Inhibitory and neutral antibodies to Plasmodium falciparum MSP119 form ring structures with their antigen

Blood-stage malaria vaccine candidates include surface proteins of the merozoite. Antibodies to these proteins may either block essential steps during invasion or render the merozoite susceptible to phagocytosis or complement-mediated degradation. Structural information on merozoite surface proteins complexed to antibodies provides crucial information for knowledge-based vaccine design. The major merozoite surface protein MSP1 is an abundant surface molecule in Plasmodium falciparum. Only a subset of antibodies against MSP119 inhibits invasion (inhibitory antibodies), whereas other antibodies binding to MSP119 have no effect on invasion (neutral antibodies). Here we report on the complex of MSP119 with both inhibitory monoclonal antibody 12.10 and neutral monoclonal antibody 2F10. The complexes were established using both whole IgG's and Fab fragments, and analysed by dynamic light scattering, electron microscopy and analytical ultra centrifugation. Specific ring structures were formed in the ternary complex with the two antibodies, providing direct evidence of non-overlapping epitopes on MSP119. Mutational studies also indicated that the epitopes of the inhibitory and neutral antibodies are spatially remote.     

Bileaflet Aortic Valve Prosthesis Pivot Geometry Influences Platelet Secretion and Anionic Phospholipid Exposure

The clinical histories of the Medtronic Parallel (MP) and St. Jude Medical (SJM) Standard valves suggest pivot geometry influences the thrombogenic characteristics of bileaflet prostheses. This work studied the effects of various pivot geometries on markers of platelet damage in a controlled, in vitro apparatus. The Medtronic Parallel valve, two St. Jude Medical valves, and two demonstration prostheses were used to study the effects of bileaflet pivot design, gap width, and size on platelet secretion and anionic phospholipid expression during leakage flow. A centrifugal pump was used to drive blood through a circuit containing a bileaflet prosthesis. Samples were taken at set time intervals after the start of the pump. These samples were analyzed by cell counting, flow cytometry, and enzyme-linked immunosorbant assay. No significant differences were observed in platelet secretion or anionic phospholipid expression between experiments with the SJM 27 Standard regular leaker, the SJM 20 regular leaker, and the MP 27 valves. Significant differences in platelet secretion and anionic phospholipid expression were observed between a SJM 27 Standard regular leaker and a SJM 27 high leaker valve. These studies suggest that leakage gap width within bileaflet valve pivots has a significant effect on platelet damage initiated by leakage flow. © 2001 Biomedical Engineering Society. PAC01: 8719Uv, 8719Tt, 8380Lz, 8768+z     

Reliability and Construct Validity of the Malay Version of Theory of Planned Behaviour (TPB) for Smoking Cessation

Objective: The aim of this study was to evaluate the psychometric properties of the Malay translated version ofthe Theory of Planned Behavior (TPB) intention to quit smoking questionnaire. Methods: A cross-sectional studywas performed involving 185 male smokers. The forward-backward translation procedure was adopted to translate thequestionnaire from English to Malay. The internal consistency and stability were assessed using Cronbach’s alpha and acorrelation analysis and Exploratory Factor Analysis was conducted. Result: The translated questionnaire showed goodinternal consistency with Cronbach’s alpha values of 0.86, 0.64, 0.74 and 0.90 for each of the four respective factors.The test-retest reliability revealed acceptable stability, with Spearman’s correlation coefficients ranging from low tomoderate (r>0.30-0.50) and a satisfactory inter class correlation coefficient (ICCs). The construct validity achieved anacceptable factor loading for each construct which ranged from 0.40 to 0.90. Conclusion: The current study providedpsychometric evidence for an appropriate, reliable and valid tool of TPB Malay version. This questionnaire could beapplied in evaluating smoking cessation interventions in Malaysia.     

Application of the ISTH bleeding score in hemophilia

Background

Hemophilia is an inherited bleeding disorder. With proper treatment and self-care, persons with hemophilia can maintain an active, productive lifestyle. Hemophilia can be mild, moderate, or severe, depending on the degree of plasma clotting factor deficiency. The aim of the study was to assess the utility of ISTH-BAT in diagnosis, determining severity of the bleeding condition in newly diagnosed and known hemophilia patients, compare the bleeding score (BS) in adult and pediatric groups and investigate its association with plasma factor levels.

Trypanosoma cruzi nucleoside triphosphate diphosphohydrolase 1 (TcNTPDase-1) biochemical characterization,immunolocalization and possible role in host cell adhesion

Previous work has suggested that Trypanosoma cruzi diphosphohydrolase 1 (TcNTPDase-1) may be involved in the infection of mammalian cells and serve as a potential target for rational drug design. In this work, we produced recombinant TcNTPDase-1 and evaluated its nucleotidase activity, cellular localization and role in parasite adhesion to mammalian host cells. TcNTPDase-1 was able to utilize a broad range of triphosphate and diphosphate nucleosides. The enzyme's K_m for ATP (0.096 mM) suggested a capability to influence the host's ATP-dependent purinergic signaling. The use of specific polyclonal antibodies allowed us to confirm the presence of TcNTPDase-1 at the surface of parasites by confocal and electron microscopy. In addition, electron microscopy revealed that TcNTPDase-1 was also found in the flagellum, flagellum insertion region, kinetoplast, nucleus and intracellular vesicles. The presence of this enzyme in the flagellum insertion region and vesicles suggests that it may have a role in nutrient acquisition, and the widespread distribution of TcNTPDase-1 within the parasite suggests that it may be involved in other biological process. Adhesion assays using anti-TcNTPDase-1 polyclonal antibodies as a blocker or purified recombinant TcNTPDase-1 as a competitor revealed that the enzyme has a role in parasite–host cell adhesion. These data open new frontiers to future studies on this specific parasite–host interaction and other unknown functions of TcNTPDase-1 related to its ubiquitous localization.     

Evaluation of CINtec PLUS® testing as an adjunctive test in ASC‐US diagnosed SurePath® preparations

The CINtec PLUS® system is an immunohistochemical cocktail composed of antibodies against p16^INK4a (surrogate of HPV infection) and Ki‐67 (proliferation marker) meant to improve the sensitivity and specificity for detecting high‐grade dysplasia (HGD). In the presence of dysplasia, a red chromogen marks Ki‐67 expression in the nucleus and a brown chromogen marks cytoplasmic p16^INK4a expression. Only cells showing dual staining are interpreted as positive. This retrospective study examined the performance of CINtec PLUS testing when performed on ASC‐US diagnosed samples. Comparison was made to high‐risk HPV DNA test results and colposcopic biopsy results. Technical considerations in the interpretation of this immunohistochemical stain are additionally discussed. CINtec PLUS showed modest sensitivity (64%) and specificity (53%) in identifying the presence of HGD at surgical biopsy. Positive and negative predictive values for HGD were 28% and 83%, respectively. HR‐HPV DNA test yielded sensitivity of 100% and specificity of 21%. During interpretation, squamous metaplasia and endocervical cells were seen to show individual staining for p16^INK4a or Ki‐67. Individual staining, when present within three dimensional cellular groups common to SurePath® preparations, can be time‐intensive to interpret necessitating thoughtful examination at high power. The Pap test with HR‐HPV DNA testing is a highly sensitive test. A specific test is needed to prevent false positives and over treatment. The CINtec® system provides a modest increase in specificity beyond HR‐HPV DNA testing. Future study of its appropriateness and cost‐ffectiveness in a treatment algorithm are warranted. Diagn. Cytopathol. 2013. © 2011 Wiley Periodicals, Inc.