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Biomedical subjects

R M Navari

Publications and source records attributed to R M Navari.

At least 19 recordsLinked to original sources
PubMed1992

Stratified, randomized, double-blind comparison of intravenous ondansetron administered as a multiple-dose regimen versus two single-dose regimens in the prevention of cisplatin-induced nausea and vomiting.

PURPOSE: This study compares the efficacy and safety of two single-dose regimens with the approved three-dose regimen of ondansetron in the prevention of cisplatin-induced emesis. PATIENTS AND METHODS: This multicenter study was a stratified, randomized, double-blind, and parallel group design. Chemotherapy-naive inpatients were randomized to receive intravenous (IV) ondansetron (Zofran; Glaxo Inc, Research Triangle Park, NC) 0.15 mg/kg times three doses, every 4 hours or a single 8-mg or 32-mg dose followed by two saline doses that began 30 minutes before cisplatin administration. Cisplatin (high-dose > or = 100 mg/m2 or medium-dose 50 to 70 mg/m2) was given as a single infusion (< or = 3 hours). Patients were monitored for emetic episodes, adverse events, and laboratory safety parameters for 24 hours after cisplatin administration. RESULTS: A total of 699 patients (359 high-dose, 340 medium-dose) were enrolled. Of these, 618 were assessable for efficacy (15 ineligible, 66 protocol deviations). The 32-mg dose was superior to the 8-mg single dose with regard to total number of emetic episodes (high-dose, P = .015; medium-dose, P < .001), complete response (no emetic episodes: high-dose, 48% v 35%; P = .048; medium-dose, 73% v 50%; P = .001) and failure rate (> 5 emetic episodes, withdrawn or rescued: high-dose, 20% v 34%; P = .018; medium-dose, 9% v 23%; P = .005). The 32-mg single dose was also superior to the 0.15 mg/kg times three dose regimen with regard to total number of emetic episodes (medium-dose, P = .033) and failure rate (high-dose, 20% v 36%; P = .009; medium-dose, 9% v 22%; P = .011). Ondansetron was well tolerated. The most common adverse event was headache. An approximate 10-fold increase in the incidence of clinically significant transaminase elevations was observed in the high-dose versus medium-dose cisplatin strata (aspartate aminotransferase [AST], 6.5% v 0.7%; serum alanine aminotransferase [ALT], 5.0% v 0.3%). CONCLUSION: A 32-mg single dose of ondansetron is more effective than a single 8-mg dose and is at least as effective as the standard regimen of 0.15 mg/kg times three doses in the prevention of cisplatin-induced acute emesis.

Adult↗
PubMed1991

Specificity of low dose fadrozole hydrochloride (CGS 16949A) as an aromatase inhibitor.

CGS 16949A (fadrozole hydrochloride), a potent cytochrome P450-mediated steroidogenesis inhibitor, blocks aromatase at low doses, but other biosynthetic steps at higher concentrations. Recent studies demonstrated inhibition of C11-hydroxylase, corticosterone methyloxidase-II, and deoxycorticosterone to corticosterone conversion with this agent at some-what higher concentrations than those required for blockade of aromatase. Based upon phase I studies, we postulated that relatively selective inhibition of aromatase might be possible if sufficiently low doses of CGS 16949A were used. A phase II study in 54 postmenopausal women with metastatic breast cancer examined the effects of low dose CGS 16949A on estrogen, mineralocorticoid, and glucocorticoid secretion. Two dose schedules and two dose levels were chosen based upon our prior dose escalation protocol study. Plasma estrone, estradiol, and estrone sulfate as well as urinary estrone and estradiol fell equally with 1.8-4 mg CGS 16949A given either on a twice daily or three times daily dose schedule. Isotopic kinetic studies demonstrated an 84% decrease in the rate of conversion of androstenedione to estrone to 0.40 +/- 0.07% (patients receiving 1.8-4 mg CGS 16949A daily). With these three regimens, basal levels of aldosterone and cortisol did not change significantly over a 12-week period of observation. Clinical examination, plasma electrolytes, and urinary sodium/potassium ratios suggested no biological evidence of mineralo-corticoid deficiency. ACTH-stimulated cortisol concentrations, however, were blunted at each dose level compared to pretreatment values. Nonetheless, peak responses exceeded 550 nmol/L, or a basal to peak difference of 190 nmol/L or greater, in 97% of instances. This probably reflected inhibition of C11-hydroxylase, since basal and ACTH-stimulated levels of 11-deoxycortisol were increased in response to CGS 16949A. Androstenedione and 17 alpha-hydroxyprogesterone also exhibited an upward trend in response to drug treatment. ACTH-stimulated aldosterone levels were blunted to a greater extent than those of cortisol, probably as a reflection of corticosterone methyloxidase type II blockade. Overall, the results suggest that CGS 16949A, at doses of 1.8-2 mg daily, blocks aromatase effectively and does not produce clinically important inhibition of cortisol or aldosterone biosynthesis. Thus, this agent can probably be used safely without glucocorticoid or mineralocorticoid supplementation.

17-alpha-Hydroxyprogesterone↗
PubMed1989

Comparison of intermittent versus continuous infusion metoclopramide in control of acute nausea induced by cisplatin chemotherapy.

Sixty previously untreated patients with newly diagnosed advanced-stage lung cancer (21 small-cell, 39 non-small-cell) received chemotherapy with cisplatin and etoposide. Bleomycin was also used in the patients with non-small-cell lung cancer. During the first cycle of chemotherapy, 30 patients received antiemetic therapy with intermittent metoclopramide (regimen A), and the other 30 patients received continuous infusion metoclopramide (regimen B). During the second course of chemotherapy, patients were switched to the alternate regimen. Regimen A consisted of lorazepam, 1 mg, orally; dexamethasone, 10 mg, intravenously (IV) every four hours for three doses; diphenhydramine, 0.5 mg/kg, IV every four hours for three doses; metoclopramide, 1 mg/kg, IV bolus every two hours for six doses. Regimen B was identical to A except metoclopramide was administered as 1 mg/kg, IV bolus followed by 0.5 mg/kg/h for ten hours. Fifty-eight patients completed both antiemetic regimens. Thirty-nine of the 58 patients had total control of acute nausea and vomiting (0-1 episodes) with regimen A or B. Fourteen patients had poor control of acute nausea and vomiting (more than one episode) with regimen A but total control with regimen B. Five patients had poor control with either regimen. Dystonic reactions, akathisia, or diarrhea occurred in 20 of the 58 patients on regimen A, but in only eight of the 58 patients on regimen B. Compared with intermittent bolus, continuous infusion metoclopramide is more effective in total control of acute nausea and vomiting and has less toxicity.

Carcinoma, Non-Small-Cell Lung↗
PubMed1984

Prophylaxis of infection in patients with aplastic anemia receiving allogeneic marrow transplants.

One hundred one patients with severe aplastic anemia underwent allogeneic marrow transplantation and received one of three forms of infection prophylaxis: oral nonabsorbable antibiotics and isolation and decontamination in a laminar airflow room (36 patients); prophylactic granulocyte transfusions from a single family member donor (33 patients); or conventional treatment in single rooms with hand-washing and mask precautions (31 patients). During the period of granulocytopenia, patients in the laminar airflow rooms acquired fewer infections than either of the other groups, but this difference was statistically significant only when compared with the group receiving conventional treatment. Patients in the laminar airflow rooms had significantly fewer infections after engraftment as compared with the other two groups. Incidence of interstitial pneumonia and graft rejection was not different among the three groups. Acute graft-versus-host disease occurred later (Day 47) in the group in the laminar airflow rooms as compared with the group receiving prophylactic granulocyte transfusions (Day 23) or the group receiving conventional treatment (Day 20). The incidence of grades II to IV acute graft-versus-host disease was less in the patients in the laminar airflow rooms but only reached borderline significance (p = 0.08) when compared with the conventionally treated patients. The survival at Day 100 was 92 percent for the group in the laminar airflow rooms, 79 percent for the group receiving prophylactic granulocyte transfusions, and 64 percent for the group receiving conventional treatment.

Adolescent↗
PubMed1984

Hypothermia.

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Adolescent↗
PubMed1983

Mycobacterial infections in marrow transplant patients.

Bone marrow transplant recipients undergo ablation of host immune defenses with total-body irradiation or high dose chemotherapy, or both. Over a 5.6-year period, mycobacterial infections were observed in 7 of 682 patients with leukemia who received marrow grafts. Four patients had pulmonary and three extrapulmonary infection. Granulomas were observed in the lungs of three patients, in the liver of one patient, and in the skin of one patient. Cultures revealed Mycobacterium tuberculosis in two patients, Mycobacterium fortuitum in two patients, and Mycobacterium kansasii in one patient. In the six patients treated with antimycobacterial therapy in either the pretransplant or posttransplant period, complete resolution of the infection was achieved. Pretransplant chest radiograph abnormalities suggesting mycobacterial infections should be aggressively evaluated in these immunocompromised hosts. Prophylaxis should be considered in marrow graft recipients with a well-established history of inadequately treated tuberculosis, previous Bacille Calmette-Guerin immunotherapy, known family contacts, recent skin test conversion, or past skin test positivity.

Adolescent↗
PubMed1983

Bone marrow necrosis in acute leukemia.

2 patients with premortem marrow necrosis in acute leukemia are discussed. A review of the course of each patient plus those in the literature suggests that premortem marrow necrosis may not be a poor prognostic sign in acute lymphoblastic leukemia but generally precedes a prolonged and fatal pancytopenia in acute myelogenous leukemia. The technetium-99m rhenium sulfur colloid marrow scan was found to be of value in assessing the extent and degree of necrosis of the marrow as well as in documenting and predicting marrow recovery following chemotherapy.

Aged↗
PubMed1979

Oxygen consumption of pial arteries.

Pial arterioles and arteries, normally responsive to alterations in PaCO2, were obtained by microdissection from the parietal cortex of 53 anesthetized cats. The oxygen consumption of these vessels, determined with the Cartesian diver microrespirometer, was found to be size dependent. It increased progressively from vessels 60 mum in diameter to vessels 250 mum in diameter. In vessels 250--375 mum in diameter there was a progressive decrease in oxygen consumption with increasing vessel size. The oxygen consumption was not altered by increasing the oxygen concentration in the diver from 20% to 95%, or that of glucose from 1.1 to 2.0 mM. Planimetry of histological sections showed that the percentage of endothelium and smooth muscle increased as vessel diameter increased from 60 to 200 mum, and thereafter decreased with increasing vessel size. When these differences in the composition of the vessel wall were taken into account, there was still residual dependence of the oxygen consumption on vessel diameter. This may represent intrinsic differences in the metabolic rate of vascular smooth muscle in vessels of different size.

Animals↗
PubMed1978

Responses of cerebral arteries and arterioles to acute hypotension and hypertension.

The responses of cerebral precapillary vessels to changes in arterial blood pressure were studied in anesthetized cats equipped with cranial windows for the direct observation of the pial microcirculation of the parietal cortex. Vessel responses were found to be size dependent. Between mean arterial pressures of 110 and 160 mmHg autoregulatory adjustments in caliber, e.g., constriction when the pressure rose and dilation when the pressure decreased, occurred only in vessels larger than 200 micron in diameter. Small arterioles, less than 100 micron in diameter, dilated only at pressures equal to or less than 90 mmHg; below 70 mmHg their dilation exceeded that of the larger vessels. When pressure rose to 170- 200 mmHg, small vessels dilated while the larger vessels remained constricted. At very high pressures (greater than 200 mmHg) forced dilation was frequently irreversible and was accompanied by loss of responsiveness to hypocapnia. Measurement of the pressure differences across various segments of the cerebral vascular bed showed that the larger surface cerebral vessels, extending from the circle of Willis to pial arteries 200 micron in diameter, were primarily responsible for the adjustments in flow over most of the pressure range.

Animals↗
PubMed1978

Role of tissue hypoxia in local regulation of cerebral microcirculation.

The mechanism of action of hypoxia on cerebral blood vessels and its role in the regulation of the cerebral circulation were investigated in anesthetized cats. Arterial hypoxia produced marked cerebral arteriolar vasodilation, which was partially reversed by perfusing the space under the cranial window with artificial cerebrospinal fluid (CSF) containing 6-94% oxygen. More marked increase in the local supply of oxygen, via perfusion of the space under the cranial window with fluorocarbon FC-80 equilibrated with 100% oxygen, completely eliminated the vasodilation induced by arterial hypoxia. Fluorocarbon equilibrated with 100% N2 had no effect on the vasodilation. The vasodilation associated with hypotension was completely reversed by perfusion with fluorocarbon equilibrated with 100% oxygen and was unaffected by perfusion with fluorocarbon or CSF equilibrated with gas not containing oxygen. The vasodilation associated with Metrazole-induced seizures was partially reversed by perfusion with fluorocarbon containing oxygen. The results show that hypoxia dilated cerebral blood vessels entirely via a local mechanism, that hypoxia is the dominant mechanism involved in the vasodilation associated with hypotension, and that it is, at least partially, responsible for the vasodilation associated with seizures.

Animals↗
PubMed1978

Inhibition of rat bronchiolar oxygen consumption by plasma proteins.

The oxygen consumption of rat bronchioles suspended in a physiological salt solution containing plasma proteins was measured with the Cartesian diver microrespirometer. The oxygen consumption of the bronchiolar tissue 100-300 and 300-400 micrometer in diam was significantly (P greater than 0.01) reduced as the protein concentration of the suspending solution was increased from the low to the high extreme of the normal plasma physiological range and as the diffusion distance through the suspending medium was increased from 25 to 50 micrometer. The reduction in the bronchiolar oxygen consumption was significantly (P greater than 0.01) reversed by using 95% oxygen-5% nitrogen instead of air as the diffusing gas in the Cartesian diver. Measurements of the oxygen diffusivity in the protein solutions using a diaphragm diffusion cell showed a large decrease in the diffusivity as the plasma protein concentration was increased over the same concentration range used in the oxygen consumption studies. These results suggest that the reduction in oxygen consumption was secondary to a decrease in oxygen diffusion and may provide at least a partial explanation for the diffusion abnormalities which exist in noncardiogenic pulmonary edema in which there is an increase in microvascular membrane permeability to proteins.

Animals↗
PubMed1977

Mass transfer properties of gases in fluorocarbons.

The solubility and diffusion coefficient of oxygen and carbon dioxide were measured in both the pure and emulsified of two fluorocarbons, perfluorotributylamine and perfluorobutyl perfluorotetrahydrofuran. The solubility coefficient and the diffusivity of oxygen in the pure form of the fluorocarbons decreased with decreasing partial pressure of Oxygen (PO2), but the solubility coefficient and the diffusivity of carbon dioxide were independent of its partial pressure. The solubility and diffusion of oxygen in the emulsified form of the fluorocarbons followed the pattern expected from the behavior of oxygen in the pure fluorocarbon. The experimental results suggest that there exists a physical and/or chemical interaction between oxygen and the fluorocarbons, and this interaction is more pronounced at partial pressures below 150 mm Hg. Comparisons of the oxygen content in the fluorocarbon emulsions with that in whole blood show that at PO2 of 760 mm Hg, the oxygen content in the fluorocarbon emulsions is approximately one-half that in whole blood, but at PO2 of 50-150 mm Hg, the oxygen content in the emulsions decreases to values which are less than one-tenth that of whole blood.

Carbon Dioxide↗