Hydrothermally Grown Globosa-like TiO2 Nanostructures for Effective Photocatalytic Dye Degradation and LPG Sensing.

The rapid expansion of industrial activities has resulted in severe environmental pollution manifested by organic dyes discharged from the food, textile, and leather industries, as well as hazardous gas emissions from various industrial processes. Titanium dioxide (TiO2)-nanostructured materials have emerged as promising candidates for effective photocatalytic dye degradation and gas sensing applications owing to their unique physicochemical properties. This study investigates the development of a photocatalyst and a liquefied petroleum gas (LPG) sensor using hydrothermally synthesized globosa-like TiO2 nanostructures (GTNs). The synthesized GTNs are then evaluated to photocatalytically degrade methylene blue dye, resulting in an outstanding photocatalytic activity of 91% degradation within 160 min under UV light irradiation. Furthermore, these nanostructures are utilized to sense liquefied petroleum gas, which attains a superior sensitivity of 7.3% with high response and recovery times and good reproducibility. This facile and cost-effective hydrothermal method of fabricating TiO2 nanostructures opens a new avenue in photocatalytic dye degradation and gas sensing applications.

Pred-MutHTP: Prediction of disease-causing and neutral mutations in human transmembrane proteins.

Membrane proteins are unique in that segments thereof concurrently reside in vastly different physicochemical environments: the extracellular space, the lipid bilayer, and the cytoplasm. Accordingly, the effects of missense variants disrupting their sequence depend greatly on the characteristics of the environment of the protein segment affected as well as the function it performs. Because membrane proteins have many crucial roles (transport, signal transduction, cell adhesion, etc.), compromising their functionality often leads to diseases including cancers, diabetes mellitus or cystic fibrosis. Here, we report a suite of sequence-based computational methods "Pred-MutHTP" for discriminating between disease-causing and neutral alterations in their sequence. With a data set of 11,846 disease-causing and 9,533 neutral mutations, we obtained an accuracy of 74% and 78% with 10-fold group-wise cross-validation and test set, respectively. The features used in the models include evolutionary information, physiochemical properties, neighboring residue information, and specialized membrane protein attributes incorporating the number of transmembrane segments, substitution matrices specific to membrane proteins as well as residue distributions occurring in specific topological regions. Across 11 disease classes, the method achieved accuracies in the range of 75-85%. The model designed specifically for the transmembrane segments achieved an accuracy of 85% on the test set with a sensitivity and specificity of 86% and 83%, respectively. This renders our method the current state-of-the-art with regard to predicting the effects of variants in the transmembrane protein segments. Pred-MutHTP allows predicting the effect of any variant occurring in a membrane protein-available at https://www.iitm.ac.in/bioinfo/PredMutHTP/.

Combinatorial Effects of 5-Fluorouracil and Menadione on Wnt/ß-Catenin Pathway in Human Colorectal Cancer Cells.

The incidence and mortality rates of colorectal cancer (CRC) are alarmingly high, and the scientific community is consistently engaged in developing newer therapeutic options for cancer cure or prevention. The fluoropyrimidine drug, 5-fluorouracil (5FU), remains the first line of treatment against CRC; nevertheless, relapses frequently occur since the cells gain resistance over time through various mechanisms. Studies have highlighted the significance of combinatorial treatment of a Wnt signaling inhibitor and 5FU as a better treatment strategy to overcome 5FU resistance. Small molecules that specifically target and disrupt ß-catenin-TCF interaction, a crucial step of the Wnt signaling, are promising in CRC treatment. In this study, we investigated the synergistic cytotoxic activity of menadione with 5FU as the former has previously been shown to downregulate Wnt signaling in CRC cells. Docking and experimental results suggest that the drug combination interfered with key protein-protein interactions in the ß-catenin-TCF complex, exerted synergistic anti-cancerous effects in CRC cells, and downregulated the expression of Wnt signaling proteins. Taken together, our data suggest that the simultaneous binding of 5FU and menadione to ß-catenin can block Wnt signaling by disrupting ß-catenin-TCF interaction and inhibit the proliferation of CRC cells.

Schottky Junction-Driven Photocatalytic Effect in Boron-Doped Diamond-Graphene Core-Shell Nanoarchitectures: An sp3/sp2 Framework for Environmental Remediation.

Self-formation of boron-doped diamond (BDD)-multilayer graphene (MLG) core-shell nanowalls (BDGNWs) via microwave plasma-enhanced chemical vapor deposition is systematically investigated. Here, the incorporation of nitrogen brings out the origin of MLG shells encapsulating the diamond core, resulting in unique sp3/sp2 hybridized frameworks. The evolution mechanism of the nanowall-like morphology with the BDD-MLG core-shell composition is elucidated through a variety of spectroscopic studies. The photocatalytic performance of these core-shell nanowalls is examined by the deterioration of methylene blue (MB) and rhodamine B (RhB) dyes beneath low-power ultraviolet (UV) light irradiation. Starting with 5 ppm dye solutions and employing BDGNWs as the photocatalyst, remarkable degradation efficiencies of 95% for MB within 100 min and 91% for RhB within 220 min are achieved. The effect of varying dye concentrations was also examined. The enhanced photocatalytic activity is driven by carrier photogeneration and mediated by the Schottky junction formed between BDD and MLG, promoting efficient photoinduced charge separation. The stability of the BDGNW photocatalyst is examined, and after five test runs, the photocatalytic behavior for MB and RhB degradation decreases to 87 and 85%, respectively, from initial values of 96 and 91%, demonstrating excellent photostability. These findings underscore the significance of diamond-graphene nanoarchitectures as promising green carbonaceous photocatalysts.

A Metal-Free Triazacoronene-Based Bimodal VOC Sensor.

Developing suitable sensors for selective and sensitive detection of volatile organic compounds (VOCs) is crucial for monitoring indoor and outdoor air quality. VOCs are very harmful to our health upon inhalation or contact. Bimodal sensor materials with more than one transduction capability (optical and electrical) offer the ability to extract complementary information from the individual analyte, thus improving detection accuracy and performance. The privilege of manipulating the optoelectronic properties of the polycyclic aromatic hydrocarbon-based semiconducting materials offers rapid signal transduction in multimodal sensing applications. A thiophene-functionalized triazacoronene (TTAC) donor-acceptor-donor (D-A-D) type sensor is reported here for VOC sensing. The single-crystal X-ray structure analysis of the TTAC revealed that a distinctive supramolecular polymer architecture was formed because of cooperative π-π and intermolecular D-A interactions and exhibited rapid signal transduction upon exposure to specific VOCs. The TTAC-embedded green luminescent paper-based test strip exhibited an on-off fluorescence response upon nitrobenzene vapor exposure for 120 s. The selective and rapid response is due to the fast photoinduced electron transfer, as is evident from the time-resolved excited-state dynamics and density functional theory studies. The thick-film-based prototype chemiresistive sensor detects harmful VOCs in a custom-made gas sensing system including benzene, toluene, and nitrobenzene. The TTAC sensor rapidly responds (200 s) at relatively low temperatures (180 οC) compared to other reported metal-oxide-based sensors.

Ex vivo nanofiber expansion and genetic modification of human cord blood-derived progenitor/stem cells enhances vasculogenesis.

The stem cell therapy for treating ischemic diseases is promising; however, the limited availability and compromised quality of progenitor cells in aged and diseased patients limit its therapeutic use. Here we report a nanofiber-based ex vivo stem cell expansion technology and proangiogenic growth factors overexpression of human umbilical cord blood (UCB)-derived progenitor cells to enhance angiogenic potential of therapeutic stem cells. The progenitor cells were expanded approximately 225-fold on nanofiber-based serum-free ex vivo expansion culture technique without inducing differentiation. The expanded cells express high levels of stem cell homing receptor, CXCR4, and adhesion molecule, LFA-1. The nanofiber-expanded stem cells uptake AcLDL effectively, and migrate efficiently in an in vitro transmigration assay. These expanded cells can also differentiate into endothelial and smooth muscle cells in vitro. In a NOD/SCID mouse hind limb vascular injury model, nanofiber-expanded cells were more effective in blood flow restoration and this effect was further augmented by VEGF(164) and PDGF-BB, growth factor overexpression. The data indicate that nanofiber-based ex vivo expansion technology can provide an essential number of therapeutic stem cells. Additionally, proangiogenic growth factors overexpression in progenitor cells can potentially improve autologous or allogeneic stem cell therapy for ischemic diseases.

Investigation on the early events of apoptosis in senescent erythrocytes with special emphasis on intracellular free calcium and loss of phospholipid asymmetry in chronic renal failure.

BACKGROUND: The pathophysiological link between increased blood concentrations of factors responsible for the derangement and erythrocyte membrane functions in chronic renal failure (CRF) patients are not thoroughly elucidated. We studied the erythrocyte characteristics and phospholipid asymmetry loss in CRF patients with different grades of uremia and also examined the involvement of intracellular free Ca(2+) in early events of apoptosis in uremic erythrocytes. METHODS: The studied population consisted of 90, age and sex matched control subjects (Group I) and 238 CRF cases divided into 3 groups (Group II, III and IV) according to urea concentrations and complexity of secondary complications. Erythrocyte membrane fluidity determined by binding of MC540. Intracellular free Ca(2+) concentration was determined by the 2-wavelength method by using fluorescent calcium-sensitive probe FURA-2AM. Measurement of erythrocyte phosphatidylserine exposure by flow cytometry using Annexin V-FITC. RESULTS: Cholesterol shedding increased with increasing severity of uremic complications. Erythrocytes from Group II show mild echinocyte or formation of spicules on the erythrocyte membrane surface whereas in Group III and IV they were echinocytic. Binding of MC540 was significantly higher with progression of uremic complications. Surface charge of uremic erythrocyte membrane was significantly reduced when compared with control subjects. Intracellular free Ca(2+) was positively correlated with binding of MC540 and surface hydrophobicity. The phosphatidylserine exposure of erythrocytes was significantly higher (p<0.001) in uremic patients when compared with controls. CONCLUSIONS: Phosphatidylserine (PS) exposure erythrocytes were significantly increased in uremic patients when compared with controls. Uremic complications predisposes to membrane damages in erythrocytes.

ZnO/TiO2 composites for photocatalytic inactivation of Escherichia coli.

ZnO/TiO2 composite was synthesized from zinc nitrate and anatase TiO2 by using the incipient wet impregnation method followed by calcination at 350°C for 3h. These samples were characterized through several characterization techniques. XRD peaks confirms the presence of single anatase phase of titania in the 3 and 6wt% ZnO/TiO2 composite, whereas in all other composites both anatase titania and zinc oxide phases were found. UV-visible (diffuse) reflectance spectra show titania and ZnO absorbs in the ultraviolet (UV) region whereas ZnO/TiO2 absorbs both UV and visible light. The shift in absorbance facilitates ZnO/TiO2 composites to exhibit photocatalytic activity under UV-visible light irradiation. FE-SEM and TEM analysis reveals that the particle size of ZnO is around 0.2µm and its size significantly reduced to 25nm when it is deposited on TiO2 support. The E. coli inactivation study shows that ZnO/TiO2 composites exhibit high inactivation compared to ZnO and titania under UV alone and the combination of both UV-visible. With the increasing loading concentration of ZnO, the photocatalytic inactivation potential of ZnO/TiO2 composites also increases. The E. coli inactivation of ZnO/TiO2 is explained based on the photocatalytically generated ROS, ZnO dissolution and charge carrier separation due to hybrid structures.

Importance of functional groups in predicting the activity of small molecule inhibitors for Bcl-2 and Bcl-xL.

Evasion of apoptosis owing to aberrant expression of Bcl-2 (B-cell lymphoma-2) anti-apoptotic proteins is a promising hallmark of cancer. These proteins are associated with resistance to chemotherapy and radiation. Currently available QSAR models are limited to a set of inhibitors corresponding to a particular chemical scaffold, and unified models are required to identify the differential specificity of diverse compounds toward inhibiting these targets. In this study, we predicted the factors driving differential activity and specificity implementing multiplexed QSAR analysis for a dataset of 1,649 reported inhibitors of Bcl-2 (B-cell lymphoma-2) and Bcl-xL (B-cell lymphoma-extra large). We developed QSAR models for seven diverse scaffolds and critically analyzed the chemical space with coupling factors. The correlation values of QSAR models for Bcl-2 and Bcl-xL range from 0.95 to 0.985. The MAE and sMAPE of the models were in the range of 0.052-5.4 nm and 0.41%-10%, respectively, signifying model robustness. The crucial descriptors and moieties accounting for the activity were benchmarked against experimentally determined binding patterns. The comprehensive analysis made in the study explores latent features of the chemical space in a broad perspective. Further, we have developed a user-friendly Web server for predicting a specific/dual inhibitor of Bcl-2 and Bcl-xL [http://www.iitm.ac.in/bioinfo/APPLE/].

A biphasic effect of TNF-α in regulation of the Keap1/Nrf2 pathway in cardiomyocytes.

Antagonizing TNF-α signaling attenuates chronic inflammatory disease, but is associated with adverse effects on the cardiovascular system. Therefore the impact of TNF-α on basal control of redox signaling events needs to be understand in more depth. This is particularly important for the Keap1/Nrf2 pathway in the heart and in the present study we hypothesized that inhibition of a low level of TNF-α signaling attenuates the TNF-α dependent activation of this cytoprotective pathway. HL-1 cardiomyocytes and TNF receptor1/2 (TNFR1/2) double knockout mice (DKO) were used as experimental models. TNF-α (2-5ng/ml, for 2h) evoked significant nuclear translocation of Nrf2 with increased DNA/promoter binding and transactivation of Nrf2 targets. Additionally, this was associated with a 1.5 fold increase in intracellular glutathione (GSH). Higher concentrations of TNF-α (>10-50ng/ml) were markedly suppressive of the Keap1/Nrf2 response and associated with cardiomyocyte death marked by an increase in cleavage of caspase-3 and PARP. In vivo experiments with TNFR1/2-DKO demonstrates that the expression of Nrf2-regulated proteins (NQO1, HO-1, G6PD) were significantly downregulated in hearts of the DKO when compared to WT mice indicating a weakened antioxidant system under basal conditions. Overall, these results indicate that TNF-α exposure has a bimodal effect on the Keap1/Nrf2 system and while an intense inflammatory activation suppresses expression of antioxidant proteins a low level appears to be protective.

Credentials of Spirulina diet on stability and flux related properties on the biomineralization process during oxalate mediated renal calcification in rats.

BACKGROUND: High Spirulina diet is a potential risk factor for nephrolithiasis since it has the capacity to increase urinary oxalate and uric acid level, facilitating lithogenesis. Our aim was to identify the effect of Spirulina diet during hyperoxaluric condition in Wistar albino rats. METHODS: The animals were divided into four groups: control (Gl, n=6); ethylene glycol (EG) induced (G2, n=6); EG+Spirulina (G3, n=6); Spirulina alone (G4, n=6). EG at 0.75% was administered to G2 and G3 through drinking water for 4 weeks and Spirulina 1500 mg/kg feed was administered to G3 and G4. RESULTS: Urinary parameters like oxalate, uric acid, calcium, urea, and creatinine (P<0.001) were found increased after Spirulina diet under hyperoxaluric conditions compared to the same without Spirulina diet. Similarly the BUN, plasma contents of uric acid, urea, creatinine (P<0.001) were found to be raised in G3. The renal and RBC GSH levels, as estimated by HPLC, seemed decreased when compared to G2. CONCLUSIONS: The present study shows that free radicals aid in the progression of nephrolithiasis. The crystal deposition was found to be high in the renal cells of G3 than G2 and TEM revealed damage in renal cell of G3 implying that the disease deteriorates by free radical injury. In contrast the Spirulina diet alone (G4) did not induce any features relating to stone forming condition suggesting that free radical release might have been suppressed due to enrichment of dietary antioxidants and vitamins. Thus the present investigation demonstrates that during hyperoxaluric conditions the Spirulina diet must possibly be avoided and can be considered in normal subjects checked for family history of renal stone deposition.

Salubrious effect of C-phycocyanin against oxalate-mediated renal cell injury.

BACKGROUND: C-phycocyanin, a biliprotein pigment found in some blue green algae (Spirulina platensis) with nutritional and medicinal properties, was investigated for its efficacy on sodium oxalate-induced nephrotoxicity in experimentally induced urolithic rats. METHODS: Male Wistar rats were divided into four groups. Hyperoxaluria was induced in two of these groups by intraperitoneal infusion of sodium oxalate (70 mg/kg), and a pretreatment of phycocyanin (100 mg/kg) as a single oral dosage was given to one of these groups by 1 h prior to sodium oxalate infusion challenges. The study also encompasses an untreated control group and a phycocyanin-alone treated drug control group. The extent of lipid peroxidation (LPO) was evaluated in terms of renal concentrations of MDA, conjugated diene and hydroperoxides. The following assay was performed in the renal tissue (a) antioxidant enzymes such as superoxide dismutase (SOD) and catalase, (b) glutathione metabolizing enzymes such as glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) and glucose 6-phosphate dehydrogenase (G6PD), (c) the low molecular weight antioxidants (GSH, vitamins E and C) and protein carbonyl content. RESULTS: The increased concentrations of MDA, conjugated diene and hydroperoxide (index of the lipid peroxidation) were controlled (P < 0.001) in the phycocyanin-pretreated group. At the outset, the low molecular weight antioxidants were appreciably increased (P < 0.001), whereas the tissue protein carbonyl concentration was decreased (P < 0.001), suggesting that phycocyanin provides protection to renal cell antioxidants. It was noticed that the activities of antioxidant enzymes and glutathione metabolizing enzymes were considerably stabilized in rats pretreated with phycocyanin. CONCLUSION: We suggest that phycocyanin protects the integrity of the renal cell by stabilizing the free radical mediated LPO and protein carbonyl, as well as low molecular weight antioxidants and antioxidant enzymes in renal cells. Thus, the present analysis reveals that the antioxidant nature of C-phycocyanin protects the renal cell against oxalate-induced injury and may be a nephroprotective agent.

Prophylactic role of phycocyanin: a study of oxalate mediated renal cell injury.

Oxalate induced renal calculi formation and the associated renal injury is thought to be caused by free radical mediated mechanisms. An in vivo model was used to investigate the effect of phycocyanin (from Spirulina platensis), a known antioxidant, against calcium oxalate urolithiasis. Male Wistar rats were divided into four groups. Hyperoxaluria was induced in two of these groups by intraperitoneal infusion of sodium oxalate (70 mg/kg) and a pretreatment of phycocyanin (100 mg/kg) as a single oral dosage was given, 1h prior to sodium oxalate infusion. An untreated control and drug control (phycocyanin alone) were also included in the study. We observed that phycocyanin significantly controlled the early biochemical changes in calcium oxalate stone formation. The antiurolithic nature of the drug was evaluated by the assessment of urinary risk factors and light microscopic observation of urinary crystals. Renal tubular damage as divulged by urinary marker enzymes (alkaline phosphatase, acid phosphatase and gamma-glutamyl transferase) and histopathological observations such as decreased tubulointerstitial, tubular dilatation and mononuclear inflammatory cells, indicated that renal damage was minimised in drug-pretreated group. Oxalate levels (P < 0.001) and lipid peroxidation (P < 0.001) in kidney tissue were significantly controlled by drug pretreatment, suggesting the ability of phycocyanin to quench the free radicals, thereby preventing the lipid peroxidation mediated tissue damage and oxalate entry. This accounts for the prevention of CaOx stones. Thus, the present analysis revealed the antioxidant and antiurolithic potential of phycocyanin thereby projecting it as a promising therapeutic agent against renal cell injury associated kidney stone formation.

Water disinfection through photoactive modified titania.

TiO(2), N-TiO(2) and S-TiO(2) samples have been prepared by various chemical methods. These samples were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Laser Raman spectrometer, UV-Visible spectrophotometer, field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). X-ray powder diffraction study reveals that all three samples are single anatase phase of titania and the crystallinity of titania decreases with sulphur doping whereas nitrogen doping does not affect it. UV-Visible (diffuse) reflectance spectra shows that doping of titania with nitrogen and sulphur shift the absorption edge of titania from ultraviolet to visible region. XPS study confirms that both nitrogen and sulphur are well doped in the titania lattice. It is observed that nitrogen occupies at both substitutional and interstitial position in the lattice of titania. FE-SEM and TEM studies demonstrate that the particles are below 50nm range. It is found that S and N doping of titania increased its water disinfection property in the order TiO(2)

N-substituted 1,2-dihydroquinolines as anticancer agents: electronic control of redox stability, assessment of antiproliferative effects, and mechanistic insights.

Redox chemotherapy: Antiproliferative activities of a series of N-substituted 1,2-dihydroquinolines capable of causing redox imbalance in cancer cells are presented. Detailed studies showed that these derivatives arrest the cell cycle in the G2/M phase and induce apoptosis through an intrinsic pathway characterized by loss of mitochondrial membrane potential, DNA fragmentation, cytochrome c release, and activation of caspases 9 and 3.

Nimbolide, a neem limonoid abrogates canonical NF-κB and Wnt signaling to induce caspase-dependent apoptosis in human hepatocarcinoma (HepG2) cells.

Nuclear factor kappa B (NF-κB), an oncogenic signaling factor plays a critical role in the development and progression of various cancers. The objective of this study was to investigate the effect of nimbolide, a neem derived tetranortriterpenoid on NF-κB signaling and its downstream events - Wnt/ß-catenin activation and apoptosis evasion in human hepatocarcinoma (HepG2) cells by evaluating NF-κB family members (NF-κB-p50, p65, IκB-α, p-IκB-α, and IKKß), members of Wnt signaling (GSK-3ß and ß-catenin), and intrinsic apoptosis (Bcl-2, Bax, cytochrome c, Smac/DIABLO, caspase-3, and caspase-9). Our results demonstrate that nimbolide concurrently abrogates canonical NF-κB and Wnt signaling and induces intrinsic apoptosis in HepG2 cells. These data suggest that phytochemicals such as nimbolide that can target multiple steps along the NF-κB signaling circuit are promising candidates for future phytochemical-based mechanistic pathway targeted anticancer regimens.

Stem cell therapy with overexpressed VEGF and PDGF genes improves cardiac function in a rat infarct model.

BACKGROUND: Therapeutic potential was evaluated in a rat model of myocardial infarction using nanofiber-expanded human cord blood derived hematopoietic stem cells (CD133+/CD34+) genetically modified with VEGF plus PDGF genes (VIP). METHODS AND FINDINGS: Myocardial function was monitored every two weeks up to six weeks after therapy. Echocardiography revealed time dependent improvement of left ventricular function evaluated by M-mode, fractional shortening, anterior wall tissue velocity, wall motion score index, strain and strain rate in animals treated with VEGF plus PDGF overexpressed stem cells (VIP) compared to nanofiber expanded cells (Exp), freshly isolated cells (FCB) or media control (Media). Improvement observed was as follows: VIP>Exp> FCB>media. Similar trend was noticed in the exercise capacity of rats on a treadmill. These findings correlated with significantly increased neovascularization in ischemic tissue and markedly reduced infarct area in animals in the VIP group. Stem cells in addition to their usual homing sites such as lung, spleen, bone marrow and liver, also migrated to sites of myocardial ischemia. The improvement of cardiac function correlated with expression of heart tissue connexin 43, a gap junctional protein, and heart tissue angiogenesis related protein molecules like VEGF, pNOS3, NOS2 and GSK3. There was no evidence of upregulation in the molecules of oncogenic potential in genetically modified or other stem cell therapy groups. CONCLUSION: Regenerative therapy using nanofiber-expanded hematopoietic stem cells with overexpression of VEGF and PDGF has a favorable impact on the improvement of rat myocardial function accompanied by upregulation of tissue connexin 43 and pro-angiogenic molecules after infarction.

Oxalate mediated nephronal impairment and its inhibition by c-phycocyanin: a study on urolithic rats.

The assumption of oxidative stress as a mechanism in oxalate induced renal damage suggests that antioxidants might play a beneficial role against oxalate toxicity. An in vivo model was used to investigate the effect of C-phycocyanin (from aquatic micro algae; Spirulina spp.), a known antioxidant, against calcium oxalate urolithiasis. Hyperoxaluria was induced in two of the 4 groups of Wistar albino rats (n = 6 in each) by intraperitoneally injecting sodium oxalate (70 mg/kg body weight). A pretreatment of phycocyanin (100 mg/kg body weight) as a single oral dosage was given, one hour prior to oxalate challenge. An untreated control and drug control (phycocyanin alone) were employed. Phycocyanin administration resulted in a significant improvement (p < 0.001) in the thiol content of renal tissue and RBC lysate via increasing glutathione and reducing malondialdehyde levels in the plasma of oxalate induced rats (p < 0.001), indicating phycocyanin's antioxidant effect on oxalate mediated oxidative stress. Administering phycocyanin after oxalate treatment significantly increased catalase and glucose-6-phosphate dehydrogenase activity (p < 0.001) in RBC lysate suggesting phycocyanin as a free radical quencher. Assessing calcium oxalate crystal retention in renal tissue using polarization microscopy and renal ultrastructure by electron microscopy reveals normal features in phycocyanin-- pretreated groups. Thus the study presents positive pharmacological implications of phycocyanin against oxalate mediated nephronal impairment and warrants further work to tap this potential aquatic resource for its medicinal application.

Alterations in band 3 protein and anion exchange in red blood cells of renal failure patients.

The precise nature of band 3 protein and its involvement in oxalate exchange in the red blood cells (RBCs) of renal failure patients has not been studied in detail. Therefore, here we studied the oxalate exchange and binding by band 3 protein in RBCs of humans with conditions of acute and chronic renal failure (ARF and CRF). The RBCs of ARF and CRF patients exhibited abnormal red cell morphology and an increased resistance to osmotic hemolysis. Further, an increase in the cholesterol content and decrease in the activities of Na(+)-K(+)-, Ca(2+)-, and Mg(2+)-ATPases of membranes were observed in the RBCs of ARF and CRF patients. A decrease in the oxalate flux was observed in the RBCs of ARF and CRF patients. The oxalate-binding activities of the RBC membranes were significantly lower in ARF (20 pmoles/mg protein) and CRF (5.3 pmoles/mg protein) patients as compared to that in the normal subjects (36 pmoles/mg protein). DEAE-cellulose and Sephadex G-200 column chromatography purification profiles revealed a distinctive shift in oxalate-binding activity of band 3 protein of RBCs of ARF and CRF patients as compared to that of the normal subjects. It was also observed from the binding studies with a fluorescent dye, eosin-5-maleimide, which specifically binds to band 3 protein, that the RBCs of ARF and CRF patients exhibited only 53 and 32% of abundance of band 3 protein, respectively, as compared to that in the RBCs of the normal subjects, thus revealing a decrease in the band 3 protein content in ARF and CRF patients. These results for the first time showed a decrease in the oxalate exchange in RBCs of patients with ARF and CRF, which was also concomitant with the low levels of abundance of band 3 protein.

Detection of endothelial nitric oxide synthase and NADPH-diaphorase in experimentally induced hyperoxaluric animals.

Nitrosative stress plays a role in calcium oxalate stone formation, as nitrosated proteins have been identified in stone formers. Nitric oxide (NO(*)), the common precursor for reactive nitrogen species, is synthesized in the juxtaglomerular apparatus of the kidneys. The present study is aimed to determine the role of nitric oxide synthase (NOS) in an experimental hyperoxaluric condition by histological and biochemical techniques. Hyperoxaluria was induced by 0.75% ethylene glycol in drinking water. L-arginine (L-arg) was supplemented at a dose of 1.25 g/kg body weight orally for 28 days. Nitric oxide metabolites (NOx), protein content in the urine and lipid peroxidation in the kidney were determined at the end of the experimental period. Histopathological examination of the rat kidneys was then carried out. NADPH-diaphorase and eNOS expression studies were carried out in control and hyperoxaluric rat kidneys using histochemical and immunohistochemical techniques. Significant amounts of NOx were present in the urine of hyperoxaluric animals when compared to control rats. Histopathological examinations revealed membrane injury, tubular dilatation and edema in the hyperoxaluric rats, whereas co-supplementation of L-arg to the hyperoxaluric rats significantly reduced these changes. The results of histochemical analysis for NADPH-diaphorase staining demonstrate the role of NOS in hyperoxaluric rats. Hyperoxaluric rats showed intense staining for NADPH-diaphorase when compared to control and L-arg co-supplemented hyperoxaluric rats. Immunohistochemical demonstration confirmed that eNOS expression was markedly increased in L-arg supplemented rats, when compared to EG treated rat kidney sections. Thus, from the present study, we conclude that supplementation of L-arg to the hyperoxaluric animals minimizes the cellular injury mediated by ethylene glycol, prevents oxidative/nitrosative damage to the membranes and reduces the incidence of calcium oxalate stone formation.