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Humans living at high-altitude (HA) have adapted to this environment by increasing pulmonary vascular and alveolar growth. RNA sequencing data from a novel murine model that mimics this phenotypical response to HA suggested estrogen signaling via estrogen receptor alpha (ERα) may be involved in this adaptation. We hypothesized ERα was a key mediator in the cardiopulmonary adaptation to chronic hypoxia and sought to delineate the mechanistic role ERα contributes to this process by exposing novel loss-of-function ERα mutant (ERαMut) rats to simulated HA. ERα mutant or wild-type (wt) rats were exposed to normoxia or hypoxia starting at conception and continued postnatally until 6 wk of age. Both wt and ERαMut animals born and raised in hypoxia exhibited lower body mass and higher hematocrits, total alveolar volumes (V a ), diffusion capacities of carbon monoxide (DLCO), pulmonary arteriole (PA) wall thickness, and Fulton indices than normoxia animals. Right ventricle adaptation was maintained in the setting of hypoxia. Although no major physiologic differences were seen between wt and ERαMut animals at either exposure, ERαMut animals exhibited smaller mean linear intercepts (MLI) and increased PA total and lumen areas. Hypoxia exposure or ERα loss-of-function did not affect lung mRNA abundance of vascular endothelial growth factor, angiopoietin 2, or apelin. Sexual dimorphisms were noted in PA wall thickness and PA lumen area in ERαMut rats. In summary, in room air-exposed rats and rats with peri- and postnatal hypoxia exposure, ERα loss-of-function was associated with decreased alveolar size (primarily driven by hypoxic animals) and increased PA remodeling. NEW & NOTEWORTHY By exposing novel loss-of-function estrogen receptor alpha (Erα) mutant rats to a novel model of human high-altitude exposure, we demonstrate that ERα has subtle but inconsistent effects on endpoints relevant to cardiopulmonary adaptation to chronic hypoxia. Given that we observed some histologic, sex, and genotype differences, further research into cell-specific effects of ERα during hypoxia-induced cardiopulmonary adaptation is warranted.

We have shown that cigarette smoke (CS)-induced pulmonary emphysema-like manifestations are preceded by marked suppression of the number and function of bone marrow hematopoietic progenitor cells (HPCs). To investigate whether a limited availability of HPCs may contribute to CS-induced lung injury, we used a Food and Drug Administration-approved antagonist of the interactions of stromal cell-derived factor 1 (SDF-1) with its chemokine receptor CXCR4 to promote intermittent HPC mobilization and tested its ability to limit emphysema-like injury following chronic CS. We administered AMD3100 (5mg/kg) to mice during a chronic CS exposure protocol of up to 24 wk. AMD3100 treatment did not affect either lung SDF-1 levels, which were reduced by CS, or lung inflammatory cell counts. However, AMD3100 markedly improved CS-induced bone marrow HPC suppression and significantly ameliorated emphysema-like end points, such as alveolar airspace size, lung volumes, and lung static compliance. These results suggest that antagonism of SDF-1 binding to CXCR4 is associated with protection of both bone marrow and lungs during chronic CS exposure, thus encouraging future studies of potential therapeutic benefit of AMD3100 in emphysema.

17β-estradiol (E2) exerts complex and context-dependent effects in pulmonary hypertension. In hypoxia-induced pulmonary hypertension (HPH), E2 attenuates lung vascular remodeling through estrogen receptor (ER)-dependent effects; however, ER target genes in the hypoxic lung remain unknown. In order to identify the genome regulated by the E2-ER axis in the hypoxic lung, we performed a microarray analysis in lungs from HPH rats treated with E2 (75 mcg/kg/day) ± ER-antagonist ICI182,780 (3 mg/kg/day). Untreated HPH rats and normoxic rats served as controls. Using a false discovery rate of 10%, we identified a significantly differentially regulated genome in E2-treated versus untreated hypoxia rats. Genes most upregulated by E2 encoded matrix metalloproteinase 8, S100 calcium binding protein A8, and IgA Fc receptor; genes most downregulated by E2 encoded olfactory receptor 63, secreted frizzled-related protein 2, and thrombospondin 2. Several genes affected by E2 changed in the opposite direction after ICI182,780 co-treatment, indicating an ER-regulated genome in HPH lungs. The bone morphogenetic protein antagonist Grem1 (gremlin 1) was upregulated by hypoxia, but found to be among the most downregulated genes after E2 treatment. Gremlin 1 protein was reduced in E2-treated versus untreated hypoxic animals, and ER-blockade abolished the inhibitory effect of E2 on Grem1 mRNA and protein. In conclusion, E2 ER-dependently regulates several genes involved in proliferative and inflammatory processes during hypoxia. Gremlin 1 is a novel target of the E2-ER axis in HPH. Understanding the mechanisms of E2 gene regulation in HPH may allow for selectively harnessing beneficial transcriptional activities of E2 for therapeutic purposes.

17β-Estradiol (E2) exerts protective effects on right ventricular (RV) function in pulmonary arterial hypertension (PAH). Since acute exercise-induced increases in afterload may lead to RV dysfunction in PAH, we sought to determine whether E2 allows for superior RV adaptation after an acute exercise challenge. We studied echocardiographic, hemodynamic, structural, and biochemical markers of RV function in male and female rats with sugen/hypoxia (SuHx)-induced pulmonary hypertension, as well as in ovariectomized (OVX) SuHx females, with or without concomitant E2 repletion (75 μg·kg(-1)·day(-1)) immediately after 45 min of treadmill running at 75% of individually determined maximal aerobic capacity (75% aerobic capacity reserve). Compared with males, intact female rats exhibited higher stroke volume and cardiac indexes, a strong trend for better RV compliance, and less pronounced increases in indexed total pulmonary resistance. OVX abrogated favorable RV adaptations, whereas E2 repletion after OVX markedly improved RV function. E2's effects on pulmonary vascular remodeling were complex and less robust than its RV effects. Postexercise hemodynamics in females with endogenous or exogenous E2 were similar to hemodynamics in nonexercised controls, whereas OVX rats exhibited more severely altered postexercise hemodynamics. E2 mediated inhibitory effects on RV fibrosis and attenuated increases in RV collagen I/III ratio. Proapoptotic signaling, endothelial nitric oxide synthase phosphorylation, and autophagic flux markers were affected by E2 depletion and/or repletion. Markers of impaired autophagic flux correlated with endpoints of RV structure and function. Endogenous and exogenous E2 exerts protective effects on RV function measured immediately after an acute exercise challenge. Harnessing E2's mechanisms may lead to novel RV-directed therapies.

Background: Abdominal catastrophe in the severely burned patient without abdominal injury has been described. We perceived an alarming recent incidence of this complication in our burn center, both during acute resuscitation and later in the hospital course. We sought to define incidence, outcomes, and associated factors, such as excessive resuscitation volume and treatment issues., Study Design: We examined all severely burned military and civilian patients with abdominal pathology between March 2003 and February 2008. Data included age, gender, total body surface area burn, inhalation injury, Injury Severity Score, disposition, resuscitation volume, time from injury to diagnosis, use of recombinant factor VIIa, vasopressors, and early tube feedings. We assembled a Delphi panel of surgeons experienced in abdominal catastrophes to review these data., Results: Among 1,825 patients admitted to the US Army Institute of Surgical Research Burn Center, 120 (6.6%) were diagnosed with abdominal pathology (burn size 48% +/- 19%), of which 51 (2.8%) had abdominal catastrophe. The majority of these occurred in the first days after injury with associated abdominal compartment syndrome (32 of 51) and increased linearly to burn size. We noted another group of patients who presented primarily with ischemic bowel later in the course, with the same clinical presentation. Resuscitation volume was 6.02 mL/kg/percent total body surface area burned. Vasopressors were used in 71% of patients and tube feedings in 57% before diagnosis., Conclusions: Abdominal catastrophe without abdominal trauma occurs in 2.8% of our population. Associated mortality was 78% without obvious cause. Delphi panel experts recommended more aggressive monitoring of abdominal compartment pressures and earlier operative management to improve outcomes.

Objective: To determine if intraarticular (IA) injection of hyaluronan (HA) into the canine knee after anterior cruciate ligament transection (ACLT) alters the progression of osteoarthritis (OA) and the perception of pain in this model., Methods: OA was induced in 30 adult dogs of mixed breed by ACLT. The dogs were divided into 3 groups and given 5 weekly IA injections into the unstable knee during Weeks 1-5 and 13-17. The prophylactic treatment group received HA in the first series and saline during the second series. The therapeutic group received saline in the first series and HA in the second series. The control group received saline during both injection series. The progression of joint damage of OA was evaluated by arthroscopy 12 weeks after ACLT and by gross examination 32 weeks after ACLT. Histologic and biochemical changes of OA were evaluated. Loading of the unstable limb during gait was determined by force-plate analysis before surgery, after each series of injections, and the week before euthanasia., Results: Arthroscopic examination 12 weeks after ACLT revealed OA changes in the cruciate-deficient knees. Chondropathy scores ranged from 0 to 8 (possible range 0-65). The mean chondropathy score was 2.5 +/- 1.3 (mean +/- SD) for the controls, 2.5 +/- 2.5 for the therapeutic group, and 2.1 +/- 1.3 for the prophylactic group. At the termination of the experiment 32 weeks after ACLT, the gross chondropathy scores were 14.0 +/- 5.2 for controls, 17.6 +/- 6.8 for the therapeutic group, and 13.3 +/- 5.0 for the prophylactic group. There were no significant differences among the means of the gross scores, the histologic scores, or biochemical composition of articular cartilage. The peak vertical ground reaction force (VGRF) generated by the unstable limb was reduced by ~60% after ACLT, and slowly increased to ~75% of the baseline value over the 32 weeks after ACLT. HA injection had no effect on the VGRF or on the pathologic changes of OA., Conclusion: Intraarticular HA injection did not alter the progression of OA in the cruciate-deficient canine knee or alter the loading of the unstable limb.

Objective: To examine the relationship between the severity of cartilage damage and the severity of meniscus damage after transection of the anterior cruciate ligament (ACLT) in adult dogs., Design: Data were obtained from 40 dogs which underwent ACLT and from three additional sham-operated dogs that were subjected to arthrotomy but not ligament transection. Joint pathology was analysed 12, 24 or 32 weeks after surgery. The severity of damage to the articular cartilage on the femoral condyle and tibial plateau was graded with a scoring system based on that of the Sociètè Française d'Arthroscopie and meniscus damage was graded on a 0-4 scale., Results: No damage to the meniscus or articular cartilage was observed 12 weeks after surgery in the dogs subjected only to arthrotomy. In contrast, tears of the medial meniscus were observed in two of 10 (20%) dogs examined 12 weeks after ACLT. The incidence of severe tears increased to 86% and 84% after 24 weeks and 32 weeks, respectively. Damage to the lateral meniscus was mild, with only 7.5% of all dogs with a cruciate-deficient knee having a bucket handle or complete tear. Most of the unstable knees exhibited ulceration of the articular cartilage of the femoral condyles and tibial plateaus 12 weeks (mean chondropathy score+/-standard deviation 11.9+/-8.5, N=10), 24 weeks (7.9+/-5.0, N=7), and 32 weeks (7.1+/-5.5, N=23) after ACLT. The mean chondropathy scores for the tibial plateaus were similar to those for the femoral condyles. No correlation was apparent between the severity of cartilage damage and of meniscus damage for either joint surface., Conclusion: 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., (Copyright 2002 OsteoArthritis Research Society International.)

Objective: Considerable interest exists today in biochemical or immunochemical tests for monitoring the progression of osteoarthritis (OA). It has been suggested that measurements made on synovial fluid (SF) will more accurately reflect the magnitude of cartilage destruction in an index joint than those performed on serum. However, we have shown that the synovitis that occurs in OA affects the rate of protein clearance from the joint. We tested the hypothesis that if adjusted for clearance rate, the SF concentration of cartilage proteoglycans (PG) estimates severity of chondropathy and predicts progression of cartilage damage more accurately than if clearance is not taken into account., Methods: Clearance of radioiodinated serum albumin (RISA), a surrogate for the clearance of PG, was measured in 19 adult dogs at baseline and again 16 weeks and 32 weeks after anterior cruciate ligament transection (ACLT). Severity of chondropathy was determined arthroscopically after 16 weeks of instability and at postmortem 32 weeks after ACLT., Results: Adjustment for the RISA clearance rate showed that the SF PG concentration markedly underestimated the quantity of PG released from the OA cartilage. Regardless of whether the concentration was adjusted for clearance, no correlation existed between the SF PG level and the severity of chondropathy. Further, the SF concentration of PG 16 weeks after ACLT failed to predict severity of cartilage damage at postmortem., Conclusion: SF concentration of a cartilage derived molecule is unlikely to predict the course of cartilage damage in an OA joint over time or in response to treatment with a potential disease modifying OA drug.

Objective: To determine if diacerhein protects against the early stages of joint damage in a canine model of osteoarthritis (OA)., Methods: OA was induced in 20 adult mongrel dogs by transection of the anterior cruciate ligament of the left knee. Beginning the day after surgery, dogs in the active treatment group were dosed twice a day with capsules of diacerhein, providing a total daily dose of 40 mg/kg, for 32 weeks. Dogs in the control group received placebo capsules on the same schedule. Pathology in the unstable knee was assessed arthroscopically 16 weeks after surgery and by direct observation when the dogs were killed 32 weeks after surgery. The severity of gross joint pathology was recorded, and samples of the medial femoral condyle cartilage and the synovial tissue adjacent to the central portion of the medial meniscus were collected for histologic evaluation. Water content and uronic acid concentration of the articular cartilage from the femoral condyle were determined, and collagenolytic activity in extracts of cartilage pooled from the medial and lateral tibial plateaus was assayed against 14C-labeled collagen fibers., Results: Diacerhein treatment slowed the progression of OA, as measured by grading of gross changes in the unstable knee at arthroscopy 16 weeks after cruciate ligament transection (P = 0.04) and at the time the animals were killed, 32 weeks after surgery (P = 0.05). However, 32 weeks after ACL transection, the mean proteoglycan concentration and water content of the OA cartilage and the level of collagenolytic activity in extracts of the cartilage were not significantly different in the diacerhein treatment group than in the placebo treatment group., Conclusion: Diacerhein treatment significantly reduced the severity of morphologic changes of OA compared with placebo. These findings support the view that diacerhein may be a disease-modifying drug for OA.

Objective: Osteoarthritis (OA) is characterized by progressive loss of articular cartilage in the involved joint. Accurate, reproducible measurement of the thickness of the cartilage in vivo, however, is difficult. Because development of an ultrasonic imaging device for intraarticular use is feasible and would permit acquisition of information that could complement the assessment of articular cartilage made at arthroscopy, we evaluated the efficacy of high frequency ultrasound in assessing the thickness and subsurface characteristics of normal and OA cartilage., Methods: Blocks of human femoral cartilage and subchondral bone and chips of cartilage alone were examined in vitro with an experimental 25 MHz pulse-echo ultrasound scanner that portrayed cross sections of the cartilage as B-mode images. The gross and histologic appearance of the articular surface was used to identify specimens of unblemished, normal cartilage and OA cartilage. The speed of sound in cartilage, determined from measurements of cartilage thickness and sound transmission, was related to its biochemical composition., Results: The speed of sound in normal cartilage (1658 +/- 185 m/s, n = 27) was greater than that in OA cartilage (1581 +/- 148 m/s, n = 40, p = 0.06), but was not related to the cartilage water content or the concentration of uronic acid or hydroxyproline. Images of normal cartilage showed a smooth echo band at the tissue surface with a hypoechoic matrix; in scans of fibrillated cartilage the width of this band was proportional to the depth of fibrillation (r = 0.78). Ultrasonic and histologic measurements of OA cartilage thickness were closely correlated (r = 0.87) and the mean coefficient of variation for repeated measurements was 2%., Conclusion: High frequency ultrasonic images obtained in vitro provide highly accurate and reproducible measurements of the thickness and subsurface characteristics of normal and OA articular cartilage.

The effects of tiaprofenic acid (TPA), a nonsteroidal antiinflammatory drug with high potency as a cyclooxygenase inhibitor, on the metabolism of normal and degenerating articular cartilage were examined. When present in the culture medium in clinically relevant concentrations encompassing those achieved in synovial fluid of patients treated with the drug, TPA had no significant effects on net proteoglycan synthesis in organ cultures of normal, osteoarthritic or atrophic canine articular cartilage. When fed to dogs for 8 weeks in a daily dose of 100 mg, TPA had no apparent effect on cartilage water content or uronic acid concentration. The suppression of net cartilage proteoglycan synthesis caused by immobilization was not affected by administration of TPA nor did the drug affect the proportion of newly synthesized glycosaminoglycans recovered from the spent culture medium, suggesting that it did not increase proteoglycan catabolism or affect the integrity of the cartilage matrix.

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 less than 0.01). Iron deposits were present in 75% of synovial samples obtained after routine ACLT, but in only 6% (P less than 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.

Roxarsone (4-hydroxy-3-nitrobenzenearsonic acid) is extracted from the premix with aqueous 1% ammonium carbonate. The extract is filtered, diluted, and analyzed by atomic absorption spectrophotometry, using an air-acetylene flame and an arsenic electrodeless discharge lamp. The instrument response of the sample is compared to that of a standard solution of arsenic trioxide. Recoveries range from 99.7. to 100.4% and coefficients of variation range from 0.35 to 0.63%.

Salicylates suppress net glycosaminoglycan synthesis in articular cartilage. The inhibitory effect is greater in osteoarthritic (OA) cartilage than in normal cartilage. Whether the isolated OA chondrocyte is inherently more susceptible to the effects of salicylate on glycosaminoglycan metabolism has not been determined. The results of this study show that, after isolation from the extracellular matrix, normal and OA chondrocytes in suspension culture are similarly susceptible to the metabolic effects of salicylate. However, chondrocytes from the contralateral knees of dogs with unilateral OA were notably resistant to the effects of salicylate.