Effects of obesity on bone metabolism

Obesity is traditionally viewed to be beneficial to bone health because of well-established positive effect of mechanical loading conferred by body weight on bone formation, despite being a risk factor for many other chronic health disorders. Although body mass has a positive effect on bone formation, whether the mass derived from an obesity condition or excessive fat accumulation is beneficial to bone remains controversial. The underline pathophysiological relationship between obesity and bone is complex and continues to be an active research area. Recent data from epidemiological and animal studies strongly support that fat accumulation is detrimental to bone mass. To our knowledge, obesity possibly affects bone metabolism through several mechanisms. Because both adipocytes and osteoblasts are derived from a common multipotential mesenchymal stem cell, obesity may increase adipocyte differentiation and fat accumulation while decrease osteoblast differentiation and bone formation. Obesity is associated with chronic inflammation. The increased circulating and tissue proinflammatory cytokines in obesity may promote osteoclast activity and bone resorption through modifying the receptor activator of NF-κB (RANK)/RANK ligand/osteoprotegerin pathway. Furthermore, the excessive secretion of leptin and/or decreased production of adiponectin by adipocytes in obesity may either directly affect bone formation or indirectly affect bone resorption through up-regulated proinflammatory cytokine production. Finally, high-fat intake may interfere with intestinal calcium absorption and therefore decrease calcium availability for bone formation. Unraveling the relationship between fat and bone metabolism at molecular level may help us to develop therapeutic agents to prevent or treat both obesity and osteoporosis

Virtual Interaction for Effective E-Learning

This research investigates whether information technologies, such as automated question answering (QA), can add interactivity into a multimedia-based e-learning system, as well as how this type of virtual interaction affects the effectiveness of e-learning. Based on a review of multiple learning theories and technologies, an exploratory model for studying the effectiveness of interactive e-learning, Learning with Virtual Mentors (LVM), is proposed and a prototype system is developed to implement the LVM model. A series of studies, including a controlled experiment and surveys, have been conducted to explore the relationships among the core constructs of the LVM model: learning phases, system interactivity, learning activity, and learning outcomes. Findings indicate that virtual interaction positively impacts student behaviors by encouraging students to interact more and increasing student satisfaction with the learning process; however, the correlation between virtual interaction and actual learning performance is limited. Consequently, the LVM model needs to be further explored and developed

Can the shape of a planar pathway be estimated using proximal forces of inserting a flexible shaft?

The shape information of flexible endoscopes or other continuum structures, e.g., intro-vascular catheters, is needed for accurate navigation, motion compensation, and haptic feedback in robotic surgical systems. Existing methods rely on optical fiber sensors, electromagnetic sensors, or expensive medical imaging modalities such as X-ray fluoroscopy, magnetic resonance imaging, and ultrasound to obtain the shape information of these flexible medical devices. Here, we propose to estimate the shape/curvature of a continuum structure by measuring the force required to insert a flexible shaft into the internal channel/pathway of the continuum. We found that there is a consistent correlation between the measured insertion force and curvature of the planar continuum pathway. A testbed was built to insert a flexible shaft into a planar continuum pathway with adjustable shapes. The insertion forces, insertion displacement, and the shapes of the pathway were recorded. A neural network model was developed to model this correlation based on the training data collected on the testbed. The trained model, tested on the testing data, can accurately estimate the curvature magnitudes and the accumulated bending angles of the pathway simply based on the measured insertion force at the proximal end of the shaft. The approach may be used to estimate the curvature magnitudes and accumulated bending angles of flexible endoscopic surgical robots or catheters for accurate motion compensation, haptic force feedback, localization, or navigation. The advantage of this approach is that the employed proximal force can be easily obtained outside the pathway or continuum structure without any embedded sensor in the continuum structure. Future work is needed to further investigate the correlation between insertion forces and the pathway and enhance the capability of the model in estimating more complex shapes, e.g., spatial shapes with multiple bends

Vitamin C Prevents Hypogonadal Bone Loss

Epidemiologic studies correlate low vitamin C intake with bone loss. The genetic deletion of enzymes involved in de novo vitamin C synthesis in mice, likewise, causes severe osteoporosis. However, very few studies have evaluated a protective role of this dietary supplement on the skeleton. Here, we show that the ingestion of vitamin C prevents the low-turnover bone loss following ovariectomy in mice. We show that this prevention in areal bone mineral density and micro-CT parameters results from the stimulation of bone formation, demonstrable in vivo by histomorphometry, bone marker measurements, and quantitative PCR. Notably, the reductions in the bone formation rate, plasma osteocalcin levels, and ex vivo osteoblast gene expression 8 weeks post-ovariectomy are all returned to levels of sham-operated controls. The study establishes vitamin C as a skeletal anabolic agent. © 2012 Zhu et al

An essential role for Stat3 in regulating IgG immune complex‐induced pulmonary inflammation

Growing evidence suggests that transcription factor signal transducer and activator of transcription (Stat) 3 may play an important regulatory role during inflammation. However, the function of Stat3 in acute lung injury (ALI) is largely unknown. In the current study, by using an adenoviral vector expressing a dominant‐negative Stat3 isoform (Ad‐Stat3‐EVA), we determined the role of Stat3 in IgG immune complex (IC)‐induced inflammatory responses and injury in the lung from C57BL/6J mice. We show that IgG IC‐induced DNA binding activity of Stat3 in the lung was significantly inhibited by Stat3‐EVA. We demonstrate that both lung vascular permeability (albumin leak) and lung myeloperoxidase accumulation in the Ad‐Stat‐EVA treated mice were substantially reduced when compared with values in mice receiving control virus (Ad‐GFP) during the injury. Furthermore, intratracheal administration of Ad‐Stat3‐EVA caused significant decreases in the contents of neutrophils, inflammatory cytokines (TNF‐α and IL‐6), chemokines [keratinocyte cell‐derived chemokine, macrophage inflammatory protein (MIP)‐1α, and MIP‐1β], and complement component C5a in bronchoalveolar lavage fluids. Using Stat3‐specific small interfering RNA, we show that knocking down Stat3 expression in alveolar macrophages (MH‐S cells) significantly reduced the production of proinflammatory mediators on IgG IC stimulation. These data suggest that Stat3 plays an essential role in the pathogenesis of IgG IC‐induced ALI by mediating the acute inflammatory responses in the lung and alveolar macrophages.—Tang, H., Yan, C., Cao, J., Sarma, J. V., Haura, E. B., Wu, M., Gao, H. An essential role for Stat3 in regulating IgG immune complex‐induced pulmonary inflammation. FASEB J. 25, 4292–4300 (2011). www.fasebj.orgPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154500/1/fsb2fj11187955.pd