Vinblastine-induced aggregates of smooth endoplasmic reticulum in proximal tubular cells of rat kidney

New features of renal lesion induced by stroma free hemoglobin

This study focused on the subacute renal lesions resulting from the infusion of stroma free hemoglobin (SFH), which remains under evaluation as a potential blood substitute despite limited renal toxicity observed in acute infusion. Four groups of rats received different doses of SFH (0.03, 0.48, 0.96, and 1.46 g, respectively) and were monitored, on alternate days, for their glomerular filtration rate over the course of 10 days. Another group of 6 rats receiving 0.96 g SFH was sacrificed at day 10 for examination of renal morphology. The low dose (0.03 g) of SFH infusion did not alter the creatinine clearance (Clcr) over 10 days. The Clcr decreased in rats receiving 0.48 g SFH but fully recovered at day 10. A persistent decrease in Clcr was observed in the groups of rats receiving 0.96 and 1.68 g of SFH. Tubular necrosis was the most prominent renal lesion distributed in the proximal tubules, especially in the convoluted segment of the juxtamedullary nephrons. Pearls' stained cytoplasmic granules and electron-dense lysosomal granules were found in surviving proximal tubules. Necrosis was the predominant mechanism of cell death. This study revealed for the first time proliferation of smooth endoplasmic reticulum in the proximal tubules after SFH treatment, where it appeared as nodular aggregates of tubulovesicular structures. The effect of SFH on the proximal tubule appeared to be a direct toxicity, and this toxicity was shown to be dose dependent. The presence of reversible toxicity indicated that a safety limit dosage for SFH infusion exists and that tolerance dose of SFH can be determined for clinical applications.

Kaposi's sarcoma in renal transplant recipients. Ultrastructural and immunoperoxidase study of four cases

Tissues from four cases of Kaposi's sarcoma developing in renal transplant recipients were studied by light and electron microscopic examination and by immunoperoxidase staining for Factor-VIII-related antigen. Ultrastructurally, the tumors in all four cases contained a variable mixture of cells, including endothelial cells, pericytes, fibroblasts, and myofibroblasts. These findings support the origin of Kaposi's sarcoma from primitive vasoformative mesenchyme. Immunoperoxidase staining for Factor-VIII-related antigen was limited to endothelial cells. In one case intracytoplasmic virus-like tubular complexes were seen. The significance of this finding is briefly discussed.

Tubular complexes of endoplasmic reticulum in lymphoblastic lymphoma: case report

Distinctive intracytoplasmic tubular complexes have been identified occasionally by electron microscopy in a wide variety of hematologic and nonhematologic disorders. The mechanism of induction and significance of these tubular complexes are unknown. Tubular complexes were identified in the majority of bone marrow lymphoma-leukemia cells in a patient with documented lymphoblastic lymphoma in lymph node. These complexes varied in size but in general ranged from 800--1500 nm, and consisted of masses of nonparallel, twisted, smooth, 40-nm tubules. Continuity with adjacent endoplasmic reticulum was evident in some of the complexes. Cytochemical characteristics of the malignant cells included strong, focal, paranuclear acid phosphatase reactivity and strong, stippled nuclear terminal deoxynucleotidyl transferase positivity. Flow cytometric analysis showed a DNA-RNA content pattern consistent with acute lymphoblastic leukemia and typical of T-cell lymphoma. This represents the first report of such tubular complexes in a presumed T-cell malignancy.

The effects of vinblastine on acinar cells of the exorbital lacrimal gland of the rat

The effects of vinblastine treatment on acinar cells of the rat exorbital lacrimal gland were studied by electron microscopy. Experimental animals of both sexes were given single intraperitoneal injections of (1) vinblastine (4 mg/kg body weight) at 1 to 24 h before sacrifice; (2) pilocarpine (20 mg/kg b.w.) for 1 h; or (3) vinblastine for 1 h followed by pilocarpine for 1 h. Vinblastine treatment caused a number of changes including autophagocytosis, formation of intracisternal granules, and alteration of secretory granules. These changes varied in extent and onset between male and female rats. In addition, the Golgi apparatus was reduced in size and dispersed throughout the cytoplasm. Mitotic figures were commonly observed. Moreover, vinblastine inhibited the pilocarpine-stimulated degranulation of the acinar cells. In view of the known anti-microtubular action of vinblastine, these results suggest that microtubules are involved in various aspects of the transport, packaging, and secretion of exportable proteins in the lacrimal gland. Additionally, autophagocytosis and alteration of secretory granules may partially result from the interaction of vinblastine with membranes.

Light microscopical and ultrastructural observations on the effect of vinblastine on ameloblasts of rat incisors in vivo. I. Short-term effect on secretory ameloblasts

The highly polarized secretory ameloblasts in the incisors of rats fixed by perfusion with glutaraldehyde two or three hours after intravenous administration of vinblastine sulfate at a dosage of 5 mg per 100 g body weight were studied in the light microscope and the electron microscope. The following effects were observed: 1. All cytoplasmic microtubules in the ameloblasts had vanished. This was not accompanied by the appearance of paracrystals of microtubular protein or macrotubules. 2. The ameloblasts preserved their external features of polarized cells but lost their ability to maintain normal orderly segregation of the cell constituents; i.e. their normal internal compartmentalization and polarity had vanished. 3. The ameloblasts lost their capability of directional translocation of the secretory granules towards the cell apex. 4. Secretory granules already translocated to the cell apex regurgitated in the cell and a probably delayed discharge of secretory material had started in abnormal site at the surface. 5. The normal arrangement of ribosomes into polyribosomes on the membranes of the rough endoplasmic reticulum was no longer present; the ribosomes were apparently distributed at random. 6. New secretion was inhibited or brought to a standstill but secretory material already present in the Golgi complex appeared to be transported normally. 7. The centriole had started to develop into a cilium in many of the cells. 8. The number of autophagic vacuoles had increased.