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Biomedical subjects

H Ohnishi

Publications and source records attributed to H Ohnishi.

At least 19 recordsLinked to original sources
PubMed1995

Ethnic segregation of HTLV-I and HTLV-II carriers among South American native Indians.

To investigate the genetic background of human T-cell leukemia virus type I (HTLV-I) and II (HTLV-II) carriers among South American native Indians, we analyzed HLA DRB1*-DQB1* haplotypes of the virus carriers from Andes highlands and Orinoco lowlands by the PCR-RFLP genotyping method. It was revealed that the HTLV-I-carrying Andes natives had one of the 5 HLA haplotypes: DRB1*-DQB1* 0403-0302, 0802-0402, 0901-0303, 1406-0302 and 0407-0302, and that the Orinoco HTLV-II carriers had one of the 3 HLA haplotypes: DRB1*-DQB1* 1402-0301, 1602-0301 and 0404-0302. The HLA haplotypes of Andes HTLV-I carriers and Orinoco HTLV-II carriers were mutually exclusive. The haplotypes associated with HTLV-I carriers were commonly found among the Andes Indians and Japanese, which is the known HTLV-I endemic population, while the haplotypes associated with HTLV-II carriers were specifically found among the Orinoco Indians and North American Indians, among whom HTLV-II is endemic. These results suggested that HLA haplotypes might be ethnically segregated among South American natives and might be involved in the susceptibility to HTLV-I and HTLV-II infections.

Alleles↗
PubMed1995

Homozygous deletions of p16/MTS1 gene are frequent but mutations are infrequent in childhood T-cell acute lymphoblastic leukemia.

Fifty-six primary childhood T-cell acute lymphoblastic leukemia (T-ALL) samples and 17 T-ALL cell lines were examined for mutations and homozygous deletions of the p16/MTS1 gene using polymerase chain reaction single-strand conformation polymorphism and Southern blot analysis. Homozygous deletions were found in 22 primary samples (39%) and in 10 cell lines (59%). In contrast, mutations including small deletions and/or insertions were identified in only 4 primary samples (7%) and in 2 cell lines (12%). Mutations included samples (7%) and in 2 cell lines (12%). Mutations included one nonsense mutation at codon 72, one missense mutation at codon 58, one deletion (29 bp from codon 52-61), one insertion (7 bp into codon 50), and two deletion/insertions (codon 63 and intron 1). Four of the six mutations caused subsequent stop codon and presumably produced truncated p16 protein. Our results suggest that p16 gene alterations are involved in the development of T-ALLs and that the inactivation of the p16 gene occurs mainly through homozygous deletions rather than mutations.

Base Sequence↗
PubMed1995

Regulation of hepatic genes and liver transcription factors in rat hepatocytes by extracellular matrix.

Culturing hepatocytes on different extracellular matrix (ECM) substrata including tissue culture plastic, type I collagen, Engelbreth-Holm-Swarm (EHS) gel and poly-N-p-vinylbenzyl-D-lactonamide (PVLA) regulated levels of mRNAs for cytoskeleton and liver-specific genes. In hepatocytes on EHS gel, the ratio of albumin/beta-actin in mRNA levels was high and serially increased during the culture period, while the ratio was low and declined in cells on plastic substratum, collagen or PVLA. The changes in cellular levels of albumin mRNA which were regulated by ECM corresponded with those in two liver-specific transcription factors, hepatocyte nuclear factors-1 and -4, which control the transcription of liver-specific genes. These results suggest that cell-matrix interaction may determine and maintain the differentiated phenotype of hepatocytes by regulating liver-specific transcription factors.

Actins↗
PubMed1995

CD28 cross-linking augments TCR-mediated signals and costimulates superantigen responses.

The CD28 molecule expressed on the surface of T cells plays a pivotal role in transducing costimulatory signals necessary for cell activation. CD28 coligation enhances tyrosine phosphorylation and phosphoinositol 3-kinase association in responsive cells. CD28 cross-linking has also been reported to activate inositol phospholipid turnover and to cause release of intracellular calcium. Here we examine the effects of CD28 cross-linking on early activation of protein kinase C (PKC). We have reported recently that either PMA or CD28 cross-linking synergizes with signals delivered by superantigen and cytokines to induce the proliferation of APC-depleted T cells. Unlike PMA, CD28 cross-linking alone failed to induce an increase in membrane-associated PKC activity. However, PKC activation was seen in resting T cells when CD28 was cross-linked in the presence of superantigen plus APC-derived supernatant, which by themselves had no effect on PKC activity. Inhibition of PKC activity using calphostin C blocked the response of pure T cells to superantigen in the presence of either autologous APC, PMA, or CD28 cross-linking. This effect was specific; it was only seen when calphostin C was added within the first hour of stimulation. Assays of [Ca2+]i levels showed that CD28 cross-linking augmented and prolonged the rise in [Ca2+]i induced in T cells by superantigen and APC-derived cytokines. In the presence of superantigen, the proliferative response of T cells costimulated by CD28 cross-linking was cyclosporin A-sensitive, whereas in the presence of PMA, CD28 cross-linking conferred resistance to cyclosporin A. Both the phosphorylation of phospholipase C gamma 1 at tyrosine and the rise in [Ca2+]i induced by CD28 cross-linking in preactivated T cells were blocked by herbimycin A. Herbimycin A treatment also blocked the ability of CD28 cross-linking to induce a rise in [Ca2+]i in resting T cells. We conclude that CD28 costimulatory signals augment superantigen-induced TCR signals by converging onto common TCR effector pathways involving the activation of phospholipase C gamma 1 and PKC and by generating a cyclosporin A-sensitive pathway.

Antigen-Presenting Cells↗
PubMed1995

Intermittent cyclical etidronate treatment maintains the mass, structure and the mechanical property of bone in ovariectomized rats.

We examined the mechanical properties of rat bones treated with etidronate intermittent cyclic treatment (etidronate-ICT). Fifty Fisher rats, 7 months of age, underwent ovariectomy (OVX; n = 40) or sham operation (n = 10). The OVX rats were assigned to 4 groups injected with etidronate at the respective dose of 0, 2, 4, or 8 mg/kg of body weight (bw) 5 days each week for 2 weeks, followed by a 10-week period of no treatment. This regimen was repeated for 48 weeks. At the end of the treatment period, the ultimate bending strength and structural stiffness of the femoral midshaft in the OVX-alone group were not reduced compared with the values of the sham group, while those in the etidronate-treated groups were significantly larger than the values of the OVX group. The compressive stiffness and strength of the vertebral bodies specimens prepared from L3 and L5 vertebrae were markedly decreased in the OVX group compared with those in the sham group, but the values in the etidronate-treated groups were maintained at the same levels as those in the sham group. Mechanical properties at the tissue level, such as elastic modulus and material strength of the femoral cortex, were increased in etidronate-treated groups compared with the OVX group. The flexural modulus was also increased. The compressive elastic modulus of vertebral body in treated groups was preserved at the same level as that in the sham group. These results clearly demonstrate that in ovariectomized rats long-term etidronate intermittent cyclic treatment preserves the mechanical properties both at the whole bone and the tissue level.

Absorptiometry, Photon↗
PubMed1995

Traumatic arteriovenous fistula treated by superselective embolisation with microcoils: case report.

A 27-year-old man with a traumatic direct dural arteriovenous fistula (DAVF) was treated using embolisation microcoils. He had suffered blunt trauma to the head while drunk and was aware of no neurological deficit. A few days after the accident, however, he noticed a bruit in the right temple. Angiography demonstrated a direct DAVF fed by the right middle meningeal artery and draining into a right temporal dural vein and the ipsilateral cavernous sinus. A Tracker-18 catheter was passed without difficulty through the fistula and the draining vein was then embolised from distal to proximal with microcoils, and finally the fistula was occluded with microcoils, resulting in total obliteration of the fistula. Immediately after the embolisation, the patient could no longer hear the bruit. Thus, when a microcatheter can be introduced into the draining vein, microcoils can be used as emboli in the treatment of direct DAVF.

Adult↗
PubMed1995

Percutaneous transluminal angioplasty for severe stenosis of the posterior cerebral artery: case report.

The Stealth dilation catheter was used for the intravascular treatment of a patient who had hemodynamically significant stenosis of the posterior cerebral artery and had a history of recurrent transient ischemic attacks associated with right hemiparesis and ipsilateral hemianopia dating from March 1993. Cerebral perfusion studies prior to and after the intravenous administration of acetazolamide demonstrated regions of moderately low perfusion and low hemodynamic reserve in the territories of the left middle and posterior cerebral arteries. Cerebral angiograms demonstrated severe stenosis of the left posterior cerebral artery and occlusions of both middle cerebral arteries, which had leptomeningeal anastomoses with the posterior cerebral arteries. Percutaneous transluminal angioplasty (PTA) was performed using the Stealth catheter on the stenotic segment of the left posterior cerebral artery after left superficial temporal artery-middle cerebral artery anastomosis. The patient manifested marked improvement in her neurologic condition just after PTA, in association with marked increase in cerebral perfusion and hemodynamic reserve in the territories of the left middle and posterior cerebral arteries. We have presented evidence that PTA can be used to treat patients with stenosis of the first segment of the posterior cerebral artery and hemodynamic compromise in the territory that artery supplies.

Aged↗
PubMed1995

Treatment of type II perimedullary arteriovenous fistulas by intraoperative transvenous embolization: case report.

BACKGROUND Perimedullary arteriovenous fistulas (AVFs) are abnormal vascular connections between medullary arteries and veins without an intervening nidus. It is thought to be difficult to treat Type II AVFs which have multiple feeding branches. We performed intraoperative transvenous embolization to treat Type II AVFs. CASE REPORT A 30-year-old man with Type II perimedullary arteriovenous fistulas (AVFs), present at the level of the L-1 vertebral body, underwent surgical and endovascular treatment. The patient displayed slight motor weakness (4/5) and slight hypesthesia in the right lower extremity. Angiograms demonstrated that an anterior spinal artery and posterior spinal arteries were feeding arteries for the perimedullary AVFs. The patient underwent surgical occlusion of the fistulas three times. Fistulas present on the dorsal surface of the spinal cord were occluded with hemoclips, while those located on the ventral and ventolateral aspect of the spinal cord were occluded transvenously with isobuthyl-2-cyanoacrylate (IBCA) during surgery. Total occlusion of the perimedullary AVFs was achieved with these procedures, and no change was noted postsurgically in the patient's symptoms. CONCLUSIONS In summary, Type II perimedullary AVFs are sometimes difficult to treat using either embolization or open surgery. In such cases, both open surgery and intraoperative transvenous embolization should be performed in order to obtain occlusion of multiple fistulas.

Adult↗
PubMed1995

Intraoperative electrophysiologic monitoring of cranial motor nerves in skull base surgery.

BACKGROUND: Intraoperative cranial nerve monitoring has been applied for the preservation of nerve function during skull base surgery. However, its usefulness is controversial because clinical results reported are limited. METHODS: We evaluated the usefulness of intraoperative electrophysiologic monitoring of the third to seventh cranial motor nerves in 15 patients undergoing skull base surgery. Intracranial bipolar electrical stimulation of each nerve was performed, and compound muscle action potentials (CMAP) were recorded from the innervated muscles. RESULTS: CMAPs were successfully recorded from 23 of the innervated muscles. The loss of the CMAP response during the manipulation of lesions or high stimulus intensity at the end of manipulation seem to be related to the postoperative deficits of nerve function. CONCLUSIONS: The results suggest that intraoperative electrophysiologic monitoring of cranial motor nerves is useful for prediction of postoperative nerve function.

Adult↗
PubMed1995

Cerebral revascularization using gracilis muscle transplantation for childhood moyamoya disease.

BACKGROUND: Omental transplantation is effective in the management of ischemia in the territories of the anterior and posterior cerebral arteries in childhood moyamoya disease. We introduced a surgical revascularization using gracilis muscle transplantation to these territories. METHODS: Between January 1991 and May 1993, six children with moyamoya disease, between the age of 3 and 13 years, underwent gracilis muscle transplantation to the territory of either the anterior or the posterior cerebral artery. The mean period of follow-up after surgery was 15.2 months, with a range of 5 to 32 months. Three of the six patients had suffered from frequent transient visual disturbance and were treated with unilateral or bilateral gracilis muscle transplantation to the territory of the posterior cerebral artery. The other three patients had suffered from frequent transient paraparesis, mental retardation, and/or rectal and urinary incontinence, and were treated with gracilis muscle transplantation bilaterally to the territories of the anterior cerebral arteries. RESULTS: All three patients with gracilis muscle transplantation unilaterally or bilaterally to the occipital lobes manifested complete disappearance of their symptoms. Two of the three patients with gracilis muscle transplantation bilaterally to the frontal lobes also manifested complete disappearance of their symptoms. The remaining patient who underwent the transplantation bilaterally to the frontal lobes, continued to have episodes of transient paraparesis, postsurgically, but the frequency of symptoms was markedly decreased. CONCLUSIONS: Ischemia in the territories of the anterior and/or posterior cerebral arteries could be overcome with the use of gracilis muscle transplantation in childhood moyamoya disease.

Adolescent↗
PubMed1995

Immune response to hepatitis C virus core protein in mice.

To analyse the immune response to the hepatitis C virus (HCV) core protein, we immunized mice with the protein. BALB/c (H-2d) and C3H/He (H-2k) mice were high responders, while C57BL/6 (H-2b) mice were low responders in terms of Th cell proliferative responses. All the strains showed comparable levels of antibody responses to the HCV core protein. The Th cell lines recognized residues 61-90 of the HCV core protein in the context of I-Ad (BALB/c) and residues 11-30 in the context of I-Ek (C3H/He), respectively. The Th cell lines were restricted by I-Ab in C57BL/6 mice but recognized no synthetic peptide that spanned the region, although derivative clones from the line recognized residues 1-20 and 91-110 of the HCV core protein, respectively. The Th cell lines were Th 1 subset in all three strains based on the profile of lymphokine secretion. The major B cell epitope of the protein was found to be within residues 21-40 of the HCV core protein in all three strains. These observations should be useful for better understanding of the immune response to the HCV core protein in vivo.

Amino Acid Sequence↗
PubMed1995

Haemodynamic evaluation of paraparetic transient ischaemic attacks in childhood moyamoya disease.

The haemodynamic mechanisms responsible for the appearance of paraparetic transient ischaemic attacks in ten patients with childhood moyamoya disease who subsequently underwent bifrontal omental transplantation were investigated. Cerebral perfusion (CP) was measured with 99mTc-hexamethylene-propyleneamine oxime single photon computed tomography prior to and after administration of acetazolamide. Cerebral perfusion was obtained by dividing radioisotope uptake per pixel in regions of interest by that in cerebellum. Haemodynamic reserve was defined as [CP after acetazolamide--CP before acetazolamide]/CP before acetazolamide x 100. Amounts of CP in the anterior portion of the frontal lobe and in the paracentral lobule were 0.70 +/- 0.04 and 0.74 +/- 0.03, respectively, before appearance of the transient ischaemic attacks. The latter was significantly higher than the former (p < 0.0001). Haemodynamic reserves were -11.1 +/- 2.8 and -9.6 +/- 3.0, respectively, at that time. These two parameters were significantly decreased just after paraparetic transient ischaemic attacks and two parameters in the paracentral lobule were more decreased than those in the anterior portion of the frontal lobe. But these increased again after bifrontal omental transplantation in these two regions. In summary, the watershed region was located anterior to the paracentral lobule before appearance of the transient ischaemic attacks, and widened and moved backward to include the paracentral lobule just before their appearance.

Cerebral Angiography↗
PubMed1995

Preoperative evaluation for risk of venous air embolism in the sitting position.

We report a patient with meningioma and radiological findings of erosive bony change, who developed venous air embolism via the diploic vein in the eroded inner table of the skull during craniotomy in the sitting position. The findings in our case suggest that preoperative radiological imaging evaluation can increase an awareness of the possibility of venous air embolism.

Aged↗
PubMed1995

Do recently developed techniques for skull base surgery increase the risk of difficult airway management? Assessment of pseudoankylosis of the mandible following surgical manipulation of the temporalis muscle.

We report our experience with anesthetic care for six patients with pseudoankylosis of the mandible following neurosurgical procedures, four of whom required fiberoptically guided intubation for anesthesia. We suggest that the development of operative approaches and reconstruction techniques in skull base surgery may increase the risk of difficult airway due to limitation of mouth opening.

Adult↗
PubMed1995

Conversion of amylase-secreting rat pancreatic AR42J cells to neuronlike cells by activin A.

When AR42J cells, an amylase-secreting pancreatic exocrine cell line, were treated with activin A, cells extended neuritelike processes, and, concomitantly, amylase-containing vesicles disappeared. Immunofluorescence and immunoelectron microscopy revealed that these processes had neurite-specific cytoskeletal architectures: neurofilaments and microtubule bundles with cross-bridges of microtubule-associated protein 2. In addition to such morphological changes, activin-treated cells exhibited a marked increase in cytoplasmic free calcium concentration in response to depolarizing concentration of potassium. Moreover, activin-treated AR42J cells expressed mRNA for alpha 1 subunit of the neuroendocrine/beta cell-type voltage-dependent calcium channel. In naive AR42J cells, a sulfonylurea compound, tolbutamide, did not affect free calcium concentration, while it induced a marked elevation of free calcium in activin-treated cells. Single channel recording of the membrane patch revealed the existence of ATP-sensitive potassium channel in activin-treated cells. These results indicate that activin A converts amylase-secreting AR42J cells to neuronlike cells. Given that pancreatic endocrine cells possess neuronlike properties and express ATP-sensitive potassium channel as well as neuroendocrine/beta cell-type voltage-dependent calcium channel, activin treatment of AR42J cells may provide an in vitro model system to study the conversion of pancreatic exocrine cells to endocrine cells in islets.

Activins↗
PubMed1995

[Pharmacological profile of F-0401, a novel dihydropyridine derivative. III. The anti-aggregatory action of F-0401 on rabbit platelets].

F-0401 is a newly synthesized dihydropyridine derivative with both antagonistic activity on platelet-activating factor (PAF) and inhibitory action on thromboxane A2(TXA2) synthetase activity. In the present study, we examined the effects of F-0401 on platelet aggregations in vitro and ex vivo in rabbits. F-0401 prevented PAF-, arachidonic acid (AA)- and collagen-induced platelet aggregations in vitro, but did not prevent the aggregation by ADP. The inhibitory effect of F-0401 on the aggregation by PAF (IC50 value: 3.4 x 10(-6) M) or by the threshold amount of AA (IC50 value: 4.3 x 10(-6) M) had the same potency as that of CV-3988 (a PAF antagonist) and ozagrel a (TXA2 synthetase inhibitor). Ex vivo studies also revealed that the anti-aggregatory effect occurred 1 h after the treatment of F-0401 (> 10 mg/kg, p.o.) and this effect had a tendency to last for 6 h. Nicardipine prevented the platelet aggregation only by PAF (IC50 value: 6.6 x 10(-5) M) in vitro. However, the preventive effect was not seen ex vivo. On the other hand, neither nifedipine nor flunarizine showed any effect on the stimulant-induced platelet aggregation in rabbits. These results suggest that F-0401 has anti-aggregatory action, which is attributable to both PAF antagonistic action and TXA2 synthetase inhibition in vitro and ex vivo.

Animals↗