Complement-mediated bacterial killing assays.
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Biomedical subjects
Publications and source records attributed to S Gulati.
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The steroid response pattern to standard prednisolone therapy is of immense diagnostic, therapeutic and prognostic value for the treating physician in managing children with nephrotic syndrome. None of the studies from our country has analysed the clinical, biochemical and histopathological profile in different steroid response categories. To address this problem we conducted a study comprising 127 children with nephrotic syndrome referred to our institute. They were treated with oral prednisolone according to the APN protocol. Based on the subsequent response these children were classified into different steroid response categories on follow-up. Of the 116 children with follow-up of more than six months, infrequent relapsers constituted the majority (37.9%). The frequency of other steroid response categories was as follows: frequent relapsers (21.6%), steroid-dependent (18.1%), initial non-responders (17.3%) and subsequent non-responders (5.1%). The factors predicting a poor response to standard prednisolone therapy in our study were age of onset more than eight years, male sex, hypertension, microscopic haematuria and presence of non-minimal change nephrotic syndrome lesions on histopathology.
Randomized phase III clinical trials provide important information on the efficacy of new pharmaceutical agents for cancer patients. Policy makers are showing increased interest in both economic and clinical data on new agents in order to approve pharmaceuticals for widespread use, and clinical trials have been viewed as the proper setting to evaluate these outcomes for new agents. With the recent approval of new pharmaceutical agents that have high costs, early assessments of economic benefit have taken on larger importance to physicians and patients. The integration of economic and clinical analysis in phase III clinical trials raises methodological and practical issues related to study design, collection of data on resource utilization, and generalizability of data to other settings. In this paper, we review these issues and discuss their relationship to clinical trials for new pharmaceutical products.
In a series of clinical studies at Memorial Sloan-Kettering Cancer Center, we have used hematopoietic growth factors and peripheral blood-derived hematopoietic progenitor cells to facilitate delivery of multiple courses of high-dose chemotherapy at abbreviated treatment intervals. In these studies, we have demonstrated the feasibility of cross-over regimens involving induction chemotherapy with high-dose cyclophosphamide, supported by granulocyte colony-stimulating factor and followed by multiple peripheral blood leukapheresis to harvest progenitor cells. These cells are then used as rescue for the consolidation component of treatment, which, in the earlier-generation studies, consisted of a single course of high-dose carboplatin/etoposide/cyclophosphamide chemotherapy. In subsequent studies, patients received either four courses of high-dose carboplatin or carboplatin/cyclophosphamide or tandem courses of thiotepa. In all cases, the planned interval between treatments was 14 days, and the achieved median was approximately 16 days. These studies show that the administration of high-intensity regimens that deliver multiple courses of very high-dose chemotherapy at relatively brief intervals is feasible. Our current research focuses on exploiting these findings to devise disease-specific regimens for breast and ovarian cancer.
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There are well defined therapeutic protocols for childhood nephrotic syndrome. Appropriate therapy helps in minimizing side effects besides decreasing referrals to tertiary care centres. We have analysed the appropriateness of therapy of primary care physicians in 111 children with nephrotic syndrome referred to our Institute from January 1989 to December 1991. Prednisone was administered in adequate doses in 51 (52.6%), and for adequate duration in 41 children (42.2%). Adjunctive cyclophosphamide therapy was administered in the recommended doses and duration in 33% of the cases. On evaluation of the therapy it was observed that inappropriate treatment had been administered by 39.4% of the pediatricians, 59% of internists and 80% of general practitioners. This study highlights the lacunae in the current state of knowledge amongst the primary physicians and highlights the need for creating greater awareness regarding the therapy of children with nephrotic syndrome.
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Fifty two children (upto 12 years age) with acute renal failure (ARF) admitted to the Nephrology services between January, 1989 to August, 1992 were studied to determine the cause and outcome. Of these, 39 were boys and 13 girls; 27 (51.9%) patients were below 4 years of age. Hemolytic uremic syndrome (HUS) was the commonest cause of ARF (30.8%) followed by acute tubular necrosis (ATN) in 28.84% and acute glomerulonephritis in 19.23%. All patients had severe renal involvement with anuria in 53.6% and oliguria in 46.4% at presentation. HUS was the leading cause of anuria (53.6%), followed by obstructive uropathy (21.4%). Thirty five patients required dialytic support for a median duration of 18 days (2-90 days). The mortality was 34.6%. Seven patients of HUS, 4 patients of ARF following surgery, 3 patients each of ATN and glomerulonephritis and one patient of obstructive uropathy died. Anuria at onset, central nervous system or respiratory complications and delay in institution of dialytic support were bad prognostic factors. We conclude that early referral and prompt institution of dialytic support may be helpful in decreasing the mortality.
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cDNA clones encoding the major subunit of the Duffy blood group were isolated from a human bone marrow cDNA library using a PCR-amplified DNA fragment encoding an internal peptide sequence of glycoprotein D (gpD) protein. The open reading frame of the 1267-bp cDNA clone indicated that gpD protein was composed of 338 amino acids, predicting a M(r) of 35,733, which was the same as a deglycosylated gpD protein. Portions of the predicted amino acid sequence, matched with six CNBr/pepsin peptides obtained from affinity-purified gpD protein. In ELISA analysis, an anti-Duffy murine monoclonal antibody reacted with a synthetic peptide deduced from the cDNA clone. Hydropathy analysis suggested the presence of 9 membrane-spanning alpha-helices. In bone marrow RNA blot analysis, the gpD cDNA detected a 1.27-kb mRNA in Duffy-positive but not in Duffy-negative individuals. It also identified the same size mRNA in adult kidney, adult spleen, and fetal liver; in brain, it detected a prominent 8.5-kb and a minor 2.2-kb mRNA. In Southern blot analysis, gpD cDNA identified a single gene in Duffy-positive and -negative individuals. Duffy-negative individuals, therefore, have the gpD gene, but it is not expressed in bone marrow. The same or a similar gene is active in adult kidney, adult spleen, and fetal liver of Duffy-positive individuals. Whether this is true in Duffy-negative individuals remains to be demonstrated. A GenBank sequence search yielded a significant protein sequence homology to human and rabbit interleukin-8 receptors.
We have previously demonstrated that ischemic injury results in the loss of peroxisomal functions (e.g., inhibition of catalase activity and fatty-acid beta-oxidation activity). To understand the molecular mechanism leading to the loss of peroxisomal beta-oxidation in ischemic tissue, we examined the levels of individual enzyme activities and proteins of the peroxisomal beta-oxidation system and overall fatty-acid oxidation in peroxisomes isolated from kidney exposed to ischemia-reperfusion injury. The peroxisomal beta-oxidation decreased with an increase in time of ischemic injury (53% and 43% of the control in kidneys exposed to 60 and 90 min ischemia, respectively). In vivo inactivation of catalase with aminotriazole and exposure of isolated peroxisomes to H2O2 resulted in inhibition of peroxisomal beta-oxidation system suggesting that this enzyme system is labile to excessive H2O2 produced during ischemic injury. The enzyme activities of lignoceroyl-CoA ligase, acyl-CoA oxidase, bifunctional enzymes and acyl-CoA thiolase (individual peroxisomal beta-oxidation enzymes) after 90 min of ischemia were 87, 80, 87 and 85% of the control, respectively. This decrease in enzyme activities was more pronounced following reperfusion (28, 11, 23 and 35% of the control, respectively). Immunoblot analysis of these enzymes indicated that the major loss of these enzyme activities during ischemia was due to their inactivation, whereas during reperfusion, proteolysis also contributed toward the observed loss of these activities. In summary, these results demonstrated that loss of peroxisomal beta-oxidation in ischemia-reperfusion injury was due to inactivation and proteolysis of beta-oxidation enzymes. Acyl-CoA oxidase was more sensitive to ischemia-reperfusion injury compared to other enzymes, and the overall loss of peroxisomal beta-oxidation may be a reflection of the loss of acyl-CoA oxidase activity, a rate-limiting enzyme.
The effect of ischemia-reperfusion on activity, protein and m-RNA levels of catalase, copper-zinc and manganese containing superoxide dismutases and glutathione peroxidase, the enzymes that are involved in free radical detoxification was studied in rat kidney. Ischemia alone did not alter either the activities or protein levels of superoxide dismutase and glutathione peroxidase. However, catalase activity was found to be inhibited to 82% of control. The inhibition of catalase was due to the inactivation of the enzyme as there was no significant change in enzyme protein level. Reperfusion following ischemia, however, led to a significant decrease in both the activities as well as the protein levels of all the antioxidant enzymes. The observed overall decrease in total superoxide dismutase activity was the net effect of a decrease in copper-zinc superoxide dismutase while manganese superoxide dismutase activity was found to be increased following reperfusion. This observed increase manganese superoxide dismutase activity was the result of its increased protein level. The mRNA levels for catalase, superoxide dismutases, and glutathione peroxidase were observed to be increased (100-145% of controls) following ischemia; reperfusion of ischemic kidneys, however, resulted in a significant decrease in the levels of mRNAs coding for all the enzymes except manganese superoxide dismutase which remained high. These results suggest that in tissue, the down regulation of the antioxidant enzyme system could be responsible for the pathophysiology of ischemia-reperfusion injury.
Patients with cancer can now benefit from intensive drug dosage. Intensive drug dosage has become more effective because of the availability of better anti-emetics, hematopoietic growth factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte CSF (G-CSF), erythropoietin, etc. and improvements in hematopoietic stem cell transplantation. We have evaluated the clinical and cost effectiveness of GM-CSF in patients undergoing autologous bone marrow transplantation (AuBMT) for Hodgkin's disease. Administration of GM-CSF after AuBMT enhances myeloid and platelet recovery and is cost effective in the treatment of patients with relapsed Hodgkin's disease who received intensive chemotherapy and AuBMT. We also describe the use of various new therapeutic approaches with emphasis on clinical and cost benefit. Further work is needed to improve the route and duration of growth factor(s) infusion and the timing of the various treatments.
Allogeneic bone marrow transplantation (BMT) is a useful approach for treating patients with chronic myelogenous leukemia (CML). In patients who lack a suitable donor, various approaches to utilize the patient's own hematopoietic stem cells obtained from bone marrow and/or peripheral blood have been developed. Preferential recovery of normal human hematopoietic progenitors over CML clone in long-term bone marrow culture (LTBMC) has been observed for a long time. LTBMC initiated in tissue culture (TC) flasks to that in "Lifecell" bags, which are gas-permeable plastic bags in which feeder-layer cells cannot adhere, has been investigated for several years. In our laboratory, cells were incubated in the presence of various growth factors to develop improved methods for stem cell expansion. Sustained hematopoietic stem cell growth in the absence of a feeder layer in plastic gas-permeable bags has been observed. Growth of marrow from patients with CML is being investigated extensively. Combining effective drugs to decrease the Philadelphia (Ph) clone prior to bone marrow harvest and the use of cultured bone marrow may provide a useful method for treating patients with CML. Results of various international studies are also discussed below.
Use of growth factors to augment hematopoietic recovery after cytotoxic therapy is a useful method for dose intensification. We wanted to evaluate the clinical and cost-effectiveness of granulocyte-macrophage colony stimulating factor (GM-CSF; Leucomax) in patients undergoing autologous bone marrow transplantation (ABMT) for Hodgkin's disease. Twenty-four patients with Hodgkin's disease were treated with high-dose chemotherapy and ABMT. Patients were then randomized in a double-blind manner to receive GM-CSF intravenously (10 micrograms/kg) over 6 h or placebo until the absolute neutrophil count (ANC) was greater than 1000/mm3 for 3 days. The study medication was stopped after 30 days. Patients treated with GM-CSF (n = 12) had shorter periods of neutropenia (median duration of an ANC of less than 1000 cells/mm3, 16 versus 27 days on placebo; p = 0.23), shorter periods of platelet-transfusion dependency (median duration, 13.5 versus 21 days on placebo; p = 0.03), shorter hospitalizations (median hospital stay, 32 versus 40.5 days on placebo; p = 0.0004). Other clinical outcomes, such as frequency and severity of toxicities, development of pneumonia or infection, in-hospital death, and response rate were similar in the two groups. Actuarial long-term disease free survival was 58% for patients treated with GM-CSF and 50% for patients who received placebo after 38 months of follow up (p = 0.6).(ABSTRACT TRUNCATED AT 250 WORDS)
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Exogenously supplied catalase, a peroxisomal enzyme, has been found to be of therapeutic value in ischemic injury. Therefore, we examined the effect of ischemic-reperfusion injury on the structure and function of kidney peroxisomes. Ischemic injury changed the density of peroxisomes from 1.21 g/cm3 (peak I) to a lighter density of 1.14 g/cm3 (peak II). The number of peroxisomes moving from the normal density population (peak I) to a lower density population (peak II) increased with an increase in ischemic injury. Latency experiments indicated both populations of peroxisomes to be of intact peroxisomes. Immunoblot analysis with antibodies against peroxisomal matrix and membrane proteins demonstrated that after 90 min of ischemia a significant number of matrix proteins were lost in the peak II population, suggesting that functions of these peroxisomes may be severally affected. Reperfusion following ischemic injury resulted in loss of peroxisomal matrix proteins in both peaks I and II, suggesting that peroxisomal functions may be drastically compromised. This change in peroxisomal functions is reflected by a significant decrease in peroxisomal catalase activity (35%) and beta-oxidation of lignoceric acid (43%) observed following 90 min of ischemia. The decrease in catalase activity was more pronounced in reperfused kidneys even after a shorter term of ischemic injury. Reperfusion restored the normal peroxisomal beta-oxidation in kidneys exposed up to 60 min of ischemia. However, 90 min of ischemia was irreversible as there was a further decrease in beta-oxidation upon reperfusion. The decrease in catalase activity during ischemia alone was due to the formation of an inactive complex, whereas during reperfusion, following 90 min of ischemia, inactivation and proteolysis or decreased synthesis of catalase contributed equally toward the injury. The observed changes in the structure and function of peroxisomes as a result of ischemic-reperfusion injury and the ubiquitous distribution of peroxisomes underlines the importance of this organelle in the pathophysiology of vascular injury in general.