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AimsOur laboratory has found that lysophosphatidic acid (LPA) and its cognate receptors [LPARs, (LPA1–6)] expressed by human gingival fibroblasts (GF) and periodontal ligament fibroblasts (PDLF) play key roles in oral fibroblast homeostasis and are implicated in the inflammation seen in periodontal disease. We have reported that PDLF express LPA1 and LPA3; however, information on the gross topographic distribution of LPARs in the periodontal ligament (PDL) was lacking, and therefore, we developed a simple method forin situlabeling of LPARs in the PDL of extracted teeth.Materials and methodsSectioning or grinding thin sections of demineralized or native teeth and periodontium have long been the standard methodologies used to assess biomarker distribution in the PDL; however, we modified traditional immunohistochemical labeling and used whole teeth with fixed, solvent permeabilized PDLs.ResultsLPA1 and LPA3 were specifically labeled in the PDL and could be visualized at both the macroand micro-levels.ConclusionThis technique effectively labeled LPARs, and it can serve as a basis for thein situvisualization of other biomolecules expressed in the PDL.Clinical SignificanceThe ability to observe PDL LPAR distribution at the macro-level complements the microscopic data, and it is useful for detecting and documenting molecular changes in the PDL/PDLF that were brought about by age, experimental treatments, or pathologies like periodontal disease.How to cite this articleCerutis DR, Headen KV, Ogunleye AO, Williams DE. A High-resolution Immunohistochemical Method for studying Receptor Expression on the Periodontal Ligament of Whole-mount Human Tooth Roots. Int J Experiment Dent Sci 2016;5(2):99-103.

Purpose: The aim of this study was to evaluate the surface characteristics and gingival fibroblast adhesion of disks composed of implant and abutment materials following brief and repeated instrumentation with instruments commonly used in procedures for implant maintenance, stage-two implant surgery, and periimplantitis treatment. Materials and Methods: One hundred twenty disks (40 titanium, 40 titaniumzirconium, 40 zirconia) were grouped into treatment categories of instrumentation by plastic curette, titanium curette, diode microlaser, rotary titanium brush, and no treatment. Twenty strokes were applied to half of the disks in the plastic and titanium curette treatment categories, while half of the disks received 100 strokes each to simulate implant maintenance occurring on a repetitive basis. Following analysis of the disks by optical laser profilometry, disks were cultured with human gingival fibroblasts. Cell counts were conducted from scanning electron microscopy (SEM) images. Results: Differences in surface roughness across all instruments tested for zirconia disks were negligible, while both titanium disks and titaniumzirconium disks showed large differences in surface roughness across the spectrum of instruments tested. The rotary titanium brush and the titanium curette yielded the greatest overall mean surface roughness, while the plastic curette yielded the lowest mean surface roughness. The greatest mean cell counts for each disk type were as follows: titanium disks with plastic curettes, titanium-zirconium disks with titanium curettes, and zirconia disks with the diode microlaser. Conclusion: Repeated instrumentation did not result in cumulative changes in surface roughness of implant materials made of titanium, titanium-zirconium, or zirconia. Instrumentation with plastic implant curettes on titanium and zirconia surfaces appeared to be more favorable than titanium implant curettes in terms of gingival fibroblast attachment on these surfaces.

Lysophosphatidic acid (LPA) is a phospholipid mediator that plays multiple cellular functions by acting through G protein-coupled LPA receptors. LPAs are known to be key mediators in inflammation, and several lines of evidence suggest a role for LPAs in inflammatory periodontal diseases. A simple and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method has been developed and validated to quantify LPA species (LPA 18:0, LPA 16:0, LPA 18:1 and LPA 20:4) in human saliva and gingival crevicular fluid (GCF). LPA 17:0 was used as an internal standard and the LPA species were extracted from saliva by liquid-liquid extraction using butanol. Chromatography was performed using a Macherey-Nagel NUCLEODUR® C8 Gravity Column (125 mm × 2.0 mm ID) with a mixture of methanol/water: 75/25 (v/v) containing 0.5% formic acid and 5 mM ammonium formate (mobile phase A) and methanol/water: 99/0.5 (v/v) containing 0.5% formic acid and 5mM ammonium formate (mobile phase B) at a flow rate of 0.5 mL/min. LPAs were detected by a linear ion trap-triple quadrupole mass spectrometer with a total run time of 8.5 min. The limit of quantification (LOQ) in saliva was 1 ng/mL for all LPA species and the method was validated over the range of 1-200 ng/mL. The method was validated in GCF over the ranges of 10-500 ng/mL for LPA 18:0 and LPA 16:0, and 5-500 ng/mL for LPA 18:1 and LPA 20:4. This sensitive LC-MS/MS assay was successfully applied to obtain quantitative data of individual LPA levels from control subjects and patients with various periodontal diseases. All four LPA species were consistently elevated in samples obtained from periodontal diseases, which supports a role of LPAs in the pathogenesis of periodontal diseases.

Migration of fibroblasts plays an essential role in tissue repair after injury. Sphingosine 1-phosphate (S1P) is a multifunctional mediator released by many cells that can be released in inflammation and after injury. This study evaluated the effect of S1P on fibroblast chemotaxis toward fibronectin. S1P alone did not affect fibroblast migration, but S1P enhanced fibronectin-directed chemotaxis in a concentration-dependent manner. The effect of S1P was not mimicked by dihydro (dh) S1P or the S1P(1) receptor agonist SEW2871. S1P augmentation of fibroblast chemotaxis, however, was completely blocked by JTE-013, an S1P(2) antagonist, but not by suramin, an S1P(3) antagonist. Suppression of the S1P(2) receptor by small interfering (si)RNA also completely blocked S1P augmentation of fibroblast chemotaxis to fibronectin. S1P stimulated Rho activation and focal adhesion kinase (FAK) phosphorylation, and these were also significantly inhibited by the S1P(2) receptor antagonist (JTE-013) or by S1P(2) siRNA. Further, the potentiation of S1P signaling was blocked by the Rho-kinase inhibitor Y-27632 in a concentration-dependent manner. Inhibition of FAK with siRNA reduced basal chemotaxis toward fibronectin slightly but significantly, and almost completely blocked S1P augmented chemotaxis. These results suggest that S1P-augmented fibroblast chemotaxis toward fibronectin depends on the S1P(2) receptor and requires Rho and Rho-kinase, and FAK phosphorylation. By augmenting fibroblast recruitment, S1P has the potential to modulate tissue repair after injury. The pathways by which S1P mediates this effect, therefore, represent a potential therapeutic target to affect tissue repair and remodeling.

Enhanced proliferation of airway smooth muscle is thought to contribute to the pathogenesis of asthma and other obstructive airway diseases. Lysophosphatidic acid (LPA) is a simple bioactive lipid mediator that stimulates mitogenesis in fibroblasts and some other cell types. The effects of LPA on mitogenesis of cultured human airway smooth muscle cells were determined by measuring [3H]thymidine incorporation into cellular DNA. LPA induced a concentration-dependent stimulation of [3H]thymidine incorporation of a similar magnitude to that induced by serum, with the effects of 50 microM LPA being similar to those of 5% serum. Stimulation by LPA and by serum was almost completely eliminated in cells exposed to pertussis toxin, indicating involvement of a pertussis toxin-sensitive G protein in mitogenic signaling by these agents. Epidermal growth factor (EGF) induced stimulation of a similar magnitude as that with LPA, but the stimulation by EGF was insensitive to pertussis toxin. LPA and EGF, when added together, exhibited a markedly synergistic stimulation of [3H]thymidine incorporation that was typically 10-fold greater than the stimulation with either agent alone. LPA and EGF also stimulated mitogenesis assessed by cell growth, and again LPA and EGF together exhibited synergism. These results suggest the possibility that stimulation of airway smooth muscle cell proliferation by LPA, either alone or by enhancing effects of other growth factors, could play a role in normal airway remodeling or in the pathological proliferation of smooth muscle in various airway diseases.

Cytokines are a heterogenous group of polypeptide mediators that have been associated with activation of numerous functions, including the immune system and inflammatory responses. The cytokine families include, but are not limited to, interleukins (IL-I alpha, IL-I beta, ILIra and IL-2-IL-15), chemokines (IL-8/ NAP-I, NAP-2, MIP-I alpha and beta, MCAF/MCP-1, MGSA and RANTES), tumor necrosis factors (TNF-alpha and TNF-beta), interferons (INF-alpha, beta and gamma), colony stimulating factors (G-CSF, M-CSF, GM-CSF, IL-3 and some of the other ILs), growth factors (EGF, FGF, PDGF, TGF alpha, TGF beta and ECGF), neuropoietins (LIF, CNTF, OM and IL-6), and neurotrophins (BDNF, NGF, NT-3-NT-6 and GDNF). The neurotrophins represent a family of survival and differentiation factors that exert profound effects in the central and peripheral nervous system (PNS). The neurotrophins are currently under investigation as therapeutic agents for the treatment of neurodegenerative disorders and nerve injury either individually or in combination with other trophic factors such as ciliary neurotrophic factor (CNTF) or fibroblast growth factor (FGF). Responsiveness of neurons to a given neurotrophin is governed by the expression of two classes of cell surface receptor. For nerve growth factor (NGF), these are p75NTR (p75) and p140trk (referred to as trk or trkA), which binds both BDNF and neurotrophin (NT)-4/5, and trkC receptor, which binds only NT-3. After binding ligand, the neurotrophin-receptor complex is internalized and retrogradely transported in the axon to the soma. Both receptors undergo ligand-induced dimerization, which activates multiple signal transduction pathways. These include the ras-dependent pathway utilized by trk to mediate neurotrophin effects such as survival and differentiation. Indeed, cellular diversity in the nervous system evolves from the concerted processes of cell proliferation, differentiation, migration, survival, and synapse formation. Neural adhesion and extracellular matrix molecules have been shown to play crucial roles in axonal migration, guidance, and growth cone targeting. Proinflammatory cytokines, released by activated macrophages and monocytes during infection, can act on neural targets that control thermogenesis, behavior, and mood. In addition to induction of fever, cytokines induce other biological functions associated with the acute phase response, including hypophagia and sleep. Cytokine production has been detected within the central nervous system as a result of brain injury, following stab wound to the brain, during viral and bacterial infections (AIDS and meningitis), and in neurodegenerative processes (multiple sclerosis and Alzheimer's disease). Novel cytokine therapies, such as anticytokine antibodies or specific receptor antagonists acting on the cytokine network may provide an optimistic feature for treatment of multiple sclerosis and other diseases in which cytokines have been implicated.

Metallothionein (MT) isoforms I and II were first identified and characterized in our laboratories in several regions of brain, in hippocampal neurons in primary culture, and in retinoblastoma and neuroblastoma cell lines. In this study, by having employed the MT-I cDNA as a probe, we sought to gain additional insight about the function of MT by discerning the regional distribution of its mRNA. Northern blot analyses of brain mRNA revealed that the administration of zinc enhanced dramatically MT-I mRNA (570 bp). The in situ hybridization study revealed that MT-I mRNA was located in several areas of brain, with the highest concentrations found in the cerebellum, hippocampus, and ventricles. The results of these studies are interpreted to suggest that zinc enhances the synthesis of MT mRNA and MT in turn may participate in zinc associated functions in neurons.

Diabetes mellitus consists of a group of disorders, which are characterized by a lack of insulin production or insulin resistance. There can be various oral manifestations of diabetes, such as xerostomia and an increased incidence of dental caries. Recently, it has been suggested that periodontitis be added as the sixth complication of diabetes mellitus. It has been shown that uncontrolled or poorly controlled diabetics have a greater incidence of severe periodontal disease compared with those patients who are well controlled or have no diabetes mellitus. This has been found for both type 1 and type 2 diabetics. In addition, the diabetic patient may be predisposed to periodontal disease based on the production of advanced glycation end products, which bind to receptors on specific cells such as the monocyte. The success of periodontal treatment appears to be dependent on the control exhibited by the diabetic patient. The well-controlled diabetic will respond well to periodontal treatment, while the uncontrolled or poorly controlled will often not respond well or be stable in the long-term. Because of the large number of diabetics in the US population, dental therapists should be aware of the interactions of the patient's diabetic status, the proposed treatment, and the possible treatment outcomes as well as complications.

3H-antagonists are known to bind to the alpha-2A adrenergic receptor with higher affinity in glycylglycine buffer than in Tris buffer. The purpose of this study was to examine the effect of buffers on the binding of antagonists to all four subtypes of the alpha-2 adrenergic receptor. Our approach was to examine the effects of glycylglycine, Tris, sodium phosphate (NaPO4) and potassium phosphate buffers on the binding of [3H]rauwolscine, [3H]RX821002, prazosin and oxymetazoline. We found that the affinities for the different subtypes varied with the buffer and the ligands used. Although the Bmax values varied somewhat with the buffers, they were similar for both radioligands for a specific subtype. The highest affinities and Bmax values for both radioligands were generally obtained with NaPO4 buffer. The affinities of antagonists in Tris buffer were always significantly lower than in either NaPO4 or glycylglycine buffer, and the affinities decreased as the concentration of Tris increased. In contrast, the affinity of norepinephrine for the alpha-2B subtype was higher in Tris than in NaPO4 buffer. The buffer effects did not appear to be dependent on the cell membrane composition. There appeared to be some species differences in the effects of buffers on the alpha-2C subtype. These results indicate that buffers affect the binding of antagonists to alpha-2 adrenergic receptors, that not all subtypes are altered in the same manner and that buffers alter the binding of different antagonists differently. It is generally recommended that NaPO4 buffer be used, and that Tris be avoided, when measuring the binding of antagonists to the alpha-2 adrenergic receptor.

Many, but not all, zinc-containing neurons in the brain are a subclass of the glutamatergic neurons, and they are found predominantly in the telencephalon. These neurons store zinc in their presynaptic terminals and release it by a calcium-dependent mechanism. These "vesicular" pools of zinc are viewed as endogenous modulators of ligand- and voltage-gated ion channels. Metallothioneins (MTs) are low molecular weight zinc-binding proteins consisting of 25-30% cysteine, with no aromatic amino acids or disulfide bonds. The areas of the brain containing high contents of zinc such as the retina, the pineal gland, and the hippocampus synthesize unique isoforms of MT on a continuous basis. The four MT isoforms are thought to provide the neurons and glial elements with mechanisms to distribute, donate, and sequester zinc at presynaptic terminals; or buffer the excess zinc at synaptic junctions. In this cause, glutathione disulfide may participate in releasing zinc from MT. A similar nucleotide and amino acid sequence has made it difficult to obtain cDNA probes and antibodies capable of distinguishing indisputably among MT isoforms. MT-I and MT-II isoforms are found in the brain and in the peripheral tissues; MT-III isoform, possessing an additional seven amino acids, is expressed mostly in the brain and to a very minute extent in the intestine and pancreas; whereas MT-IV isoform is found in tissues containing stratified squamous epithelial cells. Since MTs are expressed in neurons that sequester zinc in their synaptic vesicles, the regulation of the expression of MT isoforms is extremely important in terms of maintaining the steady-state level of zinc and controlling redox potentials. The concentration of zinc has been shown to be altered in an extensive number of disorders of the central nervous system, including alcoholism. Alzheimer-type dementia, amyotrophic lateral sclerosis, Down's syndrome, epilepsy, Friedreich's ataxia, Guillaine-Barre syndrome, hepatic encephalopathy, multiple sclerosis, Parkinson's disease, Pick's disease, retinitis pigmentosa, retinal dystrophy, schizophrenia, and Wernicke-Korsakoff syndrome. The status of MT isoforms and other low molecular weight zinc-binding proteins in these conditions, diseases, disorders, or syndromes is being delineated at this time. Since several of these disorders, such as amyotrophic lateral sclerosis, are associated with oxidative stress, and since MT is able to prevent the formation of free radicals, it is believed that cytokine-induced induction of MT provides a long-lasting protection to avert oxidative damage.

The alpha 2-adrenergic receptors have been divided into four pharmacological subtypes, alpha 2A, alpha 2B, alpha 2C, and alpha 2D. The OK cell line, a cell line derived from an opossum kidney, expresses the alpha 2C-adrenergic receptor and is the prototypical cell line for the alpha 2C receptor subtype. The cloned human alpha 2C-C4 and rat RG10 receptors have been shown to express alpha 2C pharmacology. Here we report the cloning and expression of the OK alpha 2C-adrenergic receptor, OKc2. The receptor has 64% deduced amino acid identity and 21% similarity to the alpha 2-C4 receptor, giving an overall similarity of 85%. The clone, expressed in Chinese hamster ovary cells, has a pharmacology that correlates very well (r = 0.97) with that of the native OK cell alpha 2C-adrenergic receptor, and it is negatively coupled to adenylyl cyclase.

Serotonin (5-hydroxytryptamine or 5-HT) is an important biogenic amine that functions as both a neurotransmitter and a hormone in the central nervous system (CNS) and the periphery. We report here the isolation of a cDNA from the OK cell that encodes a serotonin receptor (OKc1). When expressed in cultured cells, it displayed the pharmacological profile and negative coupling with adenylyl cyclase characteristic of a 5-HT1B receptor subtype. Similar to the cloned rodent 5-HT1B receptors, it had high affinity for the beta-adrenergic ligand [125I]iodocyanopindolol, because of the presence of an asparagine instead of a threonine residue in the seventh transmembrane region. The ligands used displayed the following rank order of potencies: cyanopindololRU24969methiothepinserotoninsumatriptanmethysergide8-OH-DPATisoproterenol. This profile correlates well (r = 0.97) with the native OK cell 5-HT1B receptor. When OKc1 is compared to the rat, mouse, and human 5-HT1B receptors, it has an amino acid sequence identity of 82%, but it is only 54% identical to the human 5-HT1D receptor.

cDNAs corresponding to RNA from the autonomous parvovirus minute virus of mice were cloned into constitutive and inducible expression vectors. These clones generate viral NS2, VP1, and VP2 proteins individually. Initial examination of these clones by transient expression analysis and analysis of stably transformed murine cell lines inducibly expressing these constructs indicated that they will be useful tools for characterizing the function of individual minute virus of mice gene products.