bluuebunny/crossref_metadata_2025 huggingface dataset:
Aneuploidy in Human Spermatozoa
Authors: Templado C. , Vidal F. , Estop A.
Published: March 2011

We reviewed the frequency and distribution of disomy in spermatozoa obtained by multicolor-FISH analysis on decondensed sperm nuclei in (a) healthy men, (b) fathers of aneuploid offspring of paternal origin and (c) individuals with Klinefelter syndrome and XYY males. In series of healthy men, disomy per autosome is approximately 0.1% but may range from 0.03 (chromosome 8) to 0.47 (chromosome 22). The great majority of authors find that chromosome 21 (0.18%) and the sex chromosomes (0.27%) have significantly elevated frequencies of disomy although these findings are not universal. The total disomy in FISH studies is 2.26% and the estimated aneuploidy (2× disomy) is 4.5%, more than double that seen in sperm karyotypes (1.8%). Increased disomy levels of low orders of magnitude have been reported in spermatozoa of some normal men (stable variants) and in men who have fathered children with Down, Turner and Klinefelter syndromes. These findings suggest that men with a moderately elevated aneuploidy rate may be at a higher risk of fathering paternally derived aneuploid pregnancies. Among lifestyle factors, smoking, alcohol and caffeine have been studied extensively but the compounding effects of the 3 are difficult to separate because they are common lifestyle behaviors. Increases in sex chromosome abnormalities, some autosomal disomies, and in the number of diploid spermatozoa are general features in 47,XXY and 47,XYY males. Aneuploidy of the sex chromosomes is more frequent than aneuploidy of any of the autosomes not only in normal control individuals, but also in patients with sex chromosome abnormalities and fathers of paternally derived Klinefelter, Turner and Down syndromes.
Prevention and Correction Mechanisms behind Anaphase Synchrony: Implications for the Genesis of Aneuploidy
Authors: Matos I. , Maiato H.
Published: March 2011

The perpetuation of the species’ genomic identity strongly depends on the accurate maintenance of chromosome number through countless cell generations. The synchronous entry and progression of all chromosomes through anaphase is fundamental for the quality of mitosis and is guaranteed by error prevention and correction mechanisms that ultimately certify the bipolar attachment of chromosomes to the mitotic spindle, the uniform distribution of forces amongst different chromosomes, and the simultaneity of sister-chromatid separation. The existence of a kinetochore-attachment checkpoint (KAC; also known as spindle-assembly checkpoint) ensures a delay in anaphase onset if any kinetochore remains unattached or devoid of a proper complement of microtubules. The stochastic nature of microtubule-kinetochore interactions predisposes the mitotic process to mistakes, but different molecular players cooperate by detecting and releasing incorrect attachments and thus delaying checkpoint satisfaction. Conversely, correct microtubule-kinetochore interactions become selectively stabilized. Once anaphase onset is triggered, the segregation velocities achieved by each chromosome should be similar, so that none of the chromosomes is lagged behind. This reflects the uniformity of forces acting on the different chromosomes and relies on a conspicuous mitotic spindle property known as microtubule poleward flux. Importantly, not all incorrect attachments are detected and resolved prior to anaphase leading to asynchronous chromosome segregation, but several mechanisms are in place to prevent aneuploidy. One of these mechanisms relies on anaphase spindle forces and another, known as the NoCut checkpoint, delays cell cleavage during cytokinesis until chromosomes can free the spindle mid-region. In this review we discuss how these different mechanisms act in concert to ensure the fidelity of the mitotic process.
Aneuploidy and DNA Fragmentation in Sperm of Carriers of a Constitutional Chromosomal Abnormality
Authors: Perrin A. , Basinko A. , Douet-Guilbert N. , Gueganic N. , Le Bris M.-J. , Amice V. , De Braekeleer M. , Morel F.
Published: March 2011

Among various causes responsible for infertility, it has been admitted for a long time that male infertility can be due to impaired spermatogenesis and/or balanced structural chromosomal abnormalities. Sperm DNA fragmentation is also considered as another cause of infertility. Most of the studies on male infertility have concerned either aneuploidy in the sperm of carriers of constitutional chromosomal abnormalities or sperm DNA fragmentation. This review is aimed at analyzing these 2 parameters in the same patients. Furthermore, we present work on the study of these 2 parameters in the same gametes of 4 carriers of a balanced chromosomal abnormality. Meiotic segregation was analyzed by fluorescent in situ hybridization and DNA fragmentation was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. It was shown that aneuploidy and DNA fragmentation were increased in the sperm of carriers of a balanced chromosomal abnormality. For all 4 carriers of a balanced structural abnormality, there was a 2–5 times higher proportion of spermatozoa with unbalanced chromosomal content and fragmented DNA than among those with normal/balanced content. Moreover, we found a non-random distribution with more gametes with DNA fragmentation when these arose from a particular segregation mode. The mechanism which would tend to explain our results is abortive apoptosis. In conclusion, both meiotic segregation and DNA fragmentation studies should be integrated in the genetic exploration of male carriers of a chromosomal structural abnormality.
Mosaic Aneuploidy in Early Fetal Losses
Authors: Lebedev I.
Published: March 2011

Chromosomal mosaicism is the presence of 2 or more cell lines with different karyotypes in the same individual. Mosaic karyotypes are a remarkable feature of early stages of human embryo development. They result from mitotic errors in chromosome segregation and demonstrate the clearest example of somatic mutagenesis in human beings. This review is devoted to the classification of chromosomal mosaicism and the analysis of its underlying mechanisms, incidence and phenotypic effects during embryo development. A model for tissue-specific aneuploid cell line compartmentalization in spontaneous abortions is introduced.
Predisposition to Aneuploidy in the Oocyte
Authors: Vialard F. , Boitrelle F. , Molina-Gomes D. , Selva J.
Published: March 2011

While the incidence of predisposition to aneuploidy in the oocyte increases with age, there is also evidence of increased incidence in young women with recurrent miscarriage, recurrent aneuploidy, or recurrent implantation failure after in vitro fertilization. There is evidence from mouse models and from observations in humans that follicle-stimulating hormone (FSH) probably has a direct or indirect effect on the occurrence of oocyte aneuploidy. It seems that increased endogenous or exogenous FSH could induce meiotic disruption. Although the effect of FSH may explain the age-related increase in aneuploidy rate, many questions remain regarding young women, even if their FSH level is sometimes increased. Disruption of meiotic gene expression caused by exposure to environmental contaminants or by gene defects could also predispose to oocyte aneuploidy. Such abnormalities could impact on the oocyte pool, recombination and synapsis during fetal life, or oocyte growth.
The Human Cleavage Stage Embryo Is a Cradle of Chromosomal Rearrangements
Authors: Voet T. , Vanneste E. , Vermeesch J.R.
Published: March 2011

The first cell cycles following in vitro fertilization (IVF) of human gametes are prone to chromosome instability. Many, but often not all, blastomeres of an embryo acquire a genetic makeup during cleavage that is not representative of the original zygotic genome. Whole chromosomes are missegregated, but also structural rearrangements of chromosomes do occur in human cleavage stage embryogenesis following IVF. Analysis of pre- and postnatal DNA samples indicates that the in vivo human conceptions also endure instability of chromosome number and structure during cleavage of the fertilized oocyte. This embryonic chromosome instability not necessarily undermines normal human development, but may lead to a spectrum of conditions, including loss of conception, genetic disease and genetic variation development. In this review, the structural instability of chromosomes during human cleavage stage embryogenesis is catalogued, channeled into etiologic models and linked to genomic profiles of healthy and diseased newborns.
Influence of Treatment with Inhalable Heroin on Pulmonary Function
Authors: Buster M.C.A. , van den Brink W. , van Brussel G.H.A. , van Ree J.M.
Published: March 2011

This study aims to asses the influence of inhalable heroin on pulmonary function in chronic heroin-dependent patients treated with inhalable heroin. Among 32 patients (all cigarette smokers), a spirometric test was conducted at baseline and after an average period of 10 months of treatment with medically prescribed heroin. Patients showed a high frequency of pulmonary dysfunction at baseline [34%, with percentage of forced expiratory volume in 1 s (%FEV1) <80%]. However, after excluding those who started pulmonary treatment (n = 2) or who used heroin intravenously only (n = 2), no statistically significant differences in %FEV1 between baseline and follow-up were observed (n = 28; mean %FEV1 86% at baseline vs. 91% at follow-up; p = 0.09). This small and relatively brief study suggests that 10 months of co-prescribed inhalable heroine base does not seem to (further) deteriorate pulmonary function in chronic, cigarette smoking treatment refractory heroin addicts. Screening for and treatment of pulmonary dysfunction is recommended for methadone patients with and without co-prescribed heroin.
Evolution of Patchily Distributed Proteins Shared between Eukaryotes and Prokaryotes: Dictyostelium as a Case Study
Authors: Andersson Jan O.
Published: March 2011

Protein families are often patchily distributed in the tree of life; they are present in distantly related organisms, but absent in more closely related lineages. This could either be the result of lateral gene transfer between ancestors of organisms that encode them, or losses in the lineages that lack them. Here a novel approach is developed to study the evolution of patchily distributed proteins shared between prokaryotes and eukaryotes. Proteins encoded in the genome of cellular slime mold Dictyostelium discoideum and a restricted number of other lineages, including at least one prokaryote, were identified. Analyses of the phylogenetic distribution of 49 such patchily distributed protein families showed conflicts with organismal phylogenies; 25 are shared with the distantly related amoeboflagellate Naegleria (Excavata), whereas only two are present in the more closely related Entamoeba. Most protein families show unexpected topologies in phylogenetic analyses; eukaryotes are polyphyletic in 85% of the trees. These observations suggest that gene transfers have been an important mechanism for the distribution of patchily distributed proteins across all domains of life. Further studies of this exchangeable gene fraction are needed for a better understanding of the origin and evolution of eukaryotic genes and the diversification process of eukaryotes.
Enhancement of Thermostable Lipase Production by a Genotypically Identified Extremophilic Bacillus subtilis NS 8 in a Continuous Bioreactor
Authors: Olusesan Akanbi Taiwo , Azura L. Kamaruzaman , Abubakar Fatimah , Mohamed Abdul Karim Sabo , Radu Son , Manap Mohd Yazid Abdul , Saari Nazamid
Published: March 2011

Bacillus strain NS 8, a lipase-producing bacterium isolated from a Malaysian hot spring, is able to tolerate a broad range of temperature and pH, which makes it beneficial for this study. It generated PCR products with molecular weight of 1,532 bp, and the 16S rRNA sequence analysis identified it as Bacillus subtilis with accession number AB110598. It showed a 71% similarity index with B. subtilis using Biolog Microstation System. Its lipase production was optimized using a shake flask system by changing the physical (agitation speed, pH and temperature) and nutritional (nitrogen, carbon and minerals) factors. The most suitable combination of the basal medium for lipase production was 2.5% olive oil (carbon), 1.5% peptone (nitrogen), 0.1% MgSO4 (mineral) at an optimum temperature of 50°C, pH 7.5 and 150 rpm agitation, giving an enzyme yield of 4.23 U/ml. Statistical optimization using response surface methodology was carried out. An optimum lipase production of 5.67 U/ml was achieved when olive oil concentration of 3%, peptone 2%, MgSO4·7H2O 0.2% and an agitation rate of 200 rpm were combined. Lipase production was further carried out inside a 2-liter bioreactor, which yielded an enzyme activity of 14.5 U/ml after 15 h of incubation.
Physiological Importance of Cytochrome c Peroxidase in Ethanologenic Thermotolerant Zymomonas mobilis
Authors: Charoensuk Kannikar , Irie Akira , Lertwattanasakul Noppon , Sootsuwan Kaewta , Thanonkeo Pornthap , Yamada Mamoru
Published: March 2011

Zymomonas mobilis ZmCytC as a peroxidase bearing three heme c-binding motifs was investigated with ΔZmcytC constructed. The mutant exhibited filamentous shapes and reduction in growth under a shaking condition at a high temperature compared to the parental strain and became hypersensitive to exogenous H2O2. Under the same condition, the mutation caused increased expression of genes for three other antioxidant enzymes. Peroxidase activity, which was detected in membrane fractions with ubiquinol-1 as a substrate but not with reduced horse heart cytochrome c, was almost abolished in ΔZmcytC. Peroxidase activity was also detected with NADH as a substrate, which was significantly inhibited by antimycin A. NADH oxidase activity of ΔZmcytC was found to be about 80% of that of the parental strain. The results suggest the involvement of ZmCytC in the aerobic respiratory chain via the cytochrome bc1 complex in addition to the previously proposed direct interaction with ubiquinol and its contribution to protection against oxidative stress.
Population Incidence of Guillain-Barré Syndrome: A Systematic Review and Meta-Analysis
Authors: Sejvar James J. , Baughman Andrew L. , Wise Matthew , Morgan Oliver W.
Published: March 2011

Population incidence of Guillain-Barré syndrome (GBS) is required to assess changes in GBS epidemiology, but published estimates of GBS incidence vary greatly depending on case ascertainment, definitions, and sample size. We performed a meta-analysis of articles on GBS incidence by searching Medline (1966–2009), Embase (1988–2009), Cinahl (1981–2009) and CABI (1973–2009) as well as article bibliographies. We included studies from North America and Europe with at least 20 cases, and used population-based data, subject matter experts to confirm GBS diagnosis, and an accepted GBS case definition. With these data, we fitted a random-effects negative binomial regression model to estimate age-specific GBS incidence. Of 1,683 nonduplicate citations, 16 met the inclusion criteria, which produced 1,643 cases and 152.7 million person-years of follow-up. GBS incidence increased by 20% for every 10-year increase in age; the risk of GBS was higher for males than females. The regression equation for calculating the average GBS rate per 100,000 person-years as a function of age in years was exp[–12.0771 + 0.01813(age in years)] × 100,000. Our findings provide a robust estimate of background GBS incidence in Western countries. Our regression model may be used in comparable populations to estimate the background age-specific rate of GBS incidence for future studies.
Effects of Subcortical Vascular Ischemic Dementia and Aging on Negative and Neutral Word List Learning
Authors: Billino Jutta , Luerssen Jan , von Renteln-Kruse Wolfgang , Mühlhan Christine , Rösler Alexander
Published: March 2011

Background: Subcortical ischemic vascular dementia (SIVD) represents an important subgroup of vascular dementia. Besides characteristic cognitive deficits, particular emotional problems support the diagnosis. Emotional disturbances in SIVD are not well understood. Method: We studied the performance of SIVD patients, healthy young control persons and old control persons in an emotional word list learning task. Results: SIVD patients showed lower memory performance than both control groups for neutral as well as for negative words. However, we found a significant emotional memory advantage for negative words in all 3 diagnostic groups. Conclusion: SIVD patients are able to profit from emotional information in order to enhance their memory performance.
Human Tissue Kallikrein Promoted Activation of the Ipsilesional Sensorimotor Cortex after Acute Cerebral Infarction
Authors: Wang Yi-Dong , Lu Rui-Yan , Huang Xiao-Xiong , Yuan Fang , Hu Tao , Peng Ying , Huang Sui-Qiao
Published: March 2011

Background/Aims: Kallikrein, a serine proteinase, has been reported to have many functions, such as selectively dilating arterioles in the ischemic area and enhancing angiogenesis and neurogenesis. Therefore, it may promote cerebral poststroke reorganization. We observed the effect of human tissue kallikrein on the brain motor activation of acute ischemic stroke patients and evaluated patient condition severity and prognosis. Methods: Forty-four cases suffering from cerebral infarction between 6 and 72 h of onset were randomly assigned into the kallikrein group (n = 24) and the control group (n = 20). The control group was given conventional treatment, whereas the kallikrein group was given both conventional treatment and human tissue kallikrein over the course of 12–14 days. The activation of the sensorimotor cortex (SMC) and cerebellum, the affected forefinger strength and the NIHSS scores were evaluated before and after treatment. The MBI and MRS scores were assessed at 30 and 90 days after stroke onset. Results: There were no differences between the two groups in activation volume, patient condition and scores before treatment. After treatment, the ipsilesional SMC activation volume was significantly larger and the increase in the volume was significantly greater in the kallikrein group than in the control group (p < 0.05 for both). The NIHSS score was significantly smaller and the improvement in the score was significantly greater in the kallikrein group after treatment (p < 0.05 for both). Moreover, the MBI scores at 30 days were significantly higher, whereas the MRS scores at 30 days were significantly lower in the kallikrein group than in the control group (p < 0.05 for both). Conclusions: Kallikrein improved neural function effectively and quickly after stroke, and promoting cerebral reorganization might be an important mechanism for kallikrein in the treatment of acute cerebral infarction.
Association Between High-Sensitivity C-Reactive Protein and Coronary Plaque Subtypes Assessed by 64-Slice Coronary Computed Tomography Angiography in an Asymptomatic Population
Authors: Rubin Jonathan , Chang Hyuk-Jae , Nasir Khurram , Blumenthal Roger S. , Blaha Michael J. , Choi Eue-Keun , Chang Sung-A. , Yoon Yeonyee E. , Chun Eun Ju , Choi Sang-il , Agatston Arthur S. , Rivera Juan J.
Published: March 2011

Background—

Elevated levels of C-reactive protein (CRP) are associated with poor cardiovascular outcomes, even after accounting for traditional cardiovascular risk factors. We sought to analyze the relationship between levels of CRP and coronary plaque subtypes as assessed by coronary computed tomography angiography.

Methods and Results—

We evaluated 1004 asymptomatic South Korean subjects (mean age, 49±9.3 years) who underwent coronary computed tomography angiography as part of a health screening evaluation. We examined the association between increasing CRP levels and plaque subtypes using multivariable linear and logistic regression analysis. Coronary plaque was observed in 211 of 1004 individuals (21%). Subjects with high CRP (≥2 mg/L) had an increased prevalence of any plaque type (30.7% versus 16.7%
P
<0.001) and mixed calcified arterial plaque (MCAP) (19.3% versus 6.3%
P
<0.001) as compared with subjects with low-normal CRP. Multivariable logistic regression analysis demonstrated that elevated CRP predicted the presence of any MCAP (high versus low-normal CRP group; odds ratio, 2.81; 95% confidence interval, 1.62 to 4.89). When examining the multivariable logistic regression analysis between the presence of ≥2 plaques and CRP, subjects with high CRP were more likely to have MCAP than those with low-normal CRP levels (odds ratio, 3.78; 95% confidence interval, 1.49 to 9.55).

Conclusions

Elevated levels of CRP are associated with an increased prevalence of MCAP as assessed by coronary computed tomography angiography. Longitudinal studies will determine if the excess risk observed in persons with elevated CRP may be mediated, at least in part, by an increased burden of MCAP.
Noninvasive Assessment of Atherosclerotic Plaque Progression in ApoE
−/−
Mice Using Susceptibility Gradient Mapping
Authors: Makowski Marcus R. , Varma Gopal , Wiethoff Andrea J. , Smith Alberto , Mattock Katherine , Jansen Christian H.P. , Warley Alice , Taupitz Matthias , Schaeffter Tobias , Botnar Rene M.
Published: March 2011

Background—

Macrophages have been identified as a major contributor to plaque development and destabilization in atherosclerosis. The aim of this study was to noninvasively assess uptake of citrate coated very small iron oxide particles at different stages of plaque development in the brachiocephalic artery of apoE
−/−
mice. Susceptibility gradient mapping (SGM) was applied to generate positive contrast images and to quantify iron oxide uptake.

Methods and Results—

ApoE
−/−
mice were fed a high-fat diet for 4, 8, or 12 weeks; 300 μmol Fe/kg was injected 24 and 48 hours before final MRI. Increasing very small iron oxide particle uptake was observed over the course of atherosclerotic plaque development. Simultaneous administration of pravastatin led to a significant decrease in very small iron oxide particle uptake, assessed by mass spectroscopy and histology. SGM-MRI allowed the generation of positive contrast images, and magnitudes (mT/m) of contrast enhancement in SG parameter maps significantly correlated with the absolute iron oxide content (
R
2
=0.70,
P
<0.05) and the macrophage density (
R
2
=0.71,
P
<0.05).

Conclusions—

This study shows an increase in iron oxide uptake (measured by in vivo SGM-MRI, histology, and mass spectroscopy) with the progression of plaque development in an apoE
−/−
mouse model of accelerated atherosclerosis. Positive contrast provided by SGM-MRI allowed for a clear visualization of intraplaque iron oxide depositions, and magnitudes (mT/m) of contrast enhancement in SG parameter maps allowed for the quantification of intraplaque iron oxide particles.
Cardiac Troponin T Measured by a Highly Sensitive Assay Predicts Coronary Heart Disease, Heart Failure, and Mortality in the Atherosclerosis Risk in Communities Study
Authors: Saunders Justin T. , Nambi Vijay , de Lemos James A. , Chambless Lloyd E. , Virani Salim S. , Boerwinkle Eric , Hoogeveen Ron C. , Liu Xiaoxi , Astor Brad C. , Mosley Thomas H. , Folsom Aaron R. , Heiss Gerardo , Coresh Josef , Ballantyne Christie M.
Published: March 2011

Background—

We evaluated whether cardiac troponin T (cTnT) measured with a new highly sensitive assay was associated with incident coronary heart disease (CHD), mortality, and hospitalization for heart failure (HF) in a general population of participants in the Atherosclerosis Risk in Communities (ARIC) Study.

Methods and Results—

Associations between increasing cTnT levels and CHD, mortality, and HF hospitalization were evaluated with Cox proportional hazards models adjusted for traditional CHD risk factors, kidney function, high-sensitivity C-reactive protein, and N-terminal pro–B-type natriuretic peptide in 9698 participants aged 54 to 74 years who at baseline were free from CHD and stroke (and HF in the HF analysis). Measurable cTnT levels (≥0.003 μg/L) were detected in 66.5% of individuals. In fully adjusted models, compared with participants with undetectable levels, those with cTnT levels in the highest category (≥0.014 μg/L; 7.4% of the ARIC population) had significantly increased risk for CHD (hazard ratio=2.29; 95% confidence interval, 1.81 to 2.89), fatal CHD (hazard ratio=7.59; 95% confidence interval, 3.78 to 15.25), total mortality (hazard ratio=3.96; 95% confidence interval, 3.21 to 4.88), and HF (hazard ratio=5.95; 95% confidence interval, 4.47 to 7.92). Even minimally elevated cTnT (≥0.003 μg/L) was associated with increased risk for mortality and HF (
P
<0.05). Adding cTnT to traditional risk factors improved risk prediction parameters; the improvements were similar to those with N-terminal pro–B-type natriuretic peptide and better than those with the addition of high-sensitivity C-reactive protein.

Conclusions—

cTnT detectable with a highly sensitive assay was associated with incident CHD, mortality, and HF in individuals from a general population without known CHD/stroke.
Percutaneous Vascular Stent Implantation as Treatment for Central Vascular Obstruction Due to Fibrosing Mediastinitis
Authors: Albers Erin L. , Pugh Meredith E. , Hill Kevin D. , Wang Li , Loyd James E. , Doyle Thomas P.
Published: March 2011

Background—

Fibrosing Mediastinitis (FM) is a rare complication of infection with
Histoplasma capsulatum
that can lead to obstruction of pulmonary and systemic vasculature and large airways, often resulting in significant morbidity and mortality. Medical therapy is ineffective, and surgical intervention is often not feasible. Stent implantation offers a potential treatment for vascular obstruction due to FM, but this has not been well studied.

Methods and Results—

We conducted a retrospective review of all patients undergoing cardiac catheterization for FM. Anatomic site of stenosis and hemodynamic information before and after intervention, as well as clinical presentation and follow-up data, were recorded. From 1996 to 2008, 58 patients underwent cardiac catheterization for FM, with intervention performed in 40 (69%). A total of 77 stents were used to relieve 59 lesions (pulmonary artery=26, pulmonary vein=21, and superior vena cava=12). Significant reduction in pressure gradients (
P
<0.001) and increase in vessel caliber (
P
<0.001) were seen at all locations. Symptomatic recurrent stenosis requiring further intervention occurred in 11 patients (28%). Median time to recurrence was 115 months. Thirty-two (87%) of 37 patients for whom follow-up was available reported symptomatic improvement after stent placement. Procedure-related complications occurred in 14 patients (24%). Overall mortality was 19%, with the majority of deaths in patients with bilateral disease. Among patients with bilateral disease, intervention was associated with improved survival at 5 years.

Conclusion—

Percutaneous vascular stent implantation is an effective therapy for central vascular obstruction due to FM, providing significant relief of anatomic obstruction and sustained clinical improvement.
Pathological Healing Response of Explanted MitraClip Devices
Authors: Ladich Elena , Michaels Mary Beth , Jones Russell M. , McDermott Elizabeth , Coleman Leslie , Komtebedde Jan , Glower Donald , Argenziano Michael , Feldman Ted , Nakano Masataka , Virmani Renu
Published: March 2011

Background—

The safety and effectiveness of the MitraClip device (Abbott Vascular, Menlo Park, CA) is being evaluated in the Endovascular Valve Edge-to-Edge Repair Study (EVEREST) clinical studies. The healing response after device implantation has not previously been characterized in humans.

Methods and Results—

A total of 67 explanted devices (implantation duration, 1 to 1878 days) from 50 patients were submitted for histological evaluation. Explants were analyzed in 4 implantation intervals: acute (≤30 days; n=7), subacute (31 to 90 days; n=23), chronic (91 to 300 days; n=18), and long term (>300 days; n=19). The acute healing response consisted of platelet/fibrin deposition. The subacute response exhibited granulation tissue with early fibrous encapsulation (pannus). The chronic response was characterized by various degrees of tissue bridging between the device arms. The long-term healing response demonstrated collagen-rich matrix (by type I collagen), incorporating the device components with complete encapsulation by organized, fibrous growth. In long-term devices with minimal surgical disruption, a fibrous tissue bridge (mean area, 7.39±4.3 mm
2
) was observed over and between the device arms, resulting in atrial tissue continuity between the 2 valve leaflets. Devices demonstrated no evidence of endocarditis, mechanical wear, component fracture, or corrosion up to the time of explantation (median, 119 days; first and third quartiles, 42 and 365 days).

Conclusions—

In all patients, device mechanical integrity was maintained up to the time of explantation. Four phases of physiological healing were observed: platelet and fibrin deposition, inflammation, granulation tissue, and finally, fibrous encapsulation. Long-term device fibrous encapsulation with extension over adjacent mitral leaflets and tissue bridge formation adds structural stability.

Clinical Trial Registration—

URL:
http://clinicaltrials.gov/show/NCT00209274
. Unique identifiers: NCT00209339 and NCT00209274.
Neuromechanical Features of the Cardiac Baroreflex After Exercise
Authors: Willie Christopher K. , Ainslie Philip N. , Taylor Chloe E. , Jones Helen , Sin Peter Y.W. , Tzeng Yu-Chieh
Published: March 2011

A single bout of exercise is associated with postexercise hypotension, transient decreases in autonomic function, and changes in baroreflex sensitivity. The baroreflex is less sensitive to falling blood pressure than to rising blood pressure; we characterized the cardiac baroreflex in terms of hysteresis and its mechanical and neural components. We hypothesized that hysteresis would be exacerbated postexercise because of a greater relative decrease in falling blood pressure. In 10 healthy young humans (5 men), we used bolus injections of sodium nitroprusside and phenylephrine hydrochloride to drive transient decreases and increases in blood pressure, respectively, to quantify cardiac baroreflex sensitivity to falling and rising blood pressure. This was completed before and at 10, 30, and 60 minutes after 40 minutes of cycling at 60% estimated maximal oxygen consumption. Analyses of beat-to-beat blood pressure, R-R intervals and heart rate, and carotid artery diameter were used to determine the integrated cardiac baroreflex response; this was further quantified into a mechanical component (systolic blood pressure versus carotid diameter) and a neural component (carotid diameter versus R-R interval). There were 2 principle findings: after aerobic exercise baroreflex sensitivity is reduced and hysteresis manifests, and the reduction in sensitivity to falling blood pressure is mediated by decreased mechanical and neural gains, whereas the decreased baroreflex sensitivity to rising blood pressure is mediated by a reduced mechanical gain only. We suggest that impaired neural transduction of the cardiac baroreflex, and its influence on hysteresis, plays an important role in transient autonomic dysfunction after exercise.
The Role of Moisture–Convection Feedbacks in Simulating the Madden–Julian Oscillation
Authors: Hannah Walter M. , Maloney Eric D.
Published: March 2011

The sensitivity of a simulated Madden–Julian oscillation (MJO) was investigated in the NCAR Community Atmosphere Model 3.1 with the relaxed Arakawa–Schubert convection scheme by analyzing the model’s response to varying the strength of two moisture sensitivity parameters. A higher value of either the minimum entrainment rate or rain evaporation fraction results in increased intraseasonal variability, a more coherent MJO, and enhanced moisture–convection feedbacks in the model. Changes to the mean state are inconsistent between the two methods. Increasing the minimum entrainment leads to a cooler and drier troposphere, whereas increasing the rain evaporation fraction causes warming and moistening. These results suggest that no straightforward correspondence exists between the MJO and the mean humidity, contrary to previous studies.

Analysis of the mean column-integrated and normalized moist static energy (MSE) budget reveals a substantial reduction of gross moist stability (GMS) for increased minimum entrainment, while no significant changes are found for an increased evaporation fraction. However, when considering fluctuations of the normalized MSE budget terms during MJO events, both methods result in negative GMS prior to the deep convective phase of the MJO. Intraseasonal fluctuations of GMS, rather than the mean, appear to be a better diagnostic quantity for testing a model’s ability to produce an MJO.
The Interaction Between Deep Convection and Easterly Waves over Tropical North Africa: A Weather State Perspective
Authors: Mekonnen Ademe , Rossow William B.
Published: March 2011

The interaction between deep convection and easterly waves over tropical North Africa is studied using a weather state (WS) dataset from the International Cloud Climatology Project (ISCCP) and reanalysis products from the European Centre for Medium-Range Weather Forecast, as well as radiative fluxes from ISCCP and a precipitation dataset from the Global Precipitation Climatology Project. Composite analysis based on 21 yr of data shows that stronger latent and radiative heating of the atmosphere are associated with stronger, more organized, convective activity than with weaker, less organized, convective activity, implying that any transition from less to more organized and stronger convection increases atmospheric heating. Regression composites based on a meridional wind predictor reveal coherent westward propagation of WS and large-scale wind anomalies from the Arabian Sea into East Africa and through West Africa. The analysis shows that enhanced, but unorganized, convective activity, which develops over the Arabian Sea and western Indian Ocean, switches to organized convective activity prior to the appearance of the African easterly wave (AEW) signature. The results also suggest that low-level moisture flux convergence and the upper-tropospheric wind divergence facilitate this change. Thus, the upper-level easterly waves, propagating into East Africa from the Indian Ocean, enhance one form of convection, which interacts with the Ethiopian highlands to trigger another, more organized, form of convection that, in turn, initiates the low-level AEWs.
Effects of Tropical Cyclones on Ocean Heat Transport in a High-Resolution Coupled General Circulation Model
Authors: Scoccimarro Enrico , Gualdi Silvio , Bellucci Alessio , Sanna Antonella , Giuseppe Fogli Pier , Manzini Elisa , Vichi Marcello , Oddo Paolo , Navarra Antonio
Published: March 2011

In this paper the interplay between tropical cyclones (TCs) and the Northern Hemispheric ocean heat transport (OHT) is investigated. In particular, results from a numerical simulation of the twentieth-century and twenty-first-century climates, following the Intergovernmental Panel on Climate Change (IPCC) twentieth-century run (20C3M) and A1B scenario protocols, respectively, have been analyzed. The numerical simulations have been performed using a state-of-the-art global atmosphere–ocean–sea ice coupled general circulation model (CGCM) with relatively high-resolution (T159) in the atmosphere. The CGCM skill in reproducing a realistic TC climatology has been assessed by comparing the model results from the simulation of the twentieth century with available observations. The model simulates tropical cyclone–like vortices with many features similar to the observed TCs. Specifically, the simulated TCs exhibit realistic structure, geographical distribution, and interannual variability, indicating that the model is able to capture the basic mechanisms linking the TC activity with the large-scale circulation. The cooling of the surface ocean observed in correspondence of the TCs is well simulated by the model. TC activity is shown to significantly increase the poleward OHT out of the tropics and decrease the poleward OHT from the deep tropics on short time scales. This effect, investigated by looking at the 100 most intense Northern Hemisphere TCs, is strongly correlated with the TC-induced momentum flux at the ocean surface, where the winds associated with the TCs significantly weaken (strengthen) the trade winds in the 5°–18°N (18°–30°N) latitude belt. However, the induced perturbation does not impact the yearly averaged OHT. The frequency and intensity of the TCs appear to be substantially stationary through the entire 1950–2069 simulated period, as does the effect of the TCs on the OHT.
Expanding Current EVAR Indications to Include Small Abdominal Aortic Aneurysms: A Glimpse of the Future
Authors: Georgakarakos Efstratios , Ioannou Christos V. , Georgiadis George S. , Kapoulas Konstantinos , Schoretsanitis Nikolaos , Lazarides Miltos
Published: March 2011

The traditional criterion of maximum transverse diameter is not sufficient to differentiate the small abdominal aortic aneurysms (AAAs) that are either prone to rupture or prone to enlarge rapidly. Wall stress may be a more reliable indicator with respect to these tasks. We review the importance of geometric features in rupture- or growth-predictive models and stress the need for further evaluation and validation of geometric indices. This study may lead to identifying those small AAAs that could justify early endovascular intervention.
The Relationship Between Chronic Kidney Disease and SYNTAX Score
Authors: Coskun Ugur , Orta Kilickesmez Kadriye , Abaci Okay , Kocas Cuneyt , Bostan Cem , Yildiz Ahmet , Baskurt Murat , Arat Alev , Ersanli Murat , Gurmen Tevfik
Published: March 2011

Chronic kidney disease (CKD) is associated with increased risk of cardiovascular disease and death. We evaluated the association between CKD and severity of coronary artery stenosis by calculating SYNTAX Score in patients with left main coronary artery and/or 3-vessel coronary artery disease. Coronary angiograms of 217 patients were assessed. Chronic kidney disease was staged using the estimated glomerular filtration rate (eGFR, mL/min per 1.73 m2) prior to coronary angiography. Patients were divided into 5 groups according to the National Kidney Foundation Kidney Disease Outcome Quality Initiative (NKF KDOQI) Clinical Practice Guidelines (14). Patients with eGFR >90 mL/min per 1.73 m2 (group 1), patients with eGFR 60 to 89 mL/min per 1.73 m2 (group 2), patients with eGFR 30 to 59 mL/min per 1.73 m2 (group 3), patients with eGFR >15 to < 30 per 1.73 m2 and dialysis patients with eGFR < 15 per 1.73 m2 were combined as group 4. The risk of significant lesion complexity increased progressively with decreasing kidney function (P = .001). Estimated glomerular filtration rate was a strong predictor of higher SYNTAX Score.
Éléments de compréhension sur la praxis ludique de Jésus le Christ
Authors: Deschênes Gervais
Published: March 2011

Cet article présente des éléments de compréhension théologique de la praxis ludique de Jésus le Christ. Nous explorons tout d’abord les catégories de la fête en interprétant les noces de Cana sous l’angle de la dimension symbolique du vin, du « miracle-don », de la consécration du plaisir sexuel et de la procréation ainsi que de l’annonce du Royaume de Dieu que nous propose ce signe évangélique. Par la suite, nous porterons un regard sur le rire comme chemin d’espérance en évoquant le statut du rire chez les chrétiens et dans la Bible. Une attention particulière sera donnée sur le rire de Jésus et du jeu ironique de sa passion en empruntant au théologien Harvey Cox l’image du Christ-Arlequin qui ouvre à la compréhension de la dimension eschatologique de la résurrection.
Self-Transcendence as the Ultimate Reality in Interreligious Dialogue: A Neo-Confucian Perspective
Authors: Chung Edward Y.J.
Published: March 2011

This article presents the Confucian teaching of self-transcendence and its modern implications for interreligious dialogue. It first points out that most scholars in the field of interreligious dialogue share a common tendency to rely very heavily on Western concepts and/or Christian theological approaches. My discussion of self-transcendence is based on the classical teaching of Confucius and Mencius and its leading interpretation by two eminent Neo-Confucian thinkers, Chu Hsi (1130—1200) and Yi T’oegye (1501—1570). I present this core textual tradition while consulting its modern interpreters and some key examples of Confucian practice. Human beings have the potential to work toward perfection (sagehood), and embedded in this doctrine is a religious belief in the oneness of Heaven and human nature. We need to explore a new approach to the interreligious discussion of ‘‘ultimate reality’’ by considering Neo-Confucianism. A dialogue between the Neo-Confucian vision of self-transcendence and the converging heart of world religions will enhance the global enterprise of comparative religion.
Toward an Alternative Explanation for the Resource Curse: Natural Resources, Immigration, and Democratization
Authors: Bearce David H. , Laks Hutnick Jennifer A.
Published: March 2011

Why do many resource-rich countries maintain autocratic political regimes? The authors’ proposed answer focuses on the causal effect of labor imports, or immigration. Using the logic offered by Acemoglu and Robinson’s democratization model, the authors posit that immigration makes democratization less likely because it facilitates redistributive concessions to appease the population within an autocratic regime. This immigration argument applies directly to the political resource curse since many resource-rich countries tend to also be labor scarce, leading them to import foreign laborers. Consistent with this understanding, the authors find a statistically significant negative relationship between net immigration per capita and democratization in future periods. Their results also show that when controlling for this immigration effect, the standard resource curse variables lose significance in a democratization model. This latter result suggests that much of the so-called resource curse stems not from resource endowments per se but rather from the labor imports related to resource production.
Observed Score Equating Using a Mini-Version Anchor and an Anchor with Less Spread of Difficulty: A Comparison Study
Authors: Liu Jinghua , Sinharay Sandip , Holland Paul , Feigenbaum Miriam , Curley Edward
Published: March 2011

Two different types of anchors are investigated in this study: a mini-version anchor and an anchor that has a less spread of difficulty than the tests to be equated. The latter is referred to as a midi anchor. The impact of these two different types of anchors on observed score equating are evaluated and compared with respect to systematic error (bias), random equating error (SEE), and total equating error (RMSE) using SAT operational data. The results suggest that the overall bias, SEE, and RMSE when the midi anchor is used are either smaller than or very similar to those when the mini anchor test is used. The findings suggest that a midi anchor test would be preferred to a mini anchor test if equating accuracy at the ends of the score scale is not a primary concern.
Estimating the Effect of Changes in Criterion Score Reliability on the Power of the F Test of Equality of Means
Authors: Feldt Leonard S.
Published: March 2011

This article presents a simple, computer-assisted method of determining the extent to which increases in reliability increase the power of the F test of equality of means. The method uses a derived formula that relates the changes in the reliability coefficient to changes in the noncentrality of the relevant F distribution. A readily available computer applet translates the noncentrality parameter into the power value of the F test.
The Reliability Paradox in Assessing Structural Relations Within Covariance Structure Models
Authors: Hancock Gregory R. , Mueller Ralph O.
Published: March 2011

A two-step process is commonly used to evaluate data–model fit of latent variable path models, the first step addressing the measurement portion of the model and the second addressing the structural portion of the model. Unfortunately, even if the fit of the measurement portion of the model is perfect, the ability to assess the fit within the structural portion is affected by the quality of the factor–variable relations within the measurement model. The result is that models with poorer quality measurement appear to have better data–model fit, whereas models with better quality measurement appear to have worse data–model fit. The current article illustrates this phenomenon across different classes of fit indices, discusses related structural assessment problems resulting from issues of measurement quality, and endorses a supplemental modeling step evaluating the structural portion of the model in isolation from the measurement model.
A Note on Comparing Examinee Classification Methods for Cognitive Diagnosis Models
Authors: Huebner Alan , Wang Chun
Published: March 2011

Cognitive diagnosis models have received much attention in the recent psychometric literature because of their potential to provide examinees with information regarding multiple fine-grained discretely defined skills, or attributes. This article discusses the issue of methods of examinee classification for cognitive diagnosis models, which are special cases of restricted latent class models. Specifically, the maximum likelihood estimation and maximum a posteriori classification methods are compared with the expected a posteriori method. A simulation study using the Deterministic Input, Noisy-And model is used to assess the classification accuracy of the methods using various criteria.
Disparities in Periodontitis Prevalence among Chronic Kidney Disease Patients
Authors: Ioannidou E. , Swede H.
Published: March 2011

Because of adverse effects of uremia in the innate and adaptive immune systems, we hypothesized that chronic kidney disease (CKD) patients would have higher prevalence of moderate periodontitis compared with individuals without CKD. We examined this hypothesis using the NHANES III dataset, including 12,081 adults stratified by Race-Ethnicity. We followed the American Academy of Periodontology/Centers for Disease Control and Prevention definition for moderate periodontitis. Estimated glomerular filtration rate (GFR) was calculated based on calibrated serum creatinine levels according to the Modification of Diet in Renal Disease Study formula. Analyses incorporated NHANES sampling weights. Overall, 14.6% of individuals with CKD were classified as having moderate periodontitis, compared with 8.7% in the non-CKD group (p = 0.001). A significant dose-response association (p = 0.001) was observed between prevalence of moderate periodontitis and CKD stages among non-Hispanic Blacks and Mexican-Americans, but not so for non-Hispanic Whites. Prevalence of periodontitis among participants with CKD was substantially higher among non-Hispanic Blacks (38.9%) and Mexican-Americans (37.3%) compared with non-Hispanic Whites (12.9%). Multivariate logistic regression models showed that Mexican-Americans and non-Hispanic Blacks with CKD were approximately 30% to 60% more likely to have moderate periodontitis compared with those without CKD, after adjustment for diabetes status and other potential confounders.