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Biomedical subjects

A Morrison

Publications and source records attributed to A Morrison.

At least 145 records · Page 8Linked to original sources
PubMed1980

Effects of urinary tract obstruction on renal function.

This paper reviews the effects of urinary tract obstruction of renal function. The mechanisms by which obstruction decreases glomerular filtration rate and renal plasma flow are considered. The effects of obstructive uropathy on renal concentrating ability, renal acid excretion, and renal metabolism are also discussed.

Animals↗
PubMed1979

Poly(adenosine diphosphate ribose) synthetase activity in nuclei of dividing and of non-dividing but differentiating intestinal epithelial cells.

Poly(ADP-ribose) synthetase activity is found in nuclei of regenerating epithelial cells in the lower half of the crypts of guinea-pig small intestine. Nuclei from non-dividing but differentiating and maturing cells in the upper crypts and on the villi contain no more than about 10% of the synthetase activity of lower-crypt cell nuclei. The product in the active nuclei is shown to be 80% poly(ADP-ribosylated) protein and 20% mono(ADP-ribosylated) protein; 60% of thetotal labelled product was attached to acid-soluble proteins (including histones), and 40% to acid-insoluble (non-histone) proteins. The average number of ADP-ribosyl units in the oligomeric chains of the poly(ADP-ribosylated) proteins was 15 but the range of sizes of (ADP-ribose) oligomers attached to nuclear proteins was smaller in villus than in crypt cell nuclei.

ADP Ribose Transferases↗
PubMed1979

Site-specific cleavage of DNA by E. coli DNA gyrase.

E. coli DNA gyrase, which catalyzes the supercoiling of DNA, cleaves DNA site-specifically when oxolinic acid and sodium dodecylsulfate are added to the reaction. We studied the structure of the gyrasecleaved DNA because of its implications for the reaction mechanism and biological role of gyrase. Gyrase made a staggered cut, creating DNA termini with a free 3' hydroxyl and a 5' extension that provided a template primer for DNA polymerase. The cleaved DNA was resistant to labeling with T4 polynucleotide kinase even after treatment with proteinase K. Thus the denatured enzyme that remains attached to cleaved DNA is covalently bonded to both 5' terminal extensions. The 5' extensions of many gyrase cleavage fragments from phi X174, SV40 and Col E1 DNA were partially sequenced using repair with E. coli DNA polymerase I. No unique sequence existed within the cohesive ends, but G was the predominant first base incorporated by DNA polymerase I. The cohesive and sequences of four gyrase sites were determined, and they demonstrated a four base 5' extension. The dinucleotide TG, straddling the gyrase cut on one DNA strand, provided the only common bases within a 100 bp region surrounding the cleavage sites. Analysis of other cleavage fragments showed that cutting between a TG doublet is common to most, or all, gyrase cleavages. Other bases common to some of the sequenced sites were clustered nonrandomly around the TG doublet, and may be variable components of the cleavage sequence. This diverse recognition sequence with common elements is a pattern shared with several other specific nucleic acid-protein interactions.

Base Sequence↗
PubMed1979

The "Newsletter": a catalyst for learning in group psychotherapy.

This article reports on an experiment in which members of a therapy group were invited to take turns doing process recordings of meetings, which were then circulated weekly to all members. The history of this "Newsletter," its benefits, the therapeutic goals, and the resistance it encountered are described. The method is seen as a potentially enriching tool for group psychotherapy.

Adult↗
PubMed1978

Adenylate cyclase of human parathyroid gland.

Experiments were performed on a particulate fraction from human parathyroid glands. A high activity of adenylate cyclase was detected which was linear with time and protein concentration. The enzyme had an optimum pH in the range of 7-8 and a Km for ATP of 0.44 X 10(-3) M. Ca++ had a profound inhibitory effect; a concentration of 0.5 mM Ca++ reduced enzyme activity by 60%. Maximal enzyme activity was obtained with 5 mM Mg++; higher concentrations of this cation also inhibited enzyme activity. The effect of Mn++ was similar to that of Mg++. Enzyme activity was stimulated by NaF, catecholamines, glucagon, and calcitonin. The effect of catecholamines seems to be mediated through beta-adrenergic receptors.

Adenoma↗
PubMed1977

ECT and the media.

Explore the source record for details and available documents.

Communication↗
PubMed1977

Exaggerated prostaglandin biosynthesis and its influence on renal resistance in the isolated hydronephrotic rabbit kidney.

Basal and hormone-stimulated prostaglandin biosynthesis was compared in isolated perfused rabbit kidneys with and without ureteral obstruction. At 72 h there was enhanced responsiveness to bradykinin in the ureter-obstructed hydronephrotic kidney. The amount of prostaglandin-like substance released from the perfused kidneys by 25 ng of bradykinin was 533+/-163 ng from the ureter-obstructed, 28+/-4 ng from the contralateral, and 26+/-3 ng from the normal kidney. The enhanced response was also noted with angiotensin II and with norepinephrine. This exaggerated responsiveness by the ureter-obstructed kidney could not be explained by decreased prostaglandin (PG) destruction or by decreased renal peptide inactivation (bradykinin or angiotensin). There was no enhanced PG biosynthesis with exogenous arachidonate, suggesting there was no increase in cyclo-oxygenase activity in the ureter-obstructed kidney. Renal tubular transport of PG from medulla to cortex was apparently not essential for the enhanced PG biosynthesis to hormone stimulation since the same exaggerated responses were noted during perfusion with the ureter ligated. The cyclo-oxygenase inhibitor, indomethacin, increased basal perfusion pressure in the obstructed kidney and enhanced the magnitude and duration of the renal vasoconstriction produced by angiotensin II in the hydronephrotic kidney. These results suggest that the local exaggerated biosynthesis of PG may be occurring in the cortical resistance vessels and may be important to the alteration in blood flow and excretory function that occur in ureteral obstruction.

Adenosine Triphosphate↗
PubMed1976

Inhibitory effects of hypermagnesemia on the renal action of parathyroid hormone.

Available evidence indicates that serum magnesium (Mg++) levels influence the secretion rate of parathyroid hormone (PTH). Whether serum Mg++ concentrations also modify the action of PTH on its target organs has not been definitively established. The present experiments were designed to study this possibility. The effect of infusing PTH on the urinary excretion of cyclic AMP (cAMP) and PO4= was examined in five normal dogs at two different levels of serum Mg++. At normal serum Mg++ concentrations (1.89 +/- 0.14 mg/100 ml), PTH infusion increased cAMP excretion from 1.76 +/- 0.27 to 4.87 +/- 1.00 nmol/min and fractional PO4= excretion (FEPO4) from 1.58 +/- 0.36% to 23.1 +/- 2.17%. When an identical amount of PTH was given to the same dogs at a serum Mg++ of 4.36 +/- 0.20 mg/100 ml, FEPO4 increased to only 6.02+/-1.89% and cAMP from 1.31 +/- 0.23 to 1.89 +/- 0.39 nmol/min. Identical results were obtained in thyroparathyroidectomized hypermagnesemic dogs. Increased serum Mg++ levels had no effect on the phosphaturia produced by the infusion of dibutyryl cAMP to thyroparathyroidectomized dogs. In vitro studies using rat renal cortical slices revealed a progressive decrease in cAMP production in response to PTH as the Mg++ concentrations were increased in the incubation medium. The overall results indicate that hypermagnesemia inhibits the phosphaturic response to PTH by decreasing the renal production of cAMP. Plasma magnesium, therefore, may participate in a double feedback mechanism, not only controlling the release of PTH, but also altering the biological activity of the hormone at the level of the target organ.

Adenylyl Cyclases↗
PubMed1974

The behaviour of oligodeoxynucleotides on thin-layer chromatography on polyethyleneimine-cellulose and ion-exchange paper electrophoresis. Applications in fractionating and sequencing terminally labelled oligodeoxynucleotides.

The electrophoretic behaviour of oligodeoxynucleotides on ion-exchange papers was studied systematically with particular attention to applications in sequence analysis. Complex mixtures of larger oligonucleotides were fractionated by electrophoresis on cellulose acetate followed by t.l.c. on polyethyleneimine-cellulose. The behaviour of the oligonucleotides on polyethyleneimine-cellulose and on the two-dimensional system can provide a useful guide to their sequence. Detailed results from some of these experiments have been deposited as Supplementary Publication SUP 50031 (13 pages) at the British Library (Lending Division) (formerly the National Lending Library for Science and Technology), Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1973), 131, 5.

Adenosine Triphosphate↗