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Biomedical subjects

B Schmitz

Publications and source records attributed to B Schmitz.

At least 127 records · Page 7Linked to original sources
PubMed1995

Influence of cytokine stimulation (granulocyte macrophage-colony stimulating factor, interleukin-3 and transforming growth factor-beta-1) on adhesion molecule expression in normal human bone marrow fibroblasts.

Interactions between stromal cells or extracellular matrix and hematopoietic cells are important factors for the very complex processes associated with differentiation and maturation in the bone marrow. To elucidate these multifold processes, the expression pattern of various adhesion molecules was studied on enriched fibroblastic populations derived from healthy volunteers. CD44 (homing cell adhesion molecule) and very late activation antigen beta 1 (VLA beta 1; CD29) could be demonstrated on almost all fibroblasts without an alteration following cytokine stimulation. On the other hand, VLA-2 (CDw49b), VLA-3 (CDw49c), VLA-4 (CDw49d), VLA-5 (CDw49e), intercellular adhesion molecule-1 (ICAM-1; CD54) and vascular cell adhesion molecule-1 (VCAM-1; CD106) were only represented by certain cell fractions. In our studies recombinant human granulocyte macrophage-colony stimulating factor failed to alter the expression pattern of these adhesion molecules, whereas recombinant human interleukin-3 (rhIL-3 showed a tendency for downregulation of the VLA antigens except for VLA beta 1. However, recombinant human transforming growth factor-beta 1 (rhTGF beta 1) exerted a reducing effect on the expression of VLA-3 and induced an increase in the VLA-5-positive fraction. In the immunoglobin class VCAM-1 revealed a decrease staining capacity after stimulation with rhTGF beta 1 and rhIL-3. Contrary to this finding, the presentation of ICAM-1 increased after administration of these mediators.

Bone Marrow↗
PubMed1995

CD34+ human hemopoietic progenitor cells of the bone marrow differ from those of the peripheral blood: an immunocytochemical and morphometric study.

CD34+ progenitor cells were harvested from bone marrow and peripheral blood from 10 healthy donors by immunomagnetic isolation and enrichment procedures. The CD34+ cell population was investigated using a battery of enzyme reactions and monoclonal antibodies on cytospin preparations. Additionally, morphometric measurements were carried out and also liquid suspension culture studies were performed to ascertain vitality and stem cell character. More than 95% of the total yield of medullary CD34 progenitors expressed CD45 (LCA), CD43 (MT1) and beta-glucuronidase. Reactivity with CD33 (My9), CD15 (LeuM1), CD38 (Leu17), CD20 (L26) and Ret40f (glycophorin C) was assumed to be in keeping with a transition into more differentiated elements of the various hemopoietic lineages. Morphometric analysis revealed conspicuous heterogeneity of the CD34+ cell population considering size measurements. This finding was in line with the diversities of antigen expression, indicating the more committed nature of CD34+ stem cells derived from the bone marrow in comparison with those progenitors isolated from the peripheral blood. Moreover, proliferation marker staining by PCNA disclosed a positivity in a considerable number of progenitors in contrast to the findings in CD34+ cells that are found in the peripheral blood.

Antibodies, Monoclonal↗
PubMed1995

Brain perfusion abnormalities in Gilles de la Tourette's syndrome.

BACKGROUND: Functional brain imaging with technetium-99m d,l-hexamethyl propyleneamine oxime (HMPAO) Single Photon Emission Tomography (SPET) allows us to explore the cerebral pathophysiology of Gilles de la Tourette's Syndrome (GTS). METHOD: Fifty patients and 20 controls were examined. Patients were rated for tic severity and mood. Scans were analysed quantitatively using internal ratios to the occipital cortex. RESULTS: Patients different from controls on measures of relative blood flow to the left caudate, anterior cingulate cortex and the left dorsolateral prefrontal cortex. Severity of tics was related to hypoperfusion of the left caudate and cingulate and a left medial temporal region. Hypoperfusion in the left dorsolateral prefrontal region was related to mood. CONCLUSIONS: The areas found to be hypoperfused in this study are consistent with known functions of fronto-striatal circuits. A wide range of perfusion patterns is seen, however, and no characteristic patterns for behavioural subgroups has been documented with this technique.

Adolescent↗
PubMed1994

The L2/HNK-1 carbohydrate is carried by the myelin associated glycoprotein and sulphated glucuronyl glycolipids in muscle but not cutaneous nerves of adult mice.

We have previously shown that myelinating Schwann cells associated with motor, but not sensory, axons in peripheral nerves of adult mice express the L2/HNK-1 carbohydrate epitope. This carbohydrate structure carried by glycolipids and neural cell adhesion molecules has been suggested to specifically foster regrowth of motor as opposed to sensory axons after infliction of a lesion. To determine which molecular components may be the carriers of the L2 carbohydrate in motor axon-associated myelinating Schwann cells, we have isolated the purely sensory, cutaneous branch and the mixed sensory and motor muscle branch of the femoral nerve of adult mice, isolated the myelin fraction thereof and analysed the molecules expressing the L2 carbohydrate by several immunochemical methods. L2 immunoreactivity in myelin of the muscle branch was four to five times higher than that of the cutaneous branch. The 110 kDa L2-immunoreactive glycoprotein in myelin of the muscle branch, which is not L2-immunoreactive in the cutaneous branch, was identified as the myelin-associated glycoprotein by a combination of immunoprecipitation and Western blot analysis. Myelin extraction with organic solvents additionally revealed the two L2-carrying glycolipids, which amounted to approximately 40 ng glycolipid/mg dry weight in myelin of the muscle branch, whereas no significant amounts of the L2 glycolipids were found in myelin of the cutaneous branch. These observations suggest an astonishing degree of differential regulation of carbohydratesynthesizing activities in myelinating Schwann cells.

Animals↗
PubMed1994

Determination of structural elements of the L2/HNK-1 carbohydrate epitope required for its function.

The L2/HNK-1 carbohydrate epitope has been shown to carry an unusual 3'-sulfoglucuronic acid linked O-glycosidically through a neolactosyl-type backbone to a ceramide residue. Using monoclonal antibodies, the same or a closely related epitope has also been detected N-glycosidically linked to glycoproteins, amongst them several neural cell adhesion molecules. We used synthetic glycolipids carrying sulfated or non-sulfated glucuronic acid attached to ceramide through glycans of different length to show that not only the sulfated glucuronic acid but also the neolactosyl-type backbone is essential for the recognition of the L2/HNK-1 carbohydrate by a monoclonal antibody, its binding to laminin and its role in neural cell migration and outgrowth of processes from neurons and astrocytes.

Animals↗
PubMed1994

Magnetic activated cell sorting (MACS)--a new immunomagnetic method for megakaryocytic cell isolation: comparison of different separation techniques.

Megakaryocytes are difficult to isolate because of their fragility, their tendency to aggregate, and their varying sizes. For purification of cells at different stages of maturation and of different sizes (ploidy classes) we developed an immunomagnetic cell sorting method (MACS) to enrich the whole spectrum of the megakaryocytic cell lineage. The use of small magnetic beads coupled to various antibodies and labelling with fluorescent antibodies allowed direct analysis of enrichment and evaluation of the isolated fraction without further staining or detachment procedures. CD 61 (Y2/51), a monoclonal antibody directed against platelet glycoprotein IIIa, was employed to perform the separation procedure. An enrichment up to 47% of CD 61-positive cells with an average of 37% and a recovery rate of 37% was obtained by using the MACS technique. Pre-enrichment by Percoll density centrifugation, followed by MACS separation, resulted in an enrichment of 65% and a recovery rate of 67%. The relative amount of small megakaryocytic cells in only MACS-enriched cell populations, however, was higher than in Percoll/MACS fractions. As a parameter of vitality we tested cytokine secretion of the enriched megakaryocytes in reverse haemolytic plaque assays. Secretion of IL-1, IL-6, GM-CSF, and PDGF with and without stimulation by phorbol myristate acetate was demonstrable at the single cell level.

Bone Marrow Cells↗
PubMed1994

Nucleotide sequence of human adenovirus type 12 DNA: comparative functional analysis.

A fresh inoculum of human adenovirus type 12 (Ad12) was obtained from the American Type Culture Collection and passaged once on human embryonic kidney cells, and Ad12 DNA was prepared from the first-passage yield to avoid higher passages which might have generated host-virus DNA recombinants. The 18 PstI fragments of Ad12 DNA were cloned into the pBluescript KS vector, and the entire nucleotide sequence of both strands from all 18 fragments was determined by using successive oligodeoxyribonucleotide primers. Ad12 DNA extends over 34,125 nucleotide pairs, and its molecular weight is calculated to be about 22 x 10(6). The nucleotide sequence of Ad12 DNA was subjected to computer analyses that determined possible open reading of frames on the two strands, the leader sequences, the position of the virus-associated RNA coding region, possible TATA, and polyadenylation signals. The distribution of the Ad12 open reading frames was similar to that in the previously sequenced Ad2 DNA, but there were also distinct differences. Ad12 DNA has an inverted terminal redundancy of 161 nucleotides, compared with 102 nucleotides in Ad2 DNA. There were stretches of sequence identity between Ad2 and Ad12 DNAs at both termini; the overall sequence similarity between the two viral genomes ranged between 59% (polypeptide IX) and 77% (in the E2 region), with high homology also in the sequences for the adenovirus DNA polymerase.

Adenoviruses, Human↗
PubMed1994

Late transcripts of adenovirus type 12 DNA are not translated in hamster cells expressing the E1 region of adenovirus type 5.

Hamster cells are completely nonpermissive for the replication of human adenovirus type 12 (Ad12), whereas types 2 and 5 can replicate in hamster cells. The Ad5-transformed hamster cell line BHK297-C131, which carries the left terminal 18.7% of the Ad5 genome and expresses at least the viral E1A region, can somehow complement Ad12 DNA replication and the transcription of the late Ad12 genes. Since the interaction of Ad12 with hamster cells must constitute a significant factor in the induction of Ad12 tumors in neonatal hamsters, we have continued to examine details of this abortive virus infection. The late Ad12 mRNAs in BHK297-C131 cells are polyadenylated but are synthesized in reduced amounts compared with the Ad12 products in Ad12-infected human cells, which are permissive for viral replication. The late mRNA derived from the Ad12 fiber gene has been assessed for its structural properties. By cloning cDNA transcripts from this region and determining their nucleotide sequences, the authenticity of the complete Ad12 fiber sequence and the completeness of the Ad12-typical tripartite leader have been confirmed. Moreover, in Ad12-infected BHK297-C131 cells the Ad12 virus-associated RNA, a virus-encoded translational activator with the correct nucleotide sequence, is synthesized. Nevertheless, the synthesis of detectable amounts of Ad12 virion-specific proteins, and in particular that of the main viral antigens, hexons and fibers, cannot be documented. Cellular factors needed to promote late mRNA translation might be missing, or inhibitory factors might exist in Ad12-infected BHK297-C131 cells.

Adenovirus E1 Proteins↗
PubMed1994

Recognition of mental state terms. Clinical findings in children with autism and a functional neuroimaging study of normal adults.

BACKGROUND: The mind's ability to think about the mind has attracted substantial research interest in cognitive science in recent decades, as 'theory of mind'. No research has attempted to identify the brain basis of this ability, probably because it involves several separate processes. As a first step, we investigated one component process-the ability to recognise mental state terms. METHOD: In Experiment 1, we tested a group of children with autism (known to have theory of mind deficits) and a control group of children with mental handicap, for their ability to recognise mental state terms in a word list. This was to test if the mental state recognition task was related to traditional theory of mind tests. In Experiment 2, we investigated if in the normal brain, recognition of mental state terms might be localised. The procedure employed single photon emission computerised tomography (SPECT) in normal adult volunteers. We tested the prediction (based on available neurological and animal lesion studies) that there would be increased activation in the orbito-frontal cortex during this task, relative to a control condition, and relative to an adjacent frontal area (frontal-polar cortex). RESULTS: In Experiment 1, the group with autism performed significantly worse than the group without autism. In Experiment 2, there was increased cerebral blood flow during the mental state recognition task in the right orbito-frontal cortex relative to the left frontal-polar region. CONCLUSIONS: This simple mental state recognition task appears to relate to theory of mind, in that both are impaired in autism. The SPECT results implicate the orbito-frontal cortex as the basis of this ability.

Adolescent↗
PubMed1994

[A meta-analysis of the effectiveness of gestalt therapy].

This metaanalytical assessment of evaluation research in the field of Gestalt therapy has been conducted on the basis of 38 studies which took place between 1970 and 1986. Its scope is substantially broader than the metaanalysis of Smith, Glass and Miller (1980) or the secondary analysis of Grawe's Berner Workgroup documented in Forschungsgutachten zu Fragen eines Psychotherapeutengesetzes (1991). The results indicate Gestalt therapy to be an effective psychotherapeutic treatment which is not inferior to other comparable methods of treatment. No definitive statement can be made concerning differential indication, individual therapy setting or long-term measures.

Gestalt Therapy↗
PubMed1994

[Preoperative evaluation of drug resistant focal epilepsies with 123I-iomazenil SPECT. Comparison with vidio/EEG monitoring and postoperative results].

SPECT with the benzodiazepine receptor antagonist 123I-Iomazenil was performed in 33 patients with intractable partial seizures for pre-operative evaluation. The results combined with MRI and 99mTc-HMPAO-SPECT findings were compared with the video-assisted EEG monitoring ("gold standard") which localised the focus in 25 patients. 11 patients underwent surgical resection of the epileptogenic area and became seizure-free for a period up to 13 months. The Iomazenil SPECT had a significantly higher sensitivity compared to 99mTc-HMPAO in the visualization of an epileptogenic area and should be regularly used in the diagnostic of medically intractable partial seizures.

Adolescent↗
PubMed1994

[123I-iomazenil- and 99mTc-HMPAO in the diagnosis of focal epilepsies: a comparison of untreated and treated patients].

The purpose of this study was to compare HMPAO- and IMZ-SPECT findings in treated and untreated patients with focal epilepsies. We examined 20 patients (untreated 13; treated 7). All patients had a normal CT and/or MRI scan. In all patients both whole-brain activity and regional count density (rcd) were evaluated by SPECT. Furthermore, the specific and non-specific binding of IMZ were calculated for each ROI and the results of both, treated and untreated patients were compared. Our data indicate that the normalized cerebral total binding of IMZ was significantly increased in all regions in the group of treated patients (p < 0.001). In contrast, no difference in the tracer binding was found with HMPAO-SPECT. We conclude that the difference in the IMZ-binding might be due either to exogenous or endogenous factors. In our study IMZ-SPECT had a higher sensitivity and a lower specificity in the detection of decreased rcd in areas with EEG findings that indicate an epileptogenic focus compared with HMPAO-SPECT.

Adolescent↗
PubMed1993

The L2/HNK-1 carbohydrate mediates adhesion of neural cells to laminin.

The L2/HNK-1 carbohydrate epitope shared by several neural adhesion molecules has been implicated in cell-to-cell and cell-to-laminin adhesion (Keilhauer et al., Nature, 316, 728-730, 1985; Künemund et al., J. Cell Biol., 106, 213-223, 1988). As demonstrated previously for chicken retinal ganglion cells (Cole et al., Neurosci. Lett., 93, 170-175, 1988), cerebral cortex astrocytes or cerebellar neurons could not be shown to adhere to the substrate-bound L2/HNK-1 carbohydrate. The cell-bound L2/HNK-1 carbohydrate, however, was a potent mediator of astrocytic and neuronal cell adhesion to laminin, which was strongly reduced in the presence of the L2/HNK-1 carbohydrate-carrying glycolipids or Fab fragments of a monoclonal antibody against it. Inhibition of adhesion could not be observed in the presence of the negatively charged gangliosides or sulphatide, but in the presence of heparin. To investigate whether the L2/HNK-1 carbohydrate and heparin use the same or different binding sites on laminin, adhesion of cells to laminin was determined in the presence of heparin and Fab fragments of a monoclonal L2 antibody, which gave an additive value of inhibition as compared to the inhibition caused by the single compounds. This result, as well as studies of the binding of the L2/HNK-1 glycolipids to laminin in the presence of heparin, indicates that the L2/HNK-1 carbohydrate and heparin are implicated in different aspects of neural cell adhesion to laminin.

Animals↗
PubMed1993

The fourth immunoglobulin-like domain of NCAM contains a carbohydrate recognition domain for oligomannosidic glycans implicated in association with L1 and neurite outgrowth.

We have previously shown that the neural adhesion molecules L1 and NCAM interact with each other to form a complex which binds more avidly to L1 than L1 to L1 alone (Kadmon, G., A. Kowitz, P. Altevogt, and M. Schachner. 1990a. J. Cell Biol. 110:193-208). This cis-association between L1 and NCAM is carbohydrate-dependent (Kadmon, G., A. Kowitz, P. Altevogt, and M. Schachner. 1990b. J. Cell Biol. 110:209-218). In the present study, we report that L1 and NCAM bind to each other via oligomannosidic carbohydrates expressed by L1, but not by NCAM, as shown in several experiments: (a) complex formation between L1 and NCAM is inhibited by a mAb to oligomannosidic carbohydrates and by the oligosaccharides themselves; (b) NCAM binds to oligomannosidic carbohydrates; (c) within the L1/NCAM complex, the oligomannosidic carbohydrates are hidden from accessibility to a mAb against oligomannosidic carbohydrates; (d) the recombinant protein fragment of NCAM containing the immunoglobulin-like domains and not the fragment containing the fibronectin type III homologous repeats binds to oligomannosidic glycans. Furthermore, the fourth immunoglobulin-like domain of NCAM shows sequence homology with carbohydrate recognition domains of animal C-type lectins and, surprisingly, also with plant lectins. A peptide comprising part of the C-type lectin consensus sequence in the fourth immunoglobulin-like domain of NCAM interferes with the association between L1 and NCAM. The functional importance of oligomannosidic glycans at the cell surface was shown for neurite outgrowth in vitro. When neurons from early postnatal mouse cerebellum were maintained on laminin or poly-L-lysine, neurite outgrowth was inhibited by oligomannosidic glycans, by glycopeptides, glycoproteins, or neoglycolipids containing oligomannosidic glycans, but not by nonrelated oligosaccharides or oligosaccharide derivates. Neurite outgrowth was also inhibited by the peptide comprising part of the C-type lectin consensus sequence in the fourth immunoglobulin-like domain of NCAM. The combined results suggest that carbohydrate-mediated cis-associations between adhesion molecules at the cell surface modulate their functional properties.

Amino Acid Sequence↗
PubMed1993

Monoclonal antibodies raised against membrane glycoproteins from mouse brain recognize N-linked oligomannosidic glycans.

Monoclonal L3 and L4 antibodies have been shown to recognize carbohydrate epitopes on several neural cell adhesion molecules; these epitopes can be released by treatment with endoglycosidase H. In the present study, we have identified the oligosaccharides released by endoglycosidase H from the cell adhesion molecules AMOG and L1 by fast-atom bombardment mass spectrometry as being solely of the oligomannosidic type. Using neoglycolipids of oligomannosidic glycans, we also report that both antibodies show the highest reactivity with the alpha-manno-pentaose Man alpha 1-3-[Man alpha 1-6(Man alpha 1-3)Man alpha 1-6]-Man, but decreasing reactivity with the alpha-manno-hexaose, heptaose, octaose and nonaose glycans. Thus, to our knowledge, we describe here for the first time monoclonal antibodies recognizing N-glycosidically linked oligomannosidic glycans.

Adenosine Triphosphatases↗
PubMed1993

[Irrigation-suction drainage and synovectomy in the treatment of empyema of the knee joint].

Following irrigation-suction drainage and synovectomy in 68 knee joints for empyema between 1971 and 1987, all were available for clinical and radiological follow-up. Since in 24 cases the empyema occurred after total knee arthroplasty, this group of patients was evaluated separately. The mean follow-up time in the no-prosthesis group was 8.3 and that in the prosthesis group, 5.3 years. In particular the aetiological factors, the bacterial pathogens and the effect of infection on radiological signs of degeneration were studied. The clinical results, including subjective findings, were assessed with the aid of HSS score. Our late results show that the prognosis for knee joint empyema can be rated as good if it is diagnosed early and treated aggressively. The poor outcome in a few cases was rather the result of underlying local disease and concomitant factors, and seemed not to be an immediate consequence of the infection itself. The relatively poor results in prosthesis group have to be referred predominantly to cases dating from the early years of total arthroplasty, with implants of the metal-on-metal type.

Adolescent↗
PubMed1993

Prosthetic valve function under simulated low cardiac output conditions: preliminary observations.

An experimental protocol was developed and a series of laboratory experiments started to assess the function and behaviour of replacement valves under simulated low cardiac output, that is low flow and low pressure conditions. The Helmholtz Institute's pulse duplicator (1) and instrumentation were carefully tuned in order to achieve accurate and reproducible delivery of the required extremely small stroke volumes. A pilot study was completed with 27 mm St. Jude Medical and CarboMedics bileaflet valves and Wessex porcine bioprostheses, three each, in the simulated aortic position. The results of these experiments suggest that the performances of the two bileaflet prostheses are inadequate if the flow is less than 2.0 l/min; the porcine bioprosthesis needs relatively low flow to start proper function, but its stenotic nature soon becomes apparent; increase in pressure without a corresponding increase in flow has a deleterious effect on valve performances by increasing regurgitation; increasing pulse rate is inversely correlated with valve efficiency; and there is no "all-or-none" cut off point between functional and non-functional situation for the tested devices; there is a semilogarithmic relation between increasing flow and valve performance. The clinical consequences are manifold and may be related both to the stabilization of circulation and to the increased thromboembolic risk during the early postoperative period.

Bioprosthesis↗