Methylnaltrexone inhibits opiate and VEGF-induced angiogenesis: role of receptor transactivation

Angiogenesis or the formation of new blood vessels is important in the growth and metastatic potential of various cancers. Therefore, agents that inhibit angiogenesis have important therapeutic implications in numerous malignancies. We examined the effects of methylnaltrexone (MNTX), a peripheral mu opioid receptor antagonist, on agonist-induced human EC proliferation and migration, two key components in angiogenesis. Using human dermal microvascular EC, we observed that morphine sulfate (MS), the active metabolite, morphine-6-glucuronide (M6G), DAMGO ([d-Ala(2), N-Me-Phe(4), Gly(5)-ol]enkaphalin) and VEGF induced migration which were inhibited by pretreatment with MNTX at therapeutically relevant concentration (0.1 microM). The biologically inactive metabolite morphine-3-glucuronide (M3G) did not affect EC migration. We next examined the mechanism(s) by which MNTX inhibits opioid and VEGF-induced angiogenesis using human pulmonary microvascular EC. MS and DAMGO induced Src activation which was required for VEGF receptor transactivation and opioid-induced EC proliferation and migration. MNTX inhibited MS, DAMGO and VEGF induced tyrosine phosphorylation (transactivation) of VEGF receptors 1 and 2. Furthermore, MS, DAMGO and VEGF induced RhoA activation which was inhibited by MNTX or VEGF receptor tyrosine kinase inhibition. Finally, MNTX or silencing RhoA expression (siRNA) blocked MS, DAMGO and VEGF-induced EC proliferation and migration. Taken together, these results indicate that MNTX inhibits opioid-induced EC proliferation and migration via inhibition of VEGF receptor phosphorylation/transactivation with subsequent inhibition of RhoA activation. These results suggest that MNTX inhibition of angiogenesis can be a useful therapeutic intervention for cancer treatment.     

Chronic ethanol exposure impairs neuronal nitric oxide synthase in the rat intestine

BACKGROUND: Nitric oxide (NO), synthesized by neuronal (nNOS), endothelial (eNOS), and inducible (iNOS) nitric oxide synthases, plays an essential role in the physiological functions of the gastrointestinal (GI) tract. Chronic ethanol intake has been shown to interfere with several of these physiological functions, leading to the pathological alterations observed in alcoholic individuals. Our aim therefore was to investigate the effects of chronic ethanol consumption on NOS isoforms in different GI segments. METHODS: Rats received either 20% aqueous ethanol solution or water for 8 weeks. Tissue samples of the duodenum, jejunum, ileum, and colon of the rats were used for measurement of the NOS activity, protein content, and nNOS immunohistochemistry. Anti-HuC/D immunohistochemistry was used to determine the total number of neurons. RESULTS: Measurement of the physiological constitutive NOS (cNOS) activity revealed a 20 times higher activity in the colon than in the small intestine and after chronic ethanol treatment demonstrated a significant decrease in the jejunum, ileum, and colon, while in the duodenum it remained unchanged compared with the control group. The physiological iNOS activity was higher in the ileum and colon than in the duodenum and jejunum, and these levels were not significantly affected by ethanol. Neuronal nitric oxide synthase immunohistochemistry revealed a significant decrease in the numbers of immunostained cells in all investigated intestinal segments, while the total number of myenteric neurons remained constant. The nNOS protein content measured by Western blotting indicated a significant decrease in the colon after ethanol consumption, while in other intestinal segments change was not detectable. CONCLUSIONS: This study has demonstrated for the first time that chronic ethanol consumption has a differential effect on NOS activity, NOS protein content, and the number of nitrergic neurons in different intestinal segments, suggesting that chronic ethanol administration affects the NO pathways in the enteric nervous system.     

Is preeclampsia associated with higher frequency of HSP70 gene polymorphisms?

Aim

To evaluate the possible association of three different HSP70 gene polymorphisms with preeclampsia.

Study design

HSPA1A G(190)C, HSPA1B A(1267)G and HSPA1L T(2437)C polymorphisms were analyzed from blood samples of 72 women with preeclampsia and of 70 healthy pregnant women as controls by PCR-RFLP method.

Results

HSPA1B (1267)GG and HSPA1L (2437)CC genotypes occurred more frequently in preeclamptic patients compared to healthy controls (p < 0.002 [RR: 4.38, 95% CI: 1.56–12.28]) and (p < 0.03 [RR: 1.31, 95% CI: 1.03–1.67]), respectively. Significant difference was found in the distribution of HSPA1B A(1267)G genotype between the preeclamptic and control group (p < 0.004 [RR: 0.67, 95% CI: 0.51–0.88]). Distribution of HSPA1A G(190)C was similar in the preeclamptic and control group. In controls, genotype distribution of HSPA1A G(190)C and HSPA1L T(2437)C was in Hardy–Weinberg equilibrium, while this criterion was not fulfilled for HSPA1B A(1267)G.

Conclusion

We concluded that HSPA1B (1267)GG and HSPA1L (2437)CC genotypes were more frequent among preeclamptic than control patients, suggesting that these genotypes may play a role in the susceptibility for preeclampsia.     

The neuromuscular and multisystem features of RYR1-related malignant hyperthermia and rhabdomyolysis: A study protocol

Introduction:Malignant hyperthermia (MH) and exertional rhabdomyolysis (ERM) have long been considered episodic phenotypes occurring in response to external triggers in otherwise healthy individuals with variants in RYR1. However, recent studies have demonstrated a clinical and histopathological continuum between patients with RYR1-related congenital myopathies and those with ERM or MH susceptibility. Furthermore, animal studies have shown non-neuromuscular features such as a mild bleeding disorder and an immunological gain-of-function associated with MH/ERM related RYR1 variants raising important questions for further research. Awareness of the neuromuscular disease spectrum and potential multisystem involvement in RYR1-related MH and ERM is essential to optimize the diagnostic work-up, improve counselling and and future treatment strategies for patients affected by these conditions. This study will examine in detail the nature and severity of continuous disease manifestations and their effect on daily life in patients with RYR1-related MH and ERM.Methods:The study protocol consists of four parts; an online questionnaire study, a clinical observational study, muscle imaging, and specific immunological studies. Patients with RYR1-related MH susceptibility and ERM will be included. The imaging, immunological and clinical studies will have a cross-sectional design, while the questionnaire study will be performed three times during a year to assess disease impact, daily living activities, fatigue and pain. The imaging study consists of muscle ultrasound and whole-body magnetic resonance imaging studies. For the immunological studies, peripheral mononuclear blood cells will be isolated for in vitro stimulation with toll-like receptor ligands, to examine the role of the immune system in the pathophysiology of RYR1-related MH and ERM.Discussion:This study will increase knowledge of the full spectrum of neuromuscular and multisystem features of RYR1-related MH and ERM and will establish a well-characterized baseline cohort for future studies on RYR1-related disorders. The results of this study are expected to improve recognition of RYR1-related symptoms, counselling and a more personalized approach to patients affected by these conditions. Furthermore, results will create new insights in the role of the immune system in the pathophysiology of MH and ERM.Trial registration:This study was pre-registered at ClinicalTrials.gov (ID: {"type":"clinical-trial","attrs":{"text":"NCT04610619","term_id":"NCT04610619"}}NCT04610619).     

Literature overview highlights lack of paediatric donation protocols but identifies common themes that could guide their development

Aim

Paediatric donation is a unique and extremely sensitive process that requires specific knowledge and competencies. Most countries use protocols for organ and tissue donation to ensure optimal care for the donor and family, but these mainly focus on adults. However, the donation process for children differs from adults in many ways. An overview of the literature was performed to identify protocols for the paediatric population.

Methods

PubMed, Web of Science, EMBASE and the Internet were searched up to March 2016 for papers or other sources in English related to specific organ and tissue donation protocols for children and neonates. This comprised title, abstract and then full‐text screening of relevant data.

Results

We included 12 papers and two electronic sources that were mainly from North America and Europe. Most discussed donations after cardiac death. The recurring themes included identifying potential donors, approaching parents, palliative care and collaboration with organ procurement organisations. Most papers called for paediatric donation policies to be standardised.

Conclusion

Scientific publications in English on paediatric donation protocols are very scarce. No comprehensive paediatric donation protocol was found. We identified several recurring themes in the literature that could be used to develop such protocols.     

Prevalence and correlates of musculoskeletal disorders among Australian dental hygiene students

Abstract: Introduction: Although musculoskeletal disorders (MSD) have been identified as a significant occupational health issue for dental hygienists, few studies have explored this problem among the dental hygiene student population. Aim: The aim of this study was to investigate the prevalence and correlates of MSD among a selection of undergraduate dental hygiene students in Australia. Methodology: A self‐reporting questionnaire was distributed to dental hygiene students at an Australian university during 2008, from which a response rate of approximately 72% was achieved. Results: Musculoskeletal disorders were most commonly reported by students at the neck (64.29%), lower back (57.94%) and shoulder (48.41%) regions. Logistic regression indicated various correlations with MSD. Students who did not undertake regular exercise every week experienced an increased risk of lower back pain [Odds Ratio (OR): 4.88, 95% Confidence Interval (CI): 1.75–14.9]. Students undertaking 16–20 h of desk‐based study per week were much more likely to report neck pain (OR: 19.7, 95% CI: 1.34–378.94). Working 6–10 h on a computer each week was a risk factor for shoulder (OR: 7.03, 95% CI: 1.42–39.49) and upper back pain (OR: 5.29, 95% CI: 1.21–25.56). Conclusions: Overall, this study suggests that MSD are a reasonably common problem for dental hygiene students in Australia. As such, further studies are required to establish epidemiological patterns of MSD, and our profession will need to carefully consider preventive strategies to help minimize the impact of this important occupational health issue on the next generation of dental hygienists.     

A mouse model linking viral hepatitis and salivary gland dysfunction

Objective:  Viral hepatitis is known to cause xerostomia in humans, but this has not been reported in an animal model. We report a severe, acute, highly reproducible saliva deficiency occurring in BALB/c mice as a result of experimental viral hepatitis.
Materials and Methods:  BALB/c mice, splenectomized or carrying genetic mutations to detect immunological contributions to the saliva deficiency syndrome, were infected intraperitoneally with a non-lethal dose of murine cytomegalovirus. Pilocarpine-stimulated saliva volumes were determined between 0 and 15 days after infection. Salivary gland, liver, spleen, and sera were analyzed for the presence of virus, cytokines, inflammatory infiltrates, and tissue damage.
Results:  Saliva deficiency was detectable 2 days after cytomegalovirus infection, peaked at 88% below normal by day 7, and resolved partially in all mice by 15 days postinfection as sialoadenitis increased. Neither salivary gland viral titers, sialoadenitis, splenectomy, nor systemic inflammatory markers correlated with hyposalivation severity. Elevated liver enzymes did correlate with hyposalivation, and mice genetically resistant to murine cytomegalovirus-induced hepatitis were significantly protected.
Conclusions:  Murine cytomegalovirus-induced salivary gland dysfunction is biphasic, with an acute hepatitis-associated phase and a later sialoadenitis-associated phase. Acute murine cytomegalovirus infection of BALB/c mice may provide a model for investigation of hepatitis-associated xerostomia.