Splicing factor SRSF3 represses the translation of programmed cell death 4 mRNA by associating with the 5'-UTR region

Serine/arginine-rich splicing factor 3 (SRSF3), a member of the serine/arginine (SR)-rich family of proteins, regulates both alternative splicing of pre-mRNA and export of mature mRNA from the nucleus. Although its role in nuclear mRNA processing is well understood, the mechanism by which it alters the fate of cytoplasmic mRNA molecules remains elusive. Here, we provide evidence that SRSF3 not only regulates the alternative splicing pattern of programmed cell death 4 (PDCD4) mRNA, but also modulates its translational efficiency in the cytoplasm by lowering translation levels. We observed a marked increase in PDCD4 mRNA in translating polysome fractions upon silencing of SRSF3, and, conversely, ectopic overexpression of SRSF3 shifted PDCD4 mRNA into non-translating ribosomal fractions. In live cells, SRSF3 colocalized with PDCD4 mRNA in P-bodies (PBs), where translationally silenced mRNAs are deposited, and this localization was abrogated upon SRSF3 silencing. Furthermore, using two different reporter systems, we showed that SRSF3 interacts directly with PDCD4 mRNA and mediates translational repression by binding to the 5'-untranslated region (5'-UTR). In summary, our data suggest that the oncogenic potential of SRSF3 might be realized, in part, through the translational repression of PDCD4 mRNA.

Slewing Mirror Telescope optics for the early observation of UV/optical photons from Gamma-Ray Bursts

We report on design, manufacture, and testing of a Slewing Mirror Telescope (SMT), the first of its kind and a part of Ultra-Fast Flash Observatory-pathfinder (UFFO-p) for space-based prompt measurement of early UV/optical light curves from Gamma-Ray Bursts (GRBs). Using a fast slewing mirror of 150 mm diameter mounted on a 2 axis gimbal stage, SMT can deliver the images of GRB optical counterparts to the intensified CCD detector within 1.5~1.8 s over ± 35 degrees in the slewing field of view. Its Ritchey-Chrétien telescope of 100 mm diameter provides a 17 × 17 arcmin² instantaneous field of view. Technical details of design, construction, the laboratory performance tests in space environments for this unique SMT are described in conjunction with the plan for in-orbit operation onboard the Lomonosov satellite in 2013.

Porcine feasibility and safety study of a new paclitaxel-eluting biliary stent with a Pluronic-containing membrane

BACKGROUND AND STUDY AIM

Metal stents for malignant biliary obstruction are susceptible to occlusion by tumor ingrowth or overgrowth. Therefore, we previously reported our use of a metal stent covered with a paclitaxel-incorporated membrane giving an antitumor effect to prevent occlusion from tumor ingrowth. We have also developed a new generation of paclitaxel-eluting biliary stent using a membrane containing Pluronic F-127 for effective drug delivery. The aim of this study was to investigate the safety and efficacy of drug delivery for this newly developed stent in the biliary tract.

METHODS

Metal stents were coated with paclitaxel and various concentrations of Pluronic F-127 in phosphate-buffered saline solution. Stents containing varying concentrations were placed in the bile ducts of eight pigs divided as follows: group I, 0% Pluronic + 0% paclitaxel; group II, 0% Pluronic + 10% paclitaxel; group III, 10% Pluronic + 10% paclitaxel; group IV, 20% Pluronic + 10% paclitaxel. The histology of the porcine bile duct and the amount of paclitaxel in the porcine serum were examined. The amount of paclitaxel released was also measured in vitro.

RESULTS

Histologic changes in the porcine biliary epithelium were acceptable in terms of safety, based on inflammatory cell infiltration and fibrotic reaction. No significant differences in histology were observed between the groups. In the porcine serum analysis, released paclitaxel was detected for 28 days with the 10% Pluronic concentration (group III). However, released paclitaxel was observed for only 7 days in groups II and IV. In the in vitro experiments, long-lasting release of paclitaxel was also noted from the stent with 10% Pluronic.

CONCLUSIONS

The new paclitaxel-eluting stent with 10% Pluronic F-127 is safe and provides enhanced local drug delivery.

Increase of paradoxical excitement response during propofol-induced sedation in hazardous and harmful alcohol drinkers

BACKGROUND

Paradoxical excitement response during sedation consists of loss of affective control and abnormal movements. Chronic alcohol abuse has been proposed as a predisposing factor despite lack of supporting evidence. Because alcohol and propofol have a common site of action, we postulated that paradoxical excitement responses during propofol-induced sedation occur more frequently in hazardous and harmful alcohol drinkers than in social or non-drinkers.

METHODS

One hundred and ninety patients undergoing orthopaedic knee joint surgery were enrolled in this prospective and observational study. Subjects were divided into Group HD (hazardous and harmful drinkers) or Group NHD (no hazardous drinkers) according to the alcohol use disorder identification test (AUDIT). In study 1, propofol infusion was adjusted to achieve the bispectral index at 70-80 using target-controlled infusion. In study 2, the target concentration of propofol was fixed at 0.8 (study 2/Low) or 1.4 μg ml(-1) (study 2/High). Paradoxical excitement responses were categorized by intensity into mild, moderate, or severe.

RESULTS

The overall incidence of paradoxical excitement response was higher in Group HD than in Group NHD in study 1 (71.4% vs 43.8%; P=0.022) and study 2/High (70.0% vs 34.5%; P=0.006) but not in study 2/Low. The incidence of moderate-to-severe response was significantly higher in Group HD of study 1 (28.6% vs 3.1%; P=0.0005) and study 2/High (23.3% vs 3.4%; P=0.029) with no difference in study 2/Low. Severe excitement response occurred only in Group HD of study 1 and study 2/High.

CONCLUSIONS

Paradoxical excitement occurred more frequently and severely in hazardous and harmful alcohol drinkers than in social drinkers during propofol-induced moderate-to-deep sedation, but not during light sedation.

Contrast-enhanced computed tomography angiography and volume-rendered imaging for evaluation of cellophane banding in a dog with extrahepatic portosystemic shunt

A 4-year-old, 1.8 kg, male, castrated Maltese was presented for evaluation of urolithiasis. Urinary calculi were composed of ammonium biurate. Preprandial and postprandial bile acids were 44.2 and 187.3 μmol/ , respectively (reference ranges 0–10 and 0–20 μmol/ , respectively). Single-phase contrast-enhanced computed tomography angiography (CTA) with volume-rendered imaging (VRI) was obtained. VRI revealed a portocaval shunt originating just cranial to a tributary of the gastroduodenal vein and draining into the caudal vena cava at the level of the epiploic foramen. CTA revealed a 3.66 mm-diameter shunt measured at the level of the termination of the shunt and a 3.79 mm-diameter portal vein measured at the level between the origin of the shunt and the porta of the liver. Surgery was performed using cellophane banding without attenuation. Follow-up single-phase CTA with VRI was obtained 10 weeks after surgery. VRI revealed no evidence of portosystemic communication on the level of a cellophane band and caudal to the cellophane band. CTA demonstrated an increased portal vein diameter (3.79–5.27 mm) measured at the level between the origin of the shunt and the porta of the liver. Preprandial and postprandial bile acids were 25 and 12.5 μmol/ , respectively (aforementioned respective reference ranges), 3 months post-surgery. No problems were evident at 6 months.