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Biomedical subjects

V Ranjan

Publications and source records attributed to V Ranjan.

9 recordsLinked to original sources
PubMed2003

Strained hexagonal ScN: a material with unusual structural and optical properties.

Local-density approximation calculations are performed to predict properties of compressively strained hexagonal ScN. This material is found to exhibit a large electromechanical response, a structural phase transition from a nonpolar to a polar structure, and a variation of the band gap in the entire visible light range when continuously changing the compressive strain. Microscopic effects responsible for these anomalies are revealed and discussed. Suggestions on how to practically grow ScN-based materials having such unusual properties are also provided.

Journal Article↗
PubMed1997

Shear stress induction of the endothelial nitric oxide synthase gene is calcium-dependent but not calcium-activated.

Arterial levels of shear stress (25 dynes/cm2) can elevate constitutive endothelial nitric oxide synthase (eNOS) gene expression in cultured endothelial cells (Ranjan et al., 1995). By PhosphorImaging of Northern blots, we report that the eNOS/glyceraldehyde 3-phosphate dehydrogenase (GAPDH) messenger RNA (mRNA) ratio in bovine aortic endothelial cells (BAEC) increased by 4.8- and 7.95-fold after 6-hr shear stress exposure of 4 and 25 dynes/cm2, respectively. Incubation of BAEC with dexamethasone (1 microM) had no effect on shear stress induction of eNOS mRNA. Buffering of intracellular calcium in BAEC with bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)-ester (BAPTA/AM) reduced shear stress induction of eNOS mRNA by 70%. Yet, stimulation of BAEC with ionomycin (0.1-1.0 microM) for 6-24 hr to elevate intracellular calcium had no effect on eNOS mRNA. These studies indicated that the shear stress induction of eNOS mRNA was a calcium-dependent, but not calcium-activated, process. Shear stress was a very potent and rapid inducer of the eNOS mRNA, which could not be mimicked with phorbol myristrate acetate or endotoxin. Inhibition of tyrosine kinases with genistein (10 microM) or tyrphostin B46 (10 microM) or inhibition of G-protein signaling with guanosine 5'-O-(2-thiodiphosphate) (GDP-betaS) (600 microM, 6-hr preincubation) did not block the shear stress elevation of eNOS mRNA.

Animals↗
PubMed1995

Turner's syndrome with sex chromosome mosaicism.

The increased risk of gonadal neoplasia in cases of Turner's syndrome with sex chromosome mosaicism and the presence of Y chromosome material emphasises the need for a diligent search and removal of the streak gonads. One such case is reported here.

Adult↗
PubMed1995

Constitutive NOS expression in cultured endothelial cells is elevated by fluid shear stress.

The role of chronic fluid shear stress on endothelial constitutive nitric oxide synthase (cNOS) levels may have an important role in vessel diameter control. We subjected primary human umbilical vein endothelial cells (HUVEC) or bovine aortic endothelial cells (BAEC, passages 2-14) to steady laminar shear stress. In both cell types, the intracellular level of cNOS was elevated within 3 h of flow exposure at 25 dyn/cm2 and remained elevated at 6 and 12 h of flow exposure, compared with stationary controls, as indicated by digital immunofluorescence microscopy. Shear stress exposure for 6 h caused a 2.2 +/- 0.3- and 2.8 +/- 0.3-fold elevation of cNOS protein levels in BAEC (n = 3, P < 0.01) and HUVEC (n = 3, P < 0.01), respectively, in the presence or absence of 1 microM dexamethasone. Dexamethasone suppresses induction of the inducible NOS gene, indicating that cNOS was elevated by fluid shear stress. Flow exposure at 4 dyn/cm2 caused no enhancement of cNOS levels in either cell type. The flow induction of the cNOS protein levels was not blocked by preincubation of BAEC with 100-400 microM of NG-nitro-L-arginine methyl ester, indicating that flow-induced NO (or guanosine 3',5'-cyclic monophosphate) was not involved in the elevation of cNOS levels. Protein kinase C inhibitor H-7 (10 microM) had no effect on induction of NOS protein in BAEC exposed to 25 dyn/cm2. The cNOS mRNA levels were found to be elevated by two- to threefold in BAEC after 6 or 12 h of flow exposure at either 4 or 25 dyn/cm2, and this induction of NOS mRNA occurred in the presence of dexamethasone. The elevation of cNOS levels by chronic flow exposure may provide a mechanism for chronic regulation of vessel diameter by endothelial response to prevailing blood flow.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

Fluid shear stress induces synthesis and nuclear localization of c-fos in cultured human endothelial cells.

Quiescent cultured primary human umbilical vein endothelial cells were exposed to low levels (4 dynes/cm2) or arterial levels (25 dynes/cm2) of steady laminar shear stress for one hour. Intracellular c-fos protein was measured by immunocytochemistry and quantitative fluorescence video microscopy. The nuclear-localized c-fos protein level was 5.4 +/- 2.0 fold higher (p < 0.01) in the cells exposed to arterial levels of shear stress as compared to the cells maintained in stationary culture. In contrast, the cells exposed to low levels of shear stress showed diffuse but slightly elevated levels of c-fos (2.4 +/- 0.73 times higher than control; p < 0.01) without preferential nuclear localization. The protein kinase C inhibitor, H7 (10 microM) significantly attenuated the induction of c-fos by 50% in cells exposed to arterial shear stress for 1 hour.

Cell Compartmentation↗
PubMed1982

Evaluation of sulprostone for second trimester abortions and its effects on liver and kidney function.

Sulprostone was given intramuscularly in two dose schedules of 0.5 mg at 4 hourly intervals for 8 doses and 1.0 mg at 8-hour intervals for 4 doses to 56 women in the 12th-20th week of gestation coming for termination of pregnancy. Forty-nine of them aborted within the 30-hour observation period, giving a success rate of 87.5%. Within the observation period, the induction-abortion interval with the 0.5-mg schedule was 16.6 hours while the interval with the 1.0-mg schedule was 15.4 hours. Side effects caused by the drug were minimal and it was observed that patients receiving 1.0 mg Sulprostone had slightly more side effects per person than in those cases receiving 0.5 mg Sulprostone. Serum parameters assessing liver and kidney functions were carried out in 48 patients prior to, 24 hours later and two weeks after the abortion. There were significant changes in the levels of uric acid, potassium, serum proteins and SGOT, though these changes were within the normal range.

Abortifacient Agents↗
PubMedDate not supplied

Polymerase chain reaction vs. conventional diagnosis in fine needle aspirates of tuberculous lymph nodes.

OBJECTIVE: To compare four conventional methods of diagnosing tuberculous lymphadenophathy (TL)--namely fine needle aspiration cytology (FNAC), Zeihl-Neelsen staining of smears for acid-fast bacilli (AFB), culture for Mycobacterium tuberculosis (MTB) and lymph node biopsies--with the polymerase chain reaction (PCR) in order to assess the practicability and advantage of its use in routine diagnosis in a developing country. STUDY DESIGN: Fine needle aspirates from 142 consecutive patients presenting with lymphadenopathy (mainly cervical) without any known systemic involvement underwent cytomorphologic diagnosis, AFB smears, culture for MTB, confirmatory biopsy and PCR for MTB. The aspirates from cases other than TL served as controls for PCR. RESULTS: Correct diagnosis of tuberculosis could be made in 94.87% of cases by a combination of the four methods. PCR was done in 52 cases, 39 confirmed TL and 13 controls. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value of PCR were 94.44%, 38.23%, 44.73% and 92.85%, respectively, when culture alone was considered the gold standard. However, specificity (38.23-92.30%) and PPV (44.73-97.36%) of PCR increased remarkably when response to treatment was taken as the final arbiter. CONCLUSION: The four conventional tests were found to be the methods of choice for the diagnosis of TL in developing countries. PCR should be reserved for problem cases.

Biopsy, Needle↗