bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk of cancer in relatives of patients with myotonic dystrophy: a population‐based cohort study
Authors: Lund M. , Diaz L. J. , Gørtz S. , Feenstra B. , Duno M. , Juncker I. , Eiberg H. , Vissing J. , Wohlfahrt J. , Melbye M.
Published: May 2014

Background and purpose

Myotonic dystrophies (DM) are autosomal dominantly inherited neuromuscular disorders caused by unstable nucleotide repeat expansions. DM and cancer have been associated, but the pathogenesis behind the association remains unclear. It could relate to derived effects of the DM genotype in which case non‐DM relatives of DM patients would not be expected to be at increased risk of cancer. To elucidate this, a population‐based cohort study investigating risk of cancer in relatives of DM patients was conducted.

Methods

DM was identified using the National Danish Patient Registry and results of genetic testing. Information on cancer was obtained from the Danish Cancer Registry. A population‐based cohort of 5 757 565 individuals with at least one relative was established using the Danish Family Relations Database based on kinship links in the Danish Civil Registration System. Familial aggregation of cancer was evaluated by (incidence) rate ratios (RRs) comparing the rate of cancer amongst relatives of patients with DM from 1977 to 2010 (exposed) with the rate of cancer amongst persons with a relative of the same type but without DM (non‐exposed).

Results

In first‐degree relatives of individuals with DM the adjusted RR of cancer was 0.89 (95% confidence interval 0.71–1.12) overall, and in stratified analyses 0.68 (0.37–1.12) before age 50 and 0.96 (0.74–1.23) at age 50 or older.

Conclusions

The present study does not support an increased risk of cancer in non‐DM relatives of DM patients suggesting that cancer and DM are associated through derived effects of the DM genotype.
Association between migraine and irritable bowel syndrome: a population‐based retrospective cohort study
Authors: Lau C.‐I. , Lin C.‐C. , Chen W.‐H. , Wang H.‐C. , Kao C.‐H.
Published: May 2014

Background and purpose

Migraine and irritable bowel syndrome (IBS) share many similarities characterized by their epidemiology, periodic pain, lack of definable organic causes, trigger factors, comorbidities and proposed pathophysiology. In this retrospective case–control study, the association between migraine and IBS was investigated using a nationwide population‐based database in Taiwan.

Methods

The data were retrieved from the National Health Insurance Research Database (NHIRD) of Taiwan. In all, 14 117 newly diagnosed migraine cases were identified in a subset of the NHIRD and 56 468 migraine‐free individuals were randomly selected as the comparison cohort. The multivariate Cox proportional hazards regression model was used to explore the risk of IBS in migraine sufferers after adjusting for demographic characteristics and comorbidities.

Results

After adjusting for the covariates, the incidence of IBS was 1.95‐fold higher in the migraine cohort than in the comparison cohort (73.87 vs. 30.14 per 10 000 person‐years). The adjusted cumulative incidence of IBS was also higher in the migraine group than in the control group in the follow‐up years (log‐rank test, P < 0.0001). In addition, the risk was most prominent in the youngest group (<30 years old), exhibiting a 3.36‐fold increased risk (95% confidence interval 2.44–4.63) of IBS compared with the migraine‐free cohort. Moreover, the incidence of IBS in migraine sufferers tended to increase with the frequency of migraine diagnoses.

Conclusion

The current population‐based study demonstrated that migraine is associated with an increased risk of IBS after adjusting for comorbidities, particularly in the young population.
Next‐generation sequencing improves the diagnosis of thyroid FNA specimens with indeterminate cytology
Authors: Le Mercier Marie , D'Haene Nicky , De Nève Nancy , Blanchard Oriane , Degand Caroline , Rorive Sandrine , Salmon Isabelle
Published: May 2014

Aims

The assessment of thyroid nodules is a common clinical challenge. Fine‐needle aspiration (FNA) is the standard pre‐operative tool for thyroid nodule diagnosis. However, up to 30% of the samples are classified as indeterminate. This often leads to unnecessary surgery. In this study, we evaluated the added value of next‐generation sequencing (NGS) for helping in the diagnosis of FNA samples.

Methods and results

We analysed retrospectively 34 indeterminate FNA samples for which surgical resection was performed. DNA was obtained from cell blocks or from stained smears and subjected to NGS to analyse mutations in 50 genes. Mutations in BRAF, NRAS, KRAS and PTEN, that are known to be involved in thyroid cancer biology, were detected in seven FNA samples. The presence of a mutation in these genes was a strong indicator of cancer because five (71%) of the mutation‐positive FNA samples had a malignant diagnosis after surgery. Moreover, there was only an 8% cancer risk in nodules with an indeterminate cytological diagnosis but with a negative molecular test.

Conclusion

This study demonstrates that thyroid FNA can be analysed successfully by NGS. The detection of mutations known to be involved in thyroid cancer improves the sensitivity of thyroid FNA diagnosis.
Molecular characterization and differentiation of five horse breeds raised in Algeria using polymorphic microsatellite markers
Authors: Berber N. , Gaouar S. , Leroy G. , Kdidi S. , Tabet Aouel N. , Saïdi Mehtar N.
Published: May 2014

In this study, genetic analyses of diversity and differentiation were performed on five horse breeds raised in Algeria (Barb, Arab‐Barb, Arabian, Thoroughbred and French Trotter). All microsatellite markers were highly polymorphic in all the breeds. A total of 123 alleles from 14 microsatellite loci were detected in 201 horses. The average number of alleles per locus was the highest in the Arab‐Barb horses (7.86) and lowest in the thoroughbred breed (5.71), whereas the observed and expected heterozygosities per breed ranged from 0.71 (Thoroughbred) to 0.752 (Barb) and 0.71 (Thoroughbred) to 0.77 (Arab‐Barb), respectively. The genetic differentiation between the breeds was significant (p < 0.01) based on the infinitesimal model (FST). Three different approaches for evaluating the genetic relationships were applied. Genetic distances, the factorial correspondence analysis and structure analysis showed that a significant amount of genetic variation is maintained in the native horse populations and the other breeds. The Barb and Arab‐Barb breeds seem to be the most genetically related and support the decision to consider the breeds as same population.
Use of robust multivariate linear mixed models for estimation of genetic parameters for carcass traits in beef cattle
Authors: Peters S.O. , Kizilkaya K. , Garrick D.J. , Fernando R.L. , Pollak E.J. , Enns R.M. , De Donato M. , Ajayi O.O. , Imumorin I.G.
Published: May 2014

Assumptions of normality of residuals for carcass evaluation may make inferences vulnerable to the presence of outliers, but heavy‐tail densities are viable alternatives to normal distributions and provide robustness against unusual or outlying observations when used to model the densities of residual effects. We compare estimates of genetic parameters by fitting multivariate Normal (MN) or heavy‐tail distributions (multivariate Student's t and multivariate Slash, MSt and MS) for residuals in data of hot carcass weight (HCW), longissimus muscle area (REA) and 12th to 13th rib fat (FAT) traits in beef cattle using 2475 records from 2007 to 2008 from a large commercial operation in Nebraska. Model comparisons using deviance information criteria (DIC) favoured MSt over MS and MN models, respectively. The posterior means (and 95% posterior probability intervals, PPI) of v for the MSt and MS models were 5.89 ± 0.90 (4.35, 7.86) and 2.04 ± 0.18 (1.70, 2.41), respectively. Smaller values of posterior densities of v for MSt and MS models confirm that the assumption of normally distributed residuals is not adequate for the analysis of the data set. Posterior mean (PM) and posterior median (PD) estimates of direct genetic variances were variable with MSt having the highest mean value followed by MS and MN, respectively. Posterior inferences on genetic variance were, however, comparable among the models for FAT. Posterior inference on additive heritabilities for HCW, REA and FAT using MN, MSt and MS models indicated similar and moderate heritability comparable with the literature. Posterior means of genetic correlations for carcass traits were variable but positive except for between REA and FAT, which showed an antagonistic relationship. We have demonstrated that genetic evaluation and selection strategies will be sensitive to the assumed model for residuals.
Characteristics of periodontal biotype, its dimensions, associations and prevalence: a systematic review
Authors: Zweers Jeroen , Thomas Renske Z. , Slot Dagmar E. , Weisgold Arnold S. , Van der Weijden Fridus G. A.
Published: May 2014

Aim

The objectives of this review were as follows: What are characteristics used to define various forms of periodontal biotypes? What are their anatomic dimensions in relation to the definition? In addition, what is the association between these various characteristics in relation to the periodontal biotypes? Furthermore, what is the prevalence of various forms of periodontal biotypes in the population?

Material and Methods

The PubMed‐MEDLINE, the Cochrane‐CENTRAL and EMBASE databases were searched through up and till June 2013 to identify any appropriate studies regarding the aim. Appropriate studies were those reporting characteristics of various forms of periodontal biotype and its dimensions. These characteristics were gingival thickness (GT), gingival morphotype (GM), tooth dimensions (TD), keratinized tissue (KT) and bone morphotype (BM).

Results and Conclusions

The search yielded 2581 unique papers, after selection resulted in 12 publications that met the eligibility criteria. In general, the available definitions are found to be unclear and sometimes inconsistent. However, based on the available literature, the three biotypes thin scalloped, thick flat and thick scalloped seem a comprehensive categorization in defining periodontal biotypes in the population. The dental, gingival and osseous dimensions have a weak to moderate association. Only between gingival thickness, keratinized tissue and bone morphotype uniform positive associations are found.
Reading and language intervention for children at risk of dyslexia: a randomised controlled trial
Authors: Duff Fiona J. , Hulme Charles , Grainger Katy , Hardwick Samantha J. , Miles Jeremy N.V. , Snowling Margaret J.
Published: May 2014

Background

Intervention studies for children at risk of dyslexia have typically been delivered preschool, and show short‐term effects on letter knowledge and phoneme awareness, with little transfer to literacy.

Methods

This randomised controlled trial evaluated the effectiveness of a reading and language intervention for 6‐year‐old children identified by research criteria as being at risk of dyslexia (n = 56), and their school‐identified peers (n = 89). An Experimental group received two 9‐week blocks of daily intervention delivered by trained teaching assistants; the Control group received 9 weeks of typical classroom instruction, followed by 9 weeks of intervention.

Results

Following mixed effects regression models and path analyses, small‐to‐moderate effects were shown on letter knowledge, phoneme awareness and taught vocabulary. However, these were fragile and short lived, and there was no reliable effect on the primary outcome of word‐level reading.

Conclusions

This new intervention was theoretically motivated and based on previous successful interventions, yet failed to show reliable effects on language and literacy measures following a rigorous evaluation. We suggest that the intervention may have been too short to yield improvements in oral language; and that literacy instruction in and beyond the classroom may have weakened training effects. We argue that reporting of null results makes an important contribution in terms of raising standards both of trial reporting and educational practice.
Evidence of genetic change in the flowering phenology of sea beets along a latitudinal cline within two decades
Authors: Van Dijk H. , Hautekèete N.‐C.
Published: May 2014

Sea beets grown from seeds collected in 1989 and 2009 along the coasts of France and adjacent regions were compared for flowering date under controlled conditions. Seeds from both collection years were sown simultaneously and cultivated under the same glasshouse conditions. Date of flowering onset and year of first flowering were recorded. There was an overall northward shift in flowering time of about 0.35° latitude (i.e. 39 km) over the 20‐year period. The southern portion of the latitudinal gradient – that is, from 44.7°N to 47.28°N – flowered significantly later by a mean of 1.78 days, equivalent to a 43.2‐km northward shift of phenotypes. In the northern latitudes between 48.6°N and 52°N, flowering date was significantly earlier by a mean of 4.04 days, corresponding to a mean northward shift of 104.9 km, and this shift was apparently due to a diminished requirement of exposure to cold temperatures (i.e. vernalization), for which we found direct and indirect evidence. As all plants were grown from seed under identical conditions, we conclude that genetic changes occurred in the sensitivity to environmental cues that mediate the onset of flowering in both the northern and the southern latitudes of the gradient. Microevolution and gene flow may have contributed to this change. There was no significant change in the frequency of plants that flowered without vernalization. The lack of vernalization requirement may be associated with environmental instability rather than with climate conditions.
Pharmacokinetic evaluation of tenofovir disoproxil fumarate released from an intravaginal ring in pigtailed macaques after 6 months of continuous use
Authors: Srinivasan Priya , Dinh Chuong , Zhang Jining , Pau Chou‐Pong , McNicholl Janet M. , Lo Yungtai , Herold Betsy C. , Teller Ryan , Kiser Patrick , Smith James M.
Published: May 2014

Background and Methods

A reservoir intravaginal ring (IVR) eluting tenofovir disoproxil fumarate (TDF) was evaluated for 6 months of continuous use in normally cycling female pigtailed macaques with monthly IVR exchanges to define pharmacokinetics and safety.

Results and Conclusions

Tenofovir levels in vaginal secretions and tissue remained consistent for 6 months with no adverse safety concerns.
Sinus of Valsalva: a converging nozzle that contributes to stable flow in the coronary arteries
Authors: Stein Paul D. , Blick Edward F. , Shields Sarah Kim , Matta Fadi
Published: May 2014

The anatomy of the sinuses of Valsalva has not been considered from the viewpoint of a converging nozzle. Converging nozzles reduce turbulence. We reviewed computed tomographic images of the left and right sinuses of Valsalva in 20 consecutive patients. The sinuses of Valsalva were shown to have a shape in the axial projection that approximates a cubic equation nozzle, although the sinuses of Valsalva are not axisymmetric. The ratios of the cross‐sectional area of the inlet to cross‐sectional areas of the outlet, assuming the sinuses are axisymmetric, were 14 and 17 in the left and right sinuses, respectively. Calculations by others show that turbulent kinetic energy at the exit (at the coronary ostia) of such axisymmetric nozzles would be reduced by 97%. We conclude that the sinuses of Valsalva have the configuration of a converging nozzle and prevent or reduce turbulent flow in the proximal portions of the coronary arteries.
Recognition of patient‐reported impairment in oral aesthetics
Authors: Dannemand K. , Özhayat E. B.
Published: May 2014

The objectives of this study were to investigate the degree of effective recognition by professionals of patient‐estimated oral aesthetic impairment and the most reliable aspects in such recognition. Participants consisted of 95 patients with partial dentition in need of prosthodontic replacements. The oral aesthetics was professionally evaluated using the Prosthetic Esthetic Index (PEI), compiling 13 aesthetic aspects and an overall evaluation. The patient‐reported impairment was evaluated using the Oral Health Impact Profile Aesthetic (OHIP‐Aes) and the Oral Esthetic Scale (OES). Background variables were as follows: gender, age, work situation, education level, marital status, number and location of teeth, wearing a removable dental prosthesis (RDP) and smile line. A significant correlation was found between the overall professional evaluation and the OHIP‐Aes score (R = 0·43, P < 0·05), the OES score (R = 0·46, P < 0·05) and the overall patient evaluation (0·35, P < 0·05). Correlations of the 13 specific aspects of the PEI with the patient‐reported evaluations were generally small to moderate: the aspect ‘discoloration of the teeth’ showed the highest correlation. The multivariate analyses showed that up to 57% of the patient‐reported impairment could be explained by the professionally evaluated oral aesthetic in combination with background variables. Discoloration of the teeth was the greatest explanatory variable, but also dental arch symmetry, and position and colour of the teeth were significant aspects. A high percentage of the patient‐reported aesthetic impairment can be recognised by the professionals. The most reliable aspect is discoloration of the teeth, but also dental arch symmetry, and the position and colour of the teeth are important for recognising the aesthetic impairment.
Genetic Diversity of Thanatephorus cucumeris Infecting Tomato in Iran
Authors: Pourmahdi Atena , Taheri Parissa
Published: May 2014

The necrotrophic fungus Thanatephorus cucumeris (anamorph Rhizoctonia solani) is among the most important soil‐borne pathogens which causes tomato foot and root rot worldwide. We investigated virulence and genetic relationships among and within different taxonomic groups of R. solani from the tomato‐growing regions in the north‐east of Iran. Characterization of R. solani taxonomic groups revealed that, of 56 isolates, four were AG‐2‐1, 16 were AG‐3 PT, 21 were AG‐4 HG‐I and 15 were AG‐4 HG‐II. Because interprimer binding site (iPBS), which is based on amplification of retrotransposons, is known as novel and powerful DNA fingerprinting technology, we selected four iPBS primers, which can detect polymorphisms of tomato foot root and root rot pathogen, for investigating genotypic variability of the isolates. The iPBS analyses separated various taxonomic groups of R. solani and showed great diversity among the isolates, demonstrating that the R. solani isolates obtained from tomato were not a clonal population. Crop rotation strategies and geographic location seem to be important factors affecting genetic structure of the isolates. Pathogenicity tests on tomato cultivar ‘Mobil’ showed significant differences in the virulence of various isolates. The overall results indicated that isolates of AG‐3 and AG‐4 were more virulent than AG‐2‐1. There was no significant correlation between genetic diversity and virulence of the isolates. This is the first report of R. solani AG‐4 HG‐II, causing tomato foot and root rot. Also, our research is the first in assessment of genetic diversity in fungal populations using iPBS molecular markers.
Development of an enzyme-linked immunosorbent assay for Bartonella henselae infection detection
Authors: Ferrara F. , Di Niro R. , D'Angelo S. , Busetti M. , Marzari R. , Not T. , Sblattero D.
Published: May 2014

Several serological diagnostics rely on enzyme-linked immunosorbent assay (ELISA) to detect bacterial infections. However, for some pathogens, including Bartonella henselae, diagnosis still depends on manually intensive, time-consuming assays including micro-immunofluorescence, Western blotting or indirect immunofluorescence. For such pathogens, there is obviously still a need to identify antigens to establish a reliable, fast and high-throughput assay (Dupon et al. 8). We evaluated two B. henselae proteins to develop a novel serological ELISA: a well-known antigen, the 17-kDa protein, and GroEL, identified during this study by a proteomic approach. When serum IgG were tested, the specificity and sensitivity were 76 and 65·7% for 17-kDa, respectively, and 82 and 42·9% for GroEL, respectively. IgM were found to be more sensitive and specific for both proteins: 17-kDa protein, specificity 86·2% and sensitivity 75%; GroEL, specificity 97·7% and sensitivity 45·3%. IgM antibodies were also measured in lymphoma patients and patients with Mycobacterium tuberculosis infection to assess the usefulness of our ELISA to distinguish them from B. henselae infected patients. The resulting specificities were 89·1 and 93·5% for 17-kDa protein and GroEL, respectively. Combining the results from the two tests, we obtained a sensitivity of 82·8% and a specificity of 83·9%. Our work described and validated a proteomic approach suitable to identify immunogenic proteins useful for developing a serological test of B. henselae infection.

Significance and Impact of the Study

A reliable serological assay for the diagnosis of Cat Scratch Disease (CSD) – a pathological condition caused by Bartonella henselae infection – has not yet been developed. Such an assay would be extremely useful to discriminate between CSD and other pathologies with similar symptoms but different aetiologies, for example lymphoma or tuberculosis. We investigate the use of two B. henselae proteins – GroEL and 17-kDa – to develop a serological-based ELISA, showing promising results with the potential for further development as an effective tool for the differential diagnosing of B. henselae infection.
The chronic use of beta‐blockers and proton pump inhibitors may affect the rate of bacterial infections in cirrhosis
Authors: Merli Manuela , Lucidi Cristina , Di Gregorio Vincenza , Giannelli Valerio , Giusto Michela , Ceccarelli Giancarlo , Riggio Oliviero , Venditti Mario
Published: May 2014

Background & Aims

Bacterial infections are among the most common and life‐threatening complications in cirrhosis. Qualitative and quantitative modifications of the gut microbiota, dysfunction of the intestinal barrier and multiple immune defects are factors that contribute to a pathological ‘bacterial translocation’ (BT), leading to a higher susceptibility to infections in cirrhotic patients. Long‐term therapies, commonly adopted in cirrhotic patients, may influence BT and modify the risk of infection in these patients. To investigate the influence of chronic therapies on the prevalence and microbiological characteristics of infections in cirrhosis.

Methods

Consecutive cirrhotic patients hospitalised from 2008 to 2013 were enrolled. All previous treatments were carefully recorded. Infections were actively sought out, patients were actively monitored for infection, and possible risk factors were evaluated.

Results

Four hundred cirrhotic patients were included. The most frequent therapies were proton pump inhibitors (PPIs) (67%), non‐absorbable‐disaccharides (44%), beta‐blockers (BBs) (39%) and non‐absorbable‐antibiotics (10%). Child‐Pugh C (P < 0.001; OR 5; 95%CI: 2.6–9.9) and PPI therapy (P = 0.008; OR 2; 95% CI: 1.2–3.2) were found to be independent predictors of infection, and the use of BBs was a protective factor (P = 0.001; OR 0.46; 95%CI: 0.3–0.7). Cirrhotic patients with bacterial infection showed lower morbidity and mortality when taking BBs.

Conclusions

Proton pump inhibitors increase the risk of infection in cirrhosis and should not be prescribed in these patients without specific indications. In contrast, the use of BBs is associated with a lower rate of infection and attenuates the consequences of infections in cirrhotic patients.
No Virological Evidence for an Influenza A ‐ like Virus in European Bats
Authors: Fereidouni S. , Kwasnitschka L. , Balkema Buschmann A. , Müller T. , Freuling C. , Schatz J. , Pikula J. , Bandouchova H. , Hoffmann R. , Ohlendorf B. , Kerth G. , Tong S. , Donis R. , Beer M. , Harder T.
Published: May 2014

New members of the influenza A virus genus have been detected recently in bats from South America. By molecular investigations, using a generic real‐time RT‐PCR (RT‐qPCR) that detects all previously known influenza A virus subtypes (H1‐H16) and a newly developed RT‐qPCR specific for the South American bat influenza‐like virus of subtype H17, a total of 1571 samples obtained from 1369 individual bats of 26 species from Central Europe were examined. No evidence for the occurrence of such influenza viruses was found. Further attempts towards a more comprehensive evaluation of the role of bats in the ecology and epidemiology of influenza viruses should be based on more intense monitoring efforts. However, given the protected status of bats, not only in Europe, such activities need to be embedded into existing pathogen‐monitoring programs.
Impact of endothelin blockade on acute exercise‐induced changes in blood flow and endothelial function in type 2 diabetes mellitus
Authors: Schreuder Tim H. A. , van Lotringen Jaap H. , Hopman Maria T. E. , Thijssen Dick H. J.
Published: May 2014

New Findings

What is the central question of this study?

Doesendothelin receptor blockade increase exercise‐induced blood flow and post‐exercise endothelial function in men with type 2 diabetes?

What is the main finding and its importance?

Despite increasing exercise‐induced blood flow, endothelin receptor blockade did not impact post‐exercise endothelial function. The increase in blood flow may have beneficial effects in repeated exercise training.

Positive vascular effects of exercise training are mediated by acute increases in blood flow. Type 2 diabetes patients show attenuated exercise‐induced increases in blood flow, possibly mediated by the endothelin pathway, preventing an optimal stimulus for vascular adaptation. We examined the impact of endothelin receptor blockade (bosentan) on exercise‐induced blood flow in the brachial artery and on pre‐ and postexercise endothelial function in type 2 diabetes patients (n = 9, 60 ± 7 years old) and control subjects (n = 10, 60 ± 5 years old). Subjects reported twice to the laboratory to perform hand‐grip exercise in the presence of endothelin receptor blockade or placebo. We examined brachial artery endothelial function (via flow‐mediated dilatation) before and after exercise, as well as blood flow during exercise. Endothelin receptor blockade resulted in a larger increase in blood flow during exercise in type 2 diabetes patients (P = 0.046), but not in control subjects (P = 0.309). Exercise increased shear rate across the exercise protocol, unaffected by endothelin receptor blockade. Exercise did not alter brachial artery diameter in either group, but endothelin receptor blockade resulted in a larger brachial artery diameter in type 2 diabetes patients (P = 0.033). Exercise significantly increased brachial artery flow‐mediated dilatation in both groups, unaffected by endothelin receptor blockade. Endothelin receptor blockade increased exercise‐induced brachial artery blood flow in type 2 diabetes patients, but not in control subjects. Despite this effect of endothelin receptor blockade on blood flow, we found no impact on baseline or post‐exercise endothelial function in type 2 diabetes patients or control subjects, possibly related to normalization of the shear stimulus during exercise. The successful increase in blood flow during exercise in type 2 diabetes patients through endothelin receptor blockade may have beneficial effects in repeated exercise training.
Extracellular acidosis contracts coronary but neither renal nor mesenteric artery via modulation of H+,K+‐ATPase, voltage‐gated K+ channels and L‐type Ca2+ channels
Authors: Niu Longgang , Liu Yu , Hou Xiaomin , Cui Lijuan , Li Jiangtao , Zhang Xuanping , Zhang Mingsheng
Published: May 2014

New Findings

What is the central question of this study?

We asked whether there are any differences in responses to extracellular acidosis among arteries of different origin and whether K+ channels, Ca2+ channels and H+,K+‐ATPase are involved in extracellular acidosis‐induced coronary myogenic responses.

What is the main finding and its importance?

This report is the first to demonstrate that extracellular acidosis alkalinizes the cytosol of arterial smooth muscle cells freshly isolated from rat coronary artery and contracts the artery exclusively and to suggest that modulation of voltage‐gated K+ channels, voltage‐gated Ca2+ channels and H+,K+‐ATPase are involved in the contraction.

Extracellular acidosis (EA) jeopardizes the heart, whereas mild extracellular alkalinization is cardioprotective, but it remains elusive how the coronary artery (CA) responses to EA. In the present study, EA was demonstrated to induce contraction in rat coronary artery (RCA) in a manner dependent on extracellular pH (pHo, 7.2–6.6), whereas it did not affect the resting tone of either rat renal interlobe artery (RIA) or mesenteric artery (MA). The amplitude of contraction provoked by pHo 6.8 was approximately equal to that induced by 60 mmol l−1 KCl at pHo 7.4. Blockade of L‐type voltage‐gated Ca2+ channels and inhibition of H+,K+‐ATPase attenuated the contraction, whereas inhibition of nitric oxide synthesis and endothelial denudation augmented it. A molecular probe study showed that EA acidified the cytosol of arterial smooth muscle cells (ASMCs) in RIA and MA, but alkalinized it in RCA. Extracellular acidosis elevated the intracellular Ca2+ concentration exclusively in RCA ASMCs. Patch‐clamp studies showed that EA enhanced L‐type voltage‐gated Ca2+ channel currents in RCA ASMCs, but depressed the currents in MA ASMCs and did not affect the currents in RIA ASMCs. Extracellular acidosis depressed voltage‐gated K+ channel (KV) currents only in RCA ASMCs. Lansoprazole blunted all these observed effects of EA on RCA. Taken together, the present results demonstrate that the responses of RCA to EA are different from those of RIA and MA and suggest that activation of L‐type voltage‐gated Ca2+ channels and H+,K+‐ATPase as well as depression of KV may, at least partly, underlie the EA‐induced contraction in RCA.
A Hybrid Atomistic Approach for the Mechanics of Deoxyribonucleic Acid Molecules
Authors: Adhikari S. , Saavedra Flores E. I. , Scarpa F. , Chowdhury R. , Friswell M. I.
Published: May 2014

The paper proposes a new modeling approach for the prediction and analysis of the mechanical properties in deoxyribonucleic acid (DNA) molecules based on a hybrid atomistic-finite element continuum representation. The model takes into account of the complex geometry of the DNA strands, a structural mechanics representation of the atomic bonds existing in the molecules and the mass distribution of the atoms by using a lumped parameter model. A 13-base-pair DNA model is used to illustrate the proposed approach. The properties of the equivalent bond elements used to represent the DNA model have been derived. The natural frequencies, vibration mode shapes, and equivalent continuum mechanical properties of the DNA strand are obtained. The results from our model compare well with a high-fidelity molecular mechanics simulation and existing MD and experimental data from open literature.
Simulating Multizone Fracturing in Vertical Wells
Authors: Wang Wei , Dahi Taleghani Arash
Published: May 2014

Numerous multizone multistage hydraulic fracturing treatments are now being executed in low permeability oil and gas fields around the world. Due to the limited access to the subsurface, post-treatment assessments are mainly limited to few techniques such as tiltmeter, microseismic, and tracer-logs. The first two techniques are mainly used to determine fracture extension; however, fracture height and fracture initiation at all perforation clusters could only be confirmed through radioactive tracer logs or detailed pressure analysis. In this paper, we consider real examples from a field from Central America and investigate potential problems that led to the limited generation of fractures in multizone treatments. For instance, some of the postfrac radioactive logs show very low concentration of tracers at some perforated zones in comparison with other zones. On the other hand in some cases, tracer logs indicate the presence of tracers in deeper or shallower zones. Different reasons could cause fracture growth in nonperforated zones, including but not limited to: perforation design problems, casing/cement integrity problems, lack of containment, instability of fracture growth in one or some of the zones, and finally making a mistake in selecting lithology for fracturing. In this paper, some of these issues have been examined for a few sample wells using treatment pressure data, petrophysical logs, and postfrac tracer logs. Some recommendations in designing the length and arrangement of perforations to avoid these problems in future fracturing jobs are provided at the end of this paper.
Constrained-Equilibrium Modeling of Methane Oxidation in Air
Authors: Nicolas Ghassan , Janbozorgi Mohammad , Metghalchi Hameed
Published: May 2014

Rate-controlled constrained-equilibrium method has been further developed to model methane/air combustion. A set of constraints has been identified to predict the nonequilibrium evolution of the combustion process. The set predicts the ignition delay times of the corresponding detailed kinetic model to within 10% of accuracy over a wide range of initial temperatures (900 K–1200 K), initial pressures (1 atm–50 atm) and equivalence ratios (0.6–1.2). It also predicts the experimental shock tube ignition delay times favorably well. Direct integration of the rate equations for the constraint potentials has been employed. Once the values of the potentials are obtained, the concentration of all species can be calculated. The underlying detailed kinetic model involves 352 reactions among 60 H/O/N/C1-2 species, hence 60 rate equations, while the RCCE calculations involve 16 total constraints, thus 16 total rate equations. Nonetheless, the constrained-equilibrium concentrations of all 60 species are calculated at any time step subject to the 16 constraints.
Objectives and Constraints for Wind Turbine Optimization
Authors: Andrew Ning S. , Damiani Rick , Moriarty Patrick J.
Published: May 2014

Efficient extraction of wind energy is a complex, multidisciplinary process. This paper examines common objectives used in wind turbine optimization problems. The focus is not on the specific optimized designs, but rather on understanding when certain objectives and constraints are necessary, and what their limitations are. Maximizing annual energy production, or even using sequential aero/structural optimization, is shown to be significantly suboptimal compared to using integrated aero/structural metrics. Minimizing the ratio of turbine mass to annual energy production can be effective for fixed rotor diameter designs, as long as the tower mass is estimated carefully. For variable-diameter designs, the predicted optimal diameter may be misleading. This is because the mass of the tower is a large fraction of the total turbine mass, but the cost of the tower is a much smaller fraction of overall turbine costs. Minimizing the cost of energy is a much better metric, though high fidelity in the cost modeling is as important as high fidelity in the physics modeling. Furthermore, deterministic cost of energy minimization can be inadequate, given the stochastic nature of the wind and various uncertainties associated with physical processes and model choices. Optimization in the presence of uncertainty is necessary to create robust turbine designs.
Study the Combination of Photovoltaic Panels With Different Auxiliary Systems in Grid-Connected Condition
Authors: Sadeghi S. , Ameri M.
Published: May 2014

This study considers the effect of PV panel cost on the use of auxiliary power systems (APSs) in the hybrid power generation system for grid-connected condition. Using the auxiliary power systems along with the PV panels is not essential in grid-connected condition; furthermore, auxiliary power systems produce emission. Therefore, if using the APS is not economic, the use of them is not justifiable. If their use can be justified, a comparison should be made between different auxiliary systems in order to choose the best among. In this work, an evolutionary algorithm (Pareto envelope-based selection algorithm (PESA)) is used for the comparison of different auxiliary systems. In addition, the effect of seasonal and monthly changes of the panel angle is considered. Seasonal or monthly change of the panel angle can improve the PV panel productivity and decrease the annualized cost (ANC) of the power generation system. In addition, this study examines the economical effect of unit electricity power price on the power exchange rate of the hybrid system with grid utility.
Nonlinear Response of Wind Turbines Under Wind and Seismic Excitations With Soil–Structure Interaction
Authors: Sapountzakis Evangelos J. , Dikaros Ioannis C. , Kampitsis Andreas E. , Koroneou Angeliki D.
Published: May 2014

The objective of this paper is to present an efficient beam formulation based on the boundary element method (BEM), for the nonlinear dynamic analysis of wind turbine towers of variable cross section founded either on surface or on monopile foundation system. The whole structure may undergo moderately large displacements, taking into account the effect of soil–structure kinematic and inertia interaction. The tower is subjected to the combined action of arbitrarily distributed or concentrated transverse wind loading as well as to seismic excitation together with axial loading arising from the self-weight of the tower and the mechanical parts. The Blade element momentum theory is taken into consideration in order to produce the wind load time histories, while the site seismic response is obtained through one dimensional shear wave propagation analysis. The soil–surface foundation system is formulated as equivalent lateral and rotational springs, while the case of monopile system is treated as a prismatic beam on elastic foundation assigning the corresponding springs and dashpots along its length. An extensive case study is carried out on a wind turbine tower–foundation system employing the generated wind velocity time histories and recorded earthquake accelerograms, providing insight to several structural phenomena. The results of the proposed model are compared wherever possible with those obtained from a commercial finite elements software package, illustrating the validity and the efficiency of the developed method. From the obtained results, the strong influence of the nonlinear effects on the dynamic response of the wind turbine tower is verified.
A Level Set Method for the Construction of Boundary Conforming Voronoi Regions and Delaunay Triangulations Governed by a Spatial Distribution of Metrics
Authors: Keskin Ü. , Peiró J.
Published: May 2014

A Voronoi region can be interpreted as the shape achieved by a crystal that grows from a seed and stops growing when it reaches either the domain boundary or another crystal. This analogy is exploited here to devise a method for the generation of anisotropic boundary-conforming Voronoi regions for a set of points. This is achieved by simulating the propagation of crystals as evolving fronts modeled by a level set method. The techniques to detect the collision of fronts (crystals), formation of interfaces between seeds, and treatment of boundaries as additional (inner or outer) restricting seeds are described in detail. The generation of anisotropic Voronoi regions consistent with a user-prescribed Riemannian metric is achieved by re-interpreting the metric tensor in terms of the speed of propagation normal to the boundary of the crystal. This re-interpretation offers a better means of restricting metric fields for mesh generation.
Kinematic, Stiffness, and Dynamic Analyses of a Compliant Tensegrity Mechanism
Authors: Nouri Rahmat Abadi Bahman , Mehdi Shekarforoush S. M. , Mahzoon Mojtaba , Farid Mehrdad
Published: May 2014

The objective of this study is to present an analytical procedure for analysis of a compliant tensegrity mechanism focusing on its stiffness and dynamic characteristics. The screw calculus is used to derive the static equations and stiffness matrix of a full degree-of-freedom tensegrity mechanism, and the equations of motion are derived based on the principle of virtual work. Finally, some numerical examples are solved for the inverse dynamics of the mechanism.
Profile Synthesis of Planar Rotational–Translational Variable Joints
Authors: Slaboch Brian J. , Voglewede Philip A.
Published: May 2014

This paper presents an approach to the profile synthesis of planar, variable joints by combining higher variable joints. The possible permutations of planar, variable joints that change from a rotational to translational motion will be enumerated. A method will be provided to determine the profiles of variable joints, and a practical example will be presented to illustrate the proposed method.
Reconstruction Designs of the Lost Structures of the Antikythera Mechanism With Two Degrees of Freedom
Authors: Lin Jian-Liang , Yan Hong-Sen
Published: May 2014

The Antikythera mechanism is an ancient astronomical instrument with various functions to indicate the date of the Egyptian calendar, display the motions of celestial bodies, calculate astronomical periods, and predict eclipse events. However, the portions of the mechanism that have been excavated do not completely support its functions. In particular, the structures corresponding to the demonstration of solar and planetary motions have been lost. This paper presents a systematic reconstruction of design concepts for the lost structures with two degrees of freedom. According to the investigations of existing structure and other ancient astronomical instruments, design concepts with two degrees of freedom are generated, and three possible double-input conditions are identified. Based on a mechanism analysis, two types of reconstruction designs are developed: five-bar mechanisms with six joints and six-bar mechanisms with eight joints. Design constraints were determined in accordance with the historical literature and existing designs. Then, by applying the concepts of generalization and specialization, as well as the input conditions and manufacturing process, three, four, and seven feasible reconstruction designs are synthesized for the solar motion, inferior planetary motion, and superior planetary motion, respectively. In addition, relations for the teeth calculations are derived for detail designs.
Analysis of a Planar Tensegrity Mechanism for Ocean Wave Energy Harvesting
Authors: Vasquez Rafael E. , Crane, Carl D. , Correa Julio C.
Published: May 2014

Tensegrity systems have been used in several disciplines such as architecture, biology, aerospace, mechanics, and robotics during the last 50 years. However, just a few references in literature have stated the possibility of using such systems in ocean or energy-related applications. This work addresses the kinematic and dynamic analyses of a planar tensegrity mechanism for ocean wave energy harvesting. Ocean wave mechanics and the most important concepts related to fluid–structure interaction are presented. Then, a planar 3 degrees of freedom (3-dof) tensegrity mechanism, based on a morphology defined by Kenneth Snelson in 1960 which is known as “X-frame,” is proposed as connecting linkage to transmit wave-generated forces. A geometric approach is used to solve the forward and reverse displacement problems. The theory of screws is used to perform the forward and reverse velocity analyses of the device. The Lagrangian approach is used to deduce the equations of motion considering the interaction between the mechanism and ocean waves. The tensegrity-based mechanism is analyzed using a linear model of ocean waves and its energy harvesting capabilities are compared to a purely heaving device. Results show that the proposed tensegrity configuration allows to harvest 10% more energy than the traditional heaving mechanism used in several wave energy harvesting applications. Therefore, tensegrity systems could play an important role in the expansion of clean energy technologies that help the world's sustainable development.
Coupled and Self-Adaptive Under-Actuated Finger With a Novel S-Coupled and Secondly Self-Adaptive Mechanism
Authors: Li Guoxuan , Zhang Chi , Zhang Wenzeng , Sun Zhenguo , Chen Qiang
Published: May 2014

This paper presents a novel under-actuated (UA) finger with first coupled and secondly self-adaptive (COSA) grasping mode. COSA fingers can adaptively grasp objects with different sizes and shapes while its motions during grasping are anthropopathic. Until now there are two COSA mechanisms available and they are both direct parallel combinations of coupled mechanism and self-adaptive mechanism. These kind of direct combinations lead to complex mechanical structure and high power consumption. This paper proposes a novel single-route transmission mechanism for COSA grasping mode, S-coupled and directly self-adaptive (CDSA) mechanism for short. Compared with available COSA mechanisms, the S-CDSA mechanism has simpler structure and higher grasping force. Design of 2-joint S-CDSA finger is introduced in this paper. Force analysis for 2-joint S-CDSA finger is given. Furthermore, a 2-joint S-CDSA finger is manufactured. The force analysis and experimental results show that the novel S-CDSA mechanism is effective.
Reliable Robust Control Design for Uncertain Mechanical Systems
Authors: Sakthivel R. , Santra Srimanta , Mathiyalagan K. , Arunkumar A.
Published: May 2014

In this article, we consider the problem of reliable H∞ control for a class of uncertain mechanical systems with input time-varying delay and possible occurrence of actuator faults. In particular, we assume that linear fractional transformation (LFT) uncertainty formulations appear in the mass, damping, and stiffness matrices. The main objective is to design a state feedback reliable H∞ controller such that, for all admissible uncertainties as well as actuator failure cases, the resulting closed-loop system is robustly asymptotically stable while satisfying a prescribed H∞ performance constraint. By constructing an appropriate Lyapunov–Krasovskii functional (LKF) and using linear matrix inequality (LMI) approach, a new set of sufficient conditions are derived in terms of LMIs for the existence of robust reliable H∞ controller. Further, Schur complement and Jenson's integral inequality are used to substantially simplify the derivation in the main results. The obtained results are formulated in terms of LMIs which can be easily verified by the standard numerical softwares. Finally, numerical examples with simulation result are provided to illustrate the applicability and effectiveness of the proposed reliable H∞ control scheme. The numerical results reveal that the proposed theory significantly improves the upper bound of time delays and minimum feasible H∞ performance index over some existing works.