The effect of hypoxic ischemic encephalopathy towards multi-organ complications and its early outcome at a Malaysian district hospital

INTRODUCTION

Hypoxic ischemic encephalopathy (HIE) is a clinically defined syndrome of disturbed neurologic function in the newborn with evidence of perinatal asphyxia. Stages of HIE are categorised into mild, moderate or severe based on the Sarnat classification. Neurological dysfunction constitutes a part of the wide spectrum of hypoxic ischemic insult as affected infants can have co-existing multi-organ dysfunction which further contributes to morbidities and mortality. This study aims to determine the relationship between the severity of HIE with multi-organ complications and early clinical outcomes.

MATERIALS AND METHODS

All neonates who were admitted to the NICU at Hospital Sultan Abdul Halim between January 2018 to December 2022, who fulfilled the inclusion criteria were included. Demographic data, clinical course and investigation results were retrospectively obtained from the medical records.

RESULTS

From a total of 90 infants (n = 90) who fulfilled our inclusion criteria, 31 (34%) were mild, 31 (34%) were moderate and 28 (31%) were severe HIE. The mean maternal age was 27 years. Common antenatal issues include diabetes mellitus (37.8%) and anaemia (22.2%). The Apgar scores at 1 and 5 minutes, initial resuscitation requiring intubation, chest compression and adrenaline were associated with higher severity of HIE (p < 0.05). Coagulation dysfunction was the most common complication (79.7%), followed by respiratory dysfunction (33.3%), cardiac dysfunction (28.9%), renal dysfunction (16.1%), haematological dysfunction (15.6%) and hepatic dysfunction (12%). Respiratory and haematological dysfunctions were significantly associated with higher mortality (p < 0.05). There was a significant longer hospital stay (p = 0.023), longer duration of ventilation (p < 0.001) and increase in frequency of seizures (p < 0.001) when comparing moderate and severe HIE patients to mild HIE patients. With increasing severity of HIE, there was also statistically significant higher mortality (p < 0.001).

CONCLUSIONS

There is a significant relationship between multiorgan dysfunction, the severity of HIE and mortality. Early anticipation of multi-organ injury is crucial for optimal early management which would reduce the mortality and improve the neurological outcome of the patients.

A deep learning-based technique for the diagnosis of epidural spinal cord compression on thoracolumbar CT

PURPOSE

To develop a deep learning (DL) model for epidural spinal cord compression (ESCC) on CT, which will aid earlier ESCC diagnosis for less experienced clinicians.

METHODS

We retrospectively collected CT and MRI data from adult patients with suspected ESCC at a tertiary referral institute from 2007 till 2020. A total of 183 patients were used for training/validation of the DL model. A separate test set of 40 patients was used for DL model evaluation and comprised 60 staging CT and matched MRI scans performed with an interval of up to 2 months. DL model performance was compared to eight readers: one musculoskeletal radiologist, two body radiologists, one spine surgeon, and four trainee spine surgeons. Diagnostic performance was evaluated using inter-rater agreement, sensitivity, specificity and AUC.

RESULTS

Overall, 3115 axial CT slices were assessed. The DL model showed high kappa of 0.872 for normal, low and high-grade ESCC (trichotomous), which was superior compared to a body radiologist (R4, κ = 0.667) and all four trainee spine surgeons (κ range = 0.625-0.838)(all p < 0.001). In addition, for dichotomous normal versus any grade of ESCC detection, the DL model showed high kappa (κ = 0.879), sensitivity (91.82), specificity (92.01) and AUC (0.919), with the latter AUC superior to all readers (AUC range = 0.732-0.859, all p < 0.001).

CONCLUSION

A deep learning model for the objective assessment of ESCC on CT had comparable or superior performance to radiologists and spine surgeons. Earlier diagnosis of ESCC on CT could reduce treatment delays, which are associated with poor outcomes, increased costs, and reduced survival.

5-alpha reductase inhibitors and MRI prostates: actively reducing prostate sizes and ambiguity

BACKGROUND

Magnetic resonance imaging (MRI) scans are increasingly first-line investigations for suspected prostate cancer, and essential in the decision for biopsy. 5-alpha reductase inhibitor (5-ARI) use has been shown to reduce prostate size and prostate cancer risk. However, insufficient data exists on how 5-ARI use affects MRI findings and yield of biopsy. This study explores the differences in imaging and prostate cancer diagnoses between patients receiving and not receiving 5-ARI therapy.

METHODS

From 2015 to 2020, we collected retrospective data of consecutive patients undergoing prostate biopsy at one centre. We included patients who were biopsy-naïve, had prior negative biopsies, or on active surveillance for low-grade prostate cancer. Clinical and pathological data was collected, including 5-ARI use, Prostate Imaging Reporting and Data System (PIRADS) classification and biopsy results.

RESULTS

351 men underwent saturation biopsy with or without targeted biopsies. 54 (15.3%) had a history of 5-ARI use. On mpMRI, there was no significant difference between the 5ARI and non-5-ARI groups in PIRADS distribution, number of lesions, and lesion location. Significantly fewer cancers were detected in the 5-ARI group (46.3% vs. 68.0%; p < 0.01). There were no significant differences in PIRADS distribution in 5-ARI patients with positive and negative biopsy.

CONCLUSION

Our study found significant differences in biochemical, imaging and biopsy characteristics between 5-ARI and non-5-ARI groups. While both groups had similar PIRADS distribution, 5-ARI patients had a lower rate of positive biopsies across all PIRADS categories, which may suggest that the use of 5ARI may confound MRI findings. Further studies on how 5-ARI therapy affects the imaging characteristics of prostate cancer should be performed.

Deep learning assessment compared to radiologist reporting for metastatic spinal cord compression on CT

Introduction

Metastatic spinal cord compression (MSCC) is a disastrous complication of advanced malignancy. A deep learning (DL) algorithm for MSCC classification on CT could expedite timely diagnosis. In this study, we externally test a DL algorithm for MSCC classification on CT and compare with radiologist assessment.

Methods

Retrospective collection of CT and corresponding MRI from patients with suspected MSCC was conducted from September 2007 to September 2020. Exclusion criteria were scans with instrumentation, no intravenous contrast, motion artefacts and non-thoracic coverage. Internal CT dataset split was 84% for training/validation and 16% for testing. An external test set was also utilised. Internal training/validation sets were labelled by radiologists with spine imaging specialization (6 and 11-years post-board certification) and were used to further develop a DL algorithm for MSCC classification. The spine imaging specialist (11-years expertise) labelled the test sets (reference standard). For evaluation of DL algorithm performance, internal and external test data were independently reviewed by four radiologists: two spine specialists (Rad1 and Rad2, 7 and 5-years post-board certification, respectively) and two oncological imaging specialists (Rad3 and Rad4, 3 and 5-years post-board certification, respectively). DL model performance was also compared against the CT report issued by the radiologist in a real clinical setting. Inter-rater agreement (Gwet's kappa) and sensitivity/specificity/AUCs were calculated.

Results

Overall, 420 CT scans were evaluated (225 patients, mean age=60 ± 11.9[SD]); 354(84%) CTs for training/validation and 66(16%) CTs for internal testing. The DL algorithm showed high inter-rater agreement for three-class MSCC grading with kappas of 0.872 (p<0.001) and 0.844 (p<0.001) on internal and external testing, respectively. On internal testing DL algorithm inter-rater agreement (κ=0.872) was superior to Rad 2 (κ=0.795) and Rad 3 (κ=0.724) (both p<0.001). DL algorithm kappa of 0.844 on external testing was superior to Rad 3 (κ=0.721) (p<0.001). CT report classification of high-grade MSCC disease was poor with only slight inter-rater agreement (κ=0.027) and low sensitivity (44.0), relative to the DL algorithm with almost-perfect inter-rater agreement (κ=0.813) and high sensitivity (94.0) (p<0.001).

Conclusion

Deep learning algorithm for metastatic spinal cord compression on CT showed superior performance to the CT report issued by experienced radiologists and could aid earlier diagnosis.

Improved Productivity Using Deep Learning-assisted Reporting for Lumbar Spine MRI

Background Lumbar spine MRI studies are widely used for back pain assessment. Interpretation involves grading lumbar spinal stenosis, which is repetitive and time consuming. Deep learning (DL) could provide faster and more consistent interpretation. Purpose To assess the speed and interobserver agreement of radiologists for reporting lumbar spinal stenosis with and without DL assistance. Materials and Methods In this retrospective study, a DL model designed to assist radiologists in the interpretation of spinal canal, lateral recess, and neural foraminal stenoses on lumbar spine MRI scans was used. Randomly selected lumbar spine MRI studies obtained in patients with back pain who were 18 years and older over a 3-year period, from September 2015 to September 2018, were included in an internal test data set. Studies with instrumentation and scoliosis were excluded. Eight radiologists, each with 2-13 years of experience in spine MRI interpretation, reviewed studies with and without DL model assistance with a 1-month washout period. Time to diagnosis (in seconds) and interobserver agreement (using Gwet κ) were assessed for stenosis grading for each radiologist with and without the DL model and compared with test data set labels provided by an external musculoskeletal radiologist (with 32 years of experience) as the reference standard. Results Overall, 444 images in 25 patients (mean age, 51 years ± 20 [SD]; 14 women) were evaluated in a test data set. DL-assisted radiologists had a reduced interpretation time per spine MRI study, from a mean of 124-274 seconds (SD, 25-88 seconds) to 47-71 seconds (SD, 24-29 seconds) (P < .001). DL-assisted radiologists had either superior or equivalent interobserver agreement for all stenosis gradings compared with unassisted radiologists. DL-assisted general and in-training radiologists improved their interobserver agreement for four-class neural foraminal stenosis, with κ values of 0.71 and 0.70 (with DL) versus 0.39 and 0.39 (without DL), respectively (both P < .001). Conclusion Radiologists who were assisted by deep learning for interpretation of lumbar spinal stenosis on MRI scans showed a marked reduction in reporting time and superior or equivalent interobserver agreement for all stenosis gradings compared with radiologists who were unassisted by deep learning. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Hayashi in this issue.

Urinary trans,trans-muconic acid determined by liquid chromatography: application in biological monitoring of benzene exposure

We describe a sensitive and specific high-performance liquid-chromatographic method for determining the benzene metabolite, trans,trans-muconic acid (ttMA) in urine by measuring ultraviolet absorbance at 265 nm. We mix 1 mL of urine sample with 2 mL of Tris buffer containing vanillic acid as internal standard (IS) and percolate this through a preconditioned ion-exchange column. After rinsing the column with phosphoric acid solution, acetate buffer, and deionized water, we elute the analytes with 2 mL of an equivolume solution of 1.5 mol/L sodium chloride and methanol. Of this, 5 microL is injected into the HPLC column. The mobile phase used consists of, per liter, 10 mL of acetic acid, 100 mL of methanol, and the rest 5 mmol/L sodium acetate. The flow rate was started at 1 mL/min and increased to 1.5 mL/min after 6 min. ttMA and IS were detected at 5.2 and 10.2 min, respectively. The lowest detection limit is 125 pg. Analytical recovery and reproducibility generally exceeded 90%. We validated the method with urine samples collected from normal persons and from refinery workers exposed to benzene concentrations &lt; 1 microL/L. The results show that urinary ttMA is a promising biological marker for risk assessment of low-concentration benzene exposure.

Oxygen consumption is increased relative to work rate in patients with McArdle's disease

BACKGROUND

Patients with McArdle's disease suffer exercise incapacity as a result of myophosphorylase deficiency, and for a given work rate have excessive circulatory and ventilatory responses. We hypothesized that the rate of increase of oxygen consumption with work rate (DeltaVO2-DeltaWR slope) would also be elevated in such patients as a result of these excessive responses.

PATIENTS AND METHODS

Five patients with McArdle's disease and five matched controls carried out a maximal incremental cardiopulmonary exercise test. Controls then carried out a second test matched to the maximal test of a paired patient. Venous blood was sampled at rest, peak exercise and recovery.

RESULTS

During the matched test, the DeltaVO2-DeltaWR slope was higher in the patients than in the controls [19.9 (15.0-24.6) vs. 11.7 (9.2-13.5) mL min(-1) W(-1); mean (range); P = 0.022], and the peak-achieved VO2 was also greater in the patient group [1201 (890-1575) vs. 918 (599-1248) mL min(-1); P = 0.003]. A similar pattern was observed for heart rate [173 (165-182) vs. 108 (105-134) b.p.m.; P = 0.001] and plasma norepinephrine levels [12.6 (9.2-19.9) vs. 2.9 (2.2-4.9) nmol l(-1); P = 0.003].

CONCLUSION

There is an increased rate of rise in VO2 relative to work rate during exercise in patients with McArdle's disease. There is also a greater rise in catecholamines, which may be the result of a physiological response to substrate starvation, and is likely to contribute to the increase in VO2.

Biological monitoring of kidney function among workers occupationally exposed to trichloroethylene

AIMS

To investigate the nephrotoxic potential of trichloroethylene in a currently exposed population using sensitive urinary markers of kidney toxicity.

METHODS

Renal dysfunction was monitored in a cross-sectional study of 70 workers currently exposed to trichloroethylene. An age and sex matched control population of 54 individuals was drawn from hospital and administrative staff.

RESULTS

The mean exposure to trichloroethylene, estimated from urinary trichloroacetic acid concentrations, was 32 ppm (range 0.5-252 ppm) with an average duration of exposure of 4.1 years (range 1-20 years). Significant differences between the exposed and control populations were found for nephrotoxicity markers N-acetylglucosaminidase (NAG) and albumin, and for the mode of action marker, formic acid. However, neither NAG nor albumin showed a significant correlation with either the magnitude or duration of exposure to trichloroethylene. There was a significant correlation between urinary formic acid and trichloroacetic acid concentrations. Within the exposed population there were dose dependent increases in urinary methylmalonic acid concentrations and urinary glutathione S-transferase alpha activity. Although still within the control range, these changes were clearly dose dependent and consistent with one of the proposed mechanisms of trichloroethylene induced kidney toxicity.

CONCLUSION

Although there was no evidence of kidney toxicity within the population studied, the results suggest that kidney damage could occur at exposure concentrations higher (>250 ppm) than those encountered in this study.

Can salivary lead be used for biological monitoring of lead exposed individuals?

BACKGROUND

Measurement of blood lead (BPb) is the usual method for biomonitoring of persons exposed to inorganic lead.

AIM

To explore the use of salivary lead (SPb) as an alternative.

METHODS

BPb and SPb levels were measured in a group of 82 lead exposed adults.

RESULTS

The mean BPb of the workers was 26.6 microg/dl (SD 8.6, range 10-48) and the mean SPb level 0.77 microg/dl, or 3% of the BPb level. As the SPb distribution was skewed, logarithmic transformation was performed to normalise the distribution. A bivariate scattergram of BPb and logSPb (r = 0.41, p = 0.00) had a line of best fit expressed as BPb = 29.7 + 8.95logSPb. The relation of logSPb and BPb was stronger among non-smokers (r = 0.42) compared to smokers (r = 0.3); and among those without a medical condition (r = 0.44). Multiple linear regression analysis (fitting smoking and medical condition into the model) yielded an R of 0.54, and an adjusted R(2) of 0.26.

CONCLUSION

The study findings do not support the use of SPb for biomonitoring at BPb levels ranging from 10 to 50 microg/dl.

Renal dysfunction in workers exposed to inorganic lead

INTRODUCTION

We studied the relationship between renal dysfunction and occupational lead exposure in a local factory.

MATERIALS AND METHODS

A cross-sectional study with a cohort component was conducted with 55 male workers of a factory producing PVC stabilisers as subjects. Workers from this factory have been followed up with 6-monthly blood lead measurements since 1982. Two indices of overall lead exposure, i.e. the number of times a worker's blood lead exceeded 40 micrograms/dL (PbB40) and cumulative blood lead index (PbBint), were obtained from this data. Recent blood lead concentration (PbB) was measured. 4-hour creatinine clearance and various other urinary and serum markers of renal dysfunction were used as effect indices.

RESULTS

There was no relationship between PbB and any of the renal markers. However, creatinine clearance decreased significantly (P < 0.001) with increasing PbB40 and PbBint after adjustment for age and smoking habits. Urinary albumin (Ualb), urinary alpha-1 microglobulin (U alpha 1m), urinary beta-2 microglobulin (U beta 2m) and urinary retinol-binding protein (URBP) increased significantly with both increasing PbB40 and PbBint. Total urinary activity of N-acetyl-beta-D-glucosaminidase (NAG-T) and its heat-stable isoenzyme (NAG-B) increased significantly with increasing PbB40. A significant difference in renal parameters occurred when PbB40 was 1 or more.

CONCLUSIONS

We have found a positive association between overall lead exposure and renal dysfunction. The renal parameters were significantly higher among those who had at least one episode of blood lead above 40 micrograms/dL. Our findings also strengthen the case for the use of Ualb, U alpha 1m, U beta 2m, URBP, NAG-T and NAG-B as early markers of lead nephropathy.

Are salivary immunoglobulin A and lysozyme biomarkers of stress among nurses?

Salivary immunoglobulin A (IgA) and lysozyme have been studied as possible biomarkers of stress. This study examined the stress levels among female nurses in various units and the relationship between these stress levels and salivary IgA and lysozyme secretion. One hundred ninety-five (43%) of 457 eligible female nurses from surgical wards/operating theaters (SURG), medical wards (MED), and outpatient clinics/day-surgery theaters (OPD) completed a self-administered questionnaire. From this group of 195 nurses, 124 provided a salivary sample accumulated over 5 minutes. Stress levels were assessed with a ten-point Stress Assessment Score (SAS) for Asians and a direct question on perceived life stress. Enzyme-linked immunosorbent assay and lyso-plate methods were used to determine salivary IgA and lysozyme levels. Forty-five percent of SURG, 35% of MED, and 17% of OPD nurses scored at least four points on the SAS. SURG nurses had the lowest IgA secretion (geometric mean; 95% confidence interval [CI]) rates (43 micrograms/min; 36 to 51 micrograms/min). The other groups had significantly higher salivary IgA secretion rates: MED (96 micrograms/min; 80 to 116 micrograms/min) and OPD (77 micrograms/min; 60 to 98 micrograms/min) Findings for salivary lysozyme (microgram/min) were similar; SURG (9 micrograms/min; 6 to 13 micrograms/min) MED (19 micrograms/min; 12 to 28 micrograms/min) and OPD (16 micrograms/min; 9 to 28 micrograms/min). The salivary IgA (Spearman's r = -0.22, P = 0.01) but not the lysozyme (Spearman's r = -0.01, P = 0.9) secretion rate correlated negatively with SAS. Nurses working in various units under different conditions experienced dissimilar levels of stress. Salivary IgA, but not lysozyme, correlated inversely with self-reported levels of stress. It may thus be a potential biomarker in future studies on stress.

Serum DDT and DDE levels in Singapore general population

A simple and fast method was used to determine 1,1'-(2,2,2-trichloroethylene)-bis(4-chlorobenzene) (DDT) and 1,1'-(2,2-dichloroethylidene)-bis(4-chlorobenzene) (DDE) in blood serum. Serum samples pre-treated with formic acid were extracted with n-hexane and determined by gas chromatography (GC-ECD), using PTE-5 capillary column. Detection limits for DDT and DDE were 0.5 ppb. Recovery with a fortified pooled sample at 1 ppb level was 107.0% for DDT and 106.0% for DDE. At 10 ppb level, the recoveries for DDT and DDE were 96.1% and 92.7%, respectively. Eighty-nine random blood samples collected from volunteers were analyzed. The geometric mean (GM) serum level of DDT was 1.9 ppb (0.2-8.9 ppb) and that of DDE was 10.8 ppb (1.5-88.1 ppb). There was a positive correlation between DDE and DDT level (r = 0.33, P < 0.01). The serum DDE level was positively correlated with age (r = 0.49, P < 0.01) and DDT x Age (r = 0.62, P < 0.01). No correlation was observed between DDT and age. These results suggest that DDE, a metabolite of DDT, is cumulative in the body. Therefore blood DDE could be used as a cumulative exposure marker for DDT, whereas blood DDT may be used to reflect its recent exposure.

High-performance liquid chromatographic determination of dehydroabietic and abietic acids in traditional Chinese medications

In Asia, there is still a high usage of traditional Chinese medicament by the general population. Some patients with contact dermatitis to these medicaments have been found to be sensitive to colophony on patch testing. Dehydroabietic acid (DHAA) and abietic acid (AA) are the main components of colophony and believed to be the agents responsible for skin sensitization. This paper describes a reliable high-performance liquid-chromatographic method for determining these two resin acids in ointment samples. The samples were either pretreated with diethyl ether or treated with acetonitrile directly by ultrasonication for 30 min. One volume of this sample was added to an equal volume of water and purified by solid-phase extraction. The mobile phase used was methanol-water-phosphoric acid (87:13:0.02, v/v) and the flow-rate was 1 ml/min. DHAA and AA were detected at 4.3 and 6.3 men with ultraviolet detection at wavelength 200 and 239 nm, respectively. However, fluorimetric detection with an excitation wavelength of 225 nm and emission wavelength of 285 nm, provided more selective determination of DHAA. The detection limits for DHAA and AA were 1 ng. Analytical recovery generally exceeded 90%. We analyzed nine types of commonly used topical Chinese medicaments and two types of Western medical ointments in Singapore. The results showed that most of these medicaments contain colophony below 5 ppm (micrograms g-1). Only one Chinese medicament contained > 70 ppm of both allergens and one of the Western medical ointments contained 0.2% of DHAA and 2.2% of AA.

Determination of serum and urinary aluminum by HPLC with fluorometric detection of Al-lumogallion complex

We describe a simple and sensitive HPLC method for quantifying aluminum (Al) in biological fluids by measuring the fluorescence of the Al-lumogallion complex (excitation wavelength 500 nm, emission wavelength 575 nm). Serum samples are deproteinized with 0.83 mol/L perchloric acid and centrifuged; the supernates are mixed with lumogallion reagent. Urine samples are pretreated with sodium hydroxide (2 mol/L) and methanol, kept for 1 h at -20 degrees C, and then centrifuged; the precipitate is resuspended in perchloric acid and mixed with lumogallion reagent, as for serum. The maximal fluorescence complex is formed after 1 h at pH 5 +/- 0.5. The HPLC mobile phase consists of (per liter) 100 mL, of 0.2 mol/L potassium hydrogen phthalate, 220 mL of acetonitrile, and distilled deionized water. The flow rate is 1 mL/min, and the injection volume is 5 microliters. The major aluminum species is eluted at 3.5 min, the lowest detection limit being 0.45 pg. We validated the method with samples collected from normal subjects and from workers occupationally exposed to aluminum. Comparing the results with those by traditional atomic absorption spectrometry of urinary aluminum suggests that the proposed method is reliable.

Determination of serum and urinary aluminum by HPLC with fluorometric detection of Al-lumogallion complex

We describe a simple and sensitive HPLC method for quantifying aluminum (Al) in biological fluids by measuring the fluorescence of the Al-lumogallion complex (excitation wavelength 500 nm, emission wavelength 575 nm). Serum samples are deproteinized with 0.83 mol/L perchloric acid and centrifuged; the supernates are mixed with lumogallion reagent. Urine samples are pretreated with sodium hydroxide (2 mol/L) and methanol, kept for 1 h at -20 degrees C, and then centrifuged; the precipitate is resuspended in perchloric acid and mixed with lumogallion reagent, as for serum. The maximal fluorescence complex is formed after 1 h at pH 5 +/- 0.5. The HPLC mobile phase consists of (per liter) 100 mL, of 0.2 mol/L potassium hydrogen phthalate, 220 mL of acetonitrile, and distilled deionized water. The flow rate is 1 mL/min, and the injection volume is 5 microliters. The major aluminum species is eluted at 3.5 min, the lowest detection limit being 0.45 pg. We validated the method with samples collected from normal subjects and from workers occupationally exposed to aluminum. Comparing the results with those by traditional atomic absorption spectrometry of urinary aluminum suggests that the proposed method is reliable.

Biomarkers of exposure to low concentrations of benzene: a field assessment

OBJECTIVE

To carry out a comprehensive field investigation to evaluate various conventional and recently developed biomarkers for exposure to low concentrations of benzene.

METHODS

Analyses were carried out on environmental air, unmetabolised benzene in blood and urine, urinary trans, transmuconic acid, and three major phenolic metabolites of benzene: phenol, catechol, and hydroquinone. Validations of these biomarkers were performed on 131 never smokers occupationally exposed to the time weighed average benzene concentration of 0.25 ppm (range, 0.01 to 3.5 ppm).

RESULTS

Among the six biomarkers studied, unmetabolised benzene in urine correlated best with environmental benzene concentration (correlation coefficient, r = 0.76), followed by benzene in blood (r = 0.64). When urinary metabolites were compared with environmental benzene, trans, trans-muconic acid showed a close correlation (r = 0.53) followed by hydroquinone (r = 0.44), and to a lesser extent with urinary phenol (r = 0.38). No correlation was found between catechol and environmental benzene concentrations. Although unmetabolised benzene in urine correlates best with benzene exposure, owing to serious technical drawbacks, its use is limited. Among the metabolites, trans, trans-muconic acid seems to be more reliable than other phenolic compounds. Nevertheless, detailed analyses failed to show that it is specific for monitoring benzene exposures below 0.25 ppm.

CONCLUSION

The overall results suggest that most of the currently available biomarkers are unable to provide sufficient specificity for monitoring of low concentrations of benzene exposure. If a lower occupational exposure limit for benzene is to be considered, the reliability of the biomarker and the technical limitations of measurements have to be carefully validated.

Urinary homovanillic acid and vanillylmandelic acid in workers exposed to carbon disulfide

Homovanillic acid (HVA) and vanillylmandelic acid (VMA), two end products of dopamine metabolism, were measured in 60 workers exposed to carbon disulfide (CS(2)) in a rayon factory and in 48 unexposed workers. The airborne CS(2) concentrations in eight major exposure zones of the plant were measured monthly over a period of 4 years, from 1990 to 1994. In addition, the exposure concentrations and exposure history of each worker were integrated to estimate the overall lifetime exposure. Industrial hygiene data showed that the geometric mean concentrations of CS(2) in the plant ranged from 2.68 to 20.19 ppm, and more than 15% of the studied population had been repeatedly exposed to CS(2) at concentrations exceeding the ACGIH recommended time-weighted average of 10 ppm. The results showed that there was a significantly lower level and a higher proportion of CS(2) workers with decreased HVA and VMA excretion. However, there were no statistical correlations between the two dopaminergic metabolites and the mean CS(2) concentration, and years of employment. In contrast, significant dose-effect relationships were observed between these two metabolites and the integrated cumulative exposure (ICE) variable. The correlation coefficients for ICE and HVA, and ICE and VMA were -0.35 (p < 0.01) and -0.20 (p <0.05), respectively. These data suggest that chronic exposure to CS(2) was associated with measurable reduction in catecholamine metabolite concentrations. This finding is compatible with the earlier observations in laboratory animals that CS(2) exposures interfere with neurochemical metabolism.

Evaluation of biomarkers for occupational exposure to benzene

OBJECTIVE

To evaluate the relations between environmental benzene concentrations and various biomarkers of exposure to benzene.

METHODS

Analyses were carried out on environmental air, unmetabolised benzene in urine, trans, trans-muconic acid (ttMA), and three major phenolic metabolites of benzene; catechol, hydroquinone, and phenol, in two field studies on 64 workers exposed to benzene concentrations from 0.12 to 68 ppm, the time weighted average (TWA). Forty nonexposed subjects were also investigated.

RESULTS

Among the five urinary biomarkers studied, ttMA correlated best with environmental benzene concentration (correlation coefficient, r = 0.87). When urinary phenolic metabolites were compared with environmental benzene, hydroquinone correlated best with benzene in air. No correlation was found between unmetabolised benzene in urine and environmental benzene concentrations. The correlation coefficients for environmental benzene and end of shift catechol, hydroquinone, and phenol were 0.30, 0.70, and 0.66, respectively. Detailed analysis, however, suggests that urinary phenol was not a specific biomarker for exposure below 5 ppm. In contrast, ttMA and hydroquinone seemed to be specific and sensitive even at concentrations of below 1 ppm. Although unmetabolised benzene in urine showed good correlation with atmospheric benzene (r = 0.50, P < 0.05), data were insufficient to suggest that it is a useful biomarker for exposure to low concentrations of benzene. The results from the present study also showed that both ttMA and hydroquinone were able to differentiate the background level found in subjects not occupationally exposed and those exposed to less than 1 ppm of benzene. This suggests that these two biomarkers are useful indices for monitoring low concentrations of benzene. Furthermore, these two metabolites are known to be involved in bone marrow leukaemogenesis, their applications in biological monitoring could thus be important in risk assessment.

CONCLUSION

The good correlations between ttMA, hydroquinone, and atmospheric benzene, even at concentrations of less than 1 ppm, suggest that they are sensitive and specific biomarkers for benzene exposure.

Lead-induced nephropathy: relationship between various biological exposure indices and early markers of nephrotoxicity

Lead nephropathy in adults is silent and insidious, characterized by the absence of proteinuria in its early phase. Of the early markers of nephrotoxicity, urinary N-acetyl-beta-D-glucosaminidase (NAG) appears to be the only one that is elevated in early lead nephropathy. However, the elevation in urinary NAG activity may be a response to a sharp increase in renal burden of lead. Its usefulness as a marker of chronic lead nephropathy is thus in doubt. There is a need, then, to identify a reliable early biological indicator of lead-induced kidney damage. Furthermore, there is also a need to identify suitable markers of chronic exposure to describe meaningful dose-response and dose-effect relationships. Traditionally, blood lead (PbB) was used, but the current blood lead level (PbBrec) is more an indicator of recent exposure. Time-integrated blood lead indices (PbBint) derived from repeated serial PbB measurements can be used as indices of chronic exposure. In 128 lead-exposed workers, the PbBint was the most important exposure variable in describing the variability in urinary alpha 1-microglobulin (U alpha 1 m), urinary beta 2-microglobulin (U beta 2m), and urinary retinol binding protein (URBP). U alpha 1m was the only marker that was significantly higher in the exposed group, with a good dose-response and dose-effect relationship with PbBint. The lack of dose-response and dose-effect relationships in other studies may be due to inappropriate exposure markers as well as less sensitive response markers. PbBint has a better correlation than PbBrec. Furthermore, U alpha 1m may be the most sensitive of the markers because of its higher molecular weight.

Glomerular function of lead-exposed workers

Among lead-exposed workers, there is evidence of increased mortality from chronic renal diseases (nephritis and nephrosis). Epidemiological studies using early markers of nephropathy among lead-exposed workers failed to demonstrate early renal changes. This study is aimed at assessing the glomerular function of 137 lead-exposed subjects and at evaluating whether changes in markers of glomerular function are related to exposure indices derived from longitudinal blood lead data. A control group of 153 postal workers was also investigated. Several exposure indices were derived for the exposed workers, including a time-integrated index Pb in blood (PbB)int and the number of times the PbB was above critical values (PbB400, PbB500, PbB600). Through multiple linear regression analysis, PbBint was the best predictor of variation in serum beta 2-microglobulin (S beta 2m) and alpha 1-microglobulin (S alpha 1m) and urinary albumin (UA1b). A small but statistically significant difference in the mean beta 2m was found. S beta 2m was also the only marker showing a significantly higher prevalence rate ratio (PRR) of abnormalities among lead-exposed workers. Though there was no clear dose-response relationship with PbBint as the index of dose, all the 15 subjects with abnormal S beta 2m in the older age group were found in the highest PbBint group. Furthermore, of the 8 subjects with low 4-h creatinine clearance (CrCl4h), 6 had abnormal levels of beta 2m. Two subjects with CrCl4h of less than 75 ml/min/1.74 m2 had high PbBint values, thus suggesting that high blood lead levels over a prolonged time may be associated with decreased CrCl4h. Though the long-term significance of elevated S beta 2m and UA1b is unclear, their association with high PbBint and decreasing CrCl4h indicate a potentially adverse effect. Their relationship with PbB400 and PbB600 suggests that the threshold of 700 micrograms/l for PbB may not prevent the occurrence of lead nephropathy.

Determination of serum aluminium using an ion-pair reversed-phase high-performance liquid chromatographic-fluorimetric system with lumogallion

An ion-pair reversed-phase high-performance liquid chromatographic method with fluorimetric detection, using lumogallion [4-chloro-3-(2,4-dihydroxyphenylazo)-2-hydroxybenzene-1-sulphonic acid] as a ligand, has been successfully applied to the determination of aluminium in human serum. The highly fluorescent aluminium-lumogallion complex (lambda ex 505 nm, lambda em 574 nm) was separated on a LiChrosorb RP-18 column with an eluent consisting of 30% acetonitrile, 70% 0.02 M potassium hydrogen phthalate and 10 microM lumogallion. The proposed system offers a simple, rapid, selective and sensitive method for the determination of aluminium in serum. The detection limit for aluminium was 0.05 microgram/l in aqueous solution and the limit of determination was 2.2 micrograms/l in serum. The recovery of the method is generally over 90%.

Elevated levels of benzene-related compounds in the urine of cigarette smokers

Benzene exposure causes leukemia and lymphomas. Recent epidemiological findings have also shown an association between cigarette smoking and an increased risk of leukemia. However, further evidence is required to document the biological plausibility of this association. In evaluating this link, it is important to note that cigarette smoke contains benzene and various pyrolytic compounds, among other carcinogens. This study aims to determine the uptake of benzene by measuring 3 benzene-related compounds in cigarette smokers and non-smokers. Urinary concentrations of catechol (CAT), hydroquinone (HQ), and trans,trans-muconic acid (tt-MA) were measured by high-performance liquid chromatography (HPLC) with fluorimetric and UV detection, respectively. The results showed that these compounds were present in all urine samples. However, the concentrations were significantly higher in smokers than in non-smokers. The mean level of urinary tt-MA was 0.19 +/- 0.09 mg/g creatinine for 46 male smokers and the corresponding value for 40 non-smokers was 0.14 +/- 0.07 mg/g creatinine. The mean concentrations of HQ and CAT were 0.81 +/- 0.4 and 3.51 +/- 2.6 mg/g creatinine for smokers, and 0.45 +/- 0.4 and 1.94 +/- 1.2 mg/g creatinine for non-smokers, respectively. These results suggest that cigarette smoking is associated with a significant additional exposure to benzene and its related compounds. Furthermore, significant correlations were observed between the concentrations of cotinine, the metabolite of nicotine, and the above compounds. These findings suggest that the exposure originated from cigarette smoking.

Biological monitoring of exposure to low concentrations of styrene

A field study was conducted on 39 male workers exposed to styrene at concentrations below 40 ppm (time weighted average, TWA). Analyses were carried out on environmental air, exhaled air, blood, urine, and two major urinary metabolites of styrene: mandelic acid (MA) and phenylglycoxylic acid (PGA). Head space gas chromatography (GC) with a flame ionization detector (FID) was used for determination of styrene in blood and urine. Postexposure exhaled air was analyzed using capillary GC. Environmental styrene exposure was measured by personal sampling using carbon cloth personal samplers. Urinary metabolites of styrene were determined by high pressure liquid chromatograph (HPLC). When the end-of-shift breath, blood, and urine styrene levels were compared with environmental TWA values, blood styrene correlated best with styrene in air (r = 0.87), followed by breath styrene (r = 0.76). Poor correlation (r = 0.24) was observed between environmental styrene exposure and urine styrene. When styrene metabolites were compared with environmental styrene, the sum of urinary MA and PGA correlated better with styrene in air than MA or PGA alone. The correlations between urinary metabolites and environmental styrene improved when corrected for the specific gravity of urine. Even better correlations were observed when the urinary metabolites were corrected for creatinine. The correlation coefficients for environmental styrene and end-of-shift MA, PGA, and MA+PGA were 0.83, 0.84, and 0.86, respectively. The correlation coefficients between environmental styrene and next morning urinary metabolites fell to 0.47, 0.61, and 0.65 for MA, PGA, and MA+PGA, respectively. These results suggest that determination of the total MA and PGA in urine samples is preferred than separate measurements of MA or PGA. The good correlation between environmental exposure and styrene in the exhaled air also suggests that breath styrene level can be a useful indicator for low level styrene exposure, as the method is specific, noninvasive, and rapid. Urinary styrene seems to be a less reliable indicator for low level styrene exposure.

Kinetics of styrene urinary metabolites: a study in a low-level occupational exposure setting in Singapore

Biological monitoring of styrene exposure commonly involves measurement of styrene metabolites, mainly mandelic acid (MA) and phenylglyoxylic acid (PGA), in the urine of exposed subjects. Previous studies on the kinetics of styrene metabolites in urine were mostly conducted in a controlled environment on subjects exposed to high concentrations of styrene. In this study, we examined subjects exposed to low levels of styrene in a fiber-reinforced plastics (FRP) plant to see whether the excretion kinetics of styrene metabolites are similar under field conditions. Eight healthy Chinese male volunteers were exposed to styrene for 4 h with a mean environmental concentration of 11 ppm. Urine samples were collected continuously for 20 h after termination of the exposure and concentrations of urinary MA and PCA were determined. The results showed that MA was rapidly excreted in urine after the exposure, with a half-life of 2.1 h or 1.9 h when corrected with urine creatinine. The excretion of PGA followed that of MA and the half-life was 8.1 h or 5.1 h after correction with creatinine. The half-lives are considerably shorter compared to those in previous reports, suggesting that environmental factors, exposure conditions, or ethnic differences may affect the excretion kinetics of styrene metabolites. The fast excretion of styrene metabolites is also consistent with the observation that urine MA and PGA levels correlated better with the half-day time-weighted average (TWA) concentration of environmental styrene than with the whole-day TWA concentration. Our findings thus underscore the need for information on excretion kinetics in order to develop an appropriate biological monitoring scheme for specific exposure settings and subjects.

Urinary N-acetyl-beta-D-glucosaminidase activity in workers exposed to inorganic lead

Urinary N-acetyl-beta-D-glucosaminidase (NAG) had been shown to be a useful early marker of renal injury. In workers exposed to lead it seems to be the only early marker but the dose response and dose effect relations are weak. Furthermore, the significance and underlying mechanism of increased urinary NAG activity is far from clear. By studying the isoenzyme profiles of urinary NAG, the significance and underlying mechanism may be further clarified. The heat labile (NAG-A) and heat stable (NAG-B) isoenzyme profiles of 128 workers exposed to lead from a lead stabiliser factory were analysed. NAG activity was expressed as total NAG, NAG-A, and NAG-B activity as well as ratios (NAG-B/total NAG and NAG-B/NAG-A). Exposure indices included the recent concentration of blood lead (BPb), a cumulative blood lead index (TBPb), and the recent change in concentration of blood lead (CBPb). The NAG indices correlated best with CBPb. Nearly 50% of the variation in NAG-B activity could be explained by the combination of all three exposure indices but only the CBPb was highly significant. When these exposure indices were entered separately into the regression equation, CBPb accounted for 36.3% of the variation in NAG-B activity, 5.7% was accounted for by TBPb and 2.7% by BPb. There was also no dose-effect or dose-response relation between the NAG variables and BPb or TBPb groups. With CBPb, there were dose-effect and dose-response relations. With CBPb, there was an increase in NAG variables in the group with more than 25% increase in blood lead over the past six months. The increase in NAG activity in this study is likely to be due to a recent increase in concentration of blood lead and hence presumably a recent rise in renal burden of inorganic lead. This suggests that the increase in urinary NAG activity is a form of acute response to a sharp increase in renal burden of lead, rather than to a cumulative dose. Heat stable NAG is part of the lysosomal membrane and is present in the urine when there is breakdown of lysosomes. Our data therefore contradict suggestions that the increase in urinary NAG activity is due to exocytosis.

Use of inexpensive O antisera as the detecting antibodies for Salmonella antigens in the polymyxin-cloth enzyme immunoassay

The application of O antigen-specific antisera to the detection of Salmonella lipopolysaccharide (LPS) antigens was examined in an enzyme immunoassay using polymyxin-coated polyester cloth. The LPS antigens were extracted with deoxycholate and captured on polymyxin-cloth. A mixture of rabbit antisera to Salmonella O antigens was allowed to react with the captured antigens, and the reacted antibodies were detected by an anti-rabbit IgG-peroxidase conjugate. The assay gave positive results with 40 different Salmonella serotypes which represented more than 99.9% of the serogroups isolated from over 122,000 food, feed and environmental samples analysed at Laboratory Services Division, Agriculture Canada, from 1975 to 1990. Strong cross-reactivity with Staphylococcus aureus was eliminated by pregrowth of the organisms in the presence of sodium deoxycholate. The O antisera were commercially available and are more economical than monoclonal or affinity purified polyclonal antibodies.

Simultaneous determination of hydroquinone, catechol and phenol in urine using high-performance liquid chromatography with fluorimetric detection

A method was developed for simultaneous determination of urinary hydroquinone, catechol and phenol using high-performance liquid chromatography (HPLC) with variable-wavelength fluorimetric detection. Urine samples, after acid hydrolysis, were saturated with sodium sulphate and extracted by diethyl ether. The two buffers used for gradient elution were (A) 10 mM sodium acetate containing 0.5% (v/v) acetic acid and (B) the same as buffer A but containing an additional 20% (v/v) acetonitrile. Hydroquinone, catechol and phenol were separated in a C18 column and detected at 2.9, 6.8 and 13.6 min, respectively. The recovery and reproducibility were generally over 90%. Over 300 extracted samples were analysed and no change in column efficiency was noted. Comparisons were also made with HPLC using ultraviolet (UV) detection and with gas chromatography (GC). The proposed method appears to be more sensitive and reliable than other existing methods. This new method was also validated with urine samples collected from cigarette smokers and from refinery workers exposed to low concentrations of benzene.

Urinary trans,trans-muconic acid determined by liquid chromatography: application in biological monitoring of benzene exposure

We describe a sensitive and specific high-performance liquid-chromatographic method for determining the benzene metabolite, trans,trans-muconic acid (ttMA) in urine by measuring ultraviolet absorbance at 265 nm. We mix 1 mL of urine sample with 2 mL of Tris buffer containing vanillic acid as internal standard (IS) and percolate this through a preconditioned ion-exchange column. After rinsing the column with phosphoric acid solution, acetate buffer, and deionized water, we elute the analytes with 2 mL of an equivolume solution of 1.5 mol/L sodium chloride and methanol. Of this, 5 microL is injected into the HPLC column. The mobile phase used consists of, per liter, 10 mL of acetic acid, 100 mL of methanol, and the rest 5 mmol/L sodium acetate. The flow rate was started at 1 mL/min and increased to 1.5 mL/min after 6 min. ttMA and IS were detected at 5.2 and 10.2 min, respectively. The lowest detection limit is 125 pg. Analytical recovery and reproducibility generally exceeded 90%. We validated the method with urine samples collected from normal persons and from refinery workers exposed to benzene concentrations < 1 microL/L. The results show that urinary ttMA is a promising biological marker for risk assessment of low-concentration benzene exposure.

Concentrations of heavy metals in maternal and umbilical cord blood

Concentrations of lead, cadmium, methylmercury and total mercury were measured in maternal and umbilical cord blood using graphite atomic absorption spectrometry. Two essential metals, copper and zinc, were also determined using ion chromatography. Lead, copper and zinc were found to be lower in the cord blood whereas methylmercury and total mercury were higher in cord blood than in maternal blood. Little differences were noted for cadmium in maternal and cord blood. Significant positive correlations were observed between the concentrations in maternal and cord blood with regard to lead (correlation coefficient, r = 0.44), copper (r = 0.34), zinc (r = 0.29), methylmercury (r = 0.44) and total mercury (r = 0.58). These results suggest that, like essential metals, most heavy metals can move rather freely across the human placenta. The potential health effects of heavy metal transfer from mothers to young infants cannot be discounted.

High-performance liquid chromatographic method for routine determination of vitamins A and E and beta-carotene in plasma

A simple and reliable reversed-phase high-performance liquid chromatographic (HPLC) method for the routine determination of vitamins A and E and beta-carotene in plasma (or serum) with wavelength-programmed ultraviolet-visible absorbance detection is described. A 200-microliters aliquot of serum or plasma sample, after deproteinization with ethanol, and containing tocopherol acetate as internal standard, was extracted with butanol-ethyl acetate. Sodium sulphate was added for dehydration. Analytes of extracted samples were found to be stable for at least four days. A 10-microliters aliquot of this organic extract was used for HPLC analysis. The mobile phase was methanol-butanol-water (89.5:5:5.5, v/v) and the flow-rate was set at 1.5 ml/min. The analytes of interest were well separated from other plasma constituents within 22 min at 45 degrees C. The lowest detection limits of vitamins A and E and beta-carotene were 0.02, 0.5 and 0.1 microgram/ml, respectively. The recovery and reproducibility of the present method were around 90%. The method is sensitive, specific and can be used for epidemiological studies and for routine determination of vitamin deficiency. Several important factors that may affect the analysis are also discussed in this paper.

Separation of globins using free zone capillary electrophoresis

This paper describes the use of high-performance capillary electrophoresis for the separation of globin chains. Adult and newborn haemolysates from normal individuals and children suspected of having thalassaemia were analysed using free zone electrophoresis. Separation of globins was accomplished using a 25 mM phosphate buffer at pH 11.8. Distinct peaks of alpha-, beta- and gamma-chains were resolved within 8 min. The coefficient of variation for within-day and between-day runs was 4.1% and 5.7%, respectively. This method is simple and rapid, and it can be used to screen for thalassaemia and for the clinical study of various haemoglobinopathies.

A study of silica nephrotoxicity in exposed silicotic and non-silicotic workers

The possible human nephrotoxicity of silica has often been suggested by previous anecdotal reports and uncontrolled clinical studies of silicotic patients. Urinary excretions of albumin, alpha-1-microglobulin (AMG), and beta-N-acetyl-glucosaminidase (NAG) were measured in 33 male workers exposed to silica (mean duration of employment 16 years) and 19 male age matched non-exposed subjects with no history of primary or secondary renal diseases. Significantly higher urinary excretions of albumin and AMG were found in the workers exposed to silica. Silicotic subjects (n = 7) also had significantly high excretions of albumin, AMG, and NAG. All but one of the silicotic patients had ceased exposure from three to 17 years before the study. Our findings suggest that prolonged exposure to silica is associated with chronic irreversible nephrotoxicity in exposed workers.

Biological monitoring of occupational exposure to methyl ethyl ketone

This study was conducted to evaluate the usefulness of three commonly used methods of biological monitoring for worker exposed to methyl ethyl ketone (MEK) under field conditions using blood, breath and urine. Environmental MEK exposures were measured by personal sampling with carbon-felt dosimeters. The correlation coefficient (r) between the time-weighted average (TWA) MEK concentration in air and the MEK concentration in blood collected at the end of the work shift was 0.85. The correlation coefficient between the TWA MEK level in air and the concentration exhaled in the breath of workers at the end of the work shift was 0.71. The end-of-shift urinary MEK excretion correlated best with the environmental concentration (r = 0.89). Correlations became lower after urine samples had been corrected for urinary creatinine (r = 0.83) or specific gravity (r = 0.73). After 8 h exposure to 200 ppm MEK, the corresponding end-of-shift urinary excretion was 5.1 mumol/l or 4.11 mg/g creatinine. This value is higher than that previously found in some studies, the difference probably being due to the physical activities of the present workers and their extensive skin contact with the solvent. The kinetics of inhaled MEK was also studied in eight subjects. Breath and urine samples were collected during the 8-h work shift on 2 consecutive Mondays. The results showed that urinary MEK excretion rose steadily until the end of exposure, whereas the MEK concentration in exhaled air varied markedly throughout the day.(ABSTRACT TRUNCATED AT 250 WORDS)

Environmental and biological monitoring of methyl ethyl ketone (MEK)

This study was conducted to evaluate the usefulness of various biological parameters for monitoring of workers exposed to methyl ethyl ketone (MEK). Fifty male workers from a large magnetic videotape factory participated in this study. Personal air samples were collected using 3M organic vapor monitors and analysed for MEK by gas chromatography with flame ionisation detector (FID). 10 mL of urine; blood (1 mL) and exhaled air were also collected at the end of an 8-hour workshift. The headspace GC method was applied for measurement of urinary and blood MEK. MEK in expired air was analysed directly by using a GC/FID.The correlation coefficients (r) between environmental MEK and all other biological parameters measured show significant positive relationships. The r for environmental MEK and urine MEK was 0.84; for blood 0.73 and for breath 0.64. The correlation coefficients between blood and urine was 0.72; blood and breath was 0.88 and urine and breath 0.60. These findings suggest that measurements of unmetabolised MEK in blood, exhaled air and urine can be used for biological monitoring of MEK exposure. Nevertheless, laboratory methodological assessment is in favour of measuring urinary MEK as it is non-invasive and does not have to be analysed immediately after collection.

Male endocrine functions in workers with moderate exposure to lead

Evidence for the effect of occupational exposure to lead on the male endocrine system is conflicting. This study evaluated the primary (testicular) and secondary (hypothalamo pituitary testicular) effects of exposure to lead in 122 current lead workers and 49 non-exposed workers. The mean current blood lead concentration was 35.2 (range 9.6-77.4) micrograms/dl in the exposed workers, and 8.3 (range 2.6-14.8) micrograms/dl in the non-exposed workers. Concentrations of plasma luteinising hormone (LH) and follicle stimulating hormone (FSH) were both significantly higher in the exposed workers, but testosterone (T) was not significantly different between the two groups. In older exposed workers, however (greater than or equal to 40 years), plasma T concentrations were significantly lower, but LH and FSH concentrations were not significantly different. Compared with non-exposed workers, those exposed for less than 10 years had significantly raised LH and FSH and normal T concentrations whereas those exposed for 10 or more years had significantly lower T, and normal LH and FSH concentrations. The concentrations of LH and FSH showed a moderate increase in relation to blood lead concentrations in the range of 10 micrograms/dl to 40 micrograms/dl and thereafter reached a plateau or declined. No apparent trend for plasma T concentrations occurred. No significant difference in prolactin (PRL) concentration was noted. It is concluded that moderate exposure to lead was associated in dose related fashion with small but measurable changes in male endocrine functions that reflected both primary and secondary effects of lead on the testes and the hypothalamo pituitary testicular axis.

Determination of thiamine and its phosphate esters by gradient-elution high-performance liquid chromatography

A high-performance liquid chromatographic method for the determination of thiamine and its phosphate esters using gradient elution is presented. Chromatography was performed on an octadecyl C18 column with post-column derivatization using potassium ferricyanide: thiamine was oxidized to thiochrome, which was detected fluorimetrically. The gradient system avoids the use of a modifier and an ion-pairing reagent. The proposed method enables the separation of thiamine triphosphate, thiamine pyrophosphate, thiamine monophosphate and free thiamine, at concentrations of ca. 2 nM, within 10 min The within-assay precision for blood and serum total thiamine was less than 2 and 5%, respectively, and the between-day variation was less than 3 and 5%, respectively. The method is simple and rapid, and it can be used for screening of thiamine deficiency and for clinical study of various diseases related to vitamin B1 deficiency.

The in vitro and in vivo effects of lead on delta-aminolevulinic acid dehydratase and pyrimidine 5'-nucleotidase

The in vitro and in vivo effects of lead on the activity of pyrimidine-5'-nucleotidase (P5N, E. C. 3.1.3.5) and delta-aminolevulinic acid dehydratase (ALA-D, E.C. 4.2.1.24) were studied. Incubation of blood with lead at concentrations of up to 3 mumol/l (about 60 micrograms/dl) did not appear to affect the activity of P5N, while the activity of ALA-D decreased dose-dependently with lead. Administration of lead caused a marked and rapid suppression of ALA-D in rats. The suppression of lead on P5N appeared to be a rather slow process. The decrease of its activity only came into effect 20 days after administration with lead. these findings suggest that lead induced P5N inhibition is a slow process while the suppression of ALA-D activity occurs much earlier.

Electrothermal atomic absorption spectrometric determination of cadmium and nickel in urine

This paper describes two relatively simple methods for the microdetermination of urinary cadmium (U-Cd) and urinary nickel (U-Ni) using electrothermal atomic absorption spectrometry. Reduction of nonspecific absorption interferences was achieved by temperature programming and background correction using a deuterium arc lamp. Within-run CVs were less than 5% for both U-Cd and U-Ni. Day-to-day variation was less than 8.1% for U-Cd and less than 8.0% for U-Ni. The typical limit for detection was 0.08 micrograms/L for U-Cd and 0.1 micrograms/L for U-Ni. The methods described are useful for mass screening of low level exposure to Cd or Ni.

Renal tubular function of workers exposed to low levels of cadmium

Cadmium induced renal tubular effects were examined in 65 female workers in a factory manufacturing nickel cadmium batteries. Urinary beta 2-microglobulin (beta 2m), urinary N-acetyl-D-glucosaminidase activity (NAG), and serum creatinine and serum urea concentrations were used to assess the renal effects. Of the four measures, only urinary NAG and urinary beta 2m showed a strong positive correlation with blood cadmium concentrations (r = 0.49 and 0.43 respectively); NAG showed a weaker correlation with urinary cadmium concentrations (r = 0.35). Urinary beta 2m has weak correlation with urinary cadmium (r = 0.04). Only urinary NAG showed a significant deterioration in renal function among the exposed group. NAG detects the largest proportion of abnormalities among the exposed group. Abnormal urinary beta 2m is detected in only 15.4% of the workers, half of whom have blood cadmium above 10 micrograms/l. The proportion of abnormalities detected by urinary NAG differs significantly from the proportion of abnormalities detected by urinary beta 2m (p less than 0.01). The age adjusted mean urinary NAG excretion showed a significant rise with urinary cadmium of above 3 micrograms/g creatinine. Urinary beta 2m failed to show any significant rise. With blood cadmium concentrations, the age adjusted mean urinary NAG excretion showed a rise from 1 microgram/l of blood cadmium followed by a plateau between blood cadmium concentrations of 3-10 micrograms/l. No significant rise in mean urinary excretion in beta 2m was seen until blood cadmium concentrations exceeded 10 micrograms/l.

Determination of copper and zinc in serum and whole blood by ion chromatography

An ion chromatography (IC) method for the determination of copper and zinc in serum and whole blood is described. The sample treatment consists of diluting (2:3 for serum and 1:3 for whole blood) with 50% trichloroacetic acid, centrifuging, and dispensing the liquid directly into the chromatograph. The standard additions technique is used to establish the calibration. The close agreement between IC and spectrophotometric data on copper and zinc in serum and whole blood suggests that ion chromatography may be applied to complex biological matrices with minimal sample preparation.

Determination of urinary phenol by acid hydrolysis and capillary gas chromatography

An improved method for the determination of urinary phenol by the traditional precolumn hydrolysis technique is described. Following acid hydrolysis and diethylether extraction, phenol is separated from other urinary components within 3 minutes using the proposed capillary GC method. Analytical recovery was over 95%. The within-run CV was less than 2% and the day-to-day variation was less than 8%.