David López - Academia.edu (original) (raw)

Papers by David López

The Journal of pharmacology and experimental therapeutics, Jan 11, 2015

Membrane lipid therapy is a novel approach to rationally design or discover therapeutic molecules... more Membrane lipid therapy is a novel approach to rationally design or discover therapeutic molecules that target membrane lipids. This strategy has been used to design synthetic fatty acid analogues that are currently under study in clinical trials for the treatment of cancer. In this context, and with the aim of controlling tumor cell growth, we have designed and synthesized a hydroxylated analogue of triolein, hydroxytriolein (HTO). Both triolein and HTO regulate the biophysical properties of model membranes and they inhibit the growth of non-small lung cancer cell lines in vitro. The molecular mechanism underlying the anti-proliferative effect of HTO involves regulation of the lipid membrane structure, PKCα and ERK activation, the production of reactive oxygen species (ROS) and autophagy. In vivo studies on a mouse model of non-small cell lung cancer showed that HTO but not triolein impairs tumor growth, which could be associated with the relative resistance of HTO to enzymatic degr...

PLOS ONE, 2015

Caffeine is consumed by more than 85% of adults and little is known about its role on erectile dy... more Caffeine is consumed by more than 85% of adults and little is known about its role on erectile dysfunction (ED) in population-based studies. We investigated the association of caffeine intake and caffeinated beverages with ED, and whether these associations vary among comorbidities for ED. Data were analyzed for 3724 men (≥20 years old) who participated in the National Health and Nutrition Examination Survey (NHANES). ED was assessed by a single question during a self-paced, computer-assisted self-interview. We analyzed 24-h dietary recall data to estimate caffeine intake (mg/day). Multivariable logistic regression analyses using appropriate sampling weights were conducted. We found that men in the 3rd (85-170 mg/day) and 4th (171-303 mg/day) quintiles of caffeine intake were less likely to report ED compared to men in the lowest 1st quintile (0-7 mg/day) [OR: 0.58; 95% CI, 0.37-0.89; and OR: 0.61; 95% CI, 0.38-0.97, respectively], but no evidence for a trend. Similarly, among overweight/obese and hypertensive men, there was an inverse association between higher quintiles of caffeine intake and ED compared to men in the lowest 1st quintile, P≤0.05 for each quintile. However, only among men without diabetes we found a similar inverse association (Ptrend = 0.01). Caffeine intake reduced the odds of prevalent ED, especially an intake equivalent to approximately 2-3 daily cups of coffee (170-375 mg/day). This reduction was also observed among overweight/obese and hypertensive, but not among diabetic men. Yet, these associations are warranted to be investigated in prospective studies.

American journal of men's health, Jan 18, 2015

The Prostate Outreach Project (POP) provided free prostate cancer (PCa) education and early detec... more The Prostate Outreach Project (POP) provided free prostate cancer (PCa) education and early detection to medically underserved communities. POP recruited participants in medically underserved communities. PCa education and detection events occurred in POP locations (static) or natural gathering places (mobile) within the community. PCa education was delivered by video and evaluated using a questionnaire. Screening consisted of serum prostate-specific antigen and digital rectal examination. A navigated follow-up strategy was utilized to provide medical care for participants with abnormal screening examinations (ASE). POP recruited 4,420 men, 62.8% (2,667) were African American (AA). Most participants had a high school education and no prior screening. Fifty-four percent (2,159) were uninsured and 41% (1,811) had no access to a physician. PCa knowledge increased following the educational video. Prostate-specific antigen levels were elevated in 9.8% (436), while 6.9% (233) had an abnor...

Internal corrosion and circumferential cracking due to a corrosion fatigue process are some of th... more Internal corrosion and circumferential cracking due to a corrosion fatigue process are some of the most common failure causes of waterwall boiler tubes. The case study reported in this paper considers the failure of waterwall tubes of a small subcritical refinery boiler due to a combination of both processes. Circumferential cracking is reported in supercritical boilers with the characteristic felature of transgranular cracks. Intergranular corrosion fatigue cracks were present as a result of high temperature, which resulted from the presence of internal corrosion and formation of heavy deposits. While internal corrosion played a key role in the failure mechanism, the root cause of the failure is considered to be related to the generation of reducing atmospheres and high thermal flux due to flame impingement.

THIS PAPER EXAMINES REBAR STEELS WITH A MINIMUM YIELD STRENGTH OF 590 MPA. THE MECHANICAL PROPERT... more THIS PAPER EXAMINES REBAR STEELS WITH A MINIMUM YIELD STRENGTH OF 590 MPA. THE MECHANICAL PROPERTIES DETERMINED EXPERIMENTALLY PROVE THAT REBARS MICROALLOYED WITH NIOBIUM AND VANADIUM ARE CAPABLE OF REINFORCING CONCRETE CONSTRUCTION. TERMS: M--(U), MEXICO, ENGLISH, 1MN STEEL, ELONGATION, GRAIN SIZE, INCLUSIONS, MANGANESE ADDITION, NIOBIUM ADDITION, OPTICAL MICROSCOPY, SEM, STRESS STRAIN DATA, TEM, TENSILE YIELD STRENGTH, ULTIMATE TENSILE STRENGTH, VANADIUM ADDITION, CONTINUOUS CASTING, HOT ROLLING, MICROALLOYING, IRON ALLOYS, MECHANICAL PROPERTIES, MICROSTRUCTURE;

347-H stainless steel is widely used in superheater or reheater tubes of power boilers, where typ... more 347-H stainless steel is widely used in superheater or reheater tubes of power boilers, where typical operating temperatures are in the range of 550 oC -650 oC. During operation, microstructures are subject to changes because of the diffusion of alloy elements, giving place to phenomena like phase precipitation and phase growth. Carbide and sigma phase are the main precipitating phases at this temperature range. Grain refinement has not been reported in superheater or reheater tube steels. Evidence of grain refinement was detected during a previous study on the causes of a high corrosion rate of a 347H superheater tube which was operating in a 350 MW oil-fired boiler. The grain size reduction was detected in the hotter zones of the tube. Grain size measurements in specimens of three tubes were carried out confirming the presence of a grain reduction process in the hotter zones of 347H superheater tubes. TEM analysis revealed a polygonal structure of dislocations decorated by precipitation of fine M2306 carbides. It was concluded that a recrystallization process took place induced by high temperature on a deformed structure generated during the tube manufacture process.

We analyze and compare the static and dynamic properties of alkoxycyanobiphenyl (9OCB). This comp... more We analyze and compare the static and dynamic properties of alkoxycyanobiphenyl (9OCB). This compound exhibits an I-N-SmA phase sequence. After confining into Anopore structures several phenomena can be seen: Both phase transitions change in their nature, Cp peaks becoming lower, broader and shifted down in temperatures. A possible first-to-second order transition could be determined for the N-SmA. There developes a

In this paper, a modified Steffensen's type iterative scheme for the numerical solution of a syst... more In this paper, a modified Steffensen's type iterative scheme for the numerical solution of a system of nonlinear equations is studied. Two convergence theorems are presented. The numerical solution of boundary-value problems by the multiple shooting method using the proposed iterative scheme is analyzed.

Celestial Mechanics & Dynamical Astronomy, 1999

Recently, Gonzlez, Martn and Farto have developed new numerical methods (RKGM methods) of Runge–K... more Recently, Gonzlez, Martn and Farto have developed new numerical methods (RKGM methods) of Runge–Kutta type and fixed step size for the numerical integration of perturbed oscillators. Moreover, it seems natural to study the behaviour of these new methods for the accurate integration of orbital problems after the application of linearizing transformation, such us KS or BF due to the fact

Journal of Physical Chemistry B, 2003

ABSTRACT The complete stable phase diagram of the two-component system (heptyloxy)cyanobiphenyl (... more ABSTRACT The complete stable phase diagram of the two-component system (heptyloxy)cyanobiphenyl (7OCB) + (octyloxy)cyanobiphenyl (8OCB) was determined by means of modulated differential scanning calorimetry (MDSC), optical microscopy, and X-ray diffraction measurements. It was experimentally established that the 7OCB + 8OCB two-component system exhibits a monotropic reentrant nematic behavior. A complete quantitative thermodynamic analysis, through Oonk's equal G analysis, was performed, including the calculation of the monotropic reentrant behavior and a discussion of the stable melting phase diagram. Moreover, the specific-heat critical exponents (α), through second-order SmA to N transition, was obtained. If these α-values, together with those corresponding to other systems sharing cyanobiphenyl (nCB and nOCB) compounds, are plotted against the normalized nematic ranges, a common and uniform crossover trend is found. This behavior allows one to predict, in a simple way, the order of the SmA to N transition.

Journal of Physical Chemistry B, 2005

The two-component system octyloxycyanobiphenyl (8OCB) + decyloxycyanobiphenil (10OCB) has been st... more The two-component system octyloxycyanobiphenyl (8OCB) + decyloxycyanobiphenil (10OCB) has been studied by means of modulated differential scanning calorimetry as well as optical microscopy. The general trends of the phase diagram are similar to the two-component system octylcyanobiphenyl (8CB) + decylcyanobiphenil (10CB), previously published. Evidence for the existence of a TCP have been reported, the molar composition being about 0.33 of 10OCB. Additionally, the smectic mesophase of the 8OCB + 10OCB mixtures has been unmistakably characterized through optical measurements as smectic A for the whole composition range.

Scripta Metallurgica, 1989

Radiología (English Edition), 2010

To report our experience in percutaneous radiofrequency ablation of renal tumors, emphasizing tec... more To report our experience in percutaneous radiofrequency ablation of renal tumors, emphasizing technical aspects and indications and analyzing our results. We retrospectively analyzed 20 tumors in 13 patients (10 with a single kidney, 2 who had refused surgical treatment, and 1 with severe comorbidities). All procedures were carried out using the radiofrequency interstitial tumor ablation (RITA) technique under general anesthesia and CT guidance. All patients underwent follow-up CT examination with and without intravenous contrast administration; the absence of enhancement was considered complete necrosis. The mean size of the tumors was 2.8 cm. Complete necrosis was achieved in 17 tumors (85%); complete necrosis was achieved in 100% of the exophytic tumors and in 50% of the tumors with mixed growth after 14 months&amp;#39; follow-up. Complete ablation was achieved in 15 of the 16 tumors measuring &amp;lt; or =3.5 cm. In 9 of the 10 patients with a single kidney (four of whom had more than one tumor), renal function remained normal after the procedure; the other patient developed hydronephrosis after a urinary tract lesion and died. The patient who died also developed a subcapsular liver lesion that did not require transfusion when another tumor was treated transhepatically. In experienced hands and with careful selection of patients (exophytic tumors &amp;lt; or =3.5 cm), radiofrequency ablation of renal tumors can achieve excellent oncologic results with minimal morbidity and mortality.

Revista Española de Cirugía Ortopédica y Traumatología, 2011

Radial nerve palsy after humeral shaft fractures can be secondary to manipulation. Incorrect diag... more Radial nerve palsy after humeral shaft fractures can be secondary to manipulation. Incorrect diagnosis of soft tissue entrapment can lead to repetitive manipulation, putting the radial nerve at risk. We present a case of humeral shaft fracture with soft tissue entrapment and secondary nerve palsy that was successfully managed with open reduction and percutaneous fixation. We discuss the correct management

Corrosion Reviews, 1996

ABSTRACT Ash deposits, fuel treatment and fuel specification are considered between the most impo... more ABSTRACT Ash deposits, fuel treatment and fuel specification are considered between the most important technical factors that require specific consideration for economical use of heavy fuel oils in gas turbines or combined cycles. Ash deposits built in the hot gas path of gas turbines can cause severe erosion and corrosion of blades an vanes besides of fouling associated to the Mg Base Aditive used in order to inhibite vanadium and significant contaminant in residual fuel oils. Erosion corrosion and ash deposits constitute the central problem affecting turbine reliability and service life when using low quality fuel oils. The aim of this paper is to show how these detrimental processes are interrelated using heavy high sulfur fuel oils.

Case Studies in Structural Engineering, 2014

The project "Brick-topia" was based on a combination of the latest structural analysis and form-f... more The project "Brick-topia" was based on a combination of the latest structural analysis and form-finding computational tools with traditional, cheap and effective construction techniques. It is the result of innovation to fight against budget and time. The initial budget was 3,000 euros and only seven weeks was the time to look for sponsors, design the pavilion, plan the construction phases and build it.

Lecture Notes in Computer Science, 2009

We propose a novel approach for on-line signature verification based on building HMM user models ... more We propose a novel approach for on-line signature verification based on building HMM user models by adapting an ergodic Universal Background Model (UBM). State initialization of this UBM is driven by a dynamic signature feature. This approach inherits the properties of the GMM-UBM mechanism, such as minimizing overfitting due to scarcity of user training data and allowing a world-model type of likelihood normalization. This system is experimentally compared to a baseline state-of-the-art HMM-based online signature verification system using two different databases: the well known MCYT-100 corpus and a subset of the signature part of the BIOSECURE-DS2 corpus. The HMM-UBM approach obtains promising results, outperforming the baseline HMM-based system on all the experiments.

Biophysical journal, Jan 2, 2012

We propose that accumulated membrane bending energy elicits a neutral sphingomyelinase (SMase) ac... more We propose that accumulated membrane bending energy elicits a neutral sphingomyelinase (SMase) activity in human erythrocytes. Membrane bending was achieved by osmotic or chemical processes, and SMase activity was assessed by quantitative thin-layer chromatography, high-performance liquid chromatography, and electrospray ionization-mass spectrometry. The activity induced by hypotonic stress in erythrocyte membranes had the pH dependence, ion dependence, and inhibitor sensitivity of mammalian neutral SMases. The activity caused a decrease in SM contents, with a minimum at 6 min after onset of the hypotonic conditions, and then the SM contents were recovered. We also elicited SMase activity by adding lysophosphatidylcholine externally or by generating it with phospholipase A(2). The same effect was observed upon addition of chlorpromazine or sodium deoxycholate at concentrations below the critical micellar concentration, and even under hypertonic conditions. A unifying factor of the v...

Biochimica et biophysica acta, 2014

Alzheimer's disease (AD) is a neurodegenerative pathology with relevant unmet therapeutic nee... more Alzheimer's disease (AD) is a neurodegenerative pathology with relevant unmet therapeutic needs. Both natural aging and AD have been associated with a significant decline in the omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA), and accordingly, administration of DHA has been proposed as a possible treatment for this pathology. However, recent clinical trials in mild-to-moderately affected patients have been inconclusive regarding the real efficacy of DHA in halting this disease. Here, we show that the novel hydroxyl-derivative of DHA (2-hydroxydocosahexaenoic acid - OHDHA) has a strong therapeutic potential to treat AD. We demonstrate that OHDHA administration increases DHA levels in the brain of a transgenic mouse model of AD (5xFAD), as well as those of phosphatidylethanolamine (PE) species that carry long polyunsaturated fatty acids (PUFAs). In 5xFAD mice, administration of OHDHA induced lipid modifications that were paralleled with a reduction in amyloid-β (Αβ) ...