Search PubMed⌕ Search

Biomedical subjects

K Ito

Publications and source records attributed to K Ito.

At least 181 records · Page 10Linked to original sources
PubMed2001

Oral absorption of cephalosporins is quantitatively predicted from in vitro uptake into intestinal brush border membrane vesicles.

In order to establish a method to predict oral absorption of drugs, which are absorbed by the oligopeptide transporter (PepT1), fraction absorbed (F) of cephalosporin antibiotics was predicted from in vitro uptake into rat intestinal brush border membrane vesicles (BBMV). Using in vitro uptake data, F values of cephalosporins in humans were predicted using the equation derived from the complete radial mixing (CRM) model, which was proposed by Amidon et al. (Amidon et al., J. Pharm. Sci. 69 (1980) 1369). In the present study, uptake into BBMV was measured at 25 and 4 degrees C in the presence of an H+ -gradient, and the uptake clearance (CLuptake) was calculated. Clearance for the uptake mediated by PepT1 (DeltaCLuptake) was then calculated as CLuptake at 25 degrees C minus that at 4 degrees C. When DeltaCLuptake and F values were analyzed according to the present equation, fairly good correlation between DeltaCLuptake and F was observed. It was further demonstrated that the present method may be able to quantitatively predict F values of cephalosporins by using several cephalosporins as standards.

Absorption↗
PubMed2001

Transport of the beta -O-glucuronide conjugate of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) by the multidrug resistance protein 1 (MRP1). Requirement for glutathione or a non-sulfur-containing analog.

Nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) play a crucial role in the induction of lung cancer, and NNAL-O-glucuronide formation and elimination are important steps in detoxification of these compounds. In the present study, we investigated the ATP-binding cassette (ABC) protein, MRP1 (ABCC1), as a candidate transporter responsible for NNAL-O-glucuronide export. MRP1 mediates the active transport of numerous GSH-, sulfate-, and glucuronide-conjugated organic anions and can transport certain xenobiotics by a mechanism that may involve co-transport with GSH. Using membrane vesicles prepared from transfected cells, we found that MRP1 transports [3H]NNAL-O-glucuronide but is dependent on the presence of GSH (Km 39 microm, Vmax 48 pmol x mg(-1) x min(-1)). We also found that the sulfur atom in GSH was dispensable because transport was supported by the GSH analog, gamma-glutamyl-alpha-aminobutyryl-glycine. Despite stimulation of NNAL-O-glucuronide transport by GSH, there was no detectable reciprocal stimulation of [3H]GSH transport. Moreover, whereas the MRP1 substrates leukotriene C4 (LTC4) and 17beta-estradiol 17beta-(d-glucuronide) (E(2)17betaG) inhibited GSH-dependent uptake of [3H]NNAL-O-glucuronide, only [3H]LTC4 transport was inhibited by NNAL-O-glucuronide (+GSH) and the kinetics of inhibition were complex. A mutant form of MRP1, which transports LTC4 but not E(2)17betaG, also did not transport NNAL-O-glucuronide suggesting a commonality in the binding elements for these two glucuronidated substrates, despite their lack of reciprocal transport inhibition. Finally, the related MRP2 transported NNAL-O-glucuronide with higher efficiency than MRP1 and unexpectedly, GSH inhibited rather than stimulated uptake. These studies provide further insight into the complex interactions of the MRP-related proteins with GSH and their conjugated organic anion substrates, and extend the range of xenotoxins transported by MRP1 and MRP2 to include metabolites of known carcinogens involved in the etiology of lung and other cancers.

ATP-Binding Cassette Transporters↗
PubMed2001

Neuronal plasticity in hippocampal mossy fiber-CA3 synapses of mice lacking the inositol-1,4,5-trisphosphate type 1 receptor.

In the present study, we used inositol-1,4,5-trisphosphate (IP3) type 1 receptor (IP3R1) knockout mice to examine the role of this receptor in the induction of LTP, LTD, and DP at mossy fiber-CA3 synapses. No difference in synaptically induced field-EPSPs was seen between the wild-type (IP3R1(+/+)) and IP3R1 knockout mice (IP3R1(-/-)), showing that basic synaptic transmission does not involve IP3R1 activation. Tetanus induced LTP in both wild-type and IP(3)R1(-/-) mice, but the magnitude of LTP was significantly greater in IP3R1(-/-) mice (149.8+/-3.5%, mean+/-S.E.M., n=15) than in wild-type mice (132.4+/-1.5%, n=17), suggesting that the IP3R1 has a suppressive effect on LTP induction. To determine whether this effect involved N-methyl-D-aspartate receptor (NMDAR)-dependent LTP, the effect of tetanus was tested in the present of the NMDAR antagonist, D,L-AP5 (50 microM); under these conditions, the LTP in both IP3R1(-/-) and IP3R1(+/+) mice was not significantly reduced. In addition, group I mGluR activation was shown to be necessary for LTP induction, as the LTP was almost blocked by the group I mGluR antagonist, RS-4CPG (500 microM) in both IP3R1(-/-) (117.6+/-1.7%, n=8) and IP3R1(+/+) (116.9+/-1.8%, n=5) mice. The IP3R1 also plays an essential role in LTD induction, as low-frequency stimulation (LFS) failed to induce LTD in the mutant mice (104.5+/-2.1%, n=10). DP was induced in both IP3R1(-/-) and wild-type mice.

Animals↗
PubMed2001

Effect of the glycine modulatory site of the N-methyl-D-aspartate receptor on synaptic responses in kitten visual cortex.

In visual cortical slices taken from kittens, the administration of D-serine, an agonist of the N-methyl-D-aspartate receptor complex, significantly enhanced synaptically evoked responses using field potential recordings in lower layer II/III. Expression of normally appearing long-term potentiation (LTP) took place in the presence of the agonist during high-frequency stimulation (HFS). The administration of an antagonist of this receptor, 7-chloro-kynurenic acid (7-Cl KY) alone had no appreciable effect on low-frequency synaptic transmission while HFS failed to induce LTP. Combined administration of D-serine and 7-Cl KY resulted in no alteration of low-frequency synaptic transmission, although expression of LTP was normally obtained. These results suggest that in visual cortex of kittens, the availability of this glycine binding site of the NMDA receptor is necessary for the expression of LTP.

Animals↗
PubMed2001

Mitochondrial DNA alteration in esophageal cancer.

It has been reported that various cancers frequently have mutations in the D-loop region of mitochondrial DNA (mtDNA). We examined the genetic alterations in this region of esophageal cancer using direct sequencing. Of 68 sequence variants, 15 have not been reported to date. Tumor mtDNA with these variants were compared with mtDNA from corresponding normal esophageal mucosa. Two of 37 primary esophageal cancers (5%) contained somatic mutations in the D-loop region of mtDNA. Although the mutation rate of mitochondrial tumor DNA within the D-loop was not high, this result suggested that mtDNA mutations play a role in the development of esophageal cancer.

DNA Mutational Analysis↗
PubMed2001

An essential amino acid residue in the protein translocation channel revealed by targeted random mutagenesis of SecY.

The SecY/Sec61alpha family of membrane proteins are the central subunits of the putative protein translocation channel. We introduced random mutations into a segment of Escherichia coli SecY within its cytoplasmic domain 5, which was shown previously to be important for the SecA-dependent translocation activity. Mutations were classified into those retaining function and those gaining a dominant-interfering ability caused by a loss of function. These analyses showed that Arg-357, Pro-358, Gly-359, and Thr-362 are functionally important; Arg-357, conserved in almost all organisms, was identified as an indispensable residue.

Adenosine Triphosphatases↗
PubMed2001

Protein kinase C isoform-dependent modulation of ATP-sensitive K+ channels during reoxygenation in guinea-pig ventricular myocytes.

ATP-sensitive K+ (KATP) channels activated by glucose-free anoxia close immediately upon reoxygenation in single guinea-pig ventricular myocytes, while KATP channels open persistently during reperfusion in coronary-perfused guinea-pig ventricular myocardium. To investigate the reasons behind this discrepancy, we investigated whether protein kinase C (PKC) modulates the opening of KATP channels during anoxia-reoxygenation and ischaemia-reperfusion. Exposure of guinea-pig ventricular cells to glucose-free anoxia shortened the action potential duration at 90% repolarisation (APD90) and evoked the glibenclamide-sensitive robust outward current (IK,ATP). Subsequent reoxygenation caused an immediate prolongation of APD90 and a decrease in IK,ATP within approximately 20 s. When the novel (Ca2+-independent) PKC was activated by applying 1,2-dioctanoyl-sn-glycerol (1,2DOG, 20 M) with EGTA (20 mM) in the pipette, the APD90 restored gradually after reoxygenation and the extent of recovery was appoximately 80% of the pre-anoxic value. Moreover, IK,ATP decreased slowly and remained opened for up to approximately 4 min after reoxygenation. These results suggest persistent opening of KATP channels during reoxygenation. The persistent activation of KATP channels was augmented when both novel and conventional (Ca2+-dependent) isoforms of PKC were activated by applying 1,2DOG without EGTA in the pipette. In coronary-perfused right ventricular myocardium, APD90 remained shortened for up to approximately 30 min of reperfusion. The gradual restoration of APD90 after ischaemia-reperfusion was facilitated by the KATP channel blocker glibenclamide and by the potent PKC inhibitor chelerythrine. Our results provide the first evidence that PKC activation contributes to the persistent opening of KATP channels during reoxygenation and reperfusion. We also conclude that both novel and conventional PKC isoforms co-operatively modulate the opening of KATP channels during the early phase of reoxygenation.

Action Potentials↗
PubMed2001

Effect of pre-and postoperative plasmapheresis on posttransplant recurrence of focal segmental glomerulosclerosis in children.

BACKGROUND: Posttransplant recurrence is frequent in patients who received renal transplantation for focal segmental glomerulosclerosis (FSGS). The recurrence has been ascribed to a circulating permeability factor or factors. We have used plasmapheresis (PP) to treat recurrent FSGS and also studied whether preoperative PP is effective in preventing recurrence of FSGS. METHODS: We retrospectively analyzed 21 allografts of 20 patients with nephrotic syndrome and biopsyproven FSGS. They were divided into two groups depending on whether they had prophylactic PP; a prophylactic (n=15) and a nonprophylactic group (n=6). PP was performed two to three times prophylactically and therapeutically until proteinuria was markedly reduced. In each session, 50-75 ml/kg of the patient's plasma was exchanged with 5-8% albumin. RESULTS: FSGS recurred in 9 of 21 allografts, 4 of 6 in the nonprophylactic group, and 5 of 15 in the prophylactic group. Therapeutic PP was performed in seven of nine recurrent patients without definite adverse effect, with satisfactory results except in one patient. Children lost proteinuria after 6 to > 100 sessions of PP and the number correlated with the pretreatment level of proteinuria. The mean follow-up periods were 62.7 and 41.6 months for the prophylactic and nonprophylactic groups, respectively. At the last follow-up, 66.7% of relapsing and 81.8% of nonrelapsing patients had a functioning graft. CONCLUSION: PP appears to be effective for the prevention and treatment of posttransplant recurrence of FSGS, although further consideration of cost/benefit and risks is required before a conclusive judgement can be made.

Child↗
PubMed2001

Characterization of bile acid transport mediated by multidrug resistance associated protein 2 and bile salt export pump.

Biliary excretion of certain bile acids is mediated by multidrug resistance associated protein 2 (Mrp2) and the bile salt export pump (Bsep). In the present study, the transport properties of several bile acids were characterized in canalicular membrane vesicles (CMVs) isolated from Sprague--Dawley (SD) rats and Eisai hyperbilirubinemic rats (EHBR) whose Mrp2 function is hereditarily defective and in membrane vesicles isolated from Sf9 cells infected with recombinant baculovirus containing cDNAs encoding Mrp2 and Bsep. ATP-dependent uptake of [(3)H]taurochenodeoxycholate sulfate (TCDC-S) (K(m)=8.8 microM) and [(3)H]taurolithocholate sulfate (TLC-S) (K(m)=1.5 microM) was observed in CMVs from SD rats, but not from EHBR. In addition, ATP-dependent uptake of [(3)H]TLC-S (K(m)=3.9 microM) and [(3)H]taurocholate (TC) (K(m)=7.5 microM) was also observed in Mrp2- and Bsep-expressing Sf9 membrane vesicles, respectively. TCDC-S and TLC-S inhibited the ATP-dependent TC uptake into CMVs from SD rats with IC(50) values of 4.6 microM and 1.2 microM, respectively. In contrast, the corresponding values for Sf9 cells expressing Bsep were 59 and 62 microM, respectively, which were similar to those determined in CMVs from EHBR (68 and 33 microM, respectively). By co-expressing Mrp2 with Bsep in Sf9 cells, IC(50) values for membrane vesicles from these cells shifted to values comparable with those in CMVs from SD rats (4.6 and 1.2 microM). Moreover, in membrane vesicles where both Mrp2 and Bsep are co-expressed, preincubation with the sulfated bile acids potentiated their inhibitory effect on Bsep-mediated TC transport. These results can be accounted for by assuming that the sulfated bile acids trans-inhibit the Bsep-mediated transport of TC.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

The mechanism of aubstrate eecognition of pyroglutamyl-peptidase I from Bacillus amyloliquefaciens as determined by X-ray crystallography and site-directed mutagenesis.

Pyroglutamyl-peptidase is able to specifically remove the amino-terminal pyroglutamyl residue protecting proteins or peptides from aminopeptidases. To clarify the mechanism of substrate recognition for the unique structure of the pyrrolidone ring, x-ray crystallography and site-directed mutagenesis were applied. The crystal structure of pyroglutamyl-peptidase bound to a transition state analog inhibitor (Inh), pyroglutaminal, was determined. Two hydrogen bonds were located between the main chain of the enzyme and the inhibitor (71:O.H-N:Inh and Gln71:N-H.OE:Inh), and the pyrrolidone ring of the inhibitor was inserted into the hydrophobic pocket composed of Phe-10, Phe-13, Thr-45, Ile-92, Phe-142, and Val-143. To study in detail the hydrophobic pocket, Phe-10, Phe-13, and Phe-142 were selected for mutation experiments. The k(cat) value of the F10Y mutant decreased, but the two phenylalanine mutants F13Y and F142Y did not exhibit significant changes in kinetic parameters compared with the wild-type enzyme. The catalytic efficiencies (k(cat)/K(m)) for the F13A and F142A mutants were less than 1000-fold that of the wild-type enzyme. The x-ray crystallographic study of the F142A mutant showed no significant change except for a minor one in the hydrophobic pocket compared with the wild type. These findings indicate that the molecular recognition of pyroglutamic acid is achieved through two hydrogen bonds and an insertion in the hydrophobic pocket. In the pocket, Phe-10 is more important to the hydrophobic interaction than is Phe-142, and furthermore Phe-13 serves as an "induced fit" mechanism.

Amino Acid Sequence↗
PubMed2001

Mutation of a single conserved tryptophan in multidrug resistance protein 1 (MRP1/ABCC1) results in loss of drug resistance and selective loss of organic anion transport.

Multidrug resistance protein 1 (MRP1/ABCC1) belongs to the ATP-binding cassette transporter superfamily and is capable of conferring resistance to a broad range of chemotherapeutic agents and transporting structurally diverse conjugated organic anions. In this study, we found that substitution of a highly conserved tryptophan at position 1246 with cysteine (W1246C-MRP1) in the putative last transmembrane segment (TM17) of MRP1 eliminated 17beta-estradiol 17-(beta-d-glucuronide) (E(2)17betaG) transport by membrane vesicles prepared from transiently transfected human embryonic kidney cells while leaving the capacity for leukotriene C(4)- and verapamil-stimulated glutathione transport intact. In addition, in contrast to wild-type MRP1, leukotriene C(4) transport by the W1246C-MRP1 protein was no longer inhibitable by E(2)17betaG, indicating that the mutant protein had lost the ability to bind the glucuronide. A similar phenotype was observed when Trp(1246) was replaced with Ala, Phe, and Tyr. Confocal microscopy of cells expressing Trp(1246) mutant MRP1 molecules fused at the C terminus with green fluorescent protein showed that they were correctly routed to the plasma membrane. In addition to the loss of E(2)17betaG transport, HeLa cells stably transfected with W1246C-MRP1 cDNA were not resistant to the Vinca alkaloid vincristine and accumulated levels of [(3)H]vincristine comparable to those in vector control-transfected cells. Cells expressing W1246C-MRP1 were also not resistant to cationic anthracyclines (doxorubicin, daunorubicin) or the electroneutral epipodophyllotoxin VP-16. In contrast, resistance to sodium arsenite was only partially diminished, and resistance to potassium antimony tartrate remained comparable to that of cells expressing wild-type MRP1. This suggests that the structural determinants required for transport of heavy metal oxyanions differ from those for chemotherapeutic agents. Our results provide the first example of a tryptophan residue being so critically important for substrate specificity in a eukaryotic ATP-binding cassette transporter.

ATP-Binding Cassette Transporters↗
PubMed2001

Dimerization with PEBP2beta protects RUNX1/AML1 from ubiquitin-proteasome-mediated degradation.

The RUNX family genes are the mammalian homologs of the Drosophila genes runt and lozenge, and members of this family function as master regulators of definitive hematopoiesis and osteogenesis. The RUNX genes encode the alpha subunit of the transcription factor PEBP2/CBF. The beta subunit consists of the non-RUNX protein PEBP2beta. We found that RUNX1/AML1, which is essential for hematopoiesis, is continuously subjected to proteolytic degradation mediated by the ubiquitin-proteasome pathway. When PEBP2beta is present, however, the ubiquitylation of RUNX1 is abrogated and this causes a dramatic inhibition of RUNX1 proteolysis. Heterodimerization between PEBP2beta and RUNX1 thus appears to be an essential step in the generation of transcriptionally competent RUNX1. Consistent with this notion, RUNX1 was barely detected in PEBP2beta(-/-) mouse. CBF(PEBP2)beta- SMMHC, the chimeric protein associated with inv(16) acute myeloid leukemia, was found to protect RUNX1 from proteolytic degradation more efficiently than PEBP2beta. These results reveal a hitherto unknown and major role of PEBP2beta, namely that it regulates RUNX1 by controlling its turnover. This has allowed us to gain new insights into the mechanism of leukemogenesis by CBFbeta-SMMHC.

Amino Acid Sequence↗
PubMed2001

Long term follow-up of mass screening for prostate carcinoma in men with initial prostate specific antigen levels of 4.0 ng/ml or less.

BACKGROUND: Long term follow-up for subjects whose initial prostate specific antigen (PSA) levels were 4.0 ng/mL or lower was conducted to investigate the proper interval for PSA screening. METHODS: Eight thousand five hundred ninety-five men aged 50 years or older with an initial PSA level of 4.0 ng/mL or lower were screened with tumor marker measurement and/or digital rectal examination (DRE) and/or transrectal ultrasonography as a first step in the mass screening, and a prostate biopsy was performed for individuals with abnormal findings. RESULTS: Cancer was detected in 0.18% (8 of 4526), 1.0% (27 of 2724), and 3.6% (49 of 1345) of men whose initial PSA levels were lower than 1.0, 1.0-1.9, and 2.0-4.0 ng/mL, respectively. Among these prostate carcinoma cases, 25% (6 of 8), 56% (15 of 27), and 63% (31 of 49) were detected by abnormal PSA in patients with initial PSA levels lower than 1.0, 1.0-1.9, and 2.0-4.0 ng/mL, respectively. The detection rates of prostate carcinoma within 3 years after the initial visit were 0.07%, 0.24%, and 1.2% in cases with initial PSA levels lower than 1.0, 1.0-1.9, and 2.0-4.0 ng/mL, respectively. CONCLUSIONS: It is recommended that DRE and PSA measurements should be performed once every 3 years in individuals with initial PSA levels of less than 1.0 ng/mL. The prostate carcinoma detection rate increased over time in individuals with initial PSA levels of 1.0 to 4.0 ng/mL, especially in cases with 2.0-4.0 ng/mL, and annual measurement of PSA was more useful than DRE. Therefore, it is recommended that PSA screening should be performed once every year for individuals with initial PSA levels of 1.0 to 4.0 ng/mL.

Aged↗
PubMed2001

Determination of bufalin-like immunoreactivity in serum of humans and rats by time-resolved fluoroimmunoassay for using a monoclonal antibody.

The existence of a mammalian natriuretic substance or endogenous digitalis-like factor, which inhibits Na+,K+-ATPase and thereby regulates body fluid volume, has been speculated for a long time but has yet to be defined. We established in the present study a simple and highly sensitive procedure to measure bufalin, a constituent of toad venom preparation and a specific inhibitor of Na+,K+-ATPase by time-resolved fluoroimmunoassay (TR-FIA) and using a monoclonal antibody. The antibody was specific to bufalin and resembled bufadienolides but showed no cross-reactivity with digitoxin and ouabain. A bufalin-like immunoreactivity was detectable in serum of humans and rats by the proposed TR-FIA. The levels of bufalin-like immunoreactivity in serum of healthy volunteers were significantly correlated with their systolic blood pressure. Moreover, bufalin-like immunoreactivity in serum of Dahl-S rats increased in parallel with a period of high-salt diet. These results suggest that increased bufalin-like immunoreactivity may be associated with certain types of hypertension.

Animals↗
PubMed2001

Revisiting the lysogenization control of bacteriophage lambda. Identification and characterization of a new host component, HflD.

Upon infection to the Escherichia coli cell, the genome of bacteriophage lambda either replicates to form new progenies (lytic growth) or integrates into the host chromosome (lysogenization). The lambda CII protein is a key determinant in the lysis-lysogeny decision. It is a short-lived transcription activator for the lambda genes essential for lysogeny establishment. In this study, we isolated a new class of hfl (high frequency lysogenization) mutants of E. coli, using a new selection for enhancement of CII-stimulated transcription. The gene affected was termed hflD, which encodes a protein of 213 amino acids. An hflD-disrupted mutant indeed showed an Hfl phenotype, indicating that HflD acts to down-regulate lysogenization. HflD is associated peripherally with the cytoplasmic membrane. Its interaction with CII was demonstrated in vitro using purified proteins as well as in vivo using the bacterial two-hybrid system. Pulse-chase examinations demonstrated that the HflD function is required for the rapid in vivo degradation of CII, although it interfered with FtsH-mediated CII proteolysis in an in vitro reaction system using detergent-solubilized components. We suggest that HflD is a factor that sequesters CII from the target promoters and recruits it to the membrane where the FtsH protease is localized.

Bacteriophage lambda↗
PubMed2001

Attractin/mahogany/zitter plays a critical role in myelination of the central nervous system.

The rat zitter (zi) mutation induces hypomyelination and vacuolation in the central nervous system (CNS), which result in early-onset tremor and progressive flaccid paresis. By positional cloning, we found a marked decrease in Attractin (Atrn) mRNA in the brain of the zi/zi rat and identified zi as an 8-bp deletion at a splice donor site of Atrn. Atrn has been known to play multiple roles in regulating physiological processes that are involved in monocyte-T cell interaction, agouti-related hair pigmentation, and control of energy homeostasis. Rat Atrn gene encoded two isoforms, a secreted and a membrane form, as a result of alternative splicing. The zi mutation at the Atrn locus darkened coat color when introduced into agouti rats, as also described in mahogany (mg) mice, carrying the homozygous mutation at the Atrn locus. Transgenic rescue experiments showed that the membrane-type Atrn complemented both neurological alteration and abnormal pigmentation in zi/zi rats, but that the secreted-type Atrn complemented neither mutant phenotype. Furthermore, we discovered that mg mice exhibited hypomyelination and vacuolation in the CNS associated with body tremor. We conclude from these results that the membrane Atrn has a critical role in normal myelination in the CNS and would provide insights into the physiology of myelination as well as the etiology of myelin diseases.

Agouti Signaling Protein↗
PubMed2001

Neurogenic failures of the external urethral sphincter closure and relaxation; a videourodynamic study.

Urinary urgency and voiding difficulty are common features in neurological diseases, which can be attributed to dysfunction of the urethral sphincter and the detrusor. However, little is known about dynamic sphincter behaviour in neurological diseases. The present study aimed at investigating neurogenic failures of the external urethral sphincter closure and relaxation by videourodynamic study. We recruited 44 neurological patients with urinary urgency and frequency, 27 men and 17 women, mean age 61 years, and 28 of them had voiding difficulty as well. None had abnormal finding of digital examination or ultrasound echography of the pelvic organs. Using triple-lumen 7F catheter under X-ray fluoroscope, we measured detrusor pressure, external urethral sphincter pressure (Pura) and external sphincter EMG in all patients. We also performed pressure-flow study and obtained the Abram-Griffiths (AG) number, a numerical grade of obstruction. During filling 30 had detrusor hyperreflexia. EMG-cystometry showed uninhibited external sphincter relaxation (UESR) in eight patients, seven of whom had detrusor hyperreflexia as well. Patients with UESR showed an abnormal reduction of Pura, mean reduction 64 +/- 27 cmH2O (mean +/- standard deviation). During UESR the Pura and EMG activity fluctuated, and fluoroscopic image showed bladder neck opening in four with extreme urge sensation, including one without detrusor hyperreflexia. During an attempt of voiding three patients with voiding difficulty had detrusor-external sphincter dyssynergia (DESD) with detrusor contraction and eight had unrelaxing external sphincter without detrusor contraction. Fluoroscopic image showed an incomplete or absent urethral opening at the external sphincter. Four of them had severe straining on voiding together with intermittent increment of EMG activity without a normal funneling of the bladder neck. The mean reduction of Pura during voiding was 6.4 +/- 6.7 cmH2O and 5.0 +/- 9.5 cmH2O (in women and men, respectively) with DESD or unrelaxing external sphincter which was less than 39 +/- 25 cmH2O and 53 +/- 47 cmH2O in those without (P < 0.01). The mean AG number was 15 +/- 21 and 51 +/- 19 (for women and men, respectively) with DESD or unrelaxing external sphincter which was larger than 6.2 +/- 34 and 35 +/- 22 in those without (P < 0.05). In conclusion, UESR and DESD/unrelaxing external sphincter could be a factor for urinary urgency and voiding difficulty in neurological patients, evidence of central dysregulation affecting the Onuf's nucleus and its fibres to the external urethral sphincter.

Adolescent↗