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Biomedical subjects

S Seth

Publications and source records attributed to S Seth.

At least 19 recordsLinked to original sources
PubMed1992

Evidence for verapamil-induced functional inhibition of noradrenergic neurotransmission in vivo.

Contractions of the cat nictitating membrane have been used to explore the effects of calcium channel blockers on neurotransmission in vivo, by comparing the effects of verapamil and nifedipine on contractions of nictitating membrane following either electrical stimulation of the superior cervical ganglion or intravenous injection of the alpha-adrenoceptor agonist phenylephrine. Verapamil (0.3, 0.6 and 1.2 mg/kg, iv) produced a dose related and reversible inhibition of stimulation induced contractions but did not affect phenylephrine responses of nictitating membrane. Intravenous nifedipine (10, 20 and 40 micrograms/kg) produced inconsistent effects on both stimulation- and phenylephrine-induced contractions of the nictitating membrane. Thus only verapamil appears to selectively affect noradrenergic neurotransmission in this model, possibly by altering the neurotransmitter release from the terminals innervating the nictitating membrane in the cat.

Adrenergic Fibers↗
PubMed1992

Gastrointestinal endoscope disinfection practices in India: results of a national survey.

A questionnaire was sent to 435 endoscopy centers in the country to obtain information regarding current endoscopic disinfection practices. Of these, 133 (30.6%) centers responded. Adequate disinfection (a minimum exposure to 1% glutaraldehyde for 2 minutes) before the start of endoscopy sessions and between procedures was practised in 61 (46%) and 45 (34%) centers respectively. The proportion of centers practising adequate disinfection was similar among those performing < 1500 and > 1500 endoscopies/year (50% vs 36%; p = ns). Twenty two (17%) centers used some additional precautions in patients with hepatitis B virus infection or immunocompromised states. Two (1.5%) of the 133 centers performing upper GI endoscopies and eight (18%) of the 44 centers performing ERCP examinations reported occurrence of infections following these procedures. Allergic reactions to disinfectants were reported by five (4%) centers. We conclude that only about a third of the gastroenterology centers in the country are practising adequate endoscope disinfection routinely.

Cross Infection↗
PubMed1992

Prevalence of malaria in Ao Nagas and its association with G6PD and HbE.

Glucose-6-phosphate dehydrogenase (G6PD) and hemoglobin E (HbE) were studied among 708 malarial patients and control groups of Ao Nagas from the Mokokchung District of Nagaland in the extreme northeast of India. The data suggest that malaria is an important ecologic factor in maintaining the high frequency of G6PD deficiency and HbE among the Ao Nagas. Although migrations from adjoining populations that have a high frequency of both these traits could have contributed to the presence of these genes in the Ao Nagas, malaria also could be an essential determinant in maintaining the current high frequency in present-day Ao Nagas.

Ethnicity↗
PubMed1991

Case report: unusual CT appearances in a case of Budd-Chiari syndrome.

We describe a case of Budd-Chiari Syndrome due to hepatic venous blockage in which there were multiple space-occupying lesions on CT simulating tumour deposits. Ultrasound directed liver biopsy and laparoscopy proved these to be areas of haemorrhagic necrosis consistent with Budd-Chiari Syndrome without any evidence of malignancy. The CT finding of multiple large focal non-enhancing areas in liver does not always indicate tumour deposits in a patient suspected to have Budd-Chiari Syndrome.

Adult↗
PubMed1991

Duffy blood groups and malaria in the Ao Nagas in Nagaland, India.

Blood samples from 324 malarial patients and 384 healthy individuals belonging to the Ao tribal community have been examined for Duffy blood group systems. The complete absence of Duffy-negative individuals among the Ao Nagas suggests that selection for resistance to vivax malaria by means of the Duffy-negative phenotype has not been available in the southeast Asian regions including the Ao Nagas.

Duffy Blood-Group System↗
PubMed1991

Stability of dobutamine hydrochloride in peritoneal dialysis solutions.

The stability of dobutamine hydrochloride in peritoneal dialysis solutions at 4, 26, and 37 degrees C was determined. Dobutamine (as the hydrochloride salt) was added to dialysis solutions containing 1.5% or 4.25% dextrose to concentrations of 2.5, 5.0, and 7.5 mg/mL. Samples were stored at 4, 26, and 37 degrees C to mimic refrigerator, room, and body temperature, respectively. At 0, 4, 8, and 24 hours, the samples were analyzed in triplicate by stability-indicating high-performance liquid chromatography to determine the percentage of drug remaining. More than 90% of the drug was retained under all storage conditions in 1.5% dextrose dialysate containing an initial dobutamine hydrochloride concentration of 5.0 or 7.5 micrograms/mL. The mean concentration in the samples containing an initial dobutamine hydrochloride concentration of 2.5 micrograms/mL and stored at room temperature remained greater than 90% of the initial concentration for the first four hours and then decreased to less than 90%. Dobutamine was stable in 4.25% dextrose dialysate regardless of the initial concentration or the storage condition. Dobutamine hydrochloride 5.0 and 7.5 micrograms/mL in 4.25% dextrose dialysis solution was stable under all the test conditions. Dobutamine hydrochloride 2.5 micrograms/mL was stable in 1.5% dextrose dialysate for only four hours at room temperature.

Dialysis Solutions↗
PubMed1990

Opioid and non-opioid central cardiovascular effects of ketamine.

The cardiovascular responses to ketamine injected intracisternally were examined in chloralose anaesthetized cats. Blood pressure and heart rate were recorded at different time intervals after intracisternal injection of drug or saline vehicle. The low doses of ketamine (0.5 or 1.0 mg) elicited dose dependent increase in blood pressure and heart rate. In contrast the high dose of ketamine (4 mg), produced a fall in blood pressure and heart rate. The cardiovascular response elicited by the low dose was naloxone insensitive and completely blocked by haloperidol, but not by dopamine antagonist pimozide. The vasodepressor and bradycardiac effect of the 4 mg dose was naloxone antagonizable. These data show that excitatory cardiovascular effects of the low dose result from a naloxone resistant site while in high doses an inhibitory effect is elicited by action at naloxone sensitive opiate receptors.

Animals↗
PubMed1989

Degeneration and graft-induced restoration of dopamine innervation in the weaver mouse neostriatum: a quantitative radioautographic study of [3H]dopamine uptake.

A recently introduced quantitative radioautographic technique was used to characterize the striatal dopaminergic deficit in weaver mutant mice and to evaluate the extent of DA reinnervation resulting from cell suspension grafts of fetal ventral mesencephalic tissue. Brain slices from normal mice and unilaterally grafted weaver mice were incubated in [3H]DA, in the presence of desipramine and pargyline 3-5 months after graft surgery. Semi-thin sections from the fixed and resinembedded slices were subsequently exposed on tritium sensitive film and afterwards dipped in nuclear emulsion for light microscope radioautography. Alternative slices were embedded in Epon for post-embedding tyrosine hydroxylase (TH) immunocytochemistry. The grain density of the film radioautographs matched well the distribution of TH positive fibers. Both methods revealed an almost complete absence of DA axons in the dorsomedial quadrant of the weaver neostriatum and an increasing density of DA innervation towards the ventrolateral areas. In the light microscope radioautographs, only the ventral striatum (i.e. nucleus accumbens and olfactory tubercle) and a narrow ventral and periventricular zone of the caudate-putamen were covered by silver grain clusters typical of DA varicosity labeling. Such labeled varicosities were nevertheless found in reduced numbers the lateral portion of both nucleus accumbens and the olfactory tubercle. The remaining neostriatum was overlaid by diffuse silver grains. suggesting a deficient DA uptake and storage mechanism in the residual DA fibers in this region. Immunocytochemistry using antibodies specific for DA or TH provided further evidence that the residual DA innervation in the weaver neostriatum was biochemically defective. Weaver mice with grafts of ventral mesencephalic tissue in the right neostriatum showed an amphetamine-induced rotational bias to the contralateral side, which was not seen in the sham-operated animals. In contrast to the intrinsic weaver neostriatal DA innervation, DA fibers of graft origin exhibited the normal, clustered type of varicosity labeling. The computerized image analysis of silver grain density in film radioautographs was calibrated by counting these labeled varicosities in selected areas of light microscope radioautographs from the same sections. Results showed a mean DA reinnervation of neostriatal tissue surrounding the graft of about 20%, in some cases up to 80%, of the density seen in wild type mice, with a gradual decrease with distance up to 1-1.4 mm from the graft. The ventral parts of the neostriatum, which contained higher numbers of residual intrinsic DA fibers, were much more sparsely reinnervated than the dorsal and dorsomedial areas.(ABSTRACT TRUNCATED AT 400 WORDS)

Amphetamines↗
PubMed1989

X-chromosomal DNA polymorphisms in two ethnic groups from India.

Four polymorphic sites of the short arm of the X chromosome were studied in two racial groups from India, the Assamese and the Malayalee. Since the allelic frequencies of the two groups did not differ markedly from each other, the data from the two populations were pooled. The frequency of the A2 allele was 0.57 for the L1.28 probe, 0.20 for the RC8 probe, 0.28 for the pD2 probe and 0.11 for the L754 probe. The A3 allelic fragment of the RC8 probe was not found among 67 Indians, and in one Assamese woman an additional 7.0-kilobase fragment was found. The differences between the Indian population and other ethnic groups were analyzed.

Alleles↗
PubMed1987

Albumin concentration in human amniotic fluid from normal pregnancies.

The present study is an attempt to estimate the albumin concentration in the human amniotic fluid of normal pregnancy. The study has been conducted from 12th to 20th week and from 30th to 43rd weeks of gestation. The results revealed a characteristic gestational profile with an increase in the concentration with the advancement of pregnancy from the 12th till the 20th week and an inverse relationship between the albumin level and the gestational age after the 30th week till term. The relationship between the albumin levels and the order of pregnancy indicated that the albumin concentration was not influenced by the birth order.

Albumins↗