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Naoki Kato

Publications and source records attributed to Naoki Kato.

34 records · Page 2Linked to original sources
PubMed2003

Screening of stress enhancer based on analysis of gene expression profiles: enhancement of hyperthermia-induced tumor necrosis by an MMP-3 inhibitor.

To improve the therapeutic benefit of hyperthermia, we examined changes of global gene expression after heat shock using DNA microarrays consisting of 12 814 clones. HeLa cells were treated for 1 h at 44 degrees C and RNA was extracted from the cells 0, 3, 6, and 12 h after heat shock. The 664 genes that were up or down-regulated after heat shock were classified into 7 clusters using fuzzy adaptive resonance theory (fuzzy ART). There were 41 genes in two clusters that were induced in the early phase after heat shock. In addition to shock response genes, such as hsp70 and hsp40, the stress response genes c-jun, c-fos and egr-1 were expressed in the early phase after heat shock. We also found that expression of matrix metalloproteinase 3 (MMP-3) was enhanced during the early response. We therefore investigated the role of MMP-3 in the heat shock response by examining HeLa cell survival after heat treatment in the presence and absence of an MMP-3 inhibitor, N-isobutyl-N-(4-methoxyphenylsulfonyl)glycylhydroxamic acid (NNGH) or N-hydroxy-2(R)-[[4- methoxysulfonyl](3-picolyl)amino]-3-methylbutaneamide hydrochloride (MMI270). The number of surviving cells 3 days after heat treatment significantly decreased, reaching 3.5% for NNGH and 0.2% for MMI270. These results indicate that the MMP-3 inhibitors enhanced heat shock-induced cell death and behaved as stress enhancers in cancer cells. This valuable conclusion was reached as a direct result of the gene expression profiling that was performed in these studies.

Cell Survival↗
PubMed2003

New insertion sequence elements in the upstream region of cfiA in imipenem-resistant Bacteroides fragilis strains.

The 747-bp cfiA gene, which encodes a metallo-beta-lactamase, and the regions flanking cfiA in six imipenem-resistant and four imipenem-susceptible Bacteroides fragilis strains isolated in Japan were analyzed by PCR and DNA sequencing. The nucleotide sequences of the cfiA genes (designated cfiA(1) to cfiA(10)) of all 10 strains tested varied from that of the standard cfiA gene from B. fragilis TAL2480. However, putative proteins encoded by the cfiA variants contained conserved amino acid residues important for zinc binding and hairpin loop formation, suggesting that cfiA variants have the capability of producing metallo-beta-lactamases with full catalytic activities. PCR assay indicated that six metallo-beta-lactamase-producing, imipenem-resistant strains had an insertion mutation in the region immediately upstream of cfiA. Nucleotide sequencing of the PCR-amplified fragments along with the upstream region of cfiA revealed that there were five new kinds of insertion sequence (IS) elements (designated IS612, IS613, IS614, IS615, and IS616, with a size range of 1,594 to 1,691 bp), of which only IS616 was found to be almost identical to IS1188, one of the IS elements previously identified in the upstream region of cfiA. These elements had target site duplications of 4 or 5 bp in length, terminal inverted repeats (14, 15, or 17 bp in size), and a large open reading frame encoding a putative transposase which is required for the transcription of IS elements. Each element was inserted such that the transcriptional direction of the transposase was opposite to that of cfiA. A computer-aided homology search revealed that, based on the homology of their putative transposases, the sizes of their terminal inverted repeat sequences, and their target site duplications, IS612, IS613, IS614, and IS615 belong to the IS4 family, which includes IS942, previously found in some drug-resistant B. fragilis strains, but that IS616 belongs to the IS1380 family. All the IS elements appear to have putative promoter motif sequences (the -7 region's TAnnTTTG motif and the -33 region's TTG or TG) in their end regions, suggesting that the IS elements provide a promoter for the transcription of cfiA upon insertion. These data provide additional proof that various IS elements may exist to provide a promoter to express the cfiA gene.

Amino Acid Sequence↗
PubMed2003

The expression of sterigmatocystin and penicillin genes in Aspergillus nidulans is controlled by veA, a gene required for sexual development.

Secondary metabolism is commonly associated with morphological development in microorganisms, including fungi. We found that veA, a gene previously shown to control the Aspergillus nidulans sexual/asexual developmental ratio in response to light, also controls secondary metabolism. Specifically, veA regulates the expression of genes implicated in the synthesis of the mycotoxin sterigmatocystin and the antibiotic penicillin. veA is necessary for the expression of the transcription factor aflR, which activates the gene cluster that leads to the production of sterigmatocystin. veA is also necessary for penicillin production. Our results indicated that although veA represses the transcription of the isopenicillin synthetase gene ipnA, it is necessary for the expression of acvA, the key gene in the first step of penicillin biosynthesis, encoding the delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase. With respect to the mechanism of veA in directing morphological development, veA has little effect on the expression of the known sexual transcription factors nsdD and steA. However, we found that veA regulates the expression of the asexual transcription factor brlA by modulating the alpha/beta transcript ratio that controls conidiation.

Aspergillus nidulans↗
PubMed2003

New types of toxin A-negative, toxin B-positive strains among Clostridium difficile isolates from Asia.

A total of 56 C. difficile strains were selected from 310 isolates obtained from different hospitals in Japan and Korea and from healthy infants from Indonesia. Strains that had been previously typed by pulsed-field gel electrophoresis and PCR ribotyping, were characterized by toxinotyping and binary toxin gene detection. When toxinotyped, 35 strains were determined to be toxinotype 0, whereas 21 strains showed variations in toxin genes and could be grouped into 11 variant toxinotypes. Six of the toxinotypes had been described before (I, III, IV, VIII, IX, and XII). In addition, five new toxinotypes were defined (XVI to XX). Three of the new toxinotypes (XVIII, XIX, and XX) vary only in repetitive regions of tcdA and produce both toxins. In two strains from toxinotypes XVI and XVII, the production of TcdA could not be detected with commercial immunological kits. Strain J9965 (toxinotype XVII) was in PaLoc similar but not identical to another known A(-)B(+) strain, C. difficile 8864. Strain SUC 36 (toxinotype XVI), on the other hand, was similar to well-defined group consisting of toxinotypes V, VI, and VII, which thus far includes only A(+)B(+) strains. Toxinotypes XVI and XVII represent two new groups of A(-)B(+) strains. Strains of the well-known A(-)B(+) group from toxinotype VIII have a nonsense mutation at the beginning of tcdA gene, and the introduction of a stop codon at amino acid position 47 results in nonproduction of TcdA. The 5'-end sequence of tcdA in two newly described A(-)B(+) strains does not contain an identical mutation. The prevalence of variant C. difficile strains varied greatly among nine hospitals. Only five strains from four different hospitals were positive in PCR for amplification of the binary toxin gene.

Amino Acid Sequence↗
PubMed2002

Treatment of the chronic inflammation in peripheral target tissue improves the crushed nerve recovery in the rat: histopathological assessment of the nerve recovery.

An experimental study was performed to investigate the influence of subsidence of chronic inflammation in peripheral target tissue on the recovery of crushed nerve. Seventy-eight male Wistar rats weighing 300-370 g were used. The sciatic nerve was operatively crushed unilaterally with an aneurysm clip (250 gf) applied for 5 min. Chronic inflammation, localized to the ankle, was induced by intra-articular injection of complete Freund's adjuvant 1 week preoperatively. Prednisolone farnesylate (PNF-21) 1.4% gel was applied on the ankle as an anti-inflammatory agent for consecutive days after the operation. The animals were divided into five groups as follows: crush injury with ipsilateral arthritis (CIA); crush injury with ipsilateral arthritis and PNF-21 gel applied on the ipsilateral ankle (CIA + IPNF); crush injury with ipsilateral arthritis and PNF-21 gel applied on the contralateral ankle (CIA + CPNF); crush injury with contralateral arthritis (CCA); crush injury without arthritis (C). Specimens for histopathological examination were taken from the nerve at a site 5 mm distal to the crush lesion at 4 weeks postoperatively. The average axon diameter was significantly larger in the CIA + IPNF group than in the CIA group (p < 0.01). No significant difference was observed between the CIA + CPNF group and the CIA group. In conclusion, chronic inflammation in peripheral target tissue suppresses recovery of the crushed nerve, and subsidence of this chronic inflammation improves this suppression histopathologically.

Animals↗
PubMed2002

Isomaltose formed by alpha-glucosidases triggers amylase induction in Aspergillus nidulans.

Among various alpha-glucobioses examined, isomaltose was the most effective inducer for amylase synthesis in Aspergillus nidulans. Amylase induction by maltose was completely inhibited by addition of castanospermine or cycloheximide, while induction by isomaltose was not affected by the inhibitors, suggesting that amylase induction by maltose requires inducible alpha-glucosidases. Disruption of the alpha-glucosidase A gene ( agdA), the alpha-glucosidase B gene ( agdB), or both genes did not abolish maltose-dependent induction, although amylase production induced by maltose decreased about 2-fold in the agdA/ agdB double disruptant, compared with that in the agdB disruptant at all concentrations tested. Upon induction by isomaltose, amylase synthesis was enhanced considerably in the agdB and agdA/ agdB disruptants. Even at 3 nM, isomaltose induced amylase production in the double disruptant, supporting the suggestion that isomaltose is a physiological inducer for amylase. Therefore, maltose must be converted to isomaltose by alpha-glucosidases prior to triggering amylase synthesis, but no specific alpha-glucosidase is required for amylase induction by maltose. Probably any alpha-glucosidases having isomaltose-forming activity, including AgdA and AgdB, may participate in amylase induction by maltose.

Aspergillus nidulans↗
PubMed2002

Molecular epidemiological study of vertical transmission of vaginal Lactobacillus species from mothers to newborn infants in Japanese, by arbitrarily primed polymerase chain reaction.

We investigated mother-to-newborn infant transmission of Lactobacillus species in Japanese by the typing of isolates from the vagina of pregnant women and stool specimens from their newborn infants. All infants were born by uncomplicated vaginal delivery and were basically fed breast milk. Lactobacillus strains were fingerprinted by arbitrarily primed polymerase chain reaction (AP-PCR), using ERIC1R and ERIC2 primers. Of 86 pregnant women tested, 71 (82.6%) were positive for vaginal lactobacilli. At 5 days after birth, 24 (33.8%) of the 71 infants whose mothers were lactobacilli-positive had fecal lactobacilli, while only 1 (6.7%) of the 15 infants delivered from the vaginal lactobacilli-negative mothers was lactobacilli-positive ( P < 0.01). Lactobacillus crispatus was the most prevalent species of vaginal lactobacilli in mothers and of fecal lactobacilli in infants at 5 days of age, whereas Lactobacillus gasseri was the most common in infants at 1 month of age. Identification to the species level, followed by AP-PCR typing, demonstrated that 23.3% of the 86 infants were likely to be colonized in the intestine by the vaginal lactobacilli of their mothers, and that only 2 of the infants retained the same vaginal lactobacilli until 1 month of age. These results suggest that approximately one-fourth of infants acquire vaginal lactobacilli from their mothers at birth, and that the acquired lactobacilli do not last in the intestine of the infant long-term, but rather, are replaced by ones from milk or unknown sources after birth. AP-PCR with primers ERIC1R and ERIC2 is indicated as a potential tool for the typing of Lactobacillus strains.

Bacterial Typing Techniques↗
PubMed2002

Posttraumatic volar tendon subluxation out of the first extensor compartment: a case report.

Symptomatic volar subluxation of the abductor pollicis longus and the extensor pollicis brevis tendons developed in a 29-year-old man after a sprain that occurred with the wrist in flexion and ulnar deviation. The extensor retinaculum, which forms the extensor compartment, was partially avulsed from its insertion on the radius. Palmar abduction and extension of the thumb with the wrist flexed produced subluxation of the tendons over the volar side of the radius ridge where the retinaculum forming the first extensor compartment attached. Nonoperative treatment including steroid injection and splinting was ineffective. Surgery was performed to reconstruct a new tendon restraint with part of the extensor retinaculum.

Accidental Falls↗
PubMed2002

Multiple neurilemmomas of the median and ulnar nerves with a communicating branch in the same upper extremity.

A 30-year-old woman presented with multiple neurilemmomas in the same upper extremity. One originated from the main trunk of the ulnar nerve and two others from the sensory branch of the median nerve. A communicating branch in the palm from the ulnar nerve to the median nerve was confirmed. All the tumours were successfully enucleated and she made a satisfactory recovery.

Adult↗
PubMed2002

Chondroid syringoma of the hand.

We describe a patient with a benign chondroid syringoma of the little finger of the right hand. She was a 56-year-old pianist who had had the swelling for 25 years without it causing any symptoms. The tumour was excised with an excellent result. Although chondroid syringoma is rare, it should be included in the differential diagnosis of the soft tumours of the hand.

Adenoma, Pleomorphic↗
PubMed2002

Ruptures of flexor tendons at the wrist as a complication of fracture of the distal radius.

We report two cases of rupture of flexor tendons after fracture of the distal radius. The first case was a rupture of the flexor digitorum profundus and superficialis tendon to the index finger that happened 20 years after the fracture. The second was a rupture of the flexor pollicis longus tendon that occurred two years after, and the flexor profundus tendon to the index finger that occurred four years after the fracture. In the first case, the ruptures were caused by the bony protuberance of the radius after long interval without interference of the ulnar head.

Aged↗
PubMed2002

Effect of resovist on rats with different severities of liver cirrhosis.

RATIONALE AND OBJECTIVES: Whether the degree of diffuse hepatic damage is correlated with the signal change on MR images after injection of superparamagnetic iron oxide (SPIO) particles was investigated. In addition, we investigated whether hepatic function deteriorates after injection of SPIO. METHODS: Seventy-six female Sprague-Dawley rats aged 3 to 4 weeks were given drinking water containing 0.03% thioacetamide (TAA) for 4 or 12 weeks to induce two grades of liver injury. Seventeen normal rats were served as a control. Normal and model rats were administered Resovist (10 micromol Fe/kg), and signal intensities in the liver on MR images obtained at 4.7 T were measured up to 60 minutes after injection (n = 5). The model rats were injected with 10 times the envisaged dose of Resovist (100 micromol Fe/kg) or saline as a control substance, and blood parameters were measured at 4, 24, and 48 hours after injection (n = 5 or 6). At 4 hours after injection, iron and Kupffer cells in the liver were stained (n = 3). RESULTS: Maximal signal reduction in the liver occurred 15 minutes after injection in all groups. The reduced signal persisted for 60 minutes after injection. However, the degree of maximal signal reduction in the model rats was significantly less than that in the normal rats (P < 0.05, 0.01). Signal reduction in the 12-week group was less than that in the 4-week group. In control rats, the number of iron-positive cells increased by 22 cells per area (0.065 mm(2)) following treatment with Resovist. In the 4-week and 12-week groups, numbers of iron-positive cells increased by 13 and 11 cells, respectively. There was no statistically significant difference in the number of Kupffer cells between control and model rats. No significant change was observed in blood parameters with Resovist. CONCLUSION: The MR signal induced by Resovist depended on the degree of phagocytic activity in the liver. The safety profiles of Resovist remained unchanged even at 10 times the imaging dose.

Animals↗
PubMed2002

Gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid interaction with clinical drugs in rats.

RATIONALE AND OBJECTIVES: To investigate whether the hepatic enhancement characteristics of Gd-EOB-DTPA are influenced by the preapplication of a variety of commonly used clinical pharmaceuticals (eg, antibiotics, antineoplastic drugs, corticosteroids, antiarrhythmia drugs, antianxiety drugs, scopolamine, and xanthine derivatives). MATERIALS AND METHODS: Eleven commercially available drugs (prednisolone, rifampicin, doxorubicin hydrochloride, cisplatin, propranolol hydrochloride, scopolamine butylbromide, theophylline, ampicillin, cefotaxime sodium, verapamil hydrochloride, and diazepam) were intravenously (IV) injected in rats at three to five times the clinical dose (n = 3 or 6 per drug). A control group of rats was given saline (n = 6). Gd-EOB-DTPA (25 micromol Gd/kg IV) was administered to rats 30 minutes after the injections of the clinical drugs. Liver MR imaging was performed with a 2.0 T animal imager before and up to 60 minutes after injection. Enhancement (ENH) (%) and area under the data from time versus enhancement curve (AUD) were calculated. RESULTS Rifampicin was the only drug that significantly decreased the hepatic enhancement by Gd-EOB-DTPA. Both the maximum enhancement of the liver and the AUD were significantly reduced when rifampicin was preinjected. Preinjection of prednisolone, doxorubicin hydrochloride, cisplatin or propranolol hydrochloride yielded a slightly but significant increased maximum enhancement of the liver. Furthermore, the enhancement declined more slowly when these drugs were preadministered, yielding a large AUD. None of the other drugs showed a significant effect on hepatic enhancement. CONCLUSION: Rifampicin exerted a clinically significant decrease on hepatic enhancement by Gd-EOB-DTPA. Prednisolone, doxorubicin hydrochloride, cisplatin, or propranolol hydrochloride slightly but significantly increased the hepatic enhancement by Gd-EOB-DTPA.

Animals↗
PubMed2002

Novel alpha-glucosidase from Aspergillus nidulans with strong transglycosylation activity.

Aspergillus nidulans possessed an alpha-glucosidase with strong transglycosylation activity. The enzyme, designated alpha-glucosidase B (AgdB), was purified and characterized. AgdB was a heterodimeric protein comprising 74- and 55-kDa subunits and catalyzed hydrolysis of maltose along with formation of isomaltose and panose. Approximately 50% of maltose was converted to isomaltose, panose, and other minor transglycosylation products by AgdB, even at low maltose concentrations. The agdB gene was cloned and sequenced. The gene comprised 3,055 bp, interrupted by three short introns, and encoded a polypeptide of 955 amino acids. The deduced amino acid sequence contained the chemically determined N-terminal and internal amino acid sequences of the 74- and 55-kDa subunits. This implies that AgdB is synthesized as a single polypeptide precursor. AgdB showed low but overall sequence homology to alpha-glucosidases of glycosyl hydrolase family 31. However, AgdB was phylogenetically distinct from any other alpha-glucosidases. We propose here that AgdB is a novel alpha-glucosidase with unusually strong transglycosylation activity.

Amino Acid Sequence↗