Search PubMed⌕ Search

Biomedical subjects

A R Reddy

Publications and source records attributed to A R Reddy.

At least 19 recordsLinked to original sources
PubMed2005

Tuberculosis: an under-diagnosed aetiological agent in uveitis with an effective treatment.

PURPOSE: To highlight the diversity of clinical presentations with tubercular uveitis in a nonendemic setting, and discuss the diagnostic approach and an effective treatment. METHOD: Descriptive case series. RESULTS: A total of 12 cases of varied presentations of tubercular uveitis diagnosed over a period of 1 year of which six cases are described in detail. Presentations included choroidal tuberculomas, multifocal choroiditis, recurrent granulomatous uveitis, panuveitis with cystoid macular oedema, and serpiginous choroiditis. All cases had a chronic or recurrent course and responded very well to antitubercular treatment. Diagnosis was mainly assisted by positive tuberculin testing. CONCLUSION: A high index of suspicion helps diagnose ocular tuberculosis in areas of low prevalence of the disease. It forms part of the differential diagnosis of any chronic or recurrent uveitis, especially in an at-risk patient. Antitubercular treatment seems highly effective.

Adolescent↗
PubMed2004

Structural characterization of impurities in pioglitazone.

In the pioglitazone bulk drug three prominent impurities I-III were detected up to concentrations of 0.1% (ranging from 0.05-0.1%) by reversed phase HPLC. These impurities were isolated from enriched mother liquor samples and characterized as 5-(4-hydroxybenzyl)-1,3-thiazolidine-2,4-dione (I) 5-(4-fluorobenzyl)-1,3-thiazolidine-2,4-dione (II), 2-[2-(4-bromophenoxy) ethyl-5-ethyl pyridine (III) based on their 1H, and 13C NMR, DEPT, Mass and IR spectral data. Structure elucidation and synthesis of these impurities is discussed.

Chromatography, High Pressure Liquid↗
PubMed2002

The cell morphogenesis gene ANGUSTIFOLIA encodes a CtBP/BARS-like protein and is involved in the control of the microtubule cytoskeleton.

The ANGUSTIFOLIA (AN) gene is required for leaf hair (trichome) branching and is also involved in polarized expansion underlying organ shape. Here we show that the AN gene encodes a C-terminal binding proteins/brefeldin A ADP-ribosylated substrates (CtBP/BARS) related protein. AN is expressed at low levels in all organs and the AN protein is localized in the cytoplasm. In an mutant trichomes, the organization of the actin cytoskeleton is normal but the distribution of microtubules is aberrant. A role of AN in the control of the microtubule cytoskeleton is further supported by the finding that AN genetically and physically interacts with ZWICHEL, a kinesin motor molecule involved in trichome branching. Our data suggest that CtBP/BARS-like protein function in plants is directly associated with the microtubule cytoskeleton.

Alcohol Oxidoreductases↗
PubMed2000

Requirements for double-strand cleavage by chimeric restriction enzymes with zinc finger DNA-recognition domains.

This study concerns chimeric restriction enzymes that are hybrids between a zinc finger DNA-binding domain and the non-specific DNA-cleavage domain from the natural restriction enzyme FOK:I. Because of the flexibility of DNA recognition by zinc fingers, these enzymes are potential tools for cleaving DNA at arbitrarily selected sequences. Efficient double-strand cleavage by the chimeric nucleases requires two binding sites in close proximity. When cuts were mapped on the DNA strands, it was found that they occur in pairs separated by approximately 4 bp with a 5' overhang, as for native FOK:I. Furthermore, amino acid changes in the dimer interface of the cleavage domain abolished activity. These results reflect a requirement for dimerization of the cleavage domain. The dependence of cleavage efficiency on the distance between two inverted binding sites was determined and both upper and lower limits were defined. Two different zinc finger combinations binding to non-identical sites also supported specific cleavage. Molecular modeling was employed to gain insight into the precise location of the cut sites. These results define requirements for effective targets of chimeric nucleases and will guide the design of novel specificities for directed DNA cleavage in vitro and in vivo.

Amino Acid Sequence↗
PubMed2000

Photosynthesis and kinetic characteristics of rubisco in Hibiscus cannabinus L.

Photosynthetic characteristics in kenaf (Hibiscus cannabinus L.), a C3 plant, were compared with Abelmoschus esculentus (L.) Moench, another member of Malvaceae. Kenaf leaves exhibited significantly higher rate of photosynthesis (40 mg CO2 dm(-2) hr(-1)) which was 24.6 mg dm(-2) hr(-1) in A. esculentus. Rate of photo and dark respiration was similar in both the species. Kenaf leaf photosynthesis had a higher optimum temperature (32 degrees C) than that of A. esculentus (26 degrees C). Photosynthesis in kenaf leaves required higher saturation irradiance (1,600 micromole m(-2) sec(-1)). There was a significant correlation between photosynthetic rate and biomass yield in these species. The primary product of photosynthesis after 5 seconds of 14C-assimilation was 3-PGA in both the species. The kinetic properties of RuBP carboxylase/oxygenase were determined in the leaf extracts. Higher carboxylase activities were recorded with kenaf leaf extracts (245 pmole mg chl(-1) hr(-1)). Km (CO2) for kenaf leaf carboxylase was significantly lower (7.8 microM) than A. esculentus (13.5 microM) and corresponding difference in Vmax values of carboxylase was recorded between the two species. The kinetic characteristics of oxygenase were similar in both the extracts. These results indicated the variation in carboxylase activity and its kinetic characteristics reflected a significant difference in CO2 assimilation in C3 plants.

Hibiscus↗
PubMed1999

A bifunctional luminogenic substrate for two luminescent enzymes: firefly luciferase and horseradish peroxidase.

Horseradish peroxidase (HRP) catalyzes the oxidative chemiluminescent reaction of luminol, and firefly luciferase catalyzes the oxidation of firefly D-luciferin. Here we report a novel substrate, 5-(5'-azoluciferinyl)-2,3-dihydro-1,4-phthalazinedione (ALPDO), that can trigger the activity of HRP and firefly luciferase in solution because it contains both luminol and luciferin functionalities. It is synthesized by diazotization of luminol and its subsequent azo coupling with firefly luciferin. NMR spectral data show that the C5' of benzothiazole in luciferin connects the diazophthalahydrazide. The electronic absorption and fluorescence properties of ALPDO are different from those of its precursor molecules. The chemiluminescence emission spectra of the conjugate substrate display biphotonic emission characteristic of azophthalatedianion and oxyluciferin. It has an optimum pH of 8.0 for maximum activity with respect to HRP as well as luciferase. At pH 8.0 the bifunctional substrate has 12 times the activity of luminol but has 7 times less activity than the firefly luciferin-luciferase system. The specific enhancement of light emission from the cyclic hydrazide part of ALPDO helped in the sensitive assay of HRP down to 2.0 x 10(-13) M and of ATP to 1.0 x 10(-14) mol. Addition of enhancers such as firefly luciferin and p-iodophenol (PIP) to the HRP-ALPDO-H2O2 system enhanced the light output.

Azo Compounds↗
PubMed1998

Opiate analgesics' dual role in firefly luciferase activity.

The effects of three opiate analgesics, isolated from opium, on the firefly luciferase enzyme have been studied. Morphine (MN), 6-acetylmorphine (MAM), and diacetylmorphine (DAM) inhibited the enzyme activity at different levels. At lower concentrations, MN and MAM enhanced enzyme activity, effecting inhibition at higher concentrations. However, DAM inhibited the enzyme activity at all concentrations investigated. The stimulating activity of MN and MAM is attributed to the hydrophilic interaction of the proton donor-acceptor type with the polar regions of the luciferase located outside the binding pocket of the active site. The inhibition at higher concentrations of MN and MAM and at all concentrations of DAM is found to be competitive in nature, with the analgesics competing for the binding of the enzyme's natural substrate luciferin. The binding site of the luciferase could accommodate only one analgesic molecule. Binding constants determined from bioluminescence studies showed that the inhibitor binding site is hydrophobic in nature. The inhibition constants of analgesics are in the order MN > MAM > DAM. The greater binding of DAM to luciferase is attributed to its ability to form a ground state complex with ATP and greater hydrophobicity. At higher concentrations of ATP, the binding constants increased. The results obtained are explained assuming that the firefly luciferase acts as a subtype mu-opioid receptor model.

Adenosine Triphosphate↗
PubMed1997

DNA helix destabilization by proline and betaine: possible role in the salinity tolerance process.

Evidence is provided for the ability of proline, a salinity induced osmoprotectant, to destabilize the double helix and lower the Tm of DNA in a concentration dependent manner. At the reported salinity-adaptive bio-accumulation of 1 M and above, proline could considerably decrease the Tm and partially counteract the effect of sodium chloride and spermidine on DNA stability. On the contrary, several other amino acids tested did not show any such destabilizing effect on DNA helix. Enhanced susceptibility to S1 nuclease and insensitivity to DNase I in presence of increasing proline concentrations have further suggested a clear destabilization of the double helix. Such an effect is somewhat reminiscent of the interaction between betaine, another salinity induced osmolyte, and DNA resulting in decreased Tm values. These interactions may be significant in view of the abundance of such osmolytes in cells under salinity stress-adapted conditions, with many a bacterial mutant accumulating them exhibiting improved tolerance to salinity.

Amino Acids↗
PubMed1996

Chalcone synthase in rice (Oryza sativa L.): detection of the CHS protein in seedlings and molecular mapping of the chs locus.

The chalcone synthase is a key enzyme that catalyses the first dedicated reaction of the flavonoid pathway in higher plants. The chs gene and its protein product in rice has been investigated. The presence of a chalcone synthase (CHS) protein in rice seedlings and its developmental stage-specific expression has been demonstrated by western analysis. The chalcone synthase of rice was found to be immunologically similar to that of maize. A rice cDNA clone, Os-chs cDNA, encoding chalcone synthase, isolated from a leaf cDNA library of an indica rice variety Purpleputtu has been mapped to the centromeric region of chromosome 11 of rice. It was mapped between RFLP markers RG2 and RG103. RG2 is the nearest RFLP marker located at a genetic distance of 3.3 cM. Some segments of chromosome 11 of rice including chs locus are conserved on chromosome 4 of maize. The markers, including chs locus on chromosome 11 of rice are located, though not in the same order, on chromosome 4 of maize. Genetic analysis of purple pigmentation in two rice lines, Abhaya and Shyamala, used in the present mapping studies, indicated the involvement of three genes, one of which has been identified as a dominant inhibitor of leaf pigmentation. The Os-chs cDNA shows extensive sequence homology, both for DNA and protein (deduced), to that of maize, barley and also to different monocots and dicots.

Acyltransferases↗
PubMed1996

Use of LMA for awake intubation for caesarean section.

PURPOSE: This case report describes the use of a Laryngeal Mask Airway in a morbidly obese parturient with the H.E.L.L.P. syndrome. An urgent Caesarean section was required because of vaginal bleeding and fetal distress. CLINICAL FEATURES: The patient was a 32 year old G3, T1, P1, L1 who presented with epigastric pain, headache, vomiting, and diarrhoea. She was hypertensive (180/110 mmHg) and thrombocytopaenic (18 x 10(-9). L-1). Examination of the airway revealed a short neck, receded jaw, full dentition, large breasts and she was considered to be a potential intubation problem. The patient required an awake intubation using a technique that minimized hypertension, aspiration risk, airway trauma, and hypoxia. A laryngeal mask was used to facilitate tracheal intubation, and the patient tolerated the procedure with no adverse outcome. CONCLUSION: The LMA has a place to facilitate potentially difficult awake tracheal intubation with the pregnant patient.

Adult↗
PubMed1996

Enhanced photosynthesis in cytozyme-treated blackgram, Phaseolus mungo L.

Foliar application of cytozyme to 30-day-old black-gram plants resulted 48% increase of dry matter accumulation. The increase in fresh and dry weights of total plants was largely due to enhanced CO2 assimilation rates which were associated with increased RuBP carboxylase activities. The photochemical characteristics in the isolated chloroplasts exhibited an increase of 32, 28 and 40%, measured as the photoreduction of DCPIP, FeCN and NADP, respectively. Cytozyme treatment also resulted an increase in the chlorophyll content in leaves.

Chlorophyll↗
PubMed1995

Formulation of the reference Indian adult: anatomic and physiologic data.

Data on heights and weights of Indian males and females of various ages are presented. The weights of specific organs obtained from post-mortem records of accident cases of Indian adults and children are also presented to provide some inputs towards formulation of an Indian Reference Man for radiation protection purposes. An intercomparison of the present data with the data available from other sources including those for ICRP Reference Man, Woman, and Child has been made. The daily intakes of air, water, and dietary constituents of an average Indian adult are also given.

Adolescent↗
PubMed1994

Proline-protein interactions: protection of structural and functional integrity of M4 lactate dehydrogenase.

A well defined labile isozyme, rabbit muscle M4-lactate dehydrogenase was denatured under freeze-thaw, heat and GuHCl treatment in the presence and absence of proline, and the corresponding structural changes of the enzyme were monitored through fluorescence and CD spectral studies. The data reveal that proline confers protection to the structural integrity of the enzyme, thereby protecting its activity. This was attributed to its property of forming hydrophilic colloids in aqueous media with a hydrophobic backbone interacting with protein. Unlike other osmolytes, proline is proposed to act on the enzyme stability not only by inducing preferential hydration of proteins but also through the interactions of its multimeric hydrophobic backbone with the solvent-accessible hydrophobic regions of the enzyme.

Animals↗
PubMed1994

Regulatory differences in developmental expression of alcohol dehydrogenase are related to interspecies differences in ethanol tolerance of Drosophila.

Biochemical properties and expression patterns of alcohol dehydrogenase were compared among members of the virilis phylad of Drosophila. Quantitative differences in stage- and tissue-specific expression of ADH of D. virilis, D. novamexicana, D. texana and D. americana were observed. These differences seem to correlate with the temporal differences in ethanol tolerance among these species. Quantitative differences in ADH protein levels account for most, if not all, of the activity differences between species. Analysis of the interspecific hybrids revealed that these differences arise by a mechanism affecting monomer synthesis. A comparison with earlier studies, where independently evolved regulatory differences were related to adaptations, revealed contrasting underlying mechanisms.

Adaptation, Physiological↗
PubMed1992

Organ weights in autopsy cases from an urban apex hospital.

The available limited anatomical and physiological data have been compiled for Indian adult as a part of ongoing efforts in the country to formulate an Indian Reference Man for radiation protection purposes. The parameters included weight, height, body surface area, weight of various organs (brain, heart, kidney, lung, liver etc.), total body water, extra-cellular water, blood volume, specific gravity, total lung capacity, vital capacity etc. The data have been drawn from post-mortem studies (566 males and 185 females) and other data from published work on 433 healthy male and 137 female volunteers. Data gaps have been filled by the method of pooling wherever necessary. This paper presents the intercomparison of the present data with the data available from other sources. The data from various Indian sources indicate a similar trend. However, a significant difference (P less than 0.01) was observed in organ weights and total body weights, in comparison to the Bhabha Atomic Research Centre (BARC) values. The present data are not comprehensive enough to suggest definitive norms of the Indian Reference Man.

Adult↗
PubMed1991

Inhibition of cellular thymidylate synthesis by cytotoxic propenal derivatives of pyrimidine bases and deoxynucleosides.

A series of cytotoxic propenal (3-oxoprop-1-enyl) derivatives of pyrimidine bases and deoxynucleosides was evaluated for their ability to block thymidylate synthesis in intact and permeabilized murine leukemia L1210 cells. Several were potent inhibitors of this process, likely contributing to their cytotoxicity. The IC50 values of thymidine-3-propenal, the prototype of this series, in intact and permeabilized L1210, L-M and L-M(TK-) cells were 21, 7.5, and 75 microM and 1.5, 1.7, and 3.5 microM, respectively. The related base analogue, thymine-1-propenal, is a product of bleomycin-induced DNA strand-scission; the results of the present study bear on the mode of action of this antibiotic.

Acrolein↗