[The effect of mechanical support of the heart on the extent of experimental myocardial necrosis. I]. / Vliv mechanické podpory srdce na rozsah experimentální nekrózy myokardu. I. cást.

The authors investigated the influence of mechanical cardiac support with a non-pulsating blood flow on the size of an ischaemic after ligature of the descendent branch of the left coronary artery in the dog. As compared with a control group of experimental animals where mechanical cardiac support was not used, the size of the necrotic focus of the heart muscle diminished by 50% (p less than 0.01). In some of the experimental animals the size of the necrotic focus did not change despite the use of a mechanical cardiac support. Analysis of haemodynamic parameters (assessed and calculated) revealed that for the fate of the necrotic focus of the myocardium the degree of relief (decompression) of the left ventricle is decisive. In complete relief the necrosis diminishes in size.

[Possibilities of limiting myocardial infarct in an experiment]. / Moznosti omezení infarktu myokardu v experimentu.

A total of 31 dogs were investigated with the aim to evaluate possibilities of pharmacological reduction of ischaemic perfusion damage of the heart muscle. In the experiment two-hour complete ischaemia was used (ligature of the ramus interventricularis anterior) and a subsequent two-hour period of reperfusion. The magnitude of the infarction focus evaluated as the percentage of the ischaemic risk area, using the triphenyltetrazolium method, extended by colour detection of collaterals, was evaluated. Furthermore the authors also evaluated the prevalence of ventricular dysrhythmias in the reperfusion period. In a group of 10 dogs treated by N-acetylcysteine, 100 mg per kg body weight, the authors revealed on comparison with 11 dogs of the control group a diminution of the infarction focus by 32.7%. By addition of Panthenol, 50 mg/kg to N-acetylcysteine in another 10 dogs, a diminution of the infarction by 49% was achieved. The magnitude of the infarction focus was 55.0 +/- 7.0% in the control group, 37.0 +/- 12.6% in dogs treated with N-acetylcysteine (p less than 0.01) and 28.0 +/- 13.3% after administration of N-acetylcysteine and Panthenol (p, as compared with control, again less than 0.01). N-acetylcysteine reduces also significantly the prevalence of ventricular dysrhythmias in the reperfusion period. As compared with the control group this difference is most marked after 60 minutes have elapsed following release of the ligature (p less than 0.001).

The phosphate pool of isolated dog heart during global ischaemia: comparison of two cardioplegic solutions with 31P NMR spectroscopy.

31P NMR spectroscopy was used to study the time course of changes in the concentration of high-energy metabolites and intracellular pH in the dog myocardium during hypothermic ischaemia at 9 degrees C in Bretschneider (HTK-B) and St. Thomas' Hospital (StTH) cardioplegic solutions. It was found that ATP and phosphocreatine degrade slowlier in HTK-B than in StTH, with phosphocreatine depletion occurring within 7.9 +/- 1.4 h in HTK-B and within 6.2 +/- 1.4 h in StTH. The values are virtually identical with the time intervals at which ATP concentration falls below the critical level (60% of initial ATP concentration). In agreement with biochemical analysis, a higher concentration of phosphomonoesters was noted until the 180th minute of ischaemia in HTK-B, a finding suggesting more rapid glycogen degradation in HTK-B. Even though HTK-B contains a high concentration of histidine buffer, higher values of intracellular pH were found during ischaemia in StTH. The effect of extracellular concentration of sodium ions on intracellular pH is discussed.

Cardioprotective effects of N-acetylcysteine: the reduction in the extent of infarction and occurrence of reperfusion arrhythmias in the dog.

We have studied the cardioprotective effect of N-acetylcysteine in the dog. In mongrel dogs of either sex, the left anterior descending coronary artery was ligated for a period of 2 hours behind the origin of its first diagonal branch. After this period, dogs in a treated group were administered 100 mg of N-acetylcysteine/kg body weight while a control group remained untreated. This was followed by a 2-hour period of reperfusion. The extent of necrosis was determined using the triphenyltetrazolium method. Presence or absence of collaterals was established at the same time. The incidence of ventricular arrhythmias was monitored throughout the study. Compared with 11 dogs of the control group, 10 dogs treated with N-acetylcysteine showed a decrease of 32.7% in the extent of infarction. The extent of infarction, expressed as the percentage of the left ventricular myocardium at risk, was 55.0 +/- 7.0% in the control group and 37.0 +/- 12.6% in the treated group (P less than 0.01). N-acetylcysteine also statistically significantly decreased the incidence of ventricular arrhythmias over the period of reperfusion. Compared with the control group, the difference was evident as early as the first 5-10 minutes of reperfusion, becoming most pronounced at the 60th minute (P less than 0.001). We conclude that N-acetylcysteine is effective in limiting the extent of infarction and significantly reduces the incidence of reperfusion ventricular arrhythmias.

Erythromycin hepatotoxicity. A rare cause of a false-positive technetium-99m DISIDA study.

An unusual cause of a cholescintigraphic, false-positive, erythromycin-induced hepatotoxicity is presented. This occurred in the presence of preservation of hepatic uptake and the normal appearance of gut activity. Serial scintigraphy and serum chemistries documented underlying gallbladder normalcy.

Effect of mercurascan on the contractility and excitability of dog papillary muscle in vitro.

The authors studied in 6 experimental series the effect of Mercurascan (2-hydromercurifluorescein and 4-hydroxymercurifluorescein) on isolated dog papillary muscle in vitro; they evaluated the magnitude and character of its electrically stimulated contractions. It was found that at concentration of 10(-3)M and 10(-4) M, Mercurascan (MSC) exerts a significant positive inotropic effect on papillary muscle. Incubation of the muscle in a medium containing MSC at the above-given concentrations significantly suppressed the positive inotropic and arrhythmogenic effect of adrenalin, added in an over-threshold dose into the nutrient medium.

Indications and experimental preparatory studies for pancreas transplantation.

Clinical and experimental evidence support the metabolic aetiology of diabetic microangiopathy. This paves the way for its management by transplantation of endocrine pancreas. In an informative article, the authors attempts to conceptualize their position concerning indications for pancreas transplantation and offer a review of their own experimental studies, a prerequisite before actual clinical application.

[Changes in the pancreas after obliteration of the pancreatic ducts in a dog with Hydron]. / Zmeny pankreatu po obliteraci pankreatických vývodu u psa Hydronem.

The development of pancreatic changes was studied after obliteration of pancreatic ducts by means af 2-hydroxyethylmethacrylate. The drug was injected into the main pancreatic duct of 15 dogs that were put to death successively and examined by histology. Necrosis of pancreatic duct epithelium was found in 4 days after the polymer administration in addition to focal periductal necrosis of acinar tissue and interstitial oedema with fibroblast activation. Later, a rapid development of fibrosis occurred which ensue in an extinction of exocrine tissue after 2 months. Pancreas consisted then but of connective tissue and cumulated Langerhans' islets with positive beta-granulations. Pancreatic ducts obliteration is a reliable method for selective inhibition of exocrine activity.

Segmental transplantation of the pancreas with and without the ligation of the duct in dogs.

The autotransplantation of a pancreas segment with ligated duct to cervical vessels, autotransplantation and allotransplantation of a pancreas segment with unligated duct to iliac vessels were carried out in three groups of dogs. The occurrence was followed of the hemorrhagic necrosis and of their complications. When ligating the duct, the mortality and the rate of occurrence of hemorrhagic necrosis were of 54 and 77% respectively. In grafts with an open duct into the abdominal cavity, for the autotransplantation the mortality and occurrence of the hemorrhagic necroses were of 33%, for the allotransplantation the mortality and autodigestion were of 11 and 45%, respectively. The cause of the hemorrhagic necrosis in animals with unligated duct of the graft was most probably represented by a hematoma. The graft rejection was characterized by an asymptotic course without damaging the recipient. The transplantation method with open duct into the abdominal cavity is promising for the clinical application.