bluuebunny/crossref_metadata_2025 huggingface dataset:
SDF‐1 liposomes promote sustained cell proliferation in mouse diabetic wounds
Authors: Olekson Melissa A. Przyborowski , Faulknor Renea , Bandekar Amey , Sempkowski Michelle , Hsia Henry C. , Berthiaume François
Published: June 2015

Chronic skin wounds are a common complication of diabetes. When standard wound care fails to heal such wounds, a promising approach consists of using decellularized matrices and other porous scaffold materials to promote the restoration of skin. Proper revascularization is critical for the efficacy of such materials in regenerative medicine. Stromal cell‐derived factor‐1 (SDF‐1) is a chemokine known to play a key role for angiogenesis in ischemic tissues. Herein we developed nanosized SDF‐1 liposomes, which were then incorporated into decellularized dermis scaffolds used for skin wound healing applications. SDF‐1 peptide associated with liposomes with an efficiency of 80%, and liposomes were easily dispersed throughout the acellular dermis. Acellular dermis spiked with SDF‐1 liposomes exhibited more persistent cell proliferation in the dermis, especially in CD31+ areas, compared to acellular dermis spiked with free SDF‐1, which resulted in increased improved wound closure at day 21, and increased granulation tissue thickness at day 28. SDF‐1 liposomes may increase the performance of a variety of decellularized matrices used in tissue engineering.
The role of nitric oxide in passive leg movement‐induced vasodilatation with age: insight from alterations in femoral perfusion pressure
Authors: Groot H. Jonathan , Trinity Joel D. , Layec Gwenael , Rossman Matthew J. , Ives Stephen J. , Morgan David E. , Bledsoe Amber , Richardson Russell S.
Published: June 2015

Key points

The passive leg movement (PLM) model is a novel approach to assess vascular function.

Increasing femoral perfusion pressure (FPP) by moving from the supine to the upright‐seated posture augments the vasodilatory response to PLM in the young, with no effect in the old, but whether this augmented vasodilatation is nitric oxide (NO) dependent is unknown.

Using an intra‐arterial infusion of NG‐monomethyl‐L‐arginine (L‐NMMA) to inhibit nitric oxide synthase (NOS), the posture‐induced increases in the PLM responses in the young were nearly ablated, with no effect of NOS inhibition in the old.

Therefore, PLM in combination with alterations in posture can be used to determine changes in NO‐mediated vasodilatation with age, and thus, may be a clinically useful tool for assessing NO bioavailability across the human lifespan.

We sought to better understand the contribution of nitric oxide (NO) to passive leg movement (PLM)‐induced vasodilatation with age, with and without a posture‐induced increase in femoral perfusion pressure (FPP). PLM was performed in eight young (24 ± 1 years) and eight old (74 ± 3 years) healthy males, with and without NO synthase inhibition via intra‐arterial infusion of NG‐monomethyl‐L‐arginine (L‐NMMA) into the common femoral artery in both the supine and upright‐seated posture. Central and peripheral haemodynamic responses were determined second‐by‐second with finger photoplethysmography and Doppler ultrasound, respectively. PLM‐induced increases in heart rate, stroke volume, cardiac output and reductions in mean arterial pressure were similar between age groups and conditions. In the young, L‐NMMA attenuated the peak change in leg vascular conductance (ΔLVCpeak) in both the supine (control: 7.4 ± 0.9; L‐NMMA: 5.2 ± 1.1 ml min−1 mmHg−1, P < 0.05) and upright‐seated (control: 12.3 ± 2.0; L‐NMMA: 6.4 ± 1.0 ml min−1 mmHg−1, P < 0.05) posture, with no significant change in the old (supine control: 4.2 ± 1.3; supine L‐NMMA: 3.4 ± 0.8; upright‐seated control: 4.5 ± 0.8; upright‐seated L‐NMMA: 3.4 ± 0.8 ml min−1 mmHg−1, P > 0.05). Increased FPP augmented the ΔLVCpeak in the young control condition only (P < 0.05). In the upright‐seated posture, NOS inhibition attenuated the FPP‐induced augmentation of rapid vasodilatation in the young (control: 1.25 ± 0.23; L‐NMMA: 0.74 ± 0.11 ml min−1 mmHg−1 s−1; P < 0.05), but not the old (control: 0.37 ± 0.07; L‐NMMA: 0.25 ± 0.07 ml ml min−1 mmHg−1 s−1; P > 0.05). These data reveal that greater FPP increases the role of NO in PLM‐induced vasodilatation in the young, but not the old, due to reduced NO bioavailability with age. Therefore, PLM involving alterations in posture may be useful to determine changes in NO bioavailability with age.
Performance of today's dual energy CT and future multi energy CT in virtual non‐contrast imaging and in iodine quantification: A simulation study
Authors: Faby Sebastian , Kuchenbecker Stefan , Sawall Stefan , Simons David , Schlemmer Heinz‐Peter , Lell Michael , Kachelrieß Marc
Published: June 2015

Purpose:

To study the performance of different dual energy computed tomography (DECT) techniques, which are available today, and future multi energy CT (MECT) employing novel photon counting detectors in an image‐based material decomposition task.

Methods:

The material decomposition performance of different energy‐resolved CT acquisition techniques is assessed and compared in a simulation study of virtual non‐contrast imaging and iodine quantification. The material‐specific images are obtained via a statistically optimal image‐based material decomposition. A projection‐based maximum likelihood approach was used for comparison with the authors’ image‐based method. The different dedicated dual energy CT techniques are simulated employing realistic noise models and x‐ray spectra. The authors compare dual source DECT with fast kV switching DECT and the dual layer sandwich detector DECT approach. Subsequent scanning and a subtraction method are studied as well. Further, the authors benchmark future MECT with novel photon counting detectors in a dedicated DECT application against the performance of today's DECT using a realistic model. Additionally, possible dual source concepts employing photon counting detectors are studied.

Results:

The DECT comparison study shows that dual source DECT has the best performance, followed by the fast kV switching technique and the sandwich detector approach. Comparing DECT with future MECT, the authors found noticeable material image quality improvements for an ideal photon counting detector; however, a realistic detector model with multiple energy bins predicts a performance on the level of dual source DECT at 100 kV/Sn 140 kV. Employing photon counting detectors in dual source concepts can improve the performance again above the level of a single realistic photon counting detector and also above the level of dual source DECT.

Conclusions:

Substantial differences in the performance of today's DECT approaches were found for the application of virtual non‐contrast and iodine imaging. Future MECT with realistic photon counting detectors currently can only perform comparably to dual source DECT at 100 kV/Sn 140 kV. Dual source concepts with photon counting detectors could be a solution to this problem, promising a better performance.
Oral Presence of Carbohydrate and Caffeine in Chewing Gum: Independent and Combined Effects on Endurance Cycling Performance
Authors: Oberlin-Brown Katherine T. , Siegel Rodney , Kilding Andrew E. , Laursen Paul B.
Published: June 2015

The oral presence of carbohydrate (CHO) and caffeine (CAF) may independently enhance exercise performance, but their influence on performance during prolonged exercise is less known.

Aim:

To determine the independent and combined effects of CHO and CAF administered in chewing gum during a cycling time trial (TT) after prolonged exercise.

Method:

Eleven male cyclists (32.2 ± 7.5 y, 74.3 ± 6.8 kg, 60.2 ± 4.0 mL · kg–1 · min–1 V˙O2peak) performed 4 experimental trials consisting of 90-min constant-load cycling at 80% of their second ventilatory threshold (207 ± 30 W), followed immediately by a 20-km TT. Under double-blinded conditions, cyclists received placebo (PLA), CHO, CAF, or a combined CHO+CAF chewing gum at 0-, 5-, 10-, and 15-km points of the TT.

Results:

Overall TT performance was similar across experimental and PLA trials (%mean difference ± 90%CL 0.2% ± 2.0%, 0.4% ± 2.2%, 0.1% ± 1.8% for CHO, CAF, and CHO+CAF). Compared with PLA, mean power output tended to be higher in the first 2 quarters of the TT with CHO (1.6% ± 3.1% and 0.8% ± 2.0%) and was substantially improved in the last 2 quarters during CAF and CHO+CAF trials (4.2% ± 3.0% and 2.0% ± 1.8%). There were no differences in average heart rate (ES <0.2) and only small changes in blood glucose (ES 0.2), which were unrelated to performance. Blood lactate was substantially higher post-TT for CAF and CHO+CAF (ES >0.6).

Conclusion:

After prolonged constant-load cycling, the oral presence of CHO and CAF in chewing gum, independently or in combination, did not improve overall performance but did influence pacing.
Baby steps in gene therapy
Authors: Dalkara Deniz
Published: June 2015

Teaching the immune system tolerance to a missing protein in neonates improves safety and efficacy of gene replacement therapy.
Screen time
Authors: Bhatti Pamela
Published: June 2015

An interactive, tablet-based screening tool demonstrates predictive value for hearing loss in children.
Mixing it up
Authors: Bouvier Nicole M.
Published: June 2015

The genome reassortment among influenza A viruses that can lead to pandemics may be more common than we thought.
Elucidating the role of C9orf72 mutations in ALS
Authors: Statland Jeffrey
Published: June 2015

Conditional knockdown of
C9orf72
in mice does not cause loss of motor function or decrease survival, arguing against a loss-of-function role for C9orf72 in ALS.
Genes and lung cancer: Stop YAPping!
Authors: Thomas Anish
Published: June 2015

A highly penetrant germline mutation of
YAP1
oncogene predisposes to lung adenocarcinoma, and mutation carriers may benefit from increased surveillance.
Science Translational Medicine
Podcast: 24 June 2015
Authors: Agrawal Nishant , VanHook Annalisa
Published: June 2015

Nishant Agrawal talks about detecting tumor DNA in saliva and plasma of patients with head and neck cancers.
siRNA Screening Identifies the Host Hexokinase 2 (HK2) Gene as an Important Hypoxia-Inducible Transcription Factor 1 (HIF-1) Target Gene in Toxoplasma gondii-Infected Cells
Authors: Menendez Matthew T. , Teygong Crystal , Wade Kristin , Florimond Celia , Blader Ira J.
Published: June 2015

Although it is established that oxygen availability regulates cellular metabolism and growth, little is known regarding how intracellular pathogens use host factors to grow at physiological oxygen levels. Therefore, large-scale human small interfering RNA screening was performed to identify host genes important for growth of the intracellular protozoan parasite
Toxoplasma gondii
at tissue oxygen tensions. Among the genes identified by this screen, we focused on the hexokinase 2 (HK2) gene because its expression is regulated by hypoxia-inducible transcription factor 1 (HIF-1), which is important for
Toxoplasma
growth.
Toxoplasma
increases host HK2 transcript and protein levels in a HIF-1-dependent manner. In addition, parasite growth at 3% oxygen is restored in HIF-1-deficient cells transfected with HK2 expression plasmids. Both HIF-1 activation and HK2 expression were accompanied by increases in host glycolytic flux, suggesting that enhanced HK2 expression in parasite-infected cells is functionally significant. Parasite dependence on host HK2 and HIF-1 expression is not restricted to transformed cell lines, as both are required for parasite growth in nontransformed C2C12 myoblasts and HK2 is upregulated
in vivo
following infection. While HK2 is normally associated with the cytoplasmic face of the outer mitochondrial membrane at physiological O
2
levels, HK2 relocalizes to the host cytoplasm following infection, a process that is required for parasite growth at 3% oxygen. Taken together, our findings show that HIF-1-dependent expression and relocalization of HK2 represent a novel mechanism by which
Toxoplasma
establishes its replicative niche at tissue oxygen tensions.

IMPORTANCE
Little is known regarding how the host cell contributes to the survival of the intracellular parasite
Toxoplasma gondii
at oxygen levels that mimic those found in tissues. Our previous work showed that
Toxoplasma
activates the expression of an oxygen-regulated transcription factor that is required for growth. Here, we report that
Toxoplasma
regulates the abundance and activity of a key host metabolic enzyme, hexokinase 2, by activating HIF-1 and by promoting dissociation of hexokinase 2 from the mitochondrial membrane. Collectively, our data reveal HIF-1/hexokinase 2 as a novel target for an intracellular pathogen that acts by reprograming the host cell's metabolism to create an environment conducive for parasite replication at physiological oxygen levels.
Functional Analysis of the Human Antibody Response to Meningococcal Factor H Binding Protein
Authors: Beernink Peter T. , Giuntini Serena , Costa Isabella , Lucas Alexander H. , Granoff Dan M.
Published: June 2015

Two licensed serogroup B meningococcal vaccines contain factor H binding protein (FHbp). The antigen specifically binds human FH, which downregulates complement. In wild-type mice whose mouse FH does not bind to FHbp vaccines, the serum anti-FHbp antibody response inhibited binding of human FH to FHbp. The inhibition was important for eliciting broad anti-FHbp serum bactericidal activity. In human FH transgenic mice and some nonhuman primates, FHbp was able to form a complex with FH and FHbp vaccination elicited anti-FHbp antibodies that did not inhibit FH binding. To investigate the human anti-FHbp repertoire, we cloned immunoglobulin heavy- and light-chain-variable-region genes of individual B cells from three adults immunized with FHbp vaccines and generated 10 sequence-distinct native anti-FHbp antibody fragments (Fabs). All 10 Fabs bound to live meningococci; only 1 slightly inhibited binding of human FH, while 4 enhanced FH binding. Affinity-purified anti-FHbp antibody from serum of a fourth immunized adult also enhanced binding of human FH to live meningococcal bacteria. Despite the bound FH, the affinity-purified serum anti-FHbp antibodies elicited human complement-mediated bactericidal activity that was amplified by the alternative pathway. The lack of FH inhibition by the human anti-FHbp Fabs and serum antibodies suggests that binding of human FH to the vaccine antigen skews the anti-FHbp antibody repertoire to epitopes outside the FH-binding site. Mutant FHbp vaccines with decreased FH binding may represent a means to redirect the human antibody repertoire to epitopes within the FH binding site, which can inhibit FH binding and, potentially, increase safety and protective activity.

IMPORTANCETwo meningococcal vaccines contain factor H binding protein (FHbp). Immunized mice whose mouse factor H (FH) does not bind to FHbp develop serum anti-FHbp antibodies that block binding of human FH to the bacteria. With less bound FH, the bacteria become more susceptible to complement killing. To investigate human responses, we isolated 10 recombinant anti-FHbp antibody fragments (Fabs) from immune cells of three immunized adults. One slightly inhibited binding of FH to the bacteria, and four enhanced FH binding. Purified serum anti-FHbp antibodies from a fourth immunized adult also enhanced FH binding. Although bound FH would be expected to block the alternative pathway, the human anti-FHbp antibodies retained bactericidal activity and the ability to activate the alternative pathway. Mutant FHbp vaccines with decreased binding to human FH may redirect the human antibody repertoire to epitopes within the FH binding site that inhibit FH binding, which are expected to increase protective activity.
Effects of Transcutaneous Electrical Nerve Stimulation on Rats with the Third Lumbar Vertebrae Transverse Process Syndrome
Authors: Li Huan , Shang Xiao-Jun , Dong Qi-Rong
Published: June 2015

Objective

To investigate the analgesic and anti-inflammatory effects of transcutaneous electrical nerve stimulation (TENS) at local or distant acupuncture points in a rat model of the third lumbar vertebrae transverse process syndrome.

Methods

Forty Sprague–Dawley rats were randomly divided into control, model, model plus local acupuncture point stimulation at BL23 (model+LAS) and model plus distant acupuncture point stimulation at ST36 (model+DAS) groups. All rats except controls underwent surgical third lumbar vertebrae transverse process syndrome modelling on day 2. Thereafter, rats in the model+LAS and model+DAS groups were treated daily with TENS for a total of six treatments (2/100 Hz, 30 min/day) from day 16 to day 29. Thermal pain thresholds were measured once a week during treatment and were continued until day 57, when local muscle tissue was sampled for RT-PCR and histopathological examination after haematoxylin and eosin staining. mRNA expression of interleukin-1 β (IL-1β), tumour necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) was determined.

Results

Thermal pain thresholds of all model rats decreased relative to the control group. Both LAS and DAS significantly increased the thermal pain threshold at all but one point during the treatment period. Histopathological assessment revealed that the local muscle tissues around the third lumbar vertebrae transverse process recovered to some degree in both the model+LAS and model+DAS groups; however, LAS appeared to have a greater effect. mRNA expression of IL-1β, TNF-α and iNOS in the local muscle tissues was increased after modelling and attenuated in both model+LAS and model+DAS groups. The beneficial effect was greater after LAS than after DAS.

Conclusions

TENS at both local (BL23) and distant (ST36) acupuncture points had a pain-relieving effect in rats with the third lumbar vertebrae transverse process syndrome, and LAS appeared to have greater anti-inflammatory and analgesic effects than DAS.

Trial Registration Number

09073.
Isokinetic muscle strength and readiness to return to sport following anterior cruciate ligament reconstruction: is there an association? A systematic review and a protocol recommendation
Authors: Undheim Marit Baste , Cosgrave Ciaran , King Enda , Strike Siobhán , Marshall Brendan , Falvey Éanna , Franklyn-Miller Andrew
Published: June 2015

Introduction

Following anterior cruciate ligament reconstruction (ACLR), strength is a key variable in regaining full function of the knee. Isokinetic strength is commonly used as part of the return to sport (RTS) criteria.

Aim

We systematically reviewed the isokinetic strength evaluation protocols that are currently being used following ACLR. A secondary aim was to suggest an isokinetic protocol that could meet RTS criteria.

Method

Articles were searched using ScienceDirect, PubMed and Sage Journals Online, combined with cross-checked reference lists of the publications. Protocol data and outcome measurements and RTS criteria were extracted from each article included in the review.

Results

39 studies met the inclusion criteria and reported their isokinetic strength evaluation protocol following ACLR. The variables that were most commonly used were concentric/concentric mode of contraction (31 studies), angular velocity of 60°/s (29 studies), 3–5 repetitions (24 studies), range of motion of 0–90° (6 studies), and using gravity correction (9 studies). 8 studies reported strength limb symmetry index scores as part of their RTS criteria.

Conclusions

There was no standardised isokinetic protocol following ACLR; isokinetic strength measures have not been validated as useful predictors of successful RTS. We propose a standard protocol to allow consistency of testing and accurate comparison of future research.
Hamstring injuries: prevention and treatment—an update
Authors: Brukner Peter
Published: June 2015

Despite increased knowledge of hamstring muscle injuries, the incidence has not diminished. We now know that not all hamstring injuries are the same and that certain types of injuries require prolonged rehabilitation and return to play. The slow stretch type of injury and injuries involving the central tendon both require longer times to return to play. A number of factors have been proposed as being indicators of time taken to return to play, but the evidence for these is conflicting. Recurrence rates remain high and it is now thought that strength deficits may be an important factor. Strengthening exercise should be performed with the hamstrings in a lengthened position. There is conflicting evidence regarding the efficacy of platelet-rich plasma injection in the treatment of hamstring injuries so at this stage we cannot advise their use. Various tests have been proposed as predictors of hamstring injury and the use of the Nordboard is an interesting addition to the testing process. Prevention of these injuries is the ultimate aim and there is increasing evidence that Nordic hamstring exercises are effective in reducing the incidence.
Perceptions of medical students towards antibiotic prescribing for upper respiratory tract infections in Saudi Arabia
Authors: Harakeh Steve , Almatrafi Musab , Ungapen Haifa , Hammad Rotana , Olayan Feras , Hakim Reema , Ayoub Mohammed , Bakhsh Noura , Almasaudi Saad B , Barbour Elie , Bahijri Suhad , Azhar Esam , Damanhouri Ghazi , Qari Yousef , Kumosani Taha , Harakeh Zeena , Ahmad Muhammad S , Cals JochenW L
Published: June 2015

Introduction

This survey evaluates knowledge, attitudes and practices of medical students towards use of antibiotics for upper respiratory infections (URTIs).

Methodology

Cross-sectional questionnaire study among 1042 randomly selected medical students in Saudi Arabia.

Results

Respondents were mostly Saudis (97.5%), had previous knowledge of antibiotics (99.7%) and their usage (98.3%) against bacterial infections (93.7%). 18.1% thought that they could be used for viral infections. Nearly all students (97.2%) used antibiotics themselves during the previous year and self-medication without a prescription was high at 49% of cases. Most antibiotics were taken for URTI symptoms (61.8%). Female medical students had better knowledge on antibiotic effectiveness against bacteria and viruses, and overall knowledge increased with study year. Health seeking behaviour rates for symptoms of RTI and associated estimated necessity for antibiotics varied but were highest for cough with yellow/green phlegm.

Conclusions

The depth of knowledge that healthcare professionals have in relation to the proper use of antibiotics is essential in spreading the right message within communities. This is the first large study among medical students in Saudi Arabia, shedding important light on areas for improvement in the medical curriculum as well as antibiotic practices of medical students themselves.
Serial sampling of copeptin levels improves diagnosis and risk stratification in patients presenting with chest pain: results from the CHOPIN trial
Authors: Marston Nicholas A , Shah Kevin S , Mueller Christian , Neath Sean-Xavier , Christenson Robert H , McCord James , Nowak Richard M , Daniels Lori B , Hollander Judd E , Apple Fred , Nagurney John , Schreiber Donald , deFilippi Christopher , Diercks Deborah , Limkakeng Alexander , Anand Inder S , Wu Alan HB , Jaffe Allan S , Peacock W Frank , Maisel Alan S
Published: June 2015

Background

Copeptin has demonstrated a role in early rule out for acute myocardial infarction (AMI) in combination with a negative troponin. However, management of patients with chest pain with a positive copeptin in the setting of a negative troponin is unclear.

Methods

The multicentre CHOPIN trial enrolled 2071 patients with acute chest pain. Of these, 476 subjects with an initial negative troponin but an elevated copeptin (>14 pmol/L) were included in this study. Copeptin and troponin levels were rechecked at 2 h and the final diagnosis of AMI was made by two independent, blinded cardiologists. Follow-up at 30 days was obtained for major adverse cardiac events (MACEs), including death, AMI and urgent revascularisation.

Results

Of the 476 patients analysed, 365 (76.7%) had a persistently elevated copeptin at 2 h and 111 patients (23.3%) had a copeptin that fell below the cut-off of 14 pmol/L. When the second copeptin was elevated there were 18 AMIs (4.9%) compared with 0 (0%) when the second copeptin was negative (p=0.017), yielding a negative predictive value of 100% (95% CI 96.7% to 100%). On 30-day follow-up there were 36 MACEs (9.9%) in the positive second copeptin group and 2 (1.8%) MACEs in the negative second copeptin group (p=0.006).

Conclusions

Patients with chest pain with an initial negative troponin but positive copeptin are common and carry an intermediate risk of AMI. A second copeptin drawn 2 h after presentation may help risk stratify and potentially rule out AMI in this cohort.
Combining metformin therapy with caloric restriction for the management of type 2 diabetes and nonalcoholic fatty liver disease in obese rats
Authors: Linden Melissa A. , Lopez Kristi T. , Fletcher Justin A. , Morris E. Matthew , Meers Grace M. , Siddique Sameer , Laughlin M. Harold , Sowers James R. , Thyfault John P. , Ibdah Jamal A. , Rector R. Scott
Published: June 2015

Weight loss is recommended for patients with nonalcoholic fatty liver disease (NAFLD), while metformin may lower liver enzymes in type 2 diabetics. Yet, the efficacy of the combination of weight loss and metformin in the treatment of NAFLD is unclear. We assessed the effects of metformin, caloric restriction, and their combination on NAFLD in diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Male OLETF rats (age 20 weeks; n = 6–8 per group) were fed ad libitum (AL), given metformin (300 mg·kg−1·day−1; Met), calorically restricted (70% of AL; CR), or calorically restricted and given metformin (CR+Met) for 12 weeks. Met lowered adiposity compared with AL but not to the same magnitude as CR or CR+Met (p < 0.05). Although only CR improved fasting insulin and glucose, the combination of CR+Met was needed to improve post-challenge glucose tolerance. All treatments lowered hepatic triglycerides, but further improvements were observed in the CR groups (p < 0.05, Met vs. CR or CR+Met) and a further reduction in serum alanine aminotransferases was observed in CR+Met rats. CR lowered markers of hepatic de novo lipogenesis (fatty acid synthase, acetyl-CoA carboxylase (ACC), and stearoyl-CoA desaturase-1 (SCD-1)) and increased hepatic mitochondrial activity (palmitate oxidation and β-hydroxyacyl CoA dehydrogenase (β-HAD) activity). Changes were enhanced in the CR+Met group for ACC, SCD-1, β-HAD, and the mitophagy marker BNIP3. Met decreased total hepatic mTOR content and inhibited mTOR complex 1, which may have contributed to Met-induced reductions in de novo lipogenesis. These findings in the OLETF rat suggest that the combination of caloric restriction and metformin may provide a more optimal approach than either treatment alone in the management of type 2 diabetes and NAFLD.
The making of a Barr body: the mosaic of factors that eXIST on the mammalian inactive X chromosome
Authors: Dixon-McDougall Thomas , Brown Carolyn
Published: June 2015

During X-chromosome inactivation (XCI), nearly an entire X chromosome is permanently silenced and converted into a Barr body, providing dosage compensation for eutherians between the sexes. XCI is facilitated by the upregulation of the long non-coding RNA gene, XIST, which coats its chromosome of origin, recruits heterochromatin factors, and silences gene expression. During XCI, at least two distinct types of heterochromatin are established, and in this review we discuss the enrichment of facultative heterochromatin marks such as H3K27me3, H2AK119ub, and macroH2A as well as pericentric heterochromatin marks such as HP1, H3K9me3, and H4K20me3. The extremely stable maintenance of silencing is a product of reinforcing interactions within and between these domains. This paper “Xplores” the current knowledge of the pathways involved in XCI, how the pathways interact, and the gaps in our understanding that need to be filled.
Life Cycle of Salmincola californiensis (Dana 1852) (Copepoda: Lernaeopodidae)
Authors: Kabata Z. , Cousens B.
Published: June 2015

A description is given of the life cycle of Salmincola californiensis (Copepoda: Lernaeopodidae), studied by continuous observation of developing parasites and by intermittent examination of infected sockeye salmon (Oncorhynchus nerka). The cycle consists of six stages: copepodid (free-swimming), four chalimus stages (attached by second maxillae to frontal filament), and adult (attached by bulla). The copepodid settles on the fish and uncoils its frontal filament. Each successive chalimus stage reattaches the filament during moulting, but chalimus IV breaks off, searches for the site of final attachment, and excavates an implantation cavity for the bulla. The male cycle is similar but its chalimus IV is of shorter duration and soon moults into the male adult, actively searching for the female. Morphology of all stages is described in detail. Some comments are made on life cycles in Caligoida.
Delay-Differential Equation Models for Fisheries
Authors: Walter Gilbert G.
Published: June 2015

Two new "simple" fishery models based on delay-differential equations are introduced and compared to three currently used differential equation models. These new models can account for reproductive lag and allow oscillatory behavior of population biomass, but require only catch and effort data for their application. Equilibrium levels are calculated for both models and examples of various types of growth curves are given. Levels of fishing effort which maximize yield are calculated and found in one case to depend on the previous population and in the other to be constant.
Observations on the Cestode Eubothrium salvelini in Juvenile Sockeye Salmon (Oncorhynchus nerka) at Babine Lake, British Columbia
Authors: Smith H. D.
Published: June 2015

Infection incidence among 15 brood years of smolts in the period 1952–71 was estimated from smolt and underyearling samples, and among late run fish from the main part of Babine Lake ranged from 6 to 45% (average 26%). In early run fish from the North Arm–Nilkitkwa area it ranged from 5 to 46% (average 22%) in 10 years during 1958–71.Infection intensity changed substantially during 1967; but about one fish in eight, or 200,000 individuals in the early run, carried parasite loads [Formula: see text] of fish weight. Mature E. salvelini (Schrank 1790) averaged 32 mg in weight and 34 mm in length during a period of high incidence and intensity of infection in 1967.Although no proof was found of direct mortality caused by E. salvelini, indirect effects such as inferior growth, poor swimming performance, or aberrant behavior due to large cestode loads may increase host susceptibility to death from other causes.Changes in relative abundance of the zooplankton intermediate host, and midsummer shifts in feeding preferences of young sockeye likely account for increasing infection incidence in June and July, and stable incidence thereafter.
Chemical Basis for Homing of Atlantic Salmon (Salmo salar) to a Hatchery
Authors: Sutterlin A. M. , Gray R.
Published: June 2015

Based on recoveries from traps situated at a hydroelectric dam and a hatchery 1500 m downstream, the return location of hatchery reared and wild Atlantic salmon is examined. During the fall runs of 1971 and 1972, 97% of ascending wild salmon returned to the dam; only 3% were recovered at the hatchery. Despite the fact that the hatchery discharge contributed only 1/1000th of the river’s flow, 67% of the hatchery-reared fish returned to the hatchery and 33% to the dam.Tank tests demonstrated a clear-cut preference by hatchery adults for diluted hatchery effluent vs. river water. Wild fish showed no preference to either water. Well water, a component of hatchery effluent, was avoided by both hatchery and wild fish. Addition of CuSO4 to preferred water altered its effectiveness.
Scolecobasidium humicola, a Fungal Pathogen of Fish
Authors: Ross A. J. , Yasutake W. T.
Published: June 2015

Scolecobasidium humicola, a previously undescribed fungal pathogen of fish was isolated from coho salmon (Oncorhynchus kisutch). In natural infections the kidney was the organ most affected. The disease was difficult to transmit experimentally and appeared to be only weakly contagious.
Some Chemical Signals in the Spawning Behavior of Rainbow Trout (Salmo gairdneri)
Authors: Newcombe C. , Hartman G.
Published: June 2015

In a two-choice maze ripe rainbow trout (Salmo gairdneri) of both sexes showed positive responses to chemical (probably olfactory) information. The possibility that visual or auditory stimuli influenced choice of channel in the maze was ruled out. Both males and females were strongly attracted to water taken from behind fish that were spawning and weakly attracted to the holding water of ripe fish that were not spawning. Brief speculation is offered about the role of chemical stimuli in the behavior of prespawning and spawning trout.
Relation Between Simple Dynamic Pool and Surplus Production Models for Yield from a Fishery
Authors: Jensen A. L.
Published: June 2015

Dynamic pool models without self-regenerating properties are continuous age models, and surplus production models are continuous time models. Self-regenerating dynamic pool models are continuous age-discrete generation models and, also, discrete time-discrete age models. In a steady state specification of the regulatory function and direct estimation of biomass results in the surplus production model. Estimation of biomass by specifying the functions with respect to age for size of a cohort and individual weight and application of the coefficient of fishing mortality result in the dynamic pool model. A third approach, not applied in fisheries, is to specify the regulatory function and functions with respect to age of cohort size and individual growth in weight. In a steady state all methods for calculating yield give the same results if the functions specified are realistic. Specification of the functions requires that many assumptions be made. The dynamic pool model may be more accurate than the surplus production model because the regulatory function may be more difficult to determine than the functions with respect to age of cohort size and growth in individual weight.
Age, Growth, and Maturity of Bottlenosed Dolphin (Tursiops truncatus) from Northeast Florida
Authors: Sergeant D. E. , Caldwell David K. , Caldwell Melba C.
Published: June 2015

It is confirmed that one growth layer consisting of one opaque and one translucent zone is laid down annually in the dentine of the teeth of bottlenosed dolphin (Tursiops truncatus), allowing absolute age determination, although the seasonal sequence of dentine deposition is not yet clear. On this basis females from northeast Florida were found to mature at about 12 years and males at 13 years, both sexes living to about 25 years of age. Females accumulated up to 14 corpora albicantia in the ovaries, indicating an accumulation rate of about one per annum. Birth occurred at 100-cm length. Males and females matured at about 245- and 235-cm length, respectively, and attained asymptotic lengths of about 270 and 250 cm.
Remarks on the Einstein–Euler-Entropy system
Authors: Disconzi Marcelo M.
Published: June 2015

We prove short-time existence for the Einstein–Euler-Entropy system for non-isentropic fluids with data in uniformly local Sobolev spaces. The cases of compact as well as non-compact Cauchy surfaces are covered. The method employed uses a Lagrangian description of the fluid flow which is based on techniques developed by Friedrich, hence providing a completely different proof of earlier results of Choquet-Bruhat and Lichnerowicz. This new proof is specially suited for applications to self-gravitating fluid bodies. Along the way, we review some basic definitions and ideas, giving thus a relatively self-contained exposition that also serves as an introduction to many aspects of the problem.
Covariant asymmetric wave packet for a field-theoretical description of neutrino oscillations
Authors: Naumov Vadim A. , Shkirmanov Dmitry S.
Published: June 2015

We consider a class of models for the relativistic covariant wave packets (WPs) which can be used as asymptotically free in and out states in the quantum field theoretical formalisms for description of the neutrino flavor oscillation phenomenon. We demonstrate that the new “asymmetric” wave packet (AWP) is an appropriate alternative to the more conventional “symmetric” WPs, like the so-called relativistic Gaussian packet (RGP) widely used in the quantum field theory (QFT)-based approaches to neutrino oscillations. We show that RGP is not a particular case of AWP, although many properties of these models are almost identical in the quasistable regime. We discuss some features of AWP distinguishing it from RGP.
h-Hash: A Hash Index Structure for Flash-Based Solid State Drives
Authors: Kim Bo-Kyeong , Lee Sang-Won , Lee Dong-Ho
Published: June 2015

Flash-based solid state drives (SSDs) have been widely used as storage medium because of their fast access speed, high reliability and low power consumption. In spite of these advantages, they inherit distinct characteristics such as no in-place updates, asymmetric operation speed and unit because they consist of NAND flash memories. Therefore, a disk-based hash index structure may result in severe performance degradation if it is directly deployed on a NAND flash memory-based storage system. In this paper, we propose a new hybrid hash index structure for flash-based SSDs. It delays and reduces the split operations which cause slow block erasure and additional read and write operations by exploiting overflow buckets according to the ratio of updates and deletions. Through various performance evaluations, we show the superiority of our proposed index structure by comparing it to other hash index structures for flash-based SSDs.
Deciding conjugacy in sylvester monoids and other homogeneous monoids
Authors: Cain Alan J. , Malheiro António
Published: June 2015

We give a combinatorial characterization of conjugacy in the sylvester monoid, showing that conjugacy is decidable for this monoid. We then prove that conjugacy is undecidable in general for homogeneous monoids and even for multihomogeneous monoids.
Newtonian wormholes with spherical symmetry and tidal forces on test particles
Authors: Luz Paulo , Lemos José P. S.
Published: June 2015

A spherically symmetric wormhole in Newtonian gravitation in curved space, enhanced with a connection between the mass density and the Ricci scalar, is presented. The wormhole, consisting of two connected asymptotically flat regions, inhabits a spherically symmetric curved space. The gravitational potential, gravitational field and the pressure that supports the fluid that permeates the Newtonian wormhole are computed. Particle dynamics and tidal effects in this geometry are studied. The possibility of having Newtonian black holes in this theory is sketched.
A DISCUSSION ON FRACTAL MODELS FOR TRANSPORT PHYSICS OF POROUS MEDIA
Authors: XU PENG
Published: June 2015

Fractal model provides an alternative and useful means for studying the transport phenomenon in porous media and analyzing the macroscopic transport properties of porous media, as fractal geometry can successfully characterize disordered and heterogeneous geometrical microstructures of porous media on multi scales. Recently, fractal models on porous media have attracted increasing interests from many different disciplines. In this mini-review paper, a review on fractal models for number-size distribution in porous media is made, and a unified fractal model to characterize pore and particle size distributions is proposed according to the statistical fractal property of the complex microstructure in porous media. Using the fractal scaling laws for pore and fracture size distributions, a fractal capillary bundle model and a fractal tree-like network model are presented and summarized for homogenous and fractured porous media, respectively. And the applications of the fractal capillary bundle model and fractal tree-like network model for analysis of transport physics in porous media are also reviewed.
Organo Modified Multi-Walled Carbon Nanotube Reinforced Pyridine Core Polybenzoxazine (MWCNT/PBZ) Nanocomposites
Authors: Gunasekaran S. G. , Rajakumar K. , Dharmendirakumar M.
Published: June 2015

A new series of multi-walled carbon nanotube reinforced polybenzoxazine (MWCNT/PBZ) nanocomposites was successfully designed and developed. Three different maleimido terminal benzoxazine monomers (MI-BZs) were synthesized using N-(4-hydroxyphenyl) maleimide (HPM) and formaldehyde solution through Mannich condensation reaction and were characterized by FT-IR and NMR spectroscopy. Varying weight percentages (0 wt.%, 0.5 wt.%, 1.0 wt.% and 1.5 wt.%) of glycidyl-MWCNT were then incorporated into benzoxazine matrices to prepare MWCNT/PBZ nanocomposites. The nanocomposites having higher weight percentage of MWCNT were found to possess excellent thermal properties than those of neat PBZs. The developed nanocomposites exhibited better flame retardancy and higher dielectric constant. The optical properties ascertained from the UV-Vis absorption bands at the region of 300–350 nm and strong fluorescent emissions were observed in the wavelength range of 300–550 nm from Photoluminescence analysis. The intensity of characteristic diffraction peaks corresponding to g-MWCNT confirmed the reinforcement of MWCNT in the benzoxazine matrices, which indicated the successful formation of nanocomposites. The morphological studies ascertain the compatibility and uniform dispersion of MWCNT in the PBZ network.
On the Usage of Tetrahedral Background Cells in Nodal Integration of RPIM for 3D Elasto-Static Problems
Authors: Yavuz M. M. , Kanber B.
Published: June 2015

In this paper, tetrahedral background cells are used in nodal integration of radial point interpolation method (RPIM). The nodal integration is based on Taylor series terms and it is originally applied for the solutions of 2D problems in literature. Therefore, in this study, it is attempted that the tetrahedral integration cells are used in the solution of 3D elasto-static problems. The accuracy is seriously affected by order of Taylor series terms and it is investigated up to fifth order. A methodology is developed for prevention of negative volumes and calculation problems in subdivision of integration cells for each node. Three different case studies are solved with different support domain sizes and shape parameters. The best accuracy is achieved with fourth-order Taylor terms in nodal integration radial point interpolation method (NI-RPIM). [Formula: see text]-value of 3.00 and [Formula: see text] value of 1.03 in radial basis functions give good results in all cases.
Remarks on infinitesimal symmetries of geometrical structures of the classical phase space of general relativistic test particle
Authors: Janyška Josef
Published: June 2015

The phase space of general relativistic test particle is defined as the 1-jet space of motions. A Lorentzian metric and an electromagnetic field define the joined almost-cosymplectic-contact structure on the odd-dimensional phase space. In this paper, we study infinitesimal symmetries (ISs) of this phase structure. We prove that there are no hidden ISs.
Numerical Study of Flow Patterns in a Tandem Array Cylinder System
Authors: Hsu Li-Chieh , Ye Jian-Zhi
Published: June 2015

The spectral element method, a direct numerical technique, is used to study the behavior of flow past two cylinders in tandem array. A control cylinder is employed in front of the main cylinder to study the drag reduction performance and flow patterns. Three major flow patterns are found, including single cylinder vortex shedding, two cylinders vortex shedding and suppression. The flow patterns are affected by the distance between two cylinders, Reynolds number and the diameter ratios of cylinders. In a bistable regime, when there is a critical distance between cylinders, drag is reduced dramatically.
Dynamic Fracture and Dissipation Behaviors of Concrete at the Mesoscale
Authors: Lammi Christopher J. , Li Hongwei , McDowell David L. , Zhou Min
Published: June 2015

Dynamic compaction and fracture of concrete is simulated at the mesoscale. Calculations are carried out under conditions of nominally uniaxial stress and uniaxial strain at a strain rate of 5000 s-1, allowing the effect of confinement, or stress triaxiality, on the response to be analyzed. A series of mesostructures, each member containing between 0–40% quartz aggregate and 0–5% pores by volume, is randomly generated to investigate the effect of mesostructure. The analysis focuses on load-carrying capacity and energy dissipation. Fracture within bulk phases and along interfaces in the structures is modeled using the cohesive finite element method. Dissipation through inelastic flow, fracture, and friction are separately tracked and quantified. Calculated results show that triaxiality has a strong influence on the dominant mode of energy dissipation and the volume fractions of aggregate and pores significantly influence the load-carrying capacity and energy dissipation capabilities of the materials. The framework and data presented can be used to support the design of materials with optimized trade-offs between competing performance metrics during dynamic loading.
Effect of Projectile Geometry on the Deformation Behavior of Kevlar Composite Armors Under Ballistic Impact
Authors: Bandaru Aswani Kumar , Ahmad Suhail
Published: June 2015

A failure model based on the three-dimensional strains in a composite layer with improved progressive damage modeling has been implemented to predict the deformation behavior of composite armors subjected to ballistic impact. The present model comprises mainly of two parts. First, quadratic strain based failure criteria are presented to predict the initiation of failure modes. Second, the post damage softening behavior and degradation of the material stiffness is measured by damage evolution law. The model has been implemented within ABAQUS/Explicit as a user defined subroutine VUMAT. The validity of the model has been carried out by performing computational analysis of different composite armor materials such as Kevlar 29 and Kevlar 129 impacting with cylindrical-hemispherical nosed and 120° conical projectiles. It transpires that the predictions from the present model are in good agreement with the experimental and numerical observations available in the literature in terms of back face signature (BFS) for both the targets and projectiles. Further, the model has been implemented to study the effect of projectile geometry on the velocity time histories of the projectile, residual velocity and ballistic limit velocity. BFS values showed good agreement for conical projectile while for hemispherical projectile it is slightly low. The combination of Kevlar 129 armor and hemispherical projectile shows higher ballistic limit compared to that of the other combinations.