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Biomedical subjects

R Yamaguchi

Publications and source records attributed to R Yamaguchi.

At least 19 recordsLinked to original sources
PubMed1999

Encephalopathy in suckling mice infected with Kasba (Chuzan) virus.

Kasba (Chuzan) virus (an orbivirus), strain K-47, produced encephalopathy with severe necrosis in suckling mice inoculated intracerebrally. On day 3 after inoculation with 10(3)TCID50, the mice showed severe focal encephalomalacia and meningitis. On day 4, necrosis had spread to the midbrain, cerebellum and spinal cord. From one day after inoculation, virus was recovered from the brain and the titre rose over the next 3 days. Immunohistochemical examination demonstrated viral antigens in the cytoplasm of both degenerate and intact neurons, and ependymal cells in or around necrotic lesions. The study indicated that the virus has an affinity for immature nerve cells in the brains of suckling mice and causes primary encephalomalacia. Since the lesions resembled those of the hydranencephaly-cerebellar hypoplasia syndrome in calves (Chuzan disease), the system described should prove useful in studies on pathogenesis.

Animals↗
PubMed1999

Non-purulent meningoencephalomyelitis of a Pacific striped dolphin (Lagenorhynchus obliquidens). The first evidence of morbillivirus infection in a dolphin at the Pacific Ocean around Japan.

On March 22, 1998, a mature, male, hyposthenic Pacific striped dolphin (Lagenorhynchus obliquidens) was stranded at Aoshima Beach in Miyazaki prefecture, Japan. A necropsy performed 14 hr after death revealed mild diffuse congestion and edema of the leptomeninges and mild pulmonary atelectasis. Histopathologically, non-purulent inflammatory were observed throughout the cerebrum, thalamus, midbrain, pons, medulla oblongata, and spinal cord. Hematoxylin and eosin stain revealed no viral inclusion bodies. Immunohistochemistry using a monoclonal antibody against nucleoprotein of canine distemper virus (CDV-NP) revealed a number of CDV-NP-positive granular deposits in the cytoplasm and cell processes of the degenerating or intact neurons. The present paper is a first report of spontaneously occurred morbillivirus infection in a dolphin at the Pacific Ocean around Japan.

Animals↗
PubMed1999

Amplification of the c-yes oncogene in canine mammary tumors.

Genomic DNAs of 14 mammary tumors were analyzed by Southern blot hybridization using a human c-yes-1 oncogene probe. The amplification was successful in half of the cases (7 adenocarcinomas). The degree of amplification was approximately 4-fold, and a high proportion was seen in malignant tumors. In addition, DNA polymorphism was detected in two adenocarcinomas.

Adenocarcinoma↗
PubMed1999

Immunohistochemical analysis of c-yes and c-erbB-2 oncogene products and p53 tumor suppressor protein in canine mammary tumors.

In order to evaluate the involvement of c-yes and c-erbB-2 oncogene products, and p53 tumor suppressor protein in canine mammary neoplastic lesions, sections of archived paraffin-embedded samples of 79 mammary tumors were analyzed immunohistochemically using antibodies against human c-yes p62 and c-erbB-2 products and p53. These 79 tumors were divided into 2 groups: 32 benign (2 adenosis, 7 simple adenomas, 14 complex adenomas, and 9 benign mixed mammary tumors) and 47 malignant tumors (26 simple adenocarcinomas, 7 complex adenocarcinomas, 5 solid carcinomas, 2 sclerosing carcinomas, 6 malignant mixed mammary tumors, and 1 malignant myoepithelioma). As a result of immunostaining, 40.6% (13/32) of the benign tumors and 21.3% (10/47) of the malignant tumors expressed the c-Yes oncogene product, ErbB-2 expression was detected in 50% (16/32) of the benign tumors and in 19.1% (9/47) of the malignant tumors. P53 expression was detected in 16% (4/25) of the benign tumors and in 30.6% (11/36) of the malignant tumors. Co-expression of c-Yes and ErbB-2, ErbB-2 and p53, and all 3 products was detected in 6, 1 and 7 tumors, respectively.

Animals↗
PubMed1999

Subacute massive necrotizing myocarditis by canine parvovirus type 2 infection with diffuse leukoencephalomalacia in a puppy.

Severe necrotizing myocarditis associated with canine parvovirus type 2 (CPV-2) infection and diffuse leukoencephalomalacia was recognized in a 4-week-old mongrel puppy. The cardiac lesions were characterized by severe diffuse myocardial degeneration and necrosis with occasional massive mineralization and distinct intranuclear inclusion bodies. Immunohistochemical examination revealed the presence of CPV-2 antigens in both the cytoplasm and nuclei of the myocytes. In the white matter of the cerebrum, moderate to severe diffuse necrosis with diffuse infiltration of gitter cells and occasional diffuse mineral deposits were recognized symmetrically and bilaterally. In the meningocortical area of the cerebellum, there was mild focal hemorrhage and accumulation of hemosiderin-laden histiocytes. In addition to the absence of viral antigen (as judged by immunohistochemistry), neither viral inclusions nor other vascular lesions were identified in examined sections of brain. These findings suggest that the brain lesions were not induced by direct CPV-2 infection but were related to severe myocardial lesions producing prolonged hypoxia and/or ischemia.

Animals↗
PubMed1998

2-Hydroxyadenine, a mutagenic form of oxidative DNA damage, is not repaired by a glycosylase type mechanism in rat organs.

Oxygen radicals are known to play a role in causing cellular DNA damage, which is involved in carcinogenesis. 8-Hydroxyguanine (8-OH-Gua) is a major form of oxidative DNA damage and is known as a useful marker of DNA oxidation. Recently, we found another type of oxidative DNA damage, 2-hydroxyadenine (2-OH-Ade), which has a mutation frequency comparable to that of 8-OH-Gua. We compared the repair activities for two types of oxidative DNA damage, 8-OH-Gua and 2-OH-Ade, in 7-week-old male Sprague-Dawley (SD) rat organs. The repair activities were measured by an endonuclease nicking assay using 22 mer [32P]-end-labeled double-stranded DNA substrates, which contained either 8-OH-Gua (opposite C) or 2-OH-Ade (opposite T or C). In all of the SD rat organs we studied, the nicking activity for 2-OH-Ade was not detected, while that for 8-OH-Gua was clearly detected with the same conditions. Moreover, the 2-OH-Ade nicking activity was not induced in Wistar rat kidney extracts prepared after ferric nitrilotriacetate (Fe-NTA) treatment, which is known to increase 8-OH-Gua repair activity. These results suggest that 2-OH-Ade might not be repaired by the glycosylase type mechanism in mammalian cells.

Animals↗
PubMed1998

The human homolog of Saccharomyces cerevisiae CDC45.

In budding yeast Saccharomyces cerevisiae CDC45 is an essential gene required for initiation of DNA replication. A structurally related protein Tsd2 is necessary for DNA replication in Ustilago maydis. We have identified and cloned the gene for a human protein homologous to the fungal proteins. The human gene CDC45L is 30 kilobases long and contains 15 introns. The 16 exons encode a protein of 566 amino acids. The human protein is 52 and 49.5% similar to CDC45p and Tsd2p, respectively. The level of CDC45L mRNA peaks at G1-S transition, but total protein amount remains constant throughout the cell cycle. Consistent with a role of CDC45L protein in the initiation of DNA replication it co-immunoprecipitates from cell extracts with a putative replication initiator protein, human ORC2L. In addition, subcellular fractionation indicates that the association of the protein with the nuclear fraction becomes labile as S phase progresses. The CDC45L gene is located to chromosome 22q11.2 region by cytogenetics and by fluorescence in situ hybridization. This region, known as DiGeorge syndrome critical region, is a minimal area of 2 megabases, which is consistently deleted in DiGeorge syndrome and related disorders. The syndrome is marked by parathyroid hypoplasia, thymic aplasia, or hypoplasia and congenital cardiac abnormalities. CDC45L is the first gene mapped to the DiGeorge syndrome critical region interval whose loss may negatively affect cell proliferation.

Amino Acid Sequence↗
PubMed1998

Effects of forced and spontaneous exercise on 8-hydroxydeoxyguanosine levels in rat organs.

We investigated the effects of forced and spontaneous exercise on the levels of 8-hydroxydeoxyguanosine (8-OH-dG), a form of oxidative DNA damage, in rat organs (heart, lung, and liver). Rats were randomly assigned to one of three groups: forced exercise group (F), spontaneous exercise group (S), and sedentary control group (C). The mean levels of 8-OH-dG in the F group were 1.9-, 2.1-, and 2.4-fold higher in the heart, lung, and liver DNA, respectively, than in the S group. In the S group of rats, the distance run was not significantly correlated to the 8-OH-dG levels in the heart, lung, and liver DNA. These results demonstrate that the intensity of exercise is an important determinant in DNA damage, and suggest that spontaneous physical exercise is beneficial for maintaining a low level of oxidative DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1998

Expression of vascular endothelial growth factor in human hepatocellular carcinoma.

Vascular endothelial growth factor (VEGF) is thought to take an important role in tumor angiogenesis. The present study examined VEGF expression immunohistochemically in hepatocellular carcinomas (HCCs) in various histological grades and sizes. In HCCs that were composed of cancerous tissues of single histological grade, VEGF expression was the highest in well-differentiated HCCs, followed by moderately differentiated HCCs, and then poorly differentiated HCCs. VEGF positivity gradually decreased with the increase in tumor size. In the nodules larger than 3.0 cm, 36.8% were VEGF-negative. In HCCs consisting of cancerous tissues of two different histological grades, the expression was less intensive in the higher-grade HCC component. VEGF was not expressed in sarcomatous areas, while VEGF was expressed in the surrounding HCC tissues. The expression was also remarkable in the noncancerous tissues in which inflammatory cell infiltration was apparent. VEGF expression was also examined in six HCC cell lines. In reverse-transcription polymerase chain reaction (RT-PCR) analysis, expressions of the two secretion types (VEGF121 and VEGF165) were the highest. Thus, VEGF protein in culture supernatant was measured by using enzyme-linked immunosorbent assay (ELISA) with or without inflammatory cytokines, i.e., interleukin (IL)-1beta, interferon (IFN)-alpha, IFN-gamma, and tumor necrosis factor (TNF)-alpha; and growth factors, i.e., epidermal growth factor (EGF), platelet-derived growth factor (PDGF)-BB, basic fibroblast growth factor (bFGF), and transforming growth factor (TGF)-alpha. As a result, secretion of VEGF from the cell lines was upregulated at various degrees. Based on these findings, VEGF expression in HCC tissues was thought to be related to the histological grade. The findings also indicate that various cytokines and growth factors could cooperatively act to enhance VEGF expressions in HCC.

Aged↗
PubMed1998

Aminopeptidase N in sera of healthy subjects is a different N-terminal processed derivative from the one obtained from maternal serum.

A major aminopeptidase present in normal human serum was purified to homogeneity as a 150-kDa molecular species. Western blotting confirmed the binding of an anti-aminopeptidase N antibody to the protein. The N-terminal amino acid sequence of the enzyme was determined. The first 13 amino acids of the enzyme completely matched amino acids 59-71 of the sequence predicted from the human intestinal aminopeptidase N cDNA nucleotide sequence. As reported previously, aminopeptidase N from maternal serum had 68 fewer amino acid residues at the N-terminus than the enzyme obtained from detergent-solubilized membranes. The results indicate that aminopeptidase N in normal serum is a different N-terminal processed derivative from that obtained from maternal serum.

Amino Acid Sequence↗
PubMed1998

Leiomyosarcoma of the inferior vena cava. Resection and reconstruction of the renal vein using the gonadal vein.

We succeeded in surgically resecting a leiomyosarcoma of the inferior vena cava (IVC), which originated at the confluent portion of the right renal vein (RRV), together with the IVC and RRV, and also were able to preserve the right kidney by reconstructing the RRV with end-to-end anastomosis using the right gonadal vein. A good blood flow of the reconstructed RRV was thereafter confirmed by color Doppler ultrasonography, and the renal function was also satisfactory. This new procedure, a reconstruction of the RRV using the gonadal vein, has not been previously reported, but is considered to be an easy and effective method which enables the surgeon to preserve the normal right kidney.

Aged↗
PubMed1998

Laparoscopic management of indeterminate renal cysts.

OBJECTIVES: We present our follow-up of patients with indeterminate renal cysts who were initially evaluated laparoscopically. We specifically address those patients discovered to have cystic renal cell carcinoma by laparoscopy and the incidence of tract seeding, local recurrence, and distant metastases. METHODS: Between July 1993 and September 1997, 35 patients with indeterminate renal cysts were evaluated laparoscopically. Under laparoscopic visualization, the cyst was located and aspirated, the fluid was sent for cytology, and the floor of the cyst was biopsied. The tissue was then evaluated immediately by one of our genitourinary pathologists, and an intraoperative decision was made. Four patients were found to have cystic renal cell carcinoma and underwent partial or radical nephrectomy in the same setting. An additional patient had a delayed partial nephrectomy 10 days after laparoscopy as a result of change in the final pathology reading. The patients with malignancy were followed with chest x-ray, liver function tests, abdominal computed tomography (CT) scans, and physical examination every 3 months for the first year and then every 6 months thereafter. The average follow-up was 20.2 months (range 8 to 30). RESULTS: Of the 35 patients evaluated in this manner, 5 (14%) were found to have cystic renal cell carcinoma. There has been no evidence of local recurrence or metastatic disease to date. Physical examinations, chest x-rays, liver function tests, and abdominal CT scans all remain negative. CONCLUSIONS: Initial laparoscopic evaluation of complex cysts can save the patient from undergoing needless open surgery. Laparoscopic biopsy of cystic renal cell carcinoma followed by open surgery does not seem to increase the incidence of peritoneal seeding, tract recurrence, or distant metastases. Although the preliminary results are very encouraging, long-term follow-up is clearly necessary.

Adolescent↗
PubMed1998

Reduction of 8-hydroxyguanine in human leukocyte DNA by physical exercise.

We investigated the effect of physical exercise on the level of 8-hydroxyguanine (8-OH-Gua), a form of oxidative DNA damage, and its repair activity in human peripheral leukocytes. Whole blood samples were collected by venipuncture from 21 healthy male volunteers (10 trained athletes and 13 untrained men), aged 19-50 years, both before and after physical exercise. Trained athletes showed a lower level of 8-OH-Gua (2.4+/-0.5/10(6) Gua, p = 0.0032) before exercise when compared to that of untrained men (6.2+/-3.5). The mean levels of 8-OH-Gua of untrained subjects decreased significantly (p = 0.0057) from 6.2+/-3.5/10(6) Gua (mean+/-SD/10(6) Gua) to 3.3+/-1.4/10(6) Gua after physical exercise. On the other hand, the mean levels of repair activity of untrained subjects significantly increased after exercise (p = 0.0093) from 0.037+/-0.024 (mean DNA cleavage ratio+/-SD) to 0.056+/-0.036. In the trained athletes 8-OH-Gua level and its repair activity were not changed before and after the exercise. We also observed inter-individual differences in 8-OH-Gua levels and its repair activities. These results suggest that physical exercise causes both rapid and long-range reduction of oxidative DNA damage in human leukocytes, with individually different efficiencies.

Adult↗
PubMed1998

Peripheral neuroblastoma and primitive neuroectodermal tumor in Japanese black cattle.

Peripheral neuroblastoma was found in a 1-year-old, male, Japanese black cattle (Case 1) and primitive neuroectodermal tumor was noted in 7-year-old, female, Japanese black cattle (Case 2). In Case 1, neoplastic tissue was replaced the right cranial vault and nasopharynx. A large, soft mass approximately 18 cm in diameter was also observed in the right mandibulopharyngeal area. In Case 2, a neoplastic mass of about 15 cm in diameter was found in the mandibulopharyngeal area. Histopathologically, massive necrosis showing a pseudopalisade arrangement was frequently observed in Case 1. On the contrary, Homer & Wright rosette formations of tumor cells were prominent in Case 2. Immunohistochemically, the proliferating cells in Case 1 were positive for vimentin, S-100, and neurofilament (NF) and those in Case 2 showed intense immunoreactivity for NF and neuron specific enolase, but were negative for vimentin and S-100. The different degrees of differentiation of the neoplastic cells originating from the neuroectoderm, might be reflected in their different morphological and immunohistochemical features.

Animals↗
PubMed1997

Mitosis specific serine phosphorylation and downregulation of one of the focal adhesion protein, paxillin.

Mitotic cells typically lack well-formed focal adhesions. As an approach to explore the dynamic process regulating the focal adhesion assembly, we examined states of focal adhesion proteins during mitosis of the cell cycle. We found that the amount of paxillin was significantly reduced during mitosis of the cell cycle, whereas other focal adhesion proteins including talin, vinculin and Focal Adhesion Kinase did not. Proteolytic degradation appeared to be involved in the mitotic reduction, but transcriptional and/or translational controls of the mRNA were not essential for this downregulation. Moreover, concurrent with the decreased protein level, phosphorylation status of paxillin altered during mitosis; mitotic paxillin was phosphorylated primarily on serine and dephosphorylated on tyrosine while interphase one was phosphorylated both on serine and tyrosine. We found that mitotic phosphorylation created an electrophoretically slow-migrating population of paxillin which was barely detected in interphase cells. This mitotic specific modification occurred with both alpha and beta isoforms of paxillin. We also examined the fate of paxillin protein by changing its protein amount. We found that majority of paxillin overexpressed was subjected to the specific modification but not to the downregulation in the mitotic arrested cells. On the other hand, paxillin exogenously expressed at a moderate level was subjected to both the mitotic modification and downregulation. Collectively, we concluded that paxillin's specific serine phosphorylation together with the proteolytic downregulation of a limited fraction of paxillin is taken place during the mitosis of the cell cycle.

Animals↗
PubMed1997

Vitamin E inhibits apoptosis, DNA modification, and cancer incidence induced by iron-mediated peroxidation in Wistar rat kidney.

We have developed an experimental model of iron-induced oxidative nephrotoxicity and renal cancer. Using this model, the effect of vitamin E, a known antioxidant, was investigated. Three-week-old male Wistar rats were fed with vitamin E-sufficient (control) and vitamin E-supplemented diets throughout the experiment. After 1 month of feeding, iron-induced tissue lipid peroxidation, apoptosis, and formation of 8-hydroxydeoxyguanosine, a known DNA oxidative modification, were observed by cold Schiff staining, in situ labeling method (staining by terminal deoxynucleotidyl transferase-mediated nick end labeling), and high-performance liquid chromatography with electrochemical detection system, respectively, in the groups of rats treated with ferric nitrilotriacetate (Fe-NTA; Fe, 10 mg/kg body weight). For the vitamin E intervention study on Fe-NTA-induced renal carcinogenesis, two groups of rats fed vitamin E-sufficient and vitamin E-supplemented diets (30 and 20 rats, respectively) were treated with Fe-NTA (Fe, 7.5 mg/kg body weight once or twice a week) i.p. for 3 months and observed for 9 additional months. Five of the vitamin E-sufficient rats died during the first 3-month period. The results showed that vitamin E could inhibit tissue lipid peroxidation, apoptosis, 8-hydroxydeoxyguanosine formation, and the development of cancer [11 of 25 rats (44%) for vitamin E-sufficient versus 1 of 20 rats (5%) for vitamin E-supplemented rats, respectively]. These studies strongly suggest that in Fe-NTA-induced renal cancer, as with certain other types of cancer, oxidative stress plays an important role in carcinogenesis, and an antioxidant is an effective chemopreventive measure.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1997

Immunohistochemical study of constituents other than beta-protein in canine senile plaques and cerebral amyloid angiopathy.

To clarify the significance of the constituents of canine senile plaques (SPs) or cerebrovascular amyloid deposits, paraffin and cryostat sections of canine brains were examined by immunohistochemistry using antibodies against cathepsin B (CB), cathepsin D (CD), cystatin C (CC), alpha-1-antichymotrypsin (ACT), heat shock protein 70 (HSP70), ubiquitin (Ubq), and apolipoprotein E (Apo E). On the cryostat sections, all types of canine SPs and cerebrovascular amyloid deposits in both arterioles and capillaries were positive for Apo E. On paraffin sections, the Apo E immunoreactivity of diffuse plaques was weak and varied according to the method of fixation or pretreatment before immunostaining. Moreover, amyloid plaques were found to contain several elements that were positive for CC, ACT, CD, and Ubq, and a subset of vascular amyloid deposits around cortical capillaries showed significant immunoreactivity for CD, CC, and ACT. In addition, vascular amyloid deposits in the arterioles showed moderate CD immunoreactivity and were intensely Apo E positive. No significant labeling of canine Sps or vascular amyloid deposits was detected when the antibodies against CB and HSP 70 were applied to the cryostat and paraffin sections. These results indicated that, of the constituents examined, Apo E might be most closely related to canine beta-amyloidosis in the early stage of this brain disorder.

Amyloid beta-Peptides↗