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A comparison of primary suturing and a new laser weld technique is described for the microsurgical repair of the inferior alveolar nerve in Wistar rats. A reliable method of exposure of the inferior alveolar nerve has been developed in order to allow intraosseous repairs of the nerve involving suturing with 10:0 nylon and a laser weld technique using an albumin-based solder, containing indocynine cardiogreen, plus an infrared (810 nm wavelength) diode laser. Seven cases of microsuture and laser weld repairs were performed with a 29.4% reduction in total operating time in the laser weld group. Histochemical analysis showed comparable mean neuron counts and mean tracer uptake by neurons for the microsuture and laser weld groups. Giant cell reactions were identified in two of the primary suture cases and axon deflection in three cases demonstrating possible advantages of the laser weld technique which showed no adverse reactions by axons or epineurium to the coagulative repair with the solder. The technique of laser weld repair, on inititial analysis, therefore appears comparable with traditional suture repairs and indeed may possess several advantages. Further studies are recommended.

Metastatic spread to cervical lymph nodes is a major determinant of outcome in head and neck cancer. One hundred and ninety-six lymph nodes dissected from fresh surgical specimens from 24 patients with primary head and neck squamous cell carcinoma (SCC) were bisected. Messenger RNA (mRNA) extracted from one half and from a segment of the primary tumour was amplified by reverse transcriptase (RT)--polymerase chain reaction (PCR) with primers flanking the fifth intron of human type II keratin K5. DNA bands resolved by agarose gel electrophoresis were confirmed as specific transcripts by sequencing. The other half of each node was fixed in formalin for histology and, in selected nodes, for immunohistology for cytokeratins. Of 153 nodes suitable for analysis, 14 nodes contained metastatic tumour detected by light microscopy and also tested positive for K5 mRNA by RT--PCR. Fifty-six nodes were histologically negative for tumour but positive for K5 mRNA, and 83 nodes were negative for both histology and K5 mRNA. Extracts of the primary tumour always reacted positively for K5 by RT--PCR, whereas lymph nodes from patients without malignancies, and blood lymphocytes from a healthy volunteer reacted negatively. RT--PCR designed to detect the presence of processed transcripts of type II keratin K5 in stratified squamous epithelial cells may be a sensitive technique to detect the presence of viable and potentially metastatic carcinoma cells in lymph nodes draining head and neck SCC.

This note investigates the behaviour of the function h(θ) used in Wald's approximation to the operating characteristic function of a sequential probability ratio test for testing a parameter in an exponential family density.