The material of 562 surgically removed renal cell carcinomas or adenomas was reviewed, and 18 tumors were diagnosed as renal oncocytomas. The incidence seemed to increase strikingly during recent years. Similarly, among 112 renal cell tumours from 8489 autopsies, 12 oncocytomas were found. Immunoperoxidase staining for alpha-I-antichymotrypsin was positive in all the tumours studied speaking for the origin from proximal tubular cells. All the tumours behaved in a benign fashion despite the large size and/or moderate histological atypia. The recognition of renal oncocytoma is urged, because its incidence seems to be increasing, and the prognosis is much better than that of renal cell carcinoma.

The relationship between myocardial ATP content and the increase in left ventricular resting tension during ischaemia (ischaemic contracture) was studied in isolated rat hearts perfused for 15 min either with aerobic buffer (pO2 greater than 500 mmHg) containing non-glycolytic substrate, acetate (5 mmol X litre-1), or with hypoxic buffer (pO2 less than 10 mmHg) with glucose (10 mmol X litre-1) before making them totally ischaemic for 10 min. ATP was determined spectrophotometrically from extracts of frozen whole hearts. Left ventricular tension was recorded by intraventricular balloon catheter. Myocardial ATP content was 15.4 +/- 1.0 mumol X g-1 dry weight (mumol X g-1) after 10 min stabilising period, 14.1 +/- 0.9 mumol X g-1 after 15 min aerobic perfusion (plus acetate) and 9.0 +/- 1.3 mumol X g-1 after 15 min hypoxic perfusion (plus glucose). During 10 min of ischaemia ATP decreased in aerobic hearts to 5.4 +/- 1.1 mumol X g-1 and to 7.9 +/- 1.0 mumol X g-1 in hypoxic hearts. The left ventricular resting tension increased during ischaemia in hypoxic hearts to 9 +/- 5% of control systolic pressure (0 = diastolic pressure, 100 = systolic pressure during stabilising period), whereas in aerobic hearts the tension began to increase immediately and was 84 +/- 22% of systolic pressure at the end of the ischaemic period. In parallel control experiments, hearts were also perfused either with glucose-containing aerobic buffer or acetate-containing hypoxic buffer. ATP was well preserved during aerobic perfusion (plus glucose) but decreased markedly during hypoxic perfusion (plus acetate). There was no increase in resting tension in the aerobic hearts (plus glucose) whereas the resting tension increased considerably during hypoxic perfusion (plus acetate). The results indicate that the initiation of ischaemic contracture occurs at much higher myocardial ATP level when ATP comes from mitochondrial sources than when ATP is generated by anaerobic glycolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

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A histochemical method for demonstrating lactate dehydrogenase activity was used in addition to standard Van Gieson stain to study early alterations near wounds made in pig skin by steel scalpel, electrocautery, two modes of CO2 laser (the rapid super-pulse mode and the continuous wave mode), and contact Nd:YAG laser. The enzyme-free zone near the wounds made using the thermal knives appeared to be twice as wide as the necrotic zone observed with Van Gieson stain. In polarized light, the enzyme-free area showed two zones of equal width with respect to birefringence of collagen fibers. The zone lacking birefringence correlated well with that observed with Van Gieson stain. The birefringent zone represented functionally damaged tissue with more or less normal structures by light microscopy. The damage to adjacent tissue caused with the thermal knives seems to be considerably larger than has usually been reported.

The effectiveness of two different techniques of laser-induced hyperthermia was analyzed in healthy piglet livers. Hyperthermia was produced using a continuous-wave Nd:YAG laser with both a contact sapphire probe and a bare quartz fibre. In both methods the tip was inserted into the liver, and the temperature 1 cm from the tip was raised and held between 42 degrees C and 44 degrees C for 600 seconds. Specimens were taken 0, 7 and 14 days after the treatment. The tissue effects of 36 treatment sites were analysed using standard van Gieson's method. In addition, a histochemical method for demonstrating lactate dehydrogenase activity was employed to show damage not observable by routine methods. No statistically significant difference in the extent of the treatment sites at d 0 and after 7 days was seen when comparing the two laser methods. After 2 weeks, the diameter of the lesion with the bare fibre was significantly larger (3,7 mm with both analysing methods) than by using the contact probe (2,6 with LDH demonstration; P < 0.01 and 2.1 mm with van Gieson's staining; P < 0.001). It can be concluded that the simple fibre tip seems more effective in causing tissue necrosis than the sapphire tip.