In vivo autofluorescence imaging of early cancers in the human tracheobronchial tree with a spectrally optimized system

The changes in the autofluorescence characteristics of the bronchial tissue is of crucial interest as a cancer diagnostic tool. Evidence exists that this native fluorescence or autofluorescence of bronchial tissues changes when they turn dysplastic and to carcinoma in situ. There is good agreement that the lesions display a decrease of autofluorescence in the green region of the spectrum under illumination with violet-light, and a relative increase in the red region of the spectrum is often reported. Imaging devices rely on this principle to detect early cancerous lesions in the bronchi. Based on a spectroscopic study, an industrial imaging prototype is developed to detect early cancerous lesions in collaboration with the firm Richard Wolf Endoskope GmbH, Germany. A preliminary clinical trial involving 20 patients with this spectrally optimized system shows that the autofluorescence can help to detect most lesions that would otherwise have remained invisible to an experienced endoscopist under white light illumination. A systematic off line analysis of the autofluorescence images pointed out that real-time decisional functions can be defined to reduce the number of false positive results. Using this method, a positive predictive value (PPV) of 75% is reached using autofluorescence only. Moreover, a PPV of 100% is obtained, when combining the white light (WL) mode and the autofluorescence (AF) mode, at the applied conditions. Furthermore, the sensitivity is estimated to be twice higher in the AF mode than in WL mode.     

Individual T cells hold unexpected clues to the nature of anergy and memory

The primary interest of our laboratory is understanding how the signals that a T cell receives influence its behavior during an immune response. Recently, we have focused our attention on the examination of T cell responses at an individual cell level. This article outlines our approach, presents our initial findings, and discusses the implications of these findings relative to our current models of T cell activation.     

Biologic activity of guinea pig IFN-gamma in vitro.

Interferon-gamma (IFN-gamma) plays a key role in the induction and maintenance of immunity against intracellular infectious agents. Compared to other species, little is known about the biology of this cytokine in the guinea pig (Cavia porcellus). We found that in contrast to humans and mice, IFN-gamma in the guinea pig did not induce the antiviral state, which in other species leads to protection of IFN-gamma -stimulated fibroblasts from the cytopathic effect (CPE) of subsequent viral infections. As an alternative strategy to detect and quantify guinea pig IFN-gamma activity in vitro, a reporter system using guinea pig fibroblasts transfected with a luciferase gene, which is regulated by an IFN-stimulated response element (ISRE), was established. With the help of the highly sensitive reporter assay system, the biologic activity of recombinant guinea pig IFN-gamma (GpIFN-gamma, from prokaryotic and eukaryotic expression systems was detected. The response to both native and recombinant GpIFN-gamma was inhibited by a rabbit antiserum directed against the recombinant cytokine expressed in Escherichia coli, demonstrating structural and functional homology of native and recombinant GpIFN-gamma. Stimulation with GpIFN-gamma, obtained from transfected cells, induced upregulation of MHC class I expression in a guinea pig fibroblast line. The restricted activity of GpIFN-gamma might have implications for this species' ability to control infections with intracellular pathogens.     

Genetic and physical characterization of the early-onset Alzheimer's disease AD3 locus on chromosome 14q24.3

Genetic linkage studies have provided significant evidence thata major gene defect, AD3, for familial early-onset Alzheimer'sdisease (EOAD) is located at chromosome 14q24.3, between theshort tandem repeat (STR) markers D14S52 and D14S53 defininga genetic size of 22.7 cM for the AD3 candidate region. We constructeda physical map of the AD3 region using yeast artificial chromosomes(YACs) selected from both the CEPH and megaCEPH YAC librariesusing the AD3 linked STR markers as well as new sequence-taggedsites (STSs) designed based on YAC terminal sequences. The YACmap is contiguous in the region between D14S258 and D14S53,a region of 8.2 cM, and has an estimated physical size of 4–8Mb. The YAC contig map was used as a framework to localize threeknown genes, a pseudogene and two brain expressed sequence tags(ESTs). Linkage analysis studies in two Belgian chromosome 14EOAD families AD/A and AD/B, identified obligate recombinantsin family AD/A with D14S289 and D14S61 reducing the geneticsize of the candidate AD3 region substantially. The minimalAD3 candidate region measured 6.4 cM on the genetic map andis contained within six overlapping megaCEPH YACs that covereda physical distance estimated between 2 and 6 Mb. These YACsas well as other YACs in the YAC contig map are valuable resourcesin gene cloning efforts or genomic sequencing experiments aimingat isolating the AD3 gene.     

Human malignant mesothelial cells: Variability of ultrastructural features in established and nude mice transplanted cell lines

The aim of this study was to determine, by transmission electron microscopy, the differentiation features of 21 human malignant mesothelioma cell lines (HMCLs) established from 13 specimens of 12 confirmed human malignant mesotheliomas, and of tumours induced in nude mice injected with 16 HMCLs. Fifty per cent of HMCLs showed typical mesothelial differentiation (long and slender microvilli, desmosomes, perinuclear intermediate filaments); 29 per cent did not show differentiation; and the remainder were poorly differentiated. Three human tumour specimens gave several different HMCLs; the cell lines obtained from a given tumour exhibited variable mesothelial differentiation. Eleven HMCLs were compared with the native tumour. Four were similar to the tumour and seven were less well differentiated, in most cases in relation to their microvilli. With six HMCLs, tumours induced in nude mice were less well differentiated than the corresponding cell lines, whereas with four HMCLs, tumours were equally or better differentiated. However, in most nude mice tumours, typical mesothelial microvilli were present. These results show that cell lines established from malignant mesothelioma may exhibit dedifferentiated features. However, while the variability in ultrastructural differentiation may result from the culture microenvironment, it could also be related to the state of differentiation, of the native tumour sample and to tumour cell heterogeneity.