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Biomedical subjects

D Platt

Publications and source records attributed to D Platt.

At least 163 records · Page 9Linked to original sources
PubMed1982

Effect of linolenyl alcohol on the in-vitro growth of the oral bacterium Streptococcus mutans.

The effect of primary aliphatic alcohols of varying chain length and degree of unsaturation on bacterial growth was assessed, using Strep. mutans BHT as the main test organism. Unsaturated alcohols, linoleyl and linolenyl, effectively inhibited bacterial growth. Of the saturated alcohols, only lauryl and myristyl alcohols inhibited the growth of Strep. mutans BHT, but at concentrations much higher than those required for the unsaturated alcohols. All Gram-positive organisms tested were sensitive to linolenyl alcohol. Gram-negative bacteria did not exhibit the sensitivity. Linoleic and linolenic acid were inactive as antibacterial agents at the same concentration as the related alcohol. Repeated exposure of Strep. mutans BHT to linolenyl alcohol produced no change in the sensitivity of the organism to the alcohol. Significant amounts of linolenyl alcohol were found in bacteria grown in the presence of this lipid for 24 h but linolenic acid was not detected. Thus the primary polyunsaturated aliphatic alcohols, particularly linolenyl alcohol, could be effective antibacterial agents for the prevention of dental caries and periodontal disease.

Bacteroides fragilis↗
PubMed1982

Potentiation of MIF production by lymphocytes of Trichinella spiralis-infected mice.

In order to further investigate the mechanism involved in the immunopotentiation following Trichinella spiralis infection, mice were injected intraperitoneally with either heat-killed or viable bacillus Calmette-Guérin (BCG) 28 days after oral infection with 200 nematode larvae. Delayed-type hypersensitivity (DTH) was assessed 28 days later by measuring levels of migration inhibitor factor (MIF) elicited by Old Tuberculin challenge. Sensitization with killed BCG produced only negligible amounts of MIF; however, prior T. spiralis infection resulted in significantly increased titers of MIF, reaching levels induced by viable BCG. The data indicated that a lymphokine component may be involved in addition to non-specific mechanisms previously proposed.

Animals↗
PubMed1982

[Drug treatment in the elderly: special aspects of diuretics (author's transl)].

Age-dependent changes in the pharmacokinetics of two diuretics, spironolactone and triamterene, were investigated in 20 geriatric patients with multiple diseases. Average plasma concentrations of canrenone (both determined by High-Performance-Liquid-Chromatography (HPLC) and a fluorimetric method) were significantly higher in geriatric patients compared with a younger control group of healthy volunteers (p less than 0,002). There was also a significant positive correlation between age (of the geriatric patients) and the area under the plasma concentration curve of canrenone. Plasma concentrations of canrenone (measured by HPLC after 120 hours) were closely correlated with number of red cells in the geriatric patients (p less than 0,01). Maximum plasma concentrations of triamterene and its pharmacologically active phase-II-metabolite were clearly higher in the geriatric patients when compared with a younger control group of healthy volunteers. Maximum plasma concentrations of the phase-II-metabolite were inversely correlated with diastolic blood pressure (p less than 0,01). Plasma levels of triamterene and its phase-II-metabolite in the older patients seem to be influenced not only renal perfusion pressure but also by uric acid levels.

Age Factors↗
PubMed1982

[The significance of age dependent organ changes for therapy].

Age dependent physiological alterations of the organs are superposed by pathological changes. The increase of the number of diseases with higher age results in difficulties in drug therapy. As the elderly patients take more medications than younger patients there is an increased incidence of adverse drug reactions in the elderly. Drug elimination occurs principally by two ways: excretion of unchanged drugs by the kidney and of metabolised drugs by the liver and/or kidney. Age dependent changes of these both organs as well as of the stomach and intestine are discussed.

Aged↗
PubMed1981

[Phagocytosis activity of the isolated perfused liver in rats of different ages. Biochemical and ultrastructural examination after perfusion with colloidal ink].

Liver contains about 85% of reticulohistiocytic system. There are no problems to perfuse the isolated organ. The phagocytic activity was measured of young and old rat livers referred to phagocytosis of colloidal carbon. There is no difference between the phagocytic activity of young and old rat livers. The consumption of oxygen of rat livers increases with age.

Aging↗
PubMed1981

[On the pharmacokinetics of spironolactone in the elderly].

The pharmacokinetics of canrenone were compared in 10 elderly (77.2 years) patients and 10 young (20.1 years) female persons after multiple oral dosing of 100 mg Spironolactone during steady-state. The concentrations were determined using both a specific HPLC-assay and a nonspecific fluorometric assay. Maximum as well as mean concentrations of canrenone in serum of the elderly subjects were approximately twice as high as those in the young. This was the consequence of an impaired capacity for elimination of spironolactone in the elderly subject. In addition the ratio of the other fluorigenic metabolites and of canrenone were higher in the elderly. Thus also shifts in the metabolic pathways of spironolactone occur with progressing age.

Aged↗
PubMed1981

Lifespan of rabbit erythrocytes and activity of the reticulohistiocyte system.

The survival rate was measured of differently aged rabbit erythrocytes that had been taken from young and old animals, tagged with 51Cr and injected into young and old animals. The survival rate of the donor erythrocytes depends mostly on the age of the recipient animals. The life span of the injected cells found in old animals was much lower than that found in young animals. On the other hand, the age of the donor animal also has an influence, although only a small one, on the life span of the red blood cells. The cells from young animals live rather longer than those from old animals.

Aging↗
PubMed1981

Phagocytic activity of the reticulohistiocyte system in rabbits after splenectomy and activation with ink.

The survival rate was measured of differently aged rabbit erythrocytes that had been taken from young animals, tagged with 51Cr and injected into young and old animals. The recipient animals had either been splenectomized, or had an ink-activated reticulohistiocyte system, or both. In young as well as in old ink-treated animals the injected cells lived for a much shorter time than in the non-treated animals. In splenectomized animals the red blood cells lived a little longer than those in the control group. In animals which had been both splenectomized and ink-treated the 51Cr-tagged cells again lived for a shorter time than those in the control group, but longer than in the ink-treated animals.

Aging↗
PubMed1980

Diameters of erythrocytes of different ages measured by scanning electron-microscopy.

Contradictory reports exist about the age-dependent changes of erythrocyte diameters. All the investigations were carried out using Coulter Counter, by which the erythrocytes are sucked through a glass capillary. The contact with a glass surface causes the cell to deform instantly. This explains the lack of accuracy of the measurements subsequently taken. We measured the size of red cells of different ages by scanning electron-microscopy, thus avoiding deformations. We found that the average diameter decreases with the age of the red cell. The mean diameter was 7.77 microns in young cells, 7.34 microns in middle-aged and 7.00 microns in old cells.

Acanthocytes↗
PubMed1979

Multidisciplinary terms.

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Commitment of Persons with Psychiatric Disorders↗