Evaluation of current techniques of corneal epithelial removal in hyperopic photorefractive keratectomy

PURPOSE: To determine the efficacy of 3 current methods used to remove corneal epithelium prior to photorefractive correction of hyperopia and to compare clinical data in patients who had rotary brush or blunt scrape epithelial removal in the treatment of hyperopic photorefractive keratectomy (PRK). SETTING: University of Ottawa Eye Institute, Ottawa General Hospital, Ottawa, Ontario, Canada. METHODS: The epithelium from human eye-bank eyes was removed using a Paton spatula, 15% alcohol, and the Amoils rotating plastic brush. The effects were examined by scanning and transmission electron microscopy. Twelve month postoperative data were obtained on 25 eyes with refractions of +1.00 to +4.00 diopters (D) that had been treated for hyperopia with the VISX Star excimer laser, using blunt scrape or the rotary brush to remove the corneal epithelium. RESULTS: All 3 methods effectively removed corneal epithelium. The Paton spatula, however, left small nicks in Bowman's layer. Both the rotating brush and alcohol debridement left Bowman's layer intact. Alcohol treatment required follow-up epithelial debris removal, while brushing left minimal amounts of debris. There was a strong trend toward rapid epithelial healing in the brushed corneas compared with the scraped ones, but this was not statistically significant. Clinically, at 12 months postoperatively, brushed corneas showed a trend toward more superior outcomes than scraped corneas in actual refractive outcome, uncorrected visual acuity (UCVA), lines of UCVA gained, and predictability of the desired outcomes. However, only the outcome in UCVA of 20/40 or better and the decreased incidence of haze in the brushed corneas over scraped ones were statistically significant. CONCLUSIONS: Both alcohol and the rotating brush provide a quick, effective means of removing the corneal epithelium with minimal risk of damage to Bowman's layer. In our experience, the brush technique was as effective as and possibly superior to the blunt scrape for epithelial removal in hyperopic PRK.     

Cataract extraction rates in Olmsted County, Minnesota, 1980 through 1994

Management of Q-wave acute myocardial infarction (AMI) has been shown to differ between the United States and Canada, with more catheterization and revascularization procedures performed in the United States, but with little or no apparent difference in clinical outcomes. No previous studies have evaluated management differences for the acute coronary syndromes of unstable angina pectoris and non-Q-wave AMI. We therefore compared treatments and outcomes between 14 United States and 4 Canadian tertiary care centers participating in an observational registry of all consecutive admissions for unstable angina or non-Q-wave AMI between 1990 and 1993. A random, stratified sample was selected for detailed assessment and follow-up. There were 1,733 patients enrolled in United States centers and 642 in Canadian ones. In United States centers patients were less likely to receive intravenous nitroglycerin, heparin, beta blockers, calcium antagonists, or > or = 2 anti-ischemic agents. Coronary arteriography during index hospitalization was equally frequent in both countries (63.4% vs 66.9%, p = 0.781), but at 6 weeks and 1 year coronary arteriography was slightly less frequent in the United States patients. Revascularization by coronary angioplasty or bypass surgery was equivalent at 6 weeks and 1 year; however, there were trends toward less angioplasty and more bypass surgery in the United States than in Canada. Patients at United States centers stayed in the hospital fewer days than patients at Canadian centers (mean 8.2 vs 12.1 days, p <0.001). Death or AMI by 6 weeks was not different (4.8% vs 4.4%, p = 0.633), nor was it different at 1 year (10.0% vs 10.2%, p = 0.836). The combined outcome of death, AMI, or recurrent ischemia was more common in United States than in Canadian patients at 6 weeks (18.4% vs 13.9%, p = 0.004). Our findings indicate that United States physicians and hospitals did not consistently utilize more resources and were not more aggressive than their Canadian counterparts when treating acute coronary syndromes during this period.     

Structural and electrical studies of alternating layers of porphyrins and fatty acids

Langmuir-Blodgett multilayers were formed by the alternate deposition of amphiphilic derivatives of mesoporphyrin IX and protoporphyrin IX and of various fatty acids. These films were studied by low angle X-ray diffraction, scanning electron microscopy and by conductivity measurement in the plane of the film. It is shown that, in the case of diol porphyrin derivatives, a well-ordered superlattice is produced. In contrast, the use of diesters leads to the segregation of the two materials in the plane of the film. Such segregation implies the diffusion of molecules after deposition over distances of the order of 1 μm.     

A literary guide for psychologists.

Recently, while visiting another science laboratory the author was given a glossary of phrases commonly used in scientific reports. Sure that all psychologists who read and write research reports are interested in maximizing "communication," the author cheerfully offers an abridged guide for use with psychological literature. Perhaps other psychologists can suggest additional definitions which will increase enlightenment. An example: What he said: "It has long been known that . . ." and what he meant: "I haven't bothered to look up the original reference but . . .." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polymer-supported syntheses of oxo-crown ethers and derivatives containing α-amino-acid residues

A simple polymer-supported cyclization–cleavage method is described for the small-scale synthesis of macrocyclic oligomers, with from 12 to 18 ring atoms per repeat unit, which are either 2-oxo-crown ethers, or derivatives containing, except in one case, chiral α-amino-acid residues. In each case the major cyclic product was isolated and characterized. In all except one case this was the cyclic monomer. If the macrocyclic oligomers are needed either for the preparation of static or dynamic combinatorial libraries or for entropically-driven ring-opening polymerizations, all members of the family are of interest as they all react through equilibration to give the same final products.     

Locus of control in childhood hyperactivity.

Compared to 16 8–12 yr old normal males, 16 age-matched hyperactive males were more external as determined by scores on the Nowicki-Strickland Locus of Control Scale. The measurement of locus of control in a hyperactive population provides useful information about how hyperactive children compare to others in their expectancies concerning the link between environmental stimuli and their consequences. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polysaccharides of the cocoa pod husk

Cocoa pod husk from Ghana was extracted successively with hot water, hot 0·5% anmonium oxalate, cold 10% potassium hydroxide, and hot 20% sodium hydroxide, and the various polysaccharide fractions isolated after dialysis. The hot-water-soluble fraction was examined by hydrolysis with 50% formic acid, quantitative determination of the component sugars, and characterisation of the sugars by preparation of crystalline derivatives. The major part of this fraction is a pectic material containing D-galacturonic acid, D-galactose, L-rhamnose and L-arabinose, but is contaminated with several other polysaccharides, notably a glucan and a mannan. The ammonium oxalate fraction is also a pectin but in a depolymerised form, while the main component sugar of the alkaline extracts is xylose. The insoluble husk residue is probably chiefly cellulose.     

Low-cost digital system for control of a retarding potential energy analyzer

A simple, low-cost digital system is described which is used in conjuction with a conventional retarding potential analyzer to measure the energy distribution of the electrons in a beam.