Search PubMed⌕ Search

Biomedical subjects

R H Lee

Publications and source records attributed to R H Lee.

At least 91 records · Page 5Linked to original sources
PubMed1985

Hydrophobicity of amino acid residues in globular proteins.

During biosynthesis, a globular protein folds into a tight particle with an interior core that is shielded from the surrounding solvent. The hydrophobic effect is thought to play a key role in mediating this process: nonpolar residues expelled from water engender a molecular interior where they can be buried. Paradoxically, results of earlier quantitative analyses have suggested that the tendency for nonpolar residues to be buried within proteins is weak. However, such analyses merely classify residues as either "exposed" or "buried." In the experiment reported in this article proteins of known structure were used to measure the average area that each residue buries upon folding. This characteristic quantity, the average area buried, is correlated with residue hydrophobicity.

Amino Acids↗
PubMed1985

The demand for residents.

This paper develops an empirical model of the demand for medical residents. Not-for-profit teaching hospitals are viewed as firms facing shadow prices that differ from market prices, and the impacts of variations in stipends in the quality of training, in the cost of teaching, and in hospitals' objectives on the shadow cost of hiring residents are made explicit. Empirical results from three data sets are shown to be consistent with a simple derived demand model, and the indirect effects of increased competition and cost control initiatives on the demand for residents are assessed.

Economics, Hospital↗
PubMed1985

The diffusion of innovations in hospitals. Some econometric considerations.

Empirical studies of the diffusion of innovations have not addressed adequately econometric problems that are characteristic of such analyses. Reanalysis of data for five innovations using an estimator with desirable statistical properties results in a considerably revised estimate of the impact of prospective reimbursement on diffusion.

Capital Expenditures↗
PubMed1985

Phosphodiesterase-probes show distinct defects in rd mice and Irish setter dog disorders.

The phosphodiesterase from the visual cells of rd mice and affected Irish setter dogs has been analyzed, using biochemical, biophysical, and immunological techniques. The authors' findings demonstrate that the mechanisms that cause a deficiency in phosphodiesterase activity in rd mice and Irish setter dogs are distinctly different. Apparently, the phosphodiesterase complex is normal in affected Irish setter dogs but is abnormal in rd mice. The criteria used for determining the normalcy of the phosphodiesterase complex were sedimentation characteristics, immuno-cross-reactivity, and histone-activation, which is shown to be a unique characteristic of the visual cell enzyme. According to these criteria, the phosphodiesterase complex in the visual cells of rd mice is either absent or abnormal from the onset of visual cell differentiation until degeneration, because it exhibits no cross-reactivity with antibody to phosphodiesterase; it is not activated by histone; and if present, it exhibits abnormal sedimentation characteristics and perhaps subunit structure. On the other hand, phosphodiesterase from the visual cells of affected Irish setter dogs is normal by the same criteria, because it cross-reacts with antibody against phosphodiesterase; it is activated by histone; and it exhibits normal sedimentation and electrophoretic patterns. It is proposed that depressed levels of phosphodiesterase activity in affected setter photoreceptors are due, perhaps, to a defect in the light-initiated cascade which activates the enzyme normally, in situ.

Animals↗
PubMed1984

Light-induced dephosphorylation of a 33K protein in rod outer segments of rat retina.

Phosphorylated proteins may play an important role in regulating the metabolism or function of rod photoreceptors. In mammalian retinas, a photoreceptor protein of 33 000 (33K) molecular weight is phosphorylated in a cyclic nucleotide dependent manner in vitro. Since light initiates the activation of a photoreceptor-specific phosphodiesterase and a rapid reduction in guanosine cyclic 3',5'-phosphate concentration, phosphorylation of the 33K protein may be modulated by light in situ. In order to test this possibility, dark-adapted rat retinas were incubated for 30 min in the dark in phosphate-free Kreb's buffer containing [32P]orthophosphate. Following incubation, rod outer segments were detached by shaking, and the 32P-labeled rod outer segment proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, detected by autoradiography, and quantitated by densitometric scanning. The incorporation of radioactivity (32P) into the 33K protein was higher than into any other rod outer segment protein, and the amount of 32P-labeled 33K protein in the detached rod outer segments remained unchanged during 10 additional min of darkness. The addition of isobutylmethylxanthine to the incubation medium enhanced the incorporation of 32P into 33K protein to about 400% of the original level. Exposure of freshly detached rod outer segments to room light for 90 s decreased the amount of labeled 33K protein to 45% of its original level. The dephosphorylation of labeled 33K protein continued, reaching 12% of the original dark value 10 min after the previously illuminated sample was returned to darkness. Light initiated the phosphorylation of rhodopsin, and rhodopsin phosphorylation continued during the postillumination period of darkness.

1-Methyl-3-isobutylxanthine↗
PubMed1984

Prospective reimbursement and the diffusion of new technologies in hospitals.

This paper presents new evidence on the effects of prospective hospital reimbursement on the diffusion of new medical technologies in American hospitals. The probability, speed, and extent of adoption of five specific new technologies in six states, three with prospective reimbursement and three without, are examined using the results of a hospital survey conducted by the American Hospital Association for this study in 1980. The analysis demonstrates the influence of prospective reimbursement on the diffusion of new technologies. It is clear as well that these effects depend upon the specific attributes of the prospective reimbursement program and the characteristics of the technologies themselves.

Capital Expenditures↗
PubMed1984

Impact of adjuvant chemotherapy on cosmesis and complications in stages I and II carcinoma of the breast treated by biopsy and radiation therapy.

Cosmesis and complication rates were examined in patients with early stage carcinoma of the breast treated by biopsy and radiation therapy with and without adjuvant chemotherapy in an attempt to determine the effect of chemotherapy upon these parameters. Between April 1, 1975 and June 1, 1980, 51 patients were treated with radiation therapy and adjuvant chemotherapy (XRT + ACT) and 83 patients with radiotherapy alone (XRT). Chemotherapy usually consisted of cytoxan, methotrexate and 5-fluorouracil for 6 or 12 cycles. Minimum follow-up was 36 months. Cosmetic results deteriorated with time in both groups but to a greater extent in the XRT + ACT group. At 36 months, excellent cosmetic results were obtained in 73 of the 83 patients (88%) in the XRT group compared to 37 of 51 patients (73%) in the XRT + ACT group (p = less than .05). Comparison of the two treatment groups revealed that complication rates were significantly increased in the XRT + ACT group. Of the 51 patients in the XRT + ACT group, 21 patients (41%) suffered complications compared to 8 (10%) of the 83 patients in the XRT group (p = less than .001). This difference in complication rates resulted primarily from an increased incidence in the XRT + ACT group of wet desquamation in the electron beam portal used to treat the internal mammary lymph nodes and a trend towards a higher incidence of spontaneous nonpathologic rib fractures, myositis and arm edema. An increased incidence of nonbreast primary cancers was not seen. Our preliminary conclusions are that adjuvant chemotherapy has a negative impact upon cosmesis and complication rates in patients being treated with definitive radiotherapy. However, cosmetic results remain satisfactory and complication rates are maintained at an acceptable level. Continued close follow-up will be required before definitive conclusions can be reached as to the overall incidence and severity of the changes noted.

Adult↗
PubMed1984

Subsidizing the affluent: the case of medical education.

State and federal funds are important sources of revenue for medical schools, and a strong case can be made for public support for these institutions. Although the federal role is more widely known, the states in fact provide the bulk of direct support for medical training. The nature of aid from the two sources differs in significant ways. Most federal aid supports research or patient care, but much of state aid goes to support unconditional tuition subsidies. The primary beneficiaries of these subsidies are relatively affluent nonminority students who are beginning lucrative careers in the medical field--careers that would be lucrative even if no subsidies were provided. Nor does it appear that general subsidies are needed to attract poor and minority applicants. While targeted loans and scholarships to individuals may be justified, general tuition subsidies are not.

Education, Medical↗
PubMed1984

Outpatient adult inguinal hernia repair.

Repair of adult inguinal hernia has been done on an outpatient basis at our surgical facility for the past six years. In 616 consecutive repairs, complications have been remarkably few: one patient was electively admitted to hospital, two hernias have recurred and one patient needed to be catheterized. Patient acceptance has been enthusiastic.

Adolescent↗
PubMed1983

Biopsy and definitive radiation therapy in stages I and II carcinoma of the female breast.

One hundred-twenty patients with Stages I and II carcinoma of the female breast were treated by biopsy followed by definitive radiation therapy without mastectomy. The breast received 4500-5000 cGy (rad) using a 6 MV linear accelerator followed by a supplement to the area of the primary tumor of 2000 cGy (rad) using electrons in 99 patients (83%) and interstitial implantation in 21 patients (17%). Local recurrence was not recorded in the 43 patients with Stage I disease, while three of 77 patients (4%) with Stage II disease suffered a local recurrence. The actuarial five-year relapse-free survival was 91% and 60% in Stages I and II respectively. Cosmetic results were considered excellent by both physician and patient in the majority of cases. Axillary dissection was the recommended method of staging the axilla but was noted to be more morbid than axillary sampling. Electrons may be as effective as interstitial implantation as a means of supplementation following external beam therapy if specific guidelines are followed.

Actuarial Analysis↗
PubMed1983

A comparison of the predictions made by orthopaedic surgeons, nurses and physiotherapists about the rehabilitation problems of fracture patients.

Health service staff sometimes are not aware of the psychological and social aspects of patients' rehabilitation problems. This paper compares the accuracy of predictions made by orthopaedic surgeons, nurses and physiotherapists about the rehabilitation problems of a series of fracture patients. Predictions were obtained in the acute orthopaedic trauma wards of one hospital, from members of all three professions, about 26 patients selected as likely to have rehabilitation problems. Follow-up data were obtained from interviews with the patients during the six months after their injury and from the orthopaedic case notes. The orthopaedic surgeons accurately predicted 48 per cent of the problems that occurred, the nurses 26 per cent and the physiotherapists 20 per cent. In their predictions the surgeons discriminated more accurately than the nurses or physiotherapists between the occasions on which problems did and did not occur in the follow-up period. The surgeons were better predictors than the other professions about medical and orthopaedic, work and personal and social problems. Fifty-five per cent of the problems that occurred were predicted by members of one or more professions. If it is desired to base early decisions about treatment or referral in rehabilitation on predictions about patients' likely problems, there is a need to increase the proportion of problems that are accurately predicted, and to increase the ability of predictors to discriminate between the occasions on which problems are and are not likely to occur.

Disability Evaluation↗
PubMed1983

An internally referenced test strip immunoassay for morphine.

We describe an internally referenced immunochemical test-strip for use in the rapid detection of morphine. The method is based on the "enzyme-channelling" immunoassay technique, and a glucose oxidase-horseradish peroxidase enzyme pair is used to immunospecifically generate an insoluble, colored reaction product on the test-strip surface. Test strips are composed of two active surfaces, each of which contain co-immobilized glucose oxidase and antibody. The indicator pad contains antibody directed against the drug, and the color that develops on its surface is inhibited by the presence of drug in the sample. The reference pad contains anti-peroxidase and is used to set the assay detection limit and normalize for variations in temperature, timing, and sample interference. The 10-min assay protocol involves incubating the strip in sample, then incubating it in a developer solution containing glucose, a peroxidase chromogenic substrate, and a peroxidase conjugate of the analyte. The ratio of the color formed on the indicator pad to that formed on the reference pad is used to score the test as positive or negative for drug at a predetermined concentration.

Antibodies↗