PubMed Health⌕ Search

Biomedical subjects

R Waugh

Publications and source records attributed to R Waugh.

At least 73 records · Page 4Linked to original sources
PubMed1997

Percutaneous microcoil embolization of intraperitoneal intrahepatic and extrahepatic biliary fistulas.

BACKGROUND: Persistent intraperitoneal biliary fistulas are associated with significant morbidity and mortality. Percutaneous drainage, stenting, and endoscopic sphincterotomy or embolization of biliary radicals have largely replaced the need for hepatic resection or biliary reconstruction in managing such fistulas. When endoscopy is contraindicated, a previously undescribed technique of percutaneous embolization of intrahepatic and extrahepatic biliary fistula following penetrating liver trauma, and orthotopic liver transplant and its application in three patients, will be discussed. METHODS: Embolization procedures were performed by an interventional radiologist. Percutaneous trans-hepatic cholangiography via a standard right-side approach or via tube cholangiography was initially performed and the fistula defined. Coaxial catheter systems were used (5 Fr angiography catheters and Tracker 18 infusion catheters), and were positioned within the biliary tree as close as possible to the origin of the fistula. Embolization was performed using vascular Embolization 28 coils (WA Cook) 2-3 mm x 2 cm coils, straight Hilal 18 embolization coils (WA Cook) 5-7 cm, as well as Gelfoam (Upjohn) 1 mm pellets, and Histoacryl (B. Braun) 0.25-1 mL. Occlusion of the duct was confirmed by a selective intrahepatic cholangiogram. In cases of multiple fistulas several embolizations were performed at subsequent procedures. Follow-up is over 13 months without adverse event. RESULTS: The technique was used in the three cases and was successful in all. A peripheral biliary fistula required embolization twice and two cystic leaks were cured after a single attempt. CONCLUSIONS: Percutaneous embolization of biliary fistulas provides a management option in cases where conservative treatment has failed and other techniques are relatively contraindicated. The technique is effective and safe in skilled hands, and avoids major surgery. The long-term effect of microcoils in the biliary tree is unknown.

Adult↗
PubMed1997

Discriminating between barley genotypes using microsatellite markers.

Eleven microsatellite loci were used to survey 24 barley genotypes representing 23 cultivars and a breeding line in official trials. Three separate combinations of four microsatellites had overall probabilities of identity of less than 1 in 1000 and could distinguish between all 24 barley genotypes. It is shown that the microsatellites could distinguish genotypes with the same pedigree and also that patterns of discrimination were different from those obtained from botanical descriptors. The stability of microsatellites across different generations was demonstrated by a retrospective analysis of the pedigree of Golden Promise. One of the parents of Maythorpe, the immediate ancestor of Golden Promise, was shown to be Irish Goldthorpe rather than Goldthorpe, thereby resolving conflicting published pedigrees.

DNA, Plant↗
PubMed1997

Three-year experience with the White-Yu Endovascular GAD Graft for transluminal repair of aortic and iliac aneurysms.

PURPOSE: To report a > 3-year experience with a modular, balloon-expandable endovascular graft used for aneurysm exclusion in the aorta and other arteries. METHODS: The customized White-Yu Endovascular GAD Graft, a woven polyester prosthesis with an intrinsic Elgiloy wire graft attachment system along the body of the graft, is a flexible endograft design available in straight, tapered, and bifurcated versions that can be delivered transluminally through 18F to 24F sheaths. RESULTS: Since July 1993, 93 patients have received the White-Yu endograft for treatment of 76 abdominal aortic, 3 thoracic aortic, 13 iliac, and 1 popliteal aneurysms. Of the 79 aortic procedures, 39 involved straight tube grafts, 20 were tapered aortoiliac models, and 20 were bifurcated devices. Success rates for tube grafts were 81% in the abdominal aorta and 100% for the thoracic aorta; 5 primary endoleaks (14%) and 2 conversions to surgery (5.6%) occurred with this graft type. Aortoiliac grafts were deployed successfully in 95% (19/20) of cases with 1 conversion (5%) due to thrombosis. Seventy-five percent of the bifurcated endograft procedures were successful, with 4 conversions (20%) for technical failures and 1 graft thrombosis. Four additional endografts were deployed to treat two primary and two secondary endoleaks in tube graft patients. Two access-related arterial injuries were treated surgically. There was one case of embolus to the distal femoral artery but no microembolization. Overall perioperative (30-day) mortality was 3.1%. Over a mean 18-month follow-up (range 2 to 39), no late graft thrombosis, stenosis, or graft migration has been seen on CT scans or X ray. Endoleak has not been detected in any aortoiliac or bifurcated graft. Aneurysm size has diminished consistently in successfully treated cases. CONCLUSIONS: The White-Yu endograft appears to offer a safe, efficacious, and minimally invasive means of excluding aneurysms from the circulation. Improvements in patient selection, surgical techniques, and equipment have reduced the incidence of endoleak and conversion to open repair over the course of the evaluation.

Aortic Dissection↗
PubMed1997

Endoluminal repair of abdominal aortic aneurysms: strengths and weaknesses of various prostheses observed in a 4.5-year experience.

PURPOSE: To summarize the results of endovascular abdominal aortic aneurysm (AAA) treatment using several endograft designs over a 4.5-year experience and offer comparisons on the various devices. METHODS: From May 1992 to August 1996, 121 AAA patients meeting the criteria for an endoluminal repair were treated with 1 of 5 endograft designs in three configurations. The endografts were implanted in the operating room under fluoroscopic control. Follow-up included contrast-enhanced computed tomography within 10 days of operation, 6 months postoperatively, and annually thereafter. RESULTS: Endografts were successfully deployed in 106 patients (88%). Fifteen cases were converted to open repair. Six procedure-related deaths occurred within 30 days owing to myocardial infarction (3), combined renal failure and septicemia (2), and multisystem failure (1). There were 36 local/vascular complications (30%) and 18 systemic/remote complications (15%). Of the 121 patients undergoing endoluminal AAA repair, 93 (77%) are currently alive and well with their AAAs excluded from the circulation. CONCLUSIONS: Trends in endoluminal AAA repair and prosthetic design point toward simpler devices and earlier treatment of smaller aneurysms once the long-term outcome of aortic endografting has been determined.

Aortic Aneurysm, Abdominal↗
PubMed1997

The Ty1-copia group of retrotransposons in plants: genomic organisation, evolution, and use as molecular markers.

The genomic organisation and diversity of the Ty1-copia group retrotransposons has been investigated in several crop plants and their relatives from both dicotyledonous and monocotyledonous families, including potato (Solanum tuberosum), faba beans (Vicia faba), Vicia melanops, Vicia sativa, barley (Hordeum vulgare), rye (Secale cereale), and onion (Allium cepa). Extreme heterogeneity in the sequence of the Ty1-copia retrotransposons from all these plants was revealed following sequence analysis of reverse transcriptase fragments. The estimated copy numbers of the Ty1-copia group retrotransposons for the genomes of S. tuberosum, L. esculentum, A. cepa, S. cereale, and V. faba is highly variable, ranging from a few hundred to approximately a million copies per genome. In situ hybridisation data from metaphase and prophase chromosomes of V. faba, S. cereale, and H. vulgare suggest that retrotransposon sequences are dispersed throughout the euchromatic regions of the genome but are almost undetectable in most heterochromatic regions. In contrast, similar data from metaphase chromosomes of A. cepa suggests that although retrotransposon sequences are dispersed throughout the euchromatic regions of the genome, they are predominantly concentrated in the terminal heterochromatin. These results are discussed in the context of the role played by the Ty1-copia group retrotransposons in the evolution of the plant genome. Lastly, the application of retrotransposon sequences as genetic markers for mapping genomes and for studying genetic biodiversity in plants is presented.

Chromosome Mapping↗
PubMed1996

Repair of abdominal aortic aneurysms by the endoluminal method: outcome in the first 100 patients.

OBJECTIVE: To report the outcome in our first 100 patients with abdominal aortic aneurysms repaired by the endoluminal method. DESIGN: Analysis of concurrently collected data of patients undergoing repair of an aortic aneurysm. The technique involves the delivery of an endograft into the abdominal aorta by means of a sheath inserted through the femoral or iliac artery. Clinical examination and contrast-enhanced computed tomography (CT) were performed within 10 days, at six months and then annually after operation. SETTING: Royal Prince Alfred Hospital, Sydney, a tertiary referral teaching hospital. PATIENTS: 100 patients, seven women and 93 men, with a mean age of 70 years (range, 46-87), treated between May 1992 and December 1995. Because of comorbidities, 43 of the patients had been considered unsuitable for conventional open repair at other medical centres. Our criteria for inclusion were the presence of a 1.5-cm or greater segment of thrombus-free aorta between the lowermost renal artery and the commencement of the aneurysm, and iliac arteries allowing access to the aorta from the groin. OUTCOME MEASURES: (i) Need to convert to open repair; (ii) damage to the arteries from sheath insertion; (iii) communication between the aneurysmal sac and the circulation; (iv) death within 30 days; (v) effect on aneurysmal diameter. RESULTS: Endografts were successfully deployed in 88 patients. In the remaining 12 patients endoluminal repair was converted to open repair. There were five deaths within 30 days of the operation, including three in the failed group. Damage to the femoral or iliac arteries from sheath insertion occurred in five patients. These were repaired without the need to convert to open repair. No patients were lost to follow-up (62 patients have been followed up for at least six months). Contrast-enhanced computed tomography shows progressive diminution in maximal transverse diameter of the aneurysms with time, after successful exclusion of the aneurysmal sac from the general circulation. CONCLUSION: Endoluminal repair of abdominal aortic aneurysms is feasible and this method of repair is durable in mid-term follow-up.

Aged↗
PubMed1996

DNA fingerprints of rice (Oryza sativa) obtained from hypervariable chloroplast simple sequence repeats.

The aim of this research was to develop a convenient polymerase chain reaction-based assay that would allow intraspecific chloroplast variability to be detected. Our approach is based on the detection of length polymorphism within chloroplast mononucleotide microsatellite loci. Information from the fully sequenced rice chloroplast genome was used to identify 12 regions with a minimum of ten uninterrupted mononucleotide repeats. Primers flanking these repeats were used in conjunction with polymerase chain reaction to examine levels of polymorphism in six wild and 14 cultivated rice accessions. A total of six of the primer pairs revealed length polymorphism with between two and five size variants being detected. Diversity indices varied between 0.07 and 0.72. The length variation detected at multiple, physically linked sites was used to identify 15 unique haplotypes with an overall diversity index of 0.90. This level of polymorphism is sufficiently high to allow chloroplast variability to be studied at the intraspecific level. An additional 47 Oryza sativa accessions were also assayed with 31 unique chloroplast haplotypes being detected. The distribution of these haplotypes is described in relation to isozyme groupings and subspecies differentiation. The relevance and implications of these results for plant population genetics and the management of germplasm collections is discussed.

Chloroplasts↗
PubMed1996

Exon skipping induced by cold stress in a potato invertase gene transcript.

We show that two invertase genes in potato, like most other plant invertase genes, include a very short second exon of 9 bp which encodes the central three amino acids of a motif highly conserved in invertases of diverse origin. This mini-exon is one of the smallest known in plants and pre-mRNA from these genes may be susceptible to alternative splicing, because of a potential requirement for specialized interaction with the splicing machinery to ensure correct processing for the production of a mature mRNA. No evidence of aberrant post-transcriptional processing was observed during normal invertase gene expression in potato. The fidelity of post-transcriptional processing of the pre-mRNA from one of the genes was perturbed by cold stress, resulting in the deletion of the mini-exon from some transcripts. This alternative splicing event occurred under cold stress in both leaf and stem, but was not induced by wounding. This adds an example of exon skipping and the induction of alternative processing by cold stress to the small number of transcripts which have been shown to exhibit alternative splicing in plants. The differential sensitivity of post-transcriptional processing to cold stress observed for the two transcripts examined will permit further dissection of the nucleotide sequence requirements for their accurate splicing.

Alternative Splicing↗
PubMed1996

A prospective study of anatomico-pathological changes in abdominal aortic aneurysms following endoluminal repair: is the aneurysmal process reversed?

AIM: The aim of this prospective study was to analyse early anatomico-pathological changes in abdominal aortic aneurysms (AAA) following endoluminal repair to determine if the natural history of continued expansion of AAA is reversed. MATERIALS AND METHODS: Sixty-seven of 85 patients undergoing endoluminal AAA repair between May 1992 and August 1995 had their operations prior to the end of February 1995 and were potentially available for follow up at 6 months or longer after operation. Excluded were: patients with failed endoluminal repairs (n = 14), patients who died within 6 months of operation (n = 5), patients with anastomotic AAA (n = 1), leaving 47 patients in the study group. Based on contrast enhanced CT performed preoperatively, within 10 days of operation and 6, 12 and 18 months after operation patients were divided into two groups: those in whom the AAA maximum transverse diameter (MTD) decreased Group I (n = 39) and those in which it increased Group II (n = 8). The following parameters were analysed: diameter of the supra coeliac aorta, MTD and the dimensions of the proximal and distal necks of the AAA plus extravasation ("leak") of contrast into the aneurysmal sac. RESULTS: Leak of contrast was seen in 0 of 39 patients in Gp I and 5 of 8 patients in Gp II. Patients in Group I experienced a progressive diminution in AAA mean MTD. The diameters of the proximal and distal necks increased but there was no shortening of the length of the necks in this group. In Group II the AAA MTD was dependent on whether or not the aneurysmal sac was isolated from the circulation. The diameter of the proximal and distal necks increased irrespective of this fact. CONCLUSION: We conclude that in early follow up AAA which diminish in diameter following endoluminal repair remain isolated from the general circulation. Co-incident with this decrease in AAA diameter, the proximal and distal necks increase in diameter but do not undergo any shortening in length. This paradoxical increase in neck diameter, was not progressive in the period of follow-up.

Aged↗
PubMed1996

Detection and pattern of interspecific hybridization between Gliricida sepium and G. maculata in Meso-America revealed by PCR-based assays.

Gliricidia sepium provides a variety of products important for rural communities in tropical countries. Native populations in Meso-America currently form an important source of seed for distribution to farmers, but concerns centre on mechanisms which may lead to their genetic erosion, including anthropogenic dispersal and subsequent introgression from the related species, G. maculata. Populations of Gliricidia were examined genetically using approaches based on the polymerase chain reaction to test for interspecific hybridization and introgression between G. sepium and G. maculata. Analysis involved 13 RAPD and two RFLP-PCR markers which were identified to have species-diagnostic distributions. Data from both approaches corresponded and indicated three locations where multilocus genotypes were consistent with an hybrid origin. Data at one of these sites was consistent with introgression following hybridization. The hybrid origin of populations was supported by the intermediate geographical location of these sites to 'pure' populations of each species. Analysis of maternally inherited organellar DNA, which involved the detection of SSCPs in mitochondrial DNA amplification products, allowed further delineation of genetic structure among Gliricidia populations. Mitochondrial data indicated a high degree of organelle differentiation between sampled locations and identified G. sepium- and G. maculata-diagnostic haplotypes. This data supported the interpretation of genetic structure based on RAPDs and RFLP-PCR. In addition, cytonuclear analysis allowed the directionality of gene transfer during the formation of hybrid populations to be described. Despite evidence for the occurrence of interspecific hybridization and introgression in Gliricidia, important resource populations of G. sepium on the Pacific coast appear to have retained their genetic integrity. Implications in terms of the conservation and utilization of genetic resources within the genus are discussed.

Base Sequence↗
PubMed1995

Polymerase chain reaction-based assays for the characterisation of plant genetic resources.

Plant genetic resources are an important component of biodiversity and provide the basic genetic variability that allow new and improved cultivars to be developed. Numerous germplasm collections have been established and it is important to established that such collections are representative and accessible to breeders and biotechnologists. Molecular markers provide the best estimate of genetic diversity since they are independent of the confounding effects of environmental factors. Assays based on the polymerase chain reaction (PCR) are considered to meet both the technical and genetical requirements for the characterisation of plant and animal genetic resources. Two main approaches are described, based on anonymous and defined primers. The use of both randomly amplified polymorphic DNA (RAPD) and microsatellites or simple sequence repeats (SSR) for the characterisation of perennial tree species, and distribution of variability within gene pools is reported. The detection of interspecific gene introgression between coffee species with RAPD markers is described together with the use of microsatellites to genotype potato. The use of PCR-based assays will facilitate the evaluation and utilisation of plant genetic resources.

Base Sequence↗
PubMed1995

Fulminant hepatic failure post liver transplantation: clinical syndromes, correlations and outcomes.

This paper reports the clinical syndrome of fulminant hepatic failure (FHF) following liver transplantation. FHF was defined as the sudden onset of liver failure [encephalopathy and prolonged International Normalised Ratio (INR)] without arterial thrombosis in the setting of a liver allograft. FHf post-transplant was seen in 8/154 (5.2%) adult patients undergoing transplantation. These eight patients developed a clinical syndrome characterised by: (a) a rapid rise in ALT levels to above 1000 U/l (mean maximum 1600 U/l), (b) a sudden increase in the INR to above 5 (mean maximum 5.6), (c) the development of high fever, (d) the persistence of thrombocytopenia (mean nadir 40 x 10(9)/dl), (e) a progressive rise in the bilirubin (mean maximum 400 mumol/l) and (f) the development of hepatic encephalopathy. In seven cases this syndrome occurred following good initial graft function at day 6 post (mean)-transplant. In one case the above syndrome developed immediately after liver transplantation. Four of the eight patients developed multiorgan failure associated with systemic acidosis (mean pH 6.84). All of these patients died (mean day 11). Four patients developed systemic alkalosis. Two of these four patients underwent successful retransplantation (on days 12 and 13) and remain alive at a mean of 11 months post-transplant. Six of the eight patients received OKT3 therapy without any apparent affect on clinical outcome. Compared to control group of patients (n = 28), 8 versus 2/28 had a positive cross-match with donor lymphocytes (P = NS), 1/8 versus 7/28 were ABO-non-identical (P = NS), 3/8 versus 10/21 had total MHC mismatches (P = NS) and 5/7 versus 6/16 had UW ischemic times above 10 h (P = NS). No patients had main hepatic artery thrombosis on angiography although four patients had evidence of intrahepatic microthrombi or arterial necrosis at autopsy. In all cases the histology showed massive haemorrhagic necrosis. Three cases had evidence of veno-occlusive lesions whilst foam cell arteriopathy was seen in two cases. Immunofluorescence was performed in three cases. In two cases there was evidence of immunoglobulin, complement and fibrin deposition in blood vessels. In conclusion, we describe an uncommon clinical syndrome occurring post liver transplant. This syndrome represents humorally mediated allograft rejection but there seems to be no relationship with tissue matching (antibody, ABO, MHC) or donor ischaemic times. If recognised earlier in the absence of multiorgan failure, urgent retransplantation seems to be the only effective therapy.

Acidosis↗
PubMed1995

Induction chemotherapy via hepatic artery for gallbladder carcinoma.

The prognosis after surgery for carcinoma of the gallbladder remains poor. Treatment failure is frequently due to loco-regional recurrence in the adjacent liver and regional lymph nodes. We report a case of gallbladder carcinoma with proven involvement of the cystic duct node (Nevin stage IV). Pre-operative intra-arterial induction chemotherapy using two cycles of cisplatin, 5-fluorouracil, doxorubicin and mitomycin C was administered via the common hepatic artery. A radical cholecystectomy was performed 4 weeks later, and histological examination of the resected specimen showed a near total response, with no residual nodal disease. The patient remains well and free of disease 3 years later. Intra-arterial induction chemotherapy warrants further evaluation.

Adenocarcinoma↗
PubMed1995

Diversity and genetic differentiation among subpopulations of Gliricidia sepium revealed by PCR-based assays.

Randomly amplified polymorphic DNA (RAPD), and a mitochondrial marker based on amplification of the V7 region of the mitochondrial small ribosomal RNA (srRNA) gene, were used to partition genetic variation within a single population of Gliricidia sepium sampled from Guatemala. Seventeen per cent of the variation detected with RAPDs was partitioned among subpopulations and indicated a greater level of discrimination than previously detected with isozymes. Cluster analysis indicated a direct relationship between this variation and the geographical distance between subpopulations. A polymorphism identified within the maternally inherited mitochondrial V7 srRNA product, which relied on digestion with restriction endonucleases, confirmed the genetic subdivision identified with RAPDs, and suggested a relatively limited role for seed in gene dispersal.

Base Sequence↗
PubMed1995

Detection of genetic diversity in tea (Camellia sinensis) using RAPD markers.

Camellia sinensis is a beverage tree crop native to Southeast Asia and introductions have been made into several nonindigenous countries. No systematic assessment of genetic variability in tea has been done anywhere. In this study, random amplified polymorphic DNA (RAPD) analysis was used to estimate genetic diversity and taxonomic relationships in 38 clones belonging to the three tea varieties, assamica, sinensis, and assamica ssp. lasiocalyx. Extensive genetic variability was detected between species, which was partitioned into between and within population components. Seventy percent of the variation was detected within populations. Analyses based on band sharing separated the three populations in a manner consistent with both the present taxonomy of tea and with the known pedigrees of some clones. RAPD analysis also discriminated all of the 38 commercial clones, even those which cannot be distinguished on the basis of morphological and phenotypic traits.

Base Sequence↗
PubMed1995

Do exercise and weight loss reduce blood pressure in patients with mild hypertension?

We conclude from our review that exercise and weight loss offer some promise as non-pharmacologic treatments for hypertension. Unfortunately, most available studies are methodologically unsound, and the mechanisms by which exercise lowers blood pressure are not known. The use of randomized controlled designs, precise and comprehensive measurements of blood pressure and fitness, and clearly described interventions will be necessary if we are to decide whether exercise and diet lower blood pressure in patients with hypertension. We are now about to embark on such a study (see sidebar) in hopes that it will provide a clear answer to the question of whether these non-pharmacologic treatments can help the large numbers of Americans (and North Carolinians) with high blood pressure.

Exercise↗