Search PubMed⌕ Search

Biomedical subjects

R Bowers

Publications and source records attributed to R Bowers.

At least 37 records · Page 2Linked to original sources
PubMed1990

Kinetics of HIV-1 replication and intracellular accumulation of particles in HTLV-I-transformed cells.

The replication kinetics of HIV were examined in HTLV-I-transformed MT-2 cells. The duration of the initial replication cycle was 20 hours, determined by the first detection of infectious progeny virus, development of syncytia, and production of viral RNA and protein. A phase of exponential virus production followed until 62 h postinfection. Cell death occurred in the final phase of infection during which infectious virus production remained constant even though viral RNA and protein production increased at an exponential rate. Accumulations of HIV particles were observed within cytoplasmic vacuoles of infected MT-2 cells. Although cell lysates contained high titers of infectious virus, our data show that an increasing proportion of particles produced late in infection were not infectious.

Cell Line, Transformed↗
PubMed1984

Adaptation of canine saphenous veins to grafting. Correlation of contractility and contractile protein content.

Saphenous veins are used extensively to replace stenotic coronary arteries. However, the contractile and biochemical adaptations of grafted veins are unknown. The three purposes of this work were to characterize the contractile properties of grafted veins, to determine whether altered contractile characteristics were associated with quantitative changes in actin, myosin and collagen, and to determine which changes were associated with the surgical procedure and which with placement in the arterial circulation. Canine saphenous veins were removed and returned to their original location (venous autograft), while others were used to replace a segment of femoral artery (arterial graft). The grafts were removed 1, 4, and 8 weeks later and compared with the contralateral saphenous vein. Both graft types exhibited an increase in sensitivity to norepinephrine but not to potassium chloride. The venous autograft exhibited a reversible reduction in myosin content and in maximum contractile response (force/cross-sectional area) to potassium chloride and norepinephrine. In contrast, the arterial graft exhibited increased wall thickness and content of all measured proteins and decreased maximum contractile response. The latter occurred even though there was an increase in the net production of actin and myosin. Expressing the maximum contractile response in terms of the myosin content did not normalize the contractile response. These results suggest that, except for the elevated sensitivity to norepinephrine, the vein is capable of recovering from the effects of surgery within 8 weeks; however, placement of the vein in the arterial circulation delays this recovery and initiates a hypertrophic response that includes an attenuation of contractile function.

Adaptation, Physiological↗
PubMed1984

The location of middle mediastinal pheochromocytomas.

Eight middle mediastinal pheochromocytomas were located by means of 131I- meta- iodobenzylguanidine scintigraphy. The exact anatomic location of the lesions was confirmed by means of dynamic computed tomographic scanning following bolus injection of contrast medium. In all but one case the lesion had not been detected prior to scintigraphy despite extensive investigations including arteriography, venography with sampling, computed tomography with infusion of contrast medium, and in some cases surgical exploration of the abdomen and chest. Accurate anatomic location of the lesion permitted resection of five lesions from the cardiac atria and one from the aortopulmonary window. A sixth case in which an atrial pheochromocytoma was found by coronary angiography was not cured by resection of the primary tumor, and 131I- meta- iodobenzylguanidine scintigraphy revealed extensive metastases. Thus 131I- meta- iodobenzylguanidine scintigraphy has been of considerable value in the location of pheochromocytomas of the middle mediastinum, which may be a more frequent site than previously recognized.

3-Iodobenzylguanidine↗
PubMed1982

High pressure liquid chromatographic determination of mono- and disaccharides in presweetened cereals: Collaborative study.

A collaborative study was conducted using a modified AOAC method (sugars in chocolate) for the determination of fructose, glucose, sucrose, and maltose in presweetened cereals by high pressure liquid chromatography (HPLC). Eight samples consisting of 6 products were analyzed in duplicate by the HPLC method and the AOAC Lane-Eynon method. The AOAC method was modified to use water-alcohol (1 + 1) and Sep-Pak C18 cartridges for sample cleanup. The HPLC results indicate precision comparable to the lane-Eynon method and the chocolate method. The modified HPLC method has been adopted official first action.

Chromatography, High Pressure Liquid↗