Biomedical subjects

J Obata

Publications and source records attributed to J Obata.

At least 19 recordsLinked to original sources

PubMed2004

Atypical cause of hibernating myocardium due to complex cardiovascular lesions associated with Takayasu's arteritis.

Myocardial hibernation is recognised as chronic hypoperfusion of the myocardium and its functional recovery after surgical revascularisation has been described. A case of surgery for complex lesions including severe aortic valve regurgitation, coronary ostial stenosis, and aortic calcification (porcelain aorta) caused by Takayasu's arteritis is presented. The onset of left ventricular functional improvement after aortic valve replacement and coronary revascularisation were indicative of preoperative atypical myocardial hibernation caused by aortic valve disease and coronary artery disease associated with Takayasu's arteritis.

Aortic Diseases↗

PubMed2001

p48 subunit of mouse PTF1 binds to RBP-Jkappa/CBF-1, the intracellular mediator of Notch signalling, and is expressed in the neural tube of early stage embryos.

BACKGROUND: Development of the pancreas and the nervous tissues is regulated by common transcription factors. A basic helix-loop-helix protein, p48 of pancreas transcription factor 1 (PTF1), is essential for differentiation of the exocrine acinar cells. RESULTS: We isolated PTF1 p48 from 9.5-day mouse embryos as a binding protein of RBP-Jkappa, a mediator of Notch signalling. p48 bound to RBP-Jkappa more strongly than and in a distinct way from Notch1. In 9.5-12.5 day embryos, p48 was expressed in the dorsal part of the neural tube as well as in the pancreatic buds. Two lines of evidence suggested functions of p48 in neurogenesis: (i) expression of p48 was induced in P19 cells when they committed to neural fate upon retinoic acid treatment, and (ii) p48 over-expressed in Xenopus embryos repressed the development of neuronal precursors. p48 inhibited the MASH1-activated transcription from the E-box, while p48 stimulated transcription from the PTF1 motif synergistically with E47. The p48/E47-activated transcription from the PTF1 motif was stimulated further by RBP-Jkappa and RBP-Jkappa derivatives that mimicked the active RBP-Jkappa/Notch complex. CONCLUSIONS: In developing embryos, p48 is expressed in both the nervous system and the pancreas. p48 inhibits neuronal differentiation. We propose possible mechanisms for this inhibition.

3T3 Cells↗

PubMed2000

Increased gene expression of components of the renin-angiotensin system in glomeruli of genetically hypertensive rats.

OBJECTIVE: The renin-angiotensin system (RAS) is implicated in the development of hypertensive glomerulosclerosis. However, no experimental evidence exists that clearly demonstrates activation of glomerular RAS in hypertensive nephropathy. We used stroke-prone spontaneously hypertensive rats (SHRSP) to examine whether RAS components are increased in glomeruli of SHRSP and whether this increase leads to an increase in mRNA levels for transforming growth factor-beta1 (TGF-beta1). METHODS: We examined the sequential changes of urinary albumin excretion (UAE), morphology, and glomerular mRNA expression for TGF-beta1 and fibronectin (FN) in relation to glomerular mRNA expression for angiotensinogen (ATN), angiotensin converting enzyme (ACE), angiotensin II type 1a (AT1a), and type 1b (AT1b) receptors, and intervention with angiotensin II type 1 receptor antagonist candesartan and equihypotensive hydralazine. RESULTS: In SHRSP, UAE was normal at 9 weeks of age, but became higher, beginning at 12 weeks of age, than that in the age-matched Wistar-Kyoto (WKY) rats, while SHRSP showed no glomerulosclerosis until 14 weeks of age; it was marked at 24 weeks. Plasma renin activity and plasma angiotensin II level was equivalent in the 9- and 12-week-old SHRSP and the WKY rats; both parameters, however, were elevated in 24-week-old SHRSP as compared with age-matched control. RNase protection assays showed that glomerular levels of ATN, ACE, and AT1a and AT1b receptors mRNA were significantly increased in 9-, 12-, and 14-week-old, but not in 24-week-old SHRSP, compared with age-matched WKY rats. Northern blot analysis showed that glomerular levels of TGF-beta1 and FN mRNA were higher in SHRSP than in WKY rats at all time points. Candesartan reduced UAE to control levels, whereas hydralazine reduced UAE but not to control levels. Candesartan administration for 12 weeks virtually prevented the progression of glomerulosclerosis. While candesartan reduced mRNA levels for RAS components, TGF-beta1, and FN to control levels, hydralazine was not effective in this respect. Conclusion Results suggest that increases in glomerular RAS components that occur independently of circulating RAS alter glomerular permselectivity and increase the glomerular expression of TGF-beta1 and FN in young SHRSP. Findings in old SHRSP suggest that altered glomerular permselectivity and an increased glomerular expression of TGF-beta1 and FN may be associated with the activation of systemic RAS.

Albuminuria↗

PubMed2000

In-hospital mortality after acute myocardial infarction in patients with diabetes mellitus.

OBJECTIVES: To examine in-hospital mortality after acute myocardial infarction in patients with diabetes mellitus. METHODS: All patients in an 800-bed teaching hospital who had a discharge diagnosis of myocardial infarction, verified by creatine kinase levels at admission, between 1991 and 1993 made up the study population. All 118 such patients who died during this period made up the case group. Two control subjects (n = 236), survivors of the hospitalization, matched by sex, age, and length of hospitalization, were selected randomly for each case. Information on the presence of diabetes mellitus, medical history, and data related to myocardial infarction were obtained through retrospective chart review. RESULTS: The mean age of all subjects in the study was 76 years. Thirty-three percent of the patients in the case group and 31% of the control subjects had a history of diabetes mellitus (odds ratio = 1.04; 95% CI, 0.64-1.70), indicating that diabetes mellitus was not associated with an increased risk of in-hospital death. The adjusted odds ratio was 1.10 (95% CI, 0.48-2.51) in patients with non-insulin-treated diabetes mellitus and 0.80 (95% CI, 0.34-1.86) in insulin-treated patients. Multivariate analysis, with conditional logistic regression, confirmed that known prognostic factors for myocardial infarction, rather than diabetic status, are predictive of in-hospital mortality. CONCLUSIONS: Once the effects of age are accounted for, the risk of in-hospital mortality is not greater in patients with diabetes mellitus than in patients without diabetes; however, diabetes mellitus may be an important factor for long-term survival.

Adult↗

PubMed1999

Blocking angiotensin II ameliorates proteinuria and glomerular lesions in progressive mesangioproliferative glomerulonephritis.

BACKGROUND: The renin-angiotensin system is thought to be involved in the progression of glomerulonephritis (GN) into end-stage renal failure (ESRF) because of the observed renoprotective effects of angiotensin-converting enzyme inhibitors (ACEIs). However, ACEIs have pharmacological effects other than ACE inhibition that may help lower blood pressure and preserve glomerular structure. We previously reported a new animal model of progressive glomerulosclerosis induced by a single intravenous injection of an anti-Thy-1 monoclonal antibody, MoAb 1-22-3, in uninephrectomized rats. Using this new model of progressive GN, we examined the hypothesis that ACEIs prevent the progression to ESRF by modulating the effects of angiotensin II (Ang II) on the production of transforming growth factor-beta (TGF-beta) and extracellular matrix components. METHODS: We studied the effect of an ACEI (cilazapril) and an Ang II type 1 receptor antagonist (candesartan) on the clinical features and morphological lesions in the rat model previously reported. After 10 weeks of treatment with equihypotensive doses of cilazapril, cilazapril plus Hoe 140 (a bradykinin receptor B2 antagonist), candesartan, and hydralazine, we examined systolic blood pressure, urinary protein excretion, creatinine clearance, the glomerulosclerosis index, and the tubulointerstitial lesion index. We performed a semiquantitative evaluation of glomerular immunostaining for TGF-beta and collagen types I and III by immunofluorescence study and of these cortical mRNA levels by Northern blot analysis. RESULTS: Untreated rats developed massive proteinuria, renal dysfunction, and severe glomerular and tubulointerstitial injury, whereas uninephrectomized control rats did not. There was a significant increase in the levels of glomerular protein and cortical mRNA for TGF-beta and collagen types I and III in untreated rats. Cilazapril and candesartan prevented massive proteinuria, increased creatinine clearance, and ameliorated glomerular and tubulointerstitial injury. These drugs also reduced levels of glomerular protein and cortical mRNA for TGF-beta and collagen types I and III. Hoe 140 failed to blunt the renoprotective effect of cilazapril. Hydralazine did not exhibit a renoprotective effect. CONCLUSION: These results indicate that ACEIs prevent the progression to ESRF by modulating the effects of Ang II via Ang II type 1 receptor on the production of TGF-beta and collagen types I and III, as well as on intrarenal hemodynamics, but not by either increasing bradykinin activity or reducing blood pressure in this rat model of mesangial proliferative GN.

Angiotensin II↗

PubMed1997

Candesartan prevents the progression of mesangioproliferative nephritis in rats.

We previously reported a new animal model of progressive glomerulonephritis induced by a single intravenous injection of the anti-Thy-1 monoclonal antibody MoAb 1-22-3 into uninephrectomized rats (Clin Exp Immunol 102: 181-185, 1995). We examined the effects of angiotensin II (Ang II) receptor antagonist (candesartan) on the clinical features and morphological lesions of this new model. By 10 weeks after induction of nephritis, untreated rats had developed hypertension, massive proteinuria, renal dysfunction, and severe glomerular injury, while uninephrectomized control rats had not. There was a significant increase in levels of glomerular protein and cortical mRNA for transforming growth factor-beta (TGF-beta) and type I and type III collagens in untreated nephritic rats. Ten week treatments with candesartan and hydralazine significantly reduced blood pressure (BP) to an equal extent. Candesartan, but not hydralazine, prevented proteinuria, normalized renal function, and ameliorated glomerular injury. Candesartan also reduced levels of glomerular protein and cortical mRNA for TGF-beta and type I and type III collagens, while hydralazine did not. These findings suggest that candesartan prevents progression to end-stage renal failure by modulating the effects of Ang II at least in part on the production of TGF-beta and type I and type III collagens, and not merely on systemic BP.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1997

Candesartan prevents the progression of glomerulosclerosis in genetic hypertensive rats.

The renin-angiotensin system (RAS) has been implicated in the development of hypertensive glomerulosclerosis. However, there are no experimental findings clearly demonstrating activation of glomerular RAS in hypertensive nephropathy. Using the stroke-prone spontaneously hypertensive rat (SHRSP) as an animal model of hypertensive glomerulosclerosis, we examined the relationship between the sequential changes in urinary albumin excretion (UAE), renal morphology, and glomerular mRNA expression for transforming growth factor-beta (TGF-beta) and fibronectin (FN) and glomerular mRNA levels for RAS components, and determined the effects of the angiotensin II (Ang II) type 1 (AT-1) receptor antagonist (candesartan) and equihypotensive hydralazine on these parameters. In SHRSP, UAE was normal at nine weeks of age and increased by 12 weeks. Plasma renin activity, plasma Ang II concentration, and angiotensin converting enzyme (ACE) activity were not higher in 9- and 12-week-old SHRSP than in WKY. RNase protection assay revealed higher glomerular mRNA levels for angiotensinogen, ACE, and AT-1a and AT-1b receptors in 9-, 12-, and 14-week-old SHRSP than in WKY. The glomerular mRNA levels for TGF-beta and FN in SHRSP were increased from nine weeks of age. SHRSP had a greater glomerulosclerosis index (GSI) at 24 weeks of age than did WKY. Administration of candesartan for two weeks, but not of hydralazine, markedly reduced UAE and normalized mRNA levels for TGF-beta, FN, and RAS components. Candesartan administration for 12 weeks virtually prevented the progression of glomerulosclerosis in rats. We conclude that in SHRSP, RAS activation and increased sensitivity to Ang II in glomeruli play important roles in the progression of glomerulosclerosis.

Albuminuria↗

PubMed1996

Involvement of angiotensin II in glomerulosclerosis of stroke-prone spontaneously hypertensive rats.

Renal plasma flow (RPF), glomerular filtration rate (GFR), glomerular pathology and glomerular TGF-beta gene expression were examined in 12- and 24-week-old stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar Kyoto rats (WKY). These parameters were also examined in SHRSP treated with equihypotensive doses of angiotensin II receptor antagonist (CV-11974:CV) and hydralazine (Hyd) for 12 weeks. Twelve-week-old SHRSP showed a decrease in RPF and GFR, and an increase in filtration fraction (FF) and urinary protein excretion (UP) compared to WKY. CV normalized these parameters, whereas although Hyd showed improved levels they were not to the levels achieved by the WKY. Glomerular TGF-beta expression was increased 2.0-fold in 12- and 24-week-old SHRSP, and CV, but not Hyd, decreased it to the control levels of WKY. At 24 weeks old, SHRSP showed a higher glomerulosclerosis index (GI) than WKY. CV, but not Hyd, lowered the GI to the level of the WKY controls. These data indicate that renal hemodynamic changes are closely associated with an increased TGF-beta expression in SHRSP and that this condition is caused by angiotensin II.

Angiotensin II↗

PubMed1996

[Evaluations of a specified number of inhalations and how to assess the contents in metered-dose inhalers].

Many kinds of Metered-Dose Inhalers (MDI) have been clinically available for bronchial asthma. Although manufacturers demonstrate the specified number of inhalations per canister on an attached document or on a plastic bag, the information provided are usually inadequate and inconsistent. They provide no information on the problems of the Metered-Dose Inhalers beyond the maximum specified number of actuations and the time when to exchange for a new one. We examined the technique how to evaluate the contents of MDI and their accuracy. Patients and their parents depended on inaccurate methods, such as shaking the inhalers to listen to the sound of contents, estimating the weight of the canisters and the size of emissions, and only a half of them were able to distinguish between 1/3 and 2/ 3 of remaining doses. Three Metered-Dose Inhalers with anti-inflammatory drugs and one MDI with beta-stimulant supplied consistent doses until they reached the maximum specified number. The 4 MDIs floated in the water in different ways and provided information when to replace for new ones in some MDIs.

Adolescent↗

PubMed1994

Renal protective effects of angiotensin II receptor I antagonist CV-11974 in spontaneously hypertensive stroke-prone rats (SHR-sp).

This study was performed to examine the effects of blockade of the renin-angiotensin system on the development of hypertension and renal damage in stroke-prone spontaneously hypertensive rats (SHR-sp), using a non-peptide angiotensin II receptor antagonist, CV-11974. We examined changes in blood pressure, urinary protein excretion, creatinine clearance and renal morphology in CV-11974-treated SHR-sp rats and compared these variables with those in non-treated SHR-sp and Wistar Kyoto (WKY) rats, as well as in hydralazine-treated SHR-sp rats. CV-11974 lowered systolic blood pressure in a manner similarly to hydralazine (CV-11974 204 +/- 3, hydralazine 200 +/- 3, non-treated SHR-sp 284 +/- 9, WKY 155 +/- 5 mmHg), but reduced urinary protein excretion more than hydralazine (p < 0.01). There were no significant differences in creatinine clearance among experimental groups. The glomerulosclerosis index was greater in non-treated and hydralazine-treated SHR-sp rats than in CV-11974 treated SHR-sp and WKY rats (p < 0.01). Hydralazine-treated SHR-sp rats had a lower glomerulosclerosis index than the non-treated SHR-sp rats (p < 0.01). No significant differences were found in glomerulosclerosis index between CV-11974-treated SHR-sp and WKY rats. Tubular atrophy, tubular casts and interstitial fibrosis were observed in non-treated SHR-sp rats and, occasionally, in hydralazine-treated SHR-sp rats, but not in CV-11974-treated SHR-sp rats or WKY rats. These results indicate that the angiotensin II receptor antagonist was superior to hydralazine as far as renal protection was concerned. This suggests that renal damage in SHR-sp rats is associated not only with hypertension but also with activation of the renin-angiotensin system.

Angiotensin Receptor Antagonists↗

PubMed1993

Analgesic effect of Ga-Al-As diode laser irradiation on hyperalgesia in carrageenin-induced inflammation.

This study concerned the effect of Ga-Al-As diode laser irradiation (780 nm, continuous wave, 31.8 J/s/cm2, spot size od 0.2 mm, 3 minutes/dose) on hyperalgesia induced in the hind paw of rats by injecting carrageenin. The pressure-pain thresholds of hind paws were measured by the Randall-Selitto test for evaluation of hyperalgesia. Two doses of laser irradiation, given to the inflamed region immediately before and after the injection of carrageenin, partially (approximately 50%) inhibited the occurrence of hyperalgesia accompanied with a progression of inflammation. This analgesic effect was equal to that of indomethacin (4 mg/kg, i.o.). In another group, the hyperalgesia was removed almost completely for at least 24 hours by one dose of laser irradiation, which was given 3 hours after the carrageenin injection, whereas the edema was not inhibited. This analgesic effect, however, was partially (approximately 50%) antagonized with a dose of 10 mg/kg (i.p.) of naloxone and totally inhibited with 30 mg/kg. These results suggest that low-power laser irradiation on inflamed regions of carrageenin-treated rats has a marked analgesic effect and that certain mechanisms that are not related to endogenous opioids are involved in a part of the mechanisms of the analgesic effects.

Analgesia↗

PubMed1992

Therapeutic effect of Ga-Al-As diode laser irradiation on experimentally induced inflammation in rats.

We produced experimental inflammation models in rats by carrageenin and studied the effect of Ga-Al-As diode laser irradiation (780 nm, continuous wave, 31.8 j/sec/cm2, spot size of 0.2 mm) on inflamed regions compared with those of indomethacin, a potent anti-inflammatory agent. We found that a low-power infrared laser has an anti-inflammatory effect on carrageenin inflammation. A low-power laser inhibits: (1) the increase of vascular permeability during the occurrence of an acute inflammation in the carrageenin-air-pouch model, (2) edema in the acute stage in the carrageenin-paw-edema model, and (3) the granuloma formation in the carrageenin-granuloma model after receiving laser irradiation once daily. In all cases, irradiation for less than 10 min was sufficient to inhibit the inflammation by 20-30%. The inhibitory effect of laser irradiation was not comparable to that of indomethacin (4 mg/kg, i.o.) in the air-pouch model and the paw-edema model, whereas laser irradiation was more potent than that of daily administration of indomethacin (1 mg/kg, i.o.) in the granuloma model. In future studies of the mechanism of laser effect, it should be noted that irradiating a rat twice, before and after the provocation of inflammation, was essential in order to achieve an effective inhibition of paw-edema.

Aluminum↗

PubMed1991

Structure/activity relationship of eel calcitonin. A study using a newly devised method for designing analogs.

A series of analogs of eel calcitonin (eCT) was synthesized according to a newly devised scheme, 'the insertion-inactivation method', to clarify the structure/activity relationship of a given peptide. This method consists of two steps: the deletion of a residue of the peptide is first chosen and then a series of analogs with the residue reinserted into serial positions is synthesized and biological activities are assessed in each step. An analog lacking Lys18 (dK), selected as a deleted analog for the first step, showed marked loss of activities determined by inhibition of 125I-eCT binding, growth inhibition, and cAMP production in a porcine kidney cell line LLC-PK1. Activities of a set of 20 analogs with the reinserted lysine residue at serial positions from 12 to 32 (K12-K32) were then evaluated. The results showed the following three patterns of the expression of activities according to the position of the reinsertion: (a) analogs K12-K16 (positions 12-16) and K25 (position 25) showed lower activities than eCT in all assays; (b) K17-K24 (positions 17-24) showed slightly lower activities than eCT in the receptor binding and the growth inhibition and similar level in cAMP production; (c) K26-K32 (positions 26-32) showed considerably lower activities in the former two assays and slightly lower activity in cAMP production. Further, analogs considerably less active than eCT showed unchanged alpha-helix contents and destroyed amphiphilicity by the insertion of a lysine residue, indicating that amphiphilicity is one of important factors for expressing the activity. The results obtained here lead to a conclusion on the significance of each region of eCT molecule as follows: (a) the presence of Lys18 is necessary for the complete expression of biological activity; (b) the length of amphiphilic alpha-helix to be required for the activity is at most 10 residues ranging from position 8 to position 17; (c) the receptor binding region is located within 9 residues ranging from position 24 to position 32.

Amino Acid Sequence↗

PubMed1985