Treatment of pulmonary arterial hypertension in congenital heart disease in Singapore versus the Netherlands: age exceeds ethnicity in influencing clinical outcome

Background

Advanced treatment of pulmonary arterial hypertension (PAH) in congenital heart disease (CHD) is increasingly applied worldwide following the—mainly Western world based—international PAH-CHD guidelines. However, studies comparing clinical presentation and outcome after the initiation of PAH-specific treatment are lacking. We aimed to analyse this in a Singaporean and Dutch cohort of PAH-CHD patients.

Methods

Adult CHD patients starting PAH-specific therapy, enrolled in two nationwide registries, were analysed. Patients received phosphodiesterase-type-5 inhibitors, endothelin receptor antagonists, or a combination. Change in six-minute walk test (6MWT) during follow-up was analysed using linear mixed model analysis. Determinants for mortality were assessed using Cox proportional hazard analyses.

Results

A total of 74 patients, 45 Dutch (mean age 47?±?14 years) and 29 Singaporean (mean age 41?±?14 years) were analysed. Despite a lower 6MWT (312 versus 395 metres, p?=?0.01) and peak VO₂ (35 versus 49?% of predicted, p?=?0.01) at baseline in Singaporean patients, the treatment effect was similar in the two populations. Age at initiation of therapy (per 5 year lower age, β?=?+?4.5, p?=?0.017) was the strongest predictor of improvement in exercise capacity, corrected for ethnicity, baseline 6MWT, sex and CHD defect.

Conclusions

Patients from Singapore had a worse clinical performance at baseline compared with the PAH-CHD patients from the Netherlands. No relation between ethnicity and improvement in 6MWT after PAH-specific therapy was found. Age at initiation of PAH-specific therapy was the strongest predictor of treatment efficacy and mortality, emphasising the need for early initiation of treatment in these patients.

     

Does the Axillary Lymph Node Ratio Have Any Added Prognostic Value over pN Staging for South East Asian Breast Cancer Patients?

Introduction

Lymph node ratio (LNR, i.e. the ratio of the number of positive nodes to the total number of nodes excised) is reported to be superior to the absolute number of nodes involved (pN stage) in classifying patients at high versus low risk of death following breast cancer. The added prognostic value of LNR over pN in addition to other prognostic factors has never been assessed.

Methods

All patients diagnosed with lymph node positive, non-metastatic invasive breast cancer at the National University Hospital (Singapore) and University of Malaya Medical Center (Kuala Lumpur) between 1990–2007 were included (n = 1589). Overall survival of the patients was estimated by the Kaplan Meier method for LNR [categorized as low (>0 and <0.2), intermediate (0.2–0.65) and high (>0.65–1)] and pN staging [pN1, pN2 and pN3]. Adjusted overall relative mortality risks associated with LNR and pN were calculated by Cox regression. The added prognostic value of LNR over pN was evaluated by comparing the discriminating capacity (as indicated by the c statistic) of two multivariate models, one including pN and one including LNR.

Results

LNR was superior to pN in categorizing mortality risks for women ≥60 years, those with ER negative or grade 3 tumors. In combination with other factors (i.e. age, treatment, grade, tumor size and receptor status), substituting pN by LNR did not result in better discrimination of women at high versus low risk of death, neither for the entire cohort (c statistic 0.72 [0.70–0.75] and 0.73 [0.71–0.76] respectively for pN versus LNR), nor for the subgroups mentioned above.

Conclusion

In combination with other prognosticators, substitution of pN by LNR did not provide any added prognostic value for South East Asian breast cancer patients.     

alpha-Synuclein membrane interactions and lipid specificity

With the discovery of missense mutations (A53T and A30P) in alpha-synuclein (alpha-Syn) in several families with early onset familial Parkinson's disease, alpha-Syn aggregation and fibril formation have been thought to play a role in the pathogenesis of alpha-synucleinopathies, such as Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. As previous reports have suggested that alpha-Syn plays a role in lipid transport and synaptic membrane biogenesis, we investigated whether alpha-Syn binds to a specific lipid ligand using thin layer chromatography overlay and examined the changes in its secondary structure using circular dichroism spectroscopy. alpha-Syn was found to bind to acidic phospholipid vesicles and this binding was significantly augmented by the presence of phosphatidylethanolamine, a neutral phospholipid. We further examined the interaction of alpha-Syn with lipids by in situ atomic force microscopy. The association of soluble wild-type alpha-Syn with planar lipid bilayers resulted in extensive bilayer disruption and the formation of amorphous aggregates and small fibrils. The A53T mutant alpha-Syn disrupted the lipid bilayers in a similar fashion but at a slower rate. These results suggest that alpha-Syn membrane interactions are physiologically important and the lipid composition of the cellular membranes may affect these interactions in vivo.     

Parasites of Pleurobrachia pileus Muller, 1776 (Ctenophora), from Galway Bay, western Ireland

Specimens of Pleurobrachia pileus Müller from Galway Bay,western Ireland, were found to be parasitised by three trematodes,one isopod and one nematode. Among these, the trematode, Opechonabacillaris Molin and didymozoid larvae were the most abundant,infecting over 17% of the Pleurobrachia population. Peak infectionwas during the summer of each year when >40% of P. - pileuswere parasitised. Serious infection was found to be either accompaniedor followed by a sharp decline in the abundance of the ctenophore.A close, but negative, correlation was established between theabundance of P. pileus and the percentage of parasitic infection.The percentage of infection in larger P. pileus was higher thanin small specimens. No parasites were detected from P. pileus1 mm or less in length.     

Evidence that epidermal growth factor is present in swiftlet's (Collocalia) nest

1. An epidermal growth factor (EGF)-like activity was detected and partially purified from swiftlet's nest extract. 2. The partially purified EGF-like activity was able to (a) generate competitive binding curves parallel to the standard curves in radioreceptor assay and (b) stimulate thymidine incorporation in quiescent culture of 3T3 fibroblasts and the latter activity can be suppressed by mouse EGF antibody. 3. Partial characterization of the EGF-like activity in terms of pI, molecular weight and its behavior on gel filtration column suggest that it bears similar physical properties to the EGFs isolated from the mouse and the shrew.     

The role of circulating serotonin in the development of chronic obstructive pulmonary disease

Background

Cigarette smoking is a major risk factor in the development of age-related chronic obstructive pulmonary disease (COPD). The serotonin transporter (SERT) gene polymorphism has been reported to be associated with COPD, and the degree of cigarette smoking has been shown to be a significant mediator in this relationship. The interrelation between circulating serotonin (5-hydroxytyptamine, 5-HT), cigarette smoking and COPD is however largely unknown. The current study aimed at investigating the mediation effects of plasma 5-HT on cigarette smoking-induced COPD and the relation between plasma 5-HT levels and age.

Methods

The association between plasma 5-HT, age and COPD was analyzed in a total of 62 COPD patients (ever-smokers) and 117 control subjects (healthy non-smokers and ever-smokers). Plasma 5-HT levels were measured by enzyme-linked immuno assay (EIA).

Results

The elevated plasma 5-HT levels were significantly associated with increased odds for COPD (OR = 1.221, 95% CI = 1.123 to 1.319, p<0.0001). The effect remained significant after being adjusted for age and pack-years smoked (OR = 1.271, 95% CI = 1.134 to 1.408, p = 0.0003). Furthermore, plasma 5-HT was found to mediate the relation between pack-years smoked and COPD. A positive correlation (r = 0.303, p = 0.017) was found between plasma 5-HT levels and age in COPD, but not in the control subjects (r = −0.149, p = 0.108).

Conclusion

Our results suggest that cigarette smoke-induced COPD is partially mediated by the plasma levels of 5-HT, and that these become elevated with increased age in COPD. The elevated plasma 5-HT levels in COPD might contribute to the pathogenesis of this disease.     

Molecular Evidence for the Hybrid Origin of Bauhinia blakeana （Caesalpinioideae）

Bauhinia blakeana Dunn is the Hong Kong Special Administrative Region emblem and a popular horticultural species in many Asian countries. It was first described as a new species from Hong Kong almost a century ago. This plant is sterile and has long been considered a hybrid, possibly from two related species, B. purpurea and B. variegata. However, not much evidence based on molecular methods was available to support this hypothesis. In this study, sequences of internal transcribed spacer I （ITS1）, rbcL and atpB-rbcL intergenic spacer for five Bauhinia species and two varieties of one of the species were determined and compared. There were two types of ITS1 sequences in B. blakeana, one indistinguishable from that of B. purpurea and the other one identical to that of B. variegata. This confirmed that B. blakeana was a hybrid of these two species. Chloroplast atpB-rbcL intergenic spacer sequence of B. blakeana was identical to that of B. purpurea, indicating that B. purpurea was the female parent. The hybridization event seemed to occur only recently and was a rare incident. Its occurrence was likely facilitated by interspecific pollen competition. It appeared that human efforts played a crucial role in the preservation and ubiquity of B. blakeana.     

Identification of a disruptor of the MDM2-p53 protein–protein interaction facilitated by high-throughput in silico docking

NSC 333003 has been identified from the NCI Diversity Set as an inhibitor of the MDM2-p53 protein–protein interaction by in silico docking (virtual screening). Its potency and chemical characteristics render it well suited for lead optimization studies that can result in more potent analogs with improved drug-like properties. Its synthesis was achieved using an acid catalyzed condensation reaction from commercially available benzothiazole hydrazine and pyridyl phenyl ketone in refluxing methanol. Stereochemical implications for this compound are described.     

1,N6-etheno-2-aza-adenosine 3',5'-monophosphate: a new fluorescent substrate for cycle nucleotide phosphodiesterase

1,N⁶-etheno-2-aza-adenosine 3′,5′-monophosphate (cyclic 2-aza-?-AMP) has been shown to be a sensitive and an efficient substrate for the assay of cyclic-nucleotide phosphodiesterase. The relative activity is 75% compared to cyclic AMP. Two K_m values of 503 and 15 μm were observed with the beef heart enzyme.     

Roles of the Structural Symbiosis Polysaccharide (syp) Genes in Host Colonization,Biofilm Formation,and Polysaccharide Biosynthesis in Vibrio fischeri

The symbiosis polysaccharide locus, syp, is required for Vibrio fischeri to form a symbiotic association with the squid Euprymna scolopes. It is also required for biofilm formation induced by the unlinked regulator RscS. The syp locus includes 18 genes that can be classified into four groups based on putative function: 4 genes encode putative regulators, 6 encode glycosyltransferases, 2 encode export proteins, and the remaining 6 encode proteins with other functions, including polysaccharide modification. To understand the roles of each of the 14 structural syp genes in colonization and biofilm formation, we generated nonpolar in-frame deletions of each gene. All of the deletion mutants exhibited defects in their ability to colonize juvenile squid, although the impact of the loss of SypB or SypI was modest. Consistent with their requirement for colonization, most of the structural genes were also required for RscS-induced biofilm formation. In particular, the production of wrinkled colonies, pellicles, and the matrix on the colony surface was eliminated or severely decreased in all mutants except for the sypB and sypI mutants; in contrast, only a subset of genes appeared to play a role in attachment to glass. Finally, immunoblotting data suggested that the structural Syp proteins are involved in polysaccharide production and/or export. These results provide important insights into the requirements for the syp genes under different environmental conditions and thus lay the groundwork for a more complete understanding of the matrix produced by V. fischeri to enhance cell-cell interactions and promote symbiotic colonization.