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Biomedical subjects

J M Donovan

Publications and source records attributed to J M Donovan.

64 records · Page 4Linked to original sources
PubMed1985

Influence of dilution on the physical state of model bile systems: NMR and quasi-elastic light-scattering investigations.

Multinuclear (1H and 31P) nuclear magnetic resonance (NMR) spectroscopy and quasi-elastic light scattering have been used to characterize molecular aggregates formed in dilute sodium taurocholate--egg lecithin solutions. When mixed micelles (1.25 g/dL) are diluted with 150 mM aqueous sodium chloride, light-scattering measurements suggest a transformation from mixed micelles to unilamellar vesicle species. Decreased 1H NMR line widths for bile salt resonances are consistent with predominance of a monomer form. The concurrent appearance of a second phospholipid choline methyl resonance indicates two types of phospholipid environment in slow chemical exchange: this behavior is consistent with small unilamellar vesicles. The appearance of bilayer vesicles in dilute model bile solutions is confirmed by addition of a lanthanide shift reagent (Pr3+), which splits the 1H or 31P head-group peak into two components with distinct chemical shift sensitivities. These mixed micelle and vesicle aggregates are also distinguished by their susceptibility to the lipolytic enzyme phospholipase A2 from cobra venom.

Bile↗
PubMed1985

Methyl branching in short-chain lecithins: are both chains important for effective phospholipase A2 activity?

Several seven-carbon fatty acyl lecithins with varied acyl chain branching have been synthesized and characterized as potential phospholipase A2 substrates. Micellar bis(4,4-dimethylpentanoyl) phosphatidylcholine, bis(5-methylhexanoyl)phosphatidylcholine, bis(3-methylhexanoyl)phosphatidylcholine, and bis(2-methylhexanoyl)phosphatidylcholine are poor substrates for phospholipase A2 (Naja naja naja). These branched lecithins also inhibit the hydrolysis of diheptanoylphosphatidylcholine by the enzyme with Ki values comparable to or smaller than the apparent Km of the linear compound. The terminally branched lecithins are excellent substrates for another surface-active hydrolytic enzyme, phospholipase C from Bacillus cereus. When only one acyl chain bears a methyl group, the hybrid lecithins 1-heptanoyl-2-(2-methylhexanoyl)phosphatidylcholine and 1-(3-methylhexanoyl)-2-heptanoylphosphatidylcholine are substrates comparable to diheptanoylphosphatidylcholine. Analysis of micellar structure and dynamics by 1H and 13C NMR spectroscopy, quasi-elastic light scattering, and comparison of critical micellar concentrations indicates little significant difference in the conformation and dynamics of these seven-carbon fatty acyl lecithin micelles, even when the methyl groups are adjacent to the carbonyls. Phospholipase A2 UV difference spectra induced by phospholipid binding imply different enzyme conformations or aggregation states caused by linear-chain and asymmetric-chain lipids compared to bis(methylhexanoyl)phosphatidylcholines. The differences in hydrolytic activity of phospholipase A2 against the branched-chain micellar lecithins can then be attributed to an enzyme-lipid interaction at the active site. The species with both fatty acyl chains branched bind to phospholipase A2 but are not turned over rapidly. Since poor enzymatic activity only occurs for lecithins with both chains methylated, the interaction of both chains with the enzyme must be important for catalytic efficiency.

Kinetics↗
PubMed1983

The treatment requests of alcoholics.

Two hundred and thirty-four alcoholic patients at a general hospital outpatient clinic were administered a questionnaire to ascertain their treatment requests. One year later information characterizing the patients and their treatment outcomes was obtained by chart review and therapists' ratings. The alcoholics' treatment requests were similar to those obtained previously with general psychiatric populations. The most frequent requests were for psychological treatments: 'clarification of issues' or 'psychodynamic insight' while requests for administrative help or social intervention were least frequent. Requesting psychological treatments did not significantly predict engaging in psychotherapy or change during therapy. Requesting help with the complications of drinking only and not psychological help predicted early drop out. Medical, administrative and social intervention requests predicted poor improvement in drinking behavior during therapy.

Adult↗
PubMed1979

The crisis group--an outcome study.

The authors describe the day-to-day functioning and outcome of an 8-session, active, crisis-oriented outpatient psychotherapy group. Symptoms of anxiety and depression improved significantly in participants of the crisis group; these changes were even more positive at 1-year follow-up. The authors speculate that the success of the crisis group can be attributed to the felicitous characteristics of the patients and to the group structure and function, which provided an excellent vehicle for crisis intervention management.

Adjustment Disorders↗
PubMed1975

Psychiatric crisis. A comparison of schizophrenic and nonschizophrenic patients.

Thirty-nine patients (23 nonschizophrenic and 16 schizophrenic people), who were hospitalized on a short term, crisis intervention ward, were extensively interviewed to discover whether the crisis precipitants and the crisis experience differed for the two groups. As opposed to the schizophrenic individuals, the nonschizophrenic, "distraught" patients led orderly lives and were more likely to be in problematic developmental life stages (i$, late adolescense) or to be physically ill. For the distraught patients, the precipitating events were clearer and were more likely to involve interpersonal or narcissistic loss (i.e., the end of a romance), overt anger was less likely to be expressed, and parental figures were less likely to be involved. Both the nonschizophrenic and the schizophrenic people were thought to be chronically vulnerable to external stress. A phenomenological description of their psychopathology was included to explain, in part, their vulnerability. Suggestions about treatment approaches were developed.

Adolescent↗