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Biomedical subjects

V Benes

Publications and source records attributed to V Benes.

At least 19 recordsLinked to original sources
PubMed1992

Isolation, biochemical characterization and crystallization of the p15gag proteinase of myeloblastosis associated virus expressed in E. coli.

1. The p15gag proteinase responsible for the processing of the polyprotein precursor of the myeloblastosis associated virus was obtained by a recombinant technique in an E. coli expression system. The massive expression of the intentionally truncated precursor (Pr25lac-delta gag) was accompanied by its structurally correct processing. 2. Three procedures for the purification of the recombinant proteinase from both the cytoplasmic fraction and the inclusion bodies were developed. 3. The purified proteinase was compared with the authentic proteinase isolated from MAV virions by N-terminal sequence analysis and amino acid analysis, molecular weight determination, reverse-phase HPLC and FPLC elution profiles, electrophoretic mobility and isoelectric point determination, and activity assays with proteins and synthetic substrates. The identity of both enzymes was shown. 3. Contrary to reported data, the amino acid sequence of the p15gag proteinase differs from the sequence of the homologous Rous sarcoma virus proteinase in one residue only, as follows from cDNA sequencing. 4. Crystallization of the proteinase from a citrate-phosphate buffer at pH 5.6 afforded hexagonal crystals which diffracted well as 2.3 A without deterioration.

Amino Acid Sequence↗
PubMed1991

Thalamocaudate projections in the macaque monkey (a horseradish peroxidase study).

The distribution of thalamocaudate neurons was studied in four macaque monkeys (Macaca mulatta) using the method of retrograde horseradish peroxidase (HRP Sigma VI) transport following previous aspiration of part of the frontal cortex and subcortical white matter covering the head of the caudate nucleus. After HRP injections into the head of the caudate nucleus we found retrogradely labelled neurons mainly in the intralaminar nuclei (nc. paracentralis, nc. centralis lateralis, nc. parafascicularis) and in the midline nuclei (nc. parataenialis, nc. centralis pars densocellularis, nc. centralis superior, nc. centralis intermedialis, nc. centralis inferior, nc. reuniens). Some labelled neurons were seen in the anterior thalamic nuclei (nc. anterodorsalis, nc. anteromedialis, nc. anteroventralis). In the ventral thalamus labelled neurons were seen in the nc. ventralis anterior (pars magnocellularis) and in the nc. ventralis lateralis (pars medialis). Some labelled neurons were distributed in the marginal parts of the nc. mediodorsalis. As for the caudal portion of the thalamus, labelled neurons were found in the nc. pulvinaris medialis and nc. limitans. The thalamocaudate projection is an exclusively ipsilateral projection system. The position of the thalamocaudate neurons coincides, to a certain degree, with the termination intrathalamic area of the nigrothalamic and tectothalamic projections arising from the deep layers of the superior colliculus.

Animals↗
PubMed1990

Advantages and disadvantages of the transcallosal approach to the III ventricle.

The advantages of the transcallosal approach used in children during 10 years at the Department of Pediatric Neurosurgery in Prague are: strict midline approach to the III ventricle, sparing both fornices; convenient approach to the left lateral ventricle from a right sided craniotomy. The disadvantages are: neurological sequelae, the most serious of which are mutism and disturbances of recent memory. Older children and those who showed preoperative symptoms of the disconnection syndrome exhibited more deficits after callosotomy.

Age Factors↗
PubMed1990

Our treatment philosophy of gliomas of the anterior visual pathways.

Therapeutic strategy and clinical course of 28 low grade gliomas of the anterior visual tract were analyzed and compared with results of quantitative microscopic examination. Children operated on between 1978 and 1987 were divided into four groups according to the tumor site. DNA microfluorometry and image analysis of bioptic material were used for an objective differentiation between morphologically almost identical gliomas classified as pilocytic astrocytomas (grade I). Six cases of posttraumatic gliosis were examined as controls. Results were tested with factor analysis and by multiple comparison procedures. Significant differences between quantitative parameters of tumors located along the visual pathway were found with the use of computer-aided microscopy. These results corresponded with the clinical experience and patient's outcome. A radical surgical intervention (without additional oncologic therapy) was recommended for patients with intraorbital gliomas which revealed favorable quantitative microscopic features.

Astrocytoma↗
PubMed1990

Effect of intra-arterial tissue plasminogen activator and urokinase on autologous arterial emboli in the cerebral circulation of rabbits [corrected].

We conducted a randomized, blinded controlled trial to test the efficacy of fibrinolytic therapy with tissue plasminogen activator and urokinase in the treatment of acute embolic stroke. Embolic stroke was simulated in rabbits by injecting three 0.5 x 0.5 mm fragments of autologous arterial thrombus harvested from a traumatized auricular artery. Thirty minutes after embolization the rabbits were blindly treated with tissue plasminogen activator (n = 21), urokinase (n = 20), or 0.9% saline (n = 20). At 6 hours the rabbits were sacrificed, and the cerebral vasculature was inspected for the location and number of emboli. The brain was then cut into 0.5-cm-thick coronal sections and stained with triphenyltetrazolium chloride to define areas of infarction. Treatment with either tissue plasminogen activator or urokinase significantly reduced the number of emboli present in the cerebral circulation (p less than 0.05). The area of ischemic injury was also significantly reduced (p less than 0.05) by acute fibrinolytic therapy with either tissue plasminogen activator or urokinase. However, only treatment with tissue plasminogen activator significantly reduced (p less than 0.05) the incidence of infarction. There was no evidence of intracerebral hemorrhage in any rabbit. Early fibrinolytic therapy improved outcome in this model of acute embolic stroke.

Animals↗
PubMed1990

Claustro-neocortical projections in the rhesus monkey (projections to area 6).

The distribution of claustral neurons projecting to area 6 on the convexity and medial wall of the hemisphere was studied in four macaque monkeys. In all cases, HRP-positive neurons were found almost throughout the antero-posterior extent of the claustrum in its dorsal half. Following HRP injections in area 6 on the medial wall of the hemisphere most of the labelled neurons were found in the dorsal and dorsolateral portions of the claustrum. After injections in area 6 on the hemispheral convexity, labelled neurons predominated in about the middle third of the vertical extent of the claustrum. Perikaryal polymorphism and considerable differences in perikaryal size are features characteristic of claustral neurons projecting to area 6. There is a preponderance of labelled neurons whose perikarya are noted for their multipolar or pyramidal (triangular) shape. Oval and spindle-shaped neurons were found less frequently. The size of the perikarya ranged from 11 to 26 microns while most of the labelled neurons had perikarya ranging form 14 to 18 microns in size.

Animals↗
PubMed1989

Nucleotide sequence of the right early region of Bacillus phage phi 15 and comparison with related phages: reorganization of gene 17 during evolution.

The rightmost 2016 bp of the Bacillus subtilis phage phi 15 genome were sequenced. The nucleotide sequence was compared with the homologous regions of the related phages PZA and phi 29. There are six open reading frames (ORFs) in this region of the phi 15 genome; all of them are present in the PZA and phi 29 genomes. One of the ORFs was assigned to gene 17, which is involved in the replication of the phage DNA. Gene 17 has undergone reorganization during the evolution of this phage family. Comparison of the nucleotide sequence of its mRNA-like strand in phi 15, PZA and phi 29 showed that deletions in its central and 3'-end-proximal parts are tolerated and do not interfere with the gene 17 product function. It seems that the only portion of gene 17 that has to be conserved to encode the functional product is its 5'-end-proximal part.

Amino Acid Sequence↗
PubMed1989

Impact of diffuse nitrate pollution sources on groundwater quality--some examples from Czechoslovakia.

In several regions of Czechoslovakia with intensive agricultural production, the correlation between the amount of nitrogen fertilizer applied and the nitrate content in groundwater has been recognized. Nitrate pollution of groundwater is considered to be the most serious source of nonpoint pollution in Czechoslovakia. A program of research into the effects of farming activities on groundwater quality in Czechoslovakia is under way on experimental fields (20 to 30 hectares) and, simultaneously, in regions in which shallow, vulnerable aquifers occur. The importance of the soil organic matter's stability for maintaining the groundwater quality is emphasized. Research based on nitrogen and organic carbon balance has shown that the restoration of a soil-groundwater system is a complicated process that usually requires changes in the extent and intensity of agricultural activities and consistent attention to the effects produced by natural conditions. Regional investigation of the impact of farming on shallow aquifers in the fluvial deposits of the Elbe River in Bohemia has proved the hydrochemical instability and vertical hydrochemical heterogeneity of these aquifers. The WASTEN deterministic model was used for modeling the transport and transformation of various types of inorganic fertilizers. The input data is based on laboratory and field measurements. Special topics are the verification of model calculations and the time and spatial variability of input data with respect to the unsaturated zone. The research results are being used for making regional and national agro-groundwater managerial schemes more precise, as well as for decision-making.

Agriculture↗
PubMed1989

Alternative management of carotid kinking. Surgical technique.

The simple surgical method to correct internal carotid artery kinking is presented. The artery is straightened and fixed to the surrounding tissues without arteriotomy and without interrupting the blood flow. The technique is simple and complication-free in kinks of lesser degree.

Aged↗
PubMed1989

[Experimental injuries of the spinal cord].

The authors present the results of five years' research concerned with experimental injuries of the spinal cord. The authors studied in cats and rabbits four types of problems: 1. the dynamics of injuries of the spinal cord from the morphological and biochemical aspect, in particular the development and shape of the lesion after complete severing of the spinal cord at the L2 level which was performed by 10-second extradural compression of the spinal cord with an artery forceps. 2. The possibility of resection of the destroyed spinal tissue one week after the insult and the development of autodestructive processes after this resection. 3. Resection of the entire vertebra L2 in healthy animals and shortening of the spine by means of an original stabilization apparatus. 4. Resection of the vertebra, resection of the autodestroyed parts of the spinal cord and approximation of the stumps of the spinal cord by shortening the spine. The assembled findings are discussed in conjunction with contemporary research into the reconstruction of spinal functions and possible transplantations of the CNS.

Animals↗
PubMed1988

Experimental spinal cord injury: lumbar vertebra resection to shorten the gap between spinal cord stumps.

Experimental spinal cord transection injuries followed by spinal cord destruction and gentle resection of the destructed cord tissue necessarily lead to a gap between both of the cord stumps. For any attempts to reconstruct the cord or to bridge this gap by transplantation it may be useful to narrow or close the gap. This can be done by vertebral resection. The technique of upper lumbar vertebra resection in cats and rabbits with and without spinal cord lesion is presented. The spine is shortened by approximately 20 mm by spondylectomy. This length exceeds the 10-14 mm long gap in the spinal cord which is created by a spinal cord crush injury using haemostatic forceps and the subsequent destruction zone resection which is performed seven days later. The upper lumbar vertebra is resected by the posterior approach and the spinal cord is sufficiently exposed to perform spinal cord reconstruction experiments.

Animals↗
PubMed1987

Diagnostic-therapeutic ventriculocystostomy.

Simple diagnostic-therapeutic ventriculocystostomy is described. Arachnoid, intracerebral, or intraventricular cysts are permanently connected with the ventricles by a Kifa red catheter with spirally situated holes. The pressure balance and the connection with a physiological space for resorption is maintained in this simple way. Twenty patients have been operated on over a 2-year period with good results.

Arachnoid↗