Cardiac arrests outside hospital.
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Awareness↗
Biomedical subjects
T Evans
Publications and source records attributed to T Evans.
Effects of dietary vitamin E supplementation during late pregnancy on lamb mortality and ewe productivity.
OBJECTIVE: To determine the effect of feeding vitamin E to ewes during late pregnancy on lamb mortality and ewe productivity. DESIGN: Prospective study. ANIMALS: 1,302 mature Rambouillet and Targhee ewes. PROCEDURE: During a 3-year period, approximately 430 ewes/y were randomly allocated to 2 groups; supplement-group ewes were fed additional vitamin E and control-group ewes were not. Beginning approximately 3 weeks before the first expected lambing date, ewes were fed 2.3 kg (5 lb) of alfalfa-grass hay/d and 0.23 kg (0.5 lb) of barley-based pellets/d with or without supplemental vitamin E. Pellets that were supplemented contained 1,450 mg of DL-alpha-tocopherol acetate/kg (658 mg/lb) of feed and provided an additional 330 IU of vitamin E/ewe/d. Selenium was incorporated into a trace mineral salt and fed free choice to all ewes throughout pregnancy. RESULTS: Supplemental vitamin E had no effect on ewe weight, body condition score, fertility, or prolificacy. In ewes that lambed in the early part of the lambing season, vitamin E supplementation significantly reduced lamb mortality, compared with no supplementation (12 vs 17%, respectively). Consequently, supplement-group ewes had significantly greater total body weight of lambs per ewe at the time of weaning, compared with control-group ewes. Differences were not observed between ewe groups in lamb mortality or total body weight of lambs per ewe at the time of weaning when ewes lambed during the late part of the lambing season. CLINICAL IMPLICATIONS: If ewes are fed additional vitamin E3 weeks before parturition, those that lamb in the early part of the lambing season may have low lamb mortality and, thus, higher total body weight of lambs per ewe at the time of weaning.
Animals↗
No evidence for the H133Y mutation in SONIC HEDGEHOG in a collection of common tumour types.
The human homologue of the Drosophila segment polarity gene patched is mutated in the cancer predisposition syndrome naevoid basal cell carcinoma syndrome (NBCCS), as well as in several types of tumour associated with the disorder. It was recently reported that a single recurrent mutation in the SONIC HEDGEHOG gene, which encodes the PATCHED ligand, was found in one of 43 basal cell carcinomas (BCCs), one of 14 medulloblastomas and one of six breast carcinomas analysed (Oro et al., 1997). We have searched extensively for this same mutation in a large collection of BCCs, medulloblastomas and carcinomas of the breast, ovary and colorectum and have failed to detect the mutation in any sample analysed.
Adolescent↗
Distinct functions are implicated for the GATA-4, -5, and -6 transcription factors in the regulation of intestine epithelial cell differentiation.
Based on conserved expression patterns, three members of the GATA family of transcriptional regulatory proteins, GATA-4, -5, and -6, are thought to be involved in the regulation of cardiogenesis and gut development. Functions for these factors are known in the heart, but relatively little is understood regarding their possible roles in the regulation of gut-specific gene expression. In this study, we analyze the expression and function of GATA-4, -5, and -6 using three separate but complementary vertebrate systems, and the results support a function for these proteins in regulating the terminal-differentiation program of intestinal epithelial cells. We show that xGATA-4, -5, and -6 can stimulate directly activity of the promoter for the intestinal fatty acid-binding protein (xIFABP) gene, which is a marker for differentiated enterocytes. This is the first direct demonstration of a target for GATA factors in the vertebrate intestinal epithelium. Transactivation by xGATA-4, -5, and -6 is mediated at least in part by a defined proximal IFABP promoter element. The expression patterns for cGATA-4, -5, and -6 are markedly distinct along the proximal-distal villus axis. Transcript levels for cGATA-4 increase along the axis toward the villus tip; likewise, cGATA-5 transcripts are largely restricted to the distal tip containing differentiated cells. In contrast, the pattern of cGATA-6 transcripts is complementary to cGATA-5, with highest levels detected in the region of proliferating progenitor cells. Undifferentiated and proliferating human HT-29 cells express hGATA-6 but not hGATA-4 or hGATA-5. Upon stimulation to differentiate, the transcript levels for hGATA-5 increase, and this occurs prior to increased transcription of the terminal differentiation marker intestinal alkaline phosphatase. At the same time, hGATA-6 steady-state transcript levels decline appreciably. All of the data are consistent with evolutionarily conserved but distinct roles for these factors in regulating the differentiation program of intestinal epithelium. Based on this data, we suggest that GATA-6 might function primarily within the proliferating progenitor population, while GATA-4 and GATA-5 function during differentiation to activate terminal-differentiation genes including IFABP.
Animals↗
Binding of the transcription factor interferon regulatory factor-1 to the inducible nitric-oxide synthase promoter.
Nitric oxide production in a variety of inflammatory conditions is dependent on the synthesis of the enzyme, inducible nitric-oxide synthase (iNOS). The gene for this enzyme is regulated by a number of inflammatory cytokines, including interferon-gamma. Transcriptional activation of the gene is dependent on the interferon-gamma-induced transcription factor, interferon regulatory factor-1 (IRF-1). Using a 99-base pair segment of the iNOS gene promoter encompassing nucleotides -979 to -881, a region essential for gene activation by cytokines, we show that with increasing concentrations of added IRF-1, a monomeric then a dimeric complex form. Molecular footprinting analysis shows that the factor binds initially to a canonical IRF-1 site as a monomer. The region of binding is then extended both in a 5' and 3' direction on formation of the dimeric complex, with additional contacts in the minor groove of DNA. Binding of the second molecule of IRF-1 is dependent on the presence of the initial bound protein. Sequential binding of IRF-1 to form a dimeric complex has not been described previously, and we show that formation of this dimeric complex is essential for full activation of the iNOS gene by cytokines in vascular smooth muscle cells.
Animals↗
Developmental biology of hematopoiesis.
Hematopoietic stem cells are at the top of a hierarchy that regulates the generation of a vast repertoire of blood cells during the lifetime of a vertebrate. Recent experiments, using a vast variety of embryonic systems, shed new light on the origin of stem cells and the genes that function to regulate and maintain hematopoietic differentiation programs. Two distinct populations of stem cells develop--derived initially from transient, extraembryonic source and later from a stable, intraembryonic source; it is possible that both are generated from a pro-HSC able to respond differentially to local inductions. The initial blood cells develop from ventral mesoderm. The blood-forming region develops as a result of signaling from specific, secreted, embryonic growth factors, including the bone morphogenetic proteins. Stem cells give rise to progenitors that are restricted progressively in their ability to contribute to specific lineages. This process is regulated by transcription factors, whose functions are confirmed through genetic analyses. The identification of highly conserved, embryonic signaling pathways and transcription regulatory genes illustrates the enormous utility of analyzing embryonic hematopoiesis in frog, chick, fish, and mouse systems to further our understanding of human stem cells.
Animals↗
Differential regulation of neurogenesis by the two Xenopus GATA-1 genes.
Previously, we have shown that the ventralizing factor bone morphogenetic protein 4 (BMP-4) can inhibit Xenopus neurogenesis. The erythroid transcription factor GATA-1 functions downstream of the BMP-4 signaling pathway and mediates BMP-4-induced erythropoiesis. We have found that similar to BMP-4, GATA-1b inhibits neuralization of Xenopus animal cap (AC) cells. The neural inhibition is not seen with GATA-1a, although both GATA-1a and GATA-1b RNAs are translated at the same efficiency and induce globin expression equally in AC cells. GATA-1b RNA injection into AC cells neither induces expression of Xbra (a general mesoderm marker) nor affects expression of XK81 (epidermal keratin) or BMP-4 and Xvent-1 (two ventral markers). These data suggest that GATA-1b retains the epidermal fate of the AC. Intact GATA-1b protein is required for both inhibition of neurogenesis and induction of globin expression. Our findings indicate that GATA-1b can function in ectoderm to specifically regulate neural inducing mechanisms, apparently related to the expression of chordin, a neuralizing gene. Furthermore, tadpole stage embryos injected with GATA-1b are devoid of all dorsoanterior structures including neural tissue. This report provides evidence that the two transcription factors, derived from a recent genome duplication, share a common biological activity (stimulation of erythropoiesis) while also exhibiting a distinct function (inhibition of neurogenesis).
Animals↗
The human GATA-6 gene: structure, chromosomal location, and regulation of expression by tissue-specific and mitogen-responsive signals.
GATA factors constitute a family of transcriptional regulatory proteins expressed with distinct developmental and tissue-specific profiles and thought to regulate cell-restricted programs of gene expression. Here we describe the molecular cloning, chromosomal location, and transcription of the human GATA-6 gene. The GATA-6 cDNA encodes a predicted 449-amino-acid protein, which is highly conserved among vertebrates, and includes the two adjacent zinc-finger/basic domains characteristic of the GATA factor family. GATA-6 maps to human chromosome 18q11.1-q11.2 by fluorescence in situ hybridization. The gene is transcribed in a pattern overlapping that of GATA-4. Transcripts for both of these genes are prominent in heart, pancreas, and ovary, but only GATA-6 mRNA is found in lung and liver. GATA-6 transcripts are also detected in cultures of human and rat vascular smooth muscle cells (VSMCs). In VSMCs, GATA-6 transcripts are down- regulated when quiescent cultures are stimulated to proliferate in response to mitogen activation. These data demonstrate that GATA-6 is subject to both tissue-specific and mitogen-responsive regulatory signals. GATA-6 is a prime candidate for a gene that might regulate the differentiative state of VSMCs.
Amino Acid Sequence↗
Mammalian Cdc42 is a brefeldin A-sensitive component of the Golgi apparatus.
In this study, we have used immunocytochemical and fractionation approaches to provide a description of the localization of the mammalian Cdc42 protein (designated Cdc42Hs) in vivo. A specific anti-peptide antibody was generated against the C-terminal region of Cdc42Hs. Using affinity-purified preparations of this antibody in indirect immunofluorescence experiments, Cdc42Hs was found to be localized to the Golgi apparatus. Similar to the well-characterized non-clathrin coat proteins ADP-ribosylation factor (ARF) and beta-COP, the perinuclear clustering of Cdc42Hs is rapidly dispersed upon exposure of the cells to the drug brefeldin A, suggesting that it too may play a role in the processes of intracellular lipid and protein transport. Employing cell lines possessing inducible forms of ARF, we demonstrate here a tight coupling of the nucleotide-bound state of ARF and the subcellular localization of Cdc42Hs. Specifically, the expression of wild-type ARF had no effect on the brefeldin A sensitivity of Cdc42Hs while, as is the case for ARF and beta-COP, expression of a GTPase-deficient form of ARF (ARF(Q71L)) renders these Golgi-localized proteins resistant to brefeldin A treatment (; ). Moreover, the induced expression of a mutant form of ARF with a low affinity for nucleotide resulted in constitutive redistribution of Cdc42Hs in the absence of brefeldin A treatment. These results suggest that Cdc42Hs may play a role in cell morphogenesis by acting on targets in the Golgi that direct polarized growth at the plasma membrane.
Animals↗
The Xenopus GATA-4/5/6 genes are associated with cardiac specification and can regulate cardiac-specific transcription during embryogenesis.
The GATA family of nuclear factors has been implicated in the regulation of cell type-specific transcription. We report the isolation of the Xenopus GATA-4 and GATA-6 cDNA clones and characterize the expression patterns of the xGATA-4/5/6 genes. By comparing the sequence of the cDNAs with those previously reported from chick and mammalian sources, we conclude that each is conserved across vertebrate evolution as a distinct gene product. Each gene is expressed in differentiated adult heart and gut, but maintains distinct transcript patterns in various other adult tissues. During embryogenesis, each gene displays a similar overlapping distribution of transcripts localized throughout the developing cardiogenic region. The xGATA-4 gene can be detected in dorsal cardiac progenitor rudiments prior to migration. Axis disruption experiments were used to demonstrate that transcription of these genes is intimately associated with the specification of cardiac progenitors. Ectopic expression of each gene is specifically capable of activating during embryogenesis the transcription of the cardiac genes encoding actin and myosin heavy chain alpha. The data are consistent with a primary role for the GATA-4/5/6 genes in regulating heart development.
Amino Acid Sequence↗
BMP-like signals are required after the midblastula transition for blood cell development.
We have investigated the process by which the primitive erythroid cells develop during early vertebrate embryogenesis. Cultured Xenopus animal cap (AC) cells transiently activate the transcription of blood cell regulatory genes GATA-1 and GATA-2 but fail to commit stably to the blood lineage. By contrast, cells of the presumptive ventral marginal zone (VMZ), are committed by the midblastula transition (MBT) to express fully on erythroid program. Growth factor BMP-4, a member of the TGF-beta family of signaling molecules, has been implicated in the process of ventral mesoderm patterning. We show that expression of BMP-4 after MBT is sufficient to induce the blood program fully in AC cells. This includes high level expression of the blood markers SCL and globin, which are not activated in AC cells from uninjected embryos. Likewise, expression of a dominant negative receptor after MBT results in relatively normal embryos, which, however, completely lack differentiated blood cells. Our results are consistent with a role for BMP or BMP-like signaling during gastrulation in the differentiation of embryonic blood.
Animals↗
SSI1 encodes a novel Hsp70 of the Saccharomyces cerevisiae endoplasmic reticulum.
The endoplasmic reticulum (ER) of the budding yeast Saccharomyces cerevisiae contains a well-characterized, essential member of the Hsp70 family of molecular chaperones, Kar2p. Kar2p has been shown to be involved in the translocation of proteins into the ER as well as the proper folding of proteins in that compartment. We report the characterization of a novel Hsp70 of the ER, Ssi1p. Ssi1p, which shares 24% of the amino acids of Kar2p, is not essential for growth under normal conditions. However, deletion of SSI1 results in cold sensitivity as well as enhanced resistance to manganese. The localization of Ssi1p to the ER, suggested by the presence of a conserved S. cerevisiae ER retention signal at its C terminus, was confirmed by subcellular fractionation, protease protection assays, and immunofluorescence. The SSI1 promoter contains an element with similarity to the unfolded protein response element of KAR2. Like KAR2, SSI1 is induced both in the presence of tunicamycin and in a kar2-159 mutant strain, conditions which lead to an accumulation of unfolded proteins in the ER. Unlike KAR2, however, SSI1 is not induced by heat shock. Deletion of SSI1 shows a complex pattern of genetic interactions with various conditional alleles of KAR2, ranging from synthetic lethality to synthetic rescue. Interestingly, SSI1 deletion strains show a partial block in translocation of multiple proteins into the ER, suggesting that Ssi1p plays a direct role in the translocation process.
Amino Acid Sequence↗
DHEAS as an effective vaccine adjuvant in elderly humans. Proof-of-principle studies.
We have demonstrated that in aged mice, the titer of serum antibody induced against tetanus toxoid correlates with resistance to local paralysis caused by injection of tetanus toxin. Only mice immunized shortly after oral dosing with DHEAS demonstrated high serum antibody titers and complete protection from paralysis. These results became the basis for initiating proof-of-principle studies in human volunteers above age 65 using a licensed influenza vaccine and tetanus toxoid in two independent studies. The use of an oral delivery form of DHEAS before influenza vaccination was associated with a demonstrable increase in the number of individuals with a fourfold increase in HAI titers following vaccination. The overall mean increase in HAI titers was highest in the DHEAS-treated group. The use of DHEAS in the immunization of elderly subjects against tetanus toxoid, while unable to enhance the responses, was not a detriment to antibody response. We conclude that further studies will justify the use of DHEAS as an adjuvant for antigens that represent primary responses in the elderly.
Adjuvants, Immunologic↗
Assessing health needs in primary care. Tailor data collection to needs.
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Data Collection↗
PDGF stimulates an increase in GTP-Rac via activation of phosphoinositide 3-kinase.
BACKGROUND: Phosphoinositide 3-kinases (PI 3-kinases) are thought to play an important role in coordinating the responses elicited by a variety of growth factors, oncogene products and inflammatory stimuli. These responses include activation of membrane ruffling, chemotaxis, glucose transport, superoxide production, neurite outgrowth and pp70 S6 kinase. Some of these responses are also known to be regulated by Rac, a small GTP-binding protein related to Ras. Neither the transducing elements upstream of Rac, nor those downstream of PI 3-kinase, have been defined. RESULTS: We show here that platelet-derived growth factor (PDGF) can stimulate an increase in the level of GTP-Rac by at least two distinct mechanisms: firstly, by increased guanine nucleotide exchange; and secondly, by inhibition of a Rac GTPase activity. The first of these mechanisms is essential for the activation of Rac, and we show that it is dependent upon PDGR-stimulated synthesis of phosphatidylinositol (3,4,5)-trisphosphate. CONCLUSIONS: These results suggest that Rac activation lies downstream of PI 3-kinase activation on a PDGF-stimulated signalling pathway. Furthermore, as Rac has been implicated in at least two diverse cellular responses that are also though to require activation of PI 3-kinase--a reorganization of the actin cytoskeleton known as membrane ruffling and the neutrophil oxidative burst--these results suggest that Rac may be a major effector protein for the PI 3-kinase signalling pathway in many cell types.
Cell Line↗
Purification of baculovirus-expressed recombinant Ras and Rap proteins.
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Amino Acid Sequence↗
The Sry-related gene Sox9 is expressed during chondrogenesis in mouse embryos.
Mutations in the human SRY-related gene, SOX9, located on chromosome 17, have recently been associated with the sex reversal and skeletal dysmorphology syndrome, campomelic dysplasia. In order to clarify the role of this gene in skeletal development, we have studied the expression of mouse Sox9 during embryogenesis. Sox9 is expressed predominantly in mesenchymal condensations throughout the embryo before and during the deposition of cartilage, consistent with a primary role in skeletal formation. Interspecific backcross mapping has localized mouse Sox9 to distal chromosome 11. The expression pattern and chromosomal location of Sox9 suggest that it may be the gene defective in the mouse skeletal mutant Tail-short, a potential animal model for campomelic dysplasia.
Amino Acid Sequence↗
Homotypic interactions of chicken GATA-1 can mediate transcriptional activation.
We used a one-hybrid system to replace precisely the finger II chicken GATA-1 DNA-binding domain with the binding domain of bacterial repressor protein LexA. The LexA DNA-binding domain lacks amino acids that function for transcriptional activation, nuclear localization, or protein dimerization. This allowed us to analyze activities of GATA-1 sequences distinct from DNA binding. We found that strong transcriptional activating sequences that function independently of finger II are present in GATA-1. Sequences including finger I contain an independent nuclear localizing function. Our data are consistent with cooperative binding of two LexA-GATA-1 hybrid proteins on a palindromic operator. The sensitivity of our transcription assay provides the first evidence that GATA-1 can make homotypic interactions in vivo. The ability of a non-DNA-binding form of GATA-1 to activate gene expression by targeting to a bound GATA-1 derivative further supports the notion that GATA-1-GATA-1 interactions may have functional consequences. A coimmunoprecipitation assay was used to demonstrate that GATA-1 multimeric complexes form in solution by protein-protein interaction. The novel ability of GATA-1 to interact homotypically may be important for the formation of higher-order structures among distant regulatory elements that share binding sites for this transcription factor. We also used the system to test the ability of GATA-1 to interact heterotypically with other activators.
Amino Acid Sequence↗