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Biomedical subjects

I R Cameron

Publications and source records attributed to I R Cameron.

At least 55 records · Page 3Linked to original sources
PubMed1982

Observations on lithium disposition in the elderly.

The disposition kinetics of lithium were studied in six elderly women who had been maintained on this medication for several years. Lithium administration was stopped abruptly. Plasma, whole blood, and erythrocyte half-lives were then measured, as well as renal plasma clearance and distribution volume. Half-life values in whole blood and in its components were found to be similar. The plasma lithium half-life approximated that in younger schizophrenics, but appeared prolonged when compared with half-lives reported for young normal volunteers. Renal plasma clearance and distribution volume of lithium appeared substantially reduced when compared with published values. The data are consistent with altered lithium disposition in the aged.

Affective Symptoms↗
PubMed1981

Effect of chronic dietary potassium depletion and repletion on cardiac and skeletal muscle structure, electrolytes and pH in the rabbit.

1. Chronic dietary potassium depletion which was severe enough to decrease skeletal muscle intracellular potassium concentration by 20%, did not significantly reduce cardiac intracellular potassium concentration of rabbits. 2. Chronic potassium depletion caused a fall in intracellular pH in skeletal muscle, but no changes occurred in cardiac intracellular pH. 3. Intracellular potassium was increased above normal after 1 week of potassium repletion, but had returned to normal after 3 weeks of repletion. This may have resulted from potassium retaining mechanisms which had developed during depletion and which persisted during the early stages of repletion. 4. Cardiac and skeletal muscle from potassium-depleted animals did not show any structural damage when examined by light and electron microscopy.

Animals↗
PubMed1978

Tandem integration of complete and defective SV40 genomes in mouse-human somatic cell hybrids.

We have analyzed the arrangement of SV40 DNA sequences integrated in human chromosome 7 in two lines of mouse-human somatic cell hybrids: one containing only one human chromosome 7 per cell and the other containing an average of about three. We found that the integration site differs in both the viral and host sequences in the two clones. However, the sites of integration into the several copies of human chromosome 7 of one clone are identical. Each chromosome 7 in both clones carries approximately six viral genomes tandemly linked. Some of these genomes lack about 20% of the DNA from the late region, including the Eco RI site.

Animals↗
PubMed1977

Role of Pco2 oscillations and chemoreceptors in ventilatory response to inhaled and infused CO2.

We have previously shown in the anaesthetized rabbit that the ventilatory response to an increase in Paco2 is greater if that increase is produced by intravenous infusion of hypercapnic blood than by inhalation of CO2 (Linton et al., 1976). The present set of experiments was designed to investigate the reason for this. It was found that the difference in ventilatory response observed in the intact rabbit was abolished by cutting the carotid sinus nerves or by eliminating the pH/Paco2 oscillations in the carotid blood flow. It is concluded that the normally greater ventilatory response to intravenous infusion of hypercapnic blood compared with inhalation of CO2 is due to a respiratory signal derived from Paco2 oscillations and carried in the carotid sinus nerves.

Animals↗
PubMed1977

The effect of chronic frusemide administration on intracellular potassium, sodium and pH of cardiac and skeletal muscle.

1. Chronic administration of frusemide in large doses of 4 mg day-1 kg-1 for 3 weeks caused a significant reduction of cell water in rabbit cardiac and skeletal muscle. Intracellular Na+ concentration, intracellular pH and extracellular space was unchanged in both tissues. Intracellular K+ concentration increased slightly in both cardiac and skeletal muscle. 2. It is concluded that frusemide does not reduce intracellular K+ concentration in cardiac or skeletal muscle of normal animals receiving a normal oral potassium intake.

Animals↗
PubMed1976

Ventilatory response to CO2 inhalation and intravenous infusion of hypercapnic blood.

The ventilatory responses to intravenous infusion of hypercapnic blood (equilibrated with 80% CO2: 20% O2) and inhaled CO2 (1.5-2.0% CO2) have been compared in anaesthetized rabbits. A control infusion of blood equilibrated with 4% CO2: 21% O2 produced no change in V, PaCO2 or PaO2. The ventilatory response to a given rise in PaCO2, deltaV - (delta PaCO2)-1, was greater during infusion of hypercapnic blood (69 +/- 33 ml-min-1-mm Hg-1, mean +/- SD) than during CO2 inhalation (28 +/- 16 ml-min-1-min Hg-1, P less than 0.01). There was no difference between the rates at which the final levels of ventilation were reached during inhalation of CO2 or infusion of hypercapnic blood. It is suggested that the difference between the responses may be accounted for by differences in the pattern of PaCO2 oscillations in the two situations.

Animals↗
PubMed1976

The effect of local changes in potassium and bicarbonate concentration on hypothalamic blood flow in the rabbit.

Blood flow has been measured locally in the hypothalamus of anaesthetized rabbits by measuring the clearance of small volumes (5-20 mul.) of a mock cerebrospinal fluid solution containing 133Xe. The effect of varying the [K+] or [HCO-3] of the 133Xe-containing solution on local hypothalamic blood flow has been investigated. 2. There was an increase in local hypothalamic blood flow if the 133Xe-containing solution was HCO3--free; raising the [HCO--3,] of the solution to 40 mM caused a fall in local blood flow. 3. There was an increase in local hypothalamic blood flow when 133Xe was injectedin a mock cerebrospinal fluid containing 10 or 20 mM-[K+]. There was no significant change in blood flow if a K+-free or a 40 mM [K+] solution was used. 4. The decrease in hypothalamic blood flow caused by injecting a 40 mM-[HCO3] solution could be reversed by the addition of 20 mM [K+] to the solution. There was no further increase in blood flow if 20 mM-[K+] was added to a HCO3--free solution. 5. It is concluded that local blood flow in the hypothalamus changes as a result of variation in local [K+] as well as local [HCO-3]. The changes in blood flow in the brain which accompany neuronal activity could be mediated by variation in local [K+].

Animals↗
PubMed1976

Small airways in fibrosing alveolitis.

Pulmonary function, including lung elastic recoil, was measured in 9 subjects with fibrosing alveolitis. Closing volume and upstream conductance were studied to assess small airway function. Lung volumes, diffusing capacity, and transfer coefficient were decreased. Peak expiratory flow and the ratio of 1-sec forced expiratory volume to forced vital capacity were normal, whereas total lung resistance was low, suggesting that large airways were not narrowed. Lung elastic recoil was increased, but the changes could be accounted for by the loss of lung volume. Closing volume and closing capacity were increased when expressed as a percentage of vital capacity and total lung capacity, respectively; but again, this could be accounted for by the decrease in lung volume, because the absolute lung volume at which airway closure occurred was normal. Upstream conductance was not reduced. We conclude that there is no evidence of narrowing of functional small airways in ventilated parts of the lung. The mechanical findings are compatible with the patchy involvement seen pathologically in fibrosing alveolitis.

Adult↗