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W Engelhardt

Publications and source records attributed to W Engelhardt.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effect of sodium nitroprusside on complement activation induced by cardiopulmonary bypass: a clinical and experimental study.

Complement activation and leukocyte stimulation were prospectively studied during and after cardiopulmonary bypass in 16 children receiving sodium nitroprusside--a nitrovasodilator releasing nitric oxide--for vasodilation during the cooling and rewarming periods of extracorporeal circulation. Results were compared with those in 29 patients who were not treated with sodium nitroprusside during the operation. Patients treated with sodium nitroprusside had significantly less C3 conversion during cardiopulmonary bypass as measured by the ratio C3d/C3 (p <0.05) and significantly less C5a liberation immediately after cardiopulmonary bypass (p < 0.005) than patients not treated with sodium nitroprusside. C4 was not overtly consumed in our series. Leukocyte count during the rewarming period of cardiopulmonary bypass, but not leukocyte elastase release during cardiopulmonary bypass, was significantly reduced in patients treated with sodium nitroprusside (p <0.05). In vitro experiments were conducted to analyze the effect of sodium nitroprusside on complement hemolytic activity initiated by the classic and the alternate pathways and on zymosan-induced C3 conversion by the activation of the alternate pathway. The in vitro experiments clearly demonstrate inhibition of complement hemolytic activity by sodium nitroprusside in the sera tested. The 50% inhibitory concentration of sodium nitroprusside on the available complement hemolytic activity was less through the alternate pathway than through the classic one (4.2 +/- 0.8 mmol/L and 14.0 +/- 2.88 mmol/L, respectively). The decrease of complement hemolytic activity measured was dose-dependent and was enhanced by the sodium nitroprusside preincubation of the sera tested. This effect was related to the duration of preincubation. Sodium nitroprusside photodegradation (enhancing nitric oxide release) increased the anticomplementary effect of the drug, reducing the 50% inhibitory concentration on complement hemolytic activity to 0.24 to 0.02 mmol/L for the alternate pathway and 2.74 o 0.3 mmol/L for the classic pathway. the zymosan-induced C3 conversion was inhibited by sodium nitroprusside. Nitroglycerin and isosorbide dinitrate (other nitric oxide donors) had in vitro effects on complement hemolytic activity similar to those of nonphotodegraded sodium nitroprusside at similar concentrations (1 mmol/L). Our results suggest that sodium nitroprusside, both in vitro and in vivo, has an inhibiting effect on complement activation initiated by both classic and alternate pathways and that this effect is mediated by nitric oxide release from sodium nitroprusside. This is the first report on the anticomplementary effect of sodium nitroprusside by nitric oxide release.

Cardiopulmonary Bypass↗
PubMed1996

Malignant hyperthermia (MH) diagnostics: a comparison between the halothane-caffeine- and the ryanodine-contracture-test results in MH susceptible, normal and control muscle.

Recent studies demonstrated different contracture responses in muscle from malignant hyperthermia susceptible (MHS) compared to normal (MHN) individuals following exposure to the plant alkaloid ryanodine in-vitro. To confirm if ryanodine has a specific action in MHS muscle, the effect of a single concentration was investigated in skeletal muscle from MHS, MHN and control subjects using a new evaluation technique. In-vitro contracture test (IVCT) and MH diagnosis were performed according to the European Protocol in 86 patients sent to us for MH diagnostic testing and in 24 controls. Viable fresh muscle bundles were exposed to a single bolus of ryanodine 1.0 microM. Contracture onset time (OTp: defined as the time (min) from administration of ryanodine to the start of a contracture as measured by a contracture exceeding predrug baseline height), and the time to an increase of the baseline height to 10 mN above the predrug level (10Tp) were recorded. 29 patients were identified by IVCT to be MHS, 50 MHN, 7 MHE (equivocal) and 24 controls MHN. The indices from the ryanodine test separated all MHS (OTp: < 16 min; 10Tp < 27.4 min) from MHN (> 18 and > 27.7 min) and control subjects (> 17.4 and > 29 min). Values for MHE (equivocal) individuals ranged from 17.1 to 27.8 min for the OTp and from 32 to 49.2 min for the 10Tp. 5 patients with fulminant MH crises were included in the MHS group and showed the 95% confidence intervals (CI) of the median value < or = 8.05 min (OTp) and < or = 13.35 min (10TP) for MHS. In contrast, CI of the median value for the control group were found to be > or = 25.2 min (OTp) and 43.15 min (10Tp) for normal muscle. Thus the ryanodine test protocol showed markedly different contractures in MHS and MHN or control muscle. These results suggest that MHS muscle has a higher sensitivity to ryanodine. However, the protocol should be investigated for reproducibility and validation of thresholds by other laboratories. Ryanodine can help to improve MH diagnostic tests.

Adolescent↗
PubMed1996

Early cerebral functional outcome after coronary artery bypass surgery using different acid-base management during hypothermic cardiopulmonary bypass.

BACKGROUND: Cerebral injury can render meaningless an otherwise successful cardiac operation. As carbon dioxide management during hypothermic cardiopulmonary bypass has a major impact on cerebral blood flow during bypass, it may also influence postoperative cerebral function. The objective of this prospective, controlled, double-blind study was to compare the effect of pH-stat (temperature correction of blood gas analyses) or alpha-stat (no temperature correction) on brain function. METHODS: Cerebral function was assessed non-invasively using neurological examination, a neuropsychological test battery, quantitative electroencephalogram and the cognitive evoked potential P300 preoperatively and on postoperative day 7 or 8. Forty-five patients undergoing elective aortocoronary bypass grafting in barbiturate/opiate anesthesia were randomised into a pH-stat-(n = 23) and an alpha-stat-group (n = 22). Membrane oxygenators with arterial line filtration and non-pulsatile flow at a perfussion pressure of 50-60 mmHg were used throughout. RESULTS: One patient in each group developed a new paresis. Among 49 comparisons of cerebral function parameters, only 3 showed significant differences at the 5%-level, i.e. exactly what is expected purely by chance. These differences were too small to be clinically relevant and favored either pH-stat (theta-amplitude) or alpha-stat (subtest 3 of syndrome-short-test, number of mistakes in aiming). CONCLUSION: Under the bypass conditions of this study there was no difference in early cerebral functional outcome between pH-or alpha-stat carbon dioxide management during hypothermic cardiopulmonary bypass.

Acid-Base Equilibrium↗
PubMed1995

Activation-dependent expression of low affinity IgG receptors Fc gamma RII(CD32) and Fc gamma RIII(CD16) in subpopulations of human T lymphocytes.

Receptors for IgG (Fc gamma R) are expressed by small subpopulations of peripheral blood T lymphocytes. Our studies demonstrate that T lymphocytes can be induced in vitro to express two different low-affinity Fc gamma R. Mitogen activation of peripheral blood T lymphocytes obtained from eight healthy individuals leads to considerable augmentation of the Fc gamma RIII+ (CD32) T cell subpopulation. The highest percentage of CD32 expressing T lymphocytes could be detected after three days of activation. The T cell subpopulation which transiently express the CD32 antigen, encompasses CD4+ and CD8+ cells. Molecular cloning of the CD32 antigen by reverse transcription and polymerase chain reaction demonstrates that activated human T lymphocytes express the Fc gamma RIIIb2 isoform. The percentage of the Fc gamma RIII+ (CD16) T cell subpopulation was significantly increased only in the lymphocyte populations obtained from three out of eight volunteers immediately after mitogen activation. However, during short-term cell culture the CD16 expressing CD8+ T cell subset increased in the T cell population from all individuals investigated. During this time, the IL-2 receptor alpha-chain (CD25) expression level decreased as a function of time. In contrast to the CD8+CD16+ T cells, the percentage of the non-MCH-restricted CD56+CD16+ T cells was not influenced by mitogen activation and time of cell cultivation. We could show that CD16 in T cells is able to mediate a stimulus leading to proliferation of the CD8+CD56-CD16+ T cells but not that of the CD56+CD16+ T cell subset. This discrepancy cannot be explained by the expression of different Fc gamma RIII isoforms, because both T cell subsets express Fc gamma RIIIA alpha, as we demonstrate in this report.

Antibodies, Monoclonal↗
PubMed1995

P300-mapping--a neurophysiological tool to quantify cerebral dysfunction after coronary artery bypass grafting.

Objective parameters are needed to quantify cerebral dysfunction following cardiac surgery in outcome and comparative studies. In this investigation we assessed the value of the late auditory evoked potentials N100 and P300 to measure the neuropsychological deficit after coronary artery bypass grafting (CABG). N100, an exogenous potential is influenced by the stimulus pattern (frequency, intensity and stimulus presentation rate). P300, an endogenous potential, depends on the cognitive processing invoked by the stimulus. With approval of the Human Investigation Committee and the patients' consents, 52 subjects undergoing elective CABG were enrolled. Operation, extracorporal circulation, anesthesia and postoperative intensive care were standardized. Twenty-channel recordings of N100 and P300 were obtained for off-line analysis. P300 was elicited using an oddball paradigm with rare target tones interspersed among frequent non-target tones. Additionally, neuropsychological tests (syndrome short test SKT and letter cancellation test) were carried out. Neurological examination and all tests were compared preoperatively and one week postoperatively. A significant deterioration in cerebral function was documented by the SKT score (P = 0.04), an increase in P300 latency (P = 0.004) and an increase of mistake rate in counting the P300 target tone (P = 0.02). No differences between preoperative and postoperative testing were found for letter cancellation, P300 amplitude and any N100 parameter. No correlation was found between the preoperative/postoperative changes in SKT score and P300 latency. P300 was proved to be an objective neurophysiological parameter that allows for the quantification of cerebral function after CABG.

Aged↗
PubMed1994

Cardiac involvement in tuberous sclerosis.

OBJECTIVE: To assess the incidence, importance, and history of cardiac involvement in infants and children with tuberous sclerosis. DESIGN: Prospective study; clinical examination, sector and Doppler echocardiography, standard and ambulatory electrocardiography. SETTING: A tertiary referral centre. PATIENTS: 21 patients with tuberous sclerosis aged 1 day to 16 years (mean 6.3 years); follow up investigations were available in 14 cases (10 retrospective, 4 prospective; mean follow up 4.3 years). RESULTS: Multiple cardiac rhabdomyomas in the right ventricle (11) and left ventricle (14) as well as in the right atrium (1) were present in 14/21 patients. Two of them had obstruction of the left ventricular inflow and outflow tract related to a tumour. In the remaining 7 patients, echocardiography was normal in 4 and equivocal in 3 cases. The standard electrocardiogram (n = 20) showed ventricular hypertrophy (2), ventricular pre-excitation (1), arrhythmias (2), and repolarisation disturbances (4) in 7/13 patients with rhabdomyomas but was normal in all patients with a normal or equivocal echocardiogram. The ambulatory electrocardiogram (n = 19) showed frequent premature atrial (2) and polymorphous ventricular (2) contractions. The polymorphous ventricular contractions coexisted with rhabdomyomas. No arrhythmias that needed medical treatment were found. Follow up investigations showed return to a normal standard electrocardiogram in 3 patients. Definite regression or complete disappearance of the tumour occurred in 6 infants. CONCLUSIONS: Cardiac rhabdomyomas, although often present in these patients with tuberous sclerosis, caused neither major arrhythmias nor haemodynamic obstruction except in the neonatal period. The indication for operation is limited to cases with life threatening obstruction or arrhythmias refractory to medical treatment.

Adolescent↗
PubMed1994

[Ketamine racemate versus S-(+)-ketamine with or without antagonism with physostigmine. A quantitative EEG study on volunteers].

The potency of S-(+)-ketamine is approximately double that of the racemic ketamine. This study was carried out to investigate the recovery of cerebral electrical function after a bolus of 1.3 mg/kg ketamine or 0.65 mg/kg S-(+)-ketamine and subsequent continuous application of 4 mg/kg h ketamine per h or 2 mg/kg S-(+)-ketamine, per h for 15 min. Furthermore, the centrally acting, cholinergic agonist physostigmine has been reported to antagonize ketamine and to shorten the recovery period. Therefore, after S-(+)-ketamine 0.012 mg/kg physostigmine was tested against saline placebo. METHODS. With their own informed consent and the approval of the ethics committee 12 healthy volunteers were enrolled in a double-blind cross-over study. All drugs were dissolved in identical volumes. On three dates with intervals of at least 1 week between, ketamine/NaCl, S-(+)-ketamine/physostigmine or S-(+)-ketamine/NaCl was administered (Table 1). The sequence was randomized. The EEG was recorded from 20 sites according to the 10/20 system and after Fast-Fourier transformation computed into amplitudes within the delta, theta, alpha, and beta bands and within the total spectrum. The median, the spectral edge frequency and the dominant frequency (dF) were also determined. Mean values of all electrodes before and at 10, 15, 30, 45 and 195 min after the bolus injection were compared using two-dimensional analysis of variance (ANOVA, significance level P < 0.05). RESULTS. The characteristic increase in theta-amplitude and decrease of alpha-amplitude were observed after ketamine and S-(+)-ketamine. Median and dF dropped from the alpha to the theta frequency range. Ketamine led to a greater increase in total, delta, theta and beta amplitude during anaesthesia. 3 hours after ketamine/S-(+)-ketamine anaesthesia a significant decrease in the median and dominant frequency and in total, delta, theta, alpha and beta amplitudes confirmed residual impairment of cerebral function after all study drugs. No differences were found between physostigmine and placebo. DISCUSSION. The EEG changes during ketamine/S-(+)-ketamine administration suggest a slightly deeper anaesthetic level after ketamine. The course of recovery was not different after ketamine and after S-(+)-ketamine. The spectral edge frequency did not differ between measurement points, and is therefore not suitable for assessment of the depth of anaesthesia reached with ketamine/S-(+)-ketamine. The dose of physostigmine tested was probably too low to produce antagonism of S-(+)-ketamine. An increased dosage of physostigmine has yet to be studied, but is likely to cause a higher rate of side effects, such as nausea, vomiting and bradycardia, and possibly even tonic-clonic seizures.

Adolescent↗
PubMed1993

Interleukin-2, soluble interleukin-2-receptor, neopterin, L-tryptophan and beta 2-microglobulin levels in CSF and serum of patients with relapsing-remitting or chronic-progressive multiple sclerosis.

Cerebrospinal fluid (CSF) and serum levels of interleukin-2 (IL-2), soluble IL-2 receptors (sIL-2R), neopterin, L-tryptophan (L-TRP) and beta 2-microglobulin (beta 2-M) were measured in 31 untreated multiple sclerosis patients in acute exacerbation and 27 normal controls. Twenty-six patients showed the relapsing-remitting type of disease (RRMS); 5 had a chronic-progressive course (CPMS). No changes in serum IL-2 and sIL-2R were found between RRMS patients and controls, whereas serum and CSF levels as well as the CSF/serum ratio of neopterin were significantly elevated in the RRMS group. IL-2 was not detectable in CSF of patients or controls and sIL-2R levels were at the level of the lower detection (LD) sensitivity of the ELISA method. Four of 23 RRMS patients versus 1 of 25 controls showed CSF sIL-2R levels above the LD sensitivity, indicating a trend towards elevation in acute relapse. No difference was found in serum and CSF L-TRP and beta 2-M of patients and controls. In CSF of RRMS patients neopterin and L-TRP correlated negatively, reflecting the interferon-gamma mediated activation of macrophages in acute relapse. A significant positive correlation (Spearman rank 0.57, P = 0.001) between serum IL-2 levels and duration of acute relapse (mean 30 days) warrants further evaluation.

Acute Disease↗
PubMed1993

Equivalent dipoles of FFT data visualize drug interaction at benzodiazepine receptors.

The aim of the present investigation was to study if the benzodiazepine receptor antagonist flumazenil could reverse the effects on the brain electrical activity induced by the benzodiazepine receptor agonist midazolam. The method of FFT approximation was used for this purpose. It allows the calculation of center of gravity equivalent dipoles of spectral EEG data. The results are reference independent and allow therefore a more unambiguous interpretation compared to conventional FFT data reports. Twelve subjects were investigated before and after 0.1 mg/kg and 0.2 mg/kg midazolam respectively, directly and 4 h after administration of 1 mg flumazenil. Our results imply that the application of flumazenil after midazolam sedation leads to an almost complete restoration of the brain electrical activity. However, especially in the beta frequencies above 20 Hz differences in depth of equivalent dipoles were found directly after flumazenil application as well as 4 h later. This could suggest that neuronal generators in different brain structures were responsible for the electrical activity after flumazenil administration compared to before.

Adult↗
PubMed1993

Multiple system organ failure after open heart surgery in infants and children.

Between January 1985 and March 1989 we retrospectively observed multiple system organ failure (MSOF) in 16 of 460 children (3.5%) who underwent cardiac surgery with cardiopulmonary bypass for congenital heart disease. MSOF was arbitrarily defined as a clinical entity with failure of two or more vital organ systems associated with high fever, thrombocytopenia, and cardiocirculatory insufficiency and occurring within the first postoperative week. In 13 children the first clinical manifestations of MSOF were evident on the first post-operative day and in the other 3 on the second or third post-operative day. All children showed acute renal failure, acute hepatic failure, high fever, and thrombocytopenia. Most of them showed respiratory insufficiency and neurological involvement. Seven of the 16 children died. Four of the 9 surviving patients had neurological sequelae still present 6 months after the operation, and the others recovered completely.

Cardiac Surgical Procedures↗
PubMed1993

Receptor binding of osteoblast-specific factor 1 (OSF-1/HB-GAM) to human osteosarcoma cells promotes cell attachment.

OSF-1/HB-GAM is a member of developmentally regulated growth factors and cytokines. High expression levels of this factor are found in different tissues, e.g., in brain and in bone. We have analyzed the biological function and binding properties of natural OSF-1 to human osteoblasts. Using antibodies raised against the entire OSF-1 molecule or a synthetic carboxy-terminal peptide (amino acids (aa) 110-140) we have investigated the binding sites of rat OSF-1 on human osteoblast-like osteosarcoma cell lines: HOS(TE85) and MG-63. Immunofluorescence microscopic studies and flow cytometric data revealed that OSF-1 is specifically bound to the surface of these cells. Further characterization of the binding sites showed that both osteosarcoma cells express two different kinds of binding sites: Besides binding to a specific OSF-1 receptor, OSF-1 also significantly binds to cell surface heparan sulfates. Using the peptide specific polyclonal antibody we show that the carboxy-terminal domain, aa 110 to 140 of OSF-1, seems to be involved in ligand binding. Studies on the biological function of OSF-1 revealed a strong cell attachment promoting activity in vitro. This activity is not diminished after digestion of cell surface heparan sulfates by heparinase I and heparitinase I, demonstrating that the OSF-1 receptor mediates the cell attachment of osteoblasts. Our results indicate that one biological function of OSF-1 is the promotion of osteoblast attachment to the extracellular bone matrix.

Amino Acid Sequence↗
PubMed1993

Intra-individual open comparison of burst-suppression-isoflurane-anaesthesia versus electroconvulsive therapy in the treatment of severe depression.

Isoflurane anaesthesia was proposed instead of electro-convulsive therapy (ECT) in patients with treatment-refractory depression. This open study compared burst-suppression-isoflurane-anaesthesia (BSIA) and ECT in 12 severely depressed patients. A series of 6 BSIA was administered in every patient. If improvement was insufficient or only temporary, a series of up to 12 ECT was given. A marked improvement of the depression was shown after both BSIA and ECT. Three patients were discharged from hospital after BSIA, nine patients were treated with BSIA and then ECT. The therapeutic effect of both regimens was equal as evidenced by the Hamilton-depression-rating-scale, a visual-analog-scale and the clinical global impression. BSIA requires more time and monitoring than ECT. Our exclusions of coronary, cerebral and peripheral vascular disease, untreated hypertension and focal neurological disease are strongly recommended. Due to the ease of application, ECT remains the standard treatment in depressed patients, but we consider BSIA a valuable alternative at least in patients who object to ECT.

Adult↗
PubMed1992

Internal mammary artery bypass graft for impaired coronary perfusion after neonatal arterial switch operation.

Myocardial ischaemia caused by perfusion impairment of translocated coronary arteries is the major cause of perioperative mortality after neonatal arterial switch operation for transposition of the great arteries. We report the successful use of the right internal mammary artery as a bypass graft to a dominant right coronary artery to treat insufficient perfusion of this artery in a newborn. Eight months later, coronary angiography showed a full blood supply of the right coronary artery across the internal mammary anastomosis. After a follow-up period of more than 30 months, somatic development, electrocardiogram and echocardiographically determined contractility of both ventricles are practically normal indicating regular function of the bypass graft.

Coronary Angiography↗
PubMed1992

Quantitative topographical analysis of effects of single thiopental bolus on human electroencephalogram.

The aim of present study was to characterize the topographical effect of thiopental on the EEG during induction of anesthesia. A multichannel (19 channels) digital EEG was recorded in 10 patients undergoing surgical treatment. The period during induction of anaesthesia before intubation was investigated in regard to peak frequency, amplitude, topography, and amplitude in conventional frequency bands. The main findings were a slowing of the EEG with a simultaneous increase of amplitude in the predominant EEG frequency (peak frequency) during induction. The topographical analysis showed a clear change of localization of the peak frequency in the occipito-frontal direction. Berger described the effect of thiopental on electrical cortical activity as early as 1933. Since then, many studies have investigated its influence on the EEG, but few have tried to characterize the effects of topographical changes in a quantitative way.

Adult↗