Evaluation of the flow characteristics of an internal thoracic artery graft after coronary artery bypass grafting by intercostal Duplex scanning ultrasonography.

AIM: We previously reported intercostal duplex scanning ultrasonography to be a reliable technique for the evaluation of the internal thoracic artery (ITA). The purpose of this study was to determine the flow characteristics of the ITA graft using this technique. METHODS: We evaluated the flow characteristics of 69 ITA grafts who underwent coronary artery bypass grafting by this technique. The internal diameter, mean systolic and diastolic velocity, total flow volume and diastolic fraction were all thus obtained. RESULTS: One occluded graft was found during the follow-up. The mean systolic velocity significantly decreased after the operation (P=0.0001) and the mean diastolic velocity significantly increased both just after the operation (P=0.0002) and 1 year later (P=0.0283). The average diameter of the ITA graft after the operation (1.70+/-0.39), at 1 year (1.73+/-0.29) and at 2 years thereafter (1.66+/-0.27 mm) all significantly decreased in comparison to the preoperative value (2.30+/-0.35 mm) (P=0.0001). The average total flow volume after the operation (35.8+/-22.2), and at 1 year (29.4+/-16.5) and 2 years thereafter (23.4+/-12.7), respectively, were significantly decreased in comparison to the preoperative value (59.4+/-28.6 mL/min) (P=0.0001). However, the average diastolic fraction which was 25.1+/-10.5% before the operation significantly increased after the operation (54.5+/-12.0, 53.2+/-11.2 at 1 year and 50.4+/-9.3 at 2 years) (P=0.0001). CONCLUSION: This technique is thus considered to be a useful noninvasive for the postoperative follow-up of the graft function. A significant increase in the diastolic fraction is thought to be important for maintaining long term graft patency.

Repair of double outlet right ventricle with doubly-committed ventricular septal defect.

OBJECTIVE: To investigate our surgical results of intraventricular rerouting in patients having double outlet right ventricle with doubly-committed ventricular septal defect. METHODS: We undertook repair in 8 patients with this particular feature. Of these, 2 patients had pulmonary stenosis, and another had interruption of the aortic arch. The subarterial defect was unequivocally related to both the aortic and the-pulmonary orifices in all, albeit slightly deviated towards the aortic orifice in one, and towards the pulmonary orifice in another. Intraventricular rerouting was carried out via incisions to the right atrium and the pulmonary trunk. To ensure reconstruction of an unobstructed pulmonary pathway, a limited right ventriculotomy was made in 5. RESULTS: All patients survived the procedure, and are currently doing well, with follow-up of 25 to 194 months, with a mean of 117+/-68 months. Catheterization carried out 16+/-6 months after repair demonstrated excellent ventricular parameters. Mean pulmonary arterial pressure was 16+/-7 mmHg, being higher than 20 mmHg in 2 patients. No significant obstruction was found between the right ventricle and the pulmonary arteries. A pressure gradient across the left ventricular outflow tract became significant in one patient in whom a small outlet septum was present, and a heart-shaped baffle had been used for intraventricular rerouting. Reoperation was eventually needed in this patient for treatment of the obstruction, which proved to be progressive. CONCLUSION: Precise recognition of the morphologic features is of paramount importance when choosing the optimal options for biventricular repair in patients with double outlet right ventricle and doubly-committed interventricular communication.

Hepatocytic cells form bile duct-like structures within a three-dimensional collagen gel matrix.

It has been suggested that hepatocytes have the ability to form bile ductal structures during normal development and in various pathological conditions of the liver. In the present study, we attempted to establish an in vitro model of ductal morphogenesis of hepatocytic cells by combining an aggregate culture and a type I collagen gel culture. When spheroidal aggregates of rat or mouse primary hepatocytes were embedded within the collagen gel matrix and then cultured with a medium containing a fibroblast-conditioned medium, the aggregates extended many dendritic processes composed of a trabecular arrangement of cells. Dendritic morphogenesis was also seen in embedded aggregates of immortal liver epithelia] cell lines, which spontaneously emerged during long-term cultures of mouse primary hepatocytes. A similar morphogenesis was induced by the presence of insulin in the medium. Although epidermal growth factor (EGF) and hepatocyte growth factor (HGF) showed only a small effect on the morphogenesis of most of the hepatocytic cells when used alone, these factors, especially EGF, enhanced the morphogenetic effect of insulin. Electron microscopical observations revealed luminal structures lined by microvilli within these dendritic processes, indicating ductal differentiation. Immunocytochemically, the dendritic processes were positive for cytokeratin 19, a marker for bile duct cells. On the other hand, an H-ras-transformed mouse liver epithelial cell line and rat hepatocellular carcinoma cell lines did not demonstrate the organized morphogenesis. Our results indicate that hepatocytic cells can produce bile duct-like structures in the presence of the type I collagenous matrix and soluble morphogenetic factors.

Indistinct cell cycle checkpoint after u.v. damage in H-ras-transformed mouse liver cells despite normal p53 gene expression.

Growth arrest after u.v. damage was investigated in C3H mouse primary cultured hepatocytes, spontaneously immortalized liver epithelial cells and their H-ras-transformed derivatives. All cells except for one of the transformed lines had the wild type p53 gene considered necessary for the G1-S checkpoint. Growth arrest and accumulation of p53 protein with an abnormally-extended half-life were observed after 8 J/m2 u.v. treatment in primary hepatocytes and immortalized cells, but the arrest was much less evident in H-ras-transformed cells, in spite of the presence of the wild type p53 gene and accumulation of p53. Thus, the signal transduction upstream of p53 in the p53-mediated G1-S checkpoint may be retained in these transformed cell lines, although its downstream signal transduction or a pathway totally independent of this system could be altered. The transformed cells showed a much wider distribution of chromosomal number as compared to normal and immortalized cells, indicating that progression from the immortal to transformed state is associated with chromosomal instability, together with much decrease in the cell cycle checkpoint function.

Infrequent loss of heterozygosity and mutation of the p53 gene in immortal and transformed mouse embryo fibroblasts.

Some of the progeny of isolated mouse embryo fibroblasts acquire the ability to grow indefinitely during cultivation, presumably through some mutational events. The relevance of p53 mutations and loss of heterozygosity to the mechanism of such immortal growth capability remains controversial. Since four bases in intron 1 of the p53 gene in C3H/HeJ mice are replaced by 13 different bases in DBA/2J mice, it is possible to distinguish maternal and paternal p53 alleles in the cells of F1 hybrids of these strains (C3D2F1) by electrophoresis of polymerase chain reaction fragments including the region. We established 23 spontaneously immortalized fibroblast cell lines from C3D2F1 mouse embryos and 29 transformed cell lines induced from one of the immortal cell lines, either by treatment with chemical carcinogens or by transfection with the c-Ha-ras gene. Of these 52 cell lines, only one, derived from fibroblasts unpassaged for 4 mo, showed p53 gene loss of heterozygosity and a structural alteration in the remaining allele. Our results demonstrated that p53 mutations are not a strict requirement for immortalization and transformation of mouse embryo fibroblasts in vitro.