The Sydney Heart Bank: improving translational research while eliminating or reducing the use of animal models of human heart disease

The Sydney Heart Bank (SHB) is one of the largest human heart tissue banks in existence. Its mission is to provide high-quality human heart tissue for research into the molecular basis of human heart failure by working collaboratively with experts in this field. We argue that, by comparing tissues from failing human hearts with age-matched non-failing healthy donor hearts, the results will be more relevant than research using animal models, particularly if their physiology is very different from humans. Tissue from heart surgery must generally be used soon after collection or it significantly deteriorates. Freezing is an option but it raises concerns that freezing causes substantial damage at the cellular and molecular level. The SHB contains failing samples from heart transplant patients and others who provided informed consent for the use of their tissue for research. All samples are cryopreserved in liquid nitrogen within 40 min of their removal from the patient, and in less than 5-10 min in the case of coronary arteries and left ventricle samples. To date, the SHB has collected tissue from about 450 failing hearts (>15,000 samples) from patients with a wide range of etiologies as well as increasing numbers of cardiomyectomy samples from patients with hypertrophic cardiomyopathy. The Bank also has hearts from over 120 healthy organ donors whose hearts, for a variety of reasons (mainly tissue-type incompatibility with waiting heart transplant recipients), could not be used for transplantation. Donor hearts were collected by the St Vincent's Hospital Heart and Lung transplantation team from local hospitals or within a 4-h jet flight from Sydney. They were flushed with chilled cardioplegic solution and transported to Sydney where they were quickly cryopreserved in small samples. Failing and/or donor samples have been used by more than 60 research teams around the world, and have resulted in more than 100 research papers. The tissues most commonly requested are from donor left ventricles, but right ventricles, atria, interventricular system, and coronary arteries vessels have also been reported. All tissues are stored for long-term use in liquid N or vapor (170-180 °C), and are shipped under nitrogen vapor to avoid degradation of sensitive molecules such as RNAs and giant proteins. We present evidence that the availability of these human heart samples has contributed to a reduction in the use of animal models of human heart failure.

Histopathologic and immunophenotypic characterization of extramedullary plasmacytomas in nine cats

To contribute to the existing body of knowledge in the literature on the apparently rare extramedullary plasmacytoma in cats, lymphoid tumors with plasmacytic cellular morphology taken from nine cats were examined. The paraffin-embedded material was investigated by standard hematoxylin and eosin, and special staining techniques (Giemsa, Congo-red, and periodic acid-Schiff reaction). The tumors also were examined immunohistochemically for the presence of immunoglobulin G, immunoglobulin A, immunoglobulin M, immunoglobulin light chains (lambda, kappa), various amyloid proteins, and FeLV-antigen (p27 protein). An immunoglobulin-producing tumor of plasmacellular origin (extramedullary plasmacytoma [EMP]) could be diagnosed in all cases on the basis of immunohistochemical light-chain expression. All but one of the neoplasms occurred in the skin of older, predominantly male cats. As in humans and dogs, the following types could be identified according to their morphologic features: mature type (two), cleaved type (two), asynchronous type (four), and polymorphous type (one). The tumor tissue of three cats revealed amyloid deposits, which were immunohistochemically diagnosed as ALlambda-amyloid in all three cases.

Crataegus extract blocks potassium currents in guinea pig ventricular cardiac myocytes

Crataegus extract is used in cardiology for the treatment of mild to moderate heart failure (NYHA II) in Germany. However, little is known about the electrophysiological actions of Crataegus extract in the heart. Recently, it was shown that Crataegus extract prolongs the refractory period in isolated perfused hearts and increases action potential duration in guinea pig papillary muscle. It was the aim of this study to find out the mechanism of the increase in action potential duration caused by Crataegus extract. Using the patch-clamp technique, we measured the effects of Crataegus extract (10 mg/l; flavonoid content: 2.25%, total procyanidin content: 11.3 +/- 0.4%) on the inward rectifier and the delayed rectifier potassium current in isolated guinea pig ventricular myocytes. To get some insight into the mechanism underlying the positive inotropic effect of Crataegus extract, we also looked for effects on the L-type calcium current. Crataegus extract slightly blocked both the delayed and the inward rectifier potassium current. The inhibition amounted to 25% and about 15%, respectively. This amount of inhibition of these repolarising currents is sufficient to explain the prolongation of action potential duration caused by Crataegus extract. To our surprise we could not detect any influence of Crataegus extract on the L-type calcium current. In summary, our results show that Crataegus extract blocks repolarising potassium currents in ventricular myocytes. This effect is similar to the action of class III antiarrhythmic drugs and might be the basis of the antiarrhythmic effects described for Crataegus extract. Our measurements of the L-type calcium current indicate that Crataegus extract's positive inotropic effect is not caused by phosphodiesterase inhibition or a beta-sympathomimetic effect.

Actions of the antiarrhythmic peptide AAP10 on intercellular coupling

Disturbances in gap junction distribution and a decrease in the connexin43 content of the heart were shown to occur after myocardial infarction and in ischemic heart disease, respectively. These changes are now thought to play an important role in the genesis of arrhythmias associated with these diseases. It is thought that agents that can increase cellular coupling might be beneficial in these situations. Recently, we presented data showing that the synthetic peptide AAP10 acts antiarrhythmically in a model of regional ischemia. The data suggested that AAP10 might act via an increase in cellular coupling. The goal of this study was to establish whether AAP10 can interact with cardiac gap junctions. Measurements of the stimulus-response-interval (SRI) in guinea pig papillary muscle showed that high concentrations of AAP10 (1 microM) can decrease the SRI by about 10% under normoxic conditions. At lower concentrations (10 nM) AAP10 had no effect on SRI under normoxic conditions but prevented the increase in the SRI induced by perfusion with hypoxic, glucose-free Tyrode's solution. Double-cell voltage-clamp experiments confirmed that AAP10 can interact with cardiac gap junctions. 10 nM AAP10 could either diminish or reverse the run-down of gap junction conductance normally observed in pairs of guinea pig ventricular myocytes. During control gap junction conductance decreased with a rate of -2.5 +/- 2.0 nS/min. After application of 10 nM AAP10 gap junction conductance increased with a rate of +1.0 +/- 0.7 nS/min (p < 0.01). After washout of AAP10 gap junction conductance decreased again with a rate not significantly different from control. Our results show that AAP10 does interact with gap junctions. Because no other effects of AAP10 on other electrophysiological parameters could be found, this action on gap junctions might be the basis of AAP10's antiarrhythmic effect seen in previous studies.

Increase in gap junction conductance by an antiarrhythmic peptide

Impaired cellular coupling is thought to be a very important factor for the genesis of cardiac arrhythmia. Cellular coupling is mediated by gap junctions. However, there are no therapeutic agents or experimental substances yet that increase cellular coupling. In addition, it has been shown that most antiarrhythmic drugs available now possess serious adverse effects. Thus, there is an urgent need for new antiarrhythmic agents. Previous studies using epicardial mapping in isolated rabbit hearts provided indirect evidence supporting the hypothesis that a newly synthesised antiarrhythmic peptide (Gly-Ala-Gly-4Hyp-Pro-Tyr-CONH2 = AAP10) might act via an increase in cellular, i.e., gap junctional coupling. The aim of the present study was to test this hypothesis. Measurement of the stimulus-response interval in papillary muscle showed a decrease of about 10% after application of 1 microM AAP10. These results are compatible with the hypothesis of AAP10 acting on gap junctions. In order to prove this hypothesis, gap junction conductance was measured directly by performing double-cell voltage-clamp experiments in isolated pairs of guinea-pig myocytes. During a 10 min control period gap junction conductance slowly decreased with a rate of -2.5 +/- 2.0 nS/min. After application of 10 nM AAP10 this behaviour reversed and gap junction conductance now increased with +1.0 +/- 0.7 nS/min. Upon washout of AAP10 gap junction conductance again decreased with a rate similar to that under control conditions. Another important finding was that we could not detect any other actions of AAP10 on cardiac myocytes. All parameters of the transmembrane action potential remained unchanged and, similarly, no changes in the IV relationship of single cardiac myocytes treated with 10 nM AAP10 could be observed. We conclude that AAP10 increases gap junction conductance, i.e., cellular coupling in the heart. This finding might be the first step towards the development of a new class of antiarrhythmic agents.

Estimation of trends of mortality rates in selected industrialized countries

"The first part of the...paper [compares]....mortality trends of various age groups in twelve selected industrialized countries..., covering the period from the beginning of the 50s until 1980/81.... Essential changes regarding the age-group specific mortality trends will be [outlined]....An estimation of trends of age-group specific mortality rates in the selected countries will be presented in the second part of this paper.... The trend and the levels of the estimated mortality rates as well as the comparison between the selected countries will be described." Rates are presented separately for males and females.