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Biomedical subjects

D L Murphy

Publications and source records attributed to D L Murphy.

At least 487 records · Page 27Linked to original sources
PubMed1979

Psychological characteristics corresponding to low versus high platelet monoamine oxidase activity.

From an original sample of 375 college students and employees studied for platelet MAO activity, 66 subjects representing the lower and upper deciles of the sample were contacted for further study, including administration of the booklet form of the MMPI. We analyzed what psychological characteristics might be associated with differences in MAO activity and attempted to cross-validate these characteristics by using them to predict the separability of low vs. high MAO subjects. Each subject was randomly assigned to one of two groups in which the low and high MAO subjects were balanced for sex. For 16 women in group A, a MAO scale discriminated low and high subjects with 100% accuracy. For 18 men in group A, a separate MAO scale discriminated with 94% accuracy. To cross-validate these results, the two scales were applied to another population; both discriminated low and high MAO women and men with a combined 97% accuracy. The thematic content of the two scales is discussed in the light of other reports on the psychological characteristics of low and high MAO subjects, including the apparent relationship between the scale content and the clinical features of bipolar affective disorder.

Adolescent↗
PubMed1978

Monoamine oxidase activity in different density gradient fractions of human platelets.

Monoamine oxidase (MAO) activity measured in human platelets is reportedly altered by such drugs as epinephrine, lithium carbonate, and imipramine, and also reduced in a number of clinical disorders. To evaluate whether MAO activity might differ in platelet subpopulations, density gradient centrifugation with arabino-galactan was used to prepare four platelet fractions that differed in weight and volume. MAO activity in the lightest and smallest platelet subpopulation was approximately one-half that in the heaviest and largest subpopulation. Because platelet weight and size are thought to be related to platelet age, it is possible that some drug effects on platelet MAO activity might represent changes in platelet turnover. Factors other than platelet turnover rates may contribute to individual differences in platelet MAO activity, however, since one group of individuals with markedly reduced platelet MAO activity exhibited no shift in the proportion of lighter versus heavier platelets nor in the relative amount of MAO activity in each density gradient subfraction.

Blood Platelets↗
PubMed1978

Are paranoid schizophrenics biologically different from other schizophrenics?

Two studies were undertaken to verify the presence of lowered platelet monoamine oxidase activity in chronic schizophrenia. In the first study, a retrospective chart analysis, the mean platelet activity of patients with chronic schizophrenia (7.73+/-0.64 nmol of benzylaldehyde product per 10(8) platelets per hour [S.E.M.]) differed significantly from that of normal controls (12.13+/-0.2, P less than 0.001). Chronic paranoid schizophrenics (4.81+/-0.46) differed significantly from chronic nonparanoid schizophrenics (8.6+/-0.75, P less than 0.03). A separate prospective study confirmed significantly lower values for monoamine oxidase activity in chronic schizophrenic patients diagnosed as paranoid (5.97+/-1.17) or as having secondary paranoid features (6.28+/-0.71) as compared to chronic nonparanoid schizophrenics (9.81+/-0.87, P less than 0.001). Chronic paranoid schizophrenia may be a separate disorder from the other chronic forms of schizophrenia, and this difference may be related, at least in part, to biochemical characteristics.

Blood Platelets↗
PubMed1978

Primary affective disorder: anxiety in unipolar and bipolar depressed groups.

A group of 50 patients (29 bipolar and 21 unipolar) hospitalized for depression were compared on the IPAT Anxiety Scale. The bipolar depressed group reported significantly less anxiety than the unipolar group. This finding supports the results of other studies that reported relatively less psychopathology in bipolar groups during the acute depressive state. It is suggested that test-taking defensiveness, especially denial, might account for relatively lower anxiety and MMPI scores in bipolar groups.

Anxiety↗
PubMed1978

Drug response and psychiatric nosology.

The possibility that pharmacological response might help to refine psychiatric nosology has been the subject of recurrent speculation, but few clear-cut results have been obtained. Only bipolar depressives and several other minor patient subgroups manifest consistent drug responses in association with characteristic psychobiological features. The presence of multiple intervening variables, such as individual differences in drug metabolism, drug-taking behaviour and biological sensitivity to drugs, may mitigate against the reliable identification of clinically distinguishable drug-responding subgroups. Futhermore, the majority of available psychoactive drugs have either multiple or broad spectrum effects inconsistent with hypotheses utilizing the mechanism or site of drug action to argue for a diagnosis-specific biological disorder at such sites. Nonetheless, the successful use of drug-response models in other areas of medicine suggests a rationale for continued exploration in this area, and a number of recent advances make this approach potentially more productive. Pharmacological developments have rendered it possible to assess the biological availability of drugs in potential responders, thus eliminating some of the confounding intervening variables. Further consideration should also be given to the use of drugs with more specific neurochemical effects, even when they themselves are not necessarily therapeutic. The comparison of drug responder and non-responder group has also been made more meaningful by the availability of more reliable methods of assessing clinical phenomena, more sophisticated diagnostic models and the introduction of other biological measures. Combining several of these approaches may allow the use of one to validate the other.

Antidepressive Agents, Tricyclic↗
PubMed1978

Psychological correlates of monoamine oxidase activity in normals.

This study replicates and extends earlier work by finding that low levels of platelet monoamine oxidase (MAO) activity correlate with sensation seeking, high ego strength, positive affect, and high leisure time activity levels, somewhat similar psychological correlates also being found for plasma amine oxidase activity. Although there are several ways in which a schizophrenia/MAO relationship may exist and still be congruent with the present data, these results pose difficulties for theories which link low MAO activity levels specifically to schizophrenia. Nothing in the present findings, however, is incongruent with the possibility of an association between low platelet MAO activity and bipolar affective disorder.

Adult↗
PubMed1978

Platelet monoamine oxidase in chronic schizophrenic patients.

The authors investigated platelet monoamine (MAO) activity in 40 chronic schizophrenic patients, 55 normal control subjects, and 16 hospitalized control subjects. The mean platelet MAO activity for the chronic schizophrenic patients was significantly lower than the mean in either control group. There were no significant differences between the mean platelet MAO activities in 21 chronic paranoid schizophrenic patients compared with 18 chronic undifferentiated schizophrenic patients.

Adult↗