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T N Rao

Publications and source records attributed to T N Rao.

At least 19 recordsLinked to original sources
PubMed2000

Electrochemical oxidation of histamine and serotonin at highly boron-doped diamond electrodes.

The electrochemistry of histamine and serotonin in neutral aqueous media (pH 7.2) was investigated using polycrystalline, boron-doped diamond thin-film electrodes. Cyclic voltammetry, hydrodynamic voltammetry, and flow injection analysis (FIA) with amperometric detection were used to study the oxidation reactions. Comparison experiments were carried out using polished glassy carbon (GC) electrodes. At diamond electrodes, highly reproducible and well-defined cyclic voltammograms were obtained for histamine with a peak potential at 1.40 V vs SCE. The voltammetric signal-to-background ratios obtained at diamond were 1 order of magnitude higher than those obtained for GC electrodes at and above 100 microM analyte concentrations. A linear dynamic range of 3-4 orders of magnitude and a detection limit of 1 microM were observed in the voltammetric measurements. Well-defined sweep rate-dependent voltammograms were also obtained for 5-hydroxytryptamine (5-HT). The characteristics of the voltammogram indicated lack of adsorption of its oxidation products on the surface. No fouling or deactivation of the electrode was observed within the experimental time of several hours. A detection limit of 0.5 microM (signal-to-noise ratio 13.8) for histamine was obtained by use of the FIA technique with a diamond electrode. A remarkably low detection limit (10 nM) was obtained for 5-HT on diamond by the same method. Diamond electrodes exhibited a linear dynamic range from 10 nM to 100 microM for 5-HT determination and a range of 0.5-100 microM for histamine determination. The FIA response was very reproducible from film to film, and the response variability was below 7% at the actual detection limits.

Boron↗
PubMed1999

Microbiologic spectrum and susceptibility of isolates: part I. Postoperative endophthalmitis. Endophthalmitis Research Group.

PURPOSE: To present the microbial spectrum and susceptibilities of isolates in postoperative endophthalmitis. METHOD: Isolates from 206 eyes of 206 patients who underwent vitrectomy for postoperative endophthalmitis were examined. RESULTS: One-hundred twelve (54.4%) of 206 vitreous samples were culture positive and 14 (12.5%) of 112 culture-positive cases were polymicrobial, yielding a total of 126 isolates. Isolates included 59 (46.8%) gram-positive cocci, eight (6.3%) gram-positive bacilli, 33 (26.2%) gram-negative organisms, five (4.0%) Actino-mycetes-related organisms, and 21 (16.7%) fungi. Susceptibilities to amikacin, ceftazidime, chloramphenicol, cefazolin, ciprofloxacin, gentamicin, and vancomycin are reported. CONCLUSIONS: This is the largest, single-center, prospective series on microbial susceptibilities in postoperative endophthalmitis. We report a high prevalence of gram-negative species and fungi, suggesting that empiric therapy should include coverage for gram-negative pathogens and for fungal pathogens in appropriate settings.

Anti-Bacterial Agents↗
PubMed1999

Microbiologic spectrum and susceptibility of isolates: part II. Posttraumatic endophthalmitis. Endophthalmitis Research Group.

PURPOSE: To present the microbial spectrum and susceptibilities of isolates in posttraumatic endophthalmitis. METHOD: Isolates from 182 eyes of 182 patients who underwent vitrectomy for posttraumatic endophthalmitis were examined. RESULTS: One hundred thirteen (62.1%) of 182 vitreous samples were culture-positive, and 23 (20.4%) of 113 culture-positive cases were polymicrobial, including three (2.7%) trimicrobial cases, yielding a total of 139 isolates. Isolates included 63 (45.3%) gram-positive cocci, 24 (17.3%) gram-positive bacilli, 25 (18.0%) gram-negative organisms, seven (5.0%) Actinomycetes-related organisms, and 20 (14.4%) fungi. Susceptibilities to amikacin, ceftazidime, chloramphenicol, cefazolin, ciprofloxacin, gentamicin, and vancomycin are reported. CONCLUSIONS: This study represents a large series on microbial spectrum and susceptibilities in posttraumatic endophthalmitis. We report a high prevalence of gram-positive bacilli species and polymicrobial infections containing gram-negative species, underscoring the importance of broad-spectrum, combination antibiotics in the empiric treatment of posttraumatic endophthalmitis.

Anti-Bacterial Agents↗
PubMed1999

CSF orbitorrhoea with tension pneumocephalus.

A seventy eight year old man sustained penetrating injury to right orbit about 15 years ago. Later he developed right orbital infection leading to phthisis bulbi. Two months before admission he developed CSF leak from the right orbit, tension pneumocephalous and meningitis. A rare case of CSF orbitorrhoea is reported here along with the discussion on mechanisms and management.

Aged↗
PubMed1996

Purification and characterization of a recombinant human thyroid peroxidase expressed in insect cells.

Thyroid peroxidase (TPO) is an essential enzyme for thyroid hormone biosynthesis and is an autoantigen against which antibodies are found in a number of autoimmune thyroid disorders. Large quantities of pure TPO are essential for understanding its structure and role in normal thyroid function and thyroid diseases. In this study, we describe the production of human TPO (hTPO) using a baculovirus expression vector in insect cells. TPO was sequentially extracted from insect cells using various buffers and the protein was purified to homogeneity on a C4 reversed-phase semipreparative column using high-performance liquid chromatography. The purified protein was identified as hTPO by enzyme-linked immunosorbent assay, Western blot, and amino acid sequence analyses. Carbohydrate analysis of the recombinant hTPO showed that the protein is glycosylated and mannose is the major oligosaccharide. We have extended the carbohydrate analysis by establishing the occurrence of N-acetyl galactosamine which suggested that the recombinant hTPO might contain O-glycosyl moieties. Purified hTPO reacted specifically with sera from patients with Hashimoto's thyroiditis. Crude as well as purified hTPO did not show any enzymatic activity when produced in Sf9 insect cells grown in serum free medium. In contrast, hTPO produced in the presence of 10% fetal bovine serum containing 1 microgram/ml of haematin was enzymatically active. However, the enzymatic activity of the recombinant hTPO was lower than that often found with hTPO purified from thyroid tissue. Availability of purified hTPO in relatively large quantities should allow further structural and immunological studies.

Amino Acid Sequence↗
PubMed1991

Development and biologic evaluation of a kit for preformed chelate technetium-99m radiolabeling of an antibody Fab fragment using a diamide dimercaptide chelating agent.

A kit has been developed for 99mTc antibody radiolabeling via defined chemistry using an N2S2 diamide dimercaptide bifunctional chelating agent and the performed chelate method. The process involved efficient transchelation of 99mTc from gluconate to 2,3,5,6-tetrafluorophenyl 4,5-bis-S-(1-ethoxyethyl) mercaptoacetamidopentanoate as an active ester ligand and subsequent conjugation to antibody lysine amine functional groups. The use of the ethoxyethyl group for sulfur protection allowed optimum yields of 99mTc N2S2 chelate formation with complete retention of the active ester. Subsequent addition of antibody Fab fragment gave 99mTc chelate conjugates indistinguishable from the stepwise in situ esterification and purification of the 99mTc N2S2 complex followed by conjugation as previously shown to give stable 99mTc antibody fragments with retained immunoreactivity and tumor-targeting properties.

Amino Acids, Diamino↗
PubMed1988

Specific and stable labeling of antibodies with technetium-99m with a diamide dithiolate chelating agent.

Technetium-99m labeling of antibodies has been suboptimal because of low affinity adventitious binding, nonspecific labeling, and loss of immunoreactivity. The diamide dithiolate ligand system (N2S2) forms highly stable, well-defined tetradentate complexes with Tc(V). Antibodies and their fragments have been labeled by conjugation of preformed 99mTc-4,5-bis(thioacetamido)pentanoate active ester to protein amine groups to give a chemically known 99mTc-N2S2 complex covalently linked to antibody. Evaluations of the 99mTc-N2S2-bound antibodies and their fragments have shown high stability and retained immunoreactivity.

Animals↗
PubMed1985

Synthesis and spectroscopic and fungicidal characterization of hydroxamic acids and their metal chelates.

Hydroxamic acid chelates of the type ML2, ML2', and ML2" where M = Cu(II), Ni(II) or Co(II) and L = N,2'-diphenylacetohydroxamic acid (N,2'-DPAHA), L' = 2,2'-diphenylacetohydroxamic acid (2,2'-DPAHA), and L" = 2-phenylacetohydroxamic acid (2-PAHA) have been isolated and characterized on the basis of elemental analysis and infrared and magnetic data. These metal chelates were screened for their fungicidal activity. The testing against fungi has been carried out by slide germination technique against Alternaria alternata and by inhibition zone technique against Fusarium oxysporum and Aspergillus flavus. The fungicidal activity of chelates and their parent ligand has been compared with the commercial fungicide, Dithane M-45, screened under similar conditions.

Antifungal Agents↗
PubMed1981

Effect of DDT on adipose tissue lipolysis in rat.

The effect of acute (600 mg/kg body wt) and chronic (15 mg/kg body wt/day for 45 days) 1,1,1-trichloro-2,2-bis (p-chlorophenyl)ethane (DDT) treatments of albino rats on the lipolytic activity of the adipose tissue was studied. There was no effect on the rate of glycerol release on incubation of isolated epididymal fat pads of the treated animals when compared to that of controls. Similarly, in vitro addition of DDT (10-4M) (35.4 ppm) to the fat pads did not alter their lipolytic response. Noradrenaline (NA) stimulated lipolysis, in fat pads, was also unaffected by in vitro addition of DDT. Basal as well as NA or caffeine stimulated lipolysis in isolated fat cells also remained unchanged in the presence of DDT over a range of concentrations from 10-8 M to 10-4 M.

Adipose Tissue↗
PubMed1981

Effect of DDT on adipose tissue lipolysis in rat.

The effect of acute (600 mg/kg body wt) and chronic (15 mg/kg body wt/day for 45 days) DDT treatments of albino rats on the lipolytic activity of the adipose tissue was studied. There was no effect on the rate of glycerol release on incubation of isolated epididymal fat pads of the treated animals when compared to that of controls. Similarly, in vitro addition of DDT (10(-4) M) to the fat pads did not alter their lipolytic response. Noradrenaline stimulated lipolysis, in fat pads, was also unaffected by in vitro addition of DDT. Basal as well as noradrenaline or caffeine stimulated lipolysis in isolated fat cells also remained unchanged in the presence of DDT over a range of concentrations from 10(-8) M to 10(-4) M.

Adipose Tissue↗
PubMed1981

Effect of a single oral dose of DDT on lipid metabolism in rat.

A single oral dose of 1,1,1-trichloro-2-2-bis (p-chlorophenyl)ethane (DDT) (600 mg/kg body weight) was given to rats and the levels of various lipids in adipose tissue, liver and plasma were studied. No alteration was observed in the levels of various lipid classes in these tissues except for a decrease in the phospholipid and triglyceride fractions in liver. Lipoprotein lipase activity of post-heparin plasma (protamine-sensitive and -resistant) was significantly decreased, whereas in liver and adipose tissue, the activity of this enzyme remained unchanged.

Adipose Tissue↗
PubMed1980

Acute exposure of rhesus monkeys to DDT: effect on carbohydrate metabolism.

The administration of a single oral dose of DDT (150 mg/kg body wt.) to rhesus monkey elevated the hepatic glycogen and glycogen synthase activity but depressed the glycogen phosphorylase activity. A decrease in adenylate cyclase, both basal as well as fluoride and norepinephrine stimulated activity, was observed in liver of DDT-treated animals as compared to controls. Gluconeogenic enzymes did not record any significant change in the liver.

Adenylyl Cyclases↗