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MDR1/gp170 expression in breast tumors is associated with treatment and with a poor response to chemotherapy. The data are consistent with a contributory role for MDR1/gp170 in the multidrug resistance in some breast tumors.

Resistance to chemotherapy is a critical issue in the management of breast cancer patients. The nature of clinical drug resistance is likely to be multifactorial. However, in the last decade considerable attention has been dedicated to the role played by membrane transporter proteins belonging to the ATP binding cassette protein superfamily, and in particular by the MDR1 product P-glycoprotein (Pgp) and the multidrug resistance protein (MRP1). Heterogeneity of results is a common feature of studies evaluating the expression and prognostic role of these proteins, due to both methodological and biological factors. Nonetheless, Pgp and MRP1 are detected in a significant proportion of untreated breast cancers (on average 40 and 50% respectively, by immunohistochemistry), without a clear and consistent association with cancer stage. Exposure to chemotherapy increases the expression of both proteins. In vitro studies on primary cultures of breast cancer cells obtained at surgery consistently show an association between Pgp (protein) or MDR1 (mRNA) expression and resistance to chemotherapy. However, the correlation with clinical drug resistance is not as well defined. A stronger association of Pgp/MDR1 with response rates has been observed when expression or an increase in expression are detected immediately following chemotherapy. Correlations with prognosis appear more evident in studies using immunohistochemistry, in adjuvant and neoadjuvant settings. Evidence of clinical reversal of drug resistance by verapamil suggests a functional role of Pgp in drug resistance, although the significance of the evidence is generally weakened by poor trial designs. Future studies should take into account the multifactorial nature of drug resistance in breast cancer and use standardized approaches with adequate controls. Expression studies should be complemented by well-designed trials of drug-resistance reversal using target-specific chemosensitizing agents, and relating the results to the levels of expression of the target proteins.

During the conflicts of the Global War on Terror, which are Operation Enduring Freedom (OEF) in Afghanistan and Operation Iraqi Freedom (OIF), there have been over a quarter of a million diagnosed cases of traumatic brain injury (TBI). The vast majority are due to explosive blast. Although explosive blast TBI (bTBI) shares many clinical features with closed head TBI (cTBI) and penetrating TBI (pTBI), it has unique features, such as early cerebral edema and prolonged cerebral vasospasm. Evolving work suggests that diffuse axonal injury (DAI) seen following explosive blast exposure is different than DAI from focal impact injury. These unique features support the notion that bTBI is a separate and distinct form of TBI. This review summarizes the current state of knowledge pertaining to bTBI. Areas of discussion are: the physics of explosive blast generation, blast wave interaction with the bony calvarium and brain tissue, gross tissue pathophysiology, regional brain injury, and cellular and molecular mechanisms of explosive blast neurotrauma.

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Traumatic brain injury (TBI) due to explosive blast exposure is a leading combat casualty. It is also implicated as a key contributor to war related mental health diseases. A clinically important consequence of all types of TBI is a high risk for development of seizures and epilepsy. Seizures have been reported in patients who have suffered blast injuries in the Global War on Terror but the exact prevalence is unknown. The occurrence of seizures supports the contention that explosive blast leads to both cellular and structural brain pathology. Unfortunately, the exact mechanism by which explosions cause brain injury is unclear, which complicates development of meaningful therapies and mitigation strategies. To help improve understanding, detailed neuropathological analysis is needed. For this, histopathological techniques are extremely valuable and indispensable. In the following we will review the pathological results, including those from immunohistochemical and special staining approaches, from recent preclinical explosive blast studies.

We have established and characterized a series of variant cell lines in which to identify the critical factors associated with E2-induced malignant progression, and the acquisition to tamoxifen resistance in human breast cancer. Sublines of the hormone-dependent MCF-7 cell line (MCF7/MIII and MCF7/LCC1) form stable, invasive, estrogen independent tumors in the mammary fat pads of ovariectomized athymic nude mice. These cells retain expression of both estrogen (ER) and progesterone receptors (PGR), but retain sensitivity to each of the major structural classes of antiestrogens. The tamoxifen-resistant MCF7/LCC2 cells retain sensitivity to the inhibitory effects of the steroidal antiestrogen ICI 182780. By comparing the parental hormone-dependent and variant hormone-independent cells, we have demonstrated an altered expression of some estrogen regulated genes (PGR, pS2, cathepsin D) in the hormone-independent variants. Other genes remain normally estrogen regulated (ER, laminin receptor, EGF-receptor). These data strongly implicate the altered regulation of a specific subset or network of estrogen regulated genes in the malignant progression of human breast cancer. Some of the primary response genes in this network may exhibit dose-response and induction kinetics similar to pS2, which is constitutively upregulated in the MCF7/MIII, MCF7/LCC1 and MCF7/LCC2 cells.