Biomedical subjects

G Weber

Publications and source records attributed to G Weber.

At least 199 records · Page 11Linked to original sources

PubMed1995

Inactivation of simian immunodeficiency virus by hydrostatic pressure.

The inactivation of the simian immunodeficiency viruses SIVmac251 and SIVagm by pressures of 150 and 250 MPa was determined. The extent of inactivation depended on the time that the virus was subjected to compression as well as the level of the pressure and at 150 Mpa reached 5 log10 dilution units after approximately 10 hr. The inactivations, which were uniformly carried out at room temperature, were independent of the concentration of the virus. Possible applications of pressure inactivation for molecular biological and clinical use are discussed.

Hydrostatic Pressure↗

PubMed1995

Phosphoinositide signaling in nuclei of Friend cells: tiazofurin down-regulates phospholipase C beta 1.

Previous investigations have demonstrated the presence of conventional lipid kinases and phospholipase C (PLC) activities in nuclei of Friend erythroleukemia cells. Moreover, when Friend erythroleukemia cells are treated for 96 h with the antitumor drug tiazofurin, the induction of erythroid differentiation is accompanied by changes in amounts of both phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate due to the inhibition of an uncharacterized nuclear PLC activity. Here, we show that the nuclear PLC beta 1 isoform is down-regulated by tiazofurin (5 microM) treatment of Friend erythroleukemia cells as shown by both Western blot and Northern blot analyses for PLC beta 1 message. This indicates that PLC beta 1 down-regulation is tightly linked with erythroid differentiation of Friend erythroleukemia cells and that the autonomous nuclear signaling via inositol lipid cycle can be controlled by the antitumor drug tiazofurin.

Animals↗

PubMed1995

Genomic organization and complete cDNA sequence of the human phosphoinositide-specific phospholipase C beta 3 gene (PLCB3).

We have characterized the complete cDNA sequence, genomic structure, and expression of the human phosphoinositide-specific phospholipase C beta 3 (PLC beta 3) gene (gene symbol PLCB3). PLC beta 3 plays an important role in initiating receptor-mediated signal transduction. Activation of PLC takes place in many cells as a response to stimulation by hormones, growth factors, neurotransmitters, and other ligands. The partial cDNA sequence of PLC beta 3, previously published, was extended with 876 bp in the 5' direction, giving a transcript of 4400 bp and a total open reading frame of 1234 amino acids. This was in accordance with expression analysis by Northern blotting that revealed a single 4.4-kb transcript in all tissues tested. Genomic data were obtained by sequencing plasmid subclones of a cosmid that contained the whole gene. The size of the complete transcription unit was estimated to be on the order of 15 kb. The gene contains 31 exons, with all splice donor and acceptor sites conforming to the GT/AG rule. No exon exceeds 571 bp in length, and the shortest exon spans only 36 bp. More than half of the introns are smaller than 200 bp, with the smallest being only 79 bp long. The transcription initiation site was determined to be within an 8-bp cluster 328-321 bp upstream of the translation initiation site. The 5'flanking region is highly GC rich, with multiple CpG doublets, and contains multiple binding sites for Sp1. Lacking typical transcriptional regulatory sequences such as TATA and CAAT boxes, the putative promoter region conforms to the group of housekeeping promoters.

Amino Acid Sequence↗

PubMed1995

Quercetin down-regulates signal transduction in human breast carcinoma cells.

Signal transduction activity was markedly elevated in cancer cells as shown by the increased activity of enzymes utilizing 1-phosphatidylinositol, PI (PI 4-kinase and PI-4-phosphate 5-kinase) for the production of the second messenger inositol 1,4,5-trisphosphate, IP3, in rat hepatomas (Cancer Res. 54: 2611;5574, 1994) and in human ovarian and breast carcinoma cells (Life Sci. 55:1487, 1994). Quercetin, a flavonoid, in human breast carcinoma MDA-MB-435 cells produced growth inhibition (IC50 = 55 microM) and cytotoxicity (LC50 = 26 microM). Quercetin inhibited PI kinase activity in extracts of breast carcinoma cells (IC50 = 6 microM) and in cultured cells (IC50 = 10 microM) with a minor inhibition of PIP kinase activity. IP3 concentration decreased in parallel with PI kinase activity. In time sequence studies quercetin in breast carcinoma cells brought down PI kinase and IP3 concentration in 60 min to 5 and 6%, respectively; PIP kinase activity was at 63% of controls. The results demonstrate for the first time in proliferating human breast carcinoma cells a reduction by quercetin of the increased capacity for signal transduction, thus providing a novel and sensitive target in cancer cells.

1-Phosphatidylinositol 4-Kinase↗

PubMed1995

Sodium chloride in separation medium enhances cell compatibility of free flow electrophoresis.

Free flow electrophoresis of cell suspensions in buffers containing sodium chloride was investigated using a modified procedure and the new apparatus Octopus PZE. The major methodical innovations are upward fluid flow, margin buffers flowing through the electrophoresis chamber at both sides of a central cell suspension buffer, adjacent to the electrode membranes, and a sample injection device which focuses the cells hydrodynamically to the middle of the chamber thickness. Mononuclear leukocytes, suspended in a buffer containing 35 mM NaCl, could be fractionated with the same accuracy as by conventional free flow electrophoresis, operated with a single NaCl-free chamber buffer. However, testing the vitality of separated cells with the help of the calcium indicator FURA2-AM clearly demonstrated the biological importance of the presence of a minimum amount of sodium chloride during cell electrophoresis. Only if at least 35 mM NaCl were present could an undisturbed cytosolic Ca2+ metabolism be maintained for the time of a free flow electrophoresis cell separation experiment.

B-Lymphocytes↗

PubMed1995

Free flow-isoelectric focusing of human cellular lysates as sample preparation for protein analysis.

A whole cell lysate of human cells was separated into 80 fractions according to the pI of proteins using free flow isoelectric focusing with carrier ampholytes. The resolution of the process was highly reproducible, with an overlap of fractions of less than 30%. A protein of a faint silver stained spot in two-dimensional gel electrophoresis (2-DE) could be enriched, yielding a Coomassie blue stained spot which could be further characterized by protein chemical methods. The enrichment of less abundant proteins from a complex crude cell extract was found to be a suitable tool for sample preparation and enrichment before applying proteins to 2-DE and reversed-phase high performance liquid chromatography.

Buffers↗

PubMed1995

Tiazofurin induces a down-modulation of ICAM-1 expression on K562 target cells impairing NK adhesion and killing.

Tiazofurin treatment of K562 leukemia cells in vitro depletes the metabolites of the guanylate biosynthetic pathway, inducing erythroid differentiation, that, in turn, alters the phenotypic profile. As a consequence, K562 cells possibly modify their interaction with immune cells. Here we describe the binding and killing activity of peripheral blood NK cells against differentiating K562 cells and the correlation between their altered binding capacity and ICAM-1 expression levels in differentiating K562 cells. We found that decreased percentages of NK (and T) cells were bound to differentiating K562 cells generating a decreased cytotoxic activity. This corresponded to decreased expression of ICAM-1, as detected by FACS analysis and Western blot. Erythroid differentiation, binding and killing reduction, and ICAM-1 down-modulation were completely abrogated by guanosine treatment. Tiazofurin causes a decrease in lymphocyte recognition and binding to K562 target cells. This can be ascribed to the down-modulation of ICAM-1 expression on target cells, which, therefore, can escape killing, acquiring a selective survival advantage.

Antigens, CD↗

PubMed1995

Exclusion of the 13-kDa rapamycin binding protein gene (FKBP2) as a candidate gene for multiple endocrine neoplasia type 1.

The MEN1 gene is considered to be a tumour suppressor gene and has been localised to a 1-Mb region of 11q13.1. In this study, we report the physical localisation of the 13-kDa FK506 and rapamycin binding protein gene (FKBP2) to the cosmid marker D11S750, which is located inside the MEN1 region of non-recombination. The product of this gene is involved in signal transduction and is thus a candidate cell growth regulator or tumour suppressor gene. Northern studies have revealed that FKBP2 is expressed in those tissues predisposed to hyperplasia in MEN1; however, single-strand conformation polymorphism analysis and direct sequencing of DNAs from affected members of MEN1 kindreds and sporadic tumour DNAs have been performed and no mutations have been found. These studies exclude FKBP2 as a candidate gene for MEN1.

Base Sequence↗

PubMed1995

Bone mineral metabolism and thyroid replacement therapy in congenital hypothyroid infants and young children.

Impairment of calcium metabolism and low bone density have been found in hypothyroid adults. We investigated the effect of thyroid replacement therapy on calcium metabolism and bone mineralization in congenital hypothyroid (CH) infants and children. One hundred and 16 Caucasian CH consecutive patients were studied and were grouped according to their age: 23 patients at diagnosis, 20 at 3 mo, 24 at 6 mo, 25 at 12 mo and 24 at 36 mo. Thyroid replacement therapy was started at an initial dose of 6-8 micrograms/kg/day of L-thyroxine, and then decreased progressively. Calcium, phosphorus, magnesium, alkaline phosphatase (AP), parathyroid hormone (PTH) and osteocalcin (BGP) were measured as calcium metabolism indices. Bone mineral content (BMC) was measured at the mid-portion of the right radius AP, PTH and BGP concentrations were significantly higher in subjects at 3 mo of age (p < 0.05). This rise coincided with the end of the period of maximum dosage of L-thyroxine. Mild asymptomatic hypercalcemia was observed in 20 patients. All the other indices did not differ between age groups. BMC values and BMC annual increment were not different from those calculated for age-matched controls. We found that L-thyroxine replacement therapy does not alter bone mineralization of CH infants and children. Only a transitory increase of osteoblastic function was observed after the first few months of therapy.

Bone Density↗

PubMed1995

Linkage of reduction in 1-phosphatidylinositol 4-kinase activity and inositol 1,4,5-trisphosphate concentration in human ovarian carcinoma cells treated with quercetin.

Quercetin inhibited 1-phosphatidylinositol (Pl) 4-kinase, EC 2.7.1.67 (Pl kinase) activity in a concentration-dependent manner (IC50 = 4 microM) in particulate extracts from human ovarian carcinoma. In OVCAR-5 cells quercetin produced growth inhibition (IC50 = 63 microM) and cytotoxicity (LC50 = 17 microM). The growth inhibition by quercetin was accompanied by an 80% decrease in Pl kinase activity and a 65% decrease in the concentration of the second messenger, inositol 1,4,5-trisphosphate (IP3). When human OVCAR-5 cells were plated and expressed their neoplastic proliferative program in the log phase, Pl kinase and Pl 4-phosphate 5-kinase, EC 2.7.1.68 (PIP kinase) activities coordinately increased to a peak of 5.8- and 4.5-fold, respectively. The results demonstrate for the first time inhibition by quercetin of the enhanced capacity for operation of signal transduction in human ovarian carcinoma cells, thus providing a novel target in cancer cells.

1-Phosphatidylinositol 4-Kinase↗

PubMed1995

Quercetin: synergistic action with carboxyamidotriazole in human breast carcinoma cells.

Quercetin, a plant flavonoid, blocks signal transduction pathways by inhibiting 1-phosphatidylinositol 4-kinase (EC 2.7.1.67, PI kinase) and 1-phosphatidylinositol 4-phosphate 5-kinase (EC 2.7.1.68, PIP kinase), resulting in a reduction of inositol 1,4,5-trisphosphate (IP3) concentration which decreases the release of calcium from intracellular sources. Carboxyamidotriazole (CAI), a novel anticancer agent, inhibits calcium entry into cells. Because both drugs reduce cytosolic calcium levels, we tested the action of quercetin and CAI in human carcinoma cells. Human breast carcinoma MDA-MB-435 cells were grown in minimum essential medium with 10% fetal bovine serum. In growth inhibition assay the IC50s for quercetin and CAI were 55 and 4.8 microM, respectively; in clonogenic assay, 28 and 1.4 microM, respectively. When quercetin and CAI were added to the cultures, synergism was observed in isobolograms in growth inhibition and clonogenic assays. In growth inhibition assay, the best combination was 20 microM quercetin with 4 microM CAI; in clonogenic assay, 30 microM quercetin with 1.2 microM CAI. Since these drugs are in phase I trials the synergistic action of quercetin and CAI may be of interest in clinical trials for breast carcinoma.

Aminoimidazole Carboxamide↗

PubMed1995

Regulation of signal transduction.

1. A systematic study is reported on the control of 1-phosphatidylinositol 4-kinase (PI kinase) and PI 4-phosphate 5-kinase (PIP kinase), enzymes of the phosphatidylinositol phosphorylation pathway which leads to the production of second messengers. IP3 and DAG. In liver of normal male, adult, fed Wistar rats the steady state activity of PI kinase was 0.5 +/- 0.01 and that of PIP kinase was 0.046 +/- 0.003 nmol/hr/mg protein. The concentration of IP3 was 1.8 +/- 0.1 pmol/mg protein. 2. That the two kinases have short half-lives was observed in starvation. where in the rat liver or bone marrow activities rapidly decreased and on refeeding were restored in a day. Injection to rats of the protein synthetic inhibitor, cycloheximide, yielded t1/2 = 80 min for the two enzymes in bone marrow and t1/2 = 80 min in liver. 3. Linkage of the signal transduction enzymes with proliferation was shown by the high activities as compared to liver of these enzymes in rat organs of high cell renewal capacity, e.g., thymus, bone marrow, spleen and testes. 4. Linkage with malignant proliferation was indicated by the observation that in rat hepatomas the enzyme activities increased 5- to 9-fold and were highest in rapidly growing hepatoma 3924A (29- and 45-fold). 5. In human primary ovarian carcinoma PI and PIP kinase activities were elevated 4.4 and 2.9-fold, respectively, and in OVCAR-5 cells, 32- and 11-fold, respectively. Similar increases were observed in MDA-MB-435 human breast carcinoma cells in comparison with normal breast parenchymal cells. 6. The linkage of signal transduction enzyme activities with malignant proliferation was also observed in experiments when human breast carcinoma cells were plated in flasks and expressed their proliferative capacity in the log phase. PI and PIP kinase activities steadily and coordinately increased to a peak 11-fold rise in mid-log phase. In late log and plateau phases the kinase activities gradually declined to the starting level. Similar observations were made for the two enzymes in human ovarian carcinoma OVCAR-5 cells and in rat hepatoma 3924A cells in tissue culture. 7. In animals injected with cycloheximide the bone marrow PI and PIP kinase activities exhibited t1/2 = 0.12 hr, the shortest decay rate in comparison with 8 enzymes of purine and pyrimidine biosynthesis with t1/2 = 0.6 to 4.3 hr. 8. Injection of tiazofurin decreased PI and PIP kinase activities in the bone marrow with t1/2 = 82 and 78 min, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

1-Phosphatidylinositol 4-Kinase↗

PubMed1995

Volume scanning in the evaluation of fetal malformations: a new dimension in prenatal diagnosis.

Three-dimensional ultrasound examination was performed in 204 patients with a fetal malformation detected by conventional ultrasound. The patients were examined between 13 and 40 weeks of gestation. The ultrasound equipment used was a Combison 330 and a Combison 530 (Kretztechnik, Austria) with an abdominal Voluson sector transducer (3.5/5 MHz) (Kretztechnik, Austria). This ultrasound system can provide a high-quality three-dimensional surface or translucency image of fetal structures similar to that of a photograph or an X-ray image within seconds without an additional expensive work-station. Of the 204 patients examined with three-dimensional ultrasound, this technique proved advantageous in demonstrating fetal defects in 62% (127/204). In 36% (73/204), the three-dimensional technique gave the same information and in four fetuses with a cardiac malformation (2%), the three-dimensional technique was disadvantageous, due to movement artefacts during data acquisition. The technical advantages and problems of this three-dimensional technique are demonstrated.

Artifacts↗

PubMed1995

Assessment of myometrial infiltration and preoperative staging by transvaginal ultrasound in patients with endometrial carcinoma.

In recent years, the incidence of carcinoma of the endometrium has shown an upward trend, such that it is currently the most frequently encountered malignant tumor of the female genital tract. An accurate preoperative diagnosis of the extent and spread of such carcinomas is of crucial importance for the selection of a therapeutic approach appropriate to the stage and infiltration of each particular tumor. In a prospective study of 80 patients with a carcinoma of the endometrium, performed at the Department of Obstetrics and Gynecology of the University of Mainz, we compared the preoperative findings of transvaginal sonography with the postoperative histological results with respect to the following parameters: endometrial thickness, demarcation of the boundary of the endometrium, myometrial infiltration depth and staging. In all of these patients, sonography revealed a distinct increase in the thickness of the endometrium. In all cases, the structure of the endometrium was found to be heterogenous, with an irregular and poorly delineated boundary. Assessments of the depth of tumor infiltration and the tumor staging obtained by transvaginal sonography were found to correlate with the histological findings in 85% and 87.5% of the cases, respectively. Thus, in cases of endometrial carcinoma, transvaginal sonography has an essential role to play in devising an individualized operative treatment program that takes into account the extent, spread and stage of the tumor.

Adult↗

PubMed1995

[Orbital diameter, inner and outer orbital distance. A growth model of fetal orbital measurements].

AIM: Aim of this study was to establish a growth model for the intrauterine growth of the following fetal parameters: orbital diameter, interorbital and biocular diameters. METHOD: Data were measured in a prospective cross-sectional study with real-time ultrasound. The study group consisted of 1090 healthy fetuses between 12 and 41 weeks gestation. For curve standardisation a growth model for all parameters was used. RESULTS: Using this growth model growth profiles (5., 50., and 95. percentiles) were established. All orbital parameters showed a nonlinear growth. CONCLUSION: Since ocular and orbital malformations (anophthalmia, microphthalmia, hypo- and hypertelorism) are often principal signs of generalised syndromes, orbital biometry is helpful for a detailed prenatal investigation of the fetal face. This is demonstrated in 2 cases with an orbital malformation (orbital hypoplasia, hypotelorism).

Cephalometry↗

PubMed1995

[Normal ultrasound curves of the fetal osseous thorax and fetal lung].

Over and above the evaluation of fetal standard data, chest and lung measurements were performed in a prospective cross-sectional study with real-time ultrasound. The study group consisted of 610 patients between 12 and 41 weeks' gestation. Only uncomplicated pregnancies with carefully documented gestational age were included. Patients with multiple pregnancy, fetal anomalies, intrauterine growth retardation or macrosomia and patients with oligohydramnios were excluded. Transversal (BTTD) and sagittal (BTSD) diameter of the bony fetal thorax were measured as an outer-outer-measurement at the level of the atrioventricular valves; the thorax should be as circular as possible and at right angles to the fetal spine. Lung measurements (LD) were performed in the same plane in the direct extension of the long axis of the fetal heart. The circumference of the bony thorax (BTC) was calculated from the two thoracic diameters according to the formula BTC = (BTTD+BTSD)/2 x 3.142. For all parameters growth curves with 5., 50. and 95. percentiles were established. Growth of the bony thorax as well as the lung diameter was shown in a nonlinear function. Lung diameter and thoracic circumference were used to calculate the ratio of these two parameters with reference to the gestational age.

Anthropometry↗

PubMed1995

Genetic mapping of the multiple endocrine neoplasia type 1 locus at 11q13.

Oncogenesis of tumours related to multiple endocrine neoplasia type 1 (MEN1) is associated with somatic deletions involving the MEN1 locus at chromosomal region 11q13, suggesting inactivation of a tumour-suppressor gene in this region. Here we describe the localization of the MEN1 gene to a 900-kb region, based on linkage analysis in affected families and deletion mapping of MEN1-associated tumours. In addition, a set of microsatellite markers mapped to the 11q11-13 region were used for linkage analysis in a large Tasmanian MEN1 pedigree, demonstrating the usefulness of these markers for presymptomatic testing in affected families.

Adult↗

PubMed1995

Direct cardiac electrophysiologic effects of sufentanil and vecuronium in isolated guinea-pig hearts.

Sufentanil and vecuronium are commonly used simultaneously in anaesthesia. Bradycardia and asystole have been described immediately after the administration of these two compounds. Therefore, the purpose of the present study was to evaluate the direct cardiac effects of sufentanil and vecuronium in all parts of the cardiac pacemaker and conduction system. The electrophysiological effects of sufentanil and vecuronium were studied in isolated spontaneously beating guinea-pig hearts perfused by the method of Langendorff. At a concentration of 0.1 mumol/l sufentanil a significant reduction of the spontaneous sinus rate, prolongation of atrioventricular, intraventricular and His' bundle conduction could be observed. The highest concentration of 10 mumol/l of sufentanil led to an overall slowing of conduction velocity and to an profound showing of spontaneous sinus rate. AV nodal as well as atrial and ventricular refractoriness were markedly prolonged at this high concentration of sufentanil. In contrast, during perfusion with vecuronium at a concentration of 0.1 mumol/l up to 10 mumol/l no significant effects on cardiac conduction and pacemaker activity could be observed. In conclusion, the electrophysiological effects of sufentanil are comparable to that of unspecific calcium antagonists. Therefore, especially in patients with a preexisting damage of the cardiac conduction system, the indirect effect of the combination of sufentanil and vecuronium which is predominantly responsible for bradycardia and asystole may be worsened by the direct effects of sufentanil.

Animals↗