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Biomedical subjects

R Feldman

Publications and source records attributed to R Feldman.

At least 199 records · Page 11Linked to original sources
PubMed1980

Detecting unsuspected thyroid dysfunction by the free thyroxine index.

The free thyroxine index (FTI) was used in 2,704 adults to detect unsuspected thyroid dysfunction. Among 2,581 adults found to be clinically euthyroid without thyroid medication, 2,571 had a truly normal FTI (121 to 360) and ten had a falsely abnormal FTI (seven less than 121, three greater than 360). Among 25 subjects with newly diagnosed thyroid dysfunction, there were eight hyperthyroid (prevalence, 0.31%) and 14 hypothyroid (prevalence, 0.50%) subjects. The sensitivity of the FTI was 1.0, and the specificity was 0.996. The predictive value of an abnormal FTI with a prevalence of 0.81% was 67%. The cost to find a new case averaged $127. The annual incidence of symptomatic hyperthyroidism was 0.05%; of hypothyroidism, about 0.08%. We conclude that the FTI is cost-effective for case finding in thyroid dysfunction.

Aged↗
PubMed1980

Influence of selenium on vascularization in the hamster cheek pouch.

The inhibitory effect of selenium (Na2SeO3) on the vascularization induced by amelanotic tumor implants (A Mel-4B32) n the Syrian hamster cheek pouch membrane is reported. Among control animals receiving A Mel-4B32 implants, 19 developed tumors out of 19 chambers with capillary proliferation being observed on day 4 after implant. Addition of 50 microgram Se to the chamber at the time of tumor implant delayed the initial observation of capillary proliferation until day 10 after implant. In the 50 microgram Se treated group, tumor-induced vascularization developed in 11 of 15 chamber implants and not in the remaining 4. Intermediate doses of 5 and 10 microgram Se added to the chamber at the time of tumor implant delayed the initial observation of capillary proliferation to days 7 and 9, respectively, with tumors developing in all chambers. Neither sodium nor sulfite altered the vascular pattern. Capillary proliferation was observed on day 4 after tumor implant when either 50 microgram NaCl or 50 microgram S as Na2SO3 were added to the chamber at the time of implant. Provision of Se as a drinking water supplement also delayed the onset of capillary proliferation.

Animals↗
PubMed1979

Reinvestigation of the reaction of chymotrypsin with N-furylacryloyltryptophan derivatives at acidic pH.

The reaction of alpha-chymotrypsin with N alpha-3-(2-furyl)acryloyl-L-tryptophan methyl ester (FA-Trp-OMe) and amide has been investigated in aqueous and dimethylsulphoxide cryosolvent solutions from pH2 to 7 and over a wide temperature range. Previous reports have suggested that an intermediate preceding the acyl-enzyme can be detected spectrophotometrically in the reaction with methyl esters of FA-Trp and FA-Tyr at low pH [Yu & Viswanatha (1969) Eur. J. Biochem. 11, 347--352), and that this intermediate is an oxazolinone [Coletti-Previero et al. (1970) FEBS Lett. 11, 213--217]. We show that the previous interpretations of the time-dependent spectral changes were incorrect, and that the only detected intermediate is the acyl-enzyme. This may be isolated by gel filtration at pH less than 2.5, 1 degree C, owing to its relative stability. The pH-dependence of the rates of acylation and deacylation from pH 8.5 to 2.0 are consistent with a single ionization of pK congruent to 7.0 in both aqueous and cryosolvent solutions.

Chemical Phenomena↗
PubMed1978

Rocky Mountain spotted fever and jaundice. Two consecutive cases acquired in Florida and a review of the literature on this complication.

Rocky mountain spotted fever is increasing in Florida, a state that has had few cases in the past. The typical clinical illness has been well described, but jaundice has been rarely reported. In two patients with illnesses resembling leptospirosis, jaundice appeared on the sixth and ninth day of illness, and peak bilirubin levels were between 7 and 9 mg/100 ml. Liver biopsy specimen from one patient showed a nonspecific hepatitis. Hemolysis and renal dysfunction may have contributed to the production of jaundice in these patients. Fourteen instances of jaundice were reported in 43 autopsied cases as of 1941, but since that time only rare mention of jaundice has been made.

Child↗
PubMed1978

Two-to-one A-V block with four-to-three A-V nodal wenckebach, a form of spontaneous multilevel block.

Electrophysiologic studies in one patient with spontaneous 2:1 atrioventricular block and variable PR intervals revealed two sites of conduction block. Typical 4:3 A-V nodal Wenckebach was present in addition to Mobitz type II infra-His block. The HV of conducted complexes was 120 msec and the shortest recorded AH interval was 250 msec. When 2:1 A-V block with fixed PR interval was present, only 2:1 Mobitz type II infra His-block was present. The mechanism of this example of spontaneous multilevel A-V block is discussed and compared to other previously reported cases.

Aged↗
PubMed1978

The microcirculation in two transplantable melanomas of the hamster. I. In vivo observations in transparent chambers.

Twenty-eight transparent chambers were inserted into the cheek pouches of hamsters and daily serial observations made of the changing vasculature of transplants of 2 varieties (A-Mel-4B32, ZGYP1) of amelanotic melanomas. The tumor A-Mel-4B32 grew at a rate which covered 50% of the viewing area in 3--4 days, while the tumor ZGYP1 covered less than 10% of the viewing area at this time and did not cover 50% of the viewing area until 9.5 days after transplantation. The difference in growth rate was not reflected in any differences in the morphology of the vascular network and distribution of the venous arcades.

Animals↗
PubMed1978

The microcirculation in two transplantable melanomas of the hamster. II. Scanning electron microscopy.

Normal and tumor vessels observed in vivo on the hamster cheek pouch membrane in transparent chambers were examined by scanning electron microscopy. Large, thin walled veins were found in the reactive zone around the 2 amelanotic melanomas of the hamster. Sinusoidal vessels and channels contained red cells, which did not possess any vascular wall, were seen in the main substance of the tumors. In this system all the vessels within the central mass of the tumor transplant comprise newly formed vessels. The surfaces of the tumor cells and the lining of the tumor vessels were examined by this technique. The biological history i.e., age of the vessel and location from the growing edge of the tumor, were known. The surface of the tumor cells on cut section differed in appearance from the areolar tissue of the pouch membrane. Scanning electron microscopy of the inner aspect of newly formed tumor vessels permits much greater sampling of the tissue than transmission electron microscopy and further work should reveal aspects of the interaction of the blood with tumor stroma.

Animals↗
PubMed1978

Metastasis via the blood stream: the method of intravasation of tumor cells in a transplantable melanoma of the hamster.

Tumor cells entered the vascular compartment of transplantable amelanotic melanoma of the hasmster 3 days after transplantation, closely following vascularization of the transplant. Examination of the tortuous giant capillaries at the edge of the transplant showed tumor cells breaching the thin endothelium of these vessels. Extravasation of red cells into the surrounding tumor tissue and attempted haemostasis by small platelet aggregates attached to the vessel walls were also found.

Animals↗
PubMed1978

The financial viability of rural primary health care centers.

Primary health care centers have been proposed to meet the health care needs of rural America. Some centers become financially "self-sufficient", receiving their entire budgets from direct patient or third-party payments; others shut down when external funding is withdrawn. An explanation for this difference is important, because funding agencies may not wish to subsidize centers whose financial futures appear bleak. This study identifies the correlates of financial self-sufficiency. A survey conducted in late 1976 or 164 rural clinics provided 101 usable responses. Multiple regression analysis of the data shows that the longer a center has been in operation, the more self-sufficient it will become. Hospital control of the center and provision of laboratory tests increase self-sufficiency; outreach services and nonprofit status reduce it. Two variables related to financial self-sufficiency are separately examined. Clinics with a faster growth rate of patient visits are more self-sufficient, and smaller clinics tend to grow faster. More self-sufficient clinics experience less difficulty in keeping professional staff. The presence of a state Area Health Education Center (AHEC) program also eases the problem of staff retention.

Ambulatory Care Facilities↗
PubMed1978

The effects of advertising--lessons from optometry.

We examine the effect of advertising bans on the price of optometric examinations. Advertising is viewed as an information medium which enables consumers to search for lower prices, to the relative disadvantage of high-cost, low-volume sellers. Self-interest leads these sellers to support bans on advertising. An empirical section shows that price is 16 percent higher in states that ban optometric and optician price advertising, when examination length, procedures, and office equipment are held constant. The two advertising bans work by interaction--both must be present to raise significantly the price of eye examinations.

Advertising↗
PubMed1977

Effect of metabolic alkalosis on respiratory function in patients with chronic obstructive lung disease.

Eleven instances of a mixed acid-base disorder consisting of chronic respiratory acidosis and metabolic alkalosis were recognized in eight patients with chronic obstructive lung disease and carbon dioxide retention. Correction of the metabolic alkalosis led to substantial improvement in blood gas values and clinical symptoms. Patients with mixed chronic respiratory acidosis and metabolic alkalosis constitute a common subgroup of patients with chronic obstructive lung disease and carbon dioxide retention; these patients benefit from correction of the metabolic alkalosis.

Acetazolamide↗
PubMed1977

Serum glucose levels and alcohol-consumption habits in a large population.

Using information from approximately 100,000 multiphasic check-ups performed in these facilities, we have found an association between alcohol-drinking habits and serum glucose values one hour after an oral challenge with 75 gm. of glucose. There was a positive dose-response relation between reported alcohol intake and serum glucose level over the most common range of alcohol intake. Serum glucose levels were highest in the group who consumed six to eight alcoholic drinks per day. However, among those who said they took nine or more drinks per day, mean serum glucose levels were significantly lower than in the six-to-eight-drink group. These relations persisted when the analysis was controlled for the effects of age, sex, race, adiposity, time since last food intake, time of day, previously known diabetes, and previously known liver disease. A search of the literature failed to uncover a complete explanation for these phenomena.

Age Factors↗