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181.
182.
Dufresne A Ostrowski M Scanlan DJ Garczarek L Mazard S Palenik BP Paulsen IT de Marsac NT Wincker P Dossat C Ferriera S Johnson J Post AF Hess WR Partensky F 《Genome biology》2008,9(5):R90-16
Background
The picocyanobacterial genus Synechococcus occurs over wide oceanic expanses, having colonized most available niches in the photic zone. Large scale distribution patterns of the different Synechococcus clades (based on 16S rRNA gene markers) suggest the occurrence of two major lifestyles ('opportunists'/'specialists'), corresponding to two distinct broad habitats ('coastal'/'open ocean'). Yet, the genetic basis of niche partitioning is still poorly understood in this ecologically important group.Results
Here, we compare the genomes of 11 marine Synechococcus isolates, representing 10 distinct lineages. Phylogenies inferred from the core genome allowed us to refine the taxonomic relationships between clades by revealing a clear dichotomy within the main subcluster, reminiscent of the two aforementioned lifestyles. Genome size is strongly correlated with the cumulative lengths of hypervariable regions (or 'islands'). One of these, encompassing most genes encoding the light-harvesting phycobilisome rod complexes, is involved in adaptation to changes in light quality and has clearly been transferred between members of different Synechococcus lineages. Furthermore, we observed that two strains (RS9917 and WH5701) that have similar pigmentation and physiology have an unusually high number of genes in common, given their phylogenetic distance.Conclusion
We propose that while members of a given marine Synechococcus lineage may have the same broad geographical distribution, local niche occupancy is facilitated by lateral gene transfers, a process in which genomic islands play a key role as a repository for transferred genes. Our work also highlights the need for developing picocyanobacterial systematics based on genome-derived parameters combined with ecological and physiological data. 相似文献183.
184.
Jeltsje S. Cnossen Rachel K. Morris Gerben ter Riet Ben W.J. Mol Joris A.M. van der Post Arri Coomarasamy Aeilko H. Zwinderman Stephen C. Robson Patrick J.E. Bindels Jos Kleijnen Khalid S. Khan 《CMAJ》2008,178(6):701-711
Background
Alterations in waveforms in the uterine artery are associated with the development of pre-eclampsia and intrauterine growth restriction. We investigated the predictive accuracy of all uterine artery Doppler indices for both conditions in the first and second trimesters.Methods
We identified relevant studies through searches of MEDLINE, EMBASE, the Cochrane Library and Medion databases (all records to April 2006) and by checking bibliographies of identified studies and consulting with experts. Four of us independently selected studies, extracted data and assessed study validity. We performed a bivariable meta-analysis of sensitivity and specificity and calculated likelihood ratios.Results
We identified 74 studies of pre-eclampsia (total 79 547 patients) and 61 studies of intrauterine growth restriction (total 41 131 patients). Uterine artery Doppler ultrasonography provided a more accurate prediction when performed in the second trimester than in the first-trimester. Most Doppler indices had poor predictive characteristics, but this varied with patient risk and outcome severity. An increased pulsatility index with notching was the best predictor of pre-eclampsia (positive likelihood ratio 21.0 among high-risk patients and 7.5 among low-risk patients). It was also the best predictor of overall (positive likelihood ratio 9.1) and severe (positive likelihood ratio 14.6) intrauterine growth restriction among low-risk patients.Interpretation
Abnormal uterine artery waveforms are a better predictor of pre-eclampsia than of intrauterine growth restriction. A pulsatility index, alone or combined with notching, is the most predictive Doppler index. These indices should be used in clinical practice. Future research should also concentrate on combining uterine artery Doppler ultrasonography with other tests.Pre-eclampsia and intrauterine growth restriction remain important causes of maternal and perinatal morbidity and mortality.1–3 Maternal complications of pre-eclampsia include coagulopathy, renal and liver failure, and stroke.1 Adults who were affected by intrauterine growth restriction in utero are at increased risk for cardiovascular disease, hypertension and type 2 diabetes.4,5Pre-eclampsia and intrauterine growth restriction are characterized by abnormal placenta formation,6 which results in inadequate uteroplacental blood flow. This has led to the idea of using Doppler ultrasonography to assess the velocity of uterine artery blood flow as part of routine ultrasound screening.7 Low end-diastolic velocities and an early diastolic notch characterize the waveforms of uterine artery blood flow in women who are not pregnant or are in their first trimester. Persistence of a diastolic notch (beyond 24 weeks'' gestation) or abnormal flow velocity ratios have been associated with inadequate trophoblast invasion.8Accurate prediction of pre-eclampsia and intrauterine growth restriction is crucial to allow judicious allocation of resources for monitoring and preventive treatment to improve maternal and perinatal outcomes.9,10 However, studies investigating the predictive accuracy of uterine artery Doppler indices (Box 1) have revealed considerably varied results. Thus, it is questionable whether uterine artery Doppler ultrasonography should be used as a predictive test. We undertook this review to investigate the accuracy of all uterine artery Doppler indices in predicting pre-eclampsia and intrauterine growth restriction.Open in a separate windowBox 1 相似文献185.
Kancheva R Sulková S Svára F Hill M Kanchev L Zofková I 《Physiological research / Academia Scientiarum Bohemoslovaca》2008,57(Z1):S181-S185
In hemodialyzed patients hormonal disturbances are known to occur. However, melatonin levels have not been completely studied. The aim of the study was to find whether changes in calcaemia affect melatonin secretion. For this reason we followed the nocturnal serum concentrations of melatonin and parathyroid hormone (PTH) in 9 hemodialyzed patients (6 women and 3 men, aged 37-65 years) both before and 1-3 months after parathyroidectomy at 6 p.m., 9 p.m., 11 p.m., 2 a.m., 5 a.m. and 7 a.m. At 6 p.m. blood samples to evaluate the levels of calcium and phosphate were also collected. Parathyroidectomy resulted in an increase in nocturnal melatonin levels. As expected, the parathyroidectomy was followed by considerable PTH decrease. PTH showed no nocturnal variation before or after parathyroidectomy. Calcium levels significantly decreased after the operation while phosphate levels increased. In summary, in hemodialyzed patients with hyperparathyroidism, parathyroidectomy significantly increases the nocturnal secretion of melatonin. Relationships between the pineal gland and parathyroid glands have yet to be elucidated. 相似文献
186.
D. J. Scanlan M. Ostrowski S. Mazard A. Dufresne L. Garczarek W. R. Hess A. F. Post M. Hagemann I. Paulsen F. Partensky 《Microbiology and molecular biology reviews》2009,73(2):249-299
Summary: Marine picocyanobacteria of the genera Prochlorococcus and Synechococcus numerically dominate the picophytoplankton of the world ocean, making a key contribution to global primary production. Prochlorococcus was isolated around 20 years ago and is probably the most abundant photosynthetic organism on Earth. The genus comprises specific ecotypes which are phylogenetically distinct and differ markedly in their photophysiology, allowing growth over a broad range of light and nutrient conditions within the 45°N to 40°S latitudinal belt that they occupy. Synechococcus and Prochlorococcus are closely related, together forming a discrete picophytoplankton clade, but are distinguishable by their possession of dissimilar light-harvesting apparatuses and differences in cell size and elemental composition. Synechococcus strains have a ubiquitous oceanic distribution compared to that of Prochlorococcus strains and are characterized by phylogenetically discrete lineages with a wide range of pigmentation. In this review, we put our current knowledge of marine picocyanobacterial genomics into an environmental context and present previously unpublished genomic information arising from extensive genomic comparisons in order to provide insights into the adaptations of these marine microbes to their environment and how they are reflected at the genomic level. 相似文献
187.
Jon T Giles Moyses Szklo Wendy Post Michelle Petri Roger S Blumenthal Gordon Lam Allan C Gelber Robert Detrano William W Scott Jr Richard A Kronmal Joan M Bathon 《Arthritis research & therapy》2009,11(2):R36
Introduction
Although cardiovascular morbidity and mortality are increased in rheumatoid arthritis, little is known about the burden of subclinical coronary atherosclerosis in these patients.Methods
Using computed tomography, coronary artery calcification was measured in 195 men and women with rheumatoid arthritis aged 45 to 84 years without clinical cardiovascular disease and compared with 1,073 controls without rheumatoid arthritis enrolled in the Baltimore cohort of the Multi-Ethnic Study of Atherosclerosis.Results
The prevalence of coronary calcification (Agatston score > 0) was significantly higher in men, but not women, with rheumatoid arthritis after adjusting for sociodemographic and cardiovascular risk factors (prevalence ratio = 1.19; P = 0.012). Among participants with prevalent calcification, those with rheumatoid arthritis had adjusted mean Agatston scores 53 units higher than controls (P = 0.002); a difference greater for men than women (P for interaction = 0.017). In all analyses, serum IL-6 attenuated the association between rheumatoid arthritis and coronary calcification, suggesting its role as a potential mediator of enhanced atherosclerosis. Notably, increasing severity of rheumatoid arthritis was associated with a higher prevalence and extent of coronary calcification among both men and women with rheumatoid arthritis, and for all age categories. The largest percentage difference in coronary arterial calcification between rheumatoid arthritis patients and their nonrheumatoid arthritis counterparts was observed in the youngest age category.Conclusions
Increasing rheumatoid arthritis disease severity was associated with a higher prevalence and greater extent of coronary artery calcification, potentially mediated through an atherogenic effect of chronic systemic inflammation. Gender and age differences in association with coronary calcification suggest that preventive measures should be emphasized in men with rheumatoid arthritis, and considered even in younger rheumatoid arthritis patients with low levels of traditional cardiovascular risk factors. 相似文献188.
Understanding the population-level impacts of climate change is critical for effectively managing ecosystems. Predators are
important components of many systems because they provide top−down control of community structure. Ecological theory suggests
that these species could be particularly susceptible to climate change because they generally occur at low densities and have
resource-limited populations. Yet, our understanding of climate-change impacts on predators is hindered by the difficulty
in assessing complex, nonlinear dynamics over the large spatial scales necessary to depict a species’ general response to
abiotic forcing. Here we use fur-return data to characterize population dynamics of a snow-adapted carnivore, the wolverine,
across most of its North American range. Using novel modeling techniques, we simultaneously measured the impact of winter
snowpack on wolverine dynamics across critical thresholds in snowpack depth and two domains of population growth. Winter snowpack
declined from 1970 to 2004 in nearly the entire region studied, concordant with increases in Northern Hemisphere temperature
anomalies. Fur returns have declined in many areas; our models show that snowpack has strong, nonlinear effects on wolverine
population dynamics. Importantly, wolverine harvests dropped the fastest in areas where snowpack declined most rapidly and
also where snowpack had the greatest effect on population dynamics. Moreover, declining snow cover appears to drive trends
in wolverine population synchrony, with important implications for overall persistence. These results illustrate the vulnerability
and complex responses of predator populations to climate change. We also suggest that declining snowpack may be an important
and hitherto little-analyzed mechanism through which climate change alters high-latitude ecosystems. 相似文献
189.
Latha Satish Sandra Johnson Adam Abdulally J. Christopher Post Garth D. Ehrlich Sandeep Kathju 《Cell stress & chaperones》2010,15(6):819-826
We have previously identified the CCT subunit eta as specifically reduced in healing fetal skin wounds by differential display,
and observed that this reduction is not seen with any other CCT subunit. We now report the cloning and characterization of
the cDNAs for rabbit CCT-eta and its closest evolutionary homolog, CCT-beta. Quantitative examination of CCT-eta and –beta
message expression in healing fetal and adult wounds at 12 h post-injury confirms that CCT-eta mRNA is decreased in fetal
wound tissues, but actually elevated in adult wound tissues. CCT-beta mRNA, in contrast, remains unchanged in both fetal and
adult wound tissues. CCT-eta mRNA remains persistently elevated in healing adult wounds for 28 days following injury, whereas
CCT-beta mRNA remains invariant throughout. CCT-eta protein is similarly increased, whereas CCT-beta protein remains unchanged.
-smooth muscle actin (-SMA), a recognized substrate of CCT known to be important in integumentary wound healing, was also measured over the course
of wound healing, and both mRNA and protein levels were elevated throughout the 28 days. 相似文献
190.
Anna Svárovská Thomas H. Ant Veronika Seblová Lucie Jecná Stephen M. Beverley Petr Volf 《PLoS neglected tropical diseases》2010,4(1)