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Biomedical subjects

K Komatsu

Publications and source records attributed to K Komatsu.

At least 73 records · Page 4Linked to original sources
PubMed2001

The use of an osseointegrated implant for orthodontic anchorage to a Class II Div 1 malocclusion.

This case report describes the use of an osseointegrated implant to maximize anchorage in a 24-year-old female orthodontic patient with an Angle Class II, Division 1 malocclusion. Preadjusted edgewise appliance therapy was performed by extraction of only the maxillary first premolars. The osseointegrated implant was placed in the median-sagittal region of the hard palate for maximum orthodontic anchorage and connected to maxillary first molar bands via a transpalatal arch. Total treatment time was 2 years and 8 months. Cephalometric superimposition revealed the achievement of maximum molar anchorage in the maxilla, resulting in satisfactory occlusal and facial improvements. Histological analysis of the implant-bone interface demonstrated that the fixture was successfully osseointegrated. In conclusion, the osseointegrated implant placed in the median-sagittal palate was shown to be an effective orthodontic system that can be used clinically as a rigid intraoral anchorage.

Adult↗
PubMed2001

Tonic excitatory input to the rostral ventrolateral medulla in Dahl salt-sensitive rats.

The goal of the present study was to test the hypothesis that the balance of tonic excitation and inhibition of vasomotor neurons in the rostral ventrolateral medulla (RVLM) driven by excitatory amino acid (EAA)-mediated inputs to the RVLM is shifted toward excitation in Dahl salt-sensitive (DS) rats compared with Dahl salt-resistant (DR) rats. Glutamate and the EAA antagonist kynurenic acid were microinjected into the RVLM of chloralose-anesthetized DS and DR rats maintained on diets containing either 0.3% NaCl or 8.0% NaCl. DS rats had a higher arterial pressure than DR rats, and this difference was greatly exaggerated by high dietary salt intake. Bilateral injection of kynurenic acid (2.7 nmol) into the RVLM decreased mean arterial pressure by 16+/-2 mm Hg in DS rats fed a diet containing 0.3% NaCl, and this effect was significantly larger in DS rats fed the high-salt diet (40+/-2 mm Hg). In contrast, injections of kynurenic acid into the RVLM did not significantly decrease arterial pressure in DR rats fed either diet. In DR rats, the pressor response elicited by the injection of glutamate into the RVLM was potentiated in rats fed the high-salt diet. The glutamate-evoked pressor response was greater in DS rats compared with DR rats, and the response in DS rats was not influenced by the salt content of the diet. These data suggest that tonically active EAA inputs to the RVLM may contribute to salt-sensitive hypertension in the Dahl model.

Animals↗
PubMed2001

Tonic excitatory input to the rostral ventrolateral medulla in Dahl salt-sensitive rats.

The goal of the present study was to test the hypothesis that the balance of tonic excitation and inhibition of vasomotor neurons in the rostral ventrolateral medulla (RVLM) driven by excitatory amino acid (EAA)-mediated inputs to the RVLM is shifted toward excitation in Dahl salt-sensitive (DS) rats compared with Dahl salt-resistant (DR) rats. Glutamate and the EAA antagonist kynurenic acid were microinjected into the RVLM of chloralose-anesthetized DS and DR rats maintained on diets containing either 0.3% NaCl or 8.0% NaCl. DS rats had a higher arterial pressure than DR rats, and this difference was greatly exaggerated by high dietary salt intake. Bilateral injection of kynurenic acid (2.7 nmol) into the RVLM decreased mean arterial pressure by 16+/-2 mm Hg in DS rats fed a diet containing 0.3% NaCl, and this effect was significantly larger in DS rats fed the high-salt diet (40+/-2 mm Hg). In contrast, injections of kynurenic acid into the RVLM did not significantly decrease arterial pressure in DR rats fed either diet. In DR rats, the pressor response elicited by the injection of glutamate into the RVLM was potentiated in rats fed the high-salt diet. The glutamate-evoked pressor response was greater in DS rats compared with DR rats, and the response in DS rats was not influenced by the salt content of the diet. These data suggest that tonically active EAA inputs to the RVLM may contribute to salt-sensitive hypertension in the Dahl model.

Analysis of Variance↗
PubMed2001

Inhibition of biliary excretion of methotrexate by probenecid in rats: quantitative prediction of interaction from in vitro data.

This study was designed to establish a strategy to predict drug interactions involving biliary excretion. The interaction between methotrexate and probenecid was examined as an interaction model since this interaction has already been clinically reported. Coadministration of probenecid reduced the biliary clearance of methotrexate in a dose-dependent manner in rats. This inhibition by probenecid was confirmed in vivo both in the uptake and excretion processes of methotrexate across sinusoidal and canalicular membranes, respectively. That is, both hepatic uptake clearance, assessed in integration plot analysis, and steady-state biliary clearance defined with respect to hepatic unbound methotrexate, were reduced in the presence of probenecid. Probenecid inhibited the active transport of methotrexate both in isolated hepatocytes and canalicular membrane vesicles, confirming the interaction at those two membranes. The degree of inhibition of the uptake and excretion processes found in vivo was comparable with the predicted values using the inhibition constant assessed in isolated hepatocytes and canalicular membranes, respectively. This suggests that the interaction at each membrane transport process can be quantitatively estimated from in vitro data. We have also proposed the method to predict the degree of inhibition of the net excretion from circulating plasma into the bile, the predicted values being also comparable with the inhibition actually found in vivo. The present analysis demonstrates a strategic rationale for predicting drug interactions involving biliary excretion using in vitro systems to avoid any false negative predictions.

Animals↗
PubMed2001

Expression of neural plasticity related gene in the pontine tegmental area of rats with overactive bladder after cerebral infarction.

PURPOSE: We investigated the expression of the neural plasticity related genes c-fos, zif268, c-jun, brain-derived neurotrophic factor and tissue plasminogen activator in the pontine tegmental area in rats with overactive bladder induced by cerebral infarction. MATERIALS AND METHODS: Cerebral infarction was induced by left middle cerebral artery occlusion in female Sprague-Dawley rats. Bladder activity was monitored by continuous infusion cystometrography in awake rats. Specimens were obtained from the pontine tegmental area 1, 3, 5, 12 and 24 hours after cerebral infarction or sham operation. The effect of 0.1 mg./kg. intravenously of the N-methyl-d-aspartate glutamatergic receptor antagonist MK-801 on bladder activity, and c-fos and zif268 expression after middle cerebral artery occlusion were studied. Real-time reverse transcriptase-polymerase chain reaction was performed with the LightCycler system (Roche Diagnostics, Mannheim, Germany) to evaluate cerebral infarction influences on gene expression in the pontine tegmental area. RESULTS: Bladder capacity in cerebral infarcted rats was significantly reduced 1 to 24 hours after middle cerebral artery occlusion compared with that of sham operated rats (p <0.05 to 0.01). One hour after occlusion mean c-fos messenger (m)RNA expression plus or minus standard error had significantly increased to 18.9 +/- 4.0 in terms of its density relative to the outer control in a sample obtained immediately after occlusion compared with that in sham operated rats (p <0.05). It returned to the control level within 3 hours after occlusion. Mean zif268 mRNA expression significantly increased to a relative density of 3.2 +/- 1.4 3 hours after middle cerebral artery occlusion (p <0.01) and returned to the control level within 5 hours after occlusion. The expressions of c-jun, brain-derived neurotrophic factor and tissue plasminogen activator was not influenced by occlusion. Pretreatment with MK-801 inhibited bladder overactivity and significantly reduced the expression of c-fos and zif268 mRNA in the pontine tegmental area. CONCLUSIONS: These results indicate that the development of bladder overactivity after middle cerebral artery occlusion is mediated by activation of an N-methyl-d-aspartate receptor and accompanied by an increase in c-fos and zif268 mRNA expression in the pontine tegmental area.

Animals↗
PubMed2001

[Long-term results of Rygg's monocusp ventricular outflow patch for the reconstruction of right ventricular outflow tract in tetralogy of Fallot].

Thirty surviving patients after corrective surgery for tetralogy of Fallot with right ventricular outflow tract reconstruction (RVOTR) using monocusp ventricular outflow patch (MVOP) were reviewed retrospectively to determine the long-term results. The age at operation ranged from 2 to 55 years with a mean of 19 years, and follow-up extended to 18.2 years (cumulative: 345.4 patient-year). There were 4 late deaths (1.2% per patient-year), and the cumulative survival rate was 85.3% at 18 years after the corrective surgery. Eight patients (2.3% per patient-year) required intracardiac reoperations mostly resulted from problems after RVOTR with MVOP, such as recurrent stenosis of right ventricular outflow tract (3 cases) or pulmonary valvular incompetence (4 cases). In addition, one patient underwent balloon angioplasty for the recurrent stenosis located in the distal end of MVOP. Freedom from surgical or catheter reintervention for the MVOP-related complication was 60.6% at 18 years after the corrective surgery. MVOP caused compression of the pulmonary artery at the distal end of the anastomosis and reoperation in a younger patients quite early after the corrective surgery. Like other transannular patches, tissue failure and degeneration of MVOP were inevitable, and resulted in severe pulmonary valvular incompetence that required the valve replacement in 4 patients (1.3% per patient-year). Freedom from pulmonary valve replacement was 71.2% at 18 years after the corrective surgery. As long-term results, our experiences emphasize the need for an innovative transannular patch that possesses significantly better long-term durability.

Adolescent↗
PubMed2001

[Effective use of electrolized soft acid aqueous solution for treatment of mediastinitis following cardiac surgery].

Mediastinitis following cardiac surgery occurs infrequently, but features both high mortality and morbidity, especially in patients with an artificial graft. A 24-year-old man was admitted with a diagnosis of Williams'syndrome with supraaortic stenosis. After ascending aorta and hemiarch reconstruction, mediastinitis developed, which was treated successfully with mediastinal irrigation using electrolized soft acid aqueous solution at one liter per day for 3 days. This procedure appears to be an effective method for treatment of mediastinitis following cardiac surgery.

Adult↗
PubMed2001

[Identification of notoginseng(Panax notoginseng) and its adulterants using DNA sequencing].

OBJECTIVE: To analyze the nuclear ribosomal RNA small subunit (18S rRNA) and chloroplast matK gene sequence of notoginseng (Panax notoginseng) in order to provide molecular evidence for its genuine origin identification. METHODS: To sequence 18S rRNA and matK genes of Panax notoginseng and its four adulterants such as P. japonicus, Curcuma phaeocaulis, C. wenyujin, C. kwangsiensis using PCR direct sequencing and to detect their variation of sequences. RESULTS: The sequence length of notoginseng and its adulterants is 1809-1811 bp for 18S rRNA gene and 1259-1548 bp for matK gene, respectively. Multiple sequence alignment shows that there are much sequence variation between notoginseng and its adulterants. CONCLUSION: DNA sequencing is an accurate and reliable method in origin identification of the genuine notoginseng.

Amino Acid Sequence↗
PubMed2001

Reduced expression of focal adhesion kinase in liver metastases compared with matched primary human colorectal adenocarcinomas.

The focal adhesion kinase (FAK) is implicated in integrin-mediated signal transduction pathways used in cell adhesion, cell motility, apoptosis, and anchorage-independent growth. Because cancer invasion and metastasis are thought to be associated with alterations in cellular adhesive and motile properties, we studied the expression of four focal adhesion proteins including FAK in matched samples of human normal colorectal mucosa (N), primary colorectal adenocarcinomas (T) and liver metastases (M) from 10 patients by Western blot analysis. This gave us the advantage of directly comparing levels of focal adhesion protein expression within the same genetic background. Average FAK expression level was significantly higher in T than in N and it was significantly lower in M than in T. Average paxillin expression level was also significantly higher in T than in N, but it was not significantly different between T and M. Similar results were obtained by immunohistochemical analyses of FAK and paxillin expression. Average vinculin and talin expression levels showed no significant differences among these three samples (N, T, and M). These data demonstrate that the FAK expression level increases in primary tumors compared with normal mucosa and decreases in liver metastases to the level of normal mucosa in the majority of human colorectal adenocarcinomas. Up- and down-regulation of FAK protein expression observed in this study may have a profound effect on the signal transduction.

Adenocarcinoma↗
PubMed2001

[A case of plasmacytoma involving adrenal gland].

We report a case of extramedullary plasmacytoma involving the right adrenal gland. A 52-year-old male was introduced under diagnosis of right adrenal tumor which was found incidentally by computerized tomography in a health check up. Laboratory data showed the presence of M protein and elevation of monoclonal lambda type IgG. It was a hormonally non-active tumor involving the adrenal area. Extramedullary plasmacytoma was confirmed by histological analysis of the resected specimen after laparoscopic right adrenalectomy. Extramedullary plasmacytoma is an uncommon neoplasm and occurs most frequently in the upper respiratory tract and is fairly rare in the adrenal area.

Adrenal Gland Neoplasms↗
PubMed2001

[A case of carbamazepine intoxication with alpha coma and status epilepticus].

We report a 14-year-old girl with carbamazepine intoxication who developed alpha coma and status epilepticus. She fell into deep coma and developed frequent generalized convulsions. The EEG during coma showed diffuse alpha activity predominantly in the frontal area. Serum carbamazepine concentration was 42.8 micrograms/ml. The convulsions were suppressed by diazepam only transiently, and by midazolam completely. Although half a day had passed since carbamazepine ingestion, we could wash out much of drug remnants by gastric lavage. Thereafter, the serum concentration of carbamazepine decreased efficiently and the patient recovered dramatically without complication. Early diagnosis and appropriate treatments should improve the prognosis of carbamazepine intoxication.

Adolescent↗
PubMed2000

PCNA interacts with hHus1/hRad9 in response to DNA damage and replication inhibition.

The hHus1 and several hRad proteins are involved in the control of DNA integrity checkpoints, although the mechanisms underlying these processes are unknown. Using a yeast two-hybrid system to detect protein-protein interactions, we found that human proliferating cell nuclear antigen (PCNA), a protein known to function in both DNA replication and repair, interacts with the human checkpoint-related protein Hus1 (hHus1). In human skin fibroblast cells, exposure to ionizing radiation of hydroxyurea triggers translocation of hHus1 from the cytosol to the nucleus, where it associates with PCNA as well as another checkpoint protein, hRad9. This nuclear translocation and the complex formation or hHus1 with PCNA and hRad9 correlate closely with changes in cell cycle distribution in response to radiation exposure. These results suggest that this multi-protein complex may be important for coordinating cell-cycle progression, DNA replication and repair of damaged DNA.

Active Transport, Cell Nucleus↗
PubMed2000

Japanese family with an autosomal dominant chromosome instability syndrome: a new neurodegenerative disease?

We report on a Japanese family having an autosomal dominant neurodegenerative disease with chromosomal instability and radiosensitivity. Clinical manifestations of affected members included short stature, osteoporosis, severe dental caries, and various neurological abnormalities, such as mental retardation, depression, dysarthria, hyperreflexia, and ataxic gait. MRI demonstrated a markedly atrophic spinal cord and degeneration of the white matter. Cytogenetic examination showed spontaneous chromosome rearrangements at 14q11.2 and hypersensitivity to radiation and bleomycin. The degree of these cytogenetic abnormalities was significantly higher in the patients than in normal controls but lower than in patients with ataxia telangiectasia or Nijmegen breakage syndrome. Moreover, genetic anticipation was observed in this family: the age of disease onset became earlier, MRI abnormalities more extensive, and the chromosome hypersensitivity to radiation increased in successive generations. We speculate that a basic defect in this family is a mutation in the gene that is responsible for DNA double-strand breakage repair.

Adult↗
PubMed2000

Anti-tumor-promoting activity of lignans from the aerial part of Saussurea medusa.

In the course of our continuing search for novel cancer chemopreventive agents from natural sources, several kinds of Compositae plants were screened. Consequently, the lignans, arctiin (ARC) and arctigenin (ARC-G), were obtained from the aerial part of Saussurea medusaas active constituents. These compounds exhibited the remarkable anti-tumor-promoting effect on two-stage carcinogenesis test of mouse skin tumors induced by 7, 12-dimethylbenz[a]anthracene as an initiator and 12-O-tetradecanoyl phorbol-13-acetate as a promoter by both topical application and oral administration. Furthermore, ARC-G exhibited potent anti-tumor-promoting activity on two-stage carcinogenesis test of mouse pulmonary tumors induced by 4-nitroquinoline-N-oxide as an initiator and glycerol as a promoter.

4-Nitroquinoline-1-oxide↗
PubMed2000

Isolation of a cDNA representing the Fanconi anemia complementation group E gene.

Fanconi anemia (FA) is an autosomal recessive chromosomal instability syndrome with at least seven different complementation groups. Four FA genes (FANCA, FANCC, FANCF, and FANCG) have been identified, and two other FA genes (FANCD and FANCE) have been mapped. Here we report the identification, by complementation cloning, of the gene mutated in FA complementation group E (FANCE). FANCE has 10 exons and encodes a novel 536-amino acid protein with two potential nuclear localization signals.

Alternative Splicing↗
PubMed2000

Schizosaccharomyces pombe Rad9 contains a BH3-like region and interacts with the anti-apoptotic protein Bcl-2.

Here we report that the Schizosaccharomyces pombe Rad9 (SpRad9) protein contains a group of amino acids with similarity to the Bcl-2 homology 3 death domain, which is required for SpRad9 interaction with human Bcl-2 and apoptosis induction in human cells. Overexpression of Bcl-2 in S. pombe inhibits cell growth independently of rad9, but enhances resistance of rad9-null cells to methyl methanesulfonate, ultraviolet and ionizing radiation. These observations suggest that SpRad9 may represent the first member of the Bcl-2 protein family identified in yeast, though the cell death pathways in S. pombe may differ from those found in mammals.

Apoptosis↗