Effect of retinopathy of prematurity on resolution acuity development in 1- to 3-year-old children.

PURPOSE: To assess the pattern of visual development in children aged 1-3 years with stage 1-3 retinopathy of prematurity (ROP). METHODS: One hundred forty-four infants weighing <1500 g were divided into three groups according to ROP stage. Randomly chosen preterm infants were the controls. Ophthalmic examinations started 4-7 weeks after birth and were performed until the retina was fully vascularized or until any ROP that had developed resolved. Preferential looking acuity measurements were carried out at 12, 18, 24, and 36 months of age. RESULTS: Infants with stage 1-2 or no ROP showed evidence of improving acuity development after 12 months. Infants with stage 3 ROP had significantly lower acuity scores compared to infants with stage 1-2 or no ROP at the 18- and 24-month follow-up examinations (P<.001). At 36 months, the visual acuity of infants with stage 3 ROP showed evidence of improving development but still lagged behind infants with stage 1-2 or no ROP. CONCLUSION: Although mild ROP does not seem to have a considerable effect on the development of resolution acuity until age 3, severe forms of ROP may be associated with impaired visual development, which strongly suggests the necessity of periodic monitoring of early visual acuity in infants with ROP.

[Four newborns with retinopathy similar to oxygen-induced retinopathy].

We report 4 fullterm newborns who developed retinopathy similar to oxygen-induced retinopathy after high concentration oxygen therapy for pneumothorax and emphysema. Two of them had a severe condition, showing marked dilatation, winding, and abnormal branching of the retinal vessels, especially veins, and retinal trubidity. Comparison between the 4 patients and controls without such retinopathy suggested that factors such as the oxygen concentration, the duration of oxygen therapy, the gradual reduction method, and the high level and changes in PaO2 were involved in the development of the retinopathy. Even in fullterm infants, treatment should be performed with consideration of the possible occurrence of changes in the eye fundus.

Diffusion tensor tractography of the Meyer loop in cases of temporal lobe resection for temporal lobe epilepsy: correlation between postsurgical visual field defect and anterior limit of Meyer loop on tractography.

BACKGROUND AND PURPOSE: Visual field defects sometimes occur after temporal resection surgery. Our purpose was to evaluate the correlation between visual field defects caused by temporal lobe resection and the degree of resection of the Meyer loop, as assessed by diffusion tensor tractography. MATERIALS AND METHODS: We examined 14 patients who underwent temporal resection for temporal lobe epilepsy. We obtained presurgical tractographies and then measured the distance between the temporal tip and the anterior limit of the Meyer loop (T-M distance). The degree of resection of the Meyer loop was defined as the distance from the anterior limit of the Meyer loop to the posterior limit of the temporal lobe resection (M-R distance). This was calculated by subtracting the T-M distance from the measured distance between the temporal tip and the posterior limit of the resection (T-R distance). RESULTS: The mean T-M distance was 36.6 mm. The interindividual variation of the distance ranged from 30.0 to 43.2 mm. Although there was no statistically significant correlation between the extent of the visual field defect and the T-R distance, there was a statistically significant correlation between the degree of the visual field defect and the M-R distance. CONCLUSION: The range of interindividual variation for the position of the Meyer loop was rather large, indicating that this variation is the key factor in visual field defects after temporal lobectomy, and the visual field defect appears to be predicted by presurgical tractography. Evaluation of the Meyer loop through the use of tractography seems to be a feasible method, which can be used to predict the visual field defect after temporal lobe resection.

Structural and functional characterization of two wheat histone H2B promoters.

Two wheat histone H2B genes (TH123 and TH153) were isolated. Nucleotide sequence analysis revealed that some characteristic sequence motifs were conserved in both the 5'- and 3'-flanking regions. A canonical TATA box and several CCAAT sequences were present in the presumed promoter regions. Motifs similar or identical to the hexamer (ACGTCA) and octamer (CGCGGATC) motifs that are positive cis-acting elements of the wheat H3 (TH012) promoter were also observed in both the H2B promoters. A gel mobility shift assay indicated that the hexamer and hexamer-like motifs bound the wheat bZIP proteins HBP-1a and/or HBP-1b in vitro. A novel sequence motif, (A/T)(G/A)AAAT(A/G), was found downstream of a translational stop codon as observed in several plant histone H2B cDNAs. Promoter activity was analyzed with H2B promoter-GUS fusion genes in the transient system using tobacco protoplasts. Studies of the promoter function in transgenic tobacco plants showed that the H2B promoters were preferentially active in meristematic tissues. Taken together, our data indicate that the H2B genes are regulated, in part, by the same mechanism as found in H3 and H4 gene transcription.

The relationship between amide proton chemical shifts and secondary structure in proteins.

The parameters for HN chemical shift calculations of proteins have been determined using data from high-resolution crystal structures of 15 proteins. Employing these chemical shift calculations for HN protons, the observed secondary structure chemical shift trends of HN protons, i.e., upfield shifts on helix formation and downfield shifts on ß-sheet formation, are discussed. Our calculations suggest that the main reason for the difference in NH chemical shifts in helices and sheets is not an effect from the directly hydrogen-bonded carbonyl, which gives rise to downfield shifts in both cases, but arises from an additional upfield shift predicted in helices and originating in residues i-2 and i-3. The calculations also explain the well-known relationship between amide proton shifts and hydrogen-bond lengths. In addition, the HN chemical shifts of the distorted amphipathic helices of the GCN4 leucine zipper are calculated and used to characterise the solution structure of the helices. By comparing the calculated and experimental shifts, it is shown that in general the agreement is good between residues 15 and 28. The most interesting observation is that in the N-terminal half of the zipper, although both calculated and experimental shifts show clear periodicity, they are no longer in phase. This suggests that for the N-terminal half, in the true average solution structure the period of the helix coil is longer by roughly one residue compared to the NMR structures.

Regulation of histone gene expression during the cell cycle.

The steady-state level of histone mRNAs fluctuates coordinately with chromosomal DNA synthesis during the cell cycle. Such an S phase-specific expression pattern results from transcriptional activation of histone genes coupled with the onset of replication and from transcriptional repression of the genes as well as specific destabilization of histone mRNAs around the end of the S phase. Proliferation-coupled and S phase-specific expression of histone genes is primarily achieved by the activities of the proximal promoter regions, where several conserved cis-acting elements have been identified. Among them, three kinds of Oct-containing composite elements (OCEs) play a pivotal role in S phase-specific transcriptional activation. Other ones, such as Nona, solo-Oct, and CCGTC motifs, appear to modulate the functions of OCEs to enhance or repress the transcriptional level, possibly depending on the state of the cells. Here, we review the growing evidence concerning the regulatory mechanisms by which plant histone genes are expressed S phase-specifically in proliferating cells.

Identification of three kinds of mutually related composite elements conferring S phase-specific transcriptional activation.

Conservation of the Oct motif (CGCGGATC) is a remarkable feature of plant histone gene promoters. Many of the Oct motifs are paired with a distinct motif, Hex, TCA or CCAAT-box, constituting the type I element (CCACGTCANCGATCCGCG), type II element (TCACGCGGATC) and type III element (GATCCGCG-N14-ACCAATCA). To clarify the roles of these Oct-containing composite elements (OCEs) in cell cycle-dependent and tissue-specific expression, we performed gain-of-function experiments with transgenic tobacco cell lines and plants harboring a derivative of the 35S core promoter/beta-glucuronidase fusion gene in which three or four copies of an OCE had been placed upstream. Although their activities were slightly different, results showed that each of the three types of OCEs could confer the ability to direct S phase-specific expression on a heterologous promoter. In transgenic plants, the type I and III elements exhibited a similar activity, directing expression in meristematic tissues, whereas the activity of the type II element appeared to be restricted to young cotyledons and maturating guard cells. Mutational analyses demonstrated that the co-operation of Oct with another module (Hex, TCA or CCAAT-box) was absolutely required for both temporal and spatial regulation. Thus, OCEs play a pivotal role in regulation of the expression of plant histone genes.

The modular structure and function of the wheat H1 promoter with S phase-specific activity.

Two histone H1 genes, TH315 and TH325, were isolated from a wheat genomic library. Nucleotide sequence analysis and comparison with other histone gene promoters revealed that the promoters of both genes contain many characteristic motifs conserved among plant histone H1 genes. They are 6 novel short stretches, named CS1 to CS6, and already documented elements or their relatives such as Oct, Oct-like (OLS), Nona-like (NonaLS), CCAAT box, and TATA box. Transient expression experiments with the TH315 promoter/GUS chimeric gene and its mutagenized derivatives showed that two Oct motifs, OLS, and CCAAT box are positive cis-acting elements. NonaLS and CS4 were suggested to be positive cis-acting elements and CS5 and CS6 to be negative elements. An Oct motif and CCAAT box constitutes a type III element and the 202-bp sequence containing these elements from -128 to +74 of the TH315 gene was shown to be sufficient to confer S phase-specific expression. The type III element is found in all plant histone H1 and H2B genes, suggesting that it is a subtype-specific element. Most plant histone genes have one of the type I, II, and III elements. We propose to classify the plant histone genes into three classes, based on the context of Oct in the promoters.

FASCIATA genes for chromatin assembly factor-1 in arabidopsis maintain the cellular organization of apical meristems.

Postembryonic development of plants depends on the activity of apical meristems established during embryogenesis. The shoot apical meristem (SAM) and the root apical meristem (RAM) have similar but distinct cellular organization. Arabidopsis FASCIATA1 (FAS1) and FAS2 genes maintain the cellular and functional organization of both SAM and RAM, and FAS gene products are subunits of the Arabidopsis counterpart of chromatin assembly factor-1 (CAF-1). fas mutants are defective in maintenance of the expression states of WUSCHEL (WUS) in SAM and SCARECROW (SCR) in RAM. We suggest that CAF-1 plays a critical role in the organization of SAM and RAM during postembryonic development by facilitating stable maintenance of gene expression states.

Development of grating acuity in infants with Retinopathy of Prematurity.

PURPOSE: To evaluate the visual development in infants with stage 1 approximately 3 ROP and compare their visual results with healthy preterm infants. PATIENTS AND METHODS: One hundred forty-four premature infants were recruited and were divided into 3 groups according to the stage of ROP. Randomly selected preterm subjects with no ROP were taken as controls. Ophthalmic examinations started 4 to 7 weeks after birth and were repeated as needed until the retina was fully vascularized or until any ROP that developed had resolved. Grating acuity was measured by acuity cards between 35-45 weeks of corrected age and by PL method at 12, 18 and 24 months of age. RESULTS: Infants with stage 3 ROP had slightly lower visual acuity scores compared to other infants at most of the testing points throughout the 35-45 week period, which did not show statistical significance at any week. Infants with stage 2 and 3 ROP had similar visual acuity values but slightly lower acuity scores than infants with stage I or no ROP at the 12 month follow-up. The differences were not statistically significant. Stage 3 ROP infants had significantly lower acuity scores compared to infants with stage 1-2 or no ROP at the 18 and 24 month follow-up visits (p<0.0001). CONCLUSION: We stress periodic monitoring of early visual acuity in infants with ROP because of the possibility of impaired visual development.