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Biomedical subjects

S Srinivasan

Publications and source records attributed to S Srinivasan.

341 records · Page 19Linked to original sources
PubMedDate not supplied

Immunological detection of nitrosative stress-mediated modified Tamm-Horsfall glycoprotein (THP) in calcium oxalate stone formers.

The generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in hyperoxaluric condition has been proved experimentally. This may result in the formation of the cytotoxic metabolite peroxynitrite, which is capable of causing lipid peroxidation and protein modification. The presence of nitrotyrosine in proteins has been associated with several pathological conditions. The present study investigated the presence of nitrotyrosine in the stone formers Tamm-Horsfall glycoprotein (THP). In vitro nitration of control THP was carried out using peroxynitrite. New Zealand white rabbits were immunized with peroxynitrated THP at 15-day intervals. Antisera collected following the third immunization were assayed for antibody titres using solid-phase ELISA. Antibodies were purified by affinity chromatography. The carbonyl content of control, stone formers and nitrated THP were determined. Western blotting was carried with control, stone formers and nitrated THPs. Immunodiffusion studies demonstrated cross-reaction with nitrated bovine serum albumin. Significant amounts (p < 0.001) of carbonyl content were present in both stone formers and nitrated THPs. Western blot analysis confirmed the presence of nitrated amino acid 3-nitrotyrosine in stone formers, which could bring about structural and functional modifications of THP in hyperoxaluric patients. A cross-reaction with nitrated bovine serum albumin confirms that the raised antibody has certain paratopes similar to the epitope of nitrated protein molecules. Detection of 3-nitrotyrosine in stone formers THP indicates that it is one of the key factors influencing the conversion of THP to a structurally and immunologically altered form during calcium oxalate stone formation.

Animals↗
PubMedDate not supplied

Bicyclic nucleoside inhibitors of varicella-zoster virus (VZV): effect of terminal unsaturation in the side-chain.

As part of an ongoing research program, we have prepared novel bicyclic nucleoside inhibitors bearing long alkyl side-chains for evaluation against VZV. In particular, we report the synthesis of analogues with terminal unsaturation in the side-chain. Terminal alkenyl derivatives were found to be potent antivirals whereas the terminal alkynyls displayed poor activity.

Antiviral Agents↗
PubMedDate not supplied

Effect of eltroxine and neomercazol on monoamine oxidase from rat tissues.

The paper describes the effect of two drugs, (Eltroxine and Neomercazol) on the nature and activity of monoamine oxidase (MAO) in albino rats. Four organs namely liver, kidney, brain and heart were examined from this point of view. Biological activity measurements were done using tyramine hydrochloride as the substrate. The liver MAO from normal as well as the drug treated rats were subjected to DEAE gel filtration studies. These investigations show that there is a significant difference in the biological activity as well as in the actual nature of the enzyme as a result of treatment with the drugs mentioned above.

Animals↗
PubMedDate not supplied

Optical coherence tomography in the diagnosis of subclinical serous detachment of the macula secondary to a choroidal nevus.

We present a case in which optical coherence tomography (OCT) aided in the diagnosis of subretinal fluid (SRF) secondary to a choroidal nevus. A patient with a raised lesion above the left optic disc and distorted central vision was referred to our unit because of suspected choroidal melanoma. Fundus fluorescein angiography and slit-lamp investigation did not indicate any areas of SRF; however, OCT showed serous detachment in the macular area. The lesion was treated with laser photocoagulation and, when reviewed at four weeks post-treatment, repeat OCT scans showed that the area of SRF had cleared. In this case OCT was able to detect a subclinical serous detachment in the macula. This may have important implications in the monitoring of patients with small suspicious lesions.

Aged↗
PubMedDate not supplied

Effects of Co60 gamma radiations on the conduction properties of frog sciatic nerves.

The effect of Co60 gamma radiations on the amplitude, detection period and duration of the action potential of sciatic nerves of Rana Tigrina frogs have been studied. Dose levels of up to 120 KR were employed. Irradiation of the nerves with dose levels upto 30 KR does not seem to affect the action potential profiles. The amplitude falls rapidly therafter, registering less than 5% of the orginal value after irradiation by a dose of 120 KR. Qualitatively similar behaviour is seen in the case of detection period and duration of action potential. These results are examined in the light of the authors' data (11) on the effect of Co60 gamma rays on the enzyme acethlcholinesterase (AchE). Portions of this paper have already been communicated (12).

Action Potentials↗
PubMedDate not supplied

Vernal ulcer.

Vernal ulcer is a rare entity not reported in Indian ophthalmic literature. 76 patients in the age group ranging from 3-43 years diagnosed as having vernal conjunctivitis had been referred from general ophthalmology clinic to cornea service of the same institute during 1988-89. Among them 60 were males and 16 were females. 55 of the 76 patients had corneal involvement in the form of vernal keratitis or vernal ulcer. 16 had typical vernal ulcers. vernal ulcer was found more in the palpebral type of vernal conjunctivitis and affects males more frequently. One patient had an inferior vernal ulcer. It also occurred in the bulbar type of spring catarrh.

Adolescent↗
PubMedDate not supplied

Isolation and characterization of monoamine oxidase from hyperfunctioning human thyroid.

Human thyroid monoamine oxidase from hyperfunctioning thyroids was isolated and purified by separating the mitochondria by differential centrifugation followed by ultrasonication. The suspension containing the active enzyme from the DEAE-column, on passing through a Sephadex G-200 column gave three peaks corresponding to molecular weights of approximately 220,000, 23,000 and 4000 of which the component with molecular weight 4000 showed enzyme activity. The blood of the patients was analyzed for plasma MAO, RBC cholinesterase, plasma histaminase and plasma catecholamines. Histology and histochemistry of the thyroid tissues were also done. The data are examined from the point of view of the prevalent idea of the possible existence of MAO in multiple forms.

Adolescent↗
PubMedDate not supplied

Antibodies to Cag A protein are not predictive of serious gastroduodenal disease in Indian patients.

OBJECTIVE: The present study was aimed at assessing the predictive utility of anti-Cag A antibodies in differentiating patients of duodenal ulcer (DU) and non ulcer dyspepsia (NUD) from asymptomatic controls in a developing country. METHODS: Sera from 120 subjects were tested for antibodies to Cag A using the immunodominant portion of a recombinant 37.5 kDa fusion protein by ELISA, in endoscopically proven cases of DU and NUD and healthy controls. RESULTS: The observed optical density (OD) in DU and NUD patients was 1,947 and 1,960 respectively, which was higher than that observed in controls (p < 0.01), but there was no difference in the anti-Cag A antibody titers between DU and NUD patients. CONCLUSION: Anti-Cag A antibodies do not seem to discriminate duodenal ulcer patients from non ulcer dyspepsia in the Indian population.

Adult↗