Fluorescence anisotropy using highly polarized emitting dyes confined inside BNNTs

Polarized fluorescence emission of nanoscale emitters has been extensively studied for applications such as bioimaging, displays, and optical communication. Extending the polarization properties in large assemblies of compact emitters is, however, challenging because of self-aggregation processes, which can induce depolarization effects, quenching, and cancellations of molecular dipoles. Here we use α-sexithiophene (6T) molecules confined inside boron nitride nanotubes (6T@BNNTs) to induce fluorescence anisotropy in a transparent host. The experiments first indicate that individual 6T@BNNTs exhibit a high polarization extinction ratio, up to 700, at room temperature. Using aberration-corrected HRTEM, we show that the fluorescence anisotropy is consistent with a general alignment of encapsulated 6T molecules along the nanotube axis. The molecular alignment is weakly influenced by the nanotube diameter, a phenomenon ascribed to stronger molecule-to-sidewall interactions compared to intermolecular interactions. By stretching a flexible thin film made of transparent polymers mixed with 6T@BNNTs, we induce a macroscopic fluorescence anisotropy within the film. This work demonstrates that the dyes@BNNT system can be used as an easy-to-handle platform to induce fluorescence anisotropy in photonic materials.

Probing plasma-treated graphene using hyperspectral Raman

Raman spectroscopy provides rich optical signals that can be used, after data analysis, to assess if a graphene layer is pristine, doped, damaged, functionalized, or stressed. The area being probed by a conventional Raman spectrometer is, however, limited to the size of the laser beam (∼1 µm); hence, detailed mapping of inhomogeneities in a graphene sample requires slow and sequential acquisition of a Raman spectrum at each pixel. Studies of physical and chemical processes on polycrystalline and heterogeneous graphene films require more advanced hyperspectral Raman capable of fast imaging at a high spatial resolution over hundreds of microns. Here, we compare the capacity of two different Raman imaging schemes (scanning and global) to probe graphene films modified by a low-pressure plasma treatment and present an analysis method providing assessments of the surface properties at local defects, grain boundaries, and other heterogeneities. By comparing statistically initial and plasma-treated regions of graphene, we highlight the presence of inhomogeneities after plasma treatment linked to the initial state of the graphene surface. These results provided statistical results on the correlation between the graphene initial state and the corresponding graphene-plasma interaction. This work further demonstrates the potential use of global hyperspectral Raman imaging with advanced Raman spectra analysis to study graphene physics and chemistry on a scale of hundreds of microns.

Type A competitiveness traits correlate with downregulation of c-Fos expression in patients with type 1 diabetes

AIM

Type A personality has been associated with increased survival in people with type 1 diabetes (T1D). Systemic low-grade inflammation may play a critical role, as suggested in recent reports, although the links between the inflammatory circulating transcriptome and Type A remain unknown. This prompted our exploration of the potential associations between Type A personality and c-Fos gene expression, a candidate gene closely linked to inflammatory processes, in T1D.

METHODS

Type A personality was assessed by Bortner questionnaire in patients with T1D, and two subscales - 'speed' and 'competitiveness' - were used to measure these specific dimensions of Type A. Expression of the c-Fos gene was assessed by a quantitative real-time polymerase chain reaction technique.

RESULTS

This pilot study included 20 men with T1D. Multivariable analyses showed an independent inverse association between Type A competitiveness score and c-Fos expression, while a regression model adjusted for age, body mass index and HbA_1c levels revealed a significant inverse relationship between c-Fos transcripts and Type A competitiveness (P = 0.003).

CONCLUSION

This strong association between Type A competitiveness and reduced c-Fos expression is in line with recent data suggesting a psychobiological influence of the Type A profile in T1D via inflammatory pathways.

Vaginal microbiome in early pregnancy and subsequent risk of spontaneous preterm birth: a case-control study

OBJECTIVES

To explore differences in the vaginal microbiome between preterm and term deliveries.

DESIGN

Nested case-control study in 3D cohort (design, develop, discover).

SETTING

Quebec, Canada.

SAMPLE

Ninety-four women with spontaneous preterm birth as cases [17 early (<34 weeks) and 77 late (34-36 weeks) preterm birth] and 356 women as controls with term delivery (≥37 weeks).

METHODS

To assess the vaginal microbiome by sequencing the V4 region of the 16S ribosomal RNA (rRNA) gene in swabs self-collected during early pregnancy.

MAIN OUTCOME MEASURES

Comparison of relative abundance of bacterial operational taxonomic units and oligotypes and identifying vaginal community state types (CSTs) in early or late spontaneous preterm and term deliveries.

RESULTS

Lactobacillus gasseri/ Lactobacillus johnsonii (coefficient -5.36, 95% CI -8.07 to -2.65), Lactobacillus crispatus (99%)/ Lactobacillus acidophilus (99%) (-4.58, 95% CI -6.20 to -2.96), Lactobacillus iners (99%)/ Ralstonia solanacearum (99%) (-3.98, 95% CI -6.48 to -1.47) and Bifidobacterium longum/ Bifidobacterium breve (-8.84, 95% CI -12.96 to -4.73) were associated with decreased risk of early but not late preterm birth. Six vaginal CSTs were identified: four dominated by Lactobacillus; one with presence of bacterial vaginosis-associated bacteria (Gardnerella vaginalis, Atopobium vaginae and Veillonellaceae bacterium) (CST IV); and one with nondominance of Lactobacillus (CST VI). CST IV was associated with increased risk of early (4.22, 95% CI 1.24-24.85) but not late (1.63, 95% CI 0.68-5.04) preterm birth, compared with CST VI.

CONCLUSIONS

Lactobacillus gasseri/L. johnsonii, L. crispatus/L. acidophilus, L. iners/R. solanacearum and B. longum/B. breve may be associated with decreased risk of early preterm birth. A bacterial vaginosis-related vaginal CST versus a CST nondominated by Lactobacillus may be associated with increased risk of early preterm birth.

TWEETABLE ABSTRACT

Largest study of its kind finds certain species of vaginal Lactobacillus + Bifidobacterium may relate to lower risk of preterm birth.

Maternal and fetal genetic contribution to gestational weight gain

BACKGROUND

Clinical recommendations to limit gestational weight gain (GWG) imply high GWG is causally related to adverse outcomes in mother or offspring, but GWG is the sum of several inter-related complex phenotypes (maternal fat deposition and vascular expansion, placenta, amniotic fluid and fetal growth). Understanding the genetic contribution to GWG could help clarify the potential effect of its different components on maternal and offspring health. Here we explore the genetic contribution to total, early and late GWG.

PARTICIPANTS AND METHODS

A genome-wide association study was used to identify maternal and fetal variants contributing to GWG in up to 10 543 mothers and 16 317 offspring of European origin, with replication in 10 660 mothers and 7561 offspring. Additional analyses determined the proportion of variability in GWG from maternal and fetal common genetic variants and the overlap of established genome-wide significant variants for phenotypes relevant to GWG (for example, maternal body mass index (BMI) and glucose, birth weight).

RESULTS

Approximately 20% of the variability in GWG was tagged by common maternal genetic variants, and the fetal genome made a surprisingly minor contribution to explain variation in GWG. Variants near the pregnancy-specific beta-1 glycoprotein 5 (PSG5) gene reached genome-wide significance (P=1.71 × 10-8) for total GWG in the offspring genome, but did not replicate. Some established variants associated with increased BMI, fasting glucose and type 2 diabetes were associated with lower early, and higher later GWG. Maternal variants related to higher systolic blood pressure were related to lower late GWG. Established maternal and fetal birth weight variants were largely unrelated to GWG.

CONCLUSIONS

We found a modest contribution of maternal common variants to GWG and some overlap of maternal BMI, glucose and type 2 diabetes variants with GWG. These findings suggest that associations between GWG and later offspring/maternal outcomes may be due to the relationship of maternal BMI and diabetes with GWG.

Mendelian randomization supports causality between maternal hyperglycemia and epigenetic regulation of leptin gene in newborns

Leptin is an adipokine that acts in the central nervous system and regulates energy balance. Animal models and human observational studies have suggested that leptin surge in the perinatal period has a critical role in programming long-term risk of obesity. In utero exposure to maternal hyperglycemia has been associated with increased risk of obesity later in life. Epigenetic mechanisms are suspected to be involved in fetal programming of long term metabolic diseases. We investigated whether DNA methylation levels near LEP locus mediate the relation between maternal glycemia and neonatal leptin levels using the 2-step epigenetic Mendelian randomization approach. We used data and samples from up to 485 mother-child dyads from Gen3G, a large prospective population-based cohort. First, we built a genetic risk score to capture maternal glycemia based on 10 known glycemic genetic variants (GRS10) and showed it was an adequate instrumental variable (β = 0.046 mmol/L of maternal fasting glucose per additional risk allele; SE = 0.007; P = 7.8 × 10(-11); N = 467). A higher GRS10 was associated with lower methylation levels at cg12083122 located near LEP (β = -0.072 unit per additional risk allele; SE = 0.04; P = 0.05; N = 166). Direction and effect size of association between the instrumental variable GRS10 and methylation at cg12083122 were consistent with the negative association we observed using measured maternal glycemia. Lower DNA methylation levels at cg12083122 were associated with higher cord blood leptin levels (β = -0.17 log of cord blood leptin per unit; SE = 0.07; P = 0.01; N = 170). Our study supports that maternal glycemia is part of causal pathways influencing offspring leptin epigenetic regulation.

Management of renal collecting duct carcinoma: a systematic review and the McMaster experience

INTRODUCTION

Collecting duct carcinoma (cdc) is a rare, aggressive form of renal carcinoma that presents at an advanced stage and has a poor prognosis. Little is known concerning the optimal management of cdc. We present the results of a systematic review addressing the management of cdc and the McMaster University cdc series.

METHODS

The medline, Cochrane Library, and embase databases and conference proceedings were searched to identify studies relating to the management of cdc. Included studies reported on a minimum of 10 subjects receiving a single intervention. Series in which an evaluation of therapeutic effectiveness was not possible were excluded. The McMaster University (Hamilton, Ontario) series of 6 cases of cdc were retrospectively reviewed.

RESULTS

We identified 3 studies relevant to the management of cdc that included a total of 72 patients. A gemcitabine-cisplatin or -carboplatin regimen resulted in a 26% objective response rate in 23 patients with metastatic cdc. Two additional studies indicated that 49 patients treated with immunotherapy achieved no response. In the McMaster series, cytoreductive nephrectomy was performed in 4 of 6 patients. In 2 patients, mvac therapy (methotrexate-vinblastine-doxorubicin-cisplatin) achieved no response. No significant therapeutic complications occurred, but survival was poor (median: 11 months; range: 10-33 months).

CONCLUSIONS

Our review and clinical experience suggest that the current standard of care for metastatic cdc is a gemcitabine-cisplatin regimen.

SIRT1 regulates dendritic development in hippocampal neurons

Dendritic arborization is required for proper neuronal connectivity. SIRT1, a NAD+ dependent histone deacetylase, has been associated to ageing and longevity, which in neurons is linked to neuronal differentiation and neuroprotection. In the present study, the role of SIRT1 in dendritic development was evaluated in cultured hippocampal neurons which were transfected at 3 days in vitro with a construct coding for SIRT1 or for the dominant negative SIRT1H363Y, which lacks the catalytic activity. Neurons overexpressing SIRT1 showed an increased dendritic arborization, while neurons overexpressing SIRT1H363Y showed a reduction in dendritic arbor complexity. The effect of SIRT1 was mimicked by treatment with resveratrol, a well known activator of SIRT1, which has no effect in neurons overexpressing SIRT1H363Y indicating that the effect of resveratrol was specifically mediated by SIRT1. Moreover, hippocampal neurons overexpressing SIRT1 were resistant to dendritic dystrophy induced by Aβ aggregates, an effect that was dependent on the deacetylase activity of SIRT1. Our findings indicate that SIRT1 plays a role in the development and maintenance of dendritic branching in hippocampal neurons, and suggest that these effects are mediated by the ROCK signaling pathway.

A granular variant of CD63 is a regulator of repeated human mast cell degranulation

BACKGROUND

Mast cells are secretory immune cells whose degranulation can provoke acute allergic reactions. It is presently unclear, however, whether an individual mast cell can repeatedly degranulate or turns dysfunctional after a single antigen stimulus. This work thus aims to better define the mast cell life cycle, with particular focus on new target structures for therapeutic or diagnostic approaches in allergy.

METHODS

Monoclonal antibodies were raised against degranulated cord blood-derived human mast cells. A subset of these antibodies that exclusively recognized degranulated mast cells, but did not cross-react with quiescent mast cells or other hematopoietic cell types, became key reagents in subsequent experiments.

RESULTS

We identified a granular variant of tetraspanin CD63 as an exclusive molecular marker of degranulated human mast cells. Mutant analyses indicate that a cysteine cluster around residue C170 and protein glycosylation at residue N172 account for the antibody specificity. Here, we show that mast cells, which underwent an initial FcεRI-mediated degranulation, can be degranulated for at least another cycle in vitro. Repeated degranulation, however, requires an IgE/antigen stimulus that differs from the preceding one. Furthermore, the new variant-specific anti-CD63 antibodies effectively impair repeated cycles of mast cell degranulation.

CONCLUSION

Our findings indicate that mast cells are stable, multiple-use cells, which are capable of surviving and delivering several consecutive hits. Surface expression of the novel CD63 variant is a distinguishing feature of such primed cells. Reagents directed against this molecular hallmark may thus become valuable diagnostic and therapeutic agents.

Secular changes in incidence and mortality associated with Staphylococcus aureus bacteraemia in Quebec, Canada, 1991-2005

In order to examine secular changes in the incidence and mortality associated with Staphylococcus aureus bacteraemia before and after the emergence of methicillin-resistant S. aureus (MRSA), a retrospective cohort study of 815 patients with S. aureus bacteraemia was performed in the Estrie region of Quebec, Canada, between 1991 and 2005. The primary outcome was all-cause 30-day mortality. Between 1991-1993 and 2003-2005, the proportion of cases attributed to endocarditis and pneumonia increased from 4% to 11% and from 2% to 11%, respectively, while that attributed to catheter infections decreased from 49% to 17%. MRSA was almost absent in 1991-1999, but accounted for 10% and 20% of cases in 2000-2002 and 2003-2005, respectively. The population incidence of bacteraemia caused by methicillin-susceptible S. aureus (MSSA) remained stable between 1997 and 2005, while that of MRSA increased from 0 to 7.4/100 000. Risk-factors for mortality included age, co-morbidities, female gender, residence outside the city of Sherbrooke, pneumonia (OR 3.35, 95% CI 1.96-5.73) or endocarditis (OR 2.89, 95% CI 1.67-5.01) as the source, and an absence of treatment. After adjusting for confounders, patients with MRSA bacteraemia had a higher mortality rate than those with MSSA bacteraemia (OR 2.21, 95% CI 0.99-4.96, p 0.053). Mortality in patients with MSSA bacteraemia was 19% (16/83) in 1991-1993, 23% (26/113) in 1994-1996, 29% (50/173) in 1997-1999, and 28% (52/185) in 2000-2002, decreasing to 15% (28/192) in 2003-2005, which impacted on the relative mortality rates of MRSA and MSSA. MRSA did not replace, but added to, an existing stable incidence of MSSA bacteraemia.

Production, formulation and antagonistic activity of the biocontrol like-yeast Aureobasidium pullulans against Penicillium expansum

Aureobasidium pullulans (de Bary) Arnaud (Ach 1-1) was grown in a glucose fed-batch fermentor to 106 g dry wt l(-1) in 48 h. The cells were dried in a fluidized bed dryer with a final viability of 62%. After 7 months at 4 degrees C, the viability was 28% of the initial value (= 2.3 x 10(10 )c.f.u. g(-1) dry matter). A protection level of 89% was achieved with the biomass preparation at 1 x 10(8 )c.f.u. ml(-1) after 28 and 7 days for apples stored respectively at 5 and 25 degrees C against Penicillium expansum. Our process is suitable to produce large quantities of the strain Ach 1-1 as biological control agent for apple preservation.

Pharmacokinetics of mycophenolic acid in kidney transplant patients receiving sirolimus versus cyclosporine

INTRODUCTION

Mycophenolic acid (MPA) pharmacokinetics exhibit large variability in transplant recipients and may be altered due to concurrent immunosuppressants. Little is known about the influence of sirolimus (SRL) on MPA pharmacokinetics in kidney transplant patients.

METHODS

We studied the areas under concentration-time curves (AUC) for MPA in 15 patients receiving immunosuppression combining SRL with mycophenolate mofetil (MMF). The pharmacokinetic measurements were performed in all patients using three MMF dosing regimens (0.5 g twice a day, 0.75 g twice a day, 1 g twice a day). Similar blood AUC profiles were also sampled from 12 patients treated with a fixed dose of MMF 1 g twice a day and cyclosporine (CsA). MPA was measured using HPLC; the AUC0-12 of MPA was determined by the trapezoidal method using four sampling time points: C0, C1, C3, C5.

RESULTS

While patients on SRL were receiving 0.75 g MMF twice a day, mean AUC0-12 and C0 values of MPA were comparable to those of patients receiving CsA and 1 g MMF twice a day (54.1 +/- 17.6 and 3 +/- 1.87 vs 51.7 +/- 16.7 mg.h/L and 2.76 +/- 1.57 mg/L, respectively). On the other hand, 0.5 g MMF twice a day with SRL therapy resulted in AUC0-12 and C0 values of MPA of 32.3 +/- 12.6 mg.h/L and 2.32 +/- 1.72 mg/L, respectively, whereas, 1 g MMF twice a day with SRL resulted in AUC0-12 and C0 values of MPA of 70.9 +/- 19.3 mg.h/L and 4.7 +/- 2.44 mg/L, respectively.

CONCLUSIONS

These findings demonstrate that MPA exposure in the presence of SRL is higher than that with CsA. It appears that the MMF dose should be reduced to 0.75 g twice a day in patients receiving SRL to obtain AUC0-12 of MPA levels comparable to that in patients treated with CsA and MMF 1 g twice a day.

Myricetin, quercetin and catechin-gallate inhibit glucose uptake in isolated rat adipocytes

The facilitative glucose transporter, GLUT4, mediates insulin-stimulated glucose uptake in adipocytes and muscles, and the participation of GLUT4 in the pathogenesis of various clinical conditions associated with obesity, visceral fat accumulation and insulin resistance has been proposed. Glucose uptake by some members of the GLUT family, mainly GLUT1, is inhibited by flavonoids, the natural polyphenols present in fruits, vegetables and wine. Therefore it is of interest to establish if these polyphenolic compounds present in the diet, known to be effective antioxidants but also endowed with several other biological activities such as protein-tyrosine kinase inhibition, interfere with GLUT4 function. In the present study, we show that three flavonoids, quercetin, myricetin and catechin-gallate, inhibit the uptake of methylglucose by adipocytes over the concentration range of 10-100 microM. These three flavonoids show a competitive pattern of inhibition, with K(i)=16, 33.5 and 90 microM respectively. In contrast, neither catechin nor gallic acid inhibit methylglucose uptake. To obtain a better understanding of the interaction among GLUT4 and flavonoids, we have derived a GLUT4 three-dimensional molecular comparative model, using structural co-ordinates from a GLUT3 comparative model and a mechanosensitive ion channel [PDB (Protein Data Bank) code 1MSL] solved by X-ray diffraction. On the whole, the experimental evidence and computer simulation data favour a transport inhibition mechanism in which flavonoids and GLUT4 interact directly, rather than by a mechanism related to protein-tyrosine kinase and insulin signalling inhibition. Furthermore, the results suggest that GLUT transporters are involved in flavonoid incorporation into cells.

[Binucleated lymphocyte lymphocytosis]

We reported here a case of persistent polyclonal B-cell lymphocytosis (PPBL) in a 31-year-old female patient. Peripheral blood smears showed atypical binucleated lymphocytes which were polyclonal B-cells with kappa and lambda expression, and without clonal rearrangement of immunoglobulin heavy chain. Cytogenetic analysis found a trisomy 8, with premature chromosome condensation. Clinically, PPBL is associated with moderated splenomegaly, adenopathy, and smoking. It remains to be established whether PPBL is a real pathology or a simple cytological abnormality.

Molecular and biochemical characterization of endo-beta-mannanases from germinating coffee (Coffea arabica) grains

The activity of endo-beta-mannanase ([1-->4]-beta-mannan endohydrolase EC 3.2.1.78) is likely to be central to the metabolism of cell wall mannans during the germination of grains of coffee (Coffea spp.). In the present paper, we report the cloning and sequencing of two endo-beta-mannanase cDNAs (manA and manB) by different strategies from Coffea arabica L.. The manA cDNA was obtained by the use of oligonucleotides homologous to published sequences of other endo-beta-mannanases and manB by the use of oligonucleotides deduced from a purified enzyme from coffee. ManA and B proteins share about 56% sequence homology and include highly conserved regions found in other mannan endohydrolases. Purification of the activity by chromatography followed by separation by two-dimensional electrophoresis and amino acid sequencing demonstrated the existence of at least seven isomers of the ManB form. The existence of multiple manB genes was also indicated by Southern analysis, whereas only one or two gene copies were detected for manA. Northern hybridizations with manA- and manB-specific probes showed that mRNA transcripts for both cDNAs were present at the same periods of bean germination with transcript peaks at 20 days after imbibition of water (DAI). Transcripts were not detected during grain maturation or in the other tissues such as roots, stems, flowers and leaves. The peak endo-beta-mannanase activity occurred at approximately 28 DAI and was not detected in grains prior to imbibition. Activity and mRNA levels appeared to be tightly co-ordinated. Tests of substrate specificity with the purified ManB enzyme showed that activity required a minimum of five mannose units to function efficiently.

Disease knowledge in a high-risk population for cystic fibrosis

Cystic fibrosis (CF) has high incidence (1/936 live births) and carrier rate (1/15 inhabitants) in Saguenay-Lac-Saint-Jean (SLSJ). One objective of a major enquiry among several subsets of individuals from this high-risk population for CF was to evaluate the knowledge of the disease and its genetic transmission. The overall score of correct answers pertaining to the clinical signs of CF among medical doctors (general practitioners and specialists) was 42.2 and 65.6%, respectively; it was 84.2% for questions regarding the genetic transmission of CF. The knowledge of the clinical signs was reasonable among CF patients and their parents (about 65% of correct answers), but it was much higher for the genetics (over 88% among parents). Aunts and uncles of CF children were poorly informed of the clinical signs (33.9% of correct answers) but well informed of the genetic transmission (73.8%). Specific subsets of the SLSJ population showed important gaps in the knowledge of the clinical signs of CF but, overall, they were well informed of its genetic transmission.

Isoelectric focusing of red cell phosphoglucomutase (E.C.: 2.7.5.1) at the PGM1 locus in a French-Canadian population

Phosphoglucomutase1 (PGM1) polymorphism was studied in a French-Canadian population of Québec city, Canada by means of a low voltage (max 500 V) isoelectric focusing (IEF) procedure on vertical polyacrylamide gel slabs. Frequencies of the four common PGM1 genes estimated from the phenotype distribution in 308 unrelated individuals were PGM1(1+), 0.61 (+/- 0.02); PGM1(1-), 0.13 (+/- 0.01); PGM1(2+), 0.18 (+/- 0.02); and PGM1(2-), 0.08 (+/- 0.01). The segregation patterns observed in 154 families, which included 31 different mating types and 353 children, confirmed a Mendelian inheritance of four autosomal genes. The distribution of the PGM1 phenotypes observed or expected in a Hardy-Weinberg equilibrium was compared with that of other populations. A significant (P < 0.001) difference was found between the Québec population and a Black population from Keneba, Gambia, West-Africa.