The abolishment of anesthesia-induced cognitive impairment by timely protection of mitochondria in the developing rat brain: the importance of free oxygen radicals and mitochondrial integrity

Early exposure to general anesthesia (GA) causes developmental neuroapoptosis in the mammalian brain and long-term cognitive impairment. Recent evidence suggests that GA also causes functional and morphological impairment of the immature neuronal mitochondria. Injured mitochondria could be a significant source of reactive oxygen species (ROS), which, if not scavenged in timely fashion, may cause excessive lipid peroxidation and damage of cellular membranes. We examined whether early exposure to GA results in ROS upregulation and whether mitochondrial protection and ROS scavenging prevent GA-induced pathomorphological and behavioral impairments. We exposed 7-day-old rats to GA with or without either EUK-134, a synthetic ROS scavenger, or R(+) pramipexole (PPX), a synthetic aminobenzothiazol derivative that restores mitochondrial integrity. We found that GA causes extensive ROS upregulation and lipid peroxidation, as well as mitochondrial injury and neuronal loss in the subiculum. As compared to rats given only GA, those also given PPX or EUK-134 had significantly downregulated lipid peroxidation, preserved mitochondrial integrity, and significantly less neuronal loss. The subiculum is highly intertwined with the hippocampal CA1 region, anterior thalamic nuclei, and both entorhinal and cingulate cortices; hence, it is important in cognitive development. We found that PPX or EUK-134 co-treatment completely prevented GA-induced cognitive impairment. Because mitochondria are vulnerable to GA-induced developmental neurotoxicity, they could be an important therapeutic target for adjuvant therapy aimed at improving the safety of commonly used GAs.

Abstract P6-04-05: Digital Quantification of Post-Neoadjuvant Chemotherapy Breast Tumor RNA Reveals a Basal-Derived Gene Signature Associated with Post-Treatment Ki67

Neoadjuvant chemotherapy (NAC) leads to a pathological complete response (pCR) in -20% of patients with breast cancer. The rest of the patients exhibit residual disease (RD) in the breast after NAC and are more likely to have a metastatic recurrence. Recent data show that tumor cell proliferation, as measured by Ki67 in the residual post-NAC cancer, can inform clinical outcome. We hypothesized that RD after NAC will harbor different gene expression as a function of Ki67 index. A 2nd hypothesis is that identification of key alterations in tumors with post-NAC high Ki67 will identify molecules or networks that can be therapeutically targeted in the immediate post-operative setting to eradicate clinically silent micro-metastases.

We utilized Nanostring digital RNA quantification to measure the expression of 350 genes in 49 post-NAC residual breast cancers. The cohort was enriched for triple-negative cancers (24/49). Genes were selected based on relevance to breast cancer, published prognostic signatures, and our own unsupervised class discovery approach from existing microarray data. For the selected gene sets, we included a chemo-resistance signature (CHEMO), a stroma signature (STROMA), and a WNT/metastasis signature (WNT/MET). For the unsupervised analysis, publicly available pre-treatment microarray data from chemotherapy-treated ER-breastcancers that did not achieve pCR were clustered and the two most prominent groups were used to select a 250 gene set (CLUSTER). Ki67 was assessed in the RD for the 49 tumors and correlated to absolute RNA counts of the 350 selected genes.

Ki67 was strongly associated with subtype as defined by the PAM50 classifier (P<0.0001). Basal tumors demonstrated the highest Ki67, followed by Luminal B, HER2, and Luminal A tumors (median = 63.5, 27, 22.6, and 5.5%, respectively). The CHEMO signature correlated inversely with Ki67 index (p=2.5e-8): paradoxically, genes positively associated with a higher probability of pCR correlated with a high Ki67 in the post-NAC specimens. Thus, chemotherapy-enriched tumors demonstrate distinct and unexpected gene expression patterns after treatment. The WNT/MET and STROMA gene sets showed significant trends with similar directionality to the CHEMO gene set. Our CLUSTER gene set was highly predictive of Ki67 (p=3.6e-6) and robustly associated with basal subtype (p=2.6e-13). MELK, an anti-apoptotic kinase involved in activation of Bcl-G was positively associated with a high Ki67 independently of tumor subtype (p=0.035 and p=0.045 in luminal and basal, respectively). In luminal tumors, high expression of BRCA1, BRCA2, and RRM2 was associated with high Ki67 (p=0.027, 0.016, and 7e-5, respectively), while reduced DUSP4 expression, a MAPK phosphatase, was predictive of high Ki67 in basal post-NAC tumors (p=6e-4).

Existing gene expression predictors built on pre-treatment data did not match expected patterns in chemotherapy-enriched tumors. Breast cancer subtype was strongly associated with a chemotherapy-refractory high Ki67 index in the surgically removed tumors. Further, the assessment of gene expression patterns in RD may be important in ascertaining the molecular underpinnings of aggressive disease. Thus, our defined gene signature may offer insights into molecular targets in patients who do not achieve pCR after NAC.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-04-05.

Inhibition of mammalian target of rapamycin is required for optimal antitumor effect of HER2 inhibitors against HER2-overexpressing cancer cells

PURPOSE

A significant fraction of HER2-overexpressing breast cancers exhibit resistance to the HER2 antibody trastuzumab. Hyperactivity of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway confers trastuzumab resistance, and mammalian target of rapamycin (mTOR) is a major downstream effector of PI3K/AKT. Therefore, we examined whether mTOR inhibitors synergize with trastuzumab.

EXPERIMENTAL DESIGN

Immunocompetent mice bearing HER2(+) mammary tumors were treated with trastuzumab, the mTOR inhibitor rapamycin, or the combination. Mice were imaged for tumor cell death using an optical Annexin-V probe and with [(18)F]FDG positron emission tomography. The signaling and growth effects of the mTOR inhibitor RAD001 on HER2(+) cells treated with trastuzumab or lapatinib were evaluated.

RESULTS

Treatment of mice with trastuzumab plus rapamycin was more effective than single-agent treatments, inducing complete regression of 26 of 26 tumors. The combination induced tumor cell death (Annexin-V binding) and inhibited FDG uptake. Rapamycin inhibited mTOR and tumor cell proliferation as determined by phosphorylated S6 and Ki-67 immunohistochemistry, respectively. In culture, the combination of RAD001 plus trastuzumab inhibited cell growth more effectively than either drug alone. Trastuzumab partially decreased PI3K but not mTOR activity. Knockdown of TSC2 resulted in HER2-independent activation of mTOR and dampened the response to trastuzumab and lapatinib. Treatment with the HER2 inhibitor lapatinib decreased phosphorylated S6 and growth in TSC2-expressing cells but not in TSC2-knockdown cells.

CONCLUSIONS

Inhibition of PI3K and mTOR are required for the growth-inhibitory effect of HER2 antagonists. These findings collectively support the combined use of trastuzumab and mTOR inhibitors for the treatment of HER2(+) breast cancer.

Imaging biomarkers predict response to anti-HER2 (ErbB2) therapy in preclinical models of breast cancer

PURPOSE

To evaluate noninvasive imaging methods as predictive biomarkers of response to trastuzumab in mouse models of HER2-overexpressing breast cancer. The correlation between tumor regression and molecular imaging of apoptosis, glucose metabolism, and cellular proliferation was evaluated longitudinally in responding and nonresponding tumor-bearing cohorts.

EXPERIMENTAL DESIGN

Mammary tumors from MMTV/HER2 transgenic female mice were transplanted into syngeneic female mice. BT474 human breast carcinoma cell line xenografts were grown in athymic nude mice. Tumor cell apoptosis (NIR700-Annexin V accumulation), glucose metabolism [2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography ([18F]FDG-PET)], and proliferation [3'-[18F]fluoro-3'-deoxythymidine-PET ([18F]FLT-PET)] were evaluated throughout a biweekly trastuzumab regimen. Imaging metrics were validated by direct measurement of tumor size and immunohistochemical analysis of cleaved caspase-3, phosphorylated AKT, and Ki67.

RESULTS

NIR700-Annexin V accumulated significantly in trastuzumab-treated MMTV/HER2 and BT474 tumors that ultimately regressed but not in nonresponding or vehicle-treated tumors. Uptake of [18F]FDG was not affected by trastuzumab treatment in MMTV/HER2 or BT474 tumors. [18F]FLT-PET imaging predicted trastuzumab response in BT474 tumors but not in MMTV/HER2 tumors, which exhibited modest uptake of [18F]FLT. Close agreement was observed between imaging metrics and immunohistochemical analysis.

CONCLUSIONS

Molecular imaging of apoptosis accurately predicts trastuzumab-induced regression of HER2+ tumors and may warrant clinical exploration to predict early response to neoadjuvant trastuzumab. Trastuzumab does not seem to alter glucose metabolism substantially enough to afford [18F]FDG-PET significant predictive value in this setting. Although promising in one preclinical model, further studies are required to determine the overall value of [18F]FLT-PET as a biomarker of response to trastuzumab in HER2+ breast cancer.

Symmetry-based scalable lossless compression of 3D medical image data

We propose a novel symmetry-based technique for scalable lossless compression of 3D medical image data. The proposed method employs the 2D integer wavelet transform to decorrelate the data and an intraband prediction method to reduce the energy of the sub-bands by exploiting the anatomical symmetries typically present in structural medical images. A modified version of the embedded block coder with optimized truncation (EBCOT), tailored according to the characteristics of the data, encodes the residual data generated after prediction to provide resolution and quality scalability. Performance evaluations on a wide range of real 3D medical images show an average improvement of 15% in lossless compression ratios when compared to other state-of-the art lossless compression methods that also provide resolution and quality scalability including 3D-JPEG2000, JPEG2000, and H.264/AVC intra-coding.

Occupational health and safety status of indigenous and Latino farmworkers in Oregon

Exposure to pesticides poses great risk to agricultural workers and their families. Of the approximately 174,000 agricultural workers in Oregon, studies estimate that up to 40% of the workers in Oregon are indigenous and may be particularly vulnerable to the health risks of working in pesticide treated areas. Surveys conducted with Oregon farmworkers suggest that Latino and indigenous farmworkers differ demographically and may have diverse occupational and health needs. All Latino workers reported Spanish as their native language, while indigenous workers spoke several different native languages. Latino workers were employed mostly in orchards (28%) and nurseries (24%), while indigenous workers were mostly pickers (40%). Indigenous farmworkers reported less frequent suitable occupational safety training, and potentially less knowledge of the health consequences of pesticides. Addressing the barriers to obtaining pesticide health and safety information is of primary importance, given the changing demographics of farmworkers in Oregon. This article concludes with a discussion of these findings and the programmatic activities that have been implemented in Oregon to improve farmworkers' understanding of hazards and rights associated with agricultural work.

Short preoperative treatment with erlotinib inhibits tumor cell proliferation in hormone receptor-positive breast cancers

PURPOSE

To administer the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor erlotinib to patients with operable untreated breast cancer during the immediate preoperative period and to measure an antiproliferative and/or a proapoptotic effect in the post-therapy specimen and determine a biomarker profile associated with evidence of erlotinib-mediated cellular activity.

PATIENTS AND METHODS

Newly diagnosed patients with stages I to IIIA invasive breast cancer were treated with erlotinib 150 mg/d orally for 6 to 14 days until the day before surgery. Erlotinib plasma levels were measured by tandem mass spectrometry the day of surgery. Drug-induced changes in tumor cell proliferation and apoptosis were assessed by Ki67 immunohistochemistry and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling analysis, respectively, in biopsies from the pretherapy and surgical specimens. Biopsies were also evaluated for P-EGFR, P-HER-2, P-MAPK, P-Akt, P-S6, and S118 P-ER alpha.

RESULTS

In drug-sensitive PC9 xenografts, 5 days of treatment with erlotinib were enough to induce a maximal inhibition of cell proliferation and induction of apoptosis. Forty-one patients completed preoperative treatment with erlotinib. Grade <or= 2 rash and diarrhea were the main toxicities. Erlotinib inhibited tumor cell proliferation (Ki67), P-EGFR, and P-HER-2. The inhibition of proliferation occurred in estrogen receptor (ER) -positive but not in human epidermal growth factor receptor 2 (HER-2) -positive or triple-negative cancers. Treatment was associated with a significant reduction of P-MAPK, P-Akt, P-S6, and S118 P-ER alpha in hormone receptor-positive cancers.

CONCLUSION

A presurgical approach to evaluate cellular responses to new drugs is feasible in breast cancer. EGFR inhibitors are worthy of testing against ER-positive breast cancers but are unlikely to have clinical activity against HER-2-positive or triple-negative breast cancers.

Subversion of cell cycle regulatory pathways

Human cytomegalovirus (HCMV) has evolved numerous strategies to commandeer the host cell for producing viral progeny. The virus manipulates host cell cycle pathways from the early stages of infection to stimulate viral DNA replication at the expense of cellular DNA synthesis. At the same time, cell cycle checkpoints are by-passed, preventing apoptosis and allowing sufficient time for the assembly of infectious virus.

Nonlinear analyses of cell proliferation in the central nervous system reveal stochastic and deterministic components

This paper analyzes the dynamics of cell proliferation in the developing central nervous system. Three different algorithms, Fano factor, Allan factor and detrended fluctuations analysis, are used to estimate de scaling exponent of space numerical series obtained by recording the number and position of proliferating cells along the cephalic-caudal axis of the system. It can be concluded that the dynamics of proliferation involves two component: (a) a random noncorrelated stochastic component representing a basal proliferating activity uniformly distributed along the cephalic-caudal axis and (b) a deterministic nonstationary component that imposes a defined global trend to the process. The deterministic nonstationary trend can be interpreted as the effect of a controlling influence operating along the cephalic-caudal axis. This result indicates that the proliferative activity is spatially organized along the cephalic-caudal axis of the system.

Usefulness of clinical, electrocardiographic, and echocardiographic parameters to detect cardiac asynchrony in patients with left ventricular dysfunction secondary to ischemic or nonischemic heart disease

OBJECTIVES

Specific evaluation using echocardiographic Doppler is superior to the measurement of the QRS complex to detect cardiac asynchrony. Nevertheless, no clinical, electrocardiographic, or echocardiographic parameters have been evaluated to obtain an accurate and easy-to-use marker of cardiac asynchrony in patients with depressed left ventricular (LV) ejection fraction. Our aim was to determine whether there is any marker of cardiac asynchrony in patients with LV systolic dysfunction that allows us to obviate the performance of a specific echocardiographic study before cardiac resynchronization therapy.

METHODS

In all, 316 consecutive patients with LV ejection fraction less than 40% were enrolled. Interventricular asynchrony was defined as an interventricular mechanical delay longer than 40 milliseconds. Intraventricular asynchrony was defined as the difference between time from Q wave to LV ejection end and the time from Q wave to the end of the systolic wave of the most delayed basal segment by Doppler tissue imaging greater than 50 milliseconds.

RESULTS

In all, 177 (56%) had ischemic and 139 (44%) had nonischemic heart disease. The logistic regression analysis showed that only the presence of left bundle branch block was an independent predictor of interventricular asynchrony despite the cause of the underlying disease (odds ratio and 95% confidence interval 7.2 [3.9-13.4], P < .001; 5.99 [2.7-13.2], P < .001; and 8.75 [3.2-23.8], P < .001 for the total population, ischemic and nonischemic groups, respectively). Nevertheless, none of the studied parameters was found as a predictor of intraventricular asynchrony.

CONCLUSIONS

The presence of left bundle branch block is a marker of interventricular asynchrony in patients with ventricular dysfunction despite the cause of the underlying cardiac disease. Nevertheless, intraventricular cardiac asynchrony cannot be detected using conventional parameters. A specific echocardiographic evaluation before cardiac resynchronization therapy must be performed in all these patients. Our aim was to determine whether there is any marker of cardiac asynchrony in patients with left ventricular systolic dysfunction that allows us to obviate the performance of a specific echocardiographic study before cardiac resynchronization therapy. Our results showed that only the presence of left bundle branch block was an independent predictor of interventricular asynchrony despite the cause of the underlying disease but none of the studied parameters was found as a predictor of intraventricular asynchrony.

3,4-Methylenedioxymethamphetamine increases pro-interleukin-1beta production and caspase-1 protease activity in frontal cortex, but not in hypothalamus, of Dark Agouti rats: role of interleukin-1beta in neurotoxicity

3,4-Methylenedioxymethamphetamine (ecstasy) increases mature interleukin-1beta production in rat brain shortly after injection. This effect is a consequence of the 3,4-methylenedioxymethamphetamine-induced hyperthermia and is reduced when rats are maintained at low ambient room temperature. Since interleukin-1beta is generated as an inactive 31-kDa precursor protein and processed into mature form by caspase-1, we have now examined the effect of 3,4-methylenedioxymethamphetamine on pro-interleukin-1beta production and caspase-1-like protease activity in the hypothalamus and frontal cortex of Dark Agouti rats. 3,4-Methylenedioxymethamphetamine increased the immunoreactivity of pro-interleukin-1beta in frontal cortex, not in hypothalamus, 3 h and 6 h after administration. Caspase-1-like protease activity was increased in frontal cortex 3 h after 3,4-methylenedioxymethamphetamine injection compared with saline-treated animals. 3,4-Methylenedioxymethamphetamine did not modify the expression of pro-caspase-1 but increased the immunoreactivity for the caspase-1 active cleavage product (p20) in frontal cortex 3 h after dosing. No change on caspase-1-like protease activity was observed in hypothalamus. The basal immunoreactivity of pro-interleukin-1beta and caspase-1-like protease activity was higher in the hypothalamus than in frontal cortex of control (saline-treated) animals. These data indicate that 3,4-methylenedioxymethamphetamine alters, in a region-specific manner, the mechanisms which regulate interleukin-1beta production in the brain of Dark Agouti rats and suggest that the release of interleukin-1beta in hypothalamus may be regulated independently of caspase-1 activation. Administration (i.c.v.) of interleukin-1beta enhanced the 3,4-methylenedioxymethamphetamine-induced long-term loss of brain 5-HT parameters and immediate hyperthermia. Neither of these effects was observed when interleukin-1beta was given into hippocampus. These results indicate that exogenous interleukin-1beta potentiates 3,4-methylenedioxymethamphetamine neurotoxicity as a consequence of its effect on body temperature and suggest that the 3,4-methylenedioxymethamphetamine-induced rise in interleukin-1beta levels could in turn contribute to the maintenance of 3,4-methylenedioxymethamphetamine-induced hyperthermia and subsequent neurotoxicity.

Diagnosis of pit and fissure caries using frequency-domain infrared photothermal radiometry and modulated laser luminescence

Non-intrusive, non-contacting frequency-domain photothermal radiometry (FD-PTR or PTR) and frequency-domain luminescence (FD-LUM or LUM) have been used with 659- and 830-nm laser sources to assess the pits and fissures on the occlusal surfaces of human teeth. Fifty-two human teeth were examined with simultaneous measurements of PTR and LUM and were compared to conventional diagnostic methods including continuous (dc) luminescence (DIAGNOdent), visual inspection and radiographs. To compare each method to the others, sensitivities and specificities were calculated by using histological observations as the gold standard. With the combined criteria of four PTR and LUM signals (two amplitudes and two phases), it was found that the sensitivity of this method was much higher than any of the other methods used in this study, whereas the specificity was comparable to that of dc luminescence diagnostics. Therefore, PTR and LUM, as a combined technique, has the potential to be a reliable tool to diagnose early pit and fissure caries and could provide detailed information about deep lesions. Using the longer wavelength (830-nm) laser source, it has been shown that detection of deeper subsurface lesions than the 659-nm probe provides is possible.

Chronic cyclosporine-induced nephrotoxiciy in heart transplant patients: Long-term benefits of treatment with mycophenolate mofetil and low-dose cyclosporine

BACKGROUND

Cyclosporine-induced nephropathy is a major limitation in heart transplant patients. Cyclosporine dose reduction may lead to substantial early improvement in renal function. Our aim was to study the long-term benefits of therapy with low doses of cyclosporine plus mycophenolate mofetil in heart transplant patients with drug-induced nephrotoxicity.

METHODS

Twenty-five adult heart transplant patients with cyclosporine-related nephrotoxicity (mean posttransplant = 41.7 +/- 25.7 months) were included in the retrospective analysis (22 men, mean age = 58.8 +/- 7.9 years.). Patients were switched from azathioprine to mycophenolate mofetil (1 to 3 g/d), followed by a stepwise reduction in cyclosporine dosage (trough cyclosporine level maintained around 100 ng/mL). Renal function was determined by serial measurements of serum creatinine and glomerular filtration rate at 3-month intervals.

RESULTS

With a mean follow-up of 30 +/- 13 months, the baseline creatinine of 2.37 +/- 0.5 mg/dL decreased to 1.59 +/- 0.40 mg/dL (P < .0001). The baseline glomerular filtration rate of 36.77 +/- 10.10 mL/min improved to 54.98 +/- 13.80 mL/min (P < .0001). The cyclosporine level was the unique independent variable associated with renal functional improvement (partial R(2) = 0.4). Within the first 3 months, renal function displayed a rapid improvement after conversion to mycophenolate mofetil (P < .001), reaching a plateau, without further significant improvement over the course of time.

CONCLUSIONS

Cyclosporine-induced nephrotoxicity is not a progressive, irreversible disease. Reduction in cyclosporine exposure by addition of mycophenolate mofetil is useful to achieve long-term renal functional improvement, thereby avoiding chronic renal failure. A unique, significant factor associated with this improvement was the reduction in cyclosporine level.