PubMed Health⌕ Search

Biomedical subjects

I Dasgupta

Publications and source records attributed to I Dasgupta.

At least 19 recordsLinked to original sources
PubMed2002

Molecular analysis of two complete rice tungro bacilliform virus genomic sequences from India.

The complete genomic sequences of two geographically distinct isolates of rice tungro bacilliform virus (RTBV) from India were determined. Both the sequences showed equal divergence from previously reported Southeast Asian isolates. Numerous insertions, deletions and substitutions, mostly in the intergenic regions, were found. The genome sizes were 7907 and 7934 bp respectively, 95 and 68 residues short of an infectious clone reported earlier. Between them, both the isolates showed high homology all along the genome, except for a 30-nucleotide insertion/deletion close to the 3' end of ORF III in one of them. Both the isolates indicated an unconventional start codon in ORF I, similar to the type isolate. In addition, as novel features, both the Indian isolates showed an unconventional start codon for ORF IV. Considering the low amounts of genome variability noticed in other RTBV isolates, the Indian isolates show that they have diverged sufficiently from the rest and should be considered belonging to a distinct strain.

Amino Acid Sequence↗
PubMed2001

Band-structure trend in hole-doped cuprates and correlation with T(c max).

By calculation and analysis of the bare conduction bands in a large number of hole-doped high-temperature superconductors, we have identified the range of the intralayer hopping as the essential, material-dependent parameter. It is controlled by the energy of the axial orbital, a hybrid between Cu 4s, apical-oxygen 2p(z), and farther orbitals. Materials with higher T(c max) have larger hopping ranges and axial orbitals more localized in the CuO2 layers.

Journal Article↗
PubMed1999

Management of hypertension in patients developing end-stage renal failure.

The benefits of treating hypertension include preventing or delaying the progression of chronic renal failure, and reducing the cardiovascular complications of patients with renal disease. We examined how well hypertension had been managed in all 145 patients from a single health district who started dialysis during a 3-year period. Data relating to management of hypertension, including all blood pressure readings, were obtained from their general practice and hospital case notes. The anonymized data were reviewed by two independent assessors against a set of standards based on the British Hypertension Society guidelines. There was close agreement between the assessors. Complete records were obtained in 98.5% of cases. Of the 145 patients, 107 (76.4%) were hypertensive before developing end-stage renal failure. There were departures from standards in all categories of care: 24.3% in detection/diagnosis, 29% in investigation, 22.4% in referring to a nephrologist, and 17% in follow-up. The British Hypertension Society recommended standard for diastolic blood pressure of 90 mmHg was achieved in only 45%. In 32%, the assessors independently concluded that poor blood pressure control might have affected adversely the progression of renal failure. New methods of dealing with these problems are required and possible approaches are discussed.

Adult↗
PubMed1996

Detection of rice tungro bacilliform virus in field and glasshouse samples from India using the polymerase chain reaction.

Rice tungro bacilliform virus (RTBV) together with rice tungro spherical virus (RTSV) is the causal agent for the rice tungro disease. A rapid technique was developed to detect RTBV DNA in the crude extract of freshly collected leaf samples by polymerase chain reaction (PCR). This technique can detect the viral DNA in 1000-fold diluted leaf extract. Detection has been possible in samples stored upto 5 days after the collection. This technique may have wide application for the field diagnosis of RTBV infection.

Badnavirus↗
PubMed1996

Variation in the genome of rice tungro bacilliform virus: molecular characterization of six isolates.

The DNA genomes of isolates of rice tungro bacilliform virus from Bangladesh, India, Indonesia, Malaysia and Thailand were cloned and compared with that of the type isolate from the Philippines. Restriction endonuclease maps revealed differences between the isolates and cross-hybridization showed that they fell into two groups, those from the Indian subcontinent and those from south-east Asian countries. The genomes of isolates from the Indian subcontinent contained a deletion of 64 bp when compared with those from south-east Asia. The implications of this variation are discussed.

Base Sequence↗
PubMed1994

Splicing in a plant pararetrovirus.

Analysis of expression in rice cells of plasmids in which an ATG-less chloramphenicol acetyl transferase ORF was placed in frame with the coding sequence of the pararetrovirus rice tungro bacilliform virus (RTBV) ORF IV, and which contained much of the upstream full-length transcript sequence of RTBV, gave evidence to suggest that a splicing event occurred. Reverse transcription/PCR of RNA from transfected protoplasts and from RTBV-infected plants yielded a product which confirmed that the 5' end of ORF IV was spliced in frame to a short ORF (sORF) in the RTBV leader sequence removing an intron of about 6.3 kb. Most of the translation is initiated at the ATG codon in the sORF with only about 10% at the ORF IV ATG codon. The efficiency of splicing appears to be inversely related to the length of the intron. The finding of splicing in a pararetrovirus blurs the differences between them and retroviruses but is in accord with the hypothesis that retroelements acquire genes and sequences which adapt them to specific niches.

Base Sequence↗
PubMed1991

An analysis of the sequence of an infectious clone of rice tungro bacilliform virus, a plant pararetrovirus.

The nucleotide sequence of an infectious clone of rice tungro bacilliform virus (RTBV) DNA has been determined. The circular genome has 8002 bp and one strand contains four open reading frames (ORFs). One ORF is potentially capable of encoding a protein of 24 kD (P24) and has no initiation (ATG) codon. The other three ORFs potentially encode proteins of 12 kD, 194 kD and 46 kD (P12, P194, P46) respectively. The functions of P24, P12 and P46 are unknown. Comparative analyses with retroviruses and Commelina yellow mottle virus suggest that the 194 kD putative product is a polyprotein that is proteolytically cleaved to yield the virion coat protein, a protease and replicase (reverse transcriptase and RNase H) characteristic of retroelements. The DNA sequence reveals other features which strongly support our belief that RTBV is a pararetrovirus. These include sequences at the mapped positions of two discontinuities in the virion DNA which are complementary to tRNA metinit and purine-rich, and may be the priming sites for minus- and plus-strand DNA synthesis respectively. As the positions of likely transcriptional signals suggest, a full-length viral transcript is observed by northern analysis. The predicted folding of the 645 bp 5'-region of this RNA resembles that of caulimoviruses. Comparisons with other reverse transcribing elements are discussed.

Amino Acid Sequence↗
PubMed1991

Rice tungro disease is caused by an RNA and a DNA virus.

We present evidence that rice tungro spherical virus (RTSV) has a genome of polyadenylated single-stranded RNA of about 10 kb whereas rice tungro bacilliform virus (RTBV) contains double-stranded circular DNA. RTBV DNA has been mapped and shown to have two discontinuities, one in each strand, at specific sites; it thus resembles that of the caulimoviruses. Gel electrophoresis of RTSV preparations revealed two protein bands (Mr 35K and 26K). RTBV yielded two major protein bands of 37K and 33K together with several minor species of higher and lower Mr which react with antiviral serum.

Capsid↗
PubMed1991

Rice tungro bacilliform virus DNA independently infects rice after Agrobacterium-mediated transfer.

In nature, rice tungro disease is caused by an RNA and a DNA virus complex, but we have obtained an independently infectious clone of rice tungro bacilliform virus (RTBV) DNA. Infectivity could be demonstrated only when a more than unit-length copy was cloned in the Agrobacterium binary vector Bin 19 and agroinoculated into rice plants. Rice plants thus agroinfected with cloned RTBV DNA showed typical symptoms of tungro disease, presence of viral DNA and bacilliform particles, and could be used as a source of virus to infect healthy plants by the green leafhopper (Nephotettix virescens). The importance of this infectious clone in understanding the molecular biology of RTBV and the rice tungro disease is discussed.

DNA, Viral↗
PubMed1988

Growth in height, weight and skinfold thickness of Bengali boys of Calcutta, India.

This is the first comprehensive growth study of male children of Bengali parentage. The cross-sectional survey was undertaken in an urban high school situated in the north of the Metropolitan City of Calcutta during 1982 and 1983. The sample consisted of 815 healthy Bengali boys aged 7-16 years. In this paper, data on height, weight, and skinfold thicknesses are presented including patterns of change in these physical traits with increasing age. Mean values of height or weight of the boys--not representative for all school-going boys of Calcutta--are distinctly above the national standards given by the Indian Council of Medical Research. They are, however, shorter and lighter than the well-off boys of India but have a similar magnitude of subcutaneous fat on arm. Peak annual incremental growth in height and weight occurs in Bengali boys at 12-13 years and 14-15 years, respectively. This is about one year earlier than in the well-off Indian, British, or American boys.

Adolescent↗