ABSTRACT
The overproduction of neurotoxic amyloid-ß (Aß) peptides in the brain is a hallmark of Alzheimer's disease (AD). To determine the role of intracellular zinc ion (iZn2+) dysregulation in mediating Aß-related neurotoxicity, this study aimed to investigate whether N, N, N', N'tetrakis (2pyridylmethyl) ethylenediamine (TPEN), a Zn2+specific chelator, could attenuate Aß25-35induced neurotoxicity and the underlying mechanism. We used the 3-(4, 5-dimethyl-thiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay to measure the viability of primary hippocampal neurons. We also determined intracellular Zn2+ and Ca2+ concentrations, mitochondrial and lysosomal functions, and intracellular reactive oxygen species (ROS) content in hippocampal neurons using live-cell confocal imaging. We detected L-type voltage-gated calcium channel currents (L-ICa) in hippocampal neurons using the wholecell patchclamp technique. Furthermore, we measured the mRNA expression levels of proteins related to the iZn2+ buffer system (ZnT-3, MT-3) and voltage-gated calcium channels (Cav1.2, Cav1.3) in hippocampal neurons using RT-PCR. The results showed that TPEN attenuated Aß25-35induced neuronal death, relieved the Aß25-35induced increase in intracellular Zn2+ and Ca2+ concentrations; reversed the Aß25-35induced increase in ROS content, the Aß25-35induced increase in the L-ICa peak amplitude at different membrane potentials, the Aß25-35induced the dysfunction of the mitochondria and lysosomes, and the Aß25-35induced decrease in ZnT-3 and MT-3 mRNA expressions; and increased the Cav1.2 mRNA expression in the hippocampal neurons. These results suggest that TPEN, the Zn2+-specific chelator, attenuated Aß25-35induced neuronal damage, correlating with the recovery of intracellular Zn2+ and modulation of abnormal Ca2+-related signaling pathways.
Subject(s)
Amyloid beta-Peptides , Neurons , Reactive Oxygen Species/metabolism , Amyloid beta-Peptides/toxicity , Amyloid beta-Peptides/metabolism , Neurons/metabolism , Zinc/pharmacology , Zinc/metabolism , Chelating Agents , RNA, Messenger/metabolism , Peptide Fragments/toxicity , Peptide Fragments/metabolism , ApoptosisABSTRACT
OBJECTIVES: To study the efficiency of electrocardiogram (ECG) monitor for positioning the catheter tip in the placement of peripherally inserted central venous catheterization (PICC) via lower extremity veins in neonates. METHODS: A total of 120 neonates who were admitted to the neonatal intensive care unit from January 2020 to January 2022 and received PICC via lower extremity veins were enrolled and divided into a control group and an observation group using a random number table (n=60 each). The neonates in the control group were given body surface measurement and postoperative chest X-ray localization, and those in the observation group were given body surface measurement, ECG-guided positioning, and postoperative chest X-ray localization. The two groups were compared in terms of general information, one-time success rate of PICC placement, and time spent on PICC placement, and the efficiency of ECG-guided positioning was evaluated. RESULTS: Compared with the control group, the observation group had a higher one-time success rate of PICC placement (92% vs 75%; P<0.05) and a shorter time spent on PICC placement [(26.5±3.0) min vs (31.8±2.8) min; P<0.05]. ECG-guided positioning had a sensitivity of 90.9% and a specificity of 100% in the PICC placement via lower extremity veins in neonates. CONCLUSIONS: ECG monitor helps to determine the position of catheter tip in the PICC placement via lower extremity veins in neonates and can improve the one-time success rate of PICC placement and reduce the time spent on PICC placement, with a good positioning efficiency.
Subject(s)
Catheterization, Central Venous , Catheterization, Peripheral , Central Venous Catheters , Infant, Newborn , Humans , Electrocardiography , Lower Extremity , CathetersABSTRACT
To understand the role of intracellular zinc ion (Zn2+) dysregulation in mediating age-related neurodegenerative changes, particularly neurotoxicity resulting from the generation of excessive neurotoxic amyloid-ß (Aß) peptides, this study aimed to investigate whether N, N, N', N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), a Zn2+-specific chelator, could attenuate Aß25-35-induced neurotoxicity and the underlying electrophysiological mechanism. We used the 3-(4, 5-dimethyl-thiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay to measure the viability of hippocampal neurons and performed single-cell confocal imaging to detect the concentration of Zn2+ in these neurons. Furthermore, we used the whole-cell patch-clamp technique to detect the evoked repetitive action potential (APs), the voltage-gated sodium and potassium (K+) channels of primary hippocampal neurons. The analysis showed that TPEN attenuated Aß25-35-induced neuronal death, reversed the Aß25-35-induced increase in intracellular Zn2+ concentration and the frequency of APs, inhibited the increase in the maximum current density of voltage-activated sodium channel currents induced by Aß25-35, relieved the Aß25-35-induced decrease in the peak amplitude of transient outward K+ currents (IA) and outward-delayed rectifier K+ currents (IDR) at different membrane potentials, and suppressed the steady-state activation and inactivation curves of IA shifted toward the hyperpolarization direction caused by Aß25-35. These results suggest that Aß25-35-induced neuronal damage correlated with Zn2+ dysregulation mediated the electrophysiological changes in the voltage-gated sodium and K+ channels. Moreover, Zn2+-specific chelator-TPEN attenuated Aß25-35-induced neuronal damage by recovering the intracellular Zn2+ concentration.
Subject(s)
Amyloid beta-Peptides/toxicity , Ethylenediamines/pharmacology , Nerve Tissue Proteins/physiology , Neurons/drug effects , Peptide Fragments/toxicity , Potassium Channels, Voltage-Gated/physiology , Voltage-Gated Sodium Channels/physiology , Zinc/physiology , Action Potentials/drug effects , Animals , Cells, Cultured , Female , Hippocampus/cytology , Ion Channel Gating/drug effects , Male , Neurons/physiology , Patch-Clamp Techniques , Rats , Single-Cell AnalysisABSTRACT
AIM: To investigate the efficacy of glycyrrhizin (GL) combined with salbutamol (SA) as an anti-asthma therapy. METHODS: Rat lung beta2-adrenergic receptor (beta(2)-AR) mRNA level was measured by real-time RT PCR. Intracellular cAMP accumulation was evaluated with a reporter gene assay. An in vitro acetylcholine-induced guinea pig tracheal strip contraction model was used to test the relaxing effects of GL and SA. The anti-inflammatory effects of GL and SA were tested using tumor necrosis factor-alpha-induced NF-kappaB transcriptional activation reporter assay, I-kappaB Western blotting and interleukin-8 ELISA. An in vivo guinea pig asthma model was used to prove further the synergistic effect of GL and SA. RESULTS: GL (0.3 micromol/L) increased mRNA levels of beta(2)-AR in vivo and the accumulation of cAMP in vitro. The combination of GL and SA also resulted in significant complementary anti-inflammatory effects via inhibition of NF-kappaB activation, degradation of I-kappaB and production of interleukin-8. A significant synergistic effect of the combination was detected both in vitro and in vivo in a guinea pig mode. CONCLUSION: The results demonstrate that GL and SA have synergistic anti-asthmatic effects and offer the possibility of a therapeutic application of GL in combination with beta(2)-AR agonists in the treatment of asthma.
