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Biomedical subjects

P Harris

Publications and source records attributed to P Harris.

At least 271 records · Page 15Linked to original sources
PubMed1983

Evolution and the cardiac patient.

These essays have traced the evolution of three great convective systems of the body: ventilation, circulation and excretion. We have seen how the ventilatory system evolved with an inherent susceptibility to flooding, how the kidney came to need an enormous blood flow and how a high blood pressure grew out of the explosive demands of muscular activity. Success and survival in the animal kingdom have overwhelmingly depended on physical mobility and strength. To ensure this the body makes use of the neuro-endocrine defence reaction which is also life-saving in injury. The reaction favours the retention of water and salt by directing blood away from the kidney and by endocrine activity. When the output of the diseased heart decreases, the body reacts in the way for which nature has programmed it. It cannot distinguish. But now the neuro-endocrine response persists. But now the neuro-endocrine response persists. Over weeks or months or years the retention of saline threatens the cardiac patient with drowning in his own juice. And every hour of the day and night be is running for his life.

Adrenal Cortex Hormones↗
PubMed1983

Low risk of late post-traumatic seizures following severe head injury: implications for clinical trials of prophylaxis.

A randomised, controlled, double-blind clinical trial designed to determine the effectiveness of phenytoin in preventing epilepsy in patients who had suffered a serious head injury is reported. One hundred and sixty-four patients were randomly assigned to treatment with phenytoin or placebo capsules for one year. Patients who had a fit within one week of injury were excluded. Drug levels were monitored throughout with appropriate dosage adjustment; however only 48% of the phenytoin group had plasma levels greater than 40 mumol/l. There were seven deaths during the study. Only 11 patients (six in the phenytoin group and five in the placebo group) developed post-traumatic epilepsy within one year; a further four patients developed seizures between 1 and 2 years after injury. This low incidence of post-traumatic epilepsy (7% (SE 2%) at one year and 10 (SE 2%) at two years) means that future clinical trials of prophylaxis will have to be much larger (at least six fold).

Adolescent↗
PubMed1983

Ontogeny of hepatic insulin and glucagon receptors and adenylate cyclase in rabbit.

In rabbit liver plasma membranes (LPM), specific binding of 125I-insulin rapidly increased in late gestation and peaked at birth, declining thereafter. In contrast, 125I-glucagon binding was lowest in late gestation, somewhat higher at birth, and increased by 48 h although only to 20-25% of adult. These changes in binding were due to changing numbers of receptors involving predominantly high affinity sites for insulin and low affinity sites for glucagon, with only minor changes in affinity. Despite measurable glucagon receptors by birth, fetal LPM produced no increment above basal in cAMP production with maximal doses of glucagon (10(-6) M), prostaglandin E1 (10(-4) M), or epinephrine (10(-4) M). Near birth only NaF (10 mM) produced a modest but significant increment in cAMP. By 2 h postbirth, all stimuli evoked significant increments in cAMP production that increased progressively but was still only 15-20% of adult at 48 h. Furthermore, although specific binding of cholera toxin was greater in fetal LPM (11 +/- 1 vs. 6 +/- 1%), cholera toxin-stimulated cAMP production increased by only 12-26% above basal in the fetus compared with 220% in adult. Markers of membrane purity including 5'-nucleotidase, phosphodiesterase, and insulin or glucagon degradation were not different in fetus and adult. We conclude that receptors and components of the adenylate cyclase complex mature independently; initial coupling occurs between the G/F regulatory protein and the catalytic unit (NaF but not hormonal activation) followed within hours of birth by coupling to the hormone receptor.

Adenylyl Cyclases↗
PubMed1983

The Hancock external valved conduit. A dichotomy between late clinical results and late cardiac catheterization findings.

The Hancock external valved conduit was inserted in 18 children between 1974 and 1977. Seventeen patients survived operation and 15 are long-term survivors of 6 to 9 years. All patients have been closely followed up by the same pediatric cardiologist and each has undergone serial cardiac catheterization studies, generally performed at 1 and 6 years after operation. All long-term surviving patients have been in either New York Heart Association Class I or II. A few continue to take digoxin or diuretics. Cardiac catheterization demonstrated a gradient of 50 mm Hg or greater across the conduit in two of 16 patients 1 year after operation and in seven of 15 patients 6 years after operation. Five patients (30% of all long-term survivors) have had this conduit replaced and each has survived reoperation. The finding of a severe conduit gradient in one third of all long-term surviving patients is particularly bothersome since these patients were essentially asymptomatic. This study emphasizes the need for serial follow-up cardiac catheterization studies in all patients who receive the Hancock conduit.

Adolescent↗
PubMed1982

Newborn thyroid screening in a municipal hospital.

Successful recall of patients with abnormal results of neonatal screening tests is difficult to accomplish. A system of centralization of the process was implemented at a municipal hospital and evaluated after one year. Two thousand two hundred thirty-four newborn infants were screened for congenital hypothyroidism. Ninety-one percent of the 101 infants who required recall were returned for retesting. Centralization of the process of recall of newborns with abnormal screen results was an effective way to obtain additional specimens successfully in a setting in which patients use carried pediatric primary health care facilities. However, the high recall rate experienced by our hospital resulted in high costs in terms of professional and personnel time and anxiety for the individual families.

Congenital Hypothyroidism↗
PubMed1982

Residual effects of repeated doses of 0.5 and 1 mg flunitrazepam.

9 normal subjects were tested on a large battery of tests the morning after a hypnotic dose of flunitrazepam (0.5 mg and 1 mg) and a placebo. Each drug was given for 8 nights and assessments were made 10 and 13 h later on days 1, 4 and 8. Self-ratings of sleep were made every morning. The tests comprised mood and bodily symptom self-ratings, taping rate, visual reaction time, symbol copying and substitution tests, critical flicker fusion threshold, digit span and cancellation test. The EEG was recorded under eyes open and eyes closed conditions and analysed using broad waveband filters. Subjectively, the 0.5 mg dose was associated with increased alertness, contentment and calmness, the 1 mg dose with minimal decrease in alertness and contentment. Sleep onset was accelerated by flunitrazepam initially but effects on quality of sleep were not major due to subject selection. The 1 mg dose occasionally impaired performance on tapping, symbol copying and substitution and critical flicker fusion. The 0.5 mg dose marginally impaired symbol substitution and improved symbol copying. The EEG showed definite dose-related effects which tended to increase over the 8 nights of ingestion of the drug. It is concluded that whereas the 1 mg dose may sometimes be associated with definite residual effects the next day, the 0.5 mg dose possesses positive qualities in producing useful subjective effects the next day without appreciable impairment of psychological performance.

Adult↗
PubMed1982

The effect of Routine nursing care procedures on the ICP in severe head injuries.

The intracranial pressure (ICP) was monitored in a number of patients who were being treated by mechanical ventilation for head injury. The effect on the pressure of routine nursing procedures was studied. Fourteen out of thirty-three cases (group 1) showed small reversible rises in ICP during suction, insertion of a N/G tube, or i.m. injections. These were associated with similar small increases in intrathoracic pressure and small fluctuations in arterial blood pressure. These rises were effectively treated with additional doses of relaxants. In a small group of patients (group 2) irreversible intracranial hypertension was induced by some of these stimuli, but did not respond to the administration of more relaxants, although sedatives such as papaveretum reduced it in some cases, but only slightly.

Adolescent↗
PubMed1982

Pulmonary circulation of the llama at high and low altitudes.

We have studied the pulmonary circulation of three closely related animals, the llama, alpaca, and guanaco. The mean pulmonary arterial pressure of 12 llamas and one alpaca indigenous to high altitude in the Andes was found to be slightly but significantly higher than that of three llamas and three guanacos born and bred at low altitude in England. On the other hand, the medial thickness of the muscular pulmonary arteries and the relative weights of the two ventricles were the same in three llamas and one alpaca at high altitude as they were in one llama and two guanacos at low altitude. It is concluded that the pulmonary vasoconstrictive response to hypoxia, while present, is greatly reduced in this species and it is suggested that this may have taken place by evolutionary adaptation.

Altitude↗
PubMed1982

Echo perception of shape and texture by sighted subjects.

Experienced blind subjects have previously demonstrated good echo perception of size and distance and some echo-discrimination of shapes and textures. In three experiments untrained sighted subjects also proved able to echo-detect and recognize three simple shapes and to recognize fabric and wooden but not carpet and Plexiglas discs at significantly above chance levels. Some improvement occurred over the first few trials but little thereafter, suggesting that this sort of echo perception requires very little training. A blind subject exhibited over-all accuracy comparable to those of sighted subjects. There were, however, interesting differences between the blind subject and the sighted subjects in echo perception of specific stimuli and in approach to the task.

Adolescent↗