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T Sakurai

Publications and source records attributed to T Sakurai.

At least 271 records · Page 15Linked to original sources
PubMed1997

Induction of neurite outgrowth through contactin and Nr-CAM by extracellular regions of glial receptor tyrosine phosphatase beta.

Receptor protein tyrosine phosphatase beta (RPTPbeta) is expressed as soluble and receptor forms with common extracellular regions consisting of a carbonic anhydrase domain (C), a fibronectin type III repeat (F), and a unique region called S. We showed previously that a recombinant Fc fusion protein with the C domain (beta C) binds to contactin and supports neuronal adhesion and neurite growth. As a substrate, betaCFS was less effective in supporting cell adhesion, but it was a more effective promoter of neurite outgrowth than betaCF. betaS had no effect by itself, but it potentiated neurite growth when mixed with betaCF. Neurite outgrowth induced by betaCFS was inhibited by antibodies against Nr-CAM and contactin, and these cell adhesion molecules formed a complex that bound betaCFS. NIH-3T3 cells transfected to express betaCFS on their surfaces induced neuronal differentiation in culture. These results suggest that binding of glial RPTPbeta to the contactin/Nr-CAM complex is important for neurite growth and neuronal differentiation.

Animals↗
PubMed1997

Effects of hypotonic stress on the survival of mouse oocytes and embryos at various stages.

To examine the sensitivity of mammalian oocytes and embryos to osmotic swelling, which can occur during the removal of cryoprotectant from cryopreserved cells, the effect of hypotonic stress on the survival of fresh and vitrified mouse oocytes/embryos at various stages was examined. Oocytes and embryos were suspended in phosphate-buffered saline (PBS) media of various hypotonicities for 30 min at 25 degrees C. They were then returned to isotonic PBS medium, and the survival was assessed by the apparent integrity of the blastomeres and/or the developmental potential during culture. The survival of stressed embryos at one- to eight-cell stages assessed by the appearance was close to that assessed by the developmental ability, suggesting that hypotonic stress causes physical damage in the cell membrane. Fresh oocytes and embryos were almost totally unaffected by exposure to a 0.5x isotonic solution at all developmental stages examined. However, the extent of injury resulting from exposure to 0.3 to 0.2x isotonic solutions varied and depended on the developmental stage of the embryos. For example, zygotes were the least sensitive and morulae were the most sensitive to the hypotonic stresses. Except for morulae, vitrified cells were more sensitive to hypotonic stresses than were fresh ones. However, in many cases, the sensitivity was reduced or eliminated when the oocytes and embryos were cultured for a short period before exposure to the hypotonic stress. Furthermore, the survival rate of some stressed embryos which had been equilibrated in vitrification solution without cooling was higher than the survival of embryos stressed immediately following vitrification. These results show that sensitivity to osmotic swelling is variable among oocytes and embryos. The results also show that cryopreserved cells just after warming are more sensitive to osmotic swelling than are fresh ones, and even swelling corresponding to that in 0.5x solution may decrease survival in some stages.

Animals↗
PubMed1997

Antimetastatic effect of recombinant human macrophage-colony-stimulating factor against lung and liver metastatic B16 melanoma.

We studied the effect of recombinant human macrophage-colony-stimulating factor (rhM-CSF) on the formation of lung and liver metastases following the i.v. injection of the B16 melanoma subline (B16 LiLu) into mice. When rhM-CSF was administered before the B16 inoculation, the number of tumor metastases decreased in the lung and liver. However, the administration of rhM-CSF after B16 inoculation did not produce an antimetastatic effect in the lung, but did in the liver, B16 cells labeled with 5-[125I]-iodo-2'-deoxyuridine (125I-dUrd) were injected and the arrest of tumor cell emboli was examined in the capillary beds of the lung and liver of mice treated with either vehicle or rhM-CSF. In both groups, there were the same numbers of B16 cells in both the lung and the liver 3 minutes after the B16 injection, and almost all tumor cells died within 24 h. However, the number of cells surviving in the lung was decreased in mice injected with rhM-CSF (37%). There was no difference in the number of cells in the livers of mice treated either with vehicle or rhM-CSF in the first 24 h after tumor cell injection. The administration of rhM-CSF increased NK 1.1+ cells in the mouse spleen and facilitated NK activity in vivo. At the same time, the administration of an anti-NK 1.1 antibody blocked the antimetastatic effect of rhM-CSF in the lung but not in the liver. The antibody was effective only when it was injected before the B16 inoculation. These results suggest that the antimetastatic effect of rhM-CSF in the lung was mediated by NK 1.1+ cells within 24 h of B16 injection. In contrast, the antimetastatic effect of rhM-CSF in the liver was mediated not only by NK 1.1+ cells but also by other antimetastatic systems such as macrophages.

Animals↗
PubMed1997

Apical tubular network in the rat kidney proximal tubule cells studied by thick-section and scanning electron microscopy.

The apical cytoplasm of several absorbing epithelia contains well-developed apical tubules (AT) which contribute to membrane recycling from endocytic vacuoles to the apical cell membrane. In this study, we examined three-dimensional structures of the AT in rat kidney proximal tubule cells by transmission and scanning electron microscopy. In thin sections, the AT appeared as straight tubules with a rather constant diameter (70-90 nm), but others were curved and, occasionally, branching. No AT were labeled with the marker for the external cell surface (ruthenium red) or exhibited histochemical enzyme activity for lysosomal hydrolase (acid phosphatase). After intravenous injection of horseradish peroxidase, it was absorbed in the kidney proximal tubule cells and the AT were labeled with HRP reaction products. Stereo-viewing of the labeled AT in thick sections revealed that they formed an interconnected tubular network. Scanning electron microscopy allowed a three-dimensional view of the AT, in which a network of branching and anastomosing tubules was revealed. These observations indicate that the AT are intracellular endosomal compartments which form an extensive tubular network in the apical cytoplasm. The possibility that this apical tubular network serves as a large membrane store for membrane recycling is discussed.

Acid Phosphatase↗
PubMed1997

Cellular mechanisms underlying cognition-enhancing actions of nefiracetam (DM-9384).

We have studied cellular mechanisms underlying cognition-enhancing actions of nefiracetam (DM-9384), a newly developed cognitive enhancer, by biochemical experiments on cholinergic and GABAergic transmissions as well as electrophysiological experiments on neuronal Ca2+ channels. In behavioral experiments in rats, nefiracetam (3 mg/kg) ameliorated amnesia induced by basal forebrain (BF) lesion or treatment of scopolamine. Biochemical experiments revealed that nefiracetam increased uptake and release of transmitters in both cholinergic and GABAergic systems in rat brain. In electrophysiological studies, nefiracetam (1 microM) increased long-lasting (N/L-type) Ca2+ channel currents in NG108-15 cells. The nefiracetam action on Ca2+ channels was blocked by pertussis toxin (PTX). The results suggest that nefiracetam improves impaired memory by facilitating cholinergic and GABAergic transmissions in the brain. It is further suggested that PTX-sensitive G-proteins and Ca2+ channels associated with these G-proteins are responsible for the action of nefiracetam on neurotransmission.

Animals↗
PubMed1997

Acute 3-nitropropionic acid intoxication induces striatal astrocytic cell death and dysfunction of the blood-brain barrier: involvement of dopamine toxicity.

Mechanisms underlying the selective vulnerability of the lateral striatal area to the toxic effects of 3-nitropropionic acid (3-NPA) were investigated in rats. A single exposure to 3-NPA (20 mg/kg, s.c.) induced no deficits in behavior and histology, but subsequent injection produced motor symptoms, catalepsy, lip smacking, abnormal gait, paddling, rolling, opisthotonos, tremor, recombence, somnolence and so on, in 30% of the animals within a few hours. Diffusion-weighted magnetic resonance imaging of the brains revealed an area of high signal intensity in the bilateral striata. By this stage (within a few hours), striatal astrocytes had become swollen and disintegrated. Extravasation of immunoglobulin G was detected, indicating blood-brain barrier (BBB) dysfunction. Electron microscopy revealed edema and disorganization of structures inside the astrocytic end-feet around the branches of the lateral striatal artery. Neurons were less vulnerable than astrocytes to the 3-NPA injury. Treatment of the rats with D2 receptor agonist prior to exposure to 3-NPA attenuated the behavioral abnormalities and histological damage whereas pretreatment with D2 antagonist exacerbated these changes. The concentrations of extracellular dopamine (DA) and dihydroxyphenyl acetic acid (DOPAC) were both increased in rats exposed to 3-NPA. In vitro imaging of astrocytes revealed a progressive increase in [Ca2+]i after superfusion with 3-NPA, and the 'ceiling' level was maintained even after extensive washing. DA superfusion also increased the astrocytic [Ca2+]i and this increase was reversible. Data indicate that 3-NPA-induced striatal damage was associated with astrocytic cell death and dysfunction of the BBB. Intracellular edema and extreme Ca2+ overload induced by the toxin were further aggravated by an increase in the level of DA activity. These factors acting either singly or in combination may trigger astrocyte destruction.

Animals↗
PubMed1997

Effect of prednisolone on IgE-dependent biphasic cutaneous reaction in BALB/c mice.

1. The effect of prednisolone on IgE-dependent, antigen-induced biphasic cutaneous reaction in BALB/c mice was investigated. 2. The biphasic cutaneous reaction with peak responses at 1 h and 24 h after antigen stimulation was suppressed by prednisolone administered 2 h before the challenge. 3. Although antigen challenge increased the expression of IL-1 beta and TNF-alpha mRNA in the mouse ear, prednisolone did not affect the increase. 4. Anti-IL-1 beta antibodies inhibited the later phase of biphasic cutaneous reaction, whereas anti-TNF-alpha antibodies inhibited both phases of the reaction. 5. Prednisolone inhibited edematous reactions caused by both IL-1 beta and TNF-alpha. 6. Proinflammatory cytokines, such as IL-1 beta and TNF-alpha, participate in the development of the biphasic cutaneous reaction, especially in its later phase, in mice, and prednisolone inhibits the reaction by suppressing the action of cytokines, at least in part.

Animals↗
PubMed1997

Measurement of spinal cord blood flow by an inhalation method and intraarterial injection of hydrogen gas.

PURPOSE: This study was performed to determine spinal cord blood flow using the H2 clearance method. METHODS: In 12 dogs we measured blood flow determined by hydrogen clearance techniques (BF) in both gray and white matter by spinal cord puncture, and compared the results with BF measured by a catheter inserted intrathecally to avoid spinal cord injury. We studied direct intraarterial and intravenous injection of hydrogen in addition to the inhalation method because hydrogen is an explosive gas. RESULTS: BF measured intrathecally with catheters adherent to either the ventral or the dorsal funiculus did not differ significantly from that of the gray matter. BF measured with a catheter inserted into the epidural space was about one fourth of the BF measured intrathecally. Values measured by the intraarterial injection method did not differ significantly from those obtained by the inhalation method. CONCLUSIONS: BF measured with a catheter inserted intrathecally reflects blood flow in the gray matter of the spinal cord. Using intraarterial injection of H2, BF was safety and accurately measured while avoiding the risk of explosion.

Administration, Inhalation↗
PubMed1997

Hemodynamic assessment of femoropopliteal venous reflux in patients with primary varicose veins.

PURPOSE: The aim of this study was to assess the anatomic distribution and extent of deep venous reflux in patients with primary varicose veins (PVVs) and to investigate its influence on venous hemodynamics. METHODS: Femoropopliteal venous reflux was examined using duplex color Doppler ultrasonography in 356 limbs with PVVs in 240 patients. Photoplethysmography (PPG) was performed using above-knee and below-knee tourniquets to determine the contributions of deep and superficial venous insufficiency. RESULTS: Of 356 limbs with PVVs, 61 (17.1%) had femoropopliteal venous reflux, 42 (11.8%) had superficial femoral venous reflux alone, and 57 (16.0%) had popliteal venous reflux alone. Femoropopliteal venous reflux was associated significantly with clinical symptoms and shortened the half venous refilling time measured by PPG, especially in the presence of incompetent perforating veins. These findings were obtained regardless of the presence of long saphenous vein reflux. CONCLUSIONS: Femoropopliteal venous reflux associated with PVVs plays an important role in the pathophysiologic mechanism of venous stasis and influences venous hemodynamics in the presence of incompetent perforating veins and short saphenous vein.

Adolescent↗
PubMed1997

Treatment for abdominal aortic aneurysm in a patient with hemophilia A: a case report and review of the literature.

A 77-year-old man with abdominal aortic aneurysm (AAA) was referred to our department. His AAA, which was 6 cm in diameter, was found incidentally with ultrasonography. On admission the diagnosis of hemophilia A was made for the first time in his life because activated partial thromboplastin time was decreased to 32.3% and factor VIII coagulant activity was 2.1% (normal range 40% to 140%). Recombinant factor VIII supplemental therapy was continued during surgery to maintain his factor VIII level within the normal range. His AAA was operated successfully with bifurcated graft replacement. No unusual bleeding complications occurred during his hospitalization. With proper preparation the patient with AAA and hemophilia A can safely undergo surgical treatment. Three other cases of AAA with hemophilia in the English literature were reviewed, and this is the oldest patient with hemophilia who underwent AAA surgery.

Aged↗
PubMed1997

Effect of walking distance on the change in ankle-brachial pressure index in patients with intermittent claudication.

OBJECTIVES: The ankle-brachial pressure index (ABPI) responses to different exercise intensities on a treadmill were evaluated to clarify the relationship between intermittent claudication and the haemodynamics in the leg. PATIENTS AND METHODS: Thirty patients with intermittent claudication (32 symptomatic legs) due to peripheral arterial occlusive disease were exercised on a treadmill to determine their pain-free walking distance, maximum walking distance (MWD) and recovery time. Each subject was exercised at 25% and 50% of the MWD to determine the effect of work intensity on the drop in ABPI, and the recovery time. RESULTS: In the claudicating legs, 25% of the MWD resulted in almost the same reduction in ABPI as 50% of the MWD, and the MWD. In contrast, the ABPI in the asymptomatic legs (13) was significantly decreased in proportion to the walking distance. The recovery time increased linearly in both the groups, as the walking distance increased. CONCLUSION: The recovery time of the ABPI correlated well with the intensity of workload, while the drop in ABPI did not.

Aged↗
PubMed1997

Long-term outcome of endoscopic balloon dilation in obstructive gastroduodenal Crohn's disease.

BACKGROUND AND STUDY AIMS: Although balloon dilation is widely used in nonmalignant pyloric stenosis, little information is available on either the short-term or long-term results of this type of therapy in patients with obstructive gastroduodenal Crohn's disease. PATIENTS AND METHODS: Five patients with Crohn's disease who had obstructive gastroduodenal lesions were treated using endoscopic balloon dilation. RESULTS: All the initial dilations successfully provided symptomatic relief. However, three of the five patients developed recurrent obstructive symptoms during a mean follow-up period of 4.2 years. Due to symptomatic recurrence, three patients required successive or regularly scheduled repeat balloon dilations, which were successful without any complications, and all of the patients were able to avoid surgical intervention. CONCLUSIONS: These results suggest that over a prolonged period of time, patients who have undergone balloon dilation for obstructive gastroduodenal Crohn's disease have a high rate of recurrence of symptomatic gastric obstruction. However, repeat dilations are successful in continuing to prevent the need for surgery.

Adult↗
PubMed1997

Identification and characterization of functional residues in a Na+/H+ antiporter (NhaA) from Escherichia coli by random mutagenesis.

Forty-one mutants were isolated by means of random PCR mutagenesis of the Escherichia coli Na+/H+ antiporter (nhaA), which could not support the growth of a nhaAnhaB mutant (HIT delta AB-) on plates containing 0.15 M LiCl (pH 7.5) or 0.65 M NaCl (pH 8.0). Most of the mutants were sensitive to both NaCl and LiCl, or to LiCl alone. DNA sequencing revealed that twelve of the mutants had single amino acid substitutions. All the mutations, except for H225P, were of the conserved residues of NhaA homologues and located in the putative transmembrane helices. The Na+/H+ and Li+/H+ antiporter activities of the mutant NhaA were measured with everted membrane vesicles: eight of the mutants lost both antiporter activities completely under all pH conditions examined. Although both D133A and L138P retained low Li+/H+ antiporter activity, D133A lost Na+/H+ antiporter activity, while L138P retained normal Na+/H+ antiporter activity at pH 7.0 and 8.0. Interestingly, at pH 8.5, L138P no longer showed any Li+/H+ antiporter activity. H225P retained relatively high antiporter activities, although their pH dependence was altered. These observations supported the previous indication that His-225 is part of the pH sensor [Gerchman, Y. et al. (1993) Proc. Natl. Acad. Sci. USA 90, 1212-1216]. L73R exhibited about 20% each of the activities only at pH 8.0, and showed a similar pH dependence to H225P in both Na+/H+ and Li+/H+ antiport. Therefore, in addition to His-225, Leu-73, and/or its vicinity may also contribute to the pH sensing.

Amino Acid Sequence↗
PubMed1997

Treatment of squamous cell carcinoma of the esophagus with alternating radiotherapy and chemotherapy (cisplatin, methotrexate, and peplomycin).

Between 1985 and 1990, 20 patients with stage 2 and 3 esophageal cancer without esophagopulmonary fistulas were treated with alternating radiotherapy and chemotherapy (cisplatin, methotrexate, and peplomycin). Patients given the combined therapy received courses of chemotherapy during weeks 1 and 6 and radiotherapy during weeks 2-5 and 7-9. Chemotherapy consisted of i.v. cisplatin (80 mg/ m2 of body surface area) on day 1, i.v. methotrexate (40 mg/ m2) on day 2, and s.c. peplomycin (10 mg/day) continuously from day 2 to day 5. Radiotherapy was external irradiation with or without intracavitary irradiation. In seven cases, external irradiation alone was administered at 65-70 Gy, and in 13 cases, external irradiation (50-55 Gy) was combined with intracavitary irradiation (14-20 Gy). At the end of treatment, the rate of complete response was 60% with an overall response rate of 95%. Five-year total survival was 25%; cause-specific survival was 36.8%. The most common acute toxicities were bone marrow suppression, hepatic and renal damage, pneumonitis, and esophagitis. There was no life-threatening toxicity.

Aged↗
PubMed1997

A case of systemic malignant lymphoma with intestinal involvement of lymphomatous polyposis type.

Multiple lymphomatous polyposis is a rare type of intestinal lymphoma characterized by non-Hodgkin's lymphoma of follicular mantle cell origin and extremely poor prognosis. We report a case of systemic lymphoma with the intestinal involvement of multiple lymphomatous polyposis. Although radiographic and endoscopic features of the case were compatible with multiple lymphomatous polyposis, histologic evidence suggested the diagnosis of diffuse large cell lymphoma rather than mantle cell lymphoma. Our case seems to be unique in its histologic findings and also in its prognosis, because the patient has been alive for more than 50 months after diagnosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Intramural sarcoma of the carotid artery with adventitial inflammation and fibrosis resembling 'inflammatory aneurysm'.

A rare case is described of an intramural sarcoma of the right common carotid artery coexisting with adventitial inflammation and fibrosis, resembling 'inflammatory aneurysm', which was resected from a 33-year-old Japanese woman who had presented with a pulsatile mass on the right side of the anterior neck. Grossly, the wall of the carotid artery showed an intimal tear with dissection of the media filled with thrombus. A grayish area, abutting directly onto the dissected space and involving the media and inner adventitia, was composed of alpha-smooth muscle actin-positive and desmin-negative polygonal and spindle cells with large blunt-ended nuclei and coarse granular chromatin arranged into a well-organized interlacing bundle pattern. This portion was thus considered to represent leiomyosarcoma. White to yellow-tan fibrotic tissue present in the adventitial area consisted of extensive lamellar fibrosis with scattered foci of lymphoplasmacytic aggregates and obliterated arteries, and lacked atypical spindle and polygonal cells. These changes accorded with the histopathological findings hitherto described in cases of 'inflammatory aneurysm', which is known to almost exclusively involve the abdominal aorta. We consider this case unique in that the leiomyosarcoma involved an artery other than the aorta, with an 'inflammatory aneurysm'-like reaction in the same site. The possible relationship between these two conditions is discussed.

Adult↗
PubMed1997

A simple technique for identifying the adrenal glands at necropsy.

There is no detailed and practical description of how to identify the adrenal glands at necropsy. A simple technique is described, based on anatomical location. After removing the aorta by the Rokitansky method, the inferior vena cava is opened. The orifice of the right adrenal vein is identified just above the right renal vein, and a probe is inserted into it as a marker. The right adrenal gland is identified at the centre above the line of the probe after separation of the diaphragm, which is attached to the liver. The left adrenal vein arises as the first bifurcation of the left renal vein after its origin from the inferior vena cava. A probe is inserted into it and the vein is opened along the probe. The left adrenal gland is identified at the left side of the left adrenal vein, embedded in fat. This method is also useful in cases with severe adhesion, fibrosis, or metastases.

Adrenal Glands↗