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Biomedical subjects

R Tripathi

Publications and source records attributed to R Tripathi.

At least 19 recordsLinked to original sources
PubMed1995

Effectiveness of apraclonidine and acetazolamide in preventing postoperative intraocular pressure spikes after extracapsular cataract extraction.

We studied the effectiveness of two prophylactic agents in controlling early postoperative intraocular pressure (IOP) increases after cataract surgery. Fifty-four nonglaucomatous patients received either topical 1% apraclonidine, one drop before and after surgery, or sustained-release acetazolamide, 500 mg, or no medication at the completion of planned extracapsular cataract extraction (ECCE). Mean baseline IOPs were similar among patients randomized to the apraclonidine, acetazolamide, and control groups: 15.29 mm Hg, 15.33 mm Hg, and 14.26 mm Hg, respectively. At 3 hours postoperatively, IOPs were significantly lower in the apraclonidine group (11.13 mm Hg, P = .035), nonsignificantly lower in the acetazolamide group (13.3 mm Hg, P = .17), and significantly increased in the control group (21.32 mm Hg, P = .003). One eye in the apraclonidine group and six in the control group had IOPs greater than 30 mm Hg. At 24 hours, the only statistically significant difference was in the control group, whose mean IOPs remained elevated (21.83 mm Hg, P = .0008). One eye in the apraclonidine group, two in the acetazolamide group, and five in the control group had IOPs greater than 30 mm Hg. We found a significant early IOP reduction with apraclonidine given topically preoperatively and at the completion of planned ECCE.

Acetazolamide↗
PubMed1992

MR observations on the effects of praziquantel in neurocysticercosis.

Eight patients with neurocysticercosis treated with praziquantel (PZQ) were studied with serial MR imaging to demonstrate the early effects of the drug in brain lesions. Increase in cyst size and appearance of pericystic edema were observed as early as 24 hr, followed by gradual degeneration of the scolex and cyst contents. Cysts showed varied degree of response to the drug and in their rate of disappearance. MRI was found to be a sensitive technique to objectively document early changes in the parasite and patterns of response to the cysticidal drug in brain cysticercosis.

Adult↗
PubMed1991

Comparison of antimalarial efficacy of alpha, beta, and alpha/beta arteether against Plasmodium cynomolgi B infection in monkeys.

The blood schizontocidal activity of alpha and beta arteether has been compared with that of alpha/beta arteether (a 30:70 mixture of alpha and beta isomers), which is a fast-acting blood schizontocide undergoing phase I clinical trials at the Central Drug Research Institute. Both beta and alpha/beta arteether have comparable activity and are curative at a dose of 5 mg/kg for 3 days against blood-induced Plasmodium cynomolgi B infection in the rhesus monkey; alpha arteether alone is slightly less active, with a 50% cure rate at the above dose.

Animals↗
PubMed1990

Gametocytocidal activity of the antimalarial alpha/beta arteether against Plasmodium cynomolgi B.

A new sesquiterpene lactone alpha/beta arteether (a 30:70 mixture of enantiomers), which possesses very high blood schizontocidal activity, has been evaluated for gametocytocidal/sporontocidal action against Plasmodium cynomolgi B infection in the rhesus monkey. This paper reports gametocytocidal action of this new antimalarial drug at 2.5-5 mg/kg (single im dose) against P. cynomologi B as shown by the complete absence of mosquito infectivity. No sporontocidal action was demonstrable in the vector at a dose of up to 20-50 mg/kg im.

Animals↗
PubMed1975

Perivascular and intervascular reticular fibers of the retina.

We demonstrated the existence in the retina of an argyrophilic perivascular membrane comparable in all respects to that which exists throughout the vascular system. We compared our findings by light microscopy with those previously reported. We identified, by electron microscopy, the normal general location of the network between the basal laminae of the glial and vessel cells and demonstrated its selective staining with silver methenamine. These perivascular fibers, intercapillary strands, and bridges develop in relation to the process of retinal vascularization and the potential for forming these fibers is reactivated in senility and disease, as in diabetes. We summarized the evidence by concluding that these fibers are most likely composed of reticulin; it appears provable that in the past there may have been some confusion with neural fibers.

Age Factors↗
PubMed1975

Pathogenesis of hypertensive retinopathy. An experimental study in the monkey.

Retinal changes in accelerated hypertension were studied in seventeen monkeys with experimental hypertension by means of ophthalmoscopy and colour and flourescence photography during life, and by injection and digest preparations and light and electron microscopy after the animals had been killed. Cotton-wool spots developed in all but three monkeys. The arteries became tortuous and dilated and the light reflex decreased in those animals that became hypertensive. The earliest abnormality was a development of many points of fluorescein leakage on terminal arterioles or small arteries. Such leaking points were always present in relation to cotton-wool spots but were not confined to such areas. Focal narrowing of arteries was not observed but arteriolar occlusion and retrograde filling of the distal segment was present in three animals. Superficial linear haemorrhages were noted in five animals. Light microscopy revealed cotton-wool spots which were identical to those observed in man with a collection of swollen axons containing densely staining pseudonuclei. Study of the arterioles by electron microscopy showed findings ranging from normality to extensive necrosis. Many precapillary arteries were constricted and some were virtually occluded. Degenerative changes were present in smooth muscle cells in the wall of many of the constricted arterioles. Many arteries also showed insudation into their wall of plasma which had seeped into the muscular coat displacing and sometimes entirely replacing the smooth muscle cells. Except for arterioles with advanced necrosis, there was no indication of how plasma insudation occurred. Two arterioles with extensive necrosis showed a break within the endothelial cell cytoplasm through which penetration of plasma proteins had probably occurred. The extravascular tissues showed collections of amorphous material, sone of it with the typical banded configuration of fibrin. The sequence of events proposed to explain these features is as follows: (1) The arterioles constrict as the pressure rises, most likely as a result of vascular autoregulation. This may head to occlusion of the precapillary arterioles and is associated with necrosis of vascular smooth muscle. (2) Dilatation then occurs with insudation of plasma into the unsupported wall through a damaged endothelium. This stage probably corresponds to the autoregulatory break-point and is evidenced clinically by focal leakage of fluorescein. (3) Progressive plasma insudation into the vessel wall with further muscle necrosis results in secondary occlusion and the typical picture of advanced fibrinoid necrosis.

Animals↗