A low mutation rate for chloroplast microsatellites.

We used chloroplast simple sequence repeats (cpSSRs) to examine whether there is any variation present in the chloroplast genome of Pinus torreyana (Parry ex Carrière) that may previously not have been detected using RFLPs. Analysis of 17 cpSSR loci showed no variation, which is consistent with previous cpRFLP work and confirms that the species is descended from an original, highly monomorphic population following a bottleneck. This lack of biological variation in the chloroplast genome of P. torreyana allowed us to estimate the mutation rates at cpSSR loci as between 3. 2 x 10(-5) and 7.9 x 10(-5). This estimate is lower than published mutation rates at nuclear SSR loci but higher than substitution rates elsewhere in the chloroplast genome.

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.

Gene-pool variation in caledonian and European Scots pine (Pinus sylvestris L.) revealed by chloroplast simple-sequence repeats.

We have used polymorphic chloroplast simple-sequence repeats to analyse levels of genetic variation within and between seven native Scottish and eight mainland European populations of Scots pine (Pinus sylvestris L.). Diversity levels for the Scottish populations based on haplotype frequency were far in excess of those previously obtained using monoterpenes and isozymes and confirmed lower levels of genetic variation within the derelict population at Glen Falloch. The diversity levels were higher than those reported in similar studies in other Pinus species. An analysis of molecular variance (AMOVA) showed that small (3.24-8.81%) but significant (p < or = 0.001) portions of the variation existed between the populations and that there was no significant difference between the Scottish and the mainland European populations. Evidence of population substructure was found in the Rannoch population, which exhibited two subgroups. Finally, one of the loci studied exhibited an allele distribution uncharacteristic of the stepwise mutation model of evolution of simple-sequence repeats, and sequencing of the PCR products revealed that this was due to a duplication rather than slippage in the repeat region. An examination of the distribution of this mutation suggests that it may have occurred fairly recently in the Wester Ross region or that it may be evidence of a refugial population.

Polymorphic chloroplast simple sequence repeat primers for systematic and population studies in the genus Hordeum

In this study we report the development of primers to amplify polymorphic chloroplast simple sequence repeats in the genus Hordeum, which includes cultivated barley (H. vulgare ssp. vulgare) and its wild progenitor H. vulgare ssp. spontaneum. Polymorphic products were amplified in a wide range of Hordeum spp. and intraspecific variation was detected in both cultivated and wild barley. A decrease in cytoplasmic diversity was observed between sspp. spontaneum and vulgare as well as between ssp. vulgare landraces and cultivars, which is characteristic of domestication processes in many corp species. We also observed possible evidence for reticulate evolution of H. brachyantherum polyploids, with apparent multiple cytoplasmic introgressions during successive polyploidization events.

Amplified fragment length polymorphism (AFLP) analysis of genetic variation in Moringa oleifera Lam

Moringa oleifera is an important multipurpose tree introduced to Africa from India at the turn of this century. Despite limited knowledge of the levels of genetic diversity and relatedness of introduced populations, their utilization as a source of seed for planting is widespread. In order to facilitate reasoned scientific decisions on its management and conservation and prepare for a selective breeding programme, genetic analysis of seven populations was performed using amplified fragment length polymorphism (AFLP) markers. The four pairs of AFLP primers (PstI/MseI) generated a total of 236 amplification products of which 157 (66.5%) were polymorphic between or within populations. Analysis of molecular variance (AMOVA) revealed significant differences between regions and populations, even though outcrossing perennial plants are expected to maintain most variation within populations. A phenetic tree illustrating relationships between populations suggested at least two sources of germplasm introductions of Kenya. The high levels of population differentiation detected suggest that provenance source is an important factor in the conservation and exploitation of M. oleifera genetic resources.

Circular indurated lymphangitis of the penis.

Circular lymphangitis of the penis has been seen in three of our patients, two of whom complained of mild discomfort. A patient with syphilis was initially misdiagnosed because of similar clinical findings. A serologic test for syphilis should be performed in all patients with this disorder.

Reliability and validity of the objective structured clinical examination in assessing surgical residents.

The purpose of this research was to assess reliability and construct validity of the objective structured clinical examination (OSCE) for evaluating the clinical skills of surgical residents. Reliability refers to precision of the examination and construct validity to the degree to which the examination can discriminate between different levels of training. Twenty-seven second postgraduate year surgical residents took a 38-station OSCE representing seven surgical specialties and that tested history-taking, physical examination, problem-solving, technical skills, and attitudes. A couplet methodology was used wherein a patient encounter was followed by written questions aimed at testing problem-solving and patient management capabilities. Thirty-six standardized patients were trained and 36 surgeons served as examiners marking from structured checklists. Overall reliability, Cronbach's alpha, was 0.89. Construct validity was examined by comparing the scores of the residents with those of a group of graduates of foreign medical schools applying for a "pre-internship" program. For 17 of 19 stations that both groups took, the residents performed significantly better (p less than 0.01). Individual station validity was significant for 32 of 38 stations (r = 0.36 to 0.82, p less than 0.05). The examinations took 3.83 hours at a cost of $5,293 (Canadian dollars). The OSCE has been shown to be a reliable method of assessing clinical skills of surgical residents, construct validity has been established, and inter-item validity confirmed. Reliabilities achieved exceed those traditionally required for both acceptance and promotion decisions.

Postoperative tonsillectomy pain in pediatric patients: electrocautery (hot) vs cold dissection and snare tonsillectomy--a randomized trial.

OBJECTIVE: To determine the effect of the method of tonsillectomy on postoperative pain in pediatric patients. DESIGN: Prospective, randomized, single-blind, controlled clinical trial. SETTING: A university pediatric hospital in Aberdeen, Scotland. PATIENTS: A volunteer sample of 54 children, aged 3 to 12 years, with recurrent tonsillitis or symptomatic adenotonsillar hypertrophy. Two patients withdrew consent. INTERVENTIONS: Twenty-six children underwent a nonelectrical (ie, cold) dissection tonsillectomy with cold steel instruments, 5 of whom also had adenoidectomy by curettage. Monopolar diathermy forceps were used for tonsillar bed hemostasis. Twenty-four children had electrocautery (ie, hot) dissection tonsillectomy, 7 of whom underwent adenoidectomy by curettage without a suction coagulator. MAIN OUTCOME MEASURES: Postoperative analgesic consumption, time to regain normal diet and activity levels, and complications. RESULTS: Patients who underwent hot dissection tonsillectomy showed no difference in time to first drink or analgesic use within the first 24 postoperative hours compared with children undergoing cold nonelectrical dissection tonsillectomy. The hot dissection tonsillectomy group took 7.5 (95% confidence interval [CI], 1-14.1) more doses of analgesics than the cold dissection group over the next 12 days (P<.05). The hot dissection tonsillectomy group took 2.5 more days than the cold dissection tonsillectomy group to regain normal diet (P<.05). Thirteen children (54%; 95% CI, 34-74) in the hot dissection tonsillectomy group and 6 (23%; 95% CI, 7-39) in the cold dissection tonsillectomy group sought outpatient care for throat pain, otalgia, poor diet, pyrexia, and/or bleeding (P<.05). Throat pain delayed in onset or of prolonged duration affected 9 children (38%; 95% CI, 19-57) in the hot dissection tonsillectomy group as opposed to 3 children (12%; 95% CI, 0-24) in the cold dissection tonsillectomy group (P<.05). CONCLUSION: Hot dissection tonsillectomy increases morbidity in pediatric patients in the recovery period following hospital discharge.

Infected arterial grafts: clinical manifestations and surgical management.

The clinical manifestations and results of management in twenty-five patients treated for infected vascular grafts are reviewed. The overall incidence of infection in this series of prosthetic grafts is 1.4%. Staphylococcus aureus was found to be the single most common infecting organism and multiple organisms were found in nine patients. Therapy was divided into three methods of management: local therapy alone resulted in a mortality of 45% and an amputation rate of 36.3%; partial graft excision resulted in a mortality of 20% and an amputation rate of 60%; total graft excision resulted in a mortality of 22% and an amputation rate of 22% as well. All amputations were above-knee amputations and the most common cause of death was continuing sepsis. The overall mortality of 32% and a loss of limb rate of 44% are testimony to the serious nature of this problem.

Selection of amputation level and prediction of healing using transcutaneous tissue oxygen tension (PtcO2).

Pre-operative measurement of transcutaneous tissue oxygen tension (PtcO2) by reflecting oxygen delivery at proposed amputation sites may allow accurate prediction of post-operative healing. Thirty-eight patients requiring amputation had PtcO2 measured with a Clark electrode on the foot, anteriorly and posteriorly below knee and above the knee while lying supine. PtcO2 greater than 24 mmHg was chosen to predict healing and indicated 13 above-knee (AK) and 25 below-knee (BK) amputations. Clinical criteria indicated 12 AK and 26 BK amputations. PtcO2 and clinical judgement differed on five occasions, a lower amputation was indicated by PtcO2 twice and by clinical selection three times (PtcO2 16 mmHg). Amputation was performed at the more distal level indicated (25 BK, 13 AK). Foot PtcO2 in both groups did not differ significantly, 4.08 +/- 2.00 mmHg (BK) and 3.9 +/- 1.29 mmHg (AK) (p greater than 0.5), nor did above knee PtcO2 (p greater than 0.3). Anterior below knee PtcO2 in both groups differed significantly, 34.92 +/- 10.84 mmHg (BK) and 9.5 +/- 5.60 mmHg (AK) (p less than 0.001). Likewise, posterior PtcO2, 39.64 +/- 6.85 mmHg (BK) and 14.1 +/- 4.43 mmHg (AK) (p less than 0.001). Amputation sites healed primarily within two weeks except the site with a pre-operative PtcO2 of 16 mmHg, where healing was delayed and occurred by second intention. These results indicate that PtcO2 is a valid predictor of primary healing following amputation.

Unusual aneurysms of the extracranial carotid artery.

Aneurysms of the extracranial internal carotid artery are rare and only 4 cases have been treated at the Wellesley Hospital since 1969. These aneurysms usually present as a painless lump in the neck and the 4 cases to be described manifest unusual presentations. One patient with a history of facial sepsis presented in the Emergency Department with what was thought to be a neck abscess. This was incised and drained before the true nature of the swelling was appreciated. Two patients presented with nerve palsies, one with a hypoglossal palsy due to stretching of the hypoglossal nerve over a large aneurysm and the second with recurrent laryngeal nerve palsy as a result of rupture of a false aneurysm from disruption of a saphenous vein patch inserted following carotid endarterectomy 9 months earlier. The fourth patient presented with a carotid bruit and had a stenosis distal to the aneurysm. Although rare, carotid aneurysms require recognition and early treatment if neurological sequelae are to be avoided.

Etiology and management of aorto-femoral bypass graft failure.

Over a nine-year period 1973 to 1982, 364 aorto-bifemoral bypass grafts were inserted for aorto-iliac occlusive disease and 45 graft failures were encountered. Twelve patients developed acute graft occlusion, occurring less than 30 days postoperatively (Group I). These failures were almost all due to technical problems, the most common cause was elevation of an intimal flap following local endarterectomy. Five patients (Group II) developed recurrent symptoms without actual thrombosis or occlusion of the graft, but were associated with neointimal hyperplasia at the distal anastomosis and evidence of distal atherosclerosis. Twenty-eight patients were late failures (Group III). These patients thrombosed their grafts more than 30 days postoperatively. Four patients thrombosed both limbs of the graft at separate intervals. Nineteen patients were found to have progressive atherosclerosis affecting their run-off vessels. Six patients were found to have stenosis limited to the distal anastomosis. False aneurysm, kinking of the graft, and proximal suture line stenosis were felt to be determining factors in 3 other incidences of graft failure. The most common treatment in Group I was thrombectomy and securing of the raised intimal flap. The patients in Group II were treated with local endarterectomy and patch angioplasty. Of the patients in Group III, the most common inflow procedure was thrombectomy, carried out in 17 cases. In Group III, 13 of 28 patients underwent profundaplasty to improve outflow. The importance of pre and postoperative angiography in defining the etiology of graft failure is stressed. It is important to rule out problems with the proximal anastomosis. Once inflow has been established, angiography should ensure that an adequate outflow procedure has been performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictors of surgical outcome in patients undergoing aortobifemoral bypass reconstruction.

We report a prospective study with 2 years of follow-up including 105 consecutive symptomatic patients (58.1% claudication and 41.9% severe ischemia) undergoing aortobifemoral bypass surgery (ABF/BP). Proportional-hazards, stepwise regression, and life-table analyses were used to determine predictors of the following outcome criteria: graft patency, amputation, mortality, symptomatic recurrence, and palliation. The operative mortality was 5.7% and the 2-year cumulative mortality was 15.5%. Most deaths (61.5%) were cardiac-related. There were 3 predictors of mortality: the presence of more than 1 surgical risk factor (relative risk [RR] 6.2; p less than 0.001), advanced age (RR 2.9; p = 0.03) and the presence of ischemic heart disease (RR 1.5; p = 0.045). No patient required amputation. Early graft patency rate was 94.3% and the 2-year cumulative patency was 92.8%. The only predictor of graft failure was preoperative ankle/brachial index (ABI) of less than 0.4 (RR 6.1; p = 0.003). Early symptomatic relief was 98.1% and at 2 years it was 77.3%. There were 2 predictors of symptomatic recurrence: postoperative smoking (RR 2.4; p less than 0.001) and impaired runoff (RR 2.5; p = 0.017). Cumulative palliation was 87.6% at 1 month and 66.5% at 2 years postoperatively. There were 2 predictors of palliation: the presence of more than 1 surgical risk-factor (RR 1.8; p = 0.001) and postoperative transcutaneous oximetry (PtcO2) of less than 35 mmHg (RR 3.1; p = 0.04). We conclude that the best predictors of outcome in patients undergoing ABF/BP surgery were the number of preoperative risk factors, age, ischemic heart disease, ABI, PtcO2, postoperative smoking, and angiographic runoff.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of cigarette smoking on outcome of femoral popliteal bypass for limb salvage.

A retrospective 5-year follow-up study of 83 femoral-popliteal bypass operations for severe ischemia (79 patients) is presented. There were no operative deaths. At one month, cumulative patency rates (CPR) and limb salvage rates (LSR) were 86.8% and 96.4% respectively. At 5 years, CPR, LSR and cumulative survival were 50%, 79.4% and 71.6% respectively. Post-operative smoking habits were strongly related to CPR and LSR. Smoking more than 5 cigarettes per day adversely affected CPR's. At 5 years, CPR of non-smokers and smokers of up to 5 cigarettes per day (47 patients) was 67.7% and for smokers of more than 5 cigarettes per day (32 patients) it was 44.7% (P less than 0.045). Smoking more than 15 cigarettes per day had an adverse effect on LSR's. Smokers of more than 15 cigarettes per day (17 patients) had a 5-year LSR of 58.5% compared with 89% for non-smokers and smokers of up to 15 cigarettes per day (62 patients) (P = 0.009). For 20 limbs requiring thrombectomy LSR was 100% at 1 year and 57.5% at 5 years. CPR's and LSR's were not significantly influenced by pre-operative smoking, diabetes, run off or level of distal anastomosis relative to the knee joint. Based on zero operative mortality and 96.4% limb salvage at 1 year, it is concluded that an aggressive approach toward revascularization for limb salvage is well justified in most patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure of bicycle exercise electrocardiograms to predict major post-operative cardiac complications in patients undergoing abdominal aortic surgery.

To determine if exercise electrocardiograms (EECGs) are justified in routine pre-operative screening for cardiac disease, we performed a prospective study on 77 consecutive patients scheduled for infrarenal aortic reconstructive surgery. All patients had EECGs performed 1-12 days prior to elective surgery. In addition to routine clinical assessment of cardiac disease, all patients were allocated a Goldman risk score. Four patients developed major post-operative cardiac complications of whom one patient died. EECG was not a significant predictor of outcome, as 48.6% of all EECGs were inadequate due to non-completion of the exercise protocol. Significant pre-operative predictors of outcome were a history of angina (p less than 0.01), myocardial infarction (p less than 0.001), congestive cardiac failure (p less than 0.0001), or a Goldman score of greater than 14 (p less than 0.05). By multivariate analysis of the pre-operative risk factors a history of congestive cardiac failure was found to be the most significant independent predictor of post-operative cardiac complications.

A fast algorithm for computing geodesic distances in tree space.

Comparing and computing distances between phylogenetic trees are important biological problems, especially for models where edge lengths play an important role. The geodesic distance measure between two phylogenetic trees with edge lengths is the length of the shortest path between them in the continuous tree space introduced by Billera, Holmes, and Vogtmann. This tree space provides a powerful tool for studying and comparing phylogenetic trees, both in exhibiting a natural distance measure and in providing a euclidean-like structure for solving optimization problems on trees. An important open problem is to find a polynomial time algorithm for finding geodesics in tree space. This paper gives such an algorithm, which starts with a simple initial path and moves through a series of successively shorter paths until the geodesic is attained.