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Biomedical subjects

V Srinivasan

Publications and source records attributed to V Srinivasan.

At least 19 recordsLinked to original sources
PubMed1995

Day-case septal surgery under general anaesthesia and local anaesthesia with sedation.

Septal surgery (submucous resection and septoplasty) has been performed as a day-case procedure routinely under general anaesthesia and local anaesthesia with sedation at the Ipswich Hospital since 1992. The outcome of the day-case septal surgery over a period of 18 months has been audited. A total of 95 cases were operated on of which 48 were under general anaesthesia (GA) and 47 under local anaesthesia (LA) with sedation using midazolam intravenously. The bleeding rate and overnight admission rate were 10.5 and 11.4 per cent respectively. The bleeding rate was the same in both GA and LA groups. The combination of local anaesthesia and sedation has been found to be safe, effective and acceptable to patients. It is concluded that septal surgery is suitable as a day procedure and that local anaesthesia combined with sedation has a definite place if carried out properly.

Adolescent↗
PubMed1994

Quantitative in vivo iontophoretic studies.

An experimental methodology was developed to evaluate the physicochemical basis for in vitro-in vivo correlations in iontophoretic delivery situations. This experimental methodology can be used to quantitatively evaluate the extent of interaction between chemical permeation enhancers and iontophoresis for drug delivery. The inherent advantages of using Ag/AgCl electrodes are fully exploited to control pH and minimize depletion of permeant during prolonged periods of iontophoresis.

Animals↗
PubMed1994

Massive intraperitoneal hemorrhage associated with renal pathology.

We report on 2 patients who presented with massive intraperitoneal hemorrhage. In spontaneous renal hemorrhage there is often an underlying pathological condition, usually renal carcinoma. The investigation of choice is computerized tomography, while arteriography is reserved for cases in which no renal mass is found. Nephrectomy may be life-saving but conservative treatment is an acceptable alternative when the underlying pathological condition is benign and the patient is in stable condition.

Aged↗
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↗
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↗
PubMed1990

Iontophoresis of polypeptides: effect of ethanol pretreatment of human skin.

This paper explores the possibility of iontophoretically enhancing the in vitro transdermal flux of two polypeptides: leuprolide (a LHRH analogue; MW = 1209.4) and a cholecystokinin-8 analogue (CCK-8; MW = 1150.17). Control experiments at an applied voltage of 0.5 V across full-thickness human skin did not yield measurable fluxes of either polypeptide, suggesting that despite the expected iontophoretic flux enhancements, the intrinsic permeability of these polypeptides through skin may be too low to allow significant amounts of the drug to permeate. Therefore, pretreatment with ethanol (to simulate the effect of a chemical permeation enhancer) followed by iontophoresis was investigated with the aim of evaluating the potential of the enhancer plus ionophoresis as a means for controlled transdermal delivery of these polypeptides. The ethanol pretreatment dramatically increased the passive fluxes of both polypeptides, and iontophoresis produced further enhancements in their fluxes. Also, the experimental enhancement factors for leuprolide as a function of the applied voltage appeared to be generally lower than the predictions of the constant field theory. A synergism of iontophoresis with a chemical permeation enhancer may be a potential route for controlled transdermal delivery of these and other high molecular weight polypeptides.

Ethanol↗
PubMed1990

Cationic antiprotozoal drugs. Trypanocidal activity of 2-(4'-formylphenyl)imidazo[1,2-a]pyridinium guanylhydrazones and related derivatives of quaternary heteroaromatic compounds.

A series of quaternary 2-phenylimidazo[1,2-a]pyridinum salts has been prepared and evaluated for antiparasitic activity. Primary attention was focused on derivatives with amido, substituted hydrazone, and heterocyclic functionality at the para position of the phenyl substituent. Guanylhydrazones and N-substituted guanylhydrazones of the 4'-formyl-substituted compounds are very active against the blood state Trypanosoma rhodesiense in mice by subcutaneous or oral administration. The most potent compounds attain 100% survival for 30 days at doses of less than 1.0 mg/kg (sc) and greater than 5.0 mg/kg (po). Weaker activity is noted for certain other 4'-substituents such as carboxamidines and carboxamide oximes. Considerable variation in structure, including replacing of the imidazo [1,2-a]pyridinium ring by other cationic heterocyclic rings and insertion of linking groups between the heterocyclic ring and phenyl group, can be done, and a high level of activity is maintained. Relationships between these structural changes and biological activity are discussed.

Animals↗
PubMed1990

Sodium azide as a preservative in epidemiological studies of helminth ova in fecal specimens.

In 20 fecal specimens stored at ambient temperature (30-40 degrees C) for 3-7 days, substantial reductions in hookworm ova load were observed when a sensitive egg counting method (modified Kato's technique) was employed. Aliquots to which sodium azide (3 mg/g of fecal matter) was added showed considerably less reduction. A larger study on 120 specimens confirmed that there was no reduction up to 3 days. Significant decreases, however, occurred by 5 days, and these could not be prevented even by doubling the sodium azide dose (to 6 mg). It is recommended that in epidemiological studies of hookworm infestation in tropical countries, 3 mg of sodium azide should be added per g of fecal matter within 6 h of collection and the specimen tested within 3 days.

Adolescent↗
PubMed1989

Transdermal iontophoretic drug delivery: mechanistic analysis and application to polypeptide delivery.

Three factors are of primary importance in determining the iontophoretic flux of a charged solute: the electrochemical potential gradient across the skin, an increase in skin permeability to passive transport due to iontophoresis (loosely defined as skin damage), and a current-induced water flux. The latter two factors can also affect the transport of uncharged solutes during iontophoresis. A method of correcting for the skin damage effect is introduced. The contributions of the water transport effect relative to that of the applied voltage drop for charged solutes is estimated. It is shown that the water transport contribution is generally lower than the contribution due to the applied voltage drop. The observed iontophonetic flux of the enhancement factors due to the applied voltage drop alone are compared with the theoretical predictions based on the constant field assumption. It is shown that the theoretical predictions are higher than the experimental observations. This work also examines, for the first time, a synergism of iontophoresis and pretreatment with a chemical penetration enhancer as a means for delivering high molecular weight polypeptides. It is shown that a 2-h pretreatment with absolute ethanol followed by iontophoresis dramatically increases the permeability coefficient of insulin through human skin.

Administration, Cutaneous↗
PubMed1989

Peer review among district health officers in Maharashtra, India.

A management information system in Maharashtra State, India, was used to obtain primary health care performance data for review at monthly meetings of peers, including District Health Officers, Auxiliary Nurse Midwives and Multipurpose Workers. The meetings were conducted in a problem solving, educational atmosphere. The effect of this process was marked improvement in health worker motivation and performance.

Community Health Services↗
PubMed1989

Psychoactive drugs, pineal gland and affective disorders.

The possibility of pineal gland involvement as a part of "neuroendocrine dysfunction" in some of the psychiatric diseases has received special attention in recent years. The discovery of a cascade of receptors and the action of many psychoactive drugs on pineal gland supports the concept that the pineal gland can be considered as a suitable model system for assessing the action of psychotropic drugs. Psychotropic drugs, particularly antidepressants both tricyclics and monoamine oxidase inhibitors when administered either to animals or to patients suffering from depressive illness affects the pineal gland function and melatonin concentration. This raises the possibility that the beneficial effects of these drugs may relate to their ability to alter the pineal gland function and melatonin secretion. The occurrence of seasonal affective disorders and their response to bright light treatment implicate, melatonin as a "bio-chemical marker" for these disease states. In view of these facts it can be suggested that pineal gland does play an important role in the etiology of mental diseases, especially affective disorders.

Animals↗