The juxta-oral organ of Chievitz (organum yuxtaorale) updated: Embryology, anatomy, function and pathology.

BACKGROUND: The Chievitz's organ or juxta-oral organ is a mysterious bilateral structure, phylogenetically preserved, which develops from the mouth epithelium as an invagination that loses connection to it in the prenatal period. It is located laterally to the walls of the oral cavity in an imprecise anatomical location and receives abundant innervation from the buccal nerve. Structurally it consists of non-keratinizing squamous-like neuroepithelial cells surrounded by two layers of connective tissue with nerve fibers and different morphotypes of sensory corpuscles. Its function is completely unknown although based on its rich innervation it is assumed that works as a mechanoreceptor. METHODS: We have performed immunohistochemistry for axonal and Schwann cells, and the putative mechanoproteins ASIC2, TRPV4 and Piezo2 in sections of fetal juxta-oral organ. RESULTS: Intraparenchymatous nerve fibers and sensory corpuscles were observed as well as immunoreactivity for Piezo2 in both nerve fibers and epithelial parenchymatous cells. CONCLUSIONS: We add indirect evidence that the juxtaoral organ is a mechanoreceptor because in addition to its dense innervation, the epithelial cells and sensory nerve fibers display immunoreactivity for the mechanogated ion channel Piezo2. Based on current knowledge, the functional and clinical importance of the juxta-oral organ should be further investigated.

Medication-related osteonecrosis of the jaw. Implant presence-triggered osteonecrosis: Case series and literature review.

PURPOSE: The aim of this study was to review the characteristics of 'implant presence-triggered osteonecrosis' (IPTO) in the literature and identify possible differences between IPTOs and 'implant surgery-triggered osteonecrosis' (ISTO). MATERIALS AND METHODS: Reviews using PubMed and the Cochrane Database of Systematic Reviews were performed from 2009-2018; the focus was on medication-related osteonecrosis of the jaw (MRONJ) and dental implants. In addition, the hospital records of all patients presented in our department with IPTO were retrospectively reviewed. In both studies, the following data were collected: the number of patients with ISTO or IPTO, age, gender, location, stage of MRONJ, number of implants involved in MRONJ, the elapsed time between the placement of the implants and the development of MRONJ, applied treatment and the presence of mandibular fractures and progress. RESULTS: The literature review provided 111 articles. Nine of the articles were selected for bibliographic review. The number of osteonecrosis cases was significantly higher in the IPTO group (74 cases) compared with the ISTO group (27 cases). The duration of the anti-resorptive treatment (oral and intravenous) was also longer in the IPTO group. In our centre, seven patients with IPTO were chosen; however, no patients with ISTO were selected. The significant differences between the patients in our series and the information collected in the literature for the IPTO group were the time of ingestion of alendronate, the elapsed time from the placement of the implants to the development of the MRONJ and the number of implants linked to the development of a complication. CONCLUSIONS: The use of antiresorptives causes osteonecrosis in patients with implants that are subjected to functional loading, and this occurs at a higher frequency than what is observed after implant placement surgery.

Pacinian Corpuscles in Human Lymph Nodes.

The occurrence of Pacinian corpuscles associated to lymph nodes is an anatomical rarity and very scarce information exists in this regard. Here we examined immunohistochemically four Pacinian corpuscles found in the close vicinity of the hiliar blood vessels of lymph nodes (2 cervical, 1 axillary, and 1 inguinal) during routine surgical pathology. Pacinian corpuscles were normally arranged and displayed a pattern of protein distribution as follows: the axon was positive for neurofilament proteins and neuron specific enolase, the inner core cells showed intense S100 protein and vimentin immunostaining while they were negative for glial fibrillary acidic protein, type IV collagen and glucose transporter 1; vimentin, type IV collagen, and glucose transporter 1 were also observed also in the outer-core and the capsule. These results are in agreement with those reported for cutaneous Pacinian corpuscles, demonstrating that the immunohistochemical profile of these corpuscles is independent of its anatomical localization. The possible functional significance of Pacinian corpuscles in lymph nodes is discussed. Anat Rec, 300:2233-2238, 2017. © 2017 Wiley Periodicals, Inc.

Innervation of the Human Cavum Conchae and Auditory Canal: Anatomical Basis for Transcutaneous Auricular Nerve Stimulation.

The innocuous transcutaneous stimulation of nerves supplying the outer ear has been demonstrated to be as effective as the invasive direct stimulation of the vagus nerve for the treatment of some neurological and nonneurological disturbances. Thus, the precise knowledge of external ear innervation is of maximal interest for the design of transcutaneous auricular nerve stimulation devices. We analyzed eleven outer ears, and the innervation was assessed by Masson's trichrome staining, immunohistochemistry, or immunofluorescence (neurofilaments, S100 protein, and myelin-basic protein). In both the cavum conchae and the auditory canal, nerve profiles were identified between the cartilage and the skin and out of the cartilage. The density of nerves and of myelinated nerve fibers was higher out of the cartilage and in the auditory canal with respect to the cavum conchae. Moreover, the nerves were more numerous in the superior and posterior-inferior than in the anterior-inferior segments of the auditory canal. The present study established a precise nerve map of the human cavum conchae and the cartilaginous segment of the auditory canal demonstrating regional differences in the pattern of innervation of the human outer ear. These results may provide additional neuroanatomical basis for the accurate design of auricular transcutaneous nerve stimulation devices.

Endoneurial-CD34 positive cells define an intermediate layer in human digital Pacinian corpuscles.

The endoneurial and/or perineurial origin of the outer core; i.e. the concentric and continuous lamellae located outside the complex formed by the axon and the Schwann-related cells, in human Pacinian corpuscles is still debated. Here we used immunohistochemistry coupled with a battery of antibodies to investigate the expression of perineurial (Glucose transporter 1 and epithelial membrane antigen) or endoneurial (CD34 antigen) markers in human digital Pacinian corpuscles. CD34 immunoreactivity was restricted to one layer immediately outside the inner core, whereas the proper outer core displayed antigens typical of the perineurial cells. These results demonstrate an intermediate endoneurial layer that divides the Pacinian corpuscles into two distinct compartments: the avascular inner neural compartment (formed by the axon and the Schwann-related cells that form the inner core), and the outer non-neural compartment (formed by the outer core). The functional relevance of these findings, if any, remains to be clarified.

Acid-sensing ion channel immunoreactivities in the cephalic neuromasts of adult zebrafish.

The neuromasts are the morphofunctional unit of the lateral line system serving as mechanosensors for water flow and movement. The mechanisms underlying the detection of the mechanical stimuli in the vertebrate mechanosensory cells remain poorly understood at the molecular level, and no information is available on neuromasts. Mechanotransduction is the conversion of a mechanical stimulus into an electrical signal via activation of ion channels. The acid-sensing ion channels (ASICs) are presumably involved in mechanosensation, and therefore are expected to be expressed in the mechanoreceptors. Here we used immunohistochemistry to investigate the occurrence and distribution of ASICs in the cephalic neuromasts of the adult zebrafish. Specific immunoreactivity for ASIC1 and ASIC4 was detected in the hair cells while ASIC2 was restricted to the nerves supplying neuromasts. Moreover, supporting and mantle cells; i.e., the non-sensory cells of the neuromasts, also displayed ASIC4. For the first time, these results demonstrate the presence of the putative mechanoproteins ASIC1, ASIC2 and ASIC4 in neuromasts, suggesting a role for these ion channels in mechanosensation.

Mechanosensory neurons, cutaneous mechanoreceptors, and putative mechanoproteins.

The mammalian skin has developed sensory structures (mechanoreceptors) that are responsible for different modalities of mechanosensitivity like touch, vibration, and pressure sensation. These specialized sensory organs are anatomically and functionally connected to a special subset of sensory neurons called mechanosensory neurons, which electrophysiologically correspond with Aß fibers. Although mechanosensory neurons and cutaneous mechanoreceptors are rather well known, the biology of the sense of touch still remains poorly understood. Basically, the process of mechanosensitivity requires the conversion of a mechanical stimulus into an electrical signal through the activation of ion channels that gate in response to mechanical stimuli. These ion channels belong primarily to the family of the degenerin/epithelium sodium channels, especially the subfamily acid-sensing ion channels, and to the family of transient receptor potential channels. This review compiles the current knowledge on the occurrence of putative mechanoproteins in mechanosensory neurons and mechanoreceptors, as well as the involvement of these proteins on the biology of touch. Furthermore, we include a section about what the knock-out mice for mechanoproteins are teaching us. Finally, the possibilities for mechanotransduction in mechanoreceptors, and the common involvement of the ion channels, extracellular membrane, and cytoskeleton, are revisited.

[Donation after cardiac death: cardiac arrest during donor maintenance after brain death]. / Donación tras la muerte cardíaca. Parada cardíaca en el mantenimiento del donante en muerte encefálica.

Brain death implies the complete cessation of activity in both cerebral hemispheres and in the brainstem; this leads to severe physiopathological disorders that make donor maintenance complex and involve the concomitant risk of rapid organ deterioration. The heart is one of the target organs in this process of multiple organ failure. Myocardial stunning occurs due to a "catecholamine storm" and subsequent release of many proinflammatory mediators, free oxygen radicals, and electrolyte imbalance secondary to insipid diabetes and hypothermia. Cardiac arrest during the maintenance of a donor after brain death is relatively frequent. The shortage of organs for transplantation has led to the broadening of the criteria for organ donation to include donation after cardiac death or non heart beating donation, among others.

TrkB is necessary for the normal development of the lung.

Normal development of the lung requires coordinated activation of cascades of signaling pathways initiated by growth factors signaling through their receptors. TrkB and its ligands, brain-derived neurotrophic factor (BDNF) and neurotrophin-4, belong to the neurotrophin family of growth factors, which are expressed in a large variety of non-neuronal tissues including the lung. Aberrant neurotrophin signaling underlies the pathogenesis of several lung-related pathologies, including asthma and lung cancer, however, little is known about the role of neurotrophins in the embryonic development of the lung. To fill this gap in knowledge, we analyzed the pattern of TrkB expression in the murine lung and we observed that TrkB is expressed in alveolar macrophages, type II pneumocytes, neuroepithelial bodies and nerves. Analysis of the structure of lung from mice deficient in TrkB revealed that absence of TrkB signaling results in thinner bronchial epithelium and apparent larger air space, and, more importantly, lack of neuroepithelial bodies, an important reduction in the density of nerve fibres in the bronchial smooth muscle, submucous plexus in bronchioles, and pulmonary artery walls. These findings suggest TrkB is essential for the normal development of the lung and the nervous system in the lung.

Medicina de cuidados intensivos / Intensive care medicine

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Muerte encefálica. Evolución histórica y situación actual / Brain death. Historical overview and current situation

En este artículo se presenta una revisión histórica del concepto de muerte de un ser vivo y de la importancia de las Unidades de Cuidados Intensivos, sobre todo del desarrollo de las técnicas de soporte vital, en la aparición del concepto de muerte encefálica (también denominada muerte cerebral). Fue la inquietud médica por realizar un diagnóstico certero de la muerte en pacientes sometidos a ventilación mecánica lo que motivó el desarrollo de nuevas definiciones de muerte basadas en la pérdida definitiva de las funciones del sistema nervioso central. Se analizan los diferentes criterios de muerte encefálica que se han utilizado a través del tiempo y que soportan los tres conceptos de muerte encefálica que se manejan en la actualidad: muerte de todo el encéfalo, muerte del tronco cerebral y muerte de la neocorteza cerebral. De cada uno de ellos, se revisa el propio concepto de muerte, los criterios asociados a esa definición, las pruebas o procedimientos diagnósticos a utilizar, y los argumentos a favor y en contra de su aceptación generalizada. Se concluye que a la luz de los conocimientos actuales, el cese irreversible de las funciones encefálicas (sin entrar a definir la porción del encéfalo que debe perder irreversiblemente sus funciones) es el único concepto válido de muerte, ya que no existe ninguna posibilidad de soporte o suplencia de las funciones del sistema nervioso central. Por su aceptación generalizada y por ser el utilizado desde un punto de vista legal en la mayoría de los países de nuestro entorno, incluida España, hemos asumido el concepto de "muerte de todo el encéfalo", dado que, además, ha proporcionado un abordaje práctico y socialmente aceptable de la definición de muerte (AU)

[Serum and pulmonary angiotensin converting enzyme as a marker of acute lung injury in an experimental model of adult respiratory distress syndrome]. / La enzima de conversión de la angiotensina (sérica y pulmonar) en un modelo experimental de distrés respiratorio del adulto, como marcador de lesión aguda pulmonar.

OBJECTIVE: To know if the determination of the angiotensin converting enzyme in serum (SACE) and lung (LACE) may be useful as a marker of acute lung injury (ALI) in the adult respiratory distress syndrome (ARDS). METHOD: By reproducing in a experimental model of ALI with oleic acid in dogs which simulate the early stage of ARDS, we have correlated the pathologic and analytical changes observed with the results of the determinations of SACE and LACE. RESULTS: We have found sequential pulmonary lesions (congestion, edema, hemorrhage polynuclear infiltration and thrombosis) and biological alteration (hypoxemia, pulmonary hypertension, early leukopenia and final leukocytosis, thrombopenia and hypofibrinogenemia) that reproduce the typical changes of ARDS, together with the decrease of SACE--slow and progressive--and LACE--abrupt in the onset and maintained during the experiment--. CONCLUSIONS: The LACE is a good marker of the beginning of the lesion because its decrease coincides with the first pathological changes (congestion) and with the hypoxemia, pulmonary hypertension and leukopenia, maintained without changes, during the whole experiment. On the other hand, the SACE corresponds as an inespecifical reactant, marker of acute inflammation and loss of pulmonary endothelium, because its progressive decrease evolutioned with the pathological lesions and the analytical changes. In conclusion, the sequential determination of SACE has a prognostic and evolutive value in comparison with the LACE, which has a diagnostic value from the beginning of the experiment of ALI and maintained throughout.