A prospective analysis of low-grade gastric malt lymphoma after Helicobacter pylori eradication

BACKGROUND: Primary gastric low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is known to be successfully treated with anti-Helicobacter pylori (H. pylori) therapy alone. However, there are few reports on long-term results after eradication therapy. The aims of this study were to analyze the rate and the interval to reach complete remission (CR), and to assess the rate and the factors affecting recurrence of MALT lymphoma. MATERIALS AND METHODS: Between 1996 and 2003, a total of 90 H. pylori-infected patients with low-grade MALT lymphoma were included in this study. For initial staging, endoscopic ultrasonography, chest-abdomen-pelvis CT scans, and bone marrow examination were taken. All patients were made to take anti-H. pylori therapy for 14 days. Tumoral response was assessed by endoscopy every 3 months till CR and every 6 months after achieving CR. RESULTS: Among 90 treated patients, 85 (94.4%) reached CR. The median interval to CR was 3 months (range, 1-24). Seventy-nine (92.9%) patients were in CR at 12 months. Median follow-up period after CR was 45 months (range 15-109). Among 77 patients who were followed-up after CR, 8 (10.4%) patients were proved with recurrence of MALT lymphoma. Cumulative recurrence rate was 2.7, 11.5, and 12.2% at 1, 2, and 3 years. The presence of H. pylori was only a significant risk factor affecting recurrence. CONCLUSIONS: The status of H. pylori is the most important risk factor affecting recurrence. Therefore, adequate eradication regimen and accurate regular evaluation for H. pylori status are needed during follow up of primary gastric low-grade B-cell MALT lymphoma.     

Functional responses of aphid parasitoids,Aphidius colemani (Hymenoptera: Braconidae) and Aphelinus asychis (Hymenoptera: Aphelinidae)

We evaluated the functional responses of two aphid parasitoids: Aphidius colemani on the green peach aphid Myzus persicae (Hemiptera: Aphididae), and Aphelinus asychis on M. persicae and the potato aphid, Macrosiphum euphorbiae (Hemiptera: Aphididae). Parasitoid oviposition occurred at host densities of 5, 10, 20, 30, 50, 80 or 100 aphids for A. colemani and 5, 10, 20, 30 or 50 aphids for A. asychis. More M. persicae were parasitized by A. colemani than by A. asychis at an aphid density of 50. Among the three types of functional response, type III best described the parasitoid response to the host densities both in A. colemani and A. asychis. The estimated handling time was shorter for A. colemani than for A. asychis (0.017 and 0.043 d, respectively). The proportion of aphids that were parasitized exhibited the same characteristic curve among the three host-parasitoid combinations: a wave form that appeared to be a composite of a decelerating (as in type II) response at low host density and an accelerating-and-decelerating (as in type III) response at medium to high host density. We hypothesize that the novel host species (and its host plant), density-dependent superparasitism, and/or density-dependent host-killing may have induced the modified type III response.     

Effect of climate change on the potential distribution of the common cutworm (Spodoptera litura) in South Korea

Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), known as common cutworm, is a worldwide pest that causes severe damage to various crops and vegetables in South Korea. In this study, we predicted the potential distribution of S. litura in South Korea in a climate change scenario by applying species distribution modeling. We used the CLIMEX software as a main tool and determined optimal parameter values to simulate the current distribution of S. litura in Asia. We then used these parameter values to predict the species' future distribution in South Korea. As a result, we prepared maps indicating areas with suitable climate for S. litura and showed that these areas gradually increased as a result of climate change. Approximately 98% of the areas in South Korea were predicted to have a favorable climate for S. litura in 2100; 63.2% of the area in South Korea is currently favorable. To the best of our knowledge, this is the first study to predict the potential distribution of S. litura in South Korea, and it provides the basic data necessary to establish an optimal control strategy of this species.     

Dissection of Binding between a Phosphorylated Tyrosine Hydroxylase Peptide and 14-3-3ζ: A Complex Story Elucidated by NMR

Human tyrosine hydroxylase activity is regulated by phosphorylation of its N-terminus and by an interaction with the modulator 14-3-3 proteins. We investigated the binding of singly or doubly phosphorylated and thiophosphorylated peptides, comprising the first 50 amino acids of human tyrosine hydroxylase, isoform 1 (hTH1), that contain the critical interaction domain, to 14-3-3ζ, by ³¹P NMR. Single phosphorylation at S19 generates a high affinity 14-3-3ζ binding epitope, whereas singly S40-phosphorylated peptide interacts with 14-3-3ζ one order-of-magnitude weaker than the S19-phosphorylated peptide. Analysis of the binding data revealed that the 14-3-3ζ dimer and the S19- and S40-doubly phosphorylated peptide interact in multiple ways, with three major complexes formed: 1), a single peptide bound to a 14-3-3ζ dimer via the S19 phosphate with the S40 phosphate occupying the other binding site; 2), a single peptide bound to a 14-3-3ζ dimer via the S19 phosphorous with the S40 free in solution; or 3), a 14-3-3ζ dimer with two peptides bound via the S19 phosphorous to each binding site. Our system and data provide information as to the possible mechanisms by which 14-3-3 can engage binding partners that possess two phosphorylation sites on flexible tails. Whether these will be realized in any particular interacting pair will naturally depend on the details of each system.     

Histomorphological and Immunophenotypic Features of Pill-Induced Esophagitis

The aim of this study was to investigate histomorphological and immunophenotypic features in pill-induced esophagitis. We comparatively evaluated the histomorphological, immunophenotypic features of pill-induced esophagitis vs. reflux esophagitis, as well as clinical information and endoscopic findings. Fifty-two tissue pieces from 22 cases of pill-induced esophagitis, 46 pieces from 20 reflux esophagitis, and 16 pieces from 14 control samples were subjected to immunohistochemistry for inflammatory infiltrates (CD3 for T lymphocyte, CD20 for B lymphocyte, CD56 for NK cell, CD68 for macrophage, CD117 for mast cell) and eosinophil chemotaxis-associated proteins (Erk, leptin, leptin receptor, pSTAT3, phospho-mTOR). As a result, Histomorphology showed that a diffuse pattern of dilated intercellular spaces was more frequently observed in pill-induced esophagitis, while reactive atypia and subepithelial papillary elongation were more often found in reflux esophagitis (P < 0.05, respectively). Interestingly, intraepithelial eosinophilic microabscess, intraepithelial pustule and diffuse pattern of dilated intercellular spaces were observed in 14% (3 cases), 9% (2 cases) and 32% (7 cases) of pill-induced esophagitis, respectively, but in no cases of reflux esophagitis. Regarding intraepithelial inflammatory infiltrates in pill-induced esophagitis, T lymphocytes were the most common cells, followed by eosinophil; 11 and 7 in one x400 power field, respectively. Intraepithelial pSTAT3-positive pattern was more frequently observed in pill-induced esophagitis than in reflux esophagitis, at 45% (10 cases) versus 10% (2 cases), respectively (P < 0.05). Considering the distal esophageal lesion only, intraepithelial pustule, diffuse dilated intercellular spaces and stromal macrophages were more frequently found in distal pill-induced esophagitis, whereas reactive atypia and intraepithelial mast cells in reflux esophagitis (P < 0.05, respectively). In conclusion, diffuse dilated intercellular spaces, intraepithelial eosinophil microabscess, pustule, T lymphocytes, eosinophils, and pSTAT3 positivity can be added to histopathological features of pill-induced esophagitis, other than non-specific ulcer. Besides, distal pill-induced esophagitis may be histopathologically differentiated from reflux esophagitis.     

Tumor suppressor INK4: determination of the solution structure of p18INK4C and demonstration of the functional significance of loops in p18INK4C and p16INK4A

Since the structures of several ankyrin-repeat proteins including the INK4 (inhibitor of cyclin-dependent kinase 4) family have been reported recently, the detailed structures and the functional roles of the loops have drawn considerable interest. This paper addresses the potential importance of the loops of ankyrin-repeat proteins in three aspects. First, the solution structure of p18INK4C was determined by NMR, and the loop structures were analyzed in detail. The loops adapt nascent antiparallel beta-sheet structures, but the positions are slightly different from those in the crystal structure. A detailed comparison between the solution structures of p16 and p18 has also been presented. The determination of the p18 solution structure made such detailed comparisons possible for the first time. Second, the [1H,15N]HSQC NMR experiment was used to probe the interactions between p18INK4C and other proteins. The results suggest that p18INK4C interacts very weakly with dna K and glutathione S-transferase via the loops. The third aspect employed site-specific mutagenesis and functional assays. Three mutants of p18 and 11 mutants of p16 were constructed to test functional importance of loops and helices. The results suggest that loop 2 is likely to be part of the recognition surface of p18INK4C or p16INK4A for CDK4, and they provide quantitative functional contributions of specific residues. Overall, our results enhance understanding of the structural and functional roles of the loops in INK4 tumor suppressors in particular and in ankyrin-repeat proteins in general.     

A protein contortionist: core mutations of GB1 that induce dimerization and domain swapping

Immunoglobulin-binding domain B1 of streptococcal protein G (GB1), a small (56 residues), stable, single-domain protein, is one of the most extensively used model systems in the area of protein folding and design. Recently, NMR and X-ray structures of a quintuple GB1 core mutant (L5V/A26F/F30V/Y33F/A34F) that showed an unexpected, intertwined tetrameric architecture were determined. Here, we report the NMR structure of another mutant, derived from the tetramer by reverting the single amino acid position F26 back to the wild-type sequence A26. The structure reveals a domain-swapped dimer that involves exchange of the second beta-hairpin. The resulting overall structure comprises an eight-stranded beta-sheet whose concave side is covered by two alpha helices. The dimer dissociates into a partially folded, monomeric species with a dissociation constant of 93(+/-10)microM.