Helicobacter pylori gastric infections in children

OBJECTIVES: Numerous reports have established the association of Helicobacter pylori and recurrent abdominal pain in children. We investigated the clinical, bacteriological and therapeutic features of our patients seen over a 1 year period. METHODS: We investigated 121 children during 1992 in Hospital Saint Vincent-de-Paul, Paris. At endoscopy, biopsies were taken and sent for histology and bacteriology and urease testing. A decision regarding treatment by amoxicillin and metronidazol was made after positive results of bacteriology and/or histology. RESULTS: Heliobacter pylori was found in 47 antral biopsies after pathology examination with Giemsa staining alone 16 times, bacterial culture 9 times and both methods 22 times. Abdominal pain was the prominent symptom, occurring in 35.5% of Helicobacter pylori+patients. In 25 of the positive negative patients, a nodular gastritis was observed (53.1%) and in 27.6% of them a weight loss or a delay in weight gain. Few patients became after combined treatment with amoxicillin and metronidazol whereas eradication rates after triple therapy with amoxicillin-metronidazol and H2 antagonist or proton pump blocker were higher. CONCLUSION: Helicobacter pylori related gastritis is a common cause of abdominal complaints in children. The most common symptom is recurrent abdominal pain. Antral nodularity is a peculiar endoscopic finding in children. Two-drug therapy associating amoxicillin-metronidazol is often ineffective to eradicate the bacteria whereas eradication rates after triple therapy amoxicillin-metronidazol and H2 antagonist or proton pump blocker are higher.     

Angiotensin II receptor type 1 mRNA is upregulated in atria of patients with end-stage heart failure

There is increasing evidence that pathological changes in the myocardium during chronic heart failure (CHF) are partly regulated through the activation of the renin-angiotensin system (RAS), an effect mediated by the angiotensin II type 1 receptor (AT1R). We examined the expression of cardiac AT1R mRNA in normal (atria, n=7; ventricle, n=3) and end-stage CHF human hearts (atria, n=8; ventricle, n=14). Tissue was snap-frozen immediately after explantation during orthotopic cardiac transplantation; control specimens were obtained from healthy donor hearts rejected for technical reasons. Northern blots of purified total mRNA from each tissue were hybridized with a random primed radiolabeled probe for the coding sequence of AT1R. Stringent conditions were used for both hybridization (5X SSC, 65 degrees C) and washing (0.5X SSC, 0.1% SDS, 65 degrees C) of the membrane. Left and right atrial tissue showed low levels of AT1R mRNA expression in the controls, with statistically significant upregulation of expression in tissue from pathological hearts; CHF atria 1.28+/-0.86 optical density (OD) units, control atria 0.56+/-0.31 OD units, P=0.05 (mean+/-s.d.). There were undetectable levels in ventricles from either control (2/2) or dilated hearts (7/7). The results were independent of the etiology of the heart failure and suggest that increased levels of atrial AT1R mRNA may occur in response to elevated atrial pressures in heart failure.     

Evaluation of sport injuries in children and adolescents

Dengue type 2 virus (DV)-induced cytotoxic factor (CF) is capable of reproducing various pathological lesions in mice that are seen in human dengue. The present study was undertaken to investigate the protective effect of active immunization of mice with CF. Mice were immunized with 5 microgram of CF and prevention of CF-induced increase in capillary permeability and damage to the blood-brain barrier were studied at weekly intervals, up to 48 weeks, by challenging with 3 microgram of CF. Maximum protection against increase in capillary permeability and damage to the blood-brain barrier was observed in week 4 after immunization. A breakthrough in the protection occurred with higher doses of CF in a dose-dependent manner. Challenge with a lethal intracerebral (i.c.) dose of DV showed significantly prolonged mean survival time and delayed onset of symptoms of sickness in the immunized mice compared with the normal mice, but the titre of the virus in the brain was similar in the two groups. On i.p. challenge with the virus the protection against damage to the blood-brain barrier was 86 +/- 7% at week 4 and 17 +/- 4% at week 26 after immunization. Sera obtained from the immunized mice showed the presence of CF-specific antibodies by ELISA, Western blot, and by neutralization of the cytotoxic activity of CF in vitro. The present study describes successful prevention of a cytokine-induced pathology by specific active immunization.     

Circulating Monocyte Subsets and Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR), as an alternative to open heart surgery, has revolutionized the treatment of severe aortic valve stenosis (AVS), the most common valvular disorder in the elderly. AVS is now considered a form of atherosclerosis and, like the latter, partly of inflammatory origin. Patients with high-grade AVS have a highly disturbed blood flow associated with high levels of shear stress. The immediate reopening of the valve during TAVR leads to a sudden restoration of a normal blood flow hemodynamic. Despite its good prognosis for patients, TAVR remains associated with bleeding or thrombotic postprocedural complications, involving mechanisms that are still poorly understood. Many studies report the close link between blood coagulation and inflammation, termed thromboinflammation, including monocytes as a major actor. The TAVR procedure represents a unique opportunity to study the influence of shear stress on human monocytes, key mediators of inflammation and hemostasis processes. The purpose of this study was to conduct a review of the literature to provide a comprehensive overview of the impact of TAVR on monocyte phenotype and subset repartition and the association of these parameters with the clinical outcomes of patients with severe AVS who underwent TAVR.     

Investigations on junction temperature estimation based on junction voltage measurements

Reliability and ageing tests on power semiconductor devices require estimation of junction temperatures in order to control thermal stresses and monitor failure criteria. For this purpose, thermo-electrical parameters, such as voltage forward drop dependence with temperature are usually carried out in low injection level. Nevertheless, it is still difficult to evaluate the limits of such exploitation. An analytical model has been developed and validated by experimental measurements in order to evaluate self-heating effects and to understand high temperature effects. This model should also allow to highlight the role of some physical parameters in the voltage–temperature dependence and to clarify such thermal calibration.     

Optimization of wire connections design for power electronics

In automotive power electronics, low cost and reliability requirements both demand to optimize each part of the package in order to increase its life time during use. The wire bonding breakage accounts for one of the most common failures observed on power modules. In particular, the heel crack mechanism, mainly due to Joule self-heating, can occur in the module, leading to its death. Thus, the wire geometry design has to be set up to maximize its endurance. This paper presents an analytical method able to predict the optimal wire length regarding a wire displacement criterion. Finally, comparisons between experimental results and predictions of the analytical model are given.     

Deployable Structures Based on Buckling of Curved Beams Upon a Rotational Input

Inspired by the recent success of buckling-induced reconfigurable structures, a new class of deployable systems that harness buckling of curved beams upon a rotational input is proposed. First, experimental and numerical methods are combined to investigate the influence of the beam's geometric parameters on its non-linear response. Then, it is shown that a wide range of deployable architectures can be realized by combining curved beams. Finally, the proposed principles are used to build deployable furniture such as tables and lamp shades that are flat/compact for transportation and storage, require simple or no assembly, and can be expanded by applying a simple rotational input.     

Low-loss InGaAsP/InP submicron optical waveguides fabricated by ICP etching

The fabrication and characterisation of low-loss InGaAsP/InP optical submicron waveguides made with ICP etching is reported. Their width ranges from 0.2 to 2 /spl mu/m. For the 0.5 /spl mu/m width, the propagation losses at /spl lambda/=1.55 /spl mu/m as low as 4.2 dB/mm have been measured.     

A new methodology for the identification of ball bond degradation during high-temperature aging tests on devices in standard plastic packages

We describe a new methodology for the “in situ” identification of wire-bond degradation at early stages during high-temperature aging tests on devices with standard plastic packages. This methodology is based on the measurement of the changes in wire bond resistance, which is deduced from the I(V) characteristics of the ESD protection diodes on each contact pad of the circuit. In a first stage, the measurement procedure is described, with emphasis on the initial temperature calibration. This procedure allows for an “in situ” measurement sequence, where the packages stay in the aging chamber, at elevated temperature, during the electrical tests on the pad connections performed at different aging durations. By following accurately the package temperature, using a thermocouple, it is possible to correct for slight changes and thus get a reliable I–V measurement for each interconnection. In the second stage, the aging test results are described, showing the evolution of each individual interconnection. We were able to identify the onset of wire-bond degradation through the progressive increase of their resistance. To allow for better determination of the degradation process, once an increase in wire bond resistance was detected, complete I(V) curves were recorded at the pin(s) of interest. For each pin of a TQFP64 package, the tests were performed at least twice a day, with increased density when initial failure is detected (one complete measurement every 3 h). This strategy allowed for the detection of different behaviors on the wire bonds: good ball bonds (i.e. ball bonds with no change in their resistance), ball bond with intermittent opens (these ball bonds are in the process of degradation, and thermo-mechanical stresses induced in the resin by very small temperature changes are sufficient to open or close the circuits) and completely destroyed ball bonds, for which the resistance stays in an “high” level. This approach to wire-bond degradation in plastic packages is very powerful in terms of the number of interconnections which can be followed “in real time” and especially has the advantage, over other classical approaches, that the devices under test stay operational, contrary to what occurs with other types of destructive testing. These electrical test results are compared with metallographic investigations performed after a series of mechanical tests on the ball bonds (wire pull/ball shear tests) on a set of identical devices which undergone exactly the same High Temperature Storage (HTS) aging for 2000 h at 165 °C.     

Investigation of the heel crack mechanism in Al connections for power electronics modules

In power electronic packages, one of the main limiting factors for the module reliability stems from failure of the electrical interconnection which ensures the contact between the chip and the lead frame. The aim of this work is to model, using FEM and some analytical developments, the interconnection heel crack mechanism appearing in service. The forming process impact is particularly evaluated and it is established that the initial residual stresses contribute to limit the wire/ribbon life time.