Guest Editorial: Perspectives on Megaprojects

Guest Editor: Willie Tan, National University of Singapore

Mass measurements demonstrate a strong N=28 shell gap in argon

We present results from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. We report the first mass measurements of ^{48}Ar and ^{49}Ar and find atomic mass excesses of -22.28(31)  MeV and -17.8(1.1)  MeV, respectively. These masses provide strong evidence for the closed shell nature of neutron number N=28 in argon, which is therefore the lowest even-Z element exhibiting the N=28 closed shell. The resulting trend in binding-energy differences, which probes the strength of the N=28 shell, compares favorably with shell-model calculations in the sd-pf shell using SDPF-U and SDPF-MU Hamiltonians.

Topical axitinib suppresses angiogenesis pathways induced by pulsed dye laser

BACKGROUND

The recurrence of port-wine stain (PWS) blood vessels by pulsed dye laser (PDL)-induced angiogenesis is a critical barrier that must be overcome to achieve a better therapeutic outcome.

OBJECTIVES

To determine whether PDL-induced angiogenesis can be suppressed by topical axitinib.

METHODS

The mRNA expression profiles of 86 angiogenic genes and phosphorylation levels of extracellular signal regulated kinases (ERKs), phosphorylated protein kinase B (AKT) and ribosomal protein S6 kinase (p70S6K) in rodent skin were examined with or without topical axitinib administration after PDL exposure.

RESULTS

The PDL-induced increased transcriptional levels of angiogenic genes peaked at days 3-7 post-PDL exposure. Topical application of 0·5% axitinib effectively suppressed the PDL-induced increase in mRNA levels of the examined angiogenic genes and activation of AKT, P70S6K and ERK from days 1 to 7 post-PDL exposure. After topical administration, axitinib penetrated into rodent skin to an approximate depth of 929·5 μm.

CONCLUSIONS

Topical application of 0·5% axitinib can systematically suppress the PDL-induced early stages of angiogenesis via inhibition of the AKT/mammalian target of rapamycin/p70S6K and Src homology 2 domain containing transforming protein-1/mitogen-activated protein kinase kinase/ERK pathway cascades.

Sustainable financing of rail systems: the case of Singapore

For many years, many governments have tried to find a sustainable way to finance rail systems. Many have failed, for one reason or another. This paper traces the long history of various common modes of financing rail systems and then presents the Singapore model as a case study. Although it is a world-class rail system, the Singapore model still has its faults, and there have been recent attempts to strengthen the system, particularly in its maintenance regime. Importantly, this paper highlights that without a proper financing framework, infrastructure asset management is doomed to fail.

Treatment of tubal pregnancy using comprehensive interventional methods

OBJECTIVE

To investigate the efficacy of combined interventional methods in treatment of tubal pregnancy.

MATERIALS AND METHODS

One hundred sixty-two patients with tubal pregnancy were enrolled in this study. In all patients, the feeding uterine artery at affected side was perfused with methotrexate (MTX), followed by occlusion using gelatin sponge. Nineteen patients were also treated by perfusion of MTX in ovarian artery at affected side which partially participated in blood supply. Seven patients received direct puncture perfusion of MTX under B ultrasound guidance. Four cases received perfusion of MTX through fallopian tube. After surgery, the serum beta-human chorionic gonadotropin (β-HCG) level was regularly detected, and B ultrasound was used to monitor the pelvic mass change. For 33 patients with fertility requirement, hysterosalpingography (HSG) was conducted after menstruation restoration.

RESULTS

Tubal pregnancy was terminated in 160 patients (98.76%), with inefficacy in two patients (1.23%) who were treated by surgery. HSG showed tubal patency in 27 patients. Tubal obstruction was found in the other six patients. After recanalization, three cases were unobstructed, with obstruction in other three cases. Fifteen patients achieved intrauterine pregnancy after six to 17 months from surgery.

CONCLUSIONS

Comprehensive interventional treatment can prevent internal bleeding caused by failure of many conservative treatments, improve the indication and success rate of treatment, and preserve the complete fallopian tube.

The inhibitory effect of melatonin on colonic motility disorders induced by water avoidance stress in rats

OBJECTIVES

Psychological stress is involved in the etiology of functional gastrointestinal disease (FGID). Accumulations of chronic continuous stress associate with the symptoms of the gastrointestinal tract (GIT) including abdominal discomfort, pain, constipation or diarrhea. Melatonin (MT) is a neurohormone which mainly synthesized in the pineal gland and GIT, has been shown to alleviate the stress and regulate the intestinal motility. Although melatonin attenuated abnormal defecation induced by stress, the mechanisms of the effect are not fully elucidated. This study sought to investigate the effect of melatonin (MT) on colonic smooth muscle contractility disorders induced by chronic water avoidance stress (WAS).

MATERIALS AND METHODS

36 adult Wistar rats were divided into three groups [Control+V (vehicle solution), WAS+V, WAS+MT]. The WAS+V and WAS+MT groups were suffered from WAS for one hour daily for 10 days. Melatonin was given 30 min before stress session in the WAS+MT group. Colonic motility was assessed using the numbers of fecal pellet output. The concentrations of melatonin and serotonin (5-HT) were measured through ELISA method. The contractions of isolated colonic strips were assessed through isometric force transducer.

RESULTS

The numbers of fecal output was increased in the WAS+V group, and melatonin attenuates the increased fecal pellet output induced by WAS. The concentrations of 5-HT was increased by WAS, and melatonin decreased the augment in the concentration of 5-HT. In the part of contraction recording of colonic smooth muscle, melatonin inhibited the fortified spontaneous contraction induced by WAS, and decreased the amplitude of spontaneous contraction stimulated by Ach and KCl after WAS treatment.

CONCLUSIONS

Melatonin could inhibit WAS-induced fecal output pellets by inactivating the 5-HT pathway, may interact with calcium channel and inhibit the influx of calcium.

Development of aptamer-based nanomaterials for biological analysis

Aptamers selected from a large random sequence pool are oligonucleic acid or peptide molecules that bind to a specific target molecule with high affinity and sensitivity. Targets range from small molecules to proteins and peptides, even tissue or cells. As such, aptamers have captured the attention of scientists actively developing technologies for diverse biomedical applications. Particularly, when functionalized with nanomaterials, aptamers offer properties for both biomedical and bioanalytical applications. In this review, these features and properties are discussed with particular emphasis on the use of aptamer-based biosensor/detection platforms.