The cysteinyl leukotriene 2 receptor contributes to all-trans retinoic acid-induced differentiation of colon cancer cells

Background

Cysteinyl leukotrienes (CysLTs) are potent pro-inflammatory mediators that are increased in samples from patients with inflammatory bowel diseases (IBDs). Individuals with IBDs have enhanced susceptibility to colon carcinogenesis. In colorectal cancer, the balance between the pro-mitogenic cysteinyl leukotriene 1 receptor (CysLT₁R) and the differentiation-promoting cysteinyl leukotriene 2 receptor (CysLT₂R) is lost. Further, our previous data indicate that patients with high CysLT₁R and low CysLT₂R expression have a poor prognosis. In this study, we examined whether the balance between CysLT₁R and CysLT₂R could be restored by treatment with the cancer chemopreventive agent all-trans retinoic acid (ATRA).

Methods

To determine the effect of ATRA on CysLT₂R promoter activation, mRNA level, and protein level, we performed luciferase gene reporter assays, real-time polymerase chain reactions, and Western blots in colon cancer cell lines under various conditions.

Results

ATRA treatment induces CysLT₂R mRNA and protein expression without affecting CysLT₁R levels. Experiments using siRNA and mutant cell lines indicate that the up-regulation is retinoic acid receptor (RAR) dependent. Interestingly, ATRA also up-regulates mRNA expression of leukotriene C₄ synthase, the enzyme responsible for the production of the ligand for CysLT₂R. Importantly, ATRA-induced differentiation of colorectal cancer cells as shown by increased expression of MUC-2 and production of alkaline phosphatase, both of which could be reduced by a CysLT₂R-specific inhibitor.

Conclusions

This study identifies a novel mechanism of action for ATRA in colorectal cancer cell differentiation and demonstrates that retinoids can have anti-tumorigenic effects through their action on the cysteinyl leukotriene pathway.

Evaluation of the rapid loop-mediated isothermal amplification assay Illumigene for diagnosis of Clostridium difficile in an outbreak situation

An outbreak of Clostridium difficile infection (CDI) at Höglandet Hospital Eksjö in southern Sweden in 2011 was mainly due to a multidrug-resistant PCR ribotype 046 (30% of all samples). Diagnostics used routinely was the Vidas CDAB assay, but to control the outbreak the rapid loop-mediated isothermal amplification (LAMP) assay Illumigene was introduced and both techniques were compared to Toxigenic culture (TC) prospectively. The LAMP assay had a superior sensitivity, that is, 98% compared to 79% for the Vidas CDAB assay. Most importantly, the mean turn-around-time from collecting sample to result was reduced from 59 h to 2 h enabling early isolation of patients and effective hygiene precautions. This may potentially decrease the morbidity and nosocomial transmissions of C. difficile.

Microchannel acoustophoresis does not impact survival or function of microglia, leukocytes or tumor cells

BACKGROUND

The use of acoustic forces to manipulate particles or cells at the microfluidic scale (i.e. acoustophoresis), enables non-contact, label-free separation based on intrinsic cell properties such as size, density and compressibility. Acoustophoresis holds great promise as a cell separation technique in several research and clinical areas. However, it has been suggested that the force acting upon cells undergoing acoustophoresis may impact cell viability, proliferation or cell function via subtle phenotypic changes. If this were the case, it would suggest that the acoustophoresis method would be a less useful tool for many cell analysis applications as well as for cell therapy.

METHODS

We investigate, for the first time, several key aspects of cellular changes following acoustophoretic processing. We used two settings of ultrasonic actuation, one that is used for cell sorting (10 Vpp operating voltage) and one that is close to the maximum of what the system can generate (20 Vpp). We used microglial cells and assessed cell viability and proliferation, as well as the inflammatory response that is indicative of more subtle changes in cellular phenotype. Furthermore, we adapted a similar methodology to monitor the response of human prostate cancer cells to acoustophoretic processing. Lastly, we analyzed the respiratory properties of human leukocytes and thrombocytes to explore if acoustophoretic processing has adverse effects.

RESULTS

BV2 microglia were unaltered after acoustophoretic processing as measured by apoptosis and cell turnover assays as well as inflammatory cytokine response up to 48 h following acoustophoresis. Similarly, we found that acoustophoretic processing neither affected the cell viability of prostate cancer cells nor altered their prostate-specific antigen secretion following androgen receptor activation. Finally, human thrombocytes and leukocytes displayed unaltered mitochondrial respiratory function and integrity after acoustophoretic processing.

CONCLUSION

We conclude that microchannel acoustophoresis can be used for effective continuous flow-based cell separation without affecting cell viability, proliferation, mitochondrial respiration or inflammatory status.

Parental depression, maternal antidepressant use during pregnancy, and risk of autism spectrum disorders: population based case-control study

OBJECTIVE

To study the association between parental depression and maternal antidepressant use during pregnancy with autism spectrum disorders in offspring.

DESIGN

Population based nested case-control study.

SETTING

Stockholm County, Sweden, 2001-07.

PARTICIPANTS

4429 cases of autism spectrum disorder (1828 with and 2601 without intellectual disability) and 43,277 age and sex matched controls in the full sample (1679 cases of autism spectrum disorder and 16,845 controls with data on maternal antidepressant use nested within a cohort (n=589,114) of young people aged 0-17 years.

MAIN OUTCOME MEASURE

A diagnosis of autism spectrum disorder, with or without intellectual disability.

EXPOSURES

Parental depression and other characteristics prospectively recorded in administrative registers before the birth of the child. Maternal antidepressant use, recorded at the first antenatal interview, was available for children born from 1995 onwards.

RESULTS

A history of maternal (adjusted odds ratio 1.49, 95% confidence interval 1.08 to 2.08) but not paternal depression was associated with an increased risk of autism spectrum disorders in offspring. In the subsample with available data on drugs, this association was confined to women reporting antidepressant use during pregnancy (3.34, 1.50 to 7.47, P=0.003), irrespective of whether selective serotonin reuptake inhibitors (SSRIs) or non-selective monoamine reuptake inhibitors were reported. All associations were higher in cases of autism without intellectual disability, there being no evidence of an increased risk of autism with intellectual disability. Assuming an unconfounded, causal association, antidepressant use during pregnancy explained 0.6% of the cases of autism spectrum disorder.

CONCLUSIONS

In utero exposure to both SSRIs and non-selective monoamine reuptake inhibitors (tricyclic antidepressants) was associated with an increased risk of autism spectrum disorders, particularly without intellectual disability. Whether this association is causal or reflects the risk of autism with severe depression during pregnancy requires further research. However, assuming causality, antidepressant use during pregnancy is unlikely to have contributed significantly towards the dramatic increase in observed prevalence of autism spectrum disorders as it explained less than 1% of cases.

Abstract 1461: Two dimensional acoustic wave technology offers improved label free prostate cancer cell separation in blood

There is an unmet need for disease biomarkers that reliably predict clinical benefit in tumor recurrence in general and in castration resistant prostate cancer (CRPC) specifically. Isolation of rare circulating tumor cells (CTCs) has emerged as an increasingly important non-invasive tool in the pursuit for better-targeted therapies for patients with disseminating tumors.

We exploit ultrasound standing wave technology in a microchip setting, and have developed a third generation acoustophoretic microchip, which in time will allow isolation of CTCs from liquid biopsies from patients with advanced stages of prostate cancer. The separation device is a silicon/glass microchannel with trifurcation inlet and outlet, an incorporated pre-alignment channel and with temperature-stabilization. The novel system is now adapted to permit processing of sample volumes corresponding to clinical samples. A pressure driven system has been incorporated and runs the separation process. It mediates fewer fluctuations, generating even more stable separation results than previous setup,

Previously acoustic separation has been performed with WBCs diluted 1:10. However in this third generation setup it is possible to use samples of undiluted WBCs and there are indications that even concentrated WBC samples might generate similar results with maintained cancer cell recovery and separation performance. Larger sample volumes have allowed us to use lower amounts of spiked cancer cells and we can easily detect concentrations of less than 1000 spiked cancer cells per mL blood. This new setup generates acoustic separation with prostate cancer cell recoveries around 95% with 0,1% WBC contamination when processed at a flow rate of 100 μl/min.

It is possible to process both PFA fixed and non-fixed cells in the microchip. The acoustic separation method is gentle and does not affect cell viability, cell proliferation, androgen receptor function or PSA secretion. It is therefore an interesting alternative to current available techniques that require cell fixation. In addition we found that dead prostate cancer cells display different acoustic properties than viable cells, which makes it possible to distinguish live from dead cancer cells by acoustophoresis. This opens up for subsequent cell analysis requiring viable cells. New progressive techniques are needed to find and identify CTC populations independent on labeled cell-discrimination capacity, such as EpCAM negative CTCs. Acoustophoresis allows recovery of cancer cells independent of antigen expression, which allows for separation of novel EpCAM negative populations of CTCs with subsequent PCR analysis. It is therefore a promising method for future non-invasive molecular interrogation of metastatic cancers.

Citation Format: Cecilia Magnusson, Per Augustsson, Thomas Laurell, Hans Lilja. Two dimensional acoustic wave technology offers improved label free prostate cancer cell separation in blood. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1461. doi:10.1158/1538-7445.AM2013-1461

Deviance in fetal growth and risk of autism spectrum disorder

OBJECTIVE

Understanding the relationship between fetal growth and autism spectrum disorder (ASD) is likely to advance the search for genetic and nongenetic causes of ASD. The authors explored the associations between fetal growth, gestational age, and ASD with and without comorbid intellectual disability in a Scandinavian study population.

METHOD

The authors conducted a matched nested case-control study within the Stockholm Youth Cohort that included all children ages 0-17 who resided in Stockholm County from 2001 to 2007 (N=589,114). The authors identified 4,283 children with ASD: 1,755 with intellectual disability and 2,528 without, and they selected 36,588 age- and sex-matched comparison subjects. ASD case subjects were ascertained from unique identifiers assigned to all Swedish residents and linkage with official registers covering all pathways of assessment or care of ASD in Stockholm County. The authors calculated z scores of deviance in fetal growth from a reference curve using records from the national Swedish Medical Birth Registry, which included ultrasound dating of gestational age as well as birth weight. Crude and adjusted odds ratios for ASD, ASD with intellectual disability, and ASD without intellectual disability were the main outcome measures.

RESULTS

ASD risk increased with fetal growth 1.50 standard deviations below and >2.00 standard deviations above the mean for gestational age; the greatest risk was for fetal growth that was less than 2.00 standard deviations below the mean (adjusted odds ratio=1.70; 95% CI=1.44-2.01) or greater than 2.00 standard deviations above the mean (adjusted odds ratio=1.50; 95% CI=1.27-1.77). The same overall pattern was observed for ASD with and without intellectual disabilities. However, poor fetal growth (i.e., growth below the mean) was more strongly associated with ASD with intellectual disabilities than without. Regardless of fetal growth, preterm birth increased ASD risk.

CONCLUSIONS

Deviance in fetal growth at either distributional extreme may be a significant antecedent to the development of ASD through genetic and/or nongenetic mechanisms.

Family history of schizophrenia and bipolar disorder as risk factors for autism

CONTEXT

The clinical and etiologic relation between autism spectrum disorders (ASDs) and schizophrenia is unclear. The degree to which these disorders share a basis in etiology has important implications for clinicians, researchers, and those affected by the disorders.

OBJECTIVE

To determine whether a family history of schizophrenia and/or bipolar disorder is a risk factor for ASD.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a case-control evaluation of histories of schizophrenia or bipolar disorder in first-degree relatives of probands in 3 samples—population registers in Sweden, Stockholm County (in Sweden), and Israel. Probands met criteria for ASD, and affection status of parents and siblings for schizophrenia and bipolar disorder were established.

RESULTS

The presence of schizophrenia in parents was associated with an increased risk for ASD in a Swedish national cohort (odds ratio [OR], 2.9; 95% CI, 2.5-3.4) and a Stockholm County cohort (OR, 2.9; 95% CI, 2.0-4.1). Similarly, schizophrenia in a sibling was associated with an increased risk for ASD in a Swedish national cohort (OR, 2.6; 95% CI, 2.0-3.2) and an Israeli conscription cohort (OR, 12.1; 95% CI, 4.5-32.0). Bipolar disorder showed a similar pattern of associations but of lesser magnitude.

CONCLUSIONS

Findings from these 3 registers along with consistent findings from a similar study in Denmark suggest that ASD, schizophrenia, and bipolar disorder share common etiologic factors.

Adoptive paternal age and risk of psychosis in adoptees: a register based cohort study

The association between advancing paternal age and increased risk of schizophrenia in the off-spring is well established. The underlying mechanisms are unknown. In order to investigate whether the psychosocial environment associated with growing up with an aged father explains the increased risk we conducted a study of all adoptive children in Sweden from 1955-1985 (n =31 188). Their risk of developing schizophrenia or non-affective psychosis in relation to advancing age of their adoptive fathers' was examined. We found no association between risk of psychoses and advancing adoptive paternal age. There was no support of psychosocial environmental factors explaining the "paternal age effect".

Cohort profile: The Stockholm Public Health Cohort

The Stockholm Public Health Cohort was set up within the Stockholm County Council public health surveys to inform on determinants and consequences of significant contributors to the current burden of disease. Participants are 89 268 randomly selected individuals from the adult population of Stockholm County. Baseline surveys took place in 2002, 2006 and 2010 via self-administered questionnaires. So far, participants recruited in 2002 were re-surveyed twice, in 2007 and 2010, and those enrolled in 2006 were re-surveyed once, in 2010. Self-reported data are regularly supplemented by information from national and regional health data and administrative registers, for study participants and their relatives (including their offspring). Available data are extensive and include a wide array of health, lifestyle, perinatal, demographic, socio-economic and familial factors. The cohort is an international resource for epidemiological research, and the data available to the research community for specific studies obtained approval from the Stockholm Public Health Cohort Steering Committee and the Stockholm Regional Ethical Review Board.

Immigration, transition into adult life and social adversity in relation to psychological distress and suicide attempts among young adults

BACKGROUND

The increasing incidence of mental health problems among young people is a major concern in many Western countries. The causal mechanisms underlying these trends are not well established, but factors influenced by current societal changes ought to be implicated. Such factors include immigration and social adversity as well as the timing of taking on adult social roles (e.g. gainful employment, parenthood and own housing tenure). We therefore examined relationships between these factors and the risks of psychological distress as well as suicide attempts in young adults, with a focus on gender differences.

METHODS

We conducted a population-based study including 10,081 individuals aged 18-29, recruited in 2002 and 2006 in Stockholm, Sweden. Data were collected by record linkage and questionnaires.

RESULTS

Non-European immigrants had an increased risk of distress, and female non-European immigrants had a markedly higher risk of suicide attempts. Both early parenthood (≤ 24 years) and not being a parent, being a student and the lack of own housing tenure were associated with distress, but only in women. In both sexes, financial strain was associated with the increased risk of distress and suicide attempts, while unemployment was only associated with distress.

CONCLUSIONS

Immigration from outside Europe and social adversity are associated with mental health problems in young adults, especially females. Postponed transition into adulthood is associated with poor mental health in young women. These factors are influenced by current societal changes, and may have contributed to the increasing incidence of mental health problems among young people in Western countries.

The age- and sex-specific occurrence of bothersome neck pain in the general population--results from the Stockholm public health cohort

Background

Neck pain is very common but the occurrence of bothersome neck pain is not well described. Therefore our objective was to report on the prevalence and incidence of, as well as the rate of recovery from, bothersome neck pain in men and women of different ages in the general population.

Methods

We used data from a recently conducted population-based cohort study, comprising 23,794 individuals in Stockholm County, Sweden. Study participants were surveyed with a self-administered questionnaire in 2002/2003 and 2007, and information on episodes of neck pain was gathered at baseline and at follow-up. We then measured bothersome neck pain in 2005 and 2006 retrospectively in 2007 using the follow-up questionnaire.

Results

The one-year prevalence of bothersome neck pain for at least seven consecutive days was 25% (95% confidence interval (CI): 24–25) among women and 16% (95% CI: 15–16) among men, peaking in individuals aged 30–59 years. The one-year incidence proportion of bothersome neck pain was 7% (95% CI: 6–7) among women, and 4% (95% CI: 4–5) among men. Women recovered more infrequently than men. The one-year incidence proportion of recovery (of at least one year duration) was 11% (95% CI: 10–12) among women and 14% (95% CI: 12–16) among men.

Conclusion

Bothersome neck pain is most common in middle-aged individuals. Women are more likely than men to have and to develop bothersome neck pain, and less likely to recover from such pain. Younger men and women have a higher incidence, but recover more often from bothersome neck pain than older individuals.

Microfluidic, label-free enrichment of prostate cancer cells in blood based on acoustophoresis

Circulating tumor cells (CTC) are shed in peripheral blood at advanced metastatic stages of solid cancers. Surface-marker-based detection of CTC predicts recurrence and survival in colorectal, breast, and prostate cancer. However, scarcity and variation in size, morphology, expression profile, and antigen exposure impairs reliable detection and characterization of CTC. We have developed a noncontact, label-free microfluidic acoustophoresis method to separate prostate cancer cells from white blood cells (WBC) through forces generated by ultrasonic resonances in microfluidic channels. Implementation of cell prealignment in a temperature-stabilized (±0.5 °C) acoustophoresis microchannel dramatically enhanced the discriminatory capacity and enabled the separation of 5 μm microspheres from 7 μm microspheres with 99% purity. Next, we determined the feasibility of employing label-free microfluidic acoustophoresis to discriminate and divert tumor cells from WBCs using erythrocyte-lysed blood from healthy volunteers spiked with tumor cells from three prostate cancer cell-lines (DU145, PC3, LNCaP). For cells fixed with paraformaldehyde, cancer cell recovery ranged from 93.6% to 97.9% with purity ranging from 97.4% to 98.4%. There was no detectable loss of cell viability or cell proliferation subsequent to the exposure of viable tumor cells to acoustophoresis. For nonfixed, viable cells, tumor cell recovery ranged from 72.5% to 93.9% with purity ranging from 79.6% to 99.7%. These data contribute proof-in-principle that label-free microfluidic acoustophoresis can be used to enrich both viable and fixed cancer cells from WBCs with very high recovery and purity.

Migration and autism spectrum disorder: population-based study

BACKGROUND

Migration has been implicated as a risk factor for autism, but evidence is limited and inconsistent.

AIMS

To investigate the relationship between parental migration status and risk of autism spectrum disorder, taking into consideration the importance of region of origin, timing of migration and possible discrepancies in associations between autism subtypes.

METHOD

Record-linkage study within the total child population of Stockholm County between 2001 and 2007. Individuals with high- and low-functioning autism were defined as having autism spectrum disorder with and without comorbid intellectual disability, and ascertained via health and habilitation service registers.

RESULTS

In total, 4952 individuals with autism spectrum disorder were identified, comprising 2855 children with high-functioning autism and 2097 children with low-functioning autism. Children of migrant parents were at increased risk of low-functioning autism (odds ratio (OR) = 1.5, 95% CI 1.3-1.7); this risk was highest when parents migrated from regions with a low human development index, and peaked when migration occurred around pregnancy (OR = 2.3, 95% CI 1.7-3.0). A decreased risk of high-functioning autism was observed in children of migrant parents, regardless of area of origin or timing of migration. Parental age, income or obstetric complications did not fully explain any of these associations.

CONCLUSIONS

Environmental factors associated with migration may contribute to the development of autism presenting with comorbid intellectual disability, especially when acting in utero. High- and low-functioning autism may have partly different aetiologies, and should be studied separately.

Ribotyping of Clostridium difficile strains associated with nosocomial transmission and relapses in a Swedish County

Clostridium difficile is an emerging threat in hospital environments. To analyse possible transmission and to distinguish between relapse and reinfection a collection of C. difficile isolates, sampled from 162 consecutive episodes of C. difficile infection, were PCR ribotyped. Two ribotypes (001 and 012) were prone to cause nosocomial acquisition. Moreover, ribotype 001 had a tendency to cause relapses as almost one in two patients with this ribotype had one or more relapses. By using PCR ribotyping strains inclined to cause relapses and strains associated with hospital transmission might be detected. This enables optimized hygiene measures and may improve the choice of treatment regimen.

Autism spectrum disorders in the Stockholm Youth Cohort: design, prevalence and validity

OBJECTIVE

Reports of rising prevalence of autism spectrum disorders (ASD), along with their profound personal and societal burden, emphasize the need of methodologically sound studies to explore their causes and consequences. We here present the design of a large intergenerational resource for ASD research, along with population-based prevalence estimates of ASD and their diagnostic validity.

METHOD

The Stockholm Youth Cohort is a record-linkage study comprising all individuals aged 0-17 years, ever resident in Stockholm County in 2001-2007 (N = 589,114). ASD cases (N = 5,100) were identified using a multisource approach, involving registers covering all pathways to ASD diagnosis and care, and categorized according to co-morbid intellectual disability. Prospectively recorded information on potential determinants and consequences of ASD were retrieved from national and regional health and administrative registers. Case ascertainment was validated through case-note review, and cross validation with co-existing cases in a national twin study.

RESULTS

The 2007 year prevalence of ASD in all children and young people was 11.5 per 1,000 (95% confidence interval 11.2-11.8), with a co-morbid intellectual disability recorded in 42.6% (41.0-44.2) of cases. We found 96.0% (92.0-98.4) of reviewed case-notes being consistent with a diagnosis of ASD, and confirmed ASD in 85.2% (66.2-95.8) of affected twins.

CONCLUSIONS

Findings from this contemporary study accords with recently reported prevalence estimates from Western countries at around 1%, based on valid case ascertainment. The Stockholm Youth Cohort, in light of the availability of extensive information from Sweden's registers, constitutes an important resource for ASD research. On-going work, including collection of biological samples, will enrich the study further.

Use of snus and acute myocardial infarction: pooled analysis of eight prospective observational studies

The use of snus (also referred to as Scandinavian or Swedish moist smokeless tobacco), which is common in Sweden and increasing elsewhere, is receiving increasing attention since considered a tobacco smoke "potential reduction exposure product". Snus delivers a high dose of nicotine with possible hemodynamic effects, but its impact on cardiovascular morbidity and mortality is uncertain. The aim of this study was to investigate whether snus use is associated with risk of and survival after acute myocardial infarction (AMI). Data from eight prospective cohort studies set in Sweden was pooled and reanalysed. The relative risk of first time AMI and 28-day case-fatality was calculated for 130,361 men who never smoked. During 2,262,333 person-years of follow-up, 3,390 incident events of AMI were identified. Current snus use was not associated with risk of AMI (pooled multivariable hazard ratio 1.04, 95 % confidence interval 0.93 to 1.17). The short-term case fatality rate appeared increased in snus users (odds ratio 1.28, 95 % confidence interval 0.99 to 1.68). This study does not support any association between use of snus and development of AMI. Hence, toxic components other than nicotine appear implicated in the pathophysiology of smoking related ischemic heart disease. Case fatality after AMI is seemingly increased among snus users, but this relationship may be due to confounding by socioeconomic or life style factors.

Prenatal and early life exposure to stressful life events and risk of autism spectrum disorders: population-based studies in Sweden and England

Background and Aim

Exposure to stressful life events during pregnancy has been suggested as a potential risk factor for offspring Autism Spectrum Disorders (ASD), but the literature is limited and inconsistent. We tested the hypothesis that maternal exposure to stressful life events would be associated with increased risks of offspring ASD, and that these risks would be highest for exposures during the prenatal period.

Methods and Results

We used prospectively collected data from two large population based studies in Sweden and England. In the Swedish study of 4429 ASD cases and 43277 controls, our exposure comprised the occurrence of any severe life event before and during pregnancy and the child's early life. In the English study (maximum n = 11554, ASD n = 72), we studied the risk of offspring ASD in relation to a combined maternal exposure to multiple (up to 42) common and rare life events, as well as their perceived impact upon the mother during pregnancy and early life. In crude and adjusted regression analyses in both studies, we found no evidence of an association between prenatal life events, or their number and perceived impact and the risk of offspring ASD. Sub-group analysis of ASD with and without intellectual disability in the Swedish study yielded similar results.

Conclusion

We found no evidence to support the hypotheses that exposure to stressful life events during the prenatal period is associated with an increased risk of offspring ASD.

Degenerative changes of the temporomandibular joint. Relationship to ethnicity, sex and occlusal supporting zones based on a skull material

OBJECTIVE

The first aim of this study was to examine a contemporary human skull material for possible ethnic differences in respect of degenerative changes in the temporomandibular joints (TMJs). A second aim was to see if there was any correlation between such changes and occlusal support in any of the two groups and, if so, if this correlation was sex-related.

MATERIALS AND METHODS

The material consisted of 129 Caucasian skulls and 76 skulls from Afro-Americans. Ninety-four of the Caucasian skulls came from males (73%) and the corresponding figure for the Afro-Americans was 40 (53%). Their mean age at death was 46 years (range: 19-89 years) and 37 years (range: 18-70 years), respectively.

RESULTS

Dental status was in general poor and 13% of the Afro-Americans and 26% of the Caucasians were edentulous. Form and surface changes of the TMJs were more common in the present material compared to most previous studies. No differences could be found between the two ethnic groups in respect of degenerative joint changes in the TMJs. In men, no correlation of clinical relevance could be found between severity of joint changes and occlusal support. However, in both Caucasian and Afro-American women, such a correlation was obvious, especially in higher age.

CONCLUSIONS

The present findings give no evidence for any differences in the prevalence of degenerative changes in the TMJs in Caucasians and Afro-Americans. The strong correlation found between such changes and occlusal support in women but not in men might be explained by hormonal differences.

Acoustofluidics 8: applications of acoustophoresis in continuous flow microsystems

This acoustofluidics tutorial focuses on continuous flow-based half wavelength resonator systems operated in the transversal mode, where the direction of the primary acoustic force acts in plane with the microchip. The transversal actuation mode facilitates integration with up- and downstream microchannel networks as well as visual control of the acoustic focusing experiment. Applications of particle enrichment in an acoustic half wavelength resonator are discussed as well as clarification of the carrier fluid from undesired particles. Binary separation of particle/vesicle/cell mixtures into two subpopulations is outlined based on the different polarities of the acoustic contrast factor. Furthermore, continuous flow separation of different particle/cell types is described where both Free Flow Acoustophoresis (FFA) and binary acoustophoresis are utilized. By capitalizing on the laminar flow regime, acoustophoresis has proven especially successful in performing bead/cell translations between different buffer systems. Likewise, the ability to controllably translate particulate matter across streamlines has opened a route to valving of cells/particles without any moving parts, where event triggered cell sorting is becoming an increasing area of activity. Recent developments now also enable measurements of fundamental cell properties such as density and compressibility by means of acoustophoresis. General aspects on working with live cells in acoustophoresis systems are discussed as well as available means to quantify the outcome of cell and particle separation experiments performed by acoustophoresis.

Prenatal exposure to tobacco and future nicotine dependence: population-based cohort study

BACKGROUND

Maternal smoking during pregnancy may increase the risk of nicotine dependence, especially in girls, but data are conflicting and confounding by other familial factors cannot be ruled out.

AIMS

To clarify the relationship between prenatal tobacco exposure and adolescent tobacco uptake and dependence in boys and girls respectively, while taking confounding factors into close consideration.

METHOD

We conducted a prospective longitudinal study, comprising 3020 Swedish youths followed from 11 to 18 years of age. Exposure and outcome information was elicited via self-administered parental and repeated youth questionnaires. Hazard ratios (HRs), odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated as measures of associations.

RESULTS

Girls prenatally exposed to maternal tobacco use had a two- to threefold increased odds of experiencing a high number of withdrawal symptoms (OR = 2.83, 95% CI 1.68-4.87), craving for tobacco (OR = 2.04, 95% CI 1.28-3.32) and heavy tobacco use (five or more cigarettes or snus dips per day) (OR = 1.93, 95% CI 1.30-2.86). These associations were weaker among boys, and did not reach formal statistical significance. Associations between prenatal tobacco exposure and onset of regular tobacco use in both genders appeared to be mostly explained by parents' social position and postnatal smoking behaviour.

CONCLUSIONS

Prenatal exposure to tobacco is linked to an increased risk of nicotine dependence among adolescent girls.

Dangerous dads? Ecological and longitudinal analyses of paternity leave and risk for child injury

BACKGROUND

In 1974, Sweden became the first country to permit fathers to take paid parental leave. Other countries are currently following suit issuing similar laws. While this reform supports the principles of the United Nations convention of the right for children to be with both parents and enshrines the ethos of gender equality, there has been little systematic examination of its potential impact on child health. Instead, there is uninformed debate that fathers may expose their children to greater risks of injury than mothers. In this Swedish national study, the authors therefore assess whether fathers' parental leave can be regarded as a more serious risk factor for child injuries than that of mothers.

METHODS

Nationwide register-based ecological and longitudinal studies of hospitalisation due to injury (and intoxication) in early childhood, involving the Swedish population in 1973-2009 (ecological design), and children born in 1988 and 1989 (n=118 278) (longitudinal design).

RESULTS

An increase in fathers' share of parental leave over time was parallelled by a downward trend in child injury rates (age 0-4 years). At the individual level, the crude incidence of child injury (age 0-2 years) was lower during paternity as compared with maternity leave. This association was, however, explained by parental socio-demographic characteristics (multivariate HR 0.96, 95% CI 0.74 to 1.2).

CONCLUSION

There is no support for the notion that paternity leave increases the risk of child injury.