Novel Small Molecule Glucagon-Like Peptide-1 Receptor Agonist Stimulates Insulin Secretion in Rodents and From Human Islets

OBJECTIVE

The clinical effectiveness of parenterally-administered glucagon-like peptide-1 (GLP-1) mimetics to improve glucose control in patients suffering from type 2 diabetes strongly supports discovery pursuits aimed at identifying and developing orally active, small molecule GLP-1 receptor agonists. The purpose of these studies was to identify and characterize novel nonpeptide agonists of the GLP-1 receptor.

RESEARCH DESIGN AND METHODS

Screening using cells expressing the GLP-1 receptor and insulin secretion assays with rodent and human islets were used to identify novel molecules. The intravenous glucose tolerance test (IVGTT) and hyperglycemic clamp characterized the insulinotropic effects of compounds in vivo.

RESULTS

Novel low molecular weight pyrimidine-based compounds that activate the GLP-1 receptor and stimulate glucose-dependent insulin secretion are described. These molecules induce GLP-1 receptor-mediated cAMP signaling in HEK293 cells expressing the GLP-1 receptor and increase insulin secretion from rodent islets in a dose-dependent manner. The compounds activate GLP-1 receptor signaling, both alone or in an additive fashion when combined with the endogenous GLP-1 peptide; however, these agonists do not compete with radiolabeled GLP-1 in receptor-binding assays. In vivo studies using the IVGTT and the hyperglycemic clamp in Sprague Dawley rats demonstrate increased insulin secretion in compound-treated animals. Further, perifusion assays with human islets isolated from a donor with type 2 diabetes show near-normalization of insulin secretion upon compound treatment.

CONCLUSIONS

These studies characterize the insulinotropic effects of an early-stage, small molecule GLP-1 receptor agonist and provide compelling evidence to support pharmaceutical optimization.Hyperglucagonemia and dysregulation of insulin secretion impair postprandial glucose homeostasis and thus are central to the pathogenesis of type 2 diabetes. Impairment of the incretin effect, including reduced secretion of glucagon-like peptide-1 (GLP-1) (1,2), is implicated in the progression of pancreatic islet dysfunction in type 2 diabetic patients. Development and use of incretin-based therapeutics may, therefore, be an effective strategy to restore normal islet function by providing insulinotropic and glucagon-suppressive capabilities. In recent years, clinical studies have shown that replacement therapy with metabolically stable GLP-1 mimetics greatly improves management of hyperglycemia, nearly correcting blood glucose regulation for some patients. For example, treatment with either exenatide or liraglutide reduces fasting hyperglycemia and results in sustained lowering of glycosylated A1C (A1C) levels (3,4). In addition, these therapies often reduce body weight and improve several cardiovascular parameters (5,6). Unfortunately, both of these GLP-1 analogues are peptides requiring administration by subcutaneous injection.The GLP-1 receptor is a member of the class B/II family of seven transmembrane G protein-coupled receptors (GPCRs) that include receptors for peptide hormones such as secretin, GLP-1, glucose-dependent insulinotropic polypeptide (GIP), glucagon, vasoactive intestinal peptide (VIP), corticotropin-releasing factor (CRF), calcitonin, and parathyroid hormone (PTH) (7–9). Historically, the discovery of nonpeptide agonists of these receptors that could enable development of orally active pharmaceuticals has been generally unsuccessful. To a large extent, this difficulty has been attributed to the mechanisms used by class B GPCRs to recognize ligands and induce signaling. Interaction of endogenous peptide hormones with their receptors typically involves large receptor:ligand binding sites and is often initiated by receptor NH₂-terminal ectodomains (ECDs). This extracellular structure interacts with COOH-terminal residues of cognate ligands and positions the NH₂-terminus of the ligand to interact with critical determinants in receptor transmembrane regions, thereby activating heterotrimeric G-proteins and subsequently adenylyl cyclase (10–12).The recent reports describing GLP-1 receptor activation by a series of substituted quinoxalines (13–16) and a cyclobutane derivative (17) suggest that it may be possible to develop nonpeptide GLP-1 receptor agonists. Both scaffolds activate GLP-1 receptor signaling in heterologous GLP-1 receptor-expressing cellular systems, and the quinoxalines clearly induce glucose-stimulated insulin secretion in vitro from rodent islets and ex vivo via perfused pancreas (13,16). We now report novel, low molecular weight pyrimidines that activate the GLP-1 receptor to induce glucose-dependent insulin secretion both in vitro and in vivo. These molecules may offer therapeutic advantage because of the ability of the compounds to act alone or in combination with GLP-1. Further, these agonists nearly restore insulin secretion to normal in human diabetic islets.     

HIV/AIDS selective infectivity–report of two peculiar cases

We report two peculiar cases that were observed in two communities of Anambra State, South East Nigeria. The first case was a woman of 44 with a history of blood transfusion from a donor of questionable HIV status. A pint of blood was transfused in a private Hospital on the 15 th January, 2000. She has had no form of antiviral therapy until 22nd April, 2008 when she came to the hospital for routine medical check up. Her HIV result came out confirmed positive while that of her husband came out negative. She has had active sexual life with her husband in the previous eight years as they have had some difficulties in getting their desired extra two children having earlier gotten a boy and a girl. The second case involves a family of six. A couple with four children of ages about 6 months, 2 years, 3 years and 5 years. The youngest, a female presented with fever and multiple lymphadenopathy. She tested HIV positive and so was her mother and her second sibling. But her father and two other siblings remained negative at post three and six months intervals from their very first test date with us. These reported cases appear to go contrary to earlier formed opinion on HIV transmission. We support the opinion on a naturally, occurring substance, APOBEC3G which possibly confers permanent immunity against the HIV virus. We recommend clinical trials of the characterized APOBEC3G as a vaccine for non HIV infected persons of all ages and to people living with as a therapeutic drug.     

The associations of parity and maternal age with small-for-gestational-age,preterm, and neonatal and infant mortality: a meta-analysis

Background

Previous studies have reported on adverse neonatal outcomes associated with parity and maternal age. Many of these studies have relied on cross-sectional data, from which drawing causal inference is complex. We explore the associations between parity/maternal age and adverse neonatal outcomes using data from cohort studies conducted in low- and middle-income countries (LMIC).

Methods

Data from 14 cohort studies were included. Parity (nulliparous, parity 1-2, parity ≥3) and maternal age (<18 years, 18-<35 years, ≥35 years) categories were matched with each other to create exposure categories, with those who are parity 1-2 and age 18-<35 years as the reference. Outcomes included small-for-gestational-age (SGA), preterm, neonatal and infant mortality. Adjusted odds ratios (aOR) were calculated per study and meta-analyzed.

Results

Nulliparous, age <18 year women, compared with women who were parity 1-2 and age 18-<35 years had the highest odds of SGA (pooled adjusted OR: 1.80), preterm (pooled aOR: 1.52), neonatal mortality (pooled aOR: 2.07), and infant mortality (pooled aOR: 1.49). Increased odds were also noted for SGA and neonatal mortality for nulliparous/age 18-<35 years, preterm, neonatal, and infant mortality for parity ≥3/age 18-<35 years, and preterm and neonatal mortality for parity ≥3/≥35 years.

Conclusions

Nulliparous women <18 years of age have the highest odds of adverse neonatal outcomes. Family planning has traditionally been the least successful in addressing young age as a risk factor; a renewed focus must be placed on finding effective interventions that delay age at first birth. Higher odds of adverse outcomes are also seen among parity ≥3 / age ≥35 mothers, suggesting that reproductive health interventions need to address the entirety of a woman’s reproductive period.

Funding

Funding was provided by the Bill & Melinda Gates Foundation (810-2054) by a grant to the US Fund for UNICEF to support the activities of the Child Health Epidemiology Reference Group.

     

Oral fungal and bacterial infections in HIV-infected individuals: an overview in Africa

Oral opportunistic infections developing secondary to human immunodeficiency virus (HIV) infection have been reported from the early days of the epidemic and have been classified by both the EC-Clearinghouse and the World Health Organisation (WHO). Among the fungal infections, oral candidiasis, presenting in African HIV-infected patients has been sporadically documented. We review the literature with respect to candidal carriage, oral candidiasis prevalence and the predictive value of oral candidiasis for a diagnosis of underlying HIV disease in African HIV-infected patients. The use of oral candidiasis as a marker of disease progression, the species of yeasts isolated from the oral cavity in Africa and the resistance of the yeasts to antifungal agents and treatment regimens are discussed. Orofacial lesions as manifestations of the systemic mycoses are rarely seen in isolation and few cases are reported in the literature from Africa. In spite of the high incidence of noma, tuberculosis, chronic osteomyelitis and syphilis in Africa, surprisingly there have been very few reported cases of the oral manifestations of these diseases in HIV-positive individuals. Orofacial disease in HIV-infected patients is associated with marked morbidity, which is compounded by malnutrition. The authors indicate specific research areas, initially directed at the most effective management strategies, which would complete data in this important area.     

Increase in sensitization to oil of turpentine: recent data from a multicenter study on 45,005 patients from the German-Austrian Information Network of Departments of Dermatology (IVDK)

Contact allergy to oil of turpentine was reported to have become rare. However, the evaluation of standardized data of 45,005 patients tested 1992-1997 in 30 Dermatological Centers associated with the German-Austrian Information Network of Departments of Dermatology (IVDK) showed an increase in positive patch test reactions to turpentine from 0.5% during the years 1992-1995, up to 1.7% in 1996 and 3.1% in 1997. In particular, 17,347 patients tested in 1996-1997 were evaluated in detail by comparing 431 individuals with positive patch test reactions with the rest of the group found negative to turpentine. Using the so-called MOAHLFA index, the following characteristics were shown. Turpentine allergy (a) was found to be significantly less frequent in men and in patients with occupational dermatitis, (b) showed no difference in its association with atopic dermatitis, (c) patients with turpentine allergy had significantly less symptoms of the hands, more symptoms of the legs or in the face and (d) were significantly more often aged over 60 years. Also, patients sensitized to turpentine had increased rates of additional sensitizations. The definite reason for the increase in turpentine sensitization in the population tested here is not clear. Therefore, a detailed exposure analysis is necessary; the new increase in turpentine allergies may be due to popular topical remedies or household chemicals.     

De novo 16p13.11 microdeletion identified by high-resolution array CGH in a fetus with increased nuchal translucency

Objective  We investigated the application of high-resolution microarray-based comparative genomic hybridisation (array CGH) on a fetus showing increased nuchal translucency (NT).
Design  Case study.
Setting  Tertiary referral obstetrics unit.
Sample  Pregnant woman attended the antenatal clinic.
Methods  Conventional karyotyping and genetic test was carried out for the alpha-globin gene. High-resolution array CGH using the high-density 244K Agilent microarray was performed on fetal blood sample by cordocentesis to investigate the possibility of any genomic imbalance.
Main outcome measures  Detection of chromosomal abnormality.
Results  Karyotyping analysis showed 46,XY. Molecular genetic diagnosis confirms the fetus has Hb-H constant spring disease but cannot explain the increased NT to 3.2 mm. Array CGH analysis discovered a 1.32-Mb microdeletion on chromosome 16p13.11. Deletion at 16p13.11 has been implicated to predispose to autism and/or mental retardation. Baby was delivered at 40 weeks of gestation, and follow up was carried out at 3 months of age without sign of mental retardation/developmental delay.
Conclusions  This case study demonstrated that array CGH can accurately calibrate the size and identify de novo interstitial chromosome imbalances. However, the presence of chromosome copy variants with unknown clinical significance currently limits its wider scale application in prenatal diagnosis and needs further investigations.     

Does Elbow Position Affect Strength and Reproducibility of Power Grip Measurements?

Effects of elbow positioning on grip strength and its between-day reliability of measurement were tested bilaterally in 30 healthy adults. Grip strength was measured twice with a Jamar dynamometer at 0°, 30°, 60°, 90° and 120° of elbow flexion one week apart. Intraclass correlation coefficient model_(1,1) was > 0.987 for each test, and limits of agreement reveal narrow ranges of the 95% confidence intervals for each test, which reflect good between-day reliability for these measurements in both absolute and relative terms. Grip strength at 120° was significantly lower than all other positions on both sides (p < 0.001), whereas the grip strength at 90° was highest among all positions tested. The grip strengths at 0°, 30° and 60° were, in general, 0.5-3% lower than the measurements taken at 90° of elbow flexion, but the differences were not statistically significant. These findings suggest that between-day comparison of grip strength is valid and reproducible in the same testing position, and 120° of elbow flexion is not a desirable position for grip strengthening exercise. The differences in grip strength can be explained by the length-tension relationship and the clinical implications for these findings are discussed.