On the domain of singular traces

The question whether an operator belongs to the domain of some singular trace is addressed, together with the dual question whether an operator does not belong to the domain of some singular trace. We show that the answers are positive in general, namely for any (compact, infinite rank) positive operator A we exhibit two singular traces, the first being zero and the second being infinite on A. However, if we assume that the singular traces are generated by a "regular" operator, the answers change, namely such traces always vanish on trace-class, non singularly traceable operators and are always infinite on non trace-class, non singularly traceable operators. These results are achieved on a general semifinite factor, and make use of a new characterization of singular traceability (cf. math.OA/0202108).Comment: 7 pages, LaTeX. Minor corrections, to appear on the International Journal of Mathematic

Dynamics of the melatonin MT1 receptor in the rat parotid gland upon melatonin administration

Our recent ultrastructural study of human parotid glands revealed that the melatonin receptors, MT1 and MT2, are localised in the plasma cell membranes of acinar and ductal cells but also, and intriguingly, predominantly in acinar secretory granules, giving rise to the working hypothesis that secretory granules are a part of a transcytotic transport system for melatonin. To put this hypothesis to the test in rat parotid glands, anaesthetised animals were exposed to a high melatonin dose (3 mg/kg per hour), infused intravenously over two hours and aiming to stimulate a glandular melatonin-receptor-dependent intracellular transport system, if any. Thirty minutes later, the right parotids were removed. Pre-stimulation, left parotid gland tissue was removed to serve as (untreated) controls. Gland tissues were processed for the gold post-embedding technique and for western blot analysis. In untreated glands, on transmission electron microscope images, melatonin receptors displayed a distribution pattern similar to that in human parotids, i.e. here, too, the receptors were principally associated with the acinar secretory granules. In melatonin- treated glands, the number of granules associated with the MT1 receptor was twice that in untreated glands, despite the same total granule number in the two glands. Moreover, the density of gold particles showing MT1-receptor immunoreactivity associated with granules in melatonin-treated glands was 2.5 times that in untreated glands. The number of MT1 receptors associated with the granule membrane was about three times higher in melatonin-treated glands than in untreated glands, while the number of MT1 receptors inside the granules was about twice that in untreated glands. The immunoblotting of membrane-enriched samples showed that the MT1-receptor expression was about three times that of untreated glands. When it came to the MT2 receptor, no changes were observed. Melatonin itself thus exerts dynamic effects on its MT1 receptor, which may reflect an adaptive receptor-linked carrier system for melatonin, delivering - upon gland stimulation - melatonin to the saliva by exocytosis

Prostate-specific antigen: An unfamiliar protein in the human salivary glands

Objectives: The presence of prostate-specific antigen (PSA) in saliva and salivary glands has been reported. Nevertheless, its release pathway in these glands remains to be elucidated. Here, we showed PSA subcellular distribution focusing on its plausible route in human salivary parenchyma. Materials and Methods: Sections of parotid and submandibular glands were subjected to the immunohistochemical demonstration of PSA by the streptavidin–biotin method revealed by alkaline phosphatase. Moreover, ultrathin sections were collected on nickel grids and processed for immunocytochemical analysis, to visualize the intracellular distribution pattern of PSA through the observation by transmission electron microscopy. Results: By immunohistochemistry, in both parotid and submandibular glands PSA expression was detected in serous secretory acini and striated ducts. By immunocytochemistry, immunoreactivity was retrieved in the cytoplasmic compartment of acinar and ductal cells, often associated with small cytoplasmic vesicles. PSA labeling appeared also on rough endoplasmic reticulum and in the acini's lumen. A negligible PSA labeling appeared in most of the secretory granules of both glands. Conclusions: Our findings clearly support that human parotid and submandibular glands are involved in PSA secretion. Moreover, based on the immunoreactivity pattern, its release in oral cavity would probably occur by minor regulated secretory or constitutive-like secretory pathways

Ultrastructural evidence of a secretory role for melatonin in the human parotid gland

In vivo animal studies show that pentagastrin, cholecystokinin and melatonin cause the secretion and synthesis of salivary proteins. Melatonin occurs in large amounts in the gut and is released into the blood on food intake. In vitro experiments suggest that pentagastrin exerts secretory activity in human salivary glands, as judged by ultrastructural changes, reflecting secretion, and an actual protein output. Currently, it is hypothesised that melatonin induces secretory exocytotic events in the human parotid gland. Human parotid tissues were exposed to a high single concentration of melatonin in vitro, processed for high resolution scanning electron microscopy and then assessed morphometrically with the emphasis on the membrane of the intercellular canaliculi, a site of protein secretion. Compared with controls and in terms of density, the melatonin-exposed parotid tissues displayed increases in protrusions (signalling anchored granules) and microbuds (signalling membrane recycling and/or vesicle secretion) and decreases in microvilli (signalling cytoskeletal re-arrangement related to exocytosis), phenomena abolished or very largely reduced by the melatonin receptor blocker, luzindole. In conclusion, acinar serous cells of parotid tissue displayed in vitro exocytotic activity to melatonin, signalling protein secretion. Whether, under physiological conditions, melatonin influences the secretion of human parotid glands remains to be explored, however

Cluster Approximation for the Farey Fraction Spin Chain

We consider the Farey fraction spin chain in an external field $h$. Utilising ideas from dynamical systems, the free energy of the model is derived by means of an effective cluster energy approximation. This approximation is valid for divergent cluster sizes, and hence appropriate for the discussion of the magnetizing transition. We calculate the phase boundaries and the scaling of the free energy. At $h=0$ we reproduce the rigorously known asymptotic temperature dependence of the free energy. For $h \ne 0$, our results are largely consistent with those found previously using mean field theory and renormalization group arguments.Comment: 17 pages, 3 figure

The human major sublingual gland and its neuropeptidergic and nitrergic innervations

Background: What textbooks usually call the sublingual gland in humans is in reality a tissue mass of two types of salivary glands, the anteriorly located consisting of a cluster of minor sublingual glands and the posteriorly located major sublingual gland with its outlet via Bartholin's duct. Only recently, the adrenergic and cholinergic innervations of the major sublingual gland was reported, while information regarding the neuropeptidergic and nitrergic innervations is still lacking. Methods: Bioptic and autoptic specimens of the human major sublingual gland were examined by means of immunohistochemistry for the presence of vasoactive intestinal peptide (VIP)-, neuropeptide Y (NPY)-, substance P (SP)-, calcitonin gene related-peptide (CGRP)-, and neuronal nitric oxide synthase (nNOS)-labeled neuronal structures. Results: As to the neuropeptidergic innervation of secretory cells (here in the form of mucous tubular and seromucous cells), the findings showed many VIP-containing nerves, few NPY- and SP-containing nerves and a lack of CGRP-labeled nerves. As to the neuropeptidergic innervation of vessels, the number of VIP-containing nerves was modest, while, of the other neuropeptide-containing nerves under study, only few (SP and CGRP) to very few (NPY) nerves were observed. As to the nitrergic innervation, nNOS-containing nerves were very few close to secretory cells and even absent around vessels. Conclusion: The various innervation patterns may suggest potential transmission mechanisms involved in secretory and vascular responses of the major sublingual gland

Genetical stability and osteogenic ability of mesenchimal stem cells on demineralized bone matrices

Journal of Osseointegration Volume 7, Issue 1, 1 March 2015, Pages 2-7 Open Access Genetical stability and osteogenic ability of mesenchimal stem cells on demineralized bone matrices (Article) Pozzuoli, A.a, Gardin, C.b, Aldegheri, R.a, Bressan, E.c, Isola, M.d, Calvo-Guirado, J.L.e, Biz, C.a, Arrigoni, P.a, Feroni, L.b, Zavan, B.b a Department of Surgical,Oncological and Gastroenterological Sciences, University of Padua, Padua, Italy b Department of Biomedical Sciences, University of Padua, Padua, Italy c Department of Neurosciences, University of Padua, Padua, Italy d Department of Animal Medicine, Production and Health (MAPS), Italy e Department of General Dentistry, Faculty of Medicine and Dentistry, University of Murcia, Murcia, Spain Hide additional affiliations View references (44) Abstract Aim: Tissue engineering is a rapidly expanding field with regard to the use of biomaterials and stem cells in the orthopedic surgery. Many experimental studies have been done to understand the best characteristics of cells, materials and laboratory methods for safe clinical applications. The aim of this study was to compare the ability of 2 different human demineralized bone matrices (DBMs), the one enriched and the other not enriched with hyaluronic acid, to stimulate in vitro the proliferation and the osteogenic differentiation of human adipose-derived stem cells (ADSCs) seeded onto an osteoconductive scaffold. Materials and Methods: ADSCs were isolated, by enzymatic digestion, from abdominal adipose tissue of 5 patients undergoing cosmetic lipoaspiration surgery. ADSCs were then seeded onto a 3D scaffold in the presence of the two different osteoinductive matrices of human demineralized bone and evaluated for proliferation and osteogenic differentiation. The safety of the methods was verified using array-Comparative Genomic Hybridization (array-CGH). Results: ADSCs were able to differentiate in osteogenic sense. Both DBMs showed the ability to induce osteogenic differentiation of the cells. Conclusion: array-CGH showed no changes at genome level, thus confirming the safety of materials and method