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Biomedical subjects

L Nelson

Publications and source records attributed to L Nelson.

At least 145 records · Page 8Linked to original sources
PubMed1986

Effect of changing levels of physical activity on blood-pressure and haemodynamics in essential hypertension.

The long-term effect of exercise on blood-pressure (BP) was assessed in 13 untreated patients with essential hypertension. After a 6-week run-in period the levels of activity studied were sedentary, 45 min bicycling at 60-70% of maximum work capacity (Wmax) three times per week (3/week), and 45 min bicycling seven times per week (7/week), each for 4 weeks. The order differed between subjects in accordance with a Latin square. Supine BP, 48 h after each phase, averaged 148/99 mm Hg in the run-in and 143/96 mm Hg in the sedentary phase; it fell below values in the sedentary phase by 11/9 mm Hg with 3/week exercise, and by 16/11 mm Hg with 7/week exercise (both p less than 0.01). With increasing activity total peripheral resistance fell and the cardiac index rose. Plasma noradrenaline concentration fell below values in the sedentary phase by 21% and 33% after 3/week and 7/week exercise. Bodyweight and 24 h sodium excretion remained constant. Moderate regular exercise lowers BP and seems to be an important non-pharmacological method of treating hypertension.

Adult↗
PubMed1986

Late effects after treatment of twenty children with soft tissue sarcomas of the head and neck. Experience at a single institution with a review of the literature.

Twenty children with soft tissue sarcomas of the head and neck, treated at the Children's Hospital of Philadelphia and the Hospital of the University of Pennsylvania from 1972 to 1981, were evaluated for the late deleterious effects of treatment. All patients received radiation therapy and combination chemotherapy with vincristine, dactinomycin, and cyclophosphamide; certain patients also received Adriamycin (doxorubicin). All had ophthalmologic, otologic, growth, and cosmetic evaluations; 15 also had dental and maxillofacial examinations. The median age at diagnosis was 6 years (range, 7 months-13 years). Median follow-up from time of diagnosis was 5.5 years with a minimum of 3 years in all but four patients. The major problems encountered were related to the eyes (xerophthalmia and cataracts), ears (hearing loss), teeth (maleruption and caries), glandular structures (xerostomia, hypopituitarism), and development (craniofacial deformity). It is concluded that children treated for soft tissue sarcomas of the head and neck with combined modality therapy, including radiation enhancers, may show a variety of late treatment-related adversities. These children require close multidisciplinary follow-up for detection of late effects in order that appropriate prophylactic or symptomatic treatment can be instituted to minimize their consequences.

Adolescent↗
PubMed1986

A simple adjustable functional brace for tibial fractures.

The use of an adjustable functional brace for fractures of the tibia has several practical and theoretical advantages. The high cost of commercially available braces has limited their use until now. We describe a simple, inexpensive orthosis which has given good results in a clinical study for 32 unselected fractures. The fractures' alignment was well maintained. The brace was comfortable to wear and there were few complications. It is hoped that the low cost of this simple custom-made brace will encourage more widespread use of this technique.

Adolescent↗
PubMed1986

A comparison of the sensitivity of typing group-specific component (Gc) and the phosphoglucomutase (PGM1) locus in control and casework bloodstains by three isoelectric focusing methods.

The performance of typing group-specific component (Gc) in bloodstains by two isoelectric focusing methods followed by its detection with silver staining has been compared with an established forensic system of typing phosphoglucomutase (PGM1) locus phenotypes by isoelectric focusing (IEF) in 1 mm gels. For Gc typing ultra-thin isoelectric focusing (UTIEF) gels and immobilized pH gradient (IPG) gels were used. Both laboratory prepared stains and casework stains were examined. The Gc UTIEF method is approximately eight times more sensitive than the existing PGM1 1 mm IEF method for control and casework stains. However, on average, a larger amount of stain was taken from casework stains than control stains for each typing system. A total of 53 casework stains were examined. Comparable success rates of 62% and 64% were obtained for typing Gc on UTIEF gels and PGM1 by 1 mm IEF, respectively. A success rate of 55% was obtained for typing Gc on IPGs. Bloodstains that were over 200 days old were successfully grouped by all three methods.

Blood Stains↗
PubMed1986

Effects of meals on hemodynamics: implications for antihypertensive drug studies.

The ingestion of food is known to affect blood pressure and heart rate, but food is often allowed in patients under observation for antihypertensive drug effects. Seventy-seven patients with essential hypertension were observed for 8 hours after a 16-hour fast. Thirty-six continued to fast, 20 ate a high-carbohydrate meal, and 21 ate a meal of their own choice. Blood pressure and heart rate did not change during fasting, but both meals lowered mean supine and standing diastolic blood pressures during the subsequent 4 hours by 3 to 7 mm Hg (P less than 0.001). The high-carbohydrate meal reduced supine systolic blood pressure by 6 mm Hg (P less than 0.0001). Both meals increased supine and standing heart rates by 5 to 8 bpm (P less than 0.001). After the self-selected meal, standing systolic blood pressure increased in younger patients but decreased in older patients. Food ingestion during antihypertensive drug studies may interfere with the interpretation of results and should be avoided whenever possible.

Adult↗
PubMed1986

The effects of changes in physical activity on major cardiovascular risk factors, hemodynamics, sympathetic function, and glucose utilization in man: a controlled study of four levels of activity.

The effects of four levels of activity on heart rate, blood pressure, cardiac index, total peripheral resistance index (TPRI), norepinephrine (NE) spillover rate, insulin sensitivity, and levels of lipids and some hormones were studied in 12 normal subjects. The randomized periods were (1) 4 weeks of below-sedentary activity, (2) 4 weeks of sedentary activity, (3) 4 weeks of 40 min of bicycling three times per week, and (4) 4 weeks of similar bicycling seven times per week. Exercise three times per week reduced resting blood pressure by 10/7 mm Hg (p less than .01) and it was reduced by 12/7 mm Hg after exercise seven times per week (both p less than .01). This was associated with reduction in TPRI, an increase in cardiac index, and cardiac slowing. At the highest level of activity, NE spillover rate, an index of sympathetic activity, fell to 35% of the sedentary value (p less than .001) in eight of 10 subjects. In two other subjects NE spillover rate rose, although blood pressure and TPRI were reduced. Metabolic changes included lowering of total cholesterol, but high-density lipoprotein level was unchanged. Insulin sensitivity rose by 27% after exercise three times per week, but declined to sedentary levels with seven times per week exercise. Maximum oxygen uptake increased linearly with activity. Exercise performed three times per week lowers blood pressure and should reduce cardiovascular risk. The same exercise seven times per week enhances physical performance with little further reduction in cardiovascular risk factors. Exercise is potentially a major nonpharmacologic method of lowering blood pressure.

Adult↗
PubMed1986

Hepatic teratoma in an anencephalic fetus.

We report a case of hepatic teratoma that occurred in a 21-week-old fetus with anencephaly. This mature teratoma showed tissue derived from all three germ cell layers. To our knowledge, hepatic teratoma associated with anencephaly has not been reported previously.

Anencephaly↗
PubMed1985

Alterations in mitochondrial aconitase activity and respiration, and in concentration of citrate in some organs of mice with experimental or genetic diabetes.

Mouse islets (not used for respiration), kidneys and liver were studied in early and manifest alloxan diabetes, and in genetic diabetes. In these organs the mitochondrial aconitase activity was lower, state 3 respiration with citrate or pyruvate plus malate (but not with succinate) was decreased, and the concentration of citrate was increased, compared with non-diabetic control mice. The alterations suggest a role of lowered activity of mitochondrial aconitase in alloxan diabetes, and probably also in genetic diabetes.

Aconitate Hydratase↗
PubMed1985

Laboratory evaluation of the Coulter "three-part electronic differential".

Comparisons were made between "electronic" white blood cell (WBC) differential counts based on nuclear volume, differential counts performed by an automated image analyzer, and conventional manual counts performed by experienced technologists in a routine laboratory setting. The correlation between methods was excellent for lymphocytes (r = 0.9) and granulocytes (r = 0.9), but none of the three methods that were tested produced good results in enumeration of mononuclear cells (r = 0.6). Approximately 85% of the samples on which differentials were requested for an inpatient population could be processed by the electronic counter. Although the electronic counter failed to flag all abnormal samples (there were 6% false negatives), the performance of technologists doing 200 cell differentials was similar. Rapidly generated "electronic differentials" might be a useful and cost-effective adjunct to inpatient hospital practice if certain suggestions were implemented.

Adult↗
PubMed1985

A clinical trial of three-part electronic differential white blood cell counts.

Three-part white blood cell differential counts (diffs), performed during electrical impedance counting of blood cells, can accurately classify lymphocytes, granulocytes, and mononuclear cells in 85% of specimens, with an error rate not exceeding that of conventional diffs. To assess the clinical utility of the new test, we tried it for three months on a medical unit. Conventional diffs were no better than three-part diffs or total white blood cell counts in signaling clinical changes, and the same decisions would have been made in 78% of instances if only three-part diffs were available. The three-part diff is as reliable a clinical index for monitoring most inpatients as the conventional diff or white blood cell count. Although its use could effect significant cost savings, acceptance of the new test seems unlikely unless enforced by administrative flat.

Clinical Trials as Topic↗
PubMed1984

Enalapril for severe congestive heart failure. A double-blind study.

The effects of the new, orally administered converting-enzyme inhibitor, enalapril (MK-421), were studied in 12 ambulatory patients with severe cardiac failure who were also receiving digoxin and diuretic agents. The study was double-blind, parallel, placebo-controlled and randomized. The clinical characteristics and pretreatment exercise performance were similar in the two groups of patients. All vasodilator drugs had been withdrawn two weeks before the start of the trial. At 12 weeks, the patients receiving enalapril showed a significant improvement in the functional class of the disease, exercise time (P less than 0.01), and maximum workload achieved, and experienced relief of symptoms. Blood pressure fell in patients receiving active treatment suggesting a reduction of afterload. Left ventricular ejection fraction was unchanged in enalapril-treated patients, but fell in patients on placebo (P less than 0.001). Enalapril was well tolerated without apparent adverse effects. It was effective when used with digoxin and diuretic agents in the treatment of severe cardiac failure, and its efficacy was maintained throughout 12 weeks of therapy.

Administration, Oral↗
PubMed1984

Effects of changes in physical activity on blood pressure and sympathetic tone.

We investigated the relationship between the level of physical activity and blood pressure (BP). Twelve sedentary normotensive subjects were studied after consecutive one-month periods at four different levels of daily activity. These were minimal activity; usual sedentary activities; exercise three times weekly for 45 min at 60-70% maximum capacity (Wmax) on a bicycle ergometer and similar exercise performed daily. The order of the various levels of physical activity were randomised according to a Latin square. As expected there was a progressive increase in Wmax, maximum oxygen consumption and fall in resting and exercise heart rate with increasing activity. Supine blood pressure averaged 133/69 mmHg at the end of the sedentary period and fell by 10/8 mmHg after one month of exercise three times weekly and 12/8 mmHg after daily exercise (both P less than 0.001). The fall in resting BP with increased activity was due to lowering of total peripheral resistance. These haemodynamic changes were associated with biochemical evidence of marked reduction in overall sympathetic tone in 10/12 subjects especially after the period of daily exercise. Increased physical activity for one month lowers blood pressure in normotensive subjects. The fall with daily exercise is similar to that after some centrally-acting antihypertensive drugs, and may be due to a reduction in sympathetic nervous activity.

Blood Pressure↗
PubMed1984

Serum concentration of penicillin in the horse after repeated intramuscular injections of procaine penicillin G alone or in combination with benzathine penicillin and/or phenylbutazone.

Twenty-one adult horses were randomly assigned into 7 groups of 3 and were treated for 5 days with procaine penicillin G, benzathine penicillin , or phenylbutazone in various combinations and dosage schedules. Serum concentration of penicillin was measured serially over a 7-day period. The highest mean peak serum concentration was 2.06 micrograms/ml. Comparable peak values were seen 2 to 4 hours after administration of 22,000 IU of procaine penicillin G/kg of body weight given once or twice daily. A minimum serum concentration of 0.25 micrograms/ml was selected as adequate for efficacy against organisms that can be considered sensitive to penicillin. Once daily administration of procaine penicillin G and, although peak concentrations were lower, some regimens of procaine and benzathine penicillin G did maintain this concentration. Concurrent phenylbutazone administration did not affect serum concentration of penicillin appreciably.

Animals↗
PubMed1983

Ethanol intake increases during continuous administration of amphetamine and nicotine, but not several other drugs.

Groups of rats, acclimated to drinking both water and 10% v/v ethanol were implanted with a variety of slow-release devices containing d-amphetamine (d-amp), nicotine, caffeine, phencyclidine (PCP), secobarbital, LSD, mescaline or haloperidol. Ethanol intake was elevated only during treatment with d-amp or nicotine; none of the other drugs affected ethanol consumption even though the amounts of all drugs released were pharmacologically sufficient to affect behavior. Nicotine treated rats were not simply seeking calories provided by the EtOH solution, since nicotine treatment did not enhance intake of a distinctively flavored solution isocaloric to 10% ethanol. These results support a self-medication model of ethanol intake.

Alcohol Drinking↗
PubMed1983

Soft-tissue sarcomas of the head and neck in children.

Thirty-two children aged three months to 17 years (median six years) were diagnosed with soft-tissue sarcoma of the head and neck and treated at the Children's Hospital of Philadelphia and the Hospital of the University of Pennsylvania from 1971 to 1981. Thirty-one received chemotherapy and all received radiation therapy (RT). Twenty-five patients had pre-treatment computed tomography (CT) scans, which were used for staging and treatment planning. Doses of radiation therapy ranged from 3000 to 7300 rad to the primary tumor (median 5000 rad). The overall five-year survival of the entire group of 32 patients was 75%. Ten of the 32 patients had invasive cranial parameningeal disease as demonstrated by bony erosion at the skull base, seen on CT in eight and plain radiographs in two patients. Eight of these 10 patients have developed recurrent sarcoma: four in the meninges, two locally, one regionally and one distantly. Five of these 10 children with invasive cranial parameningeal sarcoma received 3000 rad of prophylactic cranial irradiation, begun within the first 12 days of chemotherapy, and none developed meningeal disease. In contrast, only one of the 22 patients without invasive cranial parameningeal disease has relapsed (local recurrence). The data suggest that soft-tissue sarcomas of the head and neck in children without invasion into the base of the skull (invasive cranial parameningeal disease) are usually cured. CT scans are essential for staging. Patients with invasion of the base of the skull may be protected from meningeal relapse by early cranial irradiation, although they still are at high risk for relapse in other sites.

Adolescent↗
PubMed1983

The role of prostaglandins in gentamicin-induced nephrotoxicity in the dog.

The effects of chronic gentamicin administration on renal function was studied in dogs receiving 4 mg/kg i.m. of gentamicin b.i.d. for 28 days. Administration of gentamicin resulted in a bimodal change in renal function. A decrease in urine osmolality was first noted on day 6 and declined progressively throughout the study. This decrease in urinary concentrating ability was preceded by a steady rise in urinary prostaglandin E2 (PGE) excretion and followed by a rise in plasma renin activity (PRA). Prior to an increase in azotemia, urinary PGE decreased precipitously while PRA continued to rise throughout the remainder of the study. The precipitous decrease in GFR was accompanied by a significant increase in FENa to seven times control. These studies suggest a dual effect of chronic gentamicin administration on renal function: (1) an early effect manifested by stimulation of urinary prostaglandin production with a concomitant loss of urinary concentrating ability and mild prerenal azotemia, and (2) a late effect, preceded by a decrease in urinary prostaglandin excretion while PRA continues to increase, and manifested by increase fractional excretion of sodium and progressive azotemia.

Acute Kidney Injury↗
PubMed1983

Uptake of labeled alloxan in mouse organs and mitochondria in vivo and in vitro.

[14C]2-Alloxan was administered in vivo and in vitro for study of the uptake of alloxan in different organs and their mitochondia of mice. After in vivo administration, radioactivity was demonstrated in all organs investigated, with quantitative differences: endocrine pancreas greater than liver greater than exocrine pancreas and heart. No significant difference was found between the iv and ip routes of injection. An in vivo uptake of alloxan was also found in mitochondria, with significant quantitative differences as to the origin of the organelles: endocrine pancreas greater than liver greater than exocrine pancreas and heart. Pretreatment with D-glucose caused significantly decreased uptake in liver, exocrine pancreas, and heart, but significantly increased uptake in endocrine pancreas, whereas the uptake was significantly decreased in the mitochondria from all of these organs. In vitro uptake was observed in all kinds of mitochondria studied. This uptake was higher than the in vivo uptake in mitochondria from liver, exocrine pancreas, and heart, whereas the uptake in vivo was higher than the in vitro uptake in islet mitochondria. The presence of D-glucose did not affect the in vitro uptake of alloxan in mitochondria. The findings show that in vivo, alloxan passes across plasma membranes and is taken up by mitochondria, and data obtained with mitochondrial subfractions may also indicate a passage across mitochondrial membranes. D-Glucose protection against alloxan diabetogenicity may be associated with prevention of mitochondrial uptake of alloxan. This prevention seems to be dependent on the metabolism of glucose.

Alloxan↗