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Biomedical subjects

L Novák

Publications and source records attributed to L Novák.

At least 37 records · Page 2Linked to original sources
PubMed1991

Plasma xanthine oxidase and resistance to hypoxia: effect of purines and alcohol administration.

The administration of allopurinol significantly increased resistance to repeated hypobaric hypoxia, while hypoxanthine decreased it. The administration of adenine or inosine (25 mg/kg) was without effect. The results show pathogenic significance of xanthine oxidase-dependent production of free oxygen radicals in posthypoxic damage. In other experiments, the administration of 50% ethanol (12 ml/kg) by gastric catheter increased plasma xanthine oxidase activity in both rats and hamsters.

Adenine↗
PubMed1991

[The use of CO2 laser in bone surgery].

Authors examined during the trial of a CO2 laser of type TUNGSRAM TLS-61 the possibility of its use in the orthopaedic surgery. The output necessary to cut the skin and bony tissue, the speed of cutting and the extension of tissue necrosis were determined in experiments in vitro and in vivo. According to their observation the fusion of the bone cut with CO2 laser takes the same time as after the traditional osteotomy, however in the first three weeks the callus formation falls behind. The possibility of a curved cutting and of the coagulation haemostasis may ensure a fine prospect to this method.

Animals↗
PubMed1991

[Influence of calcium hydroxide under filling cements].

In the paper lying before the authors estimate changes of pH-values of the Calcium hydroxide (Calxyd) after contact with a zinc oxide phosphate cement (Adhesor), a polyacrylate cement (Adhesor-Carboxy) and a zinc oxide eugenol cement (Caryosan). The last shoved to be best qualified for over capping of pasty preparation with calcium hydroxide.

Analysis of Variance↗
PubMed1991

[Biocompatibility of a chromium-cobalt alloy studied in vitro].

The authors followed the effect of chromcobalt alloy on human cells cultured in vitro. They found out that corrosion increases the cytotoxicity of this alloy, meanwhile the perfectly laboratory elaboration, especially polishing of substitution decreases the cytotoxicity. We recommend for the complex cytotoxicity review, to test the metals and alloys also after laboratory elaboration, it means in the condition it is passed on to the patient.

Biocompatible Materials↗
PubMed1991

[Reaction of HeLa cells to the presence of Evicrol varnish studied by electron microscopy].

The electron-microscopical changes of cells produced by underlying Evicrol varnish are described. The latter is used in preventive stomatology to underlay fillers, those from composite materials, especially. It is designed to prevent the pulp damage through these materials. The changes of in vitro cultivated cells have in contrast been confirmed with previous experimentation showing that the varnish itself causes toxicity for living cells and therefore is not convenient to undercoat cavities in the proximity of pulps.

Dental Materials↗
PubMed1991

[The effect of Aspan on live cells in vitro].

Cytotoxicity of an experimental vitrioionomeric cement Aspan has been proved on the basis of morphological reaction of cells cultivated in vitro. There was no decrease in toxic action of Aspan when recovered with Silfolit and Evicrol varnishes.

Dental Cements↗
PubMed1990

[Treatment of defects of the cervical portion by a "sandwich" filling].

The authors draw attention to some peculiarities of treatment of class V cavities by aesthetic fillings. Combined filling made from silicocarboxyl cement and composite filling material prove useful. In teeth with preserved pulp sandwich fillings are used which contain three layers (base, intermediate retention layer of silicocarboxyl cement and composite material). In pulpless teeth, the base is not needed and the term combined filling (two layers) is more appropriate.

Composite Resins↗
PubMed1990

[Investigations of cytotoxicity of Heliosit depending on its polymerizing in vitro].

In this paper the authors describe the changing in cell culture of epithelioid cells of a permanent HEp-2-line basing on the one component composite Heliosit. Following the experiences with farmer test the authors mean that contact and local toxicity are not so heavy but depending from the polymerization of the materials. Warning is the arretation of some phases in cell cyclus and the changing of epithelioid cells in fibroblastoid cells. May it is a cell transformation necessary to examine in special tests.

Cell Transformation, Neoplastic↗
PubMed1990

Influence of hypoxanthine, allopurinol and adenine on resistance of rats and hamsters to hypobaric hypoxia.

The survival time of rats and hamsters in lethal hypoxia was measured after a sublethal exposure and a normoxia break, at the beginning of which purines were administered intraperitoneally in the following dosages: 25 mg/kg hypoxanthine, 50 mg/kg allopurinol, 25 mg/kg adenine. In rats, administration of hypoxanthine decreased the survival time by 20%, administration of allopurinol increased it by 25%. Oxygen overpressure of 5 kPa between the two hypoxic doses resulted in larger differences after hypoxanthine and allopurinol application as compared to normoxia break. In hamsters, the effect of allopurinol, hypoxanthine and oxygen was similar, but smaller than that in rats. Adenine did not significantly affect the survival time of rats or hamsters. If hypoxia was applied only once, the purines had no effect on the survival time of rats or hamsters. No measurable XOD activity was observed in hamsters, whereas in adult rats, 99.46 +/- 13.85 nkat/l were found.

Adenine↗
PubMed1989

[Reaction of cells cultured in vitro on 2 self-polymerizing adhesives].

Cytopathological changes due to self-polymerizing enamel adhesives Evikrol Bond and Concise Enamel Bond were studied. Both the materials were toxic for in vitro cells. They caused death of the cells and degenerative changes appeared in some organelles including the cell membrane. This resulted in bad adhesion of the cells to the substrate. Extractions of these adhesives caused also changes in the karyoplasm. The observed change of epithelioid HEp-2 permanent line cells into fibroblastoid cells requires, however, further verification by means of special tests.

Acrylic Resins↗
PubMed1989

[Cytotolerance of bioceramics in cell culture studies].

Biological effects of ceramic implant material of Czechoslovak make prepared on the basis of alumina were studied here. The material was proved to be quite inert both toward epithelioid Hep-2 cells and toward L-line fibroblastoid cells in experiments with nonspecific application, i.e., in cell cultures.

Aluminum↗
PubMed1989

Hypoxanthine in diagnosis, prognosis and pathogeny of hypoxic injury.

Oxypurines (hypoxanthine + xanthine, HX) were measured polarographically in the mixed umbilical cord blood plasma, the maternal venous blood plasma and in the anterior amniotic fluid of 104 deliveries. The HX increase was found in groups with clinical signs of perinatal hypoxia. The HX concentration in the mixed umbilical plasma above 15 umol/l (i.e., means +/- 2 S.D.) should be considered as pathological. The following results of experiments on animals suggested a possible pathogenic significance of xanthine oxidase (XOD) reaction on hypoxic injury: The higher the plasma XOD activity of different species (guinea pig, hamster, rat, mouse) the shorter was the survival time of the species in the interrupted hypoxia. Administration of hypoxanthine decreased the survival time of rats in the interrupted hypoxia, while the administration of allopurinol increased it. Allopurinol suppressed the post-hypoxic autoimmune response of the rats to brain tissue.

Amniotic Fluid↗
PubMed1988

Plasma xanthine oxidase activity correlates with the resistance to severe hypoxia in different species.

A rapid polarographic method of measuring the O-form of xanthine oxidase (XOD) is described. Activities of this enzyme and oxypurine concentrations were measured in the plasma and cerebrospinal fluid (CSF) of 1, 12, 25 and 60-day-old rats. In the CSF, the highest oxypurine concentration was found in the group of 12-day-old rats (34.07 +/- 12.37 mumol.l-1), and it remained nearly at the same level in groups of older animals. Oxypurines in the plasma, on the contrary, are polarographically measurable on the first day of life; in groups of older rats their concentration is below the sensitivity of the method (5 mumol.l-1). This was explained by the development of XOD activity in the plasma, which increased from 8.17 +/- 2.80 to 99.46 +/- 13.85 nkat.l-1 during the first 60 days of postnatal life. The higher the normal plasma XOD activity, the shorter was the survival time of the species during interrupted hypobaric hypoxia. Adult guinea-pigs and hamsters have no measurable XOD activity in the plasma; adult rats and mice have 99.46 +/- 13.85 and 259.69 +/- 58.23 nkat.l-1, respectively. The survival time of these animals at 10,500 m was measured following exposure to an altitude of 8,000 m for 30 min and 15 minute normoxia. Guinea-pigs survived 100.8 +/- 13.84 min, hamsters 54.25 +/- 11.33, rats 25.2 +/- 5.37 and mice 3.33 +/- 1.00 min.

Animals↗