Enhanced cytotoxicity of rituximab following genetic and biochemical disruption of glycosylphosphatidylinositol anchored proteins

Rituximab, an anti-CD20 monoclonal antibody used to treat B cell lymphoproliferative disorders and autoimmune diseases, kills cells through complement dependent cytotoxicity, antibody-dependent cellular toxicity and apoptosis. A mechanism of resistance to rituximab is upregulation of the complement regulatory proteins, CD59 and CD55. Paroxysmal nocturnal hemoglobinuria (PNH) is a hematopoietic disorder caused by PIGA mutations that lead to a loss of all glycosylphospatidylinositol (GPI)-anchored proteins including, CD55 and CD59. We compared the cytotoxic activity of rituximab against a PNH B cell line, LD -, and the isogenic cell line LD - PIGA + in which GPI-anchor expression was restored by stable transfection of PIGA. The PNH cell line was more sensitive to rituximab-mediated killing than the LD - PIGA + cells. Biochemical disruption of GPI anchors with phosphatidylinositol specific phospholipase C (PIPLC), a phospholipase that cleaves GPI-anchored proteins, also increased rituximab-mediated killing. Thus, genetic and biochemical interruption of GPI anchor proteins augments sensitivity to rituximab.     

A new technique (the NOW test) for the detection of Streptococcus pneumoniae in the effusions of otitis media

The presence of Streptococcus pneumoniae in chronic otitis media was determined with a new antigen detection kit, the NOW test. The NOW test was originally designed as a urinary antigen test but was adapted to middle-ear effusions for the present study. Middle-ear effusions from 52 children were studied. Streptococcus pneumoniae was cultured from 10 per cent of the effusions. The NOW test was positive in 23 per cent of the effusions, 80 per cent of culture positive and 17 per cent of culture negative effusions. The NOW test proved to be rapid, simple, reliable and relatively inexpensive for the detection of pneumococcal antigen in the middle-ear effusions. This test may prove valuable for the management of children with acute otitis media who undergo tympanocentesis.     

Distributed neural activity during object,spatial and integrated processing in humans

Information about the form and the spatial location of objects is seamlessly integrated during visual perception. We used event-related potentials (ERPs) to explore neural activity related to processing form, location or the combination of both kinds of features. Healthy subjects performed three versions of a 'match-to-sample' task: a two-object task, a two-location task and an integrated object-location task. Responses were quickest and most accurate during the integrated task, slower and less accurate in the two-location task and slowest and least accurate in the two-object task. ERPs locked to the 'sample' stimulus at encoding, and to the 'target' stimulus during feature comparison differentiated between tasks. 'Sample' stimulus ERPs exhibited task-specific posterior cortical involvement in processing distinct visual features. 'Target' stimulus ERPs revealed task-related differences in features associated with frontal lobe mediated attentional processes: an early latency P300 showed increased amplitude during the integrated task. Results from this experiment support the view that distinct neural circuits mediate form vs. location processing and that form-location integration engages both pathways and upregulates frontal-parietal association networks.     

Duration of patency of laser-assisted tympanic membrane fenestration

BACKGROUND: Laser-assisted tympanic membrane fenestration (LTMF) provides intermediate-duration middle ear ventilation, which benefits selected children with acute otitis media (AOM) and otitis media with effusion (OME). OBJECTIVE: To evaluate clinical and technical factors that may affect duration of LTMF patency. DESIGN: Prospective clinical cohort effectiveness trial. SETTING: Four tertiary care children's hospitals. PATIENTS: Volunteer sample of 251 children (430 ears) followed up at 1, 2, 3, 4, 8, and 12 weeks; time to fenestration closure was evaluable in 201 ears, and assessment of cure at study conclusion was evaluable in 128 ears. INTERVENTIONS: Laser-assisted tympanic membrane fenestration for prospectively defined AOM or OME. The surgeon determined spot size, wattage, and concurrent adenoidectomy based on clinical judgment. MAIN OUTCOME MEASURES: Cure of AOM/OME with effusion at 90 days and duration of LTMF patency relative to spot size (1.8-2.8 mm), fenestration location on tympanic membrane, power (7-22 W), concurrent adenoidectomy, age, diagnosis (AOM vs OME), type of effusion, and preoperative tympanogram characteristics. Results are based on the number of ears that could be evaluated at each data collection interval. RESULTS: Fenestrations remained patent for 2 to 4 weeks (mean = 2.52, median = 2.0, SD = 1.4, n = 201); 97.4% were closed at 6-week follow-up. Spot sizes of 2.4 and 2.6 mm had a higher rate of patency than 2.0-mm spot size at 3 weeks following LTMF. Cure at 90 days was related to duration of patency for all patients combined and for patients treated for AOM and OME, but not for those undergoing adjunctive adenoidectomy. Cure at 90 days was related to larger spot size for all patients combined and those treated for AOM. Other investigated factors did not achieve statistical significance. CONCLUSIONS: Spot size of 2.4 mm or greater results in improved duration of LTMF patency, persisting for up to 3 weeks after LTMF, especially for treatment of AOM. Increased duration of LTMF patency correlates with greater incidence of cure of middle ear effusion at 90 days. Additional investigation is indicated to determine optimum spot size and optimum duration of patency for disease- severity-adjusted populations.     

Radioanalytical data interpretation when the ratio reading/median is lognormally distributed

The purpose of this paper is to assist those who might be confronted by non-normal and non-homoscedastic error distributions representable by continuous probability density functions. Methods are presented to demonstrate how mathematical algorithms can be developed to obtain a "best fit" calibration line and how uncertainty ranges in interpretations of unknowns can be obtained from the calibration. The data used to demonstrate these methods were obtained from Brookhaven National Laboratory fission track analysis data for plutonium in urine. Examination of the variability in the fission track analysis data, during the period of time that the demonstration data were collected, revealed that the deviations from the mean were neither normal nor lognormal, but the ratios of tracks divided by the median at each plutonium level were lognormally distributed. Consequently, the differences between the logarithms of observed tracks and the median were normally distributed. The new "best fit" line was obtained by minimizing a reduced chi-square statistic made up of the squared differences in logarithms, divided by the variance in logarithms and degrees of freedom. Thus, to detect a worker urine sample to be above the 58-person "control" population 95 percentile [about 3.2 microBq (85 aCi)] at the 95% probability level (0.05 Type H error) would now require an average of about 11 microBq (300 aCi) per sample, compared to 5 microBq per sample (132 aCi per sample) in a previous paper. This paper presents the algorithms used to obtain the new calibration line and the uncertainty distributions of interpretations at various analyte levels. The importance of maintaining process control over the statistical interpretation of bioassay data as well as for the radiochemical procedures for achieving the lowest feasible level of detection is demonstrated.