G. Bernaschek

Three dimensional ultrasound: abnormalities of the fetal face in surface and volume rendering mode

Objective To evaluate three dimensional ultrasound in surface and volume rendering mode in fetal malformations of the face.

A role of the tuberous sclerosis gene-2 product during neuronal differentiation

Tuberous sclerosis is an autosomal dominant disorder. Besides the development of benign growths (hamartomas) in different tissues, one hallmark of this disease is the presence of highly epileptogenic dysplastic lesions in the cerebral cortex (tubers) composed of abnormal shaped neurones. Patients often show evidence of severe mental retardation. Linkage analysis revealed two disease-determining genes on chromosome 9 and chromosome 16. The TSC2 gene on chromosome 16 encodes a 1784-amino acid putative tumour suppressor protein, tuberin, that functions as a GTPase-activating protein. Here we show that tuberin expression is upregulated upon induction of neuronal differentiation in the neuroblastoma cell lines SK-N-SH and LAN-1. This upregulation occurs at post-transcriptional level and is independent of the proliferation status. TSC2 expression is unaffected during differentiation of C2C12 myoblasts into myotubes and of F9 embryonal carcinoma cells into cells resembling parietal endoderm. Antisense inhibition of tuberin expression in SK-N-SH or LAN-1 cells inhibits neuronal differentiation, but does not affect the differentiation of F9 cells. Ectopic overexpression of TSC2 not only reverts the antisense-associated phenotype but furthermore accelerates the neuronal differentiation process. Our data show for the first time that tuberin plays a critical role in neuronal differentiation. Such role is consistent with the phenotype of tuberous sclerosis patients, who inherit one defective TSC2 allele, and frequently lose the remaining normal allele in many of the tubers/hamartomas which develop in the central nervous system of these patients.

Vaginal sonography versus serum human chorionic gonadotropin in early detection of pregnancy

We first performed a vaginosonic scan and then determined the serum human chorionic gonadotropin (beta-hCG) concentration (Second International Standard) in 52 women at an early gestational age to establish criteria for the earliest possible identification of an intrauterine pregnancy by this new ultrasound technique. The smallest diameter of a gestational sac detected was 2 mm, and the lowest beta-hCG concentration was 141 mIU/ml when an intrauterine pregnancy was correctly diagnosed. Between 50 and 280 mIU/ml, six out of eight pregnancies in this range were not seen. However, all pregnancies associated with beta-hCG concentrations greater than 300 mIU/ml were correctly identified. Taking into account the rapid growth of the conceptus and the exponential increase of serum beta-hCG by a factor of 1.7 per day at this early gestational age, we presume that a gestational sac at beta-hCG concentrations of 750 mIU/ml should not be missed by vaginosonography (safety margin of the discriminatory zone), even in instances of a retroverted uterus. No false-positive vaginosonographic findings were observed in this study. A vaginosonographic examination is a short and well-tolerated procedure that can be performed in a physicians office. The use of a 5 MHz transducer placed in the vagina provides better resolution and image quality. This overcomes imperfect anatomy and other physical factors that interfere with good imaging. The vaginosonographic examination provides information on the anatomic location of the gestational sac, with the highest reliability and accuracy around the time a woman misses her menstrual period. It can be very useful in the differential diagnosis of an ectopic pregnancy.

Vaginosonography for recording of cycle-related myometrial contractions.

It has been recognized from experimental or invasive studies that the nonpregnant human uterus has an inherent contractibility. We used vaginosonography for imaging contractions of the inner third of the myometrium. The direction, frequency, and symmetry of contractions were noted. We studied 53 women and subdivided them into four groups based on the cycle phase. During menstruation we found contractions toward the cervix with irregular frequency varying between 1 and 3/min. In the periovulatory period we noted the highest frequency of 10/min of regular contractions toward the fundus. The results showed that active myometrial contractions can be detected sonographically throughout the whole menstrual cycle. Increased myometrial contractions toward the fundus in the periovulatory period may be involved in sperm transport to the tubes.

Activation of c-Myc uncouples DNA replication from activation of G1-cyclin-dependent kinases

Proto-oncogenes like c-myc are thought to control exit from the cell cycle rather than progression through the cell cycle itself. We now present a different view of Myc function. Exponentially growing Rat1-MycERTM fibroblasts were size-fractionated by centrifugal elutriation. In these cells, activation of cyclin E- and cyclin A-dependent kinases, degradation of p27, hyperphosphorylation of retinoblastoma protein and activation of E2F occur sequentially at specific cell sizes. Upon activation of Myc, however, these transitions all occur simultaneously in small cells immediately after exit from mitosis. In contrast, Myc has no discernible effect on the cell size at which DNA replication is initiated. These data show first that Myc controls the activity of G1 cyclin-dependent kinases independently from the transition between quiescence and proliferation and from any effect on cell growth in size. These data also provide evidence of at least one dominant mechanism besides activation of E2F and of cyclin E/cdk2 kinase, which prevents DNA replication unless a critical cell size has been reached.

Brca1 regulates in vitro differentiation of mammary epithelial cells

Murine Brca1 is widely expressed during development in different tissues. Why alterations of BRCA1 lead specifically to breast and ovarian cancer is currently not clarified. Here we show that Brca1 protein expression is upregulated during mammary epithelial differentiation of HC11 cells, during differentiation of C2C12 myoblasts into myotubes and during neuronal differentiation of N1E-115 cells. Ectopic overexpression of BRCA1 and downregulation of endogenous Brca1 expression specifically affect the regulation of mammary epithelial cell differentiation. Accelerated mammary epithelial cell differentiation upon high ectopic BRCA1 expression is not a consequence of the anti-proliferative capacity of this tumor suppressor and independent of functional p53. Overexpression of the BRCA1 variant lacking the large central exon 11 has no effects on mammary epithelial cell differentiation. These data provide new insights into the cellular role of Brca1.

Transvaginal pulsed Doppler measurement of blood flow velocity in the ovarian arteries during cycle stimulation and after follicle puncture

In experimental studies, an increase of the ovarian blood flow was found during cycle stimulation. In this study, the authors performed transvaginal pulsed Doppler measurements of the ovarian arteries in stimulated cycles before and after follicle puncture. Four days before follicle puncture, high flow velocities in systolis were found compared with diastolis. Toward the day of embryo transfer, a marked increase of the diastolic blood flow velocity was observed. In patients with high endocrine response, the pulsatility index (PI) was significantly lower compared with that of patients with low endocrine response. The technique of transvaginal pulsed Doppler measurements offers the possibility to study the alterations of the ovarian blood flow under physiologic and pathophysiologic conditions.

Endometrial volume change during spontaneous menstrual cycles : volumetry by transvaginal three-dimensional ultrasound

OBJECTIVE At present, only limited data are available on endometrial volume during the menstrual cycle. Most of these studies deal with animal models and use magnetic resonance imaging for volume measuring. The application of three-dimensional ultrasound in endometrial volume estimation is the subject of this study. SETTING Patients visiting the outpatient unit of the division of endocrinology and reproductive medicine of a university hospital. PATIENT(S) Twenty patients with a history of a normal menstrual cycle were selected. INTERVENTION(S) Ultrasound examinations were performed during a single menstrual cycle in addition to routine laboratory tests. MAIN OUTCOME MEASURE(S) Uterus-endometrial volume ratio. RESULT(S) Data from 18 patients could be evaluated. In 81 examinations the endometrium volume could be determined. Mean endometrial volume measured by three-dimensional ultrasound was 1.23 cm3. Mean uterus volume was 48.93 cm3. The change of the uterus-endometrial volume ratio showed a good correlation with the day of menstrual cycle. Quadratic regression analysis of volume and cycle length was R2 = 0.432. CONCLUSION(S) Three-dimensional ultrasound allows assessment of volume data of the female internal genitalia. In this study changes of the endometrial volume in menstrual cycles were measured. Additional studies are required to give information on the clinical impact of this new technique of endometrial volume estimation.

Fetal kidney volume and urine production in cases of fetal growth retardation

The amount of amniotic fluid has a close correlation to the function of the fetal renal system. In many cases of fetal growth retardation oligohydramnios is obvious. The aim of this study is the investigation of the hourly fetal urine production rate (HFUPR) and the growth of fetal kidneys during pregnancy in cases of fetal growth retardation and to evaluate the renal participation in the origin of oligohydramnios in cases of growth retardation. In 52 healthy pregnancies and 27 cases with known fetal growth retardation, the volume of the fetal kidneys was measured sonographically and the hourly rate of fetal urine production was determined. Two third of the patients with fetal growth retardation had obvious oligohydramnios. In cases of fetal growth retardation the volume of the fetal kidneys was significantly smaller when compared to the control group, and the volume of fetal urine production was significantly lower. The reduced perfusion of the fetal kidneys in those cases with fetal growth retardation may be the reason for the reduction of the HFUPR. Due to the fact that HFUPR is a dynamical parameter and in close relationship to the perfusion of the fetal kidneys, the identification and measurement of this parameter may help to detect subacute and imminent fetal distress in cases of sonographically proven fetal growth retardation.

Male fetuses are particularly affected by maternal alloimmunization to D antigen.

BACKGROUND: It is hypothesized that male fetuses are more severely affected by fetomaternal alloimmunization to D antigen than female fetuses.