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Biomedical subjects

R Govindarajan

Publications and source records attributed to R Govindarajan.

At least 19 recordsLinked to original sources
PubMed2006

Antimicrobial activity of some Indian mosses.

The present study was designed to evaluate the antimicrobial activity of ethanolic extracts of 15 Indian mosses. The antibacterial activity of ethanolic extracts was investigated against five G(+) and six G(-) bacterial strains. Antimycotic activity was assayed against 8 fungi. Sphagnum junghuhnianum, Barbula javanica, Barbula arcuata, Brachythecium populeum, Brachythecium rutabulum, Mnium marginatum and Entodon cf rubicundus were found to be most active against all the organisms.

Anti-Bacterial Agents↗
PubMed2006

High-performance liquid chromatographic method for the quantification of phenolics in 'Chyavanprash' a potent Ayurvedic drug.

Quantification of bioactive principles through modern analytical tools is essential for establishing the authenticity, credibility, prescription and usage of Ayurvedic medicines/herbal formulations. 'Chyavanprash' is one of the oldest and most popular Ayurvedic preparations, used widely as a health promotive and disease preventive 'Rasayana' drug in India and elsewhere. The rejuvenating and tonic properties of 'Chavanprash' are considered mainly due to their antioxidant principles, which in turn is due to the presence of phenolic compounds. A simple high-performance liquid chromatography (HPLC) method for the separation and quantitative determination of the major antioxidant compounds from 'Chyavanprash' has been developed. The use of Waters Symmetry column and an acidic mobile phase enabled the efficient separation of phenolic compounds (catechin, quercetin-3-O-rutinoside, syringic acid and gallic acid) within a 35 min analysis. Validation of the method was done with a view to demonstrate its selectivity, linearity, precision, accuracy and robustness. In addition optimization of the complete extraction of phenolic compounds were also studied.

Antioxidants↗
PubMed2006

Phytochelatin synthesis and response of antioxidants during cadmium stress in Bacopa monnieri L.

The phytotoxicity imposed by cadmium (Cd) and its detoxifying responses of Bacopa monnieri L. have been investigated. Effect on biomass, photosynthetic pigments and protein level were evaluated as gross effect, while lipid peroxidation and electrolyte leakage reflected oxidative stress. Induction of phytochelatins and enzymatic and non-enzymatic antioxidants were monitored as plants primary and secondary metal detoxifying responses, respectively. Plants accumulated substantial amount of Cd in different plant parts (root, stem and leaf), the maximum being in roots (9240.11 microg g(-1) dw after 7 d at 100 microM). Cadmium induced oxidative stress, which was indicated by increase in lipid peroxidation and electrical conductivity with increase in metal concentration and exposure duration. Photosynthetic pigments showed progressive decline while protein showed slight increase at lower concentrations. Enzymes viz., superoxide dismutase (SOD, EC 1.15.1.1), guaiacol peroxidase (GPX, EC 1.11.1.7) ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase (GR, EC 1.6.4.2) showed stimulation except catalase (CAT, EC 1.11.1.6) which showed declining trend. Initially, an enhanced level of cysteine, glutathione and non-protein thiols was observed, which depleted with increase in exposure concentration and duration. Phytochelatins induced significantly at 10 microM Cd in roots and at 50 microM Cd in leaves. The phytochelatins decreased in roots at 50 microM Cd, which may be correlated with reduced level of GSH, probably due to reduced GR activity, which exerted increased oxidative stress as also evident by the phenotypic changes in the plant like browning of roots and slight yellowing of leaves. Thus, besides synthesis of phytochelatins, availability of GSH and concerted activity of GR seem to play a central role for Bacopa plants to combat oxidative stress caused by metal and to detoxify it. Plants ability to accumulate and tolerate high amount of Cd through enhanced level of PCs and various antioxidants suggest it to be a suitable candidate for phytoremediation.

Antioxidants↗
PubMed2006

Antiulcer and antimicrobial activity of Anogeissus latifolia.

Ethnobotanically, the bark of Anogeissus latifolia (Roxb. ex DC.) Wall. ex Guill. and Perr.(Combretaceae) has been reported to be used in the treatment of various disorders including stomach and skin diseases. We studied the antiulcer potential and antimicrobial activity of the 50% aqueous alcoholic extract in order to validate ethnobotanical claims regarding the plant use in the above-mentioned disorders. Gastroprotective potential of the Anogeissus latifolia extract (ALE) (100 and 200mg/kg/body weight) was studied on aspirin, cold-resistant stress (CRS), pylorus ligated (PL) and ethanol-induced ulcers. Status of the antioxidant enzymes superoxide dismutase (SOD) and catalase along with lipid peroxidation (LPO) was also studied in CRS-induced ulcers. The results of the present study showed for the first time that the ALE possessed gastroprotective activity as evidenced by its significant inhibition in the formation of ulcers induced by physical and chemical agents with a maximum of 84.16% curation (200mg/kg body weight) in CRS-induced ulcers. ALE decreased LPO and SOD with concomitant increase in catalase activity in CRS-induced ulcers. Moderate antibacterial activity and antifungal activity was also observed. High performance thin layer chromatography (HPTLC) showed the presence of gallic acid and ellagic acid (0.95%, w/w, 0.25%, w/w, respectively) in the plant. These findings could justify, at least partially, the inclusion of this plant in the management of gastric disorders in traditional medicine.

Animals↗
PubMed2005

Action of Hygrophila auriculata against streptozotocin-induced oxidative stress.

Hygrophila auriculata (K. Schum.) Heine (Family: Acanthaceae) is a wild herb widely used in 'Ayurveda' as 'Rasayana' drug for treatment of various disorders. Treatment of diabetic rats with aerial parts of Hygrophila auriculata extract (HAEt, 100 and 250 mg/kg body weight) for 3 weeks showed significant reduction in blood glucose, thiobarbituric acid reactive substances (TBARS) and hydroperoxide in both liver and kidney. The treatment with HAEt significantly increased the glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST) and catalase (CAT) in the drug-treated group, which is comparable to the control group. HAEt and glibenclamide-treated rats also showed decreased lipid peroxidation that is associated with increased activity of superoxide dismutase (SOD) and catalase. The ability of HAEt on tissue lipid peroxidation and antioxidant status in diabetic animals has not been studied before. The result of this study thus shows that HAEt possesses significant antidiabetic activity along with potent antioxidant potential in diabetic conditions.

Acanthaceae↗
PubMed2005

Antioxidant approach to disease management and the role of 'Rasayana' herbs of Ayurveda.

The disease preventive and health promotive approach of 'Ayurveda', which takes into consideration the whole body, mind and spirit while dealing with the maintenance of health, promotion of health and treating ailments is holistic and finds increasing acceptability in many regions of the world. Ancient Ayurvedic physicians had developed certain dietary and therapeutic measures to arrest/delay ageing and rejuvenating whole functional dynamics of the body system. This revitalization and rejuvenation is known as the 'Rasayan chikitsa' (rejuvenation therapy). Traditionally, Rasayana drugs are used against a plethora of seemingly diverse disorders with no pathophysiological connections according to modern medicine. Though, this group of plants generally possesses strong antioxidant activity, only a few have been investigated in detail. Over about 100 disorders like rheumatoid arthritis, hemorrhagic shock, CVS disorders, cystic fibrosis, metabolic disorders, neurodegenerative diseases, gastrointestinal ulcerogenesis and AIDS have been reported as reactive oxygen species mediated. In this review, the role of free radicals in these diseases has been briefly reviewed. 'Rasayana' plants with potent antioxidant activity have been reviewed for their traditional uses, and mechanism of antioxidant action. Fifteen such plants have been dealt with in detail and some more plants with less work have also been reviewed briefly.

Antioxidants↗
PubMed2004

Antiulcer activity of Utleria salicifolia rhizome extract.

The effect of 50% ethanolic extract of Utleria salicifolia (USE) was assessed in different acute and chronic gastric ulcer models in rats. USE, 50-200 mg/kg administered orally, twice daily for 5 days showed dose-dependent ulcer protective effect in pylorus ligation (14.48-51.03% protection, P < 0.5 to P < 0.01), aspirin (28.80-56.52% protection, P < 0.5 to P < 0.001), ethanol (13.22-60.74% protection, P < 0.5 to P < 0.001), cold-restraint stress (21.22-77.14% protection, P < 0.05 to P < 0.001), and acetic acid (20.0-84.37% protection, P < 0.5 to P < 0.001)-induced acute and chronic ulcers. USE also significantly (P < 0.001) reduced the ulcer incidence (50 and 10%) and severity (67.83 and 91.34% protection) of duodenal ulcer, induced by cysteamine. Besides USE offered protection (53.52 and 60.58%) against ethanol-induced depletion of gastric wall mucus. However, USE reduced the ulcer index with significant decrease in plasma corticosterone (25.53 and 39.52% protection, P < 0.1 and P < 0.05), lipid peroxidation (18.75 and 47.92% protection, P < 0.01 and P < 0.001), superoxide dismutase (15.80 and 26.61% protection, P < 0.05 and P < 0.001) and increased in catalase (28.42 and 71.0% protection, P < 0.05 and P < 0.001) activity, respectively. Preliminary phytochemical screening of the USE gave the positive test for steroids, alkaloids, terpenoids, saponins and tannins. The HPTLC studies in the toluene: ethyl acetate: formic acid and the densitometric scanning at 254 nm gave three major spots with area corresponding to 28.16, 17.17, and 13.79% at 0.69, 0.78, and 0.88 R(f) values, respectively. The results indicate that USE possesses antiulcer activity.

Acetic Acid↗
PubMed2003

Free radical scavenging potential of Picrorhiza kurrooa Royle ex Benth.

For assessing free radical scavenging potential of P. kurrooa, the antioxidant activity of P. kurrooa extract was studied by lipid peroxidation assay using rat liver homogenate. The extract (1 mg/ml) showed marked protection (up to 66.68%) against peroxidation of liver phospholipids. Besides, reduced glutathione showed very encouraging activity. The extract also exhibited significant scavenging activity. Thus augmenting the wide use of plant in the indigenous system of medicine, which may partly be due to antioxidant and free radical scavening activity of the extract.

Animals↗
PubMed2001

Retardation of the onset of turbulence by minor viscosity contrasts.

Motivated by turbulent drag reduction by minute concentrations of polymers we study the effects of minor viscosity contrasts on the stability of hydrodynamic flows. The key player is a localized region where fluctuations are produced by interactions with the mean flow (the "critical layer"). We show that a layer of weakly space-dependent viscosity placed near the critical layer has a very large stabilizing effect on hydrodynamic fluctuations, retarding significantly the onset of turbulence. The effect is not due to a modified dissipation (as is assumed in theories of drag reduction) but is due to reduced energy intake from the mean flow to the fluctuations. Similar physics may act in turbulent drag reduction.

Journal Article↗
PubMed2001

HLA-DQ8 transgenic and NOD mice recognize different epitopes within the cytoplasmic region of the tyrosine phosphatase-like molecule, IA-2.

Type 1 diabetes mellitus is strongly associated with HLA-DQ8 in humans and I-A(g7) in the NOD mouse. The disease is characterized by loss of tolerance to auto-antigens such as GAD, insulin, and the protein tyrosine phosphatase-like molecule, IA-2. We identified T cell epitopes on the intracytoplasmic region of IA-2 by immunizing DQ8/NOD, DQ8/B10, and NOD mice with overlapping 18 mer peptides in CFA. We identified four peptides presented both by DQ8 and NOD, five DQ8 specific peptides, and six NOD specific peptides. Both mouse lines failed to respond to ten peptides. We demonstrated MHC class II and CD4 restriction of proliferative responses using appropriate blocking antibodies. To understand the role of non-MHC genes in the generation of immune response to the islet auto-antigen, we evaluated cytokine secretion following immunization of DQ8 transgenic mice with strongly immunogenic peptides. The NOD background resulted in increased secretion of cytokines. In conclusion, we have identified IA-2 peptides that induce lymphoproliferative responses in DQ8 transgenic and NOD mice and shown that these peptides stimulate production of Th1 and Th2 cytokines.

Amino Acid Sequence↗
PubMed2001

Clinics in diagnostic imaging (66). Right complete branchial fistula.

We report a case of complete branchial fistula in an 18-year-old woman which could be demonstrated by a contrast study. The tract was completely excised and the patient had an uneventful recovery. Branchial fistulae are formed due to the persistence of the embryonic second branchial cleft. Complete fistulae with the internal opening in the region of the tonsillar fossa are not common.

Adolescent↗
PubMed2000

Effect of thalidomide on gastrointestinal toxic effects of irinotecan.

Irinotecan is the only accepted second-line treatment for colorectal cancer in the USA. Doses are, however, frequently limited by associated late-onset diarrhoea. Thalidomide has antiangiogenic and immunomodulatory properties and is being investigated as an antineoplastic. We did a pilot study of combination therapy with thalidomide and irinotecan for metastatic colorectal cancer. In an interim analysis of nine patients, thalidomide had almost eliminated the dose-limiting gastrointestinal toxic effects of irinotecan, especially diarrhoea and nausea (each p<0.0001), and eight of nine patients were able to complete the chemotherapy course.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Melanosomal proteins promote melanin polymerization.

In melanocytes, enzymes involved in the generation of melanin monomers are present and active in coated vesicles which are known to be acidic. Melanin polymerization however, occurs only in melanosomes. In vitro, it is not possible to generate melanin at the acidic pH of melanosomes using 3,4-dihydroxyphenylalanine (DOPA) and tyrosinase alone whereas melanin readily forms at higher pH with these reagents. Dimerization and elongation of the melanin polymer is known to require deprotonation. We have hypothesized that the amino acid side chains of melanosomal proteins act as proton acceptors to initiate polymerization and that the protonated basic groups serve to attract the negatively charged oligomers thus aiding polymerization and binding to proteins. We show that basic model proteins and basic premelanosomal proteins promote polymerization at an acidic pH and that positively charged surfaces allow binding of the growing melanin polymer. With progressive polymerization and exhaustion of the proton abstracting ability of melanosomal proteins, melanosomal pH drops further, which, we argue, is an additional controlling step that limits tyrosinase activity and melanin polymerization.

Animals↗
PubMed2000

Irinotecan and thalidomide in metastatic colorectal cancer.

Fifteen patients with metastatic colorectal cancer were treated with irinotecan (CPT-11, Camptosar) at 300 to 350 mg/m2 every 21 days and thalidomide (Thalomid) at 400 mg/d. Of the 15 patients, 11 were in a pilot study and 4 were in an ongoing phase II protocol. There were 12 men and 3 women, with a median age of 56 years (range: 29 to 79 years). Patients were treated with a median of three cycles (range: one to eight cycles). The four patients enrolled in the formal protocol were not evaluable for response at the time of this report. Of the 11 patients in the pilot study, 10 were evaluable for response; there were two complete responses, two partial responses, and six progressions. Investigators noted a remarkable absence of grade 3/4 gastrointestinal toxicities, and concluded that further testing of the complete response and toxicity profile of the irinotecan/thalidomide regimen was warranted.

Adult↗
PubMed1997

Thymidine kinase (TK) gene-transduced human lymphocytes can be highly purified, remain fully functional, and are killed efficiently with ganciclovir.

A graft-versus-leukemia (GVL) effect has been considered a major factor responsible for cures in patients with hematologic malignancies undergoing allogeneic bone marrow transplantation; however, associated graft-versus-host disease (GVHD) results in significant morbidity and mortality. T-cell depletion reduces the incidence and severity of GVHD but eliminates, at least partially, the GVL effect. Reinfusion of donor T lymphocytes at relapse posttransplantation can induce a potent antitumor response, but GVHD still occurs in the majority of patients. Prior transduction of T lymphocytes with the suicide gene, the viral thymidine kinase (TK), permits specific cell kill on administration of ganciclovir (GCV). Therefore, infusion of TK-transduced T lymphocytes may induce GVL effect and allow for their subsequent selective elimination in case GVHD develops. To evaluate the efficacy and feasibility of this promising approach, anti-CD3-stimulated primary human lymphocytes cultured in interleukin-2 were TK-transduced by a retroviral vector carrying both TK and neomycin-resistance genes. After selection in G418, more than 90% of the cells contained the TK gene as shown by a semiquantitative polymerase chain reaction. In addition, 1 to 5 days of GCV exposure, at clinically achievable concentrations of 20 to 50 micromol/L, induced > or = 90% killing of G418-selected cells without affecting nontransduced cells. Correlation of the extent of T-cell kill and the proportion of TK-gene-transduced cells is consistent with the absence of a bystander effect. Transduced cells were CD3+ and either CD8+ or CD4+ and retained functional properties of untransduced cells. In vivo administration of GCV prevented tumor development after subcutaneous injection of TK-transduced murine myeloma cells (MOPC-11), whereas such an effect was not observed on injection of untransduced cells into the opposite flank. Our studies provide critical information that (1) adequate numbers of TK-transduced lymphocytes can be selected efficiently with > or = 90% purity, (2) selected cells remain functional, (3) 24 hours of exposure to GCV at clinically achievable concentration effects > or = 90% killing of selected cells, and (4) GCV is effective in vivo in killing TK-transduced cells. Based on these data, a clinical study has been initiated in patients with multiple myeloma with persistent or relapsing disease after T-cell-depleted allogeneic transplants.

Animals↗