Electron microscopic and immunohistochemical investigation of Reinke's edema

Examination was made of the vocal fold mucosa of Reinke's edema immunohistochemically and electron microscopically, with special attention to blood vessels in Reinke's space (RS). Ten surgical specimens of Reinke's edema were used, and the results obtained are summarized as follows. There were subepithelial vascularization and many dilated vessels in RS. The vessels had thin endothelium with many fenestrae, many vesicles, and a thickened basement membrane. Plasma exuded from the capillaries into surrounding tissue via fenestrae. These findings demonstrate increased permeability of the vessels. The vascular walls were thin, with few pericytes. The pericytes were situated away from the endothelial cells. Some endothelial cells and pericytes had degenerated, and vessel occlusion was apparent in some cases. These findings indicate the vessels had become fragile. Interstitial cells and/or inflammatory cells in RS showed stained cytoplasm with vascular endothelial growth factor. This growth factor may possibly enhance capillary permeability and form fragile vessels in RS. Fragility and alteration in permeability of the vessels are presumed to cause edema of RS, which may progress to Reinke's edema.

Vocal cord basement membrane in non-sudden infant death syndrome cases

Vocal cord basement membrane thickening (VCBMT) has been observed in children with sudden infant death syndrome (SIDS). It has been proposed that this lesion could be used as a positive indicator of this syndrome in autopsies of children who have died unexpectedly. The present investigation aimed to analyze vocal cord basement membranes from autopsies of children 0 to 365 days old. A total of 134 larynges were analyzed. Histological sections of paraffin-embedded larynges stained with H&E and submitted to histochemical staining with periodic acid-Schiff (PAS), Masson's trichrome, syrius red, and Carstairs were used for light microscopy analysis. Immunohistochemistry with monoclonal anti-collagen IV antibody was used to determine the nature of VCBMT. The study was completed with morphometry of H&E- and PAS-stained sections and revision of the clinical information contained in the hospital files. VCBMT was found in 25 cases (18.7%) and showed characteristics of normal basement membrane, including immunoreactivity to collagen IV. Our data support the conclusions that VCBMT is frequently seen in pediatric autopsies, is seen in children in all age-groups studied whose deaths were due to causes other than SIDS, and is commonly associated with infectious diseases. Like SIDS, VCBMT occurs in the first year of life.

Reticular fibers in the vocal fold mucosa

Light and electron microscopic investigations of the reticular fibers (RFs) in the vocal fold mucosa were carried out on excised human adult larynges. The results are summarized as follows. Reticular fibers were found in the superficial and intermediate layers of the lamina propria of the vocal fold mucosa. They were most abundantly discovered around the vocal fold edge, and they decreased toward the superior and inferior portions of the vocal folds. The RFs were composed of slender fibrils, about 40 nm in diameter, and having cross-bands with a periodicity of about 67 nm. They were found in close association with the basal lamina of the epithelium and blood vessels. The slender fibrils of the RFs did not form any bundles, but branched and anastomosed. The RFs formed delicate 3-dimensional networks, and the spaces among the fibers were relatively large. Glycoprotein and glycosaminoglycan (proteoglycan) were situated around the RFs and in the spaces among the fibers. Elastic fibers were located in the spaces among the RFs. The 3-dimensional structure of the RFs in the vocal fold mucosa, first demonstrated in this study, appears to be one of the key components of the structural maintenance and viscoelasticity of the vibrating vocal fold tissue.

The histologic fate of autologous collagen injected into the canine vocal fold

Collagen is a functionally essential component of the five-layered structure of the vocal fold. Soluble bovine collagen has previously been shown to be an effective injectable bioimplant for vocal fold defects, paralysis, and, especially, scarred larynges. Although bovine collagen appears to be well tolerated, the concern for possible adverse immunologic responses has deterred approval from the Food and Drug Administration for its clinical use in the larynx. Currently we are investigating the use of injectable autologous collagen for vocal fold augmentation. The purpose of this study is to examine the histologic fate of autologous collagen injected into the canine vocal fold at multiple intervals after injection. An ellipse of skin measuring 3 x 6 cm was harvested from each of three dogs and processed into a naturally cross-linked injectable solution of collagen (Autologen). This autologous collagen was injected into one vocal fold and a control injection of buffer solution was injected contralaterally. The injections were well tolerated and no dog appeared to suffer any immediate or delayed ill effects. The dog larynges were harvested 1, 3, and 6 months after collagen injection and examined grossly and histologically. Injected autologous collagen material persisted in these experimental animals and appeared to be well tolerated. Based on this preliminary study, we anticipate autologous collagen to be at least as suitable as bovine chemically cross-linked collagen as an injectable bioimplant for vocal fold augmentation. It may also have the advantage of added safety and stability.

TGF-alpha immunoreactivity in laryngeal carcinoma: lack of prognostic value and correlation to EGF-receptor expression

BACKGROUND

Transforming growth factor alpha (TGF-alpha) is a polypeptide that is structurally similar to epidermal growth factor (EGF) that binds to the epidermal growth factor receptor (EGFR) and has been implicated in the development of several types of human tumours.

METHODS

The expression of TGF-alpha is examined in laryngeal squamous cell carcinoma (SCC) (n = 24) and non-neoplastic polyps (n = 7) using streptavidin-biotin immunohistochemistry and a monoclonal antibody to the TGF-alpha protein. These cases had been previously characterized for EGFR immunoreactivity. The carcinomas were classified as well differentiated (n = 2), moderately differentiated (n = 16) and poorly differentiated (n = 6). Tissues from metastatic tumour deposits in lymph nodes (n = 5) were also studied.

RESULTS

TGF-alpha overexpression was defined as intense immunoreactivity in more than two-thirds of tumour cells immunostained for TGF-alpha and was present in the majority of the SCC cases (n = 15; 63%) and metastatic tumour deposits (n = 4; 80%). In contrast, although some of the vocal cord polyps showed weak (n = 2) to moderate (n = 5) immunostaining, none had evidence of strong TGF-alpha immunoreactivity. The differences in TGF-alpha immunoreactivity were significant between primary laryngeal SCC and vocal cord polyps (P = 0.013; chi 2 test with continuity correction), and between metastatic laryngeal SCC and vocal cord polyps (P = 0.023; chi 2 test with continuity correction). There was no significant difference in TGF-alpha expression between the different grades of carcinomas (P = 0.92, chi 2 test) or between non-metastatic and metastatic carcinomas (P = 0.82; chi 2 test with continuity correction). No significant correlation was found between TGF-alpha expression and patient survival or tumour recurrence (r = 0.077, r2 = 0.006, P = 0.75; simple regression analysis), or between TGF-alpha expression and EGFR immunoreactivity (r = 0.325, r2 = 0.106, P = 0.0851).

CONCLUSIONS

In conclusion, increased TGF-alpha immunoreactivity is present in most cases of laryngeal SCC with no specific relationship to tumour grade, suggesting that it may be important in the development of laryngeal carcinomas but not in its progression. No significant correlation was found between TGF-alpha and EGFR expression in laryngeal tumours and TGF-alpha immunoreactivity is of no prognostic value.

PCNA--a cell proliferation marker in vocal cord cancer. Part II: Recurrence in malignant laryngeal lesions

Laryngeal squamous cell carcinoma constitutes the most frequent carcinoma found in the head and neck region. A precise prediction for recurrence potential cannot be done on site, treatment and histologic grading. Since Proliferating Cell Nuclear Antigen (PCNA) and DNA-cytometry have shown a good correlation between premalignant lesions and their progressive potential towards full-fledged carcinoma in the larynx as described in part I of this work, we have analyzed the PCNA index and DNA cytometry in specimen taken from vocal chord carcinomas with a 5-year follow-up, in order to assess its relationship with the presence or absence of tumour progression. 42 cases with (21) and without (2) recurrence have been examined. The DNA-index ranged from 1.01 to 1.43 (mean 1.10) in the group without and from 1.02 to 1.59 (mean 1.38) in the group with recurrent carcinoma (p = 0.002). The PCNA-index ranged from 0.00% to 18.90% (mean 6.97%) in the nonrecurrent group and from 0.00 to 3g.50% (mean 16.35%) in the patients with recurrence (p = 0.001). Both indices also correlated in a highly significant way. From these data emerges a highly significant correlation between the cytometric indices of cell proliferation and PCNA immunostaining. Furthermore the high correction between PCNA and DNA-index is of special interest for single case assessment. High DNA aberration and PCNA-index in vocal chord carcinoma may indicate a higher cellular aggressiveness of the tumour, resulting in a greater overall risk of metastases and local recurrences. Our results support the thesis that the indices of cellular proliferation within some cancers can define subsets of patients of high risk and help in isolating a population in which a more aggressive clinical protocol may be proposed.

Immunocytochemical study of proteoglycans in vocal folds

We evaluated the proteoglycan composition of normal vocal folds using immunocytochemical techniques. Frozen sections of 14 normal cadaveric vocal folds were obtained within 12 hours of death and sectioned immediately. Vocal fold sections were stained with antibodies against keratan sulfate, chondroitin sulfate, heparan sulfate proteoglycan (HSPG), decorin, and hyaluronate receptor. We found that the lamina propria has diffuse staining of fibrillar components with keratan sulfate and decorin. Intense staining was observed in the vocal ligament area with keratan sulfate. The HSPG was localized to be basement membrane zone. Chondroitin sulfate, HSPG, and hyaluronate receptor were detected in the cytoplasm of interstitial cells with immunocytochemical characteristics of macrophages. The keratan sulfate distribution suggests that fibromodulin may be significant in normal vocal folds. Production of HSPG and probably versican occurs in macrophages and fibroblasts in the lamina propria.

Age-related changes of the macula flava of the human vocal fold

This investigation was carried out to determine the histologic structure and age-related changes of the macula flava of human aged vocal folds. Excised human adult senescent larynges served as the material for this study. Light microscopic and transmission electron microscopic observations were made. The results are summarized as follows. 1) The anterior and posterior maculae flavae were elliptical in shape and about 1.5 x 1.5 x 1 mm in size. 2) The macula flava was composed of fibroblasts, elastic fibers, collagenous fibers, and ground substance. 3) The number of fibroblasts decreased. 4) Components in the cytoplasm, such as Golgi apparatus and rough endoplasmic reticulum, were fewer than in younger adults. 5) Some fibroblasts and some components in the cytoplasm degenerated. 6) The accumulation of glycogen granules and lipid droplets were seen in the cytoplasm. 7) The number of collagenous and elastic fibers synthesized by the fibroblasts decreased. 8) These findings were evident to various degrees and suggested the reduction of fibroblast activation, abnormal metabolism, and degeneration. A decrease in the number and activation of fibroblasts in maculae flavae indicates decreased synthesis of fibrous components in the vocal fold mucosa. This in turn influences the viscoelasticity and stiffness of vibrating tissue and contributes partially to aging of the voice.

A tissue-culture model for the study of canine vocal fold fibroblasts

A tissue-culture model has been developed for the study of fibroblasts from the canine vocal fold. Laryngeal tissue (lamina propria) obtained from euthanized dogs is rinsed, cut into 1-mm3 pieces, and incubated in 5% carbon dioxide at 37 degrees C. A confluent monolayer is established within several days. Detectable levels of elastin in the tissue culture supernatant are measured by an indirect enzyme-linked immunosorbent assay. Various external agents have been shown to affect elastin production. The effects of KTP laser irradiation, hydrocortisone (1.3 mumol/L), transforming growth factor-beta (10 ng/mL), and human leukocyte elastase have been measured. Thus the canine vocal fold fibroblast tissue culture is established as a model for further investigations to improve wound healing and to understand the wound-healing process following laryngeal microsurgery.

Benign pathologic responses of the larynx

Benign laryngeal lesions were examined for patterns of injury indicated by deposition of fibronectin and collagen type IV. An immunoperoxidase technique was used to compare 33 fresh or paraffin-embedded tissues with regard to their staining of monoclonal antibodies directed against fibronectin and collagen type IV. Two types of patterns were recognized. One pattern showed intense fibronectin deposition in the superficial layer of the lamina propria, often coupled with basement membrane zone injury, indicated by thick collagen type IV bands. The other pattern showed rare basement membrane zone injury and very little fibronectin deposition. The first pattern correlated more with nodules, the second pattern more with Reinke's edema and some polyps. A better understanding of the effects of excessive deposition of structural glycoproteins such as fibronectin and of abnormal proteoglycan deposition may lead to a better characterization of vocal fold disease and its causation and, ultimately, better treatment.

Morphology of the basement membrane

The aim of this contribution is to summarize our knowledge of the morphology of the basement membrane (BM). The first step in this direction is the attempt to define this term. The BM is composed of the Lamina lucida, densa, and fibroreticularis. Subsequently, the historical development of this term is discussed. Our main interest is, of course, focused on the description of the BM-structure up to the macromolecular level and the special forms of this structure. This is supplemented by discussing its chemical composition and establishing a relationship between morphology and biochemistry. The obtained findings yielded some indications as to the molecular composition of the BM which may serve for the construction of "models." The composition of the Lamina lucida (L.l.) and the Lamina or Pars fibroreticularis (L.f.) must be discussed separately, since, if present, they show a different and strongly varying structure (L.f.). An important aspect is the function of this extracellular layer which comprises mechanical tasks up to inductive effects. Finally, the concepts of the formation of the BM, especially of the Lamina densa (L.d.), are summarized. It obviously consists of a sequence of individual steps which starts with expression and secretion of the L.d.-components and is followed by an induction of integrin expression.

Group-selective reagent modification of the sodium- and chloride-coupled glycine transporter under native and reconstituted conditions

Glycine transporter from rat brain stem and spinal cord is inactivated by specific sulfhydryl reagents. Modification of lysine residues also promotes a decrease of the transporter activity but in a lesser extent than that promoted by thiol group reagents. Mercurials showed a more marked inhibitory effect than maleimide derivatives. SH groups display a similar reactivity for p-chloromercuribenzenesulfonate (pCMBS) and mersalyl in synaptosomal membrane vesicles and proteoliposomes reconstituted with the solubilized transporter. However, different reactivity is observed with N-ethylmaleimide (MalNEt), the greatest effect being attained in membrane vesicles. The rate of inactivation by pCMBS and MalNEt is pseudo-first-order showing time- and concentration-dependence. pCMBS and MalNEt decrease the Vmax for glycine transport and to a lesser extent act on the apparent Km. Treatment with dithiothreitol (DTT) of the transporter modified by pCMBS results in a complete restoration of transporter activity indicating that the effect exercised by the reagent is specific for cysteine residues on the protein. It is concluded that SH groups are involved in the glycine transporter function and that these critical residues are mostly located in a relatively hydrophilic environment of the protein.

Lidocaine absorption and metabolism after oropharyngeal application in young and young-elderly adults

The purpose of this study was to evaluate the effect of age on lidocaine absorption and metabolism after application to the oropharynx and vocal cords in a manner similar to preparation for flexible fiberoptic bronchoscopy. Five healthy volunteers were studied in each of two age groups: from 25 to 37 and 60 to 68 years of age. Each volunteer had a total of lidocaine 300 mg administered as a gargle, gel, or directly to the vocal cords. Blood samples and expectorant were collected to determine concentrations of lidocaine and its metabolites, monoethylglycinxylidide (MEGX) and glycinxylidide (GX). No differences in peak plasma lidocaine concentrations, 2.09 +/- 1.28 mumol/L (1 microgram/mL = 4.27 mumol/L) in young subjects, and 2.35 +/- 0.85 mumol/L in young-elderly subjects, or lidocaine AUC were seen between the two age groups. Lidocaine recovered in expectorant ranged from 96 to 168 mg. This study suggests that, over the age range studied, increased age does not impair lidocaine absorption from the oropharynx or lidocaine metabolism when topical lidocaine is used during flexible fiberoptic bronchoscopy.

Measurements of oxygen pressure in the vocal fold during laryngeal nerve stimulation

To clarify the mechanisms of ischemic change in the vocal fold on phonation, model experiments were performed under various conditions by recording tissue oxygen pressure (Pto2) values under electrical stimulation of either the recurrent laryngeal nerves or external branches of the superior laryngeal nerves. In addition, autonomic nerve regulation of laryngeal vessels was estimated under administration of succinylcholine chloride. Oxygen pressures of the vocal fold were measured in the lamina propria and vocal muscle at the middle of the membranous portion. The Pto2 in the lamina propria showed a slight increase during lower-frequency stimulation and a slight decrease during higher-frequency stimulation of the recurrent laryngeal nerve. The Pto2 in the vocal muscle showed a decrease during stimulation of the recurrent laryngeal nerve. On the other hand, the Pto2 showed almost no change in the lamina propria or vocal muscle during stimulation of the external branch of the superior laryngeal nerve. It is supposed that an ischemic change in the vocal muscle on phonation results mainly from contraction of the vocal muscle. On the contrary, the ischemic change in the vocal mucosa on phonation does not appear to be directly caused by the contraction of the vocal muscle but by other factors, such as wavelike movement.

Histologic studies on the fate of soluble collagen injected into canine vocal folds

Collagen is an essential component of the functionally important layered structure of the vocal cord. Soluble bovine collagen appears to be suitable for injection into vocal folds to correct glottic insufficiency. Clinical trials and preliminary laboratory studies with the canine larynx indicate that injectable collagen is safe, effective, easily injected, and well-tolerated. Bovine collagen softens scar tissue, attracts the ingrowth of host fibroblasts, and allows the eventual replacement of the implant by new host collagen. This study examines the fate of collagen injected into canine vocal folds. Two forms of soluble bovine collagen, differing only in the amount of chemically induced cross-linkage, were injected into vocal folds of dogs; the animals were then killed at 12-week intervals for 1 year. Gross and histologic examination showed that both substances tended to be resorbed when injected deeply in the vocalis muscle, but persisted when injected in the plane of the vocal ligament - a site normally composed of dense collagen. The invasion of the implant by active host fibroblasts and the secondary deposition of new host collagen were evident in histologic sections. Examination with polarized light confirmed the presence of birefringence characterizing host collagen. The invasion of fibroblasts and deposition of new collagen in the implant were seen with electron microscopy. Cellular invasion seemed to progress more rapidly in the cross-linked preparation. Injected collagen did not evoke a foreign body reaction in any specimen studied, and was well-tolerated during replacement by host tissue.

Autoradiographic evidence of sex steroid receptors in laryngeal tissues of the baboon (Papio cynocephalus)

A number of studies have implicated the gonadal steroids as significant factors in laryngeal development and disease. In addition, antiandrogens are receiving limited trials in the treatment of laryngeal carcinoma. However, there is little experimental data to document the presence, and more specifically the location of receptors for the sex steroid hormones in the larynx. The purpose of this study is to provide such data. Utilizing an autoradiographic technique, tissues from baboons injected with tritiated estradiol (3H-E2) or dihydrotestosterone testosterone (3H-DHT) were examined and analyzed. The data gathered confirmed that the larynx is rich in receptors for these steroids and that there are specific patterns of distribution of receptor positive cells. The vocalis muscle and other mesenchymal tissues contained the largest number of receptors, while ciliated columnar and stratified squamous epithelium were negative. The significance of these findings is discussed.

A histochemical study of simple laryngeal polyps

Benign laryngeal polyps and normal larynxes have been studied by histochemical and other staining methods. These show that the polyps contain much free hyaluronic acid and 6-chondroitin sulphate. Their mode of production may be the mechanical separation of these compounds from collagen fibres by vibration. An alcian-elastic stain may be a helpful diagnostic method.

Estrogen target cells in the larynx: autoradiographic studies with 3H-diethylstilbestrol in fetal mice

Serial sections from 16-day mouse embryos from mothers injected with 3H-diethylstilbestrol were processed for autoradiography. The distribution, in the laryngeal region, of cells with nuclear concentrations of radioactivity was analyzed. Estrogen receptor cells were found in the mesenchyme of the vocal cords and lateral to the laryngeal aditus. The embryological and oncological implications of these findings are discussed.