The Source of Lactic Acid in Experimental Sinusitis

Increased levels of L-lactate were found in secretions of the maxillary sinus in experimental sinusitis in rabbits. Analysis of certain epithelial metabolic enzymes in purulent sinusitis reveals an increased lactate dehydrogenase (LDH) activity in glands and epithelium. However, histochemically we could not find any decrease in oxidative enzyme capacity of the mucosal epithelium indicating an inadequate oxygen supply. In acute pneumococcal sinusitis, bacteria seem to resume a resting phase after a few days, and the lactate accumulation characteristic of the anaerobic milieu of the secretion appears to be mainly of leukocyte origin.

Mucosal Pathology of the Nose and Sinuses: A Study in Experimental Maxillary Sinusitis in Rabbits Induced by Streptococcus Pneumoniae, Bacteroides Fragilis, and Staphylococcus Aureus

Unilateral maxillary sinusitis was experimentally induced in New Zealand White rabbits with Streptococcus pneumoniae serotype 3, Bacteroides fragilis NCTC 9343, and Staphylococcus aureus V8 in order to study possible differences in the inflammatory response of the sinus and nasal mucosa at different time-intervals during a 12-week period of infection. The initial sinus mucosal response, most pronounced in pneumococcal sinusitis, was characterized by leukocytosis, epithelial desquamation, and squamous cell metaplasia. Tissue reactions at later intervals included fibrosis of lamina propria, gland involution, polyp formation, and bone remodelling, and were most pronounced in S. aureus and B. fragilis sinusitis. The nasal mucosa was altered with a redistribution of goblet cells, development of polyps in the ethmoidal region, involution of Bowman's glands and locally, areas of degenerated olfactory sensory epithelium. These findings endorse that the degree of local pathology depends on the infecting microorganism's specific pathogenetic factors. However, local tissue factors guiding the cellular inflammatory proliferative and regenerative processes are also of fundamental importance for the type of pathological changes occurring in an infected nasal or sinus mucosa.

Induction, Course, and Recovery of Maxillary Sinusitis: A Bacteriological and Histological Study in Rabbits

A bacteriological and histological study of acute pneumococcal sinusitis in rabbits was performed. The sinus ostium was blocked unilaterally and on the second day 108 Streptococcus pneumoniae type 3 were injected into the sinus cavity. The bacteriology of the sinus secretion and the morphological alterations of the sinus mucosa was determined 1, 2, 3 and 4 weeks after initiation of infection. Initially a pronounced mucosal infiltration of granulocytes and lymphocytes was found. Squamous cell metaplasia as well as areas of desquamated epithelium were also evident. This heavy inflammatory reaction gradually declined and after 4 weeks the epithelium appeared more normal, although goblet cells and subepithelial thickening, both associated with a more chronic infection, were found in certain areas. After 2 weeks, the initially reisolated pneumococci were replaced by a nonfermentative Gram-negative flora as well as anaerobic bacteria.

Local treatment of cricoid cartilage defects with rhBMP-2 induces growth plate–like morphology of chondrogenesis

Objective

The ultrastructural characteristics of new bone and cartilage, induced at the site of cricoid cartilage defects treated with rhBMP-2 in rabbits, were investigated.

Study Design and Setting

A cricoid defect model was used. Fifteen rabbits were randomly and equally divided into 3 groups. Four rabbits from each group were treated with rhBMP-2, while one rabbit from each group was used as control. The rabbits were killed 1, 2, or 4 weeks after surgery. The healing pattern of the laryngeal wound was evaluated by light and transmission electron microscopy.

Results

Mineralized collagen type I matrix, osteoblasts, and osteoclast-like cells were present as early as 1 week after surgery. Well-structured bone trabeculas and growth plate-like structures were present 4 weeks after surgery.

Conclusion

Intramembranous and endochondral osteogenesis take place at the site of cricoid cartilage defects treated with rhBMP-2. Progenitor cells of cricoid perichondrium form a growth plate-like structure similar to the epiphyseal growth plate.

Significance

This study reveals the pattern of BMP-2-induced repair of airway cartilage defects.

Effect of recombinant human BMP-2 on the repair of cricoid cartilage defects in young and adult rabbits: a comparative study

OBJECTIVE

The study evaluated the possible differences in the repair of cricoid cartilage defects treated with recombinant human BMP-2 in young and adult rabbits.

METHODS

A cricoid defect rabbit model was used. Thirty rabbits were randomly divided into eight groups. Two groups of young rabbits and two groups of adult rabbits were treated with rhBMP-2 delivered on an absorbable collagen sponge, while the other two groups of young rabbits and two groups of adult rabbits were used as controls. The rabbits were killed at 1 week or 4 weeks after surgery. A histomorphometric analysis and an evaluation of the expression of collagen types I, II, and X, and proliferating cell nuclear antigen as well as a study of distribution of calcified matrix, were performed.

RESULTS

rhBMP-2 induced a marked chondrogenesis in both experimental age groups. However, in young rabbits the newly formed cartilage appeared more elongate, and the length of perichondrium involved was greater. The host cricoid cartilage of adult rabbits was calcified in large areas and displayed a strong matrix expression of collagen type X as well as collagen type I in the perichondrium, compared to the cricoid of young rabbits. In spite of these differences no immunohistochemical differences were found in the newly formed cartilage of both age groups treated with rhBMP-2. The cricoid cartilage defect was filled with new bone at 4 weeks in both age groups treated with rhBMP-2. New bone tissue had a well-defined trabecular structure.

CONCLUSIONS

rhBMP-2 triggers appositional cartilage growth from the cricoid perichondrium of young rabbits more easily than from that of adult rabbits. The new bone induced by rhBMP-2 showed a similar immunohistochemical and morphological pattern in both age groups of rabbits.

Cell origin in experimental repair of cricoid cartilage defects treated with recombinant human bone morphogenetic protein-2

We determined the origin of new cartilage and new bone induced by recombinant human bone morphogenetic protein-2 (rhBMP-2) at the site of cricoid cartilage defects in rabbits randomly divided into eight groups. The cricoid cartilage was split vertically along the anterior midline and a strip was excised from the anterior part of the cricoid cartilage in all rabbits. The perichondrium from the anterior part of the cricoid cartilage was trimmed off in four groups; two groups treated with rhBMP-2 and two control groups. In four other groups, the anterior perichondrium was detached and used as a flap with two groups treated with rhBMP-2 and two groups serving as controls. The rabbits were killed 1 week or 4 weeks after surgery. The larynges were removed, fixed and sectioned, and the sections were stained for light microscopy using various cytochemical and immunological techniques. New cartilage was only present close to the host perichondrium adherent to cricoid cartilage in rabbits treated with rhBMP-2. New bone was present 4 weeks after surgery, although calcified matrix and alkaline phosphatase activity could be detected at the site of cricoid defects as early as 1 week after surgery. The cell proliferation marker Ki-67 was strongly expressed in granulation tissue and bone marrow, and it was moderately expressed in muscles adjacent to the cricoid cartilage in rhBMP-2-treated specimens. BMP receptors were strongly expressed in cartilage and moderately expressed in adjacent muscles. We conclude that new cartilage originates from the mesenchymal progenitor cells of host perichondrium adherent to cricoid cartilage in rabbits treated with rhBMP-2. New bone may originate from local muscle.

Recombinant human bone morphogenetic protein-2 enhances experimental laryngotracheal reconstruction in rabbits

OBJECTIVE

Bone morphogenetic protein-2 offers potential benefits for cartilage regeneration. We investigated the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the regeneration of laryngeal cartilage and respiratory epithelium in a rabbit model.

MATERIAL AND METHODS

We used a cricoid defect rabbit model. Twenty-four rabbits were randomly divided into four equal groups. Two groups were treated with 5 microg of rhBMP-2 delivered on an absorbable collagen sponge and the other two groups were used as controls. One group of treated rabbits and one group of control rabbits were euthanized 1 week after surgery, while the others were euthanized 4 weeks after surgery. The healing pattern of the laryngeal wound was evaluated by means of histomorphometry.

RESULTS

Regeneration of both the epithelial layer and cartilage was significantly better in rabbits treated with rhBMP-2. Four weeks after surgery, the cricoid cartilage defect was completely repaired by new cartilage and new bone in rabbits treated with rhBMP-2. Furthermore, the lining respiratory epithelium healed more rapidly in treated rabbits.

CONCLUSION

rhBMP-2, delivered via an absorbable collagen sponge, induces complete regeneration and repair of rabbit cricoid cartilage defects. It also induces faster relining and regeneration of airway epithelium than in control rabbits.

Structural characteristics of repair tissue of cricoid cartilage defects treated with recombinant human bone morphogenetic protein-2

We examined the structural characteristics of repair tissue induced by recombinant human bone morphogenetic protein-2 in a rabbit model of laryngotracheal reconstruction. Twenty-four New Zealand White rabbits were randomly divided into four groups of six rabbits. Two groups were treated with recombinant human bone morphogenetic protein-2 delivered on an absorbable collagen sponge, while two groups were used as controls. Rabbits were euthanized at 1 and 4 weeks after surgery. The larynx was removed, fixed, and sectioned. The sections were stained with hematoxylin-eosin, safranine O/fast green, and immunostained with an antibody for tissue inhibitor of metalloproteinases-1. In rabbits treated with bone morphogenetic protein-2, the defects were filled with new cartilage and bone at 4 weeks after surgery. There were no discontinuities or gaps at the margins of the cartilage defects. Proteoglycans were synthesized in new cartilage in rabbits treated with bone morphogenetic protein-2, and were present 4 weeks after surgery. The general aspects of the vascular pattern and the pattern of tissue inhibitor of metalloproteinases-1 expression were similar in control and treated rabbits, both 1 week and 4 weeks after surgery. The repair tissue induced by recombinant human bone morphogenetic protein-2 consisted of new cartilage and bone perfectly integrated with host tissue at the site of the cricoid cartilage defects. This new cartilage was able to mature and produce proteoglycans.

Apoptosis in meatal skin, cholesteatoma and squamous cell carcinoma of the ear

Apoptosis in normal meatal skin, cholesteatoma and squamous cell carcinoma (SCC) of the ear was investigated by using morphological analysis and in-situ specific labelling of fragmented DNA. In meatal skin, apoptotic cells were localized mainly in the granular layers, but were not so restricted in cholesteatoma, while in SCC they were even more dispersed. The apoptotic index (AI) was low (1.59 +/- 0.10 SEM) in normal skin. It was increased in cholesteatoma (2.09 +/- 0.11), and was intermediate in SCC (1.72 +/- 0.14). By contrast, the mitotic index (MI) increased from 0.19 +/- 0.02 in normal skin, to 0.25 +/- 0.01 in cholesteatoma and to 0.25 +/- 0.02 in SCC. Our findings indicate that apoptosis is involved in the epithelial homeostasis of meatal skin, cholesteatoma and SCC of the ear. The hyperproliferation of epithelial cells in cholesteatoma is counteracted by an increased apoptosis rate, while in SCC the increased cell proliferation without a compensatory increase in apoptosis may be associated with the malignant transformation.

Lectin expression during wound healing of the rabbit sinus mucosa: a study of regenerating epithelium and early polyp formation

Lectin expression during wound healing of the rabbit sinus mucosa was examined. Positive UEA-I staining was evident on squamous or cuboidal as well as columnar regenerating epithelial cells (RE cells). PNA staining of columnar RE cells first became evident after neuraminidase treatment, while squamous or cuboidal RE cells stained positively with PNA alone. Fucosylation within RE cells thus occurred from a relatively early period, and sialylation followed at later stages. Ingrowing epithelial cells of early polyp formation stained negatively with UEA-I, indicating that unfucosylated RE cells may represent aberrant cellular behavior. We concluded that these patterns of lectin staining indicate a functional maturation as well as an integration of regenerating mucosa.

Edema formation in the rat larynx

In the rat larynx, plasma exudation and edema formation were studied by light and electron microscopy after i.v. injections of the mast cell activator compound 48/80, substance P, and capsaicin. The morphological effects of substance P and capsaicin on connective tissue mast cells in vivo were also examined. Of the drugs tested, only compound 48/80 degranulated the connective tissue mast cells. All drugs induced a subepithelial plasma exudation in the subglottic region, with edema in the lamina propria and widened intraepithelial intercellular spaces, though the tight junction regions seemed intact. In the epiglottis, 10 min after compound 48/80 injection, there was edema in the lamina propria on the lingual side, with an intact and tight epithelial lining. No morphological sign of edema was found in the epiglottis after injection of substance P or capsaicin. The pronounced effect found in the epiglottic region after compound 48/80 injection was due to the release of mediators such as histamine and 5-hydroxytryptamine from the connective tissue mast cells. This study supports the belief that substance P in vivo mediates an increased vascular permeability by a direct effect on the blood vessels - a mechanism distinct from mast cell degranulation.

Changes in glycoconjugate expression of the sinus mucosa during experimental sinusitis: a lectin histochemical study of the epithelium and goblet cell development

Lectin expression in both normal and inflamed sinus mucosa in rabbit was investigated histochemically. A different staining pattern was observed in the inflamed mucosa, i.e. the degree of staining reactivity with Canavalia ensiformis (ConA) decreased, whereas staining with Ulex europaeus agglutinin-I (UEA-I), Arachis hypoga (PNA) with neuraminidase pretreatment and Triticum vulgaris (WGA) intensified, indicating an enhanced fucosylation as well as sialylation. Goblet cells were stained with UEA-I, WGA, PNA and PNA with neuraminidase pretreatment, but scarcely with ConA. Positive PNA staining of basal cells and epithelial secretory granules was observed in the inflamed mucosa, especially close to areas where goblet cell development was prolific. It was therefore assumed that basal cells can differentiate into goblet cells-through epithelial secretory cells accompanied by sialylation and/or sulphonation of their mucins. It is concluded that the changes in glycoconjugate expression as well as goblet cell development in the inflamed mucosa are of importance for both local host resistance and defence mechanisms against microorganisms during the early stages of the inflammatory process.

Recurrent primary pleomorphic adenomas of salivary gland origin: intrasurgical rupture, histopathologic features, and pseudopodia

BACKGROUND

The rate of tumor recurrence after surgery for benign salivary gland pleomorphic adenoma varies considerably in different clinical settings and seems to depend to a great extent on the surgical technique used. The importance of tumor spillage for subsequent recurrence has recently been questioned. The current follow-up study was undertaken to ascertain whether intrasurgical rupture, tumor spillage, or any histopathologic feature might have had an impact on the rate of recurrence.

METHODS

The medical records of all 255 patients operated on for benign salivary gland pleomorphic adenoma between the years 1974 and 1993 at the Department of Otorhinolaryngology, Huddinge University Hospital, were reviewed. All patients alive in April 1995 (n = 230) were sent a simple questionnaire. Two hundred thirteen of these patients received follow-up. All cases of tumor recurrence after surgery or intrasurgical rupture of the tumor capsule were reviewed histopathologically.

RESULTS

Two (7.1%) of the 28 patients who had macroscopic capsule rupture during surgery experienced recurrence at a later stage. This was not a statistically higher rate than the 4.1% recurrence rate for the rest of the material. As many as 5 of the 9 primary tumors that subsequently recurred (56%) sent fingerlike tumor extensions or pseudopodia outside the pseudocapsule. The rate of occurrence of such structures was statistically higher than that of the tumors that ruptured during surgery (25%) and the examined uncomplicated cases (8%).

CONCLUSIONS

Occurrence of pseudopodia--microscopic fingerlike formations of tumor tissue that extend beyond the main lump of the tumor--is a significant risk factor for local recurrence.

Early stages in the development of goblet cells in the paranasal sinuses: a multimethodological study in the rabbit

To evaluate the pattern of goblet cell differentiation in sinus mucosa in response to external stimuli, New Zealand White rabbits were subjected to either experimental sinusitis or topical capsalcin application. Sinus mucosa was examined by light microscopy after serial sectioning, whole-mount preparation or immunohistochemistry. The mucosa was also examined by electron microscopy after perfusion fixation or high-pressure freezing. While goblet cells were normally very scarce in the healthy rabbit maxillary sinus mucosa, such cells were frequent after experimental sinusitis or topical capsaicin application. The process of goblet cell differentiation seems to follow a sequential path where serous secretory cells start to produce an increasing amount of mucous granules which appear electron lucent after conventional fixation. Parallel to this shift in secretion production, the cell assumes a bulging appearance after conventional fixation. It is concluded that newly formed goblet cells are recruited from intermediate secretory cell stages rather than from ciliated cells.

Effects of experimental Mycoplasma pulmonis infection on sensory neuropeptides and airway mucosa in the rat

The effect of airway infection on neurogenic inflammation is not known. The present study examines the effect of Mycoplasma pulmonis infection on the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) in the trigeminal ganglion and in the mucosa of the nose and trachea in rats. We compared germ-free (GF), conventionally raised (CV) and specific pathogen-free (SPF) rats. The concentrations of SP and CGRP in the nasal mucosa were assessed with immunohistochemistry, and their prohormonal transcripts in the trigeminal ganglion were assessed with Northern blot. Mucosa was also processed for light microscopy and electron microscopy. SP-like immunoreactivity was greater in the nasal mucosa of infected animals than in uninfected controls. CGRP-like immunoreactivity was greater in the nasal septum, but not in the nasal turbinate, of infected than uninfected animals. In contrast, no change was evident in the expression levels of the prohormonal transcripts in the trigeminal ganglion. Infected nasal and tracheal mucosa was oedematous and locally infiltrated with inflammatory cells. In the nose of uninfected GF rats, subepithelial lymphoid aggregations were scarce and appeared inactive. We conclude that Mycoplasma pulmonis infection results in increased immunoreactivity of substance P, probably within nerves. There was no clear evidence of increased synthesis of the precursors of substance P and calcitonin gene-related peptide.

Expression of transforming growth factor-alpha and epidermal growth factor receptor in middle ear cholesteatoma

To study the possible autocrine growth stimulation of cholesteatoma epithelium, the expression of transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) in middle ear cholesteatoma was investigated by immunohistochemical staining techniques. Twenty cholesteatoma samples obtained at operation and six normal skin specimens collected from the external ear canal were used in the study. Immunostaining for TGF-alpha showed a diffuse cytoplasmic staining pattern. It was weakly expressed in the basal layer of the normal epidermal epithelium but was more strongly expressed in all cholesteatoma specimens. EGFR showed a dot-like/diffuse cytoplasmic and cell membrane staining pattern. EGFR-positive cells were seen in the basal layer of normal epidermis. In the cholesteatoma specimens, expression of EGFR was not only confined to the basal layer but persisted into the upper layers of the epithelium. Our findings indicate that an autocrine growth stimulation by TGF-alpha and EGFR may contribute to the unrestrained growth of cholesteatoma epithelium in the middle ear cavity.

Zenker's diverticulum--a historical review and trends in therapy

More than 200 years have passed since the pulsion diverticulum of hypopharynx was first described. This paper reviews different opinions on its etiology over the centuries. The German pathologist F.A. von Zenker, who successfully pursued research on a variety of topics, is often associated with this diverticulum through his classical work from 1867 "Krankheiten des Oesophagus", which deals with the pathogenesis and clinical presentations of this herniation of the posterior mucosal wall. Numerous surgical techniques, which have been practised mainly during this century, are also reviewed. Different options of endoscopic surgery, which is presently the preferred approach at many medical centers, are described and discussed. Our own experience of endoscopic surgery in patients with Zenker's diverticulum is also presented.

A comparison of morphological effects on the rabbit nasal and sinus mucosa after surgical denervation and topical capsaicin application

In order to study morphological effects on the nasal and sinus mucosa, New Zealand White rabbits underwent either unselective, regional sectioning of sensory and parasympathetic nerve branches or topical treatment of the mucosa with capsaicin. Ten days after treatment, mucosal specimens were analyzed by light and electron microscopy. Immunohistochemistry was used to evaluate neuropeptides present, in particular substance P, calcitonin gene-related peptide, vasoactive intestinal peptide and neuropeptide Y. In surgically denervated rabbits, mucosal glands were found to be enlarged and contained an increased number of zymogen granules having a bipartite substructure. Topical capsaicin application caused localized epithelial changes in the sinus mucosa and maxilloturbinal region of the nose, including clotting of cilia and an increased number of goblet cells. Reduced amounts of all neuropeptides investigated were found in the surgically denervated animals, while topical capsaicin treatment had only marginal effects on the mucosal neuropeptide content. The morphological changes observed after surgical denervation suggest an imbalance between neural stimulation and secretory capacity of the mucosal glands. These findings could explain the difference in clinical effect noted between sectioning of the vidian nerve and topical treatment with capsaicin in patients with perennial rhinitis.

Experimentally induced polyps in the sinus mucosa: a structural analysis of the initial stages

To document polyp formation in the sinus mucosa, the authors of this study subjected New Zealand white rabbits to different modes of manipulation intended to induce inflammation of the maxillary sinus. These manipulations included a combination of bacterial infection and mechanical trauma, the deposition of agarose into the sinus cavity, and the deposition of N-formyl-methionyl-leucyl-phenylalanine, a chemotactic peptide, into the sinus cavity. A majority of animals developed polyps, which were examined by light and electron microscopy. Polyp formation appears to involve epithelial disruption and the migration of immature branching epithelium. While part of the migrating epithelium eventually covers the mucosal defect, other branches spread into the underlying connective tissue, where intraepithelial microcavities with a differentiated, ciliated lining are formed. Fusing cavities separate the developing polyp body from the adjacent mucosa. With the described method, mucosal polyps can be induced with high reproducibility.

Antigen expression of epithelial markers, collagen IV and Ki67 in middle ear cholesteatoma. An immunohistochemical Study

The expression of epithelial markers (cytokeratins, Filaggrin, BerEp4 and EMA), collagen IV and Ki67 was studied immunohistochemically in cholesteatoma and compared with that in epidermis of meatal skin, squamous epithelium of eardrum and simple epithelium of middle ear mucosa. MNF116 (cytokeratin 10, 17, 18) stained the full layer of normal epithelium and all cholesteatoma specimens. CK10 and Filaggrin were expressed in the upper layer of epidermis but more diffusely in cholesteatoma. BerEp4 was found in the basal layer of normal epithelium but was detected in most epithelial cells in cholesteatoma matrix. Variability was observed in EMA and CK14 immunostaining. Collagen IV was localized in the basement membrane of normal epithelium with a continuously staining pattern, an observation also made in the cholesteatomas studied. However, in one of these small areas the basement membrane was not stained with collagen IV. Ki67 was expressed in nuclei of the cells in the basal layer of normal epithelium but extended to epithelial cells in the upper layers of cholesteatoma matrix. The results of the present study indicate that the expression pattern of epithelial markers in cholesteatoma corresponds to that in normal epidermis. The increasing expression of BerEp4 and Ki67 confirms the hyperproliferative nature of cholesteatoma. Whether or not the lack of expression of collagen IV in one of the cholesteatomas reflects a true degradation of the basement membrane needs further investigation in extended materials.

Formation of mucosal polyps in the nasal and maxillary sinus cavities by infection

Unilateral maxillary sinusitis was experimentally induced in New Zealand White rabbits with Streptococcus pneumoniae serotype 3, Bacteroides fragilis NCTC 9343, and Staphylococcus aureus V8. In another group of rabbits, sinusitis was induced by blocking of the sinus ostium only. Bacteriologic and light microscopic analysis was performed after 5 days to 1 month. Granulation-like polyps developed after deep mucosal inflammatory trauma initiating fibroblast proliferation, angiogenesis, and epithelial migration to cover the polyp. In regions of a more superficial trauma-characterized by epithelial desquamation and fibroblast growth-proliferation and differentiation of basal cells resulted in the formation of microcavities dissecting off edematous polyps. Polyps could be found in all sinusitis groups, irrespective of inducing agent. The cellular events of polyp formation appear to be the result of a continuous inflammatory reaction and are not directly related to the presence of a certain microorganism. Instead, the potential of any microorganism to induce a deep mucosal trauma or epithelial desquamation seems essential for its ability to initiate polyp formation.

Mucosal fine structure in experimental sinusitis

Rabbit maxillary sinuses were inoculated with Streptococcus pneumoniae and Bacteroides fragilis, and the histologic response in the sinus mucosa was observed over a 12-week period. An increased height of the cylindric cells and hyperplasia of the basal cells were frequent findings irrespective of the pathogen inoculated. The disease was found to influence the character of the secretory product from epithelial secretory cells and to degranulate the subepithelial glands. Ciliary loss was a transitional finding. A reduction in the number of mitochondria, the occurrence of deformed short microvilli, and cytoplasmic blebbing were seen in the cells devoid of normal cilia. It is inferred from this study that pneumococcal sinusitis in rabbits is a self-limiting process, and the mucosal sequelae of the acute infection are persisting goblet cells, slight focal fibrosis, and edema. Inoculation with B fragilis produces a chronic inflammatory process, with infiltration of mononuclear cells, luminal dilatation of the glands exhibiting zymogen granule depletion, and an increased thickness of the whole mucosal layer.

Regeneration of maxillary sinus mucosa following surgical removal. Experimental study in rabbits

A rapid regeneration of the epithelium takes place in the maxillary sinus in rabbits after experimental operative removal of the mucosa. Two weeks postoperatively the previously denuded areas have reepithelialized. The subepithelial glands, however, do not seem to regenerate. The normal sinus mucosa contains numerous serous glands in the lamina propria, but in the regenerated mucosa these glands are replaced by dense connective tissue. Atypical glands and polyp formations are sometimes encountered, but goblet cells are sparse. Furthermore, the sinus cavity on the operated side is reduced in size compared with the nonoperated side because of fibrosis and periosteal reactions including bone degradation and neogenesis. This study indicates that although the mucosa is reepithelialized within 2 weeks, the regeneration of the lamina propria is incomplete, and reactive cellular processes such as bone remodeling, fibroblast proliferation, and formation of polyps and "atypical glands" are characteristic of regenerating mucosa.

Lysozyme and lactoferrin in human maxillary sinus mucosa during chronic sinusitis. An immunohistochemical study

Immunohistochemistry was used to study the localization of lysozyme (LZ) and lactoferrin (LF) in the human sinus mucosa during recurrent and chronic sinusitis. Serous cells of submucosal mixed glands and polymorphonuclear leukocytes both displayed a strongly positive staining reaction to both LZ and LF in the normal mucosa. A positive though weak staining for LZ and LF could also be found occasionally within goblet cells. In the mucosa from patients with recurrent or chronic sinusitis, the staining reaction to LZ appeared to intensify in goblet cells. Furthermore, an increased immunoreactivity of glands vis-à-vis LZ and LF was also noted occasionally. Atypical glands were frequently found in mucosa from patients with chronic sinusitis. The epithelium of these latter glands often showed an intense staining reaction to LF, but a rather weak reaction to LZ. The results of the present study suggest that the observed increase in LZ and LF secreting activity of goblet cells, epithelial cells and newly formed atypical glands may play a part in the defense mechanism of the sinus mucosa during the course of chronic sinusitis.

Cellular regeneration and recovery of the maxillary sinus mucosa. An experimental study in rabbits

Unilateral maxillary sinusitis was induced in 30 New Zealand White rabbits with Streptococcus pneumoniae or Bacteroides fragilis. In another group of 15 rabbits without infection, the sinus mucosa was surgically removed in defined areas. In both series, the sinuses were serially sectioned for histological analysis of the cellular regenerative capacity. In maxillary sinusitis induced by Bacteroides fragilis, an inflammatory and also reparative process involving all mucosal layers including the underlying periosteum was seen. The more superficial trauma as found in pneumococcal sinusitis eventually led to restitution ad integrum. Following surgical removal, the denuded sinus-lining was reepithelized by a flattened ciliated epithelium on a lamina propria displaying fibrosis and lacking serous glands. The restoration of the rabbit maxillary sinus mucosa after surgical trauma thus leads to structural abnormalities of the epithelium as well as the lamina propria, and these changes are likely to interfere with the normal function of the sinus mucosa.

Experimental maxillary sinusitis induced by Bacteroides fragilis. A bacteriological and histological study in rabbits

Experimental anaerobic maxillary sinusitis was induced in New Zealand White rabbits by blocking the ostium and inoculating Bacteroides fragilis, strain NCTC 9343. The animals were examined histologically and bacteriologically after 5 days, and 2, 3 and 4 weeks. All the infected sinuses displayed signs of moderate or severe inflammation throughout the study period. Ciliary damage and desquamation, hyperplasia and metaplasia of the epithelium were characteristic features. Furthermore, heavy leukocyte- and, particularly, round cell-infiltration, fibrosis, periosteal hyperplasia and bone degradation and -formation were also frequently encountered. The secretory cell count in the epithelium increased, including the regeneration of goblet cells. After 4 weeks no obvious recovery could be seen, and the inducing microorganism was re-isolated in the majority of cases. In comparison with experimental pneumococcal sinusitis, the B. fragilis infection exerts a more prolonged and severe inflammation.

Lactic acid isomers and fatty acids in sinus secretion: a longitudinal study of bacterial and leukocyte metabolism in experimental sinusitis

Concentrations of the two optic isomers of lactate (D- and L-form) as well as glucose, succinate, acetate, butyrate, isovalerate and valerate were examined in purulent sinus secretions. The samples were obtained from rabbit maxillary sinuses, experimentally infected with Streptococcus pneumoniae or Bacteroides fragilis. More soluble acids such as acetate displayed relatively low levels in the secretion, despite a high microbial production. A substantial increase in D-lactate concentration was found in secretions only the first day after induction of pneumococcal sinusitis, and not in bacteroides sinusitis. L-lactate levels were particularly high in secretions of a marked purulent character, and this isomer can be considered as indicator of anaerobic glycolysis in the leukocytes. Less diffusible fatty acids such as butyrate and isovalerate accumulated in the secretion, in spite of a relatively lower production rate, and are thus more reliable indicators of bacterial metabolism.

Experimental sinusitis in rabbits induced by aerobic and anaerobic bacteria: models for research in sinusitis

Experimental acute sinusitis can be induced in New Zealand white rabbits by Streptococcus pneumoniae serotype 3, or the anaerobe Bacteroides fragilis, after blocking of the sinus ostium. Histological examination of the sinus mucosa in both models reveals edema, dilated venules, leukocytic infiltration, goblet cell formation, as well as localized epithelial lesions. In comparison the bacteroides sinusitis enhances a more pronounced and long-lasting tissue reaction, including periosteal thickening and new bone formation. The sinus mucosal blood flow as measured with microspheres Sn113 is increased as compared to control side in pneumococcal sinusitis. An increased lactate concentration of sinus secretions as well as in the pathological sinus mucosa indicates an anaerobic metabolism. Furthermore, a decreased ATP-content of the sinus mucosa suggests an energy depletion which could impair epithelial function. The anaerobic milieu of the sinus secretion is probably created by the leukocytes as analyzed by the separation of the D- and L-form of lactate.

Occurrence of mast cells in relation to the distribution of nerve fibers in the rat larynx

The distribution of mast cells in the rat larynx was studied at a light microscopic level in relation to nerve fibers showing substance P (SP)- and calcitonin gene-related peptide (CGRP)-like immunoreactivity (-LI) and ultrastructurally in relation to unmyelinated nerve fibers. Connective tissue mast cells (CTMC), demonstrated by staining for avidin-peroxidase and immunohistochemical staining for 5-hydroxytryptamine (5-HT), were localized in the lamina propria. Alcian blue and toluidine blue revealed mast cells in the epithelium and the lamina propria. The mast cells showed similar regional differences in their distribution as fibers showing SP- and CGRP-LI. A large or moderate number of cells was found on the laryngeal side of the epiglottis, in the ventral recess and in the aryepiglottic folds. No mast cells were found in the vocal cords. In addition, a large number of cells showing 5-HT-LI were observed in the subglottic epithelium but not in the supraglottic and the glottic epithelia. Ultrastructurally and by use of SP- and CGRP-immunohistochemistry, nerve fibers were sometimes observed close to the mast cells. These findings may be of importance in the understanding of laryngeal pathophysiological events.

Mucosubstance histochemistry of the maxillary sinus mucosa in experimental sinusitis: a model study on rabbits

The histochemical properties of mucosubstances within the sinus mucosa were examined in rabbits affected with experimental sinusitis, induced either by blocking the maxillary sinus ostium (occlusion group) or in addition by an inoculation of Streptococcus pneumoniae (pneumococcal group). An increase in periodic acid-Schiff positive epithelial secretory cells was found, as well as regeneration of goblet cells in the epithelium from the 2nd week. The goblet cells proved to contain periodate-reactive acid mucins, particularly during the early stages, as well as periodate-unreactive, purely acid mucins which were prevalent throughout the study. Among the alcian blue positive goblet cells, 0-40% (usually 5-20%) contained acid sialomucins, while the rest stained positive for sulphomucins. The submucosal glands and the large lateral nasal and maxillary glands were not histochemically influenced by the induced inflammatory state. No obvious difference in the histochemical staining pattern was seen between the two groups. A comparative microbiological analysis of the groups was also included in the study.

Histopathological observations in chronic maxillary sinusitis

Biopsy samples from the maxillary sinus mucosa of patients with purulent, non-purulent and recurrent sinusitis were studied histologically and compared with those from a maxillary sinus of patients with no previous history of sinus disease on the side of sampling. Basement membrane thickening, atypical gland formation, goblet cell hyperplasia, mononuclear inflammatory cell infiltration and subepithelial oedema were observed in all groups irrespective of the appearance of the effusion. Although the inflammatory variables in selected areas of the mucosa seemed to show an increase in severity with the increasingly severe forms of sinusitis, neither the endoscopic mucosal appearance nor the nature of the sinus effusion corresponded to any specific histological pattern.

Motor and sensory fibers of the superior laryngeal nerve in the rat. A light and electron microscopic study

A quantitative and qualitative study of the superior laryngeal nerve (SLN) and its branches was performed on the intact nerve and after experimental denervation procedures. The distribution patterns of the myelinated fibers of the intact internal (SLNI) and external (SLNE) branches in the rat were unimodal with a fiber diameter range of 0.5-12 microns and with peaks at 2-4 microns. Numerous unmyelinated fibers, ranging in diameter from 0.1-2.3 microns, were evenly distributed all over the nerve. The SLNI contained no degenerated myelinated fibers after intracranial vagotomy, but about 25% of the unmyelinated fibers showed degenerative features. In the SLNE 2-10% of the myelinated fibers and about 25% of the unmyelinated fibers were degenerated after the same procedure. Extracranial vagotomy caused degeneration of nearly all fibers in the SLNI and SLNE. Single unmyelinated fibers appeared normal after this procedure. Occasional myelinated and a few unmyelinated fibers were degenerated after excision of the superior cervical ganglion. It is inferred from the results that a majority of the myelinated fibers in the SLN (96-99%) are sensory, with the cell bodies in the extracranial vagal ganglia. The SLNE was also found to be predominantly sensory, as only 2-10% of the myelinated fibers and about 25% of the unmyelinated fibers had their cell bodies in the brainstem. Single myelinated and a few unmyelinated fibers in both the SLNI and SLNE had their origin in the superior cervical ganglion.

Experimental acute sinusitis in rabbits. A bacteriological and histological study

A bacteriological and histological study of experimentally induced acute pneumococcal sinusitis was performed in 69 New Zealand White rabbits. The sinus ostium was blocked on one side on the first day of the experiment. On the second day, 10(7)-10(9) Streptococcus pneumoniae in 1 ml were injected into the same sinus cavity. Purulent sinusitis developed unilaterally in all rabbits. Histological examination of the sinus mucosa revealed edema, dilated venules, leukocytic infiltration of the mucosa as well as localized epithelial lesions. On staining with acridine orange at pH 4.0, the bacteria were observed in the secretion but not in the mucosa. When we used Streptococcus pneumoniae subjected to an animal passage, the bacteria were re-isolated in 9/10 infected sinuses. Neither sole occlusion of the ostium nor injection of pneumococci into a sinus cavity with a patent ostium resulted in a bacterial sinusitis. Obstruction of the sinus ostium and the use of a virulent Streptococcus pneumoniae strain were essential for the induction of sinusitis in rabbits.

Mucoepidermoid carcinoma in a minor salivary gland in childhood

Salivary gland neoplasms in childhood and adolescence are rare, especially in the minor salivary glands. Vasoformative tumours and pleomorphic adenomas appear to be the most common benign neoplastic salivary gland lesions in the pediatric age group. The distribution of various malignant histological types is not always consistent with that in the adult population, and they appear more often in girls than in boys. Only 17 cases have previously been documented. The clinical and histological picture of a case of palatal mucoepidermoid carcinoma in a 13-year-old girl is presented as well as a review of the literature on malignant salivary gland tumours in childhood.

DNA cytophotometry of acinic cell carcinoma and its relation to prognosis

Single-cell DNA cytophotometry has been assessed on histological sections or aspiration biopsy smears from 13 parotid acinic cell carcinomas and has been related to prognosis. The minimal follow-up was 6 years. Six ACC were well differentiated and seven moderately well differentiated. The modal DNA values of all tumours examined were in the diploid area. The number of nuclei above 2.5C DNA, expressing proliferative ability or aneuploidy, was low. A difference, too small to be of value for prognostic purposes, was found between the non-recurrent tumours (6%) and the metastasizing tumours (16%). The DNA levels measured in the present tumour material correspond to the concept of ACC as being a well differentiated neoplasm. The nuclear DNA pattern of these tumours would seem to be of minor prognostic significance with regard to survival time and/or potential for metastasis.

Paraganglia of the rat recurrent laryngeal nerve after long-term hypoxia: a morphometric and biochemical study

Paraganglia of the recurrent laryngeal nerve of rats exposed to hypoxia (10 +/- 0.5% O2) for 3 weeks became enlarged in volume by 2.6-fold. The volume densities of blood vessel lumen and endothelial cells were unchanged. The enlargement of the paraganglia was mainly attributed to hypertrophy of the dense-cored vesicle-containing cell. Concerning the profile diameter of the vesicle, a unimodal distribution of dense-cored vesicle cells was found in both control and hypoxic paraganglia. The vesicle diameter increased by about 19%, whereas the numerical density of dense-cored vesicles and the vesicle volume density were unaltered after hypoxia. Recurrent laryngeal nerves assayed by a sensitive high performance liquid chromatography technique contained an average of 1.9 pmol dopamine and 1.3 pmol norepinephrine. Exposure to 2 weeks of hypoxia increased the dopamine level to 4.9 pmol, whereas the norepinephrine content was unchanged. It is suggested from this study that the catecholamines determined are housed in the paraganglia of the recurrent laryngeal nerve.

Paraganglia of the superior laryngeal nerve of the rat

Paraganglia were consistently found at the bifurcation of the superior laryngeal nerve of the rat. Ultrastructurally the paraganglionic cells resembled the type I and type II cells of the carotid body. The dense-cored vesiculated type I cell was found most frequently, whereas the type II cell represented 10-25% of the cell population. The volume density of the dense-cored vesicles was found to be 3.5 +/- 0.5, which is about half as much as that found in the recurrent laryngeal nerve and about twice of that found in the carotid body. A total of 24,634 dense-cored vesicles were measured, and the mean diameter was calculated to be 113.8 +/- 4.9 nm. Based on the median vesicle profile diameter, only one type of dense-cored vesicle cell was found.

The recurrent laryngeal nerve in spastic dysphonia. A light and electron microscopic study

Sections of right or left recurrent laryngeal nerve (RLN), removed from patients with spastic dysphonia (SD) at the time of surgery, were studied using light and electron microscopy and were compared with control RLNs. In both groups, small, medium and large-sized myelinated nerve fibres were found in the RLN. Furthermore, numerous unmyelinated axons intermingled with the myelinated fibres were detected in the control group as well as in SD specimens. Slight morphometric differences were also found between the two groups, but these cannot explain the causation of spastic dysphonia.

Paraganglia of the human recurrent laryngeal nerve

Recurrent laryngeal nerves (RLNs) from human autopsy material were collected and prepared for light microscopy. Within five of eight investigated RLNs, paraganglia-like organs were found, the mean cross-sectional area of which was estimated to be 0.03 mm2. These organs were composed of cells resembling the type I and type II cells of the carotid body. The possible function of laryngeal nerve paraganglia is discussed.

Immunohistochemical and ultrastructural observations on adenoid cystic carcinoma of salivary glands. With special reference to intermediate filaments and proteoglycan particles

In adenoid cystic carcinoma (ACC) of salivary gland origin, intermediate filaments of tumour cells were investigated by immunohistochemical techniques and complex carbohydrates within the pseudocysts by ultrastructural methods. The intermediate filament proteins vimentin and cytokeratin were found in most neoplastic cells. The pseudocysts of the tumours were found to contain proteoglycan particles stainable after glutaraldehyde fixation--but not after osmium fixation alone. Ruthenium red (cationic dye) enhanced the staining whereas periodic acid-chromic acid-silver methenamine staining or phosphotungstic acid staining did not visualize the proteoglycan particles mainly containing acid proteoglycans which are normally produced by mesenchymal tissue. The cells of adenoid cystic carcinoma thus have an intermediate filament content and produce complex carbohydrates characteristic of both epithelial and mesenchymal tissue. Hence, an origin in an undifferentiated pluripotential cell seems plausible.

Catecholamines of endoneurial laryngeal paraganglia in the rat

The catecholamines in the recurrent and superior laryngeal nerves of the rat were assayed by high performance liquid chromatography. The nerves were shown to contain high levels of dopamine (1.9 +/- 0.6 and 2.3 +/- 0.4 pmol, respectively) and noradrenaline (1.3 +/- 0.3 and 0.9 +/- 0.2 pmol, respectively). No adrenaline could be detected in any of the nerves. Reserpine markedly depleted the stores of these amines in both nerves. A significant increase in dopamine level was seen in the superior laryngeal nerve after treatment with a monoaminoxidase inhibitor, but not in the recurrent laryngeal nerve. The high levels of dopamine detected are presumably derived from endoneurial paraganglia which were demonstrated by glyoxylic acid-induced fluorescence. The source of noradrenaline is less evident, but noradrenaline is probably stored in both endoneurial paraganglia and in sympathetic nerve endings.

Ultrastructural and immunohistochemical aspects of carcinoma in mixed tumors

Four cases of malignant mixed tumor (carcinoma in pleomorphic adenomas) were studied for ultrastructural appearance and for the presence of cytokeratins and vimentin. Ultrastructurally, both squamous and glandular epithelial differentiation were found not only in the same tumor but also within the same cell. One tumor showed mainly mesenchymal differentiation with fibroblast-like cells. The intermediate filament expression of benign mixed tumors (i.e., both cytokeratin and vimentin content) were found in two of the three malignant tumors investigated. In the third tumor, only cytokeratins were found. Thus, the filament content of mixed tumors may change when the tumor becomes malignant. This change does not always parallel a change in morphology. Although one tumor was clearly epithelial ultrastructurally and another mostly mesenchymal, both did contain both cytokeratins and vimentin.

Fine structure of the rat tympanic membrane after treatment with local anaesthetics

The tympanic membrane of the rat was studied ultrastructurally after application of a local anaesthetic--lidocaine spray. Already after 10 min, degenerative changes--or even necrosis--were observed on both epithelial surfaces of the eardrum. Later on, a marked hyperplasia of the epidermal layer was most characteristic, as was a proliferation of the fibroblasts of the subepithelial connective tissue. After 3 weeks the eardrum had not regained its normal appearance. No perforations were encountered and only minute substructural changes could be detected within the fibrous layer.

Fiber composition of the recurrent laryngeal nerve after experimental vagotomy and sympathectomy. A qualitative study by light and electron microscopy

A qualitative study of the nerve fiber composition of the recurrent laryngeal nerve of the rat was performed by light and electron microscopy. Various surgical denervation procedures were employed to determine the origin of the variously sized myelinated fibers and the unmyelinated axons present within the nerve. After extracranial vagotomy all myelinated fibers degenerated, whereas some unmyelinated axons remained intact. Intracranial vagotomy on the other hand revealed that about 70% of the small (1.5-4.0 micron) myelinated fibers were unaffected, as were many unmyelinated axons. After sympathectomy, both kinds degenerated but normal unmyelinated axons could be found. Thus, the majority of the small myelinated fibers are afferent sensory fibers whose cell bodies are located in the vagal ganglia at the base of the skull. The medium and large myelinated fibers represent efferent neurons originating from the brain stem. The unmyelinated fibers emanate from at least three different sites, viz. the brain stem, the sensory vagal ganglia and finally the ganglia of the cervical sympathetic nerve trunk.

Developmental influences of the sympathetic nervous system on rat parotid gland

In an attempt to evaluate the effect of the sympathetic nervous system on the postnatal maturation of the parotid gland, rats were either sympathetically denervated on one side by avulsion of the superior cervical ganglion within 4 h after birth or treated with various beta-adrenoceptor blocking agents from the day of birth. Four or 9 weeks later the animals were killed and the parotid glands were subjected to quantitative morphological studies. The neonatal denervation caused a significant decrease in parotid acinar cell size and their granule content, whereas chronic beta-adrenoceptor blockade was without any effect. It is suggested that the trophic effect of the sympathetic nervous system may be due to a growth factor released from sympathetic nerve endings, which does not seem to interact with the beta-adrenoceptor system.