Arterial peculiarities of the thoracolumbar spinal cord in rabbit.

The aim of this study was to investigate the arterial blood supply of the thoracolumbar spinal cord in rabbit. The study was carried out on twenty adult New Zealand white rabbits. Ten rabbits were used in the corrosion technique and ten rabbits in the dissection technique. After the killing, the vascular network was perfused with saline. Batson's corrosion casting kit no. 17 © was used as a casting medium. After polymerisation of the medium, in ten rabbits the maceration was carried out in KOH solution, and in ten other rabbits, formaldehyde was injected by the dissection technique into the vertebral canal. We found high variability of segmental arteries supplying blood to the spinal cord. There are 12 intercostal arteries and 1 costo-abdominal artery. Dorsal branches arising from the dorsal surface of the aorta thoracica were found as follows: in 70% of the cases, 9 pairs were present; in 20% of the cases 8 pairs; and in 10% of the cases 10 pairs. The paired arteriae lumbales were present in 6 pairs in 90% of the cases and in 5 pairs in 10% of the cases. On the dorsal surface of spinal cord, we found two irregular longitudinal arteries in 70% of the cases, no longitudinal arteries in 20% of the cases and three irregular longitudinal arteries in 10% of the cases receiving dorsal branches of rami spinales. Among the dorsal branches observed in the thoracic region, 60.5% were left-sided, 39.5% right-sided and in the lumbar region, 52.5% were left-sided and 47.5% right-sided.

Effect of Tanakan on postischemic activity of protein synthesis machinery in the rat brain.

A growing body of evidence supports the role of free radicals in triggering the functional and metabolic disturbances following transient cerebral ischemia. This study was designed to evaluate whether the extent of reperfusion-induced inhibition of protein synthesis initiation as well as tissue injury can be reduced by Tanakan (Ginkgo biloba extract, EGb 761) (Beaufour-Ipsen Industrie). Rats received Tanakan in the dose of 40 mg/kg/day for 7 days before surgical intervention. Transient forebrain ischemia was induced by 4-vessel occlusion. Rats were subjected to 20 min of ischemia followed by 30 min, 4 h or 7 days of reperfusion. Protein synthesis rate, reinitiation ability and neurodegeneration in the frontal cortex and hippocampus were measured by the incorporation of radioactively labelled leucine into polypeptide chains in postmitochondrial supernatants and by Fluoro-Jade B staining. The protective effect was observed, concerning both the protein synthesis and the number of surviving neurons, in the Tanakan-treated groups. Tanakan significantly reduced the ischemia/reperfusion-induced inhibition of translation in the neocortex as well as in the highly sensitive hippocampus. Our results indicate that free radicals play an important role in the development of reperfusion-induced injury, and the treatment of ischemic and reperfused brain with free radical scavengers may reduce the severity of reperfusion damage.

[Selective vulnerability of neuronal injury after experimental heart arrest]. / Selektívna zranitel'nost neurónov po experimentálnom zastavení srdca.

The study was aimed at the analysis of vulnerability of the olfactory bulb neurons in dogs after experimental heart arrest lasting for 15 minutes and recirculation lasting for 1 hour. By means of the Nauta degenerative neurohistologic method the reactions of individual types of nerve cells in the olfactory bulb were investigated. Nauta-positive granules were observed in the cytoplasm of the mitral and tufted cells of the olfactory bulb, which are of dopaminergic character. The granulations were present in the cellular areas which are rich in Nissl substance. The granular and short-axon cells of GABA-ergic character which contain a small amount of Nissl granules lack the Nauta-positive granules. Similarly, the Nauta-positive granules were absent in the axon hillock of mitral cells which under normal conditions do not contain the Nissl substance. These results justify the conclusion that ischemia lasting for 15 minutes and one-hour recirculation primarily affect the excitatory neurons rich in the Nissl substance. (Fig. 4, Ref. 16.).

Unusual type of ischemically induced synaptic degeneration studied by Hicks method.

This study describes the degenerating axonal termination and filamentous synaptic degeneration after 30 minutes spinal cord ischemia followed by 3 days survival using Hicks neurofibrillar impregnation. From laminoarchitectonic point of view a clear evidence was gained supporting the original description obtained by Nauta method. The majority of degenerated boutons revealed by Hicks method was found in the deep layers of the dorsal horn and then with increasing density in the intermediate zone and partly in the neuropil of the anterior horn. These results confirm the ability of Hicks method as a reliable tool in systematic research of the ischemically damaged synaptic contacts.

Early neurohistopathological changes of canine lumbosacral spinal cord segments in ischemia-reperfusion-induced paraplegia.

Mapping the canine lumbosacral spinal cord neurons damaged by ischemia-reperfusion after high thoracic aorta ligation was performed using the Nauta degenerating method. Highly Nauta-positive perikarya of the long ascending projection systems in the 4th to 6th dorsal layer, interneurons in the 7th layer and motoneurons in the 8th and 9th layers in L3-S3 segments subjected to 30 min of ischemia and 30 min of reperfusion were localized and their laminar distribution was specified. Spastic paraplegia fully developed 2 days postoperatively after 30 min of aortic ligation is neurohistopathologically characterized by occurrence of enlarged Nauta-positive boutons with prevailing localization in the 4th to 8th layer of the gray matter.

Spinal ascending projections to the nucleus tractus spinalis nervi trigemini of the dog.

Seven dogs were subjected 30 min to ligation of the thoracic aorta and were then kept alive 6-7 days after the ligature had been removed. Their spinal cord and brain stem were treated by the Nauta-Gygax method and the extent and appearance of preterminal and terminal degeneration of certain ascending spinal systems were analysed. In the medulla oblongata region, marked degenerating fibres from the lower thoracic and lumbosacral cord segments were found in the nucleus tractus spinalis nervi trigemini. Preterminal and terminal degenerating fibres were visualized in the caudal part of the trigeminal nuclear complex. Comparison with the literature showed these to be previously unknown projections with a relationship to the nucleus tractus spinalis nervi trigemini.