Le traitement du signal en électromyographie: mise au point

Automatic analysis of electromyography (EMG) signals, first operated in 1950 with analogic machines, steeply expanded from 1980 when fast computers and worthwhile programs became available. On-line measurement of response area and latency, averaging of low amplitude waves, fast sorting of motor unit potential shape parameters, computation of the “jitter” between two muscle fibers, turns/amplitude and spectral analysis of interferential pattern records, are some examples of programs currently offered in modern EMG machines. Other techniques are still reserved for research purposes: scanning EMG, decomposition of nerve and muscle compound potentials, measurement of the threshold and firing rate of motor units, trace analysis using tracking models. Finally, the credit for artificial intelligence systems (knowledge based systems, fuzzy logic, neuronal networks) is still not clearly stated.     

Pitfalls in counselling: the craniosynostoses.

We describe three families to highlight the variability of expression and penetrance that can occur in the craniosynostoses. In two of the families, gene carriers were only identified in retrospect by looking at photographs of other family members. In the third family, identical twins were initially thought to be discordant for sagittal craniosynostosis until early skull x rays were examined and both were found to be affected. The dilemmas faced when counselling these families are discussed.     

Hyperpolarizing current of the Na/K ATPase contributes to the membrane polarization of the Purkinje cell in rat cerebellum

 The contribution of the Na/K ATPase (pump) current to the polarization of the Purkinje cell has been studied using slices of the rat cerebellum by blocking the pump with dihydro-ouabain (DHO) while recording the membrane potential with microelectrodes in the somata. From our recordings, it appeared that blocking the pump depolarized the Purkinje cells more rapidly than might be expected from shifts in Na⁺ and K⁺ concentrations, suggesting the removal of a hyperpolarizing current. Application of DHO, in the presence of tetrodotoxin (TTX), led to calcium spike firing and plateau-like discharges suggesting activation of voltage-dependent calcium channels in the dendrites. Adding 2 mM Co²⁺ to the medium did not prevent the depolarizations. Removing calcium from the bathing medium containing 2 mM Co²⁺ blocked the spiking activity but DHO application still produced a depolarization. Experiments to measure the current inhibited by DHO indicated that the Na/K pump supplies a constant current of 240 pA. Substitution of the sodium with choline produced a hyperpolarization, during which DHO had no effect on the membrane potential. Substitution of the sodium with lithium produced only a slowly developing depolarization. It is concluded that in the cerebellar Purkinje cell, a continuous sodium ion influx activates the pumps which produce a current that directly contributes to the membrane polarization. Possible pathways for this sodium influx are discussed. Received: 3 April 1997 / Received after revision and accepted: 12 May 1997     

Use of 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyl Tetrazolium Bromide for Rapid Detection of Rifampin-Resistant Mycobacterium tuberculosis

We describe a test which uses the ability of viable cells to reduce 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to detect resistance to a bactericidal drug, rifampin, in in vitro-cultured Mycobacterium tuberculosis. The assay shows a linear relationship between the number of viable bacteria and the ability to reduce MTT. Dead mycobacteria were unable to reduce MTT. Rifampin-sensitive M. bovis (BCG) and M. tuberculosis exposed to rifampin showed a rifampin concentration-dependent inhibition of the ability to reduce MTT, while the resistant strains were unaffected. The inhibition of MTT reduction after treatment with rifampin paralleled the reduction in the number of CFU. By using mixing experiments in which the population percentages of rifampin-sensitive and -resistant strains were varied, the assay could detect the presence of rifampin resistance in the mixture when at least 1% of the bacterial population was composed of drug-resistant strains. The assay is cheap, can be visually read, and requires less than 3 days to obtain susceptibility results. The total time required to obtain results, from the time sputum is received in the laboratory, is, in most cases, less than 4 to 5 weeks, which is the time required for primary culture of the bacteria. The MTT assay could, in combination with a test to detect resistance to isoniazid, be a cheap and rapid screening method for multidrug-resistant M. tuberculosis that is affordable even by low-income countries where tuberculosis is a major public health problem.     

Genetic linkage analysis identifies new proximal and distal flanking markers for the X-linked agammaglobulinemia gene locus, refining its localization in Xq22

Genetic linkage analysis has been instrumental in mapping thegene for X-linked agammaglobulinemia (XLA) to the proximal longarm of the human X chromosome, to Xq22. Due to the relativerarity of this disease the localization of the gene within Xq22has remained imprecise. We have investigated twenty-nine familiesaffected by XLA and have found no recombinants with the DXS178locus in over 30 informative meioses. DXS178 is now the mostreliable and informative locus for use in pre-natal diagnosisand carrier detection of XLA. In addition, we have identifiednew closely linked proximal and distal flanking markers forXLA, DXS442 and DXS101, respectively. These loci are separatedby 2cM, considerably reducing the extent of DNA within whichthe XLA locus can be contained. This will open up the way formore directed positional cloning efforts for the isolation ofthe XLA gene.     

Therapeutic drug monitoring of risperidone using a new, rapid HPLC method: reappraisal of interindividual variability factors

Because of the enormous gap between premarketing studies in physically healthy subjects and clinical practice in patients, the present study reconsidered interindividual variability factors affecting risperidone concentrations under routine therapeutic drug monitoring conditions. The study included 92 patients, 27% of whom were 70 years or older. The patients received risperidone orally (dose range, 0.5-11 mg per day) and had concentrations of risperidone and the active metabolite 9-hydroxyrisperidone measured at steady state by a new, rapid, and sensitive method of high-performance liquid chromatography (HPLC). After normalization to a dose of 4 mg/day, median concentrations were 2.9 ng/ml (80% range, 0.9-27.9 ng/ml) for the parent compound and 24.1 ng/ml (80% range, 12.0-57.6 ng/ml) for the metabolite. When considering linear regression models, age was identified as a major source of interindividual variability, with expected increases of 340% and 220% for concentrations of parent compound and metabolite, with age increasing from 20 to 80 years. Body weight provided an additional significant contribution to the variability of 9-hydroxyrisperidone concentration, a 20-kg higher body weight associated with a concentration decrease of 23%. Serotonin-specific reuptake inhibitor (SSRI) comedication (fluoxetine, two patients; citalopram, two patients; paroxetine, one patient; fluvoxamine, one patient) was significantly associated with 4.6-fold higher concentrations of parent compound, in keeping with an inhibitory action on CYP2D6 enzyme. Significantly higher concentrations of 9-hydroxy-risperidone (+ 29%) were also observed in the 17 patients with biperiden comedication. Therapeutic drug monitoring data, collected in patients representative of the population for which the drug was intended, allowed us to quantify the dose reduction needed in elderly patients and thus provided valuable information in addition to the one collected during premarketing studies performed with strict inclusion and exclusion criteria.     

精神发育迟滞患儿及其父母染色体脆裂性的遗传学分析

选择智力低下患儿及其父母共20个核心家庭,就4个有意义的c-fra的表达及遗传性进行了进一步的研究。结果是低叶酸培养,染色体的平均断裂频率是16.8641%,加叶酸培养,染色体的断裂频率2.9057%,4个c-fra的表达频率及表达阳性率男女有显著差别,其断裂占染色体总断裂的35.62%,未检出三射体。     

Bacteraemia among severely malnourished children in jimma university hospital, ethiopia

Background

Sever acute malnutrition severely suppresses every component of the immune system leading to increased susceptibility and severity to infection. However, symptoms and signs of infections are often unapparent making prompt clinical diagnosis and early treatment very difficult. The aim of the study was to determine the magnitude of bacteraemia and antimicrobial sensitivity among severely malnourished children.

Methods

Severely malnourished children admitted in Jimma University Specialized Hospital were enrolled between October, 2009 to May, 2010. Blood samples were collected, processed and bacterial isolates were identified using standard bacteriological procedures. Then, antibiotic susceptibility pattern of the isolates was determined by using Kirby-Bauer technique.

Results

Bacteraemia was seen in 35 (20.6%) of the 170 study subjects. There were a total of 35 bacterial isolates, Gram positive bacteria constitute 24(68.6%) of the isolates, where Staphylococcus aureus was the leading Gram positive isolate while Klebsiella species were the dominant Gram negative isolates. Twelve (7.1%) children died and 4 (33.3%) of them had bacteraemia. While susceptibility was more than 80% to Gentamicin, Ciprofloxacin and Ceftriaxone, increased level of resistance was documented to commonly used antibiotics, such as Amoxycillin, Co-trimoxazole and Chloramphenicol.

Conclusion

High prevalence of bacteraemia with predominating Gram positive isolates and increased level of resistance to commonly used antibiotics was shown among severely malnourished children in Jimma. Further studies are required to revise the current guideline for antibiotic choice.     

一个罕见的染色体畸变家系

报告1例首次发现的染色体异常核型家系,此家系2例患者为3号染色体部分单体,10号染色体部份三体。3例为3号染色体和10号染色体相互易位携带者。