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Biomedical subjects

K Ohno

Publications and source records attributed to K Ohno.

At least 397 records · Page 22Linked to original sources
PubMed1994

Up-regulation of ERK (MAP kinase) and MEK (MAP kinase kinase) transcription after rat facial nerve transection.

Up-regulation of ERK (extracellular signal-regulated kinase or MAP kinase) and MEK (ERK kinase or MAPK kinase) expression after rat facial nerve injury was demonstrated by in situ hybridization histochemistry and immunohistochemistry. These two enzymes play roles in one of the major intracellular signal cascade pathways involving receptor tyrosine kinase common to growth factor receptors, and transcription factors. Significant increases in ERK1 mRNA levels were observed from day 3 after facial nerve transection, with the highest level of expression from 1 to 2 weeks after the operation. This high level of mRNA expression then decreased gradually to the normal level. ERK1-like immunoreactivity showed a similar time course to that of its mRNA expression; however, the decay profile was more prolonged. The up-regulation of MEK, the ERK kinase/MAPK kinase, was also detected by immunohistochemistry. The protein expression profiles were almost equivalent, but the MEK expression was slightly advanced, suggesting that the observed up-regulation of MEK was not due to that of ERK. The receptor tyrosine kinase signal transduction pathway via MEK-ERK located downstream of growth factor receptors seems vital as a regulator of the synthesis of molecules that play important roles in the recovery process following injury or/and regeneration.

Animals↗
PubMed1994

The orientation of primary cilia during the wound response in 3Y1 cells.

The behavior of the primary cilia of 3Y1 cells in the interphase was investigated by indirect immunofluorescence microscopy and transmission electron microscopy, using an antibody for tubulin. At 4.5 h after scraping a part of a confluent cell sheet, the primary cilia of cells facing the wound were located predominantly forward of the nucleus on the wounded side, and were oriented in the direction of the leading lamellae. Cytoplasmic microtubules (MTs), emanating from around the base of the cilia, were well developed in the leading lamellae on the wounded side. On the other hand, in the cells of an unperturbed area away from the wounded edge, the primary cilia remained randomly distributed near the nucleus. The position and a certain well-defined orientation of a pair of centrioles seem to play an important role for the development of cytoplasmic MTs, and consequently the orientation of the centrioles is controlled by the primary cilia.

Animals↗
PubMed1994

Histomorphometric examination of healing around hydroxylapatite implants in 60Co-irradiated bone.

The purpose of this study was to histomorphometrically evaluate the use of hydroxylapatite (HA) implants in 60Co-irradiated bone. HA implants were installed in rabbit mandibles 3 months, 6 months, and 12 months after 15-Gy irradiation. Nonirradiated rabbits served as controls. The rabbits were killed 7, 14, 30, 60, and 90 days after the HA implantation. The histologic features of the healing process were examined and histomorphometric measurements were made to quantify the percentage of HA-bone contact and trabecular bone in the medullary cavity. In the irradiated groups, although HA-bone contact was observed later than that in the controls, recovery increased with time after irradiation and the rate of HA-bone contact bone-contacting implant surface ratio; BCSR exceeded 90% in all groups examined before 90 days. In the radiated groups, the average trabecular bone-specific volume was lower than that in the controls and began to decrease before BCSR exceeded 90%. Based on the present data, as well as data from the literature, it is suggested that the success rate of HA implants in irradiated bone increases with the interval after radiotherapy. It is also recommended that HA implants in irradiated bone be installed so that bearing by the cortical bone is increased.

Animals↗
PubMed1994

Assessment of contact sensitivity of four thiourea rubber accelerators: comparison of two mouse lymph node assays with the guinea pig maximization test.

Contact sensitivity of four thiourea rubber accelerators, diphenylthiourea (DPTU), dilaurylthiourea (DLTU), dibutylthiourea (DBTU) and diethylthiourea (DETU), was evaluated by a new sensitive mouse lymph node assay (SLNA) and the murine local lymph node assay (LLNA). The results of the SLNA and LLNA were compared with the data of the guinea pig maximization test (GPMT). In the LLNA and SLNA, the sensitizing activity was measured as a function of draining lymph node activation following application of the test chemicals. Of these four thioureas, three (DETU, DBTU and DPTU) were not classified as skin sensitizers in the LLNA. The SLNA successfully detected the sensitivity of all thioureas tested. This result indicated that the SLNA was, in these cases, more sensitive than the LLNA for identification of contact allergens. The order of sensitization potential observed from the SLNA was DPTU (greatest), DLTU, DBTU and then DETU (least). The predictions of sensitizing potential and the order of the sensitizing capacity of four thioureas by the SLNA and the GPMT are very similar.

Administration, Topical↗
PubMed1994

Gene regulation of cyclic AMP-dependent protein kinase subunits (C alpha, beta; RI alpha, beta and RII alpha, beta) in rat facial motoneurons after nerve transection.

In this study we investigated the changes in gene expressions of catalytic (C alpha, beta) and regulatory (RI alpha, beta and RII alpha, beta) subunits of cAMP-dependent protein kinase (PKA) in axotomized facial motoneurons of the rat. Nerve transection induced changes in the expression of C subunit messenger RNAs and RII subunit messenger RNAs. Control facial motoneurons had a high expression of both C alpha and C beta subunit messenger RNAs, but their expression declined after axotomy. The decrease was most pronounced at postoperative week 2 and returned to basal level within postoperative week 4. In contrast, the expression of both RII alpha and beta subunit messenger RNAs, which were low in control facial motoneurons, was increased after axotomy. Enhancement of RII subunits messenger RNAs was apparent during postoperative weeks 1 and 3, and then returned to the basal level. RI alpha, beta subunits messenger RNAs were strongly expressed in normal facial motoneurons, but were not clearly influenced by axotomy. These results indicate an attenuation of total PKA activity in axotomized facial motoneurons. Furthermore, such gene regulation may imply a change of the targets for PKA in facial motoneurons during the process of neurite regeneration.

Animals↗
PubMed1994

Up-regulation of GAP-43 (B50/F1) gene expression in vestibular efferent neurons following labyrinthectomy in the rat: in situ hybridization using an alkaline phosphatase-labeled probe.

Growth-associated protein (GAP)-43 plays a significant role in nerve regeneration and synaptic remodeling. We examined the profiles of GAP-43 mRNA expression in vestibular efferent neurons after labyrinthectomy in adult rats, and clearly demonstrated that labyrinthectomy increased GAP-43 expression in these neurons. This finding suggests the ability of vestibular efferent nerves to regenerate after nerve injury.

Alkaline Phosphatase↗
PubMed1994

Establishment of new inbred strains derived from Japanese wild rats (Rattus norvegicus).

Inbreeding of Japanese wild rats (Rattus norvegicus) resulted in five new strains. The conception rates of wild rat strains were lower than those of inbred laboratory strains, and maternal aggressiveness was observed in some wild strains. The body size of domesticated animals was larger than that of captured ancestors. Two strains have been established as inbred strains; the MITA strain has been tamed to the level of laboratory rats, while the nature of the MITD strain is wild. The MITB strain was derived from the MITA strain as a coat color variant. The MITC and MITE strains have been bred to the F15 and F11 generations, respectively. The new strains can provide new genetic variations against a wild type background and might be useful for physiological and psychological experiments.

Animals↗
PubMed1994

Amyloid beta protein precursor with Kunitz-type protease inhibitor domains (APPI) in cerebrospinal fluid and APPI mRNAs in cultured skin fibroblasts of patients with Alzheimer's disease.

We studied amyloid beta protein precursor with Kunitz-type protease inhibitor domains (APPI) concentration in cerebrospinal fluid (CSF) and APPI mRNA in skin fibroblast in Alzheimer's disease (AD). The subjects consisted of AD, cerebrovascular dementia (VD) and age-matched controls. We measured the APPI concentration in the CSF by the trypsin antibody sandwich ELISA. APPI mRNA was examined by the RT-PCR technique. The CSF APPI concentration in AD was significantly higher than that of VD and controls. The CSF APPI concentration in AD was high in the initial stage of dementia and decreased during the course. The expression of APPI mRNA in skin fibroblasts in AD was also significantly higher than that of VD and controls. These results suggest that measurements of APPI levels in CSF and APPI mRNA in skin fibroblasts may be useful for early diagnosis of AD.

Aged↗
PubMed1994

Cryptic arteriovenous malformation of the choroid plexus of the fourth ventricle--case report.

A 54-year-old female presented with a cryptic arteriovenous malformation (AVM) of the choroid plexus of the fourth ventricle causing intraventricular hemorrhage. Computed tomography and magnetic resonance imaging disclosed the lesion near the fourth ventricle, but bilateral vertebral angiograms showed no abnormalities. The preoperative diagnosis was cavernous angioma. The mass was removed completely, and histological examination demonstrated an AVM of the choroid plexus. Vascular malformations of the choroid plexus of the fourth ventricle are extremely rare. The possibility of this lesion being the cause of primary intraventricular hemorrhage of unknown origin should always be considered.

Cerebral Angiography↗
PubMed1994

Reactions of bone tissue in old rats to three different implant materials.

This study compares the bone responses of old rats when implanted with hydroxyapatite ceramic (HAC)-coated titanium, high-density HAC, and uncoated titanium. Twelve two-year-old Wistar rats were used in this study. Cylindrical implants were placed into each tibia, and the animals were killed seven, 14, 28, or 56 days after implantation. Undecalcified sections were prepared and were then stained with toluidine blue. The healing process was examined histologically, and histomorphometric measurements were made with a computer-based image analyzer to quantify the percentage of implant-bone contact. The results indicated that the HAC-coated implants were superior to the uncoated titanium implants in relation to bone contact. In the cases where the bone-free surface of HAC coating was dissolved, macrophages were often seen on the surface of the implant. Although further longitudinal data are needed to evaluate the decrease of HAC coating, in this animal model, HAC-coated implants may be useful for osseous response in bones of poor quality.

Age Factors↗
PubMed1993

Characterization of the transport system of prostaglandin A2 in L-1210 murine leukemia cells.

Prostaglandin (PG) A2 has been shown to be actively incorporated into mammalian cells and transferred to the cell nucleus. To characterize the properties of the PGA2 transfer system, we examined the status of PGA2 in L-1210 cells with modified cellular glutathione (GSH) levels. PGA2 in the cytosol fraction of the cells existed in its free-form, the GSH conjugate-form and a macromolecule associate-form (protein bound-form). When the GSH level was lowered under culture conditions, the amount of free-form increased while that of the protein bound-form was unchanged. When PGA2-loaded cells were incubated in a salt solution, free- and conjugate-forms were emitted from the cells. A concomitant decrease and increase of protein bound PGA2 in cytosol and nuclei, respectively, were observed. Subsequent studies with isolated cellular fractions revealed that PGA2 bound to cytosolic protein was transported into the nuclear interior in a temperature-dependent manner. The binding of PGA2 to the protein and subsequent transport to the nuclei were inhibited by PGJ2 and 4-hydroxy-cyclopentenone, but not by PGB2, PGD2, PGE2, PGF2 alpha, arachidonic acid or oleic acid. N-Ethylmaleimide (NEM) and p-chloromercuribenzoate (PCMB) strongly interfered with these transfer processes, suggesting that sulfhydryl components are involved in the transport of PGA2. Subfractionation of cytosol by gel chromatography proved the presence of two proteins (100-150 kDa and 25-35 kDa) that are capable of transporting PGA2 to cell nuclei. Though 40-45 kDa proteins, which correspond to GSH S-transferases, bound to PGA2, they lacked the nuclear transport activities.

Animals↗
PubMed1993

L-dopa induces Ca(2+)-dependent and tetrodotoxin-sensitive release of endogenous glutamate from rat striatal slices.

L-DOPA (10-1000 microM) concentration-dependently released glutamate (Glu) from superfused rat striatal slices. D-DOPA and dopamine (300 microM) produced no effects. The L-DOPA-induced release of Glu was not affected by 3-hydroxybenzylhydrazine (20 microM), an L-aromatic amino acid decarboxylase inhibitor. L-DOPA methyl ester (200 microM), a selective L-DOPA antagonist, antagonized the effect of L-DOPA in a competitive manner. Ca2+ deprivation and tetrodotoxin decreased L-DOPA (300 microM)-induced release of Glu. These findings indicate that L-DOPA induces a transmitter-like release of Glu via activation of a recognition site for itself.

Animals↗
PubMed1993

[Transcatheter hepatic segmental chemo-Lipiodol-embolization against hepatocellular carcinoma accompanied by tumor thrombosis in the portal vein].

We performed transcatheter hepatic segmental chemo-Lipiodol-embolization against hepatocellular carcinoma accompanied by tumor thrombosis in the portal vein. CT scan after embolization demonstrated good Lipiodol accumulation in the tumor thrombosis in some cases. In one resected case, remarkable necrosis of tumor thrombosis was proved histologically. In five non-resected cases, 6-month survival rate was 100%. We hope this therapeutic method can be useful for hepatocellular carcinoma with tumor thrombosis in the portal vein.

Aged↗
PubMed1993

Regulation of astrocyte proliferation by prostaglandin E2 and the alpha subtype of protein kinase C.

We found that astrocytes expressed the alpha subtype of protein kinase C. Treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) caused cultured astrocytes to proliferate. This effect of TPA was blocked by staurosporine, a potent protein kinase C inhibitor, suggesting the involvement of protein kinase C in astrocyte proliferation. Indomethacin, an inhibitor of prostaglandin formation, enhanced both the normal and TPA-induced proliferation of astrocytes. Authentic prostaglandin E2 blocked this effect of indomethacin and also partially blocked the effect of TPA, suggesting that the intracellular mechanisms involved in prostaglandin E2-regulated astrocyte growth might differ from those acting in protein kinase-dependent growth. The effect of prostaglandin E2 was blocked by a specific anti-prostaglandin E2 polyclonal antibody. Cultured astrocytes and microglia produced and released prostaglandin E2 in response to stimulants such as lipopolysaccharide, TPA, and lymphokines. Since the sensitivity of astrocytes and microglia to these stimuli was different, prostaglandin E2 may differentially regulate astrocyte proliferation under different physiological conditions, acting in an autocrine fashion for astrocytes and in a paracrine fashion for microglia.

Alkaloids↗
PubMed1993

[Usefulness of enhanced MR angiography by nitroglycerin].

We tried to use nitroglycerin to enhance MR angiography (MRA). Nitroglycerin has an effect to dilate vessels. We made a direct comparison between pre and post enhanced MRA (3 D-TOF technique). MRA after administration of nitroglycerin could depict more details of cortical branches without enhancement of background. So we recommend this method to be used in any examination of MR angiography.

Adult↗
PubMed1993

[Effect and complications of embolization therapy using absolute ethanol for renal arteriovenous malformation].

Transcatheter embolization therapy using absolute ethanol was accomplished in six patients with renal arteriovenous malformation. The effect of this therapy was considered to be good, because none of the patients has experienced recurrent hematuria. It is necessary to avoid the back flow of absolute ethanol. One patient had the particular complication of hydronephrosis caused by the incidental injection of absolute ethanol into the ureteral artery.

Adult↗