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Biomedical subjects

M J Lewis

Publications and source records attributed to M J Lewis.

At least 289 records · Page 16Linked to original sources
PubMed1979

Drugs and human memory: effects of low doses of nitrazepam and hyoscine on retention.

1 The effects of diazepam (5 mg) and hyoscine hydrobromide (0.3 mg) were assessed in two memory tasks: short-term retention of digit strings and the free recall of items from categorizable lists. 2 One hundred and two healthy subjects were tested in an independent-groups design. Subjects were assigned randomly to either placebo, diazepam or hyoscine groups. Treatments were administered orally under double-blind conditions. 3 The short-term retention of digits was impaired to an equivalent degree and locus for both drugs (P less than 0.05). This effect was ascribed to the action on primary memory. 4 The drugs produced no significant effects on the recall of categorizable lists either in terms of the number of words recalled or the cohesiveness of categorical recall. 5 These results demonstrate that drugs of different pharmacological actions produce isomorphic psychological deficits in memory and that 'anti-memory' effects on one task should not be extrapolated to all aspects of memory.

Female↗
PubMed1978

beta-Endorphin is associated with overeating in genetically obese mice (ob/ob) and rats (fa/fa).

Small doses of the opiate antagonist naloxone selectively abolished overeating in genetically obese mice (ob/ob) and rats (fa/fa). Elevated concentrations of the naturally occurring opiate beta-endorphin were found in the pituitaries of both obese species and in the blood plasma of the obese rats. Brain levels of beta-endorphin and Leu-enkephalin were unchanged. These data suggest that excess pituitary beta-endorphin may play a role in the development of the overeating and obesity syndrome.

Animals↗
PubMed1978

Giant-cell pneumonia caused by measles and methotrexate in childhood leukaemia in remission.

Four children who had acurate lymphoblastic leukaemia in remission and developed pneumonia were studied. Investigations including electron microscopy and immunofluorescence of lung biopsy material disclosed measles, although there was no clinical evidence of the disease. Despite an identical presentation, two types of illness developed: two children died of giant-cell pneumonia, while the other two developed pneumonia indistinguishable from that associated with methotrexate treatment, recovering when treated with steroids and gammaglobulin. Measles infection is easily overlooked in the absence of rash. The diagnosis may be suggested by clinical and radiological features and confirmed by specific immunofluorescence staining of lung biopsy tissue.

Child↗
PubMed1978

The effects of low doses of diazepam on human performance in group administered tasks.

1. The effects of diazepam in 5 mg dosage were assessed on a range of psychological tasks. Seventy-eight healthy subjects were tested in an independent groups design; subjects were randomly assigned to either control, placebo or drug group. Treatments were administered orally under double blind conditions. 2. Auditory vigilance performance was unimpaired, in terms of (a) correct detections, (b) false alarms or (c) the subjects' estimates of the duration of the task. 3. The short term retention of digit strings was impaired by diazepam (P less than 0.05), especially for those digits presented in the middle of the sequence. 4. Searching for a few letters among many was significantly impaired by diazepam (P less than 0.01). 5. Diaepam had no effect on performance at a mental arithmetic task; neither was there a placebo effect. 6. Results were discussed in the light of the characteristics of drug sensitive tasks. It was concluded that characteristics such as feedback of results, monotony, and memory load are more likely to be drug sensitive when in combination than in isolation.

Attention↗
PubMed1978

Effects of delta1-trans-tetrahydrocannabinol on mechanical performance of isolated heart muscle preparations.

1 The effects of four concentrations of delta1-trans-tetrahydrocannabinol (delta1-THC) (0.1, 1, 5 and 20 microgram/ml) were compared to that of the vehicle (ethanol, 0.5 microliter/ml) on the mechanical performance of isolated cardiac muscle of the cat and rat. 2 In rat isolated papillary muscles, delta1-THC (20 microgram/ml) caused a decline in mechanical performance (-8% in developed tension and -11% in Vmax) in contrast to the apparent lack of effect of ethanol. 3 All other parameters of mechanical performance studied in both rat and cat papillary muscles were unaffected by delta1-THC when compared with ethanol. 4 It was concluded that delta1-THC in concentrations up to 20 microgram/ml had negligible effect on contractile performance, the time course of contraction or muscle elasticity in rat and cat isolated papillary muscle preparations under the conditions studied.

Animals↗
PubMed1978

Obstetrics: education and practice in Sydney, 1870-1939: part 1.

The development of obstetric education in Sydney, 1870-1939. is presented in two parts: part 1 looks at the education of nurses and part 2 looks at the education of doctors and their practice of midwifery. Maternal mortality remained stubbornly high until the late 1930's. Reformers urged better education as the solution to the "problem" of maternal mortality. It is suggested that the established maternity care system very probably limited such benefits as came from better education.

Australia↗
PubMed1978

Simple method for the isolation of astaxanthin from the basidiomycetous yeast Phaffia rhodozyma.

A method is described for the quantitative and, possibly, large-scale extraction of astaxanthin from the yeast Phaffia rhodozyma. The method utilizes extracellular enzymes produced by the bacterium Bacillus circulans WL-12, which partially digests the yeast cell wall and renders the carotenoid pigments extractable by acetone or ethanol. Complete recovery of astaxanthin from heat-killed P. rhodozyma cells was obtained after growing B. circulans WL-12 on these yeast cells for 26 h and then extracting the yeast-bacterium mixture with acetone. A bacteria-free lytic system, which gave quantitative extraction of astaxanthin from P. rhodozyma, was obtained by concentrating the culture broth from the growth of B. circulans WL-12 on P. rhodozyma cells. Hydrolytic enzyme activities detected in this concentrate included beta-(1 leads to 3)-glucanase, beta-(1 leads to 6)-glucanase, alpha-(1 leads to 3)-glucanase, xylanase, and chitinase. The lytic system was found to work most efficiently at pH 6.5 and with low concentrations of yeast.

Bacillus↗
PubMed1978

Isolation and identification of the cytoplasmic membrane from Saccharomyces carlsbergensis by radioactive labeling.

The cytoplasmic membrane of Saccharomyces carlsbergensis was isolated by enzymatic digestion of the yeast cell wall, followed by lysis of the protoplasts and fractionation by ultracentrifugation in a discontinuous sucrose density gradient. Location of the cytoplasmic membrane fraction on the sucrose gradient was made by labeling intact protoplasts with [G-3H]dansyl chloride, and was settled at the 50% (wt/vol) sucrose gradient (d = 1.186 g/cm3). Approximately 80% of the radioactivity was found in the membrane fraction prepared in the presence of Mg2+ ions. However, when protease inhibitors were used in the preparation step, the membrane fraction contained over 90% of the total radioactivity. The presence of Mg2+ ions during membrane isolation and purification enhanced the aggregation of membrane components but, at higher concentrations, as well as in the prolonged presence of Mg2+ ions in the membrane suspension, it caused the breakdown of membrane components. The membrane preparation contained Mg2+-adenosine triphosphatase, which was insensitive to oligomycin and ouabain. The distribution of Mg2+-adenosine triphosphatase in different fractions during sucrose gradient is reported.

Adenosine Triphosphatases↗
PubMed1978

Controlled clinical study of naltrexone side effects comparing first-day doses and maintenance regimens.

In a controlled double-blind clinical study, 42 patients reported side effects and severity of side effects to naltrexone on three different first-day doses and maintenance dosage regimens. Initiating doses of 25, 100, and 150 mg were administered. The maintenance regimens involved 350 mg of naltrexone per week for 4 weeks with drug administration in Group A, five times weekly; in Group B, three times weekly; and in Group C, twice weekly. All three groups received identical doses for the last dosage administered each week. The first-day doses produced no significant quantitative difference in side effects. Overall, the three groups reported little difference in side effects. Nonetheless, the regimen with the least number of patients reporting side effects daily was that of Group B. In no case, regardless of dose or dosage regimen, did any patient have side effects of such a nature as to require termination of their participation in the study.

Administration, Oral↗
PubMed1977

The uptake and overflow of radiolabelled beta-adrenoceptor blocking agents by the isolated vas deferens of the rat.

1. A comparison of uptake into and overflow from the isolated vas deferens of the rat has been made between [3H]-noradrenaline ([3H]-NA), [14C]-D-sorbitol and three radio-labelled beta-adrenoceptor blocking agents, [14C]-practolol, [14C]-(+/-)-propranolol and [3H]-penbutolol. 2. The accumulation of [3H]-NA after 30 min incubation was reduced by desmethylimipramine (DMI) 1 X 10(-8)M and was also reduced in vasa from rats pretreated with 6-hydroxydopamine (6-OHDA). This was not so with [14C]-D-sorbitol. 3. 6-OHDA pretreatment of the rats reduced the uptake of [3H]-penbutolol after 30 min incubation but not that of [4C]-propranolol or [14C]-practolol. DMI 1 X 10(-8)M did not alter the tissue uptake of [14C]-propranolol, [14C]-practolol or [3H]-penbutolol. 4. Electrical stimulation of vasa preloaded with [3H]-NA caused a significantly greater increase in [3H]-NA overflow than during the resting, unstimulated periods. No such increase in overflow was observed with [14C]-sorbitol or any of the three beta-adrenoceptor blocking agents use. 5. The beta-adrenoceptor blocking agent penbutolol was shown to possess adrenergic neurone blocking activity in the isolated vas deferens of the rat. 6. It is concluded that any effect that practolol or (+/-)-propranolol have on noradrenergic neurones is brought about without the need for these drugs to gain access to the interior of the neurone.

Adrenergic beta-Antagonists↗