Biomedical subjects

Michael Walter

Publications and source records attributed to Michael Walter.

25 records · Page 2Linked to original sources

PubMed2004

Primary endothelial sarcoma of the thoracic aorta.

Primary malignant tumors of the aorta are extremely rare. The case of a 64-year-old woman who presented with peripheral embolism to both femoropopliteal arteries is reported. The search for a source revealed a polypoid lesion severely narrowing the lumen of the distal thoracic aorta. Differential diagnosis included thrombus and primary aortic tumor. Extirpation of the tumorous lesion was performed. Histologic examination revealed intimal aortic sarcoma of endothelial cell origin. Although the liver was the only site of suspected metastases at the time of operation, during the 18-month follow-up until the patient's death, generalized metastatic spread had developed. This case report thus demonstrates the generally poor prognosis of this rare variety of aortic sarcoma, in particular when symptoms have already occurred.

Aorta, Thoracic↗

PubMed2003

Reversible cardiac sympathectomy by high thoracic epidural anesthesia improves regional left ventricular function in patients undergoing coronary artery bypass grafting: a randomized trial.

HYPOTHESIS: To evaluate the effects of high thoracic epidural anesthesia (TEA) on global and regional myocardial function and on perioperative coronary risk in patients undergoing coronary artery bypass grafting. DESIGN, SETTING, AND PATIENTS: Prospective and randomized clinical trial blinded for the primary outcome measure of 73 patients scheduled for coronary artery bypass grafting who had a left ventricular ejection fraction of 50% or more conducted from February 1, 2000, through August 31, 2000, at University Hospital, Münster, Germany. INTERVENTIONS: Of 73 randomized patients, 37 were control subjects (who received general anesthesia only) and 36 were in the group who received general anesthesia and high TEA. MAIN OUTCOME MEASURES: The primary outcome measure was regional left ventricular function after myocardial revascularization, assessed by transesophageal echocardiography. We further determined the plasma concentrations of cardiac troponin I and atrial and brain natriuretic peptides. Secondary outcome measures were postoperative complications recorded to 14 days and mortality recorded to 720 days. RESULTS: High TEA was effective in all patients of this group, the somatosensory block extended from T1 through T7 vertebrae. Regional left ventricular function was significantly improved (mean [SD] global wall motion index, 0.74 [0.18] vs 0.38 [0.16]; P<.05), and cardiac troponin I concentrations were reduced by 72% (mean [SD], 5.7 [1.5] vs 1.6 [0.7] ng/mL, P<.05) in patients with high TEA. Natriuretic peptide concentrations peaked during reperfusion (atrial natriuretic peptide) and 24 hours after reperfusion (brain natriuretic peptide). High TEA reduced the mean (SD) peak concentrations of atrial natriuretic peptide by 54% (211 [63] vs 98 [33] ng/mL, P =.03) and brain natriuretic peptide by 43% (189 [39] vs 108 [21] ng/mL, P =.01). One of 36 patients who received high TEA and 3 of 37 controls died. CONCLUSIONS: Reversible cardiac sympathectomy by high TEA improves regional left ventricular function and reduces postoperative ischemia after coronary artery bypass grafting. These effects of high TEA may improve the long-term outcome after myocardial revascularization.

Anesthesia, Epidural↗

PubMed2003

Haemoglobin-related mortality in patients undergoing percutaneous coronary interventions.

AIMS: It has recently been proposed that anaemia is an independent risk factor for development of cardiovascular disease in the general population. The impact of anaemia on long-term survival of patients with manifest coronary heart disease (CHD) has not been assessed so far. In this study, we examined the influence of haemoglobin concentrations on the outcome after percutaneous coronary interventions (PCI). METHODS AND RESULTS: In a retrospective cohort study, we analysed in-hospital and long-term mortality in all male patients admitted to our institution for elective PCI from 1998 to 1999. In 689 cases, complete follow-up information could be obtained (98.4%). Depending on their baseline haemoglobin, patients were divided in quintiles. In all subgroups, angiographic success after PCI (90-94%) was comparably high and in-hospital mortality was low (0-0.7%). During follow-up (median 697 days), patients in the lowest haemoglobin quintile (</=12.9g/dl) were significantly more likely to suffer from all-cause death (22.2%) than those of the other quintiles (3.7-12.1%; estimated mortality rates from Kaplan-Meier models, P<0.0001, log rank test). In more detail, we found a U-shaped relationship between mortality and haemoglobin strata in steps of 1g/dl (P<0.0001, log rank test). After adjustment for potential co-variates, patients of the lowest haemoglobin quintile showed in Cox regression analysis a markedly higher risk for death (adjusted hazard rate ratio (HRR) 4.09, 95% confidence interval (CI) 1.52-11.05) compared to the quintile with a haemoglobin concentration of 14.6-15.2g/dl. CONCLUSIONS: These results indicate that anaemia is associated with markedly reduced survival in patients with CHD after elective PCI. Since PCI is a common intervention and anaemia is a frequent condition in the general population, strategies for the management of anaemic PCI patients and treatment of anaemic patients with CHD should be developed.

Analysis of Variance↗

PubMed2003

Endogenous glycosides in critically ill patients.

OBJECTIVE: To determine the incidence of critically ill patients displaying endogenous digitalis-like-immunoreactive substances (DLIS) and to examine the relationship of these hormones to routine laboratory variables, the underlying disease, myocardial function, hemodynamic status, severity of illness, systemic inflammation, and mortality rate. DESIGN: Sera of 401 consecutive critically ill patients, not treated with cardiac glycosides, were analyzed for DLIS (digitoxin and digoxin, TDx; Abbott Diagnostics, North Chicago, IL) and endogenous ouabain. Normal values of endogenous ouabain were determined in 62 healthy volunteers. We measured pro- and anti-inflammatory mediators (L-selectin, tumor necrosis factor-alpha, interleukin-1beta, interleukin-2, interleukin-6, interleukin-10), C-reactive protein, and serum amyloid A protein as well as patients' Acute Physiology and Chronic Health Evaluation II and Goris scores. In a subgroup of patients with a pulmonary artery catheter (n = 95), we determined cardiac output, pulmonary artery occlusion pressure, systemic and pulmonary vascular resistance, left ventricular stroke volume, and right and left stroke work. SETTING: Two surgical intensive care units of an university hospital. SUBJECTS: Sera of 401 consecutive critically ill patients. INTERVENTIONS: Blood sampling. MEASUREMENTS AND MAIN RESULTS: Of the 401 patients tested, 343 had nonmeasurable DLIS concentrations (DLIS-negative), and 58 (14.5%) had positive digoxin (n = 18) or digitoxin (n = 34) concentrations (DLIS-positive) or were positive in both tests (n = 6). Mean endogenous ouabain concentrations were nine-fold increased in DLIS-positive (3.59 +/- 1.43 nmol/L) and three-fold increased in DLIS-negative (1.34 +/-.81 nmol/L) patients compared with controls (0.38 +/- 0.31 nmol/L). DLIS and ouabain concentrations closely correlated with the Acute Physiology and Chronic Health Evaluation II and Goris score and were associated with increased concentrations of transaminases, bilirubin, aldosterone, cortisol, serum creatinine, fractional sodium excretion, proinflammatory mediators, C-reactive protein, and serum amyloid A (p <or=.009). The hospital mortality rates of DLIS-positive and DLIS-negative patients were 12% and 3.2%, respectively, and for patients with ouabain concentrations above and below 2 nmol/L 38.6% and 0.6%, respectively. In DLIS-positive patients with pulmonary artery catheter (n = 23), cardiac output, stroke volume, and left ventricular stroke work were decreased, and pulmonary artery occlusion pressure and central venous pressure were increased (p <or=.009). CONCLUSIONS: Different types of endogenous glycosides including endogenous ouabain are elevated in a significant proportion of critically ill patients. The occurrence of these substances is associated with increased morbidity and hospital mortality rates, possibly due to systemic inflammatory processes. DLIS but not endogenous ouabain concentrations were found to be related to left ventricular function.

APACHE↗

PubMed2002

PNPase activity determines the efficiency of mRNA 3'-end processing, the degradation of tRNA and the extent of polyadenylation in chloroplasts.

The exoribonuclease polynucleotide phosphorylase (PNPase) has been implicated in mRNA processing and degradation in bacteria as well as in chloroplasts of higher plants. Here, we report the first comprehensive in vivo study of chloroplast PNPase function. Modulation of PNPase activity in Arabidopsis chloroplasts by a reverse genetic approach revealed that, although this enzyme is essential for efficient 3'-end processing of mRNAs, it is insufficient to mediate transcript degradation. Surprisingly, we identified PNPase as also being indispensable for 3'-end maturation of 23S rRNA transcripts. Analysis of tRNA amounts in transgenic Arabidopsis plants suggests a direct correlation of PNPase activity and tRNA levels, indicating an additional function of this exoribo nuclease in tRNA decay. Moreover, the extent of polyadenylated mRNAs in chloroplasts is negatively correlated with PNPase activity. Together, our results attribute novel functions to PNPase in the metabolism of all major classes of plastid RNAs and suggest an unexpectedly complex role for PNPase in RNA processing and decay.

Arabidopsis↗

PubMed2002

Hyponatremia in a pediatric stroke patient: syndrome of inappropriate antidiuretic hormone secretion or cerebral salt wasting?

OBJECTIVE: To determine the potential role of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in the pathogenesis of cerebral salt wasting. DESIGN: Clinical case report. SETTING: Regional pediatric intensive care unit. PATIENT: A 3-yr-old boy with a cerebral infarct secondary to traumatic carotid artery dissection who developed hyponatremia associated with weight loss and excessive renal sodium excretion on the sixth day after hospitalization. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations of ANP, BNP, antidiuretic hormone, and renin were determined serially and compared with concentrations measured in a group of eight healthy children undergoing elective surgical procedures. Compared with controls, ANP and BNP plasma concentrations on the eighth day after hospitalization were increased 1.9-fold and 7.7-fold, respectively. Thereafter, the course of ANP and BNP paralleled that of sodium and H2O excretion and remained elevated until the 14th (BNP) and 16th (ANP) days after hospitalization. Serum antidiuretic hormone and renin concentrations were within normal ranges during the entire observation period. CONCLUSION: Cerebral salt wasting is associated with elevated plasma concentrations of ANP and BNP. Natriuretic peptides may play a role in the pathogenesis of this syndrome.

Atrial Natriuretic Factor↗

PubMed2002

Radical thoracoscopic lobectomy with lymphadenectomy in a cadaver model.

OBJECTIVE: Because the standard thoracoscopic lobectomy in bronchial carcinoma is often criticized for assumed incomplete lymph-node dissection and oncologic radicality, thoracoscopic lymphadenectomy (TL) was investigated as one step of a scientific investigation for developing a method of complete thoracoscopic resection of bronchial carcinoma. DESIGN: A cadaver model (n = 13) was used to investigate the technique of thoracoscopic radical hilar lobectomy and mediastinal lymphadenectomy. INTERVENTION: TL followed by a large anterolateral exploratory thoracotomy to evaluate the safety and radicality of TL. RESULTS: The mean (and standard deviation) number of lymph nodes resected was 15.6 (4.3). On follow-up exploration, no residual tissue was found at the hilar stump or residual lymph nodes. No other intrathoracic lesions were found. CONCLUSIONS: TL with radical hilar and mediastinal lymphadenectomy by the described tehcnique can be accomplished according to current oncologic regulations.

Cadaver↗