A study of the Effects of Angiotensins 1, 2, 3 and Bradykinin on the Replication of Bovine Retinal Capillary Endothelial Cells and Pericytes

The renin-angiotensin system of the human eye may play a role in the regulation of retinal blood flow and the development of new vessels. We have investigated whether angiotensins 1, 2 and 3 or bradykinin, in concentrations ranging between 1 × 10–12 and 1 × 10–6, have any mitogenic activity on cultured bovine retinal endothelial cells (BREC) and pericytes (BRP). Cell replication was assessed by 3H-thymidine incorporation and, in the case of BREC and A T-2, also by cell counts. A T-2 was also tested on bovine aortic EC (BAEC). None of the substances elicited any response on BREC, BRP or BAEC. Whether angiotensin(s) induce angiogenesis in retinal vessels in vivo remains to be established but this does not appear to occur through direct stimulation of cell replication.

Steady-state pharmacokinetics of hydroxychloroquine in patients with cutaneous lupus erythematosus

Background Hydroxychloroquine (HCQ), a 4-aminoquinolone antimalarial, is regarded as the oral therapy of choice for cutaneous and systemic lupus erythematosus (SLE). It is also licensed for rheumatoid arthritis (RA). Studies of HCQ-treated patients with SLE or RA have demonstrated a positive correlation between whole-blood HCQ levels and clinical response. Such studies have involved measuring whole-blood concentrations at any given time point after HCQ ingestion assuming that steady-state concentrations would undergo limited fluctuation over a daily interval because HCQ has a long half-life. This approach might not sufficiently take into account the potential intra-patient variation in HCQ blood levels that can occur over a 24-hour period. Such variation, if significant, could affect the credibility of any concentration-response relationship provided from these previous studies. Objectives The objectives of this report are to: (a) investigate the intra-patient variation in HCQ whole-blood levels and (b) suggest an optimum time for sampling patients for future studies. Methods Six patients were recruited with cutaneous lupus erythematosus who had each been on HCQ 200 mg twice daily for at least six months, so that they were at steady-state. Each patient was fasted overnight and had standardized meals and dosing schedule. Whole blood was sampled at seven time points over 24 hours. Whole-blood HCQ levels were measured with high-performance liquid chromatography using gradient elution, fluorimetric detection and chloroquine as an internal standard. The assay had a mean inter- and intra-day coefficient of variation of 10% and 5% respectively and a limit of detection of 5ng/ml. Results HCQ levels appeared to follow a biphasic pattern over the sampling period. Maximum levels were noted a median of four hours (range 2-6) after ingestion. Median intra-patient variation between trough and peak levels, 'Cmax' ((peak - trough)/trough × 100%), was 27% (range 8-150%). Conclusions This study demonstrated that whole-blood HCQ levels vary 27% (median, range 8-150%) within an individual over a 12-hour period. Drug levels might differ between individuals because of multiple factors, including variable adherence to medication. Measuring HCQ levels for assessment of drug adherence could be valuable in the 'real-world' clinical setting. This could be assessed by taking a blood sample at any time following HCQ ingestion. If patients were found to have very low or undetectable levels of HCQ, non-adherence to HCQ should be suspected.

Interindividual Variations in Enzymes Controlling Organophosphate Toxicity in Man

1 Interindividual variations in an unexposed population have been defined for five enzymes involved in organophosphate (OP) toxicity. The enzymes measured were: red blood cell acetylcholinesterase (AChE), lymphocyte neuropathy target esterase (NTE), serum cholinesterase (ChE), serum paraoxonase and serum arylesterase.

2 AChE and arylesterase were normally distributed in the population whilst the distribution of NTE, ChE and paraoxonase deviated significantly from normal.

3 Assay precision and intra-individual variability were measured for each of the enzymes; the effect on interindividual variation was assessed.

4 Variations in enzyme activities between individuals could have profound effects on susceptibility to OP toxicity. Prior determination of these enzymes may be predictive of susceptibility.

5 Lymphocyte NTE has some limitations as an indicator of exposure to neurotoxic OPs.

Effective measurement of knee alignment using AP knee radiographs

The gold standard for measuring knee alignment is mechanical axis determined using full-limb radiographs (FLR). Measurement of joint alignment using antero-posterior (AP) knee radiographs is more accessible, economical and involves less radiation exposure to the patient compared with using full-limb radiographs. The aim of this study was to compare and assess the reproducibility of knee joint axial alignment on full-limb radiographs and conventional AP knee radiographs. Knee alignment was measured in 40 subjects (80 knees) from the TwinsUK registry. Measurement of mechanical knee alignment was from FLR, and anatomic knee alignment from weight-bearing AP knee radiographs. Reproducibility was assessed by intra-class correlation coefficients and kappa statistics. Reproducibility of knee alignment for both methods was good, with intra-observer ICC's of 0.99 for both FLR and AP radiographs. The mean alignment angle on FLR was 178.9 degrees (SD 2.1, range 173-183 degrees ), and 179.0 degrees (SD 2.1, range 173-185 degrees ) on AP films. 58.8% of knees on FLR and 66.3% on AP films were of varus alignment. Good correlations were seen between results for FLR and AP radiographs, with ICC ranging from 0.87-0.92 for left and right knees, and kappa statistics of 0.65-0.74. Standard AP knee radiographs can be used to measure knee alignment with good reproducibility, and provide comparable results to those obtained from FLR. This will facilitate measurement of knee alignment in existing cohort studies to assess malalignment as a risk factor of incident OA, and in clinical practice.

Potential for metabolism locally in the skin of dermally absorbed compounds

Dermally absorbed chemicals can be locally metabolized in the skin during absorption but it is difficult to distinguish this metabolism from liver metabolism by biological monitoring in vivo. Studies with sub-cellular fractions have showed the presence of metabolizing enzymes in the skin but with loss of cellular localization. Studies in HaCat cells in culture maintain cellular localization and in skin, in short-term culture, the chemical can be applied to the skin surface and metabolism during absorption can be monitored. Flow though diffusion systems with tissue culture medium as receptor fluid have maintained the viability of skin and supported metabolism, but dilution of the metabolites in the receptor fluid has limited detection. This article uses data derived by a range of techniques from the Newcastle laboratory to discuss the importance of local metabolism in the skin of butoxyethanol to butoxyacetic acid and parabens to p-hydroxybenzoic acid during dermal absorption, following application to the skin surface.

The use of anti-tumour necrosis factor therapy in HIV-positive individuals with rheumatic disease

OBJECTIVE

The purpose of this study was to examine the safety and efficacy of anti-tumour necrosis factor (TNF) agents (etanercept, infliximab and adalimumab) in HIV-positive patients with rheumatic diseases refractory to standard therapy.

METHODS

Patients were treated with anti-TNF blocker with rheumatic diseases refractory to disease modifying antirheumatic drugs who had a CD4 count of >200 mm3 and an HIV viral load of <60 000 copies/mm3 and no active concurrent infections. Changes in CD4 counts, HIV viral loads, or other adverse effects while on anti-TNF agents and clinical response were monitored for 28.1 (SD 20.9) months (range 2.5-55).

RESULTS

Eight HIV-positive patients were treated with anti-TNF blockers (two patients with rheumatoid arthritis, three with psoriatic arthritis, one with undifferentiated spondyloarthritis, one with reactive arthritis and one with ankylosing spondylitis). No significant clinical adverse effect was attributed to this treatment in any patient. CD4 counts and HIV viral load levels remained stable in all patients. Three patients on etanercept therapy and two patients on infliximab had sustained clinical improvement in their rheumatic diseases.

CONCLUSIONS

This retrospective series of eight patients suggests that treatment with anti-TNF-alpha therapy is a viable alternative in HIV patients without advanced disease with associated rheumatic diseases refractory to standard therapy.

Inter‐ and intralaboratory variation of in vitro diffusion cell measurements: An international multicenter study using quasi‐standardized methods and materials

In vitro measurements of skin absorption are an increasingly important aspect of regulatory studies, product support claims, and formulation screening. However, such measurements are significantly affected by skin variability. The purpose of this study was to determine inter- and intralaboratory variation in diffusion cell measurements caused by factors other than skin. This was attained through the use of an artificial (silicone rubber) rate-limiting membrane and the provision of materials including a standard penetrant, methyl paraben (MP), and a minimally prescriptive protocol to each of the 18 participating laboratories. "Standardized" calculations of MP flux were determined from the data submitted by each laboratory by applying a predefined mathematical model. This was deemed necessary to eliminate any interlaboratory variation caused by different methods of flux calculations. Average fluxes of MP calculated and reported by each laboratory (60 +/- 27 microg cm(-2) h(-1), n = 25, range 27-101) were in agreement with the standardized calculations of MP flux (60 +/- 21 microg cm(-2) h(-1), range 19-120). The coefficient of variation between laboratories was approximately 35% and was manifest as a fourfold difference between the lowest and highest average flux values and a sixfold difference between the lowest and highest individual flux values. Intralaboratory variation was lower, averaging 10% for five individuals using the same equipment within a single laboratory. Further studies should be performed to clarify the exact components responsible for nonskin-related variability in diffusion cell measurements. It is clear that further developments of in vitro methodologies for measuring skin absorption are required.

In vitro predictions of skin absorption of caffeine, testosterone, and benzoic acid: a multi-centre comparison study

To obtain better insight into the robustness of in vitro percutaneous absorption methodology, the intra- and inter-laboratory variation in this type of study was investigated in 10 European laboratories. To this purpose, the in vitro absorption of three compounds through human skin (9 laboratories) and rat skin (1 laboratory) was determined. The test materials were benzoic acid, caffeine, and testosterone, representing a range of different physico-chemical properties. All laboratories performed their studies according to a detailed protocol in which all experimental details were described and each laboratory performed at least three independent experiments for each test chemical. All laboratories assigned the absorption of benzoic acid through human skin, the highest ranking of the three compounds (overall mean flux of 16.54+/-11.87 microg/cm(2)/h). The absorption of caffeine and testosterone through human skin was similar, having overall mean maximum absorption rates of 2.24+/-1.43 microg/cm(2)/h and 1.63+/-1.94 microg/cm(2)/h, respectively. In 7 out of 9 laboratories, the maximum absorption rates of caffeine were ranked higher than testosterone. No differences were observed between the mean absorption through human skin and the one rat study for benzoic acid and testosterone. For caffeine the maximum absorption rate and the total penetration through rat skin were clearly higher than the mean value for human skin. When evaluating all data, it appeared that no consistent relation existed between the diffusion cell type and the absorption of the test compounds. Skin thickness only slightly influenced the absorption of benzoic acid and caffeine. In contrast, the maximum absorption rate of testosterone was clearly higher in the laboratories using thin, dermatomed skin membranes. Testosterone is the most lipophilic compound and showed also a higher presence in the skin membrane after 24 h than the two other compounds. The results of this study indicate that the in vitro methodology for assessing skin absorption is relatively robust. A major effort was made to standardize the study performance, but, unlike in a formal validation study, not all variables were controlled. The variation observed may be largely attributed to human variability in dermal absorption and the skin source. For the most lipophilic compound, testosterone, skin thickness proved to be a critical variable.

Peripheral cholinesterase inhibition by occupational chlorpyrifos exposure in Australian termiticide applicators

Occupational exposure to organophosphorus insecticides (OPs), such as chlorpyrifos, may be monitored by the measurement of the activity of peripheral cholinesterase (ChE) enzymes, including erythrocyte acetylcholinesterase (EAChE) and serum cholinesterase (SChE). Lymphocyte neuropathy target esterase (NTE) is thought to have potential as a predictor of organophosphate-induced delayed neuropathy (OPIDN). This paper describes work performed in 39 Australian pest control operators (PCOs) exposed to a termiticide containing chlorpyrifos, and 34 unexposed control subjects. EAChE activities in PCOs did not differ from those of unexposed control workers. Mean NTE activity was slightly higher in PCOs than in controls and mean SChE was 52% of control activity. These results indicate that exposure of Australian PCOs to termiticides containing chlorpyrifos may be monitored using SChE but not EAChE or NTE, and that workers in this industry have sufficiently high OP exposure to significantly depress SChE activity. SChE inhibition of 70-80% may be associated with symptoms. Although no current symptoms were reported to be associated with occupational OP exposure, these workers may be at increased risk of acute effects following inadvertent spills or self-contamination due to their background level of exposure to OPs. While it is preferable to compare ChE enzyme activities between pre- and post-exposure periods to evaluate OP-related effects in individuals, in some cases there is an absence of pre-exposure data. The results of this study suggest that a screening value for SChE of 550 nmol/min/ml in a single blood sample may be useful to identify potentially OP-exposed individuals in the Australian population. Australian control subjects were similar with respect to EAChE, but displayed activities of NTE and SChE approximately 50 and 23% lower than an unexposed UK reference group. While these comparisons are presently speculative, they suggest that there may be differences in SChE and NTE activities in control populations of the two countries. The routine treatment of Australian homes with termiticides containing OPs, or differences in the availability and use of domestic OP-containing insecticides may explain these population differences. Further work is required to examine whether these differences are real, and if so their likely cause.

Cytogenetic response without changes in peripheral cholinesterase enzymes following exposure to a sheep dip containing diazinon in vivo and in vitro

Occupational exposure to organophosphorus insecticides (OPs), such as diazinon, may be monitored by the measurement of the activity of peripheral cholinesterase enzymes, including erythrocyte acetylcholinesterase (EAChE) and plasma or serum cholinesterase (plasma or serum ChE). Exposures have also been measured by the analysis of dialkyl phosphate metabolites of OPs in urine. The potential health risks associated with exposure, especially those of a neurological nature, may then be estimated, and appropriate measures to reduce or eliminate exposures can be implemented. There is evidence that some OP pesticides may have in vivo genotoxic effects, suggesting a possible link with cancer with long term or repeated heavy exposures. This paper describes work performed in 17 subjects with a single or two exposures to a sheep dip containing diazinon. Urine samples revealed OP metabolites dimethylphosphate (DMP), dimethylthiophosphate (DMTP), diethylphosphate (DEP) and diethylthiophosphate (DETP) in 37% of subjects at low levels which were not elevated after exposure. EAChE and plasma ChE were also unchanged before and after exposure, and were similar to those measured in unexposed control groups. Sister chromatid exchanges (SCE), a marker of chromosome damage, was significantly elevated in peripheral blood lymphocytes after exposure compared with before. SCE were unchanged in a group of non-occupationally exposed workers. In vitro studies with both authentic diazinon (98%) and diazinon in a sheep dip formulation (45%) showed increased SCE and decreased replicative indices, suggesting toxic and genotoxic effects of diazinon.

Systemic endothelial cell markers in primary antiphospholipid syndrome

The pathogenic mechanism underlying the prothrombotic tendency of Hughes' or antiphospholipid syndrome (APS) has not been elucidated. Numerous procoagulant mechanisms have been tested including platelet activation, monocyte tissue factor (TF) expression and endothelial cell (EC) activation. There is some evidence for the latter from studies on cultured human umbilical vein endothelial cells (HUVEC). Incubation with antiphospholipid antibodies (aPL) induces EC activation in vitro. We investigated whether there was evidence of EC perturbation in vivo using enzyme-linked immunosorbant assays (ELISAs) for soluble markers of EC dysfunction. Serum and plasma were collected from controls and patients with primary APS and ELISAs performed to quantify soluble vascular cell adhesion molecule (sVCAM), soluble intercellular adhesion molecule-1 (sICAM-1), interleukin-6 (IL-6), endothelin-1 (ET-1), von Willebrand factor (vWF) and soluble tissue factor (sTF). In addition, soluble p-selectin (p-selectin) and vascular endothelial growth factor (VEGF) were measured: the former as a marker of platelet activation, the latter as a potential mediator of TF expression. No significant differences in the levels of blood-borne soluble markers were detected between the patient and control groups except for VEGF and sTF, patients having significantly higher levels of VEGF and sTF than controls (p <0.05). These results suggest plasma soluble tissue factor and VEGF may play a role in the pathogenesis of thrombosis in APS, although the cell of origin of these molecules remains unclear.

Percutaneous absorption and metabolism of dinitrochlorobenzene in vitro

Dinitrochlorobenzene (DNCB) absorption through mouse and rat dorsal skin, pig ear skin and human abdominal skin in vitro was determined, and local metabolism to the glutathione conjugate was related to glutathione transferase activities and glutathione status in the skin. Absorption studies were conducted using skin mounted in a flow-through diffusion cell with tissue culture medium as receptor fluid. DNCB applied to the surface of skin in acetone penetrated through 26-day-old rat skin better than through the skin of the other species investigated. The amounts of absorption through pig and human skin and conjugation formation were similar. In general, occlusion resulted in increased penetration of DNCB but no change in conjugation. Human skin showed the highest gluta-thione-S-transferase activity towards DNCB, followed by 26-day-old rat, pig, mouse and neonatal rat skin. Levels of glutathione were highest in mouse skin, followed by neonatal rat, 26-day-old rat, pig and human skin, with pig and human skin showing similar levels. These studies indicated that the glutathione level in skin was the determining factor influencing the degree of DNCB conjugation during percutaneous absorption, and this was greatly depleted during percutaneous penetration of DNCB.

Electrophysiological and biochemical effects of single and multiple doses of the organophosphate diazinon in the mouse

Diazinon is an organophosphorus compound (OP) widely used in pesticides. The relationship between dose of diazinon, inhibition of acetylcholinesterase, and effect on neuromuscular transmission has been studied in a mouse model. Inhibition of acetylcholinesterase activity occurred within 1 h, was maximal by 3 h and remained inhibited for at least 24 h. Blood, brain, diaphragm, and soleus acetylcholinesterase activities were differentially affected by diazinon. Brain and soleus activities were not affected by low doses. Multiple daily dosing of diazinon caused a cumulative decrease in acetylcholinesterase activity, although to a lesser extent in brain and soleus. Diazinon had no effect on the activity of neuropathy target esterase. Plasma and brain levels of diazinon peaked at 15 min after dosing and declined with a half-life of 2.5 h. Metabolic products of diazinon were cleared from the urine within 24 h. Increased miniature end-plate current half decay times occurred in a dose-dependent manner. Single doses of diazinon caused an increase in the jitter (variability of latencies) of evoked action potentials recorded in the diaphragm but did not affect end-plate potential (EPP) jitter. Multiple lower doses of diazinon caused an increase in EPP jitter after 28 days. This effect on nerve function was delayed and occurred when acetylcholinesterase activity had returned to control levels. The results indicate that diazinon produces long-term electrophysiological changes in neurotransmission following repeated dosing in the mouse. This has implications for the current use of diazinon; however, there is a need to further define the mechanism of this effect.

Biomechanical performance of orthopedic gloves

The purpose of this study was to compare the biomechanical performance of commercially available orthopedic gloves to that of a single surgical glove, as well as a double glove system. The orthopedic gloves were found to be thicker than the single surgical glove. This increased thickness of the orthopedic glove was associated with a greater resistance to glove puncture. The thickest orthopedic gloves also had reduced tactile sensitivity when compared to the single surgical glove. In addition, the glove donning forces and glove hydration rates varied considerably. These latter biomechanical performance parameters were not significantly related to glove thickness. The double glove systems tested in this study had similar performance characteristics in regard to many of the orthopedic gloves. The glove donning forces for the double glove systems were the lowest of the gloves tested. In addition, the double glove systems displayed the greatest resistance to glove hydration of the gloves tested. Their performance in the glove hydration tests and the force required to don the double glove systems were much more desirable than any of the orthopedic gloves. The results of this study indicate that the double glove systems may provide a desirable alternative to the use of the single orthopedic gloves.

Failure of a new double glove hole detection system in the Emergency Department

The purpose of this study was to evaluate the performance of a new double glove hole detection system in the Emergency Department. First, the frequency of holes in both gloves of the double glove hole detection system was determined using a watertight test method. Second, the frequency of glove puncture was determined first by searching for the optical color change that occurs with the ingress of fluid in the double glove hole detection system. These same gloves were then removed and also checked for holes by the watertight test method. After removal from the package, no holes were detected in the two gloves of the system using the watertight test method. In 50 consecutive patients, there was no color change in the inner glove indicating glove puncture. When these same gloves were then tested with the watertight test method, 14 of the 50 double glove hole detection systems failed; all 14 outer gloves were punctured, and three of the inner gloves had holes without demonstrable injury to the skin. This double glove hole detection system is not a reliable system to detect holes in relatively dry clinical settings because the ingress of fluid by capillary action between the gloves is necessary to cause a color change in the inner glove that signals the presence of a hole.

Percutaneous penetration and dermal metabolism of triclosan (2,4, 4'-trichloro-2'-hydroxydiphenyl ether)

triclosan is widely used in many products that contact the skin of consumers. This study compares in vivo and in vitro skin absorption of triclosan and determines the potential of skin to metobolize it prior to entering the blood stream. After in vivo topical application of a 64.5mM alcoholic solution of [(3)H]triclosan to rat skin, 12% radioactivity was recovered in the faeces, 8% in the carcass 1% in the urine, 30% in the stratum corneum and 26% was rinsed from the skin surface at 24 hours after application. Free triclosan and the glucuronide and sulfate conjugates of triclosan were found in urine and faeces. triclosan penetrated rat skin more rapidly and extensively than human skin in vitro. 23% of the dose had penetrated completely through rat skin into the receptor fluid by 24 hours, whereas penetration through human skin was only 6.3% of the dose. Chromatographic analysis of the receptor solutions showed that triclosan was metabolized to the glucuronide, and to a lesser extent to the sulfate, during passage through the skin. triclosan glucuronide appeared rapidly in the receptor fluid whereas triclosan sulfate remained in the skin. Although the major site of metabolism was the liver, conjugation of triclosan in skin was also demonstrated in vitro and in vivo, particularly to the glucuronide conjugate which was more readily removed from the skin. The in vitro system provides a reasonable estimate of dermal absorption in vivo for the rat. Therefore by extrapolation of the comparative in vitro data for human and rat skin it is reasonable to deduce that dermal absorption in human of triclosan applied at the same dose is about one-third of that in the rat in vivo.

Biomechanical performance of latex and non-latex double-glove systems

The purpose of this study was to evaluate ten commercially available latex, powder-free surgical gloves and four commercially available non-latex, powder-free surgical gloves using standardized, reproducible biomechanical parameters that included glove thickness, puncture resistance, and glove donning force. For all gloves tested, with one exception (Neolontrade mark PF), puncture resistance increased for double-gloves as compared to single-gloves. In addition, single-glove thickness was not a reliable determinant of puncture resistance for either latex or non-latex gloves. For the latex gloves, the Ultrafree double and single-gloves exhibited the highest puncture resistance. The glove donning forces for the Biogeltrade mark M and Biogel Sensortrade mark single-gloves were the lowest. In contrast, the Biogel Revealtrade mark and Encoretrade mark Ultra-Thick exhibited the lowest double-glove donning forces. On the basis of these performance tests of latex gloves, the surgeon should consider the Biogel Reveal as well as the Ultrafree gloves for their latex double-glove system. For the non-latex gloves, the Pure Advantage Nitriletrade mark glove had the highest puncture resistance for one layer and two layers of glove material. The thin Pure Advantage Nitrile glove was the most resistant to glove puncture. The Pure Advantage Nitrile glove had low glove donning forces for both single-glove donning configurations and double-glove donning configurations. Consequently, we recommend the Pure Advantage Nitrile glove as the powder-free, non-latex, double-glove system.

Mutations in the reduced-folate carrier affect protein localization and stability

The reduced-folate-carrier (rfc) gene has been shown to be functionally important for reduced-folate transport in mammalian cells. In the present paper we describe the identification of alterations in both alleles of the rfc gene in a mutant Chinese-hamster ovary cell line deficient in methotrexate transport. One allele of the rfc gene contains a point mutation resulting in a Gly(345)-->Arg substitution in the predicted amino acid sequence. In this case, a protein of similar size to the wild-type protein is produced, although it remains as an immature, core-glycosylated, form. The second allele contains a point mutation in the last base of intron 5 that results in the utilization of a cryptic splice site leading to a seven-base deletion in the mRNA. The use of an alternate splice site changes the reading frame to yield a truncated protein with 68 different C-terminal amino acids as compared with the wild-type. Both of these altered gene products were monitored by fusion with green fluorescent protein and found to be non-functional with an increased rate of turnover. The protein with the point mutation is trapped in the endoplasmic reticulum with subsequent degradation, whereas the product of the splice mutation is not membrane-associated and is partially degraded. Thus mutations in both alleles of the rfc gene in this resistant cell line account for the loss of reduced-folate transport. The observations made regarding the degradation of these mutant gene products also provide support for putative checkpoints in the endoplasmic reticulum.

Global epidemic of human T-cell lymphotropic virus type-I (HTLV-I)

Infection with human T-cell lymphotrophic virus-I (HTLV-I) is now a global epidemic, affecting 10 million to 20 million people. This virus has been linked to life-threatening, incurable diseases: adult T-cell leukemia/lymphoma (ATLL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The cumulative lifetime risk of developing these incurable diseases is approximately 5% in asymptomatic patients. For the emergency physician practicing among patients from high-risk groups, HTLV-I and its associated diseases are presenting an increasing challenge. This report describes its transmission, seroprevalence, treatment, and methods of controlling spread of this retrovirus. Coinfection with HTLV-I and HIV has been shown to accelerate the progression of acquired immune deficiency syndrome (AIDS).

Biomechanical performance of powder-free examination gloves

Biomechanical performance studies were undertaken for powder-free, latex and nitrile examination gloves. Using standardized tests, examination glove performance was judged by measuring glove thickness, glove puncture force, glove tape adhesion force, glove donning force, glove stiffness, and immediate unrecovered stretch. Even though the nitrile examination gloves were thinner than the latex examination gloves, they exhibited a greater puncture resistance. In addition, tape adherence to the N-Dex nitrile glove was the lowest. Moreover, measurements of the handling characteristics of the nitrile examination gloves demonstrated that they are an acceptable alternative to latex examination gloves. While these biomechanical studies demonstrate the superiority of the nitrile examination gloves, clinical glove evaluation is still needed to determine their performance in the health care setting.

Integrity of powder-free examination gloves to bacteriophage penetration

The purpose of this study was to compare the resistance to viral penetration of powder-free synthetic examination gloves with powder-free latex examination gloves commonly used in hospitals. Because these gloves had no holes, this study examined viral penetration through a membrane. Using a standard bacteriophage penetration model, no bacteriophage penetration was detected through the membrane for any of the gloves tested. The new powder-free nitrile and polyvinyl chloride synthetic examination gloves provided comparable resistance to viral penetration as did the powder-free latex examination gloves.

Biomechanical performance of examination gloves

The purpose of this study was to compare the biomechanical performance of new powder-free commercially available synthetic examination gloves to that of commercially available powder-free latex examination gloves. The synthetic gloves were significantly thinner than the latex gloves. Despite the decreased thickness, all three nitrile gloves, as well as the polyvinyl chloride glove, exhibited a greater resistance to glove puncture. The glove donning forces varied considerably among all gloves, and wet donning forces were greater than dry donning forces. Under dry conditions, the donning forces for the synthetic gloves were less than or equal to the forces for the latex gloves. Because of their increased puncture resistance and similar donning forces, synthetic gloves are a safe alternative to latex examination gloves.

The role of metabolism in determining susceptibility to parathion toxicity in man

Human liver microsomes (n = 16) activated parathion (O, O, diethyl O-p-nitrophenyl phosphorothioate, 20 and 200 microM) to paraoxon at a rate of 23.3-199.3 and 18.7-310.3 pmol/min per mg protein, respectively. p-Nitrophenol, was also formed, at 321.1-769.2 and 406.2-778.3 pmol/min per mg protein. This represented a 16-fold and 2-fold range in capacity to activate and detoxify parathion, respectively. Parathion was activated with an apparent Km of 9-16 microM (n = 3). The activation of parathion (200 microM) was positively correlated with nifedipine oxidation, indicating the involvement of CYP3A. Correlations were not significant with ethoxyresorufin-O-dealkylation (CYP1A1/2), pentoxyresorufin-O-dealkylation (CYP2B6), p-nitrophenol hydroxylation (CYP2E1), paraoxon hydrolysis (A-esterase) or phenylvalerate hydrolysis (B-esterase). Paraoxon formation from parathion was markedly reduced by CYP3A inhibitors. Experiments with EDTA indicated that A-esterase was not functionally important at low levels of paraoxon. Human P450s 3A4 and 3A5 expressed microsomes were the most efficient at biotransforming parathion to paraoxon, although P450s 1A1, 2B6 and 2C8 also catalysed the reaction. This study has determined wide interindividual variations in capacity to metabolise parathion, mainly by CYP3A, which may influence its manifest toxicity.

The antiphospholipid or Hughes' syndrome: an underdiagnosed cause of thrombosis

The antiphospholipid or Hughes' syndrome is the association between antiphospholipid antibodies, recurrent venous and arterial thromboses and recurrent fetal loss. There are many clinical manifestations arising from this acquired thrombophilia and these are described in the article. The pathogenic mechanism by which the antibodies cause thrombosis is the subject of much debate, and current theories are described. The diagnosis and management of patients with the syndrome are also discussed.

Reactivation of coccidioidomycosis in a fit American visitor

The case history is presented of an American visitor, known to have had primary coccidioidomycosis previously, who became very unwell during a visit to the UK. Despite consideration of reactivation of coccidioidomycosis from the outset, other pathogens were identified while Coccidioides immitis was not initially, leading to a delay in treatment.

Accelerated cutaneous nodulosis during methotrexate therapy in a patient with rheumatoid arthritis

Rheumatoid nodulosis is characterized by multiple small subcutaneous granulomatous nodules typically located on the elbows in approximately 20% of patients with rheumatoid arthritis. Accelerated rheumatoid nodulosis, especially involving the hands and feet, has recently been reported in patients receiving methotrexate therapy for rheumatoid arthritis. We describe a woman with seropositive, erosive rheumatoid arthritis who, on two occasions, developed nonperiarticular subcutaneous nodules and new heart murmurs during methotrexate therapy, while her arthritis remained under good control. The nodules resolved after methotrexate was discontinued and recurred after methotrexate was reintroduced. They again resolved after methotrexate was stopped and colchicine was added. Her DNA oligotyping was positive for HLA-DRB1*0401, a genetic risk factor associated with accelerated rheumatoid nodulosis. Cutaneous biopsy specimens revealed palisading granulomas and giant cells consistent with rheumatoid nodulosis.

A comparison of the electrophysiological effects of two organophosphates, mipafox and ecothiopate, on mouse limb muscles

Adult male albino mice were given single subcutaneous injections of either mipafox (110 mumol/kg) or ecothiopate (0.5 mumol/kg), two organophosphorus compounds (OPs). Acetylcholinesterase activity was measured in the soleus (slow-twitch) and extensor digitorum longus (EDL; fast-twitch) muscles. At 7 and 28 days after dosing, in vitro electrophysiological measurements were carried out in the soleus and EDL. Action potentials and end-plate potentials were evoked at 30 Hz and recorded intracellularly from single muscle fibers. The amplitudes, time course, and latencies of these potentials were measured and the variability (jitter) of latencies was calculated. Recordings after mipafox were also made with 3-Hz stimulation. Acetylcholinesterase activity was inhibited by mipafox (65% in the soleus; 76% in the EDL) and ecothiopate (59% in the soleus; 42% in the EDL). Mipafox and ecothiopate both increased postjunctional (muscle action potential) jitter in the soleus and EDL at 7 days after dosing. Organophosphates caused an increase in end-plate potential amplitudes in the soleus. Mipafox caused an increase in prejunctional (end-plate potential) jitter at 28 days after dosing in both muscles. A single dose of ecothiopate also caused an increase in prejunctional jitter at 28 days in the soleus. The OP-induced increase in jitter was different at different frequencies of stimulation. The results show that there are electrophysiological changes in both muscles after administration of organophosphorus compounds. The slow-twitch soleus appears more sensitive to prejunctional changes caused by OPs than the fast-twitch EDL.

Structural organization of the human reduced folate carrier gene: evidence for 5' heterogeneity in lymphoblast mRNA

The reduced folate carrier (rfc1) gene encodes a protein that is involved in the intracellular accumulation of folates. Point mutations in this gene and alterations resulting in the down regulation of its message are major factors involved in the resistance to antifolate chemotherapeutic compounds. As a framework for understanding the significance of such changes in relation to gene expression and function, in this report we describe the organization of the rfc gene from human lymphoblasts. The gene contains 5 exons (2 to 6) coding for protein. At least four 5' exons, used in a mutually exclusive manner in the production of the rfc message from lymphoblast cells, are spliced to exon 2, which contains the translational start site. "Semi-quantitative" PCR indicates that exon 1 is preferentially used. The major transcriptional start site has been mapped by RACE and RNase protection to a region 109 to 135 base pairs 5' to the start of exon 1. The 5' region of the gene has no TATA box-like sequence but contains several consensus binding sites for transcriptional factors such as SP-1, MZF1, CREB, AP-1, ETS, GATA-1 and GATA-2. The overall organization of the human gene is similar to that of the hamster and mouse genes.

Prevalence of the diffuse infiltrative lymphocytosis syndrome among human immunodeficiency virus type 1-positive outpatients

OBJECTIVE

To ascertain the prevalence of the diffuse infiltrative lymphocytosis syndrome (DILS) in human immunodeficiency virus type 1 (HIV-1)-positive outpatients.

METHODS

The presence of sicca symptoms and visible salivary gland enlargement was determined by interview and physical examination, and the clinical stage was determined by chart review, in 523 HIV-positive patients. The diagnosis of DILS was established in those with parotid gland enlargement by minor salivary gland biopsy or radionuclide scintigraphy.

RESULTS

Definite DILS was found in 15 (3%) of the 523 patients, and possible DILS in 18 (3.4%). The prevalence of definite DILS was significantly higher in African Americans (4.5%). Self-reported facial swelling and xerophthalmia that was not explained by the effects of medication were found more frequently in those with DILS than in the non-DILS patients. Patients with DILS had higher CD8 counts (mean +/- SD 1,456 +/- 813/mm3) compared with those without DILS (934 +/- 624/mm3; P < 1 x 10(-6)), and were less advanced in their HIV clinical stage (Centers for Disease Control and Prevention stages A or B in 76% compared with 60% of the non-DILS group; P = 0.01).

CONCLUSION

DILS is an important problem in HIV-infected outpatients and tends to occur in patients whose clinical disease is at a less advanced stage. Patients with parotid gland enlargement accompanied by sicca symptoms should be screened for HIV infection.

Effect of Tri-O-cresyl phosphate (TOCP) on proteolytic enzyme activities in mouse liver in vivo

To develop a clearer understanding of the biochemical mechanisms of toxicity in higher animals, we determined the effect of four sublethal dosages (0.25 to 1.0 g/Kg) of organophosphate (OP), and of tri-ortho-cresyl phosphate (TOCP) on the activities of a representative range of cytoplasmic and lysosomal proteolytic enzymes in mouse liver in vivo. Administration of the lowest sublethal dosage of TOCP (0.25g/1Kg, 24 hours) resulted in significant inhibition (10 to 30% of control activity) of the cytoplasmic proteases tripeptidyl aminopeptidase and proline endopeptidase only. An increasing dosage of TOCP (1g/Kg for 7 days) resulted in significant inhibition (10 to 50% of control activity) of the cytoplasmic proteases alanyl aminopeptidase, leucyl aminopeptidase, tripeptidyl aminopeptidase, and proline endopeptidase, as well as the lysosomal proteases dipeptidyl aminopeptidase I and cathepsins B, D, and L. The activities of the cytoplasmic proteases arginyl aminopeptidase and dipeptidyl aminopeptidase IV, and of lysosomal proteases dipeptidyl aminopeptidase II and cathepsin H were not significantly altered following TOCP administration at this higher dosage. All of the above proteases are involved in the general process of intracellular protein turnover (common to all tissues), and may also have more specialized functions such as the processing of physiologically active hormonal peptides, and the processing of antigenic proteins in the immune response. Data obtained in the present study suggest that inhibition of the above enzymes by OP such as TOCP may represent a previously unrecognized toxicity hazard induced by the latter compound in higher animals.

The percutaneous absorption and skin distribution of lindane in man. II. In vitro studies

1. The absorption of lindane through human skin was assessed in vitro using static diffusion cells with 50% aqueous ethanol as the receptor fluid. Four formulations of lindane were applied, three of which were commercial preparations. The dermal distribution of lindane within the skin was also examined, focusing particularly on any association of lindane to the stratum corneum. The results were then compared with a parellel in vivo study. 2. Two of the formulations contained white spirit as the predominant solvent, and lindane absorption was greatest from these preparations in terms of the percentage of the applied dose (15-25% by 24 h). Absorption was less from an aqueous spray dilution (3% by 24 h), with absorption from acetone being the least (< 1% by 24 h). Similar amounts of lindane penetrated by 24 h for the acetone and white spirit-based applications (approx. 8 micrograms). This supported the in vivo observation that similar plasma lindane levels were recorded following exposure to the acetone solution and the white spirit-based formulation A, although the lindane concentration in acetone was 40-fold higher. 3. For the acetone and water-based preparations, a soap/water swab of the skin surface at 6 h contained the majority of the applied dose (around 75%). Substantial amounts of lindane were recovered in tape-strippings taken at 6 h (representative of stratum corneum content) which were significantly greater than lindane in the remainder of the skin, for the acetone solution and formulation A. This provided a strong indication that lindane had accumulated in the stratum corneum, a property that has been linked with other lipophilic chemicals.

The percutaneous absorption and skin distribution of lindane in man. I. In vivo studies

1. The absorption and distribution of lindane through skin was examined using human volunteers. Two different preparations were employed, one with acetone as the vehicle and the other, a commercial product, consisting primarily of white spirit as the solvent base. 2. The mean peak plasma concentrations of lindane following exposure to the acetone and white-spirit based applications were 0.91 and 0.47 ng/ml, respectively. The similarity between these levels did not reflect the 40-fold higher dose of lindane in the acetone vehicle. White spirit enhanced the penetration of lindane with respect to the acetone vehicle, highlighting the influence of vehicle upon percutaneous absorption. Low levels of trichlorophenol glucuronide metabolites, but no lindane, were detected in the urine. 3. The exposure site was washed at 6 h to mimic a decontamination procedure at the end of a working day. The proportion of the applied dose unabsorbed by 6 h was 80% and 10% for the acetone and the white spirit-based formulation, respectively. Small areas of the exposed site were tape stripped at 6 and 24 h to assess any lindane that may be associated with the stratum corneum. High levels were observed in the stratum corneum at 6 h exposure (up to 30% of the applied dose for the white spirit based formulation). However, this level had decreased by 24 h (by at least 90% of the amount found at 6 h). A gauze or gauze/shirt combination covering the application site between 6 and 24 h did account for some of this loss of lindane from the stratum corneum attributed to friction and removal of exfoliated cells. The unaccounted proportion was presumed to have been absorbed through the skin into the systemic circulation. This demonstrates the absorption of chemicals can occur from a depot in the stratum corneum even following a wash procedure.

Percutaneous penetration of 2-phenoxyethanol through rat and human skin

2-Phenoxyethanol applied in methanol was absorbed (64 +/- 4.4% at 24 hr) through unoccluded rat skin in vitro in the static diffusion cell with ethanol/water as receptor fluid. By comparison (43 +/- 3.7% in 24 hr) was absorbed in the flow-through diffusion system with tissue culture medium as receptor fluid. 2-Phenoxyethanol applied in methanol was absorbed (59.3 +/- 7.0% at 6 hr) through unoccluded human skin in vitro in the flow-through diffusion cell with tissue culture medium. With both unoccluded cells, 2-phenoxyethanol was lost by evaporation but occlusion of the static cell reduced evaporation and increased total absorption to 98.8 +/- 7.0%. Skin, post mitochondrial fraction, metabolized phenoxyethanol to phenoxyacetic acid at 5% of the rate for liver. Metabolism was inhibited by 1 mM pyrazole, suggesting involvement of alcohol dehydrogenase. However, first-pass metabolism of phenoxyethanol to phenoxyacetic acid was not detected during percutaneous penetration through viable rat skin in the flow-through system. First-pass metabolism in the skin does not therefore have an influence on systemic availability of dermally absorbed phenoxyethanol. These measures of phenoxyethanol absorption through rat and human skin in vitro agree well with those obtained previously in vivo.

Role of nitric oxide in the dilator actions of capsaicin-sensitive nerves in the rabbit coronary circulation

Perivascular sensory nerves release calcitonin gene-related peptide (CGRP) and substance P, the dilator actions of which can be regulated by nitric oxide (NO). This study investigated the role of NO in the vasodilation caused by sensory nerve stimulation, by capsaicin, or exogenous CGRP and substance P in the isolated perfused coronary circulation of the rabbit. Coronary perfusion pressure (CPP) was raised in order to observe vasodilator responses, using the thromboxane mimetic, U46619. Capsaicin (3 x 10(-6) moles), alpha CGRP (3 x 10(-11) moles) and substance P (3 x 10(-12) moles) caused comparable reductions in CCP. At these concentrations, responses to capsaicin and CGRP were inhibited by the antagonist CGRP(8-37) but unaffected by the neurokinin-1 receptor antagonist, CP 96,345. The nitric oxide synthase inhibitor, NG nitro L-arginine methyl ester inhibited the effects of substance P and capsaicin but not CGRP. These results suggest that CGRP release following capsaicin-induced sensory nerve activation is modulated by NO.

Effect of pirimiphos-methyl on proteolytic enzyme activities in rat heart, kidney, brain and liver tissues in vivo

To elucidate whether pesticide toxicity in higher animals involves pesticide-induced dysfunction of the intracellular protein catabolic process, we have determined the effect in vivo of the organophosphate insecticide pirimiphos-methyl on the activities of representative protein catabolising cytoplasmic and lysosomal proteases (responsible for the various stages of the protein degradation cascade and essential for normal cell functioning) in heart, kidney, brain and liver target tissues in the rat. In liver tissue (the major site of pesticide metabolism), the activities of all of the cytoplasmic proteases investigated (alanyl-, arginyl-, leucyl aminopeptidases, dipeptidyl aminopeptidase IV, tripeptidyl aminopeptidase, proline endopeptidase) were significantly inhibited (by 20-40% of control activity) following administration of 10 mg pirimiphos-methyl/kg bodyweight, whereas of the lysosomal proteases investigated, only the activities of dipeptidyl aminopeptidase I and cathepsin D were significantly reduced (by 15-20% of control activity). In contrast, there was no insecticide-induced inhibition of protease activities in heart, kidney or brain tissues; some lysosomal enzymes (dipeptidyl aminopeptidase I, cathepsins L and D) showed significantly increased activities in these tissues (the reason for which remains to be determined). We conclude that the effect of pirimiphos-methyl on proteolytic enzyme activities differs in different target tissues, and that pirimiphos-methyl induced inhibition of proteases in liver tissue may represent a previously unrecognised toxicity hazard in higher animals.

Metabolism of n-hexane by rat liver and extrahepatic tissues and the effect of cytochrome P-450 inducers

1. The in vitro metabolism of n-hexane was studied in rat liver, lung, brain and skeletal muscle microsomes and in microsomes prepared from cell lines expressing human cytochrome P-450 2E1 or 2B6. The hydroxylated metabolites of n-hexane were quantified by gas chromatography-mass spectometry. 2. Rat liver and extensor digitorum longus (EDL, fast-twitch skeletal muscle) microsomes and the CYP 2B6 microsomes produced the pre-neurotoxic metabolite of n-hexane, 2-hexanol as a major metabolite in contrast to the other rat tissues examined. 3. Inhibition of 2- and 3-hexanol production from n-hexane by rat lung microsomes using metyrapone, an inhibitor of cytochrome P-450 2B1 activity, resulted in almost complete inhibition of lung microsomal activity. 4. Production of all three hexanols was significantly increased with phenobarbital-induced rat liver microsomes, with a 10-fold increase in 2- and 3-hexanol production. A slight increase in 2-hexanol production with phenobarbital-induced rat EDL and brain microsomes was observed. No increase in n-hexane metabolism was noted following induction with beta-naphthoflavone or with ethanol.

An investigation into the role of rat skeletal muscle as a site for xenobiotic metabolism using microsomes and isolated cells

1. The role of skeletal muscle microsomes as a site of extrahepatic xenobiotic metabolism using n-hexane as a model substrate was investigated. The observed cytochrome P450-dependent metabolism was compared with that found with liver, and brain microsomal fractions. 2. Rat skeletal muscle microsomes metabolised n-hexane to 1-, 2- and 3-hexanol at rates 40-300 times lower than observed with rat liver microsomes. 3. Fast-twitch extensor digitorum longus muscle (EDL) microsomes had twice as much n-hexane hydroxylase activity as the slow-twitch soleus and furthermore the EDL microsomes produced 2-hexanol, a bioactivation product of n-hexane, as a major metabolite. 4. Metabolism of hexane to 1-, 2- and 3-hexanol and 2-hexanon was demonstrated in cultured rat myoblasts. 5. Ethoxyresorufin and pentoxyresorufin O-dealkylation were not detected in either muscle microsomes or myoblasts although immunocytochemical localisation studies were suggestive of the presence of cytochrome P-450. 6. In conclusion, rat skeletal muscle has a low level of xenobiotic metabolism activity. The relevance to neuromuscular toxicity of n-hexane is discussed.

Effects of multiple doses of organophosphates on evoked potentials in mouse diaphragm

1. Male albino mice were injected s.c. with an organophosphate (mipafox, ecothiopate or paraoxon). Treatments were either a single injection or multiple daily injections with lower doses for 5 or 8 days. At 3 h after injection the activity of brain and diaphragm acetylcholinesterase and of brain neuropathy target esterase (NTE) was measured. Also measured in the diaphragm at 3 h post dose was the duration of spontaneous miniature endplate potentials (eMEPPs), recorded extracellularly. 2. At 7 and 28 days after dosing action potentials and evoked endplate potentials, produced by stimulating the phrenic nerve at 30 Hz, were recorded in diaphragm muscle. The amplitudes, time-course and latencies of these potentials were measured and the variability of latencies (jitter) was calculated. 3. Single doses of mipafox (20 mg/kg), ecothiopate (0.192 mg/kg) or paraoxon (0.415 mg/kg) in the mouse produced ca. 70% inhibition of diaphragm acetylcholinesterase at 3 h after dosing. All three OPs produced a prolongation of the half-decay times of eMEPPs. 4. All three OPs in the above single doses produced increased muscle action potential (postjunctional) jitter but only mipafox produced an increase in endplate potential (prejunctional) jitter. Mipafox in a slightly reduced single dose (17.5 mg/kg) had no effect on prejunctional or postjunctional jitter. 5. Multiple dosing with mipafox (8 mg/kg daily for 5 days) increased both postjunctional and prejunctional jitter at both 7 and 28 days after the end of dosing. After multiple dosing with mipafox (5 mg/kg daily for 5 days) postjunctional (but not prejunctional) jitter was increased. Multiple doses of paraoxon (0.166 mg/kg daily for 5 days) or ecothiopate (0.76 mg/kg daily for 5 days) increased prejunctional and postjunctional jitter. 6. Depending on the dosing regime, all three OPs tested were capable of increasing both prejunctional and postjunctional jitter. Neither ecothiopate nor paraoxon inhibited NTE, so this prejunctional effect is not likely to be related to 'classical' OP-induced delayed neuropathy. The prejunctional effects may be related to long-term inhibition of acetylcholinesterase and the triggering mechanism for increase in prejunctional jitter may involve a relationship between the inhibition of acetylcholinesterase and the time for which it is inhibited. The differences between the time-courses of increases in prejunctional and postjunctional jitter and the differential effects of the different multiple dosing regimes indicate that it is likely that the triggering relationship between enzyme inhibition and time is different for prejunctional and postjunctional effects.

The effects of multiple low doses of organophosphates on target enzymes in brain and diaphragm in the mouse

1. Multiple low doses of the direct acting organophosphates, ecothiopate, paraoxon and mipafox produced persistent and additive inhibition of diaphragm acetylcholinesterase. Paraoxon and mipafox had similar effects on brain acetylcholinesterase. There was greater recovery from inhibition between doses for paraoxon and ecothiopate than for mipafox. 2. Ecothiopate did not inhibit brain acetylcholinesterase but there was a small increase in activity. 3. Mipafox also had a cumulative inhibitory effect on brain neuropathy target esterase. 4. These results have particular implication for the use of multiple low doses of organophosphates occupationally by man.

Exposure factors that contribute to variability in toxic responses in man

The route of exposure is an important determinant of the internal dose of a chemical in man and the expression of toxicity. Routes of exposure are inhalation via the lung and dermal penetration, and the degree of absorption and first pass metabolism vary between chemicals. Inter-individual differences in metabolism of both genetic and environmental cause contribute to variability in metabolic fate and toxic response.

Structural organization of the reduced folate carrier gene in Chinese hamster ovary cells

The reduced folate carrier gene (rfc) encodes a putative protein that is involved in the intracellular accumulation of folates. In this report, we describe the organization of the rfc gene from Chinese hamster ovary cells. The hamster rfc gene contains 7 exons and 6 introns, which span 15.3 kilobases. It codes for two alternatively spliced messenger RNAs, one that contains all 7 exons and one that lacks exon 2 but contains the remaining 6 exons. The transcriptional start of the gene has been mapped to six sites approximately 200 base pairs upstream of the putative ATG initiation codon. The promoter region has no TATA box-like sequence but contains a consensus Sp1 binding site. This is the first report of the genomic structure of the reduced folate carrier gene from any species.

The effect of sulphur mustard on glutathione levels in rat lung slices and the influence of treatment with arylthiols and cysteine esters

1. Sulphur mustard reacts directly with benzenethiols and cysteine esters in aqueous medium. 2. Benzenethiols diffuse into lung slices in short term culture. 3. Treatment of lung slices in short term culture with benzenethiols does not protect cellular glutathione from conjugation with sulphur mustard. 4. Following uptake of cysteine ester into lung slices cysteine is elevated but this does not protect cellular glutathione from sulphur mustard.