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Semicontinuous cultures of Scenedesmus obliquus in artificial wastewater were maintained with 30% and 40% daily dilutions and under a 14:10 h light-dark cycle, with temperatures of 25.5 and 17 degrees C during light and dark hours. Under this regime, the production of organic biomass was 39.3 and 25.2 mg l(-1)d(-1) for the 30% and 40% dilutions, and 24.9 and 16.7 mg l(-1)d(-1) of single-cell proteins. Most of the nitrogen removal took place during the light hours, with daily totals of 9.27 and 8.45 mg l(-1) for the 30% and 40% dilutions. With the former, 43.7% of the nitrogen removed was recycled by the microalgae into proteins and other organic nitrogen cell contents, but this efficiency decreased to 26.4% when the dilutions were raised to 40%.

The aim of this work is the description of virtual environments designed to apply exposure therapy in the treatment of panic disorder and agoraphobia. The program allows the simultaneous exposure to two different kinds of stimuli usually avoided by panic disorder and agoraphobia sufferers (external and interoceptive). The characteristics of the virtual environments are described, as well as the target behaviors that can be simulated with these virtual environments.

Background: The risk of presenting with oesophageal cancer is associated with Barrett's oesophagus, with a higher prevalence in some Asian and African countries. Human papillomavirus (HPV) DNA has been identified in oesophageal carcinomas, which share common features with cervical cancers and originate in stratified epithelium., Materials and Methods: Sixty-eight paraffin-embedded tissue biopsies were selected from Mexican patients: 17 from oesophageal cancers, 28 from cases of Barrett's oesophagus and 23 from cases of oesophagitis. HPV protein was detected immunohistochemically and the presence and types of HPV DNA were assessed by polymerase chain reaction., Results: HPV DNA-positive results were found in 26% of samples of oesophagitis, 96% of samples of Barrett's oesophagus and 88% of samples of oesophageal cancers. HPV viral types 6 and 11 were prevalent. HPV protein was detected in 41 samples (60%)., Conclusion: Mexico has a high prevalence of HPV in premalignant and malignant oesophageal diseases compared with other countries.

Panic disorder with agoraphobia (PDA) is considered an important public health problem. The efficacy of cognitive-behavioral therapy (CBT) for PDA has been widely demonstrated. The American National Institute of Health recommended Cognitive-Behavioral programs as the treatment of choice for this disorder. This institution also recommended that researchers develop treatments whose mode of delivery increases the availability of these programs. Virtual Reality based treatments can help to achieve this goal. VR has several advantages compared with conventional techniques. One of the essential components to treat these disorders is exposure. In VR the therapist can control the feared situations at will and with a high degree of safety for the patient, as it is easier to grade the feared situations. Another advantage is that VR is more confidential because treatment takes place in the therapist's office. It is also less time consuming as it takes place in the therapist's office. Considering the wide number of situations and activities that agoraphobic patients use to avoid, VR can save time and money significantly. Another advantage in treating PDA using VR is the possibility of doing VR interoceptive. VR could be a more natural setting for interoceptive exposure than the consultation room because we can elicit bodily sensations while the patient is immerse in VR agoraphobic situations. Finally, we think that VR exposure can be a useful intermediate step for those patients who refuse in vivo exposure because the idea of facing the real agoraphobic situations is too aversive for them. In this chapter we offer the work done by our research team at the VEPSY-UPDATED project. We describe the VR program we have developed for the treatment of PDA and we summarize the efficacy and effectiveness data of a study where we compare a cognitive-behavioral program including VR for the exposure component with a standard cognitive-behavioral program including in vivo exposure and with a waiting list control condition. Our findings support the efficacy and effectiveness of VR for the treatment of PDA.

ATP-regenerating enzymes may have an important role in maintaining ATP levels in mitochondria-like kinetoplast organelle and glycosomes in parasitic protozoa. Adenylate kinase (AK) (ATP:AMP phosphotransferase) catalyses the reversible transfer of the gamma-phosphate group from ATP to AMP, releasing two molecules of ADP. This study describes cloning and functional characterization of the gene encoding AK2 from a genomic library of Leishmania donovani and also its expression in leishmania promastigote cultures. AK2 was localized on an approximately 1.9-Mb chromosomal band as a single copy gene. L. donovani AK2 gene is expressed as a single 1.9-kb mRNA transcript that is developmentally regulated and accumulated during the early log phase. The overexpression of L. donovani AKgene in Escherichia coli yielded a 26-kDa polypeptide that could be refolded to a functional protein with AK activity. The recombinant protein was purified to apparent homogeneity. Kinetic analysis of purified L. donovani AK showed hyperbolic behaviour for both ATP and AMP, with Km values of 104 and 74 microM, respectively. The maximum enzyme activity (Vmax) was 0.18 micromol.min(-1).mg(-1) protein. P1,P5-(bis adenosine)-5'-pentaphosphate (Ap5A), the specific inhibitor of AK, competitively inhibited activity of the recombinant enzymes with estimated Ki values of 190 nM and 160 nM for ATP and AMP, respectively. Ap5A also inhibited the growth of L. donovani promastigotes in vitro which could be only partially reversed by the addition of ADP. Thus, presence of a highly regulated AK2, which may have role in maintenance of ADP/ATP levels in L. donovani, has been demonstrated.

The SP-RING or Miz zinc finger domain that is related to the classical RING-finger motif, defines a class of proteins that can act as E3-like factors in the pathway of small ubiquitin-related modifier (SUMO) conjugation. This family includes the mammalian protein inhibitor of activated STAT (PIAS) proteins and related proteins from lower eukaryotes. Here we report the existence of a gene in Leishmania infantum, present as two identical copies placed upstream of each MAT2 gene copy, and transcribed as a single approximately 2.2 kb mRNA both in the logarithmic and stationary phases of the promastigote stage. This gene encodes a 47 kDa protein that has been named LORIEN. LORIEN is circumscribed to the cell periphery and it is antigenic during L. infantum infection of dogs and hamsters. Strikingly, this novel protein contains a highly conserved SP-RING/Miz zinc finger domain, raising the possibility that a SUMO or ubiquitin-like system may exist in this microorganism.

Iodonium ions liberated from bis(pyridine)iodonium(I) tetrafluoroborate react with ortho-alkynyl-substituted carbonyl compounds and different nucleophiles to give valuable iodinated heterocycles at room temperature, through a new and metal-free reaction sequence. Interestingly, the nature of the nucleophile can be widely modified, and not only alcohols but also several carbon-based nucleophiles can be nicely used.

A common feature shared by type I DNA topoisomerases is the presence of a "serine, lysine, X, X, tyrosine" motif as conventional enzyme active site. Preliminary data have shown that Leishmania donovani DNA topoisomerase I gene (LdTOP1A) lacked this conserved motif, giving rise to different theories about the reconstitution of an active DNA topoisomerase I in this parasite. We, herein, describe the molecular cloning of a new DNA topoisomerase I gene from L. donovani (LdTOP1B) containing the highly conserved serine, lysine, X, X, tyrosine motif. DNA topoisomerase I activity was detected only when both genes (LdTOP1A and LdTOP1B) were co-expressed in a yeast expression system, suggesting the existence of a dimeric DNA topoisomerase I in Leishmania parasites.

Methionine adenosyltransferase (MAT, EC 2.5.1.6)-mediated synthesis of S-adenosylmethionine (AdoMet) is a two-step process consisting of the formation of AdoMet and the subsequent cleavage of the tripolyphosphate (PPPi) molecule, a reaction induced, in turn, by AdoMet. The fact that the two activities, AdoMet synthesis and tripolyphosphate hydrolysis, can be measured separately is particularly useful when the site-directed mutagenesis approach is used to determine the functional role of the amino acid residues involved in each. The present report describes the cloning and subsequent functional refolding, using a bacterial expression system, of the MAT gene (GenBank accession number AF179714) from Leishmania donovani, the etiological agent of visceral leishmaniasis. The absolute need to include a sulfhydryl-protection reagent in the refolding buffer for this protein, in conjunction with the rapid inactivation of the functionally refolded protein by N-ethylmaleimide, suggests the presence of crucial cysteine residues in the primary structure of the MAT protein. The seven cysteines in L. donovani MAT were mutated to their isosterical amino acid, serine. The C22S, C44S, C92S and C305S mutants showed a drastic loss of AdoMet synthesis activity compared to the wild type, and the C33S and C47S mutants retained a mere 12% of wild-type MAT activity. C106S mutant activity and kinetics remained unchanged with respect to the wild-type. Cysteine substitutions also modified PPPi cleavage and AdoMet induction. The C22S, C44S and C305S mutants lacked in tripolyphosphatase activity altogether, whereas C33S, C47S and C92S retained low but detectable activity. The behavior of the C92S mutant was notable: its inability to synthesize AdoMet combined with its retention of tripolyphosphatase activity appear to be indicative of the specific involvement of the respective residue in the first step of the MAT reaction.

In order to define the main diseases of the elderly and a possible changes of mortality causes at Hospital General of Mexico, SSA, the authors studied 586 autopsy reports of individuals over sixty years old, deceased between 1960 and 1965 and of 625 individuals of similar characteristics deceased between 1981 and 1985. The analysis of diseases showed qualitative and quantitative changes in the ten principal causes of death at each period: some of the most frequent diseases in the 60's, for instance, amebiasis, were not included among the then principal causes of death in the 80's. On the other hand, malignant neoplasms persisted as one of the principal death causes in both periods, but the most frequent carcinoma in the 60's, gastric carcinoma, was substituted in the 80's by bronchogenic carcinoma. This study suggests that great technical and sanitary interventions are necessary to promote health of third age persons, an increasing but poorly protected population in our country.

From 1972 to October 1982 we have observed 39 cases of mycetoma in the Skin Department of the Hospital del Milagro, Salta (Argentina). The diagnosis was based on the clinical aspect, mycological studies and in most cases histopathology was done as well. The mayoritary of the patients were farmers. From the clinical point of view there si a true prevalence of Nocardia Brasiliensis. Most of the mycetomas can be found in the lower limbs. Some of the patients presented quite severe lesions and eight of them had bone involvement. The combination of long action sulphas with sulphonas has been efficient enough in the treatment of mycetomas caused by Nocardia Brasiliensis.