Phosphoinositides direct equine infectious anemia virus gag trafficking and release.

Phosphatidylinositol 4,5-biphosphate [PI(4,5)P(2) ], the predominant phosphoinositide (PI) on the plasma membrane, binds the matrix (MA) protein of human immunodeficiency virus type 1 (HIV-1) and equine infectious anemia virus (EIAV) with similar affinities in vitro. Interaction with PI(4,5)P(2) is critical for HIV-1 assembly on the plasma membrane. EIAV has been shown to localize in internal compartments; hence, the significance of its interaction with PI(4,5)P(2) is unclear. We therefore investigated the binding in vitro of other PIs to EIAV MA and whether intracellular association with compartments bearing these PIs was important for assembly and release of virus-like particles (VLPs) formed by Gag. In vitro, EIAV MA bound phosphatidylinositol 3-phosphate [PI(3)P] with higher affinity than PI(4,5)P(2) as revealed by nuclear magnetic resonance (NMR) spectra upon lipid titration. Gag was detected on the plasma membrane and in compartments enriched in phosphatidylinositol 3,5-biphosphate [PI(3,5)P(2) ]. Treatment of cells with YM201636, a kinase inhibitor that blocks production of PI(3,5)P(2) from PI(3)P, caused Gag to colocalize with aberrant compartments and inhibited VLP release. In contrast to HIV-1, release of EIAV VLPs was not significantly diminished by coexpression with 5-phosphatase IV, an enzyme that specifically depletes PI(4,5)P(2) from the plasma membrane. However, coexpression with synaptojanin 2, a phosphatase with broader specificity, diminished VLP production. PI-binding pocket mutations caused striking budding defects, as revealed by electron microscopy. One of the mutations also modified Gag-Gag interaction, as suggested by altered bimolecular fluorescence complementation. We conclude that PI-mediated targeting to peripheral and internal membranes is a critical factor in EIAV assembly and release.

Reflux profile of Chinese gastroesophageal reflux disease patients with combined multichannel intraluminal impedance-pH monitoring.

BACKGROUND AND AIMS: To investigate the reflux profile of Chinese gastroesophageal reflux disease (GERD) patients with the aid of combined multichannel intraluminal impedance-pH (MII-pH) monitoring technique. METHODS: Consecutive patients presented with GERD symptoms were enrolled to erosive esophagitis (EE) group, non-erosive reflux disease (NERD) group and functional heartburn (FH) group after upper endoscopy, combined MII-pH monitoring and rabeprazole test. Another 20 healthy controls (HC) were recruited. RESULTS: Sixty-four GERD patients (EE:20, NERD:22, FH:22, HC:20) were enrolled. There were more episodes of liquid reflux and proximal reflux in EE and NERD groups than that in FH and HC groups (P < 0.05). Patients in FH and HC groups had higher proportion of mixed reflux (P = 0.000). The percentage of acid reflux in EE and NERD was much higher, while there was a higher percentage of weakly acidic reflux in FH and HC (P = 0.000). No significant difference was found in MII-pH parameters between groups with and without response to rabeprazole test except recumbent percentage time of esophageal pH value below 4 and episodes of proximal reflux. CONCLUSION: Erosive esophagitis and NERD patients had more liquid and proximal reflux episodes than FH patients and healthy controls. Acid and liquid reflux was predominant in the former two groups, while weakly acidic and mixed reflux was predominant in the latter two groups.

Normal values of 24-hour combined esophageal multichannel intraluminal impedance and pH monitoring in the Chinese population.

BACKGROUND: There is a lack of data on combined esophageal multichannel intraluminal impedance and pH (MII-pH) monitoring in the Chinese population. GOALS: To define the normal range and compare the parameters to those of the Western population. STUDY: Healthy volunteers were recruited and underwent 24-hour ambulatory combined MII-pH monitoring. Gastroesophageal reflux episodes were detected and characterized by pH (acidic, weakly acidic and weakly alkaline reflux) and composition (liquid, mixed and gas reflux). RESULTS: Seventy healthy volunteers (male:female 33:37) were recruited. The median and 95th percentile number of the total reflux episodes over 24 h in the Chinese population was 40 and 75, respectively, whereas the corresponding numbers of acidic, weakly acidic and weakly alkaline reflux episodes were 22 and 54, 16 and 40, and 0 and 4, respectively. Among all reflux episodes 53.3% were acidic, 44.7% were weakly acidic, and 2% weakly alkaline. More than half (52.4%) of the reflux episodes were mixed, 37.2% were liquid, and 10.4% were gas. A total of 26.6% of reflux episodes reached 15 cm above the lower esophageal sphincter. Male gender was associated with an increased number of acid, liquid, mixed and proximal reflux episodes (p < 0.05). CONCLUSIONS: This study provides normal values for the Chinese population. Differences between genders in impedance parameters required caution during data interpretation. The number of reflux episodes in the Chinese population was similar to that in the Western population.