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Biomedical subjects

S Koizumi

Publications and source records attributed to S Koizumi.

At least 55 records · Page 3Linked to original sources
PubMed2000

Congenital ureteral diverticulum coexistent with hydronephrosis caused by vascular compression involving the uterine artery and umbilical ligament: report of a case.

Coexistence of congenital ureteral diverticulum and hydronephrosis caused by vascular compression is a rare entity. The authors experienced a case of congenital ureteral diverticulum coexistent with hydronephrosis caused by aberrant vascular compression by uterine and umbilical arteries in a 14-year-old girl. The authors could not diagnose accurately this abnormality preoperatively by 3-dimensional computed tomography. After partial ureterectomy, including resection of the saccular lesion and ureteroneocystostomy, the frequency of urinary tract infection decreased.

Adolescent↗
PubMed2000

Cloning and expression of beta1,4-galactosyltransferase gene from Helicobacter pylori.

Helicobacter pylori, which is a human pathogen associated with gastric and duodenal ulcer, has been shown to express human oncofetal antigens Lewis X and Lewis Y. Although the mammalian glycosyltransferases that synthesize these structures are well characterized, little is known about the corresponding bacterial enzymes. We report that a novel beta1,4-galactosyltransferase gene (HpgalT) involved in the biosynthesis of lipopolysaccharides in H. pylori has been cloned and expressed in Escherichia coli. The deduced amino acid sequence of the protein (HpGal-T) encoded by HpgalT consists of 274 residues with the calculated molecular mass of 31,731 Da, which does not show significant similarity to those of beta1,4-galactosyltransferases from mammalian sources and Neisseria It was confirmed that HpGal-T catalyzed the introduction of galactose from UDP-Gal in a beta1,4 linkage to accepting N-acetylglucosamine (GlcNAc) residues by means of high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). When the E.coli cells which overexpressed HpgalT was coupled with the UDP-Gal production system, which consisted of recombinant E.coli cells overexpressing its UDP-Gal biosynthetic genes and Corynebacterium ammoniagenes, N-acetyllactosamine, a core structure of lipopolysaccharide of H.pylori, was efficiently produced from orotic acid, galactose, and GlcNAc.

Amino Acid Sequence↗
PubMed2000

Feasibility study of autologous peripheral blood stem cell transplantation for the treatment of childhood acute myelogenous leukemia.

BACKGROUND: The primary object of this study was to identify treatment-related variables that may predict relapse of acute myelogenous leukemia (AML) after autologous peripheral blood stem cell transplantation (PBSCT), which will be critical for the development of a suitable protocol for wider application. METHODS: A total of 28 children (age 0-18 years) with AML underwent PBSCT and have had a minimum follow-up of 25 months; including 24 patients in their first complete remission (CR) and four in their second CR. The patients were divided into two cohorts according to the study phase: 16 patients were treated in an early phase pilot study and 12 patients in their first CR were treated in a prospective trial. Fifteen of the first-CR patients had any of the cited high-risk features of high WBC count (>100x10(9)/l; n = 5), FAB M0/M4/M5/M7 subtypes (n = 11) or delayed achievement of CR (n = 9). Except in one patient, cytoreductive regimens did not include total body irradiation (TBI). RESULTS: After PBSCT, one patient died of veno-occulsive disease (VOD) and another patient relapsed early on day 43, but the remaining patients showed engraftment. Leukemic relapse was observed 1-29 months after PBSCT (median, 8 months); in all of the 4 children treated in their second CR and in 11 of the 24 patients (46%) treated in their first CR. The remaining patients have been disease-free for 24 to 97 months (median, 53 months). Using a multivariate analysis, the timing of apheresis was the most significant prognostic factor for those treated in their first CR (p = 0.03); 12 of the 16 patients whose PBSC were collected beyond 2.5 months of CR continue to remain in CR, while seven of the eight patients whose PBSC were harvested within 2.5 months of CR relapsed. CONCLUSION: Although the small number of patients studied does not allow firm conclusions to be drawn regarding the relative effectiveness of this therapy, the results do suggest the feasibility of further studies of PBSCT for the treatment of childhood AML with high-risk features including the assessment of minimum residual disease.

Adolescent↗
PubMed2000

Morphological characterization of bicontinuous structures in polymer blends and microemulsions by the inverse-clipping method in the context of the clipped-random-wave model.

A method is proposed to determine the spectral function of the clipped-random-wave (CRW) model directly from scattering data. The spectral function f(k) (k is a wave number) gives the distribution of the magnitude of wave vectors of the sinusoidal waves that describes the essential features of the two-phase morphology. The proposed method involves "inverse clipping" of a correlation function to obtain f(k) and does not require any a priori assumptions for f(k). A critical test of the applicability of the inverse-clipping method was carried out by using three-component bicontinuous microemulsions. The method was then used to determine f(k) of the bicontinuous structure of a phase-separating polymer blend. f(k) for the polymer blend turned out to be a multipeaked function, while f(k) for the microemulsions exhibits a single broad maximum representing periodicity of the morphology. These results indicate the presence of the long-range regularity in the morphology of the polymer blend. Three-dimensional (3D) morphology corresponding to the scattering data of the polymer blend was generated using the CRW model together with the multipeaked f(k). Interface curvatures of the 3D morphology calculated from f(k) were measured and compared with those experimentally determined directly from the laser scanning confocal microscopy in the same blend.

Journal Article↗
PubMed2000

[ATP receptors in pain].

Extracellular ATP has been known to activate sensory neurons via the ATP-gated ion channels P2X receptors, leading to the proposal that the P2X receptors may play a role in signal transduction of pain from the peripheral site to the spinal cord in vivo. P2X3 receptors are expressed in capsaicin-sensitive small-sized dorsal root ganglion (DRG) neurons, and they are involved in the generation of rapidly desensitizing inward current and evoking nocifensive behavior and thermal hyperalgesia. Heteromeric P2X2/3 (P2X2 and P2X3) receptor is expressed in capsaicin-insensitive primary afferent fibers, and its activation leads to the generation of slow desensitizing currents and induction of mechanical allodynia. In addition, accumulating information suggests the involvement of G protein-coupled ATP receptors in the modulation of the generation and transmission of pain.

Adenosine Triphosphate↗
PubMed2000

Inhibitory effects of heavy metals on transcription factor Sp1.

Heavy metals are expected to affect the biological activity of various metal-containing proteins, including transcriptional regulators. We studied the effects of several heavy metal ions on the DNA-binding activity of a Zn-finger transcription factor, Sp1. With respect to both DNA elements through which Sp1 acts positively and negatively, Cd2+ inhibited DNA-binding of Sp1 at 20 microM or higher, while the toxic effect of Zn2+ was obvious only at more than 200 microM. Inhibition was also apparent for Cu2+ but less remarkable for Hg2+. The inhibition by Cd2+ was relieved by the addition of Zn2+ at much lower concentrations than that of Cd2+. These results suggest that the toxic potential of heavy metals could be largely influenced by the intracellular Zn2+ concentration.

Dose-Response Relationship, Drug↗
PubMed2000

Individual metal responsive elements of the human metallothionein-IIA gene independently mediate responses to various heavy metal signals.

Metallothioneins (MTs) are small metal-binding proteins that have a role in the defense against heavy metals. Mammalian MT genes are transcriptionally activated by metals such as Cd and Zn through multiple copies of the metal responsive element (MRE) present in the 5'-flanking region. To examine whether each MRE in a single promoter has a distinct role, we characterized seven MREs located upstream of the human MT-IIA gene. By transient transfection experiments using MRE-driven reporter gene constructs, individual MREs were assayed for the activity to mediate transcription in response to several heavy metal species. Four MREs including MREs a, b, e and g independently mediated reporter gene expression in response to Zn, Cd and Hg, while other MREs were not responsive to any of these metals. These results suggest that the multiplicity of MRE contributes to enhancing its activity, rather than providing functional diversity.

DNA-Binding Proteins↗
PubMed2000

[Segmental infarction of testicle presenting as right acute scrotum: a case report].

We report a case of segmental infarction of a testicle seen in a 28-year-old man with right lower abdominal pain who visited our hospital. On physical examination, the right testicle was slightly elevated and Prehn's sign was positive. As torsion of the right spermatic cord was suspected, ultrasonography and color Doppler sonography were performed, revealing sufficient blood supply in the right spermatic cord and in the most part of the right testicle. However, a low echogenic area without blood flow was noted in the upper pole of testicle. Since CT and MRI findings couldn't rule out a testicular tumor, right high orchiectomy was performed. The specimen revealed a hemorrhagic area, histologically proved to be segmental hemorrhagic infarction of the testicle. Segmental infarction of a testicle is rare and our case is the 31st case in the world literature (the 7th case in Japan).

Acute Disease↗
PubMed2000

[Ineffective and recurrent cases of thoracoscopic sympathectomy for hyperhidrosis and intractable pain].

We reported the cases of thoracoscopic sympathectomy, that is, six cases of hyperhidrosis, three of post herpetic neuralgia, and four of reflex sympathetic dystrophy, including recurrent or incompletely resected or ineffective ones. Recently this procedure for hyperhidrosis had been performed frequently because of its effectiveness, less pain, early discharge and cosmetic aspect. For an ineffective case of hyperhidrosis abdominal respiration which emphasized the exhalation and using an upper abdomen decreased the sweating. The balance of autonomic nerve system, toward parasympathetic dominant, was thought to be improved by conscious respiration. The decrease of sweating right after the operation in a case of incomplete resection indicated that intraoperative maneuver could restrict the sympathetic nerve. This procedure for a pain control could be less effective than that for hyperhidrosis, so an adequate preoperative informed consent was thought to be necessary.

Adolescent↗
PubMed2000

[Liposarcoma of the spermatic cord in the left scrotum and inguinal region: a case report].

We report a rare case of liposarcoma of the spermatic cord in the left scrotum and inguinal region. The patient was a 75 year old male, who visited our hospital with the complaint of painless left scrotal swelling and inguinal mass which had been noticed for 3 to 4 years. Ultrasonography and computed tomography (CT) showed a heterogenous mass in the left inguinal region and intrascrotum. We suspected a left testicular tumor and removed it by high inguinal orchiectomy. Histological examination revealed a well-differentiated liposarcoma of sclerosing type. Tumor local recurrence was not recognized at 8 months after operation. This is the 43rd case of liposarcoma of the spermatic cord in the Japanese literature.

Aged↗
PubMed2000

Limited distribution of new quinolone antibacterial agents into brain caused by multiple efflux transporters at the blood-brain barrier.

Transport of new quinolone antibacterial agents (quinolones) at the blood-brain barrier (BBB) was studied in vitro by using immortalized rat brain capillary endothelial cells RBEC1, and in vivo by using the brain perfusion method in rats and multidrug-resistant mdr1a/1b gene-deficient mice. The permeability coefficient of grepafloxacin measured by brain perfusion was increased by an excess of unlabeled grepafloxacin, suggesting a participation of a saturable BBB efflux system. Uptake coefficients of [(14)C]grepafloxacin, [(14)C]sparfloxacin, and [(14)C]levofloxacin by RBEC1 cells at the steady state were increased in the presence of the unlabeled quinolones. The steady-state uptake of [(14)C]grepafloxacin was increased in the presence of various quinolones. Brain distributions of [(14)C]grepafloxacin and [(14)C]sparfloxacin evaluated in terms of the brain-to-plasma free concentration ratio in mdr1a/1b gene-deficient mice were significantly higher than those in wild-type mice, demonstrating an involvement of P-glycoprotein as the efflux transporter. Anionic compounds, including 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and genistein, increased the steady-state uptake of [(14)C]grepafloxacin by RBEC1 cells. Because [(14)C]grepafloxacin was transported by multidrug resistance-associated protein (MRP), in MRP1-overexpressing cells and because RBEC1 and primary cultured brain capillary endothelial cells expressed MRP1, this protein may be an additional efflux transporter for quinolones. Furthermore, the permeability coefficient of [(14)C]grepafloxacin across the BBB was increased by DIDS or in the absence of bicarbonate ions in the brain perfusion method. DIDS or bicarbonate ion did not affect MRP1 function. Accordingly, the brain distribution of quinolones is restricted by the action of multiple efflux transporters, including P-glycoprotein, MRP1, and an unknown anion exchange transporter.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2000

[Treatment and prognosis of children with relapsed non-Hodgkin's lymphoma--a report from CCLSG-NHL 890 Study. Children's Cancer and Leukemia Study Group (CCLSG)].

To address the issue of salvageability in relapsed children with NHL who had all received the same frontline therapy, we retrospectively studied the treatment response and the outcome of 27 children who relapsed following the CCLSG-NHL890 protocol. The reinduction rates and 3-year survival rates (mean +/- SD) were as follows: lymphoblastic lymphoma (LB, n = 9), 44% & 17 +/- 14%; leukemia lymphoma syndrome (LLS, n = 8), 25% & 0%; large cell lymphoma (LC, n = 3) 100% & 67 +/- 27%; Burkitt's lymphoma (B, n = 7) 0% & 0%. Thus, the salvageability of LC lymphoma was good, but the outcome of Burkitt's lymphoma was very poor. CCLSG-NHL960 protocol for LB lymphomas and intensive multiagent regimens for LC lymphomas produced favorable response rates, but the effect of the high-dose Ara-C regimen for Burkitt's lymphoma was not determined. The initial stages of the disease seemed to be associated with the patient outcome: the outcome of the patients in stage IV was inferior to that of patients in stages II or III. Other clinical variables, such as relapse sites, relapse time and BM rescue did not affect the patients' outcome.

Adolescent↗
PubMed1999

Regulation of ryanodine receptor opening by lumenal Ca(2+) underlies quantal Ca(2+) release in PC12 cells.

Graded or "quantal" Ca(2+) release from intracellular stores has been observed in various cell types following activation of either ryanodine receptors (RyR) or inositol 1,4,5-trisphosphate receptors (InsP(3)R). The mechanism causing the release of Ca(2+) stores in direct proportion to the strength of stimulation is unresolved. We investigated the properties of quantal Ca(2+) release evoked by activation of RyR in PC12 cells, and in particular whether the sensitivity of RyR to the agonist caffeine was altered by lumenal Ca(2+). Quantal Ca(2+) release was observed in cells stimulated with 1 to 40 mM caffeine, a range of caffeine concentrations giving a >10-fold change in lumenal Ca(2+) content. The Ca(2+) load of the caffeine-sensitive stores was modulated by allowing them to refill for varying times after complete discharge with maximal caffeine, or by depolarizing the cells with K(+) to enhance their normal steady-state loading. The threshold for RyR activation was sensitized approximately 10-fold as the Ca(2+) load increased from a minimal to a maximal loading. In addition, the fraction of Ca(2+) released by low caffeine concentrations increased. Our data suggest that RyR are sensitive to lumenal Ca(2+) over the full range of Ca(2+) loads that can be achieved in an intact PC12 cell, and that changes in RyR sensitivity may be responsible for the termination of Ca(2+) release underlying the quantal effect.

Animals↗
PubMed1999

Automatic border detection identifies subclinical anthracycline cardiotoxicity in children with malignancy.

BACKGROUND: Anthracycline drugs for cancer therapy often cause functional myocardial impairment even in relatively low doses. We investigated the left ventricular function in asymptomatic anthracycline-treated children by automatic border detection (ABD) to assess its clinical usefulness for unmasking latent anthracycline-induced myocardial damage. METHODS AND RESULTS: Thirty-four children (0.7 to 17.6 years old) during or after anthracycline chemotherapy (26 to 1100 mg/m2) for malignancy (Chemo group) were studied, and 40 children (2.8 to 15.6 years old) without cardiac involvement served as normal control subjects (Control group). All patients underwent complete echocardiographic examination, including M-mode, Doppler, and ABD. Conventional echocardiography disclosed no difference between groups with regard to ejection fraction and the ratio of early to late transmitral flow velocity. In marked contrast, an investigation using ABD revealed that the Chemo group appeared to have some anthracycline-induced myocardial damage. In the apical 4-chamber view, peak filling rate in the Chemo group [2.3+/-0.4 end-diastolic area (EDA)/s] was significantly lower than that in the Control group (3.1+/-0.5 EDA/s) (P<0.0001), and time to peak filling rate in the Chemo group (106+/-31 ms) was clearly prolonged compared with that in the Control group (74+/-22 ms) (P<0.0001). CONCLUSIONS: Echocardiographic ABD may be a sensitive and useful noninvasive approach for evaluating subclinical anthracycline cardiotoxicity.

Adolescent↗
PubMed1999

Large-scale production of N-acetyllactosamine through bacterial coupling.

A large-scale production system of N-acetyllactosamine, a core structure of various oligosaccharides, was established by a whole-cell reaction through the combination of recombinant Escherichia coli strains and Corynebacterium ammoniagenes. Two recombinant E. coli strains over-expressed the UDP-Gal biosynthetic genes and the beta-(1-->4)-galactosyltransferase gene of Neisseria gonorrhoeae, respectively. C. ammoniagenes contributed the production of UTP from orotic acid. N-Acetyllactosamine was accumulated at 279 mM (107 g L-1) after a 38 h reaction (2.5 L in volume) starting from orotic acid, D-galactose, and 2-acetamido-2-deoxy-D-glucose.

Acetylglucosamine↗
PubMed1999

Membrane-type matrix metalloproteinase-1 expression and activation of gelatinase A as prognostic markers in advanced pediatric neuroblastoma.

BACKGROUND: Recently a novel membrane-type matrix metalloproteinase-1 (MT-MMP-1) was discovered to be a specific activator of progelatinase A, and was correlated with tumor invasion. To the authors' knowledge, no information regarding the expression of MT-MMP-1 has been reported in childhood malignancies. In this study, the authors attempted to elucidate the specific mechanisms that underlay the invasive behavior of neuroblastoma (NB) cells with respect to the expression of MT-MMP-1 and its determined prognostic value, especially in pediatric patients with advanced Evans' Stage IV NB. METHODS: Thirty specimens from surgically excised NB (mainly Stage IV) were collected retrospectively. The total levels of progelatinase A (68 kilodaltons [kD]) and its activated form (62 kD) in the tumor lysates were quantified by gelatin zymography. The expression of MT-MMP-1 was estimated by immunostaining with a monoclonal antibody (113-5B7). RESULTS: Progelatinase A and the activated form were detected in each of the 30 specimens. The gelatinase A activation ratio, 62 kD/(62 kD + 68 kD), strongly correlated with the high levels of MT-MMP-1 expression found in specimens of advanced tumor stage. In the patients with advanced Stage IV NB, the activation ratio was strongly associated with unfavorable clinical outcome; the 5-year survival was 88.9% in the patients with a low activation ratio (< or = 26%) versus only 21.2% in the patients with a high activation ratio (>26%). CONCLUSIONS: Gelatinase A activation correlates with high expression of MT-MMP-1 on NB cells and is associated strongly with advanced stage and poor clinical outcome. These results are consistent with the notion that MT-MMP-1 expression is an important prognostic determinant of the biologic behavior of NB.

Adolescent↗
PubMed1999

Improvement in CNS protective treatment in non-high-risk childhood acute lymphoblastic leukemia: report from the Japanese Children's Cancer and Leukemia Study Group.

BACKGROUND: Prevention of central nervous system (CNS) leukemia by early introduction of therapy to this sanctuary site is an essential component of modern treatment strategy for acute lymphoblastic leukemia (ALL). However, the optimal form of preventive CNS therapy remains debatable. PROCEDURE: To address this issue, we evaluated the efficacy of CNS preventive therapy for 572 children with ALL who achieved complete remission in the Children's Cancer and Leukemia Study Group (CCLSG) ALL874 (1987-1990) and ALL911 (1991-1993) studies. They received risk-directed therapy based on age and leukocyte count. In the ALL 874 study, the non-high-risk (low-risk [LR] + intermediate risk [IR]) patients were randomly assigned to the conventional cranial irradiation (CRT) regimen (L874A and I874A) and the high-dose methotrexate (HDMTX) regimen without CRT (L874B and I874B). The former patients received 18-Gy CRT plus 3 doses of intrathecal (i.t.) MTX and the latter patients received 3 courses of HDMTX at 2 g/m2 plus 13 doses of ITMTX (L874B) or 4 courses of HDMTX at 4.5 g/m2 plus 1 dose of ITMTX (I874B). RESULTS: The 7-year probabilities (+/- SE) of CNS relapse-free survival were 97.3% +/- 2.6% (L874A, n = 41) vs. 90.3% +/- 5.3% (L874B, n = 39) (P = 0.25) in the LR patients, and 100% (I874A, n = 55) vs. 78.5% +/- 6.5% (I874B, n = 54) (P = 0.002) in the IR patients. The corresponding disease-free survival (DFS) rates were 79.4% +/- 6.5% vs. 74.4% +/- 7.3% (P = 0.62) in the LR group and 63.3% +/- 6.8% vs. 58.3% +/- 7.2% (P = 0.66) in the IR group. Thus, the HDMTX regimen could not provide better protection of CNS relapse as compared with the CRT regimen, although their overall efficacy was not significantly different. In the ALL 911 study, intensive systemic chemotherapy with extended i,t, injections of MTX plus cytarabine achieved a high CNS relapse-free survival (98% +/- 1.9% at 7 years) and a favorable DFS (85.5% +/- 5% at 7 years) in the IR patients. The patients in the high-risk (HR) group in both ALL874 and ALL911 studies received the 18-Gy or 24-Gy CRT with intensive systemic chemotherapy. Their 7-year probabilities of CNS relapse-free survival ranged from 88% to 95%, among which the T-ALL patients had a risk of CNS leukemia, which was 3-4 times higher compared with B-precursor ALL patients. CONCLUSIONS: These results indicate that long-term intrathecal CNS prophylaxis as well as appropriate systemic therapy for the non-high-risk patients can provide protection against CNS relapse equivalent to that provided by cranial irradiation.

Adolescent↗