Long-term results with biosynthetic absorbable P4HB mesh in ventral abdominal wall repair: a multicentre analysis.

BACKGROUND: The aim of this multicentre study was to analyse the outcomes of biosynthetic absorbable poly-4-hydroxybutyrate (P4HB) prosthesis implantation in patients undergoing ventral hernia repair (VHR) in the context of different degrees of contamination. METHODS: From May 2016 to December 2021, a multicentre retrospective analysis of patients who underwent elective or urgent hernia repair with P4HB prosthesis was performed in seven hospitals in Spain and Portugal. Patients with a postoperative follow-up of less than 20 months and those within the theoretical period of prosthesis resorption were excluded from the study. Regarding the degree of contamination, patients were assessed according to the modified Ventral Hernia Working Group (VHWG) classification. Epidemiological data, hernia characteristics, surgical and postoperative variables (Clavien-Dindo classification) of these patients were analyzed. Risk factors related to long-term recurrence were studied by a multivariate analysis. RESULTS: In 236 cases of P4HB prosthesis implantation, repair in cases of Grade 3 was the most frequent (49.1%), followed by Grade 2 in 42.3% of cases and Grade 1 in 8.4%. The most frequent complications were Grade 1, with the majority occurring during the first year. The overall rate of surgical site occurrences (SSO) was 30%. The hernia recurrence rate was 14.4% (n = 34), with a mean postoperative follow-up time of 41 months (22-61). The multivariate analysis showed that the onlay location of the mesh (OR 1.07; CI 1.42-2.70, p = 0.004) was a significant independent risk factor for recurrence. CONCLUSIONS: The use of a P4HB bioresorbable mesh for the VHR with different degrees of contamination leads to favourable results overall, with an acceptable rate of hernia recurrence. The onlay location of the P4HB prosthesis is the main factor in recurrence in both elective and emergency settings.

Natural products and their mechanisms in potential photoprotection of the skin.

Exposure to solar radiation can generate different types of damage to the skin, including skin cancer. Depending on the duration of the exposure, sun damage can present as sunburn, photoaging, and photoimmunosuppression, among other effects. Using natural products on the skin may aid in preventing the damage caused by exposure to solar radiation, in addition to reducing the adverse side effects of common sunscreens, such as irritation, allergies, phototoxic reactions, photosensitivity, and generation of reactive oxygen species. On the other hand, the UV light absorption capacity of natural products has been reported to be due to the presence of chromophores in their structure, which, when added to the beneficial effects they have on the skin, makes them attractive candidates for use as photoprotectors. The present work gathers updated information regarding skin damage caused by prolonged sun exposure. It also describes the photoprotective effect of several natural products, their mechanism of action, and their preventive and therapeutic potential. For this purpose, the scientific literature was searched using PubMed, Science Direct, and Google Scholar.

Characterization of the Clogging Transition in Vibrated Granular Media.

The existence of a transition from a clogged to an unclogged state has been recently proposed for the flow of macroscopic particles through bottlenecks in systems as diverse as colloidal suspensions, granular matter, or live beings. Here, we experimentally demonstrate that, for vibrated granular media, such a transition genuinely exists, and we characterize it as a function of the outlet size and vibration intensity. We confirm the suitability of the "flowing parameter" as the order parameter, and we find out that the rescaled maximum acceleration of the system should be replaced as the control parameter by a dimensionless velocity that can be seen as the square root of the ratio between kinetic and potential energy. In all the investigated scenarios, we observe that, for a critical value of this control parameter S_{c}, there seems to be a continuous transition to an unclogged state. The data can be rescaled with this critical value, which, as expected, decreases with the orifice size D. This leads to a phase diagram in the S-D plane in which clogging appears as a concave surface.

Nonergodicity in silo unclogging: Broken and unbroken arches.

We report an experiment on the unclogging dynamics in a two-dimensional silo submitted to a sustained gentle vibration. We find that arches present a jerking motion where rearrangements in the positions of their beads are interspersed with quiescent periods. This behavior occurs for both arches that break down and those that withstand the external perturbation: Arches evolve until they either collapse or get trapped in a stable configuration. This evolution is described in terms of a scalar variable characterizing the arch shape that can be modeled as a continuous-time random walk. By studying the diffusivity of this variable, we show that the unclogging is a weakly nonergodic process. Remarkably, arches that do not collapse explore different configurations before settling in one of them and break ergodicity much in the same way than arches that break down.

Slow relaxation dynamics of clogs in a vibrated granular silo.

We experimentally explore the vibration-induced unclogging of arches halting the flow in a two-dimensional silo. The endurance of arches is determined by carrying out a survival analysis of their breaking times. By analyzing the dynamics of two morphological variables, we demonstrate that arches evolve toward less regular structures and it seems that there may exist a certain degree of irregularity that the arch reaches before collapsing. Moreover, we put forward that σ (the standard deviation of all angles between consecutive beads) describes faithfully the morphological evolution of the arch. Focusing on long-lasting arches, we study σ calculating its two-time autocorrelation function and its mean-squared displacement. In particular, the apparent logarithmic increase of the correlation and the decrease of the mean-squared displacement of σ when the waiting time is increased reveal a slowing down of the dynamics. This behavior is a clear hallmark of aging phenomena and confirms the lack of ergodicity in the unclogging dynamics. Our findings provide new insights on how an arch tends to destabilize and how the probability that it breaks with a long sustained vibration decreases with time.

Plastrón apendicular y manejo clínico actual: una decisión a reconsiderar: a propósito de un caso / Appendicular mass and current clinic management: a decision to reconsiderate: about a case

Introducción: La apendicitis es uno de los principales motivos de consulta e intervención quirúrgica en los servicios de urgencias. Debe tratarse oportunamente dado que puede evolucionar hacia una perforación apendicular y con ello a una peritonitis o un plastrón apendicular, en aproximadamente un 10%, e incrementando las morbilidades, como tiempo de reposo o estadía hospitalaria. Actualmente no existe consenso acerca del tratamiento del plastrón apendicular, por ello, el objetivo del presente trabajo es respaldar y promover la alternativa quirúrgica diferida, versus el manejo médico, como el tratamiento más idóneo del plastrón apendicular. Presentación del caso: Se derivó al Hospital Base Valdivia a una escolar, de 8 años y 11 meses de edad, por dolor en hemiabdomen inferior de 3 semanas de evolución acompañado de sensación febril no cuantificada, vómito y diarrea; se diagnosticó un plastrón apendicular, optándose por el manejo médico; evolucionó favorablemente, dándole el alta. En controles posteriores se planificó una apendicectomía, llevándose a cabo con éxito meses después. La biopsia del apéndice extraído evidenció un carcinoma de apéndice cecal, por lo que se inició el estudio de extensión de neoplasia sin encontrar hallazgos patológicos. Discusión: Actualmente el manejo del plastrón apendicular depende del médico tratante y su criterio. Existen ventajas y desventajas entre la elección de un tratamiento médico o quirúrgico, sea inmediato o diferido; dentro de las ventajas del último destacan la prevención de apendicitis recurrentes y detección temprana del carcinoma apendicular, como en el caso presentado, permitiendo de esta forma un mejor pronóstico para el paciente y evitando el uso de terapias más agresivas.

Introduction: Appendicitis is one of the main reasons for consultation and surgery in the emergency department. It must be treated promptly because it can evolve into a ruptured appendix and thus to peritonitis or an appendiceal plastron, by approximately 10%, and increasing the morbidity, as downtime or hospital stay. There is currently no consensus on the treatment of appendicular plastron, therefore, the objective of this work is to support and promote alternative deferred surgical versus medical management, as the most suitable treatment of appendiceal plastron. Case presentation: A girl of 8 years 11 months old consult for pain in lower abdomen of three weeks of evolution, accompanied by feverish feeling, unquantified, vomiting and diarrhea; Is diagnosed a plastron appendiceal opting for medical management, evolving favorably and giving the discharge. In subsequent controls was planned appendectomy, taking place successfully months later. Biopsy of removed appendix showed a appendix cancer, reason why an extension study of neoplasia was initiated without pathological findings. Discussion: Currently the management of appendicular plastron is dependent on the treating physician and judgment. There are advantages and disadvantages of choosing a medical or surgical treatment, immediate or delayed, inside the advantages of the latter include the prevention of recurrent appendicitis and early detection of appendiceal carcinoma, as in the case presented, thus allowing better prognosis for the patient and avoiding the use of more aggressive therapies.

Factores asociados a insuficiencia renal postoperatoria en cirugía de revascularización miocárdica / Factors associated to postoperative kidney failure following myocardial revascularisation

Objetivos: Determinar qué antecedentes clínicos del paciente y factores del procedimiento quirúrgico se asocian con la aparición de insuficiencia renal postoperatoria en pacientes sometidos a cirugía de revascularización miocárdica. Métodos: estudio llevado a cabo entre enero de 2005 y diciembre de 2013, de casos y controles anidado en una cohorte, en la que se incluyeron pacientes sometidos a cirugía de revascularización miocárdica electiva que presentaron insuficiencia renal postoperatoria durante el postoperatorio inmediato hasta el egreso. Los controles estuvieron conformados por pacientes sometidos a cirugía de revascularización miocárdica electiva que no desarrollaron insuficiencia renal postoperatoria inmediata hasta el egreso. Se realizó un modelo de regresión logística para determinar los factores asociados a insuficiencia renal postoperatoria. Las asociaciones se expresaron en razones de disparidad con sus respectivos intervalos de confianza. Resultados: la edad avanzada {OR 1,03 IC95% (1,01-1,04){, la presencia preoperatoria de diabetes mellitus {OR 1,8 IC95% (1,9-3,4){, la insuficiencia cardiaca {OR 2,7 IC 95% (1,1-6,7){ y el mayor tiempo de perfusión {OR 1,02 IC 95% (1,01-1,03){ se asociaron con mayor riesgo de insuficiencia renal postoperatoria, en tanto que el mayor hematocrito {OR 0,86 IC95% (0,82-0,91){ y la mayor fracción de eyección {OR 0,94 IC95% (0,92-0,96){ se relacionaron con disminución del riesgo de insuficiencia renal postoperatoria. Conclusiones: En quienes se realizó revascularización miocárdica los factores asociados a la presentación de insuficiencia renal postoperatoria fueron comorbilidades que se relacionaron con daño renal progresivo dentro y fuera del contexto de la cirugía. Esto implica que las estrategias para minimizar este evento estarán enfocadas a identificar de manera oportuna a estos pacientes y proporcionarles nefroprotección adecuada.

Motivation: To determine which medical history and surgical procedure factors are associated to the onset of postoperative kidney failure in patients undergoing myocardial revascularisation. Methods: Case-control cohort study carried out between January 2005 and December 2013 which included patients who had undergone elective myocardial revascularisation and showed postoperative kidney failure immediately after surgery and until discharge. Controls consisted of patients who had undergone elective myocardial revascularisation and did not develop postoperative kidney failure immediately after surgery. A logistic regression model was used to determine the factors associated to postoperative kidney failure. Associations were expressed as grounds of disparity with their corresponding confidence intervals. Results: old age {OR 1.03 CI 95% (1.01-1.04){, preoperative presence of diabetes mellitus {OR 1.8 CI 95% (1.9-3.4)}, cardiac insufficiency {OR 2.7 CI 95% (1.1-6.7)} and a longer perfusion time {OR 1.02 CI 95% (1.01-1.03)} were associated to a higher risk of postoperative kidney failure, while higher hematocrit {OR 0.86 CI 95% (0.82-0.91)} and higher ejection fraction {OR 0.94 CI 95% (0.92-0.96)} were associated with a decrease of the risk of postoperative kidney failure. Conclusions: In patients who had undergone myocardial revascularisation, risk factors associated to postoperative kidney failure where comorbidities related to internal and external gradual kidney damage outside the context of the surgery. This implies that strategies to minimise this event should be focused on identifying these patients in a timely manner and offering appropriate nephroprotection.

Caracterización epidemiológica de cáncer de esófago en Hospital Base Valdivia, período 2002-2011 / Epidemiologic characterization of esophagus neoplasm, Valdivia Hospital, 2002-2011

INTRODUCCIÓN: El cáncer de esófago posee para el 2007 una tasa de incidencia estimada en Chile de 5,7x100.000 habitantes. Los tipos histológicos más frecuentes son carcinoma de células escamosas y adenocarcinoma, esta última ha experimentado un aumento de su incidencia. OBJETIVOS: Caracterizar población de pacientes diagnosticados con cáncer de esófago, entre los años 2002 y 2011, del Hospital Base de Valdivia (HBV). METODOLOGÍA: Estudio descriptivo retrospectivo, cuyos datos se obtuvieron por revisión de libros de biopsias del Servicio de Anatomía Patológica de Hospital Base Valdivia entre los años 2002-2011 registrando datos sobre sexo, edad y tipo histológico. Los datos fueron tabulados y graficados en programa Excel 2010. RESULTADOS: Se analizaron 151 biopsias, con promedio de edad 70 años. La incidencia promedio fue de 4,14/100.000 habitantes con una relación 5:3 para sexo masculino y femenino respectivamente. La incidencia anual para hombres fue de 1,7 en 2002 y 7,2 en 2011. La incidencia anual promedio para carcinoma escamoso fue de 3,4/100.000 habitantes, para adenocarcinoma 0,58/100.000 habitantes, y otros tipos histológicos 0,2/100.000 habitantes. DISCUSIÓN: La incidencia por género fue más baja para varones que las cifras nacionales, pero con tendencia al alza. El tipo histológico más frecuente fue carcinoma escamoso. A diferencia de lo esperado el adenocarcinoma no tiene tendencia al alza.

INTRODUCTION: The year 2007 the esophageal neoplasms has an estimated incidence in Chile of 5,7/100.000. The most frequently histologic kinds are the Squamous Cell Carcinoma and the Adenocarcinona, the last one has shown an incidence rise. OBJECTIVES: Epidemiologic characterization of esophagus neoplasm cases for the 2002-2011 period. METODOLOGY: Retrospective descriptive study, where the data was obtained by biopsy books revision from the anatomy department at Valdivia hospital. Tabulation and analysis performed whit excel 2010. RESULTS: 151 cases were analyzed, average age were 70 years. The average incidence for men cases: 1,7/100.000 in 2002 and 7,2/100.000 in 2011. The Squamous Cell Carcinoma average incidence: 3,4/100.000 and for the adenocarcinoma: 0,58/100.000. DISCUSSION: The average incidence was lower for men than the national rates, but it's increasing. The mostcommon histologic kind is the quamous Cell Carcinoma. The adenocarcinoma isn't increasing as was expected.

Dual effects of different selenium species on wheat.

Wheat (Triticum aestivum) and its derivative products account for a major source of dietary intake of selenium (Se) in humans and animals, because of its essentiality due to its presence in vital enzymes. Se antioxidant role has resulted in the popularity of agronomic biofortification practises in Se deficient areas. Controlling Se uptake, metabolism, translocation and accumulation in plants will be important to decrease healthy risk of toxicity and deficiency and to help selecting adequate methods for biofortification. Selenate and selenite are the two main inorganic Se forms available in soil and in most of the studies are given separately. That study reveals that both Se species behave differently but combined the prevalent pattern is that of selenite; so it is taken up faster and it seems that interferes with selenate uptake and transport. Selenium has dual effects on wheat plants; at low concentrations it acts as growth stimulant whereas at high concentrations it reduces root elongation and biomass production and alters uptake and translocation of several essential nutrients.

Epidemiología del cáncer papilar de tiroides: Hospital Regional deAntofagasta y Valdivia: período 2005–2011 / Epidemiology of the papillary thyroid cancer: Regional Hospital of Antofagasta and Valdivia: period 2005-2011

El Cáncer de Tiroides constituye la neoplasia del sistema endocrino más prevalente en el mundo (1 por ciento de cánceres totales); el tipo morfológico más común corresponde al Carcinoma Papilar de Tiroides (CPT). Chile cuenta con pocas caracterizaciones epidemiológicas de esta patología, generando un verdadero problema de salud pública al subvalorarla. OBJETIVO: Obtener una visión global del CPT y comparar datos epidemiológicos entre Hospital Regional de Antofagasta (HRA) y Hospital Regional de Valdivia (HRV). MATERIAL Y MÉTODO: Se realizó un estudio de tipo descriptivo retrospectivo de fichas clínicas con diagnóstico confirmado mediante biopsia de CPT, residentes en la II o XIV región de Chile, durante el período 2005-2011. Los datos recabados se tabularon según sexo, edad y región respectiva mediante Excel 2011, calculando adicionalmente la tasa anual de CPT por región. Los datos y valores obtenidos fueron descritos y comparados entre ellos. RESULTADOS: El HRA presentó 79 casos de CPT, con tasa anual promedio (TAP) de 2,03x100.000 hab.; 88,6 por ciento fueron mujeres y 11,4 por ciento hombres; 30,4 por ciento eran <45 años y 69,6 por ciento >45 años. El HRV presentó 88 casos, con TAP de 3,34x100.000 hab.; 84,1 por ciento fueron mujeres y 15,9 por ciento hombres; 52,3 por ciento eran ≤45 años y 47,7 por ciento >45 años. DISCUSIÓN: Según regiones la II presentó menos TAP de CPT que la XIV, existiendo en la última una tendencia al alza y en la II a la disminución, contrastando con la información conocida. Variaron los grupos etarios afectados, la II presentó mayor cantidad de casos >45 años, en cambio, en la XIV la mayoría fue <45 años, contrastando con la literatura...

Thyroid cancer is the more prevalent endocrine neoplasia in the world (1 percent of total cancers); the most common morphological type corresponds to Papillary Thyroid Carcinoma (CPT). Chile has few epidemiologic characterization of this pathology, creating a real public health problem because the underestimating of it. OBJECTIVE: Get an overview of CPT and compare epidemiological data, between Antofagasta Regional Hospital (HRA) and Valdivia Regional Hospital (HRV).METHODS: We performed a retrospective descriptive study of medical records with biopsy-confirmed diagnosis of CPT, residents of the II or XIV region of Chile, during the period 2005-2011. The collected data was tabulated by sex, age and region concerned by Excel 2011, additionally calculating the annual rate of CPT by region. The data and values obtained were described and compared with each other. RESULTS: The HRA presented 79 cases of CPT, with average annual rate (TAP) of 2.03x100.000 pop., 88.6 percent were women and 11.4 percent men, 30.4 percent were ≤45 years and 69.6 percent percent>45 years. The HRV presented 88 cases, with TAP of3.34x100.000 pop., 84.1 percent were women and 15.9 percent men, 52.3 percent were <45 years and 47.7 percent >45 years. DISCUSSION: The second region had less TAP CPT compared to the XIV region. In the last one there is an increased incidence in general, while in region II tends to decrease, contrasting with the existing information. A variation in the affected age groups was found, the II Region had more cases >45 years, however, in XIV region the majority was <45 years, in contrast to the literature...

A mouse model to study the alterations in haemostatic and inflammatory parameters induced by Lonomia achelous caterpillar haemolymph.

A mouse model was established to reproduce the haemorrhagic syndrome which occurs in humans after accidental contact with the hairs of the caterpillar Lonomia achelous (LA) and measures the haemostatic and inflammatory alterations that occur as a result of this contact. Mice were injected intradermally with different doses (0.4, 0.8 and 1.6 mg/animal) of L. achelous haemolymph (LAH). Haematological (haemoglobin, haematocrit, platelet count, differential leukocyte count), haemostatic (fibrinogen, plasminogen, factor XIII [FXIII], fibrinolytic activity) and inflammatory parameters (tumour necrosis factor alpha [TNF-α], nitric oxide [NO]) were measured at different times up to 48 h. C57BL/6 mice responded to LAH injection, in terms of these parameters, in a manner similar to that seen in humans, whereas the BALB/c mice were unresponsive. In C57BL/6 mice injected with LAH, time course measurements showed: a) a reduction in the haemoglobin, haematocrit, fibrinogen, FXIII and plasminogen levels, b) no effect on the platelet count and c) immediate leukocytosis and an increase in the fibrinolytic activity in plasma. An inflammatory response (TNF-α) was observed within 1 h post-injection, followed by a more persistent increase in serum NO. These findings suggest that C57BL/6 mice represent a useful model of the haemorrhagic syndrome observed in humans who have suffered contact with the caterpillar, permitting a deeper understanding of the role of the inflammatory response in the haematological and haemostatic manifestations of this syndrome.

Hipotensión ortostática en enfermedad de Parkinson / Orthostatic hypotension in Parkinson's disease

The current concept of Parkinson’s disease comprises a group of non-motor symptoms: neuropsychiatric disorders, sleep disturbances and dysautonomia, among others. Orthostatic hypotension is a frequent problem that impairs the patient’s quality of life. We review the symptoms of this disorder, its pathogeny and the available diagnostic tools. We emphasize the early suspicion and show the treatment options, based on the available evidence and our experience.

Neurinoma del acústico manifestado como una parálisis facial / Acoustic neurinoma shown as a facial palsy

El neurinoma del acústico es el tumor benigno más frecuente a nivel del ángulo pontocerebeloso (ACP), que provoca lesiones de tipo compresivo en las estructuras cerebrales adyacentes a su recorrido, manifestándose habitualmente por una hipoacusia neurosensorial, acúfenos con o sin vértigo unilaterales, por lo que debe conocerse la amplia variedad clínica con que se presenta desde su inicio, entre ellas como una parálisis facial. Presentamos el caso de un schwannoma vestibular en una embarazada diagnosticado por una parálisis facial periférica

Acoustic neurinoma is the most frequent benign tumour at the cerebellopontile angle. It causes compressive type lesions in adjacent cerebral structures. Its usual symptoms are sensorineural hearing loss and tinnitus with or without unilateral vertigo, which is why we have to know the wide variety of clinical signs it can present from its beginning, including facial palsy. We present the case of a vestibular schwannoma in a pregnant lady diagnosed by a peripheral facial palsy

Cinética de crecimiento in vitro de dos cepas de Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) en células miocárdicas de roedores con diferente susceptibilidad / In vitro growth kinetics of two Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) clones in myocardial cells from rodents of different susceptibility

In vitro growth kinetics of two Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) clones in myocardial cells from rodents of different susceptibility. Two Trypanosoma cruzi isolates, TCR-4 from Costa Rica and UES-1 from El Salvador, were studied in vitro to compare their infectivity or resistance and intracellular replication in myocardial cells in three strains of mice and rats: NGP white mice, C3 H mice and Sprague Dowley rats. Myocardial cells were cultured on coverslips at 37 degrees C in a humid 10% CO2 atmosphere and then infected at a ratio of one tripomastigote per cell. Samples were studied after 24, 72, 96 and 120 h of infection to determine parasite infection capacity and intracellular multiplication. Both parasites had the highest infection capacity in C3 H mice, followed by NGP mice cells with a very low infection rate. Lastly, almost no Trypanosoma cruzi multiplication was observed in Sprague Dowley rats, suggesting a strong natural resistance in this animal to both strains of the parasite. The UES-1 isolate presented higher multiplication and greater invasion than the TCR-4 strain, showing greater virulence of UES-1 in heart cells, at least in vitro.

[Acoustic neurinoma shown as a facial palsy]. / Neurinoma del acústico manifestado como una parálisis facial.

Acoustic neurinoma is the most frequent benign tumour at the cerebellopontile angle. It causes compressive type lesions in adjacent cerebral structures. Its usual symptoms are sensorineural hearing loss and tinnitus with or without unilateral vertigo, which is why we have to know the wide variety of clinical signs it can present from its beginning, including facial palsy. We present the case of a vestibular schwannoma in a pregnant lady diagnosed by a peripheral facial palsy.

Factores de riesgo de enfermedades crónicas no transmisibles en funcionarios de una empresa de servicios financieros de la Región Metropolitana / Risk factors for non communicable chronic diseases among workers of a financial company

Background: The epidemic of cardiovascular diseases in Chile, requires the development of strategies in health promotion and prevention. Aim: To assess the prevalence of risk factors for chronic non communicable diseases among workers of a financial company in Metropolitan Santiago. Material and Methods: Assessment of 2,225 workers (1,383 males with a median age of 49 years and 842 females with a median age of 43 years). All answered an enquiry about education, medical history, smoking habits and physical activity. Body mass index and blood pressure were measured and a blood sample was obtained to measure blood glucose and lipid levels. Logistic repression models were used to determine the main risk factors for hypertension, diabetes, obesity, hypercholesterolemia and hyperuricemia. Results: Sixteen percent of studied subjects were obese, 49% had overweight, 57% had hypercholesterolemia, 28% had high blood pressure, 4% were diabetic, 4% had hyperuricemia, 45% smoked and 83% were sedentary. Each worker had a mean of 2.4±1.1 risk factors. This figure was significantly higher among men, obese subjects, those older than 40 years and those with a lower educational level. Conclusions: There is an important disease burden among the studied subjects, specially among obese and older individuals. Healthy lifestyles should be promoted in this population.

Identification and purification of actin from the subpellicular network of Toxoplasma gondii tachyzoites.

Toxoplasma gondii infects cells through dynamic events dependent on actin. Although the presence of cortical actin has been widely suggested, visualisation and localisation of actin filaments has not been reported. The subpellicular cytoskeleton network is a recently described structure possibly involved in the dynamic events. Using non-ionic detergent extractions, the cortical cytoskeleton network was enriched and used for the isolation and identification of actin. Actin was detected by Western blots in extracts of cytoskeleton networks, and it was localised by gold staining in the network and in both the apical end and the posterior polar ring. Actin was isolated from subpellicular cytoskeleton extracts by binding to DNase I, and it polymerised in vitro as filaments that were gold-decorated by a monoclonal anti-actin antibody. Filaments bound the subfragment 1 of heavy meromyosin, although with atypical arrangements in comparison with the arrowheads observed in muscle actin filaments. Treatment with cytochalasin D and colchicine altered the structural organisation of the subpellicular network indicating the participation of actin filaments and microtubules in the maintenance of its structure. Actin filaments and microtubules, in the subpellicular network, participate reciprocally in the maintaining of the parasite's shape and the gliding motility.

Immersion and emotion: their impact on the sense of presence.

The present study is designed to test the role of immersion and media content in the sense of presence. Specifically, we are interested in the affective valence of the virtual environments. This paper describes an experiment that compares three immersive systems (a PC monitor, a rear projected video wall, and a head-mounted display) and two virtual environments, one involving emotional content and the other not. The purpose of the experiment was to test the interactive role of these two media characteristics (form and content). Scores on two self-report presence measurements were compared among six groups of 10 people each. The results suggest that both immersion and affective content have an impact on presence. However, immersion was more relevant for non-emotional environments than for emotional ones.