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Biomedical subjects

N Murayama

Publications and source records attributed to N Murayama.

At least 37 records · Page 2Linked to original sources
PubMed2000

cDNA cloning of bradykinin-potentiating peptides-C-type natriuretic peptide precursor, and characterization of the novel peptide Leu3-blomhotin from the venom of Agkistrodon blomhoffi.

A cDNA clone, 1.8 kb long, was isolated from a venom gland cDNA library of Agkistrodon blomhoffi that encodes a large plurifunctional precursor composed of 263 amino-acid residues. Nucleotide sequence analysis of this clone revealed that sequences which code for blomhotin and a novel peptide Leu3-blomhotin are located in the N-terminal region of the precursor polypeptide, followed by four tandemly aligned sequences which code for three types of bradykinin-potentiating peptide. In the C-terminal region, the sequence for the C-type natriuretic peptide was located along with a preceding processing signal. The deduced amino-acid sequences for the four bradykinin-potentiating peptides coincided exactly with previously known sequences for potentiator B, potentiator C and potentiator E. The actual Leu3-blomhotin peptide was subsequently isolated from the venom of A. blomhoffi and characterized. Leu3-blomhotin possesses contractile activity in isolated rat stomach fundus smooth muscle in the same manner as blomhotin. Furthermore, it was shown that blomhotin and Leu3-blomhotin retained activity to inhibit the angiotensin-converting enzyme.

Amino Acid Sequence↗
PubMed2000

Pharmacokinetics of the anticoagulant 14C-DX-9065a in the healthy male volunteer after a single intravenous dose.

1. The plasma pharmacokinetics, excretion and metabolism of DX-9065a were studied in the healthy male Caucasian volunteer after a single intravenous dose of 10 mg 14C-labelled DX-9065a. 2. At the end of a 1 h infusion, the mean plasma concentration of total radioactivity was 380 ng ml(-1) (equivalent to unchanged DX-9065). Thereafter, it decreased in a bi-exponential manner and was below the detection limit by 48 h after dosing. The half-life for the distribution phase was 6.93 h. 3. The total radioactivity recovered in urine and faeces by 336 h post-dose was 83.8% of the administered dose, with excretion ongoing at the end of the 14-day collection. The major route of excretion was via urine, accounting for a mean of 77.6% of the administered radioactivity. The urinary excretion profile was biphasic, consisting of rapid (0-24 h) and slow (24-336 h) phases. A large renal clearance suggested that renal tubular secretion might contribute to the excretion of DX-9065 via urine. 4. No metabolite peaks in the radio-HPLC chromatograms of urine samples were detected, indicating that biotransformation of DX-9065 does not play a significant role in the elimination of DX-9065 in man.

Adult↗
PubMed2000

Metabolic activation of o-phenylphenol to a major cytotoxic metabolite, phenylhydroquinone: role of human CYP1A2 and rat CYP2C11/CYP2E1.

1. The in vitro metabolic activation of o-phenylphenol has been evaluated as yielding a toxic metabolite, 2,5-dihydroxybiphenyl (phenylhydroquinone), by p-hydroxylation in liver microsomes of rat and human. The involvement of rat CYP2C11, CYP2E1 and human CYP1A2 in the p-hydroxylation of o-phenylphenol is suggested. 2. 2,3- and phenylhydroquinone, which induced DNA single-strand scission in the presence of 1 microM CuCl2, were the most cytotoxic chemicals examined to cultured mammalian cell lines among o-phenylphenol, m-phenylphenol, p-phenylphenol, 2,2'-, 4,4'-, 2,3- and phenylhydroquinone. 3. Rat and human liver microsomes catalysed the formation of phenylhydroquinone, but not 2,3-dihydroxybiphenyl, using o-phenylphenol as a substrate. A higher rate of metabolic activation of o-phenylphenol was observed with livers of the male than the female rats by 5.6- and 2.6-fold respectively. 4. Inhibitory antibodies against the male-specific CYP2C11 inhibited hepatic o-phenylphenol p-hydroxylation in the male F344 and Sprague-Dawley rat by > 70%. Liver microsomes from the isoniazid-treated rats produced 1.8- and 3-fold induction of o-phenylphenol p-hydroxylation and chlorzoxazone 6-hydroxylation (a CYP2E1-dependent activity) respectively. 5. Human CYP1A2, expressed by baculovirus-mediated cDNA expression systems, exhibited a remarkably higher capacity for o-phenylphenol p-hydroxylation at concentrations of 5 (> 5-fold), 50 (> 2-fold) and 500 microM (> 2-fold) than CYP2A, CYP2B, CYP2Cs, CYP2D6, CYP2E1 and CYP3A4 on the basis of pmol P450. 6. Among various CYP inhibitors tested here, 7,8-benzoflavone and furafylline, typical human CYP1A2 inhibitors, inhibited the microsomal p-hydroxylation of o-phenylphenol in human livers most potently by 70 and 50% respectively. 7. The results thus indicate the involvement of rat CYP2C11/CYP2E1 and human CYP1A2 in the hepatic p-hydroxylation of o-phenylphenol.

Animals↗
PubMed2000

Altered expression of amyloid precursors proteins after traumatic brain injury in rats: in situ hybridization and immunohistochemical study.

The expression of alternatively spliced mRNAs for amyloid precursor protein (APP) isoforms and their translation products were examined in the rat cerebral cortex 1, 3, 6, and 12 h and 1, 3, and 7 days (n = 4-5 in each group) after fluid-percussion brain injury. In situ hybridization studies demonstrated that the expression of APP695 mRNA decreased in and around the damaged area of the cerebral cortex exposed to fluid-percussion injury 1 h after the insult. On the other hand, APP751/770 mRNAs were increased in the regions surrounding the damaged cortical areas 1 day after the injury. An increase of immunoreactive APP was detected in the regions around the damaged cortical areas 3 h after traumatic injury and maintained for the following 3 days. The APP immunoreactivity in the damaged cortices declined to the level of sham-operated animals by post-experimental day 7. Using an anti-amyloid beta (Abeta) protein (17-24) antibody, no deposits of immunoreactive Abeta (17-24) were observed in any of the samples examined in these experiments. These results suggest that the induction of Kunitz-type protease inhibitor (KPI) domain-containing APP mRNAs and the increased accumulation of APP are involved in the physiological and neuropathological responses of brains under various neurodegenerative conditions, including head trauma.

Alternative Splicing↗
PubMed2000

[Antibody induction and frequency of adverse reactions to influenza vaccines in the elderly].

A total of 1,223 elderly people in nursing homes in Niigata Prefecture, Japan, were immunized with one or two doses of commercial trivalent split vaccine formulation, against strains including A/HN, A/H3N2 and B for three seasons (1996-1999). The frequencies of adverse reactions and antibody induction were assessed. Frequent side effects of vaccination were local reactions such as redness and tenderness at the site of injection, but there were no serious reactions, suggesting that the vaccine was quite safe for the elderly. Furthermore, antibody induction by immunization was relatively high and independent of the degree of activities of daily living (ADL). Annual repeated influenza vaccination did not diminish protection against influenza. However, antibody induction against antigens was insufficient in the 1997/1998 season, and further improvement in the combination of quantities of the four included antigens may by required. A booster dose after the first dose did not enhance immune responses in the nursing staff, and the one dose method appeared to be indicated for the elderly.

Aged↗
PubMed2000

Urinary excretions of albumin and type IV collagen in normotensive and hypertensive subjects.

Plasma albumin leaks into urine as a result of glomerular hypertension and basement membrane injury, while urinary type IV collagen derives from mesangial matrix and glomerular basement membrane. The purpose of this study was to elucidate the pathophysiological significance of these urinary microproteins as an indicator of cardiovascular organ injuries in hypertension. In health-checkup participants without diabetes, proteinuria, or microhematuria, and who were not being treated for hypertension or any other disease at the time of enrollment, urinary albumin and type IV collagen were measured and their relations to organ injuries and cardiovascular risk factors were evaluated. Of 1,079 subjects (40- to 65-year-old; 256 men and 823 women) enrolled in the study, 120 (11.1%) had untreated hypertension exceeding 140/90 mmHg. Urinary albumin was positively correlated with both age (r=0.16, p<0.001) and systolic blood pressure (r=0.27, p<0.001). Urinary type IV collagen was not only positively correlated with age (r=0.12, p<0.001) and diastolic blood pressure (r=0.14, p<0.001) but also negatively correlated with blood hemoglobin (r=-0.12, p<0.001). Urinary albumin, but not type IV collagen, had a significant relation to electrocardiographic signs of left ventricular hypertrophy (p=0.012) and retinal arteriosclerosis on fundoscopy (p <0.001). Thus both albumin and type IV collagen would seem to have increased in association with age and hypertension in this cohort. It is suggested that urinary albumin is an indicator not only of renal injury, but also possibly of development of cardiac hypertrophy and arteriosclerotic changes. Urinary type IV collagen, on the other hand, may be associated with renal tissue injuries that affect erythrokinetics.

Adult↗
PubMed2000

[Effect of beclomethasone increment on airflow limitation in asthmatic children treated with high dose beclomethasone].

In order to evaluate the effect of higher dose BDP therapy (1200-1660 micrograms/day), we studied 12 asthmatic children (mean age 9.7 years-old) with airflow limitation on respiratory function test who were asymptomatic with high-dose BDP therapy (800 micrograms/day). After 4 weeks of higher dose BDP therapy, FVC, FEV1 and V50 were significantly improved, but those improvement were insufficient compared with those after salbutamol inhalation. The personal best values after salbutamol inhalation were not different in every parameter of respiratory function test between BDP 800 micrograms/day and 1200 micrograms/day. We conclude that less than 800 micrograms of daily BDP is generally adequate for prevention in most asthmatic children, because higher dose BDP therapy is no more effective on respiratory function in those treated with 800 micrograms of daily BDP, and that the best value of respiratory function after salbutamol inhalation is not always a goal of high dose BDP therapy.

Anti-Asthmatic Agents↗
PubMed2000

[New protocol for memory-related potential].

A new P300 testing protocol for evaluating memory function is proposed. Four stimuli (S1, S2, S3 and S4) are presented to the subject at 1.5 sec intervals and the subject is instructed to judge whether S4 was the same (80%) or not (20%) as S1, as well as whether S3 was the same (80%) or not (20%) as S2. The S2-S3 comparison acts as an attention shifting mechanism, and by inserting this comparison between S1 and S4, the subject must memorized S1 at the memory site in the brain until S4 is presented. This protocol was performed using both auditory and visual stimulations with 24 college students (age range: 19-28 years old) and a patient (23 years old) with bilateral medial temporal lobe lesions caused by limbic encephalitis. The P300 brain potentials after S3 and S4 were compared. The Wechsler memory scale-revised (WMS-R) test was also assessed in all subjects. The latency of P300 after S4 had a significantly (p < 0.01) longer than that after S3. The latency of P300 after S4 in the patient, who showed the severe auditory as well as the mild visual memory impairment, was longer than the mean + 2 SD in the normal subjects for auditory stimuli, but not for visual stimuli, whereas the latency of P300 after S3 in the patient was longer than the mean + 2 SD in the normal subjects only for visual stimuli. The brain potential after S4 might be more reflective of a degree of memory disorder as compared with that after S3. Furthermore, the latency of P300 after S4 showed a more significant correlation with some WMS-R scores (verbal memory, general memory and verbal delay) than the latency of P300 after S3. These results suggest that measuring the P300 latency after attention shifting in the new protocol is useful for the evaluation of memory functions.

Acoustic Stimulation↗
PubMed2000

Biofeedback training for detrusor overactivity in children.

PURPOSE: We evaluated biofeedback training for incontinence due to detrusor overactivity in children. MATERIALS AND METHODS: Included in our study were 22 boys and 17 girls with a mean age of 11.2 years. We noted nighttime incontinence in 3 patients, nighttime incontinence and daytime urinary symptoms in 26, and daytime incontinence in 10. All patients had detrusor overactivity and incontinence refractory to conventional treatment, including bladder training, tricyclic antidepressants, anticholinergics, desmopressin and/or conditioning therapy. Urodynamic study was performed using an 8Fr double lumen transurethral catheter for cystometry, a double balloon transrectal catheter for rectal pressure and external anal sphincter pressure measurement, and surface electrodes for sphincter electromyography. During biofeedback training patients were instructed to contract the anal sphincter without raising abdominal pressure to inhibit overactive bladder contractions. Biofeedback training was repeated monthly until cystometry revealed a stable bladder or lower urinary tract symptoms improved considerably. RESULTS: Four patients were lost to followup. Of the remaining 35 children urinary symptoms were cured in 23 and improved in 4. Urodynamic studies after 6 months of biofeedback training in 33 cases showed that bladder overactivity disappeared in 10 and improved in 18. Bladder capacity at the initial desire to void and maximum cystometric capacity increased significantly (p = 0.0115 and <0.0001, respectively). Detrusor-sphincter dyssynergia in 2 patients before biofeedback training resolved in each after therapy. CONCLUSIONS: Biofeedback training for detrusor overactivity is effective even in pediatric cases refractory to conventional treatment.

Biofeedback, Psychology↗
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

Tolerability, pharmacokinetics, and pharmacodynamics of DX-9065a, a new synthetic potent anticoagulant and specific factor Xa inhibitor, in healthy male volunteers.

OBJECTIVE: The aim of this study was to assess the tolerability, pharmacokinetic and pharmacodynamic properties of DX-9065a, a novel low-molecule specific factor Xa inhibitor in healthy male volunteers. METHODS: DX-9065a was intravenously administered to healthy male Japanese volunteers at doses of 0.625 to 30 mg. The drug concentrations in plasma and urine were measured and pharmacokinetic parameters were calculated. Coagulation time and bleeding time were also measured. RESULTS: No serious adverse event was observed during or after administration of DX-9065a. The pharmacokinetics of DX-9065a in human subjects after intravenous dosing was linear. The simulated plasma concentrations of DX-9065 were well in accordance with the observed values. Though prolongation of coagulation times was dependent on plasma concentration of DX-9065, bleeding time did not increase even at the highest plasma concentration of 1640 ng/mL. CONCLUSIONS: DX-9065a had a good correlation between linear pharmacokinetics and pharmacodynamics after intravenous administration in humans.

Adult↗
PubMed1999

Seasonal fluctuation in energy balance among farmers in Northeast Thailand: the lack of response of energy intake to the change of energy expenditure.

OBJECTIVE: The study aimed to clarify the seasonal fluctuations in energy balance and their factors among rice-growing farmers in Northeast Thailand whose rice production was enough to their food energy demand. DESIGN: Prospective and repeated measurements in the field. SETTING: A rain-fed rice-farming village. SUBJECTS: Eight pairs of husband and wife. INTERVENTIONS: In each of four periods in a year, anthropometry, energy expenditure survey with heart-rate monitoring and minute-by-minute activity recording, and food consumption survey were conducted for each subject for 4 days. RESULTS: The change of body weight was modest but differed significantly (P < 0.001) between pre-harvest and post-harvest seasons: 1.3 kg (2.3%) for males, 2.5 kg (4.3%) for females. Total energy expenditure (TEE) fluctuated markedly between the 4 seasons (P < 0.001 for males and females), but total energy intake (TEI) fluctuated to lesser extents (P < 0.05 for females only). In relation to energy expenditure, physiological indicators (except respiratory quotient) did not fluctuate throughout the year but behavioral indicators did. The changes in body weight were significantly correlated with the changes in TEE (r = 0.60, P < 0.05 for males; r = 0.83, P < 0.01 for females) but not with the changes in TEI; TEE and TEI were not correlated. CONCLUSIONS: The modest seasonal changes in body weight among rain-fed rice farmers in Northeast Thailand were caused by the lack of response of TEI to the change of TEE.

Adult↗
PubMed1999

Two outbreaks of influenza A (H3N2) in a Japanese nursing home in the winter of 1996-1997, with differing vaccine efficacy.

Sixty of 128 (46.9%) residents of a nursing home were immunized with two doses of the trivalent split influenza vaccine. They developed 7.4-11.5-fold antibody increases, with a 69-82% protection rate, presenting good immune response rates to the influenza vaccine. Two outbreaks of influenza A (H3N2) occurred. There were no significant antigenic differences among the vaccine strain and the strains isolated from both outbreaks in haemagglutination-inhibition tests, suggesting that the second might have been a reoccurrence. There were no residents who were infected in both outbreaks. The vaccine efficacy against clinical illness in the first outbreak of typical influenza-like-illness (ILI) was 51% (relative risk: 0.49), and the febrile period was reduced significantly by vaccination. In the second outbreak, however, in which all patients had atypical ILI with a high fever but not respiratory symptoms, vaccine efficacy was not apparent for unknown reason.

Aged↗
PubMed1999

Effect of long-term treatment with inhaled beclomethasone dipropionate on growth of asthmatic children.

The effect of long-term inhaled steroid therapy on linear growth in asthmatic children is still a point of controversy. We tried to clarify the effect of long-term treatment with inhaled beclomethasone dipropionate (BDP) on linear growth and final height of asthmatic children. Height data measured annually from 12 years (beginning at age 10 years in most patients) to 20 years of age were retrospectively collected from clinical records in 97 moderate to severe asthmatics (49 boys, 48 girls) born in 1971-1975 who were observed regularly for more than 8 years at our outpatient clinic. Data were expressed as standard deviation scores and were compared between patients treated with BDP (30 boys and 31 girls, mean daily dosages were 300-800 microg) and without BDP. Growth delay in the early period of puberty and catch-up growth in the late period of puberty was found in both patients treated with and without BDP. The age of onset of treatment with BDP inhalation had no influence on linear growth, and asthmatic children receiving optimum treatment eventually attained standard final height for their age group. Long-term treatment with inhaled BDP in conventional doses does not significantly impair linear growth in asthmatic children.

Administration, Inhalation↗
PubMed1998

Purification and characterization of a kinin-releasing and fibrinogen-clotting serine proteinase (KN-BJ) from the venom of Bothrops jararaca, and molecular cloning and sequence analysis of its cDNA.

Two forms of a proteinase, KN-BJ 1 and 2, were purified to homogeneity from the venom of Bothrops jararaca. In SDS/PAGE reduced KN-BJ 1 and 2 migrated as single bands with molecular masses of 38 kDa and 39 kDa. The two enzymes have similar N-terminal amino acid sequences and specific activities on synthetic chromogenic substrates, and both release bradykinin from bovine low-molecular-mass kininogen. KN-BJ 1 and KN-BJ 2 clot fibrinogen with specific activities of 245 NIH U/mg and 219 NIH U/mg, releasing only fibrinopeptide A. The amidolytic, kinin-releasing and coagulant activities are inhibited by phenylmethylsulfonyl fluoride, demonstrating that KN-BJ is a serine proteinase. Benzamidine derivatives, which are competitive inhibitors of trypsin-like proteinases, also inhibited the amidolytic activity of KN-BJ. A cDNA clone (HS104, 2.2 kb) has been isolated from a cDNA library of B. jararaca venom glands with an ORF of 771 bp. The deduced amino acid sequence contains segments that are identical to the sequences of the N-terminus and three tryptic peptides of KN-BJ 2. Therefore, the cDNA is believed to represent the gene of KN-BJ 2. The deduced amino acid sequence indicates that KN-BJ 2 is synthesized as a prezymogen of 257 amino acids with a putative signal peptide of 18 amino acids and an activating peptide of six amino acid residues. The sequence of 233 amino acids representing the mature enzyme exhibits high similarity to sequences of serine proteinases isolated from crotalid venoms.

Amino Acid Sequence↗
PubMed1998

Cloning and expression analysis of a cDNA coding for a dexamethasone-inducible cytochrome P450 in Xenopus laevis liver.

We previously purified a cytochrome P450 (P450) from liver microsomes of adult female Xenopus laevis. In this study, we screened a cDNA library of Xenopus liver to isolate the cDNA clone coding for this P450. The 5'-end of the resultant cDNA was truncated at the N-terminal region and extended by method of rapid amplification of cDNA end to give the complete coding sequence. Amino acid sequence showed this clone to be 36% to 55% identical to members of the CYP2 family and less than 31% identical to members of other gene families, and to belong to the CYP2Q subfamily. This gene is expressed constitutively in the livers of adult male and female frogs, and is significantly induced by dexamethasone administration.

Amino Acid Sequence↗