Motivational Mechanisms and Outcome Expectancies Underlying the Approach Bias toward Addictive Substances

Human behavior can be paradoxical, in that actions can be initiated that are seemingly incongruent with an individual’s explicit desires. This is most commonly observed in drug addiction, where maladaptive behavior (i.e., drug seeking) appears to be compulsive, continuing at great personal cost. Approach biases toward addictive substances have been correlated with actual drug-use in a number of studies, suggesting that this measure can, in some cases, index everyday maladaptive tendencies. At present it is unclear whether this bias to drug cues is a Pavlovian conditioned approach response, a habitual response, the result of a Pavlovian-instrumental transfer process, or a goal-directed action in the sense that expectancy of the rewarding effects of drugs controls approach. We consider this question by combining the theoretical framework of associative learning with the available evidence from approach bias research. Although research investigating the relative contributions of these mechanisms to the approach bias is to date relatively limited, we review existing studies and also outline avenues for future research.

Efficacy of pimobendan in the prevention of congestive heart failure or sudden death in Doberman Pinschers with preclinical dilated cardiomyopathy (the PROTECT Study)

BACKGROUND

The benefit of pimobendan in delaying the progression of preclinical dilated cardiomyopathy (DCM) in Dobermans is not reported.

HYPOTHESIS

That chronic oral administration of pimobendan to Dobermans with preclinical DCM will delay the onset of CHF or sudden death and improve survival.

ANIMALS

Seventy-six client-owned Dobermans recruited at 10 centers in the UK and North America.

METHODS

The trial was a randomized, blinded, placebo-controlled, parallel group multicenter study. Dogs were allocated in a 1:1 ratio to receive pimobendan (Vetmedin capsules) or visually identical placebo. The composite primary endpoint was prospectively defined as either onset of CHF or sudden death. Time to death from all causes was a secondary endpoint.

RESULTS

The proportion of dogs reaching the primary endpoint was not significantly different between groups (P = .1). The median time to the primary endpoint (onset of CHF or sudden death) was significantly longer in the pimobendan (718 days, IQR 441-1152 days) versus the placebo group (441 days, IQR 151-641 days) (log-rank P = 0.0088). The median survival time was significantly longer in the pimobendan (623 days, IQR 491-1531 days) versus the placebo group (466 days, IQR 236-710 days) (log-rank P = .034).

CONCLUSION AND CLINICAL IMPORTANCE

The administration of pimobendan to Dobermans with preclinical DCM prolongs the time to the onset of clinical signs and extends survival. Treatment of dogs in the preclinical phase of this common cardiovascular disorder with pimobendan can lead to improved outcome.

The effect of a polyunsaturated diet upon adipose-tissue fatty acids in young coronary males. A five-year cohort study

The fatty acid composition in the adipose tissue of 38 electrocardiographycally confirmed coronary males, mean age 43.7 years, at ideal weight on a 30%-of-calories controlled-fat diet, containing approximately 11.4% of calories as linoleic acid, was studied. The initial linoleic acid concentration in the adipose tissue was approximately 11 mole % of total fatty acids; for approximately the first 12 months it rose slightly and then rapidly increased to about 20% after 24 months. The overall response is sigmoidal in form and fits the equation: 1/y=0.025+0.066 (0.975)(x) in which y represents the adipose tissue linoleate as mole percentage of total adipose tissue fatty acids and x is the time in months.The relative increase in linoleic acid is not attributable to a decrease in any specific fatty acid.

A dopamine/noradrenaline reuptake inhibitor improves performance in the heat, but only at the maximum therapeutic dose

A maximal dose of bupropion has enabled subjects to maintain a higher power output than reported during the placebo session in the heat. Because this drug is taken in different doses it is important to know if there is a dose-response relationship with regard to exercise at high ambient temperature. Ten well-trained male cyclists ingested placebo (pla; 200 mg) or bupropion (50%, 75%, 100% of maximal dose: bup50: 150 mg; bup75: 225 mg; bup100: 300 mg) the evening before and morning of the experimental trial. Trials were conducted in 30 °C (humidity 48%). Subjects cycled for 60 min at 55% W (max) , immediately followed by a time trial to measure performance. Bup100 improved performance (pla: 33'42" ± 2'06"; bup100: 32'06" ± 1'54"; P = 0.035). Bupropion increased core temperature at the end of exercise, while heart rate was higher only in the bup100 trial (P < 0.05). No changes in rating of perceived exertion (RPE) or thermal sensation were found. Lower doses of bupropion were not ergogenic, indicating there was no dose-response effect. Interestingly, despite an increase in core temperature and improved performance in the maximal dose, there was no change in RPE and thermal sensation, suggesting an altered motivation or drive to continue exercise.

MK-0457, an Aurora kinase and BCR-ABL inhibitor, is active in patients with BCR-ABL T315I leukemia

MK-0457, an Aurora kinase and BCR-ABL inhibitor, was studied on a Phase I/II study in 77 patients with refractory hematologic malignancies. The average number of cycles per patient was 3 (range 1-21). Maximum tolerated doses for a 5-day short infusion and continuous infusion regimens were 40 mg/m(2)/h and 144 mg/m(2)/h, respectively. Drug-related adverse events (AEs) included transient mucositis and alopecia. Eight of 18 patients with BCR-ABL T315I-mutated chronic myelogenous leukemia (44%) had hematologic responses and one of three patients (33%) with Philadelphia chromosome-positive acute lymphoblastic leukemia obtained complete remission. MK-0457 has important activity in patients with leukemias expressing the highly resistant T315I BCR-ABL mutation.

SU-E-I-04: Implementation of a Fast Monte Carlo Scatter Correction for Cone- Beam Computed Tomography

PURPOSE

To improve image quality in cone-beam computed tomography (CBCT) scans by implementation of a fast and accurate MC-based scatter correction algorithm.

METHODS

A Solid WaterTM phantom was imaged on a Varian OBI CBCT scanner using the standard-dose head protocol (100 kVp, 151 mAs, partial-angle). A fast Monte Carlo simulation developed in the EGSnrc framework was used to transport photons through the uncorrected CBCT scan. From the simulation output, the contribution from both primary and scattered photons for each projection image was estimated. Using these estimates, a subtractive scatter correction was performed on the CBCT projection data. This correction procedure was repeated iteratively, using the previous scatter corrected scan as input to the Monte Carlo simulation.

RESULTS

Implementation of the scatter correction algorithm on real CBCT data was shown to help mitigate scatter-induced artifacts, such as cupping and streaking. The scatter corrected images were also shown to have improved accuracy in reconstructed attenuation coefficient values. In a region of interest centered on the Solid Water phantom, the number of voxels agreeing to within 10% of the theoretical attenuation coefficient increased from 46% to 97% after two iterations of the scatter correction.

CONCLUSIONS

These results suggest that the proposed scatter correction algorithm is successful in improving image quality in real CBCT images. The accuracy of the attenuation coefficients extracted from the corrected CBCT scan renders the data suitable for on-the-fly dose recalculations, as well as vastly improved image registration.

The metabolic response to treadmill graded exercise: traditional vs. underwater

The purpose of this study was to determine the metabolic effect(s) of four graded exercise tests (GXT) performed on the underwater treadmill (UWT), and compare them to the results from performing the standard Bruce protocol on a traditional land treadmill (LT). Twelve male Division I college athletes performed the stand Bruce protocol on a LT and 4 different GXT protocols on the UWT. Each test was performed to volitional max. oxygen consumption (VO2), heart rate (HR), respiratory exchange ratio (RER) and blood lactate (BL), which were measured at regular intervals throughout each of the GXTs. A two-way ANOVA with repeated measures was used to determine any main effect among the variables within the protocols and within the stages. Established effects were identified further using Tukey's post-hoc analysis. VO2and HR were positively correlated in all the GXTs, (r=0.992−0.999). When comparing the UWT GXTs to the Bruce, significant (P≤0.001) differences were found within certain stages for each of the dependent variables. While the Bruce resulted in attainment of VO2max, (mean = 55.72±5.92 ml/kg/min), only one of the UWT GXTs resulted in the same level of metabolic stress. At maximum speed and water velocity, the UWT produced a mean VO2of 53.9±3.68 ml/kg/min. HR and RER both increased by stage in all the GXTs as did BL. The onset of blood lactate accumulation (OBLA) was identified in all of the GXTs with the exception of one of the UWTs. Mean BL at OBLA ranged from, 3.12+1.31 to 5.98+4.24 mmol/dl. Our results suggest that an UWT GXT protocol can be developed that would produce metabolic results similar to the Bruce through stage 5. Buoyancy and variation in biomechanics need to be studied further for their effects on energy metabolism while performing work on the UWT. However, this study provides a better understanding of the metabolic demands at different treadmill speeds and water jet settings with the UWT.

A positive feedback loop between HER2 and ADAM12 in human head and neck cancer cells increases migration and invasion

Increased activation of epidermal growth factor receptor (EGFR) family members such as HER2/Erbb2 can result in more aggressive disease, resistance to chemotherapy and reduced survival of head and neck squamous cell carcinoma (HNSCC) patients. In order to identify mechanisms through which these receptor tyrosine kinases accelerate tumor progression, the regulation of metalloprotease expression by EGFR family members was investigated in 11 SCC cell lines. HER2 expression was significantly correlated with ADAM12 (A Disintegrin And Metalloprotease 12) expression in these cell lines and was co-expressed in human head and neck cancers. Inhibition of HER2 or EGFR decreased ADAM12 transcripts while HER2 transfection up-regulated ADAM12 expression. To understand the molecular mechanisms underlying HER2 regulation of ADAM12, we investigated the signaling pathways directing ADAM12 production in SCC cells. Inhibition of phosphatidyl inositol-3-kinase (PI3K) or mammalian Target of Rapamycin (mTOR) decreased ADAM12 transcripts in HER2-expressing SCC cells, while transfection with AKT increased ADAM12 mRNA. Experiments utilizing ADAM12 transfection or siRNA targeting of ADAM12 revealed that the protease increased both the migration and invasiveness of oral SCC cells. Surprisingly, ADAM12 also increased HER2 message, protein levels, and activity through an Ets1-dependent mechanism. Collectively, these results reveal a novel positive activation loop between ADAM12 and HER2 that may contribute to HNSCC progression.

Variability in the measured response of bone to teriparatide

Apparent failures of bone mineral density (BMD) response to teriparatide at spine or hip occur even in a high compliance context (15% spine and 55% hip). Apparent non-responders nevertheless show good biomarker response, suggesting that apparent BMD non-response is due to measurement imprecision. Calcium intake may be an important determinant of hip response.

INTRODUCTION

Individuals vary in response to bone active agents, but that variability is poorly quantified and its basis is not well understood. The study included 203 postmenopausal women with moderately severe osteoporosis, all treated with teriparatide, calcium, and vitamin D. The study was performed at the Creighton University Medical Center, a single site.

METHODS

This is a prospective study of change in bone mineral density and resorption biomarkers over a 12-month treatment period. BMD response at spine and total hip was quantified by computing slopes for each participant's values, and biomarker change by the difference in values across the 12-month study period.

RESULTS

Of the total number of participants, 85.2% exhibited a significant spine BMD response, while only 44.8% had a significant change at the hip. However, mean biomarker response was marginally larger for the BMD non-responders at either site than for the responders, indicating biological, if not measurable densitometric, activity of teriparatide in essentially all participants.

CONCLUSIONS

Occasional apparent failures of BMD response in patients receiving teriparatide are probably not due to failure of response at the level of the bone remodeling apparatus, but instead reflect a combination of measurement imprecision and variable bone remodeling balance. The reason for the latter remains unclear.

Survival Outcomes in Women with Ipsilateral Breast Tumor Relapse: An Analysis of Cohorts Classified Clinically as 'True Recurrence' Versus 'New Primary'

Background:Ipsilateral breast tumor relapse (IBTR) can occur in ∼5-20% of women after breast conserving therapy. Two entities of IBTR have been described: "True Recurrence" (TR), suggested to be cases of regrowth of pre-malignant or malignant cells not completely eradicated by surgery or radiation therapy; and "New Primary" (NP), distinct in histology and located away from the index tumor. Whether these two entities have different prognoses is unclear. This study examined a method of IBTR classification using chart review with pre-defined decision rules to assess histology and tumor location and compared survival between two groups classified as either TR or NP.Methods:Between 1989-1999, 6020 women with newly diagnosed invasive breast cancer, pT1-T2, 0-3 positive nodes, M0, treated with breast conserving surgery with clear margins were referred to the BC Cancer Agency. Of these, 289 cases had pathologically-confirmed IBTR, defined as the first recurrence occurring in the ipsilateral breast. Retrospective chart review was performed to abstract clinical data related to the index tumor and the IBTR. A set of decision rules established a priori (figure 1) was applied to classify these cases as either TR or NP.Time to recurrence, distant-relapse free survival (DRFS), and overall survival (OS) were compared between the two cohorts using Kaplan-Meier and log-rank statistics.Results:Of 289 subjects, 131(45%) were classified as TR, 128 (44%) as NP, and 30 (10%) unclassified due to insufficient information. The distributions of age at diagnosis, age at recurrence, index tumor histology, T size, nodal status, grade, lymphovascular invasion, and estrogen receptor status were similar in the two cohorts, (all p &gt;0.05). The mean time to recurrence was shorter in TR compared to NP patients (4.7 years vs. 6.3 years, p=0.001). Surgical treatment of IBTR differed in the two groups, with 76% mastectomy and 21% local excision only in the TR cohort, compared to 81% mastectomy and 16% local excision only in the NP cohort (p&lt;0.001). Systemic therapy at the time of IBTR also differed in the two groups, with hormone therapy alone used more frequently in the TR compared to the NP cohort (42% vs. 38%, p&lt;0.001); and a smaller proportion of the NP cohort receiving both chemotherapy and hormone therapy compared to the TR cohort (8% vs. 15%, p&lt;0.001). In the TR and NP cohorts, 10-year DRFS were 57% vs. 61%, p=0.59; and 10-year OS were 45% vs. 53%, p=0.67.Conclusions:The median time to recurrence is significantly longer in patients with IBTR classified as 'new primary' compared to 'true recurrence'. Non-statistically significant trends for more favorable DRFS and OS were observed for patients with NP compared to TR tumors. The hypothesis that NP and TR tumors are distinct entities with different survival prognoses requires confirmation with pathology review and molecular analyses.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4116.