Inhibitory effects of alloxan on mammalian adenyl cyclase.
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Adenine Nucleotides↗
Biomedical subjects
K L Cohen
Publications and source records attributed to K L Cohen.
Efficacy of glyburide in diabetics poorly controlled on first-generation oral hypoglycemics.
Twenty-four type II (non-insulin-dependent) diabetic patients poorly controlled on maximum doses of first-generation oral hypoglycemic agents were switched to glyburide. There was a significant decrease in glycosylated hemoglobin, but the level was normalized in only four patients; there was no correlation with age, weight, or duration of diabetes. The best predictor for improvement was initial failure on tolbutamide, as opposed to the other first-generation drugs. Patients not controlled with 500 mg/day of chlorpropamide were less likely to benefit from glyburide therapy.
Administration, Oral↗
Isolated, bilateral orbital mass lesions during childhood.
A 9-year-old female developed bilateral orbital masses over four months without associated orbital inflammation or systemic disease. Orbital biopsy documented an unusual presentation of childhood pseudotumor. Nine days following surgery orbital inflammatory signs appeared suddenly and involved both the unoperated and biopsied orbits equally. These orbital lesions resolved completely after three months of systemic corticosteroid therapy. The sudden and progressive development of palpable bilateral orbital mass lesions rarely occurs in children without readily identifiable systemic disease. The 9-year-old girl described herein acquired bilateral orbital space-occupying lesions without evidence of ocular, orbital, or systemic abnormalities.
Adrenal Cortex Hormones↗
Microwave thermal keratoplasty for myopia: keratoscopic evaluation in porcine eyes.
PURPOSE: Microwave thermal keratoplasty applies microwave energy to elevate the temperature of the paracentral stroma of the cornea to its thermal shrinkage temperature of about 60 degrees C. A suitable pattern of shrinkage in the paracentral cornea can flatten the central cornea. A surface cooling system preserves the epithelium during the procedure. METHODS: Fourteen enucleated porcine eyes were treated with a prototype microwave thermal keratoplasty applicator that heated in a ring pattern with inner diameter of 3.2 mm and width of 0.7 mm. The change in corneal power was quantified by a videokeratoscope. Slit-lamp microscope examinations and histological assessments were made. RESULTS: The 3-mm simulated keratometry reading showed an average of 6.60+/-6.00 D (standard deviation) of flattening. The region of opacity associated with shrinkage extended to 62% (+/-26%) of the corneal thickness. The epithelium was intact in all eyes. CONCLUSIONS: Microwave thermal keratoplasty applied in the paracentral cornea may flatten the central cornea.
Animals↗
Cat keratoplasty wound healing and corneal astigmatism.
BACKGROUND: A major contributor to postkeratoplasty astigmatism may be donor/recipient disparity. Deficient or excess cornea at the wound is thought to influence the directions of the steep and flat meridians. Using an established model of penetrating keratoplasty in the cat, this study evaluated the morphometry of histopathologic wound features in the steep and flat meridians. METHODS: Thirteen cats had successful penetrating keratoplasties after intentionally misshapen donor corneas were misaligned in misshapen recipient beds. At 9.50 +/- 0.32 (mean +/- 1 SEM) months after keratoplasty, photokeratography was performed and analyzed, corneas were sectioned along the steep and flat meridians, and four histologic sections were processed. Features of the wounds were measured using a Zeiss Videoplan. The relationships between the morphometry of each feature and every other feature, between the morphometry of each feature and eccentricity, and between the steep and flat section morphometry of each feature were statistically evaluated. RESULTS: Epithelial thickness, area of lamellar alteration, length of Descemet's membrane produced postoperatively, and the depth that preoperative Descemet's membrane was embedded in the stroma were correlated with eccentricity (corneal astigmatism). Stromal thickness and the presence or absence of folded and fragmented Descemet's membrane were not correlated with eccentricity. Wound morphometry at the steep meridians was neither correlated with nor significantly different from wound morphometry at the flat meridians. CONCLUSIONS: Differences between healing at the steep and flat meridians were not likely contributors to astigmatism. Disproportionate availability of tissue in wound regions may have affected healing throughout the entire wound over time. The absence of Bowman's layer in cats restricts application of our results to understanding the etiology of corneal astigmatism after penetrating keratoplasty in humans.
Animals↗
Prospective analysis of photokeratoscopy for arcuate keratotomy to reduce postkeratoplasty astigmatism.
Seven eyes of seven patients with visually disabling postkeratoplasty astigmatism underwent arcuate keratotomy to reduce astigmatism. Keratotomy length was prospectively determined by comparing the corneal shape change needed by each patient with shape changes in cadaver eyes induced by arcuate keratotomy. Keratograph ring ovality quantified corneal shape change. Keratotomies were placed in the wound interface using a diamond knife with blade length set to 100% of corneal thickness. Prekeratotomy keratometric astigmatism was 9.27 +/- 2.14 D (mean +/- SD), and at 2.0 to 18.4 months after keratotomy, astigmatism was 2.75 +/- 2.25 D (mean +/- SD). All corneas had decreased keratometric astigmatism and less oval keratoscope rings. Five corneas had 3.00 D or less residual keratometric astigmatism. Change in ring ovality was significantly correlated with keratotomy length and keratometric astigmatism change. The utility of keratoscope ring ovality as a corneal topography metric was demonstrated by systematically investigating the response to arcuate keratotomy.
Adult↗
Unreliability of radiodilution assays as screening tests for cobalamin (vitamin B12) deficiency.
Recent studies have demonstrated problems with the radiodilution assay method for measuring serum cobalamin (vitamin B12) levels. We have found the standard commercial radiodilution kit assay to be totally ineffective in screening for cobalamin deficiency. In a four-month period, 352 patients were screened in a routine clinical laboratory using this kit. None of the serum samples yielded a result below the given normal range of 200 to 1,100 pg/mL. However, when 42 patients with low-normal serum cobalamin levels (200 to 500 pg/mL) were retested by a combination of a modified radiodilution kit, a human intrinsic factor assay, and a microbiological (Lactobacillus leichmannii) assay, 16 (36%) were identified as having serum cobalamin levels that were abnormally low. The diagnosis of cobalamin deficiency may have been incorrectly dismissed in many patients on the basis of test results obtained with these kits, which are in widespread use.
Aged↗