Search PubMed⌕ Search

Biomedical subjects

K Terada

Publications and source records attributed to K Terada.

At least 181 records · Page 10Linked to original sources
PubMed1995

Secretion, surface localization, turnover, and steady state expression of protein disulfide isomerase in rat hepatocytes.

Protein disulfide isomerase in isolated rat hepatocytes was present at a concentration of 7 micrograms/mg cell protein, representing a approximately 2-fold enrichment compared to isolated hepatic non-parenchymal cells. Though localized mainly in microsomal fractions of hepatocytes, direct immunofluorescence and cell surface radioiodination followed by immunoprecipitation revealed the presence of M(r) 57,000 disulfide isomerase at the cell surface. Electrostatic interaction of the protein with the cell surface was suggested by susceptibility to carbonate washing. Metabolic radiolabeling and immunoprecipitation studies also indicated that some of the newly synthesized M(r) 57,000 disulfide isomerase was secreted. Treatment of cells with colchicine markedly reduced the recovery of disulfide isomerase from the media, indicating microtubular-directed secretion of the protein. Partial staphlococcal V8 proteolytic digestion of the secreted protein revealed a peptide pattern similar to that of the cellular protein. Immunoprecipitation with antibody specific to the -KDEL peptide retention sequence confirmed the presence of this sequence in the secreted protein. Studies of the turnover of disulfide isomerase revealed a half-life of approximately 96 h. Treatment of cells with tunicamycin or heat shock resulted in an increased recovery of newly synthesized disulfide isomerase from cell lysates but diminished recovery from the media. The secretion and cell surface distribution of disulfide isomerase in hepatocytes may be important for the pathogenesis of immune mediated liver injury.

Animals↗
PubMed1995

Copper incorporation into ceruloplasmin in rat livers.

Ceruloplasmin, a blue copper oxidase found in plasma, is synthesized in hepatocytes as a single polypeptide chain consisting of a 19 amino acid leader peptide plus 1046 amino acids of mature protein (132 kDa). Holoceruloplasmin is secreted into the plasma with 6-7 atoms of copper bound per molecule. In this study we identified apo- and holoceruloplasmin and examined the mechanism of copper incorporation during ceruloplasmin biosynthesis using the Long-Evans Cinnamon (LEC) rat which does not incorporate copper into newly synthesized ceruloplasmin. We followed the conversion from ceruloplasmin precursor (with little or no carbohydrate) to the larger product (after carbohydrate addition), which occurred in the secretory compartments of hepatocytes, by native gel electrophoresis. We found that copper accumulates in the hepatocellular Golgi apparatus of LEC rats due to a disorder in the process of copper incorporation. The data indicate that copper is incorporated into ceruloplasmin late in the course of its transport through the secretory compartments.

Animals↗
PubMed1995

Limited value of interictal brain perfusion SPECT for detection of epileptic foci: high resolution SPECT studies in comparison with FDG-PET.

Accurate localization of epileptic foci is important for pre-surgical evaluation of patients with medically intractable epilepsy, and F-18 FDG PET has been proved to be a valuable method for this purpose. To examine the clinical value with interictal brain perfusion SPECT, we performed brain perfusion SPECT of Tc-99m HMPAO by means of a high resolution SPECT camera, and compared the results with F-18 FDG PET images and MRI in 10 patients with medically intractable epilepsy. In 9 of 10 patients (90%), FDG PET images showed focal hypo-metabolism in the area corresponding with the results of electroencephalography (EEG). SPECT images, however, demonstrated hypo-perfused lesions which corresponded with hypo-metabolic lesions on FDG PET images in only 6 cases (60%). Although MRI showed abnormal findings in 8 cases, the lesions were not directly related to epileptic foci in 2 cases. In conclusion, FDG PET is a valuable tool for accurate localization of epileptic foci. Brain perfusion SPECT, however, may not always be paralleled to metabolism visualized on FDG PET images.

Adolescent↗
PubMed1995

Movement-related cortical potentials associated with voluntary muscle relaxation.

We recorded movement-related cortical potentials (MRCPs) associated with voluntary muscle relaxation, which was not accompanied by contraction of the antagonist or any other muscles, in 10 normal subjects. Voluntary, self-paced relaxation of the wrist extensors from the extended position was employed as the relaxation task, and wrist flexion by muscle contraction was employed as the contraction task. The accelerogram was used to obtain the trigger signals for both tasks. The electromyograms of the ipsilateral agonist and antagonist, the proximal muscles and the contralateral corresponding muscles were monitored to confirm the absence of muscle contraction for the relaxation task. All MRCP components were identified in both tasks; Bereitschaftspotential (BP), negative slope (NS'), parietal peak of motor potential (ppMP) and frontal peak of motor potential (fpMP). BP started earlier and was larger at the contralateral parietotemporal electrodes for the relaxation than for the contraction task, and the slow positive shift at the bilateral frontopolar electrodes was seen more often in the relaxation task. It is concluded that the voluntary muscle relaxation needs a cortical preparatory process similar to voluntary muscle contraction, and needs a more extensive and longer preparation process in the primary motor area and possibly in other motor areas as compared with the contraction.

Adult↗
PubMed1995

Peri-rolandic and fronto-parietal components of scalp-recorded giant SEPs in cortical myoclonus.

Scalp topography of giant SEPs to median nerve stimulation was studied in 4 patients with cortical myoclonus of various etiology. The positive peak (P30) at the contralateral parietal area was simultaneously accompanied by a negative peak at the frontal area (N30), and at least one of these two peaks was enhanced in 2 patients. Another positive peak (P25) and a negative peak (N35) were also identified at the peri-rolandic area with different latency from P30 and N30, respectively, in all patients. N35 was enhanced in 3 patients, and P25 in 2 patients. It is concluded that, as seen in normal subjects, tangential (P30-N30) and radial (P25 and N35) components of SEPs are most likely distinguishable in giant SEPs, and that either one or both of those components is enhanced in different ways depending on the patients.

Adolescent↗
PubMed1995

Preparation of recombinant argininosuccinate synthetase and argininosuccinate lyase: expression of the enzymes in rat tissues.

Nitric oxide (NO) is synthesized from arginine by nitric oxide synthase, generating citrulline as another product, which can be recycled to arginine by argininosuccinate synthetase and argininosuccinate lyase. Rat argininosuccinate synthetase was expressed in Escherichia coli as a fusion protein with maltose binding protein, cleaved from binding protein, and purified. The purified synthetase had no enzyme activity. Rat argininosuccinate lyase was expressed in E. coli using pET-3a as a vector, and purified. The purified enzyme had a specific enzyme activity of arginine formation of 2.6 mumol/min/mg protein at 37 degrees C, the value being somewhat lower than those of the enzyme purified from various tissues. Antibodies against these enzymes were produced in rabbits. Immunoblot analyses showed that the two enzymes are most abundant in the liver, followed by kidney and testis. Smaller amounts of the enzyme proteins were present in other tissues. RNA blot analysis showed that the argininosuccinate synthetase mRNA was most abundant in the liver and kidney, followed by testis and other tissues. On the other hand, argininosuccinate lyase mRNA was most abundant in the testis, followed by kidney and liver, and by other tissues. These results show that argininosuccinate synthetase and argininosuccinate lyase are expressed both tissue-specifically and ubiquitously, and that practically all tissues have activities to convert citrulline to arginine.

Animals↗
PubMed1995

Catalytic role of an arginine residue in the highly conserved and unique sequence of phosphoenolpyruvate carboxylase.

Phosphoenolpyruvate carboxylase (PEPC) [EC 4.1.1.31] has a highly conserved and unique sequence, 578-FHGRGGSIGRGGAP-591 (on Escherichia coli, PEPC), in which a GRGG motif is repeated twice with two intervening residues. Since previous chemical modification studies suggested the functional importance of arginine residues, the invariant Arg587 in this region was replaced with Ser, and the enzymatic properties of the resulting mutant enzyme (R587S) were investigated. Replacement led to virtual loss of the catalytic activity to form oxaloacetate. The specific activity was 37 nmol.min-1.mg-1, which corresponds to 2 x 10(-4)-fold the activity of the wild-type enzyme. However, the activity of bicarbonate- and Mg(2+)-dependent hydrolysis of phosphoenolpyruvate (PEP) to pyruvate appeared for the mutant enzyme with a specific activity of 2.1 mumol.min-1.mg-1. In view of the stepwise reaction mechanism proposed for PEPC, this activity can be attributed to impairment of the subsequent partial reaction(s) following the formation of the intermediate carboxyphosphate. The half-saturation concentration (S0.5) of HCO3- in R587S was about 100-fold that in the wild-type enzyme, whereas the respective values for PEP and Mg2+ were 20- and 15-fold, indicative of this residue participating in the binding of HCO3-.

Amino Acid Sequence↗
PubMed1995

Combined intraarterial cisplatin infusion and radiation therapy for invasive bladder cancer.

Combined intraarterial cisplatin infusion and radiation therapy were performed as the initial treatment for 23 patients (mean age: 70 years) with invasive bladder cancers (T2 in 17, T3 in 6) who were suitable for total cystectomy. Of these patients, five who had multiple invasive cancers without laterality had their intrapelvic hemodynamics altered by embolizing a contralateral internal iliac artery. Cisplatin (50 mg) was infused into the internal iliac artery through a subcutaneous reservoir twice a week over three weeks while concurrent radiation therapy with 30 Gy, delivered in 15 fractions, was performed. Additional cisplatin infusions were given in six patients. After this combined therapy, total cystectomy and ileal conduit was performed in six patients and transurethral resection of bladder tumor (TURBT) in 17. Two of the patients who underwent total cystectomy were found to exhibit a complete response. Therefore, the overall response rate was 87%, including 13 complete responses and seven partial responses. The complete response rates in patients with clinical stage T2 and T3 disease were 53 and 67%, respectively. The complete response rate was slightly higher in patients with a non-papillary cancer than in those with a papillary one. Toxic reactions included a decrease in bladder capacity in two patients and severe diarrhea due to methicillin-resistant Staphylococcus aureus colitis in one. Other forms of toxicity, including nausea, vomiting, neurotoxicity in the gluteal region, nephrotoxicity and myelosuppression, were tolerable. All but one of the patients are alive.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

[Incidence of herpes zoster in pediatricians and history of reexposure to varicella-zoster virus in patients with herpes zoster].

We found that pediatricians have enhanced specific cellular immunity to varicella-zoster virus (VZV) compared with the general population, which may be due to reexposure to VZV from children with chickenpox. There have been some reported that the varicella vaccine enhance the specific cellular immunity. To estimate the efficacy of varicella vaccine for protection against herpes zoster in the elderly, we investigated the incidence of herpes zoster in 500 pediatricians and family practitioners with their fifties and sixties, and history of reexposure to VZV in 61 patients with herpes zoster by questionnaires retrospectively. Thirty-four of 352 pediatricians had a past history of herpes zoster. The incidence per 100,000 person-years of herpes zoster was 65.2 in those in their fifties and 158.2 in those in their sixties, which are 1/2 to 1/8 of other reports regarding the general population. Among 61 immunocompetent patients with herpes zoster, only 4 patients (6.6%) had the chance for reexpose to VZV before their herpes zoster. Only 7 (17.5%) of the 40 patients older than 50 years of age lived with their children less than 14 years of age. Twenty-three (57.5%) of them lived without their children and grandchildren. They are thought to be less chance to reexpose to VZV through children. We may think that the booster effect by reexposure to VZV plays an important role to prevent herpes zoster. Therefore, we can speculate that the varicella vaccine may protect against herpes zoster in the elderly by the enhanced specific cellular immunity due to the booster effect.

Adolescent↗
PubMed1995

Inhibitory activity in saliva of cell-to-cell transmission of human T-cell lymphotropic virus type 1 in vitro: evaluation of saliva as an alternative source of transmission.

Human T-cell lymphotropic virus type 1 (HTLV-1) is known to be transmitted vertically through breastfeeding and horizontally by blood transfusion and sexual contact. Our intervention study has suggested the presence of additional alternative maternal transmission pathways. To explore the possibility of transmission through saliva, we used PCR to quantify the HTLV-1 provirus in saliva samples from 18 carrier mothers and 10 patients with HTLV-1-associated myelopathy/tropical spastic paraparesis. The provirus was detected in 60 and 90%, respectively, of the samples, with estimated copy numbers in the range of 10 to 10(4)/ml. However, the saliva, regardless of the presence or absence of antibodies to the virus, showed a strong tendency to inhibit the cell-to-cell transmission of HTLV-1 in vitro, as examined by a syncytium inhibition assay. The natural inhibitory activity in saliva of seronegative volunteers was heat sensitive, and most of the activity was recovered by ultrafiltration in the fraction of macromolecules with a molecular weight of more than 100,000. In addition to this natural activity, saliva of HTLV-1-infected individuals contained immunoglobulin G molecules capable of neutralizing syncytium formation. These results strongly suggested that HTLV-1-infected cells in the carriers' saliva, which contains neutralizing antibodies in addition to the natural activity inhibiting cell-to-cell viral infection, barely transmit the virus. Transmission of HTLV-1 through the saliva would thus seem to be rare, if it occurs at all.

Adult↗
PubMed1995

Role of heat shock cognate 70 protein in import of ornithine transcarbamylase precursor into mammalian mitochondria.

The roles of the 70-kDa cytosolic heat shock protein (hsp70) in import of precursor proteins into the mitochondria were postulated to be related to (i) unfolding of precursor proteins in the cytosol, (ii) maintenance of the import-competent state, and (iii) unfolding and transport of precursor proteins through contact sites, in cooperation with matrix hsp70. We examined roles of cytosolic hsp70 family members in import of ornithine transcarbamylase precursor (pOTC) into rat liver mitochondria, using an in vitro import system and antibodies against hsp70. Immunoblot analysis using an hsc70 (70-kDa heat shock cognate protein)-specific monoclonal antibody and a polyclonal antibody that reacts with both hsc70 and hsp70 showed that hsc70 is the only or major form of hsp70 family members in the rabbit reticulocyte lysate. The hsc70 antibody did not inhibit pOTC import when added prior to import assay. However, when pOTC was synthesized in the presence of the antibody and then subjected to import assay, pOTC import was markedly decreased. pOTC import was also decreased when the precursor was synthesized in the lysate depleted for hsc70 by treatment with hsc70 antibody-conjugated Sepharose. This reduction was almost completely restored by readdition of purified mouse hsc70 during pOTC synthesis. The readdition of hsc70 after pOTC synthesis and only during the import assay was not effective. Thus, once import competence of pOTC was lost, hsc70 was ineffective for restoration. Newly synthesized pOTC lost import competence in the absence of hsc70 somewhat more rapidly than in its presence. These results indicate that hsc70 is required during pOTC synthesis and not during import into the mitochondria. hsc70 presumably binds to pOTC polypeptide and maintains it in an import-competent form.

Animals↗
PubMed1995

Reactivation of chickenpox contracted in infancy.

Varicella zoster virus DNA in mononuclear cells was studied by the polymerase chain reaction to obtain virological evidence of reactivation in the children who had contracted chickenpox in infancy. The results appear to explain why chickenpox in infancy is a risk factor for herpes zoster in immunocompetent children.

Adolescent↗
PubMed1995

Presence of Bereitschaftspotential preceding psychogenic myoclonus: clinical application of jerk-locked back averaging.

The method of jerk-locked back averaging was applied to six patients with clinically diagnosed psychogenic myoclonus. Five patients had a slow negative EEG shift corresponding to Bereitschaftspotential at the central region starting 0.7 to 2.1 seconds before the onset of the myoclonic jerk. One patient had no potential preceding the myoclonic jerk, whereas a small negative potential preceded the voluntary movement mimicking the jerk. The demonstration of Bereitschaftspotential before an apparently involuntary myoclonic jerk helps the clinical diagnosis of psychogenic myoclonus, although the absence of Bereitschaftspotential does not necessarily indicate that the movement is involuntary. Jerk-locked back averaging is clinically useful as a specific laboratory examination in this condition.

Adult↗
PubMed1995

Biosynthesis of acetylenic compounds in cultured cells of Asparagus officinalis from [1-13C]- and [U-13C] Glucose.

The biosynthetic pathway of phenolics with an acetylenic group, 4-[5-(4-methoxyphenoxy)-3-penten-1-ynyl]phenol (1) and its related compounds, isolated from suspension-cultured cells of Asparagus officinalis L. (Liliaceae), was studied in feeding experiments using [1-13C]- and [U-13C] glucose. Analyses of the 13C-NMR spectra of the methyl ether and acetate of the 13C-labelled species of 1 indicated that the aromatic rings at both ends of the molecule are formed from shikimic acid. It was also assumed that the acetylenic carbons in the C5 chain could be incorporated together with its adjacent aromatic ring through any phenethyl class compound derived from phenylpropanoids, and the propenylene carbon through glycolysis metabolites with C3 carbon units.

Acetylation↗
PubMed1995

Acetylenic compounds isolated from cultured cells of Asparagus officinalis.

Three new acetylenic compounds, compounds I, II and III were isolated from the cultured cells of Asparagus officinalis L. (Liliaceae) and their structures identified as 1-methoxy-4-[5-(4-methoxyphenoxy)-3-penten-1-ynyl]-benzene, 4-[5-(4-methoxyphenoxy)-3-penten-1-ynyl]phenol and 4-[5-(4-hydroxyphenoxy)-3-penten-1-ynyl]phenol, respectively, from chemical and spectral analysis.

Acetylation↗
PubMed1995

Combined intraarterial cisplatin infusion and radiation therapy for invasive bladder cancer.

Combined intraarterial cisplatin infusion and radiation therapy were performed as the initial treatment for 23 patients (mean age: 70 years) with invasive bladder cancers (T2 in 17, T3 in 6) who were suitable for total cystectomy. Of these patients, five who had multiple invasive cancers without laterality had their intrapelvic hemodynamics altered by embolizing a contralateral internal iliac artery. Cisplatin (50 mg) was infused into the internal iliac artery through a subcutaneous reservoir twice a week over three weeks while concurrent radiation therapy with 30 Gy, delivered in 15 fractions, was performed. Additional cisplatin infusions were given in six patients. After this combined therapy, total cystectomy and ileal conduit was performed in six patients and transurethral resection of bladder tumor (TURBT) in 17. Two of the patients who underwent total cystectomy were found to exhibit a complete response. Therefore, the overall response rate was 87%, including 13 complete responses and seven partial responses. The complete response rates in patients with clinical stage T2 and T3 disease were 53 and 67%, respectively. The complete response rate was slightly higher in patients with a non-papillary cancer than in those with a papillary one. Toxic reactions included a decrease in bladder capacity in two patients and severe diarrhea due to methicillin-resistant Staphylococcus aureus colitis in one. Other forms of toxicity, including nausea, vomiting, neurotoxicity in the gluteal region, nephrotoxicity and myelosuppression, were tolerable. All but one of the patients are alive. This patient died of distant metastasis and seven other patients had a local recurrence of bladder cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

[Perinodal cryomodification for supraventricular tachycardia].

The perinodal cryomodification procedure ablates the surrounding tissue of atrioventricular node, as a consequence, eliminates atrioventricular nodal reentrant tachycardia (AVNRT) and reduces the ventricular response during atrial fibrillation. We performed the procedure in 4 patients: 2 patients with AVNRT, 1 patient with atrioventricular reciprocating tachycardia utilizing a left side accessory pathway and atrioventricular node dual pathways, and 1 patient with tachycardic atrial fibrillation. The concomitant procedures include a closure of atrial septal defect and a mitral valve replacement. All the patients survived the procedure and cured the tachycardia. Post operative electrophysiological studies showed that the retrograde conduction over the atrioventricular node was eliminated while the antegrade conduction was preserved in the patients with atrioventricular node dual pathways. The perinodal cryomodification is a safe and effective procedure to cure the tachycardia, particularly in the patients with a structural heart disease.

Adult↗