University of Hyderabad

About: University of Hyderabad is a education organization based out in Hyderabad, India. It is known for research contribution in the topics: Catalysis & Crystal structure. The organization has 6446 authors who have published 13005 publications receiving 237641 citations. The organization is also known as: Hyderabad Central University & HCU.

Development and validation of a real-time PCR for detection of pathogenic leptospira species in clinical materials.

Abstract: Available serological diagnostics do not allow the confirmation of clinically suspected leptospirosis at the early acute phase of illness. Several conventional and real-time PCRs for the early diagnosis of leptospirosis have been described but these have been incompletely evaluated. We developed a SYBR Green-based real-time PCR targeting secY and validated it according to international guidelines. To determine the analytical specificity, DNA from 56 Leptospira strains belonging to pathogenic, non-pathogenic and intermediate Leptospira spp. as well as 46 other micro-organisms was included in this study. All the pathogenic Leptospira gave a positive reaction. We found no cross-reaction with saprophytic Leptospira and other micro-organisms, implying a high analytical specificity. The analytical sensitivity of the PCR was one copy per reaction from cultured homologous strain M 20 and 1.2 and 1.5 copy for heterologous strains 1342 K and Sarmin, respectively. In spiked serum & blood and kidney tissue the sensitivity was 10 and 20 copies for M 20, 15 and 30 copies for 1342 K and 30 and 50 copies for Sarmin. To determine the diagnostic sensitivity (DSe) and specificity (DSp), clinical blood samples from 26 laboratory-confirmed and 107 negative patients suspected of leptospirosis were enrolled as a prospective consecutive cohort. Based on culture as the gold standard, we found a DSe and DSp of 100% and 93%, respectively. All eight PCR positive samples that had a negative culture seroconverted later on, implying a higher actual DSp. When using culture and serology as the gold standard, the DSe was lower (89%) while the DSp was higher (100%). DSe was 100% in samples collected within the first – for treatment important - 4 days after onset of the illness. Reproducibility and repeatability of the assay, determined by blind testing kidney samples from 20 confirmed positive and 20 negative rodents both appeared 100%. In conclusion we have described for the first time the development of a robust SYBR Green real-time PCR for the detection of pathogenic Leptospira combined with a detailed assessment of its clinical accuracy, thus providing a method for the early diagnosis of leptospirosis with a well-defined satisfactory performance.

Spontaneous emission of a cesium atom near a nanofiber: Efficient coupling of light to guided modes

Abstract: We study the spontaneous emission of a cesium atom in the vicinity of a subwavelength-diameter fiber. We show that the confinement of the guided modes and the degeneracy of the excited and ground states substantially affect the spontaneous emission process. We demonstrate that different magnetic sublevels have different decay rates. When the fiber radius is about $200\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, a significant fraction (up to 28%) of spontaneous emission by the atom can be channeled into guided modes. Our results may find applications for developing nanoprobes for atoms and efficient couplers for subwavelength-diameter fibers.

Cocrystals of 1,3,5-Cyclohexanetricarboxylic Acid with 4,4‘-Bipyridine Homologues: Acid···Pyridine Hydrogen Bonding in Neutral and Ionic Complexes

Abstract: cis,cis-1,3,5-Cyclohexanetricarboxylic acid (H3CTA) is crystallized with bipyridine bases 1,2-bis(4-pyridyl)ethane (bipy-eta), 1,4-bis(4-pyridyl-2-ethyl)benzene (bipy-etabz), 1,2-bis(4-pyridyl)ethylene (bipy-ete), and 1,4-bis(2-(4-pyridyl)ethenyl)benzene (bipy-etebz) to afford molecular complexes (H3CTA)·(bipy-eta)1.5 1, (H3CTA)·(bipy-etabz) 2, (H2CTA-)·(bipy-ete2H+)0.5 3, and (H2CTA-)·(bipy-etebz2H+)0.5 4. Cocrystal 1 has a super honeycomb hydrogen bond network stabilized by carboxylic acid-bipyridine O−H···N synthon Va. The hexagonal cavity of 34.1 × 36.7 A is filled by parallel triple interpenetration of independent networks. 2 has zigzag chains of synthon Va connected via O−H···O hydrogen bonds. Carboxylic acid to pyridine proton transfer occurs in 3 and 4. These structures have undulated and flat 2D layers of O−H···O- and O−H···O hydrogen bonds that are connected to bipyridinium via N+−H···O- hydrogen bond Vb. H2CTA- anions in 4 form a porous parquet grid of 14.5 × 7.5 A with the channels accommodati...