Downregulation of the renal outer medullary K+ channel ROMK by the AMP-activated protein kinase

The 5′-adenosine monophosphate-activated serine/threonine protein kinase (AMPK) is stimulated by energy depletion, increase in cytosolic Ca²⁺ activity, oxidative stress, and nitric oxide. AMPK participates in the regulation of the epithelial Na⁺ channel ENaC and the voltage-gated K⁺ channel KCNE1/KCNQ1. It is partially effective by decreasing PIP₂ formation through the PI3K pathway. The present study explored whether AMPK regulates the renal outer medullary K⁺ channel ROMK. To this end, cRNA encoding ROMK was injected into Xenopus oocytes with and without additional injection of constitutively active AMPK^γR70Q (AMPK^α1-HA+AMPK^β1-Flag+AMPKγ1^R70Q), or of inactive AMPK^αK45R (AMPK^α1K45R+AMPK^β1-Flag+AMPK^γ1-HA), and the current determined utilizing two-electrode voltage-clamp and single channel patch clamp. ROMK protein abundance was measured utilizing chemiluminescence in Xenopus oocytes and western blot in whole kidney tissue. Moreover, renal Na⁺ and K⁺ excretion were determined in AMPK^α1-deficient mice (ampk ^?/? ) and wild-type mice (ampk ^+/+ ) prior to and following an acute K⁺ load (111 mM KCl, 30 mM NaHCO₃, 4.7 mM NaCl, and 2.25 g/dl BSA) at a rate of 500 μl/h. As a result, coexpression of AMPK^γR70Q but not of AMPK^αK45R significantly decreased the current in ROMK1-expressing Xenopus oocytes. Injection of phosphatidylinositol PI_(4,5)P₂ significantly increased the current in ROMK1-expressing Xenopus oocytes, an effect reversed in the presence of AMPK^γR70Q. Under control conditions, no significant differences between ampk ^?/? and ampk ^+/+ mice were observed in glomerular filtration rate (GFR), urinary flow rate, serum aldosterone, plasma Na⁺, and K⁺ concentrations as well as absolute and fractional Na⁺ and K⁺ excretion. Following an acute K⁺ load, GFR, urinary flow rate, serum aldosterone, plasma Na⁺, and K⁺ concentration were again similar in both genotypes, but renal absolute and fractional Na⁺ and K⁺ excretion were higher in ampk ^?/? than in ampk ^+/+ mice. According to micropuncture following a K⁺ load, delivery of Na⁺ to the early distal tubule but not delivery of K⁺ to late proximal and early distal tubules was increased in ampk ^?/? mice. The upregulation of renal ROMK1 protein expression by acute K⁺ load was more pronounced in ampk ^?/? than in ampk ^+/+ mice. In conclusion, AMPK downregulates ROMK, an effect compromising the ability of the kidney to excrete K⁺ following an acute K⁺ load.     

Foliar Application of Seaweed Sap Enhances Growth,Yield and Quality of Maize in Eastern Himalayas

Maize (Zea mays L.) productivity in hilly regions of North Eastern Region (NER) of India is very low due to limited use of manures and fertilizers. Under such situation, seaweed sap can become an alternative as it is an organic bio-stimulant. Experiment with extracts from marine algae Kappaphycus alvarezii (K sap) and Gracilaria edulis (G sap) was conducted during 2012 and 2013 to assess the efficacy of seaweed saps on growth, productivity and quality of maize and their role in economizing the chemical fertilizer requirement. Results revealed that K or G sap @ 10% and above concentrations along with 100% recommended dose of fertilizer (RDF) recorded significantly higher plant height, dry matter, chlorophyll content, yield attributes and yield of maize compared to control (water spray). The nitrogen (N) and protein content in grain was the highest under 15% K sap + 100% RDF followed by 15% G sap + 100% RDF. Application of K or G sap at 10% concentrations + 100% RDF also significantly increased micronutrient (copper, zinc, manganese and iron) concentrations in maize grains. The available nitrogen, phosphorous and potassium content in soil was recorded to be lowest under 7.5% K sap + 50% RDF. Thus, foliar application of 10% K or G sap along with 100% RDF is recommended for sustainable maize production in NER of India and other ecosystems elsewhere.

     

Antiarthritic activity of various extracts of Mesua ferrea Linn. seed

Ethnopharmacological relevance

Mesua ferrea Linn. (Cluciaseae), Cobra's saffron, is named after the heaviness of its timber and is cultivated in tropical climates for its form, foliage, and fragrant flowers. It is prescribed in the Ayurvedic literature for the treatment of pain, inflammation, and rheumatic conditions.

Objective

In present investigation, activity of Mesua ferrea and its evaluation in the formaldehyde and Complete Freund's Adjuvant (CFA)-induced arthritis in rats is reported.

Materials and methods

The extracts obtained from successive extraction were subjected to preliminary phytochemical investigation and antiarthritic activity was evaluated by inducing formaldehyde and CFA. Body weight changes and haematological parameters were measured.

Results

The results indicate that Mesua ferrea protects rats against formaldehyde and CFA induced arthritis. The body weight changes and haematological perturbations induced by CFA were maintained. The overall results indicated that Mesua ferrea exerts a potent protective effect against formaldehyde and adjuvant-induced arthritis in rats.

Conclusion

These findings demonstrate that the present study validates the ethnomedicinal use of seeds of Mesua ferrea in the treatment of arthritis conditions.     

Pharmacokinetic/pharmacodynamic profiling of imipenem in patients admitted to an intensive care unit in India: A nonrandomized,cross-sectional,analytical, open-labeled study

Results:The difference in the plasma imipenem concentration between the gastrointestinal and the nongastrointestinal groups was significant at 2 h (P = 0.015) following drug dosing; while the difference was significant between the skin/cellulitis and nonskin/cellulitus groups at 2 h (P = 0.008), after drug dosing. The imipenem levels were above the MIC and 5 times the MIC for the isolated organism in 96.67% and 50% of the patients, respectively.Conclusions:The pharmacokinetic profile of imipenem does not vary according to the locus of an infection in critically ill patients. Imipenem, 3 g/day intermittent dosing, maintains a plasma concentration which is adequate to treat most infections encountered in patients admitted to an ICU. However, a change in the dosing regimen is suggested for patients infected with organisms having MIC values above 4 mg/L.     

Reduction of ER stress via a chemical chaperone prevents disease phenotypes in a mouse model of primary open angle glaucoma

Mutations in myocilin (MYOC) are the most common genetic cause of primary open angle glaucoma (POAG), but the mechanisms underlying MYOC-associated glaucoma are not fully understood. Here, we report the development of a transgenic mouse model of POAG caused by the Y437H MYOC mutation; the mice are referred to herein as Tg-MYOC(Y437H) mice. Analysis of adult Tg-MYOC(Y437H) mice, which we showed express human MYOC containing the Y437H mutation within relevant eye tissues, revealed that they display glaucoma phenotypes (i.e., elevated intraocular pressure [IOP], retinal ganglion cell death, and axonal degeneration) closely resembling those seen in patients with POAG caused by the Y437H MYOC mutation. Mutant myocilin was not secreted into the aqueous humor but accumulated in the ER of the trabecular meshwork (TM), thereby inducing ER stress in the TM of Tg-MYOC(Y437H) mice. Furthermore, chronic and persistent ER stress was found to be associated with TM cell death and elevation of IOP in Tg-MYOC(Y437H) mice. Reduction of ER stress with a chemical chaperone, phenylbutyric acid (PBA), prevented glaucoma phenotypes in Tg-MYOC(Y437H) mice by promoting the secretion of mutant myocilin in the aqueous humor and by decreasing intracellular accumulation of myocilin in the ER, thus preventing TM cell death. These results demonstrate that ER stress is linked to the pathogenesis of POAG and may be a target for treatment in human patients.     

Production of a highly potent epoxide through the microbial metabolism of 3β-acetoxyurs-11-en-13β,28-olide by Aspergillus niger culture

Context 3β-Acetoxyurs-11-en-13β,28-olide (I), a triterpenoid, is found in most plant species. Pharmacologically triterpenes are very effective compounds with potent anticancer, anti-HIV and antimicrobial activities.

Objectives Microbial transformation of 3β-acetoxyurs-11-en-13β,28-olide (I) was performed in order to obtain derivatives with improved pharmacological potential.

Materials and methods Compound (I, 100?mg) was incubated with Aspergillus niger culture for 12 d. The metabolite formed was purified through column chromatography. Structure elucidation was performed through extensive spectroscopy (IR, MS and NMR). In vitro α- and β-glucosidase inhibitory, and antiglycation potentials of both substrate and metabolite were evaluated.

Results Structure of metabolite II was characterized as 3β-acetoxyurs-11,12-epoxy-13β,28-olide (II). Metabolite II was found to be an oxidized product of compound I. In vitro α- and β-glucosidases revealed that metabolite II was a potent and selective inhibitor of α-glucosidase (IC₅₀ value?=?3.56?±?0.38?μM), showing that the inhibitory effect of metabolite II was far better than compound I (IC₅₀ value?=?14.7?±?1.3?μM) as well as acarbose (IC₅₀ value?=?545?±?7.9?μM). Antiglycation potential of compound II was also high with 82.51?±?1.2% inhibition. Thus, through oxidation, the biological potential of the substrate molecule can be enhanced.

Conclusion Biotransformation can be used as a potential tool for the production of biologically potent molecules.     

Activation of the BMP canonical signaling pathway in human optic nerve head tissue and isolated optic nerve head astrocytes and lamina cribrosa cells

PURPOSE: Bone morphogenetic proteins (BMPs) are members of the transforming growth factor (TGF)-beta superfamily that controls multiple functions in a variety of cells. We have previously shown that human optic nerve head (ONH) astrocytes and lamina cribrosa (LC) cells express BMP and BMP receptor mRNA and proteins. The purpose of the present study was to determine whether human ONH tissues express the canonical BMP signaling pathway and whether ONH cells secrete BMP-4 and respond to exogenous BMP-4 through this pathway. METHODS: Well-characterized human ONH astrocytes (N = 2) and LC cells (N = 3) were treated with exogenous BMP-4 (20 ng/mL) for various times. Western immunoblot analysis was used to detect secreted BMP-4 in serum-free conditioned media of ONH cells and in human ONH tissues (N = 4) and Smad proteins in total cell lysate of ONH cells and tissues. Intracellular colocalization of p-R-Smad1 with Co-Smad4 and localization of inhibitory Smads (e.g., I-Smad6 and I-Smad7) were studied through immunocytochemistry. In addition, coimmunoprecipitation was used to verify the interaction of p-R-Smad1 with Co-Smad4. RESULTS: ONH astrocytes and LC cells secrete BMP-4 and synthesize R-Smad1, R-Smad5, I-Smad6, I-Smad7, and Co-Smad4 proteins. Exposure to BMP-4 for either 10 or 60 minutes resulted in increased p-R-Smad1 and p-R-Smad1/5/8 protein levels that declined after 12 hours of treatment. Immunocytochemistry and coimmunoprecipitation studies revealed that p-R-Smad1/5/8 and Co-Smad4 interact and colocalize in the nucleus. BMP-4 treatment resulted in increased coprecipitation of p-R-Smad1/5/ 8 and Co-Smad4. I-Smad6 and I-Smad7 are localized in the nucleus and cytoplasm of ONH astrocytes and LC cells. Proteins for BMP-4, p-R-Smad1/5/8, R-Smad1, R-Smad5, R-Smad8, and Co-Smad4 are present in human ONH tissues. In addition, phosphorylated Smad1 and Smad5 colocalize with Smad4 in the nuclei of ONH tissues. CONCLUSIONS: These results indicate that BMP-4 and Smad signaling proteins are present in human ONH tissues, isolated ONH astrocytes, and LC cells. In addition, exogenous BMP-4 treatment of ONH astrocytes and LC cells results in downstream signaling through the canonical Smad pathway. Thus, cells within the human ONH may respond to locally released BMP through paracrine or autocrine mechanisms.