Search Results

You are looking at 1 - 6 of 6 items

  • Author: S. Adhikari x
Clear All Modify Search

Abstract

Temperature dependent spectra of an oxazine laser dye, cresyl fast violet, has been studied within a concentration range of 5.0 × 10−5 M to 8.0 × 10−4 M. The temperature induced shifting of monomer–dimer equilibrium is accompanied by partial unfolding of dimer geometry in solution. While the modified π–π interaction due to temperature variation affects both monomer and the dimer spectra, changes in the geometrical disposition of the dimer are manifested in the exciton splitting of the dimer spectra.

ABSTRACT

Damping effects are of great interest for structural analysis and evaluations. Structural modal damping characteristics can be obtained from experiments. This paper introduces new possibilities for the modelling of the damping of a dynamic system with classical normal modes and provides an overview of the known methods for formulating a damping matrix base with experimental modal damping values. The proposed method offers an opportunity to extrapolate modal damping values for unmeasured modes by a regression method based on the measured modal properties. The points of view on the choice of an analytical form for damping regression functions are examined. An analytical form of regression functions can be chosen as the modal decay rate versus the square of the frequency or the modal damping ratio versus the frequency. Damping regressions can be performed based on a group of typical vibration modes, such as bending, torsion and lateral, symmetrical or anti-symmetrical modes. The regression data obtained for the damping constants can then be applied in a finite element model for further structural analysis.

The acetylation of proteins in biological systems is largely catalyzed by specific acetyl transferases utilizing acetyl CoA as the acetyl donor. The enzymatic acetylation of proteins independent of acetyl CoA was unknown until we discovered a unique membrane-bound enzyme in mammalian cells catalyzing the transfer of acetyl groups from polyphenolic peracetates (PAs) to certain enzyme proteins, resulting in the modulation of their catalytic activities. Since for the enzyme, acetyl derivatives of several classes of polyphenols such as coumarins, flavones, chromones, and xanthones were found to be acetyl donors, the enzyme was termed as acetoxy drug: protein transacetylase (TAase). TAase was found to be ubiquitously present in tissues of several animal species and a variety of animal cells. Liver microsomal cytochrome P-450 (CYP), NADPH-cytochrome c reductase and cytosolic glutathione S-transferase (GST) were found to be the targets for TAase-catalyzed acetylation by the model acetoxy drug 7,8-diacetoxy-4-methylcoumarin (DAMC). Accordingly, the catalytic activities of CYP-linked, mixed function oxidases (MFOs) and GST were irreversibly inhibited while the reductase was remarkably activated. In this report, we have reviewed the details concerning purification and characterization of TAase and the protein acetylation by DAMC. Quantitative structure–activity relationship (QSAR) studies concerning the specificities of various PAs to liver microsomal TAase and TAase-related biological effects have also been reviewed.

Abstract

Two new limonoids, kostchyienones A (1) and B (2), along with 12 known compounds 3–14 were isolated from the roots of Pseudocedrela kostchyi. Compound (7) was isolated for the first time from a natural source. Their structures were elucidated on the basis of spectroscopic evidence. Compounds 1–6 and 13–14 gave IC50 values ranging from 0.75 to 5.62 μg/mL for antiplasmodial activity against chloroquine-sensitive (Pf3D7) and chloroquine-resistant (PfINDO) strains of Plasmodium falciparum. Compound 5 showed moderate potential cytotoxicity against the HEK239T cell line with an IC50 value of 22.2±0.89 μg/mL. The antiplasmodial efficacy of the isolated compounds supports the medicinal value of this plant and its potential to provide novel antimalarial drugs.

Abstract

Background

Pregnancy is associated with biochemical changes leading to increased nutritional demands for the developing fetus that result in altered micronutrient status. The Indian dietary pattern is highly diversified and the data about dietary intake patterns, blood micronutrient profiles and their relation to low birthweight (LBW) is scarce.

Methods

Healthy pregnant women (HPW) were enrolled and followed-up to their assess dietary intake of nutrients, micronutrient profiles and birthweight using a dietary recall method, serum analysis and infant weight measurements, respectively.

Results

At enrolment, more than 90% of HPW had a dietary intake below the recommended dietary allowance (RDA). A significant change in the dietary intake pattern of energy, protein, fat, vitamin A and vitamin C (P < 0.001) was seen except for iron (Fe) [chi-squared (χ2) = 3.16, P = 0.177]. Zinc (Zn) deficiency, magnesium deficiency (MgDef) and anemia ranged between 54–67%, 18–43% and 33–93% which was aggravated at each follow-up visit (P ≤ 0.05). MgDef was significantly associated with LBW [odds ratio (OR): 4.21; P = 0.01] and the risk exacerbate with the persistence of deficiency along with gestation (OR: 7.34; P = 0.04). Pre-delivery (OR: 0.57; P = 0.04) and postpartum (OR: 0.37; P = 0.05) anemia, and a vitamin A-deficient diet (OR: 3.78; P = 0.04) were significantly associated with LBW. LBW risk was much higher in women consuming a vitamin A-deficient diet throughout gestation compared to vitamin A-sufficient dietary intake (OR: 10.00; P = 0.05).

Conclusion

The studied population had a dietary intake well below the RDA. MgDef, anemia and a vitamin A-deficient diet were found to be associated with an increased likelihood of LBW. Nutrient enrichment strategies should be used to combat prevalent micronutrient deficiencies and LBW.