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Biomedical subjects

S E Riley

Publications and source records attributed to S E Riley.

12 recordsLinked to original sources
PubMed2001

The Beat generation: a multigene family encoding IgSF proteins related to the Beat axon guidance molecule in Drosophila.

A previous genetic screen led to the identification of the beaten path (beat Ia) gene in Drosophila. Beat Ia contains two immunoglobulin (Ig) domains and appears to function as an anti-adhesive factor secreted by specific growth cones to promote axon defasciculation. We identify a family of 14 beat-like genes in Drosophila. In contrast to beat Ia, four novel Beat-family genes encode membrane-bound proteins. Moreover, mutations in each gene lead to much more subtle guidance phenotypes than observed in beat Ia. Genetic interactions between beat Ic and beat Ia reveal complementary functions. Our data suggest a model whereby Beat Ic (and perhaps other membrane-bound family members) functions in a pro-adhesive fashion to regulate fasciculation, while Beat Ia (the original secreted Beat) functions in an anti-adhesive fashion to regulate defasciculation.

Amino Acid Sequence↗
PubMed1998

Competency to stand trial adjudication: a comparison of female and male defendants.

Competency to stand trial adjudication is a decision point in the criminal justice system at which gender bias may result in different outcomes for female defendants as compared with males. However, this is an unexplored research area that lacks well-designed studies. The goals of this investigation, which used the largest known sample of U.S. female competency to stand trial defendants studied thus far, are to further understand this group of offenders and to address the gender bias issue as observed in a major southwestern urban court system. Multivariate logistic regression analyses on selected data for 157 female defendants and 187 of their male counterparts examined (1) variations within gender categories and (2) differences between men and women. The results of the within models showed some similarities, but also clear differences, in the determinants of court dispositions. The analyses failed to show an overall pattern of association between gender and competency adjudication. The influence of gender showed considerable variability across psychotic symptoms involving hallucinations and/or delusions: women with psychotic symptomatology were at high risk of being adjudicated incompetent. This study demonstrates how reliable data on female competency to stand trial defendants can assist the interface of the mental health and criminal justice systems in their adherence to the legal standard of competency. It also highlights the following research needs: (1) increased sample sizes of female evaluees; and (2) richer data sets with more and better information on how gender influences specific psychotic symptomatology, type of crime, and legally functional abilities.

Adult↗
PubMed1988

The mutagenic activity of gastric juice.

The mutagenic activity of fasting gastric juice was assessed in 123 patients including 18 with normal endoscopic findings, 53 peptic ulceration, 9 gastric cancer, 12 pernicious anaemia and 31 patients who had undergone peptic ulcer surgery in the past. Significant mutagenic activity was detected in 96 (78%). Marked variations in mutagenic activity were noted both within and between the patient groups and no significant differences were detected. No correlation was found between mutagenic activity and patient age or sex, gastric pH, bile acid concentrations or bacterial counts, intestinal metaplasia on gastric mucosal biopsy, or intragastric nitrite. About 30% of gastric juice samples showed evidence of a cytotoxic activity towards the Salmonella tester strains in the mutation assay. Preliminary studies on other body fluids showed the presence of significant mutagenic activity in fasting saliva, bile and plasma. These findings demonstrate widespread human exposure to potentially genotoxic substances.

Age Factors↗
PubMed1987

Effect of histamine H2-receptor antagonist therapy on the mutagenic activity of gastric juice.

There is concern at present that treatment with histamine H2-receptor antagonists might promote the development of gastric cancer by producing conditions which favour intragastric formation of N-nitroso compounds. If H2-receptor antagonist therapy causes increased intragastric levels of N-nitroso compounds, an issue not yet resolved by analytical studies, corresponding changes in the mutagenic activity of gastric juice might be anticipated. In this study mutagenic activity and pH were measured in fasting gastric aspirate from 18 peptic ulcer patients before and during the final week of therapy with ranitidine (n = 10) or cimetidine (n = 8). Mutagenic activity was assessed using Salmonella typhimurium TA98 and TA100 in a modified pre-incubation "fluctuation" test. No significant change in mutagenic activity was detected after therapy. Of 15 patients found to have significant mutagenic activity in their fasting gastric juice before treatment, 14 remained mutagenic following treatment. Mutation frequencies (sum of positive wells in duplicate 96-well microtitre plates, mean +/- SD) for TA98 and TA100 were respectively, 20 +/- 34 and 100 +/- 64 before compared with 10 +/- 6 and 102 +/- 65 after therapy (p greater than 0.05). Changes in mutagenic activity were similar in both treatment groups and unrelated to duration of therapy, changes in gastric pH or ulcer healing. In vitro, neither cimetidine in aqueous solution, nor gastric juice preincubated with cimetidine showed significant mutagenic activity. These results provide no evidence that increased intragastric levels of genotoxic chemicals, such as N-nitroso compounds, occur during H2-receptor antagonist therapy.

Adult↗
PubMed1985

Effect of increased intake of vitamin C on the mutagenic activity of gastric juice and intragastric concentrations of ascorbic acid.

Mutagenic activity, ascorbic acid levels and pH were measured in fasting gastric juice from eight patients given oral supplements of vitamin C (1 g qid X 7 days). Supplementation significantly reduced mutagenic activity and increased intragastric ascorbate levels without altering gastric pH. These results demonstrate for the first time the relation between intragastric ascorbate levels, mutagenic activity and oral supplements of vitamin C. The findings are discussed in relation to the possible chemoprevention of gastric cancer.

Adult↗
PubMed1984

Effect of storage at 4 degrees on prepared Salmonella/microsome test plates.

Salmonella/microsome soft-agar overlay ('Ames' test) plates were prepared using the previously published 'York' method. Plates treated with either added 3-methylcholanthrene (3MC) or 3,3'-dichlorobenzidine (DCB) and Aroclor-induced rat-liver S9 were stored at 4 degrees after preparation and removed at time intervals thereafter for incubation at 37 degrees. The number of 3MC-induced mutants in TA100 fell within 24 h of storage by 50% but then remained at this level until 96 h. Storage for a total of 336 h still showed some residual mono-oxygenase activity. On the other hand the ability to convert DCB to a mutagen for TA98 appeared to increase with storage, reaching a peak by 96 h. After this time the number of induced mutants fell until by 336 h the numbers were approximately equal to those plates which had not been stored in the cold.

3,3'-Dichlorobenzidine↗
PubMed1984

Mutagenicity of gastric juice: the importance of controlling histidine concentration when using Salmonella tester strains.

The mutagenic activity of gastric juice has been assessed using bacterial tester strains that undergo reverse mutation (Salmonella typhimurium:his(-)----his(+)). Free histidine, a known source of inaccuracy in this mutation test system, was detected in 42 of 73 juice samples (concentration range 3.5-992.4 micrograms/ml); high histidine concentrations were significantly correlated with hypochlorhydria. The effect of histidine was controlled by using a pre-incubation modification of the Salmonella fluctuation test in which juice samples and their corresponding control cultures containing equivalent amounts of histidine were incubated with the tester bacteria prior to plating out. Significant mutagenic activity was found in a high proportion of samples (18 of 20). The histidine content in gastric juice which can affect in vitro mutagenicity testing must be adequately controlled before positive or negative results can be equated with the presence or absence of intragastric carcinogens.

Adult↗
PubMed1978

Long-term storage of tissue samples for cell culture.

The establishment of cultured cell lines from skin biopsies stored at -196 degrees C for periods up to 1 year has been investigated. Attempts to initiate cell cultures from the frozen tissue samples were uniformly successful. There was no alteration in chromosome constitution, morphological appearance, or specific activities of lysosomal enzymes in cells cultured from the stored samples. This process can safeguard against failure of the initial tissue culture and provide an alternate means of storing viable cells when it is impossible or impractical to initiate a cell culture immediately.

Cell Division↗
PubMed1976

Effect of nutritional status on rat adipose tissue, muscle and post-heparin plasma clearing factor lipase activities: their relationship to triglyceride fatty acid uptake by fat-cells and to plasma insulin concentrations.

1. In rats in a variety of nutritional states, the adipose tissue clearing factor lipase activity is strongly, positively correlated with fat-cell triglyceride fatty acid uptake. 2. In the same animals, muscle clearing factor lipase activity is inversely correlated with the activity of the enzyme in adipose tissue and with the plasma insulin concentration. 3. In starved animals that are given glucose, adipose tissue clearing factor lipase activity is positively correlated with the plasma insulin concentration. 4. The effect of changes in nutritional status on the activity of clearing factor lipase in rat post-heparin plasma depends on the heparin dosage used. The administration of glucose, but not of fructose or sucrose, to starved rats alters the response to heparin injection towards that found in rats in the fed state.

Adipose Tissue↗
PubMed1974

Effects of fructose, sucrose and glucose feeding on plasma insulin concentrations and on adipose-tissue clearing-factor lipase activity in the rat.

The rise in adipose-tissue clearing-factor lipase activity that results from feeding glucose to starved rats cannot be duplicated by giving equicaloric amounts of fructose or sucrose. An inability of the administered fructose and sucrose to raise the plasma insulin concentration probably accounts for this failure in enzyme response.

Adipose Tissue↗