Biomedical subjects

K Kuroda

Publications and source records attributed to K Kuroda.

At least 127 records · Page 7Linked to original sources

PubMed1998

Citrate promotes attachment of Prevotella nigrescens (intermedia) ATCC 25261 to hydroxyapatite.

Large quantities of Prevotella nigrescens (intermedia) ATCC 25261 (P. nigrescens) cells adhere to hydroxyapatite (HA) treated with citrate, but do not adhere experimental pellicle prepared from human whole saliva. To determine the nature of the citrate responsible for promoting P. nigrescens cell adhesion, the duration and frequency of citrate treatment of HA and the inhibitory effect of other carboxylates were tested. The citrate rapidly adhered to HA beads in less than 15 min. With a lower concentration (0.4 mM) of citrate, four treatments of HA were required to promote the maximum adherence to P. nigrescens cells. Citrate-enhanced P. nigrescens cell adherence to HA beads was also inhibited in the presence of cis-aconitate, oxaloacetate and oxalsuccinate. It was also found that P. nigrescens cells heated to 65 degrees C or higher for 5 min could no longer become attached to citrate-treated HA. These data suggest that citrate is one of the essential factors responsible for P. nigrescens cell attachment to apatitic surfaces, and that P. nigrescens' adhesion to citrate is extremely heat-sensitive.

Aconitic Acid↗

PubMed1998

[Normal term delivery after adrenalectomy for Cushing syndrome in a pregnant patient--a case report].

This is a case of a 29-year-old female. She visited our hospital with the chief complaint of swelling of the legs and abdominal bloating at the 10th week of pregnancy. Edema and central obesity were observed in the lower extremities. Hematological and biochemical tests revealed hypokalemia. Gynecologically, she was normal. Elevated blood cortisol levels were identified on the hormonal tests, which suggested the existence of Cushing's syndrome. Ultrasound revealed the presence of a tumor in the left adrenal gland, and she was referred to our department for surgery. On September 13, 1994, left adrenalectomy was performed in a right lateral position under inhalation anesthesia and epidural anesthesia. Adjuvand steroid therapy was initiated during surgery and the blood cortisol levels were normalized within 2 months. She delivered a baby girl weighing 2,722 g at the 40th week of pregnancy via a normal transvaginal delivery. Pregnancy rarely occurs in patients with Cushing's syndrome. We think she was the first case in Japan who had normal 40th week transvaginal delivery after adrenalectomy during pregnancy. We present a description of our case here with reference to the relevant literature.

Adrenalectomy↗

PubMed1998

[Bickerstaff's brainstem encephalitis with one-and-a-half syndrome].

We presented a case of Bickerstaff's brainstem encephalitis. A 50-year-old woman developed semicoma, external ophthalmoplegia, hyporeflexia, extensor plantar responses. A high titer of anti-GQ1b IgG antibody was detected in her acute phase serum. Auditory brainstem response suggested the presence of brainstem lesion. Although MRI and CSF showed no abnormality, one-and-a-half syndrome was observed during the clinical course, suggesting involvement of the pontine tegmentum. She received steroid pulse-therapy and symptoms disappeared completely. Our case suggested that anti-GQ1b IgG antibody might relate to the pathogenesis of intramedullary as well as extramedullary lesions.

Biomarkers↗

PubMed1998

[Effects of excitatory sulfur amino acids on glutamate transport in synaptosomes isolated from the rat cerebral cortex].

Transport of glutamate, the disturbance of which has been implicated in amyotrophic lateral sclerosis (ALS), may be influenced by various substances. Excitatory sulfur amino acids (SAAs) could be increased in ALS, because the elevation of taurine, the final product of the metabolic pathway of SAAs, has been reported in this intractable disease. I examined effects of excitatory SAAs on the transport of glutamate in synaptosomes. Synaptosome fractions were prepared by discontinuous density-gradient centrifugation from the rat cerebral cortex, and were incubated at 35 degrees C with varying concentrations of L-[3H] glutamate in the absence or presence of excitatory SAAs; cysteine sulfinic acid (CSA), cysteic acid (CA), homocysteine sulfinic acid (HCSA), homocysteic acid (HCA) and S-sulfocysteine (SC). Kinetic characterization of uptake confirmed the high-affinity nature of the transport system, the Michaelis constant (Km) for glutamate uptake being 10 microM. The nature of inhibition was competitive. Potent inhibition of transport was exhibited by CSA and CA, whereas substantially weaker inhibitory effects were exhibited by HCSA, and almost no effects by HCA or SC. Inhibition by excitatory SAAs, especially CSA and CA of the high-affinity glutamate transporter may be involved in the pathogenesis of ALS.

ATP-Binding Cassette Transporters↗

PubMed1998

[Short-term intravesical instillation of pirarubicin (THP) in prophylactic treatment after transurethral resection of superficial bladder tumor].

We conducted a prospective randomized controlled study on the prophylactic effects of short-term intravesical instillation of pirarubicin (THP) against recurrence to determine the effective administration schedule. All patients gave their informed consent. The subjects included bladder cancer patients who had pTa or pT1, and G1 or G2 cancer, and became tumor-free after transurethral resection of the bladder tumor (TUR-BT). After dissolving 30 mg of THP into 5 ml of distilled water, physiological saline was added to adjust the total volume to 50 ml, which was then instilled into the bladder, and was retained for 5 minutes. The schedule of instillation was for daily for 7 consecutive days from the day of TUR-BT and subsequently once a week for 10 weeks, 17 times in total for Group I, and once every two weeks for 6 months (12 times) starting 2 weeks after TUR and subsequently once a month until one year had passed after surgery (6 times), 18 times in total for Group II. The total number of cases was 69 (36 in Group I, 33 in Group II). The tumor-free ratios determined by the Kaplan-Meier analysis were 93.9% in Group I and 72.7% in Group II for one year, and 86.8% in Group I and 59.5% in Group II for two years. There was a statistically significant difference in the tumor-free ratios between the two groups by the generalized Wilcoxon test and the Log rank test (p = 0.0145 and 0.0107, respectively). Multivariated analysis using Cox's comparison hazard model produced p-values of 0.0002, 0.0007, 0.0009 and 0.0040 in the order of therapeutic mode, initial onset/recurrence, stage and number of tumor. Adverse events that forced discontinuation of the therapy for a while occurred in 4.3%. These results demonstrated that short-term intensive intravesical instillation of THP immediately after TUR-BT was a safe and effective therapy.

Administration, Intravesical↗

PubMed1998

[A case of spastic paraparesis with mental deterioration and markedly thin corpus callosum--callosal dysfunction demonstrated by magnetic stimulation].

We have studied function of the corpus callosum in a patient with spastic paraparesis with mental deterioration and markedly thin corpus callosum using magnetic stimulation methods. In a 21-year-old woman with slowly progressive gait disturbance, neurological examination showed mental deterioration, euphoria, spastic paraparesis, bilateral Babinski's sign, and hyperesthesia caudal to the eighth thoracic level. No abnormalities were observed in electroencephalograms. Magnetic resonance imaging (MRI) studies of the brain showed cerebral cortical atrophy, markedly thin corpus callosum, and dilated cavum septum pellucidum and cavum Vergae, but spinal cord MRIs showed no abnormalities. The lysosomal enzyme activities, whose reduction was known to cause leukodystrophy, were all normal. Very long chain fatty acid was not increased in her blood, which is against adrenoleukodystrophy. She had no anti-HTLV-1 virus antibody. Based on these clinical features and the results of biochemical analyses, we diagnosed this patient as having spastic paraplegia associated with hypoplasia of the corpus callosum (Nojima and Iwabuchi). We performed three studies on the central motor pathways in this patient. The latencies of responses recorded from upper or lower limb muscles were all within the normal range, despite that the thresholds were slightly increased. This suggests that axonal degeneration occurs in the central motor pathways, which is consistent with the autopsy findings of a patient with hereditary spastic paraplegia associated with hypoplasia of the corpus callosum. Connection between the bilateral motor cortices was investigated by magnetic stimulation of both motor cortices. The suppression of the motor cortex evoked by stimulation of the contralateral motor cortex through the corpus callosum was absent in this patient. Intracortical inhibition within the motor cortex was demonstrated to be normal by a paired-magnetic stimulation technique. Based on the results of these results of these two experiments, we conclude that the function of the corpus callosum was disturbed in the present patient. This report first shows the functional abnormality of the extremely thin corpus callosum in a patient with hereditary spastic paraplegia associated with hypoplasia of the corpus callosum.

Adult↗

PubMed1998

[Analysis of the factors involving in the success or failure of home infusion therapy (HIT)].

A survey was conducted from April through September, 1997, of 24 hospitalized terminal lung cancer patients connected to IVH and CSC, for whom the possibility of release from hospital was considered, and of their families. A comparative survey was made between patients who accepted HIT and those who did not. No difference was found between the groups by age, sex, or disease stage, nor was there a difference in physical symptoms such as pain and respiratory difficulty. However, the percentage of patients who were told the name of their disease was significantly higher in the group switched to HIT, 3 of whom were even given prognoses. There was no difference in the percentage of patients who lived with their families, although there was a higher percentage in the HIT group whose spouses also lived with the family. Nineteen of the 24 patients wished to return home, but 8 of those patients were not released from hospital for such reasons as the patient not wanting to be a burden on his or her family or the family's lack of ability to provide care. It was found that important factors in urging home care for the terminal cancer patient were whether or not the patient was told the name of his or her disease, and whether or not the patient lived with a healthy spouse.

Aged↗

PubMed1997

Influence of retinoic acid on the differentiation pathway of T cells in the thymus.

This study investigated the ability of retinoic acid (RA) to influence T cell differentiation. All-trans-RA had marked effects on T cell differentiation in murine fetal thymic organ cultures (FTOCs). The time course of the effect of all-trans-RA in FTOC of day 14 C57BL/6 embryos revealed a twofold increase in the frequency of CD4 single-positive (SP) cells and a high level of CD3-bearing cells (CD3high cells) at a later stage of T cell development. At an earlier stage, all-trans-RA induced a twofold increase in the frequency of CD4 SP cells, but significantly suppressed the upregulation of CD3 and TCR. Reverse transcription-PCR using RA receptor (RAR) subtype-specific primers showed that RAR alpha but not beta and gamma is expressed during T cell development in the thymus and that its expression was associated with the generation of CD4/CD8 double-positive (DP) cells. In FTOC of day 16 BALB/c embryos, the level of V beta 3high cells was greatly reduced (1.4% of the CD3high cells) in response to the mouse mammary tumor virus-6-encoded superantigen, but V beta 3-bearing cells were rescued from the deletion in the presence of all-trans-RA (5.6% of the CD3high cells). Further, the inhibitory effect of all-trans-RA on thymocyte deletion was observed when the deletion was induced by a low concentration of staphylococcal enterotoxin B in FTOC. Taken together, these data suggest that RA increases the frequency of mature and self-reactive T cells in the thymus, possibly by inhibiting the process of negative selection at the DP stage of T cell differentiation.

Animals↗

PubMed1997

Induction of ubiquitin conjugating enzyme activity for degradation of topoisomerase II alpha during adenovirus E1A-induced apoptosis.

Topoisomerase (topo) II alpha is degraded via polyubiquitination during adenovirus E1A-induced apoptosis in MA1 cells, a derivative of the human epidermoid carcinoma cell line KB. Topo II alpha ubiquitination activity in MA1 cells increased nearly 10-fold after induction of E1A in response to dexamethasone. To identify a topo II alpha ubiquitination factor(s), the S100 fractions prepared from apoptosis-induced (42 h) and uninduced (0 h) MA1 cells were first fractionated by ubiquitin-Sepharose columns. The ubiquitination activity induced by E1A was predominantly eluted with 20 mM AMP. Further fractionation of the AMP eluates on Resource-Q columns and the thiolester formation of the proteins resolved by electrophoresis with biotinylated ubiquitin revealed that a species of E2 isozyme recovered in the QFT2 fraction increased markedly in MA1 cells after E1A expression. These results indicate that a ubiquitination factor(s) specific to topo II alpha is induced during E1A-induced apoptosis in MA1 cells.

Adenovirus E1A Proteins↗

PubMed1997

Anti-beta2-glycoprotein I (beta2GPI) monoclonal antibodies with lupus anticoagulant-like activity enhance the beta2GPI binding to phospholipids.

beta2-Glycoprotein I (beta2GPI), a plasma glycoprotein with phospholipid-binding property, is known to be the actual target antigen for autoimmune type anticardiolipin antibodies (aCLs). Certain groups of aCLs (anti-beta2GPI antibodies) exert lupus anticoagulant (LA) activity and perturb the function of vascular endothelial cells. This investigation aimed at highlighting some insights into the molecular basis by which aCLs exert their biological effects by using anti-beta2GPI mAbs with well-characterized epitopes from mice and from patients with antiphospholipid syndrome. Anti-beta2GPI mAbs directed against the third domain (Cof-20 and Cof-22) and fourth domain (Cof-21, EY1C8, and EY2C9) of beta2GPI inhibited the thrombin generation induced by Russell's viper venom in diluted plasma and that induced by the prothrombinase complex reconstituted with purified clotting factors. This anticoagulant activity was abrogated in the presence of an excess amount of phospholipids, thus resembling the LA activity. In stark contrast, anti-beta2GPI mAbs directed against the fifth domain and the carboxy-terminal region of the fourth domain showed no LA-like activity. These findings suggest that the LA activity of anti-beta2GPI antibodies depends on their epitope specificity. Experiments carried out to clarify the mechanism of the LA activity showed that anti-beta2GPI mAbs with LA-like activity, but not those without this effect, enhance the beta2GPI binding to phospholipids. In addition, the F(ab')2 fragment, but not the Fab' fragment, of the anti-beta2GPI mAbs was found to enhance the LA activity and the beta2GPI binding to phospholipids, suggesting that anti-beta2GPI antibodies induce formation of multiple complexes of beta2GPI on the surface of phospholipids because of their bivalent property. This clustering of beta2GPI molecules induced by anti-beta2GPI antibodies, probably because of their multivalent property and epitope specificity, might hinder the lateral mobility and activation of clotting factors on the surface of phospholipids and thus exert LA activity. Clustering of beta2GPI molecules may also explain the molecular mechanism by which anti-beta2GPI antibodies alter the function of leukocytes and endothelial cells. The well-documented heterogeneous LA activity of aCLs (anti-beta2GPI antibodies) may also be explained by their epitope specificity.

Animals↗

PubMed1997

DNA polymerase epsilon from Drosophila melanogaster.

We identified a DNA polymerase species in Drosophila melanogaster embryos, and purified it. This polymerase shared some common properties with DNA polymerase epsilon from mammals and yeast as follows; it has a preference for poly(dA)/oligo(dT) as a template/primer, it is highly processive in DNA synthesis, it co-fractionates with 3'-5' exonuclease activity, it is sensitive to aphidicolin and is resistance to ddTTP. The polymerase activity was inhibited in the immuno-precipitation assay with anti-pol-epsilon antibodies, which were produced against a polypeptide coded on the cDNA of a putative Drosophila pol-epsilon we isolated previously. Using these antibodies, Western blot analysis revealed that this polymerase is a 250kDa polypeptide, which is the same size as observed in mammals and yeast. These results indicate that Drosophila produces the epsilon-class of DNA polymerase, and like mammals or yeast, possesses the 5 typical classes of DNA polymerases (alpha to epsilon) in its embryos.

Animals↗

PubMed1997

Temperature mapping using the water proton chemical shift: a chemical shift selective phase mapping method.

A proton-chemical-shift-based temperature imaging method, called chemical shift selective phase mapping, is proposed. The technique uses frequency-selective suppression to provide frequency selectivity to the phase mapping method. Separate imaging of the phase distributions of the water and nonwater signals reduced the error due to the presence of a nonwater signal in measuring the water proton chemical shift change in two-component samples. Imaging of the phase difference between water and oil yielded an internally referenced water proton chemical shift measurement to visualize the temperature change distribution, which was unaffected by motion-induced susceptibility changes.

Animals↗

PubMed1997

Fibrinolytic activity in the CSF and blood following subarachnoid haemorrhage.

Fibrinolytic agents are administered to resolve subarachnoid clot, a major reservoir for spasmogen, to prevent delayed cerebral vasospasm (VS) in patients with subarachnoid haemorrhage (SAH). However, intracranial bleeding often occurs, which may be caused by over-activation of fibrinolysis in the cerebrospinal fluid (CSF) milieu. We measured the levels of D dimer in the CSF and blood of patients with SAH to analyse the correlation between fibrinolytic activity and VS. CSF and blood samples were obtained three times, and VS was identified by angiography. The levels of D dimer in the CSF were significantly higher than in the blood, but changes with time were inverse. Patients with VS showed significantly lower levels of D dimer in both CSF and blood in the initial stage compared to those without VS. These observations suggest that monitoring of fibrinolytic activity in the CSF to identify patients eligible for additional fibrinolytic treatment could reduce the risk of VS and iatrogenic intracranial bleeding.

Adult↗

PubMed1997

Metabolites of arsenic induced tetraploids and mitotic arrest in cultured cells.

The toxic effects of arsenic compounds on cell divisionwere studied, using Chinese hamster V79 cells. Seven arsenic compounds weretested. Inorganic arsenic compounds (arsenite and arsenate), which have beenfound in drinking water, inhibited cell growth at very low concentrations. Monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and trimethylarsineoxide (TMAO), which are methylated metabolites of inorganic arsenics, wereless cytotoxic than the inorganic arsenics themselves. The cytotoxicity ofthe three methylated metabolites decreased as the number of methyl groupsincreased. Arsenobetaine (AsBe) and arsenocholine (AsC), which have beenfound in some marine products, did not show any cytotoxicity. Threemethylated metabolites; MMA, DMA and TMAO induced mitotic arrest. Tetraploidyproduction was observed in cells exposed to DMA or TMAO. Arsenite, arsenate,AsBe and AsC did not induce mitotic arrest or tetraploids. These resultssuggest that MMA, DMA and TMAO exert some effect on cell division inmetaphase and may thereby give some clue as to the carcinogenic mechanism ofarsenic.

Animals↗

PubMed1997

The urinary excretion of arsenic metabolites after a single oral administration of dimethylarsinic acid to rats.

The biotransformation following oral administration of dimethylarsinic acid (DMA), an organoarsenical herbicide and the main metabolite of inorganic arsenic in mammals, was studied in rats. Male F344/DuCrj rats were administered a single dose of DMA (50 mg/kg) orally. Urine was collected at 0, 2, 4, 8, 10, 24, and 48 h after administration by forced urination. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS). The proportions of urinary elimination of DMA, trimethylarsine oxide (TMAO), methylarsonic acid (MMA), an unidentified arsenic metabolite, and arsenite were determined at various timepoints after administration. Unmetabolized DMA was the most common form excreted during the first 4 h. Thereafter, a gradual decrease in the proportion of DMA was observed, while progressive increases in those of TMAO, the unidentified metabolite, and arsenite occurred. The proportion of TMAO excreted amounted to over 50% of all arsenic in urine between 6 and 24 h. The proportion of the unidentified metabolite and arsenite were each approximately 10% at 10 and 24 h after administration. The findings indicate that DMA administered to rats was initially excreted as unchanged DMA, and later as the methylated metabolite, TMAO. Arsenite, a demethylated metabolite of DMA, also was excreted later than elimination of DMA and TMAO. The hypothesis of demethylation by intestinal microorganisms can be supported by comparing the metabolites following oral and intraperitoneal administration. The unidentified metabolite was readily decomposed by HCl but was left unchanged by NaOH; these findings suggest that it was present in a complexed form in urine.

Administration, Oral↗

PubMed1997

Downregulation of decorin expression in dermal fibroblasts by interleukin-4.

Decorin, a chondroitin/dermatan sulphate proteoglycan, plays an important role in the assembly of extracellular matrix components. In this study, we investigated the influence of interleukin-4 (IL-4) on the expression of decorin and sulphated glycosamino-glycans (GAGs) in cultures of human skin fibroblasts. IL-4 inhibited the expression of decorin mRNA and its core protein synthesis. IL-4 stimulated dermatan sulphate but decreased chondroitin sulphate synthesis without altering the total amount of sulphated GAGs. IL-4 had no effect on the initiation activity of the dermatan sulphate and chondroitin sulphate chains, as evaluated by the effect of exogenous beta-xyloside that acts as an artificial chain initiator for dermatan sulphate and chondroitin sulphate biosynthesis. Type I collagen mRNA levels and protein synthesis were increased by this IL-4. Therefore, the effects of IL-4 on decorin and GAGs as well as type I collagen may have important implications for wound healing and for the treatment of several fibrosing diseases.

Adult↗

PubMed1997

Decorin and glycosaminoglycan synthesis in skin fibroblasts from patients with systemic sclerosis.

We investigated the expression of decorin and the synthesis of sulphated glycosaminoglycans (GAGs) in cultured fibroblasts from patients with early-stage systemic sclerosis (SSc). Decorin mRNA levels were 1.8-fold higher in SSc fibroblasts than in control fibroblasts. SSc fibroblasts also produced 2.3-fold more decorin core protein and 2.2-fold more sulphated GAGs including dermatan sulphate and chondroitin sulphate. Newly synthesized GAGs, in the presence of p-nitrophenyl beta-xylopyranoside, which elongates dermatan sulphate and chondroitin sulphate as an initiator, were increased tenfold and were mainly composed of dermatan sulphate and chondroitin sulphate. The rate of stimulation by the beta-xyloside was similar in SSc and control fibroblasts. These results suggest that the increased amount of dermatan/chondroitin sulphate in SSc fibroblasts reflects an enhanced expression of decorin core protein. Type I collagen mRNA levels in SSc fibroblasts were also increased together with its synthesis. Therefore, our results indicate that an altered decorin and collagen production may affect the organization of collagen fibres and the fibrotic process observed in patients with SSc.

Adult↗

PubMed1997

Gene expression of types I and III collagen, decorin, matrix metalloproteinases and tissue inhibitors of metalloproteinases in skin fibroblasts from patients with systemic sclerosis.

Cultured fibroblasts from patients with systemic sclerosis (SSc) and normal individuals were examined for gene expression of types I and III collagen, decorin, matrix metalloproteinases (MMP) MMP-1, MMP-2, and MMP-3, tissue inhibitors of metalloproteinases (TIMP) TIMP-1 and TIMP-2, urokinase- and tissue-type plasminogen activators (u-PA and t-PA). Fibroblasts from patients with early stage SSC (less than 1 year duration of disease) exhibited higher levels of types I and III procollagen, decorin, MMP-1, MMP-3, TIMP-1, and PAs than those from normal individuals. The gene expression of procollagen alpha 1(I) and TIMP-1 mRNAs were increased, but those of decorin, MMP-1, MMP-2, and MMP-3 were decreased, in fibroblasts from SSc patients with mid-stage SSc (2 to 4 years duration) as compared with those from normal individuals. In contrast, no significant difference in gene expression was found between fibroblasts from normal individuals and from patients with late-stage SSc (more than 6 years duration). These results suggest that gene expression of collagen, decorin, and degrading factors is dynamically modulated during fibrillogenesis. The responses of procollagen alpha 1(I) mRNA to IL-1 and TGF-beta were lower in fibroblasts from SSc patients with early and mid-stage disease, but not in those from patients with-late stage disease, than in control fibroblasts, which indicates that these cytokines may be involved in the earlier phases of fibrosis in SSc.

Adult↗