Effects of Pratylenchus coffeae—Tylenchulus semipenetrans Interactions on Nematode Population Dynamics in Citrus

The distributions of Pratylenchus coffeae and Tylenchulus semipenetrans in a central Florida citrus grove were mutually exclusive. In a challenge experiment conducted in the grove, indigenous populations of either species did not prevlude infection by the other species. Inoculation with either T. semipenetrans or P. coffeae tended to reduce the population size of the other nematode species. In greenhouse tests, individual feeder roots were parasitized predominantly by one or the other of the two species. Host response to parasitism in dual infections did not differ from response to single infection by either species.     

B lymphocyte autoimmunity in rheumatoid synovitis is independent of ectopic lymphoid neogenesis

B lymphocyte autoimmunity plays a crucial role in the pathogenesis of rheumatoid arthritis. The local production of autoantibodies and the presence of ectopic lymphoid neogenesis in the rheumatoid synovium suggest that these dedicated microenvironments resembling canonical lymphoid follicles may regulate the initiation and maturation of B cell autoimmunity. In this study, we assessed experimentally the relevance of ectopic lymphoid neogenesis for B cell autoimmunity by a detailed structural, molecular, and serological analysis of seropositive and seronegative human synovitis. We demonstrate that synovial lymphoid neogenesis is a reversible process associated with inflammation which is neither restricted to nor preferentially associated with autoantibody positive rheumatic conditions. Despite the abundant expression of key chemokines and cytokines required for full differentiation toward germinal center reactions, synovial lymphoid neogenesis in rheumatoid arthritis only occasionally progresses toward fully differentiated follicles. In agreement with that observation, we could not detect Ag-driven clonal expansion and affinity maturation of B lymphocytes. Furthermore, ectopic lymphoid neogenesis is not directly associated with local production of anti-citrullinated protein Abs and rheumatoid factor in the rheumatoid joint. Therefore, we conclude that synovial lymphoid neogenesis is not a major determinant of these rheumatoid arthritis-specific autoantibody responses.     

Non-bacterial thrombotic endocarditis in metastatic caecal adenocarcinoma

A 34-year-old woman was admitted because of headache, blurred vision, apraxia and abnormal feeling in the right arm. Examination revealed finger petechiae. Infection parameters were low. Magnetic resonance imaging of the brain showed multiple cortical and white matter lesions.     

A Dutch guideline for the treatment of scoliosis in neuromuscular disorders

Background

Children with neuromuscular disorders with a progressive muscle weakness such as Duchenne Muscular Dystrophy and Spinal Muscular Atrophy frequently develop a progressive scoliosis. A severe scoliosis compromises respiratory function and makes sitting more difficult. Spinal surgery is considered the primary treatment option for correcting severe scoliosis in neuromuscular disorders. Surgery in this population requires a multidisciplinary approach, careful planning, dedicated surgical procedures, and specialized after care.

Methods

The guideline is based on scientific evidence and expert opinions. A multidisciplinary working group representing experts from all relevant specialties performed the research. A literature search was conducted to collect scientific evidence in answer to specific questions posed by the working group. Literature was classified according to the level of evidence.

Results

For most aspects of the treatment scientific evidence is scarce and only low level cohort studies were found. Nevertheless, a high degree of consensus was reached about the management of patients with scoliosis in neuromuscular disorders. This was translated into a set of recommendations, which are now officially accepted as a general guideline in the Netherlands.

Conclusion

In order to optimize the treatment for scoliosis in neuromuscular disorders a Dutch guideline has been composed. This evidence-based, multidisciplinary guideline addresses conservative treatment, the preoperative, perioperative, and postoperative care of scoliosis in neuromuscular disorders.     

Localization of the urea transporter UT-B protein in human and rat erythrocytes and tissues

A new polyclonal antibody to the humanerythrocyte urea transporter UT-B detects a broad band between 45 and65 kDa in human erythrocytes and between 37 and 51 kDa in raterythrocytes. In human erythrocytes, the UT-B protein is the Kidd (Jk)antigen, and Jk(a+b+) erythrocytes express the 45- to 65-kDa band.However, in Jk null erythrocytes [Jk(ab)], only a faint band at55 kDa is detected. In kidney medulla, a broad band between 41 and 54 kDa, as well as a larger band at 98 kDa, is detected. Human and ratkidney show UT-B staining in nonfenestrated endothelial cells indescending vasa recta. UT-B protein and mRNA are detected in rat brain,colon, heart, liver, lung, and testis. When kidney medulla or liverproteins are analyzed with the use of a native gel, only a singleprotein band is detected. UT-B protein is detected in cultured bovineendothelial cells. We conclude that UT-B protein is expressed in morerat tissues than previously reported, as well as in erythrocytes.

     

Model selection in non-nested hidden Markov models for ion channel gating

An important task in the application of Markov models to the analysis of ion channel data is the determination of the correct gating scheme of the ion channel under investigation. Some prior knowledge from other experiments can reduce significantly the number of possible models. If these models are standard statistical procedures nested like likelihood ratio testing, provide reliable selection methods. In the case of non-nested models, information criteria like AIC, BIC, etc., are used. However, it is not known if any of these criteria provide a reliable selection method and which is the best one in the context of ion channel gating. We provide an alternative approach to model selection in the case of non-nested models with an equal number of open and closed states. The models to choose from are embedded in a properly defined general model. Therefore, we circumvent the problems of model selection in the non-nested case and can apply model selection procedures for nested models.     

Normalization of DNA-microarray data by nonlinear correlation maximization.

Signal data from DNA-microarray ("chip") technology can be noisy; i.e., the signal variation of one gene on a series of repetitive chips can be substantial. It is becoming more and more recognized that a sufficient number of chip replicates has to be made in order to separate correct from incorrect signals. To reduce the systematic fraction of the noise deriving from pipetting errors, from different treatment of chips during hybridization, and from chip-to-chip manufacturing variability, normalization schemes are employed. We present here an iterative nonparametric nonlinear normalization scheme called simultaneous alternating conditional expectation (sACE), which is designed to maximize correlation between chip repeats in all-chip-against-all space. We tested sACE on 28 experiments with 158 Affymetrix one-color chips. The procedure should be equally applicable to other DNA-microarray technologies, e.g., two-color chips. We show that the reduction of noise compared to a simple normalization scheme like the widely used linear global normalization leads to fewer false-positive calls, i.e., to fewer genes which have to be laboriously confirmed by independent methods such as TaqMan or quantitative PCR.     

Recruitment of the proneural gene scute to the Drosophila sex-determination pathway

In flies, scute (sc) works with its paralogs in the achaete-scute-complex (ASC) to direct neuronal development. However, in the family Drosophilidae, sc also acquired a role in the primary event of sex determination, X chromosome counting, by becoming an X chromosome signal element (XSE)-an evolutionary step shown here to have occurred after sc diverged from its closest paralog, achaete (ac). Two temperature-sensitive alleles, sc(sisB2) and sc(sisB3), which disrupt only sex determination, were recovered in a powerful F1 genetic selection and used to investigate how sc was recruited to the sex-determination pathway. sc(sisB2) revealed 3' nontranscribed regulatory sequences likely to be involved. The sc(sisB2) lesion abolished XSE activity when combined with mutations engineered in a sequence upstream of all XSEs. In contrast, changes in Sc protein sequence seem not to have been important for recruitment. The observation that the other new allele, sc(sisB3), eliminates the C-terminal half of Sc without affecting neurogenesis and that sc(sisB1), the most XSE-specific allele previously available, is a nonsense mutant, would seem to suggest the opposite, but we show that housefly Sc can substitute for fruit fly Sc in sex determination, despite lacking Drosophilidae-specific conserved residues in its C-terminal half. Lack of synergistic lethality among mutations in sc, twist, and dorsal argue against a proposed role for sc in mesoderm formation that had seemed potentially relevant to sex-pathway recruitment. The screen that yielded new sc alleles also generated autosomal duplications that argue against the textbook view that fruit fly sex signal evolution recruited a set of autosomal signal elements comparable to the XSEs.     

Evaluation of the in vitro degradation of macroporous hydrogels using gravimetry,confined compression testing,and microcomputed tomography

This study investigated the in vitro degradation characteristics of macroporous hydrogels based on poly(propylene fumarate-co-ethylene glycol) (P(PF-co-EG)). Four formulations were fabricated to test the effect of porosity and cross-linking density on the degradation of the resulting macroporous hydrogels. Macroporosity was introduced by the addition of sodium bicarbonate and ascorbic acid, the precursors of the carbon dioxide porogen, in the initiation system for the hydrogel cross-linking. Macroporous hydrogels with porosities of 0.80 +/- 0.03 and 0.89 +/- 0.03 were synthesized by the addition of sodium bicarbonate of concentrations 40 and 80 mg/mL and ascorbic acid of concentrations 0.05 and 0.1 mol/L, respectively. Poly(ethylene glycol) diacrylate (PEG-DA) was utilized as a cross-linker. The molecular weight between cross-links had a significant effect on weight loss after 12 weeks, where samples with M(C) of 1,880 +/- 320 synthesized with a P(PF-co-EG):PEG-DA ratio of 3:1 had a significantly greater mass loss due to degradation than those with M(C) of 1,000 +/- 100 synthesized with a P(PF-co-EG):PEG-DA ratio of 1:1. In contrast, porosity played a minimal role in determining the weight loss. Mechanical testing of the hydrogels under confined compression showed a decrease in compressive modulus over the degradation time for all formulations. In addition, an increase in hydrogel equilibrium water content and pore wall thickness was observed with degradation time, whereas the hydrogel porosity and surface area density remained invariant. The results from microcomputed tomography corroborated with the rest of the measurements and indicated a bulk degradation mechanism of the macroporous hydrogels.