Associations between diet quality and dietary patterns and gestational diabetes mellitus in a low-risk cohort of pregnant women in Australia: a cross-sectional study

INTRODUCTION

Evidence of associations between the Mediterranean Diet Score (MDS) and Dietary Approaches to Stop Hypertension (DASH) score and gestational diabetes mellitus (GDM) in pregnant women is limited. This study examined changes in MDS and DASH and dietary patterns in Australian pregnant women between early and late pregnancy and their associations with GDM.

METHODS

The data from n = 284 participants were analysed. Diet quality indices and empirical dietary patterns were determined in early (15 ± 3 weeks gestation) and late pregnancy (35 ± 2 weeks gestation). Paired t-tests were used to examine changes in scores for diet quality indices and dietary patterns from early to late pregnancy. Logistic regression analysis was used to examine associations between GDM, diet quality indices and dietary patterns.

RESULTS

Three major dietary patterns were identified at early pregnancy. The first and second dietary patterns included unhealthier and healthier food groups, respectively, and the third comprised mixed food groups. Although diet quality scores did not change over time, consumption of the first dietary pattern increased (p = 0.01), and consumption of the second dietary pattern decreased by late pregnancy in women without GDM (p < 0.001).

CONCLUSION

No associations between DASH score, MDS and GDM were found; however an inverse association was observed between the first dietary pattern and GDM in late pregnancy (p = 0.023). Longitudinal studies are needed to examine diet quality and dietary patterns at early and late pregnancy to inform the development of tailored dietary advice for GDM.

A KLHL40 3' UTR splice-altering variant causes milder NEM8, an under-appreciated disease mechanism

Nemaline myopathy 8 (NEM8) is typically a severe autosomal recessive disorder associated with variants in the kelch-like family member 40 gene (KLHL40). Common features include fetal akinesia, fractures, contractures, dysphagia, respiratory failure and neonatal death. Here, we describe a 26-year-old man with relatively mild NEM8. He presented with hypotonia and bilateral femur fractures at birth, later developing bilateral Achilles' contractures, scoliosis, and elbow and knee contractures. He had walking difficulties throughout childhood and became wheelchair bound from age 13 after prolonged immobilization. Muscle magnetic resonance imaging at age 13 indicated prominent fat replacement in his pelvic girdle, posterior compartments of thighs and vastus intermedius. Muscle biopsy revealed nemaline bodies and intranuclear rods. RNA sequencing and western blotting of patient skeletal muscle indicated significant reduction in KLHL40 mRNA and protein, respectively. Using gene panel screening, exome sequencing and RNA sequencing, we identified compound heterozygous variants in KLHL40; a truncating 10.9 kb deletion in trans with a likely pathogenic variant (c.*152G > T) in the 3' untranslated region (UTR). Computational tools SpliceAI and Introme predicted the c.*152G > T variant created a cryptic donor splice site. RNA-seq and in vitro analyses indicated that the c.*152G > T variant induces multiple de novo splicing events that likely provoke nonsense mediated decay of KLHL40 mRNA explaining the loss of mRNA expression and protein abundance in the patient. Analysis of 3' UTR variants in ClinVar suggests variants that introduce aberrant 3' UTR splicing may be underrecognized in Mendelian disease. We encourage consideration of this mechanism during variant curation.

The mucosal barrier and anti-viral immune responses can eliminate portions of the viral population during transmission and early viral growth

Little is known about how specific individual viral lineages replicating systemically during acute Human Immunodeficiency Virus or Simian Immunodeficiency Virus (HIV/SIV) infection persist into chronic infection. In this study, we use molecularly barcoded SIV (SIVmac239M) to track distinct viral lineages for 12 weeks after intravenous (IV) or intrarectal (IR) challenge in macaques. Two Mafa-A1*063+ cynomolgus macaques (Macaca fascicularis, CM) were challenged IV, and two Mamu-A1*001+ rhesus macaques (Macaca mulatta, RM) were challenged IR with 200,000 Infectious Units (IU) of SIVmac239M. We sequenced the molecular barcode of SIVmac239M from all animals over the 12 weeks of the study to characterize the diversity and persistence of virus lineages. During the first three weeks post-infection, we found ~70–560 times more unique viral lineages circulating in the animals challenged IV compared to those challenged IR, which is consistent with the hypothesis that the challenge route is the primary driver restricting the transmission of individual viral lineages. We also characterized the sequences of T cell epitopes targeted during acute SIV infection, and found that the emergence of escape variants in acutely targeted epitopes can occur on multiple virus templates simultaneously, but that elimination of some of these templates is likely a consequence of additional host factors. These data imply that virus lineages present during acute infection can still be eliminated from the systemic virus population even after initial selection.

Prospective Evaluation of the Addition of Polygenic Risk Scores to Breast Cancer Risk Models

Background

The Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm and the International Breast Cancer Intervention Study breast cancer risk models are used to provide advice on screening intervals and chemoprevention. We evaluated the performance of these models, which now incorporate polygenic risk scores (PRSs), using a prospective cohort study.

Methods

We used a case-cohort design, involving women in the Melbourne Collaborative Cohort Study aged 50-75 years when surveyed in 2003-2007, of whom 408 had a first primary breast cancer diagnosed within 10 years (cases), and 2783 were from the subcohort. Ten-year risks were calculated based on lifestyle factors, family history data, and a 313-variant PRS. Discrimination was assessed using a C-statistic compared with 0.50 and calibration using the ratio of expected to observed number of cases (E/O).

Results

When the PRS was added to models with lifestyle factors and family history, the C-statistic (95% confidence interval [CI]) increased from 0.57 (0.54 to 0.60) to 0.62 (0.60 to 0.65) using IBIS and from 0.56 (0.53 to 0.59) to 0.62 (0.59 to 0.64) using BOADICEA. IBIS underpredicted risk (E/O = 0.62, 95% CI = 0.48 to 0.80) for women in the lowest risk category (<1.7%) and overpredicted risk (E/O = 1.40, 95% CI = 1.18 to 1.67) in the highest risk category (≥5%), using the Hosmer-Lemeshow test for calibration in quantiles of risk and a 2-sided P value less than  .001. BOADICEA underpredicted risk (E/O = 0.82, 95% CI = 0.67 to 0.99) in the second highest risk category (3.4%-5%); the Hosmer-Lemeshow test and a 2-sided P value was equal to .02.

Conclusions

Although the inclusion of a 313 genetic variant PRS doubles discriminatory accuracy (relative to reference 0.50), models with and without this PRS have relatively modest discrimination and might require recalibration before their clinical and wider use are promoted.

A System for Assessing Dual Action Modulators of Glycine Transporters and Glycine Receptors

Reduced inhibitory glycinergic neurotransmission is implicated in a number of neurological conditions such as neuropathic pain, schizophrenia, epilepsy and hyperekplexia. Restoring glycinergic signalling may be an effective method of treating these pathologies. Glycine transporters (GlyTs) control synaptic and extra-synaptic glycine concentrations and slowing the reuptake of glycine using specific GlyT inhibitors will increase glycine extracellular concentrations and increase glycine receptor (GlyR) activation. Glycinergic neurotransmission can also be improved through positive allosteric modulation (PAM) of GlyRs. Despite efforts to manipulate this synapse, no therapeutics currently target it. We propose that dual action modulators of both GlyTs and GlyRs may show greater therapeutic potential than those targeting individual proteins. To show this, we have characterized a co-expression system in Xenopus laevis oocytes consisting of GlyT1 or GlyT2 co-expressed with GlyRα₁. We use two electrode voltage clamp recording techniques to measure the impact of GlyTs on GlyRs and the effects of modulators of these proteins. We show that increases in GlyT density in close proximity to GlyRs diminish receptor currents. Reductions in GlyR mediated currents are not observed when non-transportable GlyR agonists are applied or when Na⁺ is not available. GlyTs reduce glycine concentrations across different concentration ranges, corresponding with their ion-coupling stoichiometry, and full receptor currents can be restored when GlyTs are blocked with selective inhibitors. We show that partial inhibition of GlyT2 and modest GlyRα₁ potentiation using a dual action compound, is as useful in restoring GlyR currents as a full and potent single target GlyT2 inhibitor or single target GlyRα₁ PAM. The co-expression system developed in this study will provide a robust means for assessing the likely impact of GlyR PAMs and GlyT inhibitors on glycine neurotransmission.

Repeated mild traumatic brain injury can cause acute neurologic impairment without overt structural damage in juvenile rats

Repeated concussion is becoming increasingly recognized as a serious public health concern around the world. Moreover, there is a greater awareness amongst health professionals of the potential for repeated pediatric concussions to detrimentally alter the structure and function of the developing brain. To better study this issue, we developed an awake closed head injury (ACHI) model that enabled repeated concussions to be performed reliably and reproducibly in juvenile rats. A neurological assessment protocol (NAP) score was generated immediately after each ACHI to help quantify the cumulative effects of repeated injury on level of consciousness, and basic motor and reflexive capacity. Here we show that we can produce a repeated ACHI (4 impacts in two days) in both male and female juvenile rats without significant mortality or pain. We show that both single and repeated injuries produce acute neurological deficits resembling clinical concussion symptoms that can be quantified using the NAP score. Behavioural analyses indicate repeated ACHI acutely impaired spatial memory in the Barnes maze, and an interesting sex effect was revealed as memory impairment correlated moderately with poorer NAP score performance in a subset of females. These cognitive impairments occurred in the absence of motor impairments on the Rotarod, or emotional changes in the open field and elevated plus mazes. Cresyl violet histology and structural magnetic resonance imaging (MRI) indicated that repeated ACHI did not produce significant structural damage. MRI also confirmed there was no volumetric loss in the cortex, hippocampus, or corpus callosum of animals at 1 or 7 days post-ACHI. Together these data indicate that the ACHI model can provide a reliable, high throughput means to study the effects of concussions in juvenile rats.