Biomedical subjects

Stefan Frantz

Publications and source records attributed to Stefan Frantz.

24 records · Page 2Linked to original sources

PubMed2003

Effect of testosterone on post-myocardial infarction remodeling and function.

BACKGROUND: Men and women are differently affected by coronary artery disease, suggesting an important role of sex steroids. Moreover, testosterone (T) treatment is increasingly used in elderly males. Therefore, we examined effects of chronic anabolic T administration on left ventricular (LV) remodeling after myocardial infarction (MI). METHODS: Adult male rats were treated with intramuscular placebo, testosterone undecanoate (T), or were orchiectomized. After 2 weeks, animals underwent sham-operation (sham) or left coronary artery ligation. Left ventricular remodeling and function was assessed by serial magnetic resonance imaging (MRI) at weeks 2 and 8 and hemodynamic investigation at week 8. RESULTS: In sham operated animals T administration increased serum T levels and led to cardiac hypertrophy, but not to an upregulation of ANP mRNA. The alpha/beta-MHC ratio was significantly higher after T treatment due to an increase in alpha-MHC. As a potential mechanism for this "physiologic" form of hypertrophy, IGF-1 mRNA expression was significantly increased in T treated animals. After coronary artery ligation, infarct size and mortality were similar among the groups. Left ventricular hypertrophy was enhanced by T treatment. However, in vivo LV end-diastolic pressure and wall stress were decreased by T, whereas other hemodynamic parameters (mean arterial pressure, cardiac output, etc.) remained unchanged. CONCLUSION: Chronic anabolic T treatment led to a specific "physiologic" pattern of myocardial hypertrophy with a significant increase in LV weight, but without differences in ANP and with an upregulation in alpha/beta-MHC, possibly mediated by IGF-1. Testosterone treatment had no detrimental effects following MI. Reduced wall stress and LVEDP may even improve long-term outcome.

Animals↗

PubMed2003

Sustained activation of nuclear factor kappa B and activator protein 1 in chronic heart failure.

OBJECTIVE: Innate immune response proteins such as inflammatory cytokines, inducible nitric oxide synthase, and toll like receptors are implicated in myocardial depression and left ventricular (LV) remodeling after myocardial infarction (MI). Although all these innate immunity proteins share the downstream activation of the transcription factor NF-kappaB (nuclear factor kappa B) and activator protein 1 (AP-1), the involvement of NF-kappaB and AP-1 in LV remodeling has not been demonstrated so far. METHODS AND RESULTS: Nuclear translocation of NF-kappaB and AP-1 was studied by electrophoretic mobility shift assays and ELISA 10 weeks after large experimental MI in rats, the chronic phase of LV remodeling. In the non-infarcted myocardium of MI rats, NF-kappaB and AP-1 were significantly activated (2.5-fold) as compared to sham-operated animals. Immunohistochemistry demonstrated NF-kappaB activation mainly in cardiac myocytes. Treatment with the ACE (angiotensin converting enzyme) inhibitor trandolapril led to a further 2-fold increase in the activation of NF-kappaB and AP-1 when compared to placebo-treated animals with the same MI size (P<0.001). Human failing hearts explanted at the time of heart transplantation exhibited marked nuclear translocation of NF-kappaB in cardiac myocytes when compared to control hearts. NF-kappaB as well as AP-1 were both significantly activated in congestive heart failure due to ischemic or dilated cardiomyopathy. CONCLUSION: In experimental and human heart failure, both NF-kappaB and AP-1 are chronically activated in cardiac myocytes. These findings suggest an important involvement of NF-kappaB and AP-1 in the cardiac remodeling process.

Adult↗

PubMed2003

Targeted deletion of caspase-1 reduces early mortality and left ventricular dilatation following myocardial infarction.

Objective. - Mice with targeted deletion of caspase-1 (interleukin-1beta (IL-1beta)-converting enzyme) lack the active forms of IL-1beta and IL-18, two cytokines implicated in maladaptive ventricular remodeling following cardiac injury. We, therefore, investigated the extent of ventricular dilation in caspase-1-knockout (KO) mice. Methods and results. - Transthoracic echocardiography was performed at days 1, 4, and 9 following left anterior descending artery ligation in caspase-1-KO and wild-type (WT) control animals, including M-mode and short-axis imaging at both mid-papillary and apical levels. Although initial post-operative mortality was lower in KO than in WT animals (21.4% WT, 12.0% KO, P < 0.001), there was no difference in mortality between 24 h and 9 d (P = n.s.). Caspase-1 KOs exhibited significantly less mid-papillary ventricular dilatation at days 4 and 9 compared to day 1 post-myocardial infarction (MI) (P < 0.05). Caspase-1 KOs also had a marked (50%) reduction in the level of matrix metalloproteinase 3 (MMP-3), although no significant changes occurred in other MMPs or in tissue inhibitors of metalloproteinase 1 levels by immunoblot analysis. Although IL-beta plasma levels were not detectable, both IL-18 levels and the rate of apoptosis in remodeling, non-infarcted muscle were significantly higher in WT compared to caspase-1-KO animals.Conclusion. - Mice lacking caspase-1 exhibited both improved peri-infarct survival and a decreased rate of ventricular dilatation, possibly due in part to a decrease in MMP-3 activity, IL-18 production, and a reduction in the rate of apoptosis after experimental MI.

Animals↗

PubMed2002

Regulation of Toll-like receptor 4 expression in the lung following hemorrhagic shock and lipopolysaccharide.

The Toll-like receptor 4 (TLR4) has recently been shown to function as the major upstream sensor for LPS. In this study, a rodent model of lung injury following resuscitated hemorrhagic shock was used to examine the regulation of TLR4 gene and protein expression in vivo and in vitro. Intratracheal LPS alone induced a rapid reduction in whole lung TLR4 mRNA, an effect which is also observed in recovered alveolar macrophages. This effect appeared to be due to a lowering of TLR4 mRNA stability by approximately 69%. By contrast, while shock/resuscitation alone had no effect on TLR4 mRNA levels, it markedly altered the response to LPS. Specifically, antecedent shock prevented the LPS-induced reduction in TLR4 mRNA levels. This reversal was explained by the ability of prior resuscitated shock both to prevent the destabilization of TLR4 mRNA by LPS and also to augment LPS-stimulated TLR4 gene transcription compared with LPS alone. Oxidant stress related to shock/resuscitation appeared to contribute to the regulation of TLR4 mRNA, because supplementation of the resuscitation fluid with the antioxidant N-acetylcysteine reversed the ability of shock/resuscitation to preserve TLR4 mRNA levels following LPS. TLR4 protein levels in whole lung mirrored the changes seen for TLR4 mRNA. Considered in aggregate, these data suggest that levels of tlr4 expression are controlled both transcriptionally as well as posttranscriptionally through altered mRNA stability and that antecedent shock/resuscitation, a form of global ischemia/reperfusion, might influence regulation of this gene.

Animals↗

PubMed2002

A sebaceous tumor in a patient with acquired immunodeficiency syndrome.

The prevalence of cutaneous malignancies is higher in immunosuppressed patients. Here, we describe a case with a rapid growing and unusually large sebaceous tumor in a patient with acquired immunodeficiency syndrome. Sebaceous adenomas are commonly rare, benign tumors of sebaceous glands. An association of AIDS and a solitary, large sebaceous adenoma has not been described yet. This emphasizes the role of an intact immune system in the suppression of benign and malignant tumors. tubular adenoma; tumor; AIDS

Acquired Immunodeficiency Syndrome↗

PubMed2002

Nitric oxide, cell death, and heart failure.

Strong evidence links cardiomyocyte loss to the pathology of some forms of heart failure. Both necrotic and apoptotic modes of cell death have been invoked as the mechanism underlying progressive cardiomyocyte dropout. Nitric oxide (NO) has received particular attention as a candidate reactive oxygen intermediate that influences not only cardiac function, but also cell death elicited by both apoptotic and necrotic mechanisms. NO is produced by resident cardiac cells under stress, and is produced in large quantities by activated immune cells that infiltrate the injured heart. A review of the literature, however, reveals that the actions of NO on apoptotic cell death are complex, especially in the context of heart disease, and that the practical contribution of NO to cell death in heart disease is yet to be defined.

Apoptosis↗