Changes of isoagglutinin titres after ABO-incompatible allogeneic stem cell transplantation

We investigated the changes in isoagglutinin titres in 62 patients who underwent ABO-incompatible allogeneic stem cell transplantation. After major [and/or (+/-) minor] ABO-incompatible transplantation, recipient-derived isoagglutinins against donor-type red blood cells (RBCs) disappeared more rapidly in unrelated recipients (P = 0.006) and in patients with acute graft-versus-host disease (GVHD, P = 0.025) than in sibling recipients and in patients without acute GVHD respectively. Pure red cell aplasia (PRCA) developed in 10 out of 35 evaluable patients who underwent major (+/- minor) ABO-incompatible transplantation, and the post-transplant increase of isoagglutinin titres was a significant predictor for the occurrence of PRCA. In five out of 36 patients who underwent minor (and/or (+/-) major) ABO-incompatible transplantation, donor-derived isoagglutinins against recipient RBCs were detectable without clinically overt haemolysis. Isoagglutinin titres against ABO antigens absent both on recipient and donor RBCs decreased during the early post-transplant period then rose subsequently in 24 out of 29 patients at (median) d 59 post transplant. Our study showed that changes in isoagglutinin titres might have clinical implications in the occurrence of immunohaematological complications such as PRCA or immune-mediated haemolysis, and might reflect immunohaematological reconstitution after transplantation. Furthermore, our data regarding time to disappearance of recipient-derived isoagglutinins against donor-type RBCs after major ABO-incompatible transplantation suggest the presence of a graft-versus-plasma cell effect.     

Biocompatibility and charge injection property of iridium film formed by ion beam assisted deposition

Iridium thin film formed by electron-beam evaporation with simultaneous bombardment of Ar ion beam was evaluated for a stimulating neural electrode. The electrochemical behavior of as-deposited Ir film on Ni-Ti sample was almost identical to bulk Ir by producing much higher open-circuit corrosion potential and much lower anodic current density than the uncoated Ni-Ti in both 1N sulfuric acid and saline solution. The charge injection capability of Ir film was compared with that of Pt electrode currently used mostly as a stimulating neural electrode. The charge density of Pt was small and unchanged with increasing number of activating cycles in 0.1M H(2)SO(4), whilst the Ir film continuously produced increases in charge density. The charge injection density of Ir film in physiological solution was higher for the more activated sample under the identical stimulating condition. Attachment and proliferation with PC12 cells on Ir-coated CP Ti without applying electrical stimulation was similar to the polished CP Ti. A network of neurons and extending axons were formed on Ir film.     

Cloning and characterization of cDNAs for two distinct tumor necrosis factor receptor superfamily genes from Japanese flounder Paralichthys olivaceus

Tumor necrosis factor receptor (TNFR) superfamily regulates diverse biologic functions, including cell proliferation, differentiation, and survival, in addition to providing costimulatory signals for programmed cell death or apoptosis. In this study, cDNA fragments for two distinct TNFR homologues were obtained from a Japanese flounder, Paralichthys olivaceus, cDNA library. Full-length cDNAs of TNFR-1 and TNFR-2 homologues were obtained by using these cDNA fragments as probes. The cDNA for the Japanese flounder TNFR-1 homologue predicts a peptide of 395 amino acids that is 35% identical to the extracellular region of mouse TNFR-1, whereas the cDNA of the Japanese flounder TNFR-2 homologue predicts a peptide of 483 amino acids that is 40% identical to the extracellular region of human TNFR-2. The cytoplasmic domain contains a sequence that has the consensus motif of the death domain of the Japanese flounder TNFR-1 homologue. In a healthy fish, the mRNAs of both TNFR homologues were predominantly expressed in leukocytes, kidney, gill, and spleen. Expression of the Japanese flounder TNFR-1 homologue was induced in peripheral blood lymphocytes (PBLs) after stimulation with LPS (500 microg/ml) for 1 h, and TNFR-2 homologue was strongly induced in PBLs after stimulation with Con A (50 microg/ml) and PMA (0.35 microg/ml) for 3 h. The different expression patterns of the two distinct TNFR homologues may be critical in determining whether binding with TNF-alpha or TNF-beta have activating, proliferative, or apoptotic effects on target cells.     

Chromosomal instability in osteosarcoma and its association with centrosome abnormalities

The mechanism that generates the extreme aneuploidy that characterizes osteosarcoma (OS) is poorly understood. In this study, interphase fluorescence in situ hybridization (FISH) analysis was used to enumerate cell-to-cell variation of several different chromosomes. We also investigated whether there was an association between TP53 mutation and centrosome aberrations in the generation of chromosomal aneuploidy in OS in four OS cell lines (HOS, SAOS2, U2OS, and MG63) and in a subset of seven tumors. Our analysis showed that there was a wide range of numerical changes affecting multiple chromosomes in OS cell lines and tumors. These data suggest that chromosomal instability (CIN) could be responsible for the extensive aneuploidy associated with this tumor. The results also showed an increased frequency of atypical mitotic figures in three OS cell lines with defective TP53, function and significantly, a more marked CIN phenotype was present in these lines. Furthermore, numerical aberrations of centrosomes were also present in these three OS cell lines with TP53 mutations. In two of three OS patients' tumors there was a large increase in the percentage of abnormal centrosome numbers. We conclude that CIN is a consistent feature of OS and that an intrinsic disturbance of the chromosomal segregation mechanisms is likely associated with centrosome aberrations.     

Modifier genes and heart failure

Recent progress in genomic applications have led to a better understanding of the relationship between genetic background and cardiovascular diseases such as heart failure. A considerable component of the variability in heart failure outcome is due to modifier genes, i.e. genes that are not involve in the genesis of a disease but modify the severity of the phenotypic expression once the disease has developed. The strategy most commonly used to identify modifier genes is based on association studies between the severity of the phenotype of the disease (morbidity and/or mortality) and the sequence variation(s) of selected candidate gene(s). This strategy has showed that several polymorphisms of the beta1 and beta2 adrenergic receptors genes and the angiotensin converting enzyme gene are correlated to the prognosis of patients with heart failure. Recently, we have applied an experimental strategy, known as genome mapping, for the identification of heart failure modifier genes. Genome mapping has previously been used with success to identify the genes involved in the development of both monogenic and multifactorial diseases. We have showed that the prognosis of heart failure mice, induced through overexpressing calsequestrin, is linked to 2 Quantitative Trait Loci (QTL) localized on chromosome 2 and 3. Using both strategies (candidate gene and genome mapping) should allow us to identify a number of modifier genes that may provide a more rational approach to identify patients at risk for disease and response to therapy.     

Role of glucocorticoids in the regulation of pituitary somatostatin receptor subtype (sst1-sst5) mRNA levels: evidence for direct and somatostatin-mediated effects

Glucocorticoids can differentially regulate somatostatin (SRIH) receptor subtype expression depending on the duration of treatment, dose used and tissue type examined. In order to determine if glucocorticoids are critical regulators of pituitary SRIH receptor synthesis in vivo, we examined the effect of adrenalectomy (ADX), with and without dexamethasone (DEX; 200 microg/day for 8 days) treatment, on the relative expression levels of the SRIH receptor subtypes, sst1-sst5, by multiplex RT-PCR. ADX increased pituitary sst2 mRNA levels, but did not significantly alter mRNA levels of the other SRIH receptor subtypes. These findings indicate that pituitary sst2 synthesis is normally under inhibitory control of endogenous glucocorticoids. High-dose DEX resulted in a decrease in sst1-sst4 mRNA and an increase in sst5 mRNA, independent of adrenal status. DEX also decreased sst2, sst3 and sst4 mRNA levels and increased sst5 mRNA levels by short-term in vitro application (10 nM, 4 h) in primary rat pituitary cell cultures, indicating DEX regulation of sst2-sst5 in vivo is at least in part due to a direct action at the level of the pituitary. However, the inhibitory actions of DEX on sst1 mRNA levels observed in vivo were not consistently replicated in vitro. In order to determine if the somatotrope population of the pituitary would display a similar response to DEX, fluorescent-activated cell sorting was used to obtain somatotrope-enriched cultures (>95% growth hormone immunopositive cells). DEX treatment (10 nM, 4 h) of somatotropes decreased sst2 and sst3, but did not alter sst5 mRNA levels. These results indicate that the effects of DEX on sst5 mRNA levels observed in unsorted pituitary cell cultures might be due to changes in sst5 expression in pituitary cell types other than somatotropes. Since excess glucocorticoids are thought to enhance SRIH tone, we also tested if ligand activation of SRIH receptor subtypes in vitro could mimic any of the actions of DEX on SRIH receptor mRNA levels observed in vivo. To this end, unsorted pituitary cell cultures and somatotrope-enriched cultures were treated with SRIH (1 and 100 nM) for 4 h. SRIH increased sst3 and sst5 mRNA levels, in both culture systems. These results suggest that the DEX-induced increase in endogenous SRIH tone may contribute to enhanced sst5 mRNA levels observed in vivo. However, the stimulatory actions of SRIH on sst3 mRNA levels observed in vitro might be overridden by direct inhibitory actions of DEX.