Bone-anchored prostheses for lower limb amputation in a French cohort with 1-15 years of follow-up: implant survival rates, mechanical complications, and reported outcomes.

PURPOSE: To evaluate the implant survival rate, mechanical complications, and reported patient outcomes of bone-anchored prostheses for patients with lower limb amputation in France after 1-15 years of follow-up. METHODS: This retrospective cohort study included patients who underwent surgery at a single center in France between 2007 and 2021. The primary outcomes were the implant survival rate and functional scores assessed by the Questionnaire for Transfemoral Amputees (Q-TFA). Secondary outcomes were adverse events that occurred during follow-up. RESULTS: The cohort consisted of 20 bone-anchored prostheses in 17 patients. The main level of amputation was transfemoral (82%, n = 14). The main reason for amputation was trauma (n = 15). The mean age at amputation was 32 (range 15-54) years, and the mean age at the first stage of osseointegration was 41 (range 21-58) years. The Kaplan-Meier survival curve showed respective survival rates of 90%, 70%, and 60% at 2, 10, and 15 years. All Q-TFA scores were significantly improved at last the follow-up. Eleven patients (65%) experienced mechanical complications. In total, 37 infectious events occurred in 13 patients (76%), mainly comprising stage 1 infections (68%, n = 25). Only two cases of septic loosening occurred (12%), leading to implant removal. CONCLUSION: This is the first French cohort of bone-anchored prostheses and among the series with the longest follow-up periods. The findings indicate that bone-anchored prostheses are safe and reliable for amputee patients who have difficulties with classic prostheses.

Three-Dimensional Collagen Topology Shapes Cell Morphology, beyond Stiffness.

Cellular heterogeneity is associated with many physiological processes, including pathological ones, such as morphogenesis and tumorigenesis. The extracellular matrix (ECM) is a key player in the generation of cellular heterogeneity. Advances in our understanding rely on our ability to provide relevant in vitro models. This requires obtainment of the characteristics of the tissues that are essential for controlling cell fate. To do this, we must consider the diversity of tissues, the diversity of physiological contexts, and the constant remodeling of the ECM along these processes. To this aim, we have fabricated a library of ECM models for reproducing the scaffold of connective tissues and the basement membrane by using different biofabrication routes based on the electrospinning and drop casting of biopolymers from the ECM. Using a combination of electron microscopy, multiphoton imaging, and AFM nanoindentation, we show that we can vary independently protein composition, topology, and stiffness of ECM models. This in turns allows one to generate the in vivo complexity of the phenotypic landscape of ovarian cancer cells. We show that, while this phenotypic shift cannot be directly correlated with a unique ECM feature, the three-dimensional collagen fibril topology patterns cell shape, beyond protein composition and stiffness of the ECM. On this line, this work is a further step toward the development of ECM models recapitulating the constantly remodeled environment that cells face and thus provides new insights for cancer model engineering and drug testing.

A High-Throughput Platform for Culture and 3D Imaging of Organoids.

The characterization of a large number of three-dimensional (3D) organotypic cultures (organoids) at different resolution scales is currently limited by standard imaging approaches. This protocol describes a way to prepare microfabricated organoid culture chips, which enable multiscale, 3D live imaging on a user-friendly instrument requiring minimal manipulations and capable of up to 300 organoids/h imaging throughput. These culture chips are compatible with both air and immersion objectives (air, water, oil, and silicone) and a wide range of common microscopes (e.g., spinning disk, point scanner confocal, wide field, and brightfield). Moreover, they can be used with light-sheet modalities such as the single-objective, single-plane illumination microscopy (SPIM) technology (soSPIM). The protocol described here gives detailed steps for the preparation of the microfabricated culture chips and the culture and staining of organoids. Only a short length of time is required to become familiar with, and consumables and equipment can be easily found in normal biolabs. Here, the 3D imaging capabilities will be demonstrated only with commercial standard microscopes (e.g., spinning disk for 3D reconstruction and wide field microscopy for routine monitoring).

Minty aroma compounds in red wine: Development of a novel automated HS-SPME-arrow and gas chromatography-tandem mass spectrometry quantification method.

A novel automated method was developed for the quantitative determination of nine terpenoids that could contribute to the minty notes of red wine bouquet. The method couples headspace SPME-Arrow extraction with GC-MS/MS analysis. PDMS/DVB fiber was chosen for the extraction and an ionization energy of 30 eV permitted to optimize the analyte detection. The optimal sample preparation consists of a two-fold dilution of the wine sample with addition of 4 g of sodium chloride while the most suitable extraction conditions take place at 50 °C for 1 h. The method shows good linearity, intraday variations between 2 and 25%, interday variations between 7 and 23% and recoveries between 80 and 119%. The method exhibits the required low detection (between 3 and 60 ng/L) and quantification (between 6 ng/L and 200 ng/L) limits. These limits have permitted the quantification of the pool of minty terpenoids in fourteen red Bordeaux wines.

Microvascular maturation by mesenchymal stem cells in vitro improves blood perfusion in implanted tissue constructs.

Blood perfusion of grafted tissue constructs is a hindrance to the success of stem cell-based therapies by limiting cell survival and tissue regeneration. Implantation of a pre-vascularized network engineered in vitro has thus emerged as a promising strategy for promoting blood supply deep into the construct, relying on inosculation with the host vasculature. We aimed to fabricate in vitro tissue constructs with mature microvascular networks, displaying perivascular recruitment and basement membrane, taking advantage of the angiogenic properties of dental pulp stem cells and self-assembly of endothelial cells into capillaries. Using digital scanned light-sheet microscopy, we characterized the generation of dense microvascular networks in collagen hydrogels and established parameters for quantification of perivascular recruitment. We also performed original time-lapse analysis of stem cell recruitment. These experiments demonstrated that perivascular recruitment of dental pulp stem cells is driven by PDGF-BB. Recruited stem cells participated in deposition of vascular basement membrane and vessel maturation. Mature microvascular networks thus generated were then compared to those lacking perivascular coverage generated using stem cell conditioned medium. Implantation in athymic nude mice demonstrated that in vitro maturation of microvascular networks improved blood perfusion and cell survival within the construct. Taken together, these data demonstrate the strong potential of in vitro production of mature microvasculature for improving cell-based therapies.

Native Collagen: Electrospinning of Pure, Cross-Linker-Free, Self-Supported Membrane.

Rebuilding biological environments is crucial when facing the challenges of fundamental and biomedical research. Thus, preserving the native state of biomolecules is essential. We use electrospinning (ES), which is an extremely promising method for the preparation of fibrillar membranes to mimic the ECM of native tissues. Here, we report for the first time (1) the ES of pure and native collagen into a self-supported membrane in absence of cross-linker and polymer support, (2) the preservation of the membrane integrity in hydrated media in absence of cross-linker, and (3) the preservation of the native molecular structure and recovery of the hierarchical assembly of collagen. We use a multiscale approach to characterize collagen native structure at the molecular level using circular dichroism, and to investigate collagen hierarchical organization within the self-supported membrane using a combination of multiphoton and electron microscopies. Finally, we show that the membranes are perfectly suited for cell adhesion and spreading, making them very promising candidates for the development of biomaterials and finding applications in biomedical research.

Scavenger Receptor Cysteine-Rich domains of Lysyl Oxidase-Like2 regulate endothelial ECM and angiogenesis through non-catalytic scaffolding mechanisms.

Lysyl oxidases are major actors of microenvironment and extracellular matrix (ECM) remodeling. These cross-linking enzymes are thus involved in many aspects of physiopathology, including tumor progression, fibrosis and cardiovascular diseases. We have already shown that Lysyl Oxidase-Like 2 (LOXL2) regulates collagen IV deposition by endothelial cells and angiogenesis. We here provide evidence that LOXL2 also affects deposition of other ECM components, including fibronectin, thus altering structural and mechanical properties of the matrix generated by endothelial cells. LOXL2 interacts intracellularly and directly with collagen IV and fibronectin before incorporation into ECM fibrillar structures upon exocytosis, as demonstrated by TIRF time-lapse microscopy. Furthermore, surface plasmon resonance experiments using recombinant scavenger receptor cysteine-rich (SRCR) domains truncated for the catalytic domain demonstrated their direct binding to collagen IV. We thus used directed mutagenesis to investigate the role of LOXL2 catalytic domain. Neither enzyme activity nor catalytic domain were necessary for collagen IV deposition and angiogenesis, whereas the SRCR domains were effective for these processes. Finally, surface coating with recombinant SRCR domains restored deposition of collagen IV by LOXL2-depleted cells. We thus propose that LOXL2 SRCR domains orchestrate scaffolding of the vascular basement membrane and angiogenesis through interactions with collagen IV and fibronectin, independently of the enzymatic cross-linking activity.

Phostine 3.1a as a pharmacological compound with antiangiogenic properties against diseases with excess vascularization.

Angiogenesis is a complex process leading to the growth of new blood vessels from existing vasculature, triggered by local proangiogenic factors such as VEGF. An excess of angiogenesis is a recurrent feature of various pathologic conditions such as tumor growth. Phostines are a family of synthetic glycomimetic compounds that exhibit anticancer properties, and the lead compound 3-hydroxy-4,5-bis-benzyloxy-6-benzyloxymethyl-2-phenyl2-oxo-2λ5-[1,2]oxaphosphinane (PST 3.1a) shows antiglioblastoma properties both in vitro and in vivo. In the present study, we assessed the effect of PST 3.1a on angiogenesis and endothelial metabolism. In vitro, PST 3.1a (10 µM) inhibited all steps that regulate angiogenesis, including migration, proliferation, adhesion, and tube formation. In vivo, PST 3.1a reduced intersegmental vessel formation and vascularization of the subintestinal plexus in zebrafish embryos and also altered pathologic angiogenesis and glioblastoma progression in vivo. Mechanistically, PST 3.1a altered interaction of VEGF receptor 2 and glycosylation-regulating protein galectin-1, a key component regulating angiogenesis associated with tumor resistance. Thus, these data show that use of PST 3.1a is an innovative approach to target angiogenesis.-Bousseau, S., Marchand, M., Soleti, R., Vergori, L., Hilairet, G., Recoquillon, S., Le Mao, M., Gueguen, N., Khiati, S., Clarion, L., Bakalara, N., Martinez, M. C., Germain, S., Lenaers, G., Andriantsitohaina, R. Phostine 3.1a as a pharmacological compound with antiangiogenic properties against diseases with excess vascularization.

Lysyl oxidase-like 2 (LOXL2)-mediated cross-linking of tropoelastin.

Lysyl oxidases (LOXs) play a central role in extracellular matrix remodeling during development and tumor growth and fibrosis through cross-linking of collagens and elastin. We have limited knowledge of the structure and substrate specificity of these secreted enzymes. LOXs share a conserved C-terminal catalytic domain but differ in their N-terminal region, which is composed of 4 repeats of scavenger receptor cysteine-rich (SRCR) domains in LOX-like (LOXL) 2. We investigated by X-ray scattering and electron microscopy the low-resolution structure of the full-length enzyme and the structure of a shorter form lacking the catalytic domain. Our data demonstrate that LOXL2 has a rod-like structure with a stalk composed of the SRCR domains and the catalytic domain at its tip. We detected direct interaction between LOXL2 and tropoelastin (TE) and also LOXL2-mediated deamination of TE. Using proteomics, we identified several allysines together with cross-linked TE peptides. The elastin-like material generated was resistant to trypsin proteolysis and displayed mechanical properties similar to mature elastin. Finally, we detected the codistribution of LOXL2 and elastin in the vascular wall. Altogether, these data suggest that LOXL2 could participate in elastogenesis in vivo and could be used as a means of cross-linking TE in vitro for biomimetic and cell-compatible tissue engineering purposes.-Schmelzer, C. E. H., Heinz, A., Troilo, H., Lockhart-Cairns, M.-P., Jowitt, T. A., Marchand, M. F., Bidault, L., Bignon, M., Hedtke, T., Barret, A., McConnell, J. C., Sherratt, M. J., Germain, S., Hulmes, D. J. S., Baldock, C., Muller, L. Lysyl oxidase-like 2 (LOXL2)-mediated cross-linking of tropoelastin.

Extracellular matrix scaffolding in angiogenesis and capillary homeostasis.

The extracellular matrix (ECM) of blood vessels, which is composed of both the vascular basement membrane (BM) and the interstitial ECM is identified as a crucial component of the vasculature. We here focus on the unique molecular composition and scaffolding of the capillary ECM, which provides structural support to blood vessels and regulates properties of endothelial cells and pericytes. The major components of the BM are collagen IV, laminins, heparan sulfate proteoglycans and nidogen and also associated proteins such as collagen XVIII and fibronectin. Their organization and scaffolding in the BM is required for proper capillary morphogenesis and maintenance of vascular homeostasis. The BM also regulates vascular mechanosensing. A better understanding of the mechanical and structural properties of the vascular BM and interstitial ECM therefore opens new perspectives to control physiological and pathological angiogenesis and vascular homeostasis. The overall aim of this review is to explain how ECM scaffolding influences angiogenesis and capillary integrity.

No Robust Evidence of Future Changes in Major Stratospheric Sudden Warmings: A Multi-model Assessment from CCMI.

Major stratospheric sudden warmings (SSWs) are the largest instance of wintertime variability in the Arctic stratosphere. Due to their relevance for the troposphere-stratosphere system, several previous studies have focused on their potential response to anthropogenic forcings. However, a wide range of results have been reported, from a future increase in the frequency of SSWs to a decrease. Several factors might explain these contradictory results, notably the use of different metrics for the identification of SSWs, and the impact of large climatological biases in single-model studies. Here we revisit the question of future SSWs changes, using an identical set of metrics applied consistently across 12 different models participating in the Chemistry Climate Model Initiative. From analyzing future integrations we find no statistically significant change in the frequency of SSWs over the 21st century, irrespective of the metric used for the identification of SSWs. Changes in other SSWs characteristics, such as their duration and the tropospheric forcing, are also assessed: again, we find no evidence of future changes over the 21st century.

Matrix-Applied Characterized Autologous Cultured Chondrocytes Versus Microfracture: Two-Year Follow-up of a Prospective Randomized Trial.

BACKGROUND: Randomized controlled trials studying the efficacy and safety of matrix-applied characterized autologous cultured chondrocytes (MACI) versus microfracture (MFX) for treating cartilage defects are limited. PURPOSE: To compare the clinical efficacy and safety of MACI versus MFX in the treatment of patients with symptomatic cartilage defects of the knee. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: Patients enrolled in the SUMMIT (Demonstrate the Superiority of MACI implant to Microfracture Treatment) trial had ≥1 symptomatic focal cartilage defect (Outerbridge grade III or IV; ≥3 cm(2)) of the femoral condyles or trochlea, with a baseline Knee Injury and Osteoarthritis Outcome Score (KOOS) pain value <55. The co-primary efficacy endpoint was the change in the KOOS pain and function subscores from baseline to 2 years. Histological evaluation and magnetic resonance imaging (MRI) assessments of structural repair tissue, treatment failure, the remaining 3 KOOS subscales, and safety were also assessed. RESULTS: Of the 144 patients treated, 137 (95%) completed the 2-year assessment. Patients had a mean age of 33.8 years and a mean lesion size of 4.8 cm(2). The mean KOOS pain and function subscores from baseline to 2 years were significantly more improved with MACI than with MFX (pain: MACI, 37.0 to 82.5 vs MFX, 35.5 to 70.9; function: MACI, 14.9 to 60.9 vs MFX, 12.6 to 48.7; P = .001). A significant improvement in scores was also observed on the KOOS subscales of activities of daily living (MACI, 43.5 to 87.2 vs MFX, 42.6 to 75.8; P < .001), knee-related quality of life (MACI, 18.8 to 56.2 vs MFX, 17.2 to 47.3; P = .029), and other symptoms (MACI, 48.3 to 83.7 vs MFX, 44.4 to 72.2; P < .001) for patients treated with MACI compared with MFX. Repair tissue quality was good as assessed by histology/MRI, but no difference was shown between treatments. A low number of treatment failures (nonresponders: MACI, 12.5% vs MFX, 31.9%; P = .016) and no unexpected safety findings were reported. CONCLUSION: The treatment of symptomatic cartilage knee defects ≥3 cm(2) in size using MACI was clinically and statistically significantly better than with MFX, with similar structural repair tissue and safety, in this heterogeneous patient population. Moreover, MACI offers a more efficacious alternative than MFX with a similar safety profile for the treatment of symptomatic articular cartilage defects of the knee.

Quantitative solid phase microextraction--gas chromatography mass spectrometry analysis of five megastigmatrienone isomers in aged wine.

Megastigmatrienone is a key flavor compound in tobacco. It has also been detected in wine, where it may contribute to a tobacco/incense aroma, but its importance and concentration in wines had never previously been evaluated. A method was developed and validated for quantifying the five megastigmatrienone isomers in red and white wines. Megastigmatrienone isomers were extracted by headspace solid-phase microextraction (HS-SPME), with a 65 µm film thickness polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber and analyzed using gas chromatography-mass spectrometry (GC/MS) in selected ion monitoring mode (SIM). Several parameters affecting the length of the adsorption process (i.e., adding salt, extraction time and extraction temperature) were tested. The optimum analytical conditions were established. The LOQ were between 0.06 µg L(-1) and 0.49 µg L(-1) for white wine and 0.11 µg L(-1) and 0.98 µg L(-1) for red wine, repeatability in both types of wine was less than 10% and recovery ranged from 96% for white wine to 94% for red wine. The five isomers of megastigmatrienone were quantified in red and white wines for the first time. Concentrations ranged from 2 µg L(-1) to 41 µg L(-1) in both red and white wines. Initial results revealed a link between wine aging and megastigmatrienone levels, indicating that megastigmatrienone may be a component in wine "bouquet".

Centrifugal partition chromatography applied to the isolation of oak wood aroma precursors.

Flavours extracted from oak wood during barrel ageing contribute to the organoleptic character of wines and spirits. The aim of this work was to identify the glycosidic precursors of the key volatile compounds responsible for oak wood aroma. Oak extract is a very complex matrix and, furthermore, precursors are present in very small quantities. Preparative centrifugal partition chromatography (CPC) is a promising solution for purifying the oak extract. The solvent system was selected on the basis of the partition coefficient of glycosidase enzyme activity (Kca). Thanks to the efficacy of CPC separation, three glucoside gallates were subsequently isolated by HPLC chromatography. Vanillin-(6'-O-galloyl)-O-ß-D-glucopyranoside, 3,4,5-trimethoxyphenyl-(6'-O-galloyl)-O-ß-D-glucopyranoside, and (6R,9R)-3-oxo-α-ionol-9-O-(6'-O-galloyl)-ß-glucopyranoside (macarangioside E) were isolated and identified. This was the first time that vanillin-(6'-O-galloyl)-O-ß-D-glucopyranoside was identified and the first time that macarangioside E was isolated from oak wood. Heating macarangioside E resulted in the formation of megastigmatrienone, which has an aroma reminiscent of tobacco.

Loss-of-function mutations in MC4R are very rare in the Greek severely obese adult population.

Melanocortin-4 receptor (MC4R) loss-of-function mutations are the commonest genetic cause of human monogenic obesity, so far. The contribution of MC4R coding mutations to severe obesity in the high-obesity prone Greek population has not been investigated to date. We determined the MC4R coding sequence of 510 obese and 469 lean control subjects of Greek origin, and we estimated the prevalence and the penetrance on obesity of MC4R loss-of-function mutations. The functional impact of novel nonsynonymous variants detected was investigated in vitro. We found two novel synonymous mutations (L23L and I102I), four nonsynonymous mutations (T112M, S127L, N274S, and S295L), and two polymorphisms (V103I and I251L) previously described in literature. We also detected a novel mutation (L207V) in a severely obese 69-year-old female patient, although the mutation did not cosegregate with obesity in the corresponding pedigree and had no functional consequences on MC4R protein function. Loss-of-function mutations represented 75% of all nonsynonymous rare mutations identified among lean carriers and only 25% among obese subjects (P = 0.0001). The prevalence of loss-of-function mutations was lower in the obese group than in lean control subjects (0.20 vs. 0.64%) but this difference was not significant. Therefore, the estimated penetrance of deleterious MC4R mutations was very low (6.3%) in heterozygous Greek carriers of MC4R loss-of-function mutations. Our data suggest that MC4R loss-of-function mutations are rare in the Greek population. MC4R genetic deficiency is unlikely to explain the high propensity to develop severe obesity in this specific population.

TCF7L2 splice variants have distinct effects on beta-cell turnover and function.

Type 2 diabetes manifests when the ß-cell fails to secrete sufficient amounts of insulin to maintain normoglycemia and undergoes apoptosis. The disease progression results from an interplay of environmental factors and genetic predisposition. Polymorphisms in T-cell factor 7-like 2 (TCF7L2) strongly correlate with type 2 diabetes mellitus (T2DM). While TCF7L2 mRNA is upregulated in islets in diabetes, protein levels are downregulated. The loss of TCF7L2 induces impaired function and apoptosis. By analyzing human isolated islets, we provide three explanations for this opposite regulation and the mechanisms of TCF7L2 on ß-cell function and survival. (i) We found TCF7L2 transcripts in the human ß-cell, which had opposite effects on ß-cell survival, function and Wnt signaling activation. While TCF7L2 clone B1, which lacks exons 13, 14, 15 and 16 induced ß-cell apoptosis, impaired function and inhibited glucagon-like peptide 1 response and downstream targets of Wnt signaling, clones B3 and B7 which both contain exon 13, improved ß-cell survival and function and activated Wnt signaling. (ii) TCF7L2 mRNA is extremely unstable and is rapidly degraded under pro-diabetic conditions and (iii) TCF7L2 depletion in islets induced activation of glycogen synthase kinase 3-ß, but this was independent of endoplasmic reticulum stress. We demonstrated function-specific transcripts of TCF7L2, which possessed distinct physiological and pathophysiological effects on the ß-cell. The presence of deleterious TCF7L2 splice variants may be a mechanism of ß-cell failure in T2DM.

Genetic and functional assessment of the role of the rs13431652-A and rs573225-A alleles in the G6PC2 promoter that are strongly associated with elevated fasting glucose levels.

OBJECTIVE: Genome-wide association studies have identified a single nucleotide polymorphism (SNP), rs560887, located in a G6PC2 intron that is highly correlated with variations in fasting plasma glucose (FPG). G6PC2 encodes an islet-specific glucose-6-phosphatase catalytic subunit. This study examines the contribution of two G6PC2 promoter SNPs, rs13431652 and rs573225, to the association signal. RESEARCH DESIGN AND METHODS: We genotyped 9,532 normal FPG participants (FPG <6.1 mmol/l) for three G6PC2 SNPs, rs13431652 (distal promoter), rs573225 (proximal promoter), rs560887 (3rd intron). We used regression analyses adjusted for age, sex, and BMI to assess the association with FPG and haplotype analyses to assess comparative SNP contributions. Fusion gene and gel retardation analyses characterized the effect of rs13431652 and rs573225 on G6PC2 promoter activity and transcription factor binding. RESULTS: Genetic analyses provide evidence for a strong contribution of the promoter SNPs to FPG variability at the G6PC2 locus (rs13431652: ß = 0.075, P = 3.6 × 10(-35); rs573225 ß = 0.073 P = 3.6 × 10(-34)), in addition to rs560887 (ß = 0.071, P = 1.2 × 10(-31)). The rs13431652-A and rs573225-A alleles promote increased NF-Y and Foxa2 binding, respectively. The rs13431652-A allele is associated with increased FPG and elevated promoter activity, consistent with the function of G6PC2 in pancreatic islets. In contrast, the rs573225-A allele is associated with elevated FPG but reduced promoter activity. CONCLUSIONS: Genetic and in situ functional data support a potential role for rs13431652, but not rs573225, as a causative SNP linking G6PC2 to variations in FPG, though a causative role for rs573225 in vivo cannot be ruled out.

G-allele of intronic rs10830963 in MTNR1B confers increased risk of impaired fasting glycemia and type 2 diabetes through an impaired glucose-stimulated insulin release: studies involving 19,605 Europeans.

OBJECTIVE: Genome-wide association studies have identified several variants within the MTNR1B locus that are associated with fasting plasma glucose (FPG) and type 2 diabetes. We refined the association signal by direct genotyping and examined for associations of the variant displaying the most independent effect on FPG with isolated impaired fasting glycemia (i-IFG), isolated impaired glucose tolerance (i-IGT), type 2 diabetes, and measures of insulin release and peripheral and hepatic insulin sensitivity. RESEARCH DESIGN AND METHODS: We examined European-descent participants in the Inter99 study (n = 5,553), in a sample of young healthy Danes (n = 372), in Danish twins (n = 77 elderly and n = 97 young), in additional Danish type 2 diabetic patients (n = 1,626) and control subjects (n = 505), in the Data from the Epidemiological Study on the Insulin Resistance Syndrome (DESIR) study (n = 4,656), in the North Finland Birth Cohort 86 (n = 5,258), and in the Haguenau study (n = 1,461). RESULTS: The MTNR1B intronic variant, rs10830963, carried most of the effect on FPG and showed the strongest association with FPG (combined P = 5.3 x 10(-31)) and type 2 diabetes. The rs10830963 G-allele increased the risk of i-IFG (odds ratio [OR] 1.64, P = 5.5 x 10(-11)) but not i-IGT. The G-allele was associated with a decreased insulin release after oral and intravenous glucose challenges (P < 0.01) but not after injection of tolbutamide. In elderly twins, the G-allele associated with hepatic insulin resistance (P = 0.017). CONCLUSIONS: The G-allele of MTNR1B rs10830963 increases risk of type 2 diabetes through a state of i-IFG and not through i-IGT. The same allele associates with estimates of beta-cell dysfunction and hepatic insulin resistance.

Smallness for gestational age interacts with high mobility group A2 gene genetic variation to modulate height.

OBJECTIVE: Height variability is largely under genetic control, although identifying the genetic variants involved has been until recently challenging. Smallness for gestational age (SGA) is a risk factor for adult short stature. Genome-wide association studies have identified a single nucleotide polymorphism (SNP) (rs1042725) in the high mobility group A2 gene (HMGA2) that consistently associates with height variability but its interaction with SGA is unknown. DESIGN: We assess the contribution of rs1042725 SNP and height variability in a French population and the impact of rs1042725 on SGA status at birth and height at adulthood in SGA individuals. METHODS: We genotyped rs1042725 in 4710 healthy participants from the Data from an Epidemiological Study on the Insulin Resistance syndrome (DESIR) cohort, 743 normal birth weight and 660 SGA individuals from the Haguenau study. RESULTS: rs1042725 is associated with increased height in the cohort participants (0.36 cm 95% CI (0.12-0.61) per C allele, P=0.004) but not with the SGA status or birth length. Interestingly, rs1042725 had a stronger effect on height in SGA participants (0.94 cm 95% CI (0.24-1.64) per C allele, P=0.009), especially in men (1.45 cm 95% CI (0.44-2.46) per C allele, P=0.005) in whom rs1042725 may explain 3% of height variability. SGA men carrying at least one C allele copy experienced more frequent catch-up in height (P(add)=0.07; P(dom)=0.03). CONCLUSIONS: Our study supports further the contribution of HMGA2 rs1042725 to height variability in European populations and shows an increased effect on height in SGA individuals where this variant favors height catch-up.

A variant near MTNR1B is associated with increased fasting plasma glucose levels and type 2 diabetes risk.

In genome-wide association (GWA) data from 2,151 nondiabetic French subjects, we identified rs1387153, near MTNR1B (which encodes the melatonin receptor 2 (MT2)), as a modulator of fasting plasma glucose (FPG; P = 1.3 x 10(-7)). In European populations, the rs1387153 T allele is associated with increased FPG (beta = 0.06 mmol/l, P = 7.6 x 10(-29), N = 16,094), type 2 diabetes (T2D) risk (odds ratio (OR) = 1.15, 95% CI = 1.08-1.22, P = 6.3 x 10(-5), cases N = 6,332) and risk of developing hyperglycemia or diabetes over a 9-year period (hazard ratio (HR) = 1.20, 95% CI = 1.06-1.36, P = 0.005, incident cases N = 515). RT-PCR analyses confirm the presence of MT2 transcripts in neural tissues and show MT2 expression in human pancreatic islets and beta cells. Our data suggest a possible link between circadian rhythm regulation and glucose homeostasis through the melatonin signaling pathway.