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Biomedical subjects

C Weber

Publications and source records attributed to C Weber.

At least 217 records · Page 12Linked to original sources
PubMed1995

Docosahexaenoic acid selectively attenuates induction of vascular cell adhesion molecule-1 and subsequent monocytic cell adhesion to human endothelial cells stimulated by tumor necrosis factor-alpha.

Incorporation of the n-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) but not eicosapentaenoic acid or n-6 arachidonic acid into human umbilical vein endothelial cell (HUVEC) phospholipids dose-dependently reduced tumor necrosis factor-alpha (TNF-alpha)-induced surface expression of vascular cell adhesion molecule-1 (VCAM-1). In parallel, DHA inhibited TNF-alpha-stimulated monocytic U937 cell adhesion to HUVECs but did not affect TNF-alpha- or interferon gamma-induced expression of intercellular adhesion molecule-1 and endothelial leukocyte adhesion molecule-1 or VCAM-1 induction by interleukin-1 beta. DHA appeared to attenuate VCAM-1 transcription, as it reduced induction of VCAM-1 mRNA by TNF-alpha. VCAM-1 induction is regulated by activation of nuclear factor-kappa B, which can be mediated by a TNF-alpha-responsive phosphatidylcholine-specific phospholipase C (PC-PLC). Gel-shift analysis showed inhibition of TNF-alpha-induced nuclear factor-kappa B mobilization by DHA. While the PC-PLC inhibitor D609 dose-dependently prevented VCAM-1 induction by TNF-alpha, 1,2-diacyl-glycerol (DAG) stimulated VCAM-1 expression, suggesting that VCAM-1 induction by TNF-alpha may be mediated by activation of PC-PLC. Treatment with DHA resulted in a fourfold enrichment in PC. In addition, DHA or D609 but not eicosapentaenoic acid or arachidonic acid suppressed activation of PC-PLC by TNF-alpha, estimated as [14C]DAG synthesis in prelabeled HUVECs. Incorporation of DHA into phospholipids selectively attenuates VCAM-1 induction by TNF-alpha and subsequent monocytic cell adhesion by inhibition of TNF-alpha-stimulated PC-PLC activation in HUVECs.

Base Sequence↗
PubMed1995

Extracorporeal shock wave treatment raises blood pressure in borderline hypertensive rats.

The long-term sequelae on kidney function and blood pressure of renal shock wave treatment were studied in normotensive Wistar rats, contralaterally nephrectomized Wistar rats and borderline hypertensive F1-hybrids bred from stroke-prone spontaneously hypertensive rats and Wistar-Kyoto rats. Renal shock wave treatment raised arterial blood pressure in borderline hypertensive, but not in normotensive, rats. A concomitant impairment of ipsilateral renal function or perfusion was not seen despite macroscopic and microscopic evidence of a loss of functioning parenchyma. We conclude that extracorporeal shock wave treatment, by way of its detrimental effects on the kidney, has the potential to provoke arterial hypertension in rats, provided that a genetic predisposition exists.

Animals↗
PubMed1994

Selective solid-phase extraction of urinary 2,3-dinor-6-ketoprostaglandin F1 alpha for determination with radioimmunoassay.

This paper describes a method for selective two-step solid-phase extraction of urinary 2,3-dinor-6-ketoprostaglandin F1 alpha for reliable determination with radioimmunoassay. In the immunoreactivity profile of non-selectively extracted urine after HPLC separation, over 90% of the total 2,3-dinor-6-ketoprostaglandin F1 alpha immunoreactivity consisted of interfering material coeluting with 6-ketoprostaglandin F1 alpha and 2,3-dinor-6-ketoprostaglandin F1 alpha. Among the alkyl silica sorbents studied (methyl, butyl, octyl, and octadecyl), an efficient separation of 2,3-dinor-6-ketoprostaglandin F1 alpha from 6-ketoprostaglandin F1 alpha and the lowest immunoreactive concentration of analyte were achieved in extraction on the methyl silica sorbent by elution of 2,3-dinor-6-ketoprostaglandin F1 alpha with chloroform: hexane (85:15, v/v) from the cartridge. The proportion of specific immunoreactivity could be further increased by two-step extraction of sample on methyl silica cartridges, first at pH 3 and then at pH 10 using diethyl ether:hexane (85:15, v/v) and chloroform as eluent, respectively. After this, a high correlation was found with concentrations of samples determined by radioimmunoassay using three different antisera. A significant correlation of values was also observed between samples measured by radioimmunoassay and those measured by GC-MS. The values of 12-h excretion of 2,3-dinor-6-ketoprostaglandin F1 alpha in eight volunteers (268 +/- 204 ng/g creatinine, mean +/- SD) as well as the inhibitory effect of acetylsalicylic acid (74 +/- 12%) are in accordance with those reported in the literature. This selective extraction procedure provides a high validity in radioimmunoassay without requiring subsequent TLC or HPLC purification.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

High level expression in Escherichia coli and characterization of the EF-hand calcium-binding protein caltractin.

Caltractin is a member of the calmodulin superfamily of Ca(2+)-binding proteins that was originally cloned at the DNA level from the unicellular green alga Chlamydomonas reinhardtii. Human and mouse homologs to algal caltractin have been recently characterized. In the studies reported here, recombinant Chlamydomonas caltractin was expressed at high levels in Escherichia coli and purified to homogeneity. The use of the ompT-host BL21 proved critical for obtaining high yields of homogeneous full-length protein. Growth and purification protocols were optimized to allow reproducible and efficient production of tens of milligrams of pure protein from 1-liter cultures. Caltractin has a distinct UV spectrum which is largely dominated by the fine structure due to the 9 Phe residues. Unlike other members of the same protein family, the UV and the CD spectra do not change upon addition of Ca2+ to the apoprotein. However, the 1H NMR spectrum shows distinct changes upon Ca2+ binding, which are indicative of structural and/or dynamic changes largely reminiscent of other members of the calmodulin superfamily. Ca2+ binding measurements demonstrated the binding of four Ca2+ ions to caltractin with two higher affinity (Kd = 1.2 x 10(-6) M) and two lower affinity (Kd = 1.6 x 10(-4) M) sites. Caltractin is highly stable in both the apo- and the Ca(2+)-loaded states. The unusual stability of apocaltractin makes this protein highly suited for structural studies by multidimensional NMR aimed at understanding the structural and dynamic consequences of Ca2+ binding, and the molecular basis of Ca2+ signal transduction.

Amino Acid Sequence↗
PubMed1994

Differential expression of heat shock proteins in pancreatic carcinoma.

In the present study we sought to determine by Northern blot analysis and mRNA in situ hybridization whether gene expression of heat shock proteins (HSPs) (HSP 89 alpha, HSP 89 beta, HSP 70, and ubiquitin) is altered in pancreatic carcinoma, compared to control tissues (normal pancreas and chronic pancreatitis tissue). HSP 89 alpha was selectively overexpressed in pancreatic carcinoma, and tumor cells were shown to contain the largest amount of HSP 89 alpha mRNA. Steady state levels of HSP 70 mRNA were increased in pancreatic carcinoma (tumor and connective tissue cells) and in chronic pancreatitis (connective tissue cells and residues of exocrine acinar cells). HSP 89 beta and ubiquitin B were constitutively expressed at high levels in pancreatic tissue from all three groups; HSP 89 beta mRNA was found in cells of parenchymal and stromal origin. A strong correlation was found between the expression of HSP 70 and the expression of transforming growth factor beta 1. The finding that HSPs are differentially expressed in pancreatic cancer, compared to normal pancreas and chronic pancreatitis tissue, and the cancer specificity of HSP 89 alpha suggest that HSPs play a specific role in the pathogenesis of pancreatic cancer, e.g., by participating in regulatory processes or in tumor immunity, as proposed previously.

Blotting, Northern↗
PubMed1994

Distinct patterns of differentiation induced in the monocytic cell line Mono Mac 6.

The human Mono Mac 6 cell line exhibits many characteristics of mature blood monocytes including expression of the CD14 molecule and production of cytokines, such as interleukin-1 (IL-1), IL-6, and tumor necrosis factor. To determine whether these cells can be further differentiated, we treated the cells for up to 3 days with either prostaglandin E2 (PGE2; 10(-5) or 10(-6) M), lipopolysaccharide (LPS; 10-20 ng/ml), or tetradecanoylphorbol-13-acetate (TPA; 10-50 ng/ml). All three reagents reduced proliferation and expression of the early myelomonocytic antigen CD33, and all increased phagocytosis of staphylococci and constitutive expression of mRNA for the macrophage colony-stimulating factor (M-CSF) receptor. By contrast, with respect to CD23 (Fc epsilon RII) expression, CD14 expression, and production of O2-, the three reagents induced distinct responses. Expression of CD23 (Fc epsilon RII) on Mono Mac 6 cells (36%) was not increased by LPS and TPA but was increased by PGE2 treatment to 48%, with a 50% increase of fluorescence intensity. The CD14 antibody My4 stained more than 75% of untreated Mono Mac 6 cells with a specific mean fluorescence intensity of 87.5 channels. This staining was increased more than twofold by both PGE2 and LPS. Staining with the CD14 antibody UCHM1 (6%) was increased to 43% by PGE2 and to 43% by LPS. This increase in CD14 cell surface expression was accompanied by a rise in soluble CD14 and enhancement of CD14 mRNA. By contrast, TPA treatment resulted in a twofold decrease of CD14 cell surface staining with no significant change in sCD14, while CD14 mRNA was transiently down-regulated. Secretion of O2- (stimulated by TPA) was already detectable in untreated Mono Mac 6 cells (6.1 mmol/10(6) cells/30 min), and this response was enhanced 10-fold by pretreatment with LPS but not with PGE2 or TPA. The kinetics of M-CSF receptor mRNA, CD14 expression, and O2- production revealed that these monocytic features started to increase at 6-24 h and were maximal at 2 days. These data suggest that the three reagents induce maturation of the Mono Mac 6 cells to different levels or into different branches of the monocyte system with the notable differences that PGE2 enhances CD23 expression, LPS enhances O2- secretion, and TPA down-regulates CD14.

Antigens, CD↗
PubMed1994

Construction of a high-resolution linkage map for Xp22.1-p22.2 and refinement of the genetic localization of the Coffin-Lowry syndrome gene.

The genes responsible for two X-linked diseases, the Coffin-Lowry syndrome (CLS) and juvenile retinoschisis (RS), have been previously mapped, through linkage studies, to an 8-cM region, in Xp22.1-p22.2, flanked distally by two tightly linked markers, DXS207 and DXS43, and proximally by DXS274. In the present study, five Genethon markers have been assigned to the (DXS207, DXS43)-DXS274 interval using somatic cell hybrids and a meiotic breakpoint panel and ordered together with three markers previously mapped to this region. A genetic map, which includes 13 loci and spans a distance of approximately 13 cM, was derived from linkage analysis using the CEPH families. The most likely locus order and map distances (in centimorgans) are Xpter-DXS16-(3.4)-(DXS207, DXS43, DXS1053)-(2.0)-(DXS999, DXS257)-(1.7)-AFM291 wf5-(1.4) - DXS443 - (2.0) - (DXS1229, DXS365) - (2.1) - (DXS1052, DXS274, DXS41)-Xcen. Analysis of multiply informative crossovers established AFM291 wf5 and DXS1052 as new flanking markers for CLS, which significantly reduces the candidate region for this disease gene to a 4- to 5-cM interval. Three markers, DXS443, DXS1229, and DXS365, mapping within this interval showed complete cosegregation with the disease phenotype, giving a multipoint lod score of 14.2. The present map provides the framework for constructing a YAC contig for the CLS and RS region and should be useful for refining the localization of other disease genes mapping to this region. The panel of somatic cell hybrids characterized for the present study has also allowed us to refine the localization of five genes (CALB3, GRPR, PDHA1, GLRA2, and PHKA2) and two expressed sequence tags (DXS1118E and DXS1006E) previously assigned to the Xp22 region.

Abnormalities, Multiple↗
PubMed1994

Differential induction of eicosanoid synthesis in monocytic cells treated with retinoic acid and 1,25-dihydroxy-vitamin D3.

Synthesis and release of eicosanoids is characteristic to mature monocytes, while in undifferentiated premonocytic cells arachidonic acid (AA) metabolism is barely detectable. Since some vitamins and cytokines induce differentiation of these cells to a more monocyte-like cell type, we evaluated the effect of retinoic acid (RA), 1,25(OH)2-vitamin D3 (1,25-D3) and interferon-gamma (IFN-gamma) on AA metabolism in the human premonocytic cell lines U937 and THP-1. In U937 cells, differentiation with RA (1 microM) followed by stimulation with the calcium ionophore A23187 (10 microM) or platelet activating factor (PAF; 100 nM) significantly increased synthesis of immunoreactive 6-keto PGF1 alpha, TxB2 and PGE2 5- to 6-fold. Analysis of AA metabolism in RA-differentiated cells prelabelled with [3H]-AA revealed the formation of additional radioactive compounds which coeluted with standards for PGF2 alpha, PGD2 and 12-hydroxyheptadecatrienoic acid (HHT). The structural identity of 6-keto PGF1 alpha, TxB2, PGE2 and HHT was confirmed by gas chromatography-mass spectrometry (GC-MS). In parallel, RA induced the expression of the monocytic surface antigen CD11b, but not CD14. Differentiation with 1,25-D3 (10 nM) only marginally increased stimulated eicosanoid formation, while it more effectively induced expression of CD11b and CD14. Pretreatment with IFN-gamma (100 IU/ml) slightly increased stimulus-dependent AA metabolism, but did not induce expression of CD11b or CD14. Induction of eicosanoid synthesis by RA was further confirmed in THP-1 cells. These data indicate that RA most effectively induced cyclooxygenase activity and stimulus-dependent eicosanoid formation in U937 and THP-1 cells. Furthermore, since expression of monocytic surface antigens differed between RA and 1,25-D3, it is suggested that induction of cyclooxygenase activity may correlate to differentiation into distinct monocytic phenotypes.

Antigens, Surface↗
PubMed1994

Effect of dietary coenzyme Q10 as an antioxidant in human plasma.

A human study including 22 volunteers was conducted to investigate the antioxidative effect in blood of dietary coenzyme Q10 supplementation. The levels of alpha-tocopherol, ascorbic acid, lipid peroxidation (measured as TBARS) and the redox status of CoQ10 (reduced CoQ10/total CoQ10) were measured in plasma as markers for the antioxidative status once a week during the study period. To introduce an increased oxidative stress, a fish oil supplementation was given. The levels of alpha-tocopherol and ascorbic acid and the redox status did not change upon CoQ10 supplementation, while the level of TBARS decreased. The decrease in TBARS might be ascribed to an antioxidative effect of the supplied CoQ10. The constant redox level of CoQ10 during the CoQ10 supplementation shows that the exogenous CoQ10 is reduced during absorption and subsequent incorporation into lipoproteins, which is a prerequisite for its antioxidative function. The fish oil supplementation resulted in a higher TBARS level and a lower alpha-tocopherol level, but the redox level of CoQ10 was unchanged. In conclusion, the CoQ10 supplementation resulted in a higher plasma level of reduced CoQ10 and a lower TBARS level, but sparing of other plasma antioxidants (i.e. ascorbic acid and alpha-tocopherol) was not observed.

Administration, Oral↗
PubMed1994

Lovastatin inhibits receptor-stimulated Ca(2+)-influx in retinoic acid differentiated U937 and HL-60 cells.

Lovastatin was used to study the role of isoprenylated proteins on stimulus-induced increase of cytosolic Ca2+ in retinoic acid-differentiated U937 and HL-60 cells. Preincubation of the cells with lovastatin for 11-24 h reduced the Ca(2+)-influx induced by PAF of FMLP. The maximal decrease was 60% in U937 cells and 40% in HL-60 cells. The ID50s of lovastatin in U937 and HL-60 cells were 5 microM and 15 microM, respectively. Lovastatin did not inhibit Ca(2+)-discharge from intracellular stores. Addition of mevalonate to lovastatin-treated cells completely reversed the inhibition of PAF- and FMLP-stimulated Ca(2+)-mobilization. Immunoreactivity of ras-like proteins was decreased in membranes and increased in the cytosol of U937 cells by 1 day treatment with lovastatin. We conclude that isoprenylated proteins are involved in the regulation of receptor-stimulated Ca(2+)-entry of differentiated HL-60 and U937 cells.

Calcium↗
PubMed1994

Accumulation kinetics of propranolol in the rat: comparison of Michaelis-Menten-mediated clearance and clearance changes consistent with the "altered enzyme hypothesis".

(+)-Propranolol was infused at two rates into the pyloric vein (a portal vein tributary) of 15 male Sprague Dawley rats until apparent steady-state conditions were established (i.e., 8 hr at each rate). One group (n = 7) received the high dose (40 micrograms/min/kg) first, and in the other group (n = 8) the low dose (20 micrograms/kg/min) was used to initiate treatment. Free and total serum concentrations of propranolol were measured. When the low dose was given first, the apparent steady-state concentrations achieved during low- and high-rate infusion steps were 166 +/- 37 and 774 +/- 235 ng/mL, respectively. These data are consistent with a simple Michaelis-Menten kinetic model and the key parameters of such a model (Vmax and Km) were estimated. However, a crucial test of such a model (and one which should give insight regarding the relevance of an "altered enzyme hypothesis") is to reverse the order of infusion steps since, in a system controlled by Michaelis-Menten kinetics, the same steady-state concentrations should be achieved regardless of the order in which infusion steps are given. When the sequence of infusion rates was reversed, steady-state concentrations were 492 +/- 142 and 298 +/- 79 ng/mL for the high and low infusion rates, respectively. Clearly, a history of high-dose exposure reduces the intrinsic clearance of total drug (CLss) during a subsequent low-dose exposure (i.e., the apparent steady-state levels during the low-dose pyloric vein infusions were significantly different; P < 0.001). When these data were corrected for plasma protein binding, the same trends emerged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Antioxidants inhibit monocyte adhesion by suppressing nuclear factor-kappa B mobilization and induction of vascular cell adhesion molecule-1 in endothelial cells stimulated to generate radicals.

Cell adhesion to endothelial cells stimulated by tumor necrosis factor-alpha (TNF) is due to induction of surface receptors, such as vascular cell adhesion molecule-1 (VCAM-1). The antioxidant pyrrolidine dithiocarbamate (PDTC) specifically inhibits activation of nuclear factor-kappa B (NF-kappa B). Since kappa B motifs are present in VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) promoters, we used PDTC to study the regulatory mechanisms of VCAM-1 and ICAM-1 induction and subsequent monocyte adhesion in TNF-treated human umbilical vein endothelial cells (HUVECs). PDTC or N-acetylcysteine dose dependently reduced TNF-induced VCAM-1 but not ICAM-1 surface protein (also in human umbilical arterial endothelial cells) and mRNA expression (by 70% at 100 mumol/L PDTC) in HUVECs as assessed by flow cytometry and polymerase chain reaction. Gel-shift analysis in HUVECs demonstrated that PDTC prevented NF-kappa B mobilization by TNF, suggesting that only VCAM-1 induction was controlled by NF-kappa B. Since HUVECs released superoxide anions in response to TNF, and H2O2 induces VCAM-1, PDTC may act as a radical scavenger. Although ICAM-1 induction was unaffected, inhibitors of NADPH oxidase (apocynin) or cytochrome P-450 (SKF525a) suppressed VCAM-1 induction by TNF, revealing that several radical-generating systems are involved in its regulation. PDTC, apocynin, or SKF525a decreased adhesion of monocytic U937 cells to TNF-treated HUVECs (by 75% at 100 mumol/L PDTC). Inhibition by anti-VCAM-1 monoclonal antibody 1G11 indicated that U937 adhesion was VCAM-1 dependent and suppression by antioxidants was due to reduced VCAM-1 induction.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcysteine↗
PubMed1994

Preoperative localization of parathyroid tissue with technetium-99m sestamibi 123I subtraction scanning.

To evaluate the utility of technetium-99m (Tc-99m) sestamibi for visualization of functioning parathyroid tissue, 14 subjects underwent Tc-99m sestamibi 123I subtraction scanning as part of the preoperative evaluation for hyperparathyroidism. Informative scans were obtained in 13 subjects, including 7 patients with recurrent or persistent hyperparathyroidism, and correctly identified the location of the hyperfunctioning parathyroid tissue found at surgery. In all informative patients, hyperparathyroidism was due to adenomatous disease or hyperplasia secondary to renal failure. Successful scans were obtained with glands as small as 220 mg. In the lone patient in whom Tc-99m sestamibi scanning failed to localize hyperfunctioning parathyroid tissue, surgery revealed a 1700-mg hyperplastic parathyroid neoplasm in the neck. In no case did a Tc-99m sestamibi scan suggest parathyroid tissue where there was none. In 1 case, a patient presented with persistent hyperparathyroidism after 1 neck and a second combined neck and mediastinal exploration. Tc-99m sestamibi imaging revealed uptake in the periaortic region, and a 570-mg adenoma was found in the aortopulmonary window. Using only initial studies, prospective evaluation provided a sensitivity of 78.5% and a positive predictive value of 100%. After repeat studies in 5 patients, 2 of 3 patients with initially negative results and technically deficient scans became positive on restudy. Inclusion of these studies increased sensitivity to 93%. Tc-99m sestamibi 123I subtraction scanning appears to be a reliable noninvasive method for preoperative localization of hyperfunctioning parathyroid tissue.

Adult↗
PubMed1994

New cell biological applications of the laser microbeam technique: the microdissection and skinning of muscle fibers and the perforation and fusion of sarcolemma vesicles.

In a novel approach, the laser microbeam technique was used to selectively perforate the sarcolemma of skeletal muscle fibers, to prepare fragments of myofibrillar bundles of very small dimensions, and to induce fusion of sarcolemma vesicles. Using a highly focused UV laser microbeam with an effective beam diameter of down to 0.5 micron, very small (< 3 microns) myofibrillar fragments with an intact sarcomere striation pattern were obtained. When small amounts of Ca2+ were released in the vicinity of such a fragment by laser-photolysis of the photolabile compound Ca(2+)-nitr-7 the bundle shortened due to the development of calcium-activated force. We also show that very small selected areas from myopathic single muscle cells can be dissected with a precision unmatched by other current techniques. The microbeam was also used to remove very small patches of the sarcolemma of murine skeletal muscle fibers so giving diffusional access to the myoplasmic interior and thus resulting in a "skinning" of the fiber. To ensure that such laser-skinned fiber segments were physiologically intact we determined the Ca(2+)-activated force and caffeine-induced Ca(2+)-release from the sarcoplasmic reticulum. The fibers showed normal characteristics for force production, Ca(2+)-release and uptake by the sarcoplasmic reticulum. To test the effects of the laser microbeam on the muscle membrane directly, we prepared sarcolemma vesicles of skeletal muscle fibers. The vesicles could be selectively perforated with single laser pulses to allow entry of fluorescein isothiocyanate (FITC)-dextran as a fluorescent marker. Adjacent vesicles were caused to fuse by a few pulses at low intensity of the laser microbeam.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The Microspheres based Detoxification System (MDS). A new extracorporeal blood purification technology based on recirculated microspherical adsorbent particles.

Plasma sorption processes have so far been performed with filters and appropriate adsorption columns. In this paper, we introduce a newly developed plasma sorption system, which is based on the high adsorption capacity of microspheres in a recirculation system. The technology has been applied successfully in vitro to eliminate endotoxins, low density lipoproteins (LDL) and barbiturates from human plasma.

Animals↗