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Biomedical subjects

S Bhattacharya

Publications and source records attributed to S Bhattacharya.

At least 343 records · Page 19Linked to original sources
PubMed1994

Evaluation of phthalmustine, a new anticancer compound. I. Effect on Dalton's ascitic lymphoma in mice.

The anticancer property of phthalmustine, a hitherto unknown compound containing N-mustard attached to the phthalimide ethyl chain was evaluated using a murine tumor model. The results indicate that the compound was effective in significantly restraining tumor growth. This was accompanied by marked improvement in host survival. No toxic reactions were apparent as reflected in skin and hair texture, body weight and behavioral pattern (food and water intake and activity). Blood picture showed a shift towards the normal following treatment. DNA synthesis in tumor cells was found to be affected as revealed by radioactive thymidine incorporation.

Animals↗
PubMed1993

The p27 catalytic subunit of the apolipoprotein B mRNA editing enzyme is a cytidine deaminase.

The messenger RNA for apolipoprotein B undergoes a discrete and specific C to U editing of nucleotide 6666. This generates a stop translation codon and defines the carboxyl terminus of apolipoprotein B48. A 27-kDa rat intestinal protein that does not itself edit apolipoprotein B mRNA, but confers editing activity on chick intestinal extracts that do not have intrinsic editing activity, has recently been identified and its cDNA cloned (Teng, B., Burant, C. F., and Davidson, N. O. (1993) Science 260, 1816-1819). Here we show that p27 is homologous in the zinc coordinating region of the active site to cytidine deaminases from Escherichia coli, Bacillus subtilis, yeast, and man and to deoxycytidylate deaminases from T2 and T4 bacteriophages and man. p27 expressed in Xenopus laevis oocyte extracts has cytidine deaminase activity and specifically confers editing activity on chick intestinal extracts. The homologous E. coli cytidine deaminase does not confer editing activity. The zinc-specific chelating agent o-phenanthroline abolishes p27 activity and site-specific apolipoprotein B mRNA editing in rat enterocyte editing extracts. We conclude that p27 is the catalytic subunit of the apolipoprotein B mRNA editing enzyme and is a zinc-containing cytidine deaminase.

APOBEC-1 Deaminase↗
PubMed1993

Cloning of an adenosine A1 receptor-encoding gene from rabbit.

A partial cDNA encoding the A1 adenosine receptor (A1AR), which lacks nucleotides coding for the first 74 amino acids (aa), was isolated from a rabbit kidney cDNA library. The missing 5' end sequence was obtained from an overlapping rabbit genomic clone which was found to contain the flanking 5' untranslated region (5'UTR), the first exon and part of the first intron. Together, the cDNA and genomic clones provide the entire open reading frame (ORF) encoding rabbit A1AR. The deduced aa sequence is highly homologous to the canine, rat and bovine A1ARs. These data also indicate that the A1AR gene belongs to the family of intron-containing G-protein-linked receptor genes.

Adenosine↗
PubMed1993

Evaluation of 'cypenhymustine', a new anticancer compound, in murine tumour models.

'Cypenhymustine', 3-[2-[bis(2'-chloroethyl)-amino] ethyl]-5,5- tetramethylenehydantoin, has been synthesised as a potential analog of spiromustine (NSC 172112). The LD50 value was determined in Swiss male mice and found to be 65.0 mg/kg by single i.p. injection. In in vivo screening experiments, three parameters, namely, ascites cell count, ascites fluid measurement and increase in life span (ILS) of drug-treated over control Swiss mice were studied in three murine ascites tumours namely Ehrlich ascites carcinoma (EAC), sarcoma-180 (S-180) and Dalton's lymphoma (DL). Cypenhymustine exhibited a very high percentage of inhibition of both the ascites cell and fluid in these models and also displayed excellent reproducible ILS activity (ILS values of 151 in EAC, 157 in S-180 and 181 in DL at the optimum dose of 3 mg/kg for days 1-7 treatment following tumour transplant on day 0) having a 'curative' effect (1-2 animals: 6 having > 60 days survival rate). The chemical alkylating activity has been compared with spiromustine and another antitumour agent namely nor-HN2.

Animals↗
PubMed1993

Palmitoylation of bovine opsin and its cysteine mutants in COS cells.

Previously, bovine rhodopsin has been shown to be palmitoylated at cysteine residues 322 and 323. Here we report on palmitoylation of bovine opsin in COS-1 cells following expression of the synthetic wild-type opsin gene and several of its cysteine mutants in the presence of [3H]palmitic acid. Two moles of palmitic acid are introduced per wild-type opsin molecule in thioester linkages. Palmitoylation is abolished when both Cys-322 and Cys-323 are replaced by serine residues. Replacement of Cys-322 by serine prevents palmitoylation at Cys-323, whereas replacement of the latter with serine allows palmitoylation at Cys-322. Opsin mutants that evidently do not contain a Cys-110/Cys-187 disulfide bond and presumably remain in the endoplasmic reticulum are not palmitoylated. Replacement of Cys-140 or Cys-185 reduces the extent of palmitoylation of the opsin. Lack of palmitoylation at Cys-322 and/or Cys-323 does not affect 11-cis-retinal binding, absorption maximum or extinction coefficient of the chromophore, the bleaching behavior of the chromophore, or the light-dependent binding and activation of transducin. Mutants containing serine substitutions at Cys-140 or Cys-323 showed reduced light-dependent phosphorylation by rhodopsin kinase.

Amino Acid Sequence↗
PubMed1993

Rhodopsin mutations in autosomal dominant retinitis pigmentosa.

Retinitis pigmentosa is an inherited progressive disease which is a major cause of blindness in western communities. It can be inherited as an autosomal dominant, autosomal recessive, or X-linked recessive disorder. In the autosomal dominant form (adRP), which comprises about 25% of total cases, approximately 30% of families have mutations in the gene encoding the rod photoreceptor-specific protein rhodopsin. This is the transmembrane protein which, when photoexcited, initiates the visual transduction cascade. So far, 41 single-base-pair (bp) substitutions, one two-bp substitution, and four deletions ranging from 3 to 42 bp have been identified in this gene. These mutations do not appear to be significantly clustered in a specific part of the protein, but occur in all three major domains, namely the intradiscal, transmembrane, and cytoplasmic regions. Different mutations appear to cause differences in the severity of the disease, though there is considerable variability in severity even within the same family, at least in certain of these mutations. Identification of all the mutations involved in rhodopsin-RP should allow accurate and early detection of affected individuals, informed genetic counselling, as well as furthering our knowledge of the disease process involved.

Amino Acid Sequence↗
PubMed1993

Purification and properties of an Indian major carp (Cirrhinus mrigala, Ham.) pituitary thyrotropin.

Thyroid stimulating hormone (TSH) was isolated and purified from the pituitaries of Indian major carp, Cirrhinus mrigala, with the help of a sensitive in vitro bioassay system, based on incubating isolated thyroid follicles from murrel, Channa gachua. In this assay, addition of test material containing TSH increased thyroxine (T4) release into the medium which was then measured by radioimmunoassay (RIA). TSH activity was eluted as one major peak on Sephadex G-100 gel filtration (peak I), which also contained gonadotropin (GtH) and extraneous proteins as contaminants. GtH was monitored by RIA. Chromatography of peak I of gel filtration on concanavalin A-Sepharose was useful in harvesting glycoprotein hormones; adsorbed (Con A-II) material showed strong TSH activity and low GtH content. To separate TSH from GtH completely, immunoaffinity chromatography was used; more than a 200-fold purification was achieved. Polyacrylamide gel electrophoresis of carp TSH (cTSH) showed a single band, indicating it to be a homogenous protein. The molecular weight (MW) of cTSH was estimated by Sephadex G-100 gel filtration to be 42,000 Da. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cTSH revealed two dissimilar subunits, alpha and beta, and MW of alpha was 21,000 Da while that of beta was 24,000 Da. When tested in similar doses, cTSH released more T4 from murrel thyroid follicle than bovine TSH (bTSH). cTSH stimulated the T4 release from rat and goat thyroid but its activity was less than that of bTSH. Radiolabeled cTSH (125I-cTSH) bound specifically to a murrel thyroid follicular plasma membrane preparation, and Scatchard analysis showed the Kd to be 0.17 x 10(-10) M and the maximum binding (Bmax) to be 15.2 fmol/mg protein. 125I-cTSH also binds to the goat thyroid plasma membrane preparation with a Kd = 0.23 x 10(-10) M and a Bmax = 9.8 fmol/mg protein. Findings indicate that carp pituitary thyrotropin is approximately similar in size to that of vertebrates, its biological activity is not restricted only to fish but is also observed in rat and goat, and it has a receptor in teleost and goat thyroid.

Animals↗
PubMed1993

99mTc-antimyosin antibody imaging for the detection of acute myocardial infarction in human beings.

111In-antimyosin imaging is a highly sensitive and specific technique for the detection of myocardial necrosis. Two new methods of labeling antimyosin with 99mTc have been developed, and were compared with the standard 111In-antimyosin imaging technique in 29 patients with acute myocardial infarction. Fourteen patients (group I) received directly labeled 99mTc-antimyosin, and 15 (group II) were given RP-1 conjugated 99mTc-antimyosin. 99mTc-antimyosin imaging was performed at 6, 12, and 24 hours, and 111In-antimyosin imaging was done at 24 and 48 hours following injection. The images were interpreted by three blinded observers. In group I, 99mTc-antimyosin uptake could be detected in 3, 6, and 12 cases at 6, 12, and 24 hours, respectively, compared with only 8 cases at 24 hours with 111In-antimyosin. At 48 hours all patients showed 111In-antimyosin uptake. In group II, 99mTc-antimyosin uptake could be detected in 2, 3, and 6 cases at 6, 12, and 24 hours, respectively, compared with 8 and 12 cases at 24 and 48 hours, respectively, with 111In-antimyosin. Gated blood pool studies could be obtained in all patients following 99mTc-antimyosin injection and could be used to identify regional wall motion abnormalities. The plasma half-lives of 99mTc-antimyosin in group I and group II were 2.67 +/- 0.3 hours and 4.23 +/- 0.3 hours, respectively, and the plasma half-life of 111In-antimyosin was 6.3 +/- 0.4 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Studies of operational variables in batch mode for genetically engineered Escherichia coli cells containing penicillin acylase.

A recombinant Escherichia coli was constructed by cloning the penicillin acylase gene from E. coli ATCC 11105. The cloning was carried out using a recombinant plasmid pUSAD2 harboring the pac gene. The recombinant E. coli DH 5 cells were used as a biocatalyst and were studied in a batch reactor for determination of optimum value for some of the process parameters, such as effect of pH, temperature, substrate concentration, kLa and effect of carbon and nitrogen source on penicillin acylase production. These values were then compared with the values obtained with the standard parent strain. Whereas the cloned pac gene was found to produce higher levels of penicillin acylase constitutively, the process parameters remained about the same for both the parent and the recombinant.

Cloning, Molecular↗
PubMed1993

Distribution kinetics of inorganic mercury in the subcellular fractions of fish liver.

The present study tries to find out the kinetics of distribution of mercury in the different subcellular fractions of the liver in a freshwater perch Anabas testudineus over a period of 48 h after a single i.m. injection of [203Hg]mercuric nitrate at a dose of 4 mg/kg body weight. The fish were killed at 15 min, 2 h, 6 h and 48 h post injection. In addition the interaction of this metal with different biomolecules, viz., protein, DNA and RNA, was also investigated. Cytosol was found to be the major site of mercury accumulation. Moderate amounts of accumulation occurred in the nuclear, mitochondrial and microsomal fractions, although varying with time, while the lysosomal fraction did not reveal any spectacular retention of mercury. A significant increase in the protein content of nuclear, mitochondrial, lysosomal and cytosolic fractions was also noticed at different time periods of mercury injection. In the nuclear, microsomal and cytosolic proteins, mercury binding increased more significantly over time than the mitochondrial and lysosomal proteins. A biphasic binding pattern of mercury was seen in nuclear and mitochondrial DNA and mitochondrial and cytosolic RNA.

Animals↗
PubMed1993

Mutations in the human retinal degeneration slow (RDS) gene can cause either retinitis pigmentosa or macular dystrophy.

Mutations in the RDS gene, which encodes the photoreceptor glycoprotein peripherin, have been sought in families with autosomal dominant retinal dystrophies. A cysteine deletion at codon 118/119 is associated with retinitis pigmentosa in one. Three families with similar macular dystrophy have mutations at codon 172, arginine being substituted by tryptophan in two and by glutamine in one. A stop sequence at codon 258 exists in a family with adult vitelliform macular dystrophy. These findings demonstrate that both retinitis pigmentosa and macular dystrophies are caused by mutations in RDS and that the functional significance of certain amino-acids in peripherin-RDS may be different in cones and rods.

Adult↗