The impact of formative testing on study behaviour and study performance of (bio)medical students: a smartphone application intervention study.

BACKGROUND: Formative testing can increase knowledge retention but students often underuse available opportunities. Applying modern technology to make the formative tests more attractive for students could enhance the implementation of formative testing as a learning tool. This study aimed to determine whether formative testing using an internet-based application ("app") can positively affect study behaviour as well as study performance of (bio)medical students. METHODS: A formative testing app "Physiomics, to the next level" was introduced during a 4-week course to a large cohort (n = 461) of Dutch first year (bio)medical students of the Radboud University. The app invited students to complete 7 formative tests throughout the course. Each module was available for 3-4 days to stimulate the students to distribute their study activities throughout the 4-week course. RESULTS: 72% of the students used the app during the course. Study time significantly increased in intensive users (p < 0.001), while no changes were observed in moderate (p = 0.07) and non-users (p = 0.25). App-users obtained significantly higher grades during the final exam of the course (p < 0.05). Non-users more frequently failed their final exam (34%, OR 3.6, 95% CI: 2.0-6.4) compared to moderate users (19%) and intensive users (12%). Students with an average grade <6.5 during previous courses benefitted most from the app, as intensive (5.8 ± 0.9 / 36%) and moderate users (5.8 ± 0.9 / 33%) obtained higher grades and failed their exam less frequently compared to non-users (5.2 ± 1.1 / 61%). The app was also well appreciated by students; students scored the app with a grade of 7.3 ± 1.0 out of 10 and 59% of the students indicated that they would like the app to be implemented in future courses. CONCLUSIONS: A smartphone-based application of formative testing is an effective and attractive intervention to stimulate study behaviour and improve study performance in (bio) medical students

Flavaglines Stimulate Transient Receptor Potential Melastatin Type 6 (TRPM6) Channel Activity.

Magnesium (Mg2+) is essential for enzymatic activity, brain function and muscle contraction. Blood Mg2+ concentrations are tightly regulated between 0.7 and 1.1 mM by Mg2+ (re)absorption in kidney and intestine. The apical entry of Mg2+ in (re)absorbing epithelial cells is mediated by the transient receptor potential melastatin type 6 (TRPM6) ion channel. Here, flavaglines are described as a novel class of stimulatory compounds for TRPM6 activity. Flavaglines are a group of natural and synthetic compounds that target the ubiquitously expressed prohibitins and thereby affect cellular signaling. By whole-cell patch clamp analyses, it was demonstrated that nanomolar concentrations of flavaglines increases TRPM6 activity by ∼2 fold. The stimulatory effects were dependent on the presence of the alpha-kinase domain of TRPM6, but did not require its phosphotransferase activity. Interestingly, it was observed that two natural occurring TRPM6 mutants with impaired insulin-sensitivity, TRPM6-p.Val1393Ile and TRPM6-p.Lys1584Glu, are not sensitive to flavagline stimulation. In conclusion, we have identified flavaglines as potent activators of TRPM6 activity. Our results suggest that flavaglines stimulate TRPM6 via the insulin receptor signaling pathway

Functional TRPV6 channels are crucial for transepithelial Ca2+ absorption

Item does not contain fulltextTRPV6 is considered the primary protein responsible for transcellular Ca2+ absorption. In vitro studies demonstrate that a negatively charged amino acid (D) within the putative pore region of mouse TRPV6 (position 541) is critical for Ca2+ permeation of the channel. To elucidate the role of TRPV6 in transepithelial Ca2+ transport in vivo, we functionally analyzed a TRPV6D541A/D541A knockin mouse model. After weaning, mice were fed a regular (1% wt/wt) or Ca2+-deficient (0.02% wt/wt) diet and housed in metabolic cages. Blood was sampled for Ca2+ measurements, and the expression of Ca2+ transport proteins was analyzed in kidney and duodenum. Intestinal 45Ca2+ uptake was measured in vivo by an absorption assay. Challenging the mice with the Ca2+-deficient diet resulted in hypocalcemia in wild-type and TRPV6D541A/D541A mice. On a low-Ca2+ diet both mouse strains displayed increased expression of intestinal TRPV6, calbindin-D(9K), and renal TRPV5. TRPV6D541A/D541A mice showed significantly impaired intestinal Ca2+ uptake compared with wild-type mice, and duodenal TRPV5 expression was increased in TRPV6D541A/D541A mice. On a normal diet, serum Ca2+ concentrations normalized in both mouse strains. Under these conditions, intestinal Ca2+ uptake was similar, and the expression levels of renal and intestinal Ca2+ transport proteins were not affected. We demonstrate that TRPV6D541A/D541A mice exhibit impaired transcellular Ca2+ absorption. Duodenal TRPV5 expression was increased in TRPV6D541A/D541A mice, albeit insufficient to correct for the diminished Ca2+ absorption. Under normal conditions, when passive Ca2+ transport is predominant, no differences between wild-type and TRPV6D541A/D541A mice were observed. Our results demonstrate a specific role for TRPV6 in transepithelial Ca2+ absorption

CNNM2 Mutations Cause Impaired Brain Development and Seizures in Patients with

Intellectual disability and seizures are frequently associated with hypomagnesemia and have an important genetic component. However, to find the genetic origin of intellectual disability and seizures often remains challenging because of considerable genetic heterogeneity and clinical variability. In this study, we have identified new mutations in CNNM2 in five families suffering from mental retardation, seizures, and hypomagnesemia. For the first time, a recessive mode of inheritance of CNNM2 mutations was observed. Importantly, patients with recessive CNNM2 mutations suffer from brain malformations and severe intellectual disability. Additionally, three patients with moderate mental disability were shown to carry de novo heterozygous missense mutations in the CNNM2 gene. To elucidate the physiological role of CNNM2 and explain the pathomechanisms of disease, we studied CNNM2 function combining in vitro activity assays and the zebrafish knockdown model system. Using stable Mg2+ isotopes, we demonstrated that CNNM2 increases cellular Mg2+ uptake in HEK293 cells and that this process occurs through regulation of the Mg2+-permeable cation channel TRPM7. In contrast, cells expressing mutated CNNM2 proteins did not show increased Mg2+ uptake. Knockdown of cnnm2 isoforms in zebrafish resulted in disturbed brain development including neurodevelopmental impairments such as increased embryonic spontaneous contractions and weak touch-evoked escape behaviour, and reduced body Mg content, indicative of impaired renal Mg2+ absorption. These phenotypes were rescued by injection of mammalian wild-type Cnnm2 cRNA, whereas mammalian mutant Cnnm2 cRNA did not improve the zebrafish knockdown phenotypes. We therefore concluded that CNNM2 is fundamental for brain development, neurological functioning and Mg2+ homeostasis. By establishing the loss-of-function zebrafish model for CNNM2 genetic disease, we provide a unique system for testing therapeutic drugs targeting CNNM2 and for monitoring their effects on the brain and kidney phenotype. Author Summary Mental retardation affects 1-3% of the population and has a strong genetic etiology. Consequently, early identification of the genetic causes of mental retardation is of significant importance in the diagnosis of the disease, as predictor of the progress of the disease and for the determination of treatment. In this study, we identify mutations in the gene encoding for cyclin M2 (CNNM2) to be causative for mental retardation and seizures in patients with hypomagnesemia. Particularly, in patients with a recessive mode of inheritance, the intellectual disability caused by dysfunctional CNNM2 is dramatically severe and is accompanied by severely limited motor skills and brain malformations suggestive of impaired early brain development. Although hypomagnesemia has been associated to several neurological diseases, Mg2+ status is not regularly assessed in patients with seizures and mental disability. Our findings establish CNNM2 as an important protein for renal magnesium handling, brain development and neurological functioning, thus explaining the physiology of human disease caused by (dysfunctional) mutations in CNNM2. CNNM2 mutations should be taken into account in patients with seizures and mental disability, specifically in combination with hypomagnesemia

Cellular Akt and ERK signaling is unaffected by FL3.

<p>HEK293 cells were incubated with FL2 (50 nM), FL3 (50 nM), PMA (100 nM), insulin (10 nM) or 17βE (50 nM) for 15 minutes. Protein lysates were immediately obtained and immunoblots were performed to detect pERK1/2 and pAkt. PMA and insulin served as positive controls for ERK and Akt phosphorylation, respectively.</p

The presence of the intrinsic alpha-kinase domain of the channel but not its activity is required for flavagline-mediated stimulation of TRPM6.

<p><b>a.</b> The average time-course of current development of the kinase-inactive channels (TRPM6^K1804R) with (n = 7, full symbols) or without (n = 9, empty symbols) FL23 (50 nM) pre-incubation is shown for current values measured at +80 mV. <b>b.</b> The average time-course of current development of TRPM6^L1749X (Δkinase) with (n = 8, full symbols) or without (n = 9, empty symbols) FL23 (50 nM) pre-incubation is shown for current values measured at +80 mV. <b>c.</b> Pre-incubation of cells with FL23 (50 nM) stimulated wild type (n≥22), K1804R (n≥9), but not Δkinase (n≥8, p>0.05) channel activity. Right panel shows current values normalized to each control condition. Stars indicate statistically significant difference (P<0.05) between vehicle- (white bar) and compound-treated cells (black bar).</p

Analogs of FL23 show distinct effects on TRPM6 currents.

<p><b>a.</b> Typical current-voltage curves obtained 200 s after break-in are shown for vehicle and FL23 (50 nM) pre-incubated cells. <b>b.</b> The average time-course of TRPM6 current development with (n = 8) or without (n = 11) FL23 (50 nM) is shown for current values measured at +80 mV. <b>c.</b> The average time-course of TRPM6 current development with FL2 (50 nM, n = 12), vehicle (n = 10) or FL23 (50 nM, n = 10) pre-treatment is shown for current values measured at +80 mV. <b>d.</b> FL2 incubation did not significantly stimulate TRPM6 activity (n≥10). Stars indicate statistically significant difference (P<0.05) between vehicle and compound-treated cells.</p

Proposed model of flavaglines action.

<p>Flavaglines stimulate TRPM6 activity by acting on downstream effector(s) of the insulin receptor. PHB2 and CDK5, proteins which are known to regulate TRPM6 are localized in lipid rafts.</p

Flavaglines act upon a common pathway with insulin receptor signaling.

<p><b>a-d.</b> The average time-course of current development of cells pre-incubated with (full symbols) or without (empty symbols) FL23 (50 nM) for: (<b>a</b>) TRPM6^V1393I (n≥8), (<b>b</b>) TRPM6^K1584E (n≥7), (<b>c</b>) wild type TRPM6 together with Rac1^T17N (n≥6) and (<b>d</b>) wild type TRPM6 together with Rac1^G12V (n≥11). <b>e.</b> FL23 pre-incubation failed to alter currents in cells expressing TRPM6^V1393I (n = 11), TRPM6^K1584E (n≥8) and cells co-expressing wild type TRPM6 together with Rac1^T17N (n = 8) and TRPM6 together with Rac1^G12V (n≥14). Right panel shows current values normalized to each control condition. Stars indicate statistically significant difference (P<0.05) between vehicle- (white bar) and compound-treated cells (black bar).</p