[Surgical treatment of a Dobermann pinscher with cervical spondylopathy]

The successful treatment of a Dobermann Pinscher affected with cervical spondylopathy by decompression of the intervertebral disc involved and fusion of the adjacent vertebrae is reported.

Unrecognized errors due to analog filtering of the brain-stem auditory evoked response

Analog filtering of the brain-stem auditory evoked response (BAER) and synthetic wave forms using steeply sloped filters are shown to produce significant distortion even when filter cut-off frequencies are well removed from the wave form spectrum. The degree of distortion is such that it may result in erroneous identification of peaks in the BAER. Reversal of the order of peaks may occur with high pass settings at only 1/4 the lowest constituent frequency. Filter effects were identified as a major source of cross-laboratory differences in BAERs recorded from laboratory rats. Filter transfer functions of a typical analog filter set were derived for both gain and phase as a function of frequency. Filtering of synthetic wave forms was used to elucidate and highlight distortion effects. A typical Long-Evans rat BAER wave form was spectrum analyzed and conclusions were drawn with respect to appropriate bandpass frequencies.

Neurophysiological consequences of acute exposure to methylpyridines

A series of neurophysiological tests was performed on Long-Evans hooded rats treated with either 2-, 3-, or 4-methylpyridine at dosages of 100 mg/kg, approximately one-half the ip LD50. The tests contained measures of sensory function (paired pulse flash evoked potentials, pattern reversal evoked potentials, and brainstem auditory evoked responses) and cerebral excitability (pentylenetetrazol seizures and hippocampal afterdischarges). In general, rats treated with 2- and 3-methylpyridine were more affected than those treated with 4-methylpyridine. The changes observed were in many ways similar to those seen following administration of depressant compounds: increased latency of evoked potentials and increased latency to PTZ seizures. Not all findings, however, were consistent with previously observed patterns of central nervous system depression.

Neurophysiological effects of 30 day chronic exposure to toluene in rats

Long-Evans hooded rats were exposed to 1000 ppm toluene or 0 ppm toluene 6 hr/day, 5 days/week for 30 days. Following removal from the exposure conditions (18-26 hr) flash-evoked potentials were recorded to paired light flashes and pentylenetetrazol (PTZ) seizure properties were examined. No alterations were found in the response to the first flash, but alterations in the recoverability of the nervous system were demonstrated by significant latency shifts in the response to the second of the paired flashes, using first flash latencies as covariates. No significant alterations were found in PTZ seizures. The data indicated that at these exposure levels toluene produced a small but significant alteration in brain function, even after toluene had been completely metabolized.

Mechanisms of bunyavirus virulence. Comparative pathogenesis of a virulent strain of La Crosse and an avirulent strain of Tahyna virus

To analyze mechanisms of virulence in the California serogroup bunyaviruses, the virulent La Crosse/original (LAC/original) strain was compared with the avirulent Tahyna/181-57 strain. In suckling mice, both viruses were lethal upon intracerebral injection but differed markedly in their neuroinvasiveness following subcutaneous injection; 20 and 20,000 plaque-forming units, respectively, were equivalent to 1 subcutaneous LD50. The sequential course of infection was followed after subcutaneous injection of 700 plaque-forming units; LAC/original replicated in striated muscle, caused a high titer plasma viremia, invaded the central nervous system, and killed all mice; the same dose of avirulent Tahyna/181-57 failed to replicate in extraneural tissues, did not invade the central nervous system, and caused no apparent illness. Immunofluorescent examination of peripheral and central nervous system tissues showed the same distinctions between virulent and avirulent viruses and pinpointed striated muscle as the major extraneural target of virulent LAC/original virus. Paradoxically, after intracerebral injection of suckling or adult mice, Tahyna/181-57 virus killed more quickly than LAC/original. This difference was correlated with replication differences; Tahyna/181-57 multiplied marginally faster in the brain than did LAC/original virus.

Mediastinal computed tomography in myasthenia gravis

Thirty-six of 119 patients with myasthenia gravis examined by computed tomography for possible thymic mass had a thymectomy. The computed tomographic findings were compared to the findings of chest x-ray and linear tomography and then correlated with the surgical histopathologic results. Computed tomography detected all cases of thymoma or thymic enlargement due to hyperplasia. Chest x-ray correctly demonstrated 50% of thymomas present while linear tomography demonstrated 88%. Computed tomography was not able to distinguish between enlargement due to thymoma or hyperplasia unless calcification was present. The role of computed tomography is detailed and discussed in relationship to the other diagnostic modalities.

[Magneto-implants in surgery of the motorsystem. A project (author's transl)]

The high quality material of permanent magnetos permits various applications to the surgery of the motor system. When designing artificial joints, for certain osteosyntheses and osteotomies, for the stimulation of growth at the epiphyses and in orthopedic techniques. Encouraging attempts at "magneto-medicine" exist in ophthalmology, urology and general surgery. We propose to test permanent magnets for attraction and separation in orthopedic and traumatic surgery.