Synergies, radiation and kinetics in photo-Fenton process with UVA-LEDs.

The photo-Fenton process, with UV-A LED (λ = 380-390, 390-400 and 380-400 nm) has demonstrated to be effective in the abatement of a target micropollutant, such as diphenhydramine hydrochloride (DPH). Different concentrations of iron (Fe2+) and H2O2 were tested and monitored, and the best results in DPH removal were obtained for the highest concentrations of both iron (II) and H2O2 (10 mg Fe2+/L - 150 mg H2O2/L). The evolution of iron and peroxide concentration was also monitored. Kinetic studies showed that dark Fenton process prevails at the beginning of the experiment, when Fe2+ concentration is higher. However, after these initial moments, the prevailing process is photo-Fenton and, in addition, wavelength radiation plays an important role. Concerning the effect of radiation, four LEDs (4.2 W total power) were used, emitting radiation in the wavelength range between 380-390 or 390-400 nm. Similar results were obtained in both cases in DPH removal by photo-Fenton (30 min for total elimination). However, a synergistic effect was observed when two LEDs of 380-390 nm and two LEDs of 390-400 nm were used. Total power was the same (4.2 W) in each experimental condition, but the increase in the wavelength range to 20 nm (380-400 nm) produces an increase in the rate of DPH removal, achieving its total elimination at 15 min. This fact, with the use of a simple radiation model, reveals the important role that radiation plays in the photo-Fenton process. Finally, the formed intermediates were determined and some reaction pathways were proposed.

First isolation and molecular characterization of Ehrlichia canis in Costa Rica, Central America.

The present study investigated Ehrlichia species in blood samples from dogs suspected of clinical ehrlichiosis, using molecular and isolation techniques in cell culture. From a total of 310 canine blood samples analyzed by 16S rRNA nested PCR, 148 (47.7%) were positive for Ehrlichia canis. DNA from Ehrlichia chaffeensis or Ehrlichia ewingii was not detected in any sample using species-specific primers in separated reactions. Leukocytes from five PCR-positive dogs were inoculated into DH82 cells; successful isolation of E. canis was obtained in four samples. Partial sequence of the dsb gene of eight canine blood samples (including the five samples for in vitro isolation) was obtained by PCR and their analyses through BLAST showed 100% of identity with the corresponding sequence of E. canis in GenBank. This study represents the first molecular diagnosis, isolation, and molecular characterization of E. canis in dogs from Costa Rica.

A Rac-Pak signaling pathway is essential for ErbB2-mediated transformation of human breast epithelial cancer cells.

The activation of receptor tyrosine kinases, particularly ErbB2, has an important role in the genesis of breast cancer. ErbB2 kinase activity promotes Ras-mediated stimulation of downstream protein kinase cascades, including the Ras/Raf-1/MAPK/ERK kinase (Mek)/extracellular signal-regulated kinase (Erk) pathway, leading to tumor cell growth and migration. Signaling through the Ras-Erk pathway can be influenced by p21-activated kinase-1 (Pak1), an effector of the Rho family GTPases Rac and Cdc42. In this study, we asked if ErbB2 expression correlates with Pak1 and Erk activity in human breast cancer specimens, and if Pak1 signaling is required for ErbB2 transformation in a three-dimensional (3D) in vitro setting and in xenografts. We found a correlation between ErbB2 expression and activation of Pak in estrogen receptor-positive human breast tumor samples and observed that in 3D cultures, activation of Rac-Pak1 pathway by ErbB2 homodimers induced growth factor-independent proliferation and promoted disruption of 3D mammary acinar-like structures through activation of the Erk and Akt pathways. Further, we found that inhibition of Pak1 by small molecules compromised activation of Erk and Akt, resulting in reversion of the malignant phenotype and restoration of normal acinar architecture. Finally, ErbB2-amplified breast cancer cells expressing a specific Pak inhibitor showed delayed tumor formation and downregulation of Erk and Akt signaling in vivo. These data imply that the Rac-Pak pathway is vital to ErbB2-mediated transformation and that Pak inhibitors represent plausible drug targets in breast cancers in which ErbB2 signaling is activated.

[Characterization of Haemophilus influenzae strains using sugar fermentation]. / Caracterización de cepas de Haemophilus influenzae mediante fermentación de azúcares.

64 Haemophilus influenzae strains circulating in Havana City during a year were characterized by the carbohydrate fermentation method for the first time in Cuba. The fermentative pattern D was the most frequently found. Patterns D and G together were 72% of the total of strains studied. The combination of the carbohydrate fermentation with serotyping and biotyping allowed a greater differentiation of strains (14 groups). Patterns A, B, C and F appeared in children over 6 months of age, and pattern G in the group from 6 to 18. Patterns D and G predominated in the bacterial meningoencephalitis. A higher heterogeneity was observed among the strains isolated from acute respiratory infections. Some of the advantages of the Haemophilus influenzae strains subtyping method are stressed, such as: simplicity, easiness to be applied and interpreted, and the fact that it is not necessary a qualified personnel or a specialized laboratory for its implementation.

[Utilization of different microbiological markers in the study of Haemophilus influenzae]. / Utilización de diferentes marcadores microbiológicos en el estudio de Haemophilus influenzae.

The present study includes 178 Haemophilus influenzae strains isolated in different pediatric hospitals from Havana, Cuba, during 1991-1994, associated to divers infections (meningitis, respiratory sepsis, primary bacteremia). A combination of various typing and subtyping methods was used as epidemiological markers: serotyping (slide agglutination with diagnostical serum a-f and latex agglutination), biotyping according to Killian's procedures (by determination of indole production, urease and ornithine decarboxylase activity), subtyping by fermentative profiles according to Roberts' methods (glucose, maltose, xylose and fructose) and outer membrane protein profile subtyping (vesicles extraction by a modified Barenkamp's method, analysis by lineal and gradient SDS-PAGE and assessment according to our own classification system). Serotype b was identified in 89.3%, biotype I was the most frequent (79.1%), other biotypes (II, III, IV and V) were also identified. Fermentative profile D (glucose, maltose, xylose and fructose positive) was the most frequent (52.8%) while profile G (glucose, maltose, xylose positive and fructose negative) represented 20.2%. Other known profiles were present. PA2 (33.7%) was the most frequent OMP subtype. Even though 11 different protein subtypes were found, the 77.5% of the strains were located in only three OMP electrophoretic subtypes (PA2, PC1, LA2).

[Microbiologic aspects of bacteremia in patients hospitalized in the intensive care unit]. / Aspectos microbiologicos de la bacteriemia en pacientes ingresados en la Unidad de Cuidados Intensivos.

The microbiologic aspects of the bacteriemia were prospectively studied in patients hospitalized in a pediatric Intensive Care Unit. Thirty six episodes of bacteriemia were detected in 29 patients. Secondary bacteriemia prevailed on the primary ones. The most frequent infectious foci associated with bacteriemia were the infections of respiratory tract, followed by intravascular catheterism. The microorganisms more frequently associated with bacteriemia were: Haemophilus influenzae, Staphylococcus epidermidis, Eacherichia coli and Pseudomonas seruginosa.

[Identification of non-fermenting gram-negative bacteria. "Havana Center" Pediatric Teaching Hospital. December 1986 through May 1987]. / Identificación de bacterias gramnegativas no fermentadoras. Hospital Pediátrico Docente "Centro Habana". Diciembre de 1986 a mayo de 1987.

A study is made of non-fermenting gram-negative bacterial strains isolated at the Microbiology Lab, "Centro Habana" Pediatric Teaching Hospital. The strains studied come from various types of samples with prevalence of exudates and smears. A definite biotyping of 100% of strains is made. 90.0% are classified within the genus Pseudomonas. In addition, organisms of the genera Acinetobacter, Alcaligenes, Achromobacter, and Moraxella are identified. The most frequent species turned out to be Pseudomonas aeruginosa, which accounted for 68.4% of the total.

[Introduction of King A and King B media for the diagnosis of Pseudomonas aeruginosa at the Teaching Pediatric Hospital of Centro Habana]. / Introducción de los medios King A y King B para el diagnóstico de Pseudomonas aeruginosa en el Hospital Pediátrico Docente de Centro Habana.

The use of King A and King B media for the faster diagnosis of Pseudomonas aeruginosa is introduced in the Microbiology Laboratory of Centro Habana Pediatric Teaching Hospital. The appropriate use of these media allows to classify as Pseudomonas aeruginosa 77.2% of the Pseudomonas sp. strains studied, which represent 95.2% of the total of strains identified as Pseudomonas aeruginosa, according to Hugh and Gilardi conventional technique. There are no significant differences in the implementation of the two procedures (X2: 0.5; p less than 0.05). The demonstrations of pyocines with King A medium is significantly superior to the method for extraction and solubility of the pigment in chloroform (X2: 15.05; p less than 0.01).