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M Vogel

Publications and source records attributed to M Vogel.

At least 91 records · Page 5Linked to original sources
PubMed2000

Hydrolysis of low-molecular-weight oligosaccharides and oligosaccharide alditols by pig intestinal sucrase/isomaltase and glucosidase/maltase.

The ability of purified pig intestinal sucrase/isomaltase (SI; EC 3.2.1.10/48) and glucosidase/maltase (GM; EC 3.2.1.20) to hydrolyze di- and oligosaccharides consisting of D-glucose and D-fructose residues and the corresponding alditols was studied. The products, after incubation, reflect different binding patterns at both catalytic sites of SI. The active site of the sucrase subunit cleaves alpha,beta-(1-->2) glycosidic bonds, and only two monomer units of the substrates bind with favorable affinity. Oligosaccharides and reduced oligosaccharides containing alpha-(1--6) and alpha-(1-->1) glycosidic bonds are hydrolyzed by isomaltase, and for the active site of this subunit more than two subsites were postulated. Moreover, different binding sites for various aglycons seem to exist for isomaltase. Oligosaccharide alcohols are cleaved at lower rates if the reduced sugar residue occupies the aglycon binding site. GM also hydrolyzes alpha-(1-->1) linkages, but at a lower rate. The enzyme has the ability to bind compounds containing residues other than D-glucose. There are indications for similarities between GM and the isomaltase subunit of SI in the binding mode of oligosaccharides.

Animals↗
PubMed2000

Mimicry of human IgE epitopes by anti-idiotypic antibodies.

According to Jerne's network hypothesis, the binding site of an anti-idiotypic antibody also represents the internal image of an epitope present on a foreign, or even a self antigen. In recent years, antigen mimicry has been defined at the molecular level for some xeno-antigens. However, until now there has been no demonstration of structural mimicry between a human anti-idiotypic antibody and a self structure. To address this question, we used human IgE as the self structure and a well-defined anti-human IgE mAb (BSW17). We describe the isolation of two anti- idiotypic antibodies specific for the anti-IgE antibody BSW17 from a non-immune human Fab phage display library. Interestingly, these two anti-idiotypic antibodies mimic the same molecular surface region as a previously described IgE peptide mimotope isolated by panning on BSW17, but they cover a much larger epitope on the IgE molecule. Accordingly, immunisation of rabbits with the two anti-idiotypic antibodies induced high-affinity antibodies with the same characteristics as BSW17. Thus, our data demonstrate that it is possible to isolate anti-idiotypic antibodies derived from the human genome without the need for hyperimmunization, and confirm Jerne's hypothesis that both foreign antigens and self structures can be mimicked by our own immunoglobulins.

Amino Acid Sequence↗
PubMed2000

Renal function after cardiopulmonary bypass surgery in cyanotic congenital heart disease.

UNLABELLED: We studied perioperative renal damage in 22 patients with long-standing cyanotic congenital heart disease. BACKGROUND: [corrected] Postoperative acute renal failure is a major complication of cardiac surgery associated with poor prognosis. Our study was designed to identify risk factors for renal failure in patients with cyanotic congenital heart disease. PATIENTS: 22 cyanotic patients with a oxygen saturation of 82% (38-92%), age 14 years (5-42 years) and six controls with atrial septal defect, age 37 years (28-66 years) were investigated with repeated urinary analyses. RESULTS: Before operation, six of 22 of the cyanotic patients had albuminuria. Postoperatively three patients developed acute renal failure including glomerular and tubular damage. Urinary albumin analysis >1000 mg g(-1) creatinine after 24 h and N-acteyl-beta-D-glucosaminidase analysis >100 U g(-1) creatinine after 48 h predicted dialysis requirement. In noncyanotic controls only one preoperative and none of the postoperative analyses were pathological. CONCLUSIONS: Patients with cyanotic congenital heart disease are at risk for acute renal failure, which can be prognosed by urine analysis already 24 h after surgery. Cyanotic glomerulopathy should be known before surgery. To lower the risk, cardiopulmonary bypass time should be kept as short as possible and adequate hydration should be maintained in combination with extended diuretic therapy.

Acetylglucosaminidase↗
PubMed2000

[Severe complications caused by inattention to endocarditis prevention during dental procedures in adults with congenital heart abnormalities].

BACKGROUND AND OBJECTIVE: Despite new guidelines on antibiotic prophylaxis to prevent bacterial endocarditis there is still confusion about the forms of dental procedures requiring antibiotic prophylaxis. Aim of this study was to determine the incidence of bacterial endocarditis following dental procedures in adults with congenital heart disease during a one-year period, and to assess connections with prophylaxis. PATIENTS AND METHODS: The case notes of all adults with congenital heart disease (CHD) treated in hospital during a one year period were analyzed retrospectively to identify cases of endocarditis, and all adults with CHD admitted to hospital for other reasons than endocarditis were interviewed about their knowledge of antibiotic prophylaxis against bacterial endocarditis. RESULTS: Among the 456 adults with CHD 351 (78%) knew about the need for antibiotic prophylaxis against bacterial endocarditis. Three patients developed endocarditis, in each case after a visit to the dentist. The disease started 11-16 days after dental descaling had been performed without antibiotic covering, one patient developing a brain abscess. The patients had to be treated in the hospital for 42-49 days. Despite presentation by the patient of a leaflet with recommendations for prophylaxis, the dentist refused to give antibiotics. CONCLUSIONS: Knowledge of adults with CHD is satisfactory but can still be improved. Even more important is better training of dentists who treat patients with CHD with special emphasis on the specific procedures including dental descaling, which require antibiotic prophylaxis.

Adolescent↗
PubMed2000

Thermal unbinding of highly oriented phospholipid membranes.

We present a temperature dependent x-ray reflectivity study of highly oriented, fully hydrated multilamellar phospholipid membranes. Both the specular and diffuse (nonspecular) x-ray reflectivity were measured for dimyristoyl-sn-glycero-phosphocholine (DMPC) and oleoyl-palmitoyl-sn-glycero-phosphocholine (POPC) on silicon substrates in excess water. In this configuration the repeat distance as well as the fluctuation spectra can be determined as a function of temperature. Both model systems studied exhibit a discontinuous unbinding transition from a substrate bound, multilamellar state to a state of freely dispersed bilayers in water. In the unbound phase a single membrane remains on the substrate.

Dimyristoylphosphatidylcholine↗
PubMed2000

Pathologic correlation of sonographic echogenic foci in the fetal heart.

The goal of the current paper is to present, on the basis of six investigated fetal hearts, the pathological substrate of prenatally, sonographically diagnosed echogenic intramyocardial foci. The right ventricle, left ventricle, interventricular septum and papillary muscles of both ventricles of six hearts of the fetuses of high-risk pregnant women showing sonographically diagnosed intramyocardial echogenic foci were investigated. At termination of pregnancy all the women were between the 20th and the 24th week of gestation. Of the six cases, four were induced abortions and two were spontaneous abortions. For the control group we investigated the hearts of two fetuses without heart defects at the 22nd and 23rd week of gestation which had proven extracardial anomalies and a normal karyotype. Both cases were induced abortions which prenatally showed no echogenic cardiac foci. In all eight cases a prenatal karyotyping was performed. In the six cases with echogenic foci the location and number of the foci were determined both prenatally and by means of histologic sections; the size of the foci was measured as well. Histological staining was with routine haematoxylin-eosin; Masson-Goldner was used for connective tissue; Kossa for calcification; and Berlin blue for haemosiderin. Histologically, in all six cases, intramyocardial calcifications surrounded by fibrotic tissue were in: papillary muscle of the left ventricle in six cases; papillary muscle of the right ventricle in one case; and the subendocardial myocardium of the right ventricle in one case. Four cases had one, one case had two and one case had three calcified foci. Three cases had cardiac and two cases had extracardiac anomalies. Four cases had chromosome anomalies: two were trisomy 21, one trisomy 13 and one triploidy. The remaining two cases had a normal karyotype. No case showed pathological changes of the chordae tendinae, myocardial cell necrosis or inflammation. There were no patho-morphological differences between the intramyocardial calcifications of the papillary muscles in cases with chromosome anomalies and with normal karyotype. As the patho-morphological correlate of the sonographically diagnosed echogenic foci, histological investigation on all six fetal hearts showed coarse intramyocardial calcifications surrounded by myocardial fibrosis. Conventional histological methods gave no indication of the cause of the intramyocardial calcifications.

Abortion, Induced↗
PubMed2000

Applications of hyphenated LC-MS techniques in pharmaceutical analysis.

In pharmaceutical analysis, ie the analytical development and quality control of drug substances and dosage forms, mass spectrometry (MS) combined with chromatographic separation is perhaps the most powerful technique for the monitoring, characterization and identification of impurities. The addition of further dimensions to chromatographic separations by hyphenated techniques offers unique possibilities of efficiently supporting pharmaceutical development and ensuring the quality and safety of pharmaceuticals. However, the ionization process in MS involves some characteristics which have to be recognized and taken into account for an appropriate application as well as the evaluation of the results. Chromatographic method development and validation can be supported very effectively by MS detection, eg in the investigation of coelution and peak purity. Chiral amino acid analysis is largely facilitated by the mass-specific detection of the derivatized amino acid enantiomers, which ignores all other interfering substance peaks. Examples are presented for the use of LC-MS-MS fragmentation and high-resolution MS in the structural elucidation of degradation products and impurities. LC-MS is systematically applied to monitor impurity profiles during pharmaceutical development and scaling up and supports the safety evaluation of batches used in clinical studies.

Amino Acids↗
PubMed2000

Oral anti-IgE immunization with epitope-displaying phage.

An essential requirement for oral vaccines is the ability to survive the harsh environment of the stomach in an antigenically intact form. As bacteriophages are adapted to this environment we used epitope-displaying M13 bacteriophages as carriers for an experimental oral anti-IgE vaccine. The feasibility of this approach was tested in a simulated gastric fluid using two different mimotopes as well as an anti-idiotypic Fab of the non-anaphylactogenic monoclonal anti-IgE antibody BSW17. All phage clones remained infective after this treatment. However, only epitopes displayed on the pVIII protein were still recognized by BSW17 whereas pIII-expressed epitopes were rapidly inactivated. Surprisingly, when used for oral immunization of mice all phage clones induced anti-IgE antibodies. In contrast, oral immunization with the purified, pVIII protein displaying the mimotope induced anti-phage but no anti-IgE antibodies. After feeding a single dose of mimotope-displaying bacteriophage, phage DNA could be detected in mouse feces for 10 days. Our results show that epitope-displaying bacteriophages can be used to induce an epitope-specific antibody response via the oral route.

Administration, Oral↗
PubMed2000

Effects of various types of molecular dynamics on 1D and 2D (2)H NMR studied by random walk simulations

By carrying out random walk simulations we systematically study the effects of various types of complex molecular dynamics on (2)H NMR experiments in solids. More precisely, we calculate one-dimensional (1D) (2)H NMR spectra and the results of two dimensional (2D) (2)H NMR experiments in time domain, taking into account isotropic as well as highly restricted motions which involve rotational jumps about different finite angles. Although the dynamical models are chosen to mimic the primary and secondary relaxation in supercooled liquids and glasses, we do not intend to describe experimental results quantitatively but rather to show general effects appearing for complex reorientations. We carefully investigate whether 2D (2)H NMR in time domain, which was originally designed to measure correlation times of ultraslow motions (tau >/= 1 ms), can be used to obtain shorter tau, too. It is demonstrated that an extension of the time window to tau >/= 10 &mgr;s is possible when dealing with exponential relaxation, but that it will fail if there is a distribution of correlation times G(lgtau). Vice versa, we show that 1D (2)H NMR spectra, usually recorded to look at dynamics with tau in the microsecond regime, are also applicable for studying ultraslow motions provided that the loss of correlation is achieved step by step. Therefore, it is useful to carry out 1D and 2D NMR experiments simultaneously in order to reveal the mechanism of complex molecular motions. In addition, we demonstrate that highly restricted dynamics can be clearly observed in 1D spectra and in 2D NMR in time domain if long solid-echo delays and large evolution times are applied, respectively. Finally, unexpected observations are described which appear in the latter experiment when considering very broad distributions G(lgtau). Because of these effects, time scale and geometry of a considered motion cannot be extracted from a straightforward analysis of experimental results. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Acute hemodynamic effects of post cardiotomy peritoneal dialysis in neonates and infants.

OBJECTIVE: Evaluation of the acute hemodynamic changes during peritoneal dialysis in patients with low cardiac output syndrome and acute renal failure after open heart surgery. PATIENTS: Three newborns and three infants after corrective surgery of congenital heart disease with post cardiotomy dialysis. Five of these had an open thorax during dialysis. METHODS: Cardiac output measurements using the thermodilution technique on two consecutive days at four different times during the peritoneal dialysis cycle. RESULTS: We did not find a deterioration of the cardiac index or systemic vascular resistance measured over two cycles in each of the six patients. Pulmonary artery pressure rose slightly after instillation of the dialysate solution in all patients. Changes in central venous pressure and left atrial pressure were not clinically meaningful. In all patients fluid removal by peritoneal dialysis was effective. All five surviving patients recovered renal function. CONCLUSIONS: Peritoneal dialysis can be performed in newborns and infants following cardiac surgery without causing acute hemodynamic imbalances. An open chest may have a significant impact on hemodynamic stability during peritoneal dialysis by blunting any possible negative alterations of increased intraabdominal pressure.

Acute Kidney Injury↗
PubMed2000

Hydrazine reagents as derivatizing agents in environmental analysis--a critical review.

Hydrazine reagents are a well-known group of derivatizing agents for the determination of aldehydes and ketones in liquid and gaseous samples. Within this article, the most important hydrazine reagents are critically summarized, and their major applications in different fields, including environmental analysis, food chemistry and industrial analysis are introduced. As 2,4-dinitrophenylhydrazine (DNPH) is the basic reagent for several international standard procedures, its properties are discussed in detail. Particular focus is directed on the chemistry of the hydrazine reagents, and chemical interferences are considered. Recent methods for the determination of various oxidants using hydrazine reagents are presented as well. Due to limited space, this review does not cover the related field of carbohydrate analysis, although many chemical aspects are similar.

Aldehydes↗
PubMed2000

[Autopsy of the fetus. Proposed investigatory strategy as a decision aid in the autopsy of fetues with special conditions].

Prenatal examination of fetuses can now yield excellent findings and, by means of Doppler technology, can also reveal functional changes. Despite progress in fetal diagnostics, quality control of prenatal diagnoses remains necessary since prenatal findings can be the basis for deciding whether to perform preterm abortion. This is possible only by autopsy, and therefore increasing demands for precision are being placed on autoptic procedures. This is particularly the case in malformations, which can be associated with a specific syndrome and then become decisive in the context of family counseling of the parents in question. The pathologist must therefore go beyond the requirements of a standard autopsy in order to obtain thorough findings with respect to the fetus and the placenta. We describe an examination strategy for the stepwise elucidation of special and rare fetal conditions the autopsy of fetuses that is intended to provide support in decision making.

Autopsy↗
PubMed2000

[Autopsy techniques in congenital heart defects. Influence of prenatal diagnosis on the planning and carrying out of autopsies].

As a result of the quality of prenatal ultrasound and the expanded experience of prenatal diagnosticians, it is possible to observe congenital heart malformations in increasingly greater detail and at an ever earlier stage of gestation [4]. Since it is on the basis of ultrasound findings that decisions to terminate pregnancies are made, it is of cardinal importance that after termination monitoring and confirmation of the prenatal diagnosis be carried out. This need can only be adequately met by autopsy. There are different methods for carrying out autopsies when there is suspicion of a congenital heart defect: a) the Anderson sequential segmental analysis as modified according to the Berlin method; b) use of a special autoptic method corresponding to the ultrasound findings, based on defining a preferred sectional plane; c) stereomicroscopically; or d) microscopically after embedding and preparation of serial microscopic sections. For the pathologist the consequence is that he has to adapt his autopsy method to the ultrasound findings and the age of the fetus. This enables him to determine an optimal, case-based autopsy strategy for each type of cardiac defect, which is essential for monitoring of the prenatal diagnosis. The present paper discusses the various autoptic methods used in cases of congenital heart malformations and the consequences for the pathologist of the continuing improvements in prenatal diagnostics.

Autopsy↗
PubMed2000

[Combined glaucoma and cataract operation with foldable posterior chamber lens implantation. Long-term outcome and complications].

BACKGROUND: Glaucoma patients who need filtering surgery very often have cataracts as well. Combined glaucoma/cataract surgery entails a higher rate of complications and may endanger the results of glaucoma surgery. PATIENTS AND METHODS: This retrospective study investigated 223 eyes in 169 patients with uncontrolled glaucoma and cataracts. Each eye received filtering surgery and simultaneous phacoemulsification with implantation of a foldable posterior chamber lens. Mean follow-up was 32.5 months (6-57). RESULTS: Mean intraocular pressure was lowered from 24.6 +/- 6.2 to 16.4 +/- 3.4 mmHg (P > 0.0001). Visual acuity improved from 0.25 (0.01-0.5) to 0.5 (0.01-1.0). Preoperatively the mean number of medications was 2.4 (1-6) and postoperatively 1.3 (1 or 2). The most common perioperative complications were choroidal detachment (20.2%) and fibrin reaction in 10.1%; those occurring later than 4 weeks postoperatively were posterior capsule opacification requiring YAG laser capsulotomy (11.5%) and scarring of filtering bleb (7.7%). CONCLUSION: Complications encountered in the combined procedure were due mainly due to cataract surgery of glaucomatous eyes with narrow pupils and posterior synechiae. A shallow anterior chamber occurred in only one case. Despite complications the success rate in lowering intraocular pressure was comparable to that observed in filtering surgery alone.

Aged↗
PubMed2000

[Interventional occlusion of atrial septum defects larter than 20 mm in diameter].

UNLABELLED: Over the last few years, various devices for the interventional closure of atrial septal defects (ASD) up to a diameter of 20 mm have been developed. We report our clinical experience in closing ASD with a diameter larger than 20 mm diameter with the Amplatzer Septal Occluder (ASO). METHOD: The stretched diameter of the ASD was measured by inflating a sizing balloon within the defect until an indentation in the circumference in the balloon could be observed. An ASO with a stent diameter 2-4 mm larger than the indentation in the circumference of the balloon was chosen and implanted via 9-12 French sheaths. In contrast to the closure of smaller defects, pullback of the device onto the atrial septum was only performed when the connecting stent of the ASO was completely deployed in order to achieve maximal centering characteristics and optimal support of the retention skirt of the left atrial disc on the edges of the defect. Only then was the right atrial disc deployed and actively configured by advancing the sheath and the delivery cable against the atrial septum. Implantation was only attempted if the atrial septal rims (except the anterior rim around the aorta) measured more than 7 mm by echocardiography to avoid injury or disturbance of sensitive intracardiac structures. After placement, the fixation of the device and the mechanical stability was proven by an extensive "Minnesota wiggle". The ASO was released only when TEE showed no or a trivial residual color flow through the connecting stent; otherwise repositioning was performed. RESULTS: Out of 352 patients (P) with successful closure of interatrial defects, 70 P (age: 1.1-77.3 years) had stretched defects larger than 20 mm diameter (median 22 mm diameter (20-36), 25/75% quartiles = 20/26 mm). Mean shunt size was Qp:Qs 2.1:1 (0.7-3.9:1), mean fluoroscopy time 10.9 min (0-63). Complete closure could be achieved in 85.7/93.1/100% after 3 months, 1 and 2 years, respectively. Besides 3 P with persistent atrial fibrillation, only 5 P showed transient atrial tachyarrhythmias, 2 only periprocedural and 3 within the first 3 months after implantation were treated with beta-blocker. In one patient, an acute embolization of the device occurred because a diminished posterior rim was not visualized by a monoplane TEE probe necessitating surgical explantation and defect occlusion. Despite oversizing the device, no "mushrooming" misconfiguration were observed. CONCLUSION: Transcatheter closure of large atrial septal defects with the Amplatzer Septal Occluder is feasible, safe and effective. Risk of complications do not seem to occur more frequently than after closure of smaller defects if one adheres to certain sizing and implantation measures. The incidence of transient atrial tachyarrhythmias seems to be low.

Adolescent↗
PubMed2000

New osmotically active hydrogel expander for enlargement of the contracted anophthalmic socket.

BACKGROUND: Clinical anophthalmia is characterized by the absence of an eyeball within the orbit and can result in overall growth retardation of the facial skeleton. The goal of treatment consists of fitting a serial prosthesis following rapid expansion of the contracted socket as soon as possible to achieve cosmetically acceptable eyelid and orbital symmetry. METHODS: Four children, aged 3-11 months, were treated by implantation of an anhydrous, highly hydrophilic tissue expander into the rudimentary conjunctival sac. With hydration of up to 98% in 72 h, the copolymer of methylmethacrylate and vinylpyrrolidone acts like an osmotically self-inducing socket expander. RESULTS: In the course of 2 months the previous contracted socket was enlarged, the horizontal lid length increased and the hydrated expander could be exchanged for a custom-made glass prosthesis. CONCLUSION: Preliminary results suggest that this new device can be used to avoid early plastic surgery of the eyelid. In addition, it also may enlarge the volume of the bony orbit.

Anophthalmos↗
PubMed2000

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements.

A new transducer, using the effect of frustrated total internal reflection of electromagnetic waves, was developed for displacement and force measurements in muscle research. The physical theory for this effect predicts the formation of an evanescent electromagnetic field in the gap between two separated optical surfaces. This evanescent electromagnetic field enables the transmission of light across the gap between the two media, an effect not contained in ray optics formalism. In the apparatus described here, the optical surfaces were obtained by bevelling 2 optical fibres to angles higher than the specific critical angle of the media used. Since the amount of transmitted light depends strongly on the distance between the surfaces, very small forces are detectable if one fibre is used as a cantilever. To test the transducer a small myofibrillar bundle (20 microm diameter) was mounted isometrically on it and contraction activated by release of "caged" Ca2+. Force and displacement steps of 180-220 nN and 9-11 nm respectively were measured with resolutions of 10 nN and 288 pm, respectively. From theoretical and practical considerations, it is expected that the presented principle will be able to achieve even much higher sensitivity for the determination of force (better than picoNewton) and distance (femtometre).

Animals↗