Effect of strain differences and tumor presence on microsomal drug metabolism in the guinea pig: brief communication.

In vitro drug metabolism in the Hartley guinea pig was compared with that in two inbred guinea pig strains used as carriers for the line 10 hepatoma. We observed minor differences in enzyme specific activity among the three strains. Three weeks after intradermal inoculation of Strain 2 guinea pigs with line 10 hepatoma cells, cytochrome P450 levels and aminopyrine demethylase activity were significantly decreased. Seven to 10 days after inoculation with the ascites form of the tumor, the activities of aniline and biphenyl hydroxylases, p-aminobenzoic acid N-acetyltransferase, and dichloronitrobenzene glutathione S-aryltransferase, in addition to those of cytochrome P450 and aminopyrine N-demethylase, were probably also described.

Metabolic activation of 4-ipomeanol in human lung, primary pulmonary carcinomas, and established human pulmonary carcinoma cell lines.

4-Ipomeanol (IPO) is a pulmonary-specific toxin that is metabolically activated by a cytochrome P450 pathway in lung tissue. In this study, IPO metabolism, as determined by measurement of [14C]IPO covalent binding, was evaluated in a diverse sampling of 18 established, human lung cancer cell lines as well as in normal lung tissue and primary lung carcinoma tissue obtained at the time of thoracotomy from 56 patients with lung cancer. [14C]IPO covalent binding in lung cancer cell lines ranged from 248 to 1,047 pmol of bound [14C]IPO per milligram of protein per 30 minutes (mean +/- SE = 547 +/- 62.2). IPO metabolism in normal lung tissue ranged from 12 to 2,007 pmol of covalently bound [14C]IPO per milligram of protein per 30 minutes (mean +/- SE = 549 +/- 60). In lung cancer tissue, values ranged from 0 to 2.566 pmol of covalently bound [14C]IPO per milligram of protein per 30 minutes (mean +/- SE = 547 +/- 60, P greater than .3). When patients were divided into smokers and current non-smokers (no tobacco products smoked for greater than 6 mo), no effects of cigarette smoking were observed for either normal lung tissue or lung tumor tissue (P greater than .1 in all instances). A wide range of IPO metabolic activity was observed among different histological classifications of lung cancer cell lines and of fresh lung cancer tissues. IPO metabolism was simultaneously compared in normal lung tissue and lung cancer tissue from individual patients, but no positive correlation was observed (r = .10; P greater than .30). The results clearly demonstrate a wide range of IPO metabolism in both normal and lung cancer cells and indicate that a wide diversity of human lung cancers possess the metabolic enzyme system(s) necessary for the bioactivation of IPO to a potentially cytotoxic intermediate. Therefore, the continued exploration for any possible therapeutic potential of IPO in patients with lung cancer appears warranted.

cis-Diamminedichloroplatinum (II)-DNA adduct formation in renal, gonadal, and tumor tissues of male and female rats.

cis-Diamminedichloroplatinum(II) (cisplatin), a potent anticancer agent, is thought to exert its cytotoxic effects through DNA damage. Using a polyclonal rabbit antisera which recognizes intrastrand bidentate deoxy(ApG)- and deoxy(GpG)-N7-diammineplatinum adducts, an enzyme-linked immunosorbent assay has been developed to quantitate this adduct in cisplatin-exposed DNA. Cisplatin-DNA adducts were measured in renal, gonadal, and tumor (sarcoma) tissues of Sprague-Dawley rats following i.v. or i.p. administration of cisplatin. When drug was administered i.v. to animals fed ad libitum adduct levels were highest in kidneys, 50% lower in s.c. sarcoma, and substantially lower in gonads. Under these experimental conditions, a large interindividual variability in adduct formation was observed in renal and tumor tissues, and adduct levels in some samples were too low to measure. Higher values among individuals were obtained using tissues of animals fasted overnight and treated i.p. Adduct levels following i.p. injections of drug were higher in kidneys and gonads of male rats than in kidneys and gonads of female rats. Analysis of tissue platinum content demonstrated higher platinum levels in kidneys of male rats than in kidneys of female rats, but the magnitude of this gender difference in total tissue platinum was not as great as that observed for adduct formation. When the influence of castration on adduct formation was investigated, adduct levels in kidneys of castrated females were higher than those in sham-operated females, but adduct levels in kidneys of the castrated male animals were not substantively different from those seen in sham-operated male controls. We conclude that the route of drug administration, diet, and hormonal status of the animal are factors that may influence cisplatin-DNA adduct formation in the rat.

Persistence of platinum-ammine-DNA adducts in gonads and kidneys of rats and multiple tissues from cancer patients.

The persistence of platinum-DNA adducts was investigated using normal rats as well as tissues from cancer patients receiving either cisdiamminedichloroplatinum(II) (cisplatin) or diamminecyclobutanedicarboxylatoplatinum(II) (carboplatin) for cancer chemotherapy. These studies used an enzyme-linked immunosorbent assay, established with a rabbit anti-cisplatin-DNA that is specific for intrastrand platinum-DNA adducts. The gonads and kidneys of male and female rats, sites for antitumor activity and toxicity, respectively, were monitored for cisplatin-DNA adduct formation after a single dose of drug and during multiple-dose exposures (once a wk for 3 wk). DNA adducts were measured by enzyme-linked immunosorbent assay 4 h and 2, 4, 7, and 14 days after administering a single i.v. injection of 8 mg/kg of cisplatin. Adduct profiles in renal tissues were similar in both males and females with adduct levels increasing between 4 h and 2 days, decreasing between Days 2 and 7, and stable between Days 7 and 14. In both sexes, levels of kidney DNA adduct measured 7 to 14 days after cisplatin injection comprised about 30% of the highest (Day 2) value. In testes and ovaries, adduct removal was complete by 4 days, and 40 to 50% of adducts present at Day 2 persisted until Days 7 and 14. A study of multiple dosing showed that adducts in renal and testicular DNA from rats given three weekly doses of 5 mg/kg of cisplatin had different accumulation profiles. In the testis there was a 2-fold accumulation of adduct after the third dose, while in the kidney adducts dropped with repeated dosing. In humans, the persistence of platinum-DNA adducts was studied in tissues from eight cancer patients who received their last dose of cisplatin or carboplatin chemotherapy between 1 day and 15 mo before autopsy. The patients had either ovarian cancer, breast cancer, or lymphoma, and the tissues studied included ovarian tumor, bone marrow, kidney, liver, spleen, lymph node, peripheral nerve, and brain. When samples were available from tumor tissues and from bone marrow within the same patient, adduct levels were similar in the two tissues. In addition, adducts were persistent for many months, since half of the individuals received their most recent platinum-drug therapy 7 to 15 mo before death. Overall, these studies demonstrate a widespread distribution and high degree of platinum-DNA adduct persistence in both animal and human tissues subsequent to cisplatin or carboplatin treatment.

Distribution and disposition of platinum following intravenous administration of cis-diamminedichloroplatinum(II) (NSC 119875) to dogs.

cis-Diamminedichloroplatinum(II) is an antineoplastic drug that is undergoing a renewed clinical interest as a drug for use in combination regimens. In order to increase the understanding of the pharmacokinetics of this drug, the plasma clearance and organ distribution of platinum were followed in female beagle dogs treated with a single i.v. dose of cis-diamminedichloroplatinum(II). Plasma levels of platinum were determined by flameless atomic absorption spectrometry and showed a distinctly biphasic clearance pattern with a rapid-phase half-time of considerably less than 1 hr and a slow-phase half-time of nearly 5 days. During the first 4 hr after treatment, plasma levels fell by 90% while 60 to 70% of the applied dose was recovered in the urine. Sixteen tissues plus plasma, bile, and urine were routinely analyzed for platinum content. An easily measurable plasma concentration of platinum was still detectable 12 days after treatment, with no significant change in plasma concentration between Days 4 and 12. Initial concentrations of platinum were highest in organs of excretion, gonads, spleen, and adrenals but remained significantly elevated only in kidney, liver, ovary, and uterus, where a tissue: plasma ratio of 3 to 4 was maintained for as long as 6 days posttreatment. The apparent in vitro binding of platinum to dog plasma and to bovine serum albumin was studied by ultrafiltration and increased progressively during 48 hr of incubation at 37 degrees.

Profiles of prostaglandin biosynthesis in normal lung and tumor tissue from lung cancer patients.

prostaglandin (PG) biosynthetic profiles from endogenous arachidonic acid were determined by capillary gas chromatography-mass spectrometry in matched fresh normal lung (NL) and lung cancer (LC) tissue fragments obtained from 42 individual LC patients at the time of diagnostic thoracotomy. The histological diagnoses represented were squamous cell carcinoma (N = 20), adenocarcinoma (N = 7), small cell carcinoma (N = 4), mixed cell carcinoma (N = 2), bronchioloalveolar cell carcinoma (N = 2), large cell undifferentiated carcinoma (N = 3), bronchial carcinoid (N = 1), and metastatic tumors (N = 3). When PG biosynthesis was determined in NL tissue separately, low mean levels of PGE2 and PGF2 alpha (less than 2 pmol/mg protein/15 min), intermediate levels of PGD2 and 6-keto-PGF1 alpha (6KPGF1 alpha) (2-7 pmol/mg protein/15 min), and high levels of thromboxane B2 (TXB2) (greater than 7 pmol/mg protein/15 min) were observed. There was no particular correlation with cigarette smoking history and PG biosynthesis in NL. When PG production in LC tissue was evaluated separately, high levels of PGE2, PGF2 alpha, and 6KPGF1 alpha as well as TXB2 and low levels of PGD2 were noted. In addition, LC tissue from cigarette smokers demonstrated elevated levels of PGE2, 6KPGF1 alpha, and TXB2 when compared to current nonsmokers with LC (P less than 0.05 in all instances). Simultaneous comparison of PG production in matched LC and NL tissue from individual patients indicated increased biosynthesis of PGE2 and PGF2 alpha and low levels of PGD2 in LC compared to NL tissue (P less than 0.05 in all instances; paired, two-tailed, Student's t test). Individual comparison of PG biosynthesis according to LC histological cell type revealed that PGE2 and PGF2 alpha were consistently elevated in all four common primary LC histological cell types, the only exception being large cell undifferentiated carcinoma. Interestingly, this latter LC histological cell type presented a unique profile with lower levels of PGE2 and PGD2 in LC than in NL tissue (P less than 0.05 in both instances). In addition, the biosynthesis of all 5 PGs studied was consistently higher in primary than metastatic adenocarcinomas of the lung (P less than 0.05 in all instances). No differences were observed in NL and LC tissue for the major LC histological cell types when PGD2, TXB2, or 6KPGF1 alpha biosyntheses were compared. These findings indicate that the profiles of PG biosynthesis in LC and NL tissue from individual patients may differ substantially. These differences may reflect, in part, contributions to the PG biosynthetic profile unique to malignant cells.

Novel intrapulmonary model for orthotopic propagation of human lung cancers in athymic nude mice.

A major impediment to the study of human lung cancer pathophysiology, as well as to the discovery and development of new specific antitumor agents for the treatment of lung cancer, has been the lack of appropriate experimental animal models. This paper describes a new model for the propagation of human lung tumor cells in the bronchioalveolar regions of the right lungs of athymic NCr-nu/nu mice via an intrabronchial (i.b.) implantation procedure. Over 1000 i.b. implantations have been performed to date, each requiring 3 to 5 min for completion and having a surgery-related mortality of approximately 5%. The model was used successfully for the orthotopic propagation of four established human lung cancer cell lines including: an adenosquamous cell carcinoma (NCI-H125); an adenocarcinoma (A549); a large cell undifferentiated carcinoma (NCI-H460), and a bronchioloalveolar cell carcinoma (NCI-H358). When each of the four cell lines was implanted i.b. using a 1.0 X 10(6) tumor cell inoculum, 100 +/- 0% (SD) tumor-related mortality was observed within 9 to 61 days. In contrast, when the conventional s.c. method for implantation was used at the same tumor cell inoculum, only minimal (2.5 +/- 5%) tumor-related mortality was observed within 140 days (P less than 0.001). Similarly, when a 1.0 X 10(5) or 1.0 X 10(4) cell inoculum was used, a dose-dependent, tumor-related mortality was observed when cells were implanted i.b. (56 +/- 24% or 25 +/- 17%) as compared with the s.c. method (5 +/- 5.7% or 0.0 +/- 0%) (P less than 0.02 and P less than 0.05, respectively). Most (greater than 90%) of the lung tumors propagated by i.b. implantation were localized to the right lung fields as documented by necropsy and/or high-resolution chest roentgenography techniques which were developed for these studies. The intrapulmonary model was also used for establishment and propagation of xenografts derived directly from enzymatically digested, fresh human lung tumor specimens obtained at the time of diagnostic thoracotomy and representing all four major lung cancer cell types as well as a bronchioloalveolar cell carcinoma. Approximately 35% (10 of 29) of the fresh primary human lung tumor specimens and 66% (2 of 3) of tumors metastatic to the lung were successfully propagated i.b. at a 1.0 X 10(6) tumor cell inoculum, whereas only 20% (1 of 5) of the specimens were successfully grown in vivo via the s.c. route from a 1.0 X 10(7) tumor cell inoculum.(ABSTRACT TRUNCATED AT 400 WORDS)

The role of STATs in inflammation and inflammatory diseases.

The immune response is regulated by the concerted action of pro- and anti-inflammatory cytokines. The deregulation of this process causes immunological disorders like allergic and autoimmune diseases. The Janus Kinase (JAK)--Signal transducer and activator of transcription (STAT) pathway is one major signaling pathway converting the cytokine signal into gene expression programs regulating the proliferation and differentiation of the immune cells. Several members of the STAT protein family in particular STAT1, STAT2, STAT3, STAT4 and STAT6 act as transcription factors in modulating pro- and anti-inflammatory responses. Here we review the evidence for the involvement of the different STAT proteins in inflammation, autoimmune and allergic diseases. We discuss novel approaches to interfere with the function of these signaling transcription factors for therapeutic purpose.

Effect of probenecid and N'-methylnicotinamide on renal handling of cis-dichlorodiammineplatinum-II in rats.

The renal handling of cisplatin was investigated in Sprague-Dawley rats in the presence and absence of probenecid and N'-methylnicotinamide. The renal clearance of free cisplatin was not significantly different from the glomerular filtration rate. N'-Methylnicotinamide, an organic cation, did not affect cisplatin clearance. Administration of probenecid, an organic anion, resulted in a significant increase in cisplatin clearance to 169% of the glomerular filtration rate. These results suggest that cisplatin or a metabolite is excreted by the kidney by a complex process which includes glomerular filtration, secretion and active reabsorption via the organic acid transport system.

The effect of sodium thiosulfate on subcellular localization of platinum in rat kidney after treatment with cisplatin.

Female Sprague-Dawley rats were given 10 mg/kg of i.v. cis-diammine-dichloroplatinum(II) (cisplatin) simultaneously with i.v. sodium thiosulfate (STS) at a 200-fold molar excess to cisplatin, then subcellular (nuclei, mitochondria, microsomes, cytosol) distribution of platinum within rat kidney cells was determined 15 min, 1 h, 8 h and 24 h after cisplatin injection. Blood urea nitrogen levels were measured in rats treated in the same manner described above. STS was found to block cisplatin-induced nephrotoxicity. However, differences in platinum concentrations in total homogenate or each subcellular fraction between STS-treated rats and controls were not significant enough to fully account for the drastic protective effect of STS against cisplatin nephrotoxicity.

Polyclonal antibodies to quantitate cis-diamminedichloroplatinum(II)--DNA adducts in cancer patients and animal models.

cis-Diamminedichloroplatinum (II) (cis-DDP), the antitumor drug, is cytotoxic in vitro primarily by binding to DNA and disrupting its normal functions. We have studied cis-DDP modification of DNA in nucleated peripheral blood cells (buffy coat cells) of testicular and ovarian cancer patients receiving cis-DDP chemotherapy, and of untreated controls. Using a highly sensitive enzyme-linked immunosorbent assay (ELISA) with an antiserum specific for the bidentate intrastrand N7-deoxyguanosine adduct, blood cell DNA was assayed at multiple times during courses of cis-DDP treatment. A total of 138 samples were analyzed from 54 individuals. Of these, all samples from 18 untreated controls were negative, while 44 out of 120 samples from cis-DDP patients were positive. Testicular and ovarian cancer patients receiving chemotherapy on the first course, and given cis-DDP in 21- or 28-day cycles (five days of drug infusion followed by two or three drug-free weeks) accumulated cis-DDP-DNA adducts in blood cell DNA as a function of dose. Patients receiving their first course of cis-DDP on 56-day cycles and those given high doses of this drug after failing other chemotherapy showed much slower adduct accumulation than patients receiving their first course on 21- or 28-day cycles. Adduct accumulation, in positive patients, occurred both as a function of total cumulative dose and with increasing cycle number, suggesting that adduct removal took at least a month in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in plasma pharmacokinetics of cisplatin in tumor-bearing rats.

Rats were inoculated s.c. with the Walker 256 solid carcinosarcoma, and when tumors reached a weight of approximately 2-3 g, pharmacokinetics, tissue distribution, and urinary excretion of 195mPt-labelled cisplatin were studied. Cisplatin was given i.v., blood was sampled through arterial cannulae, and data were fitted to a three-compartment model. Distribution half-times were prolonged two- to threefold in tumor-bearing animals, although there was no change in elimination half-time. Initial and steady-state volumes of distribution were also increased in tumor-bearing animals. There was no change in AUC, urinary excretion, tissue distribution, or plasma protein binding. The results indicate that a solid tumor represents an additional compartment for distribution of cisplatin and alters the rate at which cisplatin is distributed from the plasma.

Increased tissue deposition and decreased excretion of platinum following administration of cisplatin to cisplatin-pretreated animals.

Guinea pigs were pretreated IP with cisplatin (10 mg/kg) for various times before IV administration of 195mPt-labeled cisplatin. Concentrations of 195mplatinum were greater in tissues of pretreated animals than in those of control animals. Amounts of 195mplatinum in subcellular fractions from pretreated rabbits were similarly greater in pretreated animals. Amounts of radioactivity appeared to be greatest in animals receiving a larger number of pretreatment injections, even though the total amount of cisplatin administered was equal in all groups. BUN was elevated on day 1 after the radioactive dose only in those animals which had been pretreated. Urinary excretion of platinum was significantly less in pretreated than in control animals. It appears that pretreatment with cisplatin damages the kidney severely enough for subsequent doses of cisplatin not to be excreted as efficiently, thus leading to a greater tissue deposition of platinum in pretreated animals.

The effect of cisplatin on renal ATPase activity in vivo and in vitro.

The effect of cisplatin on ATPase activity was determined in vitro and in vivo to investigate the correlation between nephrotoxicity and the inhibition of ATPase activity by cisplatin. Purified Na,K-ATPase was preincubated for 0-240 min with cisplatin at concentrations of 50-800 microM in vitro before the determination of enzyme activity. Although ATPase activity was reduced by cisplatin, either a high concentration of cisplatin (280 microM) or a long period of preincubation (160 min) with cisplatin was required to obtain 50% inhibition of ATPase activity. Similar in vitro experiments using kidney homogenate from female Sprague-Dawley rats instead of purified Na,K-ATPase were performed. Activity of Na,K-ATPase in rat kidney homogenate was inhibited by 50% after 110 min preincubation with 800 microM cisplatin or 160 min preincubation with 400 microM cisplatin. Female Sprague-Dawley rats were given 5, 7 or 10 mg/kg of cisplatin IV and BUN level, ATPase activity and Pt concentration in kidney homogenate were evaluated 1 h, 6 h, 1 day, 3 days, and 5 days after cisplatin injection. In rats given 10 mg/kg cisplatin a significant increase of BUN was observed on days 1, 3, and 5. In rats treated with 5 or 7 mg/kg of cisplatin BUN was increased on days 3 and 5. Normal ATPase activity, however, was preserved until day 3 at all doses. The highest concentration of Pt observed in kidney tissue was 19.3 micrograms/g tissue. This value was insufficient to inhibit ATPase activity significantly in vitro. Thus, it seems unlikely that the inhibition of ATPase activity is the cause of nephrotoxicity, although cisplatin can affect ATPase activity.

Effects of the diuretics mannitol or acetazolamide on nephrotoxicity and physiological disposition of cisplatin in rats.

The anticancer drug cisplatin has been known to produce severe renal lesions characterized by high levels of blood urea nitrogen (BUN), toxic nephrosis, and platinum (Pt) retention in the kidney. The effect of IV pretreatment with acetazolamide (ACZ) 30 min before or mannitol (MAN) immediately prior to IP administration of 5 mg/kg cisplatin on Pt excretion, tissue distribution, and nephrotoxicity was investigated in male F344 rats. ACZ pretreatment reduced the cisplatin-induced nephrotoxicity, as indicated by only a slight elevation of BUN, a milder histopathologic lesion, and a more rapid recovery of renal function and structure. Although MAN-pretreated animals exhibited similar changes in BUN to ACZ-pretreated animals, the renal damage was similar to that seen in animals treated with cisplatin alone. A reduction of kidney Pt content was observed with both diuretics, although there was significantly less retention after ACZ pretreatment. The diuretic ACZ was more effective than MAN in reducing the renal lesions induced by cisplatin and it might be clinically useful in preventing cisplatin nephrotoxicity.

Alterations in hepatic and renal levels of glutathione and activities of glutathione S-transferase from rats treated with cis-dichlorodiammineplatinum-II.

Adult female rats were treated intraperitoneally with 8 mg/kg of cis-dichlorodiammineplatinum(II). At various times after treatment 1, 3, 5, 8, 12 days replicate animals were killed and liver and kidney cytosols examined for activity of glutathione-dependent transferase activities and levels of glutathione. Hepatic levels of glutathione were depressed by 13-28% at 1, 3, 5 days after dosing. Renal levels of glutathione were increased by 3-5 fold at 8 and 12 days after drug administration. Renal levels of glutathione were decreased at nearly all times studied with a nadir at 5 days. Activity of glutathione s-acryl transferase was increased and S-epoxidetransferase was decreased at 5, 8, 12 days after dosing. When cisplatinum was added to incubation mixtures in vitro, no changes in enzyme activities were observed. When cisplatin and reduced glutathione were determined chromatographically in tissue cytosols from treated rats, 30% of the recovered platinum was associated with glutathione. In tissue cytosols, greater than 95% of the total platinum content was retained in the supernatant when protein was precipitated with trichloroacetic acid, while only 3-5% of the protein was retained.

Pharmacokinetics and protein binding of cis-dichlorodiammine platinum (II) administered as a one hour or as a twenty hour infusion.

The pharmacokinetics of cis-dichlorodiam-minoplatinum (II) (cisplatin) have been studied in seven patients, of whom four received the drug as a one hour infusion and three received it as a 20 h infusion. The patients receiving the drug over one hour exhibited biphasic clearance of total platinum with a rapid initial phase (8.7-22.5 min) and a prolonged second phase (30.5-106 h). Free (ultrafilterable) cisplatin was readily detectable in this group and was rapidly cleared (half-life about 22 min). The volume of distribution of the drug was 50.3-65.6 liters and it was 26.6-50% excreted in the urine in 48 h. In the patients receiving the 20 h infusion, a more complex plasma elimination curve was seen, with the appearance of a secondary peak. Free drug was not detectable in these patients and they showed less urinary excretion (21.4-25.9% at 48 h) than the one hour group. Cisplatin was bound to several plasma proteins, including albumin, transferrin, and gamma-globulin. The data indicate that cisplatin is retained in the body more extensively after a 20 h infusion than after a one hour infusion.

Interaction of the oncolytic drug, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea with the mixed-function oxidase system in rats.

Effects of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) on the hepatic mixed-function oxidase system in male rats were studied both in vivo and in vitro. A single dose of CCNU (40 mg/kg) caused a significant reduction in hepatic mixed-function oxidase activities within 3 days after administration. The depression was prolonged for cytochrome P-450, total haem and the metabolism of several type I substrates lasting up to 10 weeks after a single dose. By contrast, aniline hydroxylase, cytochrome b5 and NADPH-cytochrome c reductase activities returned to near control levels after week two. Microsomal enzymes in the kidneys of treated animals however, were unaltered. Serum glutamic pyruvic and glutamic oxaloacetic transaminase and bilirubin levels, indicators of hepatotoxicity, were greatly elevated 3 days after CCNU treatment. These parameters fell rapidly but were still above control levels to the end of the 10-week study. When added in vitro, CCNU reduced apparent cytochrome P-450 content and the metabolism of type I substrates in microsomes from untreated, phenobarbital (PB) and 3-methylcholanthrene (3-MC)-pretreated rats. Total haem and NADPH-cytochrome c reductase were not affected whereas aniline hydroxylase activity was activated. CCNU interacted with hepatic microsomes to produce a type I difference spectrum.

Ototoxicity of cisplatin vs. platinum analogs CBDCA (JM-8) and CHIP (JM-9).

Cis-diamminedichloroplatinum (cisplatin), a divalent platinum compound and cell-cycle nonspecific chemotherapeutic agent, produces a permanent high-frequency sensorineural hearing loss and a dose-related cumulative renal insufficiency with tubular necrosis and interstitial nephritis. Synthetic platinum analogs are presently being tested to identify an analog with greater antitumor activity, but less ototoxicity and nephrotoxicity than cisplatin. The objectives of this study were to analyze the potential cochlear and nephrotoxic effects of two synthetic platinum analogs presently in phases I and II of clinical trials, CBDCA [JM-8 or cis-diammine, 1,1-cyclobutane dicarboxylato (2)-0,0(1)-platinum (NSC-241240)] and CHIP [JM-9 or cis-dichloro-trans-dihydroxybisisopropylamine platinum IV (NSC-256927)]. Cytocochleography, auditory brain-stem evoked response (ABR), double-blind light microscopy of renal tissues, and gamma emission analysis of 195mpt localization in viscera and inner ear were employed in the evaluation of cisplatin and platinum analogs (JM-8 and JM-9) in adult guinea pigs. Final results indicate that the investigational chemotherapeutic analogs CBDCA (JM-8) and CHIP (JM-9) do not produce the ototoxicity and nephrotoxicity characteristic of cisplatin. Furthermore, these findings demonstrate 195mpt localization in the vestibular labyrinth and confirm previous platinum distribution studies in the organ of Corti and stria vascularis tissues.

Ototoxic and nephrotoxic effects of combined treatment with cis-diamminedichloroplatinum and kanamycin in the guinea pig.

Ototoxic and nephrotoxic potentiation with concomitant cis-diamminedichloroplatinum, or cis-platinum II (CSP), and aminoglycoside therapy was investigated in the guinea pig. We evaluated possible potentiation of the toxic effects of CSP and kanamycin compared with CSP alone in the inner ear and kidney and quantitatively localized CSP in the cochlea with gamma emission analysis of 195mPt. Kanamycin-treated animals demonstrated cytocochleograms and ABR waveforms, absolute latencies, and interwave latencies for waves I, II, and III similar to control animals at our maximum level of acoustic stimulation. CSP treatment produced 60% to 70% mean outer hair cell (OHC) loss in the basal turn of the cochlea, a reduction in ABR waveform and amplitude, and an increase in latencies of ABR waves I, II, and III. Combined CSP and kanamycin treatment produced 90% to 100% mean OHC loss in all rows of the basal turn of the cochlea, with no discernible ABR waveform corresponding to the region stimulated by a 4500 to 7000 Hz acoustic click. Combined treatment produced the most significant cortical medullary tubular necrosis and interstitial nephritis. Furthermore, this study reports for the first time localization of platinum in the inner ear.