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Biomedical subjects

J Mason

Publications and source records attributed to J Mason.

At least 271 records · Page 15Linked to original sources
PubMed1980

Electron microprobe analysis of intracellular elements in the rat kidney.

The concentrations of intracellular elements were determined by electron microprobe analysis in the nucleus and cytoplasm of freeze-dried cryosections of superficial proximal and distal tubules of the rat kidney. For the nucleus of the proximal tubular cell, the concentrations of sodium and chloride were 20 and 23 mmoles/kg of wet wt, and those of potassium and phosphorus were 144 and 150 mmoles/kg wet wt. For the nucleus of the distal tubular cell, the concentrations of sodium and chloride were significanlty lower (11 and 13 mmoles/kg wet wt), that of potassium was unchanged (143 mmoles), and that of phosphorus was significantly higher (175 mmoles). Towards the basolateral infoldings of the proximal and distal tubules and the brush border of the proximal tubules, the concentrations of sodium and chloride were higher and those of potassium and phosphorus were lower than those obtained in the nucleus, indicating the presence of extracellular compartments in these regions. Measurements performed in the centrally located cytoplasm of proximal and distal tubular cells, close to the nucleus, showed sodium and potassium concentrations to the indistinguishable from those in the nucleus, whereas chloride and phosphorus concentrations were considerably higher. These data demonstrate differences in the intracellular concentrations of phosphorus, sodium, and chloride between proximal and distal tubular cells. In neither the proximal nor the distal tubular cells, however, could a concentration difference for sodium and potassium between nucleus and cytoplasm be determined.

Animals↗
PubMed1980

The fate of 99Mo-labelled sodium tetrathiomolybdate after duodenal administration in sheep: the effect on caeruloplasmin (EC 1.16.3.1) diamine oxidase activity and plasma copper.

1. The effect of acute duodenal infusion of 99Mo-labelled sodium tetrathiomolybdate on caeruloplasmin (ferroxidase; EC 1.16.3.1) was examined in sheep. The diamine oxidase activity of this enzyme with respect to two substrates, p-phenylenediamine and o-dianisidine (both at their apparent Km concentrations) was inhibited. 2. The 99Mo appeared rapidly in plasma and was at first present predominantly in a trichloroacetic acid insoluble form; inhibition of oxidase activity was related to the levels of TCA-insoluble Mo. The behaviour of the copper prosthetic groups of caeruloplasmin was altered since some plasma Cu precipitated with the protein fraction after TCA treatment. The appearance of TCA insoluble Cu was related to the level of TCA-insoluble 99Mo and corresponded to the inhibition of diamine oxidase activity.

Amine Oxidase (Copper-Containing)↗
PubMed1980

Clotrimazole in rheumatoid arthritis.

Forty-seven patients with active rheumatoid arthritis took part in an 8-week controlled study in which clotrimazole was compared with a standard nonsteroidal anti-inflammatory agent, ketoprofen. Although clotrimazole was shown to be effective in the treatment of the disease and superior to ketoprofen in certain measurements, if was also responsible for a high incidence of adverse effects. Improvement with clotrimazole took place more slowly but was more sustained than with ketoprofen. A significant rise in plasma cortisol and a fall in white cell count was observed in the clotrimazole treated patients.

Arthritis, Rheumatoid↗
PubMed1980

The management of chronic schizophrenia.

With the movement of psychiatric patients from chronic mental hospitals to local communities over the past 20 years, family physicians have provided care for increasing numbers of chronic schizophrenia patients. The residual symptoms which these patients demonstrate require special communication skills on the part of the physician if a collaborative patient-physician relationship is to be established. The management of the disease should be founded on an understanding of its psychopathology. In this paper, the authors describe this psychopathology and suggest therapeutic interactions and interventions specific to the disease process.

Chronic Disease↗
PubMed1980

Biochemical parameters useful for the diagnosis of mild molybdenosis in sheep.

Three groups of ten young ewes (29 kg) received a basal diet or a diet enriched in sulphur (3 g/kg DM) or sulphur (3 g/kg DM) plus molybdenum (13 mg/kg DM). The total plasma copper increased in the S + Mo group. The trichloracetic acid (TCA) insoluble copper fraction of this group rose sharply from the second week of experiment. A decrease in ceruloplasmin oxidase activity could be detected in non-saturating or saturating substrate conditions in the enzyme assay, either with paraphenylenediamine or o-dianisidine as substrate. It was concluded that the decrease was due to failure of synthesis rather than inhibition. The plasma TCA insoluble copper fraction is thus the earliest and most reliable parameter for molybdenosis diagnosis in sheep.

Animals↗
PubMed1979

Intracellular elemental concentrations in renal tubular cells. An electron microprobe analysis.

In order to be able to examine the processes involved in transepithelial transport in tissues, which are not composed of a single cell type, methods are required, which permit analysis at a cellular level. The technique of electron microprobe analysis permits the intracellular concentrations of many elements to be determined simultaneously in various portions of the cell. The application of this method to renal cortical tissue has shown that the best estimates of the cytoplasmic concentrations are to be obtained in regions close to the nucleus, farthest from the basolateral infoldings and microvilli, which separate the intracellular environment from the extracellular space. The nuclear concentrations of Na and K do not differ from those in the surrounding cytoplasm, although those of P and Cl are somewhat higher in cytoplasm. The intracellular element concentrations in the different cell types vary somewhat, proximal tubular cells contain higher concentrations of Na and Cl and lower ones of P than distal tubular cells. Following ischaemia, a manoeuvre know to result in a disturbance of intracellular electrolytes, Na was observed to rise and K to fall only in the non-surface cells of kidneys exposed to the air, but in all cells, if the kidneys were kept air-free in an atmosphere of N2. The proximal and distal tubular cells showed a variable resistance to ischaemia, the distal tubular cells being much more resistant. Despite the severity of the electrolyte disturbance following ischaemia, the intracellular composition was completely restored one hour after re-introducing renal blood flow.

Animals↗
PubMed1979

The early phase of experimental acute renal failure. IV. The diluting ability of the short loops of Henle.

Experiments were conducted to establish whether diminished solute reabsorption in the loop of Henle during acute renal failure could explain the loss of urinary concentration and participate in generating a tubuloglomerular feedback-mediated reduction in filtration rate. The electrolyte content of the fluid in the ascending limb of the loop of Henle was determined in situ by monitoring its electrical conductivity after propulsion into the distal tubule with a sudden burst perfusion. The value of the minimum electrolyte concentration decreased exponentially with increasing equilibration time, reaching a steady-state value equivalent to 27 +/- 9 mM NaCl in normal kidneys, 34 +/- 15 mM in mercuric chloride kidneys and 53 +/- 22 mM following ischaemia. A mathematical model was derived to describe the process of sodium chloride dilution from which it was possible to calculate both the permeability and transport velocity of the cortical thick ascending limb. In the normal kidney, the transport velocity was calculated to be 4.65 +/- 0.92 . 10(-5) cm/s, a value not significantly different from that of the mercuric chloride of ischaemic kidneys, and the estimated permeability was 1.13 +/- 0.52 . 10(-5) cm/s, not different from that of the mercuric chloride kidneys but significantly lower than that calculated for the ischaemic kidneys. It is concluded that for the more severely damaged ischaemic model, the loss of urinary concentrating ability was accompanied by a reduction in diluting ability of the ascending limb of the short loop of Henle, which appears to be due, at least in part, to an elevation of the passive permeability to sodium chloride in this segment.

Acute Kidney Injury↗
PubMed1979

The early phase of experimental acute renal failure. V. The influence of suppressing the renin-angiotensin system.

Experiments were conducted to determine whether suppression of the renin-angiotensin-system and inhibition of the tubuloglomerular feedback response offer protection from acute renal failure, as found in chronically-salt loaded animals. The juxtaglomerular renin activity and tubuloglomerular feedback response were inhibited acutely, by saline expansion, or chronically, by DOCA-treatment with saline drinking fluid or salt diet, by high salt diet alone, or by inducing two-kidney Goldblatt hypertension. The chronic pretreatment procedures depressed juxtaglomerular renin to 16, 7, 13 and 4% of control, respectively, inhibited the feedback response to 53, 37, 56, and 38% of control, respectively, but conferred no benefit in the first hours following a nephrotoxin or ischaemia. In contrast, the acute treatment procedure reduced juxtaglomerular renin activity to only 56% and lowered the feedback response to only 71%, but improved renal function after the nephrotoxin, although not after ischaemia. It is concluded that since severe restrictions of renin activity and tubuloglomerular feedback are not protective, neither is primarily involved in generating the functional restrictions early in acute renal failure. The restoration of renal function by saline expansion accompanied only a modest depression of these two systems and suggests that the beneficial effect may result more from volume expansion or diuresis than from suppression of renal renin or inhibition of tubuloglomerular feedback.

Acute Kidney Injury↗
PubMed1979

Cardiac abnormalities in myotonic dystrophy. Electrophysiologic and histopathologic studies.

Eight young adult male patients with myotonic dystrophy, mean age 26 years, underwent 24-hour Holter electrocardiographic monitoring and intracardiac electrophysiologic study. Right ventricular endomyocardial biopsies were performed at the end of the electrophysiologic study in five of them. The atrial to His[A-H] interval was 155 msec in one case and less than or equal to 55 msec in all patients. Twenty-four hour Holter electrocardiographic monitoring demonstrated more than 4 premature ventricular contractions per minute in two patients and marked cyclical sinus arrhythmia during sleep in two others. Electron microscopic analysis of the endomyocardial biopsy specimens disclosed no prominent sarcoplasmic reticulum abnormalities but prominent I bands compared to previously obtained controls. Myofibrillar degeneration was seen in all cases and was associated with abnormal mitochondria in two. Cardiac abnormalities can be detected very early in the evolution of myotonic dystrophy, even prior to the onset of cardiac symptoms. The reported abnormalities appear closely related to the pathologic process affecting other skeletal muscles.

Adolescent↗
PubMed1979

Multiple sclerosis-associated agent. Failure of MS brain and serum to depress the polymorph count in normal mice and mice inoculated with cells containing C/type particles.

The groups that originally reported and confirmed the demonstration of a multiple sclerosis associated agent (MSAA) are now, along with others, unable to reproduce this effect. In view of this confusion and the potential importance of this work for multiple sclerosis (MS) we have done a strict double-blind trial using larger groups of mice (10) and counting more cells (900) than in previous reports to offset the high variability of mouse polymorphonuclear neutrophil (PMN) counts. Sera from 5 active MS patients and 4 normal subjects were tested in mice, half of which had previously been injected with PAM line cells (containing C-type particles and subject to reduced cell yield when cultured with MS brain extract). No significant PMN depression was found in either MS or normals on any basis of comparison. However, a significant depression was seen following PAM cell injection irrespective of serum origin. Higher counting accuracy did not reduce PMN variability. A single MS brain specimen was also without effect. consequently we have been unable to confirm the existence of an MSAA as defined by PMN depression in mice.

Animals↗
PubMed1979

The effect of tetrathiomolybdate upon sheep caeruloplasmin amine oxidase activity in vitro: the influence of substrate on apparent sensitivity to inhibition.

The effect of molybdate, dithiomolybdate, tetrathiomolybdate and diethyldithiocarbamate on caeruloplasmin amine oxidase activity was examined using o-dianisidine as a substrate. Enzyme activity was strongly inhibited by tetrathiomolybdate (1.5 X 10(6)M), oxidation of another substrate, p-phenylenediamine, was inhibited only slightly.

Animals↗
PubMed1979

A study of occupational status, responsibility and authority in patients with duodenal ulcers, other gastrointestinal diseases and controls.

Five hundred and twenty-two African and Indian patients were studied, including 206 with duodenal ulcers, 25 with irritable colon, 51 with oesophagitis, 31 with pancreatitis, 14 with ulcerative colitis or Crohn's disease, 71 miscellaneous gastrointestinal diagnoses and 124 controls. The mean ages were similar in each group. Every patient underwent endoscopy and a detailed psychosocial questionnaire was applied. Comparison of occupations of patients and their patients was investigated on 3 scales, for Status/Prestige (9 levels), Responsibility (5 levels) and Control over Others (10 levels). Significantly more patients with duodenal ulcers were in the lowest group in terms of occupational authority compared to other diagnoses and controls. Similar number of all groups had been urban for their entire life. Stress was present in the 10 days preceding an attack in significantly more Indian males with duodenal ulcers compared to controls. Upward shifts in prestige had not occurred in African male patients with duodenal ulcers when compared to their parents but had occurred among Indian men. More duodenal ulcer patients were in the very lowest occupational authority category compared to other groups. It may thus not be occupational prestige as such that is important, but factors associated with it, such as lack of control over others and, among Indian men, stresses associated with social disruption following upon occupation mobility.

Africa↗
PubMed1979

Intracellular electrolyte concentrations in epithelial tissue during various functional states.

The scanning electron microscope together with an energy dispersive system was used to quantify intracellular elemental concentrations of transporting epithelial cells under a variety of experimental conditions. In the frog skin, the Na transport pool is comprised of the intracellular compartments of all vital cells in the different cell layers, except the mitochondria rich cells. The Na content of this transport pool exchanges easily with the epithelial (outer) bathing solution. Vasopressin increases the Na permeability of the corial cell barrier. Proximal and distal tubular cells of the rat kidney show differences in the pattern of intracellular element concentrations. The distal tubular cell is more resistant to 20 min of ischemia than the proximal cell. The changes in intracellular electrolyte concentrations following 60 min of ischemia are reversible after reperfusing the kidney with blood for 60 min. In the cells of the frog skin and rat kidney, Na and K were equally distributed between the cytoplasm and the nucleus. Differences exist for P, Cl and dry weight.

Amiloride↗