bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study of Demolding Properties on Stereolithography Tooling
Authors: An Chao-Chyun , Chen Ren-Haw
Published: August 2007

Direct tooling using stereolithography (SL) photopolymer has been developed as rapid tooling for short-run injection molds. However, the tool strength, thermal conductivity, and erosion resistance of SL mold are lower than that of the conventional metal mold. Previous study has showed that the tool life was limited under 200 shots and tool damage often occurs during part ejection. In this paper, experimental data from a demolding properties test are presented and discussed. The experiments were performed using various cooling time, hold pressure, and mold temperature. The experimental data were analyzed by measuring demolding force and surface roughness to evaluate tool life and failure mechanism in order to obtain a working range for the process parameters. The test result shows that the demolding force has close relation with cooling time and mold temperature.
Dynamic Hybrid Modeling of the Vertical Z Axis in a High-Speed Machining Center: Towards Virtual Machining
Authors: Tani Giovanni , Bedini Raffaele , Fortunato Alessandro , Mantega Claudio
Published: August 2007

This paper describes the modeling and simulation of the Z axis of a five axis machining center for high-speed milling. The axis consists of a mechanical structure: machine head and electro-mandrel, a CNC system interfaced with the feed drive, and a pneumatic system to compensate for the weight of the vertical machine head. These subsystems were studied and modeled by means of: (1) finite element method modeling of the mechanical structure; (2) a concentrated parameter model of the kinematics of the axis; (3) a set of algebraic and logical relations to represent the loop CNC-Z feed drive; (4) an equation set to represent the functioning of the pneumatic system; and (5) a specific analytical model of the friction phenomena occurring between sliding and rotating mechanical components. These modeled subsystems were integrated to represent the dynamic behavior of the entire Z axis. The model was translated in a computer simulation package and the validation of the model was made possible by comparing the outputs of simulation runs with the records of experimental tests on the machining center. The firm which promoted and financed the research now has a virtual tool to design improved machine-tool versions with respect to present models, designed by traditional tools.
Investigation of Deformation Size Effects During Microextrusion
Authors: Parasiz Sunal Ahmet , Kinsey Brad , Krishnan Neil , Cao Jian , Li Ming
Published: August 2007

Microextrusion has recently emerged as a feasible manufacturing process to fabricate metallic micropins having characteristic dimensions on the order of less <1mm. At this length scale, the deformation of the workpiece is dominated by the so-called size effects, e.g., material property and frictional behavior variations at small length scales. In extrusion experiments performed to produce submillimeter-sized pins having a base diameter of 0.76mm and an extruded diameter of 0.57mm, the extruded pins exhibited a curving tendency when a workpiece with a relatively coarse grain size of 211μm was used. This phenomenon was not observed when workpieces with a finer grain size of 32μm were used. In this paper, results from microhardness tests and microstructure analyses for both grain sizes are presented to investigate this phenomenon and to characterize the deformation during microextrusion. The results obtained from this analysis show that as the grain size approaches the specimen feature size, the deformation characteristics of the extruded pins are dominated by the size and location of specific grains, leading to a nonuniform distribution of plastic strain and measured hardness and, thus, the curving tendency. Microhardness tests of the initial billet material and tensile test specimens are also presented as supplementary analyses.
Stream-of-Variation Modeling—Part I: A Generic Three-Dimensional Variation Model for Rigid-Body Assembly in Single Station Assembly Processes
Authors: Huang Wenzhen , Lin Jijun , Bezdecny Michelle , Kong Zhenyu , Ceglarek Dariusz
Published: August 2007

A stream-of-variation analysis (SOVA) model for three-dimensional (3D) rigid-body assemblies in a single station is developed. Both product and process information, such as part and fixture locating errors, are integrated in the model. The model represents a linear relationship of the variations between key product characteristics and key control characteristics. The generic modeling procedure and framework are provided, which involve: (1) an assembly graph (AG) to represent the kinematical constraints among parts and fixtures, (2) an unified method to transform all constraints (mating interface and fixture locators etc.) into a 3-2-1 locating scheme, and (3) a 3D rigid model for variation flow in a single-station process. The generality of the model is achieved by formulating all these constraints with an unified generalized fixture model. Thus, the model is able to accommodate various types of assemblies and provides a building block for complex multistation assembly model, in which the interstation interactions are taken into account. The model has been verified by using Monte Carlo simulation and a standardized industrial software. It provides the basis for variation control through tolerance design analysis, synthesis, and diagnosis in manufacturing systems.
Tool Temperature in Titanium Drilling
Authors: Li Rui , Shih Albert J.
Published: August 2007

The spatial and temporal distribution of tool temperature in drilling of commercially pure titanium is studied using the inverse heat transfer method. The chisel and cutting edges of a spiral point drill are treated as a series of elementary cutting tools. Using the oblique cutting analysis of the measured thrust force and torque, the forces and frictional heat generation on elementary cutting tools are calculated. Temperatures measured by thermocouples embedded on the drill flank face are used as the input for the inverse heat transfer analysis to calculate the heat partition factor between the drill and chip. The temperature distribution of the drill is solved by the finite element method and validated by experimental measurements with good agreement. For titanium drilling, the drill temperature is high. At 24.4 m/min and 73.2 m/min drill peripheral cutting speed, the peak temperature of the drill reaches 480°C and 1060°C, respectively, after 12.7 mm depth of drilling with 0.025 mm feed per cutting tooth. The steady increase of drill temperature versus drilling time is investigated.
Study of the Size Effects and Friction Conditions in Microextrusion—Part II: Size Effect in Dynamic Friction for Brass-Steel Pairs
Authors: Mori Lapo F. , Krishnan Neil , Cao Jian , Espinosa Horacio D.
Published: August 2007

In this paper, the results of experiments conducted to investigate the friction coefficient existing at a brass-steel interface are presented. The research discussed here is the second of a two-part study on the size effects in friction conditions that exist during microextrusion. In the regime of dimensions of the order of a few hundred microns, these size effects tend to play a significant role in affecting the characteristics of microforming processes. Experimental results presented in the previous companion paper have already shown that the friction conditions obtained from comparisons of experimental results and numerical models show a size effect related to the overall dimensions of the extruded part, assuming material response is homogeneous. Another interesting observation was made when extrusion experiments were performed to produce submillimeter sized pins. It was noted that pins fabricated from large grain-size material (211μm) showed a tendency to curve, whereas those fabricated from billets having a small grain size (32μm), did not show this tendency. In order to further investigate these phenomena, it was necessary to segregate the individual influences of material response and interfacial behavior on the microextrusion process, and therefore, a series of frictional experiments was conducted using a stored-energy Kolsky bar. The advantage of the Kolsky bar method is that it provides a direct measurement of the existing interfacial conditions and does not depend on material deformation behavior like other methods to measure friction. The method also provides both static and dynamic coefficients of friction, and these values could prove relevant for microextrusion tests performed at high strain rates. Tests were conducted using brass samples of a small grain size (32μm) and a large grain size (211μm) at low contact pressure (22MPa) and high contact pressure (250MPa) to see whether there was any change in the friction conditions due to these parameters. Another parameter that was varied was the area of contact. Static and dynamic coefficients of friction are reported for all the cases. The main conclusion of these experiments was that the friction coefficient did not show any significant dependence on the material grain size, interface pressure, or area of contact.
Stream-of-Variation (SOVA) Modeling II: A Generic 3D Variation Model for Rigid Body Assembly in Multistation Assembly Processes
Authors: Huang Wenzhen , Lin Jijun , Kong Zhenyu , Ceglarek Dariusz
Published: August 2007

A 3D rigid assembly modeling technique is developed for stream of variation analysis (SOVA) in multi-station processes. An assembly process is modeled as a spatial indexed state transition dynamic system. The model takes into account product and process factors such as: part-to-fixture, part-to-part, and inter-station interactions, which represent the influences coming from both tooling errors and part errors. The incorporation of the virtual fixture concept (Huang et al., Proc. of 2006 ASME MSEC) and inter-station interaction leads to the generic, unified SOVA model formulation. An automatic model generation technique is also developed for surmounting difficulties in modeling based on first principles. It enhances the applicability in modeling complex assemblies. The developed SOVA methodology outperforms the current simulation based techniques in computation efficiency, not only in forward analysis of complex assembly systems (tolerance analysis, sensitivity analysis), but it is also more powerful in backward analysis (tolerance synthesis and dimensional fault diagnosis). The model is validated using industrial case studies and series of simulations conducted using standardized industrial software (3DCS Analyst).
Synchrony Dynamics During Initiation, Failure, and Rescue of the Segmentation Clock
Authors: Riedel-Kruse Ingmar H. , Müller Claudia , Oates Andrew C.
Published: August 2007

The “segmentation clock” is thought to coordinate sequential segmentation of the body axis in vertebrate embryos. This clock comprises a multicellular genetic network of synchronized oscillators, coupled by intercellular Delta-Notch signaling. How this synchrony is established and how its loss determines the position of segmentation defects in Delta and Notch mutants are unknown. We analyzed the clock's synchrony dynamics by varying strength and timing of Notch coupling in zebra-fish embryos with techniques for quantitative perturbation of gene function. We developed a physical theory based on coupled phase oscillators explaining the observed onset and rescue of segmentation defects, the clock's robustness against developmental noise, and a critical point beyond which synchrony decays. We conclude that synchrony among these genetic oscillators can be established by simultaneous initiation and self-organization and that the segmentation defect position is determined by the difference between coupling strength and noise.
Multicolor Super-Resolution Imaging with Photo-Switchable Fluorescent Probes
Authors: Bates Mark , Huang Bo , Dempsey Graham T. , Zhuang Xiaowei
Published: August 2007

Recent advances in far-field optical nanoscopy have enabled fluorescence imaging with a spatial resolution of 20 to 50 nanometers. Multicolor super-resolution imaging, however, remains a challenging task. Here, we introduce a family of photo-switchable fluorescent probes and demonstrate multicolor stochastic optical reconstruction microscopy (STORM). Each probe consists of a photo-switchable “reporter” fluorophore that can be cycled between fluorescent and dark states, and an “activator” that facilitates photo-activation of the reporter. Combinatorial pairing of reporters and activators allows the creation of probes with many distinct colors. Iterative, color-specific activation of sparse subsets of these probes allows their localization with nanometer accuracy, enabling the construction of a super-resolution STORM image. Using this approach, we demonstrate multicolor imaging of DNA model samples and mammalian cells with 20- to 30-nanometer resolution. This technique will facilitate direct visualization of molecular interactions at the nanometer scale.
Commonly Used Antioxidant Botanicals: Active Constituents and Their Potential Role in Cardiovascular Illness
Authors: Wang Chong-Zhi , Mehendale Sangeeta R. , Yuan Chun-Su
Published: August 2007

Cardiovascular disease continues to be the leading cause of death in the US. Recent studies found that reactive oxygen species (ROS) have been incriminated in the pathogenesis of both acute and chronic heart diseas. Many botanicals possess antioxidant properties, and these herbal antioxidants may protect against cardiovascular diseases by contributing to the total antioxidant defense system of the human body. In this article, we reviewed the antioxidant components and properties of four putative antioxidant botanicals (i.e., grape seeds, green tea, Scutellaria baicalensis, and American ginseng), and their potential role in treating cardiovascular illness. The antioxidant activities of the herbal active constituents, and the relationship between their chemical structures and biological functions were also discussed. Further investigations are needed on the mechanisms of action of these botanicals as they affect salient cellular and molecular pathways involved in major diseases. Data obtained from future studies will have the potential for translation into practical benefits for human health.
Ganodermataceae: Natural Products and Their Related Pharmacological Functions
Authors: Zhou Xuanwei , Lin Juan , Yin Yizhou , Zhao Jingya , Sun Xiaofen , Tang Kexuan
Published: August 2007

The objective of this paper is to review the natural products and the pharmacological functions of Ganodermataceae family. Presently, studies on the bioactive components of Lingzhi are focused on polysaccharides and triterpenes/triterpenoids compounds. New Ganoderma polysaccharides, including their molecular weights, glycosyl residue compositions, glycosyl linkage and branches, are summarized in this paper. Also presented are new types of triterpenes and their characteristics from Lingzhi. Taking Ganoderma lucidum as an example, we reviewed its pharmacological functions in anti-tumor and immune-modulating activities for treating hypoglycemosis, hepatoprotection, and the effect on blood vessel system. Based on the advances in Lingzhi research in the past few decades, both G. lucidum and G. sinense are considered as the representative species of medicinal mushroom Lingzhi in China. Until 2001, G. tsugae was only advised to be used as the materials of the health products. The biologically-active components related to pharmacological functions of these three species were studied more than other Ganodermataceae family species; however, which have been used in less modern folk medicine.
Improvement of Sperm Production in Subfertile Boars byCordyceps militarisSupplement
Authors: Lin Wen-Hung , Tsai Ming-Ta , Chen Yuh-Shuen , Hou Rolis Chien-Wei , Hung Hsiao-Fang , Li Ching-Hsiao , Wang Hsin-Kai , Lai Min-Nan , Jeng Kee-Ching G.
Published: August 2007

Cordyceps species have been traditionally used for the enhancement of sexual function, however, there is few direct evidence to prove this. We investigated the spermatogenic effect of Cordyceps militaris (CM) by supplementation with CM mycelium to subfertile boars. Seventeen Duroc and 12 Landrace boars (29 to 40 months old) were selected to feed with regular diet (control groups, n = 8 and 6, respectively) or diet supplemented with CM mycelium (treatment groups, n = 9 and 6, respectively) for 2 months. Semen was collected once a week. The quality of fertile sperm (normally greater than 62% of motility and 70% of normal morphology) and the quantity (semen volume, and total sperm number) were compared in these boars. The result showed that sperm production was enhanced significantly at the end of first month ( p < 0.05), peaked at the second month ( p < 0.01) of supplementation with CM and was maintained for 2 weeks after stopping the treatment ( p < 0.01). Plasma cordycepin concentration was detected in boars supplemented with CM but not in the controls. More importantly, the percentages of motile sperm cells and sperm morphology were also improved significantly in most of treated boars during the second month of supplementation ( p < 0.01) and 2 weeks after the treatment ( p < 0.05) as compared to their initial values. These results indicate that supplementation with CM mycelium improves sperm quality and quantity in subfertile boars and may partly support the role of Cordyceps in sexual enhancement.
Anti-Osteoporosis Activity of Naringin in the Retinoic Acid-Induced Osteoporosis Model
Authors: Wei Min , Yang Zhonglin , Li Ping , Zhang Yabo , Sse Wing Cho
Published: August 2007

Isoflavonoids isolated from plants have been confirmed to fight osteoporosis and promote bone health. However, few studies have been conducted to describe the anti-osteoporosis activity of botanical flavonone. Based on the experimental outcomes, we demonstrated the ability of naringin to fight osteoporosis in vitro. We developed a retinoic acid-induced osteoporosis model of rats to assess whether naringin has similar bioactivity against osteoporosis in vitro. After a 14-day supplement of retinoic acid to induce osteoporosis, SD rats were administered naringin. A blood test showed that naringin-treated rats experienced significantly lower activity of serum alkaline phosphatase and had higher femur bone mineral density, compared to untreated rats. All three dosages of naringin improved the decrease in bone weight coefficient, the length and the diameter of the bone, the content of bone ash, calcium, and phosphorus content induced by retinoic acid. The data of histomorphological metrology of naringin groups showed no difference as compared to normal control rats. These outcomes suggest that naringin offer a potential in the management of osteoporosis in vitro.
Psoralea corylifoliaExtract Ameliorates Experimental Osteoporosis in Ovariectomized Rats
Authors: Tsai Meng-Hsiun , Huang G. Steven , Hung Yao-Ching , Bin Liu , Liao Lung-Te , Lin Li-Wei
Published: August 2007

We evaluated the protective effect of Psoralea corylifolia L. (PCL) extract on the ovariectomized (OVX) rat model. The biochemical markers of bone turnover, calcium metabolism, and calcium balance were examined. PCL extract (25 mg or 50 mg/kg body weight/day) was orally administrated to OVX rats for 3 months. PCL extract did not alter weight gain or uterus weight in OVX rats. PCL extract significantly increased serum Ca (calcium) levels ( p < 0.05, vs. OVX group) as well as decreased urinary Ca excretion ( p < 0.05 vs. OVX group) in OVX rats. The upregulation of serum osteocalcin level by ovariectomy was suppressed by treatment with PCL extract in rats ( p < 0.05, vs. OVX group). PCL extract increased bone mineral density at 50 mg/kg body weight/day in OVX rats ( p < 0.05, vs. OVX group). Our results indicate that orally administrated PCL extract can decrease urinary calcium excretion and decrease serum osteocalcin in OVX rats, resulting in positive effects on bone mineral density as well as bone formation. In conclusion, our studies showed that PCL might be a potential candidate for treatment of postmenopausal osteoporosis.
The Neuroprotective Effect of Picroside II from Hu-Huang-Lian against Oxidative Stress
Authors: Li Ting , Liu Jian-Wen , Zhang Xiao-Dong , Guo Ming-Chuan , Ji Guang
Published: August 2007

Picroside II is an active constituent extracted from the traditional Chinese medicine (TCM) Hu-Huang-Lian. To evaluate the neuroprotective effect of picroside II, PC12 cells were treated with glutamate in vitro and male ICR mice were treated with AlCl 3in vivo. Pre-treatment of PC12 cells with picroside II could enhance the cell viability and decrease the level of intracellular reactive oxygen species (ROS) induced by glutamate. By DNA fragmentation and flow cytometry assay, picroside II (1.2 mg/ml) significantly prevented glutamate-induced cell apoptosis. In the animal study, amnesia was induced in mice by AlCl 3 (100 mg/kg/d, i.v.). Pricroside II, at the dose of 20 and 40 mg/kg/d (i.g.), markedly ameliorated AlCl 3-induced learning and memory dysfunctions and attenuated AlCl 3-induced histological changes. This was associated with the significant increased superoxide dismutase (SOD) activity in the brain of experimental mice. All these results indicated that picroside II possessed the therapeutic potential in protecting against neurological injuries damaged by oxidative stress.
Effects of Hypocrellin A on Expression of Vascular Endothelial Growth Factor and Endothelin-1 in Human Umbilical Endothelial Cells
Authors: Dang Lei , Seale J. Paul , Qu Xianqin
Published: August 2007

Increased endothelin-1 (ET-1), vascular endothelial growth factor (VEGF) and activation of protein kinase C (PKC) are co-contributors to endothelial hyperpermeability in diabetes. Several lines of evidence have suggested a hypothesis that activation of specific PKC isoforms are the causative factor in ET-1 and VEGF mediated endothelial dysfunction. In the present study, we tested this hypothesis with hypocrellin A, a naturally occurring PKC inhibitor from a Chinese plant. Human umbilical vein endothelial cells (HUVECs) were incubated with 20 mM glucose in both the presence and absence of hypocrellin A, after which, the protein expression and release of VEGF and mRNA expression and release of ET-1 were measured. VEGF and ET-1 were released into the medium and expressions of VEGF protein and ET-1 mRNA were significantly increased in HUVECs incubated with 20 mM glucose. Hypocrellin A (150 nM) significantly decreased VEGF release (117 ± 3 vs. 180 ± 11 pg/mg, p < 0.05) and VEGF protein expression (from 130 ± 14% to 88 ± 18.5%, p < 0.05). ET-1 release was also reduced in hypocrellin A treated HUVECs (63.3 ± 9.9 vs. 75.2 ± 12.6 ng/mg). Hypocrellin A significantly reversed the effect of high glucose on ET-1 mRNA expression ( p < 0.05). The results revealed that PKC activation plays a pivotal role in VEGF and ET-1 mediated endothelial permeability. The naturally occurring compound hypocrellin A may be a potentially novel treatment for endothelial dysfunction in diabetes.
ORGANOMETALLIC SYNTHESIS OF NANOPARTICLES
Authors: AMIENS C. , CHAUDRET B.
Published: August 2007

Nanoparticles can be synthesized from metal-organic or organometallic precursors, either by classical thermal decomposition, ultrasound activation, photolysis as well as hydrogenation or hydrolysis reactions. The size, size distribution and more importantly surface state of these nanoparticles are much better controlled than when they are produced by chemical or electrochemical reduction of metal salts. Hence, metal or oxide nanoparticles can be obtained that are suitable for fundamental physics at the nanoscale, especially for magnetic studies. This is currently of particular interest as many applications require systems of still smaller sizes, the properties of which are not yet fully understood.
OXIDATION PROCESS OF Fe NANOPARTICLES
Authors: SIMEONIDIS K. , MOURDIKOUDIS S. , TSIAOUSSIS I. , FRANGIS N. , ANGELAKERIS M. , KALOGIROU O. , DELIMITIS A. , DENDRINOU-SAMARA C.
Published: August 2007

The natural oxidation process is studied in the case of 15 nm iron nanoparticles produced by the thermal decomposition of Fe(CO) 5. X-ray diffraction spectra of the nanoparticles at different timescales after exposure to air revealed the instant oxidation of iron and the formation of wüstite and magnetite. Wüstite mainly occupies the interior of nanoparticles, as evidenced by microscopy, but is slowly transformed to a spinel structure. The shape, the dispersion and the role of surfactant were investigated by conventional microscopy and Fourier Transformed-Infrared (FT-IR) spectroscopy. Magnetic hysteresis loops confirmed the expected variation of magnetic properties till the steady state.
A MONTE CARLO STUDY OF THE EXCHANGE BIAS EFFECTS IN MAGNETIC NANOPARTICLES WITH FERROMAGNETIC CORE/ANTIFERROMAGNETIC SHELL MORPHOLOGY
Authors: EFTAXIAS E. , VASILAKAKI M. , TROHIDOU K. N.
Published: August 2007

We have used the Monte Carlo simulation technique to investigate the mechanism that gives the exchange bias effects on composite magnetic nanoparticles with Ferromagnetic (FM) core/Antiferromagnetic (AFM) shell morphology. Our study shows that:.

(a) the exchange bias field depends mainly on the structure of the interface and less on its size,.

(b) when the shell size becomes bigger than the core size the exchange bias field decreases,.

(c) the size of the vertical shift depends on the total number of uncompensated spins in the nanoparticle and.

(d) the training effect has its origin to the rearrangement of the spins at the FM/AFM interface.

Our results are in good agreement with experimental findings.
The Evolution of Multicellularity: A Minor Major Transition?
Authors: Grosberg Richard K. , Strathmann Richard R.
Published: August 2007

Benefits of increased size and functional specialization of cells have repeatedly promoted the evolution of multicellular organisms from unicellular ancestors. Many requirements for multicellular organization (cell adhesion, cell-cell communication and coordination, programmed cell death) likely evolved in ancestral unicellular organisms. However, the evolution of multicellular organisms from unicellular ancestors may be opposed by genetic conflicts that arise when mutant cell lineages promote their own increase at the expense of the integrity of the multicellular organism. Numerous defenses limit such genetic conflicts, perhaps the most important being development from a unicell, which minimizes conflicts from selection among cell lineages, and redistributes genetic variation arising within multicellular individuals between individuals. With a unicellular bottleneck, defecting cell lineages rarely succeed beyond the life span of the multicellular individual. When multicellularity arises through aggregation of scattered cells or when multicellular organisms fuse to form genetic chimeras, there are more opportunities for propagation of defector cell lineages. Intraorganismal competition may partly explain why multicellular organisms that develop by aggregation generally exhibit less differentiation than organisms that develop clonally.
Complement Regulatory Genes and Hemolytic Uremic Syndromes
Authors: Kavanagh David , Richards Anna , Atkinson John
Published: August 2007

Hemolytic uremic syndrome is a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. It is one of a group of conditions termed the thrombotic microangiopathies, which are characterized by prominent endothelial cell injury. It may be diarrheal-associated or atypical (aHUS). Evidence for a pathogenic role of the alternative pathway of complement was first suggested in 1974. Mutations in the complement regulatory proteins factor H, membrane cofactor protein (CD46), and factor I predispose to aHUS development. Mutations of the activating components factor B and complement C3 have also been reported. Penetrance is ∼50%, suggesting other genetic and environmental modifiers are needed for disease expression. Identification of mutations is important owing to differences in mortality, renal survival, and outcome of renal transplantation. Current treatment is plasma infusion/exchange, but complement inhibitor therapy provides hope for the future.
Grounded Cognition
Authors: Barsalou Lawrence W.
Published: August 2007

Grounded cognition rejects traditional views that cognition is computation on amodal symbols in a modular system, independent of the brain's modal systems for perception, action, and introspection. Instead, grounded cognition proposes that modal simulations, bodily states, and situated action underlie cognition. Accumulating behavioral and neural evidence supporting this view is reviewed from research on perception, memory, knowledge, language, thought, social cognition, and development. Theories of grounded cognition are also reviewed, as are origins of the area and common misperceptions of it. Theoretical, empirical, and methodological issues are raised whose future treatment is likely to affect the growth and impact of grounded cognition.
Involvement of AMP-activated protein kinase in beneficial effects of betaine on high-sucrose diet-induced hepatic steatosis
Authors: Song Zhenyuan , Deaciuc Ion , Zhou Zhanxiang , Song Ming , Chen Theresa , Hill Daniell , McClain Craig J.
Published: August 2007

Although simple steatosis was originally thought to be a pathologically inert histological change, fat accumulation in the liver may play a critical role not only in disease initiation, but also in the progression to nonalcoholic steatohepatitis and cirrhosis. Therefore, prevention of fat accumulation in the liver may be an effective therapy for multiple stages of nonalcoholic fatty liver disease (NAFLD). Promising beneficial effects of betaine supplementation on human NAFLD have been reported in some pilot clinical studies; however, data related to betaine therapy in NAFLD are limited. In this study, we examined the effects of betaine on fat accumulation in the liver induced by high-sucrose diet and evaluated mechanisms by which betaine could attenuate or prevent hepatic steatosis in this model. Male C57BL/6 mice weighing 20 ± 0.5 g (means ± SE) were divided into four groups (8 mice per group) and started on one of four treatments: standard diet (SD), SD+betaine, high-sucrose diet (HS), and HS + betaine. Betaine was supplemented in the drinking water at a concentration of 1% (wt/vol) (anhydrous). Long-term feeding of high-sucrose diet to mice caused significant hepatic steatosis accompanied by markedly increased lipogenic activity. Betaine significantly attenuated hepatic steatosis in this animal model, and this change was associated with increased activation of hepatic AMP-activated protein kinase (AMPK) and attenuated lipogenic capability (enzyme activities and gene expression) in the liver. Our findings are the first to suggest that betaine might serve as a therapeutic tool to attenuate hepatic steatosis by targeting the hepatic AMPK system.
Do vasoregulatory mechanisms in exercising human muscle compensate for changes in arterial perfusion pressure?
Authors: Walker Kathryn L. , Saunders Natasha R. , Jensen Dennis , Kuk Jennifer L. , Wong Suzi-Lai , Pyke Kyra E. , Dwyer Erin M. , Tschakovsky Michael E.
Published: August 2007

We tested the hypothesis that vasoregulatory mechanisms completely counteract the effects of sudden changes in arterial perfusion pressure on exercising muscle blood flow. Twelve healthy young subjects (7 female, 5 male) lay supine and performed rhythmic isometric handgrip contractions (2 s contraction/ 2 s relaxation 30% maximal voluntary contraction). Forearm blood flow (FBF; echo and Doppler ultrasound), mean arterial blood pressure (arterial tonometry), and heart rate (ECG) were measured. Moving the arm between above the heart (AH) and below the heart (BH) level during contraction in steady-state exercise achieved sudden ∼30 mmHg changes in forearm arterial perfusion pressure (FAPP). We analyzed cardiac cycles during relaxation (FBFrelax). In an AH-to-BH transition, FBFrelax increased immediately, in excess of the increase in FAPP (∼69% vs. ∼41%). This was accounted for by pressure-related distension of forearm resistance vasculature [forearm vascular conductance (FVCrelax) increased by ∼19%]. FVCrelax was restored by the second relaxation. Continued slow decreases in FVCrelax stabilized by 2 min without restoring FBFrelax. In a BH-to-AH transition, FBFrelax decreased immediately, in excess of the decrease in FAPP (∼37% vs. ∼29%). FVCrelax decreased by ∼14%, suggesting pressure-related passive recoil of resistance vessels. The pattern of FVCrelax was similar to that in the AH-to-BH transition, and FBFrelax was not restored. These data support rapid myogenic regulation of vascular conductance in exercising human muscle but incomplete flow restoration via slower-acting mechanisms. Local arterial perfusion pressure is an important determinant of steady-state blood flow in the exercising human forearm.
Energy flux, more so than energy balance, protein intake, or fitness level, influences insulin-like growth factor-I system responses during 7 days of increased physical activity
Authors: Rarick Kevin R. , Pikosky Matthew A. , Grediagin Ann , Smith Tracey J. , Glickman Ellen L. , Alemany Joseph A. , Staab Jeffery S. , Young Andrew J. , Nindl Bradley C.
Published: August 2007

The purpose of this study was to determine the impact of dietary factors and exercise-associated factors on the response of IGF-I and its binding proteins (IGFBPs) during a period of increased physical activity. Twenty-nine men completed a 4-day ( days 1–4) baseline period of a controlled energy balanced diet while maintaining their normal physical activity level followed by 7 days ( days 5–11) of a 1,000 kcal/day increase in physical activity above their normal activity levels. Two subject groups, one sedentary (Sed, mean V̇o2peak: 39 ml·kg−1·min−1, n = 7) and one fit (FIT1, mean V̇o2peak: 56 ml·kg−1·min−1, n = 8) increased energy intake to maintain energy balance throughout the 7-day intervention. In two other fit subject groups (FIT2, n = 7 and FIT3, n = 7), energy intake remained at baseline resulting in a 1,000 kcal/day exercise-induced energy deficit. Of these, FIT2 received an adequate protein diet (0.9 g/kg), and FIT3 received a high-protein diet (1.8 g/kg). For all four groups, IGF-I, IGFBP-3, and the acid labile subunit (ALS) were significantly decreased by day 11 (27 ± 4%, 10 ± 2%, and 19 ± 4%, respectively) and IGFBP-2 significantly increased by 49 ± 21% following day 3. IGFBP-1 significantly increased only in the two negative energy balance groups, FIT2 (38 ± 6%) and FIT3 (46 ± 8%). Differences in initial fitness level and dietary protein intake did not alter the IGF-I system response to an acute increase in physical activity. Decreases in IGF-I were observed during a moderate increase in physical activity despite maintaining energy balance, suggesting that currently unexplained exercise-associated mechanisms, such as increased energy flux, regulate IGF-I independent of energy deficit.
Oscillatory pressure wave transmission from the upper airway to the carotid artery
Authors: Howitt Lauren , Kairaitis Kristina , Kirkness Jason P. , Garlick Sarah R. , Wheatley John R. , Byth Karen , Amis Terence C.
Published: August 2007

Snoring-associated vibration energy transmission from the upper airway to the carotid artery has been hypothesized as a potential atherosclerotic plaque initiating/rupturing event that may provide a pathogenic mechanism linking snoring and embolic stroke. We examined transmission of oscillatory pressure waves from the pharyngeal lumen to the common carotid artery wall and lumen in seven male, anesthetized, spontaneously breathing New Zealand White rabbits. Airflow was monitored via a pneumotachograph inserted in series in the intact trachea. Fifteen 20-s runs of, separately, 40-, 60-, and 90-Hz oscillatory pressure waves [pressure amplitude in the trachea (Ptramp), amplitude 2–20 cmH2O] were generated by a loudspeaker driven by a sine wave generator and amplifier and superimposed on tidal breathing via the cranial tracheal connector. Pressure transducer-tipped catheters measured pressure amplitudes in the tissues adjacent to the common carotid artery bifurcation (Pctiamp) and within the lumen (carotid sinus; Pcsamp). Data were analyzed using power spectrum analysis and linear mixed-effects statistical modeling. Both the frequency (f) and amplitude of the injected pressure wave influenced Pctiampand Pcsamp, in that ln Pctiamp= 1.2(Ptramp) + 0.02(f) − 5.2, and ln Pcsamp= 0.6(Ptramp) + 0.02(f) − 4.9 (both P < 0.05). Across all frequencies tested, transfer of oscillatory pressure across the carotid artery wall was associated with an amplitude gain, as expressed by a Pcsamp-to-Pctiampratio of 1.8 ± 0.3 ( n = 6). Our findings confirm transmission of oscillatory pressure waves from the upper airway lumen to the peripharyngeal tissues and across the carotid artery wall to the lumen. Further studies are required to establish the role of this incident energy in the pathogenesis of carotid artery vascular disease.
For the Safety and Benefit of Current and Future Patients
Authors: Hansson Mats G.
Published: August 2007

Pathology biobanks are vital assets for medical care and treatment of current and future patients. In association with good clinical data they are also useful for biomedical research regarding the underlying mechanisms of human disease. Recent regulations have suggested the obtainment of a specific and explicit informed consent as a prerequisite for using human tissue samples with these ends in mind. However, the choice and strict use of informed consent for balancing conflicting interests associated with biobank-related research can in practice be detrimental to patient safety with regard to diagnosis, medical care and treatment. In this article I argue that a ‘safety principle’ should have priority and suggest how this could be implemented in clinical practice and in association with biomedical research.
Tissue Banking in a Regulated Environment – Does This Help the Patient?
Authors: Clark Brian J.
Published: August 2007

The difficulties with ‘retained organs’ in the UK have resulted in a new legislation relating to human organs, tissues, and bodies – the Human Tissue Act 2004 and the Human Tissue Act Scotland 2006 are now in place. The new laws apply to a wide range of activities including transplantation, education, clinical audit, the practice of autopsies, anatomical examination and others, including the use of human tissues in research. Pathobiology research that uses human tissues is now undertaken in a regulated environment in the UK. The details of these regulations are described and the consequences discussed. In the second part of the paper the patient’s views and expectations in this new setting are forwarded.
The Genome Austria Tissue Bank (GATiB)
Authors: Asslaber M. , Abuja P.M. , Stark K. , Eder J. , Gottweis H. , Trauner M. , Samonigg H. , Mischinger H.J. , Schippinger W. , Berghold A. , Denk H. , Zatloukal K.
Published: August 2007

In the context of the Austrian Genome Program, a tissue bank is being established (Genome Austria Tissue Bank, GATiB) which is based on a collection of diseased and corresponding normal tissues representing a great variety of diseases at their natural frequency of occurrence from a non-selected Central European population of more than 700,000 patients. Major emphasis is put on annotation of archival tissue with comprehensive clinical data, including follow-up data. A specific IT infrastructure supports sample annotation, tracking of sample usage as well as sample and data storage. Innovative data protection tools were developed which prevent sample donor re-identification, particularly if detailed medical and genetic data are combined. For quality control of old archival tissues, new techniques were established to check RNA quality and antigen stability. Since 2003, GATiB has changed from a population-based tissue bank to a disease-focused biobank comprising major cancers such as colon, breast, liver, as well as metabolic liver diseases and organs affected by the metabolic syndrome. Prospectively collected tissues are associated with blood samples and detailed data on the sample donor’s disease, lifestyle and environmental exposure, following standard operating procedures. Major emphasis is also placed on ethical, legal and social issues (ELSI) related to biobanks. A specific research project and an international advisory board ensure the proper embedding of GATiB in society and facilitate international networking.
Legal Aspects of Tissue Banking
Authors: Gassner Ulrich M.
Published: August 2007

There exists no clear national or international consensus in key issues of tissue banking. This holds especially true for the fundamental concept of informed consent. During recent years, the harmonization of norms needed for international collaboration has made crucial progress solely in Europe, namely through legal framing. The norms relating to tissue banking are, however, under permanent construction not only in Europe but throughout the world. Consequently, anybody involved in tissue banking is well advised to observe the evolution of the legal and regulatory environment in the particular jurisdiction.
Principles of Pediatric Pain Management during the End-of-Life Period
Authors: Friedrichsdorf Stefan J. , Collins John J.
Published: August 2007

More than 80% of children with a life-limiting condition such as cancer or a neurodegenerative disease suffer from pain during their last week of life. This article reviews the principles of pediatric pain management and addresses characteristics and pitfalls of integrative and pharmacological therapies during the end-of-life period of a child.Providing a good pain management for a dying child is one of the many domains of pediatric palliative care and usually requires a holistic, multidisciplinary approach and the knowledge to apply appropriate analgesic drugs in combination with integrative nondrug therapies.
Expression of Pain by Children and Its Assessment in Kuwait
Authors: Alwugyan Dhari , Alroumi Faisal , Zureiqi Mohammad
Published: August 2007

Objective: To study the ability of children to describe, localize, and assess the intensity of their current pain and to compare their evaluation with those of their parents. Subjects and Methods: A cross-sectional survey was conducted among 281 native Arabic-speaking children, 6–12 years old, presenting with acute pain to the emergency room accompanied by at least one adult. Data were collected in Al-Amiri, Mubarak Al-Kabeer, Al-Adan, Al-Farwaniya and Al-Jahra hospitals by interviewing children and by giving a self-administered questionnaire to the accompanying adult. Intensity of pain was measured using the Faces Pain Scale. Children described their pain using 23 verbal expressions. Results: The most frequently used words to describepain were ‘it hurts’ and ‘it hurts a lot’ followed by a ‘burning sensation’.The most common sites of pain were the abdomen, pelvis, and loin. Intensity of pain was associated with birth order and higher number of siblings, lower number of previous pain episodes, lower family income, and lower educational level of the mother. No relationship was found between self-reported pain intensity and nationality, area of residence, gender, orfather’s educational level. There was no agreement in pain intensity assessment between parents and children. Conclusion: The study shows that children were able to verbalize their current pain, its intensity and site. The Faces Pain Scale was easy to administer and useful in measuring the intensity of pain.
Managing Palliative Care at Home
Authors: Hannan Julia
Published: August 2007

This paper outlines the principles of palliative care (PC) provision for sick children at home, in the UK. The differences between home and hospital with regard to the illness and availability and type of services and equipment are discussed. The need to plan for the availability of appropriate professional staff, equipment, medication, information and the procedure when the child dies is discussed. Successful PC at home is possible for most children, if plans are made for all potential eventualities. These principles of PC may be helpful in delivering PC at home in other countries.
Armfuls of Time: The Psychological Experience of the Child with a Life-Threatening Illness
Authors: Sourkes Barbara M.
Published: August 2007

The seriously ill or dying child, his/her parents, and siblings all face daunting challenges. The services of a multidisciplinary team are required for optimal care. Experts in the fields of child psychology, psychiatry, and/or pediatric palliative care should be included in this team. Different aspects of the care take into consideration the role of the child in the family, the impact of the diagnosis on the child, loss of control and the threat of these losses. These have to be addressed to ensure an optimal psychological outcome for all concerned, irrespective of the eventual survival or demise of the sick child.
Polymerase-Chain-Reaction-Based Detection of Fetal Rhesus D and Y-Chromosome-Specific DNA in the Whole Blood of Pregnant Women during Different Trimesters of Pregnancy
Authors: Al-Yatama M.K. , Mustafa A.S. , Al-Kandari F.M. , Khaja N. , Zohra K. , Monem R.A. , Abraham S.
Published: August 2007

Objective: The aim of this study was to determine whether or not a noninvasive procedure utilizing maternal peripheral blood as the source of DNA and polymerase chain reaction (PCR) could be used to detect fetal rhesus D (RhD) status as well as fetal gender during different gestational stages of pregnancy. Materials and Methods: Maternal blood samples were obtained from 54 RhD-negative pregnant women during the first trimester (6–13 weeks, n = 14), second trimester (14–26 weeks, n = 26) and third trimester (27–40 weeks, n = 14). Genomic DNA was extracted from the whole blood and analyzed by seminested and nested PCR for detection of DNA sequences corresponding to RhD (n = 54) and Y chromosome (n = 48) using RhD and Y-chromosome-specific oligonucleotide primers, respectively. The seminested/nested PCR results were compared with the RhD status and gender of the babies after delivery. Results: The sensitivity and specificity of seminested PCR for detection of fetal RhD positivity in whole blood of pregnant women were 81 and 100%, respectively, while the sensitivity and specificity of nested PCR for detection of male fetuses, using Y-chromosome-specific DNA as a marker, were 96 and 91%, respectively. There were no significant differences in the PCR results with samples obtained from women at different gestational stages of pregnancy. Conclusion: Seminested and nested PCRs for detection of fetal RhD and gender status, respectively, by using the blood of pregnant women during different gestational stages of pregnancy, are reliable noninvasive procedures with high sensitivity and specificity.