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Biomedical subjects

S Hurwitz

Publications and source records attributed to S Hurwitz.

At least 163 records · Page 9Linked to original sources
PubMed1984

Prolonged granulocytopenia: the major risk factor for invasive pulmonary aspergillosis in patients with acute leukemia.

A case-control study of patients with acute leukemia was done to identify significant risk factors for invasive pulmonary aspergillosis by reviewing the medical histories of 15 cases of pathologically proven invasive pulmonary aspergillosis and 45 controls. A history of lung or sinus disease, smoking, and multiple recurrences of leukemia did not increase the risk of invasive pulmonary aspergillosis. Cases and controls received similar chemotherapeutic regimens, and exposure to aminoglycosides, carbenicillin, trimethoprim-sulfamethoxazole, or corticosteroids was not significantly associated with development of invasive pulmonary aspergillosis. Among the factors tested, only granulocytopenia was associated with development of invasive pulmonary aspergillosis. Early in the course of granulocytopenia, patients developed signs of invasive pulmonary aspergillosis at a rate of approximately 1% per day. As the duration of granulocytopenia increased, the rate increased, approximating 4.3% per day between the 24th and 36th days. Of the 13 patients remaining granulocytopenic at 28 days, 7 had developed signs of invasive pulmonary aspergillosis. For patients with acute leukemia, granulocytopenia persisting longer than three weeks is the major risk factor for developing invasive pulmonary aspergillosis.

Acute Disease↗
PubMed1983

Induced changes in the affinity of 1,25-dihydroxyvitamin D3 receptors in chick intestine.

The contents of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in plasma and intestinal mucose were increased by dietary calcium and by dietary phosphorus restriction. The concentration of intestinal occupied receptors for 1,25(OH)2D3 was higher in calcium-restricted birds. The affinity (association constant) of intestinal receptors for 1,25(OH)2D3 was lower in phosphorus-restricted chicks, as compared to control or calcium-restricted chicks. The number of binding sites were not influenced by dietary calcium or phosphorus restriction.

Animals↗
PubMed1983

Lung cancer resectability in urban Blacks.

Two hundred and eighty-one patients with carcinoma of the lung were seen over a period of 30 months in our unit. All patients were investigated and staged according to the system of the American Joint Committee for Cancer Staging. Patients with stage I or stage II disease were operated upon, but those with stage III disease or with a pre-operative diagnosis of small cell tumour were not considered for surgery. Of the 281 patients evaluated, 83 (29,5%) underwent thoracotomy and 55 (19,6%) resection.

Black or African American↗
PubMed1983

Urinary cyclic AMP excretion in birds: dependence on parathyroid hormone activity.

The cyclic AMP response of avian kidney to parathyroid activity has been evaluated both in vitro and in vivo. The production of cyclic AMP by dispersed avian kidney cells was stimulated by bovine parathyroid hormone or by an extract of avian parathyroid glands. Intravenous infusion of bovine parathyroid hormone resulted in increased urinary excretion and plasma concentration of cyclic AMP, as well as increased plasma calcium and urinary phosphorus excretion. The increases in plasma and urinary cyclic AMP preceded those of plasma calcium and of phosphorus excretion. EDTA infusion resulted in a decrease in plasma calcium and an increase in urinary cyclic AMP excretion. After 10 days on a low-calcium diet, chickens exhibited a 4.5-fold increase in urinary cyclic AMP excretion. The results suggest that urinary cyclic AMP in chickens reflects PTH activity similar to some mammalian species.

Animals↗
PubMed1983

Handling of water and dietary monovalent ions by the young turkey.

Sodium and water turnover rates were measured in young turkeys fed diets with three concentrations of NaCl and kept at 12, 18 or 30 degrees C. Sodium absorption averaged approximately 60% and was unaffected by temperature. Water and sodium pools were affected by temperature and sodium intake. Water turnover was linear to sodium turnover at the lower two temperatures. No significant relationship was apparent in birds kept at 30 degrees C. The reciprocal of the slope of the function of water turnover on sodium turnover was 125-170 mM, suggesting an increase in isotonic urine excretion with sodium intake and a corresponding increase in water intake. Dietary sodium and potassium stimulated water turnover similarly. Dietary chloride concentration did not affect water turnover. In the turkey plasma pH and pCO2 were unaffected by a wide range of the anion-cation balance. It is concluded that excess sodium or potassium intakes is handled effectively in the turkey by increased water intake and excretion.

Animals↗
PubMed1983

Patterns of congenital nevocellular nevi. A histologic study of thirty-eight cases.

A series of thirty-eight cases of congenital nevocellular nevi were excised and studied histologically. Depending on the extent of nevoid cell dermal infiltration, four histologic patterns were observed: diffuse or patchy infiltration of the upper dermis alone, or diffuse or patchy infiltration of the upper and deep dermis with nevoid cells in or below the lower one third of the reticular dermis. Nevoid cells extended into the deepest reticular dermis in only 37% of these patients. There was no significant correlation between the four histologic patterns and age, sex, location, or lesion size. Two cases recurred after surgery but none underwent malignant change. The patients who developed recurrent nevi in the surgical site postexcision manifested the diffuse upper and deep dermal pattern of nevoid cell infiltration. We interpret this observation as due to incomplete excision of the primary lesion, reflecting the difficulty of removing congenital nevi with this histologic pattern. We conclude from this study that: (1) congenital nevocellular nevi show at least four typical histologic patterns; (2) the nevoid cells of congenital nevi do not necessarily extend into the deep dermis; and (3) of the four histologic patterns seen in congenital nevi, that one showing diffuse and deep placement of nevoid cells on biopsy requires more aggressive excision to prevent recurrence.

Adolescent↗
PubMed1983

Simulation of calcium homeostasis: modeling and parameter estimation.

The system that regulates plasma calcium in the bird has been formalized into a model based on a series of differential equations and solved by computer simulation. Bone, kidney, and intestine have been considered as the control subsystems, with parathyroid hormone and 1,25-dihydroxycholecalciferol as the regulating hormones. The parameters used in the simulation model have been computed either from published results or by specifically designed experiments described here. For the estimation of parameters, an iterative procedure has been developed that was designed to minimize the sum of square errors between observed and system-simulated values. Parameters of 1,25-dihydroxycholecalciferol metabolism were experimentally obtained from the kinetic behavior of the 3H-labeled hormone in rachitic birds after a single dose. Model parameters have been adjusted using the results of in vivo calcium loading and validated by an EDTA infusion experiment. The simulation model has been used to study the hierarchy of the activities of the three control subsystems and of the regulating hormones, at different calcium intakes. Positive or negative errors in plasma calcium resulted in an asymmetry in the activities of the controlling systems, bone and kidney, whereas the intestine is characterized by its relatively long response time.

Animals↗
PubMed1983

The response of growing turkeys to dietary nutrient density.

The response to diets of different nutrient densities was evaluated in male turkeys. In 2-week experiments with 1-week-old and 14-week-old turkeys the growth response to nutrient density appeared to be biphasic with an accelerated response at the lower and a much smaller response at the upper range of nutrient density. Results suggest that the upper limit of nutrient density for obtaining the accelerated growth response was higher for older (14-week-old) than for younger (1-week-old) birds. In two additional experiments, the growth response at the upper energy range was estimated at 1 to 2% per 100 kcal. In 14-week-old turkeys, abdominal fat did not change with nutrient density.

Age Factors↗
PubMed1983

Performance and energy needs of 20-week-old male turkeys at different environmental temperatures.

Performance of male 20-week-old B.U.T. turkeys at different environmental temperatures was evaluated. Weight gain was severely depressed by a constant 35 C but was also lower at 27 C than at 10 and 20 C. Feed efficiency hardly changed between 10 and 20 C but was depressed at the higher temperatures. The calculated energy needs for maintenance were only slightly reduced at 20 C compared with 10 C, but they declined continuously with an increase in temperature up to 35 C.

Animals↗
PubMed1983

The amino acid requirements of growing turkeys. 1. Model construction and parameter estimation.

A model has been formulated to calculate the protein and amino acid requirements for growing turkeys. A requirement was taken as the sum of the needs for maintenance, for gain in carcass weight without feathers, and for the feathers. Parameters used in the model were obtained from a study of carcass composition along the growth period and from two balance trials with adult turkeys. The maintenance requirement was considered to be the sum of the needs for replacing skin and intestinal protein losses and for the obligatory creatinine excretion in the urine. Nitrogen retention was determined at 2.3 g/day in protein-fed adult (17 kg) male turkeys as an estimate for the replacement needs for skin protein loss. Creatinine excretion in these birds was 123 mg/day. When fed an N-free diet, 16.5 kg adult turkeys excreted a total of 3.5 g/day amino acids as a result of intestinal losses. The protein requirement for maintenance was estimated at 32 mg/day/g2/3 of body weight by summing up the different needs and dividing by .85, the coefficient of protein absorption. Protein and amino acid analyses of nude carcass and feathers and the growth curve were used to calculate the requirements for growth. These were then related to energy intake predicted by equations, which included previously determined coefficients for maintenance and growth (Hurwitz et al., 1980a), and the results of carcass lipid analysis. The calculated amino acid requirements were similar to those of the National Research Council (1977).

Amino Acids↗