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Biomedical subjects

S Desai

Publications and source records attributed to S Desai.

At least 127 records · Page 7Linked to original sources
PubMed1995

Fibrosing necrotic nodule of the liver.

A fibrosing necrotic nodule of the liver is described in a 35 year old man suffering from malaria. This non-tumorous lesion is considered to be an entity of diverse pathogenesis.

Adult↗
PubMed1995

Impact of an intervention on HIV, sexually transmitted diseases, and condom use among sex workers in Bombay, India.

OBJECTIVE: To develop and test an HIV intervention targeting sex workers and madams in the brothels of Bombay. SUBJECTS AND METHODS: In a controlled intervention trial, with measurements before and after the intervention, 334 sex workers and 20 madams were recruited from an intervention site, and 207 and 17, respectively, from a similar control site, both in red-light areas of Bombay. All sex workers were tested for antibodies to HIV and syphilis, and for hepatitis B surface antigen. Information on sexual practices, condom use and knowledge of HIV was collected by interviewer-administered questionnaire. All subjects in the intervention group underwent a 6-month program of educational videos, small group discussions and pictorial educational materials; free condoms were also distributed. The blood tests and the questionnaire were readministered to all subjects at both sites immediately after the intervention. Both groups were followed for approximately 1 year. RESULTS: The baseline level of knowledge about HIV and experience with condoms was extremely low among both sex workers and madams. The baseline prevalence of HIV antibodies was 47% in the intervention group and 41% in the control group (P = 0.17). The incidence densities for HIV and sexually transmitted diseases were significantly different in the two groups (all P < 0.005): 0.05 and 0.16 per person-year of follow-up for HIV, 0.08 and 0.22 per person-year for antibodies to syphilis, and 0.04 and 0.12 per person-year for hepatitis B surface antigen in the intervention and control women, respectively. Following the intervention, women reported increased levels of condom use, and some (41%) said they were willing to refuse clients who wouldn't use them. However, both the sex workers and the madams were concerned about losing business if condom use was insisted upon. CONCLUSIONS: Both HIV prevalence and incidence are alarmingly high among female sex workers in Bombay. Successful interventions can be developed for these women, and even a partial increase in condom use may decrease the transmission of HIV and sexually transmitted diseases. Intervention programs of longer duration that target madams and clients and make condoms easily available are urgently needed at multiple sites in red-light areas.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Clinicopathological evaluation of metastatic carcinomas of bone : a retrospective analysis of 114 cases over 10 years.

This is a clinicopathological study of 114 cases of metastatic carcinomas of bone accessioned between 1979 and 1988 at a large cancer hospital. The cases were divided into two groups. The first group comprised of 68 cases (59.64 percent), which included those where the primary was either known (Ia-12 cases), detected after simple investigations (Ib - 18 cases) or detected after extensive investigations (Ic - 38 cases). The lung emerged as the primary source of the metastases in almost half the cases. Hence an X-ray chest should be the basic essential investigation in the workup of skeletal metastasis. The second group comprised of 46 cases (40.35 percent), where the primary remained unknown; 56.5 percent of these were adenocarcinomas. When the histological diagnosis is adenocarcinoma in cases of an occult primary, it is often difficult to pinpoint the primary site after exclusion of organs like breast, prostate, thyroid and kidney.

Adenocarcinoma↗
PubMed1994

HIV-1 TAR RNA has an intrinsic ability to activate interferon-inducible enzymes.

The TAR sequence at the 5'-termini of all HIV-1 mRNA species forms a stable structure that is responsible for both transcriptional and translational regulation of HIV-1. Previously we and others reported that purified TAR RNA synthesized by in vitro transcription could activate two interferon-induced enzymes, the protein kinase (PKR) and 2-5A-synthetase. Because the PKR- and 2-5A-systems block protein synthesis initiation and induce RNA decay, respectively, these findings suggested mechanisms for the control of HIV-1 replication by the interferon system. To determine if contaminating dsRNA from in vitro transcription reactions was responsible for this effect, as suggested by Gunnery et al. 1990, (Proc., Natl. Acad. Sci. USA 87, 8687), we have reexamined these findings using chemically synthesized TAR (nucleotides +1 to +57). TAR RNA is shown here to have an intrinsic ability to activate PKR and 2-5A-synthetase. In contrast, a mutant form of TAR designed to have a disrupted secondary structure did not stimulate either enzyme. Chemically synthesized TAR mimicked other dsRNA species in its ability to activate and inhibit PKR at low and high RNA concentrations, respectively. HIV-1 TAT protein inhibited activation of PKR by HIV-1 TAR RNA suggesting an escape mechanism for the virus.

2',5'-Oligoadenylate Synthetase↗
PubMed1994

Ionization and adsorption of a series of local anesthetics in detergent micelles: studies of drug fluorescence.

The goal of this study was to compare the behavior of structurally homologous local anesthetics (LAs) adsorbed to a simplified membrane model. Interactions of LAs with micelles made from negative and neutral detergents were assayed by drug fluorescence. Micellar:drug affinity, equivalent dielectric constant and pKa of bound LAs were assessed for procaine, tetracaine, procainamide, benzocaine and aminoparabenzyldiethylamine, a procaine homologue containing an alkyl chain instead of an ester bond. Shifts in maximum emission wavelength and changes in fluorescence intensity showed that 1) increased LA hydrophobicity (expressed as octanol:buffer partition coefficient) corresponded to increased affinity for all micelles; 2) protonated species of LA were bound more tightly than neutral species to negative micelles, but less tightly to unchanged micelles; 3) drugs with larger dipole moments (amide < ester < alkyl) bind less tightly to micelles than those with smaller dipoles; 4) Larger dipole moments of LAs also result in a larger equivalent dielectric constant around the micellar-bound LAs, meaning that the LA binds at a shallower depth from the micelle surface; and 5) binding the neutral micelles lowers the pKa but binding to negatively charged micelles raises the pKa (due to the concentrating effects of surface charge on H+). The results provide a picture of interfacial adsorption of LAs in a relatively simple system that should allow interrelation of the dipole field contributions to LA behavior in phospholipid bilayers.

Adsorption↗
PubMed1993

A practical approach to crosslinking.

The various aspects of chemical crosslinking are addressed. Crosslinker reactivity, specificity, spacer arm length and solubility characteristics are detailed. Considerations for choosing one of these crosslinkers for a particular application are given as well as reaction conditions and practical tips for use of each category of crosslinkers.

Amines↗
PubMed1993

Ocular pharmacokinetics of tobramycin. A comparative radioimmunoassay and microbiological assay.

The ocular pharmacokinetics of tobramycin were studied in human and rabbit eyes following topical and subconjunctival administration in humans and following intravitreal administration in rabbit eyes. Each aqueous and vitreous sample was analysed by radioimmunoassay and microbiological assay. Topical instillation of 0.3% eyedrops by a loading dose schedule provided rapid penetration of the drug into the aqueous humour with a peak titre of 3.24 mg/l (RIA) at 2-hour intervals and therapeutic levels up to 6 hours. A subconjunctivally administered standard dose of 20 mg/0.5 ml of the drug also showed rapid penetration in therapeutically effective concentration with a peak titre of 22.34 mg/l (RIA) and 16.80 mg/l (MBA) at 2-hour intervals and therapeutic levels of the drug remained up to 20 hours later. A study of vitreous clearance following the administration of a single intravitreal injection in rabbit eyes showed bioavailability of the drug at therapeutically effective levels for more than 72 hours. Mostly two, but sometimes only one sample at each time interval, were studied. Radioimmunoassay and microbiological assay results showed excellent correlation, with correlation coefficient > 0.90 at 1.0% level of probability.

Adult↗
PubMed1993

A floating controlled-release drug delivery system: in vitro-in vivo evaluation.

A novel floating controlled-release drug delivery system was formulated in an effort increase the gastric retention time of the dosage form and to control drug release. The buoyancy was attributed to air and oil entrapped in the agar gel network. A floating controlled-release 300-mg theophylline tablet having a density of 0.67 was prepared and compared in vitro and in vivo to Theo-dur. The in vitro release rate of the floating tablet was slower. In vivo scintigraphic studies for a floating and a heavy nonfloating tablet, under fasting and nonfasting conditions, showed that the presence of food significantly increased the gastric retention time for both tablets, and tablet density did not appear to make a difference in the gastric retention time. However, the positions of the floating and nonfloating tablets in the stomach were very different. Bioavailability studies in human volunteers under both fasting and nonfasting conditions showed results comparable to those with Theo-dur. The floating controlled-release theophylline tablet maintained constant theophylline levels of about 2 mg/mL for 24 hr, which may be attributable to the release from the agar gel matrix and the buoyancy of the tablet in the stomach.

Biological Availability↗
PubMed1993

Postpartum hemorrhage producing acute ischemic optic neuropathy.

A rare case of bilateral peripartum blindness due to acute ischemic optic neuropathy (AION) occurring after an episode of postpartum hemorrhage is described. Massive blood loss and the resultant hypotension was instrumental in reducing the perfusion pressure at the optic nerve head and producing ischemic damage to it.

Acute Disease↗
PubMed1993

Developmental trends in the interaction between auditory and linguistic processing.

The developmental course of multidimensional speech processing was examined in 80 children between 3 and 6 years of age and in 60 adults between 20 and 86 years of age. Processing interactions were assessed with a speeded classification task (Garner, 1974a), which required the subjects to attend selectively to the voice dimension while ignoring the linguistic dimension, and vice versa. The children and adults exhibited both similarities and differences in the patterns of processing dependencies. For all ages, performance for each dimension was slower in the presence of variation in the irrelevant dimension; irrelevant variation in the voice dimension disrupted performance more than irrelevant variation in the linguistic dimension. Trends in the degree of interference, on the other hand, showed significant differences between dimensions as a function of age. Whereas the degree of interference for the voice-dimension-relevant did not show significant age-related change, the degree of interference for the word-dimension-relevant declined significantly with age in a linear as well as a quadratic manner. A major age-related change in the relation between dimensions was that word processing, relative to voice-gender processing, required significantly more time in the children than in the adults. Overall, the developmental course characterizing multidimensional speech processing evidenced more pronounced change when the linguistic dimension, rather than the voice dimension, was relevant.

Adult↗
PubMed1992

Xerophthalmia clinics in rural eye camps.

Even though the primary prevention of many eye diseases can be effectively incorporated into the existing pattern of rural eye camps, efforts in this direction are restrained and insubstantial. We describe our technique and experience in the prevention of xerophthalmia by organising a distinct entity called a xerophthalmia clinic in our eye camps. The clinic consists of an Ophthalmologist or an Ophthalmic assistant who will exclusively examine children who come to the eye camp. This is perhaps, the first report on rural xerophthalmia clinics, in ophthalmic literature. Over a seven year period from 1984 to 1990 we have conducted 71 xerophthalmia clinics amongst the ninty eye camps organised. A total of 11,370 children were examined in the xerophthalmia clinic out of which 18.9% were afflicted with the disease. Therapeutic doses of Vitamin A were administered on the spot to the afflicted and prophylactic doses were administered to the rest. Intensive health education efforts are made through clinics to effectuate change in dietry habits towards consumption of locally grown DGLV (Dark Green Leafy Vegetables) like Anthenum, chenopodium and Amaranthus. A bipronged offensive consisting of mega-dosing and health education is, for the present and the foreseeable future, the best strategy to combat xerophthalmia in this desert region. A year by year breakdown of prevalence rates in the present study shows that in years of severe drought the prevalence of xerophthalmia increases three fold over the non-drought or mild drought years, thereby demonstrating that drought is a substantial risk factor in developing countries leading to vitamin A deficiency and xerophthalmia.

Child↗
PubMed1992

Aqueous kinetics of sisomicin sulphate.

Sisomicin sulphate is a new-generation aminoglycoside with a broad spectrum of antimicrobial activity that includes Pseudomonas aeruginosa. It is superior to gentamicin against indole-negative Proteus and some resistant strains of Pseudomonas. The ocular pharmacokinetics of sisomicin have not been explored. We used the agar diffusion technique of microbial assay to determine the aqueous penetration and bioavailability of a subconjunctivally placed standard dose of 20 mg/0.4 ml of sisomicin sulphate in 20 human volunteers undergoing elective cataract surgery. A peak concentration of 16.4 mg/l was found in the aqueous humour 78 minutes after injection, which is 65 times the minimum inhibitory concentration for Pseudomonas. The antibiotic was bioavailable up to 1203 minutes after injection in a concentration of 0.9 mg/l, which easily covers the minimum inhibitory concentration of Staphylococcus aureus and Pseudomonas. The antibiotic disappears from the aqueous humour at the 1434 minute interval (approximately 24 hours). The elimination half-life (t1/2 of sisomicin was determined to be 5.16 hours (K = 0.134/hour) and the aqueous clearance was 2.87 microliters/min.

Aqueous Humor↗