Minocycline fails to improve neurologic and histologic outcome after ventricular fibrillation cardiac arrest in rats.

BACKGROUND: Prolonged cardiac arrest (CA) produces extensive neuronal death and microglial proliferation and activation resulting in neuro-cognitive disabilities. Among other potential mechanisms, microglia have been implicated as triggers of neuronal death after hypoxic-ischemic insults. Minocycline is neuroprotective in some brain ischemia models, either by blunting the microglial response or by a direct effect on neurons. AIM: To improve survival, attenuate neurologic deficits, neuroinflammation, and histological damage after ventricular fibrillation (VF) CA in rats. METHODS: Adult male isoflurane-anesthetized rats were subjected to 6 min VF CA followed by 2 min resuscitation including chest compression, epinephrine, bicarbonate, and defibrillation. After return of spontaneous circulation (ROSC), rats were randomized to two groups: (1) Minocycline 90 mg/kg intraperitoneally (i.p.) at 15 min ROSC, followed by 22.5 mg/kg i.p. every 12 h for 72 h; and (2) Controls, receiving the same volume of vehicle (phosphate-buffered saline). The rats were kept normothermic during the postoperative course. Neurologic injury was assessed daily using Overall Performance Category (OPC; 1 = normal, 5 = dead) and Neurologic Deficit Score (NDS; 0% = normal, 100% = dead). Rats were sacrificed at 72 h. Neuronal degeneration (Fluoro-Jade C staining) and microglia proliferation (anti-Iba-1 staining) were quantified in four selectively vulnerable brain regions (hippocampus, striatum, cerebellum, cortex) by three independent reviewers masked to the group assignment. RESULTS: In the minocycline group, 8 out of 14 rats survived to 72 h compared to 8 out of 19 rats in the control group (P = 0.46). The degree of neurologic deficit at 72 h [median, (interquartile range)] was not different between survivors in minocycline vs controls: OPC 1.5 (1-2.75) vs 2 (1.25-3), P = 0.442; NDS 12 (2-20) vs 17 (7-51), P = 0.328) or between all studied rats. The number of degenerating neurons (minocycline vs controls, mean ± SEM: Hippocampus 58 ± 8 vs 76 ± 8; striatum 121 ± 43 vs 153 ± 32; cerebellum 20 ± 7 vs 22 ± 8; cortex 0 ± 0 vs 0 ± 0) or proliferating microglia (hippocampus 157 ± 15 vs 193 cortex 0 ± 0 vs 0 ± 0; 16; striatum 150 ± 22 vs 161 ± 23; cerebellum 20 ± 7 vs 22 ± 8; cortex 26 ± 6 vs 31 ± 7) was not different between groups in any region (all P > 0.05). Numerically, there were approximately 20% less degenerating neurons and proliferating microglia in the hippocampus and striatum in the minocycline group, with a consistent pattern of histological damage across the individual regions of interest. CONCLUSION: Minocycline did not improve survival and failed to confer substantial benefits on neurologic function, neuronal loss or microglial proliferation across multiple brain regions in our model of rat VF CA.

Thyroid surgery YouTube videos: estimating quality by surgeon characteristics and view rate.

BACKGROUND: With readily available material online we aimed: (I) to estimate the volume of thyroid surgery-related video content readily available to the surgical trainee; (II) to stratify the sources of thyroid surgery-related video content by source (patient, institution, surgeon, or other) and (III) to estimate the quality of the surgeon source by related scholarly output. METHODS: A search of YouTube, a widely used source of open-access video content, was undertaken using "thyroidectomy" as the search term. The first 100 "hits" were analyzed for source. When the video was surgeon-sourced, the surgeon's name was used in a PubMed author query for "thyroidectomy" and publications noted. RESULTS: Approximately 7,260 videos were returned using "thyroidectomy" as the search term. The first 100 "hits" were stratified by source, assuming the typical surgical trainee would not delve further into the list. The sources were primarily surgeons, followed by patient testimonials, and institutions. The surgeons were stratified by related publications listed in PubMed. The majority of surgeons were not published in thyroid surgery-related topics. CONCLUSIONS: Internet video content is an increasingly utilized source of surgical education. Since video content can be posted without peer review or confirmation of veracity, this study measures the variety of sources of thyroid surgery information. Individuals without thyroid surgery publication history posted the majority of surgeon-sourced video content, although this history serves only as a surrogate for an academic career. Trainees and educators alike should critically analyze the quality of video content.

Retrospective Review of Management and Outcomes of Pediatric Descending Mediastinitis.

OBJECTIVES: To review the management and outcomes of pediatric patients treated for descending mediastinitis at a single institution and contribute to an updated mortality rate. STUDY DESIGN: Case series with chart review. SETTING: Tertiary care pediatric hospital. SUBJECTS AND METHODS: This study is a 19-patient case series of all patients treated for descending mediastinitis at a tertiary pediatric hospital from 1997 to 2015, and it serves as an update to the case series published from this institution in 2008. Review of management included time to diagnosis, time to surgery, surgical procedures performed, and antibiotics administered. The primary outcomes measured were length of hospitalization and mortality. RESULTS: In addition to 8 previously reported patients, we identified 11 pediatric patients treated for descending mediastinitis in the period of review. All 19 patients were <18 months old, and all survived their hospitalization. Fourteen patients underwent surgical drainage at least twice. The median length of hospital stay was 15 days. Retropharyngeal abscess was the source of infection in 16 of 19 patients, and methicillin-resistant Staphylococcus aureus (MRSA) was the isolated organism in 14 of 15 positive cultures. CONCLUSION: This review represents the largest reported series of pediatric patients with descending mediastinitis. With 100% survival, our results suggest that pediatric descending mediastinitis can be safely managed by prompt surgical drainage. Broad-spectrum antibiotics covering MRSA and a low threshold for repeat surgical intervention have been an important part of our successful approach and may decrease length of stay.

Unique brain region-dependent cytokine signatures after prolonged hypothermic cardiac arrest in rats.

We previously showed that prolonged cardiac arrest (CA) produces neuronal death with microglial proliferation. Microglial proliferation, but not neuronal death, was attenuated by deeper hypothermia. Microglia are reportedly a major source of cytokines. In this study, we tested the hypotheses that (1) CA will result in highly specific regional and temporal increases in brain cytokines; and (2) these increases will be attenuated by deep hypothermia. Adult male Sprague-Dawley rats were subjected to rapid exsanguination. After 6 minutes of normothermic no-flow, different levels of hypothermia were induced by either ice-cold (IC) or room-temperature (RT) aortic flush. After 20 minutes CA, rats were resuscitated with cardiopulmonary bypass (CPB), and sacrificed at 6 or 24 hours. Rats subjected to CPB only (without CA) and shams (no CPB or CA) served as controls (n=6 per group). Cytokines were analyzed in cerebellum, cortex, hippocampus, and striatum. Immunofluorescence was used to identify cell types associated with individual cytokines. Intra-CA temperature was lower after IC versus RT flush (21°C vs. 28°C, p<0.05). At 6 hours, striatum showed a massive increase in interleukin (IL)-1α and tumor necrosis factor-alpha (TNF-α) (>100-fold higher than in hippocampus), which was attenuated by deeper hypothermia in the IC versus RT group. In contrast, IL-12 was 50-fold higher in hippocampus versus striatum. At 24 hours, cytokines decreased. In striatum, IL-1α colocalized with astrocytes while TNF-α colocalized with neurons. In hippocampus, IL-12 colocalized with hippocampal hilar neurons, the only region where neuronal degeneration was observed at 24 hours at both IC and RT groups. We report important temporo-spatial differences in the brain cytokine response to hypothermic CA, with a novel role of striatum. Astrocytes and neurons, but not microglia colocalized with individual cytokines. Hypothermia showed protective effects. These neuroinflammatory reactions precede neuronal death. New therapeutic strategies may need to target early regional neuroinflammation.

Minocycline attenuates brain tissue levels of TNF-α produced by neurons after prolonged hypothermic cardiac arrest in rats.

Neuro-cognitive disabilities are a well-recognized complication of hypothermic circulatory arrest. We and others have reported that prolonged cardiac arrest (CA) produces neuronal death and microglial proliferation and activation that are only partially mitigated by hypothermia. Microglia, and possibly other cells, are suggested to elaborate tumor necrosis factor alpha (TNF-α), which can trigger neuronal death cascades and exacerbate edema after CNS insults. Minocycline is neuroprotective in some brain ischemia models in part by blunting the microglial response. We tested the hypothesis that minocycline would attenuate neuroinflammation as reflected by brain tissue levels of TNF-α after hypothermic CA in rats. Rats were subjected to rapid exsanguination, followed by a 6 min normothermic CA. Hypothermia (30 °C) was then induced by an aortic saline flush. After a total of 20 min CA, resuscitation was achieved via cardiopulmonary bypass (CPB). After 5 min reperfusion, minocycline (90 mg kg−1; n = 6) or vehicle (PBS; n = 6) was given. Hypothermia (34 °C) was maintained for 6 h. Rats were sacrificed at 6 or 24 h. TNF-α was quantified (ELISA) in four brain regions (cerebellum, CEREB; cortex, CTX; hippocampus, HIP; striatum, STRI). Naïve rats (n = 6) and rats subjected to the same anesthesia and CPB but no CA served as controls (n = 6). Immunocytochemistry was used to localize TNF-α. Naïve rats and CPB controls had no detectable TNF-α in any brain region. CA markedly increased brain TNF-α. Regional differences were seen, with the highest TNF-α levels in striatum in CA groups (10-fold higher, P < 0.05 vs. all other brain regions). TNF-α was undetectable at 24 h. Minocycline attenuated TNF-α levels in CTX, HIP and STRI (P < 0.05). TNF-α showed unique co-localization with neurons. In conclusion, we report region-dependent early increases in brain TNF-α levels after prolonged hypothermic CA, with maximal increases in striatum. Surprisingly, TNF-α co-localized in neurons and not microglia. Minocycline attenuated TNF-α by approximately 50% but did not totally ablate its production. That minocycline decreased brain TNF-α levels suggests that it may represent a therapeutic adjunct to hypothermia in CA neuroprotection. University of Pittsburgh IACUC 0809278B-3.

Microglial depletion using intrahippocampal injection of liposome-encapsulated clodronate in prolonged hypothermic cardiac arrest in rats.

Trauma patients who suffer cardiac arrest (CA) from exsanguination rarely survive. Emergency preservation and resuscitation using hypothermia was developed to buy time for resuscitative surgery and delayed resuscitation with cardiopulmonary bypass (CPB), but intact survival is limited by neuronal death associated with microglial proliferation and activation. Pharmacological modulation of microglia may improve outcome following CA. Systemic injection of liposome-encapsulated clodronate (LEC) depletes macrophages. To test the hypothesis that intrahippocampal injection of LEC would attenuate local microglial proliferation after CA in rats, we administered LEC or PBS into the right or left hippocampus, respectively. After rapid exsanguination and 6min no-flow, hypothermia was induced by ice-cold (IC) or room-temperature (RT) flush. Total duration of CA was 20min. Pre-treatment (IC, RTpre) and post-treatment (RTpost) groups were studied, along with shams (cannulation only) and CPB controls. On day 7, shams and CPB groups showed neither neuronal death nor microglial activation. In contrast, the number of microglia in hippocampus in each individual group (IC, RTpre, RTpost) was decreased with LEC vs. PBS by ∼34-46% (P<0.05). Microglial proliferation was attenuated in the IC vs. RT groups (P<0.05). Neuronal death did not differ between hemispheres or IC vs. RT groups. Thus, intrahippocampal injection of LEC attenuated microglial proliferation by ∼40%, but did not alter neuronal death. This suggests that microglia may not play a pivotal role in mediating neuronal death in prolonged hypothermic CA. This novel strategy provides us with a tool to study the specific effects of microglia in hypothermic CA.