Characterization of glucagon-like peptide-1 receptor-binding determinants

Glucagon-like peptide 1 (GLP-1) is a potent insulinotropic hormone currently under study as a therapeutic agent for type 2 diabetes. Since an understanding of the molecular mechanisms leading to high-affinity receptor (R) binding and activation may facilitate the development of more potent GLP-1R agonists, we have localized specific regions of GLP-1R required for binding. The purified N-terminal fragment (hereafter referred to as NT) of the GLP-1R produced in either insect (Sf9) or mammalian (COS-7) cells was shown to bind GLP-1. The physical interaction of NT with GLP-1 was first demonstrated by cross-linking ((125)I-GLP-1/NT complex band at approximately 28 kDa) and secondly by attachment to Ni(2+)-NTA beads. The GLP-1R NT protein attached to beads bound GLP-1, but with lower affinity (inhibitory concentration (IC(50)): 4.5 x 10(-7) M) than wild-type (WT) GLP-1R (IC(50): 5.2 x 10(-9)M). The low affinity of GLP-1R NT suggested that other receptor domains may contribute to GLP-1 binding. This was supported by studies using chimeric glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptors. GIP(1-151)/GLP-1R, but not GIP(1-222)/GLP-1R, exhibited specific GLP-1 binding and GLP-1-induced cAMP production, suggesting that the region encompassing transmembrane (TM) domain 1 through to TM3 was required for binding. Since it was hypothesized that certain charged or polar amino acids in this region might be involved in binding, these residues (TM2-TM3) were analyzed by substitution mutagenesis. Five mutants (K197A, D198A, K202A, D215A, R227A) displayed remarkably reduced binding affinity. These studies indicate that the NT domain of the GLP-1R is able to bind GLP-1, but charged residues concentrated at the distal TM2/extracellular loop-1 (EC1) interface (K197, D198, K202) and in EC1 (D215 and R227) probably contribute to the binding determinants of the GLP-1R.     

Pulmonary embolism in a patient with multiple myeloma receiving thalidomide–dexamethasone therapy

Massive pulmonary embolism is an uncommon complication of multiple myeloma treated with thalidomide-dexamethasone regimen. In 2006, multiple myeloma was diagnosed in a 72-year-old man, who received thalidomide-dexamethasone therapy. In January 2007, echocardiography and computerized tomography identified massive pulmonary embolism in the pulmonary arteries and a deep vein thrombus of the right leg. The patient also had an elevated concentration of B-type natriuretic peptide. After heparinization and warfarin therapy, the patient's condition improved. This is the first report of a patient with a rare complication of pulmonary embolism from thalidomide-treated multiple myeloma.     

Elevated tricuspid regurgitant jet velocity in subgroups of thalassemia patients: insight into pathophysiology and the effect of splenectomy

A high tricuspid regurgitant jet velocity (TRV) signifies a risk for or established pulmonary hypertension (PH), which is a serious complication in thalassemia patients. The underlying pathophysiology in thalassemia subgroups and potential biomarkers for early detection and monitoring are not well defined, in particular as they relate to spleen removal. To better understand some of these unresolved aspects, we examined 76 thalassemia patients (35 non-transfused), 25 splenectomized non-thalassemia patients (15 with hereditary spherocytosis), and 12 healthy controls. An elevated TRV (>2.5 m/s) was found in 25/76 (33 %) of the patients, confined to non-transfused or those with a late start of transfusions, including patients with hemoglobin H-constant spring, a finding not previously described. These non or late-transfused patients (76 % splenectomized) had significantly increased platelet activation (sCD40L), high platelet count, endothelial activation (endothelin-1), and hemolysis (LDH, plasma-free Hb), while hypercoagulable and inflammatory markers were not significantly increased. The same markers were increased in the seven patients with confirmed PH on cardiac catheterization, suggesting their possible role for screening patients at risk for PH. A combination of hemolysis and absence of spleen is necessary for developing a high TRV, as neither chronic hemolysis in the non-splenectomized thalassemia patients nor splenectomy without hemolysis, in the non-thalassemia patients, resulted in an increase in TRV.     

Randomized controlled trial of two dosing schedules for human papillomavirus vaccination among college age males

Background

Quadrivalent human papillomavirus (HPV) vaccine, for protection against sexually transmitted HPV infection, is licensed for females and males 9–26 years on a 3-dose schedule (0, 2, and 6 months; Standard schedule). Vaccine uptake has been low and catch-up vaccination of older adolescents using an alternate dosing schedule may increase coverage. This study tested the non-inferiority of the immunogenicity of an alternate dosing schedule (0, 2, 12 months) among college age males.

Methods

220 18–25 year old males were randomly assigned to Standard or Alternate schedules. Blood samples were drawn immediately before Dose 1 and 2–6 weeks after Dose 3 and analyzed for antibody titers using a Luminex immunoassay. A value <1.5 for the upper 95% confidence interval (CI) bound of the Standard to Alternate schedule geometric mean titer (GMT) ratio was deemed non-inferior.

Results

Participants averaged 21.3 years old; 19.1% were non-white; completion rate was 93%. The anti-HPV titers for the Alternate schedule group were non-inferior to those of Standard schedule group for all four HPV vaccine virus types. Our results also demonstrated superiority of the Alternate schedule group for all four HPV vaccine virus types.

Conclusion

A delayed third dose at 12 months is immunologically non-inferior and superior for four HPV virus types. Using an alternate dosing schedule offers more flexibility to receive the 3-dose HPV vaccine and may result in higher vaccination rates among college-age males.     

Sleep in mothers of children with epilepsy and its relation to their children's sleep

We conducted a cross-sectional study to examine sleep in mothers of children with epilepsy and its relation to their children's sleep. A total of 133 dyads of mothers and children with epilepsy aged 1.5–6 years were recruited between 2015 and 2018 from a children's hospital in northern Taiwan. Participating families provided demographic and health information, with children wearing an actigraphy monitor for 7 days and mothers completing sleep and depressive mood questionnaires. We found that 76 (57.1%) of the mothers had poor sleep quality, with 65 (48.9%) mothers having a clinically significant depressive symptom score. Mean actigraphic wake after sleep onset in children was 1.42 (standard deviation = 0.51) hours, with 126 (94.7%) of the children having a clinically significant sleep disturbance score. Multivariate regression analyses showed that higher depressive symptom scores in mothers (β = 0.14; p < .01) and higher sleep disturbance scores in children (β = 0.07; p = .04) were associated with poorer maternal sleep quality, even when maternal demographic characteristics and the child's clinical and epilepsy variables were considered. Findings from our study suggest that sleep disturbances are a shared problem for mothers and their children with epilepsy. Sleep in both mothers and their children with epilepsy should be evaluated in pediatric neurologic practices, with maternal depressive symptoms screened concurrently. Future pediatric epilepsy studies are warranted to examine whether a family-based intervention program would be effective to improve sleep in mother-child dyads and to promote better health and functioning of the entire family.     

Approaches for Detection of Hepatitis B Virus Pre-S Gene Deletions and Pre-S Deleted Proteins and Their Application in Prediction of Higher Risk of Hepatocellular Carcinoma Development and Recurrence

Hepatocellular carcinoma (HCC) is among the most common and lethal human cancers worldwide and is closely associated with chronic hepatitis B virus (HBV) infection. Pre-S deleted proteins are naturally occurring mutant forms of HBV large surface proteins that are expressed by HBV surface genes harboring deletion mutations over the pre-S gene segments. It has been well demonstrated that HBV pre-S deleted proteins function as important oncoproteins, which promote malignant phenotypes of hepatocytes through the activation of multiple oncogenic signaling pathways and result in HCC formation. The oncogenic signaling pathways activated by pre-S deleted proteins have been verified as potential therapeutic targets for the prevention of HCC development. Moreover, the presence of pre-S gene deletions and the expression of pre-S deleted proteins in the blood and liver tissues of HBV-infected patients have been evaluated as valuable biomarkers for predicting a higher risk of HCC development and recurrence after curative surgical resection. Therefore, the precise detection of pre-S gene deletions and pre-S deleted proteins holds great promise as regards identifying the patients at higher risk of HCC development and recurrence, thus aiding in more timely and better treatments to improve their survival. This review summarizes the major approaches used for the detection of pre-S gene deletions and pre-S deleted proteins, including the approaches based on Sanger DNA sequencing, pre-S gene chips, next-generation sequencing and immunohistochemistry staining, and it highlights their important applications in the prediction of higher risks of HCC development and recurrence.     

ADAM-10 and -17 regulate endometriotic cell migration via concerted ligand and receptor shedding feedback on kinase signaling

A Disintegrin and Metalloproteinases (ADAMs) are the principal enzymes for shedding receptor tyrosine kinase (RTK) ectodomains and ligands from the cell surface. Multiple layers of activity regulation, feedback, and catalytic promiscuity impede our understanding of context-dependent ADAM “sheddase” function and our ability to predictably target that function in disease. This study uses combined measurement and computational modeling to examine how various growth factor environments influence sheddase activity and cell migration in the invasive disease of endometriosis. We find that ADAM-10 and -17 dynamically integrate numerous signaling pathways to direct cell motility. Data-driven modeling reveals that induced cell migration is a quantitative function of positive feedback through EGF ligand release and negative feedback through RTK shedding. Although sheddase inhibition prevents autocrine ligand shedding and resultant EGF receptor transactivation, it also leads to an accumulation of phosphorylated receptors (HER2, HER4, and MET) on the cell surface, which subsequently enhances Jnk/p38 signaling. Jnk/p38 inhibition reduces cell migration by blocking sheddase activity while additionally preventing the compensatory signaling from accumulated RTKs. In contrast, Mek inhibition reduces ADAM-10 and -17 activities but fails to inhibit compensatory signaling from accumulated RTKs, which actually enhances cell motility in some contexts. Thus, here we present a sheddase-based mechanism of rapidly acquired resistance to Mek inhibition through reduced RTK shedding that can be overcome with rationally directed combination inhibitor treatment. We investigate the clinical relevance of these findings using targeted proteomics of peritoneal fluid from endometriosis patients and find growth-factor–driven ADAM-10 activity and MET shedding are jointly dysregulated with disease.A Disintegrin and Metalloproteinases (ADAMs), especially ADAM-10 and -17, are the principal mediators of proteolytic ectodomain shedding on the cell surface (1). ADAMs and the closely related matrix metalloproteinases (MMPs) work together as “sheddases” to cleave hundreds of diverse transmembrane substrates including growth factor ligands, receptor tyrosine kinases (RTKs), adhesion molecules, and even proteases themselves from the cell surface. Unfortunately, little is known regarding how such a broad palette of proteolytic activity integrates to modulate behaviors such as cellular motility. Furthermore, extensive cross-talk and complexity among signaling networks, proteases, and their substrates make understanding sheddase regulation on a component-by-component basis challenging (2). Therapeutics have targeted sheddases and their substrates for the treatment of invasive diseases such as cancer, yet many of these inhibitors have failed in clinical trials (3). Therefore, a need exists for understanding how the balance of sheddase-mediated degradation integrates multiple layers of signaling networks to coordinately influence cell behavior in various disease contexts.Here we study how sheddase activity contributes to cell migration in the invasive disease of endometriosis, defined by the presence of endometrial-like tissue residing outside the uterus. Up to 10% of adult females and 40% of infertile women have the disease, which also exhibits comorbidity with several cancers (4, 5). Endometriosis currently has no cure: hormonal therapies merely manage the disease with significant side effects, and surgery provides only temporary relief for many, with recurrence rates as great as 40% within 5 y postoperation (6). Like cancer, endometriosis is associated with aberrant cell invasion into ectopic organ sites, and endometriotic tissues often exhibit dysregulated molecular pathways commonly perturbed in other invasive diseases. Mitogenic and inflammatory phospho-signaling [for example, phosphorylated extracellular-signal-related kinase 1/2 (p-Erk1/2), phosphorylated protein kinase B (p-Akt), and phosphorylated p38 mitogen-activated protein kinase (p-p38)], RTKs (including epidermal growth factor receptor, EGFR), and metalloproteinases have all been clinically associated with endometriosis (7, 8), and consequently represent attractive therapeutic strategies (9–11).Many challenges in developing targeted therapeutics stem from network-level complexities such as compensatory feedback, and recent work has demonstrated how critical such mechanisms are to achieving therapeutic success, especially in cancer (12, 13). Computational models of systems-level biochemical networks have shown promise as tools to understand how multiple enzymatic reactions integrate to impact overall biological behavior, often with the goal of aiding the design of personalized or combination therapies (14, 15). Considering its complex role in disease, sheddase regulation represents an ideal application of such network-level approaches. In this work, we apply the “cue–signal–response” (CSR) paradigm (14, 15) (Fig. 1A) to examine how disease-implicated growth-factor cues interact with experimentally monitored phospho-protein and protease networks (collectively referred to as signals), ultimately to influence cellular migration response. Computational modeling elucidates quantitative and predictive relationships among multiple layers of experimental data and offers testable hypotheses of context-dependent behavior and signaling feedback. We find ADAM-10 and -17 to be critical regulators of motility that are dynamically controlled through several signaling pathways, thereby affecting cell behavior through both positive feedback from EGF ligand release and negative feedback from Hepatocyte Growth Factor Receptor (HGFR; MET), Human Epidermal Growth Factor Receptor 2 (HER2), and HER4 RTK shedding. We find kinase inhibition generally reduces ADAM-10 and -17 activities, reduces subsequent RTK shedding, and consequently allows the accumulated RTKs to enhance downstream c-Jun N-terminal kinase (Jnk) and p38 signaling. Thus, here we demonstrate an ADAM-10 and -17–based mechanism of rapidly acquired resistance to kinase inhibition through reduced RTK shedding that can be overcome with combination therapy. Targeted proteomic analysis of clinical samples from endometriosis patients indeed confirms growth-factor–driven ADAM-10 activity and consequent MET shedding are dysregulated with disease. Overall, our results have wide implications for designing combination therapies and identifying context-dependent personalized therapeutic strategies for both kinase and protease inhibitors.Open in a separate windowFig. 1.CSR study design. (A) CSR overview: we stimulate endometriotic cells with a panel of growth factor cues; record multiple downstream signals comprising measurements of phospho-signaling, sheddase regulation, and sheddase substrate regulation; and use computational modeling to map these observations onto cell migration responses. (B) Overview of signals and responses included in the CSR dataset. All receptors shown were directly measured and/or stimulated. (C) Experimental timeline of CSR study. Dark colored lines denote measurement time points. At lower left, cell migration is depicted as single-cell tracks, where initial cell positions were centered for visualization.     

Effects of methylprednisolone on the neural conduction of the motor evoked potentials in spinal cord injured rats

Methylprednisolone(MP), a glucocorticoid steroid, has an anti-inflammatory action and seems to inhibit the formation of oxygen free radicals produced during lipid peroxidation in a spinal cord injury(SCI). However, the effects of MP on the functional recovery after a SCI is controversial. The present study was conducted to determine the effects of MP on the recovery of neural conduction following a SCI. A SCI was produced using the NYU spinal cord impactor. A behavioral test was conducted to measure neurological disorders, and motor evoked potentials (MEPs) were recorded. According to the behavioral test, using BBB locomotor scaling, MP-treated animals showed improved functional recoveries when compared to saline-treated animals. MEP latencies in the MP-treated group were shortened when compared to those in the control group. Peak amplitudes of MEPs were larger in the MP-treated group than those in the control group. The thresholds of MEPs tended to be lower in the MP-treated group than those in the control group. These results suggest that MP may improve functional recovery after a SCI.     

Antibodies to hepatitis E virus among chinese patients with acute hepatitis in Taiwan

The prevalence of antibodies to hepatitis E virus (anti-HEV) was investigated in patients with acute hepatitis, and correlated with the clinical features. Sera from 110 patients with acute hepatitis and 60 healthy controls were tested for anti-HEV, antibody to hepatitis C virus (anti-HCV), and hepatitis B surface antigen (HBsAg). There were significant differences in the prevalence of anti-HEV, anti-HCV, and HBsAg between patients and controls (21.8% vs. 0%, 16.3% vs. 1.6% and 58.1% vs. 18.0%, respectively). Anti-HEV was detected in 6 (25.0%) of 24 patients with anti-HCV, 6 (9.3%) of 64 patients with HBsAg, and another 6 (22.2%) of 27 patients with acute hepatitis non-A, non-B, non-C. Anti-HEV was found in 15 men and three women, whose ages ranged from 34 to 75 (median, 57) years old. The median age of patients with anti-HEV was older than that in patients without this antibody (57 vs. 38 years; P = 0.001). The prevalence of anti-HEV in patients with anti-HCV alone (35.2%) was higher than that (11.1%) in patients with HBsAg alone (P = 0.03). Compared to patients without anti-HEV, HEV-infected patients had a higher frequency of travel to a foreign country (P = 0.0001), had a lower HBsAg rate (P = 0.019), and had higher serum alkaline phosphatase levels (P = 0.04) and gamma-glutamyl transpeptidase levels (P = 0.01). In conclusion, HEV infection occurs in 22.2% of patients with acute hepatitis non-A, non-B, non-C. HEV superinfection may occur in patients with chronic hepatitis B or C virus infection. © 1994 Wiley-Liss, Inc.