Stressful life events preceding the acute onset of schizophrenia: A cross-national study from the World Health Organization

This study reports on the findings from a WHO sponsored cross-national investigation of life events and schizophrenia. Data are presented from a series of 386 acutely ill schizophrenic patients selected from nine field research centers located in developing and developed countries (Aarhus, Denmark; Agra, India; Cali, Colombia; Chandigarh, India; Honolulu, USA; Ibadan, Nigeria; Nagasaki, Japan; Prague, Czechoslovakia; Rochester, USA). On a methodological level, the study demonstrates that life event methodologies originating in the developed countries can be adapted for international studies and may be used to collect reasonably reliable and comparable cross-cultural data on psychosocial factors affecting the course of schizophrenic disorders. Substantive findings replicate the results of prior studies which conclude that socioenvironmental stressors may precipitate schizophrenic attacks and such events tend to cluster in the two to three week period immediately preceding illness onset.The paper was prepared by these authors on behalf of the collaborating investigators listed on page 196.     

Changes in the proliferation of human lymphocytes induced by several cytostatics and revealed by the premature chromosome condensation technique

Premature chromosome condensation was induced by cell fusion in stimulated human lymphocytes treated with different cytostatics. Changes in the proportion of the cell-cycle stages were investigated after 72 h of culture. Although it has been reported that some agents which induce severe DNA damage accumulate cells in G2, our results have shown some differences in the modes of action of the different tested chemicals. These variations could be due to several factors like mechanisms of action of the drugs, sensitivity of lymphocyte subpopulations to the cytostatics, inter- and intra-individual variability in the response of donors.     

Chromosome painting for cytogenetic monitoring of occupationally exposed and non-exposed groups of human individuals

The suitability of a three-color fluorescence in situ suppression hybridization technique was examined for monitoring five different groups of individuals: 30 occupied in radiology, 26 occupied in nuclear medicine or radiation physics, 32 patients with breast cancer, 26 occupied with military waste disposal, all presumably exposed to low doses of radiation or chemical mutagens and a non-exposed control group (N=29). The average frequency of breaks constituting the various aberrations did not significantly differ between the groups of medical radiation appliers and the control group. However, breast tumor patients and military waste disposers, as groups, showed a higher aberration rate than did healthy controls. Stable rearrangements mainly characterized the groups of controls, tumor patients, and radiation appliers, while a higher proportion of unstable aberrations was found in the chemically exposed individuals. Individuals with an increased frequency of aberrations could be detected within each examined group, which clearly determined the average values of the whole group. With respect to interchromosomal distribution of the breakpoints constituting the found aberrations and the involvement of the labeled chromosomes in rearrangements, the observed values were very close to the expected ones in the controls. A rather similar trend of deviations from expectation was observed in all other groups. Chromosome 4 was slightly over-affected, while chromosome 2 was slightly underrepresented in all analyzed groups (except tumor patients). Rearrangements of the labeled chromosomes with the unlabeled ones exceeded expectation. In conclusion, chromosome painting if included in further attempts of human population monitoring will broaden the basis of argumentation with respect to health risks introduced by mutagen exposure.     

Physical Changes of Amniotic Membranes Through Glycerolization for The Use as an Epidermal Substitute. Light and Electron Microscopic Studies

Our Department of Plastic and Reconstructive Surgery has routinely been using amnion preserved in glycerol for the treatment of debrided II° burns. This treatment is almost pain free and requires fewer changes of dressings and fewer anaesthetics. It also prevents overgrowing granulation tissue and lessens scarring. Since 1910 amnion has been used as biological wound dressing. Its advantages such as reduced loss of protein and electrolytes, fluids and energy as well as reducing the risk of infection and accelerated regeneration of the epithelium have been well documented in medical literature. In order to more closely examine the question of possible changes to the micro structure of the amnion through preservation and rehydration as well as the interaction between transplanted tissue and recipient, we have carried out several light and electron microscopic studies. Results showed that neither the treatment with glycerol, nor the pretransplantation rehydration eliminates the monolayer of surface epithelium of the amnion. Its complex architecture remains intact during the preservation process and is therefore suitable as a matrix for the growth of keratinocytes and thereby the healing process. In clinical use we found amnion to be an excellent wound dressing as it allows proper control of fluid, has sufficient permeability for gases, has good thermal properties, is impervious to micro-organisms and is free from toxic material. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparative M-FISH and CGH analyses in sensitive and drug-resistant human T-cell acute leukemia cell lines

Cell lines of human T-cell acute lymphoblastic leukemias (T-ALL) have gained high interest for study of mechanisms of cytostatic drug resistance. However, they should also be suited to examine the validity and reliability of molecular cytogenetic techniques in detecting genomic alterations in neoplastic cells. Therefore, comparative genomic hybridization (CGH) and 24-color-fluorescence-in-situ-hybridization (M-FISH) were applied to eight sublines of CCRF-CEM leukemia cells selected in vitro for drug resistance and to their drug-sensitive parental counterparts. All cell lines were characterized by altered chromosome numbers and by a variety of chromosomal structural aberrations as shown by M-FISH. The great majority of anomalies detected by this technique were confirmed by CGH. Interestingly, a considerable number of the rearrangements found were imbalanced. Amplifications of 5q13 in the six methotrexate-resistant cell lines, a del(9)(p21pter) in all lines examined, and a gain of chromosome 20 in 9 of the 10 lines examined were readily detected by both techniques. The same held true for losses of chromosomes 17 and 18 in the near tetraploid cell lines which could also be confirmed by CGH. Some imbalances of genomic material detected by CGH were, however, not observed by means of M-FISH, possibly due to the limited extension of the corresponding chromosomal segment involved or the small subpopulation of cells affected. On the other hand, reciprocal translocations, balanced isochromosomes, and small deletions remained mainly undetected by CGH. A comparison of chromosomal alterations in drug-resistant and parental cell lines showed not only amplifications of chromosomal segments harboring well-known drug resistance genes, e.g., the dihydrofolate reductase gene, but also chromosomal changes which may involve novel genes associated with drug resistance. Thus, the present study has clearly unveiled the strengths and weaknesses of both techniques which can excellently complement each other. Their combination allowed a distinct improvement of the definition of the complex karyotypes of drug-resistant cell lines.     

Design and formulation of polyplexes based on pluronic-polyethyleneimine conjugates for gene transfer

Previously, we reported the evaluation of several polyplex-based gene delivery systems with respect to their effectiveness, toxicity, and cell type dependence in vitro. One system, P123-g-PEI(2K), a cationic graft block copolymer, is of particular interest as it has been demonstrated to successfully deliver genetic material to murine liver following systemic delivery [Nguyen, H. K., Lemieux, P., Vinogradov, S. V., Gebhart, C. L., Guerin, N., Paradis, G., Bronich, T. K., Alakhov, V. Y., and Kabanov, A. V. (2000) Evaluation of Polyether-Polyethyleneimine Graft Copolymers as Gene Transfer Agents. Gene Ther. 7, 126-138 (1)]. The P123-g-PEI(2K) system requires nonmodified Pluronic P123 as an excipient to stabilize the dispersion. The purpose of the current work was to more closely characterize this system, to assess the role of each component of the system to the overall transfection process. We evaluated particle size, stability, and resistance to nuclease degradation. In addition, cellular uptake and localization of plasmid, as well as transgene expression, were evaluated following in vitro transfection of prostate cancer cells (PC-3) with various individual components of the system. Nonmodified Pluronic alone did not significantly enhance DNA uptake, transgene expression, or DNase protection. Therefore, we conclude that nonmodified Pluronic acted primarily by optimizing the size of the polyplex. Furthermore, though this system displays several characteristics thought desirable of a nonviral gene delivery system, these studies did discriminate a potential limitation of this system for in vivo applications, namely, the insufficient level of protection of plasmid DNA from nuclease degradation. This may limit the effective dose delivered, as well as limiting the effective circulation time. These studies provide vital information that will guide modification of this system to enhance the current in vivo profile.     

Interactions between peptidoglycan and the ExeAB complex during assembly of the type II secretin of Aeromonas hydrophila

Aeromonas hydrophila transports extracellular protein toxins via the type II secretion system, an export mechanism comprised of numerous proteins that spans both the inner and outer membranes. Two components of this secretion system, ExeA and ExeB, form a complex in the inner membrane that functions to locate and/or assemble the ExeD secretin in the outer membrane. In the studies reported here, two-codon insertion mutagenesis of exeA revealed that an insertion at amino acid 495 in the C-terminal region of ExeA did not alter ExeAB complex formation yet completely abrogated its involvement in ExeD secretin assembly and thus rendered the bacteria secretion negative. In silico analysis of protein motifs with similar amino acid profiles revealed that this amino acid is located within a putative peptidoglycan (PG) binding motif in the periplasmic domain of ExeA. Substitution mutations of three highly conserved amino acids in the motif were constructed. In cells expressing each of these mutants, the ability to assemble the ExeD secretin or secrete aerolysin was lost, while ExeA retained the ability to form a complex with ExeB. In in vivo cross-linking experiments, wild-type ExeA could be cross-linked to PG, whereas the three substitution mutants of ExeA could not. These data indicate that PG binding and/or remodelling plays a role in the function of the ExeAB complex during assembly of the ExeD secretin.