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Biomedical subjects

K B Taylor

Publications and source records attributed to K B Taylor.

At least 55 records · Page 3Linked to original sources
PubMed1980

Activity and kinetic properties of basal aryl hydrocarbon hydroxylase during proliferation in the transformable C3H 10T1/2 CL8 cell line.

Basal aryl hydrocarbon hydroxylase (AHH) activity and its kinetic properties were studied as a function of proliferation in C3H mouse embryo 10T1/2 CL8 cells. Activity was low in freshly plated cells, increased during exponential growth, peaked at confluency, and then declined. The apparent Km-values for benzo[a]pyrene (BP) and NADPH were less in proliferating (approx. 0.37 microM BP, 3.3 nM NADPH) than in confluent cells (0.74-1.39 microM BP, 33.4-53.4 nM NADPH). Cells at different growth states responded differently to benz[a]anthracene (BA) and aminophylline, an inhibitor of cyclic nucleotide phosphodiesterases. When cells were harvested at the mid log phase of growth, 12 h of exposure to aminophylline caused maximum induction, while 24 h of BA treatment were required. In contrast, at early confluence, 12 h of BA treatment gave the greatest levels of activity, while exposure to aminophylline did not induce AHH. In fact, decreases in activity were observed. These differences are indicative of different regulatory mechanisms for BA and aminophylline induction. They also suggest the regulation of basal AHH by cyclic nucleotides changes during growth. The exposure times giving maximum activity were used to determine the kinetic properties of BA-induced activity. As with basal AHH, the Km-value for BP was less in log phase (0.2-0.4 microM BP) than in confluent cells (0.64-1.05 microM BP). Moreover, the Km-values for BP and NADPH in control cultures at confluency (0.10-0.14 microM BP, 15.4-23.2 nM NADPH) were less than those for BA-treated cells (0.64 microM BP, 37.9-54.8 nM NADPH) under the same nutritional conditions. The finding that the Km-values for BP is lower in rapidly dividing cells than in confluent cells may help to explain why proliferating cells are more susceptible to transforming agents.

Animals↗
PubMed1980

The effect of variations in vitamin C intake on the cellular immune response of guinea pigs.

The uptake of tritiated thymidine by isolated peripheral blood lymphocytes obtained from male guinea pigs immunized with bovine serum albumin was studied in animals maintained on various amounts of Vitamin C for 28 days. Animals were pair-fed on ascorbate-free diet and were supplemented intraperitoneally with 0, 25, or 250 mg Na-ascorbate per day. Scorbutic animals lost weight rapidly during the final 2 experimental weeks. Their daily food intake averaged only 4 g/day during the last week; thus, pair-fed ascorbate-supplemented groups were also subjected to acute nutritional stress. Lymphocytes from guinea pigs receiving 250 mg Na-ascorbate per day incorporated in vitro the highest amounts of tritiated thymidine both in the absence of nonspecific mitogen and in the presence of concanavalin A or phytohemagglutinin. Responses to lipopolysaccharide were not conclusive. Total circulating white cells counts and relative numbers of T and B lymphocytes were assessed in a second study made under identical constraints. In scorbutic animals the percentage of B lymphocytes increased and that of T lymphocytes decreased continuously over the 4-week period. The opposite effect was observed in vitamin C-supplemented animals. These studies suggest that very high doses of ascorbate support elevated mitotic activity after 4 weeks of much reduced food intake.

Animals↗
PubMed1980

Inhibition of parietal cell function by human gammaglobulin containing gastric parietal cell antibodies.

Parietal cell antibodies (PCA) are found in up to 90% of sera from pernicious anaemia patients but it is often stated that they could represent an epiphenomenon without being directly responsible for the achlorhydria. In the present studies a direct effect of these antibodies on the secretory function of gastric acid-secreting cells has been demonstrated in two different experimental systems. In one set of experiments IgGs containing PCA activity were shown to inhibit acid secretion specifically in the living gastric mucosa of the bull frog suspended as a diaphragm between two chambers. The other system demonstrated their inhibition of carbonic anhydrase activity in a cytochemical bioassay for human G17-gastrin, suggesting a blocking effect on the gastrin receptors in the canalicular microvilli or the cell membrane. These experiments suggest a direct pathogenic role for PCA in autoimmune fundal gastritis and in pernicious anaemia.

Anemia, Pernicious↗
PubMed1979

Cell-mediated cytotoxicity and humoral immune response in ascorbic acid-deficient guinea pigs.

Guinea pigs were divided into three dietary groups: ascorbic-acid deficient, pair-fed, and ad libitum control. Two weeks later guinea pigs were immunized intradermally with 5 x 10(8) chicken erythrocytes in Freund's complete adjuvant. Hemagglutinating antibody titers to chicken erythrocytes 2 weeks after immunization were comparable in all three dietary groups. In vitro 51Cr release from labeled chicken erythrocyte target cells incubated with lymphoid cells from spleens of ascorbic acid-deficient guinea pigs was significantly less than with spleen cells from pair-fed and ad libitum control guinea pigs. The percentage of splenic lymphoid cells that formed rosettes with rabbit erythrocytes, a T cell marker, was the same in all three dietary groups. The defect of ascorbic acid deficiency may reflect an impairment of T lymphocytes function in cell-mediated cytotoxicity or a change in number or function of another cell type.

Animals↗
PubMed1979

Epidemic gastritis with hypochlorhydria.

Seventeen of 37 healthy volunteers participating in studies of acid secretion and 1 patient with Zollinger-Ellison syndrome became rapidly and profoundly hypochlorhydric. A mild illness with epigastric pain occurred in 9 subjects, usually several days before detection of hypochlorhydria. Gastric mucosal biopsy specimens taken from subjects during hypochlorhydria revealed severe fundal and antral gastritis; however, even when acid secretion was severely depressed, parietal cells were abundant and appeared normal histologically. During hypochlorhydria, gastric permeability to hydrogen, sodium, and lithium was normal in 4 subjects. Serum gastrin concentrations were usually normal, whereas serum pepsinogen concentrations were invariably elevated. Serum parietal cell antibodies were not present. Acid secretion returned to near baseline levels in 14 of 17 subjects after a mean of 126 days (range 53--235); severity of gastritis diminished concurrently in 7 of 10 subjects on whom biopsies were serially performed. An infectious etiology is suspected, although serologic studies and bacterial and conventional viral cultures of stool and gastric juice have not identified a candidate agent.

Achlorhydria↗
PubMed1977

HLA antigens in Addisonian pernicious anaemia: absence of a HLA and disease association.

An examination of HLA antigens in 72 unrelated Caucasian subjects with pernicious anaemia (PA) has revealed no significant association of any HLA-A or B genes with the disease. These data do not confirm the previous reports in the literature which had suggested an increased frequency of the B7 and/or A3 antigen among patients. In addition, the study of four families, each with two or more PA patients, does not support close linkage between disease susceptibility or autoantibody formation and the HLA locus. These data suggest that genes in or near the HLA region may not significantly affect susceptibility to PA.

Anemia, Pernicious↗
PubMed1976

Isotope effects in the binding of NADH to equine liver alcohol dehydrogenase.

The isotope effect upon the binding constant of NADH to equine liver alcohol dehydrogenase is determined with a method in which the isotopic ratio is measured concurrently in the free and the bond form of the coenzyme, by use of a propellent-pressurized ultrafiltration apparatus for separation of the two. The value for KH/KD for the binding constants was 1.00 +/- 0.02 at pH 10.3 and 25 degrees C.

Alcohol Oxidoreductases↗
PubMed1976

Gastric morphology and serum gastrin levels in pernicious anaemia.

Mucosal biopsies from multiple sites in the stomachs of 21 patients with pernicious anaemia have been examined. The histological changes almost always involved the entire gastric mucosa, including that of the pyloric antrum. Metaplastic changes were almost universal and consisted of intestinal metaplasia in the body and antrum and pyloric metaplasia in the body. The severity of the pyloric metaplasia was such as to make the distinction between body and antrum on biopsy impossible. No relationship was found between serum gastrin activity and the histological appearances of the gastric antrum or body.

Adult↗
PubMed1976

Gastritis duodenitis, and circulating levels of gastrin in duodenal ulcer before and after vagotomy.

Biopsy specimens have been taken from five standard sites in the stomach and from the duodenal bulb in order to investigate the association of gastritis and duodenitis with duodenal ulcer. Twenty patients with chronic duodenal ulcer were investigated in this manner and in addition had gastric secretion tests and a radio-immune assay of serum gastrin under differing conditions. The patients were then treated either by a truncal vagotomy and pyloroplasty (TVP) or by a highly selective vagotomy without a drainage procedure (HSV). All the investigations were repeated three months postoperatively. Duodenal ulcer was usually associated with gastriitis, although this varied in extent and severity from patient to patient. In nearly all the patients, gastritis was present at the pyloric end of the stomach and along the lesser curve. In more than half of the patients, gastritis was also present in the body of the stomach but the fundus was usually spared. Chronic duodenitis was found in the duodenal bulb in all these patients. After vagotomy there was a marked increase in both the extent and severity of the proximal gastritis in both treatment groups but the distal gastritis remain almost unchanged. There was little change in the incidence of duodenitis after vagotomy but its severity was lessened. No correlation was found between the peak acid output (PAO) in response to Histalog and the severity of the gastritis or the duodenitis either before or after operation, with one exception. The postoperative PAO was significantly less in those patients who developed a severe proximal gastritis after vagotomy. No relationship was found between the severity of the distal gastritis and the levels of serum gastrin. No correlation was found between either the basal or peak acid output and the corresponding serum gastrin levels before or after vagotomy.

Biopsy↗
PubMed1975

Isolation of parietal cells from guinea-pig gastric mucosa and the immunological characterization of their antigenic structure.

A method is described for the isolation of parietal cells from the gastric mucosa of the guinea pig by enzymatic digestion with collagenase. A suspension was obtained that contained 70-80% parietal cells. About 80% of the cells were viable immediately after incubation, but viability dropped sharply after one hour. Parietal cells were identified by their morphology on light and electron microscopy, by their uptake of neutral red, by immunofluorescent staining and by carbonic anhydrase activity. Antibodies to four distinct parietal-cell antigens were obtained from rabbits immunized with the isolated parietal cells or fractions thereof. These antibodies were directed against the microsomal fraction of the parietal-cell cytoplasm, the plasma and nuclear membranes, the soluble proteins, and Castle's intrinsic factor. The antibody against the microsomal fraction, though reacting in the same way as the antibody to parietal cell canaliculi found in the serum of patients with pernicious anaemia, showed greater species specificity.

Anemia, Pernicious↗