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Biomedical subjects

Y Maeda

Publications and source records attributed to Y Maeda.

At least 595 records · Page 33Linked to original sources
PubMed1993

Vasopressin and oxytocin receptors coupled to Ca2+ mobilization in rat inner medullary collecting duct.

In renal collecting duct epithelial cells, arginine vasopressin (AVP) at greater than nanomolar concentrations has been reported to transiently increase intracellular free calcium ([Ca2+]i) in a manner consistent with activation of the phosphoinositide pathway. To investigate whether any of the known neurohypophysial hormone subtypes are involved, we measured [Ca2+]i in microdissected rat terminal inner medullary collecting duct (IMCD) using fura-2. To allow quantitative comparisons of the response under different conditions, we determined the areas under the response curves (in nM.min) over 1.5 min using numerical integration. AVP, the V1b-receptor agonist [deamino1,D-3-(pyridyl)Ala2,Arg8]vasopressin, the V2-receptor agonist 1-desamino-8-D-arginine vasopressin, oxytocin, and the selective oxytocin-receptor agonist [Thr4,Gly7]oxytocin (TG-OXT), each at 10 nM, significantly increased [Ca2+]i (69.52 +/- 10.25, 27.0 +/- 11.7, 24.33 +/- 5.83, 14.75 +/- 2.81, and 14.57 +/- 3.50 nM.min, respectively). In contrast, a V1a-selective agonist ([Phe2,Ile3,Orn8]vasopressin) did not increase [Ca2+]i (0.43 +/- 2.36 nM.min). In desensitization studies, challenge with 10 nM AVP or TG-OXT completely prevented a rise in [Ca2+]i in response to immediate rechallenge with the same agent, but not the other, demonstrating homologous desensitization. The lack of cross-desensitization implies that at least two receptors are present that can trigger a rise in [Ca2+]i in response to neurohypophysial hormones. Antagonists for oxytocin ([des-glycinamide9,d(CH2)5(1),O-Me-Tyr2,Thr4,Orn8]vaso tocin), V2 ([d(CH2)5(1),D-Ile2,Ile4,Arg8]vasopressin), and V1a ([d(CH2)5(1),O-Me-Tyr2,Arg8]vasopressin) receptors partially inhibited the [Ca2+]i response induced by 10 nM AVP (89.5, 81.6, and 51.4% inhibition, respectively). These data are consistent with the view that both an oxytocin receptor and a vasopressin receptor are coupled to a [Ca2+]i mobilization response in rat terminal IMCD. This vasopressin receptor is distinct from both the V1a receptor and the V2 receptor and may be either the V1b receptor or a novel vasopressin receptor subtype.

Animals↗
PubMed1993

Dual actions of vasopressin and oxytocin in regulation of water permeability in terminal collecting duct.

We conducted studies in isolated perfused terminal inner medullary collecting ducts (IMCD) from rats to investigate the roles of oxytocin and vasopressin in the regulation of osmotic water permeability. Vasopressin and oxytocin were found to have both stimulatory effects (at 0.1 nM) and inhibitory effects (at 10 nM) on osmotic water permeability. Measurements of adenosine 3',5'-cyclic monophosphate (cAMP) production demonstrated that both vasopressin and oxytocin increase cAMP production. Both the selective oxytocin-receptor agonist [Thr4,Gly7]oxytocin (10 nM) and the selective V1b agonist [deamino1,D-3-(pyridyl)Ala2,Arg8]vasopressin (10 nM) inhibited vasopressin-stimulated osmotic water permeability. In contrast, the selective V1a vasopressin-receptor agonist [Phe2,Ile3,Orn8]vasopressin (10 nM) had no effect on vasopressin-stimulated osmotic water permeability. These effects on water permeability correlated with the ability of the agents to transiently increase intracellular free calcium. The oxytocin/vasopressin-receptor antagonist [des-glycinamide9,d(CH2)5(1),O-Me-Tyr2,Thr4,Orn8]vasot ocin, which almost completely blocks vasopressin-induced calcium mobilization, also blocked the ability of 10 nM vasopressin to inhibit osmotic water permeability relative to that found with 0.1 nM vasopressin. We conclude the following. 1) Oxytocin, like vasopressin, has dual effects on osmotic water permeability, increasing it at subnanomolar concentrations and inhibiting it at suprananomolar concentrations. 2) Oxytocin, like vasopressin, can increase cAMP production, perhaps accounting for the increase in water permeability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Sulfated glucuronyl glycolipids and gangliosides in the optic nerve of humans.

Pathologically delayed visual evoked potentials may be present in patients with neuropathy associated with IgM M-proteinemia, which is directed against myelin-associated glycoprotein and sulfated glucuronyl glycolipids (SGGLs), but there are no reports of these antigens in the optic nerve. We recently examined human optic nerve and occipital lobe tissues for the occurrence of SGGLs using the technique of immunostaining on thin-layer chromatographic plates and found them in the optic nerve, but not the occipital lobe. SGGLs in the optic nerve may represent target antigens for CNS involvement by the M-protein in patients with neuropathy. We also studied the ganglioside composition of the optic nerve and found it different from that of the brain. Human optic nerve is characterized by an abundance of the b-series gangliosides, including GD1b, GT1b, and GQ1b. GD1a, which is usually a major component of brain gangliosides, is only a minor species of the optic nerve ganglioside fraction.

Chromatography, Thin Layer↗
PubMed1993

Immunoblotting of contractile and cytoskeletal proteins of canine basilar artery in vasospasm.

Vasospasm was produced in the canine basilar arteries by a two-hemorrhage method, and voltage- and receptor-dependent contractions of the normal canine basilar arteries were induced by local applications of potassium chloride (KCI) and serotonin, respectively, after transclival exposure. Actin, myosin, desmin, filamin, talin, vinculin, and alpha-actinin in the basilar artery were studied by immunoblotting. The immunoblots showed a decrease or loss in immunoreactivity of some native proteins and generation of protein fragments, smaller in size than native proteins, in spastic, KCI, and serotonin groups, indicating a proteolytic degradation. In the spastic group on Day 2, actin, desmin, and filamin were usually degraded slightly; myosin moderately; and talin and alpha-actinin substantially. Vinculin and metavinculin remained intact. In the spastic group on Day 7, actin and desmin were usually decomposed slightly; myosin, filamin, and vinculin substantially; and talin, metavinculin, and alpha-actinin markedly. In the KCI and serotonin groups, slight degradation was usually observed in filamin, often in alpha-actinin, and occasionally in actin, whereas desmin, vinculin, and metavinculin were not degraded. In addition, myosin was usually degraded moderately in the KCI group and slightly in the serotonin group, and talin was generally decomposed slightly in the KCI group and moderately in the serotonin group. The degraded fragments, although variable in number and immunoreactivity, were similar in size in the three groups. We suggest that the intracellular devices responsible for contraction of the basilar arteries are degraded more severely in the spastic group than in the KCI or serotonin group, probably by similar proteolytic mechanism and progressively with the passage of time after subarachnoid hemorrhage in vasospasm.

Animals↗
PubMed1993

Effects of aluminium-containing antacid on bioavailability of ofloxacin following oral administration of pivaloyloxymethyl ester of ofloxacin as prodrug.

We newly synthesized a pivaloyloxymethyl ester of ofloxacin (OFLX-PVM) as prodrug in order to avoid the chelate formation between new quinolone and metal cations such as Al3+, Mg2+, Ca2+, or Fe2+ in the gastrointestinal tract. This compound was rapidly hydrolyzed in an incubation experiment by 43% in plasma, by 92% in small intestinal mucosal homogenates, and by 97% in liver homogenates during 0.5 h incubation, but was resistant to hydrolysis by pancreatic enzymes. In everted gut sac experiments, this compound was efficiently absorbed even in the presence of aluminium ion, whereas the absorption of ofloxacin (OFLX) was decreased significantly by the presence of aluminium ion. Minimal inhibitory concentration (MIC) values of OFLX-PVM were far higher than OFLX. Effects of aluminium hydroxide on the oral bioavailability of OFLX and OFLX-PVM were investigated in rabbits. The area under the plasma concentration-versus-time curve from zero to 24 h (AUC0-24h) following oral administration of OFLX was decreased significantly by 47.6% by combined administration with aluminium hydroxide, but AUC0-24h values of OFLX-PVM coadministered with and without aluminium hydroxide were similar to that of OFLX alone. These observations indicate that this new compound is likely to offer a prodrug for avoidance of interaction between new quinolone and metal cations.

Administration, Oral↗
PubMed1993

The short- and long-term prognosis for acute myocardial infarction after emergency coronary angioplasty.

The short- and long-term prognosis for acute myocardial infarction after reperfusion was examined in 175 patients with successful emergency angioplasty and in 29 failed cases. During hospitalization, more cardiac events occurred in the failed group than in the successful group (58.6% versus 12.6%; p < 0.001), especially cardiac death and coronary bypass surgery (27.6% versus 4.0%, and 41.4% versus 4.6%; p < 0.001, respectively). The only difference found in the incidence of post-discharge cardiac events was a higher frequency of cardiac death in the failed group (9.5% versus 1.2%; p < 0.02). The failed group also had a lower cumulative survival rate at 5 years (69.0% versus 95.3%; p < 0.01). Cox proportional hazard analysis showed that the results of angioplasty, cardiac index, peak creatine kinase level, and the number of diseased vessels were significant independent variables for the prediction of subsequent cardiac death at long-term follow-up. Thus, successful reperfusion by emergency angioplasty improved the prognosis of acute myocardial infarction, even when other important variables were considered.

Adult↗
PubMed1993

Calpain-calpastatin system of canine basilar artery in vasospasm.

Vasospasm was produced in the canine basilar artery by a two-hemorrhage method, while contraction was induced in the normal canine basilar artery by a local application of KCl or serotonin after transclival exposure. The control animals were injected with saline instead of fresh blood. The activation of mu-calpain, a Ca(++)-dependent neutral protease, in the basilar artery was studied by evaluating the conversion from its inactivated into its activated form on immunoblots. In addition, the activity of calpastatin, an intrinsic inhibitor of calpain, in the basilar artery was determined by assay. The majority of the mu-calpain was inactivated in the control group. In the spastic group, mu-calpain was generally activated markedly in the early stage of vasospasm and moderately thereafter. The contraction induced by KCl or serotonin application was classified into the early phasic and the later tonic stages; mu-calpain was usually activated in the phasic stage and inactivated in the tonic stage. Calpastatin activity was significantly decreased during vasospasm, whereas it was not significantly changed in KCl- or serotonin-induced contraction. The final activity of mu-calpain results from the balance of mu-calpain and calpastatin. This suggests that mu-calpain activity was enhanced continuously in the spastic group and transiently in the KCl or serotonin group, and that the continuous activation of mu-calpain during vasospasm probably induced more proteolytic changes compared to those in the KCl or serotonin group.

Animals↗
PubMed1993

Immunopathological stain of lipoarabinomannan-B (LAM-B) for diagnosis of leprosy.

We developed an immunopathological staining of LAM-B antigen in formalin-fixed paraffin-embedded tissues, and compared it with, PGL-I immunostaining, Fite Faraco's stain and periodic acid carbol pararosaniline (PACPR) stain. Out of the total 28 leprosy cases, 27 were positive to LAM-B immunostaining while 23 were positive to PGL-I stain. Fite's stain was positive in 21 cases while PACPR stain was positive in 24 cases. In scrofuloderma, LAM-B antigen was observed only in the granuloma while no other positive findings were noted with other stains. Normal skin did not give any positive findings with any of the stains. Other dermatoses showed no positive findings to any of the stains tested. LAM-B staining was observed in the nerve even in the absence of bacilli in leprosy tissues. Presence of LAM-B in the cutaneous nerves is helpful in discriminating leprosy from other mycobacterioses. Considering the high sensitivity of LAM-B and the predilection of M. leprae for the nerves, we concluded that LAM-B staining can be a useful new tool in the prompt diagnosis of leprosy, especially in suspected or early cases.

Diagnosis, Differential↗
PubMed1993

Comparative studies of Ca(2+)-ATPase activity in epiphysis of tibiatarsus of quail lines selected for body weight.

1. Ca2+ concentration in blood plasma and Ca(2+)-ATPase activity in epiphysis of tibia at 3 and 15 weeks of age were compared among three quail lines (LL, RR and SS) selected for body weight. 2. The Ca2+ concentrations in blood plasma were higher in order of LL, RR and SS at 3 and 15 weeks of age in both sexes. Ca2+ concentrations in blood plasma at 3 weeks of age were lower than those of 15 weeks of age in both sexes. 3. At 15 weeks of age, the concentration of females was significantly higher than that of males in all lines. 4. The activities of Ca(2+)-ATPase in epiphysis of tibia was higher in order of SS, RR and LL at both ages and in both sexes. 5. The activities of Ca(2+)-ATPase at 3 weeks of age were significantly higher than those of 15 weeks of age in all lines. 6. These results suggest that the selection for body weight changed the concentration of Ca2+ in blood plasma and the activities of Ca(2+)-ATPase in epiphysis of tibia, parallel to the change of tibia length.

Animals↗
PubMed1993

Suppression of tumourigenicity in human colon carcinoma cells by introduction of normal chromosome 1p36 region.

Development of colon carcinomas appears to be associated with inactivation of multiple tumour suppressor genes. Cytogenetic and DNA analyses of colon carcinomas have detected a high frequency of chromosome 1p deletion, which suggests the presence of a tumour suppressor gene. We therefore introduced normal human chromosome 1 into colon carcinoma COKFu cells, through microcell hybridization. Six clones of hybrid cells containing normal chromosome 1 were obtained, four of which had a small fragment of the introduced chromosome 1, including 1p36-34. The morphology of hybrid cells with chromosome 1 markedly altered to a flat shape. The cloning efficiency of all six hybrid cells in soft agar was significantly reduced, and the tumourigenicity in athymic nude mice was completely suppressed. Hybrid cells containing only the region of 1p36-34, as well as those containing intact chromosome 1, showed suppressed transformed phenotype. Furthermore, several tumourigenic revertant cells were obtained from the hybrid cells. These revertant cells had a morphology similar to that of COKFu cells, and were found to have lost the 1p36 region from the introduced chromosome 1. These results indicate that a normal chromosome 1p36 carries a tumour suppressor gene for colon carcinogenesis.

Adenocarcinoma↗
PubMed1993

Increase of Thy-1 antigen on the thymocytes accompanied with their augmented adhesion capacity to thymic epithelial cells in the mice infected with Listeria monocytogenes.

It becomes increasingly clear that adhesion systems such as CD2/LFA-3 (lymphocyte function-associated antigen-3), LFA-1/ICAM-1 (intercellular adhesion molecule-1) and Thy-1/putative Thy-1 ligand participate in the association between murine thymocytes and thymic epithelial cells. In the present study, thymocytes showed an increase in surface Thy-1 levels in mice infected with Listeria monocytogenes, but no significant changes in the levels of CD2 or LFA-1. No alteration was found either in the ratio of CD3high/CD3low/CD3- or in that of CD4/CD8 subsets in these thymocytes compared with uninfected control thymocytes which excluded the possibility of enrichment of 'cortical thymocytes' with Thy-1high/CD3low/CD4+ CD8+ in the thymocyte population of infected mice. Moreover such Thy-1high thymocytes exhibited a highly augmented ability of adhesion to a thymic epithelial cell line due to the increase of surface Thy-1 antigens as an adhesion molecule. At such intervals after infection, the total number of thymocytes was found to be reduced. These results suggest that the expression level of surface Thy-1 on thymocytes is regulated in response to in vivo stimulation and may play a role in the intrathymic development of thymocytes by affecting the adhesion of thymocytes with thymic stromal cells. The implication of the enhanced ability of adhesion in the decrease in the number of thymocytes is discussed.

Animals↗
PubMed1993

Parvovirus B19-related lymphadenopathy.

We tested whether parvovirus B19 (PVB19) is involved in benign lymph node swelling as a causative agent. The serum specimens from 13 patients with lymph node swelling of unidentified cause were tested for IgM and IgG antibody against PVB19 by Western blot analysis. Five patients had IgM antibody, and PVB19 DNA was detected in the serum from one of them by dot-blot analysis, suggesting the recent PVB19 infection and its involvement in lymph node swelling of these patients. Clinical and haematological features of the patients are also discussed.

Adolescent↗
PubMed1993

[The allergic reaction to acid protease released by Candida albicans].

The species of Candida albicans (C. albicans) are known to colonize mucocutaneous regions as part of the endogenous flora. C. albicans is also known as an important allergen in human allergic diseases. However, the major allergen of C. albicans has not been identified yet. Acid protease released from C. albicans (CAAP) cleaves IgA or the secretory component to enable C. albicans to colonize on the mucous membrane. In this study, using CAAP and crude Candida antigen as challenging antigens, we carried out conjunctival provocation tests (CPT) on 68 adult bronchial asthmatic patients who showed immediate positive skin reactions to crude Candida antigen. In several patients we performed serum IgE antibody (RAST), histamine release from peripheral leukocytes (HRT) and bronchial provocation tests (BPT) to CAAP. Six of the 8 patients who showed positive CPT to crude Candida antigen (75%) showed positive CPT responses to CAAP. On the other hand, only 1 of the 59 patients who showed negative CPT to crude Candida antigen (1.7%) showed positive CPT reactions to CAAP. Two female patients showed positive RAST and HRT to both crude Candida and CAAP. They also showed positive CPT and BPT. One patient had positive RAST results but negative HRT, CPT and BPT results. These results show that CAAP is an important allergen for atopic patients allergic to C. albicans.

Adult↗
PubMed1993

A case report of epithelioid leiomyosarcoma of transverse mesocolon: diagnosis and treatment.

A case of epithelioid leiomyosarcoma of the transverse mesocolon in a 45-year-old man was reported. The patient had a rapidly growing mass in the left upper quadrant. Ultrasonography, gastrointestinography, and abdominal computed tomography showed that the mass was separated from the pancreas, the gastrointestinal tract, and the retroperitoneal organs. Preoperatively the primary origin of this tumor was related to the transverse mesocolon. On laparotomy the tumor of 5cm by 6cm by 3cm in size was found in the anterior left of the transverse mesocolon and the mass was resected entirely. The patient is well 18 months after surgical treatment with no evidence of recurrence.

Humans↗
PubMed1993

The inhibitory effects of salmon calcitonin on intrathecally-injected N-methyl-D-aspartate-induced aversive behavior in mice.

The effects of salmon calcitonin (SCT) on intrathecally-injected N-methyl-D-aspartate (NMDA)-induced aversive behavior were investigated to clarify the involvement of the NMDA receptor/ionophore complex on the analgesic effects of SCT. Intracerebroventricular (i.c.v.) injection of SCT significantly inhibited acetic acid-induced writhing. Intrathecal (i.t.) injection of NMDA (0.25-1.0 nmol/mouse) dose-dependently induced aversive behavior such as scratching and tail biting. SCT at the doses of 0.01 and 0.1 IU/mouse (i.c.v.) significantly inhibited the NMDA-induced aversive behavior. This inhibitory effects of SCT on NMDA (i.t.)-induced aversive behavior were neither potentiated nor antagonized by i.c.v. injection of MK-801 and NMDA, respectively. Further, MK-801 (i.c.v.) and NMDA (i.c.v.) themselves did not affect the NMDA (i.t.)-induced aversive behavior. These results suggest that the NMDA receptor/ionophore complex in the brain is not directly involved in the antinociceptive effects of intracerebrally-injected SCT.

Analgesics↗
PubMed1993

[A study of sensitization and symptoms in adult asthmatics who keep cat and dog].

We studied hypersensitivity to cats and dogs in three hundred adult asthmatics who kept them. Some findings were noted as follows. 1) The mean duration for which cats were kept was 6.2 +/- 10.1 (1 S.D.) years and that for dogs was 4.2 +/- 9.6 (1 S.D.) years. 2) The positive rate in intradermal tests to dog dander was 7% and to cat hair-epithelium 32%. The positive RAST (score > or = 2) rate to cat epithelium was 36.1%, to dog dander 31.6% and to dog epithelium 7.3% respectively. 3) Eleven to 18% of the dog keepers and 23 to 36% of the cat keepers whose RAST score were positive were aware of the relationship between pets and asthma, specifically concerning eye and nose symptoms. 4) Thirty percent of the cat and dog keepers had become sensitized to them after keeping them for under one year. The positive RAST rate was unchanged in those who kept Japanese native dogs but increased in those who kept foreign breeds after 3 to 6 years. The rate of sensitization rate to cats tended to increase along with the period for which they were kept. 5) Dog dander RAST scores among the foreign breed keepers were significantly higher than those among the native dog keepers. If the dog breed was the same, the RAST score was not higher if the dog was kept indoors than if it was kept outdoors. We concluded that a possible reason why the RAST scores were higher among those who kept foreign breeds was that foreign breeds have stronger allergenicity.

Adult↗
PubMed1993

[Changes in antigen-specific IgG, IgG4, and IgE antibodies in patients receiving immunotherapy with house-dust extract].

We measured allergen-specific IgG, IgG4, IgE antibodies and total IgE in sera from 64 patients who were receiving conventional immunotherapy (IT) with house dust (HD) extract. The sera were taken before and after IT. To measure allergen-specific antibodies, we used crude DF antigen, Der f I and Der f II for IgG and IgG4 antibodies, and crude DF antigen for IgE antibodies. The patients were divided into 3 groups: very short term group (IT period < 2 years, n = 9); short term group (2 < = IT period < 7 years, n = 25); long term group (7 years < = IT period, n = 30). The specific IgG antibodies for DF crude antigen did not change in any group. The specific IgG antibodies for Der f I and Der f II increased in the short term group and in the long term group. The specific IgG4 antibodies for all three antigens increased remarkably in the short term group and in the long term group. In the very short term group, however, the specific IgG4 antibodies did not increase for any antigen. Total IgE and the specific IgG antibodies did not change through IT. The specific IgG4 antibodies increased significantly through IT, but the time course of the increment of the IgG4 antibodies was not parallel with the clinical course of IT.

Adult↗