Search PubMed⌕ Search

Biomedical subjects

S Bhattacharya

Publications and source records attributed to S Bhattacharya.

At least 325 records · Page 18Linked to original sources
PubMed1994

Nucleotide sequence organisation and analysis of the nuclear ribosomal DNA circle of the protozoan parasite Entamoeba histolytica.

We have sequenced the extrachromsomal ribosomal DNA (rDNA) circle of the human protozoan parasite Entamoeba histolytica HM-1:IMSS and present here the complete sequence organisation of the 24.5-kb molecule. Each circle contains two 5.9-kb rDNA transcription units organised as inverted repeats. The regions downstream (3543 bp) and upstream (9216 bp) of the rDNAs contain various families of short tandem repeats. Some of the upstream repeats share extensive sequence homology with the downstream repeats. In addition to the rDNAs themselves, the rDNA circle appears to code for only one other transcript which is 0.7 kb in size as seen in Northern blots. From DNA sequence analysis, no open reading frame could be assigned to the transcript. Extrachromosomal rDNA circles also exist in other E. histolytica strains. Restriction enzyme maps of rDNA circles were constructed from E. histolytica strains 200:NIH, HK-9 and Rahman; and Entamoeba moshkovskii strain Laredo. Striking differences were observed in the organisation of some of them, e.g. the HK-9, Rahman and Laredo circles contained only one rDNA unit and lacked the 0.7-kb transcript sequence. The short repeat sequences upstream and downstream of rDNAs were present in HK-9 and Rahman but absent in Laredo. Circles with one rDNA unit may be derived from those with two units by homologous recombination at direct repeat sequences located upstream and downstream of the two rDNAs.

Animals↗
PubMed1994

Macular dystrophy associated with mutations at codon 172 in the human retinal degeneration slow gene.

BACKGROUND: Recently, mutations in the retinal degeneration slow (rds) gene which codes for peripherin-rds have been implicated as a cause of autosomal dominant retinitis pigmentosa. Because this gene is expressed in both rods and cones, mutations in the rds gene might be expected to cause degeneration affecting either the scotopic or photopic systems. Mutations at codon 172 of the rds gene have been identified in three families with autosomal dominantly inherited, progressive macular dystrophy. METHODS: Affected individuals underwent ophthalmic examination, scotopic perimetry, dark adaptometry, measurement of color-contrast sensitivity, and electroretinography to characterize the photoreceptor dysfunction. RESULTS: In all but one affected member, symptoms of progressive central visual loss developed in the third or fourth decade of life accompanied by central scotoma and well-demarcated atrophy of the retinal pigment epithelium and choriocapillaris of the macula. In general, cone and rod thresholds were elevated, and color-contrast sensitivity was absent in the central visual field. Peripherally, the scotopic sensitivities were normal, as was the recovery from bleach. Cone electroretinograms were diminished in amplitude, and delayed in all affected adults except one. Rod electroretinograms were normal or near normal in amplitude, and had normal implicit times. Affected asymptomatic children had macular changes, abnormal color-contrast sensitivity, and reduced pattern and cone electroretinograms. CONCLUSION: These results indicate that mutations in the rds gene can be expressed as a macular dystrophy, with evidence of primary cone dysfunction and preservation of peripheral rod function.

Adolescent↗
PubMed1994

Isolation and characterization of a species-specific multicopy DNA sequence from Entamoeba histolytica.

A genomic library of Entamoeba histolytica (pathogenic strain HM-1:IMSS) was screened to detect repetitive DNA clones other than those from the highly abundant ribosomal DNA (rDNA). One such clone (HMc) had a 2.3 kb insert which hybridized with the main genome and not the rDNA circle. Southern hybridization of E. histolytica genomic DNA, digested with EcoR I and probed with HMc, showed multiple bands. The banding pattern was identical in all axenic pathogenic strains tested. Differences, however, existed when the banding pattern of a pathogenic strain was compared with that of a non-pathogenic strain. HMc was present in about 25-30 copies per genome in strain HM-1:IMSS. Nucleotide sequence analysis of HMc revealed a partial open reading frame which hybridized with a 1.35 kb poly A+ transcript in Northern blots. The deduced amino acid sequence did not, however, show significant homology with known proteins. The HMc sequence was found only in E. histolytica as it hybridized with 5 different axenic strains of E. histolytica but did not recognize other closely related species of Entamoeba. It has thus the potential to be used as a species-specific DNA probe.

Amino Acid Sequence↗
PubMed1994

Genetic linkage of cone-rod retinal dystrophy to chromosome 19q and evidence for segregation distortion.

Inherited retinal dystrophies are the most common cause of childhood blindness in the developed world. Cone-rod retinal dystrophies are severe examples of this group of disorders. Analysis of a large cone-rod dystrophy pedigree suggested that inheritance within the family was influenced by meiotic drive (p = 0.008), a rare segregation distortion in human genetics. Two-point linkage analysis showed significant linkage with three markers mapping to chromosome 19q. Multipoint analysis gave a maximum lod score of 10.08 (theta = 0.05) distal to D19S47. Cone-rod dystrophy is therefore assigned to 19q13.1-q13.2 and a new candidate locus for other retinal dystrophies is identified.

Child↗
PubMed1994

The apolipoprotein B messenger RNA editing enzyme.

The editing of apolipoprotein (apo)B messenger RNA (mRNA) involves a novel C to U modification, which creates an in-frame stop-translation codon, thereby generating the carboxyl-terminal of apoB48. The 27 kDa catalytic subunit of the editing enzyme has been cloned and established to be a zinc-containing cytidine deaminase. The catalytic subunit is guided to the editing site by a second targeting subunit or subunits. A candidate for the targeting subunit is a 60 kDa protein that can be UV crosslinked to the sequence UGAU, which is part of a motif downstream of the editing site that is essential for editing.

Amino Acid Sequence↗
PubMed1994

Diameters of juxtacapillary venules determined by oil-drop method in rat lung.

We report a new method for precise quantification of lung microvascular diameter. Isolated blood-perfused rat lungs (500-g Sprague-Dawley rats) at constant inflation pressure [alveolar pressure (PA)] and stopped blood flow were viewed by microscopy and video. Subpleural venules of the second and third postcapillary generations were microinjected with oil colored with Sudan Black. Vascular pressure (Pvas) was varied in steps, and at each step the horizontal diameter (DH) and the length of the oil-filled segment were determined by microcaliper measurements of the replayed video image. At PA = 5 cmH2O, a decrease in Pvas from 25 to 0 cmH2O decreased DH in the second-generation venules from 55 +/- 2 (SE) to 41 +/- 1 microns (n = 13) and in the third-generation venules from 96 +/- 6 to 73 +/- 6 microns (n = 6). The constant-volume oil-filled segment conformed to the cylinder formula in that decreases in DH correlated linearly with 1/ square root of length, thereby indicating that at all Pvas values venular geometry was constant and probably circular in cross section. The decrease in Pvas to -5 cmH2O did not further decrease DH. At Pvas = 10-25 cmH2O, an increase in PA to 15 cmH2O did not significantly increase DH, although the increase in PA did diminish the slope (compliance) of the DH-Pvas relationship in second- but not third-generation venules. We conclude that 1) lung expansion decreases compliance of juxtacapillary venules, 2) venules retain circular cross sections at Pvas between -5 and 25 cmH2O, and 3) venules are patent at subzero Pvas.

Animals↗
PubMed1994

Abdominal wall haematoma complicating laparoscopic cholecystectomy.

Of 61 consecutive patients undergoing laparoscopic cholecystectomy, 4 (6.25%) developed abdominal wall haematomas. This complication of laparoscopic cholecystectomy may occur more commonly than existing literature suggests, and manifests in the post-operative period (days 2 to 6) by visible bruising, excessive pain or an asymptomatic drop in haematocrit. It is readily confirmed by ultrasonography. While no specific treatment is necessary apart from replacement of significant blood loss, the patient requires reassurance that this apparently alarming complication will rapidly resolve.

Abdominal Muscles↗
PubMed1994

Case report: localization of lipiodol-radioiodine in hepatic metastases from renal cell carcinoma.

Lipiodol, an iodinated derivative of poppyseed oil, is selectively retained in hepatocellular carcinoma and has been used as a vehicle to deliver localized doses of chemotherapeutic and radioactive agents to such tumours, thereby reducing the problems of external beam irradiation and the systemic toxicity of chemotherapy. We describe the first reported case where Lipiodol-targeted radiotherapy has been administered to a patient with secondary renal cell carcinoma in the liver. Localization was good and there were no complications. This case suggests that in future such patients may benefit from this therapy for unresectable lesions.

Carcinoma, Renal Cell↗
PubMed1994

Functional relevance of luteinizing hormone receptor in mouse uterus.

The presence of high-affinity luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptors has been reported in porcine, rabbit, rat and human uteri. We have demonstrated binding of [125I]LH to mouse uterus, which was saturable. Scatchard plot analysis indicated Kd to be 1.37 x 10(-10) mol/l and the maximum binding capacity to be 5.24 nmol/kg protein. Attempts have been made to observe the functional relevance of gonadotropin receptor in the mouse uterus. The size and weight of the uterus remarkably decreased as a result of ovariectomy; administration of LH to ovariectomized (OVX) mice significantly increased the uterine weight in comparison to the OVX control (p < 0.01), indicating a direct effect of LH on the uterus. There was a two-fold decrease of uterine ascorbic acid content in LH-treated OVX mice as compared to the intact control. The gain in uterine weight of OVX mice by LH was due to the increase in uterine protein synthesis. The stimulatory effect of LH on OVX mice uterus appears to be mediated via steroid hormones because it significantly augmented uterine mitochondrial steroidogenesis. Since 17 beta-estradiol (E2) is known to stimulate uterine protein synthesis, the circulatory level of E2 was determined in intact, OVX and OVX + LH-treated mice. A fall in the circulatory level of E2 occurred in OVX mice as compared to the control, while treatment of LH for 7 days (three injections) significantly elevated E2 levels in OVX mice (p < 0.001). This higher level of E2 in OVX mice remains unaltered on adrenalectomy, indicating that adrenals are not the source for increased E2 levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Binding of thyroid hormone to the goat testicular Leydig cell induces the generation of a proteinaceous factor which stimulates androgen release.

Leydig cells isolated from goat testis were sonicated and pure nuclear preparations obtained for 125I-3,5,3'-triiodothyronine (T3)-binding assay. Under optimum assay conditions of pH 7.2 at 37 degrees C and 90 min of incubation, binding of 125I-T3 to Leydig cell nuclei reached saturation at 1.2 nmol/l concentration. A Scatchard analysis of T3 binding exhibited a Kd of 0.535 x 10(-9) mol/l and a maximum binding capacity of 1.25 pmol/mg DNA. Competitive inhibition studies showed T3 binding to be analogue specific. The physiological relevance of T3 binding to goat Leydig cell was examined by adding increasing concentrations of T3 to the Leydig cell incubation (1 x 10(6) cells/incubation). T3 (10, 25 and 50 ng/ml or 4, 10 and 20 ng/incubation) resulted a dose dependent increase in androgen release and in all cases stimulation of androgen release was statistically significant (P < 0.01) compared with control. Stimulation of Leydig cell androgen release by T3 was significantly inhibited by actinomycin-D (P < 0.01) and cycloheximide (P < 0.01). T3 had additive stimulatory effects on LH-augmented androgen release from Leydig cells. T3 (50 ng/ml or 20 ng/incubation) effected a more than twofold increase in Leydig cell protein synthesis compared with control and both actinomycin-D and cycloheximide (50 micrograms/ml) inhibited it completely. The data indicated that the stimulatory effect of T3 on androgen release is mediated via T3-induced protein(s).(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens↗
PubMed1994

Correlation of metal distribution, reduced glutathione and metallothionein levels in liver and kidney of rat.

Effect of group IIB metals on the endogenous status of metallothionein (MT) and reduced glutathione (GSH) was studied in two vital detoxifying organs namely, liver and kidney of rat. The metals were administered at non lethal levels (1/10 LD50) which were found to cause no death. Zinc showed accumulation in both liver and kidney, cadmium preferentially in the liver while mercury in the kidney. Hepatic MT content was increased by 18-fold, 15-fold and 2-fold by cadmium, zinc and mercury respectively while renal MT was increased maximally by zinc. Among the metals, mercury caused highest depletion of hepatic GSH level (51%). The renal GSH showed differential response to the metal treatment, the level increasing slightly by cadmium and depleting significantly by zinc and mercury. A positive correlation was found between group IIB metal accumulation and the manifestation of toxic response.

Animals↗
PubMed1994

Induction of metallothionein in rat liver by cadmium chloride: probable mechanism of action.

The mechanism of action of cadmium in the inductive pathway of metallothionein (MT) synthesis was studied in the rat. Cadmium significantly elevated the MT level by 872% which was antagonised by coadministration of either verapamil (343.5%) or ionophore (570%). The Ca-dependent biomolecules such as cyclic AMP or calmodulin remained depressed in all treatment regimens except calmodulin in the ionophore treated rat. Total Ca2+ showed no increase in its profile except in the ionophore treatments either alone or with CdCl2. The Na+ profile is, however, significantly elevated in all cases except the ionophore treated rat. The present study clearly indicates that (a) Ca2+ has no first messenger role in the schematic events leading to MT synthesis and (b) Na+ may be regarded as a possible candidate in the molecular events of Cd-induced MT synthesis.

Animals↗
PubMed1994

Clinical and endoscopic evaluation of gastroduodenal haemorrhage.

Endoscopic evaluation of 100 consecutive cases of haematemesis and melaena attending the emergency ward of NRS Medical College, Calcutta 700014 showed that in 2/3rd of all the patients acid peptic disease was the cause of bleeding, out of which 60% was due to duodenal ulcer and 40% was due to gastric ulcer. Five per cent of all the cases were having portal hypertension where the cause of bleeding was oesophageal varices. Gastric malignancy was responsible for bleeding in 3% cases. In about 6% cases bleeding was due to acute gastric erosion caused by NSAID, steroid and other corrosive agents. In 20% patients no apparent cause for upper gastro-intestinal haemorrhage could be detected endoscopically.

Adolescent↗