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Biomedical subjects

M Brehm

Publications and source records attributed to M Brehm.

17 recordsLinked to original sources
PubMed2006

Increased cardiac mRNA expression of matrix metalloproteinase-1 (MMP-1) and its inhibitor (TIMP-1) in DCM patients.

Left ventricular dilation and myocardial remodeling are hallmarks of dilated cardiomyopathy (DCM). It is assumed that left ventricular dilation is caused by the disintegration of the collagenous network by increased collagenolytic activity of matrix metalloproteinases (MMPs) and their adequate tissue inhibitors (TIMPs). In this study the myocardial MMP-1 and TIMP-1 mRNA expressions were investigated by using real-time quantitative PCR analysis from right septal endomyocardial biopsies of patients with dilated cardiomyopathy (n = 46) and control subjects (n = 11). The volume density (Vv%) of collagen was measured morphometrically. Classification was done according to LV diameters [left ventricular enddiastolic diameter (LVEDD, cm) calculated to body surface area (BSA, m(2))] into three DCM groups: group I (LVEDD-BSA > 2.7-3.0 cm/m(2)), group II ( > 3.0-3.6 cm/m(2)), group III ( > 3.6 cm/m(2)), controls (< 2.7 cm/m(2)). Compared with controls, the MMP-1 expression in patients with DCM was significantly increased (119.2 +/- 45.2 vs. 1.3 +/- 0.4; p < 0.001) as was TIMP-1 expression (9.6 +/- 1.2 vs. 1.3 +/- 0.4; p < 0.01). Moreover the MMP-1 and TIMP-1 expression varied according to LV diameter: group I (MMP-1: 8.7 +/- 3.5; p = 0.33; TIMP- 1: 4.5 +/- 1.2; p < 0.01); group II (MMP-1: 211.4 +/- 86.0; p < 0.001; TIMP-1: 12.5 +/- 1.9 ; p < 0.001); group III (MMP-1: 38.8 +/- 22.6; p < 0.01; TIMP-1: 8.1 +/- 1.7; p < 0.001). Compared with controls, the collagen level in DCMPt. was significantly increased: 5.0 +/- 0.6 vol% vs 1.2 +/- 0.2 vol% p < 0.001 and correlates with LV diameter. This study reveals that the overexpression of MMP-1, which is associated with an increased ratio of MMP-1/TIMP-1 in DCM, indicates an activated collagenolytic system while replacement fibrosis is accumulating. The MMP-1 overexpression is mainly found in moderately dilated DCM hearts (group II) indicating the dynamic process of LV dilation and the importance of collagenases in the early phase of LV remodeling.

Biomarkers↗
PubMed2006

[Intra-arterial and intramuscular transplantation of adult, autologous bone marrow stem cells. Novel treatment for therapy-refractory peripheral arterial occlusive disease].

HISTORY AND CLINICAL FINDINGS: A 62-year-old man had limb ischemia in stage IIb (Fontaine's classification). After surgical and interventional measures the right superficial femoral artery had remained occluded for more than one year. The patient's walking distance was only 100 meters. It was therefore decided to do a combined intraarterial and intramuscular transplantation of stem cells into the right limb. INVESTIGATIONS: Before and 10 weeks after the transplantation noninvasive tests, namely walking distance, ankle-brachial index at rest and during exercise, occlusion plethysmography and capillary venous oxygen saturation were measured. The patient was also asked to fill in a questionnaire of his symptoms. THERAPY AND RESULTS: After harvesting the patient's bone marrow the mononuclear cell fraction was separated (109.8 x 10(6)). Afterwards 10 ml of the cell suspension were injected into the right superficial femoral artery and 5 ml each of the suspension was injected into 5 different locations of the quadriceps femoris and the gastrocnemius muscles. After 10 weeks" follow-up a seven-fold improvement of walking distance and an increase of tissue oxygen saturation of more then 50% were recorded. The ankle-brachial index at rest remained unchanged, but on exercise it increased by 24%. CONCLUSION: The combined intraarterial and intramuscular transplantation of human autologous bone marrow stem cells may be a novel and clinically feasible treatment for patients with severe chronic limb ischemia. The success of this approach may be the result of increased neo-angiogenesis, especially of the small muscle-supplying vessels.

Arterial Occlusive Diseases↗
PubMed2005

Comparing grazing on lake seston by Dreissena and Daphnia: lessons for biomanipulation.

Biomanipulation measures in lakes, taken to diminish algal blooms, have mainly been restricted to the reduction of zooplanktivorous fish with the aim to stimulate the grazing pressure by native filter feeders such as Daphnia. However, larger filter feeders like the exotic zebra mussel, Dreissena polymorpha, have been suggested as an optional tool because of their high filtering capacity. We compared grazing by two filter feeders, D. polymorpha and Daphnia galeata, offered seston from Lake IJsselmeer, the Netherlands in two consecutive years: 2002 and 2003. The seston in both years was dominated by the colony-forming cyanobacterium Microcystis aeruginosa. The grazing studies were performed under controlled conditions in the laboratory and samples were analyzed on a flow cytometer, making it possible to quantify grazing on different seston components and size fractions, including cyanobacteria, other phytoplankton (green algae, diatoms, etc.), and detritus. No differences in clearance rates, on a per weight basis, were found between the two grazer species. The clearance rate on cyanobacteria (especially <20 microm) was lower in 2003 than in 2002. In 2003, the microcystin concentration of cyanobacteria was higher than in 2002, suggesting that the observed lower clearance rate in 2003 was due to the enhanced toxin content of the cyanobacteria. Zebra mussels, although indiscriminately filtering all seston groups out of the water, positively selected for phytoplankton in their mantle cavity, irrespective of its toxicity, and rejected detritus. Since no differences in clearance rates were found between the two grazer species, we conclude that for biomanipulation purposes of shallow lakes, native species like the daphnids should be preferred over exotic species like zebra mussels. When the seston is dominated by phytoplankton that cannot be filtered out of the water column by Daphnia, however, the use of zebra mussels may be considered. Care should be taken, however, in the choice of the lakes since the mussels may have severe ecological and economic impacts.

Animals↗
PubMed2005

Full-genome RNAi profiling of early embryogenesis in Caenorhabditis elegans.

A key challenge of functional genomics today is to generate well-annotated data sets that can be interpreted across different platforms and technologies. Large-scale functional genomics data often fail to connect to standard experimental approaches of gene characterization in individual laboratories. Furthermore, a lack of universal annotation standards for phenotypic data sets makes it difficult to compare different screening approaches. Here we address this problem in a screen designed to identify all genes required for the first two rounds of cell division in the Caenorhabditis elegans embryo. We used RNA-mediated interference to target 98% of all genes predicted in the C. elegans genome in combination with differential interference contrast time-lapse microscopy. Through systematic annotation of the resulting movies, we developed a phenotypic profiling system, which shows high correlation with cellular processes and biochemical pathways, thus enabling us to predict new functions for previously uncharacterized genes.

Animals↗
PubMed2005

[Potentials and limitations of stem cell therapy in myocardial disease].

Acute myocardial infarction (MI) leads to myocardial necrosis and is, by nature, an irreversible injury. The major goal to reverse left ventricular remodeling would be the enhancement of regeneration of cardiac myocytes as well as the stimulation of neovascularization within the infarct area, by repopulation of the injured myocardium with healthy autologous cells. In March 2001, the first patient was treated with direct intracoronary administration of autologous mononuclear bone marrow cells after acute MI. As improvements in myocardial function and perfusion could be detected 3 months later without any complications - a study was initiated in Düsseldorf. Until now 40 patients have been investigated. After a three month follow-up period, significant improvements concerning myocardial function, perfusion and metabolism could be obtained. This therapeutical effect may be attributed to bone marrow cell-associated myocardial regeneration and neovascularization. These results demonstrate that functional and metabolic regeneration of infarcted myocardium can be safely realized in humans by bone marrow mononuclear cell transplantation.

Bone Marrow Transplantation↗
PubMed2001

[ Update 2001. Myocarditis--cardiomyopathy].

Myocarditis is a common cardiological disease. New molecular biological and immunohistological methods have confirmed the persistence of viral infection and chronic myocardial inflammation in a considerable number of patients. A causal link between viral myocarditis and the development of dilated cardiomyopathy has been recognized. This has prognostic implications and helps for the decision of a specific immunosuppressive, immunomodulatory and antiviral therapy.

Antihypertensive Agents↗
PubMed2001

[Intracoronary, human autologous stem cell transplantation for myocardial regeneration following myocardial infarction].

OBJECTIVE: The regenerative potential of human autologous adult stem cells on myocardial regeneration and neovascularisation after myocardial infarction may contribute to healing of the infarction area. But no clinical application has previously been reported. We here describe for the first time the results of this method applied in a patient who had sustained an acute myocardial infarction. HISTORY AND CLINICAL FINDINGS: 14 hours after the onset of left precordial pain a 46-year-old man was admitted to our hospital for interventional diagnosis and treatment. Coronary angiography demonstrated occlusion of the anterior descending branch of the left coronary artery with transmural infarction. This was treated by percutaneous transluminal catheter angioplasty and stent placement. THERAPY AND RESULTS: Mononuclear bone marrow cells of the patient were prepared and 6 days after infaction 1,2 infinity 107 cells were transplanted at low pressure via a percutaneous transluminal catheter placed in the infarct-related artery. Before and 10 weeks after this procedure left ventricular function, infarct size, ventricular geometry and myocardial perfusion were measured by (201)thallium SPECT both at rest and on exercise, together with bull's-eye analysis, dobutamine stress echocardiography, right heart catheterisation and radionuclide ventriculography. At 10 weeks after the stem cell transplantation the transmural infarct area had been reduced from 24.6 % to 15.7 % of left ventricular circumference, while ejection fraction, cardiac index and stroke volume had increased by 20-30 %. On exercise the end diastolic volume had decreased by 30 % and there was a comparable fall in left ventricular filling pressure (mean pulmonary capillary pressure). CONCLUSION: These results for the first time demonstrate that selective intracoronary transplantation of human autologous adult stem cells is possible under clinical conditions and that it can lead to regeneration of the myocardial scar after transmural infarction. The therapeutic effects may be ascribed to stem cell-associated myocardial regeneration and neovascularisation.

Angioplasty, Balloon, Coronary↗
PubMed2000

Functional genomic analysis of cell division in C. elegans using RNAi of genes on chromosome III.

Genome sequencing projects generate a wealth of information; however, the ultimate goal of such projects is to accelerate the identification of the biological function of genes. This creates a need for comprehensive studies to fill the gap between sequence and function. Here we report the results of a functional genomic screen to identify genes required for cell division in Caenorhabditis elegans. We inhibited the expression of approximately 96% of the approximately 2,300 predicted open reading frames on chromosome III using RNA-mediated interference (RNAi). By using an in vivo time-lapse differential interference contrast microscopy assay, we identified 133 genes (approximately 6%) necessary for distinct cellular processes in early embryos. Our results indicate that these genes represent most of the genes on chromosome III that are required for proper cell division in C. elegans embryos. The complete data set, including sample time-lapse recordings, has been deposited in an open access database. We found that approximately 47% of the genes associated with a differential interference contrast phenotype have clear orthologues in other eukaryotes, indicating that this screen provides putative gene functions for other species as well.

Animals↗
PubMed2000

Repair of coronary arterioles after treatment with perindopril in hypertensive heart disease.

In hypertensive heart disease, no data are available on the repair of coronary resistance vessels in patients after long-term ACE inhibitor treatment. Fourteen patients with essential hypertension were studied with coronary flow reserve and with transvenous endomyocardial biopsy before and after 12 months of antihypertensive treatment with perindopril (4 to 8 mg/d, mean 5.9+/-2.3 mg/d). Left ventricular muscle mass index decreased by 11% (from 145+/-41 to 128+/-36 g/m(2), P=0.04). Maximal coronary blood flow was increased by 54% (from 170+/-46 to 263+/-142 mL. min(-1). 100 g(-1), P=0.001), and minimal coronary vascular resistance was diminished by 33% (from 0.67+/-0.21 to 0.45+/-0.19 mm Hg. min. 100 g. mL(-1), P=0.001); consequently, coronary reserve increased by 67% from 2.1+/-0.6 to 3. 5+/-1.9 (P=0.001). Structural analysis revealed regression of periarteriolar collagen area by 54% (from 558+/-270 to 260+/-173 microm(2), P=0.04) and of total interstitial collagen volume density by 22% (from 5.5+/-3.8 Vv% to 4.3+/-3.2 Vv%, P=0.04), whereas arteriolar wall area was slightly but not significantly reduced. Long-term therapy with the ACE inhibitor perindopril induces structural repair of coronary arterioles that is mainly characterized by the regression of periarteriolar fibrosis and associated with a marked improvement in coronary reserve. These findings indicate the beneficial reparative effects of ACE inhibition on coronary microcirculation in hypertensive heart disease.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

Immunogenicity of herpes simplex virus type 1 mutants containing deletions in one or more alpha-genes: ICP4, ICP27, ICP22, and ICP0.

Replication defective mutants of HSV have been proposed both as vaccine candidates and as vehicles for gene therapy because of their inability to produce infectious progeny. The immunogenicity of these HSV replication mutants, at both qualitative and quantitative levels, will directly determine their effectiveness for either of these applications. We have previously reported (Brehm et al., J. Virol., 71, 3534, 1997) that a replication defective mutant of HSV-1, which expresses a substantial level of viral genes without producing virus particles, is as efficient as wild-type HSV-1 in eliciting an HSV-specific cytotoxic T-lymphocyte (CTL) response. In this report, we have further evaluated the immunogenic potential of HSV-1-derived replication defective mutants by examining the generation of HSV-specific CTL following immunization with viruses that are severely restricted in viral gene expression due to mutations in one or more HSV alpha genes (ICP4, ICP27, ICP22, and ICP0). To measure the CTL responses induced by the HSV alpha-mutants, we have targeted two H-2Kb-restricted CTL epitopes: an epitope in a virion protein, gB (498-505), and an epitope in a nonvirion protein, ribonucleotide reductase (RR1 822-829). The HSV mutants used in this study are impaired in their ability to express gB while a majority of them still express RR1. Our findings demonstrate that a single immunization with these mutants is able to generate a strong CTL response not only to RR1 822-829, but also to gB498-505 despite their inability to express wild-type levels of gB. Furthermore, a single immunization with any individual mutant can also provide immune protection against HSV challenge. These results suggest that mutants which are restricted in gene expression may be used as effective immunogens in vivo.

Animals↗
PubMed1999

Activated Borna disease virus in affective disorders.

BACKGROUND: Borna disease virus (BDV) is an animal pathogen that causes behavioral changes in animals. Previous studies have found a high prevalence of serum antibodies as well as Borna disease viral antigens (BDVAGs) and RNA in the white blood cells of psychiatric patients, especially those with affective disorders. The present study attempts to offer a better description of the BDVAG cohort using clinical parameters. METHODS: The prevalence of BDVAG was examined in the peripheral mononuclear leukocytes of patients with a major depressive episode. A subgroup of patients underwent further clinical analysis. RESULTS: In this pilot study, at least, there was a significant difference in the prevalence of BDVAG between psychiatric inpatients with a major depressive episode and control individuals. It also appeared that BDVAG is more frequent in patients with recurrent major depression or bipolar disorder than in those with any other psychiatric disorder studied. The number of previous depressive episodes, as well as symptoms involving fatigue and concentration difficulties were positively related to BDVAG. CONCLUSIONS: The high rate of BDVAG, especially in fatigued patients with recurrent major depression or bipolar disorder, may be a nonspecific aspect of immunosuppression. The question remains whether this neurotropic virus may contribute to the pathogenesis of some types of affective disorder.

Adult↗
PubMed1998

A molecular basis for how a single TCR interfaces multiple ligands.

CD8+ T cells respond to Ags when their clonotypic receptor, the TCR, recognizes nonself peptides displayed by MHC class I molecules. The TCR/ligand interactions are degenerate because, in its life time, the TCR interacts with self MHC class I-self peptide complexes during ontogeny and with self class I complexed with nonself peptides to initiate Ag-specific responses. Additionally, the same TCR has the potential to interact with nonself class I complexed with nonself peptides. How a single TCR interfaces multiple ligands remains unclear. Combinatorial synthetic peptide libraries provide a powerful tool to elucidate the rules that dictate how a single TCR engages multiple ligands. Such libraries were used to probe the requirements for TCR recognition by cloned CD8+ T cells directed against Ags presented by H-2Kb class I molecules. When H-2Kb contact residues were examined, position 3 of the peptides proved more critical than the dominant carboxyl-terminal anchor residue. Thus, secondary anchor residues can play a dominant role in determining the antigenicity of the epitope presented by class I molecules. When the four solvent-exposed potential TCR contact residues were examined, only one or two of these positions required structurally similar residues. Considerable structural variability was tolerated at the remaining two or three solvent-exposed residues of the Kb-binding peptides. The TCR, therefore, requires close physico-chemical complementarity with only a few amino acid residues, thus explaining why TCR/MHC interactions are of low affinity and degenerate.

Amino Acid Sequence↗
PubMed1996

Differentiated HL-60 cells as model system for toxicity studies of inhalable dusts.

For the assessment of the toxicity of inhalable dusts, generally either in vivo investigations or tests with cultures of freshly isolated macrophages are used. In the present study, a calcitriol-treated HL-60 tumor cell line was investigated as an alternative model and compared with bovine alveolar macrophages. In both systems, upon exposure to two different quartz fractions, the amount and reaction pattern of superoxide anion release (O2.-) were determined by lucigenin-enhanced chemiluminescence; viability of cells was determined using the fluorescein diacetate-ethidium bromide assay. Nearly equal results were obtained in both systems, recommending the differentiated HL-60 cell line as an easily manageable model system for toxicity studies of particulate bronchopulmonary noxious agents, especially with regard to the lower experimental expenditure.

Animals↗
PubMed1996

Quantification of reactive oxygen species generated by alveolar macrophages using lucigenin-enhanced chemiluminescence--methodical aspects.

Alveolar macrophages lavaged from bovine lungs using Ca2(+)- and Mg2(+)-deprived saline containing EGTA for calcium chelation were cultivated in RPMI-1640 medium. The generation of reactive oxygen species (ROS) was assessed by determination of lucigenin-enhanced chemiluminescence (LUC-CL) using a LB 9505 C Biolumat. Monitoring of LUC-CL depends on various methodical parameters: besides medium constituents, the method of cell harvesting and the time-schedule of the protocol appear to be essential parameters that influence ROS-generation. In addition, the cell number (cell density) as well as the ratio of cell number to particle mass influence the amount of ROS-generation. Following exposure of cells to micronized quartz, we observed a dose-related increase in the generation of ROS.

Acridines↗