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M Ahrens

Publications and source records attributed to M Ahrens.

At least 19 recordsLinked to original sources
PubMed1999

Apolipoprotein E (ApoE), a Bmp-2 (bone morphogenetic protein) upregulated gene in mesenchymal progenitors (C3H10T1/2), is highly expressed in murine embryonic development.

Apolipoprotein E (ApoE) was identified as upregulated by Bmp-2 (bone morphogenetic protein-2) in the murine mesenchymal progenitor cell line C3H10T1/2 by a subtractive cloning strategy. Expression of recombinant Bmps in mesenchymal C3H10T1/2 progenitors results in the differentiation into the osteogenic, the chondrogenic, and the adipogenic lineage. In addition, ApoE is also expressed in primary osteoblasts isolated from murine calvariae late in the in vitro osteoblast developmental sequence. To infer possible roles of ApoE in organogenesis and tissue differentiation, ApoE expression during mouse embryonic development was analyzed in murine midgestation and late embryonic development by in situ hybridization. ApoE is highly expressed at many sites of organ development (liver, brain, heart, eye, lung), probably in a subset of neural crest cells and ectodermal derivatives suggestive for important functions of ApoE during embryonic differentiation and organ development.

Animals↗
PubMed1999

Developmental expression analysis of murine autotaxin (ATX).

The murine homologue of the human motility-stimulating protein autotaxin (ATX) was identified as a BMP2 upregulated gene by subtractive cloning from mesenchymal progenitors C3H10T1/2 (Bächner, D., Ahrens, M., Betat, N., Schröder, D., Hoffmann. A., Lauber, J., Steinert, P., Flohe, L., Gross, G., 1998. Bmp-2 downstream targets in mesenchymal development identified by subtractive cloning from recombinant mesenchymal progenitors (C3H10T1/2). Dev. Dyn. 213, 398-411). ATX mRNA transcription is induced during BMP2 mediated osteo-/chondrogenic differentiation in vitro several orders of magnitude. To delineate a potential role for ATX in osteo-/chondrogenic development, its expression pattern during murine embryogenesis was examined in comparison with Col1a1 and Col2a1, a marker either of osteoblast, odontoblast and tendon or of chondrocyte development, respectively. Localization of murine ATX was first observed in the floor plate of the neural tube at day 9.5 of mouse embryonic development. Later, enhanced ATX expression levels were observed in proliferating subepithelial mesenchyme, during osteo-/chondrogenic and tooth development, in choroid plexus epithelium, in late kidney development, and in smooth muscles of the ductus deferens and the bladder.

Animals↗
PubMed1998

Bmp-2 downstream targets in mesenchymal development identified by subtractive cloning from recombinant mesenchymal progenitors (C3H10T1/2).

ABmp-dependent in vitro model was used to identify cDNAs during the manifestation of mesenchymal lineages. This model involves the recombinant expression of Bmps (Bmp-2, Bmp-4-7) in murine mesenchymal C3H10T1/2 progenitors, which leads to the differentiation into three lineages: the osteogenic, the chondrogenic and the adipogenic lineage, albeit in varying efficiencies. By subtractive cloning, 21 Bmp-2-regulated cDNAs from C3H10T1/2 mesenchymal progenitors were identified; 20 were related to known sequences and 1 was not. During mouse embryonic development, many of these cDNAs are expressed in chondrogenic, osteogenic, and in adipogenic tissues. Novel findings include a G0/G1 switch gene (G0S2), which was demonstrated to be predominantly expressed in adipose tissue during late murine embryonic development. Furthermore, the membrane-standing glycoprotein autotaxin (ATX) is expressed, at precartilage condensations, joint regions, and during tooth development. An as yet undescribed cDNA, 29A, which encodes a putative secreted factor, is expressed in developing osteo-/chondrogenic tissues of vertebrae, ribs, tooth, and the limb bud. C3H10T1/2-progenitors, therefore, may serve as a legitimate model for the investigation of the Bmp-mediated events during mesenchymal differentiation.

Amino Acid Sequence↗
PubMed1997

cDNA and deduced polypeptide sequence of a mouse selenoprotein P.

An 11-day embryonic Swiss Webster/NIH mouse cDNA library was screened with a partial murine selenoprotein P cDNA probe and a murine selenoprotein-P-type cDNA clone of 2075 bp length was obtained. The clone contained a 5'-leader sequence of 132 bp length, the selenoprotein P coding frame, and 803 base pairs in the 3' untranslated region. Alignment and RNA folding studies revealed the presence of two well conserved selenocysteine inserting motifs in the 3' flanking region. The deduced polypeptide sequence comprises 380 residues including ten selenocysteines. Identical amino acid residues in homologous positions are 86%, 71%, and 64% when compared to the previously reported selenoprotein P sequences of rat, man, and cattle, respectively. The comparatively low similarity between the selenoprotein P sequences reported so far leaves open the question whether they belong to the same molecular clade.

Amino Acid Sequence↗
PubMed1997

A technique of chronic intravascular catheterization for monitoring haemodynamic and laboratory values in conscious swine.

In human and small animal intensive care medicine percutaneous sheath introducer (PSI) sets are commonly used for repeated insertion of an arterial or a venous catheter with only one vascular puncture. We used PSI for chronic catheterization of swine with a Swan-Ganz thermodilution catheter via a surgically exposed external jugular vein. In this way we were able to change defective catheters or correct the position of the catheter tip without renewed surgical intervention.

Animals↗
PubMed1997

Parathyroid hormone enhances early and suppresses late stages of osteogenic and chondrogenic development in a BMP-dependent mesenchymal differentiation system (C3H10T1/2).

The role of parathyroid hormone (PTH) upon osteo-/chondrogenic development was investigated in a bone morphogenetic protein (BMP)-dependent differentiation system involving the recombinant expression of BMPs in mesenchymal progenitor cells (C3H10T1/2). The constitutive expression of the PTH/PTH related protein receptor in this system led to a marked stimulation of chondrogenic and osteogenic development, while the permanent application of the ligand PTH(1-34) resulted in opposite responses by stimulating the early and suppressing the late stages of osteo-/chondrogenic development. These contrasting effects of PTH(1-34) on osteogenic and chondrocytic development seem, therefore, to depend on the cellular state of differentiation. The osteogenic and chondrocytic differentiation potential was substantiated histologically and by genetic analyses of marker genes like c-fos, alkaline phosphatase, osteocalcin, collagen alpha1(I), and collagen alpha1(II). The capacity to regulate osteogenic and chondrogenic development is located in the amino-terminal (1-34) region of the PTH molecule and seems to be mediated by the cyclic adenosine monophosphate signaling cascade. The application of other PTH domains like PTH(28-48) and PTH(53-84) did not exhibit significant responses. PTH acts as an essential factor in mesenchymal development controlling rates of differentiation into the osteogenic or chondrogenic lineage. The analysis of PTH effects in this system demonstrates the value of recombinant mesenchymal progenitor cells in the in vitro analysis of osteo-/chondrogenic development.

Bone Morphogenetic Proteins↗
PubMed1996

Effects of the Pringle maneuver on hemodynamics during laparoscopic liver resection in the pig.

The Pringle maneuver (PM) is recognized in conventional liver surgery as a method of controlling bleeding. To determine the hemodynamic effects of the PM during pneumoperitoneum (PP) for laparoscopic liver resection, we measure hemodynamic and blood gas changes in 7 healthy pigs. All variables were recorded 5 min before and 10 and 30 min after employing PP or PM and 10 min after discontinuation of PM. After the induction of PP, cardiac index and arterial carbon dioxide tension significantly increased, accompanied by a significant decrease in pH. After the beginning of PM, cardiac index and mean arterial and central venous pressures decreased significantly, whereas the heart rate rose markedly. After discontinuation of the PM, the systemic vascular resistance index decreased, and the heart rate remained elevated. These results demonstrate severe hemodynamic deterioration with PP and a subsequent PM. The latter should, therefore, be considered only as a last resort for the control of bleeding during laparoscopic liver surgery.

Animals↗
PubMed1995

Genetic services for familial cancer patients: a survey of National Cancer Institute cancer centers.

In the past decade, significant progress has been made in understanding the genetic component of familial cancers. Genes associated with familial colon and breast cancers have recently been isolated and molecular diagnostic tests are expected to become available in the near future. Clinicians now have the opportunity to recognize and counsel individuals with elevated risk of cancer by identifying risk factors and genes associated with cancer predisposition. The rapid advances in molecular technology are a direct challenge to the medical community and cancer centers to supply specialized clinical services for familial cancers. We sought to ascertain the activities of cancer centers in the development of programs and the provision of genetic services for familial cancer. We surveyed 41 centers with National Cancer Institute (NCI) cancer center support grants. One half of the centers responding (17 of 34) reported that they provide some genetic services for familial cancer. About one half of these 17 centers (eight [57%] of 14; the three remaining clinics that responded had incomplete information on this indicator) see a variety of patient types on a small scale (fewer than 100 patients per year), and most provide four basic clinical evaluations: medical evaluation, cancer risk assessment, genetic counseling, and pedigree analysis. Staffing of each center varied widely, as did the types of screening services offered (including molecular diagnostic testing). Several centers (six [35%] of 17) indicated that they were in the developmental stages for serving familial cancer patients, and many seem to be increasing their activities in this area. The remaining 17 NCI-supported centers that responded, however, currently provide no genetic services for familial cancers. The results of this survey suggest that there is interest in developing clinical programs for familial cancers by NCI-supported cancer centers, but most of these programs are in developmental stages. A base line has been established to monitor future progress for the provision of cancer genetic services.

Cancer Care Facilities↗
PubMed1994

Antigen heterogeneity among isolates of Mycoplasma bovis is generated by high-frequency variation of diverse membrane surface proteins.

The protein and antigen profiles of 11 isolates of Mycoplasma bovis were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis of whole organisms. The isolates examined included the type strain PG45 and 10 other filter-cloned strains or purified isolates both from animals without clinical signs and from clinical cases of bovine mastitis, arthritis, or pneumonia. While the overall protein patterns visualized by silver staining were very similar, marked differences in the antigen banding profiles were detected by rabbit antiserum prepared against whole organisms from one of the strains analyzed. This antigenic heterogeneity was shown to be independent of the geographical origin, the type of clinical disease, and the site of isolation and was also observed among serial isolates from a single animal. Antigen profiles were further monitored throughout sequentially subcloned populations of the PG45 strain. This clonal analysis revealed a high-frequency variation in the expression levels of several prominent antigens. All of these variable antigens were defined by detergent-phase fractionation with Triton X-114 as amphiphilic integral membrane proteins. A subset of different-sized membrane proteins was identified by a monoclonal antibody raised against a PG45 subclone expressing a 63- and a 46-kDa variant antigen within that set. The selective susceptibility of these proteins to trypsin treatment of intact organisms and their ability to bind the monoclonal antibody in colony immunoblots demonstrated that they were exposed on the cell surface. In addition, their preferential recognition by serum antibodies from individual cattle with naturally induced M. bovis mastitis or arthritis confirmed that they were major immunogens of this organism. These studies establish that the apparent antigenic heterogeneity among M. bovis isolates reported here does not represent stable phenotypic strain differences generated from accumulated mutational events but reflects distinct expression patterns of diverse, highly variable membrane surface proteins.

Animals↗
PubMed1993

Expression of human bone morphogenetic proteins-2 or -4 in murine mesenchymal progenitor C3H10T1/2 cells induces differentiation into distinct mesenchymal cell lineages.

The cDNAs encoding the human bone morphogenetic proteins BMP-2 and BMP-4 in an eukaryotic expression vector were permanently transferred into the murine mesenchymal progenitor cell line C3H10T1/2. Originally, these cells are known to differentiate into myotubes, adipocytes, and chondrocytes upon the addition of azacytidine. Permanent transfection of genes encoding human BMP-2 and BMP-4 induces differentiation into the osteogenic lineage. The osteogenic differentiation potential of C3H10T1/2 cells is substantiated by histochemical and genetic analyses of marker genes typical or specific for osteogenesis, including the parathyroid hormone receptor, alkaline phosphatase, osteopontin, osteonectin, and osteocalcin. In addition to osteoblast formation, development into adipocytes and chondrocytes is also observed, suggesting that BMP-2 and BMP-4 induce differentiation into three mesenchymal lineages.

Adipocytes↗
PubMed1981

[Studies on differences in the preventive effects of habitual physical activity in occupation versus leisure time. II. Effects of physical activity in occupation versus leisure time on physical working capacity (author's transl)].

One hundred and twenty men, aged 23--60 years and having various professions participated in studies on relationships between daily physical activity and physical performance capacity (PPC). The determination of daily physical activity at work and of the habitual leisure time activities has been described earlier (Ilmarinen et al. 1980). The determination of physical performance capacity was based on W170, W85% and on predicted VO2 max measured with continuously increasing work load on a bicycle ergometer. The W85% modification corresponds to the working capacity at a heart rate level of 85% of maximal heart rate. Workers with a combination of heavy physical work and active leisure time showed systematically the highest absolute and relative values of PPC. However, although the results indicated that the effect of work activity on PPC was not significant, the effects of leisure time activities on W85% and on VO2 max related to lean body mass were significant. It is concluded that the leisure time sport activities are more important than the physical activity at work in maintaining or increasing the PPC. Aerobic sport activities in leisure time are recommended both for persons with physically heavy and light work.

Adult↗
PubMed1978

[The effect of an on the job training program -- stairclimbing -- on the physical working capacity of employees (author's transl)].

Following medical screening and physical fitness testing (W170) 52 voltuntary employees in a 31-story administration building were formed into matched pairs and randomly allocated into intervention (stairclimbing) and control (lift) groups. The intervention group was asked to climb at least 25 floors/workday or 125 floors/week. the control group was asked to use only the lift. The intervention time was 10 weeks. The physiological measurements were made before and after the intervention. The number of stairs climbed was recorded daily in a diary. The heart rate was recorded continuously over one workday before and during the interventions. The average quantity of training in the final intervention group (n = 19) was 29.9 floors/workday or 36,790 kpm/week and in the control group 4.6 and 5980 correspondingly. The average training frequency was 4.3 in intervention and 1.4 climbs/workday in the control group. The average number of continuous floors used during climbing was 7.0 in intervention and 3.4 in control group. The average number of minutes on heart rate level of 130-159 beats/min during one workday was 7.8 in intervention and 1.6 in control group. The W170 (W/kg) increased 17.8% and the predicted VO2max (ml/min/kg) 15.1% in intervention group. The difference between the intervention group and the control group was significant (p less than 0.01). It was concluded, that stairclimbing is a suitable on the job physical activity program for middle-aged, untrained men.

Employment↗
PubMed1978

Some observations on ocular manifestation of sickle cell disease.

The ocular manifestations of 76 sickle cell disease patients are reported. Our findings indicate that any type of sickle cell oculopathy may appear in conjunction with any type of hemoglobinopathy and that no single ocular finding is specific to any one type of sickle cell anomaly. Sickle cell oculopathy, particularly retinopathy, is found to be a slowly progressive condition. Treatment of retinal and vitreal neovascularization with photocoagulation seems to be indicated to stop the disease process. Acute retinal vascular occlusion seems to respond favorably to the intravenous administration of low molecular weight dextran and papaverine hydrochloride. Sickle cell patients suffering from retinal detachment do not respond favorably to conventional retinal detachment surgery.

Adult↗
PubMed1977

Effect of heparin modification on its activity in enhancing the inhibition of thrombin by antithrombin III.

Studies were conducted to determine the effect of modifying specific functional groups of heparin on its antithrombin III-enhancing activity. The derivatives employed were heparin methyl ester, heparinylglycine and N-desulfated heparin. The carboxyl-modified derivatives increase the rate of inhibition of thrombin by antithrombin III, although not to the same extent as heparin. N-Desulfated heparin is devoid of any activity. Heparin methyl ester is more potent than heparinylglycine in activating antithrombin III, as exhibited by its immediate effect on the thrombin-fibrinogen reaction. However, heparinylglycine is the more effective of the two, in increasing the rate of thrombin deactivation by antithrombin III. The results indicate that although free carboxyl groups of heparin are not crucial for its binding to antithrombin III, they are important for the combination of the latter with thromobin. In contrast, N-sulfates are critical for the interaction of heparin with antithrombin III.

Animals↗
PubMed1977

[Studies on the success of insemination after various insemination dates in biotechnical puberty induction of young sows].

Different frequencies and periods of insemination were checked with the view to optimising puberty induction to young sows, for which purpose 500 IU PMS/250 IU HCG were injected to 571 animals in seven experiments. Insemination was carried out by deadline, since follicle stimulation was exhibited by almost all animals following the above treatment, while only some of them displayed tolerance. Advantage was taken of the induced oestrus, since its ovulation rates were higher than those associated with subsequent heat cycles, and because a synchronised second oestrus was recordable only from some of those animals which exhibited follicle stimulation in response to puberty induction. The most favourable results in terms of pregnancy and number of embryoes, against the background of the great variability in ovulation onset, were obtained, if insemination was applied 72, 96, and 120 hours after gonadotrophin treatment. From among the variants with two inseminations, good results were obtained from those 96 and 120 hours after PMS/HCG treatment.

Animals↗
PubMed1977

[Studies on various dosages of PMS and HCG in biotechnical puberty induction in young sows].

The PMS and HCG doses by which to induce puberty and successfully use the first induced oestrus were tested in three experimental slaughter series on 197 prepuberal young sows. An injection of 500 International Units of PMS and 250 IU of HCG was found to bear greatest promise. While higher dosages gave higher rates of ovulation and, following insemination, higher numbers of embryos, pregnancy rates as a whole dropped severely. Since a very high percentage of all animals involved exhibited follicle stimulation, following such treatment, while only half of them displayed tolerance, it is strongly suggested to use for all animals deadline-oriented rather than toleranceoriented insemination.

Animals↗