La diabetes altera el potencial osteogénico de células progenitoras de médula ósea: efectos del tratamiento con metformina

En este trabajo, estudiamos el efecto de una Diabetes inducida por destrucción parcial de la masa de células beta pancreáticas, sobre el compromiso osteogénico de células progenitoras de médula ósea (CPMO), y su modulación por el tratamiento oral con Metformina. Para ello utilizamos ratas Sprague Dawley, divididas en cuatro grupos: controles [C], controles tratadas con Metformina [M], diabéticas [D], y diabéticas tratadas con Metformina [DM]. La inducción de Diabetes se realizó, por inyección intraperitoneal sucesiva de ácido nicotínico y estreptozotocina. Sobre los cultivos de CPMO se evaluó la actividad específica de Fosfatasa Alcalina (FAL) y la producción de Colágeno tipo 1 (Col-1) en estado basal y en medio de diferenciación osteogénico luego de 15 días. A los 21 días, se evaluaron los depósitos de mineral extracelular. La FAL y el Col-1 de CPMO basales, no mostraron diferencias significativas entre los cuatro grupos experimentales. Al cabo de 15 días, las CPMO de ratas M mostraron un incremento en el Col-1 de 122 % respecto de C; D 30 % respecto de C y DM 68 % respecto de C. La FAL expresó un 171 % para M, 34 % para D; y 125 % para DM todos respecto de C. Luego de 21 días, se observó una disminución en la mineralización de las CPMO de D (65 % respecto del grupo C). El tratamiento con metformina incrementó la mineralización de las CPMO en todos los casos. En conclusión, en nuestro modelo experimental de Diabetes, ésta disminuye el potencial osteogénico de las CPMO, un efecto que es parcialmente revertido por el tratamiento oral con Metformina. Estos hallazgos podrían explicar, al menos en parte, las alteraciones óseas descriptas en el hueso asociadas con la Diabetes.Diabetes mellitus is associated with an increased incidence of skeletal abnormalities, resulting in lower bone formation and/or remodeling. Osteopenia, osteoporosis and an increased incidence of non-traumatic fractures has been particularly observed in patients with type 2 diabetes. Recently, we have demonstrated that metformin has in vitro and in vivo osteogenic effects: (a) it stimulates the proliferation, differentiation and mineralization of osteoblasts in culture, and (b) in non-diabetic rats, it increases the repair of minimal bone lesions and improves femoral trabecular bone microarchitecture. In this study, we evaluated in rats the effect of diabetes induction by a partial destruction of pancreatic beta cells, on the osteogenic commitment of bone marrow progenitor cells (BMPC), and the modulation of this effect by orally administered metformin. We used young male Sprague Dawley rats (200 g), divided into four groups: untreated non-diabetic controls [C], non-diabetic rats treated for 2 weeks with metformin administered in drinking water (100 mg/kg/day) [M], untreated diabetic rats [D], and diabetic rats treated for 2 weeks with metformin (100 mg/kg/day) [DM]. Induction of Diabetes was performed one week prior to treatment with metformin, by successive intraperitoneal injections with 75 mg/kg body weight of nicotinic acid and 60 mg/kg body weight of streptozotocin. At the end of all treatments, blood samples were obtained to confirm the development of Diabetes, after which the animals were sacrificed by cervical dislocation under anesthesia. Femora and/or tibiae were dissected, and bone marrow cells were collected by flushing the bone diaphysal canal with Dulbecco’s modified essential medium (DMEM) under sterile conditions. Adherent cells were grown to confluence in DMEM-10 % fetal bovine serum (FBS), after which we assessed alkaline phosphatase specific activity (ALP) by an enzymatic kinetic method, and type 1 collagen production (Col-1) by a Sirius Red colorimetric method (basal osteoblastic differentiation of BMPC). Subsequently, BMPC were submitted to an osteogenic induction for 15 days with an osteogenic medium (DMEM-10 % FBS containing ascorbic acid and sodium beta-glycerophosphate), after which ALP and Col-1 were evaluated. Basal ALP activity and type 1 collagen production (BMPC without osteogenic differentiation) showed no significant differences between the four experimental groups. After 15 days of culture in osteogenic medium, BMPC from control rats increased their expression of ALP (5 times compared to baseline) and collagen production (11 times compared to baseline). BMPC from diabetic rats after 15 days culture in osteogenic medium, also showed a significant (although smaller) increase in ALP (2-3 fold over basal activity) and collagen production (4-fold compared to baseline). BMPC obtained from rats treated with metformin (groups M and DM) and submitted to osteogenic induction for 15 days, showed an approximately 2-4-fold increase in both ALP and Col-1 (when compared with groups C and D, respectively). After 21 days of osteogenic induction, a decrease was observed in the mineralization of BMPC obtained from group D (65 % of that for group C). Treatment with metformin increased the mineralizing capacity of BMPC in all cases, including a reversal of the inhibitory effect of Diabetes on this parameter. In conclusion, we have found that our model of Diabetes reduces the osteogenic potential of bone marrow progenitor cells, and that this effect is partially reverted by orally administered metformin. These findings could explain, at least in part, the bone alterations that have been associated with Diabetes mellitus

Local spatial structure of forest biomass and its consequences for remote sensing of carbon stocks

Advances in forest carbon mapping have the potential to greatly reduce uncertainties in the global carbon budget and to facilitate effective emissions mitigation strategies such as REDD+. Though broad scale mapping is based primarily on remote sensing data, the accuracy of resulting forest carbon stock estimates depends critically on the quality of field measurements and calibration procedures. The mismatch in spatial scales between field inventory plots and larger pixels of current and planned remote sensing products for forest biomass mapping is of particular concern, as it has the potential to introduce errors, especially if forest biomass shows strong local spatial variation. Here, we used 30 large (8–50 ha) globally distributed permanent forest plots to quantify the spatial variability in aboveground biomass (AGB) at spatial grains ranging from 5 to 250m (0.025–6.25 ha), and we evaluate the implications of this variability for calibrating remote sensing products using simulated remote sensing footprints. We found that the spatial sampling error in AGB is large for standard plot sizes, averaging 46.3% for 0.1 ha subplots and 16.6% for 1 ha subplots. Topographically heterogeneous sites showed positive spatial autocorrelation in AGB at scales of 100m and above; at smaller scales, most study sites showed negative or nonexistent spatial autocorrelation in AGB. We further show that when field calibration plots are smaller than the remote sensing pixels, the high local spatial variability in AGB leads to a substantial “dilution” bias in calibration parameters, a bias that cannot be removed with current statistical methods. Overall, our results suggest that topography should be explicitly accounted for in future sampling strategies and that much care must be taken in designing calibration schemes if remote sensing of forest carbon is to achieve its promise

Development of a validated patient-reported symptom metric for pediatric Eosinophilic Esophagitis: qualitative methods

<p>Abstract</p> <p>Background</p> <p>Previous attempts to measure symptoms in pediatric Eosinophilic Esophagitis (EoE) have not fully included patients and parents in the item development process. We sought to identify and validate key patient self-reported and parent proxy-reported outcomes (PROs) specific to EoE.</p> <p>Methods</p> <p>We developed methodology for focus and cognitive interviews based on the Food and Drug Administration (FDA) guidelines for PROs, the validated generic PedsQL™ guidelines, and the consolidated criteria for reporting qualitative research (COREQ). Both child (ages 8-12 and 13-18) and parent-proxy (ages 2-4, 5-7, 8-12, and 13-18) interviews were conducted.</p> <p>Results</p> <p>We conducted 75 interviews to construct the new instrument. Items were identified and developed from individual focus interviews, followed by cognitive interviews for face and content validation. Initial domains of symptom frequency and severity were developed, and open-ended questions were used to generate specific items during the focus interviews. Once developed, the instrument construct, instructions, timeframe, scoring, and specific items were systematically reviewed with a separate group of patients and their parents during the cognitive interviews.</p> <p>Conclusions</p> <p>To capture the full impact of pediatric EoE, both histologic findings and PROs need to be included as equally important outcome measures. We have developed the face and content validated Pediatric Eosinophilic Esophagitis Symptom Score (PEESS™ v2.0). The PEESS™ v2.0 metric is now undergoing multisite national field testing as the next iterative instrument development phase.</p

Natural disturbance impacts on trade-offs and co-benefits of forest biodiversity and carbon

With accelerating environmental change, understanding forest disturbance impacts on trade-offs between biodiversity and carbon dynamics is of high socio-economic importance. Most studies, however, have assessed immediate or short-term effects of disturbance, while long-term impacts remain poorly understood. Using a tree-ring-based approach, we analysed the effect of 250 years of disturbances on present-day biodiversity indicators and carbon dynamics in primary forests. Disturbance legacies spanning centuries shaped contemporary forest co-benefits and trade-offs, with contrasting, local-scale effects. Disturbances enhanced carbon sequestration, reaching maximum rates within a comparatively narrow post-disturbance window (up to 50 years). Concurrently, disturbance diminished aboveground carbon storage, which gradually returned to peak levels over centuries. Temporal patterns in biodiversity potential were bimodal; the first maximum coincided with the short-term post-disturbance carbon sequestration peak, and the second occurred during periods of maximum carbon storage in complex old-growth forest. Despite fluctuating local-scale trade-offs, forest biodiversity and carbon storage remained stable across the broader study region, and our data support a positive relationship between carbon stocks and biodiversity potential. These findings underscore the interdependencies of forest processes, and highlight the necessity of large-scale conservation programmes to effectively promote both biodiversity and long-term carbon storage, particularly given the accelerating global biodiversity and climate crises

Reliability, validity and psychometric properties of the Greek translation of the Major Depression Inventory

BACKGROUND: The Major Depression Inventory (MDI) is a brief self-rating scale for the assessment of depression. It is reported to be valid because it is based on the universe of symptoms of DSM-IV and ICD-10 depression. The aim of the current preliminary study was to assess the reliability, validity and psychometric properties of the Greek translation of the MDI. METHODS: 30 depressed patients of mean age 23.41 (± 5.77) years, and 68 controls patients of mean age 25.08 (± 11.42) years, entered the study. In 18 of them, the instrument was re-applied 1–2 days later and the Translation and Back Translation made. Clinical diagnosis was reached with the use of the SCAN v.2.0 and the International Personality Disorders Examination (IPDE). The Center for Epidemiological Studies-Depression (CES-D) and the Zung Depression Rating Scale (ZDRS) were applied for cross-validation purposes. Statistical analysis included ANOVA, the Spearman Product Moment Correlation Coefficient, Principal Components Analysis and the calculation of Cronbach's α. RESULTS: Sensitivity and specificity were 0.86 and 0.94, respectively, at 26/27. Cronbach's α for the total scale was equal to 0.89. The Spearman's rho between MDI and CES-D was 0.86 and between MDI and ZDRS was 0.76. The factor analysis revealed two factors but the first accounted for 54% of variance while the second only for 9%. The test-retest reliability was excellent (Spearman's rho between 0.53 and 0.96 for individual items and 0.89 for total score). CONCLUSION: The current study provided preliminary evidence concerning the reliability and validity of the Greek translation of the MDI. Its properties are similar to those reported in the international literature, but further research is necessary

The interplay of agency, culture and networks in field evolution

We examine organizational field change instigated by activists. Contrary to existing views emphasizing incumbent resistance, we suggest that collaboration between incumbents and challenger movements may emerge when a movement's cultural and relational fabric becomes moderately structured, creating threats and market opportunities but remaining permeable to external influence. We also elucidate how lead incumbents' attempts at movement cooptation may be deflected through distributed brokerage. The resulting confluence of cultural and relational "structuration" between movement and field accelerates the pace but dilutes the radicalness of institutional innovation, ensuring ongoing, incremental field change. Overall, this article contributes to the emergent literature on field dynamics by uncovering the evolution and outcomes of collaborative work at the intersection of social movements and incumbent fields

A Genome-Scale DNA Repair RNAi Screen Identifies SPG48 as a Novel Gene Associated with Hereditary Spastic Paraplegia

We have identified a novel gene in a genome-wide, double-strand break DNA repair RNAi screen and show that is involved in the neurological disease hereditary spastic paraplegia

Outcome reporting in randomised controlled trials and meta-analyses of appendicitis treatments in children: a systematic review

Background: Acute appendicitis is the most common surgical emergency in children. Despite this, there is no core outcome set (COS) described for randomised controlled trials (RCTs) in children with appendicitis and hence no consensus regarding outcome selection, definition and reporting. We aimed to identify outcomes currently reported in studies of paediatric appendicitis. / Methods: Using a defined, sensitive search strategy, we identified RCTs and systematic reviews (SRs) of treatment interventions in children with appendicitis. Included studies were all in English and investigated the effect of one or more treatment interventions in children with acute appendicitis or undergoing appendicectomy for presumed acute appendicitis. Studies were reviewed and data extracted by two reviewers. Primary (if defined) and all other outcomes were recorded and assigned to the core areas ‘Death’, ‘Pathophysiological Manifestations’, ‘Life Impact’, ‘Resource Use’ and ‘Adverse Events’, using OMERACT Filter 2.0. / Results: A total of 63 studies met the inclusion criteria reporting outcomes from 51 RCTs and nine SRs. Only 25 RCTs and four SRs defined a primary outcome. A total of 115 unique and different outcomes were identified. RCTs reported a median of nine outcomes each (range 1 to 14). The most frequently reported outcomes were wound infection (43 RCTs, nine SRs), intra-peritoneal abscess (41 RCTs, seven SRs) and length of stay (35 RCTs, six SRs) yet all three were reported in just 25 RCTs and five SRs. Common outcomes had multiple different definitions or were frequently not defined. Although outcomes were reported within all core areas, just one RCT and no SR reported outcomes for all core areas. Outcomes assigned to the ‘Death’ and ‘Life Impact’ core areas were reported least frequently (in six and 15 RCTs respectively). / Conclusions: There is a wide heterogeneity in the selection and definition of outcomes in paediatric appendicitis, and little overlap in outcomes used across studies. A paucity of studies report patient relevant outcomes within the ‘Life Impact’ core area. These factors preclude meaningful evidence synthesis, and pose challenges to designing prospective clinical trials and cohort studies. The development of a COS for paediatric appendicitis is warranted

Locally Administrated Perindopril Improves Healing in an Ovariectomized Rat Tibial Osteotomy Model

Angiotensin-converting enzyme inhibitors are widely prescribed to regulate blood pressure. High doses of orally administered perindopril have previously been shown to improve fracture healing in a mouse femur fracture model. In this study, perindopril was administered directly to the fracture area with the goal of stimulating fracture repair. Three months after being ovariectomized (OVX), tibial fractures were produced in Sprague–Dawley rats and subsequently stabilized with intramedullary wires. Perindopril (0.4 mg/kg/day) was injected locally at the fractured site for a treatment period of 7 days. Vehicle reagent was used as a control. Callus quality was evaluated at 2 and 4 weeks post-fracture. Compared with the vehicle group, perindopril treatment significantly increased bone formation, increased biomechanical strength, and improved microstructural parameters of the callus. Newly woven bone was arranged more tightly and regularly at 4 weeks post-fracture. The ultimate load increased by 66.1 and 76.9% (p<0.01), and the bone volume over total volume (BV/TV) increased by 29.9% and 24.3% (p<0.01) at 2 and 4 weeks post-fracture, respectively. These findings suggest that local treatment with perindopril could promote fracture healing in ovariectomized rats