F16 Hybrids Derived from Steviol or Isosteviol Are Accumulated in the Mitochondria of Tumor Cells and Overcome Drug Resistance.

Steviol and isosteviol were prepared from the commercially available sweetener stevioside and converted into lipophilic F16 hybrids. Their cytotoxicity was determined in SRB assays and showed to depend on both the substitution pattern of the aromatic substituent as well as on the spacer length. Therefore, compound 25 held an IC50 (A2780) of 180 nM, thus surpassing the activity of comparable rhodamine hybrids. Several of the compounds were also able to overcome drug resistance in the A2780/A2780cis model. Extra staining experiments showed a similar subcellular accumulation pattern of the F16 hybrids as a well-established mitocan, hence proving preferential mitochondrial accumulation but also some other accumulation in other cellular areas.

Efficacy of a computer based discontinuation strategy to reduce PPI prescriptions: a multicenter cluster-randomized controlled trial.

Deprescribing of inappropriate long-term proton pump inhibitors (PPI) is challenging and there is a lack of useful methods for general practitioners to tackle this. The objective of this randomized controlled trial was to evaluate the effectiveness of the electronic decision aid tool arriba-PPI on reduction of long-term PPI intake. Participants (64.5 ± 12.9 years; 54.4% women) with a PPI intake of at least 6 months were randomized to receive either consultation with arriba-PPI from their general practitioner (n = 1256) or treatment as usual (n = 1131). PPI prescriptions were monitored 6 months before, 6 and 12 months after study initiation. In 49.2% of the consultations with arriba-PPI, the general practitioners and their patients made the decision to reduce or discontinue PPI intake. At 6 months, there was a significant reduction by 22.3% (95% CI 18.55 to 25.98; p < 0.0001) of defined daily doses (DDD) of PPI. A reduction of 3.3% (95% CI - 7.18 to + 0.62) was observed in the control group. At 12 months, the reduction of DDD-PPI remained stable in intervention patients (+ 3.5%, 95% CI - 0.99 to + 8.03), whereas control patients showed a reduction of DDD-PPI (- 10.2%, 95% CI - 6.01 to - 14.33). Consultation with arriba-PPI led to reduced prescription rates of PPI in primary care practices. Arriba-PPI can be a helpful tool for general practitioners to start a conversation with their patients about risks of long-term PPI intake, reduction or deprescribing unnecessary PPI medication.

The Finally Rewarding Search for A Cytotoxic Isosteviol Derivative.

Acid hydrolysis of stevioside resulted in a 63% yield of isosteviol (1), which served as a starting material for the preparation of numerous amides. These compounds were tested for cytotoxic activity, employing a panel of human tumor cell lines, and almost all amides were found to be non-cytotoxic. Only the combination of isosteviol, a (homo)-piperazinyl spacer and rhodamine B or rhodamine 101 unit proved to be particularly suitable. These spacered rhodamine conjugates exhibited cytotoxic activity in the sub-micromolar concentration range. In this regard, the homopiperazinyl-spacered derivatives were found to be better than those compounds with piperazinyl spacers, and rhodamine 101 conjugates were more cytotoxic than rhodamine B hybrids.

Physical activity for chronic back pain: qualitative interview study with patients and GPs in German primary care.

BACKGROUND: Chronic back pain (CBP) is common among patients in primary care and is associated with significant personal and socioeconomic burden. Research has shown that physical activity (PA) is one of the most effective therapies to reduce pain; however, for GPs it remains challenging to advise and encourage individuals with CBP to exercise regularly. AIM: To provide insight into the views and experiences of PA in individuals with CBP, along with those of GPs, and to reveal the facilitators and barriers to engaging in, and maintaining, PA. DESIGN AND SETTING: Qualitative semi-structured interviews with individuals with CBP and GPs recruited via the local research practice network (Famprax) in Hessen, western-central Germany between June and December 2021. METHOD: Interviews were coded separately by consensus and analysed thematically. Findings of the two groups (GPs and patients with CBP) were compared and summarised. RESULTS: A total of 14 patients (n = 9 females and n = 5 males) and 12 GPs (n = 5 females and n = 7 males) were interviewed. Opinions and experiences of PA in individuals with CBP were similar both within and across the GP and patient groups. Interviewees expressed their views on internal and external barriers to PA, and provided strategies to address these barriers and concrete recommendations to increase PA. This study revealed a conflicting doctor-patient relationship ranging from paternalistic, to partnership based, to service provision, which could lead to negative perceptions on both sides, such as frustration and stigma. CONCLUSION: To the best of the authors' knowledge, this is the first qualitative study exploring opinion and experience of PA in individuals with CBP and GPs in parallel. This study reveals a complex doctor- patient relationship and provides an important insight to motivation for, and adherence to, PA in individuals with CBP.

Patients' perspectives on a patient-oriented electronic decision support tool to reduce overuse of proton pump inhibitors (arriba-PPI): a qualitative study in primary care.

BACKGROUND: To evaluate patients' perspectives and their experiences with a consultation involving a computer-assisted and patient-centered discontinuation strategy (arriba-PPI tool) as part of a German multicenter study on reducing the prescription of proton pump inhibitors (PPIs). METHODS: Qualitative in-depth telephone interviews on proton pump inhibitors with patients who had received an arriba-PPI tool-based counseling by their general practitioner (GP). A random sample of 30 patients was taken from study participants. Interviews were conducted in 2020 and analyzed using a thematic qualitative text analysis. RESULTS: Although this was meant to be the key to shared decision making with regard to PPI reduction, study participants mostly did not recall the visual features of the tool. However, a few patients remembered them very clearly. Above all, patients appreciated a trustful relationship with the GP as well as comprehensive, individualized counseling. CONCLUSION: Application of the arriba-PPI tool can support the decision process but can also hinder the consultation process if the tool is not properly embedded in the consultation. GPs using the arriba-PPI tool to support the shared decision-making process should consider the patients' and their own expectations on the benefit of the visual representation of the tool.

Mechanisms of epigenetic and cell-type specific regulation of Hey target genes in ES cells and cardiomyocytes.

Hey bHLH transcription factors are critical effectors of Notch signaling. During mammalian heart development they are expressed in atrial and ventricular cardiomyocytes and in the developing endocardium. Hey knockout mice suffer from lethal cardiac defects, such as ventricular septum defects, valve defects and cardiomyopathy. Despite this functional relevance, little is known about the regulation of downstream targets in relevant cell types. The objective of this study was to elucidate the regulatory mechanisms by which Hey proteins affect gene expression in a cell type specific manner. We used an in vitro cardiomyocyte differentiation system with inducible Hey1 or Hey2 expression to study target gene regulation in cardiomyocytes (CM) generated from murine embryonic stem cells (ESC). The effects of Hey1 and Hey2 are largely redundant, but cell type specific. The number of regulated genes is comparable between ESC and CM, but the total number of binding sites is much higher, especially in ESC, targeting mainly genes involved in transcriptional regulation and developmental processes. Repression by Hey proteins generally correlates with the extent of Hey-binding to target promoters, Hdac recruitment and lower histone acetylation. Functionally, treatment with the Hdac inhibitor TSA abolished Hey target gene regulation. However, in CM the repressive effect of Hey-binding is lost for a subset of genes. These also lack Hey-dependent histone deacetylation in CM and are enriched for binding sites of cardiac specific activators like Srf, Nkx2-5, and Gata4. Ectopic Nkx2-5 overexpression in ESC blocks Hey-mediated repression of these genes. Thus, Hey proteins mechanistically repress target genes via Hdac recruitment and histone deacetylation. In CM Hey-repression is counteracted by cardiac activators, which recruit histone acetylases and prevent Hey mediated deacetylation and subsequent repression for a subset of genes.

Gut microbiota of the tick vector Ixodes scapularis modulate colonization of the Lyme disease spirochete.

Arthopods such as Ixodes scapularis ticks serve as vectors for many human pathogens. The arthropod gut presents a pivotal microbial entry point and determines pathogen colonization and survival. We show that the gut microbiota of I. scapularis, a major vector of the Lyme disease spirochete Borrelia burgdorferi, influence spirochete colonization of ticks. Perturbing the gut microbiota of larval ticks reduced Borrelia colonization, and dysbiosed larvae displayed decreased expression of the transcription factor signal transducer and activator of transcription (STAT). Diminished STAT expression corresponded to lower expression of peritrophin, a key glycoprotein scaffold of the glycan-rich mucus-like peritrophic matrix (PM) that separates the gut lumen from the epithelium. The integrity of the I. scapularis PM was essential for B. burgdorferi to efficiently colonize the gut epithelium. These data elucidate a functional link between the gut microbiota, STAT-signaling, and pathogen colonization in the context of the gut epithelial barrier of an arthropod vector.

Target gene analysis by microarrays and chromatin immunoprecipitation identifies HEY proteins as highly redundant bHLH repressors.

HEY bHLH transcription factors have been shown to regulate multiple key steps in cardiovascular development. They can be induced by activated NOTCH receptors, but other upstream stimuli mediated by TGFß and BMP receptors may elicit a similar response. While the basic and helix-loop-helix domains exhibit strong similarity, large parts of the proteins are still unique and may serve divergent functions. The striking overlap of cardiac defects in HEY2 and combined HEY1/HEYL knockout mice suggested that all three HEY genes fulfill overlapping function in target cells. We therefore sought to identify target genes for HEY proteins by microarray expression and ChIPseq analyses in HEK293 cells, cardiomyocytes, and murine hearts. HEY proteins were found to modulate expression of their target gene to a rather limited extent, but with striking functional interchangeability between HEY factors. Chromatin immunoprecipitation revealed a much greater number of potential binding sites that again largely overlap between HEY factors. Binding sites are clustered in the proximal promoter region especially of transcriptional regulators or developmental control genes. Multiple lines of evidence suggest that HEY proteins primarily act as direct transcriptional repressors, while gene activation seems to be due to secondary or indirect effects. Mutagenesis of putative DNA binding residues supports the notion of direct DNA binding. While class B E-box sequences (CACGYG) clearly represent preferred target sequences, there must be additional and more loosely defined modes of DNA binding since many of the target promoters that are efficiently bound by HEY proteins do not contain an E-box motif. These data clearly establish the three HEY bHLH factors as highly redundant transcriptional repressors in vitro and in vivo, which explains the combinatorial action observed in different tissues with overlapping expression.

Physiological notch signaling maintains bone homeostasis via RBPjk and Hey upstream of NFATc1.

Notch signaling between neighboring cells controls many cell fate decisions in metazoans both during embryogenesis and in postnatal life. Previously, we uncovered a critical role for physiological Notch signaling in suppressing osteoblast differentiation in vivo. However, the contribution of individual Notch receptors and the downstream signaling mechanism have not been elucidated. Here we report that removal of Notch2, but not Notch1, from the embryonic limb mesenchyme markedly increased trabecular bone mass in adolescent mice. Deletion of the transcription factor RBPjk, a mediator of all canonical Notch signaling, in the mesenchymal progenitors but not the more mature osteoblast-lineage cells, caused a dramatic high-bone-mass phenotype characterized by increased osteoblast numbers, diminished bone marrow mesenchymal progenitor pool, and rapid age-dependent bone loss. Moreover, mice deficient in Hey1 and HeyL, two target genes of Notch-RBPjk signaling, exhibited high bone mass. Interestingly, Hey1 bound to and suppressed the NFATc1 promoter, and RBPjk deletion increased NFATc1 expression in bone. Finally, pharmacological inhibition of NFAT alleviated the high-bone-mass phenotype caused by RBPjk deletion. Thus, Notch-RBPjk signaling functions in part through Hey1-mediated inhibition of NFATc1 to suppress osteoblastogenesis, contributing to bone homeostasis in vivo.

Hey bHLH factors in cardiovascular development.

The Notch pathway is now firmly established as a key signaling system for embryonic cardiovascular development as well as some adult pathologies in vertebrates. We have identified Hey bHLH transcriptional repressors as critical, but partly redundant transducers of these signals. Hey proteins control cardiomyocyte differentiation, epithelial to mesenchymal transition of endocardial cells, and a number of key features of arterial endothelial cells with corresponding defects in knockout mice. While most of the phenotypes are described in embryonic development, there is increasing evidence for additional adult pathologies. Despite the functional importance of Hey proteins little is still known about their molecular targets and interactions.

TMEM16B, a novel protein with calcium-dependent chloride channel activity, associates with a presynaptic protein complex in photoreceptor terminals.

Photoreceptor ribbon synapses release glutamate in response to graded changes in membrane potential evoked by vast, logarithmically scalable light intensities. Neurotransmitter release is modulated by intracellular calcium levels. Large Ca(2+)-dependent chloride currents are important regulators of synaptic transmission from photoreceptors to second-order neurons; the molecular basis underlying these currents is unclear. We cloned human and mouse TMEM16B, a member of the TMEM16 family of transmembrane proteins, and show that it is abundantly present in the photoreceptor synaptic terminals in mouse retina. TMEM16B colocalizes with adaptor proteins PSD95, VELI3, and MPP4 at the ribbon synapses and contains a consensus PDZ class I binding motif capable of interacting with PDZ domains of PSD95. Furthermore, TMEM16B is lost from photoreceptor membranes of MPP4-deficient mice. This suggests that TMEM16B is a novel component of a presynaptic protein complex recruited to specialized plasma membrane domains of photoreceptors. TMEM16B confers Ca(2+)-dependent chloride currents when overexpressed in mammalian cells as measured by halide sensitive fluorescent protein assays and whole-cell patch-clamp recordings. The compartmentalized localization and the electrophysiological properties suggest TMEM16B to be a strong candidate for the long sought-after Ca(2+)-dependent chloride channel in the photoreceptor synapse.