transcriptional activity upon thimerosal
administration. To determine the components of the AP-1 complex,
cells were transfected with a dominant negative to either cFos
(A-Fos) or cJun (TAM67). Reporter analysis showed that TAM67, but not
A-Fos, decreased AP-1 transcriptional activity, indicating a role for
cJun in this pathway. To assess which components are essential to
apoptosis, cells were treated with a cell-permeable JNK inhibitor II
(SP600125) or transfected with TAM67, and the downstream effectors of
apoptosis were analyzed. Cells pretreated with SP600125 showed
decreases in activation of caspases 9 and 3, decreases in degradation
of poly(ADP-ribose) polymerase (PARP), and decreased levels of
proapoptotic Bim, in comparison to cells treated with thimerosal
alone. However, cells transfected with TAM67 showed no changes in
those same components. Taken
neurotoxicity occurs through the JNK-signaling pathway, independent
of cJun activation, leading ultimately to apoptotic cell death.
16624850 [PubMed - indexed for MEDLINE]Free Article
and G2/M phase arrest in human leukemia cells.
School of Medicine, Keimyung University, Taegu, South
organomercury compound with sulfhydryl-reactive properties. The
ability of thimerosal to act as a sulfhydryl group is related to the
presence of mercury. Due to its antibacterial effect, thimerosal is
widely used as preservatives and has been reported to cause
chemically mediated side effects. In the present study, we showed
that the molecular mechanism of thimerosal induced apoptosis in U937
cells. Thimerosal was shown to be responsible for the inhibition of
U937 cells growth by inducing apoptosis. Treatment with 2.5-5 microM
thimerosal but not thiosalicylic acid (structural analog of
thimerosal devoid of mercury) for 12 h produced apoptosis, G(2)/M
phase arrest, and DNA fragmentation in a dose-dependent manner.
Treatment with caspase inhibitor significantly reduced
thimerosal-induced caspase 3 activation. In addition,
thimerosal-induced apoptosis was attenuated by antioxidant Mn (III)
meso-tetrakis (4-benzoic acid) porphyrin (Mn-TBAP). These
that the cytotoxic effect of thimerosal on U937 cells
is attributable to the induced apoptosis and that thimerosal-induced
apoptosis is mediated by reactive oxygen species generation and
16649253 [PubMed - indexed for MEDLINE]
2006 Sep;27(5):685-92. Epub 2006 Jun 16.
autistic children and non-autistic siblings
up-regulate heat shock protein RNA in response to thimerosal
and Pharmacology, Wake Forest University School of
Medicine, Winston-Salem, NC 27156, USA. firstname.lastname@example.org
suggesting that some autistic children are unable to
mount an adequate response following exposure to environmental
toxins. This potential deficit, coupled with the similarity in
clinical presentations of autism and some heavy metal toxicities, has
led to the suggestion that heavy metal poisoning might play a role in
the etiology of autism in uniquely susceptible individuals.
Thimerosal, an anti-microbial preservative previously added routinely
to childhood multi-dose vaccines, is composed of 49.6% ethyl mercury.
Based on the levels of this toxin that children receive through
routine immunization schedules in the first years of life, it has
been postulated that thimerosal may be a potential triggering
mechanism contributing to autism in susceptible individuals. One
potential risk factor in these individuals may be an inability to
adequately up-regulate metallothionein (MT) biosynthesis in response
to presentation of a heavy metal challenge.
To investigate this hypothesis, cultured lymphocytes (obtained from
the Autism Genetic Resource Exchange, AGRE) from autistic children
and non-autistic siblings were challenged with either 10 microM ethyl
mercury, 150 microM zinc, or fresh media (control). Following the
challenge, total RNA was extracted and used to query "whole
genome" DNA microarrays. Cultured
with zinc responded with an impressive
up-regulation of MT transcripts (at least nine different MTs were
over-expressed) while cells challenged with thimerosal responded by
up-regulating numerous heat shock protein transcripts, but not MTs.
Although there were no apparent differences between autistic and
non-autistic sibling responses in this very small sampling group, the
differences in expression profiles between those cells treated with
zinc versus thimerosal were dramatic. Determining cellular response,
at the level of gene expression, has important implications for the
understanding and treatment of conditions that result from exposure
to neurotoxic compounds.
16870260 [PubMed - indexed for MEDLINE]
Health Med. 2006 Jul-Aug;12(4):16-7.
Are mercury amalgam fillings safe for children? An evaluation of
recent research results.
EcoNugenics Inc, Santa Rosa, California, USA.
Two recent clinical trials on the safety of amalgam fillings in
children found no evidence of harmful effects from mercury-containing
dental fillings after following children for 5-7 years. This review
suggests the studies' results are limited by (1) sample sizes that were
too small to allow detection of genetic variations in mercury toxicity
at a rate of 1 in 100 or lower, (2) a lack of control for other sources
of mercury, and (3) a population that may have been skewed by excluding
children with autism during a time when autism was escalating due, in
part, to increased frequency of thimerosal-containing vaccine use.
PMID: 16862738 [PubMed - indexed
meta-analysis epidemiological assessment of neurodevelopmental
disorders following vaccines administered from 1994 through 2000 in
the United States.
Institute for Chronic Illnesses, Inc., Silver Spring, MD 20905, USA.
is an ethylmercury-containing compound (49.6% mercury by weight) used
as at the preservative level in vaccines (0.005% to 0.01%).
modeling in a meta-analysis epidemiological assessment of the Vaccine
Adverse Event Reporting System (VAERS) for neurodevelopment disorders
(NDs) reported following Diphtheria-Tetanus-whole-cell-Pertussis
(DTP) vaccines in comparison to
Diphtheria-Tetanus-whole-cell-Pertussis-Haemophilus Influenzae Type b
(DTPH) vaccines (administered: 1994-1997) and following
Thimerosal-containing Diphtheria-Tetanus-acellular-Pertussis (DTaP),
vaccines in comparison to Thimerosal-free DTaP vaccines
(administered: 1997-2000), was undertaken.
(sex, age, vaccine type, vaccine manufacturer)
risks of autism, speech disorders, mental retardation, personality
disorders, thinking abnormalities, ataxia, and NDs in general, with
minimal systematic error or confounding, were associated with TCV
is clear from the results of the present epidemiological study and
other recently published data associating mercury exposure with
childhood NDs, additional ND research should be undertaken in the
context of evaluating mercury-associated exposures, especially from
16807526 [PubMed - indexed for MEDLINE]
Microbiol Immunol Hung.
on the track of thimerosal. Review.
Research Group of the Hungarian Academy of Sciences,
University of Debrecen, Nagyerdei krt. 98, H-4012 Debrecen, Hungary.
thimerosal is one of the most important organic
mercury compounds human populations are exposed to. It has toxic
effect on several cell lines, and it also induces programmed cell
death in in vitro experiments.
Association is suggested between application of thimerosal-containing
vaccines and the occurrence of neurodevelopmental disorders, like
autism. While specific recommendations were made to eliminate
thimerosal from vaccines, consistent evidence is still lacking for an
association of exposure and disease. Unfortunately,
very hard to study the molecular background of complex human
diseases directly; however, investigations on more simple model
organisms may lead to a better understanding of thimerosal as a
possible disease inducing factor.
15957237 [PubMed - indexed for MEDLINE]
2005 Apr;11(4):CR160-70. Epub 2005 Mar 24.
two-phased population epidemiological study of the safety of
thimerosal-containing vaccines: a follow-up analysis.
is an ethylmercury-containing preservative in vaccines. Toxicokinetic
studies have shown children received doses of mercury from
thimerosal-containing vaccines (TCVs) that were in excess of safety
guidelines. Previously, an ecological study showing a significant
association between TCVs and neurodevelopmental disorders (NDs) in
the US was published in this journal.
two phased population-based epidemiological study was undertaken.
Phase one evaluated reported NDs to the Vaccine Adverse Event
Reporting System (VAERS) following thimerosal-containing
Diphtheria-Tetanus-acellular-Pertussis (DTaP) vaccines in comparison
to thimerosal-free DTaP vaccines administered from 1997 through 2001.
Phase two evaluated the automated Vaccine Safety Datalink (VSD) for
cumulative exposures to mercury from TCVs at 1-, 2-, 3-, and
6-months-of-age for infants born from 1992 through 1997 and the
eventual risk of developing NDs.
one showed significantly increased risks for autism, speech
disorders, mental retardation, personality disorders, and thinking
abnormalities reported to VAERS following thimerosal-containing DTaP
vaccines in comparison to thimerosal-free DTaP vaccines. Phase two
showed significant associations between cumulative exposures to
thimerosal and the following types of NDs: unspecified developmental
delay, tics, attention deficit disorder (ADD), language delay, speech
delay, and neurodevelopmental delays in general.
that exposure to mercury from TCVs administered in the
US was a consistent significant risk factor for the development of
It is clear from these data and other recent publications linking
TCVs with NDs that additional ND research should be undertaken in the
context of evaluating mercury-associated exposures and
thimerosal-free vaccines should be made available.
15795695 [PubMed - indexed for MEDLINE]
Hospital Freiburg, Germany. email@example.com
causes of autism and neurodevelopmental disorders are unknown.
Genetic and environmental risk factors seem to be involved. Because
of an observed increase in autism in the last decades, which
parallels cumulative mercury exposure, it was proposed that autism
may be in part caused by mercury. We review the evidence for this
proposal. Several epidemiological studies failed to find a
correlation between mercury exposure through thimerosal, a
preservative used in vaccines, and the risk of autism. Recently, it
was found that autistic children had a higher mercury exposure during
pregnancy due to maternal dental amalgam and thimerosal-containing
immunoglobulin shots. It was hypothesized that children with autism
have a decreased detoxification capacity due to genetic polymorphism.
In vitro, mercury and thimerosal in levels found several days after
vaccination inhibit methionine synthetase (MS) by 50%. Normal
function of MS is crucial in biochemical steps necessary for brain
development, attention and production of glutathione, an important
antioxidative and detoxifying agent. Repetitive
neurobehavioral deteriorations in
autoimmune susceptible mice, increased oxidative stress and decreased
intracellular levels of glutathione in vitro. Subsequently, autistic
children have significantly decreased level of reduced glutathione.
Promising treatments of autism involve detoxification of mercury, and
supplementation of deficient metabolites.
16264412 [PubMed - indexed for MEDLINE]
levels in infant monkeys exposed to
methylmercury or vaccines containing thimerosal.
Sciences, School of Public
Health and Community Medicine, University of Washington, Seattle,
Washington 98195, USA. firstname.lastname@example.org
been used in manufacturing vaccines since
the 1930s. Reports have indicated that infants can receive
ethylmercury (in the form of thimerosal) at or above the U.S.
Environmental Protection Agency guidelines for methylmercury
exposure, depending on the exact vaccinations, schedule, and size of
the infant. In this study we compared the systemic disposition and
brain distribution of total and inorganic mercury in infant monkeys
after thimerosal exposure with those exposed to MeHg. Monkeys were
exposed to MeHg (via oral gavage) or vaccines containing thimerosal
(via intramuscular injection) at birth and 1, 2, and 3 weeks of age.
Total blood Hg levels were determined 2, 4, and 7 days after each
exposure. Total and inorganic brain Hg levels were assessed 2, 4, 7,
or 28 days after the last exposure. The initial and terminal
half-life of Hg in blood after thimerosal exposure was 2.1 and 8.6
days, respectively, which are significantly shorter than the
elimination half-life of Hg after MeHg exposure at 21.5 days.
were significantly lower by
approximately 3-fold for the thimerosal-exposed monkeys when compared
with the MeHg infants, whereas the average brain-to-blood
concentration ratio was slightly higher for the thimerosal-exposed
monkeys (3.5 +/- 0.5 vs. 2.5 +/- 0.3). A higher percentage of the
total Hg in the brain was in the form of inorganic Hg for the
thimerosal-exposed monkeys (34% vs. 7%).
The results indicate that MeHg is not a suitable reference for risk
assessment from exposure to thimerosal-derived Hg. Knowledge of the
toxicokinetics and developmental toxicity of thimerosal is needed to
afford a meaningful assessment of the developmental effects of
16079072 [PubMed - indexed for MEDLINE]PMCID: PMC1280342Free PMC
human neuroblastoma cell
School of Medicine, Marshall
University, Huntington, WV 25704-9388, USA.
be a public health issue due to
their deleterious effects on immune, renal and neurological function.
Recently the safety of thimerosal, an ethyl mercury-containing
preservative used in vaccines, has been questioned due to exposure of
infants during immunization. Mercurials have been reported to cause
apoptosis in cultured neurons; however, the signaling pathways
resulting in cell death have not been well characterized. Therefore,
the objective of this study was to identify the mode of cell death in
an in vitro model of thimerosal-induced neurotoxicity, and more
specifically, to elucidate signaling pathways which might serve as
pharmacological targets. Within 2 h of thimerosal exposure (5 microM)
to the human neuroblastoma cell line, SK-N-SH, morphological changes,
including membrane alterations and cell shrinkage, were observed.
Cell viability, assessed by measurement of lactate dehydrogenase
(LDH) activity in the medium, as well as the
3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT)
assay, showed a time- and concentration-dependent decrease in cell
survival upon thimerosal exposure. In cells treated for 24 h with
thimerosal, fluorescence microscopy indicated cells undergoing both
apoptosis and oncosis/necrosis. To identify the apoptotic pathway
associated with thimerosal-mediated cell death, we first evaluated
the mitochondrial cascade, as both inorganic and organic mercurials
have been reported to accumulate in the organelle. Cytochrome c was
shown to leak from the mitochondria, followed by caspase 9 cleavage
within 8 h of treatment. In addition, poly(ADP-ribose) polymerase
(PARP) was cleaved to form a 85 kDa fragment following maximal
caspase 3 activation at 24 h. Taken
effects on the
cytoarchitecture by thimerosal and initiation of
15869795 [PubMed - indexed for MEDLINE]
2005 Jul;86(1):132-40. Epub 2005 Apr 20.
transduction and cell death in
Laboratory for Neurotoxicity
Studies, Virginia Tech, 1 Duckpond Drive, Blacksburg, Virginia
for differentiation and
survival of the developing nervous system.
The present study examined the effects of the organic mercury
compound thimerosal on nerve growth factor signal transduction and
cell death in a human neuroblastoma cell line (SH-SY5Y cells).
Following exposure to 100 ng/ml NGF and increasing concentrations of
thimerosal (1 nM-10 microM), we measured the activation of TrkA,
MAPK, and PKC-delta. In controls, the activation of TrkA MAPK and
PKC-delta peaked after 5 min of exposure to NGF and then decreased
but was still detectable at 60 min. Concurrent exposure to increasing
concentrations of thimerosal and NGF for 5 min resulted in a
concentration-dependent decrease in TrkA and MAPK phosphorylation,
which was evident at 50 nM for TrkA and 100 nM for MAPK. Cell
viability was assessed by the LDH assay. Following 24-h exposure to
increasing concentrations of thimerosal, the EC50 for cell death in
the presence or absence of NGF was 596 nM and 38.7 nM, respectively.
Following 48-h exposure to increasing concentrations of thimerosal,
the EC50 for cell death in the presence and absence of NGF was 105 nM
and 4.35 nM, respectively. This suggests that NGF provides protection
against thimerosal cytotoxicity. To determine if apoptotic versus
necrotic cell death was occurring, oligonucleosomal fragmented DNA
was quantified by ELISA. Control levels of fragmented DNA were
similar in both the presence and absence of NGF. With and without
NGF, thimerosal caused elevated levels of fragmented DNA appearing at
0.01 microM (apoptosis) to decrease at concentrations >1 microM
alter NGF-induced signaling in
neurotrophin-treated cells at concentrations lower than those
responsible for cell death.
15843506 [PubMed - indexed for MEDLINE]Free Article
thimerosal, a preservative in
vaccines, on lymphocytes dissociated from rat thymic glands.
Integrated Arts and Sciences, The
University of Tokushima, Minami-Jyosanjima 1-1, Tokushima 770-8502,
is a concern on the part of public health community that adverse
health consequence by thimerosal, a preservative in vaccines for
infants, may occur among infants during immunization schedule.
Therefore, the cytotoxic action of thimerosal was examined on
lymphocytes dissociated from thymic glands of young rats using a flow
cytometer and respective fluorescent probes for monitoring changes in
intracellular Ca2+ concentration ([Ca2+]i) and membrane potential,
and for discriminating intact living cells, apoptotic living cells
and dead cells. Incubation with thimerosal at 3 microM or more (up to
30 microM) for 60 min depolarized the membranes, associated with
increasing the [Ca2+]i. Thimerosal
apoptotic change in membranes of almost all
living cells. Furthermore, the prolonged incubation with 30 microM
thimerosal induced a loss of membrane integrity, leading to cell
Since the blood concentration of thimerosal after receiving vaccines
is theoretically submicromolar, it may be unlikely that thimerosal
affects lymphocytes of infants.
15649632 [PubMed - indexed for MEDLINE]
with glutathione precursors.
for Medical Sciences and
Arkansas Children's Hospital Research Institute, Little Rock, AR
72202, USA. email@example.com
ethyl mercury that has been used
for years as a preservative in many infant vaccines and in flu
vaccines. Environmental methyl mercury has been shown to be highly
neurotoxic, especially to the developing brain. Because
for thiol (sulfhydryl (-SH)) groups, the
thiol-containing antioxidant, glutathione (GSH), provides the major
intracellular defense against mercury-induced neurotoxicity.
have lower levels of GSH and
increased sensitivity to thimerosol toxicity
compared to glioblastoma cells that have higher basal levels of
intracellular GSH. Thimerosal-induced
of intracellular GSH in
both cell lines.
Pretreatment with 100 microM glutathione ethyl ester or
N-acetylcysteine (NAC), but not methionine, resulted in a significant
increase in intracellular GSH in both cell types. Further,
pretreatment of the cells with glutathione ethyl ester or NAC
prevented cytotoxicity with exposure to 15 microM Thimerosal.
Although Thimerosal has been recently removed from most children's
vaccines, it is still present in flu vaccines given to pregnant
women, the elderly, and to children in developing countries. The
potential protective effect of GSH or NAC against mercury toxicity
warrants further research as possible adjunct therapy to individuals
still receiving Thimerosal-containing vaccinations.
15527868 [PubMed - indexed for MEDLINE]
J Mol Med.
cell apoptosis by causing cytochrome c and
apoptosis-inducing factor release from mitochondria.
University of California, Irvine, CA 92697, USA.
is a worldwide increasing concern over the neurological risks of
thimerosal (ethylmercury thiosalicylate) which is an organic mercury
compound that is commonly used as an antimicrobial preservative. In
we show that thimerosal, at nanomolar concentrations,
induces neuronal cell death through the mitochondrial pathway.
Thimerosal, in a concentration- and time-dependent manner, decreased
cell viability as assessed by calcein-ethidium staining and caused
apoptosis detected by Hoechst 33258 dye. Thimerosal-induced apoptosis
was associated with depolarization of mitochondrial membrane,
generation of reactive oxygen species, and release of cytochrome c
and apoptosis-inducing factor (AIF) from mitochondria to cytosol.
Although thimerosal did not affect cellular expression of Bax at the
protein level, we observed translocation of Bax from cytosol to
mitochondria. Finally, caspase-9 and caspase-3 were activated in the
absence of caspase-8 activation. Our
that thimerosal causes apoptosis in neuroblastoma cells
by changing the mitochondrial microenvironment.
16273274 [PubMed - indexed for MEDLINE]