The Impact of Dietary Interventions on the Microbiota in Inflammatory Bowel Disease: A Systematic Review

BACKGROUND AND AIMS

Diet plays an integral role in the modulation of the intestinal environment, with the potential to be modified for management of individuals with inflammatory bowel disease [IBD]. It has been hypothesised that poor 'Western-style' dietary patterns select for a microbiota that drives IBD inflammation and, that through dietary intervention, a healthy microbiota may be restored. This study aimed to systematically review the literature and assess current available evidence regarding the influence of diet on the intestinal microbiota composition in IBD patients, and how this may affect disease activity.

METHODS

MEDLINE, EMBASE, Scopus, Web of Science, and Cochrane Library were searched from January 2013 to June 2023, to identify studies investigating diet and microbiota in IBD.

RESULTS

Thirteen primary studies met the inclusion criteria and were selected for narrative synthesis. Reported associations between diet and microbiota in IBD were conflicting due to the considerable degree of heterogeneity between studies. Nine intervention studies trialled specific diets and did not demonstrate significant shifts in the diversity and abundance of intestinal microbial communities or improvement in disease outcomes. The remaining four cross-sectional studies did not find a specific microbial signature associated with habitual dietary patterns in IBD patients.

CONCLUSIONS

Diet modulates the gut microbiota, and this may have implications for IBD; however, the body of evidence does not currently support clear dietary patterns or food constituents that are associated with a specific microbiota profile or disease marker in IBD patients. Further research is required with a focus on robust and consistent methodology to achieve improved identification of associations.

Assessing the Variability of the Twelfth Rib as a Landmark for Percutaneous Nephrolithotomy Using Computed Tomography

BACKGROUND

The variability in length of the twelfth rib is mentioned in the literature but has never been formally studied. The highly variable rib length provides a challenge for urologists seeking a consistent landmark for Percutaneous Nephrolithotomy (PCNL). We set out to determine whether the twelfth rib is safe to use as a consistent landmark for surgery.

METHODS

Single centre, cross-sectional retrospective observational study and analysis of CT scans of 100 adults who had imaging between 23rd March and 12th April 2020. The distance from the mid-sagittal line to the twelfth rib tip in the axial plane was measured as was the distance from the twelfth rib tip to the kidney, spleen and liver.

RESULTS

Length from the mid-sagittal line to the right twelfth rib tip varied from 46 (percentile 95% CI 40 to 57) to 136mm (percentile 95% CI 133 to 138). On the left, the distances varied from 55 (percentile 95% CI 50 to 64) to 134mm (percentile 95% CI 131 to 135). Twenty-three percent of people had an organ lying between the tip of the twelfth rib and the kidney on the right and 11% on the left.

CONCLUSION

The twelfth rib is highly variable in length. Similar variability was recorded in the distance from the tip to intra-abdominal organs. Due to the frequency of organs lying between the tip of the rib and the kidney it should not be used as a landmark for accessing the kidney without prior knowledge of an individual patient's anatomy as seen on imaging.

Irritable bowel syndrome - controversies in diagnosis and management

INTRODUCTION

The irritable bowel syndrome (IBS) is the best-recognized disorder of gut brain interactions (DGBI). However, it is controversial if the Rome IV criteria iteration for IBS diagnosis is fit for purpose.

AREAS COVERED

This review critically evaluates Rome IV criteria for diagnosis of IBS and addresses clinical considerations in IBS treatment and management, including dietary factors, biomarkers, disease mimics, symptom severity, and subtypes. The role of diet in IBS is critically reviewed along with the influence of the microbiota, including small intestinal bacterial overgrowth.

EXPERT OPINION

Emerging data suggest the Rome IV criteria are more suitable for identifying severe IBS and least useful for sub-diagnostic patients who are still likely to benefit from IBS treatment. Despite convincing evidence that IBS symptoms are diet-driven and often postprandial, a relationship to eating is not a Rome IV diagnostic criterion. Few IBS biomarkers have been identified, suggesting the syndrome is too heterogeneous to be measured by a single marker, and combined biomarker, clinical, dietary, and microbial profiling may be needed for objective characterization. With many organic diseases mimicking and overlapping with IBS, it's important clinicians are knowledgable about this to mitigate the risk of missing comorbid organic intestinal disease and to optimally treat IBS symptoms.

Gut health, the microbiome and dietary choices: An exploration of consumer perspectives

AIMS

To explore consumer perceptions regarding dietary behaviours related to the gut microbiome, to assist in effective translation of research to practice.

METHODS

Online focus groups were conducted (adults with no formal medical or nutrition training). Semi-structured open-ended questioning explored perspectives related to gut health and dietary behaviours. A qualitative descriptive analysis approach was undertaken in duplicate.

RESULTS

Fourteen focus groups were conducted (n = 38, 15 males, 23 females). Four overarching themes regarding consumer perceptions were identified. These were (a) gut health equates with wellbeing, (b) there are divergent perceptions of how diet influences gut health, (c) interest in scientific evidence does not necessarily influence dietary behaviour and (d) gastrointestinal symptoms influence dietary behaviour.

CONCLUSIONS

Consumers are interested in gut health and understand that diet may be important. Given that current literature regarding diet and gut health does not differ from dietary guidelines, consumer interest may provide a timely slant to promote longstanding guidelines. Consumer education to limit scepticism around government messaging, including utilisation of social media by nutrition professionals, may be key to improving adherence to guidelines.

Dietitians' perspectives on the role of dietetics practice in 'gut health'

AIMS

This study aimed to explore dietitians' perspectives on the evidence surrounding the relationship between diet and 'gut health' and the current and emerging role of dietetics practice in this area.

METHODS

A qualitative descriptive methodology was used. Online semi-structured interviews were conducted with Australian dietitians, focused on the perspectives related to gut health management in dietetics practice. Inductive thematic analysis was employed, commencing with initial coding by two researchers, and further coding leading to development of emergent themes. Divergent data were discussed and considered in analysis.

RESULTS

Fourteen interviews were conducted (2 males, 12 females). An overarching theme identified that current evidence is insufficient to direct dietetics practice change regarding gut health. Six subthemes on dietetics practice in 'gut health' emerged including (a) practice is multifaceted, (b) current practice aligns with dietary guidelines, (c) symptom management remains the primary concern, (d) evidence-based information is sought, (e) translational evidence is required for practice change and (f) there is a role for dietetics in gut health research and translation.

CONCLUSIONS

Dietitians do not appear confident in their practice regarding gut microbiome-related management and recognise there is currently limited translatable research to inform practice. Evidence to date suggests that recommendations for positive gut health do not differ substantially from Australian Dietary Guidelines. Dietitians will need additional education if further evidence emerges, however they demonstrated a strong commitment to evidence-based practice.

Establishing breast feeding in infants with Down syndrome: the FADES cohort experience

OBJECTIVE

To describe breastfeeding prevalence and maternal experience in infants with trisomy 21.

DESIGN

Longitudinal cohort study.

SETTING

Participants from UK recruited through websites, social media and local collaborators: neonatologists, community paediatricians and research nurses.

SUBJECTS

Infants under the age of 8 months with Down syndrome (DS) recruited to the Feeding and Autoimmunity in Down Syndrome Evaluation Study between 1 September 2014 and 31 August 2017. Seventy participants: median age 20 weeks (IQR 13-29 weeks) at initial questionnaire.

MAIN OUTCOME MEASURE

Breastfeeding prevalence at 6 weeks and 6 months among infants with DS.

RESULTS

The prevalence of exclusive breast feeding among study participants was similar to the general population (13/61, 21% vs 23% at 6 weeks, 2/54, 4% vs 1% at 6 months). However, the prevalence of breast feeding (exclusive or combination feeding) among the study participants was higher than the general population (39/61 64% vs 55% at 6 weeks, 32/59 54% vs 34% at 6 months).

CONCLUSION

Although there may be challenges in establishing breast feeding in infants with DS, our data suggest that exclusive breast feeding is possible for some, and the prevalence of breast feeding is comparable to the prevalence in the general population.

TRIAL REGISTRATION NUMBER

ISRCTN12415856.

Gut microbiome responses to dietary intake of grain-based fibers with the potential to modulate markers of metabolic disease: a systematic literature review

CONTEXT

Cereal fiber modulates the gut microbiome and benefits metabolic health. The potential link between these effects is of interest.0.

OBJECTIVE

The aim for this systematic review was to assess evidence surrounding the influence of cereal fiber intake on microbiome composition, microbiome diversity, short-chain fatty acid production, and risk factors for metabolic syndrome.

DATA SOURCES AND EXTRACTION

The MEDLINE, PubMed, CINAHL, and Cochrane Library databases were searched systematically, and quality of studies was assessed using the Cochrane Risk of Bias 2.0 tool. Evidence relating to study design, dietary data collection, and outcomes was qualitatively synthesized on the basis of fiber type.

DATA ANALYSIS

Forty-six primary publications and 2 secondary analyses were included. Cereal fiber modulated the microbiome in most studies; however, taxonomic changes indicated high heterogeneity. Short-chain fatty acid production, microbiome diversity, and metabolic-related outcomes varied and did not always occur in parallel with microbiome changes. Poor dietary data were a further limitation.

CONCLUSIONS

Cereal fiber may modulate the gut microbiome; however, evidence of the link between this and metabolic outcomes is limited. Additional research is required with a focus on robust and consistent methodology.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42018107117.

Spatial and Climatic Factors Influence Ambrosia Beetle (Coleoptera: Curculionidae) Abundance in Intensively Managed Plantations of Eastern Black Walnut

Invasive ambrosia beetles are among the most economically important pests of forest and plantation trees world-wide. The development of effective management guidelines for these pests in plantations of high-value hardwood species is hindered by a lack of baseline information regarding their seasonal abundance and dispersal behavior. By analyzing long-term monitoring data from intensively-managed plantations of eastern black walnut (Juglans nigra L.) in north-central Indiana, we identified key spatial and climatic variables that could improve the timing and precision of management actions to reduce ambrosia beetle populations. We also used geospatial analyses to compare species-specific spatial patterns of population density and evaluate the sensitivity of the trap density deployed in our long-term monitoring efforts. Xyleborinus saxesenii Ratzeburg and Xylosandrus crassiusculus Matschulsky (Coleoptera: Curculionidae) were more abundant during the spring in years preceded by a hot, dry growing season, and cold winter. Both species were positively associated with plantation edges during the fall flight period. However, X. saxesenii was less abundant in plantations close to forest corridors, whereas X. crassiusculus was more abundant in plantations closer to woodlots and other walnut plantations. Geospatial analysis revealed X. crassiusculus is active in larger, more spatially continuous patches than X. saxesenii, and that 200-m trap spacing is likely to be sufficient to detect both species in the spring flight period but may be insufficient to detect X. saxesenii during the fall flight period. Our findings underscore the power and utility of long-term monitoring to improve management strategies.

Does attrition affect estimates of association: A longitudinal study

Survey research frequently involves missing cases attributable to refusals to participate, lack of success in accessing all potential respondents or loss to follow-up in longitudinal studies. There is concern that those not recruited or those lost are a select group whose absence from a study may bias the findings of the study. This study provides a test of the extent to which selective loss to follow-up in a longitudinal study may lead to biased findings. The Mater-University Study of Pregnancy collected baseline information for 7718 pregnant women. Follow-ups occurred five years, 14 years, 21 years and 27 years after the birth, for 6753 eligible women. Participants at baseline were partitioned according to follow-up status for each follow-up. We compare baseline (at recruitment) measures of association, with these same measures of association for those retained in the study (Group A) and those lost to follow-up (Group B) at each phase of data. Using univariate logistic regression we compared the strength of association between maternal mental health and various baseline socio-demographic factors for different rates of loss to follow-up. Estimates of association at baseline, and at each follow-up are similar irrespective of the rate of loss to follow-up and whether the comparison is with those retained in the study or those lost to follow-up. There were no statistically significant differences in 90.8% of baseline comparisons with Group A, and 96.9% of comparisons with Group B measures of association. We conclude that differential loss to follow-up rarely affects estimates of association. We suggest that loss to follow-up may produce misleading findings only in circumstances where loss to follow-up is combined with a number of other sources of bias.

Young adult pregnancy status and the risk of developing overweight and obesity among women and men

Pregnancies can end in miscarriage, birth or termination. Although it is well known that pregnancy results in weight gain across the life course, it is unknown whether pregnancies which end in termination and miscarriage contribute to this. The study used a sub-sample of 3630 adult offspring from the original cohort of the Mater University of Queensland Study of Pregnancy (MUSP) and its outcomes, in Brisbane, Australia. Anthropometric data were measured at 5, 14 and 21 years of age and experience of pregnancy including termination, miscarriage and births were self-reported at 21 years. Multivariable analyses were conducted to determine whether pregnancy status of young people independently associated with overweight or obesity status. The women who had at least one birth were more likely to have overweight (odds ratio [OR] 1.52; 95% confidence interval [CI]: 1.01, 2.27) or obese (OR 2.38; 95% CI: 1.58, 3.59) compared to women who did not experience any pregnancy. Women whose pregnancies were terminated or miscarried were at the same risk of overweight or obesity as women who did not experience any pregnancy. For men, there is no association between the pregnancies in their partners and the mean difference in their body mass index. Young women whose pregnancies result in a birth, but not terminations or miscarriages, are at greater risk of having overweight or obesity following the birth.

What factors influence recruitment to a birth cohort of infants with Down's syndrome?

OBJECTIVE

To understand how to maximise recruitment of young infants with Down's syndrome (DS) into research through qualitative interviews with parents and care providers. In complex neonatal and genetic conditions such as DS, frequently diagnosed after birth, parents may go through a period of adaptation. These factors need consideration when overcoming barriers to recruitment.

PARTICIPANTS AND DESIGN

Participants, who were drawn from health professionals and volunteers working with families experiencing DS, were recruited using a purposive sampling strategy. Semistructured telephone interviews were completed with nine paediatricians, three research nurses and six family support workers. Five of those interviewed had a child with DS. The interviews were transcribed and analysed thematically.

RESULTS

A positive decision to take part in a 'from-birth' cohort study depends on factors such as the child's overall health, parent demographics (educational background and ethnicity), medical interactions that take place with the families (communication) and study logistics. The data suggest that recruitment methods need to take all these factors into consideration. Multiple recruitment methods should be considered including face to face, through parent and support groups, websites and social media. There also needs to be flexibility in the research timings to fit around the needs of the child and parents.

CONCLUSION

Researchers need to be aware of the variable responses elicited by families to a diagnosis of DS for their baby and be sensitive to the child's current medical status. This does not preclude recruitment into studies, but to maximise uptake good communication and flexibility is essential.

The association between adolescent psychopathology and subsequent physical activity in young adulthood: a 21-year birth cohort study

BACKGROUND

The beneficial effects of physical activity (PA) for both physical and mental wellbeing are well established. Given that adolescence presents a critical developmental period during which life-long patterns of PA become established, the exploration of the longitudinal impact of adolescent psychopathology on adult PA status is of interest.

METHODS

We analysed prospective data from 3663 young adults who participated in the Mater-University of Queensland Study of Pregnancy. Psychopathology was measured using the Youth Self-Report (YSR) at age 14. Participants' engagement in three types of PA (vigorous exercise, moderate exercise and walking) at age 21 were dichotomised into either 'none' or 'any'. For our main analysis, we examined the association between the YSR score and subsequent PA engagement using logistic regression. We also conducted sensitivity analyses of longitudinal associations between the YSR internalising and externalising symptoms score at age 14 and PA engagement at age 21.

RESULTS

We found no longitudinal association between the total YSR score at age 14 and PA engagement at age 21. In addition, there was no longitudinal association between the YSR internalising or externalising symptoms and PA engagement.

CONCLUSION

Our findings suggest that there is no longitudinal association between adolescent psychopathology and PA in young adulthood.

Maternal depression and family adversity: Linked pathways to offspring depression?

There is conflicting evidence about the contribution of maternal depression and family adversity to depression experienced by offspring. Because maternal depression and family adversity are related, there is a need to determine how they independently contribute to offspring depression. Data are from a long-running prospective birth cohort study (Mater-University of Queensland Study of Pregnancy and its outcomes - MUSP). For this study some 2200 offspring were followed up at 30 years of age. We first examine the association between maternal depression and family adversity over the period from the pregnancy to the child reaching adulthood. Then we consider the extent to which maternal depression and family adversity trajectories over this period predict CIDI/DSM-IV episodes of depression in the offspring of these mothers at 30 years of age. We find a strong bi-directional association between maternal depression and family experiences of adverse life events over the entire period the child is at home. After adjustment, children reared in a family experiencing high levels of adverse life events are more likely to experience a lifetime ever DSM-IV diagnosis of depression, are more likely to have experienced multiple episodes of lifetime ever depression, and are more likely to report their first episode of depression was at a younger age. The findings suggest the association between maternal depression and offspring depression appears to be partly attributable to the higher levels of family adversity characteristic of depressed mothers.

Beta cell function and ongoing autoimmunity in long-standing, childhood onset type 1 diabetes

AIMS/HYPOTHESIS

This study aimed to determine the frequency of residual beta cell function in individuals with long-standing type 1 diabetes who were recruited at diagnosis, and relate this to baseline and current islet autoantibody profile.

METHODS

Two hour post-meal urine C-peptide:creatinine ratio (UCPCR) and islet autoantibodies were measured in samples collected from 144 participants (median age at diagnosis: 11.7 years; 47% male), a median of 23 years (range 12-29 years) after diagnosis. UCPCR thresholds equivalent to mixed meal-stimulated serum C-peptide >0.001 nmol/l, ≥0.03 nmol/l and ≥0.2 nmol/l were used to define 'detectable', 'minimal' and 'residual/preserved') endogenous insulin secretion, respectively. Autoantibodies against GAD (GADA), islet antigen-2 (IA-2A), zinc transporter 8 (ZnT8A) and insulin (IAA) were measured by radioimmunoassay.

RESULTS

Endogenous C-peptide secretion was detectable in 51 participants (35.4%), including residual secretion in seven individuals (4.9%) and minimal secretion in 14 individuals (9.7%). In the 132 samples collected more than 10 years after diagnosis, 86 participants (65.2%) had at least one islet autoantibody: 42 (31.8%) were positive for GADA, 69 (52.3%) for IA-2A and 14 of 104 tested were positive for ZnT8A (13.5%). The level of UCPCR was related to age at diagnosis (p = 0.002) and was independent of diabetes duration, and baseline or current islet autoantibody status.

CONCLUSIONS/INTERPRETATION

There is evidence of ongoing autoimmunity in the majority of individuals with longstanding diabetes. Endogenous insulin secretion continues for many years after diagnosis in individuals diagnosed with autoimmune-mediated type 1 diabetes above age 5. These findings suggest that some beta cells are protected from continued autoimmune attack in longstanding type 1 diabetes.

Chimeric Allografts Induced by Short-Term Treatment With Stem Cell Mobilizing Agents Result in Long-Term Kidney Transplant Survival Without Immunosuppression: II, Study in Miniature Swine

Transplantation is now lifesaving therapy for patients with end-stage organ failure but requires lifelong immunosuppression with resultant morbidity. Current immunosuppressive strategies inhibit T cell activation and prevent donor-recipient engagement. Therefore, it is not surprising that few host cells are demonstrated in donor grafts. However, our recent small animal studies found large numbers of recipient stem cells present after transplantation and pharmacological mobilization, resulting in a chimeric, repopulated organ. We now confirm these findings in a well-characterized large animal preclinical model. Here, we show that AMD3100 and FK506 mobilization of endogenous stem cells immediately post kidney transplantation combined with repeat therapy at 1, 2, and 3 months led to drug-free long-term survival in maximally immunologically mismatched swine. Three long-term recipients have stable chimeric transplants, preserved antidonor skin graft responses, and normal serum creatinine levels despite withdrawal of all medication for 3 years.

The urinary bladder carcinogen propoxur does not produce genotoxic effects in the urinary bladder of Wistar male rats

Propoxur (PPX) is a carbamate insecticide which induced urinary bladder cancer in Wistar rats when fed at 5000ppm in Altromin 1321 diet (1321). In the present investigation, PPX was studied for induction of several key events related to modes of action (MOA) of carcinogenicity in urinary bladders (UBs). Wistar rats were administered the compound for 28 days at 8000ppm in Provini Liba SA 3883 diet, which is similar to the 1321 diet. o-Anisidine HCl (AH) was used as a genotoxic UB carcinogenic comparator, and trisodium nitrilotriacetate (NTA) as an epigenetic UB carcinogen comparator. Along with the non-dosed control and three test substance groups (PPX, AH, NTA), four more groups were additionally fed 2% ammonium chloride (AC) in the diet to acidify the urine, since 1321 was reported to increase urinary pH. AC did acidify the urine, as expected, although the 3883 diet itself did not increase pH values above 8. In the alkaline comet assay, AH produced DNA single strand breaks (SSBs) in the UB urothelium (UBU) irrespective of AC administration, whereas PPX and NTA did not. In the nucleotide (32)P-postlabeling assay (NPL), AH produced DNA adducts irrespective of AC administration, whereas PPX and NTA did not. Routine (H&E) histopathology evaluation of the UBU did not reveal any hyperplasia or evidence of luminal microprecipitates or calculi in any of the groups. Assessment of UBU proliferation as measured by immunohistochemistry of proliferating cell nuclear antigen, revealed that NTA and NTA plus AC increased the replicating fraction (RF). Also AH plus AC, but not AH alone, increased the RF of UBU, whereas PPX groups were not significantly different from controls. Thus, the results reveal no evidence for DNA SSBs, binding, or alteration of DNA synthesis in the UBU by PPX, while demonstrating UBU DNA damage by AH and showing that NTA does not damage DNA, but causes increased UBU proliferation. The findings are in accord with a genotoxic MOA for AH, and an epigenetic MOA for NTA. The MOA of PPX does not involve genotoxicity and may be specific to the 1321 diet.

Exome sequencing of pleuropulmonary blastoma reveals frequent biallelic loss of TP53 and two hits in DICER1 resulting in retention of 5p-derived miRNA hairpin loop sequences

Pleuropulmonary blastoma is a rare childhood malignancy of lung mesenchymal cells that can remain dormant as epithelial cysts or progress to high-grade sarcoma. Predisposing germline loss-of-function DICER1 variants have been described. We sought to uncover additional contributors through whole exome sequencing of 15 tumor/normal pairs, followed by targeted resequencing, miRNA analysis and immunohistochemical analysis of additional tumors. In addition to frequent biallelic loss  of TP53 and mutations of NRAS or BRAF in some cases, each case had compound disruption of DICER1: a germline (12 cases) or somatic (3 cases) loss-of-function variant plus a somatic missense mutation in the RNase IIIb domain. 5p-Derived microRNA (miRNA) transcripts retained abnormal precursor miRNA loop sequences normally removed by DICER1. This work both defines a genetic interaction landscape with DICER1 mutation and provides evidence for alteration in miRNA transcripts as a consequence of DICER1 disruption in cancer.

Successful transplantation of kidney allografts in sensitized rats after syngeneic hematopoietic stem cell transplantation and fludarabine

Current methods to remove donor-specific HLA antibody (DSA) from sensitized patients remain imperfect. We tested novel approaches to desensitization using an animal model of allogeneic sensitization with skin grafts from dark agouti (DA) to Lewis rats. At the peak IgG alloantibody response we transplanted DA kidneys into nephrectomized Lewis recipients (n = 6) and all died within 10 days from antibody-mediated rejection (AMR). Allogeneic hematopoietic stem cell transplants (HSCT) from DA donors failed to engraft after lethal or sub-lethal irradiation. Sensitized rats given lethal irradiation plus syngeneic green fluorescent protein (GFP) + HSCT had repopulation of blood, spleen, thymus and lymph nodes by GFP+ cells. At 2 months after HSCT, serum DSA levels were reduced 60-70% and DSA (IgG) production in cultured splenocytes was also significantly decreased. However, there was only a modest improvement in graft survival from an average of 6.5 to 13.9 (n = 9) days. Adding seven daily doses of fludarabine to the preconditioning regimen resulted in long-term survival (>90 days) in 7 out of 10 rat kidney allografts. We conclude that syngeneic HSCT performed after preconditioning with irradiation and fludarabine can reduce DSA, prevent DSA rebound and AMR, enabling successful transplantation in animals with strong antibody reactivity to the donor MHC.

A prospective study of cigarette smoking and basal cell carcinoma

To investigate the relationship between smoking and primary basal cell carcinoma (BCC), we analyzed data from a 16 year prospective study among randomly selected adults in Nambour, Queensland, Australia. Participants underwent a skin examination in 1992 and took part in an intervention study and follow-up. Information about complexion type and smoking habits including duration and number of cigarettes smoked per day and sun exposure behavior were collected at baseline in 1992, with updates to end of follow-up in 2007. Newly-diagnosed BCCs were ascertained from regional pathology laboratories. Relative risks (RR) of BCC among former and current smokers were estimated using generalized linear models specifying a Poisson distribution with robust error variance and (log) person-years at-risk as offset, adjusting for BCC risk factors. From 1992 to 2007, 281 BCCs were diagnosed in 1,277 participants with available smoking history and no past BCC. Relative to non-smokers, a non-significant inverse association between current smoking and BCC was seen (RR 0.69; 95 % CI 0.45-1.05) but not for former smokers (RR 1.05; 95 % CI 0.84-1.31). Amongst current smokers, inverse associations with BCC were found in those who smoked for up to 18 years (RR 0.44) but not more and those who smoked up to 15 cigarettes per day but not more. The associations with both current and former smoking varied by degree of sunburn propensity. The modest inverse association between current smoking and BCC is considered unlikely to be causal given lack of clear relation with duration or intensity of smoking.

Identification of key residues involved in adrenomedullin binding to the AM1 receptor

BACKGROUND AND PURPOSE

Adrenomedullin (AM) is a peptide hormone whose receptors are members of the class B GPCR family. They comprise a heteromer between the GPCR, the calcitonin receptor-like receptor and one of the receptor activity-modifying proteins 1-3. AM plays a significant role in angiogenesis and its antagonist fragment AM22-52 can inhibit blood vessel and tumour growth. The mechanism by which AM interacts with its receptors is unknown.

EXPERIMENTAL APPROACH

We determined the AM22-52 binding epitope for the AM1 receptor extracellular domain using biophysical techniques, heteronuclear magnetic resonance spectroscopy and alanine scanning.

KEY RESULTS

Chemical shift perturbation experiments located the main binding epitope for AM22-52 at the AM1 receptor to the C-terminal 8 amino acids. Isothermal titration calorimetry of AM22-52 alanine-substituted peptides indicated that Y52, G51 and I47 are essential for AM1 receptor binding and that K46 and P49 and R44 have a smaller role to play. Characterization of these peptides at the full-length AM receptors was assessed in Cos7 cells by cAMP assay. This confirmed the essential role of Y52, G51 and I47 in binding to the AM1 receptor, with their substitution resulting in ≥100-fold reduction in antagonist potency compared with AM22-52 . R44A, K46A, S48A and P49A AM22-52 decreased antagonist potency by approximately 10-fold.

CONCLUSIONS AND IMPLICATIONS

This study localizes the main binding epitope of AM22-52 to its C-terminal amino acids and distinguishes essential residues involved in this binding. This will inform the development of improved AM receptor antagonists.

The heritability of delusional-like experiences

OBJECTIVE

Delusional-like experiences (DLE) are common in the general community and are associated with a family history of mental illness. The aim of this study was to estimate the heritability of DLE.

METHOD

The Peter's Delusional Inventory (PDI) was administered to a population-based cohort of mothers (n = 2861, aged 35-67 years) and their adult offspring (n = 3079, aged 18-23 years). Heritability of DLE was estimated from the sum scores of the 21 item PDI under the assumption that the covariance between mother-offspring scores is attributable to shared additive genetic factors.

RESULTS

The means (medians and standard deviations) for the total PDI scores for the mothers and their offspring were 3.6 (3.0, 3.0) and 5.0 (4.0, 3.5), respectively. The Pearson correlation coefficient between mother and offspring PDI scores was 0.17 (P < 0.001). The heritability was estimated to be 0.35 (standard error 0.04).

CONCLUSION

Heritable factors contribute to over a third of the variance of PDI scores in this population. In light of the association between a family history of a wide range of mental disorders and DLE, these experiences may represent a useful quantitative endophenotype for genetic studies of common mental disorders in population settings.