Radiation-induced apoptosis of oligodendrocytes in the adult rat optic chiasm

The role of apoptosis in spinal cord injury: a bibliometric analysis from 1994 to 2023

Background

Apoptosis after spinal cord injury (SCI) plays a pivotal role in the secondary injury mechanisms, which cause the ultimate neurologic insults. A better understanding of the molecular and cellular basis of apoptosis in SCI allows for improved glial and neuronal survival via the administrations of anti-apoptotic biomarkers. The knowledge structure, development trends, and research hotspots of apoptosis and SCI have not yet been systematically investigated.

Methods

Articles and reviews on apoptosis and SCI, published from 1st January 1994 to 1st Oct 2023, were retrieved from the Web of Science™. Bibliometrix in R was used to evaluate annual publications, countries, affiliations, authors, sources, documents, key words, and hot topics.

Results

A total of 3,359 publications in accordance with the criterions were obtained, which exhibited an ascending trend in annual publications. The most productive countries were the USA and China. Journal of Neurotrauma was the most impactive journal; Wenzhou Medical University was the most prolific affiliation; Cuzzocrea S was the most productive and influential author. "Apoptosis," "spinal-cord-injury," "expression," "activation," and "functional recovery" were the most frequent key words. Additionally, "transplantation," "mesenchymal stemness-cells," "therapies," "activation," "regeneration," "repair," "autophagy," "exosomes," "nlrp3 inflammasome," "neuroinflammation," and "knockdown" were the latest emerging key words, which may inform the hottest themes.

Conclusions

Apoptosis after SCI may cause the ultimate neurological damages. Development of novel treatments for secondary SCI mainly depends on a better understanding of apoptosis-related mechanisms in molecular and cellular levels. Such therapeutic interventions involve the application of anti-apoptotic agents, free radical scavengers, as well as anti-inflammatory drugs, which can be targeted to inhibit core events in cellular and molecular injury cascades pathway.

Histopathological evaluation of the effects of dexmedetomidine against pituitary damage ınduced by X-ray irradiation

Background: The present study, aimed to investigate the potential negative effects of x-ray radiation and the effects of the α2-adrenergic receptor agonist dexmedetomidine on the pituitary gland.Methods: Twenty-four Sprague-Dawley rats were divided into three groups: Rats in Group 1 (control group). Group 2 (X-ray irradiation) and group 3 (X-ray irradiation + Dexmedetomidine) were given a total of 10 Gy external beam total body irradiation. Group 3 was given a single intraperitoneal dose of 200 µg/kg dexmedetomidine 30 minutes before RT.Results: In sections obtained from the x-ray irradiation group, we observed many necrotic in adenohypophysis and neurohypophysis. In addition, there were extensive oedematous areas and vascular congestions due to the necrotic cells in both the adenohypophysis and neurohypophysis. In contrast, we observed a reduction in necrotic chromophobic and chromophilic cells in adenohypophyseal tissue and a reduction in necrotic pituicytes in neurohypophyseal tissue in the dexmedetomidine treatment group. In addition, we determined lower caspase-3 and TUNEL expression in the dexmedetomidine treatment group compared with the x-ray irradiation group. Dexmedetomidine reduced x-ray radiation-induced pituitary damage by preventing apoptosis.Conclusions: The present study demonstrated the use of dexmedetomidine in situations related to radiation toxicity and offers the potential for a comprehensive study.

Prediction of radiation necrosis in a rodent model using magnetic resonance imaging apparent transverse relaxation ([Formula: see text])

BACKGROUND AND PURPOSE

Radiation necrosis remains an irreversible long-term side-effect following radiotherapy to the brain. The ability to predict areas that could ultimately develop into necrosis could lead to prevention and management of radiation necrosis.

MATERIALS AND METHODS

Fischer 344 rats were irradiated using two platforms (micro-CT irradiator and x-Rad 225 IGRT) with radiation up to 30 Gy for the micro-CT and 40 Gy for the xRAD-224 to half the brain. Animals were subsequently imaged using a 9.4 T MRI scanner every 2-4 weeks for up to 28 weeks using a 7-echo gradient echo sequence. The apparent transverse relaxation constant ([Formula: see text]) was calculated and retrospectively analyzed.

RESULTS

Animals irradiated with the low-dose rate micro-CT did not exhibit any symptoms or imaging changes associated with RN. Animals irradiated with the xRAD-225 exhibited imaging changes consistent with RN at week 24. Analysis of the [Formula: see text] coefficient within the lesion and hippocampus shows the potential for detection of RN up to 10 weeks prior to morphological changes.

CONCLUSIONS

The ability to predict areas of RN and increases of [Formula: see text] within the hippocampus provides a method for long-term monitoring and prediction of RN.

Perilesional edema in radiation necrosis reflects axonal degeneration

Background

Recently, we characterized a Gamma Knife® radiation necrosis mouse model with various magnetic resonance imaging (MRI) protocols to identify biomarkers useful in differentiation from tumors. Though the irradiation was focal to one hemisphere, a contralateral injury was observed that appeared to be localized in the white matter only. Interestingly, this injury was identifiable in T2-weighted images, apparent diffusion coefficient (ADC), and magnetization transfer ratio (MTR) maps, but not on post-contrast T1-weighted images. This observation of edema independent of vascular changes is akin to the perilesional edema seen in clinical radiation necrosis.

Findings

The pathology underlying the observed white-matter MRI changes was explored by performing immunohistochemistry for healthy axons and myelin. The presence of both healthy axons and myelin was reduced in the contralateral white-matter lesion.

Conclusions

Based on our immunohistochemical findings, the contralateral white-matter injury is most likely due to axonal degeneration.

Radiosurgery as neuromodulation therapy!

Radiosurgery is commonly considered to be effective through a destructive physical mechanism acting on neural tissue. However, the results of modern neurophysiological, radiological, and histological studies are providing a basis on which to question this assumption. There are now multiple pieces of evidence pointing to a nonlesional mechanism of the radiosurgical action. It appears that tissue destruction is absent or minimal and in almost all cases insufficient to explain the clinical effects produced. There is a real possibility that radiosurgery induces changes in the functioning of neural tissue by differential effects on various neuronal populations and remodeling the glial environment, leading to modulation of function while preserving basic processing. Hence, the majority of radiosurgical procedures induce the desired biological effect without histological destruction of tissue. These findings may result in a major paradigm shift in the treatment of functional brain disorders.