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Background. In COVID-19 patients, low serum vitamin D (VD) levels have been associated with severe acute respiratory failure and poor prognosis. In regular hemodialysis (HD) patients, there is VD deficiency and markedly reduced calcitriol levels, which may predispose them to worse outcomes of COVID-19 infection. Some hemodialysis patients receive treatment with drugs for secondary hyperparathyroidism, which have well known pleiotropic effects beyond mineral metabolism. The aim of this study was to evaluate the impact of VD status and the administration of active vitamin D medications, used to treat secondary hyperparathyroidism, on survival in a cohort of COVID-19 positive HD patients. Methods. A cross-sectional retrospective observational study was conducted from 12 March to 21 May 2020 in 288 HD patients with positive PCR for SARS-CoV2. Patients were from 52 different centers in Spain. Results. The percent of HD patients with COVID-19 was 6.1% (288 out of 4743). Mortality rate was 28.4% (81/285). Three patients were lost to follow-up. Serum 25(OH)D (calcidiol) level was 17.1 [10.6–27.5] ng/mL and was not significantly associated to mortality (OR 0.99 (0.97–1.01), p = 0.4). Patients receiving active vitamin D medications (16/94 (17%) vs. 65/191(34%), p = 0.003), including calcimimetics (4/49 (8.2%) vs. 77/236 (32.6%), p = 0.001), paricalcitol or calcimimetics (19/117 (16.2%) vs. 62/168 (36.9%), p &lt, 0.001), and also those on both paricalcitol and calcimimetics, to treat secondary hyperparathyroidism (SHPTH) (1/26 (3.8%) vs. 80/259 (30.9%), p &lt, 0.001) showed a lower mortality rate than patients receiving no treatment with either drug. Multivariate Cox regression analysis confirmed this increased survival. Conclusions. Our findings suggest that the use of paricalcitol, calcimimetics or the combination of both, seem to be associated with the improvement of survival in HD patients with COVID-19. No correlation was found between serum VD levels and prognosis or outcomes in HD patients with COVID-19. Prospective studies and clinical trials are needed to support these findings.

Background The high rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreading represents a challenge to haemodialysis (HD) units. While fast isolation of suspected cases plays an essential role to avoid disease outbreaks, significant rates of asymptomatic cases have recently been described. After detecting an outbreak in one of our HD clinics, wide SARS-CoV-2 screening and segregation of confirmed cases were performed. Methods The entire clinic population, 192 patients, underwent testing for SARS-CoV-2 detection by real-time reverse-transcriptase polymerase chain reaction . We used univariate and multivariate logistic regression to define variables involved in SARS-CoV-2 infection in our dialysis unit. Later, we analysed differences between symptomatic and asymptomatic SARS-CoV-2-positive patients. Results In total, 22 symptomatic and 14 of the 170 asymptomatic patients had a SARS-CoV-2-positive result. Living in a nursing home/homeless [odds ratio (OR) 3.54; P = 0.026], having been admitted to the reference hospital within the previous 2 weeks (OR 5.19; P = 0.002) and sharing health-care transportation with future symptomatic (OR 3.33; P = 0.013) and asymptomatic (OR 4.73; P = 0.002) positive patients were independent risk factors for a positive test. Nine positive patients (25.7%) remained asymptomatic after a 3-week follow-up. We found no significant differences between symptomatic and asymptomatic SARS-CoV-2-positive patients. Conclusions Detection of asymptomatic SARS-CoV-2-positive patients is probably one of the key points to controlling an outbreak in an HD unit. Sharing health-care transportation to the dialysis unit, living in a nursing home and having been admitted to the reference hospital within the previous 2 weeks, are major risk factors for SARS-CoV-2 infection.

Resumen Objetivo: Actualmente, existen pocos datos sobre la influencia a largo plazo del polimetilmetacrilato (PMMA) en la integridad de los cuerpos vertebrales tras la vertebroplastia percutánea (VP). Resulta de interés investigar la posible relación entre esta técnica y la aparición con el tiempo de fenómenos de osteólisis o la fragmentación del cemento en las vértebras intervenidas El objetivo de este trabajo fue investigar si, a largo plazo, existe una pérdida de efectividad y/o seguridad de la VP con PMMA. Material y métodos: Se analizaron radiografías de pacientes intervenidos correspondientes al post?operatorio inmediato y al estudio radiológico más reciente (VP hace más de 15 años). Con ambos estudios radiológicos, describimos: la altura del cuerpo vertebral, la angulación de platillos y la presencia de osteólisis alrededor del cemento en el tiempo. Resultados: Un total de 7 pacientes intervenidos mediante VP con PMMA hace 15 o más años accedieron a realizarse una nueva radiografía en nuestro Centro. Tras el análisis de sus imágenes post?operatorias (inmediatas y a 15 ó más años de la cirugía), no se observó en ninguna de las vértebras intervenidas pérdida de altura del cuerpo vertebral cementado, diferencias de angulación en los platillos, presencia de osteólisis alrededor del cemento o fragmentación del PMMA inyectado Conclusión: El PMMA inyectado en el cuerpo vertebral mantiene una situación estable en el tiempo (más de 15 años). No se observan cambios en la interfaz hueso-PMMA, osteólisis y/o cambios en la altura de los cuerpos vertebrales en los casos analizados. Summary Objetive: Currently, there are limited data on the long-term influence of polymethylmethacrylate (PMMA) on the integrity of vertebral bodies after percutaneous vertebroplasty (PVP). Interesting investigation is being carried out into the possible relationship between this technique and the appearance over time of osteolytic phenomena or cement fragmentation in the intervened vertebrae. The objective of our study was to investigate whether there is a loss of effectiveness and/or safety of PVP with PMMA in the long term. Material and method: X-rays were analyzed of intervened patients corresponding to the immediate post-operative and the most recent radiological study (PVP more than 15 years previous). With both radiological studies, we describe: the height of the vertebral body, the angulation of lamellar plates and osteolytic presence around the cement over time. Results: A total of 7 patients operated by PVP with PMMA 15 or more years earlier agreed to have a new radiograph in our center. After the analysis of their post-operative images (immediate and 15 or more years after surgery), no loss of height of the cemented vertebral body, differences in angulation in the lamellar plates, presence of osteolysis around the vertebrae was observed in any of the involved vertebrae cement or fragmentation of the injected PMMA. Conclusions: PMMA injected into the vertebral body remains stable over time (more than 15 years). There are no changes in the bone-PMMA interface, osteolysis and/or changes in the height of the vertebral bodies in the cases analyzed.

Evidence suggests that chiropractic manipulation might exert positive effects in osteoporotic patients. The aim of this study was to evaluate the effects of chiropractic manipulation on bone structure and skeletal muscle in rats with bone loss caused by ovariectomy (OVX). The 6-month old Sprague-Dawley rats at 10 weeks following OVX or sham operation (Sh) did not suffer chiropractic manipulation (NM group) or were submitted to true chiropractic manipulation using the chiropractic adjusting instrument Activator V® three times/week for 6 weeks as follows: Force 1 setting was applied onto the tibial tubercle of the rat right hind limb (TM group), whereas the corresponding left hind limb received a false manipulation (FM group) consisting of ActivatorV® firing in the air and slightly touching the tibial tubercle. Bone mineral density (BMD) and bone mineral content (BMC) were determined in long bones and L3–L4 vertebrae in all rats. Femora and tibia were analyzed by μCT. Mechano growth factor (MGF) was detected in long bones and soleus, quadriceps and tibial muscles by immunohistochemistry and Western blot. The decrease of BMD and BMC as well as trabecular bone impairment in the long bones of OVX rats vs Sh controls was partially reversed in the TM group versus FM or NM rats. This bone improvement by chiropractic manipulation was associated with an increased MGF expression in the quadriceps and the anterior tibial muscle in OVX rats. These findings support the notion that chiropractic manipulation can ameliorate osteoporotic bone at least partly by targeting skeletal muscle.

Affective disorders promote poorer outcomes in hemodialysis patients. According to the presence or not of depression/anxiety in these patients, aims were to analyze differences in sociodemographic, clinical and/or psychological factors and to identify predictors. One hundred eighty-six hemodialysis patients were classified based on their depression/anxiety status. Basal characteristics showed differences between groups where mainly male sex (Depression: OR 0.2, Anxiety: OR 0.3) albumin (Depression: OR 0.1, Anxiety: OR 0.2) and calcium levels (Depression: OR 0.5, Anxiety: OR 0.4), impaired quality of life (Depression: OR 1.4, Anxiety: OR 1.2) and psychological inflexibility (Depression: OR 1.3, Anxiety: OR 1.2) were associated (all p &lt, 0.01) to these mental conditions. Multivariate models showed that worse quality of life (OR 1.3, p &lt, 0.001) predicted depression while marital status (with a partner, OR 0.3, p = 0.025) and albumin levels (OR 0.1, p = 0.027) were protective factors. Depression represented a risk factor for anxiety (OR 1.2, p = 0.001), although calcium levels (OR 0.5, p = 0.039) would protect this state. Interestingly, psychological inflexibility predicted both disorders (Depression: OR 1.2, p &lt, 0.001 and Anxiety: OR 1.1, p = 0.002). Results highlight the relevance of well-trained multidisciplinary hemodialysis units to control the influence of these factors on the presence of depression/anxiety, and thus, their impact on the patients’ outcomes.

In the present study, the possibility that a diabetic (DM) status might worsen age-related bone deterioration was explored in mice. Male CD-1 mice aged 2 (young control group) or 16 months, nondiabetic or made diabetic by streptozotocin injections, were used. DM induced a decrease in bone volume, trabecular number, and eroded surface, and in mineral apposition and bone formation rates, but an increased trabecular separation, in L1-L3 vertebrae of aged mice. Three-point bending and reference point indentation tests showed slight changes pointing to increased frailty and brittleness in the mouse tibia of diabetic old mice. DM was related to a decreased expression of both vascular endothelial growth factor and its receptor 2, which paralleled that of femoral vasculature, and increased expression of the pro-adipogenic gene peroxisome proliferator-activated receptor γ and adipocyte number, without affecting β-catenin pathway in old mouse bone. Concomitant DM in old mice failed to affect total glutathione levels or activity of main anti-oxidative stress enzymes, although xanthine oxidase was slightly increased, in the bone marrow, but increased the senescence marker caveolin-1 gene. In conclusion, DM worsens bone alterations of aged mice, related to decreased bone turnover and bone vasculature and increased senescence, independently of the anti-oxidative stress machinery.

Work scholarship from the SEIOMM to attend the 35 Congress of the ASBMR (Baltimore, 2013). Summary Diabetes mellitus (DM) is a metabolic pathology characterised by chronic hyperglycemia due to a deficit in the production and/or action of insulin. DM, above all type I, is commonly associated with osteopenia/osteoporosis and with an increased risk of fractures. Insulin-like growth factor-I (IGF-I), a factor abundant in the bone matrix which plays a significant role in the development and maintenance of bone mass, diminishes with DM. Parathyroid hormone-related protein (PTHrP), a modulator of growth and osteoblast function, acts on osteoprogenitors, promoting osteoblast differentiation and bone regeneration. Its expression is reduced in the presence of DM. In this work we have evaluated and compared the osteogenic actions of PTHrP in mouse models with type 1 DM and IGF-I deficiency. Diabetic mice by injection of streptozotocin had a reduction in bone mass in the long bones associated with an increase in oxidised proteins and a reduction in the expression of genes related to the Wnt pathway and of β-catenin protein, as well as alterations in vertebral trabecular bone. In the mouse model with IGF-I deficit our results indicate the presence of osteopenia both in the femur (associated with an inhibition of the Wnt pathway) and the spine (L1-L5). Our findings demonstrate that the administration of PTHrP, predominantly through its N-terminal domain, modulates the canonical Wnt pathway in relation to its osteogenic actions in a diabetic situation and also, in part, in the absence of IGF-I.

Background Context Dramatic increases in the average life expectancy have led to increases in the variety of degenerative changes and deformities observed in the aging spine. The elderly population can present challenges for spine surgeons, not only because of increased comorbidities, but also because of the quality of their bones. Pedicle screws are the implants used most commonly in spinal surgery for fixation, but their efficacy depends directly on bone quality. Although polymethyl methacrylate (PMMA)-augmented screws represent an alternative for patients with osteoporotic vertebrae, their use has raised some concerns because of the possible association between cement leakages (CLs) and other morbidities. Purpose To analyze potential complications related to the use of cement-augmented screws for spinal fusion and to investigate the effectiveness of using these screws in the treatment of patients with low bone quality. Study Design A retrospective single-center study. Patient Sample This study included 313 consecutive patients who underwent spinal fusion using a total of 1,780 cement-augmented screws. Methods and Outcome Measures We analyzed potential complications related to the use of cement-augmented screws, including CL, vascular injury, infection, screw extraction problems, revision surgery, and instrument failure. There are no financial conflicts of interest to report. Results A total of 1,043 vertebrae were instrumented. Cement leakage was observed in 650 vertebrae (62.3%). There were no major clinical complications related to CL, but two patients (0.6%) had radicular pain related to CL at the S1 foramina. Of the 13 patients (4.1%) who developed deep infections requiring surgical debridement, two with chronic infections had possible spondylitis that required instrument removal. All patients responded well to antibiotic therapy. Revision surgery was performed in 56 patients (17.9%), most of whom had long construction. A total of 180 screws were removed as a result of revision. There were no problems with screw extraction. Conclusions These results demonstrate the efficacy and safety of cement-augmented screws for the treatment of patients with low bone mineral density.

Diabetes mellitus (DM) and aging are associated with bone fragility and increased fracture risk. Both (1-37) N- and (107-111) C-terminal parathyroid hormone-related protein (PTHrP) exhibit osteogenic properties. We here aimed to evaluate and compare the efficacy of either PTHrP (1-37) or PTHrP (107-111) loaded into gelatin-glutaraldehyde-coated hydroxyapatite (HA-Gel) foams to improve bone repair of a transcortical tibial defect in aging rats with or without DM, induced by streptozotocin injection at birth. Diabetic old rats showed bone structural deterioration compared to their age-matched controls. Histological and μ-computerized tomography studies showed incomplete bone repair at 4 weeks after implantation of unloaded Ha-Gel foams in the transcortical tibial defects, mainly in old rats with DM. However, enhanced defect healing, as shown by an increase of bone volume/tissue volume and trabecular and cortical thickness and decreased trabecular separation, occurred in the presence of either PTHrP peptide in the implants in old rats with or without DM. This was accompanied by newly formed bone tissue around the osteointegrated HA-Gel implant and increased gene expression of osteocalcin and vascular endothelial growth factor (bone formation and angiogenic markers, respectively), and decreased expression of Sost gene, a negative regulator of bone formation, in the healing bone area. Our findings suggest that local delivery of PTHrP (1-37) or PTHrP (107-111) from a degradable implant is an attractive strategy to improve bone regeneration in aged and diabetic subjects. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2060-2070, 2016.

Aim Haemophagocytic lymphohistiocytosis (HLH) is characterised by T cell and macrophage activation and excessive production of inflammatory cytokines. Genetic diagnosis is required to discriminate between primary forms (familial HLH, FHL), due to mutations in genes involved in cytolysis, and secondary forms. We aimed to analyse the genes coding for Munc13-4 (UNC13D) and syntaxin-11 (STX11) proteins in search of mutations that might explain HLH in 5 patients without perforin defects. Materials and methods Perforin expression was evaluated by flow cytometry, sCD25 was measured by ELISA and NK activity was investigated by the conventional functional assay. Coding regions and exons surroundings were sequenced for PRF1, UNC13D and STX11 genes. Results P1 and P2 developed severe early-onset HLH, P1 died at 6 months. P3, with a sister who died after HLH, responded well to treatment (HLH-2004), and had a second HLH episode two years later. P2 developed HLH at year 7 while in complete remission after lymphoblastic leukaemia. P4 and P5 were brothers who died at 5 and 6 years old due to an HLH and EBV mononucleosis infection. XLP was discarded because P4 was a girl. P1 and P3 showed mutations in UNC13D previously described as pathogenic. There were no changes in STX11. Conclusions UNC13D mutations were found in 50% of the HLH families without perforin defects and STX11 defects were not detected. These results agree with published series in which mutations in UNC13D explain up to 50% of FHL without PRF1 mutations, supporting a heterogeneous genetic background for this disease.

BACKGROUND AND PURPOSE Current data suggest that parathyroid hormone (PTH)-related peptide (PTHrP) domains other than the N-terminal PTH-like domain contribute to its role as an endogenous bone anabolic factor. PTHrP-107-139 inhibits bone resorption, a fact which has precluded an unequivocal demonstration of its possible anabolic action in vivo. We thus sought to characterize the osteogenic effects of this peptide using a mouse model of diabetic low-turnover osteopaenia. EXPERIMENTAL APPROACH PTHrP-107-139 was administered to streptozotocin-induced diabetic mice, with or without bone marrow ablation, for 13 days. Osteopaenia was confirmed by dual-energy X-ray absorptiometry and microcomputed tomography analysis. Histological analysis was performed on paraffin-embedded bone tissue sections by haematoxylin/eosin and Masson's staining, and tartrate-resistent acid phosphatase immunohistochemistry. Mouse bone marrow stromal cells and osteoblastic MC3T3-E1 cells were cultured in normal and/or high glucose (HG) medium. Osteogenic and adipogenic markers were assessed by real-time PCR, and PTHrP and the PTH1 receptor protein expression by Western blot analysis. KEY RESULTS PTHrP-107-139 reversed the alterations in bone structure and osteoblast function, and also promoted bone healing after marrow ablation without affecting the number of osteoclast-like cells in diabetic mice. This peptide also reversed the high-glucose-induced changes in osteogenic differentiation in both bone marrow stromal cells and the more differentiated MC3T3-E1 cells. CONCLUSIONS AND IMPLICATIONS These findings demonstrate that PTHrP-107-139 promotes bone formation in diabetic mice. This mouse model and in vitro cell cultures allowed us to identify various anabolic effects of this peptide in this scenario.

Glucagon-like peptide 1 (GLP-1) controls glucose metabolism in extrapancreatic tissues through receptors other than the pancreatic cAMP-linked GLP-1 receptor; also, GLP-1 induces an insulin- and PTH-independent bone anabolic action in insulin-resistant and type-2 diabetic rats. Here we searched for the presence and characteristics of GLP-1 receptors in osteoblastic MC3T3-E1 cells. [(125)I]-GLP-1 specific binding to MC3T3-E1 cells was time- and temperature-dependent, reaching maximal value at 30 min at 25 degrees C; in these conditions, [(125)I]-GLP-1 binding was dissociable, and displaced by GLP-1, partially by GLP-2, but not by exendin-4 (Ex-4), exendin-9 (Ex-9), glucagon or insulin; Scatchard analysis of the unlabeled GLP-1 data showed high and low affinity binding sites; cross-linking of GLP-1 binding revealed an estimated 70 kDa band, almost undetectable in the presence of 10(-6) M GLP-1. GLP-1, Ex-9, insulin or glucagon failed to modify cellular cAMP content, while GLP-2 and Ex-4 increased it. However, GLP-1 induced an immediate hydrolysis of glycosylphosphatidylinositols (GPIs) generating short-lived inositolphosphoglycans (IPGs), and an increase in phosphatidylinositol-3 kinase (PI3K) and mitogen activated protein kinase (MAPK) activities; Ex-4 also affected GPIs, but its action was delayed with respect to that of GLP-1. This incretin was found to decrease Runx2 but increased osteocalcin gene expression, without affecting that of osteoprotegerin or the canonical Wnt pathway activity in MC3T3-E1 cells which do not express the pancreatic GLP-1 receptor. Our data demonstrate for the first time that GLP-1 can directly and functionally interact with osteoblastic cells, possibly through a GPI/IPG-coupled receptor.

La diabetes mellitus (DM) es una patología metabólica caracterizada por hiperglucemia crónica debida al déficit de producción y/o acción de la insulina. La DM, sobre todo la tipo 1, se asocia comúnmente a osteopenia/osteoporosis y al aumento de riesgo de fracturas. El factor de crecimiento similar a la insulina tipo I (IGF-I), un factor abundante en la matriz ósea que ejerce un papel importante en el desarrollo y mantenimiento de la masa ósea, disminuye en la DM. La proteína relacionada con la parathormona (PTHrP), un modulador del crecimiento y la función osteoblástica, actúa sobre los osteoprogenitores promoviendo la diferenciación osteoblástica y la regeneración ósea. Su expresión disminuye en situación diabética. En este trabajo, hemos evaluado y comparado las acciones osteogénicas de la PTHrP en modelos murinos de DM tipo 1 y deficiente en IGF-I. Los ratones diabéticos por inyección de estreptozotocina presentan una disminución de la masa ósea en los huesos largos, asociada al incremento de proteínas oxidadas y a la disminución de expresión de genes relacionados con la vía Wnt y de la proteína β-catenina, además de mostrar alteraciones en el hueso trabecular vertebral. En el modelo de ratón con déficit de IGF-I, nuestros resultados indican una situación de osteopenia tanto en el fémur (asociado a una inhibición de la vía Wnt) como en la columna (L1-L5). Nuestros hallazgos demuestran que la administración de PTHrP, predominantemente a través de su dominio N-terminal, modula la vía de Wnt canónica en relación a sus acciones osteogénicas en situación diabética y, también en parte, en ausencia de IGF-I. Diabetes mellitus (DM) is a metabolic pathology characterised by chronic hyperglycemia due to a deficit in the production and/or action of insulin. DM, above all type I, is commonly associated with osteopenia/osteoporosis and with an increased risk of fractures. Insulin-like growth factor-I (IGF-I), a factor abundant in the bone matrix which plays a significant role in the development and maintenance of bone mass, diminishes with DM. Parathyroid hormone-related protein (PTHrP), a modulator of growth and osteoblast function, acts on osteoprogenitors, promoting osteoblast differentiation and bone regeneration. Its expression is reduced in the presence of DM. In this work we have evaluated and compared the osteogenic actions of PTHrP in mouse models with type 1 DM and IGF-I deficiency. Diabetic mice by injection of streptozotocin had a reduction in bone mass in the long bones associated with an increase in oxidised proteins and a reduction in the expression of genes related to the Wnt pathway and of β-catenin protein, as well as alterations in vertebral trabecular bone. In the mouse model with IGF-I deficit our results indicate the presence of osteopenia both in the femur (associated with an inhibition of the Wnt pathway) and the spine (L1-L5). Our findings demonstrate that the administration of PTHrP, predominantly through its N-terminal domain, modulates the canonical Wnt pathway in relation to its osteogenic actions in a diabetic situation and also, in part, in the absence of IGF-I.

PTHrP is an important regulator of bone remodelling, apparently by acting through several sequence domains. We here aimed to further delineate the functional roles of the nuclear localization signal (NLS) comprising the 88-107 amino acid sequence of PTHrP in osteoblasts. PTHrP mutants from a human PTHrP (-36/+139) cDNA (wild type) cloned into pcDNA3.1 plasmid with deletion (Δ) of the signal peptide (SP), NLS, T(107), or T107A replacing T(107) by A(107) were generated and stably transfected into osteoblastic MC3T3-E1 cells. In these cells, intracellular trafficking, cell proliferation and viability, as well as cell differentiation were evaluated. In these transfected cells, PTHrP was detected in the cytoplasm and also in the nucleus, except in the NLS mutant. Meanwhile, the PTH type 1 receptor (PTH1R) accumulates in the cytoplasm except for the ΔSP mutant in which the receptor remains at the cell membrane. PTHrP-wild type cells showed enhanced growth and viability, as well as an increased matrix mineralization, alkaline phosphatase activity, and osteocalcin gene expression; and these features were inhibited or abolished in ΔNLS or ΔT(107) mutants. Of note, these effects of PTHrP overexpression on cell growth and function were similarly decreased in the ΔSP mutant after PTH1R small interfering RNA transfection or by a PTH1R antagonist. The present in vitro findings suggest a mixed model for PTHrP actions on osteoblastic growth and function whereby this protein needs to be secreted and internalized via the PTH1R (autocrine/paracrine pathway) before NLS-dependent shuttling to the nucleus (intracrine pathway).

Biopolymer-coated nanocrystalline hydroxyapatite (HA) made as macroporous foams which are degradable and flexible are promising candidates as orthopaedic implants. The C-terminal (107-111) epitope of parathyroid hormone-related protein (PTHrP) exhibits osteogenic properties. The main aim of this study was to evaluate whether PTHrP (107-111) loading into gelatin-glutaraldehyde biopolymer-coated HA (HA(GIu)) scaffolds would produce an optimal biomaterial for tissue engineering applications. HA(GIu) scaffolds with and without PTHrP (107-111) were implanted into a cavitary defect performed in both distal tibial metaphysis of adult rats. Animals were sacrificed after 4 weeks for histological, microcomputerized tomography and gene expression analysis of the callus. At this time, bone healing occurred only in the presence of PTHrP (107-111)-containing HA(Giu) implant, related to an increase in bone volume/tissue volume and trabecular thickness, cortical thickness and gene expression of osteocalcin and vascular cell adhesion molecule I, but a decreased gene expression of Wnt inhibitors, SOST and dickkopf homolog 1. The autonomous osteogenic effect of the PTHrP (107-111)-loaded HA(Giu) scaffolds was confirmed in mouse and human osteoblastic cell cultures. Our findings demonstrate the advantage of loading PTHrP (107-111) into degradable HA(GIu) scaffolds for achieving an optimal biomaterial that is promising for low load bearing clinical applications. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Autophagy is a highly regulated homoeostatic process involved in the lysosomal degradation of damaged cell organelles and proteins. This process is considered an important pro-survival mechanism under diverse stress conditions. A diabetic milieu is known to hamper osteoblast viability and function. In the present study, we explored the putative protective role of autophagy in osteoblastic cells exposed to an HG (high glucose) medium. HG was found to increase protein oxidation and triggered autophagy by a mechanism dependent on reactive oxygen species overproduction in osteoblastic MC3T3-E1 cells. MC3T3-E1 cell survival was impaired by HG and worsened by chemical or genetic inhibition of autophagy. These findings were mimicked by H2O2-induced oxidative stress in these cells. Autophagy impairment led to both defective mitochondrial morphology and decreased bioenergetic machinery and inhibited further osteoblast differentiation in MC3T3-E1 cells upon exposure to HG. These novel findings indicate that autophagy is an essential mechanism to maintain osteoblast viability and function in an HG environment.

Insulin-like growth factor-I (IGF-I) deficiency causes growth delay, and IGF-I has been shown to partially mediate bone anabolism by parathyroid hormone (PTH). PTH-related protein (PTHrP) is abundant in bone, and has osteogenic features by poorly defined mechanisms. We here examined the capacity of PTHrP (1-36) and PTHrP (107-111) (osteostatin) to reverse the skeletal alterations associated with IGF-I deficiency. Igf1-null mice and their wild type littermates were treated with each PTHrP peptide (80 µg/Kg/every other day/2 weeks; 2 males and 4 females for each genotype) or saline vehicle (3 males and 3 females for each genotype). We found that treatment with either PTHrP peptide ameliorated trabecular structure in the femur in both genotypes. However, these peptides were ineffective in normalizing the altered cortical structure at this bone site in Igf1-null mice. An aberrant gene expression of factors associated with osteoblast differentiation and function, namely runx2, osteoprotegerin/receptor activator of NF-κB ligand ratio, Wnt3a , cyclin D1, connexin 43, catalase and Gadd45, as well as in osteocyte sclerostin, was found in the long bones of Igf1-null mice. These mice also displayed a lower amount of trabecular osteoblasts and osteoclasts in the tibial metaphysis than those in wild type mice. These alterations in Igf1-null mice were only partially corrected by each PTHrP peptide treatment. The skeletal expression of Igf2, Igf1 receptor and Irs2 was increased in Igf1-null mice, and this compensatory profile was further improved by treatment with each PTHrP peptide related to ERK1/2 and FoxM1 activation. In vitro, PTHrP (1-36) and osteostatin were effective in promoting bone marrow stromal cell mineralization in normal mice but not in IGF-I-deficient mice. Collectively, these findings indicate that PTHrP (1-36) and osteostatin can exert several osteogenic actions even in the absence of IGF-I in the mouse bone.

Recent in vivo findings suggest that the bone sparing effect of parathyroid hormone-related protein (PTHrP) in diabetic mice might occur at least in part through targeting a suppressed Wnt/β-catenin pathway in osteoblasts. We here aimed to examine the inhibitory action of a high glucose environment on specific components of the canonical Wnt pathway, and the putative compensatory effects of PTHrP, in osteoblastic cell cultures. Mouse osteoblastic MC3T3-E1 cells and primary cultures of fetal mouse calvaria were exposed to normal (5.5 mM) or high (25 mM) D-glucose (HG), with or without PTHrP (1-36) or PTHrP (107-139) for different times. In some experiments, MC3T3-E1 cells were incubated with the Wnt pathway activators Wnt3a and LiCl, or were transfected with plasmids encoding either a mutated β-catenin that cannot be targeted for degradation or a human PTHrP (-36/+139) cDNA, or the corresponding empty plasmid, in the presence or absence of HG. The gene expression of Wnt3a and low density receptor-like proteins (LRP)-5 and 6, as well as β-catenin protein stabilization and β-catenin-dependent transcription activity were evaluated. Oxidative stress status under HG condition was also assessed. The present data demonstrate that HG can target different components of the canonical Wnt pathway, while β-catenin degradation appears to be a key event leading to inhibition of Wnt/β-catenin signaling in mouse osteoblastic cells. Both PTHrP peptides tested were able to counteract this deleterious action of HG. These in vitro findings also provide new clues to understand the underlying mechanisms whereby PTHrP can increase bone formation.

Cuando se habla de redes de neuronas, se debe saber que son un sistema de computación que utilizando en una serie de muestras o ejemplos es capaz de aprender para posteriormente, basándose en ese aprendizaje, estar preparado para reaccionar de forma óptima ante otros estímulos. Existe gran variedad de redes de neuronas, en este caso, nos vamos a centrar en las redes de neuronas de base radial (RNBR), las cuales utilizan funciones de activación de base radial como lo es la función normal (gaussiana). Habitualmente se utilizan distancias euclídeas, que son simétricas en todas las dimensiones del espacio de entrada y por lo tanto no existe ponderación alguna que dé más importancia a unas entradas sobre otras. Ingeniería Técnica en Informática de Gestión