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.     

Experimental reproduction and antibody inhibition of marble spleen disease of pheasants

An extract of spleens from three pheasants affected with marble spleen disease was used as an intravenous inoculum to transmit the disease to pen reared pheasants (Phasianus colchicus x Phasianus torquatus). The disease was prevented by specific convalescent pheasant antiserum and by antiserum from turkeys that had recovered from hemorrhagic enteritis of turkeys. The causative agent of the disease passed through 0.22 mu filters, resisted chloroform and retained its precipitin antigen quality after propagation by bird passage. Filterability, chloroform resistance, antigenic characteristics and in vivo response to antibody strongly indicate that the causative agents of marble spleen disease is a virus very similar to the virus which causes hemorrhagic enteritis of turkeys.     

Lectins as probes of chromatin structure. Binding of concanavalin A to purified rat liver chromatin

Concanavalin A (Con A) binds specifically to rat liver chromatin. The extent of binding is directly proportional to both chromatin and concanavalin A concentration. It is reversible and inhibited by specific sugars for which concanavalin A has a binding site. Scatchard analysis reveals the presence of one type of Con A-binding site, with an apparent dissociation constant of 3 X 10(-7) M. A maximum of 10 pmol of Con A binds to 10 microgram of chromatin, indicating an average of one binding site/1400 base pairs of DNA. To identify the polypeptide chains which contain Con A-binding sites, chromosomal proteins were separated by electrophoresis on polyacrylamide gels containing sodium dodecyl sulfate. Con A receptors were localized by incubating the gel in 125I-Con A and subsequent autoradiography. Three major polypeptide bands which bind Con A were identified among the nonhistone chromosomal proteins. The apparent molecular weights of these glycoproteins are 135,000, 125,000, and 69,000. We suggest that lectins may serve as probes for the study of the organization of specific components in chromatin.     

Response of the primate secretory endometrium to subchronic hypercortisolemia

OBJECTIVE: To assess the impact of subchronic and moderate hypercortisolism on the secretory endometrium of the cynomolgus monkey. METHODS: Osmotic pumps containing hydrocortisone phosphate (HP) were implanted subcutaneously in each monkey on the first day of the menstrual cycle; each monkey also received pumps containing saline in another cycle. Blood was obtained three times per week and urine was collected daily for hormone analyses. Endometriectomy was performed 13 +/- 1 days after the serum estradiol (E2) peak in each study cycle. RESULTS: Infusion of HP elevated serum cortisol levels by an average of 70%. Mean serum progesterone (P) levels were decreased by 50% during the secretory phase of HP-treatment cycles by comparison with self-control cycles (P < .01); as a result, the mean endometrial glycogen concentration was reduced by 30% (P < .05) and the activity of 17 beta-hydroxysteroid dehydrogenase was decreased by 70% (P < .05). Serum E2 levels were not consistently elevated by HP treatment, but cytosolic estrogen receptor levels of the endometrium were decreased by 50% (P < .01), indicating increased estrogenic stimulation. Histologic development of the secretory endometrium was retarded, but the length of the secretory phase was not affected by the treatment. CONCLUSION: A moderate elevation of serum cortisol levels over one menstrual cycle consistently produced a reduction in serum P and a hypoprogestogenic-hyperestrogenic response of the secretory endometrium in the cynomolgus monkey.