Haem is associated with thrombosis in neonates and infants undergoing cardiac surgery for congenital heart disease.

BACKGROUND: Haem levels are associated with thrombosis in a variety of diseases, as well as being a contributing cause of thrombotic events in animal models. MATERIALS AND METHODS: We retrospectively analyzed samples from 39 children who underwent cardiac surgery with cardiopulmonary bypass, including 15 children who developed a postoperative thrombosis and 24 controls. RESULTS: Patients who developed thrombosis postoperatively had statistically significant higher average haem levels over time (presurgery to 12 h postsurgery) compared to patients who did not develop thrombosis. CONCLUSION: Higher cell-free total haem levels are associated with a higher risk of thrombosis in a paediatric cardiac surgical cohort.

Baseline mineralizing surface determines the magnitude of the bisphosphonate effect on cortical bone mineralization in postmenopausal osteoporotic patients.

PURPOSE: To determine the effect of short- or long-term bisphosphonate treatment on cortical bone mineralization density distribution (BMDD). METHODS: BMDD was assessed by quantitative backscatter electron imaging in postmenopausal osteoporosis: in paired transiliac biopsy samples (n=36) at baseline and after 3 years risedronate treatment from a clinical study, in transiliac biopsy samples from patients who were treated with either risedronate (n=31) or alendronate (n=68) for 3 to 7 years from an observational study. Outcomes were related to premenopausal reference data (n=73) and to histomorphometric mineralizing surface per bone surface (MS/BS). RESULTS: In the clinical study, patients with lower (below cohort median) MS/BS had normal cortical CaMean at baseline. After 3 years risedronate, their CaMean was not different versus baseline but increased versus reference (+2.9%, p=0.003). Among the groups of the observational study, CaMean did not exceed reference level, was similar for alendronate versus risedronate and similar between 3 to 5 years versus longer than 5 years treatment duration. CONCLUSION: Baseline bone mineralizing surface appears to be important for the effect of bisphosphonate on cortical bone mineralization. In patients with lower baseline MS/BS, level of mineralization after treatment can exceed reference level. Whether this is beneficial in the long-term is unknown.

Maresin 1 induces a novel pro-resolving phenotype in human platelets.

Essentials Specialized proresolving mediators (SPMs) promote the resolution of inflammation. This study sought to investigate the effects of SPMs on human platelet function. The SPM, Maresin 1, enhanced hemostatic, but suppressed inflammatory functions of platelets. SPMs uniquely regulate platelet function and may represent a new class of antiplatelet agents. SUMMARY: Background Antiplatelet therapy is a cornerstone of modern medical practice and is routinely employed to reduce the likelihood of myocardial infarction, thrombosis and stroke. However, current antiplatelet therapies, such as aspirin, often have adverse side-effects, including increased risk of bleeding, and some patients are relatively 'aspirin-resistant'. Platelets are intimately involved in hemostasis and inflammation, and clinical consequences are associated with excessive or insufficient platelet activation. Objectives A major unmet need in the field of hematology is the development of new agents that safely prevent unwanted platelet activation in patients with underlying cardiovascular disease, while minimizing the risk of bleeding. Here, we investigate the potential of endogenously produced, specialized pro-resolving mediators (SPMs) as novel antiplatelet agents. SPMs are a recently discovered class of lipid-derived molecules that drive the resolution of inflammation without being overtly immunosuppressive. Methods Human platelets were treated with lipoxin A4, resolvin D1, resolvin D2, 17-HDHA or maresin 1 for 15 min, then were subjected to platelet function tests, including spreading, aggregation and inflammatory mediator release. Results We show for the first time that human platelets express the SPM receptors, GPR32 and ALX. Furthermore, our data demonstrate that maresin 1 differentially regulates platelet hemostatic function by enhancing platelet aggregation and spreading, while suppressing release of proinflammatory and prothrombotic mediators. Conclusions These data support the concept that SPMs differentially regulate platelet function and may represent a novel class of antiplatelet agents. SPMs also may play an important role in the resolution of inflammation in cardiovascular diseases.

A review of the available clinical therapies for vulvodynia management and new data implicating proinflammatory mediators in pain elicitation.

Localised provoked vulvodynia (LPV) is a common, chronic, and disabling condition: patients experience profound pain and a diminished quality of life. The aetiologic origins of vulvodynia are poorly understood, yet recent evidence suggests a link to site-specific inflammatory responses. Fibroblasts isolated from the vestibule of LPV patients are sensitive to proinflammatory stimuli and copiously produce pain-associated proinflammatory mediators (IL-6 and PGE2 ). Although LPV is a multifactorial disorder, understanding vulvar inflammation and targeting the inflammatory response should lead to treatment advances, especially for patients exhibiting signs of inflammation. NFκB (already targeted clinically) or other inflammatory components may be suitable therapeutic targets. TWEETABLE ABSTRACT: Vulvodynia is a poorly understood, prevalent, and serious women's health issue requiring better understanding to improve therapy.

Ionizing radiation induces myofibroblast differentiation via lactate dehydrogenase.

Pulmonary fibrosis is a common and dose-limiting side-effect of ionizing radiation used to treat cancers of the thoracic region. Few effective therapies are available for this disease. Pulmonary fibrosis is characterized by an accumulation of myofibroblasts and excess deposition of extracellular matrix proteins. Although prior studies have reported that ionizing radiation induces fibroblast to myofibroblast differentiation and collagen production, the mechanism remains unclear. Transforming growth factor-ß (TGF-ß) is a key profibrotic cytokine that drives myofibroblast differentiation and extracellular matrix production. However, its activation and precise role in radiation-induced fibrosis are poorly understood. Recently, we reported that lactate activates latent TGF-ß through a pH-dependent mechanism. Here, we wanted to test the hypothesis that ionizing radiation leads to excessive lactate production via expression of the enzyme lactate dehydrogenase-A (LDHA) to promote myofibroblast differentiation. We found that LDHA expression is increased in human and animal lung tissue exposed to ionizing radiation. We demonstrate that ionizing radiation induces LDHA, lactate production, and extracellular acidification in primary human lung fibroblasts in a dose-dependent manner. We also demonstrate that genetic and pharmacologic inhibition of LDHA protects against radiation-induced myofibroblast differentiation. Furthermore, LDHA inhibition protects from radiation-induced activation of TGF-ß. We propose a profibrotic feed forward loop, in which radiation induces LDHA expression and lactate production, which can lead to further activation of TGF-ß to drive the fibrotic process. These studies support the concept of LDHA as an important therapeutic target in radiation-induced pulmonary fibrosis.

A novel method for overexpression of peroxisome proliferator-activated receptor-γ in megakaryocyte and platelet microparticles achieves transcellular signaling.

BACKGROUND: Microparticles are submicrometer vesicles that contain RNA and protein derived from their parent cells. Platelet and megakaryocyte microparticles represent 80% of circulating microparticles, and their numbers are elevated in diseases such as cancer and type 2 diabetes. The ability of microparticles to transport protein, lipid and RNA to target cells, as a means of transcellular communication, remains poorly understood. Determining the influence that microparticles have on circulating cells is essential for understanding their role in health and in disease. OBJECTIVES: To develop a novel approach to modify the composition of platelet microparticles, and understand how such changes impact their transcellular communication. METHODS: This novel model utilizes a lentiviral technology to alter the transcription factor peroxisome proliferator-activated receptor-γ (PPARγ) content of megakaryoblastic cell lines and primary megakaryocytes, and also the protein composition of generated platelets and microparticles. The subsequent microparticles were isolated and added to target cells for assessment of uptake and resultant signaling events. RESULTS: We successfully engineered microparticles to contain green fluorescent protein and elevated levels of PPARγ. We found that these altered microparticles could be internalized by the monocytic cell line THP-1 and primary human microvascular endothelial cells. Importantly, microparticle-delivered PPARγ was shown to increase the expression of fatty acid-binding protein 4 (FABP4), which is a known PPARγ target gene in THP-1 cells. CONCLUSION: This proof-of-concept modification of megakaryocyte, platelet and microparticle composition and subsequent change in target cell physiology is an important new tool to address transcellular communication of microparticles.

CD40 ligand (CD154) involvement in platelet transfusion reactions.

Platelet transfusions are commonly used treatments that occasionally lead to adverse reactions. Clinical trials, in vitro and animal studies have been performed to try to understand the causes of such reactions. Multiple studies have shown that the supernatant fraction of platelet concentrates contain prothrombotic and pro-inflammatory mediators. The origin of these mediators was first ascribed to white blood cells contaminating the platelet preparation. However, the accumulation of bioactive mediators after leukoreduction focused attention on platelets themselves during storage. Numerous cytokines, chemokines and prostaglandins are released in stored platelet concentrates. We have focused on a powerful mediator called soluble CD40 ligand (sCD40L, formally known as CD154) as a seminal contributor to adverse reactions. sCD40L can bind and signal the surface receptor, CD40, which is present on various types of human cells including white blood cells, vascular cells and fibroblasts. Downstream results of sCD40L/CD40 signaling include pro-inflammatory cytokine and chemokine production, prothrombotic mediator release, adherence and transmigration of leukocytes to endothelium and other undesirable vascular inflammatory events. Increased plasma levels of sCD40L can be detected in conditions such as myocardial infarction, stroke, unstable angina, high cholesterol, or other cardiovascular conditions. In retrospective studies, correlations were made between increased sCD40L levels of platelet concentrates and adverse transfusion reactions. We hypothesize that transfusion of partially activated, CD40L-expressing platelets along with sCD40L into a recipient with damaged or dysfunctional vascular tissue results in a "double-hit", thus inciting inflammation and vascular damage in the recipient.

Electrophilic PPARγ ligands inhibit corneal fibroblast to myofibroblast differentiation in vitro: a potentially novel therapy for corneal scarring.

A critical component of corneal scarring is the TGFß-induced differentiation of corneal keratocytes into myofibroblasts. Inhibitors of this differentiation are potentially therapeutic for corneal scarring. In this study, we tested the relative effectiveness and mechanisms of action of two electrophilic peroxisome proliferator-activated receptor gamma (PPARγ) ligands: cyano-3,12-dioxolean-1,9-dien-28-oic acid-methyl ester (CDDO-Me) and 15-deoxy-Δ(-12,14)-prostaglandin J(2) (15d-PGJ(2)) for inhibiting TGFß-induced myofibroblast differentiation in vitro. TGFß was used to induce myofibroblast differentiation in cultured, primary human corneal fibroblasts. CDDO-Me and 15d-PGJ(2) were added to cultures to test their ability to inhibit this process. Myofibroblast differentiation was assessed by measuring the expression of myofibroblast-specific proteins (αSMA, collagen I, and fibronectin) and mRNA (αSMA and collagen III). The role of PPARγ in the inhibition of myofibroblast differentiation by these agents was tested in genetically and pharmacologically manipulated cells. Finally, we assayed the importance of electrophilicity in the actions of these agents on TGFß-induced αSMA expression via Western blotting and immunofluorescence. Both electrophilic PPARγ ligands (CDDO-Me and 15d-PGJ(2)) potently inhibited TGFß-induced myofibroblast differentiation, but PPARγ was only partially required for inhibition of myofibroblast differentiation by either agent. Electrophilic PPARγ ligands were able to inhibit myofibroblast differentiation more potently than non-electrophilic PPARγ ligands, suggesting an important role of electrophilicity in this process. CDDO-Me and 15d-PGJ(2) are strong inhibitors of TGFß-induced corneal fibroblast to myofibroblast differentiation in vitro, suggesting this class of agents as potential novel therapies for corneal scarring warranting further study in pre-clinical animal models.

Lathyrism-induced alterations in collagen cross-links influence the mechanical properties of bone material without affecting the mineral.

In the present study a rat animal model of lathyrism was employed to decipher whether anatomically confined alterations in collagen cross-links are sufficient to influence the mechanical properties of whole bone. Animal experiments were performed under an ethics committee approved protocol. Sixty-four female (47 day old) rats of equivalent weights were divided into four groups (16 per group): Controls were fed a semi-synthetic diet containing 0.6% calcium and 0.6% phosphorus for 2 or 4 weeks and ß-APN treated animals were fed additionally with ß-aminopropionitrile (0.1% dry weight). At the end of this period the rats in the four groups were sacrificed, and L2-L6 vertebra were collected. Collagen cross-links were determined by both biochemical and spectroscopic (Fourier transform infrared imaging (FTIRI)) analyses. Mineral content and distribution (BMDD) were determined by quantitative backscattered electron imaging (qBEI), and mineral maturity/crystallinity by FTIRI techniques. Micro-CT was used to describe the architectural properties. Mechanical performance of whole bone as well as of bone matrix material was tested by vertebral compression tests and by nano-indentation, respectively. The data of the present study indicate that ß-APN treatment changed whole vertebra properties compared to non-treated rats, including collagen cross-links pattern, trabecular bone volume to tissue ratio and trabecular thickness, which were all decreased (p<0.05). Further, compression tests revealed a significant negative impact of ß-APN treatment on maximal force to failure and energy to failure, while stiffness was not influenced. Bone mineral density distribution (BMDD) was not altered either. At the material level, ß-APN treated rats exhibited increased Pyd/Divalent cross-link ratios in areas confined to a newly formed bone. Moreover, nano-indentation experiments showed that the E-modulus and hardness were reduced only in newly formed bone areas under the influence of ß-APN, despite a similar mineral content. In conclusion the results emphasize the pivotal role of collagen cross-links in the determination of bone quality and mechanical integrity. However, in this rat animal model of lathyrism, the coupled alterations of tissue structural properties make it difficult to weigh the contribution of the anatomically confined material changes to the overall mechanical performance of whole bone. Interestingly, the collagen cross-link ratio in bone forming areas had the same profile as seen in actively bone forming trabecular surfaces in human iliac crest biopsies of osteoporotic patients.

Effect of dietary supplementation with selenium-enriched yeast or sodium selenite on selenium tissue distribution and meat quality in commercial-line turkeys.

The objective of this study was to determine the concentration of total selenium (Se) and proportions of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in the tissues of female turkeys offered diets containing graded additions of selenized-enriched yeast (SY), or sodium selenite (SS). Oxidative stability and tissue glutathione peroxidase (GSH-Px) activity of breast and thigh muscle were assessed at 0 and 10 days post mortem. A total of 216 female turkey poults were enrolled in the study. A total of 24 birds were euthanized at the start of the study and samples of blood, breast, thigh, heart, liver, kidney and gizzard were collected for determination of total Se. Remaining birds were blocked by live weight and randomly allocated to one of four dietary treatments (n = 48 birds/treatment) that differed either in Se source (SY v. SS) or dose (Con [0.2 mg/kg total Se], SY-L and SS-L [0.3 mg/kg total Se as SY and SS, respectively] and SY-H [0.45 mg total Se/kg]). Following 42 and 84 days of treatment 24 birds per treatment were euthanized and samples of blood, breast, thigh, heart, liver, kidney and gizzard were retained for determination of total Se and the proportion of total Se comprised as SeMet or SeCys. Whole blood GSH-Px activity was determined at each time point. Tissue GSH-Px activity and thiobarbituric acid reactive substances were determined in breast and thigh tissue at the end of the study. There were responses (P < 0.001) in all tissues to the graded addition of dietary Se, although rates of accumulation were highest in birds offered SY. There were notable differences between tissue types and treatments in the distribution of SeMet and SeCys, and the activity of tissue and erythrocyte GSH-Px (P < 0.05). SeCys was the predominant form of Se in visceral tissue and SeMet the predominant form in breast tissue. SeCys contents were greater in thigh when compared with breast tissue. Muscle tissue GSH-Px activities mirrored SeCys contents. Despite treatment differences in tissue GSH-Px activity, there were no effects of treatment on any meat quality parameter.

Effects of risedronate on bone marrow adipocytes in postmenopausal women.

SUMMARY: Aminobisphosphonates promote osteoblastogenesis while inhibiting adipogenesis in vitro. Their effect on adipogenesis in vivo remains unknown. In this study, we demonstrate that risedronate prevents marrow fat infiltration in postmenopausal women after 3 years of treatment. INTRODUCTION: Age-related bone loss is associated with high levels of adipogenesis within the bone marrow at the expense of osteoblast population. Bisphosphonates stimulate osteoblastogenesis while inhibiting adipogenesis in vitro. In the present study, we tested whether the effect of bisphosphonates on marrow adipogenesis in vitro is also seen in vivo. METHODS: We analyzed transiliac bone biopsies from a randomized, placebo-controlled clinical trial that evaluated the effects of risedronate treatment 5 mg/day on vertebral and non-vertebral fractures in women with postmenopausal osteoporosis. Paired bone biopsies were obtained from a subset of patients at baseline and after treatment with placebo or risedronate for 3 years (n = 14 per group). Biopsies were stained with toluidine blue and hematoxylin/eosin. Adipocyte volume/tissue volume (AV/TV), mean adipocyte number (AD(#)), and mean adipocyte diameter (AD(diam)) were quantified. Finally, expression levels of the adipogenesis transcription factor peroxisome proliferator activator gamma 2 (PPARγ2) within the bone marrow were quantified using immunohistochemistry. RESULTS: In the placebo group, AV/TV, AD(#), and AD(diam) significantly increased after 3 years (~15%, p < 0.01). In contrast, AD(diam) remained unchanged and AV/TV and AD(#) were significantly reduced (~20%) in the risedronate group at 3 years (p < 0.01). These changes were associated with a significant reduction in PPARγ2 expression in the bone marrow of risedronate-treated women. CONCLUSIONS: Risedronate reduces bone marrow fat in postmenopausal women. These findings are the first demonstration of an effect of bisphosphonates on marrow fat in humans in vivo. By regulating the amount of fat within the bone marrow, this effect may contribute to the beneficial effect of bisphosphonates on bone mass.

Effect of risedronate on osteocyte viability and bone turnover in paired iliac bone biopsies from early postmenopausal women.

It is unclear whether standard clinical doses of risedronate affect osteocyte viability. This study examined osteocyte viability and bone remodeling rate in early postmenopausal women (1-5 years after menopause) who were treated with a standard clinical dose of risedronate (5 mg/day, orally) for 1 year. Paired transiliac bone biopsies were obtained from 19 postmenopausal women at baseline and after 1-year treatment with placebo (n = 8, mean age 52.9 ± 3.4 years) or risedronate 5 mg/day (n = 11, mean age 52.5 ± 3.4 years). In these samples, we measured osteocyte- and bone remodeling-related variables in trabecular bone. In both the placebo and risedronate groups, empty lacunae were significantly decreased after 1-year treatment compared to baseline. There were no significant differences in osteocyte-related variables between placebo and risedronate. Risedronate significantly reduced bone-remodeling indices including mineralizing surface (MS/BS), bone formation rate (BFR/BS), and activation frequency (Ac.f). Risedronate treatment caused significantly lower MS/BS and Ac.f than placebo administration. In conclusion, risedronate 5 mg/day effectively inhibited bone remodeling but did not significantly reduce osteocyte viability in trabecular bone.

Anticancer Role of PPARgamma Agonists in Hematological Malignancies Found in the Vasculature, Marrow, and Eyes.

The use of targeted cancer therapies in combination with conventional chemotherapeutic agents and/or radiation treatment has increased overall survival of cancer patients. However, longer survival is accompanied by increased incidence of comorbidities due, in part, to drug side effects and toxicities. It is well accepted that inflammation and tumorigenesis are linked. Because peroxisome proliferator-activated receptor (PPAR)-gamma agonists are potent mediators of anti-inflammatory responses, it was a logical extension to examine the role of PPARgamma agonists in the treatment and prevention of cancer. This paper has two objectives: first to highlight the potential uses for PPARgamma agonists in anticancer therapy with special emphasis on their role when used as adjuvant or combined therapy in the treatment of hematological malignancies found in the vasculature, marrow, and eyes, and second, to review the potential role PPARgamma and/or its ligands may have in modulating cancer-associated angiogenesis and tumor-stromal microenvironment crosstalk in bone marrow.

Differences between bisphosphonates in binding affinities for hydroxyapatite.

Bisphosphonates (BPs) inhibit bone resorption and are widely used for the treatment of bone diseases, including osteoporosis. BPs are also being studied for their effects on hydroxyapatite (HAP)-containing biomaterials. There is a growing appreciation that there are hitherto unexpected differences among BPs in their mineral binding affinities that affect their pharmacological and biological properties. To study these differences, we have developed a method based on fast performance liquid chromatography using columns of HAP to which BPs and other phosphate-containing compounds can adsorb and be eluted by using phosphate buffer gradients at pH 6.8. The individual compounds emerge as discrete and reproducible peaks for a range of compounds with different affinities. For example, the peak retention times (min; mean +/- SEM) were 22.0 +/- 0.3 for zoledronate, 16.16 +/- 0.44 for risedronate, and 9.0 +/- 0.28 for its phosphonocarboxylate analog, NE10790. These results suggest that there are substantial differences among BPs in their binding to HAP. These differences may be exploited in the development of biomaterials and may also partly explain the extent of their relative skeletal retention and persistence of biological effects observed in both animal and clinical studies.

Bone matrix quality and plasma homocysteine levels.

It has recently been reported in the clinical literature that blood homocysteine levels correlate well with fracture risk, although a couple of reports exist to the opposite. Bone strength depends on both bone quantity and quality. The purpose of the present study was to investigate possible correlations between plasma homocysteine levels and bone material properties (Bone Mineral Density Distribution; BMDD, and collagen cross-link ratio). In the present study, femoral heads from subjects (N=19, females, age range 70-95 years old) with known homocysteine plasma levels were investigated. The bone material was collected during hemiarthroplasty surgery. We have determined collagen cross-link ratio and bone mineralization density distribution (BMDD) in bone tissue from patients with acute femoral neck fractures, by Fourier Transform Infrared Imaging (FTIRI) and quantitative Backscattered Electron Imaging (qBEI), respectively. The collagen cross-link ratio that was spectroscopically determined was pyridinoline/divalent cross-links (pyr/divalent). The BMDD variables quantified were: CaMean: the weighted mean calcium concentration; CaPeak: the most frequent Ca concentration; CaWidth: the width of the distribution, a measure of the mineralization homogeneity; CaLow: the percentage of bone area that is mineralized below the 5th percentile in the reference range; CaHigh: the percentage of bone area that is mineralized above the 95th percentile in the reference range. There was a significant correlation between plasma homocysteine levels and collagen cross-link ratio in areas of primary mineralized bone (p<0.0001), unlike the case of trabecular bone surfaces undergoing resorption (p>0.05). On the other hand there was no correlation in any of the BMDD parameters and plasma homocysteine levels (p>0.05). The results are consistent with the known effect of homocysteine on collagen post-translational modifications. These changes were independent of bone mineral characteristics. The results of the present study offer a mechanism by which homocysteine affects bone quality, but caution should be exercised since all patients examined had sustained fracture.

15-deoxy-Delta12,14 prostaglandin J2-induced heme oxygenase-1 in megakaryocytes regulates thrombopoiesis.

BACKGROUND: Platelet production is an intricate process that is poorly understood. Recently, we demonstrated that the natural peroxisome proliferator-activated receptor gamma (PPARgamma) ligand, 15-deoxy-Delta(12,14) prostaglandin J(2) (15d-PGJ(2)), augments platelet numbers by increasing platelet release from megakaryocytes through the induction of reactive oxygen species (ROS). 15d-PGJ(2) can exert effects independent of PPARgamma, such as increasing oxidative stress. Heme oxygenase-1 (HO-1) is a potent antioxidant and may influence platelet production. OBJECTIVES: To further investigate the influence of 15d-PGJ(2) on megakaryocytes and to understand whether HO-1 plays a role in platelet production. METHODS: Meg-01 cells (a primary megakaryoblastic cell line) and primary human megakaryocytes derived from cord blood were used to examine the effects of 15d-PGJ(2) on HO-1 expression in megakaryocytes and their daughter platelets. The role of HO-1 activity in thrombopoiesis was studied using established in vitro models of platelet production. RESULTS AND CONCLUSIONS: 15d-PGJ(2) potently induced HO-1 protein expression in Meg-01 cells and primary human megakaryocytes. The platelets produced from these megakaryocytes also expressed elevated levels of HO-1. 15d-PGJ(2)-induced HO-1 was independent of PPARgamma, but could be replicated using other electrophilic prostaglandins, suggesting that the electrophilic properties of 15d-PGJ(2) were important for HO-1 induction. Interestingly, inhibiting HO-1 activity enhanced ROS generation and augmented 15d-PGJ(2)-induced platelet production, which could be attenuated by antioxidants. These new data reveal that HO-1 negatively regulates thrombopoiesis by inhibiting ROS.

Changes in non-enzymatic glycation and its association with altered mechanical properties following 1-year treatment with risedronate or alendronate.

SUMMARY: One year of high-dose bisphosphonate (BPs) therapy in dogs allowed the increased accumulation of advanced glycation end-products (AGEs) and reduced postyield work-to-fracture of the cortical bone matrix. The increased accumulation of AGEs in these tissues may help explain altered bone matrix quality due to the administration of BPs in animal models INTRODUCTION: Non-enzymatic glycation (NEG) is a posttranslational modification of the organic matrix that results in the formation of advanced glycation end-products (AGEs). In bone, the accumulation of AGEs play an important role in determining fracture resistance, and elevated levels of AGEs have been shown to adversely affect the bone's propensity to brittle fracture. It was thus hypothesized that the suppression of tissue turnover in cortical bone due to the administration of bisphosphonates would cause increased accumulation of AGEs and result in a more brittle bone matrix. METHODS: Using a canine animal model (n = 12), we administered daily doses of a saline vehicle (VEH), alendronate (ALN 0.20, 1.00 mg/kg) or risedronate (RIS 0.10, 0.50 mg/kg). After a 1-year treatment, the mechanical properties, intracortical bone turnover, and the degree of nonenzymatic cross-linking of the organic matrix were measured from the tibial cortical bone tissue of these animals. RESULTS: There was a significant accumulation of AGEs at high treatment doses (+49 to + 86%; p < 0.001), but not at doses equivalent to those used for the treatment of postmenopausal osteoporosis, compared to vehicle. Likewise, postyield work-to-fracture of the tissue was significantly reduced at these high doses (-28% to -51%; p < 0.001) compared to VEH. AGE accumulation inversely correlated with postyield work-to-fracture (r (2) = 0.45; p < 0.001), suggesting that increased AGEs may contribute to a more brittle bone matrix. CONCLUSION: High doses of bisphosphonates result in the accumulation of AGEs and a reduction in energy absorption of cortical bone. The increased accumulation of AGEs in these tissues may help explain altered bone matrix quality due to the administration of BPs in animal models.

Short communication: effects of 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester on milk production and composition of lactating Holstein dairy cows.

Sixteen multiparous Holstein cows were used to determine the effects of 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester (HMBi: 0 vs. 1.26 g/kg of total ration dry matter (DM) and dietary crude protein (CP) concentration [14.7% (low) vs. 16.9% (standard), DM basis] on milk yield and composition using a replicated 4 x 4 Latin square design experiment with 4-wk periods. Cows were fed ad libitum a total mixed ration with a 1:1 forage-to-concentrate ratio (DM basis), and diets provided an estimated 6.71 and 1.86% lysine and methionine, respectively, in metabolizable protein for the low-protein diet and 6.74 and 1.82% in the standard protein diet. Dry matter intake, milk yield, and composition were measured during wk 4 of each period. There were no effects on DM intake, which averaged 24.7 kg/d. There was an interaction between dietary CP and HMBi for milk yield and 3.5% fat-corrected milk (FCM). Feeding HMBi decreased milk and FCM yield when fed with the low-CP diet but did not affect milk or FCM yield when fed with the standard CP diet. Feeding HMBi increased milk protein concentration regardless of diet CP concentration and increased milk protein yield when added to the standard CP diet but not the low-CP diet. The positive effect of HMBi on milk protein yield was only observed at the standard level of dietary CP, suggesting other factors limited the response to HMBi when dietary protein supply was restricted.

Targeting cyclooxygenase-2 in hematological malignancies: rationale and promise.

There is much interest in the potential use of Cox-2 selective inhibitors in combination with other cancer therapeutics. Malignancies of hematopoietic and non-hematopoietic origin often have increased expression of cyclooxygenase-2 (Cox-2), a key modulator of inflammation. For example, hematological malignancies such as chronic lymphocytic leukemia, chronic myeloid leukemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma and multiple myeloma often highly express Cox-2, which correlates with poor patient prognosis. Expression of Cox-2 enhances survival and proliferation of malignant cells, while negatively influencing anti-tumor immunity. Hematological malignancies expressing elevated levels of Cox-2 potentially avoid immune responses by producing factors that enhance angiogenesis and metastasis. Cellular immune responses regulated by natural killer cells, cytotoxic T lymphocytes, and T regulatory cells are also influenced by Cox-2 expression. Therefore, Cox-2 selective inhibitors have promising therapeutic potential in patients suffering from certain hematological malignancies.