Glucocorticoid in excess suppresses bone formation in vivo and disrupts bone matrix protein synthesis by osteoblasts in vitro. In contrast, transforming growth factor ␤ (TGF-␤) potently enhances bone matrix apposition. The rat TGF-␤ type I receptor gene promoter contains cis-acting elements for transcription factor CBFa1, which increases in parallel with osteoblast differentiation. Here we present molecular data linking these events. We show that previously unexplained effects of glucocorticoid on bone loss may be mediated in part by suppression of CBFa1, with a resultant decrease in the expression and activity of the TGF-␤ type I receptor on matrix-producing bone cells.Glucocorticoid-dependent bone loss by disregulated hormone expression or pharmacologic excess causes clinically significant osteoporosis in approximately 50% of affected individuals. Although changes in calcium absorption and effects on nonskeletal tissues contribute to the disease, striking effects occur directly on osteoblasts and at sites of active skeletal matrix deposition and remodeling (1, 2). A chronic reduction in osteoblast activity without corresponding changes in resorption would uncouple normal bone remodeling and decrease skeletal durability. Important genes targeted by glucocorticoid and molecular mediators for these events remain uncertain.Transforming growth factor ␤ (TGF-␤) 1 enhances bone matrix synthesis and repair, and bone contains perhaps the largest store of TGF-␤ in the body (reviewed in Ref. 3). Bone cells exhibit conventional type II and type III TGF-␤ receptors (TRII and TRIII) that influence TGF-␤ binding to type I receptor (TRI) or its activation, both essential for TGF-␤-dependent events (4 -6). There are few systems where regulation of TRI expression has been examined in detail and where functional changes correlate with these variations. We found TRI levels specifically maintained on differentiated bone cells in vitro, despite decreases in TRII and TRIII in response to bone morphogenetic protein 2 (5). In contrast, high levels of glucocorticoid rapidly reduce the proportion of TGF-␤ binding to TRI on bone cells and correspondingly decrease TGF-␤ activity (6).To understand these events further, we cloned the rat TRI promoter and observed higher promoter activity in osteoblastlike cells compared with undifferentiated bone cells or dermal fibroblasts (7). The TRI promoter includes a CpG island, several transcription factor Sp1 binding sites consistent with constitutive expression by many cells, and six cis-acting elements for transcription factors, termed CBFa (7-8).2 Whereas CBFa2 and CBFa3 are important gene regulators in lymphoid cells (9), CBFa1 expression increases in parallel with osteoblast differentiation in vitro (10).2 Moreover, targeted disruption of the CBFa1 gene eliminates osteogenesis in mice, and insertion, deletion, or missense mutations in CBFa1 occur in humans with the skeletal disorder cleidocranial dysplasia (11). Genes directly affected by CBFa1, especially those important for skeletal developme...

Transcription factor CCAAT/enhancer-binding protein ␦ (C/EBP␦) is normally associated with acute-phase gene expression. However, it is expressed constitutively in primary osteoblast cultures where it increases insulin-like growth factor I synthesis in a cAMP-dependent way. Here we show that the 3 proximal region of the C/EBP␦ gene promoter contains a binding sequence for Runt domain factor Runx2, which is essential for osteogenesis. This region of the C/EBP␦ promoter directed high reporter gene expression in osteoblasts, and specifically bound Runx2 in osteoblast-derived nuclear extract. C/EBP␦ gene promoter activity was reduced by mutating the Runx binding sequence or by co-transfecting with Runx2 antisense expression plasmid, and was enhanced by overexpression of Runx-2. Exposure to prostaglandin E 2 increased Runx-dependent gene transactivation independently of Runx2 binding to DNA. Runx2 bound directly to the carboxyl-terminal region of C/EBP␦ itself, and its ability to drive C/EBP␦ expression was suppressed when C/EBP␦ or its carboxyl-terminal fragment was increased by overexpression. Consistent effects also occurred on C/EBP␦-dependent increases in gene expression driven by synthetic or insulin-like growth factor I gene promoter fragments. These interactions between Runx2 and C/EBP␦, and their activation by prostaglandin E 2 , provide new evidence for their importance during skeletal remodeling, inflammatory bone disease, or fracture repair.

Extracellular glutathione peroxidase (EGPx) is a glycosylated selenoprotein capable of reducing hydrogen peroxide, organic hydroperoxides, free fatty acid hydroperoxides, and phosphatidylcholine hydroperoxides. We found that human large intestinal explant cultures synthesize EGPx and cellular glutathione peroxidase (CGPx) and secrete EGPx. The level of EGPx mRNA expression relative to α-tubulin was similar throughout the mouse gastrointestinal tract. EGPx mRNA transcripts have been localized to mature absorptive epithelial cells in human and mouse large intestine. Western blot analysis of mouse intestinal protein has demonstrated the presence of EGPx protein in the small intestine, cecum, and large intestine, with the highest protein levels found in the cecum. Immunohistochemistry studies of human large intestine and mouse small and large intestine sections demonstrated the presence of EGPx protein within mature absorptive epithelial cells. In human large intestine and mouse small intestine, EGPx protein is also present in the extracellular milieu. These results suggest a role for EGPx in protection of the intestinal tract from peroxidative damage and/or in intercellular metabolism of peroxides.

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Anterior table frontal sinus fractures can be endoscopically repaired with either a standard 0.85 mm sheet or a prefabricated implant. Clinical application of this technique would be expected to reduce operating time, surgical morbidity, and cost.

Background:To avoid a static double-eyelid fold characterized by nonmobile overdepression of the fold, we propose a new surgical approach of using septoaponeurosis junctional thickening (SAJT) to create a dynamic fold.Methods:Six hundred eighty patients underwent double-eyelid surgery using the SAJT fixation technique. The orbital septum was exposed and transversely opened superior to the incision margin. The lower septal stump was trimmed to expose the SAJT. The dermis and orbicularis oculi muscle of the lower flap of the upper eyelid were attached to the SAJT. Patients were followed for 2–8 years (mean, 3.6 y). Anatomic study with 28 upper eyelids from 28 Korean adult cadavers was performed to confirm the histological structure of the SAJT.Results:This technique created a dynamic fold. When the eyes were open, the fold depth was moderate. When the eyes were closed, the fold site was smooth and not depressed. The surgery had a 95% patient satisfaction rate (365 responded as satisfied and 236 responded as very satisfied). Postoperative complications included partial or complete loss of the double-eyelid line in 14 and 4 cases, respectively, hypertrophic scar formation in 7 cases, and asymmetric fold in 8 cases.Conclusions:The authors introduce a double-eyelid surgery technique using the SAJT. This SAJT fixation technique creates a dynamic double-eyelid fold. Our study showed a high patient satisfaction rate and that the resulting fold mimics the movement of the congenital supratarsal fold in Asians.

Acute alkalosis-induced pulmonary vasodilation and acidosis-induced pulmonary vasoconstriction have been well described, but responses were generally measured within 5-30 min of changing pH. In contrast, several in vitro studies have found that relatively brief periods of sustained alkalosis can enhance, and sustained acidosis can decrease, vascular reactivity. In this study of intact newborn piglets, effects of acute (20 min) and sustained (60-80 min) alkalosis or acidosis on baseline (35% O2) and hypoxic (12% O2) pulmonary vascular resistance (PVR) were compared with control piglets exposed only to eucapnia. Acute alkalosis decreased hypoxic PVR, but sustained alkalosis failed to attenuate either baseline PVR or the subsequent hypoxic response. Acute acidosis did not significantly increase hypoxic PVR, but sustained acidosis markedly increased both baseline PVR and the subsequent hypoxic response. Baseline PVR was similar in all piglets after resumption of eucapnic ventilation, but the final hypoxic response was greater in piglets previously exposed to alkalosis than in controls. Thus, hypoxic pulmonary vasoconstriction was not attenuated during sustained alkalosis, but was accentuated during sustained acidosis and after the resumption of eucapnia in alkalosis-treated piglets. Although extrapolation of data from normal piglets to infants and children with pulmonary hypertension must be done with caution, this study suggests that sustained alkalosis may be of limited efficacy in treating acute hypoxia-induced pulmonary hypertension and the risks of pulmonary hypertension must be considered when using ventilator strategies resulting in permissive hypercapnic acidosis.