Intraocular pressure, anterior chamber depth and axial length following intravenous mannitol.

The intraocular pressure (IOP), anterior chamber depth (ACD), and axial length (AL) were measured in 38 eyes of 19 subjects before and after intravenous mannitol injection (12.5 g). Intraocular pressures dropped over the initial 30 min then rose back to baseline by 2 hr. Time 0 min:14.2 mmHg, 15 min:12.7 mmHg, 30 min:11.4 mmHg, 60 min:12.0 mmHg, 90 min, 13.2 mmHg, 120 min:14.1 mmHg. Sitting and supine ACD and AL did not change following mannitol injection. This study supports an ocular hypotensive effect of mannitol without reducing vitreous volume using a relatively low dose of mannitol (12.5 g). This finding has important implications for its use in ocular surgery at this dosage.

Witelo--Polish vision scientist of the middle ages: father of physiological optics.

Unknown to the Western hemisphere, a Polish scientist, naturalist, anatomist, physiologist, philosopher and optician, Witelo, wrote an important ten volume manuscript, Peri-Optikes, usually cited in the literature as Perspectiva. This classic textbook was first published in 1535 in Nuremberg under the title: Vitellionis mathematici doctissimi ... vulgo Perspectivam vocant libri X, which is translated to English as Perspectiva. It was a vital source of information for such scientists as Leonardo da Vinci, Keppler and others in the next few centuries. Although many of his ideas were similar to Alhazan's, who earlier had written a significant optical manuscript De aspectibus, Witelo developed his own interpretation of many optical issues. He was one of the first scientists to discover spherical aberration of concave lenses and concave mirrors. He was also first to point out "that deflection of the light ray increases with the angle in which they approach two different optical substances and each increase is smaller than the previous one." Until recently, Witelo's achievements and contributions to the understanding of optical and anatomical aspects of the eye and visual function have remained unknown in western literature. Undoubtedly, Witelo should be recognized as the father of physiological optics.

Secretion of insulin-like growth factor I and its binding proteins by collecting duct cells.

Insulin-like growth factor I (IGF-I) has been found in the kidney, particularly in the collecting duct in the rat. Since cultured rabbit collecting duct cells constitute a convenient system for in vitro studies, we have examined whether these cells secrete IGF-I. Culture medium conditioned by collecting duct cells was concentrated by reverse phase chromatography and applied to a Sephadex G100 column equilibrated in a denaturing buffer. Two major species with apparent molecular weights of 7.5 and greater than 25 kilodaltons (kD) were identified by IGF-I RIA. A smaller amount of 10 kD species was also observed. Further characterization of 7.5 kD IGF-I immunoreactive species by reverse phase HPLC showed that it eluted in a single peak. To determine whether the higher molecular weight species possessed IGF-I binding activity, appropriate fractions were desalted, incubated with [125I]IGF-I (thr59) for two hours at 30 degrees C and applied to a Sephadex G100 column equilibrated in a non-dissociating buffer. The major peak of radioactivity was confined to a high molecular weight region; there was no radioactivity in the fractions corresponding to 7.5 kD. Western ligand analysis of unreduced conditioned medium identified two IGF-I binding species of 25 and 30 kD, similar in size to species observed in normal rabbit serum. 125I-IGF-I binding as assessed in a charcoal adsorption assay could be displaced by IGF-I and IGF-II but not by insulin. Further characterization of the 10 kD peak of IGF-I immunoreactivity indicated that it did not possess IGF-I binding activity.(ABSTRACT TRUNCATED AT 250 WORDS)