Effects of sodium methyldithiocarbamate on selected parameters of innate immunity and clearance of bacteria in a mouse model of sepsis.

AIMS: Sodium methyldithiocarbamate (SMD), the third most widely used conventional pesticide in the United States, has been reported to inhibit several parameters associated with inflammation and to decrease resistance to infection. In a previous study, survival time was markedly decreased when mice were treated orally with SMD shortly before challenge with a high dose of Escherichia coli (E. coli) that was lethal to most of the control mice. In the present study, we evaluated selected parameters of the innate immune system using a lower challenge dose of E. coli, to determine which (if any) of these parameters reflected continued changes through 24h. MAIN METHODS: Bacterial clearance from the peritoneal cavity, production of chemokines and cytokines, and body temperature were measured. KEY FINDINGS: All these parameters were reduced by SMD up to 12h after bacterial challenge, but the concentration of the anti-inflammatory cytokine IL-10 was increased. Even so, mice in the control and SMD-treated groups cleared most bacteria by 24h. Other parameters (cytokine concentrations and body temperature) were also normal or near normal by 24h. The same dosage of SMD administered intranasally also did not significantly decrease survival. Hypothermia from 16 to 28 h correlated with lethal outcome, but SMD significantly increased hypothermia only at 2 and 4h after challenge. SIGNIFICANCE: In spite of substantial early inhibition by SMD of parameters known to be important for resistance to infection, bacterial clearance and survival were not altered, suggesting immunological reserve and/or rapid recovery after transient effects of SMD.

Reaction profile in patch testing with allergens formed during vulcanization of rubber.

BACKGROUND: Vulcanization of rubber changes its allergen pattern. OBJECTIVES: To estimate the contact allergic reactivity profile of users of finished rubber products. METHODS: Twenty-four patients with known contact allergy to rubber accelerators were patch tested with 21 compounds found in chemical analyses of vulcanized rubber products. No diphenylguanidine, p-phenylenediamine antioxidants or thioureas were included in the study. RESULTS: Thiuram monosulfides formed during vulcanization showed generally stronger test reactions than the corresponding thiuram disulfides. We also obtained more positive thiuram reactions to the monosulfides than to the disulfides. A positive reaction to a dithiocarbamate was accompanied by a positive reaction to the corresponding thiuram, except for 1 patient. The nitrogen substituents showed only minor differences between the methyl, ethyl and pentamethylene groups, but the butyl derivatives gave, in most cases, a negative response. Dialkylthiocarbamyl benzothiazole sulfides, formed between thiurams and mercaptobenzothiazoles during vulcanization, showed strong test reactions in almost all patients who were sensitive to dithiocarbamates, thiurams, or mercaptobenzothiazoles. CONCLUSIONS: We found thiuram monosulfides to be better markers of thiuram sensitivity than the corresponding disulfides or dithiocarbamates. Surprisingly, the dialkylthiocarbamyl benzothiazole sulfides were good markers of both thiuram and mercaptobenzothiazole sensitivity. This is an unexpected finding that needs to be confirmed in a larger study.

Ultra-sensitive electrochemical immunosensor using analyte peptidomimetics selected from phage display peptide libraries.

Immunosensors for small analytes have been a great addition to the analytical toolbox due to their high sensitivity and extended analytical range. In these systems the analyte is detected when it competes for binding to the detecting antibody with a tracer compound. In this work we introduce the use of phage particles bearing peptides that mimic the target analyte as surrogates for conventional tracers. As a proof of concept, we developed a magneto-electrochemical immunosensor (EI) for the herbicide molinate and compare its performance with conventional formats. Using the same anti-molinate antibody and phage particles bearing a molinate peptidomimetic, the EI performed with an IC(50) of 0.15 ngmL(-1) (linear range from 4.4 × 10(-3) to 10 ngmL(-1)). Compared to the conventional ELISA, the EI was faster (minutes), performed with a much wider linear range, and the detection limit that was 2500-fold lower. The EI produced consistent measurements and could be successfully used to assay river water samples with excellent recoveries. By using the same EI with a conventional tracer, we found that an important contribution to the gain in sensitivity is due to the filamentous structure of the phage (9 × 1000 nm) which works as a multienzymatic tracer, amplifying the competitive reaction. Since phage-borne peptidomimetics can be selected from phage display libraries in a straightforward systematic manner and their production is simple and inexpensive, they can contribute to facilitate the development of ultrasensitive biosensors.

Modulation of endothelial monolayer permeability induced by plasma obtained from lipopolysaccharide-stimulated whole blood.

The aim of this study was to elucidate the time course of the permeability response of endothelial monolayers after exposure to plasma obtained from lipopolysaccharide (LPS)-treated human whole blood; to investigate the role of apoptosis in monolayer permeability, and to inhibit the permeability increase, particularly after addition of the plasma stimulus. Human umbilical vein endothelial cells (HUVEC) were cultured on semiporous membranes and the permeability for albumin was measured after exposure, according to different schedules, to LPS-conditioned plasma. Apoptotic HUVEC were measured by both flow cytometry and ELISA. A variety of agents, including antibodies against cytokines, inhibitors of NF-kappaB, and a caspase inhibitor, were added to HUVEC, either prior to or after the stimulus. A maximum increase of the permeability was achieved after 4-6 h of exposure to LPS-conditioned plasma. This response was not accompanied by an increase in the number of apoptotic HUVEC. Administration of antibodies against both Tumour Necrosis Factor-alpha (TNF-alpha) and Interleukin-1beta (IL-1beta) to HUVEC within 1 h after stimulation significantly reduced the permeability increase. Similarly, pyrollidine di-thiocarbamate (PDTC), but not N-acetylcysteine, could prevent the permeability response, and was still effective when added within 2 h after LPS-conditioned plasma. The TNF-alpha/IL-1beta signal present in LPS-conditioned plasma appears to increase endothelial permeability through intracellular pathways that very likely involve the activation of NF-kappaB. Although poststimulatory inhibition of the permeability response proves to be possible with agents such as PDTC, the window of opportunity appears very small if placed in a clinical perspective.

The British standard series of contact dermatitis allergens: validation in clinical practice and value for clinical governance.

BACKGROUND: All centres use an empirically determined set of 'standard' test allergens for patch testing that contain the commoner environmental sensitizers. Objectives To assess the validity of the British standard series of 12 allergens used in addition to the 23 already in the European standard series. PATIENTS AND METHODS: Results for 3062 consecutive patients patch tested in seven centres across the United Kingdom during the year 2000 were analysed. RESULTS: The additional allergens from the British series and positive rates were: methyl dibromoglutaronitrile 2.4%, carba mix 1.6%, tixocortol pivalate 1.5%, ethylenediamine 1.3%, cetearyl alcohol 0.8%, 2-bromo-2-nitropane-1,3-diol 0.8%, diazolidinyl urea 0.7%, chlorocresol 0.6%, budesonide 0.6%, fusidic acid 0.5%, imidazolidinyl urea 0.5%, and chloroxylenol 0.4%. The allergens with the lowest positive rate in the European standard series were primin at 0.6% and isopropyl-phenyl-para-phenylenediamine at 0.4%. CONCLUSIONS: The 12 allergens in the British series should continue being tested as a standard addition to the European series within the U.K. The collection of data in this manner to allow comparisons between centres shows differences that reflect selection criteria and interpretation of results, and offers a useful tool for audit and clinical governance. Testing fewer than 1 : 2150 population may indicate underprovision of service. Similarly, rates of sensitization for nickel contact allergy above 26% and for fragrance mix above 16% (the upper 95% confidence intervals) should stimulate inquiry into the reasons behind this.

Patch testing discordance alert: false-negative findings with rubber additives and fragrances.

From July 1996 through June 1998, the North American Contact Dermatitis Group evaluated 318 patients for suspected contact dermatitis by patch testing simultaneously with Finn Chambers and the T.R.U.E. Test allergen system. Discrepancies between the two systems were found in some of the results, particularly with fragrance and rubber allergens. These results suggest that positive reactions to fragrance, thiuram, and carba mix allergens may be missed if the T.R.U.E. Test is used alone.

A novel fibrillar structure in cultured cells detected by a monoclonal antibody.

Using a monoclonal antibody, we have detected an antigen present in a unique fibrillar structure in the cytoplasm of cultured cells by immunofluorescence. These structures have been identified by transmission electron microscopy and ultrastructural immunocytochemistry as large single paracrystalline arrays of individual filaments morphologically similar to intermediate filaments. The antibody detects these structures in fibroblastic and epithelioid cultured cell lines of mouse, rat, bovine, and human origin but not of avian origin. Only a small percentage of the cells in a culture contains these structures; each cell usually contains only one, although two or more have been observed in a single cell. The structures are elongated vermiform arrays of filaments in the cytoplasm (approximately 0.5 X 3 microns) which have a thread-like or toroidal appearance. Because of this shape, we have named the putative antigen recognized by this antibody "nematin." Double-label experiments showed that these structures had no relationship to tubulin or vimentin. Immunocytochemical localization in human tissues revealed a high concentration of a reactive antigen in the stratum granulosum of skin and in what probably are neuroglial cells in the central nervous system. This monoclonal antibody may detect a novel intermediate filament protein and/or a shared determinant of different intermediate filament proteins.

The problem of the sensitization to dithiocarbamates in thiuram-allergic patients.

Because of the occurrence of hand dermatitis in members of a surgical staff due to allergy to thiuram-containing rubber gloves, an investigation was performed about cross-sensitization between thiuram compounds and dithiocarbamates. Positive reactions to dithiocarbamates were compared with reactions to 8 brands of hypo-allergenic or dithiocarbamate-containing surgical gloves. There appeared to be a marked difference in reactions to the dithiocarbamate-containing gloves. Some brands gave negative or nearly always negative reactions, while other brands caused many positive reactions. Thiuram-allergic patients were advised to wear nonreacting rubber gloves or PVC gloves.