Investigation of Various Intramuscular Volumes Delivered to the Semimembranosus Muscle of Cavia porcellus.

The goal of this study is to provide quantitative data on the ideal volume for intramuscular (IM) injections into the semimembranosus muscle of guinea pigs weighing between 320 to 410 grams. This evaluation comprised 2 experiments. The first was to assess dispersion leakage of intramuscularly injected iohexol, a radiocontrast agent commonly used in Computed Tomography (CT), based on analysis of in vivo imaging. The second used varying volumes of intramuscularly injected sodium chloride (0.9% NaCl) to assess pain and pathology associated with IM injection. Hartley guinea pigs were injected IM with varying volumes of either iohexol or sodium chloride (150, 300, 500, 1000 and 1500 µL). In the iohexol experiment, results suggest IM volumes of 150 and 300 µL remain within the target muscle. In the experiment using sodium chloride, pain and pathology did not increase as IM volume increased. The pathology noted was related to needle tract through the musculature rather than the volume size of the injectate. The results did not reveal a correlation between volume of IM 0.9% NaCl and pain levels. We conclude that volume size correlates more with precision and accuracy of delivery into the intended muscle tissue. Regarding tissue distribution, our findings also suggest that the optimal capacity for IM injection in the semimembranosus muscle should be less than 500 µL.

Evaluation of Volume of Intramuscular Injection into the Caudal Thigh Muscles of Female and Male BALB/c Mice (Mus musculus).

This study presents recommendations for intramuscular injection into the caudal thigh muscle of mice according to analysis of in vivo imaging of intramuscularly injected iohexol, a radiocontrast agent commonly used in CT imaging. An experienced laboratory animal technician using a Hamilton syringe intramuscularly injected iohexol into isoflurane-anesthetized female and male BALB/c mice. Injected volumes (25, 50, 100, and 200 µL) underwent CT scanning at 9 time points over a 3-h period. The distribution of the injectate in the muscles of the rear leg was examined over time for each volume group. Results indicated that 25- and 50-µL volumes remain intramuscularly. At 100 µL, mild to moderate leakage into the extramuscular tissues occurred. At 200 µL, leakage into the extramuscular tissues was moderate to severe. Our results suggest volumes of 50 µL or less are recommended for the caudal thigh muscles of mice when intramuscular pharmacokinetics are needed; volumes greater than 50 µL display variable distribution into extramuscular tissues, thus potentially yielding different pharmacokinetic profiles.

Comparison of Saliva Collection Methods for the Determination of Salivary Cortisol Levels in Rhesus Macaques (Macaca mulatta), Cynomolgus Macaques (Macaca fascicularis), and African Green Monkeys (Chlorocebus aethiops).

The ability to quickly and accurately determine cortisol as a biomarker for stress is a valuable tool in assessing the wellbeing of NHP. In this study, 2 methods of collecting saliva (a commercial collection device and passive drool) and the resulting free salivary cortisol levels were compared with total serum cortisol concentration in rhesus macaques (Macaca mulatta), cynomolgus macaques (Macaca fascicularis) and African green monkeys (Chlorocebus aethiops) at 2 collection time points. Serum and salivary cortisol levels were determined using a competitive quantitative ELISA. In addition, both saliva collection methods were evaluated for volume collected and ease of use. Compared with passive drool, the experimental collection device was more reliable in collecting sufficient volumes of saliva, and the resulting salivary cortisol values demonstrated stronger correlation with serum cortisol concentration in all species and collection days except cynomolgus macaques on day 1. This saliva collection device allows quick and reliable sample collection for the determination of salivary cortisol levels. In addition, the results might provide a useful tool for evaluating hypothalamic-pituitary-adrenal axis activity or the physiologic stress reaction in NHP as well as a biomarker of psychologic stress states in a variety of situations.

Infection of mice with influenza A/WSN/33 (H1N1) virus alters alveolar type II cell phenotype.

Influenza viruses cause acute respiratory disease of great importance to public health. Alveolar type II (ATII) respiratory epithelial cells are central to normal lung function and are a site of influenza A virus replication in the distal lung. However, the consequences of infection for ATII cell function are poorly understood. To determine the impact of influenza infection on ATII cells we used C57BL/6-congenic SP-C(GFP) mice that express green fluorescent protein (GFP) under the control of the surfactant protein-C (SP-C) promoter, which is only active in ATII cells. Most cells isolated from the lungs of uninfected SP-C(GFP) mice were GFP(+) but did not express the alveolar type I (ATI) antigen podoplanin (PODO). ATII cells were also EpCAM(+) and α2,3-linked sialosaccharide(+). Infection with influenza A/WSN/33 virus caused severe hypoxemia and pulmonary edema. This was accompanied by loss of whole lung GFP fluorescence, reduced ATII cell yields, increased ATII cell apoptosis, reduced SP-C gene and protein expression in ATII cell lysates, and increased PODO gene and protein levels. Flow cytometry indicated that infection decreased GFP(+)/PODO(-) cells and increased GFP(-)/PODO(+) and GFP(-)/PODO(-) cells. Very few GFP(+)/PODO(+) cells were detectable. Finally, infection resulted in a significant decline in EpCAM expression by PODO(+) cells, but had limited effects on α2,3-linked sialosaccharides. Our findings indicate that influenza infection results in a progressive differentiation of ATII cells into ATI-like cells, possibly via an SP-C(-)/PODO(-) intermediate, to replace dying or dead ATI cells. However, impaired SP-C synthesis is likely to contribute significantly to reduced lung compliance in infected mice.

Comparative effectiveness of isolation techniques for contemporary Influenza A virus strains circulating in exhibition swine.

The current study sought to compare the effectiveness of 2 virus isolation methods for the recovery of contemporary Influenza A virus (FLUAV) strains circulating in swine at agricultural exhibitions. Following the emergence of the influenza A (H1N1)pdm09 virus, increased surveillance of FLUAV strains among swine was recommended for early detection of emerging strains that threaten animal and human health. The increase in genetic drift and genomic reassortment among FLUAV strains infecting swine since 1998 necessitates that detection protocols be periodically validated for contemporary FLUAV strains. During 2009, nasal swabs were collected from 221 clinically healthy pigs at 12 agricultural exhibitions in Ohio. Nasal swabs were tested in parallel for the presence of FLUAV strains using 3 methodologies: 2 passages through Madin-Darby canine kidney (MDCK) cells adapted to serum-free medium (SFM), 2 passages through embryonated chicken eggs (ECEs), and real-time reverse transcription polymerase chain reaction (real-time RT-PCR). Of the 221 samples, 40 (18.1%) were positive for FLUAV recovery in MDCK cell culture and 13 (5.9%) were positive in ECEs (P = 0.015). All samples positive in ECEs were also positive in MDCK cell culture. MDCK cell culture virus isolation results were in perfect agreement with results of the real-time RT-PCR. Hemagglutinin and neuraminidase combinations of the recovered isolates were H1N2 and H3N2, which were consistent with FLUAV strains circulating in U.S. pigs. Effectiveness and cost savings justify the use of SFM-adapted MDCK cell culture over ECEs for the recovery of contemporary FLUAV strains from exhibition swine.