Hydrophobically Modified Poly(acrylic acid) Using 3‐Pentadecylcyclohexylamine: Synthesis and Rheology

Summary: Hydrophobically modified poly(acrylic acid) was synthesized using 3‐pentadecylcyclohexylamine (3‐PDCA), which was in turn synthesized from 3‐pentadecylphenol, one of the components of cashew‐nut shell liquid (CNSL), a renewable resource material. ¹H NMR spectra confirmed the incorporation of 3‐PDCA onto PAA and a series of HMPs with three different molar concentrations, viz ? 3, 5 and 7 mol‐% of 3‐PDCA, were synthesized. An increase in viscosity with increasing hydrophobic content was observed by rheological measurements. The critical association concentrations were determined using an Ubbelohde viscometer and a controlled stress rheometer. The stability of HMPs towards temperature and shear was studied. Rheological measurements showed that there was a steady increase in viscosity with increase in hydrophobe content due to the formation of reversible networks. These polymers exhibited gel‐like behavior at low concentrations (≥2 wt.‐%) with an apparent yield stress (ca. 10 Pa) and showed shear thinning properties (non‐Newtonian). However, below a critical concentration, c [η], they showed Newtonian behavior.

η_sp of unmodified and modified PAA‐Na at various polymer concentrations.     

Acute hypervolemia does not improve arterial oxygenation in maximally exercising thoroughbred horses

Recently, it was reported that acute hypervolemia improves arterial oxygen tension in human athletes known to experience exercise-induced arterial hypoxemia. Since exercise-induced arterial hypoxemia is routinely observed in racehorses and is known to limit performance, we examined whether pre-exercise induction of acute hypervolemia would similarly benefit arterial oxygenation in maximally exercising thoroughbred horses. Two sets of experiments, namely, placebo [intravenous (IV) physiological saline] and acute hypervolemia (IV 7.2% NaCl, causing an 18.2% expansion of plasma volume) studies were carried out in random order on 13 healthy, exercise-trained thoroughbred horses, 7 days apart. An incremental exercise protocol leading to 120 s of galloping at 14 m s^–1 on a 3.5% uphill incline was used. Galloping at this workload elicited maximal heart rate and induced pulmonary hemorrhage in all horses in both treatments. In the placebo study, arterial oxygen tension decreased to 76.1 (2) mmHg (P<0.0001) at 30 s of maximal exertion, but further significant changes did not occur as exercise duration increased to 120 s [arterial oxygen tension 72.4 (2) mmHg]. A significant arterial hypoxemia also developed in galloping horses in the acute hypervolemia study [arterial oxygen tension at 30 and 120 s was 76.7 (1.7) and 71.9 (1.6) mmHg, respectively], but significant differences between treatments could not be demonstrated. In both treatments, a similar desaturation of arterial hemoglobin was also observed at 30 s of maximal exercise, which intensified with increasing exercise duration as hyperthermia, acidosis and hypercapnia intensified. Thus, acute expansion of plasma volume did not benefit arterial oxygenation in maximally exercising thoroughbred horses.     

肩关节注射治疗冻结肩的研究进展

冻结肩是导致肩关节疼痛及活动受限的常见疾病,肩关节注射是治疗冻结肩的最常用方法,包括糖皮质激素注射、液体扩张疗法、玻璃酸钠注射等。近年来肩关节注射治疗的研究较多,且有较多高质量随机对照研究,该文就糖皮质激素注射与其它治疗手段之间以及注射治疗的不同方式之间在疼痛缓解、活动度及功能改善等方面的疗效及安全性比较作一综述。     

Continuing Medical Education Activity in Echocardiography

Article Title: Transesophageal Echocardiographic Assessment of Pulmonary Veins and Left Atrium in Patients Undergoing Atrial Fibrillation Ablation (Echocardiography 2011;28:774)     

Impact of Student- Versus Instructor-Directed Case Discussions on Student Performance in a Pharmacotherapy Capstone Course

Objective. To evaluate the impact of incorporating student-directed (SD) vs instructor-directed (ID) active learning on student performance in a pharmacotherapy capstone course.Design. This 9-credit course was redesigned from exclusively ID case discussions to a format in which half were SD and half were ID. Student performance on evaluation questions derived from SD sessions was compared with that from ID sessions.Assessment. Overall, students (n=299) performed better on ID-session questions than on SD-session questions (78.7% vs 75.3%, correctly answered, respectively; p<0.001). For written evaluations, students performed better on ID-session questions than on SD-session questions (79.8% vs 73.9%, respectively; p<0.001). For verbal evaluations, students performed better on SD-session questions than on ID-session questions (79.5% vs 74.5%, respectively; p<0.001). After the course revision, student confidence regarding their ability to think critically, solve problems, make decisions, and pursue lifelong learning was high, and student and faculty feedback was positive.Conclusion. Student performance in a pharmacotherapy capstone course remained acceptable when a combination of SD and ID active learning was used, but the addition of SD learning did not translate to better performance on course evaluations.     

Exposure to childhood neglect and physical abuse and developmental trajectories of heavy episodic drinking from early adolescence into young adulthood

BackgroundAlthough the literature suggests that childhood maltreatment (CM) relates to adolescent heavy episodic drinking (HED), few studies have examined the long-term effects of CM on adolescent HED. This study is the first to examine associations between exposure to CM and trajectories of HED from adolescence to young adulthood for the US population.MethodsFour waves of data from the National Longitudinal Study of Adolescent Health were used. A total of 8503 adolescents followed from adolescence (7th–12th grades) into young adulthood (ages 24–32) were assessed on CM and past-year HED frequency. Using growth curve modeling, trajectories of adolescent HED were examined, with subtype, frequency, and severity of CM as the primary independent variables. All of our analyses controlled for common risk factors for adolescent HED, including demographics, parental and peer alcohol use, parental education and employment, family income, parent–child relationship, and adolescent depression.ResultsAfter controlling for potential risk factors, neglect and physical abuse, both individually and in conjunction, were associated with faster increases in HED during adolescence and persistently elevated HED over much of adolescence and young adulthood. The frequency of neglect and physical abuse, individually and in conjunction, was also associated with the trajectory of HED, such that additional instances of these types of maltreatment were associated with faster increases in HED during adolescence and higher rates of peak use during young adulthood.ConclusionChild neglect and physical abuse appear to have long-lasting adverse effects on HED beyond adolescence and throughout much of young adulthood.