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Biomedical subjects

R Feldman

Publications and source records attributed to R Feldman.

At least 163 records · Page 9Linked to original sources
PubMed1987

Diagnostic and operative arthroscopy of the ankle. An experimental approach.

To determine safe and effective placements of the arthroscope, 14 freshly amputated ankle joint specimens were used for experimental diagnostic and operative procedures. Preoperatively, chondral and osteochondral lesions, articular defects, and loose bodies were created within the ankle joint. The following arthroscopic portals were investigated: anteromedial, anterocentral, anterolateral, posteromedial, and posterolateral. Overlapping of vision fields was noted with the three anterior portals. Optimum visualization of a lesion was obtained when the arthroscope was placed on the same side as the lesion. Lesions on the posterior aspect of the talar dome and within the posterior talar pouch required the posterior placement of the arthroscope for optimum visualization. The use of the anterocentral approach, with a 2.7-mm arthroscope yields good visualization of the anterior aspect of the joint, and very often, of the posterior compartment. Anatomic guidelines for the avoidance of neurovascular structures and the exact placement of the arthroscope in both anterior and posterior portals are presented and were specifically defined in two additional fresh ankle specimens.

Ankle Joint↗
PubMed1986

Is there a competitive market for hospital services?

This paper focuses on the price elasticity of hospital-specific demand curves. Each hospital is assumed to practice price discrimination with respect to Medicare, Medicaid, and other patients. Among the third group, patients covered by Blue Cross are analyzed separately from those who pay their own bills or are covered by commercial insurance or a health maintenance organization (HMO). We use two different methods to estimate the price elasticity of demand. First, a pricing rule is developed from which hospital-specific price elasticities may be inferred. Second, the distribution of each payer's admissions at specific hospitals is examined to determine if low-priced hospitals attract more patients. Data for the analysis are taken from 31 hospitals in the Minneapolis-St. Paul metropolitan area in 1981. Results of the first analytic method indicate that hospitals had monopoly power in their markets for Blue Cross and self pay/commercial insurance/HMO patients. These results are confirmed and extended to Medicare patients by the hospital demand analysis.

Blue Cross Blue Shield Insurance Plans↗
PubMed1986

Intracranial arterial aneurysms in childhood: more recent considerations.

Nineteen children with congenital, mycotic, traumatic and tumoral arterial aneurysms were studied neuroradiologically. The important role of computed tomography (CT) was shown in two traumatic aneurysm cases where bleeding was clinically inapparent. Among the unique cases described was a boy with a pituitary tumor in whom an aneurysm was discovered incidentally; coexistence of these lesions in childhood has not been documented previously. Nor has a tumoral aneurysm been mentioned (the case reported had a surrounding primary anaplastic sarcoma). Rare cases included a cavernous carotid mycotic aneurysm and infants with hemorrhage from congenital distal middle cerebral artery aneurysms. Marked cellular responses within the aneurysm walls, believed to be a reaction to hemorrhage, were noted in both infants.

Adolescent↗
PubMed1986

The competitive impact of health maintenance organizations on hospital finances: an exploratory study.

In this study we explore whether HMO-induced competition has contained expenditures in Minneapolis/St. Paul hospitals. Specifically, we assessed the impact of HMOs on revenue, cost, and net income per admission in Twin Cities hospitals from 1979 to 1981. Some HMOs have obtained negotiated discounts from hospitals. We found that hospitals which gave larger discounts did not have lower costs per admission. This finding suggest that discounts do not force hospitals to operate more efficiently. In addition, hospitals with a large share of patients from HMOs or government Medicare and Medicaid programs did not have lower costs per admission than other hospitals during the years from 1979 to 1981. This finding casts doubt on the claim that discounts are justified by lower costs for HMO or government patients. Finally, neither HMO market share nor discounts had an adverse effect on hospital profits. During the three years studied, hospital profits in the Twin Cities showed an upward trend. This study concludes that if competition is to succeed it must encompass more than HMOs. HMOs may be important, but they are only one agent in the market. Thus, public policy created to induce competition must go beyond the simple stimulus of HMO growth.

Blue Cross Blue Shield Insurance Plans↗
PubMed1986

Regulation of hormone-stimulated cyclic AMP accumulation in intact human mononuclear leukocytes by blood plasma.

Several hormones, including catecholamines, histamine, and prostaglandin E1, regulate the function of human mononuclear leukocytes (MNL) by stimulating the accumulation of cAMP. Isoproterenol-stimulated cAMP accumulation in MNL isolated and washed at 4 degrees is five times greater than in cells prepared at ambient temperature. The current study was aimed at understanding this difference. cAMP accumulation in MNL prepared at ambient temperature could not be increased by chilling the cells for 4 hours. Warming MNL prepared at 4 degrees for 30 min, however, reduced later isoproterenol-, histamine-, and PGE1-stimulated cAMP accumulation by 65-85% without altering forskolin-stimulated cAMP accumulation and without altering cellular viability or ATP content. In broken cell preparations, there was no difference in either adenylate cyclase or phosphodiesterase activities, and no difference in the binding of isoproterenol to the beta-adrenergic receptors. The reduction in isoproterenol-stimulated cAMP accumulation in warmed intact cells was reversed when the MNL were incubated with autologous leukocyte-depleted blood or with plasma. These data suggest the presence of one or more factors in plasma that enhances hormone-stimulated adenylate cyclase activity in intact MNL.

Adenosine Triphosphate↗
PubMed1986

Effect of growth factors and methionine on glycolysis and methionine transport in rat fibroblasts and fibroblasts transfected with myc and ras genes.

The inhibition of glycolysis in tumor cells by methionine requires that the cells be incubated with methionine for several hours in the presence of serum. We now show that in the case of confluent rat-1 fibroblasts transfected with the ras gene the serum can be substituted by insulin and insulin-like growth factor I or II. No other growth factor tested was effective. In subconfluent ras cells additional growth factors (transferrin and high density lipoproteins) were required for maximal inhibition of glycolysis by methionine. Exploration of the mechanism of action of methionine revealed that the accumulation of [35S]methionine into rat-1 fibroblasts was only marginally increased by insulin. We propose that methionine inhibits an adenosine triphosphatase activity because addition of low concentrations of Nonidet P-40 greatly enhanced glycolysis even in the presence of methionine, suggesting that it did not affect the glycolytic enzymes directly. Methionine also affected growth both in monolayer and soft agar. Rat-1 fibroblasts transfected with the ras gene were markedly more sensitive to methionine than cells transfected with the myc gene.

Animals↗
PubMed1985

A comparative study of laser beam characteristics in blood and saline media.

Little information is available concerning the influences on laser radiation exerted by the various media through which lasing is done. The effects of saline solution and blood on argon laser beam divergence and projection were studied. In addition, the resulting effects on arterial tissue were evaluated after lasing through these media. This was performed with the fiber tip held in various positions relative to the arterial wall. The presence of blood, even in a diluted form, increased beam divergence and reduced forward projection. Perpendicular lasing through saline solution resulted in crater diameters similar in size to the core diameter of the fiber used irrespective of energy levels (424 +/- 97 microns at energy = 2 W X 5 seconds and 490 +/- 80 microns at energy = 2 W X 10 seconds). In contrast, lasing through blood produced much wider craters that increased in size with the higher energy level (878 +/- 215 microns at 2 W X 5 seconds and 1,294 +/- 314 microns at 2 W X 10 seconds). Arterial wall damage could also be inflicted at a greater distance when lasing through blood than through saline solution. Lasing arterial tissue through blood with the fiber tip held parallel to and in contact with the arterial wall resulted in wide craters when lasing was performed in a "static" as well as a "dynamic" fashion. Lasing through saline solution in these positions produced no visible damage to the arterial wall. These results provide some guidelines that may be useful in the clinical application of Argon laser revascularization.

Arteries↗
PubMed1985

Cost benefits of hemoccult screening for colorectal carcinoma.

Hemoccult screening for colorectal carcinoma was begun in 1979 at the Kaiser Permanente Medical Center, Oakland, California, as part of a program for periodic health examinations. A concomitant cost-benefit analysis was conducted to determine the long-term medical care costs and survival benefits of this procedure. Of 14,041 patients greater than or equal to 45 years of age mailed hemoccult slides, 10,255 (70.3%) returned them at the time of their examination. One hundred twelve (1.1%) were positive, and 12 colorectal carcinomas were detected. Additionally, 13 patients with one or more polyps greater than or equal to 1 cm and 45 patients with other gastrointestinal sources of blood were found. Of the screened cases of colorectal carcinoma, 50% were in Dukes' stage A compared with 25% found in this stage in our institution in 1974, when screening was not done. Five-year Dukes' stage-specific medical care costs and mortality rates were developed from the 1974 cases and were then applied to the screened cases of colorectal cancer. A savings in medical care costs of +14,685 and a projected increase of 22 years in life expectancy was found.

Aged↗
PubMed1985

A young man with a femoral hernia presenting as periumbilical pain.

The case of a 21-year-old man presenting with constant periumbilical pain is reported. The patient had a left groin mass which on palpation exacerbated his pain. The patient was taken to surgery where an incarcerated femoral hernia was repaired. A brief and uncomplicated postoperative course followed. The anatomy and clinical manifestations of femoral hernias are presented.

Adult↗
PubMed1985

Glycolysis and methylaminoisobutyrate uptake in rat-1 cells transfected with ras or myc oncogenes.

A high rate of aerobic glycolysis was catalyzed by rat-1 cells transfected with a ras oncogene (ras cells); rat-1 cells and rat-1 cells transfected with myc oncogene (myc cells) showed a low rate of glycolysis that was increased after exposure of the cells to type B transforming growth factor (TGF-beta). The uptake of radioactive methylaminoisobutyric acid or L-methionine via system A of amino acid transport also was accelerated after exposure of these cells to TGF-beta, with the myc cells being most sensitive and the ras cells least sensitive. Methionine was found to be a potent inhibitor of glycolysis in ras cells as well as in rat-1 or myc cells that were exposed to TGF-beta. We propose a relationship between the product of the ras oncogene (p21) and the protein(s) induced by exposure to TGF-beta.

Aminoisobutyric Acids↗
PubMed1985

Biased selection in Twin Cities health plans.

The data in Tables 1 through 4 show significant differences in the enrollment of higher health-related financial risk individuals and their families among health plans. FFS enrollees are older and exhibit more chronic illness on average. IPAs enroll a greater proportion of females than do PGP or FFS plans. PGPs and IPAs do not differ significantly in the age and chronic illness of their enrollees, but IPAs enroll a significantly greater proportion of females than do PGPs. The age difference between FFS and prepaid plans appears to be greater for long-term enrollees. The same pattern is true of chronic illness, but the results are often not statistically significant. We do not have time-series data, however, and cannot conclude that future comparisons among long-term enrollees will remains as they are now. In any care our data do not support the hypothesis that biased selection is a short-term problem that will be corrected as the population in prepaid plans ages. Our data contain a cross-section of environments for health plans in firms: long- and short-term offerings, long- and short-term enrollees, high and low out-of-pocket premium costs, etc. Our strongest results are the simplest: across all plans and environments there are significant differences in enrollee characteristics. These differences would not be inefficient if all groups paid actuarially fair premiums. However, mandatory offering and community-rating allow prepaid plans to enroll a younger population with less chronic illness and to maintain an information asymmetry that prevents employers and employees from determining--either prior to or following enrollment--the relationship of the prepaid plan's premium to its marginal cost.

Age Factors↗
PubMed1984

Subclavian venous stenosis. A complication of subclavian dialysis.

Subclavian hemodialysis catheters are widely employed for temporary hemodialysis access, but there are few reports of serious complications. We report three cases in which the prolonged (greater than 15 days) use of subclavian dialysis catheters ipsilateral to the permanent vascular access was associated with the development of subclavian vein (SCV) stenosis three to six months after the temporary catheter was removed. In one case, the use of the permanent access was severely limited by massive arm edema. We conclude that, in addition to the usual complications of SCV cannulation, long-term use of SCV hemodialysis catheters can be associated with major late obstructive complications that may compromise permanent vascular access. We recommend that, wherever possible, temporary dialysis catheters and other subclavian lines be placed contralateral to the permanent vascular access site in patients undergoing hemodialysis.

Aged↗
PubMed1984

Effect of the surface area of activated charcoal on theophylline clearance.

The effect of the surface area of activated charcoal on theophylline clearance was studied. Eight fasting, healthy men received intravenous infusions of either aminophylline (6 mg/kg, N = 3) or theophylline (5 mg/kg, N = 5) over 1 hour followed by either 5 Gm standard activated charcoal every 2 hours, 20 Gm every 2 hours, or 5 Gm PX-21 activated charcoal (with 3.6 times the surface area) every 2 hours. Theophylline t 1/2 and AUC with each regimen were respectively 6.3 +/- 0.5 (S.E.) hours and 88.9 +/- 8.4 mg/liter X hr with 5 Gm standard activated charcoal, 5.3 +/- 0.3 hours and 75.4 +/- 4.9 mg/liter X hr with 5 Gm PX-21, and 4.9 +/- 0.2 hours and 67.7 +/- 3.6 mg/liter X hr with 20 Gm standard activated charcoal. There was a relationship between the activated charcoal surface area and the reduction in theophylline t 1/2 and AUC. We conclude that the clearance of theophylline is related to the surface area of activated charcoal administered and that PX-21 may be a more potent activated charcoal product for enhancing theophylline removal.

Administration, Oral↗