Mitochondrial encephalopathy with lactic acidosis and stroke-like episodes in a Japanese child: Clinical, radiological and molecular genetic analysis

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes is a mitochondrial multisystem disorder. This disease has mainly been associated to the mitochondrial DNA mutation A3243G located in the tRNA Leucine gene. In this article, we report the clinical, radiological and molecular results of a 10 years old Child with the classical Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes phenotype. A 10 years old male Japanese child presented with recurrent episodes of headache, nausea and vomiting of 5 years duration and hyperlactic acidemia. These episodes were associated with motor weakness on the right side, with difficulties in language and memory and visual disturbance. Neurological examination revealed generalized muscle weakness with mild right sided hemiparesis. The Magnetic Resonance Imaging revealed infarct like lesions in the left occipital regions and the left medial temporal. The mitochondrial DNA mutations A3243G, T3271C and G13513A were tested using Polymerase Chain Reaction-Restriction Fragment Length  Polymorphism analysis and direct sequencing. The heteroplasmic A3243G mutation was detected in the blood of the patient and his mother. L-Arginine is reported to be beneficial for the patients and a preventive treatment was given in the form of arginine 500 mg twice per day

Phononic Crystals and Thermal Effects

In this work, we demonstrate a comprehensive theoretical study of one-dimensional perfect and defect phononic crystals. In our study, we investigate the elastic and shear waves with the influences of thermal effects. The numerical calculations based on the transfer matrix method (TMM) and Bloch theory are presented, where the TMM is obtained by applying the continuity conditions between two consecutive sub-cells. Also, we show that by introducing a defect layer in the perfect periodic structures (defect phononic crystals), we obtain localization modes within the band structure. These localized modes can be implemented in many applications such as impedance matching, collimation, and focusing in acoustic imaging applications. Then, we investigate the influences of the incident angle and material types on the number and intensity of the localized modes in both cases of perfect/defect crystals. In addition, we have observed that the temperature has a great effect on the wave localization phenomena in phononic band gap structures. Such effects can change the thermal properties of the PnCs structure such as thermal conductivity, and it can also control the thermal emission, which is contributed by phonons in many engineering structures

Mitochondrial DNA depletion syndrome presenting with ataxia and external ophthalmoplegia: Case report

The mitochondrial DNA depletion syndromes are autosomal recessive disorders characterized by decreased mitochondrial DNA copy number in affected tissues.Mutations in 2 genes involved in deoxyribonucleotide metabolism, the deoxyguanosine kinase gene and the thymidine kinase 2 gene, had been related to this syndrome. This study aims to describe the clinical, histochemical, biochemical and molecular diagnosis of one Egyptian pediatric patient with the myopathic form of mitochondrial depletion syndrome. The patient presented to Cairo University Pediatric Hospital with the clinical suspicion of mitochondrial encephalomyopathy. Histochemical and biochemical studies of the respiratory chain complexes were performed on the muscle biopsy specimen from the patient. Molecular diagnosis was done by quantitative radioactive Southern blot and sequencing analysis of the whole coding regions of the TK2 gene. Histochemical staining revealed cytochrome oxidase negative fibers and increased staining for succinate dehydrogenase. The activity of complex I was not detected and complex IV activity was about 46%of age matched controls. Southern blot analysis showed reduction of the mitochondrial/nuclear DNA ratio, the degree of depletion was around 30% of aged-matched controls. Sequencing analysis of the TK2 gene revealed no sequence variation. Targeted molecular diagnosis based on the biochemical analysis of the respiratory chain enzymes makes the molecular evaluation of mitochondrial disorders much easier. Involvement of other nuclear genes rather than TK2 gene in the pathogenesis of the myopathic form of mitochondrial depletion syndrome should be considered.Keywords: Mitochondrial; Nuclear; Sequencing; Depletion; Mutation

The development, implementation, and evaluation of a school volunteer program for Cowan Heights Elementary School, St. John's

The purpose of this project was to develop, implement, and evaluate a volunteer workers' program at Cowan Heights Elementary School, St. John's. -- The data for the project were drawn from (1) the writer’s personal experience in working with volunteers in the school for more than ten years, (2) a study of the literature related to volunteerism, and (3) the use of questionnaires to assess the volunteer workers' program. The value of the volunteer workers’ program was shown by administering questionnaires to volunteers, teachers, the Principal and a random sample of pupils from Cowan Heights Elementary School. The conclusions and recommendations are based on an analysis of these questionnaires, and the observations, interviews and comments of the people involved in the program. The volunteer program continues to function uninterrupted by this study and has been refined and improved as a result. -- The conclusions of the study seem clear: the volunteer program improves the services offered and increases the community's understanding of the school program. The small number of classroom teachers willing to use volunteers in their program suggests the professional's tendency to be somewhat ill at ease with volunteers, but further orientation and trust-building might eliminate much of the reluctance which now seems to exist. -- It will be shown in the course of this project that a volunteer program cannot be decided upon one day and implemented the next. To have a successful program requires motivation on the part of the principal, the teachers and the volunteers so that a team relationship is built up and an understanding established so that the pupils are the beneficiaries. -- The recommendations of this project are clear. The school personnel and the members of the community must develop a greater degree of trust in each other so that the needs of the primary participants - the students - are met in the most efficient way. School boards would be well advised to take advantage of volunteer help available to them to make this auxilary service to the school the best they can provide at no extra financial cost

One-dimensional phononic crystals that incorporate a defective piezoelectric/piezomagnetic as a new sensor

In this paper, we have studied the propagation and localization of acoustic waves in a one-dimensional (1D) phononic crystal at the effects of both electric and magnetic fields. We focused on the sensing and measuring the electric and magnetic fields by adjusting the position of the transmitted peak (defect mode) inside the two piezoelectric/piezomagnetic defect layers (0.7 PMN-0.3PT/Terfenol-D). The defect mode is shifted towards the lower frequencies by applying electric and magnetic fields and towards the higher frequencies by opposing the field’s direction. The bigger the value of the applied field is the greater movement in the peak position is. In addition, our results revealed that the magnetic field has a bigger influence than the electric field on the position of the defect mode. Moreover, we studied such movement of the defect mode position by applying the electric and magnetic field simultaneously. These results can be used to improve and enhance piezoelectric and piezomagnetic energy harvesters

Thermal properties of one-dimensional piezoelectric phononic crystal

By using the transfer matrix method, we theoretically studied the propagation of a longitudinal acoustic wave in a one-dimensional phononic crystal (PnC) that contains a piezoelectric material as a defect layer. A pass band can be generated and controlled in the middle of the band gap. The pass band position is tuned by applying an external electric field. The position of the pass band inside the band gap is tuned by the changing of temperature. We introduce a comparison between temperature effects on two piezoelectric materials, PZT-5H and 0.7 PMN-0.3PT inside a PnC structure. Moreover, the pass band is shifted towards high or low frequencies by temperature decrement or increment, respectively. The simulated results provide a valuable guidance for PnC applications such as acoustic switch and temperature sensor

Experimental and numerical evidence of using a Phononic membrane with the coupling of Fano resonant modes as a highly sensitive temperature sensor

In this article, we present numerically and experimentally a tunable phononic membrane as an efficient temperature sensor based on the generation of slow modes (sharp resonance modes) in microcavities. The Phononic membrane is periodically perforated with subwavelength slits (apertures) to produce tunable modes in these cavities (mode corresponding to a cavity resonance). By emerging the silicon membrane in water, a coupling effect between acoustic waves through the slits occurs, which leads to multiple-wave interferences like Fabry Perot resonators. Besides, this design could secure the phenomenon of ultrasonic opacity through the perforated silicon membrane. Where a deep and large attenuation band with a relative bandwidth of 31 % and at the central frequency of 0.9 MHz is observed in the amplitude transmission spectra of the phononic membrane. Secondly, by modifying the temperature of the water, the position of the bandwidth is tuned, since, we could achieve high sensitivity of 2400 Hz °C-1 for a temperature change of 10–20 °C, which is considered a promising result for many important applications such as temperature sensors and biosensors