Possible role of backpropagating action potentials in corticospinal neurons in I-wave periodicity following a TMS pulse

A single pulse of TMS or direct electric stimulation over M1 causes repetitive synchronized firing of corticospinal tract (CST) neurons. Two mechanisms for the repetitive firing have been proposed: a cascade of synaptic inputs to the pyramidal neurons and a single reverberating circuit of interneurons. Here, we propose another possibility in which bursting of CST neurons is produced by dendritic Ca2+-spikes. Backpropagation of the initial action potential (I1-wave) from the soma interacts with synaptic input in the dendrites to initiate a dendritic calcium spike. These Ca2+-spikes produce a burst of somatic action potentials that starts about 1.5 ms after the initial discharge of the neuron, which may produce the later I-waves

A New Classification System for Evaluating Patients with Severe Trauma Using B-type Natriuretic Peptide Levels and Estimated Glomerular Filtration Rate

Current systems for the evaluation of trauma severity are tedious and difficult to apply in an actual emergency setting. We aimed to develop and assess the accuracy of a more efficient severity evaluation system, termed the Ugawa classification, using brain-type natriuretic peptide (BNP) measurement and the estimated glomerular filtration rate (eGFR). Two-hundred trauma patients were divided into 2 groups using an eGFR cut-off value of 90ml/min/1.73m2 as an indicator of normal renal function and 2 additional groups according to whether the BNP values were greater or less than the age in years. This resulted in 4 subject groups with different combinations of eGFR and BNP. The mean SOFA score, injury severity scores (ISS), trauma and injury severity scores (TRISS), and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores of the groups were compared by Kruskal-Wallis test, and the mortality rate after 90 days was calculated. Significant intergroup differences were found in SOFA scores, ISS scores, and APACHE II-predicted mortality rates. Although no significant differences were found in the mortality rate after 90 days or TRISS-predicted mortality rate among the 4 groups, there was a trend toward increasing trauma severity from group 1 to 4. Thus, the Ugawa classification is as accurate as existing systems, has greater efficiency, and is user-friendly

Non-high-output cardiac failure in patients undergoing hemodialysis through an arteriovenous shunt

Background: Hemodialysis-related heart failure has been considered to be associated with excessive blood flow through the arteriovenous (AV) shunt used for vascular access. However, some patients undergoing dialysis have heart failure in the absence of an increase in cardiac output (CO) related to shunt blood-flow loading because the loading cannot be compensated for by increasing CO. This condition may be challenging to manage ; thus, early diagnosis is important. Methods and Results: Twelve patients (mean age, 71 years ; 9 men) with end-stage renal disease, dialysis-related heart failure, a high brain natriuretic peptide (BNP) level, and a mean New York Heart Association (NYHA) class of II underwent AV shunt closure. Their cardiac index (CI), pre- and post-dialysis BNP levels, and several cardiac variables were assessed pre- and postoperatively. All patients achieved relief of heart failure symptoms and a reduction in NYHA class after AV closure, but six patients had a postoperative increase in CI (the "non-high-output" cardiac failure group), whereas the other six had a decrease in CI (the "high-output" cardiac failure group). The high-output patients had greater improvements in BNP levels and most cardiac variables compared to the non-high-output group ; therefore, the heart failure in the non-high-output patients was considered more serious than that in the high-output group. Conclusions: The selection of effective strategies for treating dialysis-related heart failure may depend partly on identifying which patients have non-high-output failure. Such identification requires serial measurements of BNP levels and evaluations of cardiac variables other than the ejection fraction