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11.
Effect of 17days of bed rest on peak isometric force and unloaded shortening velocity of human soleus fibers 总被引:6,自引:0,他引:6
Widrick J. J.; Romatowski J. G.; Bain J. L.W.; Trappe S. W.; Trappe T. A.; Thompson J. L.; Costill D. L.; Riley D. A.; Fitts R. H. 《American journal of physiology. Cell physiology》1997,273(5):C1690
The purpose of this study was to examine the effect of prolongedbed rest (BR) on the peak isometric force(Po) and unloaded shorteningvelocity (Vo)of single Ca2+-activated musclefibers. Soleus muscle biopsies were obtained from eight adult malesbefore and after 17 days of 6° head-down BR. Chemicallypermeabilized single fiber segments were mounted between a forcetransducer and position motor, activated with saturating levels ofCa2+, and subjected to slacklength steps. Vowas determined by plotting the time for force redevelopment vs. theslack step distance. Gel electrophoresis revealed that 96% of the pre-and 87% of the post-BR fibers studied expressed only the slow type Imyosin heavy chain isoform. Fibers with diameter >100 µm made uponly 14% of this post-BR type I population compared with 33% of thepre-BR type I population. Consequently, the post-BR type I fibers(n = 147) were, on average, 5%smaller in diameter than the pre-BR type I fibers(n = 218) and produced 13% lessabsolute Po. BR had no overalleffect on Po per fibercross-sectional area(Po/CSA), even though halfof the subjects displayed a decline of 9-12% inPo/CSA after BR. Type Ifiber Voincreased by an average of 34% with BR. Although the ratio of myosinlight chain 3 to myosin light chain 2 also rose with BR, there was nocorrelation between this ratio andVo for either thepre- or post-BR fibers. In separate fibers obtained from the originalbiopsies, quantitative electron microscopy revealed a 20-24%decrease in thin filament density, with no change in thick filamentdensity. These results raise the possibility that alterations in thegeometric relationships between thin and thick filaments may be atleast partially responsible for the elevatedVo of the post-BRtype I fibers. 相似文献
12.
A Emami-Khoyi DA Hartley RH Cruickshank LJ Boren JG Ross 《New Zealand journal of zoology.》2016,43(4):322-335
New Zealand fur seals are one of many pinniped species that survived the commercial sealing of the eighteenth and nineteenth centuries in dangerously low numbers. After the enforcement of a series of protection measures in the early twentieth century, New Zealand fur seals began to recover from the brink of extinction. We examined the New Zealand fur seal populations of Banks Peninsula, South Island, New Zealand using the mitochondrial DNA control region. We identified a panmictic population structure around Banks Peninsula. The most abundant haplotype in the area showed a slight significant aggregated structure. The Horseshoe Bay colony showed the least number of shared haplotypes with other colonies, suggesting a different origin of re-colonisation of this specific colony. The effective population size of the New Zealand fur seal population at Banks Peninsula was estimated at approximately 2500 individuals. The exponential population growth rate parameter for the area was 35, which corresponds to an expanding population. In general, samples from adjacent colonies shared 4.4 haplotypes while samples collected from colonies separated by between five and eight bays shared 1.9 haplotypes. The genetic data support the spill-over dynamics of colony expansion already suggested for this species. Approximate Bayesian computations analysis suggests re-colonisation of the area from two main clades identified across New Zealand with a most likely admixture coefficient of 0.41 to form the Banks Peninsula population. Approximate Bayesian computations analysis estimated a founder population size of approximately 372 breeding individuals for the area, which then rapidly increased in size with successive waves of external recruitment. The population of fur seals in the area is probably in the late phase of maturity in the colony expansion dynamic. 相似文献
13.
Purification and characterization of Dolichos lablab lectin 总被引:1,自引:0,他引:1
The mannose/glucose-binding Dolichos lablab lectin (designated DLL) has
been purified from seeds of Dolichos lablab (hyacinth bean) to
electrophoretic homogeneity by affinity chromatography on an ovalbumin-
Sepharose 4B column. The purified lectin gave a single symmetric protein
peak with an apparent molecular mass of 67 kDa on gel filtration
chromatography, and five bands ranging from 10 kDa to 22 kDa upon SDS-PAGE.
N-Terminal sequence analysis of these bands revealed subunit heterogeneity
due to posttranslational proteolytic truncation at different sites mostly
at the carboxyl terminus. The carbohydrate binding properties of the
purified lectin were investigated by three different approaches:
hemagglutination inhibition assay, quantitative precipitation inhibition
assay, and ELISA. On the basis of these studies, it is concluded that the
Dolichos lablab lectin has neither an extended carbohydrate combining site,
nor a hydrophobic binding site adjacent to it. The carbohydrate combining
site of DLL appears to most effectively accommodate a nonreducing terminal
alpha-d-mannosyl unit, and to be complementary to the C-3, C-4, and C-6
equatorial hydroxyl groups of alpha-d-mannopyranosyl and
alpha-d-glucopyranosyl residues. DLL strongly precipitates murine IgM but
not IgG, and the recent finding that this lectin interacts specifically
with NIH 3T3 fibroblasts transfected with the Flt3 tyrosine kinase receptor
and preserves human cord blood stem cells and progenitors in a quiescent
state for prolonged periods in culture, make this lectin a valuable tool in
biomedical research.
相似文献
14.
15.
Pascale Simard Hugo Galarneau Sébastien Marois Daniel Rusu Caroline D Hoemann Patrice E Poubelle Hani El-Gabalawy Maria JG Fernandes 《Arthritis research & therapy》2009,11(3):R74-10
Introduction
Osteoarthritis is characterized by the progressive destruction of cartilage in the articular joints. Novel therapies that promote resurfacing of exposed bone in focal areas are of interest in osteoarthritis because they may delay the progression of this disabling disease in patients who develop focal lesions. Recently, the addition of 80% deacetylated chitosan to cartilage microfractures was shown to promote the regeneration of hyaline cartilage. The molecular mechanisms by which chitosan promotes cartilage regeneration remain unknown. Because neutrophils are transiently recruited to the microfracture site, the effect of 80% deacetylated chitosan on the function of neutrophils was investigated. Most studies on neutrophils use preparations of chitosan with an uncertain degree of deacetylation. For therapeutic purposes, it is of interest to determine whether the degree of deacetylation influences the response of neutrophils to chitosan. The effect of 95% deacetylated chitosan on the function of neutrophils was therefore also investigated and compared with that of 80% deacetylated chitosan. 相似文献16.
Cecilia JG de Almeida Jean-Fran?ois Jasmin Francesco Del Galdo Michael P Lisanti 《Cell cycle (Georgetown, Tex.)》2013,12(14):2248-2254
Caveolar domains act as platforms for the organization of molecular complexes involved in signal transduction. Caveolin proteins, the principal structural components of caveolae, have been involved in many cellular processes. Caveolin-1 (Cav-1) and caveolin-2 (Cav-2) are highly expressed in the lung. Cav-1-deficient mice (Cav-1−/−) and Cav-2-deficient mice (Cav-2−/−) exhibit severe lung dysfunction attributed to a lack of Cav-2 expression. Recently, Cav-1 has been shown to regulate lung fibrosis in different models. Here, we show that Cav-2 is also involved in modulation of the fibrotic response, but through distinct mechanisms. Treatment of wild-type mice with the pulmonary fibrosis-inducer bleomycin reduced the expression of Cav-2 and its phosphorylation at tyrosine 19. Importantly, Cav-2−/− mice, but not Cav-1−/− mice, were more sensitive to bleomycin-induced lung injury in comparison to wild-type mice. Bleomycin-induced lung injury was characterized by alveolar thickening, increase in cell density, and extracellular matrix deposition. The lung injury observed in bleomycin-treated Cav-2−/− mice was not associated with alterations in the TGF-β signaling pathway and/or in the ability to produce collagen. However, apoptosis and proliferation were more prominent in lungs of bleomycin-treated Cav-2−/− mice. Since Cav-1−/− mice also lack Cav-2 expression and show a different outcome after bleomycin treatment, we conclude that Cav-1 and Cav-2 have distinct roles in bleomycin induced-lung fibrosis, and that the balance of both proteins determines the development of the fibrotic process. 相似文献
17.
Two distinct conformational states define the interaction of human RAD51‐ATP with single‐stranded DNA 下载免费PDF全文
Andrea Candelli Edwige B Garcin Mauro Modesti Luca Pellegrini Gijs JL Wuite Erwin JG Peterman 《The EMBO journal》2018,37(7)
An essential mechanism for repairing DNA double‐strand breaks is homologous recombination (HR). One of its core catalysts is human RAD51 (hRAD51), which assembles as a helical nucleoprotein filament on single‐stranded DNA, promoting DNA‐strand exchange. Here, we study the interaction of hRAD51 with single‐stranded DNA using a single‐molecule approach. We show that ATP‐bound hRAD51 filaments can exist in two different states with different contour lengths and with a free‐energy difference of ~4 kBT per hRAD51 monomer. Upon ATP hydrolysis, the filaments convert into a disassembly‐competent ADP‐bound configuration. In agreement with the single‐molecule analysis, we demonstrate the presence of two distinct protomer interfaces in the crystal structure of a hRAD51‐ATP filament, providing a structural basis for the two conformational states of the filament. Together, our findings provide evidence that hRAD51‐ATP filaments can exist in two interconvertible conformational states, which might be functionally relevant for DNA homology recognition and strand exchange. 相似文献
18.
The alcohol dehydrogenase (Adh) region from five planitibia subgroup
species of Hawaiian picture-wing Drosophila has been cloned. A total of 15
kb of DNA in and around the Adh gene has been compared among the five
species. Genetic distances were calculated to determine evolutionary
relationships. These distances agree with previous distances determined by
protein polymorphism and DNA hybridization techniques and can be
interpreted in terms of specific island colonization and speciation
(founder) events over the past 5 Myr. Examination of the restriction maps
of the cloned Adh region from the five species shows many instances of
small deletions, insertion of a transposable element in D. heteroneura, and
the existence of a highly variable region on the 3' side of the Adh gene.
Clustering relationships and rates of DNA change are calculated and
compared with the relationship found for other species of Drosophila.
相似文献
19.
Arjan D van Zuilen Ingeborgh van der Tweel Peter J Blankestijn Michiel L Bots Marjolijn van Buren Marc AGJ ten Dam Karin AH Kaasjager Peter JG van de Ven Gerald Vervoort Louis-Jean Vleming Gerry Ligtenberg Jack FM Wetzels 《Trials》2006,7(1):1-9
Background
Patients with chronic kidney disease (CKD) are at a greatly increased risk of developing cardiovascular disease. Recently developed guidelines address multiple risk factors and life-style interventions. However, in current practice few patients reach their targets. A multifactorial approach with the aid of nurse practitioners was effective in achieving treatment goals and reducing vascular events in patients with diabetes mellitus and in patients with heart failure. We propose that this also holds for the CKD population.Design
MASTERPLAN is a multicenter randomized controlled clinical trial designed to evaluate whether a multifactorial approach with the aid of nurse-practicioners reduces cardiovascular risk in patients with CKD. Approximately 800 patients with a creatinine clearance (estimated by Cockcroft-Gault) between 20 to 70 ml/min, will be included. To all patients the same set of guidelines will be applied and specific cardioprotective medication will be prescribed. In the intervention group the nurse practitioner will provide lifestyle advice and actively address treatment goals. Follow-up will be five years. Primary endpoint is the composite of myocardial infarction, stroke and cardiovascular mortality. Secondary endpoints are cardiovascular morbidity, overall mortality, decline of renal function, change in markers of vascular damage and change in quality of life. Enrollment has started in April 2004 and the study is on track with 700 patients included on October 15th, 2005. This article describes the design of the MASTERPLAN study. 相似文献20.
Peters RJ Bonnier HJ Bredee JJ 《International journal of cardiovascular interventions》1999,2(3):153-162
In 1996 the Minister of Public Health, Welfare and Sports in The Netherlands published a 'Planning Decree Special Interventions in the Heart'. She requested from the professional organizations guidelines for the indications for interventions in the heart. A working group was formed with representatives from the Dutch professional organizations for cardiology and thoracic surgery, to address this issue for patients with coronary artery disease. The working group confirmed the need to discuss all patients who are considered for either elective or emergency revascularization during a multidisciplinary consultation in (or with) one of the specialized Dutch hospitals. During this meeting of the 'heart team', at least one interventional cardiologist and one thoracic surgeon should be present. There are three possible outcomes of the heart team's consultations for each patient: drug therapy only ('conservative management'), coronary surgery or catheter intervention. For each case, the team should indicate the expected benefit, the risk of the intervention, the urgency and the estimated waiting time. The guidelines presented in this paper address these issues for three patient categories: stable angina pectoris, unstable angina pectoris and acute myocardial infarction. 相似文献