Biomedical subjects

Patrick G Gallagher

Publications and source records attributed to Patrick G Gallagher.

24 records · Page 2Linked to original sources

PubMed2004

Conjunctival colonization of infants hospitalized in a neonatal intensive care unit: a longitudinal analysis.

OBJECTIVES: To determine the frequency of conjunctival colonization, identify the colonizing flora, and correlate culture results with physical findings in infants in a NICU. DESIGN: Surveillance study. SETTING: Level III NICU of a large university teaching hospital. PATIENTS: All infants admitted for longer than 24 hours during a 26-week period. METHODS: Weekly bacterial conjunctival cultures were performed for all infants. The conjunctival appearance at the time of culture was recorded. The frequency, identity, and correlation of culture results with physical findings were determined. RESULTS: One thousand ninety-one cultures were performed for 319 infants: 133 (42%) had no positive cultures and 186 (58%) had at least one positive culture. Culture analysis revealed that 411 (38%) were positive and yielded 494 isolates comprising more than 18 bacterial species. Bacteria most commonly isolated included coagulase-negative Staphylococcus (CoNS) (75%), viridans group streptococci (8.7%), Staphylococcus aureus (3.8%), Enterococcus species (2.6%), and Serratia marcescens (2.4%). The frequency of non-CoNS isolates increased significantly during the first 6 weeks of patient hospital stay (6% [1 to 3 weeks] to 12% [4 to 6 weeks]; P = .01), with an increasing trend to 15 weeks (18%). Correlation of bacteriologic results with physical findings demonstrated that infants with non-CoNS isolates exhibited conjunctival edema, erythema, or exudates more frequently than did infants with CoNS alone (30% vs 13%; P = .0001). CONCLUSIONS: Conjunctival colonization was common among infants in a NICU. Prolonged hospitalization predisposes to colonization with potentially pathogenic organisms. Physical findings were more likely in patients with non-CoNS conjunctival isolates.

Conjunctival Diseases↗

PubMed2004

Update on the clinical spectrum and genetics of red blood cell membrane disorders.

Disorders of the red blood cell membrane, such as hereditary spherocytosis, hereditary elliptocytosis, and hereditary pyropoikilocytosis, are characterized by heterogeneity in their clinical and laboratory manifestations. Advances in molecular biology have allowed determination of the precise genetic defect in many cases of membrane-associated anemia and have revealed significant genetic heterogeneity. Six genetic loci have been identified and many defects, including gene deletions and insertions, missense and nonsense mutations, and splicing mutations, have been found. Analysis of these defects has provided a better understanding of the pathogenesis of these disorders and allowed a better understanding of the structure/function relationships of the proteins of the erythrocyte membrane.

Anemia, Hemolytic, Congenital↗

PubMed2003

Altered erythrocyte endothelial adherence and membrane phospholipid asymmetry in hereditary hydrocytosis.

The risk for thrombosis is increased in patients with hereditary hydrocytosis, an uncommon variant of hereditary stomatocytosis. Erythrocytes from 2 patients with hydrocytosis were studied to gain insight into the mechanism of thrombosis in this disorder. Erythrocytes demonstrated abnormal osmotic scan ektacytometry and decreased erythrocyte filtration rates. There was also a mild increase in adherence of erythrocytes to endothelial monolayers in a micropipette assay. Adhesion of erythrocytes to the subendothelial matrix proteins thrombospondin and laminin, however, was not significantly increased. Percentages of hydrocytosis erythrocytes and reticulocytes with phosphatidylserine exposed on the outer surfaces were increased in both patients compared with healthy controls, indicating altered membrane phospholipid asymmetry. Increased phosphatidylserine exposure accelerating thrombin-forming processes has been proposed as a mechanism for thrombosis in sickle cell disease and beta-thalassemia and may play a similar role in hereditary hydrocytosis.

Adult↗

PubMed2003

Regulation of erythrocyte membrane protein gene expression.

Proteins of the erythrocyte membrane have served as the prototypes of homologous families of multifunctional proteins in erythroid and nonerythroid cells. These proteins demonstrate many different cell type, tissue-specific, and developmental stage-specific functions. This complex pattern of functional diversity appears to have evolved from the cell type, tissue-specific, developmentally regulated expression of multiple protein isoforms. Isoform diversity arises from different gene products from related genes; from differential, alternate splicing of the same gene product; from the use of tissue-specific promoters; and from alternate polyadenylation. The identification and characterization of the regulatory elements that control erythrocyte membrane protein gene expression have important implications for several biologic processes. These include disease pathogenesis, membrane assembly, hematopoiesis, gene regulation, and direction of other erythroid-specific genes in transgenic mouse and gene therapy applications.

Erythrocyte Membrane↗

PubMed2003

Variegated expression from the murine band 3 (AE1) promoter in transgenic mice is associated with mRNA transcript initiation at upstream start sites and can be suppressed by the addition of the chicken beta-globin 5' HS4 insulator element.

The anion exchanger protein 1 (AE1; band 3) is an abundant erythrocyte transmembrane protein that regulates chloride-bicarbonate exchange and provides an attachment site for the erythrocyte membrane skeleton on the cytoplasmic domain. We analyzed the function of the erythroid AE1 gene promoter by using run-on transcription, RNase protection, transient transfection, and transgenic mouse assays. AE1 mRNA was transcribed at a higher level and maintained at a higher steady-state level than either ankyrin or beta-spectrin in mouse fetal liver cells. When linked to a human gamma-globin gene, two different AE1 promoters directed erythroid-specific expression of gamma-globin mRNA in 18 of 18 lines of transgenic mice. However, variegated expression of gamma-globin was observed in 14 of 18 lines. While there was a significant correlation between transgene copy number and the amount of gamma-globin mRNA in all 18 lines, the transgene mRNAs initiated upstream of the start site of the endogenous AE1 mRNA. Addition of the insulator element from 5'HS4 of the chicken beta-globin cluster to the AE1/gamma-globin transgene allowed position-independent, copy-number-dependent expression at levels similar to the AE1 transcription rate in six of six lines of transgenic mice. The mRNA from the insulated AE1/gamma-globin transgene mapped to the start site of the endogenous AE1 mRNA, and gamma-globin protein was expressed in 100% of erythrocytes in all lines. We conclude that the chicken beta-globin 5'HS4 element is necessary for full function of the AE1 promoter and that position effect variegation is associated with RNA transcription from the upstream start sites.

Animals↗

PubMed2002

Erythroid expression of the human alpha-spectrin gene promoter is mediated by GATA-1- and NF-E2-binding proteins.

alpha-Spectrin is a highly expressed membrane protein critical for the flexibility and stability of the erythrocyte. Qualitative and quantitative defects of alpha-spectrin are present in the erythrocytes of many patients with abnormalities of red blood cell shape including hereditary spherocytosis and elliptocytosis. We wished to determine the regulatory elements that determine the erythroid-specific expression of the alpha-spectrin gene. We mapped the 5' end of the alpha-spectrin erythroid cDNA and cloned the 5' flanking genomic DNA containing the putative alpha-spectrin gene promoter. Using transfection of promoter/reporter plasmids in human tissue culture cell lines, in vitro DNase I footprinting analyses, and gel mobility shift assays, an alpha-spectrin gene erythroid promoter with binding sites for GATA-1- and NF-E2-related proteins was identified. Both binding sites were required for full promoter activity. In transgenic mice, a reporter gene directed by the alpha-spectrin promoter was expressed in yolk sac, fetal liver, and erythroid cells of bone marrow but not adult reticulocytes. No expression of the reporter gene was detected in nonerythroid tissues. We conclude that this alpha-spectrin gene promoter contains the sequences necessary for low level expression in erythroid progenitor cells.

5' Flanking Region↗