Investigating Gene-Diet Interactions Impacting the Association Between Macronutrient Intake and Glycemic Traits

Few studies have demonstrated reproducible gene-diet interactions (GDIs) impacting metabolic disease risk factors, likely due in part to measurement error in dietary intake estimation and insufficient capture of rare genetic variation. We aimed to identify GDIs across the genetic frequency spectrum impacting the macronutrient-glycemia relationship in genetically and culturally diverse cohorts. We analyzed 33,187 participants free of diabetes from 10 National Heart, Lung, and Blood Institute Trans-Omics for Precision Medicine program cohorts with whole-genome sequencing, self-reported diet, and glycemic trait data. We fit cohort-specific, multivariable-adjusted linear mixed models for the effect of diet, modeled as an isocaloric substitution of carbohydrate for fat, and its interactions with common and rare variants genome-wide. In main effect meta-analyses, participants consuming more carbohydrate had modestly lower glycemic trait values (e.g., for glycated hemoglobin [HbA1c], -0.013% HbA1c/250 kcal substitution). In GDI meta-analyses, a common African ancestry-enriched variant (rs79762542) reached study-wide significance and replicated in the UK Biobank cohort, indicating a negative carbohydrate-HbA1c association among major allele homozygotes only. Simulations revealed that >150,000 samples may be necessary to identify similar macronutrient GDIs under realistic assumptions about effect size and measurement error. These results generate hypotheses for further exploration of modifiable metabolic disease risk in additional cohorts with African ancestry.

ARTICLE HIGHLIGHTS

We aimed to identify genetic modifiers of the dietary macronutrient-glycemia relationship using whole-genome sequence data from 10 Trans-Omics for Precision Medicine program cohorts. Substitution models indicated a modest reduction in glycemia associated with an increase in dietary carbohydrate at the expense of fat. Genome-wide interaction analysis identified one African ancestry-enriched variant near the FRAS1 gene that may interact with macronutrient intake to influence hemoglobin A1c. Simulation-based power calculations accounting for measurement error suggested that substantially larger sample sizes may be necessary to discover further gene-macronutrient interactions.

Mechanism of iodine release from iodoapatite in aqueous solution

Incongruent release of iodine from iodoapatite (Pb₅(VO₄)₃I) for immobilization of¹²⁹iodine, controlled by exchange of iodide and hydroxide in solution.

Alkaliphilic Bacillus species show potential application in concrete crack repair by virtue of rapid spore production and germination then extracellular calcite formation

AIMS

Characterization of alkaliphilic Bacillus species for spore production and germination and calcite formation as a prelude to investigate their potential in microcrack remediation in concrete.

METHODS AND RESULTS

Conditions, extent and timing of endospore production was determined by dark-field light microscopy; germination induction and kinetics were assessed by combining reduction in optical density with formation of refractile bodies by phase-contrast microscopy. Bacillus pseudofirmus was selected from several species as the most suitable isolate. Levels and timing of calcium carbonate precipitated in vitro by B. pseudofirmus were evaluated by atomic absorption spectroscopy and structural identity confirmed as calcite and aragonite by Raman spectroscopy and FTIR. The isolate produced copious spores that germinated rapidly in the presence of germinants l-alanine, inosine and NaCl. Bacterial cells produced CaCO₃ crystals in microcracks and the resulting occlusion markedly restricted water ingress.

CONCLUSIONS

By virtue of rapid spore production and germination, calcium carbonate formation in vitro and in situ, leading to sealing of microcracks, B. pseudofirmus shows clear potential for remediation of concrete on a commercial scale.

SIGNIFICANCE AND IMPACT OF THE STUDY

Microbial sealing of microcracks should become a practicable and sustainable means of increasing concrete durability.

Randomised clinical trial: vercirnon, an oral CCR9 antagonist, vs. placebo as induction therapy in active Crohn's disease

BACKGROUND

Many patients with active Crohn's disease do not adequately respond to therapies, highlighting the need for new treatments.

AIMS

To conduct a randomised, double-blind, placebo-controlled phase 3 study to assess the efficacy and safety of vercirnon, an oral inhibitor of CC chemokine receptor-9, for the treatment of patients with moderately-to-severely active Crohn's disease.

METHODS

Patients with a Crohn's Disease Activity Index (CDAI) of 220-450, plus evidence of active disease (endoscopically confirmed or elevation of both C-reactive protein and faecal calprotectin), who had failed corticosteroid or immunosuppressant therapy were enrolled. Patients were equally randomised to receive placebo, vercirnon 500 mg once daily or vercirnon 500 mg twice daily. The primary endpoint was clinical response, defined as a 100-point decrease in CDAI from baseline to week 12.

RESULTS

Six hundred and eight patients were randomised. Patient characteristics and baseline demographics were similar among the groups. The proportions of patients achieving a clinical response were 25.1%, 27.6% and 27.2% for placebo, once daily and twice daily respectively; treatment differences were not significant (2.5%; 95% confidence interval, CI -6.1% to 11.0%, P = 0.546 for once daily vs. placebo, and 2.1%; 95% CI -6.5% to 10.7%, P = 0.648 for twice daily vs. placebo). Adverse events were reported in 69.8%, 73.3% and 78.1% with serious adverse events in 8.9%, 5.9%, and 6.0% of patients in the placebo, once-daily and twice-daily groups, respectively.

CONCLUSIONS

We did not demonstrate efficacy of vercirnon as an induction therapy in patients with moderately-to-severely active Crohn's disease; its effect in maintenance therapy was not addressed.

Collaborative study for the establishment of the WHO 3(rd) International Standard for Endotoxin, the Ph. Eur. endotoxin biological reference preparation batch 5 and the USP Reference Standard for Endotoxin Lot H0K354

An international collaborative study was organised jointly by the World Health Organization (WHO)/National Institute for Biological Standards and Control (NIBSC), the United States Pharmacopeia (USP) and the European Directorate for the Quality of Medicines & HealthCare (EDQM/Council of Europe) for the establishment of harmonised replacement endotoxin standards for these 3 organisations. Thirty-five laboratories worldwide, including Official Medicines Control Laboratories (OMCLs) and manufacturers enrolled in the study. Three candidate preparations (10/178, 10/190 and 10/196) were produced with the same material and same formulation as the current reference standards with the objective of generating a new (3(rd)) International Standard (IS) with the same potency (10 000 IU/vial) as the current (2(nd)) IS, as well as new European Pharmacopoeia (Ph. Eur.). and USP standards. The suitability of the candidate preparations to act as the reference standard in assays for endotoxin performed according to compendial methods was evaluated. Their potency was calibrated against the WHO 2(nd) IS for Endotoxin (94/580). Gelation and photometric methods produced similar results for each of the candidate preparations. The overall potency estimates for the 3 batches were comparable. Given the intrinsic assay precision, the observed differences between the batches may be considered unimportant for the intended use of these materials. Overall, these results were in line with those generated for the establishment of the current preparations of reference standards. Accelerated degradation testing of vials stored at elevated temperatures supported the long-term stability of the 3 candidate preparations. It was agreed between the 3 organisations that batch 10/178 be shared between WHO and EDQM and that batches 10/190 and 10/196 be allocated to USP, with a common assigned value of 10 000 IU/vial. This value maintains the continuity of the global harmonisation of reference materials and unitage for the testing of endotoxins in parenteral pharmaceutical products. Based on the results of the collaborative study, batch 10/178 was established by the European Pharmacopoeia Commission as the Ph. Eur. Endotoxin Biological Reference Preparation (BRP) batch 5. The same batch was also established by the Expert Committee on Biological Standardisation (ECBS) of WHO as the WHO 3(rd) IS for Endotoxin. Batch 10/190 was adopted as the USP Endotoxin Reference Standard, lot H0K354 and vials from this same batch (10/190) will serve as the United States Food and Drug Administration (USFDA) Endotoxin Standard, EC-7.

Factor VIII Bypassing Activity (FEIBA) assays: standardization and development of the 1st NIBSC Working Standard for FEIBA--results from a collaborative study

Factor-Eight-Inhibitor-Bypassing-Activity (FEIBA) is a bypassing-agent used to control spontaneous bleeding or cover surgical interventions in Haemophiliacs who develop neutralizing antibodies against FVIII/FIX. The market lot-release of FEIBA is dependent on specific clot-based assays, carried out by both the manufacturer and regulatory authorities, relative to manufacturer's in-house standards, which are produced on a small-scale and are replaced frequently. We sought to standardize the FEIBA assay by developing a FEIBA primary standard which would be internationally available in sufficiently large quantities, with a predicted lifetime of many years. A collaborative study involving the manufacturer and three regulatory authorities, was carried out in which a candidate material, sample B (06/172), was calibrated by assays relative to the manufacturer's in-house FEIBA standards (C and D). All laboratories used their routine validated methods (16 APTT-assays, 8 ACTIN-FS-assays and 27 DAPTTIN-assays). Intra-laboratory geometric coefficients of variation (GCVs) for candidate B ranged from 3% to 29% (GCVs <9% from majority of labs). Assessment of inter-laboratory variability gave overall GCV values of 6.9% and 4.4% relative to standards C and D, respectively, for all methods. There was good agreement in potency estimation between laboratories using each of the three methods, with the overall potencies by the three methods differing by less than 10% of the overall mean, giving an overall combined potency of 28.0 units per ampoule. All participants agreed that candidate B (06/172) be established as the 1st NIBSC Working Standard for FEIBA with an assigned potency of 28.0 units per ampoule, based on combined results for both methods, relative to either standard C or D.

Diabetes is associated with impairment of uterine contractility and high Caesarean section rate

AIMS/HYPOTHESIS

The prevalence of births worldwide complicated by diabetes mellitus is increasing. In the UK, for example, <25% of diabetic women have a non-instrumental vaginal delivery. Strikingly, more than half the Caesarean sections (CS) in these patients are non-elective, but the reasons for this are not understood. We have tested the hypothesis that poor myometrial contractility as a consequence of the disease contributes to this high CS rate.

METHODS

We compared spontaneous, high K depolarisation and oxytocin-induced contractions from diabetic and matched control patients having an elective CS. To investigate the mechanism of any differences we measured intracellular Ca, and performed western blotting and compared the tissues histologically.

RESULTS

There was significantly decreased contraction amplitude and duration in uteri from diabetic compared with control patients, even when possible confounders such as BMI were analysed. Reduced intracellular calcium signals and expression of calcium entry channels were found in uteruses from diabetic patients, which, along with a reduction in muscle content found on histological examination, could explain the reduced force. Myometrium from diabetic patients was responsive to oxytocin, but still did not reach the levels found in non-diabetic patients.

CONCLUSIONS/INTERPRETATIONS

These are the first data investigating myometrium in diabetic patients and they support the hypothesis that there is poorer contractility even in the presence of oxytocin. The underlying mechanism is related to reduced Ca channel expression and intracellular calcium signals and a decrease in muscle mass. We conclude that these factors significantly contribute to the increased emergency CS rate in diabetic patients.

An international collaborative study to establish a replacement World Health Organization International Standard for human immunodeficiency virus 1 RNA nucleic acid assays

BACKGROUND AND OBJECTIVES

An international collaborative study was undertaken to identify a replacement for the World Health Organization (WHO) 1st International Standard for human immunodeficiency virus 1 (HIV-1) RNA for use in nucleic acid-based techniques (NAT) (code 97/656). In the original study to establish the 1st International Standard, a second candidate material (code 97/650) had been shown to perform well and this was re-evaluated to establish whether it would be a suitable replacement.

MATERIALS AND METHODS

Eight laboratories from six different countries participated in the collaborative study to evaluate the candidate replacement standard. A total of eight different NATs were used, five in a quantitative format and three qualitative, of which five were commercially available.

RESULTS

The results showed that the estimates of RNA copies in the current study were generally in line with those of the original study and there was no evidence of any drift in overall levels expressed in International Units (IU) for the candidate standard between the two studies. Furthermore, it was shown to be stable over long-term storage at -20 degrees C.

CONCLUSIONS

The candidate material code 97/650 was established by the WHO as the 2nd International Standard for HIV-1 RNA for use in NAT and assigned a unitage of 5.56 log(10) (363 078) IU/vial.

Calibration of human coagulation factor VIII concentrate Ph. Eur. BRP Batch 4 for use in potency assays

The European Pharmacopoeia Biological Reference Preparation (Ph. Eur. BRP) Batch 4 was established as an international common working standard for potency determination of human coagulation factor VIII (FVIII) preparations to replace the dwindling stocks of the BRP Batch 3, the current European standard. Similarly, stocks of the current World Health Organisation 7th International Standard (WHO 7th IS) were also running low. Therefore a project was jointly organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe) and the National Institute for Biological Standards and Control (NIBSC, UK) in order to replace both standards concomitantly. The potency of the BRP Batch 4 was assigned during an international collaborative study involving 38 laboratories with reference to the WHO 7th IS and the BRP Batch 3. Four candidate materials, 2 plasma-derived (samples A and C) and 2 recombinant (samples B and D) have been evaluated, sample C being the specific candidate for the replacement of the BRP Batch 3. Participants were instructed to perform 8 independent assays following their own routine validated methods, by either the one-stage clotting assay or the chromogenic assay, or both. Laboratories returned 22 data sets for the clotting assay and 30 data sets for the chromogenic assay. This publication reports the results obtained with both assays but only the results of the chromogenic assay are highlighted in the conclusions, as it is the assay prescribed by the European Pharmacopoeia. Data were analysed separately for both assays. The consensus potency value was calculated as the unweighted geometric mean of the unweighted geometric means of each individual laboratory. For sample C, there was a significant difference in potency estimate between the chromogenic and the clotting assay. It was therefore not possible to reconcile both results. The chromogenic potencies however were in very good agreement being 10.4 IU/ampoule (n = 30), when assessed against both standards. The inter-laboratory geometric coefficient of variation (GCV) was 4.8 % and 7.1 % against the WHO 7th IS and the BRP Batch 3 respectively. The Ph. Eur. BRP Batch 4 is a freeze-dried, plasma-derived concentrate. The material was filled in approximately 20,000 ampoules and lyophilised. The final residual water content is 0.33 %. Based on accelerated degradation studies, the stability of the material is suitable for a reference preparation. The candidate Ph. Eur. BRP Batch 4 was adopted at the 136th session of the European Pharmacopoeia Commission in March 2010. The standard will be available from the EDQM with the catalogue number H0920000 upon exhaustion of the current batch.

Hemoperfusion with Amberlite resin in the treatment of self-poisoning

Ten patients with various intoxications were treated with resin hemoperfusion. Three of four patients with grade IV coma due to tricyclic antidepressant (TCA) poisoning could be extubated during or on termination of hemoperfusion. Clearance values of 135--185 and 190--200 ml/min were obtained for amitriptyline and nortriptyline, respectively. One patient with severe chloral hydrate poisoning could be extubated after less than one hour's hemoperfusion. A clearance of 140 ml/min was obtained in a uremic patient with AV block II due to digitoxin intoxication. Four patients with mushroom poisoning were treated with combined hemoperfusion-hemodialysis. A transient fall in platelet count was seen in all patients. Resin hemoperfusion is of definite value in selected, severe cases of self-poisoning with psychotropic drugs such as TCA and possibly in cases of mushroom poisoning where the prognosis with hemodialysis and supportive therapy is doubtful.

Self-poisoning treated in the ICU

This retrospective study compares number and type of self-poisonings admitted to the intensive care units (ICU) at Sahlgren's Hospital, Gothenburg, during 1972 and 1976. The total number of patients requiring intensive care was unchanged, but a change in the pattern of self-poisoning was seen. In 1976 the number of patients requiring intensive care following acute alcohol intoxication had increased, whereas the number of barbiturate and methaqualone poisonings decreased. Tricyclic antidepressants formed the largest group in both years. Fewer patients needed endotracheal intubation and IPPV in 1976 than in 1972. Also, fewer complications were seen, and the death rate among ICU-treated patients decreased. In the Gothenburg area barbiturates accounted for one half of all deaths due to self-poisoning and tricyclic antidepressants for one fifth. Any expected decrease in intensive care as a result of fewer barbiturate and methaqualone poisonings was obscured by an increase in severe alcohol intoxication.

Clinical aspects of tricyclic antidepressant poisoning

Self-poisoning with antidepressant drugs was studied retrospectively in 225 patients admitted to an intensive care unit. Amitriptyline accounted for the overwhelming majority of cases (70%); 106 patients (47%) had taken two or more drugs, in 81 patients (36%) ethanol was found in the blood. Four patients (2%) died. On admission, 111 patients (49%) were unconscious (grade III). A further 30 patients (13%) were in grade IV coma, and of these 27 had taken amitriptyline. Twenty-four hours after admission, 22 patients (10%) remained in coma. Thirty-six patients (16%) required assisted ventilation. Nineteen patients (8%) had convulsions and 6 (3%) aspired stomach contents. Sixty-one patients (27%) had a widened QRS interval exceeding 100 msec, 18 (30%) of them required assisted ventilation, 21 (34%) were in stage IV coma and 15 (25%) had convulsions. This relationship between a widened QRS interval and the severity of intoxication should be considered in the initial assessment of patients with tricyclic antidepressant poisoning.

Stable lyophilized reagents for the serum ferritin assay

Two monoclonal antibodies to human ferritin, including one that was coupled to horseradish peroxidase, were lyophilized. These reagents show little loss of activity on reconstitution and demonstrate acceptable stability in the accelerated degradation test. When applied in a simple ELISA for the assay of serum ferritin along with the WHO standard for serum ferritin (80/602) they provide a robust assay with standardized reagents which is potentially suitable for use as a reference assay.

Establishment of replacement batches for heparin low-molecular-mass for calibration CRS, and the International Standard Low Molecular Weight Heparin for Calibration

An international collaborative study involving fourteen laboratories has taken place, organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM) with National Institute for Biological Standards & Control (NIBSC) (in its capacity as a World Health Organisation (WHO) Laboratory for Biological Standardisation) to provide supporting data for the establishment of replacement batches of Heparin Low-Molecular-Mass (LMM) for Calibration Chemical Reference Substance (CRS), and of the International Reference Reagent (IRR) Low Molecular Weight Heparin for Molecular Weight Calibration. A batch of low-molecular-mass heparin was donated to the organisers and candidate preparations of freeze-dried heparin were produced at NIBSC and EDQM. The establishment study was organised in two phases: a prequalification (phase 1, performed in 3 laboratories in 2005) followed by an international collaborative study (phase 2). In phase 2, started in March 2006, molecular mass parameters were determined for seven different LMM heparin samples using the current CRS batch and two batches of candidate replacement material with a defined number average relative molecular mass (Mn) of 3,700, determined in phase 1. The values calculated using the candidates as standard were systematically different from values calculated using the current batch with its assigned number-average molecular mass (Mna) of 3,700. Using raw data supplied by participants, molecular mass parameters were recalculated using the candidates as standard with values for Mna of 3,800 and 3,900. Values for these parameters agreed more closely with those calculated using the current batch supporting the fact that the candidates, though similar to batch 1 in view of the production processes used, differ slightly in terms of molecular mass distribution. Therefore establishment of the candidates was recommended with an assigned Mna value of 3,800 that is both consistent with phase 1 results and guarantees continuity with the current CRS batch. In phase 2, participants also determined molecular weight parameters for the seven different LMM heparin samples using both the 1st IRR (90/686) and its Broad Standard Table and the candidate World Health Organization (WHO) 2nd International Standard (05/112) (2nd IS) using a Broad Standard Table established in phase 1. Mean molecular weights calculated using 2nd IS were slightly higher than with 1st IRR, and participants in the study indicated that this systematic difference precluded establishment of 2nd IS with the table supplied. A replacement Broad Standard Table has been devised on the basis of the central recalculations of raw data supplied by participants; this table gives improved agreement between values derived using the 1st IRR and the candidate 2nd IS. On the basis of this study a recommendation was made for the establishment of 2nd IS and its proposed Broad Standard Table as a replacement for the 1st International Reference Reagent Low Molecular Weight Heparin for Molecular Weight Calibration. Unlike the 1st IRR however, the candidate material 2nd IS is not suitable for use with the method of Nielsen. The candidate materials were established as heparin low-molecular-mass for calibration batches 2 and 3 by the Ph. Eur. Commission in March 2007 and as 2nd IS low-molecular-weight heparin for molecular weight calibration (05/112) by the Expert Committee on Biological Standardization in November 2007.

International collaborative study to establish immunoglobulin (anti-D test) BRP batch 1

An international collaborative study was organised to establish a European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) and United States (US) Food and Drug Administration (FDA) reference preparation for the test for anti-D (anti-Rho) antibodies in human normal immunoglobulin for intravenous administration (IGIV). A candidate positive control (IGIV+anti-D) and negative control IGIV were compared to corresponding World Health Organization (WHO) International Reference Reagents using a direct haemagglutination reference method. Sixteen (16) laboratories participated in the collaborative study. Further to completion of the study, the materials assayed in the study were granted the status of Ph. Eur. and US FDA reference preparations for controlling the levels of anti-D in IGIV.

A World Health Organization International Standard for hepatitis A virus RNA nucleic acid amplification technology assays

BACKGROUND AND OBJECTIVES

Sixteen laboratories from 10 different countries participated in an international collaborative study to evaluate candidate materials as the first World Health Organization (WHO) International Standard for hepatitis A virus (HAV) RNA nucleic acid amplification technology (NAT) assays.

MATERIALS AND METHODS

Five candidate materials were analysed in this study: materials AA and BB were lyophilized, while materials CC, DD and EE were liquid preparations. Samples were diluted in pooled plasma or in pooled cryo-poor plasma (sample EE). Serial dilutions of the candidate materials were tested by each laboratory in four independent assays and the results were analysed statistically.

RESULTS

The mean log(10)'equivalents' per ml were 5.29 for sample AA, 5.07 for sample BB, 4.99 for sample CC, 5.40 for sample DD and 4.08 for sample EE.

CONCLUSIONS

Based on the results of this study, sample AA was established as the first International Standard for HAV RNA NAT assays at the WHO Expert Committee on Biological Standardizaton (ECBS) meeting held in February 2003. The code number of this preparation is 00/560 and the potency, based on the study, is 100 000 International Units (IU)/ml.