Evidence-based information is not a conspiracy to limit insurance benefits

J Evid Base Dent Pract 2001;1:5     

Lovastatin reduces renal vascular reactivity in spontaneously hypertensive rats

We have reported that lovastatin attenuates the development of hypertension in spontaneously hypertensive rats (SHR). The fall in arterial pressure is associated with an elevation in renal medullary blood flow, normalization of the pressure-natriuresis relationship, and diminished hypertrophy of renal arterioles. However, the mechanism by which lovastatin alters renal vascular tone is unknown. The present study examined the effects of lovastatin on renal vascular tone and the expression of G proteins. Four-week–old SHR were chronically treated with lovastatin (20 mg/kg/day) or vehicle by gavage for 4 weeks. At the end of the study, mean arterial pressure averaged 131 ± 4 (n = 5) and 160 ± 4 mm Hg (n = 6) in lovastatin- and vehicle-treated SHR, respectively. Renal arterioles isolated from lovastatin-treated SHR were significantly less responsive to norepinephrine and vasopressin than those obtained from vehicle-treated rats (ED₅₀: 5.0 v 1.8 × 10⁻⁷ mol/L for norepinephrine, and 8.0 v 5.2 × 10⁻¹⁰ mol/L for vasopressin). The fall in renal vascular reactivity in lovastatin-treated SHR was associated with reduced levels of ras and rho proteins in renal arterioles, whereas the expressions of heterotrimeric G proteins (G_s, G_q, G_i) were similar in renal arterioles from vehicle- and lovastatin-treated SHR. Overnight culture of renal arterioles with media containing lovastatin also diminished the expression of ras and rho proteins and the response to vasoconstrictors. These findings indicate that lovastatin diminishes the response to vasoconstrictors and the expression of small G proteins in the renal vasculature of SHR and suggest that a fall in the levels of ras and rho proteins in these vessels may contribute to the antihypertensive effects of lovastatin.     

卵母细胞中线粒体相关内质网膜结构与功能的研究进展

在卵母细胞发育成熟过程中,各细胞器之间有效、稳定的交流是保证其功能与质量的基础.内质网作为细胞钙储池,通过耦联结构与线粒体外膜相连,传递Ca2+信号,我们称该结构为线粒体相关内质网膜(Mitochondria associated membrane,MAM).MAM在调控内质网应激、线粒体功能、细胞凋亡等生理活动以及神...     

Differential Effects of Amlodipine on Ambulatory Blood Pressure in Elderly Hypertensive Patients With Different Nocturnal Reductions in Blood Pressure

Previous studies have discovered that amlodipine given once daily can reduce blood pressure (BP) throughout the day and night. The effects of amlodipine on day and night BP have not been fully investigated in groups of hypertensives with different diurnal variations. In a prospective study, we performed 24-h ambulatory BP monitoring before and after once-daily use of amlodipine in three groups of asymptomatic elderly hypertensive patients with different nocturnal BP reductions, as follows: 10 extreme dippers with nocturnal reduction of systolic BP ≥ 20% of daytime systolic BP, 17 dippers (reduction by ≥ 10% to < 20%), and 23 nondippers (reduction by < 10%). At baseline, the office and the awake BP were similar in all three groups, whereas the nighttime BP was significantly higher in the nondippers than in the dippers and in the dippers than in the extreme dippers. After treatment, the office and the daytime BP were both equally reduced in all three groups. On the other hand, the nighttime BP was significantly reduced both in the nondippers and, to a lesser extent, in the dippers. In the extreme dippers, however, no further reductions of nocturnal BP were found. Significant positive correlations were found between baseline BP levels and the BP reduction after amlodipine therapy was begun. No BP reduction > 10 mm Hg was observed when the baseline systolic/diastolic BP was < 120/70 mm Hg. Multiple linear regression analysis disclosed that the nighttime BP reduction afforded by amlodipine was dependent on the baseline nighttime BP levels, but not on the baseline nocturnal fall of BP. Once-daily use of amlodipine reduced BP levels throughout the day and night in hypertensive patients who show minimal or mild nocturnal BP fall, but it had no effects on nocturnal BP in those who show a substantial nighttime BP reduction. Thus, when we controlled using daytime office BP, amlodipine might not further reduce nocturnal BP to the extent that it accelerates the brain ischemia in some hypertensive patients with marked nocturnal BP reduction.     

ROC assessment of compressed wrist radiographs

The aim of this paper is to validate a compression scheme applied on a medical image database of digitized wrist radiographs. The compression scheme adapts itself to local statistical properties of the images. The diagnostic quality of the reconstructed images is evaluated using a ROC protocol involving five medical experts. The results of this evaluation enable us to validate the compression scheme on this database with a compression ratio of 40 (0.2 bits per pixel).