The accurate and prompt diagnosis of SARS-CoV-2 infection is required for the control and treatment of the coronavirus infection disease 2019 (COVID-19). In this study, we aimed to investigate the time courses of the anti-severe acute corona respiratory syndrome coronavirus 2 (SARS-CoV-2) IgM and IgG titers and to evaluate the sensitivity and specificity of such tests according to the specific day after the onset of COVID-19 among a patient population in Japan. We measured the titers of SARS-CoV-2 IgM and IgG in sera from 105 subjects, including 26 symptomatic COVID-19 patients, using chemiluminescent immunoassay (CLIA) methods utilizing magnetic beads coated with SARS-CoV-2 nucleocapsid protein and spike protein. The results of a ROC analysis suggested the possibility that the cutoff values in Japan might be lower than the manufacturer’s reported cutoff (10 AU/mL): 1 AU/mL for IgM and 5 AU/mL for IgG. The sensitivity of the test before Day 8 after symptom onset was less than 50%; at Days 9–10, however, we obtained a much higher sensitivity of 81.8% for both IgM and IgG. At 15 days or later after symptom onset, the SARS-CoV-2 IgG test had a sensitivity of 100%. These results suggest that if the number of days since disease onset is taken into consideration, these antibody tests could be very useful for the diagnosis of COVID-19 and similar diseases.
Oxidative status of albumin was not a useful biomarker for oxidative stress in practical use due to time-consuming measuring method. We evaluated oxidized, human nonmercaptalbumin measured more quickly than ever by a novel method using anion-exchange HPLC. In 60 subjects taking a general health examination, mean serum human nonmercaptalbumin level was 25.1 ± 3.0% with no gender difference but positive correlation with age. There were no links between human nonmercaptalbumin and C-reactive protein, γ-glutamyltransferase or iron, reportedly associated with oxidative stress. Human nonmercaptalbumin correlated with systolic blood pressure, pulse pressure and body mass index among physical findings. Positive correlations were observed between human nonmercaptalbumin and AST, LDH, BUN, or creatinine, suggesting that oxidative stress may link with liver injury and renal function. Human nonmercaptalbumin correlated with uric acid in female but not in male, suggesting that higher uric acid levels may be associated with increased oxidative stress only in female. As another gender difference, white blood cell counts correlated with human nonmercaptalbumin in female, while the parameters for red blood cells correlated with human nonmercaptalbumin in male. In conclusion, serum human nonmercaptalbumin level in healthy subjects was approximately 25% as previously reported. Oxidative stress may be closely associated with hypertension, obesity, liver injury, renal function, and anemia.
Objective
To investigate the oxidized albumin ratio, which is the redox ratio of human nonmercaptalbumin (HNA) to serum albumin (%HNA), as a biomarker in idiopathic Parkinson’s disease (iPD) and related neurodegenerative disorders.
Methods
This prospective study enrolled 216 iPD patients, 15 patients with autosomal recessive familial PD due to parkin mutations (PARK2), 30 multiple system atrophy (MSA) patients, 32 progressive nuclear palsy (PSP) patients, and 143 healthy controls. HNA was analyzed using modified high‐performance liquid chromatography and was evaluated alongside other parameters.
Results
iPD and PARK2 patients had a higher %HNA than controls (iPD vs. controls: odds ratio (OR) 1.325, P < 0.001; PARK2 vs. controls: OR 1.712, P < 0.001). Even iPD patients at an early Hoehn & Yahr stage (I and II) showed a higher %HNA than controls. iPD patients had a higher %HNA than MSA and PSP patients (iPD vs. MSA: OR 1.249, P < 0.001, iPD vs. PSP: OR 1.288, P < 0.05). When discriminating iPD patients from controls, %HNA corrected by age achieved an AUC of 0.750; when discriminating iPD patients from MSA and PSP patients, an AUC of 0.747 was achieved. Furthermore, uric acid, an antioxidant compound, was decreased in iPD patients, similar to the change in %HNA.
Interpretation
%HNA was significantly increased in iPD and PARK2 patients compared with controls, regardless of disease course and severity. Oxidative stress might be increased from the early stages of iPD and PARK2 and play an important role in their pathomechanisms.
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