Trophinin and tastin form a cell adhesion molecule complex that potentially mediates an initial attachment of the blastocyst to uterine epithelial cells at the time of implantation. Trophinin and tastin, however, do not directly bind to each other, suggesting the presence of an intermediary protein. The present study identifies a cytoplasmic protein, named bystin, that directly binds trophinin and tastin. Bystin consists of 306 amino acid residues and is predicted to contain tyrosine, serine, and threonine residues in contexts conforming to motifs for phosphorylation by protein kinases. Database searches revealed a 53% identity of the predicted peptide sequence with the Drosophila bys (mrr) gene. Direct proteinprotein interactions of trophinin, tastin, and bystin analyzed by yeast two-hybrid assays and by in vitro protein binding assays indicated that binding between bystin and trophinin and between bystin and tastin is enhanced when cytokeratin 8 and 18 are present as the third molecule. Immunocytochemistry of bystin showed that bystin colocalizes with trophinin, tastin, and cytokeratins in a human trophoblastic teratocarcinoma cell, HT-H. It is therefore possible that these molecules form a complex and thus are involved in the process of embryo implantation.Embryo implantation is a process that depends on the coordinated development of the embryo and differentiation of the uterus to the receptive state (1-4). A two-way interaction between the blastocyst and uterus is essential for successful implantation and subsequent decidualization (5). In the mouse, the first conspicuous sign of the implantation is an increased endometrial vascular permeability at the site of blastocyst apposition, and this coincides with the initial attachment reaction (3, 6). This attachment is followed by adherence and penetration by trophoblasts cells through the underlying basement membrane and results in proliferation and differentiation of stromal cells into decidual cells. Numerous factors including growth factors (7), cytokines (8), homeotic genes (9), and prostaglandin (10, 11) have been implicated in implantation process. Among these, null mutations of leukemia inhibitory factor and Hoxa-10 genes result in defective implantation (8, 9), and a prostaglandin regulating cyclooxigenase 2 gene knock-out results in multiple failures of female reproductive processes including implantation (10, 11).To understand the molecular mechanisms underlying embryo implantation, identification and characterization of specific molecules responsible for the initial attachment of the embryo and subsequent invasion of the trophoblasts to the uterus are essential. However, such analysis has been difficult because of the absence of appropriate in vitro models for implantation. In this regard two human cell lines, a trophoblastic teratocarcinoma, HT-H (12), and an endometrial adenocarcinoma, SNG-M (13), are noteworthy, because the interaction between these two cell types appears to mimic that of trophoblasts and endometrial epithelial cells parti...

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Cell migration and adhesion during embryonic development are complex processes which likely involve interactions among cell-surface carbohydrates. While considerable work has implicated proteoglycans in a wide range of developmental events, only limited attention has been directed towards understanding the 7role(s) played by the related class of mucin-type O-glycans. The initial step of mammalian mucin-type O-glycosylation is catalyzed by a family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGaNTases). The spatial expression patterns of the messenger RNAs of seven ppGaNTase family members were investigated from gastrulation through organogenesis stages of mouse development. The seven glycosyltransferases were expressed in unique patterns during embryogenesis. ppGaNTase-T1, -T2, -T4, and -T9 were expressed more ubiquitously than ppGaNTase-T3, -T5, and -T7. Organ systems with discrete accumulation patterns of ppGaNTase family members include the gastrointestinal tract (intestine, liver, stomach, submandibular gland), nervous system (brain, eye), lung, bone, yolk sac, and developing craniofacial region. The pattern in the craniofacial region included differential expression by family members in developing mandible, teeth, tongue and discrete regions of the brain including the pons and migratory, differentiating neurons. Additionally, ppGaNTase-T5 accumulates in a subset of mesenchymal cells at the ventral-most portions of the E12.5 maxilla and mandible underlying the dental lamina. The unique spatiotemporal expression of the different ppGaNTase family members during development suggests unique roles for each of these gene products.

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Human IgM monoclonal antibody 16-88, derived from patients immunized with autologous colon carcinoma cells, was derivatized with two different cross-linkers, S-(2-thiopyridyl)-L-cysteine hydrazide (TPCH), which is carbohydrate-directed, and N-succinimidyl-3-(2- pyridyldithio)propionate (SPDP), which is amino group-directed. Two antibody functions, antigen binding and complement activation, were assayed upon derivatization with TPCH and SPDP. TPCH allowed for extensive modification (up to 17 TPCH molecules per antibody) without impairment of antigen binding activity, while this function was significantly compromised upon derivatization with SPDP. Antibody molecules derivatized with 16 SPDP residues showed almost complete loss of their antigen binding function. The complement activating ability of antibody 16-88 was significantly decreased after derivatization with TPCH or SPDP. In the case of SPDP derivatization, this decrease of the complement activating ability is predominantly a consequence of the impaired binding function. Upon conjugation of cobra venom factor (CVF), a nontoxic 137-kDa glycoprotein which is capable of activating the alternative pathway of complement, the antigen binding activity of SPDP-derivatized antibody was further compromised, whereas that of TPCH-derivatized antibody remained unaffected even after attachment of three or four CVF molecules per antibody. In both conjugates CVF retained good functional activity. CVF was slightly more active when attached to SPDP-derivatized antibody, suggesting a better accessibility of amino group-coupled CVF for its interaction with other complement proteins. These results indicate that carbohydrate-directed conjugation compromises the antibody function of complement activation, but allows for the generation of immunoconjugates with unimpaired antigen binding capability.(ABSTRACT TRUNCATED AT 250 WORDS)

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Advocates of drug price restrictions in the U.S. argue that pharmaceutical companies operate in an unregulated market, free to charge whatever price the market will bear. The pharmaceutical industry insists that these large profits are justified for investments toward discovering new life saving medicines. As innovation wanes, marketing costs soar, and drug profits rise, public interest advocates and state leaders are challenging this justification. This article examines current problems associated with the ability to procure affordable medicines, and examines mounting tensions between the federal government and the states, particularly regarding the states' ability to negotiate lower prices with drug manufacturers in light of the recent Medicare changes. It provides a brief survey of efforts underway to secure affordable pharmaceuticals for state's residents, addressing the history and feasibility of using compulsory licensing for producing affordable life-saving drugs with respect to public health, constitutional, eminent domain, and anti-trust issues.