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Biomedical subjects

W Engelhardt

Publications and source records attributed to W Engelhardt.

At least 19 recordsLinked to original sources
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↗
PubMed1992

EEG and auditory evoked potential P300 compared with psychometric tests in assessing vigilance after benzodiazepine sedation and antagonism.

We have compared the EEG and auditory evoked wave P300 with psychometric tests in assessing vigilance after flumazenil antagonism of midazolam sedation in 12 healthy volunteers. Measurements were made before and after midazolam 0.1 and 0.2 mg kg-1 i.v., and immediately and 30, 60, 120 and 240 min after administration of flumazenil 1 mg. The sedative effects of midazolam and antagonism by flumazenil resulted in alterations in EEG, P300 and psychometric tests (syndrome short test, letter cancellation, choice reaction and recognition). However, 60 and 120 min after flumazenil a decrease in test performance indicating rebound sedation was seen only in P300 mapping. Thus P300 mapping was a sensitive method of detecting subtle differences in vigilance. Rebound sedation occurred even when midazolam 0.2 mg kg-1 was antagonized with an adequate dose of flumazenil. We suggest that it is advisable to supervise patients for at least 240 min after flumazenil antagonism of midazolam 0.2 mg kg-1.

Adult↗
PubMed1992

Atrial automatic tachycardia in infancy and childhood.

Twenty-one cases (13 male, eight female) of atrial automatic tachycardia (AAT) assessed by standard and Holter-ECG in otherwise healthy infants and children have been documented. AAT was incessant in 12 patients, repetitive in seven, and of undetermined type in the remaining two. The frontal P wave axis suggested an ectopic focus in the high right atrium or right atrial appendage in 13 patients, in the low right atrium in one patient, and in the left atrium in seven patients. Thirteen out of 14 patients with the incessant or undetermined type of AAT were symptomatic, in contrast to only two of seven patients with the repetitive type. All patients were treated with between one and eight (median three) antiarrhythmic drugs. The most effective drug was amiodarone, followed by the class I C antiarrhythmic drugs, propafenone and flecainide. At present, all patients are alive 4 months to 21 years (median 2.5 years) after diagnosis of AAT. Twelve patients are in sinus rhythm, five of them without any medication. Nine patients still have AAT, which, however, is repetitive or intermittent in all but one. In conclusion, AAT is an unusual, and in its incessant form often severely symptomatic arrhythmia, which is resistant to conventional antiarrhythmic medication. However, amiodarone and class I C antiarrhythmic drugs are frequently effective. Since medical treatment with these drugs is often successful, and AAT may resolve completely, a conservative approach is indicated in many cases.

Adolescent↗
PubMed1992

Detection of sinus venosus atrial septal defect by two-dimensional echocardiography.

In a 4-year period, 10 patients (mean age, 3.6 years) with a superior type sinus venosus atrial septal defect were investigated by two-dimensional echocardiography. The defects were easily visualized in all patients using a long axis vena cava superior-inferior plane with a subcostal approach, while the atrial septum seemed to be intact in the coronal plane conventionally used for atrial septal defects of the primum or secundum type. Additional colour flow mapping, performed in two patients, demonstrated shunting across the depicted defect. In our experience, the modified plane is of great diagnostic value in cases with a sinus venosus defect.

Child, Preschool↗
PubMed1992

[Suppression of the adrenal cortex by enoximone. A proband study with documentation of the hemodynamic course].

In contrast to the bipyridine derivatives amrinone and milrinone, the phosphodiesterase III/IV inhibitor enoximone is an imidazolone that creates the possibility of inhibiting adrenal steroid synthesis, as has already been demonstrated for other imidazoles, e.g. ketoconazole and etomidate. To clarify this point we carried out a double-blind sequential study in seven healthy volunteers. METHODS. After obtaining the approval of the ethics committee and the written consent of the volunteers, 1.25 mg/kg enoximone or saline was infused intravenously over a period of 20 min using a randomized crossover design with an interval of at least 5 days between the two trials. Twenty minutes after administration of the drug, 250 micrograms ACTH was injected. Plasma cortisol was measured prior to stimulation of the adrenal cortex and 30, 60 and 120 min afterwards; levels of aldosterone and 11-desoxy-cortisol were determined after 60 min. Standard radioimmunoassays were used. Haemodynamic parameters were measured non-invasively. RESULTS. In contrast to the placebo, enoximone resulted in a significant (P < 0.01) increase in the cardiac index (from 3.2 +/- 0.7 to 3.9 +/- 0.9 l min-1 m-2) and heart rate (from 69 +/- 11 to 81 +/- 8 min-1) and a decrease in peripheral resistance (from 1120 +/- 202 to 894 +/- 183 dyn s cm-5); blood pressure fell only slightly. Following injection of ACTH there were significant increases in cortisol (from 63 +/- 29 to 274 +/- 58 micrograms/l), aldosterone (from 86 +/- 37 to 300 +/- 105 ng/l) (both P < 0.001) and 11-desoxycortisol (from 5.3 +/- 1.2 to 9.8 +/- 4.6 micrograms/l; P < 0.05). There was no difference between enoximone and placebo at any time (P > 0.2). CONCLUSIONS. This study confirms the inodilation caused by enoximone. The normal response to ACTH rules out a direct inhibitory effect of a loading dose of 1.25 mg enoximone on the adrenal cortex. As the concentration of the major metabolite of enoximone, the sulphoxide, has been shown to surmount that of the parent drug after 40 min, this also holds true for the metabolite. We conclude that in contrast to etomidate, which causes a substantial reversible adrenal suppression after a single dose of 0.2 mg/kg, enoximone 1.25 mg/kg did not interfere with corticosteroid synthesis or release. Taking into account the metabolism and pharmacokinetics of this inodilator, there is no reason to expect an inhibitory effect even after repeated dosage.

Adrenal Cortex↗
PubMed1991

Structural requirements of the cytoplasmic domains of the human macrophage Fc gamma receptor IIa and B cell Fc gamma receptor IIb2 for the endocytosis of immune complexes.

Two isotypes of the monocyte/macrophage as well as B cell Fc gamma receptor type II (FcRIIa and FcRIIb2, respectively) mainly differ in the length (76 vs. 44 amino acids) and amino acid sequence of their cytoplasmic domains. Only the eight amino acids just behind the putative transmembrane region are identical. Despite this marked difference, both FcRII mediate endocytosis of immune complexes. To determine the functional significance of the cytoplasmic domains, we expressed truncated FcRIIa and FcRIIb2 in FcR- BHK-21 cells. Mutants of both receptors containing only one amino acid (tail-minus) of the cytoplasmic domain failed to mediate immune complex uptake. The significance of the cytoplasmic domain of the receptors could be further demonstrated using a chimeric FcRIII-FcRIIa construct. Therefore we expressed an FcRIII lacking the hydrophobic carboxyl terminus (containing the putative phosphatidyl - inositol - glycan anchor site) fused inframe to the transmembrane and cytoplasmic domain of the FcRIIa in BHK-21 cells. In contrast to the wild type FcRIII, this chimeric receptor mediated immune complex uptake indistinguishable from that mediated by the FcRIIa. Receptor mutants with relatively short cytoplasmic domains (FcRIIb2: 13, and FcRIIa: 16 amino acids) revealed, that these short amino acid stretches are sufficient to allow reduced receptor-mediated endocytosis of bound ligand. Furthermore, using FcRIIa deletion mutants with a cytoplasmic domain consisting of 62, 46, and 28 amino acids, respectively, we found that the capability of these mutants to mediate immune complex uptake decreased gradually with the truncation of the cytoplasmic tails. Thus, only short amino acid sequences of the cytoplasmic domain are sufficient to enable an, albeit reduced, receptor-mediated endocytosis.

Animals↗
PubMed1991

[Diagnosis of malignant hyperthermia. The platelet test versus the in vitro contracture test].

An eight-year-old boy was scheduled for an orthopaedic operation with a clinically abortive reaction of malignant hyperthermia and a positive platelet test result. Since there has been no validation for this platelet test, we performed a muscle biopsy and the caffeine- halothane-contracture test (CHCT). The young patient was found to be negative (MHN) in CHCT. Furthermore, the valence and the validity of the used platelet test are discussed for diagnostic purposes. With regard to resulting consequences, first of all in respect of possibly false negative results, we suggest to investigate all patients classified by this platelet test with the accepted and established CHCT.

Blood Platelets↗
PubMed1991

[Risks and side effects of intraoperative autotransfusion].

At the Institute of Anesthesiology of the University of Würzburg, blood has routinely been replaced by autotransfusion in orthopedic and surgical patients since the mid-seventies. At present the Haemonetics-Cell-Saver 3 is used to prepare autologous erythrocyte concentrates. When using this or similar, older, autotransfusion machines, the most dangerous hazard is venous air embolism during manual use despite blood centrifugation and preparation. To avoid this danger, the connecting tube to the patient must be clamped during filling of the autotransfusion bag. During autotransfusion the connecting tube between blood centrifuge and retransfusion bag must be clamped. The time loss due to this management has to be accepted. Regarding coagulation disorders, autotransfusion of large amounts of blood resembles massive transfusion with homologous blood. To maintain coagulation, hemostaseological parameters (Quick, thrombin time, ATIII) should be analyzed at the latest after replacement of half the estimated blood volume. On principle, blood components should be substituted only according to measured values. The substitution of ATIII is most frequently necessary to decrease the hazard of vein thrombosis and pulmonary embolism in these patients. The hazard of blood contamination by suctioning of operating room air should be considered. The number of operating room personnel should be as low as possible. Additionally, the suction device could be constructed to function only when necessary and not continuously. When these safety measures are followed, risks of this effective blood-saving procedure are minimized.

Blood Coagulation Tests↗
PubMed1991

Endocytosis of human IgG:Fc receptor complexes by transfected BHK cells.

We have analyzed the mode of uptake of human beta FcRII molecules expressed in BHK cells (clone 2/14). When challenged with aggregated human IgG (ahIgG), these cells bind the ligand at 4 degrees C and endocytose the IgG: receptor complexes rapidly upon warming to 37 degrees C, as seen by fluorescence microscopy with antibodies directed against human IgG. Using 125I-labeled ahIgG, we found that 40% of the bound ligand was internalized within 15 min, and approximately 60% within 2 h. Surface replication and thin sectioning combined with immunogold labeling revealed that the ligand was taken up by coated vesicles and was transferred to the endosomal/lysosomal compartment. This was confirmed by confocal laser microscopy of cells double labeled for clathrin and ahIgG. After modulation of the coated vesicle pattern by hypertonic medium, ahIgG transport was impaired. These data show that a single isoform of human FcRII, expressed in an animal cell negative for Fc receptors, can use the coated vesicle based endocytic pathway of the host cell. Reincubation of cycloheximide-treated cells with a second batch of ligand showed that approximately 20% of the beta FcRII was recycled. This finding is in apparent contrast to the fate of the endogenous Fc receptors expressed on mouse macrophages.

Animals↗
PubMed1990

Distribution, inducibility and biological function of the cloned and expressed human beta Fc receptor II.

A cDNA encoding the human beta Fc gamma receptor II (FcRII) was isolated from a placental cDNA library. Analysis of the predicted amino acid sequence indicates that this receptor is synthesized with a 42-amino acid leader sequence. The mature protein consists of 249 amino acids. The leader sequence and the cytoplasmic domain are strikingly different from the CDw32 antigen but show great homology to the mouse beta 2FcR. RNA blot analysis of human cells using CDw32 and beta FcRII-specific DNA fragments demonstrated one beta FcRII transcript (1.7 kb) in B cells and in HL-60 cells which were induced to differentiate along a monocyte-macrophage pathway by phorbol 12-myristate 13-acetate treatment. Under these conditions the CDw32 transcripts (2.5 and 1.7 kb) are induced to a minor extent in HL-60 cells. In contrast, the 2.5-kb CDw32 transcript is strongly induced in HL-60 cells which have been induced to differentiate into granulocytes by exposure to dimethylsulfoxide. To determine the biological properties of the beta FcRII, we expressed the antigen in FcR- hamster cells. Only immune complexes but not monomeric human IgG were bound significantly. Bound ligand was efficiently internalized within 15 min and it was then found in vesicular structures. Thus the low-affinity beta FcRII is able to internalize ligands without cooperation with any other FcR.

Amino Acid Sequence↗
PubMed1990

Organization of human FcRII and FcRII-like (beta FcRII) genes: structural homology to HLA class I and class II genes.

Genomic EMBL 3 DNA clones representing part of the human Fc gamma receptor II and the beta Fc gamma receptor II genes were characterized. One of them contains the first five exons including the 5' flanking region of the beta FcRII gene. The signal peptide, the extracellular domains, the putative membrane spanning region, and the first amino acids of the cytoplasmic region encoded by these five exons are spread over approximately 11 kb. Another genomic DNA clone comprises four exons encoding the second extracellular domain and the transmembrane and cytoplasmic regions of the FcRII. Alignment of the genomic DNA clones reveals that these FcR genes are identically organized. Comparison of the corresponding regions of these clones shows that not only the exons are strikingly homologous but also the splice junctions and parts of the intervening sequences are conserved. Furthermore, the genomic organization of FcRII and HLA-class I resemble each other.

Antigens, Differentiation↗
PubMed1990

New site for pacemaker generators in children.

Bipolar pacemaker implantation was performed in three children, aged 5, 6 and 9 years. The two epimyocardial fishhook pacing electrodes were inserted through different incisions. After resection of the anterior part of the 5th and 6th rib, the generator was placed into a pocket with the posterior wall resulting from the remaining periostium/perichondrium and the anterior wall consisting of the isolated intercostal and pectoral muscle. The leads were brought in extrapleurally and connected to the generator. The operations were conducted without perioperative and late postoperative complications.

Child↗
PubMed1990

Transient transcatheter balloon closure of patent foramen ovale following surgical repair of critical pulmonary stenosis.

Severe cyanosis resulting from postoperative atrial right-to-left shunt is a life-threatening complication. We present a technique of transient transcatheter balloon closure of a patent foramen ovale in a newborn operated on for critical pulmonary stenosis, where the foramen ovale had been left open intraoperatively. Cardiac catheterization was performed under echocardiographic control in the intensive care unit and the foramen ovale was occluded with a water-filled balloon-catheter. Significant improvement of arterial oxygen tension allowed delayed definitive surgical closure in a second step. Unfortunately, the child developed right-sided pneumothorax postoperatively and died of cardiopulmonary failure. Nevertheless, this procedure seems a suitable way to relieve atrial right-to-left shunt temporarily until definitive surgical closure can be performed.

Anastomosis, Surgical↗
PubMed1990

[Coronary aneurysm following Kawasaki syndrome].

In 10 boys with coronary aneurysms following Kawasaki syndrome echocardiography was performed and compared to angiography with respect to its reliability in detecting coronary aneurysms. All patients had central aneurysms of the left coronary artery which were visualized by echocardiography. In contrast, only two of six central aneurysms of the right coronary artery were detected echocardiographically. None of four leftsided and five rightsided peripheral coronary aneurysms were seen by echocardiography. There was no correlation between severity of coronary lesions and the score of Asai and Kusakawa estimating the risk of aneurysms on clinical grounds. Regression of coronary aneurysms was observed in seven, persistence in two, and progression in one patient, respectively, within 7-27 months. All children are doing well without clinical evidence of myocardial ischemia. We conclude from our experience that involvement of coronary arteries is unlikely if the central parts of the left coronary artery, which can be well visualized by echocardiography, are inconspicuous. In case echocardiography suggests a coronary aneurysm we recommend angiographic investigation in order to visualize the peripheral coronary arteries.

Aspirin↗
PubMed1989

[Pulmonary segmental artery angiography in intensive care patients].

The indication for wedge angiograms in intensive-care patients within the scope of X-ray chest examination is outlined. The obligatory wedge angiogram in patients with Swan-Ganz catheter is redundant. 4 indications for this special examination are specified. As a new possibility for differentiating between the ventral or dorsal course of pulmonary vessels, an inverse ratio of arborization angles is outlined for the first time.

Catheterization, Swan-Ganz↗