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A Majumder

Publications and source records attributed to A Majumder.

15 recordsLinked to original sources
PubMed2006

Cherenkov radiation from jets in heavy-ion collisions.

The possibility of Cherenkov-like gluon bremsstrahlung in dense matter is studied. We point out that the occurrence of Cherenkov radiation in dense matter is sensitive to the presence of partonic bound states. This is illustrated by a calculation of the dispersion relation of a massless particle in a simple model in which it couples to two different massive resonance states. We further argue that detailed spectroscopy of jet correlations can directly probe the index of refraction of this matter, which in turn will provide information about the mass scale of these partonic bound states.

Journal Article↗
PubMed2006

Phantom capnograph.

Explore the source record for details and available documents.

Anesthesia, Closed-Circuit↗
PubMed2005

Baryon-strangeness correlations: a diagnostic of strongly interacting matter.

The correlation between baryon number and strangeness elucidates the nature of strongly interacting matter, such as that formed transiently in high-energy nuclear collisions. This diagnostic can be extracted theoretically from lattice QCD calculations and experimentally from event-by-event fluctuations. The analysis of present lattice results above the critical temperature severely limits the presence of qq bound states, thus supporting a picture of independent (quasi)quarks.

Journal Article↗
PubMed2004

Fenofibrate-induced myopathy.

Fenofibrate induced myopathy is a rare adverse event. We present a case of muscle pain and quadriparesis following administration of 200mg of fenofibrate for 35 days. Patient gradually improved after stopping the drug. As per our knowledge, this is probably the first case report of fenofibrate induced myopathy from India.

Fenofibrate↗
PubMed2001

Effect of osmolytes and chaperone-like action of P-protein on folding of nucleocapsid protein of Chandipura virus.

Amino acid sequences of nucleocapsid proteins are mostly conserved among different rhabdoviruses. The protein plays a common functional role in different RNA viruses by enwrapping the viral genomic RNA in an RNase-resistant form. Upon expression of the nucleocapsid protein alone in COS cells and in bacteria, it forms large insoluble aggregates. In this work, we have reported for the first time the full-length cloning of the N gene of Chandipura virus and its expression in Escherichia coli in a soluble monomeric form and purification using nonionic detergents. The biological activity of the soluble recombinant protein has been tested, and it was found to possess efficient RNA-binding ability. The state of aggregation of the recombinant protein was monitored using light scattering. In the absence of nonionic detergents, it formed large aggregates. Aggregation was significantly reduced in the presence of osmolytes such as d-sorbitol. Aggregate formation was suppressed in the presence of another viral product, phosphoprotein P, in a chaperone-like manner. Both the osmolyte and phosphoprotein P also suppressed aggregation to a great extent during refolding from a guanidine hydrochloride-denatured form. The function of the phosphoprotein and osmolyte appears to be synergistic to keep the N-protein in a soluble biologically competent form in virus-infected cells.

Light↗
PubMed2001

LeuO expression in response to starvation for branched-chain amino acids.

The recently identified role of LeuO in the regulation of transcription has prompted us to search for the specific function(s) of LeuO in bacterial physiology. The cryptic nature of expression of leuO has previously limited such analysis. A conditional leuO expression was found when bacteria enter stationary phase and was shown to be guanosine 3',5'-bispyrophosphate-dependent. Multiple physiological events, including the stringent response, are induced upon the increase of the bacterial stress signal, guanosine 3',5'-bispyrophosphate. In this study, we tested whether LeuO was directly involved in the bacterial stringent response. LeuO was shown to be indispensable for growth resumption following a 2-h growth arrest caused by starvation for branched-chain amino acids in an E. coli K-12 relA1 strain. This result supports a functional role for LeuO in the bacterial stringent response.

Amino Acids, Branched-Chain↗
PubMed2000

A 72-base pair AT-rich DNA sequence element functions as a bacterial gene silencer.

We have previously demonstrated that sequential activation of the bacterial ilvIH-leuO-leuABCD gene cluster involves a promoter-relay mechanism. In the current study, we show that the final activation of the leuABCD operon is through a transcriptional derepression mechanism. The leuABCD operon is transcriptionally repressed by the presence of a 318-base pair AT-rich upstream element. LeuO is required for derepressing the repressed leuABCD operon. Deletion analysis of the repressive effect of the 318-bp element has led to the identification of a 72-bp AT-rich (78% A+T) DNA sequence element, AT4, which is capable of silencing a number of unrelated promoters in addition to the leuABCD promoter. AT4-mediated gene silencing is orientation-independent and occurs within a distance of 300 base pairs. Furthermore, an increased gene-silencing effect was observed with a tandemly repeated AT4 dimer. The possible mechanism of AT4-mediated gene silencing in bacteria is discussed.

Base Pairing↗
PubMed2000

ppGpp-dependent leuO expression in bacteria under stress.

Despite the known potential transcription regulatory role of leuO gene product, LeuO, the condition when leuO expresses during bacterial growth cycle remains unclear. Mechanistically, leuO expression was shown to be part of promoter relay mechanism, however, the factor(s) responsible for the regulation of leuO expression is not known. Combining Northern and Western results, we demonstrate in the present communication that leuO expression is normally low and enhanced when bacteria are in transition from exponential growth to stationary phase. The stationary phase-associated leuO expression is ppGpp dependent and rpoS (sigma(s) factor) independent.

Bacterial Proteins↗
PubMed1996

Anomalies in hepatobiliary excretion of technetium-99m-MAG3 preparations.

Technetium-99m-MAG3 is accepted as a renal tubular function agent. However, sporadic liver and gall bladder visualisation during its clinical use is clearly a disadvantage. HPLC-purified 99mTc-MAG3 samples exhibited appreciable hepatobiliary uptake (7%), and an elevated level of such uptake was observed in unpurified kit preparations, which was stated to be associated with the excretory property of the radiolabeled kit impurities. To verify this we attempted to quantitate the hepatobiliary uptake of the kit preparations with that of its radiolabeled components. The contribution of each component toward hepatobiliary uptake of the sample was calculated from their abundance in the chelate mixture and the individual biodistribution of the isolated components. However, the anticipated hepatobiliary uptake of different preparations of 99mTc-MAG3 calculated in this way was always lower than that of the experimental value determined directly. Further work is needed to explain the anomaly.

Animals↗
PubMed1991

Molecular and morphologic changes during the epithelial-mesenchymal transformation of palatal shelf medial edge epithelium in vitro.

The fate of the medial edge epithelial (MEE) cells during palatal fusion has been proposed to be either programmed cell death or epithelial-mesenchymal transformation. Vital cell labeling techniques were used to mark the MEE and observe their fate during palatal fusion in vitro. Fetal mouse palatal shelves were labeled with Dil and allowed to proceed through fusion while maintained in an organ culture system. The tissues were examined at several stages of palatal fusion for the distribution of Dil, presence of specific antigens and ultrastructural appearance of the cells. The MEE labeled with Dil occupied a midline position at all stages of palatal fusion. Initially the cells had keratin intermediate filaments and were separated from the underlying mesenchyme by an intact basement membrane. During the process of fusion the basement membrane was degraded and the Dil-labeled MEE were in contact with the mesenchymal-derived extracellular matrix. In the late stages of fusion the Dil-labeled MEE altered their cellular morphology, had vimentin intermediate filaments, and were not associated with an identifiable basement membrane. Dil-labeled cells, without an epithelial phenotype, remained present in the midline of the completely fused palate. The data indicate that the MEE did not die but underwent a phenotypic transformation to viable mesenchymal cell types, which were retained in the palatal mesenchyme.

Animals↗