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S Tripathy

Publications and source records attributed to S Tripathy.

26 records · Page 2Linked to original sources
PubMed1998

DNA bound to polypyrrole films: high-resolution imaging, DNA binding kinetics and internal migration.

We have studied the time-dependent uptake of 35S radiolabeled DNA with electrochemically prepared polypyrrole films. The two distinct polypyrrole film surfaces, a rough (solution polymeric growth face, R) and a smooth surface (electrode face, S) were characterized by low-resolution AFM and high-resolution transmission electron microscopy (TEM). These studies showed the presence of steep contours and defects in the form of large and small surface holes and valleys on the rough surface of polypyrrole. The void dimensions ranged from the nanoscale to micron size. By contrast, the smooth surface was flatter and largely devoid of significant structural defects and exhibited closer packing of the polypyrrole chains over large areas. Both surfaces were comprised largely of chains whose average diameters were 1.0-1.2 +/- 0.3 nm. The surface characterization studies were complemented by time-dependent DNA uptake studies which showed a t1/2-dependent total uptake of 35S DNA at higher levels on the rough surface compared to the smooth surface. This is consistent with the apparent higher effective surface area of the rough surface compared to the smooth. Using a proportional counter the time-dependent ratio (R/S) of the 35S DNA detected from the rough surface of the polypyrrole disk to that detected from the smooth surface suggested that DNA was migrating into the disk interior from its uptake surface. The rough side defect dimensions measured by TEM were more than sufficient to allow for the penetration and migration of DNA into the disk interior. Both R/S ratios were extrapolated and found to intersect at an R/S value close to 1.0, suggesting a kinetic process leading ultimately towards a nearly uniform radiolabeled DNA distribution in the disk. These kinetic results were in agreement with the surface characterization studies and suggest a model in which sizeable internal pores exist throughout the electrochemically prepared polypyrrole, that could account for the DNA migration effect. This was confirmed by TEM of the interior of a polypyrrole disk produced by Argon ion milling.

Adsorption↗
PubMed1998

N-Acylethanolamines: formation and molecular composition of a new class of plant lipids

Recently, the biosynthesis of an unusual membrane phospholipid, N-acylphosphatidylethanolamine (NAPE), was found to increase in elicitor-treated tobacco (Nicotiana tabacum L.) cells (K.D. Chapman, A. Conyers-Hackson, R.A. Moreau, S. Tripathy [1995] Physiol Plant 95: 120-126). Here we report that before induction of NAPE biosynthesis, N-acylethanolamine (NAE) is released from NAPE in cultured tobacco cells 10 min after treatment with the fungal elicitor xylanase. In radiolabeling experiments [14C]NAE (labeled on the ethanolamine carbons) increased approximately 6-fold in the culture medium, whereas [14C]NAPE associated with cells decreased approximately 5-fold. Two predominant NAE molecular species, N-lauroylethanolamine and N-myristoylethanolamine, were specifically identified by gas chromatography-mass spectrometry in lipids extracted from culture medium, and both increased in concentration after elicitor treatment. NAEs were found to accumulate extracellularly only. A microsomal phospholipase D activity was discovered that formed NAE from NAPE; its activity in vitro was stimulated about 20-fold by mastoparan, suggesting that NAPE hydrolysis is highly regulated, perhaps by G-proteins. Furthermore, an NAE amidohydrolase activity that catalyzed the hydrolysis of NAE in vitro was detected in homogenates of tobacco cells. Collectively, these results characterize structurally a new class of plant lipids and identify the enzymatic machinery involved in its formation and inactivation in elicitor-treated tobacco cells. Recent evidence indicating a signaling role for NAPE metabolism in mammalian cells (H.H.O. Schmid, P.C. Schmid, V. Natarajan [1996] Chem Phys Lipids 80: 133-142) raises the possibility that a similar mechanism may operate in plant cells.

Journal Article↗
PubMed1996

HIV-1 pol sequences from India fit distinct subtype pattern.

HIV-1 isolates are classified phylogenetically in several subtypes or clades according to env and gag coding sequences. Viral subtypes tend to cluster geographically. DNA sequences encoding the p51 subunit of reverse transcriptase were obtained by nested polymerase chain reaction from peripheral blood mononuclear cells of two HIV-1-seropositive individuals from New Delhi and three from Pune, in northern and western India, respectively. These isolates were previously characterized as subtype C according to their env sequences. Based on phylogenetic analysis, the reverse transcriptase coding region of these isolates is distinct from those of subtype A, subtype B, subtype D, and group O of HIV-1 viruses. The nucleotide divergence of these Indian pol sequences (3.3%) is similar to that of existing sequences for subtype B and subtype D viruses. This result supports the epidemiologic data of a more recently introduced HIV-1 epidemic in India. Based on the corresponding env sequences, the pol sequences described in this report are subtype C.

Amino Acid Sequence↗
PubMed1990

Clinical profile, therapeutic approach and outcome of gouty arthritis in northern India.

Thirty patients with gouty arthritis were studied over 3 years. The diagnosis was established with the help of polarised light microscopy. All the patients were males, with a median age of 45 years. They belonged to the middle or upper socio-economic class and were obese (mean body mass index 29.7). Chronic alcoholism, diabetes mellitus and hypertension were present in one patient each. No patient had symptomatic coronary artery disease. Although 6 patients had a history of renal colic, only one had gouty nephropathy with chronic renal failure. Six patients had a positive family history of gout. The disease involved mostly the joints of the lower extremity and podagra was observed in 70% of patients. Eight patients had tophi at various sites. There were 17 'over producers' and 13 'under excretors' of uric acid. The treatment consisted of patient education, symptomatic control with non steroidal anti-inflammatory drugs and/or colchicine and antihyperuricaemic therapy. The overproducers were treated with allopurinol while the under excretors were treated with [corrected] sulfinpyrazone. In general, there was a good response to therapy as indicated by lowering of serum uric acid and the number of painful episodes per year. The overall profile of the disease appears similar to that seen in the West.

Adult↗
PubMedDate not supplied

Atomistic modeling of interphases in spider silk fibers.

We present a structural description of the intercrystalline polymer interphase based on atomistic modeling for spider dragline silk fibers. In the model small crystallites are connected by interphases. The interphases are assumed to be thin layers (< 4 nm) of statistically arranged chains. The calculated mechanical moduli of these interphases are significantly greater than the isotropic amorphous material.

Animals↗
PubMedDate not supplied

Increased promoter diversity reveals a complex phylogeny of human immunodeficiency virus type 1 subtype C in India.

OBJECTIVE: To evaluate human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) sequence diversity among distinct populations within India and to determine the prevalent subtype. STUDY DESIGN/METHODS: Analysis of the 3'LTR was conducted from 28 HIV-1-positive samples: 1992-1993 (Pune, New Delhi) and 1995-1996 (Pune, Mumbai and Vellore). Genomic DNA was extracted from cocultivated peripheral blood mononuclear cells (PBMCs) and used for polymerase chain reaction (PCR) amplification and sequencing using dye terminator chemistry. Sequences were edited, aligned, and analyzed phylogenetically utilizing gap-stripped and bootstrapping parameters. Mobility shift assays were used to confirm binding activity. RESULTS: All nucleotide sequences were HWV-1 subtype C based on phylogenetic analysis. The isolates from Pune/Delhi formed subclusters when analyzed separately, irrespective of time or sample source. However, no significant subclustering was observed with isolates from Mumbai or Vellore or with the entire sample set when analyzed collectively. Subtype-specific enhancer analysis revealed an expected third NF-kappaB site but also revealed six isolates with insertions and deletions not previously described, one of which resembles an AP-1 binding site. CONCLUSIONS: The results confirm the prevalence of HIV-1C and suggest increasingly complex phylogeny of HIV-1C within India, such that the previously observed subclustering may no longer adequately reflect the diversity of isolates currently circulating throughout India.

Base Sequence↗
PubMedDate not supplied

Fast track thrombolysis in acute myocardial infarction: a quality improvement project.

Thrombolytic therapy for acute myocardial infarction has been proved to be most effective if given very early in the course of evolving infarction. This study was undertaken to optimise such treatment by overcoming the in-hospital delay in the existing set-up of an industrial hospital. A quality improvement project was undertaken to analyse the existing system of thrombolysing 46 consecutive patients of acute myocardial infarction treated in six months. By following the breakthrough sequence and proceeding in steps, the causes for delay in door to needle time were identified and rectified over two months. Impact of such measures in 32 patients of acute myocardial infarction thrombolysed consecutively in the next five months was studied. Door to needle time in the baseline group (n = 46) was in the range of 15-145 minutes and the average was 48.9 minutes. Only 32.6 percent of the patients in this group were thrombolysed within 30 minutes of arrival in the hospital. After the corrective measures were implemented in a study group of 32 patients, 27 with clear indication on admission were thrombolysed on the fast track i.e. with minimum delay. Five patients with doubtful need were put on the slow track and subsequently thrombolysed. Patients with no indication or a contra-indication for thrombolysis were excluded from this study. In the fast group, door to needle time reduced to an average of 22.56 minutes with a range of 7 to 67 minutes and 75 percent of the thrombolysed patients received the infusion within 30 minutes of arrival in the hospital. Differences in door to needle time between the two groups were statistically significant. Streamlining the hospital systems and procedures can help reduce the door to needle time in thrombolysing patients of acute myocardial infarction. This could be achieved within the existing resources by applying the principles of total quality improvement.

Coronary Care Units↗