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Biomedical subjects

A Uhrig

Publications and source records attributed to A Uhrig.

17 recordsLinked to original sources
PubMed2003

The role of monocyte chemoattractant protein-1 in orthotopic liver transplantation.

Hepatic ischemia reperfusion injury as well as acute graft rejection (RE) after orthotopic liver transplantation (OLT) are associated with leukocyte invasion of the graft. Local synthesis of chemokines is a key reaction in the recruitment and activation of inflammatory leukocytes and consequent liver damage. In this paper we describe the role of monocyte chemoattractant protein (MCP)-1 (CCL2) in human OLT. We investigated the serum CC-chemokine levels for MCP-1 by specific ELISAs after OLT in 105 human liver allografts between September 1997 and January 2001. One hour after reperfusion we saw a significant (t test) increase of MCP-1 in peripheral blood (92.5 +/- 85.8 pg/mL to 774.2 +/- 319.6 pg/mL, 8.3-fold, P <.0001), hepatic venous blood (92.5 +/- 85.8 pg/mL to 866.7 +/- 376.1 pg/mL, 9.3-fold, P <.0001), and portal venous blood (92.5 +/- 85.8 pg/mL to 792.9 +/- 408.0 pg/mL, 8.5-fold, P < 0.0001) during hepatic ischemia reperfusion injury. An analysis of the correlation (Spearman's test, rs) between the expression of MCP-1 and the AST (rs 0.555, P <.025) and ALT (rs 0.852, P <.0001) showed a significant linear correlation. During RE a significant (t test) increase of MCP-1 (125.5 +/- 95.6 pg/mL to 188.5 +/- 124.6 pg/mL, 3.86-fold, P <.0001) was demonstrated. The successful treatment of the RE led again to a decline to lower base levels. Hepatic ischemia reperfusion syndrome as well as RE after OLT are characterized by typical patterns of CCL-2 overexpression. This finding proposes a new noninvasive, early diagnostic test after OLT.

Acute Disease↗
PubMed1999

Endotoxin down-regulates T cell activation by antigen-presenting liver sinusoidal endothelial cells.

Endotoxin is physiologically present in portal venous blood at concentrations of 100 pg/ml to 1 ng/ml. Clearance of endotoxin from portal blood occurs through sinusoidal lining cells, i.e., Kupffer cells, and liver sinusoidal endothelial cells (LSEC). We have recently shown that LSEC are fully efficient APCs. Here, we studied the influence of endotoxin on the accessory function of LSEC. Incubation of Ag-presenting LSEC with physiological concentrations of endotoxin lead to >/=80% reduction of the accessory function, measured by release of IFN-gamma from CD4+ T cells. In contrast, conventional APC populations rather showed an increase of the accessory function after endotoxin treatment. Inhibition of the accessory function in LSEC by endotoxin was not due to lack of soluble costimulatory signals, because neither supplemental IL-1beta, IL-2, IFN-gamma, or IL-12 could rescue the accessory function. Ag uptake was not influenced by endotoxin in LSEC. However, we found that endotoxin led to alkalinization of the endosomal/lysomal compartment specifically in LSEC but not in bone marrow macrophages, which indicated that Ag processing, i.e., proteolytic cleavage of protein Ags into peptide fragments, was affected by endotoxin. Furthermore, endotoxin treatment down-regulated surface expression of constitutively expressed MHC class II, CD80, and CD86. In conclusion, it is conceivable that endotoxin does not alter the clearance function of LSEC to remove gut-derived Ags from portal blood but specifically affects Ag processing and expression of the accessory molecules in these cells. Consequently, Ag-specific immune responses by CD4+ T cells are efficiently down-regulated in the hepatic microenvironment.

Animals↗
PubMed1998

Interleukin-10 expression is autoregulated at the transcriptional level in human and murine Kupffer cells.

Interleukin 10 (IL-10) is known to downregulate immune responses. The regulation of IL-10 gene expression therefore determines the outcome of local immune reactions. We investigated time course and downregulation of IL-10 production in primary Kupffer's cells (KC), which are known to secrete IL-10 in response to endotoxin challenge. Human and murine KC were isolated by centrifugal elutriation and investigated for IL-10 gene expression by a two-step amplification procedure (reverse transcriptase-polymerase chain reaction [PCR] followed by T7-polymerase chain reaction). We show that IL-10 messenger ribonucleic acid (mRNA) showed a >450 fold increase in KC 2 hours after endotoxin challenge. IL-10 protein release from KC strictly depended on de novo protein synthesis. Endotoxin mediated increase in IL-10 gene expression was downregulated by exogenous (>350-fold reduction of IL-10 mRNA level), as well as endogenous IL-10 protein, showing a negative autoregulatory feedback loop. IL-10 receptor expression was found to be constitutive and functional in KC. Early expression of IL-10 in KC may be of functional relevance to the outcome of immune and inflammatory reactions in the liver sinusoid. The negative autoregulation of IL-10 expression may represent a mechanism to regain a state of functional responsiveness in the microenvironment towards new proinflammatory stimuli. In conclusion, autoregulatory downregulation of IL-10 expression in KC may account for important regulatory steps of local immune response in the liver sinusoid.

Animals↗
PubMed1998

IL-10 down-regulates T cell activation by antigen-presenting liver sinusoidal endothelial cells through decreased antigen uptake via the mannose receptor and lowered surface expression of accessory molecules.

Our study demonstrates that antigen-presenting liver sinusoidal endothelial cells (LSEC) induce production of interferon-gamma (IFN-gamma) from cloned Th1 CD4+ T cells. We show that LSEC used the mannose receptor for antigen uptake, which further strengthened the role of LSEC as antigen-presenting cell (APC) population in the liver. The ability of LSEC to activate cloned CD4+ T cells antigen-specifically was down-regulated by exogenous prostaglandin E2 (PGE2) and by IL-10. We identify two separate mechanisms by which IL-10 down-regulated T cell activation through LSEC. IL-10 decreased the constitutive surface expression of MHC class II as well as of the accessory molecules CD80 and CD86 on LSEC. Furthermore, IL-10 diminished mannose receptor activity in LSEC. Decreased antigen uptake via the mannose receptor and decreased expression of accessory molecules may explain the down-regulation of T cell activation through IL-10. Importantly, the expression of low numbers of antigen on MHC II in the absence of accessory signals on LSEC may lead to induction of anergy in T cells. Because PGE2 and IL-10 are released from LSEC or Kupffer cells (KC) in response to those concentrations of endotoxin found physiologically in portal venous blood, it is possible that the continuous presence of these mediators and their negative effect on the local APC may explain the inability of the liver to induce T cell activation and to clear chronic infections. Our results support the notion that antigen presentation by LSEC in the hepatic microenvironment contributes to the observed inability to mount an effective cell-mediated immune response in the liver.

Animals↗
PubMed1996

Antigen-presenting function and B7 expression of murine sinusoidal endothelial cells and Kupffer cells.

BACKGROUND & AIMS: Inflammatory liver disease as well as rejection of liver allografts are thought to be mediated by resident antigen-presenting cells in the liver. At the same time, in vivo antigen presentation in the liver appears to be a more tolerogenic than systemic antigen challenge. The aim of this study was to show and characterize the antigen-presenting capability of sinusoidal endothelial cells and Kupffer cells. METHODS: Purified murine sinusoidal endothelial cells and Kupffer cells were studied for their ability to serve as accessory cells and antigen-presenting cells by proliferation assays. They were also studied for their expression of interleukin 1 and the B7 costimulatory molecules by Northern blotting, polymerase chain reaction, and flow cytometry. RESULTS: Both cell types expressed interleukin 1 messenger RNA and could serve equally well as accessory and antigen-presenting cells. B7-2 messenger RNA and surface expression on sinusoidal endothelial cells and on Kupffer cells was shown. Antibodies to the B7 molecules inhibited antigen presentation. Addition of interleukin 10 as a regulatory cytokine secreted by Kupffer cells was suppressive. CONCLUSIONS: Sinusoidal endothelial cells carry functional B7-2 molecules and can serve as effective antigen-presenting cells. However, antigen presentation by sinusoidal endothelial cells may be locally down-regulated by interleukin 10.

Animals↗
PubMed1995

Human Kupffer cells secrete IL-10 in response to lipopolysaccharide (LPS) challenge.

BACKGROUND/AIMS: Kupffer cells are involved in local immunoregulation in the liver by secretion of cytokines and direct cellular contact. They are able to influence the function of other liver cells, i.e. sinusoidal endothelial cells, Ito cells and hepatocytes. The three known major functions of Kupffer cells are clearance of endotoxin from the portal circulation, release of soluble mediators and presentation of antigen. METHODS: Human Kupffer cells were isolated by collagenase perfusion followed by centrifugal elutriation and analyzed for cytokine secretion after 3 days in culture. RESULTS: We found that freshly isolated human Kupffer cells secreted the anti-inflammatory cytokine interleukin-10 in response to stimulation with lipopolysaccharide. The release of interleukin-10 was maximal 12-24 h after lipopolysaccharide challenge. Furthermore, we could show that exogenous interleukin-10 downregulated the release of the proinflammatory cytokines interleukin-6 and tumor necrosis factor alpha by Kupffer cells after lipopolysaccharide stimulation. The release of interleukin-6 was maximal 24 h after stimulation and interleukin-10 inhibited interleukin-6 release after 6 h. Tumor necrosis factor alpha showed maximal secretion 6 h after stimulation and exogenous interleukin-10 also downregulated the tumor necrosis factor alpha release after 6 h. CONCLUSIONS: Kupffer cells are exposed physiologically to lipopolysaccharide present in portal venous blood. Given the known anti-inflammatory effect of interleukin-10, our findings of secretion of interleukin-10 by Kupffer cells in response to lipopolysaccharide and suppression of interleukin-6 and tumor necrosis factor alpha release by Kupffer cells in vitro through exogenous interleukin-10 suggest an important role for interleukin-10 in the regulation of the local immune response in the liver sinusoid.

Cytokines↗
PubMed1994

[Left ventricular filling behavior in stress-induced myocardial ischemia--correlation between Doppler echocardiography determined transmitral flow profile and pulmonary capillary pressure].

The way Doppler-derived transmitral filling patterns are changed because of myocardial ischemia is controversial. Furthermore, the influence of the filling pressure has not been investigated sufficiently. To evaluate the relationship between transmitral flow profile and pulmonary capillary wedge pressure (PC), 35 patients with exercise-induced myocardial ischemia were examined. Both Doppler-derived transmitral filling patterns and PC were determined simultaneously at rest and during three stages of supine bicycle exercise. Patients were subdivided into two groups according to the hemodynamic response (group 1 = PC < 20 mm Hg; n = 10, and group 2 = PC > or = 20 mm Hg; n = 25). The correlation between PC and transmitral filling patterns was low at rest for all patients, but improved at maximal workload, particularly for the atrial contribution (r = -0.79), as well as the ratio of maximal and integrated early to late diastolic flow velocities (rE/A = 0.74; rEi/Ai = 0.72). Both groups revealed different flow profiles in regard to the hemodynamic response. While group 1 showed an E/A-ratio < 1, an E/A-ratio > 1 was registered in group 2 (0.9 m/s versus 1.61 m/s; p < 0.001). Exercise-induced myocardial ischemia lead to different Doppler-derived transmitral flow patterns with regard to the filling pressure. The relationship to the pulmonary capillary wedge pressure is so close that an E/A-ratio > 1 is a reliable parameter to predict a filling pressure > 20 mm Hg.

Adult↗
PubMed1993

[Late cardiac toxicity in Hodgkin's disease. A study with pulsed Doppler echocardiography].

49 patients (22 women, 27 men, mean age 43.7 [21-65] years) with Hodgkin's disease were examined by Doppler echocardiography a median of 5.37 (2-10) years after the end of chemotherapy (given according to the COPP/ABVD scheme, with or without mediastinal irradiation) for possible chronic changes in myocardium, pericardium or cardiac valves, as well as for any haemodynamic sequelae. Maximal and integrated early (E, Ei) and late (A, Ai) diastolic flow velocities and their ratio (E/A, Ei/Ai) were measured by pulsed Doppler over the mitral and tricuspid valves. Although on two-dimensional echo 21 patients (42.9%) were found to have valvar thickening, 19 (38.8%) pericardial thickening and 9 (18.4%) a reduced fibre shortening fraction, the Doppler indices were statistically not significantly different from those in 25 controls with normal hearts. These echocardiographic data of functional and morphological parameters indicate that there was no effect on various measurements of diastolic function after chemotherapy with or without mediastinal radiation. In successfully treated patients with Hodgkin's disease the described changes are of minor significance.

Adult↗
PubMed1993

Acute alterations of pre- and afterload: are Doppler-derived diastolic filling patterns able to differentiate the loading condition?

The net effects of acute changes in pre- and afterload on left ventricular filling, were examined by altering loading conditions in normal subjects. The specific purpose of this study was to investigate whether Doppler-derived transmitral flow patterns are able to differentiate the type of loading conditions. In 24 normal subjects (13 females, 11 males, mean age 44.1 +/- 11.5 years), the following Doppler variables were determined at baseline, after rapid volume infusion (preload increase), after nitroglycerin administration (preload decrease), during isometric exercise (afterload increase), and after application of a converting enzyme inhibitor (afterload decrease): the peak and integrated early (E, Ei) and late (A, Ai) diastolic flow velocities, their ratios (E/A, Ei/Ai), the percentage of atrial contribution (ACON), and the acceleration and deceleration times (Ac, Dc) of early filling. Reduced preload and increased afterload led to similar filling patterns characterized by a significant E and Ei decrease (p < 0.05, compared to baseline) accompanied by an A and Ai increase with a resultant reduction of E/A and Ei/Ai. Both changes increased the atrial contribution to filling and reduced Ac and Dc. Increased preload only significantly increased E and Ei, while reduced afterload did not induce any significant changes. Different loading conditions alter Doppler-derived diastolic filling patterns. However, the transmitral flow profile is not specific enough to distinguish the manner in which loading conditions have been altered.

Adult↗
PubMed1993

Evaluation of late cardiotoxicity with pulsed Doppler echocardiography in patients treated for Hodgkin's disease.

The impact of valvular, myocardial and pericardial abnormalities on cardiac haemodynamics in patients treated for Hodgkin's disease with COPP/ABVD with and without mediastinal irradiation was determined in 49 patients 2-10 years after induction therapy. Diagnostic procedures to evaluate cardiac function consisted of history, physical examination, exercise bicycle stress test, M-mode two-dimensional and pulsed Doppler echocardiography. No patient reported symptoms related to cardiomyopathy, and only one of the 49 had evidence of coronary heart disease. Pericardial thickening was seen on echocardiograms in 19/49 patients (38.8%), valvular thickening in 21/49 (42.9%), and reduced fractional shortening in 9/49 (18.4%). The Doppler-derived mean E and A (+/- SD) of transmitral flow were 0.75 +/- 0.14 m/s and 0.56 +/- 0.09 m/s, respectively, in patients receiving chemotherapy and 0.81 +/- 0.19 m/s and 0.63 +/- 0.20 m/s in those with additional mediastinal irradiation. There was no statistically significant difference between mean E and A in transmitral flow in patients treated for Hodgkin's disease and control subjects. Furthermore, the transtricuspid and hepatic vein flow velocities did not differ significantly. Although the present study demonstrates high frequencies of pericardial and valvular thickening in patients treated for Hodgkin's disease with the COPP/ABVD regimen with or without mediastinal irradiation, it showed no impact on cardiac flow velocities. The abnormalities might thus be of minor clinical relevance in these patients.

Adult↗
PubMed1993

Does cardiac function modify left heart opacification with transpulmonary echo contrast agents?

Dependence of left heart opacification on ventricular function was evaluated for the new transpulmonary echo enhancing agent (SH U 508-A). The contrast agent was injected intravenously in 5 patients with normal cardiac function (ejection fraction [EF] greater than 60% and echocardiographic left ventricular end-diastolic diameter [LVED] less than 56 mm) and in five patients with pathological ventricular function (EF less than 40%, LVED greater than 65 mm). A concentration of 400 mg/mL with dosages of 5, 9, and 16 mL was used in all patients. The visually assessed signal enhancement as well as the videodensitometrically determined peak intensity and duration of signal enhancement did not differ significantly between the two patient groups, while the transit times were markedly prolonged in patients with impaired ventricular function. No significant alteration was found for systemic blood pressure and heart rate. Side effects were transitory and dose related. The noninvasive nature of the procedure and the absence of hemodynamic effects make repeated studies of left ventricular performance with SH U 508-A in patients with varied hemodynamic status possible.

Aged↗
PubMed1993

[Pulmonary edema as a complication during pericardial puncture in "mixed connective tissue disease"].

A 22-year-old female patient with an 8-year history of mixed connective tissue disease (systemic sclerosis overlapping with systemic lupus erythematosus) presented with marked respiratory distress, sinus tachycardia (135 bpm), and pulsus paradoxus. The chest x-ray showed an enlargement of the cardiac silhouette, which was due to a 3-cm-wide, circular pericardial effusion, as demonstrated by two-dimensional echocardiography. Pericardiocentesis performed to decompress cardiac tamponade did not lead to clinical improvement. The increase in dyspnea was caused by a rise in pulmonary wedge pressure from 21 to 40 mm Hg following an acute increase of mitral valve regurgitation. In the presence of global hypokinesia of the left ventricle, cardiac output decreased from 3.25 to 2.63 l/min. Intensive care including hemodialysis and plasmapheresis as well as high-dose application of cyclophosphamide and steroids led to a stabilization of the hemodynamic situation over a period of days. The case report presented here supports the general recommendation to perform pericardiocentesis in a stepwise manner under hemodynamic monitoring. This holds true primarily for patients with mitral valve regurgitation and/or cardiac involvement in connection with an underlying disease.

Adult↗
PubMed1992

[Doppler echocardiography measurement of diastolic filling parameters in acute changes of pre- and afterload in healthy probands].

For a more precise understanding of the net effects of acute alterations of pre- and afterload on left-ventricular filling, loading conditions were altered in normal subjects. The specific purpose of this study was to investigate if Dopplerechocardiographically derived transmitral flow patterns are able to differentiate the manner of loading condition. In 24 normal subjects (13 female, 11 male, mean age 44.1 +/- 11.5 years) the following Doppler variables were analyzed at baseline, after rapid infusion of volume (preload increase), nitroglycerine (preload decrease), isometric exercise (afterload increase) and converting enzyme inhibitor (afterload decrease): peak and integrated early (E, Ei) and late (A, Ai) diastolic flow velocities, their ratios (E/A, Ei/Ai), the percentage of atrial contribution (ACON) and the times of acceleration (Az) and deceleration (Dz) of early filling. Preload reduction as well as afterload increase led to a similar filling pattern with a significant decrease (p < 0.05 from baseline) of E and Ei, increase of A and Ai, and, consequently, a reduction of E/A and Ei/Ai. The atrial contribution to filling increased during both alterations; Az and Dz were reduced. Following the increase of preload, only the increase of E and Ei was statistically significant, while afterload reduction showed no significant differences. Different loading conditions alter Doppler-derived diastolic filling patterns. But the transmitral flow profile is not specific enough to differentiate in which manner loading conditions have been altered.

Adult↗
PubMedDate not supplied

Hemodynamic response to exercise-induced myocardial ischemia detected by transmitral filling patterns derived from Doppler echocardiography.

There is still controversy as to the manner in which Doppler-derived transmitral filling patterns change because of myocardial ischemia. To evaluate the effects of exercise-induced ischemia on Doppler-derived filling patterns, 28 patients were examined at rest and during three stages of supine bicycle exercise (0.5, 1.0, and 1.5 W/kg). The peak early (E) and integrated early (Ei) and peak late (A) and integrated late (Ai) diastolic flow velocities, as well as their ratios (E/A, Ei/Ai), were compared between patients with exercise-induced ischemia but no wall-motion abnormalities at rest (ischemia group, n = 13) and those with akinetic scars from previous infarction but no exercise ischemia (scar group, n = 15). Normal subjects with no evidence of heart disease served as a control group (n = 11). At maximal workload the ischemia group showed a significantly lower peak flow velocity at atrial contraction than the control and scar group (0.74 +/- 0.18 vs 1.08 +/- 0.25 and 0.89 +/- 0.19 m/sec, respectively; p < 0.05) and also a significantly lower flow velocity integral at atrial contraction (8.24 +/- 2.2 vs 12.81 +/- 4.8 and 11.32 +/- 3.6 cm, respectively; p < 0.05). Therefore, the atrial contribution to filling was diminished during ischemia (36.2% +/- 9.2% vs 47.3% +/- 6.4% and 48.4% +/- 13.8%, respectively; p < 0.05). By maintaining the early filling rate during ischemia, the reduced atrial contribution resulted in a significantly higher E/A ratio (1.48 +/- 0.31 vs 1.05 +/- 0.15 and 1.16 +/- 0.44, respectively) and Ei/Ai ratio (2.0 +/- 1.06 vs 1.09 +/- 0.26 and 1.24 +/- 0.79, respectively). The assessment of Doppler-derived transmitral filling during exercise-induced ischemia shows mainly early diastolic filling, which is in contrast to the profile of impaired relaxation usually associated with ischemia. Evidence of exercise-induced ischemia leading to greater increases in left atrial pressure suggests that transmitral filling patterns are more closely related to hemodynamic status than to diastolic function.

Aged↗