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Biomedical subjects

G W Sypert

Publications and source records attributed to G W Sypert.

At least 73 records · Page 4Linked to original sources
PubMed1977

Korsakoff's syndrome resulting from bilateral fornix lesions.

A patient with a well-circumscribed neoplasm, which destroyed the posterior fornix bilaterally, developed a profound disturbance of recent memory. Unlike previously reported patients who had undergone anterior fornix sections and whose memories were not severely disturbed, this patient's posteriorly located lesion may have cut off hippocampal input into the mamillary bodies and the dorsomesial nucleus, thereby producing a severe amnestic state.

Adult↗
PubMed1976

Fast and slow pyramidal tract neurons: an intracellular analysis of their contrasting repetitive firing properties in the cat.

1. Intracellular recordings were made from an estimated 500 neurons in the sensorimotor cortex of barbiturate-anesthetized cats. Of those which were antidromically identified from the medullary pyramids, 70 were selected which also exhibited steady repetitive firing to steps of current injected through the recording electrode; 81% were "fast" (conduction velocity greater than 20 m/s) and 19% were "slow". 2. As shown by earlier workers, the spike duration is a function of conduction velocity; a spike duration of 1.0 ms is the dividing line between fast and slow. 3. Of the 57 fast pyramidal tract neurons (PTNS), 14 exhibited double spikes during otherwise rhythmic firing patterns to a step of injected current. These very short interspike intervals (usually 1.5-2.5 ms) were first seen interspersed in a rhythmic discharge (e.g., 50-ms intervals) but, with further increases in current strength, would come to dominate the firing pattern; e.g., double spikes every 40 ms. Further increases in current would typically shorten only the long intervals; e.g., 40-30 ms, but some fast PTNS developed triple spikes, etc. 4. The extra spike appears to arise from a large hump which follows most spikes in fast PTNS; while this humplike "depolarising after-potential" can also be seen in slow PTNS, it is small. Extra spikes were seen only in fast PTNS with large postspike humps; in perhaps half of the fast PTNS, extra spikes probably contributed to "adaptation." 5. Slow PTNS often had frequency-current curves which were not repeatable; a "hysteresis" phenomenon could often be seen, where the proportionality constant relating current to firing rate decreased following high firing rates. 6. The B spike was distinguishable from the A spike in differentiated antidromic spikes in 77% of the slow PTNS, in only 14% of the fast PTNS which later exhibited double spikes during current-induced repetitive firing, and in 53% of the other fast PTNS. 7. The antidromic spike heights of doublet PTNS were not significantly different from those of other repetitively firing PTNS.

Animals↗
PubMed1976

A technique for early Pantopaque myelography in cervical spinal cord injuries.

A simple, reliable method for early Pantopaque myelography in patients with traumatic injuries of the cervical spinal cord is presented. Myelography is accomplished with the patient prone on a Stryker frame after vertebral reduction and alignment have been achieved with axial skeletal traction. A lateral C1-2 spinal puncture and a portable ""C-arm'' image intensifier with televised fluoroscopy are used. There have been no complications and no occurrences of vertebral re-dislocation with this technique.

Humans↗
PubMed1976

Giant aneurysm of the middle cerebral artery.

A case of a giant aneurysm of the middle cerebral artery, (4.5 X 4.5 X 9.5 CM) presenting as a mass lesion, which was successfully excised is described. This case is compared to the few previous accounts of giant aneurysms of the middle cerebral artery larger than 3 cm in diameter.

Humans↗
PubMed1975

Cerebellar infarction. A clinicopathological study.

The clinical and pathological features of 28 fatal cases of acute uncomplicated massive cerebellar infarction are reviewed. Although infarcts may involve any portion of the cerebellum, they predominantly involve the posteroinferior half of one cerebellar hemisphere. The frequency of acute uncomplicated fatal cerebellar infarction is much greater than previously appreciated, approximating that of acute fatal cerebellar hemorrhage. All patients were past middle age. Atherosclerosis and acute vertebral artery occlusion were the most common etiological factors. The onset was sudden in most cases, with vomiting, dizziness, vertigo, and cerebellar dysfunction. All patients died with progressive brain stem dysfunction and medullary respiratory failure secondary to compression by a swollen cerebellum. Death usually occurred between the third and sixth days following the onset of symptoms, but only six to 30 hours after the onset of obtundation; therefore, decompressive therapy must be instituted promptly.

Acute Disease↗