Antigen recognition is facilitated by invadosome-like protrusions formed by memory/effector T cells

Adaptive immunity requires that T cells efficiently scan diverse cell surfaces to identify cognate Ag. However, the basic cellular mechanisms remain unclear. In this study, we investigated this process using vascular endothelial cells, APCs that possess a unique and extremely advantageous, planar morphology. High-resolution imaging revealed that CD4 memory/effector T cells dynamically probe the endothelium by extending submicron-scale, actin-rich "invadosome/podosome-like protrusions" (ILPs). The intimate intercellular contacts enforced by ILPs consistently preceded and supported T cell activation in response to endothelial MHC class II/Ag. The resulting calcium flux stabilized dense arrays of ILPs (each enriched in TCR, protein kinase C-θ, ZAP70, phosphotyrosine, and HS1), forming what we term a podo-synapse. Similar findings were made using CD8 CTLs on endothelium. Furthermore, careful re-examination of both traditional APC models and professional APCs suggests broad relevance for ILPs in facilitating Ag recognition. Together, our results indicate that ILPs function as sensory organelles that serve as actuators of immune surveillance.     

Cryo-tolerance of zygotic embryos from recalcitrant seeds in relation to oxidative stress--a case study on two amaryllid species

Oxidative stress is a major component of cryoinjury in plant tissues. This study investigated the ability of recalcitrant (i.e. desiccation sensitive) Amaryllis belladonna L. and Haemanthus montanus Baker zygotic embryos to survive cryopreservation, in relation to oxidative stress. The study also investigated whether glycerol cryoprotection promoted embryo post-cryo survival by protecting enzymic antioxidant activities. Zygotic embryos excised from hydrated stored seeds were subjected to various combinations of rapid dehydration (to < or >0.4 g g?1 [dmb]), cryoprotection (with sucrose or glycerol), and cooling (either rapidly or slowly), and were thereafter assessed for viability, extracellular superoxide (·O??) production, lipid peroxidation (TBARS) and antioxidant enzyme activities. Short-term hydrated storage of whole seeds was accompanied by ·O?? production and lipid peroxidation, but ·O?? levels were lower than in dehydrated and cooled embryos and viability was 100%, possibly associated with the high activities of certain antioxidant enzymes. Partial dehydration and cryoprotection (in H. montanus only) increased ·O?? production (especially in cryoprotected-dried embryos) and was associated with some viability loss, but this was not correlated with enhanced lipid peroxidation. Cooling was generally accompanied by the greatest increase in ·O?? production, and with a decline in viability. In A. belladonna only, post-cryo TBARS levels were generally higher than for fresh and pre-conditioned embryos. Partial dehydration and cooling decreased antioxidant activities, but these were consistently less severe in glycerol cryoprotected-dried, as opposed to non-cryoprotected-dried embryos. Post-cryo viability retention for glycerol cryoprotected-dried embryos was significantly higher than for non-cryoprotected-dried embryos, possibly facilitated by relatively low post-drying TBARS levels and high post-drying and post-rewarming activities of some antioxidant enzymes in the former. Pre-conditioning treatments such as glycerol cryoprotection, when used in combination with partial drying, may enhance post-cryo viability retention in recalcitrant zygotic embryos by protecting the activities of certain antioxidant enzymes during pre-conditioning for, and after retrieval from, cryostorage.     

Crystallographic studies on N-azidoacetyl-beta-D-glucopyranosylamine, an inhibitor of glycogen phosphorylase: comparison with N-acetyl-beta-D-glucopyranosylamine

N-acetyl-beta-D-glucopyranosylamine (NAG) is a potent inhibitor (Ki=32 microM) of glycogen phosphorylase b (GPb), and has been employed as a lead compound for the structure-based design of new analogues, in an effort to utilize its potential as a hypoglycaemic agent. Replacement of the acetamido group by azidoacetamido group resulted in an inhibitor, N-azidoacetyl-beta-D-glucopyranosylamine (azido-NAG), with a Ki value of 48.7 microM, in the direction of glycogen synthesis. In order to elucidate the mechanism of inhibition, we determined the ligand structure in complex with GPb at 2.03 A resolution, and the structure of the fully acetylated derivative in the free form. The molecular packing of the latter is stabilized by a number of bifurcated hydrogen bonds of which the one involving a bifurcated C-H...N...H-C type hydrogen bonding is rather unique in organic azides. Azido-NAG can be accommodated in the catalytic site of T-state GPb at approximately the same position as that of NAG and stabilizes the T-state conformation of the 280 s loop by making several favourable contacts to residues of this loop. The difference observed in the Ki values of the two analogues can be interpreted in terms of desolvation effects, subtle structural changes of protein residues and changes in water structure.     

Improving the permeability of the hydroxyethylamine BACE-1 inhibitors: Structure–activity relationship of P2′ substituents

Herein we describe further evolution of hydroxyethylamine inhibitors of BACE-1 with enhanced permeability characteristics necessary for CNS penetration. Variation at the P2′ position of the inhibitor with more polar substituents led to compounds 19 and 32, which retained the potency of more lipophilic analog 1 but with much higher observed passive permeability in MDCK cellular assay.     

Unusual intron in the second exon of a Type III polyketide synthase gene of Alpinia calcarata Rosc

Plant phenolic compounds form a valuable resource of secondary metabolites having a broad spectrum of biological activities. Type III polyketide synthases play a key role in the formation of basic structural skeleton of the phenolic compounds. As a group of medicinal plants, PKSs with novel features are expected in the genome of Zingiberaceae. The genomic exploration of PKS in Alpinia calcarata conducted in this study identified the presence of an unusual intron at the region forming the second exon of typical PKSs, forming a gateway information of distribution of novel PKSs in Zingiberaceae.     

Root-knot nematodes exhibit strain-specific clumping behavior that is inherited as a simple genetic trait

Root-knot nematodes are obligate parasites of a wide range of plant species and can feed only on the cytoplasm of living plant cells. In the absence of a suitable plant host, infective juveniles of strain VW9 of the Northern root-knot nematode, Meloidogyne hapla, when dispersed in Pluronic F-127 gel, aggregate into tight, spherical clumps containing thousands of worms. Aggregation or clumping behavior has been observed in diverse genera in the phylum Nematoda spanning free-living species such as Caenorhabditis elegans as well as both plant and animal parasites. Clumping behavior differs between strains of M. hapla and occurs with other species within this genus where strain-specific differences in clumping ability are also apparent. Exposure of M. hapla juveniles to a gradient formed using low levels of cyanide promotes formation of clumps at a preferred cyanide level. Analysis of F2 lines from a cross of M. hapla strains that differ in clump-forming behavior reveals that the behavior segregates as a single, major locus that can be positioned on the genetic map of this nematode. Clumping behavior may be a survival strategy whose importance and function depend on the niche of the nematode strain or species.     

Folate-targeted immunotherapy effectively treats established adjuvant and collagen-induced arthritis

Activated macrophages express a cell surface receptor for the vitamin folic acid. Because this receptor is inaccessible or not measurably expressed on other normal cells, folic acid has been recently exploited to selectively deliver attached radio-emitters to sites of activated macrophage accumulation, allowing scintigraphic imaging of inflamed joints and organs of arthritic rats. We demonstrate here that folate-linked haptens can also be targeted to activated macrophages, decorating their cell surfaces with highly immunogenic molecules. Under conditions in which the rodent has already been immunized against keyhole limpet hemocyanine-(fluorescein isothiocyanate) FITC, activated macrophages are eliminated. Administration of folate-FITC conjugates to rodents with experimental arthritis attenuates (a) systemic and peri-articular inflammation, (b) bone and cartilage degradation, and (c) arthritis-related body weight loss. Treatment with folate-hapten conjugates is comparable to methotrexate, etanercept, anakinra, and celecoxib at alleviating the symptoms of arthritis. We conclude that reduction of activated macrophages by folate-targeted immunotherapy can ameliorate the symptoms of arthritis in two rodent models of the disease.     

Age-associated adipose tissue inflammation promotes monocyte chemotaxis and enhances atherosclerosis

Although aging enhances atherosclerosis, we do not know if this occurs via alterations in circulating immune cells, lipid metabolism, vasculature, or adipose tissue. Here, we examined whether aging exerts a direct pro-atherogenic effect on adipose tissue in mice. After demonstrating that aging augmented the inflammatory profile of visceral but not subcutaneous adipose tissue, we transplanted visceral fat from young or aged mice onto the right carotid artery of Ldlr^−/− recipients. Aged fat transplants not only increased atherosclerotic plaque size with increased macrophage numbers in the adjacent carotid artery, but also in distal vascular territories, indicating that aging of the adipose tissue enhances atherosclerosis via secreted factors. By depleting macrophages from the visceral fat, we identified that adipose tissue macrophages are major contributors of the secreted factors. To identify these inflammatory factors, we found that aged fat transplants secreted increased levels of the inflammatory mediators TNFα, CXCL2, and CCL2, which synergized to promote monocyte chemotaxis. Importantly, the combined blockade of these inflammatory mediators impeded the ability of aged fat transplants to enhance atherosclerosis. In conclusion, our study reveals that aging enhances atherosclerosis via increased inflammation of visceral fat. Our study suggests that future therapies targeting the visceral fat may reduce atherosclerosis disease burden in the expanding older population.     

Influence of angles occlusion in periodontal diseases

It is of interest to document the known relationship between periodontal status and Angle''s malocclusion types. We used 26092 case records of patients between 16 to 50 years of age with no gender restrictions. Variables such as age, gender, periodontal diagnosis and type of Angle''s occlusion were extracted and tabulated. Statistical analysis was completed using chi square test in the SPSS software version 20. Data shows that the majority (95.27%) had Angle''s class I occlusion and less than 5% had class II and Class III occlusion. Statistical analysis of class II and Class III cases with 1000 randomly selected cases of class I occlusion show a significant difference in the periodontal status between different types of Angle''s occlusion. Chronic periodontitis was more in class I (10.4%) and it was the lowest in Class II Div 2 (4.3%) occlusion. Class II Div 1(23.8%) and Class III (17%) had the highest and lowest proportion of clinically healthy periodontium, respectively. Thus, we report that angles occlusion types had significant influence on periodontal status along with the other determinants.