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Biomedical subjects

M Wallace

Publications and source records attributed to M Wallace.

At least 181 records · Page 10Linked to original sources
PubMed1983

Hormonal regulation of phosphatidylinositol breakdown.

Cyclic AMP and Ca2+ are intracellular mediators of hormone action. Catecholamines interact with beta adrenoceptors to activate adenylate cyclase or with alpha 2 adrenoceptors to inhibit adenylate cyclase. Alpha 1 adrenoceptor activation results in elevation of cytosol Ca2+ and an increased breakdown of phosphatidylinositol. In blowfly salivary glands, 5-hydroxytryptamine (5-HT) interacts with beta type receptors resulting in adenylate cyclase activation while alpha type receptors are involved in phosphatidylinositol breakdown and elevation of cytosol Ca2+. The link between Ca2+ mobilization and phosphatidylinositol breakdown remains to be established but breakdown of the receptor-regulated pool of phosphatidylinositol is not secondary to the rise in Ca2+. Direct addition of 5-HT to cell-free homogenates of blowfly salivary glands results in activation of phosphatidylinositol breakdown in the absence of Ca2+. In rat liver plasma membrane preparations, vasopressin increases phosphatidylinositol breakdown in the absence of Ca2+ or cytosol if deoxycholate is present. The data do not indicate whether hormone activation increases the availability of substrate to enzymatic hydrolysis or activates phospholipase C. However, they demonstrate that hormones directly accelerate phosphatidylinositol breakdown.

Animals↗
PubMed1983

Effect of Co-dergocrine mesylate on tardive dyskinesia. A preliminary report.

Twenty patients with signs of tardive dyskinesia secondary to antipsychotic medication participated in a double blind, controlled, parallel group study comparing codergocrine mesylate 4.5 mg once daily with a placebo. After 6 weeks medication a reduction in dyskinetic scores occurred in both groups, but at the end of a further 6-week period the patients on active treatment maintained their improvement while those on placebo did not. This may be due to a slow onset of action and a hangover of activity associated with the drug.

Aged↗
PubMed1983

The effect of 6-OHDA lesions of the nucleus accumbens septum on schedule-induced drinking, wheelrunning and corticosterone levels in the rat.

In a series of four experiments the relationship between 6-OHDA lesions of the nucleus accumbens septum (NAS), schedule-induced behaviors and plasma corticosterone levels was explored. Data from the first experiment show a significant decrease in water intake during a scheduled food delivery test hour for 6-OHDA lesioned groups of rats compared with sham or non-lesioned groups of rats, while during the remaining 23 hours of the day water intake was the same for 6-OHDA lesioned and sham lesioned groups. In a second experiment similar decreases in schedule-induced wheelrunning were observed for 6-OHDA lesioned rats when compared with sham lesioned rats. Data from a third experiment showed significant increases in plasma corticosterone levels of rats in the presence of a scheduled food delivery compared with rats given non-scheduled food. In a fourth experiment it was shown that 6-OHDA lesions of the NAS abolish this increase of corticosterone levels in rats on a food delivery schedule. These data extend the findings of Robbins and Koob [19] and show a more general involvement of the dopaminergic pathways of the NAS in schedule-induced behaviors and in concomitant plasma corticosterone changes.

Animals↗
PubMed1983

A reinterpretation of schedule-induced behaviors based on a systematic analysis of behavior.

Confusion exists regarding the criteria to be used in determining whether or not particular behaviors are schedule-induced. Four critical characteristics of schedule-induced behaviors are suggested and a comparison made of the complete range of behaviors exhibited by body weight-reduced rats drinking in response to one of three stimuli. These were (1) a fixed-time food reinforcement schedule, (2) a meal of dry food, and (3) 24 hour water deprivation. Drinking, locomotion, rearing and oral and perioral behaviors occurred in accordance with the defining characteristics of schedule-induced behaviors. Rats in the fixed-time reinforcement condition also deposited significantly greater numbers of fecal boli. Sniffing and food bowl related behaviors occurred as terminal responses for this group. It is concluded that animals which receive reinforcers intermittently maintain high levels of arousal for extended periods, and that the presence of the schedule may mimic conditions experienced by wild rats in non-laboratory settings. In such conditions ambulatory behaviors may be particularly adaptive. In contrast, reinforcing sensory feedback and a stress reducing role may be particularly important in the mediation of oral behaviors (such as drinking) which occur during intermittent reinforcement.

Animals↗
PubMed1983

Changes in body weight and food-related behaviour induced by destruction of the ventral or dorsal noradrenergic bundle in the rat.

Three experiments contrasted the effects of 6-hydroxydopamine-induced lesions of the ventral noradrenergic and dorsal noradrenergic projections, predominantly to hypothalamus and cortex, respectively, upon body weight changes and food-related behaviour in the rat. In general, ventral noradrenergic bundle lesions enhanced weight gain and these effects were exaggerated by the provision of palatable cheese to the standard chow diet. In contrast, lesions of the dorsal noradrenergic bundle produced minor changes in body weight. Associated with the effects of ventral noradrenergic bundle lesions were hyperphagia, enhanced suppression of intake of food adulterated with quinine, (at high concentration), a small attenuation of food neophobia, and enhanced acquisition, but not performance, of the eating response to tail-pinch stimulation. These ventral noradrenergic bundle lesions failed to alter basal activity levels, amphetamine anorexia or the diurnal pattern of eating or activity. In contrast, lesions of the dorsal noradrenergic bundle did not produce either hyperphagia or enhanced rejection of food adulterated with quinine. However, there was a strong attenuation of food neophobia and a retarded acquisition (but unimpaired performance) of eating in response to tail-pinch stimulation. The results are discussed in connection with previous studies of ventral and dorsal noradrenergic bundle lesions, with the effects of ventromedial hypothalamic lesions and with the underlying behavioural and physiological processes that mediate these contrasting effects of different neuroanatomical patterns of central noradrenaline depletion.

Animals↗
PubMed1983

Improved utilization of blood for elective surgery.

Results of our experience have shown that SSBO and T & S are cost effective and extremely safe. We believe that the safety in using these guidelines for hemotherapy for elective surgery depends upon a sensitive and meticulously performed T & S, a mechanism by which ABO compatibility can be affirmed and an ongoing surveillance program to monitor the proper operation of these procedures.

Blood Grouping and Crossmatching↗
PubMed1982

Hospital staffing.

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Medical Staff, Hospital↗
PubMed1982

Effects of dopaminergic nucleus accumbens lesions on the acquisition of schedule induced self injection of nicotine in the rat.

Data from recent experiments show that dopaminergic depletion of the nucleus accumbens septum (NAS) decreases the frequency of schedule induced drinking and wheel running. In the present experiment a group of 8 rats with 6-OHDA lesions in the NAS showed a significantly lower rate of schedule induced nicotine self injection than sham operated controls. These findings extend the number of schedule induced behaviors which appear to depend for their occurrence on an intact dopamine system in the NAS.

Animals↗
PubMed1982

Schedule-induced self-injection of drugs.

Studies of acquisition and maintenance patterns of drug intake, including dependence, necessitate voluntary intake of drugs. Voluntary intake in animal studies is difficult to achieve because of aversive taste factors associated with most drugs, and involuntary or forced choice methods obscure the behavior which is the object of study. The schedule-induced polydipsia paradigm has been used to induce oral ingestion of large volumes of alcohol, barbiturate and other drug solutions. We have developed a method of schedule-induced self-injection which allows the study of acquisition and maintenance of drug intake behavior with changing environments free from the interference of taste factors or imbalances due to excessive water intake. In this paper we review our findings on the acquisition and maintenance patterns of amphetamine, methadone, heroin, alcohol, nicotine, cocaine, delta 9-THC and haloperidol. For all drugs except amphetamine, the combination of schedule and nutritional deprivation leads to the highest rates of drug intake as compared to controls. The schedule does not appear to be a potent factor at 90% and free feeding weight, and drug intake is the result of interaction of environmental factors and pharmacological properties of the drugs, rather than the effects of drug or environmental factors separately. The maintenance patterns of nicotine, cocaine, heroin and alcohol are also discussed and the advantages of schedule-induced self-injection over schedule-induced polydipsia methods are presented.

Amphetamine↗
PubMed1982

Foot shock analgesia. Lack of correlation with pituitary and plasma immunoreactive-beta-endorphin.

Effects of inescapable foot shock on pain threshold and on levels of immunoreactive beta-endorphin (ir-beta EP) in anterior pituitary, neuro-intermediate lobe and plasma were determined by hot plate test and radioimmunoassay respectively. Whereas handling and conditioned stress failed to alter baseline pain threshold, 20 min inescapable foot shock produced modest and transient analgesia. Levels of plasma ir-beta EP and corticosterone were significantly and concurrently raised by all treatments and remained elevated 40 min after foot shock. Changes in plasma levels of ir-beta EP and corticosterone were found to parallel one another but did not correlate with changes in pain threshold. AP content of ir-beta EP was significantly reduced 60 min after the cessation of inescapable foot shock, and N-IL content from 20 min after. The findings suggest that (i) plasma levels of ir-beta EP and corticosterone do not reflect changes in pain threshold, and (ii) ir-beta EP levels in anterior pituitary, neurointermediate lobe and plasma probably are not causally related to foot shock analgesia.

Analgesia↗
PubMed1981

Naloxone, adrenalectomy, and steroid replacement: evidence against a role for circulating beta-endorphin in food intake.

Naloxone has a dose-dependent, significant anorectic effect when administered to normal rats, consistent with an antagonism of central or peripheral enkephalinergic or endorphinergic mechanisms. Mean levels of circulating immunoreactive beta-endorphin were similar in intact rats (0.5 ng/ml) and dexamethasone-treated adrenalectomized rats (0.5 ng/ml). In contrast, plasma levels were high in adrenalectomized rats with no replacement steroid (1.3 ng/ml) and in adrenalectomized rats given the mineralocorticoid deoxycorticosterone (0.9 ng/ml). In sharp distinction to the clear changes in circulating immunoreactive beta-endorphin produced by adrenalectomy and selective steroid replacement, no differences were seen in baseline food intake or anorectic response to naloxone. We conclude that a physiological role for circulating beta-endorphin in the regulation of food intake appears unlikely.

Adrenal Cortex Hormones↗