Non-thermal irreversible electroporation (N-TIRE) and adjuvant fractionated radiotherapeutic multimodal therapy for intracranial malignant glioma in a canine patient

Non-thermal irreversible electroporation (N-TIRE) has shown promise as an ablative therapy for a variety of soft-tissue neoplasms. Here we describe the therapeutic planning aspects and first clinical application of N-TIRE for the treatment of an inoperable, spontaneous malignant intracranial glioma in a canine patient. The N-TIRE ablation was performed safely, effectively reduced the tumor volume and associated intracranial hypertension, and provided sufficient improvement in neurological function of the patient to safely undergo adjunctive fractionated radiotherapy (RT) according to current standards of care. Complete remission was achieved based on serial magnetic resonance imaging examinations of the brain, although progressive radiation encephalopathy resulted in the death of the dog 149 days after N-TIRE therapy. The length of survival of this patient was comparable to dogs with intracranial tumors treated via standard excisional surgery and adjunctive fractionated external beam RT. Our results illustrate the potential benefits of N-TIRE for in vivo ablation of undesirable brain tissue, especially when traditional methods of cytoreductive surgery are not possible or ideal, and highlight the potential radiosensitizing effects of N-TIRE on the brain.

High-Frequency Irreversible Electroporation for Treatment of Primary Liver Cancer: A Proof-of-Principle Study in Canine Hepatocellular Carcinoma

PURPOSE

To determine the safety and feasibility of percutaneous high-frequency irreversible electroporation (HFIRE) for primary liver cancer and evaluate the HFIRE-induced local immune response.

MATERIALS AND METHODS

HFIRE therapy was delivered percutaneously in 3 canine patients with resectable hepatocellular carcinoma (HCC) in the absence of intraoperative paralytic agents or cardiac synchronization. Pre- and post-HFIRE biopsy samples were processed with histopathology and immunohistochemistry for CD3, CD4, CD8, and CD79a. Blood was collected on days 0, 2, and 4 for complete blood count and chemistry. Numeric models were developed to determine the treatment-specific lethal thresholds for malignant canine liver tissue and healthy porcine liver tissue.

RESULTS

HFIRE resulted in predictable ablation volumes as assessed by posttreatment CT. No detectable cardiac interference and minimal muscle contraction occurred during HFIRE. No clinically significant adverse events occurred secondary to HFIRE. Microscopically, a well-defined ablation zone surrounded by a reactive zone was evident in the majority of samples. This zone was composed primarily of maturing collagen interspersed with CD3+/CD4-/CD8- lymphocytes in a proinflammatory microenvironment. The average ablation volumes for the canine HCC patients and the healthy porcine tissue were 3.89 cm3 ± 0.74 and 1.56 cm3 ± 0.16, respectively (P = .03), and the respective average lethal thresholds were 710 V/cm ± 28.2 and 957 V/cm ± 24.4 V/cm (P = .0004).

CONCLUSIONS

HFIRE can safely and effectively be delivered percutaneously, results in a predictable ablation volume, and is associated with lymphocytic tumor infiltration. This is the first step toward the use of HFIRE for treatment of unresectable liver tumors.

Inducible male infertility by targeted cell ablation in zebrafish testis

To generate a zebrafish model of inducible male sterility, we expressed an Escherichia coli nitroreductase (Ntr) gene in the male germ line of zebrafish. The Ntr gene encodes an enzyme that can convert prodrugs such as metronidazole (Met) to cytotoxins. A fusion protein eGFP:Ntr (fusing Ntr to eGFP) under control of approximately 2 kb putative promoters of the zebrafish testis-specific genes, A-kinase anchoring protein-associated protein (Asp), outer dense fibers (Odf), and sperm acrosomal membrane-associated protein (Sam) was expressed in the male germ line. Three independent and four compound transgenic zebrafish lines expressing eGFP:Ntr were established. Female carriers were fertile, while males exhibited different levels of sterility and appeared normal, otherwise. Developmental analysis shows that germ cells survived and testes were normal before Met treatment, but that the testes of all male transgenic zebrafish exhibited variously depleted prospermatogonia after Met treatment. Particularly in a triple-transgenic line, Tg(AOS-eGFP:Ntr)[Tg(Asp-eGFP:Ntr; Odf-eGFP:Ntr; Sam-eGFP:Ntr)], the transgenic males had very small testes that were virtually devoid of germ cells, and the residual germ cells had almost completely disappeared after 2 weeks of Met treatment. These zebrafish transgenic lines show the complete testis specificity of inducible male sterility after Met treatment and reveal a period of the Ntr/Met ablation activity just prior to formation of the definitive adult spermatogonial cell population. This study demonstrates that combined genetic and pharmacological methods for developing an "infertile breeding technology" have practical application in controlling genetically modified (GM) fish breeding and meet the standards of biological and environment safety for other GM species.

Ovulation synchrony after follicle ablation in mares

Two experiments were performed to determine the efficacy of ultrasound-guided transvaginal follicle ablation for synchronizing ovarian function in mares. The experiments were initiated at random stages of the oestrous cycle in control (nonablated) and follicle-ablated mares. On day 0, all follicles > or =10 mm in diameter were punctured, aspirated and curettaged in ablated mares, and, on day 4, two doses of PGF2alpha were administered with a 12 h interval between the doses to both ablated and nonablated (control) mares. In Expt 1, hCG was administered to the ablated mares on the first or second day after the largest follicle was > or =30 mm in diameter. In Expt 2, hCG was administered to ablated mares 6 days after PGF2alpha administration, at which time the largest follicle was expected to be > or =30 mm in diameter. FSH concentrations increased initially and decreased subsequently in the ablated mares, and the ablation-induced wave (first detection of a follicle > or =10 mm in diameter) was observed 1.9 days after ablation and was synchronous (1-3 days) in 90% of mares. In both Expts 1 and 2, the uniformity of follicular wave emergence among follicle-ablated mares resulted in significantly better synchrony of ovulation after PGF2alpha administration compared with that of control mares. The variation in the interval from PGF2alpha administration to ovulation in ablated mares was reduced further by hCG administration. In the ablation + hCG groups, ovulation synchrony occurred 6-10 days after PGF2alpha administration in Expt 1 (13/16, 81%) and 7-8 days after PGF2alpha administration in Expt 2 (7/8, 88%). The extended period of ovulation in Expt 1 compared with that of Expt 2 (5 versus 2 days) was inherent in the experimental design, as hCG was not administered in Expt 1 until the largest follicle reached > or =30 mm in diameter, whereas in Expt 2 the experimental design was modified such that hCG was administered 6 days after PGF2alpha administration. As a result, in Expt 2 all but one mare in the ablation + hCG group ovulated within a 2 day period; 75% (6/8) ovulated on day 8 after PGF2alpha administration. Combined data from Expts 1 and 2 revealed that 96% (22/23) of the follicle-ablated mares ovulated within 48 h of hCG administration. Significantly more double ovulations were detected in follicle-ablated mares (10/41, 24%) than in control mares (1/21, 5%). The relatively high degree of ovulation synchrony obtained among mares in the present study indicates that this procedure can be used as an alternative method to synchronize ovarian function in horses.

Successful laparotomic ethanol ablation for an adrenal tumour in a dog

Adrenalectomy is the gold standard for canine adrenal tumours, but not always recommended due to patient age, underlying conditions and perioperative mortality. Ethanol ablation is an alternative in human medicine for poor surgical candidates. A 13-year-old neutered female toy-poodle with hypercortisolism presented with severe haematuria. Ultrasonography revealed left adrenal and right kidney tumours. Due to high surgical risk, simultaneous laparotomic right nephroureterectomy and ethanol ablation of the left adrenal tumour were performed. Post-ethanol injection complications included transient hypertension and arrhythmia, which resolved spontaneously. The adrenal tumour size decreased within 2.5 months, and cortisol levels normalised within 8 days, remaining stable for 12 months. No hypercortisolism signs were observed without trilostane until death from renal insufficiency. Autopsy showed that the ablated left adrenal gland was an adrenocortical tumour and had shrunk. Ethanol ablation may be a feasible alternative to adrenalectomy for high-risk canine patients.

Laparoscopic ultrasound-guided microwave ablation of hepatocellular carcinoma in a dog

OBJECTIVE

The aim of the study was to describe laparoscopic ultrasound (LUS) to guide microwave ablation (MWA) of hepatocellular carcinoma (HCC) in a dog.

ANIMALS

A 13-year-old female spayed Husky.

STUDY DESIGN

Case report.

METHODS

The dog was referred for laparoscopic MWA of a caudate lobe HCC measuring 2.7 cm × 1.9 cm× 2.3 cm. Laparoscopic ultrasound was used to guide percutaneous placement of a MWA probe within the caudate lobe mass. LUS was used to determine the tumor margins for placement of the probe within the medial and lateral aspects as well as the center of the mass. Additionally, LUS allowed visualization of vessels within the tumor so they could be avoided during probe placement.

RESULTS

Safe ablation was accomplished, and the dog recovered uneventfully with no complications. Follow-up computed tomography (CT) 3- and 12-months postoperatively revealed complete ablation of the caudate lobe mass. However, progressive increase in size of the right medial lobe mass occurred. Right medial liver lobectomy was performed 13 months after MWA, with a histopathologic diagnosis of HCC. The dog was euthanized 777 days post MWA and 1445 days post initial left lateral lobectomy for HCC.

CONCLUSION

Laparoscopic ultrasound was useful in guiding complete and safe MWA of an HCC in this dog. Laparoscopic ultrasound should be considered when performing laparoscopic MWA of liver lesions in dogs.

Synchronization of follicular wave before superovulation in dromedary camel by means of transvaginal follicle ablation

The synchronization of follicular waves prior to the initiation of superovulation is a prerequisite for successful results. This study investigates the feasibility of applying transvaginal follicle ablation (TFA) as an alternative to hormonal treatments for synchronization in dromedary camels. In experiment 1, the follicular cycle of pre-synchronized and naturally cycling camels (n = 24) was monitored and all structures > 4 mm were ablated in subgroups of animals (n = 4 each) at early, mid, and late stages of the follicular cycle. The appearance and characteristics of the next follicular wave as well as the occurrence and the fate of residual structures were investigated. In experiment 2, sixteen camels were used for superovulation subsequent to follicle ablation or conventional hormonal synchronization in a changeover design and the result of superovulation was compared among the methods. A subset of 88 embryos was transferred to recipients and pregnancy rates and pregnancy loss rates were compared between the synchronization methods. On average, more structures were ablated from naturally cycling camels than pre-synchronized camels. Ablation of larger structures (> 10 mm) resulted in the formation of remnant structures (26.1 %) out of which 52.9 % showed structural and functional luteinization. The next follicular cohort emerged at day 2.16 ± 0.20 and 2.33 ± 0.22 after the ablation, and established dominance at day 9.33 ± 0.35 and 9.16 ± 0.32, in naturally cycling and pre-synchronized animals, respectively, with no significant difference among them (P > 0.05). All camels responded to ovulation induction at day 14 while camels ablated at mid-cycle had smaller follicles (12.88 ± 0.46 mm) at this time point compared to camels ablated at dominance or early cycle (14.13 ± 0.70 and 14.81 ± 0.42 mm, respectively; P < 0.05). A similar number of developed follicles prior to mating (13.81 ± 1.62 vs. 15.12 ± 1.65), corpus luteum (9.75 ± 1.24 vs. 10.43 ± 1.35), transferable (7.56 ± 1.06 vs. 8.50 ± 1.30), and spherical embryos (5.87 ± 1.07 vs. 6.12 ± 089) were obtained in synchronized camels by hormonal and TFA methods, respectively (P > 0.05). Embryos of the TFA group showed a trend for higher embryonic loss rate after transfer compared to the hormonally synchronized group (34.4 % vs. 17.2 %, P < 0.10). In conclusion, follicle ablation was followed by the development of a new follicular wave capable of establishing dominance and ovulation, irrespective of the stage of the follicular cycle in which the procedure is undertaken, and can be used as an alternative way of synchronization in dromedary camels.