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Biomedical subjects

T L Brown

Publications and source records attributed to T L Brown.

64 records · Page 4Linked to original sources
PubMed1981

Detection of alpha-amylase activity in unprocessed preamylase produced in the cell-free translation of porcine pancreatic RNA.

Preamylases, synthesized in the RNA-dependent rabbit reticulocyte lysate translation system supplemented with porcine pancreatic RNA were identified by their specific immunoprecipitation with anti-amylase. The preamylases have apparent Mr = 55,000 and 58,000 as compared to 52,000 and 55,000 for the purified, secreted alpha-amylase isozymes. In order to establish whether the unprocessed precursors may assume enzymatically active conformations, we have explored a highly sensitive activity gel electrophoresis technique, by which picogram quantities of enzyme can be detected. When standard alpha-amylase and translation products are subjected to electrophoresis on polyacrylamide gel containing 0.01% starch and CaCl2, active amylase which binds tightly to starch can only migrate as the starch is hydrolyzed. When the gel is subsequently stained with I2, the appearance of clear tracks, the lengths of which are roughly proportional to the logarithm of amylase concentration, signifies the presence of amylase activity. By this approach, we were able to detect amylase activity in a range corresponding to about 100 pg of pure amylase/10 microliters of translation mixture. This value agrees well with an estimate from radioactivity incorporation of total preamylase in the translation mixture, and we consequently conclude that unprocessed preamylase can assume the appropriate conformation to give enzymatic activity.

Amylases↗
PubMed1976

Ultrasound of the parotid gland.

Five cases of parotid gland masses were studied by ultrasound. Only retention cysts and true cysts of the parotid gland appear sonolucent at low and high gain settings. Benign and malignant tumor present as solid masses except for the Warthin's tumor which is sonolucent at lower gain settings but has a lattice of internal echoes at higher gain settings.

Adenolymphoma↗
PubMed1976

Ultrasound diagnosis of posttransplant renal lymphocele.

Two cases of posttransplant renal lymphoceles were diagnosed and followed by ultrasound. Lymphocele formation is a significant but often not thought of cause in a rejectionlike picture. Because of its noninvasive nature, ultrasound is an ideal method to detect and follow this complication.

Adolescent↗
PubMedDate not supplied

Sulphydryl modification inhibits taurine transport in human placental brush border membranes.

Taurine, 2-aminoethanesulphonic acid, is a -amino acid required for mammalian development. Although the human fetus accumulates taurine in many tissues, it has limited capacity for synthesis. The majority of fetal taurine is derived from the mother via placental transfer. The objective of this study was to analyse the functional groups involved in the taurine transport system of human placental brush-border membranes. Sulphydryl modifying reagents N-ethylmaleimide (NEM) and pyridyldithioethyl-amine (PDA) caused a dose-dependent inhibition of taurine uptake by brush-border membrane vesicles. Inhibition by PDA was reversible upon reduction by dithiothreitol but not by glutathione indicating that sulphydryl group(s) are located within the bilayer. Preincubation of brush-border membranes with taurine but not with taurocholate, before exposure to NEM, protected taurine transport function. Labelling studies using NEM and chemical cross-linking indicated that a 37.5 kDa protein was protected. These results demonstrate that sulphydryls located within the membrane bilayer are important for taurine transport in human placental brush-border membranes and suggest that a 37.5 kDa protein may be associated with Na(+)-dependent regulation of the taurine transporter.

Biological Transport↗
PubMedDate not supplied

Demographic and predictive correlates of smokeless tobacco use in elementary school children.

BACKGROUND: To assess the basic demographics and predictive correlates of smokeless tobacco use in school-age children, a stratified random sample of 559 rural and urban first, third, fifth, and seventh graders in western North Carolina was surveyed regarding experimentation with smokeless tobacco. METHODS: Two versions of a survey were developed: a shorter version administered orally to first graders and a longer version provided to others. Reported percentages across demographic variables were broken down in a 4 x 2 x 2 analysis of variance; correlations were used to assess the relationships among potentially predictive variables. RESULTS: Results indicated that 36 percent of male rural first graders had tried smokeless tobacco, increasing to 70 percent by the seventh grade. Overall, rural males were more likely to have tried or be regularly using smokeless tobacco than were urban males or females. Other questions correlating with smokeless tobacco use indicated that it is predicted by three general concerns: a) perceived flavor, b) self-concept and presentation to peers, and c) family influence. DISCUSSION: Educational interventions must begin at the kindergarten or first grade levels. Programs for adolescents must provide for alternative ways of receiving perceived social image benefits of smokeless tobacco use. Familial support must be considered in all programming.

Analysis of Variance↗