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Leiva A, Aguiló A, Fajó-Pascual M, Moreno L, Martín MC, Garcia EM, Duro RE, Serra F, Dagosto P, Iglesias-Iglesias AA, Company RM, Yañez A, Llobera J. Efficacy of a brief multifactorial adherence-based intervention in reducing blood pressure: a randomized clinical trial. Patient Prefer Adherence 2014; 8:1683-90. [PMID: 25525344 PMCID: PMC4266385 DOI: 10.2147/ppa.s66927] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Lowering blood pressure (BP) by antihypertensive (AHT) drugs reduces the risks of cardiovascular events, stroke, and total mortality. However, poor adherence to AHT medications reduces their effectiveness and increases the risk of adverse events. OBJECTIVE To evaluate the effectiveness of a multifactorial adherence-based intervention in a primary care setting in lowering BP. METHODS/DESIGN Multicenter parallel randomized controlled trial. Thirty two nurses in 28 primary care centers of three Spanish regions. Patients aged 18-80 years, taking AHT drugs with uncontrolled BP (n=221) were randomized to a control group (usual care) or a multifactorial adherence-based intervention including nurse-led motivational interviews, pill reminders, family support, BP self-recording, and simplification of the dosing regimen by a pharmacist. MAIN OUTCOME MEASURES The primary outcome was 12-month blinded measure of systolic BP (mean of three measurements). The secondary outcomes were 12-month diastolic BP and proportion of patients with adequately controlled BP. RESULTS One hundred and fourteen patients were allocated to the intervention group and 109 to the control group. At 12 months, 212 (89%) participants completed the study. The systolic BP in the intervention group was 151.3 versus 153.7 in the control group (P=0.294). The diastolic BP did not differ between groups (83.4 versus 83.6). Of the patients in the control group, 9.2% achieved BP control versus a 15.8% in the intervention group. The relative risk for achieving BP control was 1.72 (95% confidence interval: 0.83-3.56). CONCLUSION A multifactorial intervention based on improving adherence in patients with uncontrolled hypertension failed to find evidence of effectiveness in lowering systolic BP. TRIAL REGISTRATION ISRCTN21229328.
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Fonseca M, Fleitas G, Tamborero G, Benejam M, Leiva A. Estilos de vida de los médicos de atención primaria: percepción e implicaciones sobre la prevención cardiovascular. Semergen 2013; 39:421-32. [DOI: 10.1016/j.semerg.2013.01.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/08/2013] [Accepted: 01/17/2013] [Indexed: 11/29/2022]
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Pardo F, Arroyo P, Salomón C, Westermeier F, Salsoso R, Sáez T, Guzmán-Gutiérrez E, Leiva A, Sobrevia L. Role of equilibrative adenosine transporters and adenosine receptors as modulators of the human placental endothelium in gestational diabetes mellitus. Placenta 2013; 34:1121-7. [PMID: 24119573 DOI: 10.1016/j.placenta.2013.09.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/27/2013] [Accepted: 09/13/2013] [Indexed: 01/13/2023]
Abstract
Gestational diabetes mellitus (GDM) is a diseases that alters human placenta macro and microvascular reactivity as a result of endothelial dysfunction. The human placenta is a highly vascularized organ which lacks innervation, so blood flux is governed by locally released vasoactive molecules, including the endogenous nucleoside adenosine and the free radical nitric oxide (NO). Altered adenosine metabolism and uptake by the endothelium leads to increased NO synthesis which then turns-off the expression of genes coding for a family of nucleoside membrane transporters belonging to equilibrative nucleoside transporters, particularly isoforms 1 (hENT1) and 2 (hENT2). This mechanism leads to increased extracellular adenosine and, as a consequence, activation of adenosine receptors to further sustain a tonic activation of NO synthesis. This is a phenomenon that seems operative in the placental macro and microvascular endothelium in GDM. We here summarize the findings available in the literature regarding these mechanisms in the human feto-placental circulation. This phenomenon is altered in the feto-placental vasculature, which could be crucial for understanding GDM deleterious effects in fetal growth and development.
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Yañez A, Leiva A, Gorreto L, Tejera E, Torrent M. El instituto, la familia y el tabaquismo en adolescentes. Adicciones 2013. [DOI: 10.20882/adicciones.53] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Esteva M, Leiva A, Ramos M, Pita-Fernández S, González-Luján L, Casamitjana M, Sánchez MA, Pértega-Díaz S, Ruiz A, Gonzalez-Santamaría P, Martín-Rabadán M, Costa-Alcaraz AM, Espí A, Macià F, Segura JM, Lafita S, Arnal-Monreal F, Amengual I, Boscá-Watts MM, Hospital A, Manzano H, Magallón R. Factors related with symptom duration until diagnosis and treatment of symptomatic colorectal cancer. BMC Cancer 2013; 13:87. [PMID: 23432789 PMCID: PMC3598975 DOI: 10.1186/1471-2407-13-87] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Accepted: 02/18/2013] [Indexed: 12/13/2022] Open
Abstract
Background Colorectal cancer (CRC) survival depends mostly on stage at the time of diagnosis. However, symptom duration at diagnosis or treatment have also been considered as predictors of stage and survival. This study was designed to: 1) establish the distinct time-symptom duration intervals; 2) identify factors associated with symptom duration until diagnosis and treatment. Methods This is a cross-sectional study of all incident cases of symptomatic CRC during 2006–2009 (795 incident cases) in 5 Spanish regions. Data were obtained from patients’ interviews and reviews of primary care and hospital clinical records. Measurements: CRC symptoms, symptom perception, trust in the general practitioner (GP), primary care and hospital examinations/visits before diagnosis, type of referral and tumor characteristics at diagnosis. Symptom Diagnosis Interval (SDI) was calculated as time from first CRC symptoms to date of diagnosis. Symptom Treatment Interval (STI) was defined as time from first CRC symptoms until start of treatment. Nonparametric tests were used to compare SDI and STI according to different variables. Results Symptom to diagnosis interval for CRC was 128 days and symptom treatment interval was 155. No statistically significant differences were observed between colon and rectum cancers. Women experienced longer intervals than men. Symptom presentation such as vomiting or abdominal pain and the presence of obstruction led to shorter diagnostic or treatment intervals. Time elapsed was also shorter in those patients that perceived their first symptom/s as serious, disclosed it to their acquaintances, contacted emergencies services or had trust in their GPs. Primary care and hospital doctor examinations and investigations appeared to be related to time elapsed to diagnosis or treatment. Conclusions Results show that gender, symptom perception and help-seeking behaviour are the main patient factors related to interval duration. Health service performance also has a very important role in symptom to diagnosis and treatment interval. If time to diagnosis is to be reduced, interventions and guidelines must be developed to ensure appropriate examination and diagnosis during both primary and hospital care.
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Yañez A, Leiva A, Gorreto L, Estela A, Tejera E, Torrent M. School, family and adolescent smoking. Adicciones 2013; 25:253-259. [PMID: 23880838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The socio-cultural environment is an important factor involved with the onset of smoking during adolescence. Initiation of cigarette smoking occurs almost exclusively during this stage. In this context we aimed to analyze the association of school and family factors with adolescent smoking by a cross-sectional study of 16 secondary schools randomly selected from the Balearic Islands involved 3673 students and 530 teachers. The prevalence of regular smoking (at least one cigarette per week) was 4.8% among first year students, 11.6% among second year students, 14.1% among third year students, 20.9% among fourth year students and 22% among teachers. Among first and second year students, there were independent associations between regular smoking and adolescents' perception of being allowed to smoke at home, belonging to a single parent family, poor relationship with parents, poor academic performance, lack of interest in studies and teachers' perception of smoking in the presence of pupils. Among third and fourth year students, there were independent associations between regular smoking and poor relationship with parents, adolescents' perception of being allowed to smoke at home, poor academic performance, lack of control over student misbehavior and the school attended. The school policies and practices affect student related health behavior regarding smoking, independent of individual and family factors.
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Cox JF, Allende R, Lara E, Leiva A, Díaz T, Dorado J, Saravia F. Follicular dynamics, interval to ovulation and fertility after AI in short-term progesterone and PGF2α oestrous synchronization protocol in sheep. Reprod Domest Anim 2012; 47:946-51. [PMID: 22471421 DOI: 10.1111/j.1439-0531.2012.01996.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The study was aimed to assess the influence that short-term progesterone treatments have on follicular dynamics, oestrus and ovulation in sheep. The treatment was tested thereafter in a field trial to assess its fertility after AI with fresh semen. In a first experiment, 12 ewes without CL were grouped to receive a new (n = 6) or used CIDR (n = 6) for 7 days and blood samples were obtained to follow plasma progesterone profiles. In a second experiment, 39 cycling ewes were synchronized by a 7-day P4+PGF2α protocol using a new (n = 20) or a 7-day used CIDR (n = 19). Half of both groups received 400 IU eCG and half remained untreated as controls. Ultrasound ovarian examination and oestrous detection were used to compare follicular dynamics, oestrus and ovulation in both groups. In a third experiment, 288 ewes in 3 farms were synchronized by the short-term P4+PGF2α+eCG protocol and ewes were AI with fresh semen 24 h after oestrous detection. Lambing performance was used to test the fertility of the treatment. In Experiment 1, ewes with new inserts presented higher P4 concentration than ewes with used inserts throughout the sampling period (p < 0.05) and exhibited a P4 peak at days 1-2 of the treatment that was not observed in ewes with used inserts. In Experiment 2, ewes treated with new and used inserts show similar ovarian and behavioral traits (p > 0.10). However, ewes treated with eCG show shorter interval to oestrus (p = 0.004) and tend to have larger mature CL (p = 0.06). In Experiment 3, oestrous presentation and lambing performance after AI with fresh semen was considered normal compared to published results. Results suggest that the oestrous synchronization protocol based on P4+PGF2α allows little control of follicular dynamics without compromising fertility after AI with fresh semen provided that eCG is added at the end of the treatment.
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Gargallo L, Becerra N, Sandoval C, Pitsikalis M, Hadjichristidis N, Leiva A, Radic' D. Amphiphilic diblock copolymers containing poly(N-hexylisocyanate): Monolayer behavior at the air-water interface. J Appl Polym Sci 2011. [DOI: 10.1002/app.34078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Vicens C, Socias I, Mateu C, Leiva A, Bejarano F, Sempere E, Basora J, Palop V, Mengual M, Beltran JL, Aragonès E, Lera G, Folch S, Piñol JL, Esteva M, Roca M, Arenas A, Del Mar Sureda M, Campoamor F, Fiol F. Comparative efficacy of two primary care interventions to assist withdrawal from long term benzodiazepine use: a protocol for a clustered, randomized clinical trial. BMC FAMILY PRACTICE 2011; 12:23. [PMID: 21507257 PMCID: PMC3105938 DOI: 10.1186/1471-2296-12-23] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 04/20/2011] [Indexed: 11/21/2022]
Abstract
Background Although benzodiazepines are effective, long-term use is not recommended because of potential adverse effects; the risks of tolerance and dependence; and an increased risk of hip fractures, motor vehicle accidents, and memory impairment. The estimated prevalence of long-term benzodiazepine use in the general population is about 2,2 to 2,6%, is higher in women and increases steadily with age. Interventions performed by General Practitioners may help patients to discontinue long-term benzodiazepine use. We have designed a trial to evaluate the effectiveness and safety of two brief general practitioner-provided interventions, based on gradual dose reduction, and will compare the effectiveness of these interventions with that of routine clinical practice. Methods/Design In a three-arm cluster randomized controlled trial, general practitioners will be randomly allocated to: a) a group in which the first patient visit will feature a structured interview, followed by visits every 2-3 weeks to the end of dose reduction; b) a group in which the first patient visit will feature a structured interview plus delivery of written instructions to self-reduce benzodiazepine dose, or c) routine care. Using a computerized pharmaceutical prescription database, 495 patients, aged 18-80 years, taking benzodiazepine for at least 6 months, will be recruited in primary care health districts of three regions of Spain (the Balearic Islands, Catalonia, and Valencia). The primary outcome will be benzodiazepine use at 12 months. The secondary outcomes will include measurements of anxiety and depression symptoms, benzodiazepine dependence, quality of sleep, and alcohol consumption. Discussion Although some interventions have been shown to be effective in reducing benzodiazepine consumption by long-term users, the clinical relevance of such interventions is limited by their complexity. This randomized trial will compare the effectiveness and safety of two complex stepped care interventions with that of routine care in a study with sufficient statistical power to detect clinically relevant differences. Trial Registration Current Controlled Trials: ISRCTN13024375
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Sobrevia L, Abarzúa F, Nien JK, Salomón C, Westermeier F, Puebla C, Cifuentes F, Guzmán-Gutiérrez E, Leiva A, Casanello P. Review: Differential placental macrovascular and microvascular endothelial dysfunction in gestational diabetes. Placenta 2011; 32 Suppl 2:S159-64. [PMID: 21215450 DOI: 10.1016/j.placenta.2010.12.011] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2010] [Revised: 12/09/2010] [Accepted: 12/09/2010] [Indexed: 10/18/2022]
Abstract
Human endothelial dysfunction is a common feature in many diseases of pregnancy, such as gestational diabetes (GD). Metabolic changes include abnormal synthesis of nitric oxide (NO) and abnormal membrane transport of l-arginine and adenosine in primary cultures of human umbilical vein (HUVEC, macrovascular) and placental microvillus (hPMEC, microvascular) endothelial cells. These alterations are associated with modifications in the expression and activity of endothelial (eNOS) and inducible (iNOS) NO synthases, respectively, an effect that is maintained at least up to passage 5 in culture. HUVEC and hPMEC exhibit expression and activity of the human cationic amino acid transporter 1 (hCAT-1), equilibrative nucleoside transporters 1 (hENT1) and hENT2, as well as the corresponding SLC7A1, SLC29A1 and SLC29A2 gene promoter activities. Altered gene expression results from increased NO level, protein kinase C, mitogen-activated protein kinases, and hCHOP-C/EBPα transcription factor activation. Reduced ENT-mediated adenosine transport in GD is associated with stimulation of the l-arginine/NO pathway, and mainly due to reduced expression and activity of hENT1. In addition, hENT2 activity seems able to restore the reduced adenosine transport in GD. Additionally, insulin exerts a differential modulation of endothelial cells from macrocirculation compared with microcirculation, possibly due to expression of different insulin receptor isoforms. It is suggested that a common functional characteristic leading to changes in the bioavailability of adenosine and metabolism of l-arginine is evidenced by human fetal micro and macrovascular endothelium in GD.
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Leiva A, Fajó M, Escriche L, Audera FJ, López S, Martín MC, González R, Tamborero G, García EM, Duro R, Orueta R, Serra F, D'agosto P P, Miralles J, Lorente P, Llobera J, Iglesias AA, Fernández R, Colom MM, Buades AM, Moreno L, Vidal C. Efficacy of a brief multifactorial adherence-based intervention on reducing the blood pressure of patients with poor adherence: protocol for a randomized clinical trial. BMC Cardiovasc Disord 2010; 10:44. [PMID: 20868531 PMCID: PMC2955598 DOI: 10.1186/1471-2261-10-44] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 09/27/2010] [Indexed: 11/11/2022] Open
Abstract
Background Lowering of blood pressure by antihypertensive drugs reduces the risks of cardiovascular events, stroke, and total mortality. However, poor adherence to antihypertensive medications reduces their effectiveness and increases the risk of adverse events. In terms of relative risk reduction, an improvement in medication adherence could be as effective as the development of a new drug. Methods/Design The proposed randomized controlled trial will include patients with a low adherence to medication and uncontrolled blood pressure. The intervention group will receive a multifactorial intervention during the first, third, and ninth months, to improve adherence. This intervention will include motivational interviews, pill reminders, family support, blood pressure self-recording, and simplification of the dosing regimen. Measurement The primary outcome is systolic blood pressure. The secondary outcomes are diastolic blood pressure, proportion of patients with adequately controlled blood pressure, and total cost. Discussion The trial will evaluate the impact of a multifactorial adherence intervention in routine clinical practice. Ethical approval was given by the Ethical Committee on Human Research of Balearic islands, Spain (approval number IB 969/08 PI). Trial registration Current controlled trials ISRCTN21229328
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Tagle LH, Terraza CA, Leiva A, Yazigi N, Lopez L. Poly(imide-amide)s and poly(imide-ester)s obtained from N,N′-(4,4′-Me,R-diphthaloyl)-bis-glycine acid dichloride (R =Me, Et): Synthesis, characterization, and thermal studies. J Appl Polym Sci 2010. [DOI: 10.1002/app.32007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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88
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Tagle LH, Terraza CA, Leiva A, Alvarez P. Polyesters based on two silarylene or germarylene moieties: Synthesis under phase-transfer conditions. J Appl Polym Sci 2009. [DOI: 10.1002/app.30645] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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89
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Gargallo L, Vargas D, Becerra N, Sandoval C, Saldias C, Leiva A, Radić D. Supramolecular Structures, Organization and Surface Behavior at Interfaces. ACTA ACUST UNITED AC 2009. [DOI: 10.1002/masy.200950410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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90
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Tagle LH, Terraza CA, Leiva A, Devilat F. Synthesis, characterization, and thermal studies of polyamides and polyimides containing two silarylene units in the main chain. J Appl Polym Sci 2008. [DOI: 10.1002/app.28830] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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91
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Esteva M, Ripoll J, Leiva A, Sánchez-Contador C, Collado F. Determinants of non attendance to mammography program in a region with high voluntary health insurance coverage. BMC Public Health 2008; 8:387. [PMID: 19014522 PMCID: PMC2596126 DOI: 10.1186/1471-2458-8-387] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Accepted: 11/13/2008] [Indexed: 11/24/2022] Open
Abstract
Background High participation rates are needed to ensure that breast cancer screening programs effectively reduce mortality. We identified the determinants of non-participation in a public breast cancer screening program. Methods In this case-control study, 274 women aged 50 to 64 years included in a population-based mammography screening program were personally interviewed. Socio-demographic characteristics, health beliefs, health service utilization, insurance coverage, prior mammography and other preventive activities were examined. Results Of the 192 cases and 194 controls contacted, 101 and 173, respectively, were subsequently interviewed. Factors related to non-participation in the breast cancer screening program included higher education (odds ratio [OR] = 5.28; 95% confidence interval [CI95%] = 1.57–17.68), annual dental checks-ups (OR = 1.81; CI95%1.08–3.03), prior mammography at a private health center (OR = 7.27; CI95% 3.97–13.32), gynecologist recommendation of mammography (OR = 2.2; CI95%1.3–3.8), number of visits to a gynecologist (median visits by cases = 1.2, versus controls = 0.92, P = 0.001), and supplemental private insurance (OR = 5.62; CI95% = 3.28–9.6). Among women who had not received a prior mammogram or who had done so at a public center, perceived barriers were the main factors related to non-participation. Among women who had previously received mammograms at a private center, supplemental private health insurance also influenced non-participation. Benign breast symptoms increased the likelihood of participation. Conclusion Our data indicate that factors related to the type of insurance coverage (such as prior mammography at a private health center and supplemental private insurance) influenced non-participation in the screening program.
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Terraza CA, Tagle LH, Leiva A, Poblete L, Concha FJ. Poly(urethanes) containing silarylene and/or germarylene units. J Appl Polym Sci 2008. [DOI: 10.1002/app.28170] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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93
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Gargallo´ L, Leiva A, Alegría L, Miranda B, González A, Radic D. Interfacial Properties of Poly(N‐Vinyl‐2‐Pyrrolidone) at the Air/Water Interface. J MACROMOL SCI B 2007. [DOI: 10.1081/mb-200033255] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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94
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Gargallo L, Miranda B, Leiva A, González A, Sandoval C, Radic´ D, Tagle LH. Poly(ester)s Containing Germanium and Silicon in the Main Chain. 1. Langmuir Monolayer Characterization. J MACROMOL SCI B 2007. [DOI: 10.1080/00222340500407988] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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95
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Basha KA, Balakrishnan T, Urzúa M, Leiva A, Gargallo L, Radic D. Copolymers of Phenoxyethyl Methacrylate with N‐Vinyl‐2‐pyrrolidone: Synthesis, Characterization and Reactivity Ratios. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2007. [DOI: 10.1080/10601320601044641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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96
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Tagle LH, Terraza CA, Leiva A, Valenzuela P. Poly(amides) and poly(imides) containing silicon and germanium in the main chain: Synthesis, characterization and thermal studies. J Appl Polym Sci 2006. [DOI: 10.1002/app.24454] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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97
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Leiva A, Gargallo L, González A, Radić D. Poly(tetrahydropyranyl-2-methyl methacrylate): Comparative study in solution and at the air/water interface. J Colloid Interface Sci 2005; 292:397-402. [PMID: 16083897 DOI: 10.1016/j.jcis.2005.05.089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 05/27/2005] [Accepted: 05/31/2005] [Indexed: 11/17/2022]
Abstract
In this work a comparative study of different molecular-weight fractions of the amphiphilic polymer poly(tetrahydropyranyl-2-methyl methacrylate) (PTHPMM) in solution and at the air/water interface is reported. The synthesis of the polymer was carried out in solution by radical polymerization. The polymer was fractionated and five fractions were studied in solution and at the air/water interface. The weight-average molecular weight M(w), the second virial coefficient A(2), and the radius of gyration R(g) were determined in toluene by static light scattering. Intrinsic viscosities [eta] of the polymer fractions in three solvents were obtained. The Kuhn-Mark-Houwink-Sakurada relationships were established. The Langmuir isotherms for different polymer fractions were obtained at the air/water interface by monolayer compression at constant temperature. The overlap surface concentrations were determined, and from these results the radius of gyration in two dimensions was calculated. The thermodynamic power of the toluene and the air/water interface for PTHPMM were estimated from the empirical relationship between the radius of gyration in two and three dimensions and the weight-average molecular weight.
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Pladevall M, Brotons C, Gabriel R, Sobrino J, Leiva A, Soler J, Cirujano FJ, Canal V, Alvarez E, De la Iglesia N, Luis Alvarez I, Deig E, Novella B. 023: The COM99 Study Results: A Cluster-Randomized Trial of an Intervention to Improve Adherence to Antihypertensive Drugs Among Patients at High Cardiovascular Risk. Am J Epidemiol 2005. [DOI: 10.1093/aje/161.supplement_1.s6b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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99
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Leiva A, Gargallo L, Radić D. Interfacial Properties of Poly(Caprolactone) and Derivatives. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2004. [DOI: 10.1081/ma-120030926] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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100
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Leiva A, Gargallo L, González A, Radic̀ D. Poly(itaconates) monolayers behavior at the air/water interface. Study at different surface concentration. Eur Polym J 2004. [DOI: 10.1016/j.eurpolymj.2004.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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