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131.
Marković BB Bergovec M Reiner Z Sertić J Vincelj J Marković M 《Collegium antropologicum》2007,31(1):179-183
Controversy exists as to whether the deletion/deletion (DD) genotype of angiotensin l-converting enzyme (ACE) gene polymorphism is associated with coronary heart disease (CHD). There are only a few studies dealing with this issue in the elderly, also with controversial results. The aim of this study was the assessment of correlation between genetic markers and the risk of CHD in the elderly. The results indicated DD genotype importance for CHD in the elderly as proven by discriminant analysis (chi2 = 25.77; df = 16; p = 0.0620). However, the use of univariate method demonstrated no correlation between DD genotype of ACE gene polymorphism and coronary artery disease. D allele of ACE gene was associated with higher activities of ACE plasma. A weak, but increased risk of MI is associated with high frequency of DD genotype in the elderly. Strong correlation between ACE polymorphism and ACE plasma activities was demonstrated. 相似文献
132.
Bergman MR Teerlink JR Mahimkar R Li L Zhu BQ Nguyen A Dahi S Karliner JS Lovett DH 《American journal of physiology. Heart and circulatory physiology》2007,292(4):H1847-H1860
Although enhanced cardiac matrix metalloproteinase (MMP)-2 synthesis has been associated with ventricular remodeling and failure, whether MMP-2 expression is a direct mediator of this process is unknown. We generated transgenic mice expressing active MMP-2 driven by the alpha-myosin heavy chain promoter. At 4 mo MMP-2 transgenic hearts demonstrated expression of the MMP-2 transgene, myocyte hypertrophy, breakdown of Z-band registration, lysis of myofilaments, disruption of sarcomere and mitochondrial architecture, and cardiac fibroblast proliferation. Hearts from 8-mo-old transgenic mice displayed extensive myocyte disorganization and dropout with replacement fibrosis and perivascular fibrosis. Older transgenic mice also exhibited a massive increase in cardiac MMP-2 expression, representing recruitment of endogenous MMP-2 synthesis, with associated expression of MMP-9 and membrane type 1 MMP. Increases in diastolic [control (C) 33 +/- 3 vs. MMP 51 +/- 12 microl; P = 0.003] and systolic (C 7 +/- 2 vs. MMP 28 +/- 14 microl; P = 0.003) left ventricular (LV) volumes and relatively preserved stroke volume (C 26 +/- 4 vs. MMP 23 +/- 3 microl; P = 0.16) resulted in markedly decreased LV ejection fraction (C 78 +/- 7% vs. MMP 48 +/- 16%; P = 0.0006). Markedly impaired systolic function in the MMP transgenic mice was demonstrated in the reduced preload-adjusted maximal power (C 240 +/- 84 vs. MMP 78 +/- 49 mW/microl(2); P = 0.0003) and decreased end-systolic pressure-volume relation (C 7.5 +/- 1.5 vs. MMP 4.7 +/- 2.0; P = 0.016). Expression of active MMP-2 is sufficient to induce severe ventricular remodeling and systolic dysfunction in the absence of superimposed injury. 相似文献
133.
Neutrophil extracellular traps (NETs) are considered to be part of the human innate immunity because they trap and kill pathogens. NETs are formed by activated neutrophils and consist of a DNA backbone with embedded antimicrobial peptides and enzymes. They are involved in host defense during pneumococcal pneumonia, streptococcal necrotizing fasciitis, appendicitis and insemination. Recently, bacterial virulence factors that counteract NETs have been identified. These include the degradation of the NET-backbone by DNases enabling the liberation of bacteria from NETs, as well as capsule formation, which reduces bacterial trapping. Furthermore, pathogens can resist NET-mediated killing by adding positive charge to their cell surface. 相似文献
134.
Albiger B Dahlberg S Sandgren A Wartha F Beiter K Katsuragi H Akira S Normark S Henriques-Normark B 《Cellular microbiology》2007,9(3):633-644
Toll-like receptor 9 (TLR9) induces an inflammatory response by recognition of unmethylated CpG dinucleotides, mainly present in prokaryotic DNA. So far, TLR9-deficient mice have been shown to be more sensitive than wild-type mice to viral, but not to bacterial infections. Here, we show that mice deficient in TLR9 but not in TLR1, TLR2, TLR4 and TLR6 or IL-1R/IL-18R are more susceptible to a respiratory tract bacterial infection caused by Streptococcus pneumoniae. Intranasal challenge studies revealed that TLR9 plays a protective role in the lungs at an early stage of infection prior to the entry of circulating inflammatory cells. Alveolar as well as bone marrow-derived macrophages deficient in either TLR9 or the myeloid adaptor differentiation protein MyD88 were impaired in pneumococcal uptake and in pneumococcal killing. Our data suggest that in the airways, pneumococcal infection triggers a TLR9 and MyD88-dependent activation of phagocytic activity from resident macrophages leading to an early clearance of bacteria from the lower respiratory tract. 相似文献
135.
New statistical modelling methods, such as neural networks (NNs), allow us to take a step further in the understanding of
complex relations in aquatic ecosystems. In this paper the results from the analysis of macro-invertebrate communities in
a complex riverine environment are presented. We attempted to explain observed changes in species composition and abundance
with neural network modelling methods and compared the results to linear regression. The NN method used is an improved form
of the RF5 algorithm, developed to effectively discover numeric laws from data. RF5 uses Product Unit Networks (PUNs), which
are in effect multivariate non-discrete power functions. The data set consisted of a 10-year time series of monthly samples
of macro-invertebrates on artificial substrates in the rivers Rhine and Meuse in the Netherlands. During this period the invertebrate
community has largely changed coinciding with the␣invasion of Ponto-Caspian crustaceans. We used physical–chemical data and
data on the abundance of the invasive taxa Corophium curvispinum and Dikerogammarus villosis to explain the observed changes in the resident invertebrate community. The analyses showed temperature, abundance of invasive
taxa and peak discharges as important factors. Comparison of the results from NN modelling to linear regression revealed that
the factors temperature and abundance of Dikerogammarus
villosis explained equally well in both cases. Only the neural network was able to use information on peak discharge and timing of
the peak in the previous winter to improve model performances. Neural networks are known to yield excellent modelling results,
a drawback however is their lack of transparency or their ‘black box’ character. The use of relatively easy interpretable
(white box) PUNs allows us to investigate the extracted relations in more detail and can enhance our understanding of ecosystem
functioning. Our results show that peak discharges might be an important factor structuring invertebrate communities in rivers
and hint on the existence of interacting effects from invasive species and discharge peaks. They finally show the value of
biological data sets that are collected over a long period and in a highly standardised way. 相似文献
136.
Forest P. Hayes Joshua J. Millspaugh Eric J. Bergman Ragan M. Callaway Chad J. Bishop 《The Journal of wildlife management》2022,86(2):e22175
Across much of North America, populations of moose (Alces alces) are declining because of disease, predation, climate change, and anthropogenic-driven habitat loss. Contrary to this trend, populations of moose in Colorado, USA, have continued to grow. Studying successful (i.e., persistent or growing) populations of moose can facilitate continued conservation by identifying habitat features critical to persistence of moose. We hypothesized that moose using habitat with higher quality willow (Salix spp.) would have a higher probability of having a calf-at-heel (i.e., calving success). We evaluated moose calving success using repeated ground observations of collared individuals with calves in an occupancy model framework to account for detection probability. We then evaluated the impact of willow habitat quality and nutrition on moose calving success by studying 2 spatially segregated populations of moose in Colorado. Last, we evaluated correlations between willow characteristics (browse intensity, height, cover, leaf length, and species) and willow nutrition (dry matter digestibility [DMD]) to assess the utility of using those characteristics to assess willow nutrition. We found willow height and cover had a high probability of being positively associated with higher individual-level calving success. Willow DMD, browse intensity, and leaf length were not predictive of individual moose calving success; however, the site with higher mean DMD consistently had higher mean estimates of calving success for the same year. Our results suggest surveying DMD is likely not a useful metric for assessing differences in calving success of individual moose but may be of use at population levels. Further, the assessment of willow morphology and density may be used to identify areas that support higher levels of moose calving success. 相似文献
137.
Sandra Muschiol Murat Balaban Staffan Normark Birgitta Henriques‐Normark 《BioEssays : news and reviews in molecular, cellular and developmental biology》2015,37(4):426-435
Transport of DNA across bacterial membranes involves complex DNA uptake systems. In Gram‐positive bacteria, the DNA uptake machinery shares fundamental similarities with type IV pili and type II secretion systems. Although dedicated pilus structures, such as type IV pili in Gram‐negative bacteria, are necessary for efficient DNA uptake, the role of similar structures in Gram‐positive bacteria is just beginning to emerge. Recently two essentially very different pilus structures composed of the same major pilin protein ComGC were proposed to be involved in transformation of the Gram‐positive bacterium Streptococcus pneumoniae – one is a long, thin, type IV pilus‐like fiber with DNA binding capacity and the other one is a pilus structure that was thicker, much shorter and not able to bind DNA. Here we discuss how competence induced pili, either by pilus retraction or by a transient pilus‐related opening in the cell wall, may mediate DNA uptake in S. pneumoniae. 相似文献
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