Coating PTFE vascular prostheses with a fibroblastic matrix improves cell retention when subjected to blood flow.

An investigation was made into the effect of blood flow on endothelial cells (EC) and mesothelial cells (MC) seeded on a vascular expanded polytetrafluoroethylene (ePTFE) prosthesis coated with a fibroblastic matrix. Endothelial cells were obtained from the external jugular vein and MC from the omentum. To test the performance of prostheses, a custom designed, femoral "ex vivo" circuit was developed in mongrel dogs. Four study groups were established: a control group, A1, where prostheses were uncoated and seeded with EC; a second control group, A2, where prostheses were uncoated and seeded with MC; group B1 where prostheses were coated with a fibroblastic matrix and seeded with EC; and group B2 where coated prostheses were seeded with MC. All cells were labeled with 111Indium oxine (10 microCi/mL) before seeding. After the seeded cells had formed a monolayer on the ePTFE prostheses (which took approximately 24 h) the prostheses were placed in the "ex vivo" circuit. The rates of blood flow to which prostheses were exposed were measured at the point of inflow (117.5 +/- 12.50 mL/min, mean +/- SD) and outflow (72.6 +/- 14.3 mL/min). MC showed a greater baseline radionuclide uptake than did EC. The cells of groups B1 and B2 adhered sufficiently to the fibroblastic matrix and covered enough of the prosthetic surface to be positioned in the "ex vivo" circuit (76.90 +/- 8.24% surface covered in EC-seeded prostheses and 71.65 +/- 6.23% in MC-seeded prostheses). After exposure to blood flow the quantity of radionuclide-labeled cells and the prosthetic surface covered by them were greatly reduced though the fibroblast-coated prostheses showed greater cell retention

Mesothelial versus endothelial cell seeding: evaluation of cell adherence to a fibroblastic matrix using 111In oxine

The aim of this study was to compare the behaviour of mesothelial cells (MC) to that of endothelial cells (EC) when seeded onto a PTFE, prosthesis coated with a fibroblastic matrix. Three study groups were examined: a control group (Control) of PTFE prostheses with a fibroblast matrix (n = 8); Group EC, PTFE prostheses seeded with EC on a fibroblastic matrix (n = 8); and Group MC, PTFE, prostheses seeded with MC on a fibroblastic matrix (n = 8). All cell types were labelled with 111In (100 microCi/ml) 24 h after seeding, when the cells had formed a monolayer on the prosthetic surface. Radioactive levels were measured at 2, 4, 6, and 24 h. Both EC and MC showed optimal adherence. The MC had a better radioactive uptake and retention than the EC. The number of EC and MC cells that remained adherent to the matrix was large enough to ensure complete covering of the prosthetic surface. The use of MC is therefore feasible as an optimal alternative for achieving a natural covering on vascular prostheses prepared with a fibroblastic matrix

Study of biochemical substrate and role of metalloproteinases in fascia transversalis from hernial processes

The aim of this study was to examine the fascia transversalis (FT) from patients with direct and indirect hernia in an attempt to identify possible differences between each type of hernia. FT samples were obtained from 36 patients presenting inguinal hernia (23 indirect hernia and 13 direct hernia) who underwent surgery. We have analysed the ultrastructure of the fascia surrounding the hernial lesions, the proline and lysine hydroxylation in the tissue, the type I-type III collagen ratio and the presence of metalloproteinases. We have not detected ultrastructural differences in the collagen fibrils from FT in direct and indirect hernias. However, the interfibrillar matrix was more abundant in direct hernias, showing abundant electron-dense particles. No differences in proline hydroxylation were observed between each type of hernia. A small decrease in lysine hydroxylation was detected in patients with direct hernia. Enzyme-linked immunosorbent assays (ELISAs) showed no statistically significant differences in the type I-type III collagen absorbance ratios. Immunohistochemistry revealed no differences in the expression of matrix metalloproteinase-1. FT from patients presenting direct hernia showed a very strong staining vs. metalloproteinase-2 when compared with that observed in indirect hernia

Rapid thawing increases the fragility of the cryopreserved arterial wall

To extend present knowledge of the biomechanical and structural changes which occur in the cryopreserved, rapidly thawed arterial wall. Minipig iliac arterial segments were cryopreserved at -196 degrees C in either minimum essential medium or Wisconsin solution. Fresh segments served as the control group. After 1 month, the specimens were rapidly thawed (37 degrees C) and processed for biomechanical, ultrastructural, morphological and immunohistochemical (MMP-1, MMP-2, MMP-3 and MMP-9) analysis. Visualisation of apoptotic cells was performed by TUNEL method. For the mechanical distension analysis, an in vitro circuit was designed. The cryopreserved segments showed a 42% incidence of spontaneous fracture and the appearance of microfractures which affected the endoluminal third of the vessel. An accumulation of liquid in the subelastica was observed. An increased expression of wall-degradative enzymes (mainly MMP-2) was also observed following cryopreservation. No significant differences were detected in the proportional elasticity module or tensile strength of the specimen groups. No differences in mechanical distension were observed between groups after the vessel segments were subjected to the pulsatile circuit flow for 72 h. Cell damage was most intense in the specimens cryopreserved in Wisconsin solution. Cryopreservation in both the solutions employed, followed by rapid thawing, induce changes in the permeability which increase the fragility of the cryopreserved arterial wall. Both increased expression of wall-degradative enzymes and accumulation of liquid may contribute to graft failure after implantation

Evaluation of the smooth muscle cell component and apoptosis in the varicose vein wall

This study was designed to evaluate the role of the smooth muscle cell and the apoptosis in the pathogenesis of the varicose vein. Segments of saphenous vein were obtained from healthy subjects and from those with varicose veins. The vein specimens were subdivided according to subject age (younger or older than 50 years) and according to the varicose vein source (distal or proximal). Morphological, ultrastructural, cell proliferation (anti-PCNA method) and cell death (TUNEL method) analysis were performed. The walls of healthy, control vein specimens acquired a more collagenous and papillomatous appearance with age. A slight increase in the number of TUNEL-positive cells was also observed in specimens from older subjects. The proportion of apoptotic cells was much greater in the varicose veins than in control specimens. Most cellular alterations were seen in proximal varicose segments obtained from young subjects. These specimens showed hypertrophic areas with a high degree of cellularity (both in the media and in the thickened intima). The highest proportion of apoptotic cells and collagenisation were also observed in these areas. The enhanced number of apoptotic cells in varicose veins observed mainly in proximal/young vein specimens could be responsible, at least in part, for the acceleration of the final fibrosclerotic process characteristic of the varicose vein wall

Validez y fiabilidad de un instrumento para la valoración de la entrevista clínica en médicos residentes de medicina de familia: el cuestionario GATHA-RES

ObjetivoComprobar la validez de contenido, la consistencia interna y la fiabilidad intraobservador de un cuestionario para la evaluación de la comunicación médico-paciente de los residentes de medicina de familia.DiseñoEstudio observacional, de validación de un instrumento de medida.EmplazamientoNivel de atención primaria. Unidades docentes de medicina de familia y comunitaria.Población de estudioPara el análisis de validez, 25 médicos residentes de medicina familiar y comunitaria. Para el análisis de fiabilidad, 48 médicos de la misma especialidad.Mediciones e intervencionesPara la construcción del cuestionario, se partió de una versión (GATHA-BASE), compuesta por 42 ítems seleccionados por un panel compuesto por 60 médicos de familia. Para la validez de contenido, se utilizaron 68 encuentros clínicos con pacientes simulados, que fueron videograbados y evaluados. La validez de contenido del cuestionario se estudió mediante un análisis factorial, y para medir su consistencia interna se calcularon los coeficientes alfa de Cronbach. La fiabilidad intraobservador de la versión GATHA-RES fue evaluada mediante los índices kappa y los coeficientes de correlación intraclase.ResultadosObtuvimos una versión del GATHA-RES con 27 ítems. El análisis factorial reveló la existencia de 9 factores: «empatía», «anamnesis», «bidireccionalidad», «negociación», «información», «miscelánea 1», «miscelánea 2» y «centrado en el paciente», que mostraron una buena correlación con los contenidos teóricos y formales del cuestionario original (inicialmente agrupados en 3 secciones: actitudes, tareas comunicacionales y habilidades). Todos los coeficientes de correlación intraclase presentaron cifras ≥ 0,90.ConclusionesEl cuestionario GATHA-RES es un instrumento válido y fiable que puede ser usado para la evaluación de las habilidades comunicacionales de los médicos de familia en formación.ObjectiveTo check the validity of content, the internal consistency and the intra-observer reliability of a questionnaire to evaluate the doctor-patient communication of family medicine residents.DesignObservation study, to validate a measurement instrument.SettingPrimary care. Family and community medicine teaching units.Study populationFor the validity analysis: 25 family and community medicine residents. For the reliability analysis: 48 doctors in the same speciality.Measurements and interventionsThe questionnaire was constructed on the basis of a version (GATHABASE) composed of 42 items selected by a panel of 60 general practitioners. For content validity, 68 clinical encounters with simulated patients, video-recorded and evaluated, were used. The questionnaire's validity content was studied through a factorial analysis. To measure its internal consistency, Cronbach's alpha coefficients were calculated. Intra-observer reliability of the GATHA-RES version was evaluated through the kappa indexes and the intra-class correlation coefficients.ResultsWe obtained a version of the GATHA-RES with 27 items. The factorial analysis revealed that there were 9 factors («empathy», «anamnesis», «two-way communication», «negotiation», «information», «miscellaneous 1», «miscellaneous 2» and «patient-focused») which showed close correlation with the theoretical and formal contents of the original questionnaire (originally grouped in three sections: attitudes, communication tasks and skills). All the intraclass correlation coefficients had figures ≥ 0.90.ConclusionsThe GATHA-RES questionnaire is a valid and reliable instrument that can be used for evaluating the communication skills of general practitioners in training

Nutritional status and clinical outcome of children on continuous renal replacement therapy: a prospective observational study

BACKGROUND: No studies on continuous renal replacement therapy (CRRT) have analyzed nutritional status in children. The objective of this study was to assess the association between mortality and nutritional status of children receiving CRRT. METHODS: Prospective observational study to analyze the nutritional status of children receiving CRRT and its association with mortality. The variables recorded were age, weight, sex, diagnosis, albumin, creatinine, urea, uric acid, severity of illness scores, CRRT-related complications, duration of admission to the pediatric intensive care unit, and mortality. RESULTS: The sample comprised 174 critically ill children on CRRT. The median weight of the patients was 10 kg, 35% were under percentile (P) 3, and 56% had a weight/P50 ratio of less than 0.85. Only two patients were above P95. The mean age for patients under P3 was significantly lower than that of the other patients (p = 0.03). The incidence of weight under P3 was greater in younger children (p = 0.007) and in cardiac patients and in those who had previous chronic renal insufficiency (p = 0.047). The mortality analysis did not include patients with pre-existing renal disease. Mortality was 38.9%. Mortality for patients with weight < P3 was greater than that of children with weight > P3 (51% vs 33%; p = 0.037). In the univariate and multivariate logistic regression analyses, the only factor associated with mortality was protein-energy wasting (malnutrition) (OR, 2.11; 95% CI, 1.067-4.173; p = 0.032). CONCLUSIONS: The frequency of protein-energy wasting in children who require CRRT is high, and the frequency of obesity is low. Protein-energy wasting is more frequent in children with previous end-stage renal disease and heart disease. Underweight children present a higher mortality rate than patients with normal body weight

Continental shelf zones influenced by the suspended matter flows coming from Cadiz Bay

Due to the diversity of environments and hydrodynamics in Cadiz Bay, it is of interest to study the dynamics of sedimentary exchange between the coastal zones and continental shelf. The most abundant clay minerals on the floor of the continental shelf and Cadiz Bay, and in the particulate matter in suspension, are: illite, smectite, kaolinite + chlorite, and the interstratified clay minerals illite-smectite. The average concentration of suspended matter is 6.5 mg/l, the lowest (1.37 mg/l) being found on the inner shelf and in the inner zones of the bay less affected by currents and surge. The highest values (14 mg/l) are found in the outer bay, consistent with the distribution of muddy facies on the sea floor. The flow paths have been established from the local variations in the mineralogical associations found at the sampling stations, and by means of the alignments of the lowest values of the factor loadings at those stations most affected by the flows. The mineralogical similarity of the components of the clay fraction is related to the mixing action undergone by the components of the suspended matter reaching the bay from various sources, probably produced by the continuous action of the tidal ebb currents flowing from the inner sectors of the bay towards the continental shelf.El estudio de la dinámica de intercambio sedimentario entre las zonas litorales y la plataforma continental es de gran interés en el caso de la bahía de Cádiz, debido a su diversidad de ambientes y situaciones hidrodinámicas. Los minerales de la arcilla más abundantes en los fondos de la plataforma y la bahía, y en la materia en suspensión, son ilita, esmectita, caolinita + clorita e interestratificados ilita-esmectita. La concentración de materia sólida en suspensión indica un contenido promedio de 6,5 mg/l, apareciendo los mínimos (1,37 mg/l) en la plataforma interna y en zonas internas de la bahía no afectadas por corrientes y oleaje. Los valores más altos se dan en la bahía externa (14 mg/l), de acuerdo con la distribución de facies fangosas en el fondo. Las trayectorias de los flujos salientes se han establecido a partir de las variaciones locales de las asociaciones mineralógicas en las diferentes estaciones de muestreo, alineándose los valores más bajos de los factores en las estaciones más afectadas por la acción de los flujos. La similitud mineralógica de los componentes de la fracción arcilla en todos los ambientes se debe a la mezcla de componentes de la materia en suspensión que, desde diferentes fuentes, llegan a la bahía, y es favorecida por la acción de la corriente de reflujo mareal desde el sector más interno de la bahía a la plataforma continental.Instituto Español de Oceanografí

A novel controlled drug-delivery system for growth hormone applied to healing skin wounds in diabetic rats

Controlled release systems for drugs, hormones and growth factors can be particularly useful in tissue repair processes. These systems act as a biodegradable support containing the substance to be delivered, allowing their gradual release. In the past years, the local application of growth factors has acquired special relevance as a therapeutic option for use in subjects who show de cient tissue scarring, the hormone dose being the limiting factor for its success. In this study, the in vitro biocompatibility of a copolymer formed by vinylpyrrolidone and 2-hydroxyethyl methacrylate, used as an administration vehicle for hGH, was evaluated. The system was then tested in vivo in terms of its capacity for healing incisional wounds in healthy and diabetic rats. For the in vitro studies, polymer and hormone degradation rates were determined, and polymer biocompatibility was evaluated in broblast cultures. In the in vivo experiments, an incision was made in the back of the animals, and polymers discs with/ without hGH, were introduced in the aperture. Morphological, immunohistochemical and morphometric evaluations were performed on wound tissue specimens 3¿10 days after surgery. In vitro, the polymer was found to be biodegradable and showed no toxic effects on broblasts, the hormone being slowly released to the culture medium. In untreated diabetic rats, a delayed skin scarring and cell response were observed, compared to that noted in healthy animals. Skin closure, keratinisationand brosis occurred earlier in the presence of the polymer-hGH system. The use of this co-polymer as an administrationvehicle for hGH improves the wound scarring process in the pathological setting of diabetes