Quantification of refractive error: comparison of autorefractor and focometer.

PURPOSE: The advantages of a focometer (FOCOMETER) over other methods of refraction for use in developing countries are that it is lightweight, compact, relatively inexpensive, fairly quick, and easy to use with minimal training. This clinical trial compared the repeatability, validity, and ease of use of the focometer with an autorefractor. METHODS: The refractive status of the right eye of 80 participants was determined with an autorefractor (Canon RK3). Three measurements were also taken with the focometer. RESULTS: The spherical equivalent (M) of the focometer was 0.25 D more positive than the autorefractor (p < 0.001) and 84% of measurements were within 0.75 D of the autorefractor. The autorefractor detected astigmatism in 91% (73) of the eyes, whereas the focometer identified only 32% (26). The design of the clock target restricts cylinder axis accuracy to the nearest 15 degrees . There was evidence of a learning effect for the focometer: the second and third measurements were more repeatable in the untrained group. There were no differences between the mean (1.03 +/- 2.28) and third focometer (-1.05 +/- 2.32) measurements (p = 0.34). However, using the third focometer measurement, 94% of participants had visual acuities of at least 6/12(-2). CONCLUSIONS: This study highlighted the focometer's restricted power range, inaccuracy of astigmatism and axis determination, and dependence on subject understanding and compliance. Therefore, in most clinical settings, the focometer would not be adequate for quantifying refractive error, but the focometer spherical equivalent was within acceptable limits of the autorefractor, and the visual acuity with lenses determined by the focometer indicates its potential usefulness in public health settings, especially where only spherical ready-made spectacles are dispensed. There may be more cost-effective ways to determine refractive error in these circumstances. A potentially important enhancement in focometer methodology that improves its ease of use was identified: use only the third measurement for each eye.     

Fatigue and breastfeeding: an inevitable partnership?

Postpartum fatigue is a normal condition that most women experience. Breastfeeding is often associated in women's minds as contributing to the feeling of overall perceived fatigue, and many women indicate that they have ceased breastfeeding because of fatigue. However, the relationship between feeding choice and perceived fatigue has never been established. Two hundred and fifty-three women participated in a study examining whether perceived fatigue differed for bottle-feeding and breastfeeding women at 3 different times during the postpartum period (2-4 days, 6 weeks, and 12 weeks postpartum). Results showed no significant differences for these 2 groups, suggesting that perceived fatigue during the postpartum period is not dependent on feeding choice. Additional analyses examining other variables with a potential effect were nonsignificant. Because perceived physical fatigue does not appear to be dependent on feeding choice, women should be prepared for the feeling of perceived fatigue during the postpartum period while at the same time be reassured that feeding choice is not correlated.     

CD44 ligation induces apoptosis via caspase- and serine protease-dependent pathways in acute promyelocytic leukemia cells.

We have recently reported that ligation of the CD44 cell surface antigen with A3D8 monoclonal antibody (mAb) triggers incomplete differentiation and apoptosis of the acute promyelocytic leukemia (APL)-derived NB4 cells. The present study characterizes the mechanisms underlying the apoptotic effect of A3D8 in NB4 cells. We show that A3D8 induces activation of both initiator caspase-8 and -9 and effector caspase-3 and -7 but only inhibition of caspase-3/7 and caspase-8 reduces A3D8-induced apoptosis. Moreover, A3D8 induces mitochondrial alterations (decrease in mitochondrial membrane potential DeltaPsi m and cytochrome c release), which are reduced by caspase-8 inhibitor, suggesting that caspase-8 is primarily involved in A3D8-induced apoptosis of NB4 cells. However, the apoptotic process is independent of TNF-family death receptor signalling. Interestingly, the general serine protease inhibitor 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF) decreases A3D8-induced apoptosis and when combined with general caspase inhibitor displays an additive effect resulting in complete prevention of apoptosis. These results suggest that both caspase-dependent and serine protease-dependent pathways contribute to A3D8-induced apoptosis. Finally, A3D8 induces apoptosis in all-trans-retinoic acid-resistant NB4-derived cells and in APL primary blasts, characterizing the A3D8 anti-CD44 mAb as a novel class of apoptosis-inducing agent in APL.     

Blood velocity assessment using 3D bright-blood time-resolved magnetic resonance angiography.

Blood velocity is a functional parameter that is not easily assessed noninvasively, especially in small animals. A new noninvasive method that uses magnetic resonance angiography (MRA) to measure blood flows is proposed. This method is based on the time-of-flight (TOF) phenomenon. By initially suppressing the signal from the stationary spins in the area of interest, it is possible to sequentially visualize only the signal from the moving spins entering a given volume. With this method, 3D cine images of the blood flow can be generated by positive contrast, with unparalleled spatial (<200 microm) and temporal resolutions (<10 ms/image). As a result, it is possible to measure flow in sinuous paths. The present method was applied in vivo to measure the blood velocity in mouse carotid arteries. Because of its robustness and simplicity of implementation, this method has numerous potential applications for fundamental studies in small animal models.     

Behavioral measurement of axonal thresholds

A behavioral method for measuring the electrical sensitivity of directly stimulated elements in the brain is described and applied to the medial forebrain bundle (MFB) reward path and the tectospinal circling path. Equations are derived from which threshold current densities may be calculated from knowledge of the electrode tip dimensions and the current required to produce criterion behavior, which is a function of electrode size. Four different sizes of electrode were implanted in the MFB of rats and self-stimulation rates plotted against stimulating current. The mean currents for criterion bar-pressing rates of 25% and 55% of maximum rate were determined for each electrode size and the values used to calculate average threshold current densities. Two sizes of electrode were implanted in the tectospinal tract of rats and the average currents to produce circling at 0.2 and 0.4 turns/s were measured. The threshold current densities for self-stimulation axons were about 5 times as large as those for circling, in accordance with other evidence that tectal circling path axons are larger than those of the MFB reward path.