A Novel Small Acid Soluble Protein Variant Is Important for Spore Resistance of Most Clostridium perfringens Food Poisoning Isolates

Clostridium perfringens is a major cause of food poisoning (FP) in developed countries. C. perfringens isolates usually induce the gastrointestinal symptoms of this FP by producing an enterotoxin that is encoded by a chromosomal (cpe) gene. Those typical FP strains also produce spores that are extremely resistant to food preservation approaches such as heating and chemical preservatives. This resistance favors their survival and subsequent germination in improperly cooked, prepared, or stored foods. The current study identified a novel α/β-type small acid soluble protein, now named Ssp4, and showed that sporulating cultures of FP isolates producing resistant spores consistently express a variant Ssp4 with an Asp substitution at residue 36. In contrast, Gly was detected at Ssp4 residue 36 in C. perfringens strains producing sensitive spores. Studies with isogenic mutants and complementing strains demonstrated the importance of the Asp 36 Ssp4 variant for the exceptional heat and sodium nitrite resistance of spores made by most FP strains carrying a chromosomal cpe gene. Electrophoretic mobility shift assays and DNA binding studies showed that Ssp4 variants with an Asp at residue 36 bind more efficiently and tightly to DNA than do Ssp4 variants with Gly at residue 36. Besides suggesting one possible mechanistic explanation for the highly resistant spore phenotype of most FP strains carrying a chromosomal cpe gene, these findings may facilitate eventual development of targeted strategies to increase killing of the resistant spores in foods. They also provide the first indication that SASP variants can be important contributors to intra-species (and perhaps inter-species) variations in bacterial spore resistance phenotypes. Finally, Ssp4 may contribute to spore resistance properties throughout the genus Clostridium since ssp4 genes also exist in the genomes of other clostridial species

The Mating-Type Chromosome in the Filamentous Ascomycete Neurospora tetrasperma Represents a Model for Early Evolution of Sex Chromosomes

We combined gene divergence data, classical genetics, and phylogenetics to study the evolution of the mating-type chromosome in the filamentous ascomycete Neurospora tetrasperma. In this species, a large non-recombining region of the mating-type chromosome is associated with a unique fungal life cycle where self-fertility is enforced by maintenance of a constant state of heterokaryosis. Sequence divergence between alleles of 35 genes from the two single mating-type component strains (i.e. the homokaryotic mat A or mat a-strains), derived from one N. tetrasperma heterokaryon (mat A+mat a), was analyzed. By this approach we were able to identify the boundaries and size of the non-recombining region, and reveal insight into the history of recombination cessation. The non-recombining region covers almost 7 Mbp, over 75% of the chromosome, and we hypothesize that the evolution of the mating-type chromosome in this lineage involved two successive events. The first event was contemporaneous with the split of N. tetrasperma from a common ancestor with its outcrossing relative N. crassa and suppressed recombination over at least 6.6 Mbp, and the second was confined to a smaller region in which recombination ceased more recently. In spite of the early origin of the first “evolutionary stratum”, genealogies of five genes from strains belonging to an additional N. tetrasperma lineage indicate independent initiations of suppressed recombination in different phylogenetic lineages. This study highlights the shared features between the sex chromosomes found in the animal and plant kingdoms and the fungal mating-type chromosome, despite fungi having no separate sexes. As is often found in sex chromosomes of plants and animals, recombination suppression of the mating-type chromosome of N. tetrasperma involved more than one evolutionary event, covers the majority of the mating-type chromosome and is flanked by distal regions with obligate crossovers

Endoscopic resection of giant lipoma mimicking colonic neoplasm initially presenting with massive haemorrhage: a case report

Lipomas of the colon are benign tumors that rarely occur. Their size ranges from 2 mm to several cm. They are usually asymptomatic but occasionally they present with clinical manifestations depending on tumor size, localization and complications, which often lead to diagnostic difficulty. A 40-year-old man presented with massive rectal haemorrhage. During colonoscopy a giant polyp of over 50 mm in its bigger diameter, with a thick stalk of 2 cm, located in the transverse colon, was revealed. Endoscopic resection was performed with success. Histologic examination demonstrated a giant lipoma. In this report discussion over endoscopic resection of colonic lipomas mimicking neoplasms is also performed

Neurospora from natural populations: Population genomics insights into the Life history of a model microbial Eukaryote

The ascomycete filamentous fungus Neurospora crassa played a historic role in experimental biology and became a model system for genetic research. Stimulated by a systematic effort to collect wild strains initiated by Stanford geneticist David Perkins, the genus Neurospora has also become a basic model for the study of evolutionary processes, speciation, and population biology. In this chapter, we will first trace the history that brought Neurospora into the era of population genomics. We will then cover the major contributions of population genomic investigations using Neurospora to our understanding of microbial biogeography and speciation, and review recent work using population genomics and genome-wide association mapping that illustrates the unique potential of Neurospora as a model for identifying the genetic basis of (potentially adaptive) phenotypes in filamentous fungi. The advent of population genomics has contributed to firmly establish Neurospora as a complete model system and we hope our review will entice biologists to include Neurospora in their research

Successful side-viewing endoscopic hemoclipping for Dieulafoy-like lesion at the brim of a periampullary diverticulum

<p>Abstract</p> <p>Background</p> <p>Duodenal Dieulafoy's lesions are rare and only several cases were reported so far. Their characteristic appearance and location make it difficult to be diagnosed in the clinical practice. Massive bleeding often results from these lesions and can impede the accurate early treatment.</p> <p>Case presentation</p> <p>67 years old male patient suffered a fatal bleeding from Dieulafoy-like lesion located at the mouth of the periampullary diverticulum. Inintial endoscopic therapy and radiologic embolization failed to stop the bleeding, while direct observation and hemoclipping by the side viewing endoscopy successfully established correct diagnosis and permanent cure of the lesion.</p> <p>Conclusion</p> <p>Aggressive endoscopic examinations combined with the accurate endoscopic threatment should be adopted when Dieulafoy-like lesion is suspected as a possible cause of the proximal small bowel hemorrahge. Verification of the diagnosis and definitive treatment often needed repeated examination by side-viewing endoscope as well as stabilization of the patient.</p

Ultra-fast Microwave Synthesis of ZnO Nanowires and their Dynamic Response Toward Hydrogen Gas

Ultra-fast and large-quantity (grams) synthesis of one-dimensional ZnO nanowires has been carried out by a novel microwave-assisted method. High purity Zinc (Zn) metal was used as source material and placed on microwave absorber. The evaporation/oxidation process occurs under exposure to microwave in less than 100 s. Field effect scanning electron microscopy analysis reveals the formation of high aspect-ratio and high density ZnO nanowires with diameter ranging from 70 to 80 nm. Comprehensive structural analysis showed that these ZnO nanowires are single crystal in nature with excellent crystal quality. The gas sensor made of these ZnO nanowires exhibited excellent sensitivity, fast response, and good reproducibility. Furthermore, the method can be extended for the synthesis of other oxide nanowires that will be the building block of future nanoscale devices

Budd-Chiari Syndrome: Long term success via hepatic decompression using transjugular intrahepatic porto-systemic shunt

<p>Abstract</p> <p>Background</p> <p>Budd-Chiari syndrome (BCS) generally implies thrombosis of the hepatic veins and/or the intrahepatic or suprahepatic inferior vena cava. Treatment depends on the underlying cause, the anatomic location, the extent of the thrombotic process and the functional capacity of the liver. It can be divided into medical treatment including anticoagulation and thrombolysis, radiological procedures such as angioplasty and transjugular intrahepatic porto-systemic shunt (TIPS) and surgical interventions including orthotopic liver transplantation (OLT). Controlled trials or reports on larger cohorts are limited due to rare disease frequency. The aim of this study was to report our single centre long term results of patients with BCS receiving one of three treatment options i.e. medication only, TIPS or OLT on an individually based decision of our local expert group.</p> <p>Methods</p> <p>20 patients with acute, subacute or chronic BCS were treated between 1988 and 2008. Clinical records were analysed with respect to underlying disease, therapeutic interventions, complications and overall outcome.</p> <p>Results</p> <p>16 women and 4 men with a mean age of 34 ± 12 years (range: 14-60 years) at time of diagnosis were included. Myeloproliferative disorders or a plasmatic coagulopathy were identified as underlying disease in 13 patients, in the other patients the cause of BCS remained unclear. 12 patients presented with an acute BCS, 8 with a subacute or chronic disease. 13 patients underwent TIPS, 4 patients OLT as initial therapy, 2 patients required only symptomatic therapy, and one patient died from liver failure before any specific treatment could be initiated. Eleven of 13 TIPS patients required 2.5 ± 2.4 revisions (range: 0-8). One patient died from his underlying hematologic disease. The residual 12 patients still have stable liver function not requiring OLT. All 4 patients who underwent OLT as initial treatment, required re-OLT due to thrombembolic complications of the graft. Survival in the TIPS group was 92.3% and in the OLT group 75% during a median follow-up of 4 and 11.5 years, respectively.</p> <p>Conclusion</p> <p>Our results confirm the role of TIPS in the management of patients with acute, subacute and chronic BCS. The limited number of patients with OLT does not allow to draw a meaningful conclusion. However, the underlying disease may generate major complications, a reason why OLT should be limited to patients who cannot be managed by TIPS.</p

Evaluation of invasive and non-invasive methods for the diagnosis of Helicobacter pylori infection in symptomatic children and adolescents

CONTEXT: Multiple diagnostic methods are available for the detection of Helicobacter pylori infection, but at present no single one can be used as the gold standard. OBJECTIVE: The aim of this study was to evaluate the diagnostic accuracy of 3 invasive and 2 non-invasive methods for detection of Helicobacter pylori infection in symptomatic children and adolescents. DESIGN: Prospective cohort study SETTING: Peptic Disease outpatients service, Discipline of Pediatric Gastroenterology, Universidade Federal de São Paulo (UNIFESP) / Escola Paulista de Medicina. PATIENTS: Forty-seven patients who underwent endoscopy because of dyspeptic symptoms. DIAGNOSTIC METHODS: Endoscopy with gastric biopsies for 3 invasive (rapid urease test, histology and culture) and 2 non-invasive methods (a commercial ELISA serology and 13carbon urea breath test - isotope ratio mass spectrometry) for detection of Helicobacter pylori infection. MAIN MEASUREMENTS: Sensitivity, specificity, positive and negative predictive values of each method and agreement and disagreement rates between the methods. RESULTS: Forty-seven patients [mean age, 11y9mo (SD 2y10mo), 27 female and 20 male]; 62% of them were Helicobacter pylori-positive. All methods agreed in 61%, and were negative in 21% and positive in 40%. The greatest concordance between 2 methods occurred between the invasive methods: histology and rapid urease test (89.6%) and histology and culture (87.5%). The greatest sensitivity, considering Helicobacter pylori-positive cases, for any combination of 3 or more tests, was achieved by the rapid urease test (S=100%), followed by histology, serology and 13carbon-urea breath test (S=93.1%) and lastly by culture (S=79.3%). The highest specificity was obtained by histology (100%) and culture (100%), followed by the rapid urease test (84.2%), serology (78.9%) and 13carbon-urea breath test (78.9%). CONCLUSIONS: Our results suggest that among invasive methods, an association between the rapid urease test and histology constituted the best choice for the detection of Helicobacter pylori infection. If results of histology and the rapid urease test are different, serology may be recommended.CONTEXTO: Vários métodos diagnósticos estão disponíveis para a detecção da infecção por Helicobacter pylori (Hp), porém, até o presente momento, não há um teste que possa ser utilizado isoladamente como padrão-ouro. OBJETIVO: Avaliar a acurácia de três métodos invasivos e dois não-invasivos na detecção da infecção por Hp em crianças e adolescentes sintomáticos. TIPO DE ESTUDO: Estudo coorte prospectivo. LOCAL: Ambulatório de Doença Péptica, Disciplina de Gastroenterologia Pediátrica, Universidade Federal de São Paulo (UNIFESP) / Escola Paulista de Medicina. PACIENTES: 47 pacientes sintomáticos que realizaram exame endoscópico devido a sintomas dispépticos. MÉTODOS DIAGNÓSTICOS: Exame endoscópico com biopsias gástricas para três métodos invasivos (teste rápido da urease, histologia e cultura) e dois métodos não-invasivos (teste sorológico ELISA industrializado e teste respiratório com uréia marcada com Carbono13). VARIÁVEIS ESTUDADAS: Sensibilidade, especificidade, valor preditivo positivo e negativo de cada método e taxas de concordância e discordância entre os métodos. RESULTADOS: 47 pacientes [idade média de 11a9m (DP 2a10m), 27 do sexo feminino e 20 do masculino], 62% deles com infecção por Hp. Todos os 5 métodos concordaram em 61%, sendo negativo em 21% e positivo em 40%. As maiores concordâncias entre dois métodos ocorreram entre os métodos invasivos: histologia e teste rápido da urease (89,6%) e entre a histologia e cultura (87,5%). A maior sensibilidade, considerando como Hp positivo, qualquer combinação de 3 ou mais testes, foi encontrada no teste rápido da urease (S=100%), seguido pela histologia, sorologia e o teste respiratório com uréia marcada com Carbono13 (S=93,1%) e por fim a cultura (S=79,3%). A maior especificidade foi obtida pela histologia e cultura (100%), seguidos pelo teste rápido da urease (84,2%), sorologia (78,9%) e teste respiratório com uréia marcada com Carbono13 (78,9%). CONCLUSÕES: Nossos resultados sugerem que, entre os métodos invasivos, a associação do teste rápido da urease e histologia constituem a melhor escolha para a detecção da infecção por Hp. Se os resultados da histologia e do teste rápido da urease forem discordantes é recomendada a sorologia.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Pediatric DepartmentUNIFESP, EPM, Pediatric DepartmentSciEL