Formulation and Evaluation of Gastroretentive Dosage Forms of Clarithromycin

The purpose of this research was to develop the hydrodynamically balanced delivery system of Clarithromycin (CLA) which, after oral administration should have the ability to prolong gastric residence time with the desired in vitro release profile for the localized action in the stomach, in the treatment of Helicobacter pylori (H.pylori) mediated peptic ulcer. By applying wet granulation technique floating tablets of Clarithromycin were prepared. The proportion of sodium bicarbonate was varied to get the least possible lag time, also the polymer part varied to get the desired release. In vivo radiographic studies were performed with Barium sulphate loaded formulation to justify the increased gastric residence time of the dosage form in the stomach, based on the floating principle. The formulation developed using 66.2% Clarithromycin, 12% HPMC K4M polymer, 8% sodium bicarbonate gave floating lag time less than 3 min with a floating time of 12 h, and an in vitro release profile very near to the desired release. X-ray studies showed the enhanced gastric residence time of the tablet to 220 ± 30 min. The mechanism of release of Clarithromycin from the floating tablets is anomalous diffusion transport and follows zero order kinetics. In vivo radiographic studies suggest that the tablet has increased gastric residence time for the effective localized action of the antibiotic (Clarithromycin) in the treatment of H.pylori mediated peptic ulcer.     

Design and synthesis of 4-morpholino-6-(1,2,3,6-tetrahydropyridin-4-yl)-N-(3,4,5-trimethoxyphenyl)-1,3,5-triazin-2-amine analogues as tubulin polymerization inhibitors

A series of thirty-seven 1,3,5-triazine analogues have been synthesized, characterized and evaluated for their antiproliferative activity against a panel of four different human cancer cell lines such as HeLa, HepG2, A549 and MCF-7. Most of the 1,3,5-triazine analogues exhibited promising antiproliferative activity against tested cancer cell lines. Among all the synthesized compounds, 8j showed potent activity against the cancer cell lines such as HeLa, HepG2, A549 and MCF-7 with IC₅₀ 12.3 ± 0.8, 9.6 ± 0.4, 10.5 ± 1.0 and 11.7 ± 0.5 μM respectively. 8j was taken up for elaborate biological studies and the cells in the cell cycle were arrested in G2/M phase. In addition, 8j was examined for its effect on the microtubule system with a tubulin polymerization assay, immunofluorescence. 8j showed remarkable inhibition of tubulin polymerization. Molecular docking studies were also carried out to understand the binding pattern. The studies suggested that 8j has a good binding affinity of ?7.949 towards nocodazole binding site of tubulin while nocodazole has ?7.462.     

Conformational heterogeneity in the Hsp70 chaperone‐substrate ensemble identified from analysis of NMR‐detected titration data

The Hsp70 chaperone system plays a critical role in cellular homeostasis by binding to client protein molecules. We have recently shown by methyl‐TROSY NMR methods that the Escherichia coli Hsp70, DnaK, can form multiple bound complexes with a small client protein, hTRF1. In an effort to characterize the interactions further we report here the results of an NMR‐based titration study of hTRF1 and DnaK, where both molecular components are monitored simultaneously, leading to a binding model. A central finding is the formation of a previously undetected 3:1 hTRF1‐DnaK complex, suggesting that under heat shock conditions, DnaK might be able to protect cytosolic proteins whose net concentrations would exceed that of the chaperone. Moreover, these results provide new insight into the heterogeneous ensemble of complexes formed by DnaK chaperones and further emphasize the unique role of NMR spectroscopy in obtaining information about individual events in a complex binding scheme by exploiting a large number of probes that report uniquely on distinct binding processes.     

Transcriptional Activation of Glutamate Decarboxylase and F-Box DUF Protein-Encoding Genes Promote Enhanced Abiotic Stress Tolerance and Improved Agronomic Traits in Indica Rice

Journal of Plant Growth Regulation - In the present study, an activation-tagged (AT) rice line T8-Ds-RFP3 developed has been tested for its ability to combat drought and salinity stress conditions...     

Changes in proteins and peroxidases induced by compatible pollination in the ovary of Nicotiana tabacum L. ahead of the advancing pollen tubes

Proteins and peroxidases produced by the ovules and placenta of tobacco (Nicotiana tabacum L.) in response to compatible pollination were analyzed by two-dimensional polyacrylamide gel electrophoresis and by enzyme staining in flat-bed native isoelectric focusing gels. For two-dimensional gels, ovaries were sampled at 36 h after pollination, at which time pollen tubes have penetrated much of the length of the style but have not yet entered the ovary. At least 11 major proteins from pollinated ovaries had no detectable counterparts in unpollinated ovaries. These showed a range of molecular mass and pI. For peroxidase isozyme assays, ovaries were sampled at 0, 12, 24, 36 and 48 h after pollination. At 45–50 h, pollen tubes were beginning to enter the top of the ovary but could still be separated from the ovules and placenta during sampling. Ovules and placentae from unpollinated pistils showed only one form of peroxidase, whereas those from pollinated pistils showed additional isozymes at pH 5.4 and pH 10.0. Both new isozymes increased in staining intensity over the first 36 h after pollination. At 48 h, however, the acidic peroxidase had continued to increase, while the basic component had declined so as to be barely detectable. The observations are discussed in relation to accumulating evidence that some form of pollination-induced signal reaches the ovary ahead of the advancing pollen tubes. The nature of this signal and possible involvement of peroxidases are also briefly discussed.     

Determination of terazosin in human plasma, using high-performance liquid chromatography with fluorescence detection

A selective, sensitive, rapid and reproducible high-performance liquid chromatographic method for the determination of terazosin in plasma is described. The structurally related compound prazosin was used as an internal standard. The method comprises extraction with methylene chloride followed by chromatography on a C₁₈ reversed-phase column. The compounds were detected using spectrofluorimetry. The absolute recoveries were more than 90% with a minimal detection of 1 ng/ml and calibration curve was linear between 1 and 80 ng/ml.     

LEAF DEVELOPMENT IN THE NORMAL AND SOLANIFOLIA MUTANT OF TOMATO (LYCOPERSICON ESCULENTUM)

Leaf development in the normal (lobed margin) and the solanifolia (sf/sf) mutant (entire margin) of tomato (Lycopersicon esculentum) was compared at the light and scanning electron microscope levels. The shoot apices of the mutant plants contained microbodies near the axil of the youngest leaf, which were absent in the normal plants. The structural and morphological events in the initiation of leaf primordia were similar in the two genotypes. The pattern of leaflet emergence was also similar in the two types of plants, but the timing of leaflet production was different. The first pair of leaflet primordia in the normal plants was produced on P₃, whereas in the mutant it was not produced until P₅. The adult leaves of sf/sf plants were larger than those of normal, and the greater leaf area in the mutant was associated with a greater adaxial epidermal cell and areole area. A continuous marginal fimbriate vein (MFV) was present along the margin of each of the normal leaflets. However, a continuous MFV was absent in the mutant leaflets. It is suggested that the absence of a continuous MFV in the mutant might alter the nutritional and hormonal supply to the leaf margin, which ultimately leads to a modified leaf, i.e., with an entire margin.     

Role of α-galactosidase in cell wall metabolism of date palm (Phoenix dactylifera) endosperm

Summary The endosperm of developing date palm (Phoenix dactylifera) seeds was sampled at regular intervals from pollination to mature fruit. The galactose content of the cell wall mannans was assessed. Accumulation of -galactosidase, a cell wall hydrolase, during endosperm development was analyzed by isoelectric focusing, sodium dodecyl sulfate polyacrylamide gel electrophoresis in combination with Western blotting and immunolocalization on tissue sections. N-terminal amino acid sequence of the first 15 amino acids showed homology with amino acids 71 to 85 of the sequence reported for the mature guar protein. Four forms of the enzyme with isoelectric points ranging from 4.4 to 5.2 appeared by 11 weeks after pollination, and all forms remained until maturity. A major band of 41 kDa and several lower M_r, lightly staining bands cross reacted with the anti--galactosidase antiserum. The major band remained until maturity while the lightly staining bands gradually disappeared. In the mobilizing endosperm of germinated seeds, two darkly staining bands were observed at 41 and 40 kDa. At 9 weeks after pollination, the endosperm was cellular and the silver enhanced gold label localizing -galactosidase occurred predominantly in the cell periphery. By 11 weeks, the label was present in the cytoplasm, but lacking on the thickening cell wall. -Galactosidase accumulated in the protein bodies along with the storage protein. At 13 to 17 weeks, the label accumulated and then was lost in a centrifugal pattern (from the middle lamella inward) from the cell walls as they matured and was lost in the cytoplasm. The mature endosperm cells had intense label present only over the protein bodies and over the inner cell wall. These observations suggest that -galactosidase is synthesized during endosperm development and unique forms of the enzyme are associated with cell wall maturation and cell wall mobilization in this species.     

Role of ABA in stamen and pistil development in the normal and solanifolia mutant of tomato (Lycopersicon esculentum)

Summary The role of abscisic acid (ABA) in stamen and pistil development of the normal and solanifolia (sf/sf) mutant of tomato (Lycopersicon esculentum Mill.) was analyzed. The solanifolia mutant produces flowers with separate floral organs, unlike the fused organs of normal flowers, and has greater number of carpels and locules per ovary than the normal. Applications of 10^–5 M ABA to normal floral buds produced flowers with separate stamens, but higher concentrations (10^–4 M ABA) resulted in the complete suppression of stamen growth or stamens that were devoid of anthers. ABA at both 10^–4 and 10^–5 M also induced an increase in the number of carpels and locules in normal flowers, but not in mutant ones. Analysis of endogenous ABA by a radioimmunoassay revealed that the pistils of mutant flowers contained a significantly higher level of ABA than those of normal flowers, but there was no difference in the ABA content of the stamens. The non-fusion of the stamens and the high number of carpels and locules in solanifolia mutant flowers may be explained by the high level of ABA in the floral apex during the initiation and development of carpels.