Search for antibodies to Taenia solium cysticerci in paediatric patients with seizures.

Neurocysticercosis is a leading cause of seizures in adults, but in paediatric patients, the diagnosis is controversial. The aim of this study was to search for antibodies to Taenia solium cysticerci in paediatric patients with seizures. We retrospectively studied a cohort of 41 serum samples from paediatric patients and 40 serum samples from healthy children. Antibodies were analysed by ELISA (vesicular fluid) and by Western blot (glycoproteins). Clinical, image and socio-demographic data were obtained from the medical records. The frequency of positive by ELISA was of 12% (n=5) in patients with seizures, while no positive samples were found in the healthy group. Results of Western blot were negatives. The analysis of the medical records showed a cyst of unknown origin in 2/5 ELISA positive samples. According to the diagnostic criteria for neurocysticercosis, three minor criteria (positive serology, active seizures and compatible image) were associated to an epidemiological condition (Mexico is endemic for neurocysticercosis); thus, the probable frequency of neurocysticercosis in the studied sample of patients with seizures was 4.9% (2/41 patients). The three remaining positive samples were associated with problems of noninfectious origin. The positivity was associated with the identification of cysts by magnetic resonance imaging (p = 0.047; chi-square), but found no association with the socio-economic characteristics of the patients, family history or to clinical symptoms. In conclusion, scarce frequency of antibodies to T. solium cysticerci was determined in paediatric patients with seizures. The low prevalence of antibodies detected in children is an indirect indicator of the interruption of T. solium transmission. Further studies are needed to design an algorithm for the conclusive diagnosis of seizures.

Functional arginine residues and carboxyl groups in the adenosine triphosphatase of the thermophilic bacterium PS-3.

Treatment of purified ATPase of the thermophilic bacterium PS-3 with the arginine reagent phenylglyoxal or with Woodward's reagent K, gave complete inactivation of the enzyme. The inactivation rates followed apparent first-order kinetics. The apparent order of reaction with respect to inhibitor concentrations gave values near to 1 with both reagents, suggesting that inactivation was a consequence of modifying one arginine or carboxyl group per active site. ADP and ATP strongly protected the thermophilic ATPase against both reagents. GDP and IDP protected less, whilst CTP did not protect. Experiments in which the incorporation of [14C]phenylglyoxal into the enzyme was measured show that extrapolation of incorporation to 100% inactivation of the enzyme gives 8-9 mol [14C]phenylglyoxal per mol ATPase, whilst ADP or ATP prevent modification of about one arginine per mol.

Preparative purification of the subunits of chloroplast and Rhodospirillum rubrum coupling factors by flat-bed electrofocusing in granulated gels.

A rapid method for the preparative purification of the subunits of oligomeric proteins like chloroplast and Rhodospirillum rubrum coupling factors is presented. It involves the dissociation of the protein in urea and the separation of its subunits by isoelectric focusing in flat-beds of Sepharose CL-4B or Sephadex G-75 superfine, in the presence of urea and in an overnight run. Using this procedure in the pH range 5-7, we have purified to homogeneity the alpha, beta and delta subunits of chloroplast coupling factor, as well as the alpha and beta subunits of Rhodospirillum rubrum coupling factor. The full separation of the gamma and epsilon subunits of chloroplast coupling factor, which focused at the same pH, was achieved by gel filtration high-performance liquid chromatography.

A fast and sensitive micromethod for the manual sequencing of peptides using O-phthalaldehyde as derivatizing reagent.

A general procedure for the manual sequencing of peptides using the fluorogenic reagent O-phthalaldehyde (OPA) is described. The method can be applied in two different ways. One of them involves back hydrolysis of the anilinothiazolinones resulting from the Edman degradation of the peptide and subsequent detection of the free amino acids as OPA derivatives. The other is a subtractive analysis in which the amino acid composition of the remaining peptide is determined after each degradation cycle. The direct procedure can be coupled to the subtractive one in order to assure the accuracy of the sequence analysis. The method is fast and simple, and allows determination of 10 pmol of amino acid per cycle using standard reagents and instrumentation. Sensitivity can be greatly enhanced provided that ultrapure chemicals are employed. Small peptides (8-10 residues) were sequenced from 200 pmol sample, using a high-performance liquid chromatography assembly coupled to a fluorescence detector.

Antimicrobial peptides as parasiticidal against human trypanosomatids: mechanisms of action and current status in development.

Trypanosomes cause a variety of tropical diseases that affect the livelihood of individuals worldwide. The currently used pharmaceutical treatments rely on chemotherapy. However, many of these drugs are very expensive, and highly toxic. In addition, parasite resistance to several of the therapeutic drugs used is increasing. Therefore, there is a growing need for new control measures for many of these diseases. One new approach is the use of antimicrobial peptides (AMPs) to disease control, since these peptides can be used as potential anti-parasite effector molecules. This review summarizes and discusses the parasiticidal properties of AMPs for treating trypanosome infections, highlighting their mechanisms of action and current status in development.

Morphometric analysis of nodules in human onchocerciasis collected in communities of the southern Chiapas focus, México.

Human onchocerciasis is a disease that remains as an important public health problem. The morphometric and physical characteristics of 363 Onchocerca volvulus nodules collected in the major endemic focus of onchocerciasis in Southern Chiapas (Soconusco), was assessed. In the present work we found that treatment the morphometry of 363 onchocercal nodules preserved in a 67% glycerol solution was determined by measuring the length, width and thick of each nodule with a Vernier caliper. The mass was determined with an analytical balance and the volume by measuring the water displacement, while the specific gravity was calculated by dividing mass over the volume. Statistical analysis was calculated for each parameter. The results showed that the nodules were rather longer than wider or thicker. Morphometric characteristics were 9.87 +/-3.70 (mean +/- standard deviation), 7.52 +/- 2.81, and 4.62 +/-+/- 2.06 mm for length, width and thick respectively. In regard to the shape, 62.81% of the nodules showed a lenticular shape, while 18.18% were spherical and 19.01% were ovoid. Based on the distribution of frequencies of the length, the nodules were classified in three groups: the "small" (5.77 +/- 0.73 mm; n = 104, 28.65%), the "medium" group (9.86 +/- 2.05 mm; n = 203 nodules, 55.92%), and the group of the "big" ones (16.03 +/- 1.91 mm; n = 56, 15.43%). Moreover, the physical characteristics were: for the mass 0.33 +/- 0.24 g, the volume of displaced water was 0.28 +/- 0.26 ml, and the specific gravity was 1.10 +/- 0.55 g/ml. The results indicated that most of the Mexican Onchocerca nodules have a lenticular shape with average size of 10x7x5 mm, which is useful in the knowledge of the genus biodiversity and can be taken as a parameter in clinical or epidemiological trials, where onchocerciasis remains as a public health problem.

A study on parasites in Mexican rheumatic disease patients.

Blastocystis hominis is a common human parasite with infection rates up to 50% in developing countries, and giardiasis is the commonest intestinal one in Mexico. No doubt, various parasites as Giardia lamblia and Entamoeba histolytica can cause rheumatic diseases. This study coproparasitoscopic analysis evaluated the cysts by B. hominis, G. lamblia, E. hartmani, E. coli and E. histolytica in Mexican rheumatic disease patients. Also, ELISA was used to detect E. histolytica, Ascaris lumbricoides, Toxocara canis, and Trichinella spiralis in Mexican patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Thirty-six patients (24 with AS and 12 with RA) and 77 healthy control individuals were enrolled in this study. The frequencies of protozoan cysts were comparable in rheumatic disease patients (AS and RA) and healthy control donors (33 and 25 vs. 26%, respectively; p > 0.05). The frequency of antibodies to T. canis was significantly higher in AS patients than in healthy control donors (16 vs. 2.6%, respectively; p = 0.027), whereas no differences were observed for the prevalence of antibodies for the other parasites (E. histolytica, A. lumbricoides and T. spiralis) (p > 0.05). This information indicates the need to intensify educational efforts for the prevention of parasite infections associated with AS disease that cannot be controlled only by drugs.

Involvement of sulfhydryl groups in the activation mechanism of the ATPase activity of chloroplast coupling factor 1.

Activation of the ATPase activity and the exposition of a new adenine nucleotide binding site of chloroplast coupling factor 1 (CF1) by dithioerythritol at 25 degrees C were reversed by oxidants. The ATPase activity elicited by heat (63 degrees C, 4 min) was slightly inhibited by oxidants and was partially additive with the activity induced by dithioerythritol. Titration of the thiols of CF1 and determination of their subunit distribution before and after activation by dithioerythritol show an increase of the free groups from 8 to 10 with the appearance of the 2 new thiols on the gamma subunit. These thiols were available to reagents in nondenatured enzyme and were reoxidized to a disulfide bond by iodosobenzoate or CuCl2. It is concluded that the mechanisms of CF1 activation by dithioerythritol and by heat are different and that the former involves a net reduction of a disulfide bond of the gamma subunit.

Changes in activity and structure of the chloroplast proton ATPase induced by illumination of spinach leaves.

Photophosphorylating activity of chloroplasts rapidly prepared from preilluminated spinach leaves was higher than the activity of chlorplasts from leaves kept in the dark. Higher Vmax values were obtained with the former when either ADP or Pi concentrations were varied. The rate of decay of the in vivo light-activated Mg2+-ATPase was highly dependent on temperature, increasing with it. At 0 degree C it was stable for 40 min or more. The decay at 25 degrees C was prevented by 5 mM ATP or 50 mM dithioerythritol while ADP or Pi did not affect it. Gramicidin or iodosobenzoate induced a very rapid decay even at 0 degree C. Coupling factor 1 with a manifest and stable Ca2+-ATPase activity was solubilized from chloroplasts activated by light in vivo. Incubation of chloroplasts from preilluminated leaves with N-[3H]ethylmaleimide resulted in an inhibition of Ca2+-ATPase activity and in the incorporation of radioactivity into the gamma subunit of coupling factor 1 that was larger than that of chloroplasts from leaves kept in the dark. The results show that activation in vivo of the proton ATPase was manifested by higher phosphorylating and Mg2+-ATPase activities and requires both an electrochemical proton gradient and a redox change of at least one disulfide bond of its gamma subunit.

An essential carboxyl group at the nucleotide binding site of ferredoxin-NADP+ oxidoreductase.

Woodward's reagent K (N-ethyl-5-phenylisoxazolium-3'-sulfonate) inactivated both soluble and membrane bound-ferredoxin-NADP+ reductase of spinach chloroplasts. Either NADP+ or NADPh afforded complete protection against modification. Ki and the apparent Kd for protection afforded by NADP+ depended on the ionic strength of the medium. Nucleophylic displacement of reagent bound to the soluble enzyme by [14C]glycine ethyl ester showed that 5 to 6 carboxyl groups/flavin were modified when the diaphorase activity was completely inhibited. In differential labeling experiments using NADP+ as protective agent, it was shown that enzyme inactivation was due to blocking of only 1 carboxyl group/mol. Derivatized reductase did not bind pyridine nucleotides. Protection by NADP+ of the membrane-bound reductase was higher, and the apparent Kd for NADP+ lower, in the light than in the dark. Inactivation increased abruptly with the external pH, indicating a progressive exposure of the carboxyl group as the pH was raised. The results presented suggest (a) the existence of a light-driven conformational change and a pH-dependent transition in membrane-bound ferredoxin-NADP+ reductase; (b) the presence of an essential carboxyl residue in the nucleotide binding site of the reductase.