Higher-order least squares: assessing partial goodness of fit of linear causal models

We introduce a simple diagnostic test for assessing the overall or partial goodness of fit of a linear causal model with errors being independent of the covariates. In particular, we consider situations where hidden confounding is potentially present. We develop a method and discuss its capability to distinguish between covariates that are confounded with the response by latent variables and those that are not. Thus, we provide a test and methodology for partial goodness of fit. The test is based on comparing a novel higher-order least squares principle with ordinary least squares. In spite of its simplicity, the proposed method is extremely general and is also proven to be valid for high-dimensional settings.</p

Increased levels of deleted mitochondrial DNA in aged retinal pigment epithelium and choroid

Measurements of levels of the PCR products of non-deleted (, not damaged) and deleted (, damaged) mitochondrial DNA (mtDNA) normalized by total mtDNA normalized by total mtDNA were done using the PicoGreen reagent. Each PCR reaction started with 10 ng of genomic DNA (nuclear and mitochondrial) from rat retinal pigment epithelium (RPE) and choroid as a template. There was no difference in the non-deleted mtDNA at 18 month (p=0.02, n=5), 24 month (p=0.06, n=5), and 32 month (p=0.70, n=5), compared with the 4 month group. However, there was a significant increase in deleted mtDNA at 18 month (p=0.003, n=5), 24 month (p<p><b>Copyright information:</b></p><p>Taken from "Increased mitochondrial DNA damage and down-regulation of DNA repair enzymes in aged rodent retinal pigment epithelium and choroid"</p><p></p><p>Molecular Vision 2008;14():644-651.</p><p>Published online 04 Apr 2008</p><p>PMCID:PMC2288587.</p><p></p

Targeting High Expressed α₅β₁ Integrin in Liver Metastatic Lesions To Resist Metastasis of Colorectal Cancer by RPM Peptide-Modified Chitosan-Stearic Micelles

Liver metastasis is a leading death cause in colorectal cancer. The pathological differences between orthotopic tumors and metastatic lesions increased the therapeutic difficulty of metastasis. Herein, the α₅β₁ integrin receptor expression on metastatic cells was first measured, the result showed that metastatic cells expressed the α₅β₁ integrin higher than that of the original cells from orthotopic tumors. Afterward, RPM peptide-modified chitosan-stearic (RPM-CSOSA) was designed based on α₅β₁ integrin expression. The cytotoxicity and resistance to migration and the invasion ability of the targeting drug delivery system loading doxorubicin (DOX) and curcumin (CUR) were evaluated in vitro. The metastatic inhibition of the targeting drug delivery system was also investigated in HT29 liver metastatic models. The modified RPM peptide could increase the cellular internalization of CSOSA micelles in metastatic tumor cells and endothelial cells mediated by α₅β₁ integrin. The synergistic effects of RPM-CSOSA/DOX and RPM-CSOSA/CUR could obviously inhibit migratory and invasive abilities of HT29 cells and endothelial cells. Moreover, the RPM-CSOSA/DOX&RPM-CSOSA/CUR could obviously decrease the number of metastatic sites by 86.96%, while CSOSA/DOX&CSOSA/CUR decreased liver metastasis by 66.58% compared with that in the saline group. In conclusion, the RPM peptide-modified drug delivery system may provide insights into targeting the metastatic cells overexpressing the α₅β₁ integrin, and it has the potential to inhibit liver metastasis of colorectal cancer

Lysosomal enzyme activity.

<p>(A–C) Comparison of protein levels of cathepsin D (A) and β-glucuronidase (B) in ARPE-19 cells by immunoblots. β-actin was used as a loading control (C). (D) Expression of cathepsin D in ARPE-19 cells. The differences in protein levels of cathepsin D were determined by scanning gels and determining the integrated areas of the bands using Image-J software. Data are expressed as normalized ratios to actin. Appropriate background subtraction and normalization of the data to actin was done for each blot. Values are the mean±SEM. There were significant increases in cathepsin D protein following 10 µM B(a)P treatment for 24 hr and 48 hr (p<0.05, n = 3), compared to untreated controls. Data were expressed as normalized ratios to actin. (E) Expression of β-glucuronidase in ARPE-19 cells. The differences in expression levels of β-glucuronidase were determined by scanning gels and determining the integrated areas of the bands using Image-J software. Data are expressed as normalized ratios to actin. Appropriate background subtraction and normalization of the data to actin was done for each blot. Values are the mean±SEM. There were significant increases in β-glucuronidase protein following 10 µM B(a)P treatment for 24 hr and 48 hr (p<0.05, n = 3), compared to untreated controls. (F) Cathepsin D enzymatic activity from cell extracts were significantly increased at 10 µM B(a)P treatment (<i>p</i><0.05, n = 3). (<i>G</i>) β-glucuronidase enzymatic activity from cell extracts was significantly increased at 10 µM B(a)P treatment (<i>p</i><0.05, n = 3).</p

Exosome markers and complement in ARPE-19 cells.

<p>(<i>A</i>) When the cells were treated with 10 µM B(a)P for 24 hr to damage their mtDNA, gene expression of exosome markers CD63, CD81 and LAMP2 was significantly increased at 24 hrs (<i>p</i><0.05, n = 3). (<i>B</i>) When the cells were treated with 10 µM B(a)P for 24 hr to damage their mtDNA, gene expression of complement pathway components CFH, C3, CFB and CD59 was significantly increased at 24 hrs (p<0.05, n = 3).</p

TCS1, a Microtubule-Binding Protein, Interacts with KCBP/ZWICHEL to Regulate Trichome Cell Shape in <i>Arabidopsis thaliana</i>

<div><p>How cell shape is controlled is a fundamental question in developmental biology, but the genetic and molecular mechanisms that determine cell shape are largely unknown. Arabidopsis trichomes have been used as a good model system to investigate cell shape at the single-cell level. Here we describe the <i>trichome cell shape 1</i> (<i>tcs1</i>) mutants with the reduced trichome branch number in Arabidopsis. <i>TCS1</i> encodes a coiled-coil domain-containing protein. Pharmacological analyses and observations of microtubule dynamics show that TCS1 influences the stability of microtubules. Biochemical analyses and live-cell imaging indicate that TCS1 binds to microtubules and promotes the assembly of microtubules. Further results reveal that TCS1 physically associates with KCBP/ZWICHEL, a microtubule motor involved in the regulation of trichome branch number. Genetic analyses indicate that <i>kcbp/zwi</i> is epistatic to <i>tcs1</i> with respect to trichome branch number. Thus, our findings define a novel genetic and molecular mechanism by which TCS1 interacts with KCBP to regulate trichome cell shape by influencing the stability of microtubules.</p></div

Phagocytic activity of ARPE-19 cells.

<p>B(a)P at concentrations in the media of 2.5–20 µM did not change phagocytic activity when cells were exposed to fluorescein labeled bovine photoreceptor outer segments for 3 hr (p>0.05, n = 4).</p

Cell viability assay for ARPE-19 cells treated with B(a)P.

<p>Concentrations in the media of 1.25 to 20 µM of B(a)P did not cause a significant decrease of cell viability (p>0.05, n = 10). Data are expressed as normalized ratios (Control = 100).</p

Transmission electron microscopy of the RPE-Bruch's membrane.

<p>A. Control, mice exposed to air (n = 5). This representative micrograph shows that mitochondrial membrane and cristae were well preserved and the matrix has homogeneous electron-dense (arrows). B. Mice exposed to cigarette smoke (n = 5). This representative micrograph shows that mitochondria had lost outer membrane and there was disorganization of cristae (arrows). C. Control, mice exposed to air. This representative micrograph at high power shows intact outer membranes of mitochondria. D. Mice exposed to cigarette smoke. This representative micrograph at high power shows loss of mitochondrial outer membranes (arrows) and disorganization of the cristae (arrowhead). A, B: Scale bar = 1 µm; C, D: scale bar = 500 nm.</p