Protective effects of Gαi3 deficiency in a murine heart-failure model of β1-adrenoceptor overexpression

We have shown that in murine cardiomyopathy caused by overexpression of the β1-adrenoceptor, Gαi2-deficiency is detrimental. Given the growing evidence for isoform-specific Gαi-functions, we now examined the consequences of Gαi3 deficiency in the same heart-failure model. Mice overexpressing cardiac β1-adrenoceptors with (β1-tg) or without Gαi3-expression (β1-tg/Gαi3-/-) were compared to C57BL/6 wildtypes and global Gαi3-knockouts (Gαi3-/-). The life span of β1-tg mice was significantly shortened but improved when Gαi3 was lacking (95% CI: 592-655 vs. 644-747 days). At 300 days of age, left-ventricular function and survival rate were similar in all groups. At 550 days of age, β1-tg but not β1-tg/Gαi3-/- mice displayed impaired ejection fraction (35 ± 18% vs. 52 ± 16%) compared to wildtype (59 ± 4%) and Gαi3-/- mice (60 ± 5%). Diastolic dysfunction of β1-tg mice was prevented by Gαi3 deficiency, too. The increase of ANP mRNA levels and ventricular fibrosis observed in β1-tg hearts was significantly attenuated in β1-tg/Gαi3-/- mice. Transcript levels of phospholamban, ryanodine receptor 2, and cardiac troponin I were similar in all groups. However, Western blots and phospho-proteomic analyses showed that in β1-tg, but not β1-tg/Gαi3-/- ventricles, phospholamban protein was reduced while its phosphorylation increased. Here, we show that in mice overexpressing the cardiac β1-adrenoceptor, Gαi3 deficiency slows or even prevents cardiomyopathy and increases shortened life span. Previously, we found Gαi2 deficiency to aggravate cardiac dysfunction and mortality in the same heart-failure model. Our findings indicate isoform-specific interventions into Gi-dependent signaling to be promising cardio-protective strategies.

Implementing nutritional medicine into medical curricula: A student-initiated course improves knowledge and attitudes

BACKGROUND & AIMS

Although the risks and opportunities of nutrition in health trajectories are well known, it is rarely addressed in doctors' daily routine. This is partly related to physicians' lack of confidence in their ability to provide nutritional counselling, possibly due to insufficient training in medical school. Our study aimed at assessing the status quo of nutrition in the German medical curricula and the impact of a recently implemented, student-initiated online teaching initiative on perceived competence, knowledge and attitudes.

METHODS

"Eat This!" was the first Germany-wide initiative for online nutritional medicine (NM) education, consisting of 11 digital lectures on nutrition basics, nutrition medicine and public health nutrition. The contact time with NM during studies as well as the effects on students' attitudes towards NM, their self-perceived competence in NM and their nutrition knowledge were assessed from October 2020 to February 2021 in a cross-sectional as well as a prospective study using online questionnaires.

RESULTS

Over 1500 medical students from 42 German faculties participated in the lecture series and the online survey. One hundred and twenty-two students formed a control group. Although considering the topic relevant, students rated their training in NM as insufficient, in terms of both quality and quantity. Initially, they did not feel able to counsel patients and rated their knowledge as low. However, self-ratings and the score in a 33-item multiple-choice test knowledge improved by participating in Eat This! as did their attitude towards nutrition and planetary health. No such changes were observed in the control group of 122 students not attending the course.

CONCLUSION

Our results show that education in NM at German medical schools is perceived insufficient despite high student interest. But even low-threshold educational options like "Eat This!" can improve students' perceived competence, knowledge, and attitudes, and thus be an efficient and cost-effective way to address related deficits.

A comparison of urinary bladder weight in male and female mice across five models of diabetes and obesity

Introduction: Diabetes often leads to lower urinary tract dysfunction. The most frequently assessed parameter of urinary bladder dysfunction in animal models of diabetes is an enlargement of the bladder, which is consistently observed in type 1 and less consistently in type 2 diabetes. The vast majority of studies on bladder weight in animal models of diabetes and obesity has been performed in males, and no studies have directly compared this outcome parameter between sexes. Methods: Therefore, we have compared bladder weight and bladder/body weight ratio in five mouse models of obesity and diabetes (RIP-LCMV, db/db, ob/ob (two studies), insulin receptor substrate 2 (IRS2) knock-out mice and mice on a high-fat diet; pre-specified secondary analysis of a previously reported study). Results: In a pooled analysis of the control groups of all studies, females exhibited slightly lower glucose levels, lower body weight, and lower bladder weight, but bladder/body weight ratio was similar in both sexes (0.957 vs. 0.986 mg/g, mean difference 0.029 [-0.06; 0.118]). Among the six diabetic/obese groups, bladder/body weight ratio was similar in both sexes in three but smaller in female mice in three other groups. The mRNA expression of a panel of genes implied in the pathophysiology of bladder enlargement and/or fibrosis and inflammation did not differ systematically between sexes. Conclusions: We conclude that sex differences in diabetes/obesity-associated bladder enlargement may be model dependent.

Improvement of Dietary Habits among German Medical Students by Attending a Nationwide Online Lecture Series on Nutrition and Planetary Health ("Eat This!")

Nutrition is a major influential factor in optimizing human health and environmental sustainability. Medical students often do not follow national dietary guideline recommendations. Raising awareness of a healthy lifestyle is important as physicians with healthy lifestyle behaviors are more likely to counsel on nutrition. Our study aims to evaluate a Germany-wide online lecture series on nutritional medicine, "Eat This!". Before and after the course, 520 medical students who participated and 64 who did not participate in the course (comparison group) filled out an online survey. To assess the students' dietary habits, a validated FFQ was used. According to this questionnaire, only 31% of the lecture participants consumed enough fruits and 24% consumed enough vegetables, while almost half of the students exceeded the recommended maximum amount of crisps and sweets. After attending the lecture series, guideline adherence with respect to fruits and vegetables showed a significant increase, as did awareness of healthy nutrition and percentage of students with low-risk lifestyle habits. Our results show that low-threshold approaches, such as "Eat This!", can positively influence the dietary behaviors and lifestyle habits of medical students. This can help future doctors fulfill their role in the fight against the global burden of non-communicable diseases.

Analysis of 16 studies in nine rodent models does not support the hypothesis that diabetic polyuria is a main reason of urinary bladder enlargement

The urinary bladder is markedly enlarged in the type 1 diabetes mellitus model of streptozotocin-injected rats, which may contribute to the frequent diabetic uropathy. Much less data exists for models of type 2 diabetes. Diabetic polyuria has been proposed as the pathophysiological mechanism behind bladder enlargement. Therefore, we explored such a relationship across nine distinct rodent models of diabetes including seven models of type 2 diabetes/obesity by collecting data on bladder weight and blood glucose from 16 studies with 2–8 arms each; some studies included arms with various diets and/or pharmacological treatments. Data were analysed for bladder enlargement and for correlations between bladder weight on the one and glucose levels on the other hand. Our data confirm major bladder enlargement in streptozotocin rats and minor if any enlargement in fructose-fed rats, db/db mice and mice on a high-fat diet; enlargement was present in some of five not reported previously models. Bladder weight was correlated with blood glucose as a proxy for diabetic polyuria within some but not other models, but correlations were moderate to weak except for RIP-LCMV mice (r² of pooled data from all studies 0.0621). Insulin levels also failed to correlate to a meaningful extent. Various diets and medications (elafibranor, empagliflozin, linagliptin, semaglutide) had heterogeneous effects on bladder weight that often did not match their effects on glucose levels. We conclude that the presence and extent of bladder enlargement vary markedly across diabetes models, particularly type 2 diabetes models; our data do not support the idea that bladder enlargement is primarily driven by glucose levels/glucosuria.

Inhibitory effects on L- and N-type calcium channels by a novel CaVβ1 variant identified in a patient with autism spectrum disorder

Voltage-gated calcium channel (VGCC) subunits have been genetically associated with autism spectrum disorders (ASD). The properties of the pore-forming VGCC subunit are modulated by auxiliary β-subunits, which exist in four isoforms (Ca_Vβ_1-4). Our previous findings suggested that activation of L-type VGCCs is a common feature of Ca_Vβ₂ subunit mutations found in ASD patients. In the current study, we functionally characterized a novel Ca_Vβ_1b variant (p.R296C) identified in an ASD patient. We used whole-cell and single-channel patch clamp to study the effect of Ca_Vβ_{1b_R296C} on the function of L- and N-type VGCCs. Furthermore, we used co-immunoprecipitation followed by Western blot to evaluate the interaction of the Ca_Vβ_1b-subunits with the RGK-protein Gem. Our data obtained at both, whole-cell and single-channel levels, show that compared to a wild-type Ca_Vβ_1b, the Ca_Vβ_{1b_R296C} variant inhibits L- and N-type VGCCs. Interaction with and modulation by the RGK-protein Gem seems to be intact. Our findings indicate functional effects of the Ca_Vβ_{1b_R296C} variant differing from that attributed to Ca_Vβ₂ variants found in ASD patients. Further studies have to detail the effects on different VGCC subtypes and on VGCC expression.

Depolarization induces nociceptor sensitization by CaV1.2-mediated PKA-II activation

Depolarization drives neuronal plasticity. However, whether depolarization drives sensitization of peripheral nociceptive neurons remains elusive. By high-content screening (HCS) microscopy, we revealed that depolarization of cultured sensory neurons rapidly activates protein kinase A type II (PKA-II) in nociceptors by calcium influx through Ca_V1.2 channels. This effect was modulated by calpains but insensitive to inhibitors of cAMP formation, including opioids. In turn, PKA-II phosphorylated Ser1928 in the distal C terminus of Ca_V1.2, thereby increasing channel gating, whereas dephosphorylation of Ser1928 involved the phosphatase calcineurin. Patch-clamp and behavioral experiments confirmed that depolarization leads to calcium- and PKA-dependent sensitization of calcium currents ex vivo and local peripheral hyperalgesia in the skin in vivo. Our data suggest a local activity-driven feed-forward mechanism that selectively translates strong depolarization into further activity and thereby facilitates hypersensitivity of nociceptor terminals by a mechanism inaccessible to opioids.

A simulation-based module in pharmacology education reveals and addresses medical students' deficits in leading prescription talks

Although doctor-patient communication is essential for drug prescription, the literature reveals deficits in this area. An educational approach at the Cologne medical faculty aims at identifying and addressing those deficits in medical students.Fifth-year medical students first conducted a simulated prescription talk spontaneously. Subsequently, the conversation was discussed with peer students. A pharmacist moderated the discussion based upon a previously developed conversation guide. Afterwards, the same student had the conversation again, but as if for the first time. Conversations were video-recorded, transcribed and subjected to quantitative content analysis. Four days after the simulation, the students who conducted the talk, those who observed and discussed it, and students who did neither, completed a written test that focused on the content of an effective prescription talk.Content analysis revealed clear deficits in spontaneously led prescription talks. Even essential information as on adverse drug reactions were often lacking. Prescription talks became clearly more informative and comprehensive after the short, guided peer discussion. With regard to a comprehensive, informative prescription talk, the written test showed that both the students who conducted the talk and those who only observed it performed clearly better than the students who did not participate in the educational approach.Deficits regarding prescription talks are present in 5^th year medical students. We provide an approach to both identify and address these deficits. It thus may be an example for training medical students in simulated and clinical environments like the EACPT recommended to improve pharmacology education.

Inhibition of EIF-5A prevents apoptosis in human cardiomyocytes after malaria infection

In this study, a determination of Troponin I and creatine kinase activity in whole-blood samples in a cohort of 100 small infants in the age of 2-5 years from Uganda with complicated Plasmodium falciparum malaria suggests the prevalence of cardiac symptoms in comparison to non-infected, healthy patients. Troponin I and creatine kinase activity increased during infection. Different reports showed that complicated malaria coincides with hypoxia in children. The obtained clinical data prompted us to further elucidate the underlying regulatory mechanisms of cardiac involvement in human cardiac ventricular myocytes. Complicated malaria is the most common clinical presentation and might induce cardiac impairment by hypoxia. Eukaryotic initiation factor 5A (eIF-5A) is involved in hypoxia induced factor (HIF-1α) expression. EIF-5A is a protein posttranslationally modified by hypusination involving catalysis of the two enzymes deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase. Treatment of human cardiomyocytes with GC7, an inhibitor of DHS, catalyzing the first step in hypusine biosynthesis led to a decrease in proinflammatory and proapoptotic myocardial caspase-1 activity in comparison to untreated cardiomyocytes. This effect was even more pronounced after co-administration of GC7 and GPI from P. falciparum simulating the pathology of severe malaria. Moreover, in comparison to untreated and GC7-treated cardiomyocytes, co-administration of GC7 and GPI significantly decreased the release of cytochrome C and lactate from damaged mitochondria. In sum, coadministration of GC7 prevented cardiac damage driven by hypoxia in vitro. Our approach demonstrates the potential of the pharmacological inhibitor GC7 to ameliorate apoptosis in cardiomyocytes in an in vitro model simulating severe malaria. This regulatory mechanism is based on blocking EIF-5A hypusination.

Direct, gabapentin-insensitive interaction of a soluble form of the calcium channel subunit α2δ-1 with thrombospondin-4

The α₂δ‐1 subunit of voltage-gated calcium channels binds to gabapentin and pregabalin, mediating the analgesic action of these drugs against neuropathic pain. Extracellular matrix proteins from the thrombospondin (TSP) family have been identified as ligands of α₂δ‐1 in the CNS. This interaction was found to be crucial for excitatory synaptogenesis and neuronal sensitisation which in turn can be inhibited by gabapentin, suggesting a potential role in the pathogenesis of neuropathic pain. Here, we provide information on the biochemical properties of the direct TSP/α₂δ-1 interaction using an ELISA-style ligand binding assay. Our data reveal that full-length pentameric TSP-4, but neither TSP-5/COMP of the pentamer-forming subgroup B nor TSP-2 of the trimer-forming subgroup A directly interact with a soluble variant of α₂δ-1 (α₂δ-1_S). Interestingly, this interaction is not inhibited by gabapentin on a molecular level and is not detectable on the surface of HEK293-EBNA cells over-expressing α₂δ‐1 protein. These results provide biochemical evidence that supports a specific role of TSP-4 among the TSPs in mediating the binding to neuronal α₂δ‐1 and suggest that gabapentin does not directly target TSP/α₂δ-1 interaction to alleviate neuropathic pain.

"Hopefully, I will never forget that again" - sensitizing medical students for drug safety by working on cases and simulating doctor-patient communication

Objective: This project is part of the "PJ-STArT-Block", a one-week course preparing 10^th semester medical students for their final practical year. The focus is on sensitizing students to aspects of medication safety by becoming aware of their skills and their deficits in terms of application and communication of pharmacological knowledge. The modules were evaluated regarding feasibility, acceptance and possible effects. Furthermore, the areas in which students see their pharmacological deficits or learning successes were gathered. Methods: In simulated physician-patient conversations, the students are to identify drug-related problems such as medication errors, adverse drug events or interactions. Together with their fellow students and under medical or pharmaceutical moderation, they then have to find solutions for the identified problems and communicate these solutions to the patients. Based on paper cases, students practice, reflect, and discuss the research of reliable information about drugs and medication therapy. The written evaluation included the evaluation by school grades and the possibility of comments in free text. A content analysis of interviews with students at the beginning of the project aimed to identify areas of pharmacology in which they see their own deficits. Results: Evaluation results including the free text comments indicate students' acceptance of our pharmacology modules. According to this, the students realize the importance of aspects relevant for medication safety. The areas mentioned in 35 interviews in which students localize deficits, correspond to the topics that were intended when conceiving the modules and which are important for medication safety (e.g. interactions, adverse drug effects, dosages). Conclusion: Implementation of context-based, application-oriented teaching formats as recently claimed for pharmacological education to improve the quality of prescriptions, is possible, as the Cologne example shows. The student evaluation turns out positively and indicates a critical self-reflection. The students identified various pharmacological deficits in themselves, which have since been confirmed and quantified in another study.

Does teaching social and communicative competences influence dental students' attitudes towards learning communication skills? A comparison between two dental schools in Germany

Introduction: Teaching social and communicative competences has become an important part of undergraduate dental education. The aim of this study was to explore the influence of a longitudinal curriculum, addressing social and communication skills, on dental students' attitudes towards learning these skills. Material and methods: Data on the attitudes towards learning communication skills were collected at two German universities and compared in a cross-sectional survey. 397 dental students were included, 175 students attended a longitudinal curriculum addressing social and communicative competences while 222 students did not. The dental students' attitude towards learning communication skills was measured by a German version of the Communication Skills Attitude Scale (CSAS-D). Results: Dental students who participated in a longitudinal communication curriculum had significantly lower negative attitudes towards learning communication skills than students who did not attend such courses. Differences in positive attitudes could not be found. Significant interaction effects were found for the factors gender and section of study: female students in the clinical section of their study who participated in the longitudinal curriculum reported higher positive attitudes and lower negative attitudes compared to female students in the preclinical section of study. Conclusion: The results of this study indicate that a longitudinal curriculum addressing communication skills can enhance positive and reduce negative attitudes towards learning communication skills. More longitudinal data is needed to explore to what extent gender affects development of communication skills and how students' attitudes towards learning communication change in the long run.

Renal Metabolic Programming Is Linked to the Dynamic Regulation of a Leptin-Klf15 Axis and Akt/AMPKα Signaling in Male Offspring of Obese Dams

Childhood obesity is associated with renal diseases. Maternal obesity is a risk factor linked to increased adipocytokines and metabolic disorders in the offspring. Therefore, we studied the impact of maternal obesity on renal-intrinsic insulin and adipocytokine signaling and on renal function and structure. To induce maternal obesity, female mice were fed a high-fat diet (HFD) or a standard diet (SD; control group) prior to mating, during gestation, and throughout lactation. A third group of dams was fed HFD only during lactation (HFD-Lac). After weaning at postnatal day (P)21, offspring of all groups received SD. Clinically, HFD offspring were overweight and insulin resistant at P21. Although no metabolic changes were detected at P70, renal sodium excretion was reduced by 40%, and renal matrix deposition increased in the HFD group. Mechanistically, two stages were differentiated. In the early stage (P21), compared with the control group, HFD showed threefold increased white adipose tissue, impaired glucose tolerance, hyperleptinemia, and hyperinsulinemia. Renal leptin/Stat3-signaling was activated. In contrast, the Akt/ AMPKα cascade and Krüppel-like factor 15 expression were decreased. In the late stage (P70), although no metabolic differences were detected in HFD when compared with the control group, leptin/Stat3-signaling was reduced, and Akt/AMPKα was activated in the kidneys. This effect was linked to an increase of proliferative (cyclinD1/D2) and profibrotic (ctgf/collagen IIIα1) markers, similar to leptin-deficient mice. HFD-Lac mice exhibited metabolic changes at P21 similar to HFD, but no other persistent changes. This study shows a link between maternal obesity and metabolic programming of renal structure and function and intrinsic-renal Stat3/Akt/AMPKα signaling in the offspring.

Publication activity in medical education research: A descriptive analysis of submissions to the GMS Zeitschrift für Medizinische Ausbildung in 2007-2015

Objectives: The significance of medical education research has increased internationally. In this context we investigated whether, and if so, how the quantity and quality of scientific papers reviewed and/or published by the GMS Zeitschrift für Medizinische Ausbildung (GMS Z Med Ausbild) changed. Methods: The quantity and ratio of original papers, project reports and reviews submitted to or published in the GMS Z Med Ausbild were analysed. Published scientific articles were investigated in regard to the quality features "study type" and "mode of data collection" as well as the background (university affiliation) of the last authors. The citation frequency within the first five years after PubMed listing was compared to the one of BMC Medical Education in the corresponding period. Results: The number of submitted scientific manuscripts increased steadily. Most of the submissions and publications are original papers. For publications explorative studies and prospective data collection are most common. A shift over time is not observed. 16% of the published works come from one and 36% from four of the in total 39 universities represented by the last authors. The development of the citation frequency of articles published in GMS Z Med Ausbild is similar to that of BMC Medical Education. Conclusion: The rising number of submissions indicates an increasing significance of medical education research in German-speaking countries. The development of the number of citations reflects the growing appreciation of GMS Z Med Ausbild also indicated by the increasing number of online accesses. Our findings that study type and mode of data collection did not change has to be interpreted with caution since among other things choice and correct application of adequate methods are crucial regarding a scientific work's quality, too. These aspects, however, were not investigated in this paper.

Beta-adrenergic regulation of the heart expressing the Ser1700A/Thr1704A mutated Cav1.2 channel

Beta-adrenergic stimulation of the heart increases I_Ca. PKA dependent phosphorylation of several amino acids (among them Ser 1700 and Thr 1704 in the carboxy-terminus of the Cav1.2 α₁c subunit) has been implicated as decisive for the β-adrenergic up-regulation of cardiac I_Ca. Mutation of Ser 1700 and Thr 1704 to alanine results in the Cav1.2PKA_P2^-/- mice. Cav1.2PKA_P2^-/- mice display reduced cardiac L-type current. Fractional shortening and ejection fraction in the intact animal and I_Ca in isolated cardiomyocytes (CM) are stimulated by isoproterenol. Cardiac specific expression of the mutated Cav1.2PKA_P2^-/- gene reduces Cav1.2 α₁c protein concentration, I_Ca, and the β-adrenergic stimulation of L-type I_Ca in CMs. Single channels were not detected on the CM surface of the cCav1.2PKA_P2^-/- hearts. This outcome supports the notion that S1700/1704 is essential for expression of the Cav1.2 channel and that isoproterenol stimulates I_Ca in Cav1.2PKA_P2^-/- CMs.

A multi-centre student survey on weighing disciplines in medical curricula - a pilot study

Aim: Initiated by students, this pilot study examines how obtaining medical students' perspectives via a structured online survey may prove useful for curriculum deliberation. Methods: In 2012, 747 students of 32 medical faculties in Germany assessed disciplines specified in the Medical Licensure Act (AÄpprO) thereby concerning the allocation of teaching time, perceived usefulness regarding preparation for state examination and medical practice, their interest and motivation for studying as well as consideration for future work. Results: Internal medicine, surgery, paediatrics, gynaecology/obstetrics and general medicine rank amongst the upper third regarding allocation of teaching time and perceived usefulness for future medical practice. Concerning both preparation for state examination and medical practice internal medicine ranks second, while surgery only 22^nd and 28^th of 32, respectively. Some clinical-theoretical disciplines (e.g. pharmacology) are in the top ten regarding perceived preparation for state examination, too. Students who consider choosing internal medicine for future work rate associated disciplines significantly higher regarding usefulness for clinical practice (e.g. pharmacology) or motivation for studying (e.g. microbiology) than other students do. Conclusion: A simple survey reveals interesting data on students' perceptions and ideas of medical studies. Though the data are plausible, interpretations should be done with caution. Nonetheless, data like these should give rise to further questions and discussions, e.g. as part of curriculum deliberation.

The prescription talk - an approach to teach patient-physician conversation about drug prescription to medical students

Background: Medication communication from physicians to patients often is poor, by this among others enhancing the risk of non-adherence. In this context, a neglect regarding the prescription talk has been complained. Aim of the project: In a newly developed elective medical students work on physician-patient conversations dealing with drug prescription. Essential aspects related to an effective and safe drug treatment are combined with steps of shared decision-making. Together with a tutor, students develop a (model) conversation guide that might be tailored according to individual needs and views. Description/Methods: In a one-week course 3rd-5th year medical students treat a paper case according to problem-based learning. This is accompanied by a one-hour lecture and literature provided on an online learning platform (ILIAS). During a workshop, aspects of drug treatment and patient participation are integrated into a guide for a prescription talk. At the end of the week the students are invited to apply the (if need be individualized) guide in a simulated physician-patient communication with an actor. The conversation is evaluated using a checklist based upon the (model) conversation guide. Results: Informal and formalized feedback indicate high acceptance and satisfaction of participants with this elective. The checklist turned out to be of acceptable to good reliability with mostly selective items. Portfolio entries and written evaluation suggest that participants' positions and attitudes are influenced.

Medical students' medication communication skills regarding drug prescription-a qualitative analysis of simulated physician-patient consultations

PURPOSE

Poor medication communication of physicians to patients is detrimental, e.g. for medication adherence. Reasons for physicians' deficits in medication communication may be unfavourable conditions in daily practice or already insufficient training during their (undergraduate) medical studies. We explored medical students' communication on new medications in simulated physician-patient conversations to identify actual deficits indicating apparent educational needs.

METHODS

Fifth year medical students attending a mandatory course at the University of Cologne had simulated physician-patient consultations aiming at drug prescription. In 2015, 21 consultations were recorded, transcribed and subjected to qualitative content analysis based on the method of inductive coding.

RESULTS

Even essential information on drug therapy was often lacking (e.g. adverse effects, drug administration). Some aspects were addressed more frequently than others. This seemed to differ depending on the diagnosis underlying the particular treatment (acute event vs. chronic disease). The extent of information on drug treatments given in simulated physician-patient consultations varied significantly between students.

CONCLUSIONS

Fifth year medical students showed appreciable deficits in communicating drug prescriptions to patients though there were remarkable inter-individual differences. Our findings suggest that communication on drug therapy to patients is no self-evolving skill. Thus, there is obviously a need for emphasizing medication communication in the training of medical students. Communication aids specifically aiming at medication communication might facilitate learning of adequate medication communication skills.

Outcome-Relevant Effects of Shared Decision Making

BACKGROUND

Shared decision making (SDM) is considered a gold standard for the cooperation of doctor and patient. SDM improves patients' overall satisfaction and their confidence in decisions that have been taken. The extent to which it might also positively affect patient-relevant, disease-related endpoints is a matter of debate.

METHODS

We systematically searched the PubMed database and the Cochrane Library for publications on controlled intervention studies of SDM. The quality of the intervention and the risk of bias in each publication were assessed on the basis of pre-defined inclusion and exclusion criteria. The effects of SDM on patient-relevant, disease-related endpoints were compared, and effect sizes were calculated.

RESULTS

We identified 22 trials that differed widely regarding the patient populations studied, the types of intervention performed, and the mode of implementation of SDM. In ten articles, 57% of the endpoints that were considered relevant were significantly improved by the SDM intervention compared to the control group. The median effect size (Cohen's d) was 0.53 (0.14-1.49). In 12 trials, outcomes did not differ between the two groups. In all 22 studies identified, 39% of the relevant outcomes were significantly improved compared with the control groups.

CONCLUSION

The trials performed to date to addressing the effect of SDM on patient-relevant, disease-related endpoints are insufficient in both quantity and quality. Although just under half of the trials reviewed here indicated a positive effect, no final conclusion can be drawn. A consensus-based standardization of both SDM-promoting measures and appropriate clinical studies are needed.

An expert protocol for immunofluorescent detection of calcium channels in tsA-201 cells

INTRODUCTION

Pore-forming subunits of voltage gated calcium channels (VGCC) are large membrane proteins (260kDa) containing 24 transmembrane domains. Despite transfection with viral promoter driven vectors, biochemical analysis of VGCC is often hampered by rather low expression levels in heterologous systems rendering VGCC challenging targets. Especially in immunofluorescent detection, calcium channels are demanding proteins.

METHODS

We provide an expert step-by-step protocol with adapted conditions for handling procedures (tsA-201 cell culture, transient transfection, incubation time and temperature at 28°C or 37°C and immunostaining) to address the L-type calcium-channel pore Ca_v1.2 in an immunofluorescent approach.

RESULTS

We performed immunocytochemical analysis of Ca_v1.2 expression at single-cell level in combination with detection of different markers for cellular organelles. We show confluency levels and shapes of tsA-201 cells at different time points during an experiment. Our experiments reveal sufficient levels of Ca_v1.2 protein and a correct Ca_v1.2 expression pattern in polygonal shaped cells already 12h after transfection.

DISCUSSION

A sequence of elaborated protocol modifications allows subcellular localization analysis of Ca_v1.2 in an immunocytochemical approach. We provide a protocol that may be used to achieve insights into physiological and pathophysiological processes involving voltage gated calcium channels. Our protocol may be used for expression analysis of other challenging proteins and efficient overexpression may be exploited in related biochemical techniques requiring immunolabels.

Peyton's 4-Steps-Approach in comparison: Medium-term effects on learning external chest compression - a pilot study

INTRODUCTION

The external chest compression is a very important skill required to maintain a minimum of circulation during cardiac arrest until further medical procedures can be taken. Peyton's 4-Steps-Approach is one method of skill training, the four steps being: Demonstration, Deconstruction, Comprehension and Execution. Based on CPR skill training, this method is widely, allegedly predominantly used, although there are insufficient studies on Peyton's 4-Steps-Approach for skill training in CPR in comparison with other methods of skill training. In our study, we compared the medium- term effects on learning external chest compression with a CPR training device in three different groups: PEY (Peyton's 4-Steps-Approach), PMOD (Peyton's 4-Steps-Approach without Step 3) and STDM, the standard model, according to the widely spread method "see one, do one" (this is equal to Peyton's step 1 and 3).

MATERIAL AND METHODS

This prospective and randomised pilot study took place during the summer semester of 2009 at the SkillsLab and Simulation Centre of the University of Cologne (Kölner interprofessionelles Skills Lab und Simulationszentrum - KISS). The subjects were medical students (2(nd) and 3(rd) semester). They volunteered for the study and were randomised in three parallel groups, each receiving one of the teaching methods mentioned above. One week and 5/6 months after the intervention, an objective, structured single assessment was taken. Compression rate, compression depth, correct compressions, and the sum of correct checklist items were recorded. Additionally, we compared cumulative percentages between the groups based on the correct implementation of the resuscitation guidelines during that time.

RESULTS

The examined sample consisted of 134 subjects (68% female; age 22±4; PEY: n=62; PMOD: n=31; STDM: n=41). There was no difference between the groups concerning age, gender, pre-existing experience in CPR or time of last CPR course. The only significant difference between the groups was the mean compression rate (bpm): Group 1 (PEY) with 99±17 bpm, Group 2 (PMOD) with 101±16 bpm and Group 3 (STDM) with 90±16 bpm (p=0,007 for Group 3 vs. Group 1 and Group 3 vs. Group 2, Mann-Whitney- U-Test). We observed no significant differences between the groups after the second assessment.

CONCLUSION

Our study showed that there are no essential differences in external chest compression during CPR performed by medical students dependent on the teaching method (Peyton vs. "Non-Peyton") implemented with regard to the medium-term effects. The absence of benefits could possibly be due to the simplicity of external chest compression.

Voltage-gated Calcium Channels and Autism Spectrum Disorders

Autism spectrum disorder is a complex-genetic disease and its etiology is unknown for the majority of cases. So far, more than one hundred different susceptibility genes were detected. Voltage-gated calcium channels are among the candidates linked to autism spectrum disorder by results of genetic studies. Mutations of nearly all pore-forming and some auxiliary subunits of voltage gated calcium channels have been revealed from investigations of autism spectrum disorder patients and populations. Though there are only few electrophysiological characterizations of voltage-gated calcium channel mutations found in autistic patients these studies suggest their functional relevance. In summary, both genetic and functional data suggest a potential role of voltage-gated calcium channels in autism spectrum disorder. Future studies require refinement of the clinical and systems biological concepts of autism spectrum disorder and an appropriate holistic approach at the molecular level, e.g. regarding all facets of calcium channel functions.

Robust Generation of Cardiomyocytes from Human iPS Cells Requires Precise Modulation of BMP and WNT Signaling

Various strategies have been published enabling cardiomyocyte differentiation of human induced pluripotent stem (iPS) cells. However the complex nature of signaling pathways involved as well as line-to-line variability compromises the application of a particular protocol to robustly obtain cardiomyocytes from multiple iPS lines. Hence it is necessary to identify optimized protocols with alternative combinations of specific growth factors and small molecules to enhance the robustness of cardiac differentiation. Here we focus on systematic modulation of BMP and WNT signaling to enhance cardiac differentiation. Moreover, we improve the efficacy of cardiac differentiation by enrichment via lactate. Using our protocol we show efficient derivation of cardiomyocytes from multiple human iPS lines. In particular we demonstrate cardiomyocyte differentiation within 15 days with an efficiency of up to 95 % as judged by flow cytometry staining against cardiac troponin T. Cardiomyocytes derived were functionally validated by alpha-actinin staining, transmission electron microscopy as well as electrophysiological analysis. We expect our protocol to provide a robust basis for scale-up production of functional iPS cell-derived cardiomyocytes that can be used for cell replacement therapy and disease modeling.

A study on effects of and stance over tuition fees

AIM

Regarding tuition fees (that in Germany already have been abrogated) putative drawbacks like prolonged study duration have been suspected while benefits are not clearly proven. We investigated whether tuition fees (500 Euro per semester) affected the course of studies of Cologne medical students and asked for students' stance over tuition fees.

METHODS

Of 1,324 students we analyzed the rate of those passing their first medical exam ("Physikum") within minimum time and students' discontinuation rate, respectively. Regression analysis tested for putative influences of tuition fees and demographic factors. In an additional online survey 400 students answered questions regarding the load by and their stance over tuition fees.

RESULTS

We find that fees did not affect rate of Cologne students passing their first medical exam within minimum time or students' discontinuation rate. According to the online survey, at times of tuition fees significantly more students did not attend courses as scheduled. Time spent on earning money was significantly increased. 51% of students who had to pay tuition fees and 71% of those who never had to stated tuition fees to be not justified. More than two thirds of students did not recognize any lasting benefit from tuition fees.

CONCLUSION

Tuition fees did not affect discontinuation rate or study duration of Cologne medical students. However, they obviously influenced the study course due to an increased need to pursue a sideline. Cologne medical students rather refused tuition fees and did not recognize their advantages in terms of enhanced quality of studies.

Lack of Gαi2 leads to dilative cardiomyopathy and increased mortality in β1-adrenoceptor overexpressing mice

AIMS

Inhibitory G (Gi) proteins have been proposed to be cardioprotective. We investigated effects of Gαi2 knockout on cardiac function and survival in a murine heart failure model of cardiac β1-adrenoceptor overexpression.

METHODS AND RESULTS

β1-transgenic mice lacking Gαi2 (β1-tg/Gαi2 (-/-)) were compared with wild-type mice and littermates either overexpressing cardiac β1-adrenoceptors (β1-tg) or lacking Gαi2 (Gαi2 (-/-)). At 300 days, mortality of mice only lacking Gαi2 was already higher compared with wild-type or β1-tg, but similar to β1-tg/Gαi2 (-/-), mice. Beyond 300 days, mortality of β1-tg/Gαi2 (-/-) mice was enhanced compared with all other genotypes (mean survival time: 363 ± 21 days). At 300 days of age, echocardiography revealed similar cardiac function of wild-type, β1-tg, and Gαi2 (-/-) mice, but significant impairment for β1-tg/Gαi2 (-/-) mice (e.g. ejection fraction 14 ± 2 vs. 40 ± 4% in wild-type mice). Significantly increased ventricle-to-body weight ratio (0.71 ± 0.06 vs. 0.48 ± 0.02% in wild-type mice), left ventricular size (length 0.82 ± 0.04 vs. 0.66 ± 0.03 cm in wild types), and atrial natriuretic peptide and brain natriuretic peptide expression (mRNA: 2819 and 495% of wild-type mice, respectively) indicated hypertrophy. Gαi3 was significantly up-regulated in Gαi2 knockout mice (protein compared with wild type: 340 ± 90% in Gαi2 (-/-) and 394 ± 80% in β1-tg/Gαi2 (-/-), respectively).

CONCLUSIONS

Gαi2 deficiency combined with cardiac β1-adrenoceptor overexpression strongly impaired survival and cardiac function. At 300 days of age, β1-adrenoceptor overexpression alone had not induced cardiac hypertrophy or dysfunction while there was overt cardiomyopathy in mice additionally lacking Gαi2. We propose an enhanced effect of increased β1-adrenergic drive by the lack of protection via Gαi2. Gαi3 up-regulation was not sufficient to compensate for Gαi2 deficiency, suggesting an isoform-specific or a concentration-dependent mechanism.

"May I help you?" - Evaluation of the new student service at the reception desk during the clinical courses at the Department of Operative Dentistry and Periodontology as a part of a longitudinal curriculum of social and communicative competences for dental students

Objectives: Since 2009, the University of Cologne has been developing a longitudinal curriculum for teaching social and communicative skills to dental students (LSK-Dent) based on the recommendations of the Association for Dental Education in Europe (ADEE). As a part of this curriculum it was considered to develop a reception service in the undergraduate treatment courses of the Department of Operative Dentistry and Periodontology involving the organizational and administrative handling of the patients by the students. Students should gain an insight into everyday practice and the reception service should function as a learning environment for social und communicative competences. This article introduces the LSK-Dent project, the implementation of the reception service and presents initial evaluation results.

Methods: Patients (n=575) and students (n=53) filled out a questionnaire. Additionally, four semi-structured interviews with students were conducted.

Results: The reception service was successfully implemented and endorsed by the students. First indications suggest that the reception service was well received by students as a learning environment for social und communicative competences and viewed as an opportunity to gain an insight into everyday practice.

Conclusion: The reception service is an innovative addition to the treatment courses and an example for transforming an already existing reality in a course into a new learning environment for students. To what extent the implementation of reflexive elements can increase the subjectively perceived additional benefit by students, has to be addressed in further studies.

Lucky guess or knowledge: a cross-sectional study using the Bland and Altman analysis to compare confidence-based testing of pharmacological knowledge in 3rd and 5th year medical students

Multiple-choice-questions are common in medical examinations, but guessing biases assessment results. Confidence-based-testing (CBT) integrates indicated confidence levels. It has been suggested that correctness of and confidence in an answer together indicate knowledge levels thus determining the quality of a resulting decision. We used a CBT approach to investigate whether decision quality improves during undergraduate medical education. 3rd- and 5th-year students attended formative multiple-choice exams on pharmacological issues. Students were asked to indicate their confidence in a given answer. Correctness of answers was scored binary (1-correct; 0-wrong) and confidence levels were transformed to an ordinal scale (guess: 0; rather unsure: 0.33; rather sure: 0.66; very sure: 1). 5th-year students gave more correct answers (73 ± 16 vs. 49 ± 13 %, p < 0.05) and were on average more confident regarding the correctness of their answers (0.61 ± 0.18 vs. 0.46 ± 0.13, p < 0.05). Correlation of these parameters was stronger for 5th-year students (r = 0.81 vs. r = 0.52), but agreement of confidence and correctness ('centration') was lower. By combining the Bland-and-Altman approach with categories of decision-quality we found that 5th-year students were more likely to be 'well-informed' (41 vs. 5 %), while more 3rd-students were 'uninformed' (24 vs. 76 %). Despite a good correlation of exam results and confidence in given answers increased knowledge might be accompanied by a more critical view at the own abilities. Combining the statistical Bland-and-Altman analysis with a theoretical approach to decision-quality, more advanced students are expected to apply correct beliefs, while their younger fellows are rather at risk to hesitate or to act amiss.

Improving adherence with medication: a selective literature review based on the example of hypertension treatment

BACKGROUND

A common problem among patients with chronic diseases is poor adherence with prescribed medication. Studies have shown that certain interventions can improve adherence and clinical outcomes.

METHOD

We selectively searched the PubMed database for publications on the treatment of hypertension that contained the terms "adherence," "drug," "treatment, "outcome," "hypertension," and "randomized controlled trial."

RESULTS

The interventions studied were highly varied, ranging from the use of calendar blister packs to complex patient education programs. 62% of the studies that we identified documented an improvement in adherence after an intervention (median Cohen's d = 0.52). In 92% of cases, improved adherence was associated with a significant improvement in clinical end points (median Cohen's d = 0.34).

CONCLUSION

The promotion of adherence to prescribed medication is clearly desirable. Studies on the treatment of hypertension have shown that attempts to improve adherence often fail. In most studies, however, improved adherence led to better clinical outcomes. Simplification of drug regimens (e.g., reducing the number of pills taken per day) is the single most effective way to promote adherence. Moreover, the findings of studies on the treatment of hypertension and other diseases suggest that shared decision-making should be the basis of physicianpatient discussions about medication. Suitable medications can also be chosen in order to maximize safety and efficacy even if adherence is incomplete. It would also be desirable for studies on the promotion of adherence to be carried out in Germany, under the specific conditions that prevail in our national health-care system.

Spectrum of Cav1.4 dysfunction in congenital stationary night blindness type 2

Defective retinal synaptic transmission in patients affected with congenital stationary night blindness type 2 (CSNB2) can result from different dysfunction phenotypes in Cav1.4 L-type calcium channels. Here we investigated two prototypical Cav1.4 variants from either end of the functional spectrum. Using whole-cell and single-channel patch-clamp techniques, we provide analysis of the biophysical characteristics of the point mutation L860P and the C-terminal truncating mutation R1827X. L860P showed a typical loss-of-function phenotype attributed to a reduced number of functional channels expressed at the plasma membrane as implied by gating current and non-stationary noise analyses. This phenotype can be rationalized, because the inserted proline is predicted to break an amphipatic helix close to the transmembrane segment IIIS1 and thus to reduce channel stability and promote misfolding. In fact, L860P was subject to an increased turnover. In contrast, R1827X displayed an apparent gain-of-function phenotype, i.e., due to a hyperpolarizing shift of the IV-curve and increased single-channel activity. However, truncation also resulted in the loss of functional C-terminal modulation and thus unmasked calcium-dependent inactivation. Thus R1827X failed to support continuous calcium influx. Current inactivation curtails the dynamic range of photoreceptors (e.g., when adapting to variation in illumination). Taken together, the analysis of two representative mutations that occur in CSNB2 patients revealed fundamental differences in the underlying defect. These may explain subtle variations in the clinical manifestation and must be taken into account, if channel function is to be restored by pharmacochaperones or related approaches.

Rare mutations of CACNB2 found in autism spectrum disease-affected families alter calcium channel function

Autism Spectrum Disorders (ASD) are complex neurodevelopmental diseases clinically defined by dysfunction of social interaction. Dysregulation of cellular calcium homeostasis might be involved in ASD pathogenesis, and genes coding for the L-type calcium channel subunits Ca_V1.2 (CACNA1C) and Ca_Vβ2 (CACNB2) were recently identified as risk loci for psychiatric diseases. Here, we present three rare missense mutations of CACNB2 (G167S, S197F, and F240L) found in ASD-affected families, two of them described here for the first time (G167S and F240L). All these mutations affect highly conserved regions while being absent in a sample of ethnically matched controls. We suggest the mutations to be of physiological relevance since they modulate whole-cell Ba²⁺ currents through calcium channels when expressed in a recombinant system (HEK-293 cells). Two mutations displayed significantly decelerated time-dependent inactivation as well as increased sensitivity of voltage-dependent inactivation. In contrast, the third mutation (F240L) showed significantly accelerated time-dependent inactivation. By altering the kinetic parameters, the mutations are reminiscent of the CACNA1C mutation causing Timothy Syndrome, a Mendelian disease presenting with ASD. In conclusion, the results of our first-time biophysical characterization of these three rare CACNB2 missense mutations identified in ASD patients support the hypothesis that calcium channel dysfunction may contribute to autism.

Farm-derived Gram-positive bacterium Staphylococcus sciuri W620 prevents asthma phenotype in HDM- and OVA-exposed mice

BACKGROUND

Farm-derived dust samples have been screened for bacteria with potential allergo-protective properties. Among those was Staphylococcus sciuri W620 (S. sciuri W620), which we tested with regard to its protective capacities in murine models of allergic airway inflammation.

METHODS

We employed two protocols of acute airway inflammation in mice administering either ovalbumin (OVA) or house dust mite extract (HDM) for sensitization. Mechanistic studies on the activation of innate immune responses to S. sciuri W620 were carried out using human primary monocytic dendritic cells (moDC) and co-culture with autologous T cells.

RESULTS

The allergo-protective properties of S. sciuri W620 were proven in a T(H)2-driven OVA model as well as in a mixed T(H)1/T(H)2 phenotype HDM model as demonstrated by abrogation of eosinophils and neutrophils in the airways after intranasal treatment. In the HDM model, lymph node cell T(H)1/T(H)2 signature cytokines were decreased in parallel. Studies on human moDC revealed an activation of TLR2 and NOD2 receptors and initiation of DC maturation following incubation with S. sciuri W620. Cytokine expression analyses after exposure to S. sciuri W620 showed a lack of IL-12 production in moDC due to missing transcription of the IL-12p35 mRNA. However, such DC selectively supported T(H)1 cytokine release by co-cultured T cells.

CONCLUSION AND CLINICAL RELEVANCE

Our proof-of-concept experiments verify the screening system of farm-derived dust samples as suitable to elucidate new candidates for allergo-protection. S. sciuri W620 was shown to possess preventive properties on airway inflammation providing the basis for further mechanistic studies and potential clinical implication.

Pharmacoresistant Cav 2·3 (E-type/R-type) voltage-gated calcium channels influence heart rate dynamics and may contribute to cardiac impulse conduction

Voltage-gated Ca(2+) channels regulate cardiac automaticity, rhythmicity and excitation-contraction coupling. Whereas L-type (Cav 1·2, Cav 1·3) and T-type (Cav 3·1, Cav 3·2) channels are widely accepted for their functional relevance in the heart, the role of Cav 2·3 Ca(2+) channels expressing R-type currents remains to be elucidated. We have investigated heart rate dynamics in control and Cav 2·3-deficient mice using implantable electrocardiogram radiotelemetry and pharmacological injection experiments. Autonomic block revealed that the intrinsic heart rate does not differ between both genotypes. Systemic administration of isoproterenol resulted in a significant reduction in interbeat interval in both genotypes. It remained unaffected after administering propranolol in Cav 2·3(-|-) mice. Heart rate from isolated hearts as well as atrioventricular conduction for both genotypes differed significantly. Additionally, we identified and analysed the developmental expression of two splice variants, i.e. Cav 2·3c and Cav 2·3e. Using patch clamp technology, R-type currents could be detected in isolated prenatal cardiomyocytes and be related to R-type Ca(2+) channels. Our results indicate that on the systemic level, the pharmacologically inducible heart rate range and heart rate reserve are impaired in Cav 2·3 (-|-) mice. In addition, experiments on Langendorff perfused hearts elucidate differences in basic properties between both genotypes. Thus, Cav 2·3 does not only contribute to the cardiac autonomous nervous system but also to intrinsic rhythm propagation.

Effect of MANT-nucleotides on L-type calcium currents in murine cardiomyocytes

Membranous adenylyl cyclases play a major role in G-protein-coupled receptor signalling and regulate various cellular responses, such as cardiac contraction. Cardiac apoptosis and development of cardiac dysfunction is prevented in mice lacking AC 5, a predominant isoform in the heart. In the search for a potent and selective AC 5 inhibitor, we recently identified 2'(3')-methylanthraniloyl-inosine-5'-triphosphate(MANT-ITP) as the most potent AC 5 inhibitor with a K ( i ) of 13 nM. Therefore, AC inhibition of MANT-ITP was assessed in ventricular cardiomyocytes and compared to three other MANT-nucleotides to evaluate its effect on cardiac signalling. Basal and isoproterenol-induced L-type calcium currents (I (Ca,L)) in murine ventricular cardiomyocytes were recorded by whole-cell patch-clamp technique, using four different MANT-nucleotides. The effects of the MANT-nucleotides on I (Ca,L) were unexpectedly complex. All MANT-nucleotides exhibited an inhibitory effect on basal I (Ca,L). Additionally, several MANT-nucleotides, i.e., MANT-ITPγS, MANT-ATP, and MANT-ITP, caused a strong initial increase in basal I (Ca,L) within the first 2.5 min that appeared to be unrelated to AC 5 inhibition. However, we detected a significant reduction on isoproterenol-induced I (Ca,L) with MANT-ITP, supporting the notion that AC 5 plays an important role in agonist-stimulated activation of I (Ca,L). Collectively, MANT-nucleotides are useful tools for the characterization of recombinant ACs, for fluorescence studies and crystallography, but in intact cardiomyocytes, caution must be exerted since MANT-nucleotides apparently possess additional effects than AC 5 inhibition, limiting their usefulness as tools for intact cell studies.

Recommendations for reviewing a manuscript for the GMS Zeitschrift für Medizinische Ausbildung

The aim of this paper, written by the committee of educational research methodology of the "Society for Medical Education" of the German-speaking countries, will give recommendations for the review process of scientific papers in medical education. The recommendations are based on the results of a workshop in 2007 and on a survey among reviewers of the journal GMS Z Med Ausbild. It reflects on international standards and research in medical education in Germany. The paper describes reviewer's function concerning the journal of GMS Z Med Ausbild and specifies criteria for the review process with regard to the editors and reviewers; it also gives proposals for a feedback to the author. The catalogue of criteria for the reviewers is pictured in a checklist. The present recommendations shall help to increase the quality of the review process and to improve the national and international acceptance of the journal GMS Z Med Ausbild. Additionally, transparency of the review processes will support authors to submit a scientific article of high quality.

Structural and biophysical determinants of single Ca(V)3.1 and Ca(V)3.2 T-type calcium channel inhibition by N(2)O

We investigated the biophysical mechanism of inhibition of recombinant T-type calcium channels Ca(V)3.1 and Ca(V)3.2 by nitrous oxide (N(2)O). To identify functionally important channel structures, chimeras with reciprocal exchange of the N-terminal domains I and II and C-terminal domains III and IV were examined. In whole-cell recordings N(2)O significantly inhibited Ca(V)3.2, and - less pronounced - Ca(V)3.1. A Ca(V)3.2-prevalent inhibition of peak currents was also detected in cell-attached multi-channel patches. In cell-attached patches containing < or = 3 channels N(2)O reduced average peak current of Ca(V)3.2 by decreasing open probability and open time duration. Effects on Ca(V)3.1 were smaller and mediated by a reduced fraction of sweeps containing channel activity. Without drug, single Ca(V)3.1 channels were significantly less active than Ca(V)3.2. Chimeras revealed that domains III and IV control basal gating properties. Domains I and II, in particular a histidine residue within Ca(V)3.2 (H191), are responsible for the subtype-prevalent N(2)O inhibition. Our study demonstrates the biophysical (open times, open probability) and structural (domains I and II) basis of action of N(2)O on Ca(V)3.2. Such a fingerprint of single channels can help identifying the molecular nature of native channels. This is exemplified by a characterization of single channels expressed in human hMTC cells as functional homologues of recombinant Ca(V)3.1.

Transgenic simulation of human heart failure-like L-type Ca2+-channels: implications for fibrosis and heart rate in mice

AIMS

Cardiac L-type Ca(2+)-currents show distinct alterations in chronic heart failure, including increased single-channel activity and blunted adrenergic stimulation, but minor changes of whole-cell currents. Expression of L-type Ca(2+)-channel beta(2)-subunits is enhanced in human failing hearts. In order to determine whether prolonged alteration of Ca(2+)-channel gating by beta(2)-subunits contributes to heart failure pathogenesis, we generated and characterized transgenic mice with cardiac overexpression of a beta(2a)-subunit or the pore Ca(v)1.2 or both, respectively.

METHODS AND RESULTS

Four weeks induction of cardiac-specific overexpression of rat beta(2a)-subunits shifted steady-state activation and inactivation of whole-cell currents towards more negative potentials, leading to increased Ca(2+)-current density at more negative test potentials. Activity of single Ca(2+)-channels was increased in myocytes isolated from beta(2a)-transgenic mice. Ca(2+)-current stimulation by 8-Br-cAMP and okadaic acid was blunted in beta(2a)-transgenic myocytes. In vivo investigation revealed hypotension and bradycardia upon Ca(v)1.2-transgene expression but not in mice only overexpressing beta(2a). Double-transgenics showed cardiac arrhythmia. Interstitial fibrosis was aggravated by the beta(2a)-transgene compared with Ca(v)1.2-transgene expression alone. Overt cardiac hypertrophy was not observed in any model.

CONCLUSION

Cardiac overexpression of a Ca(2+)-channel beta(2a)-subunit alone is sufficient to induce Ca(2+)-channel properties characteristic of chronic human heart failure. beta(2a)-overexpression by itself did not induce cardiac hypertrophy or contractile dysfunction, but aggravated the development of arrhythmia and fibrosis in Ca(v)1.2-transgenic mice.

The semi-structured triple jump--a new assessment tool reflects qualifications of tutors in a PBL course on basic pharmacology

In spite of major efforts, there are only a few assessment tools reflecting learning outcomes particularly attributed to problem-based learning (PBL). We aimed to design a more appropriate assessment method by merging elements of the key features and the triple-jump approach. In a prospective, two-phase study, we designed and validated a new assessment tool, called the semi-structured triple jump (sTJ). At the end of a course on basic medical pharmacology, it was performed in addition to a final exam composed of multiple-choice questions. Since in a previous study we had shown tutor expertise to influence students' perception of the learning process, we examined the effect of tutor expertise on results obtained with these assessment tools. We newly developed a questionnaire for student evaluation of the PBL learning process that was validated and tested for reliability. Our aim was to answer two major questions: (1) Does our newly designed assessment tool come up with methodical claims like validity, objectivity and reliability? (2) Does our newly designed assessment tool reflect differences in tutors' expertise? The semi-structured triple jump turned out to be a valid and highly objective assessment tool showing a moderate reliability as found with other triple-jump modifications before. Interestingly, several steps of the sTJ showed a significant correlation to either tutors' subject- or method-matter expertise, respectively. Our data support the approach of supplementing the assessment by structured case-based tools to make it more appropriate for PBL.

Increased expression of the auxiliary beta(2)-subunit of ventricular L-type Ca(2)+ channels leads to single-channel activity characteristic of heart failure

Background

Increased activity of single ventricular L-type Ca²⁺-channels (L-VDCC) is a hallmark in human heart failure. Recent findings suggest differential modulation by several auxiliary β-subunits as a possible explanation.

Methods and Results

By molecular and functional analyses of human and murine ventricles, we find that enhanced L-VDCC activity is accompanied by altered expression pattern of auxiliary L-VDCC β-subunit gene products. In HEK293-cells we show differential modulation of single L-VDCC activity by coexpression of several human cardiac β-subunits: Unlike β₁ or β₃ isoforms, β_2a and β_2b induce a high-activity channel behavior typical of failing myocytes. In accordance, β₂-subunit mRNA and protein are up-regulated in failing human myocardium. In a model of heart failure we find that mice overexpressing the human cardiac Ca_V1.2 also reveal increased single-channel activity and sarcolemmal β₂ expression when entering into the maladaptive stage of heart failure. Interestingly, these animals, when still young and non-failing (“Adaptive Phase”), reveal the opposite phenotype, viz: reduced single-channel activity accompanied by lowered β₂ expression. Additional evidence for the cause-effect relationship between β₂-subunit expression and single L-VDCC activity is provided by newly engineered, double-transgenic mice bearing both constitutive Ca_V1.2 and inducible β₂ cardiac overexpression. Here in non-failing hearts induction of β₂-subunit overexpression mimicked the increase of single L-VDCC activity observed in murine and human chronic heart failure.

Conclusions

Our study presents evidence of the pathobiochemical relevance of β₂-subunits for the electrophysiological phenotype of cardiac L-VDCC and thus provides an explanation for the single L-VDCC gating observed in human and murine heart failure.

Mechanism of Ca(v)1.2 channel modulation by the amino terminus of cardiac beta2-subunits

L-type calcium channels are composed of a pore, alpha1c (Ca(V)1.2), and accessory beta- and alpha2delta-subunits. The beta-subunit core structure was recently resolved at high resolution, providing important information on many functional aspects of channel modulation. In this study we reveal differential novel effects of five beta2-subunits isoforms expressed in human heart (beta(2a-e)) on the single L-type calcium channel current. These splice variants differ only by amino-terminal length and amino acid composition. Single-channel modulation by beta2-subunit isoforms was investigated in HEK293 cells expressing the recombinant L-type ion conducting pore. All beta2-subunits increased open probability, availability, and peak current with a highly consistent rank order (beta2a approximately = beta2b > beta2e approximately = beta2c > beta2d). We show graded modulation of some transition rates within and between deep-closed and inactivated states. The extent of modulation correlates strongly with the length of amino-terminal domains. Two mutant beta2-subunits that imitate the natural span related to length confirm this conclusion. The data show that the length of amino termini is a relevant physiological mechanism for channel closure and inactivation, and that natural alternative splicing exploits this principle for modulation of the gating properties of calcium channels.