COVID-19 Infection Enhances Susceptibility to Oxidative Stress-Induced Parkinsonism.

BACKGROUND: Viral induction of neurological syndromes has been a concern since parkinsonian-like features were observed in patients diagnosed with encephalitis lethargica subsequent to the 1918 influenza pandemic. Given the similarities in the systemic responses after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with those observed after pandemic influenza, there is a question whether a similar syndrome of postencephalic parkinsonism could follow coronavirus disease 2019 infection. OBJECTIVE: The goal of this study was to determine whether prior infection with SARS-CoV-2 increased sensitivity to a mitochondrial toxin known to induce parkinsonism. METHODS: K18-hACE2 mice were infected with SARS-CoV-2 to induce mild-to-moderate disease. After 38 days of recovery, mice were administered a non-lesion-inducing dose of the parkinsonian toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and euthanized 7 days later. Subsequent neuroinflammation and substantia nigra pars compacta (SNpc) dopaminergic (DA) neuron loss were determined and compared with SARS-CoV-2 or MPTP alone. RESULTS: K18-hACE2 mice infected with SARS-CoV-2 or MPTP showed no SNpc DA neuron loss after MPTP. In mice infected and recovered from SARS-CoV-2 infection, MPTP induced a 23% or 19% greater loss of SNpc DA neurons than SARS-CoV-2 or MPTP, respectively (P < 0.05). Examination of microglial activation showed a significant increase in the number of activated microglia in both the SNpc and striatum of the SARS-CoV-2 + MPTP group compared with SARS-CoV-2 or MPTP alone. CONCLUSIONS: Our observations have important implications for long-term public health, given the number of people who have survived SARS-CoV-2 infection, as well as for future public policy regarding infection mitigation. However, it will be critical to determine whether other agents known to increase risk for PD also have synergistic effects with SARS-CoV-2 and are abrogated by vaccination. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Long-term efficacy of pressure immobilization bandages in a porcine model of coral snake envenomation.

BACKGROUND: Pressure immobilization bandages delay mortality for 8 hours after coral snake envenomation, but long-term efficacy has not been established. OBJECTIVE: The objective of this study is to determine the long-term efficacy of pressure immobilization bandages after coral snake envenomation in the absence of antivenom therapy. METHODS: A randomized, observational pilot study was conducted. Ten pigs (17.3-25.6 kg) were sedated, intubated for 5 hours, and injected subcutaneously with 10 mg of lyophilized Micrurus fulvius venom resuspended in water. Pigs were randomly assigned to a control group (no treatment) or a treatment group (compression bandage and splint) approximately 1 minute after envenomation. Bandage pressure was not controlled. Pigs were monitored daily for 21 days for signs of respiratory depression, decreased oxygen saturations, and paralysis. In case of respiratory depression, pigs were humanely euthanized and time to death recorded. Statistical analysis was performed with Fisher exact test, Mann-Whitney U test, and Kaplan-Meier survival curve as appropriate. RESULTS: Median survival time of control animals was 307 minutes compared with 1172 minutes in treated animals (P = .10). Sixty percent of pigs in the treatment group survived to 24 hours vs 0% of control pigs (P = .08). Two of the treatment pigs survived to the end point of 21 days but showed necrosis of the distal lower extremity. CONCLUSIONS: Long-term survival after coral snake envenomation is possible in the absence of antivenom with the use of pressure immobilization bandages. The applied pressure of the bandage is critical to allowing survival without necrosis. Future studies should be designed to accurately monitor the pressures applied.

Emerging Role of Kinin B1 Receptor in Persistent Neuroinflammation and Neuropsychiatric Symptoms in Mice Following Recovery from SARS-CoV-2 Infection.

Evidence suggests that patients with long COVID can experience neuropsychiatric, neurologic, and cognitive symptoms. However, these clinical data are mostly associational studies complicated by confounding variables, thus the mechanisms responsible for persistent symptoms are unknown. Here we establish an animal model of long-lasting effects on the brain by eliciting mild disease in K18-hACE2 mice. Male and female K18-hACE2 mice were infected with 4 × 103 TCID50 of SARS-CoV-2 and, following recovery from acute infection, were tested in the open field, zero maze, and Y maze, starting 30 days post infection. Following recovery from SARS-CoV-2 infection, K18-hACE2 mice showed the characteristic lung fibrosis associated with SARS-CoV-2 infection, which correlates with increased expression of the pro-inflammatory kinin B1 receptor (B1R). These mice also had elevated expression of B1R and inflammatory markers in the brain and exhibited behavioral alterations such as elevated anxiety and attenuated exploratory behavior. Our data demonstrate that K18-hACE2 mice exhibit persistent effects of SARS-CoV-2 infection on brain tissue, revealing the potential for using this model of high sensitivity to SARS-CoV-2 to investigate mechanisms contributing to long COVID symptoms in at-risk populations. These results further suggest that elevated B1R expression may drive the long-lasting inflammatory response associated with SARS-CoV-2 infection.

Suppression of murine osteoarthritis by 4-methylumbelliferone.

Using in vitro models, we previously reported that 4-methylumbelliferone (4-MU) blocked many of the pro-catabolic features of activated chondrocytes. 4-MU also blocked safranin O loss from human cartilage explants exposed to interleukin 1ß (IL1ß) in vitro. However, the mechanism for this chondroprotective effect was independent of the action of 4-MU as a hyaluronan (HA) inhibitor. Interestingly, overexpression of HA synthase 2 (HAS2) also blocked the same pro-catabolic features of activated chondrocytes as 4-MU via a mechanism independent of extracellular HA accumulation. Data suggest that altering UDP-sugars may be behind these changes in chondrocyte metabolism. However, all of our previous experiments with 4-MU or HAS2 overexpression were performed in vitro. The purpose of this study was to confirm whether 4-MU was effective at limiting the effects of osteoarthritis (OA) on articular cartilage in vivo. The progression of OA was evaluated after destabilization of the medial meniscus (DMM) surgery on C57BL/6 mice in the presence or absence of 4-MU-containing chow. Mice fed 4-MU after DMM surgery exhibited significant suppression of OA starting from an early stage in vivo. Mice fed 4-MU exhibited lower OARSI scores after DMM; reduced osteophyte formation and reduced MMP3 and MMP13 immunostaining. 4-MU also exerted pronounced chondroprotective effects on murine joint cartilage exposed to IL1ß in vitro and, blocked IL1ß-enhanced lactate production in cartilage explants. Therefore, 4-MU is effective at significantly reducing the loss of proteoglycan and reducing MMP production both in vitro and in vivo as well as cartilage damage and osteophyte formation in vivo after DMM. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. 38:1122-1131, 2020.

Nontraditional Laboratory Animal Species (Cephalopods, Fish, Amphibians, Reptiles, and Birds).

Aquatic vertebrates and cephalopods, amphibians, reptiles, and birds offer unique safety and occupational health challenges for laboratory animal personnel. This paper discusses environmental, handling, and zoonotic concerns associated with these species.

Amphibians used in research and teaching.

Amphibians have long been utilized in scientific research and in education. Historically, investigators have accumulated a wealth of information on the natural history and biology of amphibians, and this body of information is continually expanding as researchers describe new species and study the behaviors of these animals. Amphibians evolved as models for a variety of developmental and physiological processes, largely due to their unique ability to undergo metamorphosis. Scientists have used amphibian embryos to evaluate the effects of toxins, mutagens, and teratogens. Likewise, the animals are invaluable in research due to the ability of some species to regenerate limbs. Certain species of amphibians have short generation times and genetic constructs that make them desirable for transgenic and knockout technology, and there is a current national focus on developing these species for genetic and genomic research. This group of vertebrates is also critically important in the investigation of the inter-relationship of humans and the environment based on their sensitivity to climatic and habitat changes and environmental contamination.

Efficacy of Trypsin in Treating Coral Snake Envenomation in the Porcine Model.

Antivenom is the definitive treatment for venomous snakebites. Alternative treatments warrant investigation because antivenom is sometimes unavailable, expensive, and can have deleterious side effects. This study assesses the efficacy of trypsin to treat coral snake envenomation in an in vivo porcine model. A randomized, blinded study was conducted. Subjects were 13 pigs injected subcutaneously with 1 mL of eastern coral snake venom (10 mg/mL) in the right distal hind limb. After 1 min, subjects were randomized to have the envenomation site injected with either 1 mL of saline or 1 mL of trypsin (100 mg/mL) by a blinded investigator. Clinical endpoint was survival for 72 h or respiratory depression defined as respiratory rate <15 breaths per minute, falling pulse oximetry, or agonal respirations. Fisher's exact t test was used for between group comparisons. Average time to toxicity for the saline control was 263 min (191-305 min). The development of respiratory depression occurred more frequently in control pigs than treated pigs (p = 0.009). Four of the six pigs that received trypsin survived to the end of the 3-day study. No control pigs survived. Two of the trypsin treatment pigs died with times to toxicity of 718 and 971 min. Survival to 12 and 24 h was significantly greater in the trypsin treatment group (p = 0.002, p = 0.009, respectively). Local injection of trypsin, a proteolytic enzyme, at the site of envenomation decreased the toxicity of eastern coral snake venom and increased survival significantly. Further investigation is required before these results can be extended to human snakebites.

Reptiles and amphibians as laboratory animals.

Although reptiles and amphibians have long been used in biomedical research, few in the arena understand their health and husbandry needs. The author provides an introduction to the successful maintenance of reptiles and amphibians in the laboratory environment.

A randomized controlled trial of trypsin to treat brown recluse spider bites in Guinea pigs.

Brown recluse spider bites result in necrotic skin lesions for which there is no known antidote. Since venom toxins are proteins, a proteolytic enzyme like trypsin might be effective in reducing toxicity. The aim of this study was to conduct a randomized controlled trial of trypsin to treat brown recluse spider bites in guinea pigs. Subjects were 18 female guinea pigs. Anesthesia for injections was inhaled isoflurane. Analgesia was 0.05 mg/kg of buprenorphine twice a day as needed. Intervention was intradermal injection of 30 µg of brown recluse venom (Spider Pharm, Yarnell, AZ). Immediately after envenomation, subjects were randomized to two groups of nine: trypsin 10 µg in 1 mL normal saline and 1 mL of normal saline. The primary outcome was lesion area over a 10-day time period. Statistical analysis was performed with repeated measures ANOVA. Mean lesion area was smaller but not statistically different in the placebo group. Maximum lesion size occurred at day 4 in both groups, when lesion area was 76.1 ± 108.2 mm(2) in the placebo group and 149.7 ± 127.3 mm(2) in the treatment group. P value was 0.15 for placebo vs. treatment. This study did not establish a role for trypsin as a treatment for brown recluse spider bites in a guinea pig model.

The Bacteroides fragilis transcriptome response to oxygen and H2O2: the role of OxyR and its effect on survival and virulence.

The intestinal anaerobic symbiont, Bacteroides fragilis, is highly aerotolerant and resistant to H(2)O(2). Analysis of the transcriptome showed that expression of 45% of the genome was significantly affected by oxidative stress. The gene expression patterns suggested that exposure to oxidative stress induced an acute response to rapidly minimize the immediate effects of reactive oxygen species, then upon extended exposure a broad metabolic response was induced. This metabolic response induced genes encoding enzymes that can supply reducing power for detoxification and restore energy-generating capacity. An integral aspect of the metabolic response was downregulation of genes related to translation and biosynthesis which correlated with decreased growth and entry into a stationary phase-like growth state. Examination of oxyR mutants showed that they were impaired for the acute response and they induced the expanded metabolic response with only minimal exposure to stress. The oxyR mutants were more sensitive to oxidants in vitro and in vivo they were attenuated in an intra-abdominal abscess infection model. Aerotolerance and resistance to oxidative stress are physiological adaptations of B. fragilis to its environment that enhance survival in extra-intestinal sites and promote opportunistic infections.