Point Analysis in Java applied to histological images of the perforant pathway: a user's account

Corneal Structural Changes in Congenital Glaucoma

OBJECTIVE

To identify corneal structure differences on quantitative high-frequency ultrasound biomicroscopy (UBM) among subjects with congenital glaucoma compared with controls.

METHODS

This prospective case-control study evaluated 180 UBM images from 44 eyes of 30 subjects (18 control and 12 glaucoma, mean age 5.2±8.0 years, range 0.2-25.8 years) enrolled in the Pediatric Anterior Segment Imaging and Innovation Study (PASIIS). ImageJ was used to quantify a comprehensive set of corneal structures according to 21 quantitative parameters. Statistical analysis compared corneal measurements in glaucoma subtypes and age-matched controls with significance testing and mixed effects models.

RESULTS

Significant differences between congenital glaucoma cases and controls were identified in 16 of 21 measured parameters including angle-to-angle, central and peripheral corneal thicknesses, scleral integrated pixel density, anterior corneal radius of curvature, and posterior corneal radius of curvature. Eight parameters differed significantly between primary congenital glaucoma and glaucoma following congenital cataract surgery.

CONCLUSION

Multiple measurable corneal structural differences exist between congenital glaucoma and control eyes, and between primary and secondary congenital glaucoma, including but not limited to corneal width and thickness. The structural differences can be quantified from UBM image analysis. Further studies are needed to determine whether corneal features associated with glaucoma can be used to diagnose or monitor progression of congenital glaucoma.

Pediatric Corneal Structural Development During Childhood Characterized by Ultrasound Biomicroscopy

PURPOSE

To quantitatively describe the structural corneal changes from infancy to early adulthood using ultrasound biomicroscopy.

METHODS

In this prospective study, 168 ultrasound biomicroscopy images were obtained from 24 healthy eyes of 24 patients who consented and enrolled in the Pediatric Anterior Segment Imaging Innovation Study. Their ages ranged from birth to 26 years. An established ultrasound biomicroscopy imaging protocol including seven views of one eye per patient were obtained and measured using ImageJ software (National Institutes of Health). Twelve corneal structural parameters were measured. Means were compared between younger and older groups.

RESULTS

Among the 12 measured structures, 5 demonstrated statistically significant differences (P < .05) between patients younger than 1 year and patients older than 1 year. The mean values for corneal cross-sectional width and length, central corneal thickness, and radii of curvature (anterior and posterior) were significantly different in patients younger than 1 year. Curvature and limbus-to-limbus dimensions changed more dramatically than thickness and tissue density. When comparing the youngest to oldest subgroups, anterior curvature flattened (6.14 to 7.55 radius), posterior curvature flattened (5.53 to 6.72 radius), angle-to-angle distance increased (8.93 to 11.40 mm), and endothelial cross-sectional distance increased (10.63 to 13.61 mm).

CONCLUSIONS

Pediatric corneal structures change with age. The most significant changes occur in the first months of life, with additional changes later in childhood. This study further demonstrates the importance of age in pediatric corneal imaging analysis. [J Pediatr Ophthalmol Strabismus. 2020;57(4):238-245.].

Localization and pharmacological modulation of GABA-B receptors in the globus pallidus of parkinsonian monkeys

Changes in GABAergic transmission in the external and internal segments of the globus pallidus (GPe and GPi) contribute to the pathophysiology of the basal ganglia network in Parkinson's disease. Because GABA-B receptors are involved in the modulation of GABAergic transmission in GPe and GPi, it is possible that changes in the functions or localization of these receptors contribute to the changes in GABAergic transmission. To further examine this question, we investigated the anatomical localization of GABA-B receptors and the electrophysiologic effects of microinjections of GABA-B receptor ligands in GPe and GPi of MPTP-treated (parkinsonian) monkeys. We found that the pattern of cellular and ultrastructural localization of the GABA-BR1 subunit of the GABA-B receptor in GPe and GPi was not significantly altered in parkinsonian monkeys. However, the magnitude of reduction in firing rate of GPe and GPi neurons produced by microinjections of the GABA-B receptor agonist baclofen was larger in MPTP-treated animals than in normal monkeys. Injections of the GABA-B receptor antagonist CGP55845A were more effective in reducing the firing rate of GPi neurons in parkinsonian monkeys than in normal animals. In addition, the injections of baclofen in GPe and GPi, or of CGP55845A in GPi lead to a significant increase in the proportion of spikes in rebound bursts in parkinsonian animals, but not in normal monkeys. Thus, despite the lack of changes in the localization of GABA-BR1 subunits in the pallidum, GABA-B receptor-mediated effects are altered in the GPe and GPi of parkinsonian monkeys. These changes in GABA-B receptor function may contribute to bursting activities in the parkinsonian state.

Localization and function of GABA transporters in the globus pallidus of parkinsonian monkeys

The GABA transporters GAT-1 and GAT-3 are abundant in the external and internal segments of the globus pallidus (GPe and GPi, respectively). We have shown that pharmacological blockade of either of these transporters results in decreased neuronal firing, and in elevated levels of extracellular GABA in normal monkeys. We now studied whether the electrophysiologic and biochemical effects of local intra-pallidal injections of GAT-1 and GAT-3 blockers, or the subcellular localization of these transporters, are altered in monkeys rendered parkinsonian by the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The subcellular localization of the transporters in GPe and GPi, studied with electron microscopy immunoperoxidase, was similar to that found in normal animals: i.e., GAT-3 immunoreactivity was mostly confined to glial processes, while GAT-1 labeling was expressed in unmyelinated axons and glial processes. A combined injection/recording device was used to record the extracellular activity of single neurons in GPe and GPi, before, during and after administration of small volumes (1microl) of either the GAT-1 inhibitor, SKF-89976A hydrochloride (720ng), or the GAT-3 inhibitor, (S)-SNAP-5114 (500ng). In GPe, the effects of GAT-1 or GAT-3 blockade were similar to those seen in normal monkeys. However, unlike the findings in the normal state, the firing of most neurons was not affected by blockade of either transporter in GPi. These results suggest that, after dopaminergic depletion, the functions of GABA transporters are altered in GPi; without major changes in their subcellular localization.