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Summary Physics-based and empirical rate-time models inherently assume constant bottomhole flowing pressure (BHP), an assumption that may not hold for many unconventional wells. Hence, applying these models without accounting for BHP variations might lead to inaccurate (a) flow regime identification, (b) estimation of the parameters of these models, and (c) estimated ultimate recovery (EUR) and drainage volumes. This study evaluates and compares the predictions of rate-time relations including and ignoring corrections for time-varying BHP for both synthetic and shale gas wells. We generate a real gas synthetic case with errors in the time-varying BHP. First, we convert pressures into pseudopressures. Second, we deconvolve the pseudopressure history by applying the regularized exponential basis function inverse scheme to obtain an equivalent rate—the unit-pseudopressure-drop rate at standard conditions—at constant BHP. Third, we history match the production using the scaled single-phase compressible fluid physics-based model for three different approaches: (a) using rate-time-pressure data with rate-pseudopressure deconvolution, (b) using rate-time-pressure data using just rate-pressure deconvolution, and (c) using only rate-time data. Finally, we compare the results in terms of their history matches and estimated reservoir parameters. We conclude by illustrating the application of this procedure to shale gas wells. For the synthetic case, the fit of the single-phase compressible fluid rate-time model using rate-pseudopressure deconvolution can accurately estimate the original gas in place, characteristic time, gas permeability, and fracture half-length. In contrast, considerable errors are noted when either using rate-pressure deconvolution or failing to account for variable BHP. Regarding the shale gas examples, the rate-pseudopressure deconvolution scheme accurately identifies the flow regimes present in the well, which can be difficult to detect by only analyzing rate-time data. For this reason, the fits of the scaled single-phase compressible fluid model using only rate-time result in unreasonably large estimates of the reservoir parameters and EUR. In contrast, the application of rate-pseudopressure deconvolution constrains the fits of the single-phase compressible fluid model yielding more realistic estimates of the time of end of transient flow, and EUR. This paper illustrates the application of a workflow that accounts for variable BHP by estimating an equivalent constant unit-pseudopressure-drop gas rate (at standard conditions). We illustrate the workflow for a particular decline-curve model, but the workflow is general and can be applied to any rate-time model. The approach history matches and forecasts the production of unconventional gas reservoirs using rate-time models more accurately than assuming constant BHP.

Summary Extrapolation of history matched single-phase flow solutions is a common practice to forecast production from tight-oil reservoirs. Nonetheless, this approach (a) omits multiphase flow effects that exist below bubblepoint conditions and (b) has not included the quantification of the uncertainty of the estimated ultimate recovery (EUR). This work combines a new two-phase (oil and gas) flow solution within a Bayesian framework to address the uncertainty in the EUR. We illustrate the application of the procedure to tight-oil wells of west Texas. First, we combine the oil and the gas flow equations into a single dimensionless two-phase flow equation. The solution is a dimensionless flow rate model that can be easily scaled using two parameters: hydrocarbon pore volume and characteristic time. Second, this study generates the probabilistic production forecasts using a Bayesian approach in which the parameters of the model are treated as random variables. We construct parallel Markov chains of the parameters using an adaptative Metropolis-Hastings (M-H) Markov chain Monte Carlo (MCMC) for this purpose. Third, we evaluate the robustness of our inferences using posterior predictive checks (PPCs). Finally, we quantify the uncertainty in the EUR percentiles using the bootstrap method. The results of this research are as follows. First, this work shows that EUR estimates based on single-phase flow solutions will consistently underestimate the ultimate oil recovery factors in solution-gas drives where the reservoir pressure is less than the bubblepoint. The degree of underestimation will depend on the reservoir and flowing conditions as well as the fluid properties. Second, the application of parallel Markov chains using an adaptative M-H MCMC scheme that addresses the correlation between the model’s parameters solves the issues of mixing and autocorrelation of Markov chains and, thus, it speeds up speeding up the convergence of the Markov chains. Third, we generate replicated data from our posterior distributions to assess the robustness of our inferences (PPCs). Finally, we use hindcasting to calibrate and strengthen our inferences. To our knowledge, all these approaches are novel in EUR forecasting. Using a Bayesian framework with a low-dimensional (two-parameter) physics-based model provides a fast and reliable technique to quantify the uncertainty in production forecasts. In addition, the use of parallel chains with an adaptative M-H MCMC accelerates the rate of convergence and increases the robustness of the method.

Summary A common approach to forecast production from unconventional reservoirs is to extrapolate single-phase flow solutions. This approach ignores the effects of multiphase flow, which exist once the reservoir pressure falls below the bubble/dewpoint. This work introduces a new two-phase (oil and gas) flow solution suitable to extrapolating oil and gas production using scaling principles. In addition, this study compares the application of the two-phase and the single-phase solutions to estimates of production from tight-oil wells in the Wolfcamp Formation of west Texas. First, we combine the oil and the gas flow equations into a single two-phase flow equation. Second, we introduce a two-phase pseudopressure to help linearize the pressure diffusivity equation. Third, we cast the two-phase diffusion equation into a dimensionless form using inspectional analysis. The output of the model is a predicted dimensionless flow rate that can be easily scaled using two parameters: a hydrocarbon pore volume and a characteristic time. This study validates the solution against results of a commercial simulator. We also compare the results of both the two-phase and the single-phase solutions to forecast wells. The results of this research are the following: First, we show that single-phase flow solutions will consistently underestimate the oil ultimate recovery factors (URFs) for solution gas drives. The degree of underestimation will depend on the reservoir and flowing conditions as well as the fluid properties. Second, this work presents a sensitivity analysis of the pressure/volume/temperature (PVT) properties, which shows that lighter oils (more volatile) will yield larger recovery factors for the same drawdown conditions. Third, we compare the estimated ultimate recovery (EUR) predictions for two-phase and single-phase solutions under boundary-dominated flow (BDF) conditions. The results show that single-phase flow solutions will underestimate the ultimate cumulative oil production of wells because they do not account for liberation of dissolved gas and its subsequent expansion (pressure support) as the reservoir pressure falls below the bubblepoint. Finally, the application of the two-phase model provides a better fit when compared with the single-phase solution. The present model requires very little computation time to forecast production because it only uses two fitting parameters. It provides more realistic estimates of URFs and EURs, when compared with single-phase flow solutions, because it considers the expansion of the oil and gas phases for saturated flow. Finally, the solution is flexible and can be applied to forecast both tight-oil and gas condensate wells.

Many researchers became interested in the discovery of Bi2Sr2CaCu2O8+δ oxides with critical temperature of around 80 K. It is known that the critical temperature is related to the CuO2 planes of the material. For this reason, the study of the interstitial oxygen in these oxides is of great relevance. The samples were prepared by means of conventional solid state reactions, through the stoichiometric mixture of precursory powders. After the sinterization, the samples were submitted to measurements of density, electrical resistivity, x-ray diffraction, scanning electron microscopy and energy dispersion spectroscopy, with the objective of performing their characterization. The measurements of mechanical spectroscopy were performed by a torsion pendulum. The results show three relaxation processes in the temperature range of 200 and 700 K, with activation energy of approximately 0.9 eV, which has been attributed to the dynamics of the interstitial oxygen present in the material.

Existe una preocupación sobre el nivel de competencia coordinativa de los escolares en la Educación Secundaria Secundaria (ESO) española y su impacto en sus actividades cotidianas y en su salud. El objetivo de este estudio fue evaluar la coordinación de una muestra de escolares de primero de la ESO. Participaron 120 escolares, 65 chicos y 55 chicas, de cuatro institutos de Educación Secundaria de la Comunidad de Madrid, de edades comprendidas entre 12 y 14 años. Todos los participantes llevaron a cabo el test de coordinación corporal (KKTK) diseñado para detectar los problemas de coordinación motriz en las edades escolares. Los resultados permitieron el establecimiento de tres grupos de coordinación: normal (38,3%), sintomático (31,35%) y problemático (30%). Estos resultados indicaron que un 61,7% de los escolares participantes en este estudio presentaban algún tipo de dificultad de coordinación, al encontrarse en los niveles sintomático y problemático. La presencia de las chicas en el nivel sintomático y problemático fue predominante. Los resultados confirman que los problemas de coordinación motriz existen en la población escolar y que no solo suponen un problema educativo sino también de salud, ya que impiden estilos de vida más activos entre los adolescentes, especialmente entre las chicas. Palabras clave: Estilos de vida. Educación Secundaria. Adolescencia. Trastornos evolutivos de la coordinación. Desarrollo motor.

Pulsed-field gel electrophoresis has been applied to analyze the karyotypic variability among colpodid ciliates. The 18S ribosomal gene was found at different locations in the electrophoretic pattern, and these size variations in the ribosomal DNA subchromosomal molecule seem to be species specific. This could potentially be a useful new tool with which to differentiate colpodid ciliates.

ide; protein kinase C; angiotensin converting enzyme; mesangial cell; diabetic nephropathy. Background. Oxidative stress is considered to play a role in the pathogenesis of diabetic nephropathy. Angiotensin-converting enzyme (ACE ) inhibitors are hypotensive drugs with a well-known effect in pre- Introduction venting the progression of chronic renal failure. Their mechanism of action is not clearly established. Several factors (growth hormone, insulin-like growth Methods. The effect of enalaprilat on hydrogen perox- factor-1, transforming growth factor-beta, tumour necide (H 2 O 2 ) production by cultured murine mesangial rosis factor-alpha, interleukin-1 and others) play a role cells exposed to 5.5 (basal condition), 30 and 50 mM in the damaging effects of hyperglycaemia in chronic glucose concentrations was examined over 8 h. A fluo- renal failure of diabetic nephropathy [1,2]. rimetric method quantifying, in arbitrary units, the Hydrogen peroxide (H 2 O 2 ) and other reactive intracellular dichlorofluorescein ( DCFH) oxidation to oxygen metabolites ( ROM) such as superoxide anion the highly fluorescent compound 2’7’dichlorofluoresc- and hydroxyl radical are also mediators of tissue injury ein (DCF ) from the non‐fluorescent probe dichloro- [3]. These reactive species are associated with both fluorescein-diacetate (DCFH-DA) was employed (a immune and non-immune glomerular injury [4,5], method not previously reported for cultured mesangial chronic progression of renal disease [5,6] and also with cells). Experiments were repeated three times in quad- diabetic vascular complications [3,7]. However, little ruplicate wells. information exists regarding a possible role of mesangResults. H 2 O 2 production by mesangial cells exposed ial cell in ROM production in diabetes mellitus. to 50 mM glucose was significantly increased after 1 Recently a significant lipid peroxide production in h, compared to cells exposed to 5.5 and 30 mM glucose. cultured rat glomeruli exposed to high glucose concenThis observation was not reproduced with 50 mM trations has been reported. The proposed biochemical mannitol. Addition of 100 ng/ml enalaprilat to cells pathway is a de novo synthesis of diacylglycerol with 50 mM glucose significantly inhibited H 2 O 2 pro- resulting from hyperglycaemia, leading to an activation duction during the 8 h of the assay. This response was of the protein kinase C ( PKC ) enzyme [8 ]. similar to that obtained with 100 ng/ml catalase. Angiotensin-converting enzyme (ACE ) inhibitors Increasing enalaprilat concentrations (10, 50 and are drugs with significant clinical benefits in the preven100 ng/ml ) also significantly decreased the constitutive tion of chronic renal failure in diabetic nephropathy H 2 O 2 generation in the presence of 5.5 mM glucose. [9]. The mechanism of renal protection, which appears not to be fully related to their hypotensive effect

Several studies have shown the participation of MMPs in oral squamous cell carcinoma, the most frequent malignant neoplasm of the oral cavity. The expression of some MMPs correlates with a more aggressive biological behaviour. The objective of this study was to determine which MMPs and TIMPs were expressed in both neoplastic and peritumoural stromal cells in different histopathology areas.Patients who underwent primary tumour neck dissection for oral squamous cell carcinoma were included. Immunoexpression of MMP-1, -2, -3, -7, -9, -11, -13, and TIMP-1 and -2 in different areas of pathologic specimens (in situ carcinoma, primary tumour, invasive front, distant invasion carcinoma, and lymph node metastasis) was evaluated. Enzyme expression on mucosa adjacent to tumour served as control.Thirty cases were included. Only 6 MMPs and 1 TIMP were expressed in the studied areas. Statistically significant differences in the number of cases with positive MMPs or TIMP expression, in both neoplastic and peritumoural cells, between control and the rest of the areas were observed. MMP-2 expression was constant in the areas with a more aggressive biological behaviour.MMP-2 expression may represent a dynamic interaction between host and tumour that favours the establishment of neoplastic cells at distant sites.

Azidothymidine (AZT) is an antiretroviral drug that affects cell proliferation, apoptosis, and the NF-κB pathway. As multiple myeloma (MM) presents with constitutive activation of NF-κB, we analyzed the effect of AZT on human MM cell lines. We evaluated the cytotoxic effect of AZT in human MM cell lines sensitive (8226/S) or resistant to doxorubicin (8226/DX5) and human T cell lymphoblast-like cells, uterine sarcoma cells, and HUVEC using MTT assay. Cytotoxicity was also evaluated in vivo in nude mice xenografted with 8226/S tumor. The effect of AZT on the expression of genes involved in cell proliferation, apoptosis, angiogenesis, and the NF-κB pathway was analyzed in the xenografts using real-time polymerase chain reaction. AZT was effective against both 8226/S and 8226/DX5 cells in a dose and time-dependent manner (p = 0.02) in vitro and promoted cell cycle arrest in S phase in these cells. The tumor volume was lower in mice treated with AZT compared to untreated mice (p = 0.0003). AZT down-regulated the pro-proliferative genes encoding AKT1, MYC, STAT1, MAPK8, MAPK9, CCL-3, Bcl-3, and cyclin D2; pro-angiogenenic genes encoding VEGF and IL8; and genes involved in cell adhesion (ICAM1 and FN1) and the NF-κB pathway. AZT up-regulated the expression of tumor suppressor gene FOXP1 and the pro-apoptotic genes encoding BID, Bcl-10, and caspase-8. Thus, we demonstrated the cytotoxic effect of AZT in human MM cell lines for the first time. Our data may provide the rationale for future clinical trials of AZT for treating MM.

The primary goal of this study was to characterize the existence of a functional c-di-GMP pathway in the bioleaching bacterium Acidithiobacillus ferrooxidans. A bioinformatic search revealed that the genome sequence of At. ferrooxidans ATCC 23270 codes for several proteins involved in the c-di-GMP pathway, including diguanylate cyclases (DGC), phosphodiesterases and PilZ effector proteins. Overexpression in Escherichia coli demonstrated that four At. ferrooxidans genes code for proteins containing GGDEF/EAL domains with functional DGC activity. MS/MS analysis allowed the identification of c-di-GMP in nucleotide preparations obtained from At. ferrooxidans cells. In addition, c-di-GMP levels in cells grown on the surface of solid energetic substrates such as sulfur prills or pyrite were higher than those measured in ferrous iron planktonic cells. At. ferrooxidans possesses a functional c-di-GMP pathway that could play a key role in At. ferrooxidans biofilm formation during bioleaching processes. This is the first global study about the c-di-GMP pathway in an acidophilic bacterium of great interest for the biomining industry. It opens a new way to explore the regulation of biofilm formation by biomining micro-organisms during the bioleaching process.

Metastases from infraclavicular neoplasms to the oral cavity are rare, and the anatomical structures most frequently affected are the maxillae. The primary sites that develop metastases to head and neck include lung, breast, liver, thyroid gland, kidney and melanomas, among others. The breast is one of the usual primary regions that can present them. In the literature, most metastases to these regions correspond to squamous cell carcinomas and adenocarcinomas; few studies report other type of neoplasms such as phyllodes tumour (PT) that present this behaviour. The importance of identifying metastatic disease to the oral cavity, be it as the first manifestation of a neoplasm from unknown origin or as a development in the course of the disease, is that it allows determination of adequate treatment, which has an effect on the patient's prognosis. The usual behaviour of PT is frequent recurrence and, when metastases are present, these are to lungs and bone. Two cases of malignant PT metastasising to tongue and lip are presented, as well as a review of the literature.

Eight U2 snRNA variants were isolated from several Bombyx mori U2-specific RT-PCR libraries. U2 sequences and secondary structures were generated and examined in terms of potential RNA and protein interactions. Analysis indicated that nucleotide changes occurred in both stem/loop and single-stranded areas. Changes in the double stranded areas were either compensatory, single substitutions (e.g. C--U) or prevented the double-stranded formation of one or two base pairs. The polymorphisms were clustered in moderately conserved regions. Some of the changes observed generated stronger base pairing. Inter-species conserved protein or RNA-binding sites were relatively unaffected. No polymorphic sites were found in known functional sequences. Bombyx mori and Drosophila melanogaster U2 sequences are 95% and 70% similar at the 5'- and the 3'-ends of the molecule, respectively. Phylogenetic analysis of the U2 sequences demonstrates remarkable conservation across species.

The objective of this work was evaluate risk factors for acquiring cutaneous leishmaniasis in Salta, the region with the greatest indices of transmission in Argentina. A Case-cohort study was realized from June 1989 to December 1992. The procedures performed on cases and controls included: a) socio-demographic questionnaire; b) domestic and peridomestic environment description; c) physical exam of skin and nasal and oral mucosal; d) Montenegro Skin Test. Multivariate analysis showed a significant risk for factors outside the home (cattle management, hunting, sleeping at the work place) and while at home (sleeping outside of the bedroom, presence of three or more pigs in the yard and windows that cannot be locked in the closed position). This association allowed the identification of risk factors linked to the transmission of leishmaniasis in the home for the first time in Salta (Argentina).

The execution of the Granada Metropolitan’s underground line made possible the discovery of archeological remains of a water tank in Alcázar Genil, a royal muslim residence of the 13th century. The water tank, 419 × 88 ft, was destroyed at its ends due to the growth of the city of Granada during the 20th century and today remains only its center section, under Camino de Ronda, exactly where the future Metropolitan will take place. The location of an underground station will allow the recovery, the integration and the exhibition of the archaeological remains of this water tank. The Alcázar Genil station project brings together the work of several disciplines which put in the same level engineering of the 13th and of the 20th century. These different teams work in an interdisciplinary approach to respond to the complexity of the entire project. The aim is to make contemporary infrastructures compatible with the past that is hidden under the skin of our historic centres., La ejecución del tramo subterráneo del metropolitano de Granada ha permitido el hallazgo de los restos arqueológicos de la alberca del Alcázar Genil, residencia regia musulmana periurbana del siglo XIII. El Albercón, de 128 × 27 metros, fue devorado en sus extremos durante el crecimiento urbano del siglo XX, salvándose el tramo central pisado por el Camino de Ronda, vial bajo cuyo trazado discurre el metropolitano. El emplazamiento en Alcázar Genil de una estación subterránea posibilitará la integración de los restos arqueológicos de la alberca, recuperándolos, poniéndolos en valor y haciéndolos visitables.El proyecto de la estación Alcázar Genil aúna los esfuerzos conjuntos de diversas disciplinas que ponen al mismo nivel las ingenierías de los siglos XIII y XXI con una visión interdisciplinar básica para abarcar la complejidad de todo el proyecto con el objetivo de compatibilizar las infraestructuras contemporáneas con el pasado oculto bajo la piel de nuestros viejos centros históricos.

In eukaryotes the enzyme 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase catalyses the synthesis of mevalonic acid, a common precursor to all isoprenoid compounds. Here we report the isolation and overexpression of the gene coding for HMG-CoA reductase from Leishmania major. The protein from Leishmania lacks the membrane domain characteristic of eukaryotic cells but exhibits sequence similarity with eukaryotic reductases. Highly purified protein was achieved by ammonium sulphate precipitation followed by chromatography on hydroxyapatite. Kinetic parameters were determined for the protozoan reductase, obtaining K(m) values for the overall reaction of 40.3+/-5.8 microM for (R,S)-HMG-CoA and 81.4+/-5.3 microM for NADPH; V(max) was 33.55+/-1.8 units x mg(-1). Gel-filtration experiments suggested an apparent molecular mass of 184 kDa with subunits of 46 kDa. Finally, in order to achieve a better understanding of the role of this enzyme in trypanosomatids, the effect of possible regulators of isoprenoid biosynthesis in cultured promastigote cells was studied. Neither mevalonic acid nor serum sterols appear to modulate enzyme activity whereas incubation with lovastatin results in significant increases in the amount of reductase protein. Western- and Northern-blot analyses indicate that this activation is apparently performed via post-transcriptional control.

This paper concerns the design, synthesis, and evaluation of inhibitors of leishmanial and trypanosomal dihydrofolate reductase. Initially study was made of the structures of the leishmanial and human enzyme active sites to see if there were significant differences which could be exploited for selective drug design. Then a series of compounds were synthesized based on 5-benzyl-2, 4-diaminopyrimidines. These compounds were assayed against the protozoan and human enzymes and showed selectivity for the protozoan enzymes. The structural data was then used to rationalize the enzyme assay data. Compounds were also tested against the clinically relevant forms of the intact parasite. Activity was seen against the trypanosomes for a number of compounds. The compounds were in general less active against Leishmania. This latter result may be due to uptake problems. Two of the compounds also showed some in vivo activity in a model of African trypanosomiasis.

Since 2006 projects have been carried out in the Universidad Nacional de Tucuman to introduce Telemedicine in the Provincial System of Health (SIPROSA) in Tucuman, Argentina. These projects aim at improving accessibility to remote populations, providing equity and avoiding costly and unnecessary transfers as well as helping early diagnosis and treatments, timely and appropriate referrals. On the other hand, this consultation has already been set up within the SIPROSA with the application of the system of reference and counter- reference for several years. By applying Telemedicine it is possible to accelerate the times and make this more efficient. This paper presents a prototype Web application for performing consultation in dermatology. These were conducted by professionals in Ranchillos, a small town within the Province, together with specialists from the capital city. After the experience, it can be said that the teledermatological application of the platform has been well received by physicians and dermatologists of rural areas, especially because the interfaces could be adjusted to their requirements. The physicians consider it a useful tool to complete the process of referral and counter-referral.

Escherichia vulneris is an enterobacteriaceae seldom isolated in microbiology laboratories. We report two cases of infection with positive cultures for this microorganism.Microbiological cultures of wound secretion and peritoneal fluid on usual media. Identification by PASCO and API 20E systems. Antimicrobial sensitivity was performed by a commercial microdilution system.The first case is a postsurgical hand infection from which was isolated Escherichia vulneris with Enterococcus faecium, it shows the typical presentation of infection by this bacteria. The second case consists of a peritonitis after aggressive abdominal surgery. In the peritoneal fluid culture, Escherichia vulneris and Cedecea neteri were recovered.The isolation of Escherichia vulneris has not been reported previously in Spain. We contribute towards its better knowledge with two clinical reports: a typical infection and an exceptional isolation from peritoneal fluid.

Endovenous rHu-EPO treatment by a constant and low dosage is as effective as in a variable and increasing way. We have seen an important differentiated effect on iron stores: Variable dosage may decrease iron stores whereas this is not seen in the former.

Some acridine compounds referred to as 9-imino, 9-oxo and 9-thio derivatives were screened for activity against Trypanosoma cruzi in vitro. The results are discussed here with refer

The emulsion copolymerization kinetics of styrene-butyl acrylate was studied in a batch process. The effect of the initiator, emulsifier, chain transfer agent and monomer concentration on copolymerization rate and molecular weight distribution is discussed. Thermal and viscoelastic properties of copolymers were measured. It was found that the n-dodecylthiol introduced into the reactor with the monomers did not affect the copolymerization rate (no redox reaction with the initiator) but the molecular weight was strongly dependent upon its concentration. These two kinetic parameters increase with increasing the butyl acrylate concentration.

In vitro antiamebic activity of selected acridine derivatives has been investigated against Naegleria and Acanthamoeba species. The most active compounds belong to the 9-thioacridanone and the 1,2,3,4-tetrahydro-9-thioacridanone series. In addition, some structure-activity relationships are proposed.

Dans ce travail nous etudions les modifications produites par trois enzymes proteolytiques, sur la penetration des formes metacycliques de Trypanosoma cruzi de culture dans des macrophages peritoneaux non stimules de souris. Les enzymes proteolytiques employees sont : trypsine, papaine et collagenase. Quand les formes metacycliques ou les macrophages sont pretraites avec les enzymes proteolytiques, le taux de penetration diminue, mais le phenomene n’est pas completement inhibe. De plus, nous observons que le nombre des parasites par cellule demeure stable au cours des experiences.

The synthesis and the antiparasitic evaluation of twelve new 5-nitroimidaole derivatives has been carried out. The most effective compounds were the less hydrophilic pyridinium and imidazolium salts (IV), (V) and (X), and above all the tetrahydropyridine derivatives (XII) and (XIII).

The trypanocidal activity of three new compounds derived of the antineoplastic drug cis-diamminodichloroplatinum(II) (DDP) has been studied over epimastigote forms of Trypanosoma cruzi. The electron microscopy indicated that, in the treated animals, the nuclear chromatin is distributed in the nucleus in a lax form and that the number of lipidic vacuoles increases largely. This action is more significant when cis-Pt(II)1,2-diaminocyclohexane is used. In addition this compound causes a destabilization of the DNA double helix with a decrease of melting temperature. The three compounds inhibit the incorporation of leucine, uridine and thymidine, although the thymidine uptake is the most significantly affected.

Extrachromosomal DNA elements have been identified in wild-type populations of the parasitic protozoan Leishmania. Elements from L. major and L. tropica were detected using orthogonal-field-alternation-gel electrophoresis. They are nonhomologous, supercoiled circular DNA molecules derived from different chromosomes in the Leishmania genome. Electron microscopy revealed that the elements have very similar physical properties; both are 80-kilobase supercoiled DNA molecules that contain large inverted repeat structures. The extrachromosomal DNAs are amplified in the Leishmania populations and show a fluctuation in copy number, from undetectable to around 20 copies per cell. After exposure of the L. tropica population to the drug methotrexate (MTX), a second amplified DNA was observed that is homologous to the extrachromosomal DNA found in L. major. Furthermore, wild-type Leishmania populations containing extrachromosomal DNA adapt more readily to MTX selection than populations with no amplified DNA. From these observations, there appears to be a relationship between the presence of extrachromosomal elements in wild-type Leishmania and the genesis and maintenance of MTX resistance in these organisms.

A method for the purification of metacyclic forms of Trypanosoma cruzi has been developed. Metacyclic forms obtained in modified Grace medium were separated from the epimastigote forms by Percoll discontinuous density gradient centrifugation. Four different osmotic pressures were applied: 160 +/- 10, 260 +/- 10, 310 +/- 10 and 510 +/- 10 mosmol/kg H2O. At 160 mosmol/kg H2O, 100% of the metacyclic forms with a 21.3% yield were found in the interphase 1.120/1.125 g/ml, while 92.7% of the metacyclic forms with a 73.7% yield were found in the interphase 1.115/1.120 g/ml. At 310 mosmol/kg H2O, 100% of the metacyclic forms in the interphase 1.135/1.140 g/ml with a 36.8% yield were obtained. Metacyclic forms purified in this way do not show alterations in their capacity to infect cultures of HeLa cells.

Osuna A. , Gamarro F. , Castanys S. and Ruiz-Perez L.M. 1986. Inhibition of lysosomal fusion by Trypanosoma cruzi in peritoneal macrophages. International Journal for Parasitology16: 629–632. Prelabelling of lysosomes with acridine orange has been performed in order to verify whether metacyclic forms of Trypanosoma cruzi are capable of inhibiting lysosomal fusion during the first moments of interiorization in non-sensitized mouse peritoneal macrophages. Thus, the degree of degranulation (lysosomal fusion) in metacyclic forms is low while epimastigote forms present higher levels. When epimastigote forms are made to interact with the macrophages in the presence of various concentrations of the medium used for transformations of epimastigotes to metacyclic forms or when interaction was performed in the presence of NH4Cl, the degree of degranulation was similar to that obtained when interaction was carried out with metacyclic forms. The present results suggest that during the first moments of the interaction of T. cruzi, only the infective forms may increase the cytoplasmic pH value of the host phagocytic cell, avoiding lysosomal fusion and the subsequent destruction of the parasite.

In vitro antiamebic activity of selected acridine derivatives has been investigated against Naegleria and Acanthamoeba species. The most active compounds belong to the 9-thioacridanone and the 1,2,3,4-tetrahydro-9-thioacridanone series. In addition, some structure-activity relationships are proposed.

A method is described for the isolation and purification of the intracellular amastigotes ofTrypanosoma cruzi from cultured Vero cells. Host cells were infected with metacyclic forms obtained in Grace's medium. Six days after infection, the cells were subjected to treatment with trypsin to obtain the intracellular forms. The parasites were collected and purified by Percoll discontinuous gradient centrifugation.

Results are presented on the effects of human lymphoblastoid interferon (HUIFN-α-ly) on the infectivity of metacyclic culture forms of Trypanosoma cruzi in HeLa cells. When cells were pretreated with interferon the parasitisation ratios of the cultures increased with respect to controls. This phenomenon also occurs when interferon was added during the period of parasite-cell interaction. When parasites were pretreated with interferon but cells were not, no increase in the parasitisation ratios was observed.

The percentage of parasitisation and index of adherence of Trypanosoma cruzi has been studied when host HeLa cells or metacyclic forms were pretreated with neuraminidase or with poly-L-lysine. The percentage of parasitisation was significatively reduced (P less than or equal to 0.001) when cells were pretreated with poly-L-lysine while pretreatment with neuraminidase caused no apparent effects. On the other hand, the adherence of the metacyclic forms pretreated with poly-L-lysine or neuraminidase was significantly higher than that of the control group.

Excerpt To the editor: We read with interest the report by Lakhanpal and associates (1) about transient regional osteoporosis. We agree with the clinical description of the syndrome, but wish to po...