Features and mechanisms of realization the respiratory influences of the extrapyramydal system structures

In the publication the modern condition of the problem of suprabulbar regulation of breathing is analysed. The review on structure, neurochemistry and anatomic connections of the red nucleus and substantia nigra with the medullary respiratory center is submitted. The data on the respiratory effects of GABA and apomorphine microinjected into the red nucleus and substantia nigra as well as effects of their electrostimulation after the blockade of GABA and dopamine receptors in the respiratory center are discussed. The conceptual scheme of the mechanisms of realization the respiratory influences of the extrapyramydal system is offered.     

Effects of ethanol and acetaldehyde on iron-sulfure centers in the mitochondrial respiratory chain.

Incubation of submitochondrial particles with relatively low concentrations of ethanol (20–100 mm) or acetaldehyde (1–10 mm) produces alterations in the electron paramagnetic resonance spectra of the iron-sulfur centers in the NADH dehydrogenase segments of the respiratory chain. The iron-sulfur centers in the NADH dehydrogenase region are most sensitive to both ethanol and acetaldehyde, in comparison to the iron-sulfur centers in succinate dehydrogenase and the cytochrome b-c region. Centers N-3, 4, N-5, 6 and N-1b are affected after relatively short incubation periods (3–30 min) while center N-2 shows considerable sensitivity over somewhat longer incubations (20–90 min). The most ethanol-sensitive center in the succinate dehydrogenase region of the respiratory chain is high potential iron-sulfur protein-type center S-3. Potentiometric analysis shows that these alterations are not due to simple changes in the redox state caused by addition of dissolved oxygen. Changes in the electron paramagnetic resonance spectra can be correlated with decreased rates of oxidation of NADH and, to a lesser extent, succinate in both ethanol- and acetaldehyde-treated submitochondrial particles.     

Serotonin receptors: guardians of stable breathing

Disturbances of breathing arising from failures of the respiratory center are not uncommon. Among them, breath holding and apnea occur most frequently as consequences of pulmonary and cardiac diseases, hypoxia, head trauma, cerebral inflammatory processes, genetic defects, degenerative brain diseases, alcoholism, deep anesthesia and drug overdose. They are often life-threatening and fail to respond to existing pharmacotherapies. After extensive research, there is now a reliable basis for new strategies to treat respiratory disturbances by pharmacological manipulation of intracellular signaling pathways, particularly those involving the serotonin receptor family. Specific activation of these pathways effectively prevails respiratory disturbances and can be extended to treatment of life-threatening respiratory disorders in patients.     

Central mechanisms of respiratory rhythmogenesis

The organization and role of a respiratory neuronal generator as a part of the medullary respiratory center, including the role of afferent systems in the mechanisms of initiation and regulation of the center cyclic activity, are considered. Intrinsic organization of the respiratory generator and specific features of its functioning are analyzed, and the two main hypotheses concerning the mechanisms of rhythmic respiratory activity generation are discussed.Neirofiziologiya/Neurophysiology, Vol. 26, No. 3, pp. 230–236, May–June, 1994.     

Structural and functional organization of the respiratory center

The main experimental data on the organization of the respiratory center accumulated during the past 200 years are summarized. It is emphasized that the existence of separate, reciprocally interrelated, inspiratory and expiratory centers has never been proved. The notion of multiple respiratory centers in the CNS, including pneumotaxic, apneustic, gasping, and deep-exhalation centers, which allegedly underlie the multiple forms of respiratory movements, is demonstrated to be unjustified. Upon systemic consideration, the evidence in favor of the decisive role of neurons of the pre-Bötzinger complex and preinspiratory neurons in initiating the respiratory rhythm and maintaining rhythm generation in the respiratory center is contradictory and unconvincing. It is assumed that the respiratory center located in the medullary region of the brain of intact animals and humans fulfills the main functions of endogenous self-sustained generation of the respiratory rhythm, chemoregulation, and mechanoregulation in the respiratory system in an integrated manner, according to the general requirements of the body at a given moment.     

Respiratory system activity in laser irradiation of brain structures

It has been shown that the low-level laser radiation with the wave-length in the red part of spectrum changes greatly the activity of the respiratory center under the direct influence on the rats' brain structure. The influence of light may have activating or inhibitory character; sometimes symmetry in the respiratory center activity is disturbed. The difference of the effects under the radiation of the sensomotor area of the cerebral cortex hemispheres and the area of the bulbar respiratory center has been found out. It is supposed that one of the reasons of the functional state of the respiratory center variations is the metabolism change in its structures.     

respiratory responses to microinjections of bombesin into the solitary tract nucleus, and the mechanism of their realization

We investigated the respiratory effects of 10-(13)-10(-4) M bombesin microinjected into the solitary tract nucleus of adult anaesthetized rats. Bombesin markedly increased ventilation, tidal volume and electric activity of inspiratory muscles. The respiratory response was most pronounced when bombesin administered in mean concentrations (10(-10)-10(-7) M). We found that the respiratory effects ofbombesin could be based on its capacity for inhibition of Hering-Breuer inspiratory termination reflex at the level of the solitary tract nucleus. These results in aggregate with pattern of the distribution of endogenous bombesin and its receptors in the solitary tract nucleus area suggest the involvement of bombesin in the respiratory control via dorsal structures of the respiratory center.     

Significance of the corpus callosum in the paired activity of the respiratory center

The asymmetrical reactions of respiratory neurons of the right and left halves of the respiratory center and varied changes in bioelectrical activity of external intercostal muscles on both sides of the chest were discovered in experiments on anesthetized cats in response to successive electrical stimulation of the symmetrical cortical areas of the right and left cerebral hemispheres before and after callosotomy. It was demonstrated that callosotomy increased on both sides of the respiratory center the quantity of neurons responsive to ipsilateral cortical stimulation and determined the character of the asymmetrical reactions of right and left respiratory neurons and intercostal muscles. On the basis of the data obtained it is concluded that the corpus callosum contributes to the functional integration of both halves of the respiratory center.     

Determination of concentrations of elements in the atmospheric aerosol of the urban and rural areas of beijing in winter

The proton-induced X-ray emission technique is one of the most suitable methods in the study of the multielement content of atmospheric aerosols. Atmospheric aerosol samples were collected in winter using an eight-stage cascade impactor at a site of the urban center and a rural site of Beijing. The aerosol samples collected were analyzed to determine maximum, minimum, and average concentrations of up to 20 elements and the ratios of the average element concentrations for the coarse to fine particles (C/F) by the PIXE technique. It has been found that the average elemental concentrations in the urban center are higher than those in the rural area, except S and Br. The concentrations for S and Pb in the atmospheric aerosols are found to be less than the results of previous measurement, but their concentrations in the fine particles increased in winter in the samples from the urban center. The deposition probability of the International Commission on Radiological Protection (ICRP) mode and the mass particle-size distributions of the elements determined in the urban center have been utilized to evaluate inhalable particulate matter fractions retained in the three regions of one’s respiratory tract and their harm to human health is discussed.     

Effect of a polarizing current on unit activity in the respiratory center

Single unit activity in the respiratory center in the medulla was recorded in rabbits anesthetized with urethane. The neurons were polarized through the extracellular recording microelectrode by currents of different strength and polarity. In most cases a current in the positive direction (+ to the electrode tip) increased, while a negative current decreased, the firing rate. Most indices of the firing pattern of the respiratory neurons were changed by the action of the polarizing current. The coefficient of phase shift between the pneumogram and unit activity, determined by calculating the cross-correlation function between these two processes, was the most stable index. Since it takes into account the temporal and frequency characteristics of volley activity of the respiratory neurons, this coefficient can serve as a basis for their classification. The dynamics of respiratory neuronal function under subthreshold conditions was revealed by the polarization method. It was shown, in particular, that the shape of the variable component of respiratory unit activity is close to sinusoidal and differs from that suggested by the hypothesis of reciprocal interaction between two groups of neurons.Rostov State University, Rostov-on-Don. Translated from Neirofiziologiya, Vol. 4, No. 3, pp. 280–285, May–June, 1972.     

Preventive measure of massive spreading of influenza and acute respiratory viral infections

Influenza and acute respiratory viral infections (ARVI) continue to be one of the most actual medical and social-economic problem. But problem of high incidence of ARVI often regarded as problem of influenza only. Information about methods of prognosis of massive spreading of ARVI complex and universal system of their prophylaxis including influenza is presented in the article.     

Exogenic proteins in the human exhaled breath condensate

The analysis of the protein composition of exhaled breath to diagnose diseases of the respiratory system raises a problem of differentiation proteins of expressed in the tissues of the lungs and respiratory tract (endogenous) and got in the respiratory system from the ambient air in the process of respiration (exogenous). In this work an attempt was made to estimate a set of exhaled exogenic proteins by mass spectrometry coupled with nanoflow HPLC. Six-month isolation of healthy donors indoors with air cleaned of dust leads to removal from the spectrum of exhaled proteins of some keratins that are considered therefore to be exogenic. Non-keratin proteins may also circulate between the ambient air and human respiratory ways, but their concentration appears to be significantly lower the keratin concentrations (especially epidermis keratin). Among non-keratins dermcidin seems to be the most significant exogenic protein of exhaled air. The conclusion of the diagnostic value of exhaled proteins can be done only after careful comparison of the results of quantitative and qualitative analysis of their composition in norm and pathology for a statistically significant sample of donors.     

The electrical activity of the dorsal wall of the rat trachea]

It was demonstrated that changes in the diameter of respiratory pathways during respiration process are associated with the activity of the plain muscles of the walls. Formation of this activity in a form of potential groups during inspiration phase is realized by the peripheral nervous apparatus. Co-ordination of the activity of this apparatus with the work of the respiratory center is realized via efferent vagal fibres.     

Entrainment of respiratory rhythm to respiratory oscillations of arterial PCO2 in vagotomized dogs.

The aim of this study was to demonstrate that the medullary respiratory rhythm generator is capable of entraining to respiratory oscillations of arterial PCO2 (CO2 oscillations). We used 10 anesthetized, paralyzed, vagotomized, and mechanically ventilated dogs. First, rate of mechanical ventilation was manually adjusted so that it matched the dog's spontaneous respiratory rate, which established a constant phase relationship between the mechanical ventilation and the burst of phrenic neurogram (initial phase). Then this phase relationship was temporally disturbed by a brief electrical stimulation of the superior laryngeal nerve (SLN). In the control group, the initial phase and the steady-state phase relationship after SLN stimulation were randomly distributed within the phase plane, implying no interaction between the respiratory center and mechanical ventilation. In contrast, when CO2 output from the lung was increased 2.6-fold above the control level by venous CO2 loading, the initial phase and the steady-state phase after SLN stimulation were locked in such a way that the onset of the burst of phrenic neurogram coincided with the peak of CO2 oscillations. This was not demonstrated when the dog was made hyperoxic. We therefore conclude that the respiratory center could entrain to phasic chemical afferent inputs originating from CO2 oscillations, provided they are considerably amplified.     

The interaction of quinone analogues with wild-type and ubiquinone-deficient yeast mitochondria

The interaction of the exogenous quinones, duroquinone (DQ) and the decyl analogue of ubiquinone (DB) with the mitochondrial respiratory chain was studied in both wild-type and a ubiquinone-deficient mutant of yeast. DQ can be reduced directly by NADH dehydrogenase, but cannot be reduced by succinate dehydrogenase in the absence of endogenous ubiquinone. The succinate-driven reduction of DQ can be stimulated by DB in a reaction inhibited 50% by antimycin and 70-80% by the combined use of antimycin and myxothiazol, suggesting that electron transfer occurs via the cytochrome b-c1 complex. Both DQ and DB can effectively mediate the reduction of cytochrome b by the primary dehydrogenases through center o, but their ability to mediate the reduction of cytochrome b through center i is negligible. Two reaction sites for ubiquinol seem to be present at center o: one is independent of endogenous Q6 with a high reaction rate and a high Km; the other is affected by endogenous Q6 and has a low reaction rate and a low Km. By contrast, only one ubiquinol reaction site was observed at center i, where DB appears to compete with endogenous Q6. DB can oxidize most of the pre-reduced cytochrome b, while DQ can oxidize only 50%. On the basis of these data, the possible binding patterns of DB on different Q-reaction sites and the requirement for ubiquinone in the continuous oxidation of DQH are discussed.     

Respiratory Reactions in Rats to Microinjections of Bombesin into the Region of the Nucleus Tractus Solitarius

In experiments on 35 mongrel albino rats, we studied the effects of a neuropeptide, bombesin (0.2 l, concentrations from 10^-13 to 10^-4), which was injected into the nucleus tractus solitarius, on the pattern of respiration and on the electrical activity of the main inspiratory muscles. The local influence of bombesin on this region of the respiratory center led to the expressed intensification of respiration. The respiratory volume and the amplitude of respiratory EMG bursts (oscillatory volleys in the diaphragmatic and external intercostal muscles), as well as the integral intensity of pulmonary ventilation, increased. The maximum deviations of these indices developed under the influence of the peptide in the intermediate concentrations (10^-10 to 10^-7 M). The observed reactions were characterized by short latencies, rapid development (2 to 5 min long), and relatively short duration. The data obtained are indicative of the possibility of direct involvement of the tested neuropeptide (bombesin) in the control of respiration and confirm concepts on the important role of the dorsal structures of the respiratory center in realization of respiratory effects of neuropeptides.     

Nervous control of respiration

Century-old notions on and formulations of the principle of external respiration control are discussed. The development of the main views on the mechanisms of action of individual nervous structures involved in respiratory control and their contributions is analyzed. A generalized scheme of the respiratory system control is proposed, according to which this autonomic and somatic system is composed of strictly defined afferent, central, and efferent components and is an open, multiextremal, adaptive, self-learning system based on a hierarchical principle. Ultimately, under any conditions of the vital activity of the body, the main regulator of the system (the respiratory center) optimally performs both deviation and perturbation control.     

Seasonal Dynamics of the Airborne Bacterial Community and Selected Viruses in a Children’s Daycare Center

Children’s daycare centers appear to be hubs of respiratory infectious disease transmission, yet there is only limited information about the airborne microbial communities that are present in daycare centers. We have investigated the microbial community of the air in a daycare center, including seasonal dynamics in the bacterial community and the presence of specific viral pathogens. We collected filters from the heating, ventilation, and air conditioning (HVAC) system of a daycare center every two weeks over the course of a year. Amplifying and sequencing the 16S rRNA gene revealed that the air was dominated by Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes that are commonly associated with the human skin flora. Clear seasonal differences in the microbial community were not evident; however, the community structure differed when the daycare center was closed and unoccupied for a 13-day period. These results suggest that human occupancy, rather than the environment, is the major driver in shaping the microbial community structure in the air of the daycare center. Using PCR for targeted viruses, we detected a seasonal pattern in the presence of respiratory syncytial virus that included the period of typical occurrence of the disease related to the virus; however, we did not detect the presence of adenovirus or rotavirus at any time.