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Biomedical subjects

A Drake

Publications and source records attributed to A Drake.

27 records · Page 2Linked to original sources
PubMed1986

Characterization of haem disorder by circular dichroism.

Native and reconstituted myoglobin were prepared and their c.d. spectra recorded in the Soret region. Time-dependent changes in dichroism following reconstitution were observed and related to haem orientational disorder. Comparative c.d. studies, in agreement with n.m.r. studies, reveal that the degree and nature of this disorder are species-dependent.

Circular Dichroism↗
PubMed1986

The cordycepin analogue of 2,5A and its threo isomer. Chemical synthesis, conformation and biological activity.

A new synthesis of the cordycepin analogue of 2,5A and its threo isomer is reported along with an assessment of their conformations by circular dichroism spectroscopy. Evidence is also presented showing that these compounds are stable against 2,5A-specific phosphodiesterase and are not able to activate the 2,5A-dependent endoribonuclease, possibly due to a reduced binding to the latter enzyme as compared to that of 2,5A.

Circular Dichroism↗
PubMed1981

The role of the cardiac nerves in regulation of sodium excretion in conscious dogs.

Conscious, chronically instrumented dogs, maintained on a high sodium intake, were used to investigate whether surgical cardiac denervation impairs the natriuresis associated with left atrial pressure increase produced in three ways: during an increase in left atrial pressure by means of a reversible mitral stenosis (protocol 1); after an i.v. saline load (1.0 ml 0.9% saline min-1 . kg-1 over 60 min) (protocol 2); after an oral saline load (14.5 mmol Na . kg-1 given with the food as isotonic solution) (protocol 3). During a reversible mitral stenosis, in intact dogs, urine volume and sodium excretion increased markedly (from 34--145 microliters . min-1 . kg-1 and from 3--12 mumol . min-1 . kg-1); mean arterial pressure increased by an average of 2 kPa (15 mm Hg) and heart rate by 53 b/min; plasma renin activity fell from 0.37--0.21 ng AI . ml-1 . h-1 . Cardiac denervation eliminated these effects of left atrial distension except for a small increase in heart rate (12 b/min). This indicates that the natriuresis and diuresis during left atrial distension resulted from stimulation of receptors located in the left atrium. In contrast, during protocol 2 and 3, the same amounts of sodium and water were excreted in the cardiac denervated dogs as compared to the intact dogs. A comparable decrease in plasma renin activity also was observed. -- Apparently the presence of the cardiac nerves is not a prerequisite for maintenance of sodium and water homeostasis.

Animals↗
PubMed1981

Alteration of aminoglycoside antibiotic ototoxicity by hyper- and hypohydration.

The ototoxicities of tobramycin sulfate and gentamicin sulfate were investigated in guinea pigs under conditions of normal, increased, and decreased hydration. Increased hydration was associated with no decline in the amplitude of the cochlear microphonics, a lesser decline in the eighth nerve action potentials and lesser damage to the organ of Corti. Decreased hydration was associated with an increase in the threshold of the cochlear microphonics and the eighth nerve action potentials, a decline in the amplitude of the cochlear microphonics, a greater decline in the eighth nerve action potentials, and greater damage to the organ of Corti. Tobramycin sulfate was substantially less toxic than gentamicin sulfate with normal, increased and decreased hydration. These findings suggest the preferential use of tobramycin sulfate for patients with normal renal function, and especially patients with renal impairment.

Action Potentials↗
PubMedDate not supplied

Alteration of aminoglycoside antibiotic ototoxicity: effect of semistarvation.

The effect of semistarvation on the toxicity and ototoxicity of tobramycin sulfate (TO) and gentamicin sulfate (GE) was investigated in guinea pigs by electrophysiological and histopathological methods. The presented data has shown that the toxicity and ototoxicity of aminoglycoside antibiotics is substantially increased when guinea pigs were semistarved. Our results should also warn researchers using semistarvation in their conditioning experiments which investigate the toxicity of different chemicals. Toxicity was greater in GE- than TO-treated animals, which caused the GE-treated animals to die during treatment or shortly after treatment. Thus, TO should be preferentially used because it has been shown to be less toxic and ototoxic in normal and altered nutritional conditions.

Animals↗