Hyaluronidases in tissue invasion

Hyaluronidases are broadly distributed enzymes with varying substrate specificities, a wide range of pH optima, and different catalytic mechanisms. They may be used by organisms to invade one another. Hyaluronidases have also been invoked as mechanisms for tumor invasion and metastatic spread. In this review, we will concentrate more on the different kinds of hyaluronidases involved in tissue invasion other than cancer metastasis, present some of the rapidly accumulating new data, and address the paradox that both hyaluronidase as well as its hyaluronan substrate are associated with invasion.     

Kidney morphological changes in relation to long-term renal function and metabolic control in adolescents with IDDM

OBJECTIVE: To investigate the impact of HIV infection on the prevalence, incidence and short-term prognosis of squamous intraepithelial lesions (SIL), in a prospective study with 1-year follow-up. METHODS: Between 1993 and 1995, 271 HIV-positive and 171 HIV-negative women at high risk of HIV infection were recruited, 365 (82.6%) of whom completed the 1-year follow-up. The women underwent a Papanicolaou smear test at inclusion and at 6 and 12 months. Human papillomavirus (HPV) was detected at inclusion by Southern blot and PCR. RESULTS: The SIL prevalence ranged from 7.5% for HIV-negative to 31.3% for HIV-positive women with CD4 cell counts < 500 x 10(6)/l (P < 0.001). Other factors associated independently and significantly with SIL prevalence were HPV-16, 18, 33 and related types, HPV-31, -35, -39 and related types, lifetime number of partners, younger age, past history of SIL and lack of past cervical screening. The SIL incidence ranged from 4.9% in HIV-negative women to 27% in HIV-positive women with CD4 cells < 500 x 10(6)/l (P < 0.001). Progression from low- to high-grade SIL during follow-up was detected in 38.1% of HIV-positive women with CD4 cells < or = 500 x 10(6)/l but in no HIV-negative nor HIV-positive women with CD4 cells > 500 x 10(6)/l. HPV-16, 18, 33 and related types were also associated with higher incidence of SIL and progression from low- to high-grade SIL. CONCLUSION: HIV-induced immunodeficiency is associated with high prevalence, incidence and persistence/progression of SIL. A pejorative influence of HIV infection without marked immunodeficiency is less clear. HIV-positive women with SIL may thus benefit from early treatment when a useful immune response is still present.     

Selective anticoagulation with active site-blocked factor IXA suggests separate roles for intrinsic and extrinsic coagulation pathways in cardiopulmonary bypass

BACKGROUND: Multiple stimuli converge in cardiopulmonary bypass to create a tremendous prothrombotic stimulus. The ideal anticoagulant for cardiopulmonary bypass should selectively target only the intravascular stimuli, thereby eliminating pathologic clotting in the bypass circuit while preserving hemostasis in the thoracic cavity. We propose the inhibition of factor IX as such a targeted anticoagulant strategy. METHODS: We prepared an inhibitor of activated factor IX and applied it to a primate model of cardiopulmonary bypass to confirm the anticoagulant efficacy of activated factor IX in this setting and to assess more subtle markers of thrombin generation, macrophage procoagulant activity, and cellular tissue factor expression. Seven baboons that received activated factor IX (460 microg/kg) and 7 that received heparin (300 IU/kg) and protamine underwent cardiopulmonary bypass for 90 minutes and were followed after the operation for 3 hours. RESULTS: Analysis of plasma factor IX activity demonstrated adequate inhibition (<20%) of factor IX throughout cardiopulmonary bypass. Activated factor IX-treated baboons demonstrated similar circuit patency to heparin-treated baboons but had significantly diminished intraoperative blood loss. Preservation of extravascular hemostasis was further demonstrated in activated factor IX-treated animals by (1) significantly increased levels of thrombin-antithrombin III complex and prothrombin activation peptide (F1+2) without intravascular thrombosis, (2) significantly greater macrophage procoagulant activity in pericardial-derived monocytes, and (3) immunohistochemical evidence of tissue factor expression in pericardial mesothelial cells and macrophages. CONCLUSIONS: Anticoagulation with activated factor IX allows for intravascular anticoagulation with maintenance of extravascular hemostasis. These findings suggest activated factor IX as an agent that not only exemplifies a targeted approach to selective anticoagulation in cardiac surgery but also further characterizes the procoagulant milieu during cardiopulmonary bypass.     

Placental site trophoblastic tumor: human placental lactogen and pregnancy-associated major basic protein as immunohistologic markers

Placental site trophoblastic tumor (PSTT) consists of a neoplastic proliferation of intermediate or extravillous trophoblast (also known as X cells). Pregnancy-associated major basic protein (pMBP) is a marker for placental intermediate trophoblast. We compared the distribution of pMBP and human placental lactogen (hPL) in 24 PSTT and 3 exaggerated placental site (EPS) specimens using two distinct immunohistologic methods. Statistical analyses were used to compare staining intensities in metastatic and nonmetastatic lesions. By immunofluorescence, 77% of the PSTT specimens and 100% of the EPS specimens stained with antibodies to pMBP, and the pMBP was localized in intermediate trophoblast and surrounding extracellular areas. By immunohistochemistry, 78% of the PSTT specimens and 100% of the EPS specimens stained for pMBP with a pattern comparable with that of immunofluorescence. Likewise, by immunohistochemistry, hPL stained 96% of the PSTT specimens and 100% of the EPS specimens. Immunohistochemical staining intensities for pMBP and hPL correlated (r2 = +.24; P = .013), but hPL staining was mainly confined to intermediate trophoblast and was more intense. Anti-pMBP tended to stain metastatic PSTT weakly. Thus, pMBP is a useful marker for intermediate trophoblast tumors and could help distinguish these from other forms of trophoblastic disease.     

Topographical organization in the early postnatal corticopontine projection: a carbocyanine dye and 3-D computer reconstruction study in the rat

We have explored basic rules guiding the early development of topographically organized projections, employing the rat corticopontine projection as a model system. Using anterograde in vivo tracing with 1,1',dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI), we studied the distribution of labelled fibers in the pontine nuclei in relation to cortical site of origin during the first postnatal week. Labelled corticopontine fibers enter the pontine nuclei in distinct, sharply defined zones. The putative terminal fibers typically occupy lamella-like subspaces. Related to changes in cortical site of origin, we describe mediolateral, internal to external, and caudorostral distribution gradients in the pontine nuclei. Fibers originating in the anterolateral cortex occupy an internal central core, while implantations at increasing distance from the anterolateral cortex produce 1) more externally located lamellae, and 2) a caudal to rostral shift in fiber location. Previous investigations have shown that pontocerebellar neurons migrate into the ventral pons in a temporal sequence (Altman and Bayer [1987] J. Comp. Neurol. 257:529). The earliest arriving neurons occupy the central core and later arriving neurons settle in more externally and rostrally located subspaces. We hypothesize that the earliest arriving corticopontine fibers grow into the then only available zone of pontocerebellar neurons (central core), attracted by a diffusible chemotropic cue. Later arriving fibers grow into correspondingly later and more externally and rostrally located contingents of pontocerebellar neurons. Thus, we propose that the topographical organization in the early postnatal corticopontine projection is determined by simple temporal and spatial gradients operative within source (cerebral cortex) and target region (pontine nuclei).     

Solution structure of the C-terminal SH2 domain of the human tyrosine kinase Syk complexed with a phosphotyrosine pentapeptide

BACKGROUND: Recruitment of the intracellular tyrosine kinase Syk to activated immune-response receptors is a critical early step in intracellular signaling. In mast cells, Syk specifically associates with doubly phosphorylated immunoreceptor tyrosine-based activation motifs (ITAMs) that are found within the IgE receptor. The mechanism by which Syk recognizes these motifs is not fully understood. Both Syk SH2 (Src homology 2) domains are required for high-affinity binding to these motifs, but the C-terminal SH2 domain (Syk-C) can function independently and can bind, in isolation, to the tyrosine-phosphorylated IgE receptor in vitro. In order to improve understanding of the cellular function of Syk, we have determined the solution structure of Syk-C complexed with a phosphotyrosine peptide derived from the gamma subunit of the IgE receptor. RESULTS: The Syk-C:peptide structure is compared with liganded structures of both the SH2 domain of Src and the C-terminal SH2 domain of ZAP-70 (the 70 kDa zeta-associated protein). The topologies of these domains are similar, although significant differences occur in the loop regions. In the Syk-C structure, the phosphotyrosine and leucine residues of the peptide ligand interact with pockets on the protein, and the intervening residues are extended. CONCLUSIONS: Syk-C resembles other SH2 domains in its peptide-binding interactions and overall topology, a result that is consistent with its ability to function as an independent SH2 domain in vitro. This result suggests that Syk-C plays a unique role in the intact Syk protein. The determinants of the binding affinity and selectivity of Syk-C may reside in the least-conserved structural elements that comprise the phosphotyrosine- and leucine-binding sites. These structural features can be exploited for the design of Syk-selective SH2 antagonists for the treatment of allergic disorders and asthma.