Biomedical subjects

Masatoshi Fujita

Publications and source records attributed to Masatoshi Fujita.

At least 19 recordsLinked to original sources

PubMed2007

Sustained-release erythropoietin ameliorates cardiac function in infarcted rat-heart without inducing polycythemia.

BACKGROUND: The usefulness of sustained-release erythropoietin for improving left ventricular (LV) function without polycythemia was evaluated in a rat chronic myocardial infarction model. METHODS AND RESULTS: Four weeks after left coronary artery ligation, 50 Sprague-Dawley rats were assigned to 5 groups (n=10, each). Control group had a gelatin sheet (20x20 mm) containing saline applied to the infarct area, whereas the 4 treatment groups had gelatin sheets incorporating erythropoietin 0.1 U, 1 U, 10 U and 100 U, respectively. Endpoint measurements performed at 8 weeks after the coronary ligation revealed that the fractional area change was larger for erythropoietin 1 U and 10 U than in the other 3 groups. The LV end-systolic elastance and the time constant of isovolumic relaxation were better for erythropoietin 1 U and 10 U than in the other 3 groups. The density of vessels larger than 50 microm in diameter was the highest in the erythropoietin 1 U group. The number of red blood cells was significantly increased in groups receiving erythropoietin 10 U and 100 U. CONCLUSIONS: Gelatin hydrogel sheets incorporating 1 U erythropoietin improved LV function without inducing polycythemia in a rat chronic myocardial infarction model.

Animals↗

PubMed2006

E6AP-dependent degradation of DLG4/PSD95 by high-risk human papillomavirus type 18 E6 protein.

In most cervical cancers, DNAs of high-risk mucosotropic human papillomaviruses (HPVs), such as types 16 and 18, are maintained so as to express two viral proteins, E6 and E7, suggesting that they play important roles in carcinogenesis. The carboxy-terminal PDZ domain-binding motif of the E6 proteins is in fact essential for transformation of rodent cells and induction of hyperplasia in E6-transgenic mouse skin. To date, seven PDZ domain-containing proteins, including DLG1/hDLG, which is a human homologue of the Drosophila discs large tumor suppressor (Dlg), have been identified as targets of high-risk HPV E6 proteins. Here, we describe DLG4/PSD95, another human homologue of Dlg, as a novel E6 target. DLG4 was found to be expressed in normal human cells, including cervical keratinocytes, but only to a limited extent in both HPV-positive and HPV-negative cervical cancer cell lines. Expression of HPV18 E6 in HCK1T decreased DLG4 levels more strongly than did HPV16 E6, the carboxy-terminal motif of the proteins being critical for binding and degradation of DLG4 in vitro. DLG4 levels were restored by expression of either E6AP-specific short hairpin RNA or bovine papillomavirus type 1 E2 in HeLa but not CaSki or SiHa cells, reflecting downregulation of DLG4 mRNA as opposed to protein by an HPV-independent mechanism in HPV16-positive cancer lines. The tumorigenicity of CaSki cells was strongly inhibited by forced expression of DLG4, while growth in culture was not inhibited at all. These results suggest that DLG4 may function as a tumor suppressor in the development of HPV-associated cancers.

Cell Line↗

PubMed2006

Cdt1 revisited: complex and tight regulation during the cell cycle and consequences of deregulation in mammalian cells.

In eukaryotic cells, replication of genomic DNA initiates from multiple replication origins distributed on multiple chromosomes. To ensure that each origin is activated precisely only once during each S phase, a system has evolved which features periodic assembly and disassembly of essential pre-replication complexes (pre-RCs) at replication origins. The pre-RC assembly reaction involves the loading of a presumptive replicative helicase, the MCM2-7 complexes, onto chromatin by the origin recognition complex (ORC) and two essential factors, CDC6 and Cdt1. The eukaryotic cell cycle is driven by the periodic activation and inactivation of cyclin-dependent kinases (Cdks) and assembly of pre-RCs can only occur during the low Cdk activity period from late mitosis through G1 phase, with inappropriate re-assembly suppressed during S, G2, and M phases. It was originally suggested that inhibition of Cdt1 function after S phase in vertebrate cells is due to geminin binding and that Cdt1 hyperfunction resulting from Cdt1-geminin imbalance induces re-replication. However, recent progress has revealed that Cdt1 activity is more strictly regulated by two other mechanisms in addition to geminin: (1) functional and SCFSkp2-mediated proteolytic regulation through phosphorylation by Cdks; and (2) replication-coupled proteolysis mediated by the Cullin4-DDB1Cdt2 ubiquitin ligase and PCNA, an eukaryotic sliding clamp stimulating replicative DNA polymerases. The tight regulation implies that Cdt1 control is especially critical for the regulation of DNA replication in mammalian cells. Indeed, Cdt1 overexpression evokes chromosomal damage even without re-replication. Furthermore, deregulated Cdt1 induces chromosomal instability in normal human cells. Since Cdt1 is overexpressed in cancer cells, this could be a new molecular mechanism leading to carcinogenesis. In this review, recent insights into Cdt1 function and regulation in mammalian cells are discussed.

Journal Article↗

PubMed2006

Intrinsic function of S100A8/A9 complex as an anti-inflammatory protein in liver injury induced by lipopolysaccharide in rats.

BACKGROUND: We hypothesized that the S100A8/A9 complex is effective in the suppression of acute inflammatory changes. METHODS: To clarify such a functional role of the S100A8/A9 complex in acute inflammatory disorder, the complex purified from human leukocytes (approx. 1 mg) was intraperitoneally injected into rats 1.0 or 3.5 h after an injection of lipopolysaccharide (LPS). RESULTS: The serum concentrations of interleukin-6 (IL-6) and nitric oxide (NOx) were significantly decreased in the treated rats. Conversely, when anti-S100A8/A9 complex IgG was injected into the tail blood vessel of a rat 1.0 h after the injection of LPS, the serum concentration of IL-6 increased slightly, indicating that the antibody immunoregulatorily blocked the activity of the complex as an anti-inflammatory protein in vivo. In addition, the S100A8/A9 complex bound non-specifically with interleukin-1beta (IL-1beta), IL-6 and TNF-alpha in vitro, suggesting that the complex could bind with these cytokines in vivo. A large number of endogenous S100A8/A9 complex-positive cells that accumulated in the inflamed region in the liver 6 h after the injection of LPS were microscopically observed, while apparent inflammatory changes were not found microscopically in other organs, such as the kidney, lung and spleen. In rats treated with the S100A8/A9 complex, neither acute inflammatory changes nor S100A8/A9 complex-positive cells were also observed microscopically in the liver tissue. CONCLUSIONS: These findings suggest that the S100A8/A9 complex indirectly suppresses the overproduction of NOx from activated neutrophils and/or macrophages by neutralizing the activity of pro-inflammatory cytokines. Thus, the S100A8/A9 complex may play an important role in the suppression of acute inflammation by modulating the vital activity of pro-inflammatory cytokines in vivo.

Animals↗

PubMed2006

Deregulation of Cdt1 induces chromosomal damage without rereplication and leads to chromosomal instability.

The activity of human Cdt1 is negatively regulated by multiple mechanisms. This suggests that Cdt1 deregulation may have a deleterious effect. Indeed, it has been suggested that overexpression of Cdt1 can induce rereplication in cancer cells and that rereplication activates Ataxia-telangiectasia-mutated (ATM) kinase and/or ATM- and Rad3-related (ATR) kinase-dependent checkpoint pathways. In this report, we highlight a new and interesting aspect of Cdt1 deregulation: data from several different systems all strongly indicate that unregulated Cdt1 overexpression at pathophysiological levels can induce chromosomal damage other than rereplication in non-transformed cells. The most important finding in these studies is that deregulated Cdt1 induces chromosomal damage and activation of the ATM-Chk2 DNA damage checkpoint pathway even in quiescent cells. These Cdt1 activities are negatively regulated by cyclin A/Cdks, probably through modification by phosphorylation. Furthermore, we found that deregulated Cdt1 induces chromosomal instability in normal human cells. Since Cdt1 is overexpressed in cancer cells, this would be a new molecular mechanism leading to carcinogenesis.

Animals↗

PubMed2006

Multislice computed tomography accurately quantifies left atrial size and function after the MAZE procedure.

BACKGROUND: Although the MAZE procedure allows for the recovery of sinus rhythm and left atrial (LA) mechanical function in the great majority of patients with chronic atrial fibrillation (AF), the effects of MAZE on the precise LA geometry and wall motion remain to be elucidated. We hypothesized that LA size and mechanical function in patients with chronic AF and mitral valvular disease are well restored after MAZE. METHODS AND RESULTS: We studied 14 patients (MAZE group: mean+/-SD age, 63.9+/-8.6 years; 8 men and 6 women) who underwent MAZE for chronic AF and mitral valve surgery and 10 patients with sinus rhythm (coronary artery bypass graft [CABG] group: age, 70.0+/-7.9 years; 5 men and 5 women) who underwent CABG at Takeda Hospital between February 2002 and September 2005. MAZE was conducted by the endocardial application of radiofrequency ablation with a temperature-controlled multipolar radiofrequency catheter. LA volume and booster function were quantitatively evaluated by multislice computed tomography at 17.9+/-10.0 months (MAZE group) and 15.3+/-13.6 months (CABG group) postoperatively. All patients with MAZE were free of AF and other atrial arrhythmias during the follow-up period. In the CABG group, LA maximal and minimal volumes and ejection fraction were 109+/-12 mL, 82+/-11 mL, and 26+/-10%, respectively. In the MAZE group, LA maximal volume was 139+/-17 mL (P=0.187 versus CABG), and LA minimal volume was 121+/-16 mL (P=0.082 versus CABG), with an ejection fraction of 15+/-7% (P=0.004 versus CABG). In both groups, all parts of the LA wall contracted toward the geometric center of the LA. The extent of wall motion was significantly worse in the MAZE group compared with the CABG group. In both groups, LA booster function was inversely correlated with LA maximal volume. CONCLUSIONS: MAZE with radiofrequency ablation is safe and effective for the restoration of sinus rhythm in patients with chronic AF and mitral valve disease. However, chronic AF associated with mitral valve disease deteriorates LA mechanical function diffusely throughout the LA wall. Further studies with the use of multislice computed tomography are needed to sequentially evaluate LA function after MAZE in patients with and without mitral valve surgery.

Aged↗

PubMed2006

Two E3 ubiquitin ligases, SCF-Skp2 and DDB1-Cul4, target human Cdt1 for proteolysis.

Replication licensing is carefully regulated to restrict replication to once in a cell cycle. In higher eukaryotes, regulation of the licensing factor Cdt1 by proteolysis and Geminin is essential to prevent re-replication. We show here that the N-terminal 100 amino acids of human Cdt1 are recognized for proteolysis by two distinct E3 ubiquitin ligases during S-G2 phases. Six highly conserved amino acids within the 10 first amino acids of Cdt1 are essential for DDB1-Cul4-mediated proteolysis. This region is also involved in proteolysis following DNA damage. The second E3 is SCF-Skp2, which recognizes the Cy-motif-mediated Cyclin E/A-cyclin-dependent kinase-phosphorylated region. Consistently, in HeLa cells cosilenced of Skp2 and Cul4, Cdt1 remained stable in S-G2 phases. The Cul4-containing E3 is active during ongoing replication, while SCF-Skp2 operates both in S and G2 phases. PCNA binds to Cdt1 through the six conserved N-terminal amino acids. PCNA is essential for Cul4- but not Skp2-directed degradation during DNA replication and following ultraviolet-irradiation. Our data unravel multiple distinct pathways regulating Cdt1 to block re-replication.

Animals↗

PubMed2006

Impact of post-traumatic stress disorder and job-related stress on burnout: a study of fire service workers.

Burnout and stress are common, related problems in service professionals, and post-traumatic stress disorder (PTSD) is a major concern among fire service workers. The purpose of this study was to evaluate the impact of PTSD and job-related stressors on burnout. A total of 243 fire service workers completed questionnaires, including the Impact of Event Scale-Revised (IES-R), Maslach Burnout Inventory (MBI), and Japan Brief Job Stress Questionnaire. Relationships were found between PTSD and burnout, and between job stressors and burnout. Social support reduced the impact on burnout. Stressors that impacted on burnout in fire service personnel were PTSD-related acute stress and general job-related chronic stress. Countermeasures, not only against job stress, but also against PTSD-related stress, are essential to prevent burnout. Social support and the development of human relationships in the work place are crucial in mitigating burnout.

Adult↗

PubMed2006

Effect of autogenic training on cardiac autonomic nervous activity in high-risk fire service workers for posttraumatic stress disorder.

OBJECTIVE: We investigated the effect of autogenic training (AT) on cardiac autonomic nervous activity in fire services workers with the use of the questionnaire of the Japanese-language version of Impact of Event Scale-Revised (IES-R-J) and indexes of heart rate variability. METHODS: We studied 22 male fire services workers who were divided into posttraumatic stress disorder (PTSD)-related stress group (n=10) and control group (n=12). They underwent AT twice or three times a week for 2 months. RESULTS: Posttraumatic stress disorder-related stress group showed a significantly higher cardiac sympathetic nervous activity and a significantly lower cardiac parasympathetic nervous activity than control group at baseline. Autogenic training significantly decreased cardiac sympathetic nervous activity and significantly increased cardiac parasympathetic nervous activity in both groups. These changes were accompanied by a significant decrease in the total points of IES-R-J. CONCLUSION: Autogenic training is effective for ameliorating the disturbance of cardiac autonomic nervous activity and psychological issues secondary to PTSD.

Adult↗

PubMed2006

Sustained-release vancomycin sheet may help to prevent prosthetic graft methicillin-resistant Staphylococcus aureus infection.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of a sustained-release sheet with vancomycin (VCM) to prevent prosthetic graft infection. METHODS: VCM was incorporated into a poly-L-lactide-co-caprolactone (PLCA) sheet (VCM-PLCA). The release profile of VCM from the VCM-PLCA sheet and the tissue concentration of VCM released in vivo were examined. To assess the antibacterial effect of the VCM-PLCA sheet, a sterile Dacron sheet was implanted into 96 male mice (C57BL/6), who were randomly divided into four groups of 24 each and treated as follows: no treatment (group A, control group), a local bolus injection of an aqueous solution of VCM (group B), a plain PLCA sheet (group C), and a VCM-PLCA sheet (group D). After the treatment, methicillin-resistant Staphylococcus aureus (MRSA) (1 x 10(6) colony forming units) was inoculated onto the Dacron graft surface. The Dacron grafts were retrieved on days 3, 7, 10, and 14 after the implantation, and the number of MRSA in the Dacron grafts was counted. RESULTS: VCM was slowly released from the VCM-PLCA sheet over 2 weeks in vivo, and the mean in vivo concentrations of VCM in the tissue around a VCM-PLCA sheet were 7.95, 26.39, 13.87, 12.51, 8.36, and 10.33 mug/mL (the minimum inhibitory concentration of VCM against MRSA is 2.0 mug/ml), at 1, 2, 5, 7, 10, and 14 days after the implantation, respectively. MRSA colonization on the cultivated agar plates was detected in all samples from groups A, B, and C at any postoperative time points. In contrast, some samples were negative for bacterial cultures in group D (2, 3, 1, and 2 samples out of 6 samples each on days 3, 7, 10, and 14 after the implantation, respectively). At all time points, the number of MRSA bacteria in the implanted Dacron graft in group D was by far the lowest (P < .01 at each time point). CONCLUSIONS: The sustained-release sheet with VCM appears to be effective for the reduction of subcutaneous prosthetic graft infection.

Animals↗

PubMed2006

Repeated implantation is a more effective cell delivery method in skeletal myoblast transplantation for rat myocardial infarction.

BACKGROUND: Several clinical trials are underway to determine whether autologous skeletal myoblast transplantation is an effective and safe therapeutic strategy for severe heart failure due to myocardial infarction (MI). It remains unclear whether repeated skeletal myoblast implantation is a feasible and effective cell delivery method for the infarcted myocardium. METHODS AND RESULTS: Four weeks after a coronary ligation, male syngeneic Lewis rats were assigned to 3 treatment groups: 3 episodes of skeletal myoblasts (6x10(6)) transplantation (group I), a bolus transplantation of myoblasts (18x10(6)) (group II), or culture medium injection (group III). Eight weeks after the first treatment, echocardiography, cardiac catheterization and histological examination were performed to compare the therapeutic effects on left ventricular (LV) systolic and diastolic functions, and the engrafted myoblast volume. Repeated myoblast implantation significantly improved LV function and resulted in significantly larger engrafted volume and LV contractility compared with a bolus transplantation with the same number of myoblasts. CONCLUSIONS: Repeated skeletal myoblast transplantation is a safe and effective therapeutic strategy for the infarcted myocardium.

Animals↗

PubMed2006

Combined treatment of sustained-release basic fibroblast growth factor and sarpogrelate enhances collateral blood flow effectively in rabbit hindlimb ischemia.

BACKGROUND: The effectiveness of sustained-release basic fibroblast growth factor (bFGF) in potentiating arteriogenesis and angiogenesis was evaluated, as well as determining whether chronic oral administration of sarpogrelate, a serotonin blocker, would further increase collateral blood flow in the rabbit hindlimb following surgical induction of ischemia by femoral artery extraction. METHODS AND RESULTS: Two weeks after femoral artery removal, the rabbits were assigned to 1 of 4 experimental groups and treated for 4 weeks: group A, no treatment; group B, supplemented with diet containing sarpogrelate; group C, single intramuscular injection of sustained-release form of bFGF microspheres; group D: combined treatment with sustained-release bFGF and sarpogrelate. Endpoint measurements performed at 6 weeks found that the ischemic hindlimb blood flow was significantly improved in the rabbits that received sustained-release bFGF, with a further significant improvement in those with the additional administration of sarpogrelate. Angiographic assessment revealed augmented density of collateral vessels in the medial thigh region in the rabbits given the combined treatment. CONCLUSIONS: The findings demonstrate that sustained-release bFGF stimulated the development of collateral vessels, and additional administration of sarpogrelate produced a further improvement in hindlimb blood flow in the rabbit hindlimb ischemia model.

Animals↗

PubMed2006

[Sex difference in effects of smoking on serum vitamin E concentrations in a young population].

OBJECTIVES: Vitamin E (alpha-tocopherol) is a major endogenous, lipid-soluble antioxidant. Serum concentrations of both alpha-tocopherol and high-density lipoprotein cholesterol (HDL-C) are decreased in smokers as well as in men. Effects of smoking on alpha-tocopherol and HDL-C may differ between men and women in a young population. METHODS: Serum levels of a -tocopherol and HDL-C were compared between smokers and nonsmokers among 126 apparently healthy subjects (< 50 years, mean age of 37 +/- 8 years). RESULTS: Both alpha-tocopherol and HDL-C were significantly lower in men (n = 48) than in women (n = 78) (3.57 +/- 0.47 vs 4.18 +/- 0.65 mg/g lipids; 49.8 +/- 10.6 vs 61.3 +/- 13.4mg/dl). alpha-tocopherol was significantly lower in smokers (n = 29, 3.65 +/- 0.41 mg/g) than in nonsmokers (n = 97, 4.03 +/- 0.69 mg/g), whereas HDL-C was not significantly different between smokers (53.4 +/- 14.4 mg/dl) and nonsmokers (58.0 +/- 13.2 mg/dl). alpha-tocopherol was significantly lower in smokers (n = 10, 3.79 +/- 0.38 mg/g) than in nonsmokers (n = 68, 4.23 +/- 0.66mg/g) in women, but comparable between smokers (n = 19, 3.58 +/- 0.42 mg/g) and nonsmokers (n = 29, 3.56 +/- 0.50mg/g) in men. HDL-C was comparable between smokers and nonsmokers in both men(49.6 +/- 12.3 vs 49.9 +/- 9.6mg/dl) and women (60.7 +/- 15.8 vs 61.4 +/- 13.1 mg/dl). alpha-tocopherol was significantly positively correlated with HDL-C in both smokers (r = 0.67) and nonsmokers (r = 0.60) in men. alpha-tocopherol was significantly positively correlated with HDL-C in nonsmokers (r = 0.42) but not in smokers (r = 0.16) in women. CONCLUSIONS: alpha-tocopherol was lower in smokers than in nonsmokers among younger women but not men. Higher HDL-C was preserved even in smokers among younger women. Positive correlation between alpha-tocopherol and HDL-C was preserved in male smokers but not in female smokers. These results suggest alpha-tocopherol exhaustion was exaggerated by smoking-induced oxidative stress in younger women.

Adult↗

PubMed2005

Circadian variation of cardiac autonomic nervous profile is affected in Japanese ambulance men with a working system of 24-h shifts.

OBJECT: The purpose of this study was to compare the stress levels of Japanese ambulance men between on-duty and off-duty days, by using the physiological indices of heart rate variability (HRV) and cortisol in urine, measured over each 24-h period. METHODS: Measurements were made during one on-duty and one off-duty day for each subject. The participants were monitored for 24 h with a Holter recording system and a parameter reflecting overall stress levels was obtained by measuring the cortisol level in urine collected over 24 h. RESULTS: The circadian variation of cardiac autonomic nervous system activity was affected when the subjects were on duty. The low-frequency/high-frequency power ratio (=low-frequency power/high-frequency power: LF/HF), which is a useful parameter that reflects the balance of cardiac autonomic nervous activity, differed significantly between the waking and sleeping times on the off-duty day (P=0.03), while it did not differ between these two states on the on-duty day (P=0.56). Similarly, the normalized high-frequency power [=high-frequency/(high-frequency+low-frequency) power: HF/(HF+LF)] ratio, which is a useful measure of the activity of the parasympathetic nervous system, differed significantly between these two states on the off-duty day (P=0.04), while there was no significant difference in the ratio between the two states on the on-duty day (P=0.13). CONCLUSION: These results show that the diurnal balance of the cardiac autonomic nervous system is affected on the on-duty day, even though it is possible for ambulance men to sleep regular hours.

Adult↗

PubMed2005

Activation of ataxia telangiectasia-mutated DNA damage checkpoint signal transduction elicited by herpes simplex virus infection.

Eukaryotic cells are equipped with machinery to monitor and repair damaged DNA. Herpes simplex virus (HSV) DNA replication occurs at discrete sites in nuclei, the replication compartment, where viral replication proteins cluster and synthesize a large amount of viral DNA. In the present study, HSV infection was found to elicit a cellular DNA damage response, with activation of the ataxia-telangiectasia-mutated (ATM) signal transduction pathway, as observed by autophosphorylation of ATM and phosphorylation of multiple downstream targets including Nbs1, Chk2, and p53, while infection with a UV-inactivated virus or with a replication-defective virus did not. Activated ATM and the DNA damage sensor MRN complex composed of Mre11, Rad50, and Nbs1 were recruited and retained at sites of viral DNA replication, probably recognizing newly synthesized viral DNAs as abnormal DNA structures. These events were not observed in ATM-deficient cells, indicating ATM dependence. In Nbs1-deficient cells, HSV infection induced an ATM DNA damage response that was delayed, suggesting a functional MRN complex requirement for efficient ATM activation. However, ATM silencing had no effect on viral replication in 293T cells. Our data open up an interesting question of how the virus is able to complete its replication, although host cells activate ATM checkpoint signaling in response to the HSV infection.

Acid Anhydride Hydrolases↗

PubMed2005

Recent insights into the mechanisms, predisposing factors, and racial differences of coronary vasospasm.

Coronary vasospasm is currently considered to be an exaggerated contractile nonspecific response of the vascular smooth muscle in the large coronary artery to various agonists or stimulation, that is established after the process of inflammation and fibrocellular proliferation. Endothelial dysfunction with reduced nitric oxide bioavailability has been reported in angiographically normal coronary arteries in Japanese patients with coronary spastic angina. Recently, several interesting findings concerning the exact mechanism of calcium hypersensitivity of spastic vascular smooth muscle have been reported. In animal models with coronary spasm Rho-kinase is upregulated at the spastic site and plays a key role in inducing vascular smooth muscle hypercontraction by inhibiting myosin light chain phosphatase, resulting in enhancement of its phosphorylation. Also, oxidative stress has been given attention as an important mediator of the spastic conversion of vascular smooth muscle cell "phenotype." The incidence of coronary spastic angina in the Japanese population is reported to be remarkably high compared with that in Caucasians. Clinical and pathophysiological differences between Japanese and Caucasian patients with respect to coronary vasospasm are characterized by a lower prevalence of fixed coronary artery stenoses and diffuse coronary hyperreactivity in the Japanese patients. Recently, several distinct characteristics have been recognized to be associated with coronary vasospasm in studies analyzing data obtained from Japanese patients. In the present review, we will discuss our point of view on the mechanisms and predisposing factors in coronary vasospasm. Predisposing factors include smoking, lipid metabolic disorders, and gene expression, all of which may be interrelated issues.

Asian People↗

PubMed2005

Architecture of replication compartments formed during Epstein-Barr virus lytic replication.

Epstein-Barr virus (EBV) productive DNA replication occurs at discrete sites, called replication compartments, in nuclei. In this study we performed comprehensive analyses of the architecture of the replication compartments. The BZLF1 oriLyt binding proteins showed a fine, diffuse pattern of distribution throughout the nuclei at immediate-early stages of induction and then became associated with the replicating EBV genome in the replication compartments during lytic infection. The BMRF1 polymerase (Pol) processivity factor showed a homogenous, not dot-like, distribution in the replication compartments, which completely coincided with the newly synthesized viral DNA. Inhibition of viral DNA replication with phosphonoacetic acid, a viral DNA Pol inhibitor, eliminated the DNA-bound form of the BMRF1 protein, although the protein was sufficiently expressed in the cells. These observations together with the findings that almost all abundantly expressed BMRF1 proteins existed in the DNA-bound form suggest that the BMRF1 proteins not only act at viral replication forks as Pol processive factors but also widely distribute on newly replicated EBV genomic DNA. In contrast, the BALF5 Pol catalytic protein, the BALF2 single-stranded-DNA binding protein, and the BBLF2/3 protein, a component of the helicase-primase complex, were colocalized as distinct dots distributed within replication compartments, representing viral replication factories. Whereas cellular replication factories are constructed based on nonchromatin nuclear structures and nuclear matrix, viral replication factories were easily solubilized by DNase I treatment. Thus, compared with cellular DNA replication, EBV lytic DNA replication factories would be simpler so that construction of the replication domain would be more relaxed.

Antigens, Viral↗

PubMed2005

Cough reflex by ventricular premature contractions.

A 72-year-old man was referred for further assessment of a chronic cough. He noticed an association between the episodes of coughing and palpitations. Electrocardiography (ECG) revealed normal sinus rhythm and sporadic unifocal ventricular premature contractions (VPCs). Each cough was preceded by a premature beat. Continuous wave Doppler echocardiography revealed a VPC-induced transient increase in the pulmonary artery blood flow. He was successfully treated for VPCs with oral disopyramide, resulting in subsidence of both the coughing and palpitations. We suspect that the VPC-induced hemodynamic changes in the pulmonary circulation might be responsible for coughing in our patient. Premature contractions should be considered as a possible cause of chronic dry cough in the clinical setting.

Anti-Arrhythmia Agents↗