ABSTRACT
SETTING: Hanoi Lung Hospital, Hanoi, Viet Nam. OBJECTIVE: To compare the accuracy of CellScopeTB, a manually operated mobile digital fluorescence microscope, with conventional microscopy techniques. DESIGN: Patients referred for sputum smear microscopy to the Hanoi Lung Hospital from May to September 2013 were included. Ziehl-Neelsen (ZN) smear microscopy, conventional light-emitting diode (LED) fluorescence microscopy (FM), CellScopeTB-based LED FM and Xpert(®) MTB/RIF were performed on sputum samples. The sensitivity and specificity of microscopy techniques were determined in reference to Xpert results, and differences were compared using McNemar's paired test of proportions. RESULTS: Of 326 patients enrolled, 93 (28.5%) were Xpert-positive for TB. The sensitivity of ZN microscopy, conventional LED FM, and CellScopeTB-based LED FM was respectively 37.6% (95%CI 27.8-48.3), 41.9% (95%CI 31.8-52.6), and 35.5% (95%CI 25.8-46.1). The sensitivity of CellScopeTB was similar to that of conventional LED FM (difference -6.5%, 95%CI -18.2 to 5.3, P = 0.33) and ZN microscopy (difference -2.2%, 95%CI -9.2 to 4.9, P = 0.73). The specificity was >99% for all three techniques. DISCUSSION: CellScopeTB performed similarly to conventional microscopy techniques in the hands of experienced TB microscopists. However, the sensitivity of all sputum microscopy techniques was low. Options enabled by digital microscopy, such as automated imaging with real-time computerized analysis, should be explored to increase sensitivity.
Subject(s)
Bacteriological Techniques/instrumentation , Microscopy, Fluorescence/instrumentation , Sputum/microbiology , Tuberculosis, Pulmonary/diagnosis , Adult , Female , Humans , Male , Middle Aged , Mycobacterium tuberculosis , Sensitivity and Specificity , VietnamABSTRACT
An experiment quantified the effect of food ration and spawning number on the breeding season reproductive performance of batch-spawning, female three-spined sticklebacks Gasterosteus aculeatus. Individually housed females were maintained on fixed rations of 2, 4, 8 or 16% of their initial postspawning mass of live enchytraeid worms from immediately after their first spawning until they ceased spawning. Number of spawnings correlated positively with ration. Total breeding season reproductive investment (total wet mass of eggs produced as a percentage of initial postspawning female mass) ranged from 38% at the 2% ration to 147% at the 16% ration. At the lower rations, postspawning mass, batch fecundity and wet and dry masses of the batch declined over successive spawnings, with the rate of decline inversely related to ration. At the highest ration, there was no decline in batch fecundity and postspawning mass increased over successive spawnings. Mean reproductive investment per inter-spawning interval was higher at the highest ration, but at all rations declined over successive spawnings. Mean reproductive effort per inter-spawning interval (wet mass of eggs spawned as a percentage of the wet mass of food consumed over the inter-spawning interval) was inversely related to ration. At the higher rations, reproductive effort showed no trend over successive spawnings. Neither spawning number nor ration had a systematic effect on egg diameter, wet mass per egg, dry mass per egg or total lipid content of the eggs. If the rate of food intake was insufficient, although batch fecundity declined, the main adjustment was a reduction in the number of spawnings in the breeding season.
Subject(s)
Reproduction/physiology , Smegmamorpha/physiology , Animals , Eggs , Female , MaleABSTRACT
Giardia lamblia cell populations show 90% detachment from glass under normal forces of 2.43+/-0.33 nN applied by centrifugation. Detachment forces were not significantly different for cells attached to positively charged, hydrophobic, or inert surfaces than for cells attached to plain glass. The insensitivity of attachment force to surface treatment is consistent with a suction-based mechanism of attachment.
Subject(s)
Giardia lamblia/drug effects , Giardia lamblia/physiology , Glass , Polyethylene Glycols/pharmacology , Animals , Cell Adhesion/physiology , Centrifugation , Stress, Mechanical , Surface PropertiesABSTRACT
Light focused from air into a spherical microlens is affected by diffraction at the lens surface as its diameter approaches the wavelength of light. Through an extension of Mie theory, we show that a converging wave that is incident upon a Si microlens with a diameter less than approximately 4lambda creates a spot as much as 25% smaller than predicted with vector diffraction theory. Si microlenses only a wavelength in diameter are shown to be virtually insensitive to variations in the maximum illumination angle, and changes in index of refraction are not found to cause the proportional changes in spot size that would be expected from vector diffraction theory.