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Biomedical subjects

F Schmitz

Publications and source records attributed to F Schmitz.

At least 19 recordsLinked to original sources

Robust association of the APOE epsilon4 allele with premature myocardial infarction especially in patients without hypercholesterolaemia: the Aachen study.

BACKGROUND: Genetic influence on the manifestation of coronary artery disease (CAD) and myocardial infarction (MI) has been shown previously. From many candidate genes the APOE (apolipoprotein E) with the major alleles epsilon2/epsilon3/epsilon4 is in the focus of interest. MATERIALS AND METHODS: In 1817 patients admitted for their first left heart catheterization at a premature age (males < 55 and females < 65) the association of APOE alleles with MI was analysed. Genotyping was done by 5' exonuclease assay (TaqMan). RESULTS APOE was significantly associated with hypercholesterolaemia (epsilon4 72% vs. epsilon3 66% vs. epsilon2 51%; P < 0.0001), and premature MI (epsilon4 57% vs. epsilon3 50% vs. epsilon2 41%; P < 0.0001; hazard ratio 1.41, 95%CI 1.14-1.75). In patients without hypercholesterolaemia, the APOE allele epsilon4 was highly predictive for the presence of premature MI (epsilon4 55% vs. epsilon3 45% vs. epsilon2 28%; P < 0.0001; hazard ratio 1.75, 95%CI 1.19-2.57). CONCLUSION: The APOEepsilon4 allele shows a robust association with premature MI independent of hypercholesterolaemia.

Adult↗

Vascular endothelial growth factor (VEGF164) ameliorates intestinal epithelial injury in vitro in IEC-18 and Caco-2 monolayers via induction of TGF-beta release from epithelial cells.

OBJECTIVE: VEGF is a glycoprotein with various (e.g. angiogenic) activities. So far, research has focused on its angiogenic properties. VEGF receptors are localized on epithelial cells of patients with inflammatory bowel disease (IBD) and also on Caco-2 and IEC-18 cells. Our aim was to evaluate the role of VEGF on intestinal epithelial cell (IEC) migration and proliferation by utilizing an established in vitro model. METHODS: IEC-18 and Caco-2 monolayers were wounded with a razor blade as described previously. Cells were incubated in medium w/o rat VEGF(164). After 24 h, migration was assessed by counting cells across the wound edge. Migration was blocked with neutralizing TGF-beta(1) antibodies. IEC proliferation was assessed using the MTT (3-[4, 5-Dimethylthiazol-2-yl]-2, 5-diphenyl-tetrazolium bromide) test. Semi-quantitative changes of the TGF-beta(1) mRNA expression were evaluated before and after stimulation of the cells with VEGF(164) by RT-PCR. Statistical analysis was performed with ANOVA and the Wilcoxon test. RESULTS: VEGF(164) significantly induced epithelial cell migration in Caco-2 and IEC-18 cells compared to control. TGF-beta(1) antibodies completely abolished this VEGF-induced cell migration. TGF-beta(1) mRNA significantly increased in IEC-18 and Caco-2 cells after stimulation with VEGF. VEGF significantly inhibited epithelial cell proliferation in IEC-18 and in Caco-2 cells, indicating that the observed effects on cell migration were not due to any proliferate effects. CONCLUSION: VEGF effects on epithelial cell migration play an important part in epithelial cell restitution by maintaining mucosal homeostasis after mucosal injury. This effect is mediated by TGF-beta(1). Our results obtain another possible role for increased VEGF levels in the intestinal mucosa of patients with IBD as reported recently by others.

Animals↗

Mutations in the calcium-sensing receptor: a new genetic risk factor for chronic pancreatitis?

OBJECTIVE: In 2003 we identified a family with familial hypocalciuric hypercalcemia (FHH) (heterozygous CASR gene mutation L173P) and a mutation in the pancreatic secretory trypsin inhibitor gene (SPINK1) (N34S). While family members with an isolated calcium-sensing receptor gene (CASR) mutation remained healthy, a combination of the CASR and SPINK1 gene mutation caused chronic pancreatitis (CP). We thus speculate that the combination of two genetic defects affecting calcium homeostasis and pancreatic enzyme activation might represent a novel approach in chronic inherited pancreatic disease. We therefore sought to explore whether CASR gene mutations were prevalent in a cohort of patients with CP and confirmed SPINK1 mutations. MATERIAL AND METHODS: A cohort of 19 families (n=170) with a history of idiopathic CP (ICP) was screened for mutations within the CASR gene; 104 members of that cohort had a mutation (N34S) within the SPINK1 gene and 66 of those were suffering from CP. The entire CASR gene was screened for single strand conformation polymorphism under varying polyacrylamide gel conditions and subjected to direct dideoxy nucleotide sequencing of amplified cDNA. RESULTS: Single-strand conformation polymorphisms were observed in 59 samples, clustering of exons 3, 4 and 7. DNA sequence analysis revealed a yet unreported missense mutation in exon 7 (R896H) and two conservative mutations in exon 4 (F391F) and exon 7 (E790E). Furthermore, an intronic polymorphism in nucleotide position 493-19 G>A was detected in 19 out of 170 members of that cohort. CONCLUSIONS: We identified three novel calcium-sensing receptor gene mutations (1 missense mutation, 2 silent mutations and 1 intronic polymorphism) in a cohort of 19 families with ICP. In particular, the kindred with the R896H mutation presenting with a similar pedigree to the family described above may indicate a role for CASR gene mutations in SPINK1-related CP. Again, only the patient with the combination of both CASR and N34S SPINK1 gene mutation developed pancreatitis, whereas in the healthy parents and children only an isolated CASR or N34S SPINK1 gene mutation could be detected. We suggest that the CASR gene is a novel yet undetected co-factor in a multifactorial genetic setting of SPINK1-related pancreatitis that alters the susceptibility for pancreatitis in these patients.

Calcium Signaling↗

Identification of a novel calcium-sensing receptor gene mutation causing familial hypocalciuric hypercalcemia by single-strand conformation polymorphism analysis.

Calcium-sensing receptor gene (CASR) mutations that alter the function of the G protein coupled Ca (2+)-sensing receptor are reported in patients with familial hypocalciuric hypercalcemia (FHH), autosomal dominant hypocalcemia (ADH), and neonatal severe hyperparathyroidism (NSHPT). In search for novel disease causing mutations in the CASR gene, we screened exons 2 - 7 of the CASR gene of a family with FHH using single-strand conformation polymorphism analysis. We identified a novel CASR mutation (c.518 T > C; L173 P) in exon 4 encoding for the extracellular domain of the Ca (2+)-sensing receptor. This region seems to represent a hot spot within the CASR gene with at least 13 reported disease causing mutations thus far.

Adult↗

Glucagon-like peptide 2 improves intestinal wound healing through induction of epithelial cell migration in vitro-evidence for a TGF--beta-mediated effect.

BACKGROUND/AIMS: In vitro studies suggest that glucagon-like peptide 2 (GLP-2), secreted from enteroendocrine cells in the gastrointestinal tract after food intake, is able to ameliorate mucosal injury in settings of human disease characterized by injury and dysfunction of the intestinal mucosal epithelium. We evaluated this potential of GLP-2 after epithelial trauma by using two in vitro models measuring intestinal epithelial cell proliferation and cell migration. MATERIALS AND METHODS: Injuries were induced in confluent monolayers of the small intestinal cells lines IEC-6 and IEC-18, as well as in the colonic cell lines Caco-2 and Colo 320. GLP-2 (50-500 nM) or other peptides were added to the media. Wound healing was investigated after 24 h by quantification of the number of cells migrating across the wound edge. Proliferation of cells was assessed by using photometric mitochondrial incorporation measurement of MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide). Monoclonal TGF-beta antibodies were added to wounded monolayers to examine whether the GLP-2-induced wound healing was TGF-beta-mediated. RESULTS: Migration assessments revealed a significant stimulation of GLP-2-induced migration in IEC-6 and IEC-18 monolayers compared to the placebo group. No effect was observed in the colon cancer cell lines Caco-2 and Colo 320. Results of the proliferation assays show a significant inhibition of proliferation by GLP-2 in small intestinal cell lines whereas a dose-dependent stimulation of proliferation in colonic epithelial cells was observed. Addition of neutralizing TGF-beta1 antibodies to wounded IEC-6 and IEC-18 monolayers incubated with GLP-2 significantly reduced the number of migrating cells to the level of the placebo group. CONCLUSIONS: In our in vitro model, it was shown that the GLP-2-induced improvement of intestinal wound healing is TGF-beta-mediated. These effects were predominant in the epithelium of the small intestine compared to colonic epithelium. Our findings provide further insight into mechanisms leading to GLP-2-induced mucosal wound healing. These results suggest that GLP-2 or analogues of this peptide may potentially be useful for the treatment of intestinal disorders characterized by injury and ineffective repair of the intestinal mucosa.

Animals↗

[Inflammatory aortic aneurysm after vascular-prosthetic treatment. Morphological findings after years of incorporation].

Until now the causal and formal pathogenesis of the inflammatory aortic aneurysm is poorly known. This report shows the pathological- anatomical findings of surgical and autoptical preparations, on the one hand 78 months and on the other hand 82 months, after vascular-prosthetical treatment of inflammatory aneurysms in the abdominal and thoracal part of the aorta. By morphological studies it was possible to reveal, the over years existing disease, the typical picture of inflammatory aneurysm, focal destruction of the genuine aortic wall and partial substitution by inflammatory-fibrous, less qualitative granulation tissue. Even 6 1/2 years past the implantation of the Dacron-prosthesis, there is still no complete ingrown. In addition to the known findings of the transprosthetical organization with a variable development of the outer connective-tissued coat and neointima, the incorporated granulation-tissue was overlapped by a strong inflammation according to the basic disease. In several parts of the inflammatory destructed aortic wall, there is still no fixed incorporation of the prosthesis after 7 years, so that "hypermobile-prosthetic-parts" can be found as a result.

Aorta↗

[Morphological findings after stent implantation in the carotid artery].

This report describes the pathological-anatomical and immunohistochemical findings of carotid arteries after incorporation of self-expanding metal stents. Ten stent specimens were examined. All specimens displayed variable expression patterns of chronic low-grade foreign body reactions in the vicinity of the incorporated stent struts as characterized by the appearance of CD68-positive macrophages and mainly CD3- and CD45-R0-positive T lymphocytes. Overwhelming proliferations in relation to intimal hyperplasia can be regarded as the main cause of stent-associated vascular restenosis. After a period of 6 months the expression of factor VIII-positive neoendothelial cells on the luminal surface can be detected in individual cases. Reactions of the vascular wall depend on the state of the underlying atherosclerotic lesions prior to stenting. In cases of predominantly atheromatous soft plaques, the typical reaction pattern triggered by the metallic foreign body pressed into vessel tissue can be absent. In summary, the morphological findings show a chronic tissue reaction in response to stent incorporation. In addition, individually differing reaction patterns ranging from discrete inflammatory changes to massive stenoses were identified and documented.

Angioplasty, Balloon, Coronary↗

Acquired pure megakaryocytic aplasia: a separate haematological disease entity or a syndrome with multiple causes?

We report the case of a patient with acquired pure megakaryocytic aplasia. Until today, less than 20 cases of acquired pure megakaryocytic aplasia have been reported and the disease aetiology still seems to be unclear. This report summarizes the published data concerning possible aetiologies, treatment options and outcome of patients with acquired pure megakaryocytic aplasia. Furthermore, this case report presents an example for a possible disease progression.

Adult↗

The interleukin-6 promoter polymorphism is associated with elevated leukocyte, lymphocyte, and monocyte counts and reduced physical fitness in young healthy smokers.

Smoking and interleukin-6 are important factors in driving inflammation. This study assessed the relationship between smoking, interleukin-6 genotype, physical fitness, and peripheral blood count in healthy young men. For this interleukin-6 promoter polymorphism -174 genotype-phenotype association study 1,929 healthy German male aviators recruited at the central German Air Force Institute of Aviation Medicine were stratified by smoking habits. Cardiovascular fitness was expressed as maximal physical working capacity (PWCmax) in watts per kilogram body weight as assessed by maximal exercise testing by cycle ergometry up to physical exhaustion. Smokers had higher leukocyte and lymphocyte counts than nonsmokers and lower PWCmax. In the overall study population the C allele of the interleukin-6 polymorphism was weakly associated with elevated leukocytes and lymphocytes; in nonsmokers the interleukin-6 polymorphism was not associated with altered phenotypes, but in smokers the interleukin-6 C allele was associated with higher leukocytes, lymphocytes, and monocytes and with lower PWCmax. Smoking is thus associated with elevated leukocytes and lymphocytes and with reduced physical fitness. Gene carriers with the interleukin-6 C allele may suffer particularly from cigarette smoking.

Adult↗

Relation between the angiotensinogen (AGT) M235T gene polymorphism and blood pressure in a large, homogeneous study population.

The aim of this study was to assess the association of the angiotensinogen M235T polymorphism with arterial blood pressure (BP) at rest and under physical stress in a homogeneous large-scale study population. In all, 1903 men who passed routine medical examination for military flying duty were recruited. BP and heart rate were measured at rest, during, and after bicycle ergometry. Genotyping for the AGT M235T polymorphism was carried out by PCR and RFLP technique. The AGT T235 allele was associated with a significantly higher diastolic BP (n=1903; MM 81+/-8, MT 83+/-7, TT 83+/-8; P=0.003). Pulse pressure (PP) at rest differed significantly between AGT genotypes (n=1903; MM 51+/-10 mmHg, MT 49+/-10 mmHg, TT 49+/-10 mmHg; P=0.001). During physical activity, BP values showed no significant difference between genotypes. In healthy young men, the AGT T235 allele is significantly associated with elevated diastolic BP but also reduced PP at rest. During physical activity, the AGT polymorphism had no impact on blood pressure, indicating the existence of other counteracting mechanisms, which might balance the influence of this gene.

Adult↗

Cardiovascular risk factors in patients with aortic stenosis predict prevalence of coronary artery disease but not of aortic stenosis: an angiographic pair matched case-control study.

BACKGROUND: Traditional cardiovascular risk factors have been associated with aortic stenosis and coronary artery disease. As these two conditions often co-exist, the association of cardiovascular risk factors with aortic stenosis may reflect confounding. OBJECTIVE: To compare the cardiovascular risk profile in patients with severe aortic stenosis undergoing elective coronary angiography with that of patients without aortic stenosis or calcification undergoing coronary angiography for suspected coronary artery disease. METHODS: 523 patients referred for elective diagnostic left heart catheterisation because of severe aortic stenosis formed the case population; 3925 patients without valve disease referred for elective diagnostic left heart catheterisation formed the base control population. Of the latter, 523 were pair matched to the case population for sex, age, and prevalence of relevant coronary artery disease, forming a pair matched control population. Cardiovascular risk factors (male sex, hypertension, hypercholesterolaemia, smoking, diabetes mellitus, family history of coronary artery disease) were assessed in all the patients. RESULTS: None of the cardiovascular risk factors was more prevalent in patients with aortic stenosis than in the base control population or in the pair matched control population. However, male sex, hypercholesterolaemia, smoking, diabetes mellitus, and a family history of coronary artery disease were significantly associated with the presence of additional coronary artery disease in patients with aortic stenosis. CONCLUSIONS: Cardiovascular risk factors are commonly present in patients with aortic stenosis. However, when compared with controls matched for age, sex, and angiographically defined coronary artery disease, no risk factor was significantly associated with the prevalence of aortic stenosis. Thus other factors are likely to be more important in the pathogenesis of aortic stenosis.

Aged↗

The neural basis of intermittent motor control in humans.

The basic question of whether the human brain controls continuous movements intermittently is still under debate. Here we show that 6- to 9-Hz pulsatile velocity changes of slow finger movements are directly correlated to oscillatory activity in the motor cortex, which is sustained by cerebellar drive through thalamus and premotor cortex. Our findings suggest that coupling of 6- to 9-Hz oscillatory activity in the cerebello-thalamo-cortical loop represents the neural mechanism for the intermittent control of continuous movements.

Adult↗

The effects of acetylsalicylic acid on proliferation, apoptosis, and invasion of cyclooxygenase-2 negative colon cancer cells.

BACKGROUND: Acetylsalicylic acid (ASA, aspirin), the most common nonsteroidal anti-inflammatory drug (NSAID), has been shown to have a protective effect against the incidence and mortality of colorectal cancer. However, the mechanism of its anticancer function remains unclear. The aim of this study was to determine the effects of acetylsalicylic acid on proliferation, apoptosis, and invasion in human cyclooxygenase-2 (COX-2) negative colorectal cancer cell lines. MATERIALS AND METHODS: After treatment with various concentrations of ASA, cell proliferation was measured in the human colon cancer cell line SW480. Apoptotic cells were identified by transmission electron microscopy, acridine orange staining, and flow cytometry. The invasive potential of SW480 cells was detected using an in vitro invasion assay. The production of carcinoembryonic antigen was measured by microparticle enzyme immunoassay. Expression of Bcl2, Bax, CD44v6, and nm23 were evaluated by immunocytochemistry. RESULTS: ASA significantly inhibited the proliferation of SW480 cells and stimulated apoptosis. Production of carcinoembryonic antigen and the invasive potential of SW480 cells were also inhibited by ASA. After treatment with ASA, down-regulation of Bcl2 and CD44v6 expression and up-regulation of nm23 expression were observed in SW480 cells. No obvious effect of ASA was found on Bax expression. CONCLUSION: Our findings reveal that ASA inhibits the proliferation and promotes apoptosis in the human colon cancer cell line SW480. Down-regulation of Bcl2 expression might represent a potential mechanism by which ASA induces apoptosis in this COX-2 negative colon cancer cell line. Our results also suggest that ASA decreases the invasive potential of these colon cancer cells. Decreased CEA content and CD44v6 expression and elevated nm23 expression may contribute to the effect of ASA on invasive potential of SW480 colon cancer cells.

Anti-Inflammatory Agents, Non-Steroidal↗

[The nuclear medicine department and the TEP/Biomedical Cyclotron unit].

During the last 25 years, the clinical and experimental activity in nuclear medicine at Erasme hospital has been influenced by the implementation of positron emission tomography (PET) in 1990 as a method of brain functional investigation. The activity of the PET/biomedical cyclotron unit has been dedicated to various subjects in neurology, neurosciences, psychiatry, oncology and cardiology. This has been made possible by developments in radiochemistry. The radiochemistry laboratory has designed and produced original tracers such as 9-[(3-[18F]fluoro-1-hydroxy-2-propoxy)-methyl]guanine (FHPG), a tracer of viral thymidine kinase activity in gene therapy protocols. We have brought new applications of PET, such as its integration into stereotactic neurosurgical and radioneurosurgical techniques in order to improve their diagnostic and therapeutic performance in neurooncology. We have also conducted multiple studies on brain physiology and pathophysiology, in particular with the use of functional and metabolic brain mapping methods and the use of tracers of neurotransmission systems. The Department of nuclear medicine has also performed studies on bone metabolism and investigated in vivo imaging methods of infectious and immune processes.

Belgium↗

Cellular expression of CCK-A and CCK-B/gastrin receptors in human gastric mucosa.

Gastrin stimulates gastric acid secretion in various species, but the role of the structurally related CCK for the peripheral regulation of acid secretion in humans remains controversial. Moreover, species differences in CCK receptor function and expression have been reported. We therefore sought to identify the cellular targets of CCK and gastrin within the human gastric mucosa in situ. Gastric biopsies were collected from 15 patients without gastric disease. Expression of CCK receptor subtypes was detected in individual cells of the gastric mucosa by reverse transcription (RT)-PCR in situ, immunohistochemistry and confocal laser scanning microscopy, using antisera against the CCK-A or CCK-B/gastrin receptor subtype. Both CCK-A and CCK-B receptors were detected in antral and oxyntic mucosa at the mRNA and protein level. In fundic mucosa, CCK-A receptor mRNA and protein mapped to D cells (37.4+/-7.7). Besides, individual chief cells, mucous neck cells and parietal cells (12.3+/-4.7%) expressed CCK-A receptors. CCK-B/gastrin receptor mRNA and protein were detected in parietal cells (57.4+/-11.1%) and in neuroendocrine cells (33.2+/-4.4%) expressing chromogranin A. Furthermore, epithelial cells within the neck of the gastric gland were found to express the CCK-B/gastrin receptor. We conclude that (i) identification of CCK-A receptors on somatostatin producing D cells in humans provide the anatomical basis for a receptor-mediated mode of action of CCK on somatostatin release and (ii) detection of either CCK receptor subtype in the putative stem cell compartment implies a role of CCK in the maintenance of tissue homeostasis in human gastric mucosa.

Adult↗

Immunological heterogeneity of synaptic and extrasynaptic forms of non-erythroid alpha-spectrin in the rat retina.

alpha-, beta- Spectrin is ubiquitously distributed in neuronal compartments, i.e. at the plasma membrane of neuronal cell bodies, axonal and dendritic processes, pre- and postsynaptic nerve terminals and around synaptic vesicles, "Brain Res. Bull. 50 (1999) 345". Ultrastructural analyses in the rat retina using the monoclonal antibody AA6, "Hear. Res. 43 (1990) 199", against non-erythroid alpha-spectrin, alphaSPII (spectrin nomenclature according to "Blood 81 (1993) 3173"), revealed that the antibody intensively labeled the cytoplasmic face of the plasma membrane in virtually all neuronal processes. However, no significant immunolabel was observed at the presynaptic plasma membrane, around synaptic vesicles, at presynaptic densities and synaptic ribbons. Therefore, synaptic non-erythroid alpha-spectrin differs immunologically from extrasynaptic non-erythroid alpha-spectrin. This heterogeneity might contribute to the generation of distinct retinal microdomains.

Animals↗

Identification of CCK-B/gastrin receptor splice variants in human peripheral blood mononuclear cells.

There is increasing evidence for a direct interaction of the enteric nervous and immune system. Receptors for neuropeptides such as VIP, somatostatin, and substance P have been characterised in human immuno-haematopoietic cells but little is known about the functional significance and expression of receptors for cholecystokinin (CCK) on cells of the immune system. There are only few studies that describe the expression of CCK receptors on human leukaemia-derived cell lines but the receptor structure and function in normal leukocytes have not been clearly established. We therefore sought to determine CCK receptor expression, structure, and function in nontransformed human peripheral blood mononuclear cells.Full-length cDNA clones encoding the human CCK-A and CCK-B/gastrin receptor are expressed in peripheral blood mononuclear cells from healthy volunteers without haematopoietic malignancy. In addition to wild-type CCK-B/gastrin receptor cDNAs, we isolated a splice variant with an in frame insertion of 69 amino acids within its putative third intracellular receptor loop. Dideoxy sequence analysis revealed that the cDNA of this splice variant comprises exons 1-4 but retains intron 4 (207 bp) in the absence of mutations within the splice donor sites. Transient expression of this splice variant in COS-7 cells reveals wild-type affinity for CCK-8, Gastrin-17, and antagonist L-365,260. Affinity for glycine-extended gastrin-17 was not increased when compared to the wild-type CCK-B/gastrin receptor. In vitro, gastrin decreased 3H-thymidine labelling in phytohaemagglutinin-pretreated mononuclear cells at a half-maximally effective concentration of 1.5 nM. We also isolated a cDNA encoding another splice variant of the CCK-B/gastrin receptor with a 158 bp deletion of the entire exon 4 sequence. We conclude that wild-type transcripts of both CCK receptor subtypes and splice variants of the CCK-B/gastrin receptor are expressed in nontransformed human mononuclear cells and that gastrin exhibits antiproliferative effects.

Alternative Splicing↗

The synaptic vesicle priming protein Munc13-1 is absent from tonically active ribbon synapses of the rat retina.

Ribbon synapses, for example of the retina, are specialized synapses that differ from conventional, phasically active synapses in several aspects. Ribbon synapses can tonically and yet very rapidly release neurotransmitter via synaptic vesicle exocytosis. This requires an optimization of the synaptic machinery and is at least partly due to the presence of synaptic ribbons that bind large numbers of synaptic vesicles and which are believed to participate in priming synaptic vesicles for exocytosis. In this paper we analyzed whether ribbon synapses of the retina employ similar priming factors, i.e. Munc13-1, as do conventional, non-ribbon containing phasically active synapses. We found that though present in conventional synapses of the retina Munc13-1 was completely absent from ribbon-containing synapses of the retina, both in the outer as well as in the inner plexiform layer. This indicates that ribbon synapses of the retina employ other, possibly more potent priming factors than phasically active conventional synapses.

Animals↗