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Biomedical subjects

D Krause

Publications and source records attributed to D Krause.

At least 145 records · Page 8Linked to original sources
PubMed1989

Cloning of murine gelsolin and its regulation during differentiation of embryonal carcinoma cells.

The regulation of gelsolin levels during differentiation of the murine embryonal carcinoma cell line, PC-13, was investigated using nucleic acid and immunological probes. A cDNA clone, Mu-319, which contained the entire coding sequence for the cytoplasmic form of murine gelsolin was isolated using a polyclonal antibody. Gelsolin was detected in several cell lines but was not detectable in three undifferentiated embryonal carcinoma cell lines. Levels of gelsolin mRNA increased 10-fold during the differentiation of the murine embryonal carcinoma cell line, PC-13. Differentiation of PC-13 was accompanied by changes in cell shape, from small indistinct cells to large flat cells. The accumulation of gelsolin mRNA in PC-13 cells began 12-24 h after addition of the differentiation-inducing agents. In comparison, 2-5A-dependent RNase activity showed a 40-fold increase beginning after 24 to 36 h and c-fos mRNA were shown to increase about 9-fold beginning 36 to 60 h after induction of differentiation. The levels of gelsolin per se, as determined by immunoreactivity were also shown to increase with differentiation of PC-13 cells. These results suggest that gelsolin may play a role in the restructuring of actin filaments which accompanies the dramatic changes in cell shape during differentiation.

Amino Acid Sequence↗
PubMed1988

Immunochemical and immunocytochemical characterization of a novel monoclonal antibody recognizing a 140 kDa protein in cerebral pericytes of the rat.

A monoclonal antibody that recognizes a 140 kDa peripheral plasma membrane protein in pericytes of nervous tissues of the rat is described. Microvessels of brain cortex and perineurium of peripheral nerves are shown to react positively to this antibody. The antigen is absent in brain regions that lack a blood-brain barrier, i.e., choroid plexuses and area postrema. Antigen expression starts as early as day 18 of embryonic development. By means of immunoelectron microscopy the 140 kDa antigen was detected as clusters along the entire circumference of cerebral pericytes. The same antigenic determinant is also expressed in apical domains of plasma membranes of a variety of transporting epithelia, such as hepatocytes, enterocytes of the small intestine, and epithelial cells of proximal tubules of the kidney. We postulate the 140 kDa protein as being a constituent of the pericytes involved in regulative functions of the blood-brain barrier.

Animals↗
PubMed1988

Forskolin effects on the voltage-gated K+ conductance of human T cells.

Forskolin, a direct activator of adenylate cyclase, modifies the voltage-dependent K+ conductance of quiescent human peripheral blood T lymphocytes. In the presence of greater than 20 microM forskolin, the average voltage-gated current in whole-cell patch clamp is significantly decreased. The voltage dependence and kinetics of activation are not changed from untreated control cells. However, inactivation becomes biphasic. Much of the current inactivates very quickly (complete in 10 ms), and the remaining outward current inactivates more slowly with a time constant closer to that of control cells. To determine whether this effect is mediated by a rise in intracellular cAMP, cells were preincubated and subsequently voltage-clamped in the presence of other agents that raise the cAMP levels in T cells (isoproterenol plus a phosphodiesterase inhibitor, or dibutyryl cAMP) with no effect on the K+ conductance. Similarly, cells put in whole-cell patch clamp with cAMP, GTP, ATP, and theophylline added to the electrode filling solution showed no change in K+ current. Because other procedures that raise cAMP did not duplicate the effect of forskolin, we investigated the effect of 1,9-dideoxyforskolin, an analogue of forskolin that does not stimulate adenylate cyclase in human lymphocytes. This drug induced changes in the whole-cell K+ conductance identical to those observed with forskolin. Both forskolin and dideoxyforskolin inhibit mitogen-induced proliferation of lymphocytes. Because inhibition of proliferation occurs in the presence of known K+ channel blockers, these results suggest that forskolin has an effect on T cell mitogenesis that is mediated by inhibition of K+ conductance and is independent of cAMP.

Adenylyl Cyclases↗
PubMed1988

[Spinal changes in artistic gymnasts].

36 former competitive artistic women gymnasts and 10 general women gymnasts were examined after at least three years following their withdrawal from sports, for any pathological changes in their vertebral column. Anamnesis revealed that 64% of the artistic gymnasts complained of back pain during competitive sports, and even after having given it up there were still 61% complaining. X-ray film showed degenerative changes of the vertebral bodies and the intervertebral joints in 51.4%. Incidence of spondylolysis was 31.4% and hence two and a half times above that among the normal population. In 22 cases where x-ray films were available from the time they had been active, we found an increase rate of 36.4% in respect of spondylolysis, a worsening of scoliosis by 22.7% and an increase in degenerative changes at the minor vertebral joints by 31.8%.

Adult↗
PubMed1987

Lipid changes of astrocytes from mouse cerebellum cultured in lipid-free chemically defined medium and in serum-supplemented medium.

Astrocytes of mouse cerebellum were grown in chemically defined medium for 14 days, subcultivated and grown in serum-containing medium for up to 14 days. After 14 days in defined medium the cells showed fatty degeneration from which they recovered histologically and chemically after one week in serum-supplemented medium. At this point 99% of the cells were glial fibrillary acidic protein-positive and synthesized phosphatidylinositol, phosphatidylserine and bis(monoacylglycero)phosphate besides other phospholipids.

Animals↗
PubMed1987

Involvement of the 2'-5' A pathway in the augmentation of natural killer activity.

Pretreatment of human large granular lymphocytes (LGL) or unseparated peripheral blood mononuclear cells with interferon (IFN) resulted in a significant augmentation of natural killer (NK) activity. This increase was paralleled by an increase in the 2'-5'A synthetase activity. In order to investigate the possibility that IFN might be inducing augmentation of NK cells via the 2'-5'A pathway, we tested the effects of nonphosphorylated core material [(A2'p)2A] and of the triphosphorylated form of the 2'-5'A [ppp(A2'p)2A]. The core material had no detectable effect on NK activity. In contrast, when experiments were performed with the triphosphorylated form of 2'-5'A, NK activity was stimulated. In order to achieve activation, permeabilization of LGL with calcium chloride was necessary and, under these conditions, a dose-dependent augmentation of NK activity was seen. However, the calcium treatment had considerable toxic effects on basal levels of NK activity. Collectively, these results suggest that IFN may be inducing augmentation of NK activity via the 2'-5'A pathway. Further studies will be necessary to determine the effects of IFN and/or 2'-5'A on subsequent activation steps in the process leading to cytotoxicity by NK cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1987

[Practicality of ultrasound diagnosis in veterinary andrology].

It is possible to use the ultrasound technique in the veterinary andrology. Important results of that method may increase the evidence of the clinical examination of the male genital organs. To make sure that no harm may effect the sperm cells, ejaculates of bulls and boars were exposed to pulsed ultrasound (5 MHz/0,140 mW) up to 120 minutes. It was confirmed that this technique has no influence on sperm cell motility and morphology.

Animals↗
PubMed1986

Activation of 2-5A-dependent RNase by analogs of 2-5A (5'-O-triphosphoryladenylyl(2'----5')adenylyl(2'----5')adenosine ) using 2',5'-tetraadenylate (core)-cellulose.

A variety of 2-5A (px(A2'p)nA; x = 2 or 3, n greater than or equal to 2) analogs were assayed for their abilities to activate murine 2-5A-dependent RNase (subsequently "the nuclease") using a recently developed method. This technique consists of immobilizing and partially purifying the nuclease using core-cellulose [A2'p)3A-cellulose) and then monitoring the breakdown of poly(U)-3'-[32P]Cp into acid-soluble fragments. Several 5'-adenosinecapped analogs of 2-5A (containing a tetra-, tri-, or diphosphate) were analyzed, and it was found that reducing the number of phosphoryl groups between the 5' to 5'-diadenosine linkages resulted in a progressive loss of activity. Because A5' pppp(A2'p)3A was a potent activator of the nuclease yet stable during the assay these results suggested that a free 5'-phosphoryl group may not be required for the activation of the nuclease. A number of 8-bromoadenosine-substituted analogs of 2-5A were also studied. Curiously, the brominations decreased the activities of the 5'-di- and triphosphorylated molecules while substantially increasing the activities of the 5'-monophosphorylated species. The results indicated that a tri- or diphosphate moiety on the 5'-end of 2-5A or the presence of ATP is not absolutely required for the nuclease to be active. Furthermore, the ATP analog, beta, gamma-methylene ATP, did not inhibit the activity of the nuclease. Finally, a 3',5'-phosphodiester linkage isomer of 2-5A and a 3'-deoxy (cordycepin) analog of 2-5A were tested, and both were found to be completely without activity.

Adenine Nucleotides↗
PubMed1986

Voltage-gated potassium conductance in human T lymphocytes stimulated with phorbol ester.

The whole-cell patch-clamp method was used to study the voltage-gated K+ conductance of human peripheral blood T lymphocytes. After entry into whole-cell recording mode, there are time-dependent changes in some properties of the conductance. Over the first 10-30 min, the threshold for activation shifts about 10 mV more negative, and the rates of activation and inactivation increase. Inactivation is less strongly voltage dependent than activation or deactivation. Lymphocytes were stimulated to proliferate in culture with the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). No changes in K+ conductance were observed in the first few hours of TPA stimulation. At 24 h after mitogen addition, TPA-treated cells were found to have 1.7-fold greater average voltage-gated K+ conductance than unstimulated control cells. At 48 h, TPA-stimulated cells had the same average K+ conductance as at 24 h, even though the cells were now much increased in size, as measured by cell capacitance. DNA synthesis by cultures stimulated with TPA, phytohaemagglutinin or succinyl concanavalin A was depressed by the addition of 0.1 mM-quinine at any point in the culture period. In the first 20 h after mitogen addition, DNA synthesis was more effectively inhibited by quinine than if the drug were added later. Cell proliferation was equally sensitive to quinine regardless of mitogen.

Action Potentials↗
PubMed1986

Soft cervical disc herniations.

The authors report their findings in a series of 51 patients suffering from typical cervical radiculopathy. With the aid of the CT scanner and intravenous injection of a contrast medium, the quality and resolution of the resulting images allowed neurosurgical intervention in 42 patients in whom the symptomatology alone was not sufficiently informative to allow successful treatment. In most cases the CT images allowed an accurate diagnosis and revealed a free fragment that had torn the common posterior vertebra ligament.

Adult↗
PubMed1985

Independent regulation of ppp(A2'p)nA-dependent RNase in NIH 3T3, clone 1 cells by growth arrest and interferon treatment.

The regulation of ppp(A2'p)nA-(2-5A)-dependent RNase (RNase L or RNase F) was investigated in NIH 3T3, clone 1 cells using 2-5A-binding and nuclease activity assays. Minimal levels of 2-5A-dependent RNase were detected in actively dividing clone 1 cells; these levels were independently induced by growth arrest or interferon treatment. Accordingly, levels of the RNase were enhanced during growth arrest by confluency regardless of the presence or absence of interferon or antibody to interferon in the media. Measurement of 2-5A-dependent RNase was unaffected by the addition of any of six different proteinase inhibitors to the cells prior to extraction. The expression of 2-5A-dependent RNase in growth-arrested, interferon-treated cells was still relatively low (about one-third to one-half of that found in similarly treated murine Ehrlich ascites tumor cells). Although this amount of 2-5A-dependent RNase could not be detected by 2-5A-mediated ribosomal RNA cleavage, the activity was identified using a more sensitive novel assay for 2-5A-dependent RNase. In addition, introduction of 2-5A or poly(I) X poly(C) into growth-arrested, interferon-treated cells resulted in some inhibition of protein synthesis. The results indicated that the expression of 2-5A-dependent RNase in NIH 3T3, clone 1 cells is regulated under different physiological conditions and that low levels of 2-5A-dependent RNase were insufficient to significantly inhibit encephalomyocarditis virus replication.

Adenine Nucleotides↗