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Biomedical subjects

M Herrmann

Publications and source records attributed to M Herrmann.

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

Flow cytometric discrimination between viable neutrophils, apoptotic neutrophils and eosinophils by double labelling of permeabilized blood granulocytes.

Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) is frequently used to detect apoptotic cells in tissues, cytospins and suspensions. Here we show that TUNEL staining of freshly isolated granulocytes results in non-specific positivity of a distinct population, which can be observed in the presence or absence of TdT. The morphological features of the false-positive cells examined in fluorescence microscopy suggest that the non-specifically stained cells are eosinophilic granulocytes. Granules of eosinophilic granulocytes were brightly stained by non-specific TUNEL reaction independent of TdT. This staining does not, therefore, indicate apoptosis and most likely reflects 'stickiness' of the permeabilized eosinophils. Immunofluorescence with phycoerythrin (PE)-labelled CD16 antibodies performed simultaneously with conventional TUNEL staining confirmed that the false-positive cells in TUNEL staining were CD16-negative eosinophils. In this report we describe a new procedure that allows: (i) the differentiation of neutrophilic and eosinophilic granulocytes in forward scatter versus log side scatter histograms after permeabilisation; (ii) the reliable discrimination between viable neutrophils, apoptotic neutrophils and eosinophilic granulocytes in cytofluorimetry.

Apoptosis↗
PubMed2000

Aminopeptidase N/CD13 is directly linked to signal transduction pathways in monocytes.

In the present study, we characterized in monocytes the rise in [Ca(2+)](i) evoked by monoclonal antibodies (mAbs) to aminopeptidase N (APN)/CD13, showing a two-phase calcium increase with a small-belled [Ca(2+)](i) rise due to the release of calcium from intracellular stores and a more sustained plateau due to the influx of calcium from the extracellular environment. Tyrosine kinase inhibitors were able to inhibit the rise in [Ca(2+)](i) induced by ligation APN/CD13, as were inhibitors of the phosphatidylinositol 3-kinase. For the first time we can show that mAbs to APN/CD13 provoke phosphorylation of the mitogen-activated protein kinases ERK1/2, JNK, and p38. Furthermore, we show that mRNA of the chemotactic cytokine IL-8 is upregulated under the influence of APN/CD13 ligation. Although the in vivo ligand as well as possible cooperating membrane molecules remains to be identified, our results suggest that the membrane ectoenzyme APN/CD13 is a novel signal transduction molecule in monocytes.

Androstadienes↗
PubMed2000

Effect of atenolol and celiprolol on acetylcholine-induced coronary vasomotion in coronary artery disease.

Earlier studies have reported on the potentiated muscarinic vasoconstriction of intracoronary acetylcholine after metoprolol application in patients with coronary artery disease. The present study investigated the effect of celiprolol, atenolol, and placebo on acetylcholine-induced vasomotion in patients with coronary artery disease. Furthermore, direct effects on coronary vasomotion and on hemodynamics were evaluated. Acetylcholine (intracoronary concentrations of 6.3x10(-7), 2.0x10(-6), and 6.3x10(-6) M) was given before and after double-blind celiprolol (0.30 mg/kg IV), atenolol (0.15 mg/kg IV), or placebo in 3x12 patients. Vasomotion was investigated by quantitative coronary angiography in proximal and distal segments of epicardial coronary arteries, and by the determination of the coronary resistance index based on Doppler-flow measurements. The investigated drugs had no direct affect on the diameter of the epicardial coronary arteries. However, celiprolol, in contrast to atenolol, significantly reduced systemic vascular resistance (change after atenolol: from 1,855+/-308 to 2,161+/-550 dyne s cm(-5); celiprolol: 1,691+/-435 to 1,411+/-343 dyne s cm(-5); and placebo: 1,722+/-215 to 1,710+/-213 dyne s cm(-5), p<0.001) and the coronary resistance index (change after atenolol: 2.52+/-3.58 to 2.86+/-4.24; celiprolol: 2.70+/-1.55 to 2.49+/-2.26; and placebo: 1.97+/-1.35 to 1.92+/-1.25, p<0.01). Celiprolol, atenolol, and placebo did not have different effects on acetylcholine-induced coronary vasomotion of epicardial conductance vessels (diminution of proximal lumen diameter before/after atenolol: 0.42+/-0.39/0.44+/-0.39 mm; celiprolol: 0.32+/-0.26/0.30+/-0.24 mm; and placebo: 0.36+/-0.29/0.43+/-0.40 mm) and of coronary resistance vessels (reduction of coronary resistance index before/after atenolol: 1.95 +/-4.74/ 1.92+/-3.74; celiprolol: 0.98+/-0.73/1.41+/-1.50; and placebo: 1.16+/-1.29/1.16+/-1.04). In contrast to atenolol, celiprolol possesses vasodilative properties in systemic and coronary resistance vessels. There was no direct effect on the diameter of conductance vessels. Acetylcholine-induced coronary vasomotion both in conductance and resistance vessels was not influenced by the beta blockers that were studied. This suggests that atenolol and celiprolol do not influence endothelium-dependent, nitric oxide related vasomotion.

Acetylcholine↗
PubMed2000

Fine-needle aspiration of the thyroid: rate and causes of cytohistopathologic discordance.

Fine-needle aspiration (FNA) of the thyroid gland is a widely utilized, sensitive, specific, and cost-effective method for the evaluation of thyroid nodules. The purpose of this study was to evaluate the accuracy of thyroid FNA and causes of cytohistological discordance in our institution. Six hundred twenty-five thyroid FNAs obtained from 503 females (mean age, 54) and 122 males (mean age, 51) in whom histopathologic follow-up material was available for review, were analyzed. FNAs were classified as: nondiagnostic, negative, intermediate, and positive for malignancy, and the histopathologic material was categorized as benign or malignant. The review revealed 93% sensitivity and 96% specificity for the FNA diagnoses. The FNA results were diagnostic in 87%, indeterminate in 6%, and nondiagnostic in 7% of the cases. Cytohistologic correlation was achieved in 88% of the cases. The false-negative rate was 4% and the false-positive rate was 8%. The most common pitfalls for false-negative diagnoses consisted of suboptimal material and underdiagnosis of papillary carcinoma due to cystic degeneration. The most common pitfall for false-positive cases was overdiagnosis of follicular neoplasms. Our study confirmed that FNA of thyroid nodules can be performed with high sensitivity and specificity by experienced clinicians or pathologists. The application of strict specimen adequacy rules for FNA interpretation is likely to decrease the rate of false-negative and false-positive diagnoses.

Adult↗
PubMed2000

[Use of the heart-lung machine in extra-cardial carcinoma surgery].

The employment of the heart-lung machine to assisting the circulatory system for the resection of extracardial tumors is increasing because of their location, growth and infiltration. We report on three patients in whom the resection of the tumor was only possible with extracorporeal circulation (ECC). In the first patient sarcoma of the pulmonary artery and valve was resected under ECC. Artery and valve were replaced with a cryo-preserved valved bifurcation homograft. In the other patients ECC was used on the basis of tumorinfiltration of the inferior vena cava and tumor embolus of the pulmonary artery in a case of primary renal cell carcinoma, and tumor infiltration of the superior vena cava and right atrium in a case of follicular thyroid carcinoma. All patients had a good postoperative course and excellent long term survival.

Adenocarcinoma, Follicular↗
PubMed2000

Impairment of genomic DNA binding to a putative dysfunctional receptor on erythrocytes independent of complement and antibodies in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is characterized by a variety of autoantibodies and other immune abnormalities indicative of an immunological hyperactivity. Antibodies against native DNA, however, are a disease-specific marker and play a major role in the pathogenesis of systemic or organ-specific disease manifestations. Nevertheless, the mechanisms causing the appearance of autoantibodies and immune complexes in SLE are not yet understood. Here, we report that chromosomal DNA and other forms of nucleic acids are usually cleared from circulation by binding to a yet unidentified receptor-like protein on the surface membrane of erythrocytes, independently from complement or antibodies. The binding kinetics of DNA and other nucleic acids to erythrocytes are significantly altered in SLE patients, showing an overall reduced binding capability and presaturated binding kinetics. Significant amounts of chromosomal DNA can be isolated from erythrocytes of SLE patients but not from normal controls. Electron microscopy shows electron-dense particles on the surface of SLE erythrocytes (approximate size 20-40 nm). Comparative genomic hybridization reveals that the nucleic acid isolated from erythrocytes of SLE patients is of genomic and random origin, leading to an accumulation of "free" nucleic acids in the periphery, which eventually induces a B-cell immune response.

Antibodies↗
PubMed2000

Identification of plasma proteins adsorbed on hemodialysis tubing that promote Staphylococcus aureus adhesion.

Risk factors for Staphylococcus aureus infections in patients undergoing hemodialysis include underlying disease, material-induced host defects, and the presence of vascular access catheters. To determine the specific contribution of various potentially adsorbed plasma components in promoting S aureus adhesion to shunt tubing during chronic hemodialysis, we quantified their respective amounts by Western immunoblotting and densitometry and estimated their individual adhesion-promoting activities with specific adhesion-modified bacterial mutants. Fibrinogen, which was the only component consistently present in tubing protein extracts from all patients, was adsorbed in significantly higher amounts on predialyzer than on postdialyzer tubing segments. In contrast, fibronectin and von Willebrand factor were irregularly present in patients' tubing, whereas vitronectin or thrombospondin remained undetectable in all samples. The contribution of fibrinogen in promoting S aureus attachment to hemodialysis tubing was demonstrated by (1) the significantly lower adhesion of a cIfA mutant of strain Newman compared with its parent; (2) the increased attachment of strain 8325-4 after complementation with the cloned cIfA gene on the multicopy plasmid pCF4; and (3) the general tendency for strains Newman and 8325-4(pCF4) to express higher attachment on predialyzer compared with postdialyzer tubing segments in relationship with the higher content of fibrinogen on the former material. However, the specific S aureus attachment-promoting activity of both prefilter and postfilter tubing-adsorbed fibrinogen were much lower than that of the native in vitro-adsorbed protein and may reflect masking or inactivation of the in vivo-adsorbed protein by unknown mechanisms.

Adsorption↗
PubMed2000

Low-dose radiotherapy selectively reduces adhesion of peripheral blood mononuclear cells to endothelium in vitro.

BACKGROUND AND PURPOSE: The anti-inflammatory effect of low-dose radiotherapy (LD-RT) still is not understood. The adhesion of leukocytes to endothelial cells (EC) of the vessel wall is the initial event of tissue invasion, and thus, crucially contributes to the regulation of inflammation. We investigated the influence of LD-RT on the adhesion process in vitro. MATERIALS AND METHODS: Isolated peripheral-blood-mononuclear-cells (PBMC) were incubated with an activated murine endothelioma cell-line under shear conditions at 4 degrees C after irradiation with single doses between 0.1 and 10.0 Gy. Adherent cells were counted microscopically and compared to a non-irradiated control. In parallel, viability and expression of adhesion molecules, especially of L-selectin, and lineage-specific markers on the cell surface were determined by dye exclusion and cytofluorometry, respectively. Modulation of adhesion by soluble L-selectin was tested in the adhesion assay. RESULTS: Radiation doses of 0.1-0.5 Gy reduced the adhesion of viable PBMC to EC in vitro by 70% of the control level 4 h after irradiation. Leukocytes showed a marked reduction of L-selectin expression after LD-RT. Soluble L-selectin can inhibit the adhesion of PBMC to EC. CONCLUSION: The anti-inflammatory effect of LD-RT might, in part, be due to the reduction in the adhesion of PBMC to EC. This reduction in adhesion might be a consequence of the reduced expression of L-selectin on the surface of PBMC, and the inhibition of adherence by soluble L-selectin shed by PBMC in vitro.

Adult↗
PubMed2000

Frontal-executive dysfunction in early onset cerebellar ataxia of Holmes' type.

We report the case of a 29-year-old male patient with cerebellar ataxia of Holmes' type. The combination of progressive cerebellar ataxia and hypogonadotrophic hypogonadism is a rare distinctive syndrome which was first described by Holmes in 1907. Early diagnosis is desirable because replacement of testosterone may allow normal sexual development. MRI showed severe combined superior vermian and cerebellar hemisphere atrophy. Comprehensive neuropsychological testing pointed to a more widespread cerebellar mediated functional CNS involvement in the earlier stages of this ataxic syndrome than previously described in mentally not retarded subjects.

Adult↗
PubMed2000

Stress and rheumatic diseases.

This study was done to review the literature concerning the influence of minor and major stress factors on onset and course of rheumatoid arthritis (RA), juvenile chronic arthritis (JCA), systemic lupus erythematosus (SLE), and fibromyalgia syndrome (FS). Major life events and chronic minor stress seem to be very important factors in JCA and are significantly associated with the onset of the disease. With respect to RA and FS, stress may be a provoking factor but the data in the literature are equivocal. However, during the course of the disease, minor stress aggravates SLE, FS, JCA, and RA. Patients with FS and RA may profit from psychological therapies. Optimistic and confronting coping strategies were found most frequently and perceived to be most effective. Very important for psychological function is the social background, especially the functioning of the family is of outstanding importance for clinical and psychological outcome.

Adaptation, Psychological↗
PubMed2000

Role of apoptosis in autoimmunity.

Apoptosis is a physiological form of cell death required to ensure that the rate of cell division is balanced by the rate of cell death in multicellular organisms. Dysregulation of apoptosis is associated with the pathogenesis of a wide array of diseases: cancer, neurodegeneration, autoimmunity, heart disease and others. In this review we collect arguments supporting a hypothesis of a dysregulated apoptosis leading to development of autoimmunity like systemic lupus erythematosus (SLE). This notion is supported by occurence of known autoantigens in apoptotic blebs, in vitro findings of an increased rate of apoptotic lymphoblasts despite optimal cytokine stimulation combined with a defective in vitro clearance of apoptotic bodies by SLE phagocytes. Moreover, we and others could generate histone-specific lymphocytic cell lines from cells after activation with autologous apoptotic material. These lymphocytes could stimulate autologous B-lymphocytes to produce of anti-dsDNA antibodies, a diagnostic hallmark for SLE. Finally, antibodies against phospholipids like phosphatidylserine are often associated with systemic autoimmunopathies like SLE and others. Phosphatidylserine is exposed on apoptotic cells as early sign of programmed cell death and serves as phagocyte recognition molecule for apoptotic cells. Formation of immune complexes and deposition in tissues might lead to organ damage and disease. This scenario will be discussed in this review in detail.

Animals↗
PubMed2000

Clinical presentation and mutation identification in the NBS1 gene in a boy with Nijmegen breakage syndrome.

Nijmegen breakage syndrome (NBS) is a rare autosomal recessive disorder which belongs to the group of inherited chromosomal instability syndromes. The clinical characteristics include severe microcephaly, a dysmorphic facies, and immunodeficiency with predisposition to malignancies. While the cellular characteristics of ataxia teleangiectasia (AT) and NBS are similar, the clinical findings are quite distinct. NBS patients show characteristic microcephaly, which is rare in association with AT and they do not develop ataxia and teleangiectasia. Recently, the gene mutated in NBS has been identified. Here we report a 5-year-old Bosnian boy with severe microcephaly. Because of multiple structural aberrations involving chromosomes 7 and 14 typical for AT (MIM 208900) and NBS (MIM 251260), AT was diagnosed. We suggested the diagnosis of NBS because of the boy's remarkable microcephaly, his facial appearance, and the absence of ataxia and teleangiectasia. DNA analysis was performed and revealed that the boy is homozygous for the major mutation (657de15) in the NBS1 gene. This finding confirms the diagnosis of NBS in our patient and offers the possibility to perform a most reliable prenatal diagnosis in a further pregnancy.

Adult↗
PubMed2000

Treatment with annexin V increases immunogenicity of apoptotic human T-cells in Balb/c mice.

Exposure of phosphatidylserine on the outer leaflet of the cytoplasmic membrane is an early event during apoptotic cell death and serves as a recognition signal for phagocytes. Usually the clearance of apoptotic cells does not initiate inflammation or immune response. We investigated the immune response in Balb/c mice towards apoptotic human T-cells. Animals injected with apoptotic cells showed significantly reduced humoral immune responses, especially Th1-dependent IgG2a titres, compared to controls immunised with viable cells. However, treatment of apoptotic cells with annexin V (AxV) significantly increased the humoral immune response. AxV binds with high affinity to anionic phospholipids and as a result interferes with the phosphatidylserine recognition by phagocytes. Our results indicate that AxV treatment may be used to increase the efficiency of apoptotic cell-based vaccines, e.g. some tumour vaccines.

Animals↗
PubMed2000

Mercury induces cell cytotoxicity and oxidative stress and increases beta-amyloid secretion and tau phosphorylation in SHSY5Y neuroblastoma cells.

Concentrations of heavy metals, including mercury, have been shown to be altered in the brain and body fluids of Alzheimer's disease (AD) patients. To explore potential pathophysiological mechanisms we used an in vitro model system (SHSY5Y neuroblastoma cells) and investigated the effects of inorganic mercury (HgCl2) on oxidative stress, cell cytotoxicity, beta-amyloid production, and tau phosphorylation. We demonstrated that exposure of cells to 50 microg/L (180 nM) HgCl2 for 30 min induces a 30% reduction in cellular glutathione (GSH) levels (n = 13, p<0.001). Preincubation of cells for 30 min with 1 microM melatonin or premixing melatonin and HgCl2 appeared to protect cells from the mercury-induced GSH loss. Similarly, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assays revealed that 50 microg/L HgCl2 for 24 h produced a 50% inhibition of MTT reduction (n = 9, p<0.001). Again, melatonin preincubation protected cells from the deleterious effects of mercury, resulting in MTT reduction equaling control levels. The release of beta-amyloid peptide (Abeta) 1-40 and 1-42 into cell culture supernatants after exposure to HgCl2 was shown to be different: Abeta 1-40 showed maximal (15.3 ng/ml) release after 4 h, whereas Abeta 1-42 showed maximal (9.3 ng/ml) release after 6 h of exposure to mercury compared with untreated controls (n = 9, p<0.001). Preincubation of cells with melatonin resulted in an attenuation of Abeta 1-40 and Abeta 1-42 release. Tau phosphorylation was significantly increased in the presence of mercury (n = 9, p<0.001), whereas melatonin preincubation reduced the phosphorylation to control values. These results indicate that mercury may play a role in pathophysiological mechanisms of AD.

Amyloid beta-Peptides↗
PubMed2000

Dominant T cells in idiopathic nephrotic syndrome of childhood.

BACKGROUND: Because of several studies, idiopathic nephrotic syndrome (INS) of childhood is suspected to have an immunologic pathogenesis with T cells playing a major role. To investigate this hypothesis further, we studied the diversity of the CDR3 region of the T-cell receptor (TCR) beta-chain from peripheral T cells isolated from patients with INS. METHODS: The study was performed over a three-year period to obtain longitudinal data on the repertoire of peripheral T cells. mRNA from peripheral mononuclear cells (PBMCs) of seven INS patients and two healthy controls (NHD) was prepared and analyzed for CDR3 length polymorphism of TCR beta-chain by spectratyping. RESULTS: All INS patients presented individually skewed spectratype histograms in at least one Vbeta-family. Patients suffering from a frequent relapsing course of INS or a focal global sclerosis showed some alterations to persist in all samples isolated in the observation period (up to 3 years). In addition, sequence analyses of the beta-chain of the TCR CDR3 region confirmed clonal expansion of peripheral T cells in those patients who had displayed spectratype alterations. CONCLUSIONS: The data give strong evidence for an direct involvement of CD8+ T cells in the complicated course of INS.

Age of Onset↗