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Biomedical subjects

E A Wood

Publications and source records attributed to E A Wood.

11 recordsLinked to original sources
PubMed1997

Relations of Doppler stroke volume and its components to left ventricular stroke volume in normotensive and hypertensive American Indians: the Strong Heart Study.

Doppler echocardiographic measurement of time-velocity integral of blood flow across the aortic annulus ("stroke distance") or of stroke volume (SV) have been proposed as noninvasive measures of cardiac pump performance that could elucidate the hemodynamics of hypertension. To evaluate the performance of these measures of hemodynamic volume load in a population with a wide range of body build and other characteristics, we obtained technically adequate imaging and Doppler echocardiograms in 1,935 of 2,212 (87%) American Indian Strong Heart Study participants, without mitral regurgitation or segmental left ventricular (LV) dysfunction, in Arizona, Oklahoma, and South/North Dakota. The subjects ranged widely in age (48 to 81 years) and body mass index (17.0 to 62.6 kg/m2); 65% were women; 1,161 were normotensive and 774 were hypertensive. As a reference standard, LV and stroke volumes were calculated from LV internal dimensions by the Teichholz method. Doppler SVs were moderately related to LV SVs (r = 0.63), but Doppler SV was slightly lower in both normotensive (mean = 69.8 and 72.9 mL, respectively) and hypertensive subjects (71.1 v 73.6 mL). Aortic stroke distance was less closely related than was aortic annular area to LV SV (r = 0.34 v 0.40, P < .001). Aortic annular area (r = 0.44) but not stroke distance (r = 0.04) was moderately correlated with body surface area. Stroke distance was inversely related to annular area (r = -0.29) and in subjects stratified by aortic annular diameter 1.6 to 1.9, 2.0 to 2.1, and 2.3 to 2.9 cm, mean LV SV increased from 67 to 74 to 80 mL, but average stroke distance fell from 22.8 to 21.6 to 20.1 cm. Stroke distance also failed to identify gender differences in LV SV but did identify that due to obesity. Thus Doppler SV closely parallels independently measured LV SV but slightly underestimates SV in both normotensive and hypertensive adults, whereas aortic stroke distance yields misleading comparisons between genders or individuals of different body sizes.

Aged↗
PubMed1997

Convenient and reversible site-specific targeting of exogenous DNA into a bacterial chromosome by use of the FLP recombinase: the FLIRT system.

We have created a system that utilizes the FLP recombinase of yeast to introduce exogenous cloned DNA reversibly at defined locations in the Escherichia coli chromosome. Recombination target (FRT) sites can be introduced permanently at random locations in the chromosome on a modified Tn5 transposon, now designed so that the inserted FRT can be detected and its location mapped with base pair resolution. FLP recombinase is provided as needed through the regulated expression of its gene on a plasmid. Exogenous DNA is introduced on a cloning vector that contains an FRT, selectable markers, and a replication origin designed to be deleted prior to electroporation for targeting purposes. High yields of targeted integrants are obtained, even in a recA background. This system permits rapid and precise excision of the introduced DNA when needed, without destroying the cells. The efficiency of targeting appears to be affected only modestly by transcription initiation upstream of the chromosomal FRT site. With rare exceptions, FRTs introduced to the bacterial chromosome are targeted with high efficiency regardless of their location. The system should facilitate studies of bacterial genome structure and function, simplify a wide range of chromosomal cloning applications, and generally enhance the utility of E. coli as an experimental organism in biotechnology.

Blotting, Southern↗
PubMed1995

Emergency needlestick injury.

During the course of a year, there are many healthcare workers nationwide who sustain sharps injuries whilst carrying out their duties. Staff who work in the Accident and Emergency (A & E) units are no different from anyone else in this respect. The emotional cost of such an accident cannot be calculated, whereas the financial costs can. This article aims to show how the cost of an injury to a member of staff can be calculated, thus allowing a manager to assess the financial implications of sharps injuries to their department. In the absence of access to an Occupational Health (OH) department, most A & E units have to respond to sharps injuries to healthcare workers in the hospital. This task must be attended to by the medical staff as well as the nursing staff of the A & E unit. Within the following text the appropriate responses and methods to ensure uniformity of response are discussed. The tables and the calculation figures shown are taken directly from the information held in the St James's University Hospital Trust's OH department. All calculations are based on the middle band of the salary scale for each discipline. Accurate costings for each member of staff injured cannot be shown in this article, but the general principle is laid down and can be easily followed for any situation.

Emergency Service, Hospital↗
PubMed1994

RuvA and RuvB proteins facilitate the bypass of heterologous DNA insertions during RecA protein-mediated DNA strand exchange.

RecA protein-mediated DNA strand exchange between circular single-stranded DNA and linear duplex DNA readily bypasses short (up to 100 base pairs) heterologous inserts in one of the DNA substrates. Larger heterologous inserts are bypassed with decreasing efficiency, and inserts larger than 200 base pairs substantially block RecA-mediated DNA strand exchange. The RuvA and RuvB proteins dramatically facilitate the bypass of larger heterologous inserts. When the RuvA and RuvB proteins are added to an ongoing RecA protein-mediated strand exchange reaction, interior heterologous inserts of 1 kilobase pair are bypassed at significant frequencies. The RuvA, RuvB, and RecA proteins are all required for this activity. Bypass occurs only when homologous sequences are present on both sides of the insert. When the heterologous insert is positioned at either end of the linear duplex substrate, the RuvA and RuvB proteins do not significantly increase product formation in RecA protein-mediated DNA strand exchange reactions. The results suggest an important role for RuvA and RuvB in the bypass of DNA structural barriers during recombinational DNA repair.

Adenosine Triphosphate↗
PubMed1991

A bacterial model system for chromosomal targeting.

A system that permits efficient site-specific chromosomal targeting of foreign DNA on the Escherichia coli chromosome has been developed, using the FLP site-specific recombination system derived from the yeast 2 mu plasmid. The system demonstrates the feasibility of using site-specific recombination for this purpose, and provides a means to gather information on parameters that may affect chromosomal targeting to guide efforts to establish similar systems in higher eukaryotes. In this model system, the efficiency of integration of foreign DNA is affected by the location of the target site in the chromosome, and the structure of the recombination sites.

Base Sequence↗
PubMed1989

Genetic derepression of a developmentally regulated lipopolysaccharide antigen from Rhizobium leguminosarum 3841.

Monoclonal antibody AFRC MAC 203 recognizes a developmentally regulated lipopolysaccharide antigen in Rhizobium leguminosarum bv. viciae 3841. Transposon-induced mutants that constitutively expressed MAC 203 antigen were isolated. These strains were morphologically normal, showed no gross abnormalities in lipopolysaccharide size distribution on sodium dodecyl sulfate-polyacrylamide gels, and induced normal nitrogen-fixing nodules. However, the mutants lacked lipopolysaccharide epitopes recognized by another rat monoclonal antibody, AFRC MAC 281, suggesting that the corresponding epitopes may be interconverted or share a common precursor. In conjugational crosses, the transposon insertion associated with both the loss of MAC 281 antigen and the constitutive expression of MAC 203 antigen showed linkage to the chromosomal rif allele. A derivative of strain 3841 with a deletion spanning the nod-fix region of the symbiotic plasmid showed no altered expression pattern for MAC 203 antigen, suggesting that the relevant genetic determinants map to genomic sites that are not associated with nifA or any known genes on the symbiotic plasmid.

Antibodies, Monoclonal↗
PubMed1987

Purification of the FLP site-specific recombinase by affinity chromatography and re-examination of basic properties of the system.

The FLP protein, a site-specific recombinase encoded by the 2 micron plasmid of yeast, has been purified to near homogeneity from extracts of E. coli cells in which the protein has been expressed. The purification is a three column procedure, the final step employing affinity chromatography. The affinity ligand consists of a DNA polymer with multiple FLP protein binding sites arranged in tandem repeats. This protocol yields 2 mg of FLP protein which is 85% pure. The purified protein is highly active, stable for several months at -70 degrees C and free of detectable nucleases. The molecular weight and N-terminal sequence are identical to that predicted for the FLP protein by the DNA sequence of the gene. Purified FLP protein primarily, but not exclusively, promotes intramolecular recombination. Intermolecular recombination becomes the dominant reaction when E. coli extracts containing no FLP protein are added to the reaction mixture. These extracts are not specifically required for recombination, but demonstrate that some properties previously attributed to FLP protein can be assigned to contaminating proteins present in E. coli.

Affinity Labels↗
PubMed1986

Physical association between the peribacteroid membrane and lipopolysaccharide from the bacteroid outer membrane in Rhizobium-infected pea root nodule cells.

Monoclonal antibodies were used as cytochemical markers to study surface interactions between endosymbiotic Rhizobium bacteroids from pea root nodules and the encircling peribacteroid membranes, which are of plant origin. Monoclonal antibodies that react with Rhizobium lipopolysaccharide (LPS) or with a plant membrane glycoprotein were used as markers for material from the bacteroid outer membrane or the peribacteroid membrane, respectively. Membrane-enclosed bacteroids were isolated from nodule homogenates by sucrose gradient centrifugation, and the encircling peribacteroid membrane was released by mild osmotic shock treatment. Using an immunochemical technique (sandwich ELISA), it was shown that 1-5% of the LPS antigen released into the peribacteroid fraction by mild osmotic shock treatment was physically associated with peribacteroid membrane through a detergent-sensitive linkage. This association could be visualized when freshly prepared peribacteroid material was immobilized on gold grids and examined by electron microscopy after dual antibody immunogold treatment and subsequent negative staining. The distribution of LPS antigen within infected nodule cells was also investigated by immunogold staining for thin sections of nodule tissue fixed in glutaraldehyde, and a close association between LPS antigen and peribacteroid membrane was often seen.

Cell Membrane↗
PubMed1985

Characterization of fatty acid synthetase cDNA clone and its mRNA.

Four cDNA clones have been identified by hybrid-select translation to contain the sequences complementary to fatty acid synthetase mRNA. The restriction mapping of these clones indicated that three of these, pFAS-7, pFAS-17 and pFAS-18, have sequences in common, and a fourth, pFAS-15, did not hybridize with the others, suggesting sequence to another region of the mRNA. Northern analysis of cytoplasmic poly(A) +RNA showed the presence of two bands at 9.2 Kb and 8.4 Kb. Similar analysis of nuclear RNA also showed the presence of two bands at 14 and 11 Kb. These probably represent unprocessed transcripts. Southern analysis of genomic DNA digested with EcoRI, BamHI, HindIII and PstI indicate the presence of a single gene copy for fatty acid synthetase.

Animals↗