Rapid detection of radiation-induced chromosomal aberrations in lymphocytes and hematopoietic progenitor cells by mFISH

Structural chromosome aberrations (SCAs) are sensitive indicators of a preceding exposure of the hematopoietic system to ionizing radiation. Cytogenetic investigations have therefore become routine tools for an assessment of absorbed radiation doses and their biological effects after occupational exposure or radiation accidents. Due to its speed and ease of use, fluorescence in situ hybridization (FISH) with whole chromosome painting (WCP) probes has become a method of choice to visualize SCAs. Until recently, this technique was limited to a rather small number of chromosomes, which could be tested simultaneously. As a result, only a fraction of the structural aberrations present in a sample could be detected and the overall dose effect had to be calculated by extrapolation. The recent introduction of two genome-wide screening techniques in tumor research, i.e., Spectral Karyotyping (SKY) and multicolor FISH (mFISH) now allows the detection of translocations involving any two non-homologous chromosomes. The present study was prompted by our desire to bring the power of mFISH to bear for the rapid identification of radiation-induced SCAs. We chose two model systems to investigate the utility of mFISH: lymphocytes that were exposed in vitro to 3 Gy photons and single hematopoietic progenitor cell colonies isolated from a Chernobyl victim 9 years after in vivo exposure to 5.4 Sv.In lymphocytes, we found up to 15 different chromosomes involved in rearrangements indicating complex radiation effects. Stable aberrations detected in hematopoietic cell colonies, on the other hand, showed involvement of up to three different chromosomes. These results demonstrated that mFISH is a rapid and powerful approach to detect and characterize radiation-induced SCAs in the hemopoietic system. The application of mFISH is expected to result in a more detailed and, thus, more informative picture of radiation effects. Eventually, this technique will allow researchers to rapidly delineate chromosomal breakpoints and facilitate the identification of the genes involved in radiation tumorigenesis.

Unusual 5' transcript complexity of plectin isoforms: novel tissue-specific exons modulate actin binding activity

Plectin, the most versatile cytolinker identified to date, has essential functions in maintaining the mechanical integrity of skin, skeletal muscle and heart, as indicated by analyses of plectin-deficient mice and humans. Expression of plectin in a vast variety of tissues and cell types, combined with a large number of different binding partners identified at the molecular level, calls for complex mechanisms regulating gene transcription and expression of the protein. To investigate these mechanisms, we analyzed the transcript diversity and genomic organization of the murine plectin gene and found a remarkable complexity of its 5'-end structure. An unusually high number of 14 alternatively spliced exons, 11 of them directly splicing into plectin exon 2, were identified. Analysis of their tissue distribution revealed that expression of a few of them is restricted to tissues such as brain, or skeletal muscle and heart. In addition, we found two short exons tissue-specifically spliced into a highly conserved set of exons encoding the N-terminal actin binding domain (ABD), common to plectin and the superfamily of spectrin/dystrophin-type actin binding proteins. Using recombinant proteins we show that a novel ABD version contained in the muscle-specific isoform of plectin exhibits significantly higher actin binding activity than other splice forms. This fine tuning mechanism based on alternative splicing is likely to optimize the proposed biological role of plectin as a cytolinker opposing intense mechanical forces in tissues like striated muscle.

On the Reversible Conjugation of

After administering [17-D(2)]GA(20) to Phaseolus coccineus L. cv. Preisgewinner seedlings, [17-D(2)]GA(20)-O-glucoside was identified by liquid chromatography (LC)/ESI-tandem mass spectrometry (MS). Likewise, by LC/ESI-tandem MS the metabolic formation of [17-D(2)]GA(20) glucosyl ester was established. The application of both [17-D(2)]-labeled GA(20) 13-O-glucoside and GA(20) glucosyl ester to Phaseolus coccineus L. seedlings resulted in free [17-D(2)]GA(20) by gas chromatography/MS. The results demonstrate that conjugation of GA(20) and the reconversion of the glucosyl conjugates are concomitant processes in plants.

Combination anesthesia with ketamine and pentobarbital: a long-term porcine model

Anesthesia of the pig poses great problems for experimental animal-based research and particularly in shock research. In this study, five mechanically ventilated domestic pigs were given long-term anesthesia with a combination of ketamine plus pentobarbital. Circulatory parameters were recorded every 2 h via an arterial catheter placed in the right common carotid artery, a Swan-Gans thermodilution catheter (7F), that was placed in the pulmonary artery of the right middle-lobe in a wedge position through the external jugular vein, and another catheter in the internal jugular vein for measuring central venous pressure. Moreover, body weight, blood gases, pH, blood cells, electrolytes and serum enzymes were measured. Further serum traits as total protein and glucose and pathological alterations in different organs were recorded. The animals were observed for a period of 96 h and then killed painlessly. It was shown that pigs can survive 96-h anesthesia with the combination of ketamine and pentobarbital. Optimum, carefully controlled anesthesia did not impair the integrity of the regulatory mechanisms of circulation.

Xanthine oxidase inhibition by allopurinol affects the reliability of urinary caffeine metabolic ratios as markers for N-acetyltransferase 2 and CYP1A2 activities

OBJECTIVES

To evaluate the in vivo effect of xanthine oxidase (XO) inhibition by allopurinol on the determination of polymorphic N-acetyltransferase 2 (NAT2) and cytochrome P450 1A2 (CYP1A2) with urinary caffeine metabolic ratios.

METHODS

In an open, prospective study involving 21 healthy subjects (eight fast, 13 slow NAT2 acetylators) allopurinol (300 mg perday) was administered orally on trial days 1-8, followed by a wash-out period of 8 days. Urinary caffeine tests (200 mg caffeine p.o.) were performed repetitively. Urine was collected for 8 h and venous blood samples for the determination of allopurinol, oxypurinol and uric acid were drawn. The urinary caffeine metabolites 1-methyluric acid (1MU), 1-methylxanthine (1MX), 1,7-dimethyluric acid (17MU), 1,7-dimethylxanthine (17MX), 5-acetylamino-6-formylamino-3-methyluracil (AFMU), plasma allopurinol and oxypurinol were analysed using high-performance liquid chromatography (HPLC).

RESULTS

During XO inhibition by allopurinol, the formation of 1MU from 1MX and therefore the XO ratio 1MU/1MX decreased to 15.9 (1.2)% [mean with (SEM)] of baseline values (P < 0.005). The NAT2 ratio AFMU/1MX decreased likewise to 56.7 (6.3)% (P < 0.005). AFMU/(AFMU + 1MX + 1MU), an alternative NAT2 ratio, remained constant, but the CYP1A2 ratio (AFMU + 1MX + 1MU)/17MU, used to express CYP1A2 activity, transiently increased to 167 (13)% (P < 0.005). The NAT2 phenotype did not influence CYP1A2 and XO ratios or plasma oxypurinol pharmacokinetics.

CONCLUSIONS

Several caffeine metabolic ratios are commonly used to express the activities of NAT2, CYP1A2 and XO both in healthy volunteers and in polymedicated patients, although their reliability has not been evaluated thoroughly during concurrent drug administration. The findings of this study suggest that NAT2 phenotyping should be performed using the ratio AFMU/(AFMU + 1MX + 1MU) if an XO inhibitor may be present. It also shows that the determination of CYP1A2 activity with caffeine as a metabolic probe is considerably altered under these conditions. Thus, concomitant drug administration may impair the robustness of multiple pathways of the complex caffeine test. This points to the need for alternative probes, designed to assess only the activity of a single enzyme because, in contrast to healthy volunteers, in patients known or unknown drug interactions may often be present.

Comparative analysis of class I, II and III epitope-detecting CD34 monoclonal antibodies by quantitative flow cytometry

The aim of this study was to compare different CD34 monoclonal antibodies (MAbs) belonging to three different classes: MY10 class I, QBend10 class II, a mixture of three selected MAbs class I and II designated as CD34 Pool, and 8G12 class III. Bone marrow (BM) samples from 13 healthy donors were analyzed for: 1) percentage of CD34+ cells, 2) quantitative expression of CD34 epitopes (antigen's density - AgD) using a quantitative indirect immunofluorescence (QIFI) test, 3) study of CD34+ cell subsets defined by CD34 and CD38 coexpression. 8G12 MAb showed the highest reactivity with regard to the percentage of detected CD34+ cells and AgD on these cells. A nearly identical percentage of CD34+ cells was detected with CD34 Pool, but with a lower AgD. With QBend10, the percentage of CD34 expressing cells was insignificantly decreased and the AgD was slightly lower. The expression of the MY10 epitope was the lowest and was detected on the lowest number of CD34+ cells. Concerning CD34 and CD38 coexpressing subset, we observed that 8G12 class III MAb detected CD34loCD38dim cells with comparable efficiency with MY10 class I MAb, but with significantly higher level than QBend10 class II and CD34 Pool class I+II MAbs. The CD34hiCD38dim subset was detected with the same efficiency by QBend10, CD34 Pool or 8G12 MAbs but with significantly higher frequency than MY10 MAb.

IN CONCLUSION

class II and III MAbs appear preferable for flow cytometric quantification of CD34+ cells; for CD34+ cell subsets determination class III MAbs should be suitable.

Provisional quality control parameters and interpretive criteria for testing susceptibility of Streptococcus pneumoniae and Haemophilus influenzae to quinupristin/dalfopristin (RP59500). Antimicrobial Testing Quality Control Group

Studies were undertaken to select tentative criteria for susceptibility testing of quinupristin/dalfopristin against Streptococcus pneumoniae and Haemophilus influenzae. Against 612 isolates of Streptococcus pneumoniae, MICs of quinupristin/dalfopristin were < or = 1.0 microg/ml for all but one strain. With a tentative MIC breakpoint of either < or = 1.0 microg/ml or < or = 2.0 microg/ml for susceptible, a disk diffusion zone diameter breakpoint of > or = 19 mm embraced all but two of the susceptible pneumococci; > or = 16 mm included all strains. For Haemophilus influenzae, MICs of quinupristin/dalfopristin clustered near the tentative breakpoints; 91.5% of the MICs were 2.0 to 8.0 microg/ml. This precluded satisfactory performance of the disk diffusion test in discriminating between resistant and susceptible isolates unless MIC breakpoints are modified for this species: clinical experience will be needed before that can be justified. Based on data from a multilaboratory study, the following quality control limits are proposed for Streptococcus pneumoniae ATCC 49619 when testing quinupristin/dalfopristin: 0.25 to 1.0 microg/ml for broth microdilution tests and 19 to 24 mm for disk diffusion tests. For tests of Haemophilus influenzae ATCC 29247, MIC limits are 2.0 to 16 microg/ml; disk tests were very reproducible but are not yet recommended.

Primary structure and functional scFv antibody expression of an antibody against the human protooncogen c-myc

The immunoglobulin heavy- and light-chain variable region (Vh and Vl) genes were isolated from Myc1-9E10 hybridoma cells, which secreted monoclonal antibody against human oncogen c-myc. The expression vector pOPE52-c-myc was constructed for the recombinant production in E. coli. A 30 kDa single chain fragment (scFv) expression product was found in the periplasmic space by SDS-PAGE and immunoblotting. A significant fraction was processed correctly as demonstrated with an antiserum recognizing the processed aminoterminus only. The specific binding of the scFv fragment to the peptide epitope of the maternal monoclonal antibody was demonstrated and the primary sequence of the variable regions was determined. Sequence comparison with previously published partial Vh and Vl sequences from this hybridoma cell line revealed a genetic heterogeneity for the light chain variable region. The potential use of this scFv as a new tool for detection and purification of tagged proteins, for adding costimulatory signals to the surface of cancer cells as well as for analyzing c-myc function in the living cell by cytoplasmic expression is discussed.

Extracellular magnesium depletion in pediatric patients with insulin-dependent diabetes mellitus

It is unclear whether insulin-dependent diabetes mellitus is a state of magnesium depletion. This is a relevant question, since magnesium deficiency has been implicated in the pathogenesis of diseases that develop to an increased extent into diabetes mellitus. Total plasma magnesium was not statistically different in 76 pediatric patients with insulin-dependent diabetes mellitus (0.77 [0.73-0.81] mmol/l; median and interquartile range), 59 healthy adults (0.80 [0.77-0.83] mmol/l) and 19 healthy children (0.80 [0.78-0.83] mmol/l). In contrast, plasma ionized magnesium, the most interesting form with respect to physiological and biological properties, was significantly lower in diabetic patients (0.50 [0.48-0.53] mmol/l) when compared with healthy adults (0.53 [0.50-0.56] mmol/l; p < 0.01) and healthy children (0.54 [0.51-0.56] mmol/l; p < 0.02). Our report confirms recent findings of reduced circulating ionized magnesium but normal circulating total magnesium in adults with non-insulin-dependent diabetes mellitus.

Cell surface display of a single-chain antibody for attaching polypeptides

To provide an efficient means of coupling proteins, peptides and other suitable moieties to cells, we have constructed a retroviral expression vector for cell surface display of a single-chain antibody (scFv) against the hapten 4-ethoxymethylene-2-phenyl-oxazo-line-5-one (phOx). The hapten phOx can be easily conjugated to primary amino and sulfhydryl groups, thus providing points of attachment for the cell surface-bound anti-phOx scFv. This universal cell coupling system could prove to be particularly useful for anchoring monoclonal antibodies for tumor targeting and to present co-stimulatory molecules and other ligands (even mixtures) at the cell surface for gene therapy.

Mechanical ventilation in stroke patients--is it worthwhile?

We assessed the therapeutic efficacy and outcome of mechanical ventilation (MV) in patients with acute respiratory failure (ARF) following ischemic stroke (IS) or intracerebral hemorrhage (ICH), retrospectively graded by patients with IS (n = 881) and ICH (n = 108) admitted to our service during 11 years, according to the severity of their clinical state and to whether we employed MV. Outcome was recorded in terms of survival and duration of MV and compared with patients with neuromuscular (NM) diseases. We found a very high in-hospital mortality in stroke patients who were treated with ventilation (90.5% for IS and 87.5% for ICH) compared with NM patients (29%). We conclude that MV in stroke patients with ARF is not life-saving, and its use should be considered only after considering other potentially important factors.

Adhesiveness of the apical surface of uterine epithelial cells: the role of junctional complex integrity

Embryo implantation necessitates that the apical plasma membrane of uterine epithelial cells acquires adhesiveness. Recent studies have indicated that modulation of a major element of the epithelial phenotype, i.e. apical-basal cell polarity, might be critical in this respect. Here, we analyze polar characteristics of nonadhesive vs. adhesive uterine epithelial cell lines focusing on cytoskeletal-junctional interactions that may play a role in regulating adhesiveness of the apical plasma membrane. HEC-1-A is a human uterine epithelial cell line exhibiting nonadhesive properties of its apical surface for trophoblast, whereas RL95-2 represent another such cell line exhibiting adhesive properties enabling trophoblast attachment. Homotypic intercellular contacts and functionally related proteins, i.e. ZO-1, E-cadherin, alpha-catenin, beta-catenin, plakoglobin, and desmoplakin 1, were examined by transmission electron microscopy, immunocytochemistry, confocal laser scanning microscopy, and immunoprecipitation techniques. In addition, details of actin filament architecture were studied after phalloidin labeling. While nonadhesive HEC-1-A exhibited the well-known pattern of cell-to-cell contacts of polarized epithelial cells, adhesive RL95-2 showed a lack of ZO-1 expression, tracer leakiness of the paracellular pathway, and atypical features in adherens junctions: E-cadherin, alpha-catenin and plakoglobin were colocalized in all plasma membrane domains and beta-catenin was localized in lateral membrane domains. Immunoprecipitations showed in both cell lines the presence of two different E-cadherin-catenin complexes, one composed of E-cadherin, alpha-catenin and beta-catenin, and the other of E-cadherin, alpha-catenin and plakoglobin. Concerning RL95-2 these data indicate that E-cadherin/plakoglobin complexes are randomly distributed, whereas E-cadherin/beta-catenin complexes are laterally localized in these cells. Additionally, the actin-based cytoskeleton of RL95-2 lacked a polar organization. With respect to the intermediate filament-desmosome system, both cell types expressed desmoplakin I, but the vast majority of RL95-2 lacked well-formed desmosomes as demonstrated by electron microscopy. It is concluded that modulation of tight junctions and/or remodelling of adherens junctions, e.g. differential distribution of E-cadherin/plakoglobin complexes and E-cadherin/beta-catenin complexes, are correlated with the development of apical adhesiveness of human uterine epithelial cells. This model system should allow to test experimentally whether this correlation is due to any causal function in the development of epithelial cell polarity.

Separation of E. coli expressing functional cell-wall bound antibody fragments by FACS

BACKGROUND

The rapid development of recombinant antibody technology in the last few years has facilitated the generation of antibody libraries in bacteria. Recombinant antibodies against various antigens have been selected from these libraries by presenting each antibody on the surface of a phagemid particle that contains the antibody's gene. An alternative screening system is the display of antibody fragments on bacteria. A major advantage is the possibility to select single cells directly from a large number of bacteria by using fluorescently labeled antigens and fluorescence assisted cell sorting (FACS).

OBJECTIVES

pAP is an expression vector for the bacterial display of antibody fragments. E. coli transformed with pAP express a single chain antibody (scFv) fused to the peptidoglycan-associated-lipoprotein (PAL). This fusion protein binds strongly to the cell wall. To employ this system for screening, we have investigated the possibility of selecting antigen-specific clones by FACS.

STUDY DESIGN AND RESULTS

Several DNA fragments coding for various scFvs were inserted into the pAP expression vector. E. coli were transformed with these plasmids and immunostained with fluorescent antigens under given conditions. We were able to select stained E. coli expressing a specific scFv from unstained E. coli expressing a non-binding scFv by FACS. The specific selection of the bacteria was demonstrated by amplifying their genes by PCR.

CONCLUSIONS

Conditions are described for separating E. coli containing scFv bound to their cell wall by FACS using fluorescently labeled antigens. These studies provide a basis for screening libraries of scFv antibodies.

Epithelial cell polarity and embryo implantation in mammals

At embryo implantation we are confronted with the fact that uterine and trophoblast epithelium make contact via their apical cell membranes. This epithelium-epithelium adhesion leading to definitive attachment of the embryo to the uterine wall, however, is far from being trivial and has been called a cell biological paradox. It has been proposed that some of the molecular events involved in epithelium-to-mesenchyme transformation might play a role in the interaction between uterine cells and trophoblast. As a mechanism to achieve uterine epithelium adhesiveness for trophoblast it is postulated that uterine cells partially modulate their epithelial phenotype. Data from recent in vitro experiments give support to this hypothesis and suggest that loss of apical-basal cell polarity might prepare the apical cell pole of uterine epithelium for cell-to-cell contact with trophoblast in vivo.

Human antibody libraries in Escherichia coli

A potentially vast pool of human antibodies with novel specificities for diagnostic and therapeutic purposes can be generated in Escherichia coli. Antibodies to infectious agents have already been isolated by amplifying the heavy and light chain repertoires of donor lymphocytes and they have even been rescued many years after the initial infection from memory cells cultivated in SCID mice. Eventually, however, the creation of extremely large and diverse libraries from the naive antibody repertoire of unactivated B lymphocytes or by gene synthesis using random oligonucleotides for the hypervariable regions could provide a rapid means of obtaining human antibodies to any particular antigen. An important breakthrough for exploiting the potential size and diversity of these libraries has been the development of systems for the surface display of antibodies that are physically linked to their own genes. This allows large numbers of clones to be screened simultaneously and antibodies with affinities of up to 10(8) M-1 have already been obtained using these vectors. It seems quite feasible, therefore, that antibodies with affinities approaching those obtained in the secondary immune response can be obtained by systematically optimizing the strategies for making antibody libraries. Furthermore, it might be possible to establish extremely large antibody repertoires in E. coli by the in vivo recombination of phage and plasmid antibody libraries. The affinity of the selected antibodies could be increased by chain shuffling or random mutagenesis followed by several rounds of selection under increasingly stringent conditions.

A single expression system for the display, purification and conjugation of single-chain antibodies

To facilitate the purification and conjugation of single-chain antibodies (scFv) selected from a phage display library, we have incorporated His6, an amber stop codon and a C-terminal Cys into a surface expression vector. The vector also contains a lacIq gene for improving the efficiency of regulation and a sequence coding for a marker peptide.

Comparative antimicrobial activities of the penem WY-49605 (SUN5555) against recent clinical isolates from five U.S. medical centers

The in vitro activity of WY-49605 (SUN5555) (WY) was compared with those of cefaclor, cefixime, and amoxicillin-clavulanic acid against 2,958 consecutive clinical isolates from five medical centers and 402 respiratory pathogens from 18 other facilities. Most members of the family Enterobacteriaceae were inhibited by WY (MIC at which 50% of the isolates are inhibited [MIC50], < or = 2.0 micrograms/ml). MIC90s of > or = 8.0 micrograms/ml were observed for Enterobacter cloacae, Serratia spp., and Proteus mirabilis. WY was the most active drug against methicillin-susceptible Staphylococcus aureus (MIC90, 0.12 microgram/ml) and other coagulase-negative staphylococci (MIC90, 4.0 micrograms/ml). The four drugs were not active against nonenteric gram-negative bacilli, methicillin-resistant Staphylococcus aureus, and Staphylococcus haemolyticus. At 2.0 micrograms/ml, WY inhibited 82% of Enterococcus faecalis strains and was equal to or superior to the other drugs against streptococci, Haemophilus influenzae, and Moraxella catarrhalis.

Cell adhesion to the apical pole of epithelium: a function of cell polarity

Human uterine epithelium displays a distinct polarized organization with apical, lateral, and basal plasma membrane domains. Although non-adhesive throughout most of the menstrual cycle, epithelial cells allow attachment of trophoblast cells to their apical pole during embryo implantation. A recent hypothesis postulates that epithelial cells turn off genes for apical-basal polarity and turn on genes for a more mesenchyme-like phenotype allowing cell-cell interaction with trophoblast. Using an in vitro assay human uterine cell lines (RL95-2, HEC-1-A, AN3-CA) were selected on the basis of adhesiveness for trophoblast-type cells (JAR). Subsequently, uterine cells were examined for epithelium-specific ultrastructure using transmission electron microscopy, and for the expression of E-cadherin, alpha 6-, beta 1-, beta 4-integrin subunits and cytokeratin using immunocytochemistry, confocal laser scanning microscopy, and surface replication technique. HEC-1-A monolayers are non-adhesive for JAR cells and appear highly polarized expressing E-cadherin, alpha 6-, beta 1-, beta 4-integrin subunits, and cytokeratin. Both, integrins and E-cadherin, are present at the lateral membrane. RL95-2 monolayers which are adhesive for JAR cells appear non-polarized. Like HEC-1-A cells, RL95-2 cells express E-cadherin, alpha 6-, beta 1-, and beta 4-integrin subunits, and cytokeratin. In contrast to HEC-1-A cells, integrins and E-cadherin are distributed at the entire cell surface. AN3-CA monolayers are non-adhesive for JAR cells and appear non-polarized. Cells lack epithelial-specific markers such as keratin and E-cadherin. They show only low expression of alpha 6-, beta 1-integrin subunits and lack beta 4-integrin subunit. Conversely, they express vimentin. Thus, modulation of the epithelial phenotype of uterine cells, i.e. loss of apical-basal polarity, might prepare the apical cell pole for cell-cell interaction with trophoblast. However, loss of cell polarity would not lead to enhancement of adhesiveness for trophoblast if accompanied by a loss of epithelium-specific adhesion molecules.

DNA measurements reveal differences in the life cycles of Babesia bigemina and B. canis, two typical members of the genus Babesia

The relative DNA levels of different developmental stages of Babesia bigemina and B. canis were measured by cytophotometry using the fluorochrome Hoechst 33258 as a staining dye. The DNA measurements provided direct proof of sexual reproduction, i.e., fusion of gametes resulting in the formation of zygotes followed by a meiotic division. Both Babesia species are considered to be typical members of the genus Babesia; however, the DNA measurements revealed important differences in the life cycle of these parasites, indicating that Babesia species are not characterized by a life cycle, which is specific for this genus.