Search PubMed⌕ Search

Biomedical subjects

K Yasuda

Publications and source records attributed to K Yasuda.

At least 379 records · Page 21Linked to original sources
PubMed1998

Induction of lens differentiation by activation of a bZIP transcription factor, L-Maf.

After the vertebrate lens is induced from head ectoderm, lens-specific genes are expressed. Transcriptional regulation of the lens-specific alphaA-crystallin gene is controlled by an enhancer element, alphaCE2. A gene encoding an alphaCE2-binding protein, L-maf(lens-specific maf), was isolated. L-maf expression is initiated in the lens placode and is restricted to lens cells. The gene product L-Maf regulates the expression of multiple genes expressed in the lens, and ectopic expression of this transcription factor converts chick embryonic ectodermal cells and cultured cells into lens fibers. Thus, vertebrate lens induction and differentiation can be triggered by the activation of L-Maf.

Amino Acid Sequence↗
PubMed1998

The effects of serum iminodipeptides and prednisolone on superoxide generation and tyrosyl phosphorylation of proteins in neutrophils from a patient with prolidase deficiency.

The aim of this study was to examine the effects of serum iminodipeptides and prednisolone on superoxide generation and tyrosyl phosphorylation of proteins in neutrophils from a patient with prolidase deficiency, and also to find the causative effects of superoxide on inflammatory skin lesions. When the neutrophils from a patient with prolidase deficiency (PDPPMN) were preincubated with prolyl-proline (Pro-Pro), which is one of the iminodipeptides found at high concentration in the serum of patients with prolidase deficiency, the N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide generation was enhanced in a concentration-dependent manner, although the extent of enhancing effect was lower than that in neutrophils from healthy humans (HPPMN). Pro-Pro also enhanced superoxide generation induced by opsonized zymosan (OZ) in PDPPMN but not that induced by arachidonic acid or phorbol 12-myristate 13-acetate. Herbimycin A and genistein decreased the fMLP- and OZ-induced superoxide generations after priming by Pro-Pro. 1-(5-isoquinoline-sulfonyl)-2-methyl-piperazine (H-7) and staurosporine did not decrease, but rather enhanced, the superoxide generation in a low concentration range. When PDPPMN were prepared, tyrosyl phosphorylation of 45 kDa protein in PDPPMN had already occurred. The phosphorylation was scarcely increased by incubation of the cells with Pro-Pro, in contrast to that in HPPMN. Genistein decreased the phosphorylation of 45 kDa protein in both PDPPMN and HPPMN. These results suggest that the priming effect of iminodipeptides on superoxide generation in PDPPMN is coupled with phosphorylation of 45 kDa protein by protein tyrosine kinase. Protein tyrosine kinase may play a critical role(s) in the regulatory mechanism of priming by iminodipeptides and activation of NADPH oxidase in the patient's neutrophils. In prolidase deficiency, the characteristic skin manifestations are inflammatory indurations and chronic leg ulcers. Prednisolone improves the ulcers, and this compound decreased the fMLP- and OZ-induced superoxide generation and tyrosyl phosphorylation of 45 kDa protein in the patient's neutrophils after priming by Pro-Pro. When inflammatory skin lesions were present, the levels of iminodipeptides in the patient's serum were elevated and the superoxide generation by neutrophils was up-regulated. When skin lesions were healing or absent, the levels of iminodipeptides in the patient's serum and superoxide generation by neutrophils were higher than those of healthy controls but lower than those in the inflammatory stages. Thus, the enhancement of superoxide generation by neutrophils via serum iminodipeptides would be one of the inducers of inflammatory skin lesions. Corticosteroid administration might be a therapeutic modality of choice for skin lesions.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1998

A novel superoxide dismutase gene encoding membrane-bound and extracellular isoforms by alternative splicing in Caenorhabditis elegans.

We have identified a novel Cu/Zn superoxide dismutase gene (termed SOD-4) in Caenorhabditis elegans. Characterization of its complementary DNA revealed that the gene encodes two isoforms by alternative splicing, SOD4-1 and SOD4-2 which differ in their C-terminal exons. Their predicted amino acid sequences include a consensus signal peptide at their N-termini and are homologous to the extracellular-types of Cu/Zn superoxide dismutase in mammals. In addition, SOD4-2 possesses a putative transmembrane domain at the C-terminal region. When transiently expressed in Chinese hamster ovary cells, both types were found in the membranes and SOD4-1 also in the culture fluid. It is, therefore, indicated that SOD4-1 is an extracellular form and SOD4-2 a membrane-bound form, the latter representing a novel type of SOD. In C. elegans, SOD4-2 mRNA was found to be preferentially expressed in eggs.

Alternative Splicing↗
PubMed1998

Human MDR1 and mouse mdr1a P-glycoprotein alter the cellular retention and disposition of erythromycin, but not of retinoic acid or benzo(a)pyrene.

The intracellular concentration of many steroids and xenobiotics is influenced by the membrane protein P-glycoprotein (Pgp). It has been inferred that the intracellular retention of many drugs that upregulate Pgp or modulate Pgp function might also be affected by Pgp. However, the ability of Pgp to influence the translocation of these drugs needs to be established to understand Pgp's influence upon their pharmacological effect. We utilized two approaches to determine the interaction of several agents with Pgp: (a) an in vitro system, LLC-PK1 cell lines and derivative LLC cell lines stably expressing on the apical membrane either mouse mdr1a or human MDR1 Pgp grown as polarized epithelium in transwell culture to measure translocation of radiolabeled drugs; and (b) an in vivo system, mdr1a nullizygous and wild-type animals, to compare the contribution of Pgp to in vivo distribution of radiolabeled drugs. In combination these complementary approaches identified erythromycin as a drug whose intracellular retention is influenced by Pgp, while the intracellular accumulation and tissue distribution of retinoic acid and benzo(a)pyrene were unaffected by Pgp.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1998

Comprehension of famous personal and geographical names in global aphasic subjects.

This experiment compared comprehension of famous personal and geographical names with that of common nouns in three groups of severe aphasic subjects across three modalities. Results revealed that the global aphasic group comprehended famous personal names significantly better than they did common nouns and were better in the reading comprehension modality. Comprehension of famous geographical names in the global aphasic group, however, was as impaired as that of common nouns. CT images suggested that the left occipital lobe and the left posterior inferior temporal gyrus, as well as the right hemisphere, may have relevance to the comprehension of written famous personal names.

Aged↗
PubMed1998

Micturitional disturbance in a patient with adrenomyeloneuropathy (AMN).

We report a case of adrenomyeloneuropathy (AMN) in which serial urodynamic studies showed neurogenic bladder dysfunction. The patient was in good health until the age of 12, when he began to lose his hair. At age 25 he started to have urinary urgency, difficulty in voiding, occasional fecal incontinence, erectile impotence, and progressive gait disturbance. In his first admission to our hospital age 31, he was intelligent but childish. He showed diffuse baldness, spastic paraparesis, and disturbed vibratory sensation. Serum cortisol response to corticotropin (ACTH) was low and serum levels of very long chain fatty acids were increased. Nerve conduction studies and sural nerve biopsy showed the presence of peripheral neuropathy. These findings confirmed the diagnosis of AMN. The first urodynamic study showed residual urine volume of 50 ml, impaired bladder sensation, and detrusor hyperreflexia. At age 38 he needed diapers because he became apathetic and demented, and could no longer stand by himself. MRI disclosed high signal intensities in the bilateral cerebral white matter. The second urodynamic study showed residual urine volume of 200 ml and decreased bladder capacity with marked detrusor hyperreflexia. Demyelinating lesions of the peripheral nerve and white matter of the spinal cord and the cerebrum may be mainly responsible for the micturitional disturbance in our patient with AMN.

Adrenoleukodystrophy↗
PubMed1998

Urinary retention due to herpes virus infections.

Urinary retention is uncommon in patients with herpes zoster and anogenital herpes simplex. Seven patients (four men, three women) with a mean age of 68.1 years (range, 35-84) with urinary retention due to herpes zoster (n = 6) or anogenital herpes simplex (n = 1) were studied. Six patients had unilateral skin eruption in the saddle area (S2-4 dermatome) and one patient with herpes zoster had a skin lesion in the L4-5 dermatome. All patients had detrusor areflexia without bladder sensation, and two of them had inactive external sphincter on electromyography at presentation. Clean intermittent catheterization was performed, and voiding function was recovered in 4-6 weeks (average, 5.4) in all patients. Urodynamic study was repeated after recovery of micturition in three patients, and they returned to normal on cystometrography and external sphincter electromyography. Acute urinary retention associated with anogenital herpes infection has been thought to occur when the meninges or sacral spinal ganglia were involved, and, in conclusion, this condition may be considered to be reversible.

Acyclovir↗
PubMed1998

Precore wild-type DNA and immune complexes persist in chronic hepatitis B after seroconversion: no association between genome conversion and seroconversion.

Precore hepatitis B virus (HBV) mutants may gradually prevail during or after seroconversion (SC) from hepatitis B e antigen (HBeAg) to hepatitis B e antigen antibody (anti-HBe) status in many chronic hepatitis B (CH-B) patients. However, patients with CH-B still produce anti-HBe more than several years after SC, and the relationship between SC and genome conversion in the precore region has not been clarified. Therefore, in patients with CH-B who had a sustained loss of HBeAg and complete remission of hepatitis after SC, the precore region was sequenced in paired serum samples from 1 year before SC to 3 years after SC. Mutant precore defective HBV DNA was found in only 6 (19%) of 31 CH-B patients who had a complete remission of hepatitis after SC. Mixed-type HBV DNA (precore wild-type and mutant-type) was found in 4 (13%) patients. Wild-type HBV DNA was found in 21 (68%) CH-B patients after SC. Longer-term follow-up of 11 CH-B patients indicated that 3 of 11 patients experienced precore genome conversion 2 to 3 years after SC. E-plus DNA or e-minus DNA was semiquantitated by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) assays before and after SC. E-plus DNA levels decreased from 10(5.56+/-1.58) to 10(2.45+/-1.61). Similarly, e-minus DNA levels declined from 10(4.25+/-1.56) to 10(1.86+/-1.37). By dot-blot assay, serum HBV DNA became negative soon after SC, as did serum HBeAg. In contrast, HBeAg-containing immune complexes were still detected after SC. Anti-HBe antibody was produced throughout SC and thereafter, as determined by a sensitive experimental assay. Therefore, we conclude that genome-conversion in the precore region is a separate event from HBeAg/anti-HBe seroconversion.

Acute Disease↗
PubMed1998

Persistent viremia after recovery from self-limited acute hepatitis B.

To define the duration of viremia in the course of acute hepatitis B, we semiquantitatively determined the levels of hepatitis B virus (HBV) DNA in the sera, using polymerase chain reaction (PCR) coupled with Southern blotting, of non-immunocompromised patients with self-limited acute hepatitis B. In the sera of 10 of 11 patients, HBV DNA, which was presumably coated with viral proteins, was detected for a long period after recovery, even at the final observation times, which ranged from 6 to 19 months after disease onset. To characterize the mode of HBV that was present in serum, we immunoprecipitated immune complexes in sera by the addition of anti-human immunoglobulin G (IgG) and determined the levels of HBV DNA separately in the supernatants and pellets. In the acute phase of hepatitis B, high levels of HBV DNA were detected both in the supernatants and pellets at comparative levels. After the convalescent phase, the amount of HBV DNA in the supernatant decreased with respect to that in the pellets. It is notable that, in most cases, serum HBV persisted as a form of immune complex even after the seroconversion to antibody to hepatitis B surface antigen (anti-HBs). These data suggest that the replication of HBV may persist in some organs, most likely in the liver or peripheral blood cells, for a long period after recovery from acute hepatitis B, and the data indicate the possible transmission of HBV from organ transplantation donors who exhibit serological markers of past infection only.

Acute Disease↗
PubMed1998

Electrical stimulation for stress incontinence.

Electrical stimulation has been reported to be effective for stress incontinence, cure and improvement rates being reported to range from 30% to 50%, and from 6% to 90%, respectively. However, clinical application of this treatment is not common because there is little physiological and technical information. Electrodes for electrical stimulation are divided into two types: external (non-implantable) and internal (implantable), and there are two methods of stimulation: chronic (long-term, continuous) and short-term. Frequencies of 20-50 Hz, with a pulse duration of 1-5 ms, have been reported to be effective for urethral closure. The effectiveness of the treatment should be verified with placebo-controlled double-blinded trials, and four such studies using an active and a sham device have been reported. Two of these verified the superiority of the active device over the sham device, but the others did not demonstrate any significant difference between the two with regard to efficacy. Electrical stimulation has been reported to result in a long-term continuation of therapeutic effect. The effect has been explained as a re-education or a reactivation of lost functions of the pelvic floor muscles. As to adverse effects, there may be some complications in relation to anesthesia or surgical procedures, such as infection, pain and bleeding with implantable electrodes. The incidence of adverse effects in short-term electrical stimulation is less than 14%. In conclusion, short-term electrical stimulation using non-implantable anal or vaginal electrodes is the most recommendable because of safety and ease of use.

Electric Stimulation Therapy↗
PubMed1998

Determinants of postoperative and long-term survival of patients with ruptured abdominal aortic aneurysms.

To compare the surgical results of patients with ruptured (rAAA) and nonruptured abdominal aortic aneurysms (NrAAA), 267 consecutive patients surgically treated for abdominal aortic aneurysms (AAA) were reviewed. The patients' characteristics, preexistent risk factors, perioperative factors, and postoperative early and long-term survival were compared between the rAAA group (n = 27) and the NrAAA group (n = 240). A multivariate analysis to predict postoperative survival was also conducted in the rAAA group. The hospital mortality rate was 3.3% (8/232) for the NrAAA group and 22.2% (6/27) for the rAAA group (P < 0.001). The maximum size of aneurysms, period of preoperative hypotension, and intraoperative bleeding volume were significantly higher in the rAAA group than in the NrAAA group. The 5- and 10-year cumulative survival rates in the rAAA group were 88.1% and 42.0%, which were comparable to those in the NrAAA group. The incremental risk factors for hospital death in the rAAA group included advanced age, preoperative hypotension (< 80 mmHg), and postoperative renal failure requiring dialysis. These findings showed that the interval from rupture to cross-clamping must be shortened, maintaining hemodynamic stability to avoid prolonged hypotension. Reducing risk factors and minimizing deterioration of organ functions postoperatively would be essential to improve the prognosis of patients with rAAA.

Aged↗
PubMed1998

Myxoma of the mitral valve prolapsing into the left atrium and ventricle: report of a case.

A rare case of myxoma originating from the mitral valve is reported. A 25-year-old woman was found to have a mobile mass around the mitral valve that prolapsed into the left atrium and the left ventricular outflow tract. The mitral valve was approached via the left atrium and aorta, and was excised completely along with the tumor; it was thus replaced with a mechanical prosthesis. The patient recovered and demonstrated no signs of recurrence 16 months postoperatively.

Adult↗
PubMed1998

Development of a non-invasive treatment system for urinary incontinence using a functional continuous magnetic stimulator (FCMS).

A system composed of a functional continuous magnetic stimulator (FCMS) and a saddle-type coil has been developed for non-invasive treatment of urinary incontinence, especially stress incontinence and urge incontinence. The FCMS conditions were as follows: 2 kW maximum electrical power consumption, 800 V maximum capacitor voltage, 720 microseconds pulsewidth (180 microseconds rise time), and 5-30 Hz frequency. A frequency between 5 and 10 Hz is used to treat urge incontinence and a frequency between 25 Hz and 30 Hz is used to treat stress incontinence. The coil (120 mm long, 90 mm wide and 50 mm thick) fits the most suitable region for this treatment, the region from the anus to the perineum. The coil is cooled to maintain a coil temperature between 20 and 25 degrees C so that it can be used efficiently and safely. In experiments with anaesthetised dogs, it was confirmed that the urethral pressure increased when the circumference of the perineum received continuous magnetic stimulation of 720 microseconds pulsewidth (180 microseconds rise time), 10 Hz frequency and about 520 V capacitor voltage. This result suggests that magnetic stimulation can be effective as a urinary incontinence therapy.

Animals↗
PubMed1998

Enhanced human tumor cell transplantability in a new congenic immunodeficient mouse; KSN-BNX.

We introduced two mutant genes (beige; bg that induces the deficiency of natural killer (NK) activity and xid that decreases the production of immunoglobulin) into KSN nude mice with high reproductive performances. We produced KSN bg/bg(nu/nu) (KSN-bg), KSN-xid/xid(nu/nn) (KSN-xid), KSN xid/xid,bg/bg(nu/nu) (KSN-BNX) and KSN-nu/+ (KS) mice by back-cross (cross-intercross method). All strains showed as high a reproductivity rate as the parental KSN mice. KSN-xid and KSN-BNX mice had a reduced percentage of B220 positive cells in the spleens compared to KSN and KSN-bg mice, but they showed increased percentages of Thy-1 and asialo GM1 positive cells. The serum immunoglobulin concentrations of KSN-BNX were as low as KSN-xid. Both KSN-bg and KSN-BNX mice showed deficient NK activity in spleens, whereas KSN-xid mice showed an elevated NK activity. Compared to nude mice, the growth of both human tumor cell TCO-1 and BxPc-3 transplanted subcutaneously was enhanced in KSN-BNX mice. However Panc-1 cells that was rejected in nude mice was not accepted in KSN-BNX mice. Liver metastasis of human pancreatic tumor cells; Capan-1, BxPc-3 and MIAPaCa-2 were studied. No significant difference was observed in the percentage of metastasis formed mice between nude and KSN-BNX mice.

Animals↗
PubMed1998

[Surgical treatment for perforated aorta caused by mediastinitis after bidirectional Glenn shunt and closure of atrial septal defect--a case report].

A 24-year-old man with Ebstein anomaly underwent a bidirectional Glenn shunt and closure of an atrial septal defect. Postsurgical prulent mediastinitis was treated by irrigation and drainage, but was followed by rupture of the ascending aorta. During emergency surgery, hypothermic circulatory arrest became necessary due to massive bleeding. Since he had undergone a bidirectional Glenn shunt, left heart venting was essential to obtain deep hypothermic circulatory arrest without cardiac distention and was successfully performed via an anterior thoracotomy approach. The perforated site of the ascending aorta was repaired with a Xeromedica patch. The anterior mediastinum was wrapped with the omentum. Transthoracic left heart venting via an anterior thoracotomy is an useful approach when hypothermic circulatory arrest is required to perform a median sternotomy and to approach the heart.

Adult↗
PubMed1998

Significance of graft tension in anterior cruciate ligament reconstruction. Basic background and clinical outcome.

The purpose of this paper is to review scientific evidence that graft tension affects remodelling of the autograft in ligament reconstruction. The in situ freezing model of the patellar tendon, an ideal patellar tendon autograft model, demonstrated that subsequent cellular proliferation following fibroblast necrosis reduces the mechanical properties of the autograft. Stress shielding enhances reduction of the strength in the once-frozen patellar tendon. The strength of the patellar tendon also changes depending on the degree of stress shielding. Transmission electron micrographs revealed that the number of small-diameter fibrils decreases in the stress-shielded tendons compared with non-stress-shielded tendons after in situ freezing. Restressing essentially restores the mechanical properties of patellar tendon autografts even if the strength has been much reduced by complete stress shielding. The effects of restressing may depend on the period of stress shielding applied before restressing. Unphysiologically high tension significantly reduces the mechanical properties of the in situ frozen anterior cruciate ligament (ACL). Therefore, not only stress-deprivation but also stress-enhancement significantly affect the mechanical properties of tendon autografts. Results of in vivo and in vitro studies suggest that cyclic tensile loading may inhibit the deterioration in mechanical strength of the transplanted tendon. Clinically, our prospective randomized study demonstrated that a relatively high initial tension reduces the postoperative anterior laxity of the knee joint after ACL reconstruction using the doubled autogenous hamstring tendons connected in series with polyester tapes, when the tension applied is less than 80 N. Our experimental and clinical results indicate that the initial tension is one of the significant factors that affect the results of ACL reconstruction, although the optimal initial tension for the other graft materials still remains unknown.

Animals↗
PubMed1998

Effects of dynamic cardiomyoplasty on left ventricular systolic and diastolic performance in an acute canine model.

Although dynamic cardiomyoplasty (DCMP) is currently being evaluated as an alternative to end-stage congestive heart failure, the overall results of DCMP are variable and inconclusive. We evaluated the effect of classic DCMP on systolic and diastolic cardiac function in normal heart using reliable indicators which minimize the influences of load conditions. Six experimental dogs were evaluated with the acute nonpreconditioning model. The slope of the linear preload recruitable stroke work relationship (Mw) showed a significant increase with latissimus dorsi muscle (LDM) stimulation (postwrap non-stimulation 59.1+/-6.3, postwrap stimulation 98.6+/-9.7 erg cm(-3) x 10(3); P < 0.01), and the x-intercept (V0) was unchanged; these were utilized as the indicators of left ventricular systolic function. The constant of pressure decay (tau) increased after LDM wrap (prewrap 45.8+/-6.0, postwrap nonstimulation 69.3+/-10.3, postwrap stimulation 72.3+/-13.9 ms; P < 0.05), and the peak filling rate was unchanged after LDM wrap, which were utilized as the indicators of diastolic function. We concluded that classic dynamic cardiomyoplasty is effective in assisting systolic cardiac function, but may to some degree have a detrimental effect on the diastolic cardiac function.

Animals↗