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Retrograde fluorescent labeling of dental primary afferent neurons (DPANs) has been described in rats through crystalline fluorescent DiI, while in the mouse, this technique was achieved with only Fluoro-Gold, a neurotoxic fluorescent dye with membrane penetration characteristics superior to the carbocyanine dyes. We reevaluated this technique in the rat with the aim to transfer it to the mouse because comprehensive physiologic studies require access to the mouse as a model organism. Using conventional immunohistochemistry, we assessed in rats and mice the speed of axonal dye transport from the application site to the trigeminal ganglion, the numbers of stained DPANs, and the fluorescence intensity via 1) conventional crystalline DiI and 2) a novel DiI formulation with improved penetration properties and staining efficiency. A 3-dimensional reconstruction of an entire trigeminal ganglion with 2-photon laser scanning fluorescence microscopy permitted visualization of DPANs in all 3 divisions of the trigeminal nerve. We quantified DPANs in mice expressing the farnesylated enhanced green fluorescent protein (EGFPf) from the transient receptor potential cation channel subfamily M member 8 (TRPM8EGFPf/+) locus in the 3 branches. We also evaluated the viability of the labeled DPANs in dissociated trigeminal ganglion cultures using calcium microfluorometry, and we assessed the sensitivity to capsaicin, an agonist of the TRPV1 receptor. Reproducible DiI labeling of DPANs in the mouse is an important tool 1) to investigate the molecular and functional specialization of DPANs within the trigeminal nociceptive system and 2) to recognize exclusive molecular characteristics that differentiate nociception in the trigeminal system from that in the somatic system. A versatile tool to enhance our understanding of the molecular composition and characteristics of DPANs will be essential for the development of mechanism-based therapeutic approaches for dentine hypersensitivity and inflammatory tooth pain. [ABSTRACT FROM AUTHOR]

Background Mucoepidermoid carcinoma (MEC) of the skin is an uncommon neoplasm with a remarkable resemblance to MEC of the salivary glands. The latter has been shown to harbour an oncogenic translocation resulting in a fusion gene consisting of exon 1 of CRTC1/MECT1/TORC1 at 19p and exons 2–5 of MAML2 at 11q. Objectives While t(11;19) and rearrangements of the involved loci have been demonstrated in MEC of the salivary gland and other sites, it remains to be determined if morphological similarities in cutaneous MEC are reflected at the molecular level. Methods Cases of cutaneous MEC were defined by three histopathological features: (i) cystic dermal nodule with (ii) overlying intact epidermis and (iii) presence of three cell types (squamoid, intermediate, mucinous), and characterized by reverse transcription-polymerase chain reaction (RT-PCR), interphase fluorescent in situ hybridization (FISH) and immunohistochemistry. Results Eight primary cutaneous MECs were analysed. All informative cases showed CRTC1 rearrangements; none of the cases had MAML2 rearrangements or the presence of t(11;19) by RT-PCR. One case of primary MEC of the breast showed amplification of MAML2 in the absence of CRTC1 or t(11;19). Two MECs metastatic to the skin, histologically identical to primary cutaneous MEC, were included, one of which harboured the CRTC1– MAML2 fusion gene by RT-PCR, verified by interphase FISH and sequencing. Conclusions MEC of the skin harbours CRTC1 rearrangements, a molecular finding that reflects morphological similarities between glandular and cutaneous MEC. The absence of oncogenic t(11;19) or MAML2 aberrations in our series, which is the largest reported, may explain the innocuous clinical behaviour of this uncommon adnexal tumour. [ABSTRACT FROM AUTHOR]

Emerging evidence indicates a nociceptive role of vagal afferents. A distinct oesophageal innervation in the rat, with muscular and mucosal afferents travelling predominantly in the recurrent (RLN) and superior laryngeal nerve (SLN), respectively, enabled characterization of mucosal afferents with nociceptive properties, using novel isolated oesophagus–nerve preparations. SLN and RLN single-fibre recordings identified 55 and 14 units, respectively, with none conducting faster than 8.7 m s−1. Mucosal response characteristics in the SLN distinguished mechanosensors ( n= 13), mechanosensors with heat sensitivity (18) from those with cold sensitivity (19) and a mechanoinsensitive group (5). The mechanosensitive fibres, all slowly adapting, showed a unimodal distribution of mechanical thresholds (1.4–128 mN, peak ∼5.7 mN). No difference in response characteristics of C and Aδ fibres was encountered. Mucosal proton stimulation (pH 5.4 for 3 min), mimicking gastro-oesophageal reflux disease (GORD), revealed in 31% of units a desensitizing response that peaked around 20 s and faded within 60 s. Cold stimulation (15°C) was proportionally encoded but the response showed slow adaptation. In contrast, the noxious heat (48°C) response showed no obvious adaptation with discharge rates reflecting the temperature's time course. Polymodal (69%) mucosal units, > 30% proton sensitive, were found in each fibre category and were considered nociceptors; they are tentatively attributed to vagal nerve endings type I, IV and V, previously morphologically described. All receptive fields were mapped and the distribution indicates that the posterior upper oesophagus may serve as a ‘cutbank’, detecting noxious matters, ingested or regurgitated, and triggering nocifensive reflexes such as bronchoconstriction in GORD. [ABSTRACT FROM AUTHOR]

The presence of a small amount of macroscopic fat is not unusual in the hilar region of normal lymph nodes. However, abundant replacement of the lymph node with fat is highly unusual and may appear as metastatic lymph node disease in the course of fat-predominant liposarcomas or in the case of coeliac disease complicated by cavitating lymph node syndrome. In this case report, a patient with chronic lymphocytic leukaemia/small lymphocytic lymphoma who demonstrated an increasing abundance of macroscopic fat in the diseased lymph nodes is presented. To the best of our knowledge, the imaging findings of abundant fat in lymph nodes in the course of lymphoma have not been reported before. The presence of macroscopic fat may be seen in the presence of actively involved lymph nodes in the presence of chronic lymphocytic leukaemia. [ABSTRACT FROM AUTHOR]