Shack-Hartmann-Based wavefront analyzer for calibrating excimer lasers.

PURPOSE: Currently, refractive surgical excimer laser systems are calibrated by ablating plastic lenses, which are measured by lensometer and analyzed by a technician. The accuracy of this method is approximately 0.25 diopters (D) in sphere and cylinder power. Theoretically, objective calibration using wavefront technology would be significantly more accurate, thereby improving surgical outcomes. This study describes a Shack-Hartmann-based instrument, which has been developed to measure ablated plastic lenses for calibration and quality control of the excimer laser. METHODS: A calibration instrument comprising an LED source at 640 nm, a lenslet array, beam-guiding optics, and a CCD camera was designed to perform full wavefront analysis. The measurement plane is conjugate to the lenslet array plane, and the diameter of the pupil is 5 mm. Accuracy was determined by measuring a set of well-calibrated spherical and cylindrical glass lenses. Plastic lenses were ablated, and high-precision measurements were performed by surface profile scanner. RESULTS: In the power range of -6.00 to +4.00 D, repeatability exceeded 0.01 D, accuracy of measurement exceeded 0.04 D, and 10 for the axis of cylinder lenses. The measurement of excimer-ablated plastic lenses agreed with high-precision surface profile scanner measurements within 0.10 D, and repeatability exceeded 0.01 D. CONCLUSIONS: Wavefront technology-based, high-precision measurement of calibration lenses can more accurately set the energy of the excimer laser, which enhances the accuracy of refractive laser correction. In automating calibration, the new instrument removes operator subjectivity and decreases the time needed for calibration.

Differential expression of miR-1, a putative tumor suppressing microRNA, in cancer resistant and cancer susceptible mice.

Mus spretus mice are highly resistant to several types of cancer compared to Mus musculus mice. To determine whether differences in microRNA (miRNA) expression account for some of the differences in observed skin cancer susceptibility between the strains, we performed miRNA expression profiling of skin RNA for over 300 miRNAs. Five miRNAs, miR-1, miR-124a-3, miR-133a, miR-134, miR-206, were differentially expressed by array and/or qPCR. miR-1 was previously shown to have tumor suppressing abilities in multiple tumor types. We found miR-1 expression to be lower in mouse cutaneous squamous cell carcinomas (cSCCs) compared to normal skin. Based on the literature and our expression data, we performed detailed studies on predicted miR-1 targets and evaluated the effect of miR-1 expression on two murine cSCC cell lines, A5 and B9. Following transfection of miR-1, we found decreased mRNA expression of three validated miR-1 targets, Met, Twf1 and Ets1 and one novel target Bag4. Decreased expression of Ets1 was confirmed by Western analysis and by 3' reporter luciferase assays containing wildtype and mutated Ets1 3'UTR. We evaluated the effect of miR-1 on multiple tumor phenotypes including apoptosis, proliferation, cell cycle and migration. In A5 cells, expression of miR-1 led to decreased proliferation compared to a control miR. miR-1 expression also led to increased apoptosis at later time points (72 and 96 h) and to a decrease in cells in S-phase. In summary, we identified five miRNAs with differential expression between cancer resistant and cancer susceptible mice and found that miR-1, a candidate tumor suppressor, has targets with defined roles in tumorigenesis.

Comparison of FT4 with log TSH on the Abbott Architect ci8200: Pediatric reference intervals for free thyroxine and thyroid-stimulating hormone.

BACKGROUND: We evaluated the clinical validity of serum FT4 measurements by assessing its correlation with log TSH. To provide pediatric reference intervals (representative ranges) for FT4, and TSH on the Architect ci8200 integrated system. METHODS: This population-based study encompassed 6023 children (3369 females and 2654 males). The percentile and Hoffmann approaches for obtaining reference intervals on these analytes were also compared. RESULTS: FT4 correlation with log TSH was poor ( r=0.010 for males and 0.050 for females). Reference intervals were established. TSH and FT4 did not show a significant sex difference; moreover, the intervals decreased with age for FT4 and TSH. CONCLUSIONS: Whereas in a previous study ultrafiltration tandem mass spectrometry yielded a correlation of r=0.90 for FT4 vs. log TSH this present study reveals a poor FT4 vs. log TSH correlation in the pediatric population studied and indicates the FT4 immunoassay conducted on the Abbott Architect ci8200 is less useful clinically than might have been expected. Reference intervals using the Hoffmann approach for pediatric in- and out-patients compare well with previously published results utilizing the percentile approach.