Motor-Evoked Potentials for Early Individual Elements of an Action Sequence During Planning Reflect Parallel Activation Processes.

Several computational models make predictions about the activation states of individual elements of an action sequence during planning and execution; however, the neural mechanisms of action planning are still poorly understood. Simple chaining models predict that only the first response in an action sequence should be active during planning. Conversely, some parallel activation models suggest that during planning, a serial inhibition process places the individual elements of the action into a serial order across a winner-takes-all competitive choice gradient in which earlier responses are more active, and hence likely to be selected for execution compared with later responses. We triggered transcranial magnetic stimulation pulses at 200 or 400 ms after the onset of a five-letter word, in which all but one response was planned and typed with the left hand, except for a single letter which required a right index finger response exclusively at one of five serial positions. We measured the resulting motor-evoked potentials at the right index finger as a marker for the activation state of that planned response. We observed no difference in motor-evoked potential amplitude across any serial position when a right index finger response was planned at 200 ms after the onset of the word; however, we observed a graded pattern of activation at 400 ms, with earlier positions that required a right index finger response showing greater motor-evoked potentials amplitude compared with later positions. These findings provide empirical support for competitive queuing computational models of action planning.

Late-onset BK viral nephropathy in a kidney transplant recipient.

BK polyoma viral infection occurs as an asymptomatic infection in a high proportion of normal hosts without obvious sequelae. In the kidney transplant population, the virus is reactivated because of reduced immunity and, if not appropriately managed, can lead to BK viral nephropathy, which has emerged as a common cause of acute kidney injury and progressive chronic kidney disease in renal transplant recipients. BK viremia almost always occurs during the first 2 years after transplantation, when immunosuppressive therapy is high, or at other periods when immunosuppression is intensified. BK viremia is now detected by routine screening of transplant patients for the first few years, and BK viral nephropathy is considered to be high in the differential diagnosis of acute kidney injury in recently transplanted patients. We report a case of BK viral nephropathy developing 10 years after transplantation and present the challenges of managing advanced disease.

Thrombolytic therapy in acute coronary thrombosis.

Thrombolytic agents administered intravenously have been shown to have a salutary effect in the early management of acute myocardial infarction. However, a debate still is pending over the definite choice of an ideal thrombolytic agent. In our 83-bed community hospital, from January 1986 to September 1988, we treated 19 patients (n = 19) with acute myocardial infarction (average one patient every six weeks) with either intravenous streptokinase (IV STK) or intravenous tissue plasminogen (IV TPA) with a mean follow-up of 20.2 months. We compared both groups in terms of clinical reperfusion, morbidity and mortality, cost-effectiveness and long-term functional disability. Our results showed that most patients received their respective agents within four hours of the onset of chest pain (81% in the STK group, n = 11, versus 75% of the tPA group, n = 8). In the STK group, 90.9% showed clinical evidence of reperfusion compared to 87.5% in the TPA one, the difference not being statistically significant. Two patients in the STK group developed a treatable bradycardia, and one showed a junctional rhythm that was corrected. One patient in the TPA subset encountered a reversible ventricular tachycardia. However, we didn't note any bleeding complication in either group.