Cardiomyocyte BRAF and type 1 RAF inhibitors promote cardiomyocyte and cardiac hypertrophy in mice in vivo.

The extracellular signal-regulated kinase 1/2 (ERK1/2) cascade promotes cardiomyocyte hypertrophy and is cardioprotective, with the three RAF kinases forming a node for signal integration. Our aims were to determine if BRAF is relevant for human heart failure, whether BRAF promotes cardiomyocyte hypertrophy, and if Type 1 RAF inhibitors developed for cancer (that paradoxically activate ERK1/2 at low concentrations: the 'RAF paradox') may have the same effect. BRAF was up-regulated in heart samples from patients with heart failure compared with normal controls. We assessed the effects of activated BRAF in the heart using mice with tamoxifen-activated Cre for cardiomyocyte-specific knock-in of the activating V600E mutation into the endogenous gene. We used echocardiography to measure cardiac dimensions/function. Cardiomyocyte BRAFV600E induced cardiac hypertrophy within 10 d, resulting in increased ejection fraction and fractional shortening over 6 weeks. This was associated with increased cardiomyocyte size without significant fibrosis, consistent with compensated hypertrophy. The experimental Type 1 RAF inhibitor, SB590885, and/or encorafenib (a RAF inhibitor used clinically) increased ERK1/2 phosphorylation in cardiomyocytes, and promoted hypertrophy, consistent with a 'RAF paradox' effect. Both promoted cardiac hypertrophy in mouse hearts in vivo, with increased cardiomyocyte size and no overt fibrosis. In conclusion, BRAF potentially plays an important role in human failing hearts, activation of BRAF is sufficient to induce hypertrophy, and Type 1 RAF inhibitors promote hypertrophy via the 'RAF paradox'. Cardiac hypertrophy resulting from these interventions was not associated with pathological features, suggesting that Type 1 RAF inhibitors may be useful to boost cardiomyocyte function.

Safety of Propofol Used as a Rescue Agent During Colonoscopy.

GOAL: The goal of this study was to evaluate the safety of propofol when used by gastroenterologists in patients who have an inadequate response to standard sedation (narcotics and benzodiazepines). BACKGROUND: Many patients fail to achieve adequate sedation from narcotics and benzodiazepines during colonoscopy. The administration of propofol for colonoscopy is increasing, although its use by gastroenterologists is controversial. STUDY: We performed a retrospective review of our hospital's colonoscopy records from January 2006 to December 2009 to identify 403 subjects undergoing screening colonoscopies who required propofol (20 to 30 mg every 3 min as needed) because of inadequate response to standard sedation. We also randomly selected 403 controls undergoing screening colonoscopies from the same time period that only required standard sedation. The incidence of adverse effects was then compared. RESULTS: There were no major adverse events in either group. The rates of minor adverse events in the propofol and control group were 0.02 and 0.01, respectively (P=0.56). Adverse effects in the propofol group included: transient hypotension (n=1), nausea/vomiting (n=3), agitation (n=2), and rash (n=1). Adverse effects seen with standard sedation included: transient hypotension (n=2), nausea/vomiting (n=1), and oversedation (n=2). Patients who received propofol were more likely to be younger, had a history of illicit drug use, and a longer procedure time (P<0.05). CONCLUSIONS: Adjunctive propofol administered by gastroenterologist for conscious sedation was not associated with increased incidence of adverse events. It may be of value in patients who do not respond to conventional sedation.

Expression of oestrogen receptor beta isoforms is regulated by transcriptional and post-transcriptional mechanisms.

Although ERs (oestrogen receptors) mediate breast tumour behaviour, the precise role of ERbeta remains unclear. This is mainly because analyses have been complicated by the presence in breast tissue of three ERbeta protein variants (ERbeta1, ERbeta2 and ERbeta5) that derive from differential 3' splicing. We have recently identified the first known mechanisms responsible for the differential control of isoform expression, involving regulation of translation via 5'-UTRs (untranslated regions). In the present study, we have uncovered further complexity involving the influence of multiple promoters and cross-talk between 5'- and 3'-UTRs. We demonstrate that full-length ERbeta mRNAs are transcribed from three separate promoters; two promoters are well-established within the literature, whereas the third represents a novel finding. Each promoter produces transcripts with distinct 5'-UTRs. The differential 3' splicing that produces transcripts coding for the ERbeta isoforms also defines isoform-specific 3'-UTRs. We identified exact 3'-UTR sequences for each isoform, and have shown that alternative polyadenylation sites are used in a cell-type specific manner to produce transcripts with 3'-UTRs of different lengths. Critically, we show that 5'- and 3'-UTRs combine to specify the efficiencies with which individual transcripts are translated, with 3'-UTR length having a key influence. In addition, we demonstrate how 17beta-oestradiol, a key driver of breast cancer development, affects the regulation of ERbeta expression at both transcriptional and translational levels.