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Biomedical subjects

A Chatterjee

Publications and source records attributed to A Chatterjee.

At least 235 records · Page 13Linked to original sources
PubMed1994

Nucleotide sequence, organization and expression of rdgA and rdgB genes that regulate pectin lyase production in the plant pathogenic bacterium Erwinia carotovora subsp. carotovora in response to DNA-damaging agents.

In most soft-rotting Erwinia spp., including E. carotovora subsp. carotovora strain 71 (Ecc71), production of the plant cell wall degrading enzyme pectin lyase (Pnl) is activated by DNA-damaging agents such as mitomycin C (MC). Induction of Pnl production in Ecc71 requires a functional recA gene and the rdg locus. DNA sequencing and RNA analyses revealed that the rdg locus contains two regulatory genes, rdgA and rdgB, in separate transcriptional units. There is high homology between RdgA and repressors of lambdoid phages, specially phi 80. RdgB, however, has significant homology with transcriptional activators of Mu phage. Both RdgA and RdgB are also predicted to possess helix-turn-helix motifs. By replacing the rdgB promoter with the IPTG-inducible tac promoter, we have determined that rdgB by itself can activate Pnl production in Escherichia coli. However, deletion analysis of rdg+ DNA indicated that, when driven by their native promoters, functions of both rdgA and rdgB are required for the induction of pnlA expression by MC treatment. While rdgB transcription occurs only after MC treatment, a substantial level of rdgA mRNA is detected in the absence of MC treatment. Moreover, upon induction with MC, a new rdgA mRNA species, initiated from a different start site, is produced at a high level. Thus, the two closely linked rdgA and rdgB genes, required for the regulation of Pnl production, are expressed differently in Ecc71.

Amino Acid Sequence↗
PubMed1994

Nucleotide sequence and expression of a novel pectate lyase gene (pel-3) and a closely linked endopolygalacturonase gene (peh-1) of Erwinia carotovora subsp. carotovora 71.

Our previous genetic analysis (J. W. Willis, J. K. Engwall, and A. K. Chatterjee, Phytopathology 77:1199-1205, 1987) had revealed a tight linkage between pel-3 (pel, pectate lyase gene) and peh-1 (peh, polygalacturonase gene) within the chromosome of Erwinia carotovora subsp. carotovora 71. Nucleotide sequencing, transcript assays, and expression of enzymatic activities in Escherichia coli have now confirmed that a 3,500-bp segment contains the open reading frames (ORFs) for Pel-3 and Peh-1. The 1,041-bp pel-3 ORF and the 1,206-bp peh-1 ORF are separated by a 579-bp sequence. The genes are transcribed divergently from their own promoters. In E. coli and E. carotovora subsp. carotovora 71, peh-1 is better expressed than pel-3. However, plant signals activate the expression of both the genes in E. carotovora subsp. carotovora. A consensus integration host factor (IHF)-binding sequence upstream of pel-3 appears physiologically significant, since pel-3 promoter activity is higher in an E. coli IHF+ strain than in an IHF- strain. While peh-1 has extensive homology with plant and bacterial peh genes, pel-3 appears not to have significant homology with the pel genes belonging to the pelBC, pelADE, or periplasmic pel families. Pel-3 also is unusual in that it is predicted to contain an ATP- and GTP-binding site motif A (P-loop) not found in the other Pels.

Amino Acid Sequence↗
PubMed1994

Regulation of the production of extracellular pectinase, cellulase, and protease in the soft rot bacterium Erwinia carotovora subsp. carotovora: evidence that aepH of E. carotovora subsp. carotovora 71 activates gene expression in E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Escherichia coli.

The production of pectolytic enzymes (pectate lyase [Pel] and polygalacturonase [Peh]), cellulase (Cel), and protease (Prt) is activated in the soft rot bacterium Erwinia carotovora subsp. carotovora by aepA (activator of extracellular protein production) and celery extract (Y. Liu, H. Murata, A. Chatterjee, and A. K. Chatterjee, Mol. Plant-Microbe Interact. 6:299-308, 1993). We recently isolated a new class of mutants of strain E. carotovora subsp. carotovora 71 which overproduces Pel, Peh, Cel, and Prt. From the overproducing strain AC5034, we identified an activator locus, designated aepH*, which stimulated Pel, Peh, Cel, and Prt production in E. carotovora subsp. carotovora 71 or its derivatives. The nucleotide sequence of the aepH* DNA segment revealed an open reading frame of 141 bp that could encode a small (5.45-kDa) highly basic (pI 11.7) protein of 47 amino acid residues. Analyses of deletions and MudI insertions indicated that the activator function required the 508-bp DNA segment which contains this open reading frame. The wild-type locus, aepH+, is localized within a DNA segment upstream of aepA. An AepH- strain constructed by exchanging aepH+ with aepH*::MudI was deficient in Pel, Peh, Cel, and Prt production; exoenzyme production was restored upon the introduction of a plasmid carrying aepH+ or aepH*. Plasmids carrying either aepH+ or aepH* activated the production of Pel-1, Peh-1, and Cel in Escherichia coli HB101 carrying the cognate genes. The aepH effect in E. coli was due to the activation of transcription, as indicated by assays of pel-1 and peh-1 mRNAs. The aepH+ and aepH* plasmids also stimulated Pel, Peh, Cel, and Prt production in other wild-type E. carotovora subsp. carotovora strains as well as in E. carotovora subsp. atroseptica. Although the stimulatory effect was generally more pronounced with aepH* than with aepH+, the extent of activation in the wild-type strains depended upon the bacterial strain and the growth medium. Southern blot hybridization revealed the presence of aepH homologs in E. carotovora subsp. carotovora and E. carotovora subsp. atroseptica, and provided physical evidence for linkage between aepA and aepH homologs in genomes of these bacteria. We conclude that aepH-mediated activation of exoprotein gene expression is a feature common to most strains of E. carotovora.

Amino Acid Sequence↗
PubMed1994

Picturing unilateral spatial neglect: viewer versus object centred reference frames.

Vision theorists postulate that knowledge of objects in space is shaped by different spatial coordinate systems. An object may be represented by its location in relation to the viewer, or it may be represented by its own intrinsic spatial properties. When patients with left sided neglect fail to respond to stimuli on the left, it is not clear whether "left" refers to a viewer or an object centred reference frame. To uncouple these two reference frames, eight patients with neglect were asked to centre lines and objects in photographs. Viewer centred neglect would result in images appearing on the right side of photographs and object centred neglect would result in images appearing on the left. Four patients demonstrated viewer centred neglect and three demonstrated object centred neglect. One patient had variable performance, perhaps resulting from competing effects of both viewer and object centred neglect. Stimuli characteristics did not affect the spatial coordinate system in which neglect occurred. These results suggest that viewer centred and object centred reference frames are functionally dissociable, and that patients may have spatial neglect predominantly in either coordinate system.

Aged↗
PubMed1994

Ventricular late potentials after thrombolysis.

High frequency low amplitude signals that prolong the terminal portion of the QRS complex in the electrocardiogram are termed late potentials (LPs). It has been established for quite some time that the presence of LPs after acute myocardial infarction (AMI) is associated with an increased risk of ventricular tachyarrythmias and sudden cardiac death (SCD), and vice versa. It is also known that thrombolytic therapy after AMI significantly decreased the incidence of ventricular tachyarrythmias and SCD. The object of this study was to find out whether thrombolysis in AMI decreased the incidence of LPs. Fifty two male patients of the age group 41-46 years with first anterior wall AMI were studied. Thirty of them presented within 6 hours of chest pain and were given intravenous streptokinase (IVSK) in addition to conventional therapy. The remaining 22 received conventional therapy but no thrombolysis. There was no significant difference in these two groups regarding age, CKMB, hypertension, diabetes, smoking, prior use of beta blockers, and ejection fraction. Eight out of the 30 patients receiving IVSK were positive for LPs as against 13 out of the 22 in the control group. This difference was statistically significant (p > 0.02 < 0.01). Thus thrombolysis in the early hours of anterior AMI diminishes the incidence of LPs.

Adult↗
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↗
PubMed1994

Actinobacillus pleuropneumoniae in gnotobiotic piglets: ultrastructural changes in the pulmonary alveoli with dose and time.

The ultrastructural changes in pulmonary alveoli produced by transtracheal inoculation of 10(6) and 10(8) CFU of Actinobacillus pleuropneumoniae serotype 5 in gnotobiotic piglets were studied after 1 and 4 h. At 1 h postinoculation (p.i.) with 10(6) or 10(8) CFU, no gross change in lung and no evidence of infiltration of cells into alveoli was observed. At 4 h p.i., at a dose of 10(6) CFU, a generalized red mottling occurred in the dorsal half of the caudal lobe, which revealed ultrastructural evidence of neutrophil infiltration into alveoli along with fibrin and a few erythrocytes. At 4 h p.i., at a dose of 10(8) CFU, there was a bilateral lung lesion characterized by a generalized mottling and congestion, within which we observed ultrastructural evidence of bacteria and cellular debris in the alveoli and fibrin clots and cellular necrosis in the alveolar septum. By using gnotobiotic piglets and visualizing the effects of bacterial inoculum on cellular ultrastructure of the lung, we have demonstrated that both dose and time play roles in the early pathogenesis of experimental porcine pleuropneumonia. The developing lesion in lungs of gnotobiotic piglets infected with pure cultures of A. pleuropneumoniae can be controlled experimentally. This experimental procedure can provide a base of reproducible, sequential, ultrastructural changes with which to compare the role of inflammatory mediators in the lung and the effects of drugs on immunologic events in the lung.

Actinobacillus Infections↗
PubMed1993

Genetic and physical mapping of the biglycan gene on the mouse X chromosome.

A human cDNA for biglycan (BGN) has recently been mapped to proximal Xq28. We have mapped the murine locus, Bgn, approximately 50 kb distal to DXPas8, using a combination of genetic mapping in an interspecific backcross of B6CBA-Aw-J/A-Bpa x Mus spretus and physical mapping using pulsed field gel electrophoresis and analysis of murine yeast artificial chromosomes (YACs) containing both DXPas8 and Bgn. Our mapping studies also appear to exclude Bgn as a candidate gene for the bare patches (Bpa) mutation and for the homologous human disorder X-linked dominant chondrodysplasia punctata (CDPX2).

Animals↗
PubMed1993

Protective effect of cysteine against X-ray- and bleomycin-induced chromosomal aberrations and cell cycle delay.

The protective effect of cysteine was studied in muntjac and human lymphocytes in vitro scoring chromosomal aberrations in harlequin stained first cycle metaphases, induced by X-irradiation at G0. Its protective efficiency was also studied against the radiomimetic clastogen, bleomycin, in muntjac cells. 30 micrograms and 1 mg/ml of cysteine were given prior to 2, 3, and 4 Gy, and 2 mg/ml prior to only 4 Gy. 30 micrograms cysteine protected only against deletions in 4 Gy-treated cells while 1 mg protected against deletions by all three doses of X-rays. However, rearrangements were not reduced significantly in any of these, probably due to their low frequency. But when cysteine was increased to 2 mg, both types of aberrations were reduced significantly. This shows that a sufficient number of aberrations and an optimum concentration of the protector are essential for eliciting the best protective effect. This conclusion is further supported by the results of 2 mg cysteine treatment in human lymphocytes which yielded higher frequencies of rearrangements with 2 and 3 Gy X-rays than 4 Gy in muntjac, but had a relatively lower frequency of deletions. Thus the most abundant categories of aberration, i.e., deletions in muntjac and exchanges in humans, were reduced significantly by 2 mg cysteine, associated with a prominent reduction in the frequency of aberrant metaphases. Therefore, the differential protection observed with a low concentration of the protector and an insufficient yield of aberrations induced only indicates protection provided to the most frequent type of aberration by a protector when present in lower concentration. Cysteine pretreatment yielded weak protection against the effects of bleomycin, but posttreatment caused a mild potentiation of the clastogenic effect of BLM without altering the cell cycle kinetics. In this context, an action of cysteine as a reducing agent on BLM is suggested. Although cysteine alone caused severe retardation of the cell cycle, when given prior to X-irradiation, not only its delaying effect was not observed, but also it reduced the X-ray-induced cell cycle delay. This might be due to the oxidation of cysteine by its radical scavenging action.

Animals↗
PubMed1993

A study of ground water contamination by arsenic in the residential area of Behala, Calcutta due to industrial pollution.

Due to the discharge of industrial effluent after production of the insecticide Paris-Green [Copper acetoarsenite Cu(CH(3)COO)(2).3Cu(AsO(2))(2)] by a local factory at the P. N. Mitra Lane, Behala, ground water has become contaminated with arsenic. More than seven thousand people were using this arsenic contaminated tube-well water for drinking and house-hold purposes. Many people of the area were hospitalised and symptoms of arsenic toxicity were visible amongst a large number of the population. Analytical study reveals that soil around the area of effluent dumping point, which is at the middle of the locality, contains a very high concentration of arsenic and copper. For the last 20 years this factory had been producing 20 tons of Paris-Green per year and had been dumping its effluent in that area. It seems, the effluent treatment for arsenic removal was not adequate and finally arsenic percolated to the underground aquifers. Consequently, arsenic concentration in the ground water is very high. Both arsenite and arsenate are present in ground water. An alternate source of water other than the ground water is immediately necessary for the people of P. N. Mitra Lane.

Journal Article↗
PubMed1993

Computer simulation of initial events in the biochemical mechanisms of DNA damage.

Understanding the systematic and quantitative correlation between the physical events of energy deposition by ionizing radiation and the ensuing chemical and biochemical processes leading to DNA damage is one of the goals in radiation research. Significant progress has been made toward achieving the stated goal by using theoretical modeling techniques. These techniques are strongly dependent on computer simulation procedures. A review of such techniques with details of various stages of simulation development, including a comparison with available experimental data, is presented in this article.

Base Sequence↗
PubMed1993

Concordance between observers in descriptions of personality change in Alzheimer's disease.

To evaluate observer bias and to estimate observer concordance for descriptions of personality changes in dementia, the authors examined the personality descriptions of dementia patients provided by 2 informants. Twenty-two patients with Alzheimer's disease were rated on the NEO-PI by each of 2 informants, the primary caregiver and another relative or friend. Each informant completed the NEO-PI to describe current behavior and premorbid behavior. Significant differences between premorbid and current descriptions were found for 4 of the 5 personality dimensions measured. There was substantial agreement between independent raters, as indicated by significant correlations between raters for 4 dimensions and the absence of significant differences between rater averages. These results suggest that both primary caregivers and others who know a patient well may serve as informants for studies of personality in dementia.

Aged↗
PubMed1993

Cholinergic treatment of an amnestic man with a basal forebrain lesion: theoretical implications.

Cholinergic deficient states, such as in Alzheimer's disease, are associated with amnesia. Therapeutic trials with cholinergic augmentation in Alzheimer's disease have had only equivocal results, but mechanisms other than cholinergic deficiency may contribute to the memory deficit. Normally the diagonal band of Broca provides much of the hippocampal cholinergic input. To learn if amnesia secondary to cholinergic deficiency can be ameliorated by cholinergic augmentation, we treated an amnestic man who had a lesion located primarily in the right diagonal band of Broca with physostigmine and lecithin. During the initial best-dose-finding phase, he demonstrated an inverted U-shaped curve for immediate recall of word lists, with peak performances at 3.0 and 3.5 mg of physostigmine. Single photon emission tomography showed decreased blood flow in the medial temporal region ipsilateral to the lesion at baseline, with a reversal of the asymmetry on 3.5 mg of physostigmine. A follow-up double-blind, placebo-controlled study on 3.5 mg of physostigmine, however, failed to demonstrate that cholinergic treatment improved memory.

Amnesia↗
PubMed1993

Filarial nephritis: a cause of nephrotic syndrome.

A 26-year-old male presented with oedema, massive albuminuria and microscopic haematuria. Kidney biopsy revealed enlarged cellular glomeruli infiltrated by polymorphs and eosinophils with focal fibrin deposits along the basement membrane. Microfilariae were seen in the lumen of few glomerular capillaries. Antistreptolysin titre was negative. The absence of other aetiological factors and presence of microfilariae within glomeruli suggests that nephrotic syndrome may be due to a filarial nephritis.

Adult↗
PubMed1993

Maternal deaths--a ten-year study.

In a 10-year retrospective study of maternal deaths at RG Kar Medical College, Calcutta there were 651 maternal deaths with 410 in first 5-year period and 241 in second 5-year period. The leading causes of deaths were due to abortion, toxaemia, haemorrhage (antepartum and postpartum) and jaundice in pregnancy. Direct causes were responsible for death in 77.6% cases, indirect causes in 17.5% cases and unrelated causes in 4.9% cases. Majority (557) were unbooked and mostly multigravida (434) cases. Most of them (251) were in the age group of 20-25 years. Haemorrhage was the single most common cause to claim 188 lives. It was also noted that 155 deaths occurred within 12 hours of hospital admission.

Adult↗