Central (hypothalamic) control of bone mass is proposed to be mediated through beta2-adrenergic receptors (beta2-ARs). While investigations in mouse bone cells suggest that epinephrine enhances both RANKL and OPG mRNA via both beta-ARs and alpha-ARs, whether alpha-ARs are expressed in human bone cells is controversial. The current study investigated the expression of alpha1-AR and beta2-AR mRNA and protein and the functional role of adrenergic stimulation in human osteoblasts (HOBs). Expression of alpha1B- and beta2-ARs was examined by RT-PCR, immunofluorescence microscopy and Western blot (for alpha1B-ARs). Proliferation in HOBs was assessed by (3)H-thymidine incorporation and expression of RANKL and OPG was determined by quantitative RT-PCR. RNA message for alpha1B- and beta2-ARs was expressed in HOBs and MG63 human osteosarcoma cells. alpha1B- and beta2-AR immunofluorescent localization in HOBs was shown for the first time by deconvolution microscopy. alpha1B-AR protein was identified in HOBs by Western blot. Both alpha1-agonists and propranolol (beta-blocker) increased HOB replication but fenoterol, a beta2-agonist, inhibited it. Fenoterol nearly doubled RANKL mRNA and this was inhibited by propranolol. The alpha1-agonist cirazoline increased OPG mRNA and this increase was abolished by siRNA knockdown of alpha1B-ARs in HOBs. These data indicate that both alpha1-ARs and beta2-ARs are present and functional in HOBs. In addition to beta2-ARs, alpha1-ARs in human bone cells may play a role in modulation of bone turnover by the sympathetic nervous system.

Using human peripheral blood mononuclear cells as osteoclast precursors, we showed that dexamethasone stimulated osteoclast generation at a pharmacological concentration but did not affect the life span of human osteoclasts. Dexamethasone also dose-dependently increased signals for osteoclastogenesis.Introduction: Glucocorticoid-induced osteoporosis is a common and serious disease. Glucocorticoids predominantly affect osteoblast proliferation and life span. Much of the bone loss is caused by reduced bone formation, but there is also an element of increased bone resorption. Materials and Methods: Human peripheral blood mononuclear cells were cultured on whale dentine and induced to differentiate to osteoclasts by RANKL and human macrophage-colony stimulating factor (M-CSF). Osteoclast activity was quantified by pit area. RANKL and osteoprotegerin (OPG) expression in osteoblasts were measured by real-time RT-PCR. Results: In the early phase of osteoclast generation (0-16 days), cultures from two different donors showed that dexamethasone at 10 −8 M increased pit area by 2.5-fold, whereas lower concentrations had no effect. At the highest dexamethasone concentration (10 −7 M), pit area was reduced. In 21-day cultures from three other donors, a similar increase was seen with dexamethasone at 10 −8 M. There was, however, no evidence of increased life span of osteoclasts with dexamethasone. In human primary osteoblasts, dexamethasone dosedependently reduced OPG and increased RANKL expression as measured by quantitative real time RT-PCR. Conclusion: These data provide some explanation at a cellular and molecular level for the observed increase in bone resorption seen in patients treated with glucocorticoids and indicate that there are clear direct effects of glucocorticoids on bone resorption in human cell systems that may differ from other species.

As part of curriculum renewal in three introductory chemistry courses at the University of Sydney, a partially flipped classroom model was implemented. Content that is conventionally delivered in the in-class sessions was moved online through the use of web-based tutorials, videos and quizzes. During the in-class sessions, active learning opportunities were created through the use of guided-inquiry worksheets and clicker responses to promote peer-to-peer and instructor-led discussion. Student evaluations indicated high satisfaction with the quality of teaching and learning resources. In comparison to before these changes, there was a statistically significant increase in the number of students achieving the higher grades across all three courses. Failure rates decreased or remained unchanged. The course with the historically highest attrition showed a marked improvement. These results suggest that a partially flipped learning model can be useful to enhance student engagement, support learning, and positively impact on retention and academic performance.

1. Static exposure of rainbow trout, Oncorhynchus mykiss, to three commercial 14C-labelled cationic polymers (EDP, epichlorhydrin-dimethylamine; CYT, polyacrylamide ester; and STK, polyacrylamide amide) resulted in 14C being concentrated only in gill tissue. 2. Depuration studies examining the effect of humic acid (HA) on cationic polymer bound in gill tissue indicate that the binding is reversible with exposure to polymer-free water and polymer-free water with HA for each of the three polymers. 3. Analysis of blood pH, Na+, K+, total NH3 and Cl- after static water exposures to EDP (m.w. 50,000) at 7.5 mg EDP/l revealed a treatment related decrease in blood pH, from 7.1 to 6.6, accompanied by an increase in blood NH3 and evidence of severe impairment of ion regulation. 4. Repeated exposure to the cationic polymers did not result in increases in the 14C concentration in gill tissue suggesting that bioaccumulation of the polymers does not occur. 5. These data suggest that the gill is the site of toxicity for these cationic polymers and that their toxic effects involve gill function and ion regulation rather than systemic actions on internal organs.