In Vitro and In Vivo Assessment of the Infection Resistance and Biocompatibility of Small-Molecule-Modified Polyurethane Biomaterials.

Bacterial intracellular nucleotide second messenger signaling is involved in biofilm formation and regulates biofilm development. Interference with the bacterial nucleotide second messenger signaling provides a novel approach to control biofilm formation and limit microbial infection in medical devices. In this study, we tethered small-molecule derivatives of 4-arylazo-3,5-diamino-1H-pyrazole on polyurethane biomaterial surfaces and measured the biofilm resistance and initial biocompatibility of modified biomaterials in in vitro and in vivo settings. Results showed that small-molecule-modified surfaces significantly reduced the Staphylococcal epidermidis biofilm formation compared to unmodified surfaces and decreased the nucleotide levels of c-di-AMP in biofilm cells, suggesting that the tethered small molecules interfere with intracellular nucleotide signaling and inhibit biofilm formation. The hemocompatibility assay showed that the modified polyurethane films did not induce platelet activation or red blood cell hemolysis but significantly reduced plasma coagulation and platelet adhesion. The cytocompatibility assay with fibroblast cells showed that small-molecule-modified surfaces were noncytotoxic and cells appeared to be proliferating and growing on modified surfaces. In a 7-day subcutaneous infection rat model, the polymer samples were implanted in Wistar rats and inoculated with bacteria or PBS. Results show that modified polyurethane significantly reduced bacteria by ∼2.5 log units over unmodified films, and the modified polymers did not lead to additional irritation/toxicity to the animal tissues. Taken together, the results demonstrated that small molecules tethered on polymer surfaces remain active, and the modified polymers are biocompatible and resistant to microbial infection in vitro and in vivo.

Chronic Cannabigerol as an Effective Therapeutic for Cisplatin-Induced Neuropathic Pain.

Cannabigerol (CBG), derived from the cannabis plant, acts as an acute analgesic in a model of cisplatin-induced peripheral neuropathy (CIPN) in mice. There are no curative, long-lasting treatments for CIPN available to humans. We investigated the ability of chronic CBG to alleviate mechanical hypersensitivity due to CIPN in mice by measuring responses to 7 and 14 days of daily CBG. We found that CBG treatment (i.p.) for 7 and 14 consecutive days significantly reduced mechanical hypersensitivity in male and female mice with CIPN and reduced pain sensitivity up to 60-70% of baseline levels (p < 0.001 for all), 24 h after the last injection. Additionally, we found that daily treatment with CBG did not evoke tolerance and did not incur significant weight change or adverse events. The efficacy of CBG was independent of the estrous cycle phase. Therefore, chronic CBG administration can provide at least 24 h of antinociceptive effect in mice. These findings support the study of CBG as a long-lasting neuropathic pain therapy, which acts without tolerance in both males and females.

Severe Anemia in Sprague-Dawley Rats After Roux-en-Y Gastric Bypass Surgery.

Roux-en-Y gastric bypass (RYGB) surgery is one of the most commonly performed bariatric procedures for weight loss in humans. However, this procedure is not risk-free, and patients may experience complications that include small bowel obstruction, gastrointestinal bleeding, chronic diarrhea, ulcers, malnutrition, and anemia. In particular, anemia is a recognized long-term complication and can be severe. Rats have been used as a model to study the effects of gastric bypass surgeries. They can experience similar complications as people, but the development of severe anemia has not previously been reported in rats. We observed 2 cases of severe anemia in female Sprague-Dawley rats after RYGB surgery. These cases prompted us to further investigate the frequency and severity of anemia after RYGB in rats. Blood work and necropsies were performed on 9 additional female Sprague-Dawley rats (5 with RYGB, 4 with sham surgery). In these 9 rats, only one had signs of clinical anemia. These 3 anemic rats displayed moderate to severe pallor of the eyes and ears. Necropsy findings in anemic RYGB rats included pale internal organs and eccentric heart enlargement, which led to a significantly higher heart:body weight ratio in RYGB rats as compared with sham controls. Anemic rats had either a macrocytic normochromic anemia, consistent with vitamin B12 or folate deficiency, or microcytic hypochromic anemia, indicative of iron deficiency. Researchers who perform RYGB surgery in rats should be aware of the potential complication of severe anemia. Plans for the diagnosis and management of this complication and the development of criteria for humane endpoints for severe anemia are recommended as a refinement to these studies.

Antibody Titers and Seroconversion Kinetics of Outbred Swiss and Heterozygous Nude Soiled-bedding Sentinels for Murine Norovirus and Mouse Hepatitis Virus.

Sentinel animals remain a common means of evaluating rodent health in research colonies. An evaluation of our sentinel program revealed that using Crl:CD1(ICR)-Elite (CD1-E) mice was expensive, occasionally disrupted by limited supply, and minimally responsive to the 3Rs. This evaluation prompted us to explore the use of CRL:NU-Foxn1nu/+ (Het-nude) mice as soiled-bedding sentinel (SBS) animals. Het-nude mice are a byproduct of breeding outbred athymic nude mice and are reared in isolators, with similar health status as CD1-E. Het-nude mice have a thymus, but may have smaller thymic size and fewer bone marrow stem cells than do wildtype controls, suggesting that Het-nude mice might not be immunologically normal. This study compared the antibody titer and seroconversion kinetics of Het-nude and CD1-E SBS to murine norovirus (MNV) and mouse hepatitis virus (MHV). Het-nude and CD1-E female SBS (n = 22 mice of each stock) were housed continuously on soiled bedding collected from MNV-positive or MNV- and MHV-positive colonies at cage changes. Blood was collected for serology at 3, 9 and 12 to 19 wk after the start of soiled bedding exposure. Antibody titers to MNV or MHV did not differ significantly between Het-nude and CD1-E mice. A significant relationship was found between weeks of exposure and titer levels with an increase in titer over the testing period. This study supports the possible use of Het-nude mice as SBS, given that their antibody responses to MNV and MHV are equivalent to those of CD1-E mice.

Housing conditions modulate the severity of Mycoplasma pulmonis infection in mice deficient in class A scavenger receptor.

Mycoplasmosis is a frequent causative microbial agent of community-acquired pneumonia and has been linked to exacerbation of chronic obstructive pulmonary disease. The macrophage class A scavenger receptor (SRA) facilitates the clearance of noxious particles, oxidants, and infectious organisms by alveolar macrophages. We examined wildtype and SRA(-/-) mice, housed in either individually ventilated or static filter-top cages that were cycled with fresh bedding every 14 d, as a model of gene-environment interaction on the outcome of pulmonary Mycoplasma pulmonis infection. Intracage NH3 gas measurements were recorded daily prior to infection. Mice were intranasally infected with 1 × 10(7) cfu M. pulmonis UAB CT and evaluated at 3, 7, and 14 d after inoculation. Wildtype mice cleared 99.5% of pulmonary M. pulmonis by 3 d after infection but remained chronically infected through the study. SRA (-/-) mice were chronically infected with 40-fold higher mycoplasma numbers than were wildtype mice. M. pulmonis caused a chronic mixed inflammatory response that was accompanied with high levels of IL1ß, KC, MCP1, and TNFα in SRA(-/-) mice, whereas pulmonary inflammation in WT mice was represented by a monocytosis with elevation of IL1ß. Housing had a prominent influence on the severity and persistence of mycoplasmosis in SRA(-/-) mice. SRA(-/-) mice housed in static cages had an improved recovery and significant changes in surfactant proteins SPA and SPD compared with baseline levels. These results indicate that SRA is required to prevent chronic mycoplasma infection of the lung. Furthermore, environmental conditions may exacerbate chronic inflammation in M. pulmonis-infected SRA(-/-) mice.

Multiple complex congenital malformations in a rabbit kit (Oryctolagus cuniculi).

Congenital malformations may occur during early embryogenesis in cases of genetic abnormalities or various environmental factors. Affected subjects most often have only one or 2 abnormalities; subjects rarely have several unrelated congenital defects. Here we describe a case of a stillborn New Zealand white rabbit with multiple complex congenital malformations, including synophthalmia, holoprosencephaly, gastroschisis, and a supernumerary hindlimb, among other anomalies. There was no historical exposure to teratogens or other known environmental causes. Although not confirmed, this case was most likely a rare spontaneous genetic event.