•A novel biosensor based on the direct electron transfer of ChOx immobilized on CS–GR was designed.•The preparation process of the biosensor was simple and low cost.•GO was synthesized by a novel ...microwave method and CS–GR was prepared by simple situ reduction of CS–GO.•It exhibited low kmapp, low detection limit, wide linear range and excellent reproducibility and stability.•It exhibited very high specificity to cholesterol with complete elimination of interference from UA, AA, DA and glucose.
A novel cholesterol biosensor (ChOx/CS–GR/GCE) with enhanced sensitivity and low detection limit was investigated. The biosensor based on direct electrochemistry of cholesterol oxidase with an apparent rate constant (ks) of 2.69s−1 was fabricated by immobilizing cholesterol oxidase (ChOx) on Glassy carbon electrode (GCE) functionalized by chitosan–graphene (CS–GR) nanocomposites. Graphene oxide (GO) was synthesized by a novel microwave method and CS–GR was prepared by simple situ reduction of chitosan–graphene oxide (CS–GO). The results of transmission electron microscopy (TEM) and FT-IR spectroscopy showed that the graphene oxide (GO) was successfully prepared and deoxygenized. The presence of the CS–GR nanocomposites not only accelerated direct electron transfer from the enzyme to the electrode surface, but also enhanced the immobilized amount and stability of cholesterol oxidase (ChOx). The fabricated electrode exhibited a linear response to cholesterol in the range of 0.005–1.0mM with a detection limit of 0.715μM (S/N=3). The Michaelis–Menten constant (kmapp) was found as 17.39μM. In addition, the biosensor also exhibited excellent reproducibility, stability and very high specificity to cholesterol with complete elimination of interference from UA, AA, DA and glucose.
Perinatal asphyxia induces neuronal cell death and brain injury, and is often associated with irreversible neurological deficits in children. There is an urgent need to elucidate the neuronal death ...mechanisms occurring after neonatal hypoxia-ischemia (HI). We here investigated the selective neuronal deletion of the Atg7 (autophagy related 7) gene on neuronal cell death and brain injury in a mouse model of severe neonatal hypoxia-ischemia. Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death. Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells. These findings reveal that selective neuronal deletion of Atg7 is strongly protective against neuronal death and overall brain injury occurring after HI and suggest that inhibition of HI-enhanced autophagy should be considered as a potential therapeutic target for the treatment of human newborns developing severe hypoxic-ischemic encephalopathy.
Background
In the past decade, the Chinese drug regulatory system has undergone many changes. A major reform starting in 2015 has significantly reshaped the regulatory processes. It was important to ...assess the impact of the reform on new drug approvals in China.
Method
We analyzed the temporal trends of regulatory characteristics of the new drugs approved by the Chinese regulatory agency from 2011 to 2021, using data collected in the Pharmcube database.
Results
A total of 353 new drugs were approved, including 220 small molecule drugs, 86 biological products and 47 vaccines. The annual number of new drug approvals increased dramatically since 2017, reaching a record high of 70 in 2021. The median NDA approval time was 15.4 months in 2017-2021, the shortest in the decade, and was significantly shorter than that in the pre-reform period. The newly instituted expedited pathways such as priority review (PR) and accelerated approval for urgently needed overseas drugs (UNOD) significantly reduced new drug application (NDA) approval times compared with standard review. For imported drugs, in 2017-2021, the median time difference between the first approval in the world and the approval in China was 5 years, representing significant “drug lag”. However, the proportion of the imported drugs approved in China within 3 years of its first foreign approval has increased to 24.4% in 2017-2021.
Conclusion
The regulatory reform has produced significant, positive immediate outcomes in several metrics of drug regulatory approval. China’s regulatory system will continue to evolve as there still are many areas requiring further reform and improvement.
Posterior fossa tumors are the most common childhood intracranial tumors, and radiotherapy is one of the most effective treatments. However, irradiation induces long-term adverse effects that can ...have significant negative impacts on the patient's quality of life. The purpose of this study was to characterize irradiation-induced cellular and molecular changes in the cerebellum. We found that irradiation-induced cell death occurred mainly in the external germinal layer (EGL) of the juvenile rat cerebellum. The number of proliferating cells in the EGL decreased, and 82.9% of them died within 24 h after irradiation. Furthermore, irradiation induced oxidative stress, microglia accumulation, and inflammation in the cerebellum. Interestingly, blood-brain barrier damage and blood flow reduction was considerably more pronounced in the cerebellum compared to other brain regions. The cerebellar volume decreased by 39% and the migration of proliferating cells to the internal granule layer decreased by 87.5% at 16 weeks after irradiation. In the light of recent studies demonstrating that the cerebellum is important not only for motor functions, but also for cognition, and since treatment of posterior fossa tumors in children typically results in debilitating cognitive deficits, this differential susceptibility of the cerebellum to irradiation should be taken into consideration for future protective strategies.
We have previously shown that lithium treatment immediately after hypoxia-ischemia (HI) in neonatal rats affords both short- and long-term neuroprotection. The aim of this study was to evaluate ...possible therapeutic benefits when lithium treatment was delayed 5 days, a time point when most cell death is over.
Eight-day-old male rats were subjected to unilateral HI and 2 mmol/kg lithium chloride was injected intraperitoneally 5 days after the insult. Additional lithium injections of 1 mmol/kg were administered at 24 h intervals for the next 14 days. Brain injury was evaluated 12 weeks after HI. Serum cytokine measurements and behavioral analysis were performed before sacrificing the animals.
Brain injury, as indicated by tissue loss, was reduced by 38.7%, from 276.5±27.4 mm3 in the vehicle-treated group to 169.3±25.9 mm3 in the lithium-treated group 12 weeks after HI (p<0.01). Motor hyperactivity and anxiety-like behavior after HI were normalized by lithium treatment. Lithium treatment increased neurogenesis in the dentate gyrus as indicated by doublecortin labeling. Serum cytokine levels, including IL-1α, IL-1β, and IL-6, were still elevated as late as 5 weeks after HI, but lithium treatment normalized these cytokine levels.
Delayed lithium treatment conferred long-term neuroprotection in neonatal rats after HI, and this opens a new avenue for future development of treatment strategies for neonatal brain injury that can be administered after the acute injury phase.
Apoptosis inducing factor (AIF) has been shown to be a major contributor to neuron loss in the immature brain after hypoxia-ischemia (HI). Indeed, mice bearing a hypomorphic mutation causing reduced ...AIF expression are protected against neonatal HI. To further investigate the possible molecular mechanisms of this neuroprotection, we generated an AIF knock-in mouse by introduction of a latent transgene coding for flagged AIF protein into the Rosa26 locus, followed by its conditional activation by a ubiquitously expressed Cre recombinase. Such AIF transgenic mice overexpress the pro-apoptotic splice variant of AIF (AIF1) at both the mRNA (5.9 times higher) and protein level (2.4 times higher), but not the brain-specific AIF splice-isoform (AIF2). Excessive AIF did not have any apparent effects on the phenotype or physiological functions of the mice. However, brain injury (both gray and white matter) after neonatal HI was exacerbated in mice overexpressing AIF, coupled to enhanced translocation of mitochondrial AIF to the nucleus as well as enhanced caspase-3 activation in some brain regions, as indicated by immunohistochemistry. Altogether, these findings corroborate earlier studies demonstrating that AIF plays a causal role in neonatal HI brain injury.
Neural stem and progenitor cell (NSPC) transplants provide neuroprotection in models of acute brain injury, but the underlying mechanisms are not fully understood. Here, we provide evidence that ...caspase-dependent apoptotic cell death of NSPCs is required for sending survival signals to the injured brain. The secretome of dying NSPCs contains heat-stable proteins, which protect neurons against glutamate-induced toxicity and trophic factor withdrawal in vitro, and from ischemic brain damage in vivo. Our findings support a new concept suggesting a bystander effect of apoptotic NSPCs, which actively promote neuronal survival through the release of a protective "farewell" secretome. Similar protective effects by the secretome of apoptotic NSPC were also confirmed in human neural progenitor cells and neural stem cells but not in mouse embryonic fibroblasts (MEF) or human dopaminergic neurons, suggesting that the observed effects are cell type specific and exist for neural progenitor/stem cells across species.
PDF
