Intraoperative microwave processing of bone margins during resection of head and neck cancer.

OBJECTIVE: To develop an accurate method for performing histopathologic analysis for a full cross-section of cortical bone within 2 to 3 hours. METHODS: Microwave technology was used to augment and to more rapidly perform fixation and decalcification of cortical bone. RESULTS: Using the methods described, slides suitable for histopathologic analyses regarding the presence or absence of malignant tumor were prepared in 2 to 3 hours and, in 10 patients studied, had a 100% correlation with slides prepared in 7 days using the standard decalcification technique. CONCLUSION: Microwave technology allows accurate assessment of a full cross-section of cortical bone regarding the presence or absence of malignant tumor within the time limits required for resection of a malignant head and neck tumor and reconstruction of the surgical defect.

Effects of meals and meal times on uptake of lead from the gastrointestinal tract in humans.

Twenty three adults ingested 203Pb as lead acetate on the 12th hour of a 19 h fast. Retention measured 7 days later in a whole-body counter was 61% and whole-body turnover rates suggested that initial uptake had been considerably greater. Balanced meals eaten with 203Pb reduced lead uptake to 4% and the influence of the food lasted for up to 3 h. The effects of phytate, ethylene-diaminetetra acetate (EDTA), caffeine, alcohol, glucose, a liquid meal and a light snack were tested separately with intermediate results. The effect of a meal was probably largely due to its content of calcium and phosphate salts but lead uptake was probably further reduced by phytate which is plentiful in whole cereals and it was probably increased by a factor in milk. Uptake with skimmed milk was the same as with whole milk and we suggested that the factor was not fat. Comestibles with low mineral and phytate contents reduced lead uptake by intermediate amounts, possibly by stimulation of digestive secretions. The avid uptake of lead during a fast, the large reduction of lead uptake with meals and the likelihood of variations in gastric-emptying rates and dietary habits may be major causes of variation in body burdens of lead in the population.

The transport of the lead cation across the intestinal membrane.

1. The transport of the lead cation has been investigated using the everted sac preparation of Wilson & Wiseman (1954).2. Only a small percentage of lead was transported into the serosal compartment but there was a rapid and massive uptake onto the tissue. There was no significant difference in the amount of lead cations transported across different regions of the small intestine.3. Both the rate of transport into the serosal compartment and the tissue uptake increased linearly with increasing concentration of the lead cation, from 10(-7)M to 5 x 10(-5)M. Little evidence for saturation of serosal transport or tissue uptake was found.4. Lead transport into the serosal compartment appeared to be related to water movement, but was little affected by changes in glucose concentration and temperature.5. It is concluded that lead is transported into the serosal space by a process of passive diffusion linked to water transport.6. The interaction between lead ions and the intestinal tissue was extremely tenacious and displayed characteristics of covalent bonding.7. It is suggested that the lead cation interacts with tissue phosphate ions thus removing lead ions from the transport pool. Chelation of lead to form a neutral species reduces this interaction and also promotes transport.

Intestinal surface acid microclimate in vitro and in vivo in the rat.

The presence of the intestinal surface acid microclimate (ISAM) has long been suggested. Controversy, however, still exists as to the existence, general characteristics, and requirements of this microclimate. We examined the existence and distribution of the ISAM along the rat small intestine and colon and determined its general characteristics. The results clearly demonstrate the existence of the ISAM in vitro and in vivo. Glucose and sodium in the incubation medium, as well as normal intracellular metabolism, are essential requirements for the formation and maintenance of the ISAM. We conclude that the ISAM is a normal physiologic phenomenon of the luminal surface of the intestine.