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Biomedical subjects

G C Davis

Publications and source records attributed to G C Davis.

At least 91 records · Page 5Linked to original sources
PubMed1979

Chronic Parkinsonism secondary to intravenous injection of meperidine analogues.

Abuse of 4-propyloxy-4-phenyl-N-methylpiperidine, a meperidine congener, produced parkinsonism in a 23-year-old man. Unlike other drug-induced motor disturbances, the syndrome persisted for 18 months and responded to drugs that stimulate dopamine receptors. Biogenic amines and metabolites in the cerebrospinal fluid and microscopic evaluation of the brain at necropsy were consistent with damage to aminergic neurons in the substantia nigra.

Adult↗
PubMed1979

Analgesia to pain stimuli in schizophrenics and its reversal by naltrexone.

Psychophysical pain ratings and somatosensory evoked potentials (EPs) were studied in 17 off-medication patients with schizophrenia and 17 age- and sex-matched normal controls. Five of the 17 schizophrenic patients also participated in a clinical trial of naltrexone. In comparison with normal controls, schizophrenic patients were significantly more insensitive to painful stimulation (based on nonparametric analogues of d'from signal detection analysis) and had significantly smaller somatosensory EPs to painful stimuli. Schizophreniucs treated with naltrexone showed significant increases in EP amplitude at higher stimulus intensities and hyperalgesic effects on pain ratings.

Adult↗
PubMed1979

Research in endorphins and schizophrenia.

It has been suggested that the newly discovered endogenous opiate peptides (called endorphins) might play a role in the symptoms of schizophrenia. The administration of narcotic antagonists provides both a test of the hypothesis and a potential treatment. In this article, we review the methods by which data have been gathered to test endorphin involvement in schizophrenia. Alternative strategies, which hold greater promise of producing conclusive positive or negative evidence, include exploitation of individual differences, use of psychophysiological measures, genetic strategies, and multivariate statistical techniques with larger sample sizes.

Antipsychotic Agents↗
PubMed1979

Analgesia to painful stimuli in affective illness.

Patients with bipolar and unipolar affective illness (N = 76) were compared with 48 control subjects on a psychophysical pain rating procedure using both threshold and signal detection analysis. Affectively ill patients were more analgesic than controls, and depressed men were significantly more analgesic than depressed women or control subjects. Bipolar men showed a different pattern of analgesia than unipolar patients. Pain appreciation in depressed patients may be related to endogenous opiate-like substances; this could be assessed in narcotic antagonist studies of pain-tolerant depressed subjects.

Adult↗
PubMed1977

Intravenous naloxone administration in schizophrenia and affective illness.

Fourteen schizophrenic patients and five patients with affective disorders were given naloxone (0.4 to 10 milligrams) or placebo intravenously in a double-blind fashion. Physicians' ratings of hallucinations, mannerisms and posturing, conceptual disorganization, psychosis, and mood did not change significantly. A single item, unusual thought content, improved significantly on the naloxone day compared to the placebo day. There was no improvement in mood in affectively ill patients rated either by themselves or by physicians. Naloxone did not markedly improve any patient studied, which suggests that the acute blockade of opiate receptors is not associated with global improvement in psychotic symptomatology.

Adolescent↗
PubMed1977

The effect of total peripheral resistance on indicator-dilution curves from the central circulation of the dog.

The influence of total peripheral resistance on the dispersion of indicator particles passing through the central circulation was studied in five dogs. The standard deviation of indocyanine green indicator-dilution curves provided a measure of dispersion. The peripheral vascular resistance of the dog was altered during the experiment by the intravenous administration of sodium nitroprusside and methoxamine. We calculated the area of each curve by fitting the first portion of the curve to a random walk function and the cardiac output and the total peripheral resistance were calculated in the usual manner. The mean, standard deviation and area of each of the curves were calculated from the least squares estimate of the random walk function. The relationship of the cardiac output, mean arterial pressure, and total peripheral resistance to the mean and the standard deviation were compared in a multiple stepwise linear regression. For each dog there was a definite linear relationship between total peripheral resistance and standard deviation (p less than 0.01). These results indicate that the dispersion of particles passing through the central circulation is directly related to the total peripheral resistance.

Animals↗
PubMed1977

Prolonged muscle rigidity following administration of succinylcholine.

Succinylcholine should be avoided in any patient with known myotonia because of the possibility of an abnormal rigid response. In addition, the possibility of undiagnosed myotonia should be considered in any myopathic patient. While not all myotonic responses are associated with malignant hyperthermia, the anesthetic should be discontinued immediately and the patient should be closely observed for elevation of temperature.

Child↗
PubMed1977

Recent developments in the clinical assessment of the metabolism of aromatics by high-performance, reversed-phase chromatography with amperometric detection.

High-performance liquid chromatography with electrochemical detection has developed into a tool with excellent capability to monitor picomole amounts of individual metabolites in both tissue and body-fluid specimens. Significant technical advances in the area of microparticle chemically-bonded stationary phases have led to dramatic improvements in both sensitivity and resolution. Reversed-phase systems can be modified to include charged exchange sites by addition of detergents to the mobile phase. Adjustment of the surface charge in this manner permits capacity factors for ionic sample components to be increased or decreased. This concept is quite compatible with electrochemical detection and has provided the foundation for several clinical assays now in routine use. Examples of additional applications are presented for the determination of catecholamines in tissue, 3-methoxy-4-hydroxyphenylglycol in urine, and dopamine-beta-hydroxylase activity in human serum.

Animals↗
PubMed1976

Effects of hyperbaric oxygen on behavioral and physiological measures in elderly demented patients.

This study tested the effects of repeated exposures to hyperbaric oxygen (HBO) on psychological, electroencephalographic, and cerebral blood flow measures in 8 patients with cerebrovascular disease and 13 patients with cortical atrophy. Patients were exposed to 100% oxygen at 2.5 atmospheres absolute twice daily for 90 min. for 15 days. No significant changes were observed in any of the measures in either group. Level of initial functioning was not associated with change due to treatment. Results suggest that HBO has no therapeutic effect in patients with moderate to severe dementia.

Aged↗
PubMed1976

The lagged normal family of probability density functions applied to indicator-dilution curves.

The generalized lagged normal functions are a family of probability density functions whose members consist of a normal density function convolved with one or more exponential functions. The functions are not expressible in closed form, but an error function approximation procedure allows rapid and accurate calculation of the value of these functions. The approximation procedure can be used in conjunction with a nonlinear regression program to fit a lagged normal function to experimental data.

Animals↗
PubMed1974

Genetic recombination in bacteriophage phi chi 174.

Genetic recombination in bacteriophage phiX174 usually takes place early in the infection process and involves two parental replicative form (double-stranded) DNA molecules. The host recA protein is required; none of the nine known phiX174 cistron products is essential. The products of a single recombination event are nonreciprocal and asymmetric. Typically, only one of the parental genotypes and one recombinant genotype are recovered from a single cell. An alternative, less efficient recombination mechanism which requires an active phiX174 cistron A protein is observed in the absence of the host recA gene product.

Alleles↗