Protocol paper: kainic acid excitotoxicity-induced spinal cord injury paraplegia in Sprague-Dawley rats.

BACKGROUND: Excitotoxicity-induced in vivo injury models are vital to reflect the pathophysiological features of acute spinal cord injury (SCI) in humans. The duration and concentration of chemical treatment controls the extent of neuronal cell damage. The extent of injury is explained in relation to locomotor and behavioural activity. Several SCI in vivo methods have been reported and studied extensively, particularly contusion, compression, and transection models. These models depict similar pathophysiology to that in humans but are extremely expensive (contusion) and require expertise (compression). Chemical excitotoxicity-induced SCI models are simple and easy while producing similar clinical manifestations. The kainic acid (KA) excitotoxicity model is a convenient, low-cost, and highly reproducible animal model of SCI in the laboratory. The basic impactor approximately cost between 10,000 and 20,000 USD, while the kainic acid only cost between 300 and 500 USD, which is quite cheap as compared to traditional SCI method. METHODS: In this study, 0.05 mM KA was administered at dose of 10 µL/100 g body weight, at a rate of 10 µL/min, to induce spinal injury by intra-spinal injection between the T12 and T13 thoracic vertebrae. In this protocol, detailed description of a dorsal laminectomy was explained to expose the spinal cord, following intra-spinal kainic acid administration at desired location. The dose, rate and technique to administer kainic acid were explained extensively to reflect a successful paraplegia and spinal cord injury in rats. The postoperative care and complication post injury of paraplegic laboratory animals were also explained, and necessary requirements to overcome these complications were also described to help researcher. RESULTS: This injury model produced impaired hind limb locomotor function with mild seizure. Hence this protocol will help researchers to induce spinal cord injury in laboratories at extremely low cost and also will help to determine the necessary supplies, methods for producing SCI in rats and treatments designed to mitigate post-injury impairment. CONCLUSIONS: Kainic acid intra-spinal injection at the concentration of 0.05 mM, and rate 10 µL/min, is an effective method create spinal injury in rats, however more potent concentrations of kainic acid need to be studied in order to create severe spinal injuries.

A genomic-based vision on the genetic diversity and key performance traits in selectively bred Arctic charr (Salvelinus alpinus).

Routine implementation of genomic information for guiding selection decisions is not yet common in the majority of aquaculture species. Reduced representation sequencing approaches offer a cost-effective solution for obtaining genome-wide information in species with a limited availability of genomic resources. In the current study, we implemented double-digest restriction site-associated DNA sequencing (ddRAD-seq) on an Arctic charr strain with the longest known history of selection (approximately 40 years) aiming to improve selection decisions. In total, 1730 animals reared at four different farms in Sweden and spanning from year classes 2013-2017 were genotyped using ddRAD-seq. Approximately 5000 single nucleotide polymorphisms (SNPs) were identified, genetic diversity-related metrics were estimated, and genome-wide association studies (GWAS) for body length at different time points and age of sexual maturation were conducted. Low genetic differentiation amongst animals from the different farms was observed based on both the results from pairwise F st values and principal component analysis (PCA). The existence of associations was investigated between the mean genome-wide heterozygosity of each full-sib family (year class 2017) and the corresponding inbreeding coefficient or survival to the eyed stage. A moderate correlation (-0.33) was estimated between the mean observed heterozygosity of each full-sib family and the corresponding inbreeding coefficient, while no linear association was obtained with the survival to the eyed stage. GWAS did not detect loci with major effect for any of the studied traits. However, genomic regions explaining more than 1% of the additive genetic variance for either studied traits were suggested across 14 different chromosomes. Overall, key insights valuable for future selection decisions of Arctic charr have been obtained, suggesting ddRAD as an attractive genotyping platform for obtaining genome-wide information in a cost-effective manner.

Protocol paper: kainic acid excitotoxicity-induced spinal cord injury paraplegia in Sprague-Dawley rats

BACKGROUND: Excitotoxicity-induced in vivo injury models are vital to reflect the pathophysiological features of acute spinal cord injury (SCI) in humans. The duration and concentration of chemical treatment controls the extent of neuronal cell damage. The extent of injury is explained in relation to locomotor and behavioural activity. Several SCI in vivo methods have been reported and studied extensively, particularly contusion, compression, and transection models. These models depict similar pathophysiology to that in humans but are extremely expensive (contusion) and require expertise (compression). Chemical excitotoxicity-induced SCI models are simple and easy while producing similar clinical manifestations. The kainic acid (KA) excitotoxicity model is a convenient, low-cost, and highly reproducible animal model of SCI in the laboratory. The basic impactor approximately cost between 10,000 and 20,000 USD, while the kainic acid only cost between 300 and 500 USD, which is quite cheap as compared to traditional SCI method. METHODS: In this study, 0.05 mM KA was administered at dose of 10 µL/100 g body weight, at a rate of 10 µL/min, to induce spinal injury by intra-spinal injection between the T12 and T13 thoracic vertebrae. In this protocol, detailed description of a dorsal laminectomy was explained to expose the spinal cord, following intra-spinal kainic acid administration at desired location. The dose, rate and technique to administer kainic acid were explained extensively to reflect a successful paraplegia and spinal cord injury in rats. The postoperative care and complication post injury of paraplegic laboratory animals were also explained, and necessary requirements to overcome these complications were also described to help researcher. RESULTS: This injury model produced impaired hind limb locomotor function with mild seizure. Hence this protocol will help researchers to induce spinal cord injury in laboratories at extremely low cost and also will help to determine the necessary supplies, methods for producing SCI in rats and treatments designed to mitigate post-injury impairment. CONCLUSIONS: Kainic acid intra-spinal injection at the concentration of 0.05 mM, and rate 10 µL/min, is an effective method create spinal injury in rats, however more potent concentrations of kainic acid need to be studied in order to create severe spinal injuries.

Spinal Cord Injury: Pathophysiology, Multimolecular Interactions, and Underlying Recovery Mechanisms.

Spinal cord injury (SCI) is a destructive neurological and pathological state that causes major motor, sensory and autonomic dysfunctions. Its pathophysiology comprises acute and chronic phases and incorporates a cascade of destructive events such as ischemia, oxidative stress, inflammatory events, apoptotic pathways and locomotor dysfunctions. Many therapeutic strategies have been proposed to overcome neurodegenerative events and reduce secondary neuronal damage. Efforts have also been devoted in developing neuroprotective and neuro-regenerative therapies that promote neuronal recovery and outcome. Although varying degrees of success have been achieved, curative accomplishment is still elusive probably due to the complex healing and protective mechanisms involved. Thus, current understanding in this area must be assessed to formulate appropriate treatment modalities to improve SCI recovery. This review aims to promote the understanding of SCI pathophysiology, interrelated or interlinked multimolecular interactions and various methods of neuronal recovery i.e., neuroprotective, immunomodulatory and neuro-regenerative pathways and relevant approaches.

PLGA/xylitol nanoparticles enhance antibiofilm activity via penetration into biofilm extracellular polymeric substances.

Biofilms are gelatinous masses of microorganisms attached to wound surfaces. Previous studies suggest that biofilms generate resistance towards antibiotic treatments. It was reported that hydrogels containing xylitol and antibiotic combinations produced additive antibiofilm inhibition. However, hydrogel formulations lack specificity, due to which xylitol cannot penetrate into the biofilm matrix and gets easily degraded by bacterial beta lactamase enzymes. It was hypothesized that the incorporation of xylitol in PLGA (polylactic-co-glycolic acid) nanoparticles will enhance penetration into the EPS (extra polymeric substance) component of the biofilm matrix and potentially overcome the antibiotic resistance associated with the biofilms. The purpose of this study was to develop PLGA nanoparticles loaded with xylitol, which will enhance bacterial biofilm penetration. The nanoparticles were loaded with different amounts of xylitol (0.5-5% w/w) and characterized for physiochemical and drug release properties. The metabolic antibiofilm activity of the PLGA nanoparticles containing xylitol was demonstrated by an XTT assay using as references the cultures of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) and the polymicrobial biofilms of both bacterial strains. Live/dead viability staining was also performed to investigate the viability ratio of bacterial cells present in the biofilms. The biofilm penetration study of the PLGA nanoparticles was assessed by combining the nanoparticles with conjugated concanavalin A (Con A)-fluorescein isothiocyanate (FITC) and by viewing using confocal laser scanning electron microscopy (CLSM). In conclusion, the PLGA nanoparticles loaded with xylitol were successfully developed and were found to promote the antibiofilm activity of xylitol in infected wounds.

Hydrogels Containing Antibiofilm and Antimicrobial Agents Beneficial for Biofilm-Associated Wound Infection: Formulation Characterizations and In vitro Study.

Bacterial biofilm which adheres onto wound surface is shown to be impervious to antibiotics and this in turn delays wound healing. Previous studies showed that antibiofilm agents such as xylitol and ethylenediaminetetraacetic acid (EDTA) prevent bacterial adherence onto surfaces. Formulation of a wound dressing containing antibiofilm agents may be a plausible strategy in breaking the biofilm on wound surfaces and at the same time increase the efficacy of the antibiotic. The purpose of this study was to develop hydrogel formulations containing antibiofilm agents along with antibiotic (gentamicin) for bacterial biofilm-associated wound infection. Sodium carboxymethyl cellulose (NaCMC) hydrogels loaded with antibiofilm agents and antibiotic were prepared. The hydrogels were characterized for their physical properties, rheology, Fourier transform infrared spectroscopy (FTIR), drug content uniformity, differential scanning calorimetry (DSC) and in vitro drug release study. The antibiofilm (Crystal Violet staining and XTT assay) and antibacterial performances of the hydrogels against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli were assessed in vitro. The formulated hydrogels showed adequate release of both antibiofilm agents (xylitol and EDTA). Both antimicrobial and antibiofilm tests showed promising results and demonstrated that the combination of xylitol, EDTA, and gentamicin had an additive effect against both Gram-positive and Gram-negative bacteria. In summary, NaCMC (sodium carboxymethyl cellulose) hydrogels containing the combination of antimicrobial and antibiofilm agents were successfully developed and this can be a new strategy in combating biofilm in wound infection which in turn accelerate wound healing.