Peggy T. Tinkey

Laparoscopically guided bipolar radiofrequency ablation of areas of porcine liver

AbstractBackground: Bipolar radiofrequency ablation (BRFA) is a promising technique with which to treat unresectable primary and metastatic liver tumors. Its effects on normal liver tissue and postoperative liver function, however, are unknown. We performed this study to determine (1) the feasibility of using laparoscopic ultrasound to guide placement of BRFA needle electrodes in the liver and (2) the histopathologic, hepatic biochemical, and systemic hemodynamic responses to BRFA. Methods: Two BRFA lesions were created in the liver of adult domestic pigs to ablate 8–10% of the normal liver volume. Laparoscopic ultrasound was used to guide creation of one peripheral liver lesion and one central liver lesion (with a major hepatic or portal venous vein branch in the center of the BRFA lesions) in each animal. BRFA of liver tissue was performed by passing 12 W of RF power for 16 min across two 16-gauge active-needle electrodes placed 3 cm apart. Results: All animals survived the procedure without significant hemodynamic alterations during or after BRFA. All animals had a transient elevation in serum transaminase levels that returned to normal within 1 week of the BRFA of liver tissue. Gross and microscopic histopathology of the BRFA lesions revealed 2.0–2.5-cm zones of complete coagulative necrosis around and between the BRFA needle tracks without destruction of major blood vessel walls. Conclusions: This study demonstrates (1) that laparoscopic ultrasound can be used to guide placement of BRFA needles in the liver and (2) that BRFA produces focal destruction of liver without significant systemic hemodynamic responses or alterations in liver function. Further studies of this technique to ablate malignant liver tumors are ongoing.

Novel Antiseptic Urinary Catheters for Prevention of Urinary Tract Infections: Correlation of In Vivo and In Vitro Test Results

ABSTRACT Urinary catheters are widely used for hospitalized patients and are often associated with high rates of urinary tract infection. We evaluated in vitro the antiadherence activity of a novel antiseptic Gendine-coated urinary catheter against several multidrug-resistant bacteria. Gendine-coated urinary catheters were compared to silver hydrogel-coated Foley catheters and uncoated catheters. Bacterial biofilm formation was assessed by quantitative culture and scanning electron microscopy. These data were further correlated to an in vivo rabbit model. We challenged 31 rabbits daily for 4 days by inoculating the urethral meatus with 1.0 × 109 CFU streptomycin-resistant Escherichia coli per day. In vitro, Gendine-coated urinary catheters reduced the CFU of all organisms tested for biofilm adherence compared with uncoated and silver hydrogel-coated catheters (P < 0.004). Scanning electron microscopy analysis showed that a thick biofilm overlaid the control catheter and the silver hydrogel-coated catheters but not the Gendine-coated urinary catheter. Similar results were found with the rabbit model. Bacteriuria was present in 60% of rabbits with uncoated catheters and 71% of those with silver hydrogel-coated catheters (P < 0.01) but not in those with Gendine-coated urinary catheters. No rabbits with Gendine-coated urinary catheters had invasive bladder infections. Histopathologic assessment revealed no differences in toxicity or staining. Gendine-coated urinary catheters were more efficacious in preventing catheter-associated colonization and urinary tract infections than were silver hydrogel-coated Foley catheters and uncoated catheters.

Radiation-induced morphologic changes in the rhesus monkey (Macaca mulatta) brain

The right cerebral hemisphere of 24 rhesus monkeys scheduled for necropsy at the completion of another project were studied histopathologically 1–30 days after a single dose of 60Co‐irradiation. Histopathologically, inflammation and gliosis consistently occurred at specific time points but varied in severity between individuals. Multifocal hemorrhage, edema, and an acute neutrophilic inflammatory response were observed initially whereas perivascular accumulations of lymphocytes were observed in specimens at the end of the study. Microglia/macrophages were most prominent during the first week after irradiation, whereas astrocytes were reactive throughout the observation period. The early clinical manifestations of the central nervous system (CNS), because of brain irradiation in humans, correspond temporally with acute vascular responses, acute and subacute inflammatory cell responses, and subacute demyelination and reactive astrocytic and microglial responses observed in the rhesus monkey. Initial responses of the CNS to gamma‐irradiation may have potential implications for the development of radiation‐induced late injury of the CNS.

Use of the i-STAT portable clinical analyzer in mice

The use of portable chemistry analyzers is an attractive option for obtaining clinical pathology panels in mice, because these analyzers require only small volumes of whole blood. However, in studies with other animals, portable analyzers do not always agree with results obtained using standard laboratory equipment. The authors evaluated the use of the i-STAT handheld portable clinical analyzer compared to the use of standard nonportable laboratory instruments in mice. As shown with other species, the i-STAT results did not always agree with standard laboratory instruments; however, the i-STAT does show reliability for certain chemistry assays.

Glioblastoma multiforme arising in the irradiated spinal cord of a rhesus monkey (Macaca mulatta).

Abstract: An adult female rhesus monkey that had received 44.0 Gy of cobalt 60 radiation to 8 cm of the cervical and upper thoracic spinal cord approximately 2.8 years postirradiation developed a sudden onset of self‐mutilation and loss of function of the right arm followed progressively by loss of function of the left arm and terminally bilateral paresis of the legs. Histopathologic examination of the cervical spinal cord revealed a glioblastoma multiforme that extended from the cervical medullary junction to the sixth cervical vertebrae. Because of the infrequent occurrence of spontaneous neoplasia in rhesus monkeys and the location in the radiation field, the glioblastoma is believed to be radiation induced.

A Pilot Trial of Vascular Targeted Photodynamic Therapy for Renal Tissue

PURPOSE Vascular targeted photodynamic therapy represents the newest generation of photodynamic therapy and a new paradigm for minimally invasive ablative therapy. We report a pilot trial of vascular targeted photodynamic therapy to evaluate the effect on porcine renal tissue. MATERIALS AND METHODS Pigs underwent continuous infusion of WST-09 (Negma-Lerads, Toussous le Noble, France) and concurrent illumination with interstitial laser at a wavelength of 763 nm to the lower pole of the kidney. Drug doses were 0.5 to 1.0 mg/kg and light doses were 100 to 200 J. Nuclear renography was performed on postoperative day 5. On postoperative day 7 arteriography, pyelography, computerized tomography of the abdomen and necropsy were performed. RESULTS Four of 7 animals completed therapy and all evaluations. Three animals died, including 1 of surgical complications and 2 of an anaphylactoid reaction to the Cremophor solvent in the compound. All kidneys in surviving animals functioned on nuclear renography. Renal function remained unchanged. No lesions or urine leakage was visible on imaging. On necropsy lesion size was 5 x 4 x 3 to 7 x 7 x 14 mm depending on the drug/light dose. Histology showed a distinct demarcation between the treated zone and the surrounding parenchyma at higher doses. Lesions were well demarcated with necrotic tubules, glomerular fibrinoid necrosis, capillary loop thrombosis, interstitial hemorrhage and lymphocytic infiltrates. CONCLUSIONS Significant tissue effect with some necrosis was seen at these low drug/light combinations. This study provides the initial proof of principle that justifies further preclinical investigation of vascular targeted photodynamic therapy for renal tumors. A newer, water based formulation should decrease the incidence of reactions in swine. This newer formulation may allow further safe investigation of this novel treatment paradigm.

Stenosing colonic adenocarcinoma in a female rhesus monkey.

Abstract: Laparoscopic surgery was performed on a 16 year‐old female rhesus monkey presenting with chronic lethargy and inappetence. The procedure revealed a “napkin‐ring” stricture located in the ascending large colon. Histologic evaluation of the colonic lesion exhibited large numbers of irregular acini lined by a single layer of well‐differentiated neoplastic epithelial cells. Based on the gross and histopathologic findings a diagnosis of adenocarcinoma of the proximal colon was made.

Validation of a Preclinical Model of Diethylnitrosamine-Induced Hepatic Neoplasia in Yucatan Miniature Pigs

Objective: The purpose of this study was to reduce the time to tumor onset in a diethylnitrosamine (DEN)-induced hepatocellular carcinoma (HCC) swine model via partial liver embolization (PLE) and to characterize the model for use in translational research. Methods: Eight Yucatan miniature pigs were injected intraperitoneally with either saline (n = 2) or DEN (n = 6) solution weekly for 12 weeks. Three of the DEN-treated pigs underwent PLE. The animals underwent periodic radiological evaluation, liver biopsy, and blood sampling, and full necropsy was performed at study termination (∼29 months). Results: All DEN-treated pigs developed hepatic adenoma and HCC. PLE accelerated the time to adenoma development but not to HCC development. Biomarker analysis results showed that IGF1 levels decreased in all DEN-treated pigs as functional liver capacity decreased with progression of HCC. VEGF and IL-6 levels were positively correlated with disease progression. Immunohistochemical probing of HCC tissues demonstrated the expression of several important survival-promoting proteins. Conclusion: To our knowledge, we are the first to demonstrate an accelerated development of hepatic neoplasia in Yucatan miniature pigs. Our HCC swine model closely mimics the human condition (i.e., progressive disease stages and expression of relevant molecular markers) and is a viable translational model.

Transvenous extrahepatic portacaval shunt with use of a modified prototype stent-graft: Experimental study in animals

PURPOSE To evaluate the safety and short-term patency of an experimental transvenous extrahepatic portacaval shunt (TEPS) in an animal model. MATERIALS AND METHODS With use of intravascular ultrasound (IVUS) guidance, the main portal vein (PV) was accessed from the inferior vena cava in six pigs and a TEPS was created with use of a prototype flanged stent-graft. Partial PV embolization was then performed to increase the post-TEPS PV pressure. Baseline and postprocedural hemoglobin and hematocrit measurements were obtained and liver function studies were conducted. Immediate postprocedural computed tomography (CT) of the abdomen was used to identify procedural complications. Follow-up venography was performed at 2, 4, and 12 weeks to assess short-term patency. Necropsy was performed at 3 months. RESULTS IVUS-guided PV access was accomplished with a mean of two punctures per animal (range, 1-4). TEPS creation was successful in five of six animals. One animal was killed immediately after unsuccessful shunt creation after stent-graft misdeployment and hemorrhage. A second animal required the insertion of a conventional stent coaxially because portions of the leading arms were inadvertently deployed in the portacaval space and the initial flow through the shunt was venographically suboptimal. CT images obtained after successful TEPS creation (n = 5) revealed no evidence of hemoperitoneum, and there was no decrease in hemoglobin or hematocrit levels from baseline values. All five TEPSs were widely patent at 2-week and 4-week venography with only mild pseudointimal hyperplasia (<50% diameter stenosis) identified in one shunt. Twelve-week venography and necropsy demonstrated no evidence of shunt stenosis in one animal, less than 50% diameter stenosis in one animal, 50%-75% diameter stenosis in two animals, and shunt occlusion in one animal. CONCLUSION Early results with TEPS with use of a modified prototype flanged stent-graft are promising as a potentially safe alternative means of portal decompression. Additional refinements of the stent-graft delivery process are needed to improve the accuracy of deployment.

Comparison of kidney weight and volume to selected anatomical parameters in the adult female rhesus monkey (Macaca mulatta)

Abstract: In this study, the normal distribution of renal weight and volume was determined and the correlation between the weight and volume and various skeletal measurements taken from radiographs and at necropsy was assessed. Values from 136 female monkeys with complete data (including all bone, radiographic, and kidney measurements) were analyzed. The mean kidney weight was 13 g with a standard deviation (SD) of 2 g. The mean kidney volume was 12 ml, SD 2 ml. The estimation of kidney weight and volume from bone length, age, or body weight was not reliable according to statistical analysis of our data. We did find that all apparently normal adult female rhesus monkeys typically have similar sized kidneys. This information is useful in that it reduces concerns about consistency in experimental subjects.