Search PubMed⌕ Search

Biomedical subjects

J L Davis

Publications and source records attributed to J L Davis.

At least 199 records · Page 11Linked to original sources
PubMed1978

Pseudocaloric nystagmus.

Pseudocaloric nystagmus (PCN) is an appropriately beating nystagmus induced by cold caloric irrigation of an ear with abolished vestibular function. The nystagmus is not the result of endolymph flow but probably represents unmasking a latent nystagmus by altering the patient in this case, through tactile (caloric) stimulation. Pseudocaloric nystagmus has the following characteristics: (1) mild intensity (eyes closed-slow phase velocity usually less than 8 degrees/sec), it has not been observed with the eyes open, (2) always beats away from the diseased ear; therefore, any nystagmus induced by cold irrigation will be appropriately (contralateral) beating while that induced by warm irrigation will be inappropriately (contralateral beating; 3) the induced nystagmus will not reverse direction after inverting the ampulla. Establishing bidirectional sensitivity of the cupula by demonstrating appropriately beating nystagmus to ampullopetal and ampullofugal flow of endolymph not only assures that the lateral semicircular canal (SCC) is functionally intact to caloric stimulation but will avoid errors in electronystagmorgraphic (ENG) interpretation.

Caloric Tests↗
PubMed1978

D-Proline: stereospecificity and sodium chloride dependence of lethal convulsant activity in the chick.

Two- and five-day old chicks were injected intraventricularly with D-proline and structurally related compounds. D-proline produced convulsions and lethality, but was non-amnestic, whereas the naturally-occurring isomer, L-proline, was non-convulsant and non-toxic but amnestic. D-proline convulsions were accompanied by decreased high frequency in the EEG and increased slow wave activity. High amplitude spiking was not observed. The lethality of D-proline was saline-dependent. Control experiments ruled out possible toxic factors such as hypertonicity, pH pyrogens, injection volume, or needle misplacement. The results demonstrate that saline and distilled water are not equivalent injection vehicles. A sodium-free vehicle may lead to artifacts but is advantageous in experiments in which amino acid transport must be minimized.

Animals↗
PubMed1978

Template bleeding time and clinical hemorrhage in myeloproliferative disease.

In 32 patients with myeloproliferative disorders (MPD), correlations were made among clinical observations of hemorrhagic tendency, template Ivy bleeding time, and platelet aggregation studies. Bleeding time was commonly prolonged, particularly in myelofibrosis. In two cases, this prolongation appeared to reflect a defect in platelet function, which resulted in clinical bleeding. Prolongation of bleeding time did not correlate with degree of thrombocytosis. Two patients with thrombocytosis had serious clinical bleeding at a time when bleeding time was normal. Of the patients, 35% had abnormal findings from aggregation studies, but there was no correlation between aggregation studies and prolongation of bleeding time or clinical hemorrhage. We conclude that bleeding in MPD arises either from a defect in platelet function, which is reflected in a prolonged bleeding time, or from thrombocytosis.

Blood Cell Count↗
PubMed1977

Peripheral diabetic neuropathy treated with amitriptyline and fluphenazine.

The pain of diabetic peripheral neuropathy responds poorly to current modes of treatment. We treated eight patients with this disorder whose pain was refractory to standard regimens but who experienced remarkable pain relief within two to five days after treatment with fluphenazine hydrochloride, amitriptyline hydrochloride, or a combination of the two. In four patients whose regimens were discontinued, pain recurred within two days and again remitted on reinstitution of the drug regimens. These findings suggest that fluphenazine alone or in combination with amitriptyline may be of benefit in treating the painful peripheral neuropathy associated with diabetes.

Adult↗
PubMed1977

A parent advice package for family shopping trips: development and evaluation.

THIS ARTICLE REPORTS ON THE PRIMARY STEPS IN THE DEVELOPMENT OF PARENT ADVICE FOR POPULAR DISSEMINATION: (a) developing advice for one specific problem situation, family shopping trips; (b) testing the advice program for benefit to children and convenience to adults; and (c) packaging the advice so it can be used successfully by interested parents. Systematic observation of 12 families using the written advice package on shopping trips revealed its effectiveness in reducing child disruptions and increasing positive interactions between parents and children. These findings, along with interview information from families, showed that the package is usable, effective, and popular with both parents and children, and thus is ready for dissemination to a wide audience of parents-a step that in itself should involve research and evaluation.

Journal Article↗
PubMed1976

The affinity of rat liver ribosome subunits for degranulated rough microsomal membranes.

Potassium and magnesium ion concentrations affected the extent but not the specificity of binding in vitro of 60-S and 40-S ribosome subunits to degranulated rough microsomal membranes from rat liver. Scatchard plots revealed that under ionic conditions most likely to resemble those in vivo, the affinity constants for binding 60-S subunits were approximately four-times greater than those characterizing 40-S subunit binding. Further, the extent to which subunits bound at saturation was close to the level of ribosomes present in intact membranes.

Animals↗
PubMed1976

The development of passive and active avoidance learning in the cat.

Kittens of 25 and 50 days of age were tested on a passive avoidance task in a 2-compartment black-white shuttle box. Latency to enter the dark side of the box was the same for both groups on Day 1, but the latency to enter the dark side on Day 2 was much shorter for the younger kittens. Other kittens were trained in a step-up active avoidance task also at 25 and 50 days of age. No differences were found in active avoidance performance between the younger and older animals, indicating that active and passive avoidance tasks may possibly reflect separate developmental processes that mature at different rates in the cat.

Age Factors↗
PubMed1976

Evidence for an intrarenal beta receptor in control of renin release.

Infusion of isoproterenol intravenously in normal dogs at rates of 0.10 or 0.018 mug/min per kg body wt increased renin secretion; at the lower infusion rate arterial pressure (AP) and renal blood flow (RBF) were unchanged. Isoproterenol was also infused into the renal artery in normal dogs at 0.10 mug/min per kg; renin secretion increased in association with an increase in RBF but AP was unchanged. Plasma K concentration was consistently decreased in all three of the above experiments and because hypokalemia is known to increase renin release isoproterenol was not infused intrarenally at the lower rate; the decrease in plasma K level precluded relating the entire response in renin release to isoproterenol. Intrarenal infusion of propranolol at 0.05 mg/kg per h in Na-depleted dogs decreased renin secretion whereas intravenous infusion at the same dose failed to alter renin release. Intrarenal infusion of propranolol at this rate in Na-depleted dogs with a denervated, nonfiltering kidney also decreased renin release. In contrast, intrarenal infusion of phentolamine or phenoxybenzamine in normal dogs failed to alter renin secretion in doses that blocked alpha-adrenergic receptors. These experiments provide strong evidence for an intrarenal beta-adrenergic receptor that mediates renin release, and it seems likely from the experiment in the denervated, nonfiltering kidney that the receptor is located in the juxtaglomerular cells.

Animals↗
PubMed1975

Unit activity in posterior association cortex of cat.

1. "Association" neurons in the posterior middle suprasylvian gyrus of cat were found to be predominantly polysensory, with 82% of the units in the chloralose-anesthetized preparation responding to auditory, visual, and somatic stimuli. There was no evidence of response differentiation associated with cortical depth distribution. Most units responded with a short-latency response (median 35-60 ms) to all stimulus modalities, with the response to visual stimulation occurring at the shortest latency. Among polysensory cells, almost half responded with equal probability to auditory, visual, and somatic stimulation. The visual stimulus was the most potent for those cells responding with a higher probability to a single modality. Varying degrees of response complexity were noted in some cells in terms of changes in responsivity over time, discharge to stimulus offset, and inhibition of spontaneous activity. The unitary discharge was seen to occur on the negative peak and slope of the locally recorded evoked potential. When only the larger amplitude spikes were analyzed, most of the unitary activity occurred on the negative peak of the evoked potential. Almost half of trimodally responsive cells displayed similar phase relationships between unitary activity and evoked potentials for all three modalities. The absolute refractory period for most cells was from 200 to 300 ms, with relative refractory periods extending up to 30 s...

Anesthesia, General↗