Value of Case-Based Learning within STEM Courses: Is It the Method or Is It the Student?

Undergraduate attrition from science, technology, engineering, and mathematics is well documented and generally intensifies during intermediate years of college. Many contributing factors exist; however, a mismatch between timing of certain pedagogical approaches, such as case-based learning, and the level of students' cognitive abilities plays a crucial role. Using cognitive load theory as a foundation, we examined relationships between case-based learning versus a traditional lecture and learning gains of undergraduates within an intermediate physiology course. We hypothesized instruction via a case study would provide greater learning benefits over a traditional lecture, with gains possibly tempered by student characteristics like academic preparation, as measured by ACT scores, and academic age, as measured by credit hours completed. Results were surprising. Case-based learning did not guarantee improved learning gains compared with a traditional lecture for all equally. Students with lower ACT scores or fewer credit hours completed had lower learning gains with a case study compared with a traditional lecture. As suggested by cognitive load theory, the amount of extraneous load potentially presented by case-based learning might overwhelm the cognitive abilities of inexperienced students.

Direct contact may affect the efficacy of stallion exposure in hastening the onset of cyclicity in anestrous mares.

Introducing males to seasonally anestrous females has been shown to increase LH concentrations and hasten the first ovulation in ewes and goat does. Investigation of this sociosexual phenomenon in mares has not been well studied. The objective of this study was to determine if direct or indirect exposure of anestrous mares to a stallion would result in a similar increase in LH and hasten the first ovulation. In late February, mares were stratified by parity and age and assigned randomly to three treatments (n = 7/treatment): (1) DXP (direct exposure; mares housed adjacent to stallion and allowed direct contact for 2 h for 3 d/wk by placing the stallion into a cage in the center of a tease pen); (2) IXP (indirect exposure; mares housed in an adjacent pen to the stallion but not allowed direct contact); and (3) CON (control; mares housed away from stallion and not allowed direct or indirect exposure). During the first, third, and fifth treatment days, blood was collected hourly for 8 h beginning just before treatment initiation for measurement of LH and prolactin (PRL) concentrations. Hormone concentrations were analyzed as repeated measures and time from the first day of treatment to ovulation was analyzed using one-way ANOVA. Interval from treatment initiation to first ovulation did not differ (P > 0.05) among treatments: 36.3 ± 6.7, 42.8 ± 4.2, and 48.3 ± 4.2 d for DXP, IXP, and CON, respectively. When comparing the mares based on social status within treatment and level of direct interaction with the stallion, socially dominant DXP mares ovulated sooner (P < 0.05) than socially subordinate DXP mares (23.8 ± 3.2 and 53.0 ± 6.8 d, respectively). Although LH concentrations did not differ (P > 0.05) among treatments, a significant (P < 0.05) day effect was detected with concentrations being greater on the fifth treatment day compared with the first and third days. Concentrations of PRL were greater (P < 0.05) in IXP compared with DXP and CON, regardless of treatment day. Regardless of treatment, PRL concentrations were greater (P < 0.05) on the third treatment day, compared with the first and fifth days. We conclude that exposure of anestrous mares to a stallion, whether direct or indirect, to anestrous mares failed to elicit the same effects that have been observed in short-day breeders. The effect of stallion exposure on the onset of cyclicity in anestrous mares may be dependent on the duration of direct contact.

Cognitive flexibility and undergraduate physiology students: increasing advanced knowledge acquisition within an ill-structured domain.

Cognitive flexibility is defined as the ability to assimilate previously learned information and concepts to generate novel solutions to new problems. This skill is crucial for success within ill-structured domains such as biology, physiology, and medicine, where many concepts are simultaneously required for understanding a complex problem, yet the problem consists of patterns or combinations of concepts that are not consistently used or needed across all examples. To succeed within ill-structured domains, a student must possess a certain level of cognitive flexibility: rigid thought processes and prepackaged informational retrieval schemes relying on rote memorization will not suffice. In this study, we assessed the cognitive flexibility of undergraduate physiology students using a validated instrument entitled Student's Approaches to Learning (SAL). The SAL evaluates how deeply and in what way information is processed, as well as the investment of time and mental energy that a student is willing to expend by measuring constructs such as elaboration and memorization. Our results indicate that students who rely primarily on memorization when learning new information have a smaller knowledge base about physiological concepts, as measured by a prior knowledge assessment and unit exams. However, students who rely primarily on elaboration when learning new information have a more well-developed knowledge base about physiological concepts, which is displayed by higher scores on a prior knowledge assessment and increased performance on unit exams. Thus students with increased elaboration skills possibly possess a higher level of cognitive flexibility and are more likely to succeed within ill-structured domains.

Comparison of polyglactin-910 and polydioxanone for closure of the linea alba following caudal ventral midline laparotomy in sheep.

This study compared incisional complications after ventral midline laparotomy using 2 absorbable suture materials for apposition of the linea alba in sheep. The linea alba of 93 yearling sheep was sutured by 3 veterinarians in a simple continuous pattern using either polyglactin 910 (PG910; group PG) or polydioxanone (PDS; group PD). A blinded observer assessed surgical sites at the time of suture removal. Multivariate logistic regression was used to assess the association between incisional complications and variables (suture material used, veterinarian, skin suture removal time). The odds of incisional complications did not vary significantly with the type of suture material used (P = 0.11), veterinarian (P = 0.61) or skin suture removal time (P = 0.36). Most incisional complications were cutaneous suture sinus formation. Either PG910 or PDS may be used for linea alba closure in sheep.

Comparison de l'utilisation du polyglactin 910 et du polydioxanone pour suturer la ligne blanche lors de laparotomies ventrales médianes caudales chez la brebis. Cette étude compare les complications incisionnelles suite à une laparotomie ventrale médiane en utilisant 2 fils de sutures pour l'apposition de la ligne blanche chez la brebis. La ligne blanche de 93 brebis a été suturée par 3 vétérinaires en points simples continus avec du polyglactin 910 (PG910; groupe PG) ou du polydioxanone (PDS; groupe PD). Une observation à l'aveugle des sites chirurgicaux a été effectuée lors du retrait des points de suture. Une régression logistique multivariée a été utilisée pour déterminer l'association entre les complications incisionnelles et les variables (matériel de suture utilisé, vétérinaire et temps de retrait des sutures cutanées). Les chances de complications ne variaient pas selon le type de matériel de suture utilisé (P = 0,11), le vétérinaire (P = 0,61) ou la période de retrait des points cutanés (P = 0,36). La majorité des complications étaient des fistules associées aux sutures cutanées. Le PG910 ou le PDS peut être utilisé pour l'apposition de la ligne blanche chez la brebis.(Traduit par les auteurs).

A constructivist approach to e-text design for use in undergraduate physiology courses.

Electronic textbooks, or e-texts, will have an increasingly important role in college science courses within the next few years due to the rising costs of traditional texts and the increasing availability of software allowing instructors to create their own e-text. However, few guidelines exist in the literature to aid instructors in the development and design specifically of e-texts using sound learning theories; this is especially true for undergraduate physiology e-texts. In this article, we describe why constructivism is a very important educational theory for e-text design and how it may be applied in e-text development by instructors. We also provide examples of two undergraduate physiology e-texts that were designed in accordance with this educational theory but for learners of quite different backgrounds and prior knowledge levels.

Follicular expression of follicle stimulating hormone receptor variants in the ewe.

BACKGROUND: Several alternatively-spliced mRNA transcripts of the follicle stimulating hormone receptor (FSHR) have been identified in sheep, including FSHR-1 (G protein-coupled form), FSHR-2 (dominant negative form), and FSHR-3 (growth factor type-1 form). Our objective was to determine which of these variants is predominantly expressed in follicles collected from ewes at various times after estrus. METHODS: Suffolk-cross ewes (n = 8) were allowed to come into estrus naturally and were euthanized 24 (n = 3), 36 (n = 3), or 48 (n = 2) hours after the onset of estrus. All visible follicles were measured, aspirated and pooled according to follicular diameter: small (<= 2.0 mm), medium (2.1-4.0 mm), large (4.1-6.0 mm), and preovulatory (> = 6.1 mm). Aspirated cells were separated from follicular fluid by centrifugation. Total RNA was extracted from cell pellets and reverse transcribed. The resulting cDNA was subjected to qPCR, using primer sets designed to amplify each variant specifically. Gene expression was normalized to that of beta-actin within samples, and compared by analysis of variance with the level of significant differences set at p < .05. RESULTS: Relative expression of FSHR-3 exceeded that of both FSHR-1 and FSHR-2 in medium follicles, and tended to be higher in small follicles (p = .09) regardless of time after onset of estrus, and thus results from different time points were pooled. Expression of FSHR-3 was greater than that of FSHR-2 and luteinizing hormone receptor (LHR) in small and medium follicles. Expression of LHR was greatest in preovulatory follicles. CONCLUSIONS: These experiments show that in addition to the well characterized G protein-coupled form of the FSHR, alternatively spliced variants of the FSHR may participate in follicular dynamics during follicular waves of the sheep estrous cycle. Furthermore, these results indicate that an "alternatively" spliced form of the FSHR (FSHR-3) is the predominant form of the FSHR in the sheep.

The balance of proangiogenic and antiangiogenic VEGFA isoforms regulate follicle development.

Vascular endothelial growth factor A (VEGFA) has been extensively studied because of its role in follicular development and is a principal angiogenic factor essential for angiogenesis. Since vascularization of the theca layer increases as follicles progress in size through preantral and antral stages, VEGFA might influence follicle growth via the regulation of angiogenesis. However, VEGFA might also influence follicular development through nonangiogenic mechanisms, since its expression has been localized in nonvascular follicles and cells. Alternative mRNA splicing of eight exons from the VEGFA gene results in the formation of various VEGFA isoforms. Each isoform has unique properties and is identified by the number of amino acids within the mature protein. Proangiogenic isoforms (VEGFA_XXX) are encoded by exon 8a, whereas a sister set of isoforms (VEGFA_XXXB) with antiangiogenic properties is encoded by exon 8b. The antiangiogenic VEGFA_XXXB isoforms comprise the majority of VEGFA expressed in most tissues, whereas expression of the proangiogenic VEGFA isoforms is upregulated in tissues undergoing active angiogenesis. Although proangiogenic and antiangiogenic isoforms can now be distinguished from one another, many studies evaluating VEGFA in ovarian and follicular development up to now have not differentiated proangiogenic VEGFA from antiangiogenic VEGFA. Experiments from our laboratory indicate that proangiogenic VEGFA promotes follicle recruitment and early follicular development and antiangiogenic VEGFA inhibits these processes. The balance of proangiogenic versus antiangiogenic VEGFA isoforms is thus of importance during follicle development. Further studies are warranted to elucidate the way that this balance regulates follicular formation and progression.

Inhibition of vascular endothelial growth factor receptor signal transduction blocks follicle progression but does not necessarily disrupt vascular development in perinatal rat ovaries.

We hypothesized that vascular endothelial growth factor A (VEGFA) angiogenic isoforms and their receptors, FLT1 and KDR, regulate follicular progression in the perinatal rat ovary. Each VEGFA angiogenic isoform has unique functions (based on its exons) that affect diffusibility, cell migration, branching, and development of large vessels. The Vegfa angiogenic isoforms (Vegfa_120, Vegfa_164, and Vegfa_188) were detected in developing rat ovaries, and quantitative RT-PCR determined that Vegfa_120 and Vegfa_164 mRNA was more abundant after birth, while Vegfa_188 mRNA was highest at Embryonic Day 16. VEGFA and its receptors were localized to pregranulosa and granulosa cells of all follicle stages and to theca cells of advanced-stage follicles. To determine the role of VEGFA in developing ovaries, Postnatal Day 3/4 rat ovaries were cultured with 8 muM VEGFR-TKI, a tyrosine kinase inhibitor that blocks FLT1 and KDR. Ovaries treated with VEGFR-TKI had vascular development reduced by 94% (P < 0.0001), with more primordial follicles (stage 0), fewer early primary, transitional, and secondary follicles (stages 1, 3, and 4, respectively), and greater total follicle numbers compared with control ovaries (P < 0.005). V1, an inhibitor specific for KDR, was utilized to determine the effects of only KDR inhibition. Treatment with 30 muM V1 had no effect on vascular density; however, treated ovaries had fewer early primary, transitional, and secondary follicles and more primary follicles (stage 2) compared with control ovaries (P < 0.05). We conclude that VEGFA may be involved in primordial follicle activation and in follicle maturation and survival, which are regulated through vascular-dependent and vascular-independent mechanisms.