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Biomedical subjects

M Ryba

Publications and source records attributed to M Ryba.

At least 37 records · Page 2Linked to original sources
PubMed1992

HLA antigens and intracranial aneurysms.

The frequencies of the HLA-A, -B and -DR were determined in a group of 59 transplant donors who died from subarachnoid haemorrhage within three days following the rupture of intracranial aneurysm (the SAH group) and compared with those of a control group consisting of 389 donors who died from other causes. The only significant difference was in the increased frequency in the SAH group of non-typed ("empty")-DR loci in association with the DR7 phenotype. The most probable explanation of this finding is that in the SAH group the frequency of DR7 homozygotes is several times higher than in the general population, and that bearing the DR7 allele in homozygotic form is associated with a very high risk of developing potentially fatal intracranial aneurysmal haemorrhage.

Autoimmune Diseases↗
PubMed1992

The possible role of endothelium in prevention of rebleeding in experimental subarachnoid hemorrhage (SAH).

Experiments were performed on six male cats under nitrous oxide in oxygen anesthesia. Animals were paralysed and artificially ventilated. Subarachnoid hemorrhage (SAH) was produced by basilar artery puncture following clivectomy. After 10 minutes (3 cats) and 60 minutes (3 cats) the basilar artery was dissected and fixed for electronmicroscopic examination. Ultrastructural examinations revealed in the cytoplasm of the endothelial cells on the side of the vessel lumen, the presence of spherical or flattened cylindrical structures identified as Weibel-Palade bodies. In the endothelium of the proximal segment, 10 and 60 minutes after puncture, the number of these electron-dense bodies increased, and was higher than in the corresponding distal segment. The possible role of the Weibel-Palade bodies in SAH after-effects is discussed.

Animals↗
PubMed1991

Cyclosporine A prevents neurological deterioration of patients with SAH--a preliminary report.

In the present study we found that the neurological outcome in patients anaesthetized for early clipping (up to 72 h after SAH) of a ruptured aneurysm and treated with cyclosporine A was significantly better than the neurological state of control patients without immuno-suppressive treatment. The results justify the presumption that auto-immune reactions are involved in the deterioration of the postoperative neurological state of patients with SAH after rupture of an intracranial aneurysm. Supplementing a standard surgical and pharmacological treatment with cyclosporine A seems to reduce the undesirable neurological consequences of the immunologically, induced vascular disturbance after SAH.

Adult↗
PubMed1991

Immunomodulators interfere with angiopathy but not vasospasm after subarachnoid haemorrhage in rabbits.

The present study deals with the effects of immunomodulators on the morphology of intracerebral arterial walls in rabbits with experimental subarachnoid haemorrhage (SAH). Immunostimulators:thymostimuline and inosine dimethylamino-isopropanol-p-acetamido-benzoate were found to aggravate the angiopathic changes, whereas immunosuppressive drugs-cyclosporine A and azathioprine appeared to prevent the damage. The authors consider the possibility of using immunosuppressive drugs in patients with ruptured intracranial aneurysms.

Animals↗
PubMed1991

The respiratory response to magnetic stimulation of the cortex in the unanaesthetized baboon.

Transcranial magnetic stimulation has been used to study cortical input to the respiratory system in unanaesthetized baboons. Single magnetic pulse caused usually a short-latency excitation with subsequent inhibition in stimulated inspiratory phase and change in the amplitude and timing of the respiratory cycle. The results suggest that cortical information is processed by the medullary pattern generator.

Animals↗
PubMed1990

An electron immunocytochemical study of the basilar artery in rabbits after subarachnoid haemorrhage (SAH): a preliminary report.

Vascular endothelial cells of the basilar artery and secretory axons of the neurohypophysis from rabbits after experimental subarachnoid haemorrhage were investigated by postembedding peroxidase--anti-peroxidase technique for electron microscopy to detection of vasopressin (VP). The results indicate an lack of VP-positive endothelial cells in basilar artery, while VP-positive secretory granules were commonly present in the neurohypophysis. The results are discussed in terms of pathophysiological aspect of subarachnoid haemorrhage.

Animals↗
PubMed1989

Immunological method for prediction of progress in neurological deficit in patients with intracranial aneurysm rupture.

Skin tests of nonspecific antigens (immunoskin test Sevac) were performed on patients suffering from intracranial aneurysms, scheduled for surgical clipping. It was found that high antibody titre correlated well with the severity and progress of neurological deficit developing after surgery. This deficit was absent in patients who exhibited low antibody titre in response to the skin test before surgery. These results indicate that the immunological processes may play a role in the development of neurological deficit after neurosurgical procedures. Thus the skin test employed may have prognostic value in predicting neurological deficit following intracranial aneurysm surgery.

Adult↗
PubMed1989

[Nasal obstruction in patients with sleep apnea].

The authors described the clinical signs and consequences of suffocations during sleep apnea. They presented the results of the surgical intervention of nasal obstruction in patients with sleep apnea. The during-all-night examinations of these patients proved the possibility of positive effects of surgical intervention of nasal obstruction in patients with sleep apnea.

Adult↗
PubMed1987

Cooling of ventral medullary intermediate areas and respiration in the cat.

We sought to address the contribution of the ventral medullary intermediate (I) areas to respiratory regulation in the close loop condition. The experiments were done on anesthetized, spontaneously breathing cats. The transient and steady-state neural respiratory output responses to longlasting cooling of the I areas and to vagotomy and hyperoxia performed during the cooling period were investigated. Cooling of the I areas resulted in an initial transient inhibitory response followed by respiratory output increase in the steady-state, provided other respiratory inputs were maintained intact. This investigation calls into question the crucial role of the I areas in regulation of respiration in the close loop condition.

Animals↗
PubMed1985

Brain metabolism in deep controlled hypotension in neurosurgical patients.

Changes in the lactate and pyruvate levels and lactic dehydrogenase activity in the cerebrospinal fluid were followed in 56 patients anaesthetised for neurosurgery. Mean arterial blood pressure (MAP) was reduced in these patients from about 90 to about 35 mm Hg. This allowed to safely place a clip at a brain artery aneurysm. In spite of deep hypotension, ischaemia described by other authors in such cases was never observed. Changes in lactate and pyruvate concentrations, lactate/pyruvate ratio and lactic dehydrogenase activity justify the conclusion that we were dealing with an undisturbed metabolism of the brain tissue. The levels of metabolic parameters, even when increased in hypotension, fell well within the range of physiological values. Attention is called to the fact that partial oxygen pressure in arterial blood during controlled hypotension was about 100 mm Hg, a value considered as limiting to oxygen metabolic transformation within the central nervous system in deep hypotension. We also suggest a different mechanism of passage of lactates and pyruvates through the blood-brain barrier.

Adult↗
PubMed1985

Influence of vagal input on cerebral blood flow in monkeys and dogs after experimental cerebral vasospasm.

Cerebral blood flow (CBF) was a response to experimental subarachnoid haemorrhage (SAH) in four monkeys ,and three dogs. Decrease in CBF was observed in the white and gray matter and in the flow measured within the internal carotid artery as the result of SAH. Bilateral vagotomy enhanced CBF in the gray matter and blood flow in the internal carotid artery to values exceeding the control ones. Results suggest the existence of a receptor susceptible to subarachnoid haemorrhage and connected with vagal nuclei.

Animals↗
PubMed1984

Kinetics of transport and metabolism of 1-beta-D-arabinofuranosylcytosine and structural analogs by everted perfused rat jejunum.

Few reports have dealt with the kinetics and metabolism of AraC and analogs by rat intestine. Using everted rat jejunum with continuous perfusion, it was possible to demonstrate that AraC and Cyd cross the intestinal barrier(s) by a carrier mediated process which was saturable and exhibited fairly good fitting of the flux rate by Michaelis-Menten equation. The transport rate of different analogs was not consistent with the pH-partition theory of membrane transport of drugs being rather dependent on the chemical structure of the nucleoside. A free amino group of cytosine increased the rate of transport within the present series of AraC analogs. There was a detectable deaminase as well as esterase activity towards AraC and its analogs in rat jejunum.

Animals↗
PubMed1984

Structure-intestinal transport and structure-metabolism correlations of some potential cancerostatic pyrimidine nucleosides in isolated rat jejunum.

Both transport and biotransformation processes for a series of pyrimidine nucleobases, ribonucleosides, 2'-deoxyribonucleosides, and acetyl and 5'-substituted derivatives of the cancerostatic agent araC were studied in the isolated everted rat jejunum with a continuous perfusion technique. Metabolic alterations during penetration were assessed by HPLC. 5'-Halogeno and 5'-deoxy derivatives of cytosine nucleosides exhibited higher transport rates and higher stability towards the deamination reaction than did unsubstituted derivatives. Octanol-buffer partition coefficients were estimated for the study compounds, and fragmental constants for the sugar moieties of nucleosides were assessed. With the present study compounds there was no correlation between lipophilicity and transport rate, as previously reported, but there was a correlation between lipophilicity and metabolic alteration of araC derivatives (r = 0.99, n = 5).

Animals↗