Overview of Human Salivary Glands: Highlights of Morphology and Developing Processes

Salivary glands are essential organs that produce and secrete saliva to the oral cavity. During gland morphogenesis, many developmental processes involve a series of coordinated movements and reciprocal interactions between the epithelium and mesenchyme that generate the ductal system and the secretory units. Recent studies have shown new findings about salivary gland development, particularly regarding lumen formation and expansion, with the involvement of apoptosis and cell polarization, respectively. Moreover, it has been observed that human minor salivary glands start forming earlier than previously published and that distinct apoptotic mediators can trigger duct lumen opening in humans. This review summarizes updated morphological and cellular features of human salivary glands and also explores new aspects of the human developmental process. Anat Rec, 300:1180–1188, 2017. © 2017 Wiley Periodicals, Inc.     

IgG4‐related sialadenitis and Sjögren's syndrome

IgG4‐related disease (IgG4‐RD) has emerged as a new entity in the last decade. It comprises numerous conditions previously thought to be unrelated. Macroscopically, these diseases cause diffuse organ swelling and formation of pseudotumorous masses. Histopathologically, they are characterized by a lymphoplasmacytic infiltrate with increased IgG4+ plasma cells and storiform fibrosis. Despite rapid progress within the last years, our knowledge on these conditions is still fragmented. To date, more than forty organs have been reported to be included in IgG4‐RD, and salivary gland involvement is amongst the most common organs affected [IgG4‐related sialadenitis (IgG4‐RS)]. Interestingly, IgG4‐RS shares commonalities with Sjögren's syndrome (SS), like glandular enlargement, sicca symptoms, arthralgias, hypergammaglobulinemia, hypocomplementemia, and circulating antinuclear antibodies. Nonetheless, they differ in that the incidence of anti‐Ro and anti‐La reactivity is not frequently found in patients with IgG4‐RS, their salivary glands are infiltrated by a large number of IgG4+ plasma cells and IgG4‐RS symptoms respond promptly to steroids. The aim of this review was to describe the clinical, serological, histopathological and pathophysiological aspects of IgG4‐RS in the context of IgG4‐RD and highlight the differences between IgG4‐RS and SS.     

HIF‐1α triggers long‐lasting glutamate excitotoxicity via system xc− in cerebral ischaemia–reperfusion

Hypoxia‐inducible factor 1α (HIF ‐1α) controls many genes involved in physiological and pathological processes. However, its roles in glutamatergic transmission and excitotoxicity are unclear. Here, we proposed that HIF ‐1α might contribute to glutamate‐mediated excitotoxicity during cerebral ischaemia–reperfusion (CIR ) and investigated its molecular mechanism. We showed that an HIF ‐1α conditional knockout mouse displayed an inhibition in CIR ‐induced elevation of extracellular glutamate and N ‐methyl‐d ‐aspartate receptor (NMDAR ) activation. By gene screening for glutamate transporters in cortical cells, we found that HIF ‐1α mainly regulates the cystine–glutamate transporter (system x_c^?) subunit xCT by directly binding to its promoter; xCT and its function are up‐regulated in the ischaemic brains of rodents and humans, and the effects lasted for several days. Genetic deletion of xCT in cortical cells of mice inhibits either oxygen glucose deprivation/reoxygenation (OGDR ) or CIR ‐mediated glutamate excitotoxicity in vitro and in vivo . Pharmaceutical inhibition of system x_c^? by a clinically approved anti‐cancer drug, sorafenib, improves infarct volume and functional outcome in rodents with CIR and its therapeutic window is at least 3 days. Taken together, these findings reveal that HIF ‐1α plays a role in CIR ‐induced glutamate excitotoxicity via the long‐lasting activation of system x_c^?‐dependent glutamate outflow and suggest that system x_c^? is a promising therapeutic target with an extended therapeutic window in stroke. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Impedance feedback control of microfluidic valves for reliable post processing combinatorial droplet injection

Droplet microfluidics has found use in many biological assay applications as a means of high-throughput sample processing. One of the challenges of the technology, however, is the ability to control and merge droplets on-demand as they flow through the microdevices. It is in the interest of developing lab-on-chip devices to be able to combinatorically program additive mixing steps for more complex multistep and multiplex assays. Existing technologies to merge droplets are either passive in nature or require highly predictable droplet movement for feedforward control, making them vulnerable to errors during high throughput operation. In this paper, we describe and demonstrate a microfluidic valve-based device for the purpose of combinatorial droplet injection at any stage in a multistep assay. Microfluidic valves are used to robustly control fluid flow, droplet generation, and droplet mixing in the device on-demand, while on-chip impedance measurements taken in real time are used as feedback to accurately time the droplet injections. The presented system is contrasted to attempts without feedback, and is shown to be 100% reliable over long durations. Additionally, content detection and discretionary injections are explored and successfully executed.     

Automatic whole brain tract‐based analysis using predefined tracts in a diffusion spectrum imaging template and an accurate registration strategy

Automated tract‐based analysis of diffusion MRI is an important tool for investigating tract integrity of the cerebral white matter. Current template‐based automatic analyses still lack a comprehensive list of tract atlas and an accurate registration method. In this study, tract‐based automatic analysis (TBAA) was developed to meet the demands. Seventy‐six major white matter tracts were reconstructed on a high‐quality diffusion spectrum imaging (DSI) template, and an advanced two‐step registration strategy was proposed by incorporating anatomical information of the gray matter from T1‐weighted images in addition to microstructural information of the white matter from diffusion‐weighted images. The automatic analysis was achieved by establishing a transformation between the DSI template and DSI dataset of the subject derived from the registration strategy. The tract coordinates in the template were transformed to native space in the individual's DSI dataset, and the microstructural properties of major tract bundles were sampled stepwise along the tract coordinates of the subject's DSI dataset. In a validation study of eight well‐known tracts, our results showed that TBAA had high geometric agreement with manual tracts in both deep and superficial parts but significantly smaller measurement variability than manual method in functional difference. Additionally, the feasibility of the method was demonstrated by showing tracts with altered microstructural properties in patients with schizophrenia. Fifteen major tract bundles were found to have significant differences after controlling the family‐wise error rate. In conclusion, the proposed TBAA method is potentially useful in brain‐wise investigations of white matter tracts, particularly for a large cohort study. Hum Brain Mapp 36:3441–3458, 2015. © 2015 Wiley Periodicals, Inc .     

Activated Human Valvular Interstitial Cells Sustain Interleukin-17 Production To Recruit Neutrophils in Infective Endocarditis

The mechanisms that underlie valvular inflammation in streptococcus-induced infective endocarditis (IE) remain unclear. We previously demonstrated that streptococcal glucosyltransferases (GTFs) can activate human heart valvular interstitial cells (VIC) to secrete interleukin-6 (IL-6), a cytokine involved in T helper 17 (Th17) cell differentiation. Here, we tested the hypothesis that activated VIC can enhance neutrophil infiltration through sustained IL-17 production, leading to valvular damage. To monitor cytokine and chemokine production, leukocyte recruitment, and the induction or expansion of CD4⁺ CD45RA⁻ CD25⁻ CCR6⁺ Th17 cells, primary human VIC were cultured in vitro and activated by GTFs. Serum cytokine levels were measured using an enzyme-linked immunosorbent assay (ELISA), and neutrophils and Th17 cells were detected by immunohistochemistry in infected valves from patients with IE. The expression of IL-21, IL-23, IL-17, and retinoic acid receptor-related orphan receptor C (Rorc) was upregulated in GTF-activated VIC, which may enhance the proliferation of memory Th17 cells in an IL-6-dependent manner. Many chemokines, including chemokine (C-X-C motif) ligand 1 (CXCL1), were upregulated in GTF-activated VIC, which might recruit neutrophils and CD4⁺ T cells. Moreover, CXCL1 production in VIC was induced in a dose-dependent manner by IL-17 to enhance neutrophil chemotaxis. CXCL1-expressing VIC and infiltrating neutrophils could be detected in infected valves, and serum concentrations of IL-17, IL-21, and IL-23 were increased in patients with IE compared to healthy donors. Furthermore, elevated serum IL-21 levels have been significantly associated with severe valvular damage, including rupture of chordae tendineae, in IE patients. Our findings suggest that VIC are activated by bacterial modulins to recruit neutrophils and that such activities might be further enhanced by the production of Th17-associated cytokines. Together, these factors can amplify the release of neutrophilic contents in situ, which might lead to severe valvular damage.     

Acute and long-term outcomes of intracoronary stenting in aorto-ostial, left anterior descending artery-ostial and nonostial stenoses

Percutaneous transluminal coronary angioplasty in ostial lesions is technically difficult and is associated with a lower procedural success rate, higher complication rate and restenosis rate as compared to nonostial lesions. The safety, feasibility, immediate and 6-month angiographic, and long-term clinical outcomes of stenting in aorto-ostial, left anterior descending artery (LAD)-ostial and nonostial stenoses, were retrospectively compared in 19 patients with 20 aorto-ostial lesions (group A), 97 with 97 LAD-ostial lesions (group B) and 1778 with 2242 nonostial lesions (group C). The major adverse cardiac events during hospitalization were similar among the three groups (p = 0.816). Twelve patients with 12 lesions in group A, 75 with 75 lesions in group B and 1384 with 1749 lesions in group C underwent a 6-month follow-up coronary angiography. There were no differences in acute gain (2.04 +/- 0.46 vs. 2.34 +/- 0.50 vs. 2.39 +/- 0.54 mm, respectively, p = 0.057) and net gain (0.89 +/- 1.02 vs. 1.26 +/- 1.08 vs. 1.34 +/- 0.76 mm, respectively, p = 0.105) among the three groups. Group B had a larger late loss than group A and C (1.15 +/- 1.01 vs. 1.22 +/- 0.76 vs. 1.04 +/- 0.65 mm, respectively, p = 0.048) and group A had a larger loss index than group B and C (0.59 +/- 0.50 vs. 0.52 +/- 0.31 vs. 0.48 +/- 0.29, respectively, p = 0.027). The binary restenosis rate among the three groups was 33%, 29% and 20%, respectively, (p = 0.072). Group B had higher restenotic rate as compared to group C (p = 0.036). During a long-term follow-up period of 42+/-21 months, major adverse cardiac events were similar among the three groups (15.8% vs. 25.8% vs. 20.1%, respectively, p = 0.362), but group B had a higher incidence of recurrent angina as compared to group C (17.5% vs. 10.9%, p = 0.039). The cardiac event-free survival rate, as determined by Kaplan-Meier analysis, was similar among the three groups (56% vs. 57% vs. 67%, respectively, p = 0.149); a borderline significance was noted as compared group B to group C (p = 0.051). In conclusion, stenting in aorto-ostial or LAD-ostial lesions is safe, feasible and has a similar acute result as compared to stenting in nonostial lesions; however, it still has a higher 6-month angiographic restenosis rate. LAD-ostial stenoses may have a less favorable long-term clinical outcome than nonostial stenoses.     

The synapsis event in the homologous pairing of DNAs: RecA recognizes and pairs less than one helical repeat of DNA.

A key step in homologous recombination is the alignment and pairing of homologous DNAs. The Escherichia coli RecA protein initiates pairing by binding to single-strand DNA, forming a helical nucleoprotein filament. We demonstrate that in the presence of the nonhydrolyzable ATP analogue adenosine 5'-[gamma-thio]triphosphate and ADP, RecA can pair a homologous oligonucleotide 15 bases long with a duplex DNA to yield synaptic complexes consisting of the oligonucleotide and duplex DNA stabilized by RecA. RecA can pair as few as eight bases of homology to form such synaptic complexes. The homologous DNAs remain paired to each other upon removal of RecA provided that the length of shared homology is at least 26 base pairs. Based on our findings and the work of others, we propose that in vitro, one helical turn of a RecA nucleoprotein filament containing approximately six RecA monomers and 15 bases of single-strand DNA is the functional unit sufficient to carry out the homology search.