Financial errors in dementia: testing a neuroeconomic conceptual framework

Financial errors by patients with dementia can have devastating personal and family consequences. We developed and evaluated a neuroeconomic conceptual framework for understanding financial errors across different dementia syndromes, using a systematic, retrospective, blinded chart review of demographically-balanced cohorts of patients with Alzheimer's disease (AD, n=100) and behavioral variant frontotemporal dementia (bvFTD, n=50). Reviewers recorded specific reports of financial errors according to a conceptual framework identifying patient cognitive and affective characteristics, and contextual influences, conferring susceptibility to each error. Specific financial errors were reported for 49% of AD and 70% of bvFTD patients (p = 0.012). AD patients were more likely than bvFTD patients to make amnestic errors (p < 0.001), while bvFTD patients were more likely to spend excessively (p = 0.004) and to exhibit other behaviors consistent with diminished sensitivity to losses and other negative outcomes (p < 0.001). Exploratory factor analysis identified a social/affective vulnerability factor associated with errors in bvFTD, and a cognitive vulnerability factor associated with errors in AD. Our findings highlight the frequency and functional importance of financial errors as symptoms of AD and bvFTD. A conceptual model derived from neuroeconomic literature identifies factors that influence vulnerability to different types of financial error in different dementia syndromes, with implications for early diagnosis and subsequent risk prevention.

Neuroeconomic measures of social decision-making across the lifespan

Social and decision-making deficits are often the first symptoms of a striking number of neurodegenerative disorders associated with aging. These includes not only disorders that directly impact dopamine and basal ganglia, such as Parkinson’s disorder, but also degeneration in which multiple neural pathways are affected over the course of normal aging. The impact of such deficits can be dramatic, as in cases of financial fraud, which disproportionately affect the elderly. Unlike memory and motor impairments, however, which are readily recognized as symptoms of more serious underlying neurological conditions, social and decision-making deficits often do not elicit comparable concern in the elderly. Furthermore, few behavioral measures exist to quantify these deficits, due in part to our limited knowledge of the core cognitive components or their neurobiological substrates. Here we probe age-related differences in decision-making using a game theory paradigm previously shown to dissociate contributions of basal ganglia and prefrontal regions to behavior. Combined with computational modeling, we provide evidence that age-related changes in elderly participants are driven primarily by an over-reliance in trial-and-error reinforcement learning that does not take into account the strategic context, which may underlie cognitive deficits that contribute to social vulnerability in elderly individuals.

Histology and outcomes of newly detected lung lesions in melanoma patients

BACKGROUND

Melanoma frequently metastasizes to the lung. Improved radiologic techniques may decrease the need for biopsy of such lesions. The aim of this study was to examine factors predictive of a positive biopsy of melanoma.

METHODS

Using the Memorial Sloan-Kettering Cancer Center melanoma database, all patients with melanoma who had undergone biopsy of a suspicious new lung lesion from 1996 to 2009 were identified. Age, date of diagnosis, histology, and stage were obtained. Chart review was carried out to obtain medical history, smoking status, radiological appearance, and histology of lung lesions biopsied.

RESULTS

Two hundred and twenty-nine patients were identified; median age was 63 years; 48% were never smokers; 27% had a prior nonmelanoma cancer; 88% of lung nodules were malignant: 69% melanoma, 19% other cancers. Among 113 patients undergoing positron emission tomography (PET), proportions of benign, melanoma, and nonmelanoma 2-[fluorine-18]fluoro-2-deoxy-D-glucose-avid nodules did not differ (P = 0.53). On multivariable analysis, >stage I melanoma, negative smoking history, multiple lung nodules, and no prior nonmelanoma cancer were significantly associated with a melanoma biopsy result rather than other cancer.

CONCLUSIONS

In this study, 31% of lung lesions were not melanoma. In the subset undergoing PET, this did not differentiate between benign and malignant lesions. Biopsy is mandated in melanoma patients with new lung nodules.

A hierarchical communication model of the antecedents of health care professionals' support for donations after cardiac death

Using structural equation modeling, the direct and indirect impact of five variables on the support of donation after cardiac death from the perspective of health care professionals were investigated: knowledge, trust in the transplant team, whether patients are in a state of irreversibility, whether health care professionals participate in a patient's death, and perceptions about the brain death versus cardiac death donation process. In total, 10/15 relationships posited in the model had significant pathways. The results provide insight into sequential communication strategies for generating support for donations after cardiac death.

Renal granular cell tumour (Abrikossoff tumour): case report and review of the literature

A 52-year-old female was referred to our institute for an incidental renal mass. A homogenously enhancing mass was detected on multidetector CT (MDCT) imaging. Histologically, the tumour was consistent with granular cell tumour (GCT). GCT is a benign tumour that often involves the skin and subcutaneous tissue. Rarely has it been reported to involve the genitourinary system. Here we present the first reported case of GCT with renal involvement along with its MDCT imaging features. The authors also present a review of the literature along with a review of typical MDCT imaging features of enhancing renal masses with emphasis given to renal cell carcinoma and its varying subtypes.

Abstract C6: Phase 1 study of conatumumab (AMG 655), a proapoptotic death receptor-5 agonist antibody, in Japanese patients with advanced solid tumors

Background: Conatumumab is an investigational, fully human monoclonal agonist antibody that binds human death receptor-5 (DR5, TR-2), activates caspases, and induces apoptosis in sensitive tumor cells. The primary objectives of this phase 1 study were to assess the safety, tolerability, and pharmacokinetics (PK) of conatumumab in Japanese patients (pts) with advanced solid tumors.

Method: This is an open-label ascending dose study with a starting dose level of 3 mg/kg. Subsequent doses of 10 mg/kg and 20 mg/kg were planned. Six pts were enrolled into 1 of 3 dose cohorts (3, 10, or 20 mg/kg) of conatumumab administered intravenously once every 2 weeks as a single-agent. No conatumumab was administered on day 43 to allow assessment of terminal PK parameters. Conatumumab receptor occupancy on monocytes was assessed during the first treatment cycle. Pts remained on study until tumor progression or unacceptable toxicities occurred.

Results: Eighteen pts (6 in each dose cohorts) received at least 1 dose of conatumumab; 9 pts were men; median age was 58 years. Tumor types included: colorectal (5), non-small cell lung (4), gastric (2), soft tissue sarcoma (2) and one each of pancreatic cancer, thymoma, mesothelioma, rectal carcinoid and parotid cancer. The grade 3 adverse events included blood creatine phosphokinase increase, pain and increased lipase. One treatment emergent serious adverse event of pain was reported in cohort 2. This serious adverse event was not considered by the investigator to be related to conatumumab. There were no DLTs observed as defined in the protocol. No deaths occurred during treatment or the safety follow-up period. No subjects had an adverse event leading to conatumumab discontinuation. Conatumumab demonstrated dose-linear kinetics with a half-life of 12 to16 days. Pharmacokinetic profiles were similar to those in the Caucasian population. Tumor response data were available for all patients. A best response of stable disease (defined as a lack of progression at the first assessment at 8-weeks) was reported in 9 patients and progressive disease in 9 patients. Monocytes were found to express DR5, and showed a high degree of conatumumab receptor occupancy after treatment at all dose levels.

Conclusions: Conatumumab administered up to 20 mg/kg once every 2 weeks did not result in dose limiting toxicities in Japanese patients with advanced solid tumors. Adverse events and pharmacokinetics were similar to those in the first in human study conducted in the United States.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C6.

The effect of strength training on the force of twitches evoked by corticospinal stimulation in humans

AIM

Although there is considerable evidence that strength training causes adaptations in the central nervous system, many details remain unclear. Here we studied neuromuscular responses to strength training of the wrist by recording electromyographic and twitch responses to transcranial magnetic stimulation (TMS) and cervicomedullary stimulation of the corticospinal tract.

METHODS

Seventeen participants performed 4 weeks (12 sessions) of strength training for the radial deviator (RD) muscles of the wrist (n = 8) or control training without external load (n = 9). TMS recruitment curves were constructed from stimuli at five to eight intensities ranging between 15% below resting motor threshold and maximal stimulator output, both at rest and during isometric wrist extension (EXT) and RD at 10% and 50% of maximal voluntary contraction (MVC). Responses to weak TMS and cervicomedullary stimulation (set to produce a response of 10% maximal M wave amplitude during 10% MVC EXT contraction) were also compared at contraction strengths ranging from 10% to 75% MVC.

RESULTS

Isometric strength increased following strength training (10.7% for the RD MVC, 8.8% for the EXT MVC), but not control training. Strength training also significantly increased the amplitude of TMS- and cervicomedullary-evoked twitches during low-force contractions. Increases in the force-generating capacity of the wrist extensor muscles are unlikely to account for this finding because training did not affect the amplitude of twitches elicited by supra-maximal nerve stimulation.

CONCLUSION

The data suggest that strength training induces adaptations that increase the net gain of corticospinal-motor neuronal projections to the trained muscles.

The Wick in the Candle of Learning

Curiosity has been described as a desire for learning and knowledge, but its underlying mechanisms are not well understood. We scanned subjects with functional magnetic resonance imaging while they read trivia questions. The level of curiosity when reading questions was correlated with activity in caudate regions previously suggested to be involved in anticipated reward. This finding led to a behavioral study, which showed that subjects spent more scarce resources (either limited tokens or waiting time) to find out answers when they were more curious. The functional imaging also showed that curiosity increased activity in memory areas when subjects guessed incorrectly, which suggests that curiosity may enhance memory for surprising new information. This prediction about memory enhancement was confirmed in a behavioral study: Higher curiosity in an initial session was correlated with better recall of surprising answers 1 to 2 weeks later.

The clinical impact and outcomes of immunohistochemistry-only metastases in breast cancer

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Background: Modern surgical and pathologic techniques can detect small volume axillary metastases in breast cancer. The clinical significance of these metastases was evaluated in comparison to patients with negative sentinel lymph nodes (Neg-SN). Methods: Retrospective database review from 1997 through 2003 for eligible patients with unilateral breast cancer and no history of significant non-breast malignancy identified 232 patients with sentinel lymph node (SLN) metastases identified only by immunohistochemical stains (IHC-SN). They were compared to 252 Neg-SN controls selected at random from the same database population. Statistical analysis was performed with 2-sample tests, Kaplan-Meier, and Cox regression methods. Results: IHC-SN patients had worse prognostic features and received more systemic therapy than controls (Table). Age and ER status were similar. In 123 IHC-SN patients treated with axillary dissection (ALND), 16% had macrometastases in the non-SLNs. Only one axillary recurrence occurred in the group of IHC-SN patients without ANLD (n=109). With median follow up of 5 years (range 0.01–12.0), 28 recurrences and 25 deaths occurred. There were no differences between cases and controls for recurrence-free survival (RFS) or overall survival (OS) both by univariate and multivariate models that included variables such as age, tumor size, chemotherapy and hormone therapy [HR 0.99 (95%CI 0.43–2.28, p=0.99) for RFS, HR 2.06 (95%CI 0.79–5.35) p=0.14 for OS]. In IHC-SN patients treated with ALND, patients with positive non-SLNs (n=20) tended to have worse RFS than those with negative non-SLNs (n=103) [RFS 89% vs. 97% at 5 yrs (p=0.06)]. Conclusions: A significant number of IHC-SN patients had a macrometastasis identified at ALND. In patients not undergoing dissection, axillary recurrence was a rare event. However, failure to identify additional metastases by omitting ALND may result in understaging and inadequate systemic treatment in some patients.

[Table: see text]

No significant financial relationships to disclose.

Determinants of outcome in elderly patients with positive sentinel lymph nodes

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Background: Older women are less likely to receive standard of care treatment for breast cancer. This undertreatment may be linked to the perception that elderly patients (pts) may not tolerate or derive benefit from treatment that is often viewed as “too toxic.” Methods: From July 1997 to July 2003, 1,470 pts with invasive cancer with positive sentinel lymph nodes (PSLN) by intraoperative frozen section or final pathologic exam by hematoxylin-eosin and/or immunohistochemistry (IHC). We examined sociodemographic, pathologic, and therapeutic variables that affected the outcome of elderly pts ≥70 years old. A comorbidity score was assigned using Adult Comorbidity Evaluation-27 system. Chi-square, Fisher's exact Wilcoxon tests, and multivariate logistic regression analysis were used. Results: The median age was 53 years (range 21–89) and median tumor size 1.6 cm (range 0.1–11). 1,265 (86.1%) pts were <70 years old and 205 (13.9%) pts were ≥70 years old. 183 (12.5%) pts had IHC only PSLN, 1,021 (69.5%) had 1–3 PSLN, and 266 (18%) ≥4 PSLN. Breast conservation therapy (BCT) was performed in 59.7% of pts. Elderly pts were more likely to have moderate to severe comorbidities (46% vs. 11%, p < 0.0001) and BCT (67% vs. 59%, p = 0.026), compared to pts <70 years old. Elderly pts were less likely to undergo completion ALND (73% vs. 89%, p < 0.0001), adjuvant chemotherapy (43% vs. 90%, p < 0.0001) and radiotherapy following BCT (82% vs. 90%) compared to pts <70 years old. The 5-year disease-free survival (DFS) was not significantly different for elderly pts compared to non-elderly pts (87.7% vs. 91.9%, p = 0.21), on the other hand the 5-year overall survival was significantly worse for elderly pts (80.4% vs. 93.2%, p < 0.0001), a difference that was mainly due to a significantly higher 5-year cumulative incidence of death due to other causes (13.2% vs. 1.9%, p < 0.0001). On multivariate analysis, ER or PR positive status, IHC only PSLN and T1 tumors were the only factors independently associated with improved odds of 5-year DFS. Conclusions: Tumor rather than patient factors were the primary determinants of breast cancer outcomes in our cohort of node positive breast cancer pts. Elderly breast cancer pts with an estimated life expectancy beyond 5 years should receive the same standard of care therapy as their younger counterparts.

No significant financial relationships to disclose.

A phase Ib study to evaluate the safety and efficacy of AMG 655 in combination with gemcitabine (G) in patients (pts) with metastatic pancreatic cancer (PC)

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Background: AMG 655 is an investigational, fully human agonist monoclonal antibody (IgG1) that binds human death receptor 5 (DR5), activates caspases, and induces apoptosis in sensitive tumor cells. In preclinical PC models, cooperative activity is observed when G is added to AMG 655. We performed a multi-center phase I trial to evaluate AMG 655 + G in metastatic PC pts. The primary endpoint was dose-limiting toxicity (DLT). Secondary endpoints included toxicity, pharmacokinetics, antibody formation, objective response rate, progression-free survival (PFS), 6-month and overall survival. Methods: Eligible pts had previously untreated metastatic PC and ECOG PS 0 or 1. Pts enrolled into sequential cohorts and received AMG 655 3 or 10 mg/kg IV days (D) 1 and 15 and G 1000 mg/m2 IV D 1, 8, and 15 every 28 D. CT scans were obtained Q8 weeks. Results: 13 pts (3 mg/kg cohort = 6; 10 mg/kg cohort = 7) enrolled from 7/07–11/07. Pt characteristics: females 61%; ECOG PS 1 69%; median age 65 (range 35–81); liver metastases 77%. Median number of cycles: 6 (range 2–12). There were no DLT. Nine (69%) pts had grade 3–4 toxicity, the most common were: thrombocytopenia (4 pts), neutropenia (2 pts), and abdominal pain (2 pts). No anti-AMG 655 antibodies were detected. After one 3 or 10 mg/kg dose of AMG 655 after G, the Cmax and AUC of AMG 655 were similar to those in the first- in-human single-agent study (LoRusso JCO 2007; 25: abstract 3534). Preliminary data indicate no effect of AMG 655 on PK of G. Partial response 31% (4 pts, 2 unconfirmed); stable disease 38%. Median PFS: 5.3 months (95% CI, 3.5, 6.2); 6-month survival rate: 76.2% (95% CI: 42.7%-91.7%). Conclusions: AMG 655 + G is well-tolerated and may have activity in metastatic pancreatic cancer. A randomized phase II trial of G ± AMG 655 at 10-mg/kg is currently enrolling.

[Table: see text]

Safety and efficacy of AMG 655 plus modified FOLFOX6 (mFOLFOX6) and bevacizumab (B) for the first-line treatment of patients (pts) with metastatic colorectal cancer (mCRC)

4079

Background: AMG 655 is an investigational fully human monoclonal antibody (IgG1) agonist of human death receptor 5 (DR5). AMG 655 activates caspases and induces apoptosis in sensitive tumor cells. The primary objective of this phase 1b study was to determine the maximum tolerated dose (up to a target dose of 10 mg/kg IV every 2 weeks) of AMG 655 that can be safely administered in combination with mFOLFOX6-B to mCRC pts. Methods: Eligible pts were ≥ 18 years old with previously untreated mCRC, ECOG PS of 0 or 1, and adequate hematologic, hepatic, and renal function. Pts were enrolled into sequential cohorts of 3- or 10-mg/kg AMG 655 + mFOLFOX6-B administered on day 1 of each 14-day cycle. Study endpoints included incidence of dose-limiting toxicities (DLT), adverse events (AE), pharmacokinetic (PK) parameters of AMG 655, and objective response rate (by modified RECIST). Results: As of 09/08, 12 pts (6 per cohort) were enrolled and received ≥ 1 cycle of treatment; 8 were female. Median (range) age was 54 (37–75), median (range) time on AMG 655 treatment was 6.9 (1.6 to 11.4+) months; 8 pts continue on study treatment. There were no DLTs in the first 28 days of treatment. Eight pts had grade 3–4 AE; the most common were diarrhea, febrile neutropenia, peripheral neuropathy, neutropenia, DVT, and pulmonary embolism (2 pts each). Post baseline laboratory parameters grade ≥ 3: no ALT and AST; 1 grade 3 bilirubin (due to disease progression), and 3 grade 3 lipase (asymptomatic). No anti-AMG 655 antibodies were detected. AMG 655 PK values (Cmax, Cmin) were similar to those observed with single-agent AMG 655 (LoRusso JCO 2007; 25: abstract 3534). AMG 655 did not appear to affect PK of oxaliplatin or bevacizumab. Best overall tumor response: 5 partial responses (2 unconfirmed, both underwent resection); 6 stable disease; 1 pt had non-measurable disease at baseline. Time to disease progression (3 patients): 8, 42, and 44 weeks. Conclusions: The addition of AMG 655 does not appear to substantially alter the safety profile of mFOLFOX6-B. The randomized phase 2 part of the trial (mFOLFOX6-B ± AMG 655) is in progress.

[Table: see text]

Explicit neural signals reflecting reward uncertainty

The acknowledged importance of uncertainty in economic decision making has stimulated the search for neural signals that could influence learning and inform decision mechanisms. Current views distinguish two forms of uncertainty, namely risk and ambiguity, depending on whether the probability distributions of outcomes are known or unknown. Behavioural neurophysiological studies on dopamine neurons revealed a risk signal, which covaried with the standard deviation or variance of the magnitude of juice rewards and occurred separately from reward value coding. Human imaging studies identified similarly distinct risk signals for monetary rewards in the striatum and orbitofrontal cortex (OFC), thus fulfilling a requirement for the mean variance approach of economic decision theory. The orbitofrontal risk signal covaried with individual risk attitudes, possibly explaining individual differences in risk perception and risky decision making. Ambiguous gambles with incomplete probabilistic information induced stronger brain signals than risky gambles in OFC and amygdala, suggesting that the brain's reward system signals the partial lack of information. The brain can use the uncertainty signals to assess the uncertainty of rewards, influence learning, modulate the value of uncertain rewards and make appropriate behavioural choices between only partly known options.

The right and the good: distributive justice and neural encoding of equity and efficiency

Distributive justice concerns how individuals and societies distribute benefits and burdens in a just or moral manner. We combined distribution choices with functional magnetic resonance imaging to investigate the central problem of distributive justice: the trade-off between equity and efficiency. We found that the putamen responds to efficiency, whereas the insula encodes inequity, and the caudate/septal subgenual region encodes a unified measure of efficiency and inequity (utility). Notably, individual differences in inequity aversion correlate with activity in inequity and utility regions. Against utilitarianism, our results support the deontological intuition that a sense of fairness is fundamental to distributive justice but, as suggested by moral sentimentalists, is rooted in emotional processing. More generally, emotional responses related to norm violations may underlie individual differences in equity considerations and adherence to ethical rules.

Neuroeconomics of decision-making in the aging brain: the example of long-term care

PURPOSE

Long-term care (LTC) services assist people with limitations in the ability to perform activities of daily living (ADLs) as a result of chronic illness or disabilities. We discuss possible behavioral explanations for the under-purchasing of LTC insurance, as well as the current state of knowledge on the neural mechanisms behind these behavioral factors.

FINDINGS/APPROACH

Ideas from behavioral economics are discussed, including risk-seeking over losses, ambiguity-preferring over losses, hyperbolic discounting, and the effect of the aging process on the underlying neural mechanisms supporting these decisions. We further emphasize the role of age, as aging is a highly heterogeneous process. It is associated with changes in both brain tissue as well as cognitive abilities, and both are characterized by large individual differences. Therefore, understanding the neural mechanisms is vital to understanding this heterogeneity and identifying possible methods of interventions.

RESEARCH IMPLICATIONS

LTC financing and insurance is a looming issue in the next 10-20 years. It is important to understand the process by which people make decisions about LTC insurance, heterogeneity in decision processes across individuals, and how these decisions interact with changes in policy and private LTC insurance markets.

ORIGINALITY/VALUE OF THE CHAPTER

By providing an overview of the current state of knowledge in behavioral economics of LTC insurance and the neuroscience of aging, this chapter provides some new directions in the emerging area of neuroeconomics of aging.

Clinical variables are associated with treatment satisfaction in patients with breast, lung, and colorectal cancer

6608

Background: The association between clinical variables (e.g. disease stage/type, side effects, ECOG performance status (PS)) and patient-reported treatment satisfaction has received little attention, despite the potential implications for treatment adherence and decision-making. We examined the relation between clinical variables and treatment satisfaction in a U.S. sample of patients with breast (BC), lung (LC), or colorectal (CRC) cancer using the Cancer Treatment Satisfaction Questionnaire (CTSQ), a recently validated 16-item measure designed to assess expectations of therapy (ET), feelings about side effects (FSE), and satisfaction with therapy (SWT). Methods: Cancer stage, line of therapy, physician-reported ECOG PS, presence vs. absence of medication side effects, and perceived change in cancer over the last two weeks were obtained on patients. These clinical variables were examined in relation to the ET, FSE, and SWT scales of the CTSQ. Higher scale scores indicated better outcomes (e.g., better satisfaction). Group means were compared using one-way ANOVAs; trends of scale scores across clinical variables were also examined. Results: Participants were 349 patients with early and late stage BC (n=137), CRC (n=121), or LC (n=91) who had ≥ 1 cycles of chemo-, bio-, or hormonal therapy in the last 6 months. In all cancer types, FSE differed by presence of side effects (BC<.03; CRC<.01; LC<.02). In BC patients, FSE differed by stage, and ET differed significantly depending on ECOG PS (p<.006) and perceived change (p<.05). For CRC patients, ET significantly differed by stage (p<.05) and perceived change (p<.02); and SWT by presence of side effects (p<.01). SWT also differed by perceived change (p<.01) for LC patients. Most trends were in the expected direction. Conclusions: These results indicate that patient-reported satisfaction with therapy is correlated with clinical variables. On average, patients who perceive less improvement in their cancer, have side effects, and poorer ECOG PS are less satisfied with their current cancer therapy. Unknown is the impact of this relation on adherence and decision-making. Recent changes in healthcare suggests that treatment satisfaction may become an increasingly important measure of clinical outcome.

No significant financial relationships to disclose.

First-in-human study of AMG 655, a pro-apoptotic TRAIL receptor-2 agonist, in adult patients with advanced solid tumors

3534

Introduction: AMG 655 is a fully human monoclonal agonist antibody that binds human TRAIL receptor 2 (TR-2/DR5), activates caspases, and induces apoptosis in sensitive tumor cells. The primary objectives of this ongoing first-in-human study were to assess the safety, tolerability, and pharmacokinetics (PK) of AMG 655 in patients (pts) with advanced solid tumors. Methods: Three to 9 pts were enrolled into 1 of 5 sequential dose cohorts (0.3, 1, 3, 10, or 20 mg/kg) of AMG 655 administered intravenously Q2W. No AMG 655 was administered on day 43 to allow assessment of terminal PK parameters. RECIST and FDG-PET were analyzed by central radiology. Pts remained on study until tumor progression or unacceptable toxicities occurred. Results: As of October 19, 2006, 16 pts (4 in the 10 mg/kg cohort; 3 in each of the other cohorts) had received = 1 dose of AMG 655; 12 pts were men, mean (SD) age was 53 (±8.9) years. No DLTs or AMG 655-related serious AEs were reported. The MTD was not reached. Nine pts reported AMG 655-related AEs. Treatment-related AEs in 3 or more pts were: pyrexia (4 pts), fatigue (3 pts), and hypomagnesaemia (3 pts). Fatigue and elevated serum lipase were the only grade 3 or higher AMG 655-related AEs and both occurred in the same pt (0.3-mg/kg cohort). No anti-AMG 655 antibodies were detected. PK data were available from dose cohorts 1 to 3 (0.3, 1, and 3 mg/kg); AMG 655 demonstrated dose-linear kinetics with a half-life of ∼10 days. Tumor- response data were available for 13 pts. Partial response was observed in 1 pt with non-small cell lung cancer (NSCLC) who experienced a 46% reduction in tumor volume by RECIST and remains on study after 48 weeks. Stable disease was reported in 4 pts (range 6 to 35 weeks), and progressive disease in 8 pts. One pt with colorectal cancer and stable disease demonstrated a metabolic partial response with a 34% reduction in maximum standardized uptake value (SUVmax). Conclusions: AMG 655 administered up to 20 mg/kg Q2W appeared to be well tolerated in these pts. The anti-tumor activity of AMG 655 was confirmed with observation of a partial response in NSCLC and a metabolic partial response in colorectal cancer. Further studies evaluating AMG 655 in combination with chemotherapy and targeted agents are warranted.

No significant financial relationships to disclose.

Correlating 2-MIB and microcystin concentrations with environmental parameters in two reservoirs in South Taiwan

Cyanobacteria are present in many drinking water reservoirs in Taiwan, and some of them may produce off-flavour compounds and natural toxins. To investigate the correlation among two groups of cyanobacterial metabolites, microcystins and 2-methylisoborneol (2-MIB), and other environmental parameters, approximately 22 water quality and meteorological parameters were monitored for two source waters (Moo-Tan and Tseng-Wen reservoirs) in south Taiwan from August 2003 to April 2005. Monitoring results showed that the two groups of cyanobacterial metabolites were present in the source waters. Concentrations of 2-30 ng/L of 2-MIB was observed for the two reservoirs, while that of the total concentrations of the five microcystin congeners measured were between 30 and 340 ng/L. The concentration of both 2-MIB and microcystins showed higher concentrations in warmer seasons. A stepwise regression technique was employed to correlate 2-MIB and microcystins concentrations with all the corresponding water quality and meteorological parameters. Correlations among 2-MIB concentration, microcystin concentration, water temperature and air temperature were found in the water samples collected from both reservoirs. The correlations may provide a simple means for the water utility to anticipate the two groups of cyanobacterial metabolites in the two source waters.

Neural systems responding to degrees of uncertainty in human decision-making

Much is known about how people make decisions under varying levels of probability (risk). Less is known about the neural basis of decision-making when probabilities are uncertain because of missing information (ambiguity). In decision theory, ambiguity about probabilities should not affect choices. Using functional brain imaging, we show that the level of ambiguity in choices correlates positively with activation in the amygdala and orbitofrontal cortex, and negatively with a striatal system. Moreover, striatal activity correlates positively with expected reward. Neurological subjects with orbitofrontal lesions were insensitive to the level of ambiguity and risk in behavioral choices. These data suggest a general neural circuit responding to degrees of uncertainty, contrary to decision theory.

Antigenic variations in the CD4 induced sites of the CCR5-tropic, pathogenic SHIVsf162p3 gp120 variants

In vivo passage of non-pathogenic, CCR5-tropic simian/human immunodeficiency virus (SHIV) - SHIVsf162 resulted in a pathogenic isolate, SHIVsf162p3. In an attempt to characterize envelope (Env)-mediated properties that may contribute to its pathogenicity, major (P3 major) and minor (P3 minor) Env gp120 variants were cloned from the plasma of a SHIVsf162p3-infected animal, and expressed in the context of luciferase reporter viruses. Entry mediated by these envelopes and susceptibility to neutralization by CD4 induced-site (CD4i) antibodies (MAbs) was analyzed in comparison to parental SF162. Sequence analysis revealed that the P3 major and minor variant Envs contained 14 and 17 amino acid changes, respectively, compared with SF162. The rank order of entry mediated by the three envelopes was P3 major > SF162 > P3 minor, whereas the reverse order was observed for susceptibility to neutralization by CD4i MAbs. Since CD4i epitopes overlap the coreceptor (CoR) binding site, these findings suggest that the amino acid changes accumulated upon in vivo passage of SHIVsf162 result in Env gp120 structural rearrangements that modulate the exposure and/or conformation of the CoR binding site. This, in turn, led to increased entry and infectivity of the P3 major variant and may be responsible, in part, for the enhanced pathogenicity of SHIVsf162p3.

Selection and characterization of HIV-1 variants resistant to the (+) and (-) enantiomers of 2'-deoxy-3'-oxa-4'-thiocytidine (dOTC)

Human immunodeficiency virus type 1 (HIV-1) variants were selected for resistance against the (+) and (-) enantiomers of a novel nucleoside analogue, 2'-deoxy-3'-oxa-4'-thiocytidine (dOTC), using the infectious molecular clone HXB2D grown in the MT-4 line of human T cells. The variants selected with (+) dOTC were approximately 6-7-fold less sensitive than wild-type virus to this drug. Cloning and sequencing of the complete reverse transcriptase (RT) coding region of these variants identified the M1841 mutation and further selection with virus containing the M1841 substitution led to the appearance of an M184V mutation. In contrast, selection experiments performed with (-) dOTC yielded variants capable of growing in drug concentrations as high as 100 microM, but phenotypic analysis of these viruses revealed near wild-type 50% inhibitory concentration (IC50) values for this compound. Site-directed mutagenesis experiments in which the M1841 and M184V mutations were introduced into HXB2D confirmed the importance of these mutations when viruses were grown in MT4 cells. However, wild-type IC50 values in regard to both (-) and (+) dOTC were obtained when these recombinant viruses were grown in cord blood mononuclear cells (CBMC). Clinical isolates of HIV-1 resistant to lamivudine and containing the M184V substitution also displayed low-level resistance to both (-) and (+) dOTC when grown in CBMC. Finally, cell-free RT assays were performed in the presence of either (-) dOTC triphosphate, (+) dOTC triphosphate, or the triphosphate of a racemic mixture of (+) and (-) dOTC with wild-type and mutated M184V-containing recombinant RT. The data demonstrate chain termination effects of these compounds with regard to both wild-type and mutated enzyme and that the latter was approximately twofold less sensitive than the former to these drugs.

Pre-treatment with R-lipoic acid alleviates the effects of GSH depletion in PC12 cells: implications for Parkinson's disease therapy

Oxidative stress is believed to play a key role in the degeneration of dopaminergic neurons in the substantia nigra (SN) of Parkinson's disease (PD) patients. An important biochemical feature of PD is a significant early depletion in levels of the thiol antioxidant compound glutathione (GSH) which may lead to the generation of reactive oxygen species (ROS), mitochondrial dysfunction, and ultimately to subsequent neuronal cell death. In earlier work from our laboratory, we demonstrated that depletion of GSH in dopaminergic PC12 cells affects mitochondrial integrity and specifically impairs the activity of mitochondrial complex I. Here we report that pre-treatment of PC12 cells with R-lipoic acid acts to prevent depletion of GSH content and preserves the mitochondrial complex I activity which normally is impaired as a consequence of GSH loss.

HIV-1 nucleocapsid protein and the secondary structure of the binary complex formed between tRNA(Lys.3) and viral RNA template play different roles during initiation of (-) strand DNA reverse transcription

In human immunodeficiency virus type 1 (HIV-1), the tRNA(Lys.3) primer and viral RNA template can form a specific complex that is characterized by extensive inter- and intramolecular interactions. Initiation of reverse transcription from this complex has been shown to be distinguished from subsequent elongation by early pausing events, such as at the +1 and +3 nucleotide positions. One major concern regarding the biological relevance of these results is that most kinetic studies of HIV-1 reverse transcription have been performed using tRNA(Lys.3)-viral (v) RNA complexes that were formed by heat annealing. In contrast, tRNA(Lys.3) in viruses is placed onto the primer binding site by nucleocapsid (NC) sequences of the Gag protein. In this study, we have further characterized the initiation features of reverse transcription in the presence of HIV-1 NC protein. In contrast to results obtained with a heat-annealed tRNA(Lys.3).vRNA complex, we found that polymerization reactions catalyzed by HIV-1 reverse transcriptase did not commonly pause at the +1 nucleotide position when a NC-annealed RNA complex was used, and that this was true regardless whether NC was actually still present during reverse transcription. This activity of NC required both zinc finger motifs, as demonstrated by experiments that employed zinc finger-mutated forms of NC protein (H23C NC and ddNC), supporting the involvement of the zinc fingers in the RNA chaperone activity of NC. However, NC was not able to help reverse transcriptase to escape the +3 pausing event. Mutagenesis of a stem structure within the tRNA(Lys.3). vRNA complex led to disappearance of the +3 pausing event as well as to significantly reduced rates of reverse transcription. Thus, this stem structure is essential for optimal reverse transcription, despite its role in promotion of the +3 pausing event.