N-terminal 4-imidazolidinone prodrugs of Leu-enkephalin: synthesis, chemical and enzymatic stability studies.

Four N-terminal 4-imidazolidinone prodrugs of Leu-enkephalin are prepared and characterized. Their enzymatic and chemical stability are assessed using high-performance liquid chromatography. The prodrug derivatives are shown to degrade stoichiometrically to Leu-enkephalin in phosphate buffer [t1/2 (0.05 M phosphate buffer without KCl): acetone prodrug (II) 930 min; cyclopentanone prodrug (III): 216 min; cyclohexanone prodrug (IV): 432 min; 4-methylcyclohexanone prodrug (V): 792 min]. Furthermore, the prodrugs are shown to afford global stabilization of the Leu-enkephalin molecule towards the enzymes, aminopeptidase N and angiotensin converting enzyme, primarily responsible for degradation of Leu-enkephalin at the blood-brain barrier and in plasma. Therefore, the 4-imidazolidinones, being metabolic stable and bioreversible, may be suitable prodrug candidates for delivery of Leu-enkephalin to important target areas such as the brain, if given intravenously.

Effects of topical anandamides on intraocular pressure in normotensive rabbits.

A series of anandamide-type compounds were synthesized and studied for their effect on the intraocular pressure (IOP) of normotensive pigmented rabbits. Each test compound was dissolved in an aqueous 2-hydroxypropyl-beta-cyclodextrin solution and administered (31.25 - 62.5 micrograms) unilaterally to the eye. The most promising anandamides caused a statistically significant reduction of IOP in treated eyes, usually preceded by an initial transient elevation of IOP, compared to saline controls. In the contralateral untreated eyes, only a marginal or short hypotensive response was observed. Indomethacin pre-treatment (12.5 mg, s.c.) eliminated the IOP response to administered anandamides and arachidonic acid.

Maculopathy caused by welding arcs. A report of 3 cases.

It is well known that radiation from welding arcs can cause keratoconjunctivitis and 'glassblower's cataract'. In literature only few cases of welding arc maculopathy have been reported. Three cases are presented.

Intraocular lens prediction and oculometric harmony. With special reference to skew ratios between axial length and corneal curvature radius.

The oculometric features have been analysed in two groups of cataract patients, each comprising 30 subjects. All had undergone ECCE and insertion of biconvex Rayner 2 Superflex posterior chamber IOL. Using Binkhorst and SRK II routinely, the groups were given by a good fit between methods (discrepancy between emmetropia predictions numerically < 1 D) and a poor fit (actual discrepancy range 1.6-4.1 D, all with the same sign, the lower values being predicted by Binkhorst). A certain overlapping between groups was found regarding axial length and corneal curvature radius, the ranges being 21.5-25.1/22.7-29.9 mm and 7.3-8.5/7.2-8.1 mm, respectively. In contrast there was no overlapping regarding the ratio between axial length and corneal curvature radius; the ranges were 2.80-3.05 and 3.06-3.90 in the two groups. Evaluating the actual prediction errors by the two methods (follow-up after at least 4 months), they did not primarily pertain to very short or very long eyes, as usually advanced. Skew ratios between axial length and corneal curvature appeared more decisive. Possible implications for the current IOL prediction formulas, including the newer generations, are discussed.

Birdshot retinochoroidopathy in monozygotic twins.

Birdshot retinochoroidopathy is a rare ocular disorder which was named and delineated as a separate clinical entity by Ryan & Maumenee in 1980. We diagnosed birdshot retinochoroidopathy in a monozygotic pair of twins, who were affected with a time interval of 12 years, respectively. These are the first with birdshot retinochoroidopathy to be reported from the Nordic countries and the first report on this disorder in monozygotic twins. Due to night-blindness, visual field defects and a severely affected electroretinogram one of our cases initially was diagnosed as a choroidoretinal dystrophy. Birdshot retinochoroidopathy should be kept in mind as a differential diagnosis in retinitis pigmentosa-like disorders with widespread choroidal involvement. Our cases substantiated the evidence of a strong correlation with the presence of HLA-A29 antigen.

The new milky way.

Our understanding of the large-scale structure of the Milky Way has undergone considerable revision during the past few years. The Galaxy is larger and much more massive than was previously supposed; the newly discovered mass consists of nonluminous matter which is likely to be the dominant form of matter in the universe. New analyses of the atomic hydrogen gas show that the disk of the Galaxy is about twice as extended as was previously thought. Beyond the sun, the gas is concentrated in large-scale, coherent spiral arms indicative of a regular four-armed spiral pattern. The outer edge of the disk has a remarkable scalloping.