Comparative sensitivity of microvascular endothelial cells, fibroblasts and tumor cells after in vitro photodynamic therapy with meso-tetra-hydroxyphenyl-chlorin

The phototoxic effect of meso-tetra-hydroxyphenyl-chlorin (mTHPC)-mediated photodynamic therapy (PDT) on human microvascular endothelial cells (hMVEC) was compared with that on human fibroblasts (BCT-27) and two human tumor cell lines (HMESO-1 and HNXOE). To examine the relationship between intrinsic phototoxicity and intracellular mTHPC content, we expressed cell survival as a function of cellular fluorescence. On the basis of total cell fluorescence, HNXOE tumor cells were the most sensitive and BCT-27 fibroblasts the most resistant, but these differences disappeared after correcting for cell volume. Endothelial cells were not intrinsically more sensitive to mTHPC-PDT than tumor cells or fibroblasts. Uptake of mTHPC in hMVEC increased linearly to at least 48 h, whereas drug uptake in the other cell lines reached a maximum by 24 h. No difference in drug uptake was seen between the cell lines during the first 24 h, but by 48 h hMVEC had a 1.8- to 2.8-fold higher uptake than other cell lines. Endothelial cells showed a rapid apoptotic response after mTHPC-mediated PDT, whereas similar protocols gave a delayed apoptotic or necrotic like response in HNXOE. We conclude that endothelial cells are not intrinsically more sensitive than other cell types to mTHPC-mediated PDT but that continued drug uptake beyond 24 h may lead to higher intracellular drug levels and increased photosensitivity under certain conditions.     

Induction of tumor necrosis factor-alpha by UVB: a role for reactive oxygen intermediates and eicosanoids

UVB irradiation induces nuclear factor-kappaB (NF-kappaB) activation, tumor necrosis factor-alpha (TNF-alpha) expression and reactive oxygen intermediates (ROI) in keratinocytes. We investigated whether ROI play a role in UVB-induced TNF-alpha mRNA expression. The antioxidants N-acetyl cysteine, NAC, epigallocathin gallate, EGCG, butylated hydroxyanisole (BHA) and vitamin C could reduce UVB-induced TNF-alpha mRNA levels to various degrees; vitamin E (alpha-tocopherol) had no effect. BHA was the most potent inhibitor. The oxidant tertiary butylated hydroperoxide could effectively induce TNF-alpha mRNA expression. Nordihydroguaiaretic acid (NDGA) and MK-886, inhibitors of lipoxygenase (LOX), and indometacin and quinacrine, inhibitors of cyclooxygenase (COX) and phospholipase A2, respectively, could also reduce UVB-induced TNF-alpha mRNA expression. Inhibition by NDGA was in concordance with the results for BHA. NDGA, indometacin, quinacrine and BHA could also effectively inhibit the inhibitor of NF-kappaB degradation, thereby maintaining NF-kappaB inactivity. In conclusion, we show that ROI are implicated in the induction of TNF-alpha mRNA by UVB and that not all antioxidants are equally effective inhibitors. COX products and more importantly LOX products, which themselves are products of an oxidative metabolism, are the main ROI implicated in this induction of TNF-alpha expression by UVB probably via activation of NF-kappaB.     

Evaluation of measurement uncertainty in the determination of jasmonic acid in <Emphasis Type="Italic">Lemna minor</Emphasis> L. by liquid chromatography with fluorescence detection

The uncertainty was estimated for the determination of jasmonic acid (JA) content in Lemna minor L. plant extracts using a reverse-phase liquid chromatography with fluorescence detection. JA was extracted from plant material, followed by solid-phase extraction procedures, derivatisation and quantification. In the estimation of uncertainty, the sampling, sample processing and chromatographic determination that may significantly influence the uncertainty of analytical data were considered. The results show that the method recovery and sample homogeneity are the two main contributors to uncertainty. The method has a relative expanded uncertainty (coverage factor k = 2) of about 17% at the JA content of approximately 100 ng/g.     

The Donor-Dependent and Colon-Region-Dependent Metabolism of (+)-Catechin by Colonic Microbiota in the Simulator of the Human Intestinal Microbial Ecosystem

The intestinal absorption of dietary catechins is quite low, resulting in most of them being metabolized by gut microbiota in the colon. It has been hypothesized that microbiota-derived metabolites may be partly responsible for the association between catechin consumption and beneficial cardiometabolic effects. Given the profound differences in gut microbiota composition and microbial load between individuals and across different colon regions, this study examined how microbial (+)-catechin metabolite profiles differ between colon regions and individuals. Batch exploration of the interindividual variability in (+)-catechin microbial metabolism resulted in a stratification based on metabolic efficiency: from the 12 tested donor microbiota, we identified a fast- and a slow-converting microbiota that was subsequently inoculated to SHIME, a dynamic model of the human gut. Monitoring of microbial (+)-catechin metabolites from proximal and distal colon compartments with UHPLC-MS and UPLC-IMS-Q-TOF-MS revealed profound donor-dependent and colon-region-dependent metabolite profiles with 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone being the largest contributor to differences between the fast- and slow-converting microbiota and the distal colon being a more important region for (+)-catechin metabolism than the proximal colon. Our findings may contribute to further understanding the role of the gut microbiota as a determinant of interindividual variation in pharmacokinetics upon (+)-catechin ingestion.     

Local velocity measurements in a thermally-stratified sodium mixing layer using a permanent-magnet probe

Mean and fluctuating velocities have been measured in a sodium mixing layer experiment, i.e. in a fluid with very low Prandtl number (Pr10⁻²), with a miniature permanent-magnet velocity probe in the presence of strong temperature gradients. A mathematical model for the probe, based upon Faraday's law of induction and including thermoelectric as well as inertia effects due to the finite response time of thermocouples, is presented together with a new dynamic method to compensate for these effects. The sensitivity of the four different probes used in this experiment is in the range of 81–65 (μV/ms⁻¹). Electrical pertubations arising from large-scale thermoelectric effects inside the test section and their influence on the velocity signal are also discussed. The electronic measurement system, combining low noise and high resolution, was specially developed to match the experimental requirements. With this system it was possible to measure velocity RMS-values down to 1 mm/s corresponding to a voltage of 100 nV, and mean velocities with an accuracy of about 6 mm/s. This paper deals with the peculiarities of the measurement technique and its performance, but does not analyze the experimental results, which will be presented in a separate publication.     

Extending Time Profile of Morphine‐Induced Analgesia Using a Chitosan‐Based Molecular Imprinted Polymer Nanogel

Chitosan‐based molecular imprinted polymer (CS‐MIP) nanogel is prepared in the presence of morphine template, fully characterized and used as a new vehicle to extend duration of morphine analgesic effect in Naval Medical Research Institute mice. The CS‐MIP nanogel with ≈25 nm size range exhibits 98% loading efficiency, and in vitro release studies show an initial burst followed by an extended slow release of morphine. In order to study the feasibility of CS‐MIP nanogel as morphine carrier, 20 mice are divided into two groups randomly and received subcutaneous injection of morphine‐loaded CS‐MIP and morphine (10 mg kg^?1) dissolved in physiologic saline. Those received injection of morphine‐loaded CS‐MIP show slower and long lasting release of morphine with 193 min effective time of 50% (ET50) analgesia compared to 120 min ET50 in mice received morphine dissolved in physiologic saline. These results suggest that CS‐MIP nanogel can be a possible strategy as morphine carrier for controlled release and extension of its analgesic efficacy.

     

Conformational study of a strained tolanophane by dynamic 1H NMR spectroscopy and computational methods

The existence of a short C–H ⋯ π (alkyl–alkyne) interaction in the structure of a strained and relatively rigid tolanophane is expected to hinder the rotation about the C–C sp³ single bond. Variable-temperature NMR experiments (performed in three solvents, CDCl₃, THF-d₈, and acetone-d₆) and ab initio density functional calculations were carried out to investigate its dynamic nature. An energy barrier of 48.6 kJ/mol is determined at coalescence (210 K) with acetone-d₆ which is in good agreement with calculation result (54 kJ/mol). Correspondence: Hossein Reza Darabi, Chemistry and Chemical Engineering Research Center of Iran, Pajoohesh Blvd., km 17, Karaj Hwy, 14968-13151 Tehran, Iran.     

From laser-induced line narrowing to electro- magnetically induced transparency: closed system analysis

The laser-induced line-narrowing effect, discovered more than thirty years ago, can also be applied to recent studies in high resolution spectroscopy based on electromagnetically induced transparency. In this paper we first present a general form of the transmission width of electromagnetically induced transparency in a homogeneously broadened medium. We then analyze a Doppler broadened medium by using a lorentzian function as the atomic velocity distribution. The dependence of the transmission linewidth on the driving field intensity is discussed and compared to the laser-induced line-narrowing effect. This dependence can be characterized by a parameter which can be regarded as “the degree of optical pumping.” Received: 17 December 2001 / Published online: 15 January 2003 RID="*" ID="*"Corresponding author. E-mail: hwang.Lee@jpl.nasa.gov RID="**" ID="**"Present address: Jet Propulsion Laboratory, MS 126-347, California Institute of Technology, Pasadena, CA 91109, USA