Power of variance component linkage analysis to detect quantitative trait loci

Expressions are derived for the sample size required to achieve a given power in variance component linkage analysis of a quantitative trait in unascertained samples. For simplicity an additive model, comprising effects due to a single QTL, residual additive genetic factors, and individual-specific random environmental variation, is considered. Equations are given relating sample size to trait heritability for sibpairs, sib trios, nuclear families having two and three sibs, and arbitrary relative pairs. The effects of nonzero residual additive genetic variance and parental information are discussed, and a scale relationship for sample sizes with sibships and nuclear families is derived. For larger sampling structures such as extended pedigrees the inheritance space is randomly sampled and the relevant equations are solved numerically. Comparative power curves are presented for sibships of size 2–4 and for an extended pedigree of 48 individuals. Simulation results for sibpairs confirm the validity of the theoretical results.     

Genetics of platelet reactivity in normal,healthy individuals

Summary. Background: The Platelet Function Analyzer‐100 (PFA‐100) is widely used to measure platelet reactivity in whole blood under high shear. Objective: To characterize the genetic component of platelet reactivity among normal individuals, using the PFA‐100. Methods: We compared baseline platelet reactivity with sex, age, platelet count, hematocrit, plasma von Willebrand factor antigen (VWF:Ag), and alleles of seven candidate genes: integrin subunits α2 (ITGA2) and β3 (ITGB3), platelet glycoproteins GPIbα (GP1BA) and GPVI (GP6), purinogenic receptors (P2RY1 and P2RY12) and cyclooxygenase‐1 (COX1). Results: Based on linear and logistic regression models, we report an inverse correlation between baseline closure time (CT) initiated by collagen plus epinephrine (CEPI) and plasma VWF:Ag level, ITGA2 807T and P2RY1 893C, and an inverse correlation between baseline CT initiated by collagen plus adenosine diphosphate (CADP) and P2RY1 893C or GP1BA ‐5C. Conclusions: These results indicate that genetic polymorphisms in ITGA2 and P2RY1 combine with plasma VWF:Ag levels to modulate baseline platelet reactivity in response to collagen plus EPI, while genetic differences in P2RY1 and GP1BA significantly effect platelet responses to collagen plus ADP. Our results demonstrate that the PFA‐100 can be used to evaluate the effects of genetic predictors of platelet function.     

Health claims for food made in Australian magazine advertisements

Aim: The aim was to describe the level of health claims being used in magazine advertisements, the categories of foods carrying health claims, and the types of benefits being claimed for particular foods or food ingredients. Data were compared with similar studies of food labels and Internet sites to reflect the impact of rule governance of the different media and highlight implications for the current proposed changes in food standards legislation. Methods: From January to June 2005, a survey of all print advertisements for food in Australia's 30 top‐selling magazines was undertaken. The results were compared with those from a 1996 survey of health claims in Australian magazines and more recent surveys of claims for food on product labels and on Internet sites. Results: The survey found that 29.5% of 390 advertisements for food carried a health claim. Many of the claims were high‐level claims (29%) or therapeutic claims (8%), which are not permitted by current food standards. The most common benefits being promoted related to cardiovascular disease, energy, cancer and weight control, and most claims referred to the effect of the whole food, rather than specific ingredients. Results were similar to previous studies of food labels and Internet sites. Conclusion: Health claims are being used widely in the print advertising of food products in Australia. Moreover, the presence of high‐level and therapeutic claims in this media bears significant implications for the implementation of rules governing health claims on foods across the different media.     

A comparison of prostaglandin E2 pessaries and laminaria tents for ripening the cervix before termination of pregnancy

Summary. Forty primigravid womcn aged 15–45 years were randomly allocated to receive either an intravaginal pessary of 3 mg prostaglandin E, (PGE₂) or an intracervical 5-mm laminaria tent (LT) 12–16 h before termination of pregnancy at 6–14 weeks gestation. The degree of dilatation of the cervix a t operation and its resistance t o further dilatation during the procedure were assessed by a 'blind' operator. Laminaria tents were more effective in achieving dilatation and softening of the cervix than were PGE₂ pessaries and in 40% of women no further dilatation was necessary. There were no associated side-effects or complications. A cervical tear occurred in two of 20 patients treated with PGE₂ pessaries and all 20 required further dilatation of the cervix. Laminaria tents provide a simple. safe, acceptable and effective means of 'ripening' the cervix prior to termination of early pregnancy.     

Evidence for a role of cow's milk consumption in chronic functional constipation in children: Systematic review of the literature from 1980 to 2006

Aim:  This article examines the evidence for a role of cow's milk protein in chronic functional constipation in children.
Methods:  A literature search was conducted using Ovid and Pubmed, the Cochrane data bases, CINHAHL and EBSCO. Keywords searched included: constipation, cow's milk, intolerance, allergy, children and intestinal motility. This systematic review focused on dietary intervention studies in children (aged from 7 days to 15 years) with chronic functional constipation. All articles were required to include measures of cow's milk protein allergy or intolerance and include resolution of constipation as an outcome measure.
Results:  The keyword search identified 125 articles. Seven of these articles met the criteria for inclusion, including one double-blind, randomised controlled trial. The results of this review provide support for the hypothesis that a proportion of children with chronic functional constipation respond well to the removal of cow's milk protein from the diet, particularly if serum analysis shows abnormalities of immune mechanisms.
Conclusion:  The evidence surrounding cow's milk constipation was limited with only one of the assessed studies being at level II of evidence according to the NHMRC. In order to develop evidence-based guidelines, further high-level evidence is required to clarify the physiological, immunological and biochemical changes that occur in some constipated children who respond to the removal of cow's milk protein from the diet.     

Prediction of outcome of preterm infants with severe bronchopulmonary dysplasia

Abstract Forty-four preterm infants of less than 30 weeks gestation and birthweight £ 1250 g, with severe bronchopulmonary dysplasia requiring mechanical ventilation for at least 28 days, were reviewed. Twenty-seven infants (61%) survived; 17 died. There were no significant differences between survivors and non-survivors with respect to birthweight, gestational age, sex, Apgar score at 5 min or pulmonary diagnosis. Non-survivors displayed more severe changes on chest X-ray than the survivors. Peak inspiratory pressure (PIP), ventilator rate (VR), ventilator index and mean airways pressure were significantly higher in the non-surviving infants on days 2, 3, 4, 7, 14, 21 and 28, with non-survivors also having significantly higher alveolar-arterial oxygen gradients and lower arterial-alveolar oxygen ratios than the survivors. Discriminant analysis with cross-validation by pairing PIP and VR on day 28 produced a positive predictive value for non-survival of 88% and a negative predictive value of 89%. This result was better than was obtained for any other pair of ventilator parameter or oxygenation index. Discriminant analysis by combining X-ray appearances with ventilator settings did not improve the prediction. Having established a statistical model based on the PIP and VR of ventilator-dependent preterm infants on day 28, the outcome can be predicted with a high degree of confidence. This has the immediate potential application of indicating to staff in the neonatal unit a realistic approach to take when counselling parents of these infants.     

Factor structure of the Motivation Assessment Scale

The Motivation Assessment Scale (MAS) was developed to provide clinical information on four hypothesized functions that may control problem behaviour in persons with developmental disabilities. The original four-factor structure of the MAS was based on face validity, with the items being grouped in terms of each of the hypothesized functions. Validation of the scale was provided in terms of correlations between teacher ratings of eight children on the MAS and ranking of the controlling variables from functional analogue tests. In this study, staff in residential facilities rated 60 residents and teachers in schools rated 96 students on the MAS. The target behaviour rated for both samples was self-injury, with the institutional sample engaging in the behaviour more than 15 times an hour and the school sample, less than 15 times an hour. The results of factor analyses, with varimax rotation, provided a conceptually meaningful factor structure with the institutional sample, but not with the school sample. The 16 MAS items resolved into four factors that were conceptually related to four conditions that may maintain problem behaviour (i.e. sensory, escape, attention and tangible). The results suggested that the original MAS has a robust factor structure and may be clinically useful in predicting the controlling functions of problem behaviours, if the target behaviours occur at a rate no less than 15 responses per hour.     

Cannabis use correlates with schizotypy in healthy people

Cannabis use or high scores on self-report schizotypy questionnaires predict an increased risk of developing clinical psychosis. We tested whether cannabis use correlated with schizotypal and other personality traits in 211 healthy adults. Subjects who had used cannabis showed higher scores on schizotypy, borderline and psychoticism scales than never-users. Multivariate analysis, covarying lie scale scores, age and educational level indicated that high schizotypal traits best discriminated subjects who had used cannabis from never-users, whether or not they reported having used other recreational drugs. These results indicate that cannabis use is related to a personality dimension of psychosis-proneness in healthy people.     

Antibody responses to a 33 kDa cysteine protease of Trypanosoma congolense: relationship to 'trypanotolerance' in cattle

A cysteine protease of Trypanosoma congolense (congopain) elicited IgG1 antibodies in those cattle which exhibited a degree of resistance to disease during experimental infections (Authié et al. 1992, 1993). The aim of the present study was to investigate further the association between anti-congopain antibodies and resistance to trypanosomiasis, and to provide a lead into the mechanisms responsible for the differential responses to congopain in cattle. Isotype characteristics and kinetics of the antibody response to congopain were studied in three N'Dama (trypanoresistant) and three Boran (susceptible) cattle during primary infection with T. congolense ILNat 3.1. In both groups an IgM response to congopain was elicited, thus demonstrating that congopain is antigenic in both types of cattle. Most of the IgM appeared to be incorporated into immune complexes. IgG was detected as free antibody; IgG1 but not IgG2 was detected. All three N'Dama, but none of the three Boran cattle, mounted a significant IgG response to congopain. Sera from 70 primary-infected cattle belonging to five breeds of differing susceptibility were tested for their reactivity to congopain. High levels of IgG to congopain were observed in the two trypanotolerant breeds, whereas the three susceptible breeds had lower levels of these antibodies. Crosses between N'Dama and Boran cattle, which exhibit an intermediate susceptibility, had intermediate levels of antibodies. Thus, the results from experimental infections confirmed our initial observations. However, under natural tsetse challenge, repeated infections and trypanocidal treatments in Zebu cattle stimulated as high anti-congopain antibody levels as in non-treated trypanotolerant taurine cattle.