Long-term immunity after HBV vaccine: shall we consider a change? A 20-year-follow-up study

Introduction

Although vaccines against HBV have been available since the 1980s, the long-term immunity is still debated. When assessing immune persistence, a number of clearly defined variables must be taken into account. Often the expression ‘infant vaccination’ means the administration within the first year of life at any age, but a difference of a few months may imply a different antibody persistence over the years. This study assessed the anti-HBs titre 20 years after the primary vaccination course and estimated the effect of age at 1st dose and time interval between doses on long-term protection.

Methods

Data on age, sex and date of administration were collected. Inclusion criteria: born to negative mother, 3-dose schedule, no previous HBV infection, age at enrolment 18-24 years; age at 1st dose 2-12 months. Titres ≥10IU/l were considered protective. A logistic regression was performed, adjusting for sex, follow-up time and date of 1st dose and analysis.

Results

We included 5,485 participants (64% female). The mean anti-HBsAg increased from 46, 52, 85 to 193IU/l when the 1st dose was administered in the I, II, III or IV trimester of life, respectively. Similarly, the proportion of individuals with titre <10IU/l decreased from 51 to 18% between the two extreme quarters. The risk of a titre <10IU/l decreased with age at the 1st dose (AOR: 0.84; 95%CI: 0.78-0.91 per one-month increase) and time between the 2nd and 3rd doses (AOR: 0.89; 95%CI:0.85-0.94).

Conclusions

The mere presence of a titre <10IU/l does not equate lack of protection. However, antibody levels are very different depending on the actual age of vaccination. One-month delay within the first year is associated with a -18% chance of a titre <10IU/l 20 years later. Although this information needs to be combined with local epidemiology and surveillance to obtain an informed risk-benefit balance, the implications from a public health and economic perspective may be diverse and worth considering.

Key messages

• Still within the first year of life, a delay in the administration of the 1st dose of HBV vaccine and a longer time between the 2nd and 3rd dose imply a higher antibody persistence even 20 years later.

• Considering the local circulation of HBV and surveillance, this result could be taken into account to obtain an informed risk-benefit balance.

Transparency and sustainability in global commodity supply chains

Over the last few decades rapid advances in processes to collect, monitor, disclose, and disseminate information have contributed towards the development of entirely new modes of sustainability governance for global commodity supply chains. However, there has been very little critical appraisal of the contribution made by different transparency initiatives to sustainability and the ways in which they can (and cannot) influence new governance arrangements. Here we seek to strengthen the theoretical underpinning of research and action on supply chain transparency by addressing four questions: (1) What is meant by supply chain transparency? (2) What is the relevance of supply chain transparency to supply chain sustainability governance? (3) What is the current status of supply chain transparency, and what are the strengths and weaknesses of existing initiatives? and (4) What propositions can be advanced for how transparency can have a positive transformative effect on the governance interventions that seek to strengthen sustainability outcomes? We use examples from agricultural supply chains and the zero-deforestation agenda as a focus of our analysis but draw insights that are relevant to the transparency and sustainability of supply chains in general. We propose a typology to distinguish among types of supply chain information that are needed to support improvements in sustainability governance, and illustrate a number of major shortfalls and systematic biases in existing information systems. We also propose a set of ten propositions that, taken together, serve to expose some of the potential pitfalls and undesirable outcomes that may result from (inevitably) limited or poorly designed transparency systems, whilst offering guidance on some of the ways in which greater transparency can make a more effective, lasting and positive contribution to sustainability.

Synthesis, chemical characterization and cancer cell growth-inhibitory activities of Cu(ii) and Ru(iii) aliphatic and aromatic dithiocarbamato complexes

The effects mediated by different cyclic dithiocarbamic ligands on three classes of antiproliferative coordination compounds were studied.

Method of capture and population structure of Aegla georginae Santos and Jara, 2013 (Decapoda: Anomura: Aeglidae) in a tributary of the Ibicuí River in southern Brazil

In the current study, we investigated population aspects of Aegla georginae in the Ibicuí River Basin by considering different capture methods and the implication of these data in the analysis of population dynamics. We sampled 1774 individuals: 1259 males (21 and 97 juveniles and 1029 and 113 adults in trap and handnet, respectively), 512 females (05 and 140 juveniles, 184 and 64 adults, and 81 and 38 ovigerous in trap and handnet, respectively) and 03 unsexed individuals (02 and 01 in trap and handnet, respectively). The frequency distribution in size classes shows a bimodal model for both sexes. The carapace length (CL) in males and females varied from 3.11 to 26.00 and 3.73 to 22.36 mm, respectively. Males presented significantly larger sizes than females. The relative abundance between males and females was significantly different from 1:1 with more males than females in most sampling periods (p < 0.05) when considering the grouped data (handnet + trap) and trap captures, but followed the expected ratio in most months when considering individuals sampled only with handnet (p > 0.05). Juveniles were recorded in all seasons, and reproduction occurs throughout the year. The population structure is similar to the model known for aeglids, and the capture methods affected the analysis of A. georginae, where the grouped data and trap captures presented greater abundance of individuals than handnet and males predominate in the larger size classes, and females in the intermediary size classes. Therefore, an integrated view of the capture methods is the best model for studying the population dynamics of aeglids.

Kidney and liver biomarkers in female dry-cleaning workers exposed to perchloroethylene

Blood and urine perchloroethylene and urine trichloroacetic acid, as markers of exposure, and serum AST, ALT, GGT and creatinine, urine total solutes and proteins, angiotensin converting enzyme, N-acetyl-ß-D-glucosaminidase and glutamine synthetase, as markers of effect, were measured in 40 dry-cleaning and 45 ironing-shop female workers. Average perchloroethylene air level in the dry-cleaning shops was 59.7 mg m(-3), i.e. three-fold lower than the current A.C.G.I.H. TLV-TWA (170 mg (m-3)). No statistically significant difference in the mean values of any of the effect markers was observed between the two groups, except for AST which was significantly higher in drycleaners. In addition, a statistically significant correlation was observed in dry-cleaners between environmental perchloroethylene and total urinary solutes (r = 0.308, p &lt; 0.05) or urine glutamine synthetase (r= 0.469, p &lt; 0 .01), between glutamine synthetase and blood perchloroethylene in post-shift (r= 0.406, p &lt; 0.01) or urinary perchloroethylene in post(r= 0.571, p &lt; 0.001) or pre-shift (r= 0.586, p &lt; 0.001), and between urinary perchloroethylene in pre-shift and GGT (r= 0.407, p &lt; 0.05). Interestingly, some statistically significant correlations between exposure and effect indices were found in ironing-shop workers alone, as in all subjects. Finally, transaminases, GGT and total urinary proteins were influenced by age and alcohol consumption which were significantly higher in dry-cleaners, thus providing an explanation for some of the correlations observed. In conclusion, our results show a dose-related increase of glutamine synthetase activity,a marker of damage of the pars recta of the kidney proximal tubule, in the urine of female subjects exposed to perchloroethylene concentrations in the work environment lower than current A.C.G.I.H. TLV-TWA.

Modeling the Praia dos Ingleses submarine outfall, Florianópolis, Santa Catarina, Brazil

An outfall 1,800 m long was initially proposed by CASAN (Water and Sanitation Company of Santa Catarina) to dispose of treated domestic residual water effluent from Praia dos Ingleses beach. The final plan average flow, estimated for the summer season is 0.1543 m³/s. The characteristics on the near field of the diffuser were calculated using the NRFIELD model supplied by a series of current profiles and density, gathered at the diffuser location between March and April, 2007. Reliable information of raw sewage fecal coliform concentration and nutrients has been supplied by CASAN, based on continuous monitoring of sewage in its treatment plants. The diffuser was designed in such a way that it maximizes the initial dilution allowing the nutrients concentration to comply with legislation limits. However, results showed that the treatment plant should be designed to mainly reduce total phosphorus. A hydrodynamic model was implemented to generate current fields for the far field modeling. Information gathered in the field on variation in water level, wind, and current velocity and direction was used for boundary and/or initial conditions. Then, a Lagrangian advective-diffusive model was used to evaluate the extent of the plumes. The results of far field modeling showed a need to increase the outfall length. A new location 3,300 m from the beach has been proposed.

Biological monitoring of exposure to perchloroethylene in dry cleaning workers

BACKGROUND

Perchloroethylene (PCE) is the most widely used solvent in dry cleaning.

OBJECTIVES

The aim was to evaluate PCE pollution and to identify the most reliable biological indicators for the assessment of workers' exposure.

METHODS

The study was performed in 40 dry cleaning shops covering a total of 71 subjects. Environmental monitoring was carried out with personal diffusive samplers (Radiello) for the entire work shift; biological monitoring was performed by measuring PCE in urine and blood and trichloroacetic acid (TCA) in urine on Thursday evening at end-of shift and on Friday morning pre-shift.

RESULTS

The mean concentration of PCE in air was 52.32 mg/m3, about 30% of the TLV-TWA and the mean value of the PCE inpre-shift blood samples was 0.304 mg/l, slightly more than 50% of the BEI. In dry cleaning shops employing less than 3 persons PCE in air exceeded the TLV-TWA in 7.8% of cases; the size of the shops was inversely related to pollution. Statistically significant correlations were found between PCE exposure and PCE in blood end-of-shift (r = 0.67) and pre-shift (r = 0.70), and PCE in urine end-of-shift (r = 0.68); no correlation was found between exposure and PCE in urine pre-shift and urinary TCA.

CONCLUSIONS

Dry cleaning shops still register conditions of exposure and pollution by PCE, although to a lesser extent than in the past. The most reliable indicators for biological monitoring are CE in end-of-shift urine and PCE in blood both at end-of-shift and pre-shift at the end of the workweek.

[Release of metals from metal-on-metal hip prostheses]

The present study examined blood and urinary concentrations of Cr and Co in 30 patients with metal-on-metal hip prostheses without signs of wear and 6 patients with prosthetic bearing and clear signs of wear and metallosis. The determination in biological fluids showed in patients with not signs of wear the geometric mean concentration of metals only modestly increased (CoS 0.5 microg/l, CoU 5.7 microg/l, CrS 0.8 microg/l, CrU 3.4 microg/l) compared to the reference values, while the wear caused a significant increase in the concentration of both Co (CoS 94.6 microg/l, CoU 334.5 microg/l) and Cr (CrS 57.7 microg/l, CrU 89.4 microg/I). As the results, the not functioning implants are a risks to the patients and are associated with high levels of metals in biological fluids. Currently, the patients with metallosis had not signs and symptoms associated with metal toxicity, but high concentrations could to cause kidney, peripheral nervous system, heart, and thyroid damage.

[Epidemiology of reproductive tract infections in a symptomatic population of North-East of Italy]

AIM

Reproductive tract infections (RTIs) are one of the main causes of morbidity in the world and sexually transmitted infections (STIs) can give rise to severe sequels (inflammatory pelvic disease, etc.). The epidemiology of these infections is changeable and depends on geographical and economical factors, migratory flows and social and sexual habits. This variability, along with the lack of sufficient data in literature, is a serious problem in the development of screening, prevention and therapy strategies centered on local needs. The aim of our study was to evaluate the epidemiology of reproductive tract infections in a symptomatic population of the Nord-East of Italy.

METHODS

In the period January-June 2006, we investigated 207 subjects at the Microbiology and Virology Service of Padua's Hospital, 18-65 years old, males and women, Italian and foreigners. All had symptoms or personal history pointing to a possible reproductive tract infection. For female we collected vaginal and cervical swabs, and for male urethral swabs, for microscopy, the culture for Neisseria gonorrhoeae, Trichomonas vaginalis, Mycoplasma spp., other bacteria and yeasts, and for molecular assay for Chlamydia trachomatis.

RESULTS

Among our population, the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis were respectively 6.28%, 1.93% and 3.86%. STIs were more frequent in males, among foreigners, and in patients aged 18-30 years.

CONCLUSION

From the results obtained, ideas have emerged in order to arrange a qualitative and quantitative optimization of the diagnosis of RTIs, implementing diagnostic paths based on the different typologies of patients and on the local epidemiology.

[Prevalence of virus hepatitis B markers among medical students]

Healthcare workers are a category of subjects at risk of infections higher than general population, though the introduction of vaccination against hepatitis B generally reduced this risk. In the present research, 2137 students of graduate course for health professions were subdivide in two age classes: 25 years old or younger and older than 25 years old according to the vaccination strategy defined by the law 165/91. A high number of students (82.3%) appeared immune against hepatitis B virus, whereas 16.7% were negative. About 30% of negative subjects declared vaccination. Females and subjects 25 years old or younger showed a significantly higher prevalence of anti-HBsAg antibodies (p < 0.001) than males and older subjects respectively. The obtained results show the need to evaluate the immunity status of the healthcare workers in training with the aim to reduce the number of susceptible subjects.

[Biologic risk due to accident in academic personnel]

Needlestick injuries since 2004 to 2006 were evaluated in University healthcare workers that reported an accident by point, sharp or mucosal contamination. During this period, 497 accidents with instruments contamined with biological fluids were reported. The injuries were most frequent between 9 a.m. and 1 p.m. (233 accidents). There is no difference during the week (excluding Saturday and Sunday), whereas February, May, June, and July were the months at risk. The most of accidents were during the first four hours of the job. They were identified 423 known sources and compliance with follow-up was evaluated. Only 26.3% of subjects injured with known hepatitis B source, 32.3% with known HIV source, and 40% with known HCV source completed follow-up. Fortunately, no seroconversion was observed. The lack of compliance with the follow-up, also if the source is known, needs to stimulate healthcare workers to subject to the protocols and to follow the standard procedure to prevent the needlestick injuries.

[Prevalence of hepatitis virus A, B, and C markers according to the geographic origin of medical students]

Antibodies against viral hepatitis A, B and C were evaluated in 221 students of graduate courses of the Medical School of Padua University born in countries different from Italy. Data were compared with those measured in 362 students born in Veneto Region and 87 students born in Centre-Southern Italy. The results showed a high, significant prevalence of positive antibodies against hepatitis A in students from Africa (94.7%), Asia (60.9%), Centre-Southern America (60.9%) and East Europe (52.7%); in Italy, the prevalence was significant in student from Centre-Southern Italy (19.5%). A high prevalence of hepatitis B antibodies was observed in 33.3% of Africa students (two subjects HBsAg positive), in 22.6% of students from East Europe (five subjects HBsAg positive) and in 12.5% of Asian and Centre-Southern American students (one HBeAg positive). Finally, infection with hepatitis C is sporadic and without a significant geographic distribution (three subjects only).

Rheological characterization of polysaccharide-surfactant matrices for cosmetic O/W emulsions

Rheometrical techniques can be profitably used for polysaccharide matrices in order to evaluate their suitability for the preparation of stable cosmetic O/W emulsions. In particular, the rheological properties of aqueous scleroglucan systems were investigated under continuous and oscillatory shear conditions in a polymer concentration range (0.2-1.2% w/w) embracing the sol/gel transition. The effects due to the addition of two different surfactants (up to 10% w/w) were examined at constant polymer concentration (0.4% w/w). The selected additives are a nonionic polymeric siliconic surfactant (dimethicone copolyol) and a cationic surfactant (tetradecyltrimethylammonium bromide), respectively. Polysaccharide-surfactant interactions leading to complex formation were detected also through rheology. The combined action of both nonionic and cationic surfactants in the polymer solution was examined at two different surfactant concentration levels (5 and 10% w/w), demonstrating the beneficial effects produced on the mechanical properties of the polymer matrix by the coexistence of both surfactants. Such beneficial effects are confirmed by the stability and rheology shown by the emulsions prepared. In this way, the results point out the good agreement between the rheology of the continuous phase and the final characteristics of the emulsion obtained.

[Educational and training issues in occupational first aid: the requisites for the teachers of the workers responsible for first aid]

BACKGROUND

The inter-ministerial decree (D.I.) 388/03 (the Italian law on first aid in the workplace) attaches particular importance to the organization of first aid and to the content of the teaching and training of designated workers, specifying teaching objectives, programme and duration of courses. However it provides less details on the requirements and qualifications of the teachers and trainers.

OBJECTIVES

To discuss this topic in the light of the guidelines contained in the literature and the existing legislation.

METHODS

We used the specific references of literature and legislation concerning first aid training of designated workers.

RESULTS

The objectives and the content of the training courses call for a high level of professional competence and approach. Therefore, training of designated workers should be planned and carried out in accordance with the training standards used for the teaching and training of the so-called "lay rescuers".

CONCLUSIONS

The need to achieve high training standards for workers responsible for first aid at the workplace is to a large extent justified by the difficulty of the role of employees. This need follows the current tendency in regulations to guarantee adequate and up-dated training also for other agents operating within the system of workplace prevention. In this context the occupational physician plays a significant role in the training programmes for designated workers.

Pt(II) and Pd(II) derivatives of ter-butylsarcosinedithiocarbamate. Synthesis, chemical and biological characterization and in vitro nephrotoxicity

This work reports on the synthesis, characterization and biological activity of new coordination compounds of the type [M(TSDTM)X(2)] (M=Pt(II), Pd(II); X=Cl, Br; TSDTM=ter-butylsarcosine(S-methyl)dithiocarbamate) and [Pd(TSDT)X](n) (TSDT=ter-butylsarcosinedithiocarbamate) in order to study their behavior as potential antitumor agents. All the synthesized compounds were characterized by means of elemental analysis, FT-IR, (1)H and (13)C-NMR spectroscopy and thermogravimetric analysis, suggesting a chelate S,S' structure of the TSDTM/TSDT ligand in a square-planar geometry. Finally, the synthesized complexes have been tested for in vitro cytotoxic activity against human leukemic HL60 and adenocarcinoma HeLa cells; the most active compound [Pt(TSDTM)Br(2)], characterized by IC(50) values very similar to those of the reference compound (cisplatin), was also tested for in vitro nephrotoxicity showing a very low renal cytotoxicity as compared to cisplatin itself.

Synthesis of a new platinum(II) complex: anticancer activity and nephrotoxicity in vitro

New mixed dithiocarbamate-amino Pt(II) complex ([Pt(ESDT)(Py)Cl]) has been recently synthesised with the aim to produce potential anticancer drug able to conjugate cytostatic activity with lack of nephrotoxicity. This complex contains: (1) an amino ligand; (2) a good leaving group (halide); and (3) an S-containing chelating agent potentially able to protect the metal centre from its interaction with S-containing protein-legating sites that are believed to be at the basis of the nephrotoxicity of Pt(II)-based drugs. This complex has been found to be effective as an antiproliferative agent (more active than cis-platin) towards a normal human adenocarcinoma cell line and the corresponding cis-platin-resistant C13 strain. Toxicity tests on the kidney were performed by means of a renal cortical slice model. The slices, prepared with a Brendel-Vitron slicer, were incubated with different doses (0.125-5.0 x 10(-4) M, final concentration) of [Pt(ESDT)(Py)Cl] or cis-platin dissolved in methyl sulphoxide. The platinum(II) complex showed very low renal cytotoxicity as compared with cis-platin; in particular, lipid peroxidation induced by cis-platin appeared about five-fold higher than that induced by [Pt(ESDT)(Py)Cl]. In conclusion, besides being less toxic for the kidney, the results showed that the new synthesised platinum(II) complex appeared in vitro more effective than cis-platin when tested on sensitive and resistant cis-platin tumour cell lines.

Hepatitis B vaccination awareness and biological risk

BACKGROUND

Hepatitis B virus is a possible risk in persons exposed to biological risk at work. Vaccination is the only prevention against infection.

OBJECTIVES

A population of 1,408 employees of the University of Padua was investigated to define the immunological status for HBV and degree of awareness to hepatitis B vaccination.

METHODS

The subjects were subdivided according to sex, age (< or = 40 or > 40 years old), level of education (college graduates or lower), and the extent of biological risk (no risk, low or high risk). Clinical history questionnaires were used and measurement of hepatitis B markers was carried out.

RESULTS

The results showed that only 30.5% of the subjects had been vaccinated; among these, 90.2% showed a measurable level of anti-HBs antibodies, 8.2% showed anti-HBs antibodies lower than 10 IU/L, and 1.6% showed positive markers of previous infection. However, among non-vaccinated subjects 13.4% were positive for previous infection; in all subjects, prevalence of hepatitis B virus infection was 9.8%. The awareness to hepatitis B vaccination was altogether very low (30.5%), but females (44.2%), subjects less than 40 years of age (43.5%), college graduates (34.1%), and high risk exposed personnel (57.7%) were more likely to comply compared to male subjects (odds ratio 2.53), subjects more than 40 years of age (odds ratio 3.57), non-college graduates (odds ratio 1.65), or low risk exposed (odds ratio 13.42).

CONCLUSIONS

The variables considered appeared to influence awareness to vaccination. Owing to low awareness, an information campaign was started and 90% of the invited subjects were immunized.

Tubular segment-specific biomarkers of nephrotoxicity in the rat

Segment-specific localization of p-aminohippuric acid accumulation and glutamine synthetase activity along the proximal tubule was investigated in kidneys of rats treated with segment-specific nephrotoxicants such as potassium dichromate (pars convoluta) and hexachloro-1:3-butadiene (pars recta). Potassium dichromate and the highest dose (200 mg/kg b.w.) of hexachloro-1:3-butadiene caused a significant, dose-dependent decrease of p-aminohippuric acid uptake in the renal cortical slices 24 and 48 h after the treatment. In contrast, hexachloro-1:3-butadiene and only the highest dose (40 mg/kg b.w.) of potassium dichromate, caused a significant dose-dependent decrease of glutamine synthetase activity in the kidney beginning 24 h after treatment. Finally, potassium dichromate and the highest dose (200 mg/kg b.w.) of hexachloro-1:3-butadiene (48 h after the treatment) caused a significant dose-dependent loss of kidney protein content. The results suggest that p-aminohippuric acid accumulation is localized in the pars convoluta and confirm that glutamine synthetase is in the pars recta of the rat proximal tubule. p-Aminohippuric acid uptake impairment and glutamine synthetase activity loss caused by the highest doses of hexachloro-1:3-butadiene and potassium dichromate, respectively, suggests that high doses of segment-specific chemicals may involve other portions of the proximal tubule; in addition, the decrease of glutamine synthetase activity caused by potassium dichromate may be related to the protein content loss.

Haemolytic anaemia after oral self-giving of naphthalene-containing oil

A clinical case of suicide attempt by means of oral self-giving of naphthalene-containing oil in an old man was reported. Clinical features showed haemolytic anaemia supported by a decrease of haemoglobin concentration and red blood cell count, an increase of bilirubin (prevalently indirect) and lactate dehydrogenase and very low levels of haptoglobin. Methaemoglobin (metHb) measured at admission to the Emergency Room and 19 days after poisoning was still above normal limits. No deficiency of glucose-6-phosphate dehydrogenase was detected. The clinical manifestations ameliorated after treatment with concentrated red blood cells and ascorbic acid, with fast normalization of metHb. The clinical picture appeared almost normal 1 month after poisoning. The clinical diagnosis was 'haemolytic anaemia caused by naphthalene'. Absence of glucose-6-phosphate dehydrogenase deficiency probably reduced the severity of poisoning.

Historical control data on urinary and renal tissue biomarkers in naive male Wistar rats

Total proteins, angiotensin-converting enzyme, N-acetyl-beta-D-glucosaminidase, glutamine transaminase K and glutamine synthetase were determined in urine collected overnight (14 h: 6:00 p.m.-8:00 a.m.) from naive male Wistar rats; glutamine transaminase K and glutamine synthetase in the kidney 10,000 g supernatant and p-aminohippurate uptake in renal cortical slices also were measured. Urinary parameters were related both to urinary creatinine concentration and urinary flow rate; kidney parameters were related to protein concentration (enzymes) or slice/medium (S/M) ratio (p-aminohippurate uptake). The following reference ranges (1.0 and 99.0 percentiles) were obtained: urine: total urinary proteins (195 samples) 0.03-0.29 g mmol(-1) creatinine and 0.13-1.77 mg h(-1); angiotensin-converting enzyme (115 samples) 8.9-63.7 micromol mmol(-1) creatinine and 59.4-282.7 nmol h(-1); glutamine transaminase K (115 samples) 0-1.7 micromol mmol(-1) creatinine and 0-8.5 nmol h(-1); N-acetyl-beta-D-glucosaminidase (72 samples) 0.7-5.0 micromol mmol(-1) creatinine and 4.9-28.4 nmol h(-1) (naive male rats did not excrete glutamine synthetase); kidney: glutamine transaminase K (36 samples) 14.5-32.8 nmol mg(-1) protein; glutamine synthetase (22 samples) 13.9-48.6 nmol mg(-1) protein and p-aminohippurate (54 samples) 4.77-17.89 S/M. Urinary creatinine (r = -0.780), total urinary proteins (r = -0.521), angiotensin-converting enzyme (r = -0.650) and N-acetyl-beta-D-glucosaminidase (r = -0.796) but not glutamine transaminase K were well correlated with diuresis. In addition, the same parameters, but not glutamine transaminase K, were well correlated with creatinine (r = 0.604,0.701 and 0.747, respectively). Significant correlation also was observed between urinary indices adjusted to creatinine or urinary flow rate (total urinary proteins: r = 0.813; angiotensin-converting enzyme: r = 0.677; glutamine transaminase K: r = 0.939; N-acetyl-beta-D-glucosaminidase: r = 0.657). Finally, a low but significant correlation was found between total urinary proteins and angiotensin-converting enzyme (r = 0.293) and N-acetyl-beta-D-glucosaminidase (r = 0.471).

Adjustment to concentration-dilution of spot urine samples: correlation between specific gravity and creatinine

OBJECTIVE

Spot urine samples were investigated to determine correlations between urinary creatinine and specific gravity, and intra- and inter-day variations other than gender- and age-dependence of urinary concentrations.

METHODS

Urinary creatinine concentrations and specific gravity were determined in 534 spot samples (385 from men and 149 from women). Subjects' ages ranged between 18 and 68 years. Spot urine samples were also collected from 14 male subjects before and after a 1-week work-shift for the evaluation of intra- and inter-day variations of creatinine and specific gravity.

RESULTS

In spot samples, creatinine concentrations ranged between 0.16 and 4.36 g/l and specific gravity between 1.002 and 1.037. A high correlation (r = 0.82, P < 0.001) was observed between creatinine and specific gravity; male subjects showed significantly higher values of creatinine (P < 0.001) than did female subjects (1.90 +/- 0.74 and 1.41 +/- 0.72 g/l, respectively) and specific gravity (1.023 +/- 0.006 and 1.020 +/- 0.007, respectively). In addition, creatinine but not specific gravity significantly decreased (P < 0.02) in subjects older than 50 years, compared with those under 40.

CONCLUSIONS

Results confirm the gender-dependence of creatinine concentrations in spot specimens and also show age-dependence, indicating the need for these aspects to be considered when the range of acceptable samples is to be set. No significant intra- or inter-day variations were observed for the two parameters. Lastly, the possibility of a comparison of differently adjusted values was indicated by a conversion formula derived from adjustments to creatinine and the corresponding specific gravity of a hypothetical urinary value, as follows: specific gravity adjusted values = 1.48 x creatinine adjusted values.

Monitoring human cytomegalovirus viral load in peripheral blood leukocytes of renal transplant recipients by a simple limiting dilution-PCR assay

To assess the clinical relevance of a semi-quantitative measurement of human cytomegalovirus (HCMV) DNA in renal transplant recipients within the typical clinical context of a developing country where virtually 100% of both receptors and donors are seropositive for this virus, we have undertaken HCMV DNA quantification using a simple, semi-quantitative, limiting dilution polymerase chain reaction (PCR). We evaluated this assay prospectively in 52 renal transplant patients from whom a total of 495 serial blood samples were collected. The samples scored HCMV positive by qualitative PCR had the levels of HCMV DNA determined by end-point dilution-PCR. All patients were HCMV DNA positive during the monitoring period and a diagnosis of symptomatic infection was made for 4 of 52 patients. In symptomatic patients the geometric mean of the highest level of HCMV DNAemia was 152,000 copies per 10(6) leukocytes, while for the asymptomatic group this value was 12,050. Symptomatic patients showed high, protracted HCMV DNA levels, whereas asymptomatic patients demonstrated intermittent low or moderate levels. Using a cut-off value of 100,000 copies per 10(6) leukocytes, the limiting dilution assay had sensitivity of 100%, specificity of 92%, a positive predictive value of 43% and a negative predictive value of 100% for HCMV disease. In this patient group, there was universal HCMV infection but relatively infrequent symptomatic HCMV disease. The two patient groups were readily distinguished by monitoring with the limiting dilution assay, an extremely simple technology immediately applicable in any clinical laboratory with PCR capability.

Glutamine synthetase activity in rat urine as sensitive marker to detect S3 segment-specific injury of proximal tubule induced by xenobiotics

The possibility of detecting segment-specific injury of the proximal tubule by means of urinary enzymes was investigated in rats. Urinary glutamine synthetase, an enzyme exclusively localized in the S3 segment, and N-acetyl-beta-D-glucosaminidase, prevalently a S1-S2, but S3 enzyme also, were determined after single treatment with 100 mg/kg body wt. of hexachloro-1:3-butadiene (HCBD; i.p.), toxic for the S3 segment, or 25 mg/kg body wt. of potassium dichromate (s.c.), toxic for the S1-S2 segments. Excretion of total urinary proteins was also measured. In addition, a dose-response relationship was determined between three doses (50, 100 and 200 mg/kg body wt.) of HCBD and glutamine synthetase activity in urine. Glutamine synthetase activity, measured according to a new assay for urine based on modification of methods developed for organs, increased in the urine only when the S3 segment of the proximal tubule was damaged, as demonstrated by histological findings of the kidneys. HCBD caused early excretion of the enzyme related to the necrosis of the S3 segment, whereas potassium dichromate caused a slight increase only when the resulting lesion to this segment (vacuolization) began to develop. On the contrary, N-acetyl-beta-D-glucosaminidase activity showed the peak of excretion 24 and 34 h after treatment with HCBD or potassium dichromate, respectively, according to the histological findings of necrosis of the S3 segment (the former) and vacuolization of the S1-S2 segments (the latter). Excretion of total urinary proteins reached the peak 24 h (HCBD) and 48 h (potassium dichromate) after treatment. HCBD at 200 mg/kg body wt, caused a peak of glutamine synthetase activity in urine 10 h after injection, whereas the peak caused by doses of 50 and 100 mg/kg body wt. occurred 24 h following treatment. The peak of enzyme activity in urine significantly increased with the dose. The results suggest that the measurement of urinary activity of S3 segment-specific enzyme as glutamine synthetase allows us to detect early S3 segment-specific injury of the proximal tubule. In addition, the method for urinary enzyme activity appears sensitive, simple and fast.

Risk of hepatitis C virus infection in a population exposed to biological materials

BACKGROUND

Hepatitis C virus is an important cause of acute and chronic hepatitis and it is an agent parenterally transmitted. Workers handling biological materials may be exposed to high concentration of virus-infected fluids.

METHODS

The seroprevalence of hepatitis C virus antibodies was investigated in a population of 809 subjects exposed to varying levels of biological risk owing to the handling of human fluids or tissues and in 408 controls. The exposed group was subdivided in three subgroups according to low and occasional (262), intermediate but continuous (311), and high (236) exposure to biological materials.

RESULTS

The seroprevalence of hepatitis C antibodies was low (1.40%) in all subjects. The risk groups showed no significant differences with respect to the control group; the most exposed group showed a seroprevalence of 1.27%. Age but not sex appeared significantly correlated with seroprevalence of positive antibodies (chi 2 = 5.949, P < 0.025). Aspartate aminotransferase and alanine aminotransferase showed a highly significant increase (P < 0.01 and P < 0.001, respectively) in subjects with positive hepatitis C antibodies, other than a high significant prevalence of values above the normal limit (chi 2 = 26.613, P < 0.001 and chi 2 = 39.164, P < 0.001, respectively). Among 17 positive hepatitis C virus subjects, 8 (47.1%) were positive for hepatitis B virus, but not for its antigen.

CONCLUSIONS

Hepatitis C virus infection appears to be a low risk for people employed in the biomedical field, yet infection is associated with a significant liver involvement.

Seroprevalence of hepatitis A markers in subjects exposed to biological risk

OBJECTIVES

The seroprevalence of hepatitis A virus antibodies was investigated in a population of 1051 subjects, of whom 376 were controls and 675 were exposed to different degrees of biological risk.

METHODS

The exposed group was subdivided into subjects at low (242), intermediate (265), and high (168) biological hazard; all subjects were employed in the biomedical field. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were also determined.

RESULTS

The seroprevalence of positive hepatitis A antibodies was 44.9% in all subjects but was significantly higher in males (50.6%) than in females (34.2%) and increased according to age (25.9% in subjects aged < or =40 years and 62.2% in subjects aged >40 years). No difference related to exposure to the biological risk was observed. The prevalence of transaminases at levels above normal values (chi2 = 4.079, P<0.05 for AST and chi2 = 4.806, P<0.05 for ALT) and mean values (AST P<0.05; ALT P<0.001) appeared significant in hepatitis A virus-positive subjects. On the other hand, excluding individuals with positive hepatitis C virus antibodies (16) and positive hepatitis B virus surface antigen (12), a prevalence of transaminase alterations was not observed, but mean levels of ALT lasted significantly longer in subjects with positive hepatitis A virus antibodies (P<0.01).

CONCLUSIONS

The results confirm that hepatitis A virus is not a risk for employees in the biomedical field, but the presence of hepatitis A virus antibodies suggests a possible, though not clinically evident, liver involvement.

Different effects of (CIS+TRANS) 1,3-dichloropropene in renal cortical slices derived from male and female rats

Nephrotoxic effects of 1,3-dichloropropene (cis and trans isomers mixture) was investigated in vitro by means of renal cortical slice model in male and female rats, including treatment with metabolism modifiers as an inducer of cytochrome P-450 1A class (beta-naphthoflavone), a reduced glutathione depleting (DL-buthionine-[S,R]-sulfoximine), an inhibitor of gamma-glutamyl-transferase (AT-125) and inhibitor of cysteine conjugate beta-lyase (aminooxiacetic acid). Dose-dependent decrease of p-aminohippurate uptake was observed in male renal cortical slices. Only the high doses (3.0 and 4.0 x 10(-4) M) caused a significant loss of organic anion uptake in females. beta-Naphthoflavone and alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (AT-125) partially, but significantly, reduced organic anion loss in males. In females, DL-buthionine-[S,R]-sulfoximine significantly increased in females but in males loss of organic anion accumulation caused by 1,3-dichloropropene. Aminooxyacetic acid did not ameliorate 1,3 D effects in vivo and in vitro in male rats. It appeared very toxic for female rats (all rats died) after in vivo injection. Sensitivity to nephrotoxicity induced by 1,3-dichloropropene in vitro was about double in male than female rats. Reduced glutathione conjugation appeared involved in nephrotoxicity induced in males but in females, probably by means of a chloropropyl-cysteinylglycine-conjugate formation; slight toxicity in females is likely related to oxidative metabolism.

Glutamine transaminase K intranephron localization in rats determined by urinary excretion after treatment with segment-specific nephrotoxicants

Glutamine transaminase K(GTK) excretion assessed in urine and by kidney histology was evaluated in rats after single treatment with 1.0 mg/kg i.p. of mercuric chloride, 100 mg/kg i.p. of hexachloro-1:3-butadiene (both S3, pars recta, segment-specific nephrotoxicants) and 25 mg/kg s.c. of potassium dichromate (S1-S2, pars convoluta, segment-specific nephrotoxicant). The aim was to correlate segment-specific injury and enzyme excretion in order to assess, using non-vasive methods, localization of GTK along the proximal tubule. Mercuric chloride and hexachloro-1:3-butadiene produced early focal damage in the pars recta (focal necrosis was shown 10 h after treatment, and diffuse necrosis appeared later at 34 and 24 h after treatment). Changes of the pars convoluta were occasional and delayed (72 h after treatment for both substances). On the contrary, potassium dichromate induced damage of the pars convoluta (vacuolar degeneration and focal necrosis were evident 24 h and 48 h after treatment, respectively), whereas the pars recta was affected later (focal vacuolar degeneration was observed 72 h after treatment). Increase urinary GTK excretion was early after treatment with mercuric chloride and hexachloro-1:3-butadiene (significant increase was observed within 10 h), with a peak for both substances 24 h after treatment, in agreement with the necrosis of the pars recta. Potassium dichromate induced a significant increase of enzyme excretion in urine also 24 h after injection, according to histological features showing vacuolar degeneration of the pars convoluta; the peak of excretion was reached 48 h after treatment (delay was due, probably, to s.c. administration). The results show that GTK increased in urine after treatment with S3 and S1-S2 specific nephrotoxicants; the combination of histological examination and urinary enzyme supports the evidence that the enzyme is distributed along the whole of the proximal tubule.

Conceptual translation of timeless reveals alternative initiating methionines in Drosophila

We have sequenced genomic fragments which encode the N-terminus of the TIMELESS (TIM) clock protein in Drosophila simulans and D. yakuba. We observe that in these two species, the initiating methionine appears to lie downstream of the one proposed to encode the translational start inD.melanogaster, thereby truncating the N-terminus by 23 amino acids. We then sequenced the corresponding 5'fragment in a number of D. melanogaster individuals from different strains. We observed a polymorphism which strongly suggests that the originally proposed start site cannot be utilised in some individuals, and that these flies will initiate translation of TIM at the downstream ATG. Given the current interest in TIM regulation in D. melanogaster, it is important to correctly define the N-terminus in this species.

Influence of hormone status on enzymes released from renal cortical slices of Wistar rats

Release of some cytosolic (aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase) and brush border (gamma-glutamyltransferase and alkaline phosphatase) enzymes from renal cortical slices was studied in vitro. Renal cortical slices were prepared freehand from 3-month-old male and female Wistar rats of different hormonal status. Some male and female rats were castrated at 1 month of age and a portion of castrated males and of naive males and females were s.c. treated with testosterone (10 mg kg-1 body wt.) on alternate days for 3 weeks. Females had higher alanine aminotransferase (77.5 +/- 2.8 nmol 100 mg-1 tissue), lactate dehydrogenase (5.01 +/- 0.24 mumol) and alkaline phosphatase (1.63 +/- 0.15 mol) activities than male rats (20.4 +/- 0.9, 3.99 +/- 0.19 and 0.91 +/- 0.02, respectively). On the contrary, aspartate aminotransferase and gamma-glutamyltransferase were similar. Among cytosolic enzymes, alanine aminotransferase and lactate dehydrogenase appeared to be sexual hormone-dependent enzymes: castration significantly increased enzyme activities in males (49.6 +/- 1.1 for the former; 5.30 +/- 0.15 for the latter) and caused significant decreases in females (alanine aminotransferase only 47.1 +/- 1.5), whereas testosterone pretreatment decreased activities in cortical slices from female (48.1 +/- 3.6 and 3.81 +/- 0.07, respectively) and castrated male (27.4 +/- 1.8 and 4.05 +/- 0.15, respectively). Moreover, exogenous testosterone increased aspartate aminotransferase in males (1.05 +/- 0.01 mumol) and castration increased it in both sexes. The activity of brush border enzymes was increased by testosterone pretreatment and decreased by castration (mainly alkaline phosphatase).

Mechanism of sex-related differences in nephrotoxicity of 1.2-dichloropropane in rats

The contribution of testosterone to the nephrotoxic effects of 1,2-dichloropropane (DCP) was assessed by a series of castration and sex hormone replacement experiments on Wistar rats. The nephrotoxic action of DCP was evaluated by measuring the accumulation of organic anion and release of aspartate aminotransferase into the incubation medium using a renal cortical slice model. Our data show that sex, castration, and testosterone pretreatment are factors that influence the effect of DCP on renal cortical slices of rats Males appear to be more sensitive to nephrotoxic effects of DCP than females, male castration prevents the nephrotoxic effects of DCP, and pretreatment of females and castrated males with testosterone increases the susceptibility to DCP. In this study an attempt was made to evaluate the role of sex differences in the expression of enzymes participating in Phase I and Phase II detoxication reactions in order to explain the differences in sensitivity of the two genders to the nephrotoxic action of DCP. Our results implicate gender-specific expression of cytochrome P-450 in the kidneys as a predominant factor that determines the different susceptibilities of male and female rats to the nephrotoxic effect of DCP. We propose that the oxidation of DCP by CYP IIE1 is the first saturable and limiting step in the metabolic activation of DCP to nephrotoxic metabolites. It appears that, despite the fact that the nephrotoxic effect of DCP is determined mainly by its cysteine-conjugated metabolites, gluthathione (GSH) content and glutathione S-transferase (GST) activity in kidney are not directly related to increased androgen-related susceptibility to DCP.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological monitoring of cadmium exposure: reliability of spot urine samples

Concentration-dilution of spot urine samples is a shortcoming of the biological monitoring of industrial xenobiotics. To ascertain whether the adjustment of urinary cadmium measured in spot samples is appropriate, urine samples were taken three times, once a week for 3 successive weeks, from 25 welders employed in the manufacture of jewelry (total 75 samples). Cadmium, creatinine, specific gravity, total urinary solutes, urinary volume and urinary flow rate were measured in 12-h collections and in spot samples taken immediately afterwards. Creatinine and total urinary solutes showed high inverse correlation with urinary flow rate (r = -0.858 and r = -0.768 respectively). Urinary cadmium displayed a similar trend but the correlation was not significant (r = -0.145). Creatinine adjustment of urinary cadmium values in spot samples increased the correlation with the same index in timed samples adjusted for urinary volume (r = -0.808) or urinary flow rate (r = 0.821) compared with non-adjustment (r = 0.732 and r = 0.738, respectively). Creatinine adjustment of spot sample values is also suitable for a wide range of urinary concentrations; discarding excessively diluted or concentrated urines, correlation of urine samples improved for non-adjusted or specific gravity-adjusted values, whereas no changes were observed for creatinine-adjusted values.

Care of the adult patients with cystic fibrosis

Although no therapeutic breakthrough has taken place, the life expectancy of patients with cystic fibrosis (CF) has dramatically increased in the last 20 yrs. Nowadays, more than 80% of the patients outlive 18 yrs of age, with a mean survival age approaching 28 yrs. These favourable results are due mainly to early diagnosis and continuous treatment in specialized centres. The main therapeutic items are: prevention and early treatment of lung infections, mainly due to Pseudomonas aeruginosa, drainage of bronchial secretions (postural drainage, forced expiratory techniques, positive-expiratory-pressure mask, autogenic drainage,...), substitutive therapy with pancreatic enzymes and hypercaloric diet. Thus cystic fibrosis is increasingly a disease which involves adults, with many related problems, which span from the difficulties of prescribing an effective antibiotic therapy in cases with multiple resistances, to combining the need for a long daily physiotherapy schedule with school or a working life. Sexual problems and related psychological troubles are an important issue in the management of cystic fibrosis in adult patients, and are accordingly treated.

In-vitro mechanisms of 1,2-dichloropropane nephrotoxicity using the renal cortical slice model

1. Renal cortical slices isolated from the kidneys of male Wistar rats were used as an experimental model for studying the nephrotoxicity induced by 1,2-dichloropropane. 2. The solvent causes a depletion of renal reduced glutathione content and slight, but significant, lipid peroxidation. The block of the oxidative pathway with carbon monoxide prevents glutathione content depletion, and shows that this conjugation is the major step in 1,2-dichloropropane metabolism. 3. Loss of organic anion accumulation and release into the incubation medium of tubular enzymes, mainly from the soluble fraction, are the toxic effects of the solvent. The brush border is only slightly affected. 4. The mechanism of nephrotoxicity appears to occur via mercapturic acid metabolism. Acivicin and aminooxyacetic acid, inhibitors of gamma-glutamyltransferase and beta-lyase activity, respectively, partially but significantly prevent the loss of organic anion accumulation induced by 1,2-dichloropropane. Furthermore, alpha-ketobutyrate, an activator of beta-lyase, enhances the effects of 1,2-dichloropropane on the target, but is itself toxic for organic anion accumulation.

Sex- and age-related nephrotoxicity due to 1,2-dichloropropane in vitro

Sex- and age-related nephrotoxicity due to 1,2-dichloropropane was studied in vitro by means of renal cortical slices obtained from Wistar rats. Reduced glutathione content, organic anion accumulation (p-aminohippurate), and release of malondialdehyde (to measure the extent of lipid peroxidation), aspartate aminotransferase, gamma-glutamyltransferase and lactate dehydrogenase into the incubation medium were determined. Sex differences in naive rats parameters were slight, but male were more susceptible to toxic effects of 1,2-dichloropropane than female rats; glutathione depletion, lipid peroxidation, and loss of organic anion accumulation were higher in male than in female slices. During senescence, naive male rats showed a progressive decrease of glutathione content (statistically significant from 7-9 months of age), increase of spontaneous lipid peroxidation from the same age, and increase of signs of cytotoxicity (release of aspartate aminotransferase and lactate dehydrogenase into the incubation medium) from 3-4 months of age. A loss of organic anion accumulation started from 7-9 months of age. Slices from rats of 3-4 months old showed the apparently highest susceptibility to 1,2-dichloropropane but depletion of glutathione content and loss of organic anion accumulation were at the same level in the oldest rats. The age decrease of control values caused the differences in the percentage ratio and then, apparently, a lower DCP effect. On the contrary, the increase of aspartate aminotransferase released in the incubation medium by DCP-treated slices corresponded to the age-related increase in cytotoxicity.

[Biological indicators of the renal involvement in workers with previous exposure to cadmium: a 5-year follow up]

Six welders who had been exposed to high cadmium concentrations were monitored for 5 years after cessation of exposure. Indicators of exposure and effect had shown marked alterations during exposure, with 3 subjects showing low molecular weight proteinuria (beta 2-microglobinuria), one of whom with total proteinuria as well. During the follow-up period, beta 2-microglobinuria increased up to a maximum in 2 subjects; in another subject, after a temporary increase, beta 2-microglobinuria returned to normal levels after 5 years. Urinary enzyme excretion had exceeded normal values during exposure; during the follow-up, brush border enzyme excretion was persistently high (only angiotensin converting enzyme activity showed a progressive reduction), whereas cytoplasmatic enzyme values returned to normal one year after cessation of exposure.

Recovery of biochemical changes induced by 1,2-dichloro propane in rat liver and kidney

1. Biochemical changes in male, Wistar rats, treated with different doses of 1,2-dichloropropane (50-500 mg kg-1 body weight), were investigated at the end of a 4-week treatment and after a 4-week recovery period. 2. The behaviour of Phase I and Phase II metabolic steps and of the angiotensin converting enzyme activity of the renal proximal tubule brush border were determined. 3. Phase II is more affected by the solvent than Phase I metabolism, and liver metabolism is more affected than the kidney. 4. Angiotensin converting enzyme activity from the proximal tubule brush border appears to be the most sensitive parameter of kidney involvement during treatment. 5. After a 4-week recovery period all the metabolic indices together with angiotensin converting enzyme activity have returned to normal. Only liver reduced glutathione content shows a slight, but significant, increase for the highest dose (500 mg kg-1 body weight). 6. The results show that the biochemical changes induced in liver and kidney by 1,2-dichloropropane are reversible.

Biological monitoring of nitrous oxide exposure in surgical areas

Exposure to nitrous oxide in surgical theaters was evaluated for duration, numbers, and types of surgical procedures. The concentration of the gas in the air was 92-444 ppm. Before and after the surgical sessions, samples of urine and expired air were collected from surgical theater personnel for gas determination. Nitrous oxide concentrations in urine and in expired air showed a good correlation with gas concentration in the air (r = 0.760 and r = 0.921, respectively). Moreover, a good correlation (r = 0.823) between gas concentration in urine and that in expired air was also found. A biological threshold limit value (TLV) of 20.6 micrograms/liter for urine and of 29.6 ppm for expired air was calculated, based on the limit of 50 ppm in the air proposed by the American Conference of Governmental Industrial Hygienists (ACGIH). Other biological TLVs corresponding to higher proposed limits (200 and 500 ppm) were also calculated.

Concentration adjustment of spot samples in analysis of urinary xenobiotic metabolites

The reliability of the adjustment for the reduction of concentration-dilution effects in urinalysis of spot specimens was evaluated; 95.4% of spot specimens showed a creatinine concentration between 0.5 and 3 g/liter, whereas 59.8% showed a specific gravity between 1.010 and 1.030. Only 6% of the specimens exceeded the specific gravity of 1.035 corresponding to a creatinine concentration of 3 g/liter. Therefore, an acceptable value for specific gravity in spot specimens of 1.035 is proposed. Although either specific gravity or creatinine provides a reliable mean of adjustment, creatinine is preferred because it has fewer physiological confounding factors.

Chromosomal aberrations, sister chromatid exchanges, and urinary thioethers in nurses handling antineoplastic drugs

In this study we examined the structural chromosomal aberrations (CA) and sister chromatid exchanges (SCE) of 12 nurses handling moderate quantities of antineoplastic drugs. Urinary thioethers were also measured to assess the potential exposure to alkylating drugs. Two control groups with similar mean age and smoking habits and working in the same hospital were also studied: 1) control clerks and 2) control nurses. Our study did not show any clear increase of chromosomal damage in exposed nurses as compared to controls. However, CA in control nurses were significantly increased (p = 0.05) with respect to control clerks. The results of baseline urinary excretion of thioethers were statistically higher (p less than 0.02) in exposed subjects than in control clerks.