bluuebunny/crossref_metadata_2025 huggingface dataset:
Post Fuel Injection Fuel Vaporization Characteristics in the Intake Port of a Port-Fuel-Injected Gasoline CFR Engine
Authors: Cowart Jim S. , Hamilton Leonard J.
Published: September 2008

A Cooperative Fuels Research (CFR) gasoline engine has been modified to run on computer controlled Port Fuel Injection (PFI) and electronic ignition. Additionally a fast acting sampling valve (controlled by the engine control computer) has been placed in the engine’s intake system between the fuel injector and cylinder head in order to measure the fuel components that are vaporizing in the intake port immediately after the fuel injection event, and separately during the intake valve open period. This is accomplished by fast sampling a small portion of the intake port gases during a specified portion of the engine cycle which are then analyzed with a gas chromatograph. Experimental mixture preparation results as a function of inlet port temperature and pressure are presented. As the inlet port operates at higher temperatures and lower manifold pressures more of the injected fuels’ heavier components evolve into the vapor form immediately after fuel injection. The post-fuel injection fuel-air equivalence ratio in the intake port is characterized. The role of the fuel injection event is to produce from 1/4 to slightly over 1/2 of the combustible fuel-air mixture needed by the engine, as a function of port temperature. Fuel vapor sampling during the intake valve open period suggests that very little fuel is vaporizing from the intake port puddle below the fuel injector. In-cylinder fuel vapor sampling shows that significant fuel vapor generation must occur in the lower intake port and intake valve region.
DPF Soot Profile Features Accounting for Engine Duty Cycle
Authors: Chiavola O. , Falcucci G. , Chiatti G.
Published: September 2008

An investigation of Diesel Particulate Filter (DPF) is performed to obtain deeper insight into the soot loading process. Previous paper has been devoted to the realization of a numerical model to analyse how diesel soot is deposited on the walls of a commercial filter media and to understand the influence of different engine operating conditions on the soot layer growth. The results have been validated by means of experimental data. This paper concerns with the parametrization of particulate deposition profiles and focuses on how soot profile evolves during engine operation in a specified duty cycle, starting from pre-loaded channels. Results of 3D CFD simulations are presented, in which different engine running histories are analyzed.
Engine Knock Prediction Using Multi Zone Model for Spark Ignition Engines
Authors: Ahmedi A. , Stenla˚a˚s O. , Sunde´n B. , Egnell R. , Mauss F.
Published: September 2008

Autoignition in SI engines is an abnormal combustion mode and may lead to engine knock in SI engines. Knock may cause damage and it is a source of noise in engines. It limits the compression ratio of the engine and a low compression ratio means low fuel conversion efficiency of the engine. In this paper a multi zone model based on an existing two zone model Hajireza et al., [1 and 12] and Stenla˚a˚s et al., [30] is developed and validated against the experimental results. The validation is done by using the same detailed chemical mechanism consisting of 141 species and about 1405 reactions under the same conditions. The model is a zero dimensional model capable of simulating a full engine cycle. The two zone combustion model consists of a burned and an unburned zone, separated by a thin adiabatic flame front. The multi zone model differs in the handling of the burned gas. In the multi zone case a number of burned zones are present. The number of zones is decided by the temperature difference between the flame front and the last generated burned zone. The detailed chemical mechanism is taken into account in each zone, while the propagating flame front is calculated from the Wiebe function. Each zone is assumed to be a homogeneous mixture with a uniform temperature, mole and mass fractions of species. The spatial variation of the pressure is neglected, i.e., it is assumed to be the same in the whole combustion chamber at every instant of time. Autoignition is handled by the chemical kinetic model. As the unburned zone is assumed homogeneous the effect of auto ignition is a single pressure peak. The model is not designed to predict the pressure oscillations seen in engine knock.
The Combustion Characteristics of n-Heptane Fueled HCCI Engine Operation With Gaseous Fuels Admission
Authors: Liu C. , Karim G. A. , Sohrabi A. , Xiao F.
Published: September 2008

The effects of the introduction of the gaseous fuels, methane, hydrogen and carbon monoxide into the intake of a variable compression ratio n-heptane fuelled HCCI, CFR engine were investigated. The variations in some of the key combustion and operational parameters were determined experimentally. These included cylinder pressure and its rise rate temporal developments, autoignition timing, combustion durations for both the low and high temperature reaction regions, COV values for IMEP and maximum cylinder pressure, and the incidence of knock and its intensity. In parallel with the experimental investigation, results of a numerical simulation of the processes involved obtained by employing a KIVA based approach while incorporating sufficiently detailed chemical kinetics are presented. It was found that supplementing n-heptane HCCI with gaseous fuels could inhibit the low temperature combustion region and delay to varying extents the high temperature combustion region. Methane admission produced lengthening of the delay to autoignition and extended the combustion durations. It is suggested that supplementing the liquid fuel with methane may be a means for controlling the combustion process of a liquid fuelled HCCI engine while obtaining higher power and acceptable levels of emissions without producing unacceptably heavy knock. However, the addition of hydrogen or carbon monoxide could not reduce the intensity of knock while improving power output.
Piston Finite Element Modeling for the Estimation of Hydrodynamic and Contact Forces and Moments
Authors: Panayi Andreas P. , Schock Harold J.
Published: September 2008

Modeling the thermal and mechanical behavior of a piston is crucial, as it allows for the evaluation of piston performance including piston dynamics and friction. These characteristics directly affect the efficiency, reliability, and lifespan of an internal combustion engine. This work migrates from the conventional parameterized piston modeling approach and uses a full CAD finite element modeling simulation for the evaluation of the piston’s thermal and mechanical behavior as well as the resultant hydrodynamic and contact forces and moments experienced by it. The analysis is performed for two different piston to cylinder bore nominal clearances, and for one of them at two different engine speeds, while assuming the piston is moving at the center of the cylinder bore with no transverse or tilting motion.
Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties
Authors: Holmes Jason David
Published: September 2008

Several noise criteria methods commonly used in architectural acoustics have been quantitatively related to noise perception and task performance under a variety of ventilation systems-induced background noise conditions. Noise criteria, balanced noise criteria, room criteria, room criteria mark II, and A-weighted equivalent sound pressure level were examined. The first phase of the project included noise conditions controlled to be non-time-varying and nontonal, with neutral, rumbly, roaring, or hissy characteristics. An intermediate study examined exposure time length and types of performance tasks used. The final phase included noise conditions containing various levels of discrete tones from 120 to 595 Hz. Under each noise, subjects completed performance tasks and perception questionnaires. Results indicate task performance was significantly affected by perception of noise, but this relationship was not fully demonstrated by the criteria systems analyzed. The five criteria were generally well suited in describing subjective loudness perception, but some discrepancies in criteria spectral quality ratings and subjective perception existed. Finally, perception of annoyance changed based on the frequency and prominence of tones in noise, but these changes were not reflected in the criteria level or spectral quality ratings. Modifications to the existing criteria are recommended.
A Neoplastic Gene Fusion Mimics Trans-Splicing of RNAs in Normal Human Cells
Authors: Li Hui , Wang Jinglan , Mor Gil , Sklar Jeffrey
Published: September 2008

Chromosomal rearrangements that create gene fusions are common features of human tumors. The prevailing view is that the resultant chimeric transcripts and proteins are abnormal, tumor-specific products that provide tumor cells with a growth and/or survival advantage. We show that normal endometrial stromal cells contain a specific chimeric RNA joining 5′ exons of the
JAZF1
gene on chromosome 7p15 to 3′ exons of the Polycomb group gene
JJAZ1/SUZ12
on chromosome 17q11 and that this RNA is translated into JAZF1-JJAZ1, a protein with anti-apoptotic activity. The
JAZF1-JJAZ1
RNA appears to arise from physiologically regulated trans-splicing between precursor messenger RNAs for
JAZF1
and
JJAZ1
. The chimeric RNA and protein are identical to those produced from a gene fusion found in human endometrial stromal tumors. These observations suggest that certain gene fusions may be pro-neoplastic owing to constitutive expression of chimeric gene products normally generated by trans-splicing of RNAs in developing tissues.
TRANSVERSALLY BIHARMONIC MAPS BETWEEN FOLIATED RIEMANNIAN MANIFOLDS
Authors: CHIANG YUAN-JEN , WOLAK ROBERT A.
Published: September 2008

We generalize the notions of transversally harmonic maps between foliated Riemannian manifolds into transversally biharmonic maps. We show that a transversally biharmonic map into a foliated manifold of non-positive transverse curvature is transversally harmonic. Then we construct examples of transversally biharmonic non-harmonic maps into foliated manifolds of positive transverse curvature. We also prove that if f is a stable transversally biharmonic map into a foliated manifold of positive constant transverse sectional curvature and f satisfies the transverse conservation law, then f is a transversally harmonic map.
IMPROVING THE EFFECTIVENESS OF KNOWLEDGE BASED RECOMMENDER SYSTEMS USING INCOMPLETE LINGUISTIC PREFERENCE RELATIONS
Authors: MARTÍNEZT LUIS , PÉREZ LUIS G. , BARRANCO MANUEL , ESPINILLA MACARENA
Published: September 2008

In the e-commerce arena new methods and tools have been recently developed to improve and customize the e-commerce web sites, according to users' necessities and preferences, that are usually vague and uncertain. The most successful tool in this field has been the Recommender Systems. Their aim is to assist e-shops customers to find out the most suitable products by using recommendations. Sometimes, these systems face situations where there is a lack of information or the information is vague or imprecise that yield unsuccessful results. Although several solutions have been proposed, they still present some limitations. In this paper, we present a Knowledge-Based Recommender System that manages and models the uncertainty related to users' preferences by using linguistic information. This system will overcome the problem of lack of information by computing recommendations through completing incomplete linguistic preference relations provided by the users.
BIFURCATIONS FOR QUASILINEAR ELLIPTIC EQUATIONS, II
Authors: LIU JIA-QUAN , WANG ZHI-QIANG
Published: September 2008

This paper is concerned with bifurcation solutions of quasilinear elliptic problems. Our results generalize some earlier work, in particular, a similar type of result found in [3] where an additional structural condition is required to be imposed and the result in [11] where bifurcations in terms of the radius of the solutions were considered.
FACTORIALITY AND NÉRON–SEVERI GROUPS
Authors: DI GENNARO VINCENZO , FRANCO DAVIDE
Published: September 2008

Let X ⊂ ℙ2m+1 be a projective variety with isolated singularities, complete intersection of a smooth hypersurface of degree k, with a smooth hypersurface F of degree n > k. Denote by NSm(F) and NSm(X) the mth Néron–Severi groups. We prove that if rkNSm(F) = 1, then rkNSm(X) = 1. Moreover, we prove that if [Formula: see text] is general and n > max {k, 2m + 1}, then the natural map NSm(X) ⊗ ℚ → NSm(F) ⊗ ℚ is surjective. When X is a threefold, we deduce that X is factorial if and only if rkNS2(F) = 1. This allows us to prove the existence of factorial threefolds with many singularities.
EVALUATING 3G LICENSING PATTERNS FOR AN INDIGENOUS STANDARD IN CHINA
Authors: HAN XUE , YU JIANG
Published: September 2008

With the largest wireless market in the world, China's selection of the appropriate 3G licensing patterns will have some crucial impacts on the landscape of telecommunication industry in China and other parts of the world. Under its obligations to the World Trade Organization, the Chinese government wishes to demonstrate a relatively structured and transparent 3G licensing process. Therefore, evaluation criteria in designing licensing patterns for the home-grown 3G standard should satisfy multiple goals to meet the requirements of the different stakeholders such as government, consumers, the potential operators, and domestic manufacturers. The surveys in methodology of Multi-Criteria Decision Making (MCDM) are conducted and the results reveal that the research methodology is applicable to the evaluation and policy-making process under the transitional context.
WIGNER FUNCTIONS, FRESNEL OPTICS, AND SYMPLECTIC CONNECTIONS ON PHASE SPACE
Authors: ISIDRO JOSÉ M.
Published: September 2008

We prove that Wigner functions contain a symplectic connection. The latter covariantizes the symplectic exterior derivative on phase space. We analyze the role played by this connection and introduce the notion of local symplectic covariance of quantum-mechanical states. This latter symmetry is at work in the Schrödinger equation on phase space.
ELLIPTIC CURVES, ALGEBRAIC GEOMETRY APPROACH IN GRAVITY THEORY AND UNIFORMIZATION OF MULTIVARIABLE CUBIC ALGEBRAIC EQUATIONS
Authors: DIMITROV BOGDAN G.
Published: September 2008

Based on the distinction between the covariant and contravariant metric tensor components in the framework of the affine geometry approach and the so called "gravitational theories with covariant and contravariant connection and metrics", it is shown that a wide variety of 3rd, 4th, 5th, 7th, 10th- degree algebraic equations exists in gravity theory. This is important in view of finding new solutions of the Einstein's equations, if they are treated as algebraic ones. Since the obtained cubic algebraic equations are multivariable, the standard algebraic geometry approach for parametrization of two-dimensional cubic equations with the elliptic Weierstrass function cannot be applied. Nevertheless, for a previously considered cubic equation for reparametrization invariance of the gravitational Lagrangian and on the base of a newly introduced notion of "embedded sequence of cubic algebraic equations", it is demonstrated that in the multivariable case such a parametrization is also possible, but with complicated irrational and non-elliptic functions. After finding the solutions of a system of first-order nonlinear differential equations, these parametrization functions can be considered also as uniformization ones (depending only on the complex uniformization variable z) for the initial multivariable cubic equation.
SOME TYPES OF DYNAMICAL 3-DIMENSIONAL BRAID
Authors: EL-GHOUL M. , AL-SHAMIRI M. M.
Published: September 2008

In this article we introduce the dynamical 3-dimensional braid and its braid group, and we introduce the deformation retract of dynamical 3-dimensional braid. The limit of all types of dynamics is described.
Small for Gestational Age Children without Early Catch-Up Growth: Spontaneous Growth and Prediction of Height at 8 Years
Authors: de Ridder Maria A.J. , Engels Melanie A.M.J. , Stijnen Theo , Hokken-Koelega Anita C.S.
Published: September 2008

Background/Aim: About 10–15% of children born small for gestational age (SGA) have at the age of 2 years a height standard deviation score (HSDS2y) still below –2. There is no model to predict which children will catch up in height after 2 years of age. The aim of this study was to determine the percentage of children with catch-up growth to a normal height after the age of 2 years and to develop a prediction model for growth after that age. Methods: In a cohort of 724 SGA children, the percentage of children with HSDS above –2 at 8 years of age was determined. In data of 97 children with HSDS2y below –2, a prediction model was developed for growth between 2 and 8 years. Results: Thirty-nine percent of children with HSDS2y below –2 reached an HSDSabove –2 between 2 and 8 years (6% of the total group). Determinants of growth after age 2 years, all with a positive influence, were the difference between target height SDS and HSDS2y, change in height SDS during first 2 years of life, female gender and multiple birth. Conclusions: Catch-up growth to a normal height occurred in 91% of SGA children, in 6% between 2 and 8 years of age. The difference between target height SDS and HSDS2y was the most important determinant. The presented prediction model can identify children with low or high probability of catch-up growth after the age of 2 years. This may assist to determine which children require medical follow-up.
Combined Growth Hormone-Releasing Hormone and Growth Hormone-Releasing Peptide-6 Test for the Evaluation of Growth Hormone Secretion in Children with Growth Hormone Deficiency and Growth Hormone Neurosecretory Dysfunction
Authors: Spiliotis Bessie E. , Papadimitriou Dimitrios T. , Alexandrides Theodore K. , Karystianos Christoforos , Nikiforidis George , Vassilakos Pavlos , Beratis Nicholas G. , Casanueva Felipe F.
Published: September 2008

Background: The combined growth hormone-releasing hormone and growth hormone-releasing peptide-6 (GHRH + GHRP-6) test is most potent in evaluating GH secretion. Aims: To assess its capability in children with GH deficiency and low spontaneous GH secretion (GH neurosecretory dysfunction). Methods: 35 children with GH <10 µg/l after levo-dopa/clonidine (GHD), 15 with normal provocative tests but abnormal 24-hour spontaneous GH secretion (GHND), and 20 controls (C) were given 1 µg/kg of GHRH and GHRP-6 i.v. and GH (µg/l) was measured at –15, 0, 5, 10, 15, 30, 45 and 60 min. Results: Six were nonresponders to the combined test, with significantly lower peak GH 20.7 (7.8–31.8) than C and the rest of the patients (responders). Peak GH was similar between prepubertal (PP) controls 167 ± 88, GHD 202 ± 110 and GHND 155 ± 83. Pubertal (P) controls had higher peak GH 328 ± 149 than P-GHD 203 ± 105 and P-GHND 186 ± 105. While P-C had higher peak GH than PP-C, PP and P children had similar responses within the GHD and GHND groups. Conclusions: The GHRH + GHRP-6 test detects children with severe GH insufficiency. Patients with GHD respond similarly to those with GHND, indicating a possible hypothalamic GH neuroregulatory dysfunction in GHD. Responders to the combined test may be eligible for treatment with a synthetic GH secretagogue.
Sleep-Disordered Breathing and Proteinuria in Overweight and Obese Children and Adolescents
Authors: Verhulst S.L. , Van Hoeck K. , Schrauwen N. , Haentjens D. , Rooman R. , Van Gaal L. , De Backer W. , Desager K.N.
Published: September 2008

Objectives: To assess whether sleep-disordered breathing (SDB) in overweight children and adolescents has an additional effect on the spectrum of urinary albumin to protein loss, as markers of early kidney dysfunction. Methods: Prospective study in a clinical sample of overweight children and adolescents. Each subject underwent anthropometry, blood sampling, oral glucose tolerance test and polysomnography. From a 24-hour urine collection, albumin excretion rate and total urinary protein to creatinine ratio (UPCR) were calculated. Results: 94 nondiabetic subjects were included (mean age = 11.0 ± 2.5, 42 boys). Average BMI z-score was 2.25 ± 0.47 (26 overweight subjects and 68 obese subjects). There was no difference in albumin excretion rate or UPCR between subjects with and without SDB. None of the SDB parameters correlated with the transformed albumin excretion rate or UPCR. Albumin excretion rate significantly correlated with fasting insulin and C-peptide and with post-challenge glucose, insulin and C-peptide levels, while UPCR correlated with fasting and post-challenge C-peptide levels. Multiple regression indicated that post-challenge glucose levels were the most important predictors of albumin excretion rate. Conclusion: Insulin resistance, and not SDB, was associated with increased levels of albuminuria, indicating early renal dysfunction, in this clinical sample of overweight children and adolescents.
Effects of Dietary Onion (Allium cepa L.) in a High-Fat Diet Streptozotocin-Induced Diabetes Rodent Model
Authors: Islam M. Shahidul , Choi Haymie , Loots Du Toit
Published: September 2008

Background/Aims: The present study was conducted to investigate the effects of two dietary doses of freeze-dried onion powder on diabetes-related symptoms in a high-fat (HF) diet streptozotocin (STZ)-induced diabetes rat model. Methods: Five-week-old male Sprague-Dawley rats were fed a HF diet for 2 weeks and then randomly divided into 4 groups as follows: HF control (HFC), diabetic control (DBC), onion low (ONL; 0.5%) and onion high (ONH; 2.0%). Diabetes was induced by an intraperitoneal injection of STZ (40 mg/kg body weight) in all groups except the HFC group. Results: After 4 weeks on the experimental diets, fasting blood glucose levels for both onion-fed groups were higher than in the DBC and HFC groups, albeit only significantly so (p < 0.05) in the ONL group. Serum insulin concentrations and insulin resistance were dose-dependently increased (however, not significantly so) in the onion-fed groups compared to the DBC group. Pancreatic β-cell function and liver glycogen concentrations were nonsignificantly higher in the DBC and ONH groups compared to the ONL group. Additionally, the ONH group had significantly higher lipid concentrations (except for high-density lipoprotein cholesterol) compared to all other groups. The ONL group showed a similar hyperlipidemic trend, however to a lesser extent, with only triglycerides significantly differing from those of the DBC and HFC groups. Conclusion: The results suggest that the HF onion diet may increase insulin secretion and consequently insulin resistance in a dose-dependent manner, resulting in a worsened hyperglycemic and hyperlipidemic diabetic state. We conclude that higher dietary fat may impair the antidiabetic effects of dietary onion intake as has been previously reported.
Temporal Changes in Anthropometric Parameters and Lipid Profile according to Body Mass Index among an Adult Iranian Urban Population
Authors: Bozorgmanesh Mohammad Reza , Hadaegh Farzad , Padyab Mojgan , Mehrabi Yadollah , Azizi Fereidoun
Published: September 2008

Aims: To examine changes in anthropometric parameters and lipid profiles over a period of 3.6 years in an Iranian adult population according to body mass index (BMI) groups. Methods: Between 1998 and 2001 (phase 1) and 2002 and 2005 (phase 2), 5,618 nondiabetic Iranian adults aged ≧20 years were examined. Analysis of covariance was used to delineate trends in anthropometric parameters as well as total and low- and high-density lipoprotein cholesterol (TC, LDL-C and HDL-C, respectively) across BMI groups. Results: Although BMI increased in women, this increase was not significant in obese persons. Among the men, however, a significant increase in BMI was observed only in lean persons. Waist circumference (WC) increased across all BMI groups in both sexes. A significant decrease was observed in TC [men: –0.83 mmol/l, 95% confidence interval (CI) –1.27 to –0.40; women: –0.78 mmol/l, CI –0.97 to –0.60] and LDL-C (men: –0.63 mmol/l, CI –1.13 to –0.13; women: –0.51 mmol/l, CI –0.78 to –0.24). A significant decrease in mean HDL-C was observed only among men (–0.09 mmol/l, CI –0.13 to –0.04), with no difference among BMI groups (p = 0.3). There were no significant decreases in TC/HDL-C and LDL-C/HDL-C ratios in men or women. Conclusions: Despite an increase in WC, favorable trends were observed in TC and LDL-C levels. The favorable trend in TC levels was counterbalanced by changes in HDL-C, as reflected by the absence of a significant decrease in TC/HDL-C or LDL-C/HDL-C.
Improvement in the Plasma Omega-3 Index by the Use of a Fish Oil-Enriched Spread
Authors: De Groote Guy , De Laporte André , Dhondt Goedele , Christophe Armand
Published: September 2008

Background: The main aim of this pilot study was to determine whether the omega-3 status can be improved by the use of a fish oil-enriched spread in a regular diet. Methods: The study started with an open arm where the participants consumed their regular diets followed by a randomized placebo-controlled arm with the inclusion of a spread which was either fish oil enriched or not (control). After each period,the fatty acid composition of red blood cell (RBC) and plasma phospholipids was determined by standard procedures and the sum of eicosapentaenoic and docosahexaenoic acid calculated. t tests were performed to calculate the significance. The first-order linear model was used to calculate correlations between selected parameters. Results: When the patients were on their usual diets, a strong correlation was found between the omega-3 index based on RBCs and plasma.In the group consuming the fish oil-enriched spread, the omega-3 index based on both RBCs and plasma was significantly higher after 3 weeks of intervention. This was not the case after intervention with the control spread. Conclusion: Inclusion of reasonable amounts of a fish oil-enriched spread in an otherwise regular diet can be sufficient for obtaining a significant increase in omega-3 index.
Targeted Minute Ventilation and Tidal Volume in an Animal Model of Acute Changes in Lung Mechanics and Episodes of Hypoxemia
Authors: Claure Nelson , Suguihara Cleide , Peng Jinghong , Hehre Dorothy , D’Ugard Carmen , Bancalari Eduardo
Published: September 2008

Background: Acute episodes of hypoxemia in ventilated preterm infants are triggered by changes in ventilation, lung volume (LV) and respiratory system compliance (CRS) that are not prevented by conventional synchronized intermittent mandatory ventilation (SIMV). Objective: To assess in a rabbit model of episodic hypoxemia the individual and combined efficacy of targeted tidal volume (VT) and minute ventilation (V’E) by automatic adjustment of peak inspiratory pressure (PIP) and ventilator rate, respectively. Methods: Six young New Zealand white rabbits were ventilated with SIMV, targeted VT, targeted V’E, and combined targeted V’E + VT in random sequence. Hypoxemia episodes were induced by apnea alone or by apnea combined with a reduction in LV and CRS. Apnea was induced by a bolus of propofol. The reduction in LV and CRS was induced by chest compression with a cuff. PaO2 and PaCO2 were measured continuously by an indwelling arterial electrode. Results: During SIMV, apnea caused a decrease in ventilation and PaO2. This was attenuated during targeted V’E and targeted V’E + VT. Apnea plus a reduction in LV and CRS caused a greater decrease in ventilation and PaO2 during SIMV. These changes were attenuated during targeted VT and targeted V’E. The attenuation was more pronounced during targeted V’E + VT. Conclusion: In this animal model, targeted V’E was effective in reducing hypoxemia caused by apnea. When apnea was accompanied by a reduction in LV and CRS, the combined adjustment of PIP and ventilator rate was more effective than each individually. This combined strategy may be effective in ameliorating acute episodes of hypoxemia in preterm infants but this remains to be proven.
Initiation of Glucose-Based Peritoneal Dialysis Is Associated with Increased Prevalence of Metabolic Syndrome in Non-Diabetic Patients with End-Stage Renal Disease
Authors: Jiang Na , Qian Jiaqi , Lin Aiwu , Lindholm Bengt , Axelsson Jonas , Yao Qiang
Published: September 2008

Background: Glucose-based peritoneal dialysis (PD) is the original PD form. However, glucose uptake from the peritoneal cavity may contribute to dysmetabolism. Methods: We retrospectively assessed metabolic syndrome (MS) and its components in 195 non-diabetic incident PD patients at baseline and after 34.3 (20.5–60.0) months of PD. MS was defined according to the Adult Treatment Panel III criteria. Results: While 22.1% of the patients met MS criteria at baseline, 69.2% (p < 0.01) exhibited MS during PD. MS burden increased significantly after PD (p < 0.01). The disorder BMI and lipids, and MS components number, correlated with peritoneal glucose exposure and PD duration (p < 0.05). In Cox analysis, age, BMI, triglyceride, C-reactive protein (CRP) and glucose exposure were all independently associated with MS development. Conclusions: PD commencement in end-stage renal disease patients was associated with an increased MS prevalence. High glucose exposure and long PD duration were associated with MS existence, along with old age, high BMI, triglyceride and CRP.
Evaluation of Killing Kinetics of Anti-Tuberculosis Drugs on Mycobacterium tuberculosis Using a Bacteriophage-Based Assay
Authors: Marcel Nimi , Nahta Ajay , Balganesh Meenakshi
Published: September 2008

Background: Killing kinetics studies on Mycobacterium tuberculosis are labour intensive and time consuming since it takes nearly 6–7 weeks to get the data from an experiment. A modified protocol is required to increase the throughput and expedite the results. Methods: The killing kinetics of frontline drugs used for the treatment of tuberculosis was studied using 24-well plates and 2 methods of enumeration of survivors of M. tuberculosis following drug exposure, namely conventional plating (CFU) and a phage-based assay (plaque-forming units) using mycobacteriophage D29. Results: The use of 24-well plates enabled in reducing the volume of the compound required for the studies and the phage-based enumeration speeded up the readout and compared well with the CFU-based enumeration. Conclusion: These results were in agreement with the earlier findings reported with respect to rifampicin, isoniazid and moxifloxacin. Also, this study shows for the first time the concentration-dependent killing of streptomycin, the time-dependent killing of ethambutol and the profiling of an experimental anti-mycobacterial compound by these 2 methods.
Methotrexate-Loaded Polymethylmethacrylate Bone Cement for Local Bone Metastasis Therapy: Pilot Animal Study in the Rabbit Patellar Groove
Authors: Draenert F.G. , Draenert K.
Published: September 2008

Local chemotherapy is an option in bone metastasis treatment. On the other hand, evaluation of side effects on bone is a difficult issue in drug development and biomaterials research. Most animal models to date are inappropriate or not feasible. Rabbits are an alternative to other bigger mammals and have an appropriate bone structure compared to rats and mice. The patellar groove model of the rabbit offers a standardized and sensitive model to evaluate bone-compromising drug effects. We tested the system with a reproducible polymethacrylate implant as carrier and loaded this system with methotrexate. Three methotrexate concentrations were used in the test samples (250 mg, 1 g and 4 g per 40 g polymethacrylate bone cement; 2 per group) for a descriptive histology approach. Eight German giant rabbits were operated on both knees and received test and control implants in a randomized manner in this bilateral study design. The histological results after 35 days were convincing, encouraging the use in preclinical drug development and biomaterials research and warranting further development of this metastasis treatment approach.
Oxidative Stress Mediates Protein Kinase C Activation and Advanced Glycation End Product Formation in a Mesangial Cell Model of Diabetes and High Protein Diet
Authors: Tuttle Katherine R. , Anderberg Robert J. , Cooney Sheryl K. , Meek Rick L.
Published: September 2008

Background/Aims: High levels of glucose and/or amino acids increase advanced glycation end products (AGE) and activate protein kinase C (PKC), a key signal for injury in mesangial cells. The aim was to determine whether oxidative stress mediates bidirectional interactions between AGE and PKC (‘cross-activation’) in this model. Methods: Rat mesangial cells were examined after 48 h of exposure to: high glucose (30.5 mM), increased amino acids designed to resemble a protein meal, the combination of both conditions, and control. Cells were treated with antioxidants (vitamin E, α-lipoic acid, N-acetylcysteine, apocynin, doses based on suppression of reactive oxygen species), PKC inhibitors (calphostin C orPLY379196, 100 nM), or AGE inhibitors (aminoguanidine or pyridoxamine 0.5 mM). Results: Carboxymethyllysine, an AGE marker, increased twofold in mesangial cells exposed to the experimental conditions. Antioxidants and PKC inhibition prevented carboxymethyllysine increases. Likewise, antioxidants and AGE inhibition prevented PKC activation. Inhibition of carboxymethyllysine increases and PKC activation by apocynin indicates a primary role for NADPH oxidase in producing oxidative stress. Induction of transforming growth factor-β1 and fibronectin was inhibited by antioxidants and inhibitors of PKC and AGE. Conclusions: Oxidative stress mediated cross-activation between PKC and AGE in this mesangial cell model of diabetes and high protein diet.PKC may amplify cellular injury by promoting AGE accumulation.
Down’s Syndrome Associated with a Familial (21q—;22q+) Translocation
Authors: Cohen M.M. , Davidson R.G.
Published: September 2008

A family possessing two mongoloid sibs and three balanced heterozygous carriers for a non-centric translocation between the long arm of a No. 21 and long arm of a No. 22 chromosome, yielding a medium-size acrocentric marker, is presented. In addition, the mother of the propositi, her brother and mother possessed a small, satellited centric fragment which is presumed to be the reciprocal element of the translocation.
Crossing-Over and the Centromere
Authors: Cuevas-Sosa A.
Published: September 2008

Experiments with human lymphocytes and H.Ep.2 human neoplastic cells treated with tritiated thymidine yielded evidence which suggests that sister chromatid crossing-over may occur in the centromere. As a result of this study a possible mechanism of isochromosome formation is postulated.
The Content of Deoxyribonucleic Acid in Individual Polytene Chromosomes of Chironomus tentans
Authors: Daneholt B. , Edström J.-E.
Published: September 2008

The DNA content was measured in individual polytene chromosomes of Chironomus tentans belonging to the two last classes of replication. The following results were obtained: (1) The DNA contents of the chromosomes of the higher size class were about twice that of the lower class, which indicates that most or all of the chromatids carry out one replication between these two stages. (2) The DNA contents were found to be correlated to chromosome length, and the average amount of DNA per band was similar in the four chromosome pairs. (3) The probable DNA value per chromatid set was determined, from which the average DNA value per chromomere could be estimated to 10-16 g. This value corresponds to about 105 base pairs, suggesting either that the bands represent operational units of great complexity or that a large part of DNA is non-functional in an informational sense.
Influence of Nuclear Selection Criteria on Sex Chromatin Frequency in Oral Mucosa Cells of Newborn Females
Authors: Hsu Lillian Y.F. , Klinger H.P. , Weiss Jane , Hoffman R. , Pyne Dorothy , Rubin H.
Published: September 2008

The frequency of sex chromatin positive nuclei was determined in oral mucosa smears of 47 newborn females during their first three days of life. In contrast to some previous reports, the lowest sex chromatin frequency found was 21 %, and the means for days 1, 2 and 3 were 33.5 %, 34.1 %and 37.0% respectively. The mean value for day 3 was nearly identical with that obtained for six normal adult women. The slight increase over the three days was statistically significant, although the magnitude of this increase was much less than that reported by other workers. By determining the ratio of nuclei with morphologic characteristics suitable for sex chromatin determinations to those which do not meet minimal morphologic criteria, it was possible to show that there are more unsuitable, probably degenerating nuclei present shortly after birth than later on. This factor may explain the low initial frequencies other workers have reported. It may be difficult to differentiate some degenerated nuclei from viable nuclei. The former may be ‘false negatives’, and their inadvertent inclusion in a count would decrease the frequency of sex chromatin positive nuclei. This argument is supported by our findings on sex chromatin counts performed in the absence of selection criteria. Smears with many unsuitable nuclei had a much lower frequency than those with few unsuitable nuclei. This bias can be reduced, if not eliminated, when stringent selection criteria are applied. With standard criteria, reproducible and reliable sex chromatin frequency determinations can be made on oral smears of newborn infants.
Matrix Gla-protein: The calcification inhibitor in need of vitamin K
Authors: Cranenburg Ellen C. M. , Vermeer Cees , Schurgers Leon J.
Published: September 2008

Among the proteins involved in vascular calcium metabolism, the vitamin K-dependent matrix Gla-protein (MGP) plays a dominant role. Although on a molecular level its mechanism of action is not completely understood, it is generally accepted that MGP is a potent inhibitor of arterial calcification. Its pivotal importance for vascular health is demonstrated by the fact that there seems to be no effective alternative mechanism for calcification inhibition in the vasculature. An optimal vitamin K intake is therefore important to maintain the risk and rate of calcification as low as possible. With the aid of conformation-specific antibodies MGP species in both tissue and the circulation have been detected in the healthy population, and significant differences were found in patients with cardiovascular disease (CVD). Using ELISA-based assays, uncarboxylated MGP (ucMGP) was demonstrated to be a promising biomarker for cardiovascular calcification detection. These assays may have potential value for identifying patients as well as apparently healthy subjects at high risk for CVD and/or cardiovascular calcification and for monitoring the treatment of CVD and vascular calcification.
Anti-heparin/platelet factor 4 antibody optical density values and the confirmatory procedure in the diagnosis of heparin-induced thrombocytopenia
Authors: Perry Stephanie L. , Ortel Thomas L. , Whitlatch Nicole L.
Published: September 2008

Laboratory testing for heparin-induced thrombocytopenia (HIT) includes the highly sensitive, though less specific, heparin/ platelet factor 4 (PF4) ELISA. A confirmatory test with excess heparin is routinely performed on positive ELISA results to improve test specificity; the significance of a negative confirmatory result is unknown. The aim was firstly to evaluate the clinical utility of the PF4 ELISA confirmatory assay, secondly to examine the relationship between ELISA optical density (OD) value and clinical diagnosis of HIT, and thirdly to assess current practice at a tertiary care medical centre regarding patients with anti-heparin/PF4 antibodies. Patients with anti-heparin/PF4 antibodies detected by commercial ELISA during 2005 were identified. A confirmatory test was performed on positive ELISA results. Patients were labeled confirmatory positive (confirm+) or confirmatory negative (confirm−). Patients were classified as HIT+ (met criteria for HIT), HIT? (HIT possible), and HIT- (did not meet criteria for HIT) utilizing ACCP guidelines. One hundred fifteen patients with anti-heparin/PF4 antibodies were identified. Ninety-eight patients were confirm+;17 were confirm−. The majority of confirm+ patients were HIT+ or HIT?(72%);the majority of confirm− patients were HIT− (81%). Patients who were HIT+/confirm+ had higher ELISA OD values than patients who were HIT?/confirm+ or HIT− /confirm+ (p=0.031, p=0.001). Two confirm− patients were HIT+, one was HIT?; all had high ELISA OD values. Although confirm+ status correlated with clinical HIT, the confirmatory procedure misclassified some patients by yielding a confirm− result despite clinical HIT with high ELISA OD values. Future studies should compare higher ELISA OD values with the confirmatory procedure as strategies to improve ELISA diagnostic specificity for HIT.
Generation and biochemical characterization of glycoPEGylated factor VIIa derivatives
Authors: Østergaard Henrik , Bayer Robert J. , Kalo Matt S. , Kinealy Kyle , Holm Pernille K. , Sørensen Brit B. , Zopf David , Bjørn Søren E. , Stennicke Henning R.
Published: September 2008

Prophylaxis with 2–4 times weekly dosing of factor (F)VIII or FIX is established as an efficacious and safe treatment in haemophilia. Although prophylaxis is not readily available for the inhibitor patient,recent studies have demonstrated a reduction in bleeding episodes in inhibitor patients treated with daily infusions of FVIIa. In order to develop a treatment option comparable to prophylaxis with FVIII or FIX we looked to PEGylation which is an established method for prolonging the circulatory half-life of proteins. However, due to the numerous interactions of FVIIa with the cell surface,TF,FIX and FX there are limited options for unspecific chemical modification of FVIIa without loss of activity. Consequently, we explored the GlycoPEGylation™ technology for selective PEGylation of the two N-glycans in the FVIIa light chain and protease domain to generate seven specifically modified derivatives with PEG groups ranging from 2 to 40 kDa. These derivatives were evaluated in vitro for their ability to interact with small synthetic substrates as well as key molecules relevant to function in the coagulation pathway. The results demonstrate that modification of FVIIa using glycoPEGylation has only a very limited effect on the hydrolysis S-2288 and FX activation. However, the modification does to some extend alter the ability of FVIIa to interact with TF and more importantly, reduces the rate of ATIII inhibition by up to 50% which could allow for an extended active half-life in circulation.
Prospective validation of the Pulmonary Embolism Severity Index
Authors: Gal Grégoire , Fine Michael J. , Roy Pierre-Marie , Sanchez Olivier , Verschuren Franck , Cornuz Jacques , Meyer Guy , Perrier Arnaud , Righini Marc , Aujesky Drahomir , Donzé Jacques
Published: September 2008

Practice guidelines recommend outpatient care for selected patients with non-massive pulmonary embolism (PE), but fail to specify how these low-risk patients should be identified. Using data from U.S. patients, we previously derived the Pulmonary Embolism Severity Index (PESI), a prediction rule that risk stratifies patients with PE. We sought to validate the PESI in a European patient cohort. We prospectively validated the PESI in patients with PE diagnosed at six emergency departments in three European countries. We used baseline data for the rule’s 11 prognostic variables to stratify patients into five risk classes (I-V) of increasing probability of mortality. The outcome was overall mortality at 90 days after presentation.To assess the accuracy of the PESI to predict mortality, we estimated the sensitivity, specificity, and predictive values for low- (risk classes I/II) versus higher- risk patients (risk classes III-V), and the discriminatory power using the area under the receiver operating characteristic (ROC) curve. Among 357 patients with PE, overall mortality was 5.9%, ranging from 0% in class I to 17.9% in class V. The 186 (52%) low-risk patients had an overall mortality of 1.1% (95% confidence interval [CI]: 0.1–3.8%) compared to 11.1% (95% CI: 6.8–16.8%) in the 171 (48%) higher- risk patients. The PESI had a high sensitivity (91%,95% CI: 71–97%) and a negative predictive value (99%, 95% CI: 96–100%) for predicting mortality. The area under the ROC curve was 0.78 (95% CI:0.70–0.86). The PESI reliably identifies patients with PE who are at low risk of death and who are potential candidates for outpatient care. The PESI may help physicians make more rational decisions about hospitalization for patients with PE.
Omics meets hypothesis-driven research
Authors: Tissot Jean-Daniel , Farmer Pierre , Mariotti Agnese , Rüegg Curzio
Published: September 2008

The emergence of omics technologies allowing the global analysis of a given biological or molecular system, rather than the study of its individual components,has revolutionized biomedical research, including cardiovascular medicine research in the past decade. These developments raised the prospect that classical,hypothesis-driven,single gene-based approaches may soon become obsolete. The experience accumulated so far, however, indicates that omic technologies only represent tools similar to those classically used by scientists in the past and nowadays, to make hypothesis and build models, with the main difference that they generate large amounts of unbiased information.Thus,omics and classical hypothesis-driven research are rather complementary approaches with the potential to effectively synergize to boost research in many fields, including cardiovascular medicine. In this article we discuss some general aspects of omics approaches, and review contributions in three areas of vascular biology, thrombosis and haemostasis, atherosclerosis and angiogenesis, in which omics approaches have already been applied (vasculomics).
Uncertainties in the Diagnosis and Treatment of Pulmonary Arterial Hypertension
Authors: Ghofrani Hossein A. , Wilkins Martin W. , Rich Stuart
Published: September 2008

The availability of new treatments for patients with pulmonary arterial hypertension has increased awareness and interest in the medical community for pulmonary vascular diseases in general. Many uncertainties exist, however, regarding the diagnosis and treatment of patients with pulmonary arterial hypertension that are particularly pertinent for the management of patients with idiopathic pulmonary arterial hypertension and pulmonary hypertension associated with underlying diseases. This review highlights controversial issues around the definition and diagnosis of pulmonary hypertension, the interpretation of hemodynamic variables, and the interpretation of clinical responsiveness to chronic therapies. In addition, we propose guidelines applicable to the conduct of new therapeutic trials in pulmonary arterial hypertension, which aim to provide greater confidence in the efficacy and safety of new treatments currently under development.
Regulating and Resolving Public Sector Disputes in Canada
Authors: Rose Joseph B.
Published: September 2008

This article discusses three broad approaches that have been adopted for the regulation and resolution of public sector strikes in Canada and provides a review of empirical and other research findings on public sector disputes procedures. This is followed by an assessment of the effectiveness of these approaches based on their ability to: (1) provide for the continuance of essential services; (2) achieve timely settlements (e.g. collective bargaining efficiency); (3) foster voluntary and peaceful settlements; and (4) promote acceptable outcomes. The article concludes that the reality is public sector strikes are inevitable, strike bans do not eliminate strikes and no dispute resolution model is totally effective.