Faculty Bibliography

OBJECTIVE:: As approximately 40% of persons with HIV also suffer neurocognitive decline, we sought to assess metabolic dysfunction in the brains of simian immunodeficiency virus (SIV)-infected rhesus macaques, an advanced animal model, in structures involved in cognitive function. We test the hypothesis that SIV-infection produces proton-magnetic resonance spectroscopic imaging (H-MRSI)-observed decline in the neuronal marker, N-acetylaspartate (NAA), and elevations in the glial marker, myo-inositol (mI), and associated creatine (Cr) and choline (Cho) in these structures. DESIGN:: Pre- and 4-6 weeks post-SIV infection (with CD8 T-lymphocyte depletion) was monitored with T2-weighted quantitative MRI and 16 x 16 x 4 multivoxel H-MRSI (TE/TR = 33/1400 ms) in the brains of five rhesus macaques. METHODS:: Exploiting the high-resolution H-MRSI grid, we obtained absolute, cerebrospinal fluid partial volume-corrected NAA, Cr, Cho and mI concentrations from centrum semiovale, caudate nucleus, putamen, thalamus and hippocampus regions. RESULTS:: Pre- to post-infection mean Cr increased in the thalamus: 7.2 +/- 0.4 to 8.0 +/- 0.8 mmol/l (+11%, P < 0.05); mI increased in the centrum semiovale: 5.1 +/- 0.8 to 6.6 +/- 0.8 mmol/l, caudate: 5.7 +/- 0.7 to 7.3 +/- 0.5 mmol/l, thalamus: 6.8 +/- 0.8 to 8.5 +/- 0.8 mmol/l and hippocampus: 7.7 +/- 1.2 to 9.9 +/- 0.4 mmol/l (+29%, +27%, +24% and +29%, all P < 0.05). NAA and Cho changes were not significant. CONCLUSION:: SIV-infection appears to cause brain injury indirectly, through glial activation, while the deep gray matter structures' neuronal cell bodies are relatively spared. Treatment regimens to reduce gliosis may, therefore, prevent neuronal damage and its associated neurocognitive impairment.

Ventricular KATP channels link intracellular energy metabolism to membrane excitability and contractility. We identified plakoglobin (PG) and plakophilin-2 (PKP2) as KATP channel associated proteins and investigated whether the association of KATP channel subunits with junctional proteins translates to heterogeneous subcellular distribution within a cardiac myocyte. Co-immunoprecipitation experiments confirmed physical interaction between KATP channels and PKP2 and PG in rat heart. Immunolocalization experiments demonstrated that KATP channel subunits are expressed at a higher density at the intercalated disk (ICD) in hearts, where they colocalized with PKP2 and PG. Super-resolution microscopy demonstrate that KATP channels are clustered within nanometer distances from junctional proteins. The local KATP channel density was larger at the cell end when compared to local currents recorded from the cell's center. The KATP channel unitary conductance, block by MgATP and activation by MgADP did not differ between these two locations. Whole-cell KATP channel current density was ~40% smaller in myocytes from mice haploinsufficient for PKP2. Experiments with excised patches demonstrated that the regional heterogeneity of KATP channels was absent in the PKP2 deficient mice, but the KATP channel unitary conductance and nucleotide sensitivities remained unaltered. Our data demonstrate heterogeneity of KATP channel distribution within a cardiac myocyte. The higher KATP channel density at the ICD implies a possible role at the intercellular junctions during cardiac ischemia

n-3 fatty acids may decrease cardiovascular disease risk. We questioned if acute intervention of n-3 triglyceride (TG) emulsion (48% of fatty acids = EPA+DHA) is protective and improves cardiac function after ischemia/reperfusion (I/R). n-3 TG were administered after I/R in two models: a) hearts (C57BL/6 mice) were perfused ex-vivo using the Langendorff technique (LT); b) hearts with acute occlusion of the left anterior descending coronary artery (LAD) in vivo. After LAD occlusion n-3 TG emulsion (1.5g/kg body weight) was injected intraperitoneally at the end of ischemia and 1h later. In the LT model of I/R, perfusion with KREBS-Hensleit buffer (KH) led to markedly decreased left ventricular developed pressure (LVDP) (by 60%) and arrhythmias, but reperfusion with KH+ n-3 TG (300mg/100ml) improved LVDP recovery. In the LAD model, near normal echo-and electrocardiograms were maintained 48hrs after I/R and left ventricular infarct size was reduced by 80% in TG treated animals vs control. For both I/R models, markers of injury, lactate dehydrogenase and creatine kinase, were significantly reduced in n-3 TG treated mice. After I/R, in LT model, n-3 TG increased a marker of apoptosis Bcl-2 (by 50%), reduced markers of autophagy beclin 1 (by 60%) and HIF1 (by 80%). We conclude that an acute n-3 TG injection after ischemia provides cardioprotection. This may provide a novel therapy after acute myocardial infarction in humans

Takotsubo cardiomyopathy is an acute reversible cardiac dysfunction syndrome associated with high circulating catecholamine levels. Our objective was to investigate whether abnormal cardiovascular control might play a role in the pathophysiology. We studied autonomic cardiovascular reflexes in 10 women who had takotsubo (33+/-7 months after being hospitalized) and 10 age/BMI matched healthy women. In the women with takotsubo, indices of vagal modulation of heart rate induced by respiration were uniformly reduced (expiratory:inspiratory ratio: p<0.01, pnn50%: p<0.02, rMSSD: p<0.03). Cognitive (stroop test: p<0.03) and emotional arousal (event recall: p<0.05) produced exaggerated pressor responses, without detectable ECG changes. Pressor responses to hemodynamic stimuli were also amplified (Valsalva SBP overshoot: p<0.05). Takotsubo women had increased BP variability in the short-term (St. Dev. SBP: p<0.01). Ambulatory recordings captured an exaggerated morning surge in SBP after awakening from sleep (p<0.05). Cardiovagal baroreflex gain was significantly lower in the takotsubo women (sequence analysis: p<0.01, regression method: p<0.001, transfer function gain: p<0.001). Women with takotsubo have heightened sympathetic responsiveness, labile BP and reduced vagal modulation of the heart. This shift in sympathovagal balance could play a role in the pathophysiology

Cisplatin is the primary chemotherapy for head and neck squamous cell carcinoma (HNSCC). No equally effective chemotherapeutics are available when cisplatin resistance occurs. We hypothesize that DNA methylation of key genes mediates cisplatin resistance; moreover, pretreatment with decitabine, a demethylating agent, restores cisplatin sensitivity by mediating expression of genes that are instrumental to cisplatin resistance. Objectives: 1) Determine whether decitabine treatment of a cisplatin-resistant HNSCC cell line restores the anti-proliferative and apoptotic effects of cisplatin; 2) Evaluate the anti-proliferative effect of decitabine and cisplatin (i.e. combination treatment) on a preclinical HNSCC model; 3) Determine whether combination treatment reduces cancer pain; and 4) Create a "gene expression profile of cisplatin resistance" by analyzing cisplatinsensitive and cisplatin-resistant HNSCC in patients. Methods: SCC-25, a cisplatin-sensitive HNSCC cell line, and SCC-25/CP, a cisplatin-resistant cell line, were pre-treated with 5mM decitabine and then treated with cisplatin (3-300 mM) for 48 hours. Proliferation was quantified with an MTS assay. Apoptosis was quantified with a caspase 3/7 assay. A preclinical model was created by inoculating SCC-25/CP cells into the hind-paw of BALB/ c mice. Twenty-four mice were placed into one of four treatment groups: control sham, decitabine-only, cisplatin- only, or combination treatment. Decitabine (6 mg/kg) was administered on post-inoculation days (PID) seven and nine, and cisplatin (6 mg/kg) was administered on PID 12, 15, 18, and 21. Tumor growth was quantified. Mechanical allodynia (i.e. pain) was quantified with a paw withdrawal assay. Formalin-fixed, paraffin- embedded biopsies were obtained from HNSCC patients who underwent chemotherapy with cisplatin. Tumors were classified as either cisplatin-sensitive (RECIST 3 or 4) or cisplatin-resistant (RECIST 1 or 2). Gene expression was quantified in these two sets of samples. Results: In the in !

Over a decade ago, the fMRI Data Center (fMRIDC) pioneered open-access data sharing in the task-based functional neuroimaging community. Well ahead of its time, the fMRIDC effort encountered logistical, sociocultural and funding barriers that impeded the field-wise instantiation of open-access data sharing. In 2009, ambitions for open-access data sharing were revived in the resting state functional MRI community in the form of two grassroots initiatives: the 1000 Functional Connectomes Project (FCP) and its successor, the International Neuroimaging Datasharing Initiative (INDI). Beyond providing open access to thousands of clinical and non-clinical imaging datasets, the FCP and INDI have demonstrated the feasibility of large-scale data aggregation for hypothesis generation and testing. Yet, the success of the FCP and INDI should not be confused with widespread embracement of open-access data sharing. Reminiscent of the challenges faced by fMRIDC, key controversies persist and include participant privacy, the role of informatics, and the logistical and cultural challenges of establishing an open science ethos. We discuss the FCP and INDI in the context of these challenges, highlighting the promise of current initiatives and suggesting solutions for possible pitfalls.

Microtubule-based axonal transport is believed to become globally disrupted in Alzheimer's disease in part due to alterations of tau expression or phosphorylation. We previously showed that axonal transport rates along retinal ganglion axons are unaffected by deletion of normal mouse tau or by overexpression of wild-type human tau. Here, we report that htau mice expressing 3-fold higher levels of human tau in the absence of mouse tau also display normal fast and slow transport kinetics despite the presence of abnormally hyperphosphorylated tau in some neurons. In addition, markers of slow transport (neurofilament light subunit) and fast transport (snap25) exhibit normal distributions along optic axons of these mice. These studies demonstrate that human tau overexpression, even when associated with a limited degree of tau pathology, does not necessarily impair general axonal transport function in vivo.