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Biomedical subjects

R Iizuka

Publications and source records attributed to R Iizuka.

At least 19 recordsLinked to original sources
PubMed2001

Glycine at the 65th position plays an essential role in ATP-dependent protein folding by Archael group II chaperonin.

In the previous study, we have found that G65C and I125T double mutant of alpha chaperonin homo-oligomer from a hyperthermophilic archaeum, Thermococcus sp. strain KS-1, lacks ATP-dependent protein refolding activity despite showing ATPase activity and the ability to bind the denatured proteins. In this study, we have characterized several mutant Thermococcus chaperonin homo-oligomers with the amino acid substitutions of Gly-65 or Ile-125. The results showed that amino acid residue at 65th position should be a small amino acid such as glycine or alanine for the ATP-dependent refolding activity. The alpha chaperonin homo-oligomers with amino acid substitution of Gly-65 by amino acids whose side chains are larger than the methyl group did not have ATP-dependent protein refolding activity, but exhibited an increase of the binding affinity for unfolded proteins in the presence of ATP or AMP-PNP. (c)2001 Elsevier Science.

Adenosine Triphosphatases↗
PubMed2001

Determination of serotonin in microdialysis samples from rat brain by microbore column liquid chromatography with post-column derivatization and fluorescence detection.

The present paper describes a new method for on-line determination of 5-HT in brain microdialysates from awake rats by microbore column liquid chromatography with post-column derivatization and fluorescence detection. The derivatization reagent contained 1 mM benzylamine and 0.5 mM potassium hexacyanoferrate (III), both dissolved in a mixture of acetonitrile and 25 mM borate buffer (pH 11.0) (1:1, v/v). The limit of detection (S/N=3) for 5-HT was 0.5 fmol/20 microl. The samples were injected every 20 min onto a microbore column packed with C18 silica gel. The method exhibits an excellent stability over the periods of at least 12-24 h. The basal levels of 5-HT from 25 awake rats were 7.10+/-1.06 fmol/20 microl in the dorsal hippocampus and 4.64+/-0.91 fmol/20 microl (mean+/-SD) in the striatum. The 5-HT release increased to about 1500% during the perfusion with 100 mM K(+) containing Ringer solution or it was reduced to 60 or 40% during the perfusion with 1 microM tetrodotoxin or calcium free Ringer, respectively. The new method can be used to monitor extracellular 5-HT following acute systemic drug administration.

Animals↗
PubMed2001

[Activities of thymidylate synthase and dihydropyrimidine dehydrogenase in patients with colorectal cancer].

Between 1998 and 2001, 82 colorectal cancers were resected in our hospital. The activities of TS and DPD were evaluated. TS activities in tumor tissues were significantly higher than in normal tissue, but the DPD activities had no significant difference between them. TS and DPD showed a correlation between normal and tumor tissues in stage III or IV patients. The TS value of patients with recurrence tended to be higher than that of patients with no recurrence. Especially in stage I or II patients with recurrence, who were administered 5-FU before recurrence, the TS value was significantly higher than in non-treated patients. In stage III or IV patients, it was considered that DPD prevention was important for 5-FU to effectively prevent TS. The TS value might be a new prospective risk factor for recurrence. Moreover, TS and DPD would be the index of biological malignancy.

Adult↗
PubMed2000

4-Dimethylaminobenzylamine as a sensitive chemiluminescence derivatization reagent for 5-hydroxyindoles and its application to their quantification in human platelet-poor plasma.

A selective and sensitive high-performance liquid chromatographic method with chemiluminescence detection for the determination of 5-hydroxyindoles is described, based on the reaction of 5-hydroxyindoles with 4-dimethylaminobenzylamine. Serotonin, 5-hydroxyindole-3-acetic acid, 5-hydroxytryptophol, 5-hydroxyindole-3-acetamide and N-acetyl-5-hydroxytryptamine were used as model compounds to optimize the derivatization and chemiluminescent reaction. The reagent reacts with 5-hydroxyindoles in slightly alkaline media in the presence of potassium hexacyanoferrate(III) to give the corresponding derivatives, which can be separated on a reversed-phase column, Wakosil-II 5C18RS, with aqueous acetonitrile as an eluent. The derivatives were detected by peroxyoxalate chemiluminescence detection. The detection limits are in the range of 0.5-1.2 fmol per 100-microl injection. The method was applied to the simultaneous determination of serotonin and 5-hydroxyindole-3-acetic acid in human platelet-poor plasma.

Aniline Compounds↗
PubMed1999

Borna disease virus infection in domestic cats: evaluation by RNA and antibody detection.

Borna disease virus (BDV) infection has been suggested to cause spontaneous neurological disease in cats referred to as staggering disease. However the evaluation of BDV infection in neurologically asymptomatic cats remained unclear. In the present study, BDV infected, asymptomatic cats in Tokyo were surveyed both by the presence of plasma antibodies against BDV-p24 and -p40 and by RNA detection in peripheral blood mononuclear cells. Seven of 32 domestic cats (21.9%) were serologically or genetically judged to be BDV-infected. Six cats were positive for anti-BDV antibody and two cats were positive for BDV RNA. Within the 2 RNA-positive cats, only one was positive for anti-BDV antibodies. Furthermore, the findings of anti-BDV-p40 and anti-BDV-p24 antibody-positive cats did not completely overlap. These results suggest that there are neurologically asymptomatic domestic cats infected with BDV present in the Tokyo area.

Animals↗
PubMed1996

Monocytic differentiation modulates apoptotic response to cytotoxic anti-Fas antibody and tumor necrosis factor alpha in human monoblast U937 cells.

Interferon-gamma (IFN-gamma), vitamin D3 (VD), and retinoic acid (RA) induce differentiation of human monoblastic leukemia U937 cells to macrophage-like cells with potential superoxide anion-generating activity upon further stimulation. Here we report that U937 cells thus differentiated show various responses to apoptotic induction with a cytotoxic anti-Fas antibody and tumor necrosis factor (TNF). VD-or RA-treated U937 cells acquired resistance against Fas- or TNF receptor (TNFR)-mediated apoptosis, whereas apoptotic cell death was accelerated in IFN-gamma-treated cells. By flow cytometric analyses, no decrease in expression of surface Fas antigen or p55 TNFR was observed in differentiated U937 cells. Cell surface expression of CD11b was seen only when differentiation was induced with VD or RA but not with IFN-gamma. The growth of VD- or RA-treated cells was retarded but IFN-gamma-treated cells were prolific. These findings suggest that the differentiation state differs with the inducer and that the cellular response to apoptotic induction is closely related to the state including the cell cycle.

Antigen-Antibody Reactions↗
PubMed1996

Assay for tryptophan hydroxylase activity in rat brain by high-performance liquid chromatography with fluorescence detection.

A highly sensitive and selective liquid chromatographic (HPLC) method with post-column fluorescence detection has been developed for the determination of tryptophan 5-monooxygenase activity in rat brain tissue homogenate. 5-Hydroxytryptophan, formed enzymatically from tryptophan (incubation time, 20 min), is extracted with perchloric acid and determined by HPLC. Detection is performed fluorometrically after post-column derivatization by a reaction with benzylamine in the presence of potassium hexacyanoferrate (III). The lower limit of detection for 5-hydroxytryptophan formed enzymatically is 100 fmol at a signal-to-noise ratio of three.

5-Hydroxytryptophan↗
PubMed1995

[Clinico-pathological studies on three preoperative combined treatments for rectal cancer].

To prevent postoperative local recurrence of rectal cancer, we treated patients using preoperative hyperthermia (5-6 times), irradiation (total 30 Gy) and 5-fluorouracil suppository (2,000-2,500 mg). The subjects were 31 patients given combined treatments and 28 patients given surgery alone. The results were as follows: 1. Histologically, therapeutic effects were recognized in 80.6% of patients receiving combined treatments. 2. The mean distance from the adventitia to the site of cancer infiltration was 6.54 mm in the combined treatments group and 3.35 mm in the surgery alone group. The difference between the two was significant (p < 0.05). 3. The rate of local recurrence in the combined treatments group was less than that in the surgery alone group. 4. No systemic side effects nor severe complications were observed during hospitalization in the combined treatments group. 5. The survival rate of the combined treatments group was higher than that of the surgery alone group. It was considered that combined preoperative treatments for rectal cancer were beneficial to survival and local control.

Adult↗
PubMed1993

An amber mutation of prion protein in Gerstmann-Sträussler syndrome with mutant PrP plaques.

We found an amber mutation in the open reading frame of the prion protein (PrP) gene. The codon 145 mutation (tyrosine to stop) was recognized on a PrP allele of a patient with Alzheimer-type clinical course. Pathologic examination revealed many amyloid plaques and neurofibrillary changes. However, the amyloid plaques in this patient were not composed of beta/A4 protein, but of PrP. Both wild and mutant PrP alleles were detected in the cerebral mRNA; however, only C-terminal truncated PrP was detected in the kuru plaques. We herein present evidence that only mutant PrP aggregates to make kuru plaques in the central nervous system.

Adult↗
PubMed1993

Persistence of reorganized synaptic connectivity in the amygdala of kindled rats.

Kindling stimulation was applied to the basolateral amygdala of adult rats, and the density of dendritic synapses was examined under the electron microscope in the medial amygdaloid nucleus (MAN) contralateral to the site of stimulation, and an unfolding correction of biasedness was made. When generalized motor seizures had been induced for 5 days consecutively, the kindling was considered to be complete. The number of dendritic synapses, but not the number of somatic synapses, was markedly decreased in the MAN of the kindled rats. Reductions in numbers were marked in the case of both dendritic shaft and spine synapses. The reductions in numbers of shaft and spine synapses were similarly evident in the MAN of kindled rats 100 days after stimulation was discontinued. The numbers of dendritic synapses were similarly decreased in the rats that received additional bouts of stimulation subsequent to the completion of kindling. Thus, once the kindling was completed, the newly acquired synaptic connectivity was preserved in the MAN. These findings indicate that the remodeling of synaptic connectivity was a morphological correlate of the kindling in the MAN.

Amygdala↗
PubMed1993

High-performance liquid chromatographic determination of 5-hydroxyindoles by post-column fluorescence derivatization.

A selective and sensitive high-performance liquid chromatographic method with post-column fluorescence detection has been developed for the determination of 5-hydroxyindoles. Five biogenic 5-hydroxyindoles (5-hydroxytryptophan, 5-hydroxytryptamine, 5-hydroxyindol-3-ylacetic acid, 5-hydroxytryptophol and N-acetyl-5-hydroxytryptamine) were separated by isocratic elution on a reversed-phase column, TSKgel ODS-80Tm, and then converted into fluorescent derivatives by post-column reaction with benzylamine and potassium hexacyanoferrate(III) reagents. The detection limits (signal-to-noise ratio = 3) for the indoles were in the range 140-470 fmol per injection volume (100 microliters). The method was applied to the determination of 5-hydroxyindol-3-ylacetic acid in human urine, with direct sample injection.

Adult↗
PubMed1993

Influence of immunotherapy on antisperm antibody titer in unexplained recurrent aborters.

PROBLEM: The mechanism of the beneficial effect of immunotherapy for human reproductive wastage remains to be elucidated. Because some women with unexplained recurrent spontaneous abortion are immunized with their partner's lymphocytes, it is important to determine whether such immunization results in elevation or enhancement of immunity to spermatozoa, because antigenic cross-reactivity between lymphocytes and spermatozoa has been reported. METHOD: The present study was initiated to evaluate the changes in antisperm antibody titer and lymphocyte subsets after immunotherapy as compared to before immunotherapy. Antisperm antibody detection was performed by SpermCheck Assay, which is based on a modification of the immunobead test. Maternal lymphocyte subsets were analyzed in two-color flow-cytometric experiments. RESULTS: The percentage of antibody-positive sperm decreased significantly (P = 0.0008) after immunotherapy. The percentage of B(CD19+) cells (P = 0.0003), cytotoxic T(CD8+ and CD11b-) cells (P = 0.02) and the Th/Ts ratio (P = 0.005) decreased significantly, while suppressor T(CD8+ and CD11b+) cells increased significantly (P = 0.0002) after the immunotherapy. This suggests that cell-mediated immunosuppression was induced by immunotherapy. CONCLUSION: The data of the present study suggest that antisperm antibodies have potential for use as a marker for a deficiency in maternal genital tract immunosuppressor mechanisms and that immunotherapy could be an effective treatment for women with antisperm antibodies who have unexplained recurrent abortions.

Abortion, Habitual↗
PubMed1993

A uterine muscle contractile substance obtained from a human placental cDNA library.

A cDNA clone coding for an oxytocin-like substance was prepared from a human placental cDNA library using oxytocin antiserum. The cDNA size was approximately 900 bp. A mammalian expression vector containing the cDNA was constructed and transfected into Chinese hamster ovary (CHO) cells. The expression of immunoreactivity to oxytocin antiserum was observed by radioimmunoassay. The cultured medium of the transfected cells was assayed for uterine muscle contractile bioactivity using a Magnus apparatus. Bioactivity was eliminated by incubation with oxytocin antiserum. Thus, the cDNA clone, screened with oxytocin antibody, is surmised to code for an oxytocin-like activity, but the nucleotide and amino acid sequences responsible for the biological activity remain to be clarified.

Animals↗
PubMed1992

Survey of 1120 Japanese women with a history of recurrent spontaneous abortions.

Our recent 7-year clinical survey showed that among the 1120 women with repeated spontaneous abortions registered in this clinic, 2898 out of a total of 3216 pregnancies (90.1%) had terminated in spontaneous abortion. Among these wastages, 84.2% occurred before 12 weeks of gestation, and 11.1 percent occurred between 12 and 15 weeks. Through routine examination of reproductive wastage, 82 (9.9%) of the 825 Japanese couples examined were shown to have either a chromosomal abnormality or normal variants in the wife and/or husband, thus demonstrating no racial difference in the incidence of chromosomal abnormalities in infertile patients in comparison with studies performed in other countries. One hundred and forty-seven congenital uterine anomalies (14.7%) were found in 1000 hysterosalpingographies, and 12 of 148 examined females were positive for anti-cardiolipin antibody. 393 other females with no major abnormalities likely to induce spontaneous abortions were indicated for immunotherapy. Ample time spent on genetic counseling prevented further reproductive wastage, and ideal metroplasty resulted in a successful post-operative pregnancy course in more than 85% of cases. Immunosuppressant and anticoagulant therapy decreased the serum titer of anti-cardiolipin antibody, enabling pregnancies to be maintained to term. Immunotherapy utilizing the husband's lymphocytes also brought more than 80% of pregnancies to successful completion, with 200 deliveries achieved with this therapy. In contrast, 64.1% of pregnancies again terminated spontaneously in patients who were indicated for immunotherapy but did not receive treatment. The findings of the present study suggest that the causes of reproductive wastage, especially the etiology of early recurrent spontaneous abortion, are complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Habitual↗
PubMed1992

Quick measurement of serum unconjugated estrogens, and its clinical application to abnormal pregnancies and ovarian follicle maturation.

Using an automated HPLC system reported recently by us (J Clin Lab Anal 4:410-413, 1990), serum unconjugated estriol and estradiol (u-E3 and u-E2) can be measured within 22 min. The clinical value of this method was evaluated in this study with abnormal pregnancies, twin pregnancies, and pregnancies associated with fetal anencephaly or complicated by gestational toxicosis or diabetes mellitus. A significant correlation was demonstrated between an abrupt decrease in serum u-E3 level and an abnormal pattern on fetal heart rate monitor. Since urinary E3 was not sensitive enough to detect any depressed fetal condition, serum u-E3 is better biochemical parameter for assessment of fetal well-being. In addition, u-E2 was measured in the sera of nonpregnant women with separation chromatography as a pretreatment in order to obtain higher sensitivity of the system. This modified HPLC system enabled us to determine the serum u-E2 in about 60 min with the minimal detectable value of 80 pg/ml; the coefficient of correlation with RIA was 0.822. As a result, this quick measurement of u-E3 and u-E2 by our HPLC system revealed to be useful not only for evaluating fetoplacental function but also for monitoring ovarian follicle maturation.

Anencephaly↗
PubMed1992

Neurotransmitter changes in early- and late-onset Alzheimer-type dementia.

Neurotransmitter-related markers were examined in Alzheimer-type dementia (ATD) and studied whether or not there is biochemical difference between the early- and late-onset sub-groups. Postmortem brains were obtained from neuropathologically diagnosed ATD patients and control subjects with no clinico-neuropathological findings indicative of neuropsychiatric diseases. Neurochemical data in the early- and late-onset groups were compared to the age-matched younger and older control groups, respectively, and expressed as a percentage of the mean value in the respective controls. Choline acetyltransferase activity and concentrations of serotonin and noradrenaline were more severely depleted in the early-onset ATD group than in the late-onset ATD group. These findings indicative of heterogeneity of ATD patients were discussed from the pathogenetic and therapeutic viewpoints.

Aged↗
PubMed1992

[Loss of catecholaminergic neuron in the hypothalamus of multiple system atrophy].

Autonomic failure is one of the primary clinical features of multiple system atrophy (MSA); while the hypothalamus is thought to be a higher center regulating the autonomic nervous system. In the hypothalamus, catecholamine depletion had been confirmed by neurochemical studies but no marked changes had yet been demonstrated by pathological studies. Using three MSA and three control cases, we evaluated the quantitative changes of catecholamine (CA)-containing neurons in the hypothalamus. As markers of CA neurons, neuromelanin (NM)- and tyrosin hydroxylase (TH)-containing neurons were stained by Fontana-Masson and the immunohistochemical technique alternatively. Serial coronal sections, 10 microns thick, were evaluated every tenth section for NM neurons, while two sections were evaluated for TH neurons. The distributions of NM and TH neurons were almost identical; most of them were clustered in the periventricular and arcuate nuclei. The mean numbers of NM and TH neurons per slice were significantly lower in MSAs than in the controls (T test, p less than 0.01); the former were 21.0, 31.6, and 13.7 in MSAs and 78.4, 54.1, and 84.3 in the controls, while the latter were 1.5, 15.5, and 20.5 in MSAs and 48.0, 62.0, and 50.5 in the controls. The clinico-pathological correlation was suggested by the significant differences in the number of TH neurons between two MSA cases: a case with severe orthostatic hypotension and a case with a milder one. The ratio of TH and NM neurons, as obtained from the adjusted sections, was constant in all MSA cases, and there was a positive statistical correlation, but it altered in each control case.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗