A review of the development of histotripsy for extremity tumor ablation with a canine comparative oncology model to inform human treatments

Cancer is a devasting disease resulting in millions of deaths worldwide in both humans and companion animals, including dogs. Treatment of cancer is complex and challenging and therefore often multifaceted, as in the case of osteosarcoma (OS) and soft tissue sarcoma (STS). OS predominantly involves the appendicular skeleton and STS commonly develops in the extremities, resulting in treatment challenges due to the need to balance wide-margin resections to achieve local oncological control against the functional outcomes for the patient. To achieve wide tumor resection, invasive limb salvage surgery is often required, and the patient is at risk for numerous complications which can ultimately lead to impaired limb function and mobility. The advent of tumor ablation techniques offers the exciting potential of developing noninvasive or minimally invasive treatment options for extremity tumors. One promising innovative tumor ablation technique with strong potential to serve as a noninvasive limb salvage treatment for extremity tumor patients is histotripsy. Histotripsy is a novel, noninvasive, non-thermal, and non-ionizing focused ultrasound technique which uses controlled acoustic cavitation to mechanically disintegrate tissue with high precision. In this review, we present the ongoing development of histotripsy as a non-surgical alternative for extremity tumors and highlight the value of spontaneously occurring OS and STS in the pet dog as a comparative oncology research model to advance this field of histotripsy research.

Histotripsy ablation for the treatment of feline injection site sarcomas: a first-in-cat in vivo feasibility study

PURPOSE

Feline soft tissue sarcoma (STS) and injection site sarcoma (fISS) are rapidly growing tumors with low metastatic potential, but locally aggressive behavior. Histotripsy is a non-invasive focused ultrasound therapy using controlled acoustic cavitation to mechanically disintegrate tissue. In this study, we investigated the in vivo safety and feasibility of histotripsy to treat fISS using a custom 1 MHz transducer.

MATERIALS AND METHODS

Three cats with naturally-occurring STS were treated with histotripsy before surgical removal of the tumor 3 to 6 days later. Gross and histological analyses were used to characterize the ablation efficacy of the treatment, and routine immunohistochemistry and batched cytokine analysis were used to investigate the acute immunological effects of histotripsy.

RESULTS

Results showed that histotripsy ablation was achievable and well-tolerated in all three cats. Precise cavitation bubble clouds were generated in all patients, and hematoxylin & eosin stained tissues revealed ablative damage in targeted regions. Immunohistochemical results identified an increase in IBA-1 positive cells in treated tissues, and no significant changes in cytokine concentrations were identified post-treatment.

CONCLUSIONS

Overall, the results of this study demonstrate the safety and feasibility of histotripsy to target and ablate superficial feline STS and fISS tumors and guide the clinical development of histotripsy devices for this application.

Unwitting adult marijuana poisoning: a case series

STUDY PURPOSE

With increasing state legalization, marijuana use has become commonplace throughout much of the United States. Existing literature on unintentional exposure focuses primarily on children.We report on a cluster of adults with unwitting marijuana exposure.

METHODS

A cluster of cases were referred to the Medical Toxicology Service after ingesting marijuana-contaminated food at a family event. We conducted a retrospective analysis of twelve subject charts and a qualitative analysis with six of these subjects who willingly consented to be interviewed about their experiences. The study was approved by the Institutional Review Board.

RESULTS

Three of the subjects (25%) required prolonged observation due to persistent symptoms. Eleven (92%) were urine immunoassay positive for tetrahydrocannabinol (THC). Two subjects (17%) tested positive for ethanol in their blood. Common symptoms experienced by the subjects included confusion (50%), difficulty speaking (67%), nausea (25%), tremors (17%), and feelings of unreality (33%). All interviewed subjects reported sleepiness and three (50%) reported a negative impact on work. Subjects also reported multiple emotions, including anger, confusion, disbelief, and helplessness. None of the cases resulted in admission for critical care or death.

CONCLUSIONS

Our series illuminates effects of unwitting and/or unintentional marijuana exposure in adults. Unintentional marijuana poisonings have increased, but legal and regulatory barriers have limited the study of marijuana outside highly controlled conditions. While the marijuana exposure in this study did not result in admission for critical care or death, it did result in psychological distress and adversely affected work in some cases.

Chlamydia screening for pregnant women aged 16-25 years attending an antenatal service: a cost-effectiveness study

OBJECTIVE

Determine the cost-effectiveness of screening all pregnant women aged 16-25 years for chlamydia compared with selective screening or no screening.

DESIGN

Cost effectiveness based on a decision model.

SETTING

Antenatal clinics in Australia.

SAMPLE

Pregnant women, aged 16-25 years.

METHODS

Using clinical data from a previous study, and outcomes data from the literature, we modelled the short-term perinatal (12-month time horizon) incremental direct costs and outcomes from a government (as the primary third-party funder) perspective for chlamydia screening. Costs were derived from the Medicare Benefits Schedule, Pharmaceutical Benefits Scheme, and average cost-weights reported for hospitalisations classified according to the Australian refined diagnosis-related groups.

MAIN OUTCOME MEASURES

Direct costs of screening and managing chlamydia complications, number of chlamydia cases detected and treated, and the incremental cost-effectiveness ratios were estimated and subjected to sensitivity analyses.

RESULTS

Assuming a chlamydia prevalence rate of 3%, screening all antenatal women aged 16-25 years at their first antenatal visit compared with no screening was $34,931 per quality-adjusted life-years gained. Screening all women could result in cost savings when chlamydia prevalence was higher than 11%. The incremental cost-effectiveness ratios were most sensitive to the assumed prevalence of chlamydia, the probability of pelvic inflammatory disease, the utility weight of a positive chlamydia test and the cost of the chlamydia test and doctor's appointment.

CONCLUSION

From an Australian government perspective, chlamydia screening of all women aged 16-25 years old during one antenatal visit was likely to be cost-effective compared with no screening or selective screening, especially with increasing chlamydia prevalence.

TWEETABLE ABSTRACT

Chlamydia screening for all pregnant women aged 16-25 years during an antenatal visit is cost effective.

Frequent chromosomal DNA unbalance in thyroid oncocytic (Hürthle cell) neoplasms detected by comparative genomic hybridization

Thyroid oncocytic (Hürthle cell) neoplasms represent a distinct subset of follicular thyroid tumors characterized by abnormal accumulation of mitochondria, whose chromosomal abnormalities have never been systematically analyzed. We have used comparative genomic hybridization to investigate chromosomal DNA alterations in 11 thyroid oncocytic tumors (7 adenomas and 4 carcinomas). Unbalanced chromosomal DNA profiles were detected in 6 of 7 adenomas and 3 of 4 carcinomas, numerical chromosomal aberrations being the dominant feature. Comparative genomic hybridization findings are compatible with two separate groups of tumors with karyotypic abnormalities, one characterized by multiple chromosomal gains with polysomy of chromosomes 5 and 7, the other by loss of chromosome 2. Pathologic and clinical features were similar in the two groups with no difference observed between adenomas and carcinomas. Activating H-, K-, or N-Ras mutations are commonly detected in follicular adenomas and carcinomas of the thyroid gland. However, Ras mutational analysis demonstrated that only one of the tumors in this series, an oncocytic carcinoma with a balanced karyotype, had activating Ras mutations (at codon 13 of K-Ras). The lack of Ras mutations in the 9 oncocytic neoplasms exhibiting chromosomal aneuploidy indicates that numerical chromosomal abnormalities are independent of activating Ras mutations in oncocytic tumors.

Investigation of the regiospecificity and stereospecificity of proton transfer in the yeast inorganic pyrophosphatase catalyzed reaction

The regiospecificity and stereospecificity of proton transfer in the yeast inorganic pyrophosphatase (PPase) catalyzed hydrolysis of P1,P2-bidentate Mg(H2O)4(PPi)2- were probed with exchange-inert metal complexes of imidodiphosphate (PNP) and thiopyrophosphate (PPS). PPase was unable to catalyze the hydrolysis of Mg(H2O)4PNP and P1,P2-bidentate Co(NH3)4PNP under conditions that resulted in rapid hydrolysis of the corresponding metal-PPi complexes. PPase was found to catalyze the hydrolysis of Mg(H2O)4PPS at 17% the rate of Mg(H2O)4PPi hydrolysis. The Km of Mg(H2O)4PPS was determined to be 300 microM, which is a value 10-fold greater than that observed for Mg(H2O)4PPi. P1,P2-Bidentate Cr(H2O)4PPS and Co(NH3)4PPS (prepared from PPS) were both found to be substrates for PPase. The enzyme specifically catalyzed the hydrolysis of the Rp enantiomers of these complexes and not the Sp enantiomers. These results are accommodated by a reaction mechanism involving enzyme-mediated proton transfer to the pro-R oxygen atom of the incipient phosphoryl leaving group of the bound P1,P2-bidentate Mg(H2O)4PPi2- complex.