Somatosensory evoked potentials in the assessment of peripheral neuropathies: Commented results of a survey among French-speaking practitioners and recommendations for practice.

BACKGROUND: Somatosensory evoked potentials (SSEPs) are increasingly performed for the assessment of peripheral neuropathies, but no practical guidelines have yet been established in this specific application. STUDY AIM: To determine the relevant indication criteria and optimal technical parameters for SSEP recording in peripheral neuropathy investigation. METHODS: A survey was conducted among the French-speaking practitioners with experience of SSEP recording in the context of peripheral neuropathies. The results of the survey were analyzed and discussed to provide recommendations for practice. RESULTS: SSEPs appear to be a second-line test when electroneuromyographic investigation is not sufficiently conclusive, providing complementary and valuable information on central and proximal peripheral conduction in the somatosensory pathways. CONCLUSIONS: Guidelines for a standardized recording protocol, including the various parameters to be measured, are proposed. CLINICAL RELEVANCE: We hope that these proposals will help to recognize the value of this technique in peripheral neuropathy assessment in clinical practice.

Nucleosome positioning and composition modulate in silico chromatin flexibility.

The dynamic organization of chromatin plays an essential role in the regulation of gene expression and in other fundamental cellular processes. The underlying physical basis of these activities lies in the sequential positioning, chemical composition, and intermolecular interactions of the nucleosomes-the familiar assemblies of ∼150 DNA base pairs and eight histone proteins-found on chromatin fibers. Here we introduce a mesoscale model of short nucleosomal arrays and a computational framework that make it possible to incorporate detailed structural features of DNA and histones in simulations of short chromatin constructs. We explore the effects of nucleosome positioning and the presence or absence of cationic N-terminal histone tails on the 'local' inter-nucleosomal interactions and the global deformations of the simulated chains. The correspondence between the predicted and observed effects of nucleosome composition and numbers on the long-range communication between the ends of designed nucleosome arrays lends credence to the model and to the molecular insights gleaned from the simulated structures. We also extract effective nucleosome-nucleosome potentials from the simulations and implement the potentials in a larger-scale computational treatment of regularly repeating chromatin fibers. Our results reveal a remarkable effect of nucleosome spacing on chromatin flexibility, with small changes in DNA linker length significantly altering the interactions of nucleosomes and the dimensions of the fiber as a whole. In addition, we find that these changes in nucleosome positioning influence the statistical properties of long chromatin constructs. That is, simulated chromatin fibers with the same number of nucleosomes exhibit polymeric behaviors ranging from Gaussian to worm-like, depending upon nucleosome spacing. These findings suggest that the physical and mechanical properties of chromatin can span a wide range of behaviors, depending on nucleosome positioning, and that care must be taken in the choice of models used to interpret the experimental properties of long chromatin fibers.

Attitudes and educational practices of obstetric providers regarding infant hepatitis B vaccination.

OBJECTIVE: To survey the current knowledge, attitudes, and practices of obstetric providers regarding the education of pregnant women about infant hepatitis B vaccination. METHODS: A questionnaire was mailed to 264 physicians providing obstetric services in San Francisco. Of these, 113 were confirmed to be providing prenatal care. RESULTS: Seventy-six obstetric providers returned completed questionnaires. Among eligible respondents, 79% believed that hepatitis B vaccine should be administered to all infants at birth, and 92% believed that it is feasible to educate all expectant mothers about infant hepatitis B vaccination. However, only 53% of respondents provided such education to all their pregnant patients. Only 23% provided education about other routine childhood immunizations. CONCLUSIONS: Obstetric providers in San Francisco are willing to educate pregnant patients about hepatitis B vaccination but are not always doing so. Providing education in a consistent manner may improve infant hepatitis B vaccination rates and may increase coverage with other childhood vaccines.

Expanding the donor pool: use of marginal donors for solid organ transplantation.

Organ transplantation has become a viable treatment for an increasing number of patients suffering from irreversible organ failure. In response to the steeply rising demand for transplantation, both the number of transplant centers and the number of patients on waiting lists have grown rapidly. Because organ donation has not kept pace with demand, each year a greater number of patients die while awaiting donor organs. (About 9% of all patients on the list in 1993 but not transplanted died. Death rates were highest, 19% and 16% respectively, for patients awaiting hearts and livers.) Among the factors contributing to the organ shortage are cultural and psychological barriers to donation and missed opportunities to request donation. An accompanying diminution in traumatic deaths of potential young donors has made older and other marginal, or higher-risk, donors the focus of studies on expansion of the donor pool. The studies reviewed herein evaluated donor risk factors such as age, disease (including infection), obesity, cold ischemia time, suboptimal organ function, and nontraumatic causes of death. Overall, broadened criteria for acceptable donor kidneys, hearts, and livers appear to lessen graft survival rates somewhat compared with rates for ideal donor organs. Nonetheless, use of higher-risk organs allows lifesaving transplants that could not otherwise be performed and results in acceptable prognoses for survival. Further research is needed to identify better tests for evaluating donor organs, provide longer-term follow-up of recipients of higher-risk organs, and develop alternative means to fill the donor-organ shortfall.

[Acute Trypanosoma brucei gambiense meningoencephalitis detected by papillary edema]. / Méningo-encéphalite aiguë à Typanosoma brucei gambiense révélée par un oedème papillaire.

A 26 year old woman, living in Brazzaville, was referred by her ophthalmologist about papillo-oedema. Neurological examination showed frontal syndrome and papillo-oedema without another sign of intracranial hypertension. Electroencephalogram revealed bilateral delta waves and bifrontal points. Significant inflammatory syndrome was noted. Cerebrospinal fluid examination showed trypanosomes with an elevated rate of protein and cells. Treatment by tetracosactide and eflornithine gave a good recovery. Authors are stressing the disconcerting feature of this clinical form. An urban from of the disease and the fight against african trypanosomiasis are also discussed.