216 research outputs found

    Characterization of Multiple Groups of Data

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    In this paper we propose a new approach for computing characterizations of sets of data by means of partially defined Boolean functions. The main objective is to provide minimal sets of characters that allows the user to discriminate groups of Boolean data representing individuals described by means of presence or absence of characters. Compared to previous approaches, our algorithms are more efficient and are able to compute complete sets of solutions, which may be useful according to our underlying application domain in plant biology

    Relationship between ankle brachial index and arterial remodeling in pseudoxanthoma elasticum

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    ObjectivesPseudoxanthoma elasticum (PXE) is an inherited metabolic disease characterized by elastic fiber fragmentation and calcification in the cutaneous, ophthalmologic, and vascular tissues. Cardiovascular manifestations such as peripheral arterial disease (PAD) are frequent in PXE. Because of the changes in the elastic properties and medial calcification of the arterial wall in PXE, the impact of the arterial remodeling on the ankle brachial index (ABI), a well-established diagnostic method for the detection and follow-up of PAD, remains to be determined in this disease. Methods This was a cross-sectional, comparative, open study, which took place at the PXE Consultation Center, University Hospital of Angers. The subjects were 53 patients (mean age, 49 ± 14 years; 35 females) with PXE clinically proven on the basis of established criteria (skin changes, angioid streaks, and skin biopsy). The ABI at rest, symptoms of intermittent claudication (IC), carotid intima-media thickness (IMT), carotid-femoral pulse wave velocity (c-f PWV), compliance (CC), and β stiffness index were measured in a single-center cohort. Results Forty-five percent of the PXE patients had an ABI ≤0.90, but only one patient had an ABI >1.40. IC was found in 23% of the patients with an ABI ≤0.90. There were no significant differences between the patients with a low and normal ABI in terms of IMT (P = .566) or β stiffness index (P = .194), but differences were significant for c-f PWV (P = .010) and CC (P = .011). Adjusted multivariate linear regression for the Framingham-Laurier score showed that patients with a low ABI had less compliant carotid arteries (B = 0.318, P = .039). Conclusions PAD detected by a low ABI is very frequent in PXE, although with limited prevalence of symptomatic claudication. Unexpectedly, ABI was low in such calcifying PAD and associated with lower CC, independently of atherosclerosis risk factors. These findings demonstrate that PXE represents a unique monogenic model of PAD in which the specific arterial wall remodeling could change the diagnostic value of the ABI to detect PAD

    ABCC6 is a basolateral plasma membrane protein

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    RATIONALE:: ABCC6 plays a crucial role in ectopic calcification; mutations of the gene cause pseudoxanthoma elasticum and general arterial calcification of infancy. To elucidate the role of ABCC6 in cellular physiology and disease, it is crucial to establish the exact subcellular localization of the native ABCC6 protein. OBJECTIVE:: In a recent article in Circulation Research, ABCC6 was reported to localize to the mitochondria-associated membrane and not the plasma membrane. As the suggested mitochondrial localization is inconsistent with published data and the presumed role of ABCC6, we performed experiments to determine the cellular localization of ABCC6 in its physiological environment. METHODS AND RESULTS:: We performed immunofluorescent labeling of frozen mouse and human liver sections, as well as primary hepatocytes. We used several different antibodies recognizing human and mouse ABCC6. Our results unequivocally show that ABCC6 is in the basolateral membrane of hepatocytes and is not associated with the mitochondria, mitochondria-associated membrane, or the endoplasmic reticulum. CONCLUSIONS:: Our findings support the model that ABCC6 is in the basolateral membrane, mediating the sinusoidal efflux of a metabolite from the hepatocytes to systemic circulation. © 2013 American Heart Association, Inc

    The vascular phenotype in Pseudoxanthoma elasticum and related disorders: contribution of a genetic disease to the understanding of vascular calcification

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    Vascular calcification is a complex and dynamic process occurring in various physiological conditions such as aging and exercise or in acquired metabolic disorders like diabetes or chronic renal insufficiency. Arterial calcifications are also observed in several genetic diseases revealing the important role of unbalanced or defective anti- or pro-calcifying factors. Pseudoxanthoma elasticum (PXE) is an inherited disease (OMIM 264800) characterized by elastic fiber fragmentation and calcification in various soft conjunctive tissues including the skin, eyes, and arterial media. The PXE disease results from mutations in the ABCC6 gene, encoding an ATP-binding cassette transporter primarily expressed in the liver, kidneys suggesting that it is a prototypic metabolic soft-tissue calcifying disease of genetic origin. The clinical expression of the PXE arterial disease is characterized by an increased risk for coronary (myocardial infarction), cerebral (aneurysm and stroke), and lower limb peripheral artery disease. However, the structural and functional changes in the arterial wall induced by PXE are still unexplained. The use of a recombinant mouse model inactivated for the Abcc6 gene is an important tool for the understanding of the PXE pathophysiology although the vascular impact in this model remains limited to date. Overlapping of the PXE phenotype with other inherited calcifying diseases could bring important informations to our comprehension of the PXE disease

    DEMOCRATIC TRANSITION AND REFLECTION ON INDONESIA'S EFFORTS TO ENCOURAGE DEMOCRATIZATION IN MYANMAR

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    This paper aims to analyze the motives and forms of Indonesia’s effort towards Myanmar in promoting democratization. To achieve these objectives, described the historical aspects of Indonesia-Myanmar relations, democratic transition in both countries, and other forms of Indonesian support for Myanmar in encouraging democratization. Qualitative methods is used in this study to collect and analyze data from interviews and literature studies. Based on this research, found that Indonesia's support for Myanmar in encouraging democratization was influenced by the historical aspects of bilateral relations between Indonesia and Myanmar, the success of Indonesia's transition to democracy, and the similarities of socio-cultural characteristics in both countries. Indonesia's foreign policy towards Myanmar in supporting democratization is done bilaterally, regionally within ASEAN, and multilaterally within UN forums. The principle of active and independent foreign policy and ASEAN norms become the guidance for Indonesia in supporting democratization of Myanmar

    Quantification of the Calcification Phenotype of Abcc6-Deficient Mice with Microcomputed Tomography

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    Pseudoxanthoma elasticum in humans and dystrophic cardiac calcification in mice are heritable disorders characterized by dystrophic calcification of soft connective tissues related to the defective function of the ABCC6 (human)/Abcc6 (mouse) transporter. Of particular interest is the finding of calcified vibrissae in Abcc6−/− mice, which facilitates the study of dystrophic calcification by histological techniques. We aimed to determine whether mice prone to dystrophic cardiac calcification (C3H/HeOuJ and DBA/2J strains) presented similar vibrissae changes and to evaluate the value of microcomputed tomography to quantify the extent of mystacial vibrissae calcifications. These calcifications were absent in DBA/2J and C57BL/6J control mice. In both Abcc6−/− and C3H/HeOuJ mice, calcifications progressed in a caudal-rostral direction with aging. However, the calcification process was delayed in C3H/HeOuJ mice, indicating an incomplete expression of the calcification phenotype. We also found that the calcification process in the cephalic region was not limited to mystacial vibrissae but was also present in other periorbital sensorial vibrissae. The vibrissae calcification was circular and encompassed the medial region of the vibrissae capsule, adjacent to the ring and cavernous sinuses (the areas adjacent to blood and lymphatic vessels). Collectively, our findings confirm that Abcc6 acts as an inhibitor of spontaneous chronic mineralization and that microcomputed tomography is a valuable noninvasive tool for the assessment of the calcification phenotype in Abcc6-deficient mice

    Expression and In Vivo Rescue of Human ABCC6 Disease-Causing Mutants in Mouse Liver

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    Loss-of-function mutations in ABCC6 can cause chronic or acute forms of dystrophic mineralization described in disease models such as pseudoxanthoma elasticum (OMIM 26480) in human and dystrophic cardiac calcification in mice. The ABCC6 protein is a large membrane-embedded organic anion transporter primarily found in the plasma membrane of hepatocytes. We have established a complex experimental strategy to determine the structural and functional consequences of disease-causing mutations in the human ABCC6. The major aim of our study was to identify mutants with preserved transport activity but failure in intracellular targeting. Five missense mutations were investigated: R1138Q, V1298F, R1314W, G1321S and R1339C. Using in vitro assays, we have identified two variants; R1138Q and R1314W that retained significant transport activity. All mutants were transiently expressed in vivo, in mouse liver via hydrodynamic tail vein injections. The inactive V1298F was the only mutant that showed normal cellular localization in liver hepatocytes while the other mutants showed mostly intracellular accumulation indicating abnormal trafficking. As both R1138Q and R1314W displayed endoplasmic reticulum localization, we tested whether 4-phenylbutyrate (4-PBA), a drug approved for clinical use, could restore their intracellular trafficking to the plasma membrane in MDCKII and mouse liver. The cellular localization of R1314W was significantly improved by 4-PBA treatment, thus potentially rescuing its physiological function. Our work demonstrates the feasibility of the in vivo rescue of cellular maturation of some ABCC6 mutants in physiological conditions very similar to the biology of the fully differentiated human liver and could have future human therapeutic application

    Vitamin K supplementation increases vitamin K tissue levels but fails to counteract ectopic calcification in a mouse model for pseudoxanthoma elasticum

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    Pseudoxanthoma elasticum (PXE) is an autosomal recessive disorder in which calcification of connective tissue leads to pathology in skin, eye and blood vessels. PXE is caused by mutations in ABCC6. High expression of this transporter in the basolateral hepatocyte membrane suggests that it secretes an as-yet elusive factor into the circulation which prevents ectopic calcification. Utilizing our Abcc6−/− mouse model for PXE, we tested the hypothesis that this factor is vitamin K (precursor) (Borst et al. 2008, Cell Cycle). For 3 months, Abcc6−/− and wild-type mice were put on diets containing either the minimum dose of vitamin K required for normal blood coagulation or a dose that was 100 times higher. Vitamin K was supplied as menaquinone-7 (MK-7). Ectopic calcification was monitored in vivo by monthly micro-CT scans of the snout, as the PXE mouse model develops a characteristic connective tissue mineralization at the base of the whiskers. In addition, calcification of kidney arteries was measured by histology. Results show that supplemental MK-7 had no effect on ectopic calcification in Abcc6−/− mice. MK-7 supplementation increased vitamin K levels (in skin, heart and brain) in wild-type and in Abcc6−/− mice. Vitamin K tissue levels did not depend on Abcc6 genotype. In conclusion, dietary MK-7 supplementation increased vitamin K tissue levels in the PXE mouse model but failed to counteract ectopic calcification. Hence, we obtained no support for the hypothesis that Abcc6 transports vitamin K and that PXE can be cured by increasing tissue levels of vitamin K
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