Predicting mental and psychomotor delay in very pre-term infants using machine learning

BACKGROUND

Very preterm infants are at elevated risk for neurodevelopmental delays. Earlier prediction of delays allows timelier intervention and improved outcomes. Machine learning (ML) was used to predict mental and psychomotor delay at 25 months.

METHODS

We applied RandomForest classifier to data from 1109 very preterm infants recruited over 20 years. ML selected key predictors from 52 perinatal and 16 longitudinal variables (1-22 mo assessments). SHapley Additive exPlanations provided model interpretability.

RESULTS

Balanced accuracy with perinatal variables was 62%/61% (mental/psychomotor). Top predictors of mental and psychomotor delay overlapped and included: birth year, days in hospital, antenatal MgSO4, days intubated, birth weight, abnormal cranial ultrasound, gestational age, mom's age and education, and intrauterine growth restriction. Highest balanced accuracy was achieved with 19-month follow-up scores and perinatal variables (72%/73%).

CONCLUSIONS

Combining perinatal and longitudinal data, ML modeling predicted 24 month mental/psychomotor delay in very preterm infants ½ year early, allowing intervention to start that much sooner. Modeling using only perinatal features fell short of clinical application. Birth year's importance reflected a linear decline in predicting delay as birth year became more recent.

IMPACT

Combining perinatal and longitudinal data, ML modeling was able to predict 24 month mental/psychomotor delay in very preterm infants ½ year early (25% of their lives) potentially advancing implementation of intervention services. Although cognitive/verbal and fine/gross motor delays require separate interventions, in very preterm infants there is substantial overlap in the risk factors that can be used to predict these delays. Birth year has an important effect on ML prediction of delay in very preterm infants, with those born more recently (1989-2009) being increasing less likely to be delayed, perhaps reflecting advances in medical practice.

Four-Month Rifapentine Regimens with or without Moxifloxacin for Tuberculosis

BACKGROUND

Rifapentine-based regimens have potent antimycobacterial activity that may allow for a shorter course in patients with drug-susceptible pulmonary tuberculosis.

METHODS

In an open-label, phase 3, randomized, controlled trial involving persons with newly diagnosed pulmonary tuberculosis from 13 countries, we compared two 4-month rifapentine-based regimens with a standard 6-month regimen consisting of rifampin, isoniazid, pyrazinamide, and ethambutol (control) using a noninferiority margin of 6.6 percentage points. In one 4-month regimen, rifampin was replaced with rifapentine; in the other, rifampin was replaced with rifapentine and ethambutol with moxifloxacin. The primary efficacy outcome was survival free of tuberculosis at 12 months.

RESULTS

Among 2516 participants who had undergone randomization, 2343 had a culture positive for Mycobacterium tuberculosis that was not resistant to isoniazid, rifampin, or fluoroquinolones (microbiologically eligible population; 768 in the control group, 791 in the rifapentine-moxifloxacin group, and 784 in the rifapentine group), of whom 194 were coinfected with human immunodeficiency virus and 1703 had cavitation on chest radiography. A total of 2234 participants could be assessed for the primary outcome (assessable population; 726 in the control group, 756 in the rifapentine-moxifloxacin group, and 752 in the rifapentine group). Rifapentine with moxifloxacin was noninferior to the control in the microbiologically eligible population (15.5% vs. 14.6% had an unfavorable outcome; difference, 1.0 percentage point; 95% confidence interval [CI], -2.6 to 4.5) and in the assessable population (11.6% vs. 9.6%; difference, 2.0 percentage points; 95% CI, -1.1 to 5.1). Noninferiority was shown in the secondary and sensitivity analyses. Rifapentine without moxifloxacin was not shown to be noninferior to the control in either population (17.7% vs. 14.6% with an unfavorable outcome in the microbiologically eligible population; difference, 3.0 percentage points [95% CI, -0.6 to 6.6]; and 14.2% vs. 9.6% in the assessable population; difference, 4.4 percentage points [95% CI, 1.2 to 7.7]). Adverse events of grade 3 or higher occurred during the on-treatment period in 19.3% of participants in the control group, 18.8% in the rifapentine-moxifloxacin group, and 14.3% in the rifapentine group.

CONCLUSIONS

The efficacy of a 4-month rifapentine-based regimen containing moxifloxacin was noninferior to the standard 6-month regimen in the treatment of tuberculosis. (Funded by the Centers for Disease Control and Prevention and others; Study 31/A5349 ClinicalTrials.gov number, NCT02410772.).

Occurrence and characterization of Escherichia coli ST410 co-harbouring blaNDM-5, blaCMY-42 and blaTEM-190 in a dog from the UK

BACKGROUND/OBJECTIVES

Carbapenemase-producing Enterobacteriaceae (CPE) are a public health threat, and have been found in humans, animals and the environment. Carbapenems are not authorized for use in EU or UK companion animals, and the prevalence of carbapenem-resistant Gram-negative bacilli (CRGNB) in this population is unknown.

METHODS

We investigated CRGNB isolated from animal specimens received by one diagnostic laboratory from 34 UK veterinary practices (September 2015-December 2016). Any Gram-negative isolates from clinical specimens showing reduced susceptibility to fluoroquinolones and/or aminoglycosides and/or cephalosporins were investigated phenotypically and genotypically for carbapenemases. A complete genome assembly (Illumina/Nanopore) was generated for the single isolate identified to investigate the genetic context for carbapenem resistance.

RESULTS

One ST410 Escherichia coli isolate [(CARB35); 1/191, 0.5%], cultured from a wound in a springer spaniel, harboured a known carbapenem resistance gene (blaNDM-5). The gene was located in the chromosome on an integrated 100 kb IncF plasmid, also harbouring other drug resistance genes (mrx, sul1, ant1 and dfrA). The isolate also contained blaCMY-42 and blaTEM-190 on two separate plasmids (IncI1 and IncFII, respectively) that showed homology with other publicly available plasmid sequences from Italy and Myanmar.

CONCLUSIONS

Even though the use of carbapenems in companion animals is restricted, the concurrent presence of blaCMY-42 and other antimicrobial resistance genes could lead to co-selection of carbapenemase genes in this population. Further studies investigating the selection and flow of plasmids carrying important resistance genes amongst humans and companion animals are needed.

Inflammatory phenotyping predicts clinical outcome in COVID-19

Background

The COVID-19 pandemic has led to more than 760,000 deaths worldwide (correct as of 16th August 2020). Studies suggest a hyperinflammatory response is a major cause of disease severity and death. Identitfying COVID-19 patients with hyperinflammation may identify subgroups who could benefit from targeted immunomodulatory treatments. Analysis of cytokine levels at the point of diagnosis of SARS-CoV-2 infection can identify patients at risk of deterioration.

Methods

We used a multiplex cytokine assay to measure serum IL-6, IL-8, TNF, IL-1β, GM-CSF, IL-10, IL-33 and IFN-γ in 100 hospitalised patients with confirmed COVID-19 at admission to University Hospital Southampton (UK). Demographic, clinical and outcome data were collected for analysis.

Results

Age > 70 years was the strongest predictor of death (OR 28, 95% CI 5.94, 139.45). IL-6, IL-8, TNF, IL-1β and IL-33 were significantly associated with adverse outcome. Clinical parameters were predictive of poor outcome (AUROC 0.71), addition of a combined cytokine panel significantly improved the predictability (AUROC 0.85). In those ≤70 years, IL-33 and TNF were predictive of poor outcome (AUROC 0.83 and 0.84), addition of a combined cytokine panel demonstrated greater predictability of poor outcome than clinical parameters alone (AUROC 0.92 vs 0.77).

Conclusions

A combined cytokine panel improves the accuracy of the predictive value for adverse outcome beyond standard clinical data alone. Identification of specific cytokines may help to stratify patients towards trials of specific immunomodulatory treatments to improve outcomes in COVID-19.

Effects of motion and audio-visual redundancy on upright and inverted face and feature preferences in 4-13-month old pre- and full-term NICU graduates

NICU infants are reported to have diminished social orientation and increased risk of socio-communicative disorders. In this eye tracking study, we used a preference for upright compared to inverted faces as a gauge of social interest in high medical risk full- and pre-term NICU infants. We examined the effects of facial motion and audio-visual redundancy on face and eye/mouth preferences across the first year. Upright and inverted baby faces were simultaneously presented in a paired-preference paradigm with motion and synchronized vocalization varied. NICU risk factors including birth weight, sex, and degree of CNS injury were examined. Overall, infants preferred the more socially salient upright faces, making this the first report, to our knowledge, of an upright compared to inverted face preference among high medical risk NICU infants. Infants with abnormalities on cranial ultrasound displayed lower social interest, i.e. less of a preferential interest in upright faces, when viewing static faces. However, motion selectively increased their upright face looking time to a level equal that of infants in other CNS injury groups. We also observed an age-related sex effect suggesting higher risk in NICU males. Females increased their attention to the mouth in upright faces across the first year, especially between 7-10 months, but males did not. Although vocalization increased diffuse attention toward the screen, contrary to our predictions, there was no evidence that the audio-visual redundancy embodied in a vocalizing face focused additional attention on upright faces or mouths. This unexpected result may suggest a vulnerability in response to talking faces among NICU infants that could potentially affect later verbal and socio-communicative development.

Genomic dynamics of species and mobile genetic elements in a prolonged blaIMP-4-associated carbapenemase outbreak in an Australian hospital

BACKGROUND

Hospital outbreaks of carbapenemase-producing organisms, such as blaIMP-4-containing organisms, are an increasing threat to patient safety.

OBJECTIVES

To investigate the genomic dynamics of a 10 year (2006-15) outbreak of blaIMP-4-containing organisms in a burns unit in a hospital in Sydney, Australia.

METHODS

All carbapenem-non-susceptible or MDR clinical isolates (2006-15) and a random selection of equivalent or ESBL-producing environmental isolates (2012-15) were sequenced [short-read (Illumina), long-read (Oxford Nanopore Technology)]. Sequence data were used to assess genetic relatedness of isolates (Mash; mapping and recombination-adjusted phylogenies), perform in silico typing (MLST, resistance genes and plasmid replicons) and reconstruct a subset of blaIMP plasmids for comparative plasmid genomics.

RESULTS

A total of 46/58 clinical and 67/96 environmental isolates contained blaIMP-4. All blaIMP-4-positive organisms contained five or more other resistance genes. Enterobacter cloacae was the predominant organism, with 12 other species mainly found in either the environment or patients, some persisting despite several cleaning methods. On phylogenetic analysis there were three genetic clusters of E. cloacae containing both clinical and environmental isolates, and an additional four clusters restricted to either reservoir. blaIMP-4 was mostly found as part of a cassette array (blaIMP-4-qacG2-aacA4-catB3) in a class 1 integron within a previously described IncM2 plasmid (pEl1573), with almost complete conservation of this cassette across the species over the 10 years. Several other plasmids were also implicated, including an IncF plasmid backbone not previously widely described in association with blaIMP-4.

CONCLUSIONS

Genetic backgrounds disseminating blaIMP-4 can persist, diversify and evolve amongst both human and environmental reservoirs during a prolonged outbreak despite intensive prevention efforts.

Illumina short-read and MinION long-read WGS to characterize the molecular epidemiology of an NDM-1 Serratia marcescens outbreak in Romania

Background and Objectives

Serratia marcescens is an emerging nosocomial pathogen, and the carbapenemase bla_NDM has been reported in several surveys in Romania. We aimed to investigate the molecular epidemiology of S. marcescens in two Romanian hospitals over 2010–15, including a neonatal NDM-1 S. marcescens outbreak.

Methods

Isolates were sequenced using Illumina technology together with carbapenem-non-susceptible NDM-1-positive and NDM-1-negative Klebsiella pneumoniae and Enterobacter cloacae to provide genomic context. A subset was sequenced with MinION to fully resolve NDM-1 plasmid structures. Resistance genes, plasmid replicons and ISs were identified in silico for all isolates; an annotated phylogeny was reconstructed for S. marcescens. Fully resolved study NDM-1 plasmid sequences were compared with the most closely related publicly available NDM-1 plasmid reference.

Results

44/45 isolates were successfully sequenced (S. marcescens, n = 33; K. pneumoniae, n = 7; E. cloacae, n = 4); 10 with MinION. The S. marcescens phylogeny demonstrated several discrete clusters of NDM-1-positive and -negative isolates. All NDM-1-positive isolates across species harboured a pKOX_NDM1-like plasmid; more detailed comparisons of the plasmid structures demonstrated a number of differences, but highlighted the largely conserved plasmid backbones across species and hospital sites.

Conclusions

The molecular epidemiology is most consistent with the importation of a pKOX_NDM1-like plasmid into Romania and its dissemination amongst K. pneumoniae/E. cloacae and subsequently S. marcescens across hospitals. The data suggested multiple acquisitions of this plasmid by S. marcescens in the two hospitals studied; transmission events within centres, including a large outbreak on the Targu Mures neonatal unit; and sharing of the pKOX_NDM1-like plasmid between species within outbreaks.

Genomic epidemiology of global Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli

The dissemination of carbapenem resistance in Escherichia coli has major implications for the management of common infections. bla _KPC, encoding a transmissible carbapenemase (KPC), has historically largely been associated with Klebsiella pneumoniae, a predominant plasmid (pKpQIL), and a specific transposable element (Tn4401, ~10 kb). Here we characterize the genetic features of bla _KPC emergence in global E. coli, 2008-2013, using both long- and short-read whole-genome sequencing. Amongst 43/45 successfully sequenced bla _KPC-E. coli strains, we identified substantial strain diversity (n = 21 sequence types, 18% of annotated genes in the core genome); substantial plasmid diversity (≥9 replicon types); and substantial bla _KPC-associated, mobile genetic element (MGE) diversity (50% not within complete Tn4401 elements). We also found evidence of inter-species, regional and international plasmid spread. In several cases bla _KPC was found on high copy number, small Col-like plasmids, previously associated with horizontal transmission of resistance genes in the absence of antimicrobial selection pressures. E. coli is a common human pathogen, but also a commensal in multiple environmental and animal reservoirs, and easily transmissible. The association of bla _KPC with a range of MGEs previously linked to the successful spread of widely endemic resistance mechanisms (e.g. bla _TEM, bla _CTX-M) suggests that it may become similarly prevalent.

18-fluorodeoxyglucose positron emission tomography in the early diagnostic workup of differentiated thyroid cancer patients with a negative post-therapeutic iodine scan and detectable thyroglobulin

BACKGROUND

Surgery and high-dose radioactive iodine ((131)I) treatment are the cornerstones in the treatment of differentiated thyroid cancer. Patients without (131)I uptake on the post-therapeutic whole body scan (WBS), but with detectable thyroglobulin (Tg) during thyroxine withdrawal (Tg-off), are evaluated with an 18-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) for tumor localization within three months. The yield of (18)F-FDG-PET imaging and clinical usefulness of a Tg-off cutoff value to predict a positive scan were assessed.

METHODS

From 2002 to 2011, 52 patients with a negative WBS and concurrent detectable Tg-off were evaluated. Thirty-five PET scans were performed during initial treatment, 17 after recurrent disease. Thirty-two patients were on substitution therapy, 17 were evaluated with endogenous thyrotropin elevation, and 3 after recombinant human thyrotropin stimulation. To determine the Tg-off cutoff value, a receiver operating characteristic curve was used.

RESULTS

Nine (17%) (18)F-FDG-PET scans were true positive, 3 (6%) false positive, 36 (69%) true negative, and 4 (8%) false negative (sensitivity 69%, specificity 92%). In 13%, a true-positive scan resulted in a change in the clinical management. The area under the receiver operating characteristic curve is 0.82 [CI 0.64-0.99] (p<0.01), and the Tg-off cutoff value is 38.00 ng/mL (sensitivity 67%, specificity 95%). Ninety percent of (18)F-FDG-PET true-positive patients had a Tg-off >2.00 ng/mL.

CONCLUSIONS

An (18)F-FDG-PET within three months after a negative WBS with detectable Tg-off showed additional tumor localization in 17% of the patients, leading to a change in clinical management in 13%. A clinically useful Tg-off cutoff value was not found, but 90% of positive (18)F-FDG-PET scans occurred in patients with a Tg-off >2.00 ng/mL.

Neonatal brainstem function and 4-month arousal-modulated attention are jointly associated with autism

The authors evaluated the contribution of initially abnormal neonatal auditory brainstem responses (ABRs) and 4-month arousal-modulated attention visual preference to later autism spectrum disorder (ASD) behaviors in neonatal intensive care unit (NICU) graduates. A longitudinal study design was used to compare NICU graduates with normal ABRs (n = 28) to those with initially abnormal ABRs (n = 46) that later resolved. At 4 months postterm age, visual preference (measured after feeding) for a random check pattern flashing at 1, 3, or 8 Hz and gestational age (GA) served as additional predictors. Outcome measures were PDD Behavior Inventory (PDDBI) scores at 3.4 years (standard deviation = 1.2), and developmental quotients (DQ) obtained around the same age with the Griffiths Mental Development Scales (GMDS). Preferences for higher rates of stimulation at 4 months were highly correlated with PDDBI scores (all P-values < 0.01) and the GMDS Hearing and Speech DQ, but only in those with initially abnormal ABRs. Effects were strongest for a PDDBI social competence measure most associated with a diagnosis of autism. For those with abnormal ABRs, increases in preference for higher rates of stimulation as infants were linked to nonlinear increases in severity of ASD at 3 years and to an ASD diagnosis. Abnormal ABRs were associated with later reports of repetitive and ritualistic behaviors irrespective of 4-month preference for stimulation. The joint occurrence of initially abnormal neonatal ABRs and preference for more stimulation at 4 months, both indices of early brainstem dysfunction, may be a marker for the development of autism in this cohort.

Comparative genomics to bridge Vicia faba with model and closely-related legume species: stability of QTLs for flowering and yield-related traits

This study presents the development of an enhanced map in faba bean. The map contains 258 loci, mostly gene-based markers, organized in 16 linkage groups that expand 1,875 cM, with an average inter-marker distance of 7.26 cM. The combination of EST-derived markers with a number of markers physically located or previously ascribed to chromosomes by trisomic segregation, allowed the allocation of eight linkage groups (229 markers), to specific chromosomes. Moreover, this approach provided anchor points to establish a global homology among the faba bean chromosomes and those of closely-related legumes species. The map was used to identify and validate, for the first time, QTLs controlling five flowering and reproductive traits: days to flowering, flowering length, pod length, number of seeds per pod and number of ovules per pod. Twelve QTLs stable in the 2 years of evaluation were identified in chromosomes II, V and VI. Comparative mapping suggested the conservation of one of the faba bean genomic regions controlling the character days to flowering in other five legume species (Medicago, Lotus, pea, lupine, chickpea). Additional syntenic co-localizations of QTLs controlling pod length and number of seeds per pod between faba bean and Lotus japonicus are likely. The new genetic map opens the way for further translational studies between faba bean and related legume species, and provides an efficient tool for breeding applications such as QTL analysis and marker-assisted selection.

Auditory brainstem evoked responses in newborns with Down syndrome

Auditory brainstem evoked responses (ABRs) were compared in 15 newborns with Down syndrome and 15 sex-, age-, and weight-matched control newborns. Participants had normal ABRs based upon values specific to 32- to 42-weeks postconceptional age. Although Wave III and Wave V component latencies and the Wave I-III interpeak latency (IPL) were shorter in ABRs of infants with Down syndrome, the Wave III-V IPL was not, pointing to anomalies in the lower rather than upper brainstem auditory pathways. Shorter Down syndrome ABR latencies have been reported at many ages. Extending these findings to newborns suggests that the underlying basis for this develops prenatally. ABR patterns in infants with Down syndrome were similar to reports for intrauterine growth restricted newborns.

The diagnostic value of 124I-PET in patients with differentiated thyroid cancer

BACKGROUND

The purpose of this prospective study was to evaluate the clinical diagnostic value of iodine-124 (124I)-positron emission tomography (PET) in patients with advanced differentiated thyroid carcinoma (DTC) and to compare the 124I-PET imaging results with the 131I whole-body scan (WBS).

MATERIALS AND METHODS

Twenty patients with histologically proven advanced DTC (including T4, extra-nodal tumour growth, or distant metastases) underwent diagnostic 131I-WBS, 124I-PET scan, and post-treatment 131I-WBS 4 months after ablation. The findings on the 124I-PET were compared with the findings on the diagnostic and post-therapeutic 131I-WBS and were also correlated with radiologic and/or cytological investigations.

RESULTS

124 I-PET vs diagnostic 131 I-WBS. Eleven patients showed uptake on the 124I-PET. Only 3 of these 11 patients also showed uptake on the diagnostic 131I scan, but the uptake was more clearly visible and the abnormalities were more extensive on the 124I-PET. 124 I-PET vs post-treatment 131 I-WBS. Eleven patients showed uptake on the 124I-PET, which was also visible on the post-treatment scan in nine patients; in the other two patients, no uptake was observed on the post-treatment scan and no anatomical localisation could be confirmed. Two patients showed only uptake on the post-treatment scan without uptake on the 124I-PET: in one, the uptake was confirmed by MRI, and in the other, no anatomical localisation was found. In seven patients, no uptake was observed on both the scans.

CONCLUSION

124I-PET proved to be a superior diagnostic tool as compared to low-dose diagnostic 131I scans and adequately predicted findings on subsequent high-dose post-treatment 131I scans.

The follow-up of patients with differentiated thyroid cancer and undetectable thyroglobulin (Tg) and Tg antibodies during ablation

OBJECTIVE

This retrospective study describes the role of serum thyroglobulin (Tg) in relation to tumor characteristics in the prediction of persistent/recurrent disease in patients with differentiated thyroid cancer (DTC) with negative Tg at the time of ablation.

DESIGN

Between 1989 and 2006, 94 out of 346 (27%) patients with DTC had undetectable Tg at the time of 131I ablation and were included in this evaluation. The group of 94 patients consisted of 15 males and 79 females in the age range of 16-89 years with a median follow-up of 8 years (range 1-17). All medical records and follow-up parameters of the 94 patients were evaluated for the occurrence of persistent/recurrent disease. In patients with persistent/recurrent disease hematoxylin-eosin-stained slides of the primary tumors and/or metastatic lesions were also reviewed for histological features including immunostains for Tg.

RESULTS

During follow-up, 8 out of 94 (8.5%) patients showed persistent/recurrent disease: in the course of the disease two patients showed Tg positivity, three showed Tg antibody (TgAb) positivity, and the other three showed persistently undetectable Tg and TgAb. Patients who developed Tg and/or TgAb positivity during follow-up had a significantly shorter disease-free survival period when compared with patients with persistently undetectable Tg and TgAb (P<0.006). Histological features were not able to predict the recurrent status.

CONCLUSIONS

Follow-up of Tg and TgAb in patients with initially negative Tg and TgAb is useful since a number of patients had shown detectable Tg or TgAb during follow-up indicative for persistent/recurrent disease. Tg and TgAb negativity at the time of ablation is not a predictive determinant for future recurrent status.

Detection of bone metastases in thyroid cancer patients: bone scintigraphy or 18F-FDG PET?

BACKGROUND

Similar to the situation in other tumour types, it is currently unclear whether fluorodeoxyglucose (FDG) positron emission tomography (PET) is adequate in the detection of bone metastases of thyroid cancer. The purpose of this retrospective study was to evaluate the performance of bone scans in comparison with FDG PET in the detection of bone metastases in patients with differentiated thyroid cancer (DTC).

MATERIALS AND METHODS

Twenty-four patients had undergone both FDG PET and bone scans within 6 months because of suspected bone metastases. All scans were re-evaluated using all available additional imaging and clinical data for verification. Scan findings were scored as positive, negative or doubtful.

RESULTS

Bone metastases were present in eight of 24 (33%) patients. Only bone scintigraphy but not FDG PET suggested the presence of bone metastases in three patients, all confirmed with magnetic resonance imaging (MRI)/X-ray. Five patients were identified with bone metastases on both bone scan and FDG PET, which was confirmed by computed tomography (CT)/MRI/X-ray in four. Five patients had doubtful findings on bone scans whereas FDG PET scans were negative. MRI showed degenerative disorders in two of five and was normal in two. Eleven patients had both a negative bone scan and FDG PET scan.

CONCLUSION

In three of eight (38%) thyroid cancer patients bone metastases were only identified on bone scans. Therefore, bone scans are still valuable in detecting bone metastases in patients with DTC and can not be replaced by FDG PET.

Identification of QTL for reaction to three races of Colletotrichum trifolii and further analysis of inheritance of resistance in autotetraploid lucerne

Anthracnose, caused by Colletotrichum trifolii, is one of the most serious diseases of lucerne worldwide. The disease is managed through deployment of resistant cultivars, but new pathotypes present a challenge to the successful implementation of this strategy. This paper reports the genetic map locations of quantitative trait loci (QTL) for reaction to races 1, 2 and 4 of C. trifolii in a single autotetraploid lucerne clone, designated W126 from the Australian cv. Trifecta. Resistance was mapped in a backcross population of 145 individuals, and reaction was assessed both by spray and injection inoculation of stems. Resistance to injection inoculation with races 1 and 4 was incompletely dominant and closely linked (phenotypic markers 2.2 cM apart); these resistances mapped to a linkage group homologous to Medicago truncatula linkage group 8. When the spray inoculation data were subjected to QTL analysis, the strongest QTL for resistance was located on linkage group 8; six QTL were identified for race 1 and four for race 4. Resistance to race 2 was incompletely recessive; four QTL were identified and these include one QTL on linkage group 4 that was also identified for race 1. Modelling of the interactions between individual QTL and marker effects allowed a total of 52-63% of the phenotypic variation to be described for each of the different races. These markers will have value in breeding lucerne, carrying multiple sources of resistance to the three known races of C. trifolii.

Identification of QTL for resistance and susceptibility to Stagonospora meliloti in autotetraploid lucerne

In eastern Australia and California, USA, one of the major lethal fungal diseases of lucerne (Medicago sativa) is Stagonospora root and crown rot, caused by Stagonospora meliloti. Quantitative trait loci (QTL) involved in resistance and susceptibility to S. meliloti were identified in an autotetraploid lucerne backcross population of 145 individuals. Using regression analysis and interval mapping, we detected one region each on linkage groups 2, 6 and 7 that were consistently associated with disease reaction to S. meliloti in two separate experiments. The largest QTL on linkage group 7, which is associated with resistance to S. meliloti, contributed up to 17% of the phenotypic variation. The QTL located on linkage group 2, which is potentially a resistance allele in repulsion to the markers for susceptibility to S. meliloti, contributed up to 8% of the phenotypic variation. The QTL located on linkage group 6, which is associated with susceptibility to S. meliloti, contributed up to 16% of the phenotypic variation. A further two unlinked markers contributed 5 and 8% of the phenotypic variation, and were detected in only one experiment. A total of 517 simple sequence repeat (SSR) markers from Medicago truncatula were screened on the parents of the mapping population. Only 27 (6%) SSR markers were polymorphic and could be incorporated into the autotetraploid map of M. sativa. This allowed alignment of our M. sativa linkage map with published M. truncatula maps. The markers linked to the QTL we have reported will be useful for marker assisted selection for partial resistance to S. meliloti in lucerne.

Implications of mediastinal uptake of131I with regard to surgery in patients with differentiated thyroid carcinoma

BACKGROUND

Findings of mediastinal uptake of 131I after surgical treatment for differentiated thyroid carcinoma (DTC) are common, especially in young patients. Given the frequency of false-positive findings, a protocol for diagnostic and therapeutic strategies would be useful. With the goal of accurately selecting management strategies, the authors analyzed their data and data found elsewhere in the literature for correlations with the incidence of mediastinal 131I uptake and with treatment for patients exhibiting such 131I uptake.

METHODS

All patients with DTC who were treated between 1978 and 2000 at Groningen University Hospital (Groningen, The Netherlands) and who received adjuvant 131I ablation therapy were included in the current analysis, which involved retrospective review of all relevant data.

RESULTS

Five hundred four patients with DTC initially underwent total thyroidectomy, with additional 131I ablation performed for 489 of these patients. In 48 of 489 patients (9.8%), 131I uptake was seen in the mediastinum on a posttreatment scan. Analysis of those 48 patients and of cases in the literature demonstrated that serum thyroglobulin levels, risk status, and the presence of thymus on radiologic images were important in the surgical decision-making process.

CONCLUSIONS

Mediastinal uptake of 131I on posttreatment scans was found in approximately 10% of patients after total thyroidectomy for DTC. Based on the current data and the data presented in the literature, the authors developed a flow chart for determining appropriate treatment strategies, which included mediastinal dissection for high-risk patients and for patients with serum thyroglobulin levels > 10 ng/mL.

Mapping the mating type locus of Ascochyta rabiei, the causal agent of ascochyta blight of chickpea

SUMMARY A genome linkage map was developed for Ascochyta rabiei (Pass.) Labrousse, (teleomorph) Didymella rabiei (Kovachevski), an important pathogen causing ascochyta blight in chickpea (Cicer arietinum L.). The map was constructed using 96 progeny generated from a single pseudothecium produced from a cross between a USA MAT-2 isolate and an Australian MAT-1 isolate. The map comprised 126 molecular markers of which 69 were random amplified polymorphic DNA (RAPD) markers, 46 were amplified fragment length polymorphic (AFLP) markers, 10 were sequence-tagged microsatellite site (STMS) markers, and one was a sequence characterized amplified region (SCAR) marker. Eighteen large and 10 small linkage groups (LG) were characterized and the mating-type locus was mapped on to LGd. The map spanned 1271 cM with an average spacing between markers of 15.1 cM. The SCAR marker, specific for mating type 2, was designed to amplify a region of the MAT locus and was used to identify the mating type of A. rabiei isolates. One AFLP marker, derived from the MAT-1 parent, was closely linked to the mating-type locus (9.6 cM). The linkage map provides a framework for the future identification of the locations of other important traits such as virulence/avirulence and fungicide resistance. Findings from this study suggest that the MAT-2 isolates of D. rabiei should be renamed to MAT-1 isolates because the alpha-box, specific for MAT-1 from other ascomycetes, was amplified from A. rabiei MAT-2 isolates.