Evaluation of the antischistosomal activity of sulfated α-D-glucan from the lichen Ramalina celastri free and encapsulated into liposomes

The antischistosomal activity of the sulfated polysaccharide α-D-glucan (Glu.SO4) extracted from Ramalina celastri was evaluated after encapsulation into liposomes (Glu.SO4-LIPO) in Schistosoma mansoni-infected mice. The effect of treatment with Glu.SO4 and Glu.SO4-LIPO (10 mg/kg) on egg elimination, worm burden and hepatic granuloma formation was assessed using female albino Swiss mice, 35-40 days of age, weighing 25 ± 2 g, infected with 150 cercariae/animal (Biomphalaria glabrata, BH strain). Four groups (N = 10) were studied, two controls (empty liposomes and NaCl) and two treated groups (Glu.SO4-LIPO and Glu.SO4) using a single dose. Parasitological analysis revealed that Glu.SO4-LIPO was as efficient as Glu.SO4 in reducing egg elimination and worm burden. Treatment with free Glu.SO4 and Glu.SO4-LIPO induced a statistically significant reduction in the number of granulomas (62 and 63 percent, respectively). Lectin histochemistry showed that wheat germ agglutinin intensely stained the egg-granuloma system in all treated groups. On the other hand, peanut agglutinin stained cells in the control groups, but not in the treated groups. The present results suggest a correlation between the decreasing number of hepatic egg-granulomas and the glycosylation profile of the egg-granuloma system in animals treated with free Glu.SO4 or Glu.SO4-LIPO.

Sulfated fucan as support for antibiotic immobilization

Xylofucoglucuronan from Spatoglossum schrõederi algae was tested as a support for antibiotic immobilization. The polysaccharide (20 mg in 6 ml) was first activated using carbodiimide, 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide methiodide (20 mg in 2 ml), under stirring for 1 h at 25ºC and pH from 4.5 to 5.0. After adjusting the pH to 8.0, either gentamicin or amikacin (62.5 mg in 1.25 ml) was then immobilized on this chemically modified polysaccharide with shaking for 24 h in a cold room. Infrared spectra of the activated carbodiimide xylofucoglucuronan showed two bands to carbonyl (C = O at 1647.9 and 1700.7 cm-1) and to amide (Cpsi-NH2) groups (1662.8 and 1714.0 cm-1). Microbial characterization of the derivatives was carried out by the disk diffusion method using Staphylococcus aureus or Klebsiella pneumoniae incorporated in Müller Hinton medium. Inhibition halos of bacterial growth were observed for the antibiotics immobilized on this sulfated heteropolysaccharide before and after dialysis. However, the halos resulting from the samples after dialysis were much smaller, suggesting that dialysis removed either non-covalently bound antibiotic or other small molecules. In contrast, bacterial growth was not inhibited by either xylofucoglucuronan or its activated form or by gentamicin or amikacin after dialysis. An additional experiment was carried out which demonstrated that the sulfated heteropolysaccharide was hydrolyzed by the microorganism. Therefore, the antibiotic immobilized on xylofucoglucuronan can be proposed as a controlled drug delivery system. Furthermore, this sulfated heteropolysaccharide can be extracted easily from sea algae Spatoglossum schrõederi.

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA

We developed an efficient method to prepare a hybrid inorganic-organic composite based on polyvinyl alcohol (PVA) and polysiloxane using the sol-gel disc technique. Antigen obtained from Yersinia pestis was covalently immobilized onto these discs with glutaraldehyde and used as solid phase in ELISA for antibody detection in serum of rabbits experimentally immunized with plague. Using 1.25 æg antigen per disc, a peroxidase conjugate dilution of 1:4,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. These values are similar to those used for PVA-glutaraldehyde discs, plasticized filter paper discs and the polyaniline-Dacron composite discs. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates, with the amount of antigen being one fourth that employed in conventional PVC plates (5 æg/well). In addition to the performance of the polysiloxane/PVA-glutaraldehyde disc as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application

The use of filter paper plasticized with polyvinyl alcohol-glutaraldehyde in ELISA

F1-antigen purified from Yersinia pestis was covalently linked to 5-mm diameter filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde. These discs were used both for ELISA and dot-ELISA for the detection of anti-F1 IgG in rabbits. The best conditions were achieved using 1.25 µg of F1 antigen/disc, 3 percent w/v skim milk in PBS as blocking agent, anti-IgG peroxidase conjugate diluted 12,000 times, and serum from rabbits immunized or not against Y. pestis, diluted 6,400 times. The absorbance values obtained from the comparative study between this procedure and conventional ELISA were not significantly different but the low cost of the reagents employed in ELISA using the filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde makes this method economically attractive.

Cellulose acetate as solid phase in ELISA for plague

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 µg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.

Fator atrial natriurético: uma revisão direcionada / Factor atrial

Estudou-se o fator atrial natriurético (FAN), analisando-se a sua estrutura bioquímica, a fisiologia e a sua interação em situações de adaptação fisiológica, nas cardiopatias e em outras doenças. Foi feita uma revisão dos métodos de diagnóstico e o seu valor, como elemento preditivo de gravidade das doenças. Especulou-se sobre a sua potencial aplicabilidade na prática clínica e utilidade terapêutica

Immobilization of xanthine oxidase on a polyaniline silicone support

A polyaniline silicone support to immobilize xanthine oxidase is proposed as a reactor coil to monitor the action of xanthine oxidase on hypoxanthine, xanthine and 6-mercaptopurine. A purified xanthine oxidase immobilized on this support lost 80 per cent of the initial activity after 12 min of use. Co-immobilization of superoxide dismutase and catalase increased the stability of immobilized xanthine oxidase so that the derivative maintained 79 per cent of its initial activity after 4.6 h of continuous use in which 1.5 mumol purine bases were converted by the immobilized enzyme system. There is no evidence of either polyaniline or protein leaching from the coil during 3 h of continuous use. When solutions (10 ml) of hypoxanthine, xanthine and 6-mercaptopurine were circulated individually through the xanthine oxidase-superoxide dismutase-catalase-polyaniline coil (1 mm internal diameter and 3 m in length, 3 ml internal volume) activities of 8.12, 11.17 and 1.09 nmol min-1 coil-1, respectively, were obtained. The advantages of the reactor configuration and the redox properties of the polymer, particularly with respect to immobilized oxidoreductases, make this methodology attractive for similar enzyme systems. This immobilized enzyme system using polyaniline-silicone as support converted 6-mercaptopurine to 6-thiouric acid with equal efficiency as resins based on polyacrylamide and polyamide 11.

Action of immobilized xanthine oxidase on purines

Xanthine oxidase was covalently immbolized on polyacrylamide gel beads, polyamide- 11 and dacron. Hypoxanthine (15 ml of 200 µM), prepared in 0.1 M phosphate buffer, pH 8.0, was circulated through a column containing 1.0g derivatized enzyme at a flow rate of 1.0 ml/min at 28§C. Specific activities of 0.660, 0.072 and 0.016 Units/mg of protein were demonstrable for the polyacrylamide gel beads, dacron and polyamide-11 derivatives, respectively. The action of these water insoluble enzyme derivatives on 6 mercaptopurine (15 ml of 660 µM) was also investigated, under the same experimental conditions, showing specific activites of 0.063 Units/mg, 0.574 µUnits/mg and 0.118 µUnitis/mg, respectively. The 6-mercaptopurine oxidative pathway catalyzed by immobilized xanthine oxidase on dacron stopped at the intermediate compound 6-mercaptopurine oxidative on dracon stopped at the intermediate compound, 6-mercapto-8-hydroxypurine, so that no 6-thiouric acid was produced, whereas the immobilized preparations using polyacrylamide gel beads and polyamide-11 behaved like the soluble enzyme, namely, 6-thiouric acid was the final product. The behavior of dracon-xanthine oxidase immobilized on these three supports was similar to the soluble enzyme. However, although its oxidation is stoichiometric for polyacrylamide gel beads and polyamide- 11 derivatives, and no xanthine formation is observed (steady-state equilibrium), under the action of the enzymedacron derivative the xanthine formation rate (0.164 µUnits/mg) is higher than the uric acid formation rate (0.017 µUnits/mg) compared to the hypoxanthine consumption (0.072 µUnits/mg). These findings suggest again that xanthine oxidase-dacron derivative is limited to the catalysis of oxidation of hypoxanthine carbon atom number 2 as in 6-mercaptopurine

Cytomegalovirus, human herpesvirus 6 and human T cell leukemia virus infection in renal transplanted patients in the northeast of Brazil

The seroprevalence of antibodies against cytomegalovirus (CMV), human herpesvirus 6 (HHV-6) and human T cell leukemia virus type 1 (HTLV-1), determined by ELISA and by fluorescence in 54 renal transplanted patients, was 96.2 per cent , 88.8 per cent and 11.1 per cent , respectively. These values are relatively high when compared with the results obtained for healthy individuals of the same age groups from Recife, Northeastern Brazil. Active CMV infection was detected by the presence of IgM antibodies and/or virus isolation in 13 (24 per cent ) patients. Kidney rejection and renal dysfunction were observed in 11 of these 13 patients, whereas 3 of 6 HTLV-1 antibody-positive individuals presented these complications. All HTLV-1 positive patients were also positive to IgG CMV and HHV-6 antibodies. The importance of the three viruses in this clinical condition is suggested by the high seropositivity rates compared with the healthy population. The group may also represent a potential source of HTLV-1 infection in this non-endemic area

Interference of therephthalic groups present in dacron with spectrophotometric azide determination

The determination of azida groups introduced into Dacron cannot be established by the method based on the Fe + -N3 complex because the therephthalic groups present in the polymer also react with Fe + to form a product with absorbance at 458 nm