Ghrelin contributes to derangements of glucose metabolism induced by rapamycin in mice

AIMS/HYPOTHESIS

Rapamycin impairs glucose tolerance and insulin sensitivity. Our previous study demonstrated that rapamycin significantly increases the production of gastric ghrelin, which is critical in the regulation of glucose metabolism. Here, we investigated whether ghrelin contributes to derangements of glucose metabolism induced by rapamycin.

METHODS

The effects of rapamycin on glucose metabolism were examined in mice receiving ghrelin receptor antagonist or with Ghsr1a gene knockout. Changes in GLUT4, c-Jun N-terminal kinase (JNK) and phosphorylated ribosomal protein S6 (pS6) were investigated by immunofluorescent staining or western blotting. Related hormones were detected by radioimmunoassay kits.

RESULTS

Rapamycin impaired glucose metabolism and insulin sensitivity not only in normal C57BL/6J mice but also in both obese mice induced by a high fat diet and db/db mice. This was accompanied by elevation of plasma acylated ghrelin. Rapamycin significantly increased the levels of plasma acylated ghrelin in normal C57BL/6J mice, high-fat-diet-induced obese mice and db/db mice. Elevation in plasma acylated ghrelin and derangements of glucose metabolism upon administration of rapamycin were significantly correlated. The deterioration in glucose homeostasis induced by rapamycin was blocked by D: -Lys3-GHRP-6, a ghrelin receptor antagonist, or by deletion of the Ghsr1a gene. Ghrelin receptor antagonism and Ghsr1a knockout blocked the upregulation of JNK activity and downregulation of GLUT4 levels and translocation in the gastrocnemius muscle induced by rapamycin.

CONCLUSIONS/INTERPRETATION

The current study demonstrates that ghrelin contributes to derangements of glucose metabolism induced by rapamycin via altering the content and translocation of GLUT4 in muscles.

Analgesic properties of loperamide differ following systemic and local administration to rats after spinal nerve injury

BACKGROUND

The analgesic properties and mechanisms of loperamide hydrochloride, a peripherally acting opioid receptor agonist, in neuropathic pain warrant further investigation.

METHODS

We examined the effects of systemic or local administration of loperamide on heat and mechanical hyperalgesia in rats after an L5 spinal nerve ligation (SNL).

RESULTS

 (1) Systemic loperamide (0.3-10 mg/kg, subcutaneous in the back) dose dependently reversed heat hyperalgesia in SNL rats, but did not produce thermal analgesia. Systemic loperamide (3 mg/kg) did not induce thermal antinociception in naïve rats; (2) systemic loperamide-induced anti-heat hyperalgesia was blocked by pretreatment with intraperitoneal naloxone methiodide (5 mg/kg), but not by intraperitoneal naltrindole (5 mg/kg) or intrathecal naltrexone (20 μg/10 μL); (3) local administration of loperamide (150 μg), but not vehicle, into plantar or dorsal hind paw tissue induced thermal analgesia in SNL rats and thermal antinociception in naïve rats; (4) the analgesic effect of intraplantar loperamide (150 μg/15 μL) in SNL rats at 45 min, but not 10 min, post-injection was blocked by pretreatment with an intraplantar injection of naltrexone (75 μg/10 μL); (5) systemic (3.0 mg/kg) and local (150 μg) loperamide reduced the exaggerated duration of hind paw elevation to noxious pinprick stimuli in SNL rats. Intraplantar injection of loperamide also decreased the frequency of pinprick-evoked response in naïve rats.

CONCLUSIONS

These findings suggest that both systemic and local administration of loperamide induce an opioid receptor-dependent inhibition of heat and mechanical hyperalgesia in nerve-injured rats, but that local paw administration of loperamide also induces thermal and mechanical antinociception.

Role of ultrasound in the assessment of benignity and malignancy of parotid masses

OBJECTIVES

This study aimed to investigate the value of ultrasound in the identification of benign and malignant parotid masses.

METHODS

Data of 189 patients with parotid gland masses undergoing ultrasound-guided fine-needle aspiration (FNA), core biopsy or surgery were reviewed retrospectively and the presumed sonographic diagnoses were compared with the histopathology. The sensitivity, specificity and accuracy of sonographic diagnoses were assessed and the sonographic characteristics of those lesions, including shape, margin, echogenicity, echotexture and vascularization, were studied.

RESULTS

Of the 189 patients, the final pathological diagnosis included 18 malignant tumours and 171 benign masses; the presumed sonographic diagnoses showed 165 cases as benign and probably benign masses (11 cases were confirmed malignant, 154 cases benign) and 24 cases were diagnosed as probably malignant and malignant masses (7 cases were confirmed malignant, 17 cases benign). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ultrasound for the diagnosis of parotid gland masses were 38.9%, 90.1%, 29.2%, 93.3% and 85.2%, respectively, and accuracy for malignant masses was 20%. The sonographic characteristics of parotid masses between benign and malignant lesions had no significant differences. The parotid gland masses in this study included pleomorphic adenoma, Warthin's tumour, retention cyst, haemangiomas, chronic granuloma, lymphoma, fibrolipoma, abscess, basal cell adenoma, oncocytoma, lymphatic tuberculosis, myoepithelioma, neurilemmoma, mucoepidermoid carcinoma, adenoid cystic carcinoma, alveolar soft part sarcoma and retinal blastoma (metastasis).

CONCLUSIONS

It is challenging to use sonography for differentiating between benign and malignant parotid gland masses. To make a definite diagnosis, ultrasound-guided FNA or core biopsy is advocated.

Quantum control of the spin-orbit interaction using the Autler-Townes effect

We have demonstrated quantum control of the spin-orbit interaction based on the Autler-Townes (ac-Stark) effect in a molecular system using a cw optical field. We show that the enhancement of the spin-orbit interaction between a pair of weakly interacting singlet-triplet rovibrational levels, G (1)Π(g)(v=12,J=21,f)-1 (3)Σ(g)(-)(v=1,N=21,f), separated by 750 MHz in the lithium dimer, depends on the Rabi frequency (laser power) of the control laser. The increase in the spin-orbit interaction due to the control field is observed as a change in the spin character of the individual components of the perturbed pair.

Benefits of pulsatile flow in pediatric cardiopulmonary bypass procedures: from conception to conduction

This review on the benefits of pulsatile flow includes not only experimental and clinical data, but also attempts to further illuminate the major factors as to why this debate has continued during the past 55 years. Every single component of the cardiopulmonary bypass (CPB) circuitry is equally important for generating adequate quality of pulsatility, not only the pump. Therefore, translational research is a necessity to select the best components for the circuit. Generation of pulsatile flow depends on an energy gradient; precise quantification in terms of hemodynamic energy levels is, therefore, a necessity, not an option. Comparisons between perfusion modes should be done after these basic steps have been taken. We have also included experimental and clinical data for direct comparisons between the perfusion modes. In addition, we included several suggestions for future clinical trials for other interested investigators.

Simvastatin exerts favourable effects on neointimal formation in a mouse model of vein graft

BACKGROUND

Simvastatin inhibits human saphenous vein neointima formation in human saphenous vein organ cultures. However, it is not known if simvastatin actually inhibits vein graft intima hyperplasia in vivo, and the underlying mechanisms behind that. In this study, we used a murine vein graft model to address these issues.

METHODS AND RESULTS

Vein grafting was performed among C57BL/6 J mice treated with low-dose (2 mg kg(-1)) or high-dose (20 mg kg(-1)) simvastatin or vehicle subcutaneously 72 h before and then daily after surgery. As compared to the vehicle, simvastatin dose-dependently significantly inhibited vein graft intima hyperplasia 4 weeks after surgeries. Immunohistochemistry studies suggested that vein graft neointima was mainly composed of vascular smooth muscle cells (VSMCs), and the rate of proliferating cell nuclear antigen (PCNA)-positive cells in the intima of vein grafts was significantly lower in simvastatin-treated groups than in control group. We isolated VSMC from mouse vena cava, simvastatin significantly reduced VSMC proliferation, and platelet-derived growth factor (PDGF)-induced VSMC migration in a dose-dependent manner.

CONCLUSION

Simvastatin inhibits neointima formation of mouse vein graft under normocholesterolaemic condition in vivo, the mechanisms might be associated with inhibitory effects of simvastatin on VSMC proliferation and migration.

3D visualization of subcellular structures of Schizosaccharomyces pombe by hard X-ray tomography

Cellular structures of the fission yeast, Schizosaccharomyces pombe, were examined by using hard X-ray tomography. Since cells are nearly transparent to hard X-rays, Zernike phase contrast and heavy metal staining were introduced to improve image contrast. Through using such methods, images taken at 8 keV displayed sufficient contrast for observing cellular structures. The cell wall, the intracellular organelles and the entire structural organization of the whole cells were visualized in three-dimensional at a resolution better than 100 nm. Comparison between phase contrast and absorption contrast was also made, indicating the obvious advantage of phase contrast for cellular imaging at this energy. Our results demonstrate that hard X-ray tomography with Zernike phase contrast is suitable for cellular imaging. Its unique abilities make it have potential to become a useful tool for revealing structural information from cells, especially thick eukaryotic cells.

Establishment of an H6N2 influenza virus lineage in domestic ducks in southern China

Multiple reassortment events between different subtypes of endemic avian influenza viruses have increased the genomic diversity of influenza viruses circulating in poultry in southern China. Gene exchange from the natural gene pool to poultry has contributed to this increase in genetic diversity. However, the role of domestic ducks as an interface between the natural gene pool and terrestrial poultry in the influenza virus ecosystem has not been fully characterized. Here we phylogenetically and antigenically analyzed 170 H6 viruses isolated from domestic ducks from 2000 to 2005 in southern China, which contains the largest population of domestic ducks in the world. Three distinct hemagglutinin lineages were identified. Group I contained the majority of isolates with a single internal gene complex and was endemic in domestic ducks in Guangdong from the late 1990s onward. Group II was derived from reassortment events in which the surface genes of group I viruses were replaced with novel H6 and N2 genes. Group III represented H6 viruses that undergo frequent reassortment with multiple virus subtypes from the natural gene pool. Surprisingly, H6 viruses endemic in domestic ducks and terrestrial poultry seldom reassort, but gene exchanges between viruses from domestic ducks and migratory ducks occurred throughout the surveillance period. These findings suggest that domestic ducks in southern China mediate the interaction of viruses between different gene pools and facilitate the generation of novel influenza virus variants circulating in poultry.

Reassortment of pandemic H1N1/2009 influenza A virus in swine

The emergence of pandemic H1N1/2009 influenza demonstrated that pandemic viruses could be generated in swine. Subsequent reintroduction of H1N1/2009 to swine has occurred in multiple countries. Through systematic surveillance of influenza viruses in swine from a Hong Kong abattoir, we characterize a reassortant progeny of H1N1/2009 with swine viruses. Swine experimentally infected with this reassortant developed mild illness and transmitted infection to contact animals. Continued reassortment of H1N1/2009 with swine influenza viruses could produce variants with transmissibility and altered virulence for humans. Global systematic surveillance of influenza viruses in swine is warranted.

Long pulse gastric electrical stimulation induces regeneration of myenteric plexus synaptic vesicles in diabetic rats

BACKGROUND

Gastric electrical stimulation (GES) may improve delayed gastric emptying in diabetic gastroparesis, but whether enteric nervous system (ENS) is directly involved in its mechanism of improvement in gastric motility is unclear. The aims were to investigate the correlation between the changes in ENS and effects of long pulse GES on them in diabetic rats induced by streptozotocin (STZ).

METHODS

Electron microscopy, immunohistochemistry, RT-PCR and western blot were used to evaluate changes of myenteric plexus neurons and synaptic vesicles in different stages of the diabetic rats. The effects of GES were detected by same methods after pacing wires were implanted and then diabetes was induced and followed by long pulse GES.

KEY RESULTS

Since 6 weeks after STZ injection, the nerve fibres were incompact and synaptic vesicles in myenteric neurons reduced. Furthermore, the myenteric neurons showed severe damage such as partial depletion of the axon, swelling of mitochondria and seriously decreased synaptic vesicles in 12 weeks after STZ injection. The synaptophysin and PGP9.5-positive area and expressions of synaptophysin mRNA and protein decreased with the duration of diabetes. Long pulse GES could induce increase of myenteric neuronal synaptic vesicles, synaptophysin and PGP9.5-positive area and in myenteric plexus. The synaptophysin mRNA and protein expression rose after GES, whatever GES beginning early or late, short-term or long-term.

CONCLUSIONS & INFERENCES

The longer duration of diabetes, the more significant damages to myenteric neurons and synaptic vesicles of diabetic rats; long pulse GES could induce regeneration of myenteric plexus synaptic vesicles, thereby reform gastric motility.