Rama Pichika
University of California, San Diego
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Publication
Featured researches published by Rama Pichika.
International Journal of Eating Disorders | 2012
Rama Pichika; Monte S. Buchsbaum; Ursula F. Bailer; Carl K. Hoh; Alex DeCastro; Bradley R. Buchsbaum; Walter H. Kaye
OBJECTIVE Physiological and pharmacological studies indicate that altered brain serotonin (5-HT) activity could contribute to a susceptibility to develop appetitive and behavioral alterations that are characteristic of bulimia nervosa (BN). METHOD Eight individuals recovered from BN (REC BN) and eight healthy control women were scanned with [11C]DASB and positron emission tomography imaging of the 5-HT transporter (5-HTT). Logan graphical analysis was applied, and parametric binding potential (BP(nondisplaceable (ND)) ) images were generated. Voxel-by-voxel t-tests and a region of interest (ROI) analysis were conducted. RESULTS REC BN had significantly lower [11C]DASB BP(ND) in midbrain, superior and inferior cingulate and significantly higher [11C]DASB BP(ND) in anterior cingulate and superior temporal gyrus in the voxel-based analysis. ROI analysis indicated lower [11C]DASB BP(ND) in midbrain (p = .07), containing the dorsal raphe, in REC BN, consistent with our earlier studies. DISCUSSION These preliminary findings of a small-scale study confirm and extend previous data suggesting that ill and recovered BN have altered 5-HTT measures, which potentially contribute to BN symptomatology and/or differential responses to medication.
The Journal of Nuclear Medicine | 2012
Rama Pichika; Ameer Y. Taha; Fei Gao; Kishore Kotta; Yewon Cheon; Lisa Chang; Dale O. Kiesewetter; Stanley I. Rapoport; William C. Eckelman
Arachidonic acid (AA) is found in high concentrations in brain phospholipids and is released as a second messenger during neurotransmission and much more so during neuroinflammation and excitotoxicity. Upregulated brain AA metabolism associated with neuroinflammation has been imaged in rodents using [1-14C]AA and with PET in Alzheimer disease patients using [1-11C]AA. Radiotracer brain AA uptake is independent of cerebral blood flow, making it an ideal tracer despite altered brain functional activity. However, the 20.4-min radioactive half-life of 11C-AA and challenges of routinely synthesizing 11C fatty acids limit their translational utility as PET biomarkers. Methods: As a first step to develop a clinically useful 18F-fluoroarachidonic acid (18F-FAA) with a long radioactive half-life of 109.8 min, we report here a high-yield stereoselective synthetic method of nonradioactive 20-19F-FAA. We tested its in vivo pharmacokinetics by infusing purified nonradioactive 19F-FAA intravenously for 5 min at 2 doses in unanesthetized mice and measured its plasma and brain distribution using gas chromatography–mass spectrometry. Results: Incorporation coefficients of injected 19F-FAA into brain phospholipids (ratio of brain 19F-FAA concentration to plasma input function) were 3- to 29-fold higher for choline glycerophospholipid and phosphatidylinositol than for ethanolamine glycerophospholipid and phosphatidylserine at each of the 2 tested doses. The selectivities and values of incorporation coefficients were comparable to those reported after [1-14C]AA (the natural arachidonate) infusion in mice. Conclusion: These results suggest that it would be worthwhile to translate our stereoselective synthetic method for 19F-FAA to synthesize positron-emitting 18F-FAA for human brain AA metabolism in neuroinflammatory disorders such as Alzheimer disease.
Nuclear Medicine and Biology | 2010
Rama Pichika; Douglas M. Jewett; Philip S. Sherman; John R. Traynor; Stephen M. Husbands; James H. Woods; Michael R. Kilbourn
Three new radiolabeled compounds, [(11)C]SNC80 ((+)-4-[(αR)-α-{(2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl}-3-[(11)C]methoxybenzyl-N,N-diethylbenzamide), N,N-diethyl-4-[3-methoxyphenyl-1-[(11)C]methylpiperidin-4-ylidenemethyl)benzamide and N,N-diethyl-4-[(1-[(11)C]methylpiperidin-4-ylidene)phenylmethyl]benzamide, were prepared as potential in vivo radiotracers for the δ-opioid receptor. Each compound was synthesized by alkylation of the appropriate desmethyl compounds using [(11)C]methyl triflate. In vivo biodistribution studies in mice showed very low initial brain uptake of all three compounds and no regional specific binding for [(11)C]SNC80. A monkey positron emission tomography study of [(11)C]SNC80 confirmed low brain permeability and uniform regional distribution of this class of opioid agonists in a higher species. Opioid receptor ligands of this structural class are thus unlikely to succeed as in vivo radiotracers, likely due to efficient exclusion from the brain by the P-glycoprotein efflux transporter.
The Journal of Nuclear Medicine | 2006
Neil Saigal; Rama Pichika; Balasubramaniam Easwaramoorthy; Daphne Collins; Bradley T. Christian; Bingzhi Shi; Tanjore K. Narayanan; Steven G. Potkin; Jogeshwar Mukherjee
The Journal of Nuclear Medicine | 2005
Sankha Chattopadhyay; Baogang Xue; Daphne Collins; Rama Pichika; Rudy Bagnera; Frances M. Leslie; Bradley T. Christian; Bingzhi Shi; Tanjore K. Narayanan; Steven G. Potkin; Jogeshwar Mukherjee
Nuclear Medicine and Biology | 2011
Rama Pichika; Balu Easwaramoorthy; Bradley T. Christian; Bingzhi Shi; Tanjore K. Narayanan; Daphne Collins; Jogeshwar Mukherjee
Journal of Labelled Compounds and Radiopharmaceuticals | 2010
Vivien Nguyen; Rama Pichika; Paayal H. Bhakta; Ritu Kant; Jogeshwar Mukherjee
Society of Nuclear Medicine Annual Meeting Abstracts | 2010
Kenney Vu; Evgueni Sevrioukov; Cristian Constantinescu; Min-Liang Pan; Rama Pichika; Jogesh Mukherjee
Society of Nuclear Medicine Annual Meeting Abstracts | 2008
Balu Easwaramoorthy; Rama Pichika; Cristian Constantinescu; Neil Saigal; Robert Coleman; Jogesh Mukherjee
Society of Nuclear Medicine Annual Meeting Abstracts | 2007
Vivien Nguyen; Rama Pichika; Balasubramaniam Easwaramoorthy; Tanjore K. Narayanan; Bingzhi Shi; Daphne Collins; Jogeshwar Mukherjee