bluuebunny/crossref_metadata_2025 huggingface dataset:
Al2O3 Particle Size Effect on Reinforced Copper Alloys: An Experimental Study
Authors: El‐Hadek M. A. , Kaytbay S.
Published: October 2008

Abstract:  Bonding between dissimilar metallic (copper) and non‐metallic particles (Al2O3) was successfully achieved. The mechanical properties of the copper composite nano‐structure with different Al2O3 particle sizes ranging from 100 nm to 20 μm were investigated. The alloys were prepared by using electro‐less precipitation and particle metallurgy technique at three different sintered temperatures, 900, 950 and 1000 °C. The chemical composition of composites were 85 atomic % Cu and 15 atomic % Al2O3, of which commercially available Al2O3 particles with a purity of 99.5% were used. The microstructure, hardness and compressive stress–strain behaviours were determined. A pin‐on‐disc system was used to study wear. Electrical resistivity was also measured.
Advances in Tunneled Central Venous Catheters for Dialysis: Design and Performance
Authors: Ash Stephen R.
Published: October 2008

Over 70% of patients initiating chronic hemodialysis in the United States have a tunneled central venous catheter (CVC) for dialysis as their first blood access device. Tunneled CVC have requirements that are unparalleled by other access devices: high blood flow rates at moderate pressure drops without obstruction, minimal trauma to the vein, resistance to occlusion by fibrous sheathing, prevention of infection, avoidance of clotting, biocompatibility, avoidance of lumen collapse and kinking and breaks, resistance to antiseptic agents, placement with minimal trauma, and radiopaque appearance on X‐ray. This publication reviews the numerous designs for tunneled CVC and evaluates the advantages and disadvantages of each design. A catheter that self‐centers in the superior vena cava (Centros™) is described, along with early clinical results. Current challenges and future directions for tunneled CVC for dialysis are discussed, included means to diminish catheter‐related infections, catheter tip clotting, fibrous sheathing, central venous stenosis, and external component bulk.
Hemodialysis Central Venous Catheter Dysfunction
Authors: Chan Micah R.
Published: October 2008

Despite aggressive efforts to increase autogenous fistula prevalence, catheters remain an essential access modality to a large percentage of the hemodialysis population. Central venous catheter dysfunction, which includes catheter‐related bacteremia and thrombotic occlusion, comprises the majority of complications which affect dialysis adequacy, patient quality of life, patient survival, and the economics of health care. This review provides a comprehensive overview of hemodialysis central venous catheter dysfunction, its epidemiology and risk factors, and avenues of prevention and treatment. Novel directions for future investigation are also addressed.
Infection Associated with Tunneled Hemodialysis Catheters
Authors: Beathard Gerald A. , Urbanes Aris
Published: October 2008

The use of tunneled dialysis catheters to deliver hemodialysis treatment may be associated with major problems. For this reason their use should be minimized as much as possible. Infection is the most serious of these problems. This complication causes very significant morbidity and mortality and has emerged as the primary barrier to long‐term catheter use. Bacteremia is the most serious type of infection associated with catheter use. It can result in metastatic infection and even lead to death of the patient. Prophylaxis is important to decrease the risk of infection. The use of an antibiotic ointment at the exit site until it has healed and the long‐term use of a dressing to cover the exit site are effective in decreasing the incidence of exit‐site infection. With optimal catheter‐use management, it should be possible to reduce the incidence of catheter‐related bacteremia (CRB) to a level in the range of 1/1000 catheter days. Antibiotic and antimicrobial locking solutions show promise and may, if verified in appropriate clinical studies, prove to be important adjuncts to the management of catheter‐dependent patients. Aspirin has been shown to have anti‐staphylococcal activity and warrants further clinical evaluation. The diagnosis of CRB is based upon positive blood cultures in association with typical clinical features. If a simple routine blood culture is positive, along with a high clinical probability based upon the patient’s signs and symptoms, the sensitivity and specificity of the diagnosis is greater than 75%. CRB is in reality a biofilm infection and must be treated as such. Treatment needs to focus on appropriate systemic antibiotics which should be continued for a minimum of 3 weeks and catheter management to remove the biofilm. Catheter exchange has been shown to be effective and should be performed based upon the clinical presentation of the patient. While treatment with a combination of systemic antibiotics and antibiotic locking solution may be effective for gram‐negative infections, this approach does not appear to be a good choice for Staphylococcus aureus CRB.
Surface‐Treated Catheters—A Review
Authors: Dwyer Amy
Published: October 2008

Almost 30% of prevalent hemodialysis patients use catheters for vascular access although outcomes are superior with the use of either an arteriovenous fistula or a synthetic graft. Catheter complications are a major cause of morbidity and mortality for hemodialysis patients and increase the burden on the health care system. Surface‐treated catheters have been developed to combat the three most common causes of catheter failure: infection, fibrin sheath formation, and thrombus formation. Two types of catheter surface treatments are available: antimicrobial coatings and antithrombotic coatings. Surface treatment of central venous catheters with antimicrobial materials reduces both bacterial colonization and the incidence of catheter‐related bacteremia in critical care patients by 30–50%. Antithrombotic coatings reduce platelet adhesion, inhibit the inflammatory response, and reduce thrombus formation on coronary stents, ventricular assist devices, central venous catheters, and vascular grafts. However, few reports on the use of surface‐treated catheters in the chronic hemodialysis patient population exist. At the present time, it is difficult to justify the increased cost of surface‐treated catheters for chronic hemodialysis in the absence of clinical data demonstrating that they reduce catheter‐related complications in this patient population.
Catheter‐Related Mortality among ESRD Patients
Authors: Wasse Haimanot
Published: October 2008

Hemodialysis access‐related complications remain one of the most important sources of morbidity and cost among persons with end‐stage renal disease, with total annual costs exceeding $1 billion annually. In this context, the creation and maintenance of an effective hemodialysis vascular access is essential for safe and adequate hemodialysis therapy. Multiple reports have documented the type of vascular access used for dialysis and associated risk of infection and mortality. Undoubtedly, the central venous catheter (CVC) is associated with the greatest risk of infection‐related and all‐cause mortality compared with the autogenous arteriovenous fistula (AVF) or synthetic graft (AVG). The AVF has the lowest risk of infection, longer patency rates, greater quality of life, and lower all‐cause mortality compared with the AVG or CVC. It is for these reasons that the National Kidney Foundation’s Kidney Disease Outcome Quality Initiative Clinical Practice Guidelines for Vascular Access recommend the early placement and use of the AVF among at least 50% of incident hemodialysis patients. This report presents catheter‐related mortality and calls for heightened awareness of catheter‐related complications.
High‐Resolution Ultrasound Elasticity Imaging to Evaluate Dialysis Fistula Stenosis
Authors: Weitzel William F. , Kim Kang , Park Dae Woo , Hamilton James , O’Donnell Matthew , Cichonski Thomas J. , Rubin Jonathan M.
Published: October 2008

Accurate, noninvasive characterization of arterial wall mechanics and detection of fibrotic vascular lesions could vastly improve the ability to predict patient response to local treatments such as angioplasty. Current imaging and other techniques for determining wall compliance rely on imprecise or indirect estimates of wall motion. This study used high‐resolution ultrasound imaging with phase‐sensitive speckle tracking to obtain detailed and direct measurements of arterial stiffness in two subjects with dialysis fistula dysfunction. In both subjects, the absolute values of strain were much higher in normal regions of fistula than in regions of stenosis. The lower values of strain in stenotic fistula indicate greater stiffness of the vessel wall. The ultrasound speckle tracking technique used here may have potential to determine vascular mechanical properties noninvasively with a level of precision and accuracy not currently available.
Seasonal Variation of Migraine in an Arctic Population
Authors: Lilleng Hallvard , Bekkelund Svein
Published: October 2008

Objectives.— To investigate seasonal variation of migraine headache in a population residing in an extreme Arctic locale.

Background.— Exposure to light may trigger migraine attacks and patients may also be hypersensitive to light between the attacks. In previous studies of migraine in Northern latitudes we have demonstrated that patients with migraine experience more attacks in the summer. In order to confirm this finding and gain more insight into a possible north‐south effect of seasonal migraine variation, we performed a population‐based study in Svalbard, which is one of the northernmost populated areas of the world.

Method.— A postal questionnaire was mailed to all inhabitants aged 12 years or older living in Svalbard and the migraine diagnosis made by a structured telephone interview.

Results.— Of a total of 1569, 1029 (66%) returned the questionnaire. Of them, 184 (18%) experienced headache within the recent year prior to the study that could not be explained by alcohol, trauma, or viral infections. Eighty‐eight individuals had migraine according to the revised criteria set by the International Headache Society. Nineteen (22%) reported seasonal variation of migraine. Ten (12%) experienced more migraine in the light season, while 9 (10%) got worse in the dark season. No differences in proportions of migraine with aura (MA) and migraine without aura (MO) could be detected. Also, the frequency of MA patients who used sunglasses to avoid migraine headache was nonstatistically increased compared with MO.

Conclusion.— There was no indication of more seasonal variation of headache in a population of otherwise healthy people with migraine living in an extreme Arctic area with long periods of midnight sun and polar nights with complete darkness. The strength of conclusion, however, is significantly limited by a low response rate and small sample size.
Recurrent Wernicke's Aphasia: Migraine and Not Stroke!
Authors: Mishra Nishant Kumar , Rossetti Andrea O. , Ménétrey André , Carota Antonio
Published: October 2008

We report the clinical findings of a 40‐year‐old woman with recurrent migraine presenting with Wernicke's aphasia in accordance with the results of a standardized battery for language assessment (Boston Aphasia Diagnostic Examination). The patient had no evidence of parenchymal or vascular lesions on MRI and showed delta and theta slowing over the left posterior temporal leads on the EEG. Although the acute onset of a fluent aphasia suggested stroke as a likely etiology, the recurrence of aphasia as the initial symptom of migraine was related to cortical spreading depression and not to stroke.
Diagnostic Delay and Suboptimal Management in a Referral Population With Hemicrania Continua
Authors: Rossi Paolo , Faroni Jessica , Tassorelli Christina , Nappi Giuseppe
Published: October 2008

Aim of the Study.— To investigate a clinical population of patients with hemicrania continua (HC), looking at the diagnostic problems they have encountered and their use of healthcare resources and at issues relating to the effectiveness of treatments.

Materials and Methods.— We directly interviewed 25 patients fulfilling the International Classification of Headache Disorders, 2nd edition diagnostic criteria for HC selected among 1612 subjects attending the INI Grottaferrata Headache Clinic over a 3‐year period.

Results.— No patient had received a correct diagnosis before being seen at our headache clinic. In total, 85% of the patients consulted a physician within 5 months of the onset of the symptoms but mean time to diagnosis was 5 years (SD 4.9). The average number of physicians seen before the condition was properly diagnosed was 4.6 (SD 2.2). General practitioners (100%), neurologists (80%), ear, nose, and throat surgeons (44%), ophthalmologists (40%), and dentists (32%) were the physicians most commonly consulted. All the patients had previously received an incorrect diagnosis. Migraine (52%), CH (28%), sinus headache (20%), and dental pain (20%) were the most common wrong diagnoses reported. Some 36.0% of patients had undergone ineffective invasive treatments. The patients had tried, on average, 3.6 (SD 2.1) classes of drugs. Nonsteroidal anti‐inflammatory drugs (NSAIDs) (92%), triptans (32%), antidepressants (32%), and antiepileptics (24%) were the most commonly used. Patients rated 73.7% of medications as ineffective, 22.5% (all NSAIDs) as partially effective, and 3.7% (rofecoxib and nimesulide) as effective.

Conclusions.— Hemicrania continua may be misdiagnosed and mistreated even by neurologists. There is a need for greater awareness and understanding of this condition.
The Use of a Standard Radiofrequency Energy Delivery System to Facilitate Transseptal Puncture
Authors: McWILLIAMS MICHAEL J. , TCHOU PATRICK
Published: October 2008

Transseptal puncture is a standard means of catheter access to the left atrium via the venous system, but carries a risk of cardiac perforation. Stretching and increased force to traverse the septum are required with elastic, aneurysmal, or thickened interatrial tissue. We describe a technique that facilitates transseptal puncture by applying brief pulses of radiofrequency energy from a standard electrosurgical cautery generator through the needle tip.
Single‐Catheter Technique for Pulmonary Vein Antrum Isolation: Is It Sufficient to Identify and Close the Residual Gaps Without a Circular Mapping Catheter?
Authors: DONG JIANZENG , LIU XINGPENG , LONG DEYONG , YU RONGHUI , TANG RIBO , LÜ FEI , MA CHANGSHENG
Published: October 2008

Single Catheter for Pulmonary Vein Isolation.
Objectives: The present study was designed to investigate the feasibility and efficacy of single ablation catheter for complete circumferential pulmonary vein antrum (PVA) isolation.

Background: Complete isolation of pulmonary veins is the mainstay for atrial fibrillation (AF) ablation. This is usually performed under the guidance of a circular catheter.

Methods: One hundred and ten consecutive patients with paroxysmal AF were prospectively randomized into two groups: single‐catheter approach (group 1) and double‐catheter approach (group 2). After performing initial circumferential lesions, residual gaps were mapped and closed with single ablation catheter in group 1 or guided by a circular mapping catheter in group 2 using an electroanatomic mapping system (CARTO™ XP, Biosense‐Webster Inc., Diamond Bar, CA, USA).

Results: Complete bilateral PVA isolation was achieved in 22 of the 110 patients after initial ablation. All residual gaps could be correctly identified by activation mapping using single ablation catheter. The distribution of these residual gaps was asymmetric. In group 1, 25 gaps along the right PVA lesions and 49 gaps along the left PVA lesions were identified. All the residual gaps were closed with single‐catheter approach. In group 2, 28 gaps on the right side and 53 gaps on the left side were identified using a circular catheter and closed with further ablations. The procedure data and clinical outcomes between the two groups were comparable.

Conclusions: Single ablation catheter technique is feasible and as effective as circular catheter mapping in localizing the residual gaps for PVA isolation during ablation of paroxysmal AF. (J Cardiovasc Electrophysiol, Vol. 20, pp. 273‐279, March 2009)
Ventricular Fibrillation with Prominent Early Repolarization Associated with a Rare Variant of KCNJ8/KATP Channel
Authors: HAÏSSAGUERRE MICHEL , CHATEL STÉPHANIE , SACHER FREDERIC , WEERASOORIYA RUKSHEN , PROBST VINCENT , LOUSSOUARN GILDAS , HORLITZ MARC , LIERSCH RUEDIGE , SCHULZE‐BAHR ERIC , WILDE ARTHUR , KÄÄB STEFAN , KOSTER JOSEPH , RUDY YORAM , MAREC HERVÉ LE , SCHOTT JEAN JACQUES
Published: October 2008

Background:
Early repolarization in the inferolateral leads has been recently recognized as a frequent syndrome associated with idiopathic ventricular fibrillation (VF). We report the case of a patient presenting dramatic changes in the ECG in association with recurrent VF in whom a novel genetic variant has been identified.

Case Report:
This young female (14 years) was resuscitated in 2001 following an episode of sudden death due to VF. All examinations including coronary angiogram with ergonovine injection, MRI, and flecainide or isoproterenol infusion were normal. The patient had multiple (>100) recurrences of VF unresponsive to beta‐blockers, lidocaine/mexiletine, verapamil, and amiodarone. Recurrences of VF were associated with massive accentuation of the early repolarization pattern at times mimicking acute myocardial ischemia. Coronary angiography during an episode with 1.2 mV J/ST elevation was normal. Isoproterenol infusion acutely suppressed electrical storms, while quinidine eliminated all recurrences of VF and restored a normal ECG over a follow‐up of 65 months. Genomic DNA sequencing of KATP channel genes showed missense variant in exon 3 (NC_000012) of the KCNJ8 gene, a subunit of the KATP channel, conferring predisposition to dramatic repolarization changes and ventricular vulnerability.
Malignant Ventricular Arrhythmia in a Case of Adult Onset of Spinal Muscular Atrophy (Kugelberg–Welander Disease)
Authors: ROOS MARKUS , SARKOZY ANDREA , CHIERCHIA GIAN BATTISTA , DE WILDE PHILIPPE , SCHMEDDING ERIC , BRUGADA PEDRO
Published: October 2008

Adult‐Onset KWD and Arrhythmia. We present a case of a 43‐year‐old male patient with adult onset of spinal muscular atrophy (SMA). The patient first came to our attention with atrioventricular (AV) block. A dual‐chamber pacemaker (DDD‐PM) was implanted. Four years later, the PM data log showed occurrence of frequent episodes of nonsustained ventricular tachycardia (NSVT). The episodes progressed in duration and frequency. An electrophysiological study revealed prolonged His‐ventricular (HV) interval duration and induction of sustained ventricular tachycardia. The patient was successfully upgraded to a prophylactic dual‐chamber cardioverter defibrillator. Our case is the first description of a patient with adult‐onset SMA (Kugelberg–Welander disease [KWD]) and malignant ventricular arrhythmias. (J Cardiovasc Electrophysiol, Vol. 20, pp. 342‐344, March 2009)
Feeding and Grazing Impact by Small Marine Heterotrophic Dinoflagellates on Heterotrophic Bacteria
Authors: JEONG HAE JIN , SEONG KYEONG AH , YOO YEONG DU , KIM TAE HOON , KANG NAM SEON , KIM SHIN , PARK JAE YEON , KIM JAE SEONG , KIM GWANG HOON , SONG JAE YOON
Published: October 2008

ABSTRACT. We investigated the feeding of the small heterotrophic dinoflagellates (HTDs) Oxyrrhis marina, Gyrodinium cf. guttula, Gyrodinium sp., Pfiesteria piscicida, and Protoperidinium bipes on marine heterotrophic bacteria. To investigate whether they are able to feed on bacteria, we observed the protoplasm of target heterotrophic dinoflagellate cells under an epifluorescence microscope and transmission electron microscope. In addition, we measured ingestion rates of the dominant heterotrophic dinoflagellate, Gyrodinium spp., on natural populations of marine bacteria (mostly heterotrophic bacteria) in Masan Bay, Korea in 2006–2007. Furthermore, we measured the ingestion rates of O. marina, G. cf. guttula, and P. piscicida on bacteria as a function of bacterial concentration under laboratory conditions. All HTDs tested were able to feed on a single bacterium. Oxyrrhis marina and Gyrodinium spp. intercepted and then ingested a single bacterial cell in feeding currents that were generated by the flagella of the predators. During the field experiments, the ingestion rates and grazing coefficients of Gyrodinium spp. on natural populations of bacteria were 14–61 bacteria/dinoflagellate/h and 0.003–0.972 day−1, respectively. With increasing prey concentration, the ingestion rates of O. marina, G. cf. guttula, and P. piscicida on bacteria increased rapidly at prey concentrations of ca 0.7–2.2 × 106 cells/ml, but increased only slowly or became saturated at higher prey concentrations. The maximum ingestion rate of O. marina on bacteria was much higher than those of G. cf. guttula and P. piscicida. Bacteria alone supported the growth of O. marina. The results of the present study suggest that some HTDs may sometimes have a considerable grazing impact on populations of marine bacteria, and that bacteria may be important prey.
A Proteomics Approach to Cloning Fenestrin from the Nuclear Exchange Junction of Tetrahymena
Authors: COLE ERIC S. , ANDERSON PAUL C. , FULTON ROSS B. , MAJERUS MATTHEW E. , ROONEY MEGAN G. , SAVAGE JOHANNA M. , CHALKER DOUGLAS , HONTS JERRY , WELCH MARY E. , WENTLAND AMY L. , ZWEIFEL ERICA , BEUSSMAN DOUGLAS J.
Published: October 2008

ABSTRACT. We set out to find the “fenestrin” gene, a gene whose protein is associated with numerous cellular apertures, including the nuclear exchange junction in mating Tetrahymena thermophila. First we developed protocols for imaging and isolating intact nuclear exchange junctions from conjugating cells. Proteins from these junctions were purified using SDS‐PAGE, subjected to limited proteolysis, and precise molecular weights were determined by mass spectrometry. Using Protein Prospector® software and the published Tetrahymena Genome Database, genes for 15 of the most abundant proteins found in our extracts were identified. The most promising candidate was cloned by PCR, fused to yellow fluorescent protein (YFP), and placed under the control of an inducible metallothionein promoter. YFP‐localization within live Tetrahymena transformants strongly suggested that one of these genes encoded the fenestrin protein, a result that was subsequently confirmed by Western blotting.
Distribution and Host Range of the Microsporidian Pleistophora mulleri
Authors: IRONSIDE JOSEPH E. , WILKINSON TOBY J. , ROCK JENNIFER
Published: October 2008

ABSTRACT. Microsporidia of the genus Pleistophora are important parasites of fish and crustacea. Pleistophora mulleri has been described previously as a parasite of the gammarid amphipod crustacean Gammarus duebeni celticus in Irish freshwater habitats. Through a survey of European G. duebeni populations, P. mulleri was found to be widely distributed in the western British Isles (Wales, Scotland, and the Isle of Man), and populations of the subspecies Gammarus duebeni duebeni as well as G. d. celticus were infected. Pleistophora infections were also detected in G. d. duebeni sampled from the Bay of Gdansk on Poland's Baltic coast, indicating a wide distribution of Pleistophora in European G. duebeni. Sequencing and phylogenetic analysis of the 16S rRNA, 18S rRNA, and Rpb1 genes of P. mulleri suggest that this species may be synonymous with P. typicalis, a parasite of fish. These findings suggest that amphipod crustaceans may act as intermediate or reservoir hosts for microsporidian parasites of fish.
Colloidal Stability for Concentrated Zirconia Aqueous Suspensions
Authors: Rami Marie‐Laure , Meireles Martine , Cabane Bernard , Guizard Christian
Published: October 2008

This work started as part of an investigation into the mechanisms by which fine zirconia aqueous dispersions can be processed for ceramic materials engineering. Aqueous dispersions of TZ3Y fine zirconia particles obtained by dispersion of dry powder in acidic solutions (pH 3) have been subjected to compression through osmotic experiments. The results show a behavior that is unusual when compared with the classical behavior of colloidal dispersions. Indeed, the 50 nm particles are well dispersed and protected from aggregation by electrical double layers, with a high zeta potential (60–80 mV). Yet, during osmotic compression, the dispersion goes from a liquid state to a gel state at a rather low volume fraction, φ=0.2, whereas the liquid–solid transition for repelling particles is expected to occur only at φ=0.5. This early transition to a state in which the dispersion does not flow may be a severe drawback in some uses of these dispersions, and thus it is important to understand its causes. A possible cause of this early aggregation is the presence of a population of very small particles, which are seen in osmotic stress experiments and in light scattering. We propose that aggregation could result from the compression of this population, through either of the following mechanisms: (a) An increase in pressure causes the small particles to aggregate with each other and with the larger ones or (b) An increase in pressure induces a depletion flocculation phenomenon, in which the large particles are pushed together by the smaller ones.
Cofiring of Thin Zirconia Films During SOFC Manufacturing
Authors: Mücke Robert , Menzler Norbert H. , Buchkremer Hans Peter , Stöver Detlev
Published: October 2008

High‐performance solid oxide fuel cells require a thin and gas‐tight electrolyte membrane that must be coated on a porous and relatively rough support. A pretreatment of the delivered submicronmeter electrolyte powder of 8 mol%‐yttria‐stabilized zirconia (8YSZ) yielded a reduced sintering mismatch between the anode substrate made from NiO/8YSZ and the electrolyte coating. Furthermore, it also enhanced the powder packing inside the green film. Constrained sintering usually leads to inadequate film density and an unfavorable pore deformation and orientation. It was demonstrated that these limitations can be resolved by using a coshrinking substrate in a planar cell design. Relative densities of >97% were achieved, which are higher than those for free‐standing layers. Additionally, the camber behavior was investigated in dependence of the temperature program with and without gravity effects, giving an overall suggestion for the cofiring parameters of the electrolyte.
Improved Oxidation Resistance of Zirconium Diboride by Tungsten Carbide Additions
Authors: Zhang Shi C. , Hilmas Greg E. , Fahrenholtz William G.
Published: October 2008

The effect of tungsten carbide (WC) additions on the oxidation resistance of zirconium diboride (ZrB2) was studied. Zirconium diboride ceramics, nominally pure and with the addition of 4 mol% WC, were densified by pressureless sintering. During densification, the WC that was added to the ceramic dissolved into the ZrB2 matrix, forming a solid solution. Oxidation behavior was evaluated using thermal gravimetric analysis up to 1500°C and isothermal furnace oxidation at 1500° and 1600°C. The WC additions reduced both the weight gain and the oxide scale thickness. After oxidation at 1600°C for 3 h, the mass gain decreased from 22 mg/cm2 for nominally pure ZrB2 to 8 mg/cm2 for the WC‐containing ceramic. Analysis showed that the WC additions improved the oxidation resistance of ZrB2 by promoting densification of the zirconia scale formed during oxidation through liquid‐phase sintering.
Mesostructured Silica for Optical Functionality, Nanomachines, and Drug Delivery
Authors: Klichko Yaroslav , Liong Monty , Choi Eunshil , Angelos Sarah , Nel Andre E. , Stoddart J. Fraser , Tamanoi Fuyuhiko , Zink Jeffrey I.
Published: October 2008

Silica thin films and nanoparticles prepared using sol–gel chemistry are derivatized with active molecules to generate new functional materials. The mild conditions associated with sol–gel processing allow for the incorporation of a range of dopants including organic or inorganic dyes, biomolecules, surfactants, and molecular machines. Silica nanoparticles embedded with inorganic nanocrystals, and films containing living cells have also been synthesized. Silica templated with surfactants to create mesostructure contains physically and chemically different regions that can be selectively derivatized using defined techniques to create dynamic materials. Using two different techniques, donor–acceptor pairs can be doped into separated regions simultaneously and photo‐induced electron transfer between the molecules can be measured. Mesoporous silica materials are also useful supports for molecular machines. Machines including snap‐tops and nanoimpellers that are designed to control the release of guest molecules trapped within the pores are described. Mesoporous silica nanoparticles are promising materials for drug delivery and other biomedical applications because they are nontoxic and can be taken up by living cells. Through appropriate design and synthesis, multifunctional mesoporous silica nanoparticles for sophisticated bio‐applications are created.
Inhibition of phagocytic activity and nodulation in Galleria mellonella by the entomopathogenic fungus Nomuraea rileyi
Authors: Tseng Y. K. , Tsai Y. W. , Wu M. S. , Hou Roger F.
Published: October 2008

Changes in phagocytic activity and nodulation in the greater wax moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae), were examined after treatment with the culture fluid of the entomopathogenic fungus Nomuraea rileyi SH1. When isolated hemocytes of G. mellonella were incubated with the conidia of N. rileyi in vitro, the rates of phagocytosis increased at 4 h after incubation but decreased subsequently. On the contrary, the rates of phagocytosis of isolated hemocytes decreased by 80% after 24 h preincubation with the fungal culture fluid (1/200, 1/100 dilutions). Levels of inhibition of phagocytic activity by the culture fluid depended on dilutions used. Galleria mellonella larvae showed a peak of nodulation at 4 h after injection with conidia. The percentage of nodules in hemolymph did not decrease by preinjection with the culture fluid, whereas the percentage of nodule‐containing conidia decreased, depending on the injected fluid. However, phagocytosis and nodulation in G. mellonella did not change after treatment of the culture fluid with proteinase K, indicating that the culture fluid contained proteinaceous immunosuppressive factors. Electrophoretic analysis of the culture fluid and not the fresh medium without culturing the fungus exhibited protein bands. Therefore, N. rileyi possibly secretes toxic proteins that impair cellular immune responses in G. mellonella larvae.
How do food quality and larval crowding affect performance of the autumnal moth, Epirrita autumnata?
Authors: Sillanpää Saila
Published: October 2008

Outbreak densities of autumnal moth, Epirrita autumnata (Borkhausen) (Lepidoptera: Geometridae), lead to high larval crowding. Phenotypic responses of E. autumnata to larval crowding and to food quality were studied by measuring growth and consumption as well as pupal weight and fecundity. Crowding may trigger increased consumption and faster development to avoid impending food shortage on good quality food. This is suggested by the result that on a good‐quality diet, the growth of crowded larvae was better than that of solitary larvae, though they did not consume more food than solitary larvae. Crowded larvae also completed the last instar earlier than solitary larvae. The fecundity of crowded autumnal moths was not lower than the fecundity of solitarily grown autumnal moths. This may provide conditions for extra rapid population build‐up of E. autumnata. During the population increase phase the crowding effect may facilitate larval performance; however, at peak density the crowding starts to have negative effects on the performance of larvae. On a poor‐quality diet, the performance of crowded and solitary larvae did not differ. The growth of larvae was better on a good‐quality diet than on a poor‐quality diet, due to higher efficiency in food utilization. Larvae feeding on low‐quality diet did not prolong their development time, but pupated at smaller size; this resulted in lower fecundity. A decrease in food quality can be seen as a cue of oncoming food shortage and resource depletion; it may be advantageous to pupate at a smaller size and ensure survival till reproduction, rather than risk prolonging development to achieve larger size and higher fecundity.
An ensemble model for predicting Rhopalosiphum padi abundance
Authors: Lankin‐Vega G. , Worner S. P. , Teulon D. A. J.
Published: October 2008

A novel modeling method is proposed to predict the abundance of the main vector of barley yellow dwarf virus in autumn sown cereal crops. An ensemble model based on artificial neural networks (ANN) was developed to predict the number of Rhopalosiphum padi (L.) (Homoptera: Aphididae) caught in traps during the autumn flight period at Lincoln, Canterbury, New Zealand, over the period 1982–2003. Artificial neural networks were trained using historical weather data and aphid data collected from a suction trap. Model results were compared with those obtained using multiple regression (MR) models using the same independent variables. Both ANN and MR models were validated by leave‐one‐out validation, in other words, by sequentially jackknifing each year out of the data set, fitting a model to the remaining data, then using that model to predict the number of aphids for each jackknifed year. A linear ensemble of ANN models further improved the predictions and represented the trends in the number of aphids over the 22‐year period very well. The r2 between the predicted and observed numbers of aphids for the ANN models changed from 0.68 to 0.83 using the linear ensemble model, but the ensemble approach did not change the prediction for the MR models. The absolute mean error (ABSME) of prediction was much lower for the ANN ensemble predictions compared to that for the MR models. The ABMSE for the ANN models dropped from 109 to 86 aphids compared to an ABMSE reduction from 245 to 220 aphids for the MR models. We discuss the potential for ensemble models for predicting insect abundance when long‐term historical data are available.
Quantifying the effects of host discrimination on egg‐laying decision of the cowpea seed beetle, Callosobruchus maculatus
Authors: Yang R.‐L. , Fushing H.
Published: October 2008

Many parasitic and endophagous insect species are capable of discriminating among the quality of their hosts. However, there is no appropriate way to quantify their discrimination performance. In this study, we quantified how oviposition of the cowpea seed beetle, Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae), was affected by the relative contributions of both egg number and host size discrimination. The effect of egg density and resource heterogeneity on these discrimination performances was also explored. Egg‐distribution predictions were made by combining time‐dependent available resource fitness (egg discrimination) and host weight factors (size discrimination). The χ2 test was then used for goodness‐of‐fit testing. The effects of both egg and size discrimination on oviposition in environments with different levels of resource heterogeneity were compared. It was found that host size, rather than the number of eggs on the host, plays a larger role in the egg‐laying decision for most individual seed beetles, especially when egg density is high. Host size discrimination behavior was reinforced when the beetles experienced increasing resource heterogeneity, but the performance might reach a plateau. This is the first quantitative evaluation of the effect of host discrimination on egg‐laying decisions of seed beetles.
The effect of soil depth and exposure to winter conditions on survival of the potato tuberworm, Phthorimaea operculella
Authors: Doǧramacı Mahmut , Rondon Silvia I. , DeBano Sandra J.
Published: October 2008

The potato tuberworm, Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), is an important pest of solanaceous crops including potato [Solanum tuberosum L. (Solanaceae)]. Recent evidence of survival of the pest in the Columbia Basin of Oregon and Washington, USA, is surprising as potato tuberworm is most commonly a pest in tropical and subtropical regions. Potato tuberworm was studied in a manipulative experiment to determine how stage (egg, larva, and pupa) and soil depth affected the potential for winter survival. In early January 2007, eggs, tubers infested with larvae, and pupae were placed in the soil at 6, 10, and 20 cm depths, or left on the soil surface. Each potato tuberworm life stage was sampled at 7–17‐day intervals for 90 days and survival was estimated at each time period. Eggs survived up to 54 days with the greatest survival observed at 6‐cm soil depth and the lowest survival on the soil surface. However, egg survival was significantly reduced after 1 month of exposure to winter conditions. Larvae were able to survive up to 30 days with the greatest survival observed at 20‐cm soil depth. Tubers at the surface and buried at 6 cm were frozen; thus, no larval survival was recorded. The pupal stage showed a greater tolerance to winter conditions than the egg or larval stages, surviving up to 91 days of exposure. These results suggest that the pupal stage is probably the stage most likely to survive winter conditions in the northwestern USA.
Alternative life histories in the water strider Gerris lacustris: time constraint on wing morph and voltinism
Authors: Pfenning Brenda , Gerstner Sabine , Poethke Hans Joachim
Published: October 2008

The wing dimorphic water strider Gerris lacustris L. (Heteroptera: Gerridae) switches to a bivoltine life cycle under favorable climatic conditions. The switch in voltinism is accompanied by a reduction of wing development in the directly reproducing midsummer generation, while the diapausing generation has a high fraction of long‐winged individuals. We investigated whether the thermal energy (degree‐days) available in natural habitats constrains the combination of developmental pathway and wing morph. Offspring of G. lacustris were reared under quasi‐natural conditions at two temperature regimes to determine the thermal constant k required to complete adult development in either wing morph. The thermal constant for egg‐to‐adult development of the short‐winged morph was about 20% lower than of the long‐winged morph. Based on the results from the outdoor laboratory experiment, we calculated the total degree‐days necessary to complete the possible combinations of wing morph pattern and voltinism. Comparison of these estimates with the thermal energy actually available during the reproductive season of 2004 for various natural habitats (sun‐exposed field ponds and shaded forest ponds) suggests that voltinism as well as wing morph pattern is strongly limited by the number of degree‐days available in these habitats. On forest ponds, only univoltine life cycles were possible, whereas on field ponds temperature allowed bivoltine life cycles. However, only the eggs laid at the very beginning of the season had the potential to accumulate enough degree‐days to complete a bivoltine life cycle with both generations long‐winged. We conclude that thermal energy is the main environmental constraint limiting voltinism of populations in the two habitat types. Furthermore, the available thermal energy also seems to influence the determination of the seasonal wing pattern in G. lacustris.
Semi‐field evaluation of a granulovirus and Bacillus thuringiensis ssp. kurstaki for season‐long control of the potato tuber moth, Phthorimaea operculella
Authors: Arthurs Steven P. , Lacey Lawrence A. , Pruneda Jonathan N. , Rondon Silvia I.
Published: October 2008

There are few insecticidal options for potato tuber moth (PTM), Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), control late in the growing season. We evaluated the PTM granulovirus (PoGV) and Bacillus thuringiensis Berliner ssp. kurstaki (Btk) for season‐long control of PTM on potato foliage in 2006 and 2007. Compared to untreated controls, 10 weekly applications of PoGV (1013 occlusion bodies/ha) reduced PTM populations in replicated 1‐m3 field cages by 86–96% on pre‐harvest foliage and 90–97% on tubers added to cages shortly before harvest. Infection rates of 82–95% of L4 larvae by PoGV were noted within individual larval cohorts. Equivalently timed Btk treatments (1.12 kg product/ha) were significantly less effective at population suppression, with a 36–76% reduction in larvae recovered from tubers added to cages. A PoGV/Btk alternation was significantly more effective than Btk alone and as effective as PoGV in 2007, but not in 2006. There was some evidence that reduced rate PoGV treatments (10% rate or 50% application frequency) were less effective than the standard program. There were no treatment effects on percentage of tubers growing in the ground that were infested at harvest, which remained comparatively low at ≤8.1%. Bioassays were conducted to evaluate the residual activities of foliar deposits. Early‐season applications were highly effective for the first 24 h (≥93% mortality) with a steady decline in activity over 10 days. A second application, applied later in the season, showed similar patterns, although in this case Btk was less persistent than PoGV, whereas both agents provided significant larval mortality compared with controls over 14 days. Both PoGV and Btk provide alternatives to manage field infestations of PTM prior to harvest, thus reducing the risk of tuber infestations in storage.
The molecular machines that mediate microRNA maturation
Authors: Lau Pick‐Wei , MacRae Ian J.
Published: October 2008

Introduction

miRNAs originate from primary RNA transcripts

The Microprocessor initiates miRNA processing

Nuclear proteins regulate activity of the Microprocessor

Intronic pre‐miRNAs can bypass the Microprocessor

The Exportin‐5 Complex transports pre‐miRNA to the cytoplasm

The RISC‐Loading Complex completes miRNA maturation

Mature miRNAs silence target genes from within RISC

Discussion and future directions

MicroRNAs (miRNA) are small RNAs that regulate the translation of thousands of message RNAs and play a profound role in mammalian biology. Over the past 5 years, significant advances have been made towards understanding the pathways that generate miRNAs and the mechanisms by which miRNAs exert their regulatory functions. An emerging theme is that miRNAs are both generated by and utilized by large and complex macromolecular assemblies. Here, we review the biology of mammalian miRNAs with a focus on the macromolecular complexes that generate and control the biogenesis of miRNAs.
Stem cells are resistant to TRAIL receptor‐mediated apoptosis
Authors: Szegezdi Eva , O’Reilly Aoife , Davy Yeung , Vawda Reaz , Taylor Deanna L. , Murphy Mary , Samali Afshin , Mehmet Huseyin
Published: October 2008

New therapeutic approaches aim to eradicate tumours by expression of tumouricidal proteins in the tumour stroma. One such anti‐neoplastic protein is tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL) because it induces apoptosis in cancerous cells, but not in non‐transformed cells. Stem cells can migrate to, survive and proliferate in tumours. We examined the suitability of bone marrow‐derived adult mesenchymal stem cells (bmMSC), foetal‐MSC and umbilical cord matrix stem cells (Wharton’s Jelly MSCs) as TRAIL‐delivery vehicles. Although all MSC types expressed DR4 and/or DR5, none of them were sensitive to TRAIL‐induced apoptosis. Selective activation of DR4 or DR5 with agonistic antibodies or DR5‐selective TRAIL‐mutant (D269H/E195R) revealed that the TRAIL receptors are inactive in MSCs. In fMSC DR5 was not fully inactivated, its activity however was minimal in comparison to the colon carcinoma cell, Colo205. The intracellular components of the TRAIL‐apoptotic pathway, such as pro‐caspase‐8 and ‐9 were also expressed at very low; almost undetectable levels in all three MSC types. In conclusion, the MSC species examined are resistant to TRAIL and thus can be suitable tools for TRAIL delivery to tumours.
miRNAS in normal and diseased skeletal muscle
Authors: Eisenberg Iris , Alexander Matthew S. , Kunkel Louis M.
Published: October 2008

Introduction

Mechanisms of miRNA‐mediated repression

miRNA regulatory network in muscle

miRNA signatures as biomarkers of myopathies

miRNA therapeutic promise

Perspective

The last 20 years have witnessed major advances in the understanding of muscle diseases and significant inroads are being made to treat muscular dystrophy. However, no curative therapy is currently available for any of the muscular dystrophies, despite the immense progress made using several approaches and only palliative and symptomatic treatment is available for patients. The discovery of miRNAs as new and important regulators of gene expression is expected to broaden our biological understanding of the regulatory mechanism in muscle by adding another dimension of regulation to the diversity and complexity of gene‐regulatory networks. As important regulators of muscle development, unravelling the regulatory circuits involved may be challenging, given that a single miRNA can regulate the expression of many mRNA targets. Although the identification of the regulatory targets of miRNAs in muscle is a challenge, it will be critical for placing them in genetic pathways and biological contexts. Therefore, combining informatics, biochemical and genetic approaches will not only expected to reveal the elucidation of the miRNA regulatory network in skeletal muscle and to bring a better knowledge on muscle tissue regulation but will also raise new opportunities for therapeutic intervention in muscular dystrophies by identifying candidate miRNAs as potential targets for clinical application.
Activation of epidermal growth factor receptor results in Snail protein but not mRNA overexpression in endometrial cancer
Authors: Hipp Susanne , Walch Axel , Schuster Tibor , Losko Sascha , Laux Holger , Bolton T. , Höfler Heinz , Becker Karl‐Friedrich
Published: October 2008

Reduced E‐cadherin expression is associated with tumour progression of many carcinomas, including endometrial cancers. The transcription factor Snail is known as one of the most prominent transcriptional E‐cadherin repressors; its regulation in cancer tissues, however, still remains unclear. Here, we report that activation of epidermal growth factor receptor (EGFR) resulted in overexpression of Snail and also identified critical downstream signalling molecules. Stimulation of two endometrial carcinoma cell lines with epidermal growth factor (EGF) lead to an increase of Snail protein expression. In primary human endometrioid endometrial carcinomas Snail protein expression correlated with the activated, phosphorylated form of EGFR (Tyr1086) as revealed by profiling 24 different signalling proteins using protein lysate microarrays. In addition, we observed an inverse correlation between Snail and E‐cadherin protein levels in these tumours. Most likely, p38 MAPK, PAK1, AKT, ERK1/2 and GSK‐3β are involved in the up‐regulation of Snail downstream of EGFR. Snail mRNA expression did not show a correlation with activated EGFR in these tumours. Taken together, profiling of signalling proteins in primary human tissues provided strong evidence that EGFR signalling is involved in Snail protein overexpression.