Biomedical subjects
Publications and source records attributed to Tetsuo Hashimoto.
Babesia microti-like parasites were detected for the first time in Ixodes ovatus in Hyogo Prefecture, Japan, where two reported types of B. microti-like parasites were recognized in many rodents. Of 80 adult I. ovatus ticks collected, 5 possessed the reported type and 1 possessed a new type of B. microti-like parasite.
Recently, the contribution of the immune system in the development and progression of arteriosclerosis has been suggested. Moreover, psychological stress has also been reported to affect the immune response. Thus, psychological factors are considered to influence the immune response, and an excessive immune response promotes the progression of arteriosclerosis, resulting in the development of coronary heart disease (CHD). In this study, the relationship between the immune response and psychological factors was investigated in CHD patients (n = 74) and normal controls (n = 64). Natural killer (NK) activity was significantly higher in the CHD group than the normal control (CHD vs normal: 8151.39 vs 6653.06, P < 0.05), and was significantly elevated by the suppression of anger and negative emotions (P < 0.05). These results indicate that the characteristic process of psychological response in CHD patients is related to an overresponse of NK activity. We speculate that this linkage significantly influences the development of CHD.
Although an autoimmune mechanism has been postulated for myocarditis and dilated cardiomyopathy, immunosuppressive agents had not been shown to be effective. Potential benefits of intravenous immunoglobulin (IVIg) in the therapy of patients with myocarditis and recent onset of dilated cardiomyopathy were reported. Also, experimental studies showed that IVIg is an effective therapy for viral myocarditis by antiviral and anti-inflammatory effects. Accordingly, in the current study, the effects of IVIg in the patients were investigated with the analyses of inflammatory cytokines and oxidative stress. Nine patients (six in myocarditis, three in acute dilated cardiomyopathy) were treated with high-dose intravenous IVIg (1-2 g/kg, over 2 days). All were hospitalized with New York Heart Association (NYHA) class III to IV heart failure, left ventricular ejection fraction (LVEF) <40%, and symptoms for <6 months at the time of presentation. Five patients were diagnosed using endomyocardial biopsy. LVEF determined by echocardiography improved from 19.0+/-7.5% (mean+/-S.D.) at baseline to 35.4+/-9.1% at follow up (12.2+/-5.8 days after the treatment) (P<0.01). C-reactive protein and plasma inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6) were decreased by this treatment. In addition, plasma level of thioredoxin, which regulates the cellular state of oxidative stress, was decreased by the treatment. All nine patients improved functionally to NYHA class I to II, and were discharged without side-effects. There have been no subsequent hospitalizations for heart failure during the course of follow-up (3 months-4.5 years). LVEF improved 16% of EF in the patients with myocarditis and acute dilated cardiomyopathy with the reduction of cytokines associated with improvement of oxidative stress state by high-dose of IVIg. Thus, IVIg seems to be a promising agent in the therapy of acute inflammatory cardiomyopathy in view of not only suppression of inflammatory cytokines but a reduction of oxidative stress.
An important role of redox regulation in myocardial diseases and heart failure has been postulated. Thioredoxin (TRX) is a redox-regulating protein. Recent studies indicated a possible association between plasma TRX concentrations and the severity of heart failure. Accordingly, we investigated the myocardial expression of TRX in patients with myocarditis and cardiomyopathies. Four cases of hypertrophic cardiomyopathy (HCM), 10 of dilated cardiomyopathy (DCM), 6 of myocarditis, and 5 of controls were studied. Right and left ventricular endomyocardial biopsy samples were obtained at the diagnostic cardiac catheterization. The samples were processed for immunohistological staining for TRX, which was done by the indirect immunoperoxidase technique. 8-hydoxy-2'-deoxyguanosine (8-OHdG), one of the major DNA base-modified products, was also detected for an established marker for oxidative stress. TRX immunoreactivity was none or trivial in control specimens. Positive TRX staining was found in 6 cases; 3 in active myocarditis and 3 in DCM. The positive staining was found in infiltrating cells and damaged myocytes in the perinecrotic lesions. Damaged myocytes were also positive for 8-OHdG All the 3 cases of DCM positive for TRX stain showed severe left ventricular hypertrophy on electrocardiogram and highly elevated left ventricular end-diastolic pressure (> 24 mmHg), suggesting the overload of oxidative stress by hemodynamic impairment. Myocardial TRX was upregulated in myocarditis and cardiomyopathies with active necrotic stage associated with DNA damage, which may reflect the oxidative stress overload in hemodynamically uncontrolled status.
Genes encoding putative mitochondrial-type heat shock protein 70 (mit-hsp70) were isolated and sequenced from amitochondriate protists, Giardia intestinalis, Entamoeba histolytica, and two microsporidians, Encephalitozoon hellem and Glugea plecoglossi. The deduced mit-hsp70 sequences were analyzed by sequence alignments and phylogenetic reconstructions. The mit-hsp70 sequence of these four amitochondriate protists were divergent from other mit-hsp70 sequences of mitochondriate eukaryotes. However, all of these sequences were clearly located within a eukaryotic mitochondrial clade in the tree including various type hsp70 sequences, supporting the emerging notion that none of these amitochondriate lineages are primitively amitochodrial, but lost their mitochondria secondarily in their evolutionary past.
To determine whether c-Fos and c-Jun are involved in the repair of small intestinal mucosa after ischemia-reperfusion (I/R), we investigated the mechanism of regeneration following acute I/R injury in rats by evaluating changes in DNA synthesis, fractional synthesis rate (FSR) of proteins, and alkaline phosphatase (ALP) activity. Furthermore, we examined the sequential expression of c-Fos and c-Jun using western blot analysis and immunohistochemical staining. Proliferating cell nuclear antigen (PCNA) labeling index (LI) demonstrated that the LI of the I/R group at 2 and 6 hr after reperfusion was significantly higher than that of the controls. Statistically significant differences were found between the FSRs of the I/R group and the corresponding conventional group at 2, 6, and 12 hr. The expression of c-Fos and c-Jun proteins increased markedly after I/R and these proteins decreased with time. The levels of ALP in the I/R group were significantly decreased at 2 and 6 hr after reperfusion compared to controls. These results indicate that c-Fos and c-Jun play a central role in the repair process that results in complete restoration of intestinal mucosal function after I/R.
A 31-year-old woman suspected to have acute myocarditis was admitted to hospital and was managed with intra-aortic balloon pumping and a percutaneous cardiopulmonary support system because of sustained ventricular tachycardia. After immunoglobulin treatment, cardiac function and systematic inflammation were improved. The left ventricular endomyocardial biopsy revealed massive necrosis and degeneration of myocardial cells, and extensive infiltration of inflammatory cells. The clinicopathology of this patient was thought to be fulminant myocarditis. Serial serum thioredoxin (TRX) analysis showed that the serum level was high during the acute phase, and decreased during the chronic phase. Immunohistochemistry for TRX in the biopsy samples showed that inflammatory cells and cardiomyocytes were positively stained.
Blastocystis hominis, a parasite of the human intestine, has recently been positioned within stramenopiles by the small subunit rRNA phylogeny. To further confirm its phylogenetic position using multiple molecular sequence data, we determined the nucleotide sequences putatively encoding small subunit ribosomal RNA, cytosolic-type 70-kDa heat shock protein, translation elongation factor 2, and the non-catalytic 'B' subunit of vacuolar ATPase of B. hominis (HE87-1 strain). Moreover, we determined the translation elongation factor 2 sequence of an apicomplexan parasite, Plasmodium falciparum, that belongs to alveolates. The maximum likelihood analyses of small subunit rRNA and cytosolic-type 70-kDa heat shock protein clearly demonstrated that B. hominis (HE87-1 strain) is positioned within stramenopiles, being congruent with the previous small subunit rRNA analysis, including the sequences of B. hominis (Nand strain) and a Blastocystis isolate from guinea pig. Although no clear resolution among major eukaryotic groups was obtained by the individual phylogenies based on the four molecules analyzed here, a combined analysis of various molecules, including these, clearly indicated that Blastocystis/stramenopiles are the closest relatives of alveolates.
To clarify evolution and phylogenetic relationships of trypanosome alternative oxidase (AOX) molecules, AOX genes (cDNAs) of the African trypanosomes, Trypanosoma congolense and Trypanosoma evansi, were cloned by PCR. Both AOXs possess conserved consensus motifs (-E-, -EXXH-). The putative amino acid sequence of the AOX of T. evansi was exactly the same as that of T. brucei. A protein phylogeny of trypanosome AOXs revealed that three genetically and pathogenically distinct strains of T. congolense are closely related to each other. When all known AOX sequences collected from current databases were analyzed, the common ancestor of these three Trypanosoma species shared a sister-group position to T. brucei/T. evansi. Monophyly of Trypanosoma spp. was clearly supported (100% bootstrap value) with Trypanosoma vivax placed at the most basal position of the Trypanosoma clade. Monophyly of other eukaryotic lineages, terrestrial plants + red algae, Metazoa, diatoms, Alveolata, oomycetes, green algae, and Fungi, was reconstructed in the best AOX tree obtained from maximum likelihood analysis, although some of these clades were not strongly supported. The terrestrial plants + red algae clade showed the closest affinity with an alpha-proteobacterium, Novosphingobium aromaticivorans, and the common ancestor of these lineages, was separated from other eukaryotes. Although the root of the AOX subtree was not clearly determined, subsequent phylogenetic analysis of the composite tree for AOX and plastid terminal oxidase (PTOX) demonstrated that PTOX and related cyanobacterial sequences are of a monophyletic origin and their common ancestor is linked to AOX sequences.