Biomedical subjects

Y Nakano

Publications and source records attributed to Y Nakano.

At least 55 records · Page 3Linked to original sources

PubMed2001

Cobalamin deficiency results in severe metabolic disorder of serine and threonine in rats.

Dietary cobalamin (vitamin B12; Cbl) deficiency caused significant increases in plasma serine, threonine, glycine, alanine, tyrosine, lysine and histidine levels in rats. In particular, the serine and threonine levels were over five and eight times, respectively, higher in the Cbl-deficient rats than those in the sufficient controls. In addition, some amino acids, including serine and threonine, were excreted into urine at significantly higher levels in the deficient rats. When Cbl was supplemented into the deficient rats for 2 weeks, in coincidence with the disappearance of the urinary excretion of methylmalonic acid (an index of Cbl deficiency), the plasma serine and threonine levels were normalized. These results indicate that Cbl deficiency results in metabolic disorder of certain amino acids, including serine and threonine. The expression level of hepatic serine dehydratase (SDH), which catalyzes the conversion of serine and threonine to pyruvate and 2-oxobutyrate, respectively, was significantly lowered by Cbl deficiency, even though Cbl does not participate directly in the enzyme reaction. The SDH activity in the deficient rats was less than 20% of that in the sufficient controls, and was normalized 2 weeks after the Cbl supplementation. It is thus suggested that the decrease of the SDH expression relates closely with the abnormalities in the plasma and urinary levels of serine and threonine in the Cbl-deficient rats.

Animals↗

PubMed2001

Lysophosphatidic acid enhances airway response to acetylcholine in guinea pigs.

Inhalation of lysophosphatidic acid (LPA, 1-100 microg/ml) for 2 min enhanced the airway response induced by intravenous injection of ACh in guinea pigs. At 30 min after inhalation of LPA, the airway response to ACh was two fold higher than that before inhalation. This enhancement of airway response to ACh was partially inhibited by capsaicin desensitization or bilateral vagotomy. These results suggested that the enhancement of airway response to ACh induced by LPA may be due to the activation of capsaicin-sensitive fibers. It can be also contribute to bronchial asthma or other types of pulmonary disease such as cough variant asthma and atopic cough.

Acetylcholine↗

PubMed2001

Identification of selective inhibitors of cyclin dependent kinase 4.

A new structural type of kinase inhibitor, containing a benzocarbazole nucleus, has been identified. Members of the series are selective for inhibition of the cyclin dependent kinase family of enzymes. Although the cdks are highly homologous, representatives of the series showed intra-cdk selectivities, especially for cdk4. SAR studies elucidated the important features of the molecules for inhibition.

Carbazoles↗

PubMed2001

NADPH-dependent glutathione peroxidase-like proteins (Gpx-1, Gpx-2) reduce unsaturated fatty acid hydroperoxides in Synechocystis PCC 6803.

Here we isolated and characterized two genes (slr1171, slr1992) designated gpx-1 and gpx-2, respectively, encoding glutathione peroxidase (GPX)-like proteins (Gpx-1, Gpx-2) from Synechocystis PCC 6803. The deduced amino acid sequences for gpx-1 and gpx-2 showed high similarity to those of GPX-like proteins from higher plants and mammalian GPXs, respectively. Surprisingly, both recombinant proteins in Escherichia coli were able to utilize NADPH, but not reduced glutathione, as an electron donor and unsaturated fatty acid hydroperoxides or alkyl hydroperoxides as an acceptor. It seems accurate to refer to Gpx-1 and Gpx-2 as NADPH-dependent GPX-like proteins that serve as a new defense system for the reduction of unsaturated fatty acid hydroperoxides.

Amino Acid Sequence↗

PubMed2001

Non-dipper phenomenon in essential hypertension is related to blunted nocturnal rise and fall of sympatho-vagal nervous activity and progress in retinopathy.

Although the relation between the blunted nocturnal decline in blood pressure and target organ damages is well established, the mechanism underlying these results has not been clarified. We investigated the relationship among heart rate variability, nocturnal change in blood pressure and the severity of cardiac and extracardiac target organ damages caused by essential hypertension. We studied 52 Japanese inpatients with essential hypertension (24 men and 28 women; mean age, 49+/-3 years). After a stabilization period of 1 week, ambulatory blood pressure monitoring (ABPM) and 24-h ECG monitoring were performed and analyzed. The non-dipper subjects were defined as those whose nocturnal decrease of mean BP was < 10% of daytime blood pressure (BP). The sex, age, body mass index. duration of hypertension, and 24-h BP were similar in dipper (n = 34) and non-dipper (n = 18) patients. The left ventricular mass index (LVMI) was significantly higher and the degree of hypertensive retinopathy was significantly worse in the non-dipper patients than that of the dipper patients. In the non-dipper patients, indexes of time-domain analysis such as the sum of differences between adjacent RR intervals (NNDrms), the number of pairs of adjacent RR intervals differing by more than 50 ms in the entire recording (RR 50) were significantly lower than that of the dipper patients. Additionally, as for spectral analysis, daytime low frequency/high frequency (LF/HF) was higher and nighttime high frequency (HF) was lower than that of the dipper patients. Independent predictors were the 24-h mean blood pressure (MBP) for left ventricular hypertrophy (LVH), nighttime systric BP (SBP) for progress in retinopathy and duration of hypertension for proteinuria. In conclusion, decrease in parasympathetic nervous function and increase in sympathetic nervous function may contribute to occurrence of non-dipper phenomenon, as well as progress in retinopathy.

Blood Pressure↗

PubMed2001

Splenic cathepsin L is maturated from the proform by interferon-gamma after immunization with exogenous antigens.

The processing of foreign protein antigens into peptides requires the participation of various endo/lysosomal proteases in antigen-presenting cells (APCs). In this study, a proenzyme of cathepsin L, procathepsin L, was found to be present in the spleens of naive mice, as demonstrated by immunoblotting. Interestingly, the maturation of cathepsin L from procathepsin L was strongly induced when the host BALB/c mice were immunized with ovalbumin or soluble leishmanial antigen, despite the fact that mouse albumin, a kind of self-antigen, did not have such a potential. Furthermore, foreign antigens, but not self-antigens, could increase the activity of cathepsin L, probably being mediated by interferon-gamma, as demonstrated by in vivo and in vitro experiments. As cathepsin L matured, the efficiency of antigen processing was increased in APCs. These results suggest that endo/lysosomal cathepsin L plays an important role in the immune regulation via antigen processing even in peripheral lymphoid tissues as well as in the thymus.

Animals↗

PubMed2001

Characterization of monoclonal antibodies against ascorbate peroxidase isoenzymes: purification and epitope-mapping using immunoaffinity column chromatography.

We have developed three monoclonal antibodies against spinach chloroplastic (chl-mAb3 and chl-mAb6) and cytosolic (cyt-mAb1) ascorbate peroxidase (APX) isoenzymes to analyze the cross-reactivity and the structure of the epitopes for each monoclonal antibody. All three antibodies reacted specifically with their respective isoenzymes, but none cross-reacted with the others. Immunoreactive fragments in proteolytic recombinant APX isoenzymes were detected by means of the absorption on the corresponding immunoaffinity column. The cyt-mAb1 reacted with a peptide fragment containing the distal His region obtained by the lysyl endopeptidase digestion. The chl-mAb6 was capable of binding to the fragment, D-I-K-E-K-R, which is consistent with an inherent region of chloroplastic isoenzymes. No fragments reacting to the chl-mAb3 could be found in this study, suggesting that the chl-mAb3 recognizes a conformationally constituted epitope of the chloroplastic APX molecule, which may be destroyed by the enzymatic cleavage. We concluded that the peptides identified as epitopes are characteristic evidence of monoclonal antibodies.

Amino Acid Sequence↗

PubMed2001

Mutations in the sterol-sensing domain of Patched suggest a role for vesicular trafficking in Smoothened regulation.

The tumor suppressor gene patched (ptc) encodes an approximately 140 kDa polytopic transmembrane protein [1-3] [corrected] that binds members of the Hedgehog (Hh) family of signaling proteins [4-6] [corrected] and regulates the activity of Smoothened (Smo), a G protein-coupled receptor-like protein essential for Hh signal transduction [7-9] [corrected]. Ptc contains a sterol-sensing domain (SSD) [10, 11] [corrected], a motif found in proteins implicated in the intracellular trafficking of cholesterol [12] [corrected], and/or other cargoes [13-15] [corrected]. Cholesterol plays a critical role in Hedgehog (Hh) signaling by facilitating the regulated secretion and sequestration of the Hh protein [16] [corrected], to which it is covalently coupled. In addition, cholesterol synthesis inhibitors block the ability of cells to respond to Hh [18, 19] [corrected], and this finding points to an additional requirement for the lipid in regulating downstream components of the Hh signaling pathway. Although the SSD of Ptc has been linked to both the sequestration of, and the cellular response to Hh [16, 20, 21] [corrected], definitive evidence for its function has so far been lacking. Here we describe the identification and characterization of two missense mutations in the SSD of Drosophila Ptc; strikingly, while both mutations abolish Smo repression, neither affects the ability of Ptc to interact with Hh. We speculate that Ptc may control Smo activity by regulating an intracellular trafficking process dependent upon the integrity of the SSD.

Amino Acid Sequence↗

PubMed2001

Activating mutation of D835 within the activation loop of FLT3 in human hematologic malignancies.

Mutations of receptor tyrosine kinases are implicated in the constitutive activation and development of human malignancy. An internal tandem duplication (ITD) of the juxtamembrane (JM) domain-coding sequence of the FLT3 gene (FLT3/ITD) is found in 20% of patients with acute myeloid leukemia (AML) and is strongly associated with leukocytosis and a poor prognosis. On the other hand, mutations of the c-KIT gene, which have been found in mast cell leukemia and AML, are clustered in 2 distinct regions, the JM domain and D816 within the activation loop. This study was designed to analyze the mutation of D835 of FLT3, which corresponds to D816 of c-KIT, in a large series of human hematologic malignancies. Several kinds of missense mutations were found in 30 of the 429 (7.0%) AML cases, 1 of the 29 (3.4%) myelodysplastic syndrome (MDS) cases, and 1 of the 36 (2.8%) acute lymphocytic leukemia patients. The D835Y mutation was most frequently found (22 of the 32 D835 mutations), followed by the D835V (5), and D835H (1), D835E (1), and D835N (1) mutations. Of note is that D835 mutations occurred independently of FLT3/ITD. An analysis in the 201 patients newly diagnosed with AML (excluding M3) revealed that, in contrast to the FLT3/ITD mutation (n = 46), D835 mutations (n = 8) were not significantly related to the leukocytosis, but tended to worsen disease-free survival. All D835-mutant FLT3 were constitutively tyrosine-phosphorylated and transformed 32D cells, suggesting these mutations were constitutively active. These results demonstrate that the FLT3 gene is the target most frequently mutated to become constitutively active in AML.

Acute Disease↗

PubMed2001

Regulation of nuclear import by light-induced activation of caged nuclear localization signal in living cells.

A novel fluorescence probe suitable for the study of nuclear import in living cells has been developed. The lysine-128 residue in SV40 T-antigen nuclear localization signal (NLS) was converted to a caged lysine with the amino acid blocked by a photocleavable protecting group. Following irradiation of ultraviolet (UV) light, the caged NLS conjugate translocated into and accumulated in the nucleus within 20 min similar to uncaged NLS conjugate. Maximum import rate saturated approximately 4.78+/-0.21% per minute when the duration of irradiation was more than 1/15 s (22 mW/cm(2)). Caged NLS conjugate tended to distribute near the surface of the nucleus, and this association became stronger after UV irradiation. The caged conjugate enabled us to regulate the initial state of the reaction, both spatially and temporally.

Active Transport, Cell Nucleus↗

PubMed2001

Modulating effects of mucoregulating drugs on the attachment of Haemophilus influenzae.

Non-typable Haemophilus influenzae (NTHI) is one of the three major pathogens implicated in human respiratory infections. The ability to attach with pharyngeal epithelial cells is an important factor for infection and virulence. In the present study we describe the effects of two mucoregulating drugs, S-carboxymethylcysteine (S-CMC) and ambroxol, on the attachment of NTHI to pharyngeal epithelial cells. There was a significant (P < 0.0001, < 0.001 and <0.01) decrease of attachment (8.8 +/ 2.4, 9.2+/-2.5 and 15.4 +/- 5.7 bactreria/cell) compared with the control (17.5 +/- 2.9, 15.5 +/- 3.1 and 18.8 +/- 6.8 bacteria/cell) after cells were treated wth S-CMC at a dose of 100, 10 and 1 microg/ml. After attachment assay, cells treated with S-CMC (100 microg/ml) showed a significant decrease (P < 0.01) of attached bacteria (3.1 +/- 0.8 bacteria/cell) compared with the control (5.9 +/- 1.8 bacteria/cell). Treatment of cells with ambroxol did not influence bacterial attachment. By scanning electron microscopic observation it was found that NTHI attaches to the surface elevations (microplicae) of human pharyngeal epithelial cells. Atomic force microscopic observation revealed that the surface potential of microplicae decreased significantly in cells treated with S-CMC compared with the untreated control cells. As bacteria with negative surface charge attach to the positively charged domain, i.e. microplicae of human pharyngeal epithelial cells, this study suggests that the decrease of attachment of NTHI with epithelial cells after treatment with S-CMC was possibly due to the decrease of surface charge. This study suggests that S-CMC decreases the episodes of respiratory infections in patients with respiratory diseases both by inhibiting the attachment of bacteria to the upper respiratory tract, and by detaching the adherent one.

Adult↗

PubMed2001

Invasive forms of Toxoplasma gondii, Leishmania amazonensis and Trypanosoma cruzi have a positive charge at their contact site with host cells.

We examined the surface charges of invasive forms of Toxoplasma gondii, Leishmania amazonensis, and Trypanosoma cruzi by atomic force microscopy and surface potential spectroscopy. We found that the specific part of the protozoan which makes initial contact with the host cell is positively charged. This indicates that the positive charge at the site of contact facilitates binding of the invasive protozoan to negatively charged host cells.

Animals↗

PubMed2001

The usefulness of laparoscopy-assisted distal gastrectomy in comparison with that of open distal gastrectomy for early gastric cancer.

BACKGROUND: The technique of laparoscopy-assisted distal gastrectomy (LADG) was developed for early gastric cancer, but its feasibility and the associated clinical outcome remain unclear. METHODS: We reviewed 24 patients who underwent LADG (LADG group) and 35 patients who underwent traditional open distal gastrectomy (ODG group) for early gastric cancer in our hospital, and compared the clinical data of the two groups. RESULTS: The clinical and pathological backgrounds of the patients in the two groups were similar. The duration of surgery was not significantly different between the two groups, but the blood loss in the LADG group was significantly less than that in the ODG group. The number of removed lymph nodes was not significantly different between the two groups. The times to the first passing of flatus, first walking, and the restarting of oral intake; the length of hospital stay; and the duration of epidural analgesia were significantly shorter in the LADG group. The morbidity rate in the LADG group was lower than that in the ODG group. CONCLUSIONS: LADG is a safe and minimally invasive surgical technique, after which we can expect a faster recovery.

Female↗

PubMed2001

Multicentric occurrence of esophageal cancer after gastrectomy: a preliminary report.

The effect of gastrectomy on the subsequent development of esophageal cancer was investigated, focusing on its multicentric occurrence. We retrospectively evaluated 28 patients who underwent subtotal esophagectomy for intrathoracic esophageal cancer between 1985 and 1999. They were divided into two groups according to whether or not they had previously undergone a gastrectomy: group 1, comprising 7 patients who had undergone gastrectomy and group 2, comprising 21 patients who had not. Clinical profiles of the patients were obtained from the medical records and the whole resected esophagus was histopathologically examined. The interval between gastrectomy and esophagectomy in group 1 was significantly shorter in the patients who had undergone gastrectomy for gastric cancer than in those who had undergone gastrectomy for a peptic ulcer, and also in the patients for whom anastomosis had been performed by Billroth I compared with Billroth II. The patients in group 1 were significantly younger than those in group 2. The multiple occurrence of esophageal cancer was found in 4 of 5 patients (80%) in group 1, and in 2 of 18 patients (11%) in group 2, with significantly higher frequency being seen in group 1. More than two coexisting cancer lesions apart from the primary tumor were detected in all four patients. Histological examination of all the coexisting cancer lesions showed well-differentiated squamous cell carcinoma confined within the superficial mucosal layer. No significant differences were noted in the location of the coexisting lesions between the oral and anal side of the primary tumors. Squamous dysplasia was randomly observed, especially around the cancer lesions. These findings suggest that gastrectomy precipitated subsequent chronic gastroesophageal reflux which in turn induced the development of squamous dysplasia and carcinoma at multiple locations in the esophagus.

Aged↗

PubMed2001

Selection of stabilized 3-isopropylmalate dehydrogenase of Saccharomyces cerevisiae using the host-vector system of an extreme thermophile, Thermus thermophilus.

A leuB strain of Thermus thermophilus TTY1, was transformed with a plasmid vector that directed expression of 3-isopropylmalate dehydrogenase (IPMDH) of Saccharomyces cerevisiae encoded by the LEU2 gene. The original strain could not grow at 50 degrees C without leucine, probably because of the low stability of S. cerevisiae IPMDH. The mutants that could grow without leucine were selected at 50 degrees, 60 degrees, 62 degrees, 65 degrees, 67 degrees, and 70 degrees C, step by step. All the mutant strains except for one isolated at 50 degrees C accumulated mutations. Mutations were serially accumulated: Glu255Val, Asn43Tyr, Ala62Thr, Asn110Lys, and Alal 12Val, respectively, at each step. The analyses of residual activity after heat treatment and the denaturation profile as monitored by circular dichroism showed that thermal stability was increased with accumulation of the mutations. The kinetic parameters of most mutant enzymes were similar to those of the wild type. However, some mutant enzymes showed a reverse correlation between stability and activity: the enzymes with a large increase in thermal stability showed lower activity. Although the wild-type enzyme is unstable in the absence of glycerol, the stabilizing effect of glycerol was not observed for all the mutant enzymes containing the Glu255Val substitution, which is assumed to be located at the hydrophobic interface between two subunits.

Cloning, Molecular↗

PubMed2001

Adsorption mechanism of hexavalent chromium by redox within condensed-tannin gel.

We have proposed a new recovery system of hexavalent chromium Cr(VI) that is of great toxicity utilizing condensed-tannin gels derived from a natural polymer with many polyhydroxyphenyl groups. The adsorption mechanism of Cr(VI) to the tannin molecules was clarified. The adsorption mechanism consists of four reaction steps; the esterification of chromate with tannin molecules, the reduction of Cr(VI) to trivalent chromium Cr(III), the formation of carboxyl group by the oxidation of tannin molecules and the ion exchange of the reduced Cr(III) with the carboxyl and hydroxyl groups. It was found in this recovery system that a large amount of proton was consumed accompanied with the reduction of Cr(VI) so that the acidic solution containing Cr(VI) was transferred automatically to neutral one by choosing an appropriate initial pH. The carboxyl group which was created by the oxidation of tannin molecules parallel to the reduction of Cr(VI) to Cr(III) contributed to an increase in the ion-exchange sites of the reduced Cr(III). The maximum adsorption capacity of Cr(VI) reached 287 mg Cr/g dry tannin gel under the conditions of 0.77 water content of tannin gel and the initial pH = 2. This adsorption capacity was five to ten times higher than that obtained by the ion exchange between ordinary Cr(III) and tannin molecules for the tannin gels prepared under similar conditions. The system proposed here will provide an important information on a zero-emission-oriented process because it has such advantages as higher adsorption capacity of chromium and lower volume of secondary wastes compared with conventional process.

Adsorption↗

PubMed2001

Rapid removal of dilute lead from water by pyroaurite-like compound.

Rapid removal of dissolved dilute lead (Pb) by pyroaurite-like compound Mg(x)Fe(y)(OH)2(x+y) (CO3(2-))y/2 x mH2O; anionic clay: one of layered double hydroxides) from water was studied through batch and column experiments. The Pb-removal property of the compound was evaluated as a function of concentration of Pb in the treated solution, space velocity (Sv) of the solution in the column packed with the compound, pH of the solution and contaminated humic substance. The compound showed a highly effective Pb-removal property that was comparable to the other conventional adsorbents. The Pb was removed rapidly by the column packed with the compound over the wide range of the Sv. The buffering pH function of the compound contributed to the Pb removal producing weak-alkali atmosphere. The contamination of humic substance in the treated solution reduced the Pb removal largely depending on its amount. The effectiveness of the compound for the rapid Pb removal was confirmed through a series of experiments.

Charcoal↗

PubMed2001

Embryonic development assay with Daphnia magna: application to toxicity of aniline derivatives.

An assay system using Daphnia magna embryos was applied to investigate the adverse effects of aniline derivatives. The data were compared with our previous data for chlorophenols. This new assay provides useful information to evaluate the toxicity of chemicals and the differences in sensitivity between the life stages. The effects of 15 aniline derivatives on embryonic development of D. magna embryos were determined. At the start of exposure, 2-6-h old eggs (between stages 1 and 2, round in shape, diameter approx. 400 microm), were used. In control and solvent control groups, embryonic development from an egg to a free-swimming animal proceeded completely within 3 days with more than 90% hatchability. Median effective concentrations (EC50s) to reduce the numbers hatched were determined and gross morphological abnormalities of hatched animals recorded. Anilines induced no obvious morphological abnormalities and no developmental delay although premature deaths occurred. However, they affected the number of embryos hatching in a dose-dependent manner. In addition, this embryo assay was more sensitive to aniline derivatives (except for aniline) than acute juveniles immobilization assay. Ratios of 48-h EC50 (juvenile)/3-day EC50 (embryo) for eight anilines were greater than 5.0. Particularly, the ratios of 4-methyl-, 4-ethyl- and 3-methylaniline were 77, 23 and 11, respectively. EC50s for embryos and juveniles were poorly correlated (r = 0.41). This indicated that the sensitivities of the two life stages were different to the effects of anilines. EC50s were poorly correlated (r = -0.097) with the log Kow (1-octanol/water partition coefficient). These results were compared with previous results for phenols.

Aniline Compounds↗