Results 1 - 10 of 524
Results 1 - 10 of 524. Search took: 0.019 seconds
|Sort by: date | relevance|
[en] Vitamin B12 deficiency is one of the common conditions in the elderly population leading to confusion, depression, memory loss and balance problems. Unfortunately there is no gold standard test for the diagnosis of cobalamin deficiency and a wide range of variation in reference levels according to country, and laboratory assay used. This poses a problem in diagnosing this condition making it a commonly misdiagnosed medical entity. There is current emphasis on need for clearer guidelines and much research is still being done to pave ways to determine better reference values for serum B12 and other screening tests. It is advised that screening methods are used adjunctively for the purpose of screening individuals. (author)
[en] Myostatin, a Transforming Growth Factor-beta (TGF-β) super-family member, has previously been shown to negatively regulate satellite cell activation and self-renewal. However, to date the mechanism behind Myostatin function in satellite cell biology is not known. Here we show that Myostatin signals via a Pax7-dependent mechanism to regulate satellite cell self-renewal. While excess Myostatin inhibited Pax7 expression via ERK1/2 signaling, an increase in Pax7 expression was observed following both genetic inactivation and functional antagonism of Myostatin. As a result, we show that either blocking or inactivating Myostatin enhances the partitioning of the fusion-incompetent self-renewed satellite cell lineage (high Pax7 expression, low MyoD expression) from the pool of actively proliferating myogenic precursor cells. Consistent with this result, over-expression of Pax7 in C2C12 myogenic cells resulted in increased self-renewal through a mechanism which slowed both myogenic proliferation and differentiation. Taken together, these results suggest that increased expression of Pax7 promotes satellite cell self-renewal, and furthermore Myostatin may control the process of satellite cell self-renewal through regulation of Pax7. Thus we speculate that, in addition to the intrinsic factors (such as Pax7), extrinsic factors both positive and negative in nature, will play a major role in determining the stemness of skeletal muscle satellite cells
[en] Graphical abstract: - Highlights: • Temperature dependence of heat capacity of vitamin B12 has been measured by precision adiabatic vacuum calorimetry. • The thermodynamic functions of the vitamin B12 have been determined for the range from T → 0 to 343 K. • The character of heterodynamics of structure was detected. • The thermal stability of cyanocobalamin was studied by differential scanning calorimetry. - Abstract: In the present work temperature dependence of heat capacity of vitamin B12 (cyanocobalamin) has been measured for the first time in the range from 6 to 343 K by precision adiabatic vacuum calorimetry. Based on the experimental data, the thermodynamic functions of the vitamin B12, namely, the heat capacity, enthalpy H°(T) − H°(0), entropy S°(T) − S°(0) and Gibbs function G°(T) − H°(0) have been determined for the range from T → 0 to 343 K. The value of the fractal dimension D in the function of multifractal generalization of Debye's theory of the heat capacity of solids was estimated and the character of heterodynamics of structure was detected. The thermal stability of cyanocobalamin was also studied by differential scanning calorimetry
[en] Understanding what drives variation in the abundance of organisms is fundamental to evolutionary ecology and wildlife management. Yet despite its importance, there is still great uncertainty about the main factors influencing variation in vertebrate abundance across taxa. We believe valuable knowledge and increased predictive power could be gained by taking into account both the intrinsic factors of species and the extrinsic factors related to environmental surroundings in the commonly cited RQ model, which provides a simple conceptual framework valid at both the interspecific and the intraspecific scales. Approaches comparing studies undertaken at different spatial and taxonomic scales could be key to our ability to better predict abundance, and thanks to the increased availability of population size data, global geographic datasets, and improved comparative methods, there might be unprecedented opportunities to (1) gain a greater understanding of vertebrate abundance patterns and (2) test existing theories on free-ranging animals.
[en] Cyclic voltammetry (CV) and square wave adsorptive stripping voltammetry (SWAdSV) were used to investigate the performance of an ex situ plated bismuth-film electrode (BiFE) employed to study the electrochemical behavior and the electroanalytical determination of vitamin B12. Two pH-dependent reversible peaks were observed for the B12r–B12s (Co(II)–Co(I)) couple after pre-concentration of vitamin B12 at −1.2 V for 30 s. An adsorption-controlled reaction rate with one electron involved in the electrochemical step was observed for the mechanism implicated. The calibration curve obtained in a Britton–Robinson solution at pH 12.0 was linear in the concentration range of 0.100–1.000 μmol L−1 (r = 0.9980). The detection limit was found to be 33.1 nmol L−1. The electrode was successfully employed for the determination of vitamin B12 in two pharmaceutical products. The electrode performance was compared with those of modified and unmodified electrodes as well as with the UV–vis spectrophotometric method.
[en] This invention concerns a composition including a labelled compound, and the vitamin B 12. This vitamin gives a red colour to the solution and stabilize it radiochemically, allowing to transport the solution at ambient temperature and a storage at 4 degrees celsius. (N.C.). 5 refs
[en] Although eggshell thinning has been described mainly in the context of environmental pollution, it can also be the effect of reproductive changes induced by a developing embryo. On the basis of a literature survey of 25 bird species (26 published papers) we reviewed data on embryo-induced eggshell thinning (EET) in three groups of birds: precocials, semi-precocials and altricials. The average EET at the equator of the eggs was 6.4% (median = 4.7%). Our review did not confirm a general prediction of elevated EET at the egg equator in precocial species: altricial birds exhibited the highest EET (average = 12.0%), followed by precocials (7.6%) and semi-precocials (4.2%). We make certain critical recommendations based on the results of this study. Studies aiming to assess variation in eggshell thickness should examine intrinsic factors affecting shell properties of avian eggs, like thickness, which are the result of anatomical or reproductive changes. - Highlights: • We reviewed literature data on embryo-induced eggshell thinning (EET) in birds. • The average EET at the equator of the eggs of 25 bird species was 6.4%. • Altricial birds exhibited the highest EET, followed by precocials and semi-precocials. • All studies on variation in eggshell thickness should take EET into consideration. - Our study emphasizes the need to consider embryo-induced eggshell thinning in studies aiming to assess variation in eggshell thickness
[en] Vitamin B12 (cobalamin) is an essential nutrient that is only obtained from foods of animal origin, such as meat, eggs and dairy products. Vitamin B12 plays an important role in DNA synthesis and neurological function. Thus its deficiency can lead to several neurological symptoms such as memory loss, dizziness and in severe cases may lead to dementia. Many factors can cause or lead to vitamin B-12 deficiency. Among these are malabsorption, several gastron intestinal problems (i.e. celiac disease, Crobn's disease) and gastrointestinal surgeries. diagnosis of vitamin B-12 status depends commonly on serum vitamin B12 which is nonspecific tool for the deficiency. Other more specific tests, which reflect true deficiency, include serum and urine methylmalonic aci de, total serum homocysteine and serum holotranscobalamin. Vitamin B12 deficiency is a worldwide public health problem; epidemiological studies showed that its prevalence in industrialized countries ranges from 5-60% of the population depending on the used cutoff point of cobalamin level. In Jordan, many reports were published on vitamin B 12 deficiency. However, these reports gave different results of its prevalence ranging from 16-48% depending on the serum vitamin B12 cutoff point used. A recent study showed a prevalence of true deficiency of 32.7% based on measuring both serum vitamin B12 level and plasma methylmalonic acid. (authors).
[en] Intrinsic radioprotection is offered by almost all types of biomolecules, though its degree varies. The different factors which influence it are: types of radiation; dose and dose rate; dose reduction factor; concentration of radioprotector; radioprotective factor; pH, ionic strength, solvent and temperature; oxic, hypoxic and anoxic condition; radiosensitivity of radioprotectors; distance between functional groups and bond energy; radius of gyration and biomolecular configuration; surface area and dose of inactivation; configuration of backbone and supercoiling biomolecules; packing and condensation of biomolecules. etc. The present review elucidates their role in intrinsic radioprotection. (author)
[en] The performance of amended micrometric iron particles (Fe0) in trimetallic systems for the removal of aqueous diclofenac (DF) was investigated. Tested additive metals were Pd, Cu and Ni. Trimetallic systems were shown superior to Fe0 for aqueous DF removal both under oxic and anoxic conditions. The extent of DF removal varied with (i) the combination of the additives, (ii) the order of plating on Fe0 surface, (iii) the availability of dissolved oxygen and (iv) the presence of MnO2. In comparison with previous results for bimetallic systems: (i) DF reduction products were observed under anoxic conditions for all trimetallic systems and only in some bimetallic systems; and (ii) under oxic conditions, DF reaction products were only observed in CuPdFe system. This was accredited to the intrinsic and electronic properties of the involved metals. Rapid DF removal was mainly attributed to the capacity of additive metals to accelerate Fe0 corrosion and thus producing more atomic hydrogen within the porous iron oxide layers. This promoted catalytic hydrodehalogenation was clearly apparent in systems where reductive transformation products were identified (e.g. PdCuFe). Recycling experiments using PdCuFe showed a continuous reactivity even after 4 successive cycles under anoxic conditions, however, under oxic conditions, a serious reactivity loss was noticed.(author)