Worldwide comparison between the potential distribution of Rhipicephalus microplus (Acari: Ixodidae) under climate change scenarios.

The cattle tick Rhipicephalus microplus (Acari: Ixodidae) has demonstrated its ability to increase its distribution raising spatially its importance as a vector for zoonotic hemotropic pathogens. In this study, a global ecological niche model of R. microplus was built in different scenarios using Representative Concentration Pathway (RCP), Socio-Economic Pathway (SSP), and a climatic dataset to determine where the species could establish itself and thus affect the variability in the presentation of the hemotropic diseases they transmit. America, Africa and Oceania showed a higher probability for the presence of R. microplus in contrast to some countries in Europe and Asia in the ecological niche for the current period (1970-2000), but with the climate change, there was an increase in the ratio between the geographic range preserved between the RCP and SSP scenarios obtaining the greatest gain in the interplay of RCP4.5-SSP245. Our results allow to determine future changes in the distribution of the cattle tick according to the increase in environmental temperature and socio-economic development influenced by human development activities and trends; this work explores the possibility of designing integral maps between the vector and specific diseases.

Exposure to progesterone before an ovulation synchronization protocol increases the follicular diameter and fertility of multiparous suckled Bos taurus cows.

The objective of this study was to evaluate the effect of administering injectable progesterone (P4i) before a timed artificial insemination (TAI) protocol on the follicular growth, ovulation, and pregnancy rate of Bos taurus suckled cows. The effect of P4i administration before the TAI on the pregnancy rate (P/AI) was evaluated in 576 suckled Bos taurus cows at 30-90 days postpartum. In addition, the effect of P4i administration before TAI on follicular dynamics was evaluated in subgroup of 401 suckled Bos taurus cows. On Day -10 (D-10), cows were divided into two experimental groups (Control and P4i). In this moment, P4i cows received i.m. 150 mg of injectable long-action progesterone. After that, both experimental groups received a synchronization protocol (Day 0; D0) that consisted of administration i.m. of 2 mg of estradiol benzoate and a progesterone intravaginal insert on D0. On Day 8 (D8), the progesterone insert was removed, and the cows received 500 µg of cloprostenol, 400 IU of eCG, and 1 mg of estradiol cypionate. TAI was performed 48 h after the removal of the progesterone insert. The ultrasound exams were performed in a subgroup of cows on Days 0, 8, 10 and 12 to evaluate the diameter of the largest follicle, rate of follicular growth and risks of single and double ovulation. The pregnancy diagnosis was performed 30 days after TAI in all cows to determine the pregnancy rate. The diameter of the largest follicle, on D10 (P = 0.84), rate of follicular growth (P = 0.14), ovulation rate (P = 0.40) and double ovulation rates (P = 0.23) did not differ between experimental groups. The pregnancy rate was greater in the P4i group [Control 46.2 % (133/288) vs. P4i 55.6 % (160/288); P = 0.03]. The diameter of the largest follicles (LF) on D0 (Control 11.6 ± 0.2 vs. P4i 13.3 ± 0.3) was greater (P = 0.01) in the P4i group. In conclusion, injectable progesterone before the ovulation synchronization protocol increased the diameter of the largest follicle on the D0 and the pregnancy rate in multiparous Bos taurus suckled beef cows.

Carbapenem-resistant Acinetobacter baumannii outbreak at university hospital.

Nineteen clonally related imipenem-resistant Acinetobacter baumannii isolates were recovered from eight intensive care unit patients. All isolates harboured bla OXA-51-like ß-lactamase genes and showed the absence of 22 kDa fraction in outer membrane porin profile analysis. It suggests a combination of two mechanisms as responsible for carbapenem-resistant phenotypes.

Intervenciones especializadas de enfermería en el cuidado de drenajes cerebrales / Specialized nursing interventions in the care of brain drains

Los drenajes cerebrales son dispositivos utilizados como métodos terapéuticos, permitiendo la salida de líquido normal o patológico a personas que cursen por alguna enfermedad neurológica, convirtiéndose en uno de los procedimientos más comunes en el área de la enfermería neurológica. He aquí que los cuidados de enfermería deben ser considerados específicos para poder visualizar resultados satisfactorios en pacientes portadores de estos sistemas en áreas críticas. Por este motivo, las intervenciones especializadas de enfermería en el cuidado a los drenajes cerebrales se basaron en la necesidad de elaborar una guía de intervenciones específicas, y especializadas, para personas con uso de drenajes cerebrales siendo un tema de importancia en enfermería neurológica.

Brain drains are devices used as therapeutic methods, allowing the exit of normal or pathological fluid to people suffering from a neurological disease, becoming one of the most common procedures in the area of neurological nursing. Here, nursing care must be considered specific in order to visualize satisfactory results in patients with these systems in critical areas. For this reason, specialized nursing interventions in the care of brain drains were based on the need to develop a guide for specific and specialized interventions for people with use of brain drains, being a topic of importance in neurological nursing.

Protein release from physically crosslinked hydrogels of the PLA/PEO/PLA triblock copolymer-type.

A series of PLA/PEO/PLA triblock copolymers was prepared by ring opening polymerization of rac-lactide in the presence of various di-hydroxyl poly (ethylene glycol)s, using CaH2 as a biocompatible initiator. Hydrogels were prepared by a phase separation method consisting of introducing small amounts of water over solutions of the copolymers in a biocompatible organic solvent, namely tetraglycol [poly(ethylene glycol monotetrahydrofurfuryl ether)]. The resulting hydrogels appeared much more hydrophilic than the rather tough hydrogels formed by swelling of dry tablets or films processed from the same copolymers. The phase separation-derived hydrogels were soft enough to be injected through a trochar. Two proteins, namely bovine serum albumine (BSA) and fibrinogen, were physically entrapped in these hydrogels by mixing with the polymer solutions before gel formation. This procedure appeared to be protein-respecting according to circular dichroism analysis on the released BSA. Dramatically different release profiles were obtained for the two proteins. In the case of BSA, the release depended on the quantity of protein incorporated in the hydrogel and presented a parabolic-type profile, in agreement with the behaviors of diffusion-controlled monolitic drug delivery devices. In contrast, almost linear release profiles were observed in the case of fibrinogen, the hydrogels behaving like a reservoir drug delivery system. These findings are tentatively interpreted in terms of gel-protein compatibility in the case of BSA and gel-protein incompatibility in the case of fibrinogen.

Clonal relationship among invasive and non-invasive strains of enteroinvasive Escherichia coli serogroups.

The genetic relatedness among 96 invasive Escherichia coli belonging to several serogroups and 13 non-invasive of several serotypes that share the same O antigen was investigated by multilocus enzyme electrophoresis analysis. The invasive strains were isolated in different parts of the world and most of them recovered from dysentery. Twenty-nine electrophoretic types were distinguished and the most invasive strains were found to belong to two major lineages. These results suggested that the invasive ability in these strains has evolved in divergent chromosomal backgrounds, presumably through the horizontal spread of plasmid-borne invasion genes. The maintenance of invasive phenotypes in separate lineages suggests that this ability confers a selective advantage to invasive strains.

Characterization of enteroinvasive Escherichia coli and Shigella strains by RAPD analysis.

Genetic variation of 33 enteroinvasive Escherichia coli (EIEC), 12 non-EIEC and 39 Shigella strains (representing the 4 species of this genus) was analyzed using the random amplified polymorphic DNA (RAPD) technique. Reproducible polymorphisms were generated and the combined data allowed us to construct a dendrogram using Jaccard's distance. Two main groups were obtained: one for Shigella and the other for EIEC and non-EIEC strains. The first group contained four clusters, one for each Shigella species. The second group contained one cluster for EIEC and another for non-EIEC strains. The main clusters encompassed many small clusters corresponding to different serotypes. It was possible to characterize each one of the 84 strains under study as well as the boundaries among Shigella species and between this genus and EIEC strains.

Altered response to thyroid hormones by prostate and breast cancer cells.

Transferrin, an abundant bone marrow constituent, has been shown to be a potent mitogen in vitro in the prostate cancer cell line PC3. T4 (L-thyroxine) and T3 (3',3,5-tri-iodo-L-thyronine) are regulators of cell metabolism. In this study, the effects of nonphysiological concentrations (about two orders of magnitude higher) of T4, T3, T2 (3,5-di-iodo-L-thyronine), RT3 (reverse T3, 3',5', 3-tri-iodo-L-thyronine) and transferrin (about three orders of magnitude lower) were tested on the prostate cancer cell lines PC3, DU145 and LNCaP, and the breast cancer cell line MCF-7. In PC3 cells, increased proliferation by transferrin could be reversed by the addition of T3 or T4. T4 decreased proliferation in all cell lines tested, while transferrin increased proliferation in PC3 cells only. T3 decreased proliferation in PC3, LNCaP and MCF-7 cells but had no effect on DU145 cells. T4 and T3 gave two-state behavior in LNCaP cells. These results were combined to determine the essential iodines which produced the observed proliferative effects. Cell lines responded differently to T4, T3, T2, RT3 and transferrin suggesting a specific interaction among the compounds tested and the different cell lines. Finally, regulation of gene expression was demonstrated using DU145 cells. Upregulation of c-fos mRNA was observed in cultures at early time-points in the presence of T4, transferrin or both. Decreased expression was observed at later time-points with no expression at 4 h. An explanation for these results may be a change in thyroid hormone receptor/ligand affinity. Thus, the interactions between thyroid hormones and cancer cells may be different from those between thyroid hormones and normal cells.

Steady-state enzyme kinetics in the Escherichia coli periplasm: a model of a whole cell biocatalyst.

This study provided analysis of in vivo enzyme kinetics in a model system which consisted of alkaline phosphatase in the periplasm of Escherichia coli. Modeling of complete substrate titration curves was achieved for a wide range of intraperiplasmic enzyme levels and outer membrane permeabilities. The results helped to identify the features most important to optimize in vivo reaction velocity. For many situations, a surprising finding was that maximum enzyme expression was not a major concern. For example, for moderate enzyme expression levels and moderate substrate levels (ca 0-5 mM), the limiting step for the enzyme in the periplasm was substrate (para-nitrophenylphosphate) diffusion through the outer membrane. In vivo reaction velocity was directly proportional to substrate concentration, outer membrane permeability, and the cell concentration. Velocity was also quite insensitive to a potent inhibitor of the enzyme. Even though diffusion-limited, periplasmic reaction velocity was quite sensitive to temperature, suggesting that the conformation of porin proteins in the E. coli outer membrane governed the average size of the pore. This model system therefore defined important features of bacterial whole cell biocatalyst design, which may also apply to other reactors using intact cells as catalysts.

Altered response to thyroid hormones by breast and ovarian cancer cells.

BACKGROUND: In this study, L-thyroxine (T4), 3',3,5-triiodo-L-thyronine (T3), 3,5-diiodo-L-thyronine (T2), reverse T3; 3',5',3-triiodo-L-thyronine (RT3) and transferrin were added to breast cancer cell lines Hs 578T, MDA-MB-231, MDA-MB-468, and T-47D and ovarian cancer cell line OVCAR-3 to test the response to cell proliferation. MATERIALS AND METHODS: Breast and ovarian cancer cell lines were placed in serum-free medium prior to addition of effector. Proliferation was determined by thymidine incorporation. For Northern analysis, RNA was isolated and c-fos, cjun and TIEG expression assessed. RESULTS: No compound provided uniform results across all cell lines. T2 inhibited proliferation in Hs 578T and MDA-MB-468, had no effect in MDA-MB-231 and OVCAR-3, and stimulated proliferation in T-47D cells. T3 inhibited proliferation in all cell lines except T-47D in which two-state behavior occurred, with increased proliferation at low concentrations (< or = 10(-6) M) and decreased proliferation at high concentrations (> or = 10(-5) M). RT3 inhibited proliferation in Hs 578T, MDA-MB-231, and T-47D but had no effect in MDA-MB-468 and OVCAR-3. T4 inhibited proliferation in Hs 578T, MDA-MB-231, and MDA-MB-468 and had two-state behavior in T-47D and OVCAR-3. Finally, transferrin increased proliferation only in OVCAR-3 cells. Protooncogene expression was increased by both transferrin and T4 in the cell lines tested. CONCLUSIONS: Correlation of iodines and proliferative responses were used to determine "essential" iodines necessary to produce the observed effect. Interaction between these cancer cells and non-physiological concentrations of thyroid hormone can be explained by thyroid hormone receptors with altered binding properties. Thus, interaction of thyroid hormones and cancer cells may differ from what occurs with normal cells.

[Bronchial-associated lymphoid tissue lymphoma]. / Linfoma de tejido linfoide asociado al bronquio (BALT).

Two cases of non-Hodgkin's endobronchial or bronchial-associated lymphoid tissue lymphoma are reported; such cases are either extremely rare or underestimated. We emphasize the need to perform endoscopic examination in patients with lymphoma and clinical findings that suggest bronchial disease.

[Mucocele of the frontal sinus simulating metastasis of follicular thyroid carcinoma in an 131I scan]. / Mucocele del seno frontal simulando metástasis de carcinoma folicular de tiroides en un rastreo con 131I.

The 131I scan is the preferred test in the follow-up of differentiated thyroid cancer patients although the many unusual circumstances of radioiodine uptake that can provide false positive results must be identified. We present the case of a woman who had undergone a thyroidectomy and was being treated for follicular carcinoma with an ablative dose os radioiodine whose pre- and post-treatment scans only revealed post-surgical residual thyroid tissues. A total body scan with 131I performed at one year demonstrated the success of the ablation. However, a left supra-orbital pathological deposit was observed during a subsequent routine 131I scan. The thyroglobulin serum level was below the sensitivity level for the assay (< 1 ng/ml) and the serum antibodies against thyroglobulin were not detected. A simple x-ray and bone scintigraphy were inconclusive. The CT and MRI revealed the presence of a mucocele in the left frontal sinus which was confirmed through histological examination. The possibility of a false positive results in an 131I scan must always be kept in mind, especially in the presence of atypical uptakes and undetectable thyroglobulin serum levels. As far as we know, only one similar case has been published previously.

The domain Archaea in human mucosal surfaces.

Archaea present distinct features from bacteria and eukaryotes, and thus constitute one of the branches of the phylogenetic tree of life. Members of this domain colonize distinct niches in the human body, arranged in complex communities, especially in the intestines and the oral cavity. The diversity of archaea within these niches is limited to a few phylotypes, constituted in particular by methane-producing archaeal organisms. Although they are possibly symbionts, methanogens may play a role in the establishment of mucosal diseases by favouring the growth of certain bacterial groups.

[Intratumoral versus subareolar injection in breast cancer sentinel lymph node biopsy. A case report]. / Inyección intratumoral versus subareolar en el diagnóstico de la biopsia del ganglio centinela, en el carcinoma de mama. A propósito de un caso.

The use of deep (intratumoral, peritumoral) and superficial (subdermal, subareolar) administration is recognized as valid in sentinel lymph node biopsy for breast cancer. Herein, we are presenting a clinical case in which a personalized methodology was a determining factor in axillary staging. Initially, the radiotracer was injected intratumorally guided by ultrasound. The ultrasound scan identified a previously unknown axillary lymphadenopathy, with focal cortical thickening, this being a non-specific ultrasound finding, but with possibility of biopsy. The lymphoscintigraphy did not show uptake in the mentioned node, hence, a second subareolar dose was administered. On this occasion, the lymphoscintigraphy detected drainage to the sentinel node, which was the only one positive for micrometastases.

Steady state enzyme velocities that are independent of [enzyme]: an important behavior in many membrane and particle-bound states.

The popular paradigm for biological education in kinetics involves descriptions that are appropriate for soluble enzymes. Derivations seldom present the assumptions on which the fundamental parameter of these kinetics, the site rate constant, is based. This omission can create difficulty for understanding situations where the assumptions are invalid. Membrane- and particle-bound enzymes systems provide several examples. In fact, biological organisms show macroscopic design and enzyme expression levels which suggest utilization of alternative kinetic mechanisms. The role of substrate affinity and enzyme inhibitors is greatly altered, with correlated impact on biomedical and biotechnological designs. Enzymes may perform functions such as isolation of cell contents from the environment, an action that is usually reserved for membranes. These properties can be mimicked but never perfectly replicated in purified systems. This presentation provides a description of some of these behaviors for membrane- or particle-bound enzymes, using an approach that is closely correlated with the manner in which steady state enzyme kinetics are typically presented.

Accurate kinetic modeling of alkaline phosphatase in the Escherichia coli periplasm: implications for enzyme properties and substrate diffusion.

Alkaline phosphatase in the periplasm of Escherichia coli presents many of the complex factors that may influence enzymes in vivo. These include an environment that contains a high enzyme concentration, is densely populated with other macromolecules, and is separated from other compartments by a partial diffusion barrier. A previous study provided a partial description of this situation and developed a model that utilized kinetic behavior to estimate the permeability of the outer membrane [Martinez, M. B., et al., (1992) Biochemistry 31, 11500]. This study extends that description to provide a complete model for the enzyme at all substrate levels. Some of the parameters needed for complete modeling include the following: outer membrane permeability to the substrate and product, catalytic efficiency of the enzyme, number of enzymes per cell, and effects of the reaction product (an inhibitor) on the enzyme. The theoretical model fit the data quite well over a wide range of values for each of these parameters. The best fit of theory with experimental data required that the rate constant for product escape from the periplasm was 4-fold greater than that for substrate entry. This correlated with the relative sizes of the substrate and product. The excellent fit of theory and results suggested that alkaline phosphatase and its substrate were unaffected by the solution conditions in the periplasm. That is, the catalytic parameters (kcat and KM), determined for the enzyme in dilute solution, appeared to be unchanged by the conditions in the periplasm. The major factor that altered the kinetic behavior was the combined effect of the permeability barrier and the dense population of enzyme molecules in the periplasm. Given the large impact of these parameters on reaction properties, the excellent fit of theory and results was striking. Overall, this study demonstrated that enzyme action in the complex biological environment can be accurately modeled, if all factors that influence enzyme behavior are known.

Reduced outer membrane permeability of Escherichia coli O157:H7: suggested role of modified outer membrane porins and theoretical function in resistance to antimicrobial agents.

Outer membrane permeability of Escherichia coli O157:H7 was determined by an in vivo kinetic model with the periplasmic enzyme alkaline phosphatase [Martinez et al. (1996) Biochemistry 35, 1179-1186]. p-Nitrophenyl phosphate (PNPP) substrate, added to intact bacteria, must diffuse through the outer membrane to reach the enzyme. At low substrate concentration the bacterium was in the perfectly reactive state where all molecules that entered the periplasm were captured and converted to product. Transmembrane diffusion was rate limiting, and the permeability of the outer membrane was determined from kinetic properties. The O157:H7 strain grown at 30 degrees C showed one-sixth the permeability of wild-type E. coli grown at 30 degrees C. Wild-type bacteria grown at >/=37 degrees C show a physiological response with a shift in expression of outer membrane porins that lowered permeability to PNPP by approximately 70%. The O157:H7 strain did not display this temperature-sensitive shift in permeability even though a change in porin expression could be visualized by staining intensity of Omp F and Omp C on acrylamide gels. Altered behavior of the O157:H7 membrane was also indicated by a several thousand-fold lower response to transformation relative to wild-type E. coli. Matrix-assisted laser desorption ionization time of flight mass spectrometry and electrospray ionization mass spectrometry confirmed the expression of the Omp F and Omp C variants that are unique to E. coli O157:H7. This reduced outer membrane permeability can contribute to enhanced resistance of O157:H7 to antimicrobial agents.

Kinetic properties of enzyme populations in vivo: alkaline phosphatase of the Escherichia coli periplasm.

Studies were conducted to determine the role that diffusion may play in the in vivo kinetics of the Escherichia coli periplasmic enzyme, alkaline phosphatase (AP, encoded by the gene pho A). Passive diffusion of solutes, from solution into the periplasm, is thought to occur mainly through porins in the outer membrane. The outer membrane therefore serves as a diffusion barrier separating a population of periplasmic enzymes from bulk substrate. E. coli strains containing a plasmid with the pho A gene linked to the lac promoter were used in this study in order to vary the amount of enzyme per cell. Alkaline phosphatase assays were conducted with intact cells, and the substrate concentration at half-maximum velocity (normally the Km for the enzyme) was determined as a function of enzyme concentration per cell. The results showed that diffusion of substrate to the enzyme caused as much as a 1000-fold change in this parameter, compared to that of purified enzyme. This suggested that diffusion was the rate-limiting step of the enzymatic reaction in these cells. In agreement with this type of reaction, Eadie-Hofstee and Lineweaver-Burk plots were not linear. At their extremes, these plots represented two types of kinetics. At high substrate concentration, equilibrium of substrate between bulk solution and the periplasm was achieved, and the kinetic properties conformed to Michaelis-Menten. At low substrate concentrations, there were a large number of free (unbound) enzymes, and each substrate molecule that entered the periplasm, through the diffusion barrier, resulted in product formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated function of blood clotting factor VIIa mutants that have enhanced affinity for membranes. Behavior in a diffusion-limited reaction.

Blood clotting factor VIIa is involved in the first step of the blood coagulation cascade, as a membrane-associated enzyme in complex with tissue factor (TF). Factor VIIa is also an important therapeutic agent for hemophilia where its function may include TF-independent as well as TF-dependent mechanisms. This study compared the activity of wild type factor VIIa (WT-VIIa) with that of a mutant with elevated affinity for membrane (P10Q/Q32E, QE-VIIa). Phospholipid and cell-based assays showed the mutant to have up to 40-fold higher function than WT-VIIa in both TF-dependent and TF-independent reactions. Tissue factor-dependent reactions displayed the maximum enhancement when binding had reached equilibrium in competition with another TF-binding protein. In liposome-based assays, the association rate of WT-VIIa with TF occurred at a physical maximum and could not be improved by site-directed mutagenesis. A practical consequence was identical function of WT-VIIa and QE-VIIa in assays that depended entirely on assembly kinetics. Thus, factor VIIa mutants provided unique reagents for probing the mechanism of factor VIIa action. They may also offer superior agents for therapy.