Sex mismatch in heart transplantation is associated with increased number of severe rejection episodes and shorter long-term survival

BACKGROUND

Heart transplantation is the criterion standard for treating end-stage heart failure. Male sex of both the donor organ and the recipient is advantageous for survival, possibly owing to hemodynamic or immunologic reasons. The effect of sex mismatch on long-term survival in male heart transplant recipients is less known.

PATIENTS AND METHODS

In this prospective single-center study, we reviewed follow-up data for 57 sex-mismatched and 179 sex-matched men who underwent orthotopic heart transplantation between 1990 and 2002.

RESULTS

Median survival was significantly shorter in the sex-mismatched group (8.1 vs 12.9 years; P < .04). Subgroup analysis revealed that this was even more pronounced in male heart recipients with coronary artery disease (2.4 vs 12.9 years; P < .001). Female donor organs were significantly smaller (left ventricular end-diastolic diameter 49 vs 51 mm; P < .05), and recipients more often experienced clinically relevant episodes of cellular rejection during the first 3 months posttransplantation (International Society for Heart and Lung Transplantation grade 3, 5.6% vs 3.1%; P < .001). Global left ventricular function, and immunosuppressive and inflammatory parameters did not differ.

CONCLUSION

In male orthotopic heart transplant recipients, sex mismatch is associated with adverse outcome owing to increased number and severity of episodes of graft rejection.

Cyclo-oxygenase-2 overexpression is a feature of early and well-differentiated hepatocellular carcinoma with a favourable prognosis

AIMS

To determine the prognostic relevance of cyclo-oxygenase-2 (COX-2) expression in hepatocellular carcinoma (HCC) and its relationship to important clinicopathological parameters.

METHODS

A series of 196 patients with HCCs treated either by surgical resection (n = 106) or liver transplantation (n = 90) was investigated. Immunohistochemically confirmed COX-2 expression was correlated with a series of clinicopathologically relevant parameters as well as proliferative activity and apoptosis.

RESULTS

Overexpression of COX-2 correlated statistically with high histological tumour differentiation (p<0.001) and early TNM stage (p = 0.003). COX-2 overexpression was associated with lower apoptotic rates (p = 0.001), whereas proliferation activity did not differ significantly. In addition, COX-2 overexpression showed a significant correlation with favourable overall survival (p<0.001). In multivariate survival analysis, COX-2 expression qualified as an independent prognostic parameter (p = 0.030).

CONCLUSIONS

Overexpression of COX-2 in HCC indicates early-stage cancer with less aggressive tumour behaviour and constitutes an independent prognostic factor.

Role of osteopontin and CD44s expression for patients with hepatocellular carcinoma undergoing liver transplantation or resection

BACKGROUND

Detection of new biomarkers for hepatocellular carcinoma (HCC) is needed to estimate prognosis after liver transplantation (OLT) or hepatic resection. Osteopontin (OPN) is a secreted, calcium-binding, phosphorylated, acidic glycoprotein that is overexpressed in various cancers. Cluster differentiation 44 standard isoform (CD44s) is one of the primary receptors of OPN; it may contribute to metastatic tumor spread.

MATERIALS AND METHODS

Tumor tissue and surrounding hepatic parenchyma were obtained from 53 HCC patients who underwent liver resection. Their RNA was extracted from nitrogen-frozen tissues, and OPN mRNA levels were estimated by quantitative reverse transcription-polymerase chain reactions. Formalin-fixed, paraffin-embedded tissues were obtained from the same patients, and additionally from 60 OLT HCC patients to perform expression analysis for OPN and CD44s by standard avidin-biotin immunostaining methods.

RESULTS

Expression of OPN and CD44s was significantly higher among HCC compared with adjacent nontumor tissue. The OPN mRNA expression and protein abundance correlated positively; OPN overexpression was associated with high tumor grade. A positive correlation existed between OPN and CD44s expression; both proteins were significantly overexpressed in HCC lesions with positive lymph nodes. No significant correlation existed between patient survival and OPN and CD44s expression.

CONCLUSION

Expression of both OPN and CD44s in HCC is associated with advanced tumor stage, thus possibly contributing prognostic information when evaluated together with classical clinicopathological parameters.

Liver transplantation as a primary indication for intrahepatic cholangiocarcinoma: a single-center experience

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is not a widely accepted indication for orthotopic liver transplantation (OLT). The present study describes our institutional experience with patients who underwent transplantation for ICC as well as those with ICC who underwent transplantation with the incorrect diagnosis of hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Data corresponding to ICC patients were reviewed for the purposes of this study. Patients with hilar cholangiocarcinoma and incidentally found ICC after OLT for benign diseases were excluded from further consideration.

RESULTS

Among the 10 patients, 6 underwent transplantation before 1996 and 4 after 2001. Those who underwent transplantation in the early period had a preoperative diagnosis of inoperable ICC (n = 4) and ICC in the setting of primary sclerosing cholangitis (n = 2). In the latter period the subjects had a diagnosis of HCC in cirrhosis (n = 3) or recurrent ICC after an extended right hepatectomy (n = 1). Median survival was 25.3 months for the whole series and 32.2 months (range, 18-130 months) when hospital mortality was excluded (n = 3). Four patients are currently alive after 30, 35, 42, and 130 months post-OLT, respectively. Two patients died of tumor recurrence at 18 and 21 months post-OLT, respectively. One-, 3-, and 5-year survival rates were 70%, 50%, and 33%, respectively.

CONCLUSIONS

The role of OLT in the setting of ICC may be re-evaluated in the future under strict selection criteria and with prospective multicenter randomized studies. Potential candidates to be included are those with liver cirrhosis and no hilar involvement who meet the Milan criteria for HCC.

AKT and ERK1/2 signaling in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinomas (ICC) are neoplasms that originate from cholangiocytes and can occur at any level of the biliary tree. Surgical resection is the current therapy of choice for this highly aggressive cancer. However, the 5-year survival still is poor, with high recurrence rates. Due to the intrahepatic growth a significant proportion of patients present with advanced disease and are not candidates for curative surgery or transplantation. The existing palliative options are of limited benefit and there is a great necessity for novel therapeutic options. In this article we review the role of the phosphoinositide 3-kinase(PI3K)/AKT and extracellular regulated kinase (ERK) signaling pathways in ICC and present new data on the prognostic value of these protein kinases. Finally, we discuss future upcoming therapeutic options based on targeting these signaling pathways.

[Liver biopsy under guidance of multislice computed tomography: comparison of 16G and 18G biopsy needles]

BACKGROUND

Percutaneous cutting needle biopsy of focal liver lesions under CT guidance has established itself as a standard method. The purpose of this study was to evaluate which diagnostic quality can be achieved under guidance of multislice CT (MSCT) and with the use of different needle sizes.

METHODS

The data of 163 MSCT-guided core biopsies of focal liver lesions were evaluated. A 16G biopsy needle was used in 121 cases and an 18G needle in 42 cases.

RESULTS

The sensitivity, specificity, and accuracy for all biopsies were 93.3, 100.0, and 94.5%. The corresponding values were 97.2, 100.0, and 97.5% for the 16G needle and 78.6, 100.0, and 85.7% for the 18G needle, respectively. A definite histological diagnosis could be obtained in 90.0% of the cases (16G 94.0%, 18G 75.8%). These differences were statistically highly significant. Bleeding complications were recognized in seven biopsies (4.3%). In one patient a fatal bleeding occurred after the biopsy. Median biopsy duration was 27 min.

CONCLUSIONS

Core biopsy under MSCT guidance is a fast and very accurate method to obtain a histological diagnosis in focal liver lesions. The usage of a 16G needle in comparison to an 18G needle yielded a significantly higher rate of correct results with regard to differentiation between benign and malignant disease as well as establishing a definite histological diagnosis. For an accurate diagnosis of liver lesions a 16G needle is recommended. After biopsy, the patients have to be closely monitored.

Single-center experience on liver transplantation for hepatocellular carcinoma arising in alcoholic cirrhosis: results and ethical issues

BACKGROUND

Liver transplantation is currently recognized as the optimal treatment for both early hepatocellular carcinoma in the setting of cirrhosis (HCC) as well as for alcoholic liver disease (ALD). The purpose of this study was to evaluate the outcome of patients with HCC and ALD in the absence of viral hepatitic infections.

METHODS

Twelve recipients were transplanted with a diagnosis of HCC and ALD in the absence of viral hepatitis during a 6-year period. Nine received deceased donor livers, and 3 live donor grafts. Our results were compared to those obtained by a search of the world literature.

RESULTS

The postoperative course was uneventful in all but one patient. All recipients experienced a good quality of life postoperatively. Three-year overall and recurrence-free survival rates were 82 and 73%, respectively. Nine patients are currently alive, after a median follow-up of 29 months.

CONCLUSION

This is the first study to evaluate liver transplantation for HCC in ALD. Although outcomes are excellent, the evaluation of patients with ALD and HCC constitutes a challenging topic in transplantation surgery, especially when live liver donation is considered. An interdisciplinary structured approach is recommended, with special emphasis on ethical considerations.

Activation of extracellular regulated kinases (ERK1/2) but not AKT predicts poor prognosis in colorectal carcinoma and is associated with k-ras mutations

Signal transduction and modulation represent central mechanisms in cellular processes such as cell-cycle regulation, oncogenesis, and apoptosis. The aim of this study was to determine the prognostic relevance of two kinases important in the regulation of cell proliferation and apoptosis in 135 colorectal cancer cases: AKT and extracellular regulated kinases (ERK1/2). We investigated the relationship of phospho-ERK1/2 (pERK1/2) and phospho-AKT (pAKT) with associated parameters (EGFR, COX-2, cyclin-D1), proliferative activity (Ki-67), and apoptosis (TUNEL) using immunohistochemistry. Additionally, the k-ras gene was screened for mutations to determine its putative association with ERK1/2 activation. Activation of ERK1/2 but not AKT correlated statistically with the presence of k-ras mutations (P = 0.015). Survival analysis of phospho-ERK1/2 immunoexpression showed a significant correlation with decreased overall survival (OS). The multivariate Cox regression analysis identified pERK1/2 as an independent prognostic parameter (P = 0.005). Activation of ERK1/2 in colorectal cancer may indicate aggressive tumor behavior and may constitute an independent prognostic factor. Furthermore, our data suggest that mutations of the k-ras oncogene may induce activation of ERK1/2. We propose immunohistochemical determination of pERK1/2 status as a promising candidate for the identification of high-risk patients who would benefit from new anticancer drugs targeting the ERK pathway.

Ribavirin with either standard or pegylated interferon to treat recurrent hepatitis C after liver transplantation

AIM

To investigate the efficacy of two anti-viral protocols in hepatitis C virus-reinfected liver transplant recipients.

METHODS

In this prospective study, 26 liver transplant patients were treated with standard interferon-alpha2b for 12 months or standard interferon-alpha2b for 3 months followed by pegylated interferon-alpha2b for 9 months. Interferon was combined with ribavirin in all patients. The histological course of the study population was compared with an untreated historic control group (n = 38) with similar baseline characteristics.

RESULTS

The sustained virological response rates in the standard interferon group and in the pegylated interferon group were 27.3% and 26.7%, respectively. Only 29% of patients with sustained virological response had end of treatment histological response, whereas 47% of viral non-responders showed end of treatment histological response. The percentage of patients with histological improvement was significantly higher in the study population when compared to the controls. Univariate analysis indicated that hepatitis C virus genotype non-1, high baseline alanine aminotransferase, the time interval between liver transplant and interferon therapy and the body mass index predicted sustained virological response. In the multivariate model, baseline alanine aminotransferase and the body mass index remained a significant predictor of sustained virological response.

CONCLUSIONS

Both treatment regimens offer similar efficacy profiles. Failure to eradicate hepatitis C virus should not lead to treatment discontinuation if serial liver biopsies demonstrate histological response.

[Surgical therapy of intrahepatic cholangiocellular carcinoma]

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary hepatic malignancy. Tumor resection is the treatment of choice, but so far the value of hepatic resection has not been well defined. We report results with an aggressive surgical approach for the treatment of this tumor entity.

PATIENTS AND METHODS

Between April 1998 and June 2004, 54 liver resections were performed in 120 patients with ICC. In 24 patients, 39 additional procedures were performed: resection of hilar bifurcation (n=18), partial resection of diaphragm (n=6), vascular resection and reconstruction (n=15).

RESULTS

There were 30 R0, 21 R1, and three R2 resections. After R1/R2 resection and explorative laparotomy, the median survival times are 9 months and 6 months, respectively. Following R0 resection, the calculated median survival is 46 months, and the 1-, 3-, and 5-year survival rates are 83%, 58%, and 48%, respectively.

CONCLUSION

The presented data show that R0 resection leads to a significant prolongation of survival in patients with ICC. In contrast, incomplete tumor removal does not provide a survival benefit. These results justify an aggressive surgical approach to achieve a R0 resection. The low resectability rate of less than 50% underlines the need for improved preoperative staging.

Overexpression of cyclo-oxygenase-2 is an independent predictor of unfavourable outcome in node-negative breast cancer, but is not associated with protein kinase B (Akt) and mitogen-activated protein kinase (ERK1/2, p38) activation or with Her-2/neu signalling pathways

BACKGROUND AND AIM

The production of prostaglandins is regulated by cyclo-oxygenases (COXs), which also have a role in tumour development and progression in various malignancies, including breast cancer. The mechanisms by which COX-2 contributes to unfavourable prognosis are still poorly understood. The association between expression of COX-2 and possible linked signalling pathways-namely, Akt, extracellular regulated kinases (ERK1/2), the stress-activated kinase p38 or Her-2/neu-is assessed in a series of 113 node-negative breast cancers.

RESULTS

COX-2 was identified as an independent prognostic factor (p = 0.034) in node-negative breast cancer by survival analysis. The lack of a relationship between COX-2 expression and activated Akt, Erk1/2, p38 and Her-2/neu was indicated by statistical analysis.

CONCLUSIONS

The prognostic effect of COX-2 expression on lymph node-negative breast cancer is confirmed-COX-2 is probably not regulated by HER-2, Akt, Erk1/2 or p38. Further studies are necessary for the elucidation of the signalling pathways responsible for the modification of COX-2 expression and the increased aggressiveness of breast cancers overexpressing COX-2.

Disease course after liver transplantation for hepatocellular carcinoma in patients with complete tumor necrosis in liver explants after performance of bridging treatments

AIM

To study the disease course of patients with hepatocellular carcinoma (HCC) showing complete tumor necrosis in their liver explants after undergoing bridging treatments followed by liver transplantation (LTx).

PATIENTS AND METHODS

We evaluated data corresponding to 10 patients with liver cirrhosis undergoing bridging treatments for HCC prior to LTx. In all cases there was complete tumor necrosis in the explanted livers.

RESULTS

There were 8 men and 2 women. Percutaneous radiofrequency ablation (RFA) was performed under computed tomographic guidance in 4 patients. The remaining 6 patients underwent transarterial chemoembolization (TACE). Five of them received one session of TACE, while the remaining one received a series of 4 sessions prior to LTx. Six patients had solitary nodules with a median diameter of 3.5 cm (range 2.5-4.2 cm). Four of them underwent RFA. Segmental tumor chemoembolization was performed in 2 patients. The remaining 4 patients had 2 tumors each with a median total diameter of 4.4cm (range 4.2-6.0 cm) prior to TACE. They underwent bilobar hepatic chemoembolization, which under staged the tumors prior to live donor liver transplantation (LDLTx). Six patients underwent deceased donor orthotopic liver transplantation. LDLTx was performed in 4 patients. Median waiting time to LTx was 53 days. All patients are alive without recurrence after a median follow-up of 19 months.

CONCLUSION

Achievement of 100% tumor necrosis by means of bridging treatments followed by LTx for HCC is characterized by a very low recurrence rate and should receive further consideration and study.

Relationship and prognostic significance of phospho-(serine 166)-murine double minute 2 and Akt activation in node-negative breast cancer with regard to p53 expression

The Akt signalling pathway plays a central role in tumourigenesis. Activation of Akt is related to a more aggressive phenotype in various human cancers, including breast cancer. Its activation contributes to cancer progression via pleiotropic effects, including suppression of apoptosis and modulation of cell cycle regulation. Murine double minute 2 (MDM2) is an oncoprotein that inhibits the function of p53 tumour suppressor protein. Cell culture studies show that Akt-related phosphorylation of MDM2 at serine 166 allows MDM2 to gain nuclear entry and fulfil its p53 regulating function. This study was designed to analyse the relationship of phospho-MDM2 (pMDM2) expression with Akt activation to determine a possible prognostic relevance of pMDM2 in node-negative breast cancer with respect to Akt activation and p53 status. pMDM2, phospho-Akt (pAkt) and p53 protein expression status were analysed immunohistochemically in 121 paraffin-embedded breast cancer cases. Expression of pMDM2 correlated with Akt activation (P<0.001). Univariate analysis identified pMDM2 as a prognostic factor (P=0.0458) in node-negative breast cancers. The unfavourable prognostic significance was even more pronounced in tumours with a pMDM2(+)/pAkt(+) immunophenotype (P=0.0205). Stratification into a p53-negative subgroup further strengthened the adverse prognostic influence. These data confirm that MDM2 phosphorylation at serine 166 is mediated by Akt kinase. Besides the prognostic impact of pMDM2, our findings suggest that Akt-mediated modulation of the MDM2/p53 complex contributes to increased tumour aggressiveness especially in p53-negative breast cancers. However, due to the relatively small number of patients in this cohort, the results obtained need to be confirmed by larger cohorts.

[Two cystic retroperitoneal lesions mimicking adrenal cysts]

Adrenal cysts are uncommon lesions and most of them are found incidentally during abdominal imaging. We report on two benign extraadrenal lesions mimicking adrenal tumors in abdominal imaging. The histopathological investigation of the lesions revealed a foregut duplication cyst of the lesser gastric curvature and an epithelial inclusion cyst (epidermoid cyst) in an intrapancreatic accessory spleen respectively.

ETV6–NTRK3 gene fusion in a secretory carcinoma of the breast of a male-to-female transsexual

Secretory carcinomas of the breast were first described as "juvenile carcinoma" by McDivitt and Stewart in a cohort of children. This term has been replaced by the term "secretory breast carcinoma", because the entity can occur at any time of life. Carcinoma of the male breast is uncommon and accounts for approximately 1% of all cancers in men. Recently, it has been reported that human secretory breast carcinoma expresses the ETV6-NTRK3 gene fusion that was previously cloned in pediatric mesenchymal cancers. We present the case of a 46-year-old male-to-female transsexual in whom a secretory breast carcinoma was an incidental finding. As confirmation of the histopathological diagnosis we detected the novel ETV6-NTRK3 gene fusion in this tumor.

Immunohistochemical differentiation of eosinophilic heart diseases using antibodies against eosinophil activation markers

AIMS

Eosinophilic heart syndromes are rare in Western countries and include endocarditis parietalis fibroplastica (EPF) and hypersensitivity myocarditis (HM). There are striking differences in natural history and morphological findings. Since diagnosis can be difficult when analysing small myocardial biopsies lacking the characteristic histological features, we studied a set of immunohistochemical markers in order to characterize the activation status of the infiltrating eosinophils to distinguish between these two entities.

METHODS AND RESULTS

This study is based on the investigation of seven explanted hearts and one left ventricular specimen collected during implantation of a left ventricular assist device from a total of seven patients with HM. Also investigated were three right and three left ventricular specimens from five patients with EPF. We used antibodies (Ab) against EG1, and EG2, CD44, and CD69 which have been described as markers to distinguish between resting and activated eosinophils. The EG1 to EG2 ratio of eosinophils and the immunoreactivity against CD44 showed no differences between the two entities. However, eosinophils in the EPF were completely negative for CD69, whereas eosinophils reacted positively within the HM group.

CONCLUSION

The immunohistochemical investigation of eosinophilic heart diseases using antibodies against CD69 can be a useful tool to distinguish between hypersensitivity myocarditis and endocarditis parietalis fibroplastica.

[Left ventricular assist devices (LVAD): optional treatment alternative to cardiac transplantation?]

Left ventricular assist devices (LVAD) are used to "bridge" patients with end-stage heart failure until transplantation of a donor heart can be performed ("bridge to transplantation"). However, LVAD support sporadically results in improved cardiac function, and heart transplantation is not necessary even after removal of LVAD in a subset of patients ("bridge to recovery"). Additionally, LVAD appears to be an optional treatment alternative to heart transplantation in patients with contraindication for organ replacement ("destination therapy"). The underlying process has descriptively been termed "reverse remodeling". The molecular basis remains incompletely understood at present, however, some mechanisms have been identified in the past. Alterations of several molecular pathways are involved in the development of chronic heart failure. Some of the pathways appear to be reversible and have been shown to be regulated by LVAD treatment. LVAD lead to lowered cardiac pressure and volume overload followed by decreased ventricular wall tension, reduction of cardiomyocyte hypertrophy, improved coronary perfusion and a decrease of chronic ischemia in the myocardium. Improved coronary flow and myocardial perfusion as well as decreased ventricular wall tension may serve as a possible explanation for changes of the molecular systems involved in the development of chronic cardiac insuffiency. This review focuses on the roles of apoptosis, heme-oxygenase-1 (HO-1), Metallothionein (MT) and the transcription factor NFkkappaB in chronic heart failure after mechanical circulatory support.

[Myocardial alterations with mechanical left ventricular assist devices]

Left ventricular assist devices (LVAD) have been used to "bridge" patients with end-stage heart failure to transplantation. Although several reports have suggested that the native ventricular function recovers after long-term LVAD support, a process called "reverse remodeling", the underlying biological mechanisms are still unclear. Various molecular pathways of the human myocardium associated with apoptosis, response to stress, or matrix changes are known to be altered under conditions of heart failure, and some have been shown to be reversibly regulated during left ventricular mechanical support, suggesting that the descriptive term "reverse remodeling" is, at least in parts, a reversible mechanism. The reduction of volume and pressure overload with a decrease of ventricular wall stress leading to an improvement of myocardial blood supply under mechanical circulatory assistance, may be one explanation for the molecular myocardial changes and may reflect one possible cause for the phenomenon of "reverse remodeling".

Uniform long-term gene expression using adeno-associated virus (AAV) by ex vivo recirculation in rat-cardiac isografts

BACKGROUND

Gene therapy in cardiovascular disease promises to be of great impact. The ideal vector for the therapeutic gene transfection remains to be determined. The aim of the present study was to investigate the efficacy of gene transfer using adeno-associated virus vectors carrying the lacZ-reporter gene (AAV-lacZ) in a previously described coronary recirculation model.

METHODS

Beating Lewis rat hearts perfused with oxygenated Krebs-Henseleit solution were harvested, after which an atrial septal defect (ASD) was created. All vessels were tied, and AAV-lacZ was injected into the aortic root. The solution was recirculated through the ASD to the left side of the heart and pumped back to the coronary arteries by the left ventricle. Incubation was allowed for 20 min at 15 degrees C, and the hearts were subsequently transplanted heterotopically in syngeneic rats. Three increasing doses (109, 1,010, 1,011 e. u.) of AAV-lacZ virus vectors were used to study the rate of gene transfer. All hearts were harvested after 7-60 days and evaluated histologically for expression of the lacZ-gene.

RESULTS

Dose-dependent gene transfer was observed. Even after 60 days, there was no obvious decline in gene expression.

CONCLUSION

Adeno-associated virus vectors offer effective and uniform gene transfer in the myocardium after transcoronary injection and recirculation. Due to the lack of immune response previously described, no decrease in gene expression can be observed up to 60 days after injection.

[Primary Burkitt lymphoma of the heart--diagnosis and therapy]

An 85-year-old patient suffered from progressive deterioration (NYHA III) for several months. Cardiac disease was suspected. Echocardiography as well as a CT scan of the heart revealed a heart tumor to be the cause. Tumor staging was negative. After transvenous biopsy, the diagnosis of a Burkitt lymphoma could be established. Due to the advanced age of the patient, the intended surgical therapy was turned down and the patient was treated with 6 courses of a potentially therapeutic chemotherapy (CHOP scheme), which was well tolerated by the patient. The following CT scan showed a complete remission of the tumor. Six months after chemotherapy the patient is in NYHA stage I.

Progressive cardiac hypertrophy and dysfunction in atrial natriuretic peptide receptor (GC-A) deficient mice

OBJECTIVE

To investigate how permanent inhibition of guanylyl cyclase A receptor (GC-A) affects cardiac function.

METHODS

Hearts of GC-A-/- and corresponding wild type mice (GC-A+/+) were characterised by histological, western blotting, and northern blotting analyses. Cardiac function was evaluated in isolated, working heart preparations.

RESULTS

At 4 months of age, GC-A-/- mice had global cardiac hypertrophy (about a 40% increase in cardiac weight) without interstitial fibrosis. Examination of heart function found a significant delay in the time of relaxation; all other parameters of cardiac contractility were similar to those in wild type mice. At 12 months, the hypertrophic changes were much more severe (about a 61% increase in cardiac weight), together with a shift in cardiac gene expression (enhanced concentrations of atrial natriuretic peptide (3.8-fold), B type natriuretic peptide (2-fold), beta myosin heavy chain (1.6-fold) and alpha skeletal actin (1.7-fold) mRNA), increased expression of cytoskeletal tubulin and desmin (by 29.6% and 25.6%, respectively), and pronounced interstitial fibrosis. These changes were associated with significantly impaired cardiac contractility (+dP/dt decreased by about 10%) and relaxation (-dP/dt decreased by 21%), as well as depressed contractile responses to pressure load (all p < 0.05).

CONCLUSIONS

Chronic hypertension in GC-A-/- mice is associated with progressive cardiac changes--namely, initially compensated cardiomyocyte hypertrophy, which is complicated by interstitial fibrosis and impaired cardiac contractility at later stages.