Biomedical subjects

R Waugh

Publications and source records attributed to R Waugh.

At least 91 records · Page 5Linked to original sources

PubMed1994

Molecular characterisation of plant U14 small nucleolar RNA genes: closely linked genes are transcribed as polycistronic U14 transcripts.

U14snoRNAs are highly conserved eukaryotic nucleolar small RNAs involved in precursor ribosomal RNA processing. In vertebrates, U14snoRNAs and a number of other snoRNAs are transcribed within introns of protein coding genes and are released by processing. We have isolated potato and maize genomic U14 clones using PCR-amplified plant U14 probes. Plant U14s show extensive homology to those from yeast and animals but contain plant-specific sequences. One of the isolated maize clones contains a cluster of four U14 genes in a region of only 761 bp, confirming the close linkage of U14 genes in maize, potato and barley as established by PCR. The absence of known plant promoter elements, the proximity of the genes and the detection of transcripts containing linked U14s by RT-PCR indicates that some plant U14snoRNAs are transcribed as precursor RNAs which are then processed to release individual U14s. Whether plant U14snoRNAs are intron-encoded or transcribed from novel promoter sequences, remains to be established.

Base Sequence↗

PubMed1994

Characterisation of a complementary DNA encoding a novel plant enzyme with sucrolytic activity.

The cloning of a 1332 bp cDNA from a potato (Solanum tuberosum L.) cv. Cara leaf cDNA expression library, using an antibody raised against a purified tuber protein preparation with sucrolytic activity, is described. The corresponding gene in potato is of low copy number, is expressed in a variety of tissues, and encodes a protein which includes several domains with similarity to database sequences, including ferredoxin from Clostridium pasteurianum. Expression of the cDNA in E. coli yields a fusion protein with sucrolytic activity.

Amino Acid Sequence↗

PubMed1994

Value of transthoracic echocardiography in predicting embolic events in active infective endocarditis. Duke Endocarditis Service.

The purpose of this study was twofold: (1) to determine interobserver variability of echocardiographic characteristics of vegetations in patients with infective endocarditis, and (2) to assess the value of these vegetation characteristics in predicting embolic events. Although echocardiography contributes to the diagnosis of patients with infective endocarditis, its prognostic role in predicting embolic events is controversial. The echocardiograms of 41 patients with infective endocarditis were independently reviewed by 4 echocardiographers blinded to the clinical data. If a vegetation was present, the following characteristics were analyzed: involved site, size, mobility, shape, and pedunculated or sessile attachment. Each echocardiographer also made a "gestalt" estimate of embolic risk based on these vegetation characteristics. Interobserver agreement on vegetation characteristics and their relation to embolic events was then determined using kappa statistics and logistic regression analysis. Interobserver agreement was 98% with regard to echocardiographic vegetation presence and 97% with regard to the involved site. Of the 30 patients in whom vegetations were observed, complete observer agreement was achieved with regard to size in 22 (73%), mobility in 17 (57%), shape in 11 (37%), and attachment in 12 (40%). Vegetations with a maximal diameter of > 10 mm were associated with a 50% incidence of embolic events, compared with a 42% incidence of emboli in patients with vegetations measuring < or = 10 mm. Interobserver variability was great with respect to vegetation shape, mobility, and attachment characteristics. Echocardiographic vegetation characteristics were not helpful in defining the risk of embolic complications in patients with endocarditis.

Echocardiography, Transesophageal↗

PubMed1994

Potato (Solanum tuberosum) invertase-encoding cDNAs and their differential expression.

A full-length cDNA clone encoding a potato invertase (Inv) has been isolated. It is highly related (77% nucleotide identity) to a previously characterised potato cDNA clone encoding a putative extracellular Inv. These Inv genes encode a subfamily of apoplastic enzymes which are shown to be distinct, on the basis of sequence similarity, from the related subfamily of vacuolar enzymes. In order to differentiate between the expression of the two potato genes encoding apoplastic Inv, a single-stranded conformational polymorphism (SSCP) assay was developed for products generated by reverse transcription-polymerase chain reaction (RT-PCR) utilising primers designed to amplify both potato sequences. Using this approach, we have shown that these two identified Inv from potato are expressed in a tissue-specific and developmentally regulated manner.

Amino Acid Sequence↗

PubMed1994

Treatment of complex abdominal aortic aneurysms by a combination of endoluminal and extraluminal aortofemoral grafts.

PURPOSE: The purpose of this study was to test the hypothesis that abdominal aortic aneurysms (AAA) whose morphology makes them unsuited for repair with an endoluminal tube graft can be treated by a combination of a transluminally placed aortofemoral graft and a femorofemoral crossover graft. In addition the technique involves either ligation or balloon occlusion of the contralateral common iliac and internal iliac arteries in such a manner that excludes the AAA from the circulation. METHODS: We report the use of this technique in three male patients with 6.4 to 7.0 cm diameter AAA. Two had renal impairment and cardiac function too poor to permit open repair, and the third had an unfavorable abdomen caused by previous surgery and the presence of a permanent colostomy. Each patient had an individually tailored Dacron tube graft constructed on the basis of preoperative arteriograms and computed tomography scans. The grafts were delivered transluminally into the aorta through a sheath in the iliac arteries and anchored proximally with a stainless steel stent under radiographic control. The grafts were then anastomosed distally to the femoral artery. RESULTS: Recovery was complicated by a midgraft stenosis corrected by percutaneous balloon dilation in one patient, an episode of pulmonary edema in the second and an unexplained pyrexia in the third. Follow-up with duplex scanning confirmed normal flow through the grafts and the presence of thrombus between the prosthetic graft and the aneurysmal sac. CONCLUSIONS: We conclude that transluminal placement of an aortofemoral graft combined with a femorofemoral crossover graft is feasible in patients who are unsuited to repair with an endoluminal tube graft. The outcome with this technique is not known and requires further careful evaluation.

Aged↗

PubMed1994

Complementary deletions in expressed potato U2snRNA gene variants support the hypothesis that stem-loop IIb is dispensable for splicing.

A polymerase chain reaction (PCR) strategy designed to amplify DNA sequences between closely linked U2snRNA genes has generated extensive coding and 5' regulatory sequence information on the potato U2snRNA multigene family. Two of the U2snRNA coding sequences isolated differed substantially from normal U2snRNAs by containing both complementary deletions and regions of novel sequence. However, sequences such as Sm-binding sites and loops of stem-loops III and IV, which are some of the most highly conserved regions in U2snRNA, remain highly conserved in these genes. The complementary deletions would effectively remove stem-loop IIb which has been shown in yeast to be unnecessary for pre-mRNA splicing. Transcripts from one of the genes have been detected by reverse transcriptase-PCR (RT-PCR) in total RNA. These novel U2snRNA genes represent the first reported example of naturally occurring structural variants and provide support for the proposed non-essential role of U2snRNA stem-loop IIb.

Base Sequence↗

PubMed1994

A multiyear workplace-monitoring program for refractory ceramic fibers.

This paper summarizes interim results of a 5-year workplace monitoring program conducted by firms belonging to the Refractory Ceramic Fibers Coalition (RCFC) pursuant to a Consent Agreement with the U.S. EPA. The exposure monitoring program is part of a model Product Stewardship Program (PSP) developed by RCFC. This paper reviews the refractory ceramic fiber (RCF) industry, findings of animal bioassay and epidemiological investigations, and the regulatory approach used by EPA. The scope, protocols, sample collection budgets, and experimental design of the monitoring program are summarized. In brief, the program will gather 720 time-weighted average (TWA) workplace concentration measurements annually, partitioned among 8 functional job classifications, both from plants that manufacture and from those that process or use RCF. Statistical analyses reveal that: workplace airborne RCF concentration data are approximately log-normally distributed, 93% of workplace TWAs are beneath the industry's recommended exposure guideline of 1 fiber per cubic centimeter (f/cc), there are significant differences in average workplace RCF concentrations among job types, and PSP activities are effective in lowering workplace exposure. Results of this effort provide an interesting illustration of a successful cooperative effort between a responsible industry and regulatory agencies.

Animals↗

PubMed1994

Detection of deep venous thrombi and pulmonary embolus with technetium-99m-DD-3B6/22 anti-fibrin monoclonal antibody Fab' fragment.

UNLABELLED: Technetium-99m-labeled anti-fibrin DD-3B6/22 Fab' monoclonal antibody fragments, which specifically target human cross-linked fibrin with high affinity, were evaluated in humans for safety and their capacity to detect deep vein thrombi and pulmonary embolism. METHODS: Twenty patients with proven deep-vein thrombosis, documented by contrast venography, or venous duplex scan, were injected with a 600 MBq (0.5 mg) dose of antibody. Planar images of the lower limbs were recorded at 0, 2, 6 and 24 hr and chest scintigrams were recorded at 6 and 24 hr. RESULTS: All venography documented thrombus sites, calves, popliteal and femoral, were detected with the radioimmunoconjugate. For the venous duplex scan-proven thrombus sites, all except two calf thrombi in two patients with bilateral disease and other positive sites were detected. Five patients had bilateral deep-vein thrombosis with multiple sites being visualized with the radioimmunoconjugate in the calf, popliteal and femoral regions. One case of pulmonary embolus was also definitively demonstrated. Documented thrombus sites were detected at 2 and 6 hr postinjection. Nineteen patients were on heparin. No adverse reactions to the injected dose were observed and one low titer human anti-mouse antibody response may have occurred. CONCLUSION: The results indicate that 99mTc-DD-3B6/22 Fab' has potential for noninvasive detection of deep-vein thrombosis and pulmonary embolism.

Adult↗

PubMed1993

Detection of a plant protein analogous to the yeast spliceosomal protein, PRP8.

We have investigated whether a spliceosomal protein analogous to the yeast protein, PRP8, was present in higher plants. A protein with a molecular weight > 200 kDa was detected in Western blots of tobacco (Nicotiana tabacum L.) nuclear extracts with affinity-purified antibodies, raised against four different beta-galactosidase-PRP8 fusion proteins. The < 200 kDa protein was also immunoprecipitated by antibodies against the snRNA-specific trimethylguanosine cap structure and was, therefore, snRNP-associated. The presence of this protein in plants, in addition to yeast, Drosophila and humans, and the conservation of large size and epitopes highlights the importance of PRP8 in pre-mRNA splicing.

Blotting, Western↗

PubMed1993

The U6 small nuclear RNA gene family of potato.

Using the inverse polymerase chain reaction (IPCR), 19 U6snRNA gene promoters were isolated from the potato genome. Analysis of their nucleotide sequences revealed the existence of two subfamilies. Promoters from class 1 harbour the typical sequence elements required for plant snRNA gene transcription whereas those from class 2 do not have a TATA box. Three promoters were fused to a modified U6snRNA-coding sequence to allow their activity to be monitored in tobacco protoplasts. Two of the promoters, one from either class, were found to be active. Comparison of potato U6snRNA gene promoter sequences with those found in other plant species showed various degrees of homology. In addition, the entire nucleotide sequences of seven potato U6snRNA genes and one pseudogene were determined. The overall frequency of nucleotide changes after PCR was found to be 1.15 x 10(-3). The mutations appeared to be clustered in a distinct area and were all A-to-G/T-to-C substitutions.

Base Sequence↗

PubMed1993

cDNA cloning and expression of a potato (Solanum tuberosum) invertase.

A cDNA clone encoding an invertase isoenzyme has been isolated from a potato leaf cDNA library. The deduced amino acid sequence shows significant similarities to previously characterised invertases. The highest degree of overall similarity, including the signal peptide sequence, is to carrot cell wall invertase, suggesting that the potato gene encodes an apoplastic enzyme. Expression of the gene, as determined by RT-PCR, is detected in stem and leaf tissue, and at lower levels in tuber, but is absent from roots.

Amino Acid Sequence↗

PubMed1993

Differential expression of U5snRNA gene variants in maize (Zea mays) protoplasts.

The small nuclear ribonucleoprotein particles U1, U2, U4/U6 and U5 participate in the removal of introns from pre-messenger RNAs in the nucleus. Three genes encoding U5snRNAs, the RNA moiety of U5snRNPs, have been isolated from maize. As in other plant UsnRNA gene families the three maize U5snRNA genes exhibit sequence variation. Two of the gene variants (MzU5.1 and MzU5.2) are clearly expressed after transfection into maize leaf protoplasts while the third gene variant (MzU5.3) is expressed at very low levels. These different levels of expression cannot be directly correlated with sequence changes in the highly conserved Upstream Sequence Element (USE) required for expression of Arabidopsis UsnRNA genes nor with differential stability of the U5snRNA transcripts. Further sequence elements may therefore have a role in regulating maize UsnRNA gene expression.

Base Sequence↗

PubMed1993

Identification of RAPD markers linked to a Rhynchosporium secalis resistance locus in barley using near-isogenic lines and bulked segregant analysis.

Three hundred random sequence 10-mer primers were used to screen a pair of near-isogenic lines of barley and their donor parent for markers linked to genes conferring resistance to Rhynchosporium secalis. One primer was identified which reproducibly generated a product, SC10-65-H400, from the donor parent and the Rhynchosporium-resistant near-isogenic line but not from the recurrent parent. Segregation analysis on a barley doubled haploid population and examination of a further three near-isogenic lines, their donor and recurrent parents confirmed that this marker was linked to the Rhynchosporium resistance locus (Rh) on chromosome 3L. The presence or absence of SC10-65-H400 was subsequently used along with the resistance phenotype to identify two groups of individuals in the doubled haploid population which possessed alternative alleles at both loci and defined a genetic interval between these two markers. Based on that information two bulked DNA samples were constructed by combining equal amounts of DNA from five individuals from each group. The two bulks and doubled haploid parental lines were screened with 700 10-mer primers. Seven products were identified which were present in the 'resistant' bulk and parent and were absent in the susceptible samples. Segregation analysis established their association with Rh. In addition co-segregation of the linked markers with a set of chromosome arm specific RFLPs confirmed the location of the Rh locus on the long arm of barley chromosome 3.

Base Sequence↗

PubMed1993

Genetic differentiation of cocoa (Theobroma cacao L.) populations revealed by RAPD analysis.

In order to preserve and exploit the valuable genetic resources of tropical forest trees, such as cocoa, a systematic assessment of the available genetic variability is necessary. The approach we have used is based on a simple mini-prep DNA extraction procedure together with a polymerase-chain-reaction- (PCR)-based polymorphic assay procedure (RAPD). Twenty-five cocoa accessions: IMCs and PAs collected from Peru and LCTEENs collected from Ecuador, which are difficult to distinguish using morphological or biochemical descriptors, were uniquely fingerprinted using a minimum of three oligonucleotide primers. Analysis of the variability detected using RAPDs clearly discriminated between the geographical origin of the three cocoa populations. Partitioning of variability into within and between population components revealed that most variation was detected within a population. The potential of RAPD analysis to facilitate the rationalization of field gene banks and provide accurate estimates of diversity to allow optimization of collecting strategies is discussed.

Base Sequence↗

PubMed1993

Detection and analysis of genetic variation in Hordeum spontaneum populations from Israel using RAPD markers.

Randomly amplified polymorphic DNA (RAPD) markers were used to analyse genetic diversity within and between Hordeum spontaneum populations sampled from Israel. Nei's index of genetic differentiation was used to partition diversity into within and between population components. Fifty-seven per cent of the variation detected was partitioned within 10 H. spontaneum populations. Using principal component and multiple regression analysis, part of the variation detected between populations was seen to be associated with certain ecogeographical factors. Fifty-eight per cent of the distribution of the phenotypic frequencies of three RAPD phenotypes detected using a single primer in 20 H. spontaneum populations could be accounted for by four ecogeographical variables, suggesting adaptive variation at certain RAPD loci.

Alleles↗

PubMed1993

Visualisation of arterial structure in vivo with intravascular ultrasound.

BACKGROUND: Contrast angiography provides a silhouette of the arterial lumen, but does not give information about arterial wall structure. Catheter-tip ultrasound transducers can now provide a cross-sectional image of the arterial wall. This study examined the pathological correlation of intravascular ultrasound images and the accuracy of ultrasound measurements of vascular geometry. METHODS: Intravascular ultrasound images were obtained with a mechanically rotated catheter-tip transducer and recorded on videotape. Initial validation studies were performed in fresh, post-mortem arterial specimens, which were filled with saline at physiological pressures. Ultrasound images at specific sites were compared with the pathological findings at that site and measurements of luminal diameter were compared with corresponding angiographic measurements. Subsequently, intravascular ultrasound was employed to examine the aorta, ilio-femoral and coronary arteries in patients undergoing balloon angioplasty. RESULTS: The pathological correlations showed that intravascular ultrasound can detect early initial thickening and mild atherosclerotic lesions that do not result in luminal deformation. Ultrasound images provided definition of calcified, fibrotic and lipid-filled lesions. Ultrasound measurements of luminal diameter correlated well with pathology measurements (r = 0.93), as did ultrasound measurements of plaque area (r = 0.89). The in vivo studies demonstrated that intravascular ultrasound can define atheroma lesions not evident on contrast angiography and permits detailed evaluation of the results of interventions such as balloon angioplasty. CONCLUSIONS: Intravascular ultrasound provides a unique window upon arterial structure and pathology in humans. Ultrasound images allow accurate measurements of vascular geometry and define early atheromatous lesions that are not evident with angiography.

Arteries↗

PubMed1993

Transluminal placement of a prosthetic graft-stent device for treatment of subclavian artery aneurysm.

A 78-year-old man was seen with an expanding 5 cm false aneurysm of the right subclavian artery. This was treated by an intraluminal graft-stent device introduced through the brachial artery via a 16 F sheath. The graft was constructed from two polytetrafluoroethylene patches of 0.4 mm thickness and anchored in the subclavian artery by an 8 mm stainless steel stent. The procedure was monitored by an image intensifier. Completion arteriography and postoperative duplex scanning confirmed normal flow through the subclavian artery with no communication between the lumen and the aneurysmal sac. The patient recovered without complication.

Aged↗

PubMed1992

Characterization and expression of U1snRNA genes from potato.

U1 small nuclear RNAs (U1snRNAs) occur in the nucleus of plants and animals where, complexed with several proteins in the form of U1 small nuclear ribonucleoprotein particles (U1snRNPs), they play an important role in precursor messenger RNA (pre-mRNA) splicing. Ten potato U1snRNA genes have been isolated on two genomic clones illustrating the clustering of this multigene family on the potato genome. Based on both the sequence of their coding regions and upstream regulatory elements, seven of the genes are potentially functional. The other three genes were pseudogenes with defective promoter or coding region sequences. Analysis of expression of individual cloned U1snRNA genes in transfected tobacco protoplasts was impossible due to the similarity of U1snRNA sequences in tobacco. However, by marking the coding regions with oligonucleotides or constructing chimaeric genes consisting of a potato U1snRNA promoter region and maize U5snRNA coding region, three of the U1 promoter regions were shown to be transcriptionally active.

Base Sequence↗