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Biomedical subjects

V A Clark

Publications and source records attributed to V A Clark.

At least 37 records · Page 2Linked to original sources
PubMed1989

Bone mineral content in postmenopausal women: comparison of omnivores and vegetarians.

This cross-sectional study of bone mineral content (BMC)/bone width (BW) (BMC/BW, cortical radius) was conducted in elderly, free-living Methodist omnivores (n = 146) and Seventh-day Adventist vegetarians (n = 144) in southern California. The purpose was to investigate relationships between BMC/BW and dietary factors (primarily vegetarianism and intakes of protein and calcium) and use of prescribed drugs. BMC was measured by single-photon absorptiometry. Dietary intakes during current and early periods of life were assessed by 24-h dietary recall and frequency methods. Information about drug use was obtained by interview. BMC/BW was not different in omnivores vs vegetarians. There were no significant relationships or trends between current or early dietary intakes and BMC/BW in either group. In multiple-regression analysis, age, weight, and use of estrogen and thiazide diuretics were predictive of 31% of the variability in BMC/BW in the total group.

Anthropometry↗
PubMed1988

Decreased serum cotinine levels in smokers of both tobacco and marijuana as compared with smokers of tobacco only.

Serum and salivary cotinine levels were determined in tobacco smokers (n = 125) who smoked only tobacco (n = 47) or who smoked both marijuana and tobacco (n = 78) as part of a field study of the pulmonary effects of heavy, habitual use of marijuana alone or with tobacco. After adjustment for current daily amount of tobacco use and time since the last tobacco cigarette was smoked, the smokers of both marijuana and tobacco were found to have lower levels of cotinine than those who smoked only tobacco, in serum [258 +/- 113 ng/ml (S.D.) and 332 +/- 109, respectively; p = 0.003] and in saliva (331 +/- 170 and 395 +/- 170, respectively; p = 0.058). Serum cotinine showed a significantly negative relationship to the daily amount of marijuana currently smoked (p = 0.026). Possible explanations include inhibition by marijuana component(s) of the enzymes that participate in the conversion of nicotine to cotinine, differences in nicotine absorption patterns between the two groups of tobacco smokers, and acceleration of cotinine metabolism by marijuana smoking. Carefully controlled pharmacokinetic studies, not possible in a large-scale survey such as this one, are required both to confirm the differences in blood cotinine levels observed between the dual smokers and smokers of tobacco only and to define more clearly nicotine-marijuana interactions.

Adult↗
PubMed1988

Metered-dose inhaler usage in subjects with asthma: comparison of Nebulizer Chronolog and daily diary recordings.

The Nebulizer Chronolog (NC) is a portable electronic device that attaches to standard metered-dose inhalers (MDIs) and records and stores the date and time of each MDI actuation. We evaluated the long-term performance of the NC and compared its data to concurrent recordings of self-administered MDI usage in daily diaries. Eighty-three subjects with asthma were evaluated during a 7 1/2-month panel study of air pollution effects. Although 44 (53%) of the NCs developed a malfunction during the study, the average total (+/- SD) percentage of useful days with functioning NCs was still 86 +/- 18% (median 93%). The agreement between the daily diary and NC recordings was very high, that is, 50 (67%) of 75 subjects had perfect agreement. Eighteen subjects with over or under diary reporting were detected. We conclude that the NC is an effective, objective, accurate, and continuous monitor of daily MDI usage despite some remediable technical problems. The NC can facilitate the evaluation of short- and long-term medication usage patterns and compliance issues in MDI-related research and clinical settings.

Adolescent↗
PubMed1988

Personal health habits and symptoms of depression at the community level.

This investigation examined the relationship between lifestyle, as defined by common health habits, and symptoms of depression in a general community sample. The study was conducted using data from a longitudinal survey involving four interviews of 1,003 Los Angeles County adults. The survey focused on the epidemiology of depression and help-seeking behavior, which included questions about seven health habits identified in the Alameda County Study as predictive of health status. The group used for this analysis comprised 752 adults who participated in and had usable depression scores (as measured with the 20-item CES-D scale) at all interviews. Depression prevalence rates were higher for six of the seven "poor" health habits examined compared with the "good" health habit. Prevalence odds ratios were greater than 2.0 for poor sleeping and drinking habits (both sexes) and equaled 1.8, among women only, for poor physical activity and smoking habits. Multivariate regression analyses showed a simple sum of the total number of good habits to be a significant independent predictor of depression after controlling for prior depression and various sociodemographic factors. The finding of an independent contribution of health habits to depression status emphasizes that lifestyle may influence mental as well as physical health.

Adult↗
PubMed1987

Cytokeratin characterization of human prostatic carcinoma and its derived cell lines.

Two murine monoclonal anti-cytokeratin antibodies with defined specificity were shown to distinguish between basal cells and luminal cells in human prostate tissue. Forty-one biopsies or transurethral resection specimens were characterized using these two antibodies. In cases of benign prostatic hyperplasia, focal loss of the basal cell layer was noted in areas of glandular proliferation. Ten cases of adenocarcinoma of the prostate, varying in Gleason's histological grade from 2 to 4, were also studied. In each case the carcinoma was shown to represent the luminal cell phenotype with no evidence of involvement of the basal cell phenotype. An analysis of three established metastatic prostatic carcinoma cell lines (DU-145, PC-3, and LNCaP) using two-dimensional electrophoresis showed that the cytokeratin complement of each cell line was slightly different but retained the phenotype of the luminal cell. It was concluded that during both hyperplasia and neoplastic transformation of the prostate, the luminal cell phenotype is primarily involved and that the basal cell phenotype does not appear to contribute to either intraluminal proliferation or invasive cell populations.

Antibodies, Monoclonal↗
PubMed1987

Respiratory symptoms and lung function in habitual heavy smokers of marijuana alone, smokers of marijuana and tobacco, smokers of tobacco alone, and nonsmokers.

To evaluate the possible pulmonary effects of habitual marijuana smoking with and without tobacco, we administered a detailed respiratory and drug use questionnaire and/or lung function tests to young, habitual, heavy smokers of marijuana alone (n = 144) or with tobacco (n = 135) and control subjects of similar age who smoked tobacco alone (n = 70) or were nonsmokers (n = 97). Mean amounts of marijuana and/or tobacco smoked were 49 to 57 joint-years marijuana (average daily number of joints times number of years smoked) and 16 to 22 pack-years of tobacco. Among the smokers of marijuana and/or tobacco, prevalence of chronic cough (18 to 24%), sputum production (20 to 26%), wheeze (25 to 37%) and greater than 1 prolonged acute bronchitic episode during the previous 3 yr (10 to 14%) was significantly higher than in the nonsmokers (p less than 0.05, chi square). No difference in prevalence of chronic cough, sputum production, or wheeze was noted between the marijuana and tobacco smokers, nor were there additive effects of marijuana and tobacco on symptom prevalence. We noted significant worsening effects of marijuana but not to tobacco on specific airway conductance and airway resistance (tests of mainly large airways function) in men and of tobacco but not of marijuana on carbon monoxide diffusing capacity and on closing volume, closing capacity, and the slope of Phase III of the single-breath nitrogen washout curve (tests reflecting mainly small airways function) (p less than 0.03, two-way ANCOVA). No adverse interactive effects of marijuana and tobacco on lung function were found.

Adult↗
PubMed1987

Respiratory effects of cocaine "freebasing" among habitual users of marijuana with or without tobacco.

Use of cocaine by smoking its alkaline precursor ("freebasing") has become increasingly prevalent. Recent studies of small numbers of cocaine users suggest that freebasing frequently causes cough, dyspnea, and abnormalities in diffusing capacity (DCO), although these findings could have been due to concomitant use of other drugs. We therefore evaluated the relationship between cocaine use by freebasing and chronic respiratory symptoms and lung dysfunction in a large sample of habitual smokers of marijuana with or without tobacco who denied intravenous drug abuse. The findings suggested that, among habitual marijuana smokers, "moderate" cocaine smoking damaged both large and small airways, as reflected by functional changes that were independent of concomitant marijuana use and appeared to be synergistic with the effects of tobacco. On the other hand, no adverse influence of cocaine smoking on the pulmonary microcirculation was demonstrated in our sample of freebase users.

Adult↗
PubMed1987

Educating physicians and treating patients in the ambulatory setting. Where are we going and how will we know when we arrive?

We evaluated 15 group practices in general internal medicine in university hospitals with regard to access to and quality of care, patients' satisfaction with that care, and quality of residency education provided. We used these data to speculate about potential changes in ambulatory care programs in university teaching hospitals. All 15 practices participated for 4 years. One third of their patient population had no medical insurance. Practice patients had twice as many chronic illnesses as did the general population, and two fifths of patients stayed at least 2 years in the practice. Few faculty members spent more than 14 hours weekly in the practices, and housestaff worked an average of 4 hours per week. Patient waiting times did not meet ideal standards, but patient satisfaction was higher than in a general population. Compliance with quality of care criteria was not exceptional; for example, 10% of eligible patients received an annual influenza vaccination. Housestaff assigned a relatively low ranking to their educational experience in the practices. We recommend the institution of additional experimental programs in ambulatory care and housestaff education to improve the quality of care in the ambulatory setting.

Continuity of Patient Care↗
PubMed1987

Providing primary general medical care in university hospitals: efficiency and cost.

Data on efficiency, costs, and profits of 15 internal medicine outpatient group practices in university hospitals were collected for 9 months from interviews, a time-motion study, observations, and reviews of bills. Charges for a follow-up visit were about 25% higher than Medicare's allowable charges, but differed threefold across practices. Physicians spent more than half their allocated patient care or supervision time in other activities and 14% of nursing time was used for direct patient care. Visits to second- and third-year residents cost one half of those to faculty. Faculty supervision of second- and third-year residents was limited; it was, on average, 2 minutes per follow-up visit. Despite these inefficiencies, bad debts, and educational costs, practices appeared to break even financially. We conclude it is financially feasible for university hospitals to provide primary care to disadvantaged populations.

Costs and Cost Analysis↗
PubMed1986

Comparison of the usefulness of histochemistry and ultrastructural cytochemistry in the identification of neuroendocrine neoplasms.

Neuroendocrine (NE) neoplasms range from well to poorly differentiated types. These neoplasms usually contain neurosecretory (NS) granules demonstrated by either transmission electron microscopy (TEM) or silver reduction methods. By using the uranaffin reaction, one can differentiate NSG from other membrane-bound organelles. Recently, a variety of antibodies reactive against specific peptides or neurotransmitter substances have been advocated as being diagnostically useful. Using the peroxidase-anti-peroxidase (PAP) or Avidin-Biotin technics, we studied 41 NE neoplasms using anti-sera specific for neurospecific enolase (NSE), bombesin, adrenocorticotropic hormone (ACTH), calcitonin, and serotonin. All cases were shown to contain NS granules with a positive uranaffin reaction. In all 25 well-differentiated cases, at least one anti-serum gave a positive reaction. NSE was positive in 22 of the 25. In the poorly differentiated group, 7 (43.2%) of 16 were negative for all anti-sera tested. In these negative cases TEM using the uranaffin reaction remains an important diagnostic test.

Cytoplasmic Granules↗
PubMed1986

Evaluation of ambulatory care training by graduates of internal medicine residencies.

In 1984, 154 physicians who had completed residencies in internal medicine at 15 major teaching hospitals in 1982 evaluated their residency training in ambulatory care. A majority of the physicians would have liked more experience in practical areas related to career planning and office management, more input from subspecialties such as orthopedics and dermatology, greater knowledge about the management of psychosocial problems, and more information about exercise and nutrition. Although many physicians also wanted more time devoted to several other topics, less than 20 percent recommended spending less time on 26 of the 27 topics being evaluated. Since these recommendations are similar to those reported in evaluation studies published over the past 25 years, it appears that training programs in internal medicine have not been successful in restructuring their curricula to meet many of the needs of practicing physicians.

Ambulatory Care↗
PubMed1985

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

As a follow-up of our study of pregnant women, we report effects of zinc supplementation during pregnancy in another population of 138 Hispanic teenagers in Los Angeles. Teenagers were randomized (double-blind) to a control or zinc-supplemented group and received similar daily vitamin and mineral supplements except for 20 mg zinc added to the zinc-supplemented group's capsules. Initially, mean dietary zinc intakes of both groups were about 50% of the Recommended Dietary Allowance and their mean serum zinc levels did not differ significantly (69.8 +/- 11.2 micrograms/dl in control and 69.0 +/- 11.4 micrograms/dl in zinc-supplemented group). Zinc supplementation did not maintain mean serum zinc levels during pregnancy but, as in our earlier study, it reduced (p = 0.018) the number of low serum zinc values (less than or equal to 53 micrograms/dl) in late pregnancy. Zinc supplementation did not affect outcome of pregnancy but serum zinc levels were lower (p = 0.038) in teenagers with pregnancy-induced hypertension than in normotensives.

Adolescent↗
PubMed1985

Paget's cells. New evidence linking mammary and extramammary Paget cells to a common cell phenotype.

Three mouse monoclonal anti-human cytokeratin antibodies were made against human sole epidermis. One of these (KA4) was shown to react with a variety of human simple epithelium, including eccrine and apocrine sweat glands and the luminal cells of the breast ducts and lobules, but failed to decorate interfollicular stratified squamous epithelium. This antibody reacted by the immunoblot technic with cytokeratins of Mr values 54, 46, and 40 kdaltons. KA4 reacted strongly with clear cells found in 11% of breast epithelium in clinically uninvolved nipples and with all Paget's cells in four cases of mammary and five cases of extramammary Paget's disease. These findings suggest a common cellular phenotype for Paget's cells and relates them to a population of cells found in breast epithelium.

Aged↗
PubMed1985

Physician and patient satisfaction as factors related to the organization of internal medicine group practices.

The present study compares patient satisfaction scores with job satisfaction scores of the physicians providing their care in 16 general internal medicine teaching hospital group practices. Practice sites with more satisfied patients were also more likely to have more satisfied housestaff and faculty physicians. Additionally, higher satisfaction scores for both physician groups and patients were consistently associated with a greater percentage of patients experiencing continuity of care, lower patient no-show rates, more efficient use of ancillary staff in providing direct patient care, and more reasonable charges for a routine follow-up visit. These findings suggest that improving physician and patient satisfaction may have economic as well as psychological and social benefits.

Consumer Behavior↗
PubMed1985

General medical care and the education of internists in university hospitals. An evaluation of the teaching hospital general medicine group practice program.

Fifteen general internal medicine group practices in university teaching hospitals were studied to evaluate their primary care services and education. Data were collected over 9 months from physicians, patients, and medical records, and by observation. All institutions had closed their general medical clinics. Many patients being treated in group practices were very sick; 57% had hypertension; 21% were diabetic; and 45% could not work. Most were satisfied with their care. Care for acute problems from a health care provider in the practice was available quickly; regular physicians were harder to see. House staff and faculty spent little time in the practices. Few practices used teams; most used traditional attending and house staff models. Practice physicians could not easily determine when patients were seen in the institution's emergency department or were hospitalized. Quality of care standards were not uniformly met. Finally, the structure of academic centers appeared to inhibit the practices' performance, suggesting a need for further appraisal of relationships between university hospitals and their ambulatory care units.

Appointments and Schedules↗
PubMed1984

Ovarian failure following cytotoxic therapy.

Evidence of ovarian failure was sought in 18 premenopausal women who were being treated with cytotoxic drugs for malignant disease. Ten had symptoms and signs of ovarian failure although only two had conveyed these problems to us. Ovarian failure was more frequently observed in patients over 25 and in those on continuous low doses of alkylating agents such as busulphan. Oestrogen/progesterone replacement therapy together with appropriate counselling was given to eight women and brought great benefit to them all. Provided there is no danger of activating the tumour, cytotoxic induced ovarian failure should be treated promptly with replacement therapy even if life expectation is short.

Adolescent↗