Search PubMed⌕ Search

Biomedical subjects

L Fletcher

Publications and source records attributed to L Fletcher.

65 records · Page 4Linked to original sources

Inhibition of normal human granulopoiesis by neuroblastoma cells.

In vitro inhibition of marrow granulopoiesis was produced by a well-characterized human neuroblastoma cell line (CHP 134). A standard double layer, semi-solid agar system was employed in the experiments. The inhibition was present whether the neuroblastoma cells were mixed with the marrow cells or whether they were separated in a contiguous agar layer. Irradiation of the neuroblastoma cells lessened the inhibitory effect but did not eradicate it. Medium conditioned by the neuroblastoma cells had a mild, but not statistically significant, suppressive effect upon granulopoiesis. Additional studies to define the precise mechanism of suppression are underway.

Cell Division↗

Assay of thioinosinic acid, an active metabolite of azathioprine, in human lymphocytes.

1 A specific assay for the measurement of thioinosinic acid, in human lymphocytes, has been developed with a sensitivity of 50 ng of thioinosinic acid per 5 x 10(6) lymphocytes. 2 Thioinosinic acid is precipitated from purified lymphocytes as the lanthanum salt. Acid hydrolysis results in the formation of 6-mercaptopurine which, when converted into its phenyl mercury derivative, can be easily extracted into toluene. Back-extraction of the toluene layer with 0.1N HCl regenerates 6-mercaptopurine which is then assayed fluorometrically. 3 Blood samples were taken from renal transplant recipients 3 h after an oral dose of 50 mg azathioprine. The results from 5 patients gave a range of 54 to 173 ng of thioinosinic acid per 5 x 10(6) lymphocytes, with a mean of 110 ng. 4 In an in vitro incubation of azathioprine, 1mM with fresh human blood, 160 and 180 ng of thioinosinic acid per 5 x 10(6) lymphocytes was formed after 0.5 h and 5 h respectively. 5 The assay is suitable for the study of the kinetics of thioinosinic acid formation in lymphocytes of patients with kidney transplants. It could also prove useful in the study of thioinosinic acid formation in leukaemia patients undergoing 6-mercaptopurine treatment.

Azathioprine↗

Enolase isoenzymes. III. Chromatographic and immunological characteristics of rat brain enolase.

1. The chromatography of rat brain enolase (2-phospho-D-glycerate hydrolyase, EC 4.2.1.11) reveals three distinet components. One of these appears to be isoenzyme 1 (alpha alpha) but isoenzymes 2 (alpha beta) and 3 (beta beta) are absent. 2. The most acidic form of brain enolase was partially purified and an antiserum raised against it in the chicken. 3. a combination of chromatographic and immunological studies showed that a third type of subunit (gamma) is present in the brain giving rise to two further isoenzymes (alpha gamma and gamma gamma). 4. Developmental studies on the brain enzyme show an increase in total enolase activity from foetal life to maturity and a concurrent rise in the proportion of brain specific dimers. 5. It is therefore concluded that there are three genetic loci alpha, beta and gamma, coding for the enolase isoenzymes of rat tissues.

Aging↗

Shoplifting in bulimia nervosa.

This study compared the shoplifting patterns of 27 bulimic and 25 nonbulimic shoplifters. Bulimic shoplifters often stole food, but usually also stole other items. Nonbulimic shoplifters reported starting to steal at an earlier age, weighed more than bulimic shoplifters, and were more likely to endorse antisocial reasons for shoplifting.

Adolescent↗

Alcohol sales to pseudo-intoxicated bar patrons.

OBJECTIVES: Many establishments serve alcoholic beverages to obviously intoxicated patrons despite laws against such sales. To guide the development of interventions to reduce these illegal alcohol sales, this study used actors feigning intoxication to determine whether servers recognized obvious signs of intoxication and to assess the tactics servers used when dealing with intoxicated patrons. METHODS: Male actors ages 30 to 50 acted out signs of obvious intoxication as they attempted to purchase alcoholic beverages. If served during the first attempt, these pseudo-intoxicated buyers made second purchase attempts during the same visit. Observers accompanied the actors; after each visit, actors and observers recorded the servers' behavior and comments. RESULTS: Alcoholic beverages were served to actors portraying intoxicated patrons at 68% of first purchase attempts and 53% of second purchase attempts (62% of a total of 106 purchase attempts). The most common refusal technique was a direct refusal (68% of refusals), made with either no excuse or with reference to the actors' apparent intoxication level. Servers' second most commonly used refusal technique was offering alcohol-free beverages, such as coffee or water (18% of refusals). CONCLUSIONS: Further research is needed to determine why servers who recognize intoxication serve alcoholic beverages and what training, outlet policies, and external pressures are needed to reduce illegal alcohol sales to obviously intoxicated patrons.

Adult↗