Joint homeostasis, restoration, and remodeling in osteoarthritis

Osteoarthritis is the major cause of joint failure. The outcome of the disease process is determined by complex interactions between cells and molecules steering homeostasis, destruction, restoration, and remodeling. The articular cartilage has a limited restoration and repair capacity. Genetic studies in humans and the development of mouse models have identified the role of signaling pathways that are important for skeletal development in the postnatal biology and pathology of articular cartilage. These include bone morphogenetic protein, transforming growth factor beta, fibroblast growth factor, wingless-type signaling, and their respective antagonists such as noggin and frizzled related protein. The synovium is prone to inflammation and emerging evidence suggests that innate and adaptive immune responses are important. Bone and cartilage form a biomechanical unit; stiffer bones might impair cartilage homeostasis. The biology of frizzled related protein provides a basis for the hypothesized inverse relationship between osteoarthritis and osteoporosis.     

Overlapping phenotypes of multidrug resistance among panels of human cancer-cell lines

In addition to P-glycoprotein (Pgp), 2 proteins related to multidrug resistance (MDR) have recently been described. The Multidrug-Resistance-associated protein (MRP) is one of the ATP-binding-cassette (ABC) transporters. The Lung-Resistance Protein (LRP) is the major component of human vaults, which are newly described cellular organelles and thought to mediate intracellular transport processes. Using immunocytochemical methods, we have examined the expression of MRP and LRP among panels of human cancer-cell lines not selected for drug resistance which have been previously characterized for expression of Pgp, and in vitro response to a variety of anti-cancer drugs. Expression of MRP and LRP was observed in 47/55 (87%) and 46/59 (78%) cell lines, respectively. Statistically significant correlations were observed between expression of each of these 3 proteins and in vitro sensitivity to at least one drug classically associated with MDR. LRP showed the greatest individual predictive value, which also applied to several non-classical MDR drugs. Co-expression of 2–3 MDR-related proteins was observed in 64% of the lines and was, in general, associated with high relative levels of drug resistance. Previously identified “classic” MDR lines as well as “pan-resistant” lines concurrently expressed all 3 MDR-related proteins. Some highly drug-resistant cell lines without detectable MDRI/Pgp were found to express relatively high levels of MRP and LRP. The high prevalence of MRP and LRP expression observed in this large set of cell lines, which have not been subjected to laboratory drug selection, suggests that MDR mechanisms associated with these proteins may be widespread in human malignancies. Moreover, the overlapping of these more recently recognized MDR phenotypes with Pgp-type MDR results in a complex phenotype, the understanding of which may be of importance in the development of new drugs and design of clinical treatment protocols, particularly those seeking to employ strategies to reverse the MDR phenotype. © 1996 Wiley-Liss, Inc.     

Analysis of IgG reactivity against human papillomavirus type-16 E7 in patients with cervical intraepithelial neoplasm indicates an association with clearance of viral infection: results of a prospective study

IgG reactivity against the immunodominant region aa6-35 of Human Papillomavirus (HPV) type-16 E7 was determined in a peptide-based ELISA in a cohort study of women with initial mild to moderate cervical dyskaryosis. On the basis of HPV DNA patterns, as determined by PCR in cervical smears prior to IgG testing, HPV-16-positive patients were grouped as having either a cleared, a fluctuating, or a persistent HPV-16 infection. In a cross-sectional study at the start of serological follow-up, positive IgG reactivities were found more often in the total group of HPV-16-positive patients (20.0%) than in patients consistently typed as HPV-negative over a period of at least 12 months prior to testing (3.1%, p < 0.04). The highest proportion of positive responders was found in patients with a cleared HPV-16 infection (29.4%). Also, IgG reactivities found in HPV-16 clearance patients were significantly higher than in patients with a persistent infection (p < 0.008). In a subsequent longitudinal study over a period of up to 27 months, consistently positive reactivities were observed in patients with cleared viral infections who showed seroreactivity in the cross-sectional study, while mostly negative reactivities were found in patients with viral persistence. HPV-16 E7-specific IgG subclass responses were determined in a selection of 19 CIN and 11 HPV- 16-positive cervical carcinoma (CeCa) patients with positive E7-specific IgG responses. IgG₂ was predominant in the CIN patients, suggesting the presence of IFNγ (Th1) at the site of HPV infection. In the CeCa patients IgG₁ and IgG₂ were produced equally, possibly indicating a rise in Th2 cytokines. Our data suggest that HPV-16 E7 IgG reactivity in a subset of CIN patients with viral clearance may result from successful Th1 responses. © 1996 Wiley-Liss, Inc.     

The association of cortical dysplasia and anterior horn arthrogryposis: a case report

We describe a 21-year-old woman with neurogenic congenital contractures (arthrogryposis) of the lower limbs, normal intelligence, hyper-reflexia and partial epilepsy. MRI revealed bilateral opercular (perisylvian) cortical dysplasia with infolding of cerebral cortex, a focal neuroblast migrational disorder. This type of migrational disorder is known to have a prenatal onset after the 20th fetal week, whereas the anterior horn cell degeneration responsible of neurogenic arthrogryposis originates at 12–14 weeks of gestation. A prenatal viral infection along the neural axis during both these gestational periods or a genetic defect could be responsible for both lesions in this case.     

The Validation of the Finite Difference Method and Reciprocity for Solving the Inverse Problem in EEG Dipole Source Analysis

The performance of the finite difference reciprocity method (FDRM) to solve the inverse problem in EEG dipole source analysis is investigated in the analytically solvable three-shell spherical head model for a large set of test dipoles. The location error for a grid with 2 mm and 3 mm node spacing is in general, not larger than twice the internode distance, hence 4 mm and 6 mm, respectively. Increasing the number of scalp electrodes from 27 to 44 only marginally improves the location error. The orientation error is always smaller than 4° for all the test dipoles considered. We have also compared the sensitivity to noise using FDRM in EEG dipole source analysis with the sensitivity to noise using the analytical expression for the forward problem. FDRM is not more sensitive to noise than the method using the analytical expression.     

Specific CD8+ T‐lymphocytes control dissemination of measles virus

Measles continues to be an important cause of childhood mortality in developing countries. Measles virus (MV) is lymphotropic and infects high percentages of B‐ and T‐lymphocytes in lymphoid tissues. Cellular immunity is considered crucial for viral clearance; however, MV‐specific T‐lymphocytes generated during primary infection also constitute a potential target for MV infection. We therefore aimed to identify T‐lymphocyte subsets that can clear MV infection without becoming infected. To this end, we infected human EBV transformed B‐lymphoblastic cell lines (B‐LCL) with a recombinant MV strain expressing enhanced GFP, and co‐cultured these with non‐infected B‐LCL resulting in rapid viral spread. MV‐specific CD8⁺ T‐cell clones efficiently suppressed MV dissemination in autologous and HLA‐matched, but not in HLA‐mismatched B‐LCL. In contrast, CD4⁺ T‐cell clones could not control MV dissemination but became a target for MV infection themselves. Furthermore, PBMC collected 6–9 months after acute measles and stimulated with autologous MV‐infected B‐LCL also efficiently suppressed MV dissemination; this was mediated by the fraction containing CD8⁺ T‐lymphocytes. In conclusion, we have developed a powerful tool to study cellular immunity against measles, and demonstrate that control of MV dissemination is mediated by virus‐specific CD8⁺ rather than by CD4⁺ T‐lymphocytes.     

Characterization, expression and complex formation of the murine Fanconi anaemia gene product Fancg

BACKGROUND: Fanconi anaemia (FA) is an autosomal recessive chromosomal instability disorder. Six distinct FA disease genes have been identified, the products of which function in an integrated pathway that is thought to support a nuclear caretaker function. Comparison of FA gene characteristics in different species may help to unravel the molecular function of the FA pathway. RESULTS: We have cloned the murine homologue of the Fanconi anaemia complementation group G gene, FANCG/XRCC9. The murine Fancg protein shows an 83% similarity to the human protein sequence, and has a predicted molecular weight of 68.5 kDa. Expression of mouse Fancg in human FA-G lymphoblasts fully corrects their cross-linker hypersensitivity. At mRNA and protein levels we detected the co-expression of Fancg and Fanca in murine tissues. In addition, mouse Fancg and Fanca proteins co-purify by immunoprecipitation. Upon transfection into Fanca-deficient mouse embryonic fibroblasts EGFP-Fancg chimeric protein was detectable in the nucleus. CONCLUSIONS: We identified a murine cDNA, Fancg, which cross-complements the cellular defect of human FA-G cells and thus represents a true homologue of human FANCG. Spleen, thymus and testis showed the highest Fancg expression levels. Although Fancg and Fanca are able to form a complex, this interaction is not required for Fancg to accumulate in the nuclear compartment.