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Biomedical subjects

B A Goodman

Publications and source records attributed to B A Goodman.

26 records · Page 2Linked to original sources
PubMed1988

Spin trapping of free radicals in homogenates of heart from selenium and vitamin E deficient rats.

The formation of unstable free radical species in homogenates of heart from selenium and/or vitamin E deficient rats has been investigated by electron spin resonance spectroscopy using the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone. There was only a small amount of free radical formation by heart from control or selenium deficient animals. However, the amounts and rates of formation of free radicals were significantly higher in animals with vitamin E deficiency and higher still in those with combined selenium and vitamin E deficiency.

Animals↗
PubMed1988

The influence of dietary history on the production of free radicals in rat liver microsomes.

Free radicals have been trapped in microsomal fractions from rat livers by the use of alpha-(4-pyridyl-l-oxide)-N-tert-butylnitrone (4-POBN) and detected by ESR spectroscopy. Using this technique we have investigated the effects of low dietary concentrations of vitamin E and selenium (Se) on free radical production. When the microsomal fractions were incubated with Fe, ADP and NADPH significantly greater amounts of radicals were initially trapped when rats were deficient in vitamin E (whether combined with Se deficiency or not) than from Se-deficient animals or Se- and vitamin E-supplemented controls. After prolonged incubation (ca. 30-45 mins) the free radicals trapped from the microsomes from the Se-deficient animals rose to amounts comparable to those seen in the vitamin E-deficient microsomes. Over the same period of incubation approximately half this quantity of radicals were trapped in liver microsomes from Se- and vitamin E-supplemented rats. The effects of 4-POBN on the levels of peroxidation in the various microsomal fractions were assessed by measuring the thiobarbituric acid reactive substances (TBARS). The presence of 4-POBN significantly reduced the amounts of TBARS formed on incubation and there was a clear distinction between the groups on the basis of the vitamin E status of their diets.

Animals↗
PubMed1986

Oxygen-induced free radical in wheat roots.

ESR experiments have shown that free radicals are formed in wheat plant roots as a result of exposure to O2. Although the radical(s) has not been positively identified, the nature of the spectra allows simple oxygen-derived radicals, such as O2-, HO2. and OH., to be excluded as possibilities. Adsorption of Cu(II), but not Zn(II) or Cd(II) by the root results in a rapid decay of the radical signal to reach a level of 10% of its original intensity after a few minutes.

Electron Spin Resonance Spectroscopy↗
PubMed1985

The occurrence of copper, iron, zinc and other elements and the nature of some copper and iron complexes in humic substances from municipal refuse disposed of in a landfill.

Municipal refuse was allowed to decompose in a simulated landfill for 20 months. Three different models were studied in which the refuse, in 40 m3 lots, was either compacted or mixed 2:1 with sewage sludge, the latter being studied in both uncompacted and compacted states. At 2, 6, 12 and 20 months, humic substances were extracted from samples with 0.1 M Na2P4O7 and 0.1 M NaOH, and humic acids isolated by precipitation after acidification with HCl. The humic substances were examined by electron paramagnetic resonance (EPR) to determine the free radical content and the nature of some of the metal complexes present. The principal form of copper was present in either a square planar or a tetragonally-distorted octahedral environment, probably coordinated to two nitrogen and two oxygen atoms. Fe3+ was present in at least three different environments. In one, it was probably in a complex with rhombic symmetry; another showed Fe3+ in an axially-symmetric environment, most likely as a ferric porphyrin. No distinctions could be made between the concentrations or forms of metals present in the refuse humic substances as a result of adding sewage sludge, but the additions increased the yield of humic substances, particularly in the uncompacted landfill. Humic substances in the refuse retain metal elements in complexed forms which will restrict their release from the landfill.

Carbon↗
PubMed1974

Cardiac responses to snout immersion in trained dogs.

1. Four dogs were trained to immerse their snout voluntarily for durations up to 30 sec. Indwelling instrumentation was implanted to measure blood flow velocity in the circumflex branch of the left coronary artery, to sample blood from the left atrium and coronary sinus for the determination of P(O2), P(CO2), pH, oxygen saturation and haemoglobin concentration, and to pace the heart. An index of myocardial oxygen consumption was calculated by multiplying the mean flow velocity by the arteriovenous difference in oxygen content.2. Mean coronary flow velocity decreased significantly during simulated diving by 26 +/- 27% (+/- S.D.). The range of decrease in seventeen out of twenty experiments was from -5 to -81%. Heart rate decreased by 48 +/- 7% and this bradycardia was abolished by I.V. atropine.3. Coronary sinus oxygen saturation increased significantly with snout immersion (three dogs) and arteriovenous difference decreased from 67 +/- 10 to 47 +/- 5%. The index of myocardial oxygen consumption decreased by 42 +/- 19%. This decrease was attenuated slightly by beta-blockade but was abolished by cardiac pacing in three out of four experiments.4. The present study indicates that the heart consumes oxygen at a considerably reduced rate during simulated diving and therefore plays a direct role in the overall conservation of oxygen. This response appears to result primarily from a negative chronotropic effect induced by increased vagal tone.

Animals↗