• Investigative Magnetic Resonance Imaging
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• v.3 no.1
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• pp.47-52
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• 1999

Purpose : The purpose of this study was aimed to evaluate the BOLD(blood oxygen level dependent) contrast fMRI(functional MR imaging) in the occipital lobe and to compare with the metabolic changes based on H MRS (MR spectroscopy) and MRSI (MR spectroscopic imaging) before and after visual stimulation Materials and Methods : Healthy human volunteers (eight males and two females with 24-30 year age) participated in this study. All of the BOLD fMRI were acquired on a 1.5T MR with EPI during supervised visual stimulation in the occipital lobe. The red flicker with 8Hz was used for visual stimulation. After imaging acquisition, the MR images were transferred into unix workstation and processed with acquired from the same location based on the activation map. MRSI (magnetic resonance spectroscopic imaging) was also acquired to analyze the lactate changes before and after stimulation. Results : The activation maps were successfully produced by BOLD effect due to visual stimulation. NAA (N-acetyle aspartate)/Cr (creatine) ratio varied only from $1.79{\pm}0.28{\;}to{\;}1.88{\pm}0.20$ in activation area before and after stimulation. However, the signal intensity of lactate was elevated $9.48{\pm}4.38$ times higher than before activation. Lactate metabolite images were consistent with the activation maps. Conclusion : The BOLD contrast fMRI is enough sensitive to detect the activated area in human brain during the visual stimulation. Lactate metabolite map presents the evidence of lactate elevation on the same area of activation.

• Korean Journal of Food Science and Technology
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• v.33 no.5
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• pp.567-573
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• 2001

Lactobacilli have been generally recognized as an important lactic acid bacteria present in the normal human intestinal flora. Fifty two Lactobacillus isolates were recovered from the feces of healthy Koreans whose age ranged from thirteen days after birth to 37 years. Among the isolates above, 17 isolates were tentatively identified as strains of Lactobacillus acidophilus and 3 isolates as strains of Lactobacillus casei. For their characterization, these twenty isolates were subjected to the experiments for the resistance to the artificial gastric juice, pH2.5 and bile salt. Interestingly, 3 strains survived pH 2.5 after 3 hour incubation in the artificial gastric juice with more than 75% of survival rate. L. acidophilus a-4 had the highest survival rate of 100%. Four strains including L. acidophilus a-3 grew gradually in MRS broth in the presence of the artificial bile salt. Cholesterol assimilation was also tested for the 20 isolates. The result showed that cholesterol concentration of the medium was reduced by 10 Lactobacillus isolates with more than 60%, as compared to the control. L. acidophilus a-2 had the highest reduction rate of 77%. Judging from these data obtained in vitro, some isolates ware likely to reach the lower small intestine after consumption without a significant loss of viability, suggesting that they had the potential to be developed as a probiotic culture which might lower the cholesterol level in human.