Population Dynamics and Genetics of Plant Disease: A Case Study of Anther-Smut Disease

This is the publisher's version, also available electronically from http://www.jstor.org/stable/info/2265569A model by Levin and Udovic (1977) emphasizes the need for integration of studies of the numerical abundances and genetic composition of host and pathogen species. We use their conceptual framework to summarize our collaborative research on the ecological genetics of the anther-smut disease of Silene alba caused by the fungus Ustilago violacea. Our theoretical investigations have revealed the importance of the rate and mode of disease transmission on the likelihood of coexistence between host and pathogen. Our empirical studies have quantified patterns of disease spread on local and regional spatial scales and have shown that host genotypes differ greatly in resistance. Comparable genetic variation in pathogen virulence has not yet been demonstrated. The genetic composition of host populations alters numerical dynamics in experimental populations: disease declines in resistant populations, while host and pathogen appear to coexist in susceptible populations. Ecological outcomes also may be affected by the negative relationship between disease incidence and host flowering time, which may constitute a "cost" to resistance. We are currently expanding our work on the ecology and genetics of metapopulation dynamics of host and pathogen

The Distribution of Mating-Type Bias in Natural Populations of the Anther-Smut Ustilago violacea on Silene alba in Virginia

This is the publisher's version, also available electronically from http://www.jstor.org/stable/info/3761395.Complete individual-wide mating-type bias (retrieval of sporidia of only one mating type from germinated teliospores of one fungal individual) was observed to be a common and widespread feature of the anther-smut fungus, Ustilago violacea, collected from natural populations of its host, Silene alba. The bias was usually to mating type A1, but the frequency of bias and its spatial distribution varied from region to region. Populations with high frequencies of bias still showed high rates of disease transmission. Crosses between A1 mating type sporidial lines from completely biased individuals and A2 mating types from unbiased individuals showed no bias in the progeny. During teliospore germination, biased individuals often showed conjugation among adjacent cells of the promycelium, suggesting that both mating types are present in the germinating teliospore but one mating type is unable to grow as free-living sporidia. The complete bias was most readily interpreted as evidence of "haploid lethals" linked to mating type that cause poor survival or growth of the sporidial stage. The results show that such "haploid lethals" may be a common occurrence in natural populations, and that fungal mating systems may vary considerably over short distances

Renal recovery after acute kidney injury

Acute kidney injury (AKI) is a frequent complication of critical illness and carries a significant risk of short-and long-term mortality, chronic kidney disease (CKD) and cardiovascular events. The degree of renal recovery from AKI may substantially affect these long-term endpoints. Therefore maximising recovery of renal function should be the goal of any AKI prevention and treatment strategy. Defining renal recovery is far from straightforward due in part to the limitations of the tests available to assess renal function. Here, we discuss common pitfalls in the evaluation of renal recovery and provide suggestions for improved assessment in the future. We review the epidemiology of renal recovery and of the association between AKI and the development of CKD. Finally, we stress the importance of post-discharge follow-up of AKI patients and make suggestions for its incorporation into clinical practice. Summary key points are that risk factors for non-recovery of AKI are age, CKD, comorbidity, higher severity of AKI and acute disease scores. Second, AKI and CKD are mutually related and seem to have a common denominator. Third, despite its limitations full recovery of AKI may best be defined as the absence of AKI criteria, and partial recovery as a fall in AKI stage. Fourth, after an episode of AKI, serial follow-up measurements of serum creatinine and proteinuria are warranted to diagnose renal impairment and prevent further progression. Measures to promote recovery are similar to those preventing renal harm. Specific interventions promoting repair are still experimental.Peer reviewe

Magnesium lactate in the treatment of Gitelman syndrome: patient-reported outcomes.

BACKGROUND: Gitelman syndrome (GS) is a rare recessively inherited renal tubulopathy associated with renal potassium (K) and magnesium (Mg) loss. It requires lifelong K and Mg supplementation at high doses that are at best unpalatable and at worst, intolerable. In particular, gastrointestinal side effects often limit full therapeutic usage. METHODS: We report here the analysis of a cohort of 28 adult patients with genetically proven GS who attend our specialist tubular disorders clinic, in whom we initiated the use of a modified-release Mg preparation (slow-release Mg lactate) and who were surveyed by questionnaire. RESULTS: Twenty-five patients (89%) preferred the new treatment regimen. Of these 25, 17 (68%) regarded their symptom burden as improved and seven reported no worsening. Of the 25 who were not Mg-treatment naïve, 13 (59%) patients reported fewer side effects, 7 (32%) described them as the same and only 2 (9%) considered side effects to be worse. Five were able to increase their dose without ill-effect. Overall, biochemistry improved in 91% of the 23 patients switched from therapy with other preparations who chose to continue the modified-release Mg preparation. Eleven (48%) improved both their Mg and K mean levels, 3 (13%) improved Mg levels only and in 7 cases (30%), K levels alone rose. CONCLUSIONS: Patient-reported and biochemical outcomes using modified-release Mg supplements were very favourable, and patient choice should play a large part in choosing Mg supplements with GS patients.This work was supported by the Wellcome Trust and the NIHR Cambridge Biomedical Research Centre, and contains data that were presented in abstract form at ASN Kidney week 2014.This is the final version of the article. It first appeared from Oxford University Press via https://doi.org/10.1093/ndt/gfw01

Initial microbial spectrum in severe secondary peritonitis and relevance for treatment

This study aims to determine whether abdominal microbial profiles in early severe secondary peritonitis are associated with ongoing infection or death. The study is performed within a randomized study comparing two surgical treatment strategies in patients with severe secondary peritonitis (n = 229). The microbial profiles of cultures retrieved from initial emergency laparotomy were tested with logistic regression analysis for association with ‘ongoing infection needing relaparotomy’ and in-hospital death. No microbial profile or the presence of yeast or Pseudomonas spp. was related to the risk of ongoing infection needing relaparotomy. Resistance to empiric therapy for gram positive cocci and coliforms was moderately associated with ongoing abdominal infection (OR 3.43 95%CI 0.95–12.38 and OR 7.61, 95%CI 0.75–76.94). Presence of only gram positive cocci, predominantly Enterococcus spp, was borderline independently associated with in-hospital death (OR 3.69, 95%CI 0.99–13.80). In secondary peritonitis microbial profiles do not predict ongoing abdominal infection after initial emergency laparotomy. However, the moderate association of ongoing infection with resistance to the empiric therapy compels to more attention for resistance when selecting empiric antibiotic coverage

Spontaneous perforation of the cystic duct in streptococcal toxic shock syndrome: a case report

Introduction: Streptococcal toxic shock syndrome is a complication of group A streptococcal infection, most often originating from the skin. The syndrome is characterized by fever, hypotension and multiple organ failure. Mortality rate may be as high as 80%. Case presentation: A 25-year-old man of Indian origin presented with abdominal complaints, rash and fever after an episode of pharyngitis. The patient was operated and a biliary peritonitis was found caused by perforation of the cystic duct in the absence of calculi. Cholecystectomy was performed, but after the operation, the patient's condition worsened and multi-organ failure developed. Group A streptococci were cultured in blood taken at admission and streptococcal toxic shock syndrome was diagnosed. Treatment consisted of antibiotics, corticosteroids, immunoglobulin and supportive treatment for haemodynamic, respiratory and renal failure. Conclusion: This is a patient with streptococcal toxic shock syndrome complicated by spontaneous perforation of the cystic duct. Spontaneous perforation of the cystic duct is a rare finding, most often reported in children and secondary to anatomic defects. We found only one similar adult case in the literature. Perforation may be due to microthrombosis and ischaemia, and so be a part of the multi-organ failure often found in streptococcal toxic shock syndrome

Mites Parasitic on Australasian and African Spiders Found in the Pet Trade; a Redescription of Ljunghia pulleinei Womersley

Parasitic mites associated with spiders are spreading world-wide through the trade in tarantulas and other pet species. Ljunghia pulleinei Womersley, a mesostigmatic laelapid mite originally found in association with the mygalomorph spider Selenocosmia stirlingi Hogg (Theraphosidae) in Australia, is redescribed and illustrated on the basis of specimens from the African theraphosid spider Pterinochilus chordatus (Gersta¨cker) kept in captivity in the British Isles (Wales). The mite is known from older original descriptions of Womersley in 1956; the subsequent redescription of Domrow in 1975 seems to be questionable in conspecificity of treated specimens with the type material. Some inconsistencies in both descriptions are recognised here as intraspecific variability of the studied specimens. The genus Arachnyssus Ma, with species A. guangxiensis (type) and A. huwenae, is not considered to be a valid genus, and is included in synonymy with Ljunghia Oudemans. A new key to world species of the genus Ljunghia is provided

Renal replacement therapy in acute kidney injury: controversy and consensus

Renal replacement therapies (RRTs) represent a cornerstone in the management of severe acute kidney injury. This area of intensive care and nephrology has undergone significant improvement and evolution in recent years. Continuous RRTs have been a major focus of new technological and treatment strategies. RRT is being used increasingly in the intensive care unit, not only for renal indications but also for other organ-supportive strategies. Several aspects related to RRT are now well established, but others remain controversial. In this review, we review the available RRT modalities, covering technical and clinical aspects. We discuss several controversial issues, provide some practical recommendations, and where possible suggest a research agenda for the future

Habitat and Host Indicate Lineage Identity in Colletotrichum gloeosporioides s.l. from Wild and Agricultural Landscapes in North America

Understanding the factors that drive the evolution of pathogenic fungi is central to revealing the mechanisms of virulence and host preference, as well as developing effective disease control measures. Prerequisite to these pursuits is the accurate delimitation of species boundaries. Colletotrichum gloeosporioides s.l. is a species complex of plant pathogens and endophytic fungi for which reliable species recognition has only recently become possible through a multi-locus phylogenetic approach. By adopting an intensive regional sampling strategy encompassing multiple hosts within and beyond agricultural zones associated with cranberry (Vaccinium macrocarpon Aiton), we have integrated North America strains of Colletotrichum gloeosporioides s.l. from these habitats into a broader phylogenetic framework. We delimit species on the basis of genealogical concordance phylogenetic species recognition (GCPSR) and quantitatively assess the monophyly of delimited species at each of four nuclear loci and in the combined data set with the genealogical sorting index (gsi). Our analysis resolved two principal lineages within the species complex. Strains isolated from cranberry and sympatric host plants are distributed across both of these lineages and belong to seven distinct species or terminal clades. Strains isolated from V. macrocarpon in commercial cranberry beds belong to four species, three of which are described here as new. Another species, C. rhexiae Ellis & Everh., is epitypified. Intensive regional sampling has revealed a combination of factors, including the host species from which a strain has been isolated, the host organ of origin, and the habitat of the host species, as useful indicators of species identity in the sampled regions. We have identified three broadly distributed temperate species, C. fructivorum, C. rhexiae, and C. nupharicola, that could be useful for understanding the microevolutionary forces that may lead to species divergence in this important complex of endophytes and plant pathogens