E2 attenuates hemodynamic and remodeling parameters in HPH in an ER-dependent manner, through direct antiproliferative mechanisms on vascular cells, which may provide novel nonhormonal therapeutic targets for HPH.

Estrogens are disease modifiers in PAH. Even though female patients exhibit better right ventricular (RV) function than men, estrogen effects on RV function (a major determinant of survival in PAH) are incompletely characterized. We sought to determine whether sex differences exist in RV function in the SuHx model of PAH, whether hormone depletion in females worsens RV function, and whether E2 repletion improves RV adaptation. Furthermore, we studied the contribution of ERs in mediating E2's RV effects. SuHx-induced pulmonary hypertension (SuHx-PH) was induced in male and female Sprague-Dawley rats as well as OVX females with or without concomitant E2 repletion (75 μg·kg(-1)·day(-1)). Female SuHx rats exhibited superior CI than SuHx males. OVX worsened SuHx-induced decreases in CI and SuHx-induced increases in RVH and inflammation (MCP-1 and IL-6). E2 repletion in OVX rats attenuated SuHx-induced increases in RV systolic pressure (RVSP), RVH, and pulmonary artery remodeling and improved CI and exercise capacity (V̇o2max). Furthermore, E2 repletion ameliorated SuHx-induced alterations in RV glutathione activation, proapoptotic signaling, cytoplasmic glycolysis, and proinflammatory cytokine expression. Expression of ERα in RV was decreased in SuHx-OVX but was restored upon E2 repletion. RV ERα expression was inversely correlated with RVSP and RVH and positively correlated with CO and apelin RNA levels. RV-protective E2 effects observed in females were recapitulated in male SuHx rats treated with E2 or with pharmacological ERα or ERβ agonists. Our data suggest significant RV-protective ER-mediated effects of E2 in a model of severe PH.

Objective. To evaluate the sequence of changes in articular cartilage, trabecular bone, and subchondral plate in dogs with osteoarthritis (OA), 3 months, 18 months, and 54 months after anterior cruciate ligament transection (ACLT).Methods. Specimens of the medial tibial plateau Submitted for publication May 5 , 1992; accepted in revised form February 9, 1993. were analyzed with microscopic computed tomography (micro-CT) at a resolution of 60 pm, and biochemical and morphologic changes in the femoral articular cartilage were assessed.Results. At 3 months and 18 months after ACLT, the articular cartilage in the unstable knee showed histologic changes typical of early OA and increased water content and uronic acid concentration; by 54 months, full-thickness ulceration had developed. Micro-CT analysis showed a loss of trabecular bone in the unstable knee, compared with the contralateral knee, at all time points. Al. both 18 and 54 months, the differences in trabecular thickness and surface-tovolume ratio were greater than at 3 months. Although the mean subchondral plale thickness, especially in the medial aspect of the medial tibial plateau, was greater in the OA knee than in the contralateral knee 18 months and 54 months after ACLI', these differences were not statistically significant; however, the difference was significantly greater at 54 months than at 3 months.Conclusion. Thickening of the subchondral bone is not required for the development of cartilage changes of OA in this model. The bony changes that develop after ACLT, however, could result in abnormal transmission of stress to the overlying cartilage and thereby contribute to the progression of cartilage degeneration.In the pathogenesis of osteoarthritis (OA), interactions among all the major joint tissues, including the articular cartilage, synovium, and subchondral bone, have been implicated (1). While a large body of work has focused on the alterations in the articular cartilage in OA in humans and experimental animal

Fibroblast growth factor 23 (FGF23) gain of function mutations can lead to autosomal dominant hypophosphatemic rickets (ADHR) disease onset at birth, or delayed onset following puberty or pregnancy. We previously demonstrated that the combination of iron deficiency and a knock-in R176Q FGF23 mutation in mature mice induced FGF23 expression and hypophosphatemia that paralleled the late-onset ADHR phenotype. Because anemia in pregnancy and in premature infants is common, the goal of this study was to test whether iron deficiency alters phosphate handling in neonatal life. Wild-type (WT) and ADHR female breeder mice were provided control or iron-deficient diets during pregnancy and nursing. Iron-deficient breeders were also made iron replete. Iron-deficient WT and ADHR pups were hypophosphatemic, with ADHR pups having significantly lower serum phosphate (p < 0.01) and widened growth plates. Both genotypes increased bone FGF23 mRNA (>50 fold; p < 0.01). WT and ADHR pups receiving low iron had elevated intact serum FGF23; ADHR mice were affected to a greater degree (p < 0.01). Iron-deficient mice also showed increased Cyp24a1 and reduced Cyp27b1, and low serum 1,25-dihydroxyvitamin D (1,25D). Iron repletion normalized most abnormalities. Because iron deficiency can induce tissue hypoxia, oxygen deprivation was tested as a regulator of FGF23, and was shown to stimulate FGF23 mRNA in vitro and serum C-terminal FGF23 in normal rats in vivo. These studies demonstrate that FGF23 is modulated by iron status in young WT and ADHR mice and that hypoxia independently controls FGF23 expression in situations of normal iron. Therefore, disturbed iron and oxygen metabolism in neonatal life may have important effects on skeletal function and structure through FGF23 activity on phosphate regulation.

Anterior cruciate ligament transection (ACLT) in the dog results in osteophyte formation and in morphologic, metabolic, biochemical, and biomechanical changes in the articular cartilage of the unstabIe knee that mimic those of human osteoarthritis (OA). However, in dogs studied up to 2 years after ACLT, the changes have appeared to be self-limiting, which has led to the suggestion that this is a model of cartilage damage and repair, rather than of OA. To ascertain whether changes in articular cartilage and subchondral bone of dogs subjected to ACLT lead to progressive changes of OA, we studied 3 dogs for 54 months after ACLT. Arthrotomy was performed in the dogs to visualize and then transect the anterior cruciate ligament. When the dogs were killed, full-thickness ulceration of the articular cartilage was seen on the medial femoral condyle and tibia1 plateau of the unstable knee, while cartilage in other regions was thicker than that of the contralateral knee, consistent with hypertrophic cartilage repair. Synovial infiltration by mononuclear cells was not more severe than that seen in dogs killed at earlier intervals after ACLT, although gross fibrotic thickening of the capsule was apparent in each dog. Histomorphometric studies revealed a marked increase in subchondral bone volume and active bone formation. These findings show that the changes that develop in the canine knee joint after ACLT are progressive and are unambiguously those of OA. Anterior cruciate ligament transection (ACLT)in the dog results in the formation of osteophytes and in morphologic, metabolic, biochemical, and biomechanical changes in the articular cartilage of the unstable knee that mimic those in the early stages of human osteoarthritis (OA) (1-3). However, in the canine model, full-thickness loss of cartilage has rarely been observed; the cartilage lesions have appeared to be essentially self-limiting. Marshall and Olsson attributed this lack of progression to buttressing of the unstable joint by large osteophytes and capsular fibrosis (4). In dogs studied up to 64 weeks after anterior cruciate ligament transection, we have found that the total amount of proteoglycans (PG), the PG concentration, and the rate of net PG synthesis in articular cartilage from the unstable knee are often elevated, and that these changes are associated with a striking increase in bulk of the articular cartilage in the unstable knees (5). We suggested that this represents a hypertrophic repair phase of OA. Taking into account also the findings that gait analyses showed no progresRheumatology Division, Indiana University School of Medicine, 541 Clinical Drive, Room 492, Indianapolis, IN 46202.Submitted for publication March 13, 1991; accepted in revised form July 7, 1991.sive diminution in ground reaction forces (6), -that radiographs obtained under anesthesia showed no decrease in range of motion of the unstable knee, and

Smoking causes lung cancer and chronic obstructive pulmonary disease (COPD) that impose severe health problem to humans. Both diseases are related to each other and can be induced by chronic inflammation in the lung. To identify the molecular mechanism for lung cancer formation, a CCSP-rtTA/(Teto)7Stat3C bitransgenic model was generated recently. In this model, persistent activation of the Stat3 signaling pathway induced pulmonary inflammation and adenocarcinoma formation in the lung. A group of Stat3 downstream genes were identified by Affymetrix GeneChip microarray analysis that can be used as biomarkers for lung cancer diagnosis and prognosis. To determine which human lung cancers are related to the Stat3 pathway, multiple Stat3 downstream genes were screened in human lung cancers (adenocarcinomas and squamous cell carcinomas) and lung tissue with COPD. In both cancer and COPD, the Stat3 gene was up-regulated. A panel of Stat3-up-regulated downstream genes in mice was up-regulated in human adenocarcinomas, but not in human squamous cell carcinomas. This panel of genes was also modestly up-regulated in lung tissue with COPD from patients with a history of smoking and not up-regulated in those without histories of smoking. Several Stat3-down-regulated downstream genes also showed differential expression patterns in carcinoma and COPD. These studies support a concept that Stat3 is a potent oncogenic molecule that plays a role in formation of lung adenocarcinomas in both mice and humans. The carcinogenesis of adenocarcinoma and squamous cell carcinoma is mediated by different molecular mechanisms and pathways in vivo. Stat3 and its downstream genes can serve as biomarkers for lung adenocarcinoma and COPD diagnosis and prognosis in mice and humans.

Damage to the medial meniscus is a consistent feature of the pathology which develops in the canine knee after ACLT, but the severity of cartilage damage is not correlated with the severity of meniscal damage.

Anterior cruciate ligament transection (ACLT) in the dog produces changes in the articular cartilage of the unstable knee that are consistent with those of osteoarthritis (OA). To determine whether the degrees of severity of OA cartilage changes, of synovitis, and of synovial iron deposition were related to adequacy of hemostasis at the time of ACLT, a modified surgical technique was devised, whereby electrocautery was used to obtain meticulous control of bleeding when the ligament was severed and irrigation was used to remove intraarticular blood before closure of the joint. When no particular attention was given to hemostasis, 69% of the dogs showed synovitis in the OA knee 10 weeks after ACLT; when electrocautery and irrigation were used to maintain hemostasis, synovitis was present in only 24% of the OA knees 10 weeks after ACLT (P < 0.01). Ironl deposits were present in 75% of synovial samples obtained after routine ACLT, but in only 6% (P < 0.001) when attention was given to hemostasis. Hypertrophy of articular cartilage, chondrocyte cloning, fibrillation, and changes in tangential zone chondrocytes were less prominent in the OA knee when electrocautery and irrigation were used. However, the water content, uronic acid concentration, and rate of net 35S-labeled glycosaminoglycan synthesis were similarly increased regardless of the surgical technique used, and presumably, these changes reflect the reaction of joint cartilage to mechanical instability in this model of OA.Anterior cruciate ligament transection (ACLT) in the dog produces a mechanically unstable stifle joint whose articular cartilage develops biochemical, metabolic, and histologic changes that mimic those of osteoarthritis (OA) in humans (1-3). The synovium from the OA joint shows a variable amount of inflammation, with mononuclear cell infiltration, lining cell hyperplasia, and fibrosis (4-7). In contrast, no cartilage abnormalities and only transient synovitis are seen in "sham operated" joints, in which the cruciate ligament is visualized but not cut (43).Although this experimental model of OA has been used in many laboratories, the severity of the pathologic changes has varied (3,8). The basis for such variability is unclear, but could be related to such factors as the animal's age, weight, or breed, the postoperative exercise regimen, or the length of time from surgery to death of the animal (8).One additional variable is the surgical procedure itself. In some cases, the anterior cruciate ligament is transected by a blind stab incision with a