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Biomedical subjects

C E Becker

Publications and source records attributed to C E Becker.

At least 37 records · Page 2Linked to original sources
PubMed1990

Micronucleated erythrocytes as an index of cytogenetic damage in humans: demographic and dietary factors associated with micronucleated erythrocytes in splenectomized subjects.

Erythrocytes containing micronuclei serve as an indicator of genotoxic exposure in splenectomized individuals. Micronucleated erythrocytes, derived from cytogenetically damaged RBC precursors, are not selectively removed from peripheral blood in individuals who lack splenic function. The relationship between micronucleated cell frequencies and demographic, environmental, and dietary factors was examined in 44 subjects with previous splenectomy due to trauma. Their micronucleated cell counts fit a log-normal distribution, with geometric means of 3.3 micronucleus-containing cells/1000 reticulocytes and 2.7/1000 normochromatic erythrocytes. A multiple regression analysis showed that drinking five cups of coffee or tea/day (relative to none) was associated with an approximately 2-fold higher frequency of micronucleated cells. Weaker statistical associations were also noted with micronucleus frequency and the consumption of calcium supplements (associated with a higher frequency) and vitamins A, C, or E (lower frequency). An apparent trend of higher micronucleus counts with age was attenuated when other factors were considered in the regression. Cigarette smoking and decaffeinated coffee consumption were among the factors not associated with elevated micronucleated cell frequencies. Because the occurrence of micronuclei in reticulocytes reflects cytotoxic exposures within the past 3-8 days, it may be possible to test directly the relationship of these factors to micronucleus formation through intervention studies.

Chromosome Aberrations↗
PubMed1990

Influence of race, tobacco use, and caffeine use on the relation between blood pressure and blood lead concentration.

A number of studies have suggested a small to moderate positive relation between blood pressure and blood lead concentration in males (2-4 mmHg/In(microgram/dl]. However, this 1986 study of San Francisco bus drivers suggests larger relations in black males (n = 132) for both systolic pressure (7.5 mmHg/In(microgram/dl] and diastolic pressure (4.7 mmHg/In(microgram/dl] at very low blood lead concentrations (2-21 micrograms/dl). This increase appears to result from negative confounding, particularly after taking into account tobacco use. Relations are even larger in blacks who infrequently use caffeine (16.7 and 10.4 mmHg/In(microgram/dl) for systolic and diastolic pressure, respectively). In contrast, a negative relation between systolic pressure and blood lead concentration (-5.7 mmHg/In(microgram/dl] is suggested in nonblack males (n = 117). These findings indicate that race, lead accumulation, and physiologic effects related to caffeine use (e.g., catecholamine effects) may interact to produce marked differences in effect on blood pressure.

Black or African American↗
PubMed1990

Neurotoxicological evaluation of hospital sterilizer workers exposed to ethylene oxide.

Ethylene oxide is now frequently used to chemically sterilize heat-sensitive materials in the hospital setting. Previous reports of neurotoxic effects of ethylene oxide have been described in animals and humans. Recent reports suggest that cognitive deficits may be associated with chronic low-level ethylene oxide exposure. We undertook this study of hospital workers with chronic ethylene oxide exposure and compared them with a non-exposed control group in an attempt to detect neurological and neuropsychological abnormalities. Ethylene oxide breathing zone levels of up to 250 ppm in exposed subjects were reported. All evaluations were done without examiners' knowledge of exposure status of the subjects. The exposed group was found to have a statistically significant lower P300 amplitude, bilaterally hypoactive distal deep tendon reflexes and poorer performance on neuropsychological tests involving psychomotor speed. Exposed subjects acknowledged more symptoms and higher levels of depression and anxiety. Nerve conduction velocities and EEG spectral analysis were similar in both exposed and control groups as were scores on most psychological tests. Based upon this information and prior reports, ethylene oxide should be considered in a differential diagnosis of neuropsychological, peripheral and central nervous system dysfunction in workplace settings associated with ethylene oxide exposure.

Adult↗
PubMed1990

Neuropsychologic "impairment" in a cohort of hospital workers chronically exposed to ethylene oxide.

Ethylene Oxide is widely used to sterilize heat-sensitive materials. Acute and chronic neurogenic effects to the central and peripheral nervous system in man and animals have been described. To assess the chronic, subtle neuropsychologic effects of ethylene oxide, we performed a cross-sectional study of 25 hospital central supply workers exposed to low levels of ethylene oxide and 24 unexposed control workers. Subjects were tested using a neuropsychological screening battery by examiners blinded to exposure status. Testing results were reviewed independently by two neuropsychologists without knowledge of exposure. Subject status was categorized as normal, "impaired," or disagreement (between the two neuropsychologists). There were significantly more subjects concordantly judged as impaired in the exposed group versus the control group (chi 2 (2) = 6.0861, p less than 0.05). Although limited by the cross-sectional study design and the global categorization, these findings suggest that CNS dysfunction and cognitive impairment may result from chronic ethylene oxide exposure in hospital central supply units.

Adult↗
PubMed1990

Chemical dependency and drug testing in the workplace.

Urine testing for drug use in the workplace is now widespread, with the prevalence of positive drug tests in the work force being 0% to 15%. The prevalence of marijuana use is highest, and this can be reliably tested. Though it is prudent to rid the workplace of drug use, there is little scientific study on the relationship of drug use and workplace outcomes, such as productivity and safety. Probable-cause testing and preemployment testing are the most common applications. Random testing has been less accepted owing to its higher costs, unresolved legal issues, and predictably poor test reliability. Legal issues have focused on the right to policy, discrimination, and the lack of due process. The legal cornerstone of a good program is a policy that is planned and agreed on by both labor and management, which serves both as a contract and as a procedure in which expectations and consequences are known. The National Institute on Drug Abuse is certifying laboratories doing employee drug testing. Testing methods when done correctly are less prone to error than in the past, but screening tests can be defeated by adulterants. Although the incidence of false-positive results is low, such tests are less reliable when the prevalence of drug abuse is also low.

Civil Rights↗
PubMed1990

Comparison of the NES and CNS/B neuropsychological screening batteries.

Computer and hand administered neuropsychological tests are utilized in the evaluation of central nervous system changes associated with environmental or occupational exposure to neurotoxicants. This study compares the computerized Neurobehavioral Evaluation System (NES) developed by Baker et al., 1985, with the hand administered California Neuropsychological Screening Battery (CNS/B) developed by Bowler et al., 1986. Both batteries were designed for screening of the effects of neurotoxicants on the central nervous system and require less than one hr to administer. Both screening batteries consist of tests of: mood, word knowledge, attention, concentration, learning and memory and psychomotor and visuomotor and visuospatial abilities. They were administered in a standardized fashion to 106 subjects. Results indicate strong positive correlations for tests of word knowledge, moderate correlations for attention and concentration, while weaker correlations were obtained for tests of memory, psychomotor and visuomotor and visuospatial ability. The NES may be more useful for large epidemiological studies while the CNS/B appears more useful for individual screening and clinical studies.

Anxiety Disorders↗
PubMed1989

Occupational infection with human immunodeficiency virus (HIV). Risks and risk reduction.

As the epidemic of the acquired immunodeficiency syndrome (AIDS) expands, the prevalence of the human immunodeficiency virus (HIV) infection in health care environments will increase and health care workers in many locations are likely to be at increased risk for exposure. The Fifth Annual Advances in Occupational Cancer Conference, held in December 1988 in San Francisco, addressed occupational HIV infection. Symposium participants concluded that the risk of HIV infection for health care workers is low but not zero. Implementation of universal blood and body fluid precautions was agreed to as an appropriate method of preventing exposure to HIV, especially for preventing needlestick accidents. Current standards for hospital waste disposal were judged to be adequate to prevent transmission of HIV, and confidential testing for HIV antibody in health care workers with follow-up counseling was recommended where indicated. It was also agreed that the risk of occupational exposure to HIV does not free health care workers from the responsibility to provide care to infected persons.

AIDS Serodiagnosis↗
PubMed1989

Cross-sectional neurotoxicology study of lead-exposed cohort.

Although the toxic effects of lead have been known for centuries, lead intoxication is still widespread in the United States. Without baseline tests of neuropsychological, neurobehavioral and neurophysiological testing it may be difficult to detect subtle changes in neurological function after lead exposure. This may be further confounded by partial chelation treatment and exposure to neurotoxic mixtures or inability to quantitate alcohol consumption. We undertook a cross-sectional study to address these problems in 24 exposed and 29 control subjects in a plant that manufactured electrical components using fritted leaded glass to coat capacitors and transistors. Potentially exposed workers had blood lead levels ranging between 3 micrograms/dL to 135 micrograms/dL. Industrial hygiene monitoring revealed the plant's air lead levels ranged from 61 micrograms/m3 to 1,700 micrograms/m3 in excess of OSHA permissible exposure limits of 40 micrograms/m3/10 hr day. Using a specially designed battery of neurophysiological, neurobehavioral and neuropsychological screening tests, we demonstrated a significant difference from controls in measures of psychomotor speed, motor strength and verbal memory. Although limited by the cross-sectional design, these findings support the hypothesis that the battery of neurophysiological, neuropsychological and neurobehavioral tests can detect a significant inter-group differences between lead-exposed and control subjects.

Adult↗
PubMed1989

How an occupational medicine physician views current blood-borne disease risks in health-care workers.

Estimating the risks of blood-borne diseases to health care workers is an important area of concern for occupational health physicians. It is best now to view this risk as an occupational injury that can be prevented. The specific numbers estimating risks are rarely as important to the worker as are methods that are available to reduce or eliminate this risk. By placing the risk of blood-borne diseases in perspective with other injuries, it can be appreciated from this information that the estimates of occupational risks of blood-borne diseases to health care workers is extremely variable, but will never be zero. The single most important variable that is preventable is exposure. Major research and educational methods are needed to continue to explore all avenues leading to exposure reduction in the health care setting.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Blood pressure and blood lead concentration in bus drivers.

San Francisco bus drivers have an increased prevalence of hypertension. This study examined relationships between blood lead concentration and blood pressure in 342 drivers. The analysis reported in this study was limited to subjects not on treatment for hypertension (n = 288). Systolic and diastolic pressures varied from 102 to 173 mm Hg and from 61 to 105 mm Hg, respectively. The blood lead concentration varied from 2 to 15 micrograms/dL. The relationship between blood pressure and the logarithm of blood lead concentration was examined using multiple regression analysis. Covariates included age, body mass index, sex, race, and caffeine intake. The largest regression coefficient relating systolic blood pressure and blood lead concentration was 1.8 mm Hg/ln (micrograms/dL) [90% C. I., -1.6, 5.3]. The coefficient for diastolic blood pressure was 2.5 mm Hg/ln (micrograms/dL) [90% C. I., 0.1, 4.9]. These findings suggest effects of lead exposure at lower blood lead concentrations than those concentrations that have previously been linked with increases in blood pressure.

Adult↗
PubMed1988

Environmental lead exposure and the kidney.

Lead and its components remain widely distributed in the environment and in some workplaces. Lead serves no useful physiological function, yet is potentially toxic to several organ systems. For many years human health effects have been recognized after heavy lead exposure. Recently more subtle human effects have been suggested invoking nervous system, reproductive and kidney function. Assessing lead body burden and dose-response relationships of this metal by blood lead determination, porphyrin assessments, chelation testing or bone lead studies may be difficult. Quantitative assessment of subtle changes in kidney function by routine BUN, creatinine, or urinalysis also poses problems. There is now mounting evidence that chronic low level environmental lead exposure may subtly effect kidney function. This paper first examines the history of lead and kidney function and then examines critically the evidence associating low-level environmental lead exposure and effects on renal function.

Animals↗
PubMed1987

The effects of differential induction of cytochrome P-450, carboxylesterase and glutathione S-transferase activities on malathion toxicity in mice.

The organophosphorous pesticide malathion is metabolized by three hepatic enzyme systems: the microsomal cytochrome P-450-dependent monooxygenase system, the microsomal carboxylesterases, and the cytosolic glutathione S-transferases. We produced differential induction of these three enzyme systems in mice with phenobarbital and 2(3)-tert-butyl-4-hydroxyanisole (BHA) and examined the effects of the induction on the inhibition of acetylcholinesterases by malathion. Phenobarbital not only significantly induced hepatic microsomal cytochrome P-450 (p less than 0.05) but also increased microsomal carboxylesterase activity (p less than 0.05). BHA not only increased the activity of microsomal carboxylesterases (p less than 0.05) but also substantially increased cytosolic glutathione S-transferase activity (p less than 0.05). Despite the differential effects of phenobarbital and BHA on the three enzyme systems, neither agent protected the mice against malathion toxicity.

Animals↗
PubMed1987

Evidence of neurologic dysfunction related to long-term ethylene oxide exposure.

Eight hospital workers with chronic ethylene oxide exposure were age-sex matched with eight nonexposed controls with no significant differences in educational backgrounds and vocabulary scores. The exposed group performed more poorly on all eight measures of cognition, memory, attention, and coordination, with 71.3% less accuracy on the Hand-Eye Coordination Test. There was a dose-response relationship between exposure and the following: Continuous Performance Test and sural velocity. These findings suggest that neurologic dysfunction may result from long-term low-dose exposure to ethylene oxide, and that these effects may occur at exposure levels common in hospital sterilizer operations.

Adult↗
PubMed1986

Pharmacokinetics of CaNa2EDTA and chelation of lead in renal failure.

The pharmacokinetics of 1 gm intramuscular doses of CaNa2 (14C-)EDTA and the chelation of lead (Pb) were studied in 10 subjects with varying degrees of renal function and normal body burdens of Pb. The clearance of CaNa2EDTA significantly correlated with creatinine clearances (CLCR) (r = 0.8373; P = 0.0097). Clearances were decreased in subjects with CLCR less than 70 ml/min as compared with subjects with CLCR greater than 100 ml/min (28 vs. 76 ml/min). Maximum serum CaNa2EDTA concentrations and volume of distribution (Varea) (0.05 to 0.23 L/kg) were similar in all subjects. The Varea is smaller than previously described and is more consistent with other experimental data. Considering all subjects, initial blood Pb concentrations correlated with cumulative urine Pb excretion over 3 days (r = 0.8967; P = 0.0005). Urine Pb excretion did not correlate with measures of renal function or measures of CaNa2EDTA kinetics. Subjects with abnormal CLCR showed significantly greater decreases in blood Pb from day 1 to day 4 (7.0 micrograms/dl vs. 1.2 micrograms/dl) compared with normal subjects. These decreases in blood Pb correlated with CLCR (r = 0.7774; P = 0.138) and urine protein (r = 0.8435; P = 0.0087) but not with urine Pb excretion. Renal dysfunction may alter Pb chelatability, bone-blood Pb reequilibration, PbEDTA distribution, or PbEDTA excretion.

Adolescent↗
PubMed1986

Serum formate concentrations in methanol intoxication as a criterion for hemodialysis.

To evaluate the utility of serum formate concentrations, four patients were studied after ingestion of a methanolic copying fluid. All patients were initially intoxicated. Twelve to twenty-four hours later, signs and symptoms included nausea, abdominal pain, hypokalemia, acidosis (three patients), and pathologic ocular findings (two patients). All patients were treated with ethanol and folate. The two patients with ocular signs and acidosis had high serum formate concentrations (75 and 55 mg/dL, respectively). One of the two patients had a high methanol concentration (222 mg/dL) and required hemodialysis; the other patient did not (methanol concentration, 24 mg/dL). In the other two patients without ocular signs, initial formate concentrations were undetectable (limit of detection, 0.5 mg/dL); however, one patient required hemodialysis because the methanol concentration was 72 mg/dL. Formate is the mediator of ocular injury and acidosis. In these patients formate concentrations correlated with the clinical condition but methanol concentrations did not.

Acidosis↗