Biochemical Effect of Dicarboxylic Acids on Oxalate Metabolism in Experimental Rats and Studies on Oxalate Degrading Bacteria

The current study is an attempt to find a means of lowering oxalate concentration in individuals susceptible to recurrent calcium oxalate stone disease.The formation of renal stone composed of calcium oxalate is a complex process that remains poorly understood and treatment of idiopathic recurrent stone formers is quite difficult and this area has attracted lots of research workers. The main objective of this work are to study the effect of certain mono and dicarboxylic acids on calcium oxalate crystal growth in vitro, isolation and characterization of oxalate degrading bacteria, study the biochemical effect of sodium glycollate and dicarboxylic acids on oxalate metabolism in experimental stone forming rats and To investigate the effect of dicarboxylic acids on oxalate metabolism in experimental hyperoxaluric rats. Oxalic acid is one of the most highly oxidized organic compound widely distributed in the diets of man and animals, and ingestion of plants that contain high concentration of oxalate may lead to intoxication. Excessive ingestion of dietary oxalate may lead to hyperoxaluria and calcium oxalate stone disease.The formation of calcium oxalate stone in the urine is dependent on the saturation level of both calcium and oxalate. Thus the management of one or both of these ions in individuals susceptible to urolithiasis appears to be important. The control of endogenous oxalate synthesis from its precursors in hyperoxaluric situation is likely to yield beneficial results and can be a useful approach in the medical management of urinary stones. A variety of compounds have been investigated to curtain endogenous oxalate synthesis which is a crucial factor, most of these compounds have not proved to be effective in the in vivo situation and some of them are not free from the toxic effect. The non-operative management of stone disease has been practiced in ancient India in the three famous indigenous systems of medicine, Ayurveda, Unani and Siddha, and proved to be effective.However the efficiency of most of these substances is still questionable and demands further study. Man as well as other mammals cannot metabolize oxalic acid. Excessive ingestion of oxalic acid can arise from oxalate rich food and from its major metabolic precursors, glycollate, glyoxylate and ascorbic acid can lead to an acute oxalate toxicity. Increasedlevels of circulating oxalate, which can result in a variety of diseases including renal failure and oxalate lithiasis. The ability to enzymatically degrade oxalate to less noxious Isubstances, formate and CO2, could benefit a great number of individuals including those afflicted with hyperoxaluria and calcium oxalate stone disease.

Dopamine Receptor Gene Expression In Streptozotocin Induced Diabetic Rats And Its Role In Insulin Secretion

Diabetes Mellitus is a metabolic disorder associated with insulin deficiency, which not.only affects the carbohydrate metabolism but also is associated with various central and peripheral complications. Chronic hyperglycemia during diabetes mellitus is a major initiator of diabetic microvascular complications like retinopathy, neuropathy, The central nervous system (CNS) neurotransmitters play an important role in the regulation of glucose homeostasis. These neurotransmitters mediate rapid intracellular communications not only within the central nervous system but also in the peripheral tissues. They exert their function through receptors present in both neuronal and non neuronal cell surface that trigger second messenger signaling pathways. Dopamine is a neurotransmitter that has been implicated in various central neuronal degenerative disorders like Parkinson's disease and behavioral diseases like Schizophrenia. Dopamine is synthesised from tyrosine, stored in vesicles in axon terminals and released when the neuron is depolarised. Dopamine interacts with specific membrane receptors to produce its effect. Dopamine plays an important role both centrally and peripherally. The recent identification of five dopamine receptor subtypes provides a basis for understanding dopamine's central and peripheral actions . Dopamine receptors are classified into two major groups : DA D1 like and DA D2 like. Dopamine D1 like receptors consists of DA D1 and DA D5 receptors . Dopamine D2 like receptors consists of DA D2, DA D3 and DA D4 receptors. Stimulation of the DA D1 receptor gives rise to increased production of cAMP. Dopamine D2 receptors inhibit cAMP production, but activate the inositol phosphate second messenger system . Impairment of central dopamine neurotransmission causes muscle rigidity, hormonal regulation , thought disorder and cocaine addiction. Peripheral dopamine receptors mediate changes in blood flow, glomerular filtration rate, sodium excretion and catecholamine release. The dopamine D2 receptors increased in the corpus striatum and cerebral cortex but decreased in the hypothalamus and brain stem indicating their involvement in regulating insulin secretion. Dopamine D2 receptor which has a stimulatory effecton insulin secretion decreased in the pancreatic islets during diabetes. Our in vitro studies confirmed the stimulatory role of dopamine D2 receptors in stimulation of glucose induced insulin secretion. A detailed study at the molecular level on the mechanisms involved in the role of dopamine in insulin secretion, its functional modification could lead to therapeutic interventions that will have immense clinical importance.

Catalysis by some metal oxides modified with phosphate ions

Surface acidity of phosphate modified La2O3,CeO2 and SnO2 has been estimated by titrimetric Method using Hammett Indicators.Mixed Oxides of tin and lanthanum have also been prepared and subjected to phosphate modification.Surface characterizartion of the samples has been carried out using XRD, surface area,thermal analysis and IR spectroscopy. Phosphate content in the samples has been chemically estimated. The catalytic activity for benzylation and esterification reaction has also been investigated.

Surface properties and catalytic activity of phosphate modified zirconia

Preparation and physico-chemical characterization or phosphate modified zirconia systems and their application to Friedel-Crafts benzylation and benzoylation of toluene have been reported. The influence of transition metals on the surface properties and catalytic activity has also been discussed.

Photoacoustic Thermal Characterization of Porous Rare-Earth Phosphate Ceramics

The laser induced non-destructive photoacoustic technique has been employed to measure the thermal diffusivity of lanthanum phosphate ceramics prepared by the sol–gel route. The thermal diffusivity value was evaluated by knowing the transition frequency between the thermally thin to thermally thick region from the log–log plot of photoacoustic amplitude versus chopping frequency. Analysis of the data was carried out on the basis of the one-dimensional model of Rosencwaig and Gersho. The present investigation reveals that the sintering temperature has great influence on the propagation of heat carriers and hence on the thermal diffusivity value. The results were interpreted in terms of variations in porosity with sintering temperature as well as with changes in grain size.

Electrical conductivity, dielectric constant and phase transitions in pure and doped diammonium hydrogen phosphate

DC and AC electrical conductivity measurements in single crystals of diammonium hydrogen phosphate along the c axis show anomalous variations at 174, 246 and 416 K. The low-frequency dielectric constant also exhibits peaks exactly at these temperatures with a thermal hysteresis of 13 degrees C for the peak at 416 K. These specific features of the electrical properties are in agreement with earlier NMR second-moment data and can be identified with three distinct phase transitions that occur in the crystal. The electrical conductivity values have been found to increase linearly with impurity concentration in specimens doped with a specific amount of SO42- ions. The mechanisms of the phase transition and of the electrical conduction process are discussed in detail.

High‐temperature phase transitions in pure and deuterated ammonium dihydrogen phosphate: Conductivity and dielectric measurements

Results of axiswise measurements of the electrical conductivity (dc and ac) and dielectric constant of NH4H2PO4 confirm the occurrence of the recently suggested high‐temperature phase transition in this crystal (at 133 °C). The corresponding transition in ND4D2PO4 observed here for the first time takes place at 141.5 °C. The mechanism involved in these transitions and those associated with the electrical conduction and dielectric anomalies are explained on the basis of the motional effects of the ammonium ions in these crystals. Conductivity values for deuterated crystals give direct evidence for the predominance of protonic conduction throughout the entire range of temperatures studied (30–260 °C).

The influence of organophosphorus pesticide-methylparathion on protein, lipid metabolism and detoxifying enzymes in rohu (Labeo rohita)

Methylparathion (MP) is an organophosphorus insecticide used world wide in agriculture due to its high activity against a broad spectrum of insect pests. The aim of the study is to understand the effect of methylparathion on the lipid peroxidation, detoxifying and antioxidant enzymes namely catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione Stransferase (GST), total reduced glutathione (GSH), lipid peroxidation (LPO), acetylcholinesterase (AChE) and disease diagnostic marker enzymes in liver, sarcoplasmic (SP) and myofirbirllar (MF) proteins in muscles, lipids and histopathlogical changes in various organs of Labeo rohita of size 75 i 6g at lethal and sublethal level of exposure. The probit analysis showed that the lethal concentration (LC 50%) for 24, 48, 72 and 96h were 15.5mg/L, 12.3mg/L, 11.4mg/L and 10.2mg/L respectively which is much higher compared to the LC50 for juvenile fish. The LPO level and GST activity increased five folds and two folds respectively on exposure to methylparathion at 10.2 mg/L and the level of the enzymes increased, on sub lethal exposure beyond 0.25mg/L. AChE activity was inhibited by 74% at a concentration of 1.8mg/L and 90% at 5.4mg/L. The disease diagnostic marker enzymes AST, ALT, ALP and LDH increased by about 2, 3 ,3 and 2 folds respectively at pesticide concentration of 10.2mg/L when compared to control. On sub lethal exposure, however the enzymes did not show any significant changes up to 0.5mg/L. At a concentration of 10.2 mg/L, there was a three fold increase in myofibrillar proteins while the increase in sarcoplasmic protein was above 1.5 fold. On sub lethal exposure, significant alteration was noticed up to 30 days up to 1mg/L of methylparathion concentration. Further exposure up to 45 days increased sarcoplasmic proteins (upto 0.5mg/L). ln the case of myofibrillar proteins, noticeable changes were observed at 1mg/L concentration right from 15th day. The cholesterol content in brain tissues increased by about 27% at methylparathion concentration of 5.4 mglL. However at 0.25mg/L sub lethal concentration, no significant alteration was observed in enzyme activity, muscle proteins, lipids and histopathology of the tissues. The results suggest that methylparathion has the potential to induce oxidative stress in fish, and that liver, muscle and brains are more sensitive organs of Labeo rohita, with poor antioxidant potentials at higher concentrations of the pesticide. The various parameters studied in this investigation can also be used as biomarkers of methylparathion exposure.

Sequential interactions of Silver-silica nanocomposite (Ag-SiO2NC) with cell wall, metabolism and genetic stability of Psedomonas aeruginosa, a multiple antibiotic resistant bacterium

The study was carried out to understand the effect of silver-silica nanocomposite (Ag-SiO2NC) on the cell wall integrity, metabolism and genetic stability of Pseudomonas aeruginosa, a multiple drugresistant bacterium. Bacterial sensitivity towards antibiotics and Ag-SiO2NC was studied using standard disc diffusion and death rate assay, respectively. The effect of Ag-SiO2NC on cell wall integrity was monitored using SDS assay and fatty acid profile analysis while the effect on metabolism and genetic stability was assayed microscopically, using CTC viability staining and comet assay, respectively. P. aeruginosa was found to be resistant to β-lactamase, glycopeptidase, sulfonamide, quinolones, nitrofurantoin and macrolides classes of antibiotics. Complete mortality of the bacterium was achieved with 80 μgml-1 concentration of Ag-SiO2NC. The cell wall integrity reduced with increasing time and reached a plateau of 70 % in 110 min. Changes were also noticed in the proportion of fatty acids after the treatment. Inside the cytoplasm, a complete inhibition of electron transport system was achieved with 100 μgml-1 Ag-SiO2NC, followed by DNA breakage. The study thus demonstrates that Ag-SiO2NC invades the cytoplasm of the multiple drug-resistant P. aeruginosa by impinging upon the cell wall integrity and kills the cells by interfering with electron transport chain and the genetic stability

Characterization of Lipid Droplets and Functional Analysis of Lipid Droplet-Associated Proteins in Dictyostelium discoideum

Lipid droplets (LDs) are the universal storage form of fat as a reservoir of metabolic energy in animals, plants, bacteria and single celled eukaryotes. Dictyostelium LD formation was investigated in response to the addition of different nutrients to the growth medium. LDs were induced by adding exogenous cholesterol, palmitic acid (PA) as well as growth in bacterial suspension, while glucose addition fails to form LDs. Among these nutrients, PA addition is most effective to stimulate LD formation, and depletion of PA from the medium caused LD degradation. The neutral lipids incorporated into the LD-core are composed of triacylglycerol (TAG), steryl esters, and an unknown neutral lipid (UKL) species when the cells were loaded simultaneously with cholesterol and PA. In order to avoid the contamination with other cellular organelles, the LD-purification method was modified. The isolated LD fraction was analysed by mass spectrometry and 100 proteins were identified. Nineteen of these appear to be directly involved in lipid metabolism or function in regulating LD morphology. Together with a previous study, a total of 13 proteins from the LD-proteome were confirmed to localize to LDs after the induction with PA. Among the identified LD-proteins, the localization of Ldp (lipid droplet membrane protein), GPAT3 (glycerol-3-phosphate acyltransferase 3) and AGPAT3 (1-acylglycerol-3-phosphate-acyltransferase 3) were further verified by GFP-tagging at the N-termini or C-termini of the respective proteins. Fluorescence microscopy demonstrated that PA-treatment stimulated the translocation of the three proteins from the ER to LDs. In order to clarify DGAT (diacylglycerol acyltransferase) function in Dictyostelium, the localization of DGAT1, that is not present in LD-proteome, was also investigated. GFP-tagged DGAT1 localized to the ER both, in the presence and absence of PA, which is different from the previously observed localization of GFP-tagged DGAT2, which almost exclusively binds to LDs. The investigation of the cellular neutral lipid level helps to elucidate the mechanism responsible for LD-formation in Dictyostelium cells. Ldp and two short-chain dehydrogenases, ADH (alcohol dehydrogenase) and Ali (ADH-like protein), are not involved in neutral lipid biosynthesis. GPAT, AGPAT and DGAT are three transferases responsible for the three acylation steps of de novo TAG synthesis. Knock-out (KO) of AGPAT3 and DGAT2 did not affect storage-fat formation significantly, whereas cells lacking GPAT3 or DGAT1 decreased TAG and LD accumulation dramatically. Furthermore, DGAT1 is responsible for the accumulation of the unknown lipid UKL. Overexpression of DGAT2 can rescue the reduced TAG content of the DGAT1-KO mutant, but fails to restore UKL content in these cells, indicating that of DGAT1 and DGAT2 have overlapping functions in TAG synthesis, but the role in UKL formation is unique to DGAT1. Both GPAT3 and DGAT1 affect phagocytic activity. Mutation of GPAT3 increases it but a DGAT1-KO decreases phagocytosis. The double knockout of DGAT1 and 2 also impairs the ability to grow on a bacterial lawn, which again can be rescued by overexpression of DGAT2. These and other results are incorporated into a new model, which proposes that up-regulation of phagocytosis serves to replenish precursor molecules of membrane lipid synthesis, whereas phagocytosis is down-regulated when excess fatty acids are used for storage-fat formation.  

Effects of Tithonia diversifolia, farmyard manure and urea, and phosphate fertiliser application methods on maize yields in western Kenya

Maize production in western Kenya is often limited by deficiencies of nitrogen and phosphorus. We assessed the effectiveness of Tithonia diversifolia green manure (tithonia), farmyard manure (FYM) and urea as sources of nitrogen (N) for maize when inorganic phosphorus (P) fertiliser was either broadcast (BR) or spot-placed in the planting hole (SP) for two consecutive seasons; October to December of 1998 and April to August of 1999 at two sites; Nyabeda and Khwisero in western Kenya. A randomised complete block design with four replications was used. Maize yields were higher at Nyabeda and responded to P application better than at Khwisero. At the same N rate, tithonia and FYM were as effective as urea in increasing maize yields at both sites. There were no significant differences in maize yields when phosphate fertiliser was either BR or SP regardless of the N source used in the first season. However, in the second season, the residual yields for the BR treatments were consistently higher than those of the SP. Our results suggest that tithonia and FYM can substitute for urea as N sources and that fertiliser P should be broadcast and incorporated together with the organic materials at the time of planting to save on labour costs.

Búsqueda de selección en el polimorfismo 677C>T (c.665C>T) del gen de la metilentetrahidrofolato reductasa (MTHFR) en una población Colombiana

Se realizó un estudio genético – poblacional en dos grupos etarios de población colombiana con la finalidad de evaluar las diferencias genéticas relacionadas con el polimorfismo MTHFR 677CT en busca de eventos genéticos que soporten la persistencia de este polimorfismo en la especie humana debido que este ha sido asociado con múltiples enfermedades. De esta manera se genotipificaron los individuos, se analizaron los genotipos, frecuencias alélicas y se realizaron diferentes pruebas genéticas-poblacionales. Contrario a lo observado en poblaciones Colombianas revisadas se identificó la ausencia del Equilibrio Hardy-Weinberg en el grupo de los niños y estructuras poblacionales entre los adultos lo que sugiere diferentes historias demográficas y culturales entre estos dos grupos poblacionales al tiempo, lo que soporta la hipótesis de un evento de selección sobre el polimorfismo en nuestra población. De igual manera nuestros datos fueron analizados junto con estudios previos a nivel nacional y mundial lo cual sustenta que el posible evento selectivo es debido a que el aporte de ácido fólico se ha incrementado durante las últimas dos décadas como consecuencia de las campañas de fortificación de las harinas y suplementación a las embarazadas con ácido fólico, por lo tanto aquí se propone un modelo de selección que se ajusta a los datos encontrados en este trabajo se establece una relación entre los patrones nutricionales de la especie humana a través de la historia que explica las diferencias en frecuencias de este polimorfismo a nivel espacial y temporal.  

Immunomodulation and metabolism: possible role of lactoferrin

To gain insight in the relationship between innate immune system and metabolic disease, we aimed to investigate the effects of lactoferrin in obesity-related metabolic disturbances. Circulating lactoferrin concentration was significantly decreased in subjects with altered glucose tolerance (AGT) and associated negatively with obesity-related metabolic disturbances. The SNPs-induced aminoacidic changes in lactoferrin N-terminus region were associated with a low atherogenic lipid profile. Lactoferrin production in neutrophils decreased significatively in aging, chronic low-grade inflammation and type 2 diabetes. In vitro, lactoferrin increased insulin signaling pathway, even under insulin resistance conditions and displayed dual effects on adipogenesis (antiadipogenic in 3T3-L1 and adipogenic in human adipocytes). In conclusion, lactoferrin might play a potential protective role against insulin resistance and obesity related metabolic disturbances.