Surinder K. Aggarwal

ULTRASTRUCTURAL EFFECTS OF CISPLATIN

Publisher Summary This chapter discusses the mechanism of cisplatin action on normal and tumor cells and explores some possible avenues that can be followed to combat its toxic side effects. cis -Diamminedichloroplatinum II (cisplatin or DDP) has been approved for clinical use on a limited basis in treating testicular and ovarian tumors after an extensive testing in animal tumor-screening systems and clinical trials. Effective chemotherapy with cisplatin alone or in combination with other drugs on a wide variety of animal and human tumors is not free of side effects such as kidney toxicity, audiotoxicity, intestinal toxicity, and toxicity to the hemapoietic organs. Earlier studies using the electrophoretic analysis of proteinuria after cisplatin treatment have revealed tubular toxicity with preferential shedding of albumin and low molecular weight proteins. Glomerular injury is normally revealed by the presence of proteins with higher molecular weight than albumin. The detection of ligandin in the urine further indicates damage to pars recta of the proximal tubules.

Evidence for the holocrine nature of lipoid secretion by avian epidermal cells: A histochemical and fine structural study of rictus and the uropygial gland

Cells of the avian epidermis (rictus of the chicken), when examined under the light microscope following suitable fat staining, show similarities to epithelial cells of the uropygial gland of chicken and pigeon, an organ which is recognized both morphologically and functionally as a holocrine gland. Evidence thus far from electron microscopic studies strongly suggests that the skin of the bird is also a holocrine gland, although details of cytogenesis and secretion differ somewhat in the two organs.

Embryotoxicity of cisplatin in rats and mice

Cisplatin [cis-dichlorodiammineplatinum (II)], a broad spectrum antitumor agent, was tested for possible teratogenic and embryolethal effects on Wistar rats and Swiss Webster mice. Rats were given a single ip injection of 0.3, 1.0, 2.5, or 3.0 mg/kg cisplatin on Day 6, 8, 11, or 14 of gestation, whereas mice were given a single ip injection of 0.3, 3.0, 6.0, 8,0, or 13.0 mg/kg on Day 8 only. The embryonic LD50s in the rat were 2.88, 1.28, and 1.0 mg/kg for day 6, 8, and 11, respectively. There was no significant increase in embryolethality at any of the doses given on Day 14. The embryonic LD50 for mice was 5.24 mg/kg. An increase in the incidence of growth retardation or gross malformations was not discernable in the surviving fetuses with the number of dams used in this study. Cisplatin is highly embryolethal in rats and mice at dosages well below the adult therapeutic dosage in humans. This embryolethality is gestational stage-specific with the highest mortality corresponding to the period of rapid DNA replication in early organogenesis.

Platinum Drugs - Combined Anti-Lymphoproliferative and Nephrotoxicity Assay in Rats

SummaryA 4-day drug schedule was used to explore the efficacy and simultaneous toxicity of cisplatin and 30 other platinum (II) amines given IP to PVGxLew F1 hybrid rats at cumulative doses of 10–300 μmol/kg. Toxic effects monitored were stomach enlargement, kidney hypertrophy with tubular necrosis and proteinuria, evident visceral mucin, and lymphoid involution (thymus, spleen). Immunosuppressive effects were monitored as inhibition of the lymph node hypertrophy induced by grafting PVG spleen cells into each paw of F1 hybrids. No significant activity/toxicity was observed with ‘platinum-(pyrimidine) blues’. N-alkyl derivatives of cisplatin were less active/toxic and some had no immunosuppressant effect, though they are reported as effective antitumour agents (in mice). μ-Hydroxobridged aminoplatinum (II) dimers were highly toxic, effective immunosuppressants and their toxicity profiles were distinct from the dihalo or diaquo diaminoplatinum species.1,2-Diaminocyclohexane platinum derivatives showed a wide range of potency, all being much less nephrotoxic than cisplatin.

Some of the Properties of the Components of Drosophila ooplasm

Much of the information now available concerning the morphology of the mature oocyte and its coverings is summarized in Fig. 1. The ooplasm of mature oocytes contains two classes of large yolk spheres (-1-3 t in diameter). Alpha yolk spheres contain proteins (extractable from sections by pepsin, trypsin, or papain) and acidic lipids (which appear to be relatively unsaturated). They also contain small amounts of periodic acid/Schiff-positive material which is resistant to oc amylase. Beta yolk spheres are devoid of protein and contain (1) PA/S-positive polyglucosans which are extracted by a amylase, (2) alcian blue-positive, acidic polysaccharides, and (3) lipids which are relatively saturated. RNA is absent from spheres of both types. Two classes of ac yolk spheres can be distinguished under the electron microscope: cc spheres which have a homogeneous internal structure, and x2 spheres which contain populations of short rods embedded in a less dense, homogeneous background. The smaller o2 spheres generally contain small populations of large subunits, whereas large C2 spheres generally contain large populations of smaller subunits. Alpha spheres are membrane-enclosed, and the membrane is derived from the oolemma. /3 spheres are composed of large populations of clustered morula-shaped subunits, each about 50 my in diameter, and are devoid of a membranous envelope. Alpha,, oc and 3 spheres appear first at stages 8, 11, and 13, respectively; and they reach their maximum numbers and volumes at stages 10, 13, and 14, respectively. The ooplasm contains myriads of tiny mitochondria and lipid droplets. Mitochondria often attach themselves to the surface of f3 spheres. Stacks of annulate lamellae are abundant. The rough surfaced endoplasmic reticulum is in the form of long tubules which often anastomose with one another. Ribosomes are present in suspension in the background ooplasm. Ovaries dissected from adult females were suspended in Drosophila Ringer solution and centrifuged at 4 C for 10 minutes at 6,000 rpm. The ovaries were fixed, embedded in plastic, and studied with light and electron microscopes. In situations where the long axis of the stage 14 oocyte was parallel to the centrifugal field, the ooplasm separated into three morphologically distinct layers:

Cisplatin-induced inhibition of the calcium-calmodulin complex, neuronal nitric oxide synthase activation and their role in stomach distention.

Abstract Cisplatin (8 mg/kg; i.p.) treatment of Wistar rats produced no change in nitric oxide synthase (NOS) localization or its intensity for up to 5 days. However, immunohistochemicaly the levels of L-citrulline and the Ca2+-calmodulin complex were decreased after only 3 days. An in vitro experiment using an analog of calmodulin, MeroCalmodulin-1, showed that cis-diammine-diaquacisplatinum(II), a hydrolyzed form of cisplatin, inhibited the calmodulin conformational shift from occurring through a direct interaction with the calmodulin molecule. The results indicate that distention of the stomach was due to inhibition of neuronal NOS activation by a direct interaction between cisplatin and the calcium binding sites of the calmodulin molecule.

An analysis of factors responsible for resorption of embryos in cisplatin-treated rats

Pregnant rats were injected ip with 4 or 7 mg cisplatin/kg on gestation day (gd) 6 to study its effect on embryonal resorption. Serum concentrations of prolactin, luteinizing hormone (LH), and progesterone were determined by radioimmunoassay in pregnant rats, and related to the effects of cisplatin on the maintenance of pregnancy. The nocturnal prolactin surge on gd 9 was abolished in cisplatin-treated rats. Within 3 days after drug injection, LH concentrations decreased 39%, while serum progesterone decreased 63% by Day 10. A histochemical study of 20 alpha-hydroxysteroid dehydrogenase activity revealed no enzyme activity by gd 10. It is proposed that the cause of cisplatin-related embryonal resorption in rats may be due to decreases in hormone concentrations observed after drug treatment.

Effects of cisplatin and taxol on inducible nitric oxide synthase, gastrin and somatostatin in gastrointestinal toxicity.

Cisplatin (9 mg/kg) or taxol (20 mg/kg) treatment of Wistar rats produced a sharp decrease in inducible nitric oxide synthase (iNOS) and gastrin in the pyloric region of the stomach, and an increase in iNOS and somatostatin in the pancreatic islets. Nitric oxide (NO) functions as a relaxation factor in the smooth muscle of the muscularis mucosa while gastrin plays an important role in the gastroprotection of the mucosa through NO. It is proposed that a decline of the iNOS and gastrin after cisplatin or taxol treatments is related to distention of the stomach, and possibly nausea and vomiting. Hyperglycemia and glucose intolerance after cisplatin treatment may be caused by increases of somatostatin and iNOS in the pancreatic islets. Combination therapy with cisplatin and taxol seems to ameliorate various toxicities due to these two individual drugs.

Cisplatin-induced peptic ulcers, vagotomy, adrenal and calcium modulation.

Cytochemical and autoradiographic studies in Wistar rats [Crl:(WI)BR] show that cisplatin treatment (9 mg/kg) inhibits the release of acetylcholine from the axonal endings of the stomach smooth muscle resulting in bloating of the stomach and ulceration. Cisplatin also induces corticosteroid release from the adrenal gland stimulating peptic ulceration. Vagotomy helps ameliorate the effect but not eliminate it. Calcium supplementation restores normal neuromuscular function to gastric smooth muscle, thereby eliminating the gastro-intestinal toxicity due to cisplatin.

ACTIVATION OF MURINE PERITONEAL MACROPHAGES AFTER CISPLATIN AND TAXOL COMBINATION

Cisplatin and paclitaxel are potent antineoplastic agents. Their distinctly different mechanisms of action have prompted laboratory and clinical research into their use in combination therapies. Murine peritoneal macrophages treated with cisplatin and paclitaxel in combination elicit an increase in their number of lysosomes. Drug-treated macrophages, when co-incubated with sarcoma 180 cells, establish cytoplasmic contact and transfer lysosomes into tumor cells causing tumor cell lysis. In addition, analysis of tissue culture supernatants show increased levels of interleukin-1α and tumor necrosis factor-α. Our study shows that cisplatin and paclitaxel in combination enhance elements of the immune system with greater efficacy and potency than when used alone.