Cooperative interaction of Angiopoietin-like proteins 1 and 2 in zebrafish vascular development

Angiopoietin-like protein (Angptl) 1 and Angptl2, which are considered orphan ligands, are highly homologous, particularly in the fibrinogen-like domain containing the putative receptor binding site. This similarity suggests potentially cooperative functions between the two proteins. In this report, the function of Angptl1 and Angptl2 is analyzed by using morpholino antisense technology in zebrafish. Knockdown of both Angptl1 and Angptl2 produced severe vascular defects due to increased apoptosis of endothelial cells at the sprouting stage. In vitro studies showed that Angptl1 and Angptl2 have antiapoptotic activities through the phosphatidylinositol 3-kinase/Akt pathway, and coinjection of constitutively active Akt/protein kinase B mRNA rescued impaired vascular development seen in double knockdown embryos. These results provide a physiological demonstration of the cooperative interaction of Angptl1 and Angptl2 in endothelial cells through phosphatidylinositol 3-kinase/Akt mediated antiapoptotic activities.     

Regulation of hematopoietic stem cells by the niche

The quiescent state in the cell cycle is thought to be indispensable for the maintenance of hematopoietic stem cells (HSCs). Interaction of HSCs with their particular microenvironments, known as niches, is critical for maintaining the stem cell properties of HSCs, including cell adhesion, survival, and cell division. Hematopoietic stem cells balance quiescence and cell division in the stem cell niche and also maintain the potential for long-term hematopoiesis. We have recently reported that HSCs expressing the receptor tyrosine kinase Tie2 are in the G0 phase and anti-apoptotic, and comprise a side-population (SP) of HSCs, which contacts osteoblasts (OBs), the source of the angiopoietin-1 (Ang-1) ligand for Tie2 in the bone marrow (BM) niche. Tie2/Ang-1 signaling occurs in interactions between HSCs and niche cells. The interaction of Tie2 with Ang-1 in vitro induces tight adhesion of HSCs to stromal cells and is sufficient to maintain the long-term blood-repopulating (LTR) activity of HSCs in vivo by preventing cell division. In addition, Ang-1 enhances the ability of HSCs to become quiescent and induces their adhesion to the bone surface in vivo, resulting in protection of the HSC compartment from stresses suppressing hematopoiesis. These data suggest that the Tie2/Ang-1 signaling pathway plays a critical role in the maintenance of HSCs in the adult BM niche. Ang-1 produced by OBs activates Tie2 on HSCs and promotes tight adhesion of HSCs to the niche, resulting in quiescence and enhanced survival of HSCs.     

p38 MAPK-mediated signals are required for inducing osteoclast differentiation but not for osteoclast function

Receptor activator of nuclear factor-kappaB ligand (RANKL)-induced signals play critical roles in osteoclast differentiation and function. SB203580, an inhibitor of p38 MAPK, blocked osteoclast formation induced by 1alpha,25-dihydroxyvitamin D(3) and prostaglandin E(2) in cocultures of mouse osteoblasts and bone marrow cells. Nevertheless, SB203580 showed no inhibitory effect on RANKL expression in osteoblasts treated with 1alpha,25-dihydroxyvitamin D(3) and prostaglandin E(2). RANKL-induced osteoclastogenesis in bone marrow cultures was inhibited by SB203580, suggesting a direct effect of SB203580 on osteoclast precursors, but not on osteoblasts, in osteoclast differentiation. However, SB203580 inhibited neither the survival nor dentine-resorption activity of osteoclasts induced by RANKL. Lipopolysaccharide (LPS), IL-1, and TNFalpha all stimulated the survival of osteoclasts, which was not inhibited by SB203580. Phosphorylation of p38 MAPK was induced by RANKL, IL-1, TNFalpha, and LPS in osteoclast precursors but not in osteoclasts. LPS stimulated phosphorylation of MAPK kinase 3/6 and ATF2, upstream and downstream signals of p38 MAPK, respectively, in osteoclast precursors but not in osteoclasts. Nevertheless, LPS induced degradation of IkappaB and phosphorylation of ERK in osteoclasts as well as in osteoclast precursors. These results suggest that osteoclast function is induced through a mechanism independent of p38 MAPK-mediated signaling.     

An adherent condition is required for formation of multinuclear osteoclasts in the presence of macrophage colony-stimulating factor and receptor activator of nuclear factor kappa B ligand

Identification of receptor activator of nuclear factor-kappaB (RANK) and RANK-ligand (RANKL) has provided new insights into the osteoclast differentiation pathway. Osteoclast precursor cells were isolated using monoclonal antibodies against c-Fms and RANK, and the effect of adherence on the in vitro differentiation and proliferation of these cells was examined in 2 different types of stromal-cell-free culture systems: a semisolid culture medium (a nonadherent system) and a liquid culture medium (an adherent system). Osteoclast precursor cells were not able to differentiate into mature osteoclasts efficiently in the semisolid culture system. Trimerized RANKL enhanced osteoclast differentiation in semisolid cultures, but not to the extent seen when cells were allowed to adhere to plastic. Initial precursor cells were capable of differentiating into macrophages or osteoclasts. Once these cells were transferred to adherent conditions, striking differentiation was induced. Multinuclear cells were observed even after they had displayed phagocytic activity, which suggests that cell adhesion plays an important role in the differentiation of osteoclast precursor cells. Integrins, especially the arginine-glycine-aspartic acid (RGD)-recognizing integrins alpha(v) and beta(3), were needed for osteoclast-committed precursor cells to proliferate in order to form multinuclear osteoclasts, and the increase in cell density affected the formation of multinuclear cells. A model of osteoclast differentiation with 2 stages of precursor development is proposed: (1) a first stage, in which precursor cells are bipotential and capable of anchorage-independent growth, and (2) a second stage, in which the further proliferation and differentiation of osteoclast-committed precursor cells is anchorage-dependent. (Blood. 2000;96:4335-4343)     

A case of bronchial infection of Wangiella dermatitidis]

A 81-year-old woman was admitted to our hospital because of bloody sputum. Chest radiograph showed an enhanced right pulmonary hilum shadow. Computed tomography (CT) revealed localized bronchiectasis of the right lower lung and a nodule protruding into the bronchus. A parenchymal shadow was also seen distal to the nodule. Transbronchial biopsy revealed a cluster of yeast-like fungi and the bronchial lavage culture showed several olive-black colored colonies on Sabouraud agar. Before culture, we empirically administered fluconazole (400 mg/day) on the assumption of candida infection based on the yeast like microscopic findings, however that was not appropriate. Substitution by itraconazole (200 mg/day) made a slight improvement of the shadow on CT. Later polymerase chain reaction of specimens taken by TBLB identified the olive-black fungus as Wangiella dermatitidis. W. dermatitidis is a dematicious fungus sometimes causing tinea nigra or subcutaneous infection. In compromised patients, it causes phaeohyphomycosis especially in the central nerve system. In cystic fibrosis patients, this fungus is recognized to colonize the respiratory tract and rarely causes pneumonia. This case had no previous immunosuppressing disease, except for localized bronchiectasis which was found by CT on admission. We think this is a very rare W. dermatitidis infection case showing a nodular lesion in an immunocompetent patient.     

Aerobic fitness effects in fibromyalgia

OBJECTIVE: To compare 2 exercise modalities, aerobic fitness training and stretching exercises, in patients with fibromyalgia (FM) in relation to function, pain, quality of life, depression, and anxiety, and to correlate the cardiorespiratory fitness gain with symptom improvement. METHODS: Seventy-six women with FM between 18 and 60 years old were randomized to either an aerobic program or stretching program, for 20 weeks. They were evaluated at the beginning of the program and after 10 and 20 weeks in relation to the improvement of aerobic fitness, flexibility, function, Fibromyalgia Impact Questionnaire (FIQ), Short-form Health Survey (SF-36), and depression and anxiety levels. Ventilatory anaerobic threshold (VT) and maximum oxygen uptake (VO2max) were determined by expired gas analyses. RESULTS: Aerobic exercise was superior to stretching in relation to VO2 max, VT, function, depression, pain, and the emotional aspects and mental health domains of SF-36. Patients in the stretching group showed no improvement in depression, "role emotional," and "mental health." No association was noted between improvement in aerobic fitness as measured by VT and the improvement of pain, function, or scores in FIQ and SF-36. CONCLUSION: Our results confirm that aerobic exercise is beneficial to patients with FM, but the cardiorespiratory fitness gain is not related to improvement of FM symptoms.     

The role of prostaglandin E receptor subtypes (EP1, EP2, EP3, and EP4) in bone resorption: an analysis using specific agonists for the respective EPs

PGE2 functions as a potent stimulator of bone resorption. The action of PGE2 is thought to be mediated by some PGE receptor subtypes present in osteoblastic cells. In this study, we examined the involvement of PGE receptor subtypes, EP1, EP2, EP3, and EP4, in PGE2-induced bone resorption using specific agonists for the respective EPs. In mouse calvaria cultures, EP4 agonist markedly stimulated bone resorption, but its maximal stimulation was less than that induced by PGE2. EP2 agonist also stimulated bone resorption, but only slightly. EP1 and EP3 agonists did not stimulate it at all. RT-PCR showed that osteoblastic cells isolated from newborn mouse calvaria expressed all of the EPs messenger RNA (mRNA). Both EP2 agonist and EP4 agonist induced cAMP production and the expression of osteoclast differentiation factor (ODF) mRNA in osteoblastic cells. Simultaneous addition of EP2 and EP4 agonists cooperatively induced cAMP production and ODF mRNA expression. In mouse bone marrow cultures, EP2 and EP4 agonists moderately induced osteoclast formation, but the simultaneous addition of the two agonists cooperatively induced it, similar to that by PGE2. In calvaria culture from EP4 knockout mice, a marked reduction in bone resorption to PGE2 was found. In EP4 knockout mice, EP4 agonist failed to induce bone resorption, but EP2 agonist slightly, but significantly, induced bone resorption. These findings suggest that PGE2 stimulates bone resorption by a mechanism involving cAMP and ODF, which is mediated mainly by EP4 and partially by EP2.     

MALIGNANT FIBROUS HISTIOCYTOMA OF BONE ASSOCIATED WITH FOCAL HEMANGIOPERICYTOMATOUS PATTERN

A case of malignant fibrous histiocytoma of the tibia of a 49-year-old Japanese farmer was presented. The patient was diagnosed as malignant hemangiopericytoma by biopsy, wheseas the amputated material showed a marked pleomorphism representing features of malignant fibrous histiocytoma. Ultrastructurally, undifferentiated mesenchymal cells, intermediate cells between the undifferentiated mesenchymal cells and fibroblastic cells, fibroblastic cells and histiocytoid cells including bizarre giant cells were confirmed in a broad modulating spectrum. The hemangiopericytomatous lesion was predominated by intermediate cells, the ultrastructure of which bore a close resemblance to that of pericytes, and was regarded to be resulted from a differentiation of undifferentiated mesenchymal cells towards the pericyte.     

Up-regulation of FSHR expression during gonadal sex determination in the frog Rana rugosa

In vertebrates, gonadal production of steroid hormones is regulated by follicle-stimulating hormone (FSH) and luteinizing hormone (LH) via their receptors designated FSHR and LHR, respectively. We have shown recently that steroid hormones are synthesized in the differentiating gonad of tadpoles during sex determination in the frog Rana rugosa. To elucidate the role of gonadotropins (GTHs) and their receptors in the production of gonadal steroid hormones during sex determination, we isolated the full-length FSHβ, LHβ, FSHR and LHR cDNAs from R. rugosa and determined gonadal expression of FSHR (FSH receptor) and LHR (LH receptor) as well as brain expression of FSHβ and LHβ during sex determination in this species. The molecular structures of these four glycoproteins are conserved among different classes of vertebrates. FSHβ expression was observed at similar levels in the whole brain (including the pituitary) of tadpoles, but it showed no sexual dimorphism during gonadal sex determination. By contrast, LHβ mRNA was undetectable in the whole brain of tadpoles. FSHβ-immunopositive cells were observed in the pituitary of female tadpoles with a differentiating gonad. Furthermore, FSHR expression was significantly higher in the gonad of female tadpoles during sex determination than in that of males, whereas LHR was expressed at similar levels in males and females. The results collectively suggest that FSHR, probably in conjunction with FSH, is involved in the steroid-hormone production during female-sex determination in R. rugosa.