From matrix nano- and micro-phase tougheners to composite macro-properties.

In this paper, firstly, the morphology and toughness of a range of bulk epoxy polymers, which incorporate a second phase of well-dispersed silica nanoparticles and/or rubber microparticles, have been determined. Secondly, the macro-properties of natural-fibre reinforced-plastic (NFRP) composites based upon these epoxy polymers have been ascertained, using (i) unidirectional flax fibres or (ii) regenerated-cellulose fibres in the architecture of a plain-woven fabric. Thirdly, the toughening mechanisms which are induced in these materials by the presence of the silica nanoparticles, the rubber microparticles and the natural fibres have been identified. Finally, the values of the toughness of the bulk epoxy polymers and corresponding NFRPs have been quantitatively modelled. The increased toughness recorded for the bulk epoxy polymer due to the presence of the silica nanoparticles and/or rubber microparticles was indeed typically transferred to the NFRP composites when using such epoxies as the matrices for the fibres. Thus, the important role that may be played by modifications to the epoxy matrices in order to increase the toughness of the composites was very clearly demonstrated by these results. However, notwithstanding, the toughening mechanisms induced by the fibres were essentially responsible for the very high toughnesses of the NFRP composites, compared with the bulk epoxy polymers. The modelling studies successfully predicted the values of toughness of the bulk epoxy polymers and of the NFRP composites. These studies also quantified the extent to which each toughening mechanism, induced by the second-phase nano- and microparticles and the natural fibres, contributed to the overall values of toughness of the materials. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

Identification of subgroups of high-grade oligodendroglial tumors by comparative genomic hybridization.

In contrast to astrocytic tumors, approximately two thirds of anaplastic oligodendrogliomas are reported to be chemosensitive. Relatively little is known about the genetic aberrations in oligodendroglial tumors (OTs). In order to elucidate oligodendroglial oncogenesis and to find specific genetic aberrations that may have prognostic and therapeutic implications, we performed comparative genomic hybridization (CGH) to detect chromosomal copy number changes in 17 low-grade OTs (LG-OTs) and 12 high-grade OTs (HG-OTs) lacking a prominent astrocytic component. Loss of chromosome 1p (79%) and 19q (76%) were most frequently detected by CGH, all LG-OTs and 50% of the HG-OTs contained -1p (including 1p36-32), -19q (including 19q13.3), or both, and the rest of the HG-OTs showed +7, -10, or both. Since losses of 1p36-32 and 19q13.3 were mutually exclusive with +7 or -10, the HG-OTs could be divided in -1p/-19q and +7/-10 tumors. While the -1p/-19q tumors can be considered as pure anaplastic oligodendrogliomas, the +7/-10 tumors may rather be glioblastomas with prominent oligodendroglial differentiation. We conclude that CGH is a powerful tool to assist in the identification of 2 major subgroups of HG-OTs with prognostic and possibly therapeutic relevance.

Frequent loss of 9p21 (p16(INK4A)) and other genomic imbalances in human malignant fibrous histiocytoma.

To search for new recurrent genetic aberrations in malignant fibrous histiocytoma (MFH), a combination of conventional cytogenetic, comparative genomic hybridization (CGH), and Southern blot analyses was applied to a series of 34 tumors. Cytogenetic analysis revealed the presence of multiple structural and numerical aberrations, including marker chromosomes, telomeric associations, double minutes, and ring chromosomes. The most frequent genomic imbalances in this series of neoplasms as detected by CGH were gains of 1q21-q22 (69%), 17q23-qter (41%), and 20q (66%), and losses of 9p21-pter (55%), 10q (48%), 11q23-qter (55%), and 13q10-q31 (55%). Southern blot analyses with p16(INK4A) (CDKN2A; 9p21) and RB1 (13q14) probes provided clear indications for frequent deletions of these tumor suppressor genes, and as such, substantiated the CGH results. Additionally, examination of the TP53 and MDM2 genes showed frequent loss and amplification, respectively. These data indicate that genes involved in the RB1- and TP53-associated cell cycle regulatory pathways may play prominent roles in the development of human MFH.

Genetic reflection of glioblastoma biopsy material in xenografts: characterization of 11 glioblastoma xenograft lines by comparative genomic hybridization.

OBJECT: Human tumors implanted as subcutaneous xenografts in nude mice are widely used for the study of tumor biology and therapy. Validation of these models requires knowledge of the genetic makeup of the xenografts. The aim of this study was to establish whether chromosomal imbalances in 11 xenograft lines derived from human glioblastomas multiforme (x-GBMs) are similar to those found in GBM biopsy samples. The authors also studied genetic stability during serial passaging of three xenograft lines. METHODS: Chromosomal imbalances in x-GBMs were detected using comparative genomic hybridization (CGH). The authors compared the CGH results in x-GBMs with those in the original GBMs (o-GBMs) that were used to establish three of the xenograft lines and with the GBM biopsy results reported in the literature (1-GBMs). In three xenograft lines two different passages were analyzed. CONCLUSIONS: The results show that the chromosomal imbalances in x-GBMs are similar to those in o-GBMs and 1-GBMs, indicating that the GBM xenograft lines used were valid models from a genetic point of view. The CGH analysis of two different passages of three xenograft lines indicates that x-GBMs (like 1-GBMs) show intratumoral genetic heterogeneity and do not acquire chromosomal imbalances as a result of serial passaging.

Ornithobacterium rhinotracheale infection in turkeys: immunoprophylaxis studies.

Ornithobacterium rhinotracheale has been shown to cause serious clinical illness and is a significant concern to the turkey industry because of its potential economic impact. In this study, 6-wk-old turkeys were vaccinated intranasally with a live or subcutaneously with a killed O. rhinotracheale vaccine. At 14 or 21 wk of age, the birds were challenged intratracheally with live O. rhinotracheale. Airsacculitis and pneumonia occurred less frequently in vaccinated birds than in unvaccinated birds after challenge with O. rhinotracheale. Ornithobacterium rhinotracheale was recovered from unvaccinated, challenged birds but not from vaccinated, challenged or from unchallenged birds. Thus, turkeys inoculated with live or killed O. rhinotracheale vaccine were protected from pathologic changes.

Ornithobacterium rhinotracheale infection in turkeys: experimental reproduction of the disease.

This report details the first experimental production of clinical disease, mortality, and pathology resembling that of field infections by using Ornithobacterium rhinotracheale alone. Twenty-two-week-old male turkeys were exposed to O. rhinotracheale or lung homogenate from O. rhinotracheale-infected turkeys. Within 24 hr after inoculation, turkeys given O. rhinotracheale or lung homogenate intratracheally were depressed and coughing and had decreased feed intake. By 48 hr, several birds were coughing blood and ultimately died. Grossly, the lungs were reddened, wet, and heavy, failed to collapse, and were covered by tenacious tan-to-white exudate. Microscopically, the parabronchi and air capillaries were filled with fibrin, heterophils, macrophages, and small numbers of gram-negative bacteria. The pleura was often covered by a thick layer of fibrin, heterophils, and macrophages. Turkeys that survived to day 7 postinoculation had severe, subacute pneumonia. Ornithobacterium rhinotracheale was recovered from the lungs of most birds with pneumonia and was also cultured from the air sacs, sinuses, tracheas, spleens, and livers. All turkeys inoculated with O. rhinotracheale developed antibodies to O. rhinotracheale detectable by the serum plate agglutination test.

Isolation and identification of Ornithobacterium rhinotracheale from commercial turkey flocks in the upper midwest.

Increased death loss was seen in a flock of 22-wk-old tom turkeys. The predominant postmortem lesion was fibrinopurulent pneumonia and pleuritis. Within 5 wk, turkey flocks on 17 other farms developed similar problems. All affected flocks during the 5-wk period were between 14 and 22 wk of age, and the severity of clinical signs and the degree of mortality increased with age. Ornithobacterium rhinotracheale was isolated in pure culture from affected lungs. Further investigation by tracheal swab culture of 261 flocks between 5 and 7 wk of age resulted in detection of O. rhinotracheale in 43% of the flocks.

Ornithobacterium rhinotracheale infection in commercial laying-type chickens.

Ornithobacterium rhinotracheale is a gram-negative, rod-shaped, pleomorphic bacterium that has been isolated from flocks of turkeys and broilers from around the world. Infections cause respiratory disease, mortality, and growth suppression, or clinical signs of infection may be absent. In layers, there have been few reports of disease caused by O. rhinotracheale. This is the first report of O. rhinotracheale infection in United States layer flocks.

Evidence for the occurrence of nucleotide-activated oligosaccharides in Saccharomyces cerevisiae.

Recently, nucleotide-activated oligosaccharides have been found to be involved in the biosynthesis of certain glycoconjugates in archaeal and bacterial procaryotes. This paper describes the isolation and partial chemical characterization of nucleotide-activated oligosaccharides from the eucaryotic microbe Saccharomyces cerevisiae. We purified four different nucleotide-activated oligosaccharides from cell extracts of Saccharomyces cerevisiae. Three of the oligosaccharides were UDP, and one was TDP-activated. D-Glucose was the only carbohydrate constituent, except for one oligosaccharide, which also contained glucosamine. The chain length varied between two and four sugar residues.

Phosphate is essential for stimulation of V gamma 9V delta 2 T lymphocytes by mycobacterial low molecular weight ligand.

T lymphocytes are divided into two subsets which express different T cell receptor heterodimers. In the peripheral blood of healthy individuals, the majority of T cells express the alpha/beta T cell receptor (> 90%) while a minority have the gamma/delta T cell receptor (< 10%). The gamma/delta T cells of adults use preferentially the V gamma 9V delta 2 chain combination. Although the stimulation requirements for gamma/delta T lymphocytes are still undetermined, it has been reported that gamma/delta T cells are not only stimulated, like alpha/beta T cells, by conventional protein antigens and superantigens, but also by unusual ligands. Mycobacteria selectively stimulate V gamma 9V delta 2 T cells, and a nonproteinacious low molecular weight fraction of 1-3 kDa has been identified as the tentative active component. Here, we confirm the nonproteinacious nature of this ligand, and show that it is comprised of unusual carbohydrate and phosphate. Importantly, cleavage of the terminal phosphate by alkaline phosphatase completely abrogates the stimulatory activity of the low molecular weight ligand for V gamma 9V delta 2 T cells. Even mycobacterial whole lysate loses its stimulatory activity, for this T cell subset, after dephosphorylation with alkaline phosphatase. These findings identify phosphocarbohydrates as a novel molecular entity with selective stimulatory activity for a defined T cell subset.

Characteristic chromosomal aberrations in sporadic cerebellar hemangioblastomas revealed by comparative genomic hybridization.

Hemangioblastomas (HBs) of the central nervous system are benign tumors and occur as sporadic (sp) tumors (75%) or as a manifestation of the von Hippel-Lindau (VHL) disease (25%). VHL-disease is an autosomal dominant disorder characterized by HBs of the central nervous system and retina, renal cell carcinoma (RCC), phaeochromocytoma (PHEO), islet tumors of the pancreas, and endolympatic sac tumors as well as cysts and cystadenoma in the kidney, pancreas and epididymis. In VHL patients a large spectrum of germline mutations in the VHL gene has been detected. In spHBs VHL alleles are reported to be inactivated in up to 50% of the tumors. To our knowledge the involvement of other genes in spHBs has not been investigated. To elucidate the oncogenesis of spHBs, we performed CGH on 10 spHBs to screen for chromosomal imbalances throughout the entire tumor genome. Aberrations most frequently detected are losses of chromosomes 3 (70%), 6 (50%), 9 (30%), and 18q (30%) and a gain of chromosome 19 (30%). Based on these frequencies and the co-occurrence of these aberrations in the analyzed tumors we hypothesize that loss of chromosome 3 (harboring the VHL gene) is an early event in the oncogenesis of spHBs, followed by loss of 6, and then losses of chromosomes 9, 18q and gain of chromosome 19. Comparison of the chromosomal imbalances in spHBs to those previously reported in RCCs and PHEOs reveals that the pathway of spHBs shows similarities to both the RCCs and PHEOs.

[Experience with three minipills preparations with low dose progestagens for oral contraception]. / Erfahrungen mit drei minipillen Praparate mit niedrig dosierten Progestagenen zur oralen Kontrazeption.

PIP: 208 Swiss and Finnish women took the progestagen-only minipills megestrol acetate .5 mg, chlormadinone acetate .5 mg, or D-norgestrel .03 mg for an average of 5 months. Withdrawal bleeding lasted longer, 5.2-5.3 days (mean) than with conventional pills, 4.6 days. Nausea occurred less frequently, 8.5% in the 1st cycle compared with 25%. Loss of libido was reported about as often as with sequential pills. Breakthrough bleeding at intervals of 21 days or less happened in 225 wi th chlormadinone, 28% with norgestrel, and 8% with megestrol. Spotting was reported in 27% of the cycles on megestrol, 18% on chlormadinone, and 14.5% on norgestrel. The time interval from 1 withdrawal bleeding to the next averaged 29.1 days with megestrol, 25.6 days with chlormadinone, and 24.5 days with norgestrel. The variance of this interval was comparable to the 3 progestagens, but about half as large in Finnish women as in Swiss, indicating that the dose used was too high in the Swiss population.^ieng

The relationship between genetic aberrations as detected by comparative genomic hybridization and vascularization in glioblastoma xenografts.

Angiogenesis is of vital importance for the growth of solid tumors and constitutes a target for anti-cancer therapy. Glioblastomas (GBMs) are histologically characterized by striking microvascular proliferation. The identification of the mechanism of angiogenesis is of major importance for the further development of anti-angiogenic therapy. Tumor angiogenesis might be the result of a combination of local tissue conditions (especially hypoxia) and specific genetic alterations acquired during oncogenesis. In order to investigate the relationship between genetic aberrations and tumor angiogenesis in GBM xenograft lines, the genetic alterations were examined by Comparative Genomic Hybridization (CGH). Two vascular phenotypes of GBM xenografts could be identified: a well vascularized and a poorly vascularized type. In this model, the poorly vascularized type had a larger number of genetic alterations. However, there was no unequivocal correlation between angiogenesis, growth rate and patterns of genetic alterations as detected by CGH.

Subtyping of oligo-astrocytic tumours by comparative genomic hybridization.

Oligo-astrocytic tumours (OAs) histologically show both oligodendroglial and astrocytic differentiation. Unequivocal criteria for delineation of OAs from pure oligodendroglial (Os) and astrocytic (As) tumours and for grading of OAs are lacking. Molecular genetic analysis may allow for a better characterization of OAs and thereby guide prognostic and therapeutic decisions. Comparative genomic hybridization (CGH) was performed on 39 gliomas with variable phenotypic expression of histological features characteristic of both astrocytic and oligodendroglial differentiation. The results show that OAs are genetically more heterogeneous than Os. In addition to the "-1p/-19q" and "+7/-10" subtypes that have been previously recognized, two additional genetic subtypes, "intermediate" and "other", were identified in the present study. "Intermediate" OAs likely represent progression from "-1p/-19q" tumours. The "other" subtype appears to represent an additional, heretofore unrecognized, genetic pathway(s). Application of rigorously "strict" histopathological criteria, as opposed to "relaxed" criteria, for the selection of oligo-astrocytic tumours resulted in a higher percentage of "-1p/-19q" tumours, but some "-1p/-19q" tumours might be missed. The results suggest that molecular genetic analysis is a useful and valid additional tool for the classification of gliomas, particularly for the significant subset of tumours in which subjective histopathological criteria are insufficient for an unequivocal distinction between Os, As, and mixed OAs.

Molecular analysis of a familial case of renal cell cancer and a t(3;6)(q12;q15).

We identified a novel familial case of clear-cell renal cancer and a t(3;6)(q12;q15). Subsequent cytogenetic and molecular analyses showed the presence of several abnormalities within tumour samples obtained from different patients. Loss of the der(3) chromosome was noted in some, but not all, of the samples. A concomitant VHL gene mutation was found in one of the samples. In addition, cytogenetic and molecular evidence for heterogeneity was obtained through analysis of several biopsy samples from one of the tumours. Based on these results and those reported in the literature, we conclude that loss of der(3) and subsequent VHL gene mutation may represent critical steps in the development of renal cell cancers in persons carrying the chromosome 3 translocation. Moreover, preliminary data suggest that other (epi)genetic changes may be related to tumour initiation.