Detection of somatic mutations in man: evaluation of the microtitre cloning assay for T-lymphocytes

A method of detecting 6-thioguanine-resistant lymphocytes bythe cloning of T-lymphocytes in microtitre wells is evaluatedfor its usefulness in population monitoring. Factors shown toaffect the cloning efficiency of lymphocytes include the strainand irradiation level of the lymphoblastoid feeder cells andthe use of a pre-incubation period in bulk culture without mitogenicstimulus before plating at limiting dilutions. Cord blood sampleshave markedly lower mutant frequencies than adult blood samples.The adult range was 8.0 x 10^–7 to 1.8 x 10^–5. Sevenmales and seven females aged between 23 and 47 years were sampled.No effect of sex or age was found. Individual samples whichwere divided at collection and treated separately did not varyfrom each other, but repeat samples taken at different timesshowd up to a 2-fold variation. The application of this methodin population monitoring is discussed.     

Vitamin B12 and folate status in acute geropsychiatric inpatients: affective and cognitive characteristics of a vitamin nondeficient population

This chart review study examined the serum vitamin B12 and folate status of 102 geriatric patients newly admitted to a private psychiatric hospital. Only 3.7% were B12 deficient and 1.3% were folate deficient; 4% were anemic. Nevertheless, those with below-median values of both vitamins had significantly lower Mini-Mental State scores than patients higher in one or both vitamins. Patients with "organic psychosis" with a negative family history for psychiatric disorder had significantly lower B12 levels than those with a positive family history. In major depression, folate levels correlated negatively with age at onset of psychiatric illness and length of hospitalization. These data suggest that (1) biochemically interrelated vitamins such as B12 and folate may exert both a separate and a concomitant influence on affect and cognition; (2) poorer vitamin status may contribute to certain geropsychiatric disorders that begin at a later age and lack a familial predisposition.     

An ethological analysis of the effects of chlordiazepoxide and bretazenil (Ro 16-6028) in the murine elevated plus-maze

The effects of chlordiazepoxide (2.5-15.0mg/kg), a full benzodiazepine receptor agonist, and bretazenil (5.0-30.0mg/kg), a partial benzodiazepine receptor agonist, were examined in the murine elevated plus-maze paradigm. Behaviours recorded comprised the traditional indices of anxiety as well as a number of ethologically derived measures. Results show that chlordiazepoxide (10-15mg/kg) and bretazenil (5-30mg/kg) not only decreased traditional indices of anxiety but also reduced risk assessment behaviours such as head-dipping and stretch attend postures from secure areas of the maze. Both compounds produced these effects without adversely affecting general activity levels. While traditional indices of anxiety did not clearly discriminate between the two compounds, some differences were apparent on the ethological measures. The dose-response curves for bretazenil were generally shallower than those for chlordiazepoxide, confirming its partial agonist profile. Together, these data support the view that benzodiazepine receptor partial agonists may have utility in the management of human anxiety disorders.     

The influence of stimulus parameters on the visual field indices by automated projection perimetry

The various stimulus parameters offered by two standard automated projection perimeters [Humphrey Field Analyser 630 (HFA) and Octopus 2011, namely, stimulus size and location and the interaction of adaptation level and stimulus duration, were compared in a sample of 20 patients attending a glaucoma clinic using the visual field indices mean defect (MD), loss variance (LV), short-term fluctuation (SF) and corrected loss variance (CLV). LV and SF were greater with Octopus program 32 compared with Octopus program G1 (P < 0.02). No difference in the indices was found between stimulus sizes I and III for HFA program 30-2. MD was greater for program 30-2 compared with program 32 (P < 0.002) when expressed in terms of log (L/L) whereas LV (P < 0.02) and SF (P < 0.02) were greater for program 32. All differences were considered to be negligible in the clinical sense.