Small amounts of water can significantly affect the physical properties of mantle materials, including lowering of the solidus, and reducing effective viscosity and seismic velocity. The amount and ...distribution of water within the mantle thus has profound implications for the dynamics and geochemical evolution of the Earth. Electrical conductivity is also highly sensitive to the presence of hydrogen in mantle minerals. The mantle transition zone minerals wadsleyite and ringwoodite in particular have high water solubility, and recent high pressure experiments show that the electrical conductivity of these minerals is very sensitive to water content. Thus estimates of the electrical conductivity of the mantle transition zone derived from electromagnetic induction studies have the potential to constrain the water content of this region. Here we invert long period geomagnetic response functions to derive a global-scale three-dimensional model of electrical conductivity variations in the Earth's mantle, revealing variations in the electrical conductivity of the transition zone of approximately one order of magnitude. Conductivities are high in cold, seismically fast, areas where slabs have subducted into or through the transition zone. Significant variations in water content throughout the transition zone provide a plausible explanation for the observed patterns. Our results support the view that at least some of the water in the transition zone has been carried into that region by cold subducting slabs.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Long period (10–20,000 s) magnetotelluric (MT) data are being acquired across the continental USA on a quasi-regular grid of ∼70 km spacing as an electromagnetic component of the National Science ...Foundation EarthScope/USArray Program. These data are sensitive to fluids, melts, and other orogenic indicators, and thus provide a valuable complement to other components of EarthScope. We present and interpret results of 3-D MT data inversion from 325 sites acquired from 2006–2011 to provide a regional scale view of electrical resistivity from the middle crust to nearly the mantle transition zone, covering an area from NW Washington to NW Colorado. Beneath the active extensional subprovinces in the south-central region, on average we see a resistive upper crust, and then extensive areas of low resistivity in the lower crust and uppermost mantle. Further below, much of the upper half of the upper mantle appears moderately resistive, then subsequently the lower upper mantle becomes moderately conductive. This column suggests a dynamic process of moderately hydrated and fertile deeper upper mantle upwelling during extension, intersection of that material with the damp solidus causing dehydration and melting, and upward exodus of generated mafic melts to pond and exsolve saline fluids near Moho levels. Lithosphere here is very thin. To the east and northeast, thick sections of resistive lithosphere are imaged under the Wyoming and Medicine Hat Cratons. These are punctuated with numerous electrically conductive sutures presumably containing graphitic or sulfide-bearing meta-sediments deeply underthrust and emplaced during ancient collisions. Below Cascadia, the subducting Juan de Fuca and Gorda lithosphere appears highly resistive. Suspected oceanic lithosphere relicts in the central NW part of the model domain also are resistive, including the accreted “Siletzia” terrane beneath the Coast Ranges and Columbia Embayment, and the seismically fast “slab curtain” beneath eastern Idaho interpreted by others as stranded Farallon plate. Upwelling of deep fluid or melt in the Cascade volcanic arc region manifests as conductive features at several scales. These include quasi-horizontal conductive patches under the arc and fore-arc, likely denoting fluids evolved via breakdown of hydrous minerals in the current down-going slab. In the backarc, low resistivities concentrate in “plumes” connecting into a deeper aesthenospheric layer to the east, consistent with subduction-driven upwelling of hot, hydrated or melted, aesthenospheric mantle. Low resistivities (<10 Ωm) deep beneath the stable cratons suggest higher levels of hydration there, and/or influence of poorly resolved structures outside the array.
•3D modeling of the magnetotelluric data set of the U.S. Transportable Array in northwestern U.S.•Broad image of the electrical resistivity structure of the northwestern U.S.•Imaging the transition from the tectonically active margin to North American craton.•Conductivities are related to fluids and partial melts in the active area.
Stretch‐sensitive Ia afferent monosynaptic connections with motoneurons form the stretch reflex circuit. After nerve transection, Ia afferent synapses and stretch reflexes are permanently lost, even ...after regeneration and reinnervation of muscle by motor and sensory afferents is completed in the periphery. This loss greatly affects full recovery of motor function. However, after nerve crush, reflex muscle forces during stretch do recover after muscle reinnervation and reportedly exceed 140% baseline values. This difference might be explained by structural preservation after crush of Ia afferent synapses on regenerating motoneurons and decreased presynaptic inhibitory control. We tested these possibilities in rats after crushing the tibial nerve (TN), and using Vesicular GLUtamate Transporter 1 (VGLUT1) and the 65 kDa isoform of glutamic acid‐decarboxylase (GAD65) as markers of, respectively, Ia afferent synapses and presynaptic inhibition (P‐boutons) on retrogradely labeled motoneurons. We analyzed motoneurons during regeneration (21 days post crush) and after they reinnervate muscle (3 months). The results demonstrate a significant loss of VGLUT1 terminals on dendrites and cell bodies at both 21 days and 3 months post‐crush. However, in both cellular compartments, the reductions were small compared to those observed after TN full transection. In addition, we found a significant decrease in the number of GAD65 P‐boutons per VGLUT1 terminal and their coverage of VGLUT1 boutons. The results support the hypothesis that better preservation of Ia afferent synapses and a change in presynaptic inhibition could contribute to maintain or even increase the stretch reflex after nerve crush and by difference to nerve transection.
Peripheral nerve transection triggers removal of muscle‐stretch Ia afferent synapses on motoneurons causing the loss of stretch reflexes. However, if the same nerve is crushed, stretch reflexes are enhanced. We demonstrate that after crush, Ia synapses (VGLUT1+) are maintained and facilitated because partial loss of presynaptic inhibition from GAD65 interneurons.
PTC has a great prognosis with a 5-year survival rate approaching 99% when regionalized. To our knowledge, involvement of the hyoid bone is extremely rare and has only been reported twice in ...English-language literature. During the following surveillance of post radioactive iodine treatment, with blood thyroglobulin level and TSH levels, the patient's thyroglobulin has been very low, less than 0.5 ng/mL, on every 3 month laboratory test results, and the level of antithyroglobulin antibodies has been less than 1 ng/mL.
Persistent pulmonary hypertension of the newborn (PPHN) is a failure of pulmonary vascular resistance to decline at birth rapidly. One principal mechanism implicated in PPHN development is ...mitochondrial oxidative stress. Expression and activity of mitochondrial SOD2 (superoxide dismutase) are decreased in PPHN; however, the mechanism remains unknown. Recently, OLA1 (Obg-like ATPase-1) was shown to act as a critical regulator of proteins controlling cell response to stress including Hsp70, an obligate chaperone for SOD2. Here, we investigated whether OLA1 is causally linked to PPHN. Compared with controls, SOD2 expression is reduced in distal-pulmonary arteries (PAs) from patients with PPHN and fetal-lamb models. Disruptions of the SOD2 gene reproduced PPHN phenotypes, manifested by elevated right ventricular systolic pressure, PA-endothelial cells apoptosis, and PA-smooth muscle cells proliferation. Analyses of SOD2 protein dynamics revealed higher ubiquitinated-SOD2 protein levels in PPHN-lambs, suggesting dysregulated protein ubiquitination. OLA1 controls multiple proteostatic mechanisms and is overexpressed in response to stress. We demonstrated that OLA1 acts as a molecular chaperone, and its activity is induced by stress. Strikingly, OLA1 expression is decreased in distal-PAs from PPHN-patients and fetal-lambs. OLA1 deficiency enhanced CHIP affinity for Hsp70-SOD2 complexes, facilitating SOD2 degradation. Consequently, mitochondrial H2O2 formation is impaired, leading to XIAP (X-linked inhibitor of apoptosis) overexpression that suppresses caspase activity in PA-smooth muscle cells, allowing them to survive and proliferate, contributing to PA remodeling. In-vivo, ola1 downregulated SOD2 expression, induced distal-PA remodeling, and right ventricular hypertrophy. We conclude that decreased OLA1 expression accounts for SOD2 downregulation and, therefore, a therapeutic target in PPHN treatments.
A model of electrical conductivity in the mid–mantle transition zone was obtained with improved constraints. An L1‐norm regularization inversion algorithm is proposed here that reduces the influence ...of noisy data on three‐dimensional geomagnetic depth sounding inversion from C‐responses. Here the regularization is implemented by using an L1‐norm to measure the predicted data error, which is normalized by the C‐response covariance, but an L2‐norm is used to measure the regularization term associated with model parameters. The limited‐memory quasi‐Newton method (L‐BFGS) is used to invert for the three‐dimensional electrical conductivity model. The model is discretized by curved rectangular prisms in spherical coordinates. Sensitivity tests show that for good‐quality data contaminated by Gaussian noise, L1 inversion, which could perform as well as L2 inversion, can adequately recover the main features of the electrical conductivity structure within the region of data coverage. When data errors are drawn from an exponential distribution, L1 inversion obtains relatively reliable reconstruction of the electrical structure, even when the noise level is comparable to that of actual C‐responses. C‐responses from 129 low‐latitude and midlatitude geomagnetic observatories are inverted using L1‐norm minimization of the data error. The resulting model reveals an electrically conductive feature in the lower mantle transition zone and upper lower mantle that is broadly coincident with that found in previous studies. The reduced influence of data with large variances on L1‐norm misfits, along with inclusion of responses estimated from more observatories, makes L1 inversion more clearly identify these deep conductive features while identifying previously obscured anoconductive zones. A feature of particular interest is the high electrical conductivity anomaly beneath the Bermuda‐Sargasso Sea region in the mid–mantle transition zone and the uppermost lower mantle. Rock physics analysis indicates that the anomaly is most possibly caused by the wet upwelling material with excessive ~650 K higher temperature, suggesting a narrow tail with a broad head.
Plain‐Language Summary
There remains much to discover regarding the geological characteristics of the Bermuda zone. Specialized scientific instruments deployed in various parts of the world, including the Bermuda zone, have been used to measure geomagnetic and electrical conductivity data for several decades. We used customized computer codes to analyze and model the data recorded by these instruments. We detected a region of very high electrical conductivity in the depth range of 410 to 1,200 km beneath the Bermuda‐Sargasso Sea area. To understand why the electrical conductivity is so high in this region, we also considered recent results from laboratory experiments of the conductivity of materials subjected to high temperature and high pressure. We find that between depths of 520 and 670 km, the studied region is hydrous and also very hot, with temperatures as high as 1,700°C, exceeding by 300°C the average mantle temperature. From depths of 670 to 1,200 km, the mantle is also at least 300°C hotter than normal mantle. The occurrence of these higher temperatures suggests that hot and wet material is rising from the deep mantle beneath the Bermuda‐Sargasso Sea area. This hot upwelling may have accumulated in shallow parts of the mantle as well as the crust, leading to phenomena such as volcanic eruptions and changes in the level of the seafloor in the Bermuda zone.
Key Points
L1‐norm measured data misfit can enhance 3‐D GDS inversion reliability and resolution of mantle electrical structure
New high electrical conductivity anomalies are revealed in the mantle transition zone
The Bermuda high electrical conductivity can be caused by excessively hot and wet upwelling with a narrow tail and a broad head
Prostate cancer (PC) is a multifocal disease. DNA methylation alterations are not restricted to the immediate peritumor environment, but spatially widespread in the adjacent and distant ...histologically normal prostate tissues. In the current study, we utilized high-throughput methylation arrays to identify epigenetic changes in the urine from men with and without cancer.
DNA urine samples were enriched for methylated fragments using MBD methyl-binding antibodies and applied to high density CytoScanHD arrays. Significant loci were validated using quantitative pyrosequencing and binary logistic regression modeling applied to urine sample analyses in a training (n = 83) and validation approach (n = 84). Methylation alterations in prostate tissues using pyrosequencing at the PLA2G16 locus were examined in 38 histologically normal specimens from men with (TA, n = 26) and without (NTA, n = 12) cancer and correlated to gene expression.
Methylation microarrays identified 3,986 loci showing significantly altered methylation in the urine samples from patients with PC compared to those without (TA vs NTA; p<0.01). These loci were then compared against subjects with their prostates removed to exclude non-prostate cell markers yielding 196 significant regions. Multiple CpGs adjacent to PLA2G16 CpG island showed increased methylation in TA compared to NTA (p<0.01) in a large validation study of urine samples. The predictive accuracy of PLA2G16 methylation at CG2 showed the highest predictive value at 0.8 (odds ratio, 1.37; 95% confidence interval, 1.16-1.62; p<0.001). Using a probability cutoff of 0.065, the sensitivity and specificity of the multivariate model was 92% and 35%. When histologically normal prostate tissues/biopsies from patients with PC (TA) were compared to subjects without cancer, significant hypermethylation of PLA2G16 was noted (odds ratio, 1.35; 95% confidence interval, 1.07-1.71; p = 0.01).
PLA2G16 methylation defines an extensive field defect in histologically normal prostate tissue associated with PC. PLA2G16 methylation in urine and prostate tissues can detect the presence of PC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A normative, single-group study was conducted.
To investigate the flexion relaxation phenomenon in the thoraco-lumbopelvic muscles among a pain-free population when moving from an upright to a slump ...sitting posture.
The presence of the flexion relaxation phenomenon (FRP) of the back muscles is well documented at end-range spinal flexion when standing. This phenomenon is commonly found disrupted in low back subjects. However, whether FRP occurs in sitting remains controversial.
The sample consisted of 24 healthy pain-free adults. Surface electromyography was used to measure activity in the superficial lumbar multifidus (SLM), the thoracic erector spinae (TES), and the transverse fibers of the internal oblique (IO) muscles while subjects moved from an erect to a slump sitting posture. An electromagnetic motion-tracking device simultaneously measured thoracolumbar kinematics during this task.
There was a significant decrease in both the SLM and the IO activity when moving from an erect to a slump sitting posture (P = 0.001 and P = 0.004, respectively), indicating the presence of FRP. TES activity was highly variable. While 13 subjects exhibited an increase in activity (P = 0.001), 11 demonstrated a decrease in activity (P = 0.001), indicating the presence of FRP. FRP occurred in the mid-range of spinal flexion for the SLM, IO and TES when present.
The findings show that the SLM and the IO are facilitated in neutral lordotic sitting postures and exhibit FRP at mid range flexion while moving from upright sitting to slump sitting. These findings show that FRP in sitting differs from that in standing. Variable motor patterns (activation or FRP) of the TES were observed. These findings suggest that sustaining mid to end-range flexed sitting spinal postures result in relaxation of the spinal stabilizing muscles.
Osteopathic manipulative medicine (OMM) is an emerging practice in the healthcare field with increasing popularity and evidence-based therapy. Osteopathic manipulative treatments (OMT) include ...hands-on manipulations of different body structures to increase systemic homeostasis and total patient well-being. Indeed, this new realm of the whole patient-based approach is being taught in osteopathic schools around the country, and the osteopathic principles of a mind-body-spirit-based treatment are being instilled in many new Doctor of Osteopathy (D.O.) students. However, despite their proven therapeutic value, there are still many individuals, both in and outside the medical profession, who are unaware (or misinformed) of the therapeutic uses and potential benefits of OMT. Here, we provide a brief introduction to this osteopathic therapeutic approach, focusing on the hands-on techniques that are regularly implemented in the clinical setting. It is becoming increasingly evident that different OMTs can be implemented to enhance patient recovery, both alone and in conjunction with the targeted therapies used in allopathic regimens. Therefore, it may be beneficial to inform the general medical community and educate the public and those associated with the healthcare field about the benefits of using OMT as a treatment modality. OMT is lower-cost, noninvasive, and highly effective in promoting full-body healing by targeting the nervous, lymphatic, immune, and vascular systems. There is a growing body of literature related to osteopathic research and the possible molecular pathways involved in the healing process, and this burgeoning field of medicine is expected to increase in value in the healthcare field. This brief review article explains the frequently utilized OMT modalities and their recognized therapeutic benefits, which underscore the need to understand the possible molecular mechanisms and circulating biomarkers linked to the systemic benefits of osteopathic medicine.
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