Rahimian R. Sex differences in mesenteric endothelial function of streptozotocin-induced diabetic rats: a shift in the relative importance of EDRFs. Am J Physiol Heart Circ Physiol 303: H1183-H1198, 2012. First published September 14, 2012 doi:10.1152 doi:10. /ajpheart.00327.2012 studies suggest that diabetes affects male and female vascular beds differently. However, the mechanisms underlying the interaction of sex and diabetes remain to be investigated. This study investigates whether there are 1) sex differences in the development of abnormal vascular responses and 2) changes in the relative contributions of endothelium-derived relaxing factors in modulating vascular reactivity of mesenteric arteries taken from streptozotocin (STZ)-induced diabetic rats at early and intermediate stages of the disease (1 and 8 wk, respectively). We also investigated the mesenteric expression of the mRNAs for endothelial nitric oxide (NO) synthase (eNOS) and NADPH oxidase (Nox) in STZ-induced diabetes in both sexes. Vascular responses to acetylcholine (ACh) in mesenteric arterial rings precontracted with phenylephrine were measured before and after pretreatment with indomethacin (cyclooxygenase inhibitor), N -nitro-L-arginine methyl ester (NOS inhibitor), or barium chloride (Kir blocker) plus ouabain (Na ϩ -K ϩ -ATPase inhibitor). We demonstrated that ACh-induced relaxations were significantly impaired in mesenteric arteries from both male and female diabetic rats at 1 and 8 wk. However, at 8 wk the extent of impairment was significantly greater in diabetic females than diabetic males. Our data also showed that in females, the levels of eNOS, Nox2, and Nox4 mRNA expression and the relative importance of NO to the regulation of vascular reactivity were substantially enhanced, whereas the importance of endotheliumderived hyperpolarizing factor (EDHF) was significantly reduced at both 1 and 8 wk after the induction of diabetes. This study reveals the predisposition of female rat mesenteric arteries to vascular injury after the induction of diabetes may be due to a shift away from a putative EDHF, initially the major vasodilatory factor, toward a greater reliance on NO.sex; diabetes; mesenteric arteries; nitric oxide; endothelium-derived hyperpolarizing factor CARDIOVASCULAR DISEASES (CVDs) are the major causes of morbidity and mortality in patients with diabetes mellitus. Several reports including our recent studies (30,31,36) suggest that hyperglycemia and diabetes affect male and female vascular beds differently. Clinically, premenopausal women have a lower incidence of CVDs compared with age-matched men. However, premenopausal women with diabetes not only lose this sex-based cardiovascular protection but also have a higher risk of CVDs than men (4,20,71). Nonetheless, there is insufficient evidence to establish the mechanism(s) underlying the loss of this female-specific cardiovascular protection in premenopausal patients with diabetes.Endothelial dysfunction is an early sign of diabetic vascular diseases. Endothelial dysfuncti...

The flipped classroom has been shown to have positive outcomes in learning. However, relatively little has been reported on the implementation of it in dental education. The purpose of this study was to evaluate the impact of the flipped classroom on predoctoral dental students’ learning. Two consecutive classes of dental students learned the physiology of the autonomic nervous system through the nonflipped (traditional lecture) or the flipped approach. Students’ learning was assessed with an identical quiz at the end of the module. The mean score in the flipped approach was higher than that in the nonflipped approach ( P < 0.01). Mean score on the content-based quiz questions in the flipped approach was higher than that in the nonflipped approach ( P < 0.05). Performance on case-based questions did not show a significant difference ( P = 0.12). Mean quiz performance of the lower 27% scorers in the flipped approach was higher than that in the nonflipped approach ( P < 0.05). Mean quiz performance of the upper 27% scorers showed an increase in the flipped approach as well ( P < 0.05), but to a less extent than that of the lower 27% scorers ( P < 0.01). The flipped approach also increased peer collaboration ( P < 0.01). In summary, the flipped classroom improved dental students’ performance on content-based questions in physiology. The flipped classroom narrowed the performance gap between the low- and high-performing dental students.

We describe the isolation and characterization of a new biosynthetic gene, MET2, from the methylotrophic yeast Pichia pastoris. The predicted product of PpMET2 is significantly similar to its Saccharomyces cerevisiae counterpart, ScMET2, which encodes homoserine-O-transacetylase. The ScMET2 was able to complement the P. pastoris met2 strain; however, the converse was not true. Expression vectors based on PpMET2 for the intracellular and secreted production of foreign proteins and corresponding auxotrophic strains were constructed and tested for use in heterologous expression. The expression vectors and corresponding strains provide greater flexibility when using P. pastoris for recombinant protein expression.

In an effort to develop pH-sensitive lipoplexes for efficient gene delivery, we report three novel cationic lipids containing a linear ortho ester linker that conjugates either the headgroup (Type I) or one hydrocarbon chain (Type II) with the rest of the lipid molecule. The cationic lipids carry either an iodide or a chloride counterion. Compared to our previously reported cyclic ortho ester linker, the linear ortho ester linker facilitated the construction of cationic liposomes and lipoplexes with different helper lipids. The chloride counterion not only facilitated the hydration of the lipid films during liposome construction, but also enhanced the hydrolysis of the ortho ester linker in the lipoplexes. After incubation at endosomal pH 5.5, the Type I lipoplexes aggregated and destabilized the endosome-mimicking model liposomes, but not the Type II lipoplexes. The helper lipids (DOPE or cholesterol) of the lipoplexes enhanced the pH-sensitivity of the Type I lipoplexes. In CV-1 cells (monkey kidney fibroblast), the Type I ortho ester-based lipoplexes, especially those with the chloride counterion, significantly improved the gene transfection efficiency, in some cases by more than 100 fold, compared to their pH-insensitive counterparts consisting of DOTAP. The gene transfection efficiency of the ortho ester-based lipoplexes was well correlated with their rate of aggregation and membrane destabilization in response to the endosomal pH 5.5.

Epidemiological data suggest that hyperglycemia abrogates the gender-based cardiovascular protection possibly associated with estrogens. This study was designed to investigate 1) whether rabbit aortic rings show gender differences in the development of abnormal endothelium-dependent vasodilation (EDV) under acute hyperglycemic conditions, 2) the potential role of PKC isoforms and superoxide (O2-) in acute hyperglycemia-induced vascular dysfunction, and 3) the effect of acute estrogen administration on hyperglycemia-induced endothelial dysfunction in male and female rabbits. EDV to ACh was determined before and after 3 h of treatment with high glucose (HG) in phenylephrine-precontracted aortic rings from male and female New Zealand White rabbits. Similar experiments were conducted in the presence of inhibitors of PKC-alpha, PKC-beta, and PKC-delta or an O2- scavenger. The effect of acute estrogen administration was evaluated in the presence and absence of HG. Finally, mRNA expression of PKC isoforms was measured by real-time PCR. We found that 1) 3 h of incubation with HG impairs EDV to a greater extent in female than male aorta, 2) inhibition of PKC-beta or O2- prevents HG-induced impairment of EDV in female aorta, 3) acute 17beta-estradiol aggravates HG-induced endothelial dysfunction in female, but not male, aorta, and 4) PKC-alpha and PKC-beta expression are significantly higher in female than male aorta. This study reveals the predisposition of female rabbit aorta to vascular injury under hyperglycemic conditions, possibly via activation of PKC-beta and O2- production. Furthermore, it suggests that, under hyperglycemic conditions, acute estrogen treatment is detrimental to endothelial function in female rabbits.

Recent evidence showed that 17 β-estradiol (E2) decreased cytokine-induced expression of cell adhesion molecules (CAM). Changes in intracellular Ca 2+ concentration ([Ca 2+ ] i ) has been shown to be associated with CAM expression in endothelial cells. Here, the effects of E 2 (1 μM, 24 h) on the expression of intracellular adhesion molecule-1 (ICAM-1) and [Ca 2+ ] i were investigated in a lipopolysaccharide (LPS) (100 ng/mL, 18 h)-stimulated human endothelial cell line, EA.hy926, using real-time PCR and spectrofluorometry, respectively. PCR analysis revealed a significant increase in ICAM-1 expression in calcium ionophore A23187 (1 nM)-or LPS-stimulated cells. Pretreatment of cells with E 2 significantly inhibited LPS-induced ICAM-1 mRNA expression. [Ca 2+ ] i was monitored in Fura-2 AM-loaded cells in the presence and absence of extracellular Ca 2+ with thapsigargin (TG, 1 μM), a sarco/endoplasmic reticulum ATPase inhibitor or ATP (100 μM). The extent of TG-or ATP-induced [Ca 2+ ] i increase was significantly higher in LPS-stimulated cells than in control cells. Pre-treatment of LPS-stimulated cells with E 2 limited the Ca 2+ response to the same level as in control cells. Furthermore, ICI 182,780, an estrogen receptor antagonist, attenuated the inhibitory actions of E 2 on ICAM-1 mRNA expression and Ca 2+ responses, suggesting that estrogen receptors mediate, at least in part, the effects of estrogen. These data suggest a potential underlying mechanism for the protective effect of E 2 against atherosclerosis.

Many reports in dental education showed that student learning improved with the flipped classroom method. However, there are few reports that describe how different subsets of students may benefit from the flipped classroom. In this study, we investigated how students’ preference for the flipped classroom impacted their learning outcome. We used a flipped classroom module on the physiology of the autonomic nervous system taught to year one Doctor of Dental Surgery students to test the hypothesis that students who favored the flipped classroom performed better on assessment quizzes. The module was composed of pre-class activity, out-of-class assignment, in-class discussion, and two in-class quizzes. Quiz 1 was given after students self-studied the foundational content online through the pre-class activity, and Quiz 2 was at the end of the module. Students filled out a survey to report learning experiences and preferences. Fewer students scored below 75% on Quiz 2 than on Quiz 1. Students’ self-evaluated understanding of content significantly improved after finishing the assignment and discussion compared to finishing the pre-class activity alone. Moreover, students who preferred to learn through the flipped classroom scored higher in Quiz 2. Students with higher overall grades in the course preferred the flipped classroom more than low performers. Our results indicated that students favoring the flipped classroom method spent more time on the assignment, understood the content better, and performed better on assessments than students who prefer traditional lectures.

Student presentations had been widely implemented across content areas, including health sciences education. However, due to various limitations, small-group student presentations in the classroom may not reach their full potential for student learning. To address challenges with presentations in the classroom, we redesigned the assignment by having students present and discuss online using VoiceThread, a cloud-based presentation and discussion tool. First-year students pursuing a Doctor of Dental Surgery degree were assigned into small groups to present physiology content and to discuss that content online. This assignment was similar to traditional student classroom presentations, with the exception that the entire assignment was conducted online. The primary purpose of this exploratory study was to investigate the impact of the online format on the discussion quality. Another purpose of the study was to examine students' perceptions of using VoiceThread for presenting and learning, as well as the online interactions between the presenter and audience. Students posted a higher number of questions and comments than required by the assignment. The questions from students were also higher level questions, and the answers to these questions were more thorough compared with what we had previously observed in classroom presentations. The survey results showed that students preferred using VoiceThread for presenting, learning from other presentations, and discussing presentation content over performing this process in the classroom. Preliminary findings suggested that having dental students make presentations and hold discussions online might help address the challenges of student presentations in the classroom.