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Biomedical subjects

J Wolfe

Publications and source records attributed to J Wolfe.

At least 217 records · Page 12Linked to original sources
PubMed1977

Behaviourism.

Explore the source record for details and available documents.

Animals↗
PubMed1977

Induced alteration in uptake properties of Tetrahymena and its association with the development of mating competency.

The rate of uridine uptake in Tetrahymena declines by an order of magnitude by two hours after shiftdown to a non-nutrient buffer. This alteration in uptake properties cannot be accounted for by an increase in the intracellular pool of uridine, an increase in apparent Km for uptake or a decline in the rate in which uridine is processed intracellularly. It is argued that the decrease in uridine uptake is due to a reduction in numbers of functional transport molecules exposed at the cell surface and is a reflection of a developmentally related cell surface transformation. In addition, the putative decline in functional transport molecules cannot be entirely explained by metabolic turnover of these molecules in the absence of replacement, nor does it require the synthesis of new protein. We discuss the possibility that a shift in equilibrium between accessible and inaccessible transporters is operating. Finally, a close correlation between conditions which elicit the transport alteration and those which allow the development of mating competency suggests that the two phenomena may be coordinately regulated.

Animals↗
PubMed1977

A case of afferent loop obstruction secondary to recurrent carcinoma of the stomach with ultrasound and C.T. scan findings.

A case of afferent loop obstruction secondary to recurrent carcinoma of the stomach is reported. The patient presented in the early recurrence period with the clinical picture similar to that of pancreatic pseudocyst. This was the first reported case of afferent loop obstruction demonstrated by abdominal ultrasound and C.T. scan. The radiological distinguishing features and similarities of pancreatic pseudocyst and afferent loop obstruction are discussed. This case also shows a rarely reported manifestation of recurrent carcinoma of the stomach.

Female↗
PubMed1976

A cytological study of micronuclear elongation during conjugation in Tetrahymena.

Micronuclear elongation is the first major event in a series of nuclear changes occurring during the sexual stage of the life cycle of Tetrahymena. Beginning at about one hour after cells of complementary mating types have conjugated, the micronucleus leaves its recess in the macronucleus and swells slightly. This is accompanied by a reorganization of its chromatin from a reticular to a solid body. In the next stage the micronucleus assumes an egg shape, a development concomitant with the appearance of microtubules. While the chromatin "spins out" from the dense body, and microtubules increase in number, the nucleus assumes a spindle shape. During the elongation, which increases the length of the nucleus some fifty fold, microtubules are prominent in clusters just internal to the nuclear membrane, and parallel to the longitudinal axis of the nucleus. When elongation is completed the nucleus is curved around the macronucleus. Internally, partially condensed strands of chromatin are located off-center, towards the macronuclear side, and the density of the microtubules is diminished. At all the stages, DNA is located throughout the nucleus; neither discrete chromosomes nor synaptonemal complexes are seen. Occasionally cytoplasmic membrane systems are seen fused to the nuclear envelope which retains the typical appearance of a double membrane with pores.

Animals↗
PubMed1976

Desquamative interstitial pneumonia following long-term nitrofurantoin therapy.

Two patients with diffuse interstitial lung disease after long-term nitrofurantoin therapy were characterized clinically by exertional dyspnea and basilar rales, roentgenographically by diffuse interstitial infiltrate and physiologically by a restrictive lung defect. Pathologically, light microscopy revealed desquamative interstitial pneumonia. In one patient electron microscopy was characteristic of desquamative interstitial pneumonia. Immunofluorescent studies of one biopsy specimen showed specific fluorescence of interstitial cells with immunoglobulin E and third component of complement. In in vitro studies, nitrofurantoin therapy failed to induce lymphoblast transformation or histamine release. Treatment consisted of discontinuing the administration of nitro=furantoin and adding corticosteroids. Both patients felt better and showed clinical improvement. Our findings suggest that in some cases desquamative interstitial pneumonia may be drug related.

Adult↗
PubMed1975

Uridine uptake in a unicellular eukaryote during the interdivision period and after growth arrest.

The rate of uridine uptake was measured in Tetrahymena after shiftdown to non-nutrient physiological salt solution. Uptake follows Michaelis-Menten kinetics and an apparent Km of transport of 2 X 10-minus 6 M has been estimated. This value is in good agreement with those reported for tissue-derived cells in culture. Incorporation of uridine into RNA follows similar kinetics suggesting that uptake is rate limiting for incorporation. Within three hours after shiftdown the rate of uptake is decreased by an order of magnitude. Also at three hours after shiftdown pairing occurs between cells of complementary mating types. It seems likely that the change in uptake is a reflection of a surface change associated with differentiation. The rate of uptake was also measured during the interdivision period using cells synchronized by a physical selection procedure. A change in rate occurs at the time the cells begin replication of DNA and is essentially stable thereafter. These results indicate that there exists in Tetrahymena a relationship between surface properties as assayed by uridine uptake and properties of growth and differentiation.

Animals↗