Biomedical subjects

R Waugh

Publications and source records attributed to R Waugh.

At least 19 recordsLinked to original sources

PubMed2000

Exercise and weight loss reduce blood pressure in men and women with mild hypertension: effects on cardiovascular, metabolic, and hemodynamic functioning.

BACKGROUND: Lifestyle modifications have been recommended as the initial treatment strategy for lowering high blood pressure (BP). However, evidence for the efficacy of exercise and weight loss in the management of high BP remains controversial. METHODS: One hundred thirty-three sedentary, overweight men and women with unmedicated high normal BP or stage 1 to 2 hypertension were randomly assigned to aerobic exercise only; a behavioral weight management program, including exercise; or a waiting list control group. Before and following treatment, systolic and diastolic BPs were measured in the clinic, during daily life, and during exercise and mental stress testing. Hemodynamic measures and metabolic functioning also were assessed. RESULTS: Although participants in both active treatment groups exhibited significant reductions in BP relative to controls, those in the weight management group generally had larger reductions. Weight management was associated with a 7-mm Hg systolic and a 5-mm Hg diastolic clinic BP reduction, compared with a 4-mm Hg systolic and diastolic BP reduction associated with aerobic exercise; the BP for controls did not change. Participants in both treatment groups also displayed reduced peripheral resistance and increased cardiac output compared with controls, with the greatest reductions in peripheral resistance in those in the weight management group. Weight management participants also exhibited significantly lower fasting and postprandial glucose and insulin levels than participants in the other groups. CONCLUSIONS: Although exercise alone was effective in reducing BP, the addition of a behavioral weight loss program enhanced this effect. Aerobic exercise combined with weight loss is recommended for the management of elevated BP in sedentary, overweight individuals.

Adult↗

PubMed2000

UK CropNet: a collection of databases and bioinformatics resources for crop plant genomics.

The UK Crop Plant Bioinformatics Network (UK CropNet) was established in 1996 in order to harness the extensive work in genome mapping in crop plants in the UK. Since this date we have published five databases from our central UK CropNet WWW site (http://synteny.nott.ac.uk/) with a further three to follow shortly. Our resource facilitates the identification and manipulation of agronomically important genes by laying a foundation for comparative analysis among crop plants and model species. In addition, we have developed a number of software tools that facilitate the visualisation and analysis of our data. Many of our tools are made freely available for use with both crop plant data and with data from other species.

Crops, Agricultural↗

PubMed2000

Life-table analysis of primary and assisted success following endoluminal repair of abdominal aortic aneurysms: the role of supplementary endovascular intervention in improving outcome.

AIM: the aim of this study was to analyse the effect of supplementary endovascular intervention on the outcome of primary endoluminal repair of abdominal aortic aneurysm (AAA). METHODS: between May 1992 and December 1998, 266 patients underwent endoluminal repair of AAA. Minimum period of follow-up was 6 months. Those patients in whom the endoprosthesis could not be deployed were converted to open repair at the primary operation. Patients developing an early endoleak, within 31 days, were treated by a period of observation and secondary endovascular intervention in persistent cases. Patients developing a late endoleak were treated similarly, without a period of observation. Outcome was analysed by the life-table method. Primary success was defined as exclusion of the aneurysm from the circulation resulting from the original operation. Assisted success occurred when aneurysms with endoleaks became excluded from the circulation as a result of supplementary endovascular intervention. RESULTS: endoluminal repair failed in 17 patients requiring conversion to open repair at the original operation. Supplementary endovascular intervention was undertaken in 26 patients, with early endoleaks (n=6) and late endoleaks (n=20). Interventions involved deployment of secondary endoluminal grafts within the primary grafts (n=22), and coil embolisation (n=4). Successful exclusion of the aneurysm sac was achieved in 22 of 26 (85%) patients undergoing supplementary endovascular procedures. Conditional cumulative incidence of primary graft failure and secondary graft failure in the presence of all-cause mortality at 6 years was 47% and 25% respectively. CONCLUSIONS: supplementary endovascular intervention is an important adjunct to endoluminal AAA repair with the potential to improve outcome and avoid conversion to open repair. Successful supplementary endovascular intervention was achieved in 85% of patients in whom it was attempted. Life-table analysis showed these supplementary procedures to be durable in the long term.

Aged↗

PubMed2000

Comparison of first- and second-generation prostheses for endoluminal repair of abdominal aortic aneurysms: a 6-year study with life table analysis.

PURPOSE: The outcome of endoluminal repair of abdominal aortic aneurysms with two generations of prostheses was analyzed and compared. METHODS: Between May 1992 and December 1998, 266 patients underwent elective endoluminal repair of an AAA. First-generation prostheses were used in 118 patients (group I), and second-generation prostheses were used in 148 patients (group II). The two groups were similar in age, sex, and size of AAA. The proportion of patients with comorbidities was higher in group I than in group II, but not significantly. First-generation devices were characterized by large (24F internal diameter) delivery systems, one-piece construction, and a lack of metallic support throughout their length. Second-generation devices had smaller (21F or smaller internal diameter) delivery systems, modular construction, and a metallic frame throughout the length of the prostheses. The major end-point criteria were survival and successful endoluminal repair. Success was defined as the exclusion of the aneurysm sac from the circulation, with stability or the reduction in AAA maximum transverse diameter. Persistent endoleaks were classified as failures, irrespective of whether they were subsequently corrected by means of secondary endovascular intervention. The minimum follow-up period was 5 months for each of the 266 patients. Analysis was performed by means of the life-table method. RESULTS: Perioperative mortality was not significantly different between group I (4.2%) and group II (2.7%). There was a statistically significant difference between the survival curves of the two generations, which favored group II (P =.012). There was a significant (P <.001) difference between the two generations of patients in their conditional probability of graft failure when the competing risk of all-cause mortality was considered. Second-generation patients were at a lower risk of graft failure than first-generation patients. The probability of failure, expressed as a proportion of grafts failing at 2 years, was 0.15 for patients with second-generation prostheses and 0.33 for patients with first-generation prostheses. CONCLUSION: Endoluminal AAA repair is a safe procedure, whether first- or second-generation prostheses are used. Survival and probability of graft success were significantly higher with second-generation prostheses than with first-generation prostheses. This improvement in outcome resulted from a combination of increasing clinical experience and advances in technology. A more accurate evaluation of the role of the endoluminal method in AAA repair would be achieved by studying patients in whom second-generation devices were used, rather than longer term studies in which first- and second-generation devices were used.

Aged↗

PubMed2000

Effects of exercise and weight loss on mental stress-induced cardiovascular responses in individuals with high blood pressure.

The purpose of this study was to determine the effects of exercise and weight loss on cardiovascular responses during mental stress in mildly to moderately overweight patients with elevated blood pressure. Ninety-nine men and women with high normal or unmedicated stage 1 to stage 2 hypertension (systolic blood pressure 130 to 179 mm Hg, diastolic blood pressure 85 to 109 mm Hg) underwent a battery of mental stress tests, including simulated public speaking, anger recall interview, mirror trace, and cold pressor, before and after a 6-month treatment program. Subjects were randomly assigned to 1 of 3 treatments: (1) aerobic exercise, (2) weight management combining aerobic exercise with a behavioral weight loss program, or (3) waiting list control group. After 6 months, compared with control subjects, participants in both active treatment groups had lower levels of systolic blood pressure, diastolic blood pressure, total peripheral resistance, and heart rate at rest and during mental stress. Compared with subjects in the control group, subjects in the exercise and weight management groups also had greater resting stroke volume and cardiac output. Diastolic blood pressure was lower for the weight management group than for the exercise-only group during all mental stress tasks. These results demonstrate that exercise, particularly when combined with a weight loss program, can lower both resting and stress-induced blood pressure levels and produce a favorable hemodynamic pattern resembling that targeted for antihypertensive therapy.

Adult↗

PubMed1999

Effects of exercise training on older patients with major depression.

BACKGROUND: Previous observational and interventional studies have suggested that regular physical exercise may be associated with reduced symptoms of depression. However, the extent to which exercise training may reduce depressive symptoms in older patients with major depressive disorder (MDD) has not been systematically evaluated. OBJECTIVE: To assess the effectiveness of an aerobic exercise program compared with standard medication (ie, antidepressants) for treatment of MDD in older patients, we conducted a 16-week randomized controlled trial. METHODS: One hundred fifty-six men and women with MDD (age, > or = 50 years) were assigned randomly to a program of aerobic exercise, antidepressants (sertraline hydrochloride), or combined exercise and medication. Subjects underwent comprehensive evaluations of depression, including the presence and severity of MDD using Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria and Hamilton Rating Scale for Depression (HAM-D) and Beck Depression Inventory (BDI) scores before and after treatment. Secondary outcome measures included aerobic capacity, life satisfaction, self-esteem, anxiety, and dysfunctional cognitions. RESULTS: After 16 weeks of treatment, the groups did not differ statistically on HAM-D or BDI scores (P = .67); adjustment for baseline levels of depression yielded an essentially identical result. Growth curve models revealed that all groups exhibited statistically and clinically significant reductions on HAM-D and BDI scores. However, patients receiving medication alone exhibited the fastest initial response; among patients receiving combination therapy, those with less severe depressive symptoms initially showed a more rapid response than those with initially more severe depressive symptoms. CONCLUSIONS: An exercise training program may be considered an alternative to antidepressants for treatment of depression in older persons. Although antidepressants may facilitate a more rapid initial therapeutic response than exercise, after 16 weeks of treatment exercise was equally effective in reducing depression among patients with MDD.

Aged↗

PubMed1999

Adverse events after endoluminal repair of abdominal aortic aneurysms: a comparison during two successive periods of time.

PURPOSE: The aim of this study was to document the incidence rate of adverse events after endoluminal repair of abdominal aortic aneurysms (AAAs) during two successive periods of time. METHODS: One hundred ninety patients (175 men, 15 women; mean age, 72 years) underwent endoluminal repair of AAAs in a 5(1/2)-year period. Adverse events were documented prospectively for all the patients throughout this interval. An adverse event was defined as any of the following events: a death within 30 days, a conversion to open repair, the need for further intervention (either open or endovascular), the need for hemodialysis, a failure to cure the AAA, and wound complications. The patients were divided into two groups those who underwent operation in the initial 3-year period (group I; n = 75) and those who underwent operation in the subsequent 2(1/2)-year period (group II; n = 115). The results were analyzed for total adverse events for both periods of time and for difference in incidence rates within categories of adverse events between the two groups. RESULTS: Eight patients (4.2%) died in the perioperative period. The endoluminal repair failed in 17 patients (8.9%), which necessitated a primary conversion to open repair at the original operation. In 88 patients, 110 adverse events occurred. There was no significant difference in the incidence rates of adverse events in patients in group I (37/75) and group II (51/115). Apart from primary conversion (P =.007), there was no significant difference in the incidence rates of adverse events between group I and group II within the following categories: perioperative (within 30 days) deaths, primary conversion, secondary conversion, supplementary endoluminal repair, intervention for lower limb ischemia, hemodialysis necessitated, failure to cure the AAA as a result of persistent endoleak, and wound complications. CONCLUSION: Despite improvements in technology and increasing experience, adverse events continue to occur in a relatively high proportion of patients (45%) who undergo endoluminal repair of AAA. Reporting the incidence rates of adverse events provides a more accurate picture of the morbidity rates of the endoluminal method rather than simply listing the procedures as successes or failures. The similarity in the incidence rates of adverse events in patients in group I and group II suggests that there are inherent risks in the endoluminal method rather than iatrogenic complications that occur during the learning curve with a new technique.

Aged↗

PubMed1999

Endovascular treatment of abdominal aortic aneurysms.

OBJECTIVE: The purpose of this paper is to briefly review the historical aspects and outcome of endoluminal abdominal aortic aneurysm (AAA) repair and summarise two studies presented at the 1997 and 1998 meetings of the Society for Vascular Surgery. PATIENTS: Between May 1992 and September 1998 the endoluminal method was used to repair arterial aneurysms in 304 patients at the Royal Prince Alfred Hospital, Sydney, a tertiary referral teaching hospital. The study focuses on 243 patients with true AAA who underwent primary repair. There were 17 females and 226 males with a mean age of 72 years. Co-morbidities leading to rejection for conventional open repair were present in 83 patients. The criteria for inclusion included a segment of thrombus-free aorta between the lowermost renal artery and the commencement of the aneurysm of 1.5 cm or greater and iliac arteries that allowed access to the aorta from the groin. The technique involved the delivery of an endograft into the abdominal aorta by means of a sheath inserted through the femoral or iliac artery. Laparotomy associated with conventional open repair was avoided. Outcome measures included clinical examination and contrast-enhanced computed tomography (CT) within 10 days, at 6, 12, 18 months after operation and then annually thereafter. RESULTS: Endografts were successfully deployed in 226 patients. In the remaining 17 patients endoluminal repair was converted to open repair. There were 8 deaths within 30 days of operation giving a perioperative mortality rate of 3.3%. The two studies presented to the Society for Vascular Surgery concern: (i) a concurrent comparison of the endoluminal versus open methods of treating AAA; and (ii) a comparison of adverse events following endoluminal repair of AAA during two consecutive periods of time.

Aged↗

PubMed1999

An active liver transplant programme for hepatocellular carcinoma in cirrhotic patients: is it justified?

Even at an early stage, hepatocellular carcinoma (HCC) in patients with cirrhosis is often deemed unresectable because of limited liver reserve. In these circumstances, liver transplantation (LTx) offers some hope for palliation or cure. The results of LTx for selected cirrhotic patients with HCC were analysed. The outcomes were compared with those of patients who underwent LTx for other forms of hepatic malignancy and those who underwent LTx for non-malignant conditions. Four hundred and eighty LTx were performed in 441 patients between January 1986 and December 1998. Twenty-eight LTx recipients (25 males, 3 females) of mean age 51 (14 63) yr had cirrhosis and HCC. Twenty-seven patients had underlying predisposing conditions (11 had hepatitis B, 10 had hepatitis C, 2 had hepatitis B and C, 1 had haemochromatosis, 1 had autoimmune hepatitis, 1 had alcoholic cirrhosis and 1 had alpha-1 antitrypsin deficiency). In 22 patients, HCC was diagnosed pre-LTx, and in 6 patients, the cancers were discovered incidentally. The average tumour size and number were 2.8 (0.4-11.5) cm and 1.3 (1-4), respectively. Two patients with known HCC died during and shortly after the LTx operation. Of the other patients, 3 died; 1 died of HCC recurrence 18 months post-LTx, 1 died of graft failure from recurrent hepatitis C and 1 died of fungal sepsis. Twenty-three (82%) patients survived to 22.5 (0.5-96) months post-LTx without HCC recurrence and with 1- and 3-yr actuarial patient survival rates of 87 and 76%, respectively. Equivalent survival rates of patients who underwent LTx for other malignancies (n = 11) were 82 and 46% (p = NS), and for those who underwent LTx for benign causes (n = 402), they were 77 and 73% (p = NS). All 15 patients with known HCC, who met the selection criteria now in use, survived. LTx can result in prolonged. cancer-free survival in a good proportion of patients with cirrhosis and HCC, particularly when the cancers are incidental, or when diagnosed pre-LTx, conforming to established selection criteria. An active LTx programme for this group of patients is justified.

Adult↗

PubMed1999

Emotional responsivity and transient myocardial ischemia.

This study examined the relationship between "emotional responsivity" (i.e., individuals who exhibit relatively large variations of self-reported tension levels) and myocardial ischemia. One hundred thirty-six patients with coronary artery disease underwent 48 hr ambulatory electrocardiographic (ECG) monitoring and laboratory mental stress testing using radionuclide angiocardiography. Compared with individuals characterized as low emotional responders, a higher proportion of individuals characterized as high emotional responders exhibited wall motion abnormalities in response to laboratory mental stress testing and were more likely to exhibit ECG ST-segment depression (> or = 1 mm for > or = 1 min) during routine daily activities. These results suggest that emotional responsivity may represent an individual difference characteristic that is associated with an increased likelihood of exhibiting myocardial ischemia in both the laboratory and the real-world setting.

Adaptation, Psychological↗

PubMed1999

Intimate association of microsatellite repeats with retrotransposons and other dispersed repetitive elements in barley.

Simple sequence repeat (SSR)-based genetic markers are being actively developed for the majority of crop plant species. In barley, characterization of 290 dinucleotide repeat-containing clones from SSR-enriched libraries has revealed that a high percentage are associated with cereal retrotransposon-like and other dispersed repetitive elements. Associations found were with BARE-1, WIS2-1A, PREM1 and the dispersed repetitive element R173. Additional similarities between different SSR clones, which have no matches in DNA sequence databases, indicate that this phenomenon is probably widespread in the barley genome. Sequence homologies to the non-coding regions of several cereal genes were also explained by homology to mobile genetic elements. The SSRs found can therefore be classified into two types: (1) those with unique sequences on either flank, and (2) those which are intimately associated with retro-transposons and other dispersed repetitive elements. As the cereal genome is thought to consist largely of this type of DNA, some random association would be expected. However, the conserved positions of the SSRs, relative to repetitive elements, indicate that they have arisen non-randomly. Furthermore, this class of SSRs can be classified into three subtypes: (1) those which are positioned 3' of a transposable element with unique sequence on the other flank, (2) those positioned 5' of a transposable element, and (3) those which have arisen from an internal sequence and so have transposable element sequence on both flanks. The first appear to be analogous to the class of SSRs in mammalian systems which are associated with Alu elements and SINEs (short interspersed elements) and which have been postulated to arise following integration of an extended and polyadenylated retro-transcript into the host genome, followed by mutation of the poly(A) tract and expansion into an SSR. For the second, we postulate that a proto-SSR (A-rich sequence) has acted as a 'landing pad' for transposable element insertion (rather than being the result of insertion), while the third includes those which have evolved as a component of an active transposable element which has spread throughout the genome during bursts of transposition activity. The implications of these associations for genome and SSR evolution in barley are discussed.

Base Sequence↗

PubMed1999

Liver transplantation for hepatocellular carcinoma in cirrhotic patients.

BACKGROUND: Hepatocellular carcinoma (HCC) in patients with cirrhosis, due to a limited liver reserve, is often deemed unresectable, even at an early stage. METHODS: In order to evaluate the ongoing transplant programme for cirrhotic patients with HCC at Royal Prince Alfred Hospital, the results of liver transplantation (LTx) for HCC were analysed and the patient actuarial survival was compared with that of those LTx patients without malignancy. RESULTS: A total of 441 LTx were performed in 404 patients between January 1986 and April 1998. Twenty-four LTx recipients (22 men; two women) of mean age 49 (15-62) years had HCC. Twenty-one had underlying aetiology for their cirrhosis (hepatitis B: n = 9; hepatitis C: n = 8; hepatitis B and C: n = 1; haemochromatosis: n = 1; autoimmune hepatitis: n = 1; alcoholism: n = 1), while three patients had cryptogenic cirrhosis. Six patients had incidental tumours and another two cases were of the fibrolamellar type. The average tumour size and tumour number were 2.9 (0.4-11.5) cm and 1.3 (1-4), respectively. Operative mortality was 4.2% (1/24). The HCC recurrence appeared in one (4.2%) patient (with a 11.5-cm HCC) who died 18 months after LTx. A further two patients died (one graft failure from recurrent hepatitis C and one from fungal sepsis) during follow-up. The overall 1- and 3-year actuarial patient survival rates were 87% and 76%, respectively, and that of patients with benign causes (n = 369) were 77% and 72% (P = NS). CONCLUSION: With careful patient selection, long-term tumour-free patient survival can be achieved. The results support an active transplant programme for selected HCC.

Adolescent↗

PubMed1999

Rupture of abdominal aortic aneurysms: A concurrent comparison of outcome of those occurring after endoluminal repair versus those occurring de novo.

AIM: to compare the outcome of patients whose abdominal aortic aneurysm (AAA) ruptured following endoluminal repair with those whose AAA ruptured prior to treatment. PATIENTS: over a 4-year period 434 patients underwent treatment for AAA with conventional open (n=253) and endoluminal repair (n=181). Of those having open repair, 216 patients had elective operations while 41 had operations for ruptured AAA. Four patients with ruptured AAA had undergone endoluminal repair previously (Group I) while the remaining 37 patients ruptured de novo (Group II). The patients in both groups were similar in age and sex but differed clinically. All four patients in Group I had major medical co-morbidities versus 56% in Group II (p<0.05). All patients in group I had a known endoleak following endoluminal repair. All patients underwent open repair. RESULTS: the proportion of patients presenting with hypotension in Group I (1/4) was significantly less than in Group II (30/37). The difference in 30-day mortality for Group I (0%) compared with that for Group II (43%) was significant. The four patients in Group I remain alive and well at follow-up 22 months after operation. The outcome for Group I was better than Group II despite the higher incidence of medical co-morbidities. CONCLUSION: endoluminal AAA repair complicated by a persistent endoleak does not protect from rupture, which may not be accompanied by such major haemodynamic changes and high mortality as rupture de novo. Further long-term results in more patients are required to confirm this intermediate level of protection.

Aged↗

PubMed1999

Comparison of RAMP and SSR markers for the study of wild barley genetic diversity.

Two molecular marker technologies, random amplified microsatellite polymorphism (RAMP) and simple sequence repeats (SSR), were used to determine genetic diversity of 27 accessions of the wild barley Hordeum vulgare ssp. spontaneum. 19 primer combinations were used to generate RAMP fragments and 16 SSR loci were analysed. A high level of polymorphism was found with both kind of markers as revealed by the mean polymorphism information content (PIC) values obtained: 0.838 and 0.855 for RAMP and SSR, respectively. Genetic dissimilarities between genotypes were estimated from RAMP and SSR data. A lack of correlation was found between both sets of data. This was reflected in the two dendrograms obtained which presented accessions clustered differently. The results suggest that both sets of markers reveal genetic variation induced by different mechanisms. The dendrogram produced from the RAMP dissimilarity estimates showed most of the groups related to the geographic origin of the accessions.

Alleles↗

PubMed1999

Shortening of endografts during deployment in endovascular AAA repair.

PURPOSE: To evaluate the incidence and extent of length changes during implantation of endovascular grafts in a prospective study of patients undergoing endovascular abdominal aortic aneurysm (AAA) repair. METHODS: Data regarding the occurrence of intraoperative technical difficulties and device complications were recorded prospectively for the Vanguard or AneuRx self-expanding, bifurcated endovascular grafts in 64 patients (56 males; mean age 75 years). Graft length was measured in the sheath system before deployment and again immediately after deployment by fluoroscopic comparison to a graduated marking catheter. RESULTS: Graft shortening > or = 15 mm was documented in 22 (56%) of 39 Vanguard cases and 11 (44%) of 25 AneuRx endografts. Additional extension grafts were required to correct endoleak caused by inadequate graft length in 9 (14%) patients, but no conversion to open repair was necessary. CONCLUSIONS: There appears to be a high incidence of intraprocedural graft shortening with 2 current designs of self-expanding endoluminal grafts.

Aged↗

PubMed1999

Endotension: an explanation for continued AAA growth after successful endoluminal repair.

PURPOSE: To present and analyze several cases that illustrate persistent sac pressurization following endovascular abdominal aortic aneurysm (AAA) repair. METHODS AND RESULTS: Four patients with successful endovascular AAA exclusion presented in follow-up with an expanding aneurysm. Two had initial sac diameter decrease, but by 18 and 24 months, respectively, the AAA had enlarged and become pulsatile. There was no endoleak evident, but the proximal attachment stents had mig rated distally in both cases. One patient developed endoleak with aneurysm expansion at 6 months; contained rupture occurred at 12 months. The last case had slowly evolving aneurysm expansion over 36 months but no endoleak. All endografts were removed and successfully replaced with conventional grafts. Intrasac thrombus was implicated as the means of pressure transmission that precipitated AAA expansion in these cases. CONCLUSIONS: Excluded AAAs can increase in size owing to persistent or recurrent pressurization (endotension) of the sac even when there is no evidence of endoleak. One proposed mechanism is pressure transmission via thrombus that lines the attachment site. Endotension may also represent an indiscernible, very low flow endoleak that allows blood to clot at the source of leakage.

Aged↗

PubMed1998

Linkage analysis in tetraploid potato and association of markers with quantitative resistance to late blight (Phytophthora infestans).

We have constructed a partial linkage map in tetraploid potato which integrates simplex, duplex and double-simplex AFLP markers. The map consists of 231 maternal and 106 paternal markers with total map lengths of 990.9 cM and 484.6 cM. The longer of the two cumulative map lengths represents approximately 25% coverage of the genome. In tetraploids, much of the polymorphism between parental clones is masked by 'dosage' which significantly reduces the number of individual markers that can be scored in a population. Consequently, the major advantage of using AFLPs--their high multiplex ratio--is reduced to the point where the use of alternative multi-allelic marker types would be significantly more efficient. The segregation data and map information have been used in a QTL analysis of late blight resistance, and a multi-allelic locus at the proximal end of chromosome VIII has been identified which contributes significantly to the expression of resistance. No late blight resistance genes or QTLs have previously been mapped to this location.

Chromosome Mapping↗

PubMed1998

Isolation, characterisation and mapping of simple sequence repeat loci in potato.

Solanum tuberosum L. DNA sequences containing simple sequence repeat (SSR) motifs were extracted from the EMBL database, cDNA and selectively enriched small-insert DNA libraries. Enrichment was achieved using either triplex affinity capture or single-strand hybridisation selection. One hundred and twelve primer pairs which successfully amplified products of the correct size from potato DNA were ultimately designed and synthesised. Ninety-eight of these revealed length polymorphisms in a panel of four diploid and two tetraploid clones, in agreement with the high information content of this class of markers which has been found in other species. All of the markers were assigned a quality score of 1-5 based on their potential usefulness. Eighty-nine loci from 65 of the primer pairs were located on two genetic linkage maps of potato by segregation analysis of the amplified alleles. Fifty-two of the SSRs were clearly single locus. The maps were aligned using 23 SSR primer pairs and 13 RFLP loci mapped in both populations. The markers described constitute a class which should replace Restriction Fragment Length Polymorphisms (RFLP) as the markers of choice for future genetic studies in potato. The sequences of the primers, together with other information on these markers are provided.

Base Sequence↗