Healing of experimental aneurysms. II: Platelet extracts can increase the thickness of the neointima at the neck of treated aneurysms.

Purpose: To assess the effect of platelet extracts (PE) on neointima formation following gelfoam packing of experimental porcine aneurysms. A strategy involving the local delivery of platelet growth factors may potentially improve long term results of endovascular treatment of aneurysms.

Methods: Bilateral lateral wall common carotid aneurysms were constructed on 30 pigs.

Healing mechanisms in experimental aneurysms. I. Vascular smooth muscle cells and neointima formation.

Purpose: The purpose of this work is to better define healing phenomena in this model, in an effort to find strategies to improve long term results of endovascular treatment.

Methods: Lateral wall venous pouch aneurysms were constructed on both carotid arteries in 30 pigs. The aneurysms were packed with collagen sponges per-operatively in 25 animals.

Lymphocyte activation gene-3, a MHC class II ligand expressed on activated T cells, stimulates TNF-alpha and IL-12 production by monocytes and dendritic cells.

Lymphocyte activation gene-3 (LAG-3) is an MHC class II ligand structurally and genetically related to CD4. Although its expression is restricted to activated T cells and NK cells, the functions of LAG-3 remain to be elucidated. Here, we report on the expression and function of LAG-3 on proinflammatory bystander T cells that are activated in the absence of TCR engagement.

The vitronectin receptor and its associated CD47 molecule mediates proinflammatory cytokine synthesis in human monocytes by interaction with soluble CD23.

The vitronectin receptor, alphavbeta3 integrin, plays an important role in tumor cell invasion, angiogenesis, and phagocytosis of apoptotic cells. CD47, a member of the multispan transmembrane receptor family, physically and functionally associates with vitronectin receptor (VnR). Although vitronectin (Vn) is not a ligand of CD47, anti-CD47 and beta3 mAbs suppress Vn, but not fibronectin (Fn) binding and function.

[Resection of the anterior cruciate ligament of the knee using arthroscopy induces arthrosis in dogs. Validity of the Pond-Nuki model].

Introduction And Goal: The dog model of osteoarthritis is the one most used for the study of the pathophysiology of this disease, given its resemblance to human osteoarthritis. Although the percutaneous section of the ligament is the most known technique, variability of and iatrogenic lesions might occur. The goal of this study was to validate the arthroscopic technique regarding the osteaorthritic lesions found in the percutaneous Pond-Nuki dog model.

Wild-type egr1/Krox24 promotes and dominant-negative mutants inhibit, pluripotent differentiation of p19 embryonal carcinoma cells.

The zinc-finger transcription factor Krox24 was analysed for its role in differentiation in P19 embryonal carcinoma cells. Reciprocal dominant negative mutants consisting of Krox24 deleted for a crucial region of the zinc-finger domain (delta Krox24) or of the zinc-finger region alone (delta Krox24Zf) abolished the activation of transcription by Krox24 in P19 cells. Expression of Krox24 led to spontaneous differentiation of P19 cells in a lineage-independent fashion.

OX40 costimulation enhances interleukin-4 (IL-4) expression at priming and promotes the differentiation of naive human CD4(+) T cells into high IL-4-producing effectors.

Th2 cell development is critically dependent on the presence of interleukin-4 (IL-4) at priming. The cellular origin and the mechanisms regulating this early production of IL-4 at the site of naive T-cell priming are extensively investigated. We previously reported that anti-CD3-activated and CD28-costimulated naive human CD4(+) T cells themselves release very low but sufficient levels of IL-4 to support their development into high IL-4-producing cells.

Collagenase-1 and collagenase-3 synthesis in normal and early experimental osteoarthritic canine cartilage: an immunohistochemical study.

Objective: The coexistence of different collagenases in cartilage suggests the possibility of specific roles for these enzymes in the degradation of the collagen network in osteoarthritis (OA). We investigated the in situ synthesis and distribution of collagenase- and collegenase-3 in normal and early experimental OA cartilage.

Methods: The OA model was created on 12 mongrel dogs by sectioning the anterior cruciate ligament of the right stifle joint with a stab wound.

Maturation of human neonatal CD4+ and CD8+ T lymphocytes into Th1/Th2 effectors.

The increased susceptibility of neonates to infections has been ascribed to the immaturity of their immune system. More particularly, T cell-dependent responses were shown to be biased towards a Th2 phenotype. Our studies on the in vitro maturation of umbilical cord blood T cells suggest that the Th2 bias of neonatal response cannot be simply ascribed to intrinsic properties of neonatal T cells.

Molecular genetics of the hereditary ataxias.

One of us (MP) learned about the mapping of Huntington disease gene to chromosome 4 from the late Dr. Anita Harding. She got the news over the phone from her London office during a visit to Italy for a meeting on hereditary ataxias.

Inhibitory effects of expanded GAA.TTC triplet repeats from intron I of the Friedreich ataxia gene on transcription and replication in vivo.

Friedreich ataxia (FRDA) is associated with the expansion of a GAA. TTC triplet repeat in the first intron of the frataxin gene, resulting in reduced levels of frataxin mRNA and protein. To investigate the mechanisms by which the intronic expansion produces its effect, GAA.

Productive infection of neonatal CD8+ T lymphocytes by HIV-1.

CD8+ T lymphocytes confer significant but ultimately insufficient protection against HIV infection. Here we report that activated neonatal CD8+ T cells can be productively infected in vitro by macrophage-tropic (M-tropic) HIV-1 isolates, which are responsible for disease transmission, whereas they are resistant to T cell-tropic (T-tropic) HIV strains. Physiological activation of CD8-alpha/beta+ CD4- T cell receptor-alpha/beta+ neonatal T cells, including activation by allogeneic dendritic cells, induces the accumulation of CD4 messenger RNA and the expression of CD4 Ag on the cell surface.

Analysis of the p16 tumor suppressor gene in early-stage prostate cancer.

To identify whether alterations of the p16 tumor suppressor gene are a common event in localized prostate cancer, we examined the frequency of p16 gene mutations in 30 primary tumors. Only two tumors demonstrated altered single-strand conformation polymorphism patterns for exon 2 of p16. In both cases, sequencing revealed a missense at codon 148, a G-->A transition that resulted in the replacement of the alanine by threonine.

Prostaglandin E2 primes naive T cells for the production of anti-inflammatory cytokines.

In addition to their capacity to induce pain, vasodilatation and fever, prostaglandins E (PGE) exert anti-inflammatory activities by inhibiting the release of pro-inflammatory cytokines by macrophages and T cells, and by increasing interleukin (IL)-10 production by macrophages. We here report that PGE2, the major arachidonic acid metabolite released by antigen-presenting cells (APC), primes naive human T cells for enhanced production of anti-inflammatory cytokines and inhibition of pro-inflammatory cytokines. Unfractionated as well as CD45RO- CD31+ sort-purified neonatal CD4 T cells acquire the capacity to produce a large spectrum of cytokines after priming with anti-CD3 and anti-CD28 monoclonal antibodies (mAb), in the absence of both APC and exogenous cytokines.

Expression and function of OX40 ligand on human dendritic cells.

OX40 ligand (OX40L), a member of the TNF family, was shown to be capable of signaling both the cells on which it is expressed and those expressing OX40, its cognate receptor. Here we show that OX40L is expressed on dendritic cells (DC), the most efficient APC to prime naive T cells. The expression and the functional activity of OX40L were examined by means of mAbs used to stain or cross-link OX40L on 1) freshly isolated human blood DC (bDC) and 2) monocyte-derived DC at different stages of differentiation.

Abnormal regulation of retinoic acid receptor beta2 expression and compromised allograft rejection in transgenic mice expressing antisense sequences to retinoic acid receptor beta1 and beta3.

Transgenic mice carrying antisense sequences common to the retinoic acid receptors (RAR) beta1 and beta3 were produced to examine roles of RARbeta1 and beta3 in the immune system. There were no significant changes of endogenous RARbeta1/beta3 expression at the mRNA level in T cells, B cells, and macrophages of the transgenic mice (AS-RARbeta1/beta3 mice). However, there was a decrease of RARbeta1/beta3 protein in the T cells, as expected.

Ectopic gene targeting exhibits a bimodal distribution of integration in murine cells, indicating that both intra- and interchromosomal sites are accessible to the targeting vector.

Ectopic gene targeting is an alternative outcome of the gene targeting process in which the targeting vector acquires sequences from the genomic target but proceeds to integrate elsewhere in the genome. Using two-color fluorescent in situ hybridization analysis, we have determined the integration sites of the gene targeting vector with respect to the target locus in a murine fibroblast line (LTA). We found that for ectopic gene targeting the distribution of integration sites was bimodal, being either within 3 Mb of the target or on chromosomes distinct from the chromosome carrying the target locus.

Somatic mosaicism for Friedreich's ataxia GAA triplet repeat expansions in the central nervous system.

Most patients with Friedreich's ataxia (FRDA) carry expanded GAA repeats in both homologues of the frataxin gene on chromosome 9. We determined the size of the GAA repeats in autopsied samples from the CNS of six FRDA patients. We observed heterogeneity of repeat sizes in different CNS regions, indicative of extensive mitotic instability.

The Friedreich ataxia GAA triplet repeat: premutation and normal alleles.

The most common mutation causing Friedreich ataxia (FRDA), an autosomal recessive neurodegenerative disease, is the hyperexpansion of a polymorphic GAA triplet repeat localized within an Alu sequence (GAA-Alu) in the first intron of the frataxin (X25) gene. GAA-Alu belongs to the AluSx subfamily and contains several polymorphisms in strong linkage disequilibrium either with a subgroup of normal alleles, or with hyperexpanded FRDA-associated alleles. GAA repeat sizes in 300 normal chromosomes (97 from carriers and 203 from controls) were distributed in two separate groups: 83% of them contained between six and 10 triplets (small normal alleles), while the remaining 17% had more than 12 triplets, up to 36 (large normal alleles).

Phenotypic variability in Friedreich ataxia: role of the associated GAA triplet repeat expansion.

We studied genotype-phenotype correlations in a group of 100 patients with typical Friedreich ataxia (FRDA), and in three groups of patients with atypical clinical presentations, including 44 Acadian FRDA, 8 late-onset FRDA (LOFA), and 6 FRDA with retained reflexes (FARR). All patients, except 3 with typical FRDA, carried two copies of the FRDA-associated GAA triplet repeat expansion. Overall, the phenotypic spectrum of FRDA appeared to be wider than defined by the currently used diagnostic criteria.

Differential behavior of curved DNA upon untwisting.

We have synthesized DNA segments with different handedness, twisting and radii of curvature, and have analyzed the effect of untwisting on them. The results indicate that the dynamic behavior of curved DNA upon untwisting is strongly determined by the initial sequence-dependent DNA trajectory. In particular, DNA with the same radii but with opposite handedness of superhelix twisting can show very different conformational responses to ethidium bromide untwisting.

Purification of intact nuclear lamina and identification of novel laminlike proteins in Raji, a cell line devoid of lamins A and C.

Research on the structure of the nuclear lamina and the nuclear matrix of cells devoid of lamins A and C has been hampered by the fact that intact residual nuclear structures are difficult to isolate from such cells. In this paper, we show that some extraction parameters, such as buffer composition and the nature of the detergent used to remove nuclear membranes, are critical for achieving isolation of whole nuclear residual structures from the lymphoblastic cell line Raji, used as a model for cells without lamins A and C. Electron microscopic analysis shows that the nuclear lamina of Raji cells is formed by a network of intermediate-size filaments interrupted with circular discontinuities.

Frataxin shows developmentally regulated tissue-specific expression in the mouse embryo.

Friedreich ataxia (FRDA) is an autosomal recessive degenerative disease caused either by an intronic GAA triplet repeat expansion that suppresses the expression of the frataxin gene on chromosome 9q13, or, rarely, by point mutations in the frataxin gene. We investigated the expression of the mouse frataxin homologue during embryonic development by Northern blot analysis and RNA in situ hybridization. Very faint expression could be detected from E10.

Discordance in p53 mutations when comparing ascites and solid tumors from patients with serous ovarian cancer.

We performed a mutational analysis of the p53 gene in matched samples of solid tumors and ascites from patients with ovarian cancer using the single-strand conformation polymorphism technique on exons 5-9 of the p53 gene on fresh and cultured material. We observed a discordance in the pattern of p53 mutations between the ascites and their solid tumor counterpart. In two cases, cancer cells from ascites carried a p53 mutation and the corresponding solid tumor cells retained the wild-type allele, while the opposite pattern was observed in two other patients samples.

Polyomavirus large T antigen zinc finger is not required for efficient cellular immortalization of primary rat embryo fibroblasts.

The polyomavirus large T antigen contains a zinc finger domain required for the formation of hexamers involved in viral DNA replication. Since mutations within the zinc finger domains of transforming proteins like SV40 large T antigen and human papilloma virus E7 protein generally decrease their overall transforming activity, we have examined the ability of a mutant polyomavirus large T antigen that harbors a deletion in sequences within the zinc finger motif to immortalize primary rat embryo fibroblasts. In contrast to result obtained with SV40 large T antigen and the human papilloma virus E7 protein we show that deletion of the entire zinc finger motif enhances the immortalization efficiency of this mutant T antigen.