UMLS:C0162871 - FACTA Search

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Query: UMLS:C0162871 (abdominal aortic aneurysm)
8,664 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Medial degeneration of extracellular matrix (ECM) proteins in the wall of abdominal aortas results in smooth muscle cell destruction, a loss of architectural integrity, and abdominal aortic aneurysm (AAA) formation. It has been theorized that an imbalance between proteinases and their naturally occurring inhibitors is the cause of these observed histologic abnormalities. Therefore, the purpose of this investigation was to determine if differences in the matrix metalloproteinase (MMP) -2 and -9, tissue inhibitor of metalloproteinase-1 (TIMP-1), tissue-type plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA) protein and activity levels existed between infrarenal AAA and normal abdominal aortic tissue specimens. Between November 1995 and January 1997, 10 patients undergoing elective infrarenal AAA repair had a portion of their aneurysm walls snap frozen in liquid nitrogen and processed for subsequent western blot or zymographic analysis. Tissue specimens from 6 normal abdominal aortas obtained from fresh cadaver specimens were similarly processed and served as controls. Protein levels for MMP-2, MMP-9, TIMP-1, uPA, and tPA were analyzed by western blotting. The degree of MMP-2 and MMP-9 gelatinolytic activity was analyzed by zymography. Detection and immunolocalization for MMP-2, MMP-9 and CD68 was performed on tissue sections of AAA and normal infrarenal abdominal aortas fixed in 10% formalin. MMP-9 and tPA protein levels were increased in AAAs compared to controls by western blotting. However, uPA levels were slightly increased in controls. No differences in TIMP-1 protein levels were identified. Similarly, zymography demonstrated increased MMP-2 and MMP-9 gelatinolytic activity in AAAs compared to controls (p < or = 0.05). CD68-positive cells (macrophages) in the adventitia and media demonstrated immunoreactivity to MMP-9. This investigation demonstrated increased MMP-9 proteinase activity and tPA protein levels in the walls of AAAs, as well as inflammatory leukocyte invasion of the adventitia and media compared to controls. These data suggest that leukocyte-derived MMP-9 is associated with aortic wall degeneration and aneurysm formation. Furthermore, activation of MMP-9 may be caused by increased tPA levels in the walls of AAAs.
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PMID:Matrix metalloproteinase expressions in arteriosclerotic aneurysmal disease. 1270 18

The ZraR (HydG) protein is a 441-amino-acid protein with three functional domains and is homologous to the general nitrogen-regulatory protein NtrC that regulates nitrogen assimilation in many bacteria. The AAA and DNA-binding domains (residues 141-441) of the ZraR protein from Salmonella typhimurium were crystallized using the sitting-drop vapour-diffusion method. X-ray diffraction data from the native crystal have been collected to 3.0 A resolution. Initial phasing was successfully performed by the SIRAS method using derivativatized crystals soaked in 1 mM ethylmercuric phosphate. Preliminary structural analysis shows the presence of a hexamer in the asymmetric unit. Model building is in progress.
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PMID:X-ray crystallographic characterization and phasing of an NtrC homologue. 1292 4

Magnetic susceptibilities of spin-1/2 systems of orthorhombic and higher crystal symmetries have been numerically investigated while taking possible anisotropy in the coupling constants along different crystal axes into account. The work relies on the magnon-based theory of ferromagnetic (FM) and antiferromagnetic (AFM) crystal systems of types FFF, AFF, AAF, and AAA [J. Chem. Phys. 111, 9009 (1999)]. The AAF crystal, in particular, shows interesting changes in the temperature dependence of magnetic susceptibility when the ferromagnetic exchange coupling constant is varied. We especially show that the susceptibility anomalies of molecular crystals fit naturally within the framework of the extended magnon-theoretical formalism, and do not necessarily imply a FM --> AFM or a reverse phase transition. A real system, molecular crystal of 2,4,6-triphenylverdazyl (2,4,6-TPV), has been investigated here. It was previously interpreted as an AAF system from observed susceptibility data [Tomiyoshi et al., Phys. Rev. B 49, 16031 (1994)]. The trend of the temperature dependence of magnetic susceptibility studied in the present work also indicates that the crystal belongs to the AAF category with a less prominent FM exchange coupling constant. To reinforce our conclusions, we have adopted a two-pronged strategy. First, the geometry of the 2,4,6-TPV monomer has been optimized here by ab initio unrestricted Hartree-Fock (UHF) calculations using the STO-3G basis set. The optimized geometry is almost planar. A subsequent calculation has been carried out with the phenyl rings twisted out of the plane of the nitrogen atoms. The STO-3G optimized geometry, and the same geometry except for the twisted phenyl rings, have been used to perform ab initio coupled-cluster (UCCSD-T) calculations with the same basis, and UHF as well as density-functional (UB3LYP) calculations using the 6-31G basis set. The calculated data can easily rationalize the twists while the species remains in crystal. The magnetic category of the crystal has been unambiguously confirmed as AFA from ab initio UHF and UB3LYP calculations of the total energy in different spin states of dimers and trimers along the crystal axes. The computed energy values, however, fail to yield accurate estimates of the exchange coupling constants Ja, Jb, and Jc, because the latter are on the order of 1kBK corresponding to energy differences on the order of 10(-6) hartree between different spin states. In the second approach, the observed features of the susceptibility minimum and maximum have been used to determine the best values of the exchange coupling constants from the theoretical formulas for an anisotropic AFA crystal. The AFM (Ja and Jc) and FM (Jb) exchange coupling constants and the Neel temperature (TN) found from this analysis correspond to Ja + Jc = -1.05 kBK, Jb = 1.35 kBK, and TN = 1.75 K. The calculated J values significantly differ from those estimated from a linear Heisenberg chain model, but generate a susceptibility versus temperature graph that mimics the experimental plot.
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PMID:On the variation of magnetic susceptibility of a molecular crystal with temperature: the 2,4,6-triphenylverdazyl system. 1526 78

Transcriptional activation by the E.coli NtrC protein can occur via DNA looping between a DNA-bound activator and the target sigma(54) RNA polymerase. NtrC forms an octamer on DNA that is capable of binding two DNA molecules. Its ATPase activity is required for open complex formation. Geometric requirements for activation were assessed using a library of DNA bending sequences created by random ligation of A-tract oligonucleotides, as well as several designed sequences. Thirty random or designed sequences with a variety of DNA lengths and bending geometries were cloned in plasmids, and the library was used to replace the spacer between the NtrC binding sites and the core glnAp2 promoter. The activity of each promoter construct under nitrogen limitation was determined in vivo, in a lambda phage lacZ reporter system integrated as a single-copy lysogen to avoid titrating NtrC or polymerase. A wide variety of bending geometries was found to support a similar level of transcriptional activation ( approximately 3-4-fold). Computer modeling of the DNA trajectories suggests that the most inactive promoters have short spacer DNA and the NtrC sites on the opposite side of the helix as the wild-type sites; otherwise, the loop can form effectively. Flexibility and multivalency of the NtrC-Esigma(54) interaction apparently provides substantial independence from DNA stiffness constraints, and in general activation requires less efficient looping than repression. However, none of the random templates were as active as wild-type promoter. Subsidiary activator binding sites in the wild-type were found to be required for full activity, but, surprisingly, these sites could not be functionally replaced by strong binding sites. This suggests that one or more protomers in the NtrC octamer must form and then release contacts with DNA in order to complete the ATPase cycle and act as an AAA(+) activator of the Esigma(54). This dynamic DNA wrapping around the NtrC octamer is proposed to be necessary for efficient activation, and the wrapping may also reduce adventitious activation of other promoters.
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PMID:Geometric and dynamic requirements for DNA looping, wrapping and unwrapping in the activation of E.coli glnAp2 transcription by NtrC. 1532 47

A 73-year-old man with a history of hypertension and drug-induced hepatitis underwent surgical treatment of an enlarging pararenal abdominal aortic aneurysm (PRAAA) with bilateral renal artery stenosis, found on enhanced computed tomography (CT). His preoperative renal function was normal. We divided the right renal artery and used a 6-mm expanded polytetrafluoroethylene (ePTFE) tube graft for the anastomosis. Renal artery perfusion was achieved by a rapid infusion pump set at 200 ml/min. The left renal artery was reconstructed and perfused in the same way. The abdominal aorta was cross-clamped just distal to the superior mesenteric artery and a Y-graft was anastomosed. The ePTFE grafts were connected to the Y-graft and bilateral renal artery circulation was re-established. The renal ischemic time was 1 h 25 min and the urine output during reconstruction was 80 ml. Postoperatively, his serum blood urea nitrogen and serum creatinine levels increased slightly, but normalized within 3 days. This case report shows that this method of renal artery perfusion could prove useful for complex renal artery reconstructions.
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PMID:Repair of a pararenal abdominal aortic aneurysm with bilateral renal artery stenosis using a rapid infusion pump for renal perfusion: report of a case. 1866 22

Rhizobium leguminosarum bv. viciae forms nitrogen-fixing nodules on several legumes, including pea (Pisum sativum) and vetch (Vicia cracca), and has been widely used as a model to study nodule biochemistry. To understand the complex biochemical and developmental changes undergone by R. leguminosarum bv. viciae during bacteroid development, microarray experiments were first performed with cultured bacteria grown on a variety of carbon substrates (glucose, pyruvate, succinate, inositol, acetate, and acetoacetate) and then compared to bacteroids. Bacteroid metabolism is essentially that of dicarboxylate-grown cells (i.e., induction of dicarboxylate transport, gluconeogenesis and alanine synthesis, and repression of sugar utilization). The decarboxylating arm of the tricarboxylic acid cycle is highly induced, as is gamma-aminobutyrate metabolism, particularly in bacteroids from early (7-day) nodules. To investigate bacteroid development, gene expression in bacteroids was analyzed at 7, 15, and 21 days postinoculation of peas. This revealed that bacterial rRNA isolated from pea, but not vetch, is extensively processed in mature bacteroids. In early development (7 days), there were large changes in the expression of regulators, exported and cell surface molecules, multidrug exporters, and heat and cold shock proteins. fix genes were induced early but continued to increase in mature bacteroids, while nif genes were induced strongly in older bacteroids. Mutation of 37 genes that were strongly upregulated in mature bacteroids revealed that none were essential for nitrogen fixation. However, screening of 3,072 mini-Tn5 mutants on peas revealed previously uncharacterized genes essential for nitrogen fixation. These encoded a potential magnesium transporter, an AAA domain protein, and proteins involved in cytochrome synthesis.
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PMID:Transcriptomic analysis of Rhizobium leguminosarum biovar viciae in symbiosis with host plants Pisum sativum and Vicia cracca. 1937 75

In this work, a morpho-histological study of banana (Musa spp. cv. Grande Naine [AAA]) embryogenic cell suspensions during cryopreservation and regeneration was performed. It was demonstrated that the regeneration process of somatic embryos originating from cryopreserved cell suspensions was different from that of control cell suspensions. Somatic embryos originating from cryopreserved cell suspensions had a unicellular origin. The regeneration process was modified not only by freezing in liquid nitrogen but also by the plasmolyzing effect of the 0.5 M sucrose solution employed during pretreatment. This result explained the high number of embryonic structures formed on M3 medium, compared with the control. Proembryos blocked at the globular stage could pursue their development when they were plated on new culture medium at a lower density after 30 days of culture on M3 medium. The unicellular origin of somatic embryos produced from cryopreserved cell suspensions offers the prospect of using cryopreservation to select non-chimeral transformed plants.
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PMID:Morpho-histological study of banana (Musa spp. cv. Grande Naine [AAA]) cell suspensions during cryopreservation and regeneration. 2030 95

This study explored if a combined supplementation of GH and IGF-1 had an additive effect on whole body nitrogen economy, energy, substrate and skeletal muscle metabolism following surgical trauma. Patients were randomized to controls (C; n = 10), to GH (0.15 IU/kg/injection) (GH; n = 7) or GH combined with IGF-1 (40 mug/kg/injection) subcutaneously twice a day (GH-IGF-1; n = 9) together with standardized parenteral nutrition. Muscle amino acids, glutathione and the ribosomal pattern reflecting protein synthesis, and nitrogen balance were measured. GH- and GH-IGF-1 groups showed lower urea and higher plasma glucose concentrations. Energy expenditure increased in the GH-group. GH-IGF-1 prevented a decrease in muscle polyribosomes indicating a preserved muscle protein synthesis. In the GH group unaltered BCAA and AAA levels were seen in muscle indicating an unchanged protein breakdown, while the other groups showed increased muscle concentrations postoperatively. Without statistically difference GH marginally improved the nitrogen balance, in terms of higher values, and growth factors improved the nitrogen balance when the shift in urea was taken into account. To conclude, growth factors influences urea metabolism, protein degradation and protein synthesis. There was no clearcut additional effect when combining GH and IGF-1 but the study was probably underpowered to outrule this and effects on nitrogen balance.
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PMID:Effects of growth hormone and insulin-like growth factor-1 on postoperative muscle and substrate metabolism. 2079 57

The yellow-green alga Trachydiscus minutus (Eustigmatophyceae, Heterocontophyta) was cultivated in a standard medium and under nitrogen- and phosphorus-starvation and its triacylglycerols were analyzed by RP-HPLC/MS-APCI. The molecular species of triacylglycerols included a total of 74 triacylglycerols having at least one polyunsaturated fatty acid. Polyunsaturated triacylglycerols were identified for the first time in a yellow-green alga. N-starvation brought about a nearly 50% drop in TAGs containing EPA, and also decreased TAGs containing ARA, while P-starvation had a sizable effect on those TAGs that contain two or three arachidonic acids. In four TAGs containing PUFA, i.e. EEE, EEA, EAA and AAA, N-starvation caused a rapid fivefold increase in ARA content and the ratio of TAGs containing ARA, i.e. AEE to AAA increased tenfold relative to control. Regioisomeric characterization of triacylglycerols containing palmitic, arachidonic (ARA) and eicosapentaenoic acids (EPA) showed that the proportion of positional isomers is affected by N- and P-starvation. N- and P-starvation also changed the ratio of symmetrical to asymmetrical TAGs. Positional isomers exhibited identical ratios of symmetrical and asymmetrical TAGs irrespective of the type of FAs. In control cultivation the major TAGs with a single PUFA were symmetrical ones (PEP or PAP) whose ratio to asymmetrical counterparts (PPE or PPA) was about 3:1, whereas N- and P-starvation yielded opposite ratios, 1:3-1:5. The control cultivation yielded ~90% asymmetrical TAGs with two PUFAs (i.e. PEE and PAA), whereas with N- and P-starvation the ratio of symmetrical to asymmetrical TAGs increased to 2:1 and 3:2, respectively.
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PMID:Effect of nitrogen and phosphorus starvation on the polyunsaturated triacylglycerol composition, including positional isomer distribution, in the alga Trachydiscus minutus. 2191 Dec 35

FeaR is an AraC family regulator that activates transcription of the tynA and feaB genes in Escherichia coli. TynA is a periplasmic topaquinone- and copper-containing amine oxidase, and FeaB is a cytosolic NAD-linked aldehyde dehydrogenase. Phenylethylamine, tyramine, and dopamine are oxidized by TynA to the corresponding aldehydes, releasing one equivalent of H2O2 and NH3. The aldehydes can be oxidized to carboxylic acids by FeaB, and (in the case of phenylacetate) can be further degraded to enter central metabolism. Thus, phenylethylamine can be used as a carbon and nitrogen source, while tyramine and dopamine can be used only as sources of nitrogen. Using genetic, biochemical and computational approaches, we show that the FeaR binding site is a TGNCA-N8-AAA motif that occurs in 2 copies in the tynA and feaB promoters. We show that the coactivator for FeaR is the product rather than the substrate of the TynA reaction. The feaR gene is upregulated by carbon or nitrogen limitation, which we propose reflects regulation of feaR by the cyclic AMP receptor protein (CRP) and the nitrogen assimilation control protein (NAC), respectively. In carbon-limited cells grown in the presence of a TynA substrate, tynA and feaB are induced, whereas in nitrogen-limited cells, only the tynA promoter is induced. We propose that tynA and feaB expression is finely tuned to provide the FeaB activity that is required for carbon source utilization and the TynA activity required for nitrogen and carbon source utilization.
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PMID:Finely tuned regulation of the aromatic amine degradation pathway in Escherichia coli. 2401 33

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