Pressure-jump X-ray studies of liquid crystal transitions in lipids

In this paper, we give an overview of our studies by static and time-resolved X-ray diffraction of inverse cubic phases and phase transitions in lipids. In 1, we briefly discuss the lyotropic phase behaviour of lipids, focusing attention on non-lamellar structures, and their geometric/topological relationship to fusion processes in lipid membranes. Possible pathways for transitions between different cubic phases are also outlined. In 2, we discuss the effects of hydrostatic pressure on lipid membranes and lipid phase transitions, and describe how the parameters required to predict the pressure dependence of lipid phase transition temperatures can be conveniently measured. We review some earlier results of inverse bicontinuous cubic phases from our laboratory, showing effects such as pressure-induced formation and swelling. In 3, we describe the technique of pressure-jump synchrotron X-ray diffraction. We present results that have been obtained from the lipid system 1:2 dilauroylphosphatidylcholine/lauric acid for cubic-inverse hexagonal, cubic-cubic and lamellar-cubic transitions. The rate of transition was found to increase with the amplitude of the pressure-jump and with increasing temperature. Evidence for intermediate structures occurring transiently during the transitions was also obtained. In 4, we describe an IDL-based 'AXCESS' software package being developed in our laboratory to permit batch processing and analysis of the large X-ray datasets produced by pressure-jump synchrotron experiments. In 5, we present some recent results on the fluid lamellar-Pn3m cubic phase transition of the single-chain lipid 1-monoelaidin, which we have studied both by pressure-jump and temperature-jump X-ray diffraction. Finally, in 6, we give a few indicators of future directions of this research. We anticipate that the most useful technical advance will be the development of pressure-jump apparatus on the microsecond time-scale, which will involve the use of a stack of piezoelectric pressure actuators. The pressure-jump technique is not restricted to lipid phase transitions, but can be used to study a wide range of soft matter transitions, ranging from protein unfolding and DNA unwinding and transitions, to phase transitions in thermotropic liquid crystals, surfactants and block copolymers.

Depression in men in the postnatal period and later child psychopathology: a population cohort study

Objective: Postnatal depression in women is associated with adverse effects on both maternal health and children's development. It is unclear whether depression in men at this time poses comparable risks. The present study set out to assess the association between depression in men in the postnatal period and later psychiatric disorders in their children and to investigate predisposing factors for depression in men following childbirth. Method: A population-based cohort of 10,975 fathers and their children from the Avon Longitudinal Study of Parents and Children (ALSPAC) was recruited in the prenatal period and followed for 7 years. Paternal depressive symptoms were assessed with the Edinburgh Postnatal Depression Scale and later child psychiatric disorder (DSM-IV) with the Development and Well-Being Assessment. Results: Depression in fathers in the postnatal period was significantly associated with psychiatric disorder in their children 7 years later (adjusted OR 1.72, 95% CI 1.07-2.77), most notably oppositional defiant/conduct disorders (adjusted OR 1.94, 95% CI 1.04-3.61), after adjusting for maternal depression and paternal educational level. A history of severe depression and high prenatal symptom scores for depression and anxiety were the strongest predictors of paternal depression in the postnatal period. Conclusions: Depression in fathers in the postnatal period is associated with later psychiatric disorders in their children, independently of maternal postnatal depression. Further research into the risks associated with paternal psychopathology is required because this could represent an important opportunity for public health intervention.

The effects of pre- and postnatal depression in fathers: a natural experiment comparing the effects of exposure to depression on offspring

Background: Depression in fathers in the postnatal period is associated with an increased risk of behavioural problems in their offspring, particularly for boys. The aim of this study was to examine for differential effects of depression in fathers on children's subsequent psychological functioning via a natural experiment comparing prenatal and postnatal exposure. Methods:In a longitudinal population cohort study (the Avon Longitudinal Study of Parents and Children (ALSPAC)) we examined the associations between depression in fathers measured in the prenatal and postnatal period (measured using the Edinburgh Postnatal Depression Scale), and later behavioural/emotional and psychiatric problems in their children, assessed at ages 31/2 and 7 years. Results: Children whose fathers were depressed in both the prenatal and postnatal periods had the highest risks of subsequent psychopathology, measured by total problems at age 31/2 years (Odds Ratio 3.55; 95% confidence interval 2.07, 6.08) and psychiatric diagnosis at age 7 years (OR 2.54; 1.19, 5.41). Few differences emerged when prenatal and postnatal depression exposure were directly compared, but when compared to fathers who were not depressed, boys whose fathers had postnatal depression only had higher rates of conduct problems aged 31/2 years (OR 2.14; 1.22, 3.72) whereas sons of the prenatal group did not (OR 1.41; .75, 2.65). These associations changed little when controlling for maternal depression and other potential confounding factors. Conclusions: The findings of this study suggest that the increased risk of later conduct problems, seen particularly in the sons of depressed fathers, maybe partly mediated through environmental means. In addition, children whose fathers are more chronically depressed appear to be at a higher risk of emotional and behavioural problems. Efforts to identify the precise mechanisms by which transmission of risk may occur should be encouraged to enable the development of focused interventions to mitigate risks for young children.

Geographies of food: 'Afters'

This third and final ‘Geographies of food’ review is based on an online blog conversation provoked by the first and second reviews in the series (Cook et al., 2006; 2008a). Authors of the work featured in these reviews – plus others whose work was not but should have been featured – were invited to respond to them, to talk about their own and other people’s work, and to enter into conversations about – and in the process review – other/new work within and beyond what could be called ‘food geographies’. These conversations were coded, edited, arranged, discussed and rearranged to produce a fragmentary, multi-authored text aiming to convey the rich and multi-stranded content, breadth and character of ongoing food studies research within and beyond geography.