Systematic evaluation of validated type 2 diabetes and glycaemic trait loci for association with insulin clearance

AIMS/HYPOTHESIS

Insulin clearance is a highly heritable trait, for which few quantitative trait loci have been discovered. We sought to determine whether validated type 2 diabetes and/or glycaemic trait loci are associated with insulin clearance.

METHODS

Hyperinsulinaemic-euglycaemic clamps were performed in two Hispanic-American family cohorts totalling 1329 participants in 329 families. The Metabochip was used to fine-map about 50 previously identified loci for type 2 diabetes, fasting glucose, fasting insulin, 2 h glucose or HbA1c. This resulted in 17,930 variants, which were tested for association with clamp-derived insulin clearance via meta-analysis of the two cohorts.

RESULTS

In the meta-analysis, 38 variants located within seven loci demonstrated association with insulin clearance (p < 0.001). The top signals for each locus were rs10241087 (DGKB/TMEM195 [TMEM195 also known as AGMO]) (p = 4.4 × 10(-5)); chr1:217605433 (LYPLAL1) (p = 3.25 × 10(-4)); rs2380949 (GLIS3) (p = 3.4 × 10(-4)); rs55903902 (FADS1) (p = 5.6 × 10(-4)); rs849334 (JAZF1) (p = 6.4 × 10(-4)); rs35749 (IGF1) (p = 6.7 × 10(-4)); and rs9460557 (CDKAL1) (p = 6.8 × 10(-4)).

CONCLUSIONS/INTERPRETATION

While the majority of validated loci for type 2 diabetes and related traits do not appear to influence insulin clearance in Hispanics, several of these loci do show evidence of association with this trait. It is therefore possible that these loci could have pleiotropic effects on insulin secretion, insulin sensitivity and insulin clearance.

Effects of dietary factors on selenium levels of children to prevent Kashin-Beck disease during a high-prevalence period in an endemic area: a cohort study

Selenium (Se) supplements have been used to control Kashin-Beck disease (KBD) for decades, but the effect of diet without Se supplements is unclear because the prevalence of KBD has decreased. This matched cohort study was undertaken to determine dietary factors affecting selenium nutrition status of children living in KBD areas and the effects of Se supplements in preventing KBD. A total of 593 children aged 5-12 years were randomly selected during the high prevalence period of KBD from 1992 to 1995. Children in one village received Se supplemented (Se+) salt and were matched with three children in 16 other villages who did not receive Se supplemented (Se-) salt. A questionnaire and determinations of occipital hair Se to reflect body Se status were obtained at baseline (April 1992), at 6 months (October 1992), and yearly each April through 1995. Hair Se content in the Se+ group was significantly higher than in the Se- group (P < 0.001) at all time-points and was significantly related to the incidence of suspected KBD symptoms (P = 0.018). Four dietary factors significantly affected hair Se contents. Se levels were increased by consumption of Se+ salt (P < 0.001) and eating meat/egg often (P = 0.019) or occasionally (P = 0.001). Se levels were decreased by consumption of grain mildewed at harvest or in storage (P < 0.001 for each) and drinking ditch, river, or cellar water (P < 0.001; P = 0.002; P < 0.001, respectively). These results show that Se+ salt had a significant effect in maintaining the Se nutrition status of children in this cohort study but that dietary factors in those without Se supplements contributed as well.

Prevalence of cardiovascular disease and risk factors in the Chinese population with impaired glucose regulation: the 2007-2008 China national diabetes and metabolic disorders study

Cardiovascular disease (CVD) is one of the most common chronic diseases in China. This aim of this study is to determine the prevalence of CVDs and risk factors in Chinese impaired glucose regulation subjects.We used a multistage, stratified sampling method to select subjects from the general Chinese population aged 20 years and older. Subjects underwent an oral glucose tolerance test to identify normal glucose tolerance (NGT) and impaired glucose regulation including isolated impaired fasting glucose (i-IFG), impaired glucose tolerance (i-IGT), and combined IFG/IGT and diabetic mellitus (DM). A logistic regression analysis was performed to examine the association between glucose abnormalities and CVD events.We identified that 34 293 subjects had NGT, 1 469 i-IFG, 4 571 i-IGT, 957 IFG/IGT and 4 949 DM. The age-sex standardized prevalence rate of cardiovascular disease was 1.06% (95% CI 0.87-1.28), 1.79% (95% CI 1.37-2.33) and 3.83% (95% CI 2.79-5.24) in NGT, impaired glucose regulation and DM, respectively. Among impaired glucose subjects, prevalence of defined CVD risk factors (smoking, overweight, obesity, hypertension and dyslipidemia) was 29.52% (95% CI: 27.8-31.21), 36.25% (95% CI: 34.29-38.26), 10.05% (95% CI: 8.86-11.37), 36.43% (95% CI: 34.53-38.36) and 69.96% (95% CI: 67.87-71.98), respectively. Compared to 1 risk factor, the odds ratios (ORs) of CVDs with 2, 3 or 4 risk factors were 1.94 (95% CI: 0.74-5.09), 2.76 (95% CI: 1.06-7.21) and 5.84 (95% CI: 1.68-20.26), respectively. Additionally, compared to i-IFGs, ORs of CVDs with i-IGT and IFG/IGT were 2.88 (95%CI 1.36-6.01) and 2.12 (95% CI 0.83-5.44), respectively.The prevalence of cardiovascular risk factors was high in the Chinese impaired glucose regulation population. The postprandial hyperglycemia is more associated with CVD than isolated fasting hyperglycemia.

Neuregulin-1 protects against doxorubicin-induced apoptosis in cardiomyocytes through an Akt-dependent pathway

In previous studies, it has been shown that recombinant human neuregulin-1(rhNRG-1) is capable of improving the survival rate in animal models of doxorubicin (DOX)-induced cardiomyopathy; however, the underlying mechanism of this phenomenon remains unknown. In this study, the role of rhNRG-1 in attenuating doxorubicin-induce apoptosis is confirmed. Neonatal rat ventricular myocytes (NRVMs) were subjected to various treatments, in order to both induce apoptosis and determine the effects of rhNRG-1 on the process. Activation of apoptosis was determined by observing increases in the protein levels of classic apoptosis markers (including cleaved caspase-3, cytochrome c, Bcl-2, BAX and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining). The activation of Akt was detected by means of western blot analysis. The study results showed that doxorubicin increased the number of TUNEL positive cells, as well as the protein levels of cleaved caspase-3 and cytochrome c, and reduced the ratio of Bcl-2/Bax. However, all of these effects were markedly antagonized by pretreament with rhNRG-1. It was then further demonstrated that the effects of rhNRG-1 could be blocked by the phosphoinositole-3-kinase inhibitor LY294002, indicating the involvement of the Akt process in mediating the process. RhNRG-1 is a potent inhibitor of doxorubicin-induced apoptosis, which acts through the PI3K-Akt pathway. RhNRG-1 is a novel therapeutic drug which may be effective in preventing further damage from occurring in DOX-induced damaged myocardium.

Serotonin modulates outward potassium currents in mouse olfactory receptor neurons

Monoaminergic neurotransmitter 5-hydroxytryptamine (5-HT), also known as serotonin, plays important roles in modulating the function of the olfactory system. However, thus far, the knowledge about 5-HT and its receptors in olfactory receptor neurons (ORNs) and their physiological role have not been fully characterized. In the present study, reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed the presence of 5-HT(1A) and 5-HT(1B) receptor subtypes in mouse olfactory epithelium at the mRNA level. With subtype selective antibodies and standard immunohistochemical techniques, both receptor subtypes were found to be positively labeled. To further elucidate the molecular mechanisms of 5-HT act on the peripheral olfactory transduction, the whole-cell patch clamp techniques were used on freshly isolated ORNs. We found that 5-HT decreased the magnitude of outward K(+) current in a dose-dependent manner and these inhibitory effects were markedly attenuated by the 5-HT(1A) receptor blocker WAY-100635 and the 5-HT(1B) receptor antagonist GR55562. These data suggested that 5-HT may play a role in the modulation of peripheral olfactory signals by regulating outward potassium currents, both 5-HT(1A) and 5-HT(1B) receptors were involved in this regulation.

The biological effects and mechanisms of calcitonin gene-related peptide on human endothelial cell

BACKGROUND

Calcitonin gene-related peptide (CGRP) is a neuropeptide distributed in bone tissue involved in bone remodeling. Previously we demonstrated that CGRP can promote proliferation and migration of endothelial cells, relating to the expression of vascular endothelial growth factor (VEGF) and focal adhesion kinase (FAK).

METHODS

CGRP1 receptor expression in human umbilical vein endothelial cells (HUVECs) was examined by immunofluorescence microscopy and real-time PCR. Tube formation was measured by a Matrigel tube formation assay. VEGF protein and mRNA levels were quantified by ELISA and real-time PCR, respectively. The expression of VEGF receptor 1 (FLT1) and VEGF receptor 2 (KDR) were measured by real-time PCR and immunoblotting assays.

RESULTS

CGRP significantly induced vascular tube formation of outgrowth HUVECs in a Matrigel. The expression of FLT and KDR were significantly increased by CGRP, and CGRP enhanced the expression of CGRP1 receptors. Compared to the known angiogenesis regulator VEGF(165), CGRP had an equal or stronger effect on migration and tube formation, but not on proliferation of endothelial cells. The upregulation of calcitonin receptor-like receptor (CRLR), FAK, VEGF and its two main receptors (FLT1, KDR) by CGRP was also more pronounced than that obtained by VEGF(165).

CONCLUSION

It is concluded that CGRP is a strong proangiogenic growth factor, thereby contributing to bone development and remodeling by promoting angiogenesis.

[Diaphragm dysfunction and expressions of calcium regulatory proteins in diabetic rats]

OBJECTIVE

To study the changes in diaphragmatic function and gene expressions of calcium regulatory proteins in diabetic rats and explore the mechanism of diaphragm dysfunction in diabetes mellitus.

METHODS

SD rats were randomly divided into normal control group and diabetic (induced by intraperitoneal STZ injection) group. After 4 and 8 weeks, the body weight and diaphragm to body weight ratio were measured, and the activities of succinic dehydrogenase (SDH) in the diaphragm and blood glucose were assayed. The diaphragm contractility was assessed and the alterations of diaphragm ultrastructure were observed. RT-PCR was used to detect the changes in sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) and phospholamban (PLB) mRNA expressions in the diaphragm.

RESULTS

The diabetic rats showed a significant weight loss with a lowered diaphragm to body weight ratio (P<0.01) and SDH activity (P<0.01). The peak twitch tension and maximum tetanic tension of the diaphragm were significantly lowered and the time to peak contraction and half relaxation time significantly prolonged (P<0.01) in the diabetic rats, which also exhibited a lowered tetanic force in response to stimulus (P<0.01). Transmission electron microscopy revealed obvious ultrastructural changes of the diaphragm in diabetic rats. RT-PCR showed significantly decreased SERCA and increased PLB mRNA expressions in diabetic rat diaphragm (P<0.01), and these changes intensified with time (P<0.01).

CONCLUSION

Diabetes can cause impairment of diaphragmatic ultrastructure, mitochondrial injuries, and lowered SDH activity and ATP production. Decreased SERCA and increased PLB mRNA expressions in diabetes result in reduced Ca(2+) uptake by the diaphragm sarcoplasmic reticulum to induce diaphragm dysfunction.

Epitope recognition patterns of thyroglobulin antibody in sera from patients with Hashimoto's thyroiditis on different thyroid functional status

Thyroglobulin antibody (TgAb) is a diagnostic serological marker of Hashimoto's thyroiditis (HT). The pathogenesis of HT progression from euthyroidism to hypothyroidism is still not clear. Epitope recognition patterns of TgAb have been shown to be different in individuals who are euthyroid or who have clinical disease. The aim of our study was to investigate the role of thyroglobulin (Tg) epitope specificities in HT progression. Sera from 107 patients with newly diagnosed HT were collected and divided into three groups: patients with hypothyroidism (H, n = 39), subclinical hypothyroidism (sH, n = 31) and euthyroidism (Eu, n = 37). A panel of Tg murine monoclonal antibodies (mAb: PB2, 5E6, 1D4, 5F9, Tg6) and a hircine pAb (N15) were employed as the probe antibodies to define the antigenic determinants recognized by HT sera on competitive enzyme-linked immunosorbent assays (ELISAs). Eight of 39 sera samples in H and seven of 31 in sH inhibited PB2 binding, respectively, whereas none did in Eu. The ratio of sera samples, inhibiting PB2 binding in Eu, was significantly lower than that in H (P = 0.011) and in sH (P = 0.008). For N15, five of 39 sera samples in H, six of 31 in sH and 15 of 37 in Eu inhibited its binding, respectively. The ratio of sera samples, inhibiting N15 binding in Eu, was significantly higher than that in H (P = 0.013). Our study demonstrated that HT patients in different thyroid functional status exhibited different Tg epitope recognition patterns. Epitope patterns of TgAb might be used as a prediction marker of HT progression.

Abstract PD05-09: Whole-genome progression of breast cancer from early neoplasia to invasive carcinoma

Cancer evolution involves cycles of genomic damage, epigenetic deregulation, and increased cellular proliferation that eventually culminate in the carcinoma phenotype. Early breast neoplasias include usual ductal hyperplasia, columnar cell lesions, and flat epithelial atypia and some are thought to represent precursor stages. To elucidate their role in cancer evolution we performed comparative whole genome sequencing of early neoplasias, matched normal tissue, and carcinomas from six patients. The identified somatic mutations served as lineage markers to build trees that relate the tissue samples. On the basis of the lineage trees we inferred the order, timing, and rates of mutational events. We find that in a subset of cases, the last common ancestor of an early neoplasm and a carcinoma was hypermutated and had several aneuploidies, and that evolution further accelerated in the carcinoma lineage. In contrast to highly advanced tumors that are the focus of much of current cancer genome sequencing, the early neoplasia genomes, and the carcinomas as well, harbor a striking paucity of potentially functional somatic point mutations. The earliest significant events we could detect, those changes that occurred in common ancestors of neoplastic and tumor cells, are aneuploidies. Several aneuploidies are recurrent, suggesting that they are among the earliest genomic events that predispose breast tissue to eventual development of invasive carcinoma.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD05-09.

Uptake of silica and carbon nanotubes by human macrophages/monocytes induces activation of fibroblasts in vitro -- potential implication for pathogenesis of inflammation and fibrotic diseases

The potential pathogenic effects of silica and carbon nanotubes (CNTs) on fibroblasts, macrophages/monocytes, and T cells were investigated. Human macrophage/monocytes were cultured and stimulated with silica, CNTs, or titanium particles. After adding human T cells to the stimulated macrophages/monocytes, the cells were added to cultured human fibroblasts. Upon microscopic examination, CNT stimulation after 24 hours showed centralization of macrophages/monocytes around the CNTs. Silica stimulation showed a significant increase of IL-1α and IL-1β in cultured medium, and an increased gene expression of CTGF in cultured fibroblasts at 1 hour, as well as an up-regulation of the COL1A2 gene at 24-hour time point. In addition to the same changes of IL-1α, IL-1β and the COL1A2 by silica, CNT stimulation showed an increase of IL-8 in cultured medium at 1-hour time point. Titanium stimulation yielded no significant changes. The results indicate a proinflammatory and/or profibrotic effect of silica and CNTs to cultured human cells including macrophages/monocyte, T cells and fibroblasts.

The role of the sensory nerve response in ultrasound accelerated fracture repair

This study was designed to test the hypothesis that the sensory innervation of bone might play an important role in sensing and responding to low-intensity pulsed ultrasound and explain its effect in promoting fracture healing. In 112 rats a standardised mid-shaft tibial fracture was created, supported with an intramedullary needle and divided into four groups of 28. These either had a sciatic neurectomy or a patellar tendon resection as control, and received the ultrasound or not as a sham treatment. Fracture union, callus mineralisation and remodelling were assessed using plain radiography, peripheral quantitative computed tomography and histomorphology. Daily ultrasound treatment significantly increased the rate of union and the volumetric bone mineral density in the fracture callus in the neurally intact rats (p = 0.025), but this stimulating effect was absent in the rats with sciatic neurectomy. Histomorphology demonstrated faster maturation of the callus in the group treated with ultrasound when compared with the control group. The results supported the hypothesis that intact innervation plays an important role in allowing low-intensity pulsed ultrasound to promote fracture healing.