Ecology of fleas and their hosts in the trifinio of north-east Argentina: first detection of Rickettsia asembonensis in Ctenocephalides felis felis in Argentina.

Fleas are important in public health due to their role as parasites and vectors of pathogens, including Rickettsia. The aim of this study was to evaluate the diversity, abundance and prevalence of fleas and the presence of Rickettsia in the trifinio of north-east Argentina. Fleas from household and synanthropic animals were obtained from urban and periurban areas. They were taxonomically identified and samples of 227 fleas in 86 pools were analysed by polymerase chain reaction targeting the gltA and ompB genes of Rickettsia spp. The study revealed that Ctenocephalides felis felis was dominant on dogs, cats and opossums, with higher prevalence in the periurban area. The Shannon-Wiener and Morisita-Horn indices expressed differences in the diversity and similarity values of the absolute abundances of the species between the areas compared. DNA amplifications revealed 30.8% C. f. felis pools positive for Rickettsia spp. Phylogenetic analysis showed that the haplotype obtained was identical to Rickettsia asembonensis from Peru and Brazil. This is the first detection in Argentina of R. asembonensis that infects C. f. felis, and we emphasize the importance of conducting research from a 'One Health' perspective on the role of opossums and rodents in the integration of the transmission cycles of rickettsial bacteria.

First Evidence of Akodon-Borne Orthohantavirus in Northeastern Argentina.

Orthohantaviruses (genus Orthohantavirus, family Hantaviridae) are the etiologic agents of Hantavirus Pulmonary Syndrome in the Americas. In South America, orthohantaviruses are highly diverse and are hosted by sigmodontine rodents (subfamiliy Sigmodontinae, family Cricetidae), an also diverse group of rodents. The aims of this work were to (1) identify orthohantavirus hosts and (2) to study the spatial and temporal variations in the prevalence of infection and their associations with community, environmental and individual characteristics, in different environments of Misiones province, northeastern Argentina. Live-capture sessions were carried out during two years in different land uses, with a trapping effort of 31,653 trap nights. We captured 719 individuals from the species Akodon montensis, Rattus rattus, Mus musculus, Calomys tener, Thaptomys nigrita, Oligoryzomys nigripes, Euryoryzomys russatus, Oligoryzomys flavescens, Brucepattersonius sp., and Juliomys pictipes. Antibodies against orthohantavirus were detected in Akodon montensis in one natural protected and one periurban areas, and it was the most abundant species in almost every study sites. We observed the presence of spatial focality of orthohantavirus infection and a positive association with host abundance suggesting the existence of a threshold density. At the individual level, large, reproductively active, and male individuals were more likely to have antibodies against orthohantavirus. This is the first record of orthohantavirus infection in A. montensis in Argentina, which shows the importance of investigations about emerging diseases.

Entropic determination of the phase transition in a coevolving opinion-formation model.

We study an opinion formation model by the means of a coevolving complex network where the vertices represent the individuals, characterized by their evolving opinions, and the edges represent the interactions among them. The network adapts to the spreading of opinions in two ways: not only connected agents interact and eventually change their thinking but an agent may also rewire one of its links to a neighborhood holding the same opinion as his. The dynamics, based on a global majority rule, depends on an external parameter that controls the plasticity of the network. We show how the information entropy associated to the distribution of group sizes allows us to locate the phase transition between a phase of full consensus and another, where different opinions coexist. We also determine the minimum size of the most informative sampling. At the transition the distribution of the sizes of groups holding the same opinion is scale free.

Presencia de enfermedad coronaria obstructiva en pacientes con SPECT negativo sometidos a coronariografía por tomógrafo de 64 canales / Obstructive coronary artery disease in patients with negative SPECT undergoing coronary angiography with a 64-slice CT angiogram

Objective. To evaluate the presence of obstructive coronary artery disease (OCD) in patients with negative SPECT undergoing 64-slice coronary CT angiography. Material and methods. From July 2007 to January 2010, patients with negative SPECT undergoing CT angiography were assessed. We used a Philips Brilliance 64-slice CT scanner and low osmolality iodinated contrast. Coronary arteries were divided into 16 segments and the presence of OCD (lesion> 50 percent), non-obstructive coronary disease (lesions <50 percent), or absence of coronary disease were evaluated. Results. From a population of 447 patients undergoing coronary angiography, 52 patients with negative SPECT were included in the study. The mean age was 60 years, and 67 percent corresponded to female patients. We observed 13 patients (25 percent) with OCD. Percentages of arterial anomalies were as follows: 92 percent, anterior descending artery; 53.8 percent, right coronary artery; 46.1 percent, circumflex coronary artery; 23 percent, lateroventricular coronary artery; 15.3 percent, posterior descending coronary artery; 7.7 percent, diagonal coronary artery. No lesion was found in the left coronary artery. Conclusion In our analysis, 25 percent of patients with negative SPECT showed significant obstructive lesions.

Objetivo. Evaluar la presencia de enfermedad coronaria obstructiva (ECO) en pacientes con SPECT negativo sometidos a Coronariografía TC64. Material y métodos. Se evaluaron pacientes sometidos a coronariografía TC con SPECT negativo desde julio 2007 a enero 2010.Se utilizó un tomógrafo Philips Brilliance 64 y contraste iodado de baja osmolaridad. Las arterias coronarias se dividieron en 16 segmentos evaluando la presencia de ECO (lesión > 50 por ciento), enfermedad coronaria no obstructiva (lesión < 50 por ciento) o sin enfermedad coronaria. Resultados. Del total de 447 pacientes, se incluyeron 52 pacientes con SPECT negativo. La edad media fue 60 años, 67 por ciento mujeres. Se observaron 13 pacientes (25 por ciento) con ECO. Las afecciones arteriales fueron: arteria descendente anterior en el 92 por ciento, coronaria derecha 53,8 por ciento, circunfleja 46,1 por ciento, lateroventricular 23 por ciento, descendente posterior 15,3 por ciento, diagonal 7,7 por ciento y ninguna en el tronco coronario izquierdo. Conclusión. Según nuestra serie, el 25 por ciento de los pacientes con SPECT negativo presentó lesiones obstructivas significativas.

[Hight resoluton optical microscopy of the cellular cycle in psoriasis patients]. / Estudio con microscopia optica de alta resolucion (MOAR) del ciclo celular en pacientes con psoriasis.

Skin tissue from patients with Psoriasis was analyzed using HROM (High Resolution Optical Microscopy), studying epithelial differentiation and possible structural alterations of the queratinocytes. The samples were taken from 10 patients with histopathologic diagnosis of Psoriasis. This tissue samples where affixed with glutaraldehide buffer-collidine for 48 hours. Later processed with the HROM technique and colored with toluidine blue, metilene blue, basic Fuscine, and silver metenamine. The basal epithelial elements presented ovoid nucleus and most of them had prominent nucleolus. In 7 of the studied cases, the granulose stratus was absent, and thinner in the rest, with nucleus and nucleolus retention. At this level queratinocytes where observed with perinuclear anfofilia, as well as linfocitic and macrophagic infiltrate and union complex where elongated.

Estudio con microscopia optica de alta resolucion (MOAR) del ciclo celular en pacientes con psoriasis / Hight resoluton optical microscopy of the cellular cycle in psoriasis patients

La Psoriais se caracteriza por incremento del ciclo celular a nivel epidérmico, evidenciado a nivel histopatológico por un intensa hiperparaqueratosis, acantosis, papilomatosis e inflamación crónica. Materiales y métodos: Se estudió con microscopia óptica de alta resolución (MOAR), la epidermis de pacientes portadores de Psoriasis, analizando, la diferenciación epitelial y las posibelas alteraciones estructurales de los queratinocitos. Resultados: Los especímenes correspondieron a 10 pacientes con diagnóstico clínico e histopatológico de psoriasis. Las biopsias de piel fueron fijadas en solución de glutaraldehido buffer-collidina durante 48hs, procesados con la técnica para MOAR y coloreados con azul de toluidina, azul de metileno, fuscina básica y metenamina-plata. Los elementos epiteliales basales presentaban núcleos ovoideos, varios de ellos con nucleólos prominentes. En 7 de los casos estudiados el estrato granuloso estuvo ausente y en los 3 casos restantes observamos retención de núcleos y nucleólos. Conclusiones: Seobservaron queratinocitos con anfofilia e infiltrado linfocitario y de macrofagos.

Skin tissue from patients with Psoriasis was analyzed using HROM (High Resolution Optical Microscopy), studying epithelial differentiation and possible structural alterations of the queratinocytes. The samples were taken from 10 patients with histopathologic diagnosis of Psoriasis. This tissue samples where affixed with glutaraldehide buffer-collidine for 48 hours. Later processed with the HROM technique and colored with toluidine blue, metilene blue, basic Fuscine, and silver metenamine. The basal epithelial elements presented ovoid nucleus and most of them had prominent nucleolus. In 7 of the studied cases, the granulose stratus was absent, and thinner in the rest, with nucleus and nucleolus retention. At this level queratinocytes where observed with perinuclear anfofilia, as well as linfocitic and macrophagic infiltrate and union complex where elongated.

Vascular endothelium express CS-1 fibronectin in allergic contact dermatitis.

BACKGROUND: Allergic contact dermatitis (ACD) is a common human dermatosis in which not all the mechanisms involved in its pathogenesis have been elucidated. OBJECTIVE: To study the expression of CS-1 fibronectin, TARC and Th1-associated chemokine receptors in biopsies from allergic patch test reactions. MATERIAL AND METHODS: Thirteen patients already diagnosed with ACD were challenged on the back with the antigen responsible of the disease and macroscopic responses and biopsies taken after 48 h. Skin biopsies from negative control challenge sites, AD and ICD were also taken. Samples were fixed, embedded in paraffin wax and processed in order to perform histological and immunohistochemical studies. RESULTS: All subjects with ACD showed a positive clinical response and a perivascular mononuclear cell infiltration at 48 h, which was not seen in the negative controls. The majority of skin-infiltrating cells were CD4+ and CD8+ and up to 54% or 40% of them expressed CXCR3 or CCR5, respectively. We also showed expression of CS-1 fibronectin in inflamed endothelial cells not only in ACD but also in AC and ICD. In contrast TARC was only expressed in ACD and AC. CONCLUSION: We showed for the first time that CS-1 fibronectin is expressed in dermal vessels from allergic patch tests positive reactions, as well as irritant and atopic skin lesions.

Thermal treatment of the minority game.

We study a cost function for the aggregate behavior of all the agents involved in the minority game (MG) or the bar attendance model (BAM). The cost function allows us to define a deterministic, synchronous dynamic that yields results that have the main relevant features than those of the probabilistic, sequential dynamics used for the MG or the BAM. We define a temperature through a Langevin approach in terms of the fluctuations of the average attendance. We prove that the cost function is an extensive quantity that can play the role of an internal energy of the many-agent system while the temperature so defined is an intensive parameter. We compare the results of the thermal perturbation to the deterministic dynamics and prove that they agree with those obtained with the MG or BAM in the limit of very low temperature.

Dynamical quenching and annealing in self-organization multiagent models.

We study the dynamics of a generalized minority game (GMG) and of the bar attendance model (BAM) in which a number of agents self-organize to match an attendance that is fixed externally as a control parameter. We compare the usual dynamics used for the minority game with one for the BAM that makes a better use of the available information. We study the asymptotic states reached in both frameworks. We show that states that can be assimilated to either thermodynamic equilibrium or quenched configurations can appear in both models, but with different settings. We discuss the relevance of the parameter G that measures the value of the prize for winning in units of the fine for losing. We also provide an annealing protocol by which the quenched configurations of the GMG can progressively be modified to reach an asymptotic equilibrium state that coincides with the one obtained with the BAM.

[Marjolin ulcer]. / Ulcera de Marjolin.

Marjolin's ulcers can produce neoplasms. They appear on previous scars produced by old three degree burns. Sometimes they appear after 50 years of the previous accident. Three patients showing squamous cell epitheliomas are presented, and the opportunity and technique of the surgical treatment is discussed.

Ulcera de Marjolin. / [Marjolin ulcer]

Marjolins ulcers can produce neoplasms. They appear on previous scars produced by old three degree burns. Sometimes they appear after 50 years of the previous accident. Three patients showing squamous cell epitheliomas are presented, and the opportunity and technique of the surgical treatment is discussed.

New superhard phases for three-dimensional C60-based fullerites

We have explored new possible phases of 3D C60-based fullerites using semiempirical potentials and ab initio density functional methods. We have found three closely related structures-two body-centered orthorhombic and one body-centered cubic-having 52, 56, and 60 tetracoordinated atoms per molecule. These 3D polymers result in semiconductors with bulk moduli near 300 GPa, and shear moduli around 240 GPa, which make them good candidates for new low density superhard materials.

Failure to detect unique reactivity to streptococcal streptokinase in either the sera or renal biopsy specimens of patients with acute poststreptococcal glomerulonephritis.

Using purified group A streptokinase (SKA) as the antigen, ELISA assays were carried out on the sera of normal unaffected children, acute poststreptococcal glomerulonephritis patients (APSGN) and acute rheumatic fever patients (ARF). The results demonstrate that antibody titers to SKA increase with age in normal children and by age 8 years the vast majority of children have antibodies to SKA. APSGN patients did not demonstrate unique reactivity to SKA when compared to ARF patients either at time of onset of disease or during convalescence. Polyclonal and monoclonal antibodies to SKA which recognize both group A and C streptokinase failed to detect the presence of streptokinase in the biopsy sections obtained from ten well-documented APSGN patients. We conclude that there is no unique reactivity to group A streptokinase in the sera of APSGN patients. Furthermore, we failed to demonstrate the presence of streptokinase in the biopsy specimens of an early case of APSGN patients.

Utilidad de la talidomina en el tratamiento del L. E. S / Usefulness of the thalidomine in treatment of SLE

Se presentan 13 caso de LES tratados exclusivamente con talidomida o con asociación tali-corticoidea. La evolución de estos casos, a fin de evaluar la acción medicamentosa, fue comparada con un lote testigo de 8 casos tratados también en el Servicio de Dermatología por LES, con tratamiento convencional. También se comparó la evolución post-terapéutica con lotes testigos provenientes de Clínica Médica (6 casos) y Nefrología (13 casos). Se consideró que los enfermos evolucionaron favorablemente cuando se observó mejoría clínica subjetiva del enfermo, mejoría en análisis de laboratorio de rutina y en exámenes inmunológicos. De los 40 casos, se observó evolución favorable en 15. De ellos, 8 (53%) habían sido tratados con talidomida en forma exclusiva (5 casos, 33%) o tratamiento talidocorticoideo (3 enfermos, 20%). Los otros 7 habían sido medicados con tratamiento convencional. Se observó que al asociarse talidomida al tratamiento corticoideo, la evolución favorable y la disminución de la dosis corticoidea era más rápida que con tratamiento convencional sin talidomida. También se observó que pasado el período de "poissé" podía retirarse totalmente el corticoide para continuar el tratamiento en período de acalmiaexclusivamente con talidomida. Pudo comprobarse que la suspensión de la talidomida, que por meses o años había mantenido al paciente sin sintomatología visceral, en varios casos fue seguida de agravamiento (4 casos) que en 2 terminó en el óbito

Un caso de melanodermia con componente amiloidotico / A case of melanodermia and amyloidosis

1. Se presenta un caso de melanodermia con componente amiloidótico en una paciente de sexo femenino, de 34 años de edad. Se hace el diagnóstico clínico por la morfología y la topografía, sumado al prurito persistente crónico y la evolución de las lesiones. 2. El laboratório no arroja datos de interés, salvo linfocitos reactivos. 3. El estudio histopatológico de varias tomas biopsias coloreadas con hematoxilina/eosina, con coloración de Rojo Congo y cristales de polarización, en presencia de un testigo (ganglio linfático de una amiloidosis secundaria) mostraron una refrigencia verdosa característica del amiloide, confirmando el diagnóstico de amiloidose cutánea. 4. Los estudios de inmunofluorescencia indirecta con Gamma total, IgM y C3, fueron negativos. 5. El estudio ultraestructural que consideramos como único específico y patognomónico, demostó las características fibrillas de amiloide. Los islotes se encontraron en dermis papilar, en capa basal y en el citoplasma de los queratinocitos con proximidad al núcleo. 6. El tratamiento general antihistamínico prolongado y el local corticoideo mantienen a la paciente en estado estacionario