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Cells & Development Jun 2021Slit-Robo signaling has been implicated in regulating several steps of retinal ganglion cell axon guidance, with a central role assigned to Slit2. We report here the...
Slit-Robo signaling has been implicated in regulating several steps of retinal ganglion cell axon guidance, with a central role assigned to Slit2. We report here the phenotypical characterization of a CRISPR-Cas9-generated zebrafish null mutant for this gene, along with a detailed analysis of its expression pattern by WM-FISH. All evident defects in the optic axons in slit2-/- mutants were detected outside the retina, coincident with the major sites of expression at the ventral forebrain, around the developing optic nerve and anterior to the optic chiasm/proximal tract. Anterograde axon tracing experiments in zygotic and maternal-zygotic mutants, as well as morphants, showed the occurrence of axon sorting defects, which appeared mild at the optic nerve level, but more severe in the optic chiasm and the proximal tract. A remarkable sorting defect was the usual splitting of one of the optic nerves in two branches that surrounded the contralateral nerve at the chiasm. Although all axons eventually crossed the midline, the retinotopic order appeared lost at the proximal optic tract, to eventually correct distally. Time-lapse analysis demonstrated the sporadic occurrence of axon misrouting at the chiasm level, which could be responsible for the sorting errors. Our results support previous evidence of a channeling role for Slit molecules in retinal ganglion cell axons at the optic nerve, in addition to a function in the segregation of axons coming from each nerve and from different retinal regions at the medio-ventral area of the forebrain.
Topics: Amino Acid Sequence; Animals; Axons; Base Sequence; Cell Differentiation; Gene Expression Regulation, Developmental; Intracellular Signaling Peptides and Proteins; Models, Biological; Mutation; Optic Chiasm; Optic Nerve; Retinal Ganglion Cells; Visual Pathways; Zebrafish; Zebrafish Proteins
PubMed: 33994352
DOI: 10.1016/j.cdev.2021.203677 -
The British Journal of Ophthalmology Mar 1990
Topics: Albinism; Humans; Optic Chiasm
PubMed: 2322506
DOI: 10.1136/bjo.74.3.130 -
Acta Neurobiologiae Experimentalis Sep 2023Studies have shown that vitamin D plays a crucial role in brain development, brain metabolism and neuroprotection. There is little evidence for the neuroprotective...
Studies have shown that vitamin D plays a crucial role in brain development, brain metabolism and neuroprotection. There is little evidence for the neuroprotective effect of 1, 25‑dihydroxyvitamin D3 (1,25‑(OH)2D3) on various brain injury models. The aim of this study was to investigate the neuroprotection effect of 1,25‑(OH)2D3 against hyperoxia‑induced brain injury in premature rats. Sprague‑Dawley rats were exposed to 95% oxygen or room air for 24 h and treated with 1,25‑(OH)2D3 or normal saline for 14 consecutive days. The histopathological changes of optic chiasma tissue were observed by hematoxylin‑eosin staining. Immunohistochemistry, qRT‑PCR, and western blot were performed to detect the expression of integrin‑β1 and yes‑associated protein (YAP) in the organization of the optic chiasm. Histopathological sections of optic chiasma showed visible optic nerve swelling, expanded nerve fiber space, uneven staining, obvious oligodendrocyte proliferation and disordered cell arrangement accompanied by inflammatory cell infiltration and exudation after 7 days and 14 days of hyperoxia exposure. The hyperoxia group treated with 1,25‑(OH)2D3 were showed improvement of brain injury with reduced inflammatory exudation, uniform nerve fiber staining and less obvious oligodendrocyte proliferation. Immunohistochemical staining, qRT‑PCR and western blot indicated that 1,25‑(OH)2D3 treatment upregulated the expression of integrin‑β1 and YAP in the hyperoxia group on day 7. However, the expression of YAP was significantly increased compared with control group and treatment with 1,25‑(OH)2D3 reduced the expression of YAP in the hyperoxic group on day 14. 1,25‑(OH)2D3 may regulate the expression of integrin‑β1 and YAP to alleviate hyperoxia‑induced brain injury in premature rats.
Topics: Rats; Animals; Calcitriol; Neuroprotective Agents; Hyperoxia; Rats, Sprague-Dawley; Vitamin D; Brain Injuries; Integrins
PubMed: 37874188
DOI: 10.55782/ane-2023-2435 -
Folia Morphologica 2020This paper was undertaken to determine the morphometry of pituitary gland diameter, pituitary gland height, intercavernous distance, optic chiasm diameter and optic...
BACKGROUND
This paper was undertaken to determine the morphometry of pituitary gland diameter, pituitary gland height, intercavernous distance, optic chiasm diameter and optic chiasm height in skulls of Turkish population aged between 18 and 60 years.
MATERIALS AND METHODS
It was a retrospective study in which 292 subjects were included 187 females and 105 males, ranging from 18 up to 60 years. Subjects underwent brain magnetic resonance imaging in the Radiology Department. Statistical analysis was performed with SPSS 21.00 programme. ANOVA test, χ2 test, and Pearson correlation analysis were used to determine the relation and significance between measurements and age group. The p < 0.05 value was considered as significant.
RESULTS
The groups were divided into five groups according to age. The overall means and standard deviations of the measurements were: pituitary gland width, 13.09 ± 1.99 mm; pituitary gland height, 4.91 ± 1.10 mm; intercavernous distance, 15.93 ± 3.05 mm; optic chiasm width, 12.82 ± 1.27 mm; and optic chiasm height, 2.80 ± 0.49 mm in females, respectively whereas, the same measurements were 12.96 ± 1.74 mm; 4.79 ± 0.95 mm; 16.08 ± 3.11 mm; 13.13 ± 1.37 mm; 2.86 ± 0.70 mm in males, respectively. Height of the pituitary gland reached a maximum in the age group of 18 to 20 years in both females and males and there was a decrease in the pituitary gland height in the subsequent age groups.
CONCLUSIONS
Knowledge of the variation in the size of pituitary gland, intercavernous distance and optic chiasm is important to evaluate the dimensions of these structures for clinical and pathological processes.
Topics: Adolescent; Adult; Female; Healthy Volunteers; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Optic Chiasm; Pituitary Gland; Sella Turcica; Turkey; Young Adult
PubMed: 31106844
DOI: 10.5603/FM.a2019.0058 -
The Canadian Veterinary Journal = La... Jan 2013
Topics: Animals; Blindness; Dog Diseases; Dogs; Female; Optic Chiasm; Optic Nerve Neoplasms
PubMed: 23814309
DOI: No ID Found -
ENeuro 2020Spike conduction velocity characteristically differs between myelinated and unmyelinated axons. Here we test whether spikes of myelinated and unmyelinated paths differ...
Spike conduction velocity characteristically differs between myelinated and unmyelinated axons. Here we test whether spikes of myelinated and unmyelinated paths differ in other respects by measuring rat retinal ganglion cell (RGC) spike duration in the intraretinal, unmyelinated nerve fiber layer and the extraretinal, myelinated optic nerve and optic chiasm. We find that rapid spike firing and illumination broaden spikes in intraretinal axons but not in extraretinal axons. RGC axons thus initiate spikes intraretinally and normalize spike duration extraretinally. Additionally, we analyze spikes that were recorded in a previous study of rhesus macaque retinogeniculate transmission and find that rapid spike firing does not broaden spikes in optic tract. The spike normalization we find reduces the number of spike properties that can change during RGC light responses. However, this is not because identical spikes fire in all axons. Instead, our recordings show that different subtypes of RGC generate axonal spikes of different durations and that the differences resemble spike duration increases that alter neurotransmitter release from other neurons. Moreover, previous studies have shown that RGC spikes of shorter duration can fire at higher maximum frequencies. These properties should facilitate signal transfer by different mechanisms at RGC synapses onto subcortical target neurons.
Topics: Animals; Axons; Macaca mulatta; Optic Chiasm; Optic Nerve; Rats; Retina; Retinal Ganglion Cells
PubMed: 32086286
DOI: 10.1523/ENEURO.0504-19.2020 -
Quantitative Imaging in Medicine and... Oct 2021The precise pathogenesis of anophthalmia/microphthalmia remains unknown. Prenatal observation of the optic chiasm in fetuses with this malformation would assist in...
BACKGROUND
The precise pathogenesis of anophthalmia/microphthalmia remains unknown. Prenatal observation of the optic chiasm in fetuses with this malformation would assist in understanding the embryonic development of the condition. The present study aimed to establish the normal fetal size ranges of decussation of the optic chiasm, optic nerves, and optic tracts in the axial plane using two-dimensional transabdominal ultrasound throughout gestation and to compare these ranges to the corresponding values in fetuses with anophthalmia/microphthalmia.
METHODS
In total, 310 normal fetuses and 16 fetuses with anophthalmia/microphthalmia were included in this study. The widths of the decussation of the optic chiasm, optic nerves, and optic tracts of normal fetuses at 19-40 weeks' gestation were measured in the axial plane by two-dimensional transabdominal ultrasound. The same widths were retrospectively measured in the axial plane using three-dimensional ultrasound in fetuses with anophthalmia/microphthalmia and compared to the results from the normal fetuses.
RESULTS
The decussation, optic nerves, and optic tracts of 310 normal fetuses were measured. The normal widths of the decussation of the optic chiasm, optic nerves, and optic tracts increased linearly with gestational age. The interobserver and intraobserver reproducibility was excellent for the decussation but relatively low for the optic nerves and optic tracts. The optic nerve width of fetuses with anophthalmia/microphthalmia was significantly smaller than that of normal fetuses (P<0.001), but the widths of the decussation (P=0.061) and optic tracts (P=0.053) were not significantly different between the two groups.
CONCLUSIONS
The normal ranges of the decussation of the optic chiasm, optic nerves, and optic tracts established in this study can provide a quantitative basis for prenatal evaluation of the optic pathway. Fetal anophthalmia/microphthalmia may be associated with optic nerve hypoplasia.
PubMed: 34603993
DOI: 10.21037/qims-21-151 -
The British Journal of Radiology Mar 2020To assess the radiation-induced optic neuropathy (RION) prevalence, following high dose pencil beam scanning proton therapy (PBSPT) to skull base and head and neck (H&N)...
OBJECTIVE
To assess the radiation-induced optic neuropathy (RION) prevalence, following high dose pencil beam scanning proton therapy (PBSPT) to skull base and head and neck (H&N) tumours.
METHODS
Between 1999 and 2014, 216 adult patients, median age 47 years (range, 18-77), were treated with PBS PT for skull base or H&N malignancies, delivering ≥45 Gy to the optic nerve(s) (ON) and/or optic chiasma (OC). The median administered dose to the planning target volume was 74.0 Gy (range, 54.0-77.4). The median follow-up was 5.3 years (range, 0.8-15.9).
RESULTS
RION was observed in 14 (6.5%) patients at a median time of 13.2 months (range, 4.8-42.6) following PBSPT. Most (92.9%) of RION were symptomatic. Most affected patients (11/14; 79%) developed unilateral toxicity. Grade 4, 3, 2 and 1 toxicity was observed in 10, 2, 1 and 1 patients, respectively. On univariate analyses, age (<70 ≥70 years; < 0.0001), hypertension ( = 0.0007) and tumour abutting the optic apparatus ( = 0.012) were associated with RION. OC's V60 Gy was of border line significance ( = 0.06). None of the other evaluated OC-ON dose/volume metrics (Dmax, Dmean, V40-60) were significantly associated with this complication.
CONCLUSION
These data suggest that high-dose PBS PT for skull base and H&N tumours is associated with a low prevalence of RION. Caution should be however exercised when treating elderly/hypertensive patients with tumours abutting the optic apparatus.
ADVANCES IN KNOWLEDGE
This is the first study reporting the risk of developing RION following proton therapy with PBS technique, demonstrating the safety of this treatment.
Topics: Adolescent; Adult; Age Factors; Aged; Analysis of Variance; Head and Neck Neoplasms; Humans; Hypertension; Middle Aged; Optic Chiasm; Optic Nerve; Optic Nerve Diseases; Prevalence; Proton Therapy; Radiation Injuries; Radiotherapy Dosage; Radiotherapy, Adjuvant; Risk Factors; Skull Base Neoplasms; Young Adult
PubMed: 31322969
DOI: 10.1259/bjr.20190028 -
International Journal of Surgery... Apr 2023Predicting the postoperative visual outcome of pituitary adenoma patients is important but remains challenging. This study aimed to identify a novel prognostic predictor...
Preoperative volume of the optic chiasm is an easily obtained predictor for visual recovery of pituitary adenoma patients following endoscopic endonasal transsphenoidal surgery: a cohort study.
BACKGROUND
Predicting the postoperative visual outcome of pituitary adenoma patients is important but remains challenging. This study aimed to identify a novel prognostic predictor which can be automatically obtained from routine MRI using a deep learning approach.
MATERIALS AND METHODS
A total of 220 pituitary adenoma patients were prospectively enrolled and stratified into the recovery and nonrecovery groups according to the visual outcome at 6 months after endoscopic endonasal transsphenoidal surgery. The optic chiasm was manually segmented on preoperative coronal T2WI, and its morphometric parameters were measured, including suprasellar extension distance, chiasmal thickness, and chiasmal volume. Univariate and multivariate analyses were conducted on clinical and morphometric parameters to identify predictors for visual recovery. Additionally, a deep learning model for automated segmentation and volumetric measurement of optic chiasm was developed with nnU-Net architecture and evaluated in a multicenter data set covering 1026 pituitary adenoma patients from four institutions.
RESULTS
Larger preoperative chiasmal volume was significantly associated with better visual outcomes ( P =0.001). Multivariate logistic regression suggested it could be taken as the independent predictor for visual recovery (odds ratio=2.838, P <0.001). The auto-segmentation model represented good performances and generalizability in internal (Dice=0.813) and three independent external test sets (Dice=0.786, 0.818, and 0.808, respectively). Moreover, the model achieved accurate volumetric evaluation of the optic chiasm with an intraclass correlation coefficient of more than 0.83 in both internal and external test sets.
CONCLUSION
The preoperative volume of the optic chiasm could be utilized as the prognostic predictor for visual recovery of pituitary adenoma patients after surgery. Moreover, the proposed deep learning-based model allowed for automated segmentation and volumetric measurement of the optic chiasm on routine MRI.
Topics: Humans; Optic Chiasm; Pituitary Neoplasms; Cohort Studies; Endoscopy; Prognosis; Adenoma
PubMed: 36999782
DOI: 10.1097/JS9.0000000000000357 -
Frontiers in Veterinary Science 2020Canine optic neuritis has been attributed to a focal or disseminated form of granulomatous meningoencephalitis (GME) amongst other etiologies. Magnetic resonance imaging...
Canine optic neuritis has been attributed to a focal or disseminated form of granulomatous meningoencephalitis (GME) amongst other etiologies. Magnetic resonance imaging (MRI) has been proven to help differentiate the structures within the optic nerve sheath and therefore could aid the diagnosis of optic neuritis in dogs. The objectives of this study were to describe and compare the MRI abnormalities affecting the optic nerve sheath complex and optic chiasm in dogs with clinically suspected optic neuritis as a component of meningoencephalitis of unknown etiology (MUE) or as an isolated form (I-ON). Retrospective evaluation of patient details, clinical signs, cerebrospinal fluid (CSF) analysis, and MRI findings of dogs with clinically suspected optic neuritis between January 2011 and May 2018 was performed. Eighteen dogs met the inclusion criteria. MRI findings included contrast enhancement of both optic nerves (11/18) and optic chiasm (6/18), changes within the CSF volume surrounding the optic nerve (10/18), changes to the optic disc (10/18), changes of size or signal affecting the optic chiasm (10/18), changes in the Short TI inversion recovery (STIR) signal of the optic nerve (7/15), retrobulbar changes (3/18), and concurrent brain lesions (13/18). A variety of subtle MRI features may indicate optic nerve involvement and low-field MRI is a sensitive method to detect changes within the optic nerve sheath complex in dogs with optic neuritis as an isolated form (I-ON) or as an extension of MUE.
PubMed: 33490127
DOI: 10.3389/fvets.2020.585828