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Articles by J Park
Total Records ( 4 ) for J Park
  D. G Farwell , J. D Meier , J Park , Y Sun , H Coffman , B Poirier , J Phipps , S Tinling , D. J Enepekides and L. Marcu
 

Objective  To investigate the benefit of using time-resolved, laser-induced fluorescence spectroscopy for diagnosing malignant and premalignant lesions of the oral cavity.

Design  The carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) was applied to 1 cheek pouch of 19 hamsters. The contralateral pouch and the cheek pouches of 3 hamsters without DMBA exposure served as controls.

Setting  University of California, Davis.

Participants  Twenty-two golden/Syrian hamsters.

Intervention  A nitrogen pulse laser was used to induce tissue autofluorescence between the wavelengths of 360 and 650 nm.

Main Outcome Measures  Spectral intensities and time-domain measurements were obtained and compared with the histopathologic findings at each corresponding site.

Results  Spectral intensities and lifetime values at 3 spectral bands (SBs; SB1 = 380 ± 10 nm; SB2 = 460 ± 10 nm, and SB3 = 635 ± 10 nm) allowed for discrimination among healthy epithelium, dysplasia, carcinoma in situ, and invasive carcinoma. The lifetime values at SB2 were the most important when distinguishing the lesions using only time-resolved parameters. An algorithm combining spectral fluorescence parameters derived from both spectral and time-domain parameters (peak intensities, average fluorescence lifetimes, and the Laguerre coefficient [zero-order]) for healthy epithelium, dysplasia, carcinoma in situ, and invasive carcinoma provided the best diagnostic discrimination, with 100%, 100%, 69.2%, and 76.5% sensitivity and 100%, 92.2%, 97.1%, and 96.2% specificity, respectively.

Conclusions  The addition of time-resolved fluorescence-derived parameters significantly improves the capability of fluorescence spectroscopy–based diagnostics in the hamster buccal pouch. This technique provides a potential noninvasive diagnostic instrument for head and neck cancer.

  J Park , Y Kim and J. Chung
  Jeehye Park, Yongsung Kim, and Jongkyeong Chung

Parkinson’s disease (PD), one of the most common neurodegenerative disorders worldwide, currently lacks a cure. Although most PD cases occur sporadically, studies from rare genetic mutations give significant insights into addressing the pathological mechanism of not only familial PD, but also sporadic PD. Recent PD research focuses on generating genetic mutant animal models that recapitulate the features of human PD patients. Significant advances in PD research have resulted from studying Drosophila mutants of several identified PD-associated genes because they show strikingly visible phenotypes. In particular, previous studies with the Drosophila mutants parkin and PINK1, which are two common causative genes among PD familial forms, have suggested strongly that mitochondrial dysfunction is the prominent cause for the PD pathogenesis and that these two PD genes are in a common pathway, with Parkin downstream of PINK1. Recent genetic studies have revealed that the PINK1-Parkin pathway is involved in regulating the mitochondrial remodeling...

  D. M.T Yu , K Ajami , M. G Gall , J Park , C. S Lee , K. A Evans , E. A McLaughlin , M. R Pitman , C. A Abbott , G. W McCaughan and M. D. Gorrell
 

The dipeptidyl peptidase IV (DPIV) enzyme family contains both potential and proven therapeutic targets. Recent reports indicate the presence of DP8 and DP9 in peripheral blood lymphocytes, testis, lung, and brain. For a more comprehensive understanding of DP8 and DP9 tissue and cellular expression, mRNA and enzyme activity were examined. Many organs from C57BL/6 wild-type and DPIV gene-knockout mice were examined; DP8/9 enzyme activity was detected in the immune system, brain, testis, muscle, and epithelia. In situ hybridization localized DP8 and DP9 mRNA to lymphocytes and epithelial cells in liver, gastrointestinal tract, lymph node, spleen, and lung. DP8 and DP9 mRNA was detected in baboon and mouse testis, and DP9 expression was elevated in human testicular cancers. DP8 and DP9 mRNA were ubiquitous in day 17 mouse embryo, with greatest expression in epithelium (skin and gastrointestinal tract) and brain. Thus, DP8 and DP9 are widely expressed enzymes. Their expression in lymphocytes and epithelia indicates potential for roles in the digestive and immune systems. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials. (J Histochem Cytochem 57:1025–1040, 2009)

  J Park and J. S. Choi
 

Plasticity in two input pathways into the lateral nucleus of the amygdala (LA), the medial prefrontal cortex (mPFC) and the sensory thalamus, have been suggested to underlie extinction, suppression of a previously acquired conditioned response (CR) following repeated presentations of the conditioned stimulus (CS). However, little is known about the joint dynamics of the relevant synaptic changes within the LA that accompany fear extinction. Employing a novel training procedure, in which stimulation of the medial geniculate nucleus (MGm) of the thalamus served as the CS, we tested necessary and sufficient conditions for extinction in anesthetized rats. Repeatedly applying the brain-stimulation CS was neither sufficient to produce activation of the mPFC nor behavioral extinction when the animal was under anesthesia. Only when the CS was combined with contingent stimulation of the infralimbic cortex (IL) of the mPFC was the CR markedly reduced, emulating extinction. To elucidate the nature of synaptic alterations linking the extinction procedure with CR suppression, evoked field potentials to IL and MGm stimulations were recorded in the LA. The results showed that paired stimulations of the IL and MGm significantly enhanced the neural response at the IL-LA synapses and reversed conditioning-induced synaptic potentiation at the MGm-LA synapses. Taken together, our results provide strong evidence that dual plasticity within the LA underlies suppression of conditioned fear response following extinction.

 
 
 
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