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Biomedical subjects

L Kahn

Publications and source records attributed to L Kahn.

At least 19 recordsLinked to original sources
PubMed1992

Expression of the amiloride-blockable Na+ channel by RNA from control versus aldosterone-stimulated tissue.

The amiloride-blockable Na+ channel was expressed in Xenopus oocytes injected with total RNA isolated from the toad urinary bladder. This system was used to investigate mechanisms that mediate the natriferic action of aldosterone. Incubation of the epithelium with aldosterone for 3 h doubled its channel activity but did not increase the ability of isolated RNA to express functional channels in oocytes. A 20-h incubation with the hormone produced an additional increase of Na+ transport across the intact epithelium and also augmented the channel activity expressed in oocytes by nearly 10-fold. The data are in agreement with our model that aldosterone enhances the apical Na+ permeability of tight epithelia by a short term activation of pre-existing channels, followed by chronic induction of new channel protein. Blocking methyl transfer reactions, previously shown to inhibit the natriferic action of aldosterone in tight epithelia, did not alter the basal or aldosterone-induced response in oocytes.

Aldosterone↗
PubMed1992

Prognostic factors in node-negative breast cancer.

One hundred patients with node-negative breast cancer were examined to analyze the influence of tumor size, nuclear grade, and DNA content determined by flow cytometry on overall survival. Patients with diploid cancers lived significantly longer than those with aneuploid cancers (126 +/- 8 vs 80 +/- 11 months). Patients with an S-phase fraction less than 10% lived significantly longer than those with S-phase fractions 10% or greater (122 +/- 8 vs 85 +/- 10 months). Tumor size had the major impact on survival, and multivariate analysis of variance by the Cox proportional hazards model showed the greatest effect on prognosis. Tumor grade did not significantly influence overall survival.

Breast Neoplasms↗
PubMed1988

Humanities now?

Explore the source record for details and available documents.

Education, Medical↗
PubMed1986

Effect of an inhibitor of DNA methylation on T cells. I. 5-Azacytidine induces T4 expression on T8+ T cells.

Maturing thymocytes express a series of cell surface glycoproteins which can be identified by monoclonal antibodies. The stage II or common thymocyte expresses the phenotype T4+T8+T6+T3-. In response to unknown signals, but presumably involving interactions with products of the major histocompatibility complex, the thymocyte suppresses either the T8 or T4 gene, becoming committed to the T4+T8- or T4-T8+ phenotype. With maturation, the thymocyte also becomes T6-T3+. To study whether DNA methylation may be involved in regulating expression of these determinants in mature T cells, we treated cloned interleukin 2-dependent T8- and T4-bearing T cells with 5-azacytidine (5-azaC), a nucleoside analog which inhibits methylation of newly synthesized DNA. In this report, we show that T8+ T cells treated with 5-azaC express the phenotype T8+T4+T6-T3+. Treatment of the same cells with hydroxyurea, an inhibitor of DNA synthesis, failed to induce T4 on T8+ cells. These results suggest that expression of the T4 gene may be suppressed by DNA methylation in mature T8+ cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1979

The influence of funding on the future of pediatric nurse practitioner programs.

Current funding sources threaten the future position of PNPs as providers of primary care. Most nurse practitioner programs of all disciplines including pediatrics rely for funds on the Division of Nursing, Bureau of Health Manpower, Department of Health, Education and Welfare. These funds are sufficient only for about half of currently operational programs and other sources of financing are not adequate to support the remainder. Another factor affecting the future of such programs is the trend to modify the preparation of the nurse practitioner from the clinically centered continuing education format to that based in schools of nursing and directed toward the MS degree. This is against the fundamental philosophy of the training of the PNP and will lead to diminishing participation of pediatricians in training programs. Unless there is evidence to show that the shift to graduate type education is fundamental to the competence of the nurse practitioner, the enthusiastic nurse who chooses to extend her professional skills should be allowed to do so without limiting this activity only to those who seek advanced academic degrees.

Education, Nursing↗
PubMed1978

The cost of a primary care teaching program in a prepaid group practice.

Costs were determined for a teaching program in general pediatrics and general internal medicine for advanced residents in a prepaid group practice, the Medical Care Group of Washington University. A time and motion study was conducted to measure the productivity of faculty physicians before and after the establishment of the teaching program. There was a statistically significant loss in productivity for internists and an apparent loss, though not significant, for pediatricians as a result of their teaching effort, but the productivity of the residents more than compensated for the loss. The residual positive value of a full time equivalent (FTE) pediatric resident after reimbursement of all possible lost productivity by faculty pediatricians represented 43.9 per cent of a FTE pediatrician. For a FTE resident in internal medicine the residual positive value was 49.7 per cent of a FTE internist.

Costs and Cost Analysis↗
PubMed1977

Comparability of two methods of time and motion study used in a clinical setting: work sampling and continuous observation.

Two methods of time and motion study, continuous observation and work sampling, were used to measure physician behavior in a prepaid group practice. Results of the two methods were compared to determine whether differences occurred because of method. No significant differences appeared in time/unit of patient service for 82 per cent of physicians studied, nor did the presence of the continuous observed affect the number of units of patient service/half day of observation. Nonpatient activities showed a slightly larger number of differences although 74 per cent of comparisons of mean activity times still showed none. Suggested causes for noted discrepancies may be circumstantial dissimilarities in the two study periods or observed proximity. Nonetheless, overall the two methods show a high degree of similarity. Unless there is particular interest in the exact content of the physician-patient encounter, when continuous observation is required, work sampling is preferred because of time, cost, and possible observed influence on nonpatient activities.

Group Practice↗
PubMed1977

Protein synthesis in muscle cultures from patients with myotonic dystrophy. Influence of A23187 ionophore and calcium: preliminary investigation.

Muscle samples for cultures were obtained from the tibialis anterior by open biopsy under local anesthesia in 12 patients with myotonic dystrophy and 15 controls. Total protein synthesis in muscle cultures from patients with myotonic dystrophy showed a nonsignificant increase in (3H)-leucine incorporation. Addition of A23187 ionophore significantly stimulated the protein synthesis in muscle cultures from patients with myotonic dystrophy, but had an inhibitory effect in the cultures from controls. Myosin heavy chain synthesis was measured and found normal in all patients with myotonic dystrophy.

Anti-Bacterial Agents↗
PubMed1977

The influence of a change in practice setting on pediatrician activity: a case study.

A time-and-motion study was performed of a pediatrician's activities in his fee-for-service solo practice and again after he joined a prepaid group practice. A comparison was made between time spent with fee patients in solo practice and time spent with fee patients continuing to see him in group practice. Total time per patient visit was not changed significantly by the group setting. Activities within the visit were modified in the group setting. History-taking and physical examination were reduced; counseling and charting were increased. Time spent in well-child visits in the group setting was significantly longer with the increased time spent in counseling. For sick visits there was no change in total time per visit nor in activities within the visit.

Fees and Charges↗
PubMed1977

The value of laparotomy in staging of lymphoma.

Seventy-one patients with lymphoma underwent staging laparotomy. Fifty of the patients had Hodgkin's disease and the remainder, non-Hodgkin's lymphoma. One patient died from pulmonary embolism on the tenth postoperative day, one required temporary assisted ventilation, one required reoperation for hemorrhage and six patients had infectious complications which responded to appropriate antibiotic therapy. Despite extensive noninvasive procedures, including bone marrow trephine biopsy and lymphangiography, in approximately 30% of the patients, the disease was restaged as a result of the operation. Since primary management of these diseases is critically dependent upon accurate staging, we conclude that, at the present time, this procedure is indispensible for proper management, as it contributes information not available from other currently used investigational techniques.

Adolescent↗
PubMed1976

The effects of an experimental prepaid group practice on medical care utilization and cost.

Rates of utilization and costs of medical care by a study group in a prepaid group practice, the Medical Care Group of Washington University (MCG), were compared prospectively over a three-year period with those of a demonstrably similar control group cared for by fee-for-service private physicians. MCG enrollees used twice the ambulatory services control enrollees did (p=less than 0.01), but used 23 per cent fewer hospital days (p=less than 0.01). Cost per diagnostic and therapeutic visit was similar for both groups; MCG preventive visits cost more. Increased numbers of MCG services provided led to increased ambulatory care costs for MCG over controls. Hospital utilization savings did not compensate for these increased costs. Thus prepayment in an organized setting did change hospital and ambulatory care utilization but did not reduce medical care costs. Other changes in medical care besides those which result from a different organization of medical care are discussed which might make control of medical care costs more likely.

Adult↗
PubMed1975

Lack of effect of an experimental prepaid group practice on utilization of surgical care.

The utilization of surgical care in an experimental period group practice for a 3 year period is reported. In contrast to what was expected, prepaid enrollees used the same or more surgical care than did control enrollees. The same proportion of emergency, urgent, and nonurgent admissions, occurred in both groups. Likewise there was no difference in the proportion of various procedures often thought to be overutilized in the traditional medical care system. High quality of surgical care in the area where the study was conducted was considered the most likely explanation for failure to show differences in the prepaid growth practice. Few, if any, unnecessary operations were performed in either group studied. Thus, under the conditions of this study, no significant measurable effect on surgical utilization by a change in the method of medical care organization and payment could be demonstrated.

Adult↗