Showing papers by "University of Texas Southwestern Medical Center published in 2002"
TL;DR: The complex, interdigitated roles of these three SREBPs have been dissected through the study of ten different lines of gene-manipulated mice and form the subject of this review.
Abstract: Lipid homeostasis in vertebrate cells is regulated by a family of membrane-bound transcription factors designated sterol regulatory element–binding proteins (SREBPs). SREBPs directly activate the expression of more than 30 genes dedicated to the synthesis and uptake of cholesterol, fatty acids, triglycerides, and phospholipids, as well as the NADPH cofactor required to synthesize these molecules (1–4). In the liver, three SREBPs regulate the production of lipids for export into the plasma as lipoproteins and into the bile as micelles. The complex, interdigitated roles of these three SREBPs have been dissected through the study of ten different lines of gene-manipulated mice. These studies form the subject of this review.
4,406 citations
TL;DR: A neurobiologic understanding of depression also requires identification of the genes that make individuals vulnerable or resistant to the syndrome, and advances will fundamentally improve the treatment and prevention of depression.
2,768 citations
Emory University1, Research Triangle Park2, Case Western Reserve University3, National Institutes of Health4, University of Alabama at Birmingham5, Yale University6, Indiana University7, University of Cincinnati8, Boston Children's Hospital9, University of Texas Health Science Center at Houston10, Brown University11, University of Miami12, University of Tennessee Health Science Center13, Wayne State University14, University of Texas Southwestern Medical Center15, Stanford University16, University of New Mexico17
TL;DR: Infants who developed late-onset sepsis had a significantly prolonged hospital stay and were significantly more likely to die than those who were uninfected, especially if they were infected with Gram-negative organisms or fungi.
Abstract: Objective. Late-onset sepsis (occurring after 3 days of age) is an important problem in very low birth weight (VLBW) infants. To determine the current incidence of late-onset sepsis, risk factors for disease, and the impact of late-onset sepsis on subsequent hospital course, we evaluated a cohort of 6956 VLBW (401–1500 g) neonates admitted to the clinical centers of the National Institute of Child Health and Human Development Neonatal Research Network over a 2-year period (1998–2000). Methods. The National Institute of Child Health and Human Development Neonatal Research Network maintains a prospective registry of all VLBW neonates admitted to participating centers within 14 days of birth. Expanded infection surveillance was added in 1998. Results. Of 6215 infants who survived beyond 3 days, 1313 (21%) had 1 or more episodes of blood culture-proven late-onset sepsis. The vast majority of infections (70%) were caused by Gram-positive organisms, with coagulase-negative staphylococci accounting for 48% of infections. Rate of infection was inversely related to birth weight and gestational age. Complications of prematurity associated with an increased rate of late-onset sepsis included patent ductus arteriosus, prolonged ventilation, prolonged intravascular access, bronchopulmonary dysplasia, and necrotizing enterocolitis. Infants who developed late-onset sepsis had a significantly prolonged hospital stay (mean length of stay: 79 vs 60 days). They were significantly more likely to die than those who were uninfected (18% vs 7%), especially if they were infected with Gram-negative organisms (36%) or fungi (32%). Conclusions. Late-onset sepsis remains an important risk factor for death among VLBW preterm infants and for prolonged hospital stay among VLBW survivors. Strategies to reduce late-onset sepsis and its medical, social, and economic toll need to be addressed urgently.
2,102 citations
University of Texas Southwestern Medical Center1, University of Michigan2, University of Washington3, University of California, San Francisco4, University of California, Los Angeles5, University of Nebraska Omaha6, University of Pittsburgh7, Mayo Clinic8, Baylor University Medical Center9, Northwestern University10, Washington University in St. Louis11, Icahn School of Medicine at Mount Sinai12, Oregon Health & Science University13, University of Miami14, Yale University15, University of Alabama at Birmingham16, Harvard University17
TL;DR: The primary aim was to compare presenting clinical features and liver transplantation in patients with acute liver failure related to acetaminophen hepatotoxicity, other drugs, indeterminate factors, and other causes.
Abstract: Acetaminophen overdose and idiosyncratic drug reactions have replaced viral hepatitis as the most frequent causes of acute liver failure. The cause of liver failure and coma grade at admission were...
1,988 citations
Nippon Telegraph and Telephone1, Yokohama City University2, Keio University3, University of Tsukuba4, University of Queensland5, J. Craig Venter Institute6, National Institutes of Health7, Osaka University8, Novartis9, Boys Town10, Medical Research Council11, Scripps Research Institute12, University of Oregon13, Rockefeller University14, University of Milan15, Discovery Institute16, Harvard University17, University of Tokyo18, University of Edinburgh19, Duke University20, University of Texas Southwestern Medical Center21, Karolinska Institutet22, Cambridge University Hospitals NHS Foundation Trust23, Canberra Hospital24, Hyogo College of Medicine25, Wellcome Trust Sanger Institute26, University of California, San Diego27, University of Bonn28, Washington University in St. Louis29, Massachusetts Institute of Technology30
TL;DR: The present work, completely supported by physical clones, provides the most comprehensive survey of a mammalian transcriptome so far, and is a valuable resource for functional genomics.
Abstract: Only a small proportion of the mouse genome is transcribed into mature messenger RNA transcripts There is an international collaborative effort to identify all full-length mRNA transcripts from the mouse, and to ensure that each is represented in a physical collection of clones Here we report the manual annotation of 60,770 full-length mouse complementary DNA sequences These are clustered into 33,409 'transcriptional units', contributing 901% of a newly established mouse transcriptome database Of these transcriptional units, 4,258 are new protein-coding and 11,665 are new non-coding messages, indicating that non-coding RNA is a major component of the transcriptome 41% of all transcriptional units showed evidence of alternative splicing In protein-coding transcripts, 79% of splice variations altered the protein product Whole-transcriptome analyses resulted in the identification of 2,431 sense-antisense pairs The present work, completely supported by physical clones, provides the most comprehensive survey of a mammalian transcriptome so far, and is a valuable resource for functional genomics
1,663 citations
TL;DR: A leptin-dependent neuronal regulation of bone formation with potential therapeutic implications for osteoporosis is demonstrated, and the peripheral mediators of leptin antiosteogenic function appear to be neuronal.
1,550 citations
TL;DR: The primary focus of this lecture will be on the first of these issues, which is the pathophysiological basis for type 2 diabetes and why is their rate of appearance accelerating so rapidly at this particular juncture of human history.
Abstract: Readers of this journal do not need to be reminded of the explosive increase in obesity/type 2 diabetes syndromes and their attendant staggering public health costs that are currently afflicting developed countries. Because of this alarming development and what it portends for the future if left unchecked, the American Diabetes Association, together with its counterparts around the world, as well as the World Health Organization, are faced with the daunting challenge of finding answers to two huge questions. First, what is the pathophysiological basis for these disorders? Second, why is their rate of appearance accelerating so rapidly at this particular juncture of human history, and what, if anything, can we do to intervene? The primary focus of this lecture will be on the first of these issues. I want to emphasize at the outset that I do not plan to dwell exclusively on our own studies in this area. Instead, I shall try to incorporate recent developments from a variety of other laboratories working in the field. Although these will of necessity have to be highly selective, I hope that collectively they will illustrate how we have come to a relatively new and exciting way of thinking about the etiology of type 2 diabetes.
It has been said in literary circles that James Joyce’s Ulysses is probably the most frequently opened and least read book that has ever been published. In a similar vein, I sometimes think that the question of what causes type 2 diabetes might be one of the most frequently asked and least satisfactorily answered in the history of diabetes research. This is not meant to be an arrogant statement, nor indeed does it imply that I have a magical solution to the question at hand. Rather, it simply reflects the fact that at the dawn of …
1,464 citations
TL;DR: Calcium signaling activates the phosphatase calcineurin and induces movement of NFATc proteins into the nucleus, where they cooperate with other proteins to form complexes on DNA.
1,335 citations
TL;DR: The human cytochrome P450 (CYP) superfamily comprises 57 genes that code for enzymes that can have a role in: metabolism of drugs, foreign chemicals, arachidonic acid and eicosanoids; cholesterol metabolism and bile-acid biosynthesis; steroid synthesis and metabolism; vitamin D(3) synthesis; retinoic acid hydroxylation; and those of still unknown function.
1,317 citations
TL;DR: The findings show that HIV-specific CD4+ T cells are preferentially infected by HIV in vivo, which provides a potential mechanism to explain the loss of HIV- specific CD4- T-cell responses, and consequently theloss of immunological control of HIV replication.
Abstract: HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production. A central, yet unresolved issue of HIV disease is the mechanism for this loss, and in particular whether HIV-specific CD4(+) T cells are preferentially affected. Here we show that HIV-specific memory CD4(+) T cells in infected individuals contain more HIV viral DNA than other memory CD4(+) T cells, at all stages of HIV disease. Additionally, following viral rebound during interruption of antiretroviral therapy, the frequency of HIV viral DNA in the HIV-specific pool of memory CD4(+) T cells increases to a greater extent than in memory CD4(+) T cells of other specificities. These findings show that HIV-specific CD4(+) T cells are preferentially infected by HIV in vivo. This provides a potential mechanism to explain the loss of HIV-specific CD4(+) T-cell responses, and consequently the loss of immunological control of HIV replication. Furthermore, the phenomenon of HIV specifically infecting the very cells that respond to it adds a cautionary note to the practice of structured therapy interruption.
1,283 citations
TL;DR: It is shown that a form of protein synthesis-dependent synaptic plasticity, long-term depression triggered by activation of metabotropic glutamate receptors, is selectively enhanced in the hippocampus of mutant mice lacking FMRP.
Abstract: Fragile X syndrome, the most common inherited form of human mental retardation, is caused by mutations of the Fmr1 gene that encodes the fragile X mental retardation protein (FMRP). Biochemical evidence indicates that FMRP binds a subset of mRNAs and acts as a regulator of translation. However, the consequences of FMRP loss on neuronal function in mammals remain unknown. Here we show that a form of protein synthesis-dependent synaptic plasticity, long-term depression triggered by activation of metabotropic glutamate receptors, is selectively enhanced in the hippocampus of mutant mice lacking FMRP. This finding indicates that FMRP plays an important functional role in regulating activity-dependent synaptic plasticity in the brain and suggests new therapeutic approaches for fragile X syndrome.
TL;DR: The interplay between the IFN system and four medically important and challenging viruses — influenza, hepatitis C, herpes simplex and vaccinia — is discussed to highlight the diversity of viral strategies.
Abstract: The action of interferons (IFNs) on virus-infected cells and surrounding tissues elicits an antiviral state that is characterized by the expression and antiviral activity of IFN-stimulated genes. In turn, viruses encode mechanisms to counteract the host response and support efficient viral replication, thereby minimizing the therapeutic antiviral power of IFNs. In this review, we discuss the interplay between the IFN system and four medically important and challenging viruses -- influenza, hepatitis C, herpes simplex and vaccinia -- to highlight the diversity of viral strategies. Understanding the complex network of cellular antiviral processes and virus-host interactions should aid in identifying new and common targets for the therapeutic intervention of virus infection. This effort must take advantage of the recent developments in functional genomics, bioinformatics and other emerging technologies.
TL;DR: This work proposes that the molecular address for proteins targeted to lipid domains is a lipid shell, which is high in cholesterol and sphingolipids, have a light buoyant density, and function in both endocytosis and cell signaling.
Abstract: The surface membrane of cells is studded with morphologically distinct regions, or domains, like microvilli, cell-cell junctions, and coated pits. Each of these domains is specialized for a particular function, such as nutrient absorption, cell-cell communication, and endocytosis. Lipid domains, which include caveolae and rafts, are one of the least understood membrane domains. These domains are high in cholesterol and sphingolipids, have a light buoyant density, and function in both endocytosis and cell signaling. A major mystery, however, is how resident molecules are targeted to lipid domains. Here, we propose that the molecular address for proteins targeted to lipid domains is a lipid shell.
Journal Article•
TL;DR: Three BRAF mutations identified in this study are novel, altering residues important in AKT-mediated BRAF phosphorylation and suggesting that disruption ofAKT-induced BRAF inhibition can play a role in malignant transformation, first report of mutations documenting this interaction in human cancers.
Abstract: BRAF encodes a RAS-regulated kinase that mediates cell growth and malignant transformation kinase pathway activation. Recently, we have identified activating BRAF mutations in 66% of melanomas and a smaller percentage of many other human cancers. To determine whether BRAF mutations account for the MAP kinase pathway activation common in non-small cell lung carcinomas (NSCLCs) and to extend the initial findings in melanoma, we screened DNA from 179 NSCLCs and 35 melanomas for BRAF mutations (exons 11 and 15). We identified BRAF mutations in 5 NSCLCs (3%; one V599 and four non-V599) and 22 melanomas (63%; 21 V599 and 1 non-V599). Three BRAF mutations identified in this study are novel, altering residues important in AKT-mediated BRAF phosphorylation and suggesting that disruption of AKT-induced BRAF inhibition can play a role in malignant transformation. To our knowledge, this is the first report of mutations documenting this interaction in human cancers. Although >90% of BRAF mutations in melanoma involve codon 599 (57 of 60), 8 of 9 BRAF mutations reported to date in NSCLC are non-V599 (89%; P < 10(-7)), strongly suggesting that BRAF mutations in NSCLC are qualitatively different from those in melanoma; thus, there may be therapeutic differences between lung cancer and melanoma in response to RAF inhibitors. Although uncommon, BRAF mutations in human lung cancers may identify a subset of tumors sensitive to targeted therapy.
TL;DR: Activation of VDR by LCA or vitamin D induced expression in vivo of CYP3A, a cytochrome P450 enzyme that detoxifies LCA in the liver and intestine offers a mechanism that may explain the proposed protective effects of vitamin D and its receptor against colon cancer.
Abstract: The vitamin D receptor (VDR) mediates the effects of the calcemic hormone 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3]. We show that VDR also functions as a receptor for the secondary bile acid lithocholic acid (LCA), which is hepatotoxic and a potential enteric carcinogen. VDR is an order of magnitude more sensitive to LCA and its metabolites than are other nuclear receptors. Activation of VDR by LCA or vitamin D induced expression in vivo of CYP3A, a cytochrome P450 enzyme that detoxifies LCA in the liver and intestine. These studies offer a mechanism that may explain the proposed protective effects of vitamin D and its receptor against colon cancer.
TL;DR: HCV-1-infected patients who can be maintained on >80% of their interferon or peginterferon alpha-2b and ribavirin dosage for the duration of treatment in the setting of a clinical trial exhibit enhanced sustained response rates.
National Institutes of Health1, University of Washington2, Centers for Disease Control and Prevention3, University of Massachusetts Medical School4, University of Wisconsin-Madison5, Brown University6, Harvard University7, University of Texas Southwestern Medical Center8, Sharp Memorial Hospital9, Columbia University10, University of Minnesota11, University of North Carolina at Chapel Hill12, Boston Children's Hospital13
TL;DR: The recommended preventive strategies with the strongest supportive evidence are education and training of healthcare providers who insert and maintain catheters, and maximal sterile barrier precautions during central venous catheter insertion, which can reduce the risk for serious catheter-related infection.
Abstract: Background:Although many catheter-related blood-stream infections (CRBSIs) are preventable, measures to reduce these infections are not uniformly implementedObjective:To update an existing evidenced-based guideline that promotes strategies to prevent CRBSIsData Sources:The MEDLINE database, conference proceedings, and bibliographies of review articles and book chapters were searched for relevant articlesStudies Included:Laboratory-based studies, controlled clinical trials, prospective interventional trials, and epidemiologic investigationsOutcome Measures:Reduction in CRBSI, catheter colonization, or catheter-related infectionSynthesis:The recommended preventive strategies with the strongest supportive evidence are education and training of healthcare providers who insert and maintain catheters; maximal sterile barrier precautions during central venous catheter insertion; use of a 2% chlorhexidine preparation for skin antisepsis; no routine replacement of central venous catheters for prevention of infection; and use of antiseptic/antibiotic-impregnated short-term central venous catheters if the rate of infection is high despite adherence to other strategies (ie, education and training, maximal sterile barrier precautions, and 2% chlorhexidine for skin antisepsis)Conclusion:Successful implementation of these evidence-based interventions can reduce the risk for serious catheter-related infection
TL;DR: By facilitating sterol-dependent ER retention of SCAP, INSIG-1 plays a central role in cholesterol homeostasis.
TL;DR: It is shown that class II HDACs are substrates for a stress-responsive kinase specific for conserved serines that regulate MEF2-HDAC interactions, and act as signal-responsive suppressors of the transcriptional program governing cardiac hypertrophy and heart failure.
TL;DR: Molecular modeling was used to identify the caspase recruitment and WD40 domains within the apoptosome and to infer likely positions of the CED4 homology motif and cytochrome c, suggesting a plausible role for cy tochrome c in apoptosomes assembly.
TL;DR: The currently known components of the telomerase complex are described and an update is provided on the molecular mechanisms of human telomere regulation to provide an update in antiaging and anticancer therapy.
Abstract: The telomere is a special functional complex at the end of linear eukaryotic chromosomes, consisting of tandem repeat DNA sequences and associated proteins. It is essential for maintaining the integrity and stability of linear eukaryotic genomes. Telomere length regulation and maintenance contribute to normal human cellular aging and human diseases. The synthesis of telomeres is mainly achieved by the cellular reverse transcriptase telomerase, an RNA-dependent DNA polymerase that adds telomeric DNA to telomeres. Expression of telomerase is usually required for cell immortalization and long-term tumor growth. In humans, telomerase activity is tightly regulated during development and oncogenesis. The modulation of telomerase activity may therefore have important implications in antiaging and anticancer therapy. This review describes the currently known components of the telomerase complex and attempts to provide an update on the molecular mechanisms of human telomerase regulation.
TL;DR: The addition of ABCG5 and ABCG8 to the growing list of LXR target genes further supports the notion that LXRs serve as sterol sensors to coordinately regulate sterol catabolism, storage, efflux, and elimination.
TL;DR: Glutamatergic synaptic transmission was reconstituted in nonneuronal cells by coexpressing glutamate receptors with SynCAM, which suggests that a single type of adhesion molecule and glutamate receptor are sufficient for a functional postsynaptic response.
Abstract: Synapses, the junctions between nerve cells through which they communicate, are formed by the coordinated assembly and tight attachment of pre- and postsynaptic specializations. We now show that SynCAM is a brain-specific, immunoglobulin domain-containing protein that binds to intracellular PDZ-domain proteins and functions as a homophilic cell adhesion molecule at the synapse. Expression of the isolated cytoplasmic tail of SynCAM in neurons inhibited synapse assembly. Conversely, expression of full-length SynCAM in nonneuronal cells induced synapse formation by cocultured hippocampal neurons with normal release properties. Glutamatergic synaptic transmission was reconstituted in these nonneuronal cells by coexpressing glutamate receptors with SynCAM, which suggests that a single type of adhesion molecule and glutamate receptor are sufficient for a functional postsynaptic response.
TL;DR: The crystal structure of a stable dimer formed by the E171Q mutant of the MJ0796 ABC, which is hydrolytically inactive due to mutation of the catalytic base, is reported, establishing the stereochemical basis of the power stroke of ABC transporter pumps.
TL;DR: Patients with limbs at high risk for amputation can be advised that reconstruction typically results in two-year outcomes equivalent to those of amputation.
Abstract: Background Limb salvage for severe trauma has replaced amputation as the primary treatment in many trauma centers. However, long-term outcomes after limb reconstruction or amputation have not been fully evaluated. Methods We performed a multicenter, prospective, observational study to determine the functional outcomes of 569 patients with severe leg injuries resulting in reconstruction or amputation. The principal outcome measure was the Sickness Impact Profile, a multidimensional measure of self-reported health status (scores range from 0 to 100; scores for the general population average 2 to 3, and scores greater than 10 represent severe disability). Secondary outcomes included limb status and the presence or absence of major complications resulting in rehospitalization. Results At two years, there was no significant difference in scores for the Sickness Impact Profile between the amputation and reconstruction groups (12.6 vs. 11.8, P=0.53). After adjustment for the characteristics of the patients and t...
TL;DR: It is indicated that ABCG5 and ABCG8 are required for efficient secretion of cholesterol into bile and that disruption of these genes increases dramatically the responsiveness of plasma and hepatic cholesterol levels to changes in dietary cholesterol content.
Abstract: Cholesterol and other sterols exit the body primarily by secretion into bile. In patients with sitosterolemia, mutations in either of two ATP-binding cassette (ABC) half-transporters, ABCG5 or ABCG8, lead to reduced secretion of sterols into bile, implicating these transporters in this process. To elucidate the roles of ABCG5 and ABCG8 in the trafficking of sterols, we disrupted Abcg5 and Abcg8 in mice (G5G8−/−). The G5G8−/− mice had a 2- to 3-fold increase in the fractional absorption of dietary plant sterols, which was associated with an ≈30-fold increase in plasma sitosterol. Biliary cholesterol concentrations were extremely low in the G5G8−/− mice when compared with wild-type animals (mean = 0.4 vs. 5.5 μmol/ml) and increased only modestly with cholesterol feeding. Plasma and liver cholesterol levels were reduced by 50% in the chow-fed G5G8−/− mice and increased 2.4- and 18-fold, respectively, after cholesterol feeding. These data indicate that ABCG5 and ABCG8 are required for efficient secretion of cholesterol into bile and that disruption of these genes increases dramatically the responsiveness of plasma and hepatic cholesterol levels to changes in dietary cholesterol content.
TL;DR: It is demonstrated that increased expression of ABCG5 and ABCG8 selectively drives biliaryneutral sterol secretion and reduces intestinal cholesterol absorption, leading to a selective increase in neutral sterol excretion and a compensatory increase in cholesterol synthesis.
Abstract: Two ATP-binding cassette (ABC) transporters, ABCG5 and ABCG8, have been proposed to limit sterol absorption and to promote biliary sterol excretion in humans. To test this hypothesis, a P1 clone containing the human ABCG5 and ABCG8 genes was used to generate transgenic mice. The transgenes were expressed primarily in the liver and small intestine, mirroring the expression pattern of the endogenous genes. Transgene expression only modestly affected plasma and liver cholesterol levels but profoundly altered cholesterol transport. The fractional absorption of dietary cholesterol was reduced by about 50%, and biliary cholesterol levels were increased more than fivefold. Fecal neutral sterol excretion was increased three- to sixfold and hepatic cholesterol synthesis increased two- to fourfold in the transgenic mice. No significant changes in the pool size, composition, and fecal excretion of bile acids were observed in the transgenic mice. Transgene expression attenuated the increase in hepatic cholesterol content induced by consumption of a high cholesterol diet. These results demonstrate that increased expression of ABCG5 and ABCG8 selectively drives biliary neutral sterol secretion and reduces intestinal cholesterol absorption, leading to a selective increase in neutral sterol excretion and a compensatory increase in cholesterol synthesis.
TL;DR: The post-translational mechanisms that confer calcium-sensitivity to MEF2 and its downstream target genes are described, and how this transcription factor can control diverse and mutually exclusive cellular decisions is considered.
TL;DR: Dutasteride is a potent inhibitor of dihydrotestosterone production that is safe and effective in terms of the reduction of prostate volume and symptoms, flow rate improvement, and the reduction the risk of acute urinary retention and surgery during a 24-month study period.
TL;DR: Transgenic mice that selectively express in skeletal muscle a constitutively active form of calcium/calmodulin–dependent protein kinase IV showed augmented mitochondrial DNA replication and mitochondrial biogenesis, up-regulation of mitochondrial enzymes involved in fatty acid metabolism and electron transport, and reduced susceptibility to fatigue during repetitive contractions.
Abstract: Endurance exercise training promotes mitochondrial biogenesis in skeletal muscle and enhances muscle oxidative capacity, but the signaling mechanisms involved are poorly understood. To investigate this adaptive process, we generated transgenic mice that selectively express in skeletal muscle a constitutively active form of calcium/calmodulin-dependent protein kinase IV (CaMKIV*). Skeletal muscles from these mice showed augmented mitochondrial DNA replication and mitochondrial biogenesis, up-regulation of mitochondrial enzymes involved in fatty acid metabolism and electron transport, and reduced susceptibility to fatigue during repetitive contractions. CaMK induced expression of peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1), a master regulator of mitochondrial biogenesis in vivo, and activated the PGC-1 gene promoter in cultured myocytes. Thus, a calcium-regulated signaling pathway controls mitochondrial biogenesis in mammalian cells.