Faculty Bibliography

Wnt/beta-catenin signaling controls various cell fates in metazoan development and is misregulated in several cancers and developmental disorders. Binding of a Wnt ligand to its transmembrane coreceptors inhibits phosphorylation and degradation of the transcriptional coactivator beta-catenin, which then translocates to the nucleus to regulate target gene expression. To understand how Wnt signaling prevents beta-catenin degradation, we focused on the Wnt coreceptor low-density lipoprotein receptor-related protein 6 (LRP6), which is required for signal transduction and is sufficient to activate Wnt signaling when overexpressed. LRP6 has been proposed to stabilize beta-catenin by stimulating degradation of Axin, a scaffold protein required for beta-catenin degradation. In certain systems, however, Wnt-mediated Axin turnover is not detected until after beta-catenin has been stabilized. Thus, LRP6 may also signal through a mechanism distinct from Axin degradation. To establish a biochemically tractable system to test this hypothesis, we expressed and purified the LRP6 intracellular domain from bacteria and show that it promotes beta-catenin stabilization and Axin degradation in Xenopus egg extract. Using an Axin mutant that does not degrade in response to LRP6, we demonstrate that LRP6 can stabilize beta-catenin in the absence of Axin turnover. Through experiments in egg extract and reconstitution with purified proteins, we identify a mechanism whereby LRP6 stabilizes beta-catenin independently of Axin degradation by directly inhibiting GSK3's phosphorylation of beta-catenin.

OBJECTIVE: We sought to explore optimism/pessimism, knowledge of HIV, and attitudes toward HIV screening and treatment among Ghanaian pregnant women. METHOD: Pregnant women in Accra, Ghana, completed a self-administered questionnaire including the Life Orientation Test-Revised (LOT-R, an optimism/pessimism measure), an HIV knowledge and screening attitudes questionnaire, the Short Form 12 (SF-12, a measure of health-related quality of life [HRQOL]), and a demographic questionnaire. Data were analyzed using t-tests, ANOVA, correlations, and the chi2 test. RESULTS: There were 101 participants; 28% were nulliparous. Mean age was 29.7 years, and mean week of gestation was 31.8. All women had heard of AIDS, 27.7% had been tested for HIV before this pregnancy, 46.5% had been tested during this pregnancy, and 59.4% of the sample had ever been tested for HIV. Of those not tested during this pregnancy, 64.2% were willing to be tested. Of all respondents, 89% said they would get tested if antiretroviral drugs (ARVs) were readily available and might prevent maternal-to-child transmission. Neither optimism/pessimism nor HRQOL was associated with attitudes toward HIV screening. Optimism was negatively correlated with HIV knowledge (p = .001) and was positively correlated with having never been tested before this pregnancy (p = .007). CONCLUSION: The relationship between optimism/pessimism and HIV knowledge and screening behavior is worthy of further study using larger samples and objective measures of testing beyond self-report.

Awareness of coronary artery calcium scanning by computed tomography as a reproducible, low-radiation dose means to estimate plaque burden in patients necessitates clinical recommendations for interpretation. Coronary artery calcium scanning is best applied in the intermediate risk, asymptomatic adult population. Calcium scores >100 or >75th percentile transform the intermediate risk patient to high risk with recommendations for more aggressive therapy. Scores exceeding the 90th percentile or >400 define the group at the highest risk of a cardiovascular event and may suggest further cardiac testing. Scores from 11 to 100 and <75th percentile confirm intermediate risk status, and scores from 0 to 10 and <75th percentile convert the patient to low or very low risk.

The mechanism of antimalarial action of the ruthenium-chloroquine complex [RuCl(2)(CQ)](2) (1), previously shown by us to be active in vitro against CQ-resistant strains of Plasmodium falciparum and in vivo against P. berghei, has been investigated. The complex is rapidly hydrolyzed in aqueous solution to [RuCl(OH(2))(3)(CQ)](2)[Cl](2), which is probably the active species. This compound binds to hematin in solution and inhibits aggregation to beta-hematin at pH approximately 5 to a slightly lower extent than chloroquine diphosphate; more importantly, the heme aggregation inhibition activity of complex 1 is significantly higher than that of CQ when measured at the interface of n-octanol-aqueous acetate buffer mixtures under acidic conditions modeling the food vacuole of the parasite. Partition coefficient measurements confirmed that complex 1 is considerably more lipophilic than CQ in n-octanol-water mixtures at pH approximately 5. This suggests that the principal target of complex 1 is the heme aggregation process, which has recently been reported to be fast and spontaneous at or near water-lipid interfaces. The enhanced antimalarial activity of complex 1 is thus probably due to a higher effective concentration of the drug at or near the interface compared with that of CQ, which accumulates strongly in the aqueous regions of the vacuole under those conditions. Furthermore, the activity of complex 1 against CQ-resistant strains of P. falciparum is probably related to its greater lipophilicity, in line with previous reports indicating a lowered ability of the mutated transmembrane transporter PfCRT to promote the efflux of highly lipophilic drugs. The metal complex also interacts with DNA by intercalation, to a comparable extent and in a similar manner to uncomplexed CQ and therefore DNA binding does not appear to be an important part of the mechanism of antimalarial action in this case.

Dopamine D2 and somatostatin receptors (sstrs) were reported to affect non-functioning pituitary adenoma (NFPA) proliferation in vitro. However, the reported results differ according to the experimental conditions used. We established an experimental protocol allowing reproducible evaluation of NFPA cell proliferation in vitro, to test and compare the antiproliferative effects of dopamine and somatostatin analogs (alone or in combination) with the activity of the dopamine-somatostatin chimeric molecule BIM-23A760. The protocol was utilized by four independent laboratories, studying 38 fibroblast-deprived NFPA cell cultures. Cells were characterized for GH, POMC, sstr1-sstr5, total dopamine D2 receptor (D2R) (in all cases), and D2 receptor long and short isoforms (in 15 out of 38 cases) mRNA expression and for alpha-subunit, LH, and FSH release. D2R, sstr3, and sstr2 mRNAs were consistently observed, with the dominant expression of D2R (2.9+/-2.6 copy/copy beta-glucuronidase; mean+/-s.e.m.), when compared with sstr3 and sstr2 (0.6+/-1.0 and 0.3+/-0.6 respectively). BIM-23A760, a molecule with high affinity for D2R and sstr2, significantly inhibited [3H]thymidine incorporation in 23 out of 38 (60%) NFPA cultures (EC50=1.2 pM and Emax=-33.6+/-3.7%). BIM-23A760 effects were similar to those induced by the selective D2R agonist cabergoline that showed a statistically significant inhibition in 18 out of 27 tumors (compared with a significant inhibition obtained in 17 out of 27 tumors using BIM-23A760, in the same subgroup of adenomas analyzed), while octreotide was effective in 13 out of 27 cases. In conclusion, superimposable data generated in four independent laboratories using a standardized protocol demonstrate that, in vitro, chimeric dopamine/sstr agonists are effective in inhibiting cell proliferation in two-thirds of NFPAs.

OBJECTIVE: Older adults with dementia are frequently hospitalized, and a substantial minority present with (or develop) pain during hospitalization. Although general pain management guidelines are available, care can prove challenging in the setting of dementia. The purposes of this study were to review cases of older demented adults with pain admitted to an inpatient geriatric medicine service, and to identify difficulties in their management, which arise as a consequence of patients' dementia. DESIGN: Case series. SETTING: An urban tertiary care hospital located in New York City. PATIENTS: Adults aged 70 years and older with dementia and pain. RESULTS: Patients with dementia and pain may be 1) unable to describe the qualitative characteristics and associated features of their pain; 2) less able than cognitively intact older adults to alert their care providers to the presence of side effects from pain medicines; and 3) unable to discern variations in the level of pain or compare their current pain to their experience of the day or hours before. These deficits can lead to a delayed or incorrect diagnosis, suffering due to side effects, and overtreatment, which can lead to complications like delirium, bowel problems, and prolong length of stay. CONCLUSIONS: The cases presented herein highlight the need to conduct a thorough cognitive assessment of all older hospitalized patients with pain prior to implementing pain medicines. Research is needed to develop effective strategies for managing pain among demented elders in the acute-care setting

Despite a recall by the FDA, contaminated heparin has apparently remained on the shelves and crash carts. The FDA claims that this chemical has been linked to severe allergic reaction and at least 81 deaths in 11 countries since last year. But the real story here is about the verbal thrashing that heparin, a life-saving treatment for blood clots, strokes and heart attacks, has unfairly taken in the news. Yes, 81 deaths is a lot, until you consider the thousands who are saved by heparin treatment every day