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Biomedical subjects

V Srinivasan

Publications and source records attributed to V Srinivasan.

At least 91 records · Page 5Linked to original sources
PubMed1994

A comparison of two radiotherapy regimens for the treatment of symptoms from advanced bladder cancer.

Pain and haematuria are two of the most distressing symptoms in patients with advanced bladder cancer. The aim of palliative radiotherapy is to relieve these symptoms with the minimum of stress to the patient and with minimal side effects. Two treatment regimens were studied: hypofractionated radiotherapy giving 1700 cGy in two fractions over 3 days and conventional palliative radiotherapy giving 4500 cGy in 12 fractions over 26 days. This study assesses 41 patients, all with Grade II-III T3-4 transitional cell carcinomas of the bladder treated between 1982 and 1989, presenting with haematuria and local pain. Two-fraction (hypofractionated) treatment was given to 22 patients and conventional palliative radiotherapy to 19; patients were selected by performance status. The effect on haematuria was assessed as cleared, intermittent or persistent. Pain was assessed by noting reduction in the need for opiate analgesia. Any side effect was recorded. In the patients receiving two-fraction radiotherapy, 59% had clearance of the haematuria and in 73% there was improvement of their pain, compared with 16% and 37% respectively in those receiving conventional palliation. Survival of the two groups was 9.77 months and 14.47 months respectively. Side effects were trivial in both regimens. Radiotherapy given in two fractions for patients in poor general health is well tolerated and less distressing than the standard palliative regimen with 12 fractions. Haematuria and pain were more effectively palliated than with conventional treatment, though survival was shorter. We conclude that hypofractionated radiotherapy may be the palliative treatment of choice and the study supports the need for a prospective assessment of this treatment approach.

Aged↗
PubMed1993

Soft drugs--XIV. Synthesis and anticholinergic activity of soft phenylsuccinic analogs of methatropine.

Three soft drug analogs and a metabolite of methatropine based on phenylsuccinic structural moiety were synthesized and tested for activity. In an in vivo assay, the soft drugs were found to be two orders of magnitude less potent than methatropine while the carboxylate metabolite was found to be one order of magnitude less potent than the soft drugs. A structural isomer of compound 4a was found to be less potent. All the soft drugs tested elicited shorter durations of mydriatic action in rabbit eyes compared to atropine. The untreated eye was dilated in the atropine treated animals while no dilation occurred in the soft drug treated animals indicating facile systemic metabolism of the soft drugs to inactive moieties, possibly the carboxylate metabolite. In in vitro stability studies, the soft drugs have been found to be more hydrolytically labile than atropine. The shorter duration of mydriatic action of compound 4a coupled with increased hydrolytic lability make this a candidate for further study.

Animals↗
PubMed1993

Eye protection in ear, nose and throat surgery.

The aim of this study was to quantify the risk of blood splashes to the conjunctiva during ear, nose and throat surgery. Two hundred and sixty consecutive operations by three surgeons were assessed for contamination of safety glasses and other factors. We found that 15 per cent of operations resulted in blood droplet contamination of safety glasses. In 92 per cent of these, contaminations were on the exterior of the glasses and eight per cent were on both sides. We concluded that about one and a half per cent of operations would result in droplet contamination of the conjunctiva and that safety spectacles reduced the risk by a factor of about 10. This study generally concurs with that of previous research in the areas of general and orthopaedic surgery and necropsies. We substantiate the need for eye protection for all ear, nose and throat procedures. Spectacles do provide a reasonable degree of protection but where absolute protection is needed i.e. in high risk groups, goggles should be used in preference to safety spectacles.

Blood-Borne Pathogens↗
PubMed1992

Radioprotection by metals: selenium.

The need exists for compounds that will protect individuals from high-dose acute radiation exposure in space and the agents that might be less protective but less toxic and longer acting. Metals and metal derivatives provide a small degree of radioprotection (dose reduction factor < or = 1.2 for animal survival after whole-body irradiation). Emphasis is placed here on the radioprotective potential of selenium (Se). Both the inorganic salt, sodium selenite, and the organic Se compound, selenomethionine, enhance the survival of irradiated mice (60Co, 0.2 Gy/min) when injected IP either before (-24 hr and -1 hr) or shortly after (+15 min) radiation exposure. When administered at equitoxic doses (one-fourth LD10; selenomethionine = 4.0 mg/kg Se, sodium selenite = 0.8 mg/kg Se), both drugs enhanced the 30-day survival of mice irradiated at 9 Gy. Survival after 10-Gy exposure was significantly increased only after selenomethionine treatment. An advantage of selenomethionine is lower lethal and behavioral toxicity (locomotor activity depression) compared to sodium selenite, when they are administered at equivalent doses of Se. Sodium selenite administered in combination with WR-2721, S-2-(3-aminopropylamino)ethylphosphorothioic acid, enhances the radioprotective effect and reduces the lethal toxicity, but not the behavioral toxicity, of WR-2721. Other studies on radioprotection and protection against chemical carcinogens by different forms of Se are reviewed. As additional animal data and results from human chemoprevention trials become available, consideration also can be given to prolonged administration of Se compounds for protection against long-term radiation effects in space.

Aerospace Medicine↗
PubMed1992

Radioprotection by vitamin E: injectable vitamin E administered alone or with WR-3689 enhances survival of irradiated mice.

Radioprotection by injectable vitamin E (alpha-tocopherol) was investigated in mice exposed to 60Co radiation (0.2 Gy/min). Vitamin E injected subcutaneously either 1 hr before or within 15 min after irradiation significantly increased 30-day postirradiation survival in CD2F1 male mice. A dose reduction factor (DRF) of 1.11 (95% confidence interval [1.08, 1.14]) was observed for vitamin E at a dose of 100 IU/kg body weight administered within 15 min after irradiation. Combination studies with the phosphorothioate WR-3689 (S-2([3-methylaminopropyl]amino)ethylphosphorothioic acid) were undertaken to determine whether radioprotection by WR-3689 could be enhanced by vitamin E. Mice were given WR-3689 (150-225 mg/kg, intraperitoneally) 30 min before irradiation and were given vitamin E (100 IU/kg) either 1 hr before or within 15 min after irradiation. Survival was significantly increased in mice given vitamin E and WR-3689 before irradiation as compared to mice given WR-3689 alone: the DRF for WR-3689 (150 mg) was 1.35 [1.32, 1.38]; for WR-3689 combined with vitamin E (100 IU), the DRF was 1.49 [1.45, 1.53].

Amifostine↗
PubMed1992

Skin alteration and convective solvent flow effects during iontophoresis. II. Monovalent anion and cation transport across human skin.

Total flux enhancement of ions during iontophoresis is due primarily to the electrochemical potential gradient. However, secondary effects such as convective solvent flow and, in biological membranes, permeability increases as a result of applied field may also contribute to flux enhancement. The modified Nernst-Planck theory includes a solvent flow velocity term and predicts that the flux of uncharged molecules is enhanced or retarded depending on the polarity of the applied field. Polarity-dependent solvent flow velocity, as measured by the flux enhancement of mannitol, has been demonstrated in human epidermal membrane during iontophoresis. In the present study, the solvent flow velocity effects on the flux enhancement of a model cation (tetraethylammonium ion) and a model anion (salicylate ion) across human epidermal membrane were examined. The contribution of membrane alterations, due to the applied field, on overall ion flux was also considered. Solvent flow was found to have a small effect on the flux enhancement of both ions. However, membrane alterations were found to increase greatly the flux of the ionic species. Alterations in the epidermal membrane occurred at the highest voltage investigated (1000 mV) and appeared to reverse over time as indicated by the current and transport data.

Anions↗
PubMed1992

Extracorporeal shock wave lithotripsy for radiolucent stones.

Eleven patients with radiolucent urinary calculi were treated with shock wave lithotripsy. Nine of these patients experienced successful fragmentation of their stones and subsequent spontaneous passage of the calculi fragments. The majority of the stones were composed of uric acid alone or a mixture of uric acid and calcium oxalate. One stone with metabolites of triamterene also fragmented well. Uric acid calculi can be treated successfully with shock wave lithotripsy using adequate visualization by contrast injection.

Adult↗