1,410 research outputs found
A Principles-Based Response to the Proposed Reform of the Governance Structure for Listing Regulation in Hong Kong
The June 2016 joint consultation on listing regulation arises out of a renewed concern to ensure the Hong Kong market remains fit for purpose in meeting current and emergent challenges and demands. This paper undertakes an analysis of the consultation applying a law and principles based approach. This approach requires the listing regime to be suitable not only in view of market conditions but also in view of internationally accepted practices and standards concerning regulatory oversight. While it is recognized that regulatory evolution requires progressive innovation, the two new SEHK sub-committees envisaged by the joint consultation give rise to several areas of concern. The reasons for implementing the changes proposed are not well explained in the consultation and no clear case is presented as to why the sub-committee structure would provide improvements. Putting the SFC into a frontline decision-making role is problematic under the current statutory framework, and is not necessarily a forward moving step toward a system of statutory listing regulation. It implements changes that bypass legislative intent and renders certain statutory laws meaningless, it may subject the SFC to corporate laws that would impact on its ability to act as an independent regulator, and it would diminish regulatory accountability and clarity. The risk that the changes could be regarded as legislation by regulation would weaken, not strengthen, the SFC’s regulatory mandate over public listings. These problems run counter to the intent of the Proposal to improve listing regulation and carry the risk that Hong Kong’s governance of listings, particularly the role of the statutory regulator in it, would be at odds with international best practices. The conclusion of this paper is that progressing with the sub-committee proposal would not be a positive development unless and until the issues identified in this paper are properly addressed and resolved. It is suggested that a more holistic view of market development needs to be adopted that extends beyond the decision making mechanisms of the dual filing regime and identifies more precisely the specific issues that are problematic. Doing so would permit more targeted and sustainable oversight mechanisms to be developed.postprin
Moving Forward on Listing Reform
This paper considers the process of listing reform in Hong Kong. It identifies the primary underlying threads in that process as undertaken to date and queries whether the overarching strategic objectives for market development have been adequately diagnosed. Exchanges compete on a range of factors that are influenced by both public and private interests, which requires a clear policy analysis of developmental objectives as a precursor to regulatory reform proposals. Three Propositions are derived that may assist to reposition the reform debate. It is suggested that if stakeholders take these Propositions on board in earnest, there will be a better prospect for moving forward together on listing reform.published_or_final_versio
Cisplatin and Oxaliplatin Toxicity: Importance of Cochlear Kinetics as a Determinant for Ototoxicity
Background
Cisplatin is a commonly used platinum anti-cancer drug. Regrettably cisplatin
has dose-limiting ototoxic side effects, e.g. the drug can induce an irreversible
hearing loss. The ototoxic mechanisms of cisplatin have not been
elucidated in the human ear and no clinically useful oto-protectors are yet
available. Cisplatin is a necessary part of many treatment regimes. Its beneficial
therapeutic effects might be reduced if cisplatin was excluded from the
treatment in order to protect the hearing function. In this work the ototoxic
effects of cisplatin are studied with the aim to better understand the mechanisms
behind the irreversible hearing loss induced by this drug. Oxaliplatin is
a second generation platinum-derivative anti-cancer drug, free from ototoxic
side effects in clinical practice. The effects of oxaliplatin on the inner ear have
been studied in this work and the results are compared with cisplatin treatment.
The two drugs differ regarding both anti-cancer effects and side effects,
which could be attributed to differences in pharmacokinetic factors, cellular
uptake and apoptotic mechanisms. The thioredoxin redox system with the
enzyme thioredoxin reductase (TrxR) was studied in cochleae due to a suggested
DNA-independent apoptotic mechanism of the hair cells. The cochlear
pharmacokinetics of cisplatin was assessed and the transport protein organic
cation transporter 2 (OCT2) was studied in relation to the ototoxic effect of
cisplatin.
Material and methods
Cultured human colon carcinoma cells and cell cultures of rat organ of Corti
were used for apoptosis studies in vitro following exposure to cisplatin and
oxaliplatin. Cisplatin and oxaliplatin were administered i.v. to guinea pigs,
followed by in vivo sampling of blood, cerebrospinal fluid (CSF) and scala
tympani (ST) perilymph. Liquid chromatography with post-column derivatization
was used to determine the concentration of parent drug in the samples.
Electrophysiological hearing thresholds and the loss of hair cells were assessed
to evaluate their ototoxic effects. Phenformin, a potential blocker of
OCT2 was administered and the ototoxic side effect of cisplatin was evaluated.
For immunohistochemical studies, cochlea from rat, guinea pig and pig
were used, where TrxR and OCT2 were evaluated in the cochlea. TrxR-assays
were used to measure the TrxR activity in cochlear tissue, both in vivo and in
vitro.
Results
The results from the in vitro studies showed that addition of either cisplatin
or oxaliplatin to the culture medium in organ of Corti cell cultures caused a
similar amount of outer hair cell loss and inhibition of TrxR activity. Cisplatin
exposure to cultured human colon carcinoma cells also reduced the activity
of TrxR. The results from the in vivo studies showed that a considerable concentration
of cisplatin was present in ST perilymph as compared with weak
concentrations of oxaliplatin after high dose oxaliplatin i.v. Ten minutes after
cisplatin administration, its concentration in ST perilymph was 4-fold higher
in the basal turn of the cochlea as compared to the apex. Cisplatin could be
analysed in ST perilymph for up to 120 min. Phenformin i.v. did not reduce
the ototoxic side-effect of cisplatin. Positive immunoreactivity to TrxR was
evident in both hair cells and spiral ganglion cells. Futhermore, OCT2 was
expressed in the supporting cells of organ of Corti and in the spiral ganglion
cells.
Conclusion
The transport of cisplatin to the vulnerable cells of hearing seems to be of major
importance for the ototoxic effects. An early high concentration of cisplatin
in the base of the cochlea and delayed elimination of cisplatin from ST perilymph
may be related to the cisplatin-induced loss of outer hair cells in the
basal turn of the cochlea. Cisplatin and oxaliplatin both cause similar ototoxic
effects when the organ of Corti is directly exposed in vitro. The thioredoxin
redox system with the TrxR enzyme may well play a critical role in cisplatininduced
ototoxicity. The presence of OCT2 in the supporting cells indicates
that this transport protein is primarily not involved in the uptake of cisplatin
from the systemic circulation but rather from the deeper compartments of
the cochlea. The knowledge elicited in this work will hopefully suggest objectives
for further studies in order to develop oto-protective treatments to
preserve the hearing of cisplatin treated patients
Free fatty acids link metabolism and regulation of the insulin-sensitizing fibroblast growth factor-21
OBJECTIVE—Fibroblast growth factor (FGF)-21 improves insulin
sensitivity and lipid metabolism in obese or diabetic animal
models, while human studies revealed increased FGF-21 levels in obesity and type 2 diabetes. Given that FGF-21 has been suggested to be a peroxisome proliferator–activator receptor (PPAR) –dependent regulator of fasting metabolism, we hypothesized that free fatty acids (FFAs), natural agonists of PPAR, might modify FGF-21 levels.
RESEARCH DESIGN AND METHODS—The effect of fatty
acids on FGF-21 was investigated in vitro in HepG2 cells. Within a randomized controlled trial, the effects of elevated FFAs were studied in 21 healthy subjects (13 women and 8 men). Within a clinical trial including 17 individuals, the effect of insulin was analyzed using an hyperinsulinemic-euglycemic clamp and the effect of PPAR activation was studied subsequently in a rosiglitazone
treatment trial over 8 weeks.
RESULTS—Oleate and linoleate increased FGF-21 expression
and secretion in a PPAR-dependent fashion, as demonstrated
by small-interfering RNA–induced PPAR knockdown, while
palmitate had no effect. In vivo, lipid infusion induced an
increase of circulating FGF-21 in humans, and a strong correlation between the change in FGF-21 levels and the change in FFAs was observed. An artificial hyperinsulinemia, which was induced to delineate the potential interaction between elevated FFAs and
hyperinsulinemia, revealed that hyperinsulinemia also increased FGF-21 levels in vivo, while rosiglitazone treatment had no effect.
CONCLUSIONS—The results presented here offer a mechanism
explaining the induction of the metabolic regulator FGF-21 in the fasting situation but also in type 2 diabetes and obesity
Fragment-based discovery of a regulatory site in thioredoxin glutathione reductase acting as "doorstop" for NADPH entry
Members of the FAD/NAD-linked reductase family are recognized as crucial targets in drug development for cancers, inflammatory disorders, and infectious diseases. However, individual FAD/NAD reductases are difficult to inhibit in a selective manner with off target inhibition reducing usefulness of identified compounds. Thioredoxin glutathione reductase (TGR), a high molecular weight thioredoxin reductase-like enzyme, has emerged as a promising drug target for the treatment of schistosomiasis, a parasitosis afflicting more than 200 million people. Taking advantage of small molecules selected from a high-throughput screen and using X-ray crystallography, functional assays, and docking studies, we identify a critical secondary site of the enzyme. Compounds binding at this site interfere with well-known and conserved conformational changes associated with NADPH reduction, acting as a doorstop for cofactor entry. They selectivity inhibit TGR from Schistosoma mansoni and are active against parasites in culture. Since many members of the FAD/NAD-linked reductase family have similar catalytic mechanisms the unique mechanism of inhibition identified in this study for TGR broadly opens new routes to selectively inhibit homologous enzymes of central importance in numerous diseases
Plexin D1 determines body fat distribution by regulating the type V collagen microenvironment in visceral adipose tissue
Proceedings of the National Academy of Sciences of the United States of America112144363-436
PINTA: a web server for network-based gene prioritization from expression data
PINTA (available at http://www.esat.kuleuven.be/pinta/; this web site is free and open to all users and there is no login requirement) is a web resource for the prioritization of candidate genes based on the differential expression of their neighborhood in a genome-wide protein–protein interaction network. Our strategy is meant for biological and medical researchers aiming at identifying novel disease genes using disease specific expression data. PINTA supports both candidate gene prioritization (starting from a user defined set of candidate genes) as well as genome-wide gene prioritization and is available for five species (human, mouse, rat, worm and yeast). As input data, PINTA only requires disease specific expression data, whereas various platforms (e.g. Affymetrix) are supported. As a result, PINTA computes a gene ranking and presents the results as a table that can easily be browsed and downloaded by the user
TcSNP: a database of genetic variation in Trypanosoma cruzi
The TcSNP database (http://snps.tcruzi.org) integrates information on genetic variation (polymorphisms and mutations) for different stocks, strains and isolates of Trypanosoma cruzi, the causative agent of Chagas disease. The database incorporates sequences (genes from the T. cruzi reference genome, mRNAs, ESTs and genomic sequences); multiple sequence alignments obtained from these sequences; and single-nucleotide polymorphisms and small indels identified by scanning these multiple sequence alignments. Information in TcSNP can be readily interrogated to arrive at gene sets, or SNP sets of interest based on a number of attributes. Sequence similarity searches using BLAST are also supported. This first release of TcSNP contains nearly 170 000 high-confidence candidate SNPs, derived from the analysis of annotated coding sequences. As new sequence data become available, TcSNP will incorporate these data, mapping new candidate SNPs onto the reference genome sequences
Human neuropeptide Y signal peptide gain-of-function polymorphism is associated with increased body mass index: possible mode of function
Neuropeptide Y (NPY) has been implicated in the control of food intake and energy balance based on many observations in animals. We have studied single nucleotide polymorphisms (SNPs) within the regulatory and coding sequences of the human NPY gene. One variant (1128 T>C), which causes an amino acid change from leucine to proline at codon 7 in the signal peptide of NPY, was associated with increased body mass index (BMI) in two separate Swedish populations of normal and overweight individuals. In vitro transcription and translation studies indicated the unlikelihood that this signal peptide variation affects the site of cleavage and targeting or uptake of NPY into the endoplasmic reticulum (ER). However, the mutant, and to a lesser extent the wild-type, signal peptide by themselves markedly potentiated NPY-induced food intake, as well as hypothalamic NPY receptor signaling. Our findings in humans strongly indicate that the NPY signaling system is implicated in body weight regulation and suggest a new and unexpected functional role of a signal peptide
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