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Biomedical subjects

G M Marsh

Publications and source records attributed to G M Marsh.

At least 55 records · Page 3Linked to original sources
PubMed1990

Comparison of seven psychometric instruments used for evaluation of treatment effect in Alzheimer's dementia.

Standards of assessment of treatment effect in Alzheimer's disease have been wanting. We report here a comparison of seven methods of assessment of the severity of Alzheimer's disease used in demented subjects (n = 18) and in nondemented controls (n = 18). The instruments tested were the Names Learning test, the Orientation test, the Mini-Mental State Examination, the Alzheimer's Staging Scale (the AZSS), the Global Deterioration Scale, the Clinical Dementia Rating Scale, and the Alzheimer's Deficit Scale (ADS). Two examiners did the testing per telephone methodology, and test/retest design. Results showed all tests to be reliable. A ceiling and/or basement effect was noted in all but the AZSS and the ADS.

Aged↗
PubMed1989

Mortality patterns among workers exposed to acrylamide.

A cohort of 8854 men, 2293 of whom were exposed to acrylamide, was examined from 1925 to 1983 for mortality. This cohort consisted of four plant populations in two countries: the United States and The Netherlands. No statistically significant excess of all-cause or cause-specific mortality was found among acrylamide workers. Analysis by acrylamide exposure levels showed no trend of increased risk of mortality from several cancer sites. These results do not support the hypothesis that acrylamide is a human carcinogen.

Acrylamide↗
PubMed1989

Multistage modeling of lung cancer mortality among arsenic-exposed copper-smelter workers.

Multistage modeling incorporating a time-dependent exposure pattern is applied to lung cancer mortality data obtained from a cohort of 2802 arsenic-exposed copper-smelter workers who worked 1 or more years during the period 1940-1964 at a copper smelter at Tacoma, Washington. The workers were followed for death through 1976. There were 100 deaths due to lung cancer during the follow-up period. Exposures to air arsenic levels measured in micrograms/m3 were estimated from departmental air arsenic and workers urinary arsenic measurements. Relationships of different temporal variables with excess death rates are examined to judge qualitatively the implications of the multistage cancer process. Analysis to date indicates a late stage effect of arsenic although an additional early stage effect cannot be ruled out.

Adult↗
PubMed1988

Direct methods of obtaining information on cigarette smoking in occupational studies.

Many occupational epidemiology studies require complete and accurate information on tobacco use to control for confounding by smoking and to assess interactions of smoking with workplace exposures. This paper reviews and evaluates the availability, reliability, validity, and efficiency of the various data sources and techniques for obtaining individual smoking data, including existing records, biological markers, and surveys. Emphasis is placed on the highly problematic issue of obtaining retrospective smoking histories. In general, the survey technique is currently deemed the most feasible approach for obtaining lifetime smoking histories. Both theoretical and practical aspects of smoking surveys are discussed in detail and are illustrated with a review of the recent literature and with data from two recent retrospective cohort studies conducted at the University of Pittsburgh. Several recommendations involving both the use of smoking data and areas for future methodologic research are presented. These include (1) justification for collecting smoking data in occupational studies based primarily on the potential for smoking to act as an effect modifier rather than solely as a confounder, (2) checks for reliability and validity in all studies which involve the collection of smoking data, (3) more methodologic research to better understand the impact that missing, unreliable, and invalid smoking data may have on the ability to detect and quantify important smoking-exposure interactions, and (4) an assessment of the correlation between biological markers and cigarette carcinogen exposure.

Epidemiologic Methods↗
PubMed1987

A strategy for merging and analyzing work history data in industry-wide occupational epidemiological studies.

Study populations examined in epidemiologic investigations of occupational disease risks often are assembled by the pooling of employee data from several workplaces that share common exposure factors. The primary objectives of this approach are to enhance the representativeness of the overall study population and to obtain sufficient employee sample sizes in exposure subgroups of interest. Among the many epidemiologic aspects that must be considered carefully in such industry-wide studies is the inter- and intra-company or plant comparability of employee work history data. Currently, the literature is void of articles that specifically address the fundamental data reduction and statistical analysis issues related to merging work history data from several distinct cohorts. This paper describes the basic methodologic problems associated with the pooling of work history data and proposes a joint job title/job exposure-based uniform coding scheme (UCS) that facilitates the aggregation of data from similar or diverse cohorts in a variety of epidemiologic study settings. The utility of the UCS as both an efficient data coding structure and a flexible basis for statistical analysis is described within the context of a popular computer software program for analyzing occupational cohort data. The fundamental features of the UCS are illustrated using data from a recent industry-wide study of copper and zinc smelter workers.

Data Collection↗
PubMed1987

Exposure to arsenic and respiratory cancer. A reanalysis.

This paper is a reanalysis of data on the respiratory cancer mortality experience of 2,802 men who worked one year or more during the period 1940-1964 at a copper smelter in Tacoma, Washington. Exposure estimates presented earlier have been recalculated and perhaps improved. While the previous analysis showed only a weak relation between respiratory cancer and arsenic exposure, use of new data shows a much stronger relation--but one that is concave downward and not ordinarily considered for environmental exposure and cancer. This new analysis indicates that arsenic is probably more potent as a carcinogen than indicated by other studies. It also demonstrates the distinction between airborne arsenic and the bioavailability of arsenic, and the importance of this distinction for risk assessment. When a dose-response relation is based on airborne concentrations of arsenic, it is clearly concave downward, but when based on urine concentrations, it appears to be linear.

Arsenic↗
PubMed1987

Some effects of cigarette smoking, arsenic, and SO2 on mortality among US copper smelter workers.

Previous studies of the relationship between arsenic levels and respiratory cancer among copper smelter workers have not directly accounted for possible effects of SO2 exposure and cigarette smoking. This is a report on the 1949-1980 mortality experience of 6,078 white male workers who worked at least 3 years between 1 January 1946 and 31 December 1976 at one or more of eight US copper smelters. The completeness of the cohort was verified statistically, and worker exposures to arsenic, SO2, dust, nickel, cadmium, and lead were estimated from retrospective industrial hygiene surveys reported elsewhere. By using internal controls, a dose-response relationship for lung cancer was observed with exposure to arsenic and SO2. When cigarette smoking data were included with arsenic and SO2 exposure data in a nested case-control analysis, only smoking and arsenic were statistically significant factors. The arsenic-lung cancer relationship was confined to a single smelter associated with high content feed. In the remaining smelters mortality for all causes of death and for all cancer was not high based on comparisons with national, state, and local rates.

Air Pollutants, Occupational↗
PubMed1986

Oral tetrahydroaminoacridine in long-term treatment of senile dementia, Alzheimer type.

We treated 17 patients who had moderate to severe Alzheimer's disease with oral tetrahydroaminoacridine (THA), a centrally active anticholinesterase, in a three-phase study. In the nonblinded first phase of the study, significant improvement occurred in subjects who received the drug, as compared with their pretreatment status, on the global assessment (P = 0.001), the Orientation Test (P = 0.001), and the more sophisticated Names Learning Test (P = 0.001). During the second phase, the subjects served as their own controls in a double-blind, placebo-controlled, cross-over study in which the order of administration of the drug and placebo was randomly assigned. Among the 14 subjects completing Phase II, THA treatment produced significantly better results than placebo on the global assessment (P = 0.003), the Orientation Test (P = 0.004), the Alzheimer's Deficit Scale (P = 0.003), and the Names Learning Test (P = 0.001). Twelve subjects have entered Phase III, which involves long-term administration of oral THA. The average duration of treatment in these subjects at present is 12.6 months; symptomatic improvements have occurred, and no serious side effects attributable to THA have been observed. These encouraging initial results suggest that THA may be at least temporarily useful in the long-term palliative treatment of patients with Alzheimer's disease. We stress that further observations will be required before a clear assessment of the role of this agent can be made.

Administration, Oral↗
PubMed1985

Dietary vitamin A deficiencies and stomach cancer.

The hypothesis of vitamin A intake deficiencies serving as an antecedent factor in the development of stomach cancer was assessed employing a case-control design. Interviews of proxy informants for 111 cases and a pair-matched control group were conducted using a food frequency questionnaire from which an averaged vitamin A intake index was calculated. Stomach cancer cases showed a significantly higher proportion with lowered total vitamin A intake levels (odds ratio = 1.71) which remained constant across sex and socioeconomic status groupings. These results demonstrated a consistency with previous related studies vis-à-vis the strength and specificity of the putative association, a moderate (but statistically nonsignificant) dose-response curve, proper temporal association, and biologic plausibility.

Analysis of Variance↗
PubMed1984

Whole body vibration--a critical review.

Whole body vibration is an environmental stressor to which a substantial portion of the American workforce has been exposed. Numerous experimental studies have examined the acute effects of exposure to WBV but only in the last decade have the chronic effects been addressed. However, to date, no comprehensive review has been conducted of this common occupational exposure. This paper critically reviews the existing literature and summarizes the known health effects. Experimental study results are generally inconsistent and dependent on the characteristics of the vibration exposure. NIOSH's epidemiological studies have shown that several disorders are more prevalent in some occupations; however, causal relationships have not been established. Health professionals should be aware of potential ill effects that may result from exposure to WBV in combination with other environmental stressors.

Automobile Driving↗
PubMed1983

A generalized effective exposure modeling program for assessing dose-response in epidemiologic investigations.

The computer program OCMAP (occupational cohort mortality analysis program) has been extended to allow exposure indices for person-years to be calculated as time-dependent covariates rather than as the usual cumulative indices. The article develops a general formula for weighting exposures and describes the cumulative index, the lag, partial weight, and the lognormal models as specific examples. The implementation in OCMAP is flexible in that it permits these specific models or any other user-specified weighting scheme to be used. Several example schemes are applied to a cohort of workers exposed to arsenic.

Arsenic Poisoning↗
PubMed1983

The general adult inpatient psychiatric assessment scale (GAIPAS).

The General Adult Inpatient Psychiatric Assessment Scale (GAIPAS) is a "here and now" testing instrument based on the general mental status examination. The unique features of the GAIPAS include high interrater reliability with minimal training, "forced choice" format, a scoring method for hostile patients, brief administration time, and a format that lends itself to direct key punch of data. The GAIPAS may be used to follow a symptom, a set of symptoms, or collapsed into a single number comparable to the Global Assessment Scale. Interrater reliability of GAIPAS by interviewer/observer design is given in detail. The GAIPAS is compared to the Brief Psychiatric Rating Scale (BPRS) and Global Assessment Scale (GAS) in the same population for interrater reliability.

Humans↗
PubMed1983

Mortality among workers from a plastics producing plant: a matched case-control study nested in a retrospective cohort study.

Earlier proportional mortality studies of workers in a plastics producing plant in Massachusetts indicated excess mortality from certain digestive and genitourinary cancers. To more definitively examine mortality among these workers a retrospective cohort study was conducted for 2,490 male wage earners who worked at least one year during 1949-1966. Vital status was determined as of Dec. 31, 1976, for 99.7% of the cohort and death certificates were obtained for 98.0% of 603 observed deaths. Comparison with the local county white males revealed a slight excess in digestive system cancer (standard mortality ratio [SMR] = 101.8) and a statistically significant excess (p less than .05) in genitourinary cancer (SMR = 153.6). A relationship was suggested between cancer of the rectum, liver, and pancreas and both the duration and interval from onset of exposure. A secondary matched case-control study was conducted to determine if particular jobs or work areas were related to the excesses found in the primary study. This analysis did not support the hypothesis that digestive or genitourinary cancer was related to a general plant exposure or date of hire. Possible associations warranting continued surveillance were found between rectal cancer and cellulose nitrate production and between prostatic cancer and polystyrene processing. Digestive and genitourinary cancers other than rectal and prostate were not related to employment in any of 21 occupational exposure categories examined.

Adult↗
PubMed1983

Evaluating occupational hazards using information known only to employers: a comparative study.

A comparative study was conducted to assess empirically the suspected bias associated with occupational health studies based only on information obtainable from employers' records. Standardised mortality ratios were extracted from five occupational cohorts for which extensive follow up had been conducted and were compared with proportional mortality ratios based on deaths known (KTE) and unknown (UTE) to the employer, and on total deaths. For the five cohorts examined the suspected bias for the cause of death categories all cancer, respiratory cancer, heart disease, and accidents was generally found to be minimal unless the number of UTE deaths was in excess of 75%. Furthermore, a strong inverse relationship was observed between the percentage of UTE deaths and the level of agreement between proportional mortality ratios based on KTE deaths and total deaths. In partial support of these findings it was also observed that workers who left the industry in three of the five cohorts subsequently experienced similar overall mortality compared with those who continued employment. These findings should serve as a rough indication of the potential value of estimating disease risks from KTE deaths and serve as a guide for other investigators using limited data.

Accidents↗
PubMed1983

Respiratory disease among workers exposed to man-made mineral fibers.

Fibrous glass and mineral wool workers exposed to airborne man-made mineral fibers prior to 1964 were identified and followed for deaths caused by respiratory disease. Fiber exposure levels were estimated for each worker. Average fiber concentrations were very low in relation to a National Institute of Occupational Safety and Health recommendation that exposure to man-made mineral fibers less than 3.5 microns in diameter be limited to 3 fibers per cubic centimeter of air. Fibrous glass workers were exposed to about one hundredth and mineral wool workers to about one tenth of that amount. Respiratory cancer death rates were not excessive for the fibrous glass workers, but they were significantly elevated for the mineral wool workers. When respiratory cancer deaths were compared with fiber exposure levels, however, there was in no instance a strong positive correlation. There was a significant excess in nonmalignant respiratory disease deaths (excluding influenza and pneumonia) for fibrous glass workers and for the total cohort. When these nonmalignant respiratory disease deaths were compared with fiber exposure levels, however, there was in no instance a strong positive association. A special study was made of workers exposed to small diameter fibers. Respiratory cancer deaths were not in excess; however, there was an excess in nonmalignant respiratory disease deaths. This study provided no consistent evidence of a respiratory disease hazard related to exposure to man-made mineral fibers among the workers who produce these fibers. Results must be interpreted in relation to the relatively low exposure levels for these workers.

Adult↗