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Biomedical subjects

J Young

Publications and source records attributed to J Young.

At least 487 records · Page 27Linked to original sources
PubMed1980

Reversal of paradoxical sleep deprivation by amygdaloid stimulation during learning.

Rats were subjected to a partial, selective paradoxical sleep (PS) deprivation. Two groups were trained in a shuttle avoidance task, one receiving posttraining amygdaloid stimulations (AS). A third group received AS, but was not trained. Levels of PS in the AS trained group were higher than in the AS non-trained controls, while the reverse was true for the slow wave sleep (SWS) measure. Both AS groups had levels of PS and SWS superior to the non-AS trained rats. In a second experiment, a group of normally rested AS animals was trained in the same task with a non-AS control group. These groups did not differ in terms of learning performance. Results were believed to support the hypothesis of a close relationship between sleep and learning.

Amygdala↗
PubMed1980

Computerised tomographic (CT) abdominal scanning in Hodgkin's disease.

Thirty-nine patients with Hodgkin's disease (HD) with little or no clinical evidence of abdominal disease were investigated by abdominal CT scanning. The results were compared with those of bipedal lymphography and laparotomy and splenectomy. In the assessment of para-aortic lymph nodes, CT scanning and lymphography were of equal efficacy in determining the presence or absence of disease (87 and 79% respectively). Although CT scan could occasionally demonstrate disease in nodes in areas other than the retroperitoneum, its value was limited by its inability to detect involvement of nodes which were not significantly enlarged. CT assessment of splenic HD was unreliable, focal deposits being detected in only one of the 11 spleens involved. In this selected group of patients, CT scan had little advantage over lymphography in the description of disease extent. However, CT scan would appear to be the investigation of choice in patients with suspected abdominal relapse because of the more frequent presence of disease in sites not seen on lymphography. When treatment decisions are dependent on accurate knowledge of distribution of disease, CT scanning cannot yet effectively replace staging laparotomy and splenectomy as the means of achieving this information.

Hodgkin Disease↗
PubMed1980

The acute effect of angiotensin II on adrenal and anterior pituitary function in normal subjects and subjects with primary hyperaldosteronism.

Previous studies have shown that infused angiotensin II acutely suppresses ACTH release. In normal human subjects, the response to angiotensin II infused alone is specific to aldosterone and 18-hydroxycorticosterone. Other compounds such as cortisol, corticosterone and DOC do not respond. This is transformed into a general adrenocortical response by infusing small, constant quantities of ACTH. In patients with primary hyperaldosteronism, a poor response of plasma aldosterone to angiotensin II infused alone was altered to a response comparable with that in normal subjects by supplying ACTH during the infusion. Aldosterone secretion is more sensitive to ACTH in cases of primary hyperaldosteronism than in normal subjects. The poor response to angiotensin infusion may have been caused by inhibition of ACTH release, a phenomenon shown to occur in normal human subjects.

Adrenal Glands↗
PubMed1980

Prolonged increases in paradoxical sleep during and after avoidance-task acquisition.

Rats were trained in a two-way shock-avoidance task, either in a single training session of 100 trials or over a 5 day period with 20 trials per day. Electroencephalograph and electromyograph recordings were continuous for 2 days prior (base line), during, and following the experiments, except during the actual training sessions. Animals that learned the task showed marked increases in PS. Rats that learned the distributed trials training task showed PS increases in the 24 hr period prior to a maximum increase in correct performance. These PS elevations appeared after a 10 hr latency following the training session. The animals that learned the single training session exhibited PS increases that persisted for a period of 6 days, which appeared daily in a cyclic manner. The latency to onset of these PS changes was less than 1 hr. The PS increases in both types of training were due to an increase in the number of PS periods and are believed to be different manifestations of the same flexible mechanism. This mechanism is considered to be involved with some aspect of learning other than the acquisition process, such as retention.

Animals↗
PubMed1979

The effect of penicillin on the release of gamma-aminobutyric acid from cerebral cortex slices.

Penicillin is known to block the depressant action of GABA on cortical and spinal neurons. In this study we examined the effect of penicillin on the release of endogenous amino acids from rat cerebral cortex slices. The principal finding was that penicillin blocked the potassium-stimulated release of GABA, a calcium-dependent process. It did not block the veratridine-stimulated release of GABA, a calcium-independent process. It did not affect the release of other putative transmitter amino acids. Inhibition of GABA release from nerve endings may explain in part the ability of penicillin to depress synaptic inhibitory mechanisms.

Amino Acids↗
PubMed1979

Bidirectional movement of gamma-aminobutyric acid in cerebral cortex slices incubated in small volumes of medium.

Rat cerebral cortex slices were incubated in small volumes of medium in order to study the bidirectional movements of gamma-aminobutyric acid (GABA) between tissue and medium, and to measure the extent of release of endogenous amino acids of interest as potential neurotransmitters. The apparent uptake, real uptake, and net change of GABA were calculated from the changes in [14C]GABA and endogenous GABA in the medium. The extent of release of endogenous amino acids was dependent upon the amino acid the duration of incubation, and the volume of incubating medium. Substantial amounts of endogenous amino acids may accumulate in the medium under conditions commonly employed in amino acid uptake studies. The accumulation of endogenous GABA may affect the calculation of GABA uptake when this is based on the initial specific activity of exogenous [14C]GABA. The difference between apparent uptake and real uptake was particularly prominent in the presence of the depolarizing agents, potassium or veratridine, which caused a marked increase in GABA release. Exchange or net release of GABA was found when slices were incubated briefly in media containing 1.3 micrometer or 12.5 micrometer exogenous GABA; net uptake accounted for 50% of observed uptake when slices were incubated in media containing 25 micrometer GABA.

Amino Acids↗
PubMed1979

Effect of barbiturates on release endogenous amino acids from rat cortex slices.

The potassium-stimulated, calcium-dependent release of endogenous GABA and glutamic acid was suppressed by pentobarbital. The ouabain and veratridine-stimulated fluxes of the amino acids, calcium-independent processes, were not suppressed by pentobarbital. Release of GABA and glutamic acid was not suppressed by pentobarbital in the presence of the calcium ionophore A23187. Of eight barbiturates studied at equimolar concentrations six were found to inhibit GABA release. Thiopental was the most potent, and phenobarbital and secobarbital were inactive.

Amino Acids↗
PubMed1979

The influence of preloading on stress relaxation of orthodontic elastic polymers.

The main objective of the investigation was the determination of whether prestretching would decrease the rapid force loss of the elastic polymers. The results indicated that Alastik CK chains showed a significant decrease in force loss whereas the C2 chains were unaffected. Since overextending the chain to compensate for force loss during clinical placement could result in capillary bed ischemia, increasing the force loss of the CK chains must be done before application. To accomplish this the chains should be prestretched by the manufacturer or operator. An improvement in the material component or manufacturing process would provide a more lasting solution to a material for which orthodontists have found increasing use.

Elasticity↗
PubMed1979

The handling of immunoreactive vasopressin by the isolated perfused rat kidney.

Using the isolated rat kidney perfused with an artificial medium containing glucose as the sole fuel, we studied the renal handling of immunoreactive arginine vasopressin (AVP) and determined the effect of various factors on the ability of the kidney to remove AVP. In control kidneys perfused with AVP at concentrations below 116 muU/ml, the organ clearance of AVP (OC(AVP)) was 1,145+/-47 (SE) mul/min, whereas glomerular filtration rate (GFR) averaged 515+/-37 mul/min. Filtration could thus account for up to 45% of the OC(AVP), the balance presumably being cleared from the peritubular circulation. Of the AVP filtered, only 38% could be recovered in the urine (urinary clearance AVP averaged 205+/-12 mul/min) suggesting that the balance was taken up by the tubular epithelium and degraded. Fractional excretion of filtered AVP rose significantly in the presence of anoxia and cold (10 degrees C) to 49 and 59%, respectively, but was not affected by ouabain or high levels of AVP (458+/-58 muU/ml). The OC(AVP) was not significantly altered by the absence of glucose in the perfusate, anoxia, or ureteral ligation, maneuvers that were associated with significant reductions in GFR. In these and the control experiments, there was a significant inverse correlation between GFR and peritubular clearance emphasizing the importance of the latter (r = -0.749; P < 0.001). Cold, ouabain, and high concentrations of AVP reduced the clearance of AVP by the kidneys. On the basis of these studies we conclude that the kidney clears AVP from the circulation via two pathways, glomerular clearance and peritubular clearance. This exposes both the luminal and contraluminal surfaces of the tubular cells to the hormone, allowing these cells to remove AVP from the filtrate and the peritubular compartment. Noteworthy is the observation that under several conditions when GFR falls reducing the glomerular clearance of AVP, peritubular clearance increases and the total clearance of AVP by the kidney remains constant.

Albumins↗
PubMed1979

Home parenteral nutrition in treatment of severe radiation enteritis.

Ten patients with radiation enteritis unresponsive to conventional medical and surgical therapy were put on long-term parenteral nutrition at home. Six of the patients are alive at home; four patients died, two from recurrent cancer. Some of the patients have been able to resume oral intake, but none have been able to discontinue parenteral nutrition. Fistulas healed or had a marked decrease in output. Two patients in our series were given prednisone and slinical improvement of radiation enteritis with this therapy.

Abdominal Neoplasms↗
PubMed1979

Are low-cholesterol diets expensive?

To serve as the basis of cost comparison, USDA "moderate-cost" and "thrifty" menus for one week were modified to meet guidelines for a cholesterol-lowering diet. Prices of individual items on the menus at both cost levels were obtained from two supermarkets and averaged. Items on the moderate-cost, cholesterol-lowering diet were $1.37 less than the USDA menus. At the low-cost level, the modified menus cost 22 cents more. In neither case was the difference significant by the t-test.

Adult↗