Visceral and Subcutaneous Adiposity and Brachial Artery Vasodilator Function

Endothelial dysfunction may link obesity to cardiovascular disease (CVD). We tested the hypothesis that visceral abdominal tissue (VAT) as compared with subcutaneous adipose tissue (SAT) is more related to endothelium‐dependent vasodilation. Among Framingham Offspring and Third Generation cohorts (n = 3,020, mean age 50 years, 47% women), we used multivariable linear regression adjusted for CVD and its risk factors to relate computed tomography (CT)‐assessed VAT and SAT, BMI, and waist circumference (WC), with brachial artery measures. In multivariable‐adjusted models, BMI, WC, VAT, and SAT were positively related to baseline artery diameter and baseline mean flow velocity (all P < 0.001), but not hyperemic mean flow velocity. In multivariable‐adjusted models, BMI (P = 0.002), WC (P = 0.001), and VAT (P = 0.01), but not SAT (P = 0.24) were inversely associated with percentage of flow‐mediated dilation (FMD%). However, there was little incremental increase in the proportion of variability explained by VAT (R² = 0.266) as compared to SAT (R² = 0.265), above and beyond traditional risk factors. VAT, but not SAT was associated with FMD% after adjusting for clinical covariates. Nevertheless, the differential association with VAT as compared to SAT was minimal.     

Preparation and Characterization of Co-Grinded Mixtures of Aceclofenac and Neusilin US2 for Dissolution Enhancement of Aceclofenac

The present study was carried out with a view to enhance the dissolution of poorly water-soluble BCS-class II drug aceclofenac by co-grinding with novel porous carrier Neusilin US_2. (amorphous microporous granules of magnesium aluminosilicate, Fuji Chemical Industry, Toyama, Japan). Neusilin US₂ has been used as an important pharmaceutical excipient for solubility enhancement. Co-grinding of aceclofenac with Neusilin US₂ in a ratio of 1:5 was carried out by ball milling for 20 h. Samples of co-ground mixtures were withdrawn at the end of every 5 h. and characterized for X-ray powder diffraction, differential scanning calorimetry, and Fourier-transform infrared spectroscopy. The analysis revealed the conversion of crystalline aceclofenac to its amorphous form upon milling with Neusilin US₂. Further, in vitro dissolution rate of aceclofenac from co-ground mixture was significantly higher compared to pure aceclofenac. The accelerated stability study of co-ground mixture was carried out at 40°C/75%RH for 4 weeks, and it showed that there was no reversion from amorphous to crystalline form. Thus, it is advantageous to use a porous carrier like Neusilin US₂ in improvement of dissolution of poorly soluble drugs.     

Fabrication of Modified Release Tablet Formulation of Metoprolol Succinate using Hydroxypropyl Methylcellulose and Xanthan Gum

The present investigation was undertaken to fabricate modified release tablet of metoprolol succinate using hydroxypropyl methylcellulose (HPMC) and xanthan gum as a matrixing agent. A 3² full factorial design was employed for the optimization of formulation. The percentage drug released at a given time (Y ₆₀, Y ₂₄₀ and Y ₇₂₀) and the time required for a given percentage of drug to be released (t _50%) were selected as dependent variables. The in vitro drug dissolution study was carried out in pH 6.8 phosphate buffer employing paddle rotated at 50 rpm. The similarity factor (f ₂) was calculated for selection of best batch considering mean in vitro dissolution data of Seloken® XL as a reference profile. It is concluded that the desired drug release pattern can be obtained by using a proper combination of HPMC (high gelling ability) and xanthan gum (quick gelling tendency). The economy of xanthan gum and faster hydration rate favors its use in modified release tablets. The matrix integrity during dissolution testing was maintained by using hydroxypropyl methylcellulose.     

Poly(D,L-Lactide-Co-Glycolide) microspheres containing 5-fluorouracil: Optimization of process parameters

The objective of this research was to optimize the processing parameters for poly(D,L-lactide-coglycolide) (PLGA) microspheres of 5-fluorouracil (5-FU) and to mathematically relate the process parameters and properties of microspheres. Microspheres were prepared by a water-in-oil-in-water emulsion solvent evaporation technique. A 3² factorial design was employed to study the effect of the volume of the internal phase of the primary emulsion and the volume of the external phase of the secondary emulsion on yield, particle size, and encapsulation efficiency of microspheres. An increase in the volume of the internal phase of the primary emulsion resulted in a decrease in yield and encapsulation efficiency and an increase in particle size of microspheres. When the volume of the external phase of the secondary emulsion was increased, a decrease in yield, particle size, and encapsulation efficiency was observed. Microspheres with good batch-to-batch reproducibility could be produced. Scanning electron microscopic study indicated that microspheres existed as aggregates.     

Adult reserve stem cells and their potential for tissue engineering

Tissue restoration is the process whereby multiple damaged cell types are replaced to restore the histoarchitecture and function to the tissue. Several theories, have been proposed to explain the phenomenon of tissue restoration in amphibians and in animals belonging to higher order. These theories include dedifferentiation of damaged tissues, transdifferentiation of lineage-committed progenitor cells, and activation of reserve, precursor cells. Studies by Young et al. and others demonstrated that connective tissue compartments throughout postnatal individuals contain reserve precursor cells. Subsequent repetitive single cell-cloning and cell-sorting studies revealed that these reserve precursor cells consisted of multiple populations of cells, including, tissue-specific progenitor cells, germ-layer lineage stem cells, and pluripotent stem cells. Tissue-specific progenitor cells display various capacities for differentiation, ranging from unipotency (forming a single cell type) to multipotency (forming multiple cell types). However, all progenitor cells demonstrate a finite life span of 50 to 70 population doublings before programmed cell senescence and cell death occurs. Germ-layer lineage stem cells can form a wider range of cell types than a progenitor cell. An individual germ-layer lineage stem cell can form all cells types within its respective germ-layer lineage (i.e., ectoderm, mesoderm, or endoderm). Pluripotent stem cells can form a wider range of cell types than a single germ-layer lineage stem cell. A single pluripotent stem cell can form cells belonging to all three germ layer lineages. Both germ-layer lineage stem cells and pluripotent stem cells exhibit extended capabilities for self-renewal, far surpassing the limited life span of progenitor cells (50–70 population doublings). The authors propose that the activation of quiescent tissue-specific progenitor cells, germ-layer lineage stem cells, and/or pluripotent stem cells may be a potential explanation, along with dedifferentiation and transdifferentiation, for the process of tissue restoration. Several model systems are currently being investigated to determine the possibilities of using these adult quiescent reserve precursor cells for tissue engineering.     

Site-saturation mutagenesis is more efficient than DNA shuffling for the directed evolution of beta-fucosidase from beta-galactosidase

Protein engineers use a variety of mutagenic strategies to adapt enzymes to novel substrates. Directed evolution techniques (random mutagenesis and high-throughput screening) offer a systematic approach to the management of protein complexity. This sub-discipline was galvanized by the invention of DNA shuffling, a procedure that randomly recombines point mutations in vitro. In one influential study, Escherichia coli beta-galactosidase (BGAL) variants with enhanced beta-fucosidase activity (tenfold increase in k(cat)/K(M) in reactions with the novel para-nitrophenyl-beta-d-fucopyranoside substrate; 39-fold decrease in reactivity with the "native"para-nitrophenyl-beta-d-galactopyranoside substrate) were evolved in seven rounds of DNA shuffling and screening. Here, we show that a single round of site-saturation mutagenesis and screening enabled the identification of beta-fucosidases that are significantly more active (180-fold increase in k(cat)/K(M) in reactions with the novel substrate) and specific (700,000-fold inversion of specificity) than the best variants in the previous study. Site-saturation mutagenesis thus proved faster, less resource-intensive and more effective than DNA shuffling for this particular evolutionary pathway.     

Nitric Oxide–Mediated Modification of the Glycine Binding Site of the NMDA Receptor During Hypoxia in the Cerebral Cortex of the Newborn Piglet

This study tested the hypothesis that cerebral hypoxia results in nitric oxide (NO)-mediated modification of the glycine-binding site of the N-methyl-D-aspartate (NMDA) receptor. Glycine binding characteristics were determined in normoxic, hypoxic, and hypoxic with 7-nitroindazole (7-NINA)-pretreated newborn piglets. The role of nitration was evaluated by determining binding characteristics in non-nitrated and in-vitro nitrated membranes. Bmax and Kd values were 30% higher in the hypoxic group than the normoxic and 7-NINA pretreated hypoxic groups. Kd values in the in-vitro normoxic nitrated membranes were similar to the non-nitrated hypoxic group. Bmax values in the in-vitro) normoxic nitrated membrane samples were 16% lower than in the non-nitrated hypoxic group. We conclude cerebral hypoxia causes modification of the glycine-binding site of the NMDA receptor and this modification of the glycine-binding site may be NO mediated. We propose that NO-mediated modification of the glycine-binding site of the NMDA receptor regulates calcium influx through its ion-channel.     

Functional TSH receptor in human abdominal preadipocytes and orbital fibroblasts

Controversy continues about whether, and to whatlevels of abundance, thyroid-stimulating hormone receptors (TSHR) arefound in human tissues other than the thyroid gland. Restrictedexpression to the thyroid and orbit would suggest that TSHR representsthe target autoantigen in thyroid-associated ophthalmopathy. A more generalized pattern of tissue expression would be inconsistent withTSHR acting as the autoantigen that is solely responsible forselectively targeting the immune system to the orbit. We have detectedTSHR mRNA in human abdominal adipose tissue by Northern blot analysis.TSHR protein was also detected, by immunoblotting with two differentantibodies, in preadipocytes isolated from human abdominal subcutaneousand omental adipose tissue and in derivative adipocytes differentiatedin primary culture. Preadipocytes treated with thyroid-stimulatinghormone (TSH) exhibited a sevenfold increase in the activity of p70 S6kinase, a serine/threonine kinase recently recognized as a downstreamtarget of TSHR in thyroid cells. Activation of p70 S6 kinase by TSH wasalso observed in orbital fibroblasts. Thus TSHR protein expression isfound in fibroblasts from several anatomic locations, suggesting thatfactors other than site-limited TSHR expression must be involved inrestricting the distribution of Graves' disease manifestations.Furthermore, the presence of functional TSHR in preadipocytes raisesthe possibility of a novel role for TSHR signaling in adipose tissue development.

     

Feasibility of transdermal delivery of fluoxetine

Feasibility of developing a transdermal drug delivery of fluoxetine has been investigated. Permeation studies of fluoxetine across human cadaver skin were carried out using Franz diffusion cells. The receptor phase consisted of pH 7.4 phosphate buffer maintained at 37°C. Permeation enhancement of fluoxetine, either in the salt or base form, was achieved using various enhancers like azone, SR-38, and ethanol. Various O/W microemulsion systems of fluoxetine were developed to study their effect on the skin permeation of fluoxetine. The results indicated that ethanol at 65% vol/vol was able to increase the permeation of fluoxetine the most, while microemulsion systems showed decrease in the permeation of fluoxetine. The permeation of fluoxetine obtained using a 65% vol/vol ethanolic solution was found to be sufficient to deliver the required dose (20–80 mg) from a patch of feasible size. The results seem promising for developing a transdermal drug delivery system of fluoxetine. Published: September 30, 2005     

Textile dye decolorization using cyanobacteria

Cyanobacterial cultures isolated from sites polluted by industrial textile effluents were screened for their ability to decolorize cyclic azo dyes. Gloeocapsa pleurocapsoides and Phormidium ceylanicum decolorized Acid Red 97 and FF Sky Blue dyes by more than 80% after 26 days. Chroococcus minutus was the only culture which decolorized Amido Black 10B (55%). Chlorophyll a synthesis in all cultures was strongly inhibited by the dyes. Visible spectroscopy and TLC confirmed that color removal was due to degradation of the dyes.Revisions requested 10 November 2004/30 November 2004; Revisions received 16 November 2004/ 7 January 2005