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Atsuhiko Hasegawa

Publications and source records attributed to Atsuhiko Hasegawa.

At least 19 recordsLinked to original sources
PubMed2007

Microreview: capsule-associated genes of Cryptococcus neoformans.

Cryptococcosis, caused by Cryptococcus neoformans is a common systemic mycosis in man and animals, particularly immunocompromised patients. This pathogenic fungus produces a thick extracellular polysaccharide capsule. Four capsule-associated genes (CAP10, CAP59, CAP60, CAP64) were cloned and sequenced, and proved to be essential for capsule synthesis. However biochemical functions of CAP gene products have not been clarified yet. Recently, the relatedness of the polysaccharide capsule and four capsule-associated genes has partly been elucidated. Nucleotide sequence of four CAP gene fragments was analyzed for phylogenetic relationships, and they were in agreement with the conventional classification of varieties and serotypes within C. neoformans. Expression of four CAP genes and capsule size were examined using two media containing different amount of glucose, and the results indicated that CAP genes might play important roles in elaboration of extracellular polysaccharide capsule. Furthermore, analyses of CAP genes in various clinical samples would give the useful information to diagnose cryptococcosis in human and animals.

Animals↗
PubMed2006

An isolate of Prototheca wickerhamii from systemic canine protothecosis.

The isolate from a canine disseminated protothecosis was identified to be Prototheca wickerhamii by its morphological and biochemical characteristics. The isolate was grouped into a cluster identical to the type strain of P. wickerhamii, ATCC 16529(T) in phylogenetic trees based on the small subunit (SSU) and the 5' end of the large subunit (LSU) ribosomal DNA (rDNA); the cluster was close to that including the other Prototheca species. However, the strains of P. wickerhamii, SAG 263-11 and Pore 1283 belonged to a cluster different from the other isolates of Prototheca species and closely related to those of Auxenochorella species. Therefore, P. wickerhamii could be divided into two distinct genetic groups, one group close to the other Prototheca spp. including a standard strain of P. wickerhamii, and another group consisting of isolates previously reported to be close to the Auxenochorella species.

Animals↗
PubMed2006

Capsule-associated genes of serotypes of Cryptococcus neoformans, especially serotype AD.

Cryptococcus neoformans has been divided into five serotypes (A, B, C, D and AD) by the slide agglutination test against antigens of the polysaccharide capsule component. The isolates of serotype AD show positive reactions with both serotype A and D antigens. In this study, the nucleotide sequences of the capsule-associated genes CAP10, CAP59, CAP60 and CAP64 from five serotypes of C. neoformans were analyzed for their phylogenetic relationships, with special regard to serotype AD. The nucleotide sequence analyses showed that serotype AD had two different sequences in these four genes. Phylogenetic analysis revealed that these genes from serotype AD are included in the two clusters of serotypes A and D, but not in serotypes B or C. Southern blot analysis of genomic DNAs of serotypes A, D and AD digested with BamH I by hybridizing with a CAP64 probe indicated that both bands of fragments detected in serotypes A and D were also detected in serotype AD. These results confirm that serotype AD could be a mixture of serotypes A and D in the four CAP genes, consistent with its putative origin detected by the hybridization of these two serotypes. The present results indicated that serotypes of C. neoformans could be identified by the phylogenetic analyses of CAP genes.

Bacterial Capsules↗
PubMed2006

Recombinant vaccinia DIs expressing simian immunodeficiency virus gag and pol in mammalian cells induces efficient cellular immunity as a safe immunodeficiency virus vaccine candidate.

A highly attenuated vaccinia virus substrain of Dairen-I (DIs) shows promise as a candidate vector for eliciting positive immunity against immune deficiency virus. DIs was randomly obtained by serial 1-day egg passages of a chorioarantoic membrane-adapted Dairen strain (DIE), resulting in substantial genomic deletion, including various genes regulating the virus-host-range. To investigate the impact of that deletion and of the subsequent insertion of a foreign gene into that region of DIs on the ability of the DIs recombinant to induce antigen-specific immunity, we generated a recombinant vaccinia DIs expressing fulllength gag and pol genes of simian immunodeficiency virus (SIV) (rDIsSIV gag/pol) and studied the biological and immunological characteristics of the recombinant natural mutant. The rDIsSIV gag/pol developed a tiny plaque on the chick embryo fibroblast (CEF). Viral particles of rDIsSIV gag/pol as well as SIV Gag-like particles were electromicroscopically detected in the cytoplasm. Interestingly, the recombinant DIs strain grows well in CEF cells but not in mammalian cells. While rDIsSIV gag/pol produces SIV proteins in mammalian HeLa and CV-1 cells, recombinant modified vaccinia Ankara strain (MVA) expressing SIV gag and pol genes (MVA/SIV239 gag/pol) clearly replicates in HeLa and CV-1 cell lines under synchronized growth conditions and produces the SIV protein in all cell lines. Moreover, intradermal administration of rDIsSIV gag/pol or of MVA/SIV239 gag/pol elicited similar levels of IFN-gamma spot-forming cells specific for SIV Gag. If the non-productive infection characteristically induced by recombinant DIs is sufficient to trigger immune induction, as we believe it is, then a human immunodeficiency virus vaccine employing the DIs recombinant would have the twin advantages of being both effective and safe.

Animals↗
PubMed2006

A randomized comparative clinical trial of recombinant canine interferon-gamma (KT-100) in atopic dogs using antihistamine as control.

Recombinant canine interferon-gamma (KT-100) or topical antihistamine (diphenhydramine: DH) was administered to dogs with atopic dermatitis (AD) for 4 weeks and their efficacies were compared using pruritus, excoriation, erythema and alopecia as evaluation criteria. Clinical studies on 92 atopic dogs (KT-100 group: 63, DH group: 29) were conducted at 18 animal hospitals in Japan. KT-100 was administered subcutaneously once a day three times a week on alternating days for 4 weeks. DH was administered topically twice daily for 4 weeks. The efficacy rates of the KT-100 group on day 28 were 72.1% for pruritus, 73.8% for excoriation, 75.4% for erythema and 60.7% for alopecia, which were significantly higher than those of the DH group (20.7% for pruritus, 27.6% for excoriation, 24.1% for erythema and 24.1% for alopecia).

Administration, Topical↗
PubMed2006

Reduction of human T-cell leukemia virus type 1 (HTLV-1) proviral loads in rats orally infected with HTLV-1 by reimmunization with HTLV-1-infected cells.

Human T-cell leukemia virus type 1 (HTLV-1) persistently infects humans, and the proviral loads that persist in vivo vary widely among individuals. Elevation in the proviral load is associated with serious HTLV-1-mediated diseases, such as adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. However, it remains controversial whether HTLV-1-specific T-cell immunity can control HTLV-1 in vivo. We previously reported that orally HTLV-1-infected rats showed insufficient HTLV-1-specific T-cell immunity that coincided with elevated levels of the HTLV-1 proviral load. In the present study, we found that individual HTLV-1 proviral loads established in low-responding hosts could be reduced by the restoration of HTLV-1-specific T-cell responses. Despite the T-cell unresponsiveness for HTLV-1 in orally infected rats, an allogeneic mixed lymphocyte reaction in the splenocytes and a contact hypersensitivity response in the skin of these rats were comparable with those of naive rats. HTLV-1-specific T-cell response in orally HTLV-1-infected rats could be restored by subcutaneous reimmunization with mitomycin C (MMC)-treated syngeneic HTLV-1-transformed cells. The reimmunized rats exhibited lower proviral loads than untreated orally infected rats. We also confirmed that the proviral loads in orally infected rats decreased after reimmunization in the same hosts. Similar T-cell immune conversion could be reproduced in orally HTLV-1-infected rats by subcutaneous inoculation with MMC-treated primary T cells from syngeneic orally HTLV-1-infected rats. The present results indicate that, although HTLV-1-specific T-cell unresponsiveness is an underlying risk factor for the propagation of HTLV-1-infected cells in vivo, the risk may potentially be reduced by reimmunization, for which autologous HTLV-1-infected cells are a candidate immunogen.

Administration, Oral↗
PubMed2006

Apoptosis of canine mammary tumor cells induced by small interfering RNA (siRNA) against Bcl-xL gene.

The inhibition of Bcl-xL mRNA expression and the acceleration of apoptotic cell rates in canine mammary tumor cell line (CF33) by the small interfering RNA (siRNA) were analyzed. The level of Bcl-xL transcripts in CF33 was decreased when cultured with siRNA, suggesting that siRNA might inhibit the expression of Bcl-xL mRNA in the CF33. Apoptotic cell rates in CF33 cultured with siRNA in Oligofectamine medium, with double strand RNA in Oligofectamine medium, without siRNA in Oligofectamine medium and in DMEM alone were 60.9%, 30%, 28.7% and 11.6% at 48-hr incubation, respectively, when evaluated by TUNEL assay. From these results, it was suggested that canine Bcl-xL might be an anticancer target of canine tumors.

Animals↗
PubMed2006

Phenotypic analysis of hepatic T lymphocytes in a dog with chronic hepatitis.

We evaluated hepatic T lymphocyte phenotypes in a dog with chronic hepatitis. Before treatment, numerous CD3+ lymphocytes were demonstrated in the liver, and the ratio of CD4+/CD8+ was remarkably high (2.96; reference range, 0.33+/-0.12). After treatment, CD3+ lymphocyte infiltration in the liver was reduced, and the ratio of CD4+/CD8+ decreased to 0.31. Therefore, hepatic T lymphocytes, especially CD4+ lymphocytes, might play a central role in the pathogenesis of this dog with chronic hepatitis.

Adrenal Cortex Hormones↗
PubMed2006

Evaluation of right ventricular Tei index (index of myocardial performance) in healthy dogs and dogs with tricuspid regurgitation.

Right ventricular (RV) Tei index (index of myocardial performance) has been demonstrated to be clinically useful in estimating RV function in various human cardiac diseases. The purposes of this study were to validate the correlation between RV Tei index and RV function obtained by cardiac catheterization in healthy dogs, and to evaluate the RV Tei index in dogs with tricuspid regurgitation (TR). In healthy dogs, the RV Tei index significantly correlated with the RV peak +dP/dt (r=-0.80, p<0.0001) and -dP/dt (r=0.69, p=0.0001). In normal dogs, the RV Tei index was not significantly correlated with heart rate, body weight, and age. The RV Tei index significantly increased in dogs with moderate to severe TR (0.39 +/- 0.35, p=0.0015), filariasis (0.46 +/- 0.16, p=0.0131), and trivial to mild TR and severe mitral regurgitation (MR; 0.61 +/- 0.14, p=0.0017) when compared with the normal dogs (0.17 +/- 0.10). In addition, the RV Tei index in dogs with TR significantly increased in association with pulmonary hypertension [PH(-), 0.19 +/- 0.09; PH(+), 0.65 +/- 0.14; respectively p<0.0001]. Our study has demonstrated that RV Tei index is a feasible approach to estimate RV function in dogs and is not influenced by heart rate, body weight, and aging. Further investigations are required to clarify the clinical significance of RV Tei index in dogs with right-sided cardiac diseases.

Aging↗
PubMed2006

A case of feline pancreatitis.

A 14-year-old, spayed female, domestic shorthair cat was referred to us with anorexia, pyrexia, and jaundice. Total bilirubin (TBIL) and feline trypsin-like immunoreactivity (fTLI) levels were remarkably high. Based on laparoscopic biopsy of the pancreas, the cat was diagnosed as having pancreatitis. As a result of treatment with a synthetic protease inhibitor and corticosteroid, the TBIL and fTLI values returned to normal and the clinical course was good.

Animals↗
PubMed2006

Contrast harmonic imaging of canine hepatic tumors.

Six adult healthy Beagles were used to investigate the hepatic perfusion dynamics of Levovist, a contrast agent used in contrast harmonic imaging (CHI). In addition, 8 dogs with hepatocellular carcinoma (HCC) and 2 dogs with metastatic hepatic hemangiosarcoma (HSA) were used to characterize both the CHI findings with Levovist. In the Beagles, the start of intravenously injected Levovist into the aorta between the cranial mesenteric and renal arteries and the portal vein at the hepatic hilum were 5.47 +/- 1.52 sec and 16.03 +/- 3.39 sec, respectively. As a characteristic CHI finding in the 8 dogs with HCC, the early arterial phase showed a fine network of blood flow enhanced at the surrounding region and within the tumor in all the 8 dogs (100%), and the post vascular phase demonstrated a defect in the whole tumor and an enhancement of the surrounding hepatic tissues in 7 dogs (87.5%). In the 2 dogs with HSA, characteristic finding in which the early arterial and late vascular phases showed a rim contrast enhancement pattern, and the post vascular phase revealed that the whole tumor lacked contrast enhancement and the surrounding hepatic tissues was clearly enhanced. In dogs, the start of the early arterial and late vascular phases, and the characterizations of the CHI findings in HCC and HSA were suggested to be similar to those in humans. Therefore, CHI is thought to be useful for the diagnosis of HCC and metastatic hepatic HSA in dogs as well as in humans.

Animals↗
PubMed2006

Diabetes mellitus after resection of hepatocellular carcinoma with hypoglycemia in a dog.

A 10-year-old male beagle was referred to us with seizure related to hypoglycemia and a large intraabdominal mass. Based on various types of imaging and a laparoscopic biopsy, the intraabdominal mass was diagnosed as a hepatocellular carcinoma (HCC) of the quadrate lobe. The hypoglycemia was suspected to be associated with the HCC. After lobectomy of the quadrate lobe was performed, blood glucose levels continued to increase to higher than normal values and sugar was detected in the urine. The dog was diagnosed as diabetes mellitus (DM) and was treated with insulin for over two years after the surgery.

Animals↗
PubMed2006

Serotypes and mating types of clinical isolates from feline cryptococcosis in Japan.

Most isolates of Cryptococcus neoformans (teleomorph: Filobasidiella neoformans) from human patients and from environmental materials in Japan have been identified as serotype A mating type a by the seroagglutination test and mating experiments. A PCR method using the mating type alpha allele-specific primer of the STE12 gene and the serotype- and mating type-specific primers of the STE20 gene for identification of C. neoformans has been developed. Using the PCR method, conserved strains and clinical isolates from feline cryptococcosis were examined for serotype and the mating type. The results showed that all clinical isolates examined were identified as serotype A, MATalpha, indicating that feline cryptococcsis cases in Japan are caused by C. neoformans serotype A, MATalpha, as is the case in humans.

Animals↗
PubMed2005

Molecular cloning and tissue expression of canine Toll-like receptor 2 (TLR2).

Toll-like receptor 2 (TLR2) is involved in an important role on inflammatory reactions against various pathogenic microorganisms. Although some investigations suggested a relation between human and murine TLR2 gene polymorphisms and infections or inflammatory reactions, canine TLR2 gene has not been investigated. In the present study, therefore, the canine full-length of cDNA of Toll-like receptor 2 gene was sequenced and the expression of canine TLR2 mRNA was investigated in various tissues. Canine TLR2 clone was 2552bp encoding 785 amino acids. The similarities of canine TLR2 with human, mouse, rat, cattle, horse and pig TLR2 were 87.6, 72.9, 73.2, 83.1, 85.1 and 80.7% at the nucleotide sequence level, and 84.6, 68.7, 68.5, 78.8, 82.9 and 79.0% at amino acid sequence level, respectively. By a semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis, mRNA of canine TLR2 was detected in blood mononuclear cells (BMCs), lymph node, lung, liver, spleen, bladder, pancreas, small intestine, large intestine and skin of the dogs.

Amino Acid Sequence↗
PubMed2005

Canine CD20 gene.

The human CD20 antigen, a 35kDa cell surface nonglycosylated hydrophobic phoshpoprotein is expressed consistently on almost all human B-cells, and its monoclonal antibody is used for the therapy on human B-cell lymphoma. In the present study, canine CD20 gene was cloned and sequenced, and the expression of CD20 mRNA was investigated in canine peripheral blood mononuclear cells (PBMCs), and lymph nodes from healthy dogs, and canine lymphoma cells. Using canine cDNA as a template, full-length of canine CD20 gene was sequenced by 5'-RACE and 3'-RACE methods. The full-length of the cDNA sequence of canine CD20 was 1239bp encoding 297 amino acids. The amino acid sequences of canine CD20 showed 73 and 68% sequence similarities with those of human and mouse, respectively. Canine CD20 was predicted to contain domains of amino acid sequences consisting of two extracellular domains (EM), four transmembrane domains (TM), and three intracellular domains (IC) as in human CD20. Canine CD20 mRNA was detected in PBMCs and lymph node from healthy dogs, and B-cells of canine lymphoma, but not in T-cell lymphoma cells and non-T and non-B-cell lymphoma cells by RT-PCR analysis. From these results, canine CD20 might be targeted for monoclonal antibody therapy against B-cell lymphoma of dogs.

Amino Acid Sequence↗
PubMed2005

In vitro effect of recombinant human tumor necrosis factor-alpha on canine neutrophil apoptosis.

Neutrophils (polymorphonuclear leukocytes: PMNs) are essential for the host defense against various infections and are often injurious to the host, causing inflammatory diseases where tumor necrosis factor-alpha (TNF-alpha) is suggested to play an important role. Since an effect of TNF-alpha on canine PMN apoptosis has not been studied, canine PMNs were stimulated with recombinant human (rh)TNF-alpha in the present study to investigate the effect of TNF-alpha on canine PMN apoptosis. PMN apoptosis and function to produce ROS were assessed by flow cytometry. Delayed apoptosis was observed in the PMNs treated with rhTNF-alpha at 100 ng/ml, accompanied by retention of capability to produce ROS. However, PMN apoptosis was accelerated by rhTNF-alpha combined with cycloheximide. Therefore, it is indicated that TNF-alpha is able to activate anti- and pro-apoptotic pathways in PMNs and that the inhibition of PMN apoptosis by TNF-alpha requires protein synthesis in the PMNs.

Animals↗
PubMed2005

In vitro effect of recombinant human granulocyte colony-stimulating factor on canine neutrophil apoptosis.

Apoptosis is essential in eliminating neutrophils (polymorphonuclear leukocytes: PMNs) in animals. The suppression of PMN apoptosis is believed to be beneficial in eradicating pathogens and is implicated in the pathogenesis of human inflammatory diseases. In the present study, canine PMNs were stimulated with recombinant human granulocyte colony-stimulating factor (rhG-CSF) to investigate the in vitro effect on the apoptosis of canine PMNs. Apoptotic cell rates were assessed by flow cytometry in relation to the ability of PMNs to produce reactive oxygen species (ROS). Canine PMN apoptosis was markedly suppressed by rhG-CSF treatment, in association with the retention of the PMN ability to produce ROS. The addition of cycloheximide abolished this suppression by rhG-CSF. Moreover, canine PMNs, which were stimulated by rhG-CSF, expressed high levels of anti-apoptotic mcl-1 gene mRNA, as quantified by real-time polymerase chain reaction method. The results suggest that PMNs, stimulated by G-CSF, could work effectively over a longer period to eliminate pathogens, and that the prolongation of the PMN life-span might occasionally aggravate tissue injuries in dogs. In addition, the suppression of PMN apoptosis seems to be mediated by the induction of anti-apoptotic mcl-1 gene expression.

Animals↗