Obstructive uropathy secondary to uterine leiomyoma in a chimpanzee (Pan troglodytes).

Complications due to uterine leiomyomata in chimpanzees have rarely been documented. Here we describe a female chimpanzee that developed severe hydronephrosis in the right kidney due to leiomyoma. Because hysterectomy did not alleviate the hydronephrosis, nephrectomy was elected. After these procedures, the chimpanzee is doing well. Leiomyomata screening programs with treatment algorithms are a useful component of a comprehensive chimpanzee program.

Challenge pools of hepatitis C virus genotypes 1-6 prototype strains: replication fitness and pathogenicity in chimpanzees and human liver-chimeric mouse models.

Chimpanzees represent the only animal model for studies of the natural history of hepatitis C virus (HCV). To generate virus stocks of important HCV variants, we infected chimpanzees with HCV strains of genotypes 1-6 and determined the infectivity titer of acute-phase plasma pools in additional animals. The courses of first- and second-passage infections were similar, with early appearance of viremia, HCV RNA titers of >10(4.7) IU/mL, and development of acute hepatitis; the chronicity rate was 56%. The challenge pools had titers of 10(3)-10(5) chimpanzee infectious doses/mL. Human liver-chimeric mice developed high-titer infections after inoculation with the challenge viruses of genotypes 1-6. Inoculation studies with different doses of the genotype 1b pool suggested that a relatively high virus dose is required to consistently infect chimeric mice. The challenge pools represent a unique resource for studies of HCV molecular virology and for studies of pathogenesis, protective immunity, and vaccine efficacy in vivo.

In vivo bone formation in silk fibroin and chitosan blend scaffolds via ectopically grafted periosteum as a cell source: a pilot study.

Reconstruction of a critical size bone defect in the head and neck after trauma or tumor resection remains challenging. While certain defects, such as isolated orbital floor fractures, may be reconstructed with alloplastic biomaterials, larger defects or those involving load bearing bones usually require autologous tissue reconstruction. Vascularized bone free flaps remain the gold standard for large bone defects of the head and neck. These are generally lengthy, complicated, multi-step procedures that require subspecialty expertise to assure optimal outcomes.1 Invariably any procedure where autologous bone is harvested carries with it donor site morbidity.2 To spare the patient this additional morbidity and avoid potential complications associated with the harvest of this tissue, an alternative source for bone that would be sufficient to fill a critical-sized defect is needed.

Use of vascularized periosteum or bone to improve healing of segmental allografts after tumor resection: an ovine rib model.

BACKGROUND: Despite technical advances, nonunion or delayed union remains an important clinical problem when segmental allografts are used to repair diaphyseal defects after bone tumor resection. Using an ovine rib model, the authors studied whether the addition of a vascularized periosteum or bone flap improved healing compared with a segmental allograft alone. METHODS: A 4-cm segment of rib was resected from four consecutive ribs of 15 sheep. Three different reconstructions were compared within the same sheep: allograft alone, allograft and vascularized periosteum, and allograft and vascularized bone. One defect was not reconstructed and served as a control. Five sheep were humanely killed at each of the following time points: 9, 12, and 15 weeks. The host-allograft junctions were analyzed using plain radiographs, micro-computed tomography, and histologic examination. RESULTS: Micro-computed tomographic analysis showed significant improvement with each reconstruction technique over time. Plain radiographs and histologic analyses demonstrated earlier bridging of the host-allograft junction when either vascularized periosteum or vascularized bone was used compared with allograft alone. CONCLUSION: Use of vascularized periosteum or bone may facilitate healing of the host-allograft junction after intercalary allograft reconstruction.

Sheep stromal-epithelial cell interactions and ovarian tumor progression.

Previous studies suggest that underlying ovarian stromal cues may regulate the ovarian surface epithelium. However, little is known about the interaction between ovarian stromal cells (OSC) and ovarian surface epithelial cells (OSE) under normal physiologic and pathologic conditions, largely because of the lack of a suitable model. In the current study, the OSC obtained from a sheep were immortalized with SV-40 T/t antigen (designated IOSC) and telomerase reverse transcriptase (designated IOSCH), followed by transfection with the oncogenic allele of the human H-Ras oncogene (designated IOSChR). IOSC cells transfected with H-Ras before immortalization with telomerase were designated IOSCRH. These sheep OSCs were used in both in vitro and in vivo model systems to evaluate mechanisms by which OSCs influence ovarian tumor progression. Normal sheep OSCs were found to inhibit the growth of SKOV3 and OVCAR3 human ovarian cancer cells, but not normal sheep OSE and human OSE cells (hOSE137 cells). In contrast, IOSChR and IOSCRH cells stimulated the growth of normal sheep and human OSE cells, as well as cancer cells. These findings were confirmed by in vivo studies. Our data provide compelling support for the importance of stromal-epithelial cell interactions during tumor progression, and show for the first time that immortalized and transformed OSCs promote growth of ovarian epithelial tumors.

Ovine model for engineering bone segments.

We propose a large animal model for bone tissue engineering that yields quantitative data and simulates clinical methods and tissue needs. Skeletally mature domestic sheep (n = 20) were each implanted with three rectangular (1 x 1 x 4 cm), hollow tissue-molding chambers that were empty (control) or filled with equal weights (6.71-6.78 g) of particulate autologous bone graft (MBG) or bone graft that was autoclaved to denature stored growth factors (DeMBG). MBG provided scaffold and bioactive factors, and DeMBG provided only scaffold. The chambers were enclosed on five sides and securely implanted so that the open face was apposed to the osteogenic (i.e., cambium) layer of the rib periosteum for 3, 6, 9, 12, or 24 weeks, after which the chambers were harvested and the contents analyzed. Each chamber contained osseous and fibrovascular tissue. MBG-containing chambers had the best maintenance of tissue volume compared with DeMBG-containing or empty chambers, but it still decreased steadily over time. Despite this, the MBG-containing chambers showed continuous active bone formation. There was increasing calcified tissue with penetration of osteogenesis up to a mean of 0.75 +/- 0.15 cm from the periosteum by 9 weeks, and the osteogenic area peaked at 0.59 +/- 0.13 cm2 by 12 weeks. Using quantitative measures that reflect clinical needs (i.e., tissue volume, shape, and quality), it was possible to distinguish differences in performance associated with manipulation of implanted scaffold and bioactive factors. This ovine model may serve as a useful tool to develop clinical osseous tissue-engineering strategies.

Safety of continuous intrathecal midazolam infusion in the sheep model.

UNLABELLED: We investigated the safety of midazolam administered by continuous intrathecal infusion in relevant animal models. Preservative-free midazolam was delivered to sheep and pigs by using implanted infusion systems (SynchroMed pumps plus silicone catheters). Sheep received midazolam 5 mg/d (n = 4) or 15 mg/d (n = 7) or saline (n = 2) for 43 days at 125 micro L/h. One sheep received 10 mg/d. Infusion concentrations ranged from 1.7 to 2.5 mg/mL (5 mg/d) and from 2.5 to 5.0 mg/mL (15 mg/d). Pigs were evaluated for toxicity only and received 15 mg/d (n = 2) or saline (n = 1) for 43 days at 125 micro L/h. Behavior, neurologic function, and vital signs were documented. Serum and cerebrospinal fluid chemistry and cytology were evaluated, and histology was performed on spinal cord tissue. Behavior and neurologic function remained normal in all subjects. Gross and microscopic evaluation of spinal tissue revealed mild inflammation surrounding the catheter tract in both the midazolam-treated and the saline-treated groups. This inflammation was likely attributable to the mechanical presence of the catheter. These data demonstrate that continuous intrathecal infusion of preservative-free midazolam at doses up to 15 mg/d were well tolerated. IMPLICATIONS: We investigated the toxicity of preservative-free intrathecal midazolam delivered continuously via implanted infusion systems in sheep and pigs. Doses of 5-15 mg/d were well tolerated. The lack of neurotoxicity observed suggests that intrathecal midazolam may be an alternative for the treatment of intractable pain that is unresponsive to opioids.

Continuous intrathecal infusion of hydromorphone: safety in the sheep model and clinical implications.

OBJECTIVE: To determine the safety of hydromorphone delivered by continuous intrathecal infusion via implanted delivery systems in sheep. DESIGN: Sheep implanted with intrathecal infusion systems were randomly assigned to receive either 1.5, 3, or 6 mg/day hydromorphone HCl or saline control (3 sheep/dose level) at a fixed infusion rate of 1.92 mL/day for 28-31 days. Infusions were initiated approximately 5 days after surgical implantation of the delivery systems (pumps and intrathecal catheters), and investigators were blinded to doses administered. An additional group of sheep (N=3) received hydromorphone (open label) at a dose of 12 mg/day. All animals were examined daily during drug infusion for changes in behavior and neurologic function. Cerebrospinal fluid was analyzed for protein, cytology, and hydromorphone concentration in samples collected prior to and at the end of drug infusion. The spinal cord with the catheter in situ was removed en bloc and fixed in formalin for microscopic analysis. RESULTS: All sheep receiving intrathecal hydromorphone exhibited gaiting deficits and biting behavior over the caudal lumbar area above the infusion site. Animals treated with 12 mg/day were sedate and lethargic, and exhibited repeated biting behavior over the caudal lumbar area during the study. No lesions were noted in any animal upon gross evaluation of the spinal cord. Microscopic changes were comparable between hydromorphone- and saline-treated animals with one exception. Mild inflammation 5 cm cranial to the catheter tip was present in two of three sheep receiving 12 mg/day and in one of three sheep receiving 1.5 mg/day. Mild chronic inflammation hydromorphone in the vicinity of the catheter was also presented in saline-treated animals. CONCLUSIONS: Hydromorphone was not associated with inflammatory mass formation in the sheep model. Further studies are necessary to determine whether hydromorphone is a safer alternative to morphine for continuous intrathecal infusion for the treatment of chronic pain.

Safety of chronic intrathecal morphine infusion in a sheep model.

BACKGROUND: The safety of chronically administered intrathecal morphine has been questioned. Therefore, the authors examined the behavioral and neurologic effects and neurotoxicity of continuous intrathecal morphine administration in sheep. METHODS: Groups of three sheep were implanted with intrathecal infusion systems for the continuous administration of morphine (3, 6, 9, 12, or 18 mg/day) or saline at a fixed infusion rate of 1.92 ml/day beginning approximately 7 days after implantation. Sheep were examined daily for any changes in behavior or neurologic function. After 28-30 days, the animals were humanely killed. Cerebrospinal fluid samples were collected and analyzed for protein, erythrocytes and leukocytes, and morphine content. The spinal cord and meninges with the catheter in situ was removed en bloc and fixed in formalin for histologic analysis. RESULTS: Unilateral hind-leg gait deficits were observed in two of three animals in each of the 12- and 18-mg/day dose groups. Gross and microscopic evaluation of spinal cord tissue from these animals revealed intradural-extramedullary inflammatory masses that compressed the spinal cord at the catheter-tip and mid-catheter areas. This inflammation was ipsilateral to extremities that exhibited gait deficits and had acute and chronic cellular components. CONCLUSIONS: The toxicity of intrathecal morphine seems to be dependent on the amount of morphine infused, although the effects of dose versus concentration cannot be clearly distinguished in this study. Intrathecal morphine doses of 12- 18 mg/day produced inflammatory masses extending from the catheter tip down the length of the catheter within the subarachnoid space. Doses of 6-9 mg/day produced mild-to-moderate inflammation 5 cm cranial to the catheter tip. A dose of 3 mg/day produced no neurotoxicity and spinal histopathologic changes that were equivalent to those observed in the saline-treated animals.