Interconsulta en maltrato infantojuvenil: Característica de la población con sospecha de maltrato infantojuvenil del Hospital de Pediatría Juan P. Garrahan / Consultation on child abuse: Characteristics of a population with a high level of suspicion of child abuse at Hospital de Pedatría Juan P. Garrahan

El maltrato infantojuvenil constituye un problema de salud pública, presenta consecuencias negativas en el adecuado desarrollo de los niños y adolescentes. Es consecuencia de una multiplicidad de factores individuales, sociales, psicológicos y culturales que puede incluso desembocar en la muerte del niño o adolescente. El objetivo fue realizar una descripción sociodemográfica e identificar posibles variables específicas de maltrato en la población que realizó alguna consulta al hospital y que fue derivada por el médico tratante al Consultorio Multidisciplinario de Protección Infantojuvenil (CMPIJ). Se trató de un estudio descriptivo, prospectivo de corte transversal, realizado entre julio de 2016 y mayo de 2017 en el Hospital de Pediatría Juan P. Garrahan. El criterio de inclusión fue la población que realizó alguna consulta al hospital, ya sea por sospecha de maltrato o por otros motivos y fue derivada por el médico tratante al CMPIJ. Se evaluaron 96 casos. el 67,7% de las sospechas fueron de abuso sexual infantil (ASI), el 22,9% de maltrato físico y el 9,4% de trastorno facticio aplicado a otro. En los casos de alta sospecha de ASI, el 75% de los pacientes eran de sexo femenino; en el 50% de los casos, el supuesto agresor era conviviente y el 50% de las madres refirió antecedentes de malos tratos en la infancia. En los casos de alta sospecha de maltrato físico, el 53% de los pacientes era de sexo masculino, en el 83,3% de los casos el supuesto agresor era conviviente y el 76,5% de las madres refirió antecedentes de malos tratos en infancia. Se concluye la importancia de contar con datos fidedignos en lo relativo al maltrato Infantojuvenil para permitir elaborar estrategias de prevención tanto a nivel asistencial como de Salud Pública (AU)

Child abuse is a public health problem with a negative impact on the adequate development of children and adolescents. It is a consequence of multiple individual, social, psychological, and cultural factors that may even result in the death of the child or adolescent. The aim of this study was to provide a sociodemographic description and to identify possible specific variables associated with abuse in the population that visited the hospital and was referred to the Multidisciplinary Child Protection Clinic (MDCPC). A prospective, descriptive, cross-sectional study was conducted between July 2016 and May 2017 at Hospital de Pediatría Juan P. Garrahan. The inclusion criterion was the population that visited the hospital, either for suspicion of abuse or for other reasons, who were referred to the MDCPC by the treating physician. Overall, 96 cases were evaluated; 67.7% of the suspicions were of childhood sexual abuse (CSA), 22.9% for child battering, and 9.4% for Munchausen syndrome by proxy. Among the cases with a high level of suspicion of CSA, 75% were female; in 50% of the cases the supposed aggressor lived in the household, and 50% of the mothers reported a history of child abuse. In the cases of a high level of suspicion of child battering, 53% of the patients were male, in 83.3% of the cases the aggressor was living in the household, and 76.5% of the mothers reported a history child abuse. In conclusion, trustworthy data on child abuse are necessary to develop prevention strategies at both the care and public health levels (AU)

Talleres de promoción de buenos tratos en un hospital de alta complejidad / Workshop to encourage good manners in a tertiary care hospital

En los últimos años hubo un incremento en las consultas por violencia familiar en el Hospital de Pediatría Juan P. Garrahan. Reconociendo este hecho como un problema de salud, se decidió implementar talleres en salas de espera con el objetivo de visibilizar este fenómeno. En los mismos se realizan actividades de sensibilización y concientización con pacientes y sus familias sobre los buenos tratos en la infancia y vínculos respetuosos en la pareja. Se pretende con este escrito relatar la experiencia de los talleres de promoción de buenos tratos, planteando el desafío de coordinar acciones que permitan visibilizar la problemática y actuar en consecuencia, fomentando la reflexión de los profesionales de la salud (AU)

Over the past years there has been an increase in consultations at Hospital de Pediatría Juan P. Garrahan because of family violence. As the entity is recognized as a health problem, workshops were implemented in the waiting rooms to visualize this phenomenon. During these workshops, activities of sensitization and awareness building were conducted with the patients and their families about good manners in childhood and respectful bonds in the couple. The aim of this report was to present our experience with the workshops of good manners considering the challenge of coordinating actions that allow visualization of the problem and act on it, encouraging reflections of the health care professionals (AU)

Quality management indicators for tissue banks: an operative model from the period of 2002-2007.

AIM: The purpose of this study was to determine a specific indicator model to evaluate the Quality Management System (QMS) in Tissue Banks (TB) for deceased and/or live donors. METHODS: Quantitative Indicators for Quality Management are considered for deceased donors as the origin of therapeutic tissues. A glossary of definitions was established (also applicable for tissues from live donors): Deceased Therapeutic Real Donors (DTRD), donors that were processed and at least 1 tissue was harvested for a therapeutic purpose; Deceased Effective Donors (DED), DTRD in which 1 or more tissues were validated, stored, and/or grafted; Processed Tissues (PT), number of tissues harvested from a DTRD, which were processed and counted as final product units; Validated Tissues (VT), number of tissues as final product units, which fulfilled quality criteria to be grafted; Grafted Tissues (GT), number of transplanted tissues for therapeutic purposes; and Grafted Patients (GP), number of patients who were grafted with validated tissues. MANAGEMENT QUANTITATIVE INDICATORS: Deceased donors were considered from 2002 to 2007. The total number of tissues was 15,363: Productivity Index (PI), PI = DED/DTRD; Processing Quality Rate (PQR), PQR = VT/PT%; Productivity Efficiency per Donor (PED), PED = VT/DED; Grafted Tissues Coefficient (GTC), GTC = GT/VT; and Grafted Patients Index per Donor (GID), GID = GP/DED. RESULTS: Results were as follows: PI = 0.80; PQR = 76%; PED = 30.99; GTC = 0.93; and GID = 4. In our study, 80% of DTRD produced VT (PI = 0.80), which represented 76% of PT (average, 31 final products per donor). Also, 93% of the VT were grafted with 5 patients grafted per donor. CONCLUSIONS: Defined variables resulted in useful tools to evaluate QMS in a TB.

Guidelines to implement quality management systems in microbiology laboratories for tissue banking.

Human tissues for implants are a biomedical product that is being used more frequently by many medical disciplines. There are infections in the patients related to the implanted tissues. The early detection of infections transmitted by blood and the microbiological study of tissues before their clinical use are strategies in tissue banks to prevent these situations. This work sought to contribute to establish the bases for the operation of a laboratory applied to the microbiological quality control of tissues. Based on classical microbiological principles, we defined the operation of microbiological control and tissues sterilization since 2003. We determine lists of acceptable microorganisms for every tissue, criteria for the interpretation of results, and a diagnostic algorithm of microbiological quality. We observed that the circumstances of donor death can be a determinant of the quality. The environment and the operator should be investigated as probable sources of contamination in outbreaks. The criteria of work based on a solid methodology must help to avoid the transmission of infections between donor and recipient. This is a critical point in the quality management of a tissue bank.

Three decades of the history of donation and transplantation in Uruguay.

AIM: The aim of this study was to analyze the evolution of the legal framework, health system of donation, and transplantation of cells, tissues, and organs, measured based on processes and rates from 1978 to 2008 in Uruguay. MATERIALS AND METHODS: We analyzed 3 decades (1978-1988/1989-1998/1999-2008) by the following evaluation: the legislation, donation and transplantation system, procurement, registration of pre-state of voluntary donations, actual donations and transplantation rates of solid organs (kidneys, heart, liver, and pancreas), and rates of donation and transplantation of tissues (corneal and laminar [skin, amniotic membrane, and fascialata]), of cardiovascular elements (valves and vases), and of ostearticular tissues (bones and tendons). RESULTS AND CONCLUSIONS: Uruguay has maintained continuous governmental politics in donation and transplantation. In the last decade the elaboration of a strategic plan by promoting Laws and Decrees of Encephalic Death, Presumed Donation and Security of Cells and Tissues, as well as the creation of the Unit Procurement, the registration of nonrelated donors for hematopoietic stem cells, and the re-engineering of tissue banking, has shown a significant increase in deceased donation and cadaveric transplantation, reaching the first highest overall donor rate in Latin America with 24/pmp multiorgan donors.

Uruguayan experience with cryopreserved arterial homografts.

INTRODUCTION: We analyzed the Uruguayan experience with cryopreserved arterial homografts. We studied 55 medical records in the period from June 9, 2000 to April 7, 2007, including 41 from males and 14 from females, ranging from 36-78 years of age. The clinical indications were as follows: Group 1, revascularization of infrainguinal atherosclerotic occlusive disease by bypass due to the lack of availability of a suitable vein (n = 35); Group 2, substitution of an infected prosthetic grafts (n = 15); and Group 3, arteriovenous fistula (AVF) after failure of previous prosthetic loops by repeated thrombosis and/or infection in the absence of a vein (n = 5). RESULTS: Among Group 1, primary and secondary patency rates were 61% and 71%, respectively at 1 year with 15 complications, 3 infections, 8 thromboses, 2 aneurysms, 1 homograft degradation, and 1 death related to surgery. Among Group 2, the primary and secondary patency rates were 71% and 79%, respectively, at 1 year with 6 patients experiencing complications. Group 3 did not have complications with a primary patency rate of 67% at 1 year. CONCLUSIONS: The use of cryopreserved arterial homografts is a valid, accessible, and safe alternative in complicated vascular situations. In our country, it is a technology to consider for patients with critical limb ischemia, when the risk of a major amputation is high and it is not possible to have a suitable vein or prosthetic bypass. It can be an excellent alternative for the substitution of infected synthetic bypasses, especially to substitute in situ for an infected aortic graft.

Burkholderia cenocepacia O antigen lipopolysaccharide prevents phagocytosis by macrophages and adhesion to epithelial cells.

Chronic respiratory infections by the Burkholderia cepacia complex (Bcc) are of great concern to patients with cystic fibrosis. Bcc isolates may survive intracellularly within amoebae, respiratory epithelial cells and macrophages. The molecular mechanisms facilitating colonization and pathogenesis remain unclear. Given the importance of bacterial adhesion to host surfaces in microbial pathogenesis, we investigated the role of the O antigen LPS in the interaction of Burkholderia cenocepacia, a member of the Bcc, with macrophages and epithelial cells. Our results demonstrated that the O antigen modulates phagocytosis but does not affect intracellular survival of B. cenocepacia. Internalization of strains that lack O antigen was significantly increased compared to that of their isogenic smooth counterparts. However, no differences between rough and smooth strains were found in their ability to delay phagosomal maturation. We also found that the O antigen interfered with the ability of B. cenocepacia to adhere to bronchial epithelial cells, suggesting that this polysaccharide may mask one or more bacterial surface adhesins.

Biosynthesis and structure of the Burkholderia cenocepacia K56-2 lipopolysaccharide core oligosaccharide: truncation of the core oligosaccharide leads to increased binding and sensitivity to polymyxin B.

Burkholderia cenocepacia is an opportunistic pathogen that displays a remarkably high resistance to antimicrobial peptides. We hypothesize that high resistance to antimicrobial peptides in these bacteria is because of the barrier properties of the outer membrane. Here we report the identification of genes for the biosynthesis of the core oligosaccharide (OS) moiety of the B. cenocepacia lipopolysaccharide. We constructed a panel of isogenic mutants with truncated core OS that facilitated functional gene assignments and the elucidation of the core OS structure in the prototypic strain K56-2. The core OS structure consists of three heptoses in the inner core region, 3-deoxy-d-manno-octulosonic acid, d-glycero-d-talo-octulosonic acid, and 4-amino-4-deoxy-l-arabinose linked to d-glycero-d-talo-octulosonic acid. Also, glucose is linked to heptose I, whereas heptose II carries a second glucose and a terminal heptose, which is the site of attachment of the O antigen. We established that the level of core truncation in the mutants was proportional to their increased in vitro sensitivity to polymyxin B (PmB). Binding assays using fluorescent 5-dimethylaminonaphthalene-1-sulfonyl-labeled PmB demonstrated a correlation between sensitivity and increased binding of PmB to intact cells. Also, the mutant producing a heptoseless core OS did not survive in macrophages as compared with the parental K56-2 strain. Together, our results demonstrate that a complete core OS is required for full PmB resistance in B. cenocepacia and that resistance is due, at least in part, to the ability of B. cenocepacia to prevent binding of the peptide to the bacterial cell envelope.

Interactions of Burkholderia cenocepacia and other Burkholderia cepacia complex bacteria with epithelial and phagocytic cells.

Burkholderia cenocepacia is a member of the B. cepacia complex (Bcc), a group of opportunistic bacteria that infect the airways of patients with cystic fibrosis (CF) and are extraordinarily resistant to almost all clinically useful antibiotics. Infections in CF patients with Bcc bacteria generally lead to a more rapid decline in lung function, and in some cases to the 'cepacia syndrome', a virtually deadly exacerbation of the lung infection with systemic manifestations. These characteristics of Bcc bacteria contribute to higher morbidity and mortality in infected CF patients. In the last 10 years considerable progress has been made in understanding the interactions between Bcc bacteria and mammalian host cells. Bcc isolates can survive either intracellularly within eukaryotic cells or extracellularly in host tissues. They survive within phagocytes and respiratory epithelial cells, and they have the ability to breach the respiratory epithelium layer. Survival and persistence of Bcc bacteria within host cells and tissues are believed to play a key role in pulmonary infection and to contribute to the persistent inflammation observed in patients with CF. This review summarizes recent findings concerning the interaction between Bcc bacteria and epithelial and phagocytic cells.

The impact of the International Atomic Energy Agency (IAEA) program on radiation and tissue banking in Uruguay: development of tissues quality control and quality management system in the National Multi-Tissue Bank of Uruguay.

BNOT was created and regulated in 1977 and started its operation in 1978 according to the Decree No. 86/1977. By the Decree 248/005 is transformed in the National Institute of Donation and Transplantation of Cells, Tissues and Organs (Instituto Nacional de Donación y Trasplante de Células, Tejidos y Organos--INDT). The organisation has been operating within the State University Medical School and the Public Health Secretary and it is the governmental organisation responsible for the regulation, policy and management of donation and transplantation in Uruguay. By the Decree 160/2006 is responsible for human cells and tissues regulation too. The participation of the INDT in the IAEA program facilitated the introduction of the radiation sterilisation technique for the first time in the country. The radiation sterilisation of tissues processed by INDT (ex BNOT), was initially carried out in the 60 Cobalt Industrial Plant in the National Atomic Energy Commission of Argentina and now is carried out in INDT, using a Gamma Cell 220 Excel, which was provided by the IAEA through the national project URU/7/005. The results of the implementation of tissues, quality control and quality management system, are showed.

Control of cryopreservation procedures on blood vessels using fiber x-ray diffraction.

AIM: We sought to determine variations in fiber organization at the molecular level using x-ray diffraction analyses on human blood vessel specimens after cryopreservation processes. MATERIALS AND METHODS: Diffractometric profiles were performed on aortic and carotid cryopreserved-thawed vessel samples (CVS) versus the same fresh vessel samples (FVS). X-ray diffraction was performed on vascular tissues from 17 cadaveric donors after informed consent. Measurements utilized a Seifert Scintag PAD-II powder diffractometer with CuK(a) radiation; lambda = 1.5418 A. Scans were evaluated in the 5 degrees to 60 degrees range in theta -2theta mode, in the 5 degrees to 60 degrees range in 2-theta, with steps 0.1 degrees and 10 seconds per step. Ten aortic and 8 carotid diffractometric profiles were analyzed, using differential planimetric surfaces measured under x-ray diffraction curve. Diffractographic profiles were analyzed according to intervals based upon the ages of the donors. An ordering profile coefficient (OPC) was obtained as the quotient between the differential planimetric surface (DPS) of FVS versus CVS vessel ordering diffraction. RESULTS: There was a decreased ordering profile according to age: older donors showed less ordering than younger ones. Clear peaks at d-spacing of 2.86 A and 2.15 A (2-theta = 31.3 degrees and 42.0 degrees , respectively) were always confirmed despite the different profiles of samples. OPC showed a higher ordering profile among the CVS than FVS: 70% aortas and 62.5% carotids. CONCLUSION: The cryopreserved-thawed procedure does not damage the fibrillar organization of vessels.

Burkholderia cenocepacia requires the RpoN sigma factor for biofilm formation and intracellular trafficking within macrophages.

Chronic respiratory infections by Burkholderia cenocepacia in cystic fibrosis patients are associated with increased morbidity and mortality, but virulence factors determining the persistence of the infection in the airways are not well characterized. Using a chronic pulmonary infection model, we previously identified an attenuated mutant with an insertion in a gene encoding an RpoN activator protein, suggesting that RpoN and/or components of the RpoN regulon play a role in B. cenocepacia virulence. In this study, we demonstrate that a functional rpoN gene is required for bacterial motility and biofilm formation in B. cenocepacia K56-2. Unlike other bacteria, RpoN does not control flagellar biosynthesis, as evidenced by the presence of flagella in the rpoN mutant. We also demonstrate that, in macrophages, the rpoN mutant is rapidly trafficked to lysosomes while intracellular wild-type B. cenocepacia localizes in bacterium-containing vacuoles that exhibit a pronounced delay in phagolysosomal fusion. Rapid trafficking to the lysosomes is also associated with the release of red fluorescent protein into the vacuolar lumen, indicating loss of bacterial cell envelope integrity. Although a role for RpoN in motility and biofilm formation has been previously established, this study is the first demonstration that the RpoN regulon in B. cenocepacia is involved in delaying phagolysosomal fusion, thereby prolonging bacterial intracellular survival within macrophages.

Distinct functional domains of the Salmonella enterica WbaP transferase that is involved in the initiation reaction for synthesis of the O antigen subunit.

WbaP is a membrane enzyme that initiates O antigen synthesis in Salmonella enterica by catalysing the transfer of galactose 1-phosphate (Gal-1-P) onto undecaprenyl phosphate (Und-P). WbaP possesses at least three predicted structural domains: an N-terminal region containing four transmembrane helices, a large central periplasmic loop, and a C-terminal domain containing the last transmembrane helix and a large cytoplasmic tail. In this work, we investigated the contribution of each region to WbaP function by constructing a series of mutant WbaP proteins and using them to complement O antigen synthesis in DeltawbaP mutants of S. enterica serovars Typhi and Typhimurium. Truncated forms of WbaP lacking the periplasmic loop exhibited altered chain-length distributions in O antigen polymerization, suggesting that this central domain is involved in modulating the chain-length distribution of the O polysaccharide. The N-terminal and periplasmic domains were dispensable for complementation of O antigen synthesis in vivo, suggesting that the C-terminal domain carries the sugar-phosphate transferase activity. However, despite the fact that they complemented the synthesis of O antigen in the DeltawbaP mutant in vivo, membrane extracts containing WbaP derivatives without the N-terminal domain failed to transfer radioactive Gal from UDP-Gal into a lipid-rich fraction. These results suggest that the N-terminal region of WbaP, which contains four transmembrane domains, is essential for the insertion or stability of the protein in the bacterial membrane. We propose that the domain structure of WbaP enables this protein not only to function in the transfer of Gal-1-P to Und-P but also to establish critical interactions with additional proteins required for the correct assembly of O antigen in S. enterica.

Cryografts implantation in human circulation would ensure a physiological transition in the arterial wall energetics, damping and wave reflection.

Each artery conduces blood (conduit function, CF) and smoothes out the pulsatility (buffering function, BF), while keeping its wall protected against the high oscillations of the pulse waves (damping function, xi). These functions depend on each segment viscoelasticity and capability to store and dissipate energy. When a graft/prosthesis is implanted, the physiological gradual transition in the viscoelasticity and functionality of adjacent arterial segments is disrupted. It remains to be elucidated if the cryografts would allow keeping the physiological biomechanical transition. The aim of this study was to evaluate the cryografts capability to reproduce the functional, energetic and reflection properties of patients' arteries and fresh homografts. Common carotid's pressure, diameter and wall-thickness were recorded in vivo (15 patients) and in vitro (15 cryografts and 15 fresh homografts from donors). Calculus: elastic (Epd) and viscous (Vpd) indexes, CF, BF, dissipated (WD) and stored (WPS) energy and xi. The graft-patient's artery matching was evaluated using the reflection coefficient (Gamma) and reflected power (WGamma). Cryografts did not show differences in Epd, Vpd, BF, CF, WD, WPS, and xi, in respect to fresh homografts and patients' arteries, ensuring a reduced Gamma and WGamma. Cryografts could be considered as alternatives in arterial reconstructions since they ensure the gradual transition of patients' arteries biomechanical and functional behavior.

[Vascular access for haemodyalisis. Comparative analysis of the mechanical behaviour of native vessels and prosthesis]. / Accesos vasculares para hemodialisis: analisis comparativo del comportamiento mecanico de vasos nati.

INTRODUCTION: The prosthesis nowadays used in the vascular access for haemodialysis have low patency rates, mainly due to the luminal obstruction, determined by the intimal hyperplasia. Several factors have been related to de development of intimal hyperplasia and graft failure. Among them are the differences in the biomechanical properties between the prosthesis and the native vessels. In the searching for vascular prosthesis that overcomes the limitations of the currently used, the cryopreserved vessels (cryografts) appear as an alternative of growing interest. However, it is unknown if the mechanical differences or mismatch between prosthesis and native vessels are lesser when using cryografts. OBJECTIVE: To characterize and compare the biomechanical behaviour of native vessels used in vascular access and cryografts. Additionally, segments of expanded polytetrafluoroethylene (ePTFE) were also evaluated, so as to evaluate the potential biomechanical advantages of the cryografts respect to synthetic prosthesis used in vascular access. METHODS: Segments from human humeral (n = 12), carotid (n = 12) and femoral (n = 12) arteries, and saphenous vein (n = 12), were obtained from 6 multiorgan donors. The humeral arteries were studied in fresh state. The other segments were divided into two groups, and 6 segments from each vessel were studied in fresh state, while the remaining 6 segments were evaluated after 30 days of criopreservation. For the mechanical evaluation the vascular segments and 6 segments of ePTFE were mounted in a circulation mock and submitted to haemodynamic conditions similar to those of the in vivo. Instantaneous pressure (Konigsberg) and diameter (Sonomicrometry) were measured and used to calculate the viscous and elastic indexes, the compliance, distensibility and characteristic impedance. For each mechanical parameter studied, the mismatch between the prosthesis and the native vessel was evaluated. RESULTS: The ePTFE was the prosthesis with the higher mechanical mismatch (p < 0.05). The venous and arterial cryografts showed the least mismatch with native veins and arteries, respectively. The prosthesis with the least mechanical mismatch was different, depending on the native vessel evaluated, and for a native vessel, on the parameter considered. CONCLUSION: The mechanical mismatch between the native vessel and the vascular prosthesis used in a vascular access could be reduced using cryografts.

Accesos vasculares para hemodiálisis: análisis comparativo del comportamiento mecánico de vasos nativos y prótesis / Vascular access for haemodyalisis. Comparative analysis of the mechanical vehaviour of native vessels and prosthesis

presentan elevadas tasas de falla por obstrucción luminal, secundaria a hiperplasia intimal. La generación de hiperplasia intimal y falla protésica se han vinculado, entre otros factores, con las diferencias biomecánicas entre las prótesis y los vasos nativos. En busca de prótesis que superen las limitaciones de las actuales, los vasos criopreservados (crioinjertos) son una alternativa de creciente interés. Sin embargo, se desconoce si las diferencias o desacoples mecánicos entre prótesis y vasos nativos son menores con los crioinjertos. Objetivo: Caracterizar y comparar el comportamiento biomecánico de vasos nativos utilizados en accesos vasculares y crioinjertos. Para analizar posibles ventajas biomecánicas de los crioinjertos en relación con la prótesis sintética más utilizada, se estudiaron segmentos de politetrafluoroetileno expandido (ePTFE). Métodos: Segmentos de arterias humeral (n = 12), carótida (n = 12) y femoral (n = 12), y vena safena (n = 12), fueron obtenidos de 6 donantes cadavéricos. Las arterias humerales se estudiaron en estado fresco. De los restantes vasos, 6 segmentos se evaluaron en estado fresco, y 6 luego de criopreservados durante 30 días. Para la evaluación biomecánica, los segmentos vasculares y 6 prótesis de ePTFE se montaron en un simulador circulatorio, y se sometieron a condiciones hemodinámicas similares a las de in vivo. Se midió presión (Konigsberg) y diámetro (sonomicrometría) instantáneo, y se calculó: el índice viscoso y elástico, la complacencia, distensibilidad e impedancia característica. Para cada parámetro, se cuantificó el desacople mecánico entre prótesis y vaso nativo. Resultados: El ePTFE presentó mayor desacople mecánico (p < 0,05). Los crioinjertos venosos y arteriales presentaron menor desacople mecánico con venas y arterias nativas, respectivamente. La prótesis con menor desacople mecánico fue diferente, dependiendo de parámetro biomecánico, y del vaso nativo considerado. Conclusión: El desacople mecánico con vasos nativos usados en accesos vasculares podría reducirse utilizando crioprótesis

Introduction: The prosthesis nowadays used in the vascular access for haemodialysis have low patency rates, mainly due to the luminal obstruction, determined by the intimal hyperplasia. Several factors have been related to de development of intimal hyperplasia and graft failure. Among them are the differences in the biomechanical properties between the prosthesis and the native vessels. In the searching for vascular prosthesis that overcome the limitations of the currently used, the cryopreserved vessels (cryografts) appear as an alternative of growing interest. However, it is unknown if the mechanical differences or mismatch between prosthesis and native vessels are lesser when using cryografts. Objective: To characterize and compare the biomechanical behaviour of native vessels used in vascular access and cryografts. Additionally, segments of expanded polytetrafluoroethylene (ePTFE) were also evaluated, so as to evaluate the potential biomechanical advantages of the cryografts respect to synthetic prosthesis used in vascular access. Methods: Segments from human humeral (n = 12), carotid (n = 12) and femoral (n = 12) arteries, and saphenous vein (n = 12), were obtained from 6 multiorgan donors. The humeral arteries were studied in fresh state. The other segments were divided into two groups, and 6 segments from each vessel were studied in fresh state, while the remaining 6 segments were evaluated after 30 days of criopreservation. For the mechanical evaluation the vascular segments and 6 segments of ePTFE were mounted in a circulation mock and submitted to haemodynamic conditions similar to those of in vivo. Instantaneous pressure (Konigsberg) and diameter (Sonomicrometry) were measured and used to calculate the viscous and elastic indexes, the compliance, distensibility and characteristic impedance. For each mechanical parameter studied, the mismatch between the prosthesis and the native vessel was evaluated. Results: The ePTFE was the prosthesis with the higher mechanical mismatch (p < 0.05). The venous and arterial cryografts showed the least mismatch with native veins and arteries, respectively. The prosthesis with the least mechanical mismatch was different, depending on the native vessel evaluated, and for a native vessel, on the parameter considered. Conclusion: The mechanical mismatch between the native vessel and the vascular prosthesis used in a vascular access could be reduced using cryografts

Pattern and process in Amazon tree turnover, 1976-2001.

Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests.

[Prevalence of Staphylococcus aureus among food handlers from a metropolitan university in Chile]. / Prevalencia de Staphylococcus aureus en manipuladores de alimentos de alimentos de una Universidad de la Región Metropolitana.

BACKGROUND: An important agent of food intoxication is Staphylococcus aureus, that is able to produce enterotoxins. AIM: To detect Staphylococcus aureus contamination in cafeteria food handlers of a Chilean University. SUBJECTS AND METHODS: Nose, throat, hands and nail samples from 87 food handlers were obtained for microbiological examination. RESULTS: Fifty seven subjects (65.5%) were carriers of Staphylococcus aureus. Enterotoxigenic Staphylococcus aureus was found in 36 subjects (41%). The most frequently found enterotoxin was type B (18 samples) followed by type D (12 samples). Men bad a higher frequency of contamination than women (83 and 57% of positive samples respectively). CONCLUSIONS: The frequency of Staphylococcus aureus contamination among food handlers is high and should prompt personal and environmental hygienic measures.