Matrix metalloproteinases in subjects with type 1 diabetes

<p>Abstract</p> <p>Background</p> <p>Nephropathy is serious complication of diabetes. We have previously shown that level of the proteoglycan syndecan-1 in blood is associated with ultrastructural kidney changes in young persons with type 1 diabetes. Dysregulation of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) may contribute to the development of nephropathy. The aim of this study was to investigate if the levels of MMPs in blood samples are potential markers of early nephropathy in type 1 diabetes.</p> <p>Methods</p> <p>Blood samples were collected from type 1 diabetes patients after 11 years of diabetes (n = 15) and healthy volunteers (n = 12) and stored at ÷80°C until measurement. Levels and activities of serum MMP-2, MMP-9, TIMP-1 and TIMP- 2 were analyzed and compared to those of control individuals using ELISA, SDS-PAGE gelatin zymography, and Western blot analysis.</p> <p>Results</p> <p>The serum levels of both MMP-9 and MMP-2 were significantly higher in subjects with type 1 diabetes, compared to controls (p = 0.016 and p = 0.008 respectively). Western blotting revealed no differences between the two groups in the levels of TIMP-1 or TIMP-2, respectively.</p> <p>Conclusion</p> <p>Our MMP analysis of serum from a limited number of patients with type 1 diabetes suggest that such analysis is potentially useful as markers in studies of people at risk of progression to chronic kidney disease.</p

Comparative analysis of homology models of the Ah receptor ligand binding domain: Verification of structure-function predictions by site-directed mutagenesis of a nonfunctional receptor

The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor that mediates the biological and toxic effects of a wide variety of structurally diverse chemicals, including the toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). While significant interspecies differences in AHR ligand binding specificity, selectivity, and response have been observed, the structural determinants responsible for those differences have not been determined, and homology models of the AHR ligand-binding domain (LBD) are available for only a few species. Here we describe the development and comparative analysis of homology models of the LBD of 16 AHRs from 12 mammalian and nonmammalian species and identify the specific residues contained within their ligand binding cavities. The ligand-binding cavity of the fish AHR exhibits differences from those of mammalian and avian AHRs, suggesting a slightly different TCDD binding mode. Comparison of the internal cavity in the LBD model of zebrafish (zf) AHR2, which binds TCDD with high affinity, to that of zfAHR1a, which does not bind TCDD, revealed that the latter has a dramatically shortened binding cavity due to the side chains of three residues (Tyr296, Thr386, and His388) that reduce the amount of internal space available to TCDD. Mutagenesis of two of these residues in zfAHR1a to those present in zfAHR2 (Y296H and T386A) restored the ability of zfAHR1a to bind TCDD and to exhibit TCDD-dependent binding to DNA. These results demonstrate the importance of these two amino acids and highlight the predictive potential of comparative analysis of homology models from diverse species. The availability of these AHR LBD homology models will facilitate in-depth comparative studies of AHR ligand binding and ligand-dependent AHR activation and provide a novel avenue for examining species-specific differences in AHR responsiveness. © 2013 American Chemical Society

Aging of the mammalian gastrointestinal tract: a complex organ system

Gastrointestinal disorders are a major cause of morbidity in the elderly population. The gastrointestinal tract is the most complex organ system; its diverse cells perform a range of functions essential to life, not only secretion, digestion, absorption and excretion, but also, very importantly, defence. The gastrointestinal tract acts not only as a barrier to harmful materials and pathogens but also contains the vast number of beneficial bacterial populations that make up the microbiota. Communication between the cells of the gastrointestinal tract and the central nervous and endocrine systems modifies behaviour; the organisms of the microbiota also contribute to this brain–gut–enteric microbiota axis. Age-related physiological changes in the gut are not only common, but also variable, and likely to be influenced by external factors as well as intrinsic aging of the cells involved. The cellular and molecular changes exhibited by the aging gut cells also vary. Aging intestinal smooth muscle cells exhibit a number of changes in the signalling pathways that regulate contraction. There is some evidence for age-associated degeneration of neurons and glia of the enteric nervous system, although enteric neuronal losses are likely not to be nearly as extensive as previously believed. Aging enteric neurons have been shown to exhibit a senescence-associated phenotype. Epithelial stem cells exhibit increased mitochondrial mutation in aging that affects their progeny in the mucosal epithelium. Changes to the microbiota and intestinal immune system during aging are likely to contribute to wider aging of the organism and are increasingly important areas of analysis. How changes of the different cell types of the gut during aging affect the numerous cellular interactions that are essential for normal gut functions will be important areas for future aging research

Structure and Function of the Hair Cell Ribbon Synapse

Faithful information transfer at the hair cell afferent synapse requires synaptic transmission to be both reliable and temporally precise. The release of neurotransmitter must exhibit both rapid on and off kinetics to accurately follow acoustic stimuli with a periodicity of 1 ms or less. To ensure such remarkable temporal fidelity, the cochlear hair cell afferent synapse undoubtedly relies on unique cellular and molecular specializations. While the electron microscopy hallmark of the hair cell afferent synapse — the electron-dense synaptic ribbon or synaptic body — has been recognized for decades, dissection of the synapse’s molecular make-up has only just begun. Recent cell physiology studies have added important insights into the synaptic mechanisms underlying fidelity and reliability of sound coding. The presence of the synaptic ribbon links afferent synapses of cochlear and vestibular hair cells to photoreceptors and bipolar neurons of the retina. This review focuses on major advances in understanding the hair cell afferent synapse molecular anatomy and function that have been achieved during the past years

Functional immune responses against SARS-CoV-2 variants of concern after fourth COVID-19 vaccine dose or infection in patients with blood cancer

Patients with blood cancer continue to have a greater risk of inadequate immune responses following three COVID-19 vaccine doses and risk of severe COVID-19 disease. In the context of the CAPTURE study (NCT03226886), we report immune responses in 80 patients with blood cancer who received a fourth dose of BNT162b2. We measured neutralizing antibody titers (NAbTs) using a live virus microneutralization assay against wild-type (WT), Delta, and Omicron BA.1 and BA.2 and T cell responses against WT and Omicron BA.1 using an activation-induced marker (AIM) assay. The proportion of patients with detectable NAb titers and T cell responses after the fourth vaccine dose increased compared with that after the third vaccine dose. Patients who received B cell-depleting therapies within the 12 months before vaccination have the greatest risk of not having detectable NAbT. In addition, we report immune responses in 57 patients with breakthrough infections after vaccination

Active zone proteins are dynamically associated with synaptic ribbons in rat pinealocytes

Synaptic ribbons (SRs) are prominent organelles that are abundant in the ribbon synapses of sensory neurons where they represent a specialization of the cytomatrix at the active zone (CAZ). SRs occur not only in neurons, but also in neuroendocrine pinealocytes where their function is still obscure. In this study, we report that pinealocyte SRs are associated with CAZ proteins such as Bassoon, Piccolo, CtBP1, Munc13–1, and the motorprotein KIF3A and, therefore, consist of a protein complex that resembles the ribbon complex of retinal and other sensory ribbon synapses. The pinealocyte ribbon complex is biochemically dynamic. Its protein composition changes in favor of Bassoon, Piccolo, and Munc13–1 at night and in favor of KIF3A during the day, whereas CtBP1 is equally present during the night and day. The diurnal dynamics of the ribbon complex persist under constant darkness and decrease after stimulus deprivation of the pineal gland by constant light. Our findings indicate that neuroendocrine pinealocytes possess a protein complex that resembles the CAZ of ribbon synapses in sensory organs and whose dynamics are under circadian regulation