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Biomedical subjects

A Yoshida

Publications and source records attributed to A Yoshida.

At least 19 recordsLinked to original sources
PubMed2000

G(i1) and G(oA) differentially determine kinetic efficacies of agonists for kappa-opioid receptor.

We examined the diversity of single receptor function by measuring receptor-G protein coupling in the baculovirus-Sf21 expression system. In comparative studies using Sf21 cell membranes expressing kappa-opioid receptor (KOR) plus Galpha(i1)beta(1)gamma(2) or KOR plus Galpha(oA)beta(1)gamma(2), there was no significant difference between both preparations in the K(i) values of various kappa-opioid ligands for the displacement of [(3)H]U69593 binding. However, a marked difference in the rank order of agonists to stimulate [(35)S]GTPgammaS binding was observed between both preparations. These findings suggest that agonist efficacy is dependent on the population of different G proteins expressed in various tissues.

Animals↗
PubMed2000

A role of mast cell glycosaminoglycans for the immunological expulsion of intestinal nematode, Strongyloides venezuelensis.

We examined effects of mast cell glycosaminoglycans on the establishment of the intestinal nematode, Strongyloides venezuelensis, in the mouse small intestine. When intestinal mastocytosis occurred, surgically implanted adult worms could not invade and establish in the intestinal mucosa. In mast cell-deficient W/Wv mice, inhibition of adult worm invasion was not evident as compared with littermate +/+ control mice. Mucosal mastocytosis and inhibition of S. venezuelensis adult worm mucosal invasion was tightly correlated. To determine effector molecules for the invasion inhibition, adult worms were implanted with various sulfated carbohydrates including mast cell glycosaminoglycans. Among sulfated carbohydrates tested, chondroitin sulfate (ChS)-A, ChS-E, heparin, and dextran sulfate inhibited invasion of adult worms into intestinal mucosa in vivo. No significant inhibition was observed with ChS-C, desulfated chondroitin, and dextran. ChS-E, heparin, and dextran sulfate inhibited adhesion of S. venezuelensis adult worms to plastic surfaces in vitro. Furthermore, binding of intestinal epithelial cells to adhesion substances of S. venezuelensis, which have been implicated in mucosal invasion, was inhibited by ChS-E, heparin, and dextran sulfate. Because adult worms of S. venezuelensis were actively moving in the intestinal mucosa, probably exiting and reentering during infection, the possible expulsion mechanism for S. venezuelensis is inhibition by mast cell glycosaminoglycans of attachment and subsequent invasion of adult worms into intestinal epithelium.

Animals↗
PubMed2000

Identification of signal substances in synapses made between primary afferents and their associated axon terminals in the rat trigeminal sensory nuclei.

The relationships between primary afferent terminals (PATs) and their associated presynaptic terminals in the rat trigeminal sensory nuclear complex (TSNC) were examined with special reference to amino acid transmitters glutamate (Glu) and gamma-aminobutyric acid (GABA). Primary afferent terminals anterogradely labeled from the trigeminal ganglion with the B subunit of cholera toxin conjugated to horseradish peroxidase (CTB-HRP) were sectioned for electron microscopy. Serial sections from the principal nucleus (Vp), dorsomedial parts of the oral and interpolar nuclei (Vdm), and lamina III/IV of caudal nucleus (Vc) were immunostained for Glu and GABA by using a postembedding immunogold technique. The tracer, CTB-HRP to the trigeminal ganglion, preferentially labeled myelinated primary afferents. Sections immunostained with Glu antiserum showed that most labeled PATs were enriched with immunoreactivity (IR) for Glu. The Glu-IR PATs contained clear, round, synaptic vesicles and formed asymmetric synaptic contacts with somata or dendrites. They were frequently postsynaptic to, unlabeled axon terminals filled with a mixture of clear, round, oval, and flattened vesicles (p-endings), with symmetric synaptic junctions. The frequency of synapses onto somata or primary dendrites per Glu-IR PAT was higher in the Vdm than in either the Vp or Vc lamina III/IV. The frequency of contacts of the p-endings per Glu-IR PAT was higher in the Vp than in the Vdm and Vc lamina III/IV. Sections immunostained with GABA antiserum showed that most axon terminals presynaptic to PATs were enriched with GABA in the three nuclei. The GABA-IR axon terminals and their postsynaptic PATs had a similar ultrastructural character to p-endings and their postsynaptic Glu-IR PATs, respectively. The present study suggests that primary afferent neurons with large-caliber fibers use glutamate as a neurotransmitter and are subject to presynaptic modulation by GABAergic fibers.

Animals↗
PubMed2000

Advantage of gene gun-mediated over intramuscular inoculation of plasmid DNA vaccine in reproducible induction of specific immune responses.

Utilizing a plasmid DNA encoding a single cytotoxic T lymphocyte (CTL) epitope and that encoding ovalbumin (OVA), we compared the reproducibility in the induction of immune responses by gene gun and intramuscular immunization. As compared to intramuscular inoculation, gene gun DNA immunization appeared to bring about highly reproducible and reliable results in the induction of specific CTL and IFN-gamma production to the CTL epitope and production of anti-OVA IgG. The results obtained by intramuscular inoculation vary significantly. Our data shown here strongly suggest that gene gun immunization of skin is a much more reliable method for DNA vaccination to induce effective immune responses in an animal model.

Animals↗
PubMed2000

Vzg-1/lysophosphatidic acid-receptor involved in peripheral pain transmission.

The nociception by intraplantar (i.pl.) lysophosphatidic acid (LPA) injection was significantly, but partially blocked when mice received intrathecal (i.t.) antisense oligodeoxynucleotide treatment for the vzg-1 type LPA-receptor. The residual LPA-nociception observed under the condition of pertussis toxin-treatment, which is expected to block presynaptic contribution, was abolished by diphenhydramine (i.pl.), an H1-type histamine receptor antagonist. Taking into account that vzg-1 mRNA was detected in the dorsal root ganglion by RT-PCR method, these findings suggest that the LPA-induced nociception is attributed to the mechanism through vzg-1 receptor on nociceptor endings, and to that through unidentified LPA-receptor on peripheral, possibly mast cells.

Anesthetics, Local↗
PubMed2000

ASCA Observation of the Quiescent X-Ray Counterpart to SGR 1627-41.

We present a 2-10 keV ASCA observation of the field around the soft gamma repeater SGR 1627-41. A quiescent X-ray source, whose position is consistent both with that of a recently discovered BeppoSAX X-ray source and with the Interplanetary Network localization for this soft gamma repeater, was detected in this observation. In 2-10 keV X-rays, the spectrum of the X-ray source may be fit equally well by a power-law, blackbody, or bremsstrahlung function, with unabsorbed flux approximately 5x10-12 ergs cm-2 s-1. We do not confirm a continuation of a fading trend in the flux, and we find no evidence for periodicity, both of which were noted in the earlier BeppoSAX observations.

Journal Article↗
PubMed2000

Scanning laser ophthalmoscope correlations with biomicroscopic findings and foveal function after macular hole closure.

OBJECTIVE: To investigate the relation between foveal findings and visual function in eyes with a resolved idiopathic macular hole after vitreous surgery. METHODS: We divided 28 eyes with postoperative idiopathic macular hole resolution into 3 groups based on postoperative biomicroscopic foveal findings of complete closure, partial closure, or atrophic closure. To evaluate foveal retinal function, scanning laser ophthalmoscope (SLO) microperimetry was performed preoperatively and 6 months postoperatively. RESULTS: Postoperatively in 18 eyes (64%), the foveal images became normal or almost normal and were classified as having complete closure, 6 eyes (21%) were classified as having partial closure, and 4 eyes (14%) as having atrophic closure. The corresponding visual acuity levels 6 months postoperatively were, respectively, 0.10, 0.35, and 0.64 (P<.01) based on LogMAR analysis. Preoperative SLO microperimetry detected an absolute scotoma at the bottom of all macular holes; postoperatively, the absolute scotoma disappeared in the 18 eyes with complete hole closure, but a relative scotoma was detected in 6 eyes. Of 6 eyes with partial closure, 1 had an absolute scotoma and 5 had a relative scotoma. An absolute scotoma was detected in 4 eyes with atrophic closure. CONCLUSIONS: After macular hole closure, SLO findings correlate both with biomicroscopic findings and foveal function. Better anatomical foveal recovery in eyes after macular hole closure results in better improvement of vision than in eyes in which the foveal anatomical findings are not as good.

Aged↗
PubMed2000

Initial presentation with stage IV colorectal cancer: how aggressive should we be?

HYPOTHESIS: The appropriate surgical treatment of patients with colorectal cancer who are found on initial presentation to have stage IV disease is controversial. With presumed limited life expectancy, the role of primary colon or rectal resection has been questioned, as has the utility of synchronous hepatic resection. DESIGN: A retrospective chart review. SETTING: The University of Chicago Hospitals, Chicago, Ill, a tertiary-care referral center. PATIENTS: One hundred twenty patients were identified through The University of Chicago Hospitals Tumor Registry whose initial presentation showed stage IV colorectal cancer and who underwent laparotomy. MAIN OUTCOME MEASURES: The primary end points of the study were perioperative morbidity and mortality and overall survival. RESULTS: Median survival and 5-year survival were 14.4 months and 10%, respectively. Survival was greater for patients younger than 65 years than for those who were aged 65 years or older (18.3 vs 9.8 months; P = .007). Carcinomatosis was associated with significantly decreased survival when compared with less extensive stage IV disease (6.7 vs 18.1 months; P<.001). Patients who underwent any form of resection of hepatic metastases achieved a survival advantage over those with unresectable liver lesions (median survival, 29.6 vs 10.2 months; P<.001). Overall, 27 patients (22.5%) developed postoperative complications. Seven patients (5.8%) died during the postoperative period. CONCLUSIONS: Age of 65 years or older, carcinomatosis, and extensive (bilobar) liver involvement are associated with decreased survival and increased postoperative morbidity and mortality and may negate any potential benefit patients derive from resection of the primary lesion. A substantial number of patients with synchronous hepatic metastases have protracted survival that justifies resection of the primary colorectal tumor at initial presentation. Despite the presence of stage IV disease, resection of the primary tumor and, when feasible, liver metastases is indicated.

Adult↗
PubMed2000

A malignant rhabdoid tumor of the kidney occurring concurrently with a brain tumor: report of a case.

Malignant rhabdoid tumor of the kidney (MRTK) is one of the most lethal neoplasms to occur in young infants. Cases of MRTK accompanying an embryonal tumor in the central nervous system have occasionally been described. We present herein an interesting case of MRTK that was clinically diagnosed preoperatively. A male infant aged 6 months with both a midline brain tumor and a renal neoplasm was transferred to our institution. Although roentgenographic evaluation suggested that the renal lesion was a Wilms' tumor, midkine (MK), a growth and differentiation factor characteristically present in the urine of patients with Wilms' tumor, was not detected. A preoperative diagnosis of MRTK was established based on the lack of urinary MK in addition to the typical clinical features of the young age and the concurrent brain tumor.

Brain Neoplasms↗
PubMed2000

Predicting incomplete uterine rupture with vaginal sonography during the late second trimester in women with prior cesarean.

OBJECTIVE: To evaluate the usefulness of serial transvaginal ultrasonographic measurement of the thickness of the lower uterine segment in the late second trimester for predicting the risk of intrapartum incomplete uterine rupture in women with previous cesarean delivery. METHODS: Serial transvaginal ultrasonography with full bladder was performed in 374 women without previous cesarean delivery (control group) and 348 women with previous cesarean delivery (cesarean group) from 19 to 39 weeks' gestation. The thickness of the lower uterine segment was measured in the longitudinal plane of the cervical canal. RESULTS: The thickness of the lower uterine segment decreased from 6.7 +/- 2.4 mm (mean +/- standard deviation [SD]) at 19 weeks' gestation to 3.0 +/- 0.7 mm at 39 weeks' gestation in the control group, but the thickness was more than 2.0 mm throughout this period in each control subject. In the cesarean group, the thickness decreased from 6.8 +/- 2.3 mm at 19 weeks' to 2.1 +/- 0.7 mm at 39 weeks' gestation and was significantly thinner than that of the control group after 27 weeks' gestation (P <.05). Eleven of 12 women (91%) with lower uterine segment less than the mean control - 1 SD in the late second trimester had a very thin lower uterine segment at cesarean delivery with fetal hair being visible through the amniotic membrane, ie, incomplete uterine rupture. In 17 of 23 women (74%) with lower uterine segment less than 2.0 mm in thickness within 1 week (4 +/- 3 days) before repeat cesarean delivery, intrapartum incomplete uterine rupture developed. CONCLUSION: Transvaginal ultrasonography is useful for measurement of the uterine wall after previous cesarean delivery.

Adult↗
PubMed2000

Precise measurements of the gamma-ray emission probabilities of 186Re and 188Re.

Gamma-ray emission probabilities of 186Re and 188Re are important in nuclear medicine, and have been precisely measured by 4pibeta-gamma coincidence using a live-timed two-dimensional data-acquisition system. The gamma-ray emission probabilities of the 137.2 keV for 186Re and 155.1 keV for 188Re were 0.09487+/-0.00029 and 0.15425+/-0.00072, respectively.

Gamma Rays↗
PubMed2000

The role of the cleavage site 2'-hydroxyl in the Tetrahymena group I ribozyme reaction.

BACKGROUND: The 2'-hydroxyl of U preceding the cleavage site, U(-1), in the Tetrahymena ribozyme reaction contributes 10(3)-fold to catalysis relative to a 2'-hydrogen atom. Previously proposed models for the catalytic role of this 2'-OH involve coordination of a catalytic metal ion and hydrogen-bond donation to the 3'-bridging oxygen. An additional model, hydrogen-bond donation by the 2'-OH to a nonbridging reactive phosphoryl oxygen, is also consistent with previous results. We have tested these models using atomic-level substrate modifications and kinetic and thermodynamic analyses. RESULTS: Replacing the 2'-OH with -NH(3)(+) increases the reaction rate approximately 60-fold, despite the absence of lone-pair electrons on the 2'-NH(3)(+) group to coordinate a metal ion. Binding and reaction of a modified oligonucleotide substrate with 2'-NH(2) at U(-1) are unaffected by soft-metal ions. These results suggest that the 2'-OH of U(-1) does not interact with a metal ion. The contribution of the 2'-moiety of U(-1) is unperturbed by thio substitution at either of the nonbridging oxygens of the reactive phosphoryl group, providing no indication of a hydrogen bond between the 2'-OH and the nonbridging phosphoryl oxygens. In contrast, the 10(3)-fold catalytic advantage of 2'-OH relative to 2'-H is eliminated when the 3'-bridging oxygen is replaced by sulfur. As sulfur is a weaker hydrogen-bond acceptor than oxygen, this effect suggests a hydrogen-bonding interaction between the 2'-OH and the 3'-bridging oxygen. CONCLUSIONS: These results provide the first experimental support for the model in which the 2'-OH of U(-1) donates a hydrogen bond to the neighboring 3'-bridging oxygen, thereby stabilizing the developing negative charge on the 3'-oxygen in the transition state.

Animals↗
PubMed2000

The H9/M8166 tropism of various HIV-1 mutants is determined by distinct cellular factors (review).

We have previously shown that a number of human immunodeficiency virus type 1 (HIV-1) mutants generated in vitro display a replication-defect in a cell-dependent manner. Of the mutants of this category, those of gag, vif, and env mutants do not grow at all in lymphocytic H9 (non-permissive) cells, but quite well in M8166 (permissive) cells. To determine whether the cell-dependent growth of the mutants is functionally related to each other, a number of double mutants were constructed, and monitored for their replication and biochemical property in various cells. The results obtained have indicated that there are multiple cellular factors responsible for the growth phenotype. Together with our previous findings on the host cell-dependent mutants of HIV-1, it is concluded that number of distinct cellular factors are involved in the various steps in HIV-1 replication cycle.

Animals↗
PubMed2000

Torsade de pointes associated with hypokalemia after anthracycline treatment in a patient with acute lymphocytic leukemia.

Severe dose-dependent anthracycline cardiotoxicity is reported to cause myocardial damage resulting in congestive heart failure. However, torsade de pointes, a life-threatening arrhythmia caused by chronic anthracycline cardiotoxicity, has not been reported previously. A 16-year-old girl who developed torsade de pointes after 6 months of chemotherapy for acute lymphocytic leukemia (French-American-British classification L2) is described. When the patient was readmitted to the hospital because of syncope, peripheral blood and bone marrow analysis indicated a relapse. In addition, the patient was hypokalemic. Twenty-four-hour ambulatory electrocardiographic monitoring demonstrated QT prolongation and an episode of torsade de pointes. The electrocardiographic changes and arrhythmia improved after correction of the hypokalemia. An inverse correlation between leukocyte count and hypokalemia was observed. The patient died from pulmonary hemorrhage. Autopsy examination demonstrated myocardial degeneration consistent with damage induced by antineoplastic antibiotics. The cumulative dose of anthracycline and anthraquinone was less than the conventional dose limit associated with chronic cardiotoxicity, even for children who are more sensitive to anthracyclines. Torsade de pointes can occur in the setting of chronic anthracycline cardiotoxicity. Therefore, children or young adults who are more sensitive to anthracycline need careful observation that includes electrolyte monitoring, especially for potassium.

Adolescent↗
PubMed2000

[Therapeutic effect and clinical findings in patients with MPO-ANCA associated vasculitis syndrome].

We investigated to clarify the clinical findings, course and therapeutic effect in the patients with MPO (myeloperoxidase)-ANCA (anti-neutrophil cytoplasmic antibody) associated vasculitis syndrome. We analyzed clinical findings and data of 19 cases of MPO-ANCA associated vasculitis. These patients were diagnosed with clinical symptoms (fever, arthralgia, body weight loss, etc.), laboratory data (high titer of CRP, leukocytosis, thrombocytosis, and high titer of MPO-ANCA) and pathologic findings of necrotizing vasculitis. They were 14 male and 5 female aged 18 to 84 years (mean 65 years) and were treated with prednisolone and immunosuppressive agents, and additional therapy included pulse therapy and plasma exchange. Seven cases were dead within 3 months. Post-mortum examination showed that these cases died of pneumonitis, cerebral events and gastric bleeding. There was no mortal case induced by over-immunosuppression. In survival cases, the MPO-ANCA levels decreased rapidly after these therapies and these antibodies were maintained low levels (360 to 25 EU/l). Comparison of fatal cases and survival cases, there were difference in the initial dose of prednisolone (27 mg/day vs. 56 mg/day), the ratio of double filtration plasmapheresis (14% vs. 42%), and the ratio of immunosuppressive therapy (14% vs. 83%). The measurement of MPO-ANCA is useful makers of the diagnosis and effectiveness of the therapy in patients with MPO-ANCA associated vasculitis. We recommend the aggressive therapy, including prednisolone, immunosuppressive agents and plasma exchange for MPO-ANCA associated vasculitis. We believe that the aggressive therapy improve the survival rate of the patients with MPO-ANCA associated vasculitis.

Adolescent↗
PubMed2000

Intravitreal injection of hyaluronidase cannot induce posterior vitreous detachment in the rabbit.

PURPOSE: To investigate whether intravitreal injection of hyaluronidase can induce posterior vitreous detachment (PVD) in the rabbit. METHODS: One eye each of 12 New Zealand white rabbits received intravitreal injection via the pars plana of 20 IU of hyaluronidase (0.1 mL reconstituted in sterile balanced salt solution [BSS]) into the midvitreous cavity. The fellow eye of each rabbit received a vitreous injection of 0.1 mL of BSS. At 3 and 6 months after intravitreal injection, four and eight rabbits were killed, respectively, and the eyes were enucleated. After fixation, scanning electron microscopy was performed to study the vitreoretinal interface. RESULTS: At 3 and 6 months after injection, scanning electron microscopy showed that the retinal surfaces in eyes that received either hyaluronidase or BSS were covered with vitreous collagen fibers. No eyes, even those that received hyaluronidase over a period of 6 months, had the smooth retinal surface consistent with a bare internal limiting lamina that suggests the development of PVD. CONCLUSION: Hyaluronidase cannot induce PVD in the rabbit over a 6-month period after vitreous injection.

Animals↗
PubMed1999

Distribution pattern of inhibitory and excitatory synapses in the dendritic tree of single masseter alpha-motoneurons in the cat.

Little is known about the differences in the distributions of inhibitory and excitatory synapses in the dendritic tree of single motoneurons in the brainstem and spinal cord. In this study, the distribution of gamma-aminobutyric acid (GABA)-, glycine-, and glutamate-like immunoreactivity in axon terminals on dendrites of cat masseter alpha-motoneurons, stained intracellularly with horseradish peroxidase, was examined by using postembedding immunogold histochemistry in serial ultrathin sections. The dendritic tree was divided into three segments: primary (Pd) and distal (Dd) dendrites and intermediate (Id) dendrites between the two segments. Quantitative analysis of 175, 279, and 105 boutons synapsing on 13 Pd, 54 Id, and 81 Dd, respectively, was performed. Fifty percent of the total number of studied boutons were immunopositive for GABA and/or glycine and 48% for glutamate. Among the former, 27% showed glycine immunoreactivity only and 14% were immunoreactive to both glycine and GABA. The remainder (9%) showed immunoreactivity for GABA only. As few as 3% of the boutons were immunonegative for the three amino acids. Most boutons immunoreactive to inhibitory amino acid(s) contained a mixture of spherical, oval, and flattened synaptic vesicles. Most boutons immunoreactive to excitatory amino acid contained clear, spherical, synaptic vesicles with a few dense-cored vesicles. When comparisons of the inhibitory and excitatory boutons were made between the three dendritic segments, the proportion of the inhibitory to the excitatory boutons was high in the Pd (60% vs. 37%) but somewhat low in the Id (46% vs. 52%) and Dd (44% vs. 53%). The percentage of synaptic covering and packing density of the inhibitory synaptic boutons decreased in the order Pd, Id, and Dd, but this trend was not applicable to the excitatory boutons. The present study provides possible evidence that the spatial distribution patterns of inhibitory and excitatory synapses are different in the dendritic tree of jaw-closing alpha-motoneurons.

Animals↗