A new detector for the beam energy measurement in proton therapy: a feasibility study.

The proof of concept of a new device, capable of determining in a few seconds the energy of clinical proton beams by measuring the time of flight (ToF) of protons, is presented. The prototype consists of two thin ultra fast silicon detector (UFSD) pads, aligned along the beam direction in a telescope configuration and readout by a digitizer. The method developed for extracting the energy at the isocenter from the measured ToF, validated by Monte Carlo simulations, and the procedure used to calibrate the system are also presented and discussed in detail. The prototype was tested at the Centro Nazionale di Adroterapia Oncologica (CNAO, Pavia, Italy), at several beam energies, covering the entire clinical range, and using different distances between the sensors. The measured beam energies were benchmarked against the nominal CNAO energy values, obtained during the commissioning of the centre from the measured ranges in water. Deviations of few hundreds of keV have been achieved for all considered proton beam energies for distances between the two sensors larger than 60 cm, indicating a sensitivity to the corresponding beam range in water smaller than the clinical tolerance of 1 mm. Moreover, few seconds of irradiation were necessary to collect the required statistics. These preliminary results indicate that a telescope of UFSDs could achieve in a short time the accuracy required for the clinical application and therefore encourage further investigations towards the improvement and the optimization of the present prototype.

Positive allergy study (Intradermal, patch, and lymphocyte transformation tests) in a case of isoniazid-Induced DRESS

No disponible

Genotoxicity in oral epithelial cells in children caused by nickel in metal crowns.

The micronucleus (MN) assay evaluates the effects of low doses of genotoxic carcinogens and can detect structural lesions that survive mitotic cycles. The objective of this study was to determine both the genotoxicity of nickel (Ni) in buccal epithelial cells and the urinary excretion of Ni in children with metal crowns. This was a prospective longitudinal study based on 37 patients selected at the Facultad de Odontología de la Universidad Autónoma de Coahuila. MN assays were performed using buccal cells from the 37 patients, and Ni levels were determined from urine samples using inductively coupled plasma mass spectrometry at 1 (basal value), 15, and 45 days following the placement of crowns in each patient. Ni urinary excretion levels increased from 2.12 ± 1.23 to 3.86 ± 2.96 mg Ni/g creatinine (P < 0.05) and the frequency of exposed micronuclei increased from 4.67 ± 0.15 to 6.78 ± 0.167/1000 cells (P < 0.05) between 1 and 45 days post-crown placement. These results suggest that odontological exposure to metal crowns results in genotoxic damage at the cellular level of the oral mucosa and an increase in the urinary excretion of Ni within 45 days of exposure.

Left atrial reduction and mitral valve surgery: the "functional-anatomic unit" concept.

The desired outcome for patients undergoing mitral valve surgery includes both good function of the mitral valve, and preservation and restoration of sinus rhythm. To achieve such an outcome, we evolved the concept of the left atrium and mitral valve as a "functional anatomic unit." In this report, we describe a technique for reduction in left atrial size, isolation of the pulmonary veins, and amputation of the left atrial appendage in combination with mitral valve repair. We performed such a procedure in 4 patients, with rheumatic mitral valve disease and chronic atrial fibrillation, with restoration of good valve function and sinus rhythm at 16 to 20 months after surgery.

Loss of NF-kappaB activity during cerebral ischemia and TNF cytotoxicity.

Recent evidence implicates tumor necrosis factor (TNF), a cytokine with both cytotoxic and cytoprotective activities, in the pathogenesis of cerebral ischemia. The development of TNF cytotoxicity is dependent upon the balance between the activities of intracellular signaling pathways that mediate either apoptotic or anti-apoptotic effects. One critical protective signaling mechanism is the activation of nuclear factor (NF)-kappaB, a ubiquitous transcription factor that regulates expression of anti-apoptotic gene products. Here we show the distribution and kinetics of NF-kappaB activation and the correlation between loss of NF-kappaB activity, TNF up-regulation, and apoptosis in a standardized rat model of focal cerebral ischemia. We observed a rapid and progressive ischemia-induced loss of p65 immunoreactivity within the ischemic core and nearby penumbra. These findings were confirmed by Western blot analysis of nuclear extracts and by electrophoretic mobility shift assay. The anatomical area of suppressed NF-kappaB activity overlapped significantly with the zones of TNF overexpression and apoptosis. Loss of NF-kappaB activity and increased TNF expression preceded the onset of cell death. Direct evidence that loss of NF-kappaB activity can sensitize brain cells to TNF cytotoxicity was obtained in vitro by co-administration of MG-132, an inhibitor of NF-kappaB activation, and TNF to neuronal-like and glial-like cell cultures. Inhibition of NF-kappaB significantly increased the sensitivity of these cultures to TNF cytotoxicity, indicating that the observed loss of neuronal NF-kappaB activity during cerebral ischemia can participate in the development of TNF-induced cytotoxicity.

Reliability of diagnostic tests for contact allergy to mydriatic eyedrops.

Adverse reactions due to the administration of mydriatic eyedrops are not uncommon. In Spain, the most commonly used are phenylephrine, tropicamide and cyclopentolate hydrochloride. In this study, 37 patients with adverse reactions to the administration of mydriatic eyedrops were investigated from January 1993 to June 1997. The aim was to assess the reliability of the diagnostic methods used, particularly the adequate concentration of allergens and the introduction of conjunctival challenge as a safe and accurate diagnostic tool in those patients who could not be diagnosed by other methods. Phenylephrine was the drug most frequently causing sensitization (93.5%) among the 31 allergic patients. Preservatives were the cause in only 1. Patch testing detected allergy in 68.5% of the subjects. 2 concentrations (1% and 10%) and vehicles (pet. and aq.) were used for phenylephrine. The most reliable was 10% aq. Reading at D4 was more useful than at D2. The sensitivity of the patch test was low (72.4%) and its negative predictive value (NPV) poor (42%). In 24% of patients, allergy to phenylephrine was detected only by conjunctival challenge test. This diagnostic method is safe and helpful and has not previously been used to diagnose adverse reactions due to mydriatic eyedrops.

Length of postpartum anestrus in goats in subtropical Mexico: effect of season of parturition and duration of nursing.

The aim of this study was to determine whether season of birth and length of nursing affected the duration of postpartum anestrus in Creole female goats maintained on a constant plane of nutrition in subtropical Mexico. Three experiments were conducted in the Laguna region in the State of Coahuila, Mexico (26 degrees N). In the first experiment, 34 goats gave birth in January; in the second, 31 females gave birth in May; and in the third, 22 goats kidded in October. At parturition, females were allocated to 1 of 3 groups based on body weight and date of parturition: kids were weaned at 2, 30 or 90 d according to their group. After weaning, females were milked manually once a day until the end of the study. All animals were kept in a shed and were fed alfalfa ad libitum and given 200 g of concentrate daily. Starting 1 wk after parturition, estrous behavior was detected twice daily using an apron-bearing male, and blood samples were obtained twice weekly to determine ovarian activity from the plasma progesterone levels. A strong effect of month of parturition was found on the duration of postpartum anestrus (P < 0.0001), which was longer in females kidding in January (about 200 d) than in those kidding in May (about 100 d) or October (about 50 d). A tendency for an interaction between season of parturition and length of nursing was observed in the length of anovulation (P < 0.07): for parturition in October, anestrus was longer when kids were weaned after 90 d than after 2 or 30 d (P < 0.01). Season of parturition also affected dates of reinitiation of ovulatory and estrous activity (P < 0.001). Proportions of normal, short and long cycles and of associations between estrous and ovulations were not influenced by season of parturition or the age of weaning. These data demonstrate that in subtropical latitudes, season of parturition can dramatically influence the duration of postpartum anestrus independently of the availability of food.

Occupational asthma caused by fish inhalation.

Occupational asthma (OA) due to fish inhalation, confirmed by specific bronchial challenge (SBC), has not been described as yet in medical literature, as far as we know. We describe two patients whose asthma was induced by occupational exposure to fish and confirmed by serial measurements of PEFR and SBC. Two fish-processing workers reported asthma symptoms related to their workplace. They were skin tested with fish extracts and their sera assayed for IgE antibodies to various fish species. Nonspecific bronchial reactivity was assessed by methacholine challenge. The occupational relationship was confirmed by PEFR monitoring in working and off-work periods. SBC with fish extracts was carried out to confirm the diagnosis of OA. Skin tests with raw and cooked plaice, salmon, hake, and tuna in patient 1 and anchovy, sardine, trout, salmon, Atlantic pomfret, and sole in patient 2 were positive. Specific IgE serum antibodies were found to salmon in patient 1 and to trout, anchovy, and salmon in patient 2. PEFR measurements differed significantly (P < 0.001) between work and off-work periods for both patients. A bronchial challenge with methacholine was positive in patient 1. SBC with raw hake, salmon, plaice, and tuna extracts in patient 1 and raw salmon extract in patient 2 were all positive with an immediate response. SBC with Dermatophagoides pteronyssinus extract was entirely negative in both patients. In three asthmatic, non-fish-allergic controls, SBC with tuna, hake, salmon, and plaice were all negative. These results suggest that fish inhalation can elicit IgE-mediated occupational asthma.

Transversal trans-septal biatrial approach for mitral valve surgery.

A surgical approach to the mitral valve is very important to visualize all valvular and subvalvular structures. We have used a transversal trans-septal biatrial approach in some mitral procedures. From January 1994 to May 1994, 11 patients were operated on using this technique. Patient ages ranged from 28 to 74 years. Five cases (45.5%) were cardiac reoperations and six (54.5%) were first operations. Three case (27.3%) were mitral reconstructions, 3 (27.3%) were mitral replacement due to mechanical mitral valve thrombosis, 1 (9.1%) as a result of bioprosthetic mitral valve degeneration, 4 (36.4%) were mitral valve replacements for calcified mitral valve disease one case (9.1%) was tricuspid valve replacement due to severe tricuspid insufficiency. There were 4 case (36.4%) of tricuspid valvuloplasties besides the mitral procedures. There was no operative mortality, and all patients preserved their preoperative cardiac rhythm. No important bleeding or supra-ventricular arrhythmias were seen in any case. Aortic cross-clamping and extracorporeal circulation times were comparable with the traditional approach through the left atrial alone. So, we think that this is a very easy and useful technique to expose the mitral valve during some procedures above it, overall when the left atrium is small and total visualization of the mitral is not possible with the traditional approach through the left atrial alone.

Comportamiento de puerperas adolescentes y la intervención de enfermería basada en el modelo de Callista Roy / Puerperal behavior of adolescents and nursing intervention based on the model Callista Roy

Analiza los comportamientos de adaptación manifestados por las puérparas primíparas adolescentes, entre las seis a las veinticiautro horas del puerperio y la intervención de enfermería ofrecida durante ese período, utilizando el modelo de adaptación propuesto por Sor Callista Roy. Se observó el comportamiento de una muestra de adolescentes de 15 a 19 años y la atención del personal de enfermería. Los hallazgos se basan en los cuatro modos de conceptualización del modelo utilizado: necesidades fisiológicas, autoimagen, dominio del rol e interdependencia y cómo la intervención de enfermería debe promover la adaptación en un periodo de salud-enfermedad.

Comportamiento de puerperios adolescentes y la intervención de enfermería basada en el Modelo de Callista Roy / Behaviour of puerpers adolescents and the intervention of infirmary based in the model of Callista Roy

Pretende analizar los comportamientos de adaptación manifestados por las puerperas primíparas adolescentes, entre las seis a las veinte cuatro horas del puerperio y la intervención de enfermería ofrecida durante ese período, utilizando el Modelo de Adaptación, propuesto por Sor Callista Roy. Observa el comportamiento de una muestra de adolescentes de 15 a 19 años y la atención proporcionada por el personal de enfermería, durante un período de tres semanas, en la Maternidad María Cantera de Remón del Hospital Santo Tomás. Analiza el contexto en cuatro capítulos: en el primer capítulo se expone la definición del problema, sus antecedentes, la justificación, el propósito, los objetivos y las limitaciones del estudio; en el segundo se desarrolla el marco teórico, que servirá de referencia para analizar e interpretar los hallazgos, esencialmente el modelo de Callista Roy donde la autora conceptualiza al ser humano como un ser bio-sico-social, en un entorno cambiante, el cual se adapta en cuatro modos: necesidades fisiológicas, autoimagen, dominio del rol e interdependencia y cómo la intervención de enfermería debe promover la adaptación del hombre en un estado de salud-enfermedad, hace referencia a algunas características bio-sico-sociales de la adolescente en el período pre-concepcional, en el embarazo y en el puerperio, relacionándolas con las cuatro formas de adaptación que propone el modelo; En el tercer capítulo explica la metodología utilizada en el desarrollo del estudio, ésta consiste en la revisión de expedientes, observación de los pacientes, intervención de enfermería, análisis de causales de los comportamientos negativos, procesamiento, análisis e interpretación de los datos obtenidos en la sala de puerperio de la Maternidad Maria Cantera de Remón. Explica que durante el puerperio, período que se inicia inmediatamente después del parto, las jóvenes presenta una serie de comportamientos, los cuales están condicionados por factores inherentes a la madre y al tipo de atención que recibe por parte del personal de salud, los cuales responden a un contexto socio-cultural que involucra tanto a la madre como al equipo de salud que proporciona la atención. Considera que las adolescentes por sus características propias que presentan en esta etapa de transición se encuentran más vulnerables a presentar conductas riesgosas para su salud, la del niño y que la atención que brinda el personal de enfermería se da, sin atender características especiales. Aclara