Biomedical subjects

S Higuchi

Publications and source records attributed to S Higuchi.

At least 55 records · Page 3Linked to original sources

PubMed1999

Molecular cloning and sequence analysis of cDNAs coding for 3-methylcholanthrene-inducible cytochromes P450 in Xenopus laevis liver.

Liver microsomes of Xenopus laevis were investigated for specific cytochrome P450s (CYPs) that would be inducible in response to the administration of either 3-methylcholanthrene (3MC) or beta-naphthoflavone (BNF), potent inducers for mammalian CYP1A. When probed with antibodies raised against rat CYP1A1, a 54-kDa protein was detected after administration of polycyclic aromatic hydrocarbons. However, there was no immunoreactive protein in microsomes from untreated frogs. In order to obtain structural information about this CYP1A-like protein, a liver cDNA library of 3MC-treated frog was constructed and screened using a fragment of rat CYP1A2 cDNA under low stringency conditions. We have isolated two cDNA clones (MC1 and MC2) with inherent features of the CYP1A subfamily. The sequence determination revealed that both of them coded for polypeptides composed of 526 amino acid residues, which differed from each other by 30 amino acids. A comparison with other mammalian CYP enzymes demonstrated that both of the sequences share 55 to 63% identity with the sequences of CYP1A family members. Northern blot analysis and RT-PCR results further demonstrated that two discrete transcripts corresponding to clones MC1 and MC2 are indeed inducible in the frog liver by treatment with 3MC or BNF. The names CYP1A6 and CYP1A7 were given to clones MC1 and MC2, respectively.

Animals↗

PubMed1999

Bradykinin-potentiating peptides and C-type natriuretic peptides from snake venom.

Cloning of cDNAs encoding bradykinin-potentiating peptides (BPPs)-C-type natriuretic peptide (CNP) precursor or its homologue was performed for cDNA libraries of Bothrops jararaca (South American snake), Trimeresurus flavoviridis, Trimeresurus gramineus and Agkistrodon halys blomhoffi (Asian snakes), all belonging to Crotalinae subfamily. Each cDNA library was constructed from the venom glands of a single snake to preclude ambiguity by intraspecies variation in venom components. Thirteen positive clones derived from B. jararaca were divided into two types depending on restriction sites. Differences in the nucleotide sequence arise at three locations and two of them accompanied amino acid conversions. Despite the differences, both types of cDNA clones encode the BPP-CNP precursor of 256 amino acid residues. Sequence analysis demonstrated that cDNA clones from three Asian snakes encode homologues of the BPP-CNP precursor from B. jararaca. In a precursor polypeptide, a signal sequence (approximately 25 aa) at the N-terminus is followed by sequences of BPP or the analogue (5-13 aa) with flanking spacer sequences (indefinite number of aa), an intervening linker sequence (approximately 144 aa) with unidentified function, and a CNP sequence (22 aa) with a preceding processing signal sequence (10 aa). cDNA clones from A. halys blomhoffi encode two distinct peptides in place of BPP, and T. flavoviridis and T. gramineus were shown to have considerably different sequences in the BPP domain from those known as BPP sequences. The present results provide evidence for a wide distribution of the orthologous gene expressing a series of bioactive peptides among Crotalinae subfamily.

3' Untranslated Regions↗

PubMed1999

Suppression of FRP-1/CD98-mediated multinucleated giant cell and osteoclast formation by an anti-FRP-1/CD98 mAb, HBJ 127, that inhibits c-src expression.

When anti-CD98 mAb 6-1-13, 4-5-1, or 38-2-2 was added to the culture fluids of monocytes, extensive cell aggregation and polykaryocyte formation were induced. These multinucleated giant cells were tartrate-resistant acid phosphatase (TRAP) positive. On the other hand, when monocytes were incubated with another anti-CD98 mAb, HBJ 127, polykaryocyte formation was not detected, although extensive cell aggregation was induced. When HBJ 127 and 6-1-13 were simultaneously added to the culture fluids, anti-CD98 mAb-induced cell fusion was inhibited almost completely. HBJ 127 suppressed formation of 6-1-13-induced cell fusion in a dose-dependent manner. If, however, HBJ 127 was added after incubation of monocytes with mAb 6-1-13 for 6 h, an appreciable degree of TRAP-positive polykaryocyte formation was found. The bindings of 6-1-13 and HBJ 127 were not mutually competed. When monocytes were incubated with 6-1-13 or HBJ 127, 6-1-13 induced c-src mRNA, while HBJ 127 did not. Furthermore, when monocytes were incubated with both 6-1-13 and HBJ 127, c-src mRNA could not be detected, showing that HBJ 127 suppresses c-src expression. Therefore, CD98-mediated osteoclast formation can be regulated by modification of CD98 system.

Antibodies, Monoclonal↗

PubMed1999

Rapid characterization of urinary metabolites of pibutidine hydrochloride in humans by liquid chromatography/electrospray ionization tandem mass spectrometry.

The metabolic products of pibutidine hydrochloride, a new H(2)-receptor antagonist, in human urine after oral administration of 40 mg/man were characterized by high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) with electrospray ionization (ESI). Two-stage collision-induced dissociation (CID) experiments, with in-source CID by increasing the octapole offset voltage and collision-cell CID, were performed in order to develop a very rapid screening procedure that enhanced selectivity toward pibutidine-related compounds. It was possible to detect metabolites of pibutidine directly from a crude biological matrix without prior extraction, enabling confirmation of the identity of eight metabolites in urine. In addition, the linear range in ESI for pibutidine-related compounds was studied to determine the urinary excretion of pibutidine and its metabolites in humans.

Chromatography, Liquid↗

PubMed1999

Plasma protein binding of tamsulosin hydrochloride in renal disease: role of alpha1-acid glycoprotein and possibility of binding interactions.

OBJECTIVE: To investigate the factors that affect the plasma protein binding of tamsulosin in patients with lowered renal function compared with that in healthy subjects and to evaluate the possibility of binding interactions. METHODS: Blood was donated from patients with renal dysfunction and from healthy subjects. The binding of 14C-tamsulosin to plasma proteins was determined by the ultrafiltration method. In addition, plasma protein binding interactions were investigated between tamsulosin and other drugs used concomitantly. RESULTS: The mean percentage of unbound 14C-tamsulosin was 0.90% in the healthy subjects (control) and was 0.71% in the patients. The unbound fraction in the patients with alpha1-acid glycoprotein (alpha1-AGP) levels over 0.9 mg/ml was significantly lower than that in the healthy subjects. In contrast, the unbound fraction in the patients with alpha1-AGP levels less than 0.7 mg/ml, which is the mean normal level, was almost equal to the control levels. A significant correlation existed between the Cb/Cu of tamsulosin and plasma alpha1-AGP level (r2 = 0.580, P < 0.001), while no correlation existed between the Cb/Cu and plasma albumin level (r2 = 0.021, P = 0.381) in both groups. No apparent binding interactions were observed between tamsulosin and the other drugs examined. CONCLUSIONS: Tamsulosin is highly bound to alpha1-AGP. The extent of plasma protein binding of tamsulosin correlated with the alpha1-AGP level but not with the albumin level. Furthermore, there appears to be no or little possibility of binding interactions between tamsulosin and other drugs in clinically concomitant use, despite its strong binding to alpha1-AGP.

Adrenergic alpha-Antagonists↗

PubMed1999

Inhibitory effect of TS-962 on the formation of early atherosclerotic lesions in high fat-fed hyperlipidemic hamsters.

The hypocholesterolemic and anti-atherosclerotic effect of TS-962, a specific ACAT inhibitor, was investigated in a hamster model fed a high fat diet containing 10% coconut oil and 0.05% cholesterol. Lipid accumulated atherosclerotic lesions were detected by using oil red O staining in the lesion-prone aortic arch. A high dose, estimated to be 15 mg/kg, of TS-962 decreased serum cholesterol to normal levels with reduction of liver cholesterol contents below normal levels, and as a consequence, entirely inhibited the lipid accumulation in the aortic arch. Furthermore, a low dose, estimated to be 1.5 mg/kg, of TS-962 remarkably inhibited aortic lipid accumulation by 73% compared with the control group, without changing either serum cholesterol level or liver cholesterol content. These findings suggest that TS-962 is effective in the primary prevention of atherosclerosis by directly suppressing the formation of foam cells in arteries.

Acetamides↗

PubMed1999

Gene expression during osteoclast-like cell formation induced by antifusion regulatory protein-1/CD98/4F2 monoclonal antibodies (MAbs): c-src is selectively induced by anti-FRP-1 MAb.

Human blood monocytes can differentiate into osteoclast-like cells when they are cultured in the presence of anti-FRP-1. Messenger (mRNA) expression of markers related to osteoclasts was analyzed during differentiation of osteoclasts from monocytes. As markers related to osteoclasts, we selected cathepsin-K, carbonic anhydrase (CA) II, vacuolar H(+)-ATPase (v-ATPase), vitronectin receptor (VNR), tartrate-resistant acid phosphatase (TRAP), osteopontin (OPN), galectin-3, c-src, c-fos, and c-fms. The mRNAs other than c-src mRNA were expressed in freshly isolated monocytes or monocytes incubated with control antibody or anti-FRP-1 monoclonal antibody (MAb) for 14 days. Of these mRNAs, cathepsin-K, CA II, v-ATPase, VNR, TRAP, OPN, and c-fms mRNAs were expressed at higher levels in the osteoclast-like cells than those in monocytes cultured with control antibody. On the other hand, galectin-3 mRNA was expressed at lower levels in the osteoclast-like cells, and there was no significant difference in c-fos mRNA expression between the monocytes cultured with control antibody and anti-FRP-1 MAb. c-src mRNA could not be detected in monocytes freshly isolated or incubated with control antibody. Surprisingly, expression of c-src mRNA was induced in monocytes by anti-FRP-1 MAb and was detectable as early as 3 h after anti-FRP-1 MAb treatment, indicating that c-src is selectively induced by anti-FRP-1 MAb treatment. Furthermore, the osteoclast-like cells expressed calcitonin receptor. Receptor activator of NF-kappaB (RANK) mRNA was detectable in freshly isolated monocytes or monocytes cultured with control antibody or anti-FRP-1 MAbs. Maximal expression of RANK was observed in osteoclast-like cells. On the other hand, no receptor activator of NF-KB ligand (RANKL) mRNA was detectable in any of the samples, suggesting that anti-FRP-1 mAb can induce osteoclast-like cells from blood monocytes without RANKL.

Antibodies, Monoclonal↗

PubMed1999

Association of a polymorphism of the 5HT2A receptor gene promoter region with alcohol dependence.

Approximately 10% of Japanese alcoholics develop their disease despite having an inactive form of aldehyde dehydrogenase-2 (ALDH2), known as a genetic deterrent of heavy drinking due to adverse reactions after drinking. Such alcoholics are considered to be advantageous in genetic research because they should show reduced heterogeneity and possess genetic factors conferring susceptibility to alcohol dependence. Examination of the -1438 A/G polymorphism of the serotonin 2A (5HT2A) receptor gene in 225 Japanese alcoholics with inactive ALDH2 revealed the presence of significantly more of the G allele than was found in 361 control subjects. The frequency of the G allele in 282 alcoholics with active ALDH2 fell between the G allele frequencies of controls and subjects with inactive ALDH2. These data suggest that although the effect is relatively small, genetic variability in the 5HT2A receptor is involved in the development of alcohol dependence.

Alcoholism↗

PubMed1999

Reliability of the omeprazole hydroxylation index for CYP2C19 phenotyping: possible effect of age, liver disease and length of therapy.

AIMS: To evaluate the reliability of the omeprazole hydroxylation index as a marker for polymorphic CYP2C19 activity in a Japanese population of healthy young subjects (n = 78) and patients with peptic ulcer (n = 72). METHODS: Healthy subjects were administered a single dose of omeprazole (20 mg), whereas patients received 20 mg daily for at least 1 week. The ratio of the serum concentration of omeprazole to hydroxyomeprazole at 3 h postdose was determined and used as a measure of CYP2C19 activity. The CYP2C19 wild type (wt) gene and four mutant alleles associated with the poor metaboliser phenotype of (S)-mephenytoin, CYP2C19*2 in exon 5, CYP2C19*3 in exon 4, CYP2C19m4 in exon 9, and CYP2C19m3 in the initial codon were analysed. RESULTS: In the healthy volunteer study there was complete concordance between genotype and phenotype. However, eight of the patients who had the EM genotype had a high value for their hydroxylation index, and were classified as phenotypic PMs. No CYP2C19m4 and CYP2C19m3 mutations were detected in the eight mismatched patients. They were all genotypic heterozygous EMs, elderly (> or = 65 years) and/or had hepatic disease. Therefore, impaired CYP2C19 activity combined with partial saturation of omeprazole metabolism during multiple dosing may have contributed to the discrepancy between CYP2C19 genotyping and phenotyping. CONCLUSION: Although omeprazole has been used instead of mephenytoin as a probe for polymorphic CYP2C19, it does not appear to be reliable enough for clinical application in Japanese patients.

Adult↗

PubMed1999

Population analysis for the optimization of digoxin treatment in Japanese paediatric patients.

BACKGROUND AND OBJECTIVES: Information about the pharmacokinetics of digoxin in paediatric patients is limited. We therefore aimed to investigate the effects of physiological factors on the digoxin clearance in Japanese paediatric patients. METHOD: We used routinely collected therapeutic drug monitoring data (n=544), derived from the steady-state serum concentrations of digoxin in 181 hospitalized paediatric patients. RESULTS: Of those physiological factors which have been examined in this study, age and total body weight were most closely correlated with digoxin clearance. Data on neonates within the first postnatal month indicated a tendency towards lower clearance for premature neonates than full-term neonates (P<0.01). Digoxin clearance was reduced by spironolactone in patients younger than 4 months (P<0.05). Patients with congestive heart failure showed a lower digoxin clearance than the others (P<0.001). Serum creatinine and gender did not have a statistically significant effect on digoxin clearance. CONCLUSION: Age and total body weight are important factors influencing digoxin clearance in children. Spironolactone affected digoxin clearance and needs to be considered when dosing paediatric subjects.

Age Factors↗

PubMed1999

Interaction of the new histamine H2-receptor antagonist pibutidine hydrochloride with canine cloned H2-receptor expressed cells.

The effect of a new histamine H2-receptor antagonist, pibutidine hydrochloride ((Z)-3-amino-4-{4-{4-[(piperidinomethyl)pyrid-2-yl]oxy} but-2-enylamino}cyclobut-3-ene-1,2-dione monohydrochloride, CAS 126463-66-9, IT-066 displaced the binding of [3H]tiotidine to cells transfected with the wild-type H2-receptor in a concentration-dependent manner. Compared with the 50% inhibitory concentration values (IC50) among five H2-receptor antagonists tested, the value of IT-066 was lowest. The inhibitory effect of IT-066 was enhanced by preincubation of IT-066 with the cells, and preincubation for 60 min increased potency about 2-fold. Famotidine also has such effects. When H2-receptor transfected cells were treated with IT-066 for 30 min, the inhibitory effect of IT-066 on the [3H]tiotidine binding still remained even after the cells were extensively washed. Scatchard plot analysis supported the non-competitive and irreversible action of IT-066. When the canine mutated H2-receptor-expressed cells were used, which have substituted amino acid of 190Alanine (Ala; position: 190th amino acid) for 190Threonine (Thr) in the fifth transmembrane domain, IT-066 also inhibited [3H]tiotidine binding to the cells concentration-dependently. However, in the case of the 190Ala mutated cells, the inhibitory effect of IT-066 attenuated with a decrease in maximal response after washing of the cells. These results show that IT-066 could tightly bind H2-receptor in a time-dependent manner and suggest the possibility that the irreversible inhibition of IT-066 is important in the interaction with 190Thr in the fifth transmembrane domain of H2-receptor.

Alanine↗

PubMed1999

Alcohol consumption as a major risk factor for the rise in liver cancer mortality rates in Japanese men.

BACKGROUND: Age-adjusted liver cancer mortality rates have been increasing for both men and women in Japan since 1970; however, increases in mortality rates in men are much greater than those in women. Hepatitis C virus infections and heavy alcohol consumption are considered to be the major risk factors of liver cancer deaths in Japanese. The purpose of this study is (1) to examine the pattern of liver cancer mortality by gender and birth year to compare those with the pattern of other alcohol-related mortality and (2) to estimate the attributable risk per cent of heavy alcohol consumption for liver cancer deaths in Japanese men. METHODS: Age-specific liver cancer mortality rates by gender were compared with those of cirrhosis mortality rates. Then male-to-female mortality rate ratios were calculated by birth cohort and compared with cirrhosis mortality rate ratios and oesophageal cancer mortality rate ratios. The attributable risk per cent of alcohol consumption for liver cancer death was calculated, using female liver cancer mortality rates as standard rates. RESULTS: Examination of both gender and birth cohort mortality rates revealed that male-to-female liver cancer mortality rate ratios by birth cohort correspond well with those rate ratios for liver cirrhosis and oesophageal cancer mortality. The attributable risk per cent of alcohol consumption for liver cancer deaths in Japanese men was 70%. CONCLUSION: Alcohol consumption is more important than hepatitis C virus infections as a major cause of liver cancer deaths in Japanese men.

Adult↗

PubMed1999

Predictive performance of equations to estimate creatinine clearance from serum creatinine in Japanese patients with congestive heart failure.

Seven methods using patient's age, weight, gender, and serum creatinine concentration were evaluated for mathematical and clinical predictive performance in estimating the creatinine clearance of Japanese patients. We compared the measured and estimated creatinine clearance in 179 hospitalized heart failure patients. The Gates equation was the most biased (mean prediction error, 17.9 mL/min), and the Yukawa equation was the most precise (mean absolute prediction error, 10.4 mL/min), followed by the Jelliffe, Bjornsson, Cockcroft and Gault, and Mawer equations. For all methods, precision was less when serum creatinine concentrations of <0.6 mg/dL were rounded than when serum creatinine concentrations of >/=0.6 mg/dL were rounded. We conclude that in clinical practice where the renal function can vary widely, any of the published formulas can give satisfactory results. The Yukawa formula is concise and gives better results in Japanese patients.

Adolescent↗

PubMed1999

Crystallization and preliminary x-ray diffraction studies of hyperthermostable glutamate dehydrogenase from Thermococcus profundus.

Recombinant glutamate dehydrogenase from a hyperthermophilic archaeon, Thermococcus profundus, was crystallized in the presence of both polyethylene glycol 8000 and lithium sulfate. Four types of crystals having different morphologies appeared in the crystallization trials; however, only one type was suitable for X-ray crystal structure analysis. The crystal belonged to the monoclinic space group P2(1) and the unit-cell parameters were a = 112.99, b = 163.70, c = 133.07 A, beta = 113.46 degrees at 110 K. The calculated V(M) value of 3.42 A(3) Da(-1) was acceptable when one hexamer of the enzyme, which was the physiological functional unit, occupied a crystallographic asymmetric unit. X-ray diffraction intensity data were collected to a resolution of 2.25 A with good statistics at the BL44B2 beamline of SPring-8.

Crystallization↗

PubMed1999

Genetic association between alcohol withdrawal symptoms and polymorphism of CCK gene promoter.

In the central nervous system, cholecystokinin (CCK) is an important neurotransmitter that gives the influences on firings, anxiety, notiception, and dopamine-related behavior. CCK co-exists in the dopaminergic neurons, interacting with dopamine. In this study, we examined the genetic variant -45 C to T substitution of the CCK gene promoter region among 195 healthy Japanese and 174 patients with alcohol withdrawal syndrome (52 delirium tremens, 39 hallucinosis, 20 seizures, and 92 lack of these symptoms) by using polymerase chain reaction-based single-strand conformational polymorphism analysis. Patients with delirium tremens showed a significantly higher frequency of the variant, compared with the controls (chi2 = 4.91, p < 0.03), but patients with other symptoms showed no difference. These data suggested that the individuals possessing allelic mutation (-45T) in the promoter region of the CCK gene might be susceptible to delirium tremens caused by alcohol abuse.

Cholecystokinin↗

PubMed1999

Close association between clearance of recombinant human granulocyte colony-stimulating factor (G-CSF) and G-CSF receptor on neutrophils in cancer patients.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is used to counter chemotherapy-induced neutropenia. Our previous study showed an inverse correlation between serum rhG-CSF levels and the number of circulating neutrophils in cancer patients (H. Takatani, H. Soda, M. Fukuda, M. Watanabe, A. Kinoshita, T. Nakamura, and M. Oka, Antimicrob. Agents Chemother. 40:988-991, 1996). The aim of this study was to clarify the relationship between rhG-CSF clearance and G-CSF receptors on circulating neutrophils. In five cancer patients receiving chemotherapy, a bolus dose of rhG-CSF (5 microg/kg) was injected intravenously during defined phases of posttreatment neutropenia and neutrophilia. Serum rhG-CSF levels were measured by a chemiluminescence enzyme immunoassay and analyzed by moment analysis. G-CSF receptors on neutrophils were detected by flow cytometry with biotinylated rhG-CSF. rhG-CSF clearance was significantly higher at neutrophilia than at neutropenia (1,497 +/- 132 versus 995 +/- 266 ml/h; P < 0.01). The percentage of G-CSF receptor-positive neutrophils, reflecting the number of G-CSF receptors per cell, was low at neutropenia without rhG-CSF therapy (44.5% +/- 22.1%) and high at neutrophilia with rhG-CSF therapy (73. 0% +/- 11.4%; P < 0.01). rhG-CSF clearance closely correlated with the percentage of G-CSF receptor-positive neutrophils (r2 = 0.91; P < 0.0001) and neutrophil count (r2 = 0.72; P < 0.005). Our results indicate that, in cancer patients receiving chemotherapy, rhG-CSF increases the number of G-CSF receptors per cell as well as circulating neutrophil counts, resulting in modulation of its own clearance.

Adjuvants, Immunologic↗

PubMed1999

Pharmacokinetic and pharmacodynamic analysis of subcutaneous recombinant human granulocyte colony stimulating factor (lenograstim) administration.

A total of 72 adult healthy volunteers were administered 1 microgram/kg of rhG-CSF. There was no correlation between Cmax and an increase in peripheral neutrophil count, and there was a negative correlation between AUC and this increase. The mechanism of this is probably based on the correlation between the elimination rate constant (ke) and neutrophil increase. The ke probably has a close relationship with uptake by neutrophil and its progenitor via the G-CSF receptor. An individual with higher ke should therefore show a greater increase in neutrophil count. Therefore, AUC is proportional to the rhG-CSF remainder, that is, the proportion that is not consumed in the course of increasing the neutrophil count. In such a situation, the bioavailability calculated from the AUC is unlikely to indicate the absorbed amount. The authors also analyzed the pharmacokinetics using a two-compartment model with zero-order absorption and first-order elimination. This model was sufficient to obtain a good curve fit, and this demonstrates that the absorption process is not a first-order but a zero-order process. Therefore, there might be an upper limit to the rhG-CSF transfer rate from subcutaneous tissue to blood.

Adjuvants, Immunologic↗

PubMed1999

The complete amino acid sequence of dog beta2-microglobulin.

Dog beta2-microglobulin was purified from the urine of dogs with potassium dichromate induced tubular damage. It was purified by sequential use of anion exchange chromatography, gel filtration chromatography, and reversed-phase high performance liquid chromatography. Comparisons of the amino acid sequence of the dog protein with human, mouse, and rabbit beta2-microglobulin, indicated a high degree of similarity. The dog protein was very similar to human beta2-microglobulin in that it had a molecular weight of 11.8 kDa and contained two half-cystinyl residues. Dog and human beta2-microglobulin were demonstrably different at 24 of the 99 positions compared. The data supported the conclusion that the purified protein was dog beta2-microglobulin and that all four proteins from dog, human, mouse, and rabbit were closely related.

Amino Acid Sequence↗