PubMed Health⌕ Search

Biomedical subjects

J Vávra

Publications and source records attributed to J Vávra.

At least 19 recordsLinked to original sources
PubMed1999

The severe combined immunodeficient mouse as a definitive host for Sarcocystis muris.

Peroral and intraperitoneal inoculation of severe combined immunodeficient (SCID) mice with cystozoites of three coccidia of the genus Sarcocystis (Protozoa, Apicomplexa; S. dispersa, Sarcocystis sp., and S. muris) revealed that after peroral administration, only S. muris could develop in the immunodeficient mouse host. The cystozoites of S. muris transformed into gamonts and, after fertilization, performed sporulation with the production of infectious sporocysts in the small intestine of the SCID mice. Impaired immunity is probably responsible for the unusual behavior of S. muris (which is normally the heteroxenous mouse-cat parasite) in the SCID mice. We hypothesize that the phylogenetic distance between the intermediate and final hosts is the reason why cystozoites of the two other Sarcocystis species tested (S. dispersa with a mouse-owl cycle and Sarcocystis sp. with a murine rodent-snake cycle) could not develop when inoculated into SCID mice.

Animals↗
PubMed1998

Some ultrastructural data on Microsporidium ceylonensis, a cause of corneal microsporidiosis.

Sections of corneal tissue infected with Microsporidium ceylonensis were restained or processed for electron microscopy. Confirmation was obtained that the parasite develops in macrophages and that spores are uninucleate. New information is provided that sporoblasts and spores develop synchronously within a membrane in the host cell, spores have an anisofilar polar tube of 6-10 wide coils and 2-3 narrow coils and details are given of the spore wall and internal organisation. The parasite was compared on the one hand with Encephalitozoon, which exhibits asynchronous intravacuolar development of merogonic and sporogonic stages and has spores with isofilar polar tubes and on the other hand with species reported from mammals, of which the sporogonic stages develop synchronously within sporophorous vesicles and the spores have anisofilar polar tubes. Even so, a generic emplacement could not be established. Attention is drawn to the similarities between M. ceylonensis and Nosema sp. described from the cornea of a woman in Botswana.

Animals↗
PubMed1993

Staining of microsporidian spores by optical brighteners with remarks on the use of brighteners for the diagnosis of AIDS associated human microsporidioses.

Conditions for the effective fluorescence labelling of microsporidian spores by optical brighteners, based on the presence of chitin in the spore wall, are described. Spores of Vairimorpha ephestiae, V. necatrix, V. plodiae, Nosema bombycis, N. apis, N. algerae, Encephalitozoon cuniculi and Enterocytozoon bieneusi were examined. The degree of binding of Calcofluor White M2R (CFW) to untreated spores depends on the conditions and time of storage and the degree of bacterial contamination of the spore sample. Unpurified spores, stored in water are unreliable as control material for the estimation of CFW labelling. However, spores subjected to alkaline treatment by NaOH before CFW application are visualized with ease under all experimental conditions by their bright, not quenching fluorescence in shortwave light (approximately 350 nm) in CFW dilutions of 10(-4) or even lower. Similar improvement in labelling is achieved by exposing spores to CFW dissolved in 0.5-1N NaOH. As well as Calcofluor White M2R other optical brighteners (e.g. Uvitex 2B, Ciba-Geigy or Rylux BA, Ostacolor) can be used for labelling of spores.

AIDS-Related Opportunistic Infections↗
PubMed1992

Breathlessness in healthy subjects at physical load.

The aim of the study was to ascertain the reasons which lead to discontinuance of exercise on the bicycle ergometer in healthy untrained subjects and to assess the dependence of dyspnea on breathing pattern and on ventilation. The physical load was progressively increased to the maximum in 11 volunteers at the age of 21 +/- 1 years. During exercise some cardiovascular and respiratory parameters were measured simultaneously with the degree of dyspnea. Breathlessness was rated by means of a scaling according Borg, where 0 indicates no, 10 maximal dyspnea. Dyspnea was not a reason for termination of maximal exercise, its value being 6 +/- 1.9 in men and 4.5 +/- 2.3 in women at the end of exercise. The reasons for termination of exercise were the sensations of general fatigue and pain in lower the extremities. The degree of dyspnea correlated with the minute ventilation, with the decrease of end-tidal CO2 concentration, with the duration of exercise and some other values. The grading varied among subjects. The mathematical dependence of dyspnea was summarised by two regression equations, one without suppression, the other with suppression of interindividual differences in responses.

Adult↗
PubMed1990

The relationship between changing body height and growth related changes in maximal aerobic power.

In order to analyse the relationship between maximal aerobic power (VO2max) and height, body mass and lean body mass a multi-longitudinal survey was conducted on three different age groups of randomly selected children from a small Czech community. Beginning at the initial ages of 8, 12 and 16 years subjects were subsequently retested three times at 2-year intervals. At overlapping ages there were no differences in the various age groups between height and VO2max. By utilizing mean values for the various parameters at specific calendar ages a growth curve was constructed for each sex for the age range 8-20 years. The values were compared with longitudinal studies in various countries and no substantial differences were found. When VO2max was then compared to height, body mass and lean body mass it was apparent that the almost linear relationship with height was the most precise. In addition the children remained, generally speaking, in their same rank order for VO2max for the three different age groupings.

Adolescent↗
PubMed1990

Ventilation of an additional dead space.

The authors studied the question of the completeness of ventilation of an additional dead space in the form of a tube 3 cm in diameter and with a volume of 600 ml. Seven young volunteers were examined while breathing with and without the tube, seated at rest and during a two-grade exercise load on a bicycle ergometer. The criterion of ventilation of the tube was enlargement of the dead space by 600 ml during breathing through the tube. The functional dead space was always calculated from the tidal volume and the CO2 concentration in mixed expired air and in an end-tidal sample, using the Bohr equation. In every case, the tube was found to be completely ventilated by breathing, both under resting conditions and during exercise. In breathing during the bicycle exercise, the ratio of the functional dead space to tidal volume fell from 0.3 to 0.19 and a similar decrease was recorded in breathing through the tube.

Adolescent↗
PubMed1990

[Comparison of the physical fitness of the young population of Czechoslovakia with similar data from other European countries].

In order to analyze the relationship between VO2 max and height, body mass and lean body mass a multi-longitudinal survey was conducted on three different age groups of randomly selected children from a small Czech community. Beginning at the initial ages of 8, 12 and 16 years subjects were subsequently retested three times at two year intervals. At overlapping ages there were no differences in the various age groups between height and VO2 max. By utilizing mean values for the various parameters at specific calendar ages a growth curve was constructed for each sex for the age range 8 to 20 years. The values were compared with longitudinal studies of various countries and no substantial differences were found. When VO2 max was then compared to height, body mass and lean body mass it was apparent that the almost linear relationship with height was the most precise. In addition the children remained, generally speaking, in their same rank order for VO2 max for the three different age groupings.

Adolescent↗
PubMed1989

The pattern of breathing and the ventilatory response to breathing through a tube and to physical exercise in sport divers.

Well-trained divers can be expected to differ from healthy controls in their ventilatory response to breathing through a tube and to physical exercise. Therefore, we measured their minute ventilation (VE) at rest and during breathing through a tube combined with two levels of physical exercise (1 or 2 W.kg body weight-1). For breathing through a tube an additional dead space of 600 ml was used. All divers were trained in the breath-hold technique and in the use of the breathing apparatus. Their mean period of training as divers was 9 +/- 6 years. The approximate age of the subjects was 25 years. The pattern of breathing and the oxygen uptake were measured by spirometer, the end-tidal concentration of CO2 was measured and all experiments were carried out above sea level. The ventilation of the divers at rest was comparable to that of the controls. During physical exercise it was smaller whether during breathing through a tube or not. The inadequate increase of VE during exercise in divers was associated with hypercapnia only at a higher physical work intensity (of 2 W.kg-1). This finding is interpreted as a lower chemoregulatory response to the combined stimuli of hypercapnia, hypoxia and physical exercise. In some situations significant bradypnoea and higher tidal volumes were found in the divers.

Adolescent↗
PubMed1989

[Surgical lengthening of the femur using the Poldi 7 device].

The work presents the evaluation of longterm results of the surgical prolongation of the femur. The examined group includes 10 patients: 5 boys and 5 girls which the authors treated in the years 1978-1986. Their average age in time of operation was 15.5 years. The youngest was 8 and the oldest 25 years old. Shortening was in 4 cases caused by poor healing of the fracture, in three cases it was a results of congenital hypoplasia of the femur or the whole lower extremity, in three cases it was caused by osteomyelitis. The duration of the prolongation was on average 4 months, the external fixation device was removed on average after 8 months. The mean prolongation was 8 cm, ranging from 4 cm to 11 cm. In 8 cases healing was without complications, twice there occurred a fatigue fracture which was treated by plate osteosynthesis.

Adolescent↗