Mobility and transformation of CdSe/ZnS quantum dots in soil: Role of the capping ligands and ageing effect.

The increasing application of Quantum Dots (QDs) is cause of concern for the potential negative effects for the ecosystem, especially in soils that may act as a sink. In this study, soil leaching experiments were performed in quartz sand packed columns to investigate the behavior of core-shell CdSe/ZnS QDs coated with either small ligands (TGA-QDs) or more complex polymers (POAMA-QDs). Fluorescence emission was compared to mass spectrometric measurements to assess the nanoparticles (NPs) state in both the leachate (transported species) and porous media (deposited amounts). Although both QDs were strongly retained in the column, large differences were observed depending on their capping ligand stability. Specifically, for TGA-QDs elution was negligible and the retained fraction accumulated in the top-columns. Furthermore, 74% of the NPs were degraded and 38% of the Se was found in the leachate in non-NPs state. Conversely, POAMA-QDs were recovered to a larger extent (78.1%), and displayed a higher transport along the soil profile. Further experiments with altered NPs showed that homo-aggregation of the QDs prior injection determined a reduced mobility but no significant changes in their stability. Eventually, ageing of the NPs in the column (15 days) caused the disruption of up to 92% of the original QDs and the immobilization of NPs and metals. These results indicate that QDs will accumulate in top-soils, where transformations phenomena will determine the overall transport, persistency and degradation of these chemicals. Once accumulated, they may act as a source for potentially toxic Cd and Se metal species displaying enhanced mobility.

Selective and High Dynamic Range Assay Format for Multiplex Detection of Pathogenic Pseudomonas aeruginosa, Salmonella typhimurium, and Legionella pneumophila RNAs Using Surface Plasmon Resonance Imaging.

Due to its well-characterized and highly conserved structure, as well as its relative abundance in metabolically active cells, bacterial 16S rRNA sequence plays an important role in microbial identification. In this work, a biosensing strategy has been developed for simultaneous detection of 16S rRNA analytes of three pathogenic bacterial strains: Legionella pneumophila, Pseudomonas aeruginosa, and Salmonella typhimurium. Surface plasmon resonance imaging (SPRi) was used as a detection technique coupled with DNA probe sandwich assemblies and gold nanoparticles (GNPs) for signal amplification. The targets 16S rRNA were selectively captured at the interface of the biosensor by surface-bound DNA probes through a hybridization process. GNP-grafted DNA detection probes were then introduced and were hybridized with a defined 16S rRNA region on the long DNA-RNA sandwich assemblies, resulting in a significant increase of the SPR signal. The results demonstrated the successful implementation of this strategy for detecting 16S rRNA sequences in total RNA mixed samples extracted from the three pathogenic strains at a concentration down to 10 pg mL-1 with a large dynamic range of 0.01-100 ng mL-1 and high selectivity. Since no particular optimization of the probe design was applied, this method should be relatively easy to adapt for quantification of a wide range of bacteria in various liquids.

Affordable CD4 T-cell enumeration for resource-limited regions: a status report for 2008.

BACKGROUND: The global struggle with human immunodeficiency virus (HIV) and the battle to develop affordable CD4 T-cell counting technology are both unfulfilled goals in 2008. The need for such instrumentation is more critical now as implementation of antiretroviral therapy (ART) is in progress in many resource limited regions. Major scaling-up efforts in rural situations are difficult to implement without laboratory infrastructure. CD4 T-cell counting is especially critical when trying to reach individuals with HIV to have them enrolled in ART as soon as they qualify for treatment based on CD4 count. METHOD: This review covers both the chronological evolution and the scientific milestones of technological development of affordable immunophenotyping. It is more focused on flow cytometry but does consider the potential contribution by digital image cytometry. RESULTS: Thus far flow cytometry offered only modest progress toward affordable immunophenotyping. A list with desirable features is offered for side by side comparison. Digital image cytometry has yet to show its enormous affordable market potential. CONCLUSIONS: It is possible to develop truly affordable, portable flow cytometry but it is not here yet. There are some hopeful signs as there are innovative and practical technical components appearing at regular intervals. However, so far the technical breakthroughs have been fragmented efforts without any attempts to consider intercorporate collaboration to optimize critical mass and synergy. The smaller players in the industry have made some progress toward meeting the monumental needs in Africa and Asia. Digital image cytometry may well be the ultimate winner in the affordable technology race.

Family history of anxiety and mood disorders in anorexia nervosa: review of the literature.

OBJECTIVE: To provide a critical review of the research on mood and anxiety disorders in relatives of individuals with anorexia nervosa (AN). In the first section, we explore methodological issues with these studies. In the second section, we present results. METHOD: A Medline search identified studies published on family history of mood and anxiety disorders in AN, and was complemented by a manual search. Only studies from 1980 to 2006 using strict diagnostic criteria for the disorders were included [Feighner and Halmi criteria for AN, Reasearch Diagnostic Criteria (RDC), Diagnostic and Statistical Manual of Mental Disorders - Third Edition - Revised (DSM-III-R) or DSM - Fourth Edition (DSM-IV) for anorexia and other disorders]. RESULTS: A review of the research methods used in the studies revealed a number of methodological problems. Therefore, we provide only a description of the prevalence of mood and anxiety disorders in relatives of individuals with AN. CONCLUSIONS: In the light of the methodological issues uncovered, the value of the results of these studies and their implications for further study are considered.

[Mood and anxiety disorders in relatives of anorexia nervosa patients: a review]. / Antécédents familiaux de troubles anxieux et de troubles de l'humeur dans l'anorexie mentale.

UNLABELLED: In the literature, no review concerning the family comorbidity of mood and anxiety disorders of anorexic subjects exists. However, this data can be important for the comprehension of this disorder and for the assumption of responsibility. OBJECTIVE: We conducted a critical literature review on studies assessing the prevalence of anxiety disorders (AD) and mood disorders in relatives of anorexia nervosa (AN) subjects. In the first part, we discuss methodological issues relevant to these comorbidity studies. In the second part, taking into account the methodological considerations raised, we summarise the findings of these studies. METHOD: We performed a manual and computerised search (Medline) for all published studies on the frequency of MD and AD in AN relatives and MD or AD, limiting our search to the 1980-2002 period, in order to get sufficiently homogeneous diagnostic criteria for both categories of disorders (most often RDC, DSM III, DSM III-R, or DSM IV criteria). RESULTS: We review methodological issues regarding population sources, general methodological procedures, diagnostic criteria for AN, MD and AD, diagnostic instruments, age of subjects and course of the eating disorder. DISCUSSION: We discuss the results taking into account the methodological problems observed. We give implications for reviewing the results of published studies and planning future research.

[On the subject of the cyclic vomiting syndrome]. / A propos du syndrome des vomissements cycliques.

The cyclic vomiting syndrome is defined by episodes of vomiting lasting from hours to days with free intervals between episodes. Various symptoms can be associated with vomiting: nausea, abdominal pain, photophobia, fever, pallor, dehydratation, excess salivation, social withdrawal. Some factors often precipitate the crisis: infection, psychological stresses, menstruation. Excluding a medical condition, especially a gastro-intestinal or a neurological disease is compulsory for the diagnostic of cyclic vomiting syndrome. The cyclic vomiting syndrome shares many common features with migraine including treatment. Due to negative paraclinical testing, a psychiatric disease is often suspected in these children. Pathophysiology of cyclic vomiting syndrome is unknown. As for migraine, mitochondrial and ionic channels abnormalities are thought to play a role. Overactivation of hypothalamic-pituitary-adrenal axis and autonomic dysfunction seem to be involved too. Three clinical vignets will illustrate these aspects.

Impact of unified procedures as implemented in the Canadian Quality Assurance Program for T lymphocyte subset enumeration. Participating Flow Cytometry Laboratories of the Canadian Clinical Trials Network for HIV/AIDS Therapies.

The objective of the Canadian Quality Assurance Program (CQAP) is to provide the most reproducible and accurate T-cell subset enumeration for individuals living with HIV who are enrolled in the Canadian Clinical Trial Network for Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) Therapies (abbreviated as CTN). The Canadian National Laboratory for Analytical Cytology, within the Laboratory Centre for Disease Control, is part of the Health Protection Branch of Health Canada. For the past eight years, the Laboratory for Analytical Cytology has been responsible for delivering a bilingual quality assurance program for CD4 T-cell enumeration. This federal program, which integrates biotechnology transfer with quality assessment, was achieved through the organization of workshops focused on technology transfer and essential skill-building techniques. Two training sessions were conducted for the CTN flow cytometer operators. The first introduced the concept of window of analysis, to demonstrate the practical benefits of unified quantitative fluorescent measurement. As a follow-up to the first workshop, participants performed a series of quantitative assays that monitored the expression of CD69, an early activation marker. This quantitative fluorescence protocol was performed with acceptable inter-laboratory variation using modified commercial kits. The second workshop focused on a absolute count method based on a single platform. Four preserved whole-blood preparations were tested with this approach. The combined effort reduced inter-laboratory variation. The direct impact was monitored as related to the frequency of participation. Over the years, the standard deviation of average accumulated variation decreased dramatically with increased frequency of participation, from 10% to <4%.

Monoclonal idiotypic and anti-idiotypic antibodies to human immunodeficiency virus type 1 envelope glycoprotein.

Murine monoclonal antibodies (MAbs) gp41-1 (IgG2a) and gp41-2 (IgG1), directed against the envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1), were produced and characterized. These MAbs recognized both gp160 and gp41 and reacted with divergent HIV-1 isolates. Surface binding assays using viable HIV-infected cells indicated that these MAbs were directed against surface-exposed epitopes. Both MAbs caused a reduction in reverse transcriptase activity. Syngeneic monoclonal antiidiotypic antibodies (anti-ids) against gp41-1 were also generated. Six anti-ids (agp41-11 to agp41-16) were selected by ELISA using F(ab')2 fragments of gp41-1; no reaction was observed when fragments from an irrelevant IgG2a MAb were used. Anti-ids were recognized by both gp41-1 and gp41-2 biotinylated MAbs. Competitive ELISA studies suggested that anti-ids were directed against at least three distinct idiotopes on gp41-1. All anti-ids reacted with idiotopes associated with both heavy and light chains and not with separated chains. The binding of MAbs gp41-1 and gp41-2 to HIV-infected cells was inhibited by each anti-id, except for the binding of gp41-2 which was not affected by the presence of agp41-12. Immunization of rabbits with agp41-11 and agp41-13 resulted in an antibody response against recombinant gp160. These studies indicated that these two anti-ids contain a surrogate image of the antigen recognized by gp41-1.

Properties of three monoclonal antibodies that recognize an 80-kDa phytohemagglutinin-binding glycoprotein from porcine lymphocytes.

Monoclonal antibodies (mAbs) directed against porcine splenocyte phytohemagglutinin receptor glycoproteins were produced in BALB/c mice. Three antibody-producing, stable hybridomas were cloned and expanded in the peritoneal cavity of BALB/c mice. The mAbs (A7, B1, and H3) were purified and belong to the IgG2 subclass of immunoglobulins (kappa light chain). Each 125I-labeled mAb bound to purified porcine splenocytes with an (apparent) affinity KA congruent to 10(8) M-1 (Scatchard analysis). The number of (apparent) binding sites was 5 x 10(4) sites/cell in the case of B1 and H3, and approximately 15 x 10(4) sites/cell for A7. Immunoprecipitation experiments showed that the three mAbs recognized a single antigenic protein of Mr 80 kilodaltons (gp80). In addition, each mAb recognized a different epitope of gp80, as observed by Western blot analyses. Assessment of the relative ability of anti-gp80 mAbs to stimulate porcine splenocytes as determined by [3H]thymidine incorporation showed weak (A7 and B1) or no (H3) mitogenic activity. Cross-linked anti-gp80 mAbs were not mitogenic, except in the case of B1. In contrast, each anti-gp80 mAb (cross-linked or untreated) showed synergistic mitogenic properties when used in combination with a suboptimal concentration of phytohemagglutinin. The mechanism involved in this synergistic effect is discussed.

Compact, low-loss, fused biconical taper couplers: overcoupled operation and antisymmetric supermode cutoff.

The automated manufacture and characterization of compact four-port highly overcoupled fused couplers is reported. During the pulling stage of the manufacturing process, the light power in such devices is observed to cycle back and forth up to 1000 times between the two output ports for elongations smaller than 20 mm. For sufficiently long pulls, antisymmetric supermode cutoff has been observed for the first time to our knowledge, manifested by a sudden cessation of the coupling process. The measured wavelength dependence of the coupling ratio together with the device dimensions are consistent with the observation of cutoff as observed in pull-signature characteristics.