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Biomedical subjects

A K Chatterjee

Publications and source records attributed to A K Chatterjee.

At least 55 records · Page 3Linked to original sources
PubMed1991

Interactions of diabetogenic compounds: cyproheptadine and alloxan.

Pretreatment with an oral dose (45 mg/kg) of cyproheptadine (CPH), a drug that inhibits secretion and synthesis of insulin. 3 hr before alloxan (100 mg/kg, iv) protects mice from the permanent diabetes produced by alloxan. Pretreated animals at the time of alloxan administration were hyperglycemic. Therefore, the possibility that CPH-induced hyperglycemia protected mice from alloxan was investigated. This was accomplished by giving mannoheptulose (a glucose antagonist) or insulin (to lower blood glucose) after CPH and before alloxan. These interventions eliminated CPH-induced protection from alloxan, indicating a role for CPH-induced hyperglycemia in the protective effect. To confirm that CPH does not protect mice from alloxan-induced diabetes by a direct action, in vitro experiments using isolated pancreatic islets were conducted. Mouse islets were pretreated with CPH, its metabolite desmethylcyproheptadine (DMCPH), or an equal mixture of the two and/or various concentrations of glucose prior to an acute exposure to a toxic concentration of alloxan. Glucose-stimulated insulin release was used as a measure of pancreatic beta-cell function after alloxan exposure. CPH or DMCPH (alone or in combination) pretreatment did not provide protection against alloxan-induced inhibition of insulin release nor did pretreatments potentiate the protective action of glucose against in vitro alloxan toxicity. The results indicate that the protective action of CPH when given to mice before alloxan is due to drug-induced hyperglycemia and not to a direct effect of CPH or its metabolite.

Alloxan↗
PubMed1991

Extracellular secretion of pectate lyase by the Erwinia chrysanthemi out pathway is dependent upon Sec-mediated export across the inner membrane.

The plant pathogenic enterobacterium Erwinia chrysanthemi EC16 secretes several extracellular, plant cell wall-degrading enzymes, including pectate lyase isozyme PelE. Secretion kinetics of 35S-labeled PelE indicated that the precursor of PelE was rapidly processed by the removal of the amino-terminal signal peptide and that the resulting mature PelE remained cell bound for less than 60 s before being secreted to the bacterial medium. PelE-PhoA (alkaline phosphatase) hybrid proteins generated in vivo by TnphoA insertions were mostly localized in the periplasm of E. chrysanthemi, and one hybrid protein was observed to be associated with the outer membrane of E. chrysanthemi in an out gene-dependent manner. A gene fusion resulting in the substitution of the beta-lactamase signal peptide for the first six amino acids of the PelE signal peptide did not prevent processing or secretion of PelE in E. chrysanthemi. When pelE was overexpressed, mature PelE protein accumulated in the periplasm rather than the cytoplasm in cells of E. chrysanthemi and Escherichia coli MC4100 (pCPP2006), which harbors a functional cluster of E. chrysanthemi out genes. Removal of the signal peptide from pre-PelE was SecA dependent in E. coli MM52 even in the presence of the out gene cluster. These data indicate that the extracellular secretion of pectic enzymes by E. chrysanthemi is an extension of the Sec-dependent pathway for general export of proteins across the bacterial inner membrane.

Adenosine Triphosphatases↗
PubMed1991

Nucleotide sequence and molecular characterization of pnlA, the structural gene for damage-inducible pectin lyase of Erwinia carotovora subsp. carotovora 71.

In a previous study, pnlA (the DNA damage-inducible structural gene for pectin lyase) of Erwinia carotovora subsp. carotovora 71 was localized to a 1.4-kb DNA segment within a 3.4-kb EcoRI fragment (J. L. McEvoy, H. Murata, and A. K. Chatterjee, J. Bacteriol. 172:3284-3289, 1990). We present here DNA sequence data for a 2.2-kb region revealing an open reading frame of 870 bases, corresponding to a protein (Pnl) of an approximate molecular mass of 32,100 Da and an isoelectric point of 9.92. Although initiation of translation is presumed to occur at the ATG codon, direct protein sequencing revealed alanine as the N-terminal amino acid, probably as a consequence of posttranslational removal of the initiating amino acid. The sequence of the first 20 amino acid residues of Pnl, purified from E. carotovora subsp. carotovora 71, agreed completely with the predicted amino acid sequence of the N-terminal segment. This finding also indicated that Pnl is not subject to processing by a signal peptidase. The transcriptional start site of pnlA was determined to reside 80 bp upstream of the translational start site. Deletion analysis revealed that 218 bp of DNA upstream of the transcriptional start site is sufficient for induction of pnlA by mitomycin C. Within 600 bp upstream of the translational start site, no sequences resembling a LexA binding site (SOS box) or a cyclic AMP receptor protein binding site were found. However, palindromic sequences were detected at -187 and -86 bp relative to the translational start site, and these could be potential sites for the binding of a regulatory protein(s). Comparison of the deduced amino acid sequence for PnlA with that of a Pnl from Aspergillus niger and with those of various pectate lyases of Erwinia species revealed a low degree of homology dispersed throughout the length of the proteins.

Amino Acid Sequence↗
PubMed1991

Rapid alteration of pancreatic proinsulin and preproinsulin messenger ribonucleic acid in rats treated with cyproheptadine.

Cyproheptadine (CPH) appears to be unique among islet beta-cell toxicants by virtue of its ability to rapidly and reversibly inhibit insulin biosynthesis in rats. These studies examined the mechanism of CPH-induced insulin depletion by determining the time course for CPH-induced changes in pancreatic preproinsulin mRNA, proinsulin, and insulin levels. A single oral dose of CPH decreased proinsulin levels to 35% of the control value by 3 h. Proinsulin stayed depressed for up to 24 h. Preproinsulin mRNA declined more slowly, reaching 35% of the control value at 6 h, and increased more rapidly, returning to the control value by 24 h. Pancreatic insulin levels did not decrease significantly until 24 h. Exposure of isolated rat islets to CPH for 30 min in vitro selectively inhibited proinsulin synthesis by 62%, without affecting preproinsulin mRNA levels. The dissociation between changes in proinsulin and preproinsulin mRNA levels suggests that the decrease in preproinsulin mRNA in vivo is associated with but does not cause CPH-induced changes in insulin biosynthesis.

Actins↗
PubMed1991

Protective effect of a high protein diet against the toxicity of some organophosphorus compounds in albino rats.

The present investigation deals with determining the efficacy of a high protein diet (HPD) in combating toxicity in albino rats of some organophosphorus compounds (OPCs) that follow dissimilar metabolic patterns in a living system. As assessed by an increase or decrease in the levels of some biochemical and nutritional parameters, the high protein diet containing 59% protein seems to have a beneficial effect in alleviating toxicity of low but prolonged doses of OPCs over the standard diet (SD) containing 19% protein. OPCs undergoing direct detoxication in a living system like diisopropyl phosphoro-fluoridate (DFP) appear to be more susceptible to HPD than those undergoing biotoxication like EPN (O-ethyl O-p-nitrophenyl phenyl-phosphonothioate) and malathion (S-(1,2-dicarbethoxyethyl) O,O-dimethyldithiophosphate).

Alanine Transaminase↗
PubMed1991

High altitude dives from 7000 to 14,200 feet in the Himalayas.

Indian Navy divers carried out no-decompression dives at altitudes of 7000 to 14,200 ft (2134-4328 m) in the Nilgiris and Himalayas from May to July 1988. Seventy-eight dives on air and 22 dives on oxygen were carried out at various altitudes. The final dives were at Lake Pangong Tso (4328 m) in Ladakh, Himalayas, to a maximum of 140 feet of sea water (fsw) [42.6 meters of sea water (msw)] equivalent ocean depth in minimum water temperature of 2 degrees C. Oxygen diving at 14,200 ft (4328 m) was not successful. Aspects considered were altitude adaptation, diminished air pressure diving, hypothermia, and remote area survival. Depths at altitude were converted to depths at sea level and were applied to the Royal Navy air tables. Altitude-related manifestations, hypoxia, hypothermia, suspected oxygen toxicity, and equipment failure were observed. It is concluded that stress is due to effects of altitude and cold on man and equipment, as well as changes in diving procedures when diving at high altitudes. Equivalent air depths when applied to Royal Navy tables could be considered a safe method for diving at altitudes.

Acclimatization↗
PubMed1990

DNA analysis by flow cytometry in malignant pleural mesothelioma: relationship to histology and survival.

In a retrospective study of 70 patients with malignant pleural mesothelioma, 168 formalin-fixed, paraffin-embedded tumour specimens were examined for DNA content by flow cytometry. In 20 patients where two or more blocks of the same tumour were available, there was considerable agreement between ploidy status and S-phase percentage in the different specimens. There were no significant differences for survival for patients who had been exposed to asbestos and those in whom no exposure could be elicited, nor for aneuploid and diploid tumours. The S-phase content was examined for different areas of the same tumour and the percentages were largely in agreement. However, those patients who had tumours with an S-phase percentage greater than the median (6 per cent) had a significantly shorter survival than those with tumours of lower S-phase percentage. Differences in DNA content and other cell cycle parameters were not associated with the histological subtypes.

Aged↗
PubMed1990

Malignant pleural mesothelioma and epidermal growth factor receptor (EGF-R). Relationship of EGF-R with histology and survival using fixed paraffin embedded tissue and the F4, monoclonal antibody.

The expression of epidermal growth factor receptor (EGF-R) in 34 formalin fixed paraffin embedded specimens of malignant mesothelioma was examined using the F4 antibody. Eight samples of reactive pleura showed homogenous cytoplasmic staining with the antibody. EGF-R positive cells (greater than or equal to 5%) were found in 68% of the mesotheliomas examined. EGF-R positivity was more commonly seen in the epithelial histological subtype than in the sarcomatous or mixed subtypes. Patients with less than 5% of mesothelioma cells staining positive for EGF-R had a significantly shorter survival (median 299 days) compared with patients whose tumours had a greater number of cells positive for EGF-R (median 446 days) (P = 0.04). However, when the histological subgroup was also taken into consideration (epithelial type had a significantly longer survival than the sarcomatous or mixed) the survival difference in relation to EGF-R positivity was no longer significant (P = 0.08). EGF-R could not be used to distinguish between malignant and benign mesothelial tissue and was not an independent prognostic factor for survival.

Adult↗
PubMed1990

Contact depigmentation from free para-tertiary-butylphenol in bindi adhesive.

100 consecutive cases of contact depigmentation due to bindi during a period of 11 months were studied. Bindi adhesive material was found to contain 80% para-tertiary-butylphenol (PTBP), by thin-layer chromatography, infrared spectrophotometry and high-pressure liquid chromatography. The possibility of hypersensitivity to PTBP was ruled out as none of the 15 patients tested with 2% PTBP and 1% para-tertiary-butylphenol-formaldehyde resin gave any positive reactions. Development of depigmentation could have been due either to individual susceptibility or to constant use for a prolonged period. The area of contact being very small, generalised vitiligo as a result of systemic absorption appeared to be a remote possibility.

Adhesives↗
PubMed1990

Characterization of transposon insertion out- mutants of Erwinia carotovora subsp. carotovora defective in enzyme export and of a DNA segment that complements out mutations in E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Erwinia chrysanthemi.

Soft-rotting Erwinia spp. export degradative enzymes to the cell exterior (Out+), a process contributing to their ability to macerate plant tissues. Transposon (Tn5, Tn10, Tn10-lacZ) insertion Out- mutants were obtained in Erwinia carotovora subsp. carotovora 71 by using plasmid and bacteriophage lambda delivery systems. In these mutants, pectate lyases, polygalacturonase, and cellulase, which are normally excreted into the growth medium, accumulated in the periplasm. However, localization of the extracellular protease was not affected. The Out- mutants were impaired in their ability to macerate potato tuber tissue. Out+ clones were identified in a cosmid library of E. carotovora subsp. carotovora 71 by their ability to complement mutants. Localization of cyclic phosphodiesterase in the periplasm indicated that the Out+ plasmids did not cause lysis or a nonspecific protein release. The Out+ derivatives of the E. carotovora subsp. carotovora 71 mutants regained the ability to macerate potato tuber tissue. Our data indicate that a cluster of several genes is required for the Out+ phenotype. While one plasmid, pAKC260, restored the Out+ phenotype in each of the 31 mutants of E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Erwinia chrysanthemi, it failed to render Escherichia coli export proficient. Homologs of E. carotovora subsp. carotovora 71 out DNA were detected by Southern hybridizations in subspecies of E. carotovora under high-stringency conditions. In contrast, E. chrysanthemi sequences bearing homology to the E. carotovora subsp. carotovora 71 out DNA were detectable only under low-stringency hybridization. Thus, although the out genes are functional in these two soft-rotting bacterial groups, the genes appear to have diverged.

Biological Transport↗
PubMed1990

Molecular cloning and characterization of an Erwinia carotovora subsp. carotovora pectin lyase gene that responds to DNA-damaging agents.

recA-mediated production of pectin lyase (PNL) and the bacteriocin carotovoricin occurs in Erwinia carotovora subsp. carotovora 71 when this organism is subjected to agents that damage or inhibit the synthesis of DNA. The structural gene pnlA was isolated from a strain 71 cosmid gene library following mobilization of the cosmids into a moderate PNL producer, strain 193. The cosmid complemented pnl::Tn5 but not ctv::Tn5 mutations. A constitutive level of PNL activity was detected in RecA+ and RecA- Escherichia coli strains carrying the pnlA+ gene on the high-copy-number plasmid pBluescript SK-. Mappings of Mu dI1734 (Km lac'ZYA) insertions in pnlA and unidirectional deletion analyses allowed localization of the gene to approximately 1.4 kilobases of DNA. A typical pnlA-lacZ transcriptional fusion was inducible in a RecA+ but not a RecA- derivative of strain 71. In contrast, the pnlA-lacZ fusion was not inducible in a RecA+ E. coli strain. DNA sequences homologous to pnlA were detected in E. carotovora subsp. carotovora and E. carotovora subsp. atroseptica strains and in one of four Erwinia rhapontici strains but not in Erwinia chrysanthemi.

Chromosome Mapping↗
PubMed1989

Hormone mediated changes of brain glutamic acid system in amino acid imbalance.

The effects of adrenal cortical hormone and thyroxine on brain glutamic acid, gamma-amino butyric acid (GABA) and glutamine were studied in rats fed on the amino acid imbalanced diet (8% casein diet supplemented with 0.3% L-threonine). The studies revealed that the decrease in brain glutamic acid and GABA levels in threonine imbalance was recovered by hydrocortisone supplementation. The increased level of brain glutamine in threonine imbalance could not, however, be reversed by hydrocortisone supplementation. Thyroxine supplementation was found to have no impact on any of the members of glutamic acid family in the brain of rats receiving the threonine-imbalanced diet. It was suggested that the decreased levels of brain glutamic acid and GABA in threonine imbalance were caused by diminished adrenal cortical function and the influence of adrenal cortical hormone could be suggested to reside at the level of formation of both glutamic acid and GABA.

Adrenal Cortex↗
PubMed1989

Pneumoconiosis in pottery workers and its trends in north Staffordshire from the point of view of the Medical Boarding Centre (Respiratory Diseases), Stoke-on-Trent.

Classification of pottery workers' pneumoconiosis and the procedure followed for claims to disablement benefit for this condition have been outlined. Review of the newly diagnosed cases of pneumoconiosis in pottery workers in North Staffordshire as experienced by the Medical Boarding Centre (Respiratory Diseases), Stoke-on-Trent, show that the number of such cases has dropped from the peaks of nearly 300 cases per year in the mid-1950s to about 10 cases per year in the last 12 years. The percentage of people aged 60 and above among the newly diagnosed cases has increased from 35% in the 1960s to about 70% in the 1980s. Only a minority of cases has been diagnosed following exposure under 20 years and most described exposure for over 30 years. As a point of interest, age at death of not strictly comparable groups of pottery workers at different times over the last 100 years has been compared. The longevity, probably not surprisingly, appears to have improved considerably during that period. Although our data do not denote the true incidence of pneumoconiosis in pottery workers in North Staffordshire perhaps it may be concluded that our figures do point to a declining incidence of this condition.

Adult↗
PubMed1988

Different effects of growth hormone on growth and function of isolated adult and fetal rat pancreatic islets.

We simultaneously determined 3H-thymidine incorporation, DNA content, and insulin biosynthesis in adult and fetal rat pancreatic islets. 3H-thymidine incorporation was measured after tissue solubilization. DNA was measured fluorometrically. Insulin biosynthesis was determined through 3H-leucine incorporation after immunoprecipitation and binding to protein A-sepharose. Addition of growth hormone caused a significant increase in 3H-thymidine incorporation into both the adult and the fetal islets, but only the adult islets experienced an increase in DNA content. The increase in 3H-leucine incorporation was also significant only in the adult islets. The dynamics of 3H-thymidine incorporation after growth hormone administration were different in the adult and the fetal pancreas. Fetal islets have the potential to increase their incorporation of 3H-thymidine, but very limited potential for insulin biosynthesis.

Animals↗