Cranial irradiation impairs intrinsic excitability and synaptic plasticity of hippocampal CA1 pyramidal neurons with implications for cognitive function

Radiation therapy is a standard treatment for head and neck tumors.However,patients often exhibit cognitive impairments following radiation therapy.Previous studies have revealed that hippocampal dysfunction,specifically abnormal hippocampal neurogenesis or neuroinflammation,plays a key role in radiation-induced cognitive impairment.However,the long-term effects of radiation with respect to the electrophysiological adaptation of hippocampal neurons remain poorly characterized.We found that mice exhibited cognitive impairment 3 months after undergoing 10 minutes of cranial irradiation at a dose rate of 3 Gy/min.Furthermore,we observed a remarkable reduction in spike firing and excitatory synaptic input,as well as greatly enhanced inhibitory inputs,in hippocampal CA1 pyramidal neurons.Corresponding to the electrophysiological adaptation,we found reduced expression of synaptic plasticity marker VGLUT1 and increased expression of VGAT.Furthermore,in irradiated mice,long-term potentiation in the hippocampus was weakened and GluR1 expression was inhibited.These findings suggest that radiation can impair intrinsic excitability and synaptic plasticity in hippocampal CA1 pyramidal neurons.

Serum uric acid is a risk factor for large-artery atherosclerosis cerebral infarction

Using the Trial of Org 10172 in Acute Stroke Treatment （TOAST） classification for acute ischemic stroke, 371 patients with either acute large-artery atherosclerosis or small-artery oc-clusion cerebral infarction were recruited to investigate the potential impact of elevated serum uric acid on cerebrovascular disorders. The results showed that patients who have suffered from large-artery atherosclerosis, relative to small-artery occlusion patients, were characterized by elevated serum uric acid but reduced high-density lipoprotein cholesterol and triglyceride levels. Logistic regression showed that elevated uric acid and lower triglyceride levels were the main risk factors for patients with large-artery atherosclerosis. The findings of this study suggest that hyperuricemia may be a risk factor for stroke.

Brilliant blue G attenuates lipopolysaccharide-mediated microglial activation and inflammation

Previous studies have confirmed that oxidized adenosine triphosphate, a P2X7 receptor antagonist, attenuates lipopolysaccharide-mediated microglial activation and inflammatory expression following neuronal damage in rat brain. NaCI and temperature may affect the potency of oxidized adenosine triphosphate. Brilliant blue G is a derivative of a widely used food additive and has little toxicity. This study explored the effects of brilliant blue G, a selective P2X7 receptor antagonist, on microglial activation and inflammation. Results demonstrated that brilliant blue G inhibited the release of cydooxygenase-2 and interleukin-6 in BV2 cells. Immunofluorescence displayed that brilliant blue G could suppress lipopolysaccharide-induced microglial activation. This study used RNA interference to block P2X7 receptor expression and found that small interfering RNA also suppressed the release of cyclooxygenase-2 and interleukin-6 in BV2 cells. These results suggested that downregulation of the P2X7 receptor by brilliant blue G was involved in the inhibition of microglial activation and inflammation.

Digit and letter alexia in carbon monoxide poisoning

This study examined a 24-year-old patient with delayed encephalopathy, who was admitted to hospital with complaints of headache and visual impairment 1 week after acute carbon monoxide poisoning. The results of a visual field assessment, electroencephalography and head magnetic resonance imaging indicated damage to the cerebral cortex. After a 2-week treatment period, the patient had recovered from the visual impairment, but exhibited digit- and letter-reading difficulty. The Chinese aphasia battery and the number and letter battery supplement were conducted. The results revealed that the patient exhibited digit and letter alexia, while the ability to read Chinese characters was preserved. In contrast, the patient exhibited a deficit in Chinese character writing, while number and letter writing remained intact. Following treatment, reading and writing ability was improved and electroencephalographic abnormalities were ameliorated. Overall, our experimental findings demonstrated that delayed encephalopathy following acute carbon monoxide poisoning was characterized by digit and letter alexia.

Structure of the brachial plexus root and adjacent regions displayed by ultrasound imaging

Brachial plexuses of 110 healthy volunteers were examined using high resolution color Doppler ultrasound. Ultrasonic characteristics and anatomic variation in the intervertebral foramen, interscalene, supraclavicular and infraclavicular, as well as the axillary brachial plexus were investigated. Results confirmed that the normal brachial plexus on cross section exhibited round or elliptic hypoechoic texture. Longitudinal section imaging showed many parallel linear hypo-moderate echoes, with hypo-echo. The transverse processes of the seventh cervical vertebra, the scalene space, the subclavian artery and the deep cervical artery are important markers in an examination. The display rates for the interscalene, and supraclavicular and axillary brachial plexuses were 100% each, while that for the infraclavicular brachial plexus was 97%. The region where the normal brachial plexus root traversed the intervertebral foramen exhibited a regular hypo-echo. The display rate for the C5-7 nerve roots was 100%, while those for C8 and T1 were 83% and 68%, respectively. A total of 20 of the 110 subjects underwent cervical CT scan. High-frequency ultrasound can clearly display the outline of the transverse processes of the vertebrae, which were consistent with CT results. These results indicate that high-frequency ultrasound provides a new method for observing the morphology of the brachial plexus. The C~ vertebra is a marker for identifying the position of brachial plexus nerve roots.

Renovascular hypertension causes cerebral vascular remodeling

Renovascular hypertensive rats （RHRs） were developed using the 2-kidney, 2-clip method. All RHRs at 10 weeks displayed high permeability of the cerebral surface blood vessels. Vascular casts of the RHRs showed that the vascular network was sparse. The arterioles of the RHRs at 10 weeks had smaller lumen diameters, but thicker vessel walls with hyalinosis formation compared with control animals. The endothelial cell membrane appeared damaged, and microthrombus formed. After ischemia, the infarction size was larger in RHRs than in control animals. These results suggest that cerebral arterioles in RHRs underwent structural remodeling. High blood pressure may aggravate the severity of brain injury in cerebral ischemia and affect the recovery of ischemia.

New Insights into the Dysfunctions of Pericytes and Neurovascular Units in Neurodegenerative Diseases

The neurovascular unit(NVU)is an essential anatomical and physiological entity for the maintenance of brain homeostasis and function;it is composed of endothelial cells,pericytes,astrocytes,neurons,vascular smooth muscle cells,microglia,and oligodendroglia[1].The NVU regulates important brain vessel properties such as the integrity of the blood-brain barrier(BBB)and cerebral blood flow(CBF).Considerable efforts have been made to investigate the cerebral microcirculatory dysfunction in ageing and Alzheimer’s disease(AD)[2].

Risk factors and causes of hyponatremia in patients after radiotherapy for head and neck cancer:A retrospective study

Background:Hyponatremia is the most frequently encountered electrolyte abnormality which is caused by kinds of reasons including kidney,metabolic and central nervous system diseases.The adverse effects of hyponatremia include but not limit to cerebral edema and seizures,which often aggravate neurological damage.Therefore,early diagnosis and intervention would reduce the risk of adverse effects of hyponatremia.Objective:To investigate the differences between patients with or without hyponatremia after radiotherapy for head and neck cancer,and to explore the risk factors and causes of hyponatremia.Methods:Patients who aged over 18 years old and underwent radiotherapy for head and neck cancer were collected from Department of Neurology,Sun Yat-Sen Memorial Hospital from January 2012 to July 2018.The comorbidities of patients and demographic and serological data were retrospectively collected to investigate the causes and risk factors of hyponatremia in these patients.Differences of the length of hospital stay and the cognitive function between patients with and without hyponatremia were analyzed.Results:In this study,798 patients were reviewed.The incidence of hyponatremia was 17.9%.Risk factors of hyponatremia included age(OR 1.05,95%CI 1.03–1.07,P<0.001),gender(OR 0.62,95%CI 0.39–0.99,P=0.046),medical history of hypothyroidism(OR 2.42,95%CI 1.26–4.09,P紏0.006),adrenal insufficiency(OR 15.61,95%CI 2.73–89.07,P=0.002)or dysphagia(OR 1.81,95%CI 1.24–2.65,P=0.002).The most common cause of hyponatremia was cerebral salt-wasting syndrome(CSWS)(32.9%).The insufficient intake due to dysphagia(29.4%),and hypothyroidism(13.3%)were also common in these patients.Clinically,hyponatremia resulted in the prolonged hospitalization time.Conclusion:Hyponatremia would be common in patients who underwent radiotherapy for head and neck cancer.The importance of distinguishing the etiology of hyponatremia is addressed.