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Biomedical subjects

W Cook

Publications and source records attributed to W Cook.

At least 19 recordsLinked to original sources
PubMed1997

Experimental infection of deer with bovine viral diarrhea virus.

In order to determine the susceptibility of deer to infection with bovine viral diarrhea virus (BVDV), four mule deer (Odocoileus hemionus) fawns and one white-tailed deer (O. virginianus) fawn were inoculated intranasally with the New York-1 strain of BVDV originally isolated from cattle. None of the animals developed clinical signs of illness. Virus was isolated from white blood cells from four fawns on one or more occasions from day 2 through day 15 post-inoculation (PI) indicating that infection and systemic spread of BVDV had occurred. In addition, virus was isolated from nasal swabs from three fawns, one to three times, from day 2 through day 8 PI. Four fawns had virus neutralizing antibody titers to two strains of BVDV prior to inoculation and all developed greater than four-fold increases in virus neutralizing antibody titers by 3 wk PI. No gross lesions of bovine viral diarrhea were detected at necropsy approximately 3 mo PI. A variety of nonspecific lesions were detected by histopathology. Based on these findings, mule and white-tailed deer are susceptible to infection with BVDV. Isolation of virus from nasal swabs is evidence that BVDV could be transmitted by deer via direct contact.

Animals↗
PubMed1995

Mouse thymus dendritic cells: kinetics of development and changes in surface markers during maturation.

The early thymus precursor population of adult mice has the capacity to generate T cells, B cells and dendritic cells (DC). These precursors were injected into the thymus of irradiated recipients in order to follow the kinetics of thymic DC development. The resultant cohort of T-lineage cells developing in the thymus was accompanied by a parallel cohort of DC, present at 10(3)-fold lower frequency. The intrathymic lifespan of these DC was as short as that of T-lineage thymocytes. As the thymic DC matured, some markers characteristic of the original precursor population gradually declined (Ly-5, c-kit, Sca-2) whereas markers characteristic of thymic DC appeared and were maintained (major histocompatibility complex class II, CD11c, NLDC-145 and CD8 alpha). Some thymic DC expressed the early B-cell marker BP-1, and BP-1 mRNA, throughout their maturation. The surface markers on thymic DC could be divided into two groups. Some markers, including class I and class II MHC, CD8 alpha and BP-1, appeared to be integral components of the DC surface. In contrast, other markers, including Thy-1, CD4 and CD8 beta, had probably been picked up from associated thymocytes.

Animals↗
PubMed1988

Mitogen plus interleukin 4 induction of C epsilon transcripts in B lymphoid cells.

To elucidate the mechanism of IL-4-induced enhancement of IgE and IgG1 production, murine splenic B cells and A-MuLV-transformed cells were cultured with LPS and IL-4 and assayed for epsilon and gamma 1 transcripts. Concomitant treatment with IL-4 and LPS induced expression of C epsilon transcripts in both normal and transformed cells. Expression of these truncated C epsilon transcripts preceded accumulation of normal epsilon mRNA in treated cells. Consistent data were obtained with respect to gamma 1 RNA expression. These results suggest that IL-4 can direct class switching in the context of a mechanism associated with differential expression of germline constant region genes.

Animals↗
PubMed1986

Alginate dental impression materials: chemistry, structure, and properties.

The setting behavior of calcium alginate impression materials was investigated by monitoring the viscosity, calcium ion activity, and shear modulus during the reaction. Structural information was also obtained from the dependence of viscosity and compressive modulus on the calcium concentration in model systems. The gelation time is primarily controlled by the concentration of Na4P2O7 in solution acting as a retarder, while the level and particle size of the alginate and CaSO4 X 2H2O also affect the kinetics through the dissolution rates and concentration effects. The Ca2+ crosslinks bridging the alginate chains in the network appear to be labile. Although this process of bond interchange and that of continued polymerization during deformation may be contributory mechanisms to permanent set, bond rupture appears to be the primary mechanism. Bond rupture can be reduced by increasing the alginate content in the system which also raises the tear energy. Both the permanent set and tear energy are affected by the filler particle morphology.

Alginates↗
PubMed1986

Decreased complement and bacteriostatic activities in the sera of cattle given single or multiple doses of aflatoxin.

Five steers given 1 dose of partially purified aflatoxin at concentrations sufficient to provide 0.2 mg to 0.8 mg of aflatoxin B1 equivalents/kg of body weight were compared with 4 steers given 14 daily doses of 0.25 mg of aflatoxin B1 equivalents/kg of body weight for complement activity and bacteriostasis. Complement activity was measured by hemolysis in gel, and bacteriostatic activity, by growth inhibition of Escherichia coli in liquid medium. In the single-dose group, complement activity and bacteriostatic activities decreased by 57 hours after dosing, and both returned to near base line by 168 hours. In the daily dose group, only bacteriostatic activity decreased, and the decrease persisted 2 weeks after the last dose of aflatoxin was given. Apparently, aflatoxin affects both complement-dependent and independent serum bacteriostatic activity.

Aflatoxins↗
PubMed1983

Effects of oral hydralazine on gas exchange in patients with cor pulmonale.

Vasodilators lower total pulmonary vascular resistance in some patients with pulmonary hypertension, but if vasodilators worsen arterial oxygenation in cor pulmonale, as they do in some patients with left ventricular failure, the benefits of a decrease in vascular resistance would be offset by a lack of change or a deterioration in systemic oxygen delivery. Measurement was made of arterial and mixed venous blood gases, minute ventilation, shunt fraction, alveolar-arterial oxygen difference, pulmonary arterial pressures, and cardiac output before and four hours after a single dose of hydralazine, 75 mg orally, in six patients (Group I) and before and after 48 hours of hydralazine, 50 to 75 mg orally, every six hours in 10 patients (Group II). Cardiac output increased 36 percent in Group I and 48 percent in Group II. In both groups total pulmonary vascular resistance decreased (8.0 +/- 2.8 to 6.1 +/- 2.6 units in Group I, p less than 0.01; 9.7 +/- 3.7 to 5.6 +/- 2.1 units in Group II, p less than 0.01). Arterial PO2 increased significantly both in Group I (61 +/- 8 to 67 +/- 10 torr, p less than 0.05) and Group II (50 +/- 13 to 54 +/- 13, p less than 0.05); however shunt fraction and alveolar-arterial oxygen difference were unchanged. The ratio of dead space to tidal volume decreased slightly in both groups, and minute ventilation increased significantly. Systemic oxygen delivery was increased by 39 and 51 percent in Groups I and II, respectively. Thus, gas exchange may be preserved or improved when hydralazine is used in the treatment of cor pulmonale.

Administration, Oral↗
PubMed1979

Regulation of carbohydrate metabolism in mouse liver. Effect of glucagon on gluconeogenic/glycolytic flux in isolated perfused livers.

1. Glucagon stimulated gluconeogenesis from both [U-14C]lactate and [14C]xylitol in isolated perfused mouse liver. 2. Addition of cyclic AMP also stimulated gluconeogenesis from [U-14C]lactate. 3. Glucagon caused a rapid (2.5 min) 12-fold increase in hepatic cyclic AMP but not cyclic GMP concentration. 4. Glucagon caused a rapid and stable decrease in hepatic fructose 1,6-diphosphatase activity measured in vitro. 5. The results are interpreted to indicate that glucagon stimulates hepatic gluconeogenesis in mice via cyclic AMP by two different mechanisms: (a) increased substrate uptake (i.e. utilization) and (b) increased gluconeogenic efficiency (i.e. inhibition of alternate substrate fates).

Animals↗
PubMed1974

Myxedema crisis.

Explore the source record for details and available documents.

Electrocardiography↗
PubMedDate not supplied

Alpha-melanocyte stimulating hormone facilitates learning of visual but not auditory discriminations.

The neuropeptide alpha-MSH has been proposed to influence learning and memory by increasing visual attention. To test the possibility that MSH selectively affects visual learning, rats were tested in learning tasks in which the cues were either visual or auditory. Maze and bar-press tasks were used. MSH administration increased the rate of learning of the visual tasks, regardless of the task difficulty or the type of response required of the rat. MSH had no effect on the rate of learning of the auditory tasks. These results support the hypothesis that MSH facilitates learning by influencing some aspect of visual information processing.

Acoustic Stimulation↗