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.

Common and Low Frequency Variants in MERTK Are Independently Associated with Multiple Sclerosis Susceptibility with Discordant Association Dependent upon HLA-DRB1*15:01 Status

Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. The risk of developing MS is strongly influenced by genetic predisposition, and over 100 loci have been established as associated with susceptibility. However, the biologically relevant variants underlying disease risk have not been defined for the vast majority of these loci, limiting the power of these genetic studies to define new avenues of research for the development of MS therapeutics. It is therefore crucial that candidate MS susceptibility loci are carefully investigated to identify the biological mechanism linking genetic polymorphism at a given gene to the increased chance of developing MS. MERTK has been established as an MS susceptibility gene and is part of a family of receptor tyrosine kinases known to be involved in the pathogenesis of demyelinating disease. In this study we have refined the association of MERTK with MS risk to independent signals from both common and low frequency variants. One of the associated variants was also found to be linked with increased expression of MERTK in monocytes and higher expression of MERTK was associated with either increased or decreased risk of developing MS, dependent upon HLA-DRB1*15:01 status. This discordant association potentially extended beyond MS susceptibility to alterations in disease course in established MS. This study provides clear evidence that distinct polymorphisms within MERTK are associated with MS susceptibility, one of which has the potential to alter MERTK transcription, which in turn can alter both susceptibility and disease course in MS patients.

Multiple sclerosis (MS) is the most common neurological disease of young Caucasian adults. Oligodendrocytes are the key cell type damaged in MS, a process that is accompanied by loss of the myelin sheath that these cells produce, resulting in demyelination and ultimately in secondary damage to nerve cells. Susceptibility to MS is strongly influenced by genes, and over 100 genes have now been linked with the risk of developing MS. However, surprisingly little is known about the biological mechanism by which any one of these genes increases the probability of developing MS. In this study we have explored in detail the links between one known MS risk gene, MERTK, and MS susceptibility. We found that a number of different alterations in the MERTK gene are independently associated with the risk of developing MS. One these changes was also linked with changes in the level of expression of MERTK in monocytes, an immune cell type known to be involved in the etiology of MS. In an unexpected result, we found this expression-linked alteration in MERTK was either protective or risk-associated, depending on the genotype of the individual at another well known MS risk gene known as HLA-DRB1. In addition, we found that not only were alterations in MERTK associated with MS susceptibility, but potentially with ongoing disease course, indicating that MERTK may be a good target for the development of novel MS therapeutics.

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.

Connectedness of PPI network neighborhoods identifies regulatory hub proteins

MOTIVATION

With the growing availability of high-throughput protein-protein interaction (PPI) data, it has become possible to consider how a protein's local or global network characteristics predict its function.

RESULTS

We introduce a graph-theoretic approach that identifies key regulatory proteins in an organism by analyzing proteins' local PPI network structure. We apply the method to the yeast genome and describe several properties of the resulting set of regulatory hubs. Finally, we demonstrate how the identified hubs and putative target gene sets can be used to identify causative, functional regulators of differential gene expression linked to human disease.

AVAILABILITY

Code is available at http://bcb.cs.tufts.edu/hubcomps.

CONTACT

fox.andrew.d@gmail.com; slonim@cs.tufts.edu

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

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.

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.

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.

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.

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.

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.

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.

Comparison of magnetic resonance imaging measurements of abdominal aortic aneurysms with measurements obtained by other imaging techniques and intraoperative measurements: possible implications for endovascular grafting

PURPOSE

Abdominal aortic aneurysm morphologic evaluation with conventional imaging techniques is inadequate when endovascular repair is being contemplated. This study has addressed the problem with magnetic resonance imaging (MRI).

METHODS

Twenty patients (14 men, 6 women) with a median age of 73 years were recruited and assessed according to current endovascular graft selection criteria. Thirteen patients subsequently underwent open aneurysmorrhaphy, and the intraoperative parameters have been compared with those of duplex ultrasonography and MRI.

RESULTS

No significant difference was demonstrated in the diameter of the infrarenal neck among ultrasonography, MRI, and intraoperative findings (p > 0.05, Mann Whitney U Test) and also during assessment of infrarenal neck length; however, duplex sonography accurately defined the renal ostia in only five cases. MRI visualized 38 of 40 renal arteries. Distal aortic involvement (cuff diameter and length) and the length and diameter of the common iliac arteries were accurately determined by MRI in all cases, and no significant difference was demonstrated with the intraoperative findings. Comparison of the intraoperative and MRI aneurysm lengths suggested a slight trend of overestimation by MRI resulting from angulation of the aneurysm, but this figure did not reach statistical significance. Only two patients met the current criteria for endoluminal straight grafting.

CONCLUSIONS

Both MRI and duplex sonography accurately predicted aortic morphologic characteristics; however, MRI provided the most comprehensive anatomic picture for patient selection and should be considered the nonionizing imaging modality of choice when an endovascular repair is being contemplated.

Intraoperative duplex scanning as a means of quality control during carotid endarterectomy

OBJECTIVES

To identify correctable technical errors following carotid endarterectomy using intraoperative colour duplex sonography (ATL, UM9, HDI). Results were compared with intraoperative flow measurements using an operative flow meter and with middle cerebral artery velocity measured by trans-cranial Doppler (TCD).

DESIGN

Prospective study.

MATERIALS AND METHODS

50 consecutive patients undergoing carotid endarterectomy were investigated. Follow-up was performed at 6 weeks using duplex scanning and clinical evaluation.

RESULTS

Significant intraoperative technical errors were detected in three patients and were re-explored. Two scans demonstrated kinking or pinching at the distal endarterectomy site requiring patch-plasty and the third revealed a large mass of intramural thrombus. A further 18 endarterectomies yielded 21 additional minor abnormalities.

CONCLUSIONS

Duplex sonography provides a sensitive intraoperative technique for detecting thrombus and technical errors. It yields both anatomic and hemodynamic details and is superior to intraoperative flow measurements and transcranial doppler.

Peroperative cholangiography through the gallbladder (cholecystocholangiography) during laparoscopic cholecystectomy

The indications and best technique for peroperative cholangiography during laparoscopic cholecystectomy remain unclear, but the operation has been associated with an increased use of preoperative endoscopic retrograde cholangiography. Cystic duct cholangiography, particularly in the hands of the trainee, can be time consuming, and bile duct injury may be caused by attempts to cannulate the cystic duct. This study analyses 113 consecutive patients undergoing peroperative cholangiography through the gallbladder, or cholecystocholangiography. It was successful in 92 (81.4%) patients, the procedure adding less than 10 min to the operating time. There were no cholangiogram-related complications. Common anatomical variations included both short and particularly wide cystic ducts. This information helps to minimize the risk of damage to the common bile duct. This study demonstrates that cholecystocholangiography is a safe, simple, and effective alternative to cystic duct cholangiography with virtually no "learning curve." It provides a "road-map" of biliary anatomy and identifies common bile duct stones prior to the commencement of dissection. Unsuccessful cholecystocholangiography does not preclude the use of cystic duct cholangiography later in the operation. Difficult anatomy is demonstrated prior to dissection. When unsuspected bile duct calculi necessitate open exploration, further laparoscopic dissection is avoided.

Iso-Osmotic Bowel Preparation Improves the Accuracy of Iliac Artery Colour Flow Duplex Examination

Colour flow duplex ultrasonography is currently the non-invasive method of choice for investigating the iliac arteries. However it is only 84–92% sensitive in the best hands when compared with biplanar angiography. Bowel gas and faeces overlying the iliac arteries obscure the vessels and prevent a good ultrasound image.

We have previously shown that preparation of the bowel with an iso-osmotic bowel preparation (Klean Prep) improves the clarity of duplex image of the iliac arteries. This is caused by a volume effect which flushes out gas and faeces, leaving a fluid-filled bowel transparent to ultrasound. The aim of this study was to investigate whether this enhanced image increased the diagnostic accuracy of duplex examination.

We performed iliac duplex examinations on 56 patients with clinically suspected iliac artery disease, initially with the normal preparation of starving the patients for 12 h and subsequently after preparation by Klean Prep. The results from each investigation were compared with the gold standard of biplanar intra-arterial digital substraction angiography.

The use of iso-osmotic bowel preparation (Klean Prep) significantly improved the accuracy of iliac duplex ultrasonography over preparation by 12 h starvation, when compared with biplanar angiography.

Do-it-yourself femoropopliteal bypass

A 74-year-old male claudicant had undergone operative repair of his bilateral varicose veins 22 years earlier. His records confirmed that on the right side he had only had a saphenofemoral disconnection. Duplex scanning and angiography of his right leg demonstrated an occluded superficial femoral artery (SFA) and a network of channels between the proximal SFA stump and the long saphenous vein (LSV). Distal SFA reconstitution occurred through two distal arteriovenous fistulas. We believe that this is the first case of a spontaneous femorodistal bypass graft secondary to neovascularisation recorded in the literature.

Aortic valvulitis complicating Wegener's granulomatosis

In a case of Wegener's granulomatosis aortic valve replacement was performed for worsening congestive cardiac failure secondary to aortic incompetence. Two paravalvular lesions and an isolated intraleaflet deficiency of the non-coronary cusp were identified at operation. Histological changes were consistent with a connective tissue disease.

Reversed vein graft stenosis: early diagnosis and management

Conscientious surveillance of intrainguinal bypass grafts is mandatory to detect vein graft stenoses, which, if uncorrected, can lead to graft occlusion. It is now widely accepted that noninvasive vascular laboratory studies are the best way to detect these lesions. However, controversy still exists over treatment, specifically whether balloon angioplasty is an acceptable substitute for surgery (patch angioplasty or short jump grafts) in the treatment of these lesions. We have always favored balloon angioplasty as primary treatment and have summarized our experience with treating 72 stenotic reversed femoropopliteal and femorotibial vein grafts, which represent 12% of 521 bypass grafts performed at our institution. Prosthetic and in situ grafts are specifically excluded from this report, as well as occluded grafts, found to have stenotic lesions after lytic therapy. The most common stenotic lesion occurred within 4 cm of the proximal anastomosis (29/72 = 40%). The other sites were near the distal anastomosis (7/72 = 10%), and in the middle of the graft (15/72 = 12%). Eighty-one percent (58/72) of the lesions were treated initially by balloon angioplasty with a 31% recurrence. Twenty-nine percent of the 14 grafts treated surgically by vein patch angioplasty or short jump grafts experienced recurrence. Overall 61% (44/72) of the stenotic grafts were treated by balloon angioplasty alone. The 5-year life-table assisted primary patency after correction of the stenotic lesion was 61%. The patency of the grafts from the time of initial bypass surgery, however, was 80%. Location of the stenosis within the graft was a major determinant of patency. Lesions in the proximal graft, proximal anastomosis, and distal graft taken as a group had significantly better patency than the midgraft and distal anastomotic lesions (5-year patency, 65% vs 48%, p less than 0.001 log rank test). We continue to recommend balloon angioplasty as primary therapy for vein graft stenosis except for those occurring in the midgraft and distal anastomosis. Fortunately, this group accounts for only 36% of lesions seen with reversed veins. Recurrent stenosis after balloon angioplasty should be repaired surgically.

Thoracoabdominal aneurysm resection after previous infrarenal abdominal aortic aneurysmectomy

Thoracoabdominal aneurysms in 51 patients were repaired over 5 years ending in February 1991. Fourteen (27%, 14 of 51) patients had a prior infrarenal aneurysm resection (PRA); their data are analyzed separately. The average age of patients who had undergone PRA was 67 years (range: 56 to 86 years). The mean aneurysm diameter was 8.6 cm (range: 5 to 12 cm), and the mean time interval between initial aneurysm surgery and subsequent resection of the thoracoabdominal aneurysm was 8.5 years (range: 2 to 17 years). Three patients in the PRA group were operated on emergently, two because of clinical evidence of rupture; the other patients underwent elective repair. Early mortality (30 days) in the PRA group was significantly related to age (72 years or older versus younger than 72 years: 75% versus 10%, p = 0.04), proximal extent of aneurysm (above diaphragm versus below diaphragm: 50% versus 0%, p = 0.05), ruptured aneurysm (ruptured versus nonruptured: 100% versus 16%, p = 0.06), and a cardiac history of myocardial infarction (57% versus 0%, p = 0.03), congestive heart failure (66% versus 0%, p = 0.01), or arrhythmia (80% versus 0%, p = 0.005). Similar results were seen with the entire group of patients with thoracoabdominal aneurysms except that the proximal extent of the aneurysm was not related to mortality. These results demonstrate that thoracoabdominal aneurysm resection after prior infrarenal aneurysmectomy is not associated with increased mortality or morbidity.

Experimental short-bowel syndrome: effect of an elemental diet supplemented with short-chain triglycerides

To determine whether short-chain triglycerides (SCTs, 1:1 triacetin:tributyrin, wt:wt) enhance intestinal adaptation in short-bowel syndrome (SBS), male Sprague-Dawley rats underwent 60% distal small-bowel resection with cecectomy and received either a chemically defined diet (CD) or a CD containing 40% of nonprotein energy as either medium-chain triglycerides (MCTs) or SCTs. After 12 d the SCT group had significantly increased jejunal mucosal weight compared with the MCT and CD groups and had significantly increased segment weight and mucosal protein compared with the CD group. In the colon the SCT group had significantly increased segment and mucosal weights and mucosal protein and DNA compared with both the MCT and CD groups. Body-weight change and measurements of serum ketones, albumin, glucose, and triglycerides revealed no significant differences among groups. SCTs improved jejunal and colonic adaptive growth and maintained comparable nutritional status in SBS when compared with CD alone or CD with MCTs.

Stimulation of intestinal mucosal growth with intracolonic infusion of short-chain fatty acids

Dietary fiber, which stimulates intestinal mucosal growth, is fermented by anaerobic bacteria in the rat hindgut to the short-chain fatty acids (SCFA) acetate, propionate, and butyrate. Butyrate is the preferred oxidative fuel of the colonocyte in vitro, and the provision of preferred intestinal fuels has been shown to stimulate mucosal proliferation in vivo. This study determined whether chronic colonic infusion of butyrate or a combination of SCFA would stimulate intestinal mucosal growth in an animal deprived of its normal source of SCFA, fiber fermentation in the cecum. Adult male Sprague-Dawley rats were fed a fat- and fiber-free elemental liquid diet and underwent cecectomy, ileocolic anastomosis, and insertion of a proximal colonic infusion catheter. Rats were then assigned to receive either a continuous infusion of butyrate (20 mM, 40 mM, or 150 mM), SCFA (70 mM acetate + 35 mM propionate + 20 mM butyrate), or saline, or to receive no infusion. A seventh group underwent proximal colonic transection and reanastomosis. After 7 days, jejunal, ileal, and proximal colonic segments were analyzed for mucosal weight, protein, RNA, and DNA. In the colon, the 40-mM butyrate infusion resulted in significant elevations in all mucosal parameters relative to all three control groups, saline infusion, no infusion, and transection. Both the 20-mM butyrate and the SCFA groups showed increased colonic mucosal DNA compared to controls. In the jejunum and ileum, mucosal DNA content was significantly greater in the SCFA group than in the control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a glutamine-supplemented enteral diet on methotrexate-induced enterocolitis

Administration of an elemental diet to rats given methotrexate (MTX), 20 mg/kg intraperitoneally (ip), results in 100% mortality from severe enterocolitis. Previous studies indicate that glutamine (GLN), which is not present in elemental diets, is the preferred oxidative substrate for the gut and may facilitate intestinal recovery after injury. This study investigated the effects of a glutamine-supplemented elemental diet (GLN-ED) on nutritional status, intestinal morphometry, bacterial translocation and survival in this lethal model of intestinal injury. Three experiments were performed. In the first experiment, rats received an intragastric elemental diet supplemented with either 2% GLN or an equivalent amount of glycine (Control). After 4 days animals received either MTX, 20 mg/kg ip, or saline ip and were killed 3 days later. The GLN-ED resulted in significantly decreased weight loss, improved nitrogen retention, and increased mucosal weight, protein, and DNA content of the jejunum and colon. In the second experiment rats were assigned to diet as in the first experiment, but all animals received MTX. Control diet animals died within 120 hrs of MTX administration. The GLN-ED group had significantly longer survival time and decreased mortality. In the third experiment animals were assigned to diet and MTX as in the first experiment. Ninety-six hrs later aortic blood cultures revealed enteric bacteremia in animals administered MTX. GLN-ED resulted in a significant reduction in the incidence of bacteremia. These experiments showed that a GLN-ED significantly improved nutritional status, decreased intestinal injury, decreased bacterial translocation, and resulted in improved survival in a lethal model of enterocolitis.

Dexamethasone administration induces increased glutaminase specific activity in the jejunum and colon

Exogenous glucocorticoids markedly increase the in vivo uptake and utilization of glutamine by the intestine. Since glutamine is the major oxidative fuel for the small intestine, we investigated whether glucocorticoids induce changes in the specific activity of the enzymes that mediate glutamine degradation (glutaminase) and synthesis (glutamine synthetase). Male Sprague-Dawley rats received a 7-day elemental diet. On Day 5, animals were randomized to one of four groups and received either saline (Control) or one of three doses of dexamethasone im: 0.1 mg/kg (Lodex); 0.3 mg/kg (Middex); or 0.6 mg/kg (Hidex). Forty-eight hours later jejunal and colonic segments were assayed for protein, glutaminase, and glutamine synthetase activity. A stress dose of dexamethasone (Hidex) produced a significant increase in both jejunal and colonic glutaminase specific activity (P less than 0.02 vs Control and P less than 0.05 vs Control, respectively). These data suggest a mechanism whereby glucocorticoids increase the intestinal utilization of glutamine by increasing the specific activity of intestinal glutaminase.

Inhibition of TPN-associated intestinal mucosal atrophy with monoacetoacetin

Total parenteral nutrition (TPN) is associated with intestinal mucosal atrophy. Acetoacetate is oxidized in preference to glucose by both enterocytes and colonocytes and is not present in TPN. The purpose of this study was to determine whether replacement of a portion of glucose calories with monoacetoacetin, the glycerol ester of acetoacetate, could inhibit TPN-associated intestinal atrophy. Male Sprague-Dawley rats (200-250 g) underwent superior vena caval cannulation and were assigned to receive chow ad libitium (CHOW), TPN with 0.86 M monoacetoacetin (ACAC), or TPN with 0.86 M glycerol to control for the glycerol component of monoacetoacetin (GLYC). Nitrogen balance was measured over 7 days after which time the animals were weighed and sacrificed. Jejunal and colonic segments were harvested and the mucosal weight, protein, RNA, and DNA contents measured. All groups showed comparable weight gain. Cumulative nitrogen balance was positive for both TPN groups. Significant decreases in mucosal parameters occurred in both TPN groups compared to the CHOW group, but atrophy was significantly inhibited in both jejunum and colon of the ACAC group compared to the GLYC group. Thus, the substitution of monoacetoacetin for glucose calories in parenteral nutrition solutions inhibited TPN-related atrophy of intestinal mucosa while maintaining normal growth.

Successful suicide by self-inflicted multiple stab wounds of the skull, abdomen, and chest

A case is presented of a 53-year-old white male who successfully committed suicide by stabbing himself in the abdomen and chest, after which he was driven 11 km (seven miles) to a church without anybody noticing his wounds. In the church he finished his task by stabbing himself through the calvarium.

Acute hemolytic anemia secondary to infectious mononucleosis

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