1,721,151 research outputs found
LHRH might act as a negative autocrine regulator of proliferation of human ovarian cancer
No full textObjective: More than 80% of human ovarian cancers express LHRH and its receptor. The proliferation of human ovarian cancer cell lines is reduced by both LHRH agonists and antagonists. This study was designed to further clarify the possible biological function of this LHRH system. Design: As LHRH agonists and antagonists uniformly reduce proliferation of human ovarian cancer in a dose-dependent way, the effect of low concentrations of authentic LHRH was studied, In addition, longer periods of treatment (up to 9 days) were analyzed, To assess the physiological role of LHRH produced by ovarian cancer cells it was neutralized by adequate concentrations of a specific LHRH antiserum. Methods: Human ovarian cancer cells EFO-21 and EFO-27, which express LHRH and its receptor, were incubated for 1-9 days with increasing concentrations (1 pmol/l to 10 mu mol/l) of authentic LHRH or with concentrations of LHRH antiserum capable of neutralizing at least 1 nmol/l LHRH. Proliferation was assessed by counting cells. Results and conclusions: Authentic LHRH reduced time- and dose-dependently proliferation (by maximally mean +/- S.E.M. 32.7 +/- 4.4%, Newman-Keuls, P < 0.001) of both ovarian cancer cell lines. At very low concentrations (1 pmol/l) a marginal reduction of proliferation or no effect was observed. A mitogenic effect of authentic LHRH was never detected. Treatment of ovarian cancer cell cultures with antiserum to LHRH significantly increased (up to mean +/- S.E.M. 121.0 +/- 2.8% of controls, Newman-Keuls P < 0.001) proliferation of EFO-21 and EFO-27 cells. These findings suggest that LHRH produced by human ovarian cancer cells might act as a negative autocrine regulator of proliferation
The possible role of estrogens and progestagens in the prevention of osteoporosis
No full textThe multifactorial disease of osteoporosis is one of the most frequent diseases, affecting about 5 - 6 Mio. postmenopausal women in Germany, today. In spite of the introduction of new technologies of fracture risk assessment and new pharmacological opportunities the incidence of fracture is still increasing. Therefore, early identification of women at high risk as well as early and individualised preventive measures are essential in the prevention of osteoporosis. Changes of dietary habits as well as lifestyle including an increase in physical activity are of up most importance. In addition to Calcium and Vitamin D supplementation, hormone replacement therapy (HRT) is accepted as the first line and cost effective pharmacological treatment for the prevention of osteoporosis. Numerous cross sectional, case-control and prospective studies showing the effect of HRT on bone reabsorption and bone mineral density (BMD) have been published. HRT reduces bone turnover which is followed by an increase of BMD. A number of case-control and cohort studies as well as a few recent prospective studies have been investigating the effect of HRT on osteoporosis related fracture. These studies confirm that HRT leads to a significant decrease of osteoporosis related fracture (Hip fracture by > 25 %). However, randomised, prospective studies are needed to underline the effect on osteoporosis related fracture. Although the effect of HRT on BMD is independent of both, the age at which treatment is started and the route of administration, a dose-response relation as well as a greater response in patients with a lower initial BMD has been reported. Since bone is lost rapidly when treatment is stopped, the duration of treatment is clinically important in evaluating the effect of HRT on BMD. Hereby, a duration of 10 years and more seems desirable. Since the ongoing controversial discussion on the duration dependent increase of the incidence of breast cancer and the discussion on secondary prevention of cardiovascular disease, any therapy decision must be individually evaluated. The following article gives a systematical review on the recent literature regarding the influence of HRT on BMD and osteoporosis related fracture
Bedeutung der Interaktionen zwischen Östrogen- und Wachstumsfaktor-Signalwegen für die Wirkung antitumoraler Substanzen in den Ovarialkarzinomzelllinien BG-1 und SKOV-3
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Untersuchungen über die wechselseitige Beeinflussung von Östrogenrezeptor- und Rezeptortyrosinkinase-Signalwegen anhand des Proliferationsverhaltens humaner endometrialer Adenokarzinomzellen
No full textEinflüsse von Östradiol und Progesteron auf die Phorbolester-stimulierte LH-Sekretion aus kultivierten Rattenhypophysenzellen
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