Biomedical subjects
Publications and source records attributed to V Novák.
Techniques for modeling of a stochastic activity of neurons are briefly reviewed. Our model is proposed, some experimental results with input Gaussian stochastic processes are discussed, and the concept of e-curves is introduced.
Techniques for modeling of a stochastic activity of neurons are briefly reviewed. Our model is proposed, some experimental results with input Gaussian stochastic processes are discussed, and the concept of e-curves is introduced.
Based on their longstanding experience of a department with surgical treatment of small-cell carcinoma of the lungs, the authors give an account of their experience. During the five-year period (1988-1992), when also patients in the third stage of the disease were operated, the authors followed up the survival after operation in relation to the presence or absence of N2. During the above period 31 patients were operated on account of small-cell carcinoma. This number comprised 9 patients in stage I and II, 14 patients in stage III, and in 8 patients on account of the advanced stage of the disease explorative thoracotomy was performed. Although the patient groups during the mentioned period were not large, the results are comparable with those of other, larger investigations. Patients operated in stages without tumourous affection of the mediastinal lymph nodes survived resection of the lungs supplemented by adjuvant chemotherapy significantly longer than patients with N2 affections and a similar therapeutic procedure. Based on the achieved results the authors do not recommend resection of the lungs in the IIIrd stage of the disease as the primary or as an adjuvant therapeutic modality.
In the last years drainage shunts for otherwise untreatable glaucoma are effective. An own device is described, manufactured from medical, grade silicone. It consists of a tube with inner diameter of 0.4 mm and outer diameter of 0.9 mm. This tube is inserted in a disc, resembling a contact lens with a diameter of 12 mm, radius of 12 mm and a thickness of 0.55 mm. This part is fixed under a conjunctival flap between two recti muscles and the tube after proper shortening is introduced into the anterior chamber. The operation technique, results and complications in the first 11 eyes of 11 patients are reported. In 2 eyes it was not possible to lower the tension, in one only with additive medication. 2 eyes had a permanent hypotony. In 6 eyes a long term pressure normalisation was seen.
The contamination of the environment requires the content of heavy metals in medicinal plants to be limited and controlled. The present paper aims to demonstrate the possibilities of application and advantages of a modern polarographic method, differential pulse chromatography (DPP), in the identification and determination of heavy metals in the plant material. In the plant drugs Flos chamomillae and Flos calendulae, the heavy metals Pb, Cd, Ni, Zn, Cu and Fe were identified and determined. The World Health Organization (WHO) indicated Pb, Cd and Ni as dangerous toxic trace elements.
During the development of a Czechoslovak silicone cannula with an external diameter of 0.9 +/- 0.1 mm for reconstructive surgery of the lacrimal pathways a modification was elaborated to ensure adequately the inner cannulation of lacrimal canals, discontinuous due to injury. The surgical method involves the insertion of the cannula designed by the authors by means of fixed silk for sutures by means of a fixed loop at the ends of the cannula. Using a pigtail probe, first the stitch is drawn through the lacrimal pathways and then the fixed cannula.
The authors designed and made a prosthesis for total replacement of the middle ear ossicular chain (TORP) from Silastic MDX 44-516. A great advantage of this substitute is that it can easily be modified to a prosthesis for partial replacement of the middle-ear ossicular chain (PORP). The transfer properties of the PORP type prosthesis were verified by using an electroacoustic model measurement. Very good anatomical and functional results were obtained in the clinical testing of both types of middle-ear substitutes. No undesired reactions to the implanted polymer were observed.
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The authors describe a hybrid computer neurone model intended for the investigation of stochastic transformations effected by neurones in correlation to some of their physiological parameters. The model is designed so as to give the best possible characterization of the internal dynamics of a neurone with minimum limiting conditions. It allows the generation of suitable input stochastic processes or operates with input processes obtained experimentally in the living neurone and it carries out basic statistical tests of the output stochastic process.
The authors describe the effects of changes in excitatory and inhibitory synapse weight on the number of spikes generated in the presence of constant absolute refractory phase and threshold level values. Input stochastic processes with Gaussian distributions were presumed. The problem was resolved in a hybrid computer model of stochastic neuronal activity. The results are given in the form of "e-curves", "i-curves" and gradient fields. It was shown that, in a set of paired values of the two weights, zones could be found in which the number of generated spikes depended mainly on just one of them. It was also shown that, in a given neurone with a fixed synapse morphology, the effect of the individual synapses on the number of generated spikes altered with changes in input stochastic processes to the synapses.
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Using fluorescein-labelled antibodies against gamma, mu and alpha chains, Ig-containing cells in palatine tonsils were studied in 120 patients. The aim of this study was to determine the most frequently repeated typical findings as regards the numbers and localisation of these cells in tonsils and to confront the data obtained with the concept that tonsils are a component of the local immunity system. The preponderance of IgG over IgA cells was confirmed, both cell types being preferentially localized in extrafollicular tissue whereas IgM was mostly found in germinal centres. Together with progressing tonsillar atrophia, the frequency of positive findings of IgM decreased, whereas the numbers of IgG and IgA cells were proportional to the amount of remaining lymphoid tissue. IgA cells were not preponderant in tonsils and their localization in the surface layer of epithelium was rather exceptional, SC antigen could not be demonstrated unequivocally and the morphological picture in germinal centres was characteristic for IgM production rather for IgA. Thus the palatine tonsils according to the content and distribution of immunocytes, correspond to the lymph node rather than to an organ involved significantly in the local antibody formation.
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