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Biomedical subjects

A Gibson

Publications and source records attributed to A Gibson.

At least 199 records · Page 11Linked to original sources
PubMed1976

Ovarian tumours in childhood: a 27-year review.

Twenty-five children treated for ovarian neoplasms at the Royal Hospital for Sick Children, Yorkhill,Glasgow, between 1947 and 1974 are reported. Eight of the patients had malignant tumours and 17 benign. The patients with benign tumours were treated by either salpingo-oophorectomy or oophorectomy. The malignant cases were treated with either surgery alone or in combination with deep X-ray therapy and/or chemotherapy. Two patients died of malignant teratoma, but the remaining 6 with malignant teratoma, dysgerminoma or endodermal sinus are well. The management of these patients is discussed.

Adolescent↗
PubMed1976

The possible involvement of Na+ ions in corticosterone-induced hypercontractility in the rat anococcygeus muscle.

The possibility that corticosterone-induced hypercontractility in the rat anococcygeus muscle might be due to an intramuscular redistribution of Na+ was investigated. 2 The contractility of the isolated muscle to noradrenaline (NA) was directly dependent on the Na+ concentration of the Krebs solution. 3 There was a linear relationship between the maximum contractile response of the muscle to NA and the Na+ concentration of the Krebs solution. 4 Muscle contractility was also increased by the presence of ouabain (10(-4)M) in the bathing medium. 5 Muscles from rats treated with corticosterone exhibited increases in both total and ouabain-sensitive ATPase activity. 6 The relationship between corticosterone, Na+ distribution, and muscle contractility is discussed.

Adenosine Triphosphatases↗
PubMed1976

Visual cells in the pontine nuclei of the cat.

Two hundred and thirty-two visually activated neurones were recorded in a small area of the rostral pontine nuclei of cats. The location of visually activated neurones was coextensive with the input from visual areas of cat's cortex as determined by degeneration studies. 2. Pontine visual cells could only be driven by visual stimuli. Cells responsive to somatosensory or auditory stimuli were also found in different regions in rostral pontine nuclei. They too responded to only one modality. 3. 96% of the cells were directionally selective. 4. Pontine visual cells were responsive to a wide range of stimulus speeds. Some cells responded to targets moving as fast as 1000 degrees/sec without losing directional selectivity. No pontine visual cells gave a clearly sustained response to a stationary stimulus. 5. Exact stimulus configurations were not critical. Large fields containing many spots were the most effective stimuli for 50% of the cells. Inhibition of responses depending upon stimulus dimensions, direction of movement, or location in the visual field was found for many cells. 6. Receptive field dimensions were large, ranging in size from 3 degrees X 4 degrees to more than an entire hemifield. 7. 94% of the cells had receptive fields which were centred in the contralateral hemifield. 8. 98% of the cells could be driven from both eyes. 9. The properties of the pontine visual cells suggest a corticopontocerebellar pathway sensitive to a wide range of speeds and directions of movement, but not sensitive to precise form.

Action Potentials↗
PubMed1975

Reduction in the cholinesterase activity of the rat anococcygeus muscle produced by corticosterone.

1 Administration of corticosterone caused a 47% reduction in the cholinesterase (ChE) activity of homogenates of the rat anococcygeus muscle. 2 ChE activity was also reduced by morphine withdrawal and this effect was abolished by the corticosteroid synthesis inhibitor, metyrapone. 3 A single dose of reserpine reduced ChE activity in normal but not in adrenalectomized rats. 4 ChE activity was increased by adrenalectomy or by metyrapone treatment. 5 The mechanism of the corticosteroid-induced reduction in ChE activity is discussed. 6 The reduction in ChE activity produced by corticosterone, morphine withdrawal, or a single dose of reserpine might explain the leftward shift of the dose-% response curve to acetylcholine produced by these procedures in the isolated anococcygeus muscle of the rat.

Adrenal Glands↗
PubMed1975

The involvement of corticosteroids in the supersensitivity produced in the rat anococcygeus muscle by morphine withdrawal, thyroidectomy or a single dose of reserpine.

The effects of chronically administered corticosterone on the responses of the rat isolated anococcygeus muscle to agonists (acetylcholine, norepinephrine) were compared with those of morphine withdrawal in intact or metyrapone-pretreated rats and with those of a single dose of reserpine in intact or adrenalectomized rats. The possibility that the similar supersensitivity, which occurs in thyroidectomized rats, might be associated with elevated corticosterone levels was investigated by measuring fluorimetrically the plasma levels of corticosterone in thyroidectomized rats. Corticosterone, morphine withdrawal or a single dose of reserpine produced similar supersensitivities, characterized by increased maximum responses to both agonists (acetylcholine, norepinephrine) and an increased pD2 value for acetylcholine. This effect of morphine withdrawal together with the weight loss characteristic of this condition was absent in metyrapone-pretreated rats. A single dose of reserpine had no effect in adrenalectomized rats. Plasma corticosterone levels were elevated in thyroidectomized rats. These results suggest that the common factor underlying the identical supersensitivities produced by corticosterone, morphine withdrawal, a single dose of reserpine or thyroidectomy is the ability of each treatment to raise plasma corticosterone levels.

Acetylcholine↗
PubMed1973

The effect of immunosympathectomy and of 6-hydroxydopamine on the responses of the rat anococcygeus to nerve stimulation and to some drugs.

1. The rat anococcygeus muscle possesses a dense motor adrenergic innervation and also a powerful inhibitory innervation whose transmitter is unknown. The possibility that the adrenergic nerves released both noradrenaline and the unknown inhibitory transmitter was investigated by destroying the adrenergic nerves either by immunosympathectomy or by 6-hydroxydopamine.2. Immunosympathectomy was only partially effective in destroying the adrenergic neurones to the anococcygeus. 6-Hydroxydopamine destroyed the terminal adrenergic varicosities abolishing almost completely the motor response. Neither treatment affected the inhibitory response.3. 6-Hydroxydopamine induced a specific hypersensitivity of the muscle to noradrenaline which was not shared with carbachol.4. The maximum tension response of the anococcygeus muscle was greater in the male than in the female probably because the muscle is bigger.

Anal Canal↗
PubMed1973

The effects of drugs on the sensitivity of the rat anococcygeus muscle to agonists.

1. The effects of cocaine, 6-hydroxydopamine (6-OHDA), reserpine and 17-beta-oestradiol on the sensitivity of the rat anococcygeus muscle to noradrenaline (NA), acetylcholine (ACh) and KCl were investigated.2. Cocaine (10(-5)M) increased the sensitivity of the anococcygeus to NA (100-fold) but not to ACh or KCl.3. 6-OHDA treatment, whether discontinuous over 6 days or continuous for 12 days, also produced a specific increase in sensitivity to NA (50-fold).4. Reserpine ((1 mg/kg)/day) produced a small increase in sensitivity of the muscle to NA and ACh but not to KCl, after 6 days and 12 days treatment.5. 17-beta-Oestradiol (10(-5)M) had no effect on the sensitivity of the anococcygeus to NA or ACh, but reduced the sensitivity to KCl and the possible mechanism of this effect is discussed.6. Cocaine increased, while reserpine, 6-OHDA and 17-beta-oestradiol decreased, the maximum response of the muscle to KCl. The response to KCl was shown to consist of at least three components; a direct action on the muscle, an effect due to release of NA, and an inhibitory action, probably due to release of the unknown inhibitory transmitter.

Acetylcholine↗