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Biomedical subjects

K Saeki

Publications and source records attributed to K Saeki.

At least 127 records · Page 7Linked to original sources
PubMed1998

Prediction of efficacy of interferon treatment of chronic hepatitis C by multivariate analysis and a new classification.

One hundred and fifteen patients with chronic hepatitis C were administered interferon (IFN) and classed into two groups: (i) complete responders (CR), HCV-RNA continuously negative 1 year after treatment; and (ii) non-responders (NR), positive 1 year after treatment. Multivariate analysis comprised eight variables: age, sex, transfusion history, alanine aminotransferase level, viral genotype, level of viremia, type of IFN, and total amount of IFN. The HCV-RNA level was correlated with complete response (P = 0.0175). Liver biopsy specimens were classified into four grades and stages according to the measure of severity and the extent of fibrosis, respectively. There was no correlation between the efficacy rate and grading. However, in staging there was a difference in the efficacy of IFN between stages 1 or 2, and stage 3 (0.05 < P < 0.1 and 0.01 < P < 0.025, respectively). Of the CR patients, 0% (0/5) were at stage 0 (no fibrosis); 27.5% (22/80) at stage 1 (mild); 42.9% (6/14) at stage 2 (moderate); and 6.3% (1/16) at stage 3 (severe fibrosis). Thus the new classification would be useful in predicting roughly the efficacy of IFN.

Adolescent↗
PubMed1998

Enzymatic properties of a novel liquefying alpha-amylase from an alkaliphilic Bacillus isolate and entire nucleotide and amino acid sequences.

A novel liquefying alpha-amylase (LAMY) was found in cultures of an alkaliphilic Bacillus isolate, KSM-1378. The specific activity of purified LAMY was approximately 5,000 U mg of protein-1, a value two- to fivefold greater between pH 5 and 10 than that of an industrial, thermostable Bacillus licheniformis enzyme. The enzyme had a pH optimum of 8.0 to 8.5 and displayed maximum activity at 55 degreesC. The molecular mass deduced from sodium dodecyl sulfate-polyacrylamide gel electrophoresis was approximately 53 kDa, and the apparent isoelectric point was around pH 9. This enzyme efficiently hydrolyzed various carbohydrates to yield maltotriose, maltopentaose, maltohexaose, and maltose as major end products after completion of the reaction. Maltooligosaccharides in the maltose-to-maltopentaose range were unhydrolyzable by the enzyme. The structural gene for LAMY contained a single open reading frame 1, 548 bp in length, corresponding to 516 amino acids that included a signal peptide of 31 amino acids. The calculated molecular mass of the extracellular mature enzyme was 55,391 Da. LAMY exhibited relatively low amino acid identity to other liquefying amylases, such as the enzymes from B. licheniformis (68.9%), Bacillus amyloliquefaciens (66.7%), and Bacillus stearothermophilus (68.6%). The four conserved regions, designated I, II, III, and IV, and the putative catalytic triad were found in the deduced amino acid sequence of LAMY. Essentially, the sequence of LAMY was consistent with the tertiary structures of reported amylolytic enzymes, which are composed of domains A, B, and C and which include the well-known (alpha/beta)8 barrel motif in domain A.

Amino Acid Sequence↗
PubMed1998

Timing of completion of the first meiotic division in bovine oocytes after maintenance of meiotic arrest with cycloheximide and their subsequent development.

This study examined the timing of completion of meiosis I of bovine oocytes in which meiotic resumption had been inhibited by cycloheximide (CHX), and also determined the optimum interval of maturation in culture for subsequent fertilization and development. Most oocytes treated with CHX reached metaphase II at 16 hr in the maturation culture, while control oocytes did at 20 hr. CHX-treated oocytes cultured for 16 hr were normally fertilized but failed to develop into blastocysts. Maturation in culture for 20 hr resulted in comparable development for control oocytes. The results indicate that nuclear maturation of CHX-treated oocytes was completed 4 hr faster than for control oocytes, however the same interval of maturation as that of control oocytes is necessary for subsequent development to blastocysts.

Animals↗
PubMed1998

[Present situation of leprosy in highly endemic area of tropical Asia--a seroepidemiological study of Mycobacterium leprae infection in general inhabitants].

One of the most important unsolved problems in epidemiology of leprosy is the heterogeneous geographic distribution of the disease. There are highly endemic area called "Pocket" in the endemic countries. Little is known why leprosy is so endemic in the area. We conducted, therefore, an epidemiological study on M. leprae infection and distribution of leprosy bacilli in the environment by using serological and molecular biological techniques. It was found that considerable number of general inhabitants in the pocket are infected with leprosy bacilli and more than 20% of the villagers are carrying M. leprae on the surface of the nasal cavity; suggesting that leprosy bacilli in the residential environment play an important role in high prevalence of leprosy in the endemic area. New preventive measures such as chemoprophylaxis, in addition to MDT, will be needed for global elimination of the disease.

Adolescent↗
PubMed1998

[Apoptosis of B lymphocytic leukemia induced by anticancer drugs and their cell cycle specificity].

OBJECTIVE: Evaluating the effect of apoptosis induced by anticancer drugs on human B lymphocytic leukemia cell lines (Nalm-6) and their cell cycle specificity. METHODS: Nalm-6 cells were treated with various anticancer drugs for 8-24 hours. Apoptotic cells and their cell cycle specificity were measured by using hypodiploid DNA-FCM and TdT assay + DNA staining. RESULTS: ADR, VP16, CPT, MTX, Ara-C could markedly induce apoptosis of Nalm-6 cells in S phase. CPM, PRD, 6MP were less capable of inducing apoptosis. CPM in high dose resulted in cell necrosis. PRD induced apoptosis in G1 phase, while 6MP induced apoptosis in G1 and S phase. The effect of CPM showed no marked cell cycle specificity. CONCLUSION: Hypodiploid DNA-FCM and TdT assay + DNA staining can be used to detect both tumor cell apoptosis and their cell cycle specificity which is helpful to predict prognosis and to design new chemotherapy regimen.

Antineoplastic Agents↗
PubMed1997

Cell density-dependent apoptosis in HL-60 cells, which is mediated by an unknown soluble factor, is inhibited by transforming growth factor beta1 and overexpression of Bcl-2.

We report a novel mode of apoptosis induction observed in human leukemic HL-60 cells. These cells spontaneously underwent apoptosis in the course of proliferation when the cell density became higher than 1 x 10(6)/ml. This occurred under ordinary in vitro culture conditions, with or without fetal calf serum. Even the low density cells were committed to undergo apoptosis if they were cultured under artificially concentrated conditions. Replacement of the culture supernatant of the low density cells by that of the high density ones resulted in apoptosis induction in the former cells. This apoptosis-inducing activity of the high density cell culture supernatant was completely eliminated by the action of trypsin but was fully restored following ultrafiltration by 3-kDa pore-sized membrane. A strong apoptosis-inducing activity was recovered from the culture supernatant of the high density HL-60 cells at a specific fraction in reverse-phase column chromatography. Neither an interleukin-beta converting enzyme inhibitor nor CPP-32 inhibitor blocked the induction of cell density-dependent apoptosis in HL-60 cells, although overexpression of Bcl-2 protein markedly attenuated the induction of this mode. Surprisingly, transforming growth factor-beta1 and activin A did not induce but, rather, inhibited the induction of cell density-dependent apoptosis. These data suggest that HL-60 cells release an unknown low molecular weight peptide-containing factor in response to an increase in cell density to induce apoptosis in an autocrine manner and that the interleukin-beta converting enzyme-independent intracellular machinery for this mode of apoptosis is strongly affected by signaling events through the transforming growth factor-beta1 receptor and by the action of Bcl-2 oncoprotein.

Activins↗
PubMed1997

Immunohistochemical localization of macrophage migration inhibitory factor (MIF) in tanycytes, subcommissural organ and choroid plexus in the rat brain.

We investigated the immunohistochemical localization of the macrophage migration inhibitory factor (MIF) in the rat brain. In addition to epithelial ependymal cells lining the ventricular wall, tanycytes in the basomedial hypothalamus were heavily immunostained. The immunoreactive processes of tanycytes made contacts to sinusoidal capillaries and reached the pial surface forming an immuno-positive structure at the floor of the hypothalamus. Other immunoreactive cells contained the subcommissural organ in the roof of the third ventricle and the epithelial lamina of the choroid plexus. The localization of MIF in cells which have contact with cerebrospinal fluid and blood vessels suggests that MIF might play a role as a humoral factor in the brain.

Animals↗
PubMed1997

Membrane localization, topology, and mutual stabilization of the rnfABC gene products in Rhodobacter capsulatus and implications for a new family of energy-coupling NADH oxidoreductases.

The rnf genes in Rhodobacter capsulatus are unique nitrogen fixation genes that encode potential membrane proteins (RnfA, RnfD, and RnfE) and potential iron-sulfur proteins (RnfB and RnfC). In this study, we first analyzed the localization and topology of the RnfA, RnfB, and RnfC proteins. By activity and immunoblot analysis of expression of translational fusions to Escherichia coli alkaline phosphatase, RnfA protein was shown to span the chromatophore membrane with its odd-numbered hydrophilic regions exposed to periplasm. By alkaline treatment of membrane fractions and following immunoblot analysis using antibodies against recombinant proteins expressed in E. coli, both RnfB and RnfC proteins were revealed to situate at the periphery of the chromatophore membranes. Second, mutual interaction of the Rnf proteins was analyzed by immunochemical determinations of RnfB and RnfC proteins in rnf mutants and their complemented derivatives. The contents in cellular fractions indicated that RnfB and RnfC stabilize each other and that the presence of RnfA is necessary for stable existence of both proteins. These results support a hypothesis that the Rnf products are subunits of a membrane complex. Finally, we detected homologs of rnf genes in Haemophilus influenzae and Vibrio alginolyticus by data base searches and in E. coli by cloning of a fragment of an rnfA homolog followed by a data base search. Close comparisons revealed that RnfC has potential binding sites for NADH and FMN which are similar to those found in proton-translocating NADH:quinone oxidoreductases and that RnfA, RnfD, and RnfE show similarity to subunits of sodium-translocating NADH:quinone oxidoreductases. We predict that the putative Rnf complex represents a novel family of energy-coupling NADH oxidoreductases.

Amino Acid Sequence↗
PubMed1997

Developmental capacity of bovine oocytes following inhibition of meiotic resumption by cycloheximide or 6-dimethylaminopurine.

This study was conducted to assess the fertilizability and developmental capacity of bovine oocytes which had been maintained in meiotic arrest by either a protein synthesis inhibitor, cycloheximide (CHX), or an inhibitor of serine/threonine protein kinases, 6-dimethylaminopurine (6-DMAP). Both CHX and 6-DMAP reversibly prevented nuclear maturation of nearly all oocytes for 24 h. After the reversal of arrest, CHX-treated oocytes could be successfully matured and fertilized. They developed to the blastocyst stage at slightly lower rates than oocytes cultured without inhibition for 22 h prior to sperm addition but at higher rates than those incubated in a medium containing no inhibitors for 46 h prior to fertilization. Oocytes inhibited by CHX for 48 h matured and fertilized normally but failed to develop into blastocysts. Even though 6-DMAP-treated oocytes completed meiosis I after removal from the drug, the rates of fertilization and blastocyst formation were lower than for untreated oocytes or CHX-treated oocytes. Effects of adding FSH and/or estradiol-17 beta (E(2)) during CHX-inhibition for 24 h were also examined. Embryos from oocytes treated with CHX and E(2) or with CHX and FSH + E(2) developed into blastocysts at similar rates as the controls. Further development of inhibited oocytes was examined by transferring blastocysts derived from oocytes inhibited by CHX with FSH and E(2) for 24 h to recipient heifers. Two calves were obtained following transfer. These results indicate that CHX-inhibited oocytes retain developmental competence, while 6-DMAP-inhibited oocytes after the reversal of arrest have reduced capacities for fertilization and further development. The addition of FSH and E(2) during CHX-inhibition improves development to the blastocyst stage of the oocytes that are capable of initiating and maintaining pregnancy after embryo transfer to recipient animals.

Journal Article↗
PubMed1997

Identification of bradykinin, substance P, and neurokinin A in human dental pulp.

Methodology was developed that uses reverse phase, high performance liquid chromatography (HPLC) to identify and quantify bradykinin, substance P, and neurokinin A contained in dental pulp tissue. Pulp tissue was prepared and homogenized from teeth frozen in liquid nitrogen, Known amounts of three substances found in inflamed tissue were added to the homogenized tissue and also to bovine serum albumin (BSA) (positive control), and supernatants were analyzed using HPLC. Other pulp tissue was prepared and analyzed without the addition of the substances. Recovery from the pulp and BSA with added substances was similar, with bradykinin recovered maximally. In pulp tissue without additions, all three substances were recovered. Thus HPLC appears to be a viable alternative to other methods for identification of these substances and allows for their quantification.

Animals↗
PubMed1997

Differential induction of apoptosis on human lymphoblastic leukemia Nalm-6 and Molt-4 cells by various antitumor drugs.

To investigate how chemotherapy agents interact with the leukemic cell death pathway, we examined apoptosis of human lymphoblastic leukemia cells (Nalm-6 and Molt-4) treated with various anticancer drugs (etoposide (VP-16), camptothecin (CPT), adriamycin (ADR), cytosine arabinoside (Ara-C), methotrexate (MTX), 6 mercaptopurine (6MP), cyclophosphamide (CPM), vincristine (VCR) and prednisolone (PRD)) by flow cytometric procedures. The proportion of apoptotic cells was estimated from the presence of cells with a fractional DNA content in the DNA histograms after the incubation of drug-treated cells with a DNA extraction buffer. Treatment with Ara-C, CPT, VP-16 and ADR resulted in rapid apoptosis with 40-60% apoptotic cells by 8 h. Treatment with MTX, VCR, 6MP and PRD induced no apparent apoptosis until 12 h, but further treatments with these drugs resulted in apoptosis with 50% (MTX), 20-30% (6MP and VCR) and 5-10% (PRD) apoptotic cells, respectively, at 24 h. CPM induced apoptosis with 10-20% apoptotic cells at 10(-6) M, but higher doses (> 10(-5) M) caused a rapid cell death by necrosis. The cell cycle position of apoptotic cells was assessed by the terminal deoxynucleotidyl transferase (TdT) assay of DNA strand breaks combined with DNA staining. MTX, Ara-C, CPT, VP-16 and ADR preferentially induced apoptosis in the S phase. PRD and 6MP induced apoptosis in the G1 phase and G1 + S phases, respectively. CPM showed no cell cycle phase specificity. These findings suggested that the susceptibility of cells to apoptosis was not the sole determinant of cellular sensitivity of cytotoxic drugs.

Antineoplastic Agents↗
PubMed1997

Identification of spike protein residues of murine coronavirus responsible for receptor-binding activity by use of soluble receptor-resistant mutants.

We previously demonstrated by site-directed mutagenesis analysis that the amino acid residues at positions 62 and 214 to 216 in the N-terminal region of mouse hepatitis virus (MHV) spike (S) protein are important for receptor-binding activity (H. Suzuki and F. Taguchi, J. Virol. 70:2632-2636, 1996). To further identify the residues responsible for the activity, we isolated the mutant viruses that were not neutralized with the soluble form of MHV receptor proteins, since such mutants were expected to have mutations in amino acids responsible for receptor-binding activity. Five soluble-receptor-resistant (srr) mutants isolated had mutations in a single amino acid at three different positions: one was at position 65 (Leu to His) (srr11) in the S1 subunit and three were at position 1114 (Leu to Phe) (srr3, srr4, and srr7) and one was at position 1163 (Cys to Phe) (srr18) in the S2 subunit. The receptor-binding activity examined by a virus overlay protein blot assay and by a coimmunoprecipitation assay showed that srr11 S protein had extremely reduced binding activity, while the srr7 and srr18 proteins had binding activity similar to that of wild-type cl-2 protein. However, when cell surface receptors were used for the binding assay, all srr mutants showed activity similar to that of the wild type or only slightly reduced activity. These results, together with our previous observations, suggest that amino acids located at positions 62 to 65 of S1, a region conserved among the MHV strains examined, are important for receptor-binding activity. We also discuss the mechanism by which srr mutants with a mutation in S2 showed high resistance to neutralization by a soluble receptor, despite their sufficient level of binding to soluble receptors.

Animals↗
PubMed1997

Modification of the carcinogenic potency of quinoline, a hepatocarcinogen, by fluorine atom substitution: evaluation of carcinogenicity by a medium-term assay.

The potent mutagen, 5-fluoroquinoline (5-FQ), and non-mutagenic 3-fluoroquinoline (3-FQ) were tested for hepatocarcinogenicity using a medium-term assay system employing quinoline, a moderately mutagenic hepatocarcinogen, as a reference. F344 male rats were given a single i.p. injection of a submanifestational dose of diethylnitrosamine (DEN, 200 mg/kg). Then, quinoline, 3-FQ, or 5-FQ at two doses (0.1%, and 0.05%) was added to their diet for a period of 6 weeks, starting from 2 weeks after the DEN injection. Control groups were administered DEN alone. All rats were subjected to a partial (two-thirds) hepatectomy at the end of week 3 and sacrificed at the end of week 8. The number and areas of GST-P (placental glutathione S-transferase)-positive foci induced in the liver increased significantly as a result of treatment with 0.1% quinoline, and this increase was dramatic with 5-FQ at both doses, whereas no increases were noted with 3-FQ at either dose. Thus, the results of the medium-term carcinogenicity assay predicted that quinoline, a hepatocarcinogen, would be deprived of carcinogenicity by fluorine atom substitution at position 3, and would conversely be endowed with a higher carcinogenic capacity by substitution at position 5. A semi-quantitative relationship was demonstrated between carcinogenic and mutagenic potencies.

Animals↗
PubMed1997

Dual stimulatory and inhibitory effects of fluorine-substitution on mutagenicity: an extension of the enamine epoxide theory for activation of the quinoline nucleus.

Nineteen mono- and di-fluorinated derivatives of quinoline, 1,7-phenanthroline, 1,10-phenanthroline, benzo[h]quinoline, and benzo[f]quinoline were subjected to analysis of their structure-mutagenicity relationships. For this purpose, six new fluorinated derivatives were synthesized. The results support that the enamine epoxide structure of the pyridine moiety, as well as the bay-region epoxide structure, is responsible for mutagenicity. Formation of K-region epoxides might involve a detoxification process rather than mutagenic activation.

Benzo(a)pyrene↗
PubMed1997

The seroprevalence of HTLV-I in patients with ocular diseases, pregnant women and healthy volunteers in the Kanto district, central Japan.

HTLV-I has been shown to be related to the development of inflammatory diseases in various organs such as the eyes, lungs and joints. In south-west Japan where HTLV-I is highly endemic, the term 'HTLV-I associated complex' has been approved. To investigate the seroprevalence of HTLV-I in the Kanto district in central Japan, we have estimated the frequency of seropositivity to HTLV-I in 2,110 patients with various ocular diseases and 2,683 pregnant women, in addition to 5,336 healthy volunteers. Of the healthy volunteers, only 42 (0.79%) were seropositive, and the HTLV-I seroprevalence in pregnant women was also only 16/2,683 (0.60%) which was almost equal to that in female healthy volunteers aged 15-44 years (0.59%). In patients with various ocular diseases, however, there was significantly higher seroprevalence of HTLV-I (2.32%) compared with healthy volunteers in each sex (male: p = 0.0029; female: p = 0.000023). These results suggest that the seroprevalence of HTLV-I in the Kanto district is much lower than in south-west Japan. On the other hand, HTLV-I infection was shown to be correlated to ocular diseases also in the Kanto district. In particular, we found a higher seroprevalence of HTLV-I in patients with inflammatory ocular disease, such as endogenous uveitis, episcleritis, retinitis pigmentosa and degenerative choroiditis. This possibly suggests a causative role of HTLV-I in the development of these inflammatory ocular diseases also where HTLV-I is not endemic.

Adolescent↗
PubMed1997

Subglottic stenosis in Wegener's granulomatosis limited to the head and neck region.

Subglottic stenosis as a complication of Wegener's granulomatosis (WG) is a relatively rare lesion and is difficult to treat surgically once stenosis becomes sufficiently severe to cause inspiratory dyspnea. Thus, it is important to diagnose WG in its early stages to prevent troublesome subglottic stenosis from developing by initiating immunosuppressive therapy. The authors report on a 30-year-old woman suffering from subglottic stenosis of sudden onset due to protracted WG limited to the head and neck region. She had had exudative otitis media for 13 years and saddle nose and nasal crusting for five years. Repeated biopsies of the nasal mucosa and enzyme-linked immunosorbent assays for cytoplasmic patterns of antineutrophil cytoplasmic autoantibody (cANCA) had failed to establish the diagnosis. However, further histologic examination of the nasal mucosa showed vasculitis, and indirect immunofluorescence detected the presence of cANCA. Thus, the diagnosis of WG was confirmed 13 years after the appearance of the initial symptoms in the ear. The patient was given prednisolone (60 mg/day for five days), which greatly relieved the subglottic stenosis. The prednisolone dosage was then tapered to 5 mg/day.

Adolescent↗
PubMed1997

Serologic survey for HTLV-I in Kanagawa Prefecture.

To investigate the seroprevalence of HTLV-I in Kanagawa Prefecture (central Japan), we tested the sera of 8,264 healthy volunteers and 2,414 pregnant women. Of the 8,264 healthy volunteers, 66 (0.80%) were seropositive. The seroprevalence of HTLV-I in the pregnant women was 14/2,414 (0.58%), and this rate was almost identical to that in the healthy female volunteers 15 to 44 years of age (0.59%). These figures indicate that the seroprevalence of HTLV-I in Kanagawa Prefecture is very low and that sexual contact may not be an important contributory factor.

Adolescent↗