Jurstine Daruwalla

Hyperbaric oxygen therapy for malignancy: a review.

One unique feature of tumors is the presence of hypoxic regions, which occur predominantly at the tumor center. Hypoxia has a major impact on various aspects of tumor cell function and proliferation. Hypoxic tumor cells are relatively insensitive to conventional therapy owing to cellular adaptations effected by the hypoxic microenvironment. Recent efforts have aimed to alter the hypoxic state and to reverse these adaptations to improve treatment outcome. One way to increase tumor oxygen tensions is by hyperbaric oxygen (HBO) therapy. HBO therapy can influence the tumor microenvironment at several levels. It can alter tumor hypoxia, a potent stimulus that drives angiogenesis. Hyperoxia as a result of HBO also produces reactive oxygen species, which can damage tumors by inducing excessive oxidative stress. This review outlines the importance of oxygen to tumors and the mechanisms by which tumors survive under hypoxic conditions. It also presents data from both experimental and clinical studies for the effect of HBO on malignancy.

In vitro and in vivo evaluation of tumor targeting styrene-maleic acid copolymer-pirarubicin micelles: Survival improvement and inhibition of liver metastases

Pirarubicin is a derivative of doxorubicin with improved intracellular uptake and reduced cardiotoxicity. We have prepared a micellar formulation of pirarubicin using styrene‐maleic acid copolymer (SMA) of mean molecular weight of 1.2 kDa, which exhibits a mean diameter of 248 nm in solution. Being a macromolecule, SMA‐pirarubicin micelles exhibit excellent tumor targeting capacity due to the enhanced permeability and retention (EPR) effect. Here we report the antitumor activity of SMA‐pirarubicin micelles on human colon and breast cancer cell lines in vitro, and a murine liver metastasis model in vivo. Metastatic tumor microvasculature, necrosis, apoptosis, proliferation, and survival were also investigated using immunohistochemistry for Ki‐67, active caspase‐3, and CD34, respectively. Drug cytotoxicity in vitro was assessed using MTT (3‐[4,5‐dimethyl‐2‐thiazolyl]‐2, 5‐diphenyl‐2H‐tetrazolium bromide) assay. In vivo, SMA‐pirarubicin was administered at 100, 150, or 200 mg/kg (pirarubicin equivalent). Tumor microvasculature was also assessed using scanning electron microscopy. Styrene‐maleic acid copolymer (SMA)‐pirarubicin micelles were toxic against human colorectal and breast cancer cells in vitro. IC50 was at or below 1 μM, free pirarubicin equivalent. In vivo, SMA‐pirarubicin at 100 mg/kg reduced tumor volume by 80% and achieved a survival rate of 93% at 40 days after tumor inoculation. Styrene‐maleic acid copolymer (SMA)‐pirarubicin micelles demonstrated potent antitumor activity in this liver metastases model, contributing to prolonged survival. Histological examination of tumor nodules showed significant reduction and proliferation of tumor cells (>90%). The present results suggest that investigation of the effect of multiple dosing at later time points to further improve survival is warranted. (Cancer Sci 2010)

Styrene maleic acid-pirarubicin disrupts tumor microcirculation and enhances the permeability of colorectal liver metastases.

Background: Doxorubicin is a commonly used chemotherapy limited by cardiotoxicity. Pirarubicin, derived from doxorubicin, selectively targets tumors when encapsulated in styrene maleic acid (SMA), forming the macromolecular SMA pirarubicin. Selective targeting is achieved because of the enhanced permeability and retention (EPR) effect. SMA-pirarubicin inhibits the growth of colorectal liver metastases, but tumor destruction is incomplete. The role played by the tumor microcirculation is uncertain. This study investigates the pattern of microcirculatory changes following SMA-pirarubicin treatment. Methods: Liver metastases were induced in CBA mice using a murine-derived colon cancer line. SMA-pirarubicin (100 mg/kg total dose) was administered intravenously in 3 separate doses. Twenty-four hours after chemotherapy, the tumor microvasculature was examined using CD34 immunohistochemistry and scanning electron microscopy. Tumor perfusion and permeability were assessed using confocal in vivo microscopy and the Evans blue method. Results: SMA-pirarubicin reduced the microvascular index by 40%. Vascular occlusion and necrosis were extensive following treatment. Viable cells were arranged around tumor vessels. Tumor permeability was also increased. Conclusion: SMA-pirarubicin damages tumor cells and the tumor microvasculature and enhances tumor vessel permeability. However, tumor necrosis is incomplete, and the growth of residual cells is sustained by a microvascular network. Combined therapy with a vascular targeting agent may affect residual cells, allowing more extensive destruction of tumors.

A model of partial hepatectomy in mice.

A versatile, simple, and reproducible model of hepatectomy is essential for the study of liver regeneration and its effects on various pathological processes. A murine model of liver resection and regeneration suitable for research is described. Male inbred CBA mice 6–8 wk old were used in all experiments. The contribution of the hepatic lobes to the total liver mass was determined by wet weight measurements. Resection of 37% (n = 10) and 70% (n = 10) liver volume was performed using hemostatic clips to ligate the hepatic lobe pedicles. Animals were recovered and subsequently killed 21 days postoperatively Liver mass was determined and compared to control animals (n = 17) to assess the completeness of liver regeneration. There were no operative deaths in animals undergoing either 37% or 70% hepatectomy. The procedures could be performed expediently, and animal recovery was complete. Liver mass (grams) assessed 21 days postoperatively [mean (SE)] in both the 37% resection, 1.76 g (0.07), and 70% resection, 1.56 g (0.05), groups was not significantly different from control animals, 1.64 g (0.07) (p =. 265). Thus, partial hepatectomy can be performed safely and rapidly in mice using haemostatic clip ligation of hepatic lobes, with no impairment to the subsequent process of liver regeneration.

Evaluation of the effect of SMA-pirarubicin micelles on colorectal cancer liver metastases and of hyperbaric oxygen in CBA mice

Tetrahydropyranyladriamycin (THP or pirarubicin) destroys tumors via several mechanisms; one of which involves the production of ROS that requires molecular oxygen for its generation. SMA forms stable self-assembled associated micelles with pirarubicin (SMA–pirarubicin), and confers macromolecular characteristics to pirarubicin. This micellar macromolecular drug is selectively delivered to solid tumors via the EPR effect and its preferential tumor accumulation suppresses the systemic toxicity whilst its prolonged high concentration at the site of tumor enhances its efficacy much higher compared to free pirarubicin. Administration of SMA–pirarubicin micelle under HBO can further enhance the delivery of molecular oxygen that facilitates tumor selective generation of ROS, thus augmenting its antitumor potency. In this study, we evaluated the efficacy of SMA–pirarubicin micelles either as single drug or in combination with HBO in a mouse metastatic colorectal cancer model. At or below the maximum tolerated dose, SMA–pirarubicin remarkably reduced metastatic tumor nodules and it was far more effective than free pirarubicin. The data also suggests a potential benefit of combined therapy of HBO with micellar anthracyclins.

Selective targeting of the tumour vasculature.

Selective targeting of the tumour vasculature in the treatment of solid organ malignancies is an alternative to conventional chemotherapy treatment. As the tumour progressively increases in size, angiogenesis or the formation of new vasculature is essential to maintain the tumour’s continual growth and survival. Therefore disrupting this angiogenic process or targeting the neovasculature can potentially hinder or prevent further tumour expansion. Many anti angiogenic agents have been investigated with many currently in clinical trials and exhibiting varied results. Vascular disrupting agents such as the Combretastatins and OXi 4503 have shown promising preclinical results and are currently being examined in clinical trials.

Treatment with the vascular disruptive agent OXi4503 induces an immediate and widespread epithelial to mesenchymal transition in the surviving tumor

Epithelial to mesenchymal transition (EMT) is considered an important mechanism in tumor resistance to drug treatments; however, in vivo observation of this process has been limited. In this study we demonstrated an immediate and widespread EMT involving all surviving tumor cells following treatment of a mouse model of colorectal liver metastases with the vascular disruptive agent OXi4503. EMT was characterized by significant downregulation of E‐cadherin, relocation and nuclear accumulation of β‐catenin as well as significant upregulation of ZEB1 and vimentin. Concomitantly, significant temporal upregulation in hypoxia and the pro‐angiogenic growth factors hypoxia‐inducible factor 1‐alpha, hepatocyte growth factor, vascular endothelial growth factor and transforming growth factor‐beta were seen within the surviving tumor. The process of EMT was transient and by 5 days after treatment tumor cell reversion to epithelial morphology was evident. This reversal, termed mesenchymal to epithelial transition (MET) is a process implicated in the development of new metastases but has not been observed in vivo histologically. Similar EMT changes were observed in response to other antitumor treatments including chemotherapy, thermal ablation, and antiangiogenic treatments in our mouse colorectal metastasis model and in a murine orthotopic breast cancer model after OXi4503 treatment. These results suggest that EMT may be an early mechanism adopted by tumors in response to injury and hypoxic stress, such that inhibition of EMT in combination with other therapies could play a significant role in future cancer therapy.

Laparoscopic or open appendicectomy for suspected appendicitis in pregnancy and evaluation of foetal outcome in Australia

Recent data suggest that laparoscopic appendicectomy (LA) in pregnancy is associated with higher rates of foetal loss when compared to open appendicectomy (OA). However, the influence of gestational age and maternal age, both recognized risk factors for foetal loss, was not assessed.

Styrene maleic acid copolymer-pirarubicin induces tumor-selective oxidative stress and decreases tumor hypoxia as possible treatment of colorectal cancer liver metastases

BACKGROUND Pirarubicin, a derivative of doxorubicin, induces tumor destruction via the production of reactive oxygen species (ROS) but is associated with cardiotoxicity. As a macromolecule (conjugated to styrene-maleic acid [SMA]), SMA-pirarubicin is selective to tumors resulting in improved survival with decreased systemic toxicity. Tumor destruction is, however incomplete, and resistant cells at the periphery of the tumor contribute to recurrence. Tumor hypoxia is a major factor in tumor resistance. Understanding the effect of oxidative stress induced by SMA-pirarubicin on the tumor microenvironment may be key to overcoming resistance. This study investigated the pattern of ROS production and tumor hypoxia after treatment with SMA-pirarubicin in a murine model of colorectal liver metastases. METHODS Liver metastases were induced in male, CBA mice using a murine-derived colon cancer cell line. SMA-pirarubicin (maximum tolerated dose, 100 mg/kg) or pirarubicin, (maximum tolerated dose, 10 mg/kg) were administered intravenously 14 days after tumor induction. Systemic oxidative stress in serum, liver, and cardiac tissue was quantified using the thiobarbituric acid reactive substances assay. Flow cytometry and fluorescence microscopy were used to assess ROS production for 48 hours after treatment. Tumor hypoxia was quantified using immunohistochemistry for pimonidazole adducts. RESULTS SMA-pirarubicin (100 mg/kg) induced ROS exclusively in tumors with minimal levels in serum and cardiac tissue. ROS levels were induced in a time-dependent and dose-dependent manner optimal between 4 and 24 hours after drug administration. Although tumor hypoxia was decreased overall, residual tumor cells adjacent to patent vessels were hypoxic. CONCLUSION This study provides insight into the tumor microenvironment after chemotherapy. SMA-pirarubicin inhibits the growth of colorectal liver metastases by inducing ROS, which seems to be largely tumor selective. The temporal pattern of ROS production can be used to improve future dosing regimens. Furthermore, the observation that residual tumor cells are hypoxic clarifies the need for a multimodal approach with agents that can alter the hypoxic state to effect complete tumor destruction.

Ectopic intravagal parathyroid adenoma.

Intraneural parathyroid adenomas are rare, with only 9 cases of intravagal adenomas reported. All but one of the reported cases was found after multiple neck explorations. To the best of our knowledge, we report the first case of nonsupernumerary ectopic intravagal parathyroid identified at primary exploration.Background Intraneural parathyroid adenomas are rare, with only 9 cases of intravagal adenomas reported. All but one of the reported cases was found after multiple neck explorations. To the best of our knowledge, we report the first case of nonsupernumerary ectopic intravagal parathyroid identified at primary exploration. Methods and Results A 17-year-old girl with primary hyperparathyroidism and nephrolithiasis was referred with a sestamibi scan reporting a left lower parathyroid adenoma. No eutopic parathyroid tissue was identified during full exploration of the left side of the neck. Exploration of the carotid sheath revealed a fusiform swelling of the vagus nerve at the level of the carotid bifurcation. Longitudinal incision of the vagal perineurium revealed a 7-mm parathyroid adenoma, which was enucleated. The patient recovered uneventfully, with normalization of serum calcium, parathyroid hormone (PTH), and normal vocal cord function. Conclusion We believe that this is the first reported case of nonsupernumerary intravagal parathyroid adenoma resected at initial exploration. The vagus nerve is a rare location for a parathyroid adenoma, but one that should be considered, even during primary exploration.