EphB4 enhances the process of endochondral ossification and inhibits remodeling during bone fracture repair

Previous reports have identified a role for the tyrosine kinase receptor EphB4 and its ligand, ephrinB2, as potential mediators of both bone formation by osteoblasts and bone resorption by osteoclasts. In the present study, we examined the role of EphB4 during bone repair after traumatic injury. We performed femoral fractures with internal fixation in transgenic mice that overexpress EphB4 under the collagen type 1 promoter (Col1‐EphB4) and investigated the bone repair process up to 12 weeks postfracture. The data indicated that Col1‐EphB4 mice exhibited stiffer and stronger bones after fracture compared with wild‐type mice. The fractured bones of Col1‐EphB4 transgenic mice displayed significantly greater tissue and bone volume 2 weeks postfracture compared with that of wild‐type mice. These findings correlated with increased chondrogenesis and mineral formation within the callus site at 2 weeks postfracture, as demonstrated by increased safranin O and von Kossa staining, respectively. Interestingly, Col1‐EphB4 mice were found to possess significantly greater numbers of clonogenic mesenchymal stromal progenitor cells (CFU‐F), with an increased capacity to form mineralized nodules in vitro under osteogenic conditions, when compared with those of the wild‐type control mice. Furthermore, Col1‐EphB4 mice had significantly lower numbers of TRAP‐positive multinucleated osteoclasts within the callus site. Taken together, these observations suggest that EphB4 promotes endochondral ossification while inhibiting osteoclast development during callus formation and may represent a novel drug target for the repair of fractured bones. © 2013 American Society for Bone and Mineral Research.     

Early inhibition of the renin‐angiotensin system improves the long‐term graft survival of single pediatric donor kidneys transplanted in adult recipients

Transplanting single pediatric donor kidneys into adult recipients has an increased risk of hyperfiltration injury and graft loss. It is unknown if renin‐angiotensin system (RAS) blockers are beneficial in this setting. We retrospectively analyzed 94 adults who received single kidneys from donors <10 years old during 1996–2009. The recipients were divided into group 1 with RAS blockers (n = 40) and group 2 without RAS blockers (n = 54) in the first year of transplant. There was no significant difference in any donor/recipient demographic between the two groups. Graft function, incidence of delayed graft function, acute rejection, and persistent proteinuria were not statistically different either. Kaplan–Meier estimated death‐censored graft survivals were significantly better in group 1 than in group 2: 95 vs. 81.2%, 82.4 vs. 61.2%, 72.6 vs. 58.5%, and 68.5 vs. 47.2% at 1, 3, 5, and 7 years, respectively (log rank P = 0.043). Multivariable analysis found persistent proteinuria was a risk factor for graft loss (OR 2.70, 95% CI 1.33–5.49, P = 0.006), while RAS blockers reduced the risk of graft loss (OR 0.38, 95% CI 0.18–0.79, P = 0.009). Early RAS blockade therapy in the first year of transplant is associated with superior long‐term graft survival among adults transplanted with single pediatric donor kidneys.     

Burdens and Psychological Health of Family Caregivers of People with Schizophrenia in Two Chinese Metropolitan Cities: Hong Kong and Guangzhou

Family members charged with the care of those suffering from schizophrenia experience considerable stress due to their multiple responsibilities. Research regarding the burdens of caregiving is scant in Hong Kong and China. The present study quantified the association of the duties of caregivers with mental health symptoms in two Asian cities having distinct health care systems (i.e., Hong Kong and Guangzhou, China). Thirty nine caregivers in Hong Kong and 70 caregivers in Guangzhou were recruited from nongovernmental mental health organizations. They were assessed using the Chinese version of the Involvement Evaluation Questionnaire and the General Health Questionnaire. While the Guangzhou family caregivers had a significantly higher burden than the Hong Kong sample, there was no significant difference in the psychological health status of family caregivers in the two cities. Result of correlational analyses, however, revealed high associations between burden of care variables and the psychological health of the caregivers. Findings for the present study have implications regarding the physical and mental health needs of those caring for seriously disturbed relatives.     

Nucleoside triphosphates inhibit ADP,collagen, and epinephrine-induced platelet aggregation: Role of P2Y1 and P2Y12 receptors

Background

Platelets express two ADP receptors namely P2Y₁ and P2Y₁₂ that regulate ADP and other agonists-induced platelet aggregation. P2Y₁ receptor activation causes platelet shape change while P2Y₁₂ receptor activation induces platelet aggregation. Previously, anti-aggregatory effects of ATP on ADP-induced and pro-aggregatory effects on epinephrine-induced platelet aggregation have been reported. However, the effects of other nucleoside triphosphates on platelet aggregation have never been described. The aim of the present study was to characterise the effects of nucleoside triphosphates (ATP, UTP, GTP, and CTP) on agonist-induced platelet aggregation.

Methods

The experiments were performed on platelet rich plasma freshly isolated from blood donated by healthy human volunteers.

Results

All the nucleoside triphosphates tested inhibited ADP- and collagen-induced platelet aggregation in a concentration-dependent manner with a rank order of potency, 2MeSATP > ATP ≥ α,β,methyleneATP > UTP  >> CTP ≥ GTP. The IC₅₀ values against ADP (10 μM)-induced platelet aggregation were 0.039 ± 0.013, 18 ± 7, 25 ± 6, 32 ± 9, 360 ± 130, and 400 ± 160 μM, respectively. Low concentrations of ATP induced platelet shape change which was due to contaminating ADP. However, higher concentrations antagonised ADP and MRS2365-induced platelet shape change. The ATP analogue α,β,methyleneATP and CTP but not UTP and GTP also antagonised ADP-induced platelet shape change. Similarly, low ATP concentrations potentiated epinephrine-induced platelet aggregation that was abolished by P2Y₁ antagonist MRS2500 suggesting P2Y₁ receptor activation due to contaminating ADP. Higher ATP concentrations, α,β,methyleneATP, UTP, CTP, and GTP antagonised epinephrine-induced platelet aggregation.

Conclusion

Thus, the data demonstrate nucleoside triphosphates in general act as P2Y₁₂ receptor antagonists and antagonise ADP-, collagen-, and epinephrine-induced platelet aggregation.     

Onchocerca volvulus-specific antibody and cytokine responses in onchocerciasis patients after 16 years of repeated ivermectin therapy

The recommended control option against onchocerciasis is repeated ivermectin treatment, which will need to be implemented for decades, and it remains unknown how repeated ivermectin therapy might affect immunity against Onchocerca volvulus in the long term. O. volvulus-specific antibody reactivity and cellular cytokine production were investigated in onchocerciasis patients receiving ivermectin (150 microg/kg) annually for 16 years. In treated patients, the T helper type 2 (Th2) cytokine interleukin (IL)-5 and T regulatory IL-10 in response to O. volvulus antigen (OvAg) and bacteria-derived Streptolysin O (SL-O) diminished to levels found in infection-free endemic controls; also, cellular release of Th1-type interferon (IFN)-gamma at 16 years post initial ivermectin treatment (p.i.t.) approached control levels. In ivermectin-treated onchocerciasis patients, IL-5 production in responses to the mitogen phytohaemagglutinin (PHA) decreased, but IL-10 in response PHA increased, and neither attained the cytokine production levels of endemic controls. At 16 years p.i.t., O. volvulus-specific IgG1 and IgG4 subclass reactivity still persisted at higher levels in onchocerciasis patients than in O. volvulus exposed but microfilariae-free endemic controls. In addition, cytokine responses remained depressed in onchocerciasis patients infected concurrently with Mansonella perstans and Necator americanus or Entamoeba histolytica/dispar. Thus, long-term ivermectin therapy of onchocerciasis may not suffice to re-establish fully a balanced Th1 and Th2 immune responsiveness in O. volvulus microfilariae-negative individuals. Such deficient reconstitution of immune competence may be due to an as yet continuing and uncontrolled reinfection with O. volvulus, but parasite co-infections can also bias and may prevent the development of such immunity.