Voltage-sensitive potassium ion channels are essential for life, but the molecular basis of their ion conduction is not well understood. In particular, the impact of ion concentration on ion conduction has not been fully studied. We performed several micro-second molecular dynamics simulations of the pore domain of the Kv1.2 potassium channel in KCl solution at four different ion concentrations...

Electromyographic single motor unit recordings were used to study the axonal conduction velocity and the axonal refractory period of 60 motor units in patients with severe motor neuron disease. Eighteen per cent of the motor units had abnormally low axonal conduction velocity probably due to secondary degenerative changes. Thirty-two per cent of the motor units had abnormally long axonal refrac...

Conduction and dielectric behavior of Sr0.97(Ti12xFex)O32d solid solutions were studied. The temperature dependence of the dc conductivity with s}A exp(2BT) obtained, indicated a variable-range hopping mechanism. A low-frequency dielectric relaxation was also observed. The activation energy for the variablerange hopping conduction is slightly higher than that for dielectric relaxation, suggesti...

Resistivities of heavy-fermion insulators typically saturate below a characteristic temperature $T^*$. For some, metallic surface states, potentially from non-trivial bulk topology, are likely source residual conduction. Here, we establish an alternative mechanism: At low temperature, in addition to the charge gap, scattering rate turns into relevant energy scale, invalidating semiclassical Bol...

BACKGROUND Paroxysmal atrioventricular block (P-AVB) is a well-known cause of syncope; however, its underlying mechanism is difficult to determine. This study aimed to evaluate a new ECG index, the "vagal score (VS)," to determine the mechanism of P-AVB. METHODS We evaluated the VS in 20 patients with P-AVB (13 men, 7 women; aged 25-78 years [mean, 59.3 years]). The VS was developed by assign...

The mechanism of ion conduction by potassium channels is one of the central issues in physiology. In particular, it is still unclear how the ion concentration and the membrane voltage drive ion conduction. We have investigated the dynamics of the ion conduction processes in the Kv1.2 pore domain, by molecular dynamics (MD) simulations with several different voltages and ion concentrations. By f...

PURPOSE To describe the effect of carpal tunnel release (CTR) on typing performance. METHODS We prospectively studied 27 patients undergoing open CTR. Patient demographics and clinical characteristics including nerve conduction studies, electromyography results, and duration of symptoms were collected. Before surgery and at 8 time points after surgery, ranging from 1 to 12 weeks, typing perfo...

In diabetic animals, reduced endoneurial perfusion and oxygen content have been linked to neuropathic abnormalities and might be amenable to pharmacological manipulation. In streptozotocin-induced diabetic rats, we studied the influence of guanethidine adrenergic sympathectomy, indomethacin treatment and a combined strategy on: serial in vivo motor and sensory conduction, resistance to ischemic...

Interruption of periodic wave propagation by the nucleation and subsequent disintegration of spiral waves is thought to mediate the transition from normal sinus rhythm to ventricular fibrillation. This sequence of events may be precipitated by a period doubling bifurcation, manifest as a beat-to-beat alternation, or alternans, of cardiac action potential duration and conduction velocity. How al...