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Purpose: Osteoarthritis (OA) has been shown to be associated with decreased physical function, which may impact upon a person's self-rated health (SRH). Only a few studies have examined the association between OA and SRH in the general population, but to date none have used a clinical definition of OA. The objectives are: (1) To examine the cross-sectional association between clinical OA and fair-to-poor SRH in the general population; (2) To examine whether this association differs between countries; (3) To examine whether physical function is a mediator in the association between clinical OA and SRH., Methods: Baseline data of the European Project on OSteoArthritis (EPOSA) were used, which includes pre-harmonized data from six European cohort studies (n = 2709). Clinical OA was defined according to the American College of Rheumatology criteria. SRH was assessed using one question: How is your health in general? Physical function was assessed using the Western Ontario and McMaster Universities OA Index and Australian/Canadian OA Hand Index., Results: The prevalence of fair-to-poor SRH ranged from 19.8 % in the United Kingdom to 63.5 % in Italy. Although country differences in the strength of the associations were observed, clinical OA of the hip, knee and hand were significantly associated with fair-to-poor SRH in five out of six European countries. In most countries and at most sites, the association between clinical OA and fair-to-poor SRH was partly or fully mediated by physical function., Conclusions: Clinical OA at different sites was related to fair-to-poor SRH in the general population. Most associations were (partly) mediated by physical functioning, indicating that deteriorating physical function in patients with OA should be a point of attention in patient care.

Objective: To evaluate the role of comorbidity and pain in the association between hip/knee osteoarthritis (OA) with self-reported as well as performance-based functional limitations in a general elderly population., Methods: We analyzed the data of 2,942 individuals, ages between 65 and 85 years, who participated in the European Project on Osteoarthritis, which was made up of 6 European cohorts (from Germany, Italy, The Netherlands, Spain, Sweden, and the UK). Outcomes included self-reported physical function measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the participants' performance-based physical function was evaluated using the walking test., Results: While comorbidity did not affect the significant association between hip/knee OA and physical function limitations found in the participants, pain reduced the effect of OA on self-reported physical function, and it cancelled the effect of OA on the walking test. Obesity, anxiety, depression, and cardiovascular diseases were associated with the worst WOMAC scores. Obesity, cognitive impairment, depression, peripheral artery disease, and stroke were associated with the worst walking times., Conclusion: These findings demonstrate that while comorbidity is strongly and independently associated with functional limitations, it does not affect the OA-physical function association. Hip/knee OA is associated with self-reported impairment in physical function, which was only partially mediated by pain. Its association with physical function, as evaluated by the walking test, was instead completely mediated by pain., (© 2016, American College of Rheumatology.)

Objective: To investigate patterns of physical activity in older adults with knee osteoarthritis (OA) compared to older adults without knee OA across 6 European countries. We expect country-specific differences in the physical activity levels between persons with knee OA compared to persons without knee OA. A varying degree of physical activity levels across countries would express a facilitating or impeding influence of the social, environmental, and other contextual factors on a physically active lifestyle., Methods: Baseline cross-sectional data from the European Project on Osteoarthritis were analyzed. In total, 2,551 participants from 6 European countries (Germany, Italy, The Netherlands, Spain, Sweden, and the UK) were included., Results: Participants with knee OA were less likely to follow physical activity recommendations and had poorer overall physical activity profiles than those without knee OA (mean 62.9 versus 81.5 minutes/day, respectively; P = 0.015). The magnitude of this difference varied across countries. Detailed analysis showed that low physical activity levels in persons with knee OA could be attributed to less everyday walking time (odds ratio 1.31, 95% confidence interval 1.07-1.62)., Conclusion: This study highlighted the fact that having knee OA is associated with a varying degree of physical activity patterns in different countries. This national variation implies that low levels of physical activity among persons with knee OA cannot be explained exclusively by individual or disease-specific factors, but that social, environmental, and other contextual factors should also be taken into account., (© 2016, American College of Rheumatology.)

This study examines the availability and use of neighborhood resources in relation to clinical lower limb osteoarthritis (LLOA) in older participants from six European countries. Of the 2757 participants (65-85 years), 22.7% had LLOA. Participants with LLOA made more use of places to sit (OR=2.50; CI: 1.36-4.60 in the UK), and less use of parks and walking areas (OR=0.30; CI: 0.12-0.75 in Sweden), compared to participants without LLOA, particularly in countries with high availability of resources. The results suggest that specific features of the environment impact the use of neighborhood resources by older adults with LLOA., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Older people spend much time participating in leisure activities, such as taking part in organized activities and going out, but the extent of participation may differ according to both individual and environmental resources available. Chronic health problems become more prevalent at higher ages and likely necessitate tapping different resources to maintain social participation. This paper compares predictors of participation in social leisure activities between older people with and those without multimorbidity. The European Project on Osteoarthritis (EPOSA) was conducted in Germany, UK, Italy, The Netherlands, Spain and Sweden ( N  = 2942, mean age 74.2 (5.2)). Multivariate regression was used to predict social leisure participation and degree of participation in people with and without multimorbidity. Fewer older people with multimorbidity participated in social leisure activities (90.6 %), compared to those without multimorbidity (93.9 %). The frequency of participation was also lower compared to people without multimorbidity. Higher socioeconomic status, widowhood, a larger network of friends, volunteering, transportation possibilities and having fewer depressive symptoms were important for (the degree of) social leisure participation. Statistically significant differences between the multimorbidity groups were observed for volunteering and driving a car, which were more important predictors of participation in those with multimorbidity. In contrast, self-reported income appeared more important for those without multimorbidity, compared to those who had multimorbidity. Policies focusing on social (network of friends), physical (physical performance) and psychological factors (depressive symptoms) and on transportation possibilities are recommended to enable all older people to participate in social leisure activities.

Background: Osteoarthritis (OA) is the most common cause of disability in the elderly. Clinical frailty is associated with high mortality, but few studies have explored the relationship between OA and frailty. The objective of this study was to consider the association between OA and frailty/pre-frailty in an elderly population comprised of six European cohorts participating in the EPOSA project., Methods: Longitudinal study using baseline data and first follow-up waves, from EPOSA; 2,455 individuals aged 65-85 years were recruited from pre-existing population-based cohorts in Germany, Italy, the Netherlands, Spain, Sweden and the United Kingdom. Data were collected on clinical OA at any site (hand, knee or hip), based on the clinical classification criteria developed by the American College of Rheumatology (ACR). Frailty was defined according to Fried's criteria. The covariates considered were age, gender, educational level, obesity and country. We used multinomial logistic regression to analyse the associations between OA, frailty/pre-frailty and other covariates., Results: The overall prevalence of clinical OA at any site was 30.4 % (95 % CI:28.6-32.2); frailty was present in 10.2 % (95 % CI:9.0-11.4) and pre-frailty in 51.0 % (95 % CI:49.0-53.0). The odds of frailty was 2.96 (95 % CI:2.11-4.16) and pre-frailty 1.54 (95 % CI:1.24-1.91) as high among OA individuals than those without OA. The association remained when Knee OA, hip OA or hand OA were considered separately, and was stronger in those with increasing number of joints., Conclusions: Clinical OA is associated with frailty and pre-frailty in older adults in European countries. This association might be considered when designing appropriate intervention strategies for OA management.

A large number of calmodulin-like (CML) proteins are present in plants, but there is little detailed information on the functions of these proteins in rice (Oryza sativa L.). Here, the CML3 protein from rice (OsCML3) and its truncated form lacking the C-terminal extension (OsCML3m) were found to exhibit a Ca2+-binding property and subsequent conformational change, but the ability to bind the CaM kinase II peptide was only observed for OsCML3m. Changes in their secondary structure upon Ca2+-binding measured by circular dichroism revealed that OsCML3m had a higher helical content than OsCML3. Moreover, OsCML3 was mainly localized in the plasma membrane, whereas OsCML3m was found in the nucleus. The rice high mobility group B1 (OsHMGB1) protein was identified as one of the putative OsCML3 target proteins. Bimolecular fluorescence complementation analysis revealed that OsHMGB1 bound OsCML3, OsCML3m or OsCML3s (cysteine to serine mutation at the prenylation site) in the nucleus presumably through the methionine and phenylalanine-rich hydrophobic patches, confirming that OsHMGB1 is a target protein in planta. The effect of OsCML3 or OsCML3m on the DNA-binding ability of OsHMGB1 was measured using an electrophoretic mobility shift assay. OsCML3m decreased the level of OsHMGB1 binding to pUC19 double-stranded DNA whereas OsCML3 did not. Taken together, OsCML3 probably provides a mechanism for manipulating the DNA-binding ability of OsHMGB1 in the nucleus and its C-terminal extension provides an intracellular Ca2+ regulatory switch., (© The Author 2015. Published by ABBS Editorial Office in association with Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences.)

Objective: This study examined whether daily weather conditions, 3-day average weather conditions, and changes in weather conditions influence joint pain in older people with osteoarthritis (OA) in 6 European countries., Methods: Data from the population-based European Project on OSteoArthritis were used. The American College of Rheumatology classification criteria were used to diagnose OA in older people (65-85 yrs). After the baseline interview, at 6 months, and after the 12-18 months followup interview, joint pain was assessed using 2-week pain calendars. Daily values for temperature, precipitation, atmospheric pressure, relative humidity, and wind speed were obtained from local weather stations. Multilevel regression modelling was used to examine the pain-weather associations, adjusted for several confounders., Results: The study included 810 participants with OA in the knee, hand, and/or hip. After adjustment, there were significant associations of joint pain with daily average humidity (B = 0.004, p < 0.01) and 3-day average humidity (B = 0.004, p = 0.01). A significant interaction effect was found between daily average humidity and temperature on joint pain. The effect of humidity on pain was stronger in relatively cold weather conditions. Changes in weather variables between 2 consecutive days were not significantly associated with reported joint pain., Conclusion: The associations between pain and daily average weather conditions suggest that a causal relationship exist between joint pain and weather variables, but the associations between day-to-day weather changes and pain do not confirm causation. Knowledge about the relationship between joint pain in OA and weather may help individuals with OA, physicians, and therapists to better understand and manage fluctuations in pain.

This study aimed to explore the loneliness of several groups of older immigrants in Canada compared to native-born older adults. Data from the Canadian General Social Survey, Cycle 22 (N older adults = 3,692) were used. The dependent variable is the 6 item De Jong Gierveld loneliness scale. Determinants of loneliness included country of birth, ethnic background (cultural context); belongingness (community context) and social networks (social context). Results showed that only some immigrant groups are significantly lonelier than older adults born in Canada. Immigrants with similar language and culture are not lonelier; while those from countries that differ in native language/culture are significantly higher on loneliness. Multivariate analyses showed the importance of cultural background, of composition of the network of relatives and friends, and of local participation and feelings of belonging to the Canadian society in explaining loneliness of older immigrants.

Objective: Epidemiological studies of knee osteoarthritis (OA) have often used a radiographic definition. However, the clinical syndrome of OA is influenced by a broad range of factors in addition to the structural changes required for radiographic OA. Hence more recently several studies have adopted a clinical or self-reported approach to OA diagnosis rather than a radiographic approach. The aim of this study was to investigate agreement between radiographic OA and the clinical and self-reported diagnoses of OA., Design: Data were available for 199 men and 196 women in the Hertfordshire Cohort Study (HCS), UK. Participants completed a questionnaire detailing self-reported OA. Clinical OA was defined based on American College of Rheumatology (ACR) criteria. Knee radiographs were taken and graded for overall Kellgren and Lawrence (K&L) score., Results: The mean (standard deviation (SD)) age of study participants was 75.2 (2.6) years and almost identical proportions of men and women. The prevalence of knee OA differed depending on the method employed for diagnosis; 21% of the study participants self-reported knee OA, 18% of the participants had clinical knee OA and 42% of the participants had radiographic OA. Of those 72 study participants with a self-reported diagnosis of knee OA 52 (72%) had a radiographic diagnosis of knee OA, while 66% (39 out of 59) of study participants with clinical knee OA had a diagnosis of radiographic knee OA. However 58% of those participants diagnosed with radiographic OA did not have either self-reported knee OA or a diagnosis of clinical OA. Therefore in comparison with the radiographic definition of OA, both the clinical and self-report definitions had high specificity (91.5% & 91.5% respectively) and low sensitivity (24.5% and 32.7% respectively)., Conclusion: There is modest agreement between the radiographic, clinical and self-report methods of diagnosis of knee OA.

On August 8 2014, the World Health Organization (WHO) declared the outbreak of Ebola Virus Disease (EVD) evolving in West Africa since December 2013, a Public Health Emergency of International Concern (PHEIC). It is expected that the outbreak of Ebolavirus Disease (EVD) in West Africa will lead to increased testing of individuals in Europe for EVD. The severity of the situation in West Africa warranted a critical appraisal of the laboratory preparedness and response for EVD, with a focus on information needs for laboratories involved in diagnostics of rare viral diseases associated with the European Network for the Diagnostics of "Imported" Viral Diseases", ENIVD. Essential knowledge and knowledge gaps for an adequate laboratory response focusing on virus properties, infection kinetics, tests specifics and field performances were identified. An inventory of the laboratory capacity for EVD diagnostics among ENIVD laboratories was made.

While older people live in developing countries, little is known about the relative importance of features of their communities in influencing their liveability. We examine components of home and neighbourhood among older South Africans. Linear regression analyses revealed that features of home (basic amenities, household composition, financial status and safety) and neighbourhood (ability to shop for groceries, participate in organizations and feel safe from crime) are significantly associated with life satisfaction. Approaches to liveability that are person-centred and also set within contexts beyond home and neighbourhood are needed to address boundaries between home and neighbourhood; incorporate personal resources into liveability models and import broader environmental contexts such as health and social policy.

Background: As the prevalence of chronic disease amongst older workers is high and increasing, it is important to know if the large subgroup of older workers with chronic disease has specific needs when it comes to prolonging participation in paid work., Objectives: To investigate differences and similarities in predictors of having paid work in workers aged 55+ with and without chronic disease., Methods: Workers aged 55-62 years were selected from the 2002-2003 cohort of the Longitudinal Aging Study Amsterdam (n = 333). Potential predictors were: health, personality, work characteristics, and demographics. Per potential predictor, a logistic regression coefficient for 'having paid work in 2005-2006' was calculated for workers with and without chronic disease. A pooled estimate was computed and differences between the pooled estimate and the coefficients were tested. Results Follow-up data were available for 95 %, of whom 67 % still had paid work. Predictors of having paid work were similar for workers with and without chronic diseases, except for physical workload (χ(2) = 5.37; DF = 1) and psychosocial resources at work (χ(2) = 5.94; DF = 1). Having more psychosocial resources (OR = 3.57; 95 %CI 1.33-10.0) was predictive for having paid work in workers with chronic disease and not in workers without chronic disease. Lower age, more weekly working hours, no functional limitations, fewer depressive symptoms, lower neuroticism scores, and more sense of mastery were significantly associated with having paid work in all workers., Conclusions: Differences between predictors of having paid work between workers with and without chronic disease should be taken into account when aiming to prevent exit from the workforce. In particular the vulnerable subgroup of older workers with chronic disease and low psychosocial resources at work is more likely to quit working.

Background: In recent years chronic hepatitis E virus (HEV) infections have been reported in immunosuppressed patients, including HIV-positive patients with low CD4 cell counts. Because of delayed anti-HEV seroconversion in patients with CD4 cell count<200 cells/ml it is difficult to draw firm conclusions on HEV-seroprevalence in a population of HIV positive patients., Objectives: To determine the HEV seroprevalence in a population of HIV infected patients., Study Design: We retrospectively analysed the HEV prevalence in a population of 256 HIV infected patients with liver enzyme elevations (LEEs), using HEV specific antibody testing and HEV-RNA detection., Results: Within this cohort we observed a HEV-seroprevalence of 11.7%, without any anti-HEV IgM positive or HEV-RNA positive cases. HEV seropositivity was equally prevalent among different CD4(+) cell count groups., Conclusion: Although HIV infected patients in the Netherlands are at risk of acquiring HEV, the number of acute infections is low and no chronic cases were found., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Antibodies to Middle East respiratory syndrome coronavirus (MERS-CoV) were detected in serum and milk collected according to local customs from 33 camels in Qatar, April 2014. At one location, evidence for active virus shedding in nasal secretions and/or faeces was observed for 7/12 camels; viral RNA was detected in milk of five of these seven camels. The presence of MERS-CoV RNA in milk of camels actively shedding the virus warrants measures to prevent putative food-borne transmission of MERS-CoV.

Background: People with osteoarthritis (OA) frequently report that their joint pain is influenced by weather conditions. This study aimed to examine whether there are differences in perceived joint pain between older people with OA who reported to be weather-sensitive versus those who did not in six European countries with different climates and to identify characteristics of older persons with OA that are most predictive of perceived weather sensitivity., Methods: Baseline data from the European Project on OSteoArthritis (EPOSA) were used. ACR classification criteria were used to determine OA. Participants with OA were asked about their perception of weather as influencing their pain. Using a two-week follow-up pain calendar, average self-reported joint pain was assessed (range: 0 (no pain)-10 (greatest pain intensity)). Linear regression analyses, logistic regression analyses and an independent t-test were used. Analyses were adjusted for several confounders., Results: The majority of participants with OA (67.2%) perceived the weather as affecting their pain. Weather-sensitive participants reported more pain than non-weather-sensitive participants (M = 4.1, SD = 2.4 versus M = 3.1, SD = 2.4; p < 0.001). After adjusting for several confounding factors, the association between self-perceived weather sensitivity and joint pain remained present (B = 0.37, p = 0.03). Logistic regression analyses revealed that women and more anxious people were more likely to report weather sensitivity. Older people with OA from Southern Europe were more likely to indicate themselves as weather-sensitive persons than those from Northern Europe., Conclusions: Weather (in)stability may have a greater impact on joint structures and pain perception in people from Southern Europe. The results emphasize the importance of considering weather sensitivity in daily life of older people with OA and may help to identify weather-sensitive older people with OA.

Objectives: A general population job-exposure matrix (GPJEM) including physical and psychosocial demands as well as psychosocial resources applicable to older and retired workers was developed. Its validity was evaluated by examining associations of physical demands and iso-strain (combination of high psychosocial demands and low resources) with health., Methods: Physical and psychosocial work exposures reported by 55-64 year olds were derived from the Netherlands Working Conditions Survey and linked to the Netherlands Standard Classification of Occupations 1992. A GPJEM with low, moderate, and high probability of exposure to demands and resources was developed. To examine associations with health, two groups of the Longitudinal Aging Study Amsterdam were selected: current (i.e. at the time of the interview, 55-64 years) and former workers (55-84 years). Linear and logistic regression models were applied., Results: Use of force and work in uncomfortable positions were significantly associated with functional limitations and self-perceived health (SPH), but not hip or knee osteoarthritis (OA), in current and former workers. A moderate probability of repetitive movements was associated with functional limitations in former workers. A high probability of repetitive movements was associated with functional limitations in current and former workers as well as with SPH and hip and knee OA in former workers. Respondents formerly exposed to iso-strain had significantly higher diastolic blood pressure and more often hypertension. No such associations were found in current workers. No association was found with cardiovascular disease., Conclusions: The results suggest that our GPJEM accurately classifies jobs according to physical demands and, although less clearly, iso-strain.

Treatment of cytomegalovirus (CMV) disease in transplant patients is challenging and, with antiviral resistance to first-line drugs, it remains uncertain which treatment algorithm to follow. Some data suggest that leflunomide, a pyrimidine synthesis inhibitor, can be used to treat resistant CMV infections. We report a 57-year-old CMV immunoglobulin-G (IgG)-seronegative woman, who received a bilateral lung transplant (LuTx) from a CMV IgG-positive donor with CMV primary disease. The CMV strain was genotypically resistant to ganciclovir, foscarnet, and cidofovir. After starting leflunomide as add-on therapy to a multidrug anti-CMV regimen, viral load declined substantially in 2 months without adverse events. This experience is discussed against the background of existing literature on the use of leflunomide as an anti-CMV agent in LuTx recipients., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Stress is associated with an increased incidence of cardiovascular disease. The impact of chronic stress on cardiovascular risk has been studied by measuring cortisol in serum and saliva, which are measurements of only 1 time point. These studies yielded inconclusive results. The measurement of cortisol in scalp hair is a novel method that provides the opportunity to measure long-term cortisol exposure. Our aim was to study whether long-term cortisol levels, measured in scalp hair, are associated with cardiovascular diseases., Methods: A group of 283 community-dwelling elderly participants were randomly selected from a large population-based cohort study (median age, 75 y; range, 65-85 y). Cortisol was measured in 3-cm hair segments, corresponding roughly with a period of 3 months. Self-reported data concerning coronary heart disease, stroke, peripheral arterial disease, diabetes mellitus, and other chronic noncardiovascular diseases were collected., Results: Hair cortisol levels were significantly lower in women than in men (21.0 vs 26.3 pg/mg hair; P < .001). High hair cortisol levels were associated with an increased cardiovascular risk (odds ratio, 2.7; P = .01) and an increased risk of type 2 diabetes mellitus (odds ratio, 3.2; P = .04). There were no associations between hair cortisol levels and noncardiovascular diseases., Conclusions: Elevated long-term cortisol levels are associated with a history of cardiovascular disease. The increased cardiovascular risk we found is equivalent to the effect of traditional cardiovascular risk factors, suggesting that long-term elevated cortisol may be an important cardiovascular risk factor.

Background: Osteoarthritis (OA), the most common form of arthritis, is a major contributor to functional impairment and loss of independence in older persons. The European Project on OSteoArthritis (EPOSA) is a collaborative study involving six European cohort studies on ageing. This project focuses on the personal and societal burden and its determinants of osteoarthritis. This paper describes the design of the project, and presents some descriptive analyses on selected variables across countries., Methods/design: EPOSA is an observational study including pre-harmonized data from European cohort studies (Germany, Italy, the Netherlands, Spain, Sweden and the United Kingdom) on older community-dwelling persons aged 65 to 85 years. In total, 2942 persons were included in the baseline study with a mean age of 74.2 years (SD 5.1), just over half were women (51,9%). The baseline assessment was conducted by a face-to-face interview followed by a clinical examination. Measures included physical, cognitive, psychological and social functioning, lifestyle behaviour, physical environment, wellbeing and care utilisation. The clinical examination included anthropometry, muscle strength, physical performance and OA exam. A follow-up assessment was performed 12-18 months after baseline., Discussion: The EPOSA study is the first population-based study including a clinical examination of OA, using pre-harmonized data across European countries. The EPOSA study provides a unique opportunity to study the determinants and consequences of OA in general populations of older persons, including both care-seeking and non care-seeking persons.

Background: In plants, a large family of calmodulin (CaM) and CaM-like (CML) proteins transduce the increase in cytosolic Ca2+ concentrations by binding to and altering the activities of target proteins, and thereby affecting the physiological responses to a vast array of stimuli. Here, transcript expression analysis of Cam and CML gene family members in rice (Oryza sativa L.) was extensively examined., Results: Cam and CML genes in rice exhibited differential expression patterns in tissues/organs. Under osmotic stress and salt stress, expression of OsCam1-1, OsCML4, 5, 8, and 11 was induced with different kinetics and magnitude. OsCML4 and 8 mRNA levels significantly increased by 3 h after treatment and remained elevated for at least 24 h while expression of OsCam1-1, OsCML5 and 11 was up-regulated as early as 1-3 h before rapidly returning to normal levels. Several cis-acting elements in response to abiotic stresses, including DREs (important promoter elements responsive to drought, high salt, and cold stress), were detected in the 5' upstream regions of these genes. The observed induction of the GUS activity of transgenic rice plants via the OsCam1-1 promoter appeared to be biphasic and dependent on the severity of salt stress., Conclusions: Large OsCam and OsCML gene family members likely play differential roles as signal transducers in regulating various developmental processes and represent important nodes in the signal transduction and transcriptional regulation networks in abiotic stresss responses mediated by the complex Ca2+ signals in plants, which are rich in both spatial and temporal information.

Endothelial progenitor cells (EPC) play a central role in endothelial maintenance and repair. Endothelial colony-forming cells (ECFC) form a subpopulation of EPC. ECFC are readily attainable, can be easily isolated, possess a high proliferation potential, and are therefore a promising source of endothelial cells (EC) for future cardiovascular therapeutic applications. The extent to which these cells respond to shear stress as adult vascular EC remains to be elucidated. Here, we study the transcriptional response of ECFC induced by shear stress and compare it with the response of mature arterial and venous cells. ECFC, as well as human umbilical vein EC (HUVEC) and human umbilical artery EC (HUAEC), were subjected to low (0.5 Pa) and high (2.5 Pa) shear stress. The endothelial differentiation phenotype and transcriptional responses were analyzed using immunocytochemistry and quantitative polymerase chain reaction (Q-PCR). Performing absolute quantification of copy numbers by Q-PCR allows comparing the responses of cell types relative to each other. Our data show that isolated ECFC resemble mature EC in cobblestone morphology and endothelial marker expression. Absolute Q-PCR quantification revealed that although being truly endothelial, ECFC do not fully resemble HUVEC or HUAEC in the expression of specific differentiation markers. When subjected to shear stress, ECFC show a mature response to fluid flow, comparable to that of HUVEC and HUAEC. The capacity of endothelial progenitors to respond to fluid flow in a similar manner to HUVEC and HUAEC highlights the universal response of EC to fluid shear stress, independently of their endothelial differentiation status. This property supports the use of these cells as an EC source for tissue engineering applications.

Endothelial cells (EC) translate biomechanical forces into functional and phenotypic responses that play important roles in cardiac development. Specifically, EC in areas of high shear stress, i.e., in the cardiac outflow tract and atrioventricular canal, are characterized by high expression of Krüppel-like factor 2 (Klf2) and by transforming growth factor-beta (Tgfβ)-driven endothelial-to-mesenchymal transition. Extraembryonic venous obstruction (venous clip model) results in congenital heart malformations, and venous clip-induced alterations in shear stress-related gene expression are suggestive for an increase in cardiac shear stress. Here, we study the effects of shear stress on Klf2 expression and Tgfβ-associated signaling in embryonic EC in vivo using the venous clip model and in vitro by subjecting cultured EC to fluid flow. Cellular responses were assessed by analysis of Klf2, Tgfβ ligands, and their downstream signaling targets. Results show that, in embryonic EC, shear stress activates Tgfβ/Alk5 signaling and that induction of Klf2 is an Alk5 dependent process., (Copyright © 2011 Wiley-Liss, Inc.)

We investigated whether a depth aftereffect is better explained in a surface-based organization of depth representation (Nakayama & Shimojo, 1992), where depth is represented in conjunction with surface features, rather than a coordinate-based organization, where depth is represented in conjunction with spatial position. Observers adapted to a stereogram depicting a surface with reference plane and were tested with a surface with either the same contour or position as the adaptation surface. The aftereffect did not depend on test surface position or contour. Thus, a depth aftereffect can be caused by a mechanism that does not depend on grouping by surface contour or position., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Despite FDA approval and CE marking of commercial tests, manufacturer-independent testing of the technical aspects of newly developed tests is important. To evaluate the analytical performance and explore the clinical applicability of the new Roche COBAS AmpliPrep COBAS TaqMan HIV-1 test, version 2.0 (CAP/CTM v2.0), platform comparison was performed with the Roche CAP/CTM test, version 2.0, the COBAS Amplicor HIV-1 Monitor Test, version 1.5 (CAP/CA v1.5), the COBAS AmpliPrep COBAS TaqMan HIV-1 Test (CAP/CTM v1.0), and the Abbott m2000 RealTime HIV-1 assay on panels and diagnostic samples. Specificity was tested for HIV-2 samples. Furthermore, samples from HIV-1-seropositive individuals with CAP/CA v1.5-measured viral loads below 50 HIV-1 RNA copies per ml (cp/ml) and replicates of HIV-1-seronegative plasma were tested in a checkerboard analysis. CAP/CTM v2.0 is HIV-1 specific, with broad genotype inclusivity and no serious underquantification of viral load relative to the other assays used. Low viral loads below the threshold of quantification for CAP/CA v1.5 are observed with CAP/CTM v2.0. A CAP/CTM v2.0-measured viral load of >50 copies/ml in these samples correlated with therapy failure. In conclusion, CAP/CTM v2.0 is an accurate and reliable test for HIV-1 viral load measurement relative to the other assays used with respect to specificity, sensitivity, and genotype inclusivity.

Objectives: This article examines the effect that family structure has on the contact between older adults and their (step)children. A comparison is made among 3 family structures: biological families, complex stepfamilies, and simple stepfamilies., Methods: The sample consists of respondents aged 55 years or older from the "Living Arrangements and Social Networks of Older Adults in the Netherlands" survey of 1992. The contact between biological relationships and steprelationships is measured by means of 2 items: contact frequency and whether contact is perceived as regular and important., Results: Parents have less contact with their biological children in stepfamilies compared with parents with their children in biological families. The contact with biological children is perceived as more often regular and important in biological families and complex stepfamilies compared with simple stepfamilies. No difference was found in the contact between stepparents and stepchildren in simple and complex stepfamilies. However, the contact with stepchildren is perceived as more often regular and important in simple stepfamilies in comparison to complex stepfamilies., Discussion: It is not so much the difference between biological children and stepchildren that counts when studying the contact between (step)parents and (step)children, as what the structure of the aging (step)family is.

Patients with chronic hepatitis B (CHB) who will and those who will not respond to adefovir (ADV) monotherapy need to be identified at an early stage in order to adjust treatment and prevent future development of antiviral resistance. In a single-centre cohort study, we investigated 76 CHB patients [50% hepatitis B e antigen (HBeAg)-positive] treated with long-term ADV monotherapy. During a median follow-up of 122 (24-185) weeks, 42 (55%) patients achieved virologic response (VR), defined as HBV-DNA levels <10(3) copies/mL, and 10 patients (13%) developed genotypic ADV resistance. Independent baseline predictors of VR were HBeAg negativity [hazard ratio (HR) 2.98; 95% confidence interval (CI) 1.24-7.19; P = 0.02], high alanine aminotransferase (ALT) levels (HR 1.11; 95% CI 1.05-1.18; P = 0.001), and low HBV-DNA levels (HR 0.56; 95% CI 0.41-0.75; P < 0.001). HBV-DNA at week 24 demonstrated a higher predictive value for VR than HBV-DNA at week 48. Important predictors of genotypic resistance were presence of cirrhosis (HR 6.54; 95% CI 1.39-30.9; P = 0.018), and not achieving VR during treatment (HR 6.60; 95% CI 1.35-32.4; P = 0.008). Patients without VR at week 24 already demonstrated a trend towards the emergence of ADV resistance (P = 0.07). HBV-DNA at week 24 was a better on-treatment predictor of VR than HBV-DNA at week 48, and ADV-resistant mutations developed more frequently in patients without VR at week 24. Therefore, our study suggests that virologic response to ADV therapy can be assessed at 24 weeks, instead of the generally recommended 48 weeks.

Calmodulin (CaM) proteins, members of the EF-hand family of Ca(2+)- binding proteins, represent important relays in plant calcium signals. Here, OsCam1-1 was isolated by PCR amplification from the rice genome. The gene contains an ORF of 450 base pairs with a single intron at the same position found in other plant Cam genes. A promoter region with a TATA box at position-26 was predicted and fused to a gus reporter gene, and this construct was used to produce transgenic rice by Agrobacterium-mediated transformation. GUS activity was observed in all organs examined and throughout tissues in cross-sections, but activity was strongest in the vascular bundles of leaves and the vascular cylinders of roots. To examine the properties of OsCaM1-1, the encoding cDNA was expressed in Escherichia coli. The electrophoretic mobility shift when incubated with Ca(2+) indicates that recombinant OsCaM1-1 is a functional Ca(2+)-binding protein. In addition, OsCaM1-1 bound the CaMKII target peptide confirming its likely functionality as a calmodulin.

The aim of this study was to analyze the restriction fragment length polymorphism and direct sequencing results in genotyping of hepatitis B virus from a Turkish population in a clinical virology laboratory. Serum samples of 54 chronic hepatitis B patients attending the Ege University Hospital were studied. Sequences of partial S gene PCR products were analysed and RFLP was performed. Fifty-three isolates could be identified by direct sequencing as genotype D. One sample needed to be cloned and determined as genotype D. Forty-two isolates were genotyped as D with RFLP according to published determinative patterns. Twelve isolates had undefined patterns. Eight of them suggested a mixture of isolates with different patterns and cloning of these samples confirmed the presence of heterogeneous isolates. Four isolates with undefined pattern were determined as genotype D by direct sequencing. All the studied isolates were genotype D. The results of this studied population suggest that RFLP is suitable for HBV genotyping in a routine clinical virology laboratory setting. However sequence analysis and even cloning may be needed to clarify indeterminate results.

Primary cilia are mechanosensors for fluid shear stress, and are involved in a number of syndromes and congenital anomalies. We identified endothelial cilia in areas of low shear stress in the embryonic heart. The objective of the present study was to demonstrate the role of primary cilia in mechanosensing. Ciliated embryonic endothelial cells were cultured from the heart, and non-ciliated cells from the arteries. Non-ciliated cells that were subjected to fluid shear stress showed significantly less induction of the shear marker Krüppel-Like Factor-2, as compared to ciliated cells. In addition, ciliated cells from which the cilia were chemically removed show a similar decrease in flow response. This shows that primary cilia sensitize endothelial cells for fluid shear stress. In addition, we targeted and stabilized the connection of the cilium to the cytoplasm by treatment with Colchicine and Taxol/Paclitaxel, respectively, and show that microtubular integrity is essential to sense shear stress., ((c) 2008 Wiley-Liss, Inc.)

The level of apoptosis in rectal carcinomas of patients treated by surgery only predicts local failure; patients with intrinsically high-apoptotic tumors develop less local recurrences than patients with low levels of apoptosis. To identify genes involved in this intrinsic apoptotic process in vivo, 47 rectal tumors with known apoptotic phenotype (24 low- and 23 high-apoptotic) were analyzed by oligonucleotide microarray technology. We identified several genes differentially expressed between low- and high-apoptotic tumors. Unsupervised clustering of the tumors based on expression levels of these genes separated the low-apoptotic from the high-apoptotic tumors, indicating a gene expression-dependent regulation. In addition, this clustering revealed two subgroups of high-apoptotic tumors. One high-apoptotic subgroup showed subtle differences in mRNA and protein expression of the known apoptotic regulators BAX, cIAP2 and ARC compared to the low-apoptotic tumors. The other subgroup of high-apoptotic tumors showed high expression of immune-related genes; predominantly HLA class II and chemokines, but also HLA class I and interferon-inducible genes were highly expressed. Immunohistochemistry revealed HLA-DR expression in epithelial tumor cells in 70% of these high-apoptotic tumors. The expression data suggest that high levels of apoptosis in rectal carcinoma patients can be the result of either slightly altered expression of known pro- and anti-apoptotic genes or high expression of immune-related genes.

Purpose: The combination of radiotherapy and good quality surgery reduces local recurrence rate for rectal cancer patients. This study assesses the prognostic value of both intrinsic and radiotherapy-induced apoptosis and evaluates the relevance of radiotherapy for outcome of rectal cancer patients., Experimental Design: Tumor samples (1,198) were available from the Dutch Total Mesorectal Excision trial, in which rectal cancer patients were treated with standardized surgery and randomized for preoperative short-term radiotherapy or not. Tumor samples were obtained at time of surgery. Tissue microarrays were constructed and stained with the active caspase-specific M30 antibody to determine the amount of apoptotic epithelial tumor cells., Results: Nonirradiated patients with a negative circumferential margin displaying lower than median levels of apoptosis developed more local recurrences (10.5% versus 6.1%; P=0.06) and more rapidly after surgery than patients with high intrinsic apoptosis in their tumors (median time to recurrence, 13.0 versus 21.3 months; P=0.04). In multivariate analysis, intrinsic apoptosis was an independent predictor for the development of local recurrences (hazard ratio, 2.0; P=0.05). Radiotherapy increased apoptosis level (11 versus 23 apoptotic cells/mm2 tumor epithelium; P<0.001), but this apoptosis did not influence patients' prognosis., Conclusions: Rectal cancer patients with low intrinsic apoptosis will benefit from radiotherapy with respect to the development of local recurrences. Because apoptosis is an inherent characteristic of tumors, patients who do not need radiotherapy may be selected based on the apoptotic index of the primary tumor.

Characterization results of the hepatitis B virus (HBV) genome before, during and after antiviral treatment have changed in the last year for a number of reasons. First of all, with the introduction of more nucleoside and nucleotide antiviral therapies, it has become clear that variants or mutants do emerge in time. Viral genomic changes in the HBV polymerase gene can result in a direct antiviral effect, but compensatory mutations can also be identified during prolonged treatment periods. Furthermore, there is an increasing number of reports suggesting that HBV genotypes can be related to, for example, disease progression or the effect of antiviral treatment itself (alpha-interferon or lamivudine). Combined with HBV DNA viral load monitoring, an increase in viral load or a limited reduction during treatment is indicative of genomic changes related to resistance. However, these genomic changes can also be present in the absence of an increase in HBV DNA. Methodologies for the detection of these variants, as well as the determination of genotypes, are rather straightforward. Sequence analysis is time-consuming and expensive, but provides the most information, particularly if not all information on mutations related to antiviral resistance is known. However, the sensitivity of direct sequencing for the presence of minor variant populations is poor, and no mixtures of variant populations are, in general, detected. The ability to detect minor populations and, if possible, even quantify them, gives more insightful information on the dynamic evolution of the virus itself. Antiviral treatment can result in the appearance of more than one population of variants, which can be present for a prolonged period of time, and even remain undetected with current technologies. However, screening specifically for these variant populations before starting treatment for so-called untreated patients (who have received no antiviral treatment for, e.g., 6 months) has already shown that the effects of treatment can be biased. Furthermore, the detection of more dynamic viral populations - including both wild-type and resistant variants - during, but also after therapy, does provide helpful information in the analysis of virological data. Technologies enabling the detection and quantification of these variant populations are presented and discussed.

Background: The molecular determinants of carcinogenesis, tumor progression and patient prognosis can be deduced from simultaneous comparison of thousands of genes by microarray analysis. However, the presence of stroma cells in surgically excised carcinoma tissues might obscure the tumor cell-specific gene expression profiles of these samples. To circumvent this complication, laser microdissection can be performed to separate tumor epithelium from the surrounding stroma and healthy tissue. In this report, we compared RNAs isolated from macrodissected, of which only surrounding healthy tissue had been removed, and microdissected rectal carcinoma samples by microarray analysis in order to determine the most reliable approach to detect the expression of tumor cell-derived genes by microarray analysis., Results: As microdissection yielded low tissue and RNA quantities, extra rounds of mRNA amplification were necessary to obtain sufficient RNA for microarray experiments. These second rounds of amplification influenced the gene expression profiles. Moreover, the presence of stroma cells in macrodissected samples had a minor contribution to the tumor cell gene expression profiles, which can be explained by the observation that more RNA is extracted from tumor epithelial cells than from stroma., Conclusion: These data demonstrate that the more convenient procedure of macrodissection can be adequately used and yields reliable data regarding the identification of tumor cell-specific gene expression profiles.

Ca(2+)/calmodulin transduction pathways have been implicated in mediating stress response and tolerance in plants. Here, three genes encoding calmodulin (Cam) members of the EF-hand family of Ca(2+)-binding proteins were identified from Oryza sativa L. databases. Complementary DNA for each of the calmodulin genes, OsCam1, OsCam2, and OsCam3 were sequenced. OsCam1 and OsCam2 encode a conventional 148-amino acid calmodulin protein that contains four characteristic Ca(2+)-binding motifs. OsCam3 encode a similar protein with a 38-amino-acid extension containing a putative prenylation site (CVIL) at the carboxyl terminus. RT-PCR showed that each of the genes is expressed in leaves and roots of 2-week old rice seedlings. By RNA gel blot analysis, OsCam1 mRNA levels strongly increased in response to NaCl, mannitol and wounding treatments. In contrast, OsCam2 mRNA levels were relatively unchanged under all conditions investigated. NaCl treatment and wounding also increased the OsCam3 mRNA level, but in a more transient manner. Our results indicate that although the expression of genes encoding different calmodulin isoforms is ubiquitous, they are differentially regulated by various stress signals. In addition, we have demonstrated that the calcium-channel blocker lanthanum chloride inhibited the induction of OsCam1 gene expression by both NaCl and mannitol treatments. These results suggest that osmotic stressinduced expression of OsCam1 gene requires the [Ca(2+)]cyt elevation that is known to occur in response to these stimuli.

There are different methods and systems for quantification of HBV-DNA in clinical virology laboratories. The aim of this study was to evaluate the agreement of the polymerase chain reaction (PCR) protocol with ABI Prism 7000 instrument (PE Biosystems) which was designed and optimised for ABI Prism 7700 (PE Biosystems). Serum samples obtained from 168 chronic hepatitis B patients were treated with "High Pure Viral Nucleic Acid Kit" (Roche Applied Science, USA), and MagnaPure LC isolation station (Roche Applied Science, Germany) was used for HBV-DNA isolation. Real time PCR procedure which amplifies pre-S gene of HBV genome was performed. Amplification and detection steps of all samples were performed with ABI Prism 7700 and 7000 Sequence Detection Systems. Among 168 samples, results of 124 serum samples were found to be in dynamic ranges of the tests. The results of these 124 samples obtained from ABI 7000 and ABI 7700 were concordant. Among the rest of 44 samples; one yielded higher than 10(10) copies/mL with two of the systems; six samples gave results higher than 10(10) copies/mL only with 7700; thirty samples were found negative with both of the systems; seven samples were positive (320-1220 copies/mL) with 7000 but negative with 7700. As a result this PCR protocol can be used in ABI 7000 system according to viral quality control (VQC) results. However, since the results of samples with HBV-DNA less than 1 x 10(6) copy/ml were discordant with the results obtained by ABI 7700 system, it can be concluded that different systems must not be used for the management and monitoring of the same patient.

Pathogens of the bacterial genus Bordetella cause respiratory disease in humans and animals. Although virulence and host specificity vary across the genus, the genetic determinants of this diversity remain unidentified. To identify genes that may underlie key phenotypic differences between these species and clarify their evolutionary relationships, we performed a comparative analysis of genome content in 42 Bordetella strains by hybridization of genomic DNA to a microarray representing the genomes of three Bordetella species and by subtractive hybridization. Here we show that B. pertussis and B. parapertussis are predominantly differentiated from B. bronchiseptica by large, species-specific regions of difference, many of which encode or direct synthesis of surface structures, including lipopolysaccharide O antigen, which may be important determinants of host specificity. The species also exhibit sequence diversity at a number of surface protein-encoding loci, including the fimbrial major subunit gene, fim2. Gene loss, rather than gene acquisition, accompanied by the proliferation of transposons, has played a fundamental role in the evolution of the pathogenic bordetellae and may represent a conserved evolutionary mechanism among other groups of microbial pathogens.

Using both traditional methods and broad-range 18S ribosomal DNA (rDNA) polymerase chain reaction, we examined 2 cases of lethal cestodiasis, in which the disease agent had been poorly identified or misidentified. In one case, involving a patient with AIDS, we identified the human dwarf tapeworm, Hymenolepis nana, as a cause of aberrant metastatic larval disease. In the second case with similar pathologic abnormalities, involving a patient with Hodgkin disease, we identified a larval cestode with a previously uncharacterized 18S rDNA sequence. A prior report of this case nearly 30 years ago, based on tissue examination, had suggested that the parasite was a sparganum.

A 3-D curvature contrast effect has been reported in shading-and-texture-defined (Curran & Johnson (1996). Vision Research 36, 3641-3653) and in stereoscopically defined (te Pas, Rogers, & Ledgeway (2000). Current Psychology Letters: Brain, Behaviour and Cognition 1, 117-126) stimuli. Our experiments show that a clear 3-D curvature contrast effect also occurs in motion-defined stimuli. The magnitude of the effect is similar in motion-, stereo- and shading-and-texture defined stimuli, suggesting that the 3-D curvature contrast effect is shape-based. We find a distinct contrast effect that is similar in the case of inducers that contain second-order (curvature) information and in the case of inducers that contain only first-order (slant and tilt) information. The effect with inducers that contain only zeroth-order (depth) information is very small. We conclude that the first-order structure is sufficient to induce a 3-D contrast effect.

Cyclospora cayetanensis is a coccidian parasite which causes severe gastroenteritis in humans. Molecular information on this newly emerging pathogen is scarce. Our objectives were to assess genetic variation within and between human-associated C. cayetanensis and baboon-associated Cyclospora papionis by examining the internal transcribed spacer (ITS) region of the ribosomal RNA operon, and to develop an efficient polymerase chain reaction- (PCR)-based method to distinguish C. cayetanensis from other closely related organisms. For these purposes, we studied C. cayetanensis ITS-1 nucleotide variability in 24 human faecal samples from five geographic locations and C. papionis ITS-1 variability in four baboon faecal samples from Tanzania. In addition, a continuous sequence encompassing ITS-1, 5.8S rDNA and ITS-2 was determined from two C. cayetanensis samples. The results indicate that C. cayetanensis and C. papionis have distinct ITS-1 sequences, but identical 5.8S rDNA sequences. ITS-1 is highly variable within and between samples, but variability does not correlate with geographic origin of the samples. Despite this variability, conserved species-specific ITS-1 sequences were identified and a single-round, C. cayetanensis-specific PCR-based assay with a sensitivity of one to ten oocysts was developed. This consistent and remarkable diversity among Cyclospora spp. ITS-1 sequences argues for polyparasitism and simultaneous transmission of multiple strains.

A highly reproducible and sensitive real-time detection assay based on TaqMan technology was developed for the detection of hepatitis B virus (HBV) DNA and compared with two commercially available assays. The assay was validated with the Viral Quality Control panel, which also includes EUROHEP HBV DNA standards. This real-time PCR detection system had a dynamic range of 373 to 10(10) genome copies per ml and showed an excellent correlation with both the commercial HBV Digene Hybrid Capture II microplate assay (Digene Diagnostics) and the HBV MONITOR assay (Roche Diagnostics). To demonstrate its clinical utility, four chronically HBV-infected patients treated with lamuvidine were monitored using the three different assays. From the results we concluded that this assay is an excellent alternative for monitoring of HBV-infected patients in routine diagnostics and clinical practice, enabling the analysis of a large dynamic range of HBV DNA in a single, undiluted sample.

Two DNA typing methods, probe-generated restriction fragment length polymorphism analysis and single-adapter amplified fragment length polymorphism analysis, were used to study the genetic relationships among 90 Moraxella catarrhalis strains. Both methods were found to be highly concordant, generating a dendrogram with 2 main branches. The division of the M. catarrhalis population into 2 subspecies was supported by analysis of the 16S rRNA sequences. Both beta-lactamase-positive and beta-lactamase-negative strains were found in all main branches, suggesting horizontal transfer of the beta-lactamase gene. In contrast, 2 virulence traits, complement resistance and adherence to epithelial cells, were strongly associated with 1 of the 2 subspecies. The branch depth suggested that complement-resistant adherent strains diverged from a common ancestor more recently than did complement-sensitive nonadherent strains. These findings suggest the existence of subpopulations of M. catarrhalis that differ in virulence, and they may have implications for vaccine development.

We investigated the extent to which the human visual system can detect discontinuities in first-order optical flow fields. We constructed two types of spatial discontinuities: a circular split field with a straight edge and a disk with annular surround. We used two different first-order optical flow components: an expansion and a rotation. We found an intriguing difference in the detection thresholds for straight and circular discontinuities. Whereas straight discontinuities yielded thresholds of 10%-50% difference in expansion or rotation, circular discontinuities could, at first, only be detected at extreme differences (>> 100%). After a learning period, thresholds for such stimuli decreased, but they remained significantly higher than thresholds for the straight edge. Thresholds rose for stimuli that formed a gradual transition between a circular and a straight edge, and they decreased with increasing eccentricity of the circular discontinuity. Results suggest that symmetry in this stimulus, defined by the coincidence of the center of expansion or rotation and the center of the circular discontinuity, was responsible for the difference in thresholds for circular and straight discontinuities.

We investigate how well the direction of the expansion gradient and the direction of a spatial step in expansion can be extracted from a complex optical flow field. The expansion gradient is an invariant of the second-order structure under rotations of the image plane. Our stimuli consist of sparse random dot patterns in a circular window with a diameter of 20 degrees. We find that translational velocity masks the direction of both the expansion gradient and the step in expansion. Thresholds for both the expansion gradient and the step in expansion are found to be similar for a wide range of expansions. We introduce two simple models that use the thresholds for the step in expansion to predict thresholds for the expansion gradient. Results of these models are comparable with the results of our subjects, showing that we do not need a hypothetical separate mechanism for the detection of second-order structure to explain the data.

Thresholds for the detection of rotation and divergence in the presence of a translational component in sparse random dot patterns are determined for human observers and two computer algorithms. The algorithms only make use of local velocity directions and not of local velocity magnitude (speed). The results show that psychophysical performance in this task can be well described without the need of specialized mechanisms tuned to either rotation or divergence. Possibly, integration of information over more than two frames occurs for low velocities. For high velocities the correspondence problem seems to limit performance.

Small optical flow fields are involved in object and shape recognition. These tasks depend on high resolution and low speed of the flow-field elements. Large optical flow fields are involved in tasks such as orientation and navigation, which require flow-field elements to move at high speed. From the above, we would expect to find different behavior of subjects for different parameter ranges of field size and speed of the elements. In this paper, we address the question of whether such different behavior exists for a task that is associated neither with object recognition nor with navigation. We obtained detection thresholds for expansion in the presence of translation for a wide range of field sizes. The same paradigm was used to investigate whether subjects made efficient use of peripheral information. We found viewing-distance invariance, meaning that subjects' performance scaled with stimulus size. Subjects performed very similarly with and without foveal information.

We measured psychophysical thresholds for the detection of four different optic flow components in the presence of a translational velocity. We also measured thresholds for detection of rotation in the presence of expansion and for expansion in the presence of rotation. Our stimuli consisted of sparse random dot patterns. Detection thresholds are similar for all four optic flow components. Thus, our experiments indicate that our subjects use a factor that is similar in all first-order flow components, namely the relative orientation of the velocity vectors. First-order components can be extracted independently of both each other and translational velocity.

Active haptic discrimination of mathematically well-defined surfaces was investigated. The quadric surfaces were defined in terms of 'shape index'--a quantity describing shape--and 'curvedness'--a quantity describing overall curvature. In these experiments shape index was varied and curvedness kept constant. The influence of laterality (unilateral versus bilateral discrimination) was tested in separate sessions. No influence of shape on the discrimination of solid objects was found. From the results an estimate can be made of the just-noticeable difference in terms of shape-index units. There was a significant effect of laterality on discrimination: performance with unilateral (successive) examination (both with left and with right hand) was better than with bilateral (simultaneous) examination.