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Biomedical subjects

S Das

Publications and source records attributed to S Das.

At least 505 records · Page 28Linked to original sources
PubMed1991

Isolation and cloning of Bacillus thuringiensis var Kurstaki HD73 toxin gene and construction of a chimaeric gene for expression in plants.

Necessity for the production of transgenic crop plants of India, capable of expression of insecticidal Bt protein in plant to combat lepidopteran pest damage has been strongly felt. Bacillus thuringiensis Kurstaki HD73 crystal protein coded by CryIA(c)73 gene has been found to be sufficiently effective against the major pests of jute and chickpea. An attempt to isolate the gene and make its use in a chimaeric gene construct for expression in plant was carried out. The plasmid CryIA(c)73 gene was cloned and tailored at the 3' end. The expression of the truncated gene was monitored in the minicell systems of E. coli. The entomocidal property was found to be fully retained by the gene product. Deletion of the nucleotides at the 5' end was carried out and chimaeric gene construct of cryIA(c)73 was made in such a way that it was fused in frame with GUS gene under the control of the caMV 35S promoter with Nos polyadenylated terminus. Such a chimaeric gene construct was used as the passenger of a Ti plasmid derived plant vector with kanamycin gene (NPTII) as the additional plant marker. Transformation through infection of tobacco and mustard plant cells in culture was carried out. Plants regenerated from the transformed cells showed the presence of GUS gene indicating the expression of the cloned fused gene. Also, Northern analysis established the presence of cryIA(c)73 gene transcripts in the transgenic plants.

Bacillus thuringiensis↗
PubMed1991

Interaction of T-DNA border sequences and Ti-plasmid vir functions of Agrobacterium results in differential single-stranded linear T-DNA molecule production and plant transformation.

The mechanism of Agrobacterium mediated genetic transformation of plants is dependent upon certain genetic function of the chromosome of the bacterium as well as on Ti-plasmid borne vir loci and the border sequences of T-DNA. The organisationally variable forms of the naturally occurring border sequences amongst Ti-plasmid types are differentially responsive to gene products of vir loci concerned with T-strand production. Additionally, the production of stable transformants is dependent upon vir gene products effective after T strands are produced. The interaction of border sequences from different strains of Agrobacterium with vir proteins encoded by various helper plasmids revealed that functional differences do exist amongst vir gene products contained in the type of helper plasmids used.

Base Sequence↗
PubMed1991

Efficacy of carbamazepine in premenstrual syndromes. A report on four cases.

Five patients presented with severe mood disturbance and behaviour change during the premenstruum. Suspiciousness was an important feature in four of them. They were treated with carbamazepine 200-400 mg orally at bedtime for 7 days before the onset of menses. The follow-up period varied from 1 1/2 years to 2 menstrual cycles. Four patients showed remarkable improvement; one patient dropped out because of allergic rash.

Adult↗
PubMed1990

Chromate reduction in Streptomyces.

Streptomyces species 3M grew in peptone yeast extract medium with 1000 micrograms/ml K2Cr2O7. Incubation of the chromate with different cell fractions in the presence of NADH and NADPH resulted in a decrease of Cr6+ in the reaction mixture. The level of Cr6+ was reduced by 82.7% by a particulate cell fraction obtained by centrifugation at 105,000 x g for 1 h, in the presence of NADH. The reducing enzyme was associated with this cell fraction. The enzyme was constitutive and reduced Cr6+ to Cr3+.

Chromates↗
PubMed1990

Exophytic gliomas of the spinal cord.

Intradural extramedullary glial tumours of the spinal cord are rare. We report for such tumours arising from the dorsal cord. Myelography and operative findings were almost similar to that of an intradural neurofibroma. Surgical removal had resulted in rewarding neurological recovery. One of them had a recurrence after six years and was re-explored. Anterolateral attachment near the root entry zone suggests its origin probably from the spinal cord with an exophytic growth.

Adult↗
PubMed1990

Traumatic dislocation of testes.

Traumatic dislocation of the testicle is characterized by an ectopically displaced testis as the result of closed injury. We report on 1 patient with subcutaneous inguinal dislocation of the testis that was successfully treated by immediate closed reduction. Forty-nine other cases (36 unilateral and 13 bilateral) have been previously cited. Diagnostic guidelines, our therapeutic approach, and the relevant literature are presented.

Adult↗
PubMed1990

The photosensitizers benzophenoxazine and thiazines: comprehensive investigation of photophysical and photochemical properties.

Eight differently substituted title dye compounds have been investigated regarding intersystem crossing, triplet state, fluorescence and singlet excited state pKa properties. In general, non-halogenated oxazines and thiazines as well as a mono bromooxazine show very low triplet quantum yields, phi tau (less than 0.03) and relatively long triplet lifetimes (approximately 40 microseconds) in acidic methanol. The phi tau data correlate well with known singlet oxygen yields. In basic methanol no triplet transient is observed but a significant yield of a ground state transient protonated (base dye) form is produced with a short lifetime, approximately 400 ns. Fluorescence can be seen simultaneously from both the excited base and the protonated base dye forms in basic methanol. For iodinated oxazine or thiazines, the triplet yield increases and can be as high as 0.5 (diiodo case) in acidic methanol. The triplet lifetimes are further shortened to approximately 10 microseconds compared to the non-iodinated derivatives above. The triplet yields of the iodo compounds are higher or equal to known singlet oxygen yields. In basic methanol triplet yields up to 0.2 can be seen, the triplet lifetime are shortened still further to 1 microsecond but no observable protonated form is produced (in distinction to the non-iodinated cases). Consideration is given to the correlation of triplet and singlet oxygen yields, ground and excited pKa properties, spin-orbit coupling and internal conversion properties, solvent effects, and phototherapeutic activity of these dyes.

Coloring Agents↗
PubMed1990

Total body irradiation as an alternative to systemic chemotherapy in small-cell anaplastic lung cancer.

The effectiveness of total body irradiation (TBI) plus local radiotherapy in the treatment of small-cell lung cancer was studied in 13 patients, using 4,000 cGy in 15 fractions over three weeks to the local site and 150 cGy in ten fractions over two weeks to the whole body. The mean survival for 12 patients was 31 weeks, with a median survival of 32 weeks. One patient received six courses of combination chemotherapy for recurrent disease four months after TBI without marrow depression and survived 72 weeks, the longest survivor in this series. Brain metastases occurred in only one patient, the most common site of metastases being the liver. All patients tolerated TBI well without nausea, vomiting or hair loss. When bone marrow suppression occurred it was asymptomatic, requiring no treatment and resolving within eight weeks.

Aged↗
PubMed1990

Occurrence of salmonellae in slaughtered pigs, goat meat, meat handlers and slaughtered-house workers.

Of 413 samples comprising 200 goat meat, 100 pig's faeces, 50 faeces of slaughtered-house workers, 13 faeces and 50 nailwashings of goat meat handlers collected from different shops of Calcutta Corporation, 25 (6.05 per cent) yielded 13 serotypes of salmonellae. The commonest serotypes was S. newport (24 per cent), followed by S. enteritidis (12 per cent), S. anatum (12 per cent) and S. typhimurium. Isolation rate of salmonellae was 12 (6 per cent) from goat meat, 10 (10 per cent) in pig's faeces and 3 (6 per cent) in nailwashings. S. newport (50 per cent) in goat meat and S. anatum (30 per cent) in faecal contents of pigs were the predominant serotypes. None of the faecal samples of goat meat handlers and slaughtered-house workers yielded salmonellae.

Abattoirs↗
PubMed1989

The phorbol ester-induced extracellular Ca2+-independent release of LH is dependent on estradiol and de novo protein synthesis.

Phorbol 12-myristate 13-acetate (PMA) was used to determine whether the PMA-induced extracellular Ca2+-independent release of LH was dependent on sex, estradiol and de novo protein synthesis. Infusions of gonadotropin-releasing hormone (GnRH) or PMA in a perifusion system stimulated a partial secretion of LH from diestrous II and ovariectomized + estradiol-treated female pituitaries (responses inhibited by cycloheximide). In contrast, PMA was ineffective in stimulating PRL secretion from these pituitaries, as well as LH secretion from male or ovariectomized female pituitaries. These results indicate that the PMA-stimulated extracellular Ca2+-independent secretion of LH is a specific process which is dependent on sex, estradiol and de novo protein synthesis, and mimics the characteristics of the GnRH-stimulated responses.

Animals↗
PubMed1989

Neuronal degeneration and neurofilament accumulation in the trigeminal ganglia in Creutzfeldt-Jakob disease.

We report the pathological and immunohistochemical changes in the first-order neurons in the trigeminal ganglia in Creutzfeldt-Jakob disease (CJD). Degenerative changes consisted of cytoplasmic vacuolation and fenestration, abundant satellite cells, neurofilament accumulation in neurons, and axonal dystrophy with spheroid formation and torpedolike structures arising from the neuronal cytoplasm. Dystrophic axons, axonal spheroids, and some ganglion cells were labeled with monoclonal antibodies to a phosphorylated epitope of neurofilaments (200 kDa). Polyclonal antibodies to purified scrapie-associated fibril/prion protein (molecular weight 27-30 kDa) extracted from scrapie-infected hamster brains, as well as polyclonal and monoclonal antibodies to a synthetic 15-amino acid polypeptide of the 27- to 30-kDa protein, demonstrated variable immunoreactivity with degenerating neurons in the CJD cases, but not in the controls. Furthermore, some of the satellite cells and dystrophic axons were stained by the antibodies to the synthetic peptide. These data indicate that the first-order neurons of the trigeminal ganglia may form a route by which the CJD agent may travel from the brain to the periphery or vice versa. As in other chronic neurodegenerative diseases, disturbances of neuroaxonal transport seem to occur in CJD.

Adult↗
PubMed1989

Recurrences in meningioma after surgery.

123 cases of meningioma operated upon between 1975 and 1984 were reviewed. There were 13 cases of symptomatic tumour recurrence and 15 cases of tumour progression. Both, recurrence and progression of the tumour were seen twice as often in males. They were not related to any particular age group or site of origin. Recurrence was more common in the angioblastic type of meningioma. In the majority, progression of the tumour was seen within two years of the initial operation, while recurrence of the tumour was distributed evenly over time.

Adolescent↗
PubMed1989

Extracellular Ca2+ controls outward rectification by apical cation channels in toad urinary bladder: patch-clamp and whole-bladder studies.

Outward rectifying, cation channels were observed in the epithelial cells of the urinary bladder of the toad. Bufo marinus. As studied in isolated cells using the patch-clamp technique, the channel has an average conductance of 24 and 157 pS for pipette potentials between 0 and +60 mV and -60 to -100 mV, respectively, when the major cation in both bath and pipette solutions is K+. The conductance of the channel decreases with increasing dehydration energy of the permeant monovalent cation in the order Rb+ = K+ greater than Na+ greater than Li+. Reversal potentials near zero under biionic conditions imply that the permeabilities for all four of these cations are similar. The channel is sensitive to quinidine sulfate but not to amiloride. It shares several pharmacological and biophysical properties with an outwardly-rectifying, vasopressin-sensitive apical K+ conductive pathway described previously for the toad urinary bladder. We demonstrate, in both single-channel and whole-bladder studies, that the outward rectification is a consequence of interaction of the channel with extracellular divalent cations, particularly Ca2+, which blocks inward but not outward current. Various divalent cations impart different degrees of outward rectification to the conductive pathway. Concentrations of Mg2+ and Ca2+ required for half-maximal effect are 3 X 10(-4) and 10(-4) M, respectively. For Co2+ the values are 10(-6) M at +50 mV and a 10(-4) M at +200 mV. The mechanism of blockade by divalent cations is not established, but does not seem to involve a voltage-dependent interaction in which the blocker penetrates the transmembrane electric field. In the absence of divalent cations in the mucosal solution, the magnitudes of inward current carried by Rb+, K+, Na+ and Li+ through the apical K+ pathway at any transepithelial voltage, are in the same order as in the single-channel studies. We propose that the cation channel observed by us in isolated epithelial cells is the single-channel correlate of the vasopressin-sensitive apical K+ conductive pathway in the toad urinary bladder and is also related to the oxytocin- and divalent cation-sensitive apical conductivity observed in frog skin and urinary bladder.

Animals↗