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Biomedical subjects

J C Robinson

Publications and source records attributed to J C Robinson.

At least 91 records · Page 5Linked to original sources
PubMed1991

Implications of OSHA's reliance on TLVs in developing the air contaminants standard.

This paper evaluates the decision by the Occupational Safety and Health Administration (OSHA) to base its Air Contaminants Standard on the threshold limit values (TLVs) of the American Conference of Governmental Industrial Hygienists. Contrary to the claim made by OSHA in promulgating the standard, the TLV list was not the sole available basis for a generic standard covering toxic air contaminants. The National Institute for Occupational Safety and Health (NIOSH) presented data indicating that the TLVs were insufficiently protective for 98 substances. NIOSH Recommended Exposure Limits (RELs) were available for 59 of these substances. The ratio of PEL to REL ranged up to 1,000, with a median of 2.5 and a mean of 71.4. OSHA excluded 42 substances from the standard altogether despite the availability of NIOSH RELs, solely because no TLV had been established.

Air Pollutants, Occupational↗
PubMed1991

Programmed demethylation in CpG islands during human fetal development.

The mechanism for establishing the DNA methylation patterns observed in adult mammalian tissues is not well understood. To determine when adult patterns are established for housekeeping genes, we examined the clustered CpGs in genes on the human active X chromosome (PGK, G6PD, P3, GdX, HPRT) and the autosomal gene, DHFR. We find unique methylation patterns present at the P3 locus in all tissues analyzed from 6- to 9-week fetal specimens, and at the HPRT locus in adrenal gland DNA at this stage of development. Adult patterns are established subsequently by demethylating specific CpGs. Our results show that demethylating events affecting CpG islands are programmed during mammalian fetal development. They suggest that the process of de novo methylation in the fetus methylates at least some sites in the 3' region of the CpG islands in active genes and that adult patterns are established at 6-14 weeks developmental age by sequence-specific demethylation.

Blotting, Southern↗
PubMed1991

Technological, economic, and political feasibility in OSHA's Air Contaminants Standard.

In 1989, after almost two decades of substance-by-substance standard setting, the Occupational Safety and Health Administration (OSHA) promulgated its Air Contaminants Standard, imposing new exposure limits for 376 toxic substances encountered in U.S. industry. In marked contrast to earlier regulations, the Air Contaminants Standard has generated relatively little industry opposition. This paper analyzes the standard in the context of the twenty-year debate over the appropriate role for technological feasibility and economic compliance costs in occupational health policy. The political feasibility of the new standard is traced to OSHA's abandonment of "technology forcing" in favor of reliance on "off-the-shelf" technologies already in use in major firms. While important as an embodiment of OSHA's new "generic" approach to regulation, the Air Contaminants Standard cannot serve as a model for future occupational health policy, due to its reliance on informal, closed-door mechanisms for establishing regulatory priorities and permissible exposure limits.

Air Pollutants↗
PubMed1991

From health-based to technology-based standards for hazardous air pollutants.

The Clean Air Act Amendments of 1990 represent a major shift in regulatory emphasis for toxic air pollutants. Recognizing the immediate public health benefits that can be gained from the application of currently available and affordable control technologies, Congress has abandoned its insistence that health risks should be the only consideration in establishing emissions standards. Previously excluded concerns about economic costs and technological feasibility will now determine the initial level of pollution control required of toxic air pollution sources. In exchange for reducing the stringency of emissions limits, the newly amended act extends the scope of regulation by listing 189 toxic substances that must be controlled over the next decade. This exchange of regulatory depth for breadth occurs against a history of reluctance by the Environmental Protection Agency to implement the original health-protective language of the Clean Air Act. It mirrors earlier compromises under the Clean Water Act and the Occupational Safety and Health Act.

Air Pollutants↗
PubMed1991

A method for risk-adjusting employer contributions to competing health insurance plans.

Biased selection can threaten the viability of multiple choice health systems unless payments to particular plans are adjusted to offset risk differences among employees. We report the results of a study designed to predict medical care utilization and expenditures for groups of fee-for-service plan (FFS) and health maintenance organization (HMO) enrollees, using characteristics commonly available in the personnel files of large employers. Simulation analyses indicate that the six-equation, maximum likelihood model predicts well for groups of 1,000 or more. Additional data are required to reduce prediction errors for smaller groups. This new methodology potentially allows risk-rating of employer contributions to competing health plans, based on the expected utilization of the individuals choosing each plan.

Economic Competition↗
PubMed1991

Adolescent women's contraceptive decision making.

A modified rational decision model incorporating salient events and social influences (particularly from sexual partners) is used to analyze adolescent women's consistent use of oral contraceptives (OCs) over a six-month period. Data are taken from a panel study of 308 clients of an inner-city family planning clinic. Expected OC use was computed for each subject on the basis of subjective expected utility (SEU) theory, and is found in multivariate analyses to be a significant predictor of actual OC use. In addition, variables representing baseline and follow-up partner influences, the salience of pregnancy for the subject, and positive side effects of OCs during the first months of use are found to predict OC use. Partner's support of OC use during follow-up and positive side effects of OCs are found to predict OC use among subjects for whom OC use was not the expected decision according to baseline SEU. Implications of the findings for models of adolescents' contraceptive behavior and for clinicians are discussed.

Adolescent↗
PubMed1991

Cytochalasin B potentiates epinephrine's outflow facility-increasing effect.

Total outflow facility was determined in both eyes of cynomolgus monkeys by two-level constant pressure perfusion. After a baseline measurement, one eye of the experimental animal received intracameral cytochalasin B (CB); the other eye received vehicle without CB. Twenty minutes later both eyes received intracameral epinephrine (EPI), and 30 min later the outflow facility was again determined. Doses of CB and EPI which were subthreshold when given singly produced significant facility increases when given concurrently. Subthreshold doses of CB given concurrently with a maximal dose of EPI produced significantly larger facility increases than a maximal dose of EPI given alone. A maximal dose of CB produced a larger facility increase than a maximal dose of EPI. Maximal doses of CB and EPI given concurrently produced a larger facility increase than did a maximal dose of EPI alone and had about the same effect as a maximal CB dose given alone. Since CB's facility-increasing effect is likely due to "disruption" of actin filaments in the endothelial cells of the trabecular meshwork and Schlemm's canal and since CB potentiates the facility-increasing effect of EPI, EPI may also act by "disrupting" actin filaments and consequently altering endothelial cell shape.

Actins↗
PubMed1990

Effects and interactions of epinephrine, norepinephrine, timolol, and betaxolol on outflow facility in the cynomolgus monkey.

Total outflow facility was determined in cynomolgus monkeys by two-level constant pressure perfusion. Topical epinephrine increased facility by 30% to 35% three to four hours after dosing, whether given as a single 600-micrograms dose or as twice daily 600-micrograms doses for three days. A single 5.5-micrograms intracameral dose of epinephrine or norepinephrine increased facility by 65% to 70% three to four hours after dosing. A single 180-micrograms topical dose of timolol or betaxolol had no effect on facility three to four hours later. Timolol pretreatment prevented the facility-increasing effect of both topical epinephrine and intracameral norepinephrine, but betaxolol pretreatment prevented neither. These findings indicate that no cumulative facility-increasing effect of epinephrine, beyond the acute (three hour) facility-increasing effect, develops within three days; there may be a facility-decreasing effect of large topical epinephrine doses on the vascular structures external to the trabecular meshwork; there is no, or only subthreshold, facility-affecting ambient beta-adrenergic tone in the meshwork; and the facility-increasing effect of both epinephrine and norepinephrine is mediated by beta 2-adrenergic receptors in the trabecular endothelium.

Administration, Topical↗
PubMed1990

Existence of irritable bowel syndrome supported by factor analysis of symptoms in two community samples.

To determine whether bowel symptoms covary in a pattern consistent with the existence of irritable bowel as a distinct syndrome, bowel symptom questionnaires from 2 independent samples were factor analyzed. Samples consisted of 351 18-40-yr-old women who visited Planned Parenthood clinics for contraception and 149 18-89-yr-old women recruited through church women's societies. Factor analysis of 23 bowel symptoms identified 4 factors (clusters of symptoms that were correlated with each other) in both samples. The factor accounting for the most variance in both samples included relief of pain with defecation, looser stools with pain onset, more frequent stools with pain, and gastrointestinal reactions to eating. This irritable bowel factor was not correlated with an objective measure of lactose intolerance. An independent constipation factor was found in both samples to include self-reported constipation, straining with bowel movements, feeling of incomplete evacuation, and rectal bleeding. Thus factor analysis of bowel symptoms supports the existence of a specific irritable bowel syndrome and suggests symptoms that may be used to diagnose this syndrome.

Adult↗
PubMed1990

Evidence for exacerbation of irritable bowel syndrome during menses.

Many women report that bowel symptoms are associated with menstruation, but neither the prevalence of these complaints nor their physiological basis is known. This study aimed to estimate prevalence, to determine whether patients with irritable bowel syndrome are more likely to make such complaints, and to determine whether bowel complaints during menstruation are attributable to psychological traits such as increased somatization. To estimate prevalence, 369 clients of Planned Parenthood of Maryland were asked whether gas, diarrhea, or constipation occurred during menstruation. These subjects were compared with women referred to a gastroenterology clinic and found to have irritable bowel syndrome or functional bowel disorder (abdominal pain plus altered bowel habits but not satisfying restrictive criteria for irritable bowel syndrome). Thirty-four percent of 233 Planned Parenthood clients who denied symptoms of irritable bowel syndrome or functional bowel disorder reported that menstruation was associated with one or more bowel symptoms. Gastroenterology clinic patients with irritable bowel syndrome were significantly more likely to experience exacerbations of each of these bowel symptoms, but especially increased bowel gas. Self-reports of bowel symptoms during menstruation were not associated with psychological traits or with menses-related changes in affect.

Abdominal Pain↗
PubMed1990

Regulation of occupational carcinogens under OSHA's Air Contaminants Standard.

We compare the information used by the Occupational Safety and Health Administration (OSHA) to regulate carcinogens under its 1989 Air Contaminants Standard to publicly available information on substances with potential carcinogenic activity. Carcinogenicity evaluations were obtained from the National Institute for Occupational Safety and Health (NIOSH), the American Conference of Governmental Industrial Hygienists (ACGIH), the National Toxicology Program (NTP), the Environmental Protection Agency (EPA), and the International Agency for Research on Cancer (IARC). We focus on three sets of substances: those which were regulated as carcinogens by OSHA in the Standard, those which were included in the Standard but whose exposure limits are based on noncarcinogenic effects, and those substances designated as potential carcinogens by NIOSH, ACGIH, and/or NTP but which were excluded from the Standard. The data indicate that OSHA relied almost exclusively upon the recommendations of the nongovernmental ACGIH to the exclusion of IARC and the three governmental bodies. Given their statutory authority to evaluate chemical carcinogenicity for regulatory agencies such as OSHA, the exclusion of NIOSH and NTP is particularly striking.

Air Pollutants, Occupational↗
PubMed1990

Philosophical origins of the social rate of discount in cost-benefit analysis.

The social rate of discount--that is, the way decision makers today evaluate future consequences of collective activity--raises difficult issues of intergenerational justice. When benefits are discounted at the present rate the United States government requires, serious efforts to promote public health over the long term will fail cost-benefit tests. No consensus exists among theorists to establish fair rates; philosophers support discounting with economic arguments that economists reject, while economists no less paradoxically support the concept using philosophical arguments that philosophers disavow. A new emphasis on the role of consumers' and citizens' time preferences, however, will keep open rather than close debates on the social discount rate.

Consumer Advocacy↗
PubMed1989

An evaluation of Medicaid selective contracting in California.

This study used 1982-1986 data on 262 private community hospitals to evaluate the effects of selective contracting for inpatient services by California's Medicaid program. Selective contracting by Medicaid significantly reduced the rate of inflation in average costs per admission and per patient day, while slightly increasing average lengths of patient stays. Private sector contracting also reduced cost inflation rates significantly and caused small, non-significant, reductions in lengths of stays. Hospital savings in 1986 due to Medicaid selective contracting were $836 million, 7.6% of what hospital expenditures would have been in the absence of contracting.

California↗
PubMed1989

Exposure to occupational hazards among Hispanics, blacks and non-Hispanic whites in California.

Relative risks of exposure to each of six types of occupational injuries and illnesses for Hispanic and Black workers compared to Whites who are not Hispanic were calculated using 1986 California data. Among males, Hispanics faced relative risks of exposure to all hazards adjusted for education and years of work experience of 1.33 (95% CI 1.22, 1.45), while Blacks faced relative risks of 1.17 (1.0, 1.37). Among females, adjusted relative risks were 1.19 (1.09, 1.29) for Hispanics and 1.31 (1.15, 1.50) for Blacks.

Accidents, Occupational↗
PubMed1989

Business-cycle influences on work-related disability in construction and manufacturing.

Business-cycle upswings generate increased hiring of inexperienced workers and speedups in production methods. The upswings, however, are also associated with sharp increases in disabling work-related injury rates. Data from California for the years from 1953 to 1985 demonstrate the cyclical sensitivity of five types of disabling occupational injuries, fatalities, and acute occupational illnesses to cyclical economic fluctuations. Public policy toward work-related disability needs to focus on macroeconomic determinants of employment and unemployment patterns, as well as on improved safety training programs and worker participation in shop-floor decision making.

Accidents, Occupational↗
PubMed1989

Effects of vagal cryo-interruption on colon contractions in monkeys.

The influence of the vagus nerve on normal colon contractions, and the distal extent of this influence along the colon, is unknown. It is generally thought that the vagus nerve has little, if any, influence on normal colon contractions, and if there is any effect, it is limited to the proximal colon. The technique of reversible truncal vagotomy by cooling (vagal cryo-interruption) was used to explore the influence, and extent of any influence, of the vagus nerve on contractions of the colon in unanesthetized monkeys. Each monkey was subjected to vagal cryo-interruption in the fasted and fed states. In both states this caused a significant decrease in contractions in the proximal, middle, and distal portions of the colon, compared with baseline control and recovery periods. These studies indicate that the vagus nerve plays a role in normal contractions of the intra-abdominal colon in both the fasted and the fed states and that it also plays a role in the gastrocolic response.

Animals↗