Lercanidipine reduces matrix metalloproteinase-2 activity and reverses vascular dysfunction in renovascular hypertensive rats

Increased expression/activity of matrix metalloproteinases (MMPs), especially MMP-2, plays a role in the vascular alterations induced by hypertension, and increased oxidative stress is a major factor activating MMPs. Here, we hypothesized that lercanidipine, a calcium channel blocker, could attenuate the increases in oxidative stress and MMP-2 expression/activity in the two-kidney, one-clip (2K-1C) hypertensive rats. Sham-operated or 2K-1C hypertension rats were treated with lercanidipine 2.5 mg/kg/day (or vehicle) starting three weeks after hypertension was induced. Systolic blood pressure was monitored weekly. After five weeks of treatment, aortic rings were isolated to assess endothelium-dependent and independent relaxations. Quantitative morphometry of structural changes in the aortic wall were studied in hematoxylin/eosin sections. Aortic MMP-2 levels were determined by gelatin zymography. Aortic MMP-2/tissue inhibitor of metalloproteinases (TIMP)-2 mRNA levels were determined by quantitative real-time RT-PCR. Plasma thiobarbituric acid reactive substances concentrations were determined using a fluorometric method. Lercanidipine attenuated 2K-1C hypertension (224 12 versus 183 11 mm Hg in 2K-1C rats and 2K-1C + Lercandipine rats, respectively; P < 0.01) and prevented the reduction in endothelium-dependent vasorelaxation found in 2K-1C rats. Increased MMP-2 and Pro-MMP-2 levels were found in the aortas of 2K-1C rats (all P < 0.05). Lercandipine attenuated 2K-1C-induced increases in MMP-2 by more than 60% and blunted 2K-1C-induced increases in oxidative stress (both P < 0.001). While hypertension-induced significant aortic wall hypertrophy and approximately 9-fold increases in the ratio of MMP-2MMP-2 mRNA expression (both P < 0.05), lercandipine did not affect these changes. These results suggest that lercanidipine produces antihypertensive effects and reverses the endothelial dysfunction associated with 2K-1C hypertension, probably through mechanisms involving antioxidant effects leading to lower MMP-2 activation. (C) 2008 Elsevier B.V. All rights reserved.

Antioxidant treatment reduces matrix metalloproteinase-2-induced vascular changes in renovascular hypertension

Mounting evidence indicates that structural and functional vascular changes associated with two-kidney, one-clip (2K-1C) hypertension result, at least in part, from altered activity of matrix metalloproteinases (MMPs). Because MMPs are upregulated by increased formation of reactive oxygen species (ROS), we hypothesized that antioxidant approaches could attenuate the increases in MMP-2 expression/activity and the vascular dysfunction and remodeling associated with 2K-1C hypertension. Sham-operated or 2K-1C hypertensive rats were treated with tempol 18 mg/kg/day or apocyanin 25 mg/kg/day (or vehicle). Systolic blood pressure was monitored weekly. After 8 weeks of treatment, aortic rings were isolated to assess endothelium-dependent and -independent relaxation. Quantitative morphometry of structural changes in the aortic wall was studied in hematoxylin/eosin sections. Aortic and systemic ROS levels were measured using dihydroethidine and thiobarbituric acid-reactive substances, respectively. Aortic MMP-2 levels and activity were determined by gelatin and in situ zymography, fluorimetry, and immunohistochemistry. Tempol and apocyanin attenuated 2K-1C hypertension (181 +/- 20.8 and 192 +/- 17.6 mm Hg, respectively, versus 213 +/- 18 mm Hg in hypertensive controls; both p<0.05) and prevented the reduction in endothelium-dependent vasorelaxation found in 2K-1C rats. Tempol, but not apocyanin (p>0.05), prevented the vascular remodeling found in 2K-1C rats (all p<0.01). Tempol was more effective than apocyanin in attenuating hypertension-induced increases in oxidative stress (both p<0.05), MMP-2 levels, and MMP-2 activity in hypertensive rats (all p<0.05). Our results suggest that antioxidant approaches decrease MMP-2 upregulation and attenuate the vascular dysfunction and remodeling during 2K-1C hypertension. (C) 2009 Elsevier Inc. All rights reserved.

Photophysical studies and in vitro skin permeation/retention of Foscan (R)/nanoemulsion (NE) applicable to photodynamic therapy skin cancer treatment.

In this work we evaluated the photophysical and in vitro properties of Foscan (R), a second-generation photosensitizer drug (PS) widely used in systemic clinical protocols for cancer therapy based on Photodynamic Therapy (PDT). We employed biodegradable nanoemulsions (NE) as a colloidal vehicle of the oil/water (o/w) type focusing in topical administration of Foscan (R) and other photosensitizer drugs. This formulation was obtained and stabilized by the methodology described by Tabosa do Egito et al.,(30) based on the mixture of two phases: an aqueous solution and an organic medium consisting of nonionic surfactants and oil. The photodynamic potential of the drug incorporated into the NE was studied by steady-state and time-resolved spectroscopic techniques. We also analyzed the in vitro biological behavior carried out in mimetic biological environment protocols based on the animal model. After topical application in a skin animal model, we evaluated the Foscan (R)/NE diffusion flux into the skin layers (stratum corneum and epidermis + dermis) by classical procedures using Franz Diffusion cells. Our results showed that the photophysical properties of PS were maintained after its incorporation into the NE when compared with homogeneous organic medium. The in vitro assays enabled the determination of an adequate profile for the interaction of this system in the different skin layers, with an ideal time lag of 6 h after topical administration in the skin model. The Foscan (R) diffusion flux (J) was increased when this PS was incorporated into the NE, if compared with its flux in physiological medium. These parameters demonstrated that the NE can be potentially applied as a drug delivery system (DDS) for Foscan (R) in both in vitro and in vivo assays, as well as in future clinical applications involving topical skin cancer PDT.

In Vivo Evaluation of the Photoprotective Efficacy of O-1/W/O-2 Multiple Emulsions with Andiroba Oil (Carapa guianensis)

Stable multiple emulsions containing andiroba oil and sunscreen have been formulated. These were prepared using the two-step procedure. The formulations were characterized and their stability over the time was evaluated by centrifugation, macroscopic, and microscopic analyses, and rheological measurements. The photoprotective efficacy of the O/W and O1/W/O2 containing or not andiroba oil was evaluated by in vivo sun protection factor determination according to the FDA method. The formulations exhibited good stability during 30 days after preparation at different temperatures. These presented pseudoplastic flow behaviour and thixotropy. The increase of in vivo SPF value was not observed when andiroba oil was incorporated into emulsions containing ethylhexyl methoxycinnamate. These multiple emulsions can be utilized as an interesting topical vehicle.

O/W Nanoemulsion After 15 Years of Preparation: A Suitable Vehicle for Pharmaceutical and Cosmetic Applications

The application of nanoemulsions is due to have good stability, uniform spreading and enhance active penetration upon skin. Nanometer emulsions can be obtained by low-energy emulsification method. The required hydrophilic and lipophilic balance indicates the better balance of emulsifier for optimum system emulsification. Emulsion stability is evidently controlled for the properties of the adsorbed layer formed in the surface of its globules, know as potential zeta. The aim of this work was to evaluate the oil/water nanoemulsion of formulation obtained after 15 years of preparation. The results suggested that the nanoemulsion have performed stability for many years.

Low level and sub-chronic exposure to methylmercury induces hypertension in rats: nitric oxide depletion and oxidative damage as possible mechanisms

Increased risk of hypertension after methylmercury (MeHg) exposure has been suggested. However, the underlying mechanisms are not well explored. In this paper, we have analyzed whether sub-chronic exposure to MeHg increases systolic blood pressure even at very low levels. In addition, we analyzed if the methylmercury-induced hypertension is associated with a decreased plasmatic nitric oxide levels and with a dysregulation of the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), as well as the levels of MDA and glutathione. For this study, Wistar rats were treated with methylmercury chloride (100 mu g/kg per day) or vehicle. Total treatment time was 100 days. Malondialdehyde (MDA) and circulating NOx levels and superoxide dismutase (SOD) and catalase (CAT) activities were determined in plasma, whereas glutathione levels were determined in erythrocytes. Our results show that long-term treatment at a low level of MeHg affected systolic blood pressure, increasing and reducing the levels of plasmatic MDA and NOx, respectively. However, the activity of SOD did not decrease in the MeHg exposed group when compared to the control. We found a negative correlation between plasmatic nitrite/nitrate (NOx) levels and systolic blood pressure (r = -0.67; P = 0.001), and a positive correlation between MDA and systolic blood pressure (r = 0.61; P = 0.03), thus suggesting increased inhibition of NO formation with the increase of hypertension. In conclusion, long-term exposure to a low dose of MeHg increases the systolic pressure and is associated, at least in part, with increased production of ROS as judged by increased production of malondialdehyde and depressed NO availability.

Curcumin could prevent methemoglobinemia induced by dapsone in rats

The curcumin`s effect given orally by gavage in single- or multiple-dose regimens on methemoglobinemia induced by dapsone (DDS) was investigated in male Wistar rats. In the single-dose regimen, groups of 10 rats received either vehicle alone, or curcumin at 0.1, 1.0, 10, or 30 mg/kg body weight (bw), or curcumin at 0.02, 0.1, 1, 10, or 30 mg/kg bw plus DDS at 40 mg/kg bw, intraperitoneally (i.p.), 2 hours after. In the multiple-dose regimen, groups of 10 rats received either vehicle alone, or curcumin at 0.1, 1.0, 10, or 30 mg/kg bw for 5 days, with or without DDS (40 mg/kg bw, i.p.) 2 hours after on the fifth day. In both regimens, further groups of 10 rats were given DDS alone (positive controls) or normal saline (negative controls) i.p. Single-dose treatment with curcumin at 0.02 and 0.1 mg/kg bw significantly reduced DDS-induced methemoglobin formation, while the higher doses showed a pro-oxidant effect, significantly increasing DDS-induced methemoglobinemia. In the multiple-dose regimen, treatment with curcumin at 0.1 mg/kg bw significantly reduced DDS-induced methemoglobin formation, but the higher doses were without significant effect compared to DDS alone. It is concluded that curcumin at low doses mitigates methemoglobinemia induced by dapsone in rats, both in single- and multiple-dose regimens. (C) 2011 Elsevier Ltd. All rights reserved.

Dexamethasone Effects in the Strongyloides venezuelensis Infection in A Murine Model

The aim of this study was to investigate the immunomodulatory effects of glucocorticoids on the immune response to Strongyloides venezuelensis in mice. Balb/c mice were infected with S. venezuelensis and treated with Dexamethasone (Dexa) or vehicle. Dexa treatment increased circulating blood neutrophil numbers and inhibited eosinophil and mononuclear cell accumulation in the blood, bronchoalveolar, and peritoneal fluid compared with control animals. Moreover, Dexa decreased tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-3 (IL-3), IL-4, IL-5, IL-10, and IL-12 production in the lungs and circulating immunoglobulin G1. (IgG1), IgG2a, and IgE antibody levels while increasing the overall parasite burden in the feces and intestine. Dexa treatment enhanced the fertility of female nematodes relative to untreated and infected mice. In summary, the alterations in the immune response induced by Dexa resulted in a blunted, aberrant immune response associated with increased parasite burden. This phenomenon is similar to that observed in S. stercoralis-infected humans who are taking immunosuppressive or antiinflammatory drugs, including corticosteroids.

Metal embryotoxicity from urban particles in Sao Paulo city: An experimental study in chicken embryos

Chicken eggs were inoculated with suspensions of ambient air particles (<= 10 mu m, PM(10)) from Sao Paulo city in 3, 0.3 or 0.03 mu g doses on one of the four early days of embryo development. On the eleventh day of development alterations were observed on embryos inoculated with PM(10) 3 mu g on the third day. Particles analysis showed high content of metals. Hence, embryos were also inoculated with PM(10) (3 mu g) combined with metal chelating EDTA. PM(10) (3 mu g) embryos presented underdevelopment (stage 29.44 +/- 11.4) compared to vehicle and positive controls (stage 36.44 +/- 0.51 Saline and stage 31.20 +/- 9.7 Cyclophosphamide, p <= 0.05); higher (47%) mortality rate (23% Saline and 42% Cyclophosphamide) and low (68%) viability (100% Saline and 70% Cyclophosphamide, p = 0.04). Effects were attenuated when embryos received PM(10) + EDTA (stage 33.63 +/- 0.94, 18.9% mortality rate and 82% viability). PM(10) from Sao Paulo city is embryotoxic and metal may be implicated in the toxic mechanism. (C) 2010 Elsevier Inc. All rights reserved.

Chronic Treatment with Quercetin does not Inhibit Angiotensin-Converting Enzyme In Vivo or In Vitro

The precise mechanisms explaining the anti-hypertensive effects produced by quercetin are not fully known. Here, we tested the hypothesis that chronic quercetin treatment inhibits the angiotensin-converting enzyme (ACE). We examined whether quercetin treatment for 14 days reduces in vivo responses to angiotensin I or enhances the responses to bradykinin in anaesthetised rats. We measured the changes in systemic arterial pressure induced by angiotensin I in doses of 0.03-10 mu g/kg, by angiotensin II in doses of 0.01-3 mu g/kg, and to bradykinin in doses of 0.03-10 mu g/kg in anaesthetised rats pre-treated with vehicle (controls), or daily quercetin 10 mg/kg intraperitoneally for 14 days, or a single i.v. dose of captopril 2 mg/kg. Plasma ACE activity was determined by a fluorometric method. Plasma quercetin concentrations were assessed by high performance liquid chromatography. Quercetin treatment induced no significant changes in the hypertensive responses to angiotensin I and angiotensin II, as well in the hypotensive responses to bradykinin (all p > 0.05). Conversely, as expected, a single dose of captopril inhibited the hypertensive responses to angiotensin I and potentiated the bradykinin responses (all p < 0.01), while no change was found in the vascular responses to angiotensin II (all p > 0.05). In addition, although we found significant amounts of quercetin in plasma samples (mean = 206 ng/mL), no significant differences were found in plasma ACE activity in rats treated with quercetin compared with those found in the control group (50 +/- 6 his-leu nmol/min/mL and 40 +/- 7 his-leu nmol/min/mL, respectively; p > 0.05). These findings provide strong evidence indicating that quercetin does not inhibit ACE in vivo or in vitro and indicate that other mechanisms are probably involved in the antihypertensive and protective cardiovascular effects associated with quercetin.

Aerodynamic Drag Reduction for Satellites in Low Earth Orbit

Stalker (AIAA Paper 87-0403) has suggested that, by ejecting molecules directly upstream from the entire face of a satellite, it is possible to reduce the drag on a satellite in low-Earth orbit and hence maintain orbit with a total fuel mass (for forward ejection and conventional reaction rockets) less than the typical mass requirements of conventional rockets. An analytical analysis is presented here, as well as Monte Carlo simulations. These indicate that to reduce the overall drag on the satellite significantly, collisions between the freestream and ejected molecules must occur at least two satellite diameters upstream. This can be achieved if the molecules are ejected far upstream from the satellite’s surface through a sting that projects forward from the satellite. Using some estimates of what would be feasible sting arrangements, we find that the drag on the satellite can be reduced to such an extent that the satellite’s orbit can be maintained with a total fuel mass of less than 60% of that required for reaction rockets alone. Upstream ejection is effective in reducing the drag for freestream Knudsen numbers less than approximately 250, but not otherwise.

Bcl-2 in endothelial cells is increased by vitamin E and alpha-lipoic acid supplementation but not exercise training

Atherosclerotic plaque contains apoptotic endothelial cells with oxidative stress implicated in this process. Vitamin E and a-lipoic acid are a potent antioxidant combination with the potential to prevent endothelial apoptosis. Regular exercise is known to increase myocardial protection, however, little research has investigated the effects of exercise on the endothelium. The purpose of these studies was to investigate the effects of antioxidant supplementation and/or exercise training on proteins that regulate apoptosis in endothelial cells. Male rats received a control or antioxidant-supplemented diet (vitamin E and alpha-lipoic acid) and were assigned to sedentary or exercise-trained groups for 14 weeks. Left ventricular endothelial cells (LVECs) were isolated and levels of the anti-apoptotic protein Bcl-2 and the pro-apoptotic protein Bax were measured. Antioxidant supplementation caused a fourfold increase in Bcl-2 (P < 0.05) with no change in Bax (P > 0.05). Bcl-2:Bax was increased sixfold with antioxidant supplementation compared to non-supplemented animals (P < 0.05). Exercise training had no significant effect on Bcl-2, Bax or Bcl-2:Bax either alone or combined with antioxidant supplementation (P > 0.05) compared to non-supplemented animals. However, Bax was significantly lower (P < 0.05) in the supplemented trained group compared to non-supplemented trained animals. Cultured bovine endothelial cells incubated for 24 h with vitamin E and/or a-lipoic acid showed the combination of the two antioxidants increased Bcl-2 to a greater extent than cells incubated with the vehicle alone. In summary, vitamin E and a-lipoic acid increase endothelial cell Bcl-2, which may provide increased protection against apoptosis. (c) 2005 Elsevier Ltd. All rights reserved

Non-Equilibrium Reaction Rates in the Macroscopic Chemistry Method for DSMC Calculations

The Direct Simulation Monte Carlo (DSMC) method is used to simulate the flow of rarefied gases. In the Macroscopic Chemistry Method (MCM) for DSMC, chemical reaction rates calculated from local macroscopic flow properties are enforced in each cell. Unlike the standard total collision energy (TCE) chemistry model for DSMC, the new method is not restricted to an Arrhenius form of the reaction rate coefficient, nor is it restricted to a collision cross-section which yields a simple power-law viscosity. For reaction rates of interest in aerospace applications, chemically reacting collisions are generally infrequent events and, as such, local equilibrium conditions are established before a significant number of chemical reactions occur. Hence, the reaction rates which have been used in MCM have been calculated from the reaction rate data which are expected to be correct only for conditions of thermal equilibrium. Here we consider artificially high reaction rates so that the fraction of reacting collisions is not small and propose a simple method of estimating the rates of chemical reactions which can be used in the Macroscopic Chemistry Method in both equilibrium and non-equilibrium conditions. Two tests are presented: (1) The dissociation rates under conditions of thermal non-equilibrium are determined from a zero-dimensional Monte-Carlo sampling procedure which simulates ‘intra-modal’ non-equilibrium; that is, equilibrium distributions in each of the translational, rotational and vibrational modes but with different temperatures for each mode; (2) The 2-D hypersonic flow of molecular oxygen over a vertical plate at Mach 30 is calculated. In both cases the new method produces results in close agreement with those given by the standard TCE model in the same highly nonequilibrium conditions. We conclude that the general method of estimating the non-equilibrium reaction rate is a simple means by which information contained within non-equilibrium distribution functions predicted by the DSMC method can be included in the Macroscopic Chemistry Method.

Hypothalamic dopamine D1 receptors are involved in the stimulation of prolactin secretion by high environmental temperature in the female sheep

Recent evidence suggests that dopamine, acting via its D1 receptors, may function as a neurotransmitter in intrahypothalamic pathways involved in the stimulation of prolactin secretion. Functional dopamine D1 receptors are present in the ventromedial hypothalamic nucleus (VMH) and we hypothesized that they might be part of a prolactin-stimulatory pathway activated by stress. We tested this hypothesis in a series of experiments on sheep involving two different forms of stressors, audiovisual (barking dog) and high environmental temperature. We attempted to block the stimulation of prolactin secretion by infusion into the VMH of an antagonist specific for the D1 receptor. Ovariectomised, oestradiol-implanted merino ewes were surgically implanted with bilateral guide tubes directed at the VMH. After a 180 min pretreatment period, the ewes either were or were not exposed to a stressor (30 min of barking dog or 120 min at 35 degrees C, 65% relative humidity). D1 receptor antagonist, SCH23390 or vehicle (0.9% saline) was infused into the VMH (1.7 mu l/h, 120 nmol/h) for 60 min prior to and during the stressor period. Blood was sampled every 15 min via jugular cannulae and the plasma was assayed for prolactin, cortisol and growth hormone (GH). Both stressors significantly increased prolactin concentrations over control levels. SCH23390 infusion significantly attenuated the prolactin response to high environmental temperature, but had no effect on the prolactin response to audiovisual stress. Cortisol concentrations were significantly increased by audiovisual stress only and were not affected by SCH23390, GH concentrations were not changed by either stressor or infusion. Drug infusion alone did not affect the concentration of the hormones. The data suggest that the VMH D1 receptors are involved in a prolactin stimulatory pathway in response to high environmental temperature. The inability of the D1 antagonist to affect the response to the barking dog indicates that this pathway is stress-specific, implying that there is more than one mechanism or pathway involved in the prolactin response to different stressors.

Efficacy of zeta-cypermethrin as pour-on or spray formulations for the control of buffalo fly (Haematobia irritans exigua) in cattle

Objective To determine the efficacy of zeta-cypermethrin in controlling buffalo fly (Haematobia irritans exigua). Design Five field trials in northern and central Queensland. Procedure Zeta-cypermethrin pour-on at 2.5 mg/kg, spray at 62.5 ppm, deltamethrin pour-on and pour-on vehicle were applied to groups of 20 cattle. Buffalo fly counts were conducted three times before treatment and 3, 7, 14, 21, 28 and 35 days after treatment. Results In central Queensland where synthetic pyrethroid resistance in buffalo fly populations was rare, 2.5 mg/kg of zeta-cypermethrin pour-on gave good control of buffalo fly for 4 weeks and was better than a deltamethrin product. A zeta-cypermethrin spray used at 62.5 ppm gave 14 days control. In far-north Queensland where resistance to synthetic pyrethroids and heavy rain was common, the maximum period of efficacy of zeta-cypermethrin pour-on was reduced to 2 weeks. Conclusion In areas where there is low resistance to synthetic pyrethroids among buffalo flies, zeta-cypermethrin pour-on can be expected to give good control for 4 weeks.