Increase in antibody titer and change over time associated with severe acute respiratory syndrome coronavirus 2 infection after mRNA vaccination: Consideration of the significance of additional vaccination.

Key Clinical Message: Most Japanese patients naturally infected with COVID-19 were infected after mRNA vaccination, and many maintained high antibody titers due to hybrid immunity. The significance of additional vaccination in hybrid-immunized cases is highly questionable. Abstract: Spontaneous infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after mRNA vaccination causes a marked increase in antibody titer because of the combined effect of vaccine and infection ("hybrid immunity"). In this study, we discuss the significance of the mRNA vaccine booster inoculation that has been repeatedly performed in Japan. We describe the temporal trends of antibody titers in cases in which antibody titers were markedly increased by hybrid immunization. The antibody titer increased with hybrid immunization and tended to decrease with time. However, several cases maintained high antibody titers for approximately 1 year after coronavirus disease 2019 (COVID-19) diagnosis, even without booster vaccination. Most Japanese patients naturally infected with COVID-19 were infected after mRNA vaccination, and many maintained high antibody titers due to hybrid immunity. The significance of additional vaccination in hybrid-immunized cases is highly questionable regarding cost-effectiveness and risk-benefit.

Differences in serum and plasma levels of microRNAs and their time-course changes after blood collection.

Background: Serum and plasma are used for measurements of microRNAs (miRNAs) as biomarkers of various diseases. However, no consistent findings have been obtained regarding differences in serum and plasma levels of miRNAs. The purpose of this study was to clarify differences in serum and plasma levels of total miRNAs and their time-course changes after blood collection. Methods: Venous blood was collected from healthy men, and samples were prepared at the time points of 0, 15, 30, 60 and 180 min after blood collection for plasma and after clot formation for serum. Levels of total miRNAs were analyzed by the hybridization method using the 3D-Gene miRNA Oligo chip. Results: About one third of 2632 miRNAs tested showed levels high enough for comparison of serum and plasma levels and for investigation of their time-course changes. Levels of 299 miRNAs at time 0 were significantly different in serum and plasma. Levels of representative platelet-derived miRNAs including miR-185-5p, -22-3p and -320b were significantly higher in plasma than in serum, while levels of representative erythrocyte-derived miRNAs including miR-451a, -486-5p and -92a-3p were not significantly different in serum and plasma. Plasma levels of 173 miRNAs and 6 miRNAs showed significant decreasing and increasing tendencies, respectively, while there were no miRNAs in serum that showed significant time-course changes. Conclusion: The results suggest that careful attention should be paid when comparing serum and plasma levels of miRNAs and that plasma samples should be prepared early after blood collection.

Longitudinal Changes in IgG-Type SARS-CoV-2 Antibody Titers after COVID-19 Vaccination and a Prominent Increase in Antibody Titers When Infected after Vaccination.

OBJECTIVE: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody titers level and duration of elevated levels are considered important indicators for confirming the efficacy of coronavirus disease 2019 (COVID-19) vaccines. The objective of this study was to demonstrate the changes in antibody titers after the second and third doses of the COVID-19 vaccine, and to determine the antibody titers in cases of spontaneous infection with SARS-CoV-2 after vaccination. MATERIALS AND METHODS: From June 2021 to February 2023, IgG-type SARS-CoV-2 antibody titers were measured in 127 participants, including 74 outpatients and 53 members of staff, at the Osaka Dental University Hospital (64 males and 63 females, mean age 52.3 ± 19.0 years). RESULTS: Consistent with previous reports, the SARS-CoV-2 antibody titer decreased with time, not only after the second dose but also after the third dose of the vaccine if there was no spontaneous COVID-19 infection. We also confirmed that the third booster vaccination was effective in increasing the antibody titer. A total of 21 cases of natural infections were observed after administering two or more doses of the vaccine. Thirteen of these patients had post-infection antibody titers exceeding 40,000 AU/mL, and some cases continued to maintain antibody titers in the tens of thousands of AU/mL even after more than 6 months had passed since infection. CONCLUSIONS: The rise in and duration of antibody titers against SARS-CoV-2 are considered important indicators for confirming the efficacy of novel COVID-19 vaccines. A longitudinal follow-up of antibody titers after vaccination in larger studies is warranted.

Association between oral frailty and cystatin C-related indices-A questionnaire (OFI-8) study in general internal medicine practice.

BACKGROUND: Cystatin C-related indices such as the ratio of creatinine to cystatin C (Cr/CysC) and the ratio of estimated glomerular filtration rate by cystatin C (eGFRcys) to creatinine eGFRcre (eGFRcys/eGFRcre) levels have been shown to be associated with muscle mass and strength and can be markers of sarcopenia. Oral frailty is defined as an age-related gradual loss of oral functions, accompanied by a decline in cognitive and physical functions. It results in adverse health-related outcomes in older age, including mortality, physical frailty, functional disability, poor quality of life, and increased hospitalization and falls. Therefore, poor oral health among the elderly is an important health concern due to its association with the pathogenesis of systemic frailty, suggesting it to be a multidimensional geriatric syndrome. The Oral Frailty Index-8 (OFI-8) is a questionnaire that can be used for easy screening of oral frailty. This study aimed to investigate whether cystatin C- related indices are different between patients with low to moderate risk of oral frailty and those at high risk of oral frailty, using the OFI-8 in attending a general internal medicine outpatient clinic. MATERIALS AND METHODS: This is a cross-sectional study that included 251 patients with a mean age of 77.7±6.6 years and a median age of 77 years (128 men: mean age, 77.1±7.3 years; median age, 77 years and 123 women: mean age, 78.4±5.7 years; median age, 78 years) attending general internal medicine outpatient clinics. OFI-8 scores were tabulated by gender to determine whether there were differences between patients at low to moderate risk of oral frailty (OFI-8 score ≤3 points) and those at high risk (OFI-8 score ≥4 points) in Cr/CysC, eGFRcys/eGFRcre levels, height, weight, grip strength, etc. were examined. RESULTS: The OFI-8 score was higher in women than in men, suggesting that oral frailty is more common in women. Cr/CysC, eGFRcys/eGFRcre and grip strength were significantly lower in both men and women in the high-risk group for oral frailty (OFI-8 score ≥ 4). Height, hemoglobin level, red blood cell count, and serum albumin levels were significantly lower in men with an OFI-8 score ≥4. Receiver operating characteristic curve (ROC) analysis also showed that Cr/CysC and eGFRcys/eGFRcre were significantly associated with an OFI-8 score≥4 in both men and women. CONCLUSION: Cr/CysC and eGFRcys/eGFRcre were significantly lower in the high-risk group for oral frailty on the OFI-8in both men and women. A relationship exists among cystatin C-related indices, which can effectively screen systemic frailty. Similarly, the OFI-8 score can be used to effectively screen oral frailty. Thus, a collaboration that incorporates both systemic and oral frailty from medical and dental perspectives is required.

Trends in Antibody Titers after SARS-CoV-2 Vaccination-Insights from Self-Paid Tests at a General Internal Medicine Clinic.

Background: The rise in antibody titers against the novel coronavirus (SARS-CoV-2) and its duration are considered an important indicator for confirming the effect of a COVID-19 vaccine, and self-paid tests of antibody titer are conducted in many facilities nationwide. Methods: The relationship between the number of days after the second and third dose of vaccines, age, and antibody titer was determined from the medical records of general internal medicine clinics that conducted self-paid testing of the SARS-CoV-2 antibody titer using Elecsys Anti-SARS-CoV-2 S (Roche Diagnostics); the relationship between the number of days after two or more doses of vaccines and antibody titer was also determined. We also examined the antibody titers in cases of spontaneous infection with SARS-CoV-2 after two or more doses of the vaccine. Results: Log-transformed SARS-CoV-2 antibody titers measured within 1 month from the second or third dose of vaccine showed a negative correlation with age (p < 0.05). In addition, the log-transformed antibody titers also showed a negative correlation trend with the number of days after the second dose of vaccine (p = 0.055); however, there were no significant correlations between the log-transformed antibody titers and the number of days after the third dose of vaccine. The median antibody titer after the third vaccination was 18,300 U/mL, more than 10 times the median antibody titer after the second dose of vaccine, of 1185 U/mL. There were also some cases of infection after the third or fourth dose of vaccine, with antibody titers in the tens of thousands of U/ml after infection, but the patients still received further booster vaccinations after the infection. Conclusions: The antibody titers after the third vaccination did not attenuate after a short follow-up period of one month, while they tended to attenuate after the second vaccination. It is considered that many people in Japan received further booster vaccinations after spontaneous infection, even though they already had antibody titers in the tens of thousands of U/mL due to "hybrid immunity" after spontaneous infection following two or more doses of vaccine. The clinical significance of the booster vaccination in this population still needs to be thoroughly investigated and should be prioritized for those with low SARS-CoV-2 antibody titers.

Augmentation by resveratrol of the inhibitory effect of ethanol on platelet aggregation.

Ethanol and resveratrol have been shown to inhibit platelet aggregation. The aim of this study was to determine whether resveratrol has an additional effect on ethanol-induced inhibition of platelet aggregation. Ca2+ entry and subsequent aggregation of human platelets were measured by the fluorescence method and light transmittance method, respectively. Thromboxane B2 concentrations in media containing platelets were measured by using the enzyme-linked immunosorbent assay. Platelet aggregation induced by thrombin (0.025 U/ml) was significantly inhibited by preincubation of platelets with ethanol (0.5%). Preincubation with resveratrol (3.125 µM), which did not affect thrombin-induced platelet aggregation, significantly augmented the inhibitory effect of ethanol on platelet aggregation. Similar synergic effects of ethanol and resveratrol were found on aggregatory responses to collagen (2 µg/ml) and arachidonic acid (0.25 mM). On the other hand, the thrombin-induced increase in intracellular Ca2+ concentration ([Ca2+]i) was not affected by ethanol alone, resveratrol alone or both ethanol and resveratrol together. In nominally Ca2+-free medium, arachidonic acid (0.75 mM) caused a potent platelet aggregation, which was not affected by the presence of ethanol alone, resveratrol alone, or both of them together. Thromboxane B2 formation induced by thrombin was significantly inhibited by ethanol (0.5%) alone and resveratrol (3.125 µM) alone, and these inhibitory effects were significantly augmented in the presence of both ethanol and resveratrol together. Resveratrol shows an additive effect on ethanol-induced inhibition of platelet aggregation. This effect by resveratrol is partly explained by its inhibitory action on thromboxane A2 production in platelets. In addition, both ethanol and resveratrol attenuate platelet aggregation through acting on the Ca2+-dependent intra-platelet pathway after an increase in [Ca2+]i induced by thrombin.

Data on urinary pteridines as a discriminator of atherosclerotic risk in patients with diabetes.

Presented here are the supplemental data of the research article "Urinary pteridines as a discriminator of atherosclerotic risk in patients with diabetes" [1]. These data provide the first information on variables that affect urinary levels of pteridines (oxidized-form pteridine derivatives) in patients with diabetes mellitus. In linear regression analysis, gender (women vs. men), current history of smoking and urinary albumin showed significant positive correlations with pteridines, while there were significant inverse correlations of pteridines with a history of alcohol drinking and body mass index. The above associations were confirmed by using analysis of covariance and logistic regression analysis. Among the eight variables (age, gender, medication therapy for diabetes, smoking, alcohol drinking, body mass index, hemoglobin A1c and urinary albumin) tested, smoking showed the strongest association with urinary pteridines.

Urinary pteridines as a discriminator of atherosclerotic risk in patients with diabetes.

Background and aims: We have recently proposed urinary pteridine level as a useful biomarker of oxidative stress in a general population. However, the significance of urinary pteridines in patients with diabetes is unknown. Methods: The relationships of the level of urinary pteridine derivatives with d-dimer, ankle-brachial pressure index (ABI), and known cardiovascular risk factors were investigated in patients with type 2 diabetes. Results: Urinary pteridine level showed significant positive correlations with urinary15-isoprostane F2t, female gender, history of smoking and d-dimer and significant inverse correlations with history of alcohol drinking, body mass index (BMI) and ABI. ABI was significantly lower and d-dimer was significantly higher in the highest tertile group of pteridines than in the lowest tertile group. The odds ratios of the highest vs. lowest tertiles for low ABI and high d-dimer were significantly higher than the reference level. The above relationships of urinary pteridines with ABI and d-dimer were not altered when age, gender, BMI, hemoglobin A1c and history of alcohol drinking were used as explanatory variables in multivariable analyses. History of smoking confounded the relation of pteridines with ABI but not that with d-dimer. However, in logistic regression analysis, the association between pteridines and ABI remained significant with adjustment for history of smoking. Conclusion: Urinary pteridine level was associated with d-dimer and ABI, which reflect blood coagulability and arterial flow to the lower extremities, respectively, and is thus thought to be a useful discriminator of thromboatherosclerotic risk in patients with diabetes.

Resveratrol inhibits Ca2+ signals and aggregation of platelets.

BACKGROUND: Resveratrol has been shown to inhibit platelet aggregation. However, the mechanism for this action of resveratrol remains to be clarified. The purpose of this study was to elucidate the Ca2+-related mechanism for the inhibitory action of resveratrol on platelet aggregation. METHODS: Ca2+ entry and subsequent aggregation of human platelets induced by different stimulants including thrombin, thapsigargin, and 1-oleoyl-2-acetylglycerol (OAG) were measured by the fluorescence method and light transmittance method, respectively. Each stimulant was added to a nominally Ca2+-free medium containing platelets, and then CaCl2 was added to the medium to induce Ca2+ influx into platelets. RESULTS: Thapsigargin-induced Ca2+ entry into platelets and subsequent platelet aggregation were significantly inhibited in the presence of resveratrol at 6.25 µM or higher concentrations, while OAG-induced Ca2+ entry and subsequent platelet aggregation were not affected by resveratrol at concentrations up to 50 µM. In the nominally Ca2+-free medium, thrombin induced a small transient increase in intracellular Ca2+ concentrations, which was attenuated in the presence of resveratrol at 12.5 µM or higher concentrations. Thrombin-induced Ca2+ entry into platelets and subsequent platelet aggregation were significantly inhibited in the presence of resveratrol at 12.5 µM or higher concentrations. CONCLUSIONS: The results suggest that resveratrol inhibits thrombin-induced platelet aggregation through decreasing Ca2+ release from its stores and inhibiting store-operated Ca2+ influx into platelets.

Inverse association between habitual alcohol drinking and d-dimer in patients with type 2 diabetes mellitus.

Alcohol is known to inhibit blood coagulation. Patients with diabetes mellitus are prone to show hypercoagulability. However, it remains to be clarified whether and how habitual alcohol drinking affects coagulability in patients with diabetes. The purpose of this study was to determine the relationship between alcohol intake and d-dimer, a sensitive marker of blood coagulation, in patients with diabetes. We investigated the relationship between alcohol intake and d-dimer in plasma of 269 patients with type 2 diabetes by using analysis of covariance and logistic regression analysis after adjustment for age, gender, body mass index, hemoglobin A1c, and histories of smoking and anti-coagulation therapy. Log-transformed d-dimer and HDL cholesterol were significantly lower and higher, respectively, in regular drinkers than in nondrinkers, while there were no significant differences in log-transformed d-dimer and HDL cholesterol in occasional drinkers and nondrinkers. Odds ratios of regular drinkers vs. nondrinkers for high d-dimer (0.46 [0.21-0.98]) and low HDL cholesterol (0.20 [0.08-0.50]) were significantly lower than the reference level, while the odds ratios of occasional drinkers for high d-dimer (1.24 [0.41-3.73]) and low HDL cholesterol (0.43 [0.15-1.25]) were not significantly different from the reference level. HDL cholesterol showed a significant inverse correlation with log-transformed d-dimer both in overall subjects and in nondrinkers. Regular drinking, but not occasional drinking, was associated with lower d-dimer levels, suggesting that habitual alcohol drinking suppresses hypercoagulability in patients with diabetes. There is an alcohol intake-independent inverse association between HDL cholesterol and d-dimer.

Inhibition by Ethanol of Shear Stress-Induced Formation of Platelet Thrombi in Whole Blood.

AIMS: The risk of thromboatherosclerotic disease is lower in moderate drinkers than in non-drinkers. We investigated the effects of ethanol on platelet aggregation under a condition with shear stress. SHORT SUMMARY: Shear stress-induced formation of platelet thrombi is inhibited by ethanol at its attainable concentrations after drinking. This effect is prominent at the early stage of thrombus formation, being in agreement with inhibitory actions of ethanol on the initial steps of platelet activation such as Ca2+ entry and phospholipase A2 activation. METHODS: Platelet aggregation was evaluated by using a total thrombus-formation analysis system, and shear rates of 1000 s-1 (low), 1500 s-1 (middle) and 2000 s-1 (high) were loaded to whole blood. The times required to generate increases in flow pressure of 10 kPa (T10), 30 kPa (T30) and 50 kPa (T50) in microchips containing the blood, which depend on the degree of thrombus generation, were recorded. RESULTS: Under the conditions of the low-grade and middle-grade shear rates, T10 and T30 were significantly longer in the presence of ethanol at 0.25-1% than in the absence of ethanol. T10 under the condition of the low-grade shear rate and T30 under the conditions of the low-grade and middle-grade shear rates were also significantly longer in the presence of ethanol at 0.125% than in the absence of ethanol. On the other hand, T50 under the conditions of the low-grade and middle-grade shear rates was not significantly different in the absence and presence of ethanol at 0.125, 0.25 and 0.5%. Under the condition of the high-grade shear rate, T10, T30 and T50 were not significantly different in the absence and presence of ethanol at its lower concentrations. CONCLUSIONS: Ethanol at attainable concentrations inhibits platelet thrombus formation induced by shear stress, and the inhibitory effect of ethanol is prominent at the early stage of thrombus formation.