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Biomedical subjects

A Chatterjee

Publications and source records attributed to A Chatterjee.

At least 19 recordsLinked to original sources
PubMed1995

A comparative transcriptional map of a region of 250 kb on the human and mouse X chromosome between the G6PD and the FLN1 genes.

The transcriptional organization of the region of the mouse X chromosome between the G6pd and the Fln1 genes was studied in detail, and it was compared with the syntenic region of the human chromosome. A cosmid contig of 250 kb was constructed by screening mouse cosmid libraries with probes for human genes and with whole cosmids. Overlapping cosmids were aligned by comparing EcoRI and rare-cutter restriction enzyme digestions. The gene order and the orientation of transcription were determined by hybridization with fragments from the 5' and 3' moieties of each cDNA. Our work demonstrates that all of the new genes identified in human are present in the mouse. The size of the region, 250 kb, is also very similar, as are gene order and gene organization: the transcriptional organization in "domains" described in human is found to be identical in the mouse. The major difference detected is the much lower content in rare-cutter restriction sites, which is related to the lower G+C and CpG content of mouse DNA. The very high conservation that we have described suggests that a potent selective pressure has contributed to such conservation of gene organization.

Animals↗
PubMed1995

Agrammatic sentence production: the use of a temporal--spatial strategy.

We report the sentence production of a left-handed man with a right-hemisphere infarct. He demonstrated an inability to correctly map grammatical categories (subject, object) onto thematic roles (agent, patient) even for simple active sentences. The patient's performance appears to be the result of selective damage to the functional level (Garrett, 1980) of sentence production. His failure could not be accounted for by theories of agrammatism that implicate memory deficits, phonologic processing impairments, or deficits in processing complex transformations. The patient's performance revealed the consistent application of a temporal-spatial strategy in sentence production, despite adequate lexical-semantic abilities.

Aged↗
PubMed1995

Asyntactic thematic role assignment: the use of a temporal-spatial strategy.

We report syntactic comprehension performance of a left-handed man with a right-hemisphere infarct. He was unable to accurately map grammatical categories (subject, object) onto thematic roles (agent, patient), despite demonstrating intact conceptual knowledge of these thematic roles. He performed poorly on both active and passive reversible sentences. His asyntactic thematic role assignment cannot be accounted for by a short-term memory impairment or any hypothesis that predicts selective vulnerability to passive sentence constructions. Rather than performing randomly, our patient used a temporal or spatial strategy in assigning thematic roles. Because he also had a production-mapping deficit and used the same temporal-spatial strategy in production tasks, we hypothesize that the mapping of thematic roles onto grammatical categories and vice versa may be a specific aspect of sentence processing that is common to sentential production and comprehension. We also raise the possibility that thematic roles have underlying spatial representations prior to being elaborated by grammar.

Aged↗
PubMed1995

Effect of glutathione on sister-chromatid exchanges in normal and buthionine sulfoximine-treated mice.

Based on their ability to induce sister-chromatid exchanges (SCEs) it is evident that thiol-containing radioprotectors can induce DNA damage. However, there were contradictory findings when reduced glutathione (GSH) was tested using two cell lines. The present study demonstrated that GSH can induce SCEs and also delay in cell proliferation in mouse bone marrow cells in vivo. The presence of catalase significantly reduced GSH-induced SCE frequency down to catalase alone levels. An attempt was made to evaluate the effect of GSH treatment in buthionine sulfoximine (BSO)-treated mice (GSH-depleted mice) and the data indicate that induction of SCEs takes place without inducing a delay in cell proliferation or the generation of hydrogen peroxide. Probably, some unknown route is involved by which GSH-degraded product(s) induce SCEs in BSO-treated mice. Therefore, the induction of SCEs by GSH in normal mice may be largely due to hydrogen peroxide generation; however, the involvement of the binding ability of GSH to chromatin and the probable (unknown) route by which GSH-degraded product(s) may cause smaller fraction of SCEs cannot be ruled out.

Animals↗
PubMed1995

Spatial characteristics of thematic role representation.

Humans use language to describe actions by mapping the thematic roles of agent (doer of actions) and patient (recipient of actions) on the grammatical categories of subject and object. The extent to which thematic roles can be conceptualized independent of language is not known. If nonlinguistic conceptualization of thematic roles is possible, then representation of these roles would evidence nonlinguistic characteristics. Motivated by observations in an aphasic man, we wished to learn if thematic roles are conceptualized spatially. Normally subjects were asked to draw stick figures depicting the thematic roles of agent and patient. They demonstrated a systematic spatial bias in locating agents to the left of where they located patients. This bias, somewhat mitigated by ordering effects of motor output and auditory input, was brought into clearest focus when subjects depicted thematic roles in a context stripped of surface sentential form. These data imply that, in their nascent form, the thematic roles of agent and patient are spatially represented prior to being projected on grammar.

Adult↗
PubMed1995

Arsenic in ground water in six districts of West bengal, India: the biggest arsenic calamity in the world. Part 2. Arsenic concentration in drinking water, hair, nails, urine, skin-scale and liver tissue (biopsy) of the affected people.

In six districts of West Bengal arsenic has been found in ground water above the maximum permissible limit recommended by the WHO of 0.05 mg l-1. This water is used by the villagers for drinking, cooking and other household purposes. These six districts have an area of 34,000 km2 and hold a population of 30 million. Over the last five years we have surveyed only a few small areas of these six affected districts and our survey revealed that, at present, at least 800,000 people from 312 villages in 37 blocks are drinking contaminated water and more than 175,000 people are showing arsenical skin lesions that are the late stages of manifestation of arsenic toxicity. Most of the three stages of arsenic-related clinical manifestations are observed amongst the affected people. The common symptoms are conjunctivitis, melanosis, depigmentation, keratosis and hyperkeratosis; cases of gangrene and malignant neoplasms are also observed. The source of arsenic is geological. We have analysed thousands of arsenic contaminated water samples. Most of the water samples contain a mixture of arsenite and arsenate and in none of them could we detect methylarsonic or dimethylarsenic acid. We have also analysed a large number of urine, hair and nail samples, several skin-scales and some liver tissues (biopsy samples) of the people drinking the arsenic contaminated water and showing arsenical skin lesions. Flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) was used for the analysis of hair, nails, urine and skin-scale after decomposition by various techniques. The liver tissues were analysed by Zeeman corrected-ETAAS using a few milligrams of the biopsy samples.

Adolescent↗
PubMed1995

Cross-over, completion and confabulation in unilateral spatial neglect.

Patients with left-sided neglect generally mis-bisect horizontal lines to the right of mid-position. However, with short lines they frequently cross over and place their marks to the left; a phenomenon not easily explained by current theories of neglect. It is difficult to ascertain whether patients neglect the ipsilateral segment of short lines, perceptually distort these lines, or extend these lines leftward at a representational level. Reading horizontally arrayed letter strings is an alternative task potentially capable of sorting between these hypotheses, providing this task could be demonstrated to be comparable to line bisections. In this study, we exploit the observation that line bisection performance may be described by a power function: psi = K phi beta, in which psi represents the subjective awareness of lines and the objective measurements of these lines. The constant and exponent are empirically derived. We have investigated whether reading task performance also subscribes to power functions. Five patients with left-sided neglect were tested on line bisections and reading tasks with stimuli of varying horizontal lengths. Performance on both tasks could be described by power functions and patients were similarly ordered by severity across both tasks. Since power function analyses established that these tasks were comparable, reading performance on short words provided insight into how patients bisected short lines. Patients reported additional letters to the left end of short words suggesting that cross-over bisections are analogously a consequence of completion or confabulation of short lines beyond their objective left end-point. Although most neglect patients have difficulties forming veridical left-sided representations, this cross-over phenomenon is interpreted as resulting from a lack of inhibition of leftward confabulatory mental representations. Since both bisections and reading tasks are described by a continuous function, it is proposed that similar lack of inhibition must also be present, albeit hidden, when patients confront stimuli with longer lateral extension. Confabulatory phenomena at the left edge of these patients' rightwardly constricted attentional window, may be far more common than hitherto appreciated.

Aged↗
PubMed1995

Inactivation of rsmA leads to overproduction of extracellular pectinases, cellulases, and proteases in Erwinia carotovora subsp. carotovora in the absence of the starvation/cell density-sensing signal, N-(3-oxohexanoyl)-L-homoserine lactone.

The soft-rotting bacterium, Erwinia carotovora subsp. carotovora 71, produces extracellular enzymes such as pectate lyase isozymes (Pels), cellulase (Cel), polygalacturonase (Peh), and protease (Prt). While the extracellular levels of these enzymes are extremely low when the bacterium is grown in salts-yeast extract-glycerol (SYG) medium, the enzymatic activities are highly induced in SYG medium supplemented with celery extract. By transposon (mini-Tn5) mutagenesis, we isolated a RsmA- mutant, AC5070, which overproduces extracellular enzymes; the basal levels of Pel, Peh, and Cel in AC5070 are higher than the induced levels in the RsmA+ parent, AC5047. While Peh production is mostly constitutive in AC5070, Pel, Cel, and Prt production is still inducible with celery extract. The high basal levels of pel-1, pel-3, and peh-1 mRNAs in AC5070 demonstrate that overproduction of the pectolytic enzymes is due to the stimulation of transcription. Using chromosomal DNA flanking mini-Tn5 as a probe, we cloned the wild-type rsmA+ allele, which suppresses Pel, Peh, Cel, and Prt production in both RsmA+ and RsmA- strains. The RsmA- mutant, like its parent, produces N-(3-oxohexanoyl)-L-homoserine lactone (HSL), a starvation/cell density-sensing signal required for extracellular enzyme production. To examine the role of HSL, we constructed HSL-deficient strains by replacing hslI, a locus required for HSL production, with hslI::Tn3HoHo1-Spc. While the basal levels of Pel, Peh, Cel, and Prt are comparable in the RsmA- mutant and its HSL- derivative, these enzymes are barely detectable in the Hsl- derivative of the RsmA+ parent strain.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Butyrolactone↗
PubMed1995

Identification of a global repressor gene, rsmA, of Erwinia carotovora subsp. carotovora that controls extracellular enzymes, N-(3-oxohexanoyl)-L-homoserine lactone, and pathogenicity in soft-rotting Erwinia spp.

The production of extracellular enzymes such as pectate lyase (Pel), polygalacturonase (Peh), cellulase (Cel), and protease (Prt) is activated by the cell density (quorum)-sensing signal, N-(3-oxohexanoyl)-L-homoserine lactone (HSL); plant signals; and aep genes during postexponential growth of Erwinia carotovora subsp. carotovora 71. Studies with mutants of E. carotovora subsp. carotovora 71 derepressed in exoenzyme production led to the identification of a negative regulator gene, rsmA (rsm, repressor of secondary metabolites). Nucleotide sequencing, transcript assays, and protein analysis established that a 183-bp open reading frame encodes the 6.8-kDa RsmA. rsmA has extensive homology with the csrA gene of Escherichia coli, which specifies a negative regulator of carbon storage. Moreover, the suppression of glycogen synthesis in E. coli by rsmA indicates that the Erwinia gene is functionally similar to csrA. Southern hybridizations revealed the presence of rsmA homologs in soft-rotting and non-soft-rotting Erwinia spp. and in other enterobacteria such as Enterobacter aerogenes, E. coli, Salmonella typhimurium, Shigella flexneri, Serratia marcescens, and Yersinia pseudotuberculosis. rsmA suppresses production of Pel, Peh, Cel, and Prt, plant pathogenicity, and synthesis of HSL in E. carotovora subsp. atroseptica, E. carotovora subsp. betavasculorum, E. carotovora subsp. carotovora, and E. chrysanthemi. In the E. carotovora subsp. carotovora 71, rsmA reduces the levels of transcripts of hslI, a luxI homolog required for HSL biosynthesis. This specific effect and the previous finding that HSL is required for extracellular enzyme production and pathogenicity in soft-rotting Erwinia spp. support the hypothesis that rsmA controls these traits by modulating the levels of the cell density (quorum)-sensing signal.

4-Butyrolactone↗
PubMed1995

Contribution of lethal mutations to excision assays for tumour cell survival.

Conventional assays of cell survival determine only the proportion of colony-forming cells, assuming that all such cells are equivalent. However, cells surviving irradiation are reported to have lower plating efficiencies than unirradiated controls, suggesting an additional component of cellular damage that is ignored in conventional survival assays, but which could contribute to therapeutic outcome. Therefore we have examined the contribution of this additional form of damage to excision assays for cell survival in experimental tumours following both single dose and fractionated irradiation (10F/5 days) in vivo. Plating efficiencies were considerably lower for the long-term descendents of irradiated compared with non-irradiated cells. Expression of delayed reproductive death was reduced after fractionated radiation doses, only appearing after a substantial number of 3.4 Gy fractions had accumulated. Thus estimates of survival derived from single clonogenicity assays may underestimate the reduction in cell viability from a particular treatment. This could compromise assays for intrinsic radiosensitivity and mathematical modelling of the efficacy of treatment regimens.

Animals↗
PubMed1995

DNA strand breakage is correlated with unaltered base release after gamma irradiation.

Unaltered base release is correlated with strand breakage for gamma-irradiated bacteriophage PM2 DNA in aqueous solution at pH 7.4. The yield of DNA strand breaks is determined by the agarose gel electrophoresis method. High-performance liquid chromatography (HPLC) is used to assay the release of unaltered nucleic bases. Previously reported HPLC methods have been updated. Unaltered base release is linear with dose up to 424 Gy, where up to 0.2% of all DNA bases are released. No detectable amounts of unaltered nucleosides are released and, besides unaltered bases, only one other product released from DNA is observed. Base release yields do not reflect the PM2 GC content of 43%. Only 76% of all prompt strand breaks appear to be associated with the release of an unaltered free base, whereby the guanine, cytosine, adenine and thymine yields are 9, 27, 18 and 22% of the prompt strand break yield, respectively. Postirradiation incubation at 37 degrees C for 24 h increases the strand break yield 1.38-fold and the unaltered base release yield 1.76-fold such that 97% of the final strand breaks appear to be associated with the release of an unaltered base, whereby the guanine, cytosine, adenine and thymine yields are 10, 36, 23 and 28% of the final strand break yield, respectively. These data indicate that, given proper conditions, nearly every strand break leads to a base release. The bearing of these results on OH radical attack leading to strand breakage and base release is discussed.

Bacteriophages↗
PubMed1995

Disposable soft contact lens ulcers: a study of 43 cases seen at Manchester Royal Eye Hospital.

We report an outbreak of 43 episodes of presumed microbial keratitis in 42 disposable soft contact lens wearers seen in the Accident Room of Manchester Royal Eye Hospital during a period of 20 months, and compare this with the general incidence of contact lens-related corneal infection found in a retrospective survey of 6 months' Accident Room attendances during the same period. Thirty-seven patients had worn Acuvue lenses, three had worn Nuvue, and there was no record in two cases. Corneal scrapes were taken for microbiological examination in 27 patients, and 6 of these were culture positive. Conjunctival swabs were taken from eight eyes and one was culture positive. The contact lenses of 11 patients were sent for culture and all grew pathogenic organisms. Pseudomonas spp. were the most common organisms grown, having been found in three of six corneal scrapes and six of 11 contact lens cultures. All affected eyes responded promptly to cessation of contact lens wear and topical antibiotic therapy, with none sustaining severe or permanent visual loss. Reasons for the associated high risk of microbial keratitis are discussed. Thirty-three of the 42 patients responded to a questionnaire regarding lens wear and care and their responses are reported. In consequence, we consider disposable soft contact lenses to be relatively high-risk devices for the cosmetic management of simple myopia, and their continued use must be called into question.

Adolescent↗
PubMed1994

Comparative mapping of the actin-binding protein 280 genes in human and mouse.

Two genes encode actin-binding protein 280 isoforms. ABP-280 or filamin (FLN1) is present in the cytoskeleton of many cell types, whereas expression of FLN2 is limited to skeletal muscle and heart. FLN1 maps to human chromosome Xq28, and, by physical mapping in YAC clones, we have mapped the homologous murine locus (Fln1) to mouse chromosome X, in a region of syntenic homology with human chromosome X. We mapped FLN2 to human chromosome 7q32-q35 by analysis of somatic cell hybrids containing portions of chromosome 7, and, by using a mapping panel from an interspecific murine cross, we mapped the corresponding murine locus (Fln2) to murine chromosome 6 in a region homologous to human chromosome 7.

Animals↗
PubMed1994

A 2.3-Mb yeast artificial chromosome contig spanning from Gabra3 to G6pd on the mouse X chromosome.

A yeast artificial chromosome (YAC) contig of approximately 2.3 Mb has been constructed for the region of the mouse X chromosome between Gabra3 and G6pd. YACs were isolated from four genomic libraries by PCR or hybridization screening for the loci Gabra3, DXHX1104, F8a, DXHX52, DXBay2, L1cam, and Rsvp. Orientation of YACs was performed by isolation of ends using several PCR-based methods, including an adaptation for mouse YAC analysis of interspersed repetitive sequence (IRS)-vector PCR. YAC ends were mapped on a panel of somatic cell hybrids, in an interspecific backcross, using pulsed-field gel (PFG) electrophoresis or by hybridization to other YACs in the contig. Overlapping YACs were further aligned by restriction mapping using rare-cutter restriction endonucleases, as well as by comparison of IRS-PCR fingerprints. This contig represents the largest one assembled to date in the mouse. It should facilitate the isolation of genes in the region and may aid in the completion of a physical contig for the homologous human region, Xq28.

Animals↗