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Biomedical subjects

D Krause

Publications and source records attributed to D Krause.

At least 19 recordsLinked to original sources
PubMed1992

Pattern of glucose transporter (Glut 1) expression in embryonic brains is related to maturation of blood-brain barrier tightness.

A constant supply of blood-borne glucose is vital to cerebral metabolism. Although transport of glucose into the nervous tissue, effectively separated from the blood by a functional barrier (the blood-brain barrier, BBB), is one of the essential properties of the cerebral endothelium, little is known about its metabolic regulation and developmental expression in the BBB. In this study we provide evidence by immunocytochemistry that the pattern of the brain endothelial glucose transporter in rat brains (BBB-GT), immunologically homologous with the human hepatoma (G2), human erythrocyte transporter (Glut 1), changes with BBB maturation. While the neuroepithelium at embryonic days 12 and 13 shows a high incidence of immuno-detectable BBB-GT, vascularisation of the cerebral anlage and subsequent development of vascular tightness, as evidenced by intravascularly applied horseradish peroxidase and fluorescinated dextrans, is accompanied by a significant reduction of BBB-GT expression in neuroepithelial cells and confinement of BBB-GT expression to the cerebral endothelium. Immunoblots and Northern blots of embryonic brain homogenates corroborate this change in BBB-GT expression in the brain anlage at the time of BBB maturation. However, low molecular weight glucose transporters, presumed to be of non-endothelial origin, are less dramatically reduced. The development of BBB tightness, therefore, seems to play a pivotal role in the pattern of BBB-GT expression during brain differentiation.

Animals↗
PubMed1992

Development of a sensitive peptidase assay: in search of cell associated proteases responsible for the cleavage of preproTGF alpha.

A radiometric assay has been developed for the detection of proteolytic activity capable of releasing transforming growth factor alpha (TGF alpha) from its membrane bound precursor. The assay is dependent upon the separation by thin layer chromatography of hydrolytic products of a nonapeptide substrate containing a radioactive iodinated tyrosine residue as a reporting group N-terminal to an octapeptide which is cognate to the N-terminal cleavage sequence of TGF alpha. We describe the selectivity of the peptidase assay with commercially purified proteases and with cell-associated peptidases, its exquisite sensitivity, and its applicability to defining peptidase activity, which may be responsible for the processing of the membrane-bound prepro TGF alpha. The activity of two different elastases had different profiles which thus may be of use in characterizing them. The characteristics of the intact and extracted HeLa cell assay with respect to time, cell density, and peptidase concentration are defined, as are conditions needed to remove endogenous, confounding, proteolytic activity from the serum used to support cell culture. Intact HeLa cell cultures exhibit both exo- and endo-peptidase activity at approximately equal levels in both sparse and dense monolayer culture without relationship to cell density, and at a level equal to 1-2% of total cell activity of these enzyme classes.

Amino Acid Sequence↗
PubMed1992

[Salvaging a mass grave from 1945--Lieberose Labor Camp of the Sachsenhausen concentration camp].

It is reported about a recovering a common grave of 577 skeletons from 1945. Investigations of the age of the victims, the cause of death etc. were carried out. There were gunshot fractures at 541 skeletons. In 93.7% out of all cases there were gunshot fractures of the skull and the cervical vertebra. Difficulties arose from root interpretations in addition to intertwinings owing to the location of the skeletons. Indications to belonging to nationality of the victims are discussed by means the results from AB0-analysis and denture works.

Burial↗
PubMed1992

Investigations on the rectal absorption of chloramphenicol in rabbits after tenside use.

The rectal dose of 16 mg.kg-1 b.w. chloramphenicol (1) without additional tensides did not result in any detectable absorption of effective substance. In contrast, 0.04% of the N-lauroylleucine tenside allowed a rectal absorption having the same effect as that of an injection of the same quantities of effective substance. The tenside efficiency was not influenced by varied suppository masses (gelatine or Rosupol U, respectively), or by the pH value of the suppositories. Different particle sizes (less than 40 microns or greater than or equal to 40 up to less than 400 microns) of 1 did not change the absorption rate (AUC0-5h) significantly, but did change the plasma concentration-time profile considerably.

Animals↗
PubMed1992

MRI of aggressive meningiomas.

The authors have attempted to establish by MRI morphological criteria for the so-called "aggressive" intracranial meningiomas. The MRI features of 20 meningiomas histologically aggressive (numerous mitoses and small necrotic foci) or malignant (same plus invasion of the subjacent brain tissue) were compared with those of a control population of 26 patients with benign meningioma. The site of the tumour and its histological type had little predictive value, but there was a remarkably high proportion of male patients in the group with aggressive meningioma (9/20 versus 2/26). More than other varieties, aggressive meningiomas frequently emitted, on both T1- and T2-weighted sequences, a heterogeneous signal due to a necrotic focus (P less than 0.01). The high-intensity signal observed on T2-weighted sequences (11/20) was suggestive of syncitial or angioblastic meningioma. Cystic meningiomas were present in virtually equal proportions (3/20 versus 3/26) in the two populations and could raise problems concerning the diagnosis of nature, especially when intraventricular. Gadolinium injection provided further evidence of aggressiveness, such as irregular tumour outline or even contrast enhancement of brain tissue in malignant cases (3/4), but enhancement of the dura mater was equally frequent in both groups (P greater than 0.2). Massive peritumoral oedema was significantly more frequent in aggressive melanomas (P less than 0.01).

Adolescent↗
PubMed1991

Effect of coherence time of the applied magnetic field on ornithine decarboxylase activity.

Skepticism over the possibility of weak electromagnetic fields affecting cell function exists because endogenous thermal noise fields are larger than those reported to cause effects. Four-hour exposure to a 55- or 65-Hz field approximately doubles the specific activity of ornithine decarboxylase (ODC) in L929 cells. To test the idea that the cell discriminates against this thermal noise because it is incoherent, partial incoherence was introduced into the applied field by shifting the frequency between 55- to 65-Hz at intervals of tau coh--delta tau where tau coh is a predetermined time interval and delta tau much less than tau coh varies randomly from one frequency shift to the next. To obtain the full ODC enhancement, coherence of the impressed signal must be maintained for a minimum of about 10s. For tau coh = 5.0s a partial enhancement is elicited, and at 1.0s there is no response. Unfortunately coherence times of this duration are too short to solve the thermal noise puzzle.

Animals↗
PubMed1991

Correlation of zonula occludens ZO-1 antigen expression and transendothelial resistance in porcine and rat cultured cerebral endothelial cells.

Cerebral endothelial cell cultures (CECC) have been utilized as an in vitro system for simulating the blood-brain barrier. We have studied the expression of a tight junction associated protein (ZO-1) concomitantly with measurements of transendothelial electrical resistance and freeze-fracturing to test the barrier properties of CECC monolayers and, thereby, their capability in serving as an in vitro blood-brain barrier model. Freshly isolated CECC aggregates and 7 day old CECCs in primary culture express the ZO-1 protein. Measurements of the transcellular resistance of CECC monolayers yielded an electrical resistance of about 90 omega cm2. The low electrical resistance of cerebral endothelial monolayers together with the reduced complexity of the tight junction complement in vitro are indicative of reduced barrier properties of the in vitro system.

Animals↗
PubMed1991

Subarachnoidal macrophages share a common epitope with resident non-cerebral macrophages and show receptor-mediated endocytosis of albumin-gold and IgG-gold complexes.

Cerebral macrophages are supposed to exploit a pivotal role in scavenger functions of the central nervous system. We have examined the in vivo uptake of serum albumin and IgG conjugated with colloidal gold by subarachnoidal macrophages. These serum-borne proteins are endocytosed by receptor-mediated endocytosis by varying kinetics. Albumin-gold conjugates were found to be associated to a significant amount with coated pits and coated vesicles 1 min after superfusion of the cerebral surface. Within 25 min the major fraction of albumin-gold was transferred to the lysosomal compartment. IgG-conjugates revealed a less pronounced uptake. The uptake of albumin-gold could be competed by saturating of the 'receptor sites' with free albumin. It is suggested that the described receptor-mediated uptake of serum-borne proteins by subarachnoidal macrophages serves a cleansing function following blood-brain barrier disruption during acute or subacute inflammatory reactions.

Animals↗
PubMed1991

Molecular anatomy of the blood-brain barrier as defined by immunocytochemistry.

This review outlines the recent developments and improvements of our knowledge concerning the molecular composition of the BBB as revealed by immunocytochemistry. Data have been accumulated which show that the BBB exhibits a specific collection of structural and metabolic properties which are also found in tight transporting epithelia. This conclusion is substantiated by (i) the implementation of antibodies which recognize proteins of non-BBB origin, to show that these biochemical markers and the functions that they represent are localized in the BBB endothelium; and (ii) the characterization of target molecules to which polyclonal or monoclonal antibodies which have been generated to epitopes of the BBB endothelium or brain homogenates. According to these data the protein assemblies comprising the phenotypical appearance of the BBB can therefore be defined by the particular selection as well as topological expression of common epithelial antigens, rather than the expression of BBB-unique molecular species. In this respect the immunocytochemical data corroborate the physiological assumption that the BBB possesses the character of a specific polarized epithelium. Attention is also given to the description of developmental expression of BBB-related immunomarkers. By collecting the data from different sources we introduce a classification of the BBB marker proteins according to their developmental appearance. Three groups of proteins are classified with respect to their sequential expression around the time of BBB closure: Phase E (early) markers which appear before BBB closure, phase I (intermediate) markers which are expressed at the time of BBB tightening, and phase L (late) markers which are detectable after the closure of the BBB. Such a scheme may to be useful in better defining the maturation process of BBB, which apparently is not a momentary event in brain development, but rather consists of a temporally sequenced process of hierarchically structured gene expression which finally define the molecular properties of the BBB. This process continues even after parturition, especially with regard to the achievement of immunological properties of the mature BBB. By examining the developmental spatio-temporal expression of different BBB markers we conclude that the mechanisms governing the pattern of BBB maturation are not limited to the interactions occurring between glial and endothelial cells. We therefore suggest a heuristic model in a triangular interrelationship that includes differentiation effects of neurons on glia and of glia cells on the BBB endothelium.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Magnetic resonance imaging in the diagnosis of pulmonary infarction.

We report for the first time, to our knowledge, MRI features which could differentiate noninvasively pulmonary infarction from pneumonia. Three subjects with angiographically proven pulmonary infarction showed high T1 weighted MRI signals located in the embolic territory. Three patients with pneumonia and one patient with emboli, but without infarction, did not have these T1 weighted images.

Diagnosis, Differential↗
PubMed1991

[Method of combined demonstration of Gc globulin, alpha-1-antitrypsin, erythrocyte acid phosphatase and phosphoglucomutase using isoelectric focusing in ultra-thin layer gels].

An economic and reliable method for simultaneous determination of Gc, alpha-1-antitrypsin, acid erythrocyte phosphatase, and phosphoglucomutase by means of isoelectric focussing in ultrathin-layer gels is described. Man advantages are time- and costsaving without any unreliabilities in forensic application.

Acid Phosphatase↗
PubMed1991

Microwave exposure alters the expression of 2-5A-dependent RNase.

The effects of 2.45-GHz continuous-wave microwaves (SAR = 130 mW/g) on the expression of the interferon-regulated enzymes 2'-5'-oligoadenylate (2-5A) synthetase(s) and 2-5A-dependent endoribonuclease (RNase L) were studied in murine L929 cells. Cells growing as monolayers were removed from the substratum and placed in suspension culture for a 4-h sham or microwave exposure. The cells were returned to monolayer growth for 18 h, and then harvested and assayed to determine the amount of RNase L protein (via [32P]2-5A binding) and the specific activities of RNase L and 2-5A synthetase. Binding of radioactive 2-5A to RNase L for sham- and microwave-exposed samples was 14.5 and 36.4% above control, respectively (the microwave-exposed bound 19.0% more probe than the sham-exposed). The increases in 2-5A binding were accompanied by corresponding elevations of RNase L specific activity. In contrast, sham or microwave irradiation produced no alterations in 2-5A synthetase specific activity. No detectable differences were noted in the postexposure cell viability, plating efficiency, or proliferation rate. Also, there were no detectable differences in cell viability or plating efficiency between controls and cultures irradiated for 2 h when the temperature was simultaneously increased to above normal physiological limits (39 to 45 degrees C). The SAR (130 mW/g) and the power density (95 mW/cm2) used for the greater part of this study were nearly 20 times higher than the ANSI limit of 8 mW/g and 5 mW/cm2 for any 1 g of exposed human tissue.

2',5'-Oligoadenylate Synthetase↗
PubMed1990

Determination of affinities of murine and chimeric anti alpha/beta-T-cell receptor antibodies by flow cytometry.

In this report we describe the use of a calibrated flow cytometer to quantify the expression of the human alpha/beta-T-cell-receptor on peripheral blood lymphocytes of healthy human blood donors and on the T-cell line HPB-ALL. To calculate the maximum of antibodies which are needed to obtain antigen saturation per cell and to determine the affinity of murine and chimeric anti-TCR antibodies, we applied Scatchard-plot and double reciprocal Klotz-plot analyses.

Animals↗
PubMed1990

[A comparison of intermittent compression with single and multi-chamber systems in treatment of secondary arm lymphedema following mastectomy].

In a comparative study 38 patients with secondary unilateral lymphatic oedema after mastectomy were investigated with regard to the efficacy of intermittent compression treatment using uni- or multichamber systems (Jobst and Lymph-a-mat respectively). Although both machines significantly reduce oedema, there is no difference between their reduction capacities.

Arm↗
PubMed1989

[Cimetidine and ethanol].

Cimetidine inhibits hepatic drug metabolism, but its effect on ethanol elimination is less well established. The influence of cimetidine on the kinetics of ethanol is studied with three standardized drinking experiments. Cimetidine had no influence on the absorption or elimination of ethanol. There were significant differences in distribution of ethanol in consequence of inhibition of vascular histamine receptors after cimetidine application.

Adolescent↗