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Biomedical subjects

M Maxwell

Publications and source records attributed to M Maxwell.

At least 73 records · Page 4Linked to original sources

Comparison of hot contrast material and hot saline for renal ablation in a canine model.

Renal ablation was performed in eight dogs with either 76% diatrizoate for normal saline. Both fluids were heated to 100 degrees C before injection. Coagulation necrosis and tubular atrophy were seen with both agents, indicating that much of the effectiveness of hot contrast material is due to heat. Diatrizoate also caused glomerular sclerosis, probably due to its inherent nephrotoxicity. Hot diatrizoate is probably more effective for renal ablation, but may not have an advantage over hot normal saline outside the kidney. Because of the risk of infection, prophylactic antibiotics are advised when renal ablation is performed with hot fluids.

Animals↗

Defective renal prostaglandin synthesis in hypertensive patients with morbid obesity.

Renal prostaglandin synthesis in 36 obese hypertensive patients was estimated from measurements of 24-hour urinary prostaglandin E2 (PGE2) excretion rates. PGE2 was measured by radioimmunoassay using Dray antiserum prior to and 1 week after starting a fast supplemented by 320 cal derived from 30 g of carbohydrate, 45 g protein, and 2 g essential fatty acids. Sodium intake was 120 mEq daily or less. Comparisons were made to a control population of age-matched, nonobese, normotensive, healthy volunteers on a normal diet. Mean weight fell from 260 +/- 8 to 247 +/- 8lb, p less than 0.001. Urinary PGE2 in the obese patients prior to the fast was 104 +/- 27 ng/day, significantly lower than the 404 +/- 124 ng/day found in the control population, p less than 0.005. After the 1st week of the fast urinary PGE2 rose to 213 +/- 55, p less than 0,02. This value was not different from that in the control group. Blood pressure fell (p less than 0.001) in these patients from 143/94 +/- 3/2 to 134/87 +/- 3/2 mm Hg after the 1st week of the fast. Deficient renal prostaglandin synthesis in obese hypertensive patients was corrected by fasting. Such changes in the prostaglandin system may mediate or occur in response to changes in the sodium-volume balance of these patients. These changes in renal prostaglandin synthesis may partly contribute to the blood pressure reduction of these patients.

Blood Pressure↗

Life begins here.

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Adolescent↗

The brain.

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Brain↗

The kidney.

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Glomerular Filtration Rate↗

The liver.

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Gallbladder↗

A comprehensive psychological approach to obesity.

Many different treatments for obesity have proven somewhat successful, with none emerging as clearly superior to the others. Surgical approaches, although usually successful at achieving and maintaining weight loss, are accompanied by varied and often harmful side effects. Unless new, safer procedures are developed, treatment may continue to be as hazardous as the obesity itself. Because medical treatment alone has not achieved beneficial, lasting results, research aimed at finding new procedures should be encouraged. Our five-year experience in working with obese patients has led us to the following conclusions: 1. The management of obesity must be a joint venture between psychiatry and medicine. Because of the complex nature of this illness, neither discipline alone can successfully and safely achieve significant initial weight loss coupled with successful long-term maintenance. The use of adjunctive psychological programs in a medical setting can be a successful alternative. 2. Fasting, weight loss, and realimentation must be accompanied by an effort at lifestyle change. Otherwise, patients will continue their self-destructive habits, which will ultimately lead to failure in yet another attempt at sustained weight reduction. The behavioral approach has provided a fairly effective treatment of obesity, sometimes with immediate results. Recent studies support the maintenance effect of behavioral treatments. However, longer studies with follow-ups are needed to better assess the overall effectiveness of these treatments. 3. Despite much false optimism that weight loss is a simple road to happiness, most patients experience some very real problems during the fasting part of the program. Crisis intervention can prove very helpful in terms of reducing stress and preventing dropouts. Group therapy, individual therapy, family therapy, and hypnosis have attained some very limited positive results when used alone; greater success has been reported from combining therapies. Patients generally became more socially effective, physically active, and mentally proficient when exposed to individual therapy together with group and family therapies. 4. Family environment appears to significantly affect compliance and completion. A conflict-laden family environment hampers the patient's ability to deal with the psychological changes encountered in weight loss programs. 5. Many obese patients lack a fundamental knowledge of nutrition, exercise, and health. In addition, most are poorly socialized and require assistance in learning assertiveness and other interpersonal skills. A behaviorally oriented component is very effective in providing these skills.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

Pindolol: effects on blood pressure and plasma renin activity.

The influence of pindolol, other antihypertensive agents, or placebo upon plasma renin activity (PRA) was examined in five separate studies involving 249 subjects (pindolol), n = 149; propranolol, n = 43; methyldopa, n = 13; chlorthalidone, n = 16; placebo, n = 28). In addition, the subjects were stratified in for studies into low (n = 104), medium (n = 96), or high (n = 15) PRA categories according to baseline PRA and sodium excretion measurements. The response to antihypertensive therapy was analyzed in each PRA category. Pindolol and propranolol lowered PRA comparably at equivalent dosages, although this effect was not consistently observed in all studies or at all dosage levels. Methyldopa therapy was not associated with a decline in PRA and chlorthalidone elevated PRA. Pindolol and propranolol lowered both supine and erect diastolic blood pressure (BP) comparably. This effect was similar in subjects categorized as having low or medium PRA. Too few patients were studied with high PRA to derive statistically meaningful data. Pindolol lowered standing systolic BP to a greater extent than did propranolol, especially in the medium PRA category. It was concluded that pindolol, like other beta-adrenergic blockers, lowers PRA, that the effect of pindolol on diastolic BP is independent of the baseline PRA category, and that pindolol is more effective than propranolol in lowering standing systolic BP, at least in the medium PRA category.

Adult↗

Role of the sympathetic nervous system in blood pressure maintenance in obesity.

A group of 10 borderline hypertensive obese subjects had higher (P less than 0.05) supine plasma norepinephrine (NE), epinephrine, and PRA levels as well as greater (P less than 0.05) NE responses to upright posture and isometric handgrip exercise than 12 nonobese controls. Plasma NE as well as mean arterial pressure (MAP) responses to posture and handgrip in the obese patients demonstrated a significant decrement at week 2 after the onset of a low calorie diet. Decrements in plasma NE and MAP responses to posture were correlated (r = 0.61; P less than 0.05) throughout an 8-week period of weight loss in these borderline hypertensive obese subjects. In 15 normotensive obese subjects as well as in the 10 borderline hypertensive obese subjects, weight reduction associated with a very low calorie intake was accompanied by a reduction in supine plasma NE, epinephrine, and MAP 2 weeks after the onset of dieting. PRA decreased after 8 weeks of dieting in both obese groups, and these PRA decrements were correlated with reductions in MAP and decrements in plasma NE. We conclude that enhanced sympathetic activity may play a role in the maintenance of elevated blood pressure in obese individuals. Decreases in PRA and blood pressure associated with weight loss in both normotensive and hypertensive obese individuals occurs, in part, secondary to reductions in plasma NE levels.

Adult↗