Inhibition of the alpha1beta1 isoform of the Na, K-ATPase by 8-methoxycoumestrol without positive inotropic effect in human myocardium--novel aspects of cardiac glycoside pharmacology.

BACKGROUND: The Na,K-ATPase (NKA) is necessary for maintaining the resting membrane potential by transporting Na and K ions across the cell membrane. Although its 3 isoforms expressed in human heart (alpha1beta1, alpha2beta1, and alpha3beta1) possess similar biochemical properties, their specific functions in human tissues remain unknown. In our search for an isoform-specific agent, which can serve to identify isoform-specific functions, we examined 8-methoxycoumestrol in its ability to inhibit the NKA and to produce inotropism in connection with the possibility to identify the NKA isoform-specific functions. METHODS AND RESULTS: In radioligand binding experiments (membrane preparations of yeast expressing isoforms alpha1beta1, alpha2beta1, and alpha3beta1; backdoor phosphorylation; and [H]-ouabain, n = 3), 8-methoxycoumestrol (1-10 microM) produced no or only little inhibition of specific ouabain binding. However, when NKA activity of the alpha1beta1 isoform was measured in membrane preparations from human kidney (reduced form of nicotinamide adenine dinucleotide-coupled assay, n = 3), a concentration-dependent full inhibition of the activity was induced by 8-methoxycoumestrol (IC50: 90 +/- 97 nM), similar to that observed for classical cardiac glycosides digitoxin, digoxin, methyldigoxin, and beta-acetyldigoxin (IC50 = 287 +/- 190 nM, 409 +/- 171 nM, 282 +/- 482 nM, 587 +/- 135 nM, P > 0.05). However, unlike the classical cardiac glycosides, 8-methoxycoumestrol did not increase cardiac contractility of electrically stimulated human right atrial trabeculae. CONCLUSIONS: These results indicate that 8-methoxycoumestrol inhibits the human alpha1beta1 NKA by a mechanism different to that of cardiac glycosides. In addition, the inhibition of the alpha1beta1 NKA activity seems not sufficient to evoke positive inotropy in human trabeculae, indicating that either the positive inotropic effect of cardiac glycosides is not mediated via the alpha1beta1 isoform or the specific glycoside binding to alpha1beta1 is needed for positive inotropy.

Delta-glycated hemoglobin: a novel independent risk factor for cardiovascular events in patients without diabetes mellitus.

BACKGROUND: A single measurement of glycated hemoglobin (HbA1c) is a weak predictor for cardiovascular events in patients without Type 2 diabetes mellitus. We hypothesized that dynamic changes in HbA1c (Delta-HbA1c) would better predict cardiovascular outcome than a single value. METHODS: In 99 consecutive patients with stable coronary artery disease (CAD) and without diabetes mellitus who were seen twice in our outpatient clinic (4-6 months apart) in 1998, Delta-HbA1c (follow-up HbA1c--baseline HbA1c) was assessed. Between August and September 2007 (mean observation period 9.1 yr), patients and their physicians were contacted by telephone to evaluate the incidence of cardiovascular endpoints. The combined primary endpoint of our study was defined as the incidence of myocardial infarction, stroke or death from any cause. The endpoints were validated by chart review. RESULTS: Multivariate analysis demonstrated that the change of HbA1c between first and second examination in 1998 was the most powerful parameter for prediction of the combined primary endpoint in the next 9 yr. The hazard ratio was 5.03 [95% confidence interval (CI) 1.4-17.9] for any increase in HbA1c and 1.99 (95%CI 1.3-3.0) for an HbA1c increase of 0.3%. In addition, Kaplan-Meier survival analysis showed a significant association between endpoint-free survival and dynamic changes in HbA1c. CONCLUSIONS: Hence, changes in the glucometabolic milieu within 4-6 months calculated by the difference of two values of HbA1c affect the long-term prognosis of patients with CAD but without diabetes mellitus.

An increase in HbA1c after percutaneous coronary intervention raises the risk for restenosis in patients without Type 2 diabetes mellitus.

AIMS: The influence of dynamic changes in glycated haemoglobin (HbA(1c)) on restenosis after elective percutaneous coronary intervention (PCI) in patients without diabetes has not been analysed. Therefore, the rate of restenosis was investigated after elective PCI in 101 consecutive patients without diabetes mellitus in relation to dynamic changes of HbA(1c) levels. METHODS: Follow-up angiography was performed in all patients 4-6 months after intervention. RESULTS: Multivariate analysis demonstrated that the change in HbA(1c) between first and second coronary angiography was the most powerful metabolic parameter for prediction of restenosis. The odds ratio for restenosis was 3.0 (95% CI 1.0-9.0) for any increase in HbA(1c) and 1.9 (95% CI 1.1-3.5) for an HbA(1c) increase of 0.2%. CONCLUSIONS: Hence, chronic changes in the glucometabolic environment influence the incidence of restenosis after PCI in patients without diabetes.

Activation of the calcineurin/NFAT signalling cascade starts early in human hypertrophic myocardium.

Cardiac hypertrophy is an independent risk factor for heart failure. Recent studies on gene regulation of proteins have involved intracellular Ca2+ homeostasis. The Ca2+-sensitive phosphatase, calcineurin, is one potential regulator of the hypertrophic response, so we aimed to investigate the calcineurin-dependent signal pathway at different stages of hypertrophy in human myocardium. We found the calcineurin pathway to be significantly activated in hypertrophic compared with non-hypertrophic myocardium as demonstrated by increased calcineurin activity and expression of calcineurin A-beta and B, and GATA-4, and a shift of phosphorylated cytoplasmic NFAT-3 into the nucleus as dephosphorylated nuclear NFAT-3. There was a tendency for these changes to be more pronounced in the decompensated compared with the compensated hypertrophic myocardium. The present study provides evidence for significant activation of the Ca2+-triggered calcineurin pathway in hypertrophic humans. Already present in compensated hypertrophy it showed a tendency to a further increase following transition to decompensated hypertrophy.

Calcineurin independent development of myocardial hypertrophy in transgenic rats overexpressing the mouse renin gene, TGR(mREN2)27.

Myocardial hypertrophy is an independent risk factor for development of heart failure. The intracellular calcium homeostasis is altered in myocardial hypertrophy, and recent studies in animal models have confirmed an interaction between the Ca2+/calmodulin-dependent calcineurin signaling cascade and development of cardiac hypertrophy. There is evidence for the involvement of various pathways in development of hypertrophy. A transgenic rat model overexpressing the mouse renin gene, TGR(mREN2)27 has been shown to progress profound cardiac hypertrophy, possibly due to a monogenetic disorder. However, the exact mode of action is not known. To study a possible involvement of calcineurin and its downstream pathway in development of cardiac hypertrophy in this transgenic rat model we measured the protein expression of marker proteins of the calcineurin cascade (calcineurin, NFAT-3, GATA-4) and calcineurin phosphatase activity and GATA-4 DNA binding in TGR ( n=10) compared to age-matched Sprague-Dawley rats ( n=10). In our study there was no significant difference in calcineurin activity between the transgenic hearts and the hearts of Sprague-Dawley rats. Furthermore, we found neither an increase in protein expression of calcineurin B nor a rise in nuclear translocated NFAT-3 DU. Interestingly, the protein expression of GATA-4 and its DNA binding activity were significantly higher in hypertrophied myocardium than in control hearts. In transgenic rats overexpressing the mouse renin gene and thereby developing pronounced cardiac hypertrophy [TGR(mREN2)27] we thus found no activation of calcineurin or its downstream pathway. However, the expression of the transcriptional factor GATA-4 and its DNA binding activity were significantly increased in hearts of transgenic rats. Thus GATA-4 seems to be a marker of hypertrophy independently of calcineurin activation, possibly activated by various pathways.

In vivo uptake of azithromycin in human coronary plaques.

Ten patients with symptomatic coronary artery disease received oral azithromycin for 3 days and underwent directional atherectomy on the third day. Azithromycin was found in all plaque samples with a median concentration of 284 ng/ml (95% confidence interval 163 to 517 ng/ml).

The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease.

CONTEXT: Acute aortic dissection is a life-threatening medical emergency associated with high rates of morbidity and mortality. Data are limited regarding the effect of recent imaging and therapeutic advances on patient care and outcomes in this setting. OBJECTIVE: To assess the presentation, management, and outcomes of acute aortic dissection. DESIGN: Case series with patients enrolled between January 1996 and December 1998. Data were collected at presentation and by physician review of hospital records. SETTING: The International Registry of Acute Aortic Dissection, consisting of 12 international referral centers. PARTICIPANTS: A total of 464 patients (mean age, 63 years; 65.3% male), 62.3% of whom had type A dissection. MAIN OUTCOME MEASURES: Presenting history, physical findings, management, and mortality, as assessed by history and physician review of hospital records. RESULTS: While sudden onset of severe sharp pain was the single most common presenting complaint, the clinical presentation was diverse. Classic physical findings such as aortic regurgitation and pulse deficit were noted in only 31.6% and 15.1% of patients, respectively, and initial chest radiograph and electrocardiogram were frequently not helpful (no abnormalities were noted in 12.4% and 31.3% of patients, respectively). Computed tomography was the initial imaging modality used in 61.1%. Overall in-hospital mortality was 27.4%. Mortality of patients with type A dissection managed surgically was 26%; among those not receiving surgery (typically because of advanced age and comorbidity), mortality was 58%. Mortality of patients with type B dissection treated medically was 10.7%. Surgery was performed in 20% of patients with type B dissection; mortality in this group was 31.4%. CONCLUSIONS: Acute aortic dissection presents with a wide range of manifestations, and classic findings are often absent. A high clinical index of suspicion is necessary. Despite recent advances, in-hospital mortality rates remain high. Our data support the need for continued improvement in prevention, diagnosis, and management of acute aortic dissection.

[Functional long-term results after open cholesteatoma surgery and ossiculoplasty with allogenic ossicles in adulthood]. / Funktionelle Langzeitresultate nach offener Cholesteatomchirurgie und Ossikuloplastik mit allogenen Ossikeln im Erwachsenenalter.

BACKGROUND: Characteristic features of cholesteatoma of the middle ear are destruction of the bone and a high tendency for recurrent disease. The choice of surgical procedure is determined by audiological results and the rate of recurrent cholesteatoma. PATIENTS: One hundred fifty patients who underwent primary cholesteatoma surgery were investigated 3-5 years postoperatively. Preoperative and postoperative audiological results and rate of revision surgery were compared for the respective surgical procedures. All cholesteatomas were treated with an open surgical technique. The lateral attic walls and cholesteatomas were removed. RESULTS: Cholesteotoma recurred in 15 patients (10%). Primary reconstruction of the ossicular chain with a tympanoplasty (type III) was performed in 98 patients in the first operation. Approximately 80% of patients treated with a type III tympanoplasty had a maximum postoperative air-bone gap of 20 dB in the main speech range, depending on the frequency. In about 50% of patients, this value was 10 dB or less. Comparison of preoperative and postoperative conductive hearing loss between 250 Hz and 8000 Hz revealed an improvement (p < 0.05) of 10 dB (500 Hz, 3000 Hz, 4000 Hz) and 15 dB (250 Hz, 1500 Hz, 2000 Hz, 8000 Hz). CONCLUSIONS: In our opinion, a second look operation should be performed in cases where a large cholesteatoma cannot be removed with sufficient reliability. This applies especially to a cholesteatoma in the oval window. Here, we suggest second-look surgery after one year.

[Autologous tissue in initial type I and type III tympanoplasty operations in chronic suppurative otitis media]. / Autologes Gewebe bei Typ-I- und Typ-III-Tympanoplastikerstoperationen bei der chronischen Schleimhauteiterung.

We reviewed 192 patients who had been treated for chronic otitis media. All operations were carried out at the Department of Otolaryngology, University of Tübingen. No patient had a previous ear operation and revision operations were excluded. The observation period varied from a minimum of 1 year to a maximum of 4 1/2 years. The ossicular chain was partially destroyed in 43 ears (22.4%). Ossiculoplasty was performed using autologous ossicles. An inens was used in 31 ears and a malleus in 12 cases. The overall failure rate was 20.8%. Most recurrent perforations were found in middle-aged patients. Children had only a 14% incidence of recurrent perforations. Fascia was the material associated with the highest failure rate (28.6%). After using perichondrium 6.8% of the cases had recurrent perforations, whereas the perichondrium-cartilage transplant was not successful in 4.8%. Overall, 62.7% of the patients were found to have an air-bone gap of 10 dB or less at 1.5 kHz 3-6 months after surgery. An air-bone gap of 20 dB or less was found in 91.2% of the patients. The main problem seen in the patients with chronic otitis media was not reconstruction of the ossicular chain but a lasting closure of the tympanic membrane. The perichondrium-cartilage transplant permitted the best results and is now recommended especially for patients with unfavorable middle ear conditions. A long-lasting closure of the tympanic membrane was also found in children (< or = 15 years of age). For this reason we also recommend an early operation in order to allow children to lead a normal life.