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P V Rao

Publications and source records attributed to P V Rao.

At least 19 recordsLinked to original sources
PubMed1999

ELISA for the detection of venoms from four medically important snakes of India.

A double antibody sandwich enzyme linked immunosorbent assay (ELISA) was developed to detect Echis carinatus venom in various organs (brain, heart, lungs, liver, spleen and kidneys) as well as tissue at the site of injection of mice, at various time intervals (1, 6, 12, 18, 24 h and 12 h intervals up to 72 h) after death. The assay could detect E. carinatus venom levels up to 2.5 ng/ml of tissue homogenate and the venom was detected up to 72 h after death. A highly sensitive and species-specific avidin-biotin microtitre ELISA was also developed to detect venoms of four medically important Indian snakes (Bungarus caeruleus, Naja naja, E. carinatus and Daboia russelli russelli) in autopsy specimens of human victims of snake bite. The assay could detect venom levels as low as 100 pg/ml of tissue homogenate. Venoms were detected in brain, heart, lungs, liver, spleen, kidneys, tissue at the bite area and postmortem blood. In all 12 human victim cadavers tested the culprit species were identified. As observed in mice, tissue at the site of bite area showed the highest concentration of venom and the brain showed the least. Moderate amounts of venoms were found in liver, spleen, kidneys, heart and lungs. Development of a simple, rapid and species-specific diagnostic kit based on this ELISA technique useful to clinicians is discussed.

Adolescent↗
PubMed1998

Betaine-homocysteine methyltransferase is a developmentally regulated enzyme crystallin in rhesus monkey lens.

We describe herein the characterization of a major 45-kDa protein from the soluble betaH-crystallin fraction of rhesus monkey (Macaca mulatta) lens. Based on partial peptide sequence, immunoreactivity, and enzymatic activity, this protein has been identified as betaine-homocysteine S-methyltransferase (BHMT: EC 2.1.1.5), an enzyme that catalyzes the methylation of homocysteine using either betaine or thetins as methyl donors. This protein was found to be expressed abundantly in the nuclear region of the monkey lens, reaching approximately 10% of the total nuclear protein, but was barely detectable in the epithelium and cortex regions of the lens. Because the nucleus represents the early embryonic and fetal stages of lens development, we infer that BHMT expression in the lens of the eye is developmentally regulated. By virtue of its high abundance, BHMT can be considered an enzyme crystallin (psi-crystallin). This is the first enzyme crystallin to be found in primate lenses.

Adolescent↗
PubMed1998

Modelling cure rates using the Gompertz model with covariate information.

We extend the modified Gompertz hazard function, first used by Cantor and Shuster for estimation of cure rates from pediatric clinical trials, by including covariate effects. The extended model provides a convenient method for estimation of the cure rate as a function of treatments and covariates.

Algorithms↗
PubMed1998

Mouse hepatitis virus receptor levels influence virus-induced cytopathology.

We developed human (HeLa) cell lines in which mouse hepatitis virus receptor (MHVR) levels could be regulated by addition of tetracycline. We used these cell lines to determine whether MHVR levels impact the degree of cytopathology induced by infection with the lytic MHV A59 strain. Two cultures were studied; HeLa-MHVRlo (less than 3,000 molecules per cell) and HeLa-MHVRhi (300,000 molecules per cell). Both supported synthesis of infective A59 virus. However, the MHVRlo cells showed no virus-induced cytopathology while the MHVRhi cells uniformly died within 14 hours after infection. This cell death was not related to virus-induced syncytium formation as it occurred even in subconfluent cells overlaid with fusion-blocking antiviral antibodies. MHV A59 spike proteins produced by vaccinia vectors also killed the MHVRhi cells within 12 hours postinfection--MHVRlo cells infected in parallel were intact as judged by trypan blue exclusion. Our current hypothesis is that the accumulation of intracellular complexes composed of spike and MHVR proteins leads to acute single cell lysis.

Animals↗
PubMed1998

The risk of nephrectomy during local control in abdominal neuroblastoma.

METHODS: Eight hundred sixty-eight children presenting from 1981 to 1991 were treated on five multiagent chemotherapy protocols by members of the Pediatric Oncology Group for advanced-stage neuroblastoma with large primary tumors crossing the midline or distant metastasis. Of these children, 696 had abdominal (adrenal or paravertebral) primary tumors. One hundred sixteen children underwent greater than 50% surgical resection of these abdominal primary tumors before chemotherapy, and 233 underwent similar surgery after induction chemotherapy. RESULTS: Among the 349 who underwent surgical resection, 52 children (14.9%) had nephrectomy or renal infarction during surgery for local control. There was a 25% incidence among those with initial resection (29 patients) and a 9.9% incidence in the postchemotherapy resections (23 patients). Reasons for nephrectomy given by the surgeons included direct involvement of the kidney by adjacent tumor (17 children), clinical impression that the tumor was a Wilms' tumor (11 children), renal vessels could not be separated from the tumor (10 children), extensive tumor surrounding the kidney (8 children), postoperative renal infarction (4 children), marked decrease in unilateral renal function after chemotherapy (1 child), and position of the tumor posterior to the kidney and vena cava making resection without nephrectomy impossible (1 child). Of the patients undergoing nephrectomy, four children had an upper pole nephrectomy in conjunction with their adrenalectomy and resection of the tumor. Pathological review of the resected tumor available in 47 cases demonstrated direct involvement of the renal parenchyma in 18 cases (38% of the nephrectomies) and in 5.2% of those undergoing resection. In children undergoing initial resection, the risk for nephrectomy (as calculated by the methods described by Gart) was more than twice compared with those undergoing resection after chemotherapy (P = .012; odds ratio, 2.32; 95% confidence interval of 1.23 to 4.42). CONCLUSIONS: This review confirms that renal parenchymal involvement does occur in a significant number of children with abdominal neuroblastoma. It also suggests that preoperative chemotherapy may decrease the number of nephrectomies required to achieve a total or subtotal resection.

Abdominal Neoplasms↗
PubMed1998

Intracellular complexes of viral spike and cellular receptor accumulate during cytopathic murine coronavirus infections.

Murine hepatitis virus (MHV) infections exhibit remarkable variability in cytopathology, ranging from acutely cytolytic to essentially asymptomatic levels. In this report, we assess the role of the MHV receptor (MHVR) in controlling this variable virus-induced cytopathology. We developed human (HeLa) cell lines in which the MHVR was produced in a regulated fashion by placing MHVR cDNA under the control of an inducible promoter. Depending on the extent of induction, MHVR levels ranged from less than approximately 1,500 molecules per cell (designated R(lo)) to approximately 300,000 molecules per cell (designated R(hi)). Throughout this range, the otherwise MHV-resistant HeLa cells were rendered susceptible to infection. However, infection in the R(lo) cells occurred without any overt evidence of cytopathology, while the corresponding R(hi) cells died within 14 h after infection. When the HeLa-MHVR cells were infected with vaccinia virus recombinants encoding MHV spike (S) proteins, the R(hi) cells succumbed within 12 h postinfection; R(lo) cells infected in parallel were intact, as judged by trypan blue exclusion. This acute cytopathology was not due solely to syncytium formation between the cells producing S and MHVR, because fusion-blocking antiviral antibodies did not prevent it. These findings raised the possibility of an intracellular interaction between S and MHVR in the acute cell death. Indeed, we identified intracellular complexes of S and MHVR via coimmunoprecipitation of endoglycosidase H-sensitive forms of the two proteins. We suggest that MHV infections can become acutely cytopathic once these intracellular complexes rise above a critical threshold level.

Animals↗
PubMed1998

Prognostic significance of age, MYCN oncogene amplification, tumor cell ploidy, and histology in 110 infants with stage D(S) neuroblastoma: the pediatric oncology group experience--a pediatric oncology group study.

PURPOSE: Although a high rate of spontaneous regression is observed in infants with stage D(S) neuroblastoma (NB), survival is not uniform. To determine the prognostic relevance of age at diagnosis, therapy, and tumor biology in infants with stage D(S) NB, we reviewed the Pediatric Oncology Group (POG) experience. PATIENTS AND METHODS: A review of patients diagnosed with stage D(S) NB registered on POG protocols was performed. Survival according to age at diagnosis, treatment, and tumor biology was determined. RESULTS: Between 1987 and 1996, 110 infants with stage D(S) NB had an estimated 3-year survival rate of 85% +/- 4%; survival rate was 71% +/- 8% for infants 2 months of age or younger, and 68% +/- 12%, 44% +/- 33%, and 33% +/- 19% for patients with diploid, MYCN-amplified, and unfavorable histology tumors, respectively. Survival rates were similar for patients who received adjuvant chemotherapy versus those who did not (82% +/- 5% v 93% +/- 6%, respectively; P = .187). Furthermore, there was no statistical difference in survival rate for patients who underwent complete resection of their primary tumor compared with those who underwent partial resection or biopsy only (90% +/- 5% v 78% +/- 7%, respectively; P = .083). CONCLUSION: Our review confirmed that the survival of infants with stage D(S) NB is excellent. However, subsets of patients with poor prognosis can be identified by young age and unfavorable biologic factors. More effective therapy is needed for the group of stage D(S) infants who show unfavorable clinical and biologic features.

Age Factors↗
PubMed1997

Guinea pig and bovine zeta-crystallins have distinct functional characteristics highlighting replacements in otherwise similar structures.

zeta-Crystallin, a major cytosolic protein of guinea pig lens, has been characterized as an NADPH:quinone oxidoreductase (EC 1.6.5.5) [Rao et al. (1992) J. Biol. Chem. 267, 97-103]. A bovine lens homolog with 83% sequence identity was found to have very different functional characteristics. While the bovine lens zeta-crystallin exhibits similar physicochemical properties, such as molecular weight, hydropathy profile, and predicted secondary structure, and exhibits strong immunological cross-reactivity with the guinea pig and human lens zeta-crystallins, it shows minimal quinone oxidoreductase activity. On the other hand, bovine lens zeta-crystallin, but not guinea pig zeta-crystallin, showed a strong binding affinity to single-stranded DNA (ssDNA) that could be competed with NADPH, the specific cofactor of zeta-crystallin. NADH and dextran sulfate did not affect this characteristic of bovine zeta-crystallin and the enzyme showed no binding affinity for the heparin-Ultragel A4R. Two-dimensional electrophoresis of bovine lens zeta-crystallin showed a distinct pattern of posttranslational charge modification as compared to the guinea pig protein. Alignment of eight zeta-crystallin sequences, and computer modelling of the bovine and human forms based on the crystallographically analyzed Escherichia coli form, suggest that if loss of a functional residue accounts for the lowered catalytic activity of the bovine protein, Tyr 52 of the E. coli enzyme, and the equivalent Tyr present in all known mammalian forms except the bovine, is the likely candidate. In the bovine form this tyrosine is replaced by histidine.

Amino Acid Sequence↗
PubMed1997

Identification of a contiguous 6-residue determinant in the MHV receptor that controls the level of virion binding to cells.

Murine carcinoembryonic antigens serve as receptors for the binding and entry of the enveloped coronavirus mouse hepatitis virus (MHV) into cells. Numerous receptor isoforms are now known, and each has extensive differences in its amino terminal immunoglobulin-like domain (NTD) to which MHV binds via its protruding spike proteins. Some of these receptor alterations may affect the ability to bind viral spikes. To identify individual residues controlling virus binding differences, we have used plasmid and vaccinia virus vectors to express two forms of MHV receptor differing only in their NTD. The two receptors, designated biliary glycoproteins (Bgp) 1a and 1bNTD, varied by 29 residues in the 107 amino acid NTD. When expressed from cDNAs in receptor-negative HeLa cells, these two Bgp molecules were displayed on cell surfaces to equivalent levels, as both were equally modified by a membrane-impermeant biotinylation reagent. Infectious center assays revealed that the 1a isoform was 10 to 100 times more effective than 1bNTD in its ability to confer sensitivity to MHV (strain A59) infection. Bgp1a was also more effective than Bgp1bNTD in comparative virus absorption assays, binding 6 times-more MHV (strain A59) and 2.5 times more MHV (strain JHMX). Bgp1a was similarly more effective in promoting the capacity of viral spikes to mediate intercellular membrane fusion as judged by quantitation of syncytia following cocultivation of spike and receptor-bearing cells. To identify residues influencing these differences, we inserted varying numbers of 1b residues into the Bgp1a background via restriction fragment exchange and site-directed mutagenesis. Analysis of the resulting chimeric receptors showed that residues 38 to 43 of the NTD were key determinants of the binding and fusion differences between the two receptors. These residues map to an exposed loop (C-C' loop) in a structural model of the closely related human carcinoembryonic antigen.

Amino Acid Sequence↗
PubMed1997

Analysis of small GTP-binding proteins of the lens by GTP overlay assay reveals the presence of unique GTP-binding proteins associated with fiber cells.

Low molecular weight GTP-binding proteins are molecular switches which are thought to play pivotal roles in cell growth, differentiation, cytoskeletal organization and vesicular trafficking. In this study, members of this family of proteins have been identified and characterized in the eye lens, for the first time. [alpha 33P]GTP blot overlay assays of monkey and human lens water soluble and membranous insoluble fractions revealed the presence of specific GTP-binding proteins in the range of 20-30 kDa (small GTPases) in both fractions, with much higher amounts in the membranous insoluble fraction. In the insoluble fraction, in addition to 20-30 kDa GTPases, there are three distinct GTP-binding proteins, ranging from 33-45 kDa. The small GTPases (20-30 kDa) were present throughout the lens in epithelium, cortex and nucleus, while the 33-45 kDa GTP-binding protein bands were exclusively associated with the cortex and nucleus (fiber cells). Analysis of lens fractions by two-dimensional electrophoresis, immunoprecipitation using monoclonal and sequence specific polyclonal antibodies and C3 exoenzyme mediated ADP-ribosylation demonstrated the presence of Ras, Rap, Rho, Rac, Rab and several other small GTPases. The 33-45 kDa GTP-binding proteins that are associated with lens fiber cells appear to be distinct from the small GTPases and from heterotrimeric GTPases, and were not detected in brain or heart tissue. The presence of different complements of GTP-binding proteins in lens fibers and epithelial, cells suggests their involvement in important regulatory functions, possibly related to cell growth, differentiation and organization of the cytoskeleton.

Animals↗
PubMed1997

Event-free survival of children with biologically favourable neuroblastoma based on the degree of initial tumour resection: results from the Pediatric Oncology Group.

We analysed the 2-year event-free survival (EFS) of 49 patients 1 year of age and older, with stage 2B or 3 neuroblastoma, treated on Pediatric Oncology Group protocols 8742 and 9244, with respect to the degree of tumour resection at diagnosis. The 2-year EFS rate for 21 children whose tumours were completely resected at diagnosis was 85% (SE = 10%) compared with an EFS rate of 70% (SE = 9%) for the 28 children whose tumours were incompletely resected at diagnosis. Despite the observed trend in favour of complete resection, these EFS curves were not statistically significantly different (P = 0.259). Patients with favourable Shimada histology tumours had an EFS rate of 92% (SE = 7%) compared with a rate of 58% (SE = 15%) for patients with unfavourable histology tumours. EFS curves for the two histologic groups were significantly different (P = 0.009). The impact of aggressive surgery and adjuvant chemotherapy on the outcome of patients with biologically favourable regional neuroblastoma is still unclear.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Toxicity associated with high-dose cytosine arabinoside and total body irradiation as conditioning for allogeneic bone marrow transplantation.

Seventy-three patients with hematological cancers undergoing allogeneic bone marrow transplantation (BMT) were evaluated for event-free survival (EFS) and toxicity. All received 36 g/m2 cytosine arabinoside (HDA) and 1200 cGy fractionated total body irradiation (TBI). We assessed the association of EFS and toxicities with the following risk factors; age, gender, diagnosis, initial relapse risk and patient-donor histocompatibility. The EFS probability is 33% at 800 days post-BMT. Twenty-six patients (36%) died of toxicity within 100 days and 14 (19%) have relapsed. EFS was inversely associated with age (P < 0.0001) and initial relapse risk (P = 0.007). The risk of pulmonary (P = 0.023) and hepatic toxicity (P = 0.011) increased with age. Diagnosis other than acute lymphoblastic leukemia (ALL) was a risk factor (P = 0.015) for graft-versus-host disease (GVHD); and fewer ALL patients died from toxicity (P = 0.014). The probability of sepsis within 100 days post-BMT correlated (P = 0.007) with initial relapse risk. We conclude: (1) the lower EFS and greater pulmonary and hepatic toxicity associated with increasing age indicate a need for less toxic regimens that maintain high antileukemic efficacy for older patients; (2) the high GVHD and sepsis rates seen in certain categories of patients indicate a need for careful definition of eligibility criteria for this still highly toxic treatment.

Adolescent↗
PubMed1997

Ureteroscopic lithotripsy using mini-endoscope and Swiss lithoclast: experience in 147 cases.

To evaluate the efficacy of a semirigid mini-endoscope and the Swiss Lithoclast compared with a conventional rigid endoscope and ultrasound, the results of transurethral ureteroscopic lithotripsy in 147 patients over a period of 30 months were analyzed according to the type of ureteroscope (rigid v semirigid) and energy (ultrasound v Lithoclast) used. In the initial 25 cases (Group I), a conventional rigid ureteroscope and ultrasound were used. The latter 122 patients (Group II) were subjected to ureteroscopic lithotripsy using a miniscope and the Lithoclast. The results were superior in Group II with respect to the overall success rate (p = 1.6 x 10[-2]), first-attempt success rate (p = 2.9 x 10[-4]), and the need for ureteral dilation (P = 1.0 x 10[-6]) compared with Group I. There were no major complications. Overall, minor complications (hematuria and urinary tract infection) were observed in 25% of the cases. Further, the results of ureteroscopic lithotripsy in Group II were comparable to those of SWL in situ for upper ureteral calculi and better than for those located in the iliac and lower ureter as reported previously. Our results demonstrate that the Swiss Lithoclast provides effective fragmentation of even hard and smooth stones without increasing the complication rate. This lithotripter is reliable, safe, and simple to operate. In addition, the cost of maintenance is almost nil.

Adolescent↗
PubMed1997

Toxicity evaluation of freshwater cyanobacterium Microcystis aeruginosa PCC 7806: II. Nephrotoxicity in rats.

Nephrotoxic potential of laboratory cultures of freshwater cyanobacterium (blue-green alga) Microcystis aeruginosa PCC 7806 (Pasteur Institute) was assessed in male rats. The animals were injected intraperitoneally with 0.5, 1.0 and 2.0 LD50 doses of lyophilized cell extract. Elevated plasma urea and creatinine levels were accompanied by decrease in protein and albumin levels, followed by hematuria, proteinuria and bilirubinuria. Also decrease in kidney lactate dehydrogenase and glutamic oxaloacetic transaminase indicated possible nephrotoxic potential of the cyanobacteria. The extract also produced various hematological changes associated with stagnant type of hypoxia. High performance liquid chromatography of the culture identified the active principle (toxin) as Microcystin-LR.

Alkaline Phosphatase↗
PubMed1997

Role of small GTP-binding proteins in lovastatin-induced cataracts.

PURPOSE: To investigate the biochemical mechanisms involved in the cataract induced by lovastatin, a commonly used cholesterol-lowering agent. METHODS: The effects of lovastatin on lens transparency and on lens epithelial cell proliferation and structure have been investigated using organ-cultured rat lenses and cultured epithelial cells from human and rabbit lenses, respectively. Lens histologic and morphologic changes were recorded microscopically. Small GTP-binding protein profiles were determined by [alpha-32P] GTP overlay assays. RESULTS: Rat lenses organ cultured for 7 days with lovastatin, a 3-hydroxy-3-methylglutaryl CoA reductase inhibitor, developed frank subcapsular opacity. Lens epithelial cells (both human and rabbit) demonstrated extensive morphologic changes and inhibition of proliferation when treated with lovastatin. Histologic sections of lovastatin-treated lenses showed partial to complete degeneration of the central epithelium, distortion of elongating epithelial cells, and extensive vacuole formation in the equatorial regions of the cortex. Supplementation of the medium with DL-mevalonic acid (a precursor of isoprenoids whose synthesis is inhibited by lovastatin) prevented the lovastatin-induced changes in whole lenses or in lens epithelial cell cultures, whereas supplementation with cholesterol had no such effect. GTP-binding proteins accumulated in the soluble fractions of lovastatin-treated lens epithelial cells. This was consistent with a blockade in isoprenylation preventing normal association with membranes. CONCLUSIONS: The findings suggest that impairment of the function of small GTP-binding proteins, due to a lovastatin-induced blockade in their isoprenylation, affects lens cell structure and proliferation in tissue culture and induces lens opacity in organ culture. These findings are consistent with the proposed roles of small GTP-binding proteins as molecular switches that regulate fundamental cellular processes, including growth, differentiation, and maintenance of cell structure.

Animals↗
PubMed1997

Diet and lifestyle guidelines and desirable levels of risk factors for the prevention of diabetes and its vascular complications in Indians: a scientific statement of The International College of Nutrition. Indian Consensus Group for the Prevention of Diabetes.

BACKGROUND: There has been a rapid increase in the prevalence of diabetes and cardiovascular disease in India, in association with rapid changes in diet and lifestyle. In adults, the prevalence of diabetes, hypertension and coronary artery disease is two- to threefold greater in the urban population than in rural populations; it is associated with modest insulin resistance in urban groups. METHODS: In response to a proposal by the International College of Nutrition that specialist experts should develop consensus recommendations for the prevention of chronic diseases, Indian specialists in diabetes and vascular disease have collaborated to produce guidelines relevant to the population of India. RECOMMENDATIONS: Because Indian urban populations have a modest increase in overweight and low rates of obesity in association with the rapid emergence of diabetes and cardiovascular risk, a body mass index of 21 kg/m2 should be considered safe, with a range of 19-23 kg/m2 acceptable; > 23 kg/m2 should be considered overweight, and > 25 kg/m2 should be taken to indicate obesity. A waist:hip ratio > 0.88 in males and > 0.85 in females should be considered to indicate central obesity, because the prevalence of coronary disease, hypertension and associated disturbances of insulin resistance are more common above these limits. For the prevention of vascular disease, there is general international consensus that the desirable serum concentration of cholesterol should be < 170 mg/dl (> 4.42 mmol/l), which may also be optimal for Indians; values between 170 and 200 mg/dl (4.42-5.2 mmol/l) should be considered borderline. The critical values for low density lipoprotein cholesterol may be < 90 mg/dl (ideal), 90-110 mg/dl (borderline high) and > 110 mg/dl (high) (< 2.32, 2.32-2.84 and > 2.84 mmol/l, respectively). Fasting triglycerides should be < 150 mg/dl (< 1.69 mmol/l) and high-density lipoprotein cholesterol > 35 mg/dl (> 0.9 mmol/l). The limit for the total energy derived from fat intake should be < 21%/day (7% each for saturated, polyunsaturated and mono-unsaturated fatty acids). The carbohydrate intake should provide more than 65% of daily energy, mainly from complex carbohydrates. A daily dietary intake of 400 g fruits, vegetables and legumes, 400 g cereals, in conjunction with 25 g soya bean or mustard or canola oils (rich in n-3 fatty acids) in place of fats rich in saturated fat, may be protective against diabetes and vascular disease. Moderate physical activity with the aim of burning 300 Kcal/day (> 1255 KJ/day), and cessation of tobacco and alcohol consumption, may provide an effective programme for prevention of diabetes and its vascular complications in Indians.

Adult↗
PubMed1996

The cyanobacterial toxin microcystin-LR induced DNA damage in mouse liver in vivo.

Microcystin-LR (MCLR) is a potent cyclic heptapeptidic hepatotoxin produced by the cyanobacterium Microcystis aeruginosa. Hepatotoxic and other toxic manifestations of MCLR are well documented. However, information on genotoxicity of MCLR is limited. The present investigation addresses the DNA damage induced by MCLR in mouse liver in vivo. The DNA strand breaks were measured by the fluorimetric analysis of DNA unwinding (FADU). MCLR at 0.5, 1.0 and 2.0 LD50 doses exhibited a dose and time-dependent DNA damage accompanied by similar effects on various enzymes of hepatic origin, e.g. lactate dehydrogenase, alkaline phosphatase and gamma glutamyl transferase. MCLR-induced genomic DNA fragmentation was also assessed qualitatively by agarose gel electrophoresis. MCLR induced random DNA fragmentation and DNA degradation. Glutathione (GSH) pretreatment significantly extended the survival time of animals exposed to 1.0 LD50 MCLR but offered only partial protection with regard to DNA damage. The DNA damage observed in the present study can be ascribed to activation of endonucleases.

Animals↗