Mice are used extensively in transplantation studies involving bone marrow ablation. Due to the increasing security issues and expenses involved with γ irradiators, self-contained X-ray irradiators have been increasing in popularity. We hypothesized that bone marrow ablation by irradiation of mice with a ¹³⁷Cs irradiator would be comparable to that from an X-ray source irradiator. A lethal-dose curve was obtained by irradiating C57BL/6J mice with 500, 700, 900, and 1100 cGy from either source. These data were used to determine the lethal radiation exposure range for a noncompetitive bone marrow engraftment curve for each source. At 90 d after reconstitution, the bone marrow engraftment curves revealed significant differences between the 2 sources in the establishment of B cell, myeloid, and T cell lineages. Murine B cell reconstitution after exposure to a ¹³⁷Cs source was greater than that after X-ray exposure at each dose level, whereas the converse was true for myeloid cell reconstitution. At the 1050- and 1100-cGy doses, mice irradiated by using the X-ray source demonstrated higher levels of T cell reconstitution but decreased survival compared with mice irradiated with the ¹³⁷Cs source. We concluded that although both sources ablated endogenous bone marrow sufficiently to enable stem cell engraftment, there are distinct physiologic responses that should be considered when choosing the optimal source for use in a study and that irradiation from the ¹³⁷Cs source was associated with lower overall morbidity due to opportunistic infection.

Many chronic diseases are associated with both fatigue and disrupted or nonrestorative sleep. In addition, so-called 'sickness behaviors' (for example, anorexia, anhedonia, reduced social interaction, fatigue) are common during infectious and inflammatory disease and have been linked to facets of the immune response. To study these relationships, we used murine gammaherpesvirus (MuGHV), a natural pathogen of wild rodents that provides an experimental model for studying the pathophysiology of an Epstein-Barr (EBV)-like γ-herpesvirus infection in mice. We exposed male and female C57BL/6J mice that were either uninfected or latently infected with MuGHV to either sleep fragmentation (SF) or control conditions and measured the effects on behavior and markers of inflammation. Exposure of infected male mice to SF during the normal somnolent (light) phase significantly reduced locomotor activity during the subsequent active phase, despite an intervening 6-h rest period. Infection was associated with significant increases in lung IFNγ and CXC motif ligand (CXCL) 10 in both male and female mice. In both infected and uninfected male mice, exposure to SF was associated with lower levels of IL1β and C-C motif ligand (CCL) 3 in lung. Exposure of infected female mice to SF led to reductions in lung IL2, CXCL1, and CCL 3. Thus, compared with control conditions, SF was generally associated with lower concentrations of various cytokines in lung. These findings, together with our previous work, indicate that complex interactions among several host factors likely contribute to the behavioral and inflammatory changes associated with viral infection and sleep disruption even in a well-controlled mouse model.

During 1 year, experimentally naïve C57BL/6NCrl weanlings born to timed-pregnant dams from a single vendor demonstrated markedly increased mortality associated with runting, abnormal gait, and decreased activity. Gram-positive, aerobic, α-hemolytic, coccoid bacteria were isolated from the meninges (n = 16), blood (n = 1), and kidneys (n = 1) of clinically affected weanlings (n = 15); from the uterus (n = 1), meninges (n = 1), and oral cavity (n = 2) of 3 dams; and from the meninges and oral cavity of a clinically affected 86-d-old mouse in the same colony. Multifocal, necrosuppurative meningoencephalitis and ventriculitis with intralesional gram-positive coccoid bacteria were present in all but 2 affected animals. The bacterium also was isolated from the oral cavity of an asymptomatic timed-pregnant dam (1 of 23) from the same vendor and from 8 mice at the vendor's facility. All isolates (n = 25) were identified by using 2 semiautomated rapid-identification systems, one of which consistently identified the causative bacterium as Aerococcus viridans 2 (n = 12) or 3 (n = 13), with probabilities of 55.7% to 98.3%. The bacterium did not grow in 6.5% NaCl at 10 °C, thus suggesting a Streptococcus species. Partial 16S rRNA sequencing of 4 isolates suggested S. hyointestinalis (probability, 93.4%) and S. gallinaceus (99.5%). Full 16S rRNA sequences for 3 isolates identified the bacterium as a novel Streptococcus species most closely related to S. acidominimus strain LGM (96.5%) and Streptococcus species strain Smarlab 3301444 (96.3%) and for which we propose the name S. azizii.

Although several methods for determining erythrocyte lifespan are used in research studies that involve mice, all involve the alteration of RBC to allow for its tracking over time, which may affect overall RBC survival. The aims of this study were to determine 1) whether sex affects RBC survival; 2) whether RBC survival differs between the biotin method and an alternative method that uses GFP; and 3) whether repeat exposure of mice to biotin results in an antibiotin antibody response or decreased RBC survival. The results suggest no difference in the RBC half-life between male and female C57BL/6 mice (22.9 ± 1.2 and 22.4 ± 0.9 d, respectively). In addition, RBC half-life did not differ between the biotin- and GFP-based methods (20.5 ± 2.1 d and 22.7 ± 2.1 d, respectively). Finally, retransfusion of mice 90 d after an initial transfusion with biotin-labeled RBC did not induce detectable antibiotin antibodies nor alter the half-life of transfused biotin-labeled RBC (initial transfusion, 22.0 ± 1.2 d; subsequent transfusion, 23.4 ± 1.4 d, respectively).

Despite the great value of diagnostic bloodwork for identifying disease in animals, the volume of blood required for these analyses limits its use in laboratory mice, particularly when they are clinically ill. We sought to determine the effects of acute blood loss (ABL) following blood collection for diagnostic bloodwork in healthy mice compared with streptozotocin-induced diabetic and dextran sulfate sodium (DSS)-treated dehydrated mice. ABL caused several mild changes in the control mice, with significant decreases in body weight, temperature, and activity in both experimental groups; increased dehydration and azotemia in the DSS-treated mice; and a significant drop in the blood pressure of the diabetic mice. To determine whether these negative outcomes could be ameliorated, we treated mice with intraperitoneal lactated Ringers solution either immediately after or 30 min before ABL. Notably, preABL administration of fluids helped prevent the worsening of the dehydration and azotemia in the DSS-treated mice and the changes in blood pressure in the diabetic mice. However, fluid administration provided no benefit in control of blood pressure when administered after ABL in the diabetic mice. Furthermore, fluid therapy did not prevent ABL-induced drops in body weight and activity. Although one mouse not receiving fluid therapy became moribund at the 24-h time point, no animals died during the 24-h study. This investigation demonstrates that blood for diagnostic bloodwork can be collected safely from clinically ill mice and that preemptive fluid therapy mitigates some of the negative changes associated with this blood loss.

Pulmonary arterial hypertension (PAH) is a devastating disorder characterized by progressive elevation of the pulmonary pressures that, in the absence of therapy, results in chronic right-heart failure and premature death. The vascular pathology of PAH is characterized by progressive loss of small (diameter, less than 50 μm) peripheral pulmonary arteries along with abnormal medial thickening, neointimal formation, and intraluminal narrowing of the remaining pulmonary arteries. Vascular pathology correlates with disease severity, given that hemodynamic effects and disease outcomes are worse in patients with advanced compared with lower-grade lesions. Novel imaging tools are urgently needed that demonstrate the extent of vascular remodeling in PAH patients during diagnosis and treatment monitoring. Optical coherence tomography (OCT) is a catheter-based intravascular imaging technique used to obtain high-resolution 2D and 3D cross-sectional images of coronary arteries, thus revealing the extent of vascular wall pathology due to diseases such as atherosclerosis and in-stent restenosis; its utility as a diagnostic tool in the assessment of the pulmonary circulation is unknown. Here we show that OCT provides high-definition images that capture the morphology of pulmonary arterial walls in explanted human lungs and during pulmonary arterial catheterization of an adult pig. We conclude that OCT may facilitate the evaluation of patients with PAH by disclosing the degree of wall remodeling present in pulmonary vessels. Future studies are warranted to determine whether this information complements the hemodynamic and functional assessments routinely performed in PAH patients, facilitates treatment selection, and improves estimates of prognosis and outcome.

Measuring tidal volume (V_T) in nonintubated swine or swine with leaking breathing circuits is challenging. The aim of this study was to validate respiratory inductance plethysmography (RIP) for measuring V_T in swine that are comparable in size to adult humans. To determine calibration curves, V_T and RIP readings were obtained from anesthetized swine (n = 8; weight, 46–50 kg) during positive-pressure (mechanical) ventilation and spontaneous breathing. For positive-pressure ventilation, 6 pigs were mechanically ventilated by using the pressure-control mode. The 2 pigs in the spontaneously breathing cohort each received a single intravenous bolus dose of propofol to abolish spontaneous breathing; V_T was measured during gradual return of their respiratory drive. A flow–volume sensor was placed between the proximal end of the endotracheal tube and breathing circuit for the recording of inspiratory and expiratory V_T. RIP readings were recorded by using 2 bands, which simultaneously measured ribcage and abdominal excursions. The data revealed that V_T was linearly correlated with the movements of both ribcage and abdomen as measured by using plethysmography over a large range of tidal volume (44 to 1065 mL). In addition, the intercept of the linear equation was small or even negative during spontaneous breathing but increased significantly (maximum, 145 mL, 59.2 ± 35.1 mL) during positive pressure ventilation. Our results indicate that V_T in swine can be calculated by using a simple univariate linear regression equation with RIP readings obtained during either mechanical ventilation or spontaneous breathing.

Nonhuman primates are the experimental animals of choice for the study of many human diseases. As such, it is important to understand that endemic viruses of primates can potentially affect the design, methods, and results of biomedical studies designed to model human disease. Here we review the viruses known to be endemic in squirrel monkeys (Saimiri spp.). The pathogenic potential of these viruses in squirrel monkeys that undergo experimental manipulation remains largely unexplored but may have implications regarding the use of squirrel monkeys in biomedical research.

Marburg virus outbreaks are sporadic, infrequent, brief, and relatively small in terms of numbers of subjects affected. In addition, outbreaks most likely will occur in remote regions where clinical trials are not feasible; therefore, definitive, well-controlled human efficacy studies to test the effectiveness of a drug or biologic product are not feasible. Healthy human volunteers cannot ethically be deliberately exposed to a lethal agent such as Marburg virus in order to test the efficacy of a therapy or preventive prior to licensure. When human efficacy studies are neither ethical nor feasible, the US Food and Drug Administration may grant marketing approval of a drug or biologic product under the 'Animal Rule,' through which demonstration of the efficacy of a product can be 'based on adequate and well-controlled animal efficacy studies when the results of those studies establish that the drug is reasonably likely to produce clinical benefit in humans.' This process requires that the pathogenic determinants of the disease in the animal model are similar to those that have been identified in humans. After reviewing primarily English-language, peer-reviewed journal articles, we here summarize the clinical manifestations of Marburg virus disease and the results of studies in NHP showing the characteristics and progression of the disease. We also include a detailed comparison of the characteristics of the human disease relative to those for NHP. This review reveals that the disease characteristics of Marburg virus disease are generally similar for humans and 3 NHP species: cynomolgus macaques (Macaca fascicularis), rhesus macaques (Macaca mulatta), and African green monkeys (Chlorocebus aethiops).

Osteoarthritis is associated with pain and immobility in both humans and animals. However, available resources for osteoarthritis management in captive NHP are limited. This case report describes a novel management strategy for a 10-y-old male macaque with unilateral hindlimb lameness, prominent muscle wasting, and severely limited range of motion. Radiographs of the affected limb showed lytic lesions of the femoral head. To relieve pain and improve mobility, femoral head and neck ostectomy (FHO) was performed, and multiple pharmacotherapies were initiated. The macaque also received a unique method of physical therapy that required no sedation, acted as enrichment, and was implemented by using a conventional caging system. The response to therapy was monitored by measuring thigh circumference in the operated and nonoperated limbs, which demonstrated improvement in both legs. The unique physical therapy in conjunction with surgery and pharmacotherapy benefited the macaque with osteoarthritis by reducing discomfort and improving mobility.

A 3.5-y-old, female rhesus macaque (Macaca mulatta) inoculated with SIVmac239 presented 8 mo later for inappetence and facial bruising. Physical examination revealed a superficial skin abrasion below the left eye, bruising below the left brow, and epistaxis of the left nostril. There were no significant findings on CBC, serum chemistry, urinalysis, or radiographs. Differential diagnoses included infectious etiologies, self-injurious behavior, immune-mediated dermatitis, and neoplasia. Lack of response to antibiotic and analgesic therapy and observations of the macaque made it apparent that the skin lesions were self-inflicted. The excoriations rapidly progressed to extend over the nose, and the left palpebrae became edematous. Euthanasia was elected because the macaque appeared to be experiencing continued discomfort despite analgesic therapy. Histopathologic examination revealed systemic cytomegalovirus (CMV) infection involving the facial nerves, periocular nerves, meninges, and perimesenteric lymph nodes. CMV is a common infection in macaques, with adult seroprevalence close to 100% in most colonies. Infection in immunocompetent animals is usually asymptomatic but can cause significant clinical disease in immunodeficient hosts. CMV is associated with a painful peripheral neuropathy in human AIDS patients, and analgesic treatment is often unsatisfactory. Peripheral neuropathy secondary to CMV should be considered as an underlying cause of self-injurious behavior in SIV-infected macaques. Macaques affected by other diseases and disorders may also be at risk for development of painful peripheral neuropathies.

A 4-y-old female cynomolgus macaque presented for veterinary evaluation prior to placement in a preclinical study showed markedly low platelet counts that continued to decrease over time. Physical examination over the next several days showed areas of pale red discoloration in forelimbs, anterior thorax, and inguinal area and multifocal pinpoint areas of erythema or scabs. An area of dark red discoloration approximately 2 cm in diameter on the dorsal surface of the tongue was discovered on day 9. The macaque was euthanized, and histopathologic evaluation showed multifocal, ulcerative or erosive, hemorrhagic, lymphohistiocytic and neutrophilic glossitis and tonsillitis. The lesions on the tongue were associated with opportunistic fungi consistent with Candida albicans. The bone marrow showed megakaryocytic hyperplasia. There was no evidence of increased consumption of platelets, sequestration of platelets, or bone marrow suppression. The monkey was serologically negative for simian retrovirus, SIV, and simian T-lymphotropic virus. In light of cases reported in humans, immune-mediated destruction of platelets due to autoantibodies secondary to Candida albicans infection was considered. However, we were unable to detect antiplatelet antibodies on the platelet surface or in serum to support this etiology; therefore idiopathic thrombocytopenia was diagnosed. To our knowledge, this case represents the second reported observation of acquired thrombocytopenia in a nonhuman primate and the first reported observation in a cynomolgus macaque.