101 research outputs found
Host strain specific sex pheromone variation in Spodoptera frugiperda
<p>Abstract</p> <p>Background</p> <p>The fall armyworm <it>Spodoptera frugiperda </it>(Lepidoptera; Noctuidae) consists of two distinct strains with different host plant preferences for corn and rice. To assess whether pheromonal-mediated behavioral isolation accompanies the habitat isolation on different host plants, we compared the sex pheromone composition among females of the two strains. Pheromone glands were extracted with or without injection of pheromone biosynthesis activating neuropeptide (PBAN). To assess the mode of inheritance of this variation, we also analyzed the pheromone composition of F<sub>1 </sub>hybrid females.</p> <p>Results</p> <p>Relative to intra-strain variation, the pheromone composition of the two strains differed significantly. Corn strain females contained significantly more of the second most abundant pheromone compound Z11-16:Ac (m), and significantly less of most other compounds, than rice strain females. When females were injected with PBAN before their glands were extracted, the differences between the strains were less pronounced but still statistically significant. The pheromone composition of hybrid females showed a maternal inheritance of the major component Z9-14:Ac (M) as well as of Z11-16:Ac (m). Most other compounds showed an inheritance indicating genetic dominance of the corn strain. The within-strain phenotypic correlations among the various components were consistent with their hypothesized biosynthetic pathway, and between-strain differences in the correlation structure suggested candidate genes that may explain the pheromone differences between the two strains. These include Δ9- and Δ11 desaturases, and possibly also a Δ7-desaturase, although the latter has not been identified in insects so far.</p> <p>Conclusion</p> <p>The two host strains of <it>S. frugiperda </it>produce systematically differing female sex pheromone blends. Previously-documented geographic variation in the sexual communication of this species did not take strain identity into account, and thus may be partly explained by different strain occurrence in different regions. The finding of pheromone differences reinforces the possibility of incipient reproductive isolation among these strains, previously shown to differ in the timing of nocturnal mating activity and host plant use. Finding the genetic basis of the pheromone differences, as well as these other biological traits, will help to elucidate the role of premating isolation in the continuing differentiation of these two strains that may eventually lead to speciation.</p
Within-population variability in a moth sex pheromone blend, part 2: selection towards fixation
HCC risk stratification after cure of hepatitis C in patients with compensated advanced chronic liver disease
Background&Aims:
Hepatocellular carcinoma (HCC) is a main cause of morbidity and mortality in patients with advanced chronic liver disease (ACLD) due to chronic hepatitis C and who have achieved sustained virologic response (SVR).
We elaborated risk stratification algorithms for de-novo-HCC-development after SVR and validated them in an independent cohort.
Methods:
Derivation cohort: 527 patients with pre-treatment ACLD and SVR to interferon-free therapy were evaluated for de-novo-HCC-development. Among others, alpha-fetoprotein (AFP) and non-invasive surrogates of portal hypertension including liver stiffness measurement (LSM) were assessed pre-/post-treatment. Validation cohort: 1500 patients with compensated ACLD (cACLD) from other European centers.
Results:
During a median follow-up (FU) of 41 months, 22/475 cACLD (4.6%) (1.45/100patient-years)vs.12/52 decompensated patients (23.1%, 7.00/100patient-years, p<0.001) developed de-novo-HCC. Since decompensated patients were at substantial HCC-risk, we focused on cACLD for all further analyses.
In cACLD, post-treatment-values showed a higher discriminative ability for patients with/without de-novo-HCC-development during FU than pre-treatment-values or absolute/relative changes. Models based on post-treatment AFP≥4.6ngxmL-1-3points, alcohol consumption (males:>30g/d/females:>20g/d)-2points (optional), age≥59year-2points, LSM≥19.0kPa-1point, and albumin<42gxL-1-1point, accurately predicted de-novo-HCC-development (bootstrapped Harrel’s C with and without considering alcohol:0.893 and 0.836). Importantly, these parameters also provided independent prognostic information in competing risk analysis and accurately stratified patients into low-(0-3points; ≈2/3 of patients) and high-risk (≥4points; ≈1/3) groups in the derivation (algorithm with alcohol consumption; 4-year HCC-risk:0%vs.16.5%) and validation (3.3%/17.5%) cohorts. An alternative approach based on age/alcohol (optional)/FU-LSM/FU-albumin (i.e., without FU-AFP) also showed a robust performance.
Conclusions:
Simple algorithms based on post-treatment age/albumin/LSM, and optionally, AFP and alcohol, accurately stratified de-novo-HCC-risk in cACLD patients with SVR. Approximately 2/3 were identified as having an HCC-risk <1%/y in both the derivation and validation cohort, thereby clearly falling below the cost-effectiveness threshold for HCC-surveillance.
LAY SUMMARY:
Simple algorithms based on age, alcohol consumption, results of blood tests (albumin and α-fetoprotein), as well as liver stiffness measurement after the end of hepatitis C treatment identify a large proportion (approximately 2/3) of patients with advanced but still asymptomatic liver disease who are at very low risk (<1%/year) of liver cancer development, and thus, might not need to undergo 6-monthly liver ultrasound
Extracellular nucleotides inhibit growth of human oesophageal cancer cells via P2Y2-receptors
Extracellular ATP is known to inhibit growth of various tumours by activating specific purinergic receptors (P2-receptors). Since the therapy of advanced oesophageal cancer is unsatisfying, new therapeutic approaches are mandatory. Here, we investigated the functional expression and potential antiproliferative effects of P2-purinergic receptors in human oesophageal cancer cells. Prolonged incubation of primary cell cultures of human oesophageal cancers as well as of the squamous oesophageal cancer cell line Kyse-140 with ATP or its stable analogue ATPγS dose-dependently inhibited cell proliferation. This was due to both an induction of apoptosis and cell cycle arrest. The expression of P2-receptors was examined by RT-PCR, immunocytochemistry, and [Ca2+]i-imaging. Application of various extracellular nucleotides dose-dependently increased [Ca2+]i. The rank order of potency was ATP=UTP>ATPγS>ADP=UDP. 2-methylthio-ATP and α,β-methylene-ATP had no effects on [Ca2+]i. Complete cross-desensitization between ATP and UTP was observed. Moreover, the phospholipase C inhibitor U73122 dose-dependently reduced the ATP triggered [Ca2+]i signal. The pharmacological features strongly suggest the functional expression of G-protein coupled P2Y2-receptors in oesophageal squamous cancer cells. P2Y2-receptors are involved in the antiproliferative actions of extracellular nucleotides. Thus, P2Y2-receptors are promising target proteins for innovative approaches in oesophageal cancer therapy
Histologic assessment of biliary obstruction with different percutaneous endoluminal techniques
BACKGROUND: Despite the sophisticated cross sectional image techniques currently available, a number of biliary stenosis or obstructions remain of an uncertain nature. In these pathological conditions, an "intrinsic" parietal alteration is the cause of biliary obstruction and it is very difficult to differentiate benign from malignant lesions using cross-sectional imaging procedures alone. We evaluated the efficacy of different endoluminal techniques to achieve a definitive pathological diagnosis in these situations. METHODS: Eighty patients underwent brushing, and or biopsy of the biliary tree through an existing transhepatic biliary drainage route. A subcoort of 12 patients needed balloon-dilatation of the bile duct and the material covering the balloon surface was also sent for pathological examination (balloon surface sampling). Pathological results were compared with surgical findings or with long-term clinical and instrumental follow-ups. Success rates, sensitivity, specificity, accuracy, confidential intervals, positive predictive value and negative predictive value of the three percutaneous techniques in differentiating benign from malignant disease were assessed. The agreement coefficient of biopsy and brushing with final diagnosis was calculated using the Cohen's "K" value. RESULTS: Fifty-six patients had malignant strictures confirmed by surgery, histology, and by clinical follow-ups. Success rates of brushing, balloon surface sampling, and biopsy were 90.7, 100, and 100%, respectively. The comparative efficacy of brushing, balloon-surface sampling, and biopsy resulted as follows: sensitivity of 47.8, 87.5, and 92.1%, respectively; specificity of 100% for all the techniques; accuracy of 69.2, 91.7 and 93.6%, Positive Predictive Value of 100% for all the procedures and Negative Predictive Value of 55, 80, and 75%, respectively. CONCLUSIONS: Percutaneous endoluminal biopsy is more accurate and sensitive than percutaneous bile duct brushing in the detection of malignant diseases (p < 0.01)
ABO allele-level frequency estimation based on population-scale genotyping by next generation sequencing
The Chlamydia psittaci Genome: A Comparative Analysis of Intracellular Pathogens
Chlamydiaceae are a family of obligate intracellular pathogens causing a wide range of diseases in animals and humans, and facing unique evolutionary constraints not encountered by free-living prokaryotes. To investigate genomic aspects of infection, virulence and host preference we have sequenced Chlamydia psittaci, the pathogenic agent of ornithosis.A comparison of the genome of the avian Chlamydia psittaci isolate 6BC with the genomes of other chlamydial species, C. trachomatis, C. muridarum, C. pneumoniae, C. abortus, C. felis and C. caviae, revealed a high level of sequence conservation and synteny across taxa, with the major exception of the human pathogen C. trachomatis. Important differences manifest in the polymorphic membrane protein family specific for the Chlamydiae and in the highly variable chlamydial plasticity zone. We identified a number of psittaci-specific polymorphic membrane proteins of the G family that may be related to differences in host-range and/or virulence as compared to closely related Chlamydiaceae. We calculated non-synonymous to synonymous substitution rate ratios for pairs of orthologous genes to identify putative targets of adaptive evolution and predicted type III secreted effector proteins.This study is the first detailed analysis of the Chlamydia psittaci genome sequence. It provides insights in the genome architecture of C. psittaci and proposes a number of novel candidate genes mostly of yet unknown function that may be important for pathogen-host interactions
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