Impaired humoral immunity following COVID-19 vaccination in HTLV-1 carriers.

BACKGROUND: Whether human T-lymphotropic virus type 1 (HTLV-1) carriers can develop sufficient humoral immunity after coronavirus disease 2019 (COVID-19) vaccination is unknown. METHODS: To investigate humoral immunity after COVID-19 vaccination in HTLV-1 carriers, a multicenter, prospective observational cohort study was conducted at five institutions in southwestern Japan, an endemic area for HTLV-1. HTLV-1 carriers and HTLV-1-negative controls were enrolled for this study from January to December 2022. During this period, the third dose of the COVID-19 vaccine was actively administered. HTLV-1 carriers were enrolled during outpatient visits, while HTLV-1-negative controls included health care workers and patients treated by participating institutions for diabetes, hypertension, or dyslipidemia. The main outcome was the effect of HTLV-1 infection on the plasma anti-COVID-19 spike IgG (IgG-S) titers after the third dose, assessed by multivariate linear regression with other clinical factors. RESULTS: We analyzed 181 cases (90 HTLV-1 carriers, 91 HTLV-1-negative controls) after receiving the third dose. HTLV-1 carriers were older (median age 67.0 vs. 45.0 years, p < 0.001) and more frequently had diabetes, hypertension, or dyslipidemia than did HTLV-1-negative controls (60.0% vs. 27.5%, p < 0.001). After the third dose, the IgG-S titers decreased over time in both carriers and controls. Multivariate linear regression in the entire cohort showed that time since the third dose, age, and HTLV-1 infection negatively influenced IgG-S titers. After adjusting for confounders such as age, or presence of diabetes, hypertension, or dyslipidemia between carriers and controls using the overlap weighting propensity score method, and performing weighted regression analysis in the entire cohort, both time since the third dose and HTLV-1 infection negatively influenced IgG-S titers. CONCLUSIONS: The humoral immunity after the third vaccination dose is impaired in HTLV-1 carriers; thus, customized vaccination schedules may be necessary for them.

Impaired myocardial blood flow reserve in subjects with metabolic syndrome analyzed using positron emission tomography and N-13 labeled ammonia.

PURPOSE: Coronary vasomotor response might be impaired in metabolic syndrome (MS); however, the precise abnormality has not been elucidated. The aim of this study was to assess coronary-vasomotor response in MS subjects using N-13 labeled ammonia and positron emission tomography. METHODS AND RESULTS: Myocardial blood flow (MBF) was measured at rest and during adenosine infusion in MS subjects (n = 13, MS group) with no definite evidence of heart disease and in subjects without MS (n = 14, non-MS group). Coronary vascular resistance (CVR) was calculated by dividing the mean aortic blood pressure by MBF. Myocardial blood flow reserve (MFR) was calculated as the ratio of the MBF during adenosine infusion to that during rest. Blood chemical parameters were measured to evaluate their relationship with MFR. During adenosine infusion, MBF was lower (p = 0.0085) and CVR higher (p = 0.0128) in the MS group than in the non-MS group and MFR was significantly lower in the MS group than in the non-MS group (2.13 +/- 0.99 vs. 3.38 +/- 0.95, p = 0.0027). Multivariate analysis demonstrated that the homeostasis model assessment-insulin resistance (p < 0.05) and the presence of hypertension (p < 0.05) were independent determinants of MFR. CONCLUSIONS: The results indicate that MFR was impaired in MS subjects, suggesting that an abnormal coronary microvascular response occurred in these subjects. This abnormality may have been partially due to insulin resistance and hypertension.

[Examination of bed overlaps in 18F-FDG PET/CT 3D data acquisition].

The purpose of this study was to determine the best bed overlaps in PET/CT 3D acquisition to reconstruct a transverse image with uniform quality not depending on axial slice position. First, the value of the image contrast ratio, non-uniformity (NU) value, and coefficient of variation (COV) were examined in the image of a cylindrical phantom at each slice position. The image-contrast ratio was almost constant in all slice images, and the NU value and COV were also constant in the slice images up to 13 and 19 slices from the center, respectively, but these values increased with closeness to the edge of the detector. Secondly, COV and image contrast ratios at different sizes of (18)F-FDG concentration (phi 19 mm, phi 16 mm, phi 13 mm, phi 10 mm) were examined in the case of overlapping the bed frame with 11, 15, and 21 slices in acquiring data in 3D mode. In 21 and 15 slices overlapping in acquisition, the image contrast ratios for all concentrations were greater than 0.13, which was the threshold image contrast ratio needed to identify FDG concentration from the background image with naked eye scanning under our conditions. However, in 11 slices with overlapping acquisition, the image-contrast ratio for a phi 10 mm concentration were close to or less than 0.13 in the all slice images. As a result, 15 overlapping slices was a reasonable minimum number of slices to identify a phi 10 mm (18)F-FDG concentration while maintaining the image quality in PET/CT 3D acquisition in our institution.