Construction of an effective host-vector system for the yeast Saccharomyces exiguus Yp74L-3.

An effective host-vector system specific to the yeast Saccharomyces exiguus Yp74L-3 was constructed to promote the molecular genetic analyses for the yeast. To obtain a stable reversionless host strain, we constructed an S. exiguus strain carrying leu2::ScURA3 by disrupting the S. exiguus LEU2 gene with the S. cerevisiae URA3 gene. A vector plasmid unique to S. exiguus was subsequently developed by inserting both the LEU2 gene and an ARS cloned from S. exiguus into an Escherichia coli phagemid, pUC119. The vector constructed, pTH119 was able to transform the S. exiguus leu2::ScURA3 strain to Leu+ efficiently. The stability of the vector in the S. exiguus host cells resembled that of a YRp-type vector in S. cerevisiae.

[Multicenter prospective study of retinopathy of prematurity--II. Optimum timing of the first examination].

We reviewed the records of 360 cases of retinopathy of prematurity (ROP) in 12 institutions in Japan, and investigated the optimum timing of the first examination. On the basis of the onset of ROP and the timing of the first treatment, the first ophthalmological examination should be performed 3 weeks after birth or 29 weeks of postconceptional age at the latest. Regarding the visibility of the fundus, there was little hazy media after 29 weeks of postconceptional age. Under the basic policy that the severe progressive "plus" disease should be properly treated, we concluded that the first ophthalmological examination should be performed 3 weeks after birth at the latest. When the gestational age at birth is less than 26 weeks, funduscopy at the post conceptional age of 29 weeks is advisable.

[Multicenter prospective study of retinopathy of prematurity--III. Timing of the coagulation therapy and the course of retinopathy of prematurity after coagulation].

We reviewed the records of 360 cases of retinopathy of prematurity (ROP) in 12 institutions in Japan, and investigated the timing of the coagulation therapy and the course of ROP after coagulation. The first coagulation therapy was performed at 9.6 weeks after birth and 35.9 weeks of postconceptional age on the average. The severity index in individual infants also showed that the disease became worse during the period from 32 to 36 weeks of postconceptional age. However, the fundus was clearly visible and there was no primary hazy media during this period. On the basis of the results of the timing of the first treatment, the visibility of the fundus, and the severity index in individual infants, we concluded that an ophthalmological examination with special care should be performed during the period from 32 to 36 weeks of postconceptional age.

[Multicenter prospective study of retinopathy of prematurity--IV. Comparison with the data from University of Miami].

We investigated the records of 360 cases of retinopathy of prematurity (ROP) in 12 institutions in Japan (we treated the severe progressive "plus" disease by coagulation therapy), and compared them with data from University of Miami (Ophthalmology 94: 620-629, 1987), as representative of the natural course of ROP without coagulation therapy in those days. The timing of the first examination and the first positive diagnosis were later at University of Miami than in Japan. The time of maximal severity of the disease and occurrence of regression were also later the University of Miami than in Japan. In Japan, the first examination was performed at 29 weeks of postconceptional age or at 3 weeks after birth. At the University of Miami, the first examination was performed at 32 weeks of postconceptional age. If the severe progressive "plus" disease is to be properly treated by photo-coagulation or cryotherapy, it is essential to commence fundus examination earlier.