Clinical significance of a highly sensitive enzyme immunoassay of hepatitis B surface antigen using a novel electron spin resonance technique

Electron Paramagnetic Resonance Measurements of Reactive Oxygen Species by Cyclic Hydroxylamine Spin Probes

SIGNIFICANCE

Oxidative stress contributes to numerous pathophysiological conditions such as development of cancer, neurodegenerative, and cardiovascular diseases. A variety of measurements of oxidative stress markers in biological systems have been developed; however, many of these methods are not specific, can produce artifacts, and do not directly detect the free radicals and reactive oxygen species (ROS) that cause oxidative stress. Electron paramagnetic resonance (EPR) is a unique tool that allows direct measurements of free radical species. Cyclic hydroxylamines are useful and convenient molecular probes that readily react with ROS to produce stable nitroxide radicals, which can be quantitatively measured by EPR. In this work, we critically review recent applications of various cyclic hydroxylamine spin probes in biology to study oxidative stress, their advantages, and the shortcomings. Recent Advances: In the past decade, a number of new cyclic hydroxylamine spin probes have been developed and their successful application for ROS measurement using EPR has been published. These new state-of-the-art methods provide improved selectivity and sensitivity for in vitro and in vivo studies.

CRITICAL ISSUES

Although cyclic hydroxylamine spin probes EPR application has been previously described, there has been lack of translation of these new methods into biomedical research, limiting their widespread use. This work summarizes "best practice" in applications of cyclic hydroxylamine spin probes to assist with EPR studies of oxidative stress.

FUTURE DIRECTIONS

Additional studies to advance hydroxylamine spin probes from the "basic science" to biomedical applications are needed and could lead to better understanding of pathological conditions associated with oxidative stress. Antioxid. Redox Signal. 28, 1433-1443.

What can be revealed by extending the sensitivity of HBsAg detection to below the present limit?

BACKGROUND/AIMS

We investigated what can be revealed by extending the sensitivity of HBsAg detection to below the present limit.

METHODS

We examined the sensitivity of this immunoassay in comparison with real-time PCR detection of HBV DNA using serially diluted sera from HBV carriers. Low HBsAg was measured in 210 healthy volunteers and 368 patients with non-B chronic liver diseases who were negative for HBsAg by a standard EIA method.

RESULTS

The radical immunoassay was able to detect HBsAg at a concentration of 0.025 ng/ml. Low HBsAg was positive in 6 of 210 normal volunteers (2.86%), 5 of 65 non-B, non-C cirrhosis patients (7.69%), 6 of 62 non-B, non-C hepatocellular carcinoma patients (9.68%: p=0.04 vs. volunteers), 12 of 134 chronic hepatitis C patients (8.96%: p<0.02 vs. volunteers), and 11 of 107 hepatocellular carcinoma patients complicated by chronic hepatitis C (10.28%: p<0.008 vs. volunteers). Although no HBV DNA was positive in healthy volunteers, 9 patients with non-B chronic liver diseases were positive for HBV DNA by real-time PCR analysis.

CONCLUSIONS

Increasing the sensitivity of HBsAg detection to below the present limit has revealed that infection with HBV, including occult HBV, is far more endemic than suspected previously.

Relationship between airborne Cry j 1 and the onset time of the symptoms of Japanese cedar pollinosis patients

BACKGROUND

Some patients with Japanese cedar (JC) pollinosis already show pollinosis symptoms before the first day of the pollen season as determined by microscopic pollen counts.

METHODS

Airborne pollen allergen (Cry j 1) levels were measured by electron spin resonance radical immunoassay, a highly-sensitive method for Cry j 1 with a sensitivity 10-100-fold higher than conventional enzyme-linked immunosorbent assay. The symptom data from patients with JC pollinosis were collected from a mobile phone site, "pollen check sheet", and the onset times of the patients' symptoms were analyzed.

RESULTS

The relationship between airborne Cry j 1 levels and the onset time of pollinosis symptoms was investigated. The symptoms of some patients began at the time airborne Cry j 1 levels fluctuated at 1 to 3 pg/m3 and symptom scores increased at the time of sudden increase in Cry j 1 levels. About 40% of patients began to show symptoms until the first day of the pollen season and the time nearly corresponds to the time of sudden increase in Cry j 1 levels.

CONCLUSIONS

Pollinosis symptoms of some patients began at the time airborne Cry j 1 levels fluctuated at 1 to 3 pg/m3 and symptom scores increased at the time of sudden increase in Cry j 1 levels. The latter time nearly corresponds to the first day of the pollen season.