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Biomedical subjects

A K Ray

Publications and source records attributed to A K Ray.

At least 37 records · Page 2Linked to original sources
PubMed2000

Role of light in the mediation of acute effects of a single afternoon melatonin injection on steroidogenic activity of testis in the rat.

Young adult male rats, maintained either in an LD 12 : 12 or in continuous illumination (LL) for one week, were given a single injection of 25 microg melatonin/100 g body wt or ethanolic-saline (control) at 17.00 h. Animals from each group were sacrificed at 11.00 h on the following day. The activity of two important steroidogenic enzymes, 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) and delta(5)-3 beta-hydroxysteroid dehydrogenase (delta(5)-3 beta-HSD), and serum concentrations of testosterone, were measured following highly specific and sensitive spectrophotometric techniques and RIA, respectively. A significant decrease in the activity of both the steroidogenic enzymes was noted in the testes of melatonin-treated rats maintained under normal light-dark schedules, but this response was found to be lacking in the LL rats. However, no significant changes in the level of serum testosterone were noted in either group of melatonin-treated rats from the values in respective groups of ethanolic saline-administered LD and LL rats. Exposure of ethanolic saline-injected rats to continuous light also did not cause any change in the steroidogenic activity of the testis from those in LD rats. The study indicates that continuous light as such does not affect the endocrine function of testis but abolishes suppressive effects of melatonin on the steroidogenic activity of the testis in rat.

17-Hydroxysteroid Dehydrogenases↗
PubMed2000

Rise of intrasynaptosomal Ca2+ level and activation of nitric oxide synthase in adult rat cerebral cortex pretreated with 3-5-3'-L-triiodothyronine.

Accumulation of free, ionized calcium (Ca2+) and stimulation of nitric oxide synthase (NOS) activity in depolarization-induced synaptosomes prepared from adult rat cerebral cortex have been demonstrated after addition of various doses (0.1-1,000 nM) of 3,5,3'-L-triiodothyronine (T3). The effects of T3 doses on those parameters are found to occur in a dose-dependent manner. The T3 (100 nM)-induced optimum rise in intrasynaptosomal Ca2+ level [Ca2+]i seems to be an early event occurring within 5 s; whereas, the maximum stimulation of NOS activity is observed during 10 to 30 s of T3 (100 nM) administration, indicating a delayed effect. T3 has no such effects on those parameters in synaptosomes at nondepolarized condition. Although the rise in [Ca2+]i and stimulation of NOS activity after application of T3 seem to be sequential events, the present data indicate a definite role of T3 in nongenomic signal generation and transfer in mature rat cerebral cortex.

Animals↗
PubMed2000

NMR studies of structure and dynamics in fruit cuticle polyesters.

Cutin and suberin are support polymers involved in waterproofing the leaves and fruits of higher plants, regulating the flow of nutrients among various plant organs, and minimizing the deleterious impact of microbial pathogens. Despite the complexity and intractable nature of these plant biopolyesters, their molecular structure and development are amenable to study by suitable solid-state and solution-state NMR techniques. Interactions of tomato cutin with water were examined by solid-state 2H and 13C NMR, showing that water films enhance rapid segmental motions of the acyl chains and are associated with a fivefold increase in surface elasticity upon cutin hydration. The suberization of wounded potato tissues was studied by solid-state 13C NMR, revealing the likely phenylpropanoid structures that permit dense cross-linking of the suberin structure and their proximity to the cell-wall polysaccharides. Finally, two new approaches were developed to elucidate the molecular structures of these biopolymers: partial depolymerization followed by spectroscopic analysis of the soluble oligomers; and swelling of the intact materials followed by magic-angle spinning (MAS) NMR analysis.

Citrus↗
PubMed1998

Specific binding of L-triiodothyronine modulates Na(+)-K(+)-ATPase activity in adult rat cerebrocortical synaptosomes.

Interactions of L-triiodothyronine (T3) in adult rat cerebrocortical synaptosomes were studied in vitro. Scatchard plot analysis revealed two sets of T3 binding sites. The degree of saturation of T3 binding sites (putative receptor) correlated well with the dose-dependent inhibition of Na(+)-K(+)-ATPase activity in synaptosomes. The relative binding affinities and relative inhibition of enzyme activities for different TH analogues were L-T3 > T3-amine > TRIAC = L-T4 > r-T3 > T2 and L-T3 > T3-amine > TRIAC > L-T4 > r-T3 > T2, respectively. The present study demonstrates the nature of inhibition of synaptosomal Na(+)-K(+)-ATPase activity may be as a function of T3 occupancy of synaptosomal receptor sites in adult mammalian brain.

Animals↗
PubMed1998

The use of exfoliative cytology for the early diagnosis of oral cancers: is there a role for it in education and private practice?

BACKGROUND: Early detection of oral cancers is not easy, because oral precancerous lesions and early oral cancers can mimic many benign conditions in the mouth, leading to delays in diagnosis and treatment. There is a need to emphasize the early diagnosis of oral cancers in order to reduce the unacceptably high morbidity and mortality. METHODS: A survey regarding oral exfoliative cytology was completed by 132 dentists in Virginia who were randomly chosen from a mailing list. RESULTS: Less than half of the dentists (41.7%) had been taught how to obtain a cytologic smear, and only 26.0% knew the clinical indications for doing so. Only 9.2% of the dentists had ever obtained a cytologic smear in private practice. Of the 13 dentists in the survey who had done so, 12 had been trained in the technique. Interest in learning the cytologic technique and getting the needed supplies was indicated by 79.2% of the dentists. CONCLUSIONS: Diagnostic aids in the evaluation of oral mucosal lesions can serve an important role by identifying lesions that need to be biopsied in spite of a "benign" appearance. Exfoliative cytology, as well as vital staining, may aid in this goal. This has implications regarding undergraduate and postdoctoral education.

Cytodiagnosis↗
PubMed1996

Chronic exercise alters EEG power spectra in an animal model of depression.

The EEG from frontal cortex, EMG and EOG were recorded from rats exposed to only exercise (Treadmill), only stress, exercise + stress and neither (control). In comparison with the control group, the percent of Delta activity in the awake was significantly increased in the depressed group and significantly decreased in the exercised groups, while for Beta-2, the reverse occurred; Theta increased and Beta-2 decreased in the NREM sleep state of the depressed group and the opposite happened for the exercised groups. Delta and Alpha-2 activity significantly increased in the depressed group, and they were significantly decreased in the exercised groups whereas the Beta-2 activity showed contrary changes in the REM sleep state. These findings indicate that exercise has the opposite effect from what stress has on qEEG and concomitant physical exercise reduces the effects of stress. Behavioral tests were done by Open Field (OF) and High Plus Maze (HPM). Slow EEG activity (Delta, Theta, Alpha) was significantly positively correlated with immobilization in the OF and defecation in both OF and HPM and negatively with the food intake, transfer latency in HPM; rearing, grooming and total ambulation in OF Whereas, fast activity (Beta-2) was significantly negatively correlated with immobilization in OF and defecation in OF and HPM, while positively with ambulation in the central squares of OF and time spent at the central cross and number of times arms crossed in the HPM.

Animals↗
PubMed1995

A computational model for electron backscattering in electron dosimetry.

A one-dimensional electron transport algorithm based on the ideas of invariant imbedding has been developed and applied to the problem of electron backscattering in electron dosimetry. Results have been compared with experimental and Monte Carlo results. Agreement appears to be reasonable at low incident energies (0.5 to 10 MeV) and low Z(Z < or = 65) materials.

Electrons↗
PubMed1994

Synthesis of the globotetraose tetrasaccharide and terminal tri- and di-saccharide fragments.

The 2-(trimethylsilyl)ethyl (TMSEt) beta-glycosides of globotetraose [beta-D-GalNAc-(1-->3)-alpha-D-Gal-(1-->4)-beta-D-Gal-(1-->4)-D-Glc] and the terminal trisaccharide, as well as the methyl alpha-glycoside 1 of the terminal disaccharide, were synthesised by silver trifluoromethanesulfonate-promoted beta-glycosylation of suitably protected galactoside, galabioside, and globotrioside alcohols with 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-galactopyranosyl chloride, followed by removal of protecting groups. Removal of the anomeric TMSEt group of the globotetraoside and of the terminal trisaccharide, using trifluoroacetic acid-dichloromethane, gave the corresponding hemiacetal sugars 8 and 3. The TMSEt glycoside of the terminal trisaccharide was converted, via the 1-acetate, into the corresponding isobutyl (4) and 3-butylsulfonyl-2-[(butylsulfonyl)methyl]propyl (5) glycosides and into the TMSEt thioglycoside 6 via the glycosyl bromide.

Antigens↗
PubMed1994

Synthesis of the Forssman pentasaccharide and terminal tetra-, tri-, and di-saccharide fragments.

The 2-(trimethylsilyl)ethyl (TMSEt) beta-glycosides of the Forssman pentasaccharide [alpha-D-GalNAc-(1-->3)-beta-D-GalNAc-(1-->3)-alpha-D-Gal- (1-->4)-beta-D-Gal-(1-->4)-D-Glc] and the terminal tetrasaccharide, as well as the methyl glycosides 1 and 2 of the terminal di- and tri-saccharides, were synthesised by silver trifluoromethanesulfonate-promoted alpha-glycosylation of suitably protected mono-, di-, tri-, and tetrasaccharide alcohols with 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosyl bromide, followed by removal of protecting groups. The anomeric TMSEt group of the Forssman pentasaccharide and terminal tetrasaccharide was removed with trifluoroacetic acid-dichloromethane, to give the corresponding hemiacetal sugars 4 and 6.

Carbohydrate Sequence↗
PubMed1994

Synaptosomal T3 content in cerebral cortex of adult rat in different thyroidal states.

The quantitation of thyroid hormone levels in cerebrocortical synaptosomes of the adult rat at altered thyroid states was studied because of the recent idea of the involvement of thyroid hormone in the adult mammalian brain. In contrast to a marked fall in serum T3 levels in PTU-induced hypothyroid rats, the synaptosomal T3 content was raised by 9.5 fold in this hypothyroid situation compared to the euthyroid control rats. A single injection of T3 (2 micrograms/g) to the hypothyroid rats lowered the T3 level to about half of those values obtained in only hypothyroid condition. The T4 levels remained below the detectable range in all the groups tested. This may be because 70% to 80% of the intraneuronal T3 comes through the local deiodination of T4. The present investigation indicates a tendency for synaptosomal reorientation of T3 level for vital neurophysiologic function in altered thyroid conditions.

Animals↗
PubMed1994

Transforming growth factor alpha: a modifying locus for nonsyndromic cleft lip with or without cleft palate?

Most (but not all) studies have found weak but significant association between restriction fragment length polymorphisms at the transforming growth factor alpha (TGFA) locus on chromosome 2p13 and nonsyndromic cleft lip with or without cleft palate (CL +/- P). However, all attempts to demonstrate genetic linkage between TGFA and CL +/- P in families have produced consistently negative lod scores which provide evidence against linkage. We typed a 3-allele single-strand conformation polymorphism at TGFA in 14 extended families with multiple CL +/- P members from West Bengal, India. No significant TGFA differences were observed between the entire sample of 34 affected people and a sample of 38 unaffected people unrelated to each other (p = 0.39). However, affected individuals with CL only showed significant differences from unaffected individuals (p = 0.008). More interestingly, the CL only and CL+P groups of individuals differed strongly from each other in their TGFA frequencies (p = 0.0002). Using an autosomal dominant model with reduced penetrance for the inheritance of a major CL +/- P locus (suggested by our prior segregation analyses), a non-significant maximum lod score of 0.13 at a recombination frequency of 20% was obtained. We suggest that the TGFA locus only modifies expression (severity) of the CL +/- P trait, which is controlled by a major (necessary) locus elsewhere; this could explain the difficulty in obtaining positive linkage results.

Alleles↗
PubMed1994

Ondansetron 4 mg for the prevention of nausea and vomiting after minor laparoscopic gynaecological surgery.

We studied the efficacy and safety of intravenous ondansetron 4 mg for the prevention of postoperative nausea and vomiting after minor gynaecological laparoscopic surgery in Oriental women. This double-blind randomised study compared ondansetron with placebo, given before the induction of anaesthesia. The anaesthetic technique used thiopentone, fentanyl, atracurium, nitrous oxide and isoflurane. Patients were studied for 24 h with nausea assessed using a verbal numeric scale from 0-10 and emetic episodes recorded as they occurred. Results were available for 102 patients in each group. In the first postoperative hour, fewer patients in the ondansetron Group (12%) had emetic episodes compared with the placebo group (33%, P < 0.01). Nausea score over the first hour (sum of three readings at 0, 30 and 60 min) was lower in the ondansetron group (median 1.6) compared with the placebo group (3.1, P < 0.05). Over the 24 h period, fewer patients in the ondansetron group had emetic episodes (25%) or nausea (43%) compared with patients in the placebo group (56%, P < 0.01) and (58%, P < 0.05) respectively. No adverse events were seen. Ondansetron 4 mg was more effective than placebo in preventing postoperative nausea and vomiting throughout the 24 h after minor laparoscopic surgery.

Adult↗
PubMed1993

17 beta-Hydroxysteroid dehydrogenase activity of ovary and hepatopancreas of freshwater prawn, Macrobrachium rosenbergii: relation to ovarian condition and estrogen treatment.

The activity of 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) was determined in the hepatopancreas and the ovary of freshwater prawn Macrobrachium rosenbergii, at different stages of life. A uniform level of 17 beta-HSD activity was observed in the hepatopancreas of immature, maturing, matured, and gravid prawns, whereas the activity of this enzyme was found to be higher in the ovary of the maturing prawn only. Gradual increases in the GSI values and ovarian protein content at the different stages of maturity were observed in this animal. Between the two organs, higher activity of 17 beta-HSD was observed in the hepatopancreas of the prawn in the maturing stage. The estradiol-17 beta (E2) level measured by radioimmunoassay showed its peak in both the hemolymph (126.0 +/- 7.0 pg/ml) and the ovary (300.00 +/- 9.0 pg/mg protein) in the maturing prawn only compared to that in immature, matured, and gravid prawns. The hormone level became undetectable in the hemolymph and remained about 10-fold less (30.6 +/- 5.0 pg/mg protein) in the ovary of the gravid prawn in comparison to the prawns in the maturing stage. A parallelism between the nature of 17 beta-HSD activity and the hormone level was observed in the ovary at different stages of life. A dose-dependent stimulation of 17 beta-HSD activity was observed in the hepatopancreas of the maturing prawn after three consecutive injections of 0.25, 0.5, 1.0, and 2.0 micrograms/g of estradiol-17 beta (E2) on the 4th day of treatment compared to the control values.(ABSTRACT TRUNCATED AT 250 WORDS)

17-Hydroxysteroid Dehydrogenases↗
PubMed1993

Subcellular action of estradiol-17 beta in a freshwater prawn Macrobrachium rosenbergii.

Injections with different doses (0.1, 0.25, 0.5, 1.0, 2.0, and 4.0 micrograms/g) of estradiol-17 beta (E2), administered three days consecutively, showed a statistically significant increase in mitochondrial Na(+)-K(+)-ATPase, cytosolic malate dehydrogenase, and cytosolic glucose-6-phosphate dehydrogenase activities in a dose-dependent manner in the hepatopancreas of the freshwater prawn (Macrobrachium rosenbergii) on the 4th day of treatment compared to the control values. A lower dose of 0.05 microgram/g was without any effect on these enzyme activities. A uniform increase in the Mg(2+)-ATPase activity was observed after injections with 0.5, 1.0, and 2.0 micrograms/g of E2. Ergosterol, a nonsex steroid did not show any change in the malate dehydrogenase and glucose-6-phosphate dehydrogenase activities on which this compound was tested at a 2.0 micrograms/g dose, compared to the control values. Simultaneous injection of tamoxifen (0.5 microgram/g), an antiestrogenic compound, with E2 (2 micrograms/g) caused inhibition of the E2-induced rise in mitochondrial Na(+)-K(+)-ATPase and cytosolic NADP-linked malate dehydrogenase activities. Conversely, tamoxifen (0.5 and 1.0 microgram/g) behaved as an estrogen agonist to the response (increase) of Mg(2+)-ATPase and cytosolic glucose-6-phosphate dehydrogenase activities. Potentiation of the estrogen effect with tamoxifen (1.0 microgram/g) was observed in these enzyme activities when used simultaneously with E2 (2 micrograms/g). Use of cycloheximide (0.5 mg/liter), a protein synthesis blocker, inhibited the inhibited the E2 (2 micrograms/g)-induced increase in all the enzyme activities studied. The data show specific and prominent subcellular action of estrogen with an indication of its role in energy-dependent ion transport and metabolic activation in hepatopancreas of the freshwater prawn.

Animals↗
PubMed1993

Surface ultrastructure of human dermis and wounds.

Scanning electron microscopic observations of the de-epidermalized surfaces of wounds and control skin reveal the architecture of dermal collagen. At wound edges there is a transition from the normal regular rete peg structure through erratically shaped finger-like projections with buds, to the relatively flat surface of granulation tissue. A corresponding change in the ultrastructure of dermal collagen is seen from normal areas where bundles of thick fibres are made up from finer fibrils, through a transitional zone where only fine fibrils are visible, to the granulation tissue where a disorganised amorphous structure is seen. It is suggested that the fibrous tissue surface at the edges of healing wounds is extensively remodelled after it is covered by epidermal cells.

Basement Membrane↗
PubMed1993

Synaptosomal action of thyroid hormone: changes in Na(+)-K(+)-ATPase activity in adult rat cerebral cortex.

In view of the lack of knowledge on the thyroid hormone (T3) action in adult mammalian brain the present investigation was undertaken to assess the role of this hormone on synaptosomal function of adult rat cerebral cortex. Single injection of various doses of T3 showed dose-dependent inhibition of the synaptosomal Na(+)-K(+)-ATPase activity with its maximum effect at 24 hr in comparison to the untreated control values. The magnitude of the inhibitory response of T3 gradually diminished with the advancement of time (48 and 72 hr). Propylthiouracil (PTU) treatment caused stimulation of the synaptosomal Na(+)-K(+)-ATPase activity in comparison to the untreated control animals. T3 treatment to the PTU-treated animals showed inhibition of the Na(+)-K(+)-ATPase activity at a level very similar to that found in only T3-treated animals. The study indicates involvement of T3 in synaptosomal function of adult rat.

Animals↗
PubMed1993

Nonsyndromic cleft lip with or without cleft palate in west Bengal, India: evidence for an autosomal major locus.

Ninety extended families having one or more individuals affected with nonsyndromic cleft lip (CL) with or without cleft palate (CL/P) were ascertained in rural West Bengal, India. These families included 138 affected people, 64% of whom had CL alone and 66% of whom were male. Multiple-affected-member ("multiplex") pedigrees were less common than single-affected-member ("simplex") pedigrees, composing 34% of all extended pedigrees. There was no difference between multiplex and simplex pedigrees in the frequency of affected persons with CL alone, but multiplex pedigrees had a lower frequency of affected males (58%) than did simplex pedigrees (76%; P = .02). Complex segregation analysis using the POINTER computer program rejected both the hypothesis of no familial transmission (P < .0001) and the hypothesis that familiarity could be explained solely by a multifactorial/threshold model (P < .05). The hypothesis of major-locus inheritance alone could not be rejected. Among major-locus models examined, strictly recessive inheritance was rejected (P < .0001), but codominant and dominant models were not. Neither the addition of a multifactorial component nor the addition of a proportion of sporadic cases to the major-locus model improved the fit of the data. In conclusion, the results of complex segregation analysis were consistent with a dominant or codominant major-locus mode of inheritance of CL/P in these families.

Adult↗