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Biomedical subjects

C Keck

Publications and source records attributed to C Keck.

At least 19 recordsLinked to original sources
PubMed2006

Cytochrome P2A13 and P1A1 gene polymorphisms are associated with the occurrence of uterine leiomyoma.

PROBLEM: To investigate the association between the occurrence of uterine leiomyoma and two SNPs of the CYP 2A13 and CYP 1A1 genes. METHOD OF STUDY: Prospective case control study with 132 women with clinically and surgically diagnosed uterine leiomyoma and 260 controls. Genotyping was performed by polymerase chain reaction (PCR) based amplification of CYP 2A13 and CYP 1A1 genes, and restriction fragment length polymorphism (RFLP) analysis. RESULTS: Comparing women with uterine leiomyoma and controls, we demonstrate statistical significant differences of allele frequency and genotype distribution for the CYP 1A1 polymorphism (P = 0.025 and P = 0.046, respectively). Furthermore, for the CYP 2A13 polymorphism we found a significant difference concerning allele frequency (P = 0.033). However, for the genotype distribution, only borderline significance was observed (P = 0.064). CONCLUSIONS: The CYP 2A13 and CYP 1A1 SNPs are associated with uterine leiomyoma in a Caucasian population and may contribute to the understanding of the pathogenic mechanisms of uterine leiomyoma.

Adult↗
PubMed2006

hCG-dependent regulation of angiogenic factors in human granulosa lutein cells.

As prerequisite for development and maintenance of many diseases angiogenesis is of particular interest in medicine. Pathologic angiogenesis takes place in chronic arthritis, collagen diseases, arteriosclerosis, retinopathy associated with diabetes, and particularly in cancers. However, angiogenesis as a physiological process regularly occurs in the ovary. After ovulation the corpus luteum is formed by rapid vascularization of initially avascular granulosa lutein cell tissue. This process is regulated by gonadotropic hormones. In order to gain further insights in the regulatory mechanisms of angiogenesis in the ovary, we investigated these mechanisms in cell culture of human granulosa lutein cells. In particular, we determined the expression and production of several angiogenic factors including tissue inhibitor of matrix metalloproteinases-1 (TIMP-1), Leptin, connective tissue growth factor (CTGF), meningioma-associated complimentary DNA (Mac25), basic fibroblast growth factor (bFGF), and Midkine. In addition, we showed that human chorionic gonadotropin (hCG) has distinct effects on their expression and production. hCG enhances the expression and production of TIMP-1, whereas it downregulates the expression of CTGF and Mac25. Furthermore it decreases the expression of Leptin. Our results provide evidence that hCG determines growth and development of the corpus luteum by mediating angiogenic pathways in human granulosa lutein cells. Hence we describe a further approach to understand the regulation of angiogenesis in the ovary.

Angiogenesis Inducing Agents↗
PubMed2006

Expression of Eph receptor tyrosine kinases and their ligands in human Granulosa lutein cells and human umbilical vein endothelial cells.

Corpus luteum development is regulated by gonadotropins and accompanied by extremely rapid vascularization of the avascular granulosa cell compartiment by endothelial cells (EC). The proliferation of Granulosa cells (GC) and EC is a complex interplay and takes place in a spatially and temporarily coordinated manner. The erythropoietin-producing hepatoma amplified sequence (Eph) receptors and their ligands-the ephrins- are a recently detected family of membrane located protein tyrosine kinases which play a crucial role in the growth and development of nerve and blood vessel network. We report about the mRNA expression pattern of Ephs and their ligands in human GC, in human EC, and in carcinoma cell lines OvCar-3 and Hela. The mRNA of EphA4, EphA7, ephrinA4, ephrinB1 and ephrinB2 was detected in GC and EC, while EphA2 was expressed only in GC. The expression of various Ephs and ephrins did not change in GC after stimulation with human chorion gonadotropin. Our study analyzes for the first time the expression of the complete human Eph/ephriny-system in GC and in EC. The remarkable similarity between these two cell types supports the theory of a functional relationship of EC and GC. In addition, it was shown that hCG is not a major determinant of Eph/ephrin regulation in GC.

Cell Separation↗
PubMed2005

Effects of luteinizing hormone and human chorionic gonadotropin on corpus luteum cells in a spheroid cell culture system.

The human corpus luteum (CL) is a highly vascularized, temporarily active endocrine gland and consists mainly of granulosa cells (GCs), theca cells (TCs), and endothelial cells (ECs). Its cyclic growth and development takes place under the influence of gonadotropic hormones. If pregnancy does occur, human chorionic gonadotropin (hCG) takes over the function of luteinizing hormone (LH) and, in contrast to LH, extends the functional life span of the CL. In this study, we investigated the effects of hCG and LH in a spheroidal cell culture model of CL development. Our data indicate that GCs secrete factors under the control of hCG that increase sprout formation of EC-spheroids. We demonstrate that the most prominent of these factors is VEGF-A. Furthermore, we found that both LH and hCG decrease sprout formation of GC-spheroids. After forming EC-GC coculture spheroids and consequently bringing GCs and ECs in close contact, sprouting increased under the influence of hCG, however not under LH. These experiments provide evidence for an hCG dependent functional switch in the GCs after coming in contact with ECs. Moreover, it demonstrates the considerably different effects of hCG and LH on GCs although their signaling is transmitted via the same receptor.

Cells, Cultured↗
PubMed2005

Recombinant gonadotrophins in reproductive medicine: gold standard for ovarian stimulation therapy in the 21st century.

The clinical use of gonadotrophin preparations started in the 1960s when it was possible to extract human menopausal gonadotrophins from urine of post-menopausal women. Recombinant gonadotrophins became available in 1995. Whereas in other therapeutic areas the introduction of pure, recombinant preparations such as insulin and growth hormone has lead to rapid phasing out of biological extraction-based therapies, this is different for gonadotrophins. It is difficult to understand why even today women are exposed to urinary products although the benefits of recombinant gonadotropohins in terms of safety are obvious.

Female↗
PubMed2004

Chorionic gonadotropin regulates the transcript level of VHL, p53, and HIF-2alpha in human granulosa lutein cells.

The ovarian corpus luteum plays a critical role in reproduction being the primary source of circulating progesterone. After ovulation the corpus luteum is build by avascular granulosa lutein cells through rapid vascularization regulated by gonadotropic hormones. The present study was performed to investigate whether this process might be influenced by the human chorionic gonadotropin (hCG)-dependent expression of different tumor suppressor genes and hypoxia dependent transcription factors. RNA was isolated from cultured granulosa lutein cells, transcribed into cDNA, and the transcript level of following genes were determined: RB-1, VHL, NF-1, NF-2, Wt-1, p53, APC, and hypoxia inducible factor-1 (HIF-1), -2, and -3alpha. Additionally, the influence of hCG on the expression of VHL, p53, and HIf2alpha were investigated. We demonstrate that in human granulosa lutein cells the tumor suppressor genes RB-1, VHL, NF-1, NF-2, Wt-1, p53, and APC and the hypoxia dependent transcription factors HIF-1alpha, -2alpha, and -3alpha are expressed. In addition, we showed that hCG regulates the expression of p53, VHL, and HIF-2alpha. Our results indicate that hCG may determine the growth and development of the corpus luteum by mediating hypoxic and apoptotic pathways in human granulosa lutein cells.

Apoptosis↗
PubMed2004

[Hystero-salpingo-contrast-sonography with 3-d-ultrasound -- a pilot study].

UNLABELLED: Hystero-salpingo-contrast sonography (HyCoSy) is a sensitive method of assessing tubal patency but cannot completely substitute diagnostic laparoscopy with blue dye and hysteroscopy. Three-dimensional sonography has new imaging facilities which could lead to a reduction of invasive diagnostic procedures. AIM: The aim of this pilot study was to analyse the feasibility of HyCoSy by 3D- and 3D-Doppler-sonography. METHODS: In a prospective setting conventional (2D) HyCoSy was performed in 21 patients with an ultrasound device designed for 3D-ultrasound. After the completion of the 2D procedure, 3D-ultrasound was carried out. In five patients an additional 3D-Doppler-HyCoSy was performed. The generated 3D-volumina were then examined. Laparoscopy with blue dye was performed immediately after the ultrasound examination. RESULTS: A total of 42 Fallopian tubes was assessed. On 2D-ultrasound, visibility of the tubes was excellent in 28 and limited in seven tubes. Of the seven tubes not visible on 2D-ultrasound, four were not patent on laparoscopy. On 3D-ultrasound, visibility of the tubes was excellent in 15 and limited in twelve tubes. 15 tubes were not visible on 3D-ultrasound. 3D-Doppler-HyCoSy revealed excellent assessment in eight of ten tubes, even in one of those with limited visibility on 2D- and 3D-HyCoSy. In 19 patients the assessment of the uterine cavity was excellent by 2D- and 3D-HyCoSy, whereas it was limited in two patients. CONCLUSION: It is possible to visualise the full length of the tubes in a very detailed way from the uterine cavity to the fimbrial end in some patients, but the diagnostic power of HyCoSy is not improved by adding 3D-imaging. The accuracy of 3D-ultrasound seemed to be improved by 3D-Doppler-ultrasound.

Fallopian Tubes↗
PubMed2004

PKA- and PKC-dependent regulation of angiopoietin 2 mRNA in human granulosa lutein cells.

New blood vessels develop from preexisting vessels in response to growth factors or hypoxic conditions. Recent studies have shown that angiopoietin 2 (ANGPT-2) plays an important role in the modulation of angiogenesis and vasculogenesis in humans and mice. The signaling pathways that lead to the regulation of ANGPT-2 are largely unclear. Here, we report that protein kinase C and protein kinase A activators (ADMB, 8-Cl-cAMP) increased the mRNA levels of ANGPT-2 in human Granulosa cells, whereas PKC and PKA Inhibitors (Rp-cAMP, GO 6983) decreased markedly the level of ANGPT-2 mRNA. Due to varying specificity of the modulators for certain protein kinases subunits, we conclude that the conventional PKCs, but not PKC alpha and beta1, the atypical PKCs and the PKA I, are involved in the regulation of ANGPT-2. These findings may help to explain the role of both PKA and PKC dependent signaling cascades in the regulation of ANGPT-2 mRNA.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2004

Differential regulation of ANG2 and VEGF-A in human granulosa lutein cells by choriogonadotropin.

The growth and development of the corpus luteum after rupture of the follicle is a highly regulated process characterised by a rapid vascularization of the follicle surrounding granulosa cells. Vascularization is regulated by a large number of growth factors and cytokines whereas members of the angiopoietin family and VEGF-A are reported to play a principal role. The gonadotropic hormones luteinizing hormone and choriogonadotropin are reported to be essential for corpus luteum formation. In this study we investigated by RT PCR if the growth factors PGF, PDGF-A, PDGF-B, VEGF-A, VEGF-B, VEGF-C, VEGF-D, ANG1, ANG2, ANG3 and ANG4 are expressed in granulosa cells. We show the expression of VEGF-A, VEGF-B, PDGF-A, ANG1 and ANG2 in granulosa cells. Using RT-PCR and Real-Time PCR we demonstrate that angiopoietin 2 is downregulated in human granulosa cells in vitro after choriogonadotropin treatment whereas the expression of angiopoietin 1 is not significantly altered. The expression of VEGF on the RNA- and on the protein level was determined. It was shown that in granulosa cells VEGF is upregulated after choriogonadotropin treatment on the RNA level and that increasing concentrations of choriogonadotropin from 0 to 10 U/ml leads to an increasing amount of VEGF in the cell culture supernatants. The amount of VEGF in the supernatants reaches a plateau at 0.5 U/ml and is increased only slightly and not significantly after treatment of the cells with 10 U/ml choriogonadotropin compared to 0.5 U/ml. In total these findings suggests that in granulosa cells the mRNA of various growth factors is detectable by RT-PCR and that VEGF-A and ANG2 is regulated by the gonadotropic hormone choriogonadotropin. These findings may add impact on the hypothesis of choriogonadotropin as a novel angiogenic factor.

Angiopoietin-1↗
PubMed2004

The size of a microsatellite polymorphism of the haem oxygenase 1 gene is associated with idiopathic recurrent miscarriage.

Endothelial damage, impaired microvascularization and immune maladaptation have been described as aetiological factors in recurrent miscarriages. We investigated the relationship between idiopathic recurrent miscarriage (IRM) and a (GT)(n) repeat microsatellite polymorphism of the gene encoding haem oxygenase 1 (HO-1), known to modulate immune functions such as T-helper (TH) cell function and to be associated with cardiovascular disease. We investigated 162 women with IRM and 129 healthy, post-menopausal controls. The length of the HO-1 (GT)(n) microsatellite was assessed by PCR and direct sequencing in all women. Results were correlated with clinical data. The distribution of genotypes was in Hardy-Weinberg equilibrium. The HO-1 (GT)(n) microsatellite repeat numbers ranged from 13 to 37, with (GT)(23) and (GT)(30) being the most common alleles in both groups. We compared alleles consisting of < or =27 GT repeats, termed class S (short) alleles and alleles consisting of >28 GT repeats, termed class L (long) alleles. Seventy per cent of women with IRM had an S allele either in heterozygous (L/S) or homozygous (S/S) form, compared to 56% of controls (P = 0.02; OR 0.54; 95% CI 0.32-0.90). With respect to S allele frequencies, we found no significant difference among women with IRM and controls [P = 0.3; odds ratio (OR) 1.23, 95% confidence interval (CI) 0.86-1.76]. Comparing women with primary and secondary IRM, no difference with respect to the length of the HO-1 (GT)(n) microsatellite was ascertained. In summary, this is the first report on a HO-1 (GT)(n) microsatellite polymorphism among women with IRM, demonstrating that the investigated polymorphism is associated with IRM in a relatively large Caucasian population.

Abortion, Habitual↗
PubMed2003

Impaired dynamic cerebral autoregulation in eclampsia.

Eclampsia is frequently associated with brain edema, cerebral infarction or hemorrhage. Its underlying cerebrovascular pathophysiology is still poorly understood. We examined cerebral autoregulation by a non-invasive multimodal assessment in a 28-year-old primaparous woman with postpartal eclampsia. Transcranial Doppler sonography showed considerably increased cerebral blood flow velocity (CBFV) of all basal cerebral vessels. Magnetic resonance imaging demonstrated multifocal vasogenic brain edema. Using transfer function analysis, a severely decreased phase shift between respiratory-induced 0.1-Hz oscillations of arterial blood pressure and CBFV was observed, indicating substantial disturbance of dynamic cerebral autoregulation (DCA). In contrast, CO(2)-vasomotor reactivity of the right middle cerebral artery was only slightly reduced. We therefore assume that the cerebral arteriolar dysfunction in eclampsia leads primarily to an impairment of the autoregulatory mechanism that is followed by different degrees of arteriolar vasodilation. Because of its probably high sensitivity to hemodynamic disturbances, assessment of DCA might be of great value in early pre-eclampsia for risk prediction of cerebral arteriopathy and eclampsia.

Adult↗
PubMed2002

[Physiology of ovarian function].

The ovarian function including follicular maturation, ovulation and corpus luteum formation is regulated by a complex control system composed of hypothalamus, pituitary and the ovary itself. These organs communicate via positive and negative feedback loops and can be considered as a functional entity. Special neurons in the hypothalamus produce gonadotropin-releasing hormone (GnRH) being delivered to the anterior pituitary lobe by the pituitary portal vessels. GnRH binds to specific receptors inducing synthesis and release of the gonadotropins FSH and LH into the circulation. After binding to their specific receptors at the ovary FSH and LH induce follicular maturation, ovulation and corpus luteum formation. The ovary responds to gonadotropin stimulation in dual fashion: secretion of sexsteroids and the liberation of a fertilizable oocyte. In addition the ovary is also able to secrete peptide-hormones such as inhibin and activin. Sexsteroids and inhibin modulate the pulsatile secretion of GnRH and gonadotropins. Cooperation of theca- and granulosa cells at the ovarian level and the corpus luteum formation are described and the significance of growth factors and cytocines is emphasized. The effects of estradiol and progesterone are highlighted by the morphological response of the endometrium. The ovary is actively involved in maintaining cyclicity, as reflected by the processes of follicular growth, follicle rupture and formation of the corpus luteum with the dramatic morphological changes involved.

Animals↗
PubMed2002

[The corpus luteum].

The primary function of the corpus luteum is secretion of progesterone for maintenance of pregnancy. The development and function of the corpus luteum from residual follicular granulosa and theca cells after ovulation is induced by the midcyclic peak of LH secretion followed by further pulsatile LH release. Due to this stimulation the follicular granulosa and theca cells are converted to large and small luteinized cells with high proliferation rate. During this process Vascular-Endothelial-Growth Factor (VEGF) plays a major role as a potent stimulator of neo-angiogenesis. Formation of new blood vessels is essential to ensure supply of LDL-Cholesterol as substrate for steroidogenesis. If pregnancy does not occurs, the corpus luteum must regress to initiate another cycle. Luteal regression seems to be initiated by PGF2 alpha which is secreted from the uterus. PGF2 alpha, reduces luteal blood flow and progesterone synthesis. Furthermore it is a potent inducer of apoptosis. If pregnancy occurs, sustained secretion of progesterone and other substances like estradiol and relaxin are required to provide an appropriate uterine environment for maintenance of pregnancy. In that case the corpus luteum is further stimulated by hCG secreted by the blastocyst and the trophoblast-cells until 8/9 weeks of gestational age, when synthesis and secretion of steroids is taken over by the placenta.

Corpus Luteum↗
PubMed2002

[Predictive factors for determination of menopausal age].

In western Europe the average age at menopause is 52 years. This means that a woman spends approximately 30 years of her life in the postmenopausal status. The possibility to predict the actual age AT menopause would have major implications for family planning, sterility treatment and for the decision to apply HRT. There are numerous associations between socio-economic factors and the age at menopause. A positive correlation has been shown between cigarette smoking and menopausal age. Furthermore several lifestyle factors have an influence on the onset of menopause. However it is not clear in how far generative and socio-economic factors such as marital status interfere with ovarian function.

Age Factors↗
PubMed2002

[Premature climacteric as a special form of secondary ovarian insufficiency].

In western countries menopause is expected to occur at 50-52 years of age. Cessation of ovarian function before the age of 40 is defined as premature ovarian failure (POF). POF can be associated with chromosomal aberrations as well as with autoimmune diseases or general endocrine or metabolic disorders. Prevalence of POF is significantly increased in patients undergoing chemotherapy or radiation for treatment of malignant diseases. In some patients however etiology of POF remains unknown. Therefore therapeutic options are limited. For counseling patients it cannot be over-emphasized that HRT is mandatory to prevent long term symptoms of estrogen deprivation.

Adult↗
PubMed2001

Soluble VEGFR-1 secreted by endothelial cells and monocytes is present in human serum and plasma from healthy donors.

It was shown before that the soluble form of VEGFR-1 (sVEGFR-1) is present in serum of pregnant women. The aim of the present study was to investigate the presence of this endogenous vascular endothelial growth factor-A (VEGF-A) antagonist in human serum in more detail. sVEGFR-1 was detected in human serum and plasma from normal healthy male and female donors by ELISA. sVEGFR-1 levels ranged from non-detectable up to 440 pg/ml, with no significant difference between male and female donors. In addition, vein endothelial cells (ECs) from an intact vascular bed, the umbilical cord, were shown to secrete sVEGFR-1. Furthermore, human peripheral blood monocytes, a non-EC type expressing VEGFR-1, were shown to contribute to the sVEGFR-1 detectable in human serum and plasma for the first time. EC- and monocyte-derived sVEGFR-1 proved capable of inhibiting the VEGF-induced proliferation and migration of ECs in vitro. Finally, secretion of sVEGFR-1 was increased by the angiogenic factor basic fibroblast growth factor (bFGF) in human ECs and was also enhanced in lipopolysaccharide-activated human monocytes. In human umbilical vein endothelial cells, both the membrane-bound and the sVEGFR-1 seem to be equally regulated on the mRNA as well as the protein level. The presence of an sVEGFR-1 in human serum and plasma of normal male and female donors strongly suggests that it plays an important role as a naturally occurring VEGF antagonist in the regulation and availability of VEGF-mediated biological activities in vivo.

Base Sequence↗
PubMed1999

Comprehensive and definitive molecular cytogenetic characterization of HeLa cells by spectral karyotyping.

We revisited the cytogenetic alterations of the cervical adenocarcinoma cell line HeLa through the use of spectral karyotyping (SKY), comparative genomic hybridization (CGH), and fluorescence in situ hybridization (FISH). SKY analysis unequivocally characterized all abnormal chromosomes. Chromosomal breakpoints were primarily assigned by simultaneous assessment of SKY painted chromosomes and inverted 4,6-diamidino2-phenylindole banding from the same cell. Twenty clonally abnormal chromosomes were found. Comparison with previously reported HeLa G-banding karyotypes revealed a remarkably stable cytogenetic constitution because 18 of 20 markers that were found were present before. The classification of 12 markers was refined in this study. Our assignment of the remaining six markers was consistent with those described in the literature. The CGH map of chromosomal copy number gains and losses strikingly matched the SKY results and was, in a few instances, decisive for assigning breakpoints. The combined use of molecular cytogenetic methods SKY, CGH, and FISH with site-specific probes, in addition to inverted 4,6-diamidino-2-phenylindole or conventional G-banding analysis, provides the means to fully assess the genomic abnormalities in cancer cells. Human papillomaviruses (HPVs) are frequently integrated into the cellular DNA in cervical cancers. We mapped by FISH five HPV18 integration sites: three on normal chromosomes 8 at 8q24 and two on derivative chromosomes, der(5)t(5;22;8)(qll;q11q13;q24) and der(22)t(8; 22)(q24;q13), which have chromosome 8q24 material. An 8q24 copy number increase was detected by CGH. Dual-color FISH with a c-MYC probe mapping to 8q24 revealed colocalization with HPV18 at all integration sites, indicating that dispersion and amplification of the c-MYC gene sequences occurred after and was most likely triggered by the viral insertion at a single integration site. Numerical and structural chromosomal aberrations identified by SKY, genomic imbalances detected by CGH, as well as FISH localization of HPV18 integration at the c-MYC locus in HeLa cells are common and representative for advanced stage cervical cell carcinomas. The HeLa genome has been remarkably stable after years of continuous cultivation; therefore, the genetic alterations detected may have been present in the primary tumor and reflect events that are relevant to the development of cervical cancer.

Chromosome Aberrations↗