Re-evaluation of the diagnostic value of fractional exhaled nitric oxide & its impact in patients with asthma

Background & objectives: The diagnostic value of fractional exhaled nitric oxide (FeNO) in patients with asthma remains controversial. This study was aimed to re-evaluate the diagnostic value of FeNO in specific groups with asthma and identify potential factors associated with FeNO. Methods: FeNO measurement and bronchial provocation test (BPT) or bronchodilator test (BDT) were performed in patients with suggestive symptoms for asthma. Correlation analysis was performed, and receiver-operating characteristic (ROC) curves and area under the curve (AUC) were calculated to evaluate the accuracy of FeNO in diagnosis. Results: A total of 265 (66.3%) patients with asthma were identified in 400 individuals suspected to have asthma from October 2014 to June 2015. Positive correlations of gender (r=0.138, P=0.005), atopy (r=0.598, P <0.001) and rhinitis (r=0.485, P <0.001) but negative correlations of age (r=?0.220, P <0.001) and the cumulative methacholine dosage with a 20 per cent decrease in forced expiratory volume in one second (r=?0.197, P <0.001) with FeNO were found. AUC of FeNO in whole population and patients with atopy and rhinitis was 0.728 [95% confidence interval (CI) 0.675-0.781, P <0.001] and 0.752 (95% CI 0.640-0.865, P <0.001), while the cut-offs were 23.5 and 44.5 parts per billion (ppb), respectively, rendering sensitivities, specificities, positive predictive value and negative predictive value of 79.9, 54.7, 77.9, 58.1 and 78.7, 67.9, 89.2 and 48.7 per cent, respectively. The cut-off of FeNO with specificity of 90 per cent (FeNO90) for all patients and a sub-group of patients with atopy and rhinitis was 59.5 and 90.5 ppb, respectively, while FeNO90decreased by 12 ppb with every 10 years. Interpretation & conclusions: Our findings show that the diagnostic value of FeNO varies in different groups of patients with asthma, thus, the cut-off point should be adjusted in different asthmatic sub-populations. A cut-off point of FeNO with a specificity >90 per cent could decrease the false-positive rate.

Study on detecting antibodies to Toxoplasma gondii in pooled serum of blood donors by Dot-IGSS.

To prevent post-transfusion toxoplasmosis, the sera of blood donors, per six of which were mixed as a pool, were examined for anti-Toxoplasma gondii antibiodies by Dot-immunogold silver staining (Dot-IGSS) with the single serum specimens examined simultaneously. The results showed that the sensitivity and specificity of serum pool method were 92.31% and 99.96% respectively. The consistent rate between the two methods was 99.73% and kappa value was 0.947 (p<0.01). Considering the mean infection rate of Toxoplasma gondii being 4.86% in China, if the serum pool method be adoped, with pool size k=5, a 57% reduction in the number of tests, as well as the cost of the screen, can be expected. Beside the social benefit, consequent upon the interruption of the Toxoplasma gondii infection spread through blood transfusion also can be expected.

Combinations of three immunological assays for detecting anti-Toxoplasma IgG in the sera of patients infected with Toxoplasma gondii.

Enzyme-linked immunosorbent assay (ELISA), Dot-ELISA and Dot-immunogold silver staining (Dot-IGSS) were simultaneously used to detect the specific IgG against Toxoplasma gondii in 65 patients infected with the protozoa. The positive rates were 86.51%, 92.51% and 98.64%, respectively. When ELISA and Dot-ELISA results were put together, the positive rate increased to 95.38%. When Dot-IGSS results were combined with those of ELISA or Dot-ELISA, the positive rate was raised to 100%. The difference in positive rate between ELISA and Dot-IGSS was significant (x2 = 6.93, p < 0.01), but no statistically significant differences were found between ELISA and Dot-ELISA or between Dot-ELISA and Dot-IGSS. Paired comparison of the reacting intensities of the sera in the 3 assays showed the correlations were highly significant (p < 0.001), with r = 0.608 between Dot-IGSS and Dot-ELISA, r = 0.8194 between Dot-IGSS and ELISA and r = 0.517 between Dot-ELISA and ELISA. Hence combination of different serological assays may increase their sensitivity and specificity for detecting the anti-Toxoplasma antibodies.

Comparative study of Dot-immunogold silver staining and Dot-ELISA for the detection of serum antibodies against Wuchereria bancrofti.

Dot-immunogold silver staining (Dot-IGSS) and Dot-ELISA, using the soluble antigen of Brugia malayi, were employed to detect anti-Wuchereria bancrofti antibodies in 50 cases of Wuchereria bancrofti microfilaremia. The positive rates were 100% and 90% in Dot-IGSS and Dot-ELISA respectively. The average titer in the 45 positive cases was 1:184 (1:10-1:2560) for Dot-IGSS and 1:150 (1:10-1:2560) for Dot-ELISA, with 30 cases showing the same titer in both tests, 13 cases showing higher titer in Dot-IGSS than in Dot-ELISA and 2 cases in the former showing lower titers than in the latter. There was a linear relationship between the titers of antibodies detected by Dot-IGSS and by Dot-ELISA (r = 0.8443). Dot-IGSS, similar to Dot-ELISA, is easy to carry out and the result is easy to read. It is seen that Dot-IGSS is highly sensitive and specific and is practicable for immunodiagnosis and surveillance of filariasis.

The use of dot-immunogold-silver staining (dot-IGSS), dot-ELISA and dot-IGSS to detect serum antibodies from clonorchiasis patients: a comparative study.

We report the use of immunogold-silver staining (IGSS), dot-ELISA and dot-IGSS methods in the study of clonorchiasis in China. These methods were employed to detect the antibody in sera from 40 clonorchiasis patients. The positive rates were 100%, 90.0% and 95.0%, respectively. When the three methods were used to examine 40 normal sera, the negative rates were 100%, 97.5% and 97.5%, respectively. These results suggest that IGSS, dot-ELISA and dot-IGSS are highly specific and sensitive in detecting anti-Clonorchis antibody in patients.