Associations between markers of colorectal cancer stem cells and adenomas among ethnic groups.

BACKGROUND AND PURPOSES: Most colorectal tumors develop from adenomatous polyps, which are detected by colonoscopy. African Americans (AAs) have higher incidence of colorectal cancer (CRC) and greater mortality from this disease than Caucasian Americans (CAs). We investigated whether differences in predisposition to CRC and its surrogate (colonic adenomas) between these ethnic groups were related to numbers of cancer stem or stem-like cells (CSCs) in colonocytes. METHODS: We analyzed colonic effluent from 11 AA and 14 CA patients who underwent scheduled colonoscopy examinations at the John D. Dingell Veterans Affairs Medical Center. We determined proportions of cells that expressed the CSC markers CD44 and CD166 by flow cytometry. RESULTS: The proportion of colonocytes that were CD44(+)CD166(-) in effluent from patients with adenomas was significantly greater than from patients without adenomas (P = 0.01); the proportion of CD44(+)CD166(+) colonocytes was also greater (P = 0.07). Effluent from AAs with adenomas had 60 % more CD44(+)166(-) colonocytes than from CAs with adenomas. Using cutoff values of 8 % for AAs and 3 % for CAs, the proportion of CD44(+)166(-) colonocytes that had positive predictive value for detection of adenomas was 100 % for AAs and CAs, determined by receiver operator characteristic curve analysis. CONCLUSION: The proportion of CD44(+)166(-) colonocytes in colonic effluent can be used to identify patients with adenoma. AAs with adenomas have a higher proportion of CD44(+)166(-) colonocytes than CA. The increased proportion of CSCs in colonic tissue from AA might be associated with the increased incidence of CRC in this population.

Gamma butyrolactone (GBL) and gamma valerolactone (GVL): similarities and differences in their effects on the acoustic startle reflex and the conditioned enhancement of startle in the rat.

Gamma butyrolactone (GBL) is metabolized to gamma hydroxybutyrate (GHB) in the body. GHB is a DEA Schedule 1 compound; GBL is a DEA List 1 chemical. Gamma valerolactone (GVL) is the 4-methyl analog of GBL; GVL is metabolized to 4-methyl-GHB; GVL is NOT metabolized to GBL or GHB. The effects of GBL (18.75-150 mg/kg), GVL (200-1600 mg/kg) or vehicle on the acoustic startle reflex (ASR), and the classically-conditioned enhancement of startle, the Startle Anticipated Potentiation of Startle (SAPS) response were studied in male rats. Both compounds produced a dose-dependent reduction of ASR, with GBL 5-7 times more potent than GVL. In contrast, GBL treatment significantly reduced SAPS at doses that exerted only moderate effects on ASR, whereas GVL exerted little or no effect on the SAPS, except at doses that produced pronounced reductions in Noise Alone ASR. In a second experiment, rats were tested for Noise Alone ASR behavior following treatment with a single mid-range dose of GBL (75 mg/kg), GVL (400mg/kg) or vehicle; immediately following startle testing the animals were sacrificed and their brains and blood were collected for determination of GHB, 4-methyl-GHB, GBL and GVL. GHB was found in measurable concentrations in all of the blood specimens and 6 (of 8) of the brain specimens from the GBL-treated subjects. 4-Methyl-GHB was found in measurable concentrations in all of the blood and brain specimens of the GVL-treated subjects; the change in startle amplitude was inversely correlated to the brain concentrations of these compounds. These findings confirm the differences in the metabolic fate of GBL and GVL as pro-drugs for the formation of GHB and 4-methyl-GHB, respectively. Moreover, the dissimilarity in effect profile for GBL and GVL on ASR versus SAPS behaviors suggests that different receptor(s) may be involved in mediating these behavioral effects.

Effects of buspirone and alprazolam treatment on the startle-potentiated startle response.

The startle potentiated startle (SPS) paradigm has been reported to be an effective procedure for studying the conditioned enhancement of acoustic startle in the absence of electric shocks or extinction. This study examines the effects of two anxiolytic treatments, buspirone and alprazolam, on this SPS effect. Subjects were tested in the SPS paradigm 2 days a week (Monday and Thursday) for 10 weeks. Each startle test session consisted of 10 Noise Alone trials (115 dB acoustic noise burst presented for 40 ms) and 10 Light+Noise trials (115 dB acoustic stimuli presented during the latter 40 ms of a 3,540 ms period in which a 15-watt light was illuminated). Although there was no difference in startle amplitude on Noise Alone trials when compared to Light+Noise trials initially, by the end of the first test session and continuing throughout the duration of the experiment, startle amplitude on Light+Noise trials was significantly (approximately 50-75%) greater than on Noise Alone trials. After five control (i.e., no injection) SPS test sessions, once-weekly drug challenges were conducted over the course of 7 weeks. In these weekly drug challenges, subjects received acute treatment with various doses of the benzodiazepine anxiolytic alprazolam (0.25, 0.5, 1.0 mg/kg) or the novel anxiolytic buspirone (1.0, 2.0, 4.0 mg/kg); subjects also received vehicle treatment (0.5% methylcellulose) on one treatment day. All treatments were administered intraperitoneally (i.p.), 15 min before the start of startle testing. Consistent with previous reports, buspirone increased and alprazolam decreased startle amplitude on the Noise Alone trials; these effects were dose-related. Both agents reduced the magnitude of the SPS effect when it was expressed as the Light+Noise startle amplitude minus the Noise Alone startle amplitude. These findings are similar to the effects of these treatments in the traditional shock-based fear-potentiated startle paradigm.