Spreading of silicone oils on glass in two geometries.

A basic problem in liquid spreading is the hydrodynamic description of the viscous breaking force near the moving contact line. A solution to the problem of divergence at the triple line has been illustrated with two experimental configurations. It consists of observing that the rheological behavior of a Newtonian liquid is modified near the triple line due to high shear rates. Above a critical value of the shear rate, near the triple line and near the solid surface, the liquid becomes shear-thinning, meaning that the apparent viscosity of the liquid decreases as the shear rate increases. As a result, there is no divergence of the viscous energy dissipation and of the braking force as observed for a purely Newtonian behavior. This description of the viscous braking phenomenon in liquid spreading is well supported by spreading experiments of silicone oils on glass substrates in two different wetting configurations. The liquids used are two silicone oils (10,000 and 100,000 cSt). These liquids are Newtonian below a critical value of the shear rate. Above this critical value, the liquid viscosity decreases according to a power law of the shear rate. One series of experiments consider the spreading of silicone oil droplets on treated and untreated glass substrates. The other configuration consists of using the glass substrates as Wilhelmy plates and to determine the advancing dynamic contact angle as a function of the imposed speed of sinking of the plate into oil reservoirs. The two series of experiments satisfy the same dynamic wetting laws. The overall experimental results are compatible with the hypothesis of a Newtonian/non Newtonian transition of the rheological properties of liquids near the wetting front although the main origin of dissipation appears to result from Newtonian viscous braking. The same dynamic law applies for the drop and Wilhelmy plate geometries.

Functional GPCR microarrays.

This paper describes G-protein-coupled receptor (GPCR) microarrays on porous glass substrates and functional assays based on the binding of a europium-labeled GTP analogue. The porous glass slides were made by casting a glass frit on impermeable glass slides and then coating with gamma-aminopropyl silane (GAPS). The emitted fluorescence was captured on an imager with a time-gated intensified CCD detector. Microarrays of the neurotensin receptor 1, the cholinergic receptor muscarinic 2, the opioid receptor mu, and the cannabinoid receptor 1 were fabricated by pin printing. The selective agonism of each of the receptors was observed. The screening of potential antagonists was demonstrated using a cocktail of agonists. The amount of activation observed was sufficient to permit determinations of EC50 and IC50. Such microarrays could potentially streamline drug discovery by helping integrate primary screening with selectivity and safety screening without compromising the essential functional information obtainable from cellular assays.

Changes in renal blood flow reserve after angioplasty of renal artery stenosis in hypertensive patients.

BACKGROUND: Intra-arterial Doppler is a recent technique which allows assessment of distal vascular disease using measurements of intrarenal blood flow velocities. The purpose of this study was to evaluate intrarenal hemodynamics and renal blood flow reserve before and after percutaneous transluminal angioplasty (PTA) in hypertensive patients with unilateral atherosclerotic renal artery stenosis using intra-arterial Doppler. METHODS: Intra-arterial Doppler was performed during arteriography in 19 hypertensive patients (12 men; mean age, 64 +/- 8 years) in "normal" and in "stenotic" kidneys at baseline, on isosorbide dinitrate, and after selective intra-renal papaverine injection, before, and after PTA. Doppler parameters analyzed were average peak velocity, maximum peak velocity, end diastolic velocity, and renal blood flow (RBF). Changes in Doppler parameters after papaverine injection were also analyzed. RESULTS: The major results were (1) the significant reduction in RBF distal to the stenosis, (2) the lack of arteriolar reactivity in response to papaverine distal to the stenosis, (3) the immediate recovery of arteriolar reactivity after PTA, associated with restoration of RBF in the revascularized kidneys, and (4) no change in arteriolar reactivity in response to papaverine in the "normal" kidneys following PTA. CONCLUSION: Ours results highlighted the benefit of endovascular Doppler to evaluate (1) RBF reserve, and (2) the repercussion of the stenosis on the distal vascularization.

Molecular interactions between DNA and an aminated glass substrate.

With the development of DNA arrays, the immobilization of DNA strands onto solid substrates remains an essential research topic. DNA arrays have potential applications in DNA sequencing, mutation detection, and pathogen identification. DNA bound to solid substrates must still be accessible and retain the ability to hybridize with its complementary strands. One technology to produce these arrays involves linking DNA molecule probes to a silanized substrate in microspot patterns and exposing them to a solution of fluorescently labeled samples of DNA targets. The behavior of both the target and probe DNA and their interactions with each other at the substrate surface, particularly with respect to molecular interactions, are poorly understood at the present time. The objective of this work is to model simply the interface interactions between DNA and glass slides modified with an aminosilane (gamma-aminopropyltriethoxysilane, APTS). In aqueous solutions, DNA behaves as a polyacid over a wide range of pH. A glass substrate treated with APTS is positively or negatively charged, depending on the pH. A model of the surface charge of APTS-treated glass has been developed from results of wetting experiments performed at various pH. It has been demonstrated that the surface charge of APTS-treated glass is well described by a model of constant capacitance of the electrical double layer. A good correlation between experimental data on DNA retention at various pH's and the variation of the surface charge of the APTS-treated glass is obtained. This provides an indication of the role of ionic interactions in the adsorption of DNA molecules onto aminated glass slides.

Parenchymal consequences of fibromuscular dysplasia renal artery stenosis.

PURPOSE: The aim of this study is to assess parenchymal consequences of fibromuscular dysplasia (FMD) renal artery stenosis (RAS) in hypertensive patients by spiral computed tomographic angiography (CTA). METHODS: Spiral CTA was performed in 20 essential hypertensive (EH) patients (40 EH kidneys and 20 hypertensive patients with unilateral FMD stenosis (20 poststenotic [S] kidneys, 20 opposite [OPP] kidneys). Renal length (RL; in millimeters), mean cortical thickness (MCT; in millimeters), cortical area (CA; in square millimeters), and medullary length (ML; in millimeters) were evaluated. RESULTS: Blood pressure, creatinine clearance, and long-standing hypertension were similar in both groups of patients. Compared with EH kidneys, S and OPP kidneys showed significant cortical thinning (MCT(EH) = 9.2 +/- 0.8 mm versus MCT(OPP) = 7.8 +/- 1.0 mm versus MCT(S) = 7.3 +/- 1.0 mm; P < 0.0001). RL and ML were reduced only in the S kidney group, with RL(EH) = 103 +/- 11 mm versus RL(OPP) = 105 +/-10 mm versus RL(S) = 96 +/- 11 mm; P = 0.05; and ML(EH) = 84 +/- 11 mm versus ML(OPP) = 89 +/- 9 mm versus ML(S) = 81 +/- 10 mm; P = 0.05, respectively. CA and MCT correlated significantly with creatinine clearance in the entire population (r = 0.43; P = 0.005; r = 0.35; P = 0.02, respectively). CONCLUSION: Unilateral RAS was associated with bilateral cortical thinning in FMD disease. Cortical atrophy appears to be an accurate marker of unilateral RAS. Its use as a potential screening method for RAS should be investigated further.

Renal atrophy outcome after revascularization in fibromuscular dysplasia disease.

PURPOSE: To assess clinical, biological, and kidney parameters before and 6 months after revascularization of renal artery stenosis due to fibromuscular dysplasia (FMD). METHODS: Twenty hypertensive patients (18 women; mean age 48.7 +/- 15.4 years) with unilateral de novo FMD stenosis were studied before and 6 months after revascularization (balloon angioplasty 19; bypass surgery 1). Blood pressure and creatinine clearance were measured, and renal length, cortical thickness, cortical area (CA), and medullary length (ML) were evaluated by spiral computed tomographic angiography (CTA) in 20 poststenotic and 20 contralateral kidneys. RESULTS: Six months after revascularization, the systolic and diastolic blood pressures decreased by 19 mmHg and 10 mmHg, respectively (p=0.02), the number of antihypertensive drugs decreased by 1 (p=0.01), but the increase in creatinine clearance was not significant. At baseline, the poststenotic kidneys were significantly more atrophied than the contralateral normal kidney (ML in normal kidney 89 +/- 9 mm versus 81 +/- 10 mm in poststenotic kidney, p<0.001; CA in normal kidney 824 +/- 149 mm(2) versus 703 +/- 156 mm(2) in poststenotic kidney, p<0.01), which persisted at 6 months (ML in normal kidney 89 +/- 10 versus 80 +/- 11 in poststenotic kidney, p<0.001; CA in normal kidney 807 +/- 145 mm(2) versus 696 +/- 157 mm(2) in poststenotic kidney, p<0.01). Renal length was still within normal range in all kidneys, and the morphological parameters remained stable after revascularization. CONCLUSIONS: We demonstrated significant cortical/medullary atrophy in poststenotic kidneys compared to contralateral normal kidneys. Despite intraparenchymal disease, clinical outcome was favorable after revascularization. Cortical/medullary thinning appears to be an early marker of renal ischemia that could support revascularization in FMD disease.

Cortical thickness: an early morphological marker of atherosclerotic renal disease.

BACKGROUND: Although kidney size is still the most commonly used morphological parameter, it is not sensitive enough for early detection of atherosclerotic renal disease (ARD). The purpose of this work was to evaluate morphological abnormalities on both post-stenotic and contralateral kidneys, by using spiral computed tomography angiography (CTA). METHODS: Spiral CTA was performed in 49 hypertensive patients. Renal diameters, renal length, and cortical thickness were measured in 26 post-stenotic kidneys, 26 contralateral kidneys and 46 control kidneys. Mean cortical thickness, cortical area, and medullary length were calculated. RESULTS: The right and left control kidneys were of comparable morphology. The post-stenotic kidneys showed significant cortical atrophy. The contralateral kidneys also underwent cortical disease, as judged by comparison with control kidneys. A threshold of 800 mm2 was identified for the cortical area that allowed us to distinguish control kidneys from post-stenotic kidneys. Similarly, a threshold of 8 mm was identified for mean cortical thickness. Renal length was still within normal range in all kidney groups. The measurement of superior pole segments appeared to be more sensitive than measurement at other locations for identifying significant intrarenal lesions. There was no significant correlation between clinical and morphological parameters. CONCLUSIONS: These results suggest that cortical parameters are more sensitive for early diagnosis of ARD than kidney size. Cortical atrophy should be a useful marker for guidance for revascularization.

Randomized, comparative, double-blind study of amlodipine vs. nicardipine as a treatment of isolated systolic hypertension in the elderly.

A 90-day, multicenter, randomized, double-blind, parallel-group study was conducted to compare the efficacy of amlodipine (once a day) with nicardipine (two to three times a day), in the treatment of isolated systolic hypertension (ISH) in the elderly. Patients (n = 133) aged > or = 60 years, with ISH were randomized to receive either amlodipine 5 mg/day, or nicardipine 60 mg/day (titrated if necessary to 10 mg/day and 100 mg/day, respectively) for 90 days. Efficacy was assessed by measuring office blood pressure (BP), and 24-h ambulatory blood pressure monitoring (ABPM). The two treatments substantially and comparably reduced office systolic blood pressure (SBP) and pulse pressure (PP), and also produced a slight decrease in diastolic blood pressure (DBP). Amlodipine reduced SBP, as assessed by ABPM, to a significantly greater extent than nicardipine. Both treatments were well-tolerated. The sustained effect of amlodipine, compared with nicardipine, was reflected in its significantly greater antihypertensive activity, particularly during the nocturnal period, as assessed by ABPM. The study demonstrates that once a day dose of amlodipine is an effective antihypertensive treatment for elderly ISH patients.

Renal atrophy in atherosclerotic renovascular disease: gradual changes 6 months after successful angioplasty.

OBJECTIVE: To assess renal morphology using spiral computed tomographic angiography (CTA) before and 6 months after angioplasty of unilateral atherosclerotic renal artery stenosis (RAS). METHODS: Spiral CTA scans from 14 hypertensive patients (7 men; mean age 57.4 +/- 13.1 years) with significant RAS were performed before and 6 months after angioplasty; renal length, mean cortical thickness (MCT), cortical area (CA), and medullary length (ML) were measured from the axial slices in the 14 contralateral and 14 poststenotic then revascularized kidneys. Blood pressure, creatinine clearance, and number of antihypertensive drugs were analyzed. RESULTS: At 6 months, the systolic blood pressure was significantly reduced (p=0.007), but the number of antihypertensive drugs and the creatinine clearance did not change significantly. Most morphological parameters before and after angioplasty were different in the contralateral versus poststenotic kidneys (renal length, p=0.01; MCT, p=0.01; ML, p=0.03; CA, p=0.008). After angioplasty, there was an 11% drop in cortical atrophy associated with a mean 4-mm increase in medullary length in the poststenotic/revascularized kidneys. The contralateral kidneys exhibited corticomedullary thinning after angioplasty. CONCLUSIONS: In atherosclerotic renal disease, cortical thinning could be a useful timesaving marker to assess the significance of the lesion and to evaluate associated distal lesions. The favorable blood pressure outcome supports the existence of reversible ischemic lesions, particularly in the medulla. Angioplasty appears to be useful for the poststenotic kidney, according to the morphological study.

On the Spreading of Glycerol Trioleate.

Spreading of liquids can often successfully be described by either hydrodynamic or molecular kinetics theories. The natural wetting of small, sessile drops of glycerol trioleate on smooth, flat, solid surfaces may be expected to comply with the former model, yet nonnegligible differences are manifest, which apparently cannot be accounted for by the addition of a molecular kinetics term. We postulate that modifications to the spreading rate are due to an effect of time-dependent molecular orientation occurring after liquid molecules have contacted the solid substrate. Copyright 2001 Academic Press.