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Biomedical subjects

R Waugh

Publications and source records attributed to R Waugh.

At least 109 records · Page 6Linked to original sources
PubMed1992

Molecular characterisation of inter- and intra-specific somatic hybrids of potato using randomly amplified polymorphic DNA (RAPD) markers.

Protoplast fusion allows the transfer of both mono- and polygenic traits between species that are sexually incompatible. This approach has particular relevance for potato, and somatic hybridisation has been used to introduce a range of disease resistance genes from sexually incompatible wild species into the cultivated potato gene pool. In addition, protoplast fusion allows the resynthesis of tetraploid genotypes from preselected diploid or dihaploid donor parents. A limiting factor for the efficient exploitation of this technology in potato breeding is the difficulty of unequivocally identifying nuclear hybrids (heterokaryons). In order to facilitate the identification of hybrids at an early stage following fusion, Randomly Amplified Polymorphic DNA markers (RAPDs) have been used to characterise molecularly both inter- and intra-specific somatic hybrids of potato. RAPD markers detect naturally occurring polymorphism in the donor genotypes and utilise short oligonucleotide primers of arbitrary nucleotide sequence in combination with the polymerase chain reaction (PCR). The exploitation of RAPDs in the characterisation of both somatic and sexual hybrids is discussed.

Base Sequence↗
PubMed1992

Detection of genetic variation between and within populations of Gliricidia sepium and G. maculata using RAPD markers.

Gliricidia sepium and G. maculata are multi-purpose leguminous trees native to Central America and Mexico. Research programmes have been initiated to define the native distribution of Gliricidia and sample the spectrum of genetic variation. To date, there has been little systematic assessment of genetic variability in multi-purpose tree species. Accurate estimates of diversity between- and within-populations are considered a prerequisite for the optimization of sampling and breeding strategies. We have used a PCR-based polymorphic assay procedure (RAPDs) to monitor genetic variability in Gliricidia. Extensive genetic variability was detected between species and the variability was partitioned into between- and within-population components. On average, most (60 per cent) of the variation occurs between G. sepium populations but oligonucleotide primers differed in their capacity to detect variability between and within populations. Population-specific genetic markers were identified. RAPDs provide a cost-effective method for the precise and routine evaluation of variability and may be used to identify areas of maximum diversity. The approaches outlined have general applicability to a range of organisms and are discussed in relation to the exploitation of multi-purpose tree species of the tropics.

Americas↗
PubMed1992

Association between rDNA alleles and quantitative traits in doubled haploid populations of barley.

Doubled haploids (DH) were generated from reciprocal F1 hybrids which were heterozygous for alleles at the Nor-H3 locus on chromosome 5H of barley. The r-DNA alleles did not deviate significantly from the expected 1:1 ratio and the DH progenies were classified into two groups based on the allelic constitution of the Nor-H3 locus. The DHs were grown in a randomized, replicated field experiment and a range of agronomic and quality traits were recorded. The Nor-H3 locus was associated with a significant portion of the genetic variation for: yield, thousand corn weight, water sensitivity and milling energy requirement of the grain. However, the magnitude of the differences between groups was dependent on the direction of the cross. The milling energy requirement of the grain was consistently associated with alleles at the Nor-H3 locus. These results are presented in relation to the dynamics of rDNA evolution and variability. The potential of molecular markers in conjunction with doubled haploids to map quantitative traits in barley is also discussed.

Alleles↗
PubMed1992

Successful reversal of primary graft non-function in a liver transplant patient treated with prostaglandin E1.

A 63 year old woman with liver failure received a transplant from a 21 year old male diagnosed as brain dead following a motor accident. After the operation, bile production was virtually absent and aspartate transaminase (AST) values rose dramatically 40 h postoperatively. Primary non-function of the graft was diagnosed, and the patient put on an urgent list for retransplantation. At the same time a continuous intravenous infusion of PGE1 was administered. Aspartate transaminase levels decreased within 9 h and reached normal levels by the sixth postoperative day, when bile production began to increase. Liver function subsequently returned to normal.

Alprostadil↗
PubMed1992

Venous occlusion: a rare complication of transvenous cardiac pacing.

Venous occlusion is an uncommon complication of transvenous cardiac pacing. Fibrotic occlusion of the right subclavian and innominate veins and stenosis of the left innominate vein, after the insertion of transvenous pacing wire, was corrected surgically with an external iliac vein graft.

Adult↗
PubMed1991

Cloning and characterisation of a U6 small nuclear RNA gene from potato.

Using a mixed U6 snRNA gene probe and a low stringency hybridization procedure we have isolated a U6 snRNA containing clone from a potato genomic library in lambda EMBL 3. This clone contains a single U6 snRNA gene which has been subcloned and sequenced. Southern blotting experiments using this gene and the heterologous U6 genes as probes indicate that the potato U6 gene family consists of more than 20 members. The potato U6 gene sequence shows high identity to previously characterised plant U6 snRNA gene sequences and possesses correctly positioned and spaced transcription control elements suggesting that it is an active gene.

Base Sequence↗
PubMed1991

Sequence variation and linkage of potato U2snRNA-encoding genes established by PCR.

Plant uridylate-rich small nuclear RNA (UsnRNA)-encoding genes (UsnRNA) are present as multigene families exhibiting greater sequence variation than has been described in animal UsnRNA families. The potato U2snRNA multigene family has 25 to 40 potential gene members. Four gene variants have been analysed to date, two of which are linked. In order to investigate U2snRNA expression in potato in terms of the function of such sequence variation in development, the degree of sequence variation in both the coding region and flanking regions in this gene family must be assessed. On the assumption that at least some U2snRNA genes are linked, a polymerase chain reaction (PCR) approach, using primers designed to amplify intergenic nucleotide sequences including coding and 5' flanking regions, has been devised. Six new U2snRNA gene variant sequences and one U2snRNA pseudogene sequence have been generated. In addition, six new flanking region sequences have been produced which, in contrast to other plant UsnRNA gene families, show considerable variation in the important upstream sequence element. This PCR approach may be applicable to the analysis of genomic organisation and sequence variation of other multigene families.

Base Sequence↗
PubMed1991

Evolutionary conservation of the spliceosomal protein, U2B''.

U1 and U2snRNPs play key roles in pre-mRNA splicing. The interactions between the U1 and U2snRNP-specific proteins, U1A, U2A' and U2B'' and their respective UsnRNAs are of interest both to elucidate their roles in splicing, and as models to study RNA-protein interactions. We have cloned a full-length cDNA, encoding U2B'', from potato. This is the first report of a sequence for a plant UsnRNP protein. The plant U2B'' sequence exhibits extensive similarity with the human U2B'' protein at both the DNA and amino acid levels. The evolutionary conservation at the protein level, particularly in sequences implicated in determining specific binding to U2snRNA, suggests conservation of U2B'' function from plants to man. The significance of amino acid substitutions in the RNP-80 motif with respect to U2snRNA binding in plants is discussed.

Amino Acid Sequence↗
PubMed1991

Sequence and expression of potato U2 snRNA genes.

Plant UsnRNA multigene families show a high degree of sequence variation among individual gene members. The potato U2snRNA gene family consists of between twenty-five and forty genes. Four potato U2snRNA gene variants have been isolated. Despite the sequence variation in coding and flanking regions, all maintain the conserved U2snRNA secondary structure and all contain the plant UsnRNA promoter elements: the upstream sequence element (USE) and TATA-like box in the -70 and -30 regions respectively. In RNase A/T1 protection analyses, one of the genes, PotU2-22, protected high levels of full length U2snRNA transcripts in potato leaf, stem, root and tuber RNA. Thus, PotU2-22 or genes with identical coding regions, are highly expressed in these potato organs and therefore represent a major subset of functional U2snRNA genes. Similar expression levels of the PotU2-22 sequence variant were also found in four genetically different potato cultivars and also in tobacco, a species closely related to potato, suggesting conservation of the coding regions of expressed U2snRNA genes. A second gene, PotU2-4, protected very low levels of full length transcripts while a third gene, PotU2-11, was not expressed in the potato organs analysed. The relative expression levels of the gene variants may reflect individual gene differences in, for example, the USE and TATA regulatory elements, or variations in gene copy number.

Animals↗
PubMed1991

Percutaneous urinary diversion in gynecologic oncology.

During the 10-year period after 1979, percutaneous urinary diversion (PCUD) was performed on 35 patients whose mean age was 53.5 years (30-80 years). Twenty-one patients (60%) had Stage IIB-IV cervical cancer, 11 (31%) Stage IB-IIA cervical cancer, 2 (6%) Stage IB-II endometrial cancer, and 1 (3%) Stage IB vaginal cancer. All had radiological evidence of ureteric obstruction and 8 patients also had urinary tract fistulae. Serum creatinine levels were elevated in 24. Following diversion there was a significant fall in mean pretreatment creatinine levels from 482 mumol/liter (range, 70-1703 mumol/liter) to 131 mumol/liter (range, 60-290 mumol/liter; P less than 0.0001); those patients with normal creatinine levels prior to diversion also had a reduction in their levels. A significant fall in mean serum urea levels from 22.0 mmol/liter pre- to 11.9 mmol/liter post-PCUD (P less than 0.001) was also noted. Minor complications occurred and included hemorrhage, replacement/reinsertion, infection, and blockage. Median survival of the 35 patients after PCUD was 6 months (mean, 16.5 months). For the 11 with normal pretreatment renal function median survival was 16 months (mean, 41 months) compared to 2.5 months (mean, 5.1 months) for those with elevated pretreatment serum creatinine levels. Median survival with untreated malignancy was 7 months (mean, 19.6 months) and 6 months (mean, 12.3 months) in patients with previously treated cancer. PCUD is indicated in previously untreated patients with gynecologic cancer so that primary therapy can be instituted. The role of urinary diversion in patients with previously treated cancer must be individualized. Palliative diversion is appropriate in selected patients where additional therapy is expected to prolong life, where symptom control is needed, or to allow the patient to return home for a significant proportion of the remainder of life.

Adult↗
PubMed1990

Plant UsnRNA genes.

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Cloning, Molecular↗
PubMed1990

Electric fields induce reversible changes in the surface to volume ratio of micropipette-aspirated erythrocytes.

Micropipette-aspirated erythrocytes exhibit reversible changes in sphericity (surface-to-volume ratio) in response to applied electric fields. The potentials were applied between the shaft of the pipette and the bathing medium using Ag-AgCl electrodes and current clamping electronics. The change in surface-to-volume ratio is evidenced as a reversible change in the length of the cell projection in the pipette at constant aspiration pressure and changing voltage. The magnitude of the changes decreased in proportion to the inverse of the solute concentration indicating that the change in sphericity was due to a change in cell volume. Reversible changes in projection length equivalent to a 10% change in cell volume were observed to occur over times on the order of 10 s. The magnitude and time course of the effect were not affected by the removal of intracellular hemoglobin or inhibition of anion exchange. The effect was reduced by the presence of lanthanum and other multivalent cations in the suspending solution, suggesting that surface charge may play a role in mediating the effect.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1990

Alterations of the apparent area expansivity modulus of red blood cell membrane by electric fields.

Red blood cell membrane exhibits a large resistance to changes in surface area. This resistance is characterized by the area expansivity modulus K, which relates the isotropic membrane force resultant, T, to the fractional change in membrane surface area delta A/Ao. The experimental technique commonly used to determine K is micropipette aspiration. Using this method, E. A. Evans and R. Waugh (1977, Biophys. J. 20:307-313) obtained a value of 450 dyn/cm for the modulus. In the present report, it is shown that the value of K, as determined using this method, is affected by electric potential differences applied across the tip of the pipette. Using Ag-AgCl electrodes and current clamping electronics, we obtained values for K ranging from 150 dyn/cm with -1.0 V applied, to 1,500 dyn/cm with 1.0 V applied. At 0.0 V the modulus obtained was approximately 500 dyn/cm. A reversible, voltage- and pressure-dependent change in the cell volume probably accounts for the effect of the voltage on the calculated value of the modulus. The use of lanthanum chloride or increasing the extra- and intracellular solute concentrations reduced the voltage dependence of the measurements. It was also found that when dissimilar metals were used to "ground" the pipette to the chamber to prevent lysis of cells by static charge, values for K ranged from 121 to 608 dyn/cm. Based on measurements made at zero applied volts, in the presence of 0.4 mM lanthanum and at high solute concentration, we conclude that the true value of the modulus is approximately 500 dyn/cm.

Blood Specimen Collection↗
PubMed1990

The effect of various hearing protectors on sound localization in the horizontal and vertical planes.

Listeners were tested under free head/torso movement conditions, using a brief pulsed broadband noise signal presented from any 1 of 20 loudspeakers in two intersecting hemicircumferential arrays: one in the horizontal plane, one in the vertical. The listeners' task was to judge the whereabouts of each signal while listening in normal, open-ears conditions or while wearing various types of standard or electronic earmuffs or compressible foam earplugs. Results showed that listeners could accomplish the task successfully in normal (open-ear) conditions. Results using earplugs, nonelectronic earmuffs, and two types of dichotic (dual microphone) electronic earmuffs showed decrements in performance similar to each other. These decrements took the general form of loss of appreciation of the vertical plane and of front-rear differences in the horizontal plane. Lateral discrimination was blurred but otherwise intact. Of two diotic (single microphone) electronic earmuffs, one completely disrupted localization function and the other came close to it.

Auditory Perception↗
PubMed1989

Maize U2 snRNAs: gene sequence and expression.

The complexity of plant U-type small nuclear ribonucleoprotein particles (UsnRNPs) may represent one level at which differences in splicing between animals and plants and between monocotyledonous and dicotyledonous plants could be effected. The maize (monocot.) U2snRNA multigene family consists of some 25 to 40 genes which from RNA blot and RNase protection analyses produce U2snRNAs varying in both size and sequence. The first 77 nucleotides of the maize U2-27 snRNA gene are identical to U2snRNA genes of Arabidopsis (dicot). Despite much lower sequence homology in the remaining 120 nucleotides the secondary structure of the RNA is conserved. The difference in splicing between monocot. and dicot. plants cannot be explained on the basis of sequence differences between monocot, and dicot. U2snRNAs in the region which may interact with intron branch point sequences.

Base Sequence↗
PubMed1989

Nickel deficiency gives rise to the defective hydrogenase phenotype of hydC and fnr mutants in Escherichia coli.

Hydrogenase activity and other hydrogenase-related functions can be restored to hydC mutants by the specific addition of nickel salts to the growth medium. These mutants are defective in all three hydrogenase isoenzymes and the restoration is dependent upon protein synthesis. The cellular nickel content of the mutant when grown in LB medium is less than 1% of that of the parental strain. Partial suppression of the hydrogenase phenotype of hydC mutants occurs when growth takes place in a different medium. This correlates with an increased cellular nickel content. The phenotype of the mutant is also fully suppressed by growth in media of very low magnesium content. Such media facilitate nickel uptake via the magnesium transport system, which leads to the acquisition of a normal cellular nickel content. Mutations in the fnr gene, which encodes a transcriptional regulator for several anaerobically expressed enzymes, abolishes hydC expression and gives rise to a defective hydrogenase phenotype. The hydrogenase phenotype of fnr is closely similar to that of hydC in all respects examined. The hydrogenase activity of fnr strains can be restored by the presence of a functional hydC gene on a multicopy plasmid. The hydrogenase phenotype of fnr strains therefore arises indirectly via suppression of hydC, which leads to a low cellular nickel content. Nickel has no influence on fumarate reductase or nitrate reductase activities in fnr strains. The hydrogen-metabolism phenotype of fnr strains is, therefore, dependent upon their ability to acquire nickel from growth media. It is likely that hydC encodes a specific transport system for nickel.

Escherichia coli↗