Biomedical subjects

Martin Knöfler

Publications and source records attributed to Martin Knöfler.

8 recordsLinked to original sources

PubMed2003

Elevated serum concentrations of androgens in women with pregnancy-induced hypertension.

Alterations of steroid hormone profiles have been suggested to be involved in the pathophysiology of pregnancy-induced hypertension (PIH). The aim of our study was first to investigate serum concentrations of testosterone, dihydrotestosterone, androstenedione and dehydroepiandrostenedione sulfate in women with PIH and normotensive pregnant women and secondly to evaluate an association between elevated serum concentrations of androgens and the development of severe disease. Serum concentrations of androgens were measured in 40 patients with PIH and 40 normotensive pregnant women, matched for gestational age, determined by enzyme linked immunosorbent assay. Multivariate logistic regression models were used to analyze the influence of elevated serum concentrations of androgens on the occurrence of PIH and the development of severe disease. The median serum concentrations of androstenedione and testosterone were significantly elevated in women with PIH compared to controls (6.3 and 5.0 ng/ml, 1.8 and 1.1 ng/ml, p = 0.005 and p = 0.04, respectively). The difference between the median serum concentrations of dihydrotestosterone and dehydroepiandrostenedione sulfate in women with PIH and controls was not significant. Elevated serum concentrations of androstenedione revealed a significant influence on the odds of presenting with PIH (p = 0.043) and were significantly associated with the development of severe disease (p = 0.014). Women with PIH have elevated serum concentrations of androstenedione and testosterone. Moreover, elevated serum concentrations of androstenedione are associated with development of severe disease.

Adult↗

PubMed2003

Expression of the human Hand1 gene in trophoblastic cells is transcriptionally regulated by activating and repressing specificity protein (Sp)-elements.

The tissue-specific basic helix-loop-helix protein Hand1 is essential for the formation of trophoblast giant cells of the murine placenta. In humans, Hand1 is detectable in trophoblastic tumour cells suggesting an equivalent role in trophoblast differentiation. To understand its mode of expression we have cloned and characterized the human Hand1 gene promoter. Primer extension analyses suggest that transcription initiates 19 nucleotides downstream of the TATA element of the proximal 5' flanking region. Expression of luciferase reporter constructs harboring deletions of the 9.5 kb Hand1 5' flanking sequence defines a promoter region within 274 bp upstream of the transcriptional start site. Compared to a reporter bearing only the TATA box, the proximal promoter activates transcription up to 30-fold. However, transcriptional activity of the region was observed in both Hand1-expressing and non-expressing cell lines. Sequencing, DNAseI footprint analyses and electrophoretic mobility shift assays reveal the presence of four GC-rich sequences, which show different affinities to the endogenous specificity proteins (Sp), and a CCAAT box. In vitro, the Sp-elements mainly interact with Sp1 and Sp3 while the CCAAT element is recognized by the alpha CAAT binding factor protein. Mutant luciferase reporters bearing single active or inactive recognition sites demonstrate that two of the four Sp-binding sites (I and IV) contribute little to the overall transcription rate. The two other Sp-cognate sequences, II and III, downregulate and activate reporter expression 2.3- and 2.6-fold, respectively. Co-transfections of Sp1/Sp3 expression vectors and mutated reporter constructs in Sp-deficient SL2 cells indicate that the Sp-binding site II and III indeed function as repressing and activating enhancer sequences. In summary, the data suggest that constitutive expression of the Hand1 gene in cultured cells is regulated by a complex interplay of Sp-proteins interacting with activator and repressor elements.

5' Flanking Region↗

PubMed2002

Redistribution of corticotropin-releasing hormone receptor R2 using fluorescence immunohistochemistry in fetal membranes of women delivering preterm or at term.

OBJECTIVE: The aim of our study was to determine whether a difference exists in expression of corticotropin-releasing hormone receptor-R1 (CRH-R1) and corticotropin-releasing hormone receptor-R2 (CRH-R2) in fetal membranes of preterm and term women with or without labor. MATERIAL AND METHODS: Small pleces of fetal membranes were obtained from the placenta of each of forty patients undergoing cesarean section. Ten samples each were taken from preterm and term patients, with and without labor. Antibodies against CRH-R1/2 and CRH-R2 were used for localization by conventional fluorescence immunohistochemistry. The evaluation of staining was based on examination of the entire histologic section by three independent observers. RESULTS: In women at term without labor, CRH-R2 receptor was predominantly expressed in the amniotic epithelium and the amniotic mesenchyme. In laboring women at term, the expression of CRH-R2 receptor was shown in the chorionic mesenchyme and the cytotrophoblast cells, but no specific staining could be detected in the amniotic membranes. Changes in CRH-R2 receptor expression could not be demonstrated during preterm labor of early pregnancies. In preterm women, the antibody against CRH-R1/2 receptor detected additional signals in the amniotic mesenchyme and epithelium, suggesting expression of CRH-R1 in these tissues. In women at term, the overlapping pattern of CRH-R1/2 was recognized in both the chorionic and amniotic mesenchyme, in contrast to the specific CRH-R2 staining, suggesting expression of CRH-R1 in the mesodermal cell compartments. CONCLUSION: At term, changes in CRH-R2 expression are directly related to the progression of normal labor; such changes were not observed during preterm labor of early pregnancies. The increased CRH-R2 expression in the chorionic mesenchyme may possibly provoke rupture of the membranes or at least play a role in some key regulatory events in the initiation of normal labor. The fact that this mechanism does not occur in preterm labor strengthens the hypothesis that onset of labor could be controlled by distinct mechanisms in preterm and term pregnancies.

Amnion↗

PubMed2002

Serum levels of heat shock protein 70 in patients with preeclampsia: a pilot-study.

OBJECTIVE: To evaluate the serum levels of heat shock protein (Hsp) 70 in patients with severe preeclampsia (PE) in comparison to controls. The pathophysiology of PE can be explained, in part, by alterations of endothelial function caused by endothelial cell activation and injury. HSP 70 is essential for cellular recovery, survival and maintenance of homeostasis. STUDY DESIGN: In a matched pair study, serum levels of Hsp 70 were measured in 55 patients with late (group A, n = 24) and early (group B, n = 31) onset of severe PE, and in 55 normotensive controls (group C, n = 24 and group D, n = 31) matched for gestational age. Early onset of severe PE was defined as onset of disease at less than 34 weeks of gestation (34 + 0). Serum levels were determined using a sandwich enzyme-linked immunosorbent assay. RESULTS: The overall median serum levels of Hsp 70 were 2.82 ng/mL (SD +/- 8.33) in preeclamptic women, and 1.01 (SD +/- 1.38) ng/mL in controls (P = 0.08). The median serum levels of Hsp 70 were 0.52 ng/mL (SD +/- 1.14) in group A and 0.86 (SD +/- 1.29) ng/mL in group C (P = 0.15). The median serum levels of Hsp 70 were 4.94 ng/mL (SD +/- 10.46) in group B and 1.33 (SD +/- 2.28) ng/mL (P = 0.04) in group D. The difference between group A and B was also statistically significant (P = 0.01). CONCLUSION: Our study revealed higher serum levels of Hsp 70 in patients with early onset of severe PE. Further studies are recommended in order to elucidate the possible role of Hsp 70 in the pathophysiology of PE.

Adult↗

PubMed2002

Concentrations of estrogens in patients with preeclampsia.

The role of estrogens in the pathophysiology of preeclampsia remains to be determined. The aim of our study was to compare serum concentrations of 17 beta-estradiol and estriol in women with preeclampsia to normotensive pregnant controls. Serum concentrations of estrogens were measured in women with mild (n = 24) and severe (n = 24) preeclampsia as well as is normotensive pregnant controls (n = 24). Patients were matched for gestational age. Pregnancies complicated by early onset severe preeclampsia are associated with increased rates of maternal and fetal morbidity. Subsequently, we created further subgroups before and after 34 weeks of gestation (34 + 0). Serum estrogen concentrations were determined by standard ELISA technique. Compared to normotensive controls, the differences between the overall median serum concentrations of 17 beta-estradiol in women with mild (3811 v. 3730 pg/ml, P = 0.9) and severe (3811 v. 3630 pg/ml, P = 0.1) preeclampsia were statistically not significant. The differences between the overall median serum concentrations of estroil in controls and in patients with mild (121 v. 76 ng/ml, P = 0.6) and severe (121 v. 79 ng/ml, P = 0.4) preeclampsia were similar. The differences between the median concentrations of 17 beta-estradiol in patient with early onset severe preeclampsia compared to patients with mild preeclampsia (3061 v. 3715 pg/ml, P = 0.004) and controls (3061 v. 3807 pg/ml, P = 0.006) were statistically significant. In addition, the differences between the median concentrations of estriol in women with early onset severe preeclampsia compared to controls were statistically significant (20 v. 92 ng/ml, P = 0.02). The differences between the median concentrations of estrogens in those with late onset severe preeclampsia compared to women with mild preeclampsia were not significant. We found significantly lower concentrations of estrogens in women with early onset severe preeclampsia.

Adult↗

PubMed2002

Human Hand1 basic helix-loop-helix (bHLH) protein: extra-embryonic expression pattern, interaction partners and identification of its transcriptional repressor domains.

The basic helix-loop-helix (bHLH) transcription factor, Hand1, plays an important role in the development of the murine extra-embryonic trophoblast cell lineage. In the present study, we have analysed the expression of Hand1 in human extra-embryonic cell types and determined its binding specificity and transcriptional activity upon interaction with different class A bHLH factors. Northern blotting and in situ hybridization showed that Hand1 mRNA is specifically expressed in amnion cells at different stages of gestation. Accordingly, we demonstrate that the protein is exclusively produced in the amniotic epithelium in vivo and in purified amnion cells in vitro using a novel polyclonal Hand1 antiserum. Reverse transcriptase-PCR and immunohistochemical staining of blastocysts revealed the production of Hand1 mRNA and polypeptide in the trophectodermal cell layer. In the presence of E12/E47, Hand1 stimulated the transcription of luciferase reporters harbouring degenerate E-boxes, suggesting that E-proteins are potential dimerization partners in trophoblastic tumour and amnion cells. In contrast, Hand1 diminished E12/E47-dependent transcription of reporters containing perfect E-boxes by inhibiting the interaction of Hand1/E-protein heterodimers with the palindromic cognate sequence. Furthermore, we show that Hand1 down-regulated GAL-E12-dependent reporter expression, indicating that the protein can also act directly as a transcriptional repressor. Mutational analyses of GAL-Hand1 suggested that two protein regions located within its N-terminal portion mainly confer the repressing activity. In conclusion, human Hand1 may play an important role in the differentiation of the amniotic membrane and the pre-implanting trophoblast. Furthermore, the data suggest that Hand1 can act as a repressor by two independent mechanisms; sequestration of class A bHLH factors from E-boxes and inhibition of their transcriptional activity.

Basic Helix-Loop-Helix Proteins↗

PubMed2002

Basic fibroblast growth factor and hypertensive disorders in pregnancy.

OBJECTIVE: We examined serum concentrations of basic fibroblast growth factor (bFGF) in women with hypertensive disorders in pregnancy and analyzed whether serum concentrations of bFGF can be used as a discriminator between mild and severe preeclampsia. METHODS: One hundred and twenty pregnant women were included in this prospective cohort study. We evaluated serum concentrations of bFGF in pregnant women with chronic hypertension (n=22), mild preeclampsia (n=40), severe preeclampsia (n=31), and healthy pregnant women (n=27). RESULTS: Median serum concentrations of bFGF in healthy pregnant women, women with chronic hypertension, and women with mild or severe preeclampsia were 0.0 (0-37.2), 0.0 (0-3.0), 1.7 (0-97.2), and 0.0 (0-52.0), respectively. Comparison of the median values of serum bFGF concentrations showed a significant difference between healthy pregnant women and women with mild preeclampsia (P=0.02). In a logistic regression model, we found a significant influence of bFGF serum concentrations on the diagnosis of mild preeclampsia (P=0.01), but not on the diagnosis of chronic hypertension (P=0.19) or severe preeclampsia (P=0.41). CONCLUSIONS: Elevated serum concentrations of bFGF are associated with mild preeclampsia, but are not discriminatory for the distinction between mild and severe preeclampsia.

Analysis of Variance↗

PubMedDate not supplied

Production of oxytocin receptor and cytokines in primary uterine smooth muscle cells cultivated under inflammatory conditions.

OBJECTIVE: We studied the production of the oxytocin receptor and interleukins in human uterine smooth muscle cells cultured in vitro in the presence of cytokines that were shown to be elevated in gestational diseases such as intrauterine infections and chorioamnionitis. METHODS: Human uterine smooth muscle cells were cultured in the absence or presence of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), tumor necrosis factor alpha (TNFalpha), or lipopolysaccharide (LPS). Additionally, cells were cultivated under hypoxic conditions (3.5% oxygen). After 6, 12, 24, and 48 hours of incubation, oxytocin receptor mRNA was measured from total RNA using quantitative, competitive reverse transcriptase-polymerase chain reaction. Secreted cytokines (IL-1beta, IL-6, or IL-8) were quantitated from supernatants after 6, 12, 24, and 48 hours of stimulation by commercially available enzyme-linked immunosorbent assay. RESULTS: In nonstimulated cultures basal secretion of IL-1beta, IL-6, and IL-8 was detectable. Supplementation of IL-1beta induced a statistically significant decrease in oxytocin receptor mRNA abundance, whereas IL-6, TNFalpha, LPS, or hypoxia did not significantly affect oxytocin receptor gene expression. The cytokines IL-1 and TNFalpha induced IL-6 and IL-8 release, whereas secretion of the two interleukins was not altered in the presence of LPS or hypoxia. Expression of IL-1beta was not significantly induced under inflammatory or hypoxic culture conditions. CONCLUSION: The constitutive and cytokine-inducible expression of interleukins from uterine smooth muscle cells suggests that the myometrium may contribute to the overall production of inflammatory mediators in the uterus that are thought to govern term- or infection-induced preterm labor. Down-regulation of the oxytocin receptor under IL-1beta in myometrial cells may indicate that initiation and maintenance of labor could be partially limited under severe inflammatory conditions such as chorioamnionitis.

Cells, Cultured↗