The use of RT-PCR for determination of separate end-points for the strains IB H120 and IB D274 in titration of the combination vaccine Poulvac IB® primer.

Poulvac IB® Primer is a lyophilized vaccine containing two attenuated infectious bronchitis strains in one vial, IB H120 and IB D274. For quantification of the viral content of the vaccine, dilution series of the final product are inoculated in embryonated chicken eggs. After the incubation period of seven days standard practice is for the embryos to be taken from each egg and examined visually for IB specific lesions; these readings are used to determine an end-point in viral titrations. The result is a titre value to which both strains contribute. However, it is not clear what the live virus titre is for strain IB H120 and for strain IB D274. In order to determine end-points in the titration for each of the two strains, we collected the allantoic fluids from each egg after the incubation period and tested these for the presence of IB H120 and IB D274 by a strain specific reverse phase PCR. Based on the data obtained by PCR we were able to determine an end-point for each of the two strains. For a given commercial batch of Poulvac IB primer we determined titres of 10(6.31) EID50 per vial for IB H120 and 10(6.59) EID50 for IB D274 using PCR for end-point determination. These end-points matched well with the end-point determined for both strains cumulatively after visual examination, i.e. 10(6.67) EID50 per vial. It is concluded that PCR is a suitable means to determine end-points in titrations of live viruses.

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.

Biodiversity of mannose-specific adhesion in Lactobacillus plantarum revisited: strain-specific domain composition of the mannose-adhesin.

Recently, we have identified the mannose-specific adhesin encoding gene (msa) of Lactobacillus plantarum. In the current study, structure and function of this potentially probiotic effector gene were further investigated, exploring genetic diversity of msa in L. plantarum in relation to mannose adhesion capacity. The results demonstrate that there is considerable variation in quantitative in vitro mannose adhesion capacity, which is paralleled by msa gene sequence variation. The msa genes of different L. plantarum strains encode proteins with variable domain composition. Construction of L. plantarum 299v mutant strains revealed that the msa gene product is the key-protein for mannose adhesion, also in a strain with high mannose adhering capacity. However, no straightforward correlation between adhesion capacity and domain composition of Msa in L. plantarum could be identified. Nevertheless, differences in Msa sequences in combination with variable genetic background of specific bacterial strains appears to determine mannose adhesion capacity and potentially affects probiotic properties. These findings exemplify the strain-specificity of probiotic characteristics and illustrate the need for careful and molecular selection of new candidate probiotics.

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.

Three-dimensional carpal kinematics in vivo.

OBJECTIVE: The purpose of this study was to accurately quantify three-dimensional in vivo kinematics of all carpal bones in flexion and extension and radial and ulnar deviation. DESIGN AND METHODS: The right wrists of 11 healthy volunteers were imaged by spiral CT with rotational increments of 5 degrees during ulnar-radial deviation and of five of them also during flexion-extension motion. One regular-dose scan was used and the subsequent scans during wrist motion were performed with one-tenth of the regular dose. A three-dimensional matching technique using the internal structure of the bones was developed to trace the relative translations and rotations of the carpal bones very accurately. RESULTS: Most of our results are in concordance with previously published in vitro data. We could, among others, substantiate proof to the statement that there is more than one kinematic pattern of the scaphoid. Furthermore, we could accurately describe small adaptive intercarpal motions in vivo of the distal carpal row. CONCLUSIONS: To our knowledge, this is the first time the three-dimensional in vivo kinematics of all eight carpal bones is quantified accurately and non-invasively. RELEVANCE: Kinematics of an injured wrist can be compared to these reference data. It may become possible that in this way a ligament lesion can be detected with high specificity and sensitivity, and that no other diagnostic modality will be needed. With these data we made animations with which the complex movements of the bones during different motions of the wrist can be viewed. In the future it may become possible that this analysis provides valuable information on the long-term results of operative interventions and possibly predicts results of operative techniques.

Comparison of faecal Lactobacillus populations in experimental animals from different breeding facilities and possible consequences for probiotic studies.

AIMS: The effect of probiotic lactobacilli is likely dependent on the indigenous Lactobacillus strains in the intestinal tract. Since a substantial number of probiotic studies is performed in rodents, we compared the Lactobacillus strains of different rat and mouse populations in three animal facilities. METHODS AND RESULTS: SDS-PAGE and 16S rDNA analysis of cultured faecal lactobacilli revealed that different Lactobacillus strains were detected in genetically similar Wistar rats bred at different locations. Further, within the same animal facility host genetics did not affect the types of the predominant lactobacilli strains. CONCLUSIONS: Our results show that the environmental background of laboratory animals rather than host genetics determines the indigenous Lactobacillus strains that are found. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings underline the importance of microflora analysis in probiotic studies.

Smoking behaviour and biological maturation in males and females: a 20-year longitudinal study. Analysis of data from the Amsterdam Growth and Health Longitudinal Study.

PRIMARY OBJECTIVE: (1) Describe the longitudinal smoking behaviour of boys and girls during adolescence in relation to calendar age, skeletal age, years from peak height velocity (PHV) and years from menarche (in girls). (2) and (3) Investigate the timing of biological maturation (early or late maturation) in relation to smoking behaviour in adolescence and in adulthood (i.e. calendar age 32/33). HPOTHESIS: We hypothesized skeletal age, years from PHV and years from menarche to be better predictors of smoking than calendar age. RESEARCH DESIGN: This study is part of the Amsterdam Growth and Health Longitudinal Study (AGAHLS) that was started in 1977 with 619 pupils from two secondary schools (mean age 13.0 SD 0.6). METHODS AND PROCEDURES: Smoking behaviour was assessed four times between 1977 and 1980 and once in 1996/1997. Calendar age and skeletal age were measured annually whereas height and menarche were measured every 4 months. Maturation rate (skeletal age minus calendar age), age at PHV and age at menarche were used to estimate timing of biological maturation. Generalized Estimating Equation (GEE) analysis was used to study maturation rate in relation to smoking during adolescence, whereas logistic regression analyses were used to study mean maturation rate, years from PHV and years from menarche in relation to smoking in adulthood. OUTCOME AND RESULTS: Skeletal age, years from PHV and years from menarche are no better predictors of smoking during adolescence than calendar age. The prevalence of smoking rises gradually with the increase in all four estimates of biological maturation. Timing of biological maturation was positively related to smoking but only at calendar age 13 (OR 3.34, CI 1.58, 7.07). None of the three measures to estimate timing of biological maturation was significantly related to smoking status in adulthood.

Pisiform kinematics in vivo.

The purpose of this study was to quantify in vivo pisiform kinematics. Wrists of healthy volunteers were imaged by spiral computed tomography during ulnar-radial deviation (n = 11) and during flexion-extension (n = 5). Relative translations and rotations of the carpal bones were determined by using a 3-dimensional matching technique. The error of this registration procedure was less than 0.5 mm for translation and 0.4 degrees for rotation. With radial wrist deviation the pisiform flexes while the triquetrum extends; with ulnar deviation the triquetrum shows more ulnar deviation and extension. With wrist extension the pisiform translates over the distal part of the triquetrum while being pressed against it. With flexion the pisiform moves away from the triquetrum while translating proximally. These in vivo findings provide a further explanation for certain clinical entities, such as degenerative changes of the pisotriquetral joint, and may be used as a reference for normal kinematics of the pisiform.

Personality characteristics and alcohol consumption: longitudinal analyses in men and women followed from ages 13 to 32.

OBJECTIVE: The purpose of the present study was to investigate the relation between personality characteristics and alcohol consumption. Using a general population of young and generally healthy men and women, the focus was not on alcoholism but on the full scope of alcohol consumption, including abstinence and moderate levels of consumption. Modification of the relation between personality and alcohol consumption by gender, age and type of beverage was investigated. METHOD: The population consisted of 483 (259 female) subjects from the Amsterdam Growth and Health Longitudinal Study; they were aged 13 to 32 years over the 20-year course of the study, during which span measurements were taken between two and seven times. The longitudinal relation between five subscales of the Dutch Personality Inventory (DPI) and alcohol consumption were assessed with generalized estimating equations. RESULTS: Low prevalence of heavy alcohol consumption was found in this population. Abstinence from alcohol was more common among subjects who scored higher on Social Inadequacy, Rigidity and Self-sufficiency subscales. The amount of alcohol consumed was higher in drinkers who scored low on Rigidity and Social Inadequacy. Gender, age and type of alcoholic beverage modified some of the found relationships (e.g., adult women who scored high on Dominance were more likely to be the firmer wine drinkers). No significant relationships were found between alcohol consumption and the DPI Inadequacy subscale. CONCLUSIONS: Alcohol consumption was associated with lower scores on Social Inadequacy, Rigidity and Self-sufficiency.

Enhanced antigen-specific delayed-type hypersensitivity and immunoglobulin G2b responses after oral administration of viable Lactobacillus casei YIT9029 in Wistar and Brown Norway rats.

In this study, the effects of orally administered viable Lactobacillus casei Shirota strain YIT9029 on the immunity parameters of Wistar and Brown Norway rats were examined. For this purpose, we used the Trichinella spiralis host resistance model. Two weeks before and during T. spiralis infection, rats were fed 10(9) viable L. casei bacteria 5 days per week. The T. spiralis-specific delayed-type hypersensitivity (DTH) response was significantly enhanced in both Wistar and Brown Norway rats given L. casei. In both rat strains fed L. casei, serum T. spiralis-specific immunoglobulin G2b (IgG2b) concentrations were also significantly increased. In the model, no significant effects of L. casei on larval counts or inflammatory reactions in the tongue musculature, body weights, or lymphoid organ weights were observed. Serum specific antibody responses, other than IgG2b, were not changed by feeding of L. casei. In contrast to L. casei, it was shown that orally administered Bifidobacterium breve or Bifidobacterium bifidum had no influence on the measured infection and immunity indices in the rat infection model. Since the rat DTH response is considered to be a manifestation of Th1 cell-mediated immunity and the IgG2b isotype has been associated with Th1 activity, it was concluded that Th1 cells could play an active role in the immunomodulatory effects of orally administered L. casei. Furthermore, our data do not indicate that the effect of oral supplementation with L. casei is dependent on the genetic background of the host.

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.

Development and stability of alcohol consumption from adolescence into adulthood: the Amsterdam Growth and Health Longitudinal Study.

When studying long-term effects of alcohol consumption on health, the stability of alcohol consumption should be known. In this paper the development and stability of alcohol consumption were investigated. Seven measurements of alcohol consumption were carried out over a period of 20 years, starting at age 13 years, in a cohort of 65 men and 85 women. Effects of age, gender, and type of beverage on the stability of drinking as a dichotomous variable (drink or abstain) and on the stability of relative amounts of alcohol consumption were analyzed. The stability of the drink/abstain dichotomy was high (odds ratios>4) and increased with age. The stability of relative amounts of alcohol consumption was moderate (rS<0.6), and no effect of age was found. No sex effects were found, while the consumption of beer often showed higher stability than that of wine and spirits.

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.

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.

Transmission electron microscopic demonstration of phagocytosis and intracellular processing of segmented filamentous bacteria by intestinal epithelial cells of the chick ileum.

Segmented filamentous bacteria (SFB) are autochthonous bacteria colonizing the ileum of many young animals by attaching to intestinal epithelial cells. These nonpathogenic bacteria strongly stimulate the mucosal immune system and induce intestinal epithelial cells to express major histocompatibility complex class II molecules. We tried to discover whether SFB are phagocytized and intracellularly processed by the host cells, which is indicative of antigen processing. The middle part of the ileum was extracted from 10- and 20-day-old broiler chicks (Gallus gallus domesticus). Samples were processed and examined by scanning and transmission electron microscopy (SEM and TEM, respectively). In SEM, no, few, medium, and dense SFB colonization levels were classified. In TEM of cells from animals with medium or dense SFB colonization levels, we could observe extracellular particles ranging from those only indenting the cell membrane to particles found in the cytoplasmatic area beyond the terminal web. These particles had a structural similarity with SFB that were floating freely in the intestinal lumen. Furthermore, we observed unlacing of the membrane and septum surrounding the extracellular particles and their incorporation into host cytoplasmatic components, which strongly suggests that these particles are phagocytized and intracellularly processed SFB. This conclusion is supported by TEM analysis of samples with no or few SFB, in which we failed to find these characteristic morphologies. The phagocytosis process described here could be an important trigger for the stimulating effect of SFB on the mucosal immune system.

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.

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).

The effects of caffeine on visual selective attention to color: an ERP study.

Event-related potentials were recorded from 11 subjects after ingesting caffeine (250 mg) or placebo. Subjects were instructed to attend selectively to stimuli with a specified color (red or blue) in order to react to the occurrence of a target within the attended category. Reaction times revealed faster responses for the caffeine condition, whereas no differences in strategy were observed. Color attention effects were identified as frontal selection positivity, occipital selection negativity, and N2b, whereas target detection was reflected in P3b. Effects of treatment were found as a more positive-going frontal P2 component in the caffeine condition. In addition, an interaction between attention and treatment could be observed on the N2b component. This pattern of results suggests that caffeine yields a higher overall arousal level, more profound processing of both attended and unattended information, and an acceleration of motor processes.

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.