Functionality of the Na+-translocating NADH:quinone oxidoreductase and quinol:fumarate reductase from Prevotella bryantii inferred from homology modeling.

Members of the family Prevotellaceae are Gram-negative, obligate anaerobic bacteria found in animal and human microbiota. In Prevotella bryantii, the Na+-translocating NADH:quinone oxidoreductase (NQR) and quinol:fumarate reductase (QFR) interact using menaquinone as electron carrier, catalyzing NADH:fumarate oxidoreduction. P. bryantii NQR establishes a sodium-motive force, whereas P. bryantii QFR does not contribute to membrane energization. To elucidate the possible mode of function, we present 3D structural models of NQR and QFR from P. bryantii to predict cofactor-binding sites, electron transfer routes and interaction with substrates. Molecular docking reveals the proposed mode of menaquinone binding to the quinone site of subunit NqrB of P. bryantii NQR. A comparison of the 3D model of P. bryantii QFR with experimentally determined structures suggests alternative pathways for transmembrane proton transport in this type of QFR. Our findings are relevant for NADH-dependent succinate formation in anaerobic bacteria which operate both NQR and QFR.

The low mutational flexibility of the EPSP synthase in Bacillus subtilis is due to a higher demand for shikimate pathway intermediates.

Glyphosate (GS) inhibits the 5-enolpyruvyl-shikimate-3-phosphate (EPSP) synthase that is required for aromatic amino acid, folate and quinone biosynthesis in Bacillus subtilis and Escherichia coli. The inhibition of the EPSP synthase by GS depletes the cell of these metabolites, resulting in cell death. Here, we show that like the laboratory B. subtilis strains also environmental and undomesticated isolates adapt to GS by reducing herbicide uptake. Although B. subtilis possesses a GS-insensitive EPSP synthase, the enzyme is strongly inhibited by GS in the native environment. Moreover, the B. subtilis EPSP synthase mutant was only viable in rich medium containing menaquinone, indicating that the bacteria require a catalytically efficient EPSP synthase under nutrient-poor conditions. The dependency of B. subtilis on the EPSP synthase probably limits its evolvability. In contrast, E. coli rapidly acquires GS resistance by target modification. However, the evolution of a GS-resistant EPSP synthase under non-selective growth conditions indicates that GS resistance causes fitness costs. Therefore, in both model organisms, the proper function of the EPSP synthase is critical for the cellular viability. This study also revealed that the uptake systems for folate precursors, phenylalanine and tyrosine need to be identified and characterized in B. subtilis.

Conformational coupling of redox-driven Na+-translocation in Vibrio cholerae NADH:quinone oxidoreductase.

In the respiratory chain, NADH oxidation is coupled to ion translocation across the membrane to build up an electrochemical gradient. In the human pathogen Vibrio cholerae, the sodium-pumping NADH:quinone oxidoreductase (Na+-NQR) generates a sodium gradient by a so far unknown mechanism. Here we show that ion pumping in Na+-NQR is driven by large conformational changes coupling electron transfer to ion translocation. We have determined a series of cryo-EM and X-ray structures of the Na+-NQR that represent snapshots of the catalytic cycle. The six subunits NqrA, B, C, D, E, and F of Na+-NQR harbor a unique set of cofactors that shuttle the electrons from NADH twice across the membrane to quinone. The redox state of a unique intramembranous [2Fe-2S] cluster orchestrates the movements of subunit NqrC, which acts as an electron transfer switch. We propose that this switching movement controls the release of Na+ from a binding site localized in subunit NqrB.

Comparing United States and European Union academic animal programs: Organization, operation, and services offered.

The Yale Animal Resource Cost and Benchmarking survey©, conducted in US academic Animal Research/Resource Centers (ARC), was modified to capture similar thematic information in European Union (EU; including the non-EU countries Switzerland and the UK) academic ARCs, which are members of the League of European Research Universities (LERU). Participating institutions came from Denmark, England, Finland, France, Germany, Ireland, Italy, Netherlands, Scotland, Spain, and Switzerland. Survey data analysis suggests that: (a) in LERU programs, it is common to have more than one ARC under the umbrella of a single institution with organizational "lumping" of the financial, regulatory, and/or operational tasks under one administrative unit; (b) accreditation by an outside agency (e.g., the Association for the Assessment and Accreditation of Laboratory Animal Care) is more common in US than LERU ARCs; (c) LERU ARCs are responsible for murine breeding, which contrasts with US ARCs, where ∼40% of rodent breeding is managed by researchers; (d) cryopreservation is the most frequently requested fee-for-service offering among LERU participants (75% of participants) compared to 30% of US participants; (e) like US programs, almost all LERU programs have mice and rats, but fewer LERU programs have nonhuman primates (NHPs), and none have dogs on census; (f) LERU ARCs have about an equal amount of vivarium housing and procedure space, while US facilities have twice as much housing as procedure space; (g) a higher percentage of LERU colonies are free of Helicobacter and murine norovirus compared to US colonies; and (h) more LERU ARCs used environmental microbiologic monitoring of rodent colonies compared to US programs.

Comparing United States and European Union academic animal programs: Finances.

The Yale Animal Resource Cost and Benchmarking survey, conducted in United States (US) academic animal research/resource centres (ARC), was modified to capture similar information in European Union (EU) (including the non-EU countries Switzerland and the United Kingdom) academic ARCs, who are members of the League of European Research Universities (LERU). Participating institutions came from Denmark, England, Finland, France, Germany, Ireland, Italy, Netherlands, Scotland, Spain and Switzerland. Survey data analysis suggests that (a) per diem rates have similar compositions in LERU and US programs, with >50% of the rates dedicated to recovering salary and fringe, followed by supplies (∼25%), facility costs (∼10%) and other expenses (∼15%); (b) ∼60% of US and LERU programs under-recover mouse care costs; (c) on average, LERU programs have a small positive net-operating balance, while US programs average a large deficit; (d) in LERU programs <50% of institutions fund the animal program deficit, while in US programs almost 100% of such deficits are covered by the institution; and (e) when setting per diem rates, both US and LERU programs rank cost accounting as the most influential factor. Both US and LERU programs are reluctant to raise per diem rates to the extent required to recover costs and, thus, continue to under-recover costs, resulting in the animal program being 'caught in the middle' between the competing financial challenges of investigator 'affordability' and the animal program's fiduciary responsibility to the institution.

Rapid ammonia build-up in small individually ventilated mouse cages cannot be overcome by adjusting the amount of bedding.

We sought to investigate if varying levels of bedding had an effect on intra-cage ammonia levels in individually ventilated mouse cages (Euro Standard Types II and III). Employing a routine 2 week cage-changing interval, our goal is to keep ammonia levels under 50 ppm. In smaller cages used for breeding or for housing more than four mice, we measured problematic levels of intra-cage ammonia, and a considerable proportion of these cages had ammonia levels at more than 50 ppm toward the end of the cage-change cycle. These levels were not reduced significantly when the levels of absorbent wood chip bedding was either increased or decreased by 50%. The mice in both cage types II and III were housed at comparable stocking densities, yet ammonia levels in larger cages remained lower. This finding highlights the role of cage volume, as opposed to simply the floor space, in controlling air quality. With the current introduction of newer cage designs that employ an even smaller headspace, our study urges caution. With individually ventilated cages, problems with intra-cage ammonia may go undetected, and we may opt to utilize insufficient cage-changing intervals. Few modern cages have been designed to account for the amounts and types of enrichment that are used (and, in parts of the world, mandated) today, adding to the problems associated with decreasing cage volumes.

Fast IMAC purification of non-tagged S100A8/A9 (calprotectin) from Homo sapiens and Sus scrofa.

S100A8/A9 (calprotectin) is a damage-associated molecular pattern molecule (DAMP) that plays a key role in the innate immune response of mammalia. S100A8/A9 is therefore widely used as a biomarker in human and veterinary medicine, but diagnostic tools for the detection of S100A8/A9 are rarely optimised for the specific organism, since the corresponding S100A8/A9 is often not available. There is need for an easy, reliable protocol for the production of recombinant, highly pure S100A8/A9 from various mammalia. Here we describe the expression and purification of recombinant human and porcine S100A8/A9 by immobilized metal affinity chromatography (IMAC), which takes advantage of the intrinsic, high-affinity binding of native un-tagged S100A8/A9 to metal ions. Highly pure S100A8/A9 is obtained by a combination of IMAC, ion exchange and size exclusion chromatographic steps. Considering the high sequence homology and conservation of the metal ion coordinating residues of S100A8/A9 metal binding sites, the protocol is presumably applicable to S100A8/A9 of various mammalia.

Effects of Multimodal Therapy, Blinding, and Multi-laboratory Protocol Conduct on the Robustness of the Rat Model of Adjuvant Induced Arthritis.

BACKGROUND/AIM: The aim of this study was to investigate the effects of multimodal therapy comprising buprenorphine (BUP) and indomethacin (IND) on key translational parameters in the rat adjuvant induced arthritis (AIA) model. Furthermore, we investigated the difference between visual assessment scores and histology scores generated by blinded and non-blinded assessors and the robustness and generalizability of results by conducting a multi-laboratory study. MATERIALS AND METHODS: The experiment was terminated on day 26 after 11 days (days 15-25) of voluntarily ingested buprenorphine and 7 days of gavage delivered indomethacin treatment (days 19-25). The treatment effects were assessed on the last day of the study, relying on body weight assessment, serum concentrations of α1- acid glycoprotein, and assessment of affected hind paws swelling, in-life and post mortem. RESULTS: Across two laboratories, the combined analgesic treatments had minimal effects on the measured model parameters indicating that multimodal treatment did not affect the translatability of the model. We found an improvement in clinical scores (a negative change in scores) in nearly all medicated animals when scored informed, whereas it was essentially 50:50 for the blinded scorings and no difference between the blinded and informed histological scoring. CONCLUSION: The present results support the use of more effective analgesic treatment regimens and the good practice recommendations advocating blinding as a mandatory practice in conduct of preclinical in vivo efficacy studies. In spite of minor differences between results obtained at the two sites, there was good agreement between them indicating robustness of the AIA model.

Effects of Transdermal Fentanyl Treatment on Acute Pain and Inflammation in Rats with Adjuvant-induced Monoarthritis.

Eliminating unnecessary pain is an important requirement of performing animal experimentation, including reducing and controlling pain of animals used in pain research. The goal of this study was to refine an adjuvant-induced monoarthritis model in rats by providing analgesia with a transdermal fentanyl solution (TFS). Male and female Sprague-Dawley rats, single- or pair-housed, were injected with 20 µL of complete Freund adjuvant (CFA) into the left ankle joint. CFA-injected rats treated with a single dose of transdermal fentanyl solution (0.33 or 1 mg/kg) were compared with an untreated CFA-injected group and sham groups that received either no treatment or TFS treatment (1 mg/kg) during 72 h. At the tested doses, TFS reduced mechanical hyperalgesia and improved the mobility, stance, rearing, and lameness scores at 6 h after CFA injection. Joint circumferences were not reduced by TFS treatment, and no significant differences were detected between the 2 doses of TFS, or between single- and pair-housed rats. Treatment with TFS did not appear to interfere with model development and characteristics. However, overall, the analgesic effect was transient, and several opioid-related side effects were observed.

Antidepressant Fluoxetine Does Not Appear to Interfere With Key Translational Parameters in the Rat Adjuvant-induced Arthritis Model.

BACKGROUND/AIM: This study aimed to investigate the analgesic effects of fluoxetine on Lewis rats of both sexes in the adjuvant-induced arthritis (AIA) rat model. In humans, chronic pain syndromes typical of rheumatoid arthritis (RA) co-exist with depression which is often treated with fluoxetine antidepressant known to have antinociceptive effects. MATERIALS AND METHODS: The experiment was terminated on day 26, after seven days of oral treatment (days 19-25) with fluoxetine and indomethacin. The effects of treatments were assessed on the final day of the study through measuring body weight, serum concentrations of a1-acid glycoprotein, visual arthritis assessment and post mortem histopathology assessment. RESULTS: Statistically significant difference was determined in the body weight of male subjects, with indomethacin-treated animals putting on significantly more weight than the vehicle and fluoxetine-treated counterparts. No differences were found between the different treatment groups in other study assessments. CONCLUSION: The present study did not provide support for analgesic effects of fluoxetine aimed at reducing the severity of the AIA model.

Acquired Clinical Immunity to Malaria in Nonhuman Primates Coinfected with Schistosoma and Plasmodium Parasites.

Naturally acquired immunity to malaria develops over several years and can be compromised by concomitant infections. This study explored the influence of chronic schistosomiasis on clinical outcome and immunity to repeated malaria infection. Two groups of baboons (n = 8 each), were infected with Schistosoma mansoni cercariae to establish chronic infections. One of the two groups was treated with praziquantel (PZQ) to eliminate schistosome infection. The two groups plus a new malaria control group (n = 8) were inoculated three times with Plasmodium knowlesi parasites at 1-month intervals. Clinical data and IgG, IgG1, memory T-cell, and monocyte levels were recorded. After three P. knowlesi infections, we observed (i) reduced clinical symptoms in all groups with each subsequent infection, (ii) increased IgG and IgG1 levels in the malaria control (Pk-only) group, (iii) increased IgG, IgG1, CD14+, and CD14- CD16+ levels in the Schistosoma-treated (Schisto/PZQ+Pk) group, and (iv) significantly lower IgG and IgG1 levels compared to those of the Pk-only group, reduced CD4+ CD45RO+ levels, and increased levels of CD14- CD16+ cells in the coinfected (Schisto+Pk) group. Chronic S. mansoni infection does not compromise establishment of clinical immunity after multiple malaria infections, with nonclassical monocytes seeming to play a role. Failure to develop robust antibody and memory T cells may have a long-term impact on acquired immunity to malaria infection.

Age-related cognitive impairment is associated with low serum concentrations of testosterone and CSF levels of amyloid beta 42 in male cynomolgus monkeys (Macaca fascicularis).

Aged memory-impaired cynomolgus monkeys had significantly lower levels of cerebrospinal amyloid (Aß42 ) and serum testosterone compared with young animals and non-memory-impaired controls. Our findings confirm similar findings in the human and substantiate the usefulness of the cynomolgus monkey as a spontaneous model for aging-associated senile dementia of the Alzheimer type.

Increased expression of GAPDH in cynomolgus monkeys with spontaneous cognitive decline and amyloidopathy reminiscent of an Alzheimer's-type disease is reflected in the circulation.

Previous studies of aging cynomolgus monkeys from our group identified spontaneous age-associated cognitive declines associated with biomarkers and brain lesions reminiscent of Alzheimer's Disease (AD), in a proportion of aged monkeys. However, the molecular mechanisms that underlie the spontaneous amyloid disorders and cognitive declines observed in these affected monkeys have yet to be investigated in detail. Using reverse transcriptase quantitative real time PCR techniques, normalized to the ACTB housekeeping gene, we analyzed the expression patterns of a number of genes which have been implicated in amyloid and tau abnormalities, in well-characterized aged cynomolgus monkeys with cognitive decline. A significantly increased expression of the genes coding for glyceraldehyde 3-phosphate dehydrogenase (GAPDH), was found in aged-cognitive decline monkeys compared to age-matched healthy controls. GAPDH has been implicated in several neurodegenerative diseases and interacts with beta amyloid precursor proteins. These findings provide support for the utilization of cynomolgus macaques in translational preclinical research as valid spontaneous models in experimental investigations of the relationships among aging, cognitive decline, and the neuropathy of AD.

Differences in Behavior Between Elderly and Nonelderly Captive Chimpanzees and the Effects of the Social Environment.

The population of NIH-owned or NIH-supported captive research chimpanzees is quickly becoming aged, and the 1998 NIH breeding moratorium has resulted in a skewed age distribution. As such, behavioral management programs aimed at refining the care of an aging captive chimpanzee population have become increasingly important. However, little research exists that addresses the ways in which captive chimpanzee behavior differs as a function of the interaction of age and aspects of the captive environment. We examined overall differences in behavior between elderly (35 y and older) and nonelderly (younger than 35 y) captive chimpanzees. Elderly chimpanzees exhibited significantly more rough scratching (a behavioral indicator of anxiety) and inactivity, less behavioral diversity, and less affiliation than their nonelderly counterparts. We also assessed whether elderly chimpanzee behavior and wounding rates differed as a function of housing in geriatric (group average age, 35 y or older) or nongeriatric (group average age, younger than 35 y) groups. In our program, geriatric social groups were characterized by smaller group size, more females within the group, and higher levels of individual mobility impairment compared with nongeriatric groups. Furthermore, elderly chimpanzees housed in geriatric groups displayed significantly increased rough scratching, decreased locomotion and submission than nongeriatric animals but no difference in wounding. These findings suggest that housing elderly chimpanzees in nongeriatric groups may be beneficial, given that doing so may stimulate locomotion. However, the establishment and maintenance of geriatric groups may be unavoidable as the demographics of the population of captive former research chimpanzees continues to age. Therefore, refinements to captive geriatric care strategies for chimpanzees should focus on methods of evaluating and enhancing functionally appropriate captive environments within geriatric groups.

Relationships between captive chimpanzee (Pan troglodytes) welfare and voluntary participation in behavioural studies.

Voluntary participation in behavioural studies offers several scientific, management, and welfare benefits to non-human primates (NHPs). Aside from the scientific benefit of increased understanding of NHP cognition, sociality, and behaviour derived from noninvasive behavioural studies, participation itself has the potential to provide functional simulations of natural behaviours, enrichment opportunities, and increased control over the captive environment, all of which enhance welfare. Despite a developing consensus that voluntary participation offers these welfare enhancements, little research has empirically investigated the ways that participation in behavioural studies may affect welfare. In the current study, we investigated potential relationships between captive chimpanzee welfare and long-term, repeated voluntary participation in noninvasive behavioural studies. We collected behavioural data on 118 chimpanzees at the National Center for Chimpanzee Care (NCCC) in Bastrop, Texas, USA between 2016 and 2018 using 15-minute focal animal samples. Additionally, we collected information on 41 behavioural studies conducted between 2010 and 2018 with the NCCC chimpanzees that involved exposure to a stimulus or manipulation. The total number of behavioural studies in which chimpanzees had participated over the approximately eight-year period was then examined in relation to levels of behavioural diversity, abnormal behaviour, rough scratching, inactivity, and locomotion using a series of regression analyses that controlled for rearing status and age of the chimpanzee at the time of data collection. Analyses revealed significant, positive relationships between the total number of studies in which chimpanzees participated and 1) behavioural diversity scores, R2 adj = .21, F(3,114) = 11.25, p < 0.001; and 2) rough scratching, R2 adj = .11, F(3,114) = 6.01, p = 0.001. The positive relationship between behavioural diversity scores and the total number of studies in which chimpanzees participated seems unsurprising, although we cannot draw conclusions about the directionality of this relationship. The result that rough scratching and the total number of studies in which chimpanzees participated were positively correlated is unexpected. However, rough scratching made up less than 1% of all activity in the current study, and as such, this result may not be biologically meaningful. These findings suggest that participation in behavioural studies is not likely to be detrimental to chimpanzee well-being, and may even be beneficial. Data such as these, which empirically investigate existing recommendations can help inform decisions pertaining to the participation of chimpanzees in behavioural research.

Clinical, Physiologic, and Behavioral Evaluation of Permanently Catheterized NMRI Mice.

Vascular catheterization is becoming a popular technique in laboratory rodents, facilitating repetitive blood sampling and infusion in individual animals. In mice, catheterization is complicated by their small body size, which may increase the risk of postoperative complications that may both threaten catheter longevity and animal welfare. Less obvious complications to a permanent catheter may include subclinical infection, visceral tissue damage from disseminating microthrombi released from the catheter, and distress from being isolated from conspecifics and other experimental stressors. Such complications may go unnoticed and may affect animal welfare as well as confound research outcomes. This study investigated the implications of long-term arterial catheterization in NMRI mice by evaluating clinical, physiologic and behavioral parameters. Body weight and food and water consumptions were monitored during the study period. Fecal corticosterone metabolites were quantified as biomarkers of stress, and nucleic acid metabolites (8-oxo-7,8-dihydro-2'-deoxyguanisine and 8-oxo-7,8-dihydroguanosine) as biomarkers of oxidative damage. Behavioral dysfunction was studied by scoring animal welfare and nest building. Catheters were placed the right common carotid artery of mice; catheterized mice were compared with sham-operated and nonsurgical control mice. Except for an increase in the body weight of catheterized mice during the experimental period, clinical parameters (body weight and food and water consumptions) did not differ between groups. Physiologic parameters (oxidized nucleic acid metabolites and fecal corticosterone metabolites) were higher in control mice during the first week of experimentation compared with the end of study but did not differ between groups. Likewise, catheterization had no effect on behavioral parameters (nest building and animal welfare assessment). Long-term arterial catheterization of mice had no detectable implications on animal welfare in this study.

Granulovacuolar Degeneration in Brains of Senile Cynomolgus Monkeys.

Neurons with histopathological changes consistent with granulovacuolar degeneration (GVD) were found in brain sections from aged cynomolgus monkeys (Macaca fascicularis) with clinical and pathological signs of cognitive aging. To our knowledge, this is the first reported description of GVD in non-human primates. GVD-like lesions were found also in age-matched cognitively healthy subjects, albeit in lower numbers, suggesting that they may relate to aging and the increase may have tendency to increase with the memory deficits. The increased incidence of GVD-like lesions in memory-impaired subjects with pahological backgrounds of senile plaques (SPs) and tauopathy is, however, an interesting observation of relevance to the characterization of pathologies in the spontaneous cynomolgus monkey model of human Alzheimer's type of brain pathology.

Does group size matter? Captive chimpanzee (Pan troglodytes) behavior as a function of group size and composition.

The National Institutes of Health and the Association of Zoos and Aquariums recommend that captive chimpanzees be housed in multi-male, multi-female, age-diverse groups of no less than seven individuals. These recommendations are rooted in the idea that captive chimpanzee groups should be modeled after free-ranging, wild, fission-fusion chimpanzee societies. However, captive chimpanzees do not face the environmental pressures faced by wild chimpanzees, including food scarcity, inter-group competition, and predation. As such, it has been posited that wild, natural conditions may not be the most relevant metric for defining optimal captive chimpanzee group sizes and compositions. Additionally, captive housing poses a set of restrictions on group sizes and compositions, including the need to balance large, multi-male groups with space per animal limitations and intra-group aggression. In the present study, we examined the behavioral effects of group size, within-group age range, and percentage of males in the group. We collected 713 hr of focal animal samples across 120 captive chimpanzees housed in social groups of 4-10 individuals using a 58-behavior ethogram. Chimpanzees housed in groups with a large age range exhibited less inactivity and more locomotion than chimpanzees housed in groups with smaller age ranges. Additionally, chimpanzees in groups of ≥7 with less than half males showed the highest levels of locomotion. Lastly, chimpanzees in groups of ≥7 with at least half males showed the highest levels of affiliation. There were no other significant differences in behavior as a function of these variables or their interactions. These findings lend some support to the existing group size and composition recommendations, providing empirical evidence that there may be certain advantages to housing captive chimpanzees in larger groups with a more diverse age range and/or more males. These results also have practical implications for behavioral management programs across captive settings.

Captive chimpanzee (Pan troglodytes) behavior as a function of space per animal and enclosure type.

Space per animal, or animal density, and enclosure type are important elements of functionally appropriate captive environments (FACEs) for chimpanzees. The National Institutes of Health (NIH) recommends that captive chimpanzees be maintained in areas of >250 ft2 /animal. Several studies have investigated chimpanzee behavior in relation to space per animal, but only two studies have examined these variables while attempting to hold environmental complexity constant. Both have found few, if any, significant differences in behavior associated with increased space per animal. The NIH does not provide recommendations pertaining to enclosure type. Although Primadomes™ and corrals are considered acceptable FACE housing, no studies have investigated chimpanzee behavior in relation to these two common types of enclosures. We examined the NIH space per animal recommendation, and the effects of enclosure type, while maintaining similar levels of environmental complexity. We used focal animal observations to record the behavior of 22 chimpanzees in three social groups following within-facility housing transfers. Chimpanzees that were moved from an area with space below the NIH recommendation to the same type of enclosure with space above the recommendation (dome to double dome) exhibited significantly more locomotion and behavioral diversity post-transfer. Chimpanzees that were moved from an area with space below the recommendation to a different type of enclosure with space above the recommendation (dome to corral) exhibited significant increases in foraging and behavioral diversity, and a decrease in rough scratching. Lastly, chimpanzees that were moved from an area above the recommendation to a different enclosure type with space equal to the recommendation (corral to double dome) exhibited an increase in behavioral diversity. These results add to the body of literature that addresses the concept of specific minimum space requirements per chimpanzee, and highlight the need for more empirical investigation of the relationship between space per chimpanzee, behavior, and welfare.

Ultrasonographic and histological evaluation of the effects of long-term carotid catheterization on cardiac function in NMRI mice.

Catheterization of laboratory mice is commonly performed in biomedical research to infuse substances and for blood sampling. One approach is to catheterize the right common carotid artery and advance the catheter until the tip is positioned in the aorta or the proximal brachiocephalic trunk. Owing to the small body size of the mouse, a catheter tends to occupy a great part of even the larger vessel lumens, and this may increase vascular resistance with potential pathophysiological impacts on the heart. The present study compared cardiac function of catheterized mice, with catheter tip placement in the brachiocephalic trunk, with sham-operated mice and non-operated control mice. During four weeks post-catheterization, M-mode echocardiography measurements of the thickness of the left ventricular anterior wall, left ventricular inner diameter and the thickness of the left ventricular posterior wall were performed. The left ventricular volume, ejection fraction and fractional shortening were calculated. Moreover, aortic recordings of the thickness of the medial and lateral walls as well as the inner diameter were measured. Terminally, histological analysis of the hearts was conducted, and body weights and heart weights were compared between groups. No effects on echocardiography parameters, histology, body weights or cardiac weights could be found between groups. In the present study, implantation of a carotid catheter with catheter tip placement in the proximal brachiocephalic trunk had minimal influence on cardiac and aortic physiology and did not induce significant cardiac changes.