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Biomedical subjects

P Chaudhari

Publications and source records attributed to P Chaudhari.

At least 19 recordsLinked to original sources
PubMed2005

Ribotyping of Indian isolates of Pasteurella multocida based on 16S and 23S rRNA genes.

The applicability of ribotyping based on 16S and 23S rRNA was evaluated for molecular epidemiological studies. Forty-eight isolates of Pasteurella multocida isolated from different hosts and geographical locations and one reference isolate were ribotyped. Only four ribotypes were found. All the isolates including reference isolate from wild carnivores had the same ribotype, though they had different serotypes. The isolate from a tiger had one band in addition to the bands present in the major ribotype. The isolates from lions represented two ribotypes; of these ribotypes, one (r2) had an additional band of 3.6 kbp, which was absent in all other ribotypes. The second ribotype (r4) from a lion had one band missing (6 kbp) that was present in the other ribotypes. These isolates were further typed using ERIC-PCR and REP-PCR. With ERIC-PCR and REP-PCR, higher D values of 0.83 and 0.89 were obtained. The current study revealed that ribotyping is not a very efficient typing tool for use in molecular epidemiology for differentiation of isolates.

Genes, Bacterial↗
PubMed2001

Liquid crystal alignment on carbonaceous surfaces with orientational order.

We used near-edge x-ray absorption fine structure (NEXAFS) spectroscopy to link the orientational bond order at three carbonaceous surfaces-rubbed polyimide, ion beam-irradiated polyimide, and ion beam-irradiated diamondlike carbon films-with the direction of liquid crystal (LC) alignment on these surfaces. We show that, in general, LC alignment can be created on any carbonaceous substrate by inducing orientational order at its surface. Our results form the scientific basis for LC alignment layers consisting of amorphous carbon films in which orientational order near the surface is induced by a directional low-energy ion beam.

Journal Article↗
PubMed2001

Atomic-beam alignment of inorganic materials for liquid-crystal displays.

The technique used to align liquid crystals-rubbing the surface of a substrate on which a liquid crystal is subsequently deposited-has been perfected by the multibillion-dollar liquid-crystal display industry. However, it is widely recognized that a non-contact alignment technique would be highly desirable for future generations of large, high-resolution liquid-crystal displays. A number of alternative alignment techniques have been reported, but none of these have so far been implemented in large-scale manufacturing. Here, we report a non-contact alignment process, which uses low-energy ion beams impinging at a glancing angle on amorphous inorganic films, such as diamond-like carbon. Using this approach, we have produced both laptop and desktop displays in pilot-line manufacturing, and found that displays of higher quality and reliability could be made at a lower cost than the rubbing technique. The mechanism of alignment is explained by adopting a random network model of atomic arrangement in the inorganic films. Order is induced by exposure to an ion beam because unfavourably oriented rings of atoms are selectively destroyed. The planes of the remaining rings are predominantly parallel to the direction of the ion beam.

Journal Article↗
PubMed1991

Cell-shape regulation and matrix protein p52 content in phenotypic variants of ras-transformed rat kidney fibroblasts. Functional analysis and biochemical comparison of p52 with proteins implicated in cell-shape determination.

The 52 kDa transformation-sensitive protein p52 was previously identified as a major substrate-associated component of normal rat kidney (NRK) fibroblasts [Higgins & Ryan (1989) Biochem. J. 257, 173-182]. p52 selectively localized to cellular fractions enriched in substrate focal-contact sites and associated ventral undersurface elements. Rapid attachment/spreading of NRK cells on to prepared p52 matrices and inhibition of fibroblast spreading by antibodies to p52 indicated that this protein participates in shape determination or cell-to-substrate adhesion. NRK cells transformed with Kirsten murine sarcoma virus (KiMSV), with a temperature-sensitive mutant (ts-371 KiMSV) and maintained at the permissive temperature, or with the cloned EJrasval.12 oncogene, exhibited down-regulated accumulation of p52 in the ventral undersurface region. Immunochemical, lectin-affinity and electrophoretic analyses indicated that p52 shares considerable sequence similarity with plasminogen-activator inhibitor type-1, which is consistent with its subcellular localization and likely morphoregulatory activity. The marked down-regulation of p52 expression seen in four different ras-mediated transformation systems, its induction prior to butyrate-induced morphological reorganization in KiMSV-transformed cells, and the morphological consequences of exogenously added p52 or p52 antibodies on NRK fibroblasts suggest that this protein probably functions in cell-shape regulation. Abrogation of p52 matrix accumulation typically seen in ras transformants may contribute, therefore, to the aberrant cytoarchitecture characteristic of malignant fibroblasts.

Animals↗
PubMed1990

p52 induction by cytochalasin D in rat kidney fibroblasts: homologies between p52 and plasminogen activator inhibitor type-1.

Normal rat kidney (NRK) fibroblasts respond to the cell shape-modulating chemical agent cytochalasin D (CD) with augmented synthesis of the 52-kDa substrate-associated protein p52. p52 is a complex glycoprotein, existing as 12 different isoforms, which include a 43-kDa "core" protein (p43), four 50-kDa species (p50-0,1,2,3), and at least seven distinct pI variants of the mature 52-kDa protein. A threshold of 2-4 microM CD was found to be necessary to augment p52 deposition into both the secreted protein- and saponin-resistant cytomatrix (SAP) fractions of NRK cells. This concentration of CD was also necessary to initiate significant cell rounding. Augmented p52 production in CD-treated NRK (NRK/CD) cells provided a means to assess the identity of this protein. p52 was found to be identical to rat plasminogen activator inhibitor type-1 (rPAI-1) and to PAI-1-like proteins of other species by comparative immunoprecipitation, 2-D electrophoretic profile, V8 protease digest mapping, and subcellular fractionation criteria. Quantitation of rPAI-1 cytoplasmic mRNA abundance, using the rPAI-1 cDNA probe pSS1-3, revealed an induction of rPAI-1 mRNA in NRK/CD cells which paralleled the increased protein production. CD-augmented p52(rPAI-1) synthesis and SAP deposition was blocked by actinomycin D, implicating a need for RNA synthesis during the period of CD exposure to effect induction. Augmentation of p52 expression in NRK/CD fibroblasts, thus, appears to involve both cell shape-associated metabolic processes and concomitant RNA synthesis.

Animals↗