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Biomedical subjects

K Naruse

Publications and source records attributed to K Naruse.

At least 37 records · Page 2Linked to original sources
PubMed1997

Nitric oxide synthase I immunoreactivity in the macula densa of the kidney is angiotensin II dependent.

The present study was undertaken to clarify the mechanism of the regulation of nitric oxide synthase (NOS)-I in the macula densa of the kidney. We determined the changes in NOS-I immunoreactivity of the macula densa relevant to the changes in systemic blood pressure (BP) and the renin-angiotensin system. Rats received four different types of treatment, and kidney sections were immunohistochemically stained for renin, NOS-I, and NOS-III. Plasma renin activity (PRA) and angiotensin II (Ang II) concentration were determined by radioimmunoassay. In the low-salt group, PRA, plasma Ang II, and the number of renin and NOS-I positively stained areas in the juxtaglomerular apparatus (JGA) were all increased, while BP and NOS-III in the glomerular capillaries did not change. In the desoxycorticosterone acetate (DOCA)-salt group, in contrast to the elevation of BP, PRA, plasma Ang II, and all immunohistochemical parameters were decreased. In the Ang II infusion group, BP, plasma Ang II, and the number of NOS-I positive glomeruli were increased, while PRA and renin staining were decreased. Administration of Ang II type 1 receptor (AT-1) antagonist TCV-116 significantly increased PRA, plasma Ang II, and the number of renin-positive glomeruli. However, BP, and NOS-I and NOS-III staining did not show any difference. These results clearly suggest that NOS-I in the macula densa changes in parallel with plasma Ang II, but not renin or systemic BP.

Angiotensin II↗
PubMed1996

Nerve function and blood flow in Otsuka Long-Evans Tokushima Fatty rats with sucrose feeding: effect of an anticoagulant.

To investigate the pathogenesis of diabetic neuropathy in non-insulin-dependent diabetes mellitus, Otsuka Long-Evans Tokushima Fatty rats, an animal model of non-insulin-dependent diabetes mellitus, and non-diabetic Long-Evans Tokushima Otsuka rats were fed with or without sucrose and/or cilostazol, an anticoagulant, for 8 weeks. Sucrose-fed diabetic rats showed a delayed motor nerve conduction velocity, decreased R-R interval variability of electrocardiogram, reduced sciatic nerve blood flow, increased platelet aggregability and a decreased erythrocyte 2,3-diphosphoglycerate concentration compared with non-sucrose-fed diabetic rats and non-diabetic rats. These abnormalities were significantly prevented by treatment with cilostazol without changes in the nerve tissue levels of polyols. These findings indicate that sucrose-fed Otsuka Long-Evans Tokushima Fatty rats may be a useful animal model of neuropathy in non-insulin-dependent diabetes mellitus, and that cilostazol may prevent the development of diabetic neuropathy by modifying vascular factors.

2,3-Diphosphoglycerate↗
PubMed1996

A YAC contig of the human CC chemokine genes clustered on chromosome 17q11.2.

CC chemokines are cytokines that attract and activate leukocytes. The human genes for the CC chemokines are clustered on chromosome 17. To elucidate the genomic organization of the CC chemokine genes, we constructed a YAC contig comprising 34 clones. The contig was shown to contain all 10 CC chemokine genes reported so far, except for one gene whose nucleotide sequence is not available. The contig also contains 4 CC chemokine-like genes, which were deposited in GenBank as ESTs and are here referred to as NCC-1, NCC-2, NCC-3, and NCC-4. Within the contig, the CC chemokine genes were localized in two regions. In addition, the CC chemokine genes were more precisely mapped on chromosome 17q11.2 using a somatic cell hybrid cell DNA panel containing various portions of human chromosome 17. Interestingly, a reciprocal translocation t(Y;17) breakpoint, contained in the hybrid cell line Y1741, lay between the two chromosome 17 chemokine gene regions covered by our YAC contig. From these results, the order and the orientation of CC chemokine genes on chromosome 17 were determined as follows: centromere-neurofibromatosis 1-(MCP-3, MCP-1, NCC-1, I-309)-Y1741 breakpoint-RANTES-(LD78gamma, AT744.2, LD78beta)-(NCC-3, NCC-2, AT744.1, LD78alpha)-NCC-4-retinoic acid receptor alpha- telomere.

Animals↗
PubMed1996

In situ identification of messenger RNA of endothelial type nitric oxide synthase in rat cardiac myocytes.

The endothelial type nitric oxide synthase (NOS) termed as NOS-III has been demonstrated in various nonendothelial cells. Although NOS-III was recently found in the cardiac tissues, identification of the cells expressing NOS-III gene in the heart remains unknown. In this study, we compared the expression of NOS-III mRNA in various tissues of rats by Northern blot analysis using a homologous cDNA probe and identified the cell type by in situ hybridization histochemistry with a cRNA probe. NOS-III mRNA was found more abundantly in atria and ventricle than in other various tissues examined. NOS-III mRNA was intensely and specifically visualized in the cardiac myocytes as well as in the endothelial cells of the heart. No staining was seen with a sense cRNA probe. These results provide the first in vivo evidence for NOS-III mRNA in the cardiac myocytes and suggest its role in the regulation of cardiac functions.

Animals↗
PubMed1996

Angiotensin converting enzyme inhibitor normalizes vascular natriuretic peptide type A receptor gene expression via bradykinin-dependent mechanism in hypertensive rats.

We previously demonstrated that angiotensin converting enzyme (ACE) inhibitor normalizes the up-regulated gene expression of vascular natriuretic peptide type A (NP-A) receptor in hypertensive rats. To elucidate the mechanism, we examined the effect of angiotensin II receptor (AT1) antagonist (TCV-116) and bradykinin receptor (B2) antagonist (Hoe 140) on the NP-A receptor mRNA level in the aorta of genetically hypertensive rats (SHR-SP/Izm) using ribonuclease protection assay. The effect of ACE inhibitor on the NP-A receptor mRNA level was completely abolished by a concomitant administration of Hoe 140, while TCV-116 did not show any significant effect on the NP-A receptor mRNA level. These results suggest that bradykinin plays an important role in the regulation of the vascular NP-A receptor gene expression.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

Molecular cloning and linkage analysis of the Japanese medaka fish complement Bf/C2 gene.

Evolutionary studies of complement factor B (Bf) and C2 in lower vertebrates have revealed the presence of the Bf/C2 common ancestor-like molecule in lamprey (cyclostome) and the Bf molecule encoded by the duplicated genes closely linked to the major histocompatibility complex (MHC) in Xenopus (amphibian). To further define when Bf/C2 gene duplication occurred and when linkage between the Bf/C2 gene and the MHC was established, we amplified the Bf/C2 sequences in teleost, the Japanese medaka (Oryzias latipes), by reverse transcription - polymerase chain reaction with primers corresponding to the common amino acid sequences shared by mammalian Bf and C2. Only a single molecular species has been amplified, and the corresponding cDNA clones were isolated from the liver cDNA library. The longest insert contained 2384 nucleotides with an open reading frame of 754 residues. The deduced amino acid sequence showed 33.6% and 34.1% overall identity with the human Bf and C2 sequences, respectively, hence this clone was named medaka Bf/C2. The single-copy medaka Bf/C2 gene had exactly the same exon-intron organization as the mammalian Bf and C2 genes, and spanned about 8 kilobases. The Bf/C2 locus was mapped to the close proximity (2.9 cM) of the superoxide dismutase locus on the linkage group XX by the use of a restriction site polymorphism between two inbred strains of the medaka.

Amino Acid Sequence↗
PubMed1996

Enhancement and inhibition of mitogenic action of insulin-like growth factor I by high glucose in cultured bovine retinal pericytes.

To explore the possible relationship between insulin-like growth factor I(IGF-I) and diabetic retinopathy, we examined the effects of glucose on IGF-I stimulated thymidine incorporation into DNA and IGF-I binding in cultured bovine retinal pericytes. IGF-I significantly increased thymidine incorporation, and its effect was completely inhibited by IGF-I receptor antibody. The exposure to high glucose for 8 h significantly enhanced the IGF-I induced increase in thymidine incorporation as compared with those to normal glucose and to high osmolarity. In contrast, the incubation with high glucose for 24 h decreased thymidine incorporation in response to IGF-I. Specific binding of IGF-I to pericytes was increased by the incubation with high glucose for both 8 and 24 h. These results suggest that glucose may play an important role in the regulation of mitogenic action of IGF-I in retinal pericytes.

Animals↗
PubMed1996

Effect of acarbose on blood glucose profiles and plasma 1,5-anhydro-d-glucitol in type 2 diabetes poorly controlled by sulfonylurea therapy.

Sixteen patients with type 2 diabetes poorly controlled by glibenclamide (7.5-10.0 mg/day) were treated with acarbose (100 mg tds) for one week and the effect on the blood glucose profile, 24-hour urinary glucose excretion, plasma fructosamine, and plasma 1,5-anhydro-D-glucitol (1,5-AG) level was determined. The blood glucose profile was more stable and levels were lower during acarbose administration. In some patients, this improvement was maintained after discontinuing acarbose. The M-value, an indicator of blood glucose fluctuations, decreased significantly from 33.2 +/- 3.0 (mean +/- SEM) in the run-in period to 13.4 +/- 2.4 during acarbose therapy (P < 0.001), and rose again to 26.5 +/- 4.4 (P < 0.001) in the follow-up period. The 24-hour urinary glucose excretion and plasma fructosamine decreased similarly (P < 0.001 and P < 0.01, respectively) during and after acarbose therapy. Plasma 1,5-AG levels did not change significantly during acarbose therapy, but increased markedly afterwards (from 19.3 +/- 3.1 mumol 1(-1) to 25.0) +/- 3.1 mumol l-1, P < 0.001). Plasma 1,5-AG levels were significantly correlated with urinary glucose excretion one week earlier (r = 0.513, P < 0.006). These findings suggest that acarbose may improve glycemic control in type 2 diabetic patients poorly controlled by sulfonylurea therapy and that plasma 1,5-AG might be used as a marker of glycemic control cooperating with other markers such as fructosamine and urinary glucose determination for monitoring the short-term response to antidiabetic therapy.

Acarbose↗
PubMed1996

Surgical resection for small hepatocellular carcinoma.

BACKGROUND: Surgical resection for hepatocellular carcinoma (HCC) can be curative in selected patients, particularly in those with a solitary small HCC (s-sHCC; 2 cm or less in diameter). However, even these patients often have a risk of tumor recurrence or death from underlying liver dysfunction. Therefore it is important to determine which clinicopathologic features are related to the long-term prognosis after resection of s-sHCC. METHODS: Fifty patients with s-sHCC underwent partial hepatectomy at our department between 1977 and 1992. Six (12%) died of liver failure in hospital after operation. Eight clinicopathologic features were examined in the remaining 44 patients with regard to their long-term prognosis by use of univariate and multivariate analyses. RESULTS: The 1-, 3-, and 5-year survival rates were 90%, 75%, and 53%, respectively. The corresponding disease-free survival rates were 80%, 53%, and 30%, respectively. None of the following parameters was significantly related to survival rate or disease-free survival rate: presence of vascular invasion or capsular formation, the distance of free surgical margin (1 cm or more or not), serum alpha-fetoprotein level, positive hepatitis B surface antigen, and preoperative transarterial embolization. Complicated liver function was the only significant factor related to survival rate and disease-free survival rate. CONCLUSIONS: A good hepatic reserve is an important factor in treating patients with s-sHCC by surgical resection, even for a long-term prognosis. Liver transplantation should be considered for patients with severe cirrhosis and s-sHCC, even though a curative resection might be possible.

Adult↗
PubMed1996

Functional stability of porcine hepatocyte spheroids in various culture systems under 100% porcine and human plasma conditions.

To select an immobilization method suitable for bioartificial liver (BAL) modules utilizing porcine hepatocyte spheroids, functional activities were compared in various systems in 100% porcine and human plasma together with a synthesized medium. The spheroids, continuously suspended in rotating dishes or entrapped in collagen (CN) gel, expressed approximately two times higher ammonium detoxification abilities over conventional monolayers during 8 days of direct contact with 100% human or porcine plasma with a standardized inoculum cell number. No significant deterioration was observed in the abilities as compared with that in a synthesized medium. Although the cell number gradually decreased in rotational culture, the abilities per cells remaining on Day 10 were two times higher than in the CN-gel entrapped spheroids in all the media examined, presumably due to the diffusion limitation by the gel. Thus, in utilizing porcine hepatocyte spheroids in BAL modules, immobilization allowing direct contact of spheroids with perfused patient plasma was concluded to be possible and suitable.

Animals↗
PubMed1996

C-type natriuretic peptide as a possible local modulator of aldosterone secretion in bovine adrenal zona glomerulosa.

Although atrial and brain natriuretic peptides are well known to be involved in the regulation of cardiovascular and endocrine functions as circulating hormones, the roles of the C-type natriuretic peptide (CNP) remain unknown. We examined the effects of CNP on the secretion of aldosterone and cyclic nucleotides from bovine adrenal zona glomerulosa cells in culture. CNP produced a dose-dependent increase in the basal secretion of cGMP, with an EC50 of 3.8 x 10(-10)M. CNP significantly inhibited the ACTH-induced increase in aldosterone and cAMP in a dose-related manner, with an IC50 of 3.6 x 10(-10)M. Although ACTH itself did not increase cGMP secretion, the addition of CNP elicited a significant increase in cGMP secretion. The effects of CNP on the basal secretion of cGMP and the ACTH-induced secretion of aldosterone were significantly reversed by a nonpeptide natriuretic peptide receptor antagonist, HS-142-1. CNP immunoreactivity was localized in the zona glomerulosa by immunohistochemical staining. In addition, expression of CNP messenger RNA and natriuretic peptide B receptor messenger RNA was demonstrated by RT-PCR in the zona glomerulosa tissue and cells in culture. These findings suggest that CNP is a local factor regulating ACTH-induced aldosterone secretion through a guanylyl cyclase-cGMP pathway.

Adrenal Glands↗
PubMed1996

Vascular action of circulating and local natriuretic peptide systems is potentiated in obese/hyperglycemic and hypertensive rats.

Hypertension is commonly associated with diabetes mellitus. The aim of the present study was to explore the pathophysiological significance of the natriuretic peptide (NP) system in hypertension associated with genetically obese/hyperglycemic Wistar fatty rats. The messenger RNA (mRNA) levels of the two biologically active NP receptors, NP-A receptor [more specific for atrial natriuretic peptide (ANP)] and NP-B receptor [more specific for C-type natriuretic peptide (CNP)], and CNP mRNA levels were determined in the aorta and kidney by ribonuclease protection assay. Plasma ANP levels were determined by RIA. Both NP-A and NP-B receptor mRNA levels in the aortae of Wistar fatty rats were double those in Wistar lean rats. Plasma ANP levels and CNP mRNA levels in the aorta of Wistar fatty rats were also significantly higher than those in Wistar lean rats. In contrast, there was no significant difference in renal levels of the mRNA for both NP receptors and CNP between the two strains. Administration of a NP-A and -B receptor antagonist, HS-142-1, to Wistar fatty rats resulted in a significant increase in systolic blood pressure and a larger decrease in plasma cGMP level than that in Wistar lean rats, with no difference in the extents of decrease in urine volume and urinary sodium excretion between the two strains. These results suggest that both the ANP/NP-A system and the CNP/NP-B system in vessels are up-regulated at the level of gene expression and may, thus, play an important role in counteracting the hypertension associated with diabetes mellitus.

Animals↗
PubMed1996

Angiotensin II-dependent down-regulation of vascular natriuretic peptide type C receptor gene expression in hypertensive rats.

Biological actions of natriuretic peptide (NP) are determined by the condition of the receptor as well as that of the hormone. Although we previously demonstrated in hypertensive rats the up-regulation of NP-A receptor that mediates various biological actions of NPs, the pathophysiologic significance of NP-C receptor, another subtype thought to be related to clearance of NPs and possibly to biological actions, remains unknown. In the present study, we determined NP-C receptor messenger RNA (mRNA) level in the aortic tissue of stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) and in cultured aortic smooth muscle cells by ribonuclease protection assay. The aortic NP-C receptor mRNA level in SHR-SP/Izm was significantly lower than that in the control WKY/Izm. Oral administration of an angiotensin (Ang) II receptor (AT1) antagonist, TCV-116, but not a calcium channel blocker, manidipine, reversed the down-regulated NP-C receptor mRNA in SHR-SP/Izm to the level in WKY/Izm, whereas the latter was more potent in decreasing the blood pressure. In cultured aortic smooth muscle cells, the NP-C receptor was the predominant subtype. Ang II decreased the NP-C receptor mRNA level in a dose-dependent manner, but this effect was reversed by an AT1 antagonist, CV-11974. Neither the NP-A nor NP-B receptor mRNA level was altered by Ang II. These findings indicate that vascular NP-C receptor is down- regulated via Ang-II-mediated mechanism in SHR-SP/Izm. The phenomenon, together with the up-regulation of the NP-A receptor, may play an important role in counteracting hypertension by enhancing the action of NPs.

Angiotensin II↗
PubMed1996

A very small juxtaglomerular cell tumor preoperatively identified by magnetic resonance imaging.

We describe a 31-year-old man. Although the plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were elevated, computed tomography and rapid sequence pyelography disclosed no abnormality. However, based on the findings of the small tumor (8 x 8 mm) in the kidney visualized by magnetic resonance imaging (MRI) and excessive PRA in the right renal vein, tumor resection was performed. The positive immunohistochemical staining of renin and the visualization of renin mRNA by in situ hybridization provided evidence supporting the diagnosis of juxtaglomerular cell tumor. Blood pressure, PRA, and PAC were normalized after the surgery. The observations suggest that MRI is a powerful diagnostic procedure in small juxtaglomerular cell tumor.

Adenocarcinoma↗
PubMed1996

Effects of beraprost sodium and insulin on the electroretinogram, nerve conduction, and nerve blood flow in rats with streptozotocin-induced diabetes.

The effect of a prostacyclin analog, beraprost sodium, on the electroretinogram, motor nerve conduction velocity, and nerve blood flow was determined in rats with streptozotocin-induced diabetes and was compared with the effect of insulin. Beraprost sodium (0.01 mg x kg-1 x day-1 for 8 weeks) significantly shortened the peak latency of the electroretinogram b-wave, increased tail nerve conduction velocity, and increased sciatic nerve blood flow in diabetic rats (P < 0.0003, 0.0001, and 0.0001 vs. untreated diabetic rats, respectively). This was accompanied by a significant increase in the 6-keto-prostaglandin F1alpha content of the thoracic aorta and a marked increase in the cAMP content of the sciatic nerve. Beraprost sodium had no effect on the sorbitol and fructose contents of the sciatic nerve and retina, but insulin (8-10 U/day) significantly reduced both parameters. These findings suggest that beraprost sodium may be useful for prevention of vascular and neural dysfunction in the retina and peripheral nerve.

6-Ketoprostaglandin F1 alpha↗
PubMed1996

Effect of propionyl-L-carnitine on motor nerve conduction, autonomic cardiac function, and nerve blood flow in rats with streptozotocin-induced diabetes: comparison with an aldose reductase inhibitor.

The effects of propionyl-L-carnitine (PCAL) on caudal motor nerve conduction velocity, the coefficient of variation of the R-R interval on the electrocardiogram, and sciatic nerve blood flow were compared with those of [5-(3-thienyl)tetrazol-1-yl] acetic acid monohydrate, an aldose reductase inhibitor, in rats with streptozotocin-induced diabetes. Diabetic control rats showed significantly delayed nerve conduction (P < .05), decreased R-R variability (P < .05) and reduced sciatic nerve blood flow (P < .05). Oral administration of PCAL (0.5 g/kg/day) and [5-(3-thienyl)tetrazol-1-yl] acetic acid monohydrate (0.05% in the diet: 60 mg/kg/day) for 8 weeks significantly improved both nerve conduction (P < .05) and R-R variability (P < .05) in diabetic rats, along with the normalization of sciatic nerve blood flow. PCAL treatment increased the nerve tissue levels of carnitine and myo-inositol and reduced the serum triglyceride level in diabetic rats. Our results suggests that PCAL could have therapeutic potential for the treatment of diabetic neuropathy.

Aldehyde Reductase↗