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Biomedical subjects

C Davis

Publications and source records attributed to C Davis.

At least 343 records · Page 19Linked to original sources
PubMed1984

Characteristics of three new avian sarcoma viruses, ASV 9, ASV 17, and ASV 25.

Three new avian sarcoma viruses, ASV 9, ASV 17, and ASV 25, were isolated from spontaneous tumors. They transform chicken embryo fibroblasts but not hemopoietic cells and induce fibrosarcomas in young chicks. All three viruses belong to the envelope subgroup A and cannot replicate without a helper virus, because they lack the pol and most, if not all, of the env gene. ASV 9 and ASV 17 have a genome of 5.0 kb; the genome of ASV 25 is 6.0 kb. The following onc sequences were tested for homology to the genomes of the three new avian sarcoma viruses: src, fps, yes, myc, myb, erbA, and erbB. These tests were negative except for erbB which showed faint hybridization with the genome of ASV 25. ASV 9 codes for a prominent 130-kdalton gag-linked transformation-specific protein. ASV 17 and ASV 25 transformed cells appear to contain multiple gag-linked transformation-specific proteins that still require further study.

Animals↗
PubMed1984

Rehabilitation social workers: measuring their ability to predict discharge destination of rehabilitation patients.

Most rehabilitation centers only admit patients for rehabilitation who have a reasonable chance of being discharged to a noninstitutional setting. With certain classifications, such as stroke, 20 to 30% of patients are often discharged to a skilled nursing facility (SNF). Problems associated with rehabilitation admission procedures make careful psychosocial determinations difficult. We attempted to have experienced rehabilitation social workers predict discharge placement following a formal evaluation. Three experienced rehabilitation social workers met formally with patients and/or families for an initial interview following admission to the rehabilitation unit. They assessed the functional goals developed by the rehabilitation team and predicted which patients would go home and which would go to a SNF. Their predictions were compared to the actual discharge placement. A chi square test revealed that the social workers accurately predicted discharge home but were unable to accurately predict which patients would go to an SNF. Of those predicted to return home, 95% did so. Of those predicted to go to an SNF, only 57% did so. Of the total sample of 126 patients, 86% were discharged home and 14% were discharged to an SNF. This finding suggests that patients should not be denied a trial of rehabilitation solely on the basis of projected discharge placement.

Aftercare↗
PubMed1983

The adverse consequences of heavy Trichuris infection.

Sixty-seven children with heavy Trichuris trichiura infection (Group A) were compared to 73 control children of similar socio-economic status but with light or no T. trichiura (Group B), for nutritional status, rates of concomitant bacterial and protozoal, and symptoms and clinical signs associated with heavy T. trichiura infection. Anoscopy was used to determine heavy T. trichiura infection. Measurements and physical examination were done on Group A on admission to and discharge from hospital; 46% were seen on follow-up visit two to eight months later. Children in Group B were seen only once. There were significant differences for nutritional status (p less than 0.01) and rates of bacterial and protozoal co-infection (p less than 0.01) and a significantly greater rate of invasive amoebiasis in Group A. After treatment, nutritional parameters of Group A children improved significantly, symptoms and clinical signs decreased and there was also a significant decrease in the rate of concomitant bacterial and protozoal infection. Subgroups of Group A children, with and without concomitant enteropathogens, revealed that infection with Entamoeba histolytica and bacterial enteropathogens had had no significant impact on clinical and nutritional status.

Amebiasis↗
PubMed1983

Effects of NaCl on the uptake of alpha-[14C]aminoisobutyric acid by the halotolerant bacterium Halomonas elongata.

The alpha-aminoisobutyric acid (AIB) transport system of the halotolerant bacterium, Halomonas elongata, was examined. Cells were grown in L-alanine defined medium with 0.05, 0.375, 1.37, 2.5, or 3.4 M NaCl. Each group of cells was resuspended in buffered salts with different NaCl concentrations (0.05, 0.375, 1.37, 2.5, and 3.4 M) and the uptake of alpha-[14C]AIB was measured. Optimum AIB uptake occurred in the 0.375 M NaCl solution for the lower salt grown cells and the 1.37 M NaCl solution for the higher salt grown cells. When cells were grown in the higher salt media and suspended in hypoosmotic solutions, appreciable AIB uptake occurred; but for cells grown in lower salt media and suspended in hyperosmotic solutions, the uptake was dramatically reduced. This effect was mainly attributed to cell plasmolysis which in turn resulted in some cell death. The AIB uptake was Na+ specific and this analogue was not metabolized after being transported into the cells. An amino acid competition study gave a pattern similar to that of a marine bacterium.

Amino Acids↗
PubMed1983

Studies of the mechanism of passive anaphylaxis in human airway smooth muscle.

This investigation was carried out to study allergic contraction of passively sensitized human airway smooth muscle in response to specific antigen challenge. We attempted to determine the role played by histamine, slow reaction substances (SRSs), and cyclooxygenase products in the mediation of this response in tracheal smooth muscle. Tissues were passively sensitized with serum from ragweed-sensitive patients (15 h, 4 degrees C). Subsequent challenge with ragweed antigen produced a slowly developing contraction. The peak contraction to a dose producing a maximal response was 37 +/- 6% of the carbachol maximum. Mepyramine (5 X 10(-6) M) did not alter the contraction. Methylprednisolone (2 X 10(-5) M) attenuated the response to antigen but had no significant effect on the contractile response to arachidonic acid. Indomethacin (5.6-28 X 10(-6) M) enhanced the peak antigen-induced contractions by 25 +/- 11% whereas 5,8,11,14-eicosatetraynoic acid (6.4 X 10(-5) M) selectively attenuated the antigen-induced contraction by 86 +/- 12%. Nordihydroguarietic acid (6-12 X 10(-6) M) attenuated both the antigen plus arachidonate induced responses. FPL-55712 (1-2 X 10(-6) M) antagonized the contractions to antigen. Compound 48/80 and goat antihuman immunoglobulin E produced similar slowly developing contractions in sensitized and in some nonsensitized tissues. These responses, except for an early component of the response to 48/80, were independent of histamine and were reversed by FPL-55712. These findings suggest that arachidonic acid metabolites mediate (slow reacting substances) and modulate (prostaglandins) allergic contraction of human airway smooth muscle while any histamine released contributes little or nothing to the contraction in the larger airways.

Anaphylaxis↗
PubMed1983

Roasting and braising beef roasts in microwave ovens.

Cooking time, yield, and palatability of beef round, chuck, and rib eye roasts cooked in microwave ovens and in conventional ovens were compared. Cooking times were considerably shorter in the microwave ovens than in the conventional ovens. Reduced power was used for microwave cooking of roasts, except that rib eye roasts were cooked at full power for the first 5 min. The yield of cooked lean meat was the same for round and chuck roasts cooked by either type of oven, while the yield was lower for rib eye roasts cooked in the microwave oven than for rib eye roasts cooked in conventional ovens. Tenderness, softness, and natural flavor panel ratings and tenderness as measured by shear force were not affected by the treatment. Rib eye roasts were browner and less juicy when cooked in the microwave ovens.

Animals↗
PubMed1983

Protofilament number in microtubules in cells of two parasitic nematodes.

The parasitic nematodes, Ascaridia galli and Trichostrongylus colubriformis, were prepared for electron microscopy with fixatives containing tannic acid, which allowed their microtubule protofilament number to be examined. In contrast to many mammalian tissues, the nematodes did not contain microtubules with 13 protofilaments. Ascaridia galli contained microtubules with 11 protofilaments in all tissues examined, including nerve, intestinal, pharyngeal, and hypodermal cells. Trichostrongylus colubriformis contained nerve cells, known as microtubule cells, with bundles of larger microtubules (approximately 30 nm in diameter) with 14 protofilaments. The microtubules in these cells did not appear to be continuous for the entire length of the axon. Other cells examined in T. colubriformis, including nerve, intestinal and pharyngeal cells, contained two distinct types of microtubules, one with 11 protofilaments and an approximate diameter of 25 nm, and one with 12 protofilaments and an approximate diameter of 27 nm. All cell types examined contained both types of microtubules.

Animals↗
PubMed1982

Controlled trial of dexamethasone and mannitol for the cerebral oedema of fulminant hepatic failure.

A controlled trial of 44 patients was undertaken to evaluate the use of dexamethasone (32 mg stat, 8 mg qds) in preventing, and intravenous mannitol (1 g/kg) in reversing the cerebral oedema of fulminant hepatic failure. Diagnosis of cerebral oedema was based on intracranial pressure recordings or the presence of defined clinical signs. Cerebral oedema developed in 34 patients with similar frequency in those treated with and without dexamethasone (16 of 21 and 18 of 23 respectively). In those 34 patients episodes of cerebral oedema resolved significantly more frequently in the 17 patients who received mannitol than in the 17 patients who did not (44 of 53 and 16 of 17 respectively, p less than 0.001). Dexamethasone did not affect survival but among patients who developed cerebral oedema those who received mannitol had a significantly better survival than those who did not receive it (47.1% and 5.9% respectively, p 0.008, Fisher's one-tail test).

Adolescent↗
PubMed1982

Pharmacological study of the contractile activity of leukotriene C4 and D4 on isolated human airway smooth muscle.

Synthetic leukotriene C4(LTC4) and leukotriene D4(LTD4) were examined on isolated human tracheal and bronchial smooth muscle. Both LTC4 and LTD4 produced slowly developing contraction of trachealis and bronchus which were submaximal (70-85% of the carbachol maximum) and were not blocked by 1.0 microM atropine, 5.0 microM mepyramine, or 5.6 microM indomethacin. The EC50's for LTC4 and LTD4 were 10.3 and 1.8 nM on trachealis and 1.8 and 1.7 nM on bronchus, respectively. LTD4 was in excess of 20 000 times more potent than acetylcholine on some bronchial and tracheal tissues. Similar differences in potency were obtained in some tissues when LTC4 and LTD4 were compared with histamine. Tissues pretreated for 30 min with 2.0-4.0 microM FPL-55712 were less reactive to LTC4 and LTD4 than untreated control tissues. Established contractions to LTC4 and LTD4 persisted despite washing with fresh Krebs solution, were partially reversed by FPL-55712 (0.5-10 microM) and the Ca2+ channel blocker D-600 (5-10 microM), but were completely reversed by the catecholamine adrenaline (1.0 microM) and by high concentrations of FPL-55712 (greater than 20 microM). The marked potency of the leukotrienes on human tracheal and bronchial smooth muscle suggests an important role for these lipoxygenase products in respiratory disease.

Bronchi↗
PubMed1982

Control of human airway smooth muscle: in vitro studies.

An in vitro study of neural and myogenic control of human tracheal smooth muscle was undertaken. Over 80% of these had active tension and 13% had phasic contractile activity. Tonic and phasic activities were not reversed by indomethacin, 5,8,11,14-eicosatetraynoic acid, methysergide, mepyramine, atropine, or tetrodotoxin (TTX) but were blocked by the calcium antagonist verapamil. In some quiescent strips, tonic and/or phasic activity was induced by exposure to potassium-conductance blockers such as 4-aminopyridine (4-AP) and tetraethylammonium chloride (TEA). Electrical (field) stimulation resulted in frequency-dependent biphasic responses: an initial atropine-sensitive cholinergic contraction followed by a nonadrenergic relaxation. This biphasic response to low stimulus parameters (less than 0.5 ms, less than 15 Hz) was blocked by TTX and scorpion venom and enhanced by 4-AP and TEA, consistent with a neural mechanism. Relaxation responses to longer pulse durations (0.5-1 ms) were not blocked by TTX despite abolition of contraction nor were they enhanced by 4-AP and TEA, suggesting a nonneural mechanism. ATP, adenosine, arachidonate metabolites, histamine, 5-hydroxytryptamine, neurotensin, or vasoactive intestinal polypeptide were ruled out as possible nonadrenergic mediators. The nature and physiological significance of the nonneural inhibitory response remains unknown.

4-Aminopyridine↗