Truncus arteriosus communis associated with interrupted aortic arch: a report on two uncommon cases.

The paper presents two infants with the A-4 type of truncus arteriosus communis (according to Van Praagh's classification). One patient who survived a surgical procedure demonstrated a rare variant of aortic arch interruption to the left off the left subclavian artery (type A according to Celoria and Patton), whereas the second presented an uncommon anomaly in which the right subclavian artery originated from the descending aorta with associated severe truncal valve incompetency. The authors describe the clinical picture along with the surgical treatment of the first infant who being six days old was subjected to a correction employing the wide patent ductus arteriosus to reconstruct the aortic arch, following the method described by Gomes and McGoon. Subsequently an aortic homograft was implanted in order to connect the right ventricle and the pulmonary artery.     

Response of the right ventricle to progressive pressure loading in pigs

Summary The purpose of this study was to determine the speed and duration of progressive pressure loading of the right ventricle to systemic pressure levels, which allows right ventricular adaptation without myocardial impairment at rest.In 8 pigs with an average weight of 22 kg progressive right ventricular pressure loading of different speeds and durations was induced with a newly developed constrictor. Pressures in the right atrium, right ventricle, and pulmonary artery as well as angiocardiographic volume parameters of the right ventricle were determined weekly over a period of 4 to 7 weeks. A fast progressive right ventricular pressure increase of 3.4 mm Hg/day during 3 weeks was associated with a 20–30% reduction of ejection fraction and a 100% increase of the end-systolic volume. Increase of end-diastolic pressure was 3 to 5 fold. A slow progressive pressure increase of 1.5 to 2.2 mm Hg/day to 100 mm Hg within 4 to 5 weeks was associated with an increase of the end-diastolic pressure to a level observed in systemic ventricles, while change of ejection fraction and end-systolic volume was minimal. The faster the increase of right ventricular pressure the flatter was the peak systolic pressure/end-systolic volume relationship.It is concluded that in contrast to sudden and fast progressive increase of afterload slow progressive increase of afterload to systemic levels does not impair right ventricular myocardial function.This study was supported by: Deutsche Forschungsgemeinschaft-grant HE 769/6-2     

Assessment of myocardial salvage after ischemia and reperfusion using magnetic resonance imaging and spectroscopy

To test the hypothesis that contrast-enhanced magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) can differentiate reversible from irreversible myocardial injury, these modalities were used to study ischemia and reperfusion in a rat model. The presence of ischemia and reperfusion were confirmed with radiolabeled microspheres (n = 6). Groups of animals were subjected to either 16 (n = 17), 30 (n = 14), 60 (n = 11), or 90 (n = 14) minutes of left coronary artery (LCA) occlusion and 60 minutes reperfusion. After albumin-gadolinium (Gd)-DTPA injection, contrast-enhanced, T1-weighted, spin-echo proton images were acquired at baseline and every 16 minutes during LCA occlusion and reperfusion. In separate experiments, 31phosphorus (31P) spectra were acquired at similar time points during ischemia and reperfusion. After 16 minutes occlusion, normally perfused myocardium enhanced significantly compared with ischemic myocardium on MRI (104 +/- 7.9% vs. 61 +/- 11.0%, p less than 0.05, n = 5, mean +/- SEM, % of baseline value). MRS showed reduced phosphocreatine (PCr) and adenosine triphosphate (ATP) (58.8 +/- 2.4%, p less than or equal to 0.01; 81.4 +/- 2.4, p less than or equal to 0.01, n = 12). After 16 or 30 minutes ischemia, reflow resulted in uniform MRI signal intensity of the ischemic zone compared with normal myocardium (93.5 +/- 11.3 vs. 80.9 +/- 7.0, p = NS, n = 11, % of baseline value at 30 minutes reperfusion) and PCr recovery on MRS (94.3 +/- 4.0%, p = NS, n = 20, % baseline value at 30 minutes reflow). After 60 and 90 minutes ischemia, reflow resulted in marked enhancement of reperfused compared with normal myocardium on MRI (254.0 +/- 30.0 vs. 78.3 +/- 9.2, p less than or equal to 0.01, n = 10) and no recovery of PCr on MRS (64.1 +/- 3.0, p = NS, n = 14). Triphenyltetrazolium chloride (TTC) staining revealed transmural myocardial infarction (MI) in all hearts subjected to 60 or 90 minutes ischemia and reflow, and small nontransmural MIs in only 2/11 hearts subjected to 16 or 30 minutes ischemia and reperfusion. Thus, 1) MRI with albumin-Gd-DTPA is useful for identifying myocardial ischemia by enhancing the contrast between normally perfused and ischemic myocardia; 2) MRI with albumin-Gd-DTPA is useful for identifying reperfusion after myocardial ischemia; and 3) after reperfusion, reversible can be distinguished from irreversible myocardial injury by characteristic findings on MRI and MRS.     

Discrete microstructural cues for the attenuation of fibrosis following myocardial infarction

Chronic fibrosis caused by acute myocardial infarction (MI) leads to increased morbidity and mortality due to cardiac dysfunction. We have developed a therapeutic materials strategy that aims to mitigate myocardial fibrosis by utilizing injectable polymeric microstructures to mechanically alter the microenvironment. Polymeric microstructures were fabricated using photolithographic techniques and studied in a three-dimensional culture model of the fibrotic environment and by direct injection into the infarct zone of adult rats. Here, we show dose-dependent down-regulation of expression of genes associated with the mechanical fibrotic response in the presence of microstructures. Injection of this microstructured material into the infarct zone decreased levels of collagen and TGF-β, increased elastin deposition and vascularization in the infarcted region, and improved functional outcomes after six weeks. Our results demonstrate the efficacy of these discrete anti-fibrotic microstructures and suggest a potential therapeutic materials approach for combatting pathologic fibrosis.     

Microangiopathic Haemolytic Anaemia Associated with Hypercakaemia in an Experimental Rat Tumour

A severe microangiopathic haemolytic anaemia develops during the course of tumour growth in rats bearing the solid Walker carcinosarcoma 256. Early changes of blood coagulation are the prolongation of the clotting and clot-forming time in the thrombelastogram, a reduction of factor-VIII activity and impaired platelet aggregation. Subsequent decrease of plasma fibrinogen and blood platelets indicate intravascular coagulation as the cause of the haematological changes. Fibrinogen turnover studies with homologous ¹³¹I-fibrinogen showed a significantly shortened half time. Concomitant with the alterations of the clotting mechanism a decrease of plasminogen level as well as an increasingly prolonged euglobulin lysis time were found; these may be interpreted as the result of the fibrinolytic response to intravascular fibrin deposition. Histological examination of the animals' organs demonstrated fibrin strands and large fibrin thrombi exclusively in the capillaries of the tumour. Simultaneously with the intravascular coagulation syndrome the animals develop a hypercalcaemia caused by a parathyroid hormone-like substance elaborated by the tumour tissue. Since clinical reports point to an interrelation between thrombotic disorders and hyperpara-thyroidism, the possible role of hypercalcaemia in triggering intravascular coagulation is briefly reviewed.     

胃癌腹膜种植瘤动物模型的构建

目的建立稳定实用的人胃癌鼠腹膜种植瘤模型。方法通过对裸鼠和SCID鼠腹腔注射胃癌细胞株AGS、NCI—N87和SNUl6构建腹膜种植瘤模型,比较不同细胞株模型成功率和生存期的差异。结果裸鼠腹腔种植5×106个AGS、NCI—N87和SNUl6细胞腹膜瘤形成率分别是（3／8、6／8和2／8;SCID鼠腹腔种植5×106个AGS、NCI—N87和SNUl6细胞,腹膜瘤形成率分别是0／6、6／6和6／6。SCID鼠腹膜瘤模型中位生存期：NCI—N87细胞组（10x10。）为74d;SNUl6细胞3个不同剂量组（10×106、20×106和40×106）分别为95、78和44d。结论SCID鼠腹腔种植（20—40）×106个SNUl6细胞可以构建稳定实用的胃癌腹膜种植瘤模型。