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Biomedical subjects

M Davies

Publications and source records attributed to M Davies.

At least 523 records · Page 29Linked to original sources
PubMed1978

Effect of BCG on alloimmune cell-mediated cytotoxicity in (C57BL/6Jfemale x A/Jmale)F1 mice. I. Effect of different BCG treatments on cytotoxicity mediated by T-cells and macrophages.

The effect of BCG on the development of cell-mediated cytotoxicity (CMC) in the spleens of allogeneic tumor-bearing female (C57BL/6Jfemale x A/Jmale)F1 mice was studied. BCG-treated tumor-bearing animals elicited a stronger CMC response than did the untreated tumor-bearing animals. Furthermore, the degree of activation was dependent on the time, route of injection, and dose of BCG. Therefore, if the BCG was administered at suboptimal conditions, a less marked stimulation of the CMC resulted. A combination of a high BCG dose given iv 12 days before implant of P815 tumor cells and a low, second dose given at the time of implant produced the most marked activation of the CMC response. By the use of in vitro technique, the specific CMC was mediated mostly by T-cells, with macrophages making a less significant contribution.

Animals↗
PubMed1978

Effect of BCG on alloimmune cell-mediated cytotoxicity in (C57BL/6Jfemale x A/Jmale)F1 mice. II. Correlation with BCG activity in syngeneic tumor systems.

The effectiveness of selected BCG regimens to produce an activation of cell-mediated cytotoxicity (CMC) in an allogeneic tumor system was compared with its ability to cause tumor regression in syngeneic tumor systems. In the tumor system selected in both inbred LEW rats and inbred C57BL/6J and (C57BL/6Jfemale x A/Jmale)F1 mice, a correlation was observed in that BCG treatments that caused marked CMC activation in the allogeneic tumor systems also effectively caused tumor regression and increased animal survival in syngeneic systems. It was concluded that the allogeneic CMC reaction can be used to predict the capacity of BCG to cause tumor rejection.

Animals↗
PubMed1978

The natural history of a non-stenotic bicuspid aortic valve.

Forty-one patients in whom the diagnosis of a non-stenotic bicuspid aortic valve had been established by noninvasive techniques were followed up for a mean of 10.9 years. During this period, 2 patients required aortic valve replacement because of the development of calcific aortic valve stenosis at the ages of 52 and 64 and 5 others developed evidence of mild aortic valve stenosis. The appearance of calcium in a bicuspid aortic valve suggests the possibility of subsequent calcific aortic stenosis, and patients with this feature should be carefully followed up. Bacterial endocarditis on the aortic valve occurred in 3 patients, one of whom developed severe aortic regurgitation and subsequently died. Patients with a bicuspid aortic valve are at definite risk from bacterial endocarditis and should receive appropriate antibiotic prophylaxis. In 26/41 (63%) patients there was no clinical change during the follow-up period, including 7 of the patients over the age of 50.

Adolescent↗
PubMed1978

Age-related changes in Purkinje fiber action potentials of adult dogs.

To determine the effects of age on electrophysiological properties of Purkinje fibers (PF), we used standard microelectrode techniques to study PF from normal beagles of five age groups: 19.1 +/- 0.8, 63.7 +/- 2.6, 88.3 +/- 1.9, 107.2 +/- 1.6, and 132.3 +/- 4.3 months (mean +/- SE). Maximum diastolic potential (MDP) did not change over this age range. Action potential (AP) amplitude and maximum upstroke velocity of phase 0 (Vmax) attained peak values at 63.7 months and then declined. As age increased there was an increase in phase 1 repolarization, a prolongation in the time to the peak of the plateau, and a decrease in plateau height. AP duration reached a maximum at 63.7 months and thereafter remained unchanged. Fibers were superfused with the slow channel blocker, AHR-2666, and the fast channel blocker, tetrodotoxin (TTX). AHR-2666 had age-related effects on AP duration, phase 1 repolarization, plateau height, and time to the peak of the plateau. There were no age-related changes in TTX effects on phases 0--2. In another series of experiments, Purkinje fibers from dogs 23 +/- 1.2 to 106 +/- 1.4 months old were superfused with a calcium-rich solution in which Na+ was replaced by tetraethylammonium (TEA+). The resultant slow response action potentials, which are calcium dependent, showed an age-related decrease in AP amplitude, Vmax, and time to peak amplitude. When these fibers were superfused with the slow channel blocker, verapamil, there was an age-related effect on AP amplitude. Our studies indicate that in the normal aging heart, major changes occur in repolarization that appear, in the main, to result from change in the slow inward current carried by Ca2+.

Action Potentials↗
PubMed1978

The binding of adjuvant-active mycobacterial peptidoglycolipids and glycopeptides to mammalian membranes and their effect on artificial lipid bilayers.

The nature of the binding of adjuvant-active amphiphilic mycobacterial peptidoglycolipids and glycopeptides to mammalian plasma membranes was investigated together with their effect on the stability of artificial lipid bilayers. The importance of these interactions between mycobacterial components and membranes is discussed in relation to immunopotentiation, mitogenicity and tuberculous infection.

Adjuvants, Immunologic↗
PubMed1977

Treatment of fulminant hepatic failure by polyacrylonitrile-membrane haemodialysis.

24 patients with fulminant hepatic failure who had deteriorated to grade-IV coma were treated by repeated periods of haemodialysis with a polyacrylonitrile membrane. 9 patients fully recovered consciousness, and 8 (33%) survived to leave hospitals. These results are to be compared with those of conservative management alone (15% survival in 53 cases) and those obtained initially with charcoal haemo-perfusion (38%). Of the 16 treatment failures, cerebral oedema was found at necropsy in 13 (18%). Whether this would have been less of problem if treatment had been started earlier in the course of the illness remains to be determined.

Acrylonitrile↗
PubMed1977

1,25-dihydroxycholecalciferol in hypoparathyroidism.

8 patients with hypoparathyroidism have been treated successfully with 1,25-dihydroxycholecalciferol (0-25-1-0 mug/day) for 4-24 mo. Normal serum-calcium levels were restored in all patients, but half the patients required supplementary oral calcium. Treatment reduced serum-phosphorus in all patients, but values remained high in 3, and the renal-tubular reabsorption of phosphate returned to normal in only 2 of the 8 patients. A comparison is made with the effects of oral therapy with massive amounts of calcium salts. The data obtained are discussed in relation to the probable mode of therapeutic action of 1,25-dihydroxycholecalciferol.

Administration, Oral↗
PubMed1977

Effect of different doses of BCG on an allogeneic cell-mediated antitumor response in mice.

The effect of BCG on the development of cell-mediated cytotoxicity (CMC) in the spleens of allogeneic tumor-bearing (C57BL/6 X A)F1 mice was studied. BCG-treated tumor-bearing animals elicited a stronger CMC response than did the untreated tumor-bearing animals. Furthermore, the degree of activation was dependent on different doses of BCG, so that if the BCG was administered at doses above or below the optimum dose, a less marked stimulation of the CMC resulted. The combination of BCG given before the tumor implant plus an intratumor inoculation resulted in a significantly higher CMC than did either treatment alone.

Animals↗
PubMed1977

An outbreak of infection caused by a gentamicin-resistant Staphylococcus aureus.

An outbreak of infection caused by a strain of Staphylococcus aureus resistant to gentamicin and tobramycin and other antibiotics occurred in two wards in a hospital. Eight patients were colonized, of whom six had clinical infections. Previous administration of gentamicin appeared to predispose the patients to infection with the strain. Restriction of the use of gentamicin and tobramycin is essential to preserve their value in serious infections.

Anti-Bacterial Agents↗
PubMed1977

Vitamin D metabolism and the response to 1,25-dihydroxycholecalciferol in Osteoporosis.

The metabolism of isotopically-labelled cholecalciferol and the response to small doses of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was studied in a group of women with osteoporosis presenting with crush vertebral fracture. No abnormality of vitamin D metabolism was detected. The administration of 1 microgram 1,25-(OH)2D3 for between 8 and 20 days was associated with an increased intestinal absorption and urinary excretion of calcium but caused no improvement in calcium balance. There was a small but significant rise in serum calcium and phosphorus and significant reduction in immunoassayable parathyroid hormone levels during treatment. It is concluded that 1,25-(OH)2D3 is unlikely to be of value in the management of osteoporosis.

Aged↗