Environmental and Edaphic Factors that Influence Spring Dead Spot Epidemics.

Spring dead spot (SDS) (Ophiosphaerella spp.) is a soilborne disease of warm-season turfgrasses grown where winter dormancy occurs. The edaphic factors that influence where SDS epidemics occur are not well defined. A study was conducted during the spring of 2020 and repeated in the spring of 2021 on four 'TifSport' hybrid bermudagrass (Cynodon dactylon × transvaalensis) golf course fairways expressing SDS symptoms in Cape Charles, VA, U.S.A. SDS within each fairway was mapped from aerial imagery collected in the spring of 2019 with a 20 MP CMOS 4k true color sensor mounted on a DJI Phantom 4 Pro drone. Three disease intensity zones were designated from the maps (low, moderate, high) based on the density of SDS patches in an area. Disease incidence and severity, soil samples, surface firmness, thatch depth, and organic matter measurements were taken from 10 plots within each disease intensity zone from each of the four fairways (n = 120). Multivariate pairwise correlation analyses (P < 0.1) and best subset stepwise regression analyses were conducted to determine which edaphic factors most influenced the SDS epidemic within each fairway and each year. Edaphic factors that correlated with an increase in SDS or were selected for the best fitting model varied across holes and years. However, in certain cases, soil pH and thatch depth were predictors for an increase in SDS. No factors were consistently associated with SDS occurrence, but results from this foundational study of SDS epidemics can guide future research to relate edaphic factors to SDS disease development.

First Report of Grapevine leafroll-associated virus-2 and -3 in Texas Vineyards.

Grapevine leafroll disease (GLD), caused by the grapevine leafroll-associated viruses (GLRaVs, family Closteroviridae) is an important disease in all grapevine-growing regions of the world (2). It negatively affects vine vigor, fruit yield, and grape quality (e.g., sugar accumulation) (3). Typical disease symptoms include downward rolling of grape leaves accompanied by interveinal reddening in red-fruited varieties and interveinal chlorosis in white-fruited varieties (2). The state of Texas currently has over 275 commercial vineyards and acreage under grape production is expanding. Currently, there is limited information on the presence of either GLRaV-2 (genus Closterovirus) or GLRaV-3 (genus Ampelovirus) in this state. During the 2012 season, 19 individual, symptomatic grapevines (13 cv. Lenoir and 6 cv. Blanc du Bois) were sampled (14 petioles per vine) from one vineyard site in Richards, TX. Total nucleic acid was extracted from the samples as described before (5) and tested by RT-PCR using species specific primers to amplify a 334-bp fragment of the HSP70h gene of GLRaV-2 (L2 F: 5'-ATAATTCGGCGTACATCCCCACTT-3' and U2 R: 5'-GCCCTCCGCGCAACTAATGACAG-3') (1) and a 541-bp fragment of the HSP70h gene of GLRaV-3 (LC1 F: 5'-CGCTAGGGCTGTGGAAGTATT-3' and LC2 R: 5'-GTTGTCCCGGGTACCAGATAT-3') (4). Samples were also subjected to triple (TAS) and double (DAS) antibody sandwich ELISA for GLRaV-2 and GLRaV-3 using commercially available antibody test kits (AC Diagnostics, Fayetteville, AR). Five samples tested positive for GLRaV-2 and one for GLRaV-3, all from the variety Lenoir with no incidences of mixed infection. In addition to the RT-PCR and ELISA, the presence of GLRaV-2 and GLRaV-3 was confirmed by direct sequencing of select RT-PCR products, which was purified using the QIAquick PCR Purification kit (Qiagen Inc., CA). The sequencing took place at the Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA. GLRaV-2 isolate TX12 (GenBank Accession No. KF417612) and GLRaV-3 isolate TX9 (KJ545571) shared 85 to 100% and 94 to 100% nucleotide identity and 74 to 100% and 82 to 100% amino acid identity, respectively, with previously reported isolates from around the world. All samples tested negative for GLRaV-1, -4, -4 strain 5, and -4 strain 9 (4), suggesting that some of the symptomatic vines may have a different disease or abiotic disorder, such as a nutrient deficiency. To our knowledge, this is the first report of GLRaV-2 and GLRaV-3 in the state of Texas. References: (1) N. Bertazzon and E. Angelini. J. Plant Pathol. 86:283, 2004. (2) M. Fuchs et al. Plant Dis. 93:395, 2009. (3) L. Kovacs et al. Am. J. Enol. Vitic. 52:254, 2001. (4) F. Osman et al. J. Virol. Methods. 141:22, 2007. (5) A. Rowhani et al. Proc. ICVG (Adelaide). 13:82, 2000.

Memory of incomplete phase transitions from a random squares model.

We present a simple two-dimensional model for a phase transition, then study its predictions, in particular the memory properties. The direct transformation is modeled by randomly placing small squares, "nuclei", on an initially empty surface. Then, the nuclei expand ("grow") up to finite final sizes which are randomly chosen in a given range, while keeping their square shape. An important issue is the "interaction" which forces some squares to remain at smaller sizes if the surrounding squares get in the way of their growth. Interestingly, this naturally leads to quasiequal total area covered by the squares of each size after a complete direct transformation. Next, it is shown that the system "remembers" incomplete ("arrested") reverse transformations taking place in reversed order of the squares sizes. The memory is "encrypted" in the distribution of the squares sizes after a next direct transformation and manifests as a significant imbalance between the areas covered by the "big" and "small" (relative to the arrest size) squares. We are able to also reproduce the so-called "hammer effect" and the memorizing of multiple arrest points. Our model is particularly relevant for the thermal memory effect in shape memory alloys, and we actually borrowed many features from existing thermodynamic models addressing this effect. However, here we eliminate the explicit thermodynamics and end up with a statistical geometry model, presumably easier to reproduce.

Detection and genetic profiling of infectious hypodermal and haematopoietic necrosis virus (IHHNV) infections in wild berried freshwater prawn, Macrobrachium rosenbergii collected for hatchery production.

Infectious hypodermal and haematopoietic necrosis virus (IHHNV) has been detected widely in penaeid culture facilities in Asia and the Americas. IHHNV infection on sub-adult and postlarvae of the giant freshwater prawn, Macrobrachium rosenbergii which had caused up to 80% mortalities was first reported in Southeast Taiwan in 2006. In Malaysia, although, there has been no report on IHHNV infections in M. rosenbergii, preliminary work suggests that there is an urgent need to setup a screening protocol for IHHNV for both wild and cultured populations. In this study, polymerase chain reaction based screening was carried out on 30 randomly sampled berried wild M. rosenbergii before and after spawning. All samples did not showed any sign of IHHNV infection. However, the results showed that 20% of the samples were IHHNV positive. Sequence analysis of the amplified band using NCBI-BLAST showed that the putative IHHNV sequence had 98% nucleotide sequence (388 bp) identity with the IHHNV isolate AC-05-005 non-structural protein 1 gene and seven other IHHNV strains in the data bank further affirming the suggestion on the presence of IHHNV in wild freshwater prawn populations in Malaysia.

A Randomized Trial of Mycobacterium w in Severe Presumed Gram-Negative Sepsis.

BACKGROUND: Mycobacterium w (Mw), an immunomodulator, has been shown to resolve early organ failure in severe sepsis. RESEARCH QUESTION: Does Mw improve survival in patients with severe presumed gram-negative sepsis? STUDY DESIGN AND METHODS: This was a randomized, double-blind, placebo-controlled, parallel-group study conducted in ICUs of five tertiary care centers in India. We included consecutive patients (age ≥ 18 years) with presumed gram-negative sepsis in the study within 48 h of the first organ dysfunction. Patients in the treatment arm received 0.3 mL/d of Mw intradermally for 3 consecutive days, whereas the control arm received matching placebo. The primary outcome was 28-day all-cause mortality. The secondary outcomes were ventilator-free days, days receiving vasopressor therapy, ICU and hospital length of stay, nosocomial infection rate, antibiotic use duration, and delta Sequential Organ Failure Assessment (SOFA) score. RESULTS: We included 202 patients with severe sepsis (101 Mw, 101 placebo). The use of Mw significantly reduced the mortality (9/101 vs 20/101; estimate difference, 0.11 [95% CI, 0.01-0.21]; P = .04). We found no difference in ventilator-free days, days receiving vasopressor drugs, ICU length of stay, and the hospital length of stay. The time to mortality (median, 13 days vs 8.5 days) was significantly longer in the Mw than in the placebo arm. The delta SOFA score, rate of nosocomial infections, and antibiotic use duration were similar in the two arms. We found Mw to reduce significantly the odds (OR, 0.37 [95% CI, 0.15-0.9]) of mortality after adjusting for culture-positive sepsis, baseline SOFA score, age, and sex. INTERPRETATION: The use of Mw was associated with a significant reduction in mortality in patients with severe presumed gram-negative sepsis. Further studies are required to confirm our findings. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT02330432; URL: www.clinicaltrials.gov.

Transplantation of a New Biological Product in Rare Diseases, Such as Epidermolysis Bullosa: Response and Clinical Outcome.

BACKGROUND: Epidermolysis bullosa (EB) is a phenotypically diverse group of hereditary blistering disorders involving mutations in 20 different genes. Those debilitating disorders are currently incurable; however, there are a number of promising preclinical trials, where some treatments already approach the stage of early clinical trial. In this paper we introduce a novel surgical approach to the treatment of EB-induced ulcerations. The purpose of our study was to evaluate the safety and efficacy of a new biological dressing in the form of an allogenic human skin equivalent graft before using multipotent stem cells, classified as an advanced therapy medicinal product. METHODS: Implanted human acellular dermal matrices were prepared from the superficial layers of donated human skin. Scaffold sterilization was conducted via irradiation with the use of a linear electron accelerator. Following water-knife debridement, wounds were surgically covered with accordingly prepared grafts and dressed in burn-injury fashion. Subsequently, the wounds were monitored for infection and viability. RESULTS: Our data indicate that grafting as a potential new medicinal product was safe and effective in patients with rare diseases, such as EB, and may be used for stem cells to create new Advanced Therapy Medicinal Products. During a 200-day follow-up, we proved the safety of using human scaffolds (allogeneic graft) by observing no apparent infection or necrosis. Instead, we noted fewer required dressing changes, promoted wound healing, pain reduction, and an overall improvement in the quality of life in patients with EB. CONCLUSION: The protocol for grafting allogenic acellular epidermal sheets is the most promising treatment for severely affected skin areas in EB patients to date.

New Treatment of Wound Healing With Allogenic Acellular Human Skin Graft: Preclinical Assessment and In Vitro Study.

BACKGROUND: Nonhealing wounds can be a major clinical problem. Impaired wound healing is often related to massive tissue injury, concomitant wound healing deficiencies (chronic wounds), burn injury, or congenital conditions. We propose a novel biological dressing as an alternative surgical approach. The dressing is a form of an allogenic human skin graft equivalent with further use of allogeneic stem cells classified as an advanced therapy medicinal product. This new allogenic acellular human skin graft has been specifically developed to address the clinical indications for dressing wound lesions and promoting tissue repair in specific rare genetic diseases. METHODS: This case report illustrates the use of an acellular human skin allograft seeded with multipotent stem cells in the treatment of tissue injuries (burns), congenital conditions, and chronic wounds. Donor-tissue processing yields an acellular dermal matrix with integral collagen bundling and organization, as well as an intact basement membrane complex. RESULTS: Preclinical observations show prolonged viability of acellular human skin grafts with multipotent stem cells. This was confirmed with histological and electron-microscopic evaluation of biopsies, which demonstrated host-cell infiltration and neovascularization of the biological dressing. Moreover, the dressings were characterized by low immunogenicity, as confirmed by histology exam and T-cell proliferation assays in vitro. CONCLUSION: Our data confirmed the safety and efficacy of the evaluated acellular human skin grafts, which may be used in patients with rare diseases, such as epidermolysis bullosa, burn injuries, and chronic wounds.

Variation in Disease Incidence of Phomopsis Cane and Leaf Spot of Grape in Commercial Vineyards in Ohio.

A statewide survey for incidence of Phomopsis cane and leaf spot of grape (caused by Phomopsis viticola) was conducted during the 2002 to 2004 growing seasons. Over the 3 years, disease was observed in all surveyed vineyards, and mean disease incidence for leaves and internodes was 42 and 50%, respectively. A hierarchical linear mixed model was used to evaluate effects of region, farm within region, vineyard within farm, sampling site (i.e., vine) within vineyard, and shoot (i.e., cane) within vine on disease incidence. Region of the state did not have a significant effect on incidence but there was significant variation at all other levels of the hierarchy (P < 0.05); the greatest variation was at the lowest scale (shoots within vines). The potential effects of weather and management practices on disease risk at the vineyard scale were determined by using nonparametric correlation and binary logistic analyses after first classifying mean incidence per vineyard as being below or above 20% (D20 = 0,1) and 40% (D40 = 0,1). Overall results indicated that variables for predicted number of moderate infection events (DM; based on ambient temperature and hours when either there was measured rainfall or relative humidity above 90%), the extent of fungicide application (C) during early- and mid-May (M1 and M2, respectively), and the use of a dormant-period application of fungicide (DOR) were the key factors in predicting disease risk (for either D20 or D40). Accuracy (percentage of high and low disease vineyards correctly predicted) and area under the receiver operating characteristic curve (an overall measure of the accuracy of a model) for a generic model combining these predictor variables were 74 and 0.84, respectively, for D40 and 87 and 0.97, respectively, for D20. Models based on management practices were as accurate as those that incorporated weather variables. Although the degree of control of this disease is inadequate in Ohio, based on the survey results for incidence, the results from the risk-model analysis showed that improved management might be obtained by applying fungicide early during the growing season.

Comparison of Kidney Transplantation Results From the Same Deceased Donor Between Patients With the First Transplantation and Retransplanted Patients.

BACKGROUND: It has been determined that there are about 25% patients with renal allograft failure on the waiting lists. METHODS: We analyzed 406 patients who received a kidney graft from 2013 to 2015 in a single center. The analysis resulted in 33 pairs of patients: for one recipient in the pair it was the first transplantation and for the other it was the second or a subsequent one. Graft and patient survival, graft function, delayed graft function episodes, primary nonfunction, and acute rejection episodes were analyzed to assess the outcome of kidney retransplantation. The follow-up period was 2 years. Delayed graft function was observed in both groups (P = .3303). RESULTS: Although in the second group there were twice as many episodes of acute rejection than in the first group (8 to 4), the results are not statistically significant (P = .1420). Primary graft dysfunction was observed only in the second group. Five patients who had lost their kidney graft during the follow-up period were observed in the second group. The probability of graft loss in the second group was as follows: 3% on the day of the transplantation, 12% after 3 months, and 15% after 13 months. All of the patients survived during the 2-year follow-up period. A similar estimated glomerular filtration rate was observed in dialysis time in both groups. CONCLUSION: There are no statistically significant differences in kidney graft function between patients with the first transplantation and those with the repeat one. Good kidney transplantation results are attainable in both groups. It seems that retransplantation is the best treatment option for patients with primary graft failure.

Does Low Birthweight Have an Impact on Living Kidney Donor Outcomes?

INTRODUCTION: Because nearly 30,000 people worldwide become living kidney donors each year, donor safety is of the utmost importance. Recent studies have shown that living kidney donation is associated with an increased relative risk for end-stage renal disease (ESRD). It is essential to determine which donors will be more likely to develop ESRD. One of the risk factors for ESRD in living kidney donors is hypertension and, because there are studies demonstrating that low birthweight is a risk factor for developing hypertension in adult life, we hypothesized that donors with low birthweight may be at higher risk of developing renal disease after donation. METHODS: Seventy-three living kidney donors were examined. Donors were divided into 2 cohorts: a group with low birthweight and group with normal birthweight. We checked whether the donor birthweight has an impact on the outcome of donor renal function and on the development of hypertension. RESULTS: Hypertension was observed statistically more frequent in the group with low birthweight (P = .003). CONCLUSION: Glomerular filtration rate before kidney donation was found to be lower in the low-birthweight group.

Psychological Aspects of Living Kidney Donation in Poland: Experience of One Center.

BACKGROUND: Living kidney transplantation is the optimal treatment of end-stage renal disease. The benefits for recipients are obvious. The psychological consequences for living kidney donors in Poland are not known. OBJECTIVE: The objective of the study was to evaluate the psychological aspects of living kidney donation in Poland. PATIENTS AND METHODS: A total of 66 living donor open nephrectomies were performed in our institution between 1995 and 2005. The psychological aspects were assessed in 40 donors after nephrectomy. The study applied the Satisfaction With Life Scale (SWLS), the Situation Assessment Questionnaire, the Health Behaviors Survey, and our own questionnaire. The mean observation period was 65.6 months. RESULTS: There was a trend toward better life satisfaction in living kidney donors compared to Polish adults. Donor life satisfaction was significantly lower when the recipient was dead than when the recipient was alive. Most donors perceived the kidney donation as a challenge in cognitive judgment. The mean score of the Health Behaviors Survey was not significantly different than in the general population in Poland. The mean pain score after donation was 3.2 in a 5-item scale (1 = severe pain, 5 = mild pain). The mean time of return to work was 3.5 months. No donors regretted their decisions about kidney donation. CONCLUSION: Living kidney donation in Poland has a positive impact on donors' quality of life. Among living kidney donors, the sense of danger concerning the risk of donation depends on the degree of the relationship with the recipient.

Do Anatomical Anomalies Affect the Results of Living Donor Kidney Transplantation?

BACKGROUND: Multiple renal artery kidneys still represent a special challenge for surgeons, during both nephrectomy for organ donation and transplantation. Recognition of anatomical conditions with advanced imaging methods is one of the most important elements of the preoperative evaluation process. AIM: The purpose of the current study was to assess if anatomical abnormalities affect the outcomes of living kidney donor transplantation procedures. PATIENTS AND METHODS: A retrospective analysis of 60 living kidney donors and their recipients was performed. Patients were assigned to two groups: pairs with a single allograft vessels (group I) and pairs with any anatomical abnormalities of the transplanted organ (group II). The impact of anatomical abnormalities on initial and long-term outcomes of the transplantation were analyzed. RESULTS: The analyzed study group consisted of 60 pairs (35 included in group I and 25 in group II). Immediate graft function was observed in 65.7% vs 64% individuals, recpectively (n.s.). Mean serum creatinine concentration was 1.6, 1.46, and 1.44 mg/mL (group I) vs 1.78, 1.78, and 1.65 mg/mL (group II) at 1, 6, and 12 months posttransplant, respectively (n.s.). Glomerular filtration rate (using the Chronic Kindey Disease Epidemiology Collaboration equation) was estimated at 54.3, 59.9, and 61.0 mL/min/1.73 m2 (group I) vs 59.8, 57.6, and 59.8 mL/min/1.73 m2 (group II) at the same time points, respectively (n.s.). CONCLUSIONS: Presence of single renal vessels was not a predictor of immediate graft function in living-donor kidney transplantation. Transplantation outcomes for kidneys with anatomical anomalies did not differ when compared to organs with typical anatomy. Multiple renal arteries did not impact initial graft function if precise surgical technique and proper preoperative diagnostics were provided.

Effects of Application of Fungicide During the Dormant Period on Phomopsis Cane and Leaf Spot of Grape Disease Intensity and Inoculum Production.

Efficacy of application of the fungicides calcium polysulfide or fixed copper during the dormant period on control of Phomopsis cane and leaf spot of grape (Vitis spp.), caused by Phomopsis viticola, was examined under field conditions during the 2003 and 2004 growing seasons in Ohio. Dormant-period fungicide applications were made either in the fall (after leaf drop and periderm tissue formation on the first-year canes, mid-November), or spring (at bud-swell, mid-April), or both. Disease incidence and severity on leaves and internodes were examined. In addition, effects of dormant-period application on sporulation of P. viticola were determined by examining the number of conidia in rain-splashed water in the spring and formation of mature pycnidia on cane sections in the winter. Fall-and-spring and spring applications of calcium poly-sulfide provided 12 to 88% reduction in disease intensity (incidence or severity), whereas calendar-based protectant mancozeb applications reduced overall disease intensity by 47 to 100%. Fixed-copper applications did not provide a consistent reduction of the disease. Fall applications of dormant-period fungicide provided little or no effect by itself. There was a significantly lower number of conidia observed in collected splashed rain water from vines treated with fall-and-spring applications of calcium polysulfide than in rain water from nonsprayed vines. Fall-and-spring and spring applications of calcium polysulfide provided a significant reduction in the number of mature pycnidia formed on incubated cane sections compared with the nonsprayed control (5 versus 10 pycnidia/cm2), whereas fixed copper did not provide a significant reduction.

Evaluation of a Disease Warning System for Phomopsis Cane and Leaf Spot of Grape: A Field Study.

A field evaluation of a warning system for Phomopsis cane and leaf spot of grape (Vitis spp.), caused by Phomopsis viticola, was conducted in Ohio over 3 years (2002 to 2004) by applying fungicides and fungicide-adjuvant combinations based on predicted infection events. Three different criteria for risk-light, moderate, and high-were evaluated with the warning system. The warning system is based on measured weather conditions (temperature and wetness duration following rain) and a model for risk of leaf and internode infection. Vines were sprayed with fungicides based on either the warning system or a calendar-based 7-day protectant program, from 2.5-cm shoot growth (Eichhorn-Lorenz [E-L] stage 7) to the end of the broom (E-L stage 27). Fungicides were tested with or without an adjuvant (JMS Stylet-Oil or Regulaid). In the controls, the mean percentage of leaves and internodes with infections ranged from 36 to 100%, the number of lesions per leaf ranged from 1 to 28, and percentage of internodes covered by lesions ranged from 1 to 12%. Both the calendar-based protectant treatment (based on use of mancozeb) and the warning system treatment based on spraying in response to light or moderate predicted infection events (especially with mancozeb + Regulaid) resulted in significantly less disease incidence and severity compared with the controls. The mean percent control (relative difference in disease between a treatment and the control) was higher for the protectant schedule (˜55% and ˜80% for incidence and severity, respectively, based on application of mancozeb) than for the warning system (˜36% and ˜60% for incidence and severity, respectively, based on application of mancozeb + Regulaid), but there were two to three times more fungicide applications with the protectant schedule than with the warning system.

Alterations of gene expression during colorectal carcinogenesis revealed by cDNA microarrays after laser-capture microdissection of tumor tissues and normal epithelia.

To identify a set of genes involved in the development of colorectal carcinogenesis, we compared expression profiles of colorectal cancer cells from eight tumors with corresponding noncancerous colonic epithelia using a DNA microarray consisting of 9216 human genes. These cell populations had been rendered homogeneous by laser-capture microdissection. Expression change in more than half of the tumors was observed for 235 genes, i.e., 44 up-regulated and 191 down-regulated genes. The differentially expressed genes include those associated with signal transduction, metabolizing enzymes, production of reactive oxygen species, cell cycle, transcription, mitosis, and apoptosis. Subsequent examination of 10 genes (five up-regulated and five down-regulated) by semiquantitative reverse transcription-PCR using the eight tumors together with an additional 12 samples substantiated the reliability of our analysis. The extensive list of genes identified in these experiments provides a large body of potentially valuable information of colorectal carcinogenesis and represents a source of novel targets for cancer therapy.

Reliability and accuracy of visual estimation of phomopsis leaf blight of strawberry.

ABSTRACT Six different individuals (raters) assessed the severity of Phomopsis leaf blight on strawberry leaflets in five experimental repetitions over 2 years by making a direct visual estimation of the percentage of diseased area of each leaflet or by using the Horsfall-Barratt (H-B) disease scale. Intra-rater and inter-rater reliability and accuracy were determined, and then the relationship between visually estimated severity values and actual severity values was evaluated. Agreement in estimated disease severity values between assessment times by the same raters (i.e., intra-rater reliability), and agreement in disease severity values among raters at a single assessment time (i.e., inter-rater reliability), were both high, with most correlation coefficients being greater than 0.85. The intra-class correlation for overall agreement among raters ranged from 0.80 to 0.96 for the five repetitions. Based on the concordance coefficient calculated for each rater in each repetition, agreement between estimated and actual severity (i.e., accuracy) was somewhat lower than reliability. The relationship between estimated and actual severity was linear, and there was a slight trend to overestimate disease severity. The H-B scale was not more reliable or accurate than direct estimation of severity, and the linear relationship between estimated and actual severity did not support the principles underling the H-B scale. Both size of leaflets and number of lesions per leaflet slightly affected the error in estimate of disease severity.

Extended versus limited lymph nodes dissection technique for adenocarcinoma of the stomach.

BACKGROUND: Surgeons disagree about the merits and risks of radical lymph node clearance during gastrectomy for cancer. OBJECTIVES: To evaluate survival and peri-operative mortality after limited or extended lymph node removal during gastrectomy for cancer. SEARCH STRATEGY: We searched MEDLINE, EMBASE, CancerLit, LILACS, Central Medical Journal Japanese Database and the Cochrane register, references from relevant articles and conference proceedings. We contacted known workers in the field. SELECTION CRITERIA: Studies published after 1970 which reported 5 year survival or postoperative mortality rates, and clearly defined the node dissection performed, were considered. We excluded studies which overtly included patients receiving perioperative chemotherapy, and comparisons with clear systematic treatment allocation bias. Randomised controlled trials (RCTs), non-randomised comparisons and observational studies were considered separately. DATA COLLECTION AND ANALYSIS: Three reviewers selected trials for inclusion. Quality assessment and data extraction were performed independently by two reviewers. Results of trials of similar design were pooled. Meta-analysis was performed separately for randomised and non-randomised comparisons. MAIN RESULTS: Two randomised and two non-randomised comparisons of limited (D1) versus extended (D2) node dissection and 11 cohort studies of either D1 or D2 resection were analysed. Meta-analysis of randomised trials did not reveal any survival benefit for extended lymph node dissection (Risk ratio = 0.95 (95% CI 0.83 - 1.09), but showed increased postoperative mortality (RR 2.23, 95% CI 1.45 - 3.45). Pre-specified subgroup analysis suggested a possible benefit in stage T3+ tumours (RR = 0.68, 95% CI 0.42-1.10). Non-randomised comparisons showed no significant survival benefit for extended dissection (RR 0.92, 95% CI 0.83 -1.02), but decreased mortality (RR 0.65, 95% CI 0.45-0.93). Subgroup analysis showed apparent benefit in UICC stage II and IIIa. Observational studies of D2 resection reported much better mortality and survival than those of D1 surgery, but the settings were strikingly different. REVIEWERS' CONCLUSIONS: D2 dissection carries increased mortality risks associated with spleen and pancreas resection, and probably with inexperience and low case volumes. Randomised studies show no evidence of overall survival benefit, but possible benefit in T3+ tumours. These results may be confounded by surgical learning curves and poor surgeon compliance. Non-randomised comparisons suggest a possible survival benefit for D2 in intermediate UICC stages. Observational studies show high 5 year survival and low operative mortality after D2 dissection in experienced units, and poor results after D1 dissection in non-specialist units. Further studies, with precautions to eliminate learning curve effects, contamination and non-compliance, are needed to evaluate D2 dissection in intermediate stage gastric cancer.