Bone mineral content is positively correlated to n-3 fatty acids in the femur of growing rats.

The present study was conducted to determine whether provision of preformed dietary docosapentaenoic acid (DPAn-6) can replace DHA for normal long bone growth as assessed by dual-energy X-ray absorptiometry for mineral content (BMC). A newly modified artificial rearing method was employed to generate n-3 fatty acid-deficient rats. Except the dam-reared (DR; 3.1 % alpha-linolenic acid) group, newborn pups were separated from their mothers at age 2 d and given artificial rat milk containing linoleic acid (LA), or LA supplemented with 1 % DHA (22 : 6n-3; DHA), 1 % DPAn-6 (DPA), or 1 % DHA plus 0.4 % DPAn-6 (DHA/DPA). The rats were later weaned onto similar pelleted diets. At adulthood, the rats were euthanised and bones (femur, tibia, and lumbar vertebrae) collected for tissue fatty acid analysis and bone mineral density (BMD) determination. The analyses showed that long bones such as femur and tibia in DPAn-6-treated rats contained higher DPAn-6 content and generally had the lowest BMC and BMD values. Hence, DPAn-6 did not replace DHA for normal bone growth and maximal BMC in femur, indicating an indispensible role of DHA in bone health. In conclusion, DHA accumulates in the osteoblast-rich and nerve-abundant periosteum of femur; DHA but not EPA appears to be a vital constituent of marrow and periosteum of healthy modelling bone; and both DHA and total n-3 PUFA strongly correlate to BMC.

Calcimimetic inhibits late-stage cyst growth in ADPKD.

In polycystic kidney disease (PKD), genetic mutations in polycystin 1 and 2 lead to defective intracellular trafficking of calcium, thereby decreasing intracellular calcium and altering cAMP signaling to favor proliferation. We hypothesized that calcimimetics, allosteric modulators of the calcium-sensing receptor, would reduce cyst growth by increasing intracellular calcium. We randomly assigned 20-wk-old male rats with a form of autosomal dominant PKD (heterozygote Cy/+) to one of four groups for 14 to 18 wk of treatment: (group 1) no treatment; (group 2) calcimimetic R-568 formulated in the diet; (group 3) R-568 plus calcium-supplemented drinking water (R-568 plus Ca); or (group 4) Ca-supplemented drinking water with a normal diet (Ca). Severity of PKD did not progress in any of the three treatment groups between 34 and 38 wk. Compared with no treatment, cyst growth was unaffected at 34 wk by all treatments, but cyst volume and fibrosis were lower at 38 wk, with both R-568-treated groups demonstrating a greater reduction than calcium alone. Between 34 and 38 wk, the total kidney weight increased by 78% in the control group (P < 0.001) and by 19% in the Ca group (P < 0.01), but did not increase in the R-568 or R-568 plus Ca groups, suggesting inhibition of disease progression despite equivalent suppression of parathyroid hormone. In summary, treatment of hyperparathyroidism halts late-stage progression of rodent cystic kidney disease. The benefit of R-568 alone suggests calcium-sensing receptor modulation may have additional inhibitory effects on late-stage cyst growth resulting from a direct modulation of intracellular calcium.

A rat model of chronic kidney disease-mineral bone disorder.

Chronic Kidney Disease-Mineral Bone Disorder (CKD-MBD) is a newly defined syndrome encompassing patients with chronic kidney disease that have a triad of biochemical alterations in calcium, phosphorus and parathyroid hormone, vascular calcification, and bone abnormalities. Here we describe a novel Cy/+ rat model of slowly progressive kidney disease spontaneously developing the three components of CKD-MBD when fed a normal phosphorus diet. Since the renal disorder progressed 'naturally' we studied the effect of dietary manipulation during the course of the disease. Animals with early, but established, chronic kidney disease were fed a casein-based or a grain-based protein diet both of which had equivalent total phosphorus contents. The two different sources of dietary protein had profound effects on the progression of CKD-MBD, likely due to differences in intestinal bioavailability of phosphorus. Although both dietary treatments resulted in the same serum phosphorous levels, the casein-fed animals had increased urinary phosphorus excretion and elevated serum FGF23 compared to the grain-fed rats. This model should help identify early changes in the course of chronic kidney disease that may lead to CKD-MBD.

R-568 reduces ectopic calcification in a rat model of chronic kidney disease-mineral bone disorder (CKD-MBD).

BACKGROUND: Chronic kidney disease-mineral bone disorder (CKD-MBD), a newly defined disorder in patients with CKD, describes the interacting triad of (1) biochemical abnormalities of calcium, phosphorus and parathyroid hormone (PTH), (2) extraskeletal calcification and (3) abnormal bone. METHODS: We studied the effects of the calcimimetic R-568, R-568 with calcium (R-568 + Ca) or calcium (Ca) alone compared with control CKD rats on this triad in the Cy/+ male rat, a model of progressive CKD that spontaneously develops CKD-MBD on a normal phosphorus diet. Animals were treated for either 14 or 18 weeks beginning at 20 weeks of age (34-week and 38-week animals, respectively). RESULTS: The results demonstrated similar efficacy of R-568, R-568 + Ca and Ca in lowering PTH levels. R-568 alone lowered plasma calcium compared to control over time, but increased phosphorus compared to control early in the course of the disease, but not at 38 weeks. Animals treated with Ca alone or R-568 + Ca had lower phosphorus levels; the Ca alone group had elevated Ca levels. Bone volume improved in the calcium-treated groups. In contrast, arterial and cardiac calcification worsened by most assessments in the R-568 + Ca and Ca alone treated animals compared with R-568 alone whereas R-568 alone treatment showed beneficial effects on most sites of extraskeletal calcification. CONCLUSION: Thus, R-568, with or without Ca, improved the biochemical abnormalities of hyperparathyroidism but with higher and lower calcium levels, respectively, compared with controls. However, R-568 + Ca had more dramatic improvement in bone volume, but more extraskeletal calcification than R-568 alone. This complexity demonstrates that treatment of one component of CKD-MBD may lead to undesirable effects on other components.

Operative Anatomy of the Human Skull: A Virtual Reality Expedition.

INTRODUCTION: The human cranial vault possesses an incredible, complex anatomical intricacy. Bridging the divide between 2-dimensional (2D) learning resources and the 3-dimensional (3D) world in which the anatomy becomes clinically relevant poses an intellectual challenge. Advances in computer graphics and modelling technologies have allowed increasingly accurate and representative resources to supplement cadaveric dissection specimens. OBJECTIVE: To create accurate virtual models of all cranial bones to augment education, research, and clinical endeavours. METHODS: Through a careful analysis of osteological specimens and high-resolution radiographic studies, a highly accurate virtual model of the human skull was created and annotated with relevant anatomical landmarks. RESULTS: The skull was divided into 6 major segments including frontal, ethmoid, sphenoid, temporal, parietal, and occipital bones. These bones were thoroughly annotated to demonstrate the intricate anatomical features. CONCLUSION: This virtual model has the potential to serve as a valuable resource for educational, research, and clinical endeavours, and demonstrates the significance of advances in computer modelling that can contribute to our understanding of neurosurgical anatomical substrates.

Using generalizability analysis to estimate parameters for anatomy assessments: A multi-institutional study.

With integrated curricula and multidisciplinary assessments becoming more prevalent in medical education, there is a continued need for educational research to explore the advantages, consequences, and challenges of integration practices. This retrospective analysis investigated the number of items needed to reliably assess anatomical knowledge in the context of gross anatomy and histology. A generalizability analysis was conducted on gross anatomy and histology written and practical examination items that were administered in a discipline-based format at Indiana University School of Medicine and in an integrated fashion at the University of Alabama School of Medicine and Rush University Medical College. Examination items were analyzed using a partially nested design s×(i:o) in which items were nested within occasions (i:o) and crossed with students (s). A reliability standard of 0.80 was used to determine the minimum number of items needed across examinations (occasions) to make reliable and informed decisions about students' competence in anatomical knowledge. Decision study plots are presented to demonstrate how the number of items per examination influences the reliability of each administered assessment. Using the example of a curriculum that assesses gross anatomy knowledge over five summative written and practical examinations, the results of the decision study estimated that 30 and 25 items would be needed on each written and practical examination to reach a reliability of 0.80, respectively. This study is particularly relevant to educators who may question whether the amount of anatomy content assessed in multidisciplinary evaluations is sufficient for making judgments about the anatomical aptitude of students. Anat Sci Educ 10: 109-119. © 2016 American Association of Anatomists.

Dietary ratio of n-6/n-3 PUFAs and docosahexaenoic acid: actions on bone mineral and serum biomarkers in ovariectomized rats.

Hypoestrogenic states escalate bone loss in animals and humans. This study evaluated the effects of the amount and ratio of dietary n-6 and n-3 polyunsaturated fatty acids (PUFAs) on bone mineral in 3-month-old sexually mature ovariectomized (OVX) Sprague-Dawley rats. For 12 weeks, the rats were fed either a high-PUFA (HP) or a low-PUFA (LP) diet with a ratio of n-6/n-3 PUFAs of 5:1 (HP5 and LP5) or 10:1 (HP10 and LP10). All diets (modified AIN-93G) provided 110.4 g/kg of fat from safflower oil and/or high-oleate safflower oil blended with n-3 PUFAs (DHASCO oil) as a source of docosahexaenoic acid (DHA). Fatty acid analyses confirmed that the dietary ratio of 5:1 significantly elevated the amount of DHA in the periosteum, marrow and cortical and trabecular bones of the femur. Dual-energy X-ray absorptiometry measurements for femur and tibia bone mineral content (BMC) and bone mineral density showed that the DHA-rich diets (HP5 and LP5) resulted in a significantly lower bone loss among the OVX rats at 12 weeks. Rats fed the LP diets displayed the lowest overall serum concentrations of the bone resorption biomarkers pyridinoline (Pyd) and deoxypyridinoline, whereas the bone formation marker osteocalcin was lowest in the HP groups. Regardless of the dietary PUFA content, DHA in the 5:1 diets (HP5 and LP5) preserved rat femur BMC in the absence of estrogen. This study indicates that the dietary ratio of n-6/n-3 PUFAs (LP5 and HP5) and bone tissue concentration of total long-chain n-3 PUFAs (DHA) minimize femur bone loss as evidenced by a higher BMC in OVX rats. These findings show that dietary DHA lowers the ratio of 18:2n-6 (linoleic acid)/n-3 in bone compartments and that this ratio in tissue correlates with reduced Pyd but higher bone alkaline phosphatase activity and BMC values that favor bone conservation in OVX rats.

Protective actions of soy isoflavones and n-3 PUFAs on bone mass in ovariectomized rats.

Ovariectomy (OVX) in female rats precipitates a marked reduction in endogenous estrogen concentrations and induces bone remodeling abnormalities that augment bone loss and increase the risk of developing osteopenia. This research examined the combined effects of two levels of soy isoflavones (IFs), trace (-IF) and high (+IF) (0.03 and 3.43 mg/g protein, respectively), and two levels of n-3 polyunsaturated fatty acids (PUFAs) on bone conservation in 2-month-old sexually mature OVX Sprague-Dawley rats. All dietary treatments provided 110.4 g/kg of fat from either safflower oil (N6) or a blend of safflower oil and menhaden oil (N3). OVX rats were randomly assigned to the N6-IF, N6+IF, N3-IF and N3+IF groups. The OVX and sham rats were euthanized after 12 weeks of feeding. Data for sequential femoral and tibial in vivo bone mineral density and bone mineral content (BMC) measurements were determined every 4 weeks. The hindlimb mineral data indicated a trend toward a positive bone mineral-sparing effect related to +IF. Among the OVX rats, those fed the N3+IF diet had a significantly higher value for tibial BMC. The concentration of serum pyridinoline cross-links was significantly lower in the N3+IF group. These findings indicate a complementary action of soy IFs and n-3 PUFAs for attenuating bone mineral reduction in OVX rats.

Investigating the use of quick response codes in the gross anatomy laboratory.

The use of quick response (QR) codes within undergraduate university courses is on the rise, yet literature concerning their use in medical education is scant. This study examined student perceptions on the usefulness of QR codes as learning aids in a medical gross anatomy course, statistically analyzed whether this learning aid impacted student performance, and evaluated whether performance could be explained by the frequency of QR code usage. Question prompts and QR codes tagged on cadaveric specimens and models were available for four weeks as learning aids to medical (n = 155) and doctor of physical therapy (n = 39) students. Each QR code provided answers to posed questions in the form of embedded text or hyperlinked web pages. Students' perceptions were gathered using a formative questionnaire and practical examination scores were used to assess potential gains in student achievement. Overall, students responded positively to the use of QR codes in the gross anatomy laboratory as 89% (57/64) agreed the codes augmented their learning of anatomy. The users' most noticeable objection to using QR codes was the reluctance to bring their smartphones into the gross anatomy laboratory. A comparison between the performance of QR code users and non-users was found to be nonsignificant (P = 0.113), and no significant gains in performance (P = 0.302) were observed after the intervention. Learners welcomed the implementation of QR code technology in the gross anatomy laboratory, yet this intervention had no apparent effect on practical examination performance.

A test of Ockham's razor: implications of conjugated linoleic acid in bone biology.

The philosopher William of Ockham is recognized for the maxim that an assumption introduced to explain a phenomenon must not be multiplied beyond necessity, or that the simplest explanation is probably the correct explanation. The general truth is that conjugated linoleic acids (CLAs) are nutrients. However, the demonstration that these isomers of octadecadienoic acid protect against cancers in rodents stimulated curiosity that directed significant resources to characterize the biological functions of these fatty acids in cell and animal models. The benefits to human subjects given supplements of CLA were at best modest. The disappointing results in humans should be taken as an opportunity to critically evaluate all findings of CLA use and to consolidate the common actions of this nutrient so that future investigations focus on specific isomers and the most reasonable mechanisms. As such, the principal and consistently reported benefits of CLA have been in improving cancer outcomes, reducing body fat in growing animals, and modulating cell functions. Recognizing where related actions of CLA converge in specific disease conditions and physiologic states is how research efforts should be directed to minimize the pursuit of superfluous theories. Here, we briefly review the current biological effects of CLA and attempt to integrate their potential effect on the physiology and health of the skeletal system. Thus, the purpose of this review is to advance the science of CLA and to identify areas of research in which these nutrients affect bone metabolism and skeletal health.

The pathophysiology of early-stage chronic kidney disease-mineral bone disorder (CKD-MBD) and response to phosphate binders in the rat.

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a systemic disorder that describes the complex bone and mineral abnormalities that occur in CKD. To understand the pathophysiology of CKD-MBD and determine whether the early use of phosphate binders would alter this physiology, we used a naturally occurring, slowly progressive model of CKD-MBD, the Cy/+ rat. Male Cy/+ rats were compared with their normal littermates at 20 weeks of age after 1 week of no phosphate binder, calcium carbonate, or sevelamer carbonate. The Cy/+ rat had renal function that was 50% of that of normal littermates, elevated parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23), decreased 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] levels, but normal calcium and phosphorus levels. There was a significant positive correlation of blood FGF23 and phosphorus levels and blood FGF23 and urine phosphorus levels. There was an inverse correlation between FGF23 and calcium levels. mRNA from the kidney demonstrated 50% reduction in klotho and Npt2a expression but no difference in CYP27B1. In the intestine, CKD animals had reduced active phosphate absorption in the jejunum using modified Ussing chambers and a reduction in Npt2b expression throughout the small intestine compared with normal littermates. In bone, mRNA expression of FGF23 was reduced (driven by lowering with phosphate binders), and TRAP expression was increased in CKD. By histology, there was increased osteoclast activity and number, and there were reductions in some measures of femoral neck mechanical strength. One week of phosphate binders reduced intestinal phosphate flux, serum phosphorus levels, and urinary phosphate excretion. These results demonstrate marked abnormalities in kidney, intestine, and bone in early CKD-MBD. While phosphate binders were effective in lowering urine phosphorus, they had little effect on end organs after 1 week of administration.

The endocannabinoid signaling system: a marriage of PUFA and musculoskeletal health.

The role of diet in health and diseases related to muscle and bone has been an area of active study. Recently, endocannabinoids (EC), endogenous derivatives of arachidonic acid, an omega-6 (n-6) polyunsaturated fatty acid (PUFA), have been discovered to play regulatory roles in bone mass and muscle energy metabolism. This signaling system consists of the G-protein coupled cannabinoid receptors, CB1 and CB2, expressed in central and peripheral tissues and cells, which are variably activated by the production and on demand release of endogenous and synthetic agonists and antagonists. We propose that the balance between omega-6 and omega-3 (n-3) PUFA is an important modifier for the activation and suppression of endocannabinoid receptors and therefore, downstream signaling actions in cells. The potential of dietary PUFA to regulate this signaling system to influence the metabolic and physiological outcomes favorable to musculoskeletal health is the purpose of this review. The important role of n-3 PUFA in metabolic and physiological processes that attenuate muscle and bone loss under conditions of disease and stress is one aspect described herein. In this review, we first introduce the EC agonists (ligands) and their receptors (CB1 and CB2) and the general actions of EC signaling in various organs and systems. Second, we describe EC signaling in bone and muscle and how dietary PUFA influence the levels of endogenous agonists. Third, we discuss the potential implications of how dietary PUFA impact this system to minimize muscle atrophy and osteopenia and support healthy muscle development and bone modeling.

Developmental and functional significance of the CSF-1 proteoglycan chondroitin sulfate chain.

The primary macrophage growth factor, colony-stimulating factor-1 (CSF-1), is homodimeric and exists in 3 biologically active isoforms: a membrane-spanning, cell-surface glycoprotein (csCSF-1) and secreted glycoprotein (sgCSF-1) and proteoglycan (spCSF-1) isoforms. To investigate the in vivo role of the chondroitin sulfate glycosaminoglycan (GAG) chain of spCSF-1, we created mice that exclusively express, in a normal tissue-specific and developmental manner, either the secreted precursor of spCSF-1 or the corresponding precursor in which the GAG addition site was mutated. The reproductive, hematopoietic tooth eruption and tissue macrophage defects of CSF-1-deficient, osteopetrotic Csf1(op)/Csf1(op) mice were corrected by transgenic expression of the precursors of either sgCSF-1 or spCSF-1. Furthermore, in contrast to the transgene encoding csCSF-1, both failed to completely correct growth retardation, suggesting a role for csCSF-1 in the regulation of body weight. However, spCSF-1, in contrast to sgCSF-1, completely resolved the osteopetrotic phenotype. Furthermore, in transgenic lines expressing different concentrations of sgCSF-1 or spCSF-1, spCSF-1 more efficiently corrected Csf1(op)/Csf1(op) defects of tooth eruption, eyelid opening, macrophage morphology, and B-cell deficiency than sgCSF-1. These results indicate an important role of the CSF-1 chondroitin sulfate proteoglycan in in vivo signaling by secreted CSF-1.