Yoshiyuki Konta

Purification and molecular cloning of mouse renal dipeptidase

Mouse renal dipeptidase (mouseRDP, EC 3.4.13.11) was purified from the membrane fraction of kidney. The molecular mass of the enzyme was 115 kDa by size-exclusion HPLC and SDS-PAGE under non-reduced conditions and 58 kDa by SDS-PAGE under reduced conditions. The mouseRDP cDNA fragment was amplified from mouse kidney total RNA by reverse transcription-polymerase ŏffin reaction (RT-PCR). The mouseRDP cDNA was isolated from a kidney cDNA library using the probe. The primary structure of mouseRDP deduced from the cDNA showed a high homology with renal dipeptidase from various mammals, except for the amino-terminal and carboxy-terminal domains. Recombinant mouseRDP obtained from transfected mouse L929 cells containing the expression plasmids has the same Km value and molecular mass as native mouse renal dipeptidase. From Northern blotting analysis, expression of the mouseRDP gene was recognized in both kidney and liver.

Novel pro-atherogenic molecule coupling factor 6 is elevated in patients with stroke: a possible linkage to homocysteine.

Abstract Background and purpose. Homocysteine (Hcy) is an independent predictor of stroke. Coupling factor 6 (CF6) is regulated by nuclear factor kappa B (NF-κB) signaling which is activated by Hcy. We tested the hypothesis that CF6 is elevated with Hcy in stroke. We also examined the effect of vitamin treatment on CF6 and Hcy levels. Methods and results. The 59 Japanese patients with a recent history of stroke were randomly assigned to a group without vitamin treatment (Group 1, n = 29) and to a group with treatment with both folic acid and vitamin B12 for 2 months (Group 2, n = 30). The CF6 level was elevated in the patients with stroke compared with that in controls (n = 64) at admission. In a multiple regression model, the plasma CF6 level was weakly correlated to the total Hcy (tHcy) level. In Group 1, the plasma tHcy and CF6 levels were unchanged. In Group 2, however, they were both decreased, and there was a weak positive correlation between the decreases in plasma levels of CF6 and tHcy. Conclusion. CF6 is elevated in patients with stroke independently of risk factors. Since Hcy and vitamin treatment affect CF6 levels in stroke, CF6 appears to be a novel molecule for the pathogenesis and treatment of stroke.

Cloning and structural analysis of genomic DNA for human renal dipeptidase.

A genomic DNA for human renal dipeptidase was isolated from a human genomic library using probes for human renal dipeptidase cDNA. The human renal dipeptidase gene, containing ten exons and nine introns, had a total length of approx. 6 kbp. The DNA sequence of these exons was slightly different from that of the human renal dipeptidase cDNA reported by Adachi et al. [1]. From the results of a comparison of the deduced amino acid sequence of each exon with various mammalian renal dipeptidases, the fourth exon was found to be highly conserved (90%).

Effect of losartan on nocturnal blood pressure in patients with stroke: comparison with angiotensin converting enzyme inhibitor

BACKGROUND Treatment of nocturnal hypertension has been reported to be beneficial for primary and secondary prevention of stroke. We compared the effects of angiotensin II antagonist (losartan) and angiotensin converting enzyme inhibitor (quinapril) on nocturnal blood pressure (BP) and sympathetic nervous activity in patients with hypertension and stroke. METHODS According to a prospective, randomized, cross-over design, 30 hypertensive patients with a previous history of stroke (25 hemorrhage, 5 infarction) were assigned randomly to receive losartan (50 mg) or quinapril (10 mg) once daily for 4 weeks. The patients were switched to the alternative regimen for an additional 4-week period. In the last week of each treatment, 24-h ambulatory BP monitoring was performed every 30 min, and 24-h urine was collected for the measurement of catecholamine. RESULTS Neither systolic nor diastolic BP during daytime differed between losartan and quinapril treatments, but those during nighttime were lower with losartan treatment than with quinapril treatment. The nocturnal decreases in systolic and diastolic BP were both greater with losartan treatment than with quinapril treatment (systolic BP: 6.1% +/- 5.9% v 2.5% +/- 6.9%, diastolic BP: 6.4% +/- 6.5% v 3.3% +/- 7.8%, both P <.05). The nocturnal decrease in urinary norepinephrine excretion was greater with losartan treatment than with quinapril treatment (52.8% +/- 9.7% v 42.8% +/- 17.2%, P <.05). CONCLUSIONS Losartan enhances the nocturnal decrease in ambulatory BP compared with that of quinapril in patients with a previous history of stroke presumably by way of the suppression of nocturnal sympathetic nervous activity.

Acceleration of platelet aggregability due to modulation of native LDL.

The aim of this experiment was to clarify whether low density lipoprotein (LDL) causes an acceleration of platelet aggregability. Native LDL was separated into two fractions by filtered tap-water dialysis, namely, water-soluble LDL (WS-LDL) and non-water-soluble LDL. Although native LDL did not enhance the platelet aggregability, WS-LDL made it markedly increased. WS-LDL consisted of the lipid constituents that were not found in native LDL. Namely, in thin-layer chromatography of WS-LDL, an unknown spot between triolein and free fatty acid was clearly stained. This unknown spot in the WS-LDL was produced by the peroxidation of cholesteryl ester in native LDL. It was confirmed that the spot has the same Rf value as the peroxidate of cholesteryl linolate in thin-layer chromatography. If native LDL is modulated by divalent metal ions and oxygen in the fluids, LDL with biological activity such as an increase of platelet aggregability is produced.

A new approach to prevention and treatment of atherosclerosis by dyslipoproteinemia.

A number of papers’.’ have been published on the treatment and prevention of atherosclerosis. The main points of those papers were to reduce the concentrations of low density lipoprotein cholesterol (LDL-CH), apoprotein B (apo B), and lipid peroxide (LPO) or to increase that of high density lipoprotein cholesterol (HDL-CH). Furthermore, in several human and nonhuman primate experiment^^.^ it was shown that atherosclerotic lesions regressed by reducing the concentration of LDL-CH for an extended period of time. Recently, Steinberg’ and Kitah reported that the foramtion of atheroma was suppressed in WHHL rabbits by probucol treatment. They pointed out that the suppression of LPO was more important for the treatment and prevention of atherosclerosis than the reduction of LDL-CH. In this paper, new aspects for the treatment and prevention of atherosclerosis will be discussed from the viewpoint of the composition and physical character of LDL.

Comparison of the effects of losartan and angiotensin converting enzyme inhibitor on nocturnal blood pressure in patients with stroke

Abstract Background : Therapy of nocturnal hypertension was shown to be beneficial for primary and secondary prevention of stroke. We investigated the effects of angiotensin II antagonist (losartan) and angiotensin converting enzyme (ACE) inhibitor (quinapril) on nocturnal blood pressure and sympathetic nervous activity in patients with hypertension and stroke. Methods : According to a prospective, randomized, crossover design, 30 hypertensive patients with a previous history of stroke were assigned randomly to receive losartan (50 mg) or quinapril (10 mg) once daily for 4 weeks. The patients were switched to the alternative regime for an additional 4-week period. In the last week of each treatment, 24-h ambulatory blood pressure (BP) monitoring was performed every 30 min, and 24-h urine was collected for the measurement of catecholamine. Results : Neither systolic nor diastolic BPs during daytime differed between losartan and quinapril treatments, but those during nighttime were lower under losartan treatment than under quinapril treatment. The nocturnal decreases in systolic and diastolic BPs were both greater under losartan treatment than under quinapril treatment. The nocturnal decrease in urinary norepinephrine (NE) excretion was greater under losartan treatment than under quinapril treatment. Conclusions : Losartan augments the nocturnal decrease in ambulatory BP compared with that of quinapril in patients with a previous history of stroke, presumably via the suppression of nocturnal sympathetic nervous activity.