Cobalt electrodeposition onto highly oriented pyrolytic graphite (HOPG) electrode from ammonium sulfate solutions

It was carried out an electrochemical study of the cobalt electrodeposition onto HOPG electrode from an aqueous solution containing 10-2 M of CoSO4 + 1M (NH4)2SO4. Nucleation parameters such as nucleation rate, density of active nucleation sites, saturation nucleus and the rate constant of the proton reduction reaction (kPR) were determined from potentiostatic studies. An increase in kPR values with the decrease in the applied potential suggested a competition between H+ and Co2+ by the active sites on the surface. The ΔG energy calculated for the formation of stable nucleus was 8.21x10-21 J/nuclei. The AFM study indicated the formation of small clusters of 50-400 nm in diameter and 2-120 nm in height.

Spectrophotometric method for determination of atazanavir sulfate in capsule dosage form

Two sensitive and simple spectrophotmetric methods were developed for determination of Atazanavir Sulfate in capsule dosage form. The first method was based on the oxidative coupling of ATV with 3-Methyl Benzothiazolin-2-one hydrazone (MBTH). The resulting green product had Λmax of 627.3 nm and was stable for 2 h. The second method was based on the reaction between diazotized drug with N-(1-napthyl)ethylenediamine dihydrochloride (NEDA) in neutral medium to yield yellowish orange product which had Λmax of 517.1 nm. The product was stable for 4 h. Both methods were highly reproducible and had been applied to pharmaceutical preparations.

Construction and application of a portable microcontrolled turbidimeter for the in situ determination of sulfate

This study reports on the construction of a turbidimeter employing light emitting diodes as radiation source at a wavelength of 405 nm, a photodiode as detector, a temperature sensor and a microcontroller used for data acquisition and processing. The turbidimeter was applied to determine sulfate concentrations in natural water employing barium chloride as reagent. Potential interferences and recovery studies were performed and an interference of 3.5 % and a recovery between 97.8 and 108 % were estimated. The analytical performance of in situ turbidimeter for the determination of sulfate was evaluated and compared with two commercial spectrophotometers and a good agreement was obtained.

Sodium dodecyl sulfate coated γ-alumina support modified by a new Schiff base for solid phase extraction and flame-AAS determination of lead and copper ions

A simple and fast approach for solid phase extraction is herein described, and used to determine trace amounts of Pb2+ and Cu2+ metal ions. The solid phase support is sodium dodecyl sulfate (SDS)-coated γ-alumina modified with bis(2-hydroxy acetophenone)-1,6-hexanediimine (BHAH) ligand. The adsorbed ions were stripped from the solid phase by 6 mL of 4 M nitric acid as eluent. The eluting solution was analyzed by flame atomic absorption spectrometry (FAAS). The sorption recovery of metal ions was investigated with regard to the effects of pH, amount of ligand, γ-alumina and surfactant and the amount and type of eluent. Complexation of BHAH with Pb2+ or Cu2+ ions was examined via spectrophotometry using the HypSpec program. The detection limit for Cu2+ was 7.9 µg L-1 with a relative standard deviation of 1.67%, while that for Pb2+ was 6.4 µg L-1 with a relative standard deviation of 1.64%. A preconcentration factor of 100 was achieved for these ions. The method was successfully applied to determine analyte concentrations in samples of liver, parsley, cabbage, and water.

Determination of sulfate in the wet-process of phosphoric acid by reverse flow injection

An improved method based on reverse flow injection is proposed for determining sulfate concentration in the wet-process of phosphoric acid (WPA). The effect of reagent composition, flow rate, temperature, acid concentration, length of the reaction coil, and linear response range on the flow system is discussed in detail. Optimal conditions are established for determining sulfate in the WPA samples. Baseline drift is avoided by a periodic washing step with EDTA in an alkaline medium. A linear response is observed within a range of 20 - 360 mg L-1, given by the equation A = 0.0020C (mg L-1) + 0.0300, R² = 0.9991. The detection limit of the proposed method for sulfate analysis is 3 mg L-1, and the relative standard deviation (n = 12) of sulfate absorbance peak is less than 1.60%. This method has a rate of up to 29 samples per hour, and the results compare well with those obtained with gravimetric method.

Gray mold severity and vase life of rose buds after pulsing with citric acid, salicylic acid, calcium sulfate, sucrose and silver thiosulfate

Gray mold of roses (Rosa hibrida) caused by Botrytis cinerea requires many management strategies for its control. The effect of pulsing rose cv. Kiss with solutions of citric acid, salicylic acid, sucrose, calcium sulfate, and silver thiosulfate (STS) on disease severity and vase life of the flowers was evaluated. The solutions were applied to cut stems at different stages of harvest, the variation in the opening stage of harvest did not affect the results. Pulsing with STS reduced the values of area under the disease progress curve (AUDPC) and of severity of disease by 15% and 55%, respectively, and increased the vase life of the flowers by 20%. Calcium sulfate consistently reduced AUDPC by 66% and maximum severity by 88%, and increased vase life of the flowers by 37%. Therefore, pulsing rose buds with solutions of STS and calcium sulfate is potentially useful in reducing losses due to gray mold after harvest and in extending the vase life.

Heparan sulfate and cell division

Heparan sulfate is a component of vertebrate and invertebrate tissues which appears during the cytodifferentiation stage of embryonic development. Its structure varies according to the tissue and species of origin and is modified during neoplastic transformation. Several lines of experimental evidence suggest that heparan sulfate plays a role in cellular recognition, cellular adhesion and growth control. Heparan sulfate can participate in the process of cell division in two distinct ways, either as a positive or negative modulator of cellular proliferation, or as a response to a mitogenic stimulus.

Effects of aluminum sulfate on delta-aminolevulinate dehydratase from kidney, brain, and liver of adult mice

The purpose of the present study was to investigate the in vitro and in vivo effects of aluminum sulfate on delta-aminolevulinic acid dehydratase (ALA-D) activity from the brain, liver and kidney of adult mice (Swiss albine). In vitro experiments showed that the aluminum sulfate concentration needed to inhibit the enzyme activity was 1.0-5.0 mM (N = 3) in brain, 4.0-5.0 mM (N = 3) in liver and 0.0-5.0 mM (N = 3) in kidney. The in vivo experiments were performed on three groups for one month: 1) control animals (N = 8); 2) animals treated with 1 g% (34 mM) sodium citrate (N = 8) and 3) animals treated with 1 g% (34 mM) sodium citrate plus 3.3 g% (49.5 mM) aluminum sulfate (N = 8). Exposure to aluminum sulfate in drinking water inhibited ALA-D activity in kidney (23.3 ± 3.7%, mean ± SEM, P<0.05 compared to control), but enhanced it in liver (31.2 ± 15.0%, mean ± SEM, P<0.05). The concentrations of aluminum in the brain, liver and kidney of adult mice were determined by graphite furnace atomic absorption spectrometry. The aluminum concentrations increased significantly in the liver (527 ± 3.9%, mean ± SEM, P<0.05) and kidney (283 ± 1.7%, mean ± SEM, P<0.05) but did not change in the brain of aluminum-exposed mice. One of the most important and striking observations was the increase in hepatic aluminum concentration in the mice treated only with 1 g% sodium citrate (34 mM) (217 ± 1.5%, mean ± SEM, P<0.05 compared to control). These results show that aluminum interferes with delta-aminolevulinate dehydratase activity in vitro and in vivo. The accumulation of this element was in the order: liver > kidney > brain. Furthermore, aluminum had only inhibitory properties in vitro, while in vivo it inhibited or stimulated the enzyme depending on the organ studied.

Anxiolytic-like effects of 4-phenyl-2-trichloromethyl-3H-1,5-benzodiazepine hydrogen sulfate in mice

The pharmacological effects of 4-phenyl-2-trichloromethyl-3H-1,5-benzodiazepine hydrogen sulfate (PTMB), a novel synthetic benzodiazepine, were examined in mice. In the elevated plus-maze test of anxiety, 0.3-1 mg/kg diazepam ip (F(3,53) = 3.78; P<0.05) and 1-10 mg/kg PTMB ip increased (F(5,98) = 3.26; P<0.01), whereas 2 mg/kg picrotoxin ip decreased (F(3,59) = 8.32; P<0.001) the proportion of time spent in the open arms, consistent with an anxiolytic action of both benzodiazepines, and an anxiogenic role for picrotoxin. In the holeboard, 1.0 mg/kg diazepam ip increased (F(3,54) = 2.78; P<0.05) and 2 mg/kg picrotoxin ip decreased (F(3,59) = 4.69; P<0.01) locomotor activity. Rotarod assessment revealed that 1 mg/kg diazepam ip and 3, 10 and 30 mg/kg PTMB ip produced significant motor incoordination compared to vehicle control (F(4,70) = 7.6; P<0.001). These data suggest that the recently synthesized PTMB compound possesses anxiolytic activity and produces motor incoordination similar to those observed with diazepam.

Heparan sulfate and control of cell division: adhesion and proliferation of mutant CHO-745 cells lacking xylosyl transferase

We have examined the role of cell surface glycosaminoglycans in cell division: adhesion and proliferation of Chinese hamster ovary (CHO) cells. We used both wild-type (CHO-K1) cells and a mutant (CHO-745) which is deficient in the synthesis of proteoglycans due to lack of activity of xylosyl transferase. Using different amounts of wild-type and mutant cells, little adhesion was observed in the presence of laminin and type I collagen. However, when fibronectin or vitronectin was used as substrate, there was an enhancement in the adhesion of wild-type and mutant cells. Only CHO-K1 cells showed a time-dependent adhesion on type IV collagen. These results suggest that the two cell lines present different adhesive profiles. Several lines of experimental evidence suggest that heparan sulfate proteoglycans play a role in cell adhesion as positive modulators of cell proliferation and as key participants in the process of cell division. Proliferation and cell cycle assays clearly demonstrate that a decrease in the amount of glycosaminoglycans does not inhibit the proliferation of mutant CHO-745 cells when compared to the wild type CHO-K1, in agreement with the findings that both CHO-K1 and CHO-745 cells take 8 h to enter the S phase.

Glycosaminoglycans affect the interaction of human plasma kallikrein with plasminogen, factor XII and inhibitors

Human plasma kallikrein, a serine proteinase, plays a key role in intrinsic blood clotting, in the kallikrein-kinin system, and in fibrinolysis. The proteolytic enzymes involved in these processes are usually controlled by specific inhibitors and may be influenced by several factors including glycosaminoglycans, as recently demonstrated by our group. The aim of the present study was to investigate the effect of glycosaminoglycans (30 to 250 µg/ml) on kallikrein activity on plasminogen and factor XII and on the inhibition of kallikrein by the plasma proteins C1-inhibitor and antithrombin. Almost all available glycosaminoglycans (heparin, heparan sulfate, bovine and tuna dermatan sulfate, chondroitin 4- and 6-sulfates) reduced (1.2 to 3.0 times) the catalytic efficiency of kallikrein (in a nanomolar range) on the hydrolysis of plasminogen (0.3 to 1.8 µM) and increased (1.9 to 7.7 times) the enzyme efficiency in factor XII (0.1 to 10 µM) activation. On the other hand, heparin, heparan sulfate, and bovine and tuna dermatan sulfate improved (1.2 to 3.4 times) kallikrein inhibition by antithrombin (1.4 µM), while chondroitin 4- and 6-sulfates reduced it (1.3 times). Heparin and heparan sulfate increased (1.4 times) the enzyme inhibition by the C1-inhibitor (150 nM).

Decorin is one of the proteoglycans expressed in Walker 256 rat mammary carcinoma

Proteoglycan and glycosaminoglycan content was analyzed in a model of rat mammary carcinoma to study the roles of these compounds in tumorigenesis. Hyaluronic acid and proteoglycans bearing chondroitin and/or dermatan sulfate chains were detected in solid tumors obtained after subcutaneous inoculation of Walker 256 rat carcinoma cells. About 10% of sulfated glycosaminoglycan chains corresponded to heparan sulfate. The small leucine-rich proteoglycan, decorin, was identified as one of the proteoglycans, in addition to others of higher molecular weight, by cross-reaction with an antiserum raised against pig laryngeal decorin and by N-terminal amino acid sequencing. Decorin was separated from other proteoglycans by hydrophobic chromatography and its complete structure was determined. It has a molecular weight of about 85 kDa and a dermatan chain of 45 kDa with 4-sulfated disaccharides. After degradation of the glycosaminoglycan chain, three core proteins of different molecular weight (36, 46 and 56 kDa) were identified. The presence of hyaluronic acid and decorin has been reported in a variety of tumors and tumor cells. In the Walker 256 mammary carcinoma model, hyaluronic acid may play an important role in tumor progression, since it provides a more hydrated extracellular matrix. On the other hand, decorin, which is expressed by stromal cells, represents a host defense response to tumor growth.

Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Quantitative evaluation of experimental choroidal neovascularization by confocal scanning laser ophthalmoscopy: fluorescein angiogram parallels heparan sulfate proteoglycan expression

The objective of the present study was to develop a quantitative method to evaluate laser-induced choroidal neovascularization (CNV) in a rat model using Heidelberg Retina Angiograph 2 (HRA2) imaging. The expression of two heparan sulfate proteoglycans (HSPG) related to inflammation and angiogenesis was also investigated. CNV lesions were induced with argon laser in 21 heterozygous Zucker rats and after three weeks a fluorescein angiogram and autofluorescence exams were performed using HRA2. The area and greatest linear dimension were measured by two observers not aware of the protocol. Bland-Altman plots showed agreement between the observers, suggesting that the technique was reproducible. After fluorescein angiogram, HSPG (perlecan and syndecan-4) were analyzed by real-time RT-PCR and immunohistochemistry. There was a significant increase in the expression of perlecan and syndecan-4 (P < 0.0001) in retinas bearing CNV lesions compared to control retinas. The expression of these two HSPG increased with increasing CNV area. Immunohistochemistry demonstrated that the rat retina damaged with laser shots presented increased expression of perlecan and syndecan-4. Moreover, we observed that the overexpression occurred in the outer layer of the retina, which is related to choroidal damage. It was possible to develop a standardized quantitative method to evaluate CNV in a rat model using HRA2. In addition, we presented data indicating that the expression of HSPG parallels the area of CNV lesion. The understanding of these events offers opportunities for studies of new therapeutic interventions targeting these HSPG.