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Biomedical subjects

C Friedrich

Publications and source records attributed to C Friedrich.

At least 37 records · Page 2Linked to original sources
PubMed1999

[The costs of hip-fracture in Germany: a prospective evaluation].

OBJECTIVE: To assess the direct and indirect costs of hip fracture in dependence of postoperative care setting. STUDY DESIGN: Prospective cohort study. METHODS: 227 consecutive patients in three hospitals (city, town, and small town) presenting with hip fracture. For 177 patients there was follow-up regarding post-operative care-setting. During follow-up the cost of the remaining patient at 1, 3, 6 month were recorded and afterwards adjusted to the distribution of the initial cohort. To obtain information on patient characteristics, assessment during hospital stay and follow up have been performed. RESULTS: There was a relevant difference in costs depending on the care setting after hip fracture. The nursing home - nursing home, community - community, and community - nursing home resulted in total costs at 6 month of 17,701 DM, 27,102 DM and 54, 503 DM, respectively (average: 24,508 DM). Nursing home costs contributed significantly to the differences between groups. Valid and predictive measures could not be established in first analysis of performed assessments. CONCLUSION: Due to the high incidence of hip fractures (100,000/y) indirect costs play a major role in the economic impact of this illness. The analysis of the effectiveness of interventions has to take into account these costs to achieve adequate conclusions.

Aged↗
PubMed1999

Ikaros sets thresholds for T cell activation and regulates chromosome propagation.

T cell activation involves the sustained accumulation of T cell receptor (TCR) and IL-2 receptor (IL-2R) mediated signaling events that promote cell cycle entry and progression. The Ikaros family of nuclear factors regulate this process by providing thresholds overcome by receptor signaling. T cells with reduced levels of Ikaros activity require fewer TCR engagement events for activation, exhibit a greater proliferative response to IL-2, and are less sensitive to inhibitors of TCR and IL-2R signaling. Upon T cell activation, Ikaros proteins localize in a higher-order chromatin structure where they colocalize with components of the DNA replication machinery. Proliferating T cells with reduced Ikaros activity display chromosome abnormalities. We propose that participation of Ikaros in higher-order chromatin structures controls cell cycle transitions and restricts DNA replication.

Animals↗
PubMed1999

Salt-resistant alpha-helical cationic antimicrobial peptides.

Analogues based on the insect cecropin-bee melittin hybrid peptide (CEME) were studied and analyzed for activity and salt resistance. The new variants were designed to have an increase in amphipathic alpha-helical content (CP29 and CP26) and in overall positive charge (CP26). The alpha-helicity of these peptides was demonstrated by circular dichroism spectroscopy in the presence of liposomes. CP29 was shown to have activity against gram-negative bacteria that was similar to or better than those of the parent peptides, and CP26 had similar activity. CP29 had cytoplasmic membrane permeabilization activity, as assessed by the unmasking of cytoplasmic beta-galactosidase, similar to that of CEME and its more positively charged derivative named CEMA, whereas CP26 was substantially less effective. The activity of the peptides was not greatly attenuated by an uncoupler of membrane potential, carbonyl cyanide-m-chlorophenylhydrazone. The tryptophan residue in position 2 was shown to be necessary for interaction with cell membranes, as demonstrated by a complete lack of activity in the peptide CP208. Peptides CP29, CEME, and CEMA were resistant to antagonism by 0.1 to 0.3 M NaCl; however, CP26 was resistant to antagonism only by up to 160 mM NaCl. The peptides were generally more antagonized by 3 and 5 mM Mg2+ and by the polyanion alginate. It appeared that the positively charged C terminus in CP26 altered its ability to permeabilize the cytoplasmic membrane of Escherichia coli, although CP26 maintained its ability to kill gram-negative bacteria. These peptides are potential candidates for future therapeutic drugs.

Alginates↗
PubMed1999

The unidirectional valve is the best method to determine maximal inspiratory pressure during weaning.

OBJECTIVES: Although maximal inspiratory pressure (MIP) is used as an index of inspiratory muscular strength, there is no consensus on how to measure it. We compared, during weaning from mechanical ventilation, two methods of measurement to determine which shows the greater values (MIPbest) and is more reproducible. One method measured MIP when negative pressure was maintained for at least 1 s after a forceful expiration, and the other method measured MIP with a unidirectional expiratory valve (MIPuni). DESIGN: The study had a crossover design, and patients randomly performed three measurements of each method (t1). The procedure was repeated by the same observer after 20 min (t2). The maximal value in each method was considered. SETTING: ICU, Hospital A.C. Camargo, São Paulo, Brazil. PATIENTS: Fifty-four consecutive patients undergoing short-term mechanical ventilation who became eligible for the study when their physicians decided to restore spontaneous breathing. RESULTS: MIPbest values were arrived at using MIPuni 75% of the time either in tl or t2. MIPuni yielded a higher average of MIPbest values in t1 and t2 (p < 0.0001). The effort-to-effort coefficient of variation of one method compared with the other during t1 and t2 was similar (p > 0.2 for t1; p > 0.8 for t2). Also, when comparing tl and t2, the coefficients of variation were similar for each method (p > 0.62). CONCLUSIONS: Because MIPuni displayed the maximal values, it is the best method for estimating MIP in patients undergoing short-term mechanical ventilation. The reproducibility of consecutive measurements was similar between the methods, even after a short period of time.

Adult↗
PubMed1999

[The private institute of Franz Wilhelm Schweigger-Seidel (1795-1838) in Halle].

The aim of this paper is to describe the development of the chemical-pharmacist institute of Franz Wilhelm Schweigger-Seidel (1795-1838) in Halle. The institute was founded in 1829. Six letters by Johann Salomo Christoph Schweigger (1779-1857) and Franz Wilhelm Schweigger-Seidel to Johann Bartholomäus Trommsdorff (1770-1837) present new detailed information on the institute of Schweigger-Seidel and on his biography, especially on his descent and on his work as a pharmacist. Besides it was possible to show the family links between him and J. S. Chr. Schweigger resulting from adoptation in a correct way for the first time.

Germany↗
PubMed1998

Continuous biological waste gas treatment in stirred trickle-bed reactor with discontinuous removal of biomass.

A new reactor for biological waste gas treatment was developed to eliminate continuous solvents from waste gases. A trickle-bed reactor was chosen with discontinuous movement of the packed bed and intermittent percolation. The reactor was operated with toluene as the solvent and an optimum average biomass concentration of between 5 and 30 kg dry cell weight per cubic meter packed bed (m3pb). This biomass concentration resulted in a high volumetric degradation rate. Reduction of surplus biomass by stirring and trickling caused a prolonged service life and prevented clogging of the trickle bed and a pressure drop increase. The pressure drop after biomass reduction was almost identical to the theoretical pressure drop as calculated for the irregular packed bed without biomass. The reduction in biomass and intermittent percolation of mineral medium resulted in high volumetric degradation rates of about 100 g of toluene m-3pb h-1 at a load of 150 g of toluene m-3pb h-1. Such a removal rate with a trickle-bed reactor was not reported before.

Air Pollutants↗
PubMed1998

Ikaros in hemopoietic lineage determination and homeostasis.

Studies on the molecular mechanisms that control hemopoietic differentiation have focused on signaling cascades and nuclear effectors that drive this complex developmental system in a regulated fashion. Here we review the role of Ikaros, the founding member of a unique family of zinc finger transcription factors in this developmental process. Studies on an Ikaros null mutation have revealed an essential role for this factor in lymphoid cell fate determination and at subsequent branch points of the T cell differentiation pathway. Differences in the phenotypes of a null and a dominant negative (DN) Ikaros mutation provide insight into a regulatory network through which Ikaros proteins exert their effects in development. In addition a comparative analysis of the hemopoietic stem cell and precursor compartment resulting from the two Ikaros mutations reveals a profound yet not absolute requirement for Ikaros in the production and differentiation of these populations.

Animals↗
PubMed1998

Aiolos regulates B cell activation and maturation to effector state.

Aiolos encodes a zinc finger DNA-binding protein that is highly expressed in mature B cells and is homologous to Ikaros. In the periphery of mice homozygous for an Aiolos-null mutation, B cells exhibit an activated cell surface phenotype and undergo augmented antigen receptor (BCR)-mediated in vitro proliferative responses, even at limiting amounts of stimulant. In vivo, T cell-dependent B cell responses, including the formation of germinal centers and elevated serum IgG and IgE, are detected in Aiolos-deficient mice in the absence of immunization. Auto-antibodies and development of B cell lymphomas are frequently seen among aging Aiolos mutants. In sharp contrast to conventional B cells, B cells of the peritoneum, of the marginal zone, and the recirculating bone marrow population are greatly reduced.

Animals↗
PubMed1998

Identification of distinct elements of the stromal microenvironment that control human hematopoietic stem/progenitor cell growth and differentiation.

Using a novel collection of conditionally immortalized mouse stromal cell clones, we evaluated the role of distinct elements of the hematopoietic microenvironment in supporting and regulating the growth, division, and differentiation of a candidate human stem cell population (CD34+/CD38-). We found functional diversity in the capacity of different stromal cell clones to support the growth of primitive (CD34+/CD38-) and committed (CD34+/CD38+) hematopoietic progenitors and their differentiation into mature hematopoietic cells (CD34-/CD45+). Among the stromal cell clones that supported long-term hematopoiesis, we identified two clones that induced expansion of CD34+ progenitor/stem cells during the first 4 weeks of coculture and that supported the maintenance of this CD34+ population for up to 10 weeks in vitro. However, these two clones appeared to represent two different microenvironments with regard to the signals they provide to the different CD34+ progenitor subpopulations: One stromal clone preserved a pool of undifferentiated, relatively quiescent (CD34+/CD38-) progenitor cells, allowing their differentiation at a low rate into more committed (CD34+/CD38+) progenitors; the other fostered a more extensive and rapid differentiation of all CD34+/CD38- progenitors into CD34+/CD38+ cells, preferentially maintaining this committed population at a higher rate of cell division. These stromal cell clones were also able to support the proliferation and differentiation of CD34+/CD38- cells in conditions in which progenitor-stroma contact was prevented. This collection of stromal cell clones may represent a unique tool for the study of stromal regulators of hematopoiesis as well as for the support of gene transfer into hematopoietic progenitor cells.

Animals↗
PubMed1998

[Pyrethroids in house dust of the German housing population--results of 2 nationwide cross-sectional studies].

As a part of the German Environmental Surveys performed in 1985/86 (West Germany), 1990/91 (West Germany) and 1991/92 (East Germany), dust samples were collected in the households of about 1600 randomly selected adults (25 to 69 years) and an analysis of these samples was performed in respect of their content of 8 different pyrethroids and of the synergist piperonyl butoxide (PBO). In the 1990-92 survey about 90% of the samples contained permethrin in concentrations above the limit of quantification. This showed permethrin to be the most widespread of the 8 compounds investigated. The geometric mean of the permethrin content in domestic dust was 0.22 mg/kg. Only about 8% of the samples contained one or more of the other investigated substances (cyfluthrin, lambda-cyhalothrin, cypermethrin, alpha-cypermethrin, deltamethrin, empenthrin, d-phenothrin) in quantifiable amounts. About 76% of the samples contained quantifiable amounts of PBO. In East Germany the geometric mean of the PBO content (0.21 mg/kg) was significantly higher than in West Germany (0.07 mg/kg), but no difference for permethrin was found. Significant associations could be shown for the permethrin content and the application of biocides as well as for the PBO content and regional factors (size of community, type of dwelling area). Samples collected in 1985/86 (West Germany) showed a geometric mean for permethrin of 0.06 mg/kg and for PBO of 0.07 mg/kg. Comparing the values of 1985/86 and 1990/91, a significant increase can be observed for permethrin, whereas the PBO concentration remained constant.

Adult↗
PubMed1998

Attempt to differentiate between individual glutathione peroxidases in biological samples.

Routine determinations of glutathione peroxidases (GPx) still suffer from poor standardization and usually from lack of specification. The different types of glutathione peroxidases present in cellular homogenates may be differentially estimated by their distinct substrate specificities. Complex lipid hydroperoxides required for this approach, however, are not generally available nor easily standardized due to their molecular heterogeneity and tendency to form micelles. We therefore developed a simple procedure for the differential estimation of the major cellular types of GPx, the cytosolic GPx (cGPx) and the phospholipid hydroperoxide glutathione peroxidase (PHGPx) taking advantage of the peculiar susceptibility of PHGPx to deoxycholate. It proved to reliably determine the activities of both purified cGPx and PHGPx, in mixtures thereof, and in homogenates of tissue samples (e.g., testes), and some (e.g. ECV 304) but not all (e.g. THP-1) cultured cell lines. The method allows the differential estimation of cGPx and PHGPx, if the samples do not contain further types of GPx.

Animals↗
PubMed1998

[Kastner and Trommsdorff].

The aim of this paper is to demonstrate the connection between Karl Wilhelm Gottlob Kastner (1783-1857) and Johann Bartholomäus Trommsdorff (1770-1837). Kastner was the teacher of Justus Liebig (1803-1873) in Bonn and Erlangen. The correspondence, which includes unpublished letters from Kastner to Trommsdorff, presents a wealth of detailed information for the biographies of Kastner and Trommsdorff.

Germany↗
PubMed1998

[Zurich physician-pharmacist family Lavater and Johann Wolfgang von Goethe].

The aim of this paper is to demonstrate the connections between Johann Wolfgang von Goethe (1749-1832) and the physician and pharmacist family Lavater in Zurich. The analysis of the correspondence between Johann Bartholomäus Trommsdorff (1770-1837) and the Lavater family and between the Lavater family and the government of the duchy of Weimar shows an interesting story about a picture "Goethe in Italy".

Correspondence as Topic↗
PubMed1997

S-100 protein and neuron-specific enolase concentrations in blood as indicators of infarction volume and prognosis in acute ischemic stroke.

BACKGROUND AND PURPOSE: Better techniques are needed to monitor infarction volume and predict neurological outcome after ischemic brain infarction. We evaluated the usefulness of serial measurements of S-100 protein versus neuron-specific enolase (NSE) in blood samples from patients with acute stroke. METHODS: Using nonisotopic sandwich immunoassays, we measured plasma concentrations of S-100 protein and NSE on admission and on days 3, 4, 7, and 14 after infarction in 44 patients (age range, 22 to 86 years; mean age, 65.1 years; 12 female, 32 male). Infarct volume was measured by volumetric CT on day 4 after ictus, and clinical outcome was assessed at discharge from hospital with the Activities of Daily Living Scale and 6 months after infarction with the Glasgow Outcome Scale. RESULTS: Peak blood levels of S-100 protein were found on day 2.5 +/- 1.3, and peak levels of NSE were found on day 1.9 +/- 0.8 after infarction. Peak plasma levels of S-100 protein correlated well with infarct volume (r = .75, P < .001) and with clinical outcome assessed with the Glasgow Outcome Scale (r = .51, P < .001). Serum levels of NSE correlated with infarct volume (r = .37, P < .05) but not with clinical outcome (r = .18, P > .05). CONCLUSIONS: The results of our study indicate that measuring blood concentrations of S-100 protein periodically in the first 10 days after cerebral infarction helps to predict infarct volume and the long-term neurological outcome more accurately than periodic measurements of blood concentrations of NSE.

Activities of Daily Living↗
PubMed1996

Hematopoietic supportive functions of mouse bone marrow and fetal liver microenvironment: dissection of granulocyte, B-lymphocyte, and hematopoietic progenitor support at the stroma cell clone level.

We dissected the functions of the microenvironment of bone marrow (BM) and fetal liver (FL) at the cellular level by cloning individual stromal calls and characterizing their phenotypical and functional features. Stromal cell clones derived from FL are large in size (mean forward light scatter intensity [mFSC] of 450), express the surface antigen Thy-1 but not Sca-1 and 6 out of 6 are able to differentiate into fat accumulating adipocytes. BM derived stromal cell clones are either small (mFSC of 250) or large (mFSC of 450), express Sca-1 but not Thy-1 and only 2 out of 7 differentiate towards adipocytes. Heterogeneity in terms of vascular adhesion molecule-1, intracellular adhesion molecule-1 and heat stable antigen expression was found among the different cell clones. Functional assays using long- and short-term cocultures of stromal and hematopoietic calls revealed: (1) the capacity of 8 out of 12 stromal cell clones to support the expansion of primitive hematopoietic progenitors (colony forming unit spleen day 12) more than 10 weeks. Fat accumulation but not expression of stem cell factor by stromal cells did correlate with this supportive function. (2) Better support of granulocyte maturation and proliferation by BM- compared to FL-derived stromal cell clones. However, stromal cell clones from both organs expressed macrophage-colony stimulating factor. (3) The ability of 4 out of 12 stromal cell clones (derived from both, FL and BM) to support the expansion of Interleukin-7 dependent pre-B cells from the BM. Pre-B cell growth stimulating factor was not restricted to supporters. (4) Mutual exclusiveness of myeloid and lymphoid support in that a given stromal cell clone supported either pre B-cell or granulocyte expansion. Experiments comparing the support of BM- and FL-derived hematopoietic progenitors showed identical responses of late (B220+/c-kit-) but strikingly different responses of early (B220+/c-kit+) pre-B cells, revealing different proliferation requirements for FL- versus BM- derived early pre-B cells in vitro.

Adipose Tissue↗
PubMed1996

Vascular cell adhesion molecule-1 expression by hematopoiesis-supporting stromal cells is not essential for lymphoid or myeloid differentiation in vivo or in vitro.

Binding of myeloid and lymphoid precursors to stromal cells in bone marrow has been suggested to be mediated through alpha 4 integrins (alpha 4) and vascular cell adhesion molecule-1 (VCAM-1) expressed on hematopoietic progenitors and stromal cells, respectively. It has not been shown, however, how essential the VCAM-1/ alpha 4 interaction is for hematopoiesis in vivo and whether or not other adhesion pathways can provide similar functional binding between stromal cells and hematopoietic progenitors. We addressed this issue by analyzing myeloid and lymphoid differentiation in vivo in mice with VCAM-1-null or -hypomorphic mutations and in vitro in long-term hematopoietic cultures with stromal cell clones from wild-type mice, which express or do not express VCAM-1. Mice bearing VCAM-1 mutations had no gross hematopoietic insufficiencies in the myeloid or lymphoid compartments and the distribution of myeloid progenitors between bone marrow and periphery was normal. In Dexter type long-term bone marrow cultures from mutant mice, the formation of supportive stromal cell layers and myeloid proliferation and differentiation were not affected by the absence of VCAM-1. Long-term maintenance and proliferation of clonable pre-B cells, cobblestone formation and differentiation to IgM-secreting, mature B cells was equally possible on VCAM-1+ and VCAM-1- stromal cell clones. We conclude from our data that VCAM-1 is not essential for the functional interaction between hematopoietic progenitors and stromal cells required for myeloid and B-lymphoid development in vivo or in vitro.

Animals↗