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Biomedical subjects

V A Clark

Publications and source records attributed to V A Clark.

At least 55 records · Page 3Linked to original sources
PubMed1984

Zinc supplementation during pregnancy: effects on selected blood constituents and on progress and outcome of pregnancy in low-income women of Mexican descent.

The effects of zinc supplementation on levels of various blood constituents and the outcome of pregnancy in 213 Hispanic women attending a prenatal clinic in Los Angeles was assessed in this double-blind study. The women were randomized into either a control (C) or a zinc-supplemented (Z) group and received similar vitamin and mineral supplements except that 20 mg zinc was added to the Z group's capsules. At the final interview, women (C + Z) with low serum Zn levels (less than or equal to 53 micrograms/dl) had higher (p less than 0.01) mean ribonuclease activity and lower (p less than 0.01) mean delta-aminolevulinic acid dehydratase activity than women with acceptable serum zinc levels. The incidence of pregnancy-induced hypertension was higher (p less than 0.003) in the C than in the Z group, but pregnancy-induced hypertension was not associated with low serum zinc levels at either the initial or final interview. The expected increase in serum copper levels was greater (less than 0.001) in women with pregnancy-induced hypertension (C + Z) than in normotensives. Except for pregnancy-induced hypertension, there was a higher incidence of abnormal outcomes of pregnancy in the noncompliers than in the compliers (C + Z).

California↗
PubMed1984

Application of simulation techniques for estimating duration of multiple sclerosis derived from prevalence-formed cohorts.

Comparisons of the average duration of multiple sclerosis derived from a prevalence survey of cases alive in 1970 in a low-risk area (Los Angeles County, California) and a high-risk area (King and Pierce Counties, Washington) suggest that patients in the high-risk area had a longer duration of disease than patients in the low-risk area. Because this finding was unexpected and because the underlying population of these two areas has been increasing at different rates, two simulation models were developed to estimate the duration of multiple sclerosis from a prevalence survey, taking into account the effects of changes in the population over time. Comparison of the durations derived from the two simulation studies suggested that underestimation of true backward recurrence time from the simulation studies was similar for the two study areas. Thus, the observed differences in duration between the two areas probably reflect the course of disease rather than differences in rate of growth of the two populations. These studies demonstrate the usefulness of simulation studies in estimating disease duration from cohorts derived from prevalence surveys of non-stable populations.

Adult↗
PubMed1984

Onset symptoms as predictors of mortality and disability in multiple sclerosis.

941 cases of definite/probable multiple sclerosis living in Los Angeles County, California and King and Pierce Counties, Washington in 1970 who had onset between 1960 and 1969 were followed for mortality and disability through 1980. Early age of onset and residence in Washington State were predictors of less rapid and severe subsequent course. Coordination symptoms at onset were prognostic of rapid progression to disability and/or early death, whereas early motor weakness was significantly predictive only for disability. The presence of sensory symptoms in addition to motor and/or coordination symptoms at onset, however, indicated a better prognosis than coordination and/or motor symptoms alone. This observation and the results of regression analyses indicated that specific groupings of symptoms at onset were more important for predicting course than the number of symptoms present at onset.

Adult↗
PubMed1984

The UCLA population studies of chronic obstructive respiratory disease. VII. Relationship between parental smoking and children's lung function.

Results of previous studies of the impact of parents' smoking on children's lung function have been conflicting. To evaluate further the effect of passive smoking on the lung function of children, we analyzed respiratory questionnaire and lung function results obtained during field testing of residents (aggregated according to household) of 4 census tracts in the Los Angeles area. We report here on 971 white, non-Hispanic, nonsmoking, nonasthmatic children residing in households in which the smoking status of both parents was known; households with ex-smoking parents were excluded from analysis. We divided these children into 3 categories related to parental smoking status: (1) at least mother smokes , (2) only father smokes , and (3) neither parent smokes . Prediction equations for several indexes of forced expired volume and flow were derived separately for boys and girls 7 to 17 yr of age. Analysis of variance was used to compare lung function residuals of children in the 3 different passive smoking categories. Analysis was performed separately on younger (7 to 11 yr of age) and older (12 to 17 yr of age) children of each sex. Among younger male children, residual values were significantly lower in the maternal smoking category than in the other 2 household categories for maximal flow and maximal flow after exhalation of 25% of forced vital capacity (FVC) (p less than or equal to 0.05); no differences were noted between the paternal-smoking only and nonsmoking household categories. A trend toward similar results was found in older male children, which approached significance (p less than 0.1). Among females, forced expiratory flow during the middle half of the FVC and maximal flow after exhalation of 75% of FVC were significantly lower in relation to maternal smoking in the older children only (p less than or equal to 0.05). ANOVA revealed no decrement in lung function in relation to passive smoking among children with asthma or bronchitis (n=138).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

The UCLA population studies of chronic obstructive respiratory disease. VIII. Effects of smoking cessation on lung function: a prospective study of a free-living population.

We evaluated effects of smoking cessation on lung function and respiratory symptoms of residents 25 to 64 yr of age from 3 communities in the Los Angeles area who completed a detailed respiratory questionnaire and measurements of forced expired volumes and flow rates, closing volume, and closing capacity at 2 times (T1 and T2) 5 yr apart. Results were analyzed in 2,401 participants who fit into 4 smoking categories: never smokers (414 males, 737 females); former smokers (294 males; 172 females); quitters between T1 and T2 (106 males, 62 females); and continuing smokers (278 males, 338 females). Covariance analysis was used to determine differences in lung function across smoking categories at T1 and T2 (adjusted for T1 values) and differences in decline in lung function between T1 and T2. Chi-square analysis was used to compare continuing smokers and quitters with respect to changes in respiratory symptoms. In this population, smoking at T1 was associated with impairment in all indexes of lung function evaluated. Smoking cessation led to significant improvement in symptoms of cough, wheeze, and phlegm production, and to significantly less decline in indexes of small airway function during 5 yr compared with measurements in continuing smokers. However, at T2, lung function still was lower among quitters compared with former and never smokers. Forced expiratory volume in one second (FEV1) was marginally improved in women who quit compared with those who continued to smoke.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Underlying cause of death as recorded for multiple sclerosis patients: associated factors.

The coding of multiple sclerosis (MS) as underlying cause of death (UCD) on the death certificate provides an important epidemiologic resource for both descriptive and analytic studies. However, not all deaths among MS patients will be so coded. We investigated the effect on estimated occurrence of MS and on characteristics of MS patients when only UCD codes are used to identify cases. Of 2329 MS patients living in Los Angeles County (California) or King/Pierce Counties (Washington) in 1970, 438 had died by 1980. Only 53% of the deaths were coded to MS; 47% were attributed to other causes. Based on our comparisons, the use of only MS-coded deaths to describe decedents would: underestimate the age at MS onset; overestimate the female:male ratio; underestimate age at death; and underestimate duration of MS. Also, the percentage of MS-coded deaths decreased with lengthening duration of follow-up of these prevalent cases. The effect of using only UCD codes to report characteristics of decedents with other chronic diseases may well be similar.

Adult↗
PubMed1983

Race, ethnicity, and depression: a confirmatory analysis.

This study addresses two questions: (a) Are depressive-symptom scales equally indicative of depression in different racial/ethnic groups and (b) are there mean differences between the groups in the underlying depressive disorder assessed by these scales? The data consist of interviews obtained from a large community survey of depression in Los Angeles County. Four racial/ethnic groups were considered: Anglos, blacks, English-speaking Hispanics, and Spanish-speaking Hispanics. Confirmatory factor analysis was used to test both one-factor and two-factor models of depression. An invariant factor pattern was demonstrated. No significant mean differences on a factor of Depression were found, but the groups were found to differ on a Well-Being factor. Implications for survey research on psychiatric impairment among different racial/ethnic groups are discussed.

Black or African American↗
PubMed1983

Zinc supplementation during pregnancy: zinc concentration of serum and hair from low-income women of Mexican descent.

The effect of zinc supplementation on concentrations of zinc in hair and serum of 213 pregnant Hispanic women attending a clinic in Los Angeles was assessed using a random, double-blind experiment. Both the treatment (T) and control (C) groups received similar vitamin and mineral supplements except that 20 mg zinc was added to the supplements for the treatment group. Nutrient intakes were calculated from 24-h recalls. The initial mean dietary zinc intake of both groups was about 50% of the Recommended Dietary Allowance (9 +/- 5 mg). Initially there were no significant differences between the two groups in mean zinc levels in serum (66 +/- 11 micrograms/dl, C, and 65 +/- 12 micrograms/dl, T) or in hair (184 +/- 41 micrograms/g, C, and 175 +/- 38 micrograms/g, T). Zinc supplementation did not alter mean zinc levels in serum or hair but significantly (p less than 0.05) reduced the number of low serum zinc values (less than or equal to 53.3 micrograms/dl) toward the end of pregnancy. Although serum zinc levels do decline in pregnancy, our results suggest that severely depressed levels (less than or equal to 50 to 55 micrograms/dl) indicate inadequate zinc status.

Adolescent↗
PubMed1983

The use of antikeratin antibodies in the diagnosis of human neoplasms.

The presence of intracellular keratin was examined in 230 human neoplasms using indirect immunofluorescence on fresh frozen, acetone-fixed sections. The use of antikeratin antibodies raised in rabbits against human callus and purified by affinity chromatography proved to be a rapid, sensitive, and reliable method of demonstrating keratin. Epithelial tissues and epithelial-derived neoplasms were found to contain keratin, whereas tissues and neoplasms of mesenchymal, lymphoreticular, or neural crest origin did not contain intracellular keratin. This technic is a useful adjunct for the surgical pathologist in the diagnosis of poorly differentiated neoplasms. Its application either confirmed, modified, or in several instances, changed the original light microscopic impression. The modified or changed diagnoses were confirmed by transmission electron microscopy.

Adult↗
PubMed1983

Analysis of non-response in a prospective study of depression in Los Angeles County.

The occurrence of depression in a probability sample of 1003 Los Angeles County adults was measured in a 1979-80 prospective cohort study. The primary measure of depression was the 20-item Center for Epidemiologic Studies-Depression (CES-D) scale. Of the original 1003 adults, 893 were successfully re-interviewed at a second time period (reasons for not being interviewed originally and at the second time period are given). Demographic data on those not re-interviewed are contrasted with data from those who did respond. The mean depression level and percentage classified as depressed at the first interview were higher in non-respondents than in respondents to the second interview. Techniques are given for assessing whether discontinued participation is due to exposure or disease factors. For this study, it was shown that dropping out of the study was mainly due to exposure (or demographic) factors and not to depression as such. Two methods for estimating the level of disease at the second time period for respondents and dropouts are illustrated.

Adolescent↗
PubMed1983

Depression, problem recognition, and professional consultation.

Data are from a 1979 community sample (n = 1000) of adults in Los Angeles County. The analysis examines how depressive symptoms, measured with the Center for Epidemiologic Studies Depression (CES-D) scale, and a variety of other factors influence problem recognition and use of mental health services. Of those people with a high level of depressive symptoms, nearly one third view themselves as having a nondepressive problem, while another third view themselves as having no personal problem. After controlling for demographic and other factors, depressive symptoms emerge as the most important element enhancing problem recognition; being female and having more education also enhance recognition of depressive problems and enable people to distinguish depressive from other problems. Among those with a high level of depressive symptoms, only one third had consulted a mental health service in the prior year. Factors promoting use of mental health services among those who acknowledge a personal problem include depressive symptoms, prior use of mental health services, use of services by friends and relatives, and discussion with friends and relatives about counseling; no significant effects emerge for sex, age, education, income, or insurance coverage. Data from the untreated show that a self-reliant attitude and some practical barriers prevent people with depressive symptoms from obtaining professional help.

Adult↗
PubMed1983

Comparison of lung function in young nonsmokers and smokers before and after initiation of the smoking habit. A prospective study.

It has been suggested that young persons who smoke have better lung function initially than those who remain nonsmokers. To examine this possibility prospectively, we analyzed respiratory questionnaire responses and lung function results in residents of Burbank and Lancaster, California, who had completed field screening studies of respiratory status at 2 times 5 yr apart. At Time 1 and Time 2, we calculated the age- and height-adjusted values for forced vital capacity (FVC) and forced expiratory volume in one second (FEV) of all white residents who at Time 1 were 13 to 23 yr of age and did not smoke tobacco. Dividing these into 2 groups, "starters" and "nonsmokers," we used analysis of covariance for males and females with height and age as covariates and compared lung function values at Times 1 and 2 and changes in lung function between these times. Among males at Time 1, FVC, FEV, peak expiratory flow, and maximal flow after exhalation of 25% of FVC were significantly larger for starters than for nonsmokers. At Time 2, values for these same indexes (except for FVC) were no longer significantly different between starters and nonsmokers. Our findings suggest that (1) relatively poor lung function may discourage young males (but not young females) from becoming regular tobacco smokers; (2) prediction equations based on so-called normal populations of nonsmokers might underestimate normal lung function, and (3) the adverse effect of smoking on lung function may be even greater than that estimated from cross-sectional studies.

Adolescent↗
PubMed1983

Immunohistochemical demonstration of keratins in human ovarian neoplasms. A comparison of methods.

A comparison of five immunohistochemical methods for the demonstration of keratins in human ovarian neoplasms using affinity-purified polyclonal rabbit antibody was made. The use of indirect immunofluorescence on frozen sections briefly fixed in acetone was found to be the most sensitive method and demonstrated keratin in all 14 primary and 1 metastatic ovarian epithelial neoplasms studied. Protein A-peroxidase, peroxidase--antiperoxidase (PAP), indirect peroxidase, or the avidin--biotinylated peroxidase complex (ABC) methods applied to formalin-fixed tissues were less sensitive and led to false negative results in 9 of 15, 1 of 15, 8 of 15, and 6 of 15 cases, respectively. A single case of dysgerminoma failed to reveal keratin by any method.

Female↗
PubMed1982

Factors associated with a malignant or benign course of multiple sclerosis.

Eight hundred thirty-four patients with multiple sclerosis (MS) in King and Pierce Counties, Washington, and in Los Angeles County, California, with symptomatic onset between 1960 and 1969 were followed up for disability status in 1980. A higher proportion of the 375 patients who were not walking or deceased in 1980 had a late age of onset, resided in Los Angeles County, had motor or coordination symptoms at onset, and reported adverse responses to heat exposure and favorable responses to cold exposure, whereas a higher proportion of the 299 patients still walking without aids had early onset age and vision, speech, or sensory symptoms, or all three, at onset. The results suggest (1) that both host factors (age at first manifestation of symptoms and types of symptoms at onset) and environmental factors (place of residence and exposure to heat and cold) are determinants of disease course and (2) that most patients with MS should avoid exposure to heat.

Adult↗
PubMed1982

Factors associated with a rapid course of multiple sclerosis.

A cohort of 886 cases of multiple sclerosis (MS) who had onset between Jan 1, 1960, and Dec 31, 1969, and who were resident in 1970 in either a low-prevalence area (Los Angeles County, California, 560 cases) or in a high-prevalence area (King and Pierce Counties, Washington, 326 cases) were followed up for changes in disability status through Dec 31, 1979. Cases had to meet the modified Schumacher criteria for definite/probable MS and to have had a diagnosis of MS or equivalent by a physician. Onset year of disease was determined by onset of the earliest reported symptom. Disability status was determined at intake by an interviewer-administered questionnaire and in subsequent years by an annual mailed questionnaire (self-reported disability status). Progression to a nonambulatory status or death was significantly greater among (1) patients with an older age at onset, (2) patients with a rapid early course, (3) males, and (4) residents of Los Angeles County.

Adult↗
PubMed1982

Studies of cervical caps: I. Vaginal lesions associated with use of the Vimule cap.

Prior to investigating the contraceptive efficacy of cervical caps, we undertook a preliminary study to evaluate potential side effects of these devices. Women who had not previously used a cap were randomly assigned to wear either a Vimule or Cavity Rim Cap (CRC) for as long as seven days. The Vimule cap caused lesions of the portio vaginalis ranging from erythematous impressions to abrasions and frank lacerations. There was variation in the degree of trauma depending, in part, on the size of the cap and duration of wear. Disruption of the epithelium occurred in eight of twelve Vimule users, but the lesions were sometimes difficult to see owing to their location. CRCs were worn by 20 women. This device sometimes left a "suction ring" on the cervix but did not disrupt the epithelium. Two of three long-term users of the Vimule cap who were also studied had unusual formations of the vaginal mucosa suggesting a proliferative reaction to chronic irritation. It is recommended that all women using a Vimule Cap be carefully re-examined and counseled about further use of the device according to the findings of the examination.

Adolescent↗
PubMed1982

Measuring depression in the community: a comparison of telephone and personal interviews.

Interview method effects in response to the Center for Epidemiologic Studies-Depression Scale (CES-D) are compared among a community sample (N = 546) of adults randomly assigned to either telephone or in-person interviews. The interviews were conducted in Los Angeles during 1980. No significant differences were observed between the two interview methods in nonresponse to symptom items, preference for specific response categories, reliability, mean level of depression, or proportion classified as depressed. Furthermore, no significant interactions were found between sociodemographic characteristics and the method of interview.

Adult↗