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ABSTRACT: This study evaluates the potential of time-resolved laser induced fluorescence spectroscopy (TR-LIFS) as intra-operative tool for the delineation of brain tumor from normal brain. Forty two patients undergoing glioma (WHO grade I-IV) surgery were enrolled in this study. A TR-LIFS prototype apparatus (gated detection, fast digitizer) was used to induce in-vivo fluorescence using a pulsed N2 laser (337 nm excitation, 0.7 ns pulse width) and to record the time-resolved spectrum (360-550 nm range, 10 nm interval). The sites of TR-LIFS measurement were validated by conventional histopathology (H&E staining). Parameters derived from the TR-LIFS data including intensity values and time-resolved intensity decay features (average fluorescence lifetime and Laguerre coefficients values) were used for tissue characterization and classification. 71 areas of tumor and normal brain were analyzed. Several parameters allowed for the differentiation of distinct tissue types. For example, normal cortex (N=35) and normal white matter (N=12) exhibit a longer-lasting fluorescence emission at 390 nm (τ390=2.12±0.10 ns) when compared with 460 nm (τ460=1.16±0.08 ns). High grade glioma (grades III and IV) samples (N=17) demonstrate emission peaks at 460 nm, with large variation at 390 nm while low grade glioma (I and II) samples (N=7) demonstrated a peak fluorescence emission at 460 nm. A linear discriminant algorithm allowed for the classification of low-grade gliomas with 100% sensitivity and 98% specificity. High-grade glioma demonstrated a high degree of heterogeneity thus reducing the discrimination accuracy of these tumors to 47% sensitivity and 94% specificity. Current findings demonstrate that TR-LIFS holds the potential to diagnose brain tumors intra-operatively and to provide a valuable tool for aiding the neurosurgeon-neuropathologist team in to rapidly distinguish between tumor and normal brain during surgery.
NeuroImage 11/2010; 54 Suppl 1:S125-35. · 5.89 Impact Factor
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ABSTRACT: Homeless men who have sex with men are a particularly vulnerable population with high rates of substance dependence, psychiatric disorders, and HIV prevalence. Most need strong incentives to engage with community-based prevention and treatment programs. Contingency management (CM) was implemented in a community HIV prevention setting and targeted reduced substance use and increased health-promoting behaviors over a 24-week intervention period. Participants in the CM condition achieved greater reductions in stimulant and alcohol use (χ(2) = 27.36, p < .01) and, in particular, methamphetamine use (χ(2) = 21.78, p < .01) and greater increases in health-promoting behaviors (χ(2) = 37.83, p < .01) during the intervention period than those in the control group. Reductions in substance use were maintained to 9- and 12-month follow-up evaluations. Findings indicate the utility of CM for this high-risk population and the feasibility of implementing the intervention in a community-based HIV prevention program.
Journal of substance abuse treatment 10/2010; 39(3):255-63. · 2.90 Impact Factor
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ABSTRACT: Homeless, substance-dependent men who have sex with men (MSM) continue to suffer health disparities, including high rates of HIV. One-hundred and thirty one homeless, substance-dependent MSM were randomized into a contingency management (CM) intervention to increase substance abstinence and health-promoting behaviors. Participants were recruited from a community-based, health education/risk reduction HIV prevention program and the research activities were also conducted at the community site. Secondary analyses were conducted to identify and characterize treatment responders (defined as participants in a contingency management intervention who scored at or above the median on three primary outcomes). Treatment responders were more likely to be Caucasian/White (p < .05), report fewer years of lifetime methamphetamine, cocaine, and polysubstance use (p < or = .05), and report more recent sexual partners and high-risk sexual behaviors than nonresponders (p < .05). The application of evidence-based interventions continues to be a public health priority, especially in the effort to implement effective interventions for use in community settings. The identification of both treatment responders and nonresponders is important for intervention development tailored to specific populations, both in service programs and research studies, to optimize outcomes among highly impacted populations.
Journal of psychoactive drugs 44(2):166-72. · 1.10 Impact Factor
