Simulation–Optimization Modeling: A Survey and Potential Application in Reservoir Systems Operation

This paper presents a survey of simulation and optimization modeling approaches used in reservoir systems operation problems. Optimization methods have been proved of much importance when used with simulation modeling and the two approaches when combined give the best results. The main objective of this review article is to discuss simulation, optimization and combined simulation– optimization modeling approach and to provide an overview of their applications reported in literature. In addition to classical optimization techniques, application and scope of computational intelligence techniques, such as, evolutionary computa- tions, fuzzy set theory and artificial neural networks, in reservoir system operation studies are reviewed. Conclusions and suggestive remarks based on this survey are outlined, which could be helpful for future research and for system managers to decide appropriate methodology for application to their systems

Autonomic and Renal Alterations in the Offspring of Sleep-Restricted Mothers During Late Pregnancy

OBJECTIVES: Considering that changes in the maternal environment may result in changes in progeny, the aim of this study was to investigate the influence of sleep restriction during the last week of pregnancy on renal function and autonomic responses in male descendants at an adult age. METHODS: After confirmation of pregnancy, female Wistar rats were randomly assigned to either a control or a sleep restriction group. The sleep-restricted rats were subjected to sleep restriction using the multiple platforms method for over 20 hours per day between the 14th and 20th day of pregnancy. After delivery, the litters were limited to 6 offspring that were designated as offspring from control and offspring from sleep-restricted mothers. Indirect measurements of systolic blood pressure (BPi), renal plasma flow, glomerular filtration rate, glomerular area and number of glomeruli per field were evaluated at three months of age. Direct measurements of cardiovascular function (heart rate and mean arterial pressure), cardiac sympathetic tone, cardiac parasympathetic tone, and baroreflex sensitivity were evaluated at four months of age. RESULTS: The sleep-restricted offspring presented increases in BPi, glomerular filtration rate and glomerular area compared with the control offspring. The sleep-restricted offspring also showed higher basal heart rate, increased mean arterial pressure, increased sympathetic cardiac tone, decreased parasympathetic cardiac tone and reduced baroreflex sensitivity. CONCLUSIONS: Our data suggest that reductions in sleep during the last week of pregnancy lead to alterations in cardiovascular autonomic regulation and renal morpho-functional changes in offspring, triggering increases in blood pressure

Mesenchymal stem cells (MSC) prevented the progression of renovascular hypertension, improved renal function and architecture

Renovascular hypertension induced by 2 Kidney-1 Clip (2K-1C) is a renin-angiotensin-system (RAS)-dependent model, leading to renal vascular rarefaction and renal failure. RAS inhibitors are not able to reduce arterial pressure (AP) and/or preserve the renal function, and thus, alternative therapies are needed. Three weeks after left renal artery occlusion, fluorescently tagged mesenchymal stem cells (MSC) (2×10(5) cells/animal) were injected weekly into the tail vein in 2K-1C hypertensive rats. Flow cytometry showed labeled MSC in the cortex and medulla of the clipped kidney. MSC prevented a further increase in the AP, significantly reduced proteinuria and decreased sympathetic hyperactivity in 2K-1C rats. Renal function parameters were unchanged, except for an increase in urinary volume observed in 2K-1C rats, which was not corrected by MSC. The treatment improved the morphology and decreased the fibrotic areas in the clipped kidney and also significantly reduced renal vascular rarefaction typical of 2K-1C model. Expression levels of IL-1β, TNF-α angiotensinogen, ACE, and Ang II receptor AT1 were elevated, whereas AT2 levels were decreased in the medulla of the clipped kidney. MSC normalized these expression levels. In conclusion, MSC therapy in the 2K-1C model (i) prevented the progressive increase of AP, (ii) improved renal morphology and microvascular rarefaction, (iii) reduced fibrosis, proteinuria and inflammatory cytokines, (iv) suppressed the intrarenal RAS, iv) decreased sympathetic hyperactivity in anesthetized animals and v) MSC were detected at the CNS suggesting that the cells crossed the blood-brain barrier. This therapy may be a promising strategy to treat renovascular hypertension and its renal consequences in the near future.Coordenação de Aperfeiçoamento de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Losartan Reduces Oxidative Stress Within the Rostral Ventrolateral Medulla of Rats With Renovascular Hypertension

Previous studies showed that the microinjection of antioxidants or the overexpression of superoxide dismutase within the rostral ventrolateral medulla (RVLM) reduces hypertension and sympathoexcitation in the 2-kidney, 1-clip (2K-1C) model. in this study, we hypothesized that angiotensin II (ANG II) type 1 receptor (AT(1)R) is involved in the oxidative stress within the RVLM and contributes to cardiovascular dysfunction in renovascular hypertension.Losartan (30mg/kg/day, oral gavage) was administered for 7 consecutive days by week 5 after implantation of the clip (gap width 0.2mm). Mean arterial pressure, baroreflex, and renal sympathetic nerve activity (rSNA) were evaluated. Superoxide production was evaluated by dihydroethidium (DHE) staining within the RVLM and within a control area. Systemic oxidative stress was characterized by measurement of thiobarbituric acid reactive substances (TBARS) and total glutathione (tGSH) in the blood.AT(1)R blockade significantly (P < 0.05) reduced hypertension by approximately 20% (n 11) and sympathoexcitation to the kidneys by approximately 41% (n 6) in the 2K-1C rats. Losartan treatment increased the baroreflex sensitivity of rSNA to pressor (67%) and depressor (140%) stimuli in the 2K-1C rats. AT(1)R blockade caused a significant (66%) reduction in DHE staining within the RVLM but not within the control area, reduced plasma TBARS (from 1.60.1 to 1.00.1 nmol/ml), and increased tGSH (from 3.40.4 to 5.20.3 mol/g Hb) in the 2K-1C group only.Our findings suggest that the beneficial effects of ANG II blockade in renovascular hypertension are partly due to preferential reduction of oxidative stress in the RVLM.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Dept Physiol, Div Cardiovasc, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biol Sci, Diadema, BrazilUniversidade Federal de São Paulo, Dept Physiol, Div Cardiovasc, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biol Sci, Diadema, BrazilWeb of Scienc

Crosstalk between the renal sympathetic nerve and intrarenal angiotensin II modulates proximal tubular sodium reabsorption

What is the topic of this review? the sympathetic control of renal sodium tubular reabsorption is dependent on activation of the intrarenal renin-angiotensin system and activation of the angiotensinII type1 (AT(1)) receptor by angiotensinII.What advances does it highlight? Despite the fact that the interaction between the sympathetic nervous system and angiotensinII regarding salt reabsorption is a well-known classical mechanism for the maintenance of extracellular volume homeostasis, the underlying molecular signalling is not clearly understood. It has been shown recently that renal nerve stimulation increases intrarenal angiotensinII and activates the AT(1) receptor, triggering a signalling cascade that leads to elevations of Na+-H+ exchanger isoform3-mediated tubular transport. in this short review, the crosstalk between intrarenal angiotensinII and renal nerve activity and its effect on sodium reabsorption is addressed.In this review, we address the importance of the interaction between the sympathetic nervous system and intrarenal renin-angiotensin system in modulating renal tubular handling of sodium and water. We have recently shown that increased Na+-H+ exchanger isoform3 (NHE3) activity induced by renal nerve stimulation (RNS) depends on the activation of the angiotensinII type1 (AT(1)) receptor by angiotensinII (AngII). Low-frequency RNS resulted in higher levels of intrarenal angiotensinogen and AngII independent of changes in blood pressure, the glomerular filtration rate and systemic angiotensinogen. AngiotensinII, via the AT(1) receptor, triggered an intracellular pathway activating NHE3 in the renal cortex, leading to antinatriuresis and antidiuresis. Pharmacological blockade of the AT(1) receptor with losartan prior to RNS abolished both the functional and the molecular responses, suggesting that intrarenal AngII acting via the AT(1) receptor is a major factor for NHE3-mediated sodium and water reabsorption induced by RNS.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, Dept Physiol, Div Cardiovasc Physiol, BR-04023060 São Paulo, SP, BrazilUniv São Paulo, Sch Med, Heart Inst InCor, São Paulo, SP, BrazilUniversidade Federal de São Paulo, Dept Physiol, Div Cardiovasc Physiol, BR-04023060 São Paulo, SP, BrazilWeb of Scienc