The Influence of Patello-Femoral Overstuffing After Modular Unlinked Bicompartmental Knee Arthroplasty (BiKA) for Medial Tibio-Femoral and Patello-Femoral Osteoarthritis of the Knee.

BACKGROUND: The factors affecting results after bicompartmental knee arthroplasty (BiKA) have not been fully elucidated. This major ligament-preserving procedure may be more susceptible to overstuffing of the patello-femoral (PF) joint than the major ligament-sacrificing total knee arthroplasty. Currently, we investigated the effect of PF overstuffing after BiKA on its clinical outcome. METHODS: There were 71 patients (74 knees) who underwent modular unlinked BiKA at our clinic who had a follow-up of 5 to 9 years. Final follow-up results were assessed by evaluating knee range of motion, the 2011 Knee Society Score (2011KSS), Japanese Knee Osteoarthritis Measure, and radiological findings. The degree of postoperative PF overstuffing was evaluated by computed tomography and magnetic resonance images for 55 knees, and the correlation between the degree of overstuffing and postoperative clinical results were examined. RESULTS: Overall clinical results improved significantly after surgery without any revision cases. The X-ray measurements showed the improved coronal alignments and the appropriate implant installation angles. Higher degree of postoperative PF overstuffing caused by insufficient amount of osteotomy on the anterior surface of the femur correlated with worse postoperative total 2011KSS at 2 years after surgery (Spearman's rank correlation coefficient (rs) = -0.387, P = .004), as opposed to no correlation at the time of the final follow-up (Spearman's rank correlation coefficient = 0.068, P = .623). CONCLUSION: Modular unlinked BiKA provided patients with a high level of satisfaction and functional improvement over 5 to 9 years postoperatively. However, because PF overstuffing affects initial patient satisfaction, the amount of osteotomy should be determined carefully during the surgery.

Endoscopic papillectomy could be rewarding to patients with early stage duodenal ampullary carcinoma?

BACKGROUND/PURPOSE: There is currently no consensus on the use of endoscopic papillectomy (EP) for early stage duodenal ampullary adenocarcinoma. This study aimed to evaluate the feasibility of EP for patients with early stage duodenal ampullary adenocarcinoma. METHODS: Patients who underwent EP for ampullary adenocarcinomas were investigated. Complete and clinical complete resection rates were evaluated. Clinical complete resection was defined as either complete resection or resection with positive or unknown margins but no cancer in the surgically resected specimen, or no recurrence on endoscopy after at least a 1-year follow-up. RESULTS: Adenocarcinoma developed in 30 patients (carcinoma in situ [Tis]: 21, mucosal tumors [T1a(M)]: 4, tumors in the sphincter of Oddi [T1a(OD)]: 5). The complete resection rate was 60.0% (18/30) (Tis: 66.7% [14/21], T1a[M]: 50.0% [2/4], and T1a[OD]: 40.0% [2/5]). The mean follow-up period was 46.8 months. The recurrence rate for all patients was 6.7% (2/30). The clinical complete resection rates of adenocarcinoma were 89.2% (25/28); rates for Tis, T1a(M), and T1a(OD) were 89.4% (17/19), 100% (4/4), and 80% (4/5), respectively. CONCLUSIONS: EP may potentially achieve clinical complete resection of early stage (Tis and T1a) duodenal ampullary adenocarcinomas.

CLPX regulates mitochondrial fatty acid ß-oxidation in liver cells.

Mitochondrial fatty acid oxidation (ß-oxidation) is an essential metabolic process for energy production in eukaryotic cells, but the regulatory mechanisms of this pathway are largely unknown. In the present study, we found that several enzymes involved in ß-oxidation are associated with CLPX, the AAA+ unfoldase that is a component of the mitochondrial matrix protease ClpXP. The suppression of CLPX expression increased ß-oxidation activity in the HepG2 cell line and in primary human hepatocytes without glucagon treatment. However, the protein levels of enzymes involved in ß-oxidation did not significantly increase in CLPX-deleted HepG2 cells (CLPX-KO cells). Coimmunoprecipitation experiments revealed that the protein level in the immunoprecipitates of each antibody changed after the treatment of WT cells with glucagon, and a part of these changes was also observed in the comparison of WT and CLPX-KO cells without glucagon treatment. Although the exogenous expression of WT or ATP-hydrolysis mutant CLPX suppressed ß-oxidation activity in CLPX-KO cells, glucagon treatment induced ß-oxidation activity only in CLPX-KO cells expressing WT CLPX. These results suggest that the dissociation of CLPX from its target proteins is essential for the induction of ß-oxidation in HepG2 cells. Moreover, specific phosphorylation of AMP-activated protein kinase and a decrease in the expression of acetyl-CoA carboxylase 2 were observed in CLPX-KO cells, suggesting that CLPX might participate in the regulation of the cytosolic signaling pathway for ß-oxidation. The mechanism for AMP-activated protein kinase phosphorylation remains elusive; however, our results uncovered the hitherto unknown role of CLPX in mitochondrial ß-oxidation in human liver cells.

Request for biliary drainage for IgG4-SC could be waived before steroid administration?

BACKGROUND: In IgG4-related sclerosing cholangitis (IgG4-SC), the necessity of biliary drainage (BD) is unclear. In this study, we aimed to retrospectively investigate the improvement of liver damage and jaundice in cases of IgG4-SC with and without BD, before starting steroids. METHODS: A total of 52 patients with IgG4-SC were investigated in the study. The study endpoints were the normalization rate of alkaline phosphatase (ALP)/total bilirubin (T-Bil) after 8 weeks of steroids, with and without BD. RESULTS: Propensity score matching was performed based on ALP and T-Bil, and 28 patients were included. There were 14 patients each in the BD and non-BD groups. Before initiation of steroids, the mean ALP in the BD group and the non-BD group was 378/461 (P = .541); the mean T-Bil was 2.5/1.8 (P = .401). Eight weeks after initiation of steroids, ALP improvement rate in the BD group/non-BD group was 69.2%/61.5% (P = 1.000), and T-Bil improvement rate was 100%/100% (P = Ns). CONCLUSIONS: Steroids for IgG4-SC could prove effective in improving liver damage and jaundice, regardless of the presence or absence of BD. BD for IgG4-SC aimed to improve jaundice may not be necessary.

Pre-emptive hydration with lactated Ringer's solution could reduce the incidence of post-endoscopic retrograde cholangiopancreatography pancreatitis in at-risk patients: Propensity score-matched analysis.

BACKGROUND/PURPOSE: This study aimed to investigate the efficacy of intensive fluid-loading therapy post-endoscopic retrograde cholangiopancreatography (ERCP) for the prevention of post-ERCP pancreatitis (PEP) in at-risk patients. METHODS: In this retrospective study, data of 1200 patients at risk for PEP were investigated. After propensity score matching, 404 patients were included in the normal (n = 202) and hydration (n = 202) groups. On the day of ERCP, patients in both groups were infused with 2000 ml/24 h of fluid before ERCP. Meanwhile, the hydration group received an additional 1000 ml/10 h of lactated Ringer's solution postoperatively. RESULTS: The incidence of PEP was lower in the hydration group (12.4%) than in the normal group (24.3%) (odds ratio [OR]: 0.44; 95% CI: 0.26-0.75, p = .003). The incidence of severe PEP was 2.0% and 6.9% in the hydration and normal groups (OR: 0.27; 95% CI: 0.09-0.84, p = .027), respectively. The incidence of fatal PEP was 0% and 2.0% in the hydration and normal groups (OR: N.A.: p = .123), respectively. CONCLUSIONS: Post-ERCP hydration may be an effective method of preventing PEP, including severe PEP, in at-risk patients.

Implantable cardioverter-defibrillator therapy after resuscitation from cardiac arrest in vasospastic angina: A retrospective study.

Patients with vasospastic angina (VSA) who are resuscitated from sudden cardiac arrest (SCA) are at a high risk of recurrent lethal arrhythmia and cardiovascular events. However, the benefit of the implantable cardioverter-defibrillator (ICD) therapy in this population has not been fully elucidated. The present study aimed to analyze the prognostic impact of ICD therapy on patients with VSA and SCA. A total of 280 patients who were resuscitated from SCA and received an ICD for secondary prophylaxis were included in the present multicenter registry. The patients were divided into two groups on the basis of the presence of VSA. The primary endpoint was a composite of all-cause death and appropriate ICD therapy (appropriate anti-tachycardia pacing and shock) for recurrent ventricular arrhythmias. Of 280 patients, 51 (18%) had VSA. Among those without VSA, ischemic cardiomyopathy was the main cause of SCA (38%), followed by non-ischemic cardiomyopathies (18%) and Brugada syndrome (7%). Twenty-three (8%) patients were dead and 72 (26%) received appropriate ICD therapy during a median follow-up period of 3.8 years. There was no significant difference in the incidence of the primary endpoint between patients with and without VSA (24% vs. 33%, p = 0.19). In a cohort of patients who received an ICD for secondary prophylaxis, long-term clinical outcomes were not different between those with VSA and those with other cardiac diseases after SCA, suggesting ICD therapy may be considered in patients with VSA and those with other etiologies who were resuscitated from SCA.

Franseen Needles May Be Promising for Improving the Sampling Adequacy of EUS-FNA for Subepithelial Lesions.

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is useful in diagnosing subepithelial lesions (SELs), and adequate tissue sampling is necessary to differentiate between benign and malignant diseases to determine therapeutic strategies. This study aimed to evaluate sampling adequacy and diagnostic performance of EUS-FNA for SELs with Franseen needles. This retrospective study enrolled 130 patients who underwent EUS-FNA with a 22-gauge needle for SELs from January 2010 to March 2021. We compared sampling adequacy and predictive factors influencing the sampling adequacy of EUS-FNA for SELs between Franseen and conventional needles. The sampling adequacy rates were 95.0% (38/40) with Franseen needles and 76.7% (69/90) with conventional needles (p = 0.011). The mean number of punctures with Franseen needles (2.80) was significantly less than that with conventional needles (3.42) (p < 0.001). In the multivariate analysis, the use of Franseen needles (p = 0.029; odds ratio [OR], 5.37; 95% confidence interval [CI], 1.18−23.36) was an independent factor influencing the sampling adequacy. Compared to conventional needles, the Franseen needle could play a vital role in accurately diagnosing SELs by yielding better sampling adequacy and reducing the number of passes.

Nanoneedle-Electrode Devices for In Vivo Recording of Extracellular Action Potentials.

Microscale needle-like electrode technologies offer in vivo extracellular recording with a high spatiotemporal resolution. Further miniaturization of needles to nanoscale minimizes tissue injuries; however, a reduced electrode area increases electrical impedance that degrades the quality of neuronal signal recording. We overcome this limitation by fabricating a 300 nm tip diameter and 200 µm long needle electrode where the amplitude gain with a high-impedance electrode (>15 MΩ, 1 kHz) was improved from 0.54 (-5.4 dB) to 0.89 (-1.0 dB) by stacking it on an amplifier module of source follower. The nanoelectrode provided the recording of both local field potential (<300 Hz) and action potential (>500 Hz) in the mouse cortex, in contrast to the electrode without the amplifier. These results suggest that microelectrodes can be further minimized by the proposed amplifier configuration for low-invasive recording and electrophysiological studies in submicron areas in tissues, such as dendrites and axons.

Large-Scale Phosphoproteomic Study of Arabidopsis Membrane Proteins Reveals Early Signaling Events in Response to Cold.

Cold stress is one of the major factors limiting global crop production. For survival at low temperatures, plants need to sense temperature changes in the surrounding environment. How plants sense and respond to the earliest drop in temperature is still not clearly understood. The plasma membrane and its adjacent extracellular and cytoplasmic sites are the first checkpoints for sensing temperature changes and the subsequent events, such as signal generation and solute transport. To understand how plants respond to early cold exposure, we used a mass spectrometry-based phosphoproteomic method to study the temporal changes in protein phosphorylation events in Arabidopsis membranes during 5 to 60 min of cold exposure. The results revealed that brief cold exposures led to rapid phosphorylation changes in the proteins involved in cellular ion homeostasis, solute and protein transport, cytoskeleton organization, vesical trafficking, protein modification, and signal transduction processes. The phosphorylation motif and kinase-substrate network analysis also revealed that multiple protein kinases, including RLKs, MAPKs, CDPKs, and their substrates, could be involved in early cold signaling. Taken together, our results provide a first look at the cold-responsive phosphoproteome changes of Arabidopsis membrane proteins that can be a significant resource to understand how plants respond to an early temperature drop.

The promoting role of lysosome-localized c-Src in autophagosome-lysosome fusion.

Src-family kinases (SFKs), such as c-Src, Lyn and Fyn, belong to non-receptor-type tyrosine kinases and play key roles in cell proliferation, adhesion, and migration. SFKs are anchored to the plasma membrane, Golgi membranes and lysosomal membranes through lipid modifications. Although the functions of SFKs being localized to the plasma membrane are intensively studied, those of SFKs being localized to organelle membranes are poorly understood. Here, we show that, among SFKs, c-Src in particular is involved in a decrease in the amount of LC3-II. c-Src and non-palmitoylated Lyn [Lyn(C3S) (cysteine-3 â†’ serine-3)], which are localized onto lysosomes, decrease the amount of LC3-II and treatment with SFK inhibitors increases the amount of LC3-II, suggesting the importance of SFKs' lysosomal localization for a change of autophagic flux in a kinase activity-dependent manner. Colocalization of LC3-II with the lysosome-associated membrane protein LAMP1 shows that lysosome-localized SFKs promote the fusion of autophagosomes with lysosomes. Lysosome-localized SFKs play a positive role in the maintenance of cell viability under starvation conditions, which is further supported by knockdown of c-Src. Therefore, our results suggest that autophagosome-lysosome fusion is promoted by lysosome-localized c-Src, leading to cell survival under starvation conditions.

Kinematics and center of axial rotation during walking after medial pivot type total knee arthroplasty.

PURPOSE: In recent years, the medial pivot (MP) type total knee arthroplasty (TKA) implant has been developed and marketed for achieving more natural kinematics with MP. However, little is known about the pivot pattern during walking after MP type TKA. This study aimed to determine the kinematics and center of axial rotation during walking after MP type TKA. METHODS: This randomized prospective study enrolled 40 patients with MP type TKA, 20 with cruciate-substituting TKA (MP-CS group), 20 with posterior-stabilized TKA (MP-PS group), and 10 healthy volunteers (control group). The kinematics and center of axial rotation during overground walking were measured by a three-dimensional motion analysis system. The six-degrees-of-freedom kinematics of the knee were calculated by the point cluster method. RESULTS: The amount of change in knee flexion in early stance phase was significantly lower in the MP-CS and MP-PS groups than in the control group. The femur showed anterior translation during early stance phase in all three groups. The median center of axial rotation in the transverse plane was predominantly on the lateral side of the knee during stance in all groups. CONCLUSIONS: Kinematics during gait are thought to be determined by physical posture, the kinetic chain during weight-bearing, and the kinematic features of adjacent structures, such as the behavior of the biarticular muscles. MP-CS and MP-PS did not necessarily induce rotational motion centered on the medial ball-in-socket component during walking; translational and lateral pivoting movements were also observed. Long-term follow-up is needed to monitor for polyethylene wear and implant loosening.

Phosphorylation of Npas4 by MAPK Regulates Reward-Related Gene Expression and Behaviors.

Dopamine (DA) activates mitogen-activated protein kinase (MAPK) via protein kinase A (PKA)/Rap1 in medium spiny neurons (MSNs) expressing the dopamine D1 receptor (D1R) in the nucleus accumbens (NAc), thereby regulating reward-related behavior. However, how MAPK regulates reward-related learning and memory through gene expression is poorly understood. Here, to identify the relevant transcriptional factors, we perform proteomic analysis using affinity beads coated with cyclic AMP response element binding protein (CREB)-binding protein (CBP), a transcriptional coactivator involved in reward-related behavior. We identify more than 400 CBP-interacting proteins, including Neuronal Per Arnt Sim domain protein 4 (Npas4). We find that MAPK phosphorylates Npas4 downstream of PKA, increasing the Npas4-CBP interaction and the transcriptional activity of Npas4 at the brain-derived neurotrophic factor (BDNF) promoter. The deletion of Npas4 in D1R-expressing MSNs impairs cocaine-induced place preference, which is rescued by Npas4-wild-type (WT), but not by a phospho-deficient Npas4 mutant. These observations suggest that MAPK phosphorylates Npas4 in D1R-MSNs and increases transcriptional activity to enhance reward-related learning and memory.

Impact of the platelet washing process on in vitro platelet properties, and the levels of soluble CD40 ligand and platelet-derived microparticles in the storage media.

BACKGROUND: A new platelet (PLT) additive solution, bicarbonated Ringer's solution supplemented with acid-citrate-dextrose Formula A, termed BRS-A, as well as a new automated closed system cell processor for washing PLTs have recently been developed. This study evaluated the in vitro properties of PLTs with the automated system versus the manual method, using the BRS-A additive solution for washing and storage. METHODS: ABO-identical apheresis PLTs in 100% plasma were pooled and split equally for control (in 100% plasma or a manual method) and test (ACP215 automated system) units. In vitro characteristics of PLTs washed with the automated system were compared to those of PLTs in 100% plasma (Study 1) or washed with a manual method (Study 2) during the 7-day storage. RESULTS: In Study 1, hypotonic shock response, aggregation response, mitochondrial membrane potential, adenosine triphosphate, and CD42b mean fluorescence intensity were comparable in the control and test groups during the 7-day storage. CD62P expression was lower in the test group than controls on Days 3 and 7. The level of platelet-derived microparticles (PDMPs) in the test group on Days 1 and 2 were higher than those in controls. In contrast, the levels of soluble CD40 ligand (sCD40L) and regulated upon activation of normal T-cell expressed and secreted (RANTES) in the test units were lower than controls. In Study 2, no significant differences were found in all in vitro properties except for PLT count and the levels of PDMPs in the test units were higher than controls during storage. CONCLUSION: Apheresis PLTs washed with the automated system using BRS-A additive solution maintained in vitro properties during storage. Washing methods influenced PDMP levels but not sCD40L and RANTES.

v-Src-driven transformation is due to chromosome abnormalities but not Src-mediated growth signaling.

v-Src is the first identified oncogene product and has a strong tyrosine kinase activity. Much of the literature indicates that v-Src expression induces anchorage-independent and infinite cell proliferation through continuous stimulation of growth signaling by v-Src activity. Although all of v-Src-expressing cells are supposed to form transformed colonies, low frequencies of v-Src-induced colony formation have been observed so far. Using cells that exhibit high expression efficiencies of inducible v-Src, we show that v-Src expression causes cell-cycle arrest through p21 up-regulation despite ERK activation. v-Src expression also induces chromosome abnormalities and unexpected suppression of v-Src expression, leading to p21 down-regulation and ERK inactivation. Importantly, among v-Src-suppressed cells, only a limited number of cells gain the ability to re-proliferate and form transformed colonies. Our findings provide the first evidence that v-Src-driven transformation is attributed to chromosome abnormalities, but not continuous stimulation of growth signaling, possibly through stochastic genetic alterations.

Storage of washed platelets in BRS-A platelet additive solutions based on two types of clinically available bicarbonated Ringer's solutions with different electrolyte concentrations.

BACKGROUND: In Japan, no platelet (PLT) additive solutions (PASs) are officially approved for clinical use although blood centers often receive requests for washed PLTs to reduce adverse reactions. Recently, we developed a novel PAS called BRS-A based on clinically available bicarbonated Ringer's solution (BRS), Bicanate and acid-citrate-dextrose formula A (ACD-A), which has been shown to maintain the in vitro properties of PLTs in the condition of <5% residual plasma during 7-day storage. The aim of this study was to evaluate whether another clinically available BRS, Bicarbon with different electrolyte concentrations can be used as a PAS. STUDY DESIGN AND METHODS: Two types of BRS-As were prepared by adding 25 mL of ACD-A to 500 mL of Bicanate or Bicarbon BRSs. Bicanate-based BRS-A and Bicarbon-based BRS-A contain 0.9 or 0.5 mmol/L of magnesium chloride, 95.2 or 100.1 mmol/L of sodium chloride, 4.2 or 5.1 mmol/L of trisodium citrate, and 26.6 or 23.8 mmol/L of sodium bicarbonate, respectively; the other components were identical. Apheresis PLTs stored in these solutions with less than 5% plasma for 7-day storage were compared with regard to their in vitro properties. RESULTS: The pH levels of all units were above 7 throughout storage. The mean PLT volume, hypotonic shock response, glucose consumption, lactate production, swirling, and CD62P and CD42b expression were similar during 7-day storage. The bicarbonate levels in Bicarbon-based BRS-A were lower than those in Bicanate-based BRS-A. CONCLUSION: Differences in concentrations of electrolytes such as magnesium, sodium, citrate, and bicarbonate salts in BRS-A do not affect the in vitro properties of PLTs during 7-day storage. These results indicate that the use of another type of BRS-A based on Bicarbon as a PAS is feasible. Thus, BRS-A can be used in hospitals that do not stock Bicanate but have Bicarbon.

Establishment of culture systems for Genotypes 3 and 4 hepatitis E virus (HEV) obtained from human blood and application of HEV inactivation using a pathogen reduction technology system.

BACKGROUND: It has been demonstrated that the hepatitis E virus (HEV) can be transmitted via blood transfusion, and the risk of HEV transmission via transfusion has become a major global concern. An HEV culture system for blood-derived HEV has been sought to obtain valuable knowledge of the virus and the risk of HEV infection through blood products. STUDY DESIGN AND METHODS: We endeavored to establish an HEV culture system using RNA-positive blood specimens for Genotypes (G) 3 and 4 and applied this system to evaluate tissue culture infectious dose (TCID). We applied this method to investigate the potential of the Mirasol pathogen reduction technology (PRT) system (Terumo BCT) to inactivate live HEV in contaminated platelet samples (PLTs). PLTs were spiked with cultured HEV G3 or G4 and then treated with the Mirasol PRT system. PLTs were examined before and after the treatment for HEV load using TCID titration. RESULTS: We successfully established two strains for HEV production: the JRC-HE3 strain for G3 and the UA1 strain for G4. The Mirasol PRT system expressed more than 3 log inactivation for JRC-HE3 and more than 2 log inactivation for UA1. CONCLUSION: The Mirasol PRT system inactivated greater than 2 to 3 logs of live HEV in PLTs and can potentially be used to lower the possibility of blood-borne HEV transmission. The G3 and G4 HEV inocula identified in this study and the hepatoma cell culture system provide a new means to assess HEV infectious titer and to evaluate other pathogen reduction strategies.

Cytomegalovirus (CMV) seroprevalence in Japanese blood donors and high detection frequency of CMV DNA in elderly donors.

BACKGROUND: The current prevalence of cytomegalovirus (CMV) in Japan and the risk of CMV transfusion transmission are unknown in the era of seronegative leukoreduced blood components. STUDY DESIGN AND METHODS: We measured CMV-specific immunoglobulin (Ig)M and IgG in 2400 samples of whole blood collected from 12 groups of blood donors categorized by sex and age at 10-year intervals from their teens to their 60s. We also tested for CMV DNA using polymerase chain reaction in the cellular fractions of all samples. RESULTS: We found that 76.6% of blood donors were CMV seropositive. The seroprevalences among donors in their 20s and 30s were 58.3 and 73.3%, respectively. We detected CMV DNA in the cellular fraction of 4.3% of samples from donors in their 60s and in 1.0% of samples from donors younger than 60 years. None of the 562 seronegative samples was DNA positive. Furthermore, 14% of DNA-positive samples also contained DNA in the plasma fraction, and two of five such samples were derived from donors in their 60s. Leukoreduced plasma components derived from donations with CMV DNA in plasma samples also contained a relevant amount of CMV DNA. CONCLUSION: The seroprevalence of CMV among Japanese blood donors of child-bearing age has not changed over the past 15 years. Latent CMV becomes reactivated more frequently among elderly donors than among younger donors. A proportion of them have free CMV DNA in their plasma fraction, which could not be diminished by leukoreduction. The risk of transfusion-transmitted CMV infection in blood with plasma CMV DNA should be determined.

Age- and gender-specific distributions of hepatitis B virus (HBV) genotypes in Japanese HBV-positive blood donors.

BACKGROUND: There are an increasing number of reports on the hepatitis B virus (HBV) genotype distribution in acute or chronic HBV-infected patients in Japan; however, reports on the HBV genotype of blood donors are few. To compare the HBV genotypes of hepatitis B surface antigen (HBsAg)-positive blood donors with infected patients, all the HBsAg-positive donors' genotypes were determined. STUDY DESIGN AND METHODS: Data on Japanese blood donors from October 2006 to September 2007 were obtained from the Japanese Red Cross database. The number of available samples was 1979, and the HBV genotypes were determined in 1887 samples. The six major genotypes of HBV (A-F) were determined by enzyme-linked immunosorbent assay. The presence of the immunoglobulin M (IgM) antibody against the HBV core antigen was determined by enzyme immunoassay among all HBsAg-positive donors. RESULTS: A significant difference in the HBV genotype distribution between donors and patients was in the C/B genotype ratio. The ratios were low in blood donors (2.0-3.9) and high in patients (5.3-18.2). The genotype B ratio increases from 13.8% in teenage donors to 42.4% in those in their 50s; however; the genotype C ratio decreases from 83.1% in teenage donors to 55.1% in those in their 50s. In both IgM antibody against hepatitis B core antigen and nucleic acid test-positive donors, genotypes A and B were restricted to male donors. CONCLUSIONS: The age-specific distribution of HBV genotypes in Japanese blood donors was observed in the B/C genotype ratio. The gender-specific distribution of HBV genotype A, which originated from the US or Western countries, was observed in male Japanese donors.