Spatiotemporal Patterns in the Airborne Dispersal of Spinach Downy Mildew.

Downy mildew is the most devastating disease threatening sustainable spinach production, particularly in the organic sector. The disease is caused by the biotrophic oomycete pathogen Peronospora effusa, and the disease results in yellow lesions that render the crop unmarketable. In this study, the levels of DNA from airborne spores of P. effusa were assessed near a field of susceptible plants in Salinas, CA during the winter months of 2013-14 and 2014/15 using rotating-arm impaction spore-trap samplers that were assessed with a species-specific quantitative polymerase chain reaction (qPCR) assay. Low levels of P. effusa DNA were detectable from December through February in both winters but increased during January in both years, in correlation with observed disease incidence; sharp peaks in P. effusa DNA detection were associated with the onset of disease incidence. The incidence of downy mildew in the susceptible field displayed logistic-like dynamics but with considerable interseason variation. Analysis of the area under the disease progress curves suggested that the 2013-14 epidemic was significantly more severe than the 2014-15 epidemic. Spatial analyses indicated that disease incidence was dependent within an average range of 5.6 m, approximately equivalent to the width of three planted beds in a typical production field. The spatial distribution of spores captured during an active epidemic most closely fit a power-law distribution but could also be fit with an exponential distribution. These studies revealed two important results in the epidemiology of spinach downy mildew in California. First, they demonstrated the potential of impaction spore-trap samplers linked with a qPCR assay for indicating periods of high disease risk, as well as the detection of long-distance dispersal of P. effusa spores. Second, at the scale of individual crops, a high degree of spatial aggregation in disease incidence was revealed.

Season-Long Dynamics of Spinach Downy Mildew Determined by Spore Trapping and Disease Incidence.

Peronospora effusa is an obligate oomycete that causes downy mildew of spinach. Downy mildew threatens sustainable production of fresh market organic spinach in California, and routine fungicide sprays are often necessary for conventional production. In this study, airborne P. effusa spores were collected using rotating arm impaction spore trap samplers at four sites in the Salinas Valley between late January and early June in 2013 and 2014. Levels of P. effusa DNA were determined by a species-specific quantitative polymerase chain reaction assay. Peronospora effusa was detected prior to and during the growing season in both years. Nonlinear time series analyses on the data suggested that the within-season dynamics of P. effusa airborne inoculum are characterized by a mixture of chaotic, deterministic, and stochastic features, with successive data points somewhat predictable from the previous values in the series. Analyses of concentrations of airborne P. effusa suggest both an exponential increase in concentration over the course of the season and oscillations around the increasing average value that had season-specific periodicity around 30, 45, and 75 days, values that are close to whole multiples of the combined pathogen latent and infectious periods. Each unit increase in temperature was correlated with 1.7 to 6% increased odds of an increase in DNA copy numbers, while each unit decrease in wind speed was correlated with 4 to 12.7% increased odds of an increase in DNA copy numbers. Disease incidence was correlated with airborne P. effusa levels and weather variables, and a receiver operating characteristic curve analysis suggested that P. effusa DNA copy numbers determined from the spore traps nine days prior to disease rating could predict disease incidence.

The Hepatitis C virus treatment cascade at an urban postincarceration transitions clinic.

Transitions clinics, which provide medical care to individuals who have been released from incarceration, reach a population at high risk for hepatitis C Virus (HCV) infection. We used the HCV treatment cascade to describe HCV care at an urban postincarceration transitions clinic, identifying gaps in care and determining reasons for lapses in care. In this retrospective cohort study, we reviewed electronic health records for all formerly incarcerated individuals receiving care at the Bronx Transitions Clinic. HCV treatment cascade measures included the following: detection of HCV antibodies, confirmation of chronic infection, specialist referral, specialist evaluation, initiation of treatment, completion of treatment and achievement of SVR. We recorded reasons for lapses in care. Of 451 patients accessing care, 317 (70%) were screened for HCV antibodies, and 106 (33%) tested positive. Of the 106 antibody-positive patients, 93 (88%) were evaluated for HCV viremia and 84 (79%) were confirmed to have chronic HCV infection; 19% of the total sample had chronic HCV infection. Of these 84 with chronic HCV, 48 (57%) received specialist referral, 30 (36%) were evaluated, 8 (10%) initiated treatment, and 5 (6%) completed treatment and achieved SVR. Some treatment lapses occurred because patients were deemed unstable for treatment (12%) or were re-incarcerated (5%). Chronic HCV infection was common among transitions clinic patients. Few were treated and cured. Patients lost contact with providers before consideration for antiviral therapy. Referral to specialty providers was a gap in care. Increasing HCV treatment in this population will likely require intensive delivery models.

Decision aids for multiple-decision disease management as affected by weather input errors.

Many disease management decision support systems (DSSs) rely, exclusively or in part, on weather inputs to calculate an indicator for disease hazard. Error in the weather inputs, typically due to forecasting, interpolation, or estimation from off-site sources, may affect model calculations and management decision recommendations. The extent to which errors in weather inputs affect the quality of the final management outcome depends on a number of aspects of the disease management context, including whether management consists of a single dichotomous decision, or of a multi-decision process extending over the cropping season(s). Decision aids for multi-decision disease management typically are based on simple or complex algorithms of weather data which may be accumulated over several days or weeks. It is difficult to quantify accuracy of multi-decision DSSs due to temporally overlapping disease events, existence of more than one solution to optimizing the outcome, opportunities to take later recourse to modify earlier decisions, and the ongoing, complex decision process in which the DSS is only one component. One approach to assessing importance of weather input errors is to conduct an error analysis in which the DSS outcome from high-quality weather data is compared with that from weather data with various levels of bias and/or variance from the original data. We illustrate this analytical approach for two types of DSS, an infection risk index for hop powdery mildew and a simulation model for grass stem rust. Further exploration of analysis methods is needed to address problems associated with assessing uncertainty in multi-decision DSSs.

Spleno-renal bypass facilitating endovascular stenting of a juxta-renal aortic aneurysm in a high risk patient.

The management of juxta-renal abdominal aortic aneurysms (AAA) is challenging. Open surgical repair is associated with significant morbidity (predominantly renal) and the absence of an adequate length of normal infra-renal aorta precludes the placement of a standard endograft. In high-risk patients who are unsuitable for standard open repair the endovascular options include fenestrated or branched stent grafts, which are complex, expensive and not widely available, especially in the acute setting. In this report, we describe a case of a hybrid endovascular graft utilising a spleno-renal bypass to facilitate the supra-renal fixation of an aorto-bi-iliac endovascular stent graft in a high-risk patient.

Utilization of GIS/GPS-Based Information Technology in Commercial Crop Decision Making in California, Washington, Oregon, Idaho, and Arizona.

Ground-based weather, plant-stage measurements, and remote imagery were geo-referenced in geographic information system (GIS) software using an integrated approach to determine insect and disease risk and crop cultural requirements. Weather forecasts and disease weather forecasts for agricultural areas were constructed with elevation, weather, and satellite data. Models for 6 insect pests and 12 diseases of various crops were calculated and presented daily in georeferenced maps for agricultural areas in northern California and Washington. Grape harvest dates and yields also were predicted with high accuracy. The data generated from the GIS global positioning system (GPS) analyses were used to make management decisions over a large number of acres in California, Washington, Oregon, Idaho, and Arizona. Information was distributed daily over the Internet as regional weather, insect, and disease risk maps as industry-sponsored or subscription-based products. Use of GIS/GPS technology for semi-automated data analysis is discussed.

Experience with heparin-bonded collagen-coated grafts for infrainguinal bypass.

The perfect conduit for infrainguinal reconstructive surgery does not exist. When autologous vein is not available, then a prosthetic graft must be used. The use of a heparin-bonded graft has the theoretical advantage of reducing smooth muscle cell proliferation and thrombus formation, thereby reducing occlusion rates. The application of a collagen layer to the external surface of the graft serves to reduce transfabric haemorrhage. Forty-six patients underwent 47 infrainguinal reconstructions using heparin-bonded collagen-coated Dacron grafts over a 4-year period. Twenty grafts were for disabling claudication and 27 for critical ischaemia. Twenty-two grafts were to the above knee popliteal artery (47%), 10 to the below knee popliteal (21%) and 15 to one of the crural vessels (32%). There was a cumulative patency at 4 years of 69% for the above knee grafts, and 30-month patency of 58% and 45% for the below knee and crural grafts, respectively. There were three deaths over the study period and eight patients required major amputations.

The results of thoracoscopic sympathetic trunk transection for palmar hyperhidrosis and sympathetic ganglionectomy for axillary hyperhidrosis.

OBJECTIVES: To review our total experience of thoracoscopic sympathetic trunk transection for the treatment of palmar hyperhidrosis and second and third thoracic sympathetic ganglionectomy for axillary hyperhidrosis. DESIGN: Longitudinal cohort study following up consecutive patients for 0.3 to 5.5 years. SUBJECTS: Fifty-four consecutive patients undergoing thoracoscopic sympathectomy for hyperhidrosis. METHODS: Prospective evaluation of immediate technical success, complications, late recurrence of hyperhidrosis and patient acceptability. RESULTS: 100% initial cure for palmar hyperhidrosis, 91% of sympathetic ganglionectomies for axillary hyperhidrosis were technically successful and initially curative. Compensatory sweating 44% patients, most severe after bilateral sympathetic ganglionectomy. Complications occurred in 14% patients, all resolving without further intervention. There were no cases of Horner's syndrome. 13% patients reported a return of some palmar sweating. 5.4% patients developed recurrent palmar hyperhidrosis at 6, 15 and 21 months postoperatively. CONCLUSION: Transection of the sympathetic trunk between the first and second thoracic sympathetic ganglia initially cures 100% of patients treated primarily for palmar hyperhidrosis. Technically successful 2nd and 3rd thoracic sympathetic ganglionectomy initially cures 100% of patients with axillary hyperhidrosis. Compensatory sweating is common after bilateral sympathectomy. Recurrent palmar hyperhidrosis occurs in 5.4% of cases, but can be cured by a second thoracoscopic sympathectomy. Horner's syndrome is an avoidable complication of thoracoscopic sympathectomy.

Acute upper limb ischemia: a complication of coronary artery bypass grafting.

We present the case of a patient with acute upper limb ischemia after radial artery harvest for coronary artery bypass grafting. This occurred despite adequate preoperative and intraoperative assessment with the Allen test, hand-held Doppler and radial artery backbleeding. A successful outcome was achieved by performing brachioradial bypass grafting using reversed cephalic vein.

Age-related outcome for peripheral thrombolysis.

OBJECTIVES: To investigate the age-related outcome of peripheral thrombolysis and determine for which patient group this treatment is worthwhile. DESIGN AND METHODS: A combined retrospective and prospective analysis of consecutive patients undergoing thrombolysis for acute lower-limb ischaemia was made with respect to age-related outcome and other risk factors. RESULTS: One hundred and two patients underwent thrombolysis for acute limb ischaemia. In the under 60 age group there was a 40% amputation rate. Seventy-three per cent of this group smoked. In the over 80 age group, the amputation rate was 15% and only 8% were smokers. CONCLUSION: Advancing age is not an adverse risk factor for thrombolysis which appears to be safe and effective in this patient group. There is a high incidence of smoking in the younger age group (< 60 years), in whom failed thrombolysis frequently leads to amputation.

The incorporation of a stent-graft into the porcine aorta and the inflammatory response to the endoprosthesis.

The fate of a non-sutured anastomosis and the inflammatory response to an endoprosthesis in a porcine aorta was determined. Self-expanding aorto-aortic endovascular prostheses were deployed into the infrarenal aorta of Large White pigs by the transfemoral route, in accordance with Home Office regulations. Animals were followed up at intervals to 1 year. The aortas were explanted and specimens were subjected to light microscopy. Thirteen animals, mean weight 103 kg, underwent placement of a prosthesis. There was early evidence of a neointima at 4 weeks and a well-developed neointima by 12 weeks, with complete incorporation of the endoprosthesis. The early acute inflammatory reaction seen at 4 weeks had become chronic by 12 and was largely absent by 26 weeks. There was no evidence of atypia. Complete incorporation of the non-sutured anastomosis is seen in this model. The acute inflammatory reaction to the prosthesis seen at 4 weeks had largely subsided by 26 weeks.

Photoplethysmography can replace hand-held Doppler in the measurement of ankle/brachial indices.

Ankle/brachial pressure index (ABPI) using hand-held Doppler and sphygmomanometer is a standard assessment for patients with peripheral arterial occlusive disease (PAOD). Good Doppler technique is difficult to master and so we investigated replacing Doppler with photoplethysmography (PPG). Two investigators examined 52 legs in 32 vascular patients. Both used standard sphygmomanometer cuff occlusion. Restoration of flow was detected by either an 8 MHz Doppler ultrasound probe or a PPG transmitter/receiver on index finger or great toe. Doppler-derived ABPIs were compared with PPG-derived ABPIs. Excellent correlation was found between both indices (correlation coefficient 0.875). Four lower limbs had unrecordable PPG traces, one also having an unrecordable Doppler signal. Excluding these four patients, the correlation coefficient rose to 0.975. PPG placed on the pulp of a digit can replace the hand-held Doppler in measuring ABPIs.

Full-dose and half-dose Klean Prep produce clearer images with iliac duplex examination than picolax.

OBJECTIVES: Iso-osmotic bowel preparation (Klean Prep) improves the accuracy of iliac duplex examination and reduces the time of each examination. Full-dose Klean Prep entails 4 l of fluid. We studied the effect of 2 l of Klean Prep (half-dose) and Picolax on image quality. DESIGN: Prospective study comparing clarity of duplex examination after three different bowel preparation regimes with that after 12 h starvation. MATERIALS AND METHODS: Thirty patients underwent iliac duplex examination after 12 h starvation. Scans were scored subjectively for grey scale and colour image quality, and Doppler signal-to-noise ratio. Patients were allocated blindly to: (a) full-dose Klean Prep, (b) half-dose Klean Prep, or (c) Picolax. After out-patient preparation, the scan was repeated and scored by the same observer, blinded to the preparation. RESULTS: Both full- and half-dose Klean Prep produced significant improvements in image quality for all three modalities; Picolax produced minimal change. There was minimal advantage of full-dose over half-dose Klean Prep. Patients preferred half-dose Klean Prep to full-dose. CONCLUSION: Klean Prep significantly improves the image obtained by iliac duplex examination; Picolax does not. Half-dose Klean Prep is an acceptable preparation to patients.

The effects of simulated spring goose grazing on the growth rate and protein content of Phleum pratense leaves.

The effects of simulated goose grazing on Phleum pratense plants were tested in an Iceland hayfield during the spring goose staging period (19 April-11 May 1997). Plants in an area exclosed from the influence of grazing and the nutrient effects of goose faeces were subject to the removal of the youngest lamina once, three and four times during this period. Clipping three and four times resulted in 25-41% increases in cumulative elongation of youngest laminae compared with unclipped plants. Total cumulative lamina growth of entire plants showed no significant difference between unclipped plants and those clipped three and four times, hence no overcompensation occurred. Sequential clipping elevated the protein content of the youngest laminae from 20% to 27-33%, whereas there was no change amongst shoots clipped only once. Because geese only consume the youngest lamina of each Phleum plant, measurements from this experiment showed that regular physical removal of growing biomass doubled the biomass of preferred tissue available to geese and increased the potential protein intake 3.5 times at experimental clipping frequencies similar to levels of sequential harvesting observed amongst staging geese compared to less frequent harvesting. These increases were achieved without any fertilising effects of goose faeces implicated in such effects in previous studies.

Career aspirations and expectations of vascular trainees in 1996. The Rouleaux Club.

Sub-specialisation within general surgery has now become accepted as part of surgical training and consultant posts are being increasingly advertised for surgeons with a special interest. Transplantation surgery is currently losing trainees and proposals have been made to combine vascular and transplant surgery to a greater or lesser degree. The Rouleaux Club is a society for junior vascular surgeons in Great Britain and Ireland. Questionnaires were sent to 78 non-consultant members in July 1996 and 67 were returned and analysed. A reasonable cross-section of all training grades was obtained. Of this number 44 (65.7 per cent) did not want to spend any period of their higher surgical training in full-time transplantation training, although 32 (47.8 per cent) would accept some time in transplantation training if it were combined with another surgical specialty. Training in vascular access work was welcomed by 51 (76.1 per cent) but this contrasts with 40 (59.7 per cent) who would not want to offer this as a service once appointed to consultancy. Almost all of the trainees (60/64 = 93.8 per cent) ideally wanted to be appointed to consultant posts with > 50 per cent commitment to vascular surgery and most thought that they would realistically get such positions. Most trainees ideally wanted consultancies in academic/ university departments or teaching hospitals but many thought that in reality they would be appointed to posts in district general hospitals.