[Effects of genetic factors on genesis and growth of striated skeletal muscular tissues]. / Vplyvy genetických faktorov na genézu a rast priecne pruhovaného kostrového svalového tkaniva.

The growth is inseparable part of ontogenesis and simply is characterised as a biological process, which is outcome of internal and external changes and interaction of all organ systems. The striated skeletal muscles are developed during a prenatal period from mesoderm and individual development is finished in time of birth and also post partum. The basic sign of the last stage is a nuclei periphery movement from the centre under sarcolemma whereas myofibriles fill interior. Every individual muscular system consists of the specific particular type of muscle fibres, which were formed during embryogenesis. The nuclei of muscle fibres are postmitotic and it is evident, that only one way of muscle growth consists of coarsing and lengthening of existing muscle fibres. The muscle fibres growth and development is followed by various effects, which can be classified as genetic or other effects. By intensive studies of genetic effects was recognised that in muscles are presented not only tissular specific gene but also ubiquitous genes, which regulate processes of protein muscles and fat synthesis. The latest research exposed the existence of genes in muscles, which have influence to structural component of skeletal muscles. In present contribution we describe genetic factors effects to genesis and growth of the striated skeletal muscles.

Defensive reflexes of the respiratory system in anaesthetized rabbits during high frequency jet ventilation.

The defensive airway reflexes during high frequency jet ventilation (HFJV) were studied in anaesthetized, non-vagotomized (n = 16) and vagotomized (n = 11) rabbits. The animals were ventilated by a high frequency jet ventilator. Sneezing and coughing were evoked by mechanical stimulation of the airways. During HFJV spontaneous breathing was inhibited only in the non-vagotomized rabbits. Mechanical stimulation of the airways during HFJV evoked sneezing and coughing, in which the inspiratory component was inhibited. This inhibition occurred not only in defensive reflexes evoked from the regions with increased pressure (trachea, bronchi), but also from the nose. Vagotomy diminished but did not fully eliminate the changes in sneezing accompanying HFJV. The intensity of maximum expiratory efforts was not significantly affected by HFJV in both subgroups.

[Use of high-frequency modulated continuous positive airway pressure in experimental respiratory distress syndrome and pulmonary edema]. / Pouzitie vysokofrekvencného modulovaného CPAP pri experimentálnom RDS a edéme pl'úc.

The effect of high frequency (f = 300.min-1) modulated continuous positive airway pressure (CPAP) (0.49 kPa) was compared with that of CPAP without modulation (0.49 kPa) in 24 anesthetized rabbits in experimental respiratory distress syndrome (RDS) and pulmonary edema. RDS was induced by single excessive lavage of the lung on using the impulse and expulse effect of high frequency jet ventilation. Pulmonary edema was elicited by i.v. administration of a mixture of fatty acids. Decreased dynamic compliance of the lung and increased respiration work and rate were recorded both in experimental RDS and pulmonary edema. In RDS paO2 was reduced and paCO2 increased. In pulmonary edema, despite diminished respiration volume, ventilation was enhanced by the higher respiration rate and both paO2 and paCO2 were reduced. Application of CPAP resulted in normalization of blood gases. Modulated CPAP, compared to CPAP without modulation, further decreased paCO2 and increased paO2. The results obtained in experimental models of RDS and pulmonary edema in rabbits show the beneficial effect of high frequency modulated CPAP by pressure oscillation on values of blood gas tension.

[Does short-term high-frequency jet ventilation damage the tracheobronchial mucosa?]. / Poskodzuje krátkodobá vysokofrekvencná trysková ventilácia tracheobronchiálnu sliznicu?

In anesthetized rabbits, the occurrence of histopathological changes was studied above below and the level of the endotracheal tube opening after one-hour high-frequency jet ventilation (f = 150.min-1,Pin = 70-90 kPa, Ti = 0.5) with nonhumidified air and oxygen mixture (FiO2 = 0.6). The findings were compared with those obtained in intact rabbits and in rabbits which were inhaling nonhumidified air from the environment spontaneously via the endotracheal tube. Mechanical obstruction of the airways by mucus or necrosis of the mucous membrane was not observed. The major histopathological changes characteristic of inflammation and mechanical damage of the mucosa were recorded above the opening of the endotracheal tube. Towards the main bronchi the degree of the injury was decreasing. (Tab. 2, Fig. 2, Ref. 11.)

Spectral analysis of respiratory parameters in defensive respiratory reflexes.

A detailed analysis of respiratory signals in normal breathing and defensive respiratory reflexes was performed to obtain maximum information that can be used for modelling of respiratory processes. Physiological interpretation of the problem is difficult and requires further measurements to achieve convincing conclusions. We suggest therefore that the search for appropriate methodological backgrounds should contribute to further clarification of the problems concerned with reciprocal linkage of the respiratory signals. Appropriate attention must be paid to investigations aimed at explaining the regulatory mechanisms of breathing.

Changes in mechanics of breathing during experimental cough and sneeze in anaesthetized cats.

Pleural pressure, airflow and tidal volume during experimental cough and sneeze elicited by mechanical stimulation of the tracheobronchial and nasal mucous membranes were investigated in fifty anaesthetized cats (pentobarbital, 40 mg/kg i.p.). Pressure-volume, pressure-flow and flow-volume relations were studied during these expulsive processes. In comparison to quiet breathing there was a decrease in dynamic lung compliance in both respiratory tract reflexes (p less than 0.001), especially in their expiratory phases. As compared to quiet breathing, the total work of breathing was significantly increased (p less than 0.001) in cough (20 times) as well as in sneeze (13 times). The total lung resistance increased markedly (p less than 0.001) in both cough and sneeze compared to quiet breathing. In these expulsive processes there was also a high "cough index" (resistance calculated from the peak flow and instantaneous pressure). The flow-volume curve in cough, in contradistinction to sneeze, indicated a significantly reduced airflow of the end of expiration (at 85% of the expired volume), demonstrating a concomitant bronchoconstriction.