Modulation of peripheral chemoreflex by neurohumoral adaptations after kidney transplantation

BACKGROUND

Peripheral chemoreceptors residing predominantly in the carotid body monitor changes in arterial blood oxygen and are mechanistically linked to the cardiorespiratory control by the autonomic nervous system. Enhanced sympathetic activation is common in end-stage renal disease and kidney transplantation has been shown to improve cardiorespiratory reflex measures of autonomic function.

OBJECTIVE

The aim of the present study was to test whether improvement in renal function following kidney transplantation is related to an improvement in chemosensory function.

METHODS AND RESULTS

We compared hyperoxic chemoreflex sensitivity (CHRS) in patients after renal transplantation (RTX) to that in patients on maintenance hemodialysis (HD), and that of age- and gender-matched healthy controls. In addition, we investigated the impact of common confounding factors including pharmacological neurohumoral modulation and diabetes mellitus. The difference in the R-R intervals divided by the difference in the oxygen pressures before and after deactivation of the chemoreceptors by 5-min inhalation of 7 L oxygen was calculated as the hyperoxic CHRS. Autonomic activity was characterized by 24-h time-domain heart rate variability (HRV) parameters. CHRS was improved in RTX patients as compared to HD patients being related to HRV. CHRS was related to the concomitant presence of diabetes and medication with cyclosporine.

CONCLUSION

Our findings indicate that chemosensory activity following kidney transplantation is related to cardiac autonomic control, but functional testing might only be useful to characterize the time course and extent of sympathetic activation in selected patients due to existing co-morbidities and immunosuppressive medication in this population.

Sequential analysis of uncommon adverse outcomes

Sequential analysis of uncommon adverse outcomes (AEs) such as surgical site infections (SSIs) is desirable. Short postoperative lengths of stay (LOS) result in many SSIs occurring after discharge and they are often superficial. Deep and organ space (complex) SSIs occur less frequently but are detected more reliably and are suitable for monitoring wound care. Those occurring post-discharge usually require readmissison and can be counted accurately. Sequential analysis of meticillin-resistant Staphylococcus aureus bacteraemia is also needed. The key to prevention is to implement systems based on evidence, e.g. using 'bundles' and checklists. Regular mortality and morbidity audit meetings are required and these may need to be followed by independent audits. Sequential statistical analysis is desirable for data presentation, to detect changes, and to discourage tampering with processes when occasional AEs occur in a reliable system. Tabulations and cumulative observed minus expected (O-E) charts and funnel plots are valuable, supplemented in the presence of apparent 'runs' of AEs by cumulative sum analysis. Used prospectively, they may enable staff to visualise and detect patterns or shifts in rates and counts that might not otherwise be apparent.

[Cardiac effects of obstructive sleep apnea]

Sleep disordered breathing, especially obstructive sleep apnea, are common in cardiovascular disease. Negative hemodynamic effects are mediated by nocturnal ischemia and intrathoracal pressure swings. Therefore "therapy resistant" arterial hypertension and congestive heart failure, as well as atrial fibrillation or sleep associated bradycardia are suggestive of sleep disordered breathing. Further on, clinical course of coronary artery disease seems to be influenced by nocturnal breathing disorders. Application of continuous positive airway pressure (CPAP) is effective in most of the patients and attenuates cardiodepressive hemodynamic effects of obstructive sleep apnea.

Sleep apnea in heart failure patients

Growing evidence suggests that there may be a strong pathophysiologic link between congestive heart failure (CHF) and nocturnal breathing disorders due to nocturnal oxygen desaturation, intrathoracic pressure swings and sympathetic activation. It seems that sleep apnea contributes to systolic and diastolic heart failure, reduced left and right ventricular function and arrhythmia (e.g. atrial fibrillation). Therefore treatment of sleep apnea might alleviate cardiac symptoms and improve cardiac function. Nevertheless, the exact role of long term treatment of sleep apnea in heart failure patients remains to be elucidated.

Reduction of both number and proliferative activity of human endothelial progenitor cells in obesity

OBJECTIVE

Circulating endothelial progenitor cells (EPCs), responsible for neoangiogenesis and vascular repair, negatively correlate with vascular dysfunction and atherosclerotic risk factors. Because obesity may have a crucial role in the development of endothelial dysfunction, this study evaluated the number and proliferative activity of circulating human EPCs in obese (body mass index (BMI)=48+/-9, n=45) compared with lean (23+/-2, n=45) volunteers.

METHODS

EPCs were quantified after isolation of peripheral blood mononuclear cells (PBMCs) using fluorescence-activated cell sorting analyses. In addition, plated PBMCs developed colony-forming units (CFUs) from which 'outgrowth' endothelial cells (OECs) sprouted and differentiated into mature endothelial cells. Growth rates were monitored by periodical microscopic evaluation. Cell-cycle protein expression was determined by western blot analyses.

RESULTS

BMI negatively correlated (P<0.01) with the number of CD34(+)/CD133(+)/KDR(+) (r=-0.442), CD34(+)/KDR(+) (r=-0.500) and CD133(+)/KDR(+) (r=-0.282) EPCs. Insulin, leptin, HbA(1c), high-sensitivity C-reactive protein and hypertension, as well as diminished high-density lipoprotein and apolipoprotein A1, were not only associated with obesity but also with significantly reduced EPC levels. Applying selective culture conditions, EPC-CFUs differentiated into OECs that proliferated more slowly when derived from obese compared with lean subjects (obese: 19.9+/-2.2% vs lean: 30.9+/-3.2% grown area per week, P<0.01). The reduced proliferation was reflected by decreased (P<0.05, n=24 for each group) expression of cell-cycle-promoting cyclins and E2F-1, by hypophosphorylation of retinoblastoma protein and by increased (P<0.05, n=24 for each group) expression of the cell-cycle inhibitor p21(WAF-1/Cip1).

CONCLUSIONS

Reduced numbers of EPCs along with their premature senescence, as shown in this study, could function as early contributors to the development and progression of vascular dysfunction in obesity.

Adenosine diphosphate-inducible platelet reactivity shows a pronounced age dependency in the initial phase of antiplatelet therapy with clopidogrel

BACKGROUND

Until recently, there were hardly any data on the antiplatelet effect of clopidogrel in advanced age. Like other metabolic processes, the conversion of clopidogrel to its active metabolite may be impaired in older patients, leading to high on-treatment residual ADP-inducible platelet reactivity.

OBJECTIVE

To investigate the age dependency of clopidogrel-mediated platelet inhibition.

PATIENTS AND METHODS

This was a prospective observational study. We determined adenosine 5'-diphosphate (ADP)-inducible platelet reactivity using light transmission aggregometry (LTA) and the VerifyNow P2Y12 assay in 191 patients on dual antiplatelet therapy after angioplasty and stenting for cardiovascular disease.

RESULTS

ADP-inducible platelet reactivity increased linearly with age after adjustment for cardiovascular risk factors, type of intervention, medication, C-reactive protein (CRP) and renal function [using LTA 0.36% of maximal aggregation per year, 95% CI 0.08-0.64%, P = 0.013; using the VerifyNow P2Y12 assay 3.2 P2Y12 reaction units (PRU) per year, 95% CI 1.98-4.41 PRU, P < 0.001]. ADP-inducible platelet reactivity was significantly higher in patients aged 75 years or older compared with younger patients (P = 0.003 for LTA and P < 0.001 for the VerifyNow P2Y12 assay). Further, high on-treatment residual ADP-inducible platelet reactivity was significantly more common among patients aged 75 years or older (P = 0.02 for LTA and P < 0.001 for the VerifyNow P2Y12 assay).

CONCLUSION

ADP-inducible platelet reactivity shows a pronounced age dependency in the initial phase of antiplatelet therapy with clopidogrel. The clinical implications of these findings need to be addressed in future trials.

[Pathophysiology of the right ventricle in lung diseases]

The thin-walled right heart is characterized by a low mass-volume-relation. Right ventricular function is influenced basically by loading conditions (afterload and preload), myocardial perfusion, contractility and heart rate. Afterload is determined by intrathoracal and pulmonary vascular pressure/resistance. Morphologic adaptions of the right ventricle affect right ventricular function in cor pulmonale. So the normal, not hypertrophied right ventricle is extremely sensitive to increasing pulmonary artery pressure. Otherwise, minor reductions in afterload lead to a substantial decrease of right ventricular wall stress, myocardial oxygen demand and likely the risk of arrhythmia. Therefore clinical consequences and complications of pulmonary hypertension are substantially dependent on right ventricular dynamics.

Potential regulation of gene expression in photosynthetic cells by redox and energy state: approaches towards better understanding

BACKGROUND

Photosynthetic electron transport is performed by a chain of redox components that are electrochemically connected in series. Its efficiency depends on the balanced action of the photosystems and on the interaction with the dark reaction. Plants are sessile and cannot escape from environmental conditions such as fluctuating illumination, limitation of CO(2) fixation by low temperatures, salinity, or low nutrient or water availability, which disturb the homeostasis of the photosynthetic process. Photosynthetic organisms, therefore, have developed various molecular acclimation mechanisms that maintain or restore photosynthetic efficiency under adverse conditions and counteract abiotic stresses. Recent studies indicate that redox signals from photosynthetic electron transport and reactive oxygen species (ROS) or ROS-scavenging molecules play a central role in the regulation of acclimation and stress responses.

SCOPE

The underlying signalling network of photosynthetic redox control is largely unknown, but it is already apparent that gene regulation by redox signals is of major importance for plants. Signalling cascades controlling the expression of chloroplast and nuclear genes have been identified and dissection of the different pathways is advancing. Because of the direction of information flow, photosynthetic redox signals can be defined as a distinct class of retrograde signals in addition to signals from organellar gene expression or pigment biosynthesis. They represent a vital signal of mature chloroplasts that report their present functional state to the nucleus. Here we describe possible problems in the elucidation of redox signalling networks and discuss some aspects of plant cell biology that are important for developing suitable experimental approaches.

CONCLUSIONS

The photosynthetic function of chloroplasts represents an important sensor that integrates various abiotic changes in the environment into corresponding molecular signals, which, in turn, regulate cellular activities to counterbalance the environmental changes or stresses.

Obstructive sleep apnea in heart failure patients: evidence for persistent conduction disturbances or sinus node dysfunction

Bradycardia is a common finding in patients with obstructive sleep apnea and might be pronounced in heart failure patients. The aim of the present study was to determine the relationship between nocturnal hypoxemia, apnea-hypopnea index, and electrophysiological parameters of sinus node and atrioventricular conduction properties. Electrophysiological studies were performed in 12 patients with heart failure. Polygraphic studies were done in all of the patients. Patients with an AHI >10/h were classified as sleep apnea patients. Mild sleep apnea was diagnosed in 50% of the patients (AHI 17.8 +/- 4.4 vs. 5.1 +/- 3.6/h). There were no differences with respect to the resting heart rate, PQ interval, or QRS duration between the two groups. Sinus node recovery time was normal in all of the patients (993 +/-291 vs. 1099 +/-62 ms, P=0.45). There was no abnormal atrioventricular conduction. Nevertheless, sleep apnea patients showed decreased atrioventricular conduction time (AH) intervals (134 +/- 42 vs. 102 +/- 25 ms, P=0.1) and infranodal conduction time (HV) intervals (59 +/- 9 vs. 43 +/- 7 ms, P=0.01). We conclude that mild sleep apnea was not associated with abnormal findings in sinus node function or AV conduction properties in patients with heart failure. Decreased AH/HV intervals might be a consequence of apnea associated sympathetic activation.

Cardiac chemoreflex sensitivity in critically ill patients

Chemoreflexes are important mechanisms for regulating ventilatory and cardiovascular function. The aim of this study was to determine the meaning of autonomic dysfunction for the pathophysiology and outcome in critical ill patients. For the determination of the chemoreflex sensitivity (ChRS), the ratio of the RR interval shift and the shift of oxygen partial pressure during a 5-min inhalation of oxygen with a nose mask was formed. Pathological chemoreflex sensitivity was predefined as a ChRS below 3.0 ms/mmHg. Out of the 27 critical ill patients included into the study, 17 had a sepsis and 10 a cardiogenic shock. In these patients, chemoreflex sensitivity was significantly reduced compared with a control group (sepsis: 2.1 +/- 1.68, cardiogenic shock: 0.4 +/- 0.27, controls: 5.0 +/- 2.8 ms/mmHg; P<0.05 vs. sepsis or cardiogenic shock). There was a significant negative correlation (r=-0.6; P<0.01) between the chemoreflex sensitivity and the severity of illness described by the SOFA-score. We conclude that cardiac reflex mechanisms are changed toward increased sympathetic activity reflected by reduced chemoreflex sensitivity in critical ill patients. Moreover, there is a close negative correlation between the ChRS and the SOFA-score.

A novel insulin formulation with a more rapid onset of action

AIMS/HYPOTHESIS

This study evaluates the pharmacodynamic and pharmacokinetic properties of the novel ultra-fast insulin product VIAject, a formulation of human soluble insulin and generally recognised as safe ingredients designed to increase the rate of absorption.

METHODS

We performed five euglycaemic glucose clamps (Biostator; target blood glucose 5 mmol/l) in ten healthy volunteers. Using a crossover design with a fixed treatment order, 12 IU human soluble insulin, 12 U insulin lispro and 12 IU ultra-fast insulin were injected s.c. in the abdominal region on three study days. On the other two study days, 6 and 3 IU ultra-fast insulin were injected.

RESULTS

Subcutaneous injection of 12 IU ultra-fast insulin resulted in a time-action profile characterised by an even more rapid onset of action and maximal metabolic activity than insulin lispro: time to early half-maximal activity was 33 +/- 17 min (mean +/- SD) vs insulin lispro 51 +/- 13 min vs human soluble insulin 66 +/- 15 min (p < 0.05 ultra-fast insulin<insulin lispro<human soluble insulin); time to maximal activity was 136 +/- 56 min vs insulin lispro 152 +/- 30 min vs human soluble insulin 193 +/- 57 min (p < 0.05 ultra-fast insulin and insulin lispro<human soluble insulin). The metabolic activity in the first 2 h after injection was higher with ultra-fast insulin and insulin lispro than with human soluble insulin (AUC glucose infusion rate [GIR] 0-120 min: 915 +/- 301 and 781 +/- 174 vs 580 +/- 164 mg/kg; p < 0.05). A clear dose-response relationship was observed with the three doses of ultra-fast insulin: AUCGIR 0-120 min 12 IU 915 +/- 301 vs 6 IU 718 +/- 255 vs 3 IU 524 +/- 262 mg/kg (p < 0.05). The pharmacokinetic data confirmed the pharmacodynamic results.

CONCLUSIONS/INTERPRETATION

This study shows that the onset of action of VIAject is faster than that of human soluble insulin and insulin lispro.

[Malignant mixed Müllerian tumor of the urinary bladder]

True mixed epithelial-mesenchymal tumors of the urinary bladder are exceedingly rare, and only two vesical adenosarcomas have been reported to date. These tumors originated from bladder endometriosis, and malignant transformation of endometriosis has been described, with endometrioid and clear-cell carcinomas being the most common malignancies. We report an unusual case of a malignant mixed Müllerian tumor with heterologous rhabdomyoblastic differentiation, which originated in the urinary bladder of a postmenopausal woman. To the best of our knowledge, such a neoplasm has not yet been reported in the literature.

Long-term non-surgical therapy of severe persistent congenital hyperinsulinism with glucagon

BACKGROUND

Congenital hyperinsulinism (CHI) is characterized by severe hypoglycemia caused by dysregulated insulin secretion. The long-term outcome is dependent on prevention of hypoglycemic episodes to avoid the high risk of permanent brain damage. Severe cases are usually resistant to diazoxide or nifedipine. In addition, somatostatin analogues are ineffective in a subgroup of patients to achieve stable euglycemia. In these infants the only remaining long-term option has been subtotal pancreatectomy with high risk of diabetes mellitus. Intravenous infusions of glucagon are used as immediate treatment to stabilize euglycemia in affected newborns. The rationale of this treatment comes from the observation of an increased glycogen content of the liver when glycogenolysis is inhibited by insulin.

OBJECTIVE

To review the efficacy and safety of long-term subcutaneous glucagon infusion as a potential therapeutic option for blood glucose stabilization in infants with severe CHI without the need of additional intravenous glucose or immediate surgical intervention.

METHOD

Retrospective review of 9 children with CHI who received continuous subcutaneous infusion of glucagon for weeks or months. Glucagon was added to octreotide to replace octreotide-induced suppression of endogenous glucagon secretion, thereby liberating glucose by stimulation of hepatic glycogenolysis. In 3 cases, a stabilized formulation of glucagon was used to prevent glucagon crystallization that frequently occurs in smaller volumes.

RESULTS

Introduction of glucagon allowed the reduction or discontinuation of central glucose infusion in all children studied. In 2 patients, glucagon was introduced due to recurrent hypoglycemia despite subtotal pancreatectomy. Six out of 9 children were discharged home on this treatment, which their parents were able to continue without further symptomatic hypoglycemia, convulsions or unconsciousness. In 3 children, subcutaneous glucagon was continuously administered for 1-4 years leading to stable euglycemia. However, 2 children with diffuse type still required subtotal pancreatectomy. As a possible side effect, 2 children developed erythema necrolyticum, which resolved after discontinuation of the glucagon infusion. This has been described before in glucagonoma.

CONCLUSION

In this retrospective series, combination therapy of low-dose octreotide and subcutaneous glucagon infusion has been effective in preventing hypoglycemic episodes in severe CHI. We propose this may serve as a therapeutic option in place of high rates of glucose infusion through a central venous catheter and as an alternative to subtotal pancreatectomy in diffuse type of CHI.

Immunohistochemical expression patterns of AP2alpha and AP2gamma in the developing fetal human breast

AIMS

AP2alpha (TFAP2A) and AP2gamma (TFAP2G) transcription factors have been implicated in the control of proliferation, differentiation and apoptosis of normal breast epithelium and in breast cancer. The aim of this study was to provide a comprehensive analysis of the expression patterns of TFAP2A and TFAP2G in the developing fetal breast anlage with other relevant markers.

METHODS AND RESULTS

Sixty fetal and one infant human breast specimens from 14 weeks of gestational age to 5 months old were examined. The primary breast outgrowth/nipple showed TFAP2A expression by the basal cells (week 14), followed later by cytokeratin (CK) 5 co-expression (week 17). Sprouting of the secondary outgrowths was characterized by HER-2+ invading cells. Preliminary ductal buds were lined by TFAP2G/HER-1-expressing myoepithelial precursors (week 19). Maturation of TFAP2A/CK18+ epithelia and TFAP2G/smooth muscle actin-positive myoepithelia proceeded in a distal-to-proximal manner beginning in the terminal end buds (week 22). CK5+ progenitor cells and CK5/TFAP2A or CK5/TFAP2G co-expressing intermediary glandular or myoepithelial cells were found in the terminal end buds of neonatal fetal breast tissue.

CONCLUSIONS

AP2 transcription factors may play decisive pacemaker roles in initiating and coordinating budding and branching processes during formation of the fetal breast anlage, possibly via modulation of an epidermal growth factor receptor.

Diagnostics in pulmonary hypertension

Pulmonary hypertension is a serious disease with a poor prognosis. Pulmonary hypertension is defined by a mean pulmonary arterial pressure over 25 mm Hg at rest or over 30 mm Hg during activity. According to the recent WHO classification from 2003 pulmonary hypertension can be categorized as pulmonary arterial hypertension, pulmonary venous hypertension, hypoxic pulmonary hypertension, chronic thromboembolic pulmonary hypertension and pulmonary hypertension from other causes. Pulmonary arterial hypertension is characterized histopathologically by vasoconstriction, vascular proliferation, in situ thrombosis, and remodeling of all 3 levels of the vascular walls. These pathologic changes result in progressive increases in the mean pulmonary artery pressure and pulmonary vascular resistance, which, if untreated leads to right-ventricular failure and death. Early in the disease process, the signs and symptoms of PAH are often nonspecific, making diagnosis challenging. Patients often present with progressively worsening dyspnea and fatigue. Patients with severe pulmonary arterial hypertension die of right heart failure. The diagnostic procedures include clinical history and physical examination, a standard chest radiography, electrocardiography, transthoracic Doppler echocardiography, pulmonary function tests, arterial blood gas analysis, ventilation and perfusion lung scan, high-resolution computed tomography of the lungs, contrast-enhanced spiral computed tomography of the lungs and pulmonary angiography, blood tests and immunology, abdominal ultrasound scan, exercise capacity assessment, and hemodynamic evaluation. Invasive and non-invasive markers of disease severity, either biomarkers or physiological parameter and tests that can be widely applied, have been proposed to reliably monitor the clinical course. Pulmonary biopsy is rarely indicated. Transthoracic echocardiography is a key screening tool in the diagnostic algorithm. Because transthoracic echocardiography is an inexpensive, easy, and reproducible method, it is the most commonly used noninvasive diagnostic tool to determine pulmonary arterial pressure. But it not only provides an estimate of pulmonary pressure at rest and during exercise, but it may also help to exclude any secondary causes of pulmonary hypertension, predict the prognosis, monitor the efficacy of specific therapeutic interventions, and detect the preclinical stage of the disease. In addition, the measurement of serum markers, such as brain natriuretic peptide (BNP), are diagnostically useful and of prognostic significance. Once the diagnosis and etiology of pulmonary hypertension have been established, several parameters can predict outcome in these patients: functional class, right ventricular function, pulmonary hemodynamics, and certain laboratory parameters. Also, exercise parameters such as walking distance, peak oxygen uptake or peak systolic blood pressure can reliable predict prognosis in these patients.

Signal-averaged P-wave ECG as a marker of atrial electrical instability in patients with right ventricular dysfunction

Severe pulmonary hypertension (PAH) leads to right ventricular dysfunction and is associated with different atrial arrhythmias. In PAH patients, the echocardiographic Tei-index is used for monitoring right heart function. The P-wave signal-averaged ECG (SA-ECG) has been shown to have a potential role in identifying patients at risk of developing paroxysmal atrial fibrillation and those likely to change from paroxysmal to chronic atrial fibrillation. The aim of the present study was to define the correlation of the Tei-Index with parameters of P-wave triggered and bidirectional P-wave SA-ECG. A total of 18 patients (14 men, 4 women) with normal sinus rhythm and a mean age of 67+/-10 years (BMI 27.6+/-5.1 kg/m2) were included into the study. Right ventricular (RV) Tei-index was calculated from the sum of isovolumetric contraction time and relaxation time divided by ejection time. Furthermore, P-wave triggered P-wave signal averaged ECG was performed from an X, Y, and Z lead system. The results show that there was a statistically significant correlation between Tei-index and filtered P-wave duration (r=0.53; P=0.023). Teiindex did not correlate with the root mean square voltage of the last 20 ms of the P wave (r=-0.16; P=0.52). In conclusion, a correlation of RV Tei index with P-wave duration indicates that this echocardiographic measurement is not only a marker of right heart function, but also an indicator of electrical instability that could be useful to detect patients at risk for atrial arrhythmias.

Factors influencing spontaneous mobilization of CD34+ and CD133+ progenitor cells after myocardial infarction

BACKGROUND

Bone marrow-derived circulating progenitor cells (BM-CPCs) are mobilized into adult peripheral blood (PB) during acute myocardial infarction (AMI) and may contribute to the regeneration of infarcted myocardium. The purpose of the present study is to determine whether mobilization of BM-CPCs into PB depends on cardiovascular risk factors (CVRFs), age of patients, infarct associated inflammatory markers, and left ventricular function after AMI.

MATERIALS AND METHODS

Peripheral blood concentrations of CD34/45(+) and CD133/45(+) BM-CPCs were measured by flow cytometry in 44 patients after AMI and in 16 subjects with atypical chest pain acting as controls.

RESULTS

Mobilization of CD34/45(+) and CD133/45(+) BM-CPCs on day 1 after AMI showed significant negative correlation with age, the number of CVRFs, infarct size, creatine phosphokinase peak in bivariate as well as in multivariate analyses. We additionally found a positive correlation of CD34/45(+) and CD133/45(+) BM-CPCs mobilization on day 1 after AMI with global ejection fraction (EF) in bivariate analysis but could not confirm this in multivariate analysis. Elevated of C-reactive protein (CRP) and leukocyte levels on day 1 after AMI were significantly associated with decreased concentrations of CD34/45(+) BM-CPCs. The concentrations of CD34/45(+) and CD133/45(+) BM-CPCs significantly increased in AMI patients, with the peak on day 7 as compared to the control group.

CONCLUSIONS

The mobilization of CD34/45(+) and CD133/45(+) BM-CPCs into the PB depends on many factors, i.e. the number of CVRFs, age, infarct size and inflammatory markers of patients. Most importantly, the severity of the circulatory dysfunction and the amount of necrotic myocardial tissue are the main determinants. Moreover, this spontaneous mobilization of BM-CPCs may serve as a very important surrogate for infarct size as well as for global EF and it may determine the regenerative potency after AMI.

Effects of continuous positive airway pressure on exercise capacity in chronic heart failure patients without sleep apnea

Continuous positive airway pressure (CPAP) is an effective treatment for obstructive sleep apnea. It is known, that there are beneficial effects on cardiac function, which might be explained by suppression of apnea and specific hemodynamic effects of CPAP. Therefore, CPAP might act as an adjunct therapy in heart failure, even in the absence of sleep apnea. In the present study, 11 patients with congestive heart failure (EF=23.1+/-6.9%) without sleep apnea (AHI 3.0+/-1.2/h) were treated with nocturnal CPAP. Cardiopulmonary exercise testing was performed at baseline and after 8.6 +/-1.3 months. All patients underwent heart catheterization and myocardial biopsy to exclude myocarditis at baseline. Five (46%) of the 11 patients did not complete the study because of poor compliance and irregular use of the CPAP device. Six (54%) of the patients used CPAP regularly (>6 h/night) and completed the study. Cardiopulmonary exercise testing showed an improvement of work load (96+/-36 Watt vs. 112+/-34 Watt; P=0.025) and VO2 peak (1227+/-443 ml vs. 1525+/-470 ml; P=0.01). Oxygen-pulse was increased, although that did not reach significance (11.2+/-4.8 ml/beat vs. 12.6+/-3.9 ml/beat). In conclusion, CPAP might have beneficial effects on exercise capacity in patients with congestive heart failure even in the absence of sleep apnea. Nevertheless, poor compliance seems to be a limiting factor.

Elevated levels of interleukin-1beta-converting enzyme and caspase-cleaved cytokeratin-18 in acute myocardial infarction

BACKGROUND

Systemic inflammation and apoptosis-specific immune activation play a major role in acute coronary syndromes (ACS) including acute myocardial infarction (AMI). The role of systemic and coronary obtained inflammatory plasma protein interleukin-1beta precursor (IL-1betap), IL-1beta-converting enzyme (ICE) and the apoptosis-specific caspase-cleaved cytokeratin-18 (ccCK-18) are not known in ACS.

MATERIALS AND METHODS

Plasma samples were obtained from stable angina (SA, n = 34), unstable angina (UA, n = 37) and patients with AMI (n = 39). Coronary blood was acquired by means of thrombectomy devices (X-sizer) in AMI patients. IL-1betap, ICE and ccCK-18 were determined by enzyme-linked immunosorbent assay (ELISA). Group comparisons were evaluated by parametric Tukey test. Multivariate logistic regression analysis was performed to determine predictive values of IL-1betap, ICE and ccCK-18 as compared to creatine kinase (CK) and troponin T (TnT) in order to relate these markers with the occurrence of myocardial damage.

RESULTS

IL-1betap, ICE and ccCK-18 were identified to be significantly altered in the peripheral blood of patients suffering from AMI as compared to SA and UA. ROC curves were plotted and revealed that ccCK-18 is a novel sensitive marker for the detection of myocardial damage as compared to TnT or CK. (AUC ccCK-18 0.925, TnT AUC 0.62 and CK AUC 0.858.) Moreover, ICE and ccCK-18 were significantly increased at the site of coronary occlusion as compared to peripheral blood samples in AMI patients (both P < 0.001).

CONCLUSION

Our data suggest that ACS is related to increased concentration of systemic soluble ICE and ccCK-18. Moreover, soluble ccCK-18 was identified to be a superior marker as compared to TnT or CK, for detection of myocardial damage.

Kardiovaskuläre Endorganschäden des Hochdrucks

Arterial hypertension is the most frequent cause of pressure overload on the left ventricle. Longer lasting arterial hypertension leads to hypertension-specific organ manifestations summarized as "hypertensive heart disease". Hypertensive heart disease comprise the manifestation of stenosis in epicardial arteries, hypertensive microvascular disease, ischemic cardiomyopathy, left ventricular hypertrophy, endothelial dysfunction, increased sympathetic drive and degeneration of aortic valve. Diastolic dysfunction and reduced coronary flow reserve can be evaluated as early markers of hypertensive heart disease. These alterations lead to the major clinical manifestations of hypertensive heart disease that are symptoms of reduced coronary insufficiency with typical angina pectoris, but also of symptoms of heart failure (systolic and diastolic dysfunction) and arrhythmia. Different non-invasive and invasive procedures are available for screening and follow-up of patients with hypertensive heart disease. Primary therapeutic target is, apart from lowering blood pressure, to reverse cardiac manifestations of arterial hypertension using specific therapeutic algorithms.

Inflammatory Cytokines Interleukin-6 and Oncostatin M Induce Plasminogen Activator Inhibitor-1 in Human Adipose Tissue

Background— Adipose tissue is a prominent source of plasminogen activator inhibitor-1 (PAI-1), the primary physiological inhibitor of plasminogen activation. Increased PAI-1 expression acts as a cardiovascular risk factor, and plasma levels of PAI-1 strongly correlate with body mass index (BMI). Elevated serum levels of interleukin-6 (IL-6), an inflammatory cytokine and a member of the glycoprotein 130 (gp130) ligand family, are found in obese patients and might indicate low-grade systemic inflammation. Another gp130 ligand, oncostatin M (OSM), upregulates PAI-1 in cardiac myocytes, astrocytes, and endothelial cells. We used tissue explants and primary cultures of preadipocytes and adipocytes from human subcutaneous and visceral adipose tissue to investigate whether IL-6 and OSM affect PAI-1 expression in fat.

Methods and Results— Human subcutaneous and visceral adipose tissue responded to treatment with IL-6 and OSM with a significant increase in PAI-1 production. Human preadipocytes were isolated from subcutaneous and visceral adipose tissue. Adipocyte differentiation was induced by hormone supplementation. All cell types expressed receptors for IL-6 and OSM and produced up to 12-fold increased levels of PAI-1 protein and up to 9-fold increased levels of PAI-1 mRNA on stimulation with IL-6 and OSM. AG-490, a janus kinase/signal transducer and activator of transcription inhibitor, abolished the OSM-dependent PAI-1 induction almost completely.

Conclusions— We have for the first time established a link between the gp130 ligands, the proinflammatory mediators IL-6 and OSM, and the expression of PAI-1 in human adipose tissue. Thus, we speculate that IL-6 and OSM, by upregulating PAI-1 in adipose tissue, can contribute to the increased cardiovascular risk of obese patients.

[Functional dynamics of the right ventricle and pulmonary circulation in obstructive sleep apnea. Therapeutic consequences]

Obstructive sleep apnea (OSA) is common with an incidence of at least 500,000 patients in the German population. Typical symptoms are daytime sleepiness, headache in the morning, and snoring. Presumably obstructive sleep apnea via various mechanisms increases cardiovascular morbidity. Hypoxemia causes nocturnal hypertension in most of the patients. Nevertheless, about 20% of the patients develop daytime pulmonary hypertension and right heart dysfunction. Clinical and animal studies demonstrated right ventricular hypertrophy as a consequence of intermittent hypoxemia and pulmonary hypertension. Right ventricular hemodynamics differ essentially from left ventricular hemodynamics. Right ventricular function is substantially influenced by right ventricular afterload, which is mainly determined by pulmonary vascular resistance, and slightly influenced by preload. Application of continuous positive airway pressure (CPAP) via a nose mask normalizes nocturnal breathing disorders and reduces pre- and afterload, especially in patients with cardiomegaly. Therefore, CPAP generates positive effects on the myocardium.

Disseminated Microvascular Pulmonary Tumor Cell Embolism: A Rare Cause of Fulminant Pulmonary Hypertension

BACKGROUND

Disseminated pulmonary tumor embolization is a rare cause of pulmonary hypertension and is often diagnosed only after the patient has died.

CASE REPORT

We report on a 41-year-old male who was admitted because of severe dyspnea and tachycardia. Contrast enhanced spiral computed tomography did neither establish pulmonary thromboembolism nor pulmonary metastasis. Right heart catheterization revealed severe pulmonary hypertension (pulmonary vascular resistance (PVR) 678 dyn x sec x cm(-5)). PVR did not respond to therapy with intravenous nitrate or inhaled iloprost in this critically ill patient. 2 days after admission, the patient died because of refractory right heart failure. Autopsy revealed microscopic pulmonary tumor embolism due to a metastasizing adenocarcinoma of the pancreas.

CONCLUSION

Disseminated tumor cell embolism should be considered as a rare differential diagnosis in patients with refractory pulmonary hypertension.

[Determinants of paroxysmal atrial fibrillation in patients with arterial hypertension]

INTRODUCTION

Atrial fibrillation represents an important arrhythmia, in particular in patients with arterial hypertension. Hitherto, the connection between paroxysmal atrial fibrillation, left atrial size and left ventricular muscle mass has not been investigated sufficiently. In the present study, determinants of paroxysmal atrial fibrillation in patients with arterial hypertension were evaluated.

METHODS

104 consecutive patients were enrolled into this study. All of them suffered from arterial hypertension for more than one year. Persistent or permanent atrial fibrillation was not documented. In all of these patients, clinical, echocardiographic and rhythmologic variables were evaluated.

RESULTS

In 10.3% of the patients, paroxysmal atrial fibrillation was found. These patients showed a significantly larger left atrium (43.3 +/- 6.7 vs 37.5 +/- 4.9 mm, p < 0.001), a significantly higher muscle mass of the left ventricle (152.38 +/- 43.57 vs 134.41 +/- 27.19 g/m2, p < 0.01) and significantly more frequent a mild mitral regurgitation (38.1 vs 28.6%, p < 0.01). The multivariate regression analysis revealed as independent factors for paroxysmal atrial fibrillation the size of the left atrium and the presence of mild mitral regurgitation. Independent factors for an enlarged left atrium were mitral insufficiency and left ventricular muscle mass.

CONCLUSION

This study shows that paroxysmal atrial fibrillation in aterial hypertension is based on the left atrial size, and left atrial size on left ventricular muscle mass. Therefore, these results should lead to a causal therapy for treatment of paroxysmal atrial fibrillation in these patients.

[Catheter embolisation into the pulmonary artery. Interventional therapy of a rare form of pulmonary embolism]

Embolisation of a foreign body is a rare cause of pulmonary embolism. We report on a 67 year old female suffering from colorectal cancer. To perform adjuvant chemotherapy a port system was inserted into the right subclavian vein. Routine chest radiography revealed a rupture of the venous port-system, which was embolised into the right pulmonary artery without clinical symptoms. The foreign body was removed without complications using a nitinol goose neck snare via a transfemoral approach and retrieved percutaneously. The reported procedure is safe, decreases operation and hospitalisation time and should therefore be performed in preference to surgical management whenever possible.

Technosphere/Insulin--proof of concept study with a new insulin formulation for pulmonary delivery

Summary.Technosphere/Insulin (TI) is a formulation of regular human insulin and Technosphere, a new drug delivery system for pulmonary administration. The formulation is designed for efficient transport of insulin across the intact respiratory epithelium into the systemic circulation. We have investigated the pharmacodynamic and pharmacokinetic properties of Technosphere/Insulin in five healthy, non-smoking volunteers. In an open, randomized, three-way crossover study, subjects received 5 IU regular human insulin (HI) intravenously, 10 IU HI subcutaneously; and 100 IU TI via inhalation using a small commercially available asthma inhaler. The time action profiles of all three insulin formulations were assessed by the euglycemic glucose clamp technique on three different study days. Glucose infusion rates were monitored from 2 h before until 6 h after insulin administration. Other study measures were serum insulin, serum C-peptide concentrations, and safety parameters. The inhalation of TI was well tolerated. The time to peak action was significantly shorter with both i.v. injection and inhalation, as compared to s.c. (14 +/- 6 min and 39 +/- 36 min vs. 163 +/- 25 min; p < 0.0002 and p < 0.007 (mean +/- SD)). The metabolic effect during the first 3 h after insulin administration was higher with inhaled TI than with HI s.c. (AUC0-180 for glucose infusion rate: 1.94 +/- 0.77 mg/kg * min vs. 1.15 +/- 0.50 mg/kg * min; p < 0.04). Relative and absolute bioavailability for the first 3 h were 26 +/- 12% and 15 +/- 5% respectively (6 h: 16 +/- 8 and 16 +/- 6%). We conclude that inhalation of TI leads to a rapid onset of metabolic action resembling the effect observed with i.v. administration of regular HI. Despite the use of a common asthma inhaler, bioavailability over the three hour prandial period was substantially greater than with other reported pulmonary systems. Therefore, inhalation of Technosphere/Insulin may become a suitable and attractive alternative for prandial insulin delivery, especially for patients with type 2 diabetes mellitus.

Precious things come in little packages

The 110-amino acid multidrug transporter from E. coli, EmrE, is a member of the family of MiniTexan or Smr drug transporters. EmrE can transport acriflavine, ethidium bromide, tetraphenylphosphonium (TPP+), benzalkonium and several other drugs with relatively high affinities. EmrE is an H+/drug antiporter, utilizing the proton electrochemical gradient generated across the bacterial cytoplasmic membrane by exchanging two protons with one substrate molecule. The EmrE multidrug transporter is unique in its small size and hydrophobic nature. Hydropathic analysis of the EmrE sequence predicts four alpha-helical transmembrane segments. This model is experimentally supported by FTIR studies that confirm the high alpha-helicity of the protein and by high-resolution heteronuclear NMR analysis of the protein structure. The TMS of EmrE are tightly packed in the membrane without any continuous aqueous domain, as was shown by Cysteine scanning experiments. These results suggest the existence of a hydrophobic pathway through which the substrates are translocated. EmrE is functional as a homo-oligomer as suggested by several lines of evidence, including co-reconstitution experiments of wild-type protein with inactive mutants in which negative dominance has been observed. EmrE has only one membrane embedded charged residue, Glu-14, that is conserved in more than fifty homologous proteins and it is a simple model system to study the role of carboxylic residues in ion-coupled transporters. We have used mutagenesis and chemical modification to show that Glu-14 is part of the substrate-binding site. Its role in proton binding and translocation was shown by a study of the effect of pH on ligand binding, uptake, efflux and exchange reactions. We conclude that Glu-14 is an essential part of a binding site, common to substrates and protons. The occupancy of this site is mutually exclusive and provides the basis of the simplest coupling of two fluxes. Because of some of its properties and its size, EmrE provides a unique system to understand mechanisms of substrate recognition and translocation.

Cholesterol biosynthesis regulation and protein changes in rat liver following treatment with fluvastatin

The enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase is a key regulator in cholesterol biosynthesis and HMG CoA reductase inhibitors (statins) have become a widely prescribed family of lipid lowering agents. Cholesterol synthesis occurs predominantly in liver which is the target organ of statins. We studied the effects of fluvastatin (Lescol), a member of the statin family, on hepatic protein regulation. Male F344 rats treated with 0.8 mg/kg per day fluvastatin or 24 mg/kg per day fluvastatin for 7 days showed treatment-related changes in 58 liver proteins (P<0.005). Major effects were evident in the cholesterol biosynthesis pathway including the induction of enzymes upstream and downstream of the target enzyme HMG CoA reductase. Treatment also triggered alterations in key enzymes of carbohydrate metabolism and was associated with changes in a heterogeneous set of cellular stress proteins involved in cytoskeletal structure, calcium homeostasis and protease activity. The latter set of protein alterations indicates that hepatotoxicity is associated with high-dose treatment. Based on the results it is suggested that HMG-CoA synthase and isopentenyl-diphosphate delta-isomerase may be explored as alternative drug targets and that the induction levels of these enzymes may serve as a measure of potency of individual statin drugs. It is proposed that efficacy and cellular stress markers discovered in this study may be used in a high throughput screen (HTS) assay format to compare efficiently and accurately the therapeutic windows of different members of the statin family.

Pharmaceutical proteomics

Genomics and proteomics are today well established in drug discovery and, in combination with combinatorial chemistry and high-throughput screening, are helping to bring forward an unprecedented number of potential lead compounds. To avoid the generation of bottlenecks downstream in drug development, increasing pressure is arising to integrate these technologies into the development environment. Proteomics has demonstrated proof-of-concept in toxicology as shown by a number of successful applications in mechanistic toxicology and lead selection. The "technology wave" is now starting to impact the clinical phase of drug development. Expected benefits are optimized clinical trials based on the availability of biologically relevant markers of drug efficacy and safety.

Proteomics to display lovastatin-induced protein and pathway regulation in rat liver

Lovastatin is a lipid lowering agent that acts by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, a key regulatory enzyme in cholesterol biosynthesis. In this study the pattern of gene network regulation induced in hepatic proteins as a response to lovastatin treatment was analyzed by proteomics. In livers of male F344 rats treated with 1.6 mg/kg/day lovastatin or 150 mg/kg/day lovastatin for seven days, 36 proteins were found to be significantly altered (p<0.001) in relation to treatment. The changed proteins were classified according to their cellular function and participation in biochemical pathways. The following observations were made: (i) inhibition of HMG-CoA reductase provoked a regulatory response in the cholesterol synthesis pathway including the induction of cytosolic HMG-CoA synthase and of isopentenyl-diphosphate delta-isomerase, (ii) manipulation of the lipid metabolism triggered alterations in key enzymes of the carbohydrate metabolism, and (iii) lovastatin treatment was associated with signs of toxicity as reflected by changes in a heterogeneous set of cellular stress proteins involved in functions such as cytoskeletal structure, calcium homeostasis, protease inhibition, cell signaling or apoptosis. These results present new insights into liver gene network regulations induced by lovastatin and illustrate a yet unexplored application of proteomics to discover new targets by analysis of existing drugs and the pathways that they regulate.