bluuebunny/crossref_metadata_2025 huggingface dataset:
Levels of abstraction in students' understanding of the concept of algorithm
Authors: Perrenet Jacob , Kaasenbrood Eric
Published: July 2006

In a former, mainly quantitative, study we defined four levels of abstraction in Computer Science students' thinking about the concept of algorithm. We constructed a list of questions about algorithms to measure the answering level as an indication for the thinking level. The answering level generally increased between successive year groups of Bachelor students as well as within year groups during the year, mainly from the second to the third level. The reliability of the instrument appeared to be good, but the validity remained unclear. In this current study, more qualitative methods are used to investigate the validity; the results indicate that the validity is good too. The study uses a theoretical perspective from Mathematics Education research and points at the fruitfulness of combining quantitative methods with qualitative methods.
The first programming course
Authors: Bergin Joe , Lister Raymond , Owens Barbara Boucher , McNally Myles
Published: July 2006

This panel will discuss ways to engage undergraduates in computing and then to keep them as majors. A special emphasis will be on attracting females to computing. The panelists will discuss the relative strengths and weaknesses of four environments especially designed for the teaching of the first programming course.
Educating computing professionals at postgraduate level
Authors: Joyce Donald
Published: July 2006

In this poster, we review experience gained and lessons learned in offering two postgraduate programmes (Master of Computing and Doctor of Computing) aimed at educating computing professionals. Aspects addressed include structure of the programmes, the use of group assessment items, development of students' analysis and communication skills, and assessment of doctoral coursework.
Animation programming
Authors: Moses Louise
Published: July 2006

The current problem faced by many computing departments is that only those already self-selected into computing sign up for "CS121 Programming and Problem Solving I", or the similarly named and presented first course. An Animation Programming course using ActionScript 2.0 (as found in Flash MX 2004 or Flash 8) will provide a high quality object oriented language and will have enormous student appeal.
Systems thinking as a basis for ambient intelligence
Authors: Bureš Vladimír
Published: July 2006

Recently, ambient intelligence as a vision of information society of the future has become the challenge for many theorists and practitioners. Fulfilment of this vision should begin, among others, with adjustment of contemporary ways of education of future managers, who will be a significant part of such society. Since computer science and related disciplines have originated in systems movement, systems thinking seems to be a good starting point that already brings satisfying results.
HIV protease inhibitors activate the unfolded protein response and disrupt lipid metabolism in primary hepatocytes
Authors: Zhou Huiping , Gurley Emily C. , Jarujaron Sirikalaya , Ding Hong , Fang Youwen , Xu Zhumei , Pandak William M. , Hylemon Phillip B.
Published: July 2006

Treatment of human immunodeficiency virus (HIV)-infected patients with HIV protease inhibitors (PIs) has been associated with serious lipid disturbances. However, the incidence and degree of impaired lipid metabolism observed in the clinic vary considerably between individual HIV PIs. Our previous studies demonstrated that HIV PIs differ in their ability to increase the levels of transcriptionally active sterol regulatory element-binding proteins (SREBPs), activate the unfolded protein response (UPR), induce apoptosis, and promote foam cell formation in macrophages. In the present study, we examined the effects of three HIV PIs, including amprenavir, atazanavir, and ritonavir, on the UPR activation and the expression of key genes involved in lipid metabolism in primary rodent hepatocytes. Both atazanavir and ritonavir activated the UPR, induced apoptosis, and increased nuclear SREBP levels, but amprenavir had no significant effect at the same concentrations. In rat primary hepatocytes, cholesterol 7α-hydroxylase (CYP7A1) mRNA levels were significantly decreased by atazanavir (38%) and ritonavir (56%) but increased by amprenavir (90%); 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase mRNA levels were increased by amprenavir (23%) but not by ritonavir and atazanavir; low-density lipoprotein receptor mRNA was increased by atazanavir (20%) but not by amprenavir and ritonavir. Similar results were obtained in mouse primary hepatocytes. Atazanavir and ritonavir also decreased CYP7A1 protein levels and bile acid biosynthesis, while amprenavir had no significant effect. The current results may help provide a better understanding of the cellular mechanisms of HIV PI-induced dyslipidemia and also provide useful information to help predict clinical adverse effects in the development of new HIV PIs.
Beating myocardium counteracts myogenic tone of coronary microvessels: involvement of ATP-sensitive potassium channels
Authors: Takeda Satoru , Komaru Tatsuya , Takahashi Katsuaki , Sato Kouichi , Kanatsuka Hiroshi , Kokusho Yasunori , Shirato Kunio , Shimokawa Hiroaki
Published: July 2006

Myogenic tone is intrinsic to vascular tissue and plays an important role in determining basal coronary resistance. However, the effect of the beating heart on myogenic tone is unknown. We investigated the effects of myocardium-derived vasoactive factors on the myogenic tone of coronary microvessels in the resting condition and during increased metabolism. Pressurized isolated coronary vessels (detector vessel, DV) of rabbits ( n = 33, maximal inner diameter 201 ± 8 μm) were gently placed on beating hearts of anesthetized dogs and observed with an intravital microscope equipped with a floating objective. To shut off the myocardium-derived vasoactive signals, we placed plastic film between DV and the heart. The intravascular pressure was changed from 120 to 60 cmH2O, and pressure-diameter curves were obtained with and without the contact of DV and the myocardium. The direct contact shifted the pressure-diameter curve upward ( P < 0.05 vs. without contact), and myogenic tone was reduced by ∼40%. When endothelium of DV was denuded, the shift persisted, but the degree of shift was reduced to 10% ( P < 0.05 vs. with endothelium). The shift was abolished by glibenclamide, an ATP-sensitive potassium (KATP) channel blocker. A similar upward shift was induced by rapid pacing, but the shift was not blocked by glibenclamide. We conclude that the beating myocardium counteracts myogenic tone by releasing transferable vasoactive signals that affect the endothelium and the vascular smooth muscle, and that the signals are solely mediated by the activation of KATP channels, unlike the rapid pacing-induced vasoactive factors.
Age and flow-mediated dilation: a comparison of dilatory responsiveness in the brachial and popliteal arteries
Authors: Parker Beth A. , Ridout Samuel J. , Proctor David N.
Published: July 2006

Previous investigations of age-associated changes in flow-mediated vasodilation (FMD) in women have been limited to the upper extremity and have not accounted for possible age differences in the stimulus for dilation. The purpose of the present study was to compare age differences in brachial and popliteal FMD and its stimulus (changes in shear rate following occlusion). Ultrasound-derived diameters and Doppler flow velocities of the brachial and popliteal arteries were measured in 14 young (20- to 30-yr-old) and 14 older (60- to 79-yr-old) healthy women at rest and during and after 5 min of distal cuff occlusion. Resting diameters were similar (both P > 0.39) in both age groups. Peak shear rate did not differ with age in either artery: ∼1,300–1,400 and ∼400–500 s−1in brachial and popliteal arteries, respectively. FMD (percent change above diameter measured during occlusion) was ∼50–60% lower ( P < 0.05) in the brachial (15.8 + 0.8% vs. 8.1 + 1.5%) and popliteal (4.6 ± 0.7% vs. 1.8 ± 0.4%) arteries of the older women. The normalized response of the brachial and popliteal arteries (%FMD per unit change in shear rate) was also reduced with age (55% and 53%, respectively) but did not exhibit limb specificity. Additionally, endothelium-independent dilation, as assessed by administration of nitroglycerin, was similarly blunted (by 45–65%) in brachial and popliteal arteries of older women. These results suggest that 1) brachial and popliteal artery FMD (after 5 min of distal occlusion) are similarly reduced with age, 2) when normalized to the change in shear stimulus, both arteries are equally responsive to 5 min of distal cuff occlusion in women, and 3) the age-associated decline in FMD may be attributable in part to diminished smooth muscle responsiveness.
Development of the ovine fetal cardiovascular defense to hypoxemia towards full term
Authors: Fletcher Andrew J. W. , Gardner David S. , Edwards C. Mark B. , Fowden Abigail L. , Giussani Dino A.
Published: July 2006

We tested the hypothesis that fetal cardiovascular responses to hypoxemia change close to full term in relation to the prepartum increase in fetal basal cortisol and investigated, in vivo, the neural and endocrine mechanisms underlying these changes. Fetal heart rate and peripheral hemodynamic responses to 1 h of hypoxemia were studied in 25 chronically instrumented sheep within three narrow gestational age ranges: 125–130 ( n = 13), 135–140 ( n = 6), and >140 ( n = 6) days (full term ∼145 days). Chemoreflex function and plasma concentrations of vasoconstrictor hormones were measured. Reductions in fetal arterial Po2 during hypoxemia were similar at all ages. At 125–130 days, hypoxemia elicited transient bradycardia, femoral vasoconstriction, and increases in plasma concentrations of catecholamines, neuropeptide Y (NPY), AVP, ACTH, and cortisol. Close to full term, in association with the prepartum increase in fetal basal cortisol, there was a developmental increase in the magnitude and persistence of fetal bradycardia and in the magnitude of the femoral constrictor response to hypoxemia. The mechanisms mediating these changes close to full term included increases in the gain of chemoreflex function and in the magnitudes of the fetal NPY and AVP responses to hypoxemia. Data combined irrespective of gestational age revealed significant correlations between fetal basal cortisol and fetal bradycardia, femoral resistance, chemoreflex function, and plasma AVP concentrations. The data show that the fetal cardiovascular defense to hypoxemia changes in pattern and magnitude just before full term because of alterations in the gain of the neural and endocrine mechanisms mediating them, in parallel with the prepartum increase in fetal basal cortisol.
Modification of intracellular calcium concentration in cardiomyocytes by inhibition of sarcolemmal Na+/H+exchanger
Authors: Saini Harjot K. , Dhalla Naranjan S.
Published: July 2006

Although the Na+/H+exchanger (NHE) is considered to be involved in regulation of intracellular Ca2+concentration ([Ca2+]i) through the Na+/Ca2+exchanger, the exact mechanisms of its participation in Ca2+handling by cardiomyocytes are not fully understood. Isolated rat cardiomyocytes were treated with or without agents that are known to modify Ca2+movements in cardiomyocytes and exposed to an NHE inhibitor, 5-( N-methyl- N-isobutyl)amiloride (MIA). [Ca2+]iin cardiomyocytes was measured spectrofluorometrically with fura 2-AM in the absence or presence of KCl, a depolarizing agent. MIA increased basal [Ca2+]iand augmented the KCl-induced increase in [Ca2+]iin a concentration-dependent manner. The MIA-induced increase in basal [Ca2+]iwas unaffected by extracellular Ca2+, antagonists of the sarcolemmal (SL) L-type Ca2+channel, and inhibitors of the SL Na+/Ca2+exchanger, SL Ca2+pump ATPase and mitochondrial Ca2+uptake. However, the MIA-induced increase in basal [Ca2+]iwas attenuated by inhibitors of SL Na+-K+-ATPase and sarcoplasmic reticulum (SR) Ca2+transport. On the other hand, the MIA-mediated augmentation of the KCl response was dependent on extracellular Ca2+concentration and attenuated by agents that inhibit SL L-type Ca2+channels, the SL Na+/Ca2+exchanger, SL Na+-K+-ATPase, and SR Ca2+release channels and the SR Ca2+pump. However, the effect of MIA on the KCl-induced increase in [Ca2+]iremained unaffected by treatment with inhibitors of SL Ca2+pump ATPase and mitochondrial Ca2+uptake. MIA and a decrease in extracellular pH lowered intracellular pH and increased basal [Ca2+]i, whereas a decrease in extracellular pH, in contrast to MIA, depressed the KCl-induced increase in [Ca2+]iin cardiomyocytes. These results suggest that NHE may be involved in regulation of [Ca2+]iand that MIA-induced increases in basal [Ca2+]i, as well as augmentation of the KCl-induced increase in [Ca2+]i, in cardiomyocytes are regulated differentially.
Ouabain decreases sarco(endo)plasmic reticulum calcium ATPase activity in rat hearts by a process involving protein oxidation
Authors: Kennedy David J. , Vetteth Sandeep , Xie Miaorong , Periyasamy Sankaridrug M. , Xie Zijian , Han Chi , Basrur Venkatesha , Mutgi Krishna , Fedorov Vladimir , Malhotra Deepak , Shapiro Joseph I.
Published: July 2006

The effect of cardiac glycosides to increase cardiac inotropy by altering Ca2+cycling is well known but still poorly understood. The studies described in this report focus on defining the effects of ouabain signaling on sarcoplasmic reticulum Ca2+-ATPase function. Rat cardiac myocytes treated with 50 μM ouabain demonstrated substantial increases in systolic and diastolic Ca2+concentrations. The recovery time constant for the Ca2+transient, τ[Formula: see text], was significantly prolonged by ouabain. Exposure to 10 μM H2O2, which causes an increase in intracellular reactive oxygen species similar to that of 50 μM ouabain, caused a similar increase in τ[Formula: see text]. Concurrent exposure to 10 mM N-acetylcysteine or an aqueous extract from green tea (50 mg/ml) both prevented the increases in τ[Formula: see text] as well as the changes in systolic or diastolic Ca2+concentrations. We also observed that 50 μM ouabain induced increases in developed pressure in addition to diastolic dysfunction in the isolated perfused rat heart. Coadministration of ouabain with N-acetylcysteine prevented these increases. Analysis of sarcoplasmic reticulum Ca2+-ATPase protein revealed increases in both the oxidation and nitrotyrosine content in the ouabain-treated hearts. Liquid chromatography-mass spectrometric analysis confirmed that the sarcoplasmic reticulum Ca2+-ATPase protein from ouabain-treated hearts had modifications consistent with oxidative and nitrosative stress. These data suggest that ouabain induces oxidative changes of the sarcoplasmic reticulum Ca2+-ATPase structure and function that may, in turn, produce some of the associated changes in Ca2+cycling and physiological function.
Mechanisms leading to reversible mechanical dysfunction in severe CAD: alternatives to myocardial stunning
Authors: Mazzadi Alejandro N. , André-Fouët Xavier , Costes Nicolas , Croisille Pierre , Revel Didier , Janier Marc F.
Published: July 2006

Patients with severe chronic coronary artery disease (CAD) exhibit a highly altered myocardial pattern of perfusion, metabolism, and mechanical performance. In this context, the diagnosis of stunning remains elusive not only because of methodological and logistic considerations, but also because of the pathophysiological characteristics of the myocardium of these patients. In addition, a number of alternative pathophysiological mechanisms may act by mimicking the functional manifestations usually attributed to stunning. The present review describes three mechanisms that could theoretically lead to reversible mechanical dysfunction in these patients: myocardial wall stress, the tethering effect, and myocardial expression and release of auto- and paracrine agents. Attention is focused on the role of these mechanisms in scintigraphically “normal” regions (i.e., regions usually showing normal perfusion, glucose metabolism, and cellular integrity as assessed by nuclear imaging techniques), in which stunning is usually considered, but these mechanisms could also operate throughout the viable myocardium. We hypothesize that reversion of these three mechanisms could partially explain the unexpected functional benefit after reperfusion recently highlighted by high-spatial-resolution imaging techniques.
Functional and genomic changes induced by alveolar transmigration in human neutrophils
Authors: Coldren Christopher D. , Nick Jerry A. , Poch Katie R. , Woolum Malcolm D. , Fouty Brian W. , O’Brien James M. , Gruber Michael P. , Zamora Martin R. , Svetkauskaite Daiva , Richter Don A. , He Qianbin , Park Jong Sung , Overdier Katherine H. , Abraham Edward , Geraci Mark W.
Published: July 2006

Although the accumulation of neutrophils in the lungs and airways is common to many inflammatory lung diseases, including acute lung injury, the alterations that neutrophils undergo as they leave the peripheral circulation and migrate into the lungs have not been well characterized. Human volunteers were exposed to endotoxin by bronchoscopic instillation. The resulting air space neutrophil accumulation and peripheral blood neutrophils were isolated 16 h later, compared with circulating neutrophils isolated before or after to the pulmonary endotoxin exposure, and compared with circulating neutrophils exposed to endotoxin in vitro. Microarray analysis was performed on air space, circulatory, and in vitro endotoxin-stimulated neutrophils. Functional analysis included the determination of neutrophil apoptosis, chemotaxis, release of cytokines and growth factors, and superoxide anion release. Dramatic gene expression differences were apparent between air space and circulating neutrophils: ∼15% of expressed genes have altered expression levels, including broad increases in inflammatory- and chemotaxis-related genes, as well as antiapoptotic and IKK-activating pathways. Functional analysis of air space compared with circulating neutrophils showed increased superoxide release, diminished apoptosis, decreased IL-8-induced chemotaxis, and a pattern of IL-8, macrophage inflammatory protein-1β, monocyte chemoattractant protein-1, and tumor necrosis factor-α release different from either unstimulated or LPS-stimulated circulating neutrophils. Many of these changes are not elicited by in vitro treatment with endotoxin. Limited differences were detected between circulating neutrophils isolated before and 16 h after pulmonary endotoxin instillation. These results suggest that neutrophils sequestered in the lung become fundamentally different from those resident in the circulation, and this difference is distinct from in vitro activation with endotoxin.
Voltage-gated K+channels at an early stage of chronic hypoxia-induced pulmonary hypertension in newborn piglets
Authors: Fike Candice D. , Kaplowitz Mark R. , Zhang Yongmei , Madden Jane A.
Published: July 2006

Our purpose was to determine whether smooth muscle cell membrane properties are altered in small pulmonary arteries (SPA) of piglets at an early stage of pulmonary hypertension. Piglets were raised in either room air (control) or hypoxia for 3 days. A microelectrode technique was used to measure smooth muscle cell membrane potential ( Em) in cannulated, pressurized SPA (100- to 300-μm diameter). SPA responses to the voltage-gated K+(KV) channel antagonist 4-aminopyridine (4-AP) and the KV1 family channel antagonist correolide were measured. Other SPA were used to assess amounts of KV1.2, KV1.5, and KV2.1 (immunoblot technique). Emwas more positive in SPA of chronically hypoxic piglets than in SPA of comparable-age control piglets. The magnitude of constriction elicited by either 4-AP or correolide was diminished in SPA from hypoxic piglets. Abundances of KV1.2 were reduced, whereas abundances of both KV1.5 and KV2.1 were unaltered, in SPA from hypoxic piglets. At least partly because of reduced amounts of KV1.2, smooth muscle cell membrane properties are altered such that Emis depolarized and KVchannel family function is impaired in SPA of piglets at an early stage of chronic hypoxia-induced pulmonary hypertension.
Proteasome Inhibitor Drugs on the Rise
Authors: Joazeiro Claudio A.P. , Anderson Kenneth C. , Hunter Tony
Published: July 2006

In May 2003, the U.S. Food and Drug Administration granted the proteasome inhibitor bortezomib (Velcade) fast-track status for the treatment of multiple myeloma. This landmark represented the first approval of a drug targeting the ubiquitin-proteasome system (UPS) for any indication. More recently, at the AACR Special Conference “Ubiquitin and Cancer: From Molecular Targets and Mechanisms to the Clinic” (Orlando, FL, January 18-22, 2006), it became evident that drug discovery in the UPS is experiencing another round of great excitement. The reason—new clinical applications found for bortezomib, along with the promised success of new types of proteasome inhibitors reaching the clinic. (Cancer Res 2006; 66(16): 7840-2)
Hyponatremia after Transsphenoidal Surgery for Hypothalamo-Pituitary Tumors
Authors: Sata Akira , Hizuka Naomi , Kawamata Takakazu , Hori Tomokatsu , Takano Kazue
Published: July 2006

Transient diabetes insipidus is a well-known complication after transsphenoidal surgery (TSS). On the other hand, transient hyponatremia has been reported as being a delayed complication of TSS. Transient hyponatremia has been attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), but the details of hyponatremia have not been clarified. In the present study, we retrospectively reviewed 110 consecutive patients (39 males and 71 females, age 9–80 years) operated on transsphenoidally for pituitary and hypothalamic tumors. We investigated the frequency, time of onset, duration of hyponatremia after TSS, and analyzed possible factors associated with it. A postoperative sodium concentration <135 mEq/l was observed in 29 (26%) patients. Five patients were excluded from this study because their hyponatremia could be due to either overdose of desmopressin or SIADH for meningitis. Therefore, we investigated 24 (22%) patients with hyponatremia in this study. The sodium levels in the patients with hyponatremia ranged from 110 to 134, with a mean of 126.2 ± 5.3 mEq/l. Hyponatremia was observed on average on postoperative day 9.5 ± 2.4, the serum sodium levels normalized within 3.8 ± 1.7 days. Hyponatremia occurred in patients with non-functioning pituitary adenoma (26%, 11/42), Rathke’s cleft cyst (29%, 5/17), prolactinoma (31%, 4/13) and acromegaly (15%, 4/27). 18 patients (75%, 6/24) who developed hyponatremia had macrotumor (>10 mm), and 6 patients (25%, 6/24) had microtumor. The plasma arginine vasopressin (AVP) levels in the patients with hyponatremia ranged from 0.21 to 2.1, with a mean of 0.79 ± 0.46 pg/ml, and the levels were inversely correlated with plasma osmolality (r = –0.80, p = 0.002). The urine to plasma osmolality ratios were >1. All the patients received appropriate hormonal replacement, including hydrocortisone. These data showed that postoperative hyponatremia after TSS was not rare, and the hyponatremia was mainly associated with SIADH. As the hyponatremia could be a life-threatening complication, all patients should be screened for serum electrolytes after TSS.
Distributed Coordination of Simulated Robots Based on Self-Organization
Authors: Baldassarre Gianluca , Parisi Domenico , Nolfi Stefano
Published: July 2006

Distributed coordination of groups of individuals accomplishing a common task without leaders, with little communication, and on the basis of self-organizing principles, is an important research issue within the study of collective behavior of animals, humans, and robots. The article shows how distributed coordination allows a group of evolved, physically linked simulated robots (inspired by a robot under construction) to display a variety of highly coordinated basic behaviors such as collective motion, collective obstacle avoidance, and collective approach to light, and to integrate them in a coherent fashion. In this way the group is capable of searching and approaching a lighted target in an environment scattered with obstacles, furrows, and holes, where robots acting individually fail. The article shows how the emerged coordination of the group relies upon robust self-organizing principles (e.g., positive feedback) based on a novel sensor that allows the single robots to perceive the group's “average” motion direction. The article also presents a robust solution to a difficult coordination problem, which might also be encountered by some organisms, caused by the fact that the robots have to be capable of moving in any direction while being physically connected. Finally, the article shows how the evolved distributed coordination mechanisms scale very well with respect to the number of robots, the way in which robots are assembled, the structure of the environment, and several other aspects.
Self-Replication and Self-Assembly for Manufacturing
Authors: Ewaschuk Robert , Turney Peter D.
Published: July 2006

It has been argued that a central objective of nanotechnology is to make products inexpensively, and that self-replication is an effective approach to very low-cost manufacturing. The research presented here is intended to be a step towards this vision. We describe a computational simulation of nanoscale machines floating in a virtual liquid. The machines can bond together to form strands (chains) that self-replicate and self-assemble into user-specified meshes. There are four types of machines, and the sequence of machine types in a strand determines the shape of the mesh they will build. A strand may be in an unfolded state, in which the bonds are straight, or in a folded state, in which the bond angles depend on the types of machines. By choosing the sequence of machine types in a strand, the user can specify a variety of polygonal shapes. A simulation typically begins with an initial unfolded seed strand in a soup of unbonded machines. The seed strand replicates by bonding with free machines in the soup. The child strands fold into the encoded polygonal shape, and then the polygons drift together and bond to form a mesh. We demonstrate that a variety of polygonal meshes can be manufactured in the simulation, by simply changing the sequence of machine types in the seed.
Validation of Geriatric Depression Scale–5 Scores Among Sedentary Older Adults
Authors: Marquez David X. , McAuley Edward , Motl Robert W. , Elavsky Steriani , Konopack James F. , Jerome Gerald J. , Kramer Arthur F.
Published: July 2006

This study examined the validity of Geriatric Depression Scale–5 (GDS-5) scores among older sedentary adults based on its structural properties and relationship with external criteria. Participants from two samples ( Ns = 185 and 93; M ages = 66 and 67 years) completed baseline assessments as part of randomized controlled exercise trials. Confirmatory factor analysis supported a single-factor model for the GDS-5, the GDS-5 exhibited adequate sensitivity and specificity for screening depression, and scores from the 30 and 5 item GDS were strongly related. GDS-5 scores were strongly related with happiness and morale and moderatelyrelatedwithsatisfactionwithlife,loneliness,optimism,pessimism,perceived stress, negative health symptoms, and self-esteem. As expected, GDS-5 scores were weakly related with self-efficacy, cardiorespiratory fitness, and functional fitness. Support is provided for the validity of GDS-5 scores as a measure of depression among older sedentary adults participating in exercise studies.
The Comparability of the Standardized Mean Difference Effect Size Across Different Measures of the Same Construct
Authors: Nugent William R.
Published: July 2006

One of the most important effect sizes used in meta-analysis is the standardized mean difference (SMD). In this article, the conditions under which SMD effect sizes based on different measures of the same construct are directly comparable are investigated. The results show that SMD effect sizes from different measures of the same construct are directly comparable if and only if (Condition 1) there is a linear relationship between the true scores, and (Condition 2) there is a special linear relationship between the magnitude of the error variances of the involved measures. If only Condition 1 is met, then the reliability-corrected SMD effect sizes from the different measures are directly comparable. However, if Condition 1 is not met, then there will be nonlinear relationships between the true score metrics of two or more of the measures and systematic variability between SMD effect sizes that reflects these nonlinear relationships.
A Reliability Generalization Study on the Survey of Perceived Organizational Support
Authors: Hellman Chan M. , Fuqua Dale R. , Worley Jody
Published: July 2006

The Survey of Perceived Organizational Support (SPOS) is a unidimensional measure of the general belief held by an employee that the organization is committed to him or her, values his or her continued membership, and is generally concerned about the employee's well-being. In the interest of efficiency, researchers are often compelled to use a minimum number of SPOS items in their studies. This study reports on a reliability generalization across 62 published studies using the SPOS. Findings suggest that number of SPOS items and mean age of the sample are statistically significant in the relationship to reliability estimates. Additionally, mean age accounted for significant variance in internal consistency estimates over and above the number of items used.
United States, Globalization and the International System
Authors: Gaan Narottam
Published: July 2006

The belief that globalization has resulted in a multipolar global village transcending political, territorial, economic and socio-cultural particularities seems to be mistaken. On the contrary, it has been a convenient metaphor for the US to promote its own political and economic thinking on all nations at the expense of their cultural, social, economic and political diversity through the instrument of Transnational Corporations (TNCs) and the process of homogenization of production, labour and trade. The developing countries have remained captive to the wishes of these US-based corporations.

Globalization has not meant more democratization, freedom, independence or emergence of a multipolar world and regional powers. Instead, it has become an expedient euphemism for the US to decide the economy of the entire globe by its own domestic imperatives of providing a luxurious life style to its own citizens. The disintegration of Soviet Union and the end of Cold War, instead of ushering in a new world order, has resulted in the emergence of the US as a great leviathan, which by virtue of its own military prowess feels free to spread auits own liberal market economy binding all the nations of the world to all its nuances at the cost of their independence and sovereignty. American foreign policy behaviour with respect to Afghanistan, Iraq and global climate change negotiations is a testimony to this fact.
Biomechanical Comparison of Traditional and Locked Suture Configurations for Arthroscopic Repairs of the Rotator Cuff
Authors: Koganti Anil K. , Adamson Gregory J. , Gregersen Colin S. , Pink Marilyn M. , Shankwiler James A.
Published: July 2006

Background

The optimal suture configuration for arthroscopic rotator cuff repairs is controversial. “Locked” suture configurations, which use a combination of simple and transverse suture loops, have demonstrated better fixation strength than have traditional simple and horizontal mattress techniques.

Purpose

To compare traditional arthroscopic suture configurations to locked arthroscopic configurations in ability to resist gap formation under cyclic loading.

Study Design

Controlled laboratory study.

Methods

Crescent-shaped defects were created at the infraspinatus tendon insertion in 32 bovine shoulders. Four arthroscopic suture configurations were tested (8 specimens in each group): simple (group 1), horizontal mattress (group 2), locked mattress (group 3), and locked inverted mattress (group 4). A metal corkscrew suture anchor doubly loaded with No. 2 Fiberwire suture was used for the repairs. A cyclic loading protocol with application of forces from 10 to 180 N for a maximum of 2500 cycles was used. The number of cycles required to form gaps of 5 mm and 10 mm was recorded.

Results

The locked mattress configuration (group 3) outperformed all other groups in resisting 5-mm gap formation (P <. 0001), requiring a mean of 628 cycles in comparison to 65, 193, and 197 cycles for groups 1, 2, and 4, respectively. Both locked configurations (groups 3 and 4) were superior to traditional simple and horizontal mattress configurations in resisting 10-mm gap formation.

Conclusion

The locked mattress suturing technique (group 3) provided the most secure tendon fixation of all arthroscopic configurations tested.

Clinical Relevance

The use of locked suture configurations for arthroscopic rotator cuff repairs may enhance tendon fixation and limit gap formation in the early postoperative period.
Tendon Healing in a Bone Tunnel Differs at the Tunnel Entrance versus the Tunnel Exit
Authors: Rodeo Scott A. , Kawamura Sumito , Kim Hyon-Jeong , Dynybil Christian , Ying Liang
Published: July 2006

Background

Motion between a tendon graft and bone tunnel may impair graft incorporation and lead to tunnel widening.

Hypothesis

Healing of a tendon graft in a bone tunnel is inhibited by graft-tunnel motion.

Study Design

Controlled laboratory study.

Methods

Anterior cruciate ligament reconstruction was performed in 5 cadaveric rabbit limbs, and 3-dimensional graft-tunnel motion was measured using micro–computed tomography. The authors then performed bilateral anterior cruciate ligament reconstruction in 15 rabbits and used histomorphometry to compare tendon-to-bone healing between the tunnel aperture, midtunnel, and tunnel exit and between the anterior and posterior aspects of the tunnel.

Results

Graft-tunnel motion was greatest at the tunnel apertures and least at the tunnel exit in cadaveric testing. Healing of the graft was slowest at the tunnel apertures. Tendon-bone interface width was greater at the aperture than at the tunnel exit for the femoral tunnel (P =. 04). There was an inverse correlation between time zero graft-tunnel motion and healing in the femoral tunnel (P =. 005). There was closer apposition of new bone to the tendon graft in the posterior half of the interface (P <. 05). Osteoclasts were found at the tunnel apertures.

Conclusion

Although graft-tunnel motion was only measured in cadaveric animals, results suggest that healing may be affected by the local mechanical environment, as graft healing in the femoral tunnel was inversely proportional to the magnitude of grafttunnel motion.

Clinical Relevance

Graft-tunnel motion may impair early graft incorporation and may lead to osteoclast-mediated bone resorption, contributing to tunnel widening. Early, aggressive postoperative rehabilitation may have detrimental effects on graft-to-bone healing.
Magnetic Resonance Imaging Abnormalities in Symptomatic and Contralateral Knees
Authors: Boks Simone S. , Vroegindeweij Dammis , Koes Bart W. , Hunink Myriam M. G. M. , Bierma-Zeinstra Sita M. A.
Published: July 2006

Background

After trauma, internal knee lesions are found in approximately two thirds of patients. However, magnetic resonance imaging abnormalities have also been described in asymptomatic volunteers.

Hypothesis

Not all visualized lesions in symptomatic posttraumatic knees are the result of recent trauma; there are subgroups of lesions that may be preexistent.

Study Design

Cross-sectional study (prevalence); Level of evidence, 2.

Methods

Patients visiting their general practitioners after knee trauma were invited for magnetic resonance imaging of both knees. Prevalence of knee abnormalities was compared between symptomatic and asymptomatic knees. Multivariable analysis was performed to investigate the association between lesions that were seen in symptomatic and asymptomatic knees (ie, effusion and meniscal tears) and recent trauma, history of old trauma, age, and osteoarthritis.

Results

In 134 participants, ligament lesions were found almost exclusively in symptomatic knees. Meniscal lesions and effusion were almost equally found in symptomatic and asymptomatic knees. Effusion was related to recent trauma (odds ratio, 14.0; 95% confidence interval, 5.0-39.6) and osteoarthritis (odds ratio, 4.7; 95% confidence interval, 1.4-15.5) but not to history of old trauma and age. Meniscal tears were more common in older patients (odds ratio, 1.09; 95% confidence interval, 1.05-1.12) but were not related to osteoarthritis. History of old trauma was more strongly related to the group of radial, longitudinal, and complex meniscal tears (odds ratio, 8.6; 95% confidence interval, 3.3-22.5) than to horizontal tears (odds ratio, 2.3; 95% confidence interval, 0.9-5.6). Recent trauma was not related to horizontal meniscal tears but was strongly related to other types of meniscal tears (odds ratio, 3.2; 95% confidence interval, 1.4-6.9).

Conclusion

Ligament knee lesions are most probably the result of recent trauma. Radial, longitudinal, and complex meniscal tears are strongly related to trauma, whereas horizontal meniscal tears and effusion may be preexistent in many cases.
Clock-Gated Photic Stimulation of Timeless Expression at Cold Temperatures and Seasonal Adaptation in Drosophila
Authors: Chen Wen-Feng , Majercak John , Edery Isaac
Published: July 2006

Numerous lines of evidence indicate that the initial photoresponse of the circadian clock in Drosophila melanogaster is the light-induced degradation of TIMELESS (TIM). This posttranslational mechanism is in sharp contrast to the well-characterized pacemakers in mammals and Neurospora, where light evokes rapid changes in the transcriptional profiles of 1 or more clock genes. The authors show that light has novel effects on D. melanogaster circadian pacemakers, acutely stimulating the expression of tim at cold but not warm temperatures. This photoinduction occurs in flies defective for the classic visual phototransduction pathway or the circadian-relevant photoreceptor CRYPTOCHROME (CRY). Cold-specific stimulation of tim RNA abundance is regulated at the transcriptional level, and although numerous lines of evidence indicate that period ( per) and tim expression are activated by the same mechanism, light has no measurable acute effect on per mRNA abundance. Moreover, light-induced increases in the levels of tim RNA are abolished or greatly reduced in the absence of functional CLOCK (CLK) or CYCLE (CYC) but not PER or TIM. These findings add to a growing number of examples where molecular and behavioral photoresponses in Drosophila are differentially influenced by “positive” (e.g., CLK and CYC) and “negative” (e.g., PER and TIM) core clock elements. The acute effects of light on tim expression are temporally gated, essentially restricted to the daily rising phase in tim mRNA levels. Because the start of the daily upswing in tim expression begins several hours after dawn in long photoperiods (day length), this gating mechanism likely ensures that sunrise does not prematurely stimulate tim expression during unseasonally cold spring/summer days. The results suggest that the photic stimulation of tim expression at low temperatures is part of a seasonal adaptive response that helps advance the phase of the clock on cold days, enabling flies to exhibit preferential daytime activity despite the (usually) earlier onset of dusk. Taken together with prior findings, the ability of temperature and photoperiod to adjust trajectories in the rising phases of 1 or more clock RNAs constitutes a major mechanism contributing to seasonal adaptation of clock function.
Expression of the Circadian Clock-Related Gene pex in Cyanobacteria Increases in Darkness and Is Required to Delay the Clock
Authors: Takai Naoki , Ikeuchi Shingo , Manabe Katsushi , Kutsuna Shinsuke
Published: July 2006

The time measurement system of the unicellular cyanobacterium Synechococcus elongatus PCC 7942 is analogous to the circadian clock of eukaryotic cells. Circadian clock-related genes have been identified in this strain. The clock-related gene pex is thought to maintain the normal clock period because constitutive transcription or deficiency of this gene causes respectively longer (~28 h) or shorter (~24 h) circadian periods than that of the wild type (~25 h). Here, the authors report other properties of pex in the circadian system. Levels of pex mRNA increased significantly in a 12-h exposure to darkness. Western blotting with a GST-Pex antibody revealed a 13.5-kDa protein band in wild-type cells that were incubated in the dark, while this protein was not detected in pex-deficient mutant cells. Therefore, the molecular weight of the Pex protein appears to be 13.5 kDa in vivo. The PadR domain, which is conserved among DNA-binding transcription factors in lactobacilli, was found in Pex. In the pex mutant, several 12-h light/12-h dark cycles reset the phase of the clock by 3 h earlier (phase advance) compared to wild-type cells. The degree of the advance in the pex mutant was proportional to the number of exposed light-dark cycles. In addition, ectopic induction of pex with an inducible Escherichia coli promoter, Ptrc, delayed the phase in the examined recombinant cells by 2.5 h (phase delay) compared to control cells. These results suggest that the dark-responsive gene expression of pex delays the circadian clock under daily light-dark cycles.
Asymmetric Control of Short Day Response in European Hamsters
Authors: Monecke Stefanie , Malan André , Wollnik Franziska
Published: July 2006

The European hamster ( Cricetus cricetus) is a circannual species in which the synchronization of the circannual cycle to the natural year occurs during 2 annual phases of sensitivity. Around the summer solstice, the animals are sensitive to a shortening of photoperiod. During this sensitive phase, pronounced changes in circadian output parameters are observed, indicating a different functional state of the circadian system. This special state is assumed to be necessary to develop the extreme sensitivity to short day length in European hamsters during this phase. In natural conditions, the animals are able to recognize the shortening of photoperiod already in mid-July, when the photoperiod is reduced only by 30 min. To investigate the short-day response in sensitive European hamsters on the basis of the 2-coupled oscillator model of Pittendrigh and Daan (1976), daily activity and the reproductive state of European hamsters were recorded after an asymmetrical reduction of photoperiod from long (LD 16:08) to short (LD 08:16) photoperiods. The activity pattern of the animals showed an immediate response to the short photoperiod at the day of transfer when the night was extended only into the evening, but there was a significant delay in the response time when the night was extended into the morning. Thus, the evening oscillator E is more important in inducing the photoperiodic response than the morning oscillator M. Moreover, the broad intragroup variation in the latter conditions strongly suggests that the changes in the activity pattern were endogenously induced and that the animals were not able to recognize a lengthening of the night into the morning. Gonadal regression started in both groups 3 weeks after the change in the activity pattern, indicating that this process is initiated when the circadian system has received the short-day signal either through changes in photoperiod or through the circannual clock.
Simulation of Day-Length Encoding in the SCN: From Single-Cell to Tissue-Level Organization
Authors: Rohling Jos , Wolters Lex , Meijer Johanna H.
Published: July 2006

The circadian pacemaker of the SCN is a heterogeneous structure containing many single-cell oscillators that display phase differences in gene expression and electrical activity rhythms. Thus far, it is unknown how single neurons contribute to the population signal measured from the SCN. The authors used single-unit electrical activity rhythms that have previously been recorded in SCN slices and investigated in simulation studies how changes in pattern shape and distribution of single neurons alter the ensemble activity rhythm of the SCN. The results were compared with recorded ensemble rhythms. The simulations show that single units should be distributed in phase to render the recorded multiunit waveform and that different distributions can account for the multiunit pattern of the SCN, including a bimodal distribution. Vice versa, the authors show that the single-unit distribution cannot be inferred from the ensemble pattern. Photoperiodic encoding by the SCN relies on changes in waveform of the neuronal output from the SCN and received special attention in this study’s simulations. The authors show that a broadening or narrowing of the multiunit pattern can be based on changes in phase differences between neurons, as well as on changes in the circadian pattern of individual neurons. However, these mechanisms give rise to differences in the maximal discharge level of the multiunit pattern, leading to testable predictions to distinguish between the 2 mechanisms. If single units broaden their activity pattern in long days, the maximum frequency of the multiunit activity should increase, while an increase in phase difference between the single-unit activity rhythms should lead to a decrement in maximum frequency. The simulations also show that coding for day-length by an evening and morning oscillator is not self-evident and will only work under a limited set of conditions in which the distribution within each component and temporal distance between the components is taken into account. While the simulations were based on single-cell and multiunit electrical activity patterns, they are also relevant for understanding the relation between single-cell and population molecular expression profiles.
Ectopic CRYPTOCHROME Renders TIM Light Sensitive in the Drosophila Ovary
Authors: Rush Brandy L. , Murad Alejandro , Emery Patrick , Giebultowicz Jadwiga M.
Published: July 2006

The period ( per) and timeless ( tim) genes play a central role in the Drosophila circadian clock mechanism. PERIOD (PER) and TIMELESS (TIM) proteins periodically accumulate in the nuclei of pace-making cells in the fly brain and many cells in peripheral organs. In contrast, TIM and PER in the ovarian follicle cells remain cytoplasmic and do not show daily oscillations in their levels. Moreover, TIM is not light sensitive in the ovary, while it is highly sensitive to this input in circadian tissues. The mechanism underlying this intriguing difference is addressed here. It is demonstrated that the circadian photoreceptor CRYPTOCHROME (CRY) is not expressed in ovarian tissues. Remarkably, ectopic cry expression in the ovary is sufficient to cause degradation of TIM after exposure to light. In addition, PER levels are reduced in response to light when CRY is present, as observed in circadian cells. Hence, CRY is the key component of the light input pathway missing in the ovary. However, the factors regulating PER and TIM levels downstream of light/cry action appear to be present in this non-circadian organ.