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Biomedical subjects

M Horowitz

Publications and source records attributed to M Horowitz.

At least 289 records · Page 16Linked to original sources
PubMed1994

Low-dose enzyme replacement therapy for Gaucher's disease: effects of age, sex, genotype, and clinical features on response to treatment.

Although alglucerase therapy has become the treatment of choice for symptomatic patients with Gaucher's disease, the low-dose/high-frequency regimen introduced as a means to reduce the high cost of treatment has raised major controversy. We evaluated the efficacy and safety of low-dose alglucerase in 29 patients with Gaucher's disease who completed 6 to 28 months of therapy. All received intravenous alglucerase at a monthly dose of 30 units/kg, given usually in equal doses 3 times a week. All patients responded well to treatment. The hematological improvement and the reduction in organomegaly were satisfactory. No correlation was found between age, sex, genotype, previous splenectomy, or severity score index and the response to treatment. Patients with a greater degree of hepatomegaly tended to have a more pronounced decrease in liver size, although this reduction did not reach statistical significance. We confirmed that a low-dose/high-frequency regimen of alglucerase was as effective as a high-dose/low-frequency protocol in the treatment of Gaucher's disease, even in the severely ill. Whenever cost is an issue, we recommend using this low-dose regimen.

Adolescent↗
PubMed1994

Effects of duodenal distention on fasting and postprandial antropyloroduodenal motility in humans.

BACKGROUND/AIMS: Mechanoreceptors in the proximal small intestine may play an important role in the regulation of gastric emptying. Balloon distention of the duodenum causes fundic relaxation. The purpose of the present study was to determine the effect of stimulation of duodenal mechanoreceptors on both fasting and postprandial antropyloroduodenal motility in humans. METHODS: Antropyloroduodenal pressures were recorded in 12 healthy volunteers with a sleeve-sidehole assembly, incorporating two balloons 5 and 20 cm distal to the pylorus. Duplicate proximal and distal duodenal balloon distensions with 10, 20, and 30 mL of air for 2.5 minutes were performed separately and in randomized order both during fasting and after a meal. RESULTS: During fasting, proximal and distal distention at all volumes increased the number of isolated pyloric pressure waves (P < 0.05) and basal pyloric pressure (P < 0.05), and the response to proximal distention was greater (P < 0.05). Postprandially, proximal and distal distention increased basal pyloric pressure (P < 0.05) with a greater response to proximal distention (P < 0.05), but had no effect on isolated pyloric pressure waves. Both during fasting and postprandially, there were more synchronous and less antegrade antral waves during distention (P < 0.05). The number of duodenal pressure waves increased during proximal (P < 0.05) but not distal distention. CONCLUSIONS: Stimulation of duodenal mechanoreceptors by balloon distention has significant and region-dependent effects on antropyloroduodenal motility that vary between fasting and postprandial states.

Adult↗
PubMed1994

Bolus i.v. nitroglycerin treatment of ischemic chest pain in the ED.

A prospective case series was conducted to demonstrate the safety and efficacy of intravenous nitroglycerin (i.v. NTG) boluses in the treatment of ischemic chest pain (CP) in the emergency department (ED). Patients with CP symptomatic after sublingual nitroglycerin (SL NTG) therapy with a systolic blood pressure (SBP) greater than 95 mmHg were included. Patients were treated with i.v. NTG boluses of 0.05 mg to 0.4 mg during a 1- to 2-minute period per a protocol based on the patient's prebolus SBP. This was followed by a maintenance infusion. Additional NTG boluses were repeated every 5 minutes as needed. The end point of treatment was the resolution of chest discomfort, thrombolysis, or a SBP less than 95 mmHg. There were 16 cases of CP. All 16 patients treated, ie, 5 with acute myocardial infarction and 11 with unstable angina showed significant decrease in chest discomfort after 1 to 2 boluses. Two of five with acute myocardial infarction and 9 of 11 patients with unstable angina had complete relief of chest pain after 1 to 4 boluses. There were no episodes of hypotension (SBP < 90 mmHg) in any of the 16 cases. The judicious use of i.v. NTG boluses administered during a 1- to 2-minute period, in the ED, appears safe and efficacious in patients with CP unresponsive to SL NTG therapy.

Administration, Sublingual↗
PubMed1994

Alkalinization of local anesthesia with sodium bicarbonate--preferred method of local anesthesia.

Effective anesthetic techniques include local anesthetic infiltration with or without sedation and general anesthesia. Local anesthesia is a safe and effective anesthetic technique, that when performed properly is applicable to many outpatient urologic procedures. We have found that the pain usually associated with intradermal injection of lidocaine is attenuated by the addition of sodium bicarbonate.

Anesthesia, Local↗
PubMed1994

Biochemical effects of a calcium supplement in postmenopausal women with primary hyperparathyroidism.

Oral calcium loading is known to decrease parathyroid hormone levels in primary hyperparathyroidism. We have examined the effects of a calcium supplement on bone resorption in postmenopausal primary hyperparathyroidism. Fasting blood and urine samples were obtained in 12 postmenopausal women (median age 64 yr) with primary hyperparathyroidism associated with mild hypercalcemia (plasma calcium < 3.00 mmol/l). Further samples were obtained 12 hours after a 1 g calcium supplement given at 2100 h. After calcium administration there were rises in plasma ionized calcium (p < 0.02), plasma phosphate (p < 0.05) and the renal tubular maximum reabsorption capacity for phosphate (p < 0.01) and falls in parathyroid hormone (p < 0.05) and the renal tubular maximum reabsorption capacity for calcium (p < 0.05). The urinary calcium/creatinine increased (p < 0.01) and the urinary hydroxyproline/creatinine (p < 0.02) fell. These results indicate that calcium loading inhibits bone resorption in postmenopausal women with mild primary hyperparathyroidism.

Absorption↗
PubMed1994

Oral calcium suppresses biochemical markers of bone resorption in normal men.

Calcium supplementation decreases bone resorption and retards bone loss in women. There is little information about the effects of calcium supplementation in men. The effects of a 1-g oral calcium load at 0900 on bone-related biochemical variables were evaluated in 13 normal men (aged 51-70 y). Calcium administration was associated with increases in plasma ionized calcium (P < 0.001) and urinary calcium (P < 0.001), and a decrease in plasma parathyroid hormone (P < 0.001). There was a nonsignificant trend (r = -0.47, P = 0.11) for the decrease in plasma parathyroid hormone to be related to radiocalcium absorption. After the calcium load there were decreases in the urinary hydroxyproline-creatinine ratio from 11 +/- 1.1 to 7.9 +/- 0.6 (P < 0.01), the urinary deoxypyridinoline-creatinine ratio from 14.0 +/- 1.8 to 10.1 +/- 0.9 (P < 0.05), and the urinary pyridinoline-creatinine ratio from 52 +/- 5 to 40 +/- 3 (P < 0.01) between baseline and 6 h. There was no change in plasma osteocalcin. These observations indicate that a 1-g calcium load suppresses biochemical markers of bone resorption for > or = 6 h in normal men and support the concept that calcium supplementation may be useful in the prevention of bone loss in men.

Absorption↗
PubMed1994

Renal leak of calcium in post-menopausal osteoporosis.

BACKGROUND: Urine calcium after an overnight fast is higher in osteoporotic than in normal post-menopausal women. The question is whether this is the cause or effect of the bone-losing state. OBJECTIVE: To establish whether the elevated obligatory calcium loss in osteoporotic women is due to a raised filtered load of calcium or to reduced renal tubular reabsorption of calcium. DESIGN: Covariance analysis using total plasma calcium and its fractions as the covariates. PATIENTS: Eighty-two untreated post-menopausal women without vertebral compression and 137 untreated post-menopausal with vertebral compression all between the ages of 61 and 75 years. MEASUREMENTS: After an overnight fast, calcium, albumin, globulins, anion gap and bicarbonate were measured in the plasma, and calcium, sodium and creatinine in the urine. The calcium fractions in plasma and the calcium/creatinine and sodium/creatinine ratios in urine were calculated. Bone density was measured in the distal forearm. RESULTS: The ultrafiltrable and ionized calcium in the plasma and the calcium/creatinine ratio in the urine were significantly higher in the women with vertebral compression than in those without. On covariance analysis, neither total plasma calcium nor any of the plasma calcium fractions made a significant contribution to the difference in fasting urine calcium between normal and osteoporotic women, whether bone status was defined by vertebral compression or by bone density. CONCLUSIONS: The increased obligatory calcium loss in osteoporotic women is not due to an increase in the filtered load of calcium and must therefore reflect reduced renal tubular reabsorption. This implies that the calcium loss in the urine is not the result of increased bone resorption but is more likely to be causal.

Aged↗
PubMed1994

Postprandial antropyloroduodenal motility and gastric emptying in gastroparesis--effects of cisapride.

There is little information about the organisation of antroduodenal contractions or pyloric motility in patients with gastroparesis. The mechanisms responsible for the acceleration of gastric emptying by cisapride in patients with gastroparesis are also poorly understood. Simultaneous manometric and scintigraphic recordings were performed in 12 patients with gastroparesis and nine healthy volunteers before and after cisapride administration. Antropyloroduodenal pressures were recorded with a sleeve/side hole manometric assembly and gastric emptying with a scintigraphic method. Thirty minutes after the solid component of the test meal had begun to empty from the stomach all subjects received 5 mg cisapride intravenously over 10 minutes and recordings continued for a further 60 minutes. In the 30 minutes before cisapride there was no significant difference in the number of antral pressure waves (median 20 v 33, NS), basal pyloric pressure, or the number of isolated pyloric pressure waves between patients and volunteers, but the number of antral waves of extent > or = 6 cm (median 1 v 5, p < 0.05) was less in the patients, as was gastric emptying (8% v 20%, p < 0.05). In the patients, there was no change in the number of antral waves after cisapride, but there was an increase in the number of antral waves > or = 6 cm in extent (median 7 v 1, p < 0.05) and in the rate of gastric emptying (26% v 8%, p < 0.01). In the healthy subjects, cisapride increased gastric emptying (31% v 20%, p < 0.05), but reduced the number of antral waves (10 v 33, p < 0.05). Cisapride had no significant effect on the number of antral waves of extent more than or equal to 6 cm (11 v 5, NS). The number of isolated pyloric pressure waves decreased after cisapride (4 v 11, p < 0.05). There was a relationship between gastric emptying and the number of antral pressure waves of extent more than or equal to 6 cm in both the patients (r=0.38, p<0.05) and healthy subjects (r=0.05, p<0.01). There was no significant relationship between gastric emptying and the number of antral waves. It is concluded that disturbance of the relationship between antral, pyloric, and duodenal pressure waves is a major abnormality of postprandial gastric motor function in patients with gastroparesis. The stimulation of antral pressure waves of extent more than or equal to 6 cm may contribute to the acceleration of gastric emptying produced by cisapride in patients with gastroparesis and in normal subjects.

Adult↗
PubMed1994

Modulation of food intake by peripherally administered amylin.

Amylin has been demonstrated to produce anorexia in rodents. Its mechanism of action is unknown. We have studied the effect of amylin on food intake in mice in a variety of paradigms to determine whether it inhibits food intake by a peripheral mechanism of action. In addition, we determined its effect in genetically obese mice models and whether its effects differed in aged mice. Cholecystokinin is the prototypic satiety agent. The effects of amylin on reducing food intake were not attenuated by the cholecystokinin antagonist L-364718, suggesting that it does not produce its effect through the release of cholecystokinin. A number of gastrointestinal peptides produce anorexia by stimulating ascending vagal fibers. For this reason, we studied the effect of truncal vagotomy on the suppression of feeding induced by amylin. Vagotomy did not prevent amylin from inhibiting food intake. Amylin was equally effective at reducing food intake in genetically obese (ob/ob) and lean (ob/c) mice and in diabetic (db/db) and lean (db/c) mice. Amylin effectively suppressed food intake in mice over the age of 4-22 mo. These studies further support the role of the pancreatic hormone amylin as a peripherally acting satiety agent.

Amyloid↗
PubMed1994

Plasma volume conservation in pigeons: effects of air temperature during dehydration.

We assessed the effects of the ambient air temperature prevailing during dehydration, which included complete water and food deprivation, on plasma volume (PV) conservation in pigeons (Columba livia) exposed to air temperatures of 25 degrees C (n = 7), 36 degrees C (n = 12), and 40 degrees C (n = 24). The pigeons were dehydrated for 65.4, 32.3, and 27.7 h, on average, at 25, 36, and 40 degrees C, respectively. Dehydration rates averaged 5, 10, and 15.2% of initial total body water (TBW) per day at the three air temperatures, in ascending order. Birds exposed to 25 and 36 degrees C maintained PV despite the fact that they lost, on average, 14 and 17.3% of their TBW, respectively. In contrast, PV in pigeons exposed to 40 degrees C decreased by 8.9%, even though the reduction in TBW (17.7%) was similar to that incurred at 36 degrees C. Mean plasma osmolalities reached 347.7, 345.6, and 374.8 mosmol/kgH2O at 25, 36, and 40 degrees C, respectively. No significant changes occurred in hematocrit (Hct) and hemoglobin concentrations (Hb) during dehydration at 25 and 36 degrees C. However, at 40 degrees C Hb increased by 8.2% with no change in Hct, indicating a decrease in red blood cell volume (RBCV). The results of this study suggest that maintenance of PV and RBCV is affected not only by the dehydration level attained but also by the ambient conditions under which dehydration is induced and the rate at which dehydration takes place.

Animals↗
PubMed1994

Stereospecific effects of intraduodenal tryptophan on pyloric and duodenal motility in humans.

BACKGROUND: L-Tryptophan delays gastric emptying in animals to a greater extent than D-tryptophan, but none of the possible motor mechanisms responsible for this stereospecific effect have been evaluated. METHODS: In 11 healthy volunteers antropyloroduodenal pressures were recorded in the fasted state with a sleeve/sidehole manometric assembly during 20-min intraduodenal infusions (2 ml.min-1) of isotonic L- and D-tryptophan (50 mM, pH 5.7) and normal saline (pH 5.5), given in randomized order. RESULTS: Intraduodenal L-tryptophan increased basal pyloric pressure (p < 0.05), whereas D-tryptophan had no effect. In contrast, L- and D-tryptophan both stimulated (p < 0.05) localized phasic pyloric pressure waves, and there was no significant difference in the responses. The number of duodenal pressure waves was greater during infusion of L-tryptophan than during D-tryptophan (p < 0.05). CONCLUSION: We conclude that intraduodenal tryptophan has stereospecific effects on pyloric and duodenal motility. Although the precise contribution of these differential effects to gastric emptying remains to be clarified, they may be partially responsible for the differences in gastric emptying of D-tryptophan and L-tryptophan.

Adult↗
PubMed1994

Treatment of osteoporosis in the elderly.

Fracture risk is adversely related to bone density, wherever it is measured. Women should be screened by bone densitometry around the time of the menopause and treated with calcium or hormones if the density is low. Women with vertebral compression should be treated with calcitriol if calcium absorption is low, with hormones if urine calcium is high, and with calcitriol and hormones if both abnormalities are present. It is uncertain whether newer treatments offer any advantages over this regimen. Vitamin D is indicated in household individuals or others with low levels of 25 OHD to prevent loss from secondary hyperparathyroidism and perhaps also to improve muscle power.

Aged↗
PubMed1994

Primary hyperparathyroidism.

Primary hyperparathyroidism is not rare. It is particularly common after the age of 50 and may affect up to 3% of postmenopausal women. It is commonly found as a result of blood tests performed for other reasons and is therefore often asymptomatic. Surgical treatment is recommended for patients with renal stone disease, plasma calcium above 3 mmol/L and accelerated bone loss (e.g., bone density < 3 standard deviations below the young normal mean). There is considerable debate about whether mild asymptomatic disease should be treated, but if there is rapid bone loss, either surgical or medical therapy with hormones or bisphosphonates is indicated.

Aging↗