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PubMed2004

Measurement of faecal immunoglobulin a levels in young children.

A nephelometric immunoassay was developed to quantify immunoglobulin A (IgA) in children's stools. This method enables IgA in faecal protein extracts to be measured over a large range of concentrations (1.61-51.50 mg/L) with good accuracy (linear recovery in dilution-overloading assay) and precision (within- and between-run coefficients of variation (CVs) of 1-6%). An excellent recovery (105%) was obtained in stool samples overloaded by purified colostral IgA, demonstrating that the method used for faecal IgA extraction is adapted, not to induce significant IgA degradation, and probably allow a complete extraction of IgA. The amount of faecal IgA, as determined in stool samples from 125 children (6-24 months old), was an average of 14 mg per 100 g of stools (about 10% of the total protein stool content), with large individual variation (3-30 mg per 100 g of stools). No correlation was observed between faecal IgA amounts and the children's age or sex. Such an immunoassay could enable exhaustive noninvasive investigations of the maturation of the intestinal immune system, as well as accurate studies of the effect of oral dietary supplementation on IgA regulation.

Child, Preschool↗
PubMed2003

Thinking and decision making, bacterial style: Bacterial Neural Networks, Obernai, France, 7th-12th June 2002.

Bacteria exhibit a bewildering range of behavioural responses and permutations of metabolic pathways for maximum exploitation of their environment. These are based on sensory perception of external and internal signals through batteries of surface and cytoplasmic receptors, evaluation of complex information flows and rapid decision making. Appreciation of the diversity of bacterial behaviour and adaptation capacities requires the study of a broad range of organisms and at this meeting we sampled more than 30 species with new findings which included the nature of gaseous receptors, advances in chemotaxis, subversion of host defences by pathogens, adaptation to high salt, community life and its obvious benefits, cell to cell communications and even the nature of bacterial circadian rhythms. With around 80 bacterial genomes now completed, and many more almost there, it was appropriate to complete the meeting with an introduction to Systems Biology and prospects for simulating the virtual cell. The versatility and seemingly 'intelligent' behaviour of bacteria will continue to fascinate, and this meeting on Bacterial Neural Networks fully reflected the excitement of this field.

Bacteria↗
PubMed1997

Review article: Intestinal epithelia and barrier functions.

The mucosal epithelia of the digestive tract acts as a selective barrier, permeable to ions, small molecules and macromolecules. These epithelial cells aid the digestion of food and absorption of nutrients. They contribute to the protection against pathogens and undergo continuous cell renewal which facilitates the elimination of damaged cells. Both innate and adaptive defence mechanisms protect the gastrointestinal-mucosal surfaces against pathogens. Interaction of microorganisms with epithelial cells triggers a host response by activating specific transcription factors which control the expression of chemokines and cytokines. This host response is characterized by the recruitment of macrophages and neutrophils at the site of infection. Disruption of epithelial signalling pathways that recruit migratory immune cells results in a chronic inflammatory response. The adaptive defence mechanism relies on the collaboration of epithelial cells (resident sampling system) with antigen-presenting and lymphoid cells (migratory sampling system); in order to obtain samples of foreign antigen, these samples must be transported across the barriers without affecting the integrity of the barrier. These sampling systems are regulated by both environmental and host factors. Fates of the antigen may differ depending on the way in which they cross the epithelial barrier, i.e. via interaction with motile dendritic cells or epithelial M cells in the follicle-associated epithelium.

Adaptation, Physiological↗
PubMed2005

The intergenerational transmission of perfectionism: parents' psychological control as an intervening variable.

The present study investigated the role of parental (adaptive and maladaptive) intrapersonal perfectionism as a predictor of parental psychological control and the role of parents' psychological control in the intergenerational transmission of perfectionism in a sample of female late adolescents and their parents. First, parental maladaptive perfectionism, but not parental adaptive perfectionism, significantly predicted parents' psychological control even when controlling for parents' neuroticism. This relationship was found to be stronger for fathers than for mothers. Second, a significant direct relationship was found between mothers' and daughters' maladaptive perfectionism but not between fathers' and daughters' maladaptive perfectionism. Third, process analyses showed that, for both mothers and fathers, psychological control is an intervening variable in the relationship between parents' and daughters' maladaptive perfectionism.

Adaptation, Psychological↗
PubMed1992

Effect of slow-release chlorhexidine mouthguards on the levels of selected salivary bacteria.

This study evaluated the effect of an alternate delivery system for chlorhexidine on salivary levels of mutans streptococci (MS) and other selected oral bacteria. On the basis of salivary MS levels > or = 10(4) CFU/ml, 22 subjects were enrolled. All caries lesions were restored prior to treatment. Two pretreatment paraffin-stimulated saliva samples were obtained for culturing at least 1 week apart. Complete-arch vacuum-adapted mouthguards were individually fabricated and coated internally with a 3% w/v chlorhexidine varnish. Mouthguards were worn for an average of 7 h/night for 7 nights. Saliva samples were obtained immediately after treatment and 1 and 3 months later. There was no significant change in levels of any of the monitored bacteria between the two pretreatment samples. A significant and specific reduction in salivary MS levels was observed in the three after-treatment samples as compared with baseline values (p < 0.001, p < 0.001, p < 0.05, respectively). The levels of Actinomyces viscosus were also measured, and there was a significant reduction immediately after treatment (p < 0.05), a return to baseline values at 1 month, and a significant increase above baseline values at 3 months, (p < 0.001). There was no significant change in saliva volume, in total numbers of facultatively anaerobic bacteria, or in levels of lactobacilli or Streptococcus sanguis. This treatment system is capable of significant and specific suppression of MS levels for up to 3 months without retreatment.

Actinomyces viscosus↗
PubMed2006

Volume density and distribution of mitochondria in harbor seal (Phoca vitulina) skeletal muscle.

Recent studies have shown that harbor seals (Phoca vitulina) have an increased skeletal muscle mitochondrial volume density that may be an adaptation for maintaining aerobic metabolism during diving. However, these studies were based on single samples taken from locomotory muscles. In this study, we took multiple samples from a transverse section of the epaxial (primary locomotory) muscles and single samples from the m. pectoralis (secondary locomotory) muscle of five wild harbor seals. Average mitochondrial volume density of the epaxial muscles was 5.6%, which was 36.6% higher than predicted for a terrestrial mammal of similar mass, and most (82.1%) of the mitochondria were interfibrillar, unlike athletic terrestrial mammals. In the epaxial muscles, the total mitochondrial volume density was significantly greater in samples collected from the deep (6.0%) compared with superficial (5.0%) regions. Volume density of mitochondria in the pectoralis muscle was similar (5.2%) to that of the epaxial muscles. Taken together, these adaptations reduce the intracellular distance between mitochondria and oxymyoglobin and increase the mitochondrial diffusion surface area. This, in combination with elevated myoglobin concentrations, potentially increases the rate of oxygen diffusion into mitochondria and prevents diffusion limitation so that aerobic metabolism can be maintained under low oxygen partial pressure that develops during diving.

Aerobiosis↗
PubMed2006

Development and validation of a platelet calcium flux assay using a fluorescent imaging plate reader.

Calcium signaling in platelets is an important physiological response to various aggregation stimuli. Loading platelets with various fluorescent dyes and measuring the change in calcium concentration using a spectrofluorometer has been the traditional approach to studying calcium signaling. This method suffers from the need for large platelet samples and a decrease in total fluorescence signal with time due to photobleaching. Therefore, it is rarely used to measure the quantitative effect of an agonist or antagonist on calcium signaling. Adaptation of these measurements to a fluorescent imaging plate reader (FLIPR) format allows the sample size to be reduced by 5- to 10-fold, and the microplate format allows a significant increase in throughput. Addition of the agonists to all wells simultaneously serves to normalize the total response. This article describes the first use of a FLIPR to study the calcium flux in human platelets. The IC(50) values showed a linear correlation with the K(i) for receptor binding in washed platelets. The generality of the methodology was shown by measuring EC(50) values for agonists and IC(50) values for antagonists of the platelet G protein-coupled receptor P2Y(1) and for the ion channel P2X(1).

Blood Platelets↗
PubMed2007

Increasing the sample size during clinical trials with t-distributed test statistics without inflating the type I error rate.

In clinical trials with t-distributed test statistics the required sample size depends on the unknown variance. Taking estimates from previous studies often leads to a misspecification of the true value of the variance. Hence, re-estimation of the variance based on the collected data and re-calculation of the required sample size is attractive. We present a flexible method for extensions of fixed sample or group-sequential trials with t-distributed test statistics. The method can be applied at any time during the course of the trial and does not require the necessity to pre-specify a sample size re-calculation rule. All available information can be used to determine the new sample size. The advantage of our method when compared with other adaptive methods is maintenance of the efficient t-test design when no extensions are actually made. We show that the type I error rate is preserved.

Computer Simulation↗
PubMedDate not supplied

The physical, behavioral, and psychosocial consequences of Internet use in college students.

The purposes of this study were to identify the physical, behavioral, and psychosocial consequences of Internet use in undergraduate college students; and to evaluate whether time, social norms, and adopter category predict the consequences of Internet use. Rogers' model for studying consequences of innovation was adapted for this study. A descriptive, correlational design was used. Convenience sampling yielded 293 undergraduate students who answered the online survey. Consequences of Internet use were assessed with the researcher-developed instrument, the Internet Consequences Scale (ICONS). Mean scores on the behavioral and psychosocial subscales of the ICONS indicated positive consequences of Internet use, while the physical consequences subscale revealed negative consequences. Multiple regression analyses revealed a small, but significant, amount of variance in consequences of Internet use that could be explained by time, social norms, and adopter category, thus supporting the adapted model for the study of consequences of Internet use in college students.

Adult↗
PubMed2004

Factor structure and concurrent validity of the Drug Use Screening Inventory in a community adolescent sample.

A variety of screening instruments for adolescent alcohol and drug abuse have been designed to be used within a clinical setting. This study adapted one of these instruments, the Drug Use Screening Inventory (DUSI), to be used within behavioral genetic or other epidemiological research on nonclinical samples. A primary goal of this study was to obtain a factor structure and set of subscales that might predict experimental and regular use of alcohol and drugs in a community sample. A secondary goal was to define subscales in a way that facilitated our interpretation and understanding of pathways to substance use and abuse. We investigated the underlying factor structure of items from four of the DUSI domains using a principal components analysis of the responses from 1266 adolescents from the Colorado Adolescent Twin Study. The resulting set of six subscales shows adequate internal consistency and provides an easily interpretable research tool for investigating etiological relationships between substance use problems and other risk behaviors.

Adolescent↗
PubMed1992

Measurement of marine picoplankton cell size by using a cooled, charge-coupled device camera with image-analyzed fluorescence microscopy.

Accurate measurement of the biomass and size distribution of picoplankton cells (0.2 to 2.0 microns) is paramount in characterizing their contribution to the oceanic food web and global biogeochemical cycling. Image-analyzed fluorescence microscopy, usually based on video camera technology, allows detailed measurements of individual cells to be taken. The application of an imaging system employing a cooled, slow-scan charge-coupled device (CCD) camera to automated counting and sizing of individual picoplankton cells from natural marine samples is described. A slow-scan CCD-based camera was compared to a video camera and was superior for detecting and sizing very small, dim particles such as fluorochrome-stained bacteria. Several edge detection methods for accurately measuring picoplankton cells were evaluated. Standard fluorescent microspheres and a Sargasso Sea surface water picoplankton population were used in the evaluation. Global thresholding was inappropriate for these samples. Methods used previously in image analysis of nanoplankton cells (2 to 20 microns) also did not work well with the smaller picoplankton cells. A method combining an edge detector and an adaptive edge strength operator worked best for rapidly generating accurate cell sizes. A complete sample analysis of more than 1,000 cells averages about 50 min and yields size, shape, and fluorescence data for each cell. With this system, the entire size range of picoplankton can be counted and measured.

Algorithms↗
PubMed1989

Construct validity of the adapted Questionnaire on Resources and Stress--short form.

The concurrent validity of the adapted version of Holroyd's (1982) short form of the Questionnaire on Resources and Stress (QRS) was examined with a sample of 103 mothers of children with mild to severe disabilities. A correlation matrix was generated using the QRS adapted short form total, its seven component factors, and six criterion measures. Results revealed significant relations among the criterion measures and their target factors as well as concurrence for the internal validity of the instrument.

Adaptation, Psychological↗
PubMed2002

Guardianship primavera: a first look at factors associated with having a legal guardian using a nationally representative sample of community-dwelling adults.

Although guardianship is an intrusive intervention that usually removes an adult's basic civil rights, studies of factors that place adults at risk for guardianship have largely been based on small studies of court files. While important and informative, these studies do not allow us to draw anything but tentative conclusions on risk factors for guardianship. The purpose of this article is to examine risk factors for having a legal guardian using a nationally representative sample for the first time. Logistic regression was conducted on the probability of having a legal guardian, using the Andersen model of health care utilization adapted for factors implied by the guardianship literature. The National Health Interview Supplement on Disability (1995) sample consisted of 65,013 adults aged 19 and older, and a sub-sample aged 60 and older (n = 13,784). Results indicate, first, that the prevalence of guardianship in community-dwelling adults is 0.3 percent, or over 750,000 people. Second, particularly for older adults, increasing age, having physical or emotional limitations, a small family network, and not living with a spouse are associated with having a guardian. Decreasing size of family networks and increasing marital disruption in future cohorts of older adults may suggest increasing need for legal guardianship. Further study should be conducted to replicate these findings in other large data sets and in extensive community studies.

Adult↗
PubMed1989

Childhood comorbidity of anxiety/affective disorders and behavior disorders.

Considerable data have been reported concerning comorbidity of various individual psychiatric disorders in children within the diagnostic supradomains of affect/anxiety disorders and behavior disorders as well as between these supradomains. To further examine such comorbidity, 35 psychiatrically hospitalized children were studied in terms of the prevalence of comorbidity, demographic and cognitive characteristics, adaptive functioning and maladaptive behaviors. The prevalence of comorbid behavior + affect/anxiety disorders exceeded 50% of the samples. Children with such comorbidity were similar to children with Behavior only diagnoses in terms of demographic and cognitive characteristics but differed in terms of adaptive functioning and maladaptive behaviors.

Anxiety Disorders↗
PubMed2005

The marginal quality of luted ceramic inserts in bovine teeth and ceramic inlays in extracted molars after occlusal loading.

PURPOSE: To compare the marginal adaptation of adhesively luted ceramic inserts in standardized cylindrical cavities of bovine dentin and enamel with the marginal adaptation of adhesively luted ceramic inlays in extracted molars after mechanical loading, and to calculate the minimum sample size required to differentiate between material groups based on the findings of this investigation. MATERIALS AND METHODS: Ceramic inserts of similar dimension were luted in standardized cylindrical cavities of bovine dentin and enamel (n = 6, O = 4 mm) with seven different adhesive/resin cement systems (Syntac/Variolink, Prime & Bond NT/Variolink, Excite DSC/Variolink, AdheSE/Variolink, Excite DSC/Multilink, Multilink Primer/ Multilink, RelyX Unicem). The same materials were used to lute ceramic inlays (Empress II) in three-surface cavities of extracted human molars (n = 6 per group). All specimens were submitted to 2000 cycles of thermocycling. In addition, restored teeth were submitted to cyclic loading (640,000 cycles, 50 N) in a chewing simulator. Replicas after stressing were analyzed with SEM, and the percentage of continuous margin of the inserts and the inlays was calculated, differentiating the proximal part of the inlay into cervical dentin/enamel and axio-proximal enamel. The mean percentage values per material group of the insert and inlay groups were ranked using relative ranks. Sample size estimation was done for pooled standard deviations comparing between two and seven materials and assuming 20% or 10% of the mean of continuous margin to be statistically significant. RESULTS: The Spearman correlation coefficient between the variables "insert dentin" and "inlay cervical dentin" was 0.71 (p = 0.07), between "insert enamel" and "inlay axio-proximal enamel" 0.07 (p = 0.9). The variability of the test results was large for both the insert and inlay variables, especially at the resin-dentin interface. No statistically significant difference between the materials could be found for the insert method when ANOVA and Bonferroni post-hoc tests were applied (p > 0.05), while the inlays luted with Prime & Bond NT/Variolink showed significantly less continuous margin at the cervical dentin than all other groups with the exception of RelyX Unicem. At least 16 (63) inlays and 14 (57) inserts had to be used per group for differences of 20% (10%) of the mean of continuous margin. CONCLUSION: To evaluate luting agents with regard to their ability to reduce marginal discrepancies, the inlay model is inadequate due to high sample numbers which make the test time-consuming and expensive; furthermore its clinical relevance is uncertain. Alternatively, the insert method may be a suitable screening method for dentinal margins, although its clinical relevance is also unknown.

Analysis of Variance↗
PubMed2007

The ongoing adaptive evolution of ASPM and Microcephalin is not explained by increased intelligence.

Recent studies have made great strides towards identifying putative genetic events underlying the evolution of the human brain and its emergent cognitive capacities. One of the most intriguing findings is the recurrent identification of adaptive evolution in genes associated with primary microcephaly, a developmental disorder characterized by severe reduction in brain size and intelligence, reminiscent of the early hominid condition. This has led to the hypothesis that the adaptive evolution of these genes has contributed to the emergence of modern human cognition. As with other candidate loci, however, this hypothesis remains speculative due to the current lack of methodologies for characterizing the evolutionary function of these genes in humans. Two primary microcephaly genes, ASPM and Microcephalin, have been implicated not only in the adaptive evolution of the lineage leading to humans, but in ongoing selective sweeps in modern humans as well. The presence of both the putatively adaptive and neutral alleles at these loci provides a unique opportunity for using normal trait variation within humans to test the hypothesis that the recent selective sweeps are driven by an advantage in cognitive abilities. Here, we report a large-scale association study between the adaptive alleles of these genes and normal variation in several measures of IQ. Five independent samples were used, totaling 2393 subjects, including both family-based and population-based datasets. Our overall findings do not support a detectable association between the recent adaptive evolution of either ASPM or Microcephalin and changes in IQ. As we enter the post-genomic era, with the number of candidate loci underlying human evolution growing rapidly, our findings highlight the importance of direct experimental validation in elucidating their evolutionary role in shaping the human phenotype.

Adolescent↗
PubMed2001

VD-AUTO-SMASH imaging.

Recently a self-calibrating SMASH technique, AUTO-SMASH, was described. This technique is based on PPA with RF coil arrays using auto-calibration signals. In AUTO-SMASH, important coil sensitivity information required for successful SMASH reconstruction is obtained during the actual scan using the correlation between undersampled SMASH signal data and additionally sampled calibration signals with appropriate offsets in k-space. However, AUTO-SMASH is susceptible to noise in the acquired data and to imperfect spatial harmonic generation in the underlying coil array. In this work, a new modified type of internal sensitivity calibration, VD-AUTO-SMASH, is proposed. This method uses a VD k-space sampling approach and shows the ability to improve the image quality without significantly increasing the total scan time. This new k-space adapted calibration approach is based on a k-space-dependent density function. In this scheme, fully sampled low-spatial frequency data are acquired up to a given cutoff-spatial frequency. Above this frequency, only sparse SMASH-type sampling is performed. On top of the VD approach, advanced fitting routines, which allow an improved extraction of coil-weighting factors in the presence of noise, are proposed. It is shown in simulations and in vivo cardiac images that the VD approach significantly increases the potential and flexibility of rapid imaging with AUTO-SMASH.

Artifacts↗