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Biomedical subjects

U Renner

Publications and source records attributed to U Renner.

14 recordsLinked to original sources
PubMed1995

Expression and localization of endothelin-1 and endothelin receptors in human meningiomas. Evidence for a role in tumoral growth.

In addition to its well-known homoeostatic actions in the cardiovascular system, ET-1 has been shown to constitute a potent growth regulatory peptide in various tissues. We have studied the expression of ET-1 and its receptors (ET-Ar and ET-Br) in human meningiomas (n = 35) as well as their involvement in cellular growth. By PCR of reverse-transcribed RNA we detected ET-1 mRNA in 91% (32 of 35), ET-Ar mRNA in 82% (29 of 35), and ET-Br mRNA in 42% (15 of 35) of human meningiomas examined. The localization of ET-1 mRNA, ET-Ar mRNA, and ET-1 peptide in tumoral cells was observed by in situ hybridization and immunohistochemistry, whereas ET-Br mRNA was expressed at low level only in cells belonging to blood vessels. In addition, we found that ET-1 stimulated [3H] thymidine incorporation in primary cell cultures of 20 meningiomas and that this effect could be blocked by BQ-123, a specific antagonist for ET-Ar. In contrast, RES-701-3, an antagonist of ET-Br, did not block the proliferative effect of ET-1. In conclusion, our data provide evidence that ET-1 constitutes an important growth factor for meningiomas acting via ET-Ar. We can hypothesize that ET-1, acting in concert with other growth factors and cytokines, is involved in the meningioma tumorigenesis.

Adult↗
PubMed1995

Involvement of interleukin-1 and interleukin-1 receptor antagonist in rat pituitary cell growth regulation.

Interleukin-1 (IL-1), one of the mediators of the interaction between the immune and the neuroendocrine system, is well known to modulate anterior pituitary hormone secretion. As IL-1 influences growth of various cell types, we investigated whether IL-1 is also a growth factor of pituitary cells. We demonstrate that IL-1 dose and time dependently inhibits the growth of normal rat pituitary cells under serum-free conditions. The inhibitory potencies of IL-1 alpha (ED50, 8 pg/ml) and IL-1 beta (ED50, 6 pg/ml) were nearly identical. In the presence of low amounts of serum, both IL-1 alpha (ED50, 130 pg/ml) and IL-1 beta (ED50, 90 pg/ml) were less effective in inhibiting growth. The IL-1-induced growth inhibition was IL-1 receptor mediated, because both IL-1 alpha- and IL-1 beta-mediated growth suppression could be completely reversed by the IL-1 receptor antagonist, the physiological counterpart of IL-1. In the mammosomatotroph GH3 rat pituitary tumor cell line, IL-1 failed to influence growth, indicating that either IL-1 receptors are missing or the IL-1 signaling pathway is uncoupled from the growth regulation. In contrast to growth, in our rat pituitary monolayer cell culture system, IL-1 did not affect ACTH, GH, or PRL secretion as described previously. This discrepancy suggests the involvement of different mechanisms in the IL-1-induced mediation of growth and hormone secretion.

Adrenocorticotropic Hormone↗
PubMed1995

Biotransformation of CI-937 in primary cultures of rat hepatocytes. Formation of glutathione conjugates.

The anticancer drug 7,10-dihydroxy-2-[2-[(2-hydroxyethyl)amino]- ethyl]-5-[[2-(methylamino)ethyl]amino]anthra[1,9-c,d]pyrazole- 6(2H)-one dihydrochloride (CI-937) is 1 of 3 anthrapyrazole derivatives chosen for phase I and phase II clinical trials. Although the chemical structure of CI-937 signals a contribution of redox reactions in the pharmacology of the drug, a study concerning the biotransformation of CI-937 is still missing. Incubations of primary cultures of rat hepatocytes with CI-937 result in the formation of three glutathione conjugates and a glucuronic acid conjugate. The structures of the glutathione conjugates have been established by reference synthesis with activated horseradish peroxidase and HPLC-MS-MS and two-dimensional NMR measurements. The glucuronic acid derivative of CI-937 has been identified by MS. The formation of the glutathione conjugates in cells establishes the ability of the drug to form covalent bonding to intracellular nucleophilic targets. The conjugation with glutathione has been rationalized by oxidative activation of CI-937, yielding an electrophilic intermediate that finally reacts with glutathione.

Animals↗
PubMed1992

Interleukin-2 and interleukin-2 receptor expression in human corticotrophic adenoma and murine pituitary cell cultures.

The production of IL-1 and IL-6 by pituitary cells has recently been demonstrated. In this study we investigated the expression of IL-2 and its receptor (IL-2R) by pituitary cells of different species. In Northern blots, a single hybridizing band of 1 kb, identical to that in normal stimulated lymphocytes, was obtained with specific IL-2 probes. In the mouse AT-20 pituitary tumor cell line, IL-2 mRNA expression was detected after stimulation with corticotropin-releasing hormone or phorbol myristate acetate. In human corticotrophic adenoma cells, basal IL-2 mRNA expression as well as IL-2 secretion were further stimulated by phorbol myristate acetate. Both adenoma and AtT-20 cells showed detectable amounts of IL-2R mRNA and by immunofluorescence, IL-2R membrane expression. In addition, dual immunofluorescence studies in rat anterior pituitary cells demonstrated colocalization of IL-2R with ACTH-positive cells and other cell types expressing the receptor. In addition to the action of lymphocyte-produced IL-2, this cytokine may have a paracrine or autocrine regulatory role within the pituitary. It remains to be established whether IL-2 production occurs in the normal pituitary or is intrinsic to the process of tumor development of these cells. IL-2 may be involved in the growth control of pituitary cells.

Adenoma↗
PubMed1990

[Accuracy of various Doppler technics in recording blood flow velocity. Studies in vitro].

Conventional and color-coded Doppler techniques were studied as to their accuracy in displaying flow and velocity using an in vitro model and a Laser-Doppler-anemometer. Furthermore, the estimation of pressure gradients as determined by Doppler ultrasound was compared to measurements by manometers under a variety of hemodynamic conditions. Pulsed and continuous wave Doppler had good reproducibility. There was an excellent correlation for measurements of flow velocity as determined by Doppler ultrasound and by Laser-Doppler anemometer (r = 0.98, SEE = 3 cm/s). The well-known underestimation of flow velocity due to an increasing angle of incidence (greater than 25 degrees) was confirmed in vitro. However this error was smaller than the actual overestimation resulting from angle correction for the apparent cosine. Doppler gradients correlated strongly with manometer gradients for orifice areas 12-80 mm2 and flow volumes 0.9-12.8 l/min (r = 0.98, SEE = 7 mm Hg) using continuous as well as pulsatile flow. Some overestimation of the Doppler gradient occurred with increasing flow rates (r = 0.66). Color-Doppler has poor spatial resolution. Display of velocities was therefore assessed using a qualitative score (0-5), the variability of which was 13 +/- 30% of the initial value. Display of faintest quality (score 1) was useless for clinical assessment in color-Doppler technique, but allowed quantitative measurement of velocity in conventional Doppler. Reduction of flow velocities limited display in color-Doppler (5-20 cm/s) but not in pulsed-Doppler technique. Thus, conventional Doppler has better sensitivity and accuracy of displaying flow when compared to color-Doppler, particularly in conditions of poor imaging. As reproducibility and accuracy of velocity determination are excellent, this technique should be used in all diagnostic procedures involving ultrasound. The Doppler gradient as derived from the modified Bernoulli equation provides accurate results in vitro which may also be concluded for use in the clinical situation.

Blood Flow Velocity↗
PubMed1989

[Contrast-color Doppler echocardiography. Improved right heart diagnosis following intravenous injection of Echovist].

Flow patterns in the right heart are often difficult to visualize by color-coded Doppler flow imaging. The echogenicity of blood was increased in 48 patients by intravenous injection of 10 ml echovist (200 mg/ml), a saccharide solution with defined size and concentration of microbubbles. Its effect on improving color-coding was compared with the effect of agitated gelifundol (10 ml) in 21 patients with tricuspid valve regurgitation. The non-controlled size and concentration of microbubbles resulted in weaker or uncontrollably exaggerated color-coding in half of the patients. In eight normals biphasic atrial flow was visible only after injection of echovist. In 25 patients with tricuspid regurgitation the blue coded area of reflux was 25 +/- 21% of the atrial area from the parasternal approach and 10 +/- 9% from the apical approach without correlation of these results. After echovist the area of reflux was 57 +/- 31% (p less than 0.001) in the parasternal and 53 +/- 26% (p less than 0.001) in the apical approach (r = 0.83). This was paralleled by an increase of the severity of tricuspid regurgitation as defined by the length or area of reflux (p less than 0.01-0.001). The qualitative diagnosis was safely established in the five patients with VSD in the control color Doppler flow imaging, but only in three out of 10 patients with ASD, and in nine of 10 after injection of echovist. The intravenous injection of echovist, when using color-coded Doppler flow imaging for evaluation of right heart disease, facilitates the qualitative diagnosis of ASD and also of tricuspid regurgitation, particularly in the apical approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Asymptomatic course of severe tricuspid valve insufficiency with ateroseptal infarct, coronary fistula and ventricular septum defect as a sequela of blunt thoracic trauma].

Traumatic tricuspid valve insufficiency is a rare in vivo finding, especially in combination with other traumatic cardiac injuries like ventricular septal defect, myocardial infarction, and traumatic coronary fistula. Two-dimensional and, more recently, colorcoded Doppler echocardiography have gained importance for the diagnosis of tricuspid insufficiency. Patients with traumatic tricuspid insufficiency who survive the acute trauma, may remain asymptomatic for many years and even decades. If symptoms develop, tricuspid valve replacement appears feasible even after many years.

Adult↗
PubMed1988

[Peripheral pulmonary stenosis: initial manifestation of a malignant teratoma].

A case of acquired pulmonic stenosis is described. The only symptoms reported by the patient, a seemingly healthy woman, were minor chest discomfort and mild dyspnea upon exertion for the last six month. Cardiac catheterization revealed stenoses of both the right and left pulmonary arteries. Magnetic resonance imaging revealed a mediastinal tumor mass that almost totally compressed the right main pulmonary artery and also encroached upon the left pulmonary artery. Histologically the tumor was a malignant teratoma. The subsequent course of treatment was complicated by cardiac tamponade. With regression of the tumor during therapy the signs of pulmonic stenosis disappeared. In cases with acquired pulmonic stenosis an underlying mediastinal tumor has to be considered.

Adult↗
PubMed1987

[Slow increase in the size of the left atrium with atrial fibrillation--a congenital pericardial defect or aneurysm of the left atrium?].

Gradual left atrial enlargement and development of atrial fibrillation--congenital pericardial defect or left atrial aneurysm? Left atrial aneurysms are rare. Whether or not a pericardial defect is associated can be ascertained by a diagnostic left-sided pneumothorax with air entering the pericardial cavity, although a negative finding does not necessarily rule out the presence of a defect. Cardiac surgery (aneurysmectomy) is advisable if the patient develops significant symptoms or if there is a progressive increase in atrial size. A case is presented with progressively increasing left atrial aneurysm and the development of atrial fibrillation. Although a pericardial defect was postulated (from echocardiogram, MR, CT, angiogram) the pericardium was found to be intact at surgery.

Atrial Fibrillation↗
PubMed1984

Floating pulmonary embolus: unusual cause of recurrent syncope.

A 69-year old woman was admitted because of recurrent syncopal episodes. In hospital, she had repeated attacks of near fainting or syncope when she was turned into the left decubitus position. Continuous arterial pressure monitoring revealed that severe hypotension initiated these events. Secondarily, the heart rate dropped markedly. The symptoms quickly reversed when the patient was turned back into the supine or right decubitus position. Angiography revealed a large, riding and partly floating pulmonary embolus that obstructed the pulmonary circulation to a variable degree, apparently influenced by the patient's body position. During subsequent emergency surgery the angiographic findings were confirmed. It appears that the severe hypotensive episodes were caused by intermittent high degree obstruction of the pulmonary circulation by the floating pulmonary embolus, a mechanism that, to our knowledge, has not previously been described as a cause of recurrent syncope.

Aged↗
PubMed1967

[Conoflorin].

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Alkaloids↗