Histological and ultrastructural study of the effect of chemotherapy with 5-fluorouracil on normal liver of Wistar rats.

BACKGROUND: In this study, we analysed the histopathological and ultrastructural effects of systemic chemotherapy with 5-fluorouracil (5-FU) on the liver of healthy rats. METHODS: Twenty inbred Wistar rats were used as controls and another 20 rats received a bolus infusion, via the inferior vena cava, of 375 mg/m(2) 5-FU. The animals of each group were sacrificed 16 h, 3 days or 1, 2, 3 and 6 months postoperatively. RESULTS: Histologically, in one rat 16 h after 5-FU administration, we observed only a small necrotic focus of hepatocytes. Ultrastructurally, a mild vacuolization of cytoplasm, a decrease in mitochondria and an increase in lysosomes were observed. These abnormalities were restored 1 month later. CONCLUSION: Our results confirm that the particular dose, route and duration of 5-FU administration do not cause hepatotoxic morphological changes in the liver of healthy Wistar rats.

A new approach in the management of urothelial tumors using GM-CSF on marker lesions: an ultrastructural and immunohistochemical study on the macrophage population in bladder mucosa.

Our purpose was to investigate a new therapeutic model, GM-CSF-targeted immunomodulation on transitional cell carcinoma (TCC) marker lesions and to evaluate the immunologic response of the bladder mucosa. Eleven patients with pTa or pT1 bladder cancer were eligible for the study. All lesions were removed by transurethral resection (TUR) except for a marker lesion. All patients received 8 weekly instillations of 300 microg of GM-CSF, after which cystoscopy with bladder biopsies +/- TUR was repeated on adjacent urothelium or tumor or both. Paraffin-embedded sections were immunohistochemically stained with CD68, which labels monocytes and macrophages. The CD68+ cell population was evaluated as 1+ to 3+. Comparable specimens were routinely processed for ultrastructural analysis. Complete response was observed in 6 patients (55%), persistent tumor occurred in 4 patients (approximately 36.4%), and 1 patient (8.6%) showed recurrence. Immunohistochemically, an at least twofold increase in the number of the CD68+ cells was observed in all responders. Submicroscopically, migration of macrophages to the surface layer occurred. Macrophages showed an extensive lysosomal system and pseudopodia. This study indicates that the prophylactic treatment of TCC with GM-CSF may induce immunomodulatory effects on macrophage activities, which could be associated with the clinical evolution of the disease.

Natural killer (NK) cell assay within bladder mucosa of patients bearing transitional cell carcinoma (TCC) after interferon (IFN) therapy: an immunohistochemical and ultrastructural study.

The authors studied the number and the ultrastructural evidence of NK cell activation in the non-involved urothelium in patients with transitional cell carcinoma (TCC) of the urinary bladder, before and after transurethral resection (TUR) and interferon (IFN) therapy. Eight male patients, free of recurrence 1 year after TUR and IFN-a2b therapy, were studied. Each patient received 22 instillations of 50MU of IFN-a2b over a period of 1 year. Two specimens from the non-involved urothelium, one adjacent to and another away from the tumour, were obtained before and after therapy, for immunohistochemical and ultrastructural studies. The number of NK cells was evaluated immunohistochemically in paraffin sections with the CD57 monoclonal antibody, and their activation was detected by routine electron microscopy processing. Before treatment, few NK cells were randomly found in the lamina propria. At the end of therapy, however, their number increased and NK cells were found to infiltrate the urothelium, a finding that was not observed before treatment. The number of NK cells did not correlate with the degree of the inflammatory infiltrate of the mucosa. Moreover, the ultrastructural study revealed activation of NK cells with enhanced cytolytic activity. IFN therapy increases the number and promotes the activation of NK cells within the bladder mucosa. This finding could be of clinical significance in the prevention of tumour recurrence, given that NK cells enhance the immunological defense mechanisms of the bladder.

Ultrastructural study of the urothelial lysosomal system in patients with transitional cell carcinoma after transurethral resection and interferon therapy.

The epithelial cells of human bladder urothelium contain a prominent lysosomal system on the surface layer which involves autophagic, phagocytotic and excretory processes. The noninvolved urothelium of tumor-bearing patients, however, does not contain this well-developed lysosomal system. Interferon restores the differentiation of the urothelium. Its action on the lysosomal system, however, has not been investigated. We studied ultrastructurally the noninvolved urothelium of eight patients with transitional cell carcinoma who after transurethral resection and intravesicular interferon instillations for 2 years did not develop recurrence. We noted that the number and size of lysosomes increased, being most numerous within the cells of the surface layer. Characteristic large lysosomes with the morphology of multivesicular bodies were also evident. These multivesicular bodies were almost entirely filled with small vesicles containing a dense core. Our findings show that after 2 years of interferon administration a re-appearance of a highly developed lysosomal system of the noninvolved urothelium was evident. This restoration to the normal morphology with reappearance of the lysosomal system, which could be partly attributed to interferon therapy, may be of clinical significance for prevention of tumor recurrence.