Nasal endoscopy as a means of examining soft palate function

This paper reviews the visual methods available for the examination of the velopharyngeal portal in function. The various forms of nasal endoscope are differentiated together with the advantages and limitations of display and recording systems. Basic endoscopic technique is described.     

A study of the viscosity of saliva at different shear rates in dentate and edentulous patients

A Wells-Brookfield microviscometer was used to measure the viscosity of saliva from dentate and edentulous individuals at shear rates ranging from 1·15/s to 230/s. The advantages of using such an instrument are discussed in the light of the recognition of saliva as a viscoelastic fluid exhibiting non-Newtonian viscosity. The viscosity of saliva of the dentate group was found to be significantly higher than that of the edentulous group at shear rates above 1l·5/s. It is suggested that these differences may be related to the mucin content of saliva.     

The role of xeroradiography in cephalometric radiology.

The advantages of xeroradiography in the precise identification of anatomical landmarks for orthodontic analysis are overwhelming. In addition, the soft tissues of the face are shown fully and in detail. The tongue and soft palate can also be visualized. However, there is undue anxiety among clinicians and radiologists about the risk of excessive radiation exposure to patients. This has hitherto been regarded as unavoidable for the purposes of xeroradiography.This paper sets out in detail the advantages of xeroradiography for cephalometry and also clarifies the problem of patient exposure by presenting detailed measurements of the parameters affecting exposure and of the incident skin exposure. In this way it can be shown that by choice of correct kilovoltage and adequate filtration the incident skin exposure can actually be reduced when compared with conventional techniques using film.     

Cholinergic nerves of unknown origin in the parotid glands of rats.

The effectiveness of the parasympathetic denervation of the gland caused by avulsion of the auriculo-temporal nerve was investigated. In the first type of experiment, the cholinesterase inhibitor, eserine, was injected through the salivary duct. The substance is thought to preserve acetylcholine leaking from nerve endings, thereby causing secretion of saliva; a secretory response was thus taken as evidence for the presence of cholinergic nerves. In the second type of experiment, the acetylcholinesterase activity of the gland was examined histochemically. From the denervated glands, eserine caused secretion and acetylcholinesterase positive nerves were found in the glands. Both the amount of secretion and the number of nerves were greatly diminished when compared with the intact glands. The results indicate that the denervation procedure was incomplete, leaving some cholinergic nerves unsevered. That cholinergic nerves remain offers an explanation to the residual choline acetyltransferase activity, which has earlier been shown in the gland after avulsion of the auriculo-temporal nerve. To extend the denervation procedure, either avulsion of the facial nerve or avulsion of the superior cervical ganglion was included. Neither procedure abolished the response to eserine or the acetyl-cholinesterase activity, indicating that the routes for the remaining nerves are to be found elsewhere.     

The histologic evaluation of teeth transplanted between weakly disparate, genetically defimed mice.

Teeth transplanted between inbred lines of mice that differ by strong histocompatibility barriers are promptly rejected. However, when only one weak antigen difference exists between donor and recipient, teeth are known tp survive indefinitely. The purpose of this study was to determine if the histocompatibility barrier could be increased to two weak antigens without inducing a rejection episode. Allografted teeth was examined from 30 to 210 days after transplantation and, contrary to expectations, the teeth were rejected at about 60 days. Thus, all but the weakest of histocompatibility barriers are sufficient to cause the rejection of tooth allotransplants in mice.