We investigated the expression of vascular endothelial growth factor (VEGF) and microvascular density in 54 cases of invasive laryngeal squamous cell carcinoma (SCC) and in ten samples of normal laryngeal tissue using immunohistochemistry methods. The study also focused on the distribution of mast cells in and around the SCCs. The microvascular density in laryngeal carcinoma tissue was higher than that in normal tissue (P = 0.02). VEGF was localized in SCCs, stromal cells, endothelial cells, minor salivary glands, and non-cancer epithelium adjacent to the tumor. VEGF expression in the tumor cells was found in 13 of 54 cases (24.1%), whereas mast cells around the carcinomas were VEGF positive in all 54 cases. Staining of VEGF in SCCs was strong in the area of high microvascular density (P = 0.0002). Using a multi-labeling subtraction immunostaining method, VEGF-positive stromal cells were classified mostly as mast cells and, in a few instances, as macrophages. VEGF staining in SCCs was associated with the mast cell count (P = 0.0001). There was no distinct correlation between VEGF expression and pTNM stage of an SCC. In conclusion, the results suggest that VEGF might be an important angiogenic factor in cancer invasion. Laryngeal cancer cells and mast cells may control the angiogenic response by releasing VEGF.

Swallowing-related neurons (SRNs) were recorded systematically in the medulla oblongata of urethane-anesthetized cats. The SRNs received orthodromic inputs from the superior laryngeal nerve (SLN) and showed transient changes in their activity synchronous with swallowing. These neurons could be divided into three types. Type I SRNs are sensory-relay neurons from the SLN in the nucleus of the tractus solitarius (NTS), type II are interneurons located diffusely in the parvocellular reticular formation ventral to the NTS, which received oligosynaptic inputs from the SLN, and type III are motoneurons in the nucleus ambiguus. Some type II neurons still showed the swallowing activity after the animals were paralysed, which suggests that they could be involved in the generation of swallowing outputs.

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We studied three patients: two with voice and hand tremor, and one with voice tremor. Voice tremor was associated with synchronous rhythmic contraction of cricothyroid and rectus abdominis muscles, but not always vocalis muscle. Voice tremor was manifested only in voluntary phonation or expiration, not in involuntary phonation, voluntary inspiration, or involuntary expiration and inspiration (breathing at rest). Impaired regulation of the CNS programs innervating the voluntary expiratory muscles probably causes voice tremor. Clonazepam and propranolol were helpful in blinded studies.

Expression of c-Met, a gene for the hepatocyte growth factor/scatter factor (HGF/SF) receptor, is known to be associated with tumour development in several human carcinomas. The expression of c-Met was examined using immunohistochemistry in 82 cases of primary laryngeal carcinoma to evaluate the tissue distribution of c-Met and the clinicopathological significance of c-Met expression. In normal larynx, c-Met expression was observed only in some minor salivary glands. Positive reaction for c-Met in neoplastic epithelium was noted in 45 out of 82 (54.9%) cases. In 44 cases, structures adjacent to the carcinoma (noncancerous squamous epithelium, some stromal fibroblastic cells, and endothelial cells) showed positive reaction for c-Met. c-Met expression in cancerous epithelium was significantly correlated with lymph node status (P<0.04) and proliferating activity expressed by the Ki-67 labelling index (P<0.02). There was no correlation between c-Met expression and age, sex, histological type, T category, distant metastasis or clinical stage. The data suggest that overexpression of c-Met in laryngeal carcinomas represents a growth advantage for cancer cells, which may be conferred by the mitogenic effect of HGF/SF. Simultaneous c-Met expression in noncancerous components of the larynx may represent a paracrine modification of c-Met.

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To study the mechanism of autonomic regulation in the larynx, intralaryngeal local ganglia of the cat were investigated using immunohistochemical techniques. Small intralaryngeal ganglia were found in the peripheral portions of internal branches of the superior laryngeal nerve. Ninety-one percent of the ganglionic neurons were immunoreactive (IR) to vasoactive intestinal polypeptide (VIP), and 10% of the VIP-IR cells were also immunoreactive to enkephalin (ENK) and/or substance P (SP). The immunoreactivity of neuronal cell bodies remained unchanged even after denervation of the bilateral superior and recurrent laryngeal nerves. A dense distribution of calcitonin gene-related peptide (CGRP)-IR nerve fibers was found around almost all neuronal cells in the intralaryngeal ganglia. A few VIP-IR, ENK-IR, and SP-IR nerve fibers were also observed. Only the CGRP-IR fibers disappeared after the denervation experiments. In the laryngeal glands and mucosal arterioles, VIP-IR nerve terminals were found that were also immunoreactive to ENK and/or SP. However, these immunoreactive nerve endings in the glands and arterioles remained after the denervation experiments. The results of our study indicate that laryngeal exocrine secretion and blood flow are regulated by postganglionic autonomic parasympathetic fibers from intralaryngeal ganglia that contain VIP alone or VIP with ENK and/or SP, and that these ganglionic neurons may be innervated by CGRP-IR extrinsic nerve fibers.