High-throughput lensfree imaging and characterization of a heterogeneous cell solution on a chip

A high-throughput on-chip imaging platform that can rapidly monitor and characterize various cell types within a heterogeneous solution over a depth-of-field of approximately 4 mm and a field-of-view of approximately 10 cm(2) is introduced. This powerful system can rapidly image/monitor multiple layers of cells, within a volume of approximately 4 mL all in parallel without the need for any lenses, microscope-objectives or any mechanical scanning. In this high-throughput lensless imaging scheme, the classical diffraction pattern (i.e., the shadow) of each micro-particle within the entire sample volume is detected in less than a second using an opto-electronic sensor chip. The acquired shadow image is then digitally processed using a custom developed "decision algorithm" to enable both the identification of the particle location in 3D and the characterization of each micro-particle type within the sample volume. Through experimental results, we show that different cell types (e.g., red blood cells, fibroblasts, etc.) or other micro-particles all exhibit uniquely different shadow patterns and therefore can be rapidly identified without any ambiguity using the developed decision algorithm, enabling high-throughput characterization of a heterogeneous solution. This lensfree on chip cell imaging platform shows a significant promise especially for medical diagnostic applications relevant to global health problems, where compact and cost-effective diagnostic tools are urgently needed in resource limited settings.     

A spore quality–quantity tradeoff favors diverse sporulation strategies in Bacillus subtilis

Quality–quantity tradeoffs govern the production of propagules across taxa and can explain variability in life-history traits in higher organisms. A quality–quantity tradeoff was recently discovered in spore forming bacteria, but whether it impacts fitness is unclear. Here we show both theoretically and experimentally that the nutrient supply during spore revival determines the fitness advantage associated with different sporulation behaviors in Bacillus subtilis. By tuning sporulation rates we generate spore-yield and spore-quality strategists that compete with each other in a microscopic life-cycle assay. The quality (yield) strategist is favored when spore revival is triggered by poor (rich) nutrients. We also show that natural isolates from the gut and soil employ different life-cycle strategies that result from genomic variations in the number of rap-phr signaling systems. Taken together, our results suggest that a spore quality–quantity tradeoff contributes to the evolutionary adaptation of sporulating bacteria.Subject terms: Bacterial genetics, Biological sciences, Bacterial evolution     

Geometric limit of multiple local Limberg flaps: a flap design.

The Limberg rhombic flap is a reliable and widely used technique in head and neck surgery. Since Limberg introduced his original design in 1946, several modifications of the technique have been described. Although a single Limberg flap is frequently used at the face to close small to medium defects, multi-Limberg flap techniques can help the surgeon to cover moderate to large defects of the extremities, trunk, and back. In this study, a design of four neighboring local Limberg flaps to cover a moderate to large defect without using a skin graft is introduced. It is believed that this design is the geometric limit of multiple Limberg flaps that can entirely cover a single large rhombic defect, because one Limberg flap unit can only be adjoined by three others, one from the tip and two from the sides. This flap design of four local Limberg flaps is also the only geometrically possible design that can keep all the bases of these four flaps free of incisions if one attempts to prepare four small Limberg flaps around a large rhombic defect.     

Pre and postoperative assessment of regional cerebral blood flow in hydrocephalus by 99mTc-hexamethyl-propylenamine oxime SPECT

Cerebrovascular changes resulting from hydrocephalus still remain to be investigated. It has been suggested that hydrocephalus distorts the large feeding arteries and that the collapse of capillaries results in decreased cerebral blood flow. This clinical study was designed to evaluate the effect of shunting on regional cerebral blood flow in patients with obstructive hydrocephalus of varying duration. Technetium-99m hexamethyl propyleamine oxime (99mTc-HMPAO) was used to measure the cerebral perfusion, semiquantitatively, since the pattern of its distribution in brain is somewhat similar to that of regional cerebral blood flow (rCBF), and the pre and postoperative semiquantitative rCBF values of each lobe were calculated. Fifteen patients (8 F, 7 M) underwent both CT and single photon emission tomography (SPECT) using 99mTc-HMPAO examination before and 1 week after shunting. Mean percentage of all lobes were calculated by subtracting the preoperative mean rCBF of all lobes from the corresponding postoperative values. The patients were classified into 3 groups according to the mean percentage of all lobes. Group A: showed a marked increase in mean cortical blood flow (+ 16.00 +/- 2.9%), group B: a moderate increase (11.27 +/- 4.8%), and in group C: there was the least improvement in mean cortical blood flow (+ 1.17 +/- 2.7%). The mean duration of hydrocephalus of group A, group B and group C was 5 +/- 0.5 weeks, 8 +/- 1 weeks and more than 12 weeks, respectively. Psychological testing and clinical observation of the daily activities of the patients postoperatively showed some correlation with increased rCBF and clinical improvement.(ABSTRACT TRUNCATED AT 250 WORDS)