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Biomedical subjects

E Kremer

Publications and source records attributed to E Kremer.

26 records · Page 2Linked to original sources
PubMed1991

Fragile X genotype characterized by an unstable region of DNA.

DNA sequences have been located at the fragile X site by in situ hybridization and by the mapping of breakpoints in two somatic cell hybrids that were constructed to break at the fragile site. These hybrids were found to have breakpoints in a common 5-kilobase Eco RI restriction fragment. When this fragment was used as a probe on the chromosomal DNA of normal and fragile X genotype individuals, alterations in the mobility of the sequences detected by the probe were found only in fragile X genotype DNA. These sequences were of an increased size in all fragile X individuals and varied within families, indicating that the region was unstable. This probe provides a means with which to analyze fragile X pedigrees and is a diagnostic reagent for the fragile X genotype.

Chromosome Mapping↗
PubMed1991

Fragile X syndrome: genetic localisation by linkage mapping of two microsatellite repeats FRAXAC1 and FRAXAC2 which immediately flank the fragile site.

We report the genetic localisation of the fragile site at Xq27.3 associated with fragile X syndrome. The position of the fragile site within the multipoint linkage map was determined using two polymorphic microsatellite AC repeat markers FRAXAC1 and FRAXAC2. These markers were physically located within 10 kilobases and on either side of the p(CCG)n repeat responsible for the fragile site. FRAXAC1 has five alleles with heterozygosity of 44% and is in strong linkage disequilibrium with FRAXAC2 which has eight alleles and a heterozygosity of 71%. No recombination was observed either between these markers in 40 normal CEPH pedigrees or with the fragile X in affected pedigrees. These markers provide the means for accurate diagnosis of the fragile X genotype in families by rapid polymerase chain reaction analysis and were used to position the fragile X within the multipoint map of the X chromosome to a position 3.7 cM distal to DXS297 and 1.2 cM proximal to DXS296.

Base Sequence↗
PubMed1990

Isolation of a genomic clone encoding the rat histone variant, H1d.

Mammals contain a family of five closely related H1 histone variants (H1a-e) as well as two less closely related forms, H10 and H1t. We have sequenced a rat genomic clone that encodes one of the standard H1 variants. An RNA transcript of the gene was made with bacteriophage SP6 RNA polymerase and translated in a cell-free system. The protein synthesized in vitro was identified as variant H1d by its electrophoretic mobility.

Amino Acid Sequence↗
PubMed1986

Influence of ADP, blood flow velocity, and vessel diameter on the laser-induced thrombus formation.

The laser-induced thrombus model in rat mesenteric arterioles and venules represents a reliable and reproducible in vivo method. It is suitable for basic investigations concerning factors involved in thrombus formation as well as for testing antithrombotic effects of drugs. The laser-induced thrombus formation depends significantly on the presence of ADP, as ADP-utilizing enzymes inhibit thrombosis in the animal model. The instrumental test set-up consists of a 4 W Argon laser (Spectra Physics, Mountain View, CA, USA), a ray adaptation and adjusting device (BTG, Munich, FRG), a microscope (ICM 405, Zeiss, Oberkochen, FRG), and a video system (Sony, Japan). RBC velocity data were recorded with the help of a modified dual-slit technique (acc. to Wayland and Johnson). Results were expressed as number of laser injuries necessary to produce a defined thrombus (minimum size: 1/4 of the vessel diameter) under constant conditions (effective capacity: 30 mW, exposure time: 1/5 sec). The number of laser lesions necessary to induce a defined thrombus decreased with an increase in arteriole diameter (10 to 20 micron) but increased again in larger arterioles and small arteries (greater than 25 micron). On the arteriolar side there are significant correlation coefficients between vessel diameter and RBC velocity (r = 0.69), vessel diameter and No. of laser injuries (r = 0.70), and RBC velocity and No. of laser injuries (r = 0.71). Due to relative low flow conditions in the venules, the number of laser injuries required to induce a defined thrombus does not significantly depend on the vessel diameter.

Adenosine Diphosphate↗
PubMed1986

Effects of propentofylline (HWA 285) on laser-induced thrombus formation in healthy and diseased rat mesenteric arterioles.

The antithrombotic effects of the xanthine derivative propentofylline (HWA 285) were investigated in the laser-induced thrombus model in healthy and diseased rat mesenteric arterioles. Laser-induced platelet thrombi were documented by the help of an intravital microscope and a video system. The statistical comparison of drug-treated and untreated animals, in respect to the number of laser shots necessary to induce a defined thrombus, served as a quantitative measure for a potential antithrombotic drug effect. Propentofylline and acetylsalicylic acid, in single dosages of 10 and 30 mg/kg orally, significantly increased the number of laser shots required to produce a defined thrombus. Moreover, the drug decreased the laser-induced thrombus formation in a chronic experiment in adjuvant arthritic rats. After oral administration of 30 mg/kg for 21 days, propentofylline and pentoxifylline reduced significantly the thrombus formation, whereas acetylsalicylic acid exerted no effect.

Animals↗
PubMed1978

Nephroptosis and kidney function.

We have investigated the influence of renal mobility on both renal blood flow and glomerular filtration, in order to evaluate its role as a potential intermediate cause of hypertension. In 25 untreated patients we compared between recumbent and upright position the relative change in the following five parameters: effective renal plasma flow (ERPF), glomerular filtration rate (GFR), renal mobility, peripheral plasma renin activity (PRA) and blood pressure. We found a positive correlation between the degree of renal mobility and an observed decrease in ERPF. On the other hand, no relation was found between the former and an observed decrease in GFR. The PRA appeared to rise following the decrease of the ERPF. These observations suggest that renal mobility adds to the orthostatic reduction in renal blood flow.

Adult↗
PubMedDate not supplied

Effects of different mediators or cytokines and monoclonal antibodies to adhesion molecules on leukocyte adhesion in rat mesenteric venules.

Leukocyte adhesion (LA) to the endothelium of postcapillary venules is considered to be an important step in the inflammatory response. The recruitment of blood leukocytes into sites of inflammation involves a well-coordinated and dynamic sequence of events in which several cellular adhesion molecules (CAMs) and chemotactic cytokines play an active role. The aim of the present study was to elucidate receptor-mediated interaction in mesenteric venules of leukocyte rolling/adhesion and plasma leakage. We applied intravital microscopic techniques, with the help of an analogous video image processing system, to measure changes in the microvascular integrity. Rat monoclonal antibodies (MoAb) to different CAMs were administered before inflammatory stimuli were applied. Topical application of different doses of either lipo-polysaccharide (LPS), fMet-Leu-Phe, zymosan, complement C5a, Tnf-alpha, interleukin-1beta (IL-1beta), IL2 or IL-6 resulted in a dose-dependent increase in LA. The injection of a MoAb (1 mg/kg), 15 min prior to the LPS challenge, resulted in (1) total inhibition of LA, when MoAb to rat L-section, LFA1-beta and VLA-4 were used, (2) a moderate effect with LFA-1beta and Mac-1 MoAb, and (3) only a weak influence on LA by the MoAb to rat ICAM-1 (1 mg/kg). No effects were seen with IgG1 control MoAb. LA in acute models of inflammation can be regarded as a consequence of time-dependent differential effects of CAMs, as observed through the application of different MoAb.

Animals↗