The independent association between 25-hydroxyvitamin D and adiponectin and its relation with BMI in two large cohorts: the NHS and the HPFS

Low 25-hydroxyvitamin D (25(OH)D) and adiponectin levels are both associated with obesity and cardiovascular disease. Cross-sectional studies have suggested that 25(OH)D concentrations are positively associated with adiponectin, and that this relation may strengthen with increasing BMI. However, these studies had small samples sizes and did not account for many known confounders of adiponectin levels. We evaluated whether 25(OH)D was independently associated with circulating adiponectin in two large populations, and whether BMI modified this relationship. Cross-sectional analyses were performed on 1,206 women from the Nurses' Health Study I (NHS) and 439 men from the Health Professionals Follow-Up Study. Multivariable linear regression was used to analyze the independent association between 25(OH)D and adiponectin after controlling for potential confounders. Effect modification by BMI was examined by creating interaction terms between vitamin D and BMI. 25(OH)D concentrations were positively associated with circulating adiponectin in univariate analyses, and also independently associated with adiponectin after multivariable adjustments in both populations (women: β = 0.06, P < 0.001; men: β = 0.07, P < 0.05). BMI did not significantly modify the relation between 25(OH)D and adiponectin in either population. Higher 25(OH)D concentrations were independently associated with higher adiponectin concentrations in large populations of women and men. Since lower levels of 25(OH)D and adiponectin are associated with higher cardio-metabolic risk, assessing the effect of vitamin D supplementation on adiponectin levels is warranted.     

Coupled oxygen transport analysis in the avascular wall of a coronary artery stenosis during angioplasty

The coupled oxygen transport in the avascular wall of a coronary artery stenosis is studied numerically by solving the convection-diffusion equations. Two geometries replicating stenosis before and after percutaneous transluminal coronary angioplasty (PTCA) are used for the analysis. The results are compared to evaluate the effect of the degree of stenosis on oxygen transport. Important physiological aspects, such as oxygen consumption in the wall, oxygen carried by the hemoglobin, non-Newtonian viscosity of the blood, and supply of oxygen from the vasa vasorum are included. The results show that the PO2 in the medial region of the arterial wall is approximately 10mmHg. The oxygen flux to the wall increases in the flow acceleration region, whereas it decreases at the flow reattachment zone. Near the location of flow separation, there is a small rise followed by a sharp fall in the oxygen flux. The drop in the oxygen flux to the wall at the point of flow reattachment for pre-PTCA stenosis is four times that for post-PTCA stenosis. The minimum PO2 in the avascular wall, PO2,min, at this location decreases to approximately 6.0 and 4.2mmHg for post- and pre-PTCA stenosis, respectively. The drop in PO2,w and PO2,min at the point of flow reattachment for pre-PTCA is approximately 2 times that for post-PTCA stenosis. Thus, the present study quantifies the oxygen transport to the arterial wall before and after cardiovascular intervention.     

Evaluation and optimization of immobilized lipase for esterification of fatty acid and monohydric alcohol

Commercial available lipases viz. Lipozyme™, Novozyme-735 and Candida antartica lipase-B (CAL-B) were immobilized on seven different supports by simple adsorption process. The importance of suitable enzyme–support combination in esterification of lauric acid and iso-propanol was validated experimentally. Effect of long chain fatty acids (C4–C18) and small chain monohydric alcohols (C1–C6) on specific activities of different immobilized lipases were evaluated. Lauric acid (C12) was found to be the most preferred fatty acid and t-amyl alcohol (C5) being the best alcohol. CAL-B adsorbed on Lewatit was the most efficient immobilized enzyme for esterification reaction. Selectivity constant for lauric acid (3.4) was the highest among all fatty acids tested, whereas there was not much difference in selectivity between different alcohols. Furthermore, increase in fatty acid unsaturation leads to decrease catalytic efficiency of immobilized CAL-B. The optimum conditions for t-amyllaurate synthesis were as follows: lauric acid—0.5 M, t-amyl alcohol—0.3 M and amount of immobilized enzyme—150 mg. Finally, CAL-B adsorbed on Lewatit was reused for three consecutive cycles.     

Twin-core packed-bed reactors for organic-phase enzymatic esterification with water activity control

A method for the removal of water and the control of water activity, a _w, during enzymatic esterification is the use of salt hydrate pairs. When this technique is used on a laboratory scale, the recovery and reuse of the salt are not critical. Potential problems, such as the reactivity of some salts, can also be overcome simply by substituting another salt. However, if this technique is to be used on a larger scale, economic constraints would require salt recovery and restric the range of salts that could be used. In this article a twin-core packed-bed reactor — used for the esterification of an equimolar mixture of decanoic acid and dodecanol catalysed by lipase from Candida rugosa — which facilitates salt recovery and permits a _w control without direct contact between immobilized enzyme and salt, has been described. a _w control was maintained by using suitable salt hydrate mixtures in the inner core of the reactor. The substrate mixture was esterified by pumping it through the outer core of the reactor, which contained enzyme immobilized on a macroporous polypropylene support. Complete conversion, albeit at different rates, was obtained with a _w buffering at 0.48 and 0.8 by using hydrates of Na₄P₂O₇ and Na₂HPO₄.     

Mapping of a gene that regulates hemolysin production in Vibrio cholerae.

A gene that regulates the hemolysin structural gene (hly) was found to be tightly linked to the tox-1000 locus of Vibrio cholerae RJ1 and separated from hly by a large section of the V. cholerae genetic map. This hemolysin regulatory gene was designated hlyR.     

Extractive cultivation of recombinant Escherichia coli using aqueous two phase systems for production and separation of extracellular xylanase

Recombinant Escherichia coli (pATBX 1.8) secreting extracellular xylanase was used as a model system to study the application of an aqueous two phase system for extractive cultivation. An increase in the polymer concentrations from 6 to 20% in the polyethylene glycol phosphate aqueous two phase system resulted in an increase in the phase volume ratio with a concomitant decrease in the partition coefficient (K) and recovery of xylanase in the top phase. However, varying phosphate concentrations from 8 to 16% decreased both the phase volume ratio and the partition coefficient of xylanase. The polyethylene glycol (6%) and phosphate (12%) system was found to be optimum for extracellular cultivation of E. coli, where extracellular xylanase was selectively partitioned to the top phase giving a purification ratio of above 1.0. The process was extended to a semicontinuous operating mode at the optimal condition, wherein the top phase containing xylanase was recovered and the surviving cells were recycled together with the new top phase. The maximum recovery of xylanase was obtained after 12 h in the top phase with a twofold increase in the specific activity as compared to the one obtained in the reference fermentation. In the present work, we report for the first time the use of the two phase system for the extractive cultivation of recombinant E. coli (pATBX 1.8) with the purpose of obtaining a simple and inexpensive separation procedure and achieving the maximal extraction of xylanase to one phase.     

Regulation of endogenous murine mammary tumor virus expression in C57BL mouse lactating mammary glands: transcription of functional mRNA with a block at the translational level

Expression of endogenous murine mammary tumor viruses (MuMTVs) in various mouse strains is regulated in different ways, and in the absence of exogenous MuMTV, this regulation influences the incidence of spontaneous mammary tumors. Two mouse strains with low mammary tumor incidence, BALB/c and C57BL, control endogenous MuMTV expression at different stages. Neither of the strains had any detectable MuMTV polypeptides in its lactating mammary glands (LMG). However, in C57BL LMG, substantial amounts of MuMTV RNA were present, whereas very little viral RNA was detected in BALB/c LMG. By determining MuMTV RNA levels in LMG of hybrids and backcrosses of BALB/c and C57BL mice, we found that there are three unlinked, independently segregating genetic loci in C57BL mice that are responsible for the presence of moderately high amounts of MuMTV RNA in LMG. The viral RNA in C57BL LMG was processed and transported to the cytoplasm where it was found to cosediment with EDTA-sensitive polysomes. No viral proteins were detected in run-off reactions that permit completion of nascent polypeptide synthesis with polysomes from C57BL LMG, and sensitive radioimmunoassays failed to detect any MuMTV proteins in these tissues. In contrast, MuMTV mRNA purified from C57BL LMG did direct the synthesis of both gag and env MuMTV polypeptides when added to a heterologous rabbit reticulocyte lysate cell-free translation system. We propose that MuMTV mRNA in C57BL LMG, for unknown reasons, is blocked at the translational level.     

Novel histone deacetylase 8 ligands without a zinc chelating group: Exploring an ‘upside-down’ binding pose

A novel series of HDAC8 inhibitors without a zinc-chelating hydroxamic acid moiety is reported. Photoaffinity labeling and molecular modeling studies suggest that these ligands are likely to bind in an ‘upside-down’ fashion in a secondary binding site proximal to the main catalytic site. The most potent ligand in the series exhibits an IC₅₀ of 28 μM for HDAC8 and is found to inhibit the deacetylation of H4 but not α-tubulin in SH-SY5Y cell line.     

Plakophilin3 loss leads to an increase in PRL3 levels promoting K8 dephosphorylation, which is required for transformation and metastasis

The desmosome anchors keratin filaments in epithelial cells leading to the formation of a tissue wide IF network. Loss of the desmosomal plaque protein plakophilin3 (PKP3) in HCT116 cells, leads to an increase in neoplastic progression and metastasis, which was accompanied by an increase in K8 levels. The increase in levels was due to an increase in the protein levels of the Phosphatase of Regenerating Liver 3 (PRL3), which results in a decrease in phosphorylation on K8. The increase in PRL3 and K8 protein levels could be reversed by introduction of an shRNA resistant PKP3 cDNA. Inhibition of K8 expression in the PKP3 knockdown clone S10, led to a decrease in cell migration and lamellipodia formation. Further, the K8 PKP3 double knockdown clones showed a decrease in colony formation in soft agar and decreased tumorigenesis and metastasis in nude mice. These results suggest that a stabilisation of K8 filaments leading to an increase in migration and transformation may be one mechanism by which PKP3 loss leads to tumor progression and metastasis.