Effect of selected metals on bone tissue of the masticatory apparatus / Efectos de metales en el tejido óseo del aparato masticatorio

The masticatory apparatus is a functional unit of the human body, which is mainly responsible for speech, chewing, and swallowing. It is built of bones, joints, ligaments, teeth, and muscles. In addition, the oral cavity and its hard tissues are the first ones to be exposed to exogenous factors during feeding and breathing. The aim of the work was to review the literature of recent years on the toxicology of metals and their possible negative and sometimes positive effects on the metabolism of bones of the masticatory apparatus. In summary, metals commonly found in the environment affect the bones of the masticatory apparatus to varying degrees. Attention should be paid to the sources of individual metals in the environment and to prevent their excessive, unwanted effects on the bones of the masticatory apparatus. (AU)

El aparato masticatorio constituye una unidad funcional del cuerpo humano especializada en la regulación y coordinación de los procesos del habla, la masticación y la deglución. Está constituida por huesos, ligamentos, articulaciones, músculos y dientes. El tejido óseo de la cavidad bucal es el primero en estar expuesto a factores exógenos durante la alimentación y la respiración. El objetivo del presente trabajo es realizar una revisión de lo reportado en la literatura en los últimos años, con respecto a los efectos beneficiosos o nocivos de los metales pesados sobre el metabolismo de los huesos del aparato masticatorio. En resumen, se evidencia que los metales presentes en el medioambiente afectan a estos huesos en diferentes grados. Se debe prestar especial atención a identificar las fuentes de donde provienen estos metales, para prevenir los efectos no deseados sobre el tejido óseo masticatorio generados por una excesiva exposición a ellos. (AU)

Molecular Changes Involving MEK3-p38 MAPK Activation in Chronic Masticatory Myalgia.

The exact mechanism underlying chronic masticatory myalgia (CMM), a conspicuous symptom in temporomandibular disorders, remains unclear. This investigation compared gene expression profiles between CMM patients and healthy subjects. Peripheral blood leukocytes were collected in 8 cases and 8 controls and subjected to whole genome microarray analyses. Data were analyzed with Gene Ontology and interactive pathways analyses. According to Gene Ontology analysis, categories such as ion transport, response to stimuli, and metabolic process were upregulated. The pathway analysis suggested overexpression of the mitogen-activated protein kinase (MAPK) pathway in CMM patients and to a higher degree in a pathway network. Overexpression of representative members of the MAPK pathway-including MAPK kinase 3 (MEK3), calcium voltage-gated channel auxiliary subunit gamma 2 (CACNG2), and growth arrest and DNA damage-inducible gamma (GADD45G)-was validated with real-time polymerase chain reaction. The upregulation of MEK3 was negatively correlated with the age of the CMM group. In the next step, the authors focused on MEK3, the gene that exhibited the greatest degree of differential expression, and its downstream target protein p38 MAPK. The results revealed upregulation of MEK3, as well as phosphorylated MEK3 and phosphorylated p38 MAPK, in CMM patients. These results provide a "fingerprint" for mechanistic studies of CMM in the future and highlight the importance of MEK3-p38 MAPK activation in CMM.

Involvement of NMDA receptors in the ventrolateral striatum of rats in apomorphine-induced jaw movements.

The role of NMDA receptors in the ventrolateral striatum to modulate dopamine receptor-mediated jaw movements was investigated in freely moving rats, using a magnetic sensor system combined with intracerebral microinjection of drugs. Apomorphine (1mg/kg i.v.) induced repetitive jaw movements that were reduced, in a dose-dependent manner, by bilateral microinjections of the NMDA receptor agonist NMDA (0.1 and 1mug/0.2mul bilaterally) into the ventrolateral striatum. Apomorphine-induced repetitive jaw movements were also reduced, in a dose-dependent manner, by bilateral microinjections of the NMDA receptor antagonists d-APV (0.01 and 0.1mug) or MK-801 (0.5 and 5mug). The inhibitory effect of NMDA (1mug) was reduced by co-administration of MK-801 (0.5mug). Microinjections of drugs into the ventrolateral striatum in the absence of apomorphine did not affect jaw movements. These results suggest that NMDA receptors in the ventrolateral striatum play an important modulatory role in the expression of dopamine receptor-mediated jaw movements. However, similar effects of NMDA and NMDA antagonists echo previous paradoxical findings and indicate that interactions between dopamine and NMDA receptors are complex and multifaceted. Cellular mechanism(s) may involve differential effects of NMDA agonism and antagonism on dopamine D1-like vs D2-like receptors and, possibly, on related GABAergic processes.

Dynorphin-A immunoreactive terminals on the neuronal somata of rat mesencephalic trigeminal nucleus.

Dynorphin-A-like immunoreactivity was investigated in the rat mesencephalic trigeminal nucleus (Mes 5) at the light and electron microscopic levels. Dynorphin-A immunoreactive fibers and puncta, likely representing nerve terminals, were observed throughout rostrocaudal extension of the Mes 5 at the light microscopic level. Within the rostrocaudal extension, more abundant fibers and puncta were localized in the midbrain-pontine junction and pontine areas than in the midbrain area. At the electron microscopic level, dynorphin-A immunoreactive synapses were observed on the somata of Mes 5. Dynorphin-A-like immunoreactivity tended to be restricted to dense-cored vesicles in the synapses. These results suggest that dynorphin-A-containing fiber systems affect mastication through the Mes 5.

Early Hedgehog signaling from neural to oral epithelium organizes anterior craniofacial development.

Hedgehog (Hh) signaling plays multiple roles in the development of the anterior craniofacial skeleton. We show that the earliest function of Hh is indirect, regulating development of the stomodeum, or oral ectoderm. A subset of post-migratory neural crest cells, that gives rise to the cartilages of the anterior neurocranium and the pterygoid process of the palatoquadrate in the upper jaw, condenses upon the upper or roof layer of the stomodeal ectoderm in the first pharyngeal arch. We observe that in mutants for the Hh co-receptor smoothened (smo) the condensation of this specific subset of crest cells fails, and expression of several genes is lost in the stomodeal ectoderm. Genetic mosaic analyses with smo mutants show that for the crest cells to condense the crucial target tissue receiving the Hh signal is the stomodeum, not the crest. Blocking signaling with cyclopamine reveals that the crucial stage, for both crest condensation and stomodeal marker expression, is at the end of gastrulation--some eight to ten hours before crest cells migrate to associate with the stomodeum. Two Hh genes, shh and twhh, are expressed in midline tissue at this stage, and we show using mosaics that for condensation and skeletogenesis only the ventral brain primordium, and not the prechordal plate, is an important Hh source. Thus, we propose that Hh signaling from the brain primordium is required for proper specification of the stomodeum and the stomodeum, in turn, promotes condensation of a subset of neural crest cells that will form the anterior neurocranial and upper jaw cartilage.

Importância do exame bucal na Clínica Médica / Importance of buccal exam in Medical Clinic

Com o objetivo de conscientizar o profissional generalista para a importância da realização do exame bucal, os autores apresentam revisão da literatura sobre o padrão clínico normal da cavidade bucal, padronização do exame bucal, lesões elementares, manifestações e apresentações das doenças na boca.