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Biomedical subjects

T Ogihara

Publications and source records attributed to T Ogihara.

At least 541 records · Page 30Linked to original sources
PubMed1993

Association analysis of a polymorphism of the angiotensin converting enzyme gene with essential hypertension in the Japanese population.

An association study of the insertion/deletion (I/D) polymorphism located in intron 16 of the ACE gene with essential hypertension in the Japanese population was performed. The 287 bp I/D polymorphism was detected by polymerase chain reaction. Derived allele frequencies for insertion and deletion were not significantly different between 133 hypertensive and 104 normotensive subjects. A significant relationship between I/D polymorphism and plasma ACE activity was observed in the normotensive group, but not in hypertensives. These results suggest that I/D polymorphism of the gene is not implicated in Japanese hypertensive subjects, and that studies involving various ethnic groups are important.

Adult↗
PubMed1993

Clinical evaluation of plasma des-gamma-carboxy prothrombin as a marker protein of hepatocellular carcinoma in patients with tumors of various sizes.

We measured des-gamma-carboxyprothrombin (DCP) (prothrombin induced by vitamin K absence or antagonist-II, abbreviated as PIVKA-II) by a newly developed enzyme immunoassay using an anti-DCP monoclonal antibody in 665 human subjects, of which 112 were patients with hepatocellular carcinoma (HCC). PIVKA-II was elevated to more than 0.1 AU/ml in 54 of the 112 patients (48.2%) with HCC, while it was positive only in 7.1% of those with liver cirrhosis and 3.1% of those with chronic hepatitis. Three patients with elevated PIVKA-II greater than 0.1 AU/ml who had been diagnosed as having liver cirrhosis by ultrasonography and computed tomography at the start of this study developed a diffuse type of HCC three or six months later, which was detected by angiography. No obvious correlation was observed between plasma PIVKA-II concentration and serum alpha-fetoprotein (AFP) level in HCC patients. Of the 112 HCC patients, 40.2% showed an increase in AFP to above 200 ng/ml. In the remaining patients, 32.8% had a PIVKA-II concentration greater than 0.1 AU/ml. In these patients with a negative or low serum AFP concentration, PIVKA-II proved to be a valuable tumor marker for laboratory diagnosis of HCC. Among them, 59.8% tested positive for PIVKA-II and/or AFP. Thus, combination assay with PIVKA-II and AFP seems useful for increasing the accuracy of laboratory diagnosis of HCC. None of patients with a solitary tumor smaller than 2 cm had elevated PIVKA-II. In patients with larger-sized and multiple HCC, positive results of elevated PIVKA-II were more frequent than those of increased AFP.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers↗
PubMed1993

A microsatellite polymorphism in the human insulin receptor gene: a highly informative marker for linkage analysis.

To study genetic susceptibility to non-insulin dependent diabetes mellitus (NIDDM), association of insulin receptor gene, a candidate gene for NIDDM, with NIDDM was studied. A microsatellite polymorphism located in intron 2 of the human insulin receptor gene was detected by the polymerase chain reaction and used as a genetic marker. Eight different alleles were observed, indicating highly polymorphic nature of this marker. Although no association of this marker with NIDDM was observed in Japanese subjects, this marker will be useful for linkage studies of insulin receptor gene and genes located close to this gene on chromosome 19.

Alleles↗
PubMed1993

The role of activated vascular angiotensin II generation in vascular hypertrophy in one-kidney, one clip hypertensive rats.

OBJECTIVE: To investigate the role of vascular angiotensin II (Ang II) in the vascular thickening of one-kidney, one clip (1-K, 1C) hypertensive rats, which show normal plasma renin activity. METHODS: The type 1 Ang II receptor antagonist TCV-116 (1 mg/kg per day), the angiotensin converting enzyme (ACE) inhibitor delapril (20 mg/kg per day), hydralazine (20 mg/kg per day) or vehicle were administered to four groups of 1-K, 1C rats aged 6-10 weeks. Vehicle was also given to uninephrectomized rats. RESULTS: The aortae of 1-K, 1C rats contained significantly higher levels of Ang II than those of uninephrectomized rats and showed hypertrophy, but not hyperplasia of their medial smooth muscle cells. Hypertrophy was estimated by immunohistochemical staining of alpha-actin. Hyperplasia was estimated by DNA content and incorporation of 5-bromo-2'-deoxyuridine. The blood pressure of the 1-K, 1C rats was not affected by either TCV-116 or delapril, even at doses sufficient to induce depressor effects in spontaneously hypertensive rats. However, subdepressor doses of TCV-116 and delapril both significantly reduced the alpha-actin-stained area to 78 and 73%, respectively, of that in the 1-K, 1C rats, whereas a depressor dose of hydralazine did not affect the alpha-actin-stained area. The level of Ang II in the aorta, but not in plasma, was suppressed by delapril but not by hydralazine. CONCLUSIONS: These results suggest strongly that vascular Ang II plays a major role in the development of vascular hypertrophy, independently of plasma Ang II, bradykinin and ACE-independent pathways of Ang II generation, and in the regulation of blood pressure in this normoreninaemic hypertensive model.

Actins↗
PubMed1993

Discrepancy between renin mRNA and plasma renin level in angiotensin-converting enzyme inhibitor-treated rats.

1. To investigate the role of transcriptional and post-transcriptional factors in increasing renin synthesis secondary to angiotensin-converting enzyme (ACE) inhibitors, we studied the changes in levels of renal renin mRNA, plasma renin and other hormonal factors. 2. Spontaneously hypertensive rats were orally administered 10 mg/kg spirapril or vehicle daily for 3, 14 or 28 days. 3. Plasma renin activity in the spirapril-treated group was significantly elevated compared with that in the vehicle group at any time (P < 0.01). However, there was no significant change in plasma angiotensin II concentration between the two groups. The ratio of renal renin mRNA to beta-actin mRNA in the spirapril-treated group was higher than that in the control group (P < 0.01). 4. At 28 days, plasma renin activity in the spirapril-treated group was significantly elevated compared with that at 14 days (P < 0.05). However, there was no change in renin mRNA between 14 and 28 days after ACE inhibitor administration. 5. Plasma ACE activity in the treatment group was less than that in the control group at any time (P < 0.01). 6. Our study demonstrated a non-proportional change in plasma renin and renal renin mRNA levels. It is suggested that the main determinant of the rate of renin synthesis after administration of an ACE inhibitor may be post-transcriptional factors, and that unknown mechanisms may be involved in the increase in plasma renin level after long-term administration of ACE inhibitor in addition to the short feedback mechanism brought about by the decrease in angiotensin II.

Actins↗
PubMed1993

The angiotensin-converting enzyme inhibitor, perindopril, prevents cardiac hypertrophy in low-renin hypertensive rats.

1. To examine whether an angiotensin-converting enzyme (ACE) inhibitor prevents left ventricular (LV) hypertrophy even in low-renin hypertension, we studied the effect of the administration of perindopril on cardiac hypertrophy induced by partial renal ablation in hypertensive rats. 2. Rats that had undergone partial nephrectomy were randomly divided into four groups that received the following as drinking water: Group A, tap water; Group B, 1% sodium chloride (NaCl); Group C, NaCl + perindopril 3 mg/kg per day; and Group D, NaCl + perindopril 1 mg/kg per day. Plasma renin activity (PRA), angiotensin-II (AII) concentration and cardiac tissue AII were measured. 3. Supplementation of NaCl following nephrectomy increased the blood pressure and cardiac weight compared with rats that had undergone nephrectomy alone (P < 0.05). Treatment with perindopril (3 mg/kg per day) did not affect the blood pressure and plasma AII but inhibited the increase of cardiac weight (P < 0.05). Left ventricular AII was decreased in cases of reduced renal mass hypertension, but was not changed by treatment with perindopril. 4. These results demonstrate that perindopril may be able to prevent LV hypertrophy even in low-renin hypertension, which was not mediated by a reduction of blood pressure or suppression of the circulating and cardiac renin-angiotensin systems. Other mechanisms of ACE inhibitors may contribute to the cardioprotective effects.

Angiotensin II↗
PubMed1993

Role of tissue renin angiotensin system in two-kidney, one-clip hypertensive rats.

To investigate the molecular pathology of two-kidney, one-clip (2K-1C) rats, we examined the gene expressions of the renin-angiotensin system (RAS) and angiotensin II (ANG II) concentration in various tissues in the early (4 wk) and chronic (16 wk) phases of hypertension. Four weeks after clipping, the brain renin mRNA level was lower in 2K-1C rats than in control rats (P < 0.05). On the other hand, the levels of brain and renal angiotensinogen mRNA were not significantly different in the two groups. The brain and adrenal ANG II concentrations were significantly higher in 2K-1C rats than in control rats. Sixteen weeks after clipping, there was no significant difference in the brain renin mRNA levels in the two groups, and renal and brain angiotensinogen mRNA levels were normal. Moreover, the ANG II concentrations in the adrenals and brain (except the cortex) of 2K-1C rats were not significantly higher than those in control rats. These results show a differential pattern of tissue RAS gene expression in rats during the development of 2K-1C hypertension, which is regulated in a tissue-specific manner. Furthermore, the data suggest that brain ANG II may be affected by circulating ANG II, but not by the brain renin angiotensin system, and may regulate brain renin, probably by negative feedback through its own receptor.

Actins↗
PubMed1993

Role of angiotensin II in high fructose-induced left ventricular hypertrophy in rats.

Recent studies suggest the linkage of hypertension and insulin resistance. High fructose diet is known to induce hyperinsulinemia and hypertension in rats. In a previous study, however, high fructose (66%) diet failed to elevate blood pressure but increased left ventricular weight in Sprague-Dawley rats. In the present study, we investigated the precise mechanism of high fructose diet-induced changes in the cardiovascular system in rats. Intake of fructose-enriched diet for 2 weeks increased serum insulin and plasma angiotensin II levels. Urinary excretion of sodium and norepinephrine was not changed. Blood pressure measured directly through an indwelling catheter was not increased, but left ventricular weight and protein content were increased by high fructose diet. To further elucidate the role of the renin-angiotensin system, an angiotensin II type 1 receptor antagonist, TCV-116, was given orally at 1 mg/kg per day with either normal or high fructose diet. Concomitant administration of TCV-116 did not affect plasma glucose or serum insulin levels. Plasma angiotensin II was increased, but neither urinary sodium nor norepinephrine was changed by TCV-116. TCV-116 similarly decreased blood pressure in rats on normal and high fructose diets. Increase in left ventricular weight induced by high fructose diet was prevented by the concomitant administration of TCV-116. On the other hand, left ventricular weight in control rats was not changed by TCV-116. In conclusion, increased plasma angiotensin II may account for the left ventricular hypertrophy induced by high fructose diet, whereas hemodynamic change, sodium retention, and the sympathetic nervous system do not play an important role.

Angiotensin II↗
PubMed1993

Novel in vitro gene transfer method for study of local modulators in vascular smooth muscle cells.

Although many in vitro gene transfer methods already exist, such as calcium phosphate precipitation, electroporation, or cationic liposomes, these methods cause significant cell injury and cell death. The study of the biology of endogenous autocrine-paracrine vasoactive systems such as the renin-angiotensin system in vascular cells is limited by the lack of a suitable gene transfer method with high efficiency of transfection and expression that will permit cell biology studies. Recently, the Sendai virus (hemagglutinating virus of Japan, HVJ)-liposome-mediated gene transfer method has been shown to be an efficient and nontoxic method of gene transfer. In this study, we characterized the efficiency and suitability of the HVJ method for vascular biology research. Using SV40 T-antigen complementary DNA (cDNA), we initially compared the efficiency of the HVJ method and lipofection for transfection of cultured vascular smooth muscle cells (VSMCs). We observed that after 35 minutes of incubation, the HVJ method exhibited a 10-fold higher efficiency of transfection than lipofection. We used this method to study vascular angiotensin converting enzyme (ACE) expression in cultured VSMCs and cultured rat carotid arteries in vitro. The HVJ method of transfection of human ACE cDNA into VSMCs and COS cells was significantly more efficient than lipofection. Using this method, we demonstrated that transfection of ACE cDNA resulted in increased DNA synthesis, which was inhibited by the specific angiotensin II receptor antagonist DuP 753 (10(-6) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Captopril inhibits endothelin-1 secretion from endothelial cells through bradykinin.

Incubation with captopril, an angiotensin I converting enzyme inhibitor, for 24 hours at concentrations up to 10(-7) M inhibited endothelin-1 secretion by endothelial cells. This inhibition of endothelin-1 secretion was reversed by coincubation with 3 x 10(-3) M NG-nitro-L-arginine, an inhibitor of nitric oxide synthesis. Furthermore, captopril enhanced the production of nitric oxide in endothelial cells, suggesting that enhancement of nitric oxide production participates in captopril-induced inhibition of endothelin-1 secretion. Moreover, in the presence of 10(-6) M D-Arg,[Hyp3,Thi5,8,D-Phe7]-bradykinin, a bradykinin B2 receptor antagonist, captopril did not inhibit but rather stimulated endothelin-1 secretion, whereas bradykinin inhibited endothelin-1 secretion, and this inhibition by bradykinin was reversed by coincubation with NG-nitro-L-arginine. In addition, enhancement of nitric oxide production induced by either captopril or bradykinin was inhibited by D-Arg,[Hyp3,Thi5,8,D-Phe7]-bradykinin. Although 10(-6) M des-Arg9-[Leu8]-bradykinin, a bradykinin B1 receptor antagonist, did not affect nitric oxide production by bradykinin, it enhanced the inhibition of endothelin-1 secretion by bradykinin. Furthermore, 10(-7) M des-Arg9-bradykinin, a bradykinin B1 receptor agonist, stimulated endothelin-1 secretion by endothelial cells. These findings suggest that angiotensin I converting enzyme inhibitor inhibits endothelin-1 secretion by the accumulation of endogenous bradykinin in endothelial cells and that the inhibition of endothelin-1 secretion by bradykinin is mediated via B2 receptors.

Arginine↗
PubMed1993

Angiotensin blockade and the progression of renal damage in the spontaneously hypertensive rat.

The pathophysiological role of angiotensin II in the development of renal sclerosis was investigated in 5/6-nephrectomized, 12-week-old male spontaneously hypertensive rats. After 1 week of a control period, nephrectomized rats received one of the following treatments for 4 weeks: the selective nonpeptide angiotensin II type 1 receptor antagonist TCV-116 (1 mg/kg per day), the angiotensin converting enzyme inhibitor delapril (30 mg/kg per day), hydralazine (15 mg/kg per day), or vehicle. Urinary protein and albumin excretions and systolic blood pressure were determined every week. Rats with reduced renal mass treated with vehicle had a poor survival rate (30%). Although TCV-116, delapril, and hydralazine treatment significantly improved the survival rate for 4 weeks, hydralazine failed to improve proteinuria and albuminuria as well as the decline in renal function compared with delapril or TCV-116. Histological examination revealed that both TCV-116 and delapril protected glomeruli from sclerosis, whereas hydralazine did not improve histological findings (5%, 7%, and 30% of glomeruli were affected, respectively). These results indicate that angiotensin II plays a dominant role through its type 1 receptor in the pathogenesis of renal deterioration by hypertension.

Albuminuria↗
PubMed1993

Hypertensive rats produced by in vivo introduction of the human renin gene.

We established an efficient and nontoxic in vivo gene transfer method mediated by the Sendai virus (hemagglutinating virus of Japan [HVJ]), liposomes, and nuclear protein. In this study, to produce a hypertensive model rat that is dependent on human renin, the human renin gene was introduced into adult rat liver by our efficient in vivo gene transfer method using HVJ and liposomes (HVJ-liposomes). The rats treated with HVJ-liposomes containing the human renin gene showed a significant elevation of blood pressure for 6 days compared with control rats, which received injections of HVJ-liposomes without the human renin gene. On day 5 after the transfer, human active renin as well as angiotensin II were found in the plasma of rats in which the human renin gene was introduced. Moreover, the blood pressure of these rats was significantly correlated with the plasma levels of human active renin and angiotensin II. To confirm that the elevated blood pressure was due to the expression of the human renin gene, we administered a newly developed specific human renin inhibitor, FK 906. The elevated blood pressure was normalized by the intravenous administration of this drug. These data indicate that this hypertensive rat was produced by the in vivo transfer of the human renin gene into rat liver and that the expressed human renin cleaved rat substrate (angiotensinogen). This hypertensive rat produced by in vivo gene transfer should be useful in further studies on hypertension.

Angiotensin II↗
PubMed1993

Novel and effective gene transfer technique for study of vascular renin angiotensin system.

Vascular renin angiotensin system (RAS) has been reported to exist in vascular wall. However, there is no direct evidence whether the vascular RAS per se can modulate growth of vascular smooth muscle cells (VSMC), because there is no suitable method to investigate the effect of endogenously produced vasoactive substances on growth of these cells. In this study, we transferred angiotensin-converting enzyme (ACE) and/or renin cDNAs into cultured VSMC using the efficient Sendai virus (hemagglutinating virus of Japan) liposome-mediated gene transfer method, to examine their relative roles in VSMC growth in vitro. Within 35 min or 6 h, the transfection of ACE cDNA into VSMC by hemagglutinating virus of Japan method resulted in a twofold higher ACE activity than control vector, whereas a cationic liposome (Lipofectin)-mediated method failed to show any effect. This in vitro system provided us with the opportunity to investigate the influence of endogenous vascular RAS on VSMC growth. Transfection of ACE or renin cDNA resulted in increased DNA and RNA synthesis, which was inhibited with the specific angiotensin II receptor antagonist (DuP 753: 10(-6) M). Angiotensin I added to ACE-transfected VSMC increased RNA synthesis in a dose-dependent manner. Cotransfection of renin and ACE cDNAs stimulated further RNA synthesis as compared to ACE or renin cDNA alone. These results showed that transfected components of RAS can modulate VSMC growth through the endogenous production of vascular angiotensin II, and that ACE as well as renin are rate limiting in determining the VSMC RAS activity. We conclude that the hemagglutinating virus of Japan liposome-mediated gene transfer technique provides a new and useful tool for study of endogenous vascular modulators such as vascular RAS.

Animals↗
PubMed1993

Primary embryonal carcinoma of the retroperitoneum.

A 32-year-old man with primary embryonal carcinoma of the retroperitoneum, a very rare condition, is reported. The disease took an acute course with rapid enlargement of cervical and inguinal lymph nodes, and high serum alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) values were observed. His testes were, however, intact. Remarkable tumor regression was achieved by systemic combination chemotherapy with cisplatin, vinblastine, and bleomycin (PVB therapy). This chemotherapy is beneficial even in advanced cases. In the two years since therapy, no recurrence has been observed.

Adult↗
PubMed1993

Esophageal squamous cell papilloma, suspected of squamous cell carcinoma.

A 46-year-old male without any subjective complaints was diagnosed by radiography as having one polypoid lesion at the distal esophagus. Endoscopy indicated a semipedunculated polyp about 1 cm in size, the specimens of which included atypical cells with a high N/C ratio in the submucosa. Squamous cell carcinoma of the esophagus was suspected. Cytological studies of PAS, CEA and keratin staining to atypical cells were all negative, with Lugol solution staining of the tumor. After polypectomy the lesion was diagnosed as a squamous cell papilloma of the esophagus; and the atypical cells were determined to be immature fibroblasts and/or endothelium.

Carcinoma, Squamous Cell↗