A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

Production of DON-related trichothecenes byFusarium graminearum Schw from Krasnodarski krai of the USSR

34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals.     

Somatoform disorders among patients attending walk-in clinics in Trinidad: prevalence and association with depression and anxiety

Objectives Somatoform disorders are common in international primary care settings, but have been little studied in the developing world. The objective of this study was to determine the prevalence of severe undifferentiated somatoform disorder, and its relationship to depression and anxiety, among patients attending walk-in clinics in Trinidad.Methods The study participants, who were all aged 18 years or older and attending walk-in clinics at 16 randomly selected health centres, were surveyed between May and August 2007 using the PRIME-MD questionnaire.Results There were 594 participants (the response rate was 92%), of whom 72.7% were female. Their ages ranged from 18 to 93 years, and 54.5% were over 50 years of age. In total, 37.2% were married and 25.9% were single. Indo-Trinidadians represented 43.1% and Afro-Trinidadians represented 36% of the study sample; 56.5% of the participants reported that their income was less than US$ 400 per month, and 65.7% were unemployed. At walk-in clinics in Trinidad, the estimated prevalence of severe undifferentiated somatoform disorder was 10.3% (95% CI: 7.86–12.74), that of hypochondriasis was 28.5% (95% CI: 24.9–32.1), and that of body dysmorphic disorder was 15.8% (95% CI: 11.9–18.7). Severe undifferentiated somatoform disorder was statistically significantly associated with gender and ethnicity but not with age, level of education, employment status or income. Chi-square testing found significant associations between the presence of severe undifferentiated somatoform disorder and both depression and anxiety (P < 0.05), between hypochondriasis and both anxiety and depression (P < 0.05), and between body dysmorphic disorder and depression (P < 0.05) but not anxiety. Regression analysis suggested that the demographic features that predicted severe undifferentiated somatoform disorder were being female or Indo-Trinidadian.Conclusions Walk-in clinics in Trinidad that serve older patients on a lower income have a high proportion of patients with somatoform disorders as measured by the PRIME-MD scale. These patients exhibit many features of anxiety and depression. These findings have implications for medical training and service delivery.     

Marked differences between metalloproteases meprin A and B in substrate and peptide bond specificity

Meprin A and B are highly regulated, secreted, and cell-surface metalloendopeptidases that are abundantly expressed in the kidney and intestine. Meprin oligomers consist of evolutionarily related alpha and/or beta subunits. The work herein was carried out to identify bioactive peptides and proteins that are susceptible to hydrolysis by mouse meprins and kinetically characterize the hydrolysis. Gastrin-releasing peptide fragment 14-27 and gastrin 17, regulatory molecules of the gastrointestinal tract, were found to be the best peptide substrates for meprin A and B, respectively. Peptide libraries and a variety of naturally occurring peptides revealed that the meprin beta subunit has a clear preference for acidic amino acids in the P1 and P1' sites of substrates. The meprin alpha subunit selected for small (e.g. serine, alanine) or hydrophobic (e.g. phenylalanine) residues in the P1 and P1' sites, and proline was the most preferred amino acid at the P2' position. Thus, although the meprin alpha and beta subunits share 55% amino acid identity within the protease domain and are normally localized at the same tissue cell surfaces, they have very different substrate and peptide bond specificities indicating different functions. Homology models of the mouse meprin alpha and beta protease domains, based on the astacin crystal structure, revealed active site differences that can account for the marked differences in substrate specificity of the two subunits.     

Tetrahydroisoquinoline derivatives as melatonin MT2 receptor antagonists

A series of tetrahydroisoquinolines has yielded potent MT(2) receptor antagonists, which are selective versus the MT(1) receptor.     

Structure of homo- and hetero-oligomeric meprin metalloproteases. Dimers,tetramers, and high molecular mass multimers

Meprin A and B, metalloproteases consisting of evolutionarily related alpha and/or beta subunits, are membrane-bound and secreted enzymes expressed by kidney and intestinal epithelial cells, leukocytes, and cancer cells. Previous work established that the multidomain meprin subunits (each approximately 80 kDa) form disulfide-bridged homo- and heterodimers, and differ in substrate and peptide bond specificities. The work herein clearly demonstrates that meprin dimers differ markedly in their ability to oligomerize. Electrophoresis, light scattering, size exclusion chromatography, and electron microscopy were used to characterize quaternary structures of recombinant rat meprins. Meprin B, consisting of meprin beta subunits only, was dimeric under a wide range of conditions. By contrast, meprin alpha homodimers formed heterogeneous multimers (ring-, circle-, spiral-, and tube-like structures) containing up to 100 subunits, with molecular masses at protein peaks ranging from approximately 1.0 to 6.0 MDa. The size of the meprin alpha homo-oligomers was dependent on protein concentration, ionic strength, and activation state. Meprin alphabeta heterodimers tended to form tetramers but not higher oligomers. Thus, the presence of meprin beta, which has a transmembrane domain in vivo, restricts the oligomerization potential of meprin molecules and localizes meprins to the plasma membrane. By contrast, the propensity of secreted meprin alpha homodimers to self-associate concentrates proteolytic potential into high molecular mass multimers and thus allows for autocompartmentalization. The work indicates that different mechanisms exist to localize and concentrate the proteolytic activity of membrane-bound and secreted meprin metalloproteinases.     

Probing the active sites and mechanisms of rat metalloproteases meprin A and B

Meprin A and B are highly regulated, secreted and cell-surface homo- and hetero-oligomeric enzymes. Meprins are abundantly expressed in kidney and intestine. The multidomain alpha and beta subunits have high sequence identity, however they have very different substrate specificities, oligomerization potentials and are differentially regulated. Here we describe that meprin subunit activities are modulated differently by physico-chemical factors. Homo-oligomeric meprin B had an acidic pH optimum. The low pH protonation indicated the existence of at least two ionizable groups. An additional ionizable group generated a shoulder in the basic pH range. Homo-oligomeric meprin A had a neutral pH optimum and the activity curve revealed that two ionizable groups might be protonated at acidic pH similar to meprin B. Increasing the concentration of salt generally inhibited meprin B activity. Meprin A was inhibited at low salt concentrations but activated as salt was increased. This work has important implications in the elucidation of the catalytic mechanisms of meprins and other metalloproteases. In addition, the activity of meprin oligomers that arise in tissues will be affected by variations in pH and NaCl. This could have profound implications because meprins are exposed to a range of conditions in the extracellular milieu of renal and intestinal tissues and in inflammation and cancer.     

Meprin proteolytic complexes at the cell surface and in extracellular spaces

Meprins are metalloproteinases of the astacin family and metzincin superfamily that are composed of evolutionarily related alpha and beta subunits, which exist as homo- and hetero-oligomeric complexes. These complexes are abundant at the brush border membranes of kidney proximal tubule cells and epithelial cells of the intestine, and are also expressed in certain leucocytes and cancer cells. Meprins cleave bioactive peptides such as gastrin, cholecystokinin and parathyroid hormone, cytokines such as osteopontin and monocyte chemotactic peptide-1, as well as proteins such as gelatin, collagen IV, fibronectin and casein. Database predictions and initial data indicate that meprins are also capable of shedding proteins, including itself, from the cell surface. Membrane-bound meprin subunits are composed of dimeric meprin beta subunits or tetrameric hetero-oligomeric alpha beta complexes of approx. 200-400 kDa, and can be activated at the cell surface; secreted forms of homo-oligomeric meprin alpha are zymogens that form high-molecular-mass complexes of 1-6 MDa. These are among the largest extracellular proteases identified thus far. The latent (self-associating) homo-oligomeric complexes can move through extracellular spaces in a non-destructive manner, and deliver a concentrated form of the metalloproteinase to sites that have activating proteases, such as sites of inflammation, infection or cancerous growth. Meprins provide examples of novel ways of concentrating proteolytic activity at the cell surface and in the extracellular milieu, which may be critical to proteolytic function.     

Inter-familial relationships of the shorebirds (Aves: Charadriiformes) based on nuclear DNA sequence data

Background  

Phylogenetic hypotheses of higher-level relationships in the order Charadriiformes based on morphological data, partly disagree with those based on DNA-DNA hybridisation data. So far, these relationships have not been tested by analysis of DNA sequence data. Herein we utilize 1692 bp of aligned, nuclear DNA sequences obtained from 23 charadriiform species, representing 15 families. We also test earlier suggestions that bustards and sandgrouses may be nested with the charadriiforms. The data is analysed with methods based on the parsimony and maximum-likelihood criteria.     

(R)-2-(4-Phenylbutyl)dihydrobenzofuran derivatives as melatoninergic agents

(R)-2-(4-Phenylbutyl)dihydrobenzofuran derivatives (e.g., 3 and 4) were synthesized as novel melatoninergic ligands with significantly lower vasoconstrictive activity in vitro in the rat tail artery. Binding affinity assays were performed on cloned human MT1 and MT2 receptors stably expressed in NIH3T3 cells.