H Huschka | PubMed Health

PubMed1998

Laser in situ keratomileusis for hyperopia.

PURPOSE: To examine the initial results of laser in situ keratomileusis (LASIK) for hyperopia. SETTING: Arzt für Augenheilkunde, Mannheim, and Photoingenieur, Wendelstein, Germany. METHODS: This retrospective study evaluated 43 eyes having hyperopic LASIK using the Automatic Corneal Shaper (Chiron Vision) and the MEL 60 excimer laser (model 94, Aesculap-Meditec). Patients were divided into two groups. Group 1 consisted of 20 eyes with a refraction from +1.00 to +4.00 diopters (D) and Group 2, 23 eyes from +4.25 to +8.00 D. Objective refraction and visual acuity were measured over 12 months. RESULTS: One year after LASIK, Group 1 had a mean spherical equivalent of +0.33 D (range -0.79 to +1.45 D) and Group 2, +1.91 D (range -0.08 to +3.71 D). Best corrected visual acuity remained unchanged in 35.0% in Group 1 and 56.5% in Group 2. Five percent in Group 1 and 7.3% in Group 2 lost more than 2 lines of best corrected visual acuity. CONCLUSIONS: Laser in situ keratomileusis for hyperopia resulted in less regression, minimal haze, and better predictability and stability than surface photorefractive keratectomy. Preoperative corneal radius appeared to be an important factor in eyes with high hyperopia.

Adolescent↗

PubMed1985

Evidence for a common siderophore transport system but different siderophore receptors in Neurospora crassa.

Uptake and competition experiments were performed with Neurospora crassa and Penicillium parvum by using 14C-labeled coprogen and 55Fe-labeled ferrichrome-type siderophores. Several siderophores of the ferrichrome family, such as ferrichrome, ferricrocin, ferrichrysin, and tetraglycyl-ferrichrome as well as the semisynthetic ferricrocin derivatives O-(phenyl-carbamoyl)-ferricrocin and O-(sulfanilyl-carbamoyl)-ferricrocin were taken up by N. crassa. The ferrichrome-type siderophores used vary in the structure of the peptide backbone but possess a common lambda-cis configuration about the iron center and three identical ornithyl-delta-N-acetyl groups as surrounding residues. This suggests that these ferrichrome-type siderophores are recognized by a common ferrichrome receptor. We also concluded that the ferrichrome receptor is lambda-cis specific from the inability to take up the synthetic enantiomers, enantio-ferrichrome and enantio-ferricrocin, possessing a delta-cis configuration about the iron center. On the other hand, we found that coprogen, possessing a delta-absolute configuration and two trans-anhydromevalonic acid residues around the metal center, was also taken up by N. crassa and was competitively inhibited by the ferrichrome-type siderophores. We therefore propose the existence of a common siderophore transport system but the presence of different siderophore receptors in N. crassa. In addition, ferrirubin, which is very slowly transported by N. crassa, inhibited both coprogen and ferrichrome-type siderophore transport. Contrary to the findings with N. crassa, transport experiments with P. parvum revealed the presence of a ferrichrome receptor but the absence of a coprogen receptor; coprogen was neither transported nor did it inhibit the ferrichrome transport.

Bacterial Outer Membrane Proteins↗