Network of telocytes in the temporomandibular joint disc of rats

The phenotypes of the temporomandibular joint (TMJ) disc cells range from fibroblasts to chondrocytes. There are relatively few reported studies using transmission electron microscopy (TEM) to determine the ultrastructural features of these cells. It was hypothesized that at least a subpopulation of TMJ stromal cells could be represented by the telocytes, cells with telopodes. In this regard a TEM study was performed on rat TMJ samples. Collagen-embedded networks were found built-up by cells with telopodes with subplasmalemmal caveolae, moderate content in matrix secretory organelles and well-represented intermediate filaments. Appositions of cell bodies were found. Prolongations of such cells were closely related to nerves and microvessels. Our study indicates that the TMJ disc attachment seems equipped with telocytes capable of stromal signaling. However, further studies are needed to assess whether the telocytes belong to a renewed cell population derived from circulating precursors.     

The Mandibular Ridge Oral Mucosa Model of Stromal Influences on the Endothelial Tip Cells: An Immunohistochemical and TEM Study

This study aimed to evaluate by immunohistochemistry and transmission electron microscopy (TEM) the morphological features of the oral mucosa endothelial tip cells (ETCs) and to determine the immune and ultrastructural patterns of the stromal nonimmune cells which could influence healing processes. Immune labeling was performed on bioptic samples obtained from six edentulous patients undergoing surgery for dental implants placement; three normal samples were collected from patients prior to the extraction of the third mandibular molar. The antibodies were tested for CD34, CD117(c‐kit), platelet derived growth factor receptor‐alpha (PDGFR‐α), Mast Cell Tryptase, CD44, vimentin, CD45, CD105, alpha‐smooth muscle actin, FGF2, Ki67. In light microscopy, while stromal cells (StrCs) of the reparatory and normal oral mucosa, with a fibroblastic appearance, were found positive for a CD34/CD44/CD45/CD105/PDGFR‐α/vimentin immune phenotype, the CD117/c‐kit labeling led to a positive stromal reaction only in the reparatory mucosa. In TEM, non‐immune StrCs presenting particular ultrastructural features were identified as circulating fibrocytes (CFCs). Within the lamina propria CFCs were in close contact with ETCs. Long processes of the ETCs were moniliform, and hook‐like collaterals were arising from the dilated segments, suggestive for a different stage migration. Maintenance and healing of oral mucosa are so supported by extensive processes of angiogenesis, guided by ETCs that, in turn, are influenced by the CFCs that populate the stromal compartment both in normal and reparatory states. Therefore, CFCs could be targeted by specific therapies, with pro‐ or anti‐angiogenic purposes. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.     

Evaluation of cardiovascular events and progression to end-stage renal disease in patients with dyslipidemia and chronic kidney disease from the North-Eastern area of Romania

International Urology and Nephrology - The aim of this prospective cohort study was: to identify the association between different biomarkers [proprotein convertase subtilisin/kexin 9-PCSK9,...     

Lipid,blood pressure and kidney update 2013

The year 2013 proved to be very exciting as far as landmark trials and new guidelines in the field of lipid disorders, blood pressure and kidney diseases. Among these are the International Atherosclerosis Society Global Recommendations for the Management of Dyslipidemia, European Society of Cardiology (ESC)/European Society of Hypertension Guidelines for the Management of Arterial Hypertension, American Diabetes Association Clinical Practice Recommendations, the Kidney Disease: Improving Global Outcomes Clinical Practice Guidelines for Managing Dyslipidemias in Chronic Kidney Disease (CKD) Patients, the American College of Cardiology/American Heart Association Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults, the Joint National Committee Expert Panel (JNC 8) Evidence-Based Guideline for the Management of High Blood Pressure in Adults, the American Society of Hypertension/International Society of Hypertension Clinical Practice Guidelines for the Management of Hypertension in the Community, the American College of Physicians Clinical Practice Guideline on Screening, Monitoring, and Treatment of Stage 1–3 CKD and many important trials presented among others during the ESC Annual Congress in Amsterdam and the American Society of Nephrology Annual Meeting—Kidney Week in Atlanta, GA. The paper is an attempt to summarize the most important events and reports in the mentioned areas in the passing year.     

SAC phosphoinositide phosphatases at the tonoplast mediate vacuolar function in Arabidopsis

Phosphatidylinositol (PtdIns) is a structural phospholipid that can be phosphorylated into various lipid signaling molecules, designated polyphosphoinositides (PPIs). The reversible phosphorylation of PPIs on the 3, 4, or 5 position of inositol is performed by a set of organelle-specific kinases and phosphatases, and the characteristic head groups make these molecules ideal for regulating biological processes in time and space. In yeast and mammals, PtdIns3P and PtdIns(3,5)P₂ play crucial roles in trafficking toward the lytic compartments, whereas the role in plants is not yet fully understood. Here we identified the role of a land plant-specific subgroup of PPI phosphatases, the suppressor of actin 2 (SAC2) to SAC5, during vacuolar trafficking and morphogenesis in Arabidopsis thaliana. SAC2–SAC5 localize to the tonoplast along with PtdIns3P, the presumable product of their activity. In SAC gain- and loss-of-function mutants, the levels of PtdIns monophosphates and bisphosphates were changed, with opposite effects on the morphology of storage and lytic vacuoles, and the trafficking toward the vacuoles was defective. Moreover, multiple sac knockout mutants had an increased number of smaller storage and lytic vacuoles, whereas extralarge vacuoles were observed in the overexpression lines, correlating with various growth and developmental defects. The fragmented vacuolar phenotype of sac mutants could be mimicked by treating wild-type seedlings with PtdIns(3,5)P₂, corroborating that this PPI is important for vacuole morphology. Taken together, these results provide evidence that PPIs, together with their metabolic enzymes SAC2–SAC5, are crucial for vacuolar trafficking and for vacuolar morphology and function in plants.Polyphosphoinositides (PPIs) are a class of signaling membrane lipids, comprising the phosphorylated products of phosphatidylinositol (PtdIns). PPIs perform a dual function as scaffolding signals and precursors for other molecular messengers, which, together with their specific distribution at different intracellular membranes, makes PPIs important mediators of a wide variety of cellular processes, such as membrane trafficking and homeostasis, cytoskeleton organization, nuclear signaling, and stress responses (1–5). The metabolism of PPIs is regulated by specific kinases, phosphatases, and phospholipases to tightly control the concentration and intracellular localization of different lipid pools (2, 6, 7).In yeast, two phosphoinositide (PI) types, PtdIns3P and PtdIns(3,5)P₂, and their interconversion have been shown to play crucial roles in trafficking toward the vacuole, regulation of vacuolar pH, and vacuolar membrane fusion and fission (8–11). In yeast and mammals, production and degradation of PtdIns(3,5)P₂ involve the PtdIns3P 5-kinase Fab1p/PIKfyve and the antagonistic phosphatase factor-induced gene/suppressor of actin 3 (Fig4/Sac3), respectively (8, 12–14). Impairment of genes implicated in PtdIns(3,5)P₂ metabolism has deleterious consequences in yeast, plants, and mammals (8, 15–19), demonstrating an essential function of this minor phospholipid. Recent observations also hint at a role for PPIs in plant vacuoles (18–20), but the data are scarce and remain inconclusive.Advances in deciphering various cellular roles of PIs include insights into the phosphatases responsible for hydrolyzing PPIs. A group of phosphatases, designated suppressor of actin (SAC) domain phosphatases, has been identified in lower eukaryotes, mammals, and plants (21). Whereas yeast and humans have only five genes harboring the SAC domain, the genome of the model plant Arabidopsis thaliana contains nine genes, of which some have been functionally characterized and demonstrated to be involved in the regulation of stress responses (22–24), polarized root hair expansion (3), or cell wall formation (25).Here we show that the functionally uncharacterized group of Arabidopsis SAC2–SAC5 proteins that is orthologous to the yeast Fig4p is involved in PPI metabolism. SAC2–SAC5 localize along with PtdIns3P to the tonoplast and maintain the morphology of storage and lytic vacuoles. Our results demonstrate the crucial role of PPIs and SAC domain phosphatases in the function and morphology of vacuoles in plants.     

Quiescent satellite glial cells of the adult trigeminal ganglion

Sensory ganglia comprise functional units built up by neurons and satellite glial cells (SGCs). In animal species there was proven the presence of neuronoglial progenitor cells in adult samples. Such neural crest-derived progenitors were found in immunohistochemistry (IHC). These findings were not previously documented in transmission electron microscopy (TEM). It was thus aimed to assess in TEM if cells of the human adult trigeminal ganglion indeed have ultrastructural features to qualify for a progenitor, or quiescent phenotype. Trigeminal ganglia were obtained from fifteen adult donor cadavers. In TEM, cells with heterochromatic nuclei, a pancytoplasmic content of free ribosomes, few perinuclear mitochondria, poor developed endoplasmic reticulum, lack of Golgi complexes and membrane trafficking specializations, were found included in the neuronal envelopes built-up by SGCs. The ultrastructural pattern was strongly suggestive for these cells being quiescent progenitors. However, further experiments should correlate the morphologic and immune phenotypes of such cells.     

Critical Review: What Cell Types Are the Lung Telocytes?

Telocytes (TCs) are stromal cells defined by peculiar long, thin, moniliform prolongations known as telopodes. When isolated, their morphology often lacks the specificity for the proper definition of a particular cell type. Recent studies have linked TCs with different functions and different cell lineages. Although some authors have studied pulmonary TCs, their research has important limitations that we will attempt to summarize in this article. We will focus our analysis on the following: the culture methods used to study them, the lack of proper discrimination of TCs from lymphatic endothelial cells (LECs), whose ultrastructures are very similar, and the immune phenotype of TCs, which may appear in other cell types such as those related to the endothelial lineage or stem/progenitor cells. In conclusion, the cellular diagnosis of lung TCs should be considered with caution until properly designed studies can positively identify these cells and differentiate them from other cell types such as LECs and stem/progenitor cells. Anat Rec, 303:1280–1292, 2020. © 2019 American Association for Anatomy     

Changes in arterial stiffness following dialysis in relation to overhydration and to endothelial function

Introduction

Cardiovascular (CV) morbidity and mortality are greatly enhanced in patients with chronic kidney disease, partly due to increased arterial stiffness.

Material and method

The study included 63 stable HD patients. Stiffness parameters were evaluated by applanation tonometry before the mid-week HD sessions. Pre-HD bioimpedance parameters were measured. A phase angle <six degrees was previously reported as abnormal, reflecting extracellular overhydration. Fluid status was evaluated echocardiographic by measuring the inferior vena cava (IVC) diameter. Endothelium-dependent and endothelium-independent vascular reactivity were assessed by changes in Alx following sublingual nitroglycerin and inhaled salbutamol.

Results

PWV directly correlated with patients?? age and dialysis vintage. Patients with a phase angle <6°, were significantly overhydrated (larger IVC, increased ECW, and lower ICW), had stiffer arteries and greater left ventricle mass (LVM), compared with those with a phase angle >6°. Overhydration increases arterial stiffness, but has no influence on either EID or ED vascular reactivity.

Conclusion

In hemodialysis, volume overload is an important contributor to increased arterial stiffness and modifies cardiovascular status especially by LV hypertrophy. Achieving normohydration may significantly ameliorate cardiac abnormalities and arterial stiffness and may impact major clinical events and CV mortality.     

Aquaporin 1 expression in human temporomandibular disc

Aquaporins (AQPs) are a family of hydrophobic membrane channel proteins. The expression of several AQP isoforms has been investigated in different human tissues, including the orofacial region. However, information on the role and localization of AQP1 in joints is limited, and no data are available on aquaporins in the normal temporomandibular joint (TMJ) disc. Sixteen human TMJ discs without degenerative changes were taken from fresh cadavers to investigate the presence and distribution of AQP1 by immunohistochemistry. The aim of the study was to gain additional insights into the biomolecular composition of aquaporins and their role in homeostasis of the TMJ. Porcine TMJ discs were also studied by Western blotting for comparison. Scattered AQP1 immunoexpression was detected in human disc cells, documenting its constitutive expression, but differences amongst the three disc regions were not significant. AQP1 expression was demonstrated in porcine TMJ disc by Western blotting. Our findings suggest that AQP1 is normally expressed in the TMJ disc and confirm a role for it in the maintenance of TMJ homeostasis. Further studies are needed to elucidate expression patterns of aquaporins in diseased TMJ discs.     

Immunolocalization and expression of lubricin in the bilaminar zone of the human temporomandibular joint disc

Lubricin, which is a boundary joint lubricant, was investigated immunohistochemically in the bilaminar zone (BZ) of the human temporomandibular joint (TMJ), without any degenerative changes. Immunohistochemistry for lubricin detection was carried out on 33 TMJ discs obtained from 17 cadavers. Sections were incubated with diluted rabbit polyclonal anti-lubricin antibody and scored according to the percentage of lubricin immunopositive cells. Three different TMJ disc tissue compartments were analyzed, namely: the upper lamina, the inferior lamina and the loose connective tissue in the space between the laminae. The Mann-Whitney U test was used to compare protein expression (lubricin) among disc specimens’ regions. Staining was noted within the TMJ disc cell populations in every disc tissue sample, with almost every cell immunolabeled by the lubricin antibody. The number of disc cells immunolabeled was almost the same in the 3 bilaminar zone regions. Positive extracellular matrix staining was also seen. The results of the present study suggest that lubricin is expressed in the TMJ disc bilaminar zone. Lubricin may have a role in normal disc posterior attachment physiology through the prevention of cellular adhesion as well as providing lubrication during normal bilaminar zone function.