PubMed · 11216190
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M McGregor. 2000-01-11. Reference-based pricing.. https://pubmed.ncbi.nlm.nih.gov/11216190/
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Dioscorin, the tuber storage protein of yam (Dioscorea alata cv. Tainong No. 1), was purified to homogeneity by DE-52 ion-exchange chromatography. This purified dioscorin was shown by spectrophotometric methods to inhibit angiotensin converting enzyme (ACE) in a dose-dependent manner (12.5-750 microg, respectively, 20.83-62.5% inhibitions) using N-[3-(2-furyl)acryloyl]-Phe-Gly-Gly (FAPGG) as substrates. The 50% inhibition (IC(50)) of ACE activity was 6.404 microM dioscorin (250 microg corresponding to 7.81 nmol) compared to that of 0.00781 microM (0.0095 nmol) for captopril. The commercial bovine serum albumin and casein (bovine milk) showed less ACE inhibitory activity. The use of qualitative TLC also showed dioscorin as ACE inhibitors. Dioscorin showed mixed noncompetitive inhibitions against ACE; when 31.25 microg of dioscorin (0.8 microM) was added, the apparent inhibition constant (K(i)) was 2.738 microM. Pepsin was used for dioscorin hydrolysis at 37 degrees C for different times. It was found that the ACE inhibitory activity was increased from 51.32% to about 75% during 32 h hydrolysis. The smaller peptides were increased with increasing pepsin hydrolytic times. Dioscorin and its hydrolysates might be a potential for hypertension control when people consume yam tuber.
BACKGROUND: Captopril renal scanning (CRS) is commonly recommended as a noninvasive method for detecting renal artery stenosis (RAS), based on performance characteristics determined in research settings. Scant data are available, however, regarding the utility of CRS in clinical practice. METHODS: We evaluated the performance characteristics (sensitivity, specificity, and predictive values) of CRS in a consecutive series of 90 patients who underwent both CRS and renal arteriography within a 6-month period (January 1, 1991, through December 31, 1995) at a university hospital. RESULTS: Among 86 eligible patients (and 169 kidneys), the prevalence of RAS was 43%. The sensitivity of CRS was 74% (95% confidence interval [CI], 62%-83%); the specificity was 59% (95% CI, 49%-69%); the positive predictive value was 58% (95% CI, 47%-68%); and the negative predictive value was 75% (95% CI, 64%-84%). Also, there was evidence of spectrum bias, because the sensitivity and specificity (as well as the positive and negative predictive values) were different for groups with and without vascular disease. CONCLUSIONS: The results of CRS were substantially worse in a clinical practice setting than previously reported in research settings, despite a similar prevalence of RAS. Captopril renal scanning should not be used as an initial screening test for diagnosing RAS, even among patients with high clinical likelihood of disease.
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