Biomedical subjects

S Oh-ishi

Publications and source records attributed to S Oh-ishi.

At least 55 records · Page 3Linked to original sources

PubMed1995

Increased growth of brown adipose tissue but its reduced thermogenic activity in creatine-depleted rats fed beta-guanidinopropionic acid.

To study the responses of thermogenic activity in brown adipose tissue (BAT) to creatine depletion, male Wistar rats were fed creatine analogue beta-guanidinopropionic acid (beta-GPA) for about 10 weeks. Compared to control rats, a marked decrease in the levels of high-energy phosphates, such as phosphocreatine and ATP, was noted in BAT of beta-GPA rats. Conversely, upward trends in other chemical components (DNA, glycogen, and total protein) in BAT as well as an increase in BAT mass were observed in beta-GPA rats, suggesting a tendency to hyperplasia of the BAT. The thermogenic activity (which was assessed by guanosine 5'-diphosphate binding to BAT mitochondria) in the mitochondria recovered from BAT of beta-GPA rats, however, was not increased in response to such changes but rather decreased. Moreover, uncoupling protein (UCP) content in the mitochondrial fraction of beta-GPA rats was significantly lower than that in control rats (the relative amounts were 77 +/- 6 and 100 +/- 4%, respectively). Nevertheless, surprisingly, the level of UCP mRNA was remarkably greater in beta-GPA rats than in control rats. These observations indicate that there is a discordance between BAT growth and activity in beta-GPA rats, thereby suggesting that a failure on and after UCP translation may be involved in the impairment of BAT thermogenic activity with creatine depletion. The impairment of BAT thermogenic activity, that is, UCP activity may indicate that uncoupling or heat production was inhibited in order to increase the ATP synthesis in BAT of beta-GPA rats in compensation for a reduction in the levels of high-energy phosphates (including ATP), with resultant hypothermia.

Adipose Tissue, Brown↗

PubMed1995

A hypotensive response induced by des-Arg9-bradykinin in young brown/Norway rats pretreated with endotoxin.

A hypotensive effect of intravenously injected des-Arg9-bradykinin was found in Brown/Norway strain young male rats which were pretreated with a small amount of endotoxin 24 h before the experiment, whereas the hypotensive effect of bradykinin was unaffected by the endotoxin. The potency of des-Arg9-bradykinin for the hypotensive effect was comparable to that of bradykinin. On the other hand, in endotoxin-pretreated aged rats, this effect of des-Arg9-bradykinin was not observed. Only during the intravenous infusion of des-Arg9[Leu8]bradykinin, a bradykinin B1 receptor antagonist, was the hypotensive effect of des-Arg9-bradykinin inhibited, whereas that of bradykinin was potentiated. After the end of infusion of des-Arg9[Leu8]bradykinin, the response to des-Arg9-bradykinin rapidly recovered. The results suggest the possibility that des-Arg9-bradykinin might play a role in inflammatory diseases.

Amino Acid Sequence↗

PubMed1995

Diquat increases cysteine proteinase inhibitors greatly in rat plasma and tissues.

Biochemical and gross pathological effects of diquat were studied with special attention to cysteine proteinase inhibitor level which was often increased in acute and chronic disorder. Diquat was fed continuously to rats at the dose of 1000 ppm in the diet. After 10 days, anorexia and severe diarrhea were observed but epistaxis and hypokinesia were not apparent. The rats were killed after feeding the diet for 13.5 days and plasma components such as acute phase reactant proteins and some vitamins which act as antioxidants were examined. The results showed that alpha-cysteine proteinase inhibitor (alpha-CPI) increased to 9-fold and vitamin C radical increased to 1.6-fold, whereas alpha 1 proteinase inhibitor (alpha 1-PI) decreased to 0.9-fold and vitamins C and E were the same as the control. Among three components of alpha-CPI, the T kininogen level in intoxicated rat plasma was about 20-fold, whereas the high molecular weight kininogen level was about 2-fold of the control. Diquat also enhanced the cysteine proteinase inhibitor (CPI) level to 20-fold in kidney and to 7- to 10-fold in the other organs. The large increment of T kininogen in these organs was also confirmed immunologically. The kidney showed a granular degeneration and its weight increased to 1.2-fold of control. The other organs showed neither gross pathological alteration nor weight change, compared with the control. The diquat distribution was highest in spleen and next highest in kidney among several organs. These results were compared with those caused by paraquat.

Animals↗

PubMed1995

Identification of rat urinary kinin as bradykinin.

Bradykinin (BK)-like activity, which was detected by BK-enzyme-immunoassay, was purified from 80 ml of ureter urine of Sprague-Dawley rats by Sephadex G 25 chromatography, FPLC, and reversed phase HPLC. The purified kinin fraction showed the same retention time as authentic BK on HPLC and produced contraction of isolated rat uterus, the contraction being suppressed by a B2-antagonist Hoe140. There was no other kinin detected on the HPLC at the corresponding retention time to kallidin, arginyl-BK or T-kinin. The peptide showed an amino acid sequence identical to that of BK by amino acid sequence analysis.

Amino Acid Sequence↗

PubMed1995

Contribution of bradykinin to heat-induced substance P release in the hind instep of rats.

To investigate the possible contribution of the bradykinin (BK) system to heat-induced substance P (SP) release from the peripheral endings of primary afferent nerves, we used the high molecular weight (HMW) and low molecular weight (LMW) kininogen-deficient rat strain (Brown Norway-Katholiek, B/N-Ka) and the normal rat strain (Brown Norway-Kitasato, B/N-Ki). We found that immersion of the paw of B/N-Ki rats in water of 47 degrees C for 20 min led to significant increases of BK, SP and Evans blue extravasation in the s.c. perfusate, and that similar treatment resulted in significantly lower levels in B/N-Ka rats. Local application of BK (10(-4) M) to the s.c. perfusate and intra-arterial infusion of BK 10(-5) mol/kg) increased Evans blue extravasation and SP release evoked by heat stimulation, respectively, in B/N-Ka rats to similar levels to those in B/N-Ki rats after heat-stimulation without BK treatment. These results indicate that BK released into the extravascular space by noxious stimulation is involved in SP release from the peripheral endings of capsaicin-sensitive primary sensory neurons.

Animals↗

PubMed1995

Acute-phase reactant proteins and antioxidants in rats intoxicated chronically with paraquat.

Paraquat dichloride at 250 ppm in the diet was fed continuously to rats. Though no apparent effect of paraquat was observed until 10 d, some rats then began to show several symptoms such as diarrhea, anorexia, epistaxis, and hypokinesia, and in some cases rats died after this period. The biochemical examination of plasma components revealed appreciable changes in the concentrations of an acute-phase reactant protein and some vitamins that act as antioxidants. alpha-Cysteine proteinase inhibitor increased by 5-fold, and vitamin C and its radical increased by 1.5- and 1.7-fold, respectively, whereas alpha 1 proteinase inhibitor decreased slightly. Paraquat enhanced the cysteine proteinase inhibitor levels in lung, liver, and kidney by 6.2-, 6.0-, and 4.5-fold of control, respectively. Among three components of alpha-cysteine proteinase inhibitor, the T kininogen level of treated rat plasma was about eight-fold higher than control, whereas the high-molecular-weight kininogen level was unchanged. The large increment of T kininogen was also seen in lungs of the treated rats.

Acute-Phase Proteins↗

PubMed1995

Activation of phospholipase A2 and acylation of lysophospholipids: the major regulators for platelet activating factor production in rat neutrophils.

Rat inflammatory neutrophils induced arachidonic acid release and platelet-activating factor (PAF) production in response to opsonized zymosan (OPZ) dose-dependently. Phospholipase A2 activity also increased dose-dependently, paralleling the increases in arachidonic acid and PAF. The time courses of the activities of phospholipase A2 and acetyltransferase, and the amounts of free arachidonic acid, lyso-PAF, and PAF demonstrated that activation of the enzymes in the remodeling pathway could be required for PAF production in rat neutrophils, which agrees with the documented fact for macrophages. Phospholipase A2 could be a rate-limiting enzyme for PAF production, since an increased lyso-PAF amount or addition of exogenous lyso-PAF reflected the increase in PAF formation in the cells. This phospholipase A2 activity in rat neutrophils could be attributed to cytosolic type phospholipase A2, because the activity was mostly suppressed by a specific antibody to cytosolic phospholipase A2. As previously reported, pretreatment of neutrophils with the acyl-CoA synthetase inhibitor, triacsin C, or the acyltransferase inhibitor, merthiolate, enhanced PAF production as well as arachidonic acid release by the cells in response to OPZ. Triacsin C inhibited arachidonoyl-CoA production and merthiolate suppressed the transacylation of lyso-PAF to 1-alkyl-2-arachidonoyl-GPC. These results suggest that these inhibitors of acylation of lyso-PAF caused accumulation of lyso-PAF, which resulted in enhancement of PAF production when phospholipase A2 and acetyltransferase were activated by OPZ. Thus the activation of cytosolic phospholipase A2 and the acylation of lyso-PAF by such as arachidonic acid could be regulating factors for PAF production in stimulated rat neutrophils.

Acylation↗

PubMed1995

Comparative study of endotoxin-induced hypotension in kininogen-deficient rats with that in normal rats.

1. The aim of this study was to clarify the role of endogenous bradykinin (BK) in the hypotensive response induced by lipopolysaccharide (LPS) by comparing the degree of hypotension caused by LPS in a strain of specific pathogen-free (SPF) Brown Norway (B/N), kininogen-deficient mutant Katholiek rats with that of B/N normal Kitasato rats. 2. The dose-dependent hypotensive responses caused by intravenous injection of BK (1-100 nmol kg-1) or platelet-activating factor (PAF, 0.003-1 microgram kg-1), were not different in the two strains of rats used. However, there was a strong difference in the hypotensive response induced by LPS in kininogen-deficient and normal rats; in normal rats the hypotensive response was composed of two phases (15 min and 70-80 min after LPS injection), but in kininogen-deficient rats LPS caused a delayed (second phase), but not an acute (first phase) hypotension. 3. We demonstrate that Hoe 140 (1 mg kg-1, i.v.) is a potent, selective, and long-lasting antagonist of the hypotensive effects of BK. Hoe 140 diminished the hypotension caused by LPS in normal rats to the level observed in kininogen-deficient rats, but had no effect on the hypotension caused by LPS in kininogen-deficient rats. 4. TCV309 (0.1 mg kg-1, i.v.) selectively inhibited the hypotension caused by repetitive injection of PAF for up to 180 min. Pretreatment with TCV309 caused a near complete inhibition of the LPS-induced hypotension in kininogen-deficient and normal B/N rats. 5. In the normal rats, dexamethasone (0.5 mg kg-1, i.p.) inhibited the second phase of the hypotension induced by LPS, but not the first phase of the hypotension. 6. A small amount of BK (0.1 nmol kg-1) potentiated the hypotensive action of PAF (0.01 microg kg-1),when they were injected simultaneously.7. In conclusion, we demonstrate that formation of endogenous BK contributes primarily to the acute,but not to the delayed hypotension afforded by endotoxin in the rat. In contrast, formation of endogenous PAF contributes to both the acute and the delayed hypotension afforded by endotoxin in vivo.

Amino Acid Sequence↗

PubMed1995

Responses of brown adipose tissue activity to unloading in rats.

To study the responses of thermogenic activity in brown adipose tissue (BAT) to unloading, male Wistar rats were hindlimb suspended for 10 days. Compared with control rats, a significant increase in the BAT-to-body mass ratio and considerable differences in chemical components in BAT were observed in the hindlimb-suspended rats. These findings indicate a marked increase in the thermogenic capacity in BAT of the experimental group. Likewise, the thermogenic activity (which was assessed by guanosine 5'-diphosphate binding to BAT mitochondria) was markedly greater in the mitochondria recovered from BAT of the hindlimb-suspended rats than in those from the control rats (1,610 +/- 450 vs. 202 +/- 132 pmol recovered). Moreover, the uncoupling protein content in the BAT mitochondrial fraction of the hindlimb-suspended rats was significantly higher (1.6-fold) than that in the control rats. As was expected, the uncoupling protein mRNA expression was greater in hindlimb-suspended rats than in control animals. These results suggest that chronic hindlimb suspension leads to an increase in both the thermogenic capacity and the activity in BAT of rats.

Adipose Tissue, Brown↗

PubMed1995

Insulin stimulates the expression of basic fibroblast growth factor in rat brown adipocyte primary culture.

The effect of insulin on the hyperplasia of brown adipose tissue (BAT) was investigated using the primary culture of rat brown adipocyte precursor cells (RBAC). Results showed insulin to significantly increase the number of RBAC, but not bovine capillary endothelial cells, in the presence of fetal bovine serum. Insulin also increased the expression of basic fibroblast growth factor (bFGF) mRNA and the related protein in the primary culture of RBAC. In addition, insulin enhanced the capillary growth in an in vitro angiogenesis model in which microvascular fragments and RBAC isolated from rat BAT were grown in coculture. The level of bFGF-related protein in the coculture was higher in the presence of insulin than in the absence of insulin. These findings suggest that insulin may play an important role in the proliferation as well as in the differentiation of brown adipocytes, with resulting hyperplasia of BAT (including the formation of new capillaries) through increased production of bFGF in brown adipocytes.

Adipocytes↗

PubMed1995

Norepinephrine stimulates the expression of fibroblast growth factor 2 in rat brown adipocyte primary culture.

To elucidate the role of norepinephrine (NE) in the hyperplasia of brown adipose tissue (BAT), we investigated the effects of NE on the expression of fibroblast growth factor-2 (FGF-2) in rat brown adipocyte primary culture and on capillary growth in an in vitro angiogenesis model in which microvascular fragments and brown adipocyte precursor cells isolated from rat BAT were grown in coculture. NE significantly increased the number of brown adipocyte precursor cells. The NE effect on cell proliferation was greatly inhibited by anti-FGF-2-specific antibody. Likewise,NE considerably increased the levels of FGF-2 mRNA and the antigen in brown adipocyte primary culture. The ability of NE to stimulate the expression of FGF-2 mRNA was blocked by actinomycin D or was inhibited partly by propranolol. Moreover, NE considerably increased the in vitro capillary growth and the level of FGF-2 antigen in the coculture. These results suggest that NE is a crucial factor to mediate FGF-2 production, in part via the beta-adrenergic receptor, in rat brown adipocytes and to stimulate the cell proliferation and capillary growth in BAT by an autocrine/paracrine mechanism.

Adipocytes↗

PubMed1995

[Clinical studies in five cases of Swyer-James syndrome].

We encountered five patients with Swyer-James syndrome. All were men, and ranged in age from 20 to 70 years (mean, 41 years). Their chest X-ray films showed left unilateral hyperlucency. Examinations revealed bilateral involvement in 3 cases and irregularity of involved regions in 2 cases. Chest CT scans revealed the distribution and severity of affected regions in greater detail than did other radiologic exams. Delayed clearance of xenon is a sign of air trapping, which is characteristics of this syndrome. Thus, 133Xe inhalation scintigrams were useful to detect air trapping, especially when mediastinal shift was not apparent on chest X-ray films. Bronchial damage is believed to cause this syndrome, and the present findings support this view. It is noteworthy that all five of these patients were men, and that in all five the affected lung was on the left. Moreover, although "respiratory tract infection is considered to be a very important" factor, many patients had no history of airway infection in childhood. Thus, some congenital factor or factors may contribute to the development of this syndrome.

Adult↗

PubMed1994

Demonstration of derivation of rat urinary bradykinin from plasma low-molecular-weight kininogen: a study using kininogen-deficient rats.

The origin of urinary bradykinin was defined by use of plasma kininogen-deficient B/N-Katholiek rats, whose ureter urine contains very low amount of urinary kinin. The kinin level increased after the rats received an infusion of normal plasma. Furthermore, the bradykinin content in the ureter urine of these kininogen-deficient rats increased more by infusion of partially purified rat- low-molecular-weight kininogen than by that of high-molecular-weight kininogen. Urinary kallikrein activity of B/N-Katholiek rats was enzymatically identical with that of normal B/N-Kitasato rats. These results indicate that urinary bradykinin found in the ureter urine of normal rats is derived from plasma low-molecular-weight kininogen by cleavage by urinary kallikrein.

Animals↗

PubMed1994

Differential effects of indomethacin and dexamethasone on cytokine production in carrageenin-induced rat pleurisy.

The effect of anti-inflammatory drugs on cytokine production at local inflammatory sites was investigated in a carrageenin-induced rat pleurisy model. Exudate volume and leukocyte number in the pleural cavity at 3 h after the carrageenin injection were significantly reduced by the pretreatment with indomethacin or dexamethasone. Both drugs also reduced the prostaglandin E2 level in the exudate. However, production of tumor necrosis factor (TNF) and interleukin-1 in the pleural exudate was significantly enhanced by the pretreatment with indomethacin, whereas the interleukin-6 level was reduced. Pretreatment with dexamethasone markedly suppressed all these cytokine levels. When resident pleural cells were stimulated with lipopolysaccharide in vitro, the presence of exogenous prostaglandin E2 reduced the production of TNF and interleukin-1, while it increased that of interleukin-6 in a dose-dependent manner. These results suggest that prostaglandin E2 could be a regulating factor involved in cytokine production at the inflammatory site. Dexamethasone may express a direct suppressive action on cytokine production rather than an indirect regulatory action through prostaglandin E2 level.

Animals↗

PubMed1994

Oxidative stress induced by intermittent exposure at a simulated altitude of 4000 m decreases mitochondrial superoxide dismutase content in soleus muscle of rats.

The effects were examined of 6-month intermittent hypobaric (4000 m) exposure on the antioxidant enzyme systems in soleus and tibialis muscles of rats. At the end of the 6-month experimental exposure, the six rats in both the exposed group and the control group were sacrificed. Immunoreactive mitochondrial superoxide dismutase (Mn-SOD) contents were measured as well as the activities of antioxidant enzymes [Mn-SOD, cytosolic SOD (Cu,Zn-SOD), catalase (CAT), and glutathione peroxidase (GPX)]. Thiobarbituric acid-reactive substances (TBARS) were also determined as an indicator of lipid peroxidation. The high altitude exposure resulted in a marked increase in TBARS content in soleus muscle, suggesting increased levels of oxygen free radicals. Conversely, significant decreases in both Mn-SOD content and activity in soleus muscle were noted after exposure. Such trends were not noticed in tibialis muscle. On the other hand, no significant changes in Cu,Zn-SOD, CAT, or GPX were observed in either muscle. These results suggested that the increases in lipid peroxidation were most probably a result of decreased Mn-SOD function which was more depressed in oxidative than in glycolytic muscle.

Altitude↗

PubMed1994

Demonstration of high-molecular-weight kininogen in kininogen-deficient rat kidneys.

Brown Norway Katholiek (B/N-Ka) is a mutant rat strain deficient in plasma high-molecular-weight (HK) and low-molecular-weight kininogen (LK). It has been reported that the deficiency, caused by defective secretion of HK and LK by the liver, is associated with a point mutation of alanine (163) to threonine in the common heavy chain. In this report we demonstrate by specific radioimmunoassay that the amount of immunoreactive HK antigen in the B/N-Ka kidney was almost the same as that found in the normal Brown Norway rat (Brown Norway Kitasato, B/N-Ki). HK antigen in the kidneys of both strains was immunohistochemically localized at distal tubules with similar intensity in both strains. Among the subcellular fractions of the kidney homogenates, HK antigen was predominantly found in the microsomal fraction of both strains. To see whether this HK antigen is derived from plasma HK or is synthesized in the kidneys, we examined uptake of HK by the tubular cells after incubation with 125I-HK. Only 0.6% of the radioactivity of added 125I-HK was found in the tubular cells of both strains after a 60-min incubation. Messages of HK mRNA from both strains of rats were visualized by PCR at almost the same intensity. These results suggest that HK antigen found in the kidney may be derived mainly from biosynthesis in the kidney itself and partly from uptake of HK from blood. There was no difference in these features of HK between the kidneys of the deficient and the normal B/N rats.

Animals↗

PubMed1994

Hypertension induced by a nonpressor dose of angiotensin II in kininogen-deficient rats.

Brown Norway Katholiek rats with very low levels of plasma kininogens excreted a much smaller amount of kinin in the urine than normal rats of the same strain. The systolic blood pressure of 7-week-old kininogen-deficient rats (132 +/- 2 mmHg, n = 7) was not different from that of normal rats. Angiotensin II (Ang II) (20 micrograms/d SC) from 7 weeks of age for 2 weeks with a micro-osmotic pump caused significant increases in blood pressure (181 +/- 5 mm Hg, n = 7, 9 weeks old) in the deficient rats, although the same treatment induced no blood pressure increase in the normal rats. Also during this period, the deficient rats had significantly higher heart rates, tended to excrete less urinary sodium, and showed significantly higher sodium levels in serum, erythrocytes, and cerebrospinal fluid compared with the normal rats. Ang II increased urinary excretion of aldosterone in both deficient and normal rats (P < .05). Spironolactone treatment (50 mg/kg per day) for 7 days in deficient rats restored blood pressure and heart rate to normal levels and significantly reduced sodium levels in erythrocytes and cerebrospinal fluid. Subcutaneous infusion of bovine low-molecular-weight kininogen with an osmotic pump in Ang II-treated deficient rats induced significant reductions in blood pressure, heart rate, and erythrocyte sodium levels. By contrast, subcutaneous infusion of the bradykinin antagonist Hoe 140 in Ang II-treated normal rats induced a hypertensive response in parallel with significant increases in heart rate and erythrocyte sodium level. These results suggest that the lack of kinin generation observed in the kininogen-deficient rats may cause the hypertensive response during the administration of a nonpressor dose of Ang II mainly through sodium retention probably caused by aldosterone release.

Aldosterone↗

PubMed1994

Molecular mechanism of kininogen deficiency in brown Norway Katholiek rats.

1. The Brown Norway (B/N) Katholiek rat is a mutant strain of plasma kininogen deficiency. The plasma of B/N-Katholiek rats was shown to contain only 3-5% of high-molecular-weight and low-molecular-weight kininogens (HK and LK) of the normal level by specific RIA, and 30% of prekallikrein was detected by amidase activity. However, HK antigen in the liver microsomal fraction of B/N-Katholiek rats was about 60% of that of normal rats. 2. In this paper we compare and discuss synthesis and secretion of HK and LK by primary cultures of livers of deficient and normal rats. The deficient hepatocytes could synthesize HK and LK in the same way as normal cells but could not secrete mature forms of HK and LK in the medium. Examination of the subcellular localization of the mutant HK in the hepatocytes showed that a larger amount of mutant HK antigen, compared to normal rats, was found in the 10,000 g fraction, which is rich in lysosomes, suggesting that the mutant HK may be transported to the lysosomes. 3. We also analyzed sequence of the HK cDNA of B/N-Katholiek and B/N-Kitasato rats and found a point mutation of G to A at nucleotide 487, which locates at the heavy chain region of HK and LK. 4. We constructed five expression plasmids to transfect COS-1 cells to examine HK secretion. COS-1 cells transfected with the plasmids containing the G to A transition could not secrete and retained HK, while those cells transfected with the plasmids containing normal G released HK into the medium. 5. These results indicate that a point mutation G to A at nucleotide 487, resulting in an amino acid transition from alanine (163) to threonine, is responsible for the defective secretion of HK and LK by the liver of B/N-Katholiek rats. We also discuss other cases of secretion defect of plasma proteins reported in the literature.

Animals↗