Investigations on the binding of ethylmercury from thiomersal to proteins in influenza vaccines

This study investigates the binding of ethylmercury (EtHg⁺) released from the preservative thiomersal by hydrolysis to proteins in influenza vaccines via ultrafiltration and subsequent total reflection x-ray fluorescence (TXRF) analysis as well as size exclusion chromatography (SEC) hyphenated to inductively coupled plasma-mass spectrometry (ICP-MS). Binding of EtHg⁺ to the protein fraction was shown by means of ultrafiltration and TXRF in a qualitative matter. SEC/ICP-MS was applied to gain more information about the molecular weight of the bound protein and quantitative information. First experiments showed the necessity of a rinsing step during elution with a thiol-containing compound to prevent unspecific binding or mercury species to the chromatographic system. Adduct formation of EtHg⁺ and a high-molecular compound could be observed for different concentrations of EtHg⁺ applied. The mercury-containing fraction was larger than 133 kDa, indicating binding to hemagglutinin, which is the active ingredient in influenza vaccines. The applied SEC/ICP-MS method allowed for external calibration with EtHg⁺ and a binding of 141 μg L^-1 Hg was shown for a vaccine solution that was incubated with EtHg⁺ (25 mg L^-1 Hg).

Neurodevelopmental Disorders Following Thimerosal-Containing Childhood Immunizations: A Follow-Up Analysis

The authors previously published the first epidemiological study from the United States associating thimerosal from childhood vaccines with neurodevelopmental disorders (NDs) based upon assessment of the Vaccine Adverse Event Reporting System (VAERS). A number of years have gone by since their previous analysis of the VAERS. The present study was undertaken to determine whether the previously observed effect between thimerosal-containing childhood vaccines and NDs are still apparent in the VAERS as children have had a chance to further mature and potentially be diagnosed with additional NDs. In the present study, a cohort of children receiving thimerosal-containing diphtheria-tetanus-acellular pertussis (DTaP) vaccines in comparison to a cohort of children receiving thimerosal-free DTaP vaccines administered from 1997 through 2000 based upon an assessment of adverse events reported to the VAERS were evaluated. It was determined that there were significantly increased odds ratios (ORs) for autism (OR = 1.8, p < .05), mental retardation (OR = 2.6, p < .002), speech disorder (OR = 2.1, p <.02), personality disorders (OR=2.6, p <.01), and thinking abnormality (OR=8.2, p <.01) adverse events reported to the VAERS following thimerosal-containing DTaP vaccines in comparison to thimerosal-free DTaP vaccines. Potential confounders and reporting biases were found to be minimal in this assessment of the VAERS. It was observed, even though the media has reported a potential association between autism and thimerosal exposure, that the other NDs analyzed in this assessment of the VAERS had significantly higher ORs than autism following thimerosal-containing DTaP vaccines in comparison to thimerosal-free DTaP vaccines. The present study provides additional epidemiological evidence supporting previous epidemiological, clinical and experimental evidence that administration of thimerosal-containing vaccines in the United States resulted in a significant number of children developing NDs.

A historically-controlled Phase III study in adults to characterize the acceptability of a process change for manufacturing inactivated quadrivalent influenza vaccine

BACKGROUND

An inactivated quadrivalent influenza vaccine (QIV) was recently licenced in the US as a thimerosal-free formulation presented in a pre-filled syringe. A multidose presentation is preferred in some settings due to reduced acquisition and cold storage costs. We assessed the immunogenicity and safety of a thimerosal-containing QIV formulated using a new manufacturing process for presentation in multidose vials.

METHODS

Two Phase III non-randomized studies separately evaluated inactivated trivalent influenza vaccine (TIV; 2010-2011; historical control) and a QIV (2011-2012). The QIV contained the same strains as the TIV plus an additional B strain. Both vaccines contained thimerosal to allow multidose presentation: this preservative was added to the QIV during the final formulation step using a new process, whereas it was added to the TIV early in the manufacturing process using an established method. The TIV study included 50 and 70 subjects aged 18-60 and >60 years, respectively; the QIV study included 56 subjects in each age stratum. Immunogenicity was assessed using hemagglutination-inhibition (HI) assays. Reactogenicity was assessed during the 4-day post-vaccination periods and unsolicited adverse events (AEs) were assessed during the 21-day post-vaccination periods.

RESULTS

The TIV and QIV were immunogenic in both age strata. With the QIV and TIV respectively, the seroconversion rates were 48.2-62.7% and 71.4-83.7% for influenza A, and 33.9-62.5% and 67.3-72.9% for influenza B. With the QIV and TIV respectively, the seroprotection rates were 92.9-98.2% and 98.2-100% for influenza A, and 88.6-100% and 95.9-98.6% for influenza B. Pre-vaccination titers were higher in the QIV versus TIV study which confounds a direct comparison and likely explains the lower seroconversion rates observed in the QIV study. There were no safety concerns raised with TIV or QIV.

CONCLUSIONS

The thimerosal-containing QIV formulated using a new process was immunogenic, conforming to regulatory acceptance criteria, with a reactogenicity and safety profile in line with the TIV manufactured using a licensed process. These results support acceptability of a manufacturing process change in which the thimerosal preservative is added at the point at which batches are filled into multidose vials.

TRIAL REGISTRATION

These trials were registered at ClinicalTrials.gov: NCT01440387; NCT01153685.

Automated speciation of mercury in the hair of breastfed infants exposed to ethylmercury from thimerosal-containing vaccines

A simplified thiourea-based chromatography method, originally developed for methyl and inorganic mercury, was adapted to separate methylmercury (MeHg), ethylmercury (EtHg), and inorganic mercury (Hg(II)) in infants' hair. Samples were weighed and leached with an acidic thiourea solution. Leachates were concentrated on a polymeric resin prior to analysis by Hg-thiourea liquid chromatography/cold vapor atomic fluorescence spectrometry. All but one sample showed small amounts of EtHg, and four of the six analyzed samples had proportionally higher Hg(II) as a percent of total Hg. Breastfed infants from riverine Amazonian communities are exposed to mercury in breast milk (from high levels of maternal sources that include both fish consumption and dental amalgam) and to EtHg in vaccines (from thimerosal). The method proved sensitive enough to detect and quantify acute EtHg exposure after shots of thimerosal-containing vaccines. Based on work with MeHg and Hg(II), estimated detection limits for this method are 0.050, 0.10, and 0.10 ng g⁻¹ for MeHg, Hg(II), and EtHg, respectively, for a 20-mg sample. Specific limits depend on the amount of sample extracted and the amount of extract injected.

[Lack of association between thimerosal-containing vaccines and autism]

In Poland, administered childhood vaccines still contain thimerosal as a preservative. Despite the access to mercury free formulas, the most of children are still vaccinated by thimerosal-containing vaccines (TCV) owing to economical reasons. That circumstances caused the rising discussion on potential harmful influence of TCVs on children health. The objective of this analysis was to determine an association of TCVs exposure with the risk of autism. Study population included 96 cases diagnosed with childhood or atypical autism and 192 controls matched individually by year of birth, gender, and physician's practice. Data on autism diagnose and vaccination history were from GPs. Data on the other possible autism risk factors were collected from mothers. Conditional logistic regression was used to assess the risk of autism due to TCVs exposure. No significant association was found between TCVs exposure and autism. After adjusting to potential confounders, odds ratios of the risk of autism developing for infants vaccinated with TCVs were 1.52 (95% CI: 0.29-11.11) for doses 12.5-87.5 microg, 2.78 (95% CI: 0.29-11.11) for 100-137.5 microg and 1.97 (95% CI: 0.37-18.95) for these exposed > or = 150 microg. Our study revealed no evidence of an association between TCVs and autism.

Technology of eye drops containing metronidazole

The aim of the studies was to determine the stability of metronidazole using UV spectrophotometric method in 0.5% w/w eye drops which were prepared under aseptic conditions and thermally sterilized. 0.9% solution of NaCl, 5% glucose and phosphate buffers of pH 6.97 and 6.81 were used as the solvents of metronidazole in the drops. Thiomersal and phenylmercuric borate were used to preserve the drops. The viscosity of the eye drops was increased using the solution of polyvinyl alcohol. The drops were stored in tightly closed glass infusion bottles, protected from light. For the stability of analysis a long-term assay was used under controlled conditions following the requirements of ICH, i.e., the time of storage was 24 months at the constant temperature of 25 +/- 2 degrees C and constant humidity of 60% +/- 2% RH. The eye drops containing metronidazole were significantly physically and chemically stable: after 24 months of storage the metronidazole concentration in the drops was close to 100% of the initial concentration. The drops were colorless and transparent. Physical and chemical properties such as pH, osmotic pressure and viscosity underwent insignificant changes during the storage. The preservation test showed that the degree of reduction of the pharmacopeal strains of micro-organisms in freshly prepared drops and in those stored for 24 months at the temperature of 25 +/- 20 degrees C was in agreement with the requirements of Ph. Eur. 6.

Changes in children hair-Hg concentrations during the first 5 years: Maternal, environmental and iatrogenic modifying factors

Children are exposed to Hg from mothers (via placenta and lactation), environment (food), and in many parts of the world by thimerosal-containing vaccines (TCV) during immunization. Neurodevelopment studies based on infant hair-Hg (HHg) have been designed without explicit attention to the factors associated with changes in infant physiology and Hg sources of exposure. A longitudinal study of changes in HHg concentrations from birth to 5 years was done in a sample of children from Porto Velho (Rondonia), Brazilian Amazonia. The study extracted information from the asymmetry associated with maternal and infant HHg changes at specified sampling: birth (fetal exposure), 6 months of exclusive breastfeeding, 36 months (weaning) and 60 months (pre-school). The distribution of HHg in breastfed infants followed a pattern different from their mothers. While mothers had the highest HHg concentrations at childbirth, infants showed the highest HHg values at 6 months after the recommended full schedule (six shots) of immunization with TCV; after that, the downward trend in HHg shown by children coincided with both weaning and less frequent vaccination period (5 years). Extended lactation (up to 36 months) was not significantly associated with HHg of infants or mothers; however, significant association (Spearman's r) between maternal and infant HHg concentration was seen at birth (r=0.3534; P=0.001), 6 months (r=0.4793; P<0.0001), 3 years (r=0.0122; P=0.012) and 5 years (r=0.0357; P=0.005). Maternal postpartum metabolic changes, infant development and transitional diets and possibly Hg from TCV contribute to the asymmetry of HHg changes between mothers and children.

Use of adsorption process to remove organic mercury thimerosal from industrial process wastewater

Carbon adsorption process is tested for removal of high concentration of organic mercury (thimerosal) from industrial process wastewater, in batch and continuously flow through column systems. The organic mercury concentration in the process wastewater is about 1123 mg/L due to the thimerosal compound. Four commercially available adsorbents are tested for mercury removal and they are: Calgon F-400 granular activated carbon (GAC), CB II GAC, Mersorb GAC and an ion-exchange resin Amberlite GT73. The adsorption capacity of each adsorbent is described by the Freundlich isotherm model at pH 3.0, 9.5 and 11.0 in batch isotherm experiments. Acidic pH was favorable for thimerosal adsorption onto the GACs. Columns-in-series experiments are conducted with 30-180 min empty bed contact times (EBCTs). Mercury breakthrough of 30 mg/L occurred after about 47 h (96 Bed Volume Fed (BVF)) of operation, and 97 h (197 BVF) with 120 min EBCT and 180 min EBCT, respectively. Most of the mercury removal is attributed to the 1st adsorbent column. Increase in contact time by additional adsorbent columns did not lower the effluent mercury concentration below 30 mg/L. However, at a lower influent wastewater pH 3, the mercury effluent concentration decreased to less than 7 mg/L for up to 90 h of column operation (183 BVF).

Exposure to mercury during the first six months via human milk and vaccines: modifying risk factors

Breastfeeding is the best natural protection infants have against morbidity and mortality, and the development of safe and effective vaccines has made it possible to immunize children against infectious disease. Both of these mechanisms for ensuring good health in children may be compromised by contact with mercury (Hg). Maternal exposure to environmental Hg during pregnancy can predispose nursing children to neurodevelopmental disorders. Despite the World Health Organization assurance that thimerosal-preserved vaccines are safe to use in infants, the United States, the European Union, and dozens of other countries have eliminated thimerosal as a vaccine preservative and stopped the immunization of children with such vaccines. Because of the increase in environmental pollution and the need to produce cheap and safe vaccines, there is a need to address the uncertainty of vaccine-ethylmercury risk of toxicity and Hg exposure during breastfeeding.

The toxicology of mercury and its chemical compounds

This review covers the toxicology of mercury and its compounds. Special attention is paid to those forms of mercury of current public health concern. Human exposure to the vapor of metallic mercury dates back to antiquity but continues today in occupational settings and from dental amalgam. Health risks from methylmercury in edible tissues of fish have been the subject of several large epidemiological investigations and continue to be the subject of intense debate. Ethylmercury in the form of a preservative, thimerosal, added to certain vaccines, is the most recent form of mercury that has become a public health concern. The review leads to general discussion of evolutionary aspects of mercury, protective and toxic mechanisms, and ends on a note that mercury is still an "element of mystery."

Dose and Hg species determine the T-helper cell activation in murine autoimmunity

Inorganic mercury (mercuric chloride--HgCl(2)) induces in 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 autoimmunogen effect of EtHg might 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 induced a persistent Th1-skewed response 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.

Discovery of potent inhibitors of pseudomonal quorum sensing via pharmacophore modeling and in silico screening

HipHop-Refine was employed to derive a binding hypothesis for pseudomonal quorum sensing (QS) antagonists. The model was employed as 3D search query to screen the National Cancer Institute (NCI) database. One of the hits illustrated nanomolar QS inhibitory activity. The fact that this compound contained tetravalent lead (Pb) prompted us to evaluate the activities of phenyl mercuric nitrate and thimerosal, both fit the binding pharmacophore. The two mercurials illustrated nanomolar to low micromolar IC50 inhibitory values against pseudomonal QS. The three compounds represent a new class of QS inhibitors.

Analysis of acrylamide in food products by in-line preconcentration capillary zone electrophoresis

Two in-line preconcentration capillary zone electrophoresis (CZE) methods (field amplified sample injection (FASI) and stacking with sample matrix removal (LVSS)) have been evaluated for the analysis of acrylamide (AA) in foodstuffs. To allow the determination of AA by CZE, it was derivatized using 2-mercaptobenzoic acid. For FASI, the optimum conditions were water at pH > or = 10 adjusted with NH3 as sample solvent, 35 s hydrodynamic injection (0.5 psi) of a water plug, 35 s of electrokinetic injection (-10 kV) of the sample, and 6s hydrodynamic injection (0.5 psi) of another water plug to prevent AA removal by EOF. In stacking with sample matrix removal, the reversal time was found to be around 3.3 min. A 40 mM phosphate buffer (pH 8.5) was used as carrier electrolyte for CZE separation in both cases. For both FASI and LVSS methods, linear calibration curves over the range studied (10-1000 microg L(-1) and 25-1000 microg L(-1), respectively), limit of detection (LOD) on standards (1 microg L(-1) for FASI and 7 microg L(-1) for LVSS), limit of detection on samples (3 ng g(-1) for FASI and 20 ng g(-1) for LVSS) and both run-to-run (up to 14% for concentration and 0.8% for time values) and day-to-day precisions (up to 16% and 5% for concentration and time values, respectively) were established. Due to the lower detection limits obtained with the FASI-CZE this method was applied to the analysis of AA in different foodstuffs such as biscuits, cereals, crisp bread, snacks and coffee, and the results were compared with those obtained by LC-MS/MS.

Immuno-biochemical evaluations of phenol and thimerosal as antigen preservatives in Montenegro skin test

Montenegro skin test (MST) represents the main complementary diagnostic test for tegumentary leishmaniases (TL) in endemic regions. Most antigen formulations used for the MST contain thimerosal as preservative. The Food and Drug Administration (FDA), however, recommended reducing or eliminating thimerosal from vaccines and other biological reagents and the Agência Nacional de Vigilância Sanitária (ANVISA) in Brazil, prohibited the use of mercurial compounds in immunobiologicals. In the search for an alternative stabilizer, phenol and thimerosal were tested as antigen preservatives in MST. Formulations were tested when fresh and after a 12-month storage at 4 degrees C in TL confirmed mice and human patients, and were evaluated for protein constitution by SDS-PAGE, Western blot and anti-gp63 ELISA. In mice, a decrease in the diagnostic effectiveness in merthiolate formulation was observed after a 12-month storage. SDS-PAGE, Western blot and anti-gp63 ELISA analyses showed a degradation of antigen proteins in both formulations after 12-month storage and that phenol-preserved antigen was quantitatively and qualitatively better than the merthiolate-preserved one. In patients, the average of induration diameter was larger in fresh antigens (p<0.05). However, storage time did not jeopardize their diagnostic capacity. No non-specific reactions produced by phenol or merthiolate were observed neither in humans nor in mice. Phenol could be a good alternative to replace the merthiolate in MST, and despite the proteolytic activity, antigens remain viable for at least 12 months.

Antioxidant activity of cysteine, tryptophan, and methionine residues in continuous phase beta-lactoglobulin in oil-in-water emulsions

Proteins dispersed in the continuous phase of oil-in-water emulsions are capable of inhibiting lipid oxidation reactions. The antioxidant activity of these proteins is thought to encompass both free radical scavenging by amino acid residues and chelation of prooxidative transition metals; however, the precise mechanism by which this occurs remains unclear. In this study, the oxidative stability of cysteine, tryptophan, and methionine residues in continuous phase beta-lactoglobulin (beta-Lg) in a Brij-stabilized menhaden oil-in-water emulsion was determined. The presence of low concentrations of continuous phase beta-Lg (250 and 750 microg/mL) significantly inhibited lipid oxidation as determined by lipid hydroperoxides and thiobarbituric acid reactive substances analysis. It was observed that cysteine oxidized before tryptophan in beta-Lg, and both residues oxidized before lipid oxidation could be detected. No oxidation of the methionine residues of beta-Lg was observed despite its reported high oxidative susceptibility. It is conceivable that surface exposure of amino acid residues greatly affects their oxidation kinetics, which may explain why some residues are preferentially oxidized relative to others. Further elucidation of the mechanisms governing free radical scavenging of amino acids could lead to more effective applications of proteins as antioxidants within oil-in-water food emulsions.

When science is not enough – a risk/benefit profile of thiomersal-containing vaccines

Without a preservative, such as thiomersal (known as thimerosal in the US), multi-dose liquid presentations of vaccine are vulnerable to bacteriological contamination that can result in death or serious illness of the recipient. Concerns about levels of mercury exposure from thiomersal-containing vaccines were first raised in the US during 1999 in the context of Hepatitis B vaccine for newborns. Since then, a large body of evidence from animal and epidemiological studies has accumulated on the safety of thiomersal. Ironically, these data have become largely irrelevant in wealthy countries, where mono-dose, thiomersal-free vaccines have been introduced as a precautionary measure in almost all childhood vaccines, in part related to residual public scepticism. In poor countries, multi-dose vials remain important for vaccine delivery. There is a real danger that this controversy may result in the loss to the world of thiomersal as a preservative, simply from popular pressure. In reality, it would be impossible to cease overnight using thiomersal and maintain the supply of vital vaccines. This paper reviews and summarises the data available from published studies on mercury toxicity, and thiomersal in vaccines in particular, that overwhelmingly indicate continued use of thiomersal is safe in those countries where it is most needed.

Increased Ethyl Mercury Load in Protein A Immunoadsorption

Immunoadsorption is an adsorption technique for extracorporeal removal of circulating autoantibodies in autoimmune diseases. To prevent microbial growth during storage, the protein A columns are primed with thiomersal, which contains toxic ethyl mercury, which may be released during the procedure and potentially begin to accumulate and become toxic. To reduce the thiomersal-related mercury release during immunoadsorption treatment, we introduced a modified rinsing solution containing N-acetylcysteine, which is an avid mercury scavenger. Thirteen patients received 17 protein A immunoadsorption treatments and their venous blood samples were collected immediately before and after each session. The total blood mercury levels were measured by atomic absorption spectrometry, and the ethyl mercury levels by atomic fluorescence spectrometry. Following the manufacturer's recommendations, we used 600 mg of N-acetylcysteine to rinse the mercury from protein-loaded columns before each immunoadsorption treatment. After immunoadsorption, the ethyl mercury levels increased from 0.148 +/- 0.402 ng/g to 2.026 +/- 1.944 ng/g (P < 0.001), and the total blood mercury levels increased from 2.447 +/- 3.065 ng/g to 20.437 +/- 28.603 ng/g (P = 0.02). The post-treatment values of total blood mercury exceeded the upper safety level of 5 ng/g in all 17 immunoadsorption treatments, but no patient developed clinical signs of mercury toxicity. The results of our study showed an increase in total blood mercury and ethyl mercury levels during the immunoadsorption treatments, suggesting mercury release from thiomersal-primed columns despite the addition of N-acetylcysteine to the rinsing solution.

Immunosuppressive and autoimmune effects of thimerosal in mice

The possible health effects of the organic mercury compound thimerosal (ethylmercurithiosalicylate), which is rapidly metabolized to ethylmercury (EtHg), have recently been much debated and the effect of this compound on the immune system is largely unknown. We therefore studied the effect of thimerosal by treating A.SW (H-2s) mice, susceptible to induction of autoimmunity by heavy metals, with 10 mg thimerosal/L drinking water (internal dose ca 590 microg Hg/kg body weight/day) for up to 30 days. The lymph node expression of IL-2 and IL-15 mRNA was increased after 2 days, and of IL-4 and IFN-gamma mRNA after 6 and 14 days. During the first 14 days treatment, the number of splenocytes, including T and B cells as well as Ig-secreting cells decreased. A strong immunostimulation superseded after 30 days treatment with increase in splenic weight, number of splenocytes including T and B cells and Ig-secreting cells, and Th2- as well as Th-1-dependent serum immunoglobulins. Antinucleolar antibodies (ANoA) targeting the 34-kDa nucleolar protein fibrillarin, and systemic immune-complex deposits developed. The H-2s strains SJL and B10.S also responded to thimerosal treatment with ANoA. The A.TL and B10.TL strain, sharing background genes with the A.SW and B10.S strain, respectively, but with a different H-2 haplotype (t1), did not develop ANoA, linking the susceptibility to H-2. Thimerosal-treated H-2s mice homozygous for the nu mutation (SJL-nu/nu), or lacking the T-cell co-stimulatory molecule CD28 (B10.S-CD28-/-), did not develop ANoA, which showed that the autoimmune response is T-cell dependent. Using H-2s strains with targeted mutations, we found that IFN-gamma and IL-6, but not IL-4, is important for induction of ANoA by thimerosal. The maximum added renal concentration of thimerosal (EtHg) and inorganic mercury occurred after 14 days treatment and was 81 microg Hg/g. EtHg made up 59% and inorganic mercury 41% of the renal mercury. In conclusion, the organic mercury compound thimerosal (EtHg) has initial immunosuppressive effects similar to those of MeHg. However, in contrast to MeHg, thimerosal treatment leads in genetically susceptible mice to a second phase with strong immunostimulation and autoimmunity, which is T-cell dependent, H-2 linked and may at least partly be due to the inorganic mercury derived from the metabolism of ethyl mercury.

Chemical compounds that target thiol-disulfide groups on mononuclear phagocytes inhibit immune mediated phagocytosis of red blood cells

BACKGROUND

Patients having immune cytopenias produce antibodies that target hematopoietic cells resulting in their phagocytosis and intracellular destruction. Early reports suggested that phagocytosis could be inhibited by interfering with membrane thiol (SH) groups on phagocytes. Thus, whether chemical compounds that interact with SH or disulfide (SS) groups on mononuclear phagocytes can inhibit phagocytosis of antibody-coated cells was examined.

STUDY DESIGN AND METHODS

A monocyte monolayer assay (MMA), which examines the in vitro monocyte-macrophage (Mphi) interaction with anti-Rh(D)-coated red cells (RBCs), was used to study the ability of different SH and SS chemicals to inhibit the Fc receptor-mediated phagocytosis of sensitized RBCs. The compounds examined included thimerosal, dithiothreitol (DTT), pentane-1-thiol, and two recently described SH and two SS chemicals that have been synthesized.

RESULTS

All compounds were found to be able to inhibit phagocytosis to varying degrees correlating to the structure of the molecule. In general, those compounds that interact with free SH groups to inhibit phagocytosis were found better than SH-containing compounds that interact with SSs. Thimerosal and p-nitrophenyl methyl disulfide were the most effective compounds inhibiting phagocytosis. Both chemicals showed greater than 50 percent inhibition at concentrations as low as 10(-9) mol per L. DTT was the least effective compound tested. Only thimerosal showed significant toxicity, as determined by decreased cell viability and increased apoptosis, but only at concentrations of 10(-8) mol per L. The effect of chemical treatment was on attachment rather than on phagocytosis itself. Fcgamma receptor-independent endocytosis was not affected by the chemical treatment.

CONCLUSION

These studies indicate that pharmacologic strategies that target SH groups on mononuclear phagocytes may have future efficacy for the treatment of immune cytopenias.

Lactic acid triggers, in vitro, thiomersal to degrade protein in the presence of PLGA microspheres

Microspheres of polymers like poly(lactic-co-glycolic acid) (PLGA) have been studied as a vehicle for controlled release vaccines. They require materials and processes that might change the protein antigenicity. Lactic acid is produced during microsphere degradation that occurs in tandem with protein liberation. In addition, most of the proteins that have been used in microencapsulation studies contain Thimerosal((R))(TM) and this can introduce another undesirable effect for their stability. We demonstrated in vitro that the thiosalycilic acid (TSA), produced after the reduction of TM by lactic acid, reduces the S-S bridge of the previously incubated diphtheric toxoid (Dtxd). This reduction is immediately followed by blocking the two -SH formed by the same TSA molecules. In the light of these conclusions it is necessary now, to reinterpret the in vitro protein degradation-stabilization data in the presence of PLGA microspheres, mainly for those proteins which contain S-S. We propose that all the PLGA microspheres microencapsulation studies and protein structural considerations should be done in the absence of TM as preservative.

Thimerosal and the occurrence of autism: negative ecological evidence from Danish population-based data

OBJECTIVE

It has been suggested that thimerosal, a mercury-containing preservative in vaccines, is a risk factor for the development of autism. We examined whether discontinuing the use of thimerosal-containing vaccines in Denmark led to a decrease in the incidence of autism.

DESIGN

Analysis of data from the Danish Psychiatric Central Research Register recording all psychiatric admissions since 1971, and all outpatient contacts in psychiatric departments in Denmark since 1995.

PATIENTS

All children between 2 and 10 years old who were diagnosed with autism during the period from 1971-2000.

OUTCOME MEASURES

Annual and age-specific incidence for first day of first recorded admission with a diagnosis of autism in children between 2 and 10 years old.

RESULTS

A total of 956 children with a male-to-female ratio of 3.5:1 had been diagnosed with autism during the period from 1971-2000. There was no trend toward an increase in the incidence of autism during that period when thimerosal was used in Denmark, up through 1990. From 1991 until 2000 the incidence increased and continued to rise after the removal of thimerosal from vaccines, including increases among children born after the discontinuation of thimerosal.

CONCLUSIONS

The discontinuation of thimerosal-containing vaccines in Denmark in 1992 was followed by an increase in the incidence of autism. Our ecological data do not support a correlation between thimerosal-containing vaccines and the incidence of autism.

Neurodevelopmental disorders after thimerosal-containing vaccines: a brief communication

We were initially highly skeptical that differences in the concentrations of thimerosal in vaccines would have any effect on the incidence rate of neurodevelopmental disorders after childhood immunization. This study presents the first epidemiologic evidence, based upon tens of millions of doses of vaccine administered in the United States, that associates increasing thimerosal from vaccines with neurodevelopmental disorders. Specifically, an analysis of the Vaccine Adverse Events Reporting System (VAERS) database showed statistical increases in the incidence rate of autism (relative risk [RR] = 6.0), mental retardation (RR = 6.1), and speech disorders (RR = 2.2) after thimerosal-containing diphtheria, tetanus, and acellular pertussis (DTaP) vaccines in comparison with thimerosal-free DTaP vaccines. The male/female ratio indicated that autism (17) and speech disorders (2.3) were reported more in males than females after thimerosal-containing DTaP vaccines, whereas mental retardation (1.2) was more evenly reported among male and female vaccine recipients. Controls were employed to determine if biases were present in the data, but none were found. It was determined that overall adverse reactions were reported in similar-aged populations after thimerosal-containing DTaP (2.4 +/- 3.2 years old) and thimerosal-free DTaP (2.1 +/- 2.8 years old) vaccinations. Acute control adverse reactions such as deaths (RR = 1.0), vasculitis (RR = 1.2), seizures (RR = 1.6), ED visits (RR = 1.4), total adverse reactions (RR = 1.4), and gastroenteritis (RR = 1.1) were reported similarly after thimerosal-containing and thimerosal-free DTaP vaccines. An association between neurodevelopmental disorders and thimerosal-containing DTaP vaccines was found, but additional studies should be conducted to confirm and extend this study.

Impact of the thimerosal controversy on hepatitis B vaccine coverage of infants born to women of unknown hepatitis B surface antigen status in Michigan

OBJECTIVE

Hepatitis B vaccine is recommended for all infants, and the series may be started during the delivery admission. For infants who are born either to women who are positive for hepatitis B surface antigen (HBsAg) or to women whose HBsAg status is unknown, vaccination should be started within 12 hours of birth to prevent perinatal and early childhood hepatitis B virus infection. Because of concerns about mercury exposures from vaccines that contain thimerosal, the United States Public Health Service (USPHS) and the American Academy of Pediatrics (AAP) recommended in July 1999 that the first dose of hepatitis B vaccine be deferred until 2-6 months of age but only for infants who are born to HBsAg-negative women. To assess the impact on birth-dose vaccine coverage for infants who are born to women with unknown HBsAg status, we measured coverage before and after July 1999.

METHODS

A sample of Michigan infants who were born to women whose HBsAg status was either unknown or missing were identified by reviewing newborn screening cards for infants who were born during 1) March-April 1999 (before recommendation changes [T1]); 2) July 15-September 15, 1999 (immediately after recommendation changes [T2]); and 3) March-April 2000 (6 months after resumption of pre-1999 practices were recommended [T3]). We verified maternal HBsAg screening and newborn hepatitis B vaccination by reviewing infant and maternal hospital records.

RESULTS

Of 1201 infants who were born to women whose HBsAg status was indicated as unknown or missing on the newborn screening card during the 3 time periods, 216 (18%) were born to women whose status was truly unknown at the time of delivery, as determined by medical record review. During T1, 53% of these 216 infants received hepatitis B vaccine before hospital discharge, compared with 7% of infants who were born during T2 and 57% of infants who were born during T3. During T1, 19% of these infants received hepatitis B vaccine within 12 hours of birth compared with 1% of infants who were born during T2 and 14% of infants who were born during T3.

CONCLUSIONS

Hepatitis B vaccine birth-dose coverage for infants who were born to women whose HBsAg status was unknown at the time of delivery was already low in Michigan before the July 1999 USPHS/AAP Joint Statement but decreased significantly during the 2 months after the USPHS/AAP Joint Statement. Abrupt changes in established vaccination recommendations for lower risk children may lead to decreased coverage among higher risk children. Increases in hepatitis B vaccine coverage at birth are necessary to reduce the risk of perinatal infection for infants who are born to women with unknown HBsAg status.

A comparison of two different formulations of diclofenac sodium 0.1% in the treatment of inflammation following cataract-intraocular lens surgery

OBJECTIVE

To compare the efficacy, tolerability and local tolerance of diclofenac sodium 0.1% containing hydroxypropylgamma cyclodextrin preserved with benzalkonium chloride 0.005% (Voltaren Ophtha CD), with that of diclofenac sodium 0.1% preserved with thiomersal 0.004% (Voltaren Ophtha) in the treatment of inflammation after cataract-intraocular lens surgery.

DESIGN AND SETTING

Randomised 2:1, double-masked, parallel-group study in six centres in Germany.

STUDY PARTICIPANTS

299 patients scheduled to undergo phacoemulsification with posterior chamber intraocular lens implantation.

INTERVENTIONS

Study medications were instilled four times in the 30 minutes before surgery and four times daily from the first postoperative day.

MAIN OUTCOME MEASURES

The key efficacy variable was the reduction in anterior chamber flare (photons/millisecond) from day 1 to day 6 to 8. Patients underwent comprehensive ocular examinations, including laser flaremetry (KOWA), preoperatively and postoperatively at days 1, 6 to 8 and 24 to 32.

RESULTS

268 patients (Voltaren Ophtha CD 177, Voltaren Ophtha 91) completed the day 6 to 8 visit without any protocol violations. Reduction in the degree of intraocular inflammation with Voltaren Ophtha CD was equivalent to that achieved with Voltaren Ophtha at the day 6 to 8 [95% confidence interval (CI) -3.07 to +0.54] and day 24 to 32 (95% CI -1.44 to +1.40) visits. Although there was no significant (p = 0.464) difference between the two study groups in patients' global assessment of local tolerance at day 24 to 32, ocular discomfort was significantly (p = 0.023) less with Voltaren Ophtha CD compared with Voltaren Ophtha.

CONCLUSIONS

Voltaren Ophtha CD was as effective and well tolerated but had less ocular discomfort compared with Voltaren Ophtha in the treatment of ocular inflammation after phacoemulsification with intraocular lens implantation. This new formulation of diclofenac sodium 0.1% may be used as an alternative to the existing formulations of ophthalmic diclofenac sodium 0.1%.

A pilot scale evaluation of removal of mercury from pharmaceutical wastewater using granular activated carbon

Thimerosal (an organic mercury compound) is widely used in the pharmaceutical industry and hospitals. This study examines the removal of mercury (thimerosal and Hg(II)) from a pharmaceutical wastewater using F-400 granular activated carbon (GAC) at bench and pilot scales. Bench scale dynamic column tests are conducted with 30, 60, 90 and 120 min empty bed contact times (EBCTs). The pilot scale study is conducted using two GAC columns-in-series each of 30 min EBCT. The capital and operational cost analysis for the treatment system is performed. Simultaneous removal of copper, turbidity, phenol, and color from the wastewater by the pilot scale system is also reported.

Impact of the Joint Statement by the American Academy of Pediatrics/US Public Health Service on thimerosal in vaccines on hospital infant hepatitis B vaccination practices

OBJECTIVE

To determine the impact of the American Academy of Pediatrics/US Public Health Service (AAP/USPHS) joint statement on thimerosal in vaccines on hospital infant hepatitis B vaccination policies in Wisconsin.

METHODS

The nurse managers of hospital newborn nurseries (n = 110) were surveyed by mail. Nonresponders were resurveyed. Twelve hospitals no longer provided obstetric services. Of the remaining 98 hospitals, 84 (86%) responded to the initial mailing and 14 (14%) responded to the second mailing. The number of hospitals that offered hepatitis B vaccine to infants before July 1999 was compared with that in March 2000. The number of hospitals that had policies in place to vaccinate infants whose mothers' hepatitis B surface antigen status (HBsAg) was positive or unknown during the thimerosal alert (July 1999 through November 1999) was compared with that in March 2000.

RESULTS

Before July 1999, 81% of the hospitals representing 84% of reported Wisconsin births routinely offered hepatitis B vaccine to all infants. By March 2000, 50% of hospitals, representing 43% of births, had resumed routine infant hepatitis B vaccination. Physician decision to use a combination Haemophilus influenzae type b hepatitis B vaccine was the most frequently given reason for not reinstituting infant hepatitis B vaccination. During the thimerosal alert, 23% of hospitals did not have policies to vaccinate infants whose mothers were HBsAg-positive and 51% did not have policies to vaccinate infants whose mothers' HBsAg status was unknown. By March 2000, 6% of hospitals still did not have policies to vaccinate infants whose mothers were HBsAg-positive and 24% did not have policies to vaccinate infants whose mothers' HBsAg status was unknown.

CONCLUSION

The AAP/USPHS joint statement on thimerosal in vaccines has resulted in a 38% decrease in the number of hospitals routinely offering infants hepatitis B vaccine. Although thimerosal-free hepatitis B vaccine is now available, some hospitals still do not have appropriate policies in place for vaccinating infants whose mothers' HBsAg status is positive or unknown. In the future, policymakers should include anticipated consequences that may result from changes in immunization policy in their recommendations.

Vaccines Without Thiomersal

The inorganic mercurial thiomersal (merthiolate) has been used as an effective preservative in numerous medical and non-medical products since the early 1930s. Both the potential toxicity of thiomersal and sensitisation to thiomersal in relation to the application of thiomersal-containing vaccines and immunoglobulins, especially in children, have been debated in the literature. The very low thiomersal concentrations in pharmacological and biological products are relatively non-toxic, but probably not in utero and during the first 6 months of life. The developing brain of the fetus is most susceptible to thiomersal and, therefore, women of childbearing age, in particular, should not receive thiomersal-containing products. Definitive data of doses at which developmental effects occur are not available. Moreover, revelation of subtle effects of toxicity needs long term observation of children. The ethylmercury radical of the thiomersal molecule appears to be the prominent sensitiser. The prevalence of thiomersal hypersensitivity in mostly selected populations varies up to 18%, but higher figures have been reported. The overall exposure to thiomersal differs considerably between countries. In many cases a positive routine patch test to thiomersal should be considered an accidental finding without or, probably more accurately, with low clinical relevance. In practice, some preventive measures can be taken with respect to thiomersal hypersensitivity. However, with regard to the debate on primary sensitisation during childhood and renewed attention for a reduction of children's exposure to mercury from all sources, the use of thiomersal should preferably be eliminated or at least be reduced. In 1999 the manufacturers of vaccines and immunoglobulins in the US and Europe were approached with this in mind. The potential toxicity in children seems to be of much more concern to them than the hidden sensitising properties of thiomersal. In The Netherlands, unlike many other countries, the exposure to thiomersal from pharmaceutical sources has already been reduced. Replacement of thiomersal in all products should have a high priority in all countries.

Route of decomposition of thiomersal (thimerosal)

The route of formation and identification of the principal degradation products of thimerosal (thiomersal) has been undertaken. The initial oxidation to dithiosalicylic acid is followed by cleavage of the disulphide bond of the dithiosalicylic acid by the ethylmercuric ion to reform 1.5 mol of thimerosal with concurrent oxidation to form 0.5 mol of 2-sulfinobenzoic acid for each mole of dithiosalicylic acid. In the presence of copper ions 2-sulfobenzoic acid was also formed. A mechanism has been proposed which accounts for the stoichiometry of the cleavage reaction observed and the significance of the reaction is discussed.

Preserved solid lipid nanoparticles (SLN) at low concentrations do cause neither direct nor indirect cytotoxic effects in peritoneal macrophages

In order to investigate the interaction of preserved solid lipid nanoparticles (SLN) with murine peritoneal macrophages (Mpsi), cytotoxicity and proinflammatory effects of two different solid lipid nanoparticles (SLN) preparations consisting of either compritol (CO) or cetyl palmitate (CP) preserved with thiomersal were analyzed. Concentration-dependent cytotoxic effects were observed using the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay. Secretion of interleukin-6 by Mpsi following incubation with CO and CP SLN did not differ from secretion by untreated cells; proinflammatory cytokines interleukin-12 and tumor-necrosis-factor-alpha as further indicators of immunomodulatory effects were not detectable. These findings paralleled our previous findings that unpreserved CO and CP SLN did not induce immunomodulatory effects but cytotoxicity at higher concentrations. There were no synergistic cytotoxic effects of preservative and SLN. Thus, preservation of SLN using thiomersal does not appear to cause increased cytotoxicity and immunomodulatory effects following incubation with Mpsi.

Interference of thimerosal in the bicinchoninic acid protein microassay

In this investigation the total amount of protein present in the three influenza vaccine formulations Fluvirin, Fluzone and Flushield have been tested where thimerosal is present as a preservative. Interaction of thimerosal with protein has been confirmed by analysing ovalbumin as a control against ovalbumin-thimerosal solution. The results indicate that interference of thimerosal can be overcame for the quantitative assay of proteins by BCA technique with the good reproducibility. The present study identified also the degree of interference of thimerosal in the protein formulations and development of a method to nullify the interference by removing thimerosal.

Thimerosal positivities: the role of organomercury alkyl compounds

Contact allergy to thimerosal (TH) has not been considered a marker for mercury allergy, since there is a low degree of cross-sensitivity to inorganic as well as to organic mercury salts. 40 subjects, who previously gave a positive patch test reaction only to thimerosal 0.1% pet. (Hermal), when simultaneously repatch-tested to solutions containing TH, mersalyl acid, p-amino-phenylmercuric acid, mercuric acetate and thiosalicylic acid, respectively, gave positive reactions only to TH. 36 out of 40 subjects were divided into 2 groups of 18 subjects and simultaneously repatch-tested to solutions containing TH, methylmercury chloride (MeHgCl), thiosalicylic acid, and, ethylmercury chloride (EtHgCl), respectively. EtHgCl was tested in the 1st group at 0.031% and in the 2nd group at 0.015%. The results showed that all subjects gave concomitant positive reactions to TH, EtHgCl and MeHgCl. EtHgCl 0.031% gave a higher number of reactions than EtHgCl 0.015%, underlining the rôle of the solvent in these reactions. Patch test results in 300 consecutive patients to a standard series, to which MeHgCl was added, showed that MeHgCl and TH were never able to give isolated positive reactions, and that the concomitant positive reactions occurred in only 3.6% of subjects. In conclusion, our data seem to suggest that the positive reactions to TH found in our patients were due to EtHgCl, and that the structural similarities with MeHgCl were so close that the skin reacted against each as if they were identical.

Hypersensitivity to thimerosal: the sensitizing moiety

There has been increasing interest in characterizing the sensitizing moiety of thimerosal [TIM], following the finding that patients with photosensitivity to piroxicam are allergic to the thiosalicylic acid [TIO] moiety of TIM. For this purpose, the authors have conducted 2 studies in TIM-sensitive patients. In the 1st, of 175 patients tested with TIO and ammoniated mercuric chloride [HGAM], 45.7% reacted only to TIM, whereas 45.7% reacted also to TIO and 17.7% also to HGAM; 9.1% reacted to both TIO and HGAM. In the 2nd, of 47 patients tested with TIO and ethylmercuric chloride [ETHG], 87.2% reacted to ETHG, 44.7% to TIO and 31.9% reacted to both. None of the patients reacted only to TIM. The authors conclude that thimerosal allergy is due either to the mercuric moiety or to thiosalicylic acid, with no cases of sensitivity only to the whole molecule of TIM. TIM-sensitive patients are mainly allergic to the mercuric moiety, but among them there are a large number of TIO-sensitive patients, and these should be advised to avoid piroxicam.

Evaluation of the capability of different chromatographic systems for the monitoring of thimerosal and its degradation products by high-performance liquid chromatography with amperometric detection

Several liquid chromatographic systems using electrochemical detection on carbon electrodes were compared for the analysis of thimerosal and its degradation products, thiosalicylic acid and dithiodibenzoic acid. The studied separation systems included reversed-phase ion-suppressed chromatography, reversed-phase ion-pair chromatography and ion chromatography. Amperometry and coulometry were evaluated as electrochemical detection techniques. The best method for thimerosal determination in ophthalmic solutions in terms of selectivity and sensitivity was ion-pair chromatography.

High performance gel filtration using monodisperse highly cross-linked agarose as a one-step system for mucin purification

High performance gel filtration on monodisperse cross-linked agarose (Superose 6) has been assessed as a system for purification of mucus glycoproteins. Comparison with the conventional two-step purification of mucus glycoprotein by Sepharose CL4B gel filtration followed by caesium chloride density gradient centrifugation shows that purification by high performance gel filtration is at least as thorough, yielding mucin that is free from non-mucin glycoproteins as defined by buoyant density, mobility on sodium dodecyl sulphate-polyacrylamide gel electrophoresis and absence of Concanavalin A binding (mannose-containing) material. This technique allows mucus glycoprotein to be purified from lyophilized crude mucin in 120 min compared with approximately 72 h using the conventional techniques. This makes the comparative study of mucus glycoprotein changes in disease states much more feasible.

Sensitivity to thimerosal and photosensitivity to piroxicam

17 patients allergic to thimerosal, with no previous history of photosensitivity or piroxicam ingestion, 2 patients with piroxicam-induced photosensitivity, and 10 controls were patch or photopatch tested, with 1 or more of the following: thimerosal, thiosalicylic acid, irradiated and non-irradiated solutions of piroxicam alone, L-cysteine alone and piroxicam plus L-cysteine, and piroxicam in petrolatum., The results of the tests supported the hypothesis that there are cross-reactions between thiosalicylic acid and prioxicam, a photosensitizer. The mechanism of the cross-reactions may involve photoproducts of piroxicam and L-cysteine, as patients allergic to thiosalicylic acid, who have positive photopatch tests to piroxicam, also had positive patch tests to the irradiated solution of piroxicam plus L-cysteine.

A probable role for vaccines containing thimerosal in thimerosal hypersensitivity

We patch tested 141 patients with 0.05% aq. thimerosal and 222 patients with 0.05% aq. mercuric chloride, including 63 children. The frequency of positive patch test reactions to thimerosal was 16.3%. There was a marked preponderance in the young age groups after vaccination, while none of 36 infants (aged 3-48 months) reacted to thimerosal. Positive reactions to mercuric chloride were found in 23 (10.4%) of 222 patients. We also sensitized guinea pigs with diphtheria-pertussis-tetanus (DPT) vaccine containing 0.01% thimerosal and succeeded in inducing hypersensitivity to thimerosal. From patch testing in humans and animal experiments, it is suggested that 0.01% thimerosal in vaccines can sensitize children, and that hypersensitivity to thimerosal is due to the thiosalicylic part of the molecule and correlates with photosensitivity to piroxicam.