Autonomic dysfunction in the ICU patient

The sympathetic-parasympathetic balance may be altered in critically ill patients. Assessment of autonomic function provides information concerning prognosis, pathogenesis, and treatment strategies in ICU-relevant disorders. Proven tools are heart rate variability, baroreflex sensitivity, and, with limitations, cardiac chemoreflex sensitivity. New nonlinear methods are being evaluated that may predict risk more precisely in critically ill patients. This article summarizes application of these tools in the ICU. In addition, a model is introduced for investigating the impaired autonomic function in multiple organ dysfunction syndrome and sepsis, integrating extrinsic mechanisms and factors that are intrinsic to the cardiac tissue. By this combined approach, the authors hope to gain insight into the pathogenesis of multiple organ dysfunction syndrome. New pathophysiologic concepts are needed for the development of treatment strategies for this life-threatening disease.

Identification and characterization of heat shock protein 27 protein species in human myocardial two-dimensional electrophoresis patterns

Immunostaining of heat shock protein 27 (Hsp27) protein species on two-dimensional electrophoresis (2-DE) gels with enhanced sensitivity yields 59 spots reacting with anti-Hsp27 antibodies. Recombinant Hsp27 exists in 2-DE as two major protein species which comigrate in the human myocardial pattern with Hsp27 spots C754 and D899 as defined in the heart high-performance 2-DE database (http://www.mdc-berlin.de/emu/heart/). Preparative electrophoresis of human myocardial proteins and analysis of the enriched mass range 20-30 kDa by 2-DE revealed eight protein spots (C438, C582, C658, C697, C754, C595, C750) from the human myocardial database and a new spot not previously detected on silver-stained gels. These spots were identified as Hsp27 protein species by enzymatic in-gel-digestion and analysis by matrix assisted laser desorption-ionization (MALDI) peptide mass fingerprinting and, in part, MALDI-post source decay sequencing of single fragments. Possible post-translational modifications were investigated: immunostaining tests with anti-phospho-serine/-threonine/-tyrosine antibodies, although positive for other myocardial proteins, were negative for presumed Hsp27 protein species; likewise, periodate-glycostaining assays and biotinylation screening did not detect modifications in the investigated Hsp27 protein species.

Endotoxin and tumor necrosis factor alpha exert a similar proinflammatory effect in neonatal rat cardiomyocytes, but have different cardiodepressant profiles

Bolus application of endotoxin to healthy volunteers results in reversible hemodynamic alterations, such as observed in septic cardiomyopathy. Currently, endotoxin-induced cardiodepression is mainly attributed to the endotoxin-induced release of proinflammatory cytokines into the circulation, particularly of tumor necrosis factor alpha and interleukin-1, the serum levels of these cytokines being enhanced in sepsis and septic shock, and also in various heart diseases. In this study, we report a proinflammatory effect of endotoxin (1-10 micrograms/ml, 24-h incubation period) on neonatal rat cardiomyocytes in serum-free culture, evidenced by induction of inducible nitric oxide synthase, enhanced release of nitrite (protein synthesis-dependent) and interleukin-6 into the supernatant, as well as an increase in cell-associated interleukin-1 and a specific cardiodepressant profile: endotoxin disrupts beta-adrenoceptor-mediated increase in pulsation amplitude, but alpha-adrenoceptor-induced increase in pulsation amplitude and arrhythmias are not suppressed. In the presence of dexamethasone (0.1 microM), the endotoxin-mediated blockade of beta-adrenergic responsiveness, as well as induction of inducible nitric oxide synthase, enhanced nitrite release and interleukin-1/-6-production are inhibited. In contrast, tumor necrosis factor alpha at a low concentration (10 U/ml) depresses alpha- and beta-adrenergic responsiveness in the presence of dexamethasone in a nitric oxide-independent manner. These data suggest a stimulatory effect of endotoxin on the cardiomyocyte and a specific proinflammatory and nitric oxide-dependent cardiodepressant profile of endotoxin.

High-performance human myocardial two-dimensional electrophoresis database: edition 1996

The master gel of the human myocardial two-dimensional electrophoresis (2-DE) gel database contains about 3300 protein spots characterized in terms of isoelectric point (pI) and molecular mass. A high-performance technique was applied, using large gels (23 x 30 cm). Isoelectric focusing with anodic sample preparation and nonequilibrium running conditions (NEPHGE) was combined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in 15% acrylamide gels in the second dimension. The range of pI extends from pH 4.5 to 9.6. Seventy proteins were identified by combinations of amino acid analysis, N-terminal and internal sequencing, immunostaining, matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) peptide mass fingerprinting, post-source decay MALDI-MS and ladder sequencing by carboxypeptidase P. The identification of additional proteins, not found in the master gel, was achieved by immunoblotting. Unequivocal identification with high sensitivity and good yield was obtained by combining internal sequencing and MALDI-MS. In-gel digestion, the concentration and purification of peptides in a peptide collecting device, and the improved FRAGMOD program for peptide mass fingerprinting have added to the security and sensitivity of identification. The high-performance human myocardial 2-DE database was built up with proteins detected by the TOPSPOT program. Spots within six sections of the whole pattern are clickable. Protein description includes detailed information about identification, characterization, and links to the related SWISS-PROT, other 2-DE databases and Medline entries. The database is constructed in accordance with four of the rules for a federated database.

Tumor necrosis factor alpha (TNF alpha) is cardiodepressant in pathophysiologically relevant concentrations without inducing inducible nitric oxide-(NO)-synthase (iNOS) or triggering serious cytotoxicity

Cardiac hypertrophy and heart failure are frequently accompanied by elevated plasma levels of tumor necrosis factor alpha (TNF alpha), the pathogenetic relevance of this finding being a matter of debate. In human acute septic cardiomyopathy, on the other hand, the negative inotropic impact of TNF alpha on the heart is well documented and frequently ascribed to the induction of inducible nitric oxide (NO) synthase (iNOS) and an enhanced production of NO in the heart. Yet the present study presents evidence that in cardiomyocytes TNF alpha in non-toxic concentrations specifically depresses contractile performance independent of NO. In spontaneously beating neonatal rat cardiomyocytes, TNF alpha in a low, pathophysiologically relevant concentration (10 U/ml, 1-3 days) does not alter basal pulsation amplitude, but blocks alpha- and beta-adrenoceptor-stimulated increase in contractility and beating irregularity and impairs the impact of high extracellular calcium on contractile performance. However, this low TNF alpha-concentration does not suffice to induce iNOS - documented by reverse transcriptase polymerase chain reaction - or enhance nitrite concentrations in the cell culture supernatants as a measure of cellular NO production, neither in the presence nor absence of dexamethasone (0.1 micro M). Only in high concentration - the specific proinflammatory action being documented by an enhanced release of interleukin-6 from cardiomyocytes - TNF alpha (1000 U/mol; 6, 24 h) weakly induces the mRNA for iNOS, with a consecutive moderate rise in cellular nitrite production. TNF alpha-incubation (10-1000 U/ml) does not alter the morphological appearance of the cells displayed by phase contrast microscopy or evoke gross cytotoxicity.

Partial inhibition of protein synthesis by Pseudomonas exotoxin A deranges catecholamine sensitivity of cultured rat heart myocytes

To elucidate cellular mechanisms of myocardial depression in Pseudomonas sepsis the effects of sublethal concentrations of P. aeruginosa exotoxin A--a main virulence factor--were studied in cultured neonatal rat cardiomyocytes. It is known that this toxin exerts its pathogenic effect by inhibition of protein synthesis via ADP-ribosylation and thereby inactivation of elongation factor 2 (EF-2). Within 48 72 h, half maximal inhibition of protein synthesis occurs at 4-10 ng/ml. The toxin prevents the beta-adrenoceptor(AR)-mediated myosin heavy chain isozyme shift (V3/V1), while the T3-induced myosin shift is not suppressed. While beta 1-AR-downregulation by excess of norepinephrine (NE) is not affected, protein synthesis-dependent receptor upregulation in the recover period after removal of NE is completely suppressed by P. aeruginosa exotoxin A. Thus, a non-lethal, partial inhibition of global cellular protein synthesis by P. aeruginosa exotoxin A: (1) completely prevents beta 1-AR-mediated myosin isozyme shift and beta-AR upregulation: (2) sustains the cardiomyocytes in a catecholamine-refractory contractile state in the recovery period after catecholamine desensitization: (3) suggests cellular mechanisms by which P. aeruginosa exotoxin A might impair heart function in Pseudomonas sepsis: and (4) may help reveal the possible influence of endogenous inhibitors of EF-2.

Separation and identification of human heart proteins

Heart failure is not a uniform disease entity, but a syndrome with various causes, including hypertension, ischemia and congenital heart disease, cardiomyopathy, myocarditis and intoxication. During the recent years a number of molecular and cellular alterations have been identified in the diseased heart, but a direct causative link between these changes and functional impairment, medical responsiveness, progression of the disease and the patients' outcome remains to be established. After an accumulation of large amounts of DNA sequence data in genomic projects, scientists have now turned their attention to the central executors of all programs of life, the proteins. In complementation of the genomic initiatives, proteomics based approaches have lined up not only for large-scale identification of proteins and their post-translational modifications, but also to study the function of protein complexes, protein-protein interactions and regulatory and signalling cascades in the cellular network. In concert with genomic data functional proteomics will hold the key for a better understanding and therapeutical management of cardiovascular diseases in the future.

Improved outcome of APACHE II score-defined escalating systemic inflammatory response syndrome in patients post cardiac surgery in 1996 compared to 1988-1990: the ESSICS-study pilot project

OBJECTIVE

Cardiac surgery using extracorporeal circulation leads to the release of cytokines and subsequently to a systemic inflammatory response syndrome, which is thought to be a negative prognostic factor for patients' outcome. A stratification for the risk of an escalating systemic inflammatory response syndrome had been achieved in a monocenter study carried out in 1988-1990, using APACHE II scoring on the morning of the 1st postoperative day. We now re-evaluated this concept prospectively in three independent centers.

METHODS

The APACHE II based risk stratification was put to test in three independent heart surgery centers in the period from June to December 1996. Nine hundred and forty-five patients after elective cardiac surgery (excluding heart transplantation) with the assistance of the cardiopulmonary bypass were prospectively monitored.

RESULTS

We found an increase in mortality with higher APACHE II score values determined on the 1st postoperative day. The mortality rose to nearly 50% with an APACHE II score of > or = 28. Patients at high risk for the development of a systemic inflammatory response syndrome (APACHE II score > or = 24) significantly differed from patients at lower risk (APACHE II score < 19) in the duration of mechanical ventilation and extracorporeal circulation, age and New York Heart Association (NYHA) classification (P < 0.05).

CONCLUSION

The APACHE II score determined on the morning of the 1st postoperative day helps identifying the subgroup of patients with escalating systemic inflammatory response syndrome. Comparison with the data obtained in the years 1988-1990, suggests a better prognosis in the current trial for patients at high risk with a similar degree of escalating systemic inflammatory response syndrome.

Elucidating molecular mechanisms of septic cardiomyopathy--the cardiomyocyte model

In the multiple organ dysfunction syndrome of sepsis and septic shock the heart is one of the organs subject to failure. Many new insights into the mechanisms underlying septic cardiomyopathy were gained in the last years. Experimental work with neonatal and adult cardiomyocytes considerably contributed to this progress, facilitating the documentation of direct attenuation of the contractions of the heart muscle cell by toxins and mediators, as well as investigating the underlying cellular mechanisms. With this respect, contractile-depressant effects have been found in cardiomyocytes for many toxins and sepsis mediators, with endotoxin, Pseudomonas exotoxin A, tumor necrosis factor alpha, interleukin-1 and nitric oxide being the most relevant ones identified. These substances interfere at clinically relevant concentrations with several main inotropic axes, not only with the beta-adrenoceptor/adenylyl cyclase and with the NO-cGMP-system-on which most of the interest is focused at present-but also with the alpha 1-adrenoceptor/phosphoinositide pathway and the Ca2+ homeostasis of the cardiomyocyte, the latter representing the common final inotropic pathway. Not a single cardiodepressant factor, but more likely a total bunch of toxins and mediators with different attack mechanisms seem to contribute to the picture of septic cardiomyopathy.

[Definition of shock types]

Definitions of shock types. Hypovolaemic shock is a state of insufficient perfusion of vital organs with consecutive imbalance of oxygen supply and demand due to an intravascular volume deficiency with critically impaired cardiac preload. Subtypes are haemorrhagic shock, hypovolaemic shock in the narrow sense, traumatic-haemorrhagic shock and traumatic-hypovolaemic shock. Cardiac shock is caused by a primary critical cardiac pump failure with consecutive inadequate oxygen supply of the organism. Anaphylactic shock is an acute failure of blood volume distribution (distributive shock) and caused by IgE-dependent, type-I-allergic, classical hypersensibility, or a physically, chemically, or osmotically induced IgE-independent anaphylactoid hypersensibility. The septic shock is a sepsis-induced distribution failure of the circulating blood volume in the sense of a distributive shock. The neurogenic shock is a distributive shock induced by generalized and extensive vasodilatation with consecutive hypovolaemia due to an imbalance of sympathetic and parasympathetic regulation of vascular smooth muscles.

Immune modulation by catecholamines--a potential mechanism of cytokine release in heart failure?

Cytokine blood levels are found to be moderately elevated in chronic heart failure, as a function of severity of disease. The source of these cytokines and the trigger mechanisms stimulating cytokine release are a matter of intense research. Potential players include bacterial endotoxin from intestinal translocation, a neurohumoral dysbalance with an enhanced sympathetic tone or an overspill of cytokines from the failing heart itself. We present arguments in favor of a direct link between the chronically enhanced sympathetic tone in heart failure and the clinically overt activation of the immune system, particularly interleukin 6 release.

Katecholamine im kardiogenen Schock: hilfreich, nutzlos oder gefährlich?

Cardiogenic shock is characterized by inadequate organ and tissue perfusion, due to cardiac dysfunction, predominantly following acute myocardial infarction. Mortality rates for patients with cardiogenic shock remain high, ranging from 50-70 % despite effective therapy. Rapid diagnostics, aggressive therapeutic approach (invasive or surgical revascularisation) and pharmacological support are currently used to improve the clinical outcome and survival. In the first line commonly sympathomimetics like dopamine, dobutamine, epinephrine and norepinephrine are used for the pharmacological treatment. They have a high affinity for alpha- and beta adrenergic receptors, leading to a positive inotropic cardiac function, an increase in heart rate, oxygen enhanced demand, and an increase in vasoconstriction. However, there are also some disadvantages in the use of sympathomimetics in patients with cardiogenic shock. Clearly, metabolic acidosis due to the increased oxygen demand can be observed. Vasoconstriction induced by sympathomimetics can lead to perfusion mismatch or even deficit within the microcirculation. Additionally, in some studies which give evidence that the use of sympathomimetics can directly lead to enhanced systemic inflammatory response due to an increased IL-6 expression. However, sympathomimetics are still first line therapeutics for treatment of cardiogenic shock -- with respect to dosage and duration of treatment.

Fibre-related nitric oxide synthase (NOS) in Duchenne muscular dystrophy

Nitric oxide (NO) mediates fundamental physiological actions on skeletal muscle. The loss of NO synthase (NOS) from the sarcolemma was assumed to be associated with development of Duchenne muscular dystrophy (DMD). We have, however, recently reported that, in contrast to the commonly accepted view, NOS expression in DMD myofibres is up-regulated. This poses the question of the fibre type-specific NOS expression in DMD muscles and how the NOS expression is related to the regeneration or degeneration status. To address this issue, we examined localization of NOS isoforms I, II and III in skeletal muscles of DMD patients employing immunohistochemical labelling with tyramide signal amplification complemented with enzyme histochemistry. We found that NOS immunolabelling as well as metabolic enzyme activity in DMD muscles were heterogeneously distributed along the fibre length of DMD muscle fibres revealing regenerating and degenerate (hypercontracted) fibres as well as normal segments. Like in normal muscles, positive NOS immunoreactivity was found to be associated with fast-oxidative glycolytic (FOG) phenotype. The regeneration status of NOS-positive segments was deduced from the presence of neonatal and developmental myosin heavy chains. High NOS expression in regenerating DMD muscle fibres can be well reconciled with reports about the protective role of endogenous NO in inflammatory diseases and in muscle repair.

Inflammation and ageing

An enhanced inflammatory state - i.e. "inflammatory/pathogen burden" - in the elderly on the one hand results from physiological immunosenescence and on the other hand is modified by the individual immune history: the latter is determined by sequential infectious/pathogenic events ("multiple hits"). Immunosenescence may prompt ageing of other organs. Cardiac ageing can be assessed by analysing heart rate variability. We present our hypothesis that the increasing "inflammatory/pathogen burden" of each organism during a lifetime significantly contributes to the cardiac ageing process. This hypothesis is grounded on the fact that a characteristic feature of the ageing heart - a narrowed heart rate variability - can be experimentally induced in humans by an inflammatory stimulus (endotoxin).

[Elderly patients with cardiovascular diseases]

What is the difference in cardio-vascular diseases in the elderly? - In elderly patients with acute coronary syndrome the diagnosis is frequently hampered by non-specific symptoms and these patients often seek medical help later than younger individuals. Elderly and old patients with acute coronary syndrome are still less frequently being referred to percutaneous coronary intervention (PCI) than younger patients, although statistically even octogenarians profit from PCI more than from thrombolysis or purely drug therapy. In stable coronary artery disease the focus is on consistent treatment of risk factors. Therapy of systolic heart failure in the elderly is not fundamentally different from that administered to younger individuals, and therapy is just as effective. In old age diastolic heart failure is frequent. The risk of thrombo-embolic complications in atrial fibrillation increases with age. What makes the difference in cardio-vascular diseases in the elderly? - Physiological organ aging processes and immunosenescence provide possible explanations for the frequently atypical clinical presentation of severe ailments and altered pharmacokinetics in old age. Influenza and pneumococcus vaccinations are effective in preventing cardiovascular events.

Heterogeneity of cardiac rat and human elongation factor 2

Elongation factor 2 (EF-2) catalyses the last step of the elongation cycle, translocation, in the course of protein biosynthesis. A system for analyzing post-translational modifications of EF-2, which is a single polypeptide of 857 amino acids, is reported and its application to cytosolic extracts of cultured neonatal rat heart myocytes, neonatal and adult rat cardiac tissue, and extracts of human left ventricular myocardium is described. Comparing different pH ranges in immobilized pH gradient-isoelectric focusing (IPG-IEF), a range of pH 3 - 10 and 4 - 9 resulted in a highly defined and reproducible resolution of six different EF-2 variants of all extracts in the first dimension. These six variants were detected by the "imaging plate" (phosphor radiation image sensor) after specific labeling with Pseudomonas exotoxin A catalyzed [32P]ADP-ribosylation. This finding could be confirmed in Western blot analysis with a specific polyclonal rabbit antibody. Using two-dimensional polyacrylamide gel electrophoresis (2-D-PAGE), five to six EF-2 variants could be demonstrated in all extracts. By application of a second IPG indicator strip to the 2-D gel, they could be aligned with corresponding spots in a silver-stained 2-D separation of human myocardial tissue, revealing that the EF-2 variants belong to the group of low-abundance proteins.

Autonomic Information Flow during awakeness, sleep, and multiple organ dysfunction syndrome assessed by mutual information function of heart rate fluctuations

The Autonomic Information Flow (AIF) represents the complex communication within the autonomic nervous system (ANS). It can be assessed by the mutual information function (MIF) of heart rate fluctuations (HRF). AIF represented by HRF is based on several interacting physiological mechanisms operating at different time scales. Therefore one prominent time scale for HRF complexity analysis is not given a priori. MIF reflects the information flow at different time scales. This allows a more specific characterization of the complex communication leading to dynamic stability (homeostasis) of the cardiovascular-respiratory system. Three clinically relevant examples of autonomic communication, namely AIF of normals during awake state and deep sleep, and of patients with multiple organ dysfunction syndrome (MODS) were investigated. In these states MIF clearly represents and distinguishes the different communication in dependence on the time scale of information transfer. The results confirm our systems-theoretical concept that AIF, represented by MIF, characterizes the complex communication of the ANS at different time scales.

Are the elderly different? Factors influencing mortality after percutaneous coronary intervention with stent implantation

BACKGROUND

The aim of this study was to investigate factors influencing mortality after percutaneous coronary intervention (PCI) in patients aged ≥ 75 years compared to younger patients.

PATIENTS AND METHODS

A total of 1,809 coronary heart disease (CHD) patients after PCI with stent implantation in our hospital were assessed. Kaplan-Meier analyses with log-rank test and Cox regression analyses were performed on three predefined models concerning primary endpoint of all-cause mortality. Model 1 was a univariate analysis of the influence of age dichotomized by age 75 years on the primary endpoint. Model 2 included age and classical cardiovascular risk factors (CVRFs, e.g., body mass index (BMI), smoking, diabetes, and hypertension). Model 3 consisted of age, classical CVRFs, and additional factors (e.g., medication; hemoglobin, peripheral arterial disease (PAD), low-density lipoprotein cholesterol (LDL-C) and creatinine levels, and left ventricular ejection fraction (LVEF)).

RESULTS

In the mean follow-up of 137 ± 61 weeks 375 patients died. Age ≥ 75 years was significantly related to mortality in all models. In model 3, previous stroke, PAD, diabetes, elevated levels of serum creatinine, and increased LDL-C were related to elevated mortality, higher hemoglobin levels, and LVEF > 50% were associated with decreased mortality in all patients and in patients < 75 years. In patients ≥ 75 years arterial hypertension was associated with poor outcome (hazard ratio (HR) 7.989, p = 0.040), previous antiplatelet therapy showed reduced mortality (HR 0.098, p = 0.039).

CONCLUSION

Although risk factors such as previous stroke, PAD, diabetes, renal insufficiency, and anemia were predictors for death in all patients and patients < 75 years, in the elderly only arterial hypertension increased, whereas treatment with platelet inhibitors decreased mortality.

Digital pen technology for conducting cognitive assessments: a cross-over study with older adults

Many digitalized cognitive assessments exist to increase reliability, standardization, and objectivity. Particularly in older adults, the performance of digitized cognitive assessments can lead to poorer test results if they are unfamiliar with the computer, mouse, keyboard, or touch screen. In a cross-over design study, 40 older adults (age M = 74.4 ± 4.1 years) conducted the Trail Making Test A and B with a digital pen (digital pen tests, DPT) and a regular pencil (pencil tests, PT) to identify differences in performance. Furthermore, the tests conducted with a digital pen were analyzed manually (manual results, MR) and electronically (electronic results, ER) by an automized system algorithm to determine the possibilities of digital pen evaluation. ICC(2,k) showed a good level of agreement for TMT A (ICC(2,k) = 0.668) and TMT B (ICC(2,k) = 0.734) between PT and DPT. When comparing MR and ER, ICC(2,k) showed an excellent level of agreement in TMT A (ICC(2,k) = 0.999) and TMT B (ICC(2,k) = 0.994). The frequency of pen lifting correlates significantly with the execution time in TMT A (r = 0.372, p = 0.030) and TMT B (r = 0.567, p < 0.001). A digital pen can be used to perform the Trail Making Test, as it has been shown that there is no difference in the results due to the type of pen used. With a digital pen, the advantages of digitized testing can be used without having to accept the disadvantages.