Pylon fractures of the ankle: a distinct clinical and radiologic entity

Pylon fractures are a distinct clinical and radiologic entity that should not be confused with trimalleolar fractures. Radiographic and clinical comparison of 20 surgically documented pylon and ten trimalleolar fractures revealed four major features of pylon fractures distinguishing them from trimalleolar fractures: (a) the presence of profound distal-tibial comminution, (b) intra-articular extension of tibial fractures through the dome of the plafond, (c) the presence of a fractured talus, and (d) anatomic relationship of the lateral malleolus to the talus at the level of the ankle mortise. With use of clinical history in addition to plain radiography, pluridirectional tomography, and computed tomography, these two fractures can be clearly separated. This distinction carries important surgical and prognostic implications.     

False ankylosis of the temporomandibular joint after otologic and neurotologic surgery

Two cases of ankylosis of the temporomandibular joint (TM) after otologic and neurotologic surgery involving an approach through the temporal fossa are reported. The etiology is believed to be that of fibrous contracture within the temporalis muscle, which is incised during the procedure. If the possibility of this rare complication is anticipated, the immediate instigation of prophylactic jaw exercises and forced opening with tongue depressors can significantly limit morbidity. If the condition is allowed to become established, then surgical correction by coronoidectomy may be necessary.     

Cardiac electrophysiologic and inotropic actions of new and potent methanesulfonanilide class III antiarrhythmic agents in anesthetized dogs.

The effects of cumulative intravenous (i.v.) administration of potent and selective methanesulfonanilide class III antiarrhythmic agents on cardiac electrophysiologic and hemodynamic parameters were compared with those of D-sotalol in chloralose-anesthetized dogs. The new class III agents tested were E-4031 [1-(2-(6-methyl-2-pyridyl)ethyl)-(4-methanesulfonamidobenzoyl)pipe ridine]; UK-66,914 [N-(4-(1-hydroxy-2-(4-(4-pyridinyl)-1-piperazinyl)ethyl)phenyl) methanesulfonamide], and UK-68,798 [1-(4-methanesulfonamidophenoxy)-2-(N- (4-methanesulfonamidophenethyl)-N-methylamino)ethane]. The class III agents produced significant and dose-dependent increases in ventricular refractoriness, with effective doses required to increase ventricular relative refractory period 20 ms above baseline (ED20, micrograms/kg i.v., with 95% confidence limits) of 5.2 (4.2-6.6) for UK-68,798, 17 (13-23) for E-4031, 75 (58-99) for UK-66,914, and 3,700 (2,600-5,800) for D-sotalol. Significant increases in the electrocardiographic QT and QTc intervals paralleled the increases in ventricular refractoriness for the four class III agents. Significant increases in left ventricular (LV) + dP/dt also paralleled increases in ventricular refractoriness and QT intervals for E-4031 (10-1,000 micrograms/kg i.v.), UK-66,914 (100-1,000 micrograms/kg i.v.), and UK-68,798 (30-1,000 micrograms/kg i.v.), but not for D-sotalol. No concomitant alterations in LV-dP/dt were observed for the new and potent methanesulfonanilide class III agents, resulting in significant increases in the ratio of LV + dP/dt/-dP/dt for E-4031, UK-66,914, and UK-68,798. Potent and selective methanesulfonanilide class III agents therefore may augment cardiac contractility in addition to prolonging ventricular refractoriness.     

Metabolism and binding to cellular macromolecules of a series of hydrocarbons by mouse embryo cells in culture

A series of eight tritium-labelled polycyclic hydrocarbons were incubated in the presence of monolayer cultures of primary mouse embryo cells, and the time-course of their metabolism to water-soluble derivatives was studied. All the hydrocarbons, both carcinogenic and non-carcinogenic, were metabolized at approximately the same rate when a low concentration of the order of 0.05 μM was used. The binding of the various hydrocarbons to cellular DNA, RNA and protein was determined and a “binding index” calculated, i.e., the extent of reaction of the hydrocarbon with the particular macromolecule resulting from the metabolism of 1 mμmole of hydrocarbon per ml of medium to which the cells were exposed. While no very significant difference between the various hydrocarbons was found for the protein binding index, the DNA and RNA binding indices divided the compounds into two groups. One group with a high binding index consisted of potent carcinogens while the other group had much lower (one tenth) values for the binding index. With the exception of dibenz[a, h]anthracene, this latter group consisted of non-carcinogens.