Additive Protective Effects of Delayed Mild Therapeutic Hypothermia and Antioxidants on PC12 Cells Exposed to Oxidative Stress

Pan-caspase inhibitor protects against noise-induced hearing loss in a rodent model

Background

Despite the high prevalence of noise-induced hearing loss (NIHL), no effective treatments exist currently. Underlying mechanisms behind NIHL include elevated reactive oxygen species and inflammation, all which ultimately lead to cellular apoptosis. Z-VAD-FMK, an apoptosis inhibitor, has demonstrated protective effects against cochlear hair cells exposed to ototoxic agents; however, its potential for treating NIHL remains unexplored. This study assessed the efficacy of Z-VAD-FMK as a therapeutic for noise-induced cochlear injury in a rodent model.

Methods

Rodents were assigned to one of four groups: (1) unexposed, (2) noise-exposed, (3) noise + vehicle, and (4) noise + Z-VAD-FMK. Noise delivery consisted of 1 h of 110 dB continuous white-noise, with Z-VAD-FMK administered intraperitoneally 6 h afterward. Auditory brainstem responses (ABRs), cochlear hair cell density, and protein levels were evaluated post-interventions.

Results

Noise exposure caused a permanent threshold shift across all frequencies, with minimal recovery by day 28. However, post-exposure treatment with Z-VAD-FMK significantly mitigated ABR threshold, amplitudes, and latencies shifts particularly at low and mid frequencies. Treatment rescued outer hair cells across middle and basal cochlear turns and reduced caspase-9 and IL-1β levels, as indicated by protein analysis.

Conclusion

Our findings indicate that a single intraperitoneal injection of Z-VAD-FMK can partially mitigate cochlear dysfunction induced by acoustic overexposure in a rodent model, highlighting its potential as a therapeutic intervention for NIHL.

Optimal Timing of Targeted Temperature Management for Post-Cardiac Arrest Syndrome: Is Sooner Better?

Targeted temperature management (TTM) is often considered to improve post-cardiac arrest patients’ outcomes. However, the optimal timing to initiate cooling remained uncertain. This retrospective analysis enrolled all non-traumatic post-cardiac arrest adult patients with either out-of-hospital cardiac arrest (OHCA) or in-hospital cardiac arrest (IHCA) who received TTM from July 2015 to July 2021 at our hospital. The values of time delay before TTM and time to target temperature were divided into three periods according to optimal cut-off values identified using receiver operating characteristic curve analysis. A total of 177 patients were enrolled. A shorter time delay before TTM (pre-induction time) was associated with a lower survival chance at 28 days (32.00% vs. 54.00%, p = 0.0279). Patients with a longer cooling induction time (>440 minis) had better neurological outcomes (1.58% vs. 1.05%; p = 0.001) and survival at 28 days (58.06% vs. 29.25%; p = 0.006). After COX regression analysis, the influence of pre-induction time on survival became insignificant, but patients who cooled slowest still had a better chance of survival at 28 days. In conclusion, a shorter delay before TTM was not associated with better clinical outcomes. However, patients who took longer to reach the target temperature had better hospital survival and neurological outcomes than those who were cooled more rapidly. A further prospective study was warranted to evaluate the appropriate time window of TTM.

Mild therapeutic hypothermia protects against inflammatory and proapoptotic processes in the rat model of cochlear implant trauma

OBJECTIVE

Mild therapeutic hypothermia (MTH) has been demonstrated to prevent residual hearing loss from surgical trauma associated with cochlear implant (CI) insertion. Here, we aimed to characterize the mechanisms of MTH-induced hearing preservation in CI in a well-established preclinical rodent model.

APPROACH

Rats were divided into four experimental conditions: MTH-treated and implanted cochleae, cochleae implanted under normothermic conditions, MTH only cochleae and un-operated cochleae (controls). Auditory brainstem responses (ABRs) were recorded at different time points (up to 84 days) to confirm long-term protection and safety of MTH locally applied to the cochlea for 20 min before and after implantation. Transcriptome sequencing profiling was performed on cochleae harvested 24 h post CI and MTH treatment to investigate the potential beneficial effects and underlying active gene expression pathways targeted by the temperature management.

RESULTS

MTH treatment preserved residual hearing up to 3 months following CI when compared to the normothermic CI group. In addition, MTH applied locally to the cochleae using our surgical approach was safe and did not affect hearing in the long-term. Results of RNA sequencing analysis highlight positive modulation of signaling pathways and gene expression associated with an activation of cellular inflammatory and immune responses against the mechanical damage caused by electrode insertion.

SIGNIFICANCE

These data suggest that multiple and possibly independent molecular pathways play a role in the protection of residual hearing provided by MTH against the trauma of cochlear implantation.

Neural Function Recovery and Safety of Mild Hypothermia Therapy Combined with Monosialotetrahexosylganglioside on Neonatal Asphyxia Complicated by Hypoxic Ischemic Encephalopathy

Objective

To explore the effect and safety of mild hypothermia therapy combined with monosialotetrahexosylganglioside (GM1) on neural function recovery of neonatal asphyxia complicated by hypoxic ischemic encephalopathy (HIE).

Methods

The clinical data of 90 neonates with HIE were retrospectively analyzed. According to the treatment methods, the neonates were divided into a routine group, a mild hypothermia group, and a combination group, with 30 cases in each group. The differences in neural function recovery, biochemical indexes, clinical signs recovery, efficacy, and complications were observed in the three groups after treatment.

Results

After treatment, the score of neonatal behavioral neurological assessment (NBNA) and level of superoxide dismutase (SOD) in the combination group were higher than those of the other two groups (P < 0.05). The levels of neuron-specific enolase (NSE), S-100β protein, and plasma neuropeptide Y (NPY) in the combination group were lower than those in the other two groups, and the recovery time of consciousness, muscle tension, and reflex was shorter (P < 0.05). The combination group showed higher total effective rate and lower incidence of complications as compared with the other two groups (P < 0.05).

Conclusion

Mild hypothermia therapy combined with GM1 for the treatment of neonatal asphyxia complicated by HIE can promote the recovery of neural function and reduce the incidence of complications in neonates.

Efficacy of different treatment times of mild cerebral hypothermia on oxidative factors and neuroprotective effects in neonatal patients with moderate/severe hypoxic-ischemic encephalopathy

Objective

To investigate the efficacy of different treatment times of mild cerebral hypothermia for treating moderate/severe hypoxic–ischemic encephalopathy (HIE) in neonatal patients and its effects on oxidative factors.

Methods

This prospective, randomized, controlled study included 92 neonatal patients with moderate/severe HIE and 30 controls. The patients with HIE received routine treatment, 48 hours of hypothermia, or 72 hours of hypothermia.

Results

Superoxide dismutase (SOD) values were significantly lower and malondialdehyde (MDA) and neuron-specific enolase (NSE) values were higher in patients with HIE than in controls before the study. After 24, 48, and 72 hours of treatment, SOD values in all patients with HIE gradually increased and MDA and NSE values gradually decreased. At 3, 7, and 10 days, the Neonatal Behavioral Neurological Assessment scores were highest in the mild hypothermia for 72 hours group than in the other groups. The Mental and Psychomotor Development Indices scores of the Bayley Scales were significantly higher in the mild hypothermia for 72 hours group than in the other groups.

Conclusion

Hypothermia treatment of 72 hours is better than 48 hours for improving oxidative conditions, reducing NSE values, and improving neurological behavior and development for neonates with moderate/severe HIE.

Mild hypothermia improves brain injury in rats with intracerebral hemorrhage by inhibiting IRAK2/NF-κB signaling pathway

OBJECTIVE

To explore the effect of mild hypothermia on nerve injury by establishing a rat model of intracerebral hemorrhage (ICH), and to clarify the specific molecular mechanism of mild hypothermia in improving brain injury in ICH rats.

METHODS

The rat model of ICH was established by collagenase injection. The neurological deficit score (NDS), brain tissue water detection, and Nissl staining were applied to detect the degree of brain injury. ELISA was used to analyze the expression of proinflammatory cytokines and serum nerve injury indexes. Flow cytometry and Western Blot were used to detect neuronal apoptosis.

RESULTS

Mild hypothermia treatment significantly improved the brain injury of the ICH rats and down-regulated the inflammatory response and oxidative stress in the brain tissue. Moreover, mild hypothermia also effectively inhibited IRAK2/NF-κB signaling pathway and thus affect neuronal apoptosis.

CONCLUSION

Mild hypothermia alleviates inflammatory response and neuronal apoptosis by inhibiting IRAK2/NF-κB signaling pathway in the ICH rats thus improving brain injury.