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Biomedical subjects

N Usami

Publications and source records attributed to N Usami.

At least 19 recordsLinked to original sources
PubMed2001

Genetic alteration of the beta-catenin gene (CTNNB1) in human lung cancer and malignant mesothelioma and identification of a new 3p21.3 homozygous deletion.

The beta-catenin gene (CTNNB1) has been shown to be genetically mutated in various human malignancies. To determine whether the beta-catenin gene is responsible for oncogenesis in thoracic malignancies, we searched for the mutation in 166 lung cancers (90 primary tumors and 76 cell lines), one blastoma and 10 malignant mesotheliomas (two primary tumors and eight cell lines). Among the lung cancers, including 43 small cell lung cancers (SCLCs) and 123 non-small cell lung cancers (NSCLCs), we identified four alterations in exon 3, which is the target region of mutation for stabilizing beta-catenin. One primary adenocarcinoma had a somatic mutation from C to G, leading to an amino acid substitution from Ser to Cys at codon 37. Among the cell lines, SCLC NCI-H1092 had a mutation from A to G, leading to an Asp to Gly substitution at codon 6, NSCLC HCC15 had a mutation from C to T, leading to a Ser to Phe substitution at codon 45, and NSCLC NCI-H358 had a mutation from A to G, leading to a Thr to Ala substitution at codon 75. One blastoma also had a somatic mutation from C to G, leading to a Ser to Cys substitution at codon 37. Among the 10 malignant mesotheliomas, we identified a homozygous deletion in the NCI-H28 cell line. Cloning of the rearranged fragment from NCI-H28 indicated that all the exons except exon 1 of the beta-catenin gene are deleted and that the deletion junction is 13 kb downstream from exon 1. Furthermore, Northern blot analysis of 26 lung cancer and eight mesothelioma cell line RNAs detected ubiquitous expression of the beta-catenin messages except NCI-H28, although Western blot analysis showed that relatively less amounts of protein products were expressed in some of lung cancer cell lines. Our findings suggest that the beta-catenin gene is infrequently mutated in lung cancer and that the NCI-H28 homozygous deletion of the beta-catenin gene might indicate the possibility of a new tumor suppressor gene residing in this region at 3p21.3, where various types of human cancers show frequent allelic loss.

Base Sequence↗
PubMed2001

Identity of dimeric dihydrodiol dehydrogenase as NADP(+)-dependent D-xylose dehydrogenase in pig liver.

Dimeric dihydrodiol dehydrogenases (DDs, EC 1.3.1.20), which oxidize trans-dihydrodiols of aromatic hydrocarbons to the corresponding catechols, have been molecularly cloned from human intestine, monkey kidney, pig liver, dog liver, and rabbit lens. A comparison of the sequences with the DNA sequences in databases suggested that dimeric DDs constitute a novel protein family with 20 gene products. In addition, it was found that dimeric DD oxidizes several pentoses and hexoses, and the specificity resembles that of NADP(+)-dependent D-xylose dehydrogenase (EC 1.1.1.179) of pig liver. The inhibition of D-xylose dehydrogenase activity in the extracts of monkey kidney, dog liver and pig liver, its co-purification with dimeric DD activity from pig liver, and kinetic analysis of the D-xylose reduction by pig dimeric DD indicated that the two enzymes are the same protein.

Alcohol Oxidoreductases↗
PubMed2001

Molecular cloning, expression and tissue distribution of hamster diacetyl reductase. Identity with L-xylulose reductase.

Using rapid amplification of cDNA ends PCR, a cDNA species for diacetyl reductase (EC 1.1.1.5) was isolated from hamster liver. The encoded protein consisted of 244 amino acids, and showed high sequence identity to mouse lung carbonyl reductase and hamster sperm P26h protein, which belong to the short-chain dehydrogenase/reductase family. The enzyme efficiently reduced L-xylulose as well as diacetyl, and slowly oxidized xylitol. The K(m) values for L-xylulose and xylitol were similar to those reported for L-xylulose reductase (EC 1.1.1.10) of guinea pig liver. The identity of diacetyl reductase with L-xylulose reductase was demonstrated by co-purification of the two enzyme activities from hamster liver and their proportional distribution in other tissues.

Acetoin Dehydrogenase↗
PubMed2001

Enzymatic characteristics and subcellular distribution of a short-chain dehydrogenase/reductase family protein, P26h, in hamster testis and epididymis.

A hamster sperm 26 kDa protein (P26h) is strikingly homologous with mouse lung carbonyl reductase (MLCR) and is highly expressed in the testis, but its physiological functions in the testis are unknown. We show that recombinant P26h resembles NADP(H)-dependent MLCR in the tetrameric structure, broad substrate specificity, inhibitor sensitivity, and activation by arachidonic acid, but differs in a preference for NAD(H) and high efficiency for the oxidoreduction between 5alpha-androstane-3alpha,17beta-diol (k(cat)/K(M) = 243 s(-1) mM(-1)) and 5alpha-dihydrotestosterone (k(cat)/K(M) = 377 s(-1) mM(-1)). The replacement of Ser38-Leu39-Ile40 in P26h with the corresponding sequence (Thr38-Arg39-Thr40) of MLCR led to a switch in favor of NADP(H) specificity, suggesting the key role of the residues in the coenzyme specificity. While the P26h mRNA was detected only in the testis of the mature hamster tissues, its enzyme activity was found mainly in the mitochondrial fraction of the testis and in the nuclear fraction of the epididymis on subcellular fractionation, in which a mitochondrial enzyme, isocitrate dehydrogenase, exhibited a similar distribution pattern. The enzyme activity of P26h in the two tissue subcellular fractions was effectively solubilized by mixing with 1% Triton X-100 and 0.2 M KCl, and enhanced more than 10-fold. The enzymes purified from the two tissue fractions exhibited almost the same structural and catalytic properties as those of the recombinant P26h. These results suggest that P26h mainly exists as a tetrameric dehydrogenase in mitochondria of testicular cells and plays a role in controlling the intracellular concentration of a potent androgen, 5alpha-dihydrotestosterone, during spermatogenesis, in which it may be incorporated in mitochondrial sheaths of spermatozoa.

Alcohol Oxidoreductases↗
PubMed2001

Enhanced strand break induction of DNA by resonant metal-innershell photoabsorption.

We determined the number of single and double strand breaks (ssb and dsb) in a DNA-chloroterpyridine platinum complex induced by resonant photoabsorption in the L(III) innershell of a platinum atom. The number of ssb and dsb were measured in supercoiled plasmids (AG30) versus the chloroterpyridine platinum concentration, i.e., the ratio of intercalated molecules to the number of phosphate sites in DNA. A significant increase in the number of ssb and dsb was observed when the DNA contained intercalated molecules. This technique is an efficient way to induce ssb and dsb triggered by the atomic Auger effect.

Algorithms↗
PubMed2001

Large-scale selection of lines with deletions in chromosome 1 B in wheat and applications for fine deletion mapping.

Terminal deletions of chromosome 1B in common wheat were selected on a large scale. The gametocidal gene of Aegilops cylindrica was used as the inducer of chromosome breakage. First, genes for endosperm storage proteins located on both arms of chromosome 1B were used as the selection markers. However, it was found that the chromosome breakage occurred during female gametogenesis, causing genotypic inconsistency between the embryo and endosperm. Thus, we isolated plants with terminal deletions in chromosome 1B by C-banding. Of 1327 plants examined, 128 showed aberrations in chromosome 1B: 47 in the short arm, 76 in the long arm, and 5 in both arms. The present deletions tended to have the breakpoint at more proximal regions than those produced previously by T.R. Endo and B.S. Gill. Using 33 deletion lines produced in this study and 34 lines previously produced, we mapped 39 RFLP loci and a nucleolar organizer region (NOR) on a specific region of chromosome 1B. The NOR was found to consist of two subregions with different repetitive units, which were termed NOR-Bld and NOR-Blp. Based on this fine deletion map and genotypic inconsistency between embryo and endosperm, the features of the gametocidal gene are discussed.

Chromosome Aberrations↗
PubMed2000

Kinetic alteration of a human dihydrodiol/3alpha-hydroxysteroid dehydrogenase isoenzyme, AKR1C4, by replacement of histidine-216 with tyrosine or phenylalanine.

Human dihydrodiol dehydrogenase with 3alpha-hydroxysteroid dehydrogenase activity exists in four forms (AKR1C1-1C4) that belong to the aldo-keto reductase (AKR) family. Recent crystallographic studies on the other proteins in this family have indicated a role for a tyrosine residue (corresponding to position 216 in these isoenzymes) in stacking the nicotinamide ring of the coenzyme. This tyrosine residue is conserved in most AKR family members including AKR1C1-1C3, but is replaced with histidine in AKR1C4 and phenylalanine in some AKR members. In the present study we prepared mutant enzymes of AKR1C4 in which His-216 was replaced with tyrosine or phenylalanine. The two mutations decreased 3-fold the K(m) for NADP(+) and differently influenced the K(m) and k(cat) for substrates depending on their structures. The kinetic constants for bile acids with a 12alpha-hydroxy group were decreased 1.5-7-fold and those for the other substrates were increased 1.3-9-fold. The mutation also yielded different changes in sensitivity to competitive inhibitors such as hexoestrol analogues, 17beta-oestradiol, phenolphthalein and flufenamic acid and 3,5,3', 5'-tetraiodothyropropionic acid analogues. Furthermore, the mutation decreased the stimulatory effects of the enzyme activity by sulphobromophthalein, clofibric acid and thyroxine, which increased the K(m) for the coenzyme and substrate of the mutant enzymes more highly than those of the wild-type enzyme. These results indicate the importance of this histidine residue in creating the cavity of the substrate-binding site of AKR1C4 through the orientation of the nicotinamide ring of the coenzyme, as well as its involvement in the conformational change by binding non-essential activators.

3-Hydroxysteroid Dehydrogenases↗
PubMed2000

Roles of His-79 and Tyr-180 of D-xylose/dihydrodiol dehydrogenase in catalytic function.

Mammalian dimeric dihydrodiol dehydrogenase is identical with d-xylose dehydrogenase and belongs to a protein family with prokaryotic proteins including glucose-fructose oxidoreductase. Of the conserved residues in this family, either His-79 or Tyr-180 of d-xylose/dihydrodiol dehydrogenase has been proposed to be involved in the catalytic function. Site-directed mutagenesis was used to examine the roles of the two residues of the monkey enzyme. A mutant, Y180F, was almost inactive, but, similarly to the wild-type enzyme, exhibited high affinity for NADP(H) and fluorescence energy transfer upon binding of NADPH. The H79Q mutation had kinetically largest effects on K(d) (>7-fold increase) and K(m) (>25-fold increase) for NADP(H), and eliminated the fluorescence energy transfer. Interestingly, the dehydrogenase activity of this mutant was potently inhibited with a 190-fold increase in the K(m) for NADP(+) by high ionic strength, which activated the activity of the wild-type enzyme. These results suggest a critical role of Tyr-180 in the catalytic function of this class of enzymes, in addition to functions of His-79 in the coenzyme binding and chemical steps of the reaction.

Animals↗
PubMed2000

Strand break induction by photoabsorption in DNA-bound molecules.

Dried samples of a DNA-chloroterpyridine platinum complex were irradiated with monochromatic X rays tuned to the photoabsorption resonance of the L(III) inner shell of the platinum atom. The number of single- and double-strand breaks (SSBs and DSBs) triggered by the Auger effect in supercoiled DNA plasmids was measured by the production of circular nicked and linear forms. To probe the specific contribution of the L(III) inner-shell excitation of the platinum atom, photon wavelengths were tuned on the resonance energy (on peak) and below (off peak). The quantum yields of the resonance radiation were typically found to be 11 for the SSBs and 1 for the DSBs. The DSB-to-SSB ratio increased by 20% when switching from off-resonance to on-resonance irradiation.

DNA↗
PubMed2000

Clinical application of artificial ligament for ankle instability--long-term follow-up.

We have applied a reconstructive operation to patients with injury of the lateral ligament in the ankle joint using an artificial ligament made of polyester (Leeds-Keio) since 1985. The operation was performed on 451 feet of 436 patients. Average follow-up period was 5 years and 8 months. Talar tilt and anterior drawer translation before and after the operation were improved from 16 degrees to 4 degrees and from 11 mm to 4 mm, respectively. In this study, which has followed the same patients over an extended period, there were no cases with a decrease in the range of motion of the joint, with further development of osteoarthritis, or with a poorer result than those observed in our earlier study, which reported a short-term follow-up of the same patients. It may therefore be concluded that this reconstructive procedure of the lateral ligament of the ankle joint, using the artificial ligament, is also excellent after long-term follow-up.

Adolescent↗
PubMed2000

[Radiological evaluation of foot deformities in rheumatoid arthritis].

Deformities of the feet are common in patients with rheumatoid arthritis (RA). We investigated whether there was any correlation among forefoot deformities, flat foot or articular destruction of the midfoot and hindfoot, in 146 feet of 73 RA patients whose age varied from 26 to 81 years (mean 58.5 years). In all patients, anteroposterior (AP) and lateral radiographs of the feet with weight bearing were obtained. The hallux valgus angle (HVA), the intermetatarsal angle between the 1st and 2nd metatarsals (M 1 M 2), and the intermetatarsal angle between the 1st and 5th metatarsals (M 1 M 5) were measured on AP radiographs. On slateral radiographs, the height of the arch was measured and articular destruction of the talocalcaneal, talocrural, talonavicular, cuneonavicular and cuneometatarsal joints was measured and classified using Steinbrocker's classification. The average HVA was 23.4 degrees, the average M 1 M 2 was 11.1 degrees, and the average M 1 M 5 was 28.4 degrees. There was no correlation between forefoot deformities and flat foot. There were significant correlations between arthritic destruction of the cuneometatarsal joint and HVA, M 1 M 2 and M 1 M 5. The correlations between arthritic destruction of the cuneonavicular joint and HVA or M 1 M 2 were also significant, although weaker. Thas, we found some relationships between forefoot deformity and arthritics destruction of midfoot joints. Especially, the correlations between arthritic destruction of the cuneonavicular and cuneometatarsal joints and forefoot deformities were significant. Many radiographic methods for the assessment of RA have been reported, however, it is difficult to assess sarthritic destruction of rheumatoid feet with the existing methods. Accordingly, a new method should be established.

Adult↗
PubMed1999

De novo synthesis of telomere sequences at the healed breakpoints of wheat deletion chromosomes.

When chromosomes are broken, the breakpoints become highly unstable and acquire the ability to fuse with other broken ends. The breakpoints are, however, eventually stabilized, and, therefore, the broken chromosomes are transmitted to the daughter cells without further morphological change. This phenomenon, known as "healing of breakpoints", involves the addition of repetitive telomere sequences at the breakpoints by telomerase, the enzyme that normally synthesizes the telomere sequence at normal chromosome terminals. In many higher organisms, however, this property has not been well investigated. In this study, we examined the telomere sequences in wheat deletion lines with breakpoints on chromosome 1B. Lines that had breakpoints around the nucleolar organizer region were first selected on the basis of cytological observations, and the precise breakpoints were determined by mapping a fragment of rDNA and RFLP markers. In three lines - in addition to one previously reported - the DNA fragments encompassing the breakpoints were amplified by PCR using primers located in the rDNA and in telomere sequences. The DNA sequences provide insight into the properties of the telomerase activity at the breakpoints. The telomere sequences initiated from 2- to 4-nucleotide motifs in the original ribosomal DNA sequence which are also found in the repeat unit characteristic of telomere sequences. No specific sequences or structures were observed at or around the breakpoints. At all of the four breakpoints investigated, the newly synthesized telomere sequences contained considerable numbers of atypical telomere sequence units, particularly TTAGGG, which is the common unit of mammalian telomere sequences. Based on these results, we discuss the ability of plant telomerase to initiate the de novo synthesis of telomere sequences at internal breakpoints.

Base Sequence↗
PubMed1999

Synthesis and pharmacological evaluation in mice of halogenated cannabidiol derivatives.

Six halogenated derivatives of cannabidiol (CBD, 1) substituted on the aromatic ring at the 3' and/or 5' position, 3'-chloro- (2), 3',5'-dichloro- (3), 3'-bromo- (4), 3',5'-dibromo- (5), 3'-iodo- (6) and 3',5'-diiodo-CBD (7) were synthesized and their pharmacological effects of barbiturate-induced sleep prolongation, anticonvulsant effects and locomotor activity were evaluated by intravenous (i.v.) injection in mice. 2 (10 mg/kg, i.v., 69 +/- 10 min) significantly prolonged pentobarbital-induced sleeping time by 3.1-fold, compared to control (22 +/- 2 min), although other 1 derivatives used did not significantly affect the sleeping time. 2, 4 and 6 (10 mg/kg, i.v.) significantly prolonged hexobarbital-induced sleeping time by 2.0-, 2.0- and 2.3-fold, respectively, compared with control (52 +/- 5 min). On the other hand, 1 and all halogenated derivatives did not significantly prolong barbital-induced sleeping time. The monohalogenated derivatives, 2, 4 and 6 were able to prolong pentobarbital and hexobarbital-induced sleeping time, although the dihalogenated derivatives, 3, 5 and 7 did not exhibit a prolongation of the sleeping time. All halogenated derivatives of 1 except for brominated derivatives (2, 3, 6, 7) tended to prolong tonic seizure latency induced by pentylenetetrazol. 1 and its halogenated derivatives did not exhibit any prolongation of seizure latency induced by picrotoxin or strychnine. Maximal electroshock test demonstrated that 1 and 4 exhibited almost the same potency in their anticonvulsant effects, although other 1 derivatives 2, 3, 5, 6 and 7 did not show significant effect up to a dose of 63 mg/kg, i.v. The ED50 values (mg/kg, i.v.) of 1 and 4 were 38 and 44, respectively. 1 and 4 also showed anticonvulsant effect in minimal and maximal electroshock-threshold tests. 2, 4 and 6 tended to decrease the total distance (horizontal activity) and number of rearings (vertical activity) of mice, whereas 3, 5 and 7 tended to increase the number of rearings. However, the effects of all derivatives were not statistically significant from the control. 2 and 4 were the most potent derivatives on pharmacological activities among the synthetic cannabinoids examined in the present study. These results indicate that monohalogenation of 1 leads to some modification of the pharmacological profile of CBD.

Animals↗
PubMed1998

[Combined rupture of trachea and esophagus following blunt trauma--a case report].

A 49-year-old man was involved in a motor vehicle crash and was admitted to a local hospital. The following day, he was transferred to our hospital because of worsening dyspnea. Initial examination revealed no subcutaneous emphysema, and chest computed tomography (CT) demonstrated no mediastinal air. A left thoracentesis tube was placed for pneumothorax, which reduced the patient's respiratory distress. He had a persistent, productive cough, which worsened when he drank water. A repeat chest CT on the fifth hospital day revealed a tracheo-esophageal fistula. Bronchoscopy and esophagoscopy confirmed the diagnosis. He underwent repair of the trachea and esophagus. The ruptured membraneous portion of the trachea was closed with interrupted sutures and covered with pedicled pericardial flap. The perforated anterior esophageal wall was sutured in layers and reinforced with a fifth intercostal muscle flap. A gastrostomy tuve was placed for feeding access. Within 6 weeks, the patient recovered completely.

Esophagus↗
PubMed1998

Synthesis and pharmacological activities in mice of halogenated delta 9-tetrahydrocannabinol derivatives.

Seven halogenated derivatives of delta 9-tetrahydrocannabinol (delta 9-THC, 1) substituted on the aromatic ring at the 2 and/or 4 position, 2 (4)-fluoro- (2), 2,4-difluoro- (3), 2-chloro- (4), 2-bromo- (5), 2,4-dibromo- (6), 2-iodo- (7) and 2,4-diiodo-delta 9-THC (8) were synthesized and pharmacological effects such as catalepsy, anticonvulsant effects, hypothermia, pentobarbital-induced sleep prolongation and locomotor activity evaluated by intracerebroventricular (i.c.v., 25 micrograms/head) and intravenous (i.v., 5 or 10 mg/kg) injections in mice. The cataleptogenic effects of 2 and 5 were about three-quarters and two-thirds, respectively, compared to those of 1 (i.v.), though other derivatives were much less active (i.c.v. and i.v.). 2 (for clonic seizures) exhibited a significant prolongation of seizure latency induced by pentylenetetrazol (i.v.). Hypothermic effects of monohalogenated derivatives were comparable to 1 when administered by i.v. injection, whereas the effects of dihalogenated derivatives of 1 were attenuated. In contrast, 3 and 8 exhibited a significant hyperthermic effect in mice. In synergy with pentobarbital, 4 and 5 exhibited a significant prolongation of sleeping time by 1.6- and 1.8-fold, respectively, compared with control (32.4 +/- 2.5 min), although other derivatives did not affect significantly the sleeping time (i.c.v.). However, by i.v. injection, 2, 4, 5 and 7 significantly prolonged pentobarbital-induced sleeping time and reduced locomotor activity. The sleep prolonging effects of 2, 4 and 7 (10 mg/kg, i.v.) were as potent as that of 1 (5 mg/kg, i.v.). 5 and 7 were the most potent derivatives among the synthetic cannabinoids examined in the present study. These results indicate that halogenation of 1 leads to modification of the pharmacological profile of THC.

Animals↗
PubMed1997

Anterior subtalar dislocation: case report.

Anterior subtalar dislocations are extremely rare. To our knowledge, only four cases have been reported in detail in the literature. A diagnosis of anterior subtalar dislocation should be confirmed by an anteroposterior view radiograph because lateral subtalar dislocation always includes some anterior displacement of the mid-foot. We report a case of anterior subtalar dislocation confirmed by both lateral and anteroposterior view radiographs and discuss its pathomechanism, diagnosis, and treatment.

Adult↗
PubMed1997

Closed complete rupture of the flexor hallucis longus tendon at the groove of the talus.

A rare case of closed complete rupture of the flexor hallucis longus tendon at its groove in the posterior process of the talus is reported in a soccer player who developed pseudarthrosis of the posterolateral tubercle of the talus after a Shepherd's fracture. Partial rupture or tenosynovitis of the flexor hallucis longus tendon at this level is well known in classical ballet dancers and soccer players. Three cases of complete rupture of the flexor hallucis longus tendon near the metatarsophalangeal joint and three under the sustentaculum tali have been reported, but there have been no reports at the groove of the talus. Repair was accomplished by tendon graft, and active flexion of the interphalangeal joint is now possible.

Adult↗