bluuebunny/crossref_metadata_2025 huggingface dataset:
Assembly of High-Density Lipoprotein
Authors: Yokoyama Shinji
Published: November 2005

Mammalian somatic cells do not catabolize cholesterol and need to export it for its homeostasis at the levels of cells and whole bodies. This reaction may reduce intracellularly accumulated cholesterol in excess and would contribute to prevention or regression of the initial stage of atherosclerosis. High-density lipoprotein (HDL) is thought to play a main role in this reaction, and 2 independent mechanisms are proposed for this reaction. First, cholesterol is exchanged in a nonspecific physicochemical manner between cell surface and extracellular lipoproteins, and cholesterol esterification on HDL provides a driving force for net removal of cell cholesterol. Second, apolipoproteins directly interact with cells and generate HDL by removing cellular phospholipid and cholesterol. This reaction is a major source of plasma HDL and is mediated by a membrane protein, ABCA1. Lipid-free or lipid-poor helical apolipoproteins primarily recruit cellular phospholipid to assemble HDL particles, and cholesterol enrichment in these particles is regulated independently. ABCA1 is a rate-limiting factor of the HDL assembly and is regulated by transcriptional factors and posttranscriptional factors. Posttranscriptional regulation of ABCA1 includes modulation of its calpain-mediated degradation.
Effects of Pioglitazone on Lipoproteins, Inflammatory Markers, and Adipokines in Nondiabetic Patients with Metabolic Syndrome
Authors: Szapary Philippe O. , Bloedon LeAnne T. , Samaha Frederick F. , Duffy Danielle , Wolfe Megan L. , Soffer Daniel , Reilly Muredach P. , Chittams Jesse , Rader Daniel J.
Published: November 2005

Objective—

The purpose of this research was to evaluate the short-term effects of pioglitazone (PIO) on high-density lipoprotein cholesterol (HDL-C) and other metabolic parameters in nondiabetic patients with metabolic syndrome (MetSyn).

Methods and Results—

Sixty nondiabetic adults with low HDL-C and MetSyn were randomized to PIO or matching placebo for 12 weeks. PIO increased HDL-C by 15% and 14% at 6 and 12 weeks, respectively, compared with placebo (
P
<0.001). Changes in HDL-C were correlated to changes in adiponectin (
r
=0.34;
P
=0.01) but not to changes in insulin resistance. PIO did not affect serum triglycerides or low-density lipoprotein (LDL) cholesterol concentrations but reduced the number of small LDL particles by 18% (
P
<0.001). PIO reduced median C-reactive protein levels by 31% (
P
<0.001) and mean resistin levels by 10% (
P
=0.02) while increasing mean serum levels of adiponectin by 111% (
P
<0.001) compared with placebo. PIO did not affect weight and modestly decreased insulin resistance.

Conclusions—

In nondiabetic patients with low HDL-C and MetSyn, PIO significantly raised HDL-C and favorably affected lipoprotein particle size, markers of inflammation, and adipokines without changes in triglycerides, LDL-C, or weight. These results suggest that PIO has direct effects on HDL, which may contribute to its antiatherogenic effects.
Identification of Macrophage Arginase I as a New Candidate Gene of Atherosclerosis Resistance
Authors: Teupser Daniel , Burkhardt Ralph , Wilfert Wolfgang , Haffner Ivonne , Nebendahl Klaus , Thiery Joachim
Published: November 2005

Objective—Our laboratory has previously created 2 strains of rabbits with genetically determined high-atherosclerotic response (HAR) and low-atherosclerotic response (LAR). The aim of the present study was to identify new genes of atherosclerosis susceptibility in macrophages from the 2 strains.

Methods and Results—Suppression subtractive hybridization was used to screen for genes with higher expression in macrophages from LAR rabbits. We identified a cDNA fragment with high homology to human arginase I (AI; 91%) and subsequently cloned the full-length cDNA of the rabbit homologue. Quantitative RT-PCR revealed a significantly higher macrophage AI mRNA expression in LAR rabbits than in HAR rabbits (77428±10941 versus 34344±4538;P=0.002; copies/106copies β-actin), which also correlated with a significantly higher arginase enzyme activity. Northern blot analysis led to the identification of a size polymorphism of AI mRNA. This was because of a 413 bp C-repeat insertion in the 3′ untranslated region. The shorter transcript variant was predominantly expressed in LAR rabbits and associated with significantly higher AI mRNA expression levels. Transfection experiments indicated decreased mRNA stability of the long AI variant.

Conclusions—High expression of arginase I in macrophages may contribute to atherosclerosis resistance of LAR rabbits, possibly by conferring antiinflammatory effects in the vessel wall.
Gab1, SHP2, and Protein Kinase A Are Crucial for the Activation of the Endothelial NO Synthase by Fluid Shear Stress
Authors: Dixit Madhulika , Loot Annemarieke E. , Mohamed Annisuddin , Fisslthaler Beate , Boulanger Chantal M. , Ceacareanu Bogdan , Hassid Aviv , Busse Rudi , Fleming Ingrid
Published: November 2005

Fluid shear stress enhances NO production in endothelial cells by a mechanism involving the activation of the phosphatidylinositol 3-kinase and the phosphorylation of the endothelial NO synthase (eNOS). We investigated the role of the scaffolding protein Gab1 and the tyrosine phosphatase SHP2 in this signal transduction cascade in cultured and native endothelial cells. Fluid shear stress elicited the phosphorylation and activation of Akt and eNOS as well as the tyrosine phosphorylation of Gab1 and its association with the p85 subunit of phosphatidylinositol 3-kinase and SHP2. Overexpression of a Gab1 mutant lacking the pleckstrin homology domain abrogated the shear stress–induced phosphorylation of Akt but failed to affect the phosphorylation or activity of eNOS. The latter response, however, was sensitive to a protein kinase A (PKA) inhibitor. Mutation of Gab1 Tyr627 to phenylalanine (YF-Gab1) to prevent the binding of SHP2 completely prevented the shear stress–induced phosphorylation of eNOS, leaving the Akt response intact. A dominant-negative SHP2 mutant prevented the activation of PKA and phosphorylation of eNOS without affecting that of Akt. Moreover, shear stress elicited the formation of a signalosome complex including eNOS, Gab1, SHP2 and the catalytic subunit of PKA. In isolated murine carotid arteries, flow-induced vasodilatation was prevented by a PKA inhibitor as well as by overexpression of either the YF-Gab1 or the dominant-negative SHP2 mutant. Thus, the shear stress–induced activation of eNOS depends on Gab1 and SHP2, which, in turn, regulate the phosphorylation and activity of eNOS by a PKA-dependent but Akt-independent mechanism.
Inhibition of Brain GTP Cyclohydrolase I and Tetrahydrobiopterin Attenuates Cerebral Infarction via Reducing Inducible NO Synthase and Peroxynitrite in Ischemic Stroke
Authors: Kidd Grant A. , Hong Hua , Majid Arshad , Kaufman David I. , Chen Alex F.
Published: November 2005

Background—

Inducible NO synthase (NOS)–derived peroxynitrite (ONOO
−
) during ischemia/reperfusion contributes to ischemic brain injury. However, inducible NOS (iNOS) regulation in ischemic stroke remains unknown. Tetrahydrobiopterin (BH
4
) is an essential cofactor for NOS activity. The present study tested the hypothesis that inhibition of endogenous BH
4
rate-limiting enzyme GTP cyclohydrolase I (GTPCH I), and thus BH
4
synthesis, reduces cerebral infarction via inhibiting iNOS and ONOO
−
in transient focal ischemia.

Methods—

Focal ischemia (2 hours) was created in adult male Sprague-Dawley rats (250 to 300 g) by middle cerebral artery occlusion (MCAO). Rats were treated 12 hours before MCAO with vehicle or diamino-6-hydroxypyrimidine (DAHP; 0.5 g/kg IP), a selective GTPCH I inhibitor. Brains were harvested 24 hours after reperfusion for assays of infarct volume, blood–brain barrier (BBB) permeability, GTPCH I activity, BH
4
levels, GTPCH I and NOS mRNA, protein expression, and superoxide anion (O
2
·
−
) and ONOO
−
levels.

Results—

Endogenous GTPCH I activity, BH
4
levels, iNOS activity, and (O
2
·
−
and ONOO
−
levels were all augmented after ischemia/reperfusion. DAHP treatment significantly reduced GTPCH I activity, resulting in decreased BH
4
levels, iNOS activity, and ONOO
−
levels. Consequently, DAHP treatment significantly reduced the infarct size compared with the nontreated group (22.3±5.6 versus 38.3±7.4%; n=6;
P
<0.05). Similarly, BBB permeability was significantly reduced after DAHP pretreatment compared with the control group (4.11±0.22 versus 7.78±0.44 μg/g tissue; n=5;
P
<0.05).

Conclusion—

These results demonstrate that blockade of endogenous brain BH
4
synthesis attenuates cerebral infarction via inhibiting iNOS and ONOO
−
, which may provide a mechanistic basis of novel therapeutic strategies for ischemic stroke.
Bone Marrow Stromal Cells That Enhanced Fibroblast Growth Factor-2 Secretion by Herpes Simplex Virus Vector Improve Neurological Outcome After Transient Focal Cerebral Ischemia in Rats
Authors: Ikeda Naokado , Nonoguchi Naosuke , Zhao Ming Zhu , Watanabe Takuji , Kajimoto Yoshinaga , Furutama Daisuke , Kimura Fumiharu , Dezawa Mari , Coffin Robert S. , Otsuki Yoshinori , Kuroiwa Toshihiko , Miyatake Shin-Ichi
Published: November 2005

Background and Purpose—

Fibroblast growth factor-2 (FGF-2) administration and bone marrow stromal cell (MSC) transplantation could improve neurological deficits after occlusive cerebrovascular disease. In the present study, we examined the effects of neurological improvement after transient middle cerebral artery occlusion (MCAO) in rats by a novel therapeutic strategy with FGF-2 gene–transferred MSCs by the herpes simplex virus type 1 (HSV-1) vector.

Methods—

Adult Wistar rats were anesthetized. Nonmodified MSCs, FGF-2–modified MSCs with HSV-1 1764/-4/pR19/ssIL2-FGF-2, or PBS was administered intracerebrally 24 hours after transient right MCAO. All animals underwent behavioral tests for 21 days, and the infarction volume with 2-3-5-triphenylterazolium was detected 3 days and 14 days after the MCAO. Three days and 7 days after the MCAO, the FGF-2 production in the ipsilateral hemisphere of the MCAO was measured with ELISA. Seven and 14 days after the MCAO, immunohistochemical staining for FGF-2 was applied.

Results—

The stroke animals receiving FGF-2–modified MSCs demonstrated significant functional recovery compared with the other groups. Fourteen days after the MCAO, there was a significant reduction in infarction volume only in FGF-2–modified MSC-treated group. FGF-2 production in the FGF-2–modified MSC-treated brain was significantly higher compared with the other groups at 3 and 7 days after MCAO. Administrated FGF-2–modified MSCs strongly expressed the FGF-2 protein, which was proven by ELISA.

Conclusions—

Our data suggest that the FGF-2 gene–modified MSCs with the HSV-1 vector can contribute to remarkable functional recovery after stroke compared with MSCs transplantation alone.
Systemic Blood Pressure Profile in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy
Authors: Rufa Alessandra , Dotti Maria Teresa , Franchi Massimo , Stromillo Maria Laura , Cevenini Gabriele , Bianchi Silvia , De Stefano Nicola , Federico Antonio
Published: November 2005

Background and Purpose—

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a genetic form of subcortical ischemic vascular dementia (SIVD). The most common vascular risk factors are unremarkable in CADASIL; however, studies on systemic blood pressure (BP) changes over time are substantially lacking. Because BP instability is a relevant risk factor for developing or worsening white matter changes in sporadic SIVD, we aimed to study the BP profile of CADASIL to investigate its relationship with cognitive decline and white matter injury.

Methods—

Twenty-four–hour ambulatory BP monitoring was performed in a group of 14 CADASIL patients (12 males and 2 females) and in a group of 15 healthy age-matched control subjects. The following BP variables were compared between the 2 groups: mean daytime and nighttime systolic, diastolic, and mean arterial BP (SABP
day
, DABP
day
, and MABP
day
, and SABP
night
, DABP
night
, and MABP
night
) and nocturnal percentage decline in arterial BP (%MABP reduction). Cognitive performances were tested by mini mental status examination (MMSE), and brain MRI was performed to extrapolate the T2-weighted lesion volume (LV) in each CADASIL patient. The 24-hour arterial BP variables were compared between CADASIL and controls. In addition, for CADASIL patients only, MMSE, LV, and age were compared with each pressure variable.

Results—

Patients with CADASIL showed a significant reduction (
P
<0.05) of SABP
day
, DABP
day
, MABP
day
and %MABP decline with respect to controls. In addition, MMSE of CADASIL subjects correlated significantly (
P
<0.0001) with daytime MABP.

Conclusions—

The low systemic BP profile observed in CADASIL patients was specifically attributable to reduced diurnal BP values. This may further affect cerebral hemodynamics and increase the risk of cognitive impairment in these patients. The pathogenesis of abnormal BP profile in CADASIL remains to be clarified. It is likely that central and peripheral mechanisms controlling BP variations are involved.
Disparate Associations of a Functional Promoter Polymorphism in
PCK1
With Carotid Wall Ultrasound Traits
Authors: Hegele Robert A. , Al-Shali Khalid Z. , House Andrew A. , Hanley Anthony J.G. , Harris Stewart B. , Mamakeesick Mary , Fenster Aaron , Zinman Bernard , Cao Henian , Spence J. David
Published: November 2005

Background and Purpose—

Cytosolic phosphoenolpyruvate carboxykinase (PEPCK; EC 4.1.1.32), encoded by
PCK1
, catalyzes the first committed step in gluconeogenesis. We previously showed that a –232C>G promoter polymorphism within a
cis
-acting element required for basal and cAMP-mediated
PCK1
gene transcription results in loss of negative regulation by insulin, contributing to worsened metabolic control in the context of insulin resistance. We hypothesized that this polymorphism would be associated with carotid atherosclerosis in a sample of 150 aboriginal Canadians.

Methods—

Dependent variables were 2 distinct carotid traits, namely intima-media thickness (IMT) assessed using B-mode ultrasound and total carotid plaque volume (TPV) assessed using 3D ultrasound.

Results—

Multivariate analysis showed significant but opposite associations of
PCK1
genotype with these traits. Specifically, subjects with the
PCK1
–232G/G genotype had more carotid IMT (0.80±0.02 versus 0.73±0.03 mm;
P
=0.007) but less TPV (0.10±0.09 versus 0.38±0.13;
P
=0.03) than subjects with other genotypes.

Conclusions—

The findings connect the key enzyme in gluconeogenesis with atherosclerosis. The meaning of the opposing associations of
PCK1
genotype with IMT and TPV is unclear; more work is required to confirm whether these might be distinct quantitative traits with different biological determinants.
Plasma Adiponectin Levels and Sonographic Phenotypes of Subclinical Carotid Artery Atherosclerosis
Authors: Iglseder Bernhard , Mackevics Vitolds , Stadlmayer Andreas , Tasch Gernot , Ladurner Gunther , Paulweber Bernhard
Published: November 2005

Background and Purpose—

Adipose tissue produces and secretes a number of bioactive molecules, conceptualized as adipocytokines. Adiponectin has been identified as one of the adipocytokines, and hypoadiponectinemia was demonstrated in patients with obesity, diabetes mellitus, and coronary artery disease. Whether decreased adiponectin levels are cause or consequence is an important issue in the discussion on the association between adiponectin and atherosclerosis. In the present study, we investigated the association of plasma adiponectin levels with sonographic phenotypes of subclinical atherosclerosis, which may represent different stages of disease as well as common and distinct determinants.

Methods—

A total of 1515 middle-aged healthy white subjects (940 males and 575 females) were included. Common carotid artery intima-media thickness (CIMT) and presence of atherosclerotic plaques were assessed by B-mode ultrasound.

Results—

After adjustment for established risk factors, per 1 μg/mL decrease in adiponectin CIMT increased on the average by 3.48 μm in males (95% CI, 1.23 to 5.73 μm) and by 2.39 μm in females (95% CI, 0.50 to 4.27 μm). After dichotomizing adiponectin levels at the median and adjustment for established risk factors, the mean difference of CIMT between subjects with low and high adiponectin levels was 20.42 μm in men (95% CI, 6.80 to 34.04;
P
=0.003) and 20.75 μm in women (95% CI, 1.08 to 40.42;
P
=0.039). No significant relationship was found between adiponectin levels and presence of atherosclerotic plaques.

Conclusion—

Our results demonstrate an independent negative association of adiponectin levels and CIMT, whereas no relationship with presence of atherosclerotic plaques was found, thus suggesting hypoadiponectinemia as a risk factor in the development of early atherosclerosis.
Drug-Eluting Stents for the Treatment of Intracranial Atherosclerosis
Authors: Abou-Chebl Alex , Bashir Qasim , Yadav Jay S.
Published: November 2005

Background and Purpose—

Intracranial stenting is associated with a 32% rate of restenosis. Drug-eluting stents (DES) have revolutionized the treatment of coronary artery disease and have greatly reduced the risk of in-stent stenosis. We present our experience with the feasibility and safety of using DES for patients with symptomatic intracranial atherosclerosis.

Methods—

All of the patients had >70% stenoses and had failed maximal medical therapy. They were pretreated with aspirin, clopidogrel, and intraprocedural heparin. All of the lesions were predilated, and balloons and stents were slightly undersized. Clopidogrel and aspirin were continued for 1 year, and patients had clinical follow-up and vascular imaging at 30 days, 6 months, and 1 year.

Results—

Eight patients with intracranial internal carotid artery (3), middle cerebral (2), basilar (2), and vertebral artery (1) stenoses were successfully treated with 4 Cypher (Cordis Corp) and 4 Taxus (Boston Scientific Inc) stents. The mean stenosis severity was reduced from 84.4%±10.2% to 2.5%±4.6%. One patient had an intraprocedural retinal embolism, but there were no other complications. Over a mean follow-up of 11.1±4.9 months (range, 2 to 17.3 months), patients have had repeat angiography (5) or transcranial Doppler with or without CT angiography (3). None of the patients have had clinical or significant angiographic restenosis or required target vessel revascularization.

Conclusions—

Elective intracranial stenting with DES appears to be feasible and safe, but additional clinical experience is required to assess its efficacy.
The Impact of History of Hypertension and Type 2 Diabetes at Baseline on the Incidence of Stroke and Stroke Mortality
Authors: Hu Gang , Sarti Cinzia , Jousilahti Pekka , Peltonen Markku , Qiao Qing , Antikainen Riitta , Tuomilehto Jaakko
Published: November 2005

Background and Purpose—

Both hypertension and diabetes are strong predictors of stroke, but very few studies have assessed their joint effect on stroke risk. We evaluated prospectively the joint association of history of hypertension and type 2 diabetes on the incidence of stroke and stroke mortality.

Methods—

We prospectively followed 49 582 Finnish subjects aged 25 to 74 years without a history of stroke and coronary heart disease at baseline. Hazards ratios (HRs) for stroke risk were estimated by the hypertension and diabetes status.

Results—

During a mean follow-up of 19.1 years, 2978 incident stroke events were recorded, of which 924 were fatal. Age-, sex-, and study year-adjusted HRs of stroke incidence were 1.35 (95% CI, 1.21 to 1.51), 1.98 (95% CI, 1.79 to 2.19), 2.54 (95% CI, 1.61 to 4.01), 3.51 (95% CI, 2.40 to 5.14), and 4.50 (95% CI, 3.60 to 5.61), respectively, among subjects with hypertension I (blood pressure 140 to 159/90 to 94 mm Hg) only, with hypertension II (blood pressure ≥160/95 mm Hg, or using antihypertensive drugs) only, with diabetes only, with both hypertension I and diabetes, and with both hypertension II and diabetes compared with the subjects without either of the diseases. The corresponding HRs of stroke mortality were 1.47, 2.62, 3.06, 5.59, and 9.27, respectively. Additional adjustments for body mass index, cholesterol, education, smoking, alcohol consumption, and physical activity did not appreciably change these risk estimates. Blood pressure affected the risk of stroke similarly in diabetic and nondiabetic subjects.

Conclusions—

Hypertension and type 2 diabetes increase stroke risk independently, and their combination increases the risk drastically. A significant proportion of the risk of stroke assumed to be related to hypertension may be attributable to concomitant diabetes.
Identification of Culprit Lesions After Transient Ischemic Attack by Combined
18
F Fluorodeoxyglucose Positron-Emission Tomography and High-Resolution Magnetic Resonance Imaging
Authors: Davies John R. , Rudd James H.F. , Fryer Tim D. , Graves Martin J. , Clark John C. , Kirkpatrick Peter J. , Gillard Jonathan H. , Warburton Elizabeth A. , Weissberg Peter L.
Published: November 2005

Background and Purpose—

Carotid endarterectomy is currently guided by angiographic appearance on the assumption that the most stenotic lesion visible at angiography is likely to be the lesion from which future embolic events will arise. However, risk of plaque rupture, the most common cause of atherosclerosis-related thromboembolism, is dictated by the composition of the plaque, in particular the degree of inflammation. Angiography may, therefore, be an unreliable method of identifying vulnerable plaques. In this study, plaque inflammation was quantified before endarterectomy using the combination of
18
F fluorodeoxyglucose positron (FDG)-emission tomography (PET) and high-resolution MRI (HRMRI).

Methods—

Twelve patients, all of whom had suffered a recent transient ischemic attack, had a severe stenosis in the ipsilateral carotid artery, and were awaiting carotid endarterectomy underwent FDG-PET and HRMRI scanning. A semiquantitative estimate of plaque inflammation was calculated for all of the lesions identified on HRMRI.

Results—

In 7 of 12 patients (58%), high FDG uptake was seen in the lesion targeted for endarterectomy. In the remaining 5 patients, FDG uptake in the targeted lesion was low. In these 5 patients, 3 had nonstenotic lesions identified on HRMRI that exhibited a high level of FDG uptake. All 3 of the highly inflamed nonstenotic lesions were located in a vascular territory compatible with the patients’ presenting symptoms.

Conclusions—

Our data suggest that angiography may not always identify the culprit lesion. Combined FDG-PET and HRMRI can assess the degree of inflammation in stenotic and nonstenotic plaques and could potentially be used to identify lesions responsible for embolic events.
First-Ever Stroke Incidence and 30-Day Case Fatality in the Sicilian Aeolian Archipelago, Italy
Authors: Musolino Rosa , La Spina Paolino , Serra Salvatore , Postorino Paolo , Calabró Salvatore , Savica Rodolfo , Salemi Giovanni , Gallitto Giuseppe
Published: November 2005

Background and Purpose—

Not many data on stroke epidemiology come from studies on islands. This is the first report on a Mediterranean archipelago population.

Methods—

Using recommended criteria, from July 1, 1999, to June 30, 2002, information was collected on first-ever stroke and 30-day case fatality in Aeolian island residents (13 431).

Results—

The overall crude incidence rate was 154 of 100 000 (95% CI, 118 to 197; 128 in men and 180 in women) or 180, 154, and 87, if adjusted to the Italian, European, and world populations, respectively. The 30-day case fatality rate was 24.2% (95% CI, 14.22 to 36.75).

Conclusions—

Besides genetic or dietary factors, our results may reflect local, limited possibilities of diagnosis and management for stroke patients.
The Independent and Interactive Effects of Embodied-Agent Appearance and Behavior on Self-Report, Cognitive, and Behavioral Markers of Copresence in Immersive Virtual Environments
Authors: Bailenson Jeremy N. , Swinth Kim , Hoyt Crystal , Persky Susan , Dimov Alex , Blascovich Jim
Published: November 2005

The current study examined how assessments of copresence in an immersive virtual environment are influenced by variations in how much an embodied agent resembles a human being in appearance and behavior. We measured the extent to which virtual representations were both perceived and treated as if they were human via self-report, behavioral, and cognitive dependent measures. Distinctive patterns of findings emerged with respect to the behavior and appearance of embodied agents depending on the definition and operationalization of copresence. Independent and interactive effects for appearance and behavior were found suggesting that assessing the impact of behavioral realism on copresence without taking into account the appearance of the embodied agent (and vice versa) can lead to misleading conclusions. Consistent with the results of previous research, copresence was lowest when there was a large mismatch between the appearance and behavioral realism of an embodied agent.
Evoking Affordances in Virtual Environments via Sensory-Stimuli Substitution
Authors: Gross David C. , Stanney Kay M. , Cohn Lt. Joseph
Published: November 2005

Artifacts in an environment afford to their observers utility and function directly through specific object characteristics (e.g., mediums, surfaces, substances). Virtual environments (VEs) similarly seek to afford specific utility to their users, whether it is for training, education, or entertainment, thus it seems natural to consider basing VE designs on affordances. Such affordance-based design should yield significant benefits by providing designs that behave in more understandable and intuitive manners. These designs should be easier to learn, adapt better to user tasks, and frustrate users less by allowing use of the same skills acquired via real-world interactions. In order to realize affordance-based VE designs, the types of appropriate affordances and means of realizing these affordances must be identified. Currently, however, affordances lack a theoretical and operational basis for such application. The present paper suggests functions that affordances should support and provides a conceptual model for realizing affordances based on sensory-stimuli-substitution schemes.
Effects of Communication Mode on Social Presence, Virtual Presence, and Performance in Collaborative Virtual Environments
Authors: Sallnäs Eva-Lotta
Published: November 2005

How does communication mode affect people's experience of social presence, presence, and performance, and how does it affect their actual collaboration in a virtual environment? In a first experiment, subjects communicated by text-chat, audio conference, or video conference in a desktop collaborative virtual environment (CVE). Both perceived social presence and presence were shown to be lower in the text-chat condition than in the audio- and video-conference conditions. People spent a longer time performing a decision-making task together, spoke fewer words in total, and also spoke fewer words per second in the text-chat environment. Finally, more words per second were spoken in the audio-conference than in the video-conference condition. In a second experiment, collaboration in a CVE audio- and a CVE video condition was compared to collaboration in a Web audio-conference and a Web video-conference condition. Results showed that presence was rated higher in the two video than in the two audio conditions and especially in the Web video condition. People spent more time in the video than in the audio conditions and more words per second were spoken in the Web than in the CVE conditions. In conclusion, it was found that both the communication media used and the environment in which collaboration takes place (CVE or Web) make a difference for how subjects experience interaction and for their communication behavior.
The Perception of Walking Speed in a Virtual Environment
Authors: Banton Tom , Stefanucci Jeanine , Durgin Frank , Fass Adam , Proffitt Dennis
Published: November 2005

Studies of locomotion in virtual environments assume that correct geometric principles define the relationship between walking speed and environmental flow. However, we have observed that geometrically correct optic flow appears to be too slow during simulated locomotion on a treadmill. Experiment 1 documents the effect in a head-mounted display. Experiment 2 shows that the effect is eliminated when the gaze is directed downward or to the side, or when the walking speed is slow. Experiment 3 shows that the effect is unchanged by stride length. Experiment 4 verifies that the effect is not attributable to image jitter. The change in perceived speed from straight ahead to side or down gaze coincides with a shift from expanding optic flow to lamellar flow. Therefore, we hypothesize that lamellar flow is necessary for accurate speed perception, and that a limited field of view eliminates this cue during straight-ahead gaze.
Perceived Instability of Virtual Haptic Texture. II. Effect of Collision-Detection Algorithm
Authors: Choi Seungmoon , Tan Hong Z.
Published: November 2005

This article reports the second study in a series that investigates perceived instability—unrealistic sensations associated with virtual objects—of virtual haptic texture. Our first study quantified the maximum stiffness values under which virtual haptic textures were perceived to be stable (Choi & Tan, 2004). The present study investigated the effect of the collision-detection algorithm by removing the step changes in force magnitude that could have contributed to perceived instability in the first study. Our results demonstrate a significant increase in the maximum stiffness for stable haptic texture rendering. We also report a new type of perceived instability, aliveness, that is characterized by a pulsating sensation. We discuss the possible cause of aliveness and show that it is not always associated with control instability. Our results underscore the important roles played by environment modeling and human haptic perception, as well as control stability, in ensuring a perceptually stable virtual haptic environment.
Being on Guard: Intelligent Virtual Agents Reporting Information from Collaborative Virtual Environments
Authors: Herrero Pilar , Greenhalgh Chris , Antonio Angélica de
Published: November 2005

An important property of intelligent virtual agents (IVAs) and multiintelligent virtual agents systems (mIVAS) is their capability to acquire/perceive information from their environment. In this paper we present an auditory perceptual model for IVAs and mIVAS, which extends and reinterprets the key concepts of one of the awareness models developed for computer supported cooperative work (CSCW) applications, the spatial model of interaction (SMI). This perceptual model also introduces some factors typical of human perception—such as auditory acuity—as well as others associated with the sound source and its propagation with the aim of making perception in this kind of system more humanlike.
Effect of Variations in Sensory Feedback on Performance in a Virtual Reaching Task
Authors: Durlach Paula J. , Fowlkes Jennifer , Metevier Christopher J.
Published: November 2005

An experiment was conducted to investigate whether manipulation of the sensory cues provided in a virtual-reality context would affect performance of a reaching task and its associated phenomenology. Performance was measured by speed (the time taken to reach out and touch a virtually presented visual target) and accuracy (the distance of the fingertip from the center of the virtual target). Phenomenological experience was measured via questionnaires. The cues manipulated were the visual realism of the virtual hand (fidelity), whether the virtual fingertip was seen to penetrate the virtual target or not (constraint), and whether the feedback given on contact with the virtual target was tactile or auditory (feedback). We found that better hand fidelity speeded movement, increased presence, and reduced disorientation. In contrast, the constraint manipulation affected touch accuracy and disorientation. Tactile feedback enhanced the sense of presence and reduced disorientation, compared with auditory feedback.
When “Real” Seems Mediated: Inverse Presence
Authors: Timmins Lydia Reeves , Lombard Matthew
Published: November 2005

As our lives become increasingly dominated by mediated experiences, presence scholars have noted that an increasing number of these mediated experiences evoke (tele)-presence, perceptions that ignore or misconstrue the role of the medium in the experience. In this paper we explore an interesting countertrend that seems to be occurring as well. In a variety of contexts, people are experiencing not an illusion that a mediated experience is in fact nonmediated, but the illusion that a nonmediated “real” experience is mediated. Drawing on news reports and an online survey, we identify 3 categories of this “illusion of mediation”: positive (when people perceive natural beauty as mediated), negative (when people perceive a disaster, crime, or other tragedy such as the events of September 11, 2001, as mediated), and unusual (when close connections between people's “real life” activities and mediated experiences lead them to confuse the former with the latter). We label this phenomenon inverse presence and consider its place and value in a comprehensive theory of presence, its possible antecedents and consequences, and what it suggests about the nature of our lives in the 21st century.
A Convenient Multicamera Self-Calibration for Virtual Environments
Authors: Svoboda Tomáš , Martinec Daniel , Pajdla Tomáš
Published: November 2005

Virtual immersive environments or telepresence setups often consist of multiple cameras that have to be calibrated. We present a convenient method for doing this. The minimum is three cameras, but there is no upper limit. The method is fully automatic and a freely moving bright spot is the only calibration object. A set of virtual 3D points is made by waving the bright spot through the working volume. Its projections are found with subpixel precision and verified by a robust RANSAC analysis. The cameras do not have to see all points; only reasonable overlap between camera subgroups is necessary. Projective structures are computed via rank-4 factorization and the Euclidean stratification is done by imposing geometric constraints. This linear estimate initializes a postprocessing computation of nonlinear distortion, which is also fully automatic. We suggest a trick on how to use a very ordinary laser pointer as the calibration object. We show that it is possible to calibrate an immersive virtual environment with 16 cameras in less than 60 minutes reaching about 1/5 pixel reprojection error. The method has been successfully tested on numerous multicamera environments using varying numbers of cameras of varying quality.
Picking the Wrong Fight: Why Attacks on the World Trade Organization Pose the Real Threat to National Environmental and Public Health Protection
Authors: Young Alasdair R.
Published: November 2005

A principal reason for popular concern about the World Trade Organisation is that national rules—especially those for environmental and public health pro-tection—may be overturned because they are incompatible with the WTO's rules. This article argues that while these concerns are not totally unfounded, they are exaggerated. A central reason for this exaggeration is that environmental and consumer advocates discount the pivotal role of governments in the dispute resolution process. Governments agree to the multilateral rules in the first place. Governments decide which market access barriers to pursue and how aggressively. Governments determine how to comply with a WTO judgment that goes against them. Furthermore, this article contends that by exaggerating the constraint imposed upon national governments by the WTO, consumer and environmental advocates run the risk of actually discouraging the very environmental and public health regulations they favor.
The Cartagena Protocol on Biosafety and Shifts in the Discourse of Precaution
Authors: Andrée Peter
Published: November 2005

The precautionary principle is increasingly recognized as an important tool in multilateral environmental policy making, even as its practical implications remain the subject of intense debate. Drawing on Foucault's reading of discursive politics, this paper traces the emergence and effects of a specific framing of a precautionary response to new technologies found in the 2000 Cartagena Protocol on Biosafety to the Convention on Biological Diversity. This international treaty enables states to restrict imports of specific classes of genetically modified organisms (GMOs), even if the extent of the harm they may cause remains uncertain. This particular framing of precaution in an environmental treaty is novel for its application to technologies yet to be demonstrated as harmful, and can only be understood in the context of the contentiousness of controversies over GMOs, bovine spongiform encephalopathy (BSE), and hormone-injected beef in the 1990s. At the same time, what might be termed the “Cartagena discourse of precaution” has already had productive effects on a variety of other policy fields including the regulation of persistent organic pollutants and pesticides.
How Transnational Environmental Advocacy Networks Socialize International Financial Institutions: A Case Study of the International Finance Corporation
Authors: Park Susan
Published: November 2005

Environmental organizations, characterized here as transnational advocacy networks, use various strategies to “green” international financial institutions (IFIs). This article goes beyond analyzing network strategies to examine how transnational advocacy networks reconstitute the identity of IFIs. This, it is argued, results from processes of socialization: social influence, persuasion and coercion by lobbying. A case study of the International Finance Corporation (IFC), as a member of the World Bank Group, is used to analyze how an IFI internalized sustainable development norms. The IFC finances private enterprise in developing countries by providing venture capital for private projects. Transnational advocacy networks socialized the IFC through influencing its projects, policies and institutions via direct and indirect interactions to the point where the organization now sees itself as a sustainable development financier. This article applies constructivist insights to the greening process in order to demonstrate how socialization can reshape an IFI's identity.
Hostage to Norms: States, Institutions and Global Forest Politics
Authors: Dimitrov Radoslav S.
Published: November 2005

Global forest politics reveal surprising impacts of environmental norms on state behavior at the international level. Negotiations regarding deforestation have repeatedly failed to produce a policy agreement. Instead of abandoning the deadlocked talks, governments created the United Nations Forum on Forests (UNFF), a hollow entity deliberately deprived of decision-making powers. Various theoretical perspectives fail to explain why states create blank international institutions without policy mandates. Several arguments are advanced here. First, a global norm of environmental multilateralism (NEM) helps explain the creation of the UNFF as well as universal state participation in it. Second, such “good” norms can have negative consequences in world politics. NEM prohibits states from disengaging from failed political initiatives, and fosters the creation of hollow institutions that nourish skepticism about the effectiveness of global governance. Finally, global forestry defies the widespread academic notion that norms, institutions and governance are coterminous. Sometimes states design “decoy” institutions whose function is to preempt governance.
Fishing under Flags of Convenience: Using Market Power to Increase Participation in International Regulation
Authors: DeSombre Elizabeth R.
Published: November 2005

Fishing that takes place on flag-of-convenience vessels, outside the international regulatory structure, is increasingly undermining the ability of fishery conservation organizations to manage fish stocks. Among the most affected are high seas and highly migratory stocks such as tuna, swordfish, and toothfish. The traditional approach to addressing this problem, efforts to persuade non-member flag states to join international agreements, has met with little success. Recently, efforts by regional fishery management organizations to allow, or require, member states to refuse to allow the importation or transshipment of fish products that cannot be shown to be caught under the rules of the organization, have had much more of an effect in reinforcing conservation efforts. In response to these measures, some flag states have joined international agreements and some have taken steps to stop fishing activity by ships in their registries. Even ships that do not comply with these rules may cease to find markets for their products. The case of fishing regulations suggests both that, in an era of globalization, individual actors are willing and able to avoid international rules, and that collective international action to exclude them from the benefits of doing so can improve global regulatory efforts.
Global Interdependent Ministry Partnerships in the Russian Context
Authors: Tiessen Douglas
Published: November 2005

In proposing "Global Interdependent Ministry Partnership," four elements in relation to the Russian context are identified: First, a description of the effects of globalization; Second, observations on how globalization has led to interdependent partnerships; Third, a theory of global interdependent ministry partnerships; and fourth, conclusions on the generalizability of this theory for the world in which we now live.Global interdependent ministry partnerships put the national church in the driver's seat. Too often the nationals of any given country are in the back seat from the outset, which leads to dependency and great difficulty in turning the wheel over to the national. With global interdependent ministry partnerships the national church calls the shots from the beginning; they choose to invite or not invite foreign missionaries to partner with them.
A New Christianity, But What Kind?
Authors: Phan Peter
Published: November 2005

The article examines Philip Jenkins's popular thesis that "Southern Christianity" represents a conservative return to a pre-Tridentine Christendom. While acknowledging the importance of Jenkins's emphasis on the demographic shift of the Christian population from the "North" to the "South" and its vast implications for the church's mission, the article argues that the form of Christianity that is taking place in the so-called Third World, at least in Asian Roman Catholicism, is anything but a return to the pre-Tridentine Christianity. The various phenomena that Jenkins notes such as healing, prophecy, popular piety, and a literalist reading of the Bible, should be viewed within the new context of the church's commitment to renewal and mission in terms of liberation, interculturation, and interreligious dialogue.
The Writings of William Carey: Journalism as Mission in a Modern Age
Authors: Alban Donald , Woods Robert , Daigle-Williamson Marsha
Published: November 2005

William Carey is reviewed as both product and producer of journalism, with an emphasis on the latter and its synergistic relationship to his mission work and the work of others. Carey's philosophy of life was formed largely by the written works of his predecessors and contemporaries. Specifically, Jonathan Edwards, John Bunyan, Jeremy Taylor, Captain James Cook, and Robert Hall, among others, clearly affected his outlook on theology, missions, Bible translation, ecumenism, and a host of related topics. Writings by Cook opened Carey's eyes to distant people, whom he evaluated in the light of his journalistically influenced theology. Consequently, Carey became concerned about the spiritual and moral state of the world abroad. His concern found expression in the Enquiry – a polemic for missionary work – and ultimately led him to Bengal, where his own attempts to influence people through journalism expanded.Carey's own writings and those of his colleagues at the Serampore Mission are the most obvious examples of his journalistic works. But they hardly stand alone. Thus, after the authors describe the emergence and significance of the Enquiry and the Serampore Press, they refer to other publications printed either at Serampore or elsewhere in response to the press' influence. Among these are works as diverse as textbooks, governmental publications, and periodical apologetics for Hinduism. The Serampore mission's expansion of Indian literacy also is reviewed because of its relevance to understanding the influence of others' writings on his life's philosophy and work. It further helps to shed light on Carey's distinct approach to evangelization, presented herein as a form of inculturation. Lastly, many would not have become readers of the mission's works had it not equipped them to read through its network of native schools. The authors suggest that Serampore's journalistic mission extended beyond the mere production of writings; it also included the production of a readership.
The Catholic Imagination and Popular Religion in Lowland Philippines: Missiological Significance of David Tracy's Theory of Religious Imaginations
Authors: Gener Timoteo
Published: November 2005

By way of critical appreciation, the author (an evangelical) investigates David Tracy's analysis of the Catholic imagination in relation to popular religiosity and inculturation in lowland Philippines. A survey of contemporary Evangelical and Roman Catholic views on folk religiosity sets the stage for the study as a whole. To explain and highlight the missiological significance of Tracy's approach, this study makes use of contemporary religio-philosophical (hermeneutical) and missiological perspectives. Such perspectives open up the missiological usefulness of Tracy's socio-theological analysis of the Catholic imagination especially for religionists and missiologists. They also point to the naturalistic limitations of Tracy's revisionist understanding of religion even as it encounters a non-Western religious outlook such as in the Philippines. A conversation with Tracy's approach becomes an instance of dialogue between Roman Catholics and Evangelicals not only on folk Catholicism, but also on revelation, inculturation and mission.
Peace Facilitation by Small States
Authors: Moolakkattu John Stephen
Published: November 2005

It is now four years since Norway formally embarked on the difficult task of facilitating negotiations in the protracted ethnic conflict in Sri Lanka. With an international record in peace-making and development assistance, Norway entered the fray with unmatched legitimacy. Unlike Norway's previous efforts aimed at brokering peace, the Sri Lankan facilitation was undertaken by assigning a conspicuous role to key governmental functionaries, and was less secretive in nature. Although a ceasefire has been signed and six rounds of talks between the government and the Tamil Tigers have been held, Norway's third-party role has been criticized by nationalists for being partial towards the Tigers, and by a section of peace activists for focusing on a minimalist agenda of peace. In this article, I examine the qualifications and motivations of Norway as a facilitator and also the different perceptions that the key stakeholders have about its third-party role. Furthermore, I assess the nature of the Norwegian efforts so far and the hurdles ahead for taking the peace process forward.