Endothelin-1 reduces mesenteric microvascular hydraulic permeability via cyclic AMP and protein kinase A signal transduction

We have previously shown that endothelin-1 (ET-1) decreases microvascular hydraulic permeability. In this study, we tested the hypothesis that ET-1 exerts its permeability-decreasing effect through cAMP, cGMP, and protein kinase A (PKA) by determining the effect of ET-1 on venular fluid leak during inhibition of cAMP synthesis, inhibition of cGMP degredation, and inhibition of PKA. Rat mesenteric venules were cannulated to measure hydraulic permeability, L(p) (units x 10(-7)cm/(s cmH(2)O)). L(p) was measured during continuous perfusion of 80 pM ET-1 and either (1) an inhibitor of cAMP synthesis (10 microM 2',5'ddA), (2) an inhibitor of cGMP degradation (100 microM Zaprinast), or (3) an inhibitor of PKA (10 microM H-89). Inhibition of cAMP synthesis blocked the permeability decreasing effects of ET-1. The peak L(p) of the cAMP inhibitor alone and with ET-1 was 4.11+/-0.53 and 3.86+/-0.19, respectively (p=0.36, n=6). Inhibition of cGMP degradation did not block the permeability decreasing effects of ET-1. The peak L(p) during inhibition of cGMP degradation alone and with ET-1 was 2.26+/-0.15 and 1.44+/-0.09, respectively (p<0.001, n=6). Inhibition of PKA activation blocked the permeability decreasing effects of ET-1. The peak L(p) of the PKA inhibitor alone and with ET-1 was 2.70+/-0.15 and 2.59+/-0.15, respectively (p=0.38, n=6). The data support the notion that the signal transduction mechanism of ET-1 with regard to decreasing microvascular fluid leak involves cAMP production and PKA activation, but not cGMP degradation. Further understanding of intracellular mechanisms that control microvascular fluid leak could lead to the development of a pharmacologic therapy to control third space fluid loss in severely injured or septic patients.     

Does Swimming Exercise Affect Experimental Chronic Kidney Disease in Rats Treated with Gum Acacia?

Different modes of exercise are reported to be beneficial in subjects with chronic kidney disease (CKD). Similar benefits have also been ascribed to the dietary supplement gum acacia (GA). Using several physiological, biochemical, immunological, and histopathological measurements, we assessed the effect of swimming exercise (SE) on adenine –induced CKD, and tested whether SE would influence the salutary action of GA in rats with CKD. Eight groups of rats were used, the first four of which were fed normal chow for 5 weeks, feed mixed with adenine (0.25% w/w) to induce CKD, GA in the drinking water (15% w/v), or were given adenine plus GA, as above. Another four groups were similarly treated, but were subjected to SE during the experimental period, while the first four groups remained sedentary. The pre-SE program lasted for four days (before the start of the experimental treatments), during which the rats were made to swim for 5 to 10 min, and then gradually extended to 20 min per day. Thereafter, the rats in the 5^th, 6^th, 7^th, and 8^th groups started to receive their respective treatments, and were subjected to SE three days a week for 45 min each. Adenine induced the typical signs of CKD as confirmed by histopathology, and the other measurements, and GA significantly ameliorated all these signs. SE did not affect the salutary action of GA on renal histology, but it partially improved some of the above biochemical and physiological analytes, suggesting that addition of this mode of exercise to GA supplementation may improve further the benefits of GA supplementation.     

Sodium and boron exclusion in two Brassica juncea cultivars exposed to the combined treatments of salinity and boron at moderate alkalinity

Salinity and high boron (B) concentrations are important co-limitations to crop production on naturally occurring alkaline soils in low rainfall regions of the world. Although the interactive effects of salinity and B toxicity on Brassica juncea growth have been reported in slightly acidic soils, very little is known about the interactive effects in alkaline soils. In the current study, a moderately tolerant (Vaibhav) and sensitive (Xinyou5) variety, were grown hydroponically for four weeks to assess mild salinity (50 mM NaCl) with or without high B (1 mM B) at moderate alkalinity (pH 8.5/5 mM NaHCO₃). The growth of the two varieties was more affected under the combined treatment than either salinity or high B alone. Although growth rate reduction was similar among the varieties, Vaibhav maintained a lower sodium (Na) and B and a higher potassium (K) concentration in the leaves than Xinyou5. In response to salinity, Vaibhav demonstrated essential tolerance mechanisms of partial exclusion and presumably compartmentalization of Na, leading to greater biomass than Xinyou5. Despite being able to better exclude B, Xinyou5 suffered a greater growth penalty, indicating higher B sensitivity than Vaibhav. In conclusion, screening for individual stresses is not necessarily the best strategy because plant responses to a single stress either salinity or high B may not always be the same as observed when both stresses are present together. Therefore, Brassica germplasm screening is essential for stresses in combination but not separately.     

Estimation of pH effect on the structure and stability of kinase domain of human integrin-linked kinase

Integrin-linked kinase (ILK) is an evolutionarily conserved Ser/Thr protein kinase, involved in many physiological functions such as signal transduction, actin rearrangement, cell proliferation, migration, polarisation, angiogenesis and apoptosis. An increased expression of ILK is associated with different cancers and thus considered as an attractive target for cancer therapy. We have successfully cloned, expressed and purified the kinase domain (193–446 residues) of ILK. To see the effect of pH on the structure and conformation, we performed circular diachroism, fluorescence and absorbance measurements in a wide range of pH conditions. We observed that within the range of pH 7.5–11.0, ILK_193–446 maintains its both secondary and tertiary structures. While visible aggregates were observed under the acidic pH 2.0–5.5 conditions, in order to complement these observations, we have performed molecular dynamics simulations of this kinase domain by mimicking diverse pH conditions which enabled us to see conformational preferences of the protein under such conditions. A significant correlation between the spectroscopic and molecular dynamics simulation was observed. These findings are useful to understand the conformation of ILK protein under certain pH condition which may be further implicated in the drug design and discovery.     

Emerging roles of microRNAs in regulating the mTOR signaling pathway during tumorigenesis

The mammalian target of rapamycin (mTOR) is a large Ser/Thr protein kinase that belongs to the phosphoinositide 3-kinase (PI3K) family and mediates various physiological and pathological processes, especially cell proliferation, protein synthesis, autophagy, and cancer development. The mTOR expression is transient and tightly regulated in normal cells, but it is overactivated in cancer cells. Recently, several studies have indicated that microRNAs (miRNAs) play a critical role in the regulation of mTOR and mTOR-associated processes, some acting as inhibitors and the others as activators. Although it is still in infancy, the strategy of combining both miRNAs and mTOR inhibitors might provide an approach to selectively sensitizing tumor cells to chemotherapy-induced DNA damage and subsequently attenuating the tumor cell growth and apoptosis.     

Testing polyols' compatibility with Gibbs energy of stabilization of proteins under conditions in which they behave as compatible osmolytes

It is generally believed that compatible osmolytes stabilize proteins by shifting the denaturation equilibrium, native state <--> denatured state toward the left. We show here that if osmolytes are compatible with the functional activity of the protein at a given pH and temperature, they should not significantly perturb this denaturation equilibrium under the same experimental conditions. This conclusion was reached from the measurements of the activity parameters (K(m) and k(cat)) and guanidinium chloride-induced denaturations of lysozyme and ribonuclease-A in the presence of five polyols (sorbitol, glycerol, mannitol, xylitol and adonitol) at pH 7.0 and 25 degrees C.     

Plant growth promoting activity of an auxin and siderophore producing isolate of <Emphasis Type="Italic">Streptomyces</Emphasis> under saline soil conditions

A biocontrol Streptomyces isolate (C) was tested for its plant growth promoting qualities under saline conditions. Exposure to elevated osmotic strengths up to 300 mM NaCl increased dry weight and cfu/ml significantly. The isolate C produced indolyl-3-acetic acid (IAA) into the medium in the amount of 2.4 μg/ml. The amount of auxin increased after adding salt and reached to 4.7 μg/ml in 300 mM NaCl. Biosynthesis of siderophore was detectable and increased in presence of NaCl. Streptomyces isolate C showed good solubilization of tricalcium phosphate in culture medium with 92 mg/l. Solubilization decreased in presence of NaCl. Soil treatment with isolate C increased the growth and development of wheat plant in normal and saline conditions. In this treatment there were significant increases in germination rate, percentage and uniformity, shoot length and dry weight compared to the control. Applying the bacterial inocula increased the concentration of N, P, Fe and Mn in wheat shoots grown in normal and saline soil, but had non-significant effect on other micro and macronutrients concentrations. Results of this study show that Streptomyces isolate C has potential to be utilized as biofertilizer in saline soils.     

Differentiation and regenerative capacities of human odontoma-derived mesenchymal cells

Regenerating human tooth ex vivo and biological repair of dental caries are hampered by non-viable odontogenic stem cells that can regenerate different tooth components. Odontoma is a developmental dental anomaly that may contain putative post-natal stem cells with the ability to differentiate and regenerate in vivo new dental structures that may include enamel, dentin, cementum and pulp tissues. We evaluated odontoma tissues from 14 patients and further isolated and characterized human odontoma-derived mesenchymal cells (HODCs) with neural stem cell and hard tissue regenerative properties from a group of complex odontoma tissues from 1 of 14 patients. Complex odontoma was more common (9 of 14) than compound type and females (9 of 14) were more affected than males in our set of patients. HODCs were highly proliferative like dental pulp stem cells (DPSCs) but demonstrated stronger neural immunophenotype than both DPSCs and mandible bone marrow stromal cells (BMSCs) by expressing higher levels of nestin, Sox 2 and βIII-tubulin. When transplanted with hydroxyapatite/tricalcium phosphate into immunocompromised mice, HODCs differentiated and regenerated calcified hard tissues in vivo that were morphologically and quantitatively comparable to those generated by DPSCs and BMSCs. When transplanted with polycaprolactone (biodegradable carrier), HODCs differentiated to form new predentin on the surface of a dentin platform. Newly formed predentin contained numerous distinct dentinal tubules and an apparent dentin–pulp arrangement. HODCs represent unique odontogenic progenitors that readily commit to formation of dental hard tissues.     

Embryonic Microglia Interact with Hypothalamic Radial Glia during Development and Upregulate the TAM Receptors MERTK and AXL following an Insult

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