Intrastromal epithelial accretion follows deep excimer annular keratectomy

The purpose of this study was to evaluate corneal reepithelialization and wound healing following annular excimer keratectomy. Two sets of experiments were performed on 35 rabbit eyes. In the first set of experiments, experiment I, deep Fresnel excimer keratectomy was performed, with a 6-mm outer and 3-mm inner diameter. Animals were sacrificed at 1, 5, 12, and 16 weeks, and corneas were examined by light and electron microscopy. In experiment II, the central epithelium was left intact, and superficial and deep mid-peripheral excimer annular keratectomies were performed measuring 6 mm in outer and 3 mm in inner diameter. Animals were sacrificed at 1 week, and corneas were examined by light microscopy. Following deep Fresnel excimer keratectomy (experiment I), corneas showed stromal edema in the central 3-mm zone. Intrastromal islands of epithelial cells with PAS positive basement membrane-like structures were seen histologically at 1 week. Electron microscopy showed loss of stromal collagen in areas adjacent to epithelial islands; in areas distant from the epithelial islands, the stromal collagen appeared normal. The overlying central stroma sloughed after 5 weeks. Anterior stromal scarring was observed. In experiment II (mid-peripheral annular keratectomy), intrastromal epithelial accretion was present in corneas with deep annular keratectomy but not in superficial annular keratectomy. Intrastromal epithelial accretion follows deep excimer annular keratectomy and is associated with adjacent stromal degradation.     

The alpha 1E calcium channel exhibits permeation properties similar to low-voltage-activated calcium channels

The physiological and pharmacological properties of the alpha 1E calcium (Ca) channel subtype do not exactly match any of the established categories described for native neuronal Ca currents. Many of the key diagnostic features used to assign cloned Ca channels to their native counterparts, however, are dependent on a number of factors, including cellular environment, beta subunit coexpression, and modulation by second messengers and G-proteins. Here, by examining the intrinsic pore characteristics of a family of transiently expressed neuronal Ca channels, we demonstrate that the permeation properties of alpha 1E closely resemble those described for a subset of low-threshold Ca channels. The alpha 1A (P-/Q-type), alpha 1B (N-type), and alpha 1C (L-type) high-threshold Ca channels all exhibit larger whole-cell currents with barium (Ba) as the charge carrier as compared with Ca or strontium (Sr). In contrast, macroscopic alpha 1E currents are largest in Sr, followed by Ca and then Ba. The unique permeation properties of alpha 1E are maintained at the single-channel level, are independent of the nature of the expression system, and are not affected by coexpression of alpha 2 and beta subunits. Overall, the permeation characteristics of alpha 1E are distinct from those described for R-type currents and share some similarities with native low-threshold Ca channels.     

Clinical assessment of left ventricular regional contraction patterns and ejection fraction by high-resolution gated scintigraphy

An improved, noninvasive, radionuclidic, gated blood-pool imaging technique has been developed for clinical analysis of regional contraction abnormalities of the left ventricle and determination of ejection fraction. The principal innovations include high-resolution collimation, higher information density, improved method for dynamic aortic-mitral-diaphragmatic border delineation, accurate selection of the endsystolic gating interval through the use of the phonocardiogram, and accurate end-diastole by on-line gating immediately following the electrocardiographic QRS. The results of scintigraphic studies were compared with selective radiopaque cineangiographic findings in 27 patients with cardiac disease; excellent correlations of ejection fractions (r = 0.93) and abnormal contraction patterns (17/17 patients) were demonstrated. In addition, the clinical usefulness in evaluating ventricular performance was demonstrated in 79 patients with acute and chronic coronary artery disease. This radionuclidic technique allowed assessment of reversibility of segmental dyssynergy by the response to nitroglycerin in 20 patients. These findings demonstrate the validity of this improved radionuclidic technique in the atraumatic quantification of ventricular function and suggest its usefulness in a variety of clinical conditions.