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Biomedical subjects

M A Taylor

Publications and source records attributed to M A Taylor.

At least 163 records · Page 9Linked to original sources
PubMed1987

Influence of selenium deficiency on glutathione disulfide metabolism in isolated perfused rat heart.

Selenium deficiency causes a fall in rat cardiac glutathione peroxidase activity. As a consequence, isolated perfused selenium-deficient heart does not release increased amounts of GSSG when hydroperoxide is infused. However, the total amount of glutathione measured as intracellular GSH, intracellular GSSG and GSSG released from the heart when hydroperoxide is infused does not equal the total glutathione measured in these pools in untreated hearts (Xia, Y., Hill, K.E. and Burk, R.F. (1985) J. Nutr. 115, 733-742). GSSG can react with protein sulfhydryl groups to form glutathione-protein mixed disulfides (PrS-SG). PrS-SG were measured in perfused selenium-deficient and control hearts infused with t-butylhydroperoxide and were found to account for the previously unmeasured glutathione. The ability of the selenium-deficient heart to transport GSSG was also examined. GSSG was produced non-enzymatically by infusing diamide. The diamide-treated selenium-deficient heart formed GSSG and released it at the same rate as similarly-treated control heart. Thus although selenium deficiency decreases GSSG formation by glutathione peroxidase, it does not affect cardiac GSSG transport.

Animals↗
PubMed1987

The immunohistochemical location of cathepsin L in rabbit skeletal muscle. Evidence for a fibre type dependent distribution.

The immunohistochemical location of cathepsin L in rabbit soleus, plantaris and psoas muscles was investigated using the peroxidase-anti-peroxidase (PAP) technique. The amount of enzyme detected varied according to the fibre type, which were identified by histochemical staining of serial sections for succinate dehydrogenase and alkali-stable myosin ATPase. In the three muscles studied labelling was strongest in the highly oxidative fibres and weaker in the other fibre types with least staining in the fast white fibres. Immunoreactive cathepsin L appeared to be most concentrated at the periphery of muscle fibres, especially near to the nuclei, although some staining was seen throughout the fibres.

Adenosine Triphosphatases↗
PubMed1987

Induction of maturation in small Xenopus laevis oocytes.

The competence of Xenopus laevis oocytes in various stages of growth to respond to progesterone treatment was investigated. Full-grown (stage 6) oocytes undergo nuclear membrane dissolution and resume meiosis in response to progesterone exposure, while smaller oocytes (stages 3-5; less than 1100 micron in diameter) do not. The defect which prevents 750- to 1050-micron oocytes from responding to progesterone can be overcome by microinjecting cytoplasm withdrawn from a stage 6 oocyte. Germinal vesicle breakdown in these small oocytes occurs on a timetable similar to that of stage 6 oocytes exposed to progesterone and is accompanied by a twofold increase in protein synthesis as well as the activation of MPF. The results argue that a cytoplasmic factor(s) which probably first appears at late stage 5 is required for progesterone responsiveness. The identity and role of the factor(s) in the development of maturation competence and the regulation of maternal mRNA translation are discussed.

Animals↗
PubMed1987

Accumulation of free amino acids in growing Xenopus laevis oocytes.

The sizes of amino acid pools in growing Xenopus laevis oocytes have been measured. The total free amino acid content per oocyte increases nearly 25-fold during oocyte growth. Together, glutamic acid and aspartic acid account for approximately 59-75% of the total amino acid pool in Xenopus oocytes. On the other hand, methionine and cysteine are the least abundant of the amino acids detected, each accounting for less than 0.7% of the total pool in developing oocytes. It is argued that the acid-extractable amino acid pool represents the precursor pool used in protein synthesis.

Amino Acids↗
PubMed1987

The nature of emotional blunting: a factor-analytic study.

To investigate the components of emotional blunting, we factor-analyzed an emotional blunting scale, and examined the relationships between the derived factors and several clinical variables in two patient samples. Two factors were identified, corresponding to "lack of emotional expression" and "avolition". The "avolition" factor was strongly related to clinical improvement after treatment. Discriminant analyses indicated that schizophrenics could be differentiated from manics by emotional expression and from depressives by avolition. Scores on two shorter scales derived from the factors were also highly predictive of clinical improvement and diagnosis. These results indicate that emotional blunting can be differentiated into two easily measured components which may have different clinical significance.

Affective Symptoms↗
PubMed1987

Cognitive dysfunction in melancholia.

Sixty-seven patients with melancholia and 42 normal controls were tested with a battery of neuropsychological tasks selected to assess regional cortical functioning in both hemispheres. Compared with controls, melancholics exhibited a pattern of bifrontal and right parietal impairment, which was independent of age, sex, handedness and drug administration. These findings confirm and extend prior studies and contrast with those we and others have reported in patients with schizophrenia.

Cognition Disorders↗
PubMed1987

Cognitive impairment patterns in schizophrenia and affective disorder.

A battery of neuropsychological tasks was used to study 62 schizophrenics, 67 melancholics, and 30 manics satisfying specific research diagnostic criteria, and 42 normal subjects. Two patterns of neuropsychological impairment among patients were identified by factor analysis. The first pattern of bifrontal, non-dominant hemisphere dysfunction was shared by schizophrenics and affectively ill patients, whereas the second pattern of dominant temporo-parietal-occipital impairment was most frequent in a subgroup of schizophrenics. These relationships remained after accounting for the effects of age, gender, handedness and drugs received at time of testing.

Adult↗
PubMed1987

ECT-induced EEG asymmetry and therapeutic response in melancholia: relation to treatment electrode placement.

Six right-unilateral and bilateral ECTs were equally effective in reducing Hamilton Rating Scale for Depression scores in 34 melancholic patients whose EEG symmetry did not change after ECT. However, a substantial therapeutic advantage was recorded for bilateral ECT in those patients whose EEG symmetry changed. Accentuation of ECT-induced EEG slowing over the right hemisphere was associated with right-unilateral ECT and a lesser treatment response, suggesting that the therapeutic advantage reported by some investigators for bilateral over right-unilateral ECT may be attributed to a poor outcome experienced by those unilateral ECT patients who developed right-sided EEG slowing.

Adult↗
PubMed1987

Identification of a repetitive genomic sequence that is distributed among a select group of mycoplasmas.

Homologous DNA sequences common to different Mycoplasma species were identified and isolated using interspecies DNA hybridization. Specific homologies were found in three species of porcine mycoplasmas that were not detected in species from other animal hosts. Restriction fragments bearing these common sequences were isolated from genomic libraries of M. hyorhinis and M. hyopneumoniae, and DNA sequence analysis confirmed the sequence conservation predicted from hybridization studies. Multiple homology signals were detected by probing M. hyorhinis genomic digests with the isolated restriction fragments, suggesting that these common sequences are present in many copies in that species. The repetition of this sequence is, however, more limited in the other porcine mycoplasma chromosomes.

Animals↗
PubMed1987

Maximum growth rate of Mycobacterium avium in continuous culture or chronically infected BALB/c mice.

Mycobacterium avium is a human pathogen which may cause either chronic or disseminated disease and the organism exhibits a slow rate of growth. This study provides information on the growth rate of the organism in chronically infected mice and its maximal growth rate in vitro. M. avium was grown in continuous culture, limited for nitrogen with 0.5 mM ammonium chloride and dilution rates that ranged from 0.054 to 0.153 h-1. The steady-state concentration of ammonia nitrogen and M. avium cells for each dilution rate were determined. The bacterial saturation constant for growth-limiting ammonia was 0.29 mM (4 micrograms nitrogen/ml) and, from this, the maximal growth rate for M. avium was estimated to be 0.206 h-1 or a doubling time of 3.4 h. BALB/c mice were infected intravenously with 3 x 10(6) colony-forming units and a chronic infection resulted, typical of virulent M. avium strains. During a period of 3 months, the number of mycobacteria remained constant in the lungs, but increased 30-fold and 8,900-fold, respectively, in the spleen and mesenteric lymph nodes. The latter increase appeared to be due to proliferation in situ. The generation time of M. avium in the mesenteric lymph nodes was estimated to be 7 days.

Ammonia↗
PubMed1986

Is homoeopathy a placebo response? Controlled trial of homoeopathic potency, with pollen in hayfever as model.

The hypothesis that homoeopathic potencies are placebos was tested in a randomised, double-blind, placebo-controlled trial. The study model chosen compared the effects of a homoeopathic preparation of mixed grass pollens with placebo in 144 patients with active hayfever. The homoeopathically treated patients showed a significant reduction in patient and doctor assessed symptom scores. The significance of this response was increased when results were corrected for pollen count and the response was associated with a halving of the need for antihistamines. An initial aggravation of symptoms was noted more often in patients receiving the potency and was followed by an improvement in that group. No evidence emerged to support the idea that placebo action fully explains the clinical responses to homoeopathic drugs.

Adolescent↗
PubMed1986

Quinazoline antifolates inhibiting thymidylate synthase: benzoyl ring modifications.

Four new analogues of the antifolate N10-propargyl-5,8-dideazafolic acid were prepared that were substituted in the benzoyl ring. The 2'-chloro and 2'-methyl analogues were prepared from the appropriately substituted p-nitrobenzoic acids. The route to the 3'-chloro and 3',5'-dichloro analogues was by chlorination of diethyl N10-propargyl-5,8-dideazafolate and diethyl N-[4-(prop-2-ynylamino)benzoyl]-L-glutamate, respectively, using sulfuryl chloride. The compounds were tested for their inhibition of purified L1210 thymidylate synthase (TS), for their inhibition of purified L1210 dihydrofolate reductase (DHFR), and for their inhibition of the growth of L1210 cells in culture. The 2'-chloro substituent reduced the TS inhibition by twofold and the 2'-methyl substituent reduced it by 20-fold; the 3'-chloro and 3',5'-dichloro derivatives were very poor inhibitors. The substituents only slightly affected the DHFR inhibition. None of the compounds improved upon N10-propargyl-5,8-dideazafolic acid in inhibiting the growth of L1210 cells in culture.

Folic Acid↗
PubMed1986

Quinazoline antifolates inhibiting thymidylate synthase: variation of the amino acid.

Five new analogues (1c-g) of the antifolate N10-propargyl-5,8-dideazafolic acid (1a) are described in which the benzoyl-L-glutamate moiety was replaced by benzoic acid (desglutamyl-N10-propargyl-5,8-dideazafolic acid), benzoyl-L-aspartate, 4-phenylbutyrate, benzoylglycine, and benzoyl-L-alanine. The esters of the appropriate 4-aminophenyl (benzoyl) starting materials were sequentially alkylated upon nitrogen, first with a propargyl halide and then with 2-amino-6-(bromomethyl)-4-hydroxyquinazoline hydrobromide. Saponification of the antifolate esters so produced gave the desired analogues. The new derivatives (1c-g) and also the known diethyl ester of 1a (1b) were tested for their inhibition of purified L1210 thymidylate synthase (TS) and for their inhibition of the growth of L1210 cells in culture. The TS inhibition of the analogues 1b-g was estimated by calculating the inverse relative potency, defined as the ratio IC50(compound)/IC50(1a). The results obtained were as follows: greater than 62, 84, 9, 333, 21, and 5, respectively. All were thus less inhibitory than 1a. None of the compounds improved upon 1a in inhibiting the growth of L1210 cells in culture.

Animals↗
PubMed1986

Concurrent psychiatric illness in non-Hispanic outpatients diagnosed as having posttraumatic stress disorder.

Twenty-five consecutive admissions to an outpatient group therapy program for combat veterans meeting DSM-III criteria for posttraumatic stress disorder were systematically screened using operational diagnostic criteria for other coexisting psychiatric conditions, past or present. Eighty-four percent had coexisting conditions which, with one exception, were not significantly different in prevalence from those of an inpatient sample of combat veterans previously reported by the authors. The exception was a lower frequency of drug dependence in the outpatients compared with the inpatients. The authors conclude that a high proportion of conditions and symptoms--particularly alcoholism, antisocial personality, drug abuse, depression, and anxiety--can be routinely expected to coexist with posttraumatic stress disorder when it is diagnosed in Vietnam combat veterans.

Adult↗