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Biomedical subjects

M Lipkin

Publications and source records attributed to M Lipkin.

At least 91 records · Page 5Linked to original sources
PubMed1993

Doctors as workers: work-hour regulations and interns' perceptions of responsibility, quality of care, and training.

OBJECTIVE: To study residents' perceptions of their responsibility for patients, the quality of patient care, and their learning experiences in light of new work-hour regulations. DESIGN: Inductive analysis of in-depth, semistructured, recorded interviews with a cohort of interns in internal medicine in the last month of their first postgraduate year. Questions were grounded in an examination of issues related to going off duty and delegating tasks to colleagues. Transcripts were independently analyzed by an interdisciplinary team. SETTING: New York University/Bellevue Hospital Center's residency program in internal medicine (in New York City). PARTICIPANTS: A cohort of 21 of a possible 24 interns in medicine on rotation at Bellevue Hospital Center. RESULTS: The interviews revealed: 1) intense concern harbored by interns for their patients with resulting difficulty in maintaining realistic boundaries between work and personal lives; 2) an open-ended workday and competing considerations confronting interns when deciding to leave the hospital--including concerns about leaving patients at critical junctures in their care, confidence in the colleague to whom they were signing out, regard for the workload of this colleague, and uneasiness about the educational consequences; 3) deterrents to acknowledging and acting on one's limits in performing medical work; and 4) a recurrent conflict between delegating responsibility and retaining control over patient care. CONCLUSION: Values traditionally learned in training emphasize autonomy and individual accountability. They may conflict with the shared decision making and collective responsibility among peers necessitated by work-hour limitations and associated changes in program structure.

Attitude of Health Personnel↗
PubMed1993

Physician satisfaction with primary care office visits. Collaborative Study Group of the American Academy on Physician and Patient.

To study encounter-specific physician satisfaction we collected exit questionnaires from patients and physicians following 550 primary care office visits. The physicians' questionnaire included 20 items pertaining to satisfaction with the visit, one of which was an assessment of global satisfaction. Using a boot-strap technique, we factor analyzed the satisfaction questions in 10 repeated samples. Four distinct dimensions of physician satisfaction emerged: satisfaction with the patient-physician relationship, with the data collection process, with the appropriateness of the use of time, and with the absence of excessive demands on the part of the patient. Each scale was found to be reliable; global satisfaction was most closely related to the relationship factor. Satisfaction with use of time and the adequacy of data collection tended to be stable for individual physicians across a range of patients whereas global satisfaction and satisfaction with the relationship and the demanding nature of the patient and were more variable, hence most unique to each encounter. This study of physician satisfaction represents an effort to incorporate knowledge about physicians' subjective experiences into a systematic understanding of the dynamics of the medical interview.

Attitude of Health Personnel↗
PubMed1993

Effects of sennosides and nonanthranoid laxatives on cytochemistry of epithelial cells in rat colon.

The cytochemical effects of laxatives on rat colonic epithelial cells were studied. A total of 32 rats was divided into four groups. Three groups were treated with bisacodyl, picosulfate and sennosides for 12 weeks, and a fourth group served as control. The rectum, midcolon and cecum were studied for acidic mucins, lectin soybean agglutinin (SBA) and cytokeratin AE1. Most striking and consistent changes were found in the rectum including total acidic mucin content which significantly increased, with sulfomucin decreased and sialomucin increased in the three treatment groups. Cytokeratin AE1 expression increased on picosulfate and sennosides. SBA total binding increased on bisacodyl and picosulfate. The present findings were thought to be of functional origin and do not represent early precancerous lesions.

Animals↗
PubMed1993

Proliferation and differentiation biomarkers in colorectal mucosa and their application to chemoprevention studies.

Colorectal cancer is one of the leading causes of morbidity and mortality in Western countries. Because its prognosis is relatively unaffected by improvements in surgery and chemotherapy, increasing interest has recently been directed toward chemoprevention. Intermediate biomarkers of abnormal cell proliferation, differentiation, and gene expression have recently been identified and have served to measure effects of chemopreventive agents in rodent models and in short-term human clinical trials. Alterations in cell proliferation and differentiation have been found in preneoplastic diseases and in normal-appearing colorectal mucosa of patients at increased risk for malignancy. Several techniques are available for measuring these alterations, and standardization and comparison of different methods are underway to assess the utility of various intermediate biomarkers in chemoprevention studies.

Biomarkers↗
PubMed1993

A comparison of work-sampling and time-and-motion techniques for studies in health services research.

OBJECTIVE: This study compares results and illustrates trade-offs between work-sampling and time-and-motion methodologies. DATA SOURCES: Data are from time-and-motion measurements of a sample of medical residents in two large urban hospitals. STUDY DESIGN: The study contrasts the precision of work-sampling and time-and-motion techniques using data actually collected using the time-and-motion approach. That data set was used to generate a simulated set of work-sampling data points. DATA COLLECTION/EXTRACTION METHODS: Trained observers followed residents during their 24-hour day and recorded the start and end time of each activity performed by the resident. The activities were coded and then grouped into ten major categories. Work-sampling data were derived from the raw time-and-motion data for hourly, half-hourly, and quarter-hourly observations. PRINCIPAL FINDINGS: The actual time spent on different tasks as assessed by the time-and-motion analysis differed from the percent of time projected by work-sampling. The work-sampling results differed by 20 percent or more of the estimated value for eight of the ten activities. As expected, the standard deviation decreases as work-sampling observations become more frequent. CONCLUSIONS: Findings indicate that the work-sampling approach, as commonly employed, may not provide an acceptably precise approximation of the result that would be obtained by time-and-motion observations.

Bias↗
PubMed1992

Modulation of colonic epithelial cell proliferation, histone acetylation, and luminal short chain fatty acids by variation of dietary fiber (wheat bran) in rats.

The effect of increasing amounts of wheat bran (0, 5, 10, 20%) in AIN-76 semisynthetic diet on colonic luminal short chain fatty acids, epithelial cell histone acetylation, and cytokinetics, was studied for 2 weeks in groups of 10 male Sprague-Dawley rats. Luminal contents were removed from the colon at sacrifice, quick frozen, and analyzed for short chain fatty acids by gas-liquid chromatography. Histone acetylation was assessed in cells isolated from the same animals. Cell proliferation was measured after a short pulse in vivo with [3H]thymidine. Colonic luminal butyrate levels were lower in the 0 and 20% fiber groups, and higher in the 5 and 10% fiber groups. In contrast, cell proliferation, as determined by labeling index, was higher in the 0 and 20% fiber groups, and lower in the 5 and 10% fiber groups. This resulted in a significant inverse correlation between luminal butyrate levels and colonic cell proliferation. In addition, there was a positive linear correlation between luminal butyric acid levels and colon epithelial cell histone acetylation. From these data it was concluded that colonic butyrate levels can be modulated by the addition of wheat bran to the diet and that butyrate can modulate DNA synthesis (calculated as labeling index) in the proliferative compartments of colonic crypts. The localization of dividing cells was unchanged and no induction of terminal differentiation was detectable (contrary to what has been observed for transformed cells in culture).

Acetylation↗
PubMed1992

Calcium, vitamin D, and colon cancer.

Calcium contributes to the progression of epithelial cells through all phases of the proliferative cycle and into stages of cell differentiation; intracellular concentrations of calcium that are required for cell renewal, however, are lower than those required for epithelial-cell differentiation. These effects of calcium are modulated by interactions with 1,25-dihydroxy-vitamin D3, phosphate, and fatty acids, all of which are partly dependent on dietary intake. In rodent models, increased dietary calcium inhibited hyperproliferation of colon epithelial cells induced by increased levels of fatty acids or bile acids present in the colon. When carcinogens induced hyperproliferation of colon epithelial cells the hyperproliferation was decreased by added dietary calcium, and in several animal models the occurrence of carcinogen-induced carcinomas of the colon decreased with increased dietary calcium. A nutritional stress diet, designed to represent human Western dietary intake of calcium, phosphate, vitamin D, and fat, produced hyperproliferation and hyperplasia in the colons of rodents; these effects were reduced by increasing dietary levels of calcium. Decreased levels of ornithine decarboxylase also were reported in human and rodent colon mucosa exposed to increasing levels of calcium. In human subjects at increased risk for familial colon cancer, hyperproliferation of colon epithelial cells was reduced after oral dietary supplementation with calcium. In epidemiological studies, several investigators reported inverse correlations between levels of dietary calcium intake and the incidence of colon cancer. Extrapolation of the data have suggested a protective effect of total calcium intakes above 1500 to 1800 mg/day.

1,2-Dimethylhydrazine↗
PubMed1992

Gastrointestinal cancer: pathogenesis, risk factors and the development of intermediate biomarkers for chemoprevention studies.

Dietary, environmental and genetic factors contribute to the etiology, pathogenesis and risk for gastrointestinal cancers. Measurements of cell proliferation and differentiation further identify abnormal cellular properties associated with increased susceptibility to gastrointestinal cancer. In precancerous esophagus, the proliferative compartment increases in size, increased ploidy and dysplasia develop, and epithelial cells express abnormal cytokeratins and ectopic tumor-associated antigens. In precancerous stomach, increased proliferative activity and metaplasia develop. Intestinal enzymes and mucins are expressed and normal gastric antigens are replaced by intestinal or embryonic antigens. In flat colonic mucosa and in colonic adenomas, expansions of the proliferative compartment occur. Gene expression is modified, gene deletions occur and blood group-related antigens are modified as the cells undergo abnormal differentiation and develop into adenomas and carcinomas. Chemopreventive regimens are now being tested to determine whether they modify such intermediate biomarkers toward normal levels characteristic of lower risk for neoplasia. It is anticipated that the utilization of intermediate biomarkers in chemoprevention studies may permit more novel chemopreventive regimens to be tested in human subjects than heretofore was possible.

Anticarcinogenic Agents↗
PubMed1992

Intermediate biomarkers of increased risk for colorectal cancer: comparison of different methods of analysis and modifications by chemopreventive interventions.

Intermediate biomarkers of abnormal cell growth and development have recently been used in chemoprevention trials in attempts to identify the efficacy of chemopreventive agents in human subjects. Measurements carried out include those related to cell proliferation, differentiation, and gene structure and expression in the colon. Among modified patterns of cell proliferation identified by microautoradiographic or immunoperoxidase assays, a characteristic expansion in the size of the proliferative compartment has been observed in normal-appearing colorectal mucosa of human subjects with disease increasing cancer risk; the same patterns have been induced by chemical carcinogens in rodents. Moreover, this intermediate biomarker has been modulated by chemopreventive agents in both rodents and humans. Newer intermediate biomarkers being studied for application to human chemopreventive programs include normal and abnormal patterns of expression of mucins, intermediate filaments and cytoskeletal proteins, and the structure and expression of a variety of genes associated with normal and abnormal cell development. The application of these various intermediate biomarkers to chemoprevention studies is increasing the ability of investigators to analyze the effects of novel chemopreventive agents in the colon and in other organs.

Anticarcinogenic Agents↗
PubMed1992

Precancerous lesions of the human esophagus: multiparametric study of esophageal biopsies from a high-risk population in Linxian, China.

Histopathology, morphometry, tritiated thymidine incorporation and immunohistochemistry were studied in 221 esophageal biopsies from subjects with cytologica hyperplasia in Linxian, China. A spectrum of 7 morphologic entities were found: (1) normal/near normal (NN); (2) basal cell hyperplasia 0 (BHO); (3) simple hyperplasia (SH); (4) mixed basal and spinous cell hyperplasia (MBS); (5) basal cell hyperplasia 1 (BH1); (6) dysplasia (D); and (7) non-proliferative lesion (NP). Forty percent of the biopsies had combinations of histologic types. The thickness of the epithelium was increased in SH, MBS, and BH1, but not in BHO and NP. Elongation of papillae was frequently seen in SH, MBS, BH1, and D. Papillary bleeding was very prevalent in the esophageal specimens studied. A variety of cellular changes were found in peripapillary areas especially when bleeding occurred. [3H]-thymidine labeling index was dramatically increased in the entire epithelium in dysplasia, and also increased in cell layer 3 of MBS, BH1 and D. Blood group antigen LeY and lectin WGA showed consistent positivity in cellular membranes of the squamous cells, and these changes occurred before gross morphologic alterations. These findings provide a hypothesis for the sequence of pathogenetic events leading to esophageal carcinoma, and define each step with corresponding biomarkers for cancer prevention studies.

Biopsy↗
PubMed1992

The potential for using non-physicians to compensate for the reduced availability of residents.

Both the number of residents and the amount of time existing residents have in which to carry out their activities may soon be decreasing. To consider the potential for alternative ways of staffing teaching hospitals, it is necessary to know how residents spend their time. The authors sought to learn this by conducting a time-motion study of eight internal medicine residents at two urban hospitals in New York City in 1988. The residents' activities were observed and coded by premedical students, and the authors independently classified the possible activities into (1) those that had to be done by a physician, (2) those that were educational only, and (3) those that could be done by a non-physician. A total of 1,726 activities of 67 kinds were coded, averaging 7.75 minutes each. The authors analyze and project their data using two models--the traditional model of care in which the physician is the primary medical manager of the patient, and an alternative model in which a midlevel practitioner, such as a nurse practitioner, would perform the day-to-day monitoring of patients. For example, the data indicate that in the traditional model, almost half of a resident's time is spent in activities that must be done by a physician, meaning that another kind of physician would be needed to do those activities if the resident were unavailable; but in the midlevel practitioner model, only around 20% of the activities would require a physician. The authors give detailed breakdowns of their data, estimate the kinds and numbers of non-physician health care professionals necessary to substitute for residents in appropriate activities, and review possible difficulties in implementing such substitutions.

Evaluation Studies as Topic↗
PubMed1992

The California Family Health Project: I. Introduction and a description of adult health.

Little research has addressed patterns of family and health relationships that reflect both the scope and complexity of family life and the breadth and diversity of health. In the first of a series of articles, we describe the California Family Health Project, a study in which four large "domains" of family life (Structure/Organization, World View, Problem Solving, and Emotional Management) were mapped, described, and compared with a large battery of adult health measures. We first present a brief critical overview of the literature on family and health research, then explain our rationale, define our approach to the multivariate analysis of family and health data, and describe our sample of 225 community-based families. To prepare for analyses with the family variables, we next present descriptive data based on separate principal components analysis (PCA) and multidimensional scaling analysis (MDS) of 14 self-reported health scores for husbands and for wives. No grouping or clustering of health variables emerged for either husbands or wives in the PCAs. A two-dimensional MDS analysis for husbands and for wives displayed the health variables in a circular pattern in which no predominant descriptive dimension or group of discrete dimensions emerged. Consequently, we decided that all 14 health scores will be used in the analyses, with the family variables to follow.

Adult↗
PubMed1991

Patterns of gene expression that characterize the colonic mucosa in patients at genetic risk for colonic cancer.

We have used a computer-driven scanning and image-processing system to identify a panel of 30 cDNA clones whose pattern of expression in individual biopsy specimens distinguishes the flat, normal-appearing colonic mucosa of patients in two genetic groups at high risk for development of colorectal cancer from that of normal colonic mucosa in low-risk individuals. The two high-risk groups, familial adenomatous polyposis and hereditary nonpolyposis colon cancer, are indistinguishable based on the pattern of expression of the 30 selected clones. This suggests that the extensive pleiotropic effects of the inherited loci, which may play an important role in the mechanism of increased risk and early onset of the disease, are similar in these populations.

Adenomatous Polyposis Coli↗