Orofacial Tissues Research Articles

Acquired angioedema in non-Hodgkin’s lymphoma

This paper describes a middle-aged patient who developed repeated episodes of swelling of the orofacial tissues after dental treatment. On investigation, C1 inhibitor, C1q, C2, and C4 levels were all markedly reduced, and a diagnosis of acquired C1 inhibitor deficiency was made. The patient had been diagnosed with non-Hodgkin's lymphoma (NHL) 2 years previously and had undergone a successful course of chemotherapy. The development of her episodes of angioedema prompted thorough reinvestigation and a recurrence of NHL was identified. Therefore, acquired C1 inhibitor deficiency heralded a recurrence, although this had not been a manifestation when NHL was first diagnosed. The patient underwent a further course of chemotherapy and remains well, although C1 inhibitor, C1q, C2, and C4 levels remain reduced.

Expression of Ki-67 and p53 in cutaneous free flaps used to reconstruct soft tissue defects following resection of oral squamous cell carcinoma

Radial forearm free flaps are used routinely to reconstruct oro-facial tissues following resection of oral squamous cell carcinoma. Surprisingly, there is little information regarding their behaviour following engraftment. The present report is a clinico-pathological study of 10 patients who had incisional biopsies of cutaneous free flaps after the presence of a white patch or erythema raised clinical suspicion. Tissues were stained with haematoxylin and eosin, diastase-periodic acid-Schiff reagent and labelled immunohistochemically for Ki-67 and p53. Four of 10 specimens showed severe epithelial dysplasia within the graft, which was contiguous with dysplasia in the adjacent oral mucosa; the remaining grafts had features typical of candidosis (n=4) or hyperkeratosis (n=2). Grafts with dysplasia had a significantly higher Ki-67 labelling index than lesions in the 'non-dysplastic' group. There were no significant differences in the Ki-67 labelling index between areas of dysplasia in the graft and areas of dysplasia in the adjacent oral epithelium. p53 staining was present in all strata of the epithelium in the dysplastic grafts and adjacent dysplastic mucosa, but was absent or weakly expressed in the stratum basale of grafts showing reactive changes only. None of the dysplastic lesions progressed to carcinoma despite a mean follow-up period of 32 months; one patient developed a recurrent mucosal tumour at the resection margin. These observations indicate that cutaneous free flaps grafted to a site of field cancerisation can develop severe epithelial dysplasia with concomitant deregulation of proliferation and increased p53 expression. Such changes raise the possibility that these lesions have the potential for malignant transformation.

Stomatologie gériatrique

The practice of stomatology and maxillo-facial surgery in the elderly has become more frequent, in relation with lengthened life expectancy. The management of older patients induces frequent and constraining problems due to the repercussions of ageing on orofacial tissues; these repercussions consist of various intricate diseases that more or less directly interfere with the general disease. Besides, “normal senescence” may not or hardly be distinguished from a pathological state. The frailty of older patients, their uncertain participation, the constraints and risks related to their poly-medication constitute a wide range of problems in their therapeutic management. The risk of under- or over-consumption of drugs is also to be considered, particularly in cutaneous or oral cancerology. Lastly, it should be reminded that in most cases, age-related functional and aesthetic disorders are the main reason for seeking treatment. Consequently, all concerned practitioners (maxillo-facial surgeon, stomatologist, odontologist) have to aim the preservation of these patient's quality of life.

Expression of Runx2/Cbfa1/Pebp2αA During Angiogenesis in Postnatal Rodent and Fetal Human Orofacial Tissues

Transient expression of Runx2 is reported in endothelial cells and vascular smooth muscle cells during vessel formation in skin, stroma of forming bones and developing periodontal ligament, developing skeletal muscle cells, and fat tissue. The data suggest that Runx2 is expressed in a multipotential mesenchymal cell population that gives rise to various osseous and nonosseous cell lineages. Runx2/Cbfa1 is a transcription factor essential for cells of osteogenic and dentinogenic lineages. Here we examined expression of Runx2/Cbfa1 (all isotypes) in several nonskeletal cell types present in developing orofacial tissues of neonatal rodents and human fetuses with special emphasis on vessel formation. Sections obtained from heads or jaws of postnatal mice, hamster, and human fetuses were immunostained with monoclonal anti-Pebp2aA antibody. Mouse and human tissues were also examined by in situ hybridization. Sections of Runx2 null mutant mice with a LacZ reporter construct inserted in the Runx2 locus were stained for Runx2 promoter activity with anti-galactosidase. We found transient mRNA and protein expression in endothelial cells and in vascular smooth muscle cells of forming vessels in skin, alveoli of forming bone, and forming periodontal ligament. We also noticed weak and variable expression in some fibroblasts of embryonic skin, early differentiating cross-striated muscle cells, and differentiating fat cells. Runx2 is not an exclusive marker for chondrogenic, osteogenic, and dentinogenic tissues, but is much more widely present in an early multipotential mesenchymal cell population that gives rise to several other lineages.

Developmental gene expression profiling of mammalian, fetal orofacial tissue

The embryonic orofacial region is an excellent developmental paradigm that has revealed the centrality of numerous genes encoding proteins with diverse and important biological functions in embryonic growth and morphogenesis. DNA microarray technology presents an efficient means of acquiring novel and valuable information regarding the expression, regulation, and function of a panoply of genes involved in mammalian orofacial development. To identify differentially expressed genes during mammalian orofacial ontogenesis, the transcript profiles of GD-12, GD-13, and GD-14 murine orofacial tissue were compared utilizing GeneChip arrays from Affymetrix. Changes in gene expression were verified by TaqMan quantitative real-time PCR. Cluster analysis of the microarray data was done with the GeneCluster 2.0 Data Mining Tool and the GeneSpring software. Expression of >50% of the approximately 12,000 genes and expressed sequence tags examined in this study was detected in GD-12, GD-13, and GD-14 murine orofacial tissues and the expression of several hundred genes was up- and downregulated in the developing orofacial tissue from GD-12 to GD-13, as well as from GD-13 to GD-14. Such differential gene expression represents changes in the expression of genes encoding growth factors and signaling molecules; transcription factors; and proteins involved in epithelial-mesenchymal interactions, extracellular matrix synthesis, cell adhesion, proliferation, differentiation, and apoptosis. Following cluster analysis of the microarray data, eight distinct patterns of gene expression during murine orofacial ontogenesis were selected for graphic presentation of gene expression patterns. This gene expression profiling study identifies a number of potentially unique developmental participants and serves as a valuable aid in deciphering the complex molecular mechanisms crucial for mammalian orofacial development.

Multilineage Differentiation of Ectomesenchymal Cells Isolated from the First Branchial Arch

Cranial neural crest-derived ectomesenchymal cells may be pluripotent stem cells that are capable of generating a range of phenotypes. The fate of these cells appears to be determined in part by intrinsic genetic programs and also by the influence of extracellular signals in the local environment. The extent of lineage determination once neural crest cells have migrated to the first branchial arch is not clear, although branchial arch pattern is not thought to be the result of crest predetermination. The aim of the present study was to test the hypothesis that ectomesenchymal cells of the first branchial arch show properties of pluripotent stem cells, the lineage of which may be directed by specific molecular signaling. Ectomesenchymal cells were enzymatically isolated from the mandibular processes of BALB/c mice and maintained in an undifferentiated state while cultured with leukemia inhibitory factor or induced to differentiate by lineage-specific induction factors or growth conditions, including transforming growth factor beta, forskolin, and a mineralization-promoting medium. Morphological observations and immunocytochemistry demonstrated that cells could be induced to differentiate into smooth muscle cells, glial cells, and osteoblasts, respectively. In the presence of the mineralization-promoting medium, alkaline phosphatase activity increased significantly and mineralization nodules formed. The data reported support the concept that many, although not all, first branchial arch-derived ectomesenchymal cells show properties of multipotent stem cells, the subsequent fate of which can be influenced by induction factors and growth conditions. Some cells, however, showed a degree of commitment with respect to their fate. The possible application of first branchial arch-derived stem cells to tissue engineering of the orofacial tissues should involve consideration of the developmental stage of cell harvesting and the desired cell fate.

Aquaporin water channels AQP1 and AQP3, are expressed in equine articular chondrocytes

Chondrocytes exist in an unusual and highly variable ionic and osmotic environment in the extracellular matrix of articular cartilage. Alterations to the ionic and osmotic environment of chondrocytes influence the volume and ionic content of the cells, which, in turn, modifies the rate at which extracellular matrix macromolecules are synthesized and degraded. Thus, regulation of the water and solute content of chondrocytes will profoundly affect their anabolic and catabolic functions. The water content of cells is effectively influenced by the abundance of aquaporin (AQP) water channels. Recent studies have shown that several AQP water channel isoforms are expressed in chondrocytes from Meckel’s cartilage, developing teeth and other orofacial tissues. The aim of the present investigation was to determine if chondrocytes from equine articular cartilage express AQP water channels. Polyclonal antibodies to AQP1, AQP2 and AQP3 were used in conjunction with immunohistochemistry, immunoblotting and quantitative flow cytometry to determine if AQP1, AQP2 and AQP3 are expressed in equine articular chondrocytes. Our studies show that AQP1 and AQP3 are expressed by chondrocytes in articular cartilage in situ and in isolated chondrocytes. We found no evidence for expression of AQP2, the vasopressin-regulated water channel in chondrocytes. AQP1 and AQP3 may be involved in the transport of water and small solutes and osmotically active metabolites across the chondrocyte plasma membrane during volume regulatory behaviour. AQP1 may be involved in transporting metabolic water. AQP3 may participate in the transport of glycerol and structurally related molecules.

Aquaporin expression in developing human teeth and selected orofacial tissues.

The aquaporin (AQP) family of membrane channel proteins function as selective pores through which water, glycerol, and other small solutes cross the cell plasma membrane. To date, 11 members of this transporter family, designated AQP0-10, have been cloned and characterized in humans. The AQPs are differentially expressed in temporospatial patterns, where different AQPs demonstrate distinct tissue distributions that may reflect differing cell membrane transport functions. The purpose of this study was to evaluate AQP expression in the developing human teeth by RT-PCR and Western blot analysis. To access the generality of AQP expression, selected other orofacial tissues were studied by RT-PCR. The presence of all eleven human AQPs was screened in each tissue by RT-PCR. Positive amplification products were verified by direct DNA sequencing. AQPs 1, 3, 4, 5, 6, and 10 were identified by RT-PCR in developing teeth, and AQP1, 3, 5, and 6 were confirmed by Western blot analysis. AQP 4 was not detected by Western blot analysis, and we were unable to test for the recently identified AQP10 due to unavailability of antibodies. AQPs detected in other orofacial tissues by RT-PCR included gingiva (AQP3, 7, 10); Meckel's cartilage (AQP1, 3, 4, 5, 6); submandibular gland (AQP1, 3, 4, 5, 6, 7); masseter muscle (AQP1, 3, 4, 7, 8, 9,10); and infrahyoid muscle (AQP1, 3, 4,10). These results demonstrate that multiple aquaporins are expressed in developing teeth and in selected orofacial tissues.

Expression of c-Fos-like immunoreactive neurons in the supratrigeminal region in the rat following noxious stimulation of the orofacial tissues

This study was conducted to investigate immunohistochemically the expression of c-Fos in neurons around the trigeminal motor nucleus following application of mechanical force to a tooth, a mechanical pinch to the tongue, and paraformaldehyde injection into the periodontal ligament and masseter muscle. Following the application of all of these stimuli except pinching the tongue, a small number of c-Fos-like immunoreactive (Fos-LI) neurons were found in the ipsilateral supratrigeminal region. c-Fos expression was also detected in numerous neurons in the superficial laminae of the subnucleus caudalis in all experimental animals. Induction of c-Fos in the subnucleus caudalis and the supratrigeminal region indicates that Fos-LI neurons in the supratrigeminal region are involved in the processing of intraoral nociceptive signals.

Orofacial mechanoreceptors in humans: encoding characteristics and responses during natural orofacial behaviors

We used microneurography to characterize stimulus-encoding properties of low-threshold mechanoreceptive afferents in human orofacial tissues. Signals were recorded from single afferents in the infraorbital, lingual and inferior alveolar nerves while localized, controlled, mechanical stimuli were delivered to the facial skin, lips, oral mucosa and teeth. We likewise analyzed activity in these afferents during orofacial behaviors such as speech, chewing and biting. The afferents in the soft tissues functionally resemble four types described in the human hand: hair follicle afferents, slowly adapting (SA) type I and type II afferents and fast adapting (FA) type I afferents. Afferents in the facial skin, lips and buccal mucosa respond not only to contact with environmental objects, but also to contact between the lips, changes in air pressure generated for speech sounds, and to facial skin and mucosa deformations that accompany lip and jaw movements associated with chewing and swallowing. Hence, in addition to exteroceptive information, these afferents provide proprioceptive information. In contrast, afferents terminating superficially in the tongue do not signal proprioceptive information about tongue movements in this manner. They only respond when the receptive field is brought into contact with other intraoral structures or objects, e.g. the teeth or food. All human periodontal afferents adapt slowly to maintained tooth loads. Populations of periodontal afferents encode information about both which teeth are loaded and the direction of forces applied to individual teeth. Most afferents exhibit a markedly curved relationship between discharge rate and force amplitude, featuring the highest sensitivity to changes in tooth load at low forces (below 1 N). Accordingly, periodontal afferents efficiently encode tooth load when subjects first contact, hold, and gently manipulate food by the teeth. In contrast, only a minority of the afferents encodes the rapid and strong force increase generated when biting through food. We conclude, that humans use periodontal afferent signals to control jaw actions associated with intraoral manipulation of food rather than exertion of jaw power actions.

Effect of Brn-3a deficiency on parvalbumin-, calbindin D-28k-, calretinin- and calcitonin gene-related peptide-immunoreactive primary sensory neurons in the trigeminal ganglion

Immunohistochemistry for parvalbumin, calbindin D-28k, calretinin and calcitonin gene-related peptide (CGRP) was performed on the trigeminal ganglion and oro-facial tissues in Brn-3a wildtype and knockout mice at embryonic day 18.5 and postnatal day 0. In wildtype mice, the trigeminal ganglion contained abundant parvalbumin-, calbindin D-28k- and CGRP-immunoreactive neurons while the ganglion was almost devoid of calretinin-immunoreactive neurons. In Brn-3a knockout mice, a 63% decrease of parvalbumin-immunoreactive neurons was detected. In contrast, the absence of Brn-3a dramatically increased the number of calbindin D-28k-immunoreactive (3.5-fold increase) and calretinin-immunoreactive neurons (91-fold increase). The number of CGRP-immunoreactive neurons, however, was not altered by the Brn-3a deficiency. Cell size analysis indicated that loss of Brn-3a increased the proportions of small (<100 μm 2) parvalbumin-, calbindin D-28k- and CGRP-immunoreactive neurons while it decreased those of large (>200 μm 2) immunoreactive cells. Calretinin-immunoreactive neurons were either small or medium (100–200 μm 2) in mutant mice. The oro-facial tissues contained parvalbumin-, calbindin D-28k- and CGRP-immunoreactive fibers, but not calretinin-immunoreactive ones in wildtype mice. In Brn-3a knockout mice, the number of parvalbumin-immunoreactive fibers markedly decreased in the infraorbital nerve and parvalbumin-immunoreactive endings disappeared in the vibrissa. In contrast, the number of calbindin D-28k-immunoreactive fibers increased significantly in the infraorbital and mental nerves. In addition, calbindin D-28k-immunoreactive endings appeared in the vibrissa. As well, some fibers showed calretinin-immunoreactivity in the infraorbital nerve of the mutant. However, no obvious change of CGRP-immunoreactive fibers was observed in the oro-facial region of knockout mice. Taken together, our data suggest that Brn-3a deficiency has effects on the expression of neurochemical substances in the trigeminal ganglion.

Osteopontin-immunoreactivity in the rat trigeminal ganglion and trigeminal sensory nuclei

Osteopontin-immunoreactivity (OPN-ir) was examined in the oro-facial tissues and trigeminal sensory nuclei (principal sensory nucleus and spinal trigeminal nucleus) to ascertain the peripheral ending and central projection of OPN-containing primary sensory neurons in the trigeminal ganglion (TG). No staining was observed using mouse monoclonal anti-OPN antibody preabsorbed with recombinant mature OPN. OPN-immunoreactive (ir) peripheral endings were classified into two types: encapsulated and unencapsulated types. Unencapsulated endings were subdivided into two types: simple and complex types. Simple endings were characterized by the thin neurite that was usually devoid of ramification. These endings were seen in the hard plate and gingiva. The complex type was characterized by the thick ramified neurite, and observed in the vibrissa, hard palate, and molar periodontal ligament. Encapsulated endings were found only in the hard palate. The trigeminal sensory nuclei contained OPN-ir cell bodies and neuropil. The neuropil was devoid of ir in laminae I and II of the medullary dorsal horn (MDH), and had various staining intensities in other regions of the trigeminal sensory nuclei. Transection of the infraorbital and inferior alveolar nerves caused an increase of OPN-ir intensity in ipsilateral TG neurons. The staining intensity of the neuropil also increased in the trigeminal sensory nuclei ipsilateral to the neurotomy excepting laminae I and II of the MDH. The present study indicates that OPN-ir primary sensory neurons in the TG innervate encapsulated and unencapsulated corpuscular endings. Such neurons probably project their central terminals to the trigeminal sensory nuclei except for the superficial laminae of the MDH.

TrkA modulation of developing somatosensory neurons in oro-facial tissues: tooth pulp fibers are absent in trkA knockout mice

To investigate the nerve growth factor requirement of developing oro-facial somatosensory afferents, we have studied the survival of sensory fibers subserving nociception, mechanoreception or proprioception in receptor tyrosine kinase (trkA) knockout mice using immunohistochemistry. trkA receptor null mutant mice lack nerve fibers in tooth pulp, including sympathetic fibers, and showed only sparse innervation of the periodontal ligament. Ruffini endings were formed definitively in the periodontal ligament of the trkA knockout mice, although calcitonin gene-related peptide- and substance P-immunoreactive fibers were reduced in number or had disappeared completely. trkA gene deletion had also no obvious effect on the formation of Meissner corpuscles in the palate. In the vibrissal follicle, however, some mechanoreceptive afferents were sensitive for trkA gene deletion, confirming a previous report [Fundin et al. (1997) Dev. Biol. 190, 94–116]. Moreover, calretinin-positive fibers innervating longitudinal lanceolate endings were completely lost in trkA knockout mice, as were the calretinin-containing parent cells in the trigeminal ganglion. These results indicate that trkA is indispensable for developing nociceptive neurons innervating oral tissues, but not for developing mechanoreceptive neurons innervating oral tissues (Ruffini endings and Meissner corpuscles), and that calretinin-containing, trkA dependent neurons in the trigeminal ganglion normally participate in mechanoreception through longitudinal lanceolate endings of the vibrissal follicle.

The importance of stimulus site and intensity in differences of pain-induced vascular reflexes in human orofacial regions

Studies in anaesthetized animals have indicated that noxious stimulation may produce marked blood flow changes in various orofacial structures, but the influence of painful stimulation on the blood flow regulation of the orofacial area of humans has been studied only to a limited extent. The purpose of this investigation was to study whether there are differences in temporal and spatial patterns of pain-induced vasoactive reflexes between various orofacial regions and hand in healthy human volunteers. Dynamic changes in blood flow in various orofacial regions elicited by painful stimulation of the tooth and finger were measured by means of Laser Doppler imaging (LDI) and computer-assisted infrared thermography (IRT). Blood flow of the finger was recorded by laser Doppler flowmetry (LDF) and plethysmography (PLET). During both stimulus paradigms there was a transient elevation in heart rate (HR) and blood pressure (BP). At the same time there was a significant blood flow decrease in the finger (LDF, PLET) and in the nose (LDI, IRT). In contrast to tooth stimulation, finger stimulation caused a more marked blood flow reduction in the finger. Only high intensity tooth stimulation, but not finger stimulation, caused a long-lasting vasodilatation both in lower and upper lip. The blood flow changes in the lips were not correlated with changes in systemic blood pressure or heart rate. In the cheek, there were no marked flow changes during either finger or tooth stimulation. These data indicate that painful tooth (regional) stimulation, but not finger (remote) stimulation, can induce a long-lasting vasodilatation in parts of orofacial tissues which cannot be explained by changes in central cardiovascular parameters. This tooth-stimulation-induced blood flow increase supports the hypothesis of a special vasodilator reflex mechanism in the orofacial area. Furthermore, tooth-stimulation-induced vasoconstriction in the nose and dilatation in the lips indicate that separate vasoactive reflex mechanisms may exist for different orofacial regions.

Peptide 19-immunoreactive primary sensory neurons in the rat trigeminal ganglion

Peptide 19-immunoreactivity (PEP 19-IR) was examined in the trigeminal ganglion (TG) of the adult rat. A half of TG neurons were immunoreactive (IR) for PEP 19. PEP 19-IR neurons were mostly medium-sized to large. 66% of TG neurons >600 μm 2 and 38% of those in the range 300–600 μm 2 showed the IR. TG neurons <300 μm 2 were mostly devoid of PEP 19-IR (86%). A double immunofluorescence method revealed the coexpression of PEP 19 and calcium-binding proteins. 31% and 16% of PEP 19-IR neurons exhibited parvalbumin- and calbindin D-28k-IRs, respectively. Conversely, a half of parvalbumin- (53%) and calbindin D-28k-IR (55%) neurons coexpressed PEP 19-IR. PEP 19-IR neurons were mostly IR for S100 (91%) and 80% of S100-IR neurons showed PEP 19-IR. Virtually all (99%) PEP 19-IR neurons were devoid of calcitonin gene-related peptide (CGRP)-IR. The molar tooth pulp contained PEP 19-IR nerve fibers. In the root pulp, PEP 19-IR nerve fibers projected straight until they reached the coronal pulp. Accompanied by blood vessels, these nerve fibers ascended toward the pulp horn. They formed nerve plexuses in the subodontoblastic layer, and reached the base of the odontoblastic layer. However, PEP 19-IR nerve fibers could not be observed within the odontoblastic layer, predentine or dentine. The distribution of these nerve fibers was similar to that of parvalbumin-IR ones. In the TG, PEP 19-IR was found in 34% of primary sensory neurons retrogradely labeled from the molar tooth pulp. 80% of PEP 19-IR tooth pulp TG neurons coexpressed parvalbumin-IR. An immunoelectron microscopic method revealed that a half of radicular axons showed PEP 19-IR. 80% of myelinated axons exhibited PEP 19-IR, whereas 20% of unmyelinated ones showed the IR. In the subodontoblastic layer, PEP 19-IR nerve fibers mostly lost myelin sheath or Schwann cell ensheathment. At the base of the odontoblastic layer, PEP 19-IR neurites made close contact with odontoblasts. PEP 19-IR nerve endings could not be observed in other oro-facial tissues. The coexpression of PEP 19 and CaBPs suggests that low-threshold mechanoreceptors contain PEP 19-IR in the TG. It is also likely that PEP 19-IR TG neurons include myelinated nociceptors.

Tissue Engineering And Dentistry

This article assesses the current state of the art of tissue engineering and its applications in dentistry, especially in the reconstruction and repair of orofacial tissues, including bone and oral mucosa, for the restoration of function and improved cosmetics. The article discusses at length the tissue engineering of bone and cartilage, including guided tissue techniques, in which some of the most interesting advances in the field are being made.

Oral plasmablastic lymphoma in previously undiagnosed HIV disease

Non-Hodgkin’s lymphoma is the second most common HIV-associated malignancy. This report details a case of the recently described entity plasmablastic lymphoma of the mouth in a patient who was later found to have severe HIV disease. The tumor manifested as a large ulcerated mass of the left maxillary alveolus, causing bony destruction and tooth mobility. Histologic examination of lesional tissue revealed a lymphoid tumor with a high proliferation rate containing lymphoplasmacytoid cells that were reactive to the plasma cell marker VS38c but not to CD20 or CD79a; these are features of the recently reported non-Hodgkin’s lymphoma termed plasmablastic lymphoma. This is only the second report of an unusual tumor that has a predilection for the orofacial tissues. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:730-4)

Noma (cancrum oris): questions and answers.

Noma (cancrum oris) is an infectious disease which destroys the oro-facial tissues and other neighboring structures in its fulminating course. It affects predominantly children aged 2-16 years in sub-Saharan Africa where the estimated frequency in some communities may vary from one to seven cases per 1000 children. The key risk factors are poverty, malnutrition, poor oral hygiene, deplorable environmental sanitation, close residential proximity to livestock, and infectious diseases, particularly measles. Malnutrition acts synergistically with endemic infections in promoting an immunodeficient state, and noma results from the interaction of general and local factors with a weakened immune system as the common denominator. Acute necrotizing gingivitis (ANG) is considered the antecedent lesion. Current studies suggest that evolution of ANG to noma requires infection by a consortium of microorganisms with Fusobacterium necrophorum and Prevotella intermedia as the suspected key players. Without appropriate treatment, mortality rate is 70-90%. Survivors suffer the two-fold affliction of oro-facial disfigurement and functional impairment. Reconstructive surgery of the resulting deformity is time-consuming and financially prohibitive for the victims who are poor.

C-fiber depletion alters response properties of neurons in trigeminal nucleus principalis.

The effects of C-fiber depletion induced by neonatal capsaicin treatment on the functional properties of vibrissa-sensitive low-threshold mechanoreceptive (LTM) neurons in the rat trigeminal nucleus principalis were examined in adult rats. Neonatal rats were injected either with capsaicin or its vehicle within 48 h of birth. The depletion of unmyelinated afferents was confirmed by the significant decrease in plasma extravasation of Evan's blue dye induced in the hindlimb skin of capsaicin-treated rats by cutaneous application of mustard oil and by the significant decrease of unmyelinated fibers in both the sciatic and infraorbital nerves. The mechanoreceptive field (RF) and response properties of 31 vibrissa-sensitive neurons in capsaicin-treated rats were compared with those of 32 vibrissa-sensitive neurons in control (untreated or vehicle-treated) rats. The use of electronically controlled mechanical stimuli allowed quantitative analysis of response properties of vibrissa-sensitive neurons; these included the number of center- and surround-RF vibrissae within the RF (i.e., those vibrissae which when stimulated elicited >/=1 and <1 action potential per stimulus, respectively), the response magnitude and latency, and the selectivity of responses to stimulation of vibrissae in different directions with emphasis on combining both the response magnitude and direction of vibrissal deflection in a vector analysis. Neonatal capsaicin treatment was associated with significant increases in the total number of vibrissae, in the number of center-RF vibrissae per neuronal RF, and in the percentage of vibrissa-sensitive neurons that also responded to stimulation of other types of orofacial tissues. Compared with control rats, capsaicin-treated rats showed significant increases in the response magnitude to stimulation of surround-RF vibrissae as well as in response latency variability to stimulation of both center- and surround-RF vibrissae. C-fiber depletion also significantly altered the directional selectivity of responses to stimulation of vibrissae. For neurons with multiple center-RF vibrissae, the proportion of center-RF vibrissae with net vector responses oriented toward the same quadrant was significantly less in capsaicin-treated compared with control rats. These changes in the functional properties of principalis vibrissa-sensitive neurons associated with marked depletion of C-fiber afferents are consistent with similarly induced alterations in LTM neurons studied at other levels of the rodent somatosensory system, and indeed may contribute to alterations previously described in the somatosensory cortex of adult rodents. Furthermore, these results provide additional support to the view that C fibers may have an important role in shaping the functional properties of LTM neurons in central somatosensory pathways.

Necrotising Infection of the Orofacial Tissues in Neonates (Noma Neonatorum): Case report

Noma neonatorum should be differentiated from noma, in that it is typically a disease of seriously ill premature infants whose birth weight was low, and is caused by Pseudomonas aerugenosa septicaemia. We know of only two case reports of noma neonatorum involving newborn infants born at full term, so we report here another case of noma neonatorum in a neonate born at full term. In addition we describe the differences between noma neonatorum and noma (cancrum oris), a clinically related entity.