Urgent Endovascular Treatment for Non-traumatic Descending Thoracic Aortic Rupture

PURPOSE

To evaluate the efficacy of endovascular repair of non-traumatic rupture of the descending thoracic aorta.

MATERIALS AND METHODS

From January 2011 to August 2017, 22 consecutive patients (16 men, mean age 73.7 years, range 63-92 years) with non-traumatic rupture of the descending thoracic aorta were treated endovascularly. Thirty-day mortality as well as procedure-related morbidity including stroke, renal, pulmonary and spinal complications were retrospectively assessed. Median follow-up was 29 months (range 6-65 months).

RESULTS

Nine patients had type B dissections, and 13 had atherosclerotic aortic aneurysms. The technical success was 100%; 86.3% of patients (19/22) were treated percutaneously. Thirteen patients (59%) received a single endograft, 8 (36%) received 2 endografts, and 1 received 3 endografts. The endograft diameters ranged between 28 and 46 mm. Two dissection patients received additional distal bare metal true lumen stents. Eleven patients required additional drainage of thoracic hematoma. Three primary percutaneous sites (15.7%) required surgical revision. No spinal cord ischemic or renal complications were observed. Stroke was observed in 2 patients (9%), both with full coverage of left subclavian artery origin. Four patients (18%) required tracheostomy with prolonged respiratory support (range 10-15 days). The median intensive care unit stay was 5 days (range 1-27 days). The 30-day mortality was 18.1% (4/22).

CONCLUSION

Endoluminal repair of non-traumatic rupture of the descending thoracic aorta can be performed percutaneously. It showed a 30-day mortality of 18.1%, and no spinal cord injury or renal complications were observed in surviving patients at follow-up.

LEVEL OF EVIDENCE

Level 4, case series.

Prävalenz von Gastroschisis, Omphalozele, Spina bifida und orofazialen Spaltbildungen bei Neugeborenen im Zeitraum Januar 2000–Dezember 2010 in Leipzig, Sachsen, Sachsen-Anhalt und Deutschland

Hintergrund: Zahlreiche Studien beschreiben weltweit eine Zunahme angeborener Fehlbildungen. Diese sind in Deutschland die häufigste Todesursache im frühen Kindesalter. Die hier vorliegende Studie untersuchte lokale und nationale Trends der Prävalenz von Gastroschisis, Omphalozele, Spina bifida und orofazialen Spaltbildungen von 2000 bis 2010.

Methoden: Die Prävalenz der 4 Fehlbildungen wurde im Zeitraum Januar 2000–Dezember 2010 mithilfe von 4 Datenquellen aus Leipzig, Sachsen, Sachsen-Anhalt und Deutschland untersucht.

Ergebnisse: Die Prävalenz der Fehlbildungen betrug im Untersuchungszeitraum in Deutschland bzw. in Sachsen 1,97/2,12 (Gastroschisis), 1,63/1,48 (Omphalozele), 5,80/8,11 (orofaziale Spaltbildungen) und 2,92/2,50 (Spina bifida) je 10 000 Lebendgeborene. In Sachsen zeigte sich ein Trendanstieg, dessen Effektstärken jedoch sehr gering sind (OR/Jahr zwischen 1,01–1,09). Auch in Deutschland insgesamt wurde eine signifikante Zunahme der Fehlbildungen beobachtet (OR/Jahr zwischen 1,01–1,04), ausgenommen davon war die Lebendgeborenenprävalenz der Spina bifida, die abzunehmen schien (OR/Jahr 0,986 (0,97–1,0), p-korrigiert=0,04).

Schlussfolgerung: Ob ein tatsächlicher Anstieg der Prävalenzen besteht oder lediglich Artefakte einen Anstieg vortäuschen, ist unklar. Änderungen in der Erfassungs- und Verschlüsselungspraxis, Fehlcodierungen, Doppel- und/oder lückenhafte Erfassung der Fehlbildungen könnten die Daten verfälschen. Da nur in Sachsen-Anhalt und Rheinland-Pfalz das Auftreten von Fehlbildungen prospektiv erfasst wird, könnten im Übrigen auch nur in diesen Bundesländern zeitnah Veränderungen der Fehlbildungsprävalenz erkannt werden. Angesichts der anscheinenden oder scheinbaren Zunahme von Fehlbildungen und der offensichtlich fehlerhaften Datenlage ist ein bundesweites oder sind weitere regionale Register für eine bessere und zeitnahe Erkennung und Erfassung von Fehlbildungen in Deutschland notwendig.

Impact of genetic and nongenetic factors on interindividual variability in 4β-hydroxycholesterol concentration

PURPOSE

Individual variability in the endogenous CYP3A metabolite 4β-hydroxycholesterol (4βOHC) is substantial, but to which extent this is determined by genetic and nongenetic factors remains unclear. The aim of the study was to evaluate the explanatory power of candidate genetic variants and key nongenetic factors on individual variability in 4βOHC levels in a large naturalistic patient population.

METHODS

We measured 4βOHC concentration in serum samples from 655 patients and used multiple linear regression analysis to estimate the quantitative effects of CYP3A4*22, CYP3A5*3, and POR*28 variant alleles, comedication with CYP3A inducers, inhibitors and substrates, sex, and age on individual 4βOHC levels.

RESULTS

4βOHC concentration ranged >100-fold in the population, and the multiple linear regression model explained about one fourth of the variability (R ² = 0.23). Only comedication with inducers or inhibitors, sex, and POR genotype were significantly associated with individual variability in 4βOHC level. The estimated quantitative effects on 4βOHC levels were greatest for inducer comedication (+>313%, P < 0.001), inhibitor comedication (-34%, P = 0.021), and female sex (+30%, P < 0.001), while only a modestly elevated 4βOHC level was observed in carriers vs. noncarriers of POR*28 (+11%, P = 0.023).

CONCLUSIONS

These findings suggest that the CYP3A4*22, CYP3A5*3, and POR*28 variant alleles are of limited importance for overall individual variability in 4βOHC levels compared to nongenetic factors.

The p97-Ufd1-Npl4 ATPase complex ensures robustness of the G2/M checkpoint by facilitating CDC25A degradation

The p97-Ufd1-Npl4 ATPase complex is associated with the response to DNA damage and replication stress, but how its inactivation leads to manifestation of chromosome instability is unclear. Here, we show that p97-Ufd1-Npl4 has an additional direct role in the G2/M checkpoint. Upon DNA damage, p97-Ufd1-Npl4 binds CDC25A downstream of ubiquitination by the SCF-βTrCP ligase and facilitates its proteasomal degradation. Depletion of Ufd1-Npl4 leads to G2/M checkpoint failure due to persistent CDC25 activity and propagation of DNA damage into mitosis with deleterious effects on chromosome segregation. Thus, p97-Ufd1-Npl4 is an integral part of G2/M checkpoint signaling and thereby suppresses chromosome instability.

Development of an in vitro embryotoxicity test using murine embryonic stem cell cultures

Mouse embryonic stem (ES) cell line D3 was used to establish conditions for a reproducible differentiation of ES cells in culture. ES cells can be maintained in an undifferentiated state by cultivation on a feeder layer of embryonic fibroblasts. ES cells form aggregates in suspension and can spontaneously differentiate into complex organized embryoid bodies (EBs), which in many respects resemble early postimplantation mouse embryos. Under appropriate culture conditions various cell and tissue types will develop in EBs: these include myocardial and skeletal muscle, nerve cells, chondrocytes and blood cells. Retinoic acid (RA) was used as an embryotoxic substance to test the application of ES cell cultures in in vitro embryotoxicity testing. RA (1 x 10(-8)m) induced an increase in skeletal muscle cell differentiation, which followed a characteristic pattern: day 10 is characterized by the first appearance of mononucleated myoblasts; day 12 shows the fusion of myoblasts; on day 13, multinucleated myotubes can be detected, and on day 25 contractile myofibres are present in ES cell cultures. The development of blood islands with red cells enhanced by erythropoietin in EBs has encouraged the hope that, subsequently, more mature stages of erythroid, myeloid and lymphoid cell development could occur in vitro. These data provide further support for the use of ES cells in an in vitro assay for embryotoxicity testing.

Prevalidation of the Embryonic Stem Cell Test (EST)-A New In Vitro Embryotoxicity Test

Pluripotent embryonic stem cells (ES cells) of the mouse (cell-line D3) can be maintained in the undifferentiated state in the presence of LIF (Leukaemia Inhibitory Factor). Upon withdrawal of LIF, these cells differentiate into various cell types under appropriate conditions. This property of ES cells allowed us to develop an in vitro embryotoxicity test, the Embryonic Stem Cell Test (EST; In Vitro Toxicology 1997, 10, 119-127), which does not require taking embryonic cells or tissues from pregnant animals. In the EST, the effect of test chemicals on three endpoints is assessed: inhibition of the differentiation of ES cells into contracting myocard, cytotoxicity in ES cells and cytotoxicity in mouse 3T3 fibroblasts, which are serving as differentiated cells in the test. The results of a prevalidation study of the EST are described, which was conducted according to the ECVAM prevalidation scheme. In the first stage of the study (Phase I), a standard operating procedure (SOP) was elaborated. In the second phase (Phase II), the interlaboratory transferability of the EST was assessed using three test chemicals representing three classes of embryotoxicity (a strong, a weak and a non-embryotoxic chemical) in two European laboratories (ZEBET at the BgVV in Berlin, Germany; ECVAM at the JRC in Ispra, Italy) and one US laboratory (Institute for In Vitro Sciences (IIVS) in Gaithersburgh, MA, USA). In the final stage of prevalidation (Phase III), nine test chemicals and a positive control were tested under blind conditions at ZEBET and ECVAM. The statistical evaluation of the results led to the development of an improved prediction model for the EST.

A comparison of Dutch frail older adults in 1998 and 2008: prevalences and determinants

Background

Objectives

Methods

Results

Conclusions

Endolysosomal sorting of ubiquitylated caveolin-1 is regulated by VCP and UBXD1 and impaired by VCP disease mutations

The AAA-ATPase VCP (also known as p97) cooperates with distinct cofactors to process ubiquitylated proteins in different cellular pathways. VCP missense mutations cause a systemic degenerative disease in humans, but the molecular pathogenesis is unclear. We used an unbiased mass spectrometry approach and identified a VCP complex with the UBXD1 cofactor, which binds to the plasma membrane protein caveolin-1 (CAV1) and whose formation is specifically disrupted by disease-associated mutations. We show that VCP-UBXD1 targets mono-ubiquitylated CAV1 in SDS-resistant high-molecular-weight complexes on endosomes, which are en route to degradation in endolysosomes. Expression of VCP mutant proteins, chemical inhibition of VCP, or siRNA-mediated depletion of UBXD1 leads to a block of CAV1 transport at the limiting membrane of enlarged endosomes in cultured cells. In patient muscle, muscle-specific caveolin-3 accumulates in sarcoplasmic pools and specifically delocalizes from the sarcolemma. These results extend the cellular functions of VCP to mediating sorting of ubiquitylated cargo in the endocytic pathway and indicate that impaired trafficking of caveolin may contribute to pathogenesis in individuals with VCP mutations.

Cdc48/p97-Ufd1-Npl4 antagonizes Aurora B during chromosome segregation in HeLa cells

During exit from mitosis in Xenopus laevis egg extracts, the AAA+ ATPase Cdc48/p97 (also known as VCP in vertebrates) and its adapter Ufd1-Npl4 remove the kinase Aurora B from chromatin to allow nucleus formation. Here, we show that in HeLa cells Ufd1-Npl4 already antagonizes Aurora B on chromosomes during earlier mitotic stages and that this is crucial for proper chromosome segregation. Depletion of Ufd1-Npl4 by small interfering RNA (siRNA) caused chromosome alignment and anaphase defects resulting in missegregated chromosomes and multi-lobed nuclei. Ufd1-Npl4 depletion also led to increased levels of Aurora B on prometaphase and metaphase chromosomes. This increase was associated with higher Aurora B activity, as evidenced by the partial resistance of CENP-A phosphorylation to the Aurora B inhibitor hesperadin. Furthermore, low concentrations of hesperadin partially rescued chromosome alignment in Ufd1-depleted cells, whereas, conversely, Ufd1-depletion partially restored congression in the presence of hesperadin. These data establish Cdc48/p97-Ufd1-Npl4 as a crucial negative regulator of Aurora B early in mitosis of human somatic cells and suggest that the activity of Aurora B on chromosomes needs to be restrained to ensure faithful chromosome segregation.

Cdc48/p97 and Shp1/p47 regulate autophagosome biogenesis in concert with ubiquitin-like Atg8

The molecular details of the biogenesis of double-membraned autophagosomes are poorly understood. We identify the Saccharomyces cerevisiae AAA-adenosine triphosphatase Cdc48 and its substrate-recruiting cofactor Shp1/Ubx1 as novel components needed for autophagosome biogenesis. In mammals, the Cdc48 homologue p97/VCP and the Shp1 homologue p47 mediate Golgi reassembly by extracting an unknown monoubiquitinated fusion regulator from a complex. We find no requirement of ubiquitination or the proteasome system for autophagosome biogenesis but detect interaction of Shp1 with the ubiquitin-fold autophagy protein Atg8. Atg8 coupled to phosphatidylethanolamine (PE) is crucial for autophagosome elongation and, in vitro, mediates tethering and hemifusion. Interaction with Shp1 requires an FK motif within the N-terminal non-ubiquitin-like Atg8 domain. Based on our data, we speculate that autophagosome formation, in contrast to Golgi reassembly, requires a complex in which Atg8 functionally substitutes ubiquitin. This, for the first time, would give a rationale for use of the ubiquitin-like Atg8 during macroautophagy and would explain why Atg8-PE delipidation is necessary for efficient macroautophagy.

IMP dehydrogenase basal activity in MOLT-4 human leukaemia cells is altered by mycophenolic acid and 6-thioguanosine

OBJECTIVE

Depletion of guanine and deoxyguanine nucleotides by inhibition of inosine 5'-monophosphate dehydrogenase (IMPDH, EC 1.1.1.205) or introduction of 6-thioguanine nucleotide antimetabolites are two principles of retarding cell proliferation by interference with the cellular purine nucleotide pool. IMPDH activity may be a promising pharmacodynamic biomarker during immunosuppressive and anticancer pharmacotherapy. The aim of the study was to investigate the impact of mycophenolic acid (MPA) and 6-thioguanosine (tGuO) on IMPDH basal activity.

MATERIAL AND METHODS

We studied the IMPDH basal activity (i.e. the enzyme activity following inhibitor exposure, but measured in absence of the inhibitor) in response to increasing concentrations of the IMPDH inhibitor MPA and the antimetabolite tGuO in MOLT-4 human leukaemia cells. In parallel, IMPDH gene expression and cellular purine nucleotide concentrations were examined.

RESULTS

A biphasic concentration-dependent influence of MPA on the IMPDH basal activity was observed. At concentrations < or =IC50, MPA increased the IMPDH basal activity. The increase was associated with elevated expression of IMPDH2. Despite increased expression, the basal enzyme activity decreased following exposure to high MPA concentrations. The IMPDH2 expression increased modestly in response to tGuO exposure. However, the IMPDH basal activity decreased when the cells were exposed to a proliferation-blocking tGuO concentration.

CONCLUSIONS

These findings demonstrate that IMPDH basal activity is influenced by MPA and tGuO, and suggest that reduced IMPDH basal activity is related to the proliferation-blocking effects of these agents.

Piecemeal microautophagy of the nucleus requires the core macroautophagy genes

Autophagy is a diverse family of processes that transport cytoplasm and organelles into the lysosome/vacuole lumen for degradation. During macroautophagy cargo is packaged in autophagosomes that fuse with the lysosome/vacuole. During microautophagy cargo is directly engulfed by the lysosome/vacuole membrane. Piecemeal microautophagy of the nucleus (PMN) occurs in Saccharomyces cerevisiae at nucleus-vacuole (NV) junctions and results in the pinching-off and release into the vacuole of nonessential portions of the nucleus. Previous studies concluded macroautophagy ATG genes are not absolutely required for PMN. Here we report using two biochemical assays that PMN is efficiently inhibited in atg mutant cells: PMN blebs are produced, but vesicles are rarely released into the vacuole lumen. Electron microscopy of arrested PMN structures in atg7, atg8, and atg9 mutant cells suggests that NV-junction-associated micronuclei may normally be released from the nucleus before their complete enclosure by the vacuole membrane. In this regard PMN is similar to the microautophagy of peroxisomes (micropexophagy), where the side of the peroxisome opposite the engulfing vacuole is capped by a structure called the "micropexophagy-specific membrane apparatus" (MIPA). The MIPA contains Atg proteins and facilitates terminal enclosure and fusion steps. PMN does not require the complete vacuole homotypic fusion genes. We conclude that a spectrum of ATG genes is required for the terminal vacuole enclosure and fusion stages of PMN.

The development of new concepts for assessing reproductive toxicity applicable to large scale toxicological programmes

Large scale toxicological testing programmes which are currently ongoing such as the new European chemical legislation REACH require the development of new integrated testing strategies rather than applying traditional testing schemes to thousands of chemicals. The current practice of requiring in vivo testing for every possible adverse effect endanger the success of these programmes due (i) to limited testing facilities and sufficient capacity of scientific/technical knowledge for reproductive toxicity; (ii) an unacceptable number of laboratory animals involved (iii) an intolerable number of chemicals classified as false positive. A key aspect of the implementation of new testing strategies is the determination of prevalence of reproductive toxicity in the universe of industrial chemicals. Prevalences are relevant in order to be aware on the expected rate of false classification during the toxicological testing and to implement appropriate measures for their avoidance. Furthermore, a detailed understanding on the subendpoints affected by reproductive toxicants and the underlying mechanisms will lead to more science based testing strategies integrating alternative methods without compromising the protection of consumers.

The effects of solvents on embryonic stem cell differentiation

Dimethyl sulfoxide (DMSO) and ethanol are common organic solvents used for dissolving lipophilic substances for in vitro testing. However, DMSO is known to induce differentiation in embryonic stem (ES) and embryonic teratocarcinoma (EC) cells. In order to clarify if solvents like DMSO and ethanol have an influence on in vitro developmental toxicity test systems, the presented study has evaluated their effects on differentiation by using different test systems. ES and EC cells were transfected with a construct containing the mTert promoter combined with the green fluorescent protein gene (GFP). A down-regulation of mTert, a marker for undifferentiated cells, results in a lower expression of GFP, which could be measured by flow cytometry. Taking the specific characteristics of ES and EC cells into account this effect could be a hint for the interaction of DMSO with embryonic development. Additionally, the effects of the solvents ethanol and DMSO on Oct-4 expression, another marker for undifferentiated cells, were measured in wild-type ES cells. Both selected molecular markers demonstrated an induction of differentiation after exposure to DMSO; in wild-type ES cells at a concentration of 0.125% and in transgenic EC cells at a concentration of 0.25% DMSO. All other differences from controls, including those which attained a level of statistical significance, were minor or not dosage related in degree, or were not consistent over time and are, therefore, considered to be of little toxicological importance. In addition, a cytotoxicity test demonstrated that the solvents affected the employed molecular markers in non-cytotoxic concentrations. The ES cells were the most sensitive towards the cytotoxic effects of the solvent DMSO while the EC cells were more sensitive when treated with the solvent ethanol.

In vivo metabolism of LDL subfractions in patients with heterozygous FH on statin therapy

LDL can be subfractionated into buoyant (1.020-1.029 g/ml(-1)), intermediate (1.030-1.040 g/ml(-1)), and dense (1.041-1.066 g/ml(-1)) LDLs. We studied the rebound of these LDL-subfractions after LDL apheresis in seven patients with heterozygous familial hypercholesterolemia (FH) regularly treated by apheresis (58 +/- 9 years, LDL-cholesterol = 342 +/- 87 mg/dl(-1), triglycerides = 109 +/- 39 mg/dl(-1)) and high-dose statins. Apolipoprotein B (apoB) concentrations were measured in LDL subfractions immediately after and on days 1, 2, 3, 5, and 7 after apheresis. Compartmental models were developed to test three hypotheses: 1) that dense LDLs are derived from the delipidation of buoyant and intermediate LDLs (model A); 2) that dense LDLs are generated directly from LDL-precursors (model B); or 3) that a model combining both pathways (model C) is necessary to describe the metabolism of dense LDLs. In all models, it was assumed that apoB production and fractional catabolic rate (FCR) did not change with apheresis. Apheresis decreased buoyant, intermediate, and dense LDL-apoB by 60 +/- 12%, 67 +/- 5%, and 69 +/- 11%, respectively. Models B and C, but not model A, described the rebound data. The model with the greatest biological plausibility (model C) was used to estimate metabolic parameters. FCR was 1.05 +/- 0.86 d(-1), 0.48 +/- 0.11 d(-1), and 0.69 +/- 0.24 d(-1) for buoyant, intermediate, and dense LDLs, respectively. Dense LDL production was 17.3 +/- 0.2 mg/kg(-1)/d(-1), 58% of which was derived directly from LDL precursors (VLDL, IDL, or direct secretion), while 42% was derived from buoyant and intermediate LDLs. Thus, our data indicate that in statin-treated patients with heterozygous FH dense LDLs originate from two sources. Whether this is also valid in other metabolic situations (with predominant small, dense LDLs) remains to be determined.

The Use of Embryonic Stem Cells for Regulatory Developmental Toxicity Testing In Vitro - The Current Status of Test Development

The future chemical policy of the European Union as well as the 7th amendment of the cosmetic directive is calling for the development of alternative tests to animal experimentation for toxicological safety testing. In the field of embryotoxicity one of the most promising in vitro models are based on embryonic stem cells. The embryonic stem cell test has already been validated in comparison to in vivo results in an international blind collaboration study. The presented review is discussing the use, limitations and further needs for the test in order to be fully suitable for regulatory acceptance. In this context, it is summarized which requirements for an in vitro embryotoxicity test have to be fulfilled for regulatory toxicity testing. In addition, an overview about the current status of test development of other embryonic stem cell tests is presented. Several workshops have reviewed the progress of in vitro tests for developmental toxicity testing. A general consensus of these workshops has been that one single test will not be sufficient to cover all manifestations of developmental toxicity. The establishment of a test battery for developmental toxicity is required. This will be even more challenging since the principles of a composing test strategy and its validation have not been defined yet. Finally, the unique possibility of combining the human embryonic stem cell technology and the microarray techniques might lead to a deeper understanding of the toxicological mechanisms of human developmental toxicants.

Monitoring of teratogenic effects in vitro by analysing a selected gene expression pattern

The development of in vitro methods for regulatory embryotoxicity testing is challenging since the understanding of chemical effects on the mammalian development is still poor. The aim of the project is to identify marker genes during in vitro cell differentiation of murine embryonic stem cells, in order to predict chemical effects on cell differentiation of specific target tissues. The present study is focusing on the expression pattern by using semi-quantitative reverse transcriptase (RT)-PCR of key genes involved in cardiomyocytes development; i.e. Oct-4, Brachyury, Nkx2.5 and alpha myosin heavy chain (alpha-MHC). Two reference chemicals with well-known in vivo data have been analysed by using this approach: retinoic acid and lithium chloride. Retinoic acid has been selected as a teratogen affecting several target tissues, whereas lithium chloride has been described to affect the development of the cardiovascular system. We demonstrate that retinoic acid already affects in the early stage of germ layer formation, which was demonstrated by a change of Oct-4 and Brachyury gene expression. As we expected, the expression of cardiac specific genes (Nkx2.5, alpha-MHC) has been also modified. In contrary, the Oct-4 and Brachyury expression was not changed by lithium treatment. In this case, we observed a modification in the normal gene expression pattern, for alpha-MHC and Nkx2.5, demonstrating that lithium chloride affects the later stage of heart development. These data suggest that the inclusion of selective target organ genes in an established embryotoxicity test allows to predict effects of chemicals and drugs to the heart development.

[Drugs and street traffic. Playing it safe for yourself and your patient]

Participation in road traffic/driving a motorized vehicle involves numerous skills capable of being influenced by medications. Common examples of the latter are psychoactive drugs, hypnotics and sedatives, antihistaminics, analgesics and psychostimulants. Both the therapeutic effect itself and potential side effects can pose a danger, for example, via the loss of psychomotoric coordination, or equilibrium or sensory disturbances. Every fourth accident can be traced back to the influence of some medication or other. In addition, the patient himself may be harboring a variety of major risks including age, physiological and mental status and previous illnesses.

The use of quantitative image analysis in the assessment of in vitro embryotoxicity endpoints based on a novel embryonic stem cell clone with endoderm-related GFP expression

The capacity of pluripotent embryonic stem cells (ESC) to differentiate in vitro into various tissues provides the opportunity to develop an in vitro assay for investigating mechanisms of developmental toxicity. ESC clones carrying tissue specific reporter gene constructs are currently being developed. The clones should allow the quantification of the effects of chemicals on the development of germ layers and main target tissues. We report the establishment of the alpha-fetoprotein_GFP/D3 reporter gene clone: alpha-fetoprotein (AFP) enhancers and the homologous promoter regulate green fluorescent protein (GFP) expression in cells of the D3-ESC clone. AFP was used as a marker for endodermal cells. Differentiation of this clone via embryoid bodies (EBs, spheroids of cells) leads to green fluorescence on the surfaces of EBs. AFP- related GFP expression was confirmed. An easy and quick image analysis-based endpoint measurement was developed for quantifying low amounts of cells expressing GFP. As demonstrated with the embryotoxic chemical diphenylhydantoin, image analysis can be used to distinguish between a general effect on EB growth and a specific effect on the development of GFP-positive endodermal cells. Endoderm development was inhibited at a different dose than cardiomyocyte development.

Re-defining the chromatin loop domain

It is commonly accepted that the loop domain represents the basic structural unit of eukaryotic chromatin associated with DNA replication, gene expression and higher order packaging. However, molecular-cytological information defining the loop domain is lacking. There are gaps in our knowledge of the loop structure and how it regulates gene expression. The combination of new data/reagents from the Human Genome Project plus the use of novel molecular cytological technology will provide answers. Here we briefly review the status of chromatin loop research and pose questions that need to be addressed. New experimental systems are also presented to target some long-standing issues regarding the structure and function of the chromatin loop domain and its relationship with the nuclear matrix. This new knowledge will have a profound impact for modern genetics and molecular medicine.

Establishment of an in vitro reporter gene assay for developmental cardiac toxicity

This study is based on the unique potential of pluripotent embryonic stem (ES) cells to differentiate in vitro into embryoid bodies containing cell lineages representative of most cell types found in the mammalian fetus. However, the use of wild type ES cells as an in vitro assay for embryotoxicological studies is complicated by the simultaneous development of various cellular phenotypes. This prevents a quantitative assessment of drug effects on one specific cell type. Here we report the effects of 15 chemicals on cardiac differentiation as determined by various specific toxicological endpoints such as morphological inspection (contractile activity), quantitative mRNA analysis and cardiac-specific expression of green fluorescent protein (GFP), used as a quantitative reporter. The data from the different endpoints have been subjected to a statistical analysis, and a preliminary prediction model is proposed. The results demonstrate that genetically-engineered ES cells could provide a valuable tool for estimating the developmental cardiotoxic potential of compounds in vitro and form the basis for automated analysis in a high-throughput system.

Spectral karyotyping (SKY) of mouse meiotic chromosomes

The spectral karyotyping procedure of in situ hybridization with chromosome-specific probes assigns a unique colour code to each of the 21 mouse mitotic chromosomes. We have adapted this procedure to meiotic prophase chromosomes, and the results show that each of the pachytene or metaphase I bivalents can be identified. This technique has the potential to recognize synaptic anomalies and chromosome-specific structural and behavioural characteristics. We confirm these potentials by the recognition of the heterologous synapsis of the X and Y chromosomes and by the variances of synaptonemal complex lengths for each of the colour-coded bivalents in eight prophase nuclei.

Spectral karyotyping of mouse cell line WMP2

We have evaluated the mouse cell line WMP2 using both GTG-banding analysis and spectral karyotyping to verify the reliability of using this established cell line derived from WMP/WMP mice. The WMP cell lines contain easily identifiable metacentric fusion chromosomes and are used extensively for gene mapping. Because of karyotypical changes in the WMP1 cell line, WMP2 was examined. Our results demonstrate that WMP2 is stable during culture, and the karyotype is simple and easy to use. Based on the findings discussed in this paper, we recommend the use of the WMP2 cell line for future prospective gene mapping in the mouse.

In vitro germ cell models for the detection of fertility impairment

Pluripotent embryonic carcinoma cells and pluripotent embryonic stem cells established from undifferentiated cells of an early mouse embryo were investigated for induction of proliferation inhibition, sister chromatid exchanges (SCE) and single-strand breaks by treatment with various germ cell mutagens. The comparison of malignant cells with nonmalignant cells showed an increased sensitivity of nonmalignant cells independent of their state of differentiation. Mitomycin C (MMC) inhibited the proliferation of nonmalignant cells at a concentration of 10(-6) M but did not affect growth of the teratocarcinoma cell line P19. There were no differences between the investigated cell lines at a lower MMC concentration. At the concentration of 10(-6) M MMC the sister chromatid exchanges of P19 were enhanced up to 41 SCE per metaphase. Testing of another germ cell mutagen, ethylnitrosourea (ENU), gave similar results: a decreasing generation time of nonmalignant cell lines after treatment with 1 mM ENU and no effect on the teratocarcinoma cells. This concentration also induced a high number of SCE. Single-strand breaks could be produced by exposure to methanmethylsulphonate (MMS). 56.3% of embryonic stem cell DNA was passing through the filter after MMS treatment. In contrast to the embryonic stem cells, only 35.6% of teratocarcinoma DNA was affected.

Development of prediction models for three in vitro embryotoxicity tests in an ECVAM validation study

Since 1997 the National Center for Documentation and Evaluation of Alternative Methods to Animal Experiments, ZEBET, in Berlin, has been coordinating a validation study aimed at prevalidation and validation of three in vitro embryotoxicity tests, funded by the European Center for the Validation of Alternative Methods (ECVAM) at the Joint Research Center (JRC, Ispra, Italy). The tests use the cultivation of postimplantation rat whole embryos (WEC test), cultures of primary limb bud cells of rat embryos (micromass or, MM, test), and cultures of a pluripotent mouse embryonic stem cell line (embryonic stem cell test or EST). Each of the tests was performed in four laboratories under blind conditions. In the preliminary phase of the validation study 6 out of 20 test chemicals comprising different embryotoxic potential (non, weakly, and strongly embryotoxic) were tested. The results were used to define biostatistically based prediction models (PMs) to identify the embryotoxic potential of test chemicals for the WEC test and the MM test. The PMs developed with the results of the preliminary phase of the validation study (training set) will be evaluated with the results of the remaining 14 test chemicals (definitive phase) by the end of the study. In addition, the existing, improved PM (iPM) for the EST, which had been defined previously, was evaluated using the results of the preliminary phase of this study. Applying the iPM of the EST to the results of this study, in 79% of the experiments, chemicals were classified correctly according to the embryotoxic potential defined by in vivo testing. For the MM and the WEC test, the PMs developed during the preliminary phase of this validation study provided 81% (MM test) and 72% (WEC test) correct classifications. Because the PM of the WEC test took into account only parameters of growth and development, but not cytotoxicity data, a second PM (PM2) was developed for the WEC test by incorporating cytotoxicity data of the differentiated mouse fibroblast cell line 3T3, which was derived from the EST. This approach, which has previously never been used, resulted in an increase to 84% correct classifications in the WEC test.

Pluripotent stem cells of the mouse as a potential in vitro model for mammalian germ cells. Sister chromatid exchanges induced by MMC and ENU in undifferentiated cell lines compared to differentiated cell lines

We tried to develop an in-vitro test system which could serve as a model for mammalian germ cells in vivo. Two pluripotent cell types were used, because they express some germ cell specific immunological and biochemical markers: (1) Embryonal carcinoma cells (ECC) of the line P19 had been isolated from a teratocarcinoma of murine primordial germ cells (PGC). (2) Embryonal stem cells (ESC) are obtained from the inner cell mass of mouse blastocysts. Sister chromatid exchanges (SCE) induced by mitomycin C and ethylnitrosourea (ENU) were analysed in the two undifferentiated cell lines, ECC and ESC, to detect differences in their sensitivity compared with differentiated cell lines of the mouse. Neither of the model cell lines have shown a greater sensibility after exposure to MMC and ENU. In contrary, the carcinoma cell line was able to tolerate higher concentrations of these genotoxicants. Therefore, SCE analysis in the ECC and ESC lines used does not provide a suitable model for genotoxicity testing on mammalian germ cells.

Selective targeting of human lymphokine-activated killer cells by CD3 monoclonal antibody against the interferon-inducible high-affinity Fc gamma RI receptor (CD64) on autologous acute myeloid leukemic blast cells

The potential of the CD3 monoclonal antibody (MoAb) OKT3 to selectively target lymphokine-activated killer (LAK) cells and T-cell clones in vitro against autologous tumor cells was studied using material from patients with acute leukemias (19 acute myeloid leukemias [AML], and 3 acute lymphoblastic leukemias [ALL]). Cytotoxicity mediated by patient LAK cells against AML blasts, but not against ALL cells and autologous Epstein-Barr virus-transformed B cells, was enhanced 1.5-fold to 9.3-fold by OKT3 in all AML patients studied. The following findings suggest that the major target molecule on AML cells for OKT3-coated LAK cells is the high-affinity Fc receptor for IgG (Fc gamma RI; CD64): (1) susceptibility to killing by OKT3-coated effector LAK cells segregated with target cell expression of CD64; (2) preincubation of AML blasts with monomeric OKT3 (murine IgG2a), the Fc portion of which is known to have preferential binding affinity to CD64, resulted in lysis by autologous T cells that were not spontaneously cytotoxic; (3) OKT3-dependent increase in lysis of primary and relapsed AML cells by autologous T-cell clones correlated with the amount of target cell expression of CD64; (4) anti-leukemic cytotoxicity of OKT3-coated T cells could partially be inhibited by monomeric human Ig, the natural ligand of CD64; and (5) expression of CD64 (Fc gamma RI) on fresh AML cells could be increased by interferon-gamma (IFN-gamma) and IFN-alpha translating into further enhancement of lysis by autologous OKT3-coated LAK cells. Nonmalignant CD34+ cells sorted from peripheral blood were found to lack expression of CD64 and hence were not affected by OKT3-triggered T-cell targeting, as detected by colony formation assays. In conclusion, the in vitro data presented provide a rationale for the combined clinical use of recombinant interleukin-2, IFN-gamma, and low doses of CD3 MoAb to eliminate AML cells while sparing nonmalignant hematopoietic progenitor cells, for example, in the setting of purging procedures for autologous bone marrow transplantation.

Quantitative expression patterns of multidrug-resistance P-glycoprotein (MDR1) and differentially spliced cystic-fibrosis transmembrane-conductance regulator mRNA transcripts in human epithelia

P-glycoprotein (MDR1), that confers multidrug resistance in cancer, and the cystic-fibrosis transmembrane-conductance regulator (CFTR), that is causative defective in cystic fibrosis, belong to the family of ATP-binding transport proteins. The expression of MDR1 and CFTR in human epithelial tissues and the cell lines T84 and HT29 was estimated by primer-directed reverse transcription (RT) and subsequent monitoring of the kinetics of cDNA product formation during the polymerase chain reaction (PCR). MDR1 mRNA was found in high levels, 15-50 amol mRNA/microgram RNA, in the intestine, kidney, liver and placenta, and in low levels, 0.2 amol/microgram RNA, in respiratory epithelium. Large amounts of CFTR mRNA were measured in the gastrointestinal tract, whereas the kidney, as the phenotypically normal organ, and the lung, as the most severely affected organ in cystic fibrosis, both contained low amounts, 3 amol CFTR/microgram RNA. CFTR transcript levels of 1-5 amol/microgram RNA were determined in lymphocytes and lymphoblast cell lines, suggesting that lymphoblasts are an accessible source for the study of the molecular pathogenesis of cystic fibrosis. When transcripts were scanned by overlapping RT/PCR analyses, only transcript of expected size was detected for MDR1 mRNA, where variable in-frame deletions of either exon 4, 9 or 12 were observed in CFTR mRNA. The complete loss of single exons was seen at proportions of 1-40% in all investigated tissues and cell lines with large donor-to-donor variation. Exons 9 and 12 of the CFTR gene encode parts of the evolutionarily well-conserved first nucleotide-binding fold including the two Walker motifs. Alternative splicing may give rise to various CFTR forms of different function and localization.

Sodium dependence of the epithelial sodium conductance expressed in Xenopus laevis oocytes

The epithelial Na+ conductance was expressed in Xenopus laevis oocytes by injection of size-fractionated mRNA of bovine tracheal epithelium. Fractionation was achieved by sucrose density gradient centrifugation. Successful expression was analysed by recording current/voltage (I/V) curves in the presence and absence of amiloride (10 mumol/l). The newly expressed conductance was half-maximally inhibited by 44 nmol/l amiloride and exhibited a selectivity for Na+ over K+ of 140:1. I/V curves obtained at different extracellular Na+ concentrations ([Na+]o) were subjected to a Goldman-fit analysis to obtain the relation between Na+ permeability (PNa) and [Na+]o. The data show that decreasing [Na+]o from 85 mmol/l to 0.85 mmol/l increased PNa by more than threefold, which is thought to reflect Na+ channel inhibition by increasing [Na+]o. This effect clearly exceeded what can be attributed to concentration saturation of single Na+ channel conductance (Palmer and Frindt (1986) Proc Natl Acad Sci USA 83:2767). No correlation of inhibition with intracellular Na+ concentration was observed. Preservation of the [Na+]o-dependent self-inhibition by the newly expressed Na+ conductance suggests that it is an intrinsic property of the Na+ channel protein, probably mediated by an extracellular Na+ binding site.

Distribution patterns of the delta F508 mutation in the CFTR gene of CF-linked marker haplotypes in the German population

We have measured the frequency of the delta F508 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and its association with cystic fibrosis (CF)-linked marker haplotypes in the German population. Based on the analysis of 400 CF chromosomes, the frequency of the delta F508 mutation is estimated to be 77.3%, the vast majority being associated with marker haplotype KM19-XV2c 2 1. Our data further suggest the presence of another frequent CF mutation associated with this marker haplotype.

Frequency of the F508 deletion in the CFTR gene in Turkish cystic fibrosis patients

The F508 deletion in the cystic fibrosis transmembrane conductance regulator (CFTR) gene was found in 8 out of 30 Turkish cystic fibrosis (CF) chromosomes (27%). Five Turkish delta F508 CF chromosomes were associated with the risk haplotype B in KM19 (2 allele)/XV2c (1 allele). In the Turkish population, cystic fibrosis is predominantly caused by mutations other than the F508 deletion.

Selective expression of an amiloride-inhibitable Na+ conductance from mRNA of respiratory epithelium in Xenopus laevis oocytes

Poly(A)+RNA was prepared from primary cultures of human nasal polyp epithelia and from native bovine tracheal epithelia. Six to fifty nanograms mRNA were injected into prophase-arrested immature Xenopus laevis oocytes. One to four days later the oocytes were probed with electrophysiological techniques for induction of novel ion conductances. Oocytes injected with mRNA had lower membrane potentials (Vm) and resistances (Rm) than controls. By use of step changes in extracellular Na+ concentration and applying amiloride, a Na+ conductance could be identified in mRNA-injected oocytes, which was inhibited by submicromolar concentrations of amiloride with the same kinetics (Ki = 1.3 X 10(-7) mol/l) as in the original tissue. After complete inhibition of this conductance by 10(-5) mol/l amiloride, Vm and Rm approached the respective values of controls. The data indicate that oocytes express functional epithelial Na+ channels but apparently no other epithelial ion conductances from injected mRNA of respiratory epithelium.