Biomedical subjects

H Kamiya

Publications and source records attributed to H Kamiya.

At least 37 records · Page 2Linked to original sources

PubMed2002

Schistosoma mansoni: kinetics of glomerulonephritis in Mongolian gerbils and its correlation with intensity and duration of infection.

The frequent occurrence of glomerular lesions in schistosomiasis patients has been reported, although appropriate animal models for the study of schistosomal glomerulonephritis have not been developed. To analyze the relationship between glomerulonephritis and Schistosoma mansoni infection, gerbils, Meriones unguiculatus, were infected with different number of cercariae and sacrificed at different weeks of post infection. Fifty cercariae were the optimum dose to produce the disease, glomerulonephritis, without early death of the animal. Infected gerbils showed heterogeneous types of glomerular lesions with increased serum creatinine level. Immune complex deposition was not detected at glomeruli of infected gerbils even by means of immunuofluorescence and also by transmission electron microscopy. However, infiltration of mononuclear cells in and around some of the altered glomeruli was observed. Immunohistochemical staining, using monoclonal antibody (HUSM-M.g. 15) specific to gerbil's T-cells, revealed significant infiltration of T-cells. These findings suggest that T-cells might be involved in the development of glomerulonephritis. Gerbil could be a useful model to clarify the role of T-cells in the development of glomerulonephritis of schistosomiasis.

Animals↗

PubMed2002

Mycoplasma pneumoniae in children with pneumonia at Mbagathi District Hospital, Nairobi.

OBJECTIVE: To determine the prevalence of mycoplasma pneumoniae in nasopharyngeal aspirates of children under five years of age suffering from pneumonia. DESIGN: Cross-sectional survey. METHODS: Two primer sets targeting the genes coding for adhesion protein and 16S rRNA were used in PCR and M. pneumoniae specific antibodies were detected using commercial article agglutination kit. Microbiological investigations to isolate common acute respiratory infectious pathogens were also carried out. RESULTS: M. pneumoniae was detected in nasopharyngeal aspirates of 33.7% of the cases by PCR while serology was positive in only 4.1%. M. pneumoniae alone (single detection) was detected in 25% of the cases while 75% occurred with other acute respiratory infectious (ARI) pathogens. However, the results did not correlate with clinical outcome or the severity of pneumonia. No significant aetiology was found in 28% of the cases investigated, however microbiological investigations by culture revealed the presence of other aetiological agents as follows: Streptococcus pneumoniae (26%), Klebsiella pneumoniae (1%), Staphylococcus aureus (3%), E. coli (2%), parainfluenza viruses (5%), Salmonella(1%), adenovirus (4%), RSV (22%) and Candida spp(13%), Mycoplasma pneumoniae was more prevalent in children aged between six months and three years. Cases of M. pneumoniae PCR positive and S. pneumoniae exhibited similar seasonal distribution with peaks in May and September. However, there was no relationship between M. pneumoniae PCR positive and the severity of pneumonia. CONCLUSION: More investigation is required to establish the significance of atypical pathogens in respiratory infections in Kenya.

Age Distribution↗

PubMed2001

Development of oligonucleotide lateral-flow immunoassay for multi-parameter detection.

We have developed a highly sensitive and rapid oligonucleotide lateral-flow immunoassay (OLFIA), using a colloidal gold as an indicator, for the simultaneous detection of antigens and/or antibodies in specimen. This system can detect more than two types of antigens and/or antibodies in a single assay device at the same time. The device is basically composed of colloidal gold-labeled antibodies and oligonucleotide-labeled antibodies fixed in a conjugate pad, and the complementary oligonucleotide-labeled proteins are immobilized on a nitrocellulose membrane. If the target antigen is present in a specimen, the colloidal gold-labeled antibody and oligonucleotide-labeled antibody will make a complex with the antigen. Subsequently, the formed complex migrates to the place where complementary oligonucleotide is immobilized and is bound to the solid phase via the DNA-DNA interaction. As a result, more than two types of reactions can be detected on a single assay device by the combination of colloidal gold-labeled antibodies, different oligonucleotide-labeled antibodies and complementary oligonucleotide-labeled proteins immobilized at different places on a nitrocellulose membrane.

Animals↗

PubMed2001

Intracellular trafficking and transgene expression of viral and non-viral gene vectors.

The objective of this review is to summarize the critical steps in intracellular trafficking and the principal factors involved in transgene expression by a comparison of viral and non-viral gene vectors. Intracellular trafficking of viral and non-viral gene vectors are reviewed kinetically as well as from the mechanistic point of view. The peptide-dependent specific mechanism of endosomal escape by viral vectors is compared with the non-specific mechanism of non-viral vectors. Regarding the nuclear transport of DNA, a number of recently developed strategies in non-viral vectors such as the application of nuclear localization signals or cell specific transcription factors are summarized in comparison with viral nuclear gene delivery. The molecular mechanisms of transcription and the translation of delivered genes to nucleus are also summarized in view of drug delivery systems. This information is intended to serve as a basis for developing a new gene delivery system for both viral and non-viral gene vectors. Optimizing the gene delivery system by integrating this intracellular trafficking as well as transgene expression will be required in order to develop an efficient and an safe gene delivery system.

Animals↗

PubMed2001

Exhaled nitric oxide decreases during exercise-induced bronchoconstriction in children with asthma.

Nitric oxide (NO) produced in the airways can be either detrimental or protective to the host. To investigate the role of NO in the pathogenesis of exercise-induced bronchoconstriction (EIB), we measured exhaled NO (ENO) after exercise challenge in 39 asthmatic and six normal children. FEV(1) and ENO were measured before and at 0, 5, 10, and 15 min after exercise performed on a treadmill for 6 min. EIB was defined as a decrease in FEV(1) of more than 15% after the exercise. Normal children (control group) did not have EIB. Twenty-one patients with asthma had EIB (EIB group) whereas the remaining 18 patients did not (non-EIB group). The baseline ENO value was significantly higher in the asthmatic children than in the normal children, and there was a positive correlation between the maximal percent decrease in FEV(1) and the baseline ENO value (r = 0.501, p = 0.012). At the end of the exercise, ENO had decreased in all the subjects. In the non-EIB and control groups, ENO rebounded to above the baseline at 5 min after the exercise and thereafter. In contrast, ENO remained at a decreased level in the EIB group. The change in ENO did not correlate with the change in minute ventilation, and beta-agonist inhalation at the peak of EIB that accelerated the recovery of FEV(1) did not affect the depressed level of ENO, demonstrating that the reduction of ENO is not a simple consequence of increased ventilation nor airway obstruction. Among the EIB group, steroid-treated patients showed sooner recovery in ENO after the exercise than steroid-naive patients. Our study suggests that NO production in response to exercise may be impaired in patients with EIB, and that ENO represents not only airway inflammation but also a protective function of NO in EIB.

Administration, Inhalation↗

PubMed2001

Hydrolysis of oxidized nucleotides by the Escherichia coli Orf135 protein.

To examine the possibility that the Orf135 protein of Escherichia coli functions as a hydrolyzing enzyme for a damaged DNA precursor (deoxyribonucleoside 5'-triphosphate), we purified the recombinant Orf135 protein and incubated it with oxidized deoxynucleotides. Of the nucleotides tested, 2-hydroxydeoxyadenosine 5'-triphosphate, and somewhat less efficiently, 8-hydroxydeoxyguanosine 5'-triphosphate, were hydrolyzed by this protein. These damaged deoxynucleotides elicit transversion mutations in E. coli (Inoue, M., Kamiya, H., Fujikawa, K., Ootsuyama, Y., Murata-Kamiya, N., Osaki, T., Yasumoto, K., Kasai, H. (1998) J. Biol. Chem. 273, 11069-11074). These results suggest that this protein may be involved in the prevention of mutations induced by these oxidized deoxynucleotides.

DNA Damage↗

PubMed2001

Phenotypic changes of adrenomedullin receptor components, RAMP2, and CRLR mRNA expression in cultured rat vascular smooth muscle cells.

Adrenomedullin is known to inhibit cell proliferation in cultured rat vascular smooth muscle cells, through a cAMP-dependent process. The calcitonin receptor-like receptor could function as an adrenomedullin receptor when co-expressed with receptor activity-modifying protein 2. To determine whether vascular adrenomedullin receptor components, the calcitonin receptor-like receptor and the receptor activity-modifying protein 2, phenotypically change during in vitro culture conditions, we examined the expression of adrenomedullin receptor components, adrenomedullin-induced cAMP production, and the inhibition of cell proliferation in culture rat vascular smooth muscle cells during serial passages. The results demonstrated that the receptor activity-modifying protein 2 and calcitonin receptor-like receptor mRNAs increased in a passage-dependent manner in rat vascular smooth muscle cells. Furthermore, the responses of both the elevation of cAMP and the inhibition of cell proliferation became larger in vascular smooth muscle cells with an increasing number of passages. The results suggest that the increase in functional AM receptor during phenotypic change may in part contribute to the development of vascular lesions, such as in atherosclerosis.

Adrenomedullin↗

PubMed2001

Arg660Ser mutation in Thermus aquaticus DNA polymerase I suppresses T-->C transitions: implication of wobble base pair formation at the nucleotide incorporation step.

We examined the replication fidelity of an Arg660Ser (R660S) mutant of Thermus aquaticus DNA polymerase I (Taq pol I). In a forward mutation assay, R660S showed a marked reduction in T-->C transitions, one of the most frequent errors made by the wild-type enzyme. Steady-state kinetics showed that R660S discriminates against dGTP incorporation at a template T 13-fold better than the wild-type. R660S was also 3.2-fold less efficient than the wild-type at extending a T:dG mismatch. These results indicate that R660S has enhanced fidelity during incorporation and extension, which reduces its T-->C transition frequency. Interestingly, R660S also discriminated correct from incorrect nucleotides at the incorporation step of C:dATP, A:dATP, G:dATP and C:8-OH-dGTP mispairs 28-, 6.0-, 4.1- and 6.8-fold better, respectively, than the wild-type, although it may not always be as accurate as the wild-type at the extension step. A structural model suggests that Arg660 may participate in two interactions that influence fidelity; the guanidinium group of Arg660 might interact with the incoming guanine base at the major groove and it might compete for forming another interaction with the primer terminus. Substituting Arg with Ser may eliminate or alter these interactions and destabilize the closed complex with incorrect substrates. Our data also suggest that T:dGTP and C:dATP base pairs form 'wobble' structures at the incorporation step of Taq pol I.

Arginine↗

PubMed2001

Thermodynamic stability of base pairs between 2-hydroxyadenine and incoming nucleotides as a determinant of nucleotide incorporation specificity during replication.

We investigated the thermodynamic stability of double-stranded DNAs with an oxidative DNA lesion, 2-hydroxyadenine (2-OH-Ade), in two different sequence contexts (5'-GA*C-3' and 5'-TA*A-3', A* represents 2-OH-Ade). When an A*-N pair (N, any nucleotide base) was located in the center of a duplex, the thermodynamic stabilities of the duplexes were similar for all the natural bases except A (N = T, C and G). On the other hand, for the duplexes with the A*-N pair at the end, which mimic the nucleotide incorporation step, the stabilities of the duplexes were dependent on their sequence. The order of stability is T > G > C >> A in the 5'-GA*C-3' sequences and T > A > C > G in the 5'-TA*A-3' sequences. Because T/G/C and T/A are nucleotides incorporated opposite to 2-OH-Ade in the 5'-GA*C-3' and 5'-TA*A-3' sequences, respectively, these results agree with the tendency of mutagenic misincorporation of the nucleotides opposite to 2-OH-Ade in vitro. Thus, the thermodynamic stability of the A*-N base pair may be an important factor for the mutation spectra of 2-OH-Ade.

Base Pairing↗

PubMed2001

Methylglyoxal, an endogenous aldehyde, crosslinks DNA polymerase and the substrate DNA.

Methylglyoxal, a known endogenous and environmental mutagen, is a reactive alpha-ketoaldehyde that can modify both DNA and proteins. To investigate the possibility that methylglyoxal induces a crosslink between DNA and DNA polymerase, we treated a 'primed template' DNA and the exonuclease-deficient Klenow fragment (KF(exo-)) of DNA polymerase I with methylglyoxal in vitro. When the reaction mixtures were analyzed by SDS-PAGE, we found that methylglyoxal induced a DNA-KF(exo-) crosslink. The specific binding complex of KF(exo-) and 'primed template' DNA was necessary for formation of the DNA-KF(exo-) crosslink. Methylglyoxal reacted with guanine residues in the single-stranded portion of the template DNA. When 2'-deoxyguanosine was incubated with Nalpha-acetyllysine or N-acetylcysteine in the presence of methylglyoxal, a crosslinked product was formed. No other amino acid derivatives tested could generate a crosslinked product. These results suggest that methylglyoxal crosslinks a guanine residue of the substrate DNA and lysine and cysteine residues near the binding site of the DNA polymerase during DNA synthesis and that DNA replication is severely inhibited by the methylglyoxal-induced DNA-DNA polymerase crosslink.

Acetylcysteine↗

PubMed2001

Isolation, structure determination, and synthesis of neodysiherbaine A, a new excitatory amino acid from a marine sponge.

[structure: see text] A new excitatory amino acid, neodysiherbaine A (2), was isolated as a minor constituent of the aqueous extract from the marine sponge Dysidea herbacea. The structure was deduced by spectroscopic methods and established unambiguously by the total synthesis. The present synthesis, including as a key step cross-coupling of the 6/5-bicyclic core with an amino acid residue, is useful in constructing its structural analogues.

Alanine↗

PubMed2001

Relation of a common methylenetetrahydrofolate reductase mutation and plasma homocysteine with intimal hyperplasia after coronary stenting.

BACKGROUND: Hyperhomocysteinemia has been identified as an independent risk factor for coronary artery disease. Recent studies have shown that a common mutation (nucleotide 677 C-->T) in the methylenetetrahydrofolate reductase (MTHFR) gene may contribute to mild hyperhomocysteinemia and, therefore, to the incidence of coronary artery disease. No information exists, however, regarding the association between the mutation of the MTHFR gene or plasma homocysteine levels and morphological analysis of coronary atherosclerosis using intravascular ultrasound. METHODS AND RESULTS: To examine the potential influence of MTHFR genotype and homocysteine on coronaryarteries morphologically, we screened 62 patients with 65 lesions that were treated with 93 Palmaz-Schatz stents. The plasma homocysteine levels in the patients with the TT genotype were not significantly higher than those in the patients with non-TT (CC+CT) genotypes (13.1 +/- 5.5 versus 11.5 +/- 3.1 mmol/L, P=0.16). Angiographic analysis showed that the percent diameter stenosis in the patients with the TT genotype was significantly greater than that in those with non-TT genotypes (43.7 +/- 17.8% versus 29.0 +/- 22.0%, P=0.015). Intravascular ultrasound analysis showed that the TT genotype was significantly associated with greater intimal hyperplasia area (5.70 +/- 1.94 versus 3.72 +/- 1.38 mm2, P=0.001). In multiple stepwise regression analysis, the number of the T alleles was the only independent predictor of intimal hyperplasia after intervention (r2=0.21, P=0.004). CONCLUSIONS: The homozygous mutant genotype of the MTHFR gene may increase the risk of in-stent restenosis more than does the normal homozygous or heterozygous genotype.

Alleles↗

PubMed2001

Role of PKC and TGF-beta receptor in glucose-induced proliferation of smooth muscle cells.

The role of protein kinase C (PKC) and transforming growth factor (TGF)-beta in the proliferation of vascular smooth muscle cells (SMCs) under a high glucose condition was investigated. [3H]-thymidine incorporation under 20 mM glucose was significantly accelerated compared with that under 5.5 mM glucose, and this increase was inhibited by an anti-TGF-beta antibody or a PKC-beta specific inhibitor, LY333531. The amount of active and total TGF-beta1 in the conditioned media did not differ between 5.5 and 20 mM glucose. However, the expression of TGF-beta receptor type II under 20 mM glucose was significantly increased, but that of the TGF-beta receptor type I was not. This increased expression of the TGF-beta receptor type II was prevented by LY333531. These observations suggest that the increased expression of the TGF-beta receptor type II via PKC-beta plays an important role in the accelerated proliferation of SMCs under a high glucose condition, leading to the development of diabetic macroangiopathy.

Activin Receptors, Type I↗

PubMed2001

Involvement of 1,2-diacylglycerol in improvement of heart function by etomoxir in diabetic rats.

Abnormal lipid metabolism has been proposed to be involved in the pathogenesis of diabetic cardiomyopathy. In this study, we measured myocardial lipid levels, including 1,2-diacylglycerol (1,2-DAG) and ceramide (CM), and myocardial function in diabetic rats. We also evaluated the effects of etomoxir (ETM), a carnitine palmitoyl transferase I inhibitor, on diabetic rat hearts from the viewpoints of alterations in lipid second messengers and myocardial function. Rats were injected with streptozotocin (60 mg/kg) to induce diabetes and were treated 5 weeks later with ETM (18 mg/kg) for 8 days. In diabetic rats, heart rate, systolic blood pressure, and fractional shortening were significantly reduced compared with those in controls. Treatment of diabetic rats with ETM ameliorated myocardial dysfunction other than heart rate. Myocardial 1,2-DAG levels in diabetic rats were significantly elevated compared with those in controls, while myocardial CM levels were not. ETM treatment caused an additional increase in myocardial 1,2-DAG levels in diabetic rats, but the CM levels did not change. There was a marked difference in fatty acid pattern of 1,2-DAG between diabetic and ETM-treated diabetic rat hearts. The fatty acids 18:1 and 18:2 were significantly increased and the fatty acids 16:0, 18:0, 20:4, and 22:6 were significantly reduced in ETM-treated diabetic rat hearts. These data suggest 1,2-DAG is involved in ameliorating myocardial dysfunction in diabetic rats and that its source is different between diabetic and ETM-treated diabetic rats. CM is unlikely to be involved in the pathogenesis of diabetic cardiomyopathy or the improvement of cardiac contractility in diabetic rats by ETM.

Animals↗

PubMed2001

Effect of quinapril on intimal hyperplasia after coronary stenting as assessed by intravascular ultrasound.

We studied whether angiotensin-converting enzyme inhibition with quinapril treatment can prevent in-stent restenosis after successful implantation of Palmaz-Schatz stents. Intravascular ultrasound study, but not quantitative coronary angiography analysis, revealed that quinapril treatment significantly prevented the loss of both minimal lumen cross-sectional area and lumen volume in stents, in addition to reducing the increase in intimal hyperplasia volume.

Aged↗

PubMed2001

Human MTH1 protein hydrolyzes the oxidized ribonucleotide, 2-hydroxy-ATP.

The human nucleotide pool sanitization enzyme, MTH1, hydrolyzes 2-hydroxy-dATP and 8-hydroxy-dATP in addition to 8-hydroxy-dGTP. We report here that human MTH1 is highly specific for 2-hydroxy-ATP, among the cognate ribonucleoside triphosphates. The pyrophosphatase activities for 8-hydroxy-GTP, 2-hydroxy-ATP and 8-hydroxy-ATP were measured by high-performance liquid chromatography. The kinetic parameters thus obtained indicate that the catalytic efficiencies of MTH1 are in the order of 2-hydroxy-dATP > 2-hydroxy-ATP > 8-hydroxy-dGTP > 8-hydroxy-dATP >> dGTP > 8-hydroxy-GTP > 8-hydroxy-ATP. Notably, MTH1 had the highest affinity for 2-hydroxy-ATP among the known substrates. ATP is involved in energy metabolism and signal transduction, and is a precursor in RNA synthesis. We suggest that the 2-hydroxy-ATP hydrolyzing activity of MTH1 might prevent the perturbation of these ATP-related pathways by the oxidized ATP.

Adenosine Triphosphate↗

PubMed2001

Immunization of the elderly to boost immunity against varicella-zoster virus (VZV) as assessed by VZV skin test reaction.

The utility of the VZV skin test in detecting individual susceptibility to varicella and zoster was determined. Its specificity particularly with regard to herpes simplex was also established. The VZV skin test was negative or weakly positive during the early stage of herpes zoster, and strongly positive during recovery from that disease. A small-scale clinical trial to immunize elderly individuals has been performed for the purpose of preventing herpes zoster, and, perhaps, severe post-herpetic neuralgia as well. Sixty individuals > or = 50 years old were screened for VZV antibodies by IAHA test and were given a VZV skin test for cell-mediated immunity. All were seropositive, but eight were skin-test negative. Thirty-seven individuals including the eight with negative skin tests were immunized with one dose of varicella vaccine (3.0 x 10(4) PFU/dose). After 5-7 weeks, the skin test reaction showed increased positivity, with a change in score from (-) to (+, ++) in 7/8 subjects, from (+) to (++, +++) in 3/5 subjects, and from (++) to (+++) in 6/10 subjects. Enhancement of the VZV antibody titer (defined as twofold or greater) was observed in all 15 vaccine recipients with a prevaccination titer of < or = 1:16, and in 19 of 24 subjects with a prevaccination titer of > or = 1:32. These results indicate that giving live varicella vaccine with a high viral titer can induce a good boost immunity particularly cell-mediated immunity to VZV in the elderly.

Aged↗

PubMed2001

Bilateral internal thoracic artery T grafting for coronary artery revascularization. Angiographic assessment and mid-term outcome.

OBJECTIVES: We studied the early outcome of bilateral internal thoracic artery T grafting. METHODS: Coronary artery bypass grafting was studied retrospectively using bilateral internal thoracic artery T grafting in 51 patients. The T graft was made by anastomosing the free right internal thoracic artery to the in-situ left internal thoracic artery. Average patient age was 63.5 +/- 9.9 years, and the average number of anastomoses per patient was 3.6 +/- 0.9. In 35 patients, the right gastroepiploic artery (21 anastomoses in 20 patients), radial artery (1 anastomosis), free left internal thoracic artery (1 anastomosis) and saphenous vein graft (14 anastomoses in 13 patients) were used as additional bypass conduits. RESULTS: Hospital mortality was 0%. The morbidity of stroke was 1.9% (1 patient) and deep sternal infection 0%. Patency of the in-situ left internal thoracic artery was 49/50 anastomoses (98%) and that of the free right internal thoracic artery 81/84 anastomoses (96.4%). Mid-term coronary angiography in 7 patients demonstrated patent anastomosis of the T graft. Acute myocardial infarction unrelated to graft failure occurred in 2 patients during follow-up. Other patients were evaluated by exercise stress tests every year and none exhibited myocardial ischemia in the areas of T graft coronary revascularization. Three-year actuarial survival rate was 100% and freedom from cardiac events 96%. CONCLUSIONS: The bilateral internal thoracic artery T graft provides satisfactory early and mid-term outcomes in properly selected patients.

Adult↗