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Biomedical subjects

I Sakaguchi

Publications and source records attributed to I Sakaguchi.

18 recordsLinked to original sources
PubMed2006

New intake control system based on river water quality.

The authors propose a new intake control system for water purification plants based on river water quality. In this system the intake flow rate of a plant will decrease while the river water is polluted, whereas it will increase after the water quality of the river has recovered. The purpose of this system is to reduce the operational costs of water purification while securing an adequate water supply. Simulation studies on the proposed system were conducted to investigate the reduced amount of coagulant dosage and waste sludge generated. Simulation results with 2-year, on-line turbidity data revealed that the reduction percentages of waste sludge for the first and second years were 5.8% and 8.5%, respectively. This remarkable effect suggests that the proposed system could also contribute to enlarging the capacity of landfill sites for incinerated sludge and to preserving the environment.

Computer Simulation↗
PubMed2003

Induction of cutaneous delayed hypersensitivity reactions in mice sensitized with intragastrically administered hapten: activation of Langerhans cells in the sensitization and elicitation phases.

BACKGROUND: As seen in atopic dermatitis, allergic diseases often produce lesions both in the gastrointestinal tract and the skin, suggesting the involvement of an immunological relationship between the two organs in the pathogenesis. OBJECTIVES: To study the role of gastric and epidermal Langerhans cells (LCs) in the sensitization and elicitation phases, respectively, of cutaneous delayed-type hypersensitivity (DTH) reactions to intragastrically administered hapten. METHODS: BALB/c mice, which were subjected to intragastric administration of trinitrochlorobenzene 5 days previously, received an elicitative challenge of the same hapten to the ear skin. Sections of the ear were immunostained for CD4 and CD8. Epidermal sheets of the ear and epithelial sheets of the forestomach were immunostained for I-A and observed under a confocal laser scanning microscope. RESULTS: Cutaneous DTH reactions were induced in mice, as demonstrated by an increase in ear thickness and a prominent infiltration of CD4+ and CD8+ lymphocytes at 24-36 h after the elicitative challenge. In the elicitation phase, epidermal LCs showed a significant increase in size, indicating in vivo activation, at 24 h. In the sensitization phase, gastric LCs increased in size at 2 h, became round at 6 h, and decreased in number at 24 h, possibly representing the sequential events of LC activation and migration from the epithelium. CONCLUSIONS: The present study demonstrated that gastric LCs and epidermal LCs were activated in vivo in the sensitization and elicitation phases, respectively, of cutaneous DTH reactions in orally sensitized mice.

Animals↗
PubMed2001

Structure-activity relationship of mycoloyl glycolipids derived from Rhodococcus sp. 4306.

Novel mycoloyl glycolipids with short carbon chains were isolated and purified from Rhodococcus sp. 4306, a soil origin of Actinomycetales. Their chemical structures were identified as trehalose 6,6'-dimycolate (TDM), trehalose 6-monomycolate, glucose 6-monomycolate, mannose 6-monomycolate and fructose 6-monomycolate. The length of carbon chains and number of double bonds of mycolic acids were C(34), C(36)and C(38)saturated, monoenoic and dienoic molecular species, which were much shorter than those of Mycobacterium tuberculosis (C(78-88)monoenoic and dienoic). Among them, only TDM could induce prominent granulomatous inflammation of the lung and spleen in mice. By contrast, other mycoloyl glycolipids induced mild lesions. The small-sized TDM of Rhodococcus possessed granulomatogenic activity, however, the toxicity was much lower than that of M. tuberculosis. Rhodococcal TDM was composed of mycolic acid with the shortest carbon chains, when compared to granulomatogenic TDM of Mycobacterium, Nocardia and Rhodococcus reported previously. Our results imply that rhodococcal TDM is a pathogenetic factor similar to that of M. tuberculosis, although rhodococcal TDM exhibits low toxicity.

Actinomycetales Infections↗
PubMed2001

Granulomatous tissue formation of shikon and shikonin by air pouch method.

"The extract of shikon" (SK) and shikonin play important roles in the development of granulomatous tissue formation. To reveal the augmenting effect of SK or shikonin on vascular endothelial growth factor (VEGF) production and neovascularization, we investigated murine granulomatous tissue induced by SK and shikonin, comparing them to pouches in which trehalose 6,6'-dimycolate (TDM) was injected. The development of granulomatous tissue formation was evaluated by the wet weight of pouch walls. At day 5 and 7 after SK and shikonin injection, prominent granulomatous tissue formation was detected. Histological observations on the development of granulomatous tissue showed that the pouch was formed in the submuscular connective tissue and necrotic tissue directly facing the cavity and granulomatous tissue developed in the connective tissue. At day 1, VEGF-positive neutrophils accumulated in the pouch wall. Granulomatous tissue formation and neovascularization by injection of SK or shikonin was not more prominent than TDM. However, the present results indicate that SK and shikonin induce neovascularization in granulomatous tissue.

Animals↗
PubMed2000

Expression of vascular endothelial growth factor by granulated metrial gland cells in pregnant murine uteri.

Granulated metrial gland (GMG) cells are a characteristic uterine component belonging to a natural killer cell lineage. This study is aimed at revealing their kinetic and spatial relationship with vascular growth during pregnancy and the expression of vascular endothelial growth factor (VEGF). GMG cells and blood vessels were identified by periodic-acid-Schiff-reagent (PAS)-stained granules and positive staining for factor-VIII-related antigen, respectively. GMG cells were widely distributed in the decidua and metrial gland and showed a numerical increase with a peak at day 13 in parallel with the increase of vascular density. Preceding the maximal vascular development at day 13, microvessels with a narrow lumen representative of neovascularization prevailed at days 7-9, and the VEGF content in the decidua/metrial gland was significantly elevated at days 7-13 concurrently with mRNA expression. By immunolight microscopy combined with PAS staining, GMG cells with PAS-stained granules were positive for VEGF. Immunoelectron microscopy demonstrated that immunoreactions were diffuse in the cytoplasm but not localized in the granules. In contrast, fibroblast-like stromal cells were negative. These data indicate that GMG cells express VEGF and may play inducing roles in uterine neovascularization during pregnancy.

Animals↗
PubMed2000

Trehalose 6,6'-dimycolate (Cord factor) enhances neovascularization through vascular endothelial growth factor production by neutrophils and macrophages.

Trehalose 6,6'-dimycolate (TDM) plays important roles in the development of granulomatous inflammation during infection with Mycobacterium spp., Rhodococcus spp., etc. To reveal the augmenting effect of TDM on vascular endothelial growth factor (VEGF) production and neovascularization, we investigated murine granulomatous tissue air pouches induced by Rhodococcus sp. strain 4306 TDM dissolved in Freund's incomplete adjuvant (FIA), comparing them to pouches treated with FIA alone. Histologically, granulomatous tissue and new vessel formation, which reached a maximum at day 7, was greatly enhanced by treatment with TDM. At day 1, VEGF-positive neutrophils accumulated in the pouch wall with frequency of 95% of total infiltrating cells, adhering to TDM-containing micelles. By day 3, granulomatous tissue and new vessels started to develop, and VEGF-positive macrophages appeared in a small number and gradually increased in number thereafter. The pouch contents of VEGF, interleukin-1beta, tumor necrosis factor alpha, and transforming growth factor beta were significantly elevated in TDM-treated pouches, with peaks at days 1, 0.5, 1, and 3, respectively, compared to those of control pouches, while that of basic fibroblast growth factor showed no significant increase. Treatment with anti-VEGF antibody inhibited TDM-induced granulomatous tissue formation and neovascularization, and administration of recombinant VEGF into pouches treated with FIA alone induced neovascularization comparable to that in the TDM-treated pouches. Incubation of neutrophils and macrophages on TDM-coated plastic dishes increased the VEGF release. The present results indicate that TDM augments VEGF production by neutrophils and macrophages and induces neovascularization in the granulomatous tissue.

Animals↗
PubMed1999

The posterior temporal artery as the recipient in superficial temporal artery to posterior cerebral artery bypass. Technical note.

BACKGROUND: While superficial temporal artery (STA) to superior cerebellar artery (SCA) or STA to posterior cerebral artery (PCA) anastomosis has been used for rostral brain stem ischemia, it is reported not infrequently to be associated with serious complications. Although the inferior temporal artery has been proposed as a possible recipient artery for the STA, its advantage is not yet widely recognized. CASE REPORT: A 42-year-old man presented with repeated loss of vision in the left visual field. Angiography disclosed occlusion in the proximal portion of the P2 segment of the right PCA. The second case was a 68-year-old man experiencing swallowing disturbance; the bilateral vertebral arteries were markedly stenotic. Since hemodynamic insufficiency was considered to be responsible for the patients' symptoms, STA-PCA anastomosis was performed using the posterior temporal artery (PTA) as the recipient. The postoperative courses were uneventful with good patency of the bypass. TECHNIQUE: Through a horizontally extended temporal craniotomy with the base of the temporal bone sufficiently drilled away, the inferior aspect of the temporal lobe was searched for a recipient artery for the STA. The anastomosis was performed with less difficulty and at a shallower level, by 20 mm in one case and by 10 mm in the other, than had we anastomosed it to the P2 segment of the PCA. CONCLUSION: Anastomosis of the STA to the PTA is less complicated than anastomosis of the STA to the main branch of the PCA for the treatment of rostral brain stem ischemia.

Adult↗
PubMed1998

Structure-function studies of human leptin.

To elucidate the structural requirement of human leptin for its functions, the wild-type, mutant-type, C-terminal deletion, and N-terminal deletion were expressed in Escherichia coli and purified in soluble forms. These leptin analogs were intracerebroventrically injected into C57BL/6J ob/ob mice, and their in vivo biological activities were evaluated. The mutant-type leptin lacking a C-terminal disulfide bond reduced food intake at doses of more than 15 pmol/mouse, which was as effective as the wild-type leptin. C-terminal deletion without the loop structure, also significantly, but to a lesser extent, reduced food intake at doses of more than 90 pmol/mouse. However, N-terminal deletions showed no effect on food intake. We also evaluated the effects of the leptin analogs on radiolabeled leptin binding to its receptor in the choroid plexus using autoradiography. An excess of unlabeled mutant-type leptin as well as wild-type leptin led to complete inhibition of binding. C-terminal deletions led to weak inhibitory activity, whereas N-terminal deletions caused no inhibitory activity. These results clearly demonstrate that the N-terminal region of leptin is essential for both its biological and receptor binding activities. The amino acid sequence of the C-terminal loop structure is also important for enhancing these actions, whereas the C-terminal disulfide bond is not needed.

Animals↗
PubMed1998

Study of the accelerating effect of shikonin and alkannin on the proliferation of granulation tissue in rats.

The present study was carried out to compare the accelerating effect of shikonin and alkannin and to elucidate the expression of CD antigen and histological changes on the proliferation of granulation tissue in rats. Shikonin and alkannin produced a dose-dependent acceleration of the cotton pellet-induced granuloma formation and this accelerating potency of both compounds on the proliferation of granulation tissue was about the same 5 and 10 d after implantation of the cotton pellet. Also, both compounds increased the ratio of CD11b+ cells in the granulation tissue 5 and 10 d after implantation of the cotton pellet. Both compounds increased the expression of CD11b+ cells with granulocytes such as macrophages and histiocytes, and then accelerated the proliferation of fibroblasts and collagen fiber. On the other hand, neither compound increased the ratio of CD3+ cells in the granulation tissue after 5 and 10 d. These results suggest that shikonin and alkannin accelerate the proliferation of granulation tissue induced by the cotton pellet and this accelerating effect may be attributed to an increase in the expression of CD11b+ cells, and the acceleration of the proliferation of fibroblasts and collagen fiber in the granulation tissue.

Animals↗
PubMed1996

Impairment of hippocampal mossy fiber LTD in mice lacking mGluR2.

Subtype 2 of the metabotropic glutamate receptor (mGluR2) is expressed in the presynaptic elements of hippocampal mossy fiber-CA3 synapses. Knockout mice deficient in mGluR2 showed no histological changes and no alterations in basal synaptic transmission, paired-pulse facilitation, or tetanus-induced long-term potentiation (LTP) at the mossy fiber-CA3 synapses. Long-term depression (LTD) induced by low-frequency stimulation, however, was almost fully abolished. The mutant mice performed normally in water maze learning tasks. Thus, the presynaptic mGluR2 is essential for inducing LTD at the mossy fiber-CA3 synapses, but this hippocampal LTD does not seem to be required for spatial learning.

Animals↗
PubMed1996

Selective hypothermic perfusion of canine brain.

A method for selective brain cooling by profound hemodilution with cold Ringer's lactate solution was previously reported in 1992. We recently modified this technique by combining it with an ultrafiltration and rewarming circuit between the left jugular vein and the inferior vena cava. We used 12 beagle dogs to study the efficacy of selective cerebral hypothermia induced by this modified technique. The brain temperature decreased to 28 degrees C within 5.4 +/- 2.7 minutes and to 20 degrees C within 15.5 +/- 9.4 minutes. The lowest brain and rectal temperatures were 17.0 +/- 1.8 degrees C and 32.1 +/- 2.2 degrees C, respectively. All animals survived in good condition without evidence of neurological deficits until they were killed at 10 weeks. Histological examination of the brains with 2,3,5-triphenyltetrazolim chloride demonstrated no evidence of ischemic lesions, and even in the hippocampus, there was no evidence of ischemic neuronal damage.

Animals↗
PubMed1994

Pharmacological studies on a new dihydrothienopyridine calcium antagonist, S-312-d. 5th communication: anticonvulsant effects in mice.

S-312, S-312-d, but not S-312-l, L-type calcium channel antagonists, showed anticonvulsant effects on the audiogenic tonic convulsions in DBA/2 mice; and their ED50 values were 18.4 (12.8-27.1) mg/kg, p.o. and 15.0 (10.2-23.7) mg/kg, p.o., respectively, while that of flunarizine was 34.0 (26.0-44.8) mg/kg, p.o. Although moderate anticonvulsant effects of S-312-d in higher doses were observed against the clonic convulsions induced by pentylenetetrazole (85 mg/kg, s.c.) or bemegride (40 mg/kg, s.c.), no effects were observed in convulsions induced by N-methyl-D-aspartate, picrotoxin, or electroshock in Slc:ddY mice. S-312-d may be useful in the therapy of certain types of human epilepsy.

Administration, Oral↗
PubMed1992

Selective cooling of brain using profound hemodilution in dogs.

A new method of selective cooling of the brain was studied under profound hemodilution in 17 dogs. The carotid and vertebral arteries were bilaterally exposed, and the right vertebral artery was destroyed to provide an infusion route for cold solution for brain cooling. After the other three cerebral arteries were clamped simultaneously in the neck under low-dose heparinization, cold Ringer's lactate solution was immediately perfused into the right vertebral artery. Brain temperatures fell gradually in two dogs, and the experiments were terminated. In 10 dogs, the brain temperature fell to 28 degrees C within 4.4 +/- 1.5 minutes and was maintained at 27.0 +/- 1.0 degrees C for 60 minutes. During this interval, the body temperature was 33.9 +/- 1.6 degrees C, the stump pressure of the vertebral artery was 58 +/- 15 mm Hg, and the hematocrit value of cerebral venous blood was 7.2 +/- 4.2%. Inspection of the brain during infusion revealed paleness of the cortical vessels and no evidence of swelling. All animals survived in good condition until the time of death at 10 weeks. Histological examination of the brain revealed no evidence of ischemic injury. In a control study of five dogs, Ringer's solution at 38 degrees C was infused in the same manner as the cold solution. None of these dogs recovered from anesthesia. It is concluded that selective cooling of the brain under profound hemodilution has a protective effect on cerebral ischemia and provides a relatively bloodless operative field.

Animals↗
PubMed1992

[Carotid stenosis complicated by coronary disease; a case report].

A 66-year-old-man with carotid stenosis complicated by coronary disease is reported. He suffered from mild motor weakness on the right side and speech disturbance. Radiological examination revealed 90% stenosis at the cervical portion of the left internal carotid artery, and two-vessel coronary disease. In order to prevent intraoperative cardiac stroke, initial percutaneous coronary angioplasty (PTCA), was performed and the subsequent carotid endarterectomy (CEA) was performed successfully. Preoperative symptoms gradually improved and he was discharged as ambulatory. Because atherosclerosis is always systemic, patients with carotid artery disease should be examined for coronary disease. We recommend greater use of coronary angiography and, when a lesion is found, the use of PTCA, which is a safer method in terms of preventing intraoperative cardiac stroke of CEA than any other method.

Aged↗
PubMed1978

Adrenal hypertrophy produced by 17alpha-esterified glucocorticoids in rat foetus.

Glucocorticoids were injected sc into rat foetuses through the uterine wall on day 19 of intrauterine development; two days later the foetuses were removed and their adrenal glands were weighed. Some betamethasone derivatives produced marked adrenal hypertrophy in the foetuses. Structural characteristics of the effective compounds were 17alpha-esterification and 16beta-methylation. 9alpha-Halogenation and 21-esterification of glucocorticoids were not essential for producing the hypertrophy. Propionic acid at the C-17 position was more effective than valeric and acetic acids in producing the hypertrophy. The effect of betamethasone 17, 21-dipropionate was dose-responsive and prevented by simultaneous administration of betamethasone 21-disodium phosphate. Results obtained with decapitated or encephalectomized foetuses suggested that the hypertrophy produced was not due to a direct action of the glucocorticoids on the adrenal gland, but mediated by the hypothalamo-pituitary system.

Adrenal Gland Diseases↗