Apical enzyme

Leptin, a highly conserved adipocyte-derived hormone, plays important roles in a variety of physiological processes, including the control of fat storage and metabolic status which are linked to food intake, energy homeostasis, and reproduction in all vertebrates. In the present study, we hypothesize that leptin is also present in various organs of the fresh water prawns, Macrobrachium rosenbergii. The existence and distribution of a leptin-like peptide in prawn tissues were verified by using Western blotting (WB) and immunohistochemical detection (ID) using primary antibody against human leptin...

The primary hepatocytes culture is still one of the main challenges in toxicology studies in the drug discovery process, development of in vitro models to study liver function, and cell-based therapies. Isolated hepatocytes display a rapid decline in viability and liver-specific functions including albumin production, conversion of ammonia to urea, and activity of the drug metabolizing enzymes. A number of methods have been developed in order to maintain hepatocytes in their highly differentiated state in vitro...

In plants and protists, dihydrofolate reductase (DHFR) and thymidylate synthase (TS) are part of a bifunctional enzyme (DRTS) that allows efficient recycling of the dihydrofolate resulting from TS activity. Arabidopsis thaliana possesses three DRTS genes, called AtDRTS1, AtDRTS2 and AtDRTS3, that are located downstream of three members of the sec14-like SFH gene family. In this study, a characterization of the AtDRTS genes identified alternatively spliced transcripts coding for AtDRTS isoforms which may account for monofunctional DHFR enzymes supporting pathways unrelated to DNA synthesis...

An emerging vision for toxicity testing in the 21st century foresees in vitro assays assuming the leading role in testing for chemical hazards, including testing for carcinogenicity. Toxicity will be determined by monitoring key steps in functionally validated molecular pathways, using tests designed to reveal chemically-induced perturbations that lead to adverse phenotypic endpoints in cultured human cells. Risk assessments would subsequently be derived from the causal in vitro endpoints and concentration vs...

INTRODUCTION: MicroRNA-335-5p has been reported to regulate osteogenic and chondrogenic differentiations of mesenchymal stem cells. The aim of this study was to explore the function and regulation mechanism of miR-335-5p in apical periodontitis (AP). METHODS: Total RNAs were extracted from human periodontal ligament fibroblasts (HPDLFs), 10 AP tissues, and 6 healthy periodontal ligament tissues using lysis buffer. Gene expression was detected using real-time polymerase chain reaction...

Plants are known for their capacity to regenerate the whole body through de novo formation of apical meristems from a mass of proliferating cells named callus. Exogenous cytokinin and auxin determine cell fate for the establishment of the stem cell niche, which is the vital step of shoot regeneration, but the underlying mechanisms remain unclear. Here we show that type-B ARABIDOPSIS RESPONSE REGULATORs (ARRs), critical components of cytokinin signaling, activate the transcription of WUSCHEL (WUS), which encodes a key regulator for maintaining stem cells...

Ceramides and complex sphingolipids with defined acyl-chain lengths play important roles in numerous cell processes. Six ceramide synthase isoenzymes (CerS1-6) are the key enzymes responsible for the production of the diversity of molecular species. In this study, we investigated the changes in sphingolipid metabolism during the differentiation of Madin-Darby Canine Kidney (MDCK) cells. By MALDI TOF TOF MS, we analyzed the molecular species of ceramide (Cer), glucosylceramide (GlcCer), lactosylceramide (LacCer) and sphingomyelin (SM) in non-differentiated and differentiated cells (cultured under hypertonicity)...

PURPOSE: We have shown previously that non-enzymatic nitration (NEN) of the extracellular matrix (ECM), which serves as a model of Bruch's membrane (BM) aging, has a profound effect on the behavior of the overlying retinal pigment epithelial (RPE) cells, including altered phagocytic ability, reduced cell adhesion, and inhibition of proliferation. We know that transplanted RPE monolayers will encounter a hostile sub-RPE environment, including age-related alterations in BM that may compromise cell function and survival...

The mechanisms that power the physiological events occuring in cilia, flagella and microvilli are of fundamental importance for the functions of these important and ubicuous organelles. The olfactory epithelium (OE) is mostly populated by ciliated olfactory sensory neurons (OSNs) and surrounding sustentacular cells (SCs) with apical microvilli. The only OSN dendrite extends to the surface forming a knob projecting several chemosensory cilia of approximately 50 x 0.2 μm, devoid of inner membranes embedded in a mucus layer...

SUMMARY: Takotsubo cardiomyopathy (TC) is an atypical, severe but reversible form of acute heart insufficiency. It typically presents with left ventricular failure, transient apical and mid-segments hypokinesis, absence of significant coronary stenosis and new electrographic abnormalities and/or elevation in serum cardiac enzymes. Although TC ('broken heart syndrome') has classically been associated with emotional trauma, evidence suggests that other precipitants might exist, including iatrogenic and thyroid-mediated forms...

Objectives: The early phase of orthodontic tooth movement involves acute inflammatory response that may induce bone resorption. The aim of this study was to localize and quantify cells in the periodontium expressing proinflammatory mediators during orthodontically induced periapical root resorption of the rat mandibular molars. Materials and methods: The levels of proinflammatory cytokines interleukin-1 (IL-1) α and β, tumor necrosis factor-α (TNF-α), inflammatory enzymes cyclooxygenase (COX) 1 and 2, and their product prostaglandin E2 (PGE2) in the root resorption site were compared to those in the corresponding area of the untreated periodontal ligament (PDL) of physiologically drifting teeth...

Aspartic proteases (Aps, EC3.4.23) are one of the 4 major mechanistic classes of proteolytic enzymes with the conserved motifs Asp-Thr/Ser-Gly (DT/SG) at the active site and are activated at acidic pH. In Arabidopsis, 69 genes were identified as coding putative aspartic proteinases. However, little is known about most of these enzymes. Recently, we characterized 2 novel Arabidopsis Aps genes, A36 and A39, which encode 2 putative GPI-anchored pollen-high-expressed Aps. a36 a39 mutants display significant abortion...

INTRODUCTION: This study was conducted to observe the immunohistochemical localization of high-mobility group box 1 (HMGB1) and its receptor, Toll-like receptor 4 (TRL4), in the development of periapical lesions induced in rats. The possible role of these molecules in the pathogenesis of periapical lesions was also explored. METHODS: Periapical lesions developed within 35 days after mandibular first molar pulp exposure in Wistar rats. The animals were randomly killed at 0, 7, 14, 21, 28, and 35 days after pulp exposure...

The shoot apical meristem (SAM) is a small population of stem cells that continuously generates organs and tissues. We will discuss here flower formation at the SAM, which involves a complex network of regulatory genes and signalling molecules. A major downstream target of this network is the extracellular matrix or cell wall, which is a local determinant for both growth rates and growth directions. We will discuss here a number of recent studies aimed at analysing the link between cell wall structure and molecular regulation...

Over the past few years, the role of intestinal alkaline phosphatase (IAP) as a crucial mucosal defence factor essential for maintaining gut homeostasis has been established. IAP is an important apical brush border enzyme expressed throughout the gastrointestinal tract and secreted both into the intestinal lumen and into the bloodstream. IAP exerts its effects through dephosphorylation of proinflammatory molecules including lipopolysaccharide (LPS), flagellin, and adenosine triphosphate (ATP) released from cells during stressful events...

The most extensively characterized human-derived cell line used in transcorneal permeability studies, in terms of passive transcellular and paracellular transport, transporter expression and metabolic enzymes, is the immortalized human corneal epithelial cell line (HCE-T). The purpose of this study is to describe the changes in the HCE-T barrier phenotype in vitro when valid cultivation conditions, in accordance with the standardized HCE-T cell-based model protocol, were employed. Evaluation of the structural and functional barrier properties revealed two different HCE-T barrier phenotypes, depending on the polycarbonate membrane pore size...

Ile-Pro-Pro (IPP) and Leu-Lys-Pro (LKP) are food-derived antihypertensive peptides which inhibit angiotensin-converting enzyme (ACE) and may have potential to attenuate hypertension. There is debate over their mechanism of uptake across small intestinal epithelia, but paracellular and PepT1 carrier-mediated uptake are thought to be important routes. The aim of this study was to determine their routes of intestinal permeability using in vitro, ex vivo and in vivo intestinal models. The presence of an apical side pH of 6...

Daily, the retinal pigment epithelium (RPE) ingests a bolus of lipid and protein in the form of phagocytized photoreceptor outer segments (OS). The RPE, like the liver, expresses enzymes required for fatty acid oxidation and ketogenesis. This suggests that these pathways play a role in the disposal of lipids from ingested OS, as well as providing a mechanism for recycling metabolic intermediates back to the outer retina. In this study, we examined whether OS phagocytosis was linked to ketogenesis. We found increased levels of β-hydroxybutyrate (β-HB) in the apical medium following ingestion of OS by human fetal RPE and ARPE19 cells cultured on Transwell inserts...

The transport behavior and absorption mechanism of Ala-His-Leu-Leu (AHLL) intestinal absorption in Caco-2 cell monolayers were clarified systemically. The safe absorptive concentration of AHLL was 200 μg/mL, which was determined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. The permeation of AHLL was concentration dependent in a bidirectional transfer and reached a plateau at 90 min. The efflux ratio was above 0.5, suggesting that AHLL was absorbed by both active transport and passive diffusion...

BACKGROUND: Different studies have implicated the exposure to systemic conditions in the aetiology of cardiovascular diseases like chronic inflammation including chronic periodontitis. AIM: The present study has been conducted to examine whether biomarker sTNF-R was elevated in apical periodontitis as sTNF-R is a systemic marker of inflammation and has been identified as risk factors for cardiovascular diseases. MATERIAL AND METHODS: sTNF-R levels were measured in 52 patients with apical periodontitis (M:F::25:27), aged 20-45 years and in 20 control patients without periodontitis (M:F::10:10, aged 20-48 years)...