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Biomedical subjects

S K Puri

Publications and source records attributed to S K Puri.

At least 55 records · Page 3Linked to original sources
PubMed1997

Sterile protection of monkeys against malaria after administration of interleukin-12.

An estimated 300-500 million new infections and 1.5-2.7 million deaths attributed to malaria occur annually in the developing world, and every year tens of millions of travelers from countries where malaria is not transmitted visit countries with malaria. Because the parasites that cause malaria have developed resistance to many antimalarial drugs, new methods for prevention are required. Intraperitoneal injection into mice of one dose of 150 ng (approximately 7.5 micrograms per kg body weight) recombinant mouse interleukin-12 (rmIL-12) 2 days before challenge with Plasmodium yoelii sporozoites protects 100% of mice against malaria. We report that one subcutaneous injection of 10 micrograms/kg recombinant human IL-12 (rhIL-12) 2 days before challenge with P. cynomolgi sporozoites protected seven of seven rhesus monkeys. Protection was associated with marked increases in plasma levels of interferon-gamma (IFN-gamma), and relative increases of lymphoid cell messenger RNA coding for IFN-gamma and several other cytokines. We speculate that rIL-12 protects monkeys through IFN-gamma-dependent elimination of P. cynomolgi-infected hepatocytes. This first report of rIL-12-induced protection of primates against an infectious agent supports assessment of rhIL-12 for immunoprophylaxis of human malaria.

Animals↗
PubMed1996

Sodium beta-artelinate--a new potential gametocytocide.

The water-soluble artemisinin analogue sodium beta-artelinate, a fast-acting blood schizontocide, was evaluated for gametocytocidal action against simian malaria Plasmodium cynomolgi B, and a single dose of the compound has been found to be an effective gametocytocide by both oral and intravenous routes. The compound was able to sterilize the circulating gametocytes in rhesus monkey, resulting in loss of mosquito infectivity and oocyst development in the Anopheles stephensi. However, no sporontocidal action has been observed with this compound.

Administration, Oral↗
PubMed1996

Studies on ammonia-metabolizing enzymes during Plasmodium yoelii infection and pyrimethamine treatment in mice.

Blood ammonia content and enzymes involved in ammonia metabolism, namely glutamine synthetase (GS), glutamate dehydrogenase (GDH), monoamine oxidase (MAO), alanine amino-transferase (ALT) and aspartate aminotransferase (AST), were studied in Plasmodium yoelii-infected drug-treated mice tissues. The ammonia content in blood increased with the rise of parasitaemia. Hepatic GS, GDH and MAO showed a marked decrease in enzyme activity during parasitic infection. In contrast, cerebral GS and MAO showed a significant increase during infection. However, the parallel measurement of renal enzymes did not show any noticeable alterations except for ALT and AST. Oral pyrimethamine treatment (10 mg/kg for 4 days) in infected mice (5-10%) returned the altered levels of the above enzymes to almost normal 1 week after the cessation of drug treatment.

Alanine Transaminase↗
PubMed1996

Poly ICLC inhibits Plasmodium cynomolgi B malaria infection in rhesus monkeys.

Prophylatic treatment with a single dose of 1.0 or 2.0 mg/kg (body weight) of polyinosinic-polycytidylic acid stabilized with polylysine and carboxymethylcellulose (Poly ICLC), a potent interferon (IFN) inducer and immune enhancer, 18 h before intravenous inoculation of sporozoites (1.04 x 10(5)-0.70 x 10(6) sporozoites) of Plasmodium cynomolgi B in the rhesus monkey, completely abolished the infectivity of sporozoites. The inhibitory effect of Poly ICLC is dose dependent in monkeys infected with P. cynomolgi B sporozoites. Treatment with lower doses of Poly ICLC (0.5 mg/kg) provided significant protection, but the lowest dose of Poly ICLC used (0.1 mg/kg) failed to provide any protection. Prophylactic treatment with Poly ICLC, however, had no protective effect against trophozoite-induced infection.

Animals↗
PubMed1996

Relationship of MICs to efficacy of cefotaxime in treatment of Streptococcus pneumoniae infections.

In June 1993, the National Committee for Clinical Laboratory Standards (NCCLS) recommended stringent new interpretive guidelines for antibiotics indicated for Streptococcus pneumoniae meningitis. To assess the predictive values of the recommended breakpoints, retrospective data were collected from patients who had S. pneumoniae infections and were treated with cefotaxime monotherapy. Susceptibilities based on the NCCLS interpretative categories were compared with clinical and bacteriologic outcomes. In 76 evaluable patients, the most common infections were bacteremia-septicemia (n = 49), meningitis (n = 37), and lower respiratory tract infection (n = 14). Under the NCCLS breakpoints proposed in 1993, 55 isolates would have been classed as susceptible to cefotaxime (MIC, < or = 0.25 microgram/ml), 18 would have been classed as intermediate (MIC, 0.5 to 1.0 microgram/ml), and 2 would have been classed as resistant (MIC, > or = 2 micrograms/ml). Of 75 cefotaxime-treated patients for whom cefotaxime MICs were recorded, 73 were clinically cured or improved (37 of 37 with meningitis and 36 of 38 with other infections). One case of bacteremia and one case of bone-and-joint infection were scored as therapeutic failures because initial monotherapy had to be modified because of an adverse drug reaction. Excluding these patients, there were 18 patients infected with S. pneumoniae that would have been classed as not fully susceptible (i.e., MICs > or = 0.5 microgram/ml); all of these patients were cured or improved. The results of this analysis demonstrate that successful treatment with cefotaxime did not correlate well with the guidelines for the susceptibility of pneumococcal isolates to either penicillin or cefotaxime established by the 1993 NCCLS breakpoint recommendations. Because of this study and other similar findings, the NCCLS adopted more clinically relevant guidelines in 1994.

Aged↗
PubMed1996

In-vitro cultivation of exoerythrocytic stages of Plasmodium cynomolgi in hepatocytes of Macaca radiata.

Hepatocytes from bonet monkey (Macaca radiata) obtained by perfusion of a liver biopsy were infected in-vitro with Plasmodium cynomolgi bastianellii sporozoites raised in Anopheles stephensi. The development of exoerythrocytic (EE) stages was seen under phase contrast microscope and by Giemsa staining. Multinucleated EE-stages were seen in the cultured hepatocytes on day 7-8 post-sporozoite inoculation.

Animals↗
PubMed1995

Antioxidant effects of pyruvate in isolated rat hearts.

Sprague-Dawley rat hearts were perfused under constant flow conditions, and a balloon was inserted into the left ventricle to measure heart rate (HR) and left ventricular pressures. Left ventricular generated pressure (LVGP) was calculated as peak systolic minus end diastolic pressure. Three substrate groups, pyruvate (5 mM), glucose (15 mM) and octanoate (0.5 mM), were employed. Oxidative stress was induced by perfusion with tertiary-butyl hydroperoxide (tBHP, 0.35 mM, 12 min) followed by 25 min of perfusion with control buffer. Hearts perfused with pyruvate showed no significant decrease in contractile function following tBHP treatment (HR x LVGP = 17666 +/- 585 mmHg/min, initial: 16414 +/- 2083 post-tBHP treatment). Glucose-perfused hearts had an intermediate decrease in function (19174 +/- 828 mmHg/min, initial; 4379 +/- 2083 post-tBHP), while octanoate-perfused hearts recovered no contractile function. Peak release of LDH was lowest in hearts perfused with pyruvate (115 +/- 17 mU/g wet wt/min), intermediate in glucose-perfused hearts (1575 +/- 380) and highest in octanoate-perfused hearts (3074 +/- 499). Thiobarbituric acid reactive substances (TBARS) were unchanged in hearts perfused with pyruvate (16.2 +/- 5 nmoles/g wet wt), but increased significantly in glucose-perfused hearts (36.1 +/- 1) and in octanoate-perfused hearts (45.5 +/- 9). Total glutathione levels were unchanged in hearts perfused with pyruvate (753 +/- 68 nmoles/g wet wt), but significantly decreased in glucose-perfused hearts (594 +/- 68) and in octanoate-perfused hearts (445 +/- 38) following tBHP-treatment. Pyruvate significantly reduced oxidative injury. In contrast, glucose provided a small reduction in injury while octanoate-perfused hearts had the most severe injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Pharmacokinetics of cefpirome in pediatric patients.

Cefpirome is a new investigational cephalosporin. We designed a study to determine the pharmacokinetics and tolerance of cefpirome in pediatric patients. A single dose of cefpirome was administered intravenously over 15 min to 18 patients (age 0.5 to 18 years). The doses were 10 mg/kg of body weight for five patients, 25 mg/kg of body weight for seven patients, and 50 mg/kg of body weight for six patients. Blood samples were collected at 0, 0.25, 0.5, 1, 3, 5, and 8 h after the dose, and cefpirome was measured by a high-performance liquid chromatography method. The maximum concentration in serum ranged from about 53.6 to 454 micrograms/ml after doses of 10 to 50 mg/kg. The total body clearance, apparent volume of distribution, and elimination half-life were 2.15 +/- 0.70 ml/min/kg, 0.32 +/- 0.32 liter/kg, and 1.8 +/- 1.3 h, respectively. No significant adverse effects were attributed to cefpirome. These data may be useful in conducting efficacy and safety studies of cefpirome in pediatric patients.

Adolescent↗
PubMed1994

Effect of Plasmodium berghei infection and antimalarial treatment on heme synthesis in mice.

Plasmodium berghei infection impaired the hepatic heme synthesizing machinery of mice. Key enzymes, viz. S-aminolevulinic acid synthase, S-aminolevulinic acid dehydrase and ferrochelatase were found to be decreased. In contrast, tryptophane pyrrolase noticeably increased during parasitic infection. Oral feeding of chloroquine [16 mg (kg body weight)-1 x 4 days] cleared the parasitaemia from infected mice within 72 h and returned the altered levels of enzymes almost to normal a week after cessation of treatment, the exception being tryptophane pyrrolase, which remained unaffected. Chloroquine treatment did not cause any significant alteration in the above-mentioned enzymes of normal mice.

5-Aminolevulinate Synthetase↗
PubMed1994

Presbytis entellus, a new experimental host for Plasmodium fragile.

The course of blood-induced Plasmodium fragile infection in 3 simian hosts, Macaca radiata (bonnet monkey), Macaca mulatta (rhesus monkey), and Presbytis entellus (Indian langur), was studied. The infection in 8 bonnet monkeys was very mild and nonfatal. In M. mulatta, P. fragile produced acute initial infection followed by anemia and death in 3 of 6 monkeys. The parasite has a relatively high level of virulence for P. entellus, a new experimental host for P. fragile, in which peak parasitemia ranging between 15 and 75% was recorded, and the infection was uniformly fatal. Plasmodium fragile infection in P. entellus can serve as an ideal biological counterpart to human Plasmodium falciparum.

Animals↗
PubMed1993

Effect of the antimalarial agents primaquine and (N'-3-acetyl-4-5-dihydro-2-furanyl)-N4-(6-methoxy-8-quinolinyl)1,4-pent ane-diamine on oxidative stress and antioxidant defences in mice.

The effects of the newly developed antimalarial compound, CDRI 80/53 [(N'-3-acetyl-4-5-dihydro-2-furanyl)-N4-(6-methoxy-8-quinolinyl)1,4- pentane-diamine], and primaquine (PQ) on the antioxidant system of mice were determined at equi-effective antimalarial doses on enzyme systems responsible for protection against oxygen, i.e. hepatic superoxide dismutase and catalase. While PQ significantly inhibited these enzyme activities CDRI 80/53 did not. However, both compound 80/53 and PQ increased the level of superoxide anion and lipid peroxidation. It is concluded that compound 80/53 has less effect on antioxidant defence enzymes than PQ.

Animals↗
PubMed1993

Effect of chloroquine on hepatic heme-oxygenase during Plasmodium berghei infection in mice.

Hepatic heme-oxygenase and heme levels were monitored during Plasmodium berghei infection and chloroquine treatment in Swiss albino mice. A progressive increase in heme-oxygenase and heme levels was noticed with the rise in parasitemia. Further, chloroquine treatment did not result in any change towards normal heme-oxygenase and heme content, when they were assayed a week after cessation of drug treatment. Chloroquine treatment of non-parasitized and parasitized mice resulted in significant loss of the enzyme activity after about 6 weeks.

Animals↗
PubMed1992

Status of oxidative stress and antioxidant defences during Plasmodium knowlesi infection and chloroquine treatment in Macaca mulatta.

Plasmodium knowlesi (a simian malarial parasite) infection resulted in elevation of hepatic oxidative stress in monkeys. Further, the antioxidant defence system of the host was also noticeably affected. The infected monkeys showed a marked increase in the levels of superoxide (O2-), lipid peroxidation (LPO), glutathione (GSH) and xanthine oxidase (XO), and decreased levels of superoxide dismutase (SOD) and catalase. Oral administration of chloroquine (20 mg kg body wt-1 for 3 days) to infected monkeys caused recovery trends in oxidative stress and antioxidant defences to almost normal a week after cessation of drug treatment.

Animals↗
PubMed1992

Alterations in host regulatory glycolytic enzymes during pathogenesis of primate malaria and following chloroquine therapy.

Hexokinase, phosphofructokinase and pyruvate kinase, the regulatory enzymes of the glycolytic sequence, showed progressive increases in their activities with the rise of parasitaemia in Plasmodium knowlesi-infected rhesus monkey serum and red blood cells. Chloroquine therapy cleared the parasitaemia in 72 h and brought the elevated levels of these enzymes back to almost normal in about 30 days.

Animals↗
PubMed1992

Studies on glycolytic enzymes of Plasmodium knowlesi, a simian malaria parasite, and infected host erythrocytes.

Almost all of the important enzymes of glycolytic sequence were studied in isolated schizonts of Plasmodium knowlesi as well as in normal and P. knowlesi parasitized rhesus red blood cells. Significant activities of all the glycolytic enzymes assayed were observed in cell-free schizonts and the levels of all were found to be considerably elevated in infected host erythrocytes, confirming that the consumption of glucose is dramatically increased in host red cells, consequent to malaria infection.

Animals↗
PubMed1992

Lack of interaction between cefpirome and alcohol.

An observer-blind randomized, placebo-controlled, crossover study was conducted in 22 healthy male subjects. They received 2 g cefpirome or placebo intravenously following an overnight fast. One hour later they consumed a single 0.5 g/kg dose of alcohol. The treatments were reversed after a seven-day 'washout' period. Subjects were evaluated for any adverse events or 'disulfiram-like' symptoms. The effects of cefpirome on the pharmacokinetics of alcohol were also studied. There were no statistically significant differences in mean values for the various pharmacokinetic parameters for plasma alcohol between the cefpirome and placebo treatment groups. There were no side effects or 'disulfiram-like' reactions following consumption of alcohol in either group. A single iv dose of 2 g cefpirome was well-tolerated in healthy males and, moreover, pre-treatment with cefpirome did not adversely affect the metabolism of alcohol in these subjects.

Adult↗