Spectral dynamic causal modelling in healthy women reveals brain connectivity changes along the menstrual cycle

Longitudinal menstrual cycle studies allow to investigate the effects of ovarian hormones on brain organization. Here, we use spectral dynamic causal modelling (spDCM) in a triple network model to assess effective connectivity changes along the menstrual cycle within and between the default mode, salience and executive control networks (DMN, SN, and ECN). Sixty healthy young women were scanned three times along their menstrual cycle, during early follicular, pre-ovulatory and mid-luteal phase. Related to estradiol, right before ovulation the left insula recruits the ECN, while the right middle frontal gyrus decreases its connectivity to the precuneus and the DMN decouples into anterior/posterior parts. Related to progesterone during the mid-luteal phase, the insulae (SN) engage to each other, while decreasing their connectivity to parietal ECN, which in turn engages the posterior DMN. When including the most confident connections in a leave-one out cross-validation, we find an above-chance prediction of the left-out subjects’ cycle phase. These findings corroborate the plasticity of the female brain in response to acute hormone fluctuations and may help to further understand the neuroendocrine interactions underlying cognitive changes along the menstrual cycle

Regional diversity in the murine cortical vascular network is revealed by synchrotron X-ray tomography and is amplified with age

Cortical bone is permeated by a system of pores, occupied by the blood supply and osteocytes. With ageing, bone mass reduction and disruption of the microstructure are associated with reduced vascular supply. Insight into the regulation of the blood supply to the bone could enhance the understanding of bone strength determinants and fracture healing. Using synchrotron radiation-based computed tomography, the distribution of vascular canals and osteocyte lacunae was assessed in murine cortical bone and the influence of age on these parameters was investigated. The tibiofibular junction from 15-week- and 10-month-old female C57BL/6J mice were imaged post-mortem. Vascular canals and three-dimensional spatial relationships between osteocyte lacunae and bone surfaces were computed for both age groups. At 15 weeks, the posterior region of the tibiofibular junction had a higher vascular canal volume density than the anterior, lateral and medial regions. Intracortical vascular networks in anterior and posterior regions were also different, with connectedness in the posterior higher than the anterior at 15 weeks. By 10 months, cortices were thinner, with cortical area fraction and vascular density reduced, but only in the posterior cortex. This provided the first evidence of age-related effects on murine bone porosity due to the location of the intracortical vasculature. Targeting the vasculature to modulate bone porosity could provide an effective way to treat degenerative bone diseases, such as osteoporosis

Occurence of Solanum elaeagnifolium Cav. in Mysore city, Karnataka

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A DCM for resting state fMRI

This technical note introduces a dynamic causal model (DCM) for resting state fMRI time series based upon observed functional connectivity-as measured by the cross spectra among different brain regions. This DCM is based upon a deterministic model that generates predicted crossed spectra from a biophysically plausible model of coupled neuronal fluctuations in a distributed neuronal network or graph. Effectively, the resulting scheme finds the best effective connectivity among hidden neuronal states that explains the observed functional connectivity among haemodynamic responses. This is because the cross spectra contain all the information about (second order) statistical dependencies among regional dynamics. In this note, we focus on describing the model, its relationship to existing measures of directed and undirected functional connectivity and establishing its face validity using simulations. In subsequent papers, we will evaluate its construct validity in relation to stochastic DCM and its predictive validity in Parkinson's and Huntington's disease

Lasting organ-level bone mechanoadaptation is unrelated to local strain

Bones adapt to mechanical forces according to strict principles predicting straight shape. Most bones are, however, paradoxically curved. To solve this paradox, we used computed tomography–based, four-dimensional imaging methods and computational analysis to monitor acute and chronic whole-bone shape adaptation and remodeling in vivo. We first confirmed that some acute load-induced structural changes are reversible, adhere to the linear strain magnitude regulation of remodeling activities, and are restricted to bone regions in which marked antiresorptive actions are evident. We make the novel observation that loading exerts significant lasting modifications in tibial shape and mass across extensive bone regions, underpinned by (re)modeling independent of local strain magnitude, occurring at sites where the initial response to load is principally osteogenic. This is the first report to demonstrate that bone loading stimulates nonlinear remodeling responses to strain that culminate in greater curvature adjusted for load predictability without sacrificing strength

A suggested prototype for assessing bone health

Background- Osteoporosis is becoming a health concern worldwide. Considering the fact that prevention plays an important role in reducing the burden of this silent disease and in view of the limited resources available, many countries have adopted certain programs to fight osteoporosis through shifting their attention towards at-risk individuals. The Iranian Multicenter Osteoporosis Study (IMOS) is one of these programs. The program aims to assess bone health and the prevalence of vitamin D deficiency in different parts of Iran with various altitudes, latitudes and lifestyle habits in a way that the results could be generalized to the country. Method- The present article presents the protocol used in the third phase of the study. It was designed based on the experiences gathered in the previous phases to overcome the shortcomings particularly subject loss. The questionnaire applied in this study was developed based on a thorough literature review of the risk factors and secondary causes of osteoporosis and was approved by an expert panel. It should be added that while the majority of the existing studies aim to study a certain aspect of osteoporosis, the present protocol provides the information needed for policy makers and researchers to study different osteoporosis-related issues. Conclusion- The authors believe the protocol, to be implemented with small modifications, can help policymakers in different parts of the world, particularly developing countries, gather accurate information on different aspects of bone health at the national level. © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved

A summary of new predictive high frequency thermo-vibrational models in porous media

In this chapter, we consider the effect of mechanical vibration on the onset of convection in porous media. The porous media is saturated either by a pure fluid or by a binary mixture. The importance of transport model on stability diagrams are presented and discussed. The stability threshold for the Darcy-Brinkman case in the RaTc-R and kc-R diagrams are presented (where RaTc, kc and R are the critical Rayleigh number, the critical wave number and the vibration parameters respectively). It is shown that there is a significant deviation from the Darcy model. In the thermo-solutal case with the Soret effect, the influence of vibration on the reduction of multi-cellular convection is emphasized. A new analytical relation for obtaining the threshold of mono-cellular convection is derived. This relation shows how the separation factor Ψ is related to controlling parameters of the problem, Ψ = f (R, ε*, Le) when the wave number k -> 0. The importance of vibrational parameter definition is highlighted and it is shown how, by using a proper definition for vibrational parameter, we may obtain compact relationship. It is also shown how this result may be used to increase components separation

Vitamin D receptor gene polymorphisms and susceptibility to urolithiasis: a meta-regression and meta-analysis

Background: The currently available data with respect to the association between vitamin D receptor (VDR) gene polymorphism and risk to urolithiasis are inconclusive and inconsistent. Hence, an exhaustive meta-analysis can solve the discrepancies and provide a hint for upcoming investigations. Herein, a meta-analysis was carried out to attain a conclusive estimate of the association between VDR gene single nucleotide polymorphisms (SNPs) and urolithiasis risk. Methods: The major databases, including ISI Web of science, Scopus, and PubMed/MEDLINE were searched systematically from until June 2020 to retrieve all relevant studies. Association between VDR gene polymorphisms, including FokI (rs2228570), TaqI (rs731236), BsmI (rs1544410), and ApaI (rs7975232), and urolithiasis risk was evaluated using pooled odds ratio (OR) and their corresponding 95 confidence interval (CI). Additionally, to seek for the potential source of heterogeneity, meta-regression analyses were exerted. Results: Literature search led to finally finding of 33 studies evaluating the VDR gene SNPs and urolithiasis risk. It was observed that none of the four SNPs were significantly associated with urolithiasis predisposition. However, subgroup analysis confirmed higher risk of urolithiasis in East-Asian and Caucasian population with ApaI and TaqI gene polymorphism. The analyses of sensitivity acknowledged the results stability. Conclusion: Although this meta-analysis did not support the association of FokI, TaqI, BsmI, and ApaI in the overall polled analysis, it suggests that ApaI and TaqI SNPs is associated with increased risk of urolithiasis in East-Asian and Caucasians populations. © 2020 The Author(s)

Transient peak-strain matching partially recovers the age-impaired mechanoadaptive cortical bone response

Mechanoadaptation maintains bone mass and architecture; its failure underlies age-related decline in bone strength. It is unclear whether this is due to failure of osteocytes to sense strain, osteoblasts to form bone or insufficient mechanical stimulus. Mechanoadaptation can be restored to aged bone by surgical neurectomy, suggesting that changes in loading history can rescue mechanoadaptation. We use non-biased, whole-bone tibial analyses, along with characterisation of surface strains and ensuing mechanoadaptive responses in mice at a range of ages, to explore whether sufficient load magnitude can activate mechanoadaptation in aged bone. We find that younger mice adapt when imposed strains are lower than in mature and aged bone. Intriguingly, imposition of short-term, high magnitude loading effectively primes cortical but not trabecular bone of aged mice to respond. This response was regionally-matched to highest strains measured by digital image correlation and to osteocytic mechanoactivation. These data indicate that aged bone’s loading response can be partially recovered, non-invasively by transient, focal high strain regions. Our results indicate that old murine bone does respond to load when the loading is of sufficient magnitude, and bones’ age-related adaptation failure may be due to insufficient mechanical stimulus to trigger mechanoadaptation

Associations between the lipid profile and the lumbar spine bone mineral density and trabecular bone score in elderly Iranian individuals participating in the Bushehr Elderly Health Program: a population-based study

Summary: We hypothesized that the lipid profile or dyslipidemia may have an influence on the bone mineral density and bone microstructure in an elderly Iranian population. The results of this study showed some significant associations between the serum lipid levels and the lumbar spine and femoral areal bone mineral densities and the trabecular bone score (TBS). Purpose: Serum lipid abnormalities are possible risk factors for cardiovascular diseases and osteoporosis. Our aim was to evaluate the associations between the lipid profile and the areal bone mineral density (aBMD) and trabecular bone score in an elderly Iranian population. Methods: The study subjects included 2426 elderly women and men participating in the second stage of the Bushehr Elderly Health program, a population-based prospective cohort study. The aBMDs of the lumbar spine and femoral neck and the lumbar spine texture were measured using dual-energy X-ray absorptiometry and the TBS algorithm, respectively. The associations between the lipid profiles and the aBMDs and TBSs were examined using multivariable linear regression analyses stratified by sex and adjusted for potential confounders. Results: In men, we found negative correlations between the lumbar spine aBMD and TBS and the total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) levels (TC: p < 0.001 and p < 0.006, HDL-C: p = 0.002 and p = 0.004, and LDL-C: p < 0.001 and p < 0.009, respectively). However, only the HDL-C level was negatively associated with the aBMD in women (p = 0.016). A positive and statistically significant correlation was found between the serum triglyceride (TG) level and the aBMD in the women (p < 0.001). The TG level and the TBS were not statistically significantly correlated in either sex, and the TBS was not correlated with any of the lipid values in women. Conclusion: The results of this study showed some significant but generally weak associations between the lipid profile and the aBMD. The associations that were significant for both the men and the women included positive associations between the TG level and the femoral neck aBMD, as well as the HDL-C level and the femoral neck and lumbar spine aBMD