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Biomedical subjects

T R Williams

Publications and source records attributed to T R Williams.

At least 55 records · Page 3Linked to original sources
PubMed1985

Iron accumulation during development and ageing of Drosophila.

We examined Drosophila melanogaster fruit flies to determine whether iron accumulates with ageing as it does in mice. Iron concentrations were measured by atomic absorption for flies maintained at 11, 20, 25 and 30 degrees C where the average lifespans were 152, 81, 62 and 25 days, respectively. Iron was found to accumulate with ageing during both the adult and developmental stages with an overall increase of 186% at 25 degrees C. A similar increase was found at 20 degrees C and 30 degrees C. At 11 degrees C the increase was less than half that at 25 degrees C. The rate of iron accumulation also varied with environmental temperature with the logarithm of the rate proportional to temperature (log R = 0.0509T-0.384). The rate of iron accumulation with ageing was, thus, found to be proportional to the rate of ageing, suggesting that excess dietary iron may be an initiator of senescence.

Aging↗
PubMed1985

Influence of anti-inflammatory agents on the survival of Drosophila.

Various anti-inflammatory compounds were tested for their influence on the life span of the fruit fly (Drosophila melanogaster). 2,3-dihydroxybenzoic acid increased the median life span by 10.9% when fed to adults at a concentration of 1 X 10(-5)M for the entire adult life span. All other anti-inflammatory compounds including acetylsalicylic acid, acetylsalicylic acid plus cupric chloride, Bufferin, chlorpromazine HC1, dimethylsulfoxide, indomethacin, phenol, salicylic acid, and sodium salicylate either decreased or did not change the life span. Rearing flies on 0.5% (0.060M) dimethylsulfoxide caused a 33.3% reduction in life span compared with an 11.8% reduction when fed during adulthood only. At low doses all of the anti-inflammatory compounds including dimethylsulfoxide proved to be nontoxic as measured by changes in life span.

Aging↗
PubMed1985

Excess dietary aluminum increases Drosophila's rate of aging.

Aluminum concentrations in the whole organism increased during development and aging of Drosophila melanogaster. The amount of aluminum in the flies was also reflected by the dietary content of aluminum. Additional dietary aluminum, in the form of aluminum salts, decreased the life span by as much as 20%. A significant reduction in life span was found for 1 X 10(-4) M aluminum chloride and for 1 X 10(-3) M aluminum nitrate and aluminum sulfate. Dietary sodium fluoride failed to increase life span.

Aging↗
PubMed1984

Influence of dietary copper on the survival of Drosophila.

The life span of Drosophila melanogaster was reduced when copper compounds were fed at concentrations of 1 X 10(-3) M or greater. Feeding lower concentrations of copper compounds failed to significantly change life span. A combination of copper gluconate and gluconic acid increased the adult life span by 21.6%. We conclude that only an extraordinarily high dietary intake of copper would accelerate senescence. Dietary gluconic acid retarded the normal age-related accumulation of copper in adult flies.

Animals↗
PubMed1983

Influence of dietary cadmium and chelators on the survival of Drosophila.

Dietary cadmium chloride at concentrations of 1 X 10(-4) M or greater shorten the life span of Drosophila melanogaster by as much as 74%. The chelator, CDTA, inhibits the normal age-related cadmium accumulation in whole flies and also improves the median life span by 20%. These data are interpreted to indicate that dietary cadmium may be a determining factor for the onset of senescence.

Aging↗
PubMed1983

[Low back pain].

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Back Pain↗
PubMed1982

Propranolol uptake by dog lung: effect of pulmonary artery occlusion and shock lung.

First-pass lung uptake of propranolol in catheterized ambulant dogs was measured by comparison the difference between the ratios of [14C]propranolol to indocyanine green (ICG) before and after a single passage through the pulmonary circulation. Uptake was 56 +/- 5, 53 +/- 8, and 61 +/- 10% (mean +/- SD) when 0.02, 0.2, and 2.0 mg of propranolol were injected, respectively. There was a negative though unimportant correlation between percent uptake and cardiac output. Analysis of paired propranolol and ICG outflow curves confirmed the lack of saturation with increasing dose and suggested the involvement of simple diffusion. In four dogs uptake fell from 4.76 +/- 6.8 to 40.4 +/- 8.2% (0.05 greater than P greater than 0.025) during partial occlusion of the pulmonary circulation by a Swan-Ganz catheter balloon and rose again to 51.2 +/- 6.4% after relief of the occlusion. Propranolol uptake, measured serially in five dogs with indwelling catheters, was initially 55% but fell linearly to 30% over 2 wk (r = -0.59, P less than 0.001), and necropsy showed pathological features of shock lung. A similar study performed on three dogs within 4 days of catheterization showed no change in uptake of the drug. Propranolol uptake appears to reflect both quantitative and qualitative changes in the pulmonary endothelium. This method may therefore be valuable in studying the pulmonary endothelium in health and disease.

Animals↗
PubMed1981

Changes in pH with age in Drosophila and the influence of buffers on longevity.

The pH of whole homogenates of Drosophila melanogaster declines from 7.44 during the first instar larval stage to 6.77 during the late pupal stage. In adult flies the pH declines from 6.92 to 6.70 with increasing age. Total carbonic anhydrase activity declines during the first 10 days of the adult stage. The carbonic anhydrase inhibitor acetazolamide failed to shorten life span. Low molecular weight buffers prolong the median life span when fed to flies in the pH range 7.0-8.3. The greatest prolongation occurs when the flies are given the buffers beginning at 2 weeks of age. 0.1 M HEPES (pH 7.5) increased life span by 22.9% and 0.01 M KHCO3 (pH 7.0) by 17.8%.

Aging↗
PubMed1981

First-pass lung uptake of propranolol enhanced in anaesthetized dogs.

Uptake of 14C-propranolol after a single passage through the pulmonary circulation was studied in three groups of Labrador dogs using a double indicator dilution method. Uptake in conscious, ambulant animals was 53%. This increased to 81% in dogs anaesthetized with thiopentone, nitrous oxide and halothane and to 64% in dogs anaesthetized with thiopentone, nitrous oxide and fentanyl. Interaction between lipid-soluble anaesthetic agents and pulmonary endothelial cell membranes may be an important factor in increasing lung uptake of lipophilic propranolol, although alteration in pulmonary perfusion associated with a reduction in cardiac output during general anaesthesia may play a part. The pharmacological effects of propranolol administered i.v. during general anaesthesia may be unpredictable.

Anesthesia, General↗
PubMed1980

Changes i superoxide dismutase activity and copper during development and ageing in the fruit fly Drosophila Melanogaster.

Total superoxide dismutase activity was found to increase during development of the fruit (Drosophila melanogaster) with an increase of 346% occurring between the larval and the one-day adult stage. During the adult stage total superoxide dismutase activity did not vary with age. Throughout the period of rapid increase in total superoxide dismutase there was a correspondingly rapid increase in total copper content. A continued increase in copper content during the adult stage suggested, however, that copper levels were not determining total superoxide dismutase activity during adult ageing. The cyanide-insensitive or mitochondrial superoxide dismutase reached a maximum at 8 days of age and decline by 21% between 8 and 58 days of age.

Aging↗
PubMed1980

Evaluation of the Datex CD-101 and Godart Capnograph Mark II infra-red carbon dioxide analysers.

Performance of the Datex CD-101 and Godart Capnograph Mark II infra-red carbon dioxide analysers was investigated. The Datex machine uses a solid-state infra-red detector, while the Godart instrument uses a Luft detector. Both instruments were easy to use and the small size and light weight of the Datex was an added convenience. Linearity, stability, response time and the effect of nitrous oxide were within specification in both machines except when 10% carbon dioxide was used with the Datex analyser. Linearity of the Godart instrument was considerably better than 1% full scale deflection (fsd) quoted in the specification, while the Datex analyser was within 2% fsd (4% fsd with 10% carbon dioxide).

Anesthesia, Inhalation↗
PubMed1980

Singlet oxygen and aging in Drosophila.

There was little or no improvement in the median survival times of Drosophila melanogaster fruit flies when fed high concentrations of the singlet oxygen quenchers, beta-carotene and 1,4-diazabicyclo(2.2.2)octane. Singlet oxygen was presumably generated endogenously by inactivating catalse with 3-amino-1,2,4-triazole and feeding NaOCl. This treatment caused reduction in median life span of from 14.3 to 25% depending upon the NaOCl concentration used. beta-Carotene and 1,4-diazabicyclo(2.2.2)octane gave partial protection against the singlet oxygen generated by NaOCl. These data are interpreted to mean that normally occurring singlet oxygen does not contribute to senescence in Drosophila but that artificially produced singlet oxygen accelerates the rate of aging.

Aging↗