The low-pH stability discovered in neuraminidase of 1918 pandemic influenza A virus enhances virus replication.

The "Spanish" pandemic influenza A virus, which killed more than 20 million worldwide in 1918-19, is one of the serious pathogens in recorded history. Characterization of the 1918 pandemic virus reconstructed by reverse genetics showed that PB1, hemagglutinin (HA), and neuraminidase (NA) genes contributed to the viral replication and virulence of the 1918 pandemic influenza virus. However, the function of the NA gene has remained unknown.

Determination of serum glucose by horseradish peroxidase-catalysed imidazole chemiluminescence coupled to a micro-flow-injection system.

The reactivity of flow-injection (FI)-horseradish peroxidase (HRP)-catalysed imidazole chemiluminescence (CL) was studied for continuous determination of hydrogen peroxide (H(2)O(2)) and serum glucose with immobilized glucose oxidase. Light emission by the HRP-catalysed imidazole CL was obtained when immobilized HRP, alkaline imidazole (in Tricine solution, pH 9.3) and H(2)O(2) were reacted at room temperature.

Reactivation of horseradish peroxidase with imidazole for continuous determination of hydrogen peroxide using a microflow injection-chemiluminescence detection system.

A method for reactivation of inactivated horseradish peroxidase (HRP) was studied and exploited in an assay for hydrogen peroxide (H(2)O(2)). Addition of imidazole into a mobile phase made continuous determination of hydrogen peroxide (H(2)O(2)) possible by micro fl ow injection based on horseradish-catalysed luminol chemiluminescence. For reproducible determination of H(2)O(2) with HRP, the inactivation of HRP via protonation of the active sites of HRP caused by reaction with H(2)O(2) must be avoided.

[Tumor necrosis factor-alpha and interferon-gamma modulate in vitro expression of nitric oxide synthase in human nasal epithelial cells].

Background: Interest in the physiological, pathological and therapeutic implications of nitric oxide (NO) have grown exponentially, with human nasal cavity and paranasal sinuses considered a dominant source of NO, indicating that this molecule possesses the diversity of biological effects in the regulation of airway clearance and nonspecific cellular immunity. We previously observed differences in NO synthase (NOS) isoform constitutively expressed in nasal epithelial cells (NECs) from allergic and normal subjects.

Objectives: We extended the previous work to determine whether in vitro stimulation with proinflammatory cytokines influences levels of different NOS isoform expression.