Corneal thickness and elevation measurements using swept-source optical coherence tomography and slit scanning topography in normal and keratoconic eyes.

BACKGROUND: To compare corneal thickness and corneal elevation using swept source optical coherence tomography and slit scanning topography. DESIGN: Prospective study. PARTICIPANTS: 41 normal and 46 keratoconus subjects. METHODS: All eyes were imaged using swept source optical coherence tomography and slit scanning tomography during the same visit. Mean corneal thickness and best-fit sphere measurements were compared between the instruments. MAIN OUTCOME MEASURES: Agreement of measurements between swept source optical coherence tomography and scanning slit topography was analyzed. Intra-rater reproducibility coefficient and intraclass correlation coefficient were evaluated. RESULTS: In normal eyes, central corneal thickness measured by swept source optical coherence tomography was thinner compared with slit scanning topography (p < 0.0001) and ultrasound pachymetry (p = < .0001). Ultrasound pachymetry readings had better 95% limits of agreement with swept source optical coherence tomography than slit scanning topography. In keratoconus eyes, central corneal thickness was thinner on swept source optical coherence tomography than slit scanning topography (p = 0.081) and ultrasound pachymetry (p = 0.001). There were significant differences between thinnest corneal thickness, and, anterior and posterior best-fit sphere measurements between both instruments (p < 0.05 for all). Overall, reproducibility coefficients and intraclass correlation coefficients were significantly better with swept source optical coherence tomography for measurement of central corneal thickness, anterior best-fit sphere and, posterior best-fit sphere (all p < 0.001). CONCLUSIONS: Corneal thickness and elevation measurements were significantly different between swept source optical coherence tomography and slit scanning topography. With better reproducibility coefficients and intraclass correlation coefficients, swept source optical coherence tomography may provide a reliable alternative for measurement of corneal parameters.

Twelve-year outcomes of bedside laser photocoagulation for severe retinopathy of prematurity.

Purpose: The purpose of this study is to evaluate the 12-year outcomes of bedside laser photocoagulation (LP) for severe retinopathy of prematurity (ROP) under sedation combined with ocular surface anesthesia in neonatal intensive care units (NICU). Design: The study is a retrospective case series. Methods: Infants treated with bedside LP for severe ROP from April 2009 to September 2021 were included. All LP treatments were performed under sedation and surface anesthesia at the bedside in NICU. Data were recorded for clinical and demographic characteristics, total laser spots, duration of treatment, proportion of total regression of ROP, proportion of recurrence, and adverse events. Results: A total of 364 infants (715 eyes) were included, with a mean gestational age of 28.6 ± 2.4 weeks (range: 22.6-36.6 weeks) and a mean birth weight of 1,156.0 ± 339.0 g (range: 480-2,200 g). The mean number of laser spots was 832 ± 469, and the mean duration of treatment was 23.5 ± 5.3 min per eye. Of all the eyes, 98.3% responded to LP with complete regression of ROP. ROP recurred in 15 (2.1%) eyes after the initial LP. Additional LP was performed in seven (1.0%) eyes. No patient exhibited mistaken LP of other ocular tissues, and there were no serious ocular adverse effects. None of them needed endotracheal intubation. Conclusions: Bedside LP treatment is effective and safe for premature infants with severe ROP under sedation and surface anesthesia in NICU, especially for infants whose general condition is unstable and not suitable for transport.

Optic disc imaging with spectral-domain optical coherence tomography: variability and agreement study with Heidelberg retinal tomograph.

OBJECTIVE: To evaluate the agreement of optic disc measurements obtained with the Cirrus high-density optical coherence tomography (HD-OCT) and the Heidelberg retina tomograph (HRT) and compare the intervisit, test-retest variability between the instruments. DESIGN: Prospective, cross-sectional study. PARTICIPANTS: Two hundred seven subjects (109 glaucoma and 98 normal subjects). METHODS: One eye from each individual was selected randomly for optic disc imaging by the Cirrus HD-OCT and the HRT. Areas of the optic disc and the cup, cup volume, vertical cup-to-disc ratio and cup-to-disc area ratio were compared between the instruments. The OCT measurements were corrected for ocular magnification using the Littman's formula. The measurement agreement was evaluated with the Bland-Altman plots. The intervisit test-retest variability was examined in 17 randomly selected glaucoma patients who underwent optic disc imaging weekly for 8 consecutive weeks. The intraclass correlation coefficients (ICC) and the reproducibility coefficients of the optic disc parameters were computed. MAIN OUTCOME MEASURES: Measurement agreement, reproducibility coefficients, and ICCs of optic disc parameters. RESULTS: The OCT measured smaller optic disc and rim areas and greater cup volume, vertical cup-to-disc ratio and cup-to-disc area ratio than the HRT did (all with P<0.001). There were proportional biases in the Bland-Altman plots between OCT and HRT optic disc measurements except for rim area and cup-to-disc area ratio. The 95% limits of agreement of rim area ranged between -0.28 and 0.88 mm(2) before, and between -0.22 and 0.92 mm(2) after correction for ocular magnification. Both OCT and HRT showed high test-retest reproducibility with ICCs ≥ 0.921. Although the reproducibility coefficient of OCT rim area (0.093 mm(2); 95% confidence interval [CI], 0.081-0.105 mm(2)) was significantly smaller than that of the HRT (0.186 mm(2); 95% CI, 0.163-0.210 mm(2); P = .018), there were no differences in the ICCs between the instruments. CONCLUSIONS: Optic disc assessment by spectral-domain OCT and confocal scanning laser ophthalmoscopy demonstrates poor agreement but similarly low test-retest variability. The source of their disagreement and its effects on the detection of progression require further study.

Free sialic acid storage disease without sialuria.

We performed high-resolution in vitro proton nuclear magnetic resonance spectroscopy on cerebrospinal fluid and urine samples of 44 patients with leukodystrophies of unknown cause. Free sialic acid concentration was increased in cerebrospinal fluid of two siblings with mental retardation and mild hypomyelination. By contrast, urinary excretion of free sialic acid in urine was normal on repeated testing by two independent methods. Both patients were homozygous for the K136E mutation in SLC17A5, the gene responsible for the free sialic acid storage diseases. Our findings demonstrate that mutations in the SLC17A5 gene have to be considered in patients with hypomyelination, even in the absence of sialuria.

Efficient gene delivery to pancreatic islets with ultrasonic microbubble destruction technology.

This study describes a method of gene delivery to pancreatic islets of adult, living animals by ultrasound targeted microbubble destruction (UTMD). The technique involves incorporation of plasmids into the phospholipid shell of gas-filled microbubbles, which are then infused into rats and destroyed within the pancreatic microcirculation with ultrasound. Specific delivery of genes to islet beta cells by UTMD was achieved by using a plasmid containing a rat insulin 1 promoter (RIP), and reporter gene expression was regulated appropriately by glucose in animals that received a RIP-luciferase plasmid. To demonstrate biological efficacy, we used UTMD to deliver RIP-human insulin and RIP-hexokinase I plasmids to islets of adult rats. Delivery of the former plasmid resulted in clear increases in circulating human C-peptide and decreased blood glucose levels, whereas delivery of the latter plasmid resulted in a clear increase in hexokinase I protein expression in islets, increased insulin levels in blood, and decreased circulating glucose levels. We conclude that UTMD allows relatively noninvasive delivery of genes to pancreatic islets with an efficiency sufficient to modulate beta cell function in adult animals.

Characterization of the bidirectional promoter region between the human genes encoding VLCAD and PSD-95.

Bidirectional promoters are widely known among lower organisms but rare in mammals. A shared promoter between the two human genes encoding very long chain acyl-CoA dehydrogenase (VLCAD) and postsynaptic density protein 95 (PSD-95) is an ideal model to investigate bidirectional transcription in mammals. VLCAD associates with the inner mitochondrial membrane and catalyzes the initial step in mitochondrial long-chain fatty acid beta-oxidation. PSD-95, a component protein of the PSD, plays an essential role in clustering the transmembrane proteins in synaptic membranes. Interestingly, the human genes encoding VLCAD (ACADVL) and PSD-95 (DLG4) are adjacently located in the head-to-head orientation on chromosome 17p. The transcribed regions of the two genes overlap, while the two transcription start sites stand approximately 220 bp apart. To analyze the common transcriptional control region shared by the two genes, we generated serial promoter partial deletion constructs using firefly luciferase as the reporter gene. Our results showed that the essential promoter activity of PSD-95 is carried within an approximately 400-bp region, which covers the entire approximately 270-bp minimal promoter of VLCAD. The results from di-(2-ethylhexyl) phthalate (DEHP)-treated HepG2 cells revealed that the minimal VLCAD promoter is able to up-regulate VLCAD expression in response to DEHP treatment. Site-directed mutagenesis experiments showed that a mutated activator protein 2-binding site markedly reduced the transcriptional activity of both promoters and abolished the minimal VLCAD promoter's response to DEHP treatment.

T cell receptor transgenic mice recognizing the immunodominant epitope of the Torpedo californica acetylcholine receptor.

Myasthenia gravis (MG) is an autoimmune disease caused by T cell-dependent antibody-mediated reduction of acetylcholine receptors (AChR) at the neuromuscular junction. Immunization of animals with Torpedo californica AChR (TAChR) results in an experimental model of MG. We used the variable regions of alpha and beta T cell receptor (TCR) genes recognizing an immunodominant peptide containing amino acids 146-162 from the alpha subunit of TAChR presented in the context of I-A(b) to generate TCR-transgenic mice. We found that the transgenic TCR was strongly positively selected and that transgenic T cells proliferated robustly to the immunodominant peptide and TAChR. Unexpectedly, there was a variable paucity of B cells in the blood and spleen from transgenic mice, which averaged about 16% of peripheral blood lymphocytes, compared to 55% in wild-type B6 mice. Unselected transgenic mice immunized with TAChR exhibited weak anti-TAChR antibody responses. However, transgenic mice selected to have relatively higher B cell numbers produced anti-TAChR titers equal to B6 mice and a predominance of Th1-induced antibody isotypes were observed in certain experiments. The incidence and severity of clinical disease was variable following immunizations. These mice should be useful for studying the pathogenesis and treatment of MG.