AMP-deaminase from human term placenta.

AMP-deaminase from human term placenta was chromatographed on a phosphocellulose column and physico-chemical and immunological properties of the purified enzyme were investigated. At physiological pH 7.0, in the absence of regulatory ligands (control conditions) studied AMP-deaminase manifested sigmoid-shaped substrate saturation kinetics, with half-saturation parameter (S0.5) value of about 7 mM. Addition of important allosteric effectors (ATP, ADP or orthophosphate) modified kinetic properties of studied AMP-deaminase, influencing mainly the value of S0.5, parameter. Micromolar concentrations of stearylo-CoA inhibited potently the enzyme making it no longer sensitive towards 1 mM ATP-induced activation. SDS-PAGE electrophoresis of the purified enzyme revealed presence of 68 kDa protein fragment, reacting with anti-(human) liver AMP-deaminase antibodies. Experimental results presented indicate that 'liver type' of AMP-deaminase is an enzyme form present in human term placenta.

Experimental pancreatitis induced by synthetic prooxidant tert-butyl hydroperoxide.

The purpose of this study was to verify whether injection of tert-butyl hydroperoxide (Bu(t)OOH, a well-known prooxidant agent) into the bile-pancreatic duct can induce acute pancreatitis. A rapid blockade of the secretion was observed in the majority of the animals after 3 hours of observation. After 6 hours, the secretion reached a very low level, significantly different compared with controls. In groups of rats injected with Bu(t)OOH, pancreatic weight gain was observed compared with the rats injected with physiologic saline. Histology of pancreata removed 3 hours after injection of Bu(t)OOH showed acinar cell vacuolization, interstitial edema, focal necrosis of pancreatic acini, fat-tissue necrosis, and leukocyte infiltration of the organ. These changes were considerably greater after the 6-hour observation period. Electron-microscopic inspection revealed profound morphologic changes 3 hours after Bu(t)OOH injection. The control rats receiving physiologic saline alone had well-preserved pancreatic tissue structure. In conclusion, injection of the prooxidant agent, tert-butyl hydroperoxide, into common bile-pancreatic duct induces acute necrotizing pancreatitis, which indicates the crucial role of free radical reactions in pathogenesis of this disease.

Structural-functional relationships in pig heart AMP-deaminase in the presence of ATP, orthophosphate, and phosphatidate bilayers.

The secondary structure of pig heart AMP-deaminase (AMP-d) in the absence and in the presence of orthophosphate or dioleoyl phosphatidic acid (DOPA) or ATP was investigated by FT-IR spectroscopy. While the latter substance activates the enzyme, orthophosphate is a well-known negative allosteric effector and DOPA exerts a noncompetitive inhibition on AMP-deaminase. Small changes in the secondary structure of AMP-d were induced by the above mentioned substances. Only DOPA reduced the thermal stability of AMP-d and avoided protein intermolecular interactions suggesting structural-functional relationships in AMP-d in the presence of the above substances and a possible role of phosphatidic acid in the subtle regulation of AMP-d activity by temporary binding of the enzyme to cellular membranes.

The assessment of hypertrophy of nasopharyngeal tonsil by acoustical methods.

The possibilities for using acoustical analysis as a noninvasive measure of the degree of obstruction created by an enlarged pharyngeal tonsil (adenoid) are discussed. The method capitalizes on the relationship which exists between a specific obstruction of the respiratory tract and the resulting respiratory sound. Results indicate that as the adenoid increases in size relative to the size of the nasopharynx, the dominant components of the respiratory sound spectrum shift towards a higher frequency range. Furthermore, the correlation found between the assessments of the obstruction due to various sizes of the adenoid by radiological methods and acoustical analyses supports the theoretical prediction that information on the size of the constriction is carried by the respiratory sound. Therefore, careful analyses of the acoustic patterns in the respiratory sound can assist in identifying constrictions and monitoring the constriction changes in the upper respiratory tract.

The interaction of phospholipid bilayers with pig heart AMP deaminase: Fourier-transform infrared spectroscopic and kinetic studies.

The interaction of pig heart AMP deaminase with different chemical species of phosphatidylcholine and with natural plasma membranes has been investigated. Phospholipids added to the system either as natural biological membranes (plasma membrane vesicles) or in the form of liposomes containing unsaturated phosphatidylcholine considerably enhanced AMP deaminase activity. The secondary structure of pig heart AMP deaminase in the absence and in the presence of dioleoyl phosphatidylcholine and dipalmitoyl phosphatidylcholine liposomes was investigated by Fourier-transform infrared spectroscopy. Quantitative analysis of the amide I band showed that the enzyme contains 45% beta-sheets, 28% alpha-helix, 16% turns and 11% non-ordered structure. In the presence of dioleoyl phosphatidylcholine liposomes, the beta/alpha content ratio decreased; this decrease was dependent on the amount of lipid added. This phenomenon was not observed in the case of dipalmitoyl phosphatidylcholine liposomes. These data suggest a possible role for membrane phospholipids in the regulation of AMP deaminase activity.

The influence of phosphatidate bilayers on pig heart AMP deaminase. Crucial role of pH-dependent lipid-phase transition.

Phosphatidate bilayers composed of dilauroylphosphatidate, dimyristoylphosphatidate, dipalmitoylphosphatidate and dioleoylphosphatidate were prepared. Their interaction with AMP deaminase isolated from pig heart was investigated. Dioleoylphosphatidate bilayers were found to exert non-competitive inhibition on the AMP deaminase with a Ki of 15 x 10(-6) M. This inhibition is three orders of magnitude stronger than that exerted by orthophosphate. The phosphatidate species containing saturated fatty acids were either non-inhibitory or inhibited enzyme activity rather poorly. However, alkalinization of the medium from pH 6.5 to pH 7.9 led to the inhibition of pig heart AMP deaminase by dilauroylphosphatidate bilayers. This was accompanied by the fluidization of the saturated phosphatidate species, i.e. the lowering of their phase transition temperature in alkaline pH, as measured by light-scattering and fluorescence scans. The possible significance of these findings for the regulation of AMP deaminase activity in vivo by natural membranes is discussed.

Diversity of the effect of phosphatidylcholine and sphingomyelin on adenylate deaminase from pig brain.

Liposomes made of sphingomyelin were found to inhibit both ATP-activated and non-activated AMP deaminase from pig brain, in contrast to liposomes made of egg yolk phosphatidylcholine which exhibited an activating effect on the ATP-activated enzyme, being without effect on AMP deaminase in the absence of ATP. Dioleoylphosphatidylcholine exerted a similar effect as egg yolk phosphatidylcholine but dipalmitoylphosphatidylcholine was without effect.

Treatment of post-intubation laryngotracheal stenosis.

Post-intubation laryngotracheal stenosis in children is an important therapeutic problem in pediatric otolaryngology. The numbers of children treated by prolonged intubation and resuscitated children are increasing. In the Department of Pediatric Otolaryngology in Warsaw, 6 children were treated for post-intubation laryngotracheal stenosis. In the treatment the method of longitudinal intralaryngotracheal incisions was applied; in 3 cases with tracheotomy followed by cellophane separation and in 3 cases without the use of separator and without tracheotomy. There were no complications connected directly with the operation. Pneumonia was a frequent later complication making treatment difficult. Good therapeutic results were obtained.

Prenatal and neonatal prophylaxis in otorhinolaryngology.

Congenital malformations and diseases in the region of the ear, nose, throat, larynx and lower respiratory tract, have their source in genetic disorders and exogenous noxious factors influencing the development of the embryo, fetus and newborn child. The authors discuss the possibilities of prophylaxis during pregnancy, the perinatal period and the first days of life.

Results of surgical treatment of choanal atresia.

During a period of 19 years we have treated 65 infants with choanal atresia. Thirty of them showed a bilateral atresia, thirty-five a unilateral (29 left-sided, 6 right-sided). Fifty patients were girls, fifteen boys. In 27 cases the abnormality was combined with other anomalies. Most infants have been operated upon in the first six months of their life by a transpalatinal approach in general anethesia. From the results the following conclusions can be made: early treatment is the method of choice; restoration of nasal permeability, although minimal, allows normal nutrition and diminishes a number of respiratory infections, due to choking. The transpalatinal approach permits a direct control of the surgical area. It does not inhibit the growth of the hard palate and the function of the soft palate. Failures are caused by difficulties to keep the new passage open.

[On the physiopathologic reactions of pharyngeal tonsil from the clinical standpoint (author's transl)]. / Uber die physiopathologischen Reaktionen der Rachentonsille vom klinischen Standpunkt

On the basis of personal experiences the authors isolate two forms of pharyngeal tonsil hypertrophy: a physiological and a pathological one. The first one corresponds to the requirements of the organism which is not completely mature immunologically, it may be quite considerable but causes no disturbances in breathing through the nose or in the function of Eustachian tubes. The pathological hypertrophy of pharyngeal tonsil is due to a parenchymal inflammation caused by viruses with a typical pathogenesis. The authors describe six diagnostic criterias of the pathological hypertrophy of pharyngeal tonsils. Using these criter as they analysed 100 cases of adenotomy from the year 1969 and they have found that in only 38 cases the operation was done for pathological hypertrophy while in 62 cases hypertrophy was physiologic. Adentomy gives good results in cases of pathological hypertrophy but in cases of physiologic hypertrophy it may cause adverse results.

[Evidence of viral aetiology in exudative otitis media in childhood (author's transl)]. / Versuch eines Bewieses für die Virusätiologie bei der exsudativen Mittelohrentzündung im Kindesalter

Many clinical observations point to a primary viral cause in exudative otitis media. This seromucinous inflammation may then develop into a purulent inflammatory phase as a result of subsequent bacterial infection. The aetiology of otitis media may thus be viral, viral bacterial or bacterial. Viruses and bacteria multiply in a different manner within the organism. They also give rise to different defence reactions and physical signs of their different pathogenic effects. Viral otitis is characterised by proliferative tissue changes, such as telangiectatic granulations, adhesions, cholesteatomas and limitation of pneumatisation of the mastoids. Destructive tissue damage is predominant in bacterial infections, e.g., tympanic perforations and bone destruction. 100 children were examined virologically during acute exudative otitis media and in the presence of a cholesteatoma. Viral aetiology was proved in many cases and viral antigens were demonstrated in the cholesteatomatous material.