Biomedical subjects

Nobuo Sasaki

Publications and source records attributed to Nobuo Sasaki.

At least 37 records · Page 2Linked to original sources

PubMed2004

Effects of dopamine, dobutamine, amrinone and milrinone on regional blood flow in isoflurane anesthetized dogs.

The effects of cyclic AMP increasing cardiotonics (dopamine, dobutamine, amrinone and milrinone) on the blood flow in most organs were compared using colored microsphere technique in isoflurane-anesthetized dogs. Dopamine increased blood flow in ventricular myocardium. Furthermore dopamine induced the increase in blood flow in intestine and kidney at low to middle dose, but not at high dose. Dobutamine induced the highest increase in blood flow in ventricular myocardium and skeletal muscle among the drugs evaluated at middle and high doses. Amrinone and milrinone increased blood flow in ventricular myocardium almost same with catecholamines, and milrinone decreased vascular resistance moderately in most other organs. Milrinone might be more useful than catecholamines for improvement of congestive heart failure or peripheral circulatory failure accompanied with exceeded vasoconstriction.

Amrinone↗

PubMed2004

Prevalence of porcine endogenous retrovirus in domestic pigs in Japan and its potential infection in dogs xenotransplanted with porcine pancreatic islet cells.

The prevalence of porcine endogenous retrovirus (PERV) proviral DNA among various pig breeds raised in Japan was investigated by polymerase chain reaction (PCR). Moreover, potential infection of PERV was investigated by PCR and reverse transcriptase-polymerase chain reaction (RT-PCR) in experimentally induced diabetic dogs (n=5) implanted with the diffusion chamber type bio-artificial endocrine pancreas (Bio-AEP) containing porcine pancreatic endocrine (PE) cells. No immunosuppressant was used after the transplantation. PERV gag, pol, env-A and env-B genes were detected in any pigs examined. In two of three Landrace breeds, env-C gene was absent. PERV proviral DNAs and viral RNAs were also detected from the cultured porcine PE-cells. In the peripheral blood mononuclear cells and the spleen obtained at 6, 30, 32, 36, 79 weeks of xenotransplantation in dogs, however, no evidence of microchimerism, infection and viremia were confirmed. These results suggested that the risk of PERV infection through xenotransplantation of Bio-AEP containing porcine islet cells without immunosuppressants may be quite low.

Animals↗

PubMed2004

Establishment and characterization of four canine melanoma cell lines.

Four canine melanoma cell lines were established from the subcutaneous, oral gingival and mucosal melanoma tissues at the primary and metastatic sites. These cell lines were designated as CMeC-1, CMeC-2, KMeC and LMeC. The cells were spindles in shape, similar to that of primary tumor cells. The doubling times of these cells ranged from 34.1 +/- 5.61 to 57.9 +/- 3.28 hr and their chromosome number ranged from 46 to 80. When transplanted into nude mice, CMeC-1 and LMeC produced tumors, whereas CMeC-2 and KMeC did not. The morphology of the tissue formed by xenotransplantation of these cells was similar to their primary tumors.

Animals↗

PubMed2004

Secondary erythrocytosis associated with schwannoma in a dog.

An 11-year-old, spayed female mixed-breed dog showed clinical signs of right forelimb lameness and pain by palpation around the neck. Radiography and computed tomography (CT) revealed an extradural mass at the 6th and 7th cervical vertebrae, which compressed the spinal cord. The mass was surgically removed and histopathologically diagnosed as schwannoma. The dog recovered her normal gait after hemilaminectomy and removal of the mass. Ten months after the surgery, the tumor recurred with absolute erythrocytosis and was surgically removed again. This removal temporarily resolved the erythrocytosis with a decrease in plasma erythropoietin (EPO) concentration. EPO protein was detected immunohistochemically in the tumor cells. Erythrocytosis in this dog may be caused by ectopic EPO produced in the schwannoma tissues.

Animals↗

PubMed2003

neurotic, a novel maternal neurogenic gene, encodes an O-fucosyltransferase that is essential for Notch-Delta interactions.

Notch signalling, which is highly conserved from nematodes to mammals, plays crucial roles in many developmental processes. In the Drosophila embryo, deficiency in Notch signalling results in neural hyperplasia, commonly referred to as the neurogenic phenotype. We identify a novel maternal neurogenic gene, neurotic, and show that it is essential for Notch signalling. neurotic encodes a Drosophila homolog of mammalian GDP-fucose protein O-fucosyltransferase, which adds fucose sugar to epidermal growth factor-like repeats and is known to play a crucial role in Notch signalling. neurotic functions in a cell-autonomous manner, and genetic epistasis tests reveal that Neurotic is required for the activity of the full-length but not an activated form of Notch. Further, we show that neurotic is required for Fringe activity, which encodes a fucose-specific beta1, 3 N-acetylglucosaminyltransferase, previously shown to modulate Notch receptor activity. Finally, Neurotic is essential for the physical interaction of Notch with its ligand Delta, and for the ability of Fringe to modulate this interaction in Drosophila cultured cells. We present an unprecedented example of an absolute requirement of a protein glycosylation event for a ligand-receptor interaction. Our results suggest that O-fucosylation catalysed by Neurotic is also involved in the Fringe-independent activities of Notch and may provide a novel on-off mechanism that regulates ligand-receptor interactions.

Animals↗

PubMed2003

Presence and primary sequence of a high-affinity IgG receptor on canine mastocytoma (CM-MC) cells.

Mast cells play a central role in IgE-dependent allergic responses. Although they have been reported to express only low-affinity IgG receptors and no high-affinity receptors (FcgammaRI), our recent study showed that canine mastocytoma CM-MC cells are activated by monomeric canine IgG, suggesting the presence of FcgammaRI on CM-MC cells. In the present study, we measured the affinity of canine IgG with CM-MC cells, determined the presence of the FcgammaRI protein and mRNA, and identified the cDNA sequence of it. The results showed that (7.5+/-3.1)x10(4) receptor molecules are expressed on a CM-MC cell with a Ka of (9.1+/-1.6)x10(7)M(-1) for binding to monomeric canine IgG. Canine IgG-conjugated beads precipitated an approximately 72-kDa surface protein, whose size is consistent with that of the FcgammaRI alpha subunit of humans and mouse. The expression of FcgammaRI mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR), and the cDNA encoding the FcgammaRI alpha subunit was found to be 84% and 78% similar to that of humans and the mouse, respectively. The predicted amino acid sequence was 72% and 63% identical, respectively. Canine mastocytoma CM-MC cells are therefore very useful for studying FcgammaRI-mediated signal transduction in mast cells.

Amino Acid Sequence↗

PubMed2003

The canine mast cell activation via CRP.

We report here canine mastocytoma-derived cell (CMMC) activation via two pentraxin, limulus- and human-CRP. Mast cell chemotaxis was measured by Boyden's blindwell chamber. To confirm that the cell migration was chemotactic, "checkerboard" analysis was performed. We used Fura-2 to investigate CRP-mediated cytosolic calcium elevation. To examine whether CRP-induced stimulation is mediated through G-proteins, CMMC were incubated with pertussis toxin (PTx) before use in chemotaxis assay and Ca(2+) mobilization. CMMC migration in response to CRP was both chemokinetic and chemotactic. Limulus-CRP induced a transient Ca(2+)-mobilization dose-dependently. Preincubation of the cells with PTx inhibited CRP chemotaxis and Ca(2+)-mobilization, suggesting that G-proteins of the Gi-class are involved in the chemotaxis. We suggest that CRP may participate in the migration of mast cells to inflamed tissues during an acute-phase response. CRP-mediated recruitment of mast cells might play an important role in hypersensitivity and inflammatory processes.

Animals↗

PubMed2003

Role of CXCR4 and SDF-1 in mammary tumor metastasis in the cat.

It has recently been suggested that the chemokine receptor CXCR4 and its ligand SDF-1 (CXCL12) promote metastasis of various cancers in humans. Since feline mammary tumors also metastasize to distant organs frequently, we used real-time quantitative PCR to examine the expression of feline CXCR4 (fCXCR4) in ten feline mammary tumor cell lines and seven feline mammary tumor tissues, and also the expression of feline SDF-1 (fSDF-1) in various organs. Cell lines derived from metastatic regions expressed more fCXCR4 than those derived from primary tumors. Mammary tumor tissues overexpressed more fCXCR4 than normal mammary tissues. Organs with high levels of fSDF-1 expression represent common sites of metastasis. Migration assays using the feline mammary tumor cell line NAC were also performed to test the activity of TN14003 and TC14012, antagonists of human CXCR4, to antagonize fCXCR4 expressed on NAC cells. TN14003 and TC14012 inhibited migration of NAC cells. We conclude that fCXCR4 may be a therapeutic target for feline mammary tumors.

Animals↗

PubMed2003

Cytotoxicity for porcine islet cells by complement of six animal species.

Complement-mediated cytotoxicity for porcine islet cells (PICs) was evaluated using sera of six animal species. Then soluble complement receptor type-1 (sCR1) as an anti-complement agent was added to those sera, and the changes in 50% hemolytic unit of complement serum (CH50) and cytotoxic effect of those sera on PICs were examined. All the sera except for that of pig showed cytotoxicity. However, the extent of toxicity was considerably different between species. In the rat and human serum, sCR1 significantly reduced CH50 and cytotoxicity, however in the dog serum, sCR1 had no suppressive effects. These results may suggest that complement contribute to humoral cytotoxicity for PICs as a main factor, and the compatibility of complement with PICs differs between animal species.

Animals↗

PubMed2003

Effects of midazolam-butorphanol, acepromazine-butorphanol and medetomidine on an induction dose of propofol and their compatibility in dogs.

The effects of acepromazine-butorphanol (AB), midazolam-butorphanol (MB) and medetomidine (Med) on the induction dose of propofol and their compatibility with propofol were evaluated in client-owned dogs. All premedications induced good to excellent sedation and the induction dose of propofol was considerably reduced. Of the tested premedicants, Med induced the deepest sedation and the most potent dose-sparing effect. Induction of anesthesia was excellent to good in all dogs except for one dog premedicated with MB. Most dogs premedicated with AB or MB showed temporary apnea. Although other adverse effects such as bradycardia or hypotension may also occur, premedication with MB, AB or Med is a valuable technique for the induction of anesthesia with propofol in dogs in a clinical setting.

Acepromazine↗

PubMed2003

Xenotransplantation of porcine pancreatic endocrine cells to total pancreatectomized dogs.

Xenotransplantation of porcine pancreatic endocrine (PE) cells in a diffusion chamber, a bioartificial endocrine pancreas (Bio-AEP), was conducted to total pancreatectomized dogs. Six pancreatectomized dogs were divided into two groups of 3 dogs each. In three dogs of the control group, exogenous insulin was administered twice a day for 30 weeks to maintain fasting blood glucose (FBG) levels within the normal range. The remaining three dogs were implanted with Bio-AEPs (implantation group), in addition to daily insulin administration. In the implantation group, Bio-AEPs containing 1.3 to 1.8 x 10(7) cells per kg of body weight of the recipient were implanted without fixation into the abdominal cavity. In the control group, exogenous insulin requirements did not decrease during the experimental period, whereas it significantly decreased for a certain period (3, 11, 17 weeks) after implantation in all implanted dogs. In the implantation group, laparotomy was performed after FBG and the exogenous insulin requirement increased again and Bio-AEPs were removed. Two Bio-AEPs were completely destroyed, and the remaining one was encapsulated by thin fibrous tissue. In this dog, effusion was present within the capsule, but the Bio-AEP was not destroyed. Histopathologically, the necrosis, presumably caused by hypoxia, of the PE-cells was observed on transmission electron microscopy. In conclusion, Bio-AEP could function for a certain period after implantation in this study. However, more preclinical researches should be needed to apply this technique for the treatment of diabetic dogs.

Animals↗

PubMed2003

Molecular cloning of the feline telomerase reverse transcriptase (TERT) gene and its expression in cell lines and normal tissues.

Telomerase is a kind of reverse transcriptase which synthesizes and elongates telomeres. Telomerase activity is detected in many naturally occurring tumors and its expression appears to play an important role in the immortalization of tumor cells. In this study, cDNA encoding the feline telomerase reverse transcriptase (TERT) gene was cloned partially from a feline lymphoma cell line. The clone obtained in this study was 237 bp long including a reverse transcriptase motif 2, and was shown to have amino acid sequence similarity of 81.0% and 58.2% with human and mouse TERT cDNAs, respectively. TERT mRNA expression was detected in telomerase-positive cells (FL74, FT-1, 3201, FKNp, FONp, and FYMp), and was not detected in telomerase-negative cells (normal fibroblasts and CRFK). TERT mRNA was detected in various normal tissues including the spleen, pancreas, stomach, cerebrum, testis, bone marrow, lymph node and thymus, and relatively high-level expression was observed in the small bowel and large bowel. No expression of TERT mRNA was detected in the liver, adrenal gland, urinary bladder and lung. The TERT cDNA clone and the results obtained in this study will be useful for further investigation of feline tumors.

Amino Acid Sequence↗

PubMed2003

Clinical usefulness of propofol as an anesthetic induction agent in dogs and cats.

Propofol was used as an induction agent of general anesthesia in 77 dogs and 64 cats, all client owned, for a variety of surgeries/treatments or diagnostic procedures. The mean intravenous doses of propofol required to achieve endotracheal intubation in dogs and cats were 6.5 +/- 1.4 mg/kg and 10.1 +/- 2.8 mg /kg, respectively. Most of the animals could be induced to anesthesia smoothly by the administration of propofol with a high incidence of apnea. Propofol is a clinically valuable anesthetic induction agent in both dogs and cats, however, care must be taken for apnea.

Anesthesia, Intravenous↗

PubMed2003

Relative biological effectiveness and tolerance dose of fission neutrons in canine skin for a potential combination of neutron capture therapy and fast-neutron therapy.

To investigate the potential efficacy of fission neutrons from a fast-neutron reactor for the treatment of radioresistant tumors, the relative biological effectiveness (RBE) and tolerance dose of fission neutrons in canine skin were determined. The forelimbs of 34 healthy mongrel dogs received a single dose of fission neutrons (5.6, 6.8, 8.2, 9.6 or 11 Gy) or 137Cs gamma rays (10, 15, 20, 25 or 30 Gy). Based on observations of radiodermatitis for each radiation, the single-fraction RBE of fission neutrons in the sixth month was calculated as approximately 3. The tolerance doses of fission neutrons and gamma rays, defined as the highest doses giving no moist desquamation on the irradiated skin in the recovery phase, were estimated as 7.6 Gy and 20 Gy, respectively. The tolerance dose of 7.6 Gy of fission neutrons included 5.0 Gy of fast neutrons possessing high anti-tumor effects and 1.4 x 10(12) n/cm2 of thermal neutrons, which could be applicable to neutron capture therapy (NCT). The combination of fast-neutron therapy and NCT using a fast-neutron reactor might be useful for the treatment of radioresistant tumors.

Animals↗

PubMed2003

Molecular cloning of the canine telomerase reverse transcriptase gene and its expression in neoplastic and non-neoplastic cells.

OBJECTIVE: To perform molecular cloning of the canine telomerase reverse transcriptase (TERT) gene and determine its expression in neoplastic and non-neoplastic cells. SAMPLE POPULATION: 9 canine tumor cell lines derived from various neoplasms, 16 primary canine tumors, and tissues from 15 normal canine organs. PROCEDURE: Tumor cell lines were derived from canine tumors that included osteosarcoma, mammary gland adenocarcinoma, melanoma, acute lymphoblastic leukemia, lymphoma, and mastocytoma and a canine primary fibroblast culture. Canine TERT complementary DNA (cDNA) was amplified by use of polymerase chain reaction (PCR) and sequenced. Expression of TERT mRNA was examined by reverse transcription (RT)-PCR assay. Telomerase activity was measured by use of the telomeric repeat amplification protocol assay. RESULTS: The canine TERT cDNA clone was 237 base pairs in length and contained a central region encoding the reverse transcriptase motif 2. Expression of TERT mRNA was detected in canine tumor cell lines that had telomerase activity but not in telomerase-negative canine primary fibroblasts. The TERT mRNA was detected in 13 of 16 canine tumor tissues and several normal tissues such as liver, ovary, lymph node, and thymus. A significant correlation between TERT expression level and telomerase activity was noted. CONCLUSIONS AND CLINICAL RELEVANCE: Expression of TERT mRNA was closely associated with telomerase activity in neoplastic cells as well as some non-neoplastic cells from dogs. In addition to telomerase activity, expression of TERT mRNA can be used as a marker of tumor cells.

Animals↗

PubMed2003

Effect of an adenoviral vector that expresses the canine p53 gene on cell growth of canine osteosarcoma and mammary adenocarcinoma cell lines.

OBJECTIVE: To generate an adenoviral vector that expressed the canine p53 gene and investigate its growth-inhibiting effect on canine osteosarcoma and mammary adenocarcinoma cell lines. SAMPLE POPULATION: 2 canine osteosarcoma cell lines (HOS, OOS) and 3 canine mammary adenocarcinoma cell lines (CHMp, CIPm, and CNMm). PROCEDURE: An adenoviral vector that expressed the canine p53 gene (AxCA-cp53) was generated. p53 gene expression was examined by use of reverse transcription (RT)-polymerase chain reaction (PCR) assay and immunohistochemistry. Susceptibility of cell lines to the adenoviral vector was determined by infection with an adenoviral vector that expresses beta-galactosidase (AxCA-LacZ) and 3-indolyl-beta-D-galactopyranoside staining. Growth inhibitory effects were examined by monitoring the numbers of cells after infection with mock (PBS) solution, AxCA-LacZ, or AxCA-cp53. The DNA contents per cell were measured by flow cytometry analysis. Apoptotic DNA fragmentation was detected by use of a terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. RESULTS: AxCA-cp53-derived p53 gene mRNA and P53 protein were detected by RT-PCR analysis and immunohistochemistry, respectively. Multiplicity of infection at which 50% of cells had positive 3-indolyl-beta-D-galactopyranoside staining results ranged from 10 to 50. AxCA-cp53 induced growth inhibition in a dose-dependent manner. Arrest of the G1-phase population and apoptotic DNA fragmentation were observed in cells infected with AxCA-cp53. CONCLUSIONS AND CLINICAL RELEVANCE: AxCA-cp53 inhibits cell growth via induction of cell cycle arrest and apoptosis in canine osteosarcoma and mammary adenocarcinoma cell lines that lack a functional p53 gene. AxCA-cp53 may be useful to target the p53 gene in the treatment of dogs with tumors.

Adenocarcinoma↗

PubMed2003

Effect of adhesion or collagen molecules on cell attachment, insulin secretion, and glucose responsiveness in the cultured adult porcine endocrine pancreas: a preliminary study.

The effect of either adhesion or collagen molecules on cell attachment, insulin secretion, and glucose responsiveness was investigated in adult porcine pancreatic endocrine (PE) cells that were cultured for a longer term in vitro. Six different types of molecules--laminin, fibronectin, poly-L-lysine (PLL), type I collagen, gelatin, and Matrigel--were used. Approximately 2.0 x 10(5) cells per dish of each molecule type were cultured for 4 weeks. In the laminin group, the insulin accumulation was maintained at a significantly higher level than in the control group at 4 weeks of culture, and glucose-stimulated insulin secretion and the insulin-positive rate were also higher than in the control group. In the Matrigel group, islet-like cell clusters were formed, but insulin accumulation rapidly decreased at 3-4 weeks of culture. A large number of PE cells attached tightly and spread in the fibronectin group until the fourth week of culture, but their function was not better than those in the control group. In the PLL and gelatin groups, the PE cell function was not significantly different from that of the control group. In the type I collagen group, insulin secretion was inferior to that of the other groups. The results of this study suggest that laminin is the most suitable extracellular matrix for the long-term culture preservation of PE cells.

Animals↗

PubMed2002

Molecular and seroepidemiological evidence of canine calicivirus infections in Japan.

Calicivirus infection of dogs was epidemiologically investigated by using canine calicivirus (CaCV) strain 48 as a reference. Similar RNA polymerase gene sequences and neutralizing antibodies against CaCV were detected in 1.7% of clinical specimens and 57% of serum samples, respectively, suggesting a high prevalence of CaCV in dog populations.

Animals↗