ABSTRACT
The channel-forming activity of gramicidin A derivatives carrying positively charged amino acid sequences at their C-termini was studied on planar bilayer lipid membranes and liposomes. We showed previously that, at low concentrations, these peptides form classical cation-selective pores typical of gramicidin A, whereas, at high concentrations, they form large nonselective pores. The ability of the peptides to form nonselective pores, which was determined by the efflux of carboxyfluorescein, an organic dye, from liposomes, decreased substantially as the length of the gramicidin fragment in the series of cationic analogues was truncated. CD spectra showed that large pores are formed by peptides having both beta6.3 single-stranded and beta5.6 double-stranded helical conformations of the gramicidin fragment, with the C-terminal cationic sequence being extended. The dimerization of the peptides by the oxidation of the terminal cysteine promoted the formation of nonselective pores. It was shown that nonselective pores are not formed in membranes of erythrocytes, which may indicate a dependence of the channel-forming ability on the membrane type. The results may be of interest for the directed synthesis of peptides with antibacterial activity.
Subject(s)
Anti-Bacterial Agents/chemistry , Gramicidin/analogs & derivatives , Gramicidin/chemistry , Ion Channels/chemistry , Lipid Bilayers/chemistry , Amino Acid Sequence , Dimerization , Erythrocyte Membrane/chemistry , Gramicidin/chemical synthesis , Humans , Liposomes/chemistry , Peptides/chemical synthesis , Peptides/chemistry , PorosityABSTRACT
The effect of hypoxic-hypercapnic trainings (HHT), conducted before the induction of inflammation or started at next day after foreign body bringing, was shown in experiment on rats with chronic inflammation process in bronchopulmonary tissue. HHT conducted before the induction of inflammation in general had an favourable effect. HHT conducted later had a positive effect together with expressed negative changes, in particular worsening of inflammation process in lung.
Subject(s)
Bronchitis/immunology , Hypercapnia , Hypoxia , Lung/immunology , Physical Conditioning, Animal , Pneumonia/immunology , Animals , Bronchitis/physiopathology , Chronic Disease , Lung/physiopathology , Male , Pneumonia/physiopathology , Rats , Rats, WistarABSTRACT
The efficiency was studied of rehabilitation of 115 patients with chronic bronchitis engaged in agricultural work under the effect of a complex of traditional health-resort climatic factors as well as this complex supplemented by breathing exercises with additional dead space or intensified graded physical exercises (cycling, running). Only the therapeutic complex including physical exercises proved efficient.
Subject(s)
Agricultural Workers' Diseases/rehabilitation , Bronchitis/rehabilitation , Chronic Disease , Combined Modality Therapy , Health Resorts , Humans , UkraineABSTRACT
A study was made of ventilation and perfusion in 105 patients with chronic pulmonary nonspecific diseases using radiopneumography with 133Xe. A simultaneous macro-microangiographic study was made of the pulmonary artery on specimens taken after lobectomy in 35 patients with bronchiectasia in the lower lobe. The control group was composed of 35 specimens of the healthy lungs taken from unembalmed cadavers of people who died of diseases unrelated to the involvement of the respiratory system as well as from 30 healthy people after radiopneumography. Asymmetry of the distribution of ventilation and perfusion is typical of patients with bronchiectasia. It manifests itself in a significant decrease in the VLC and the blood flow in the affected zone. A simultaneous compensatory rise of perfusion was recorded. In a macro-microangiographic study a rough deformity of the vascular trunks at the level of the segmental and subsegmental vessels was marked in these patients; angles of the outgoing of vessels of the main trunk decreased significantly, the number of vessels with a winding course increased. Simultaneous anatomostructural radionuclide studies make it possible to understand more deeply the essence of a pathological process.
