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Biomedical subjects

Y Komatsu

Publications and source records attributed to Y Komatsu.

At least 163 records · Page 9Linked to original sources
PubMed1998

Ten minute 13C-urea breath test for the diagnosis of Helicobacter pylori infection.

We investigated the utility of a 10-min 13C-urea breath test (13C-UBT) using 100mg of 13C-urea; this is a simple and rapid method for the detection of Helicobacter pylori infection. One hundred and fifty-one patients in whom the identification of H. pylori was established by rapid urease test, culture, and histology of six biopsy specimens underwent 254 13C-UBT examinations before and/or after eradication treatment. In the 133 patients who did not receive eradication treatment, the calculated sensitivity of the 10-min 13C-UBT was 99.4% and specificity 100% when the cut-off point was set at 3.5/1000, using a mass spectrometer. In the 121 patients who received eradication treatment, this cut-off point gave a sensitivity of 86.7%, a specificity of 99.1%, and a positive predictive value of 92.9%, with a negative predictive value of 98.1%. There were no significant differences between the diagnosis of H. pylori infection at 1 month and more than 3 months after the endpoint of eradication treatment. The 10-min 13C-UBT is suitable for the diagnosis of H. pylori infection before and after eradication treatment.

Breath Tests↗
PubMed1997

Effect of temperature on the role of Hsp104 and trehalose in barotolerance of Saccharomyces cerevisiae.

We have studied the effect of temperature on the contribution of Hsp104 and trehalose to barotolerance using mutants deficient in Hsp104 and trehalose synthesis. When compared with a corresponding wild type strain, mutants of Hsp104 did not show temperature dependent barotolerance when the incubation temperature during the hydrostatic pressure treatment was increased. However, a mutant deficient in trehalose synthesis showed features similar to a wild type strain. Furthermore, the Hsp104 level was low in the insoluble fraction of the wild type strain after pressure treatment at 35 degrees C but not at 4 degrees C, and the protein profiles in the insoluble fraction were different between 35 degrees C and 4 degrees C. In contrast to the Hsp104 deficient mutants, the protein profile of the wild type after pressure treatment at 35 degrees C favors the role of Hsp104 as a disaggregator of proteins during hydrostatic pressure stress. These results suggest that the role of Hsp104 in barotolerance is temperature dependent in contrast to trehalose.

Adaptation, Physiological↗
PubMed1997

Antigen structural requirements for recognition by a cyclobutane thymine dimer-specific monoclonal antibody.

A monoclonal antibody (TDM-2) specific to a UV-induced cyclobutane pyrimidine dimer (T[cis-syn]T) has previously been established; however,the immunization had used UV-irradiated calf-thymus DNA containing a heterogeneous mixture of photoproduct sites. We investigated here the structural requirements of antigen recognition by the antibody using chemically synthesized antigen analogs. TDM-2 bound with cis-syn,but not trans-syn thymine dimer,and could bind strongly with four nucleotide analogs in which the cis-syn pyrimidine dimer was located in the center. Antigen analogs containing abasic linkers at the 5'- or 3'-side of the cis-syn cyclobutane pyrimidine dimer were synthesized and tested for binding to TDM-2. The results indicated that TDM-2 recognizes not only the cyclobutane ring but also both the 5'- and 3'-side nucleosides of the cyclobutane dimer. Furthermore,it was proved that either the 5'- or 3'-side phosphate group at a cyclobutane dimer site was absolutely required for the affinity to TDM-2. The antibody showed a strong binding to single stranded DNA but indicated little binding to double stranded DNA.

Animals↗
PubMed1997

Reevaluating the effects of tyrosine iodination of recombinant hirudin on its thrombin inhibition kinetics.

To reevaluate the effects of iodination of hirudin on its thrombin-inhibiting activity, we iodinated a recombinant hirudin analog, CX-397, by a chloramine-T method and isolated the eight kinds of iodinated derivatives by reverse-phase HPLC. Their structure were different combinations of non-, mono-, or di-iodinated residues at Tyr-3 and Tyr-64. Their ability to inhibit alpha-thrombin were determined and compared with each other. Iodination at Tyr-64 slightly increased the association rate constant (Kon) 1.26- to 1.79-fold; this may be explained by the increase in the negative charge at C-terminal region of CX-397 caused by the electrophilic ortho substitution of Tyr-64 with iodine. On the contrary, iodination at Tyr-3 caused dual effects on the interaction between CX-397 and alpha-thrombin; namely, mono-iodination at Tyr-3 caused a small decrease in Koff (1.29- to 1.63-fold) than non-iodinated ones, whilst di-iodination at Tyr-3 brought about 3.04- to 3.88-fold increase in Koff. Since the N-terminal region of hirudin has been reported to bind with thrombin by hydrophobic interaction, the destabilizing effect of di-iodination at Tyr-3 can be explained by the increase in its polar nature, whereas the opposite effect of mono-iodination can not. These results indicate that it is not appropriate to use a mixture of variably radioiodinated hirudins as a radiotracer. We also provide a simple method to obtain well characterized radioiodinated hirudins.

Amino Acid Sequence↗
PubMed1997

A new type of hairpin ribozyme consisting of three domains.

We have constructed a new hairpin ribozyme with three stem-loop domains. In the ribozyme, another domain (domain I') was connected to the 3'-end of domain II of the parent hairpin ribozyme, and the new ribozyme can be trimmed after transcription from the DNA template using T7 RNA polymerase. Since a mutant ribozyme containing a substitution at the essential base in domain I' lacked the 3'-trimming reaction, the autoprocessing activity was proved to be derived from the catalytic reaction, similar to the wild-type ribozyme. Furthermore, the structure of the cleavage site from the self-trimming reaction was identified as a 2',3'-cyclic phosphate, which is the same as that of the wild-type. The processed ribozyme was designed to cleave an external substrate RNA derived from the mRNA of the human inducible nitric oxide synthase and was proved to cleave at the expected, unique site. The hairpin ribozyme containing the three-domains exhibited the 3'-self-trimming activity even in a runoff transcription reaction from the plasmid harboring the ribozyme gene with the three domains. The new type of hairpin ribozyme thus obtained has three stem-loop domains and is able to act as a catalytic RNA for both cis and trans cleavage. These ribozymes are of interest from the point of the structure-function relationship of the hairpin ribozyme and provide an important insight into over understanding of the role of the domain-domain interaction in the catalytic activity.

Base Sequence↗
PubMed1997

New nortriterpenoid isolated from anti-rheumatoid arthritic plant, Tripterygium wilfordii, modulates tumor growth and neovascularization.

Preparations of Tripterygium wilfordii, "Thunder God vine", have been used in China to treat rheumatoid arthritis. Rheumatoid arthritis, as well as solid tumors, is closely associated with neovascularization. Antiarthritic drugs therefore may modulate tumor growth as well as neovascularization. We found that a compound purified from T. wilfordii, the nortriterpenoid, demethylzeylasteral (TZ-93), inhibited the proliferation of vascular endothelial cells approximately 30 times more effectively than it did for the proliferation of human tumor cells. In in vitro assays using bovine aortic endothelial cells, TZ-93 at non-toxic doses inhibited cell migration, expression of urokinase-type plasminogen activator (uPA) mRNA and uPA activity. Exogenous addition of uPA restored the inhibitory effect of TZ-93 on cell migration. In dorsal air-sac assays in BALB/c mice, the oral administration of 3 mg/kg/day TZ-93 for 5 days partially inhibited, and 30 mg/kg/day almost completely abrogated, the development of capillary networks induced by human hepatoblastoma cells. Similarly, 0.3 mg/kg/day TZ-93 partially inhibited, and 3 or 30 mg/kg/day almost completely blocked, the growth of mouse B16-F10 melanoma cells in a tumor implantation assay. The highest dose of TZ-93 significantly reduced the growth of well-vascularized tumors with volumes of more than 500 mm3. TZ-93 treatment of tumor-bearing mice significantly decreased the density of microvessels in the tumors. We conclude that TZ-93 may be useful in treating highly vascularized and metastatic tumors as well as other angiogenic diseases.

Animals↗
PubMed1997

Isolation and identification of hematopoietic stem cell-stimulating substances from Kampo (Japanese herbal) medicine, Juzen-taiho-to.

We have previously found that TJ-48 has the capacity to accelerate recovery from hematopoietic injury induced by radiation and the anti-cancer drug mitomycin C (MMC). The effects are found to be due to its stimulation of spleen colony-forming unit (CFU-S) counts on day 14. In the present study, we attempt to isolate and purify the active components in TJ-48 extracts using a new in vitro hematopoietic stem cell (HSC) assay method. n-Hexane extract from TJ-48 shows a significant stimulatory activity. The extract is further fractionated by silica gel chromatography and HPLC in order to identify its active components. 1H-NMR and GC-EI-MS indicate that the active fraction is composed of free fatty acids (oleic acid and linolenic acid). When 27 kinds of free fatty acids (commercially available) are tested using the HSC proliferating assay, oleic acid, elaidic acid, and linolenic acid are found to have potent activity. The administration of oleic acid to MMC-treated mice enhances CFU-S counts on days 8 and 14 to twice the control group. These findings strongly suggest that fatty acids contained in TJ-48 actively promote the proliferation of HSCs. Although many mechanisms seem to be involved in the stimulation of HSC proliferation, we speculate that at least one of the signals is mediated by stromal cells, rather than any direct interaction with the HSCs.

Animals↗
PubMed1997

Inhibition of thymocyte apoptosis by berberine.

To find anti-apoptotic substances in plant resources, a microassay method for estimating DNA fragmentation was established using fluorochrome 3,5-diaminobenzoic acid dihydrochloride. Examination was made of various herbal medicines for inhibitory effects on glucocorticoid-induced apoptosis in thymocytes. Several Kampo medicines, e.g. Oren-gedoku-to and San'o-shashin-to, were found to inhibit dexamethasone-induced apoptosis in murine thymocytes. Some of these medicines contain Coptidis rhizoma (CR) as the major constituent, and the CR extract showed the most potent inhibitory activity on thymocyte apoptosis of more than 200 species of herbal extracts. The inhibition of apoptosis by CR extract was confirmed by the trypan blue exclusion test, lactate dehydrogenase release measurement, and morphological evaluation by electron microscopy. The benzodioxolo-benzoquinolizine alkaloid, berberine, and five berberine-type alkaloids, isolated from CR extract, had an inhibitory effect, whereas no effect was noted for the aporphin-type alkaloid magnoflorine. The inhibitory action of berberine was also demonstrated on etoposide- and camptothecin-induced apoptosis.

Animals↗
PubMed1997

Effect of byakko-ka-ninjin-to on the efferent activity of the autonomic nerve fibers innervating the sublingual gland of the rat.

The effect of intraduodenal infusion of Byakko-ka-ninjin-to (BN) on the efferent activity of the autonomic outflow to the sublingual gland was observed in the anesthetized rat. Intraduodenal infusion of BN (50-200 mg/kg) resulted in a dose-related increase in efferent activity. The enhancement of the nerve activity following administration of 200 mg/kg BN lasted longer than three hours. It was observed that the suppressive effect on efferent activity due to i.v. administration of hypertonic saline was antagonized by intraduodenal infusion of BN. From these observations it is suggested that Byakko-ka-ninjin-to acts as a facilitatory agent on salivary secretion.

Adrenergic alpha-Agonists↗
PubMed1997

Synchronous decline of serum-soluble HLA class I antigen and beta-cell function in insulin-dependent diabetes mellitus.

Serum-soluble HLA class I molecules (sHLA) have immunomodulatory functions and their serum levels correlate with the HLA class I phenotype. We studied longitudinal changes of serum sHLA levels in insulin-dependent diabetes mellitus (IDDM). A total of 198 serum samples were obtained from 40 IDDM patients before and after IDDM onset. sHLA was assayed by a sandwich ELISA. sHLA levels in IDDM patients at the initiation of insulin therapy (IDDM onset) were markedly reduced compared with those in normal controls (334.2 +/- 26.3 ng/ml vs 492.4 +/- 55.5 ng/ml, mean +/- SEM, P = 0.0038). They fell sharply during 6 months before and after the onset of IDDM. The dynamic profile of sHLA and the time course of beta-cell loss were different between IDDM patients with and without HLA-A24. In those with HLA-A24, sHLA became significantly lower than normal controls with HLA-A24 at IDDM onset. Recovery of their sHLA values occurred at 3 years from IDDM onset. On the other hand, in those without HLA-A24, sHLA levels began to decrease since the onset of IDDM and became significantly lower than normal controls without HLA-A24 at 4 years after the onset. Recovery of sHLA occurred at more than 6 years from the onset. An early (within 18 months), complete loss of beta-cell function occurred in 5 of 13 IDDM patients with HLA-A24 compared with 1 of 14 of those without HLA-A24 (P = 0.077). A late (more than 36 months after the onset of IDDM), complete loss of beta-cell function occurred in 7 of 14 IDDM patients without HLA-A24 but in none of 13 of those with HLA-A24 (P = 0.0058). These results indicate that the decline of sHLA is synchronous with massive beta-cell destruction, and that these events occur during a short period in IDDM patients with HLA-A24, whereas they occur during a relatively long period in those without HLA-A24.

Adolescent↗
PubMed1997

A role for Na/K adenosine triphosphatase in the pathogenesis of cyst formation in experimental polycystic kidney disease.

Multiple cyst formation with fluid retention is a characteristic structural abnormality in polycystic kidney disease (PKD). Na/K adenosine triphosphatase (ATPase) is a major transporting membrane protein that is ubiquitous in the epithelial cell, which has been thought to be involved in cystogenesis. We have investigated the molecular and histologic basis of Na/K ATPase activity in experimental PKD in vivo. Rats were treated with diphenylthiazole (100 mg/100 gm body weight), and cyst formation was examined histologically. Na/K ATPase activity was measured enzymatically by using a fluorometric method, and reverse transcription-competitive polymerase chain reaction (RT-PCR) analysis was used to quantitate mRNA levels in the isolated single nephron segment. Kidneys were immunostained with subunit-specific antibodies to determine the localization of Na/K ATPase in the epithelial cell. The enzyme activity increased in the cortical collecting duct from 25.9 +/- 3.5 mmol/Lpmol/mm/min to 72.9 +/- 6.8 pmol/mm/min and in the outer medullary collecting duct from 13.0 +/- 3.9 mmol/Lpmol/mm/min to 58.5 +/- 9.8 pmol/mm/min (n = 6, p < 0.01); however, all other segments showed no significant changes. No significant alternation in alpha 1- and beta 1-subunits of Na/K ATPase mRNA levels was observed by competitive PCR assay in either segment. The enzyme was stained at the basolateral membrane even in the cystic tubules. Na/K ATPase activity was up-regulated in the cyst-formed kidney, but this was not accompanied with transcriptional up-regulation. Increased Na/K ATPase activity at normal locations may play a role in abnormal net fluid transport in the development and progression of experimental PKD.

Animals↗
PubMed1997

Construction of hairpin ribozymes with a three-way junction.

Hairpin ribozymes with high cleavage activities were designed. An extra sequence was introduced at the 3'-end of the hairpin ribozyme to increase the binding to the substrate RNA, as compared to the wild-type hairpin ribozyme. A three-way junction (TWJ) was formed between the newly designed ribozyme and the substrate RNA. The complex with a solid TWJ showed less RNA cleavage activity than the wild-type hairpin ribozyme. However, the ribozyme with a TWJ with five unpaired bases or propandiol phosphate linkers had higher cleavage activity than the parent ribozyme without the TWJ. When a cis-cleavage system, in which the 5'-end of the substrate RNA was conjugated to the 3'-end of the ribozyme, was employed, the complex with the TWJ containing unpaired bases was also cleaved faster than the complex with the solid TWJ. This suggested that these differences in the cleavage activities were derived from the confirmation, and this was proven by nondenaturing gel electrophoresis. The TWJ hairpin ribozyme containing unpaired bases is able to bind strongly with substrate RNAs and to cleave them efficiently. Since the three-way ribozyme presented here is more active than the wild-type ribozyme, this type of ribozyme can serve as a more efficient tool to control RNA activities in vitro and in vivo.

Base Sequence↗
PubMed1997

Barotolerance is dependent on both trehalose and heat shock protein 104 but is essentially different from thermotolerance in Saccharomyces cerevisiae.

The contribution of trehalose and hsp104 to barotolerance in Saccharomyces cerevisiae has been investigated. Mutant strains, which lacked the ability to accumulate trehalose and/or hsp104, were examined for barotolerance and thermotolerance. All the mutants showed lower barotolerance and thermotolerance than their control strains. Trehalose had a greater protective effect towards high pressure than high temperature. Thus, trehalose and hsp104 are important factors for barotolerance and thermotolerance, but trehalose is more important for barotolerance than for thermotolerance.

Heat-Shock Proteins↗
PubMed1997

Stimulative effects of saponin from kikyo-to, a Japanese herbal medicine, on pancreatic exocrine secretion of conscious rats.

Our previous report stated that kikyo-to, a Japanese herbal medicine, consisting of the roots of Platycodon grandiflorum and Glycyrrhiza sp., stimulates the pancreatic exocrine secretion of conscious rats. The present study focused on the effective components of kikyo-to and the mechanism of stimuli to pancreatic secretion of rats. When 10 to 100 mg of platycodin D, a saponin from the root of Platycodon grandiflorum, was intragastrically administered, the pancreatic secretion of rats was stimulated. At the same time, the plasma CCK concentration increased. On the other hand, the stimulative effects of glycyrrhizin, a saponin from the root of Glycyrrhiza sp. were weak compared to platycodin D. The effects of 10 mg/kg of platycodin D on pancreatic secretion were inhibited by loxiglumide (50 mg/kg, i.g.), a CCK receptor antagonist. In contrast, the suppressive effect of atropine (300 micrograms/kg/h, i.v.) on pancreatic secretion was reduced by administering 10 mg/kg of platycodin D. In addition, up to 1 mM of platycodin D did not inhibit the trypsin activities in vitro. In conclusion, kikyo-to serves to stimulate pancreatic exocrine secretion mainly because platycodin D causes gastrointestinal hormones, particularly, CCK to be released from the duodenum.

Animals↗
PubMed1997

The effects of hange-shashin-to on gastric function in comparison with sho-saiko-to.

The effects of "Hange-shashin-to (TJ-14)" on gastric function were examined in comparison with "Sho-saiko-to (TJ-9)". Oral treatment with TJ-14 (125-500 mg/kg) caused dose-dependent suppression of ethanol-induced gastric injury, while it did not suppress gastric lesions induced by water-immersion stress. TJ-9 (125-500 mg/kg, p.o.) suppressed both water-immersion stress-induced gastric lesions and ethanol-induced gastric injury in a dose-dependent manner. Intraduodenal administration of TJ-14 even at 500 mg/kg did not affect gastric juice secretion, while TJ-9 at 125 to 500 mg/kg dose-dependently suppressed gastric juice secretion. TJ-14 (125-500 mg/kg, p.o.) accelerated gastric emptying in normal rats and improved the delayed gastric emptying induced by BaCl2 in a dose-dependent manner, whereas such effect was not noted with TJ-9. Oral treatment with TJ-14 at 500 mg/kg significantly suppressed apomorphine-induced vomiting, but it did not affect copper sulfate-induced vomiting. These results suggest that TJ-14 exhibits an anti-ulcer action (probably based on its ability to protect the gastric mucosa), improvement of gastric emptying and an anti-emetic action. TJ-9 also showed anti-ulcer effects, probably based on its ability to suppress gastric secretion and to protect the gastric mucosa. Thus, the present study demonstrated the effectiveness of TJ-14 and TJ-9 against gastric disease, and provided basic data which explain the differences in clinical application between these two kampo medicines.

Animals↗