Biomedical subjects

N Yoshida

Publications and source records attributed to N Yoshida.

At least 73 records · Page 4Linked to original sources

PubMed2001

Diurnal fluxes and the isotopomer ratios of N(2)O in a temperate grassland following urine amendment.

There is an urgent need to provide an accurate, up-to-date estimate of N(2)O fluxes in order that national policies can be developed to reduce emissions of N(2)O from soils. There are only limited data on temporal and diurnal patterns of N(2)O fluxes to the atmosphere, mainly due to constraints in the measurement techniques. In this paper we present the first terrestrial source values of N(2)O isotopomers and have measured and quantified the temporal and diurnal variability in N(2)O fluxes following urine addition to a grassland system in the UK. The experiment was carried out over a 2-week period on an artificially drained grassland system at the Institute of Grassland and Environmental Research (IGER), North Wyke, UK. Duplicate samples of urine, each of 2 L, were collected from dairy cows and applied to chambers (of area 0.16 m(2)). The N(2)O diurnal fluxes from urine and control (no urine) plots were measured by an automatic closed chamber technique. The isotopomers of N(2)O were obtained by analysing the gas samples collected during a peak emission phase. Soil and meteorological data were also collected. The results showed strong diurnal variations in N(2)O fluxes with minimum fluxes generally occurring between 7:00 and 14:00 hrs. The total cumulative flux of N(2)O for the whole experimental period was higher by a factor of >2 compared with estimates based on the daytime (between 10.00-16.00 hrs) measurements only. Therefore, measurements of N(2)O fluxes based on daily single exposure and expressed on a 24-h basis could impose a considerable bias and inaccuracy to the emission estimates, depending on when it was taken. The measured site preference values (difference between the centre (delta(15)Nalpha) and the end (delta(15)Nbeta) N atom of the N(2)O molecule) for soil-emitted N(2)O measured during our study were always lower than the tropospheric value. This work confirms that the enhanced tropospheric N(2)O site preference value could be the result of the back injection from the stratosphere. The intramolecular isotope ratios of nitrogen (delta(15)N) and oxygen (delta(18)O) and the site preference of the emitted N(2)O indicated that there was a shift of processes during the measurement period.

Algorithms↗

PubMed2001

Abnormalities of synapses and neurons in the hippocampus of neuropsin-deficient mice.

In the present study, we produced null-mutant mice of neuropsin, an extracellular matrix serine protease, to examine the neural functions of this protein particularly in the hippocampus. Golgi-Cox impregnation and Nissl-staining revealed morphological change of cell soma in the mutant mice compared to wild-type mice. However, Golgi-Cox impregnation revealed no apparent change in the dendritic arborization and spine density. Quantitative electronmicroscopic analysis revealed that number of asymmetrical synapses were significantly decreased in the stratum radiatum, the major terminal field of Schaffer-collaterals, whereas free boutons still holding synaptic vesicles but with no synaptic specialization were increased in number in the same microscopic fields. An increased number of parvalbumin-immunoreactive cells (known as fast spiking cells) in mutant was also observed. These results strongly suggest that neuropsin is involved in connectivity of a group of CA1 synapses and consequently in the hippocampal networking.

Animals↗

PubMed2001

Systematic separation and purification of elastase, gelatinase (matrix metalloproteinase 9), and collagenase (matrix metalloproteinase 8) from polymorphonuclear leukocytes in dialyzers previously used by patients with renal failure.

We developed a simple and effective method for the systematic separation and purification of human polymorphonuclear leukocyte (PMN) proteinases, elastase, gelatinase (matrix metalloproteinase 9, type IV collagenase), and collagenase (matrix metalloproteinase 8), derived from the extracts of hollow fiber dialyzers that had been utilized in the treatment of patients with renal failure. The fraction containing elastase was grossly separated from that containing gelatinase and collagenase by heparin-Sepharose chromatography and purified in an aprotinin column. The remaining two enzymes were then separated using the gelatin-Sepharose column after gel chromatography following ammonium sulfate precipitation. Gelatinase and collagenase were further purified by gelatin-Sepharose chromatography as a latent form and by collagen-Sepharose chromatography as an activated form. This novel method offers procedural advantages over existing methods that separate PMNs from the whole blood of volunteers for experimental research purposes.

Animals↗

PubMed2001

Involvement of three or more lymph nodes predicts poor prognosis in submucosal gastric carcinoma.

BACKGROUND: Multivariate analyses has shown that the status of lymph node metastasis and the depth of tumor penetration through the gastric wall are the most important prognostic factors in patients with advanced gastric carcinoma after curative operation. A clinicopathological study was carried out to clarify a simple and optimal prognostic indicator for early gastric cancer. METHODS: Retrospective analyses of 982 patients with early gastric cancer (562 with mucosal [M] and 420 with submucosal [SM] tumor) treated by gastrectomy with D2 lymph node dissection were performed. RESULTS: The incidence of lymph node metastasis from M and SM tumors was 2.5% (14/562) and 20.2% (85/420), respectively. There were no apparent prognostic indicators in patients with M tumors. In patients with SM tumors, the cancer-specific 5-year survival of those with lymph node metastasis was significantly lower than that of those without such metastasis (77.6% vs 98.2%; P < 0.001). An sharp decrease in survival was seen between patients with two positive nodes and those with three positive nodes, and the cancer-specific 5-year survival rate of patients with three or more metastatic lymph nodes was significantly lower than that of those with one or two nodes (P < 0.001; univariate analysis). Multivariate analysis revealed that the involvement of three or more lymph nodes was the sole independent prognostic determinant (P = 0.016); the level of nodal metastasis was not an independent prognostic factor (P = 0.384). All patients with N2 lymph node echelons (according to the Japanese Research Society for Gastric Cancer classification of the draining lymph nodes of the stomach) in the group with one or two positive nodes survived for more than 5 years. CONCLUSION: The sole independent prognostic factor in SM gastric cancer is the involvement of three or more metastatic lymph nodes. We suggest that this simple prognostic indicator for the follow-up of early gastric cancer, and this could lead to potentially effective adjuvant chemotherapy.

Adult↗

PubMed2001

Dose-finding phase I study of simultaneous weekly infusion with doxorubicin and docetaxel in patients with advanced breast cancer.

BACKGROUND: Combination therapy with doxorubicin (DOX) and docetaxel (DOC), given 3 weeks apart, is one of the standard regimens used for treating metastatic breast cancer, but it frequently generates febrile neutropenia. To find a safer regimen with less myelotoxicity and the appropriate dose intensity, we conducted a phase I study of simultaneous weekly infusion with DOX and DOC. METHODS: Twenty-five patients with advanced breast cancer were treated with an intravenous push-injection of DOX that was immediately followed by a 1-h infusion of DOC. This was repeated every week for at least 6 weeks. The premedication employed was three 4-mg doses of dexamethasone every week. Patients were divided into four groups for which the doses of DOX and DOC were escalated in 5-mg/m2 increments. RESULTS: In the 18 patients who were treated with DOX 15 or 20 mg/m2 and DOC 25 mg/m2, or lower, the regimen was found to be tolerable, without febrile episodes. The regimen with 20 mg/m2 of DOX and 30 mg/m2 of DOC was the maximum tolerated dose. Other indications of grade 3 toxicity included asthenia in 4% of patients, anorexia in 8%, and vomiting in 8%. Of the 25 patients, 14 had a partial response. The overall response rate was 56% (95% confidence interval [CI], 35% to 77%). The recommended dose for further trial was 20 mg/m2 of DOX and 25 mg/m2 of DOC. CONCLUSION: Simultaneous weekly infusion with DOX and DOC was feasible, with modest neutropenia and preserved dose intensity. This regimen may be helpful in the management of patients with advanced breast cancer.

Adult↗

PubMed2001

Toxicity and mutagenesis of chrysotile asbestos to Agrobacterium radiobacter.

The mutation of Agrobacterium radiobacter cells exposed to chrysotile asbestos was examined by the random amplified polymorphic DNA (RAPD) method. Approximately 1.4 kbp of DNA in A. radiobacter, which was not amplified strongly in the cells that were not exposed to asbestos, was amplified in the cells that were exposed to asbestos. Mutation in genomic DNA of A. radiobacter was found to be induced by asbestos. Specific DNA that was amplified by asbestos present in PCR products and that which exists latently in genomic DNA were cloned, and these sequences were then determined and compared. It was shown that one of the mutations by the asbestos in the A. radiobacter occurred only in the primer annealed region and was a point mutation or deletion.

Asbestos, Serpentine↗

PubMed2001

Efficacy of ethanol sclerotherapy for ovarian endometriomas.

OBJECTIVE: To evaluate the efficacy and limitations of ethanol sclerotherapy for ovarian endometriomas. METHODS: Retrospective investigation was made on 83 women with ovarian endometriomas who underwent transvaginal aspiration and ethanol sclerotherapy at Hiroshima City Hospital between 1993 and 1998. Furthermore, 30 who underwent laparoscopic cystectomy for ovarian endometriomas during the same period were investigated. RESULTS: Of the 74 women who were followed for more than 6 months, 11 (14.9%) had recurrent cysts. The recurrence rate of laparoscopic cystectomy was 3.8% (NS). The recurrence rate of cases instilled for less than 10 min was 62.5% (5/8), and that for 10 or more than 10 min was 9.1% (6/66) (P<0.001). The recurrence rate of cases having one cyst was 7.5% (4/53) and that of cases having two or more cysts was 33.3% (7/21) (P<0.05). CONCLUSION: Ethanol sclerotherapy is an effective and safe procedure and can be indicated for almost all ovarian endometriomas. Conduct of ethanol instillation for more than 10 min particularly for a case with a single endometrial cyst is considered most effective from the standpoint of recurrence.

Adult↗

PubMed2001

Isolation and characterisation of genomic and cDNA clones coding for a serine-, alanine-, and proline-rich protein of Trypanosoma cruzi.

We report here the isolation and characterisation of genomic and cDNA clones encoding a Serine-, Alanine-, and Proline-rich protein (SAP) of Trypanosoma cruzi metacyclic trypomastigotes. The deduced peptides translated from these clones were characterised by a high content of residues of alanine, proline, serine, glycine, valine, and threonine distributed in several repeats: P(2-4), S(2-3), A(2-3), AS, SA, PA, AP, SP, PS, and TP. The repeats are partially homologous to the serine-, alanine-, and proline-containing motifs of Leishmania major and Leishmania mexicana proteophosphoglycans. Genes coding for SAP are part of a polymorphic family whose members are linked to members of gp85/sialidase and mucin-like gene families. This is consistent with the hypothesis that this genetic organisation could be a means by which T. cruzi co-ordinates the expression of major surface proteins.

Amino Acid Sequence↗

PubMed2001

The mucin-like glycoprotein super-family of Trypanosoma cruzi: structure and biological roles.

Trypanosoma cruzi expresses at its surface large amounts of mucin-like glycoproteins. The T. cruzi mucins (TcMUC), a group of highly glycosylated GPI-anchored proteins rich in Thr, Ser, and Pro residues, are expressed in high copy numbers in both insect and mammalian stages of the parasite. These molecules are encoded by a multigene family and contain a unique type of glycosylation consisting of several sialylated O-glycans linked to the protein backbone via N-acetylglucosamine residues. The TcMUC are important because of their role in host cell invasion and the ability to induce secretion of proinflammatory cytokines and nitric oxide in activated macrophages. The TcMUC are also significant in being the major substrate for the cell surface trans-sialidase. In this review, we summarize the recent knowledge on the molecular structure and function of this family of T. cruzi glycoproteins.

Amino Acid Sequence↗

PubMed2001

Development of a three-dimensional jaw-tracking system implanted in the freely moving mouse.

A high-resolution mandibular tracking system was designed and tested in a freely moving mouse. A sensor unit, which consisted of four small magnetic sensors, was employed to trace small magnet movements in the three-dimensional space. After the sensor's output-to-displacement transformation equations were obtained from a multiple regression analysis of pre-experimental calibration data, the magnet and the sensors were transferred to the mouse, being kept at the same configuration as determined in the calibration system. In order to measure the three-dimensional jaw movements, the magnet was glued on the mandibular surface of the mouse and the sensor unit was implanted in the nasal bone. Jaw-movement trajectories were obtained as electrical signals from the sensors after being compensated by the output-to-displacement transformation equations of the sensors with a personal computer. This sensor system, applied to the freely moving mouse, could trace the jaw trajectories with an accuracy of better than 20 microm in three-dimensional space. Consequently, the typical pattern of the rhythmical jaw movements of the mouse during mastication was obtained. The mouse protruded the mandible to the most anterior position in the jaw-opening phase and retruded to it the most posterior position in the jaw-closing phase. This tracking system may also be applied to other small animals.

Animals↗

PubMed2001

In vivo measurement of the elastic modulus of the human periodontal ligament.

The present study was designated to determine the elastic properties of the periodontal ligament (PDL) in human subjects. A maxillary central incisor was experimentally translated so that stress or strain could be uniformly distributed in the PDL by applying a single force passing through the center of resistance. Displacements were measured under different magnitudes of load using a magnet-magnetic sensing system. From the load-displacement relations, Young's modulus of the PDL was calculated. The values determined were approximately 0.12 MPa under load ranging from 0 to 0.5 N, 0.25 MPa within the range of 0.5-1.0 N, 0.44 MPa under load 1.0-1.5 N, and between 0.69 and 0.96 MPa with 1.5-2.0 N. The values of Young's moduli increased almost exponentially with the increment of load due to a non-linear elasticity of the PDL.

Adult↗

PubMed2001

Effects of polaprezinc on lipid peroxidation, neutrophil accumulation, and TNF-alpha expression in rats with aspirin-induced gastric mucosal injury.

We examined the roles of lipid peroxidation, neutrophil accumulation, and inflammatory cytokines in the protective effect of polaprezinc against aspirin-induced gastric mucosal injury in rats. The intragastric administration of acidified aspirin induced hyperemia and hemorrhagic erosions in rat stomachs. The increase in the total gastric erosive area after aspirin administration was significantly inhibited in a dose-dependent manner by treatment with polaprezinc. The increases in thiobarbituric acid-reactive substances and tissue-associated myeloperoxidase activity 3 hr after aspirin administration were significantly inhibited by pretreatment with polaprezinc. The gastric concentration of TNF-alpha increased after aspirin administration, and the increase was also inhibited in a dose-dependent manner by treatment with polaprezinc. The peak expression of TNF-alpha mRNA 1 hr after aspirin administration was inhibited by 30 mg/kg of polaprezinc. Based on these data, the beneficial effects of polaprezinc on aspirin-induced gastric mucosal injury may be attributed to its antioxidative and antiinflammatory properties.

Animals↗

PubMed2001

The broad-spectrum anti-emetic activity of AS-8112, a novel dopamine D2, D3 and 5-HT3 receptors antagonist.

The anti-emetic and pharmacological profile of AS-8112 ((R)-5-bromo-N-(1-ethyl-4-methylhexahydro-1H-1,4-diazepin-6-yl)-2-methoxy-6-methylamino-3-pyridinecarboxamide.2 fumarate), a novel and potent dopamine D2, D3 and 5-hydroxytryptamine-3 (5-HT3) receptors ligand, was investigated in the present study. In guinea-pig isolated colon, AS-8112 produced a rightward shift of the concentration-response curves of 2-methyl-5HT, a 5-HT3 receptor agonist (pA2 value of 7.04). Other 5-HT3 receptor antagonists also produced such a shift in the following antagonistic-potency order: granisetron> ondansetron=AS-8112>>metoclopramide. In mice, AS-8112 (1.0 - 3.0 mg kg(-1) s.c.) potently inhibited hypothermia induced by the dopamine D3 receptor agonist; R(+)-7-OH-DPAT (R(+)-7-hydroxy-2-(N,N-di-n-propylamino)tetraline) (0.3 mg kg(-1) s.c.). Domperidone and haloperidol, which have affinity for dopamine D3 receptor, also inhibited R(+)-7-OH-DPAT-induced hypothermia. In ferrets or dogs, AS-8112 dose-dependently inhibited emesis induced by R(+)-7-OH-DPAT, apomorphine, morphine or cisplatin with ID50 values of 2.22 microg kg(-1) s.c., 10.5 microg kg(-1) s.c., 14.2 microg kg(-1) i.v. and 17.6 microg kg(-1) i.v., respectively. Moreover, oral administration of AS-8112 significantly inhibited emesis induced by these emetogens. AS-8112 (0.3 mg kg(-1) i.v.) significantly inhibited emesis induced by cyclophosphamide and doxorubicin. In conclusion, AS-8112 is a potent dopamine D2, D3 and 5-HT3 receptors antagonist, and a novel anti-emetic agent with a broad-spectrum of anti-emetic activity. These results suggest that this compound is worthy of clinical investigation.

Animals↗

PubMed2001

Pioglitazone, a specific PPAR-gamma ligand, inhibits aspirin-induced gastric mucosal injury in rats.

BACKGROUND: Neutrophils activation and tumour necrosis factor-alpha (TNF-alpha) induction play a critical role in aspirin-induced gastric mucosal injury. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a member of the nuclear hormone receptor superfamily, has recently been implicated as a regulator of inflammatory responses. The aim of the present study was to determine whether pioglitazone, a specific PPAR-gamma ligand, can ameliorate aspirin-induced gastric mucosal injury in rats, and whether the agent can inhibit the increase in neutrophil accumulation associated with TNF-alpha expression. METHODS: Aspirin-induced injury was produced by the intragastric administration of aspirin (200 mg/kg) and HCl (0.15 N, 8.0 mL/kg). Pioglitazone was given to the rats by gastric intubation 1 h before the aspirin administration. Thiobarbituric acid-reactive substances and tissue-associated myeloperoxidase activity were measured in gastric mucosa as indices of lipid peroxidation and neutrophil infiltration. The gastric concentration of TNF-alpha and the expression of TNF-alpha mRNA was determined by ELISA and reverse transcriptase-polymerase chain reaction. RESULTS: The intragastric administration of acidified aspirin induced hyperemia and haemorrhagic erosions in rat stomachs. The increase in the total gastric erosive area after aspirin administration was significantly inhibited by treatment with pioglitazone in a dose-dependent manner. The increases in thiobarbituric acid-reactive substances and myeloperoxidase activity after aspirin administration were both significantly inhibited by pre-treatment with pioglitazone (10 mg/kg). The gastric content of TNF-alpha increased and the expression of TNF-alpha mRNA was up-regulated after aspirin treatment. However, the peak TNF-alpha mRNA expression 1 h after aspirin administration was inhibited by pioglitazone. CONCLUSION: Based on these data, the beneficial effects of pioglitazone on aspirin-induced gastric mucosal injury may be attributed to its anti-inflammatory properties.

Animals↗

PubMed2001

Differential effect of phosphodiesterase inhibitors on IL-13 release from peripheral blood mononuclear cells.

Increased cyclic AMP (cAMP)-phosphodiesterase (PDE) activity in peripheral blood leucocytes is associated with the immunological inflammation that characterizes allergic diseases, such as atopic dermatitis and allergic rhinitis. Recently, it has been found that IL-13 has similar biological functions to IL-4. The aim of this study was to investigate the possible involvement of cAMP-PDE activity on IL-13 release from peripheral blood mononuclears cells (PBMC) from atopic asthma patients. Phytohaemagglutinin (PHA)-induced IL-13 release from PBMC was concentration-dependently inhibited by rolipram, a type 4 PDE inhibitor, as well as by dibutyryl cAMP, a membrane-permeant cAMP analogue. However, theophylline, a non-specific PDE inhibitor, and cilostazol, a type 3 PDE inhibitor, failed to inhibit IL-13 release. The inhibitory effect of rolipram was enhanced by the addition of forskolin (10(-4) m), an adenylyl cyclase stimulator. PHA itself did not alter the intracellular cAMP level. Rolipram concentration-dependently increased cAMP level in PHA-stimulated PBMC, and this increase was synergistically facilitated by the addition of forskolin (10(-4) m). These results suggest that type 4 PDE inhibitors, alone or synergistically in combination with forskolin, inhibit PHA-induced IL-13 release from PBMC of atopic asthma patients by elevating intracellular cAMP concentrations. These inhibitors have the potential to exert an anti-inflammatory effect by inhibiting IL-13 production in allergic diseases such as atopic asthma.

Adult↗

PubMed2001

Experimental evaluation of initial tooth displacement, center of resistance, and center of rotation under the influence of an orthodontic force.

The purpose of this study was to determine the location of the center of resistance and the center of rotation of the maxillary central incisors under the influence of a single simple force and to investigate related geometric parameters of the teeth and the surrounding periodontal tissues. By measuring the initial displacement of the central incisors with a magnetic sensing system, the location of the center of resistance and the centers of rotation associated with various forces were determined in 3 human subjects. The results show that the location of the center of resistance of the maxillary central incisor depends on the palatal bone level and is at approximately two-thirds of the palatal alveolar bone height, measured from the root apex. A greater moment-to-force ratio is needed for any controlled movement of the maxillary incisors during retraction in patients with reduced palatal alveolar bone height. This study suggests a method for estimating the location of the center of resistance of a tooth.

Alveolar Bone Loss↗

PubMed2001

In vivo determination of the centres of resistance of maxillary anterior teeth subjected to retraction forces.

This study was designed to locate the centres of resistance of consolidated units of two, four, and six anterior teeth during retraction in two human subjects. Initial displacements of these units were separately measured when retraction forces were applied at different levels by means of a device for displacement measurement using magnetic sensors and magnets. By calculating the angle of rotation from the displacements measured, the location of the centre of resistance was determined for each unit. The results showed that the centres of resistance of the two- and four-incisor units were approximately at the same position, whilst that of the six-tooth unit was observed to be more incisal. Clinically, this finding indicates that translation can be achieved with a smaller amount of moment-to-force ratio in en masse retraction than in two- or four-incisor retraction. The results also indicate that the location of the centre of resistance of the anterior segment during retraction may depend on the palatal alveolar bone height, rather than on the labial alveolar bone height.

Adult↗

PubMed2001

Placentomegaly in cloned mouse concepti caused by expansion of the spongiotrophoblast layer.

Hypertrophic placenta, or placentomegaly, has been reported in cloned cattle and mouse concepti, although their placentation processes are quite different from each other. It is therefore tempting to assume that common mechanisms underlie the impact of somatic cell cloning on development of the trophoblast cell lineage that gives rise to the greater part of fetal placenta. To characterize the nature of placentomegaly in cloned mouse concepti, we histologically examined term cloned mouse placentas and assessed expression of a number of genes. A prominent morphological abnormality commonly found among all cloned mouse placentas examined was expansion of the spongiotrophoblast layer, with an increased number of glycogen cells and enlarged spongiotrophoblast cells. Enlargement of trophoblast giant cells and disorganization of the labyrinth layer were also seen. Despite the morphological abnormalities, in situ hybridization analysis of spatiotemporally regulated placenta-specific genes did not reveal any drastic disturbances. Although repression of some imprinted genes was found in Northern hybridization analysis, it was concluded that this was mostly due to the reduced proportion of the labyrinth layer in the entire placenta, not to impaired transcriptional activity. Interestingly, however, cloned mouse fetuses appeared to be smaller than those of litter size-matched controls, suggesting that cloned mouse fetuses were under a latent negative effect on their growth, probably because the placentas are not fully functional. Thus, a major cause of placentomegaly is expansion of the spongiotrophoblast layer, which consequently disturbs the architecture of the layers in the placenta and partially damages its function.

Animals↗