The presence of microtomy induced distortion in paraffin sections is a significant hindrance to the accurate alignment of sections for three‐dimensional reconstructive techniques. Measurement of section distortion in various rat tissues demonstrated distortions to be present in all sections, with over 85% of such distortions being manifest as expansions when compared to the original distances between a series of eight drilled fiducial marks. Mean percentage dimensional changes in the direction of the cutting stroke and at right angles to this direction were ‐0.5 ± 1.5% and 3.7 ± 1.2% for liver, 7.6 ± 2.4% and 9.1 ± 1.2% for kidney, 6.6 ± 2.3% and 10.5 ± 1.4% for lung, and 20.3 ± 6.6% and 8.9 ± 5.9% for skeletal muscle. Individual sections invariably displayed measurable distortions, with only skeletal muscle showing any consistent pattern, in the form of “barrel” distortion at right angles to the cutting stroke. In addition a method of distortion correction and simultaneous image alignment is presented as a means of section alignment with full distortion correction capability. This method uses a quadratic polynomial transform in a non‐linear “unwarping” algorithm, to correct for the rotational and translational misalignment as well as for microtomy and camera aspect ratio distortions. Application of this method to a sequence of 46 serial sections demonstrated an alignment accuracy to within 2.6 ± 0.8 pixels. © 1994 Wiley‐Liss, Inc.

The present study involves an immunohistochemical analysis of p53 protein expression in head and neck tumours located at two separate subsites, the larynx and hypopharynx. It attempts to relate differences in expression to differences in the behaviour of these tumours. Detection of the p53 protein was performed using immunohistochemistry on 32 specimens of hypopharyngeal squamous cell carcinoma and 35 specimens of laryngeal squamous cell carcinoma. p53 overexpression was found in 66% of the hypopharyngeal tumours and in 51% of the laryngeal specimens analysed. Some differences between the two tumour types were noted in the pattern staining. p53 staining in those with hypopharyngeal tumours was associated with a statistically significant increased survival. For laryngeal carcinoma the converse was true but did not reach statistical significance. Differences in the behaviour of different head and neck tumour types may be reflected in differences in expression of the p53 protein. While p53 protein expression does not appear to be a useful prognostic indicator in laryngeal carcinoma it might be a useful prognostic indicator in tumours of the hypopharynx. Moreover, it may help predict those tumours which are radioresistant, thus suggesting other modes of treatment for these tumours. Of particular importance is the molecular basis for the observed differences in survival associated with p53 expression in the two tumour sites. This is under further investigation.

Adenosine, guanosine, inosine, cytidine, and uridine have been oxidised with periodate to give the respective asubstituted derivatives of a'-hydroxymethyloxydiacetaldehyde (' ribonucleoside dialdehydes '). These have been isolated by a simple procedure which involves extraction with ethanol, thus separating the dialdehydes from inorganic material. The compounds so isolated are more stable than has been suggested by early work in this field. 1.r. and n.m.r. spectroscopy show that the compounds contain few if any free aldehyde groups. They appear to be mixtures of hydrated forms although they run as single spots on t.1.c. in several solvent systems. Dried samples also contain virtually no aldehyde groups, and the possibility that they are polymeric structures as suggested by others, is discussed. With the exception of ' guanosine dialdehyde,' the amplitude of the Cotton effect in the 0.r.d. spectrum is less than that in the parent ribonucleoside.OXIDATION of ribonucleosides with periodate gives a-importance in establishing the structure of the natural substituted derivatives of a'-hydroxymethyloxydiacet-ribonucle~sides.~-~ Later it was shown that periodate aldehyde (I) (' ribonucleoside dialdehydes '). The initial oxidation of the terminal nucleoside of a ribonucleic acid interest in these compounds arose because of their followed by elimination of this residue under basic conditions provides a method for stepwise degradation of

We present 70 patients with tumours of the posterior pharyngeal wall, considering tumours of the posterior hypopharyngeal and posterior oropharyngeal wall as one unit. Almost half (45%) of the patients were in poor general condition at the time of presentation, and 60% had Stage III or IV tumours. One‐third of the patients were untreated, and surgery was mainly reserved for patients with Stage I and II tumours. The larynx could be preserved in two‐thirds of those undergoing surgery. The best current method of repair of the posterior pharyngeal wall after partial pharyngectomy appears to be a revascularized radial forearm flap. The median survival for patients with Stage I tumours was 236 weeks, but for patients with Stages II‐IV tumours was only 33 weeks. There was no significant difference between the survival for II–IV stage groups, but there was between Group I and the rest. We identify 2 defects in the UICC classification system: lack of definition of the lateral limit of the posterior pharyngeal wall, and a gross discrepancy between size and T staging of tumours arising primarily from the posterior wall of the hypopharynx.