Spermiogenesis in Caenorhabditis elegans: An Excellent Model to Explore the Molecular Basis for Sperm Activation.

C. elegans spermiogenesis converts non-motile spermatids into motile, fertilization-competent spermatozoa. Two major events include the building of a pseudopod required for motility and fusion of membranous organelles (MOs)-intracellular secretory vesicles-with the spermatid plasma membrane required for the proper distribution of sperm molecules in mature spermatozoa. The mouse sperm acrosome reaction-a sperm activation event occurring during capacitation-is similar to MO fusion in terms of cytological features and biological significance. Moreover, C. elegans fer-1 and mouse Fer1l5, both encoding members of the ferlin family, are indispensable for MO fusion and acrosome reaction, respectively. Genetics-based studies have identified many C. elegans genes involved in spermiogenesis pathways; however, it is unclear whether mouse orthologs of these genes are involved in the acrosome reaction. One significant advantage of using C. elegans for studying sperm activation is the availability of in vitro spermiogenesis, which enables combining pharmacology and genetics for the assay. If certain drugs can activate both C. elegans and mouse spermatozoa, these drugs would be useful probes to explore the mechanism underlying sperm activation in these two species. By analyzing C. elegans mutants whose spermatids are insensitive to the drugs, genes functionally relevant to the drugs' effects can be identified.

Measurement of sialic acid content is insufficient to assess bioactivity of recombinant human erythropoietin.

Assessment of biological potency and its comparison with clinical effects are important in the quality control of therapeutic glycoproteins. Animal models are usually used for evaluating bioactivity of these compounds. However, alternative methods are required to simplify the bioassay and avoid ethical issues associated with animal studies. Negatively charged sialic acid residues are known to be critical for in vivo bioactivity of recombinant human erythropoietin (rhEPO). In this study, we used capillary zone electrophoresis, a charge-based separation method, to estimate the sialic acid content for predicting in vivo bioactivity of rhEPO. In vivo bioactivities of rhEPO subfractions were measured and compared with sialylation levels. The results obtained indicated that in vivo bioactivity of rhEPO is not simply correlated with the sialylation level, which suggests that it is difficult to predict biological potency from the sialic acid content alone. N-Glycan moieties as well as sialic acid residues may have a significant impact on in vivo bioactivity of rhEPO.

Clinical manifestations and analyses of the cytotoxic T-lymphocyte associated-4 gene in two Japanese families with systemic lupus erythematosus.

Although still incompletely understood, the etiology of systemic lupus erythematosus (SLE) is considered to involve both genetic and environmental factors. We encountered two boys with severe SLE from unrelated families and analyzed the gene that encodes cytotoxic T-lymphocyte-associated (CTLA)-4, a protein important in T-cell activation and immune tolerance. Abnormal function of the gene may participate in causation of autoimmune disease, including SLE. In family 1, a boy showed serious cardiovascular complications associated with heart failure, and his mother also had clinically active SLE, including nephritis. A boy in family 2 developed severe renal complications and peripheral vasculitis accompanied by disseminated petechiae in the lower extremities. His paternal grandfather had died from fibrinous pneumonia caused by SLE. They showed high SLE Disease Activity Index (SLEDAI) score. Analysis of the CTLA-4 gene indicated that the boy in family 1 and his mother and the boy in family 2 possess a GG genotype in CTLA-4 exon 1 at +49 together with a 106-bp fragment length of the 3' untranslated region (UTR) in exon 4. No association with disease activity was found for polymorphism of the promoter region in exon 1 at -318 in either family. Disorders of the CTLA-4 gene, especially a GG genotype in exon 1 at +49 and/or 106-bp fragment length of the 3'UTR in exon 4, may be involved in early development of SLE in Japanese children, such as the boys described here.

Role of platelet factor 4-heparin complex antibody (HIT antibody) in the pathogenesis of thrombotic episodes in patients on hemodialysis.

Heparin-induced thrombocytopenia (HIT) is a severe complication in patients on hemodialysis (HD). It has been reported that platelet factor-4 (PF-4)-heparin complex antibody (HIT antibody) plays an important role in the pathogenesis of this serious complication. In the present study, we investigated the role of HIT antibody in the pathogenesis of thrombotic complications including shunt failure, cerebrovascular disease (CVD) and atherosclerosis in patients on dialysis. Plasma concentration of HIT antibody in patients on HD was 0.143+/-0.008 (n=105). This was significantly higher in patients on continuous ambulatory peritoneal dialysis (CAPD: 0.087+/-0.006, p=0.0008, n=22) and in non-dialysis patients (0.113+/-0.011, p=0.0011, n=12). There was a significant negative correlation between HIT antibody and the duration of dialysis. However, no significant correlation was found between HIT antibody and other factors including age, dose of heparin, platelet count and hemoglobin. There was a significant correlation between the number of failed arteriovenous fistula and HIT antibody levels. In addition, in patients with a history of CVD, plasma concentrations of HIT antibody were significantly higher compared with patients without CVD (CVD(+): 0.200+/-0.029 vs. (-): 0.127+/-0.005, p<0.0001). It is possible that genetic factors may also play a role in the expression of HIT antibody. From these data, it appears possible that HIT antibody plays an important role in the pathogenesis of thrombosis in patients on HD. Further studies are needed to clarify the role of HIT antibody in the pathogenesis of thrombotic episodes in these patients.