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Biomedical subjects

D L Murphy

Publications and source records attributed to D L Murphy.

At least 541 records · Page 30Linked to original sources
PubMed1976

Platelet monamine oxidase in chronic schizophrenia. Some enzyme characteristics relevant to reduced activity.

To evaluate further the basis for the reduced activity of platelet monoamine oxidase (MAO) found in chronic schizophrenic patients, a number of characteristics of the enzyme were compared between patients and controls. Equivalent and statistically significant reductions in activity of the enzyme were found in the patients when tyramine and benzylamine were used as the substrates in comparison to previously reported reductions with tryptamine as the substrate. Michaelis constants for platelet MAO from chronic schizophrenic patients with reduced enzyme activity were not different from controls. Dialysis of the enzyme from patients and controls yielded no changes in activity. Studies of other platelet enzymes, including succinate dehydrogenase, cytochrome C reductase, and lactate dehydrogenase in patients, normal controls, and a subgroup of normal controls with reduced MAO activity, showed no parallel reductions in activity in patients or controls with low MAO activity. These findings suggest that the reduced MAO activity found in chronic schizophrenic patients is apparently not accounted for by nonspecific changes in platelets or platelet mitochondria.

Adult↗
PubMed1976

Neurobiological Considerations of the mode of action of lithium carbonate in the treatment of affective disorders?

The effects of lithium on membrane function and cellular processes are considered in relation to lithium's physiochemical properties. Several cellular regulatory functions, including cyclic AMP formation and metabolism and biogenic amine neurotransmitter metabolism, are examined as possible mechanisms whereby lithium might exert its mood stabilizing actions. The necessity for understanding lithium's interactions with "receptors" - the molecular sites affected by lithium - in considering its pre-and post-synapatic effects in stressed.

Affective Symptoms↗
PubMed1976

Electrophoresis of platelet monoamine oxidase in schizophrenia and manic-depressive illness.

Monoamine oxidase is an important enzyme in the catabolism of biogenic amines and can be measured in human platelets. Platelet MAO has been reported to be reduced in schizophrenic and manic-depressive patients, though other reports are contradictory. The present study evaluated the possibility that qualitative genetic enzyme abnormalities of MAO could be responsible for the different enzyme activities of platelet MAO in different populations. However, polyacrylamide gel electrophoresis of platelet MAO from 10 manic-depressive, 12 schizophrenic, and 11 normal individuals did not reveal any genetic mutant forms.

Adult↗
PubMed1976

Lithium does not inhibit the parathyroid hormone-mediated rise in urinary cyclic AMP and phosphate in humans.

To test the hypothesis that lithium is a general inhibitor of hormone-activated adenylate cyclase, we infuse parathyroid hormone (PTH) into human subjects prior to and during lithium carbonate administration. PTH infusion caused a significant increase in urinary cyclic AMP and urinary phosphate excretion. There was no significant difference in these responses in the lithium compared to the control period. In four patients with primary hyperparathyroidism, lithium had no significant effect on serum calcium or phosphate or on tubular reabsorption of phosphate. The data do not substantiate the hypothesis that lithium (at therapeutic concentrations) is a general inhibitor of hormonally-activated adenylate cyclase, nor do they support its potential clinical utility in primary hyperparthyroidism.

Adenylyl Cyclase Inhibitors↗
PubMed1976

Encoding-imagery specificity in alcohol state-dependent learning.

A free-recall procedure demonstrated state-dependent learning using alcohol. Tests of long-term memory showed that both high- and low-imagery words were less likely to be recalled if stored while intoxicated rather than under sober conditions. However, information encoded and stored while intoxicated was more effectively retrieved when later tests of recall were performed while intoxicated, as compared to recall accomplished in the sober state. This dissociative recall effect was far more robust with low-imagery than with high-imagery words.

Adult↗
PubMed1976

Urinary excretion of 3-methoxy-4-hydroxyphenylglycol in depressed patients: modifications by amphetamine and lithium.

The excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG), the urinary metabolite which may best reflect brain norepinephrine, was measured in eight depressed patients on a longitudinal basis during the administration of placebo, d- and 1-amphetamine (30 mg/day), lithium carbonate (0.9 - 2.1 g/day), and d- and 1-amphetamine together with lithium. d-Amphetamine significantly decreased MHPG excretion. No significant change in MHPG was observed during administration of 1-amphetamine or when d- or 1-amphetamine was given together with lithium carbonate. Six patients responded with behavioral activation and euphoria to d-amphetamine, and these patients tended to have lower base line MHPG values in comparison to the nonresponders. Reductions in MHPG excretion during amphetamine administration were greatest in the patients with minimal behavioral responses to the drug, while some of the patients demonstrating more marked stimulant effects had elevated levels of MHPG during the amphetamine administration period. Variable changes, including elevated levels of MHPG in the responders, might represent the contribution of amphetamine-related changes in clinical state, including increased physical activity and (in two of the responding patients) the development of hypomania.

Adult↗
PubMed1975

Attenuation of the euphoriant and activating effects of d- and l-amphetamine by lithium carbonate treatment.

Seven of nine depressed patients experienced a 4.3-fold increase in rated euphoria and activation following 30 mg d-amphetamine in a replicated dose, double blind study. d-Amphetamine was 2 to 2.3-fold more effective in producing activation, euphoria, and antidepressant effects than the same dose of l-amphetamine. Co-treatment with lithium carbonate produced a 60% (P less than 0.001) attenuation of the activation and euphoria responses to d-amphetamine. The responses to l-amphetamine were almost completely abolished by lithium. This study raises the possibility of lithium carbonate use as an adjunct in the treatment of amphetamine addiction.

Adult↗
PubMed1975

Perception and cognition in patients with bipolar and unipolar depressive disorders. A study in orschach responding.

The Rorschach was administered to 16 bipolar and 13 unipolar patients hospitalized during a depressive episode. Two contrasting styles of Rorschach responding differentiated the two patient groups. The bipolar style of response is characterized by selective attention to the more objective aspects of the inkblots, while the unipolar style of response is characterized by a more subjective approach. Primary response to color was found only in the protocols of bipolar patients. The styles of response were discussed in relation to other studies showing similar results based on self-assessment and clinical tests. It was suggested that perceptual-cognitive structuring of the external environment may be related to, or predispose, mood levels.

Adult↗