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161.
Petretta M Spinelli L Marciano F Apicella C Vicario ML Testa G Volpe M Bonaduce D 《American journal of physiology. Heart and circulatory physiology》2000,279(1):H86-H92
This study evaluated the effect of angiotensin II receptor blockade on cardiac autonomic control adaptation and urine output in response to acute isotonic volume load in patients with idiopathic dilated cardiomyopathy (DCM) and asymptomatic to mildly symptomatic heart failure. Left ventricular volumes and heart rate variability measurements were assessed at baseline and during intravenous saline load in 14 patients before and after 2 mo of losartan treatment. After losartan treatment, blood pressure values were lower, whereas left ventricular ejection fraction was higher (F = 79, P < 0.001), than before treatment. During saline load, ejection fraction decreased before losartan treatment (F = 5.6, P < 0.05) but did not change after treatment. Urinary volume, unchanged during saline load in untreated patients, increased after losartan (F = 9.38, P < 0. 001). Time-domain measurements that represent vagal modulation of heart rate (root-mean-square successive differences and percentage of differences between successive R-R intervals >50 ms) decreased during saline load in untreated patients (F = 3.1, P < 0.05 and F = 6.5, P < 0.01, respectively), but not after losartan. Similarly, a decrease in very low frequency (F = 3.2, P < 0.05), low-frequency (F = 2.9, P < 0.05), and high-frequency power (F = 6.1, P < 0.01) after saline load was observed only in untreated patients. In patients with DCM, losartan treatment improves the cardiac autonomic adaptation and increases urine output in response to volume overload. 相似文献
162.
163.
The glycoprotein calsequestrin (CS) is segregated to the junctional sarcoplasmic reticulum (jSR) and is responsible for intraluminal Ca(2+) binding. A chimeric CS-hemoagglutinin 1 (HA1), obtained by adding the nine amino acid viral epitope hemoagglutinin to the carboxy terminal of CS and shown to be correctly segregated to skeletal muscle jSR [A. Nori, K. A. Nadalini, A. Martini, R. Rizzuto, A. Villa, and P. Volpe (1997). Chimeric calsequestrin and its targeting to the junctional sarcoplasmic reticulum of skeletal muscle. Am. J. Physiol. 272, C1420-C1428] lends itself as a molecular tool to investigate the targeting domains of CS. A putative targeting mechanism of CS to jSR implies glycosylation-dependent steps in the endoplasmic reticulum (ER) and Golgi complex. To test this hypothesis, CS-HA1DeltaGly, a mutant in which the unique N-glycosylation site Asn316 was changed to Ile, was engineered by site-directed mutagenesis. The mutant cDNA was transiently transfected in either HeLa cells, myoblasts of rat skeletal muscle primary cultures, or regenerating soleus muscle fibers of adult rats. The expression and intracellular localization of CS-HA1DeltaGly was studied by double-labeling epifluorescence by means of antibodies against either CS, HA1, or the ryanodine receptor calcium release channel. CS-HA1DeltaGly was expressed and retained to ER and ER/sarcoplasmic reticulum of HeLa cells and myotubes, respectively, and expressed, sorted, and correctly segregated to jSR of regenerating soleus muscle fibers. Thus, the targeting mechanism of CS in vivo appears not to be affected by glycosylation-that is, the sorting, docking, and segregation of CS are independent of cotranslational and posttranslational glycosylation or glycosylations. 相似文献
164.
Bakker BM Overkamp KM van Maris AJ Kötter P Luttik MA van Dijken JP Pronk JT 《FEMS microbiology reviews》2001,25(1):15-37
In Saccharomyces cerevisiae, reduction of NAD(+) to NADH occurs in dissimilatory as well as in assimilatory reactions. This review discusses mechanisms for reoxidation of NADH in this yeast, with special emphasis on the metabolic compartmentation that occurs as a consequence of the impermeability of the mitochondrial inner membrane for NADH and NAD(+). At least five mechanisms of NADH reoxidation exist in S. cerevisiae. These are: (1) alcoholic fermentation; (2) glycerol production; (3) respiration of cytosolic NADH via external mitochondrial NADH dehydrogenases; (4) respiration of cytosolic NADH via the glycerol-3-phosphate shuttle; and (5) oxidation of intramitochondrial NADH via a mitochondrial 'internal' NADH dehydrogenase. Furthermore, in vivo evidence indicates that NADH redox equivalents can be shuttled across the mitochondrial inner membrane by an ethanol-acetaldehyde shuttle. Several other redox-shuttle mechanisms might occur in S. cerevisiae, including a malate-oxaloacetate shuttle, a malate-aspartate shuttle and a malate-pyruvate shuttle. Although key enzymes and transporters for these shuttles are present, there is as yet no consistent evidence for their in vivo activity. Activity of several other shuttles, including the malate-citrate and fatty acid shuttles, can be ruled out based on the absence of key enzymes or transporters. Quantitative physiological analysis of defined mutants has been important in identifying several parallel pathways for reoxidation of cytosolic and intramitochondrial NADH. The major challenge that lies ahead is to elucidate the physiological function of parallel pathways for NADH oxidation in wild-type cells, both under steady-state and transient-state conditions. This requires the development of techniques for accurate measurement of intracellular metabolite concentrations in separate metabolic compartments. 相似文献
165.
G. Di Marco A. Gismondi L. Canuti M. Scimeca A. Volpe A. Canini 《Plant biology (Stuttgart, Germany)》2014,16(4):792-800
Environmental antibiotic contamination is due mainly to improper and illegal disposal of these molecules that, yet pharmacologically active, are excreted by humans and animals. These compounds contaminate soil, water and plants. Many studies have reported the bioaccumulation of antibiotics in plants and their negative effects on photosynthesis, cell growth and oxidative balance. Therefore, the principal objective of this paper was the study of antibiotic accumulation sites in plants and its uptake modality. Iberis sempervirens L., grown in soil and in agar in the presence or absence of tetracycline, were used as a model system. Using confocal and transmission electron microscopy, we demonstrated that tetracycline was absorbed and propagated in plants through apoplastic transport and also accumulated in intercellular spaces. Tetracycline was rarely detected inside cells (in cytoplasm and mitochondria where, coherent to its pharmacological activity, it probably affected ribosomes), except in stomata. Moreover, we verified and clarified further the phytotoxic effects of tetracycline on plants. We observed that the antibiotic induced a large reduction in plant growth and development and inhibition of photosynthetic activity. As tetracycline may lead to oxidative stress in plants, plant cells tried to balance this disequilibrium by increasing the amount and activity of some endogenous enzyme antioxidant agents (superoxide dismutase 1 and catalase) and levels of antiradical secondary metabolites. 相似文献
166.
In infants less than 3 years old pulmonary hyperinflation can be a clinical and radiological sign of acute pneumonitis. It is an early, nonspecific occurrence in the presence of inflammation. The most reliable radiologic signs include flattening and undulation of the diaphragm, mediastinal elongation and narrowing, and a cardiac outline completely visualized above the diaphragm. 相似文献
167.
168.
Silvia?Rossi Caterina?Motta Valeria?Studer Giulia?Macchiarulo Elisabetta?Volpe Francesca?Barbieri Gabriella?Ruocco Fabio?Buttari Annamaria?Finardi Raffaele?Mancino Sagit?Weiss Luca?Battistini Gianvito?Martino Roberto?Furlan Jelena?Drulovic Diego?CentonzeEmail author 《Molecular neurodegeneration》2014,9(1):56
169.
José Mauro Granjeiro Carmen Verissima Ferreira Paulo Afonso Granjeiro Cinthia Celestino Da Silva Eulázio Mikio Taga Pedro Luiz Onofre Volpe 《Journal of enzyme inhibition and medicinal chemistry》2013,28(5):345-350
Uric acid inhibited 50% of the activity of bovine kidney low molecular mass phosphotyrosine protein phosphatase at concentrations of 1.0, 0.4, 1.3, and 0.2 mM, respectively for p -nitrophenyl phosphate (p -NPP), flavine mononucleotide, β -naphthyl phosphate and tyrosine phosphate (Tyr-P) as substrates. The mixed type inhibition of p -NPP hydrolysis was fully reversible, with K ic and K iu values of 0.4 and 1.1 mM, respectively; the inhibition by uric acid shifted the pH optimum from 5.0 to 6.5. When Tyr-P was the substrate, competitive inhibition was observed with a K i value of 0.05 mM. Inhibition studies by uric acid in the presence of thiol compounds, and preincubation studies in the presence of inorganic phosphate suggest that the interaction of uric acid with the enzyme occurred at the active site, but did not involve SH residues, and that the mechanism of inhibition depended on the structure of the substrates. 相似文献
170.
Body mass explains characteristic scales of habitat selection in terrestrial mammals 总被引:1,自引:0,他引:1
Niche theory in its various forms is based on those environmental factors that permit species persistence, but less work has focused on defining the extent, or size, of a species' environment: the area that explains a species' presence at a point in space. We proposed that this habitat extent is identifiable from a characteristic scale of habitat selection, the spatial scale at which habitat best explains species' occurrence. We hypothesized that this scale is predicted by body size. We tested this hypothesis on 12 sympatric terrestrial mammal species in the Canadian Rocky Mountains. For each species, habitat models varied across the 20 spatial scales tested. For six species, we found a characteristic scale; this scale was explained by species' body mass in a quadratic relationship. Habitat measured at large scales best-predicted habitat selection in both large and small species, and small scales predict habitat extent in medium-sized species. The relationship between body size and habitat selection scale implies evolutionary adaptation to landscape heterogeneity as the driver of scale-dependent habitat selection. 相似文献