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Biomedical subjects

Ramesh Chandra

Publications and source records attributed to Ramesh Chandra.

At least 37 records · Page 2Linked to original sources
PubMed2005

Protein kinase I of Mycobacterium tuberculosis: cellular localization and expression during infection of macrophage-like cells.

Protein kinase I of Mycobacterium tuberculosis, which has an unusual amino acid composition in its catalytic loop, displayed autophosphorylation and transphosphorylation activity. Immunoblot analysis of sub-cellular fractions of M. tuberculosis, using anti-PknI antibodies raised in rabbits, showed that PknI localizes to the bacterial cytosol. In contrast, PknA was membrane-bound. Relative expression of pknI, when measured by combining molecular beacons and RT-PCR, decreased during infection of THP-1 human macrophages. Expression of pknA and pknB was upregulated during infection. Thus PknI represents a group of protein kinases that is distinct from the more extensively studied enzymes PknA and PknB.

Animals↗
PubMed2005

Synthesis and antibacterial activity of substituted 1,2,3,4-tetrahydropyrazino [1,2-a] indoles.

A series of substituted 1,2,3,4-tetrahydropyrazino [1,2-a] indole derivatives have been synthesized and tested against the Gram positive and Gram negative strains of bacteria namely Staphylococcus aureus (MTCCB 737), Salmonella typhi (MTCCB 733), Pseudomonas aeruginosa (MTCCB 741), Streptomyces thermonitrificans (MTCCB 1824) and Escherichia coli (MTCCB 1652). All synthesized compounds showed mild to moderate activity. However, compounds 4d-f were found to have potent activity against pathogenic bacteria used in the study. Their MIC ranged from 3.75 to 60 microg/disc. In vitro toxicity tests demonstrated that toxicity of 4d-f was not significantly different than that of gentamycin. However, at higher concentration (1000-4000 microg/ml) difference was highly significant.

Anti-Bacterial Agents↗
PubMed2005

4-hydroxyisoleucine an unusual amino acid as antidyslipidemic and antihyperglycemic agent.

Trigonella foenum-graecum, commonly known as fenugreek, is an annual herbaceous plant. From the seeds of T. foenum-graecum an unusual amino acid, 4-hydroxyisoleucine 5, has been isolated, which significantly decreased the plasma triglyceride levels by 33% (P<0.002), total cholesterol (TC) by 22% (P<0.02), and free fatty acids by 14%, accompanied by an increase in HDL-C/TC ratio by 39% in the dyslipidemic hamster model.

Administration, Oral↗
PubMed2005

Nutritional and hypoglycemic effect of fruit pulp of Annona squamosa in normal healthy and alloxan-induced diabetic rabbits.

The nutritive value of the pulp of the edible fruit of Annona squamosa and its effect on various biochemical parameters has been assessed in normal and alloxan-induced diabetic rats. Different doses (2.5, 5.0, 10.0 g/kg b.w.) of fresh fruit pulp of A. squamosa were given to the three groups each of normal healthy and diabetic rabbits orally daily for 1 month. There was a control group of normal as well as diabetic animals which did not receive fruit pulp. Protein efficiency ratio (PER), digestibility coefficient (DC), biological value (BV) and net protein utilization (NPU) were calculated and improvement in the nutritional level was studied by comparing with the control group. Effect of the fruit pulp was also studied on various biochemical parameters, namely fasting blood glucose (FBG), total cholesterol (TCH), HDL-cholesterol, triglyceride (TG), total protein (TPR), alkaline phosphatase (ALKP), serum glutamate oxaloacetate and pyruvate transaminases (SGOT and SGPT), serum creatinine (CRTN) and serum bilirubin (BIL). Protein and glucose in urine were also estimated. Total hemoglobin and glycohemoglobin (HbAc) were estimated in blood before and after 1 month of feeding fruit pulp. Fruit pulp increased the net protein utilization by 29.3 in normal healthy rabbits with 10 g/kg b.w. and 34.1 in induced diabetic (induced by alloxan) animals with 5 g/kg b.w. of the fruit pulp feeding when compared with the control group of rabbits (p < 0.001). Feeding fruit pulp with the same amount increased the total hemoglobin content by 21.0% in normal rabbits and 10.8% in diabetic rabbits. Fruit pulp also reduced the total cholesterol level by 45-46% in normal and 32.4% in diabetic animals with increased HDL-cholesterol. Feeding pulp improved the liver function in normal as well as diabetic rabbit as shown by reduction in the serum SGOT, SGPT, ALKP and bilirubin levels. The optimal improvement in nutritive value of normal animals was found with 5.0-10.0 g/kg b.w. of the fruit pulp feeding, while in diabetic animals it was 2.5-5.0 g/kg b.w. In the diabetic animals pulp feeding between 2.5 and 5.0 g/kg b.w. showed improvement in the glucose tolerance. Further, 5 g/kg b.w. of fruit pulp brought down urine sugar, urine protein and glycohemoglobin in diabetic rabbits. Feeding pulp had increased utilization of dietary protein, body weight as well as the ratio of gain in body weight per gram of protein consumed. It had a protective effect on liver and heart as indicated by reduction in the SGOT, SGPT, ALKP and serum bilirubin levels.

Administration, Oral↗
PubMed2005

Structural conservation of residues in BH1 and BH2 domains of Bcl-2 family proteins.

The sequence of Bcl-2 homology domains, BH1 and BH2, is known to be conserved among anti- and pro-apoptotic members of Bcl-2 family proteins. But structural conservation of these domains with respect to functionally active residues playing role in heterodimerization-mediated regulation of apoptosis has never been elucidated. Here, we have suggested the formation of an active site by structurally conserved residues in BH1 (glycine, arginine) and BH2 (tryptophan) domains of Bcl-2 family members, which also accounts for the functional effect of known mutations in BH1 (G145A, G145E) and BH2 (W188A) domains of Bcl-2.

Amino Acid Sequence↗
PubMed2005

Synthesis and pharmacological evaluation of substituted 5-[4-[2-(6,7-dimethyl-1,2,3,4-tetrahydro-2-oxo-4-quinoxalinyl)ethoxy]phenyl]methylene]thiazolidine-2,4-dione derivatives as potent euglycemic and hypolipidemic agents.

A series of substituted 5-[4-[2-(6,7-dimethyl-1,2,3,4-tetrahydro-2-oxo-4-quinoxalinyl)ethoxy]phenyl]methylene]thiazolidine-2,4-diones were synthesized and their euglycemic and hypolipidemic activities were investigated in Wistar male rats. Based on the in vivo data in rats, compound 4a was identified as a potent euglycemic and hypolipidemic agent.

Animals↗
PubMed2005

EM012, a microtubule-interfering agent, inhibits the progression of multidrug-resistant human ovarian cancer both in cultured cells and in athymic nude mice.

Drug resistance, in particular multidrug resistance, is a serious problem that impedes the effectiveness of chemotherapy. Multidrug resistance results mainly from an enhanced efflux of drugs by drug pumps located on the cell membrane such as P-glycoprotein. In the study reported here we showed that EM012, a microtubule-interfering agent, is a weak substrate for P-glycoprotein and inhibited the proliferation of A2780/ADR human ovarian cancer cells, which possess multidrug resistance due to P-glycoprotein overexpression. A2780/ADR cells treated with EM012 exhibited pronounced mitotic arrest, developed large multilobed nuclei, and eventually died through the initiation of apoptosis. Intraperitoneal treatment of A2780/ADR xenograft tumors in athymic nude mice with EM012 significantly inhibited tumor progression through triggering apoptosis and conferred an apparent survival advantage. Furthermore, EM012 treatment did not cause detectable toxicity to normal tissues. These findings suggest that EM012 may serve as a novel chemotherapeutic agent for the treatment of multidrug-resistant human ovarian cancer.

Animals↗
PubMed2005

Evaluation of antipyretic activity of Calotropis gigantea (Asclepiadaceae) in experimental animals.

The roots of Calotropis gigantea have been used in leprosy, eczema, syphilis, elephantiasis, ulceration and cough in the Indian system of traditional medicine. The present communication evaluated its antipyretic activity by using yeast-induced and TAB (Typhoid) vaccine-induced pyrexia in rats and rabbits. In both yeast-induced and TAB vaccine-induced fever, the fever was significantly reduced and the body temperature was normalized by administration of 200 and 400 mg/kg dose intraperitoneally. Based on the results of the present study it can be concluded that the extract of C. gigantea has potential antipyretic activity against both yeast-induced and TAB vaccine-induced fever, indicating the possibility of developing C. gigantea as a cheaper and potent antipyretic agent.

Analgesics, Non-Narcotic↗
PubMed2005

Targeted activation of transcription in vivo through hairpin-triplex forming oligonucleotide in Saccharomyces cerevisiae.

Triplex forming oligonucleotides (TFO) are known to be potential agents for modifying gene function. In most instances they are utilized for repression of transcription. However hybrid molecules containing cis-acting elements in a duplex DNA in a hairpin form contiguously with the TFO can bind transcription factors in vitro. In the present manuscript we demonstrate that hairpin-TFO can be employed in vivo for targeted activation of gene expression of two genes mapping on chromosome XI of Saccharomyces cerevisiae. The cis-acting GAL4 protein-binding site contained in the hairpin-TFO is targeted in vivo to the 5' upstream sequence of STE6 and CBT1 genes that are transcribed in opposite directions and share a poly(pu/py) sequence that can form triple helical structure. The hairpin-TFO is targeted to this site and promotes the activation of both the genes. These results demonstrate four important aspects relating to activation of gene expression: (i) accessibility of duplex DNA packaged into chromatin to triplex forming sequences in vivo, (ii) the potential use of hairpin-TFO in therapeutics by activation of transcription in vivo, (iii) Sharing of transcription factors between two genes transcribed in opposite directions and (iv) specific activation of genes even when their cognate site is not covalently linked to the gene being activated.

Base Sequence↗
PubMed2005

Ameliorating effect of phytoestrogens on CCl4-induced oxidative stress in the livers of male Wistar rats.

Glutathione-S-transferases and glutathione play a key role in the detoxification of most toxic agents. In the present study, the protective effects, if any, of isoflavone phytoestrogens--genistein and daidzein on the carbon tetrachloride (CCl4) induced changes in the activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutathione S transferase (GSH) and levels of glutathione (GSH) and thiobarbituric acid reactive substances (TBARS)-were studied. The activities of ALT and AST were assayed in the serum, whereas the activity of GST and levels of GSH and TBARS were determined in the livers of rats. The current study involved the division of animals into two main groups: (i) rats pretreated with genistein and daidzein for three days; and (ii) non-pretreated rats. In the pretreated group, rats received oral doses of genistein (7.9 micromol/kg body weight) and daidzein (7.9 micromol/kg body weight) for three consecutive days (once daily) followed by oral dose of CCl4 on the 4th and the 5th day concurrently with the phytoestrogens-genistein or daidzein. In the non-pretreated group animals received oral dose of CCl4 (1 ml/kg body weight) for two consecutive days along with the phytoestrogens-genistein or daidzein. Treatment of male rats with CCl4 significantly elevated the activity of ALT and AST in serum and levels of TBARS in the liver. On the other hand, CCl4 resulted in decreased activity of GST and lowered the GSH levels. Coadministration of genistein and daidzein with CCl4 could not restore the alterations in the activity of ALT and AST caused by CCl4 to normal control levels. However, repeated dose treatments with genistein and daidzein for three days prior to the administration of CCl4 restored such alterations to normal levels. Our results indicate that genistein is more effective than daidzein in counteracting the inhibition of GST activity caused by CCl4 and restoring it to normal levels. Genistein was also more effective than daidzein restoring the induced TBARS levels caused by CCl4 to normal control levels when rats were pretreated with the isoflavone orally for three days. It has been observed that the tested isoflavonoids were able to antagonize the toxic effects of CCl4. Such counteracting effects were more pronounced for genistein and when the phytoestrogens were administered as repeated doses prior CCl4 administration.

Animals↗
PubMed2005

The use of riboflavin and metalloporphyrins in cytochrome P-450 content in Wistar rats.

Phototherapy is commonly used for the treatment of neonatal jaundice. Riboflavin is a photosensitizer that generates singlet oxygen, which promotes bilirubin photodecomposition. Metalloporphyrins are also effective photosensitizers. The effect of a combined dosing regimen of riboflavin and metalloporphyrins was studied, with the aim of increasing the efficiency of the phototherapeutic treatment of hyperbilirubinemia. It was envisaged that riboflavin and the metalloporphyrins, by promoting the photodecomposition of bilirubin, would thereby lead to a reduction of the toxic side effects associated with phototherapy. The results shows that a phototherapeutic treatment, in which riboflavin and metalloporphyrins were co-administered, was effective in reducing Heme Oxygenase activity. However, a comprehensive study of the possible side effects of metalloporphyrin treatment in the wavelength under consideration is essential prior to utilizing these compounds for any clinical applications.

Animals↗
PubMed2005

Stem cell fate specification: role of master regulatory switch transcription factor PU.1 in differential hematopoiesis.

PU.1 is a versatile hematopoietic cell-specific ETS-family transcriptional regulator required for the development of both the inborn and the adaptive immunity, owing to its potential ability to regulate the expression of multiple genes specific for different lineages during normal hematopoiesis. It functions in a cell-autonomous manner to control the proliferation and differentiation, predominantly of lymphomyeloid progenitors, by binding to the promoters of many myeloid genes including the macrophage colony-stimulating factor (M-CSF) receptor, granulocyte-macrophage (GM)-CSF receptor alpha, and CD11b. In B cells, it regulates the immunoglobulin lambda 2-4 and kappa 3' enhancers, and J chain promoters. Besides lineage development, PU.1 also directs homing and long-term engraftment of hematopoietic progenitors to the bone marrow. PU.1 gene disruption causes a cell-intrinsic defect in hematopoietic progenitor cells, recognized by an aberrant myeloid and B lymphoid development. It also immortalizes erythroblasts when overexpressed in many cell lines. Although a number of reviews have been published on its functional significance, in the following review we attempted to consolidate information about the differential participation and role of transcription factor PU.1 at various stages of hematopoietic development beginning from stem cell proliferation, lineage commitment and terminal differentiation into distinct blood cell types, and leukemogenesis.

Animals↗
PubMed2005

Three-dimensional structure prediction of the interaction of CD34 with the SH3 domain of Crk-L.

The monomeric 115-kDa surface protein CD34, which is present on many stem cell populations, has been useful to enumerate the quality and viability of cell suspensions for engraftment. Although these studies assure the validity of CD34 as a stem cell marker, the functional role of this molecule has not been defined. CD34 has been demonstrated to regulate adhesion, differentiation, and proliferation of hematopoietic stem cells and other progenitors. The cytoplasmic domain of CD34 is known to be essential for its function. However, it is not clear how this domain's interactions with other molecules support the functional activity of CD34. Here we show that the cytoplasmic tail of CD34 is structurally similar to the carboxyl terminus of the gap junction protein Connexin 43 (Cx43). Because the activity of CD34 is mediated through its interaction with an SH3 domain of an intracellular protein, we attempted to define the SH3 binding region and amino acids involved in this interaction. We identified Glu325 to Ser334 as potential SH3 binding sites. Our results suggest that the interaction of the cytoplasmic tail of CD34 with the shallow proline-rich motif-binding groove of Crk-L is essential for the function of CD34 in stem cell development.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Glycolipids of Mycobacterium tuberculosis strain H37Rv are potential serological markers for diagnosis of active tuberculosis.

A simple and cost-effective diagnostic tool (TB Screen Test) for the screening of patients with pulmonary and extrapulmonary tuberculosis and for differentiation of those individuals from individuals without tuberculosis, other common infections, and healthy controls has been developed. The serological responses of purified mycobacterial glycolipid antigens were examined by a liposome agglutination assay. The assay was able to detect very low antiglycolipid antibody concentrations in the infected individuals. The sera from the tuberculosis patient group had significantly higher concentrations of antiglycolipid antibody than the sera from uninfected control subjects, with 94% sensitivity and 98.3% specificity. Glycolipids of Mycobacterium tuberculosis H37Rv antigens were isolated, purified, and characterized. After interchelation with liposome particles, these purified antigens specifically bound to the antiglycolipid antibodies present in the sera of patients with tuberculosis, resulting in the formation of a blue agglutination. This protocol clearly differentiates healthy controls and M. bovis BCG-vaccinated subjects from those with active tuberculosis. The resultant diagnostic tool, the TB Screen Test, is more economical and rapid (4 min) than other currently available products and can be used for the mass screening of a heavily afflicted population.

Agglutination Tests↗
PubMed2005

Hydroxyl radical formation resulting from the interaction of nickel complexes of L-histidine, glutathione or L-cysteine and hydrogen peroxide.

L-histidine, L-cysteine, reduced glutathione (GSH) and other bioligands, which are ubiquitously present in biological systems, are recognized as antioxidants. Studies have shown that nickel (II) complexed with these ligands catalyzes the disproportionation of H2O2, leading to the generation of hydroxyl radicals (OH radical). However, none of the studies could provide information regarding effective concentrations at which these ligands act either as pro-oxidant or antioxidant. Therefore, the observed paradoxical behaviour of biological antioxidants in nickel-induced oxidative response was evaluated. Benzoic acid (BA) is hydroxylated by OH radical to form highly fluorescent dihydroxy benzoate (OH-BA). We used this model to study the effect of nickel complexes of L-histidine, GSH or L-cysteine on the hydroxylation of BA. The concentration-dependent effect of L-histidine, GSH and L-cysteine, or nickel on the hydroxylation of BA was studied. The hydroxylation of BA was significantly enhanced up to 1:0.5 molar ratio (Ni:hist or GSH). However, beyond 1:0.5 molar ratios, histidine/GSH inhibited the hydroxylation and complete inhibition was observed at 1:1 molar ratios. Sorbitol and caffeic acid, considered as scavengers of hydroxyl radicals, inhibited nickel-induced hydroxylation of BA. The present study demonstrates paradoxical behaviour of these bioligands. They act as pro-oxidant at lower ligand ratios and as antioxidant at higher ligand ratios. The redox properties of nickel complexes with histidine, GSH or cysteine reported here may be crucial for the toxicity of nickel.

Antioxidants↗
PubMed2005

Radiolabeling and biological evaluation of DOTA-Ph-Al derivative conjugated to anti-EGFR antibody ior egf/r3 for targeted tumor imaging and therapy.

An appropriate bifunctional chelating agent namely DOTA-Ph-Al was developed for the conjugation with biological vectors (anti EGFr antibody). We hereby report the synthesis of p-bromoacetamidobenzyl derivative of DOTA and its conjugation to monoclonal antibody anti-EGFR ior egf/r3. Immunoconjugate was prepared by conjugation of p-bromoacetamidobenzyl derivative of DOTA with ior egf/r3. Modified antibody was purified by size exclusion chromatography. DOTA-Ph-Al-ior egf/r3 exhibited quantitative 99mTc-labeling (>96%) with specific activity 10-20 mCi/mg of protein and 90Y-labeling with specific activity 2-5 mCi/mg. Immunoreactivity was determined by flow cytometry. Receptor ligand assay on murine cell line EAT and human tumor cell line U-87MG showed Kd = 2.87 nM and 4.86 nM respectively. The stability in serum indicated that 99mTc remained bound to antibodies up to 24h and 98% 90Y was associated with the mAb for five days. Biodistribution characteristics of Ab-conjugate radiolabeled to 99mTc and 90Y radionuclide was examined in BALB/c mice grafted with EAT and athymic mice with U-87MG cell line demonstrated high tumor uptake with 5.5 +/- 1.3 and 7.85 +/- 1.2%ID/g at four and 24 h for 99mTc- DOTA-Ph-AI-ior egf/r3 in EAT tumors after post injection respectively. Maximal radiotracer uptake peaked 17.6 +/- 2.5%ID/g in EAT tumor and 12.89 +/- 0.66% ID/g in U-87MG tumor at 48h for 90Y. The drug excreted through renal routes as the activity in the kidneys was 13.42 +/- 0.33%ID/g at 1 h and 4.51 +/- 1.2%ID/g at 4 h for 99mTc- DOTA-Ph-Al-ior egf/r3.

Acetamides↗
PubMed2004

Enhancement of paclitaxel-induced microtubule stabilization, mitotic arrest, and apoptosis by the microtubule-targeting agent EM012.

EM012, a semisynthetic phthalideisoquinoline alkaloid, has been recently found to target microtubules and possess anti-cancer activity. In this study, we evaluated the effects of EM012 in combination with the classic microtubule-targeting agent paclitaxel. Our results demonstrated that EM012 enhanced the anti-proliferative activity of nanomolar concentrations of paclitaxel in human breast cancer (MCF7), prostate cancer (DU145), and non-small-cell lung cancer (A549) cells. Further studies revealed that EM012 increased the ability of nanomolar concentrations of paclitaxel to induce mitotic arrest and apoptosis, without affecting microtubule polymerization. In contrast, when micromolar concentrations of paclitaxel were used, EM012 promoted paclitaxel-induced microtubule polymerization both in vitro and in cultured cells. Nevertheless, EM012 enhanced the ability of nanomolar concentrations of paclitaxel to stabilize microtubules, as indicated by increased tubulin acetylation. Our results therefore suggest a therapeutic potential of EM012/paclitaxel combination in the management of human cancer and provide mechanistic insights into the combined effects of these two microtubule-targeting agents.

Antineoplastic Agents, Phytogenic↗