Strain-specific immunomodulatory effects of Lactobacillus plantarum strains on birch-pollen-allergic subjects out of season.

BACKGROUND: Allergic diseases are increasing world-wide, and according to the hygiene hypothesis may be related to a decreased exposure to environmental bacteria. Probiotic bacteria are recognized for their immunomodulating properties, and may benefit allergy patients. In vitro studies reveal immunomodulatory effects that are strain dependent. Differential immunomodulatory in vitro capacities cannot be extrapolated directly to in vivo efficacy. Thus, in vitro screening should preferably be followed by a comparative analysis of the selected immunomodulatory strains in an in vivo setting. OBJECTIVE: We selected five Lactobacillus strains on their IL-10-inducing capacity, and evaluated the immunomodulatory properties in birch-pollen-allergic subjects outside the hayfever season, with a reduction of IL-13 as the primary outcome. METHODS: A double-blind, placebo-controlled parallel study was performed in which 62 subjects with a proven birch-pollen allergy consumed one of five different probiotic yoghurts containing four Lactobacillus plantarum strains and one Lactobacillus casei strain or a placebo yoghurt. Blood samples were collected at the start and after 4 weeks. Several immune parameters were determined in serum and peripheral blood mononuclear cell cultures (PBMC) derived from these subjects. Results A decrease in birch-pollen-specific IgE was found for four probiotic strains. L. casei Shirota reduced the number of CD16(+) /CD56(+) cells in peripheral blood mononuclear cells. For strain L. plantarum CBS125632, the decrease in IgE coincided with significant decreases in IL-5 and IL-13 production by αCD3/αCD28-stimulated PBMC cultures. CONCLUSION AND CLINICAL RELEVANCE: Subjects with seasonal allergy can be used to determine immunomodulatory responses outside the pollen season within a 4-week study period. L. plantarum CBS125632 decreased several immune markers related to allergy, and may have the potential to alleviate the severity of seasonal allergy symptoms.

Cross-sectional and longitudinal relationships between alcohol consumption and lipids, blood pressure and body weight indices.

OBJECTIVE: Serum lipids, blood pressure and body mass may mediate the U-shaped relationship of alcohol consumption with type 2 diabetes mellitus and coronary heart disease. This study examines the cross-sectional and long-term longitudinal relationships of (changes in) alcohol consumption with (changes in) serum lipids, blood pressure and body mass indices. METHOD: In this prospective, observational cohort study, two measurements of alcohol consumption, serum total and high-density lipoprotein cholesterol, triglycerides, blood pressure, body weight, the thickness of four skinfolds and waist circumference were performed 4 years apart in healthy volunteers (143 men and 174 women, 32 years old at the first measurement). Alcohol consumption from beer, wine and distilled spirits was assessed using an extensive dietary history interview. Linear regression analyses were performed to study the cross-sectional relationships between the amount of alcohol consumed at the age of 32 years and the levels of the lipids, blood pressure and body weight indices, and to study the longitudinal relationships between the changes in the amount of alcohol consumed over the 4 years of follow-up and the concurrent changes in the lipids, blood pressure and body weight indices. Nonlinearity was investigated for the cross-sectional relationships. RESULTS: A 10-g/day difference in alcohol consumption was positively related with a 0.05 mmol/L (1.9 mg/dl) difference in high-density lipoprotein cholesterol in both cross-sectional (p = .004), and longitudinal (p < .0001) analyses. This relationship did not differ for men and women or for the consumption of beer, wine or distilled spirits. Relationships with changes in total cholesterol, triglycerides, systolic, diastolic, and pulse pressure, body weight and the sum of four skinfolds were not significant. A borderline significant inverse longitudinal relationship was found with waist circumference. The other lifestyle behaviors (tobacco smoking, physical activity and dietary habits) were major confounders of most cross-sectional relationships between alcohol and serum lipids, blood pressure and body mass indices. The longitudinal relationships, however, were not confounded by changes in the other lifestyle behaviors. A significant nonlinear relationship was found for systolic blood pressure, in which drinkers of about 30 g/day had the lowest values. CONCLUSIONS: Moderate alcohol consumption and moderate long-term changes in alcohol consumption are positively related with the levels and changes in high-density lipoprotein cholesterol in healthy adult men and women. A moderate inverse association between alcohol and waist circumference may be expected. No relationships were found with triglycerides, blood pressure, body weight and the sum of the thickness of four skinfolds. Other lifestyle behaviors confound the cross-sectional, but not the longitudinal, relationships between alcohol consumption and serum lipids, blood pressure and body mass indices. Gender and type of beverage do not modify the relationships between alcohol consumption and these indices.

Heterogeneous suppression of experimentally induced colon cancer metastasis in rat liver lobes by inhibition of extracellular cathepsin B.

Metastatic rat colon cancer cells but not normal rat hepatocytes showed activity of cathepsin B on their plasma membranes. Activity was visualized in living cells with a new fluorogenic substrate, [Z-Arg]2-cresyl violet, and confocal microscopy. When these cancer cells were injected into the portal vein of rats, the animals developed tumors in the liver in a heterogeneous fashion. Three- to four-fold more tumors were found in the small caudate lobe than in the other three large lobes of the liver. Oral treatment with a selective water-soluble inhibitor of extracellular cathepsin B, Mu-Phe-homoPhe-fluoromethylketone, resulted in 60% reduction of the number of tumors and 80% reduction of the volume of tumors in the three large lobes whereas tumor development was not affected in the small caudate lobe. This study supports the conclusions that (a) extracellular cathepsin B plays a crucial but complex role in liver colonisation by rat colon carcinoma cells in vivo, (b) its selective inhibition suppresses tumor growth heterogeneously in the liver and (c) the caudate lobe of the liver is a relatively large risk factor for tumor development.

Quantification of antigen-specific immunoglobulin A after oral booster immunization with ovalbumin in mice mono-associated with segmented filamentous bacteria or Clostridium innocuum.

Segmented filamentous bacteria (SFB) are known to stimulate the mucosal immune system. Here, the effect of SFB on oral booster immunization with ovalbumin was investigated. Mice mono-associated with SFB or Clostridium innocuum were sensitized by intraperitoneal administration of 100 micrograms ovalbumin with Freunds complete adjuvant. After 4 weeks, mice received 80 mg ovalbumin orally. A maximum IgA response was found 5 days after this booster immunization. Comparison of mice with SFB and mice with C. innocuum revealed a much higher level of IgA in the gut lumen and more IgA secreting cells in the lamina propria of the SFB-associated mice. However, no differences between both groups of animals were found in specific levels of IgA secreting cells or luminal IgA against ovalbumin. It is concluded that there is no enhancing effect of SFB after booster immunization when mice are primed intraperitoneally with ovalbumin.

Does DGAVP influence memory, attention and mood in young healthy men?

The influence of an increasing dose of the vasopressin-like peptide DGAVP (desglycinamide-arginine-vasopressin) on memory was investigated in two groups of ten healthy male volunteers to provide information about the hypothesis of improvement of memory by vasopressin. At the same time we evaluated the effect of DGAVP on mood, alertness or sleepiness in a double-blind placebo-control design. The treatment group received at 9.15 a.m. intranasally a daily increasing dose from 0.1 mg at day 1 to 10.0 mg at day 5. DGAVP did not significantly affect any measure of memory or alertness. DGAVP did, however, produce a significant increase in concentration level and mood. The results of the present study provide no support for the vasopressin theory of memory improvement; rather, the results direct the attention to attention modulating effects.

Influence of caffeine on information processing stages in well rested and fatigued subjects.

The effects of caffeine on different information processing stages were examined by using choice reaction time tasks. Independent variables were stimulus degradation, stimulus-response compatibility, time-uncertainty, state of the subject, and caffeine treatment. The task variables were assumed to affect the following processing stages; encoding, response selection and motor preparation, respectively. A 200 mg dose at the beginning of the experiment and a maintenance dose of 50 mg caffeine or lactose half-way through the session were administered to well rested and fatigued subjects, double-blind and deceptively. Behavioural measurements, event-related potentials (ERPs) and mood questionnaires were used to assess caffeine effects. The data showed that caffeine shortened reaction time. This effect showed an interaction with stimulus degradation and time uncertainty. In addition, ERP results supported the view that caffeine increases cortical arousal and perceptual sensitivity. Stimulating effects of caffeine were mainly located at input and output stages of the information processing system. Central processes were unaffected by caffeine. Fatigued subjects showed larger improvements in performance after caffeine than well-rested subjects. The results also indicated that caffeine effects were not stimulating in all subjects: 6 out of 30 subjects did not show arousing effects of caffeine.

The influence of caffeine on spatial-selective attention: an event-related potential study.

OBJECTIVES: Following the indications of previous studies that caffeine might have a specific effect on the processing of spatial information compared with other types of information, the present study investigated the influence of caffeine on an often used spatial-selective attention task. METHODS: Event-related potentials (ERPs) were recorded from 11 participants under conditions of caffeine (250 mg) and placebo. RESULTS: Spatial-selective attention effects were reflected in the ERPs as more positive going occipital P1 and broadly distributed P2 components, and more negative going occipital-temporal N1 and broadly distributed N2 components. A treatment effect was found as a more positive going frontal P2 component in the caffeine condition, whereas interactions between treatment and attention were observed for P2 and N2 components, but not for P1 and N1 components. CONCLUSIONS: This pattern of results suggests that caffeine has no specific influence on spatial-selective attention, but rather, has a more general facilitating effect on perceptual processing, as well as a possible effect on the frontal control mechanisms, i.e. focusing attention and increasing selectivity.

Efficiency of light utilization of Chlamydomonas reinhardtii under medium-duration light/dark cycles.

The light regime inside a photobioreactor is characterized by a light gradient with full (sun)light at the light-exposed surface and darkness in the interior of the bioreactor. Consequently, depending on the mixing characteristics, algae will be exposed to certain light/dark cycles. In this study the green alga Chlamydomonas reinhardtii was cultivated under five different light regimes: (1) continuous illumination; (2) a square-wave light/dark cycle with a light fraction (epsilon) of 0.5 and a duration (t(c)) of 6.1 s; (3) epsilon=0.5, t(c)=14.5 s; (4) epsilon=0.5, t(c)=24.3 s and (5) epsilon=0.8, t(c)=15.2 s. The biomass yield on light energy, protein per photons, decreased under light/dark cycles (epsilon=0. 5) in comparison to continuous light (CL), from 0.207 (CL) to 0.117-0.153 g mol(-1) (epsilon=0.5). Concomitantly, the maximal specific photosynthetic activity, oxygen production per protein, decreased from 0.94 (CL) to 0.64-0.66 g g(-1) h(-1) (epsilon=0.5). Also the quantum yield of photochemistry, yield of the conversion of light energy into chemical energy, decreased from 0.47 (CL) to 0. 23 (epsilon=0.5, t(c)=24.3 s). Apparently, C. reinhardtii is not able to maintain a high photosynthetic capacity under medium-duration light/dark cycles and since specific light absorption did not change, light utilization efficiency decreased in comparison to continuous illumination.

Is calculating pack-years retrospectively a valid method to estimate life-time tobacco smoking? A comparison between prospectively calculated pack-years and retrospectively calculated pack-years.

AIMS: To investigate the relative validity of retrospectively calculated pack-years (py-retro) by comparing py-retro with prospectively calculated pack-years (py-pro). DESIGN: A 23-year ongoing cohort study (1977-2000). PARTICIPANTS: One hundred and fifty-four males and females, 13 years old in 1977 and 36 years old in 2000. SETTING: Amsterdam, the Netherlands. MEASUREMENTS: To calculate py-pro, current smoking and quitting efforts were investigated nine times in a period of 23 years with the help of an interview or a questionnaire. At the age of 36, subjects filled out a comprehensive questionnaire about their smoking history, to calculate py-retro. Individual differences between py-pro and py-retro were calculated. In addition, Cohen's kappa was calculated after categorising py-pro and py-retro into three groups. FINDINGS: (1) Py-retro does not under- or overestimate life-time tobacco smoking. (2) The relative validity of py-retro was moderate due to large individual differences between py-pro and py-retro. (3) The individual differences between py-pro and py-retro became larger, the higher the number of pack-years. (4) Mean difference (and 95% limits of agreement) between py-pro and py-retro was -0.039 (-5.23, 5.32) when average pack-years was < 5.2 and -1.17 (-10.00, 14.65) when pack-years > or = 5.2. 5. Cohen's kappa between categorized py-pro and py-retro was 0.79. CONCLUSIONS: Future researchers in the field of smoking should be aware of the moderate relative validity of py-retro. Categorizing py-retro into smoking groups results in a misclassification error that is smaller than the quantitative error in continuous py-retro, but goes together with a loss of information.

Quantitative in vivo analysis of the kinematics of carpal bones from three-dimensional CT images using a deformable surface model and a three-dimensional matching technique.

The purpose of this study was to obtain quantitative information of the relative displacements and rotations of the carpal bones during movement of the wrist. Axial helical CT scans were made of the wrists of 11 volunteers. The wrists were imaged in the neutral position with a conventional CT technique, and in 15-20 other postures (flexion-extension, radial-ulnar deviation) with a low-dose technique. A segmentation of the carpal bones was obtained by applying a deformable surface model to the regular-dose scan. Next, each carpal bone, the radius, and ulna in this scan was registered with the corresponding bone in each low-dose scan using a three-dimensional matching technique. A detailed definition of the surfaces of the carpal bones was obtained from the regular-dose scans. The low-dose scans provided sufficient information to obtain an accurate match of each carpal bone with its counterpart in the regular-dose scan. Accurate estimates of the relative positions and orientations of the carpal bones during flexion and deviation were obtained. This quantification will be especially useful when monitoring changes in kinematics before and after operative interventions, like mini-arthrodeses. This technique can also be applied in the quantification of the movement of other bones in the body (e.g., ankle and cortical spine).

Detection of the carpal bone contours from 3-D MR images of the wrist using a planar radial scale-space snake.

In this paper we consider the problems encountered when applying snake models to detect the contours of the carpal bones in 3-D MR images of the wrist. In order to improve the performance of the original snake model introduced by Kass [1], we propose a new image force based on one-dimensional (1-D) second-order Gaussian filtering and contrast equalization. The improved snake is less sensitive to model initialization and has no tendency to cut off contour sections of high curvature, because 1-D radial scale-space relaxation is used. Contour orientation is used to minimize the influence of neighboring image structures. Due to 1-D contrast equalization an intensity insensitive measure of external energy is obtained. As a consequence a good balance between internal and external energetic contributions of the snake is established, which also improves convergence. By incorporating this new image force into the snake model, we succeed in accurate contour detection, even when relatively high noise levels are present and when the contrast varies along the contours of the bones.

Subject-related risk factors for sports injuries: a 1-yr prospective study in young adults.

The purpose of this study was to investigate the importance of subject-related risk factors for sports injuries, taking exposure time into account. At baseline in 182 healthy males and females (27 yr) the following subject-related risk factors were assessed: body mass index (BMI), maximal oxygen uptake (direct treadmill measurement), seven aspects of neuromotor fitness (MOPER fitness test), strength of the hamstring and quadriceps muscles (CYBEX), having sustained a sports injury in the 12 months preceding the baseline measurement ("previous injury"), and 16 psychological and psychosocial factors (measured with 8 standard, valid, and reliable questionnaires). For 1 yr, subjects were asked to make daily entries on a monthly log concerning all sports activities exceeding an intensity of 4 MET and all sustained sport injuries. Completed logs were returned by 139 subjects (75 males and 64 females). Fifty-one injuries were registered in 41 subjects. The overall incidence rate (IR) was 3.7 sports injuries per 1000 h of sports participation (95% confidence interval 2.8-4.9). For various subcategories, the following IR per 1000 h of sports participation were calculated: contact sports IR = 11.0 (95% CI 7.4-16.3); noncontact sports IR = 2.3% (95% CI 1.6-3.3); competition IR = 13.4 (95% CI 8.7-20.6); and training IR = 2.8 (95% CI 1.6-5.1). Data were analyzed by stepwise multiple logistic regression. The following five variables were independent and significant (P < 0.05) predictors of risk in sustaining a sport injury: dominance (odds ratio (OR) = 1.71; 95% CI = 1.44-2.03), vital exhaustion (OR = 1.85; CI = 1.22-2.86), stressful life events (OR = 1.84; 95% CI = 1.10-311); these ORs were calculated for an increase of 10% of the range of obtained scores, starting at minimum value. For total sporting time, the OR was calculated by taking the group with a total sporting time below the median (4050 h) as a reference (OR = 6.87; 95% CI = 2.09-22.55). For previous injury, subjects that had not sustained a sports injury in the 12 months preceding the baseline measurements served as a reference for the calculation of the OR (OR = 9.41; 95% CI = 2.80-31.58). These findings confirm that both exposure time and previous injury are more important predictors of sports injuries than psychological, psychosocial, physiological, and anthropometrical factors.

Physical activity of young people: the Amsterdam Longitudinal Growth and Health Study.

PURPOSE: To describe the natural development of habitual physical activity behavior (HPA) of young Dutch male and female subjects between the ages of 13 and 27, using data from the Amsterdam Longitudinal Growth and Health Study. METHODS: HPA was measured by means of a structured interview at ages 13, 14, 15, 16, 21, and 27 and concerned all activities (at work, school, during leisure, organized and nonorganized sports, and active transportation) exceeding a level of intensity of 4 METs. Complete longitudinal data concern 98 female and 83 male subjects. MANOVA for repeated measurements were done for total HPA (expressed in min x wk(-1) and in METs x wk(-1)). Similar analyses were done for organized sports activities, leisure time activities, and all "other" activities separately (also min x wk(-1) and METs x wk(-1)), as well as for weekly time at three different levels of intensity of HPA, i.e. 4-7 MET (moderate), 7-10 MET (vigorous), and >10 MET (very vigorous). RESULTS: Our data showed regarding total HPA (min x wk(-1)) in male, but not in female, subjects a significant decrease in weekly time spent on HPA between the ages of 13 and 27. Regarding the three different levels of intensity in male and female subjects, a significant increase was found in time spent on moderate activities, where female subjects were spending significantly more time on moderate activities than male subjects; both in male and female subjects, a significant decrease was found in time spent on vigorous activities: in male subjects a significant decrease was found in time spent on very vigorous activities, whereas in female subjects time spent at this level of activity remained more or less stable. For the total weighted activity score (METs x wk(-1)), a significant decrease was found for both male (42%) and female subjects (17%). This decrease was significantly greater for male than for female subjects. Regarding more specific activities, it was found that in the course of time organized sports activities became relatively more important contributors to both weekly HPA time and energy expenditure, both in male and female subjects. CONCLUSIONS: Our data show a considerable decrease in HPA over a 15-yr period of time, both in male and female subjects. Differences between male and female subjects are predominantly caused by differences in time spent in moderate and very vigorous activities. In the course of time, organized sports activities became a relatively more important contributor of weekly HPA.

Positive and negative life events: the relationship with coronary heart disease risk factors in young adults.

OBJECTIVE: to investigate the influence of positive and negative life events (including daily uplifts and daily hassles) on several biological and lifestyle coronary heart disease (CHD) risk factors. METHODS: from the Amsterdam Growth and Health Longitudinal Study (AGHLS), a cross-section sample of 207 males and 231 females aged 32/33 years was used. RESULTS: hardly any associations were found between both positive and negative life events and biological CHD risk factors. On the other hand, daily uplifts and positive life events were positively related to lifestyle. For both positive and negative life events coping behaviour played a role in these relationships. Furthermore, it was shown that the associations of health-related variables with daily uplifts and hassles were comparable to those found for major positive and negative life events. CONCLUSION: This study could not fully determine whether or not different mechanisms play a role in the health benefits of positive life events compared to the health burdens of negative life events.

Changes in daily hassles and life events and the relationship with coronary heart disease risk factors: a 2-year longitudinal study in 27-29-year-old males and females.

To investigate the relationship between changes in daily hassles and life events and biological (lipoproteins, blood pressure, body fat, and body fat distribution) and lifestyle (physical activity, smoking and alcohol consumption) risk factors for coronary heart disease (CHD) 166 subjects were measured twice, at 27 and 29 years of age. The results showed that changes in daily hassles were positively related to changes in lipoprotein levels, daily physical activity, and to smoking behavior. These relationships were more pronounced for subjects with a "rigid" coping style and subjects with type A behavior. Changes in life events were also positively related to lipoprotein levels, but only for subjects with a "rigid" coping style and only when the subjective appraisal of life events was taken into account. It was concluded that the relationships seemed to be mediated by different coping styles and type A behavior, that daily hassles were more important in these relationships than life events, and that the relationships with biological CHD risk factors were not influenced by lifestyle.

Overview of gut flora and probiotics.

Scientific developments in recent years have opened new frontiers and enable a better understanding of the gastrointestinal tract (GIT) as a complex and delicately balanced ecosystem. This paper focuses on more recent information related to the microbial population of the GIT and its functional role in human physiology and health. Special attention is also given to modern approaches for improving or stabilising the intestinal system and its functioning by the deliberate application of viable microbial cultures, so-called 'probiotics', selected for special functional properties.

The influence of caffeine on sustained attention: an ERP study.

The present study investigated the effects of caffeine on sustained attention by measuring concentration and fatigue. Event-related potentials (ERPs) and behavioral measures were recorded from 12 participants who worked continuously for approximately 10 min in a self-paced reaction task under conditions of both caffeine (250 mg) and placebo. The ERP data revealed more positive frontal P2 and parietal P3 components in the caffeine condition. However, a combination of different indices of the behavioral data did not reveal any effects of caffeine intake. These results suggest that caffeine increases arousal, thereby reducing fatigue, as was observed in the ERP results. A probable explanation for the absence of any effects of caffeine in the behavioral data can be found in the demanding properties of the task that was used, thereby supporting evidence for more pronounced effects of caffeine in suboptimal conditions. In addition, these results appeal for an increase in the use of ERPs in drug research, in order to discover possible effects on the brain which do not necessarily result in behavioral changes.

Blood cholesterol levels of 32-year-old alcohol consumers are better than of nonconsumers.

Blood cholesterol levels are expected to be important factors in the causal pathway between alcohol consumption and CHD. The relation between alcohol consumption and blood cholesterol levels is investigated in 130 men and 145 women aged 32.4 years old (+/-1.0), from the Amsterdam Growth and Health Longitudinal Study. When controlled for gender, cholesterol levels at age 13.1 years, and lifestyle at adult age (smoking, physical activity, dietary habits), no significant differences were found for total cholesterol (TC) levels between alcohol consumers and nonconsumers. Serum high-density lipoprotein (HDL) cholesterol levels were 0.12 mmol/l higher in subjects consuming >/=100 grams of alcohol per week than in nonconsumers (p < 0.05). Regression coefficients of subjects consuming 10 to 50, or 50 to 100 g alcohol per week did not differ statistically from those of nonconsumers. The positive relation between alcohol consumption and serum HDL was modified by smoking (found in nonsmokers, but not in smokers). No differences between beer, wine, and spirits were found for their relation with serum HDL. In conclusion, 32.4-year-old nonsmoking subjects who consumed >/=100 g of alcohol per week had improved HDL levels compared with nonconsumers, whereas the protective effect of drinking smaller amounts of alcohol did not reach statistical significance.

P3 scalp topography to target and novel visual stimuli in children of alcoholics.

The P3 event-related potential (ERP) component was recorded from 7- to 18-year-old children of alcoholics (COAs, n = 50) and age- and sex-matched control children (n = 50) using a visual oddball paradigm, involving nontarget (76%), target (12%), and novel (12%) stimuli. Topographic maps of P3 and associated scalp current density were obtained to supplement a topographic profile analysis. COAs manifested a smaller amplitude P3 to target stimuli over the centroparietal, parietal, and occipital scalp locations than controls. Also, COAs exhibited a smaller amplitude P3 to novel stimuli over the occipital scalp than controls. There were no significant differences between COAs and controls in the P3 scalp topography, indicating that differences in intracranial source strength rather than in source configuration were responsible for the between-group amplitude differences. Also, no significant group differences were observed in the P3 peak latency or in behavioral performance. These results support the notion that the visual P3 may provide a vulnerability marker of alcoholism.

Age-related differences in timing of position and velocity identification.

The aim of this investigation was to study age-related differences in timing of position and velocity identification in a laboratory task. The skills required for performing this task are thought to be similar to those needed in real traffic situations. From this perspective, the results of this study may be taken into account in studies on accident analysis and prevention. To control for differences in the conscious experience of time and for simple reaction time to visual stimuli, young (25-34) and old (58-70) adults had to produce timed periods of 20 seconds and to time the arrival of a visible moving object at its goal. In these simple tasks no differences were found between young and old subjects. In the proper, more complex experiment, timing of position and velocity identification of a moving object were assessed with or without feedback on timing and velocity in the same old and young group. The object, moving from left to right at a constant velocity, was shown on a video screen during the first 40% of its trajectory. The moving object could have any of four (fixed) velocities which were presented in blocks with a regular or a mixed order. By pushing a button subjects estimated at which time the object would have reached the marked end of a trajectory. In a condition without feedback on timing of position, the timing error of older adults was higher than that of young adults and particularly with higher object velocities.(ABSTRACT TRUNCATED AT 250 WORDS)