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Mikio Kato

Publications and source records attributed to Mikio Kato.

15 recordsLinked to original sources
PubMed2006

Isolation of sperm vesicles from adult male mayflies and other insects to prepare high molecular weight genomic DNA samples.

We describe here a simple and efficient protocol for genomic DNA isolation from adult males of insects: e.g., Ephemeroptera, Odonata, Orthoptera and Dictyoptera. To minimize contamination of external DNA source, the sperm vesicles were isolated from male individuals from which high molecular weight genomic DNA was extracted. According to this protocol, the genomic DNA samples obtained were high quality (intact), and abundant enough for genotyping analyses and molecular cloning. The protocol reported here enables us to process a huge number of individuals at a time with escaping from cross-contamination, and thus it is quite useful for conducting genetic studies at least in some species of insects. The large yield of high molecular weight DNA from single individual may be advantageous for non PCR-based experiments. As a case study of the protocol, partial coding sequences of histone H3 and EF-1alpha genes are determined for some insects with PCR-amplified DNA fragments.

Aging↗
PubMed2006

DNA secondary structure forming at minisatellite repeat unit sequences.

The lengths of simple repeat sequences are generally unstable or polymorphic; that is, they are highly variable with respect to the numbers of tandem repeats. To determine the structural features that cause such variability, we examined a minisatellite DNA isolated from the yellow fin sea bream Acanthopagrus latus. Electrophoresis, CD spectra, and calorimetric analyses of oligodeoxyribonucleotides comprised of the minisatellite repeat unit suggest a stable secondary structure is formed within the repeat unit.

Animals↗
PubMed2006

Mode of evolution of the satellite DNA from the bluegill sunfish Lepomis macrochirus.

Examination of the sequence of a satellite DNA (BG16) isolated from the bluegill sunfish Lepomis macrochirus revealed that the repeat unit contains regions comprised of internal subrepeats. This suggests that the BG16 satellite evolved from a shorter repeat unit into a larger composite repeat, and a stepwise expansion model of the evolution of the BG16 satellite is proposed.

Animals↗
PubMed2006

Severity of hyperlipidemia does not affect antiatherosclerotic effect of an angiotensin II receptor antagonist in apolipoprotein E-deficient mice.

The purpose of this study was to clarify whether severity of hyperlipidemia affects the antiatherosclerotic effect of angiotensin II receptor blockers (ARBs). The effect of olmesartan medoxomil, an ARB, on atherosclerotic lesion was examined in apolipoprotein E-deficient (ApoEKO) mice fed a normal diet (ND) or a high-fat-supplemented diet (FD) for 25 weeks. ApoEKO mice have high plasma cholesterol levels, which were further increased by feeding of an FD. Both the atherosclerotic lesion area of the aortic luminal surface and the atherosclerotic lesion thickness in the aortic valves were significantly greater in the FD mice than in the ND mice. Olmesartan medoxomil did not affect the plasma cholesterol levels in either the ND or FD ApoEKO mice; however, it reduced effectively both the atherosclerotic lesion surface area and the lesion thickness even in FD ApoEKO mice. It is concluded that the antiatherosclerotic effect of ARBs is not weakened by the high plasma cholesterol level, suggesting the usefulness of ARBs in the treatment of atherosclerosis, even in a situation in which the plasma cholesterol level is not fully controlled.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2006

The effect of angiotensin II receptor blockade on an end-stage renal failure model of type 2 diabetes.

The effect of olmesartan medoxomil (OLM), an angiotensin II receptor blocker (ARB), on advanced nephropathy and mortality was evaluated in Zucker Diabetic Fatty (ZDF) rats, a type 2 diabetes model. OLM was administered from 36 weeks of age, when the animals developed advanced proteinuria. OLM effectively suppressed the progression of proteinuria. The ZDF rats started to die at 50 weeks of age, which was accompanied by abrupt increase in blood urea nitrogen, suggesting that the cause of death was renal insufficiency. OLM suppressed increases in blood urea nitrogen and increased the survival rate of the ZDF rats. The histological examination revealed that the renal damage was ameliorated by OLM. The macrophage infiltration and monocyte chemoattractant protein-1 (MCP-1) expression was increased in the glomeruli and tubulointerstitium of the ZDF rat kidneys, and the increase was lessened by OLM. In a separate study, albumin increased MCP-1 release from cultured tubular epithelial cells. These results suggest that protein leakage from the glomeruli stimulates MCP-1 production in tubular cells and that MCP-1 released into the interstitial space induces macrophage infiltration and inflammation. It is conceivable that the beneficial actions of ARB on diabetic nephropathy are, at least in part, due to decrease of proteinuria and the subsequent reduction of inflammatory changes in tubular cells.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2005

Isolation and characterization of simple repeat sequences from the yellow fin sea bream Acanthopagrus latus (Sparidae).

We isolated DNA fragments containing various repetitive elements from the genome of a sea bream Acanthopagrus latus. Sequence analysis indicated that two fragments have particularly interesting features. Fragment AL87 contained a tetranucleotide repeat and a quasipalindromic sequence. Sequence comparison suggested that AL87 may be a part of a gene encoding a serine/threonine protein kinase, and that the quasipalindrome is situated at the junction of an intron and an exon. Moreover, the quasipalindrome is conserved in several other fishes, even though it has the potential to form a stem-loop structure at the splicing site. Fragment AL79 contained a minisatellite sequence made up of six 30-bp units in tandem. DNase I sensitivity assays and statistical analyses showed the repeat region to be flexible when subjected to bending stress. In addition, atomic force microscopic imaging of AL79 showed the presence of highly curved (kinked) segments flanking the repeat region. The structural features of these repetitive elements may be key factors facilitating the amplification of the repeats.

Animals↗
PubMed2005

Effect of combined treatment with an angiotensin II receptor antagonist and an HMG-CoA reductase inhibitor on atherosclerosis in genetically hyperlipidemic rabbits.

The purpose of this study was to examine whether coadministration of olmesartan medoxomil (OLM), an AT1 subtype specific angiotensin II receptor blocker (ARB), and pravastatin (PRV), a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, could enhance the antiatherogenic effect compared with monotherapy. Vehicle, PRV (25 mg/kg), OLM (0.5 mg/kg), and PRV (25 mg/kg) and OLM (0.5 mg/kg) in combination were administered to Watanabe heritable hyperlipidemic (WHHL) rabbits for 8 months. OLM alone and in combination lowered blood pressure to a similar degree, whereas PRV alone had no effect. PRV alone and in combination lowered blood cholesterol to a similar degree, whereas OLM alone had no effect. The combination of PRV and OLM decreased effectively both surface lesion area and lesional thickness in aortic tissue, producing a greater reduction in aortic cholesterol content than either drug alone. Immunohistological examination of the aorta revealed that PRV reduced macrophage infiltration and lipid deposition and that OLM reduced macrophage infiltration accompanied by reduction in monocyte chemoattractant protein-1 expression and N-(carboxymethyl)lysine protein adduct, an oxidative stress marker. It is concluded that OLM, an ARB, and PRV, an HMG-CoA reductase inhibitor, in combination produce a greater antiatherogenic effect than monotherapy via the combination of the different antiatherosclerotic mechanisms of each drug.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2003

Evaluation of intra- and interspecific divergence of satellite DNA sequences by nucleotide frequency calculation and pairwise sequence comparison.

Satellite DNA sequences are known to be highly variable and to have been subjected to concerted evolution that homogenizes member sequences within species. We have analyzed the mode of evolution of satellite DNA sequences in four fishes from the genus Diplodus by calculating the nucleotide frequency of the sequence array and the phylogenetic distances between member sequences. Calculation of nucleotide frequency and pairwise sequence comparison enabled us to characterize the divergence among member sequences in this satellite DNA family. The results suggest that the evolutionary rate of satellite DNA in D. bellottii is about two-fold greater than the average of the other three fishes, and that the sequence homogenization event occurred in D. puntazzo more recently than in the others. The procedures described here are effective to characterize mode of evolution of satellite DNA.

Journal Article↗
PubMed2003

Interarm interaction of DNA cruciform forming at a short inverted repeat sequence.

A novel interarm interaction of DNA cruciform forming at inverted repeat sequence was characterized using an S1 nuclease digestion, permanganate oxidation, and microscopic imaging. An inverted repeat consisting of 17 bp complementary sequences was isolated from the bluegill sunfish Lepomis macrochirus (Perciformes) and subcloned into the pUC19 plasmid, after which the supercoiled recombinant plasmid was subjected to enzymatic and chemical modification. In high salt conditions (200 mM NaCl, or 100-200 mM KCl), S1 nuclease cut supercoiled DNA at the center of palindromic symmetry, suggesting the formation of DNA cruciform. On the other hand, S1 nuclease in the presence of 150 mM NaCl or less cleaved mainly the 3'-half of the repeat, thereby forming an unusual structure in which the 3'-half of the inverted repeat, but not the 5'-half, was retained as an unpaired strand. Permanganate oxidation profiles also supported the presence of single-stranded part in the 3'-half of the inverted repeat in addition to the center of the symmetry. Both electron microscopy and atomic force microscopy have detected a thick protrusion on the supercoiled DNA harboring the inverted repeat. We hypothesize that the cruciform hairpins at conditions favoring triplex formation adopt a parallel side-by-side orientation of the arms allowing the interaction between them supposedly stabilized by hydrogen bonding of base triads.

Animals↗
PubMed2002

Structural heterogeneity of pyrimidine/purine-biased DNA sequence analyzed by atomic force microscopy.

We report here the direct evidence for the formation of alternative DNA structures in a plasmid DNA, termed pTIR10, containing a 0.23-kb pyrimidine/purine-biased (Pyr/Pur) stretch isolated from the rat genome. Long Pyr/Pur sequences are abundant in eukaryotic genomes, and they may modulate the biological activity of genes and genomes via formation of various types of triplex-related structures. The plasmid DNA in sodium acetate buffer (pH 4.35) was deposited on APS-modified mica, and after drying it was imaged with an atomic force microscope in air. Various types of thick protrusions have been observed on pTIR10 DNA. Structural parameters (width and height) of DNA molecules suggest that the alternative structures observed here are variations on the theme of an intramolecular triplex. The biological relevance of the structural features within Pyr/Pur stretches is discussed.

DNA↗
PubMed2002

Renoprotective effects of blockade of angiotensin II AT1 receptors in an animal model of type 2 diabetes.

To evaluate the efficacy of angiotensin II receptor blockers (ARBs) for use in the treatment of diabetic nephropathy, we examined the effects of olmesartan medoxomil (olmesartan), an angiotensin II type 1 (AT1) specific ARB, on the progression of nephropathy in Zucker diabetic fatty (ZDF) rats, an animal model of type 2 diabetes. We used 2 doses of olmesartan, a sub-antihypertensive dose and an antihypertensive dose, to specifically examine whether the drug exerts beneficial effects on the kidney without lowering blood pressure. Olmesartan mixed in the diet at a concentration of 0.001% (approximately 0.6 mg/kg/day) or 0.01% (approximately 6 mg/kg/day) was administered for 19 weeks starting from 12 weeks of age, when the animals developed microalbuminuria. Lean non-diabetic rats served as controls. ZDF rats had hyperglycemia, hyperinsulinemia, and moderate hypertension as compared to lean control rats. Plasma glucose and insulin concentrations were not affected by olmesartan, and blood pressure was lowered only by the high dose of olmesartan. Progressive proteinuria in ZDF rats was greatly (about 70%) suppressed by the high dose of olmesartan and moderately (about 30%) suppressed by the low dose that did not significantly lower blood pressure. ZDF rats exhibited hyperlipidemia and hypoalbuminemia, both of which were substantially corrected by treatment with olmesartan. The histological evidence of glomerular and tubular damage in the ZDF rats was also reduced by the drug. These results indicate that AT1 receptor blockade with olmesartan retards the progression of nephropathy associated with type 2 diabetes without affecting glucose metabolism, and that this renal protective effect is at least partly independent of the antihypertensive effect of the drug.

Angiotensin Receptor Antagonists↗
PubMedDate not supplied

Multi-cytokine therapy for advanced renal cell carcinoma: determination of the minimal effective dose.

A low-dose cytokine combination therapy was given continuously for as extended period to seven patients with advanced renal cell carcinoma to investigate adverse reactions and anti-cancer effectiveness. These cases were: five patients with metastasis; one whose surgical removal of metastatic foci resulted in a non-curative operation; and one patient administered our regimen as postoperative treatment for locally-advanced cancer. Our regimen was started with a subcutaneous injection of a two-drug combination: 6x10(6) units interferon-alfa (IFN-alpha) and 1x10(6) units interferon-gamma (IFN-gamma) to per week iwall our patients; subcutaneous injection of 1.4x10(6) units interleukin-2 (IL-2) per week was added for three patients who showed insufficient therapeutic effects. The combination therapy was performed for 31 months maximum. Objective adverse reactions were very slight in all patients, thus they could be treated as outpatients. Therapeutic outcomes of IFN-alpha and IFN-gamma combination therapy were assessed as CR in one, PR in one, NC in 2 and PID in one patient. One patient showed NC for 27 months. Three patients, one PR case, one NC case and one PD case, were shifted to the three-drug combination therapy and the results after shifting were assessed as 2 PR cases and one PD case. These 2 PR cases are still under treatment with a good quality of life after 31 and 24 months, respectively. These results suggest the possibility of prolonging survival-time by combining continuous low-dose cytokine with conventional local treatments.

Aged↗
PubMedDate not supplied

Clinical effects of tumor-associated macrophages and dendritic cells on renal cell carcinoma.

Several reports have documented infiltration of many monocytes in renal cell carcinoma (RCC). Since few studies have examined the relationship between monocyte infiltration and clinical prognosis in RCC, we clinically investigated this relationship by semi-quantitative analysis of monocyte infiltration and tumor angiogenesis. The following six parameters were measured immunohistologically in 98 RCC patients who underwent nephrectomy between 1987 and 1997: tumor-associated macrophage (TAM), microvessel density (MVD), S-100 protein-positive cells (S-100(+) cells), HLA-DR-positive cells, apoptosis index and proliferative index (PI). We then assessed intercorrelations among parameters and correlations to prognosis. Significant positive correlations were identified for TAM, MVD and PI, with a tendency for higher parameter values to reflect poorer prognosis. The prognosis of patients without metastasis was poor for the high TAM group even when levels of MVD were low. These findings suggest that TAM facilitates the growth of RCC via angiogenesis and other mechanisms. Prognosis was significantly better in metastatic RCC patients who underwent interferon-alpha (IFN-alpha) therapy when the levels of S-100(+) cells were high. Nonetheless, the levels of S-100(+) cells among these IFN-treated patients did not correlate with other parameters, and none of the other parameters correlated with prognosis. One of the antitumor effects of IFN-alpha for RCC could therefore be mediated by dendritic cells.

Apoptosis↗