Electron microscopic demonstration of viral particles in sudden infant death syndrome

Immunolocalization of prealbumin: distribution in normal human tissue

Using an indirect immunoperoxidase staining technique we have demonstrated the plasma protein, prealbumin, in the cells of the pancreatic islets of Langerhans. Serial sections stained with antisera to glucagon, insulin and somatostatin revealed that the distribution of the prealbumin stained cells matched that of the glucagon A-cells. Absorption and cross-absorption experiments with prealbumin and glucagon showed that the staining was specific. We also found positive staining for prealbumin in single cells in the mucosa of the gastrointestinal tract, mainly stomach and colon, and kidney tubules.

Sites of prealbumin production in the human fetus using the indirect immunoperoxidase technique

An indirect immunoperoxidase technique was used to investigate the site of prealbumin synthesis in the human fetus from between 8 and 43 weeks. Prealbumin staining was noted in the A cells of the fetal pancreas, both in the primary and secondary generations of the islets of Langerhans, from as early as 12 weeks gestation. Electron microscopy localized the staining to the cytoplasmic secretory granules. Prealbumin was also present in the gastrointestinal mucosa in cells which had a distribution similar to that of argentaffin cells. Positive staining was noted in the lining epithelium of the renal proximal convoluted tubules, but ultrastructural studies indicated that this was probably related to reabsorption, and not to synthesis.

Immunolocalization of prealbumin as a marker for carcinoid tumours

Using a PAP immunoperoxidase technique, we have demonstrated the plasma protein prealbumin in 92 (87 per cent) out of a series of 106 carcinoid tumours from various sites. The frequency of detection was greater than with the conventional stains; 83 (78 per cent) of the cases were positive for one or more of these stains. The Grimelius technique was by far the most effective of the conventional stains; it was positive in 81 (76 per cent) cases. We were unable to detect prealbumin in a variety of carcinomas. Although prealbumin identification did not appear to have any advantage over the routine stains in midgut-derived carcinoids, it was much more effective in the diagnosis of bronchial (foregut) and rectal (hindgut) carcinoids. We believe that prealbumin staining offers a cheap, reliable and valuable method for the detection of carcinoid tumours in routine histopathology.

Pepsinogen in gastric carcinoma cells

Immunoperoxidase staining of 125 gastric carcinomas showed pepsinogen in tumour cells of seven (5.6%) cases. Carcinomas from other sites were negative. The phenomenon is probably too uncommon to be useful in identifying secondary carcinomas as gastric in origin, but it is of some biological interest.