An analytical representation of raindrop size distribution in a mixed convective and stratiform precipitating system as revealed by field observations

This study investigated a rainfall event under a typhoon influence using a 2D video disdrometer and weather radar observations to characterize raindrop size distribution (DSD) in a mixed convective and stratiform precipitating system. During the time period when both convective and stratiform rainfalls existed, the DSDs generally indicated a monotonically decreasing shape with increasing particle size, with a relatively gradual decrease at intermediate particle size observed at certain times; this feature is attributed to the combined effect of convective and stratiform rainfalls. During the transitional period between convective and stratiform rainfalls, the DSDs exhibited a bimodal shape. The DSDs were well approximated by a newly proposed gamma raindrop distribution combined with exponential (GRACE) distribution function, which was defined as the sum of the exponential distribution and the gamma distribution. A comparison of the volume ratio of the exponential and gamma components of the GRACE distribution revealed that the exponential component of the DSD was larger than the gamma component in the bimodal DSD. These results suggest that the DSD became bimodal during the period when stratiform rainfall predominated because of the weakening of convective rainfall. The GRACE distribution is useful for understanding cloud-microphysical processes in mixed stratiform and convective precipitation conditions

From Supermembrane to Matrix String

We develop a systematic method of directly embedding supermembrane wrapped around a circle into matrix string theory. Our purpose is to study connection between matrix string and membrane from an entirely 11 dimensional point of view. The method does neither rely upon the DLCQ limit nor upon string dualities. In principle, this enables us to construct matrix string theory with arbitrary backgrounds from the corresponding supermembrane theory. As a simplest application of the formalism, the matrix-string action with a 7 brane background (Kaluza-Klein Melvin solution) with nontrivial RR vector field is given.Comment: 36 pages, 1 figur

Melatonin suppression during a simulated night shift in medium intensity light is increased by 10-minute breaks in dim light and decreased by 10-minute breaks in bright light

Exposure to light at night results in disruption of endogenous circadian rhythmicity and/or suppression of pineal melatonin, which can consequently lead to acute or chronic adverse health problems. In the present study, we investigated whether exposure to very dim light or very bright light for a short duration influences melatonin suppression, subjective sleepiness, and performance during exposure to constant moderately bright light. Twenty-four healthy male university students were divided into two experimental groups: Half of them (mean age: 20.0 +/- 0.9 years) participated in an experiment for short-duration (10 min) light conditions of medium intensity light (430 lx, medium breaks) vs. very dim light (< 1 lx, dim breaks) and the other half (mean age: 21.3 +/- 2.5 years) participated in an experiment for short-duration light conditions of medium intensity light (430 lx, medium breaks) vs. very bright light (4700 lx, bright breaks). Each simulated night shift consisting of 5 sets (each including 50-minute night work and 10-minute break) was performed from 01:00 to 06:00 h. The subjects were exposed to medium intensity light (550 lx) during the night work. Each 10-minute break was conducted every hour from 02:00 to 06:00 h. Salivary melatonin concentrations were measured, subjective sleepiness was assessed, the psychomotor vigilance task was performed at hourly intervals from 21:00 h until the end of the experiment. Compared to melatonin suppression between 04:00 and 06:00 h in the condition of medium breaks, the condition of dim breaks significantly promoted melatonin suppression and the condition of bright breaks significantly diminished melatonin suppression. However, there was no remarkable effect of either dim breaks or bright breaks on subjective sleepiness and performance of the psychomotor vigilance task. Our findings suggest that periodic exposure to light for short durations during exposure to a constant light environment affects the sensitivity of pineal melatonin to constant light depending on the difference between light intensities in the two light conditions (i.e., short light exposure vs. constant light exposure). Also, our findings indicate that exposure to light of various intensities at night could be a factor influencing the light-induced melatonin suppression in real night work settings

A Novel Splicing Variant of Peroxisome Proliferator-Activated Receptor-γ (<i>Pparγ1sv</i>) Cooperatively Regulates Adipocyte Differentiation with <i>Pparγ2</i>

<div><p>Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that regulate expression of a number of genes associated with the cellular differentiation and development. Here, we show the abundant and ubiquitous expression of a newly identified splicing variant of mouse <i>Pparγ</i> (<i>Pparγ1sv</i>) that encodes PPARγ1 protein, and its importance in adipogenesis. The novel splicing variant has a unique 5′-UTR sequence, relative to those of <i>Pparγ1</i> and <i>Pparγ2</i> mRNAs, indicating the presence of a novel transcriptional initiation site and promoter for <i>Pparγ</i> expression. <i>Pparγ1sv</i> was highly expressed in the white and brown adipose tissues at levels comparable to <i>Pparγ2</i>. <i>Pparγ1sv</i> was synergistically up-regulated with <i>Pparγ2</i> during adipocyte differentiation of 3T3-L1 cells and mouse primary cultured preadipocytes. Inhibition of <i>Pparγ1sv</i> by specific siRNAs completely abolished the induced adipogenesis in 3T3-L1 cells. C/EBPβ and C/EBPδ activated both the <i>Pparγ1sv</i> and <i>Pparγ2</i> promoters in 3T3-L1 preadipocytes. These findings suggest that <i>Pparγ1sv</i> and <i>Pparγ2</i> synergistically regulate the early stage of the adipocyte differentiation.</p></div

Ezetimibe Promotes Brush Border Membrane-to-Lumen Cholesterol Efflux in the Small Intestine

<div><p>Ezetimibe inhibits Niemann-Pick C1-like 1 (NPC1L1), an apical membrane cholesterol transporter of enterocytes, thereby reduces intestinal cholesterol absorption. This treatment also increases extrahepatic reverse cholesterol transport via an undefined mechanism. To explore this, we employed a trans-intestinal cholesterol efflux (TICE) assay, which directly detects circulation-to-intestinal lumen ³H-cholesterol transit in a cannulated jejunal segment, and found an increase of TICE by 45%. To examine whether such increase in efflux occurs at the intestinal brush border membrane(BBM)-level, we performed luminal perfusion assays, similar to TICE but the jejunal wall was labelled with orally-given ³H-cholesterol, and determined elevated BBM-to-lumen cholesterol efflux by 3.5-fold with ezetimibe. Such increased efflux probably promotes circulation-to-lumen cholesterol transit eventually; thus increases TICE. Next, we wondered how inhibition of NPC1L1, an influx transporter, resulted in increased efflux. When we traced orally-given ³H-cholesterol in mice, we found that lumen-to-BBM ³H-cholesterol transit was rapid and less sensitive to ezetimibe treatment. Comparison of the efflux and fractional cholesterol absorption revealed an inverse correlation, indicating the efflux as an opposite-regulatory factor for cholesterol absorption efficiency and counteracting to the naturally-occurring rapid cholesterol influx to the BBM. These suggest that the ezetimibe-stimulated increased efflux is crucial in reducing cholesterol absorption. Ezetimibe-induced increase in cholesterol efflux was approximately 2.5-fold greater in mice having endogenous ATP-binding cassette G5/G8 heterodimer, the major sterol efflux transporter of enterocytes, than the knockout counterparts, suggesting that the heterodimer confers additional rapid BBM-to-lumen cholesterol efflux in response to NPC1L1 inhibition. The observed framework for intestinal cholesterol fluxes may provide ways to modulate the flux to dispose of endogenous cholesterol efficiently for therapeutic purposes.</p></div

Effect of knock-down of <i>Pparγ1sv</i> on adipogenesis of 3T3-L1 cells.

<p>(A) Locations of the targeting sites of siRNAs for <i>Pparγ1sv</i>, <i>Pparγ2</i>, and both transcripts (common). For the validation of siRNAs using a luciferase reporter gene, the full-length <i>Pparγ1sv</i> or <i>Pparγ2</i> cDNA was inserted into <i>Xho</i> I site in pGL3-Control in sense or antisense direction. (B) Evaluation of siRNAs for <i>Pparγ1sv</i> or <i>Pparγ2</i>. 3T3-L1 cells were transfected with each of siRNA, and subjected to adipogenic induction in the following day (day 0). Expression of PPARγ1 and PPARγ2 proteins at day 2 was detected using PPARγ antibody with Lamin B1 as a control for nuclear extracts. siControl is negative control siRNA. Arrows indicate the positions of PPARγ1 and PPARγ2 proteins. (C) Validation of siRNA specificity. The relative luciferase activities were obtained from 3T3-L1 cells 1 day after transfection with pGL3-Control containing the <i>Pparγ1sv</i> or <i>Pparγ2</i> cDNA in sense or antisense direction and each of two respective siRNAs for <i>Pparγ1sv</i> and <i>Pparγ2</i>. The values represent the mean of triplicate measurements. The activity of siControl cells is defined as 100%. (D) 3T3-L1 cells transfected with siRNAs were subjected to adipogenic induction and stained by Oil Red O at day 9. Microscopic (x100) observations are shown. (E) Quantitative measurement of intracellular triglycerides in siRNA knock-down cells at days 0 and 6 using AdipoRed reagent. Data represent the mean of 4 replicate assays. *<i>P</i><0.01 compared to siControl cells at day 6. (F) Protein expression levels of PPARγ, C/EBPβ, C/EBPα, Lamin B1 (control for nuclear extracts), FABP4 (aP2), DLK (pref-1), and α-tubulin (control for cytosolic extracts) in <i>Pparγ1sv</i> or <i>Pparγ2</i> knock-down cells at days 2 and 6 detected by the corresponding antibodies.</p

Cholesterol efflux in ABCG5 and ABCG8 double knockout (DKO) mice.

<p><i>A</i>, Quantitative RT-PCR showed that <i>NPC1L1</i> gene expression level did not differ apparently with ABCG5/G8 deletions in mice. Gene expressions were normalized against <i>18s</i> expression levels. Then the relative expression levels were compared between the two genotypes, WT (n 10) and ABCG5/G8 DKO (n 6) with the levels in the WT mice as the references. Data are shown as mean ± SEM. <i>B</i>, Ezetimibe (50 μg)-induced increase in cholesterol efflux was partially abolished in ABCG5/G8 DKO mice. <i>Upper</i>, Plots for ³H-decay per minute (DPM) counts in the perfusate (<i>right</i>, <i>gray circles</i>) and the perfused intestinal segment (<i>left</i>, <i>open circles</i>). <i>Lower</i>; ³H-DPM in the perfusate was divided by that in the intestinal segment perfused to obtain a ratio (%), which was then converted to a common logarithm. Bars indicate medians. The difference between wild-type (WT) and DKO mice was compared using the Student’s <i>t</i>-test. Each plot shows an individual assay result. Alphabetical differences (in parentheses) indicate significant difference between the groups (<i>p</i> < 0.05) using Tukey's Honestly Significant Difference test. <i>C</i>, ABCG5/G8 DKO partially abolished the inhibitory effect of ezetimibe on the intestinal cholesterol transit. Bars indicate medians. Each plot shows an individual assay result. The difference between the WT and the DKO mice was compared using the Mann—Whitney <i>U</i>-test. <i>D</i>, Comparison of mRNA abundance by quantitative RT-PCR between the jejunal samples of C57BL/6J and 129^<i>+Ter</i>/SvJ. Data are shown as mean ± SEM (n 5). <i>E</i>, Characteristic comparisons of C57BL/6J and 129^<i>+Ter</i>/SvJ mice in luminal perfusion assay. <i>Upper</i>, efflux efficiency; <i>lower</i>, intestinal ³H-DPM abundance. The difference between the two strains was compared using the Mann—Whitney <i>U</i>-test. Bars indicate medians. Each plot shows an individual assay result.</p

Cholesterol enters HepG2 and differentiated Caco-2 cells by NPC1L1-independent manner mainly.

<p><i>A</i>, (a) Transient overexpression of NPC1L1 in the plasma membranes examined by Western blotting analysis. <i>Upper</i>, QuickBlue staining; <i>lower</i>, immunostaining for NPC1L1. (b) ABCG5 (<i>upper</i>) and ABCG8 (<i>lower</i>) protein expressions in HepG2 cells. <i>Insets</i>, these two images were adjusted to increase visibility of the bands. <i>B</i>, Medium-to-cell cholesterol transit in HepG2 cells. Transfection and ezetimibe treatment were performed as indicated as shown in the bottom. Medium-to-cell ³H-cholesterol transit efficiency (%) was estimated as described in the “Materials and Methods”. Each plot shows an individual assay result. Bars indicate means. Alphabetical differences among the groups (in parentheses) indicate significant difference between the groups (<i>p</i> < 0.05) using Tukey's Honestly Significant Difference test. <i>C</i>, Cholesterol (<i>upper</i>) and protein (<i>lower</i>) abundance in HepG2 cells. No significant difference was observed among the groups using Tukey's Honestly Significant Difference test. Bars show mean ± SEM (<i>n</i> = 4). <i>D</i>, (a) An illustration of Caco-2 cell culture system used in this study. Caco-2 cells were grown on filter membranes to allow the development to an enterocyte-like phenotype (see text for the detailed methods). The supernatants in culture inserts and wells were designated as apical and basolateral media, respectively. Lipid micelles were added to the apical medium. (b) Absorptive epithelial cell morphology of differentiated Caco-2 cell monolayers with a cylinder-like cell shape, the development of microvilli, and the distal localization of nuclei demonstrated by an electron microscopic analysis. (c) NPC1L1 was localized to the apical membrane in differentiated Caco-2 cells. Confocal microscopic analysis showed that NPC1L1 colored in <i>green</i> was localized to the plasma membrane (the upper image), especially in the brush border area (the lower image). 7-amino-actinomycin D was used for counterstaining of nuclei (<i>red</i>). <i>E</i>, Ezetimibe had little effect on medium-to-cell ³H-cholesterol transit in differentiated Caco-2 cells. <i>Open circles</i>, vehicle (1% ethanol); <i>closed circles</i>, 50 μmol/l ezetimibe. Data were shown as mean ± SEM of triplicate assays. <i>F</i>, In contrast to human duodenum (a) and murine jejunum (b), the gene expressions of <i>ABCG5</i> and <i>ABCG8</i> were absent in differentiated Caco-2 cells (c). Gene expression levels of five major membrane sterol transporters were analyzed by quantitative RT-PCR. An RNA sample of human duodenum was assayed in triplicate. Murine jejunal RNA samples were obtained from three C57BL/6J mice and assayed in duplicate. Three separate total RNA samples were obtained from independent wells of differentiated Caco-2 cells and assayed in duplicate. Data were shown as mean ± SEM of analytical triplicate (a) or biological triplicate (b, c) assays.</p

Gene and cDNA structures of the novel splicing variant of mouse <i>Pparγ</i>.

<p>(A) Alignment of 5′-end sequences of <i>Pparγ1sv</i>, <i>Pparγ1</i>, and <i>Pparγ2</i> cDNAs. Each initiation codon is outlined, and exon 1, which is common to all three, is underlined. (B) Gene structure of N-terminal exons and common exon 1 of mouse <i>Pparγ</i> on chromosome 6. Distances between two exons and exon lengths are indicated as numbers of nucleotides. Arrows indicate the positions of the transcription initiation site of each transcription variant. (C) Multiple alignment of nucleotide sequences of mouse exon C and corresponding exons in other mammals. Distances between the 5′-end of each cDNA and exon C or corresponding exons of other mammals are indicated as numbers of base pairs.</p