Biomedical subjects

S J Samuels

Publications and source records attributed to S J Samuels.

At least 19 recordsLinked to original sources

PubMed1992

Urinary mutagenic activity in workers exposed to diesel exhaust.

We measured postshift urinary mutagenicity (mutu; n = 306 samples) on a population of railroad workers (n = 87) with a range of diesel exhaust exposures. Postshift urinary mutagenicity was determined by a sensitive microsuspension procedure using Salmonella strain TA98 +/- S9. Number of cigarettes smoked on the study day and urinary cotinine were highly correlated with postshift urinary mutagenicity. Diesel exhaust exposure was measured over the work shift by constant-flow personal sampling pumps. Respirable particle concentrations were adjusted for the contribution of environmental tobacco smoke, as estimated from nicotine concentration on treated filters. The relative ranking of jobs by this adjusted respirable particle concentration (ARP) was correlated with relative contact the job groups have with operating diesel locomotives. After adjustment for cigarette smoking (active and passive) in multiple regressions, there was no independent association of diesel exhaust exposure, as estimated by ARP, with postshift urinary mutagenicity among smokers or nonsmokers. An important finding is the detection of "baseline" mutagenicity in most of the nonsmoking workers. Despite the use of individual measurements of diesel exhaust exposure, the absence of a significant association in this study may be due to the low levels of diesel exposure, the lack of a specific marker for diesel exhaust exposure, and/or urinary mutagenicity levels from diesel exposure below the limit of sensitivity for the mutagenicity assay.

Adult↗

PubMed1992

Epidemiology of dermatitis among California farm workers.

To estimate the prevalence of dermatitis and risk factors for skin disease in California farm workers, a cross-sectional survey was conducted among grape, citrus, and tomato workers. The prevalence of contact dermatitis was 2% and lichenified hand dermatitis was 13%. Grape workers were more likely to report rashes in the last 12 months than were tomato workers or citrus workers. Grape workers were more likely to have contact dermatitis and lichenified hand dermatitis than were citrus or tomato workers. Increasing hours per week in agriculture, male sex, and not wearing gloves were associated with more lichenified hand dermatitis. We conclude that skin disease in agricultural workers may be causally associated with crop-specific exposures and lack of protective equipment.

Adult↗

PubMed1992

Reduced FVC among California grape workers.

Pulmonary disease due to organic and inorganic dust inhalation represents a significant health problem in the agricultural community. In response to concern over the potential adverse health effects of agricultural exposures, and to address the question of whether the specific crop worked was associated with decreased lung function, we conducted a cross-sectional survey of pulmonary function in a population of 238 grape workers, 355 tomato workers, and 166 citrus workers in California's Central Valley. In addition, 92 workers (66 males and 26 females) performed spirometry before and after an 8-h work shift. Multiple regression analysis of pulmonary function in all 759 workers revealed that age, height, and smoking-adjusted mean preshift FVC was lower in grape workers than in citrus workers in each of three sex and age groups studied: decreased 314 ml for males greater than or equal to 25 yr of age p less than 0.05, 82 ml for males less than 25 yr, and 83 ml for females greater than or equal to 20 yr. Mean adjusted preshift FVC was also lower in grape workers than tomato workers (decreased 249 ml in males greater than or equal to 25 yr [p less than 0.05], 51 ml for males less than 25 yr, and 46 ml for females greater than or equal to 20 yr). Adjusted mean FEV1 was not different by crop, but FEV1/FVC and forced-expiratory flow from 25 to 75% of the FVC (FEF25-75) were significantly elevated in grape workers of the three age and sex groups compared with citrus or tomato workers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Smoking, respiratory symptoms, and pulmonary function among a population of Hispanic farmworkers.

We conducted a cross-sectional study in the agricultural Central Valley to evaluate the prevalence of respiratory symptoms, smoking status, and pulmonary function in Hispanic California farmworkers. Of 759 farmworkers completing questionnaires and spirometry, 747 were Hispanic. The prevalences of current, former, and never smokers (29, 17, and 54 percent, respectively) were comparable to rates in other studies of Hispanics, but daily cigarette consumption (median-five for men and three for women) was lower than in comparison populations. Prevalences of chronic cough, chronic phlegm, and persistent wheeze were low (1.6, 5.1, and 2.8 percent, respectively). Current smoking, increased age, female sex, and working greater than or equal to 8 months per year in agriculture were associated with increased prevalence of respiratory symptoms. Adjusted lung function was higher than for reference populations. Hispanic California farmworkers have a similar smoking prevalence to other Hispanic populations, but lower respiratory symptom prevalences and higher pulmonary function are consistent with lower daily cigarette consumption and the "healthy worker effect."

Adolescent↗

PubMed1992

Creatine kinase and its MB isoenzyme in the third trimester and the peripartum period.

Forty-nine normal pregnant women were recruited late in the third trimester for serial determinations of creatine kinase (CK) and its MB isoenzyme fraction (CK-MB) at four different times: (1) on recruitment between 36 and 40 weeks' gestation, (2) on admission in active labor, (3) immediately after delivery, and (4) on the first postpartum day. In the patients with vaginal delivery (n = 43) total CK was significantly elevated at time 4 compared with times 1, 2 and 3 (P value < .0001). CK-MB fraction was also significantly elevated at time 4 compared with times 1, 2 and 3 (P value < .0001). In 35.7% of the patients at time 4, CK-MB was sufficiently elevated to give the laboratory interpretation of "borderline" or "consistent with a myocardial infarction," even though none of the patients had cardiac symptoms or complications. A review of the literature shows that CK-MB is found not only in myocardium but also in uterus and placenta. The implication of this study is that elevations in total CK and CK-MB should be used with caution during the peripartum period to diagnose myocardial ischemia or infarction.

Adult↗

PubMed1992

Prospective assessment of early fetal loss using an immunoenzymometric screening assay for detection of urinary human chorionic gonadotropin.

OBJECTIVE: To develop an economical, nonradiometric immunoenzymometric assay (IEMA) for the detection of urinary human chorionic gonadotropin (hCG) in studies of early fetal loss. To be effective, the IEMA must have a sensitivity equal to the standard immunoradiometric assay (IRMA) and sufficient specificity to eliminate the need for screening most nonconceptive cycles with the expensive and labor-intensive IRMA. DESIGN: Two different assays were used to measure hCG in daily early morning urine samples from potential conceptive cycles. SETTING: Women undergoing donor artificial insemination (AI) were evaluated in a prospective study. PATIENTS, PARTICIPANTS: Ninety-two women volunteers were selected on the basis of apparent normal reproductive health. INTERVENTIONS: Artificial insemination with nonfrozen donor semen was performed by cervical cup twice each menstrual cycle at 48-hour intervals, and daily urine samples were self-collected throughout the menstrual cycle. MAIN OUTCOME MEASURES: An IEMA was developed to detect urinary hCG using the same antibodies as in the standard IRMA; a study was designed to determine whether this nonradiometric assay could successfully detect the early fetal loss that was detected by the IRMA. RESULTS: Of 224 menstrual cycles analyzed by both assays, a total of six early fetal losses were detected by the IRMA. When the tentative screening rule was set to allow all six of these losses and 95% of future losses to be detected by the IEMA, an additional 34 false-positive results were detected by the IEMA. The specificity of the IEMA with this rule was calculated to be 84%. CONCLUSION: An IEMA based on the same antibodies used for the standard IRMA can serve as an efficient screening assay for the detection of early fetal loss. When the IEMA is used in this manner, nearly 80% of screened menstrual cycles can be eliminated without further testing by the IRMA.

Abortion, Spontaneous↗

PubMed1991

Power and detectable risk of seven tests for standardized mortality ratios.

Power and minimum detectable risk are calculated for seven one-sided tests of standardized mortality ratios with Poisson-distributed events. Each test contrasts the number of observed deaths (D) with the number expected (E). Three tests use exact Poisson probabilities: 1) the exact test, which computes a p value as the probability of equaling or exceeding the number of observed events; 2) the optimal randomized exact test which, although not used in practice, serves as a standard for the other statistics; and 3) the exact "mid-p" procedure, which counts only one-half the probability of the observed event. The remaining four tests use normal approximations to the Poisson ("Z statistics"): 4) Z = magnitude of D-E/square root of E; 5) the Z statistic corrected for continuity, Z = (magnitude of D-E)-0.5)/square root of E; 6) a statistic based on a square root transformation, Z = 2(square root of D-square root of E); and 7) a statistic created by Byar, which, when D is greater than E, is Z = square root of 9D[1-1/(9D)-3 square root of D/E]. Power differences among these procedures with one-sided alpha of 0.05, 0.025, and 0.01 are small as long as four or more events are expected. If fewer than four events are expected, the uncorrected Z has unacceptably high type I error. Simple approximations to the power and detectable risk of these tests are evaluated and prove satisfactory. Differences in minimum detectable risk, actual and approximated, are slight for E of 2.0 or more.

Humans↗

PubMed1991

Semen quality in varicocele patients is characterized by tapered sperm cells.

We used a retrospective case-control study design to compare sperm morphology in 50 varicocele patients and 50 patients with idiopathic infertility. Cases and controls were matched for the percentage of motile sperm and total sperm number per ejaculate. Varicocele patients had significantly more tapered sperm (36% +/- 3% versus 15% +/- 2%) and significantly fewer oval sperm (41% +/- 3% versus 47% +/- 2%). There was no significant difference between cases and controls in any other morphological type.

Case-Control Studies↗

PubMed1991

Design and methods for a survey of lead usage and exposure monitoring in California industry.

A probability sample of California workplaces in 1986 estimated the numbers of workers using lead and their coverage by biological and environmental monitoring. Study steps included (1) identifying 505 stand ard industrial classifications (SICs) with possible lead use; (2) creating an employer lis; (3) identifying for oversampling seven single SICs and a group of 165 SICs with documented high ambient air lead; (4) further stratification by workforce size; (5) prediction from National Institute for Occupational Safety and Health surveys the number of lead-using workers for each employer; (6) drawing facilities into the sample with selection probability proportional to the number of workers predicted to use lead; (7) adjusting the sample selection if an employer listing covered multiple facilities; (8) sending a first-stage telephone/mail questionnaire to identify lead users, who were sent a second questionnaire; (10)follow-up which, aided by statutory authority, resulted in completion rates over 90%; (11) ranking lead-using processes by intensity of exposure; and (12) analysis. Sources of error include random sampling error, misleadingly large standard errors because sampling was with replacement, gaps in the employer list, and inaccurate responses. As a measure for the probability proportional to size sampling, total work force count would have been superior to the predicted number of lead users. Restriction to a single hazard makes a questionnaire-based study feasible, but names of workers, rather than counts, should be requested and a subsample should be visited.

California↗

PubMed1991

Lead use in California industry: its prevalence and health implications.

An estimated 230,000 workers were reported to work in lead-using activities as a result of a 1986 statistical survey of employers in California. However, 68% of these workers worked in activities of relatively low hazard. This included 114,000 workers engaged in electronic soldering. Over 1800 workers were reported to work in battery manufacture, a relatively high-hazard activity, but with consistent monitoring and protection. In contrast, over 4300 workers were involved in radiator repair activities, a high-hazard activity with inconsistent monitoring and protection. Over 8% of construction workers were reported to work in lead-using processes. This sector is exempt from federal Occupational Safety and Health Administration (Fed/OSHA) and California Occupational Safety and Health (Cal/OSHA) lead standards, yet some of the most hazardous activities (welding, grinding, and cutting, etc.) occurred here. Comparison of projections from the National Occupational Hazard Survey of potential lead exposure in California with these survey results suggests consistent and reliable assessment of the major sources of potential occupational exposure to lead.

California↗

PubMed1991

Post-partum anovulation in nursing mothers.

An analysis of breastfeeding and ovulation data from 72 nursing mothers is presented. A proportional hazards model of the data strengthens the hypothesis that a pattern of short, frequent bouts of nursing defines a risk-set of women less susceptible to post-partum ovulation than those who choose to nurse on a schedule of relatively lengthy and infrequent bouts. In contrast, no effect of maternal weight-for-height on the month-specific rate of post-partum ovulation could be detected in the study population comprised of American mothers trained in self-observation of fertility signs.

Anovulation↗

PubMed1991

Reporting of occupational injury and illness in the semiconductor manufacturing industry.

In the United States, occupational illness and injury cases meeting specific reporting criteria are recorded on company Occupational Safety and Health Administration (OSHA) 200 logs; case description data are submitted to participating state agencies for coding and entry in the national Supplementary Data System (SDS). We evaluated completeness of reporting (the percentage of reportable cases that were recorded in the company OSHA 200 log) in the semiconductor manufacturing industry by reviewing company health clinic records for 1984 of 10 manufacturing sites of member companies of a national semiconductor manufacturing industry trade association. Of 416 randomly selected work-related cases, 101 met OSHA reporting criteria. Reporting completeness was 60 percent and was lowest for occupational illnesses (44 percent). Case-description data from 150 reported cases were submitted twice to state coding personnel to evaluate coding reliability. Reliability was high (kappa 0.82-0.93) for "nature," "affected body part," "source," and "type" variables. Coding for the SDS appears reliable; reporting completeness may be improved by use of a stepwise approach by company personnel responsible for reporting decisions.

Accidents, Occupational↗

PubMed1991

The use of a urinary estrone conjugates assay for detection of optimal mating time in the cynomolgus macaque (Macaca fascicularis).

Forty-four female cynomolgus macaques (Macaca fascicularis) were examined to determine the optimum fertile period for mating. Daily urinary estrone conjugates (E1C) were measured, beginning on day 7 of the menstrual cycle, until a 1.5-gold E1C rise above the baseline was detected. The females were bred the next morning. Pregnancies were verified in all animals at day 18 postbreeding, and/or on day 25 postbreeding. Serum progesterone levels were used to correlate the relationship between ovulation and the E1C peak. Forty-four of the 57 cycles indicated a urinary E1C peak between days 10-15 of the menstrual cycle; this peak occurred on the day following the initial 1.5-fold to twofold rise in 90% of the cycles. A single 2-hr mating period the day before, the day of, or the day after the E1C peak resulted in conception in 17 of 44 (38.6%) animals.

Animals↗

PubMed1990

The perinatal impact of cocaine, amphetamine, and opiate use detected by universal intrapartum screening.

Universal urine testing for cocaine, amphetamines, and opiates was performed on 1643 women admitted to an obstetric service for a 1-year period with 20.5% having positive results. There were 299 patients with positive toxicology results matched for race and discharge date with patients having negative toxicology and drug history. Significant differences in age, prior obstetric history, prenatal care, alcohol history, and smoking were noted between groups. There was a significant decrease in birth weight, head circumference, length, and gestational age for the drug-positive group, which was most marked in cocaine and multiple drug users. These differences persisted after we controlled for smoking, prenatal care, and prior preterm births. Differences in birth weight and head circumference remained after we controlled for gestational age. Rates of congenital anomalies and abruptio placental were similar between groups. Perinatal substance abuse is independently associated with growth retardation and prematurity. Multiple risk factors are frequently present, necessitating a comprehensive approach to prenatal care.

Adult↗

PubMed1990

Adverse reproductive outcomes among female veterinarians.

Because female veterinarians are exposed to several known reproductive hazards, the authors conducted a reproductive survey of all female graduates of a US veterinary school (n = 537) and law school (comparison group, n = 794). Analysis was confined to pregnancies completed after the second year of professional school and from 1966 to 1986. Based on one randomly chosen eligible pregnancy per woman (veterinarians, n = 176; lawyers, n = 229), spontaneous abortion rates, adjusted for elective abortions, were 13.3% for the veterinarians and 15.1% for the lawyers; these did not differ significantly. A Cox life table regression model controlling for age, smoking, alcohol use, and prior spontaneous abortion also showed no significant difference in spontaneous abortion rates between the two populations. Using all pregnancies, veterinarians who reported performing five or more radiographic examinations per week had a marginally elevated risk of spontaneous abortion, but the statistical significance disappeared when analysis was limited to one random pregnancy per woman. For one random eligible birth per woman, the mean birth weight did not differ significantly between the veterinarians and lawyers, even after controlling for possible confounders in regression analyses. A higher rate of reportable birth defects was observed among the veterinarians than among the lawyers (relative risk = 4.2, 95% confidence interval 1.2-15.1), but this unexpected result must be considered hypothesis-generating. The authors did not find an overall increased risk for spontaneous abortion or low birth weight infants among veterinarians compared with lawyers, but veterinarians who reported performing five or more radiographic examinations per week may have been at increased risk for spontaneous abortion.

Abortion, Incomplete↗

PubMed1990

Sustained and selective attention in children with learning disabilities.

Sustained and selective attention of 30 fourth-, fifth-, and sixth-grade students with learning disabilities (LD) and 20 controls were compared. A continuous performance test (CPT) yielded no differences for students with LD and controls, suggesting similar ability for both groups in sustaining attention and inhibiting impulsive responding. Subjects with LD made more errors than controls on a selective attention task when letter distractors were adjacent to the target letter but not when they were distant, and more correct responses than controls when facilitating letters were adjacent to the target, suggesting that students with LD are less able to narrow the focus of their attention. Longer response times by students with LD indicate that they have slower information-processing skills than controls. Regrouping students according to teacher ratings for attention deficit-hyperactivity disorder (ADHD) yielded the customary impulsive response set on the CPT and more errors on the selective attention task, but no differences on response times for students with ADHD. LD students with ADHD made more errors than LD students without ADHD when letter distractors were adjacent to the target letter.

Adolescent↗

PubMed1990

Markers of exposure to diesel exhaust in railroad workers.

Diesel exhaust is a known mutagen and a potential human carcinogen. Recent epidemiological studies have demonstrated a small increase in the risk of lung cancer from diesel exhaust exposure. However, many epidemiological studies have used crude estimates of exposure, and even accurate measures of exposure may not be accurate estimates of the internal dose received. Measurement of diesel exhaust exposure also has been limited by the absence of a standard marker. This study was undertaken to evaluate the usefulness of urinary mutagenicity as a biological marker of diesel exhaust exposure in the workplace. We measured the exposure of individual railroad workers to diesel exhaust by using personal air samples taken over two consecutive work shifts. Nicotine in the samples was measured to adjust the respirable particle concentrations for active and passive cigarette smoking. Urine samples were collected at the end of the study work shifts and were analyzed for markers of cigarette smoking (nicotine, cotinine) and for mutagenicity, using a sensitive microsuspension assay (micro preincubation assay; Salmonella strain TA98 with or without S9 enzyme). The number of cigarettes smoked on the study shift was recorded, and subjects completed a questionnaire at the end of the second day on personal habits and exposures at home and work. Multiple regression analyses were used to analyze independent determinants of urinary mutagenicity, including a generalized least-squares analysis that divided residual variation into between- and within-person components. Eighty-seven subjects completed 151 two-day protocols; an additional four subjects provided usable data for a single day (n = 306 samples). Respirable particle concentration was not a good marker of diesel exhaust exposure when contamination by environmental tobacco smoke existed in the work location, but respirable particle concentration that was adjusted for environmental tobacco smoke correlated with a priori assessments of diesel exhaust exposure by job grouping. Phenanthrene concentration, as a potential marker, was measured in a subset of personal samples, and correlated with known diesel exhaust exposure by job grouping. A constant ratio of phenanthrene to respirable particles in area samples from diesel exhaust-exposed work locations suggested that phenanthrene is promising as a marker for diesel exhaust. Mutagenic activity was also measured from extracts of respirable particles in a few personal filter samples, and this technique may be useful for further investigation in epidemiological studies.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants, Occupational↗

PubMed1990

Mechanisms of filtration of morphologically abnormal human sperm by cervical mucus.

It is well known that cervical mucus restricts penetration of morphologically abnormal human sperm, both in vitro and in vivo. However, the mechanisms of such restriction are not well understood. Using videomicrography to simultaneously analyze the motions and morphology of individual human sperm, we analyzed differential penetration of normal and abnormal sperm into fresh human cervical mucus. Abnormal sperm swam slower in mucus than the normal sperm, but their flagellar beat parameters were not commensurately different. Multivariate statistical analysis of the relationship between individual sperm velocity and flagellar beat parameters indicated that the heads of the abnormal sperm experienced greater resistance from the mucus than did normal heads. Differential mucus resistance, more than altered motile vigor, appears to be responsible for the restriction of abnormal sperm during migration through mucus.

Cervix Mucus↗