Abstract:The postulated transition of Bis-Maltolato-OxoVanadium(IV) (BMOV) from its inactive trans-into its cis-aquo-BMOV isomeric form in solution was simulated by means of computational molecular modeling. The rotational barrier was calculated with DFT -B3LYP under a stepwise optimization protocol with STO-3G, 3-21G, 3-21G*, and 6-31G ab initio basis sets. Our computed results are consistent with reports on the putative molecular mechanism of BMOV triggering the insulin-like cellular response (insulin mimetic) as a potent inhibitor of the protein tyrosine phosphatase-1B (PTP-1B). Initially, trans-BMOV is present in its solid dosage form but in aqueous solution, and during oral administration, it is readily converted into a mixture of "open-type" and "closed-type" complexes of cis-aquo-BMOV under equilibrium conditions. However, in the same measure as the "closed-type" complex binds to the cytosolic PTP-1B, it disappears from solution, and the equilibrium shifts towards the "closed-type" species. In full accordance, the computed binding mode of cis-BMOV is energetically favored over sterically hindered trans-BMOV. In view of our earlier report on prodrug hypothesis of vanadium organic compounds the present results suggest that cis-BMOV is the bioactive species.
Scales are secondary deposits constituted by inorganic chemical compounds present in an anthropogenic system. They are generated by changes in the thermodynamic, kinetic and hydrodynamics conditions[1] when formation fluids are produced, or by mutual physicochemical incompatibility between production and injection fluids. Therefore, they can jeopardize the integrity, good condition and useful lifetime of geological formations, producing and injection wells, surface facilities and pipelines, increasing the industry operation costs.
Generally, these problems had been mitigated by using conventional technologies based on chemical compounds (polyphosphate, carboxylic compounds, among others), that generate environmental liabilities and represent high costs for the industry.
Recently, PDVSA Intevep, S.A. has developed a scale inhibitor product based on Aloe vera plant chemical component[2], that offers equal or in some cases better efficiency than conventional chemical treatments, on the same conditions of evaluation. In addition, it offers the potential benefits of a lower environmental impact.
In this study, the performance of this anti-scale polysaccharide-based product was evaluated in the laboratory, simulating oil and water transfer system from flow stations to tanks, producing wells with high water content and injection wells. After, the product was evaluated in pilot field tests in two wells during about 50 days each:Barinas´s production well with about 3200 BPD, 98% water and high scale tendency by Oddo-Thompson method at bottomhole.Monagas´s production well with about 2200 BPD, 74% water and high scale tendency by Stiff and Davis method at wellhead.
In both cases, the pilot field tests were successful. The scale inhibitor product developed was more efficient than commercial products used in those production wells.
Introduction - Systems description
Produced oil properties are geographically heterogeneous across Venezuela. Figure 1 shows the geographical location of the selected wells for the Aloe vera based scale inhibitor field test. Said field tests were carried out in systems with high scaling tendencies from their failure histories and Saturation Indexes (SI).
Use of alpha-adrenergic blockers for ureteral distal third stones has been shown to be effective for increasing the stone expulsion rate and even the number of stones passed, and for faster symptom relief.
Patients with Alzheimer's disease (AD) show high incidence of behavioral and psychological symptoms (BPS).The occurrence of BPS has a great impact on the patients and caregiver's quality of life, increases caregiver's burden, and in many cases precipitates admission of the patients to a geriatric center. On the other hand, the importance of the BPS is increasing because most of them are susceptible to being treated effectively, mainly thanks to the use of drug measures and behaviour modification techniques. This study describes the pathophysiological mechanisms of BPS in AD and its relationship with cognitive and functional impairment of patient and caregiver's burden and current therapies.
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