Deciphering the role of Rhodnius prolixus CYP4G genes in straight and methyl-branched hydrocarbon formation and in desiccation tolerance.

Insect cuticle hydrocarbons are involved primarily in waterproofing the cuticle, but also participate in chemical communication and regulate the penetration of insecticides and microorganisms. The last step in insect hydrocarbon biosynthesis is carried out by an insect-specific cytochrome P450 of the 4G subfamily (CYP4G). Two genes (CYP4G106 and CYP4G107) have been reported in the triatomines Rhodnius prolixus and Triatoma infestans. In this work, their molecular and functional characterization is carried out in R. prolixus, and their relevance to insect survival is assessed. Both genes are expressed almost exclusively in the integument and have an expression pattern dependent on the developmental stage and feeding status. CYP4G106 silencing diminished significantly the straight-chain hydrocarbon production while a significant reduction - mostly of methyl-branched chain hydrocarbons - was observed after CYP4G107 silencing. Molecular docking analyses using different aldehydes as hydrocarbon precursors predicted a better fit of straight-chain aldehydes with CYP4G106 and methyl-branched aldehydes with CYP4G107. Survival bioassays exposing the silenced insects to desiccation stress showed that CYP4G107 is determinant for the waterproofing properties of the R. prolixus cuticle. This is the first report on the in vivo specificity of two CYP4Gs to make mostly straight or methyl-branched hydrocarbons, and also on their differential contribution to insect desiccation.

A fatty acid synthase gene (FASN3) from the integument tissue of Rhodnius prolixus contributes to cuticle water loss regulation.

Fatty acid synthase is a multifunctional enzyme involved in the formation of fatty acids. Despite the role of fatty acids in cell signalling and energy metabolism, and as precursors to pheromones and hydrocarbons that waterproof the cuticle, the insect fatty acid synthases have been scarcely studied. Here we perform the molecular characterization of three fatty acid synthase genes (fatty acid synthase RPRC000123, RPRC000269 and RPRC002909) in the Chagas disease vector, Rhodnius prolixus. Gene expression screening by reverse transcription quantitative PCR showed that RPRC000123 and RPRC002909 are expressed almost exclusively in the integument tissue whilst RPRC000269 is mostly expressed in the fat body and also in several body organs. Phylogenetic analysis, together with gene expression results, showed that RPRC000269, RPRC002909 and RPRC000123 are orthologues of Drosophila melanogaster fatty acid synthase 1 (FASN1), FASN2 and FASN3 genes, respectively. After RNA interference-mediated knockdown of RPRC000123, insects died immediately after moulting to the next developmental stage. However, mortality was prevented by placing the insects under saturated humidity conditions, suggesting that dehydration might play a role in the insects' death. Lipid analyses in RPRC000123-silenced insects showed reduced amounts of integument fatty acids and methyl-branched hydrocarbons, compared to controls. These data support an important role for FASN3 in the biosynthesis of the precursors to hydrocarbons that waterproof the insect cuticle.

Cuticular hydrocarbon pattern as a chemotaxonomy marker to assess intraspecific variability in Triatoma infestans, a major vector of Chagas' disease.

Triatoma infestans Klug (Hemiptera: Reduviidae) populations were sampled in various localities throughout most of the species' geographic range of distribution in Argentina, Bolivia, Paraguay and Peru. In order to contribute to understanding of the diversity and population structure of this major vector of Chagas' disease, cuticular hydrocarbon (CHC) profiles were analysed by capillary gas chromatography and variations evaluated by statistical methods of classification and ordination. High levels of intrapopulation variation were detected, along with low levels of variability among populations. Based on relative amounts of the major odd-numbered straight-chain hydrocarbons n-C27 to n-C33, two hydrocarbon phenotypes were evident, unequally distributed along the species' geographic range. Analysis of CHC patterns showed that T. infestans populations segregate into two major groups consisting of an Andean group, which comprises specimens from Peru and most parts of Bolivia, and a non-Andean group, which includes all specimens from Argentina and Paraguay, together with those from Tarija (Bolivia). Pyrethroid-resistant and -susceptible specimens were differentiated based on relative amounts of some straight and monomethyl-branched hydrocarbon components.

[Kt calculation as a quality indicator of haemodialysis adequacy]. / Cálculo del Kt como indicador de calidad en el área de adecuación en hemodiálisis.

The haemodialysis dose is a good marker of dialysis adequacy, and we usually monitor it with Kt/V measure. The dialysis dose monitored with Kt allows a better discrimination, detecting a percentage of the patients that perhaps do not get an adequate dose for their gender or body surface area after treatment with a minimum recommended dose of Kt/V. The objective of this study was to evaluate Kt as a clinical indicator referred to dialysis adequacy in the haemodialysis population. The aim was that more than 85% of the patients would achieve the recommended Kt target for their gender (at least 50 litres in men and 45 litres in women), or their body surface area. In each of the patients (mean 129) the Kt mean value was determined for three consecutive dialysis sessions, one every two months, during the follow-up period (14 months). At the beginning, the Kt/V value was on target (> 1.3) in 93.2% of the patients, but only in 58% according to Kt measure for their gender. After 4 months, we observed that 85% of patients' Kt target increased for their gender, but only 68% did if we used the Kt individualised for their body surface area. From month 6 to the end of the follow-up period, more than 85% of patients obtained an adequate Kt for their body surface area (p < 0.001). A significant increase of Kt mean (5.4 litres) was observed at the end of the study (p < 0.001). The usual dialysis prescription parameters were modified increasing blood flow rate (34.14 ml/min, p < 0.001), session effective duration (8.04 minutes, p < 0.001), dialyser surface area (24.1% of patients changed from helixone 1.3 to 1.6 m2, p < 0.001) and haemodialysis modality (56.8% of patients changed from conventional haemodialysis to on-line haemodiafiltration, p < 0.001). We conclude that monitoring dialysis dose with Kt is a good clinical measure of adequacy, and using it as a quality indicator can be done in line with the more demanding quality standards.

Adolescent nicotine-induced dendrite remodeling in the nucleus accumbens is rapid, persistent, and D1-dopamine receptor dependent.

Chronic nicotine exposure during adolescence induces dendritic remodeling of medium spiny neurons (MSNs) in the nucleus accumbens (NAcc) shell. While nicotine-induced dendritic remodeling has frequently been described as persistent, the trajectory of dendrite remodeling is unknown. Specifically, no study to date has characterized the structural plasticity of dendrites in the NAcc immediately following chronic nicotine, leaving open the possibility that dendrite remodeling emerges gradually over time. Further, the neuropharmacological mechanisms through which nicotine induces dendrite remodeling are not well understood. To address these questions, rats were co-administered chronic nicotine (0.5 mg/kg) and the D1-dopamine receptor (D1DR) antagonist SCH-23390 (0.05 mg/kg) subcutaneously every other day during adolescence. Brains were then processed for Golgi-Cox staining either 1 day or 21 days following drug exposure and dendrites from MSNs in the NAcc shell digitally reconstructed in 3D. Spine density was also measured at both time points. Our morphometric results show (1) the formation of new dendritic branches and spines 1 day following nicotine exposure, (2) new dendritic branches, but not spine density, remains relatively stable for at least 21 days, (3) the co-administration of SCH-23390 completely blocked nicotine-induced dendritic remodeling of MSNs at both early and late time points, suggesting the formation of new dendritic branches in response to nicotine is D1DR-dependent, and (4) SCH-23390 failed to block nicotine-induced increases in spine density. Overall this study provides new insight into how nicotine influences the normal trajectory of adolescent brain development and demonstrates a persistent form of nicotine-induced neuroplasticity in the NAcc shell that develops rapidly and is D1DR dependent.

A thermodynamic approach to the binding mechanisms of cefotaxime to serum albumins.

The interaction between cefotaxime and the serum albumin of several mammalian species (swine, rabbits, and sheep) at the albumin concentration of 5 x 10(-5) M was studied. Ultrafiltration and spectrophotometric determination of the free antibiotic in the filtrate were used. Binding percentages were determined, and the binding constants and number of sites at various temperatures were calculated. An increase in binding constants, especially in sheep albumin, and an increase in the number of sites from two to three were observed when compared to the results obtained at the physiological albumin concentration. The thermodynamic parameters of interaction varied between the following values: change in Gibbs energy, between -5.7 and -6.4 kcal.mol-1; change in enthalpy, between -6.7 and -9.6 kcal.mol-1; and change in entropy, between -3.1 and -11.2 entropy units. The binding constants increased considerably as the ionic strength of the solution decreased although the number of binding sites remained unchanged. These results indicate the existence of ionic and hydrogen bonds. The possibility of a small contribution from hydrophobic bonds cannot be ruled out.

[Biodegradation of a lipid-rich effluent by native bacteria]. / Biodegradación de efluente rico en lípidos por bacterias autóctonas.

From samples of effluent derived from a biological treatment plant of a mayonnaise and margarine producing factory, several bacteria strains presenting high lipolytic activities were isolated. The strain having the highest activity was used for treating a typical final effluent and the results obtained were compared with those achieved with Yarrowia lipolytica and Saccharomycopsis lipolytica strains. The isolated strain showed the highest specific capacity for reducing chemical oxygen demand (COD).

[Production of cyanide in the rat liver from 3-aminopropionitrile]. / Production de cyanure dans le foie de rat à partir de 3-aminopropionitrile.

CN- Production was investigated from a saturated mononitrile, 3-aminopropionitrile, in small liver pieces and liver homogenates. Results show that CN- production is a function of time and of the concentration of active ingredient, with a trend to saturation in both cases. Similarly, cell integrity is not required for the biotransformation of 3-aminopropionitrile to occur. Cofactors such as NADPH must be present to reach high level activities. The effect of free radicals scavengers such as mannitol and DMSO was also studied.

The interaction of cefotaxime with the serum albumin of several mammalian species.

1. The interaction of cefotaxime with the serum albumin of several mammalian species; horses, swine, sheep, dogs and rabbits, was studied comparatively. The technique of ultrafiltration and spectrophotometric determination of the free antibiotic in the filtrate was used. 2. Binding percentages, which vary according to the species studied, were found to be higher in swine and rabbit albumins (between 92 and 81%) and lower for sheep, dog and horse albumins (between 67 and 52%). 3. The number of binding sites is usually close to 2; in the case of the horse it is 2.43. The apparent binding constants are: swine, 1.61 x 10(4) M-1; rabbit, 1.19 x 10(4) M-1; sheep, 2.33 x 10(3) M-1; dog, 2.00 x 10(3) M-1; horse, 1.42 x 10(3) M-1. The Scatchard model was used for data analysis. 4. Possible consequences of this interaction regarding clinical use of cefotaxime on different species are discussed.

Possible biotransformation mechanism of 3-aminopropionitrile by means of free radicals.

The possible role of free radicals in the transformation of 3-aminopropionitrile giving rise to the liberation of cyanide was studied. Rat liver homogenates were cellularly fractionated. It was confirmed that the transformation occurred mainly in the microsomal fraction. The different isozyme forms of cytochrome P-450 were then partially purified and their velocity and affinity constants determined. It could be deduced that the cyanide-forming activity was mainly due to the LM3C cytochrome form. Dimethylsulfoxide was a potent competitive transformation inhibitor while mannitol was a moderate one. An OH radical generator inorganic system was also shown to liberate cyanide from 3-aminopropionitrile. In view of these results, a transformation mechanism of 3-aminopropionitrile by means of OH free radicals is suggested with the formation of cyanide anion in a cell-free organic system as well as in the microsomal fraction of rat liver.

[Guide for the prevention of renal diseases during and after childhood]. / Guía para la prevención de las enfermedades renales en y desde la infancia.

Kidney disease Prevention in childhood can be made from three levels. In the first level or Primary Prevention one must prevent kidney disease taking steps for "Kidney Health" promotion: environmental factors, nourishing, sanitary education and preventive pediatrics. Secondary Prevention lies in the correct diagnostic during first years in life and in a suitable treatment of the kidney diseases, especially in children to have a kidney failure risk: obstructive uropathy and vesicoureteral reflux. Tertiary Prevention deals with aggravating factors in an established Kidney chronic failure, and its prevention includes: normoproteic diet, phosphorus restriction, arterial hypertension control and nutritional and pharmacological steps to reduce the hyperlipidemia.

[Infrequent manifestations of Henoch-Schonlein purpura]. / Manifestaciones infrecuentes en la púrpura de Schönlein-Henoch.

We review the cases of 148 children with Henoch-Schönlein purpura diagnosed in a period of seventeen years (from 1975 to 1992). Thirteen cases (8.7%) of unusual clinical manifestations were found: testicular affection in six cases (7.6% of the males); IgA nephropathy in four (2.7%); exudative enteropathy in two (1.3%); duodenal syndrome in two; previous abdominal manifestation which led to surgical procedures in one (0.7%) and another case with detachment of the retina. These clinical findings are analyzed and the possibility of unnecessary therapeutic acts is discussed.

A radiaçäo laser arseneto de gálio (AsGa) na regeneraçäo do nervo radial submetido a reparaçäo cirúrgica secundária / The galium arsenide (GaAs) laser radiation in the radial nerve regeneration submitted to secundary surgical repair

Vinte e quatro cäes adultos, sem raça definida, foram separados em quatro grupos e submetidos a neurotomia bilateral do nervo radial, em nível do terço distal do úmero e, 21 dias após, sofreram anastomose epineural secundária, término-terminal. Nos 10 dias subseqüentes à neuroanastomose, o membro esquerdo de todos os cäes foi irradiado com laser arseneto de gálio no intuito de investigar sua influência na regeneraçäo do nervo. O membro contralateral serviu como testumunha. A recuperaçäo funcional foi verificada através da característica da deambulaçäo, testes de sensibilidade e avaliaçäo motora. Foram efetuadas biópsias bilaterais, na regiäo de anastomose, aos 10 dias (grupo A), 30 dias (grupo B), 60 dias (grupo C) e 90 dias (grupo D) após a reconstituiçäo cirúrgica, para estudo morfológico em microscopia óptica. A proliferaçäo de tecido conjuntivo na linha de anastomose é a complicaçäo mais séria no processo de regeneraçäo nervosa. A radiaçäo laser diminui a intensidade da resposta inflamatória ao fio de sutura, mas pode contribuir para a formaçäo de neuroma mais exuberante

Biodegradación de efluente rico en lípidos por bacterias autóctonas / Biodegradation of lipidh-rich effluent by native bacterium

A partir de muestras del efluente de una fábrica de tratamiento biológico existente en una fábrica de mayonesa y margarinas se aislaron cepas de bacterias caracterizadas por poseer una alta actividad lipolítica. Con la cepa que presentó la mayor actividad se efectuaron estudios de tratamiento del efluente final de la fábrica. Su comportamiento se comparó con cepas de reconocida actividad lipolítica (Yarrowia lipolytica y Saccharomycopsis lipolytica). La cepa autóctona aislada demostró poseer una capacidad de disminución de la demanda química de oxígeno específica muy superior a las otras ensayadas