Interactions of bacterial polysaccharides with cationic dyes: Physicochemical studies.

Capsular polysaccharides (SPS) are an integral component of gram-negative bacteria, and also have potential use as vaccine. In this paper, interactions of SPS isolated from Klebsiella strains K20 and K51 with cationic dyes pinacyanol chloride (PCYN) and acridine orange (AO) were studied by absorbance and fluorescence measurements. Both the polysaccharides having glucuronic acid as the potential anionic site induced strong metachromasy (blue shift ~100 nm) in the PCYN. The spectral changes were studied at different polymer/dye molar ratios (P/D = 0-40). A complete reversal of metachromasy was observed upon addition of co-solvents, suggesting the breakaway of dye molecules from the biopolymer matrix. Binding constant, changes in free energy, enthalpy and entropy of the dye polymer complex were also computed from the spectral data at different temperatures to reveal the nature of the interaction. Quenching of fluorescence of AO by the polymers and the incorporated mechanisms were also explored.

Rabies: control strategies for Himalayan states of the Indian subcontinent.

Rabies remains to be one of the most important direct zoonosis and is invariably fatal once the clinical symptoms appear. The disease can be prevented but still people continue to die of infection. India alone accounts to 81 per cent of the total deaths occurring due to rabies across the world. Dog is major reservoir of the infection, although other domestic and wild reservoirs also play an important role in the spread of the disease. A large population of stray dogs, availability of susceptible hosts, close proximity of animals and man and lack of effective control strategies might have led to endemic status of the disease in India. The effective control of rabies can be achieved through reduction of the stray dogs and stray livestock populations through implementation of animal birth control (ABC) programme and the proper induction of "herd immunity" by mass vaccination and awareness health programme. The increase in human population, changes in the environment, increased transportation, development of human habitations in new places and seasonal migration of the animals have resulted in the introduction of the infection to new territories and changes in the epidemiology of the disease in hills. Therefore, it is essential to design area specific control programmes so that the disease can be eliminated effectively.

Purification and partial characterization of PfHRP-II protein of Plasmodium falciparum.

The human malarial parasite Plasmodium falciparum secretes various intra-and extra-cellular proteins during its asexual life cycle in human RBC. Histidine rich protein-II (HRP-II) is one of the most prominent proteins, found to be secreted by P. falciparum throughout the asexual cycle with the peak during mature schizont stage of the parasite development in human IRBC. The high histidine content (35% of the total amino acids in protein) of this protein suggested the potential to bind divalent metal ions. We have demonstrated by metal chelate chromatography, an extraordinary capacity of HRP-II to bind nickel ions (Ni++) and employed this characteristic to purify the extra-cellular HRP-II protein secreted by P. falciparum from culture supernatant. The identity of the purified protein was verified by the relative molecular weight on SDS-PAGE, by reacting with polyclonal antibodies directed against it using Western blot technique.

Applicability of Demirjian's method of age assessment in children of Davangere.

The assessment of age is an important facet in providing information in demographic studies and is of clinical use to diagnose and plan the treatment. The objective of this study was to determine whether the standards of dental maturation given by Demirjian et al are applicable to Davangere children and to assess the relationship between the obtained dental age and skeletal age. The study group comprised of 151 healthy children of 6-15 years age. It was found that Davangere children were dentally more advanced. Demirjians method gave an over estimation of 1.20 +/- 1.02 years and 0.90 +/- 0.87 years in males and females respectively. The obtained dental age was found to be different from the skeletal age. It may be concluded that Demirjians method of dental maturation is not applicable to the children of Davangere.

Spectral studies on the interaction of iodine and anthracene sulfonate with bacterial phospholipids from different mutants of Salmonella minnesota.

Using spectrophotometric and spectrofluorometric techniques, the interaction of iodine and 2-anthracene sulfonate (ANS) with the phospholipids (PL) isolated from four genetically correlated Salmonella minnesota isolates viz., a smooth form (S), a deeply rough mutant (Rc) and two intermediate forms (Ra and Rb) were studied. Appearance of an isosbestic point and a new band in absorption spectra indicated charge-transfer (C-T) interaction of iodine with the PL through the formation of 1:1 complex. Stern-Volmer type fluorescence quenching of PL was observed with the addition of iodine to PL, while PL enhanced the fluorescence of anionic dye ANS. The values of the binding constants between iodine/PL and ANS/PL, measured by using suitable equations, showed a systematic gradation in the molecular properties of the PL in the membrane structure in smooth (S) and rough (Ra, Rb and Rc) mutants of Salmonella minnesota.