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B Stanley

Publications and source records attributed to B Stanley.

At least 55 records · Page 3Linked to original sources
PubMed1988

Structure and regulation of mammalian S-adenosylmethionine decarboxylase.

In order to understand the structure and regulation of S-adenosylmethionine decarboxylase, cDNA clones encoding this enzyme have been isolated from rat prostate and human fibroblast cDNA libraries. The authenticity of the cDNAs was verified by: (a) transfecting the Chinese hamster ovary cells with the human cDNA in the pcD vector which resulted in a transient 10-20-fold increase in S-adenosylmethionine decarboxylase activity in recipient cells; and (b) translating the mRNA formed by transcription of the cDNA insert in a reticulocyte lysate and recording an increase in S-adenosylmethionine decarboxylase activity. The amino acid sequences deduced from the cDNAs indicate that the human proenzyme for this protein contains 334 amino acids and has a molecular weight of 38,331 whereas the rat proenzyme contains 333 amino acid residues. The human and rat enzymes are very similar having only 11 amino acid differences and the cDNAs are also closely related showing over 90% homology in the 1617-nucleotide overlap which was sequenced. A further indication of the highly conserved nature of mammalian S-adenosylmethionine decarboxylases is that the amino acid sequences deduced from the human and the rat cDNAs contained peptide sequences identical to those previously reported for the purified bovine enzyme. In vitro transcription/translation experiments showed that the proenzyme is converted to two polypeptides of molecular weights about 32,000 and 6,000 in a processing reaction which generates the prosthetic pyruvate group and that the final enzyme contains both polypeptides. Two forms of S-adenosylmethionine decarboxylase mRNA (2.1 and about 3.4-3.6 kilobases) are present in human and rodent tissues and may originate from the utilization of two different polyadenylation signals. Southern blots of rat genomic DNA indicated that the S-adenosylmethionine decarboxylase gene belongs to a multigene family. Depletion of cellular polyamines by inhibitors or ornithine decarboxylase or the aminopropyltransferases led to an increase in the content of S-adenosylmethionine decarboxylase protein and mRNA, but the elevation in the mRNA was not sufficient to account for all of the change in the enzyme level, particularly in cells in which spermine was depleted.

Adenosylmethionine Decarboxylase↗
PubMed1988

Regulation of mammalian S-adenosylmethionine decarboxylase.

S-Adenosylmethionine decarboxylase is a key enzyme in the biosynthesis of polyamines that is the rate limiting step in the formation of spermidine and spermine. The activity of S-adenosylmethionine decarboxylase is known to be regulated negatively by these polyamines and positively by their precursor, putrescine. A specific antiserum to S-adenosylmethionine decarboxylase was raised by immunizing rabbits with the homogeneous enzyme purified from rat prostate and a specific radioimmunoassay for the protein was set up. Using this radioimmunoassay it was found that a number of inhibitors of other steps in the polyamine biosynthetic pathway lead to increases in the amount of S-adenosylmethionine decarboxylase protein. These changes were caused by both a decreased rate of degradation and an increased rate of synthesis of the protein. The increased synthesis was due to two factors; a rise in the amount of translatable mRNA and an enhanced translation efficiency. The mRNA content of the prostate was substantially increased by treatment for 3 days with alpha-difluoromethylornithine (2% in drinking water). The translation of mRNA for S-adenosylmethionine decarboxylase was studied using a polyamine-depleted reticulocyte lysate supplemented with mRNA from rat prostate and the antiserum to precipitate the proteins corresponding to S-adenosylmethionine decarboxylase. These studies indicated that the enzyme was synthesized as an inactive precursor of Mr 37,000 which was converted to the enzyme sub-unit of Mr 32,000. The conversion of the precursor to the active sub-unit in vitro was increased by putrescine. The precursor could also be detected by immunoblotting of extracts from prostates of rats depleted of putrescine by treatment with the ornithine decarboxylase inhibitor, alpha-difluoromethylornithine. The translation of the S-adenosylmethionine decarboxylase mRNA in the reticulocyte lysates was strongly inhibited by the addition of spermidine or spermine demonstrating that polyamines directly inhibit the synthesis of S-adenosylmethionine decarboxylase. cDNA clones corresponding to S-adenosylmethionine decarboxylase were isolated using prostatic mRNA from polysomes enriched in S-adenosylmethionine decarboxylase by immunopurification. The use of these probes showed that rat ventral prostate contains two S-adenosylmethionine decarboxylase mRNA species of approximately 3.4 and 2.1 kb which differ in the 3' non-translated sequence. The sequence of these cDNAs will enable the amino acid sequence of the precursor to be obtained. This will provide evidence on the origin of the pyruvate prosthetic group of S-adenosylmethionine decarboxylase.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosylmethionine Decarboxylase↗
PubMed1988

N-acetylation and serotonergic measures in a group of psychiatric patients.

Serotonin is N-acetylated to melatonin. The purpose of this study was to explore the possibility of N-acetylation of dapsone reflecting serotonergic activity. The ratio of monoacetyldapsone/dapsone (MAD/DDS) in plasma, 5-HIAA in CSF, and imipramine-binding to platelets were investigated in a group of psychiatric patients, diagnosed according to the DSM-III as affective disorders, schizophrenia, and personality disorders. There was no significant correlation between either of the serotonergic estimates and N-acetylation in the whole patient group or in diagnostic subgroups of patients. Sixty-four percent of the patients were slow N-acetylators (MAD/DDS less than 0.4), which is a ratio in line with several other studies of psychiatric patients. Among patients with affective disorders, all unipolar patients were slow N-acetylators, while five out of six bipolar patients were fast N-acetylators. The N-acetylation of patients with a history of suicide attempt did not differ from those without. The discrepancy in N-acetylation between uni- and bipolar patients might again address the issue of them representing two different biochemical and genetic disorders.

Acetylation↗
PubMed1988

Congenital hypothyroidism in Scottish Deerhound puppies.

Two Scottish Deerhound puppies had clinical and pathological features consistent with the diagnosis of congenital non-goitrous hypothyroidism. They were from separate litters, but were the progeny of the same sire and dam. The puppies were smaller, had shorter limbs and shorter, broader heads than their littermates. They also had histories of weakness, difficulty in walking and somnolence. A characteristic radiographic feature was the absence of epiphyseal growth centres. Both had depressed serum thyroxine (T4) levels and one did not respond to exogenous thyroid stimulating hormone. On necropsy, the thyroid glands were small, the follicles varied in size and contained little or no colloid. The adenohypophysis contained many cells with markedly vacuolated cytoplasm. It is suggested that the clinicopathological pattern is the result of a primary thyroid abnormality. Possible mechanisms include either primary thyroid hypoplasia or an unresponsiveness to thyroid stimulating hormone.

Animals↗
PubMed1988

Psychological problems in general practice patients: two assumptions explored.

Research is needed into the scientific basis for psychologists' 'specialist' model of service to general practitioners. This study evaluated two predictions of this service to general practitioners. This study evaluated two predictions of this model: firstly, that patients with psychological problems can be identified reliably; secondly, that they tax GPs' resources and ability disproportionately. To test these, psychologists observed 448 GP consultations. The GP and psychologist independently rated the involvement of psychological factors; the GP recorded his satisfaction with, and the psychologist the duration of, the consultation. Patients completed scales of psychiatric and social dysfunction. Both predictions were confirmed. Agreement between GPs' and psychologists' ratings of the presence of psychological factors was higher than reported previously, and not explained by the small correlation of psychiatric morbidity with each. Problems identified by GPs as psychological were associated with longer, repeated and less satisfying consultations.

Adult↗
PubMed1985

The prevalence of chronic psychiatric morbidity: a community sample.

Several studies have commented upon the false negatives which can result when the General Health Questionnaire (GHQ) is employed as a community screening device for psychological distress. It would appear that some false negatives are the result of individual or cultural factors, whilst others result from the phrasing of the GHQ questions, which may mislead patients suffering from chronic disorders. This paper reports the use of additional questions, designed to detect such chronicity.

Adolescent↗