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Biomedical subjects

K Ohno

Publications and source records attributed to K Ohno.

At least 829 records · Page 46Linked to original sources
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Recognition of novel amphiphiles with many pendent mannose residues by Con A.

Novel amphiphiles which carry many mannose residues as side chains were prepared by telomerization of N-methacryloylaminopropyl D-mannopyranoside (alpha:beta = 20:1), N-methacryloylaminohexyl D-mannopyranoside (alpha:beta = 20:1), or 3-(2-methacryloylaminoethylthio)propyl D-mannopyranoside (alpha:beta = 4:1) using a lipophilic radical initiator. The mannose-carrying amphiphiles incorporated in liposomes were recognized by a lectin from Canavalia ensiformis (Con A), which was proven by the increase in turbidity of the liposome suspension after mixing with Con A. The interaction between sugar residues on the liposome surface and the lectin was largely affected by the degree of polymerization (DP) and the surface density of the amphiphile in the liposomes. The distance between the sugar residues and the polymer main chain did not affect the specific recognition by the lectin significantly in the liposome system, whereas it appreciably affected the recognition in the water-soluble polymer system. The association constants (Ka) of the amphiphiles (DP approximately 18) with Con A (0.3-2.2 x 10(6) M-1 at 25 degrees C) were much larger than that of alpha-methyl D-mannopyranoside (8.2 x 10(3) M-1) due to the "cluster effect ". The positive entropy change (20-52 J/mol K) for the binding of Con A to mannose residues on the liposome surface showed that the recognition in the liposome system was largely promoted by the release of water molecules from both the sugar residues on the liposome surface and the binding site of Con A.

Amines↗
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Is the detection of anti-Rhipicephalus sanguineus (Rs24p) antibodies a valuable epidemiological tool of tick infestation in dogs?

Antibodies against the 24 kDa Rhipicephalus sanguineus (Rs24p) protein were detected by ELISA to evaluate the relationship between antibodies and tick infestation. The mean titer of 3 dogs that underwent 2 experimental infestations with adult ticks was transiently increased after the second infestation. There was a significant difference in mean titers between positive control dogs naturally infested with ticks and tick-naive dogs. These results suggested that anti-Rs24p antibodies detected by ELISA are a marker of tick exposure. There was no significant difference in mean titers between tick-naive dogs and seropositive dogs to Ehrlichia canis. Some dogs positive for E. canis antibodies showed, however, higher titers than most tick-naive dogs. R. sanguineus may be related to the E. canis infection in Japan.

Animals↗
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Detection of the integrated feline leukemia viruses in a cat lymphoid tumor cell line by fluorescence in situ hybridization.

Feline leukemia virus (FeLV) is a type-C retrovirus associated with lymphoid and hematopoietic malignancies in cats. The FeLV-induced tumors are thought to be caused, at least in part, by somatically acquired insertional mutagenesis in which the integrated provirus may activate a proto-oncogene or disrupt a tumor suppressor gene. This study was undertaken to enumerate and map the acquired proviral insertions in the genome of a feline thymic lymphoma cell line (FT-1) infected with FeLV. Fluorescence in situ hybridization (FISH) combined with tyramide signal amplification was applied on the chromosome specimen of FT-1 cells and normal cat lymphocytes, with an entire FeLV-A genome used as a probe. Specific hybridization signals were detected from only the metaphases of the FT-1 cells, not from those of normal cat lymphocytes. Statistically based on the Poisson's distribution, at least six loci of chromosomal regions, A2p23-p22, B2p15-p14, B4p15-p14, D4q23-q24, E1p14-p13, and E2p13-p12, appeared to be positive for FeLV integration. Consistently, Southern blot hybridization analysis using an FeLV LTR-U3 probe specific for exogenous FeLV showed the integration of at least six FeLV proviral genomes in FT-1 cells. The cytogenetic technique employed here will provide valuable molecular tags to reveal unidentified tumor-associated genes in FeLV-associated tumor cells.

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The expression of presenilin-1 mRNA in skin fibroblasts from Alzheimer's disease.

The presenilin-1 (PS-1) gene was recently identified as one of the causative genes in the early onset of familial Alzheimer's disease (AD). Analysis of the PS-1 gene is thought to be useful in clarifying the pathogenesis of AD. However, there have been few reports about the expression of the PS-1 gene in AD. In this study, we analyzed the expression of PS-1 mRNA in cultured skin fibroblasts taken from living patients with AD by Northern blot analysis. The subjects consisted of 18 cases with AD and 10 cases of neurological patients without dementia (CTL). We found that the PS-1 mRNA levels in AD were significantly higher than those in CTL (p < 0.01). Moreover, we found that the PS-1 mRNA level increases in the early stages of AD and tends to decrease in the advanced stages. These findings suggest that high levels of PS-1 mRNA may play an important role in developing AD.

Adult↗
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The expression of presenilin 1 mRNA in skin fibroblasts and brains from sporadic Alzheimer's disease.

We examined the expression of presenilin 1 (PS-1) mRNA in cultured skin fibroblasts taken from living patients with Alzheimer's disease (AD) and human brains taken postmortem from AD patients by RT-PCR analysis. The donors of fibroblasts consisted of 28 cases with AD and 19 neurological patient without dementia (CTL). The brains came from 17 cases with AD and 23 cases with CTL. We found that PS-1 mRNA levels in skin fibroblasts of AD patients were significantly higher than those of CTL patients (p < 0.0001). Moreover, we found that PS-1 mRNA levels in human brains with AD were significantly higher than in those with CTL (p < 0.0001). These findings suggest that high levels of PS-1 mRNA in AD may play an important role in developing AD and that the examination of PS-1 mRNA in skin fibroblasts may be helpful for the diagnosis of AD.

Aged↗
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Evaluation of the T&T olfactometer by mapping c-fos protein in an olfactory bulb.

OBJECTIVES: Although in Japan the T&T olfactometer is most commonly used in patients suffering from smelling disorders, no scientific analysis has been performed so far. The objective of this study was to clarify whether the five odorants used in the T&T olfactometer are suitable or not. We mapped the glomeruli activated by the five test odorants employed in the T&T olfactometer. The expression of c-fos protein as a marker of neuronal excitation was monitored using an immunohistochemical technique. STUDY DESIGN: The expression of c-fos protein in the rat olfactory bulb was investigated to determine what part of the olfactory system is activated by five odorants used in the T&T olfactometer. METHODS: Each rat was isolated in a clean cage for 120 min to reduce the basal expression of c-fos protein. Each rat was fixed in the cage and exposed to one of five test odorants for 90 min. The expression of c-fos protein was measured using an immunohistochemical technique. RESULTS: Each odorant activated numerous glomeruli and the patterns of distribution of activated glomeruli were specific to each odorant. Glomeruli in most regions of the bulb were activated by all five test odorants. CONCLUSION: We assume that in the T&T olfactometer the optimal ((five)) odorants are employed, because the glomeruli activated by those odorants showed unique patterns in the immunohistochemical assay.

Animals↗
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Analysis of amyloid precursor protein mRNAs in skin fibroblasts in Down's syndrome.

We examined amyloid precursor protein (APP) mRNAs expression in skin fibroblasts from Down's syndrome (DS) patients of different ages to determine the time of occurrence of abnormal splicing. The ratio of APP770 + 751 mRNA to APP695 mRNA (APP770 + 751/695) was significantly increased in the young DS group and adult DS group compared with the age-matched control groups (p < 0.01, p < 0.05), but no significant increase was observed in the aged DS group compared with the age-matched control group. These findings suggest that metabolic abnormalities of the APP gene occur at a very early stage of DS, at a mean age of about 5 years. Therefore, metabolic abnormalities of the APP gene are considered to appear at a very young age also Alzheimer's disease (AD). In this study, we confirmed that examination of the APP gene in skin fibroblasts might be useful for early diagnosis of AD.

Adult↗
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Changes in sequestered leukocytes and platelets in the pulmonary microvasculature of rats with monocrotaline-induced pulmonary hypertension.

The role of leukocytes (WBCs) and platelets (PLTs) in the pulmonary circulation may be important in the development of monocrotaline (MCT)-induced pulmonary hypertension in rats. We investigated the changes in WBCs and PLTs in the pulmonary microvasculature during the development of chronic pulmonary hypertension in MCT rats by real-time confocal scanning laser microscopy. The number of WBCs sequestered in the pulmonary microvasculature increased significantly from day 7 after MCT injection, but no further increase occurred from days 14-28. The number of PLTs sequestered in the pulmonary microvasculature increased significantly from day 7 after MCT injection, and reached a peak on day 14. However, the number of PLTs sequestered on days 21 and 28 after MCT injection was significantly lower than on day 14. These findings suggest that PLTs mainly contribute to the initial and middle stages of the development of MCT-induced pulmonary hypertension in rats, while WBCs mainly contribute to the middle and late stages.

Animals↗
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Brain edema during ischemia and after restoration of blood flow. Measurement of water, sodium, potassium content and plasma protein permeability.

The left cerebral hemisphere of Mongolian gerbils was used to elucidate the mechanisms of brain edema which develop during cerebral ischemia and after restoration of cerebral blood flow following temporary ischemia. Water content was measured by the tissue-drying method. Sodium and potssium ion concentration was measured by flame photometry. Passage of 131I-albumin (RISA) from blood to the cerebral parenchyma was measured on a gamma scintillation counter. Our findings indicate that pure cytotoxic edema develops during ischemia and during a short period after restoration of cerebral blood flow. Vasogenic edema, which is accelerated by the leakage of plasma constitutents from blood due to blood-brain barrier damage, developed after restoration of the cerebral blood flow. After less than 1 hr of ischemia, restoration of the cerebral blood flow drastically reduced the degree of brain edema. However, restoration of the cerebral blood flow greatly worsened the brain edema following more than 3 hr of ischemia.

Animals↗
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Effect of steroid on ischemic brain edema. Analysis of cytotoxic and vasogenic edema occurring during ischemia and after restoration of blood flow.

Mongolian gerbils were observed for the effects of beta-methasone on ischemic brain edema which developed during ischemia or after blood flow restoration. The severity of brain edema was determined by measuring water content of the ischemic cerebral hemisphere, using the wet and dry methods. Sodium and potassium ions were extracted from homogenized brains with 0.75N HNO2 and ion concentration measured by flame photometry. Passage of RISA from blood into the cerebral parenchyma, as an indicator of blood-brain barrier change, was determined with a gamma-scintillation counter. In the cytotoxic edema model, animals were killed after 9 h permanent ischemia or 3 h after 1 h ischemia. In the simultaneous cytotoxic and vasogenic edema model, the animals were killed either 20 h or 3 days following 1 h ischemia, or 3 h after blood flow restoration following 6 h ischemia. Steroid treatment was ineffective in ischemic brain edema of the cytotoxic or vasogenic type.

Animals↗
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Transient appearance of "no-reflow" phenomenon in Mongolian gerbils.

We investigated the existence of the "no-reflow" phenomenon in focal cerebral ischemia. Regional cerebral blood flow was studied in Mongolian gerbils perfused with a carbon-black particle suspension after cerebral ischemia prior to decapitation and compared with 14C-antipyrine autoradiographic images. The correlation between the occurrence of the "no-reflow" phenomenon and systemic arterial blood pressure change was also examined. We found that the phenomenon was transient in character and that its manifestation was related to the transient fall in arterial blood pressure observed immediately after clip release and with stagnation of venous blood flow. The phenomenon disappeared in animals in which the arterial blood pressure was artificially increased after clip release.

Animals↗
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Effect of hypertension on blood-brain barrier. Change after restoration of blood flow in post-ischemic gerbil brains. An electronmicroscopic study.

The effect of induced hypertension on the blood-brain barrier (BBB) change in Mongolian gerbils exposed to various periods of ischemia was studied. Evans blue dye was used to determine the BBB change in animals subjected to different levels of hypertension after 3 h ischemia. Horseradish peroxidase (HRP) was used in electronmicroscopic studies of animals subjected to 30 min, 1, 3 or 6 h ischemia and subsequently exposed for 30 min to varying periods and sequences of normo- and hypertension. Furthermore, HRP-labeled vesicle counts were performed in animals from the 30-min ischemia group. Our findings revealed that hypertension, after blood flow restoration following ischemia, induces and/or accelerates BBB damage by enhancing endothelial vesicular and/or tubulo-channel transport.

Animals↗
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Hematologic abnormalities and outcome of 16 cats with myelodysplastic syndromes.

We investigated the hematologic abnormalities and prognoses in 16 cats with myelodysplastic syndromes (MDS). Nonregenerative anemia, thrombocytopenia, and neutropenia were observed in 15, 13, and 4, respectively, of the 16 cats with MDS. Morphologic abnormalities characteristic of MDS included megaloblastoid rubricytes (9 cats), hyposegmentation of neutrophils (7 cats), nuclear abnormality of rubricytes (10 cats) and neutrophils (13 cats), and micromegakaryocytes (10 cats). Disease in these 16 cats was subclassified into refractory anemia (RA; 8 cats), RA with excess of blasts (RAEB; 5 cats), RAEB in transformation (RAEB in T; 1 cat), and chronic myelomonocytic leukemia (CMMoL; 2 cats), according to the human French-American-British (FAB) classification. In the cats in which the clinical outcome was known, 3 of 6 cats with high blast cell count MDS, including RAEB, RAEB in T, and CMMoL, developed acute myeloid leukemia, but only 1 of 8 cats with low blast cell count MDS (RA) developed acute myeloid leukemia. Based on the Dusseldorf scoring system for the prognosis of human MDS, the survival times of the cats showing high scores (> or =3 points) were significantly shorter than those of the cats with low scores (<3 points). The FAB classification and Dusseldorf scoring system were considered to be useful for predicting the prognosis of feline MDS. Furthermore, 15 of the 16 cats with MDS in this study were infected with feline leukemia virus, indicating its possible etiologic role in the pathogenesis of feline MDS.

Anemia↗
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Detection of UV-induced K-ras codon 12 mutation by PCR and differential dot-blot hybridization in cells from Down syndrome and Cockayne syndrome.

By means of the polymerase chain reaction (PCR) and differential dot-blot hybridization, base substitution mutations of K-ras codon 12 were investigated in skin fibroblast cells from Down syndrome (DS) patients. Mutations were identified in DS cells after UV irradiation, predominantly in cells from younger patients. In contrast, no mutation was detected in cells from Cockayne syndrome (CS) patients who had the same features of premature aging as in DS but were not prone to cancer. This association of DS cells, but not CS cells, with inducibility of the K-ras codon 12 mutation may imply the proneness of DS patients to cancer development but a lack of proneness of CS patients.

Aging↗
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Histomorphometric evaluation of the effect of hyperbaric oxygen treatment on healing around hydroxyapatite implants in irradiated rat bone.

The effect of hyperbaric oxygen (HBO) on the tissue reaction around hydroxyapatite (HA) implants in irradiated bone of rats was investigated. A single dose of 15 Gy was delivered to the right leg of 20 rats. HA implants were placed in the bilateral tibial proximal metaphysis 3 months after irradiation. HBO was administered to half of the rats before and after 15-Gy irradiation. The healing process was examined histologically and histomorphometrically. The results indicated that HBO slightly improved trabecular bone formation in the irradiated bone, accelerated bone remodeling in the nonirradiated bone, and improved HA-bone contact in both the irradiated and nonirradiated bones.

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