1,847 research outputs found
Assessing dolomite surface reactivity at temperatures from 40 to 120 degrees C by hydrothermal atomic force microscopy
This study investigated the reactivity of the (1 0 4) dolomite surface in the system MgCO3âCaCO3âNaClâH2O via a suite of aqueous solutionâdolomite hydrothermal atomic force microscopy interaction experiments at temperatures from 40 to 120 °C, pH ranging from 4 to 8, pressures up to 5 bars, and over a wide range of aqueous fluid saturation state. Dolomite dissolution was observed in the presence of undersaturated aqueous fluids. Dissolution produced crystallographically well defined etch pits, consistent with the stoichiometric release of ordered lattice cations. In low to moderately saturated fluids, dolomite growth began by the growth of one or two layers of carbonate (layer height <3 Ă
) which morphologically reproduced the initial surface features, resembling the template effect as previously described by Astilleros et al. (2003, 2006) and Freij et al. (2004). Further growth was strongly inhibited and did not show any systematic crystallographically orientated growth morphologies. At aqueous fluid saturation states exceeding 500, nucleation and growth was observed on the dolomite surfaces at moderate rates, but these did not exhibit the characteristic dolomite crystallographic orientation after the growth of several layers. Taken together these observations suggest that the direct precipitation of dolomite from aqueous solution is disfavored at temperatures to at least 120 °C due to the poisoning of the dolomite surface for further growth by the precipitation of one to four CaâMg carbonate layers on these surfaces
New insights into atypical Alzheimer's disease in the era of biomarkers
Most patients with Alzheimer's disease present with amnestic problems; however, a substantial proportion, over-represented in young-onset cases, have atypical phenotypes including predominant visual, language, executive, behavioural, or motor dysfunction. In the past, these individuals often received a late diagnosis; however, availability of CSF and PET biomarkers of Alzheimer's disease pathologies and incorporation of atypical forms of Alzheimer's disease into new diagnostic criteria increasingly allows them to be more confidently diagnosed early in their illness. This early diagnosis in turn allows patients to be offered tailored information, appropriate care and support, and individualised treatment plans. These advances will provide improved access to clinical trials, which often exclude atypical phenotypes. Research into atypical Alzheimer's disease has revealed previously unrecognised neuropathological heterogeneity across the Alzheimer's disease spectrum. Neuroimaging, genetic, biomarker, and basic science studies are providing key insights into the factors that might drive selective vulnerability of differing brain networks, with potential mechanistic implications for understanding typical late-onset Alzheimer's disease
Prepubertal unilateral gynecomastia: a report of two cases
Item does not contain fulltextBACKGROUND: Gynecomastia is defined as the presence of excessive breast tissue in males, which can appear unilateral or bilateral. Bilateral gynecomastia is frequently found in the neonatal period, early in puberty, and with increasing age. Prepubertal unilateral gynecomastia in the absence of endocrine abnormalities is extremely rare, with only a few cases in literature. METHODS: We report the cases of two otherwise healthy boys of 8 and 11 years old with unilateral breast masses. No abnormalities were found on ultrasonography and all endocrine parameters were within normal limits. Treatment consisted of peripheral liposuction followed by subcutaneous partial resection of the gland, conducted through an infra-areolar incision. Results : Microscopy of the subcutaneous mastectomy specimen revealed gynecomastia without signs of malignancy. Postoperative course of both patients was uncomplicated, with no signs of recurrence of breast tissue. CONCLUSIONS: Atypical presentations of gynecomastia are often not recognized, with little attention to breast development in prepubertal non-obese children. Since prepubertal gynecomastia could be a sign of possible underlying diseases, a thorough examination and further research is recommended. If there is no causal treatment, surgical resection is the therapy of first choice. Peripheral liposuction and surgical resection of the gland tissue are the mainstay of treatment. In summary, we describe two cases of prepubertal unilateral gynecomastia with a normal endocrine workup. Further research is needed to establish the pathophysiologic mechanisms of prepubertal gynecomastia, since underlying etiology in most cases remains unclear
Borrelia recurrentis employs a novel multifunctional surface protein with anti-complement, anti-opsonic and invasive potential to escape innate immunity
Borrelia recurrentis, the etiologic agent of louse-borne relapsing fever in humans, has evolved strategies, including antigenic variation, to evade immune defence, thereby causing severe diseases with high mortality rates. Here we identify for the first time a multifunctional surface lipoprotein of B. recurrentis, termed HcpA, and demonstrate that it binds human complement regulators, Factor H, CFHR-1, and simultaneously, the host protease plasminogen. Cell surface bound factor H was found to retain its activity and to confer resistance to complement attack. Moreover, ectopic expression of HcpA in a B. burgdorferi B313 strain, deficient in Factor H binding proteins, protected the transformed spirochetes from complement-mediated killing. Furthermore, HcpA-bound plasminogen/plasmin endows B. recurrentis with the potential to resist opsonization and to degrade extracellular matrix components. Together, the present study underscores the high virulence potential of B. recurrentis. The elucidation of the molecular basis underlying the versatile strategies of B. recurrentis to escape innate immunity and to persist in human tissues, including the brain, may help to understand the pathological processes underlying louse-borne relapsing fever
Improvement of pain and regional osteoporotic changes in the foot and ankle by low-dose bisphosphonate therapy for complex regional pain syndrome type I: a case series
<p>Abstract</p> <p>Introduction</p> <p>Complex regional pain syndrome is characterized by pain, allodynia, hyperalgesia, edema, signs of vasomotor instability, movement disorders, joint stiffness, and regional osteopenia. It is recognized to be difficult to treat, despite various methods of treatment, including physiotherapy, calcitonin, corticosteroids, sympathetic blockade, and nonsteroidal anti-inflammatory drugs. Pathophysiologically, complex regional pain syndrome reveals enhanced regional bone resorption and high bone turnover, and so bisphosphonates, which have a potent inhibitory effect on bone resorption, were proposed for the treatment of complex regional pain syndrome.</p> <p>Case presentation</p> <p>A 48-year-old Japanese man with complex regional pain syndrome type I had severe right ankle pain with a visual analog scale score of 59 out of 100 regardless of treatment with physiotherapy and nonsteroidal anti-inflammatory drugs for five months. Radiographs showed marked regional osteoporotic changes and bone scintigraphy revealed a marked increase in radioactivity in his ankle. One month after the start of oral administration of risedronate (2.5 mg per day), his bone pain had fallen from a VAS score of 59 out of 100 to 18 out of 100. Bone scintigraphy at 12 months showed a marked reduction in radioactivity to a level comparable to that in his normal, left ankle. On the basis of these results, the treatment was discontinued at 15 months. At 32 months, our patient had almost no pain and radiographic findings revealed that the regional osteoporotic change had returned to normal.</p> <p>A second 48-year-old Japanese man with complex regional pain syndrome type I had severe right foot pain with a visual analog scale score of 83 out of 100 regardless of treatment with physiotherapy and nonsteroidal anti-inflammatory drugs for nine months. Radiographs showed regional osteoporotic change in his phalanges, metatarsals, and tarsals, and bone scintigraphy revealed a marked increase in radioactivity in his foot. One month after the start of oral administration of alendronate (35 mg per week), his bone pain had fallen from a visual analog scale score of 83 out of 100 to 30 out of 100 and, at nine months, was further reduced to 3 out of 100. The treatment was discontinued at 15 months because of successful pain reduction. At 30 months, our patient had no pain and the radiographic findings revealed marked improvement in regional osteoporotic changes.</p> <p>Conclusions</p> <p>We believe low-dose oral administration of bisphosphonate is worth considering for the treatment of idiopathic complex regional pain syndrome type I accompanied by regional osteoporotic change.</p
Evidence maps and evidence gaps: evidence review mapping as a method for collating and appraising evidence reviews to inform research and policy
Evidence reviews are a key mechanism for incorporating extensive, complex and specialised evidence into policy and practice, and in guiding future research. However, evidence reviews vary in scope and methodological rigour, creating several risks for decision-makers: decisions may be informed by less reliable reviews; apparently conflicting interpretations of evidence may obfuscate decisions; and low quality reviews may create the perception that a topic has been adequately addressed, deterring new syntheses (cryptic evidence gaps). We present a new approach, evidence review mapping, designed to produce a visual representation and critical assessment of the review landscape for a particular environmental topic or question. By systematically selecting and describing the scope and rigour of each review, this helps guide non-specialists to the most relevant and methodologically reliable reviews. The map can also direct future research through the identification of evidence gaps (whether cryptic or otherwise) and redundancy (multiple reviews on similar questions). We consider evidence review mapping a complementary approach to systematic reviews and systematic maps of primary literature and an important tool for facilitating evidence-based decision-making and research efficiency
Measurement of the top quark mass using the matrix element technique in dilepton final states
We present a measurement of the top quark mass in ppÂŻ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of 9.7ââfbâ1. The matrix element technique is applied to ttÂŻ events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the lepton+jets final state of ttÂŻ decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of mt=173.93±1.84ââGeV
Search for rare quark-annihilation decays, B --> Ds(*) Phi
We report on searches for B- --> Ds- Phi and B- --> Ds*- Phi. In the context
of the Standard Model, these decays are expected to be highly suppressed since
they proceed through annihilation of the b and u-bar quarks in the B- meson.
Our results are based on 234 million Upsilon(4S) --> B Bbar decays collected
with the BABAR detector at SLAC. We find no evidence for these decays, and we
set Bayesian 90% confidence level upper limits on the branching fractions BF(B-
--> Ds- Phi) Ds*- Phi)<1.2x10^(-5). These results
are consistent with Standard Model expectations.Comment: 8 pages, 3 postscript figues, submitted to Phys. Rev. D (Rapid
Communications
The relationship between vitamin D status and muscle strength in young healthy adults from sunny climate countries currently living in the northeast of Scotland
Summary: The current study examined the relationship between vitamin D status and muscle strength in young healthy adults: residents (>6 months) and newcomers (0â3 months), originally from sunny climate countries but currently living in the northeast of Scotland. Our longitudinal data found a positive, albeit small, relationship between vitamin D status and knee extensor isometric strength. Introduction: Vitamin D has been suggested to play a role in muscle health and function, but studies so far have been primarily in older populations for falls prevention and subsequent risk of fractures. Methods: Vitamin D status was assessed in a healthy young adults from sunny climate countries (n = 71, aged 19â42 years) with 56% seen within 3 months of arriving in Aberdeen [newcomers; median (range) time living in the UK = 2 months (9â105 days)] and the remainder resident for >6 months [residents; 23 months (6â121 months)]. Participants attended visits every 3 months for 15 months. At each visit, fasted blood samples were collected for analysis of serum 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), carboxy-terminal collagen crosslinks (CTX) and N-terminal propeptide of type I collagen (P1NP). Maximal voluntary contractions (MVC) were performed for grip strength (both arms) and for maximal isometric strength of the knee extensors (right knee). Results: There were small seasonal variations in 25(OH)D concentrations within the newcomers and residents, but no seasonal variation in bone turnover markers. There was a positive, albeit small, association between 25(OH)D and knee extensor maximal isometric strength. Mixed modelling predicted that for each 1 nmol/L increase in 25(OH)D, peak torque would increase by 1 Nm (p = 0.04). Conclusions: This study suggests that vitamin D may be important for muscle health in young adults migrating from sunnier climates to high latitudes, yet the potential effect is small
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