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Biomedical subjects

M D'Incalci

Publications and source records attributed to M D'Incalci.

At least 253 records · Page 14Linked to original sources
PubMed1986

Differences in DNA damage produced by incorporation of 5-aza-2'-deoxycytidine or 5,6-dihydro-5-azacytidine into DNA of mammalian cells.

The effects of 5-aza-2'-deoxycytidine (aza-dCyd) and 5,6-dihydro-5-azacytidine (H2-aza-Cyd) on the integrity of DNA from several mammalian cell lines were compared using the alkaline elution technique. While both compounds have been shown to inhibit DNA methylation, a direct comparison of their effects on DNA structure has not previously been reported. Exposure of L1210 cells to H2-aza-Cyd (1-100 micrograms/ml) and simultaneous labeling with [14C]thymidine for 24 h resulted in the production of single-strand breaks in DNA, which were significantly repaired when cells were incubated in drug-free medium for an additional 24 h. This differed from our previous findings for aza-dCyd, confirmed here in parallel experiments, which showed that this compound produces alkali-labile lesions that persist for 48 h. The DNA effects of both drugs were significantly reduced when cells were prelabeled with [14C]thymidine, indicating that production of DNA lesions requires incorporation of the anomalous base. Studies utilizing pulse-labeled DNA indicated that aza-dCyd has little effect on the rate of DNA elongation, whereas H2-aza-Cyd produced a complete inhibition for at least 6 h after drug removal. The contrasting pattern of DNA damage induced by these compounds in L1210 was also observed in two human lymphoblastoid cells lines, one of which was derived from a patient with xeroderma pigmentosum. We had previously concluded that alkali-labile sites in DNA from aza-dCyd-treated cells probably arise due to the chemical instability of aza-dCyd. In contrast, incorporated H2-aza-Cyd is chemically stable. The single-strand breaks produced in H2-aza-Cyd treated cells were not of the alkali-labile type, and may represent an accumulation of DNA replication fragments and/or intermediates in an excision repair process. Thus, the DNA lesions produced by the two drugs have markedly different characteristics, and H2-aza-Cyd should not be considered to be merely a stable pharmacological congener of aza-dCyd.

Animals↗
PubMed1986

Effect of phenobarbital pretreatment on the metabolism and antitumor activity of hexamethylmelamine.

The effect of phenobarbital (PB) pretreatment on the N-demethylation and antitumor activity of hexamethylmelamine (HMM) was investigated in mice. In mice pretreated with PB, the levels of HMM in plasma, liver, and M5076 tumor were much lower than in mice treated with HMM alone. Plasma area under the curve (AUC) values were 15 +/- 4 versus 37 +/- 28 micrograms/ml X min, liver AUC values were 43 +/- 13 versus 246 +/- 5 micrograms/g X min, and tumor AUC values were 37 +/- 14 versus 109 +/- 24 micrograms/g X min. All of the N-demethylated metabolites except N2N4 dimethylmelamine in plasma, liver, and tumor also reached much lower levels in mice pretreated with PB. The antitumor activity of HMM was significantly antagonized by PB treatment in both M5076 reticular cell sarcoma and PC6 plasmocytoma of the mouse.

Altretamine↗
PubMed1986

Pharmacokinetics of etoposide in patients with abnormal renal and hepatic function.

Etoposide (VP16) pharmacokinetics was investigated in three groups of cancer patients: a control group of 18 patients with renal and hepatic function tests in the normal range; a group of 8 patients with renal insufficiency; and a group of 15 patients with abnormal hepatic function. In the control group plasma clearance (Clp), volume of distribution (Vd), and elimination half-life (t1/2 beta) of VP16 were, respectively, 22.8 +/- 1.0 (SE) ml/min/m2, 11.4 +/- 0.8 liters/m2, and 5.6 +/- 0.4 h. In patients with renal insufficiency Clp was 12.8 +/- 1.1 ml/min/m2, Vd was 20.8 +/- 4.9 liters/m2, and t1/2 beta was 19.2 +/- 4.7 h. A statistically significant correlation (P = 0.0000001) was found between VP16 Clp and creatinine clearance. In 12 of 15 patients with abnormal liver tests Clp, Vd, and t1/2 beta were, respectively, 27.9 +/- 2.7 ml/min/m2, 12.4 +/- 1.5 liters/m2, and 5.4 +/- 0.6 h and are thus similar to those of the control group. In the other three cases with abnormal liver function VP16 plasma levels were very low. In these cases VP16 t1/2 beta values were similar (5.1, 4.4, and 5.1 h) whereas Clp values (320, 87, and 96 ml/min/m2) and Vd values (142, 33, and 42 liters/m2) were much larger than in controls. These results suggest that VP16 doses should be reduced in patients with renal function impairment but not necessarily in patients with liver impairment. The high VP16 Vd and Clp values found in a subset of patients with liver impairment require further elucidation.

Adult↗
PubMed1985

High-performance liquid chromatographic assay for the determination of p-(3,3-dimethyl-1-triazeno)benzoic acid in mouse plasma.

A reproducible and sensitive method is described for assaying p-(3,3-dimethyl-1-triazeno)-benzoic acid (pCOOH-DMT) and for identifying the N-desmethyl metabolite, p-(3-methyl-1-triazeno)benzoic acid (pCOOH-MMT) using high-performance liquid chromatography. The method measures concentrations as low as 1.25 nmol/ml of plasma. Extraction efficiency of internal standard or of added triazenes averages 88% and the coefficient of variation of the method is less than 10%. pCOOH-DMT is stable at room temperature at pH 7.4, whereas pCOOH-MMT undergoes rapid decomposition (half-life 6 min). pCOOH-MMT is more stable in an albumin-containing solution or in plasma, but not in boiled 9000 g mouse liver. After 80 min incubation with a 9000 g mouse liver fraction and reduced nicotinamideadenine dinucleotide phosphate, only 24% pCOOH-DMT was metabolized. Plasma pharmacokinetic studies in mice treated with 200 mg/kg intraperitoneally showed that the potassium salt of pCOOH-DMT has a half-life of 67 min.

Animals↗
PubMed1985

Hexamethylmelamine, adriamycin, and cyclophosphamide (HAC) versus cis-dichlorodiamineplatinum, adriamycin, and cyclophosphamide (PAC) in advanced ovarian cancer: a randomized clinical trial.

After stratification according to diameter of the largest residual tumor, 120 previously untreated ovarian cancer patients were randomized to receive adriamycin and cyclophosphamide in combination with hexamethylmelamine (HAC) or cis-dichlorodiamineplatinum (PAC). The surgical response rates were 66% to HAC and 70% to PAC, with median times to progression of 14 and 22 months and median survival times of 23 and 24 months, respectively. In patients with residual tumor greater than 2 cm the surgical response rates to HAC and PAC were 56% and 63%, with complete response rates of 13% and 21%, respectively. In two of five complete responders to HAC there has still been no progression at 38 and 48 months, with a median response duration of 25 months. Only one of the nine complete responders to PAC has relapsed, at 33 months, while in the eight others response is maintained at follow-up times of 35-64 months. Myelosuppression was generally mild and similar in the two arms. No significant nonhematological toxicity was reported. It is concluded that at a median follow-up time of 36 months HAC is as effective as PAC in terms of response, duration of remission, and survival in previously untreated advanced ovarian cancer.

Adolescent↗
PubMed1985

A filter incubation method for the determination of potentially crosslinkable sites in DNA in mammalian cells.

A method for the determination of DNA monoadducts capable of forming interstrand crosslinks in mammalian cells is described. Such monoadducts were produced by brief treatment of cells with cis-diamminedichloro-Pt(II) (cis-DDP), 1-(2-chloroethyl)-1-nitrosourea (ClEtNU), L-phenylalanine mustard (L-PAM), or diaziridinylbenzoquinone (AZQ). The method is an alkaline elution procedure in which the DNA from lysed cells is incubated on polycarbonate filters at pH 10 and 37 degrees C. During this incubation, the progressive formation of interstrand crosslinking was observed in drug-treated cells. In the case of ClEtNU and AZQ, DNA strand breaks also formed, due to the presence of labile lesions in the DNA. This made quantitation of interstrand crosslinks difficult for these drugs. For cis-DDP and L-PAM, however, there was no significant production of strand breaks and the assay for interstrand crosslinks was quantifiable.

Binding Sites↗
PubMed1985

Horseradish peroxidase/hydrogen peroxide-catalyzed oxidation of VP16-213. Identification of a new metabolite.

VP16 was submitted to oxidation catalyzed by horseradish peroxidase (HRP) and H2O2 in phosphate buffer (pH 7.0). The product of the reaction, which has a high performance liquid chromatographic (HPLC) retention time different from the previously known metabolites of VP16, was identified as 1,2,3,4-tetradehydro-VP16 by 1H-NMR and mass spectrometry (MS) analysis. It was found to result from the loss of four hydrogens and the formation of an aromatic ring (ring C of VP16). This new product retains, in the 4' position of the E ring of VP16, the hydroxy group which is crucial for the antitumoral activity of podophyllotoxin derivatives. The reaction was linear in a wide range of VP16 concentrations and was dependent on the concomitant presence of peroxidase and H2O2.

Acetylation↗
PubMed1985

Metabolic studies of a podophyllotoxin derivative (VP16) in the isolated perfused liver.

The metabolism of VP16 was studied in isolated perfused rat liver. The rate of elimination into the medium and excretion in bile were determined by h.p.l.c. with u.v. detection. With high VP16 concentrations (180 micrograms/ml medium), the elimination half-life of the compound was prolonged markedly (156 v. 45 min for lower doses), the percentage recovered in bile was more than halved and drug accumulation in the hepatic tissue was three times greater. These findings indicate saturation of metabolism and of biliary elimination during high-dose treatment. The presence of glucuronides in the bile of VP16 perfused livers indicates that VP16 undergoes conjugation with glucuronic acid. Formation of picro isomer of VP16 in the liver also occurs.

Animals↗
PubMed1985

DNA alkali-labile sites induced by incorporation of 5-aza-2'-deoxycytidine into DNA of mouse leukemia L1210 cells.

The effects of 5-aza-2'-deoxycytidine on DNA in mouse L1210 leukemia cells were investigated using the alkaline elution technique. By comparing the DNA elution rate at pH 12.1 and 12.6, it was found that the drug produced DNA alkali-labile lesions. Alkali-labile sites were present only in DNA strands that were synthesized in the presence of the drug. They persisted for at least 48 h after drug treatment, and only after 72 h did the number of alkali-labile sites decline, thus suggesting a slow repair process. The production of alkali-labile sites was found to be concentration dependent and observable at concentrations which were effective in inhibiting the clonogenic viability of L1210 cells and which are attainable in vivo. 5-Aza-2'-deoxycytidine did not cause other DNA lesions such as DNA double-strand breaks or DNA-protein cross-links. Two hypotheses were considered to explain the origin of alkali-labile lesions in DNA that has incorporated 5-aza-2'-deoxycytidine: (a) the production of apyrimidinic sites by a glycosylase that recognizes and removes aza-cytosine from DNA and (b) the alkali-catalyzed decomposition of azacytosine residues to ring-opened products which could lead to alkali-induced DNA strand scission through a beta-elimination mechanism. The second hypothesis was considered to be the more probable and suggests that the alkali lability may be a means by which one could determine the extent of substitution and precise location of azacytosine residues or their ring-opened products in DNA.

Alkalies↗
PubMed1985

Pharmacokinetics of etoposide in gestochoriocarcinoma.

Etoposide (VP16) levels were determined by high-performance liquid chromatography assay in plasma, urine, and surgical specimens of patients with choriocarcinoma undergoing surgery after a dose of 100 or 200 mg/m2 given as a 1-hour infusion. The drug disappeared from plasma biexponentially, with a terminal half-life of 4.1 +/- 0.4 hours, an apparent volume of distribution of 9 +/- 1.1 L/m2, and clearance of 21.5 +/- 3.1 ml/minute/m2. Fifty and 740 minutes after the end of VP16 infusion, the drug concentrations in myometrial carcinoma or in normal myometrium were approximately 40%-50% of those in plasma; 25-180 minutes after the end of drug infusion, the concentrations of VP16 in lung metastases amounted to 19%-43% of those in plasma, whereas in normal lung, the concentrations of VP16 were 38%-61% of those in plasma. In subcutaneous tissue, VP16 levels were much lower than in plasma (about 5%-27%). About 50% of VP16 was eliminated in the urine as unchanged drug, glucuronide, or sulfate.

Choriocarcinoma↗
PubMed1985

Pharmacokinetics of teniposide in patients with ovarian cancer.

Pharmacokinetics of teniposide (VM26) after each of three doses were investigated by high-performance liquid chromatographic assay in eight patients with ovarian cancer with normal liver and renal functions. Treatment consisted of a first dose of 100 mg/m2 iv as a 1-hour infusion (Day 1), a second dose of 150 mg/m2 iv as a 1-hour infusion (Day 8), and a third dose of 150 mg/m2 as an approximately 1-day infusion (Day 22). Disappearance of VM26 from plasma followed a biexponential decay pattern. The mean terminal half-life (+/- SE) was 6.9 +/- 0.9 hours after the first dose, 6.1 +/- 0.7 hours after the second dose, and 9.7 +/- 1.4 hours after the third dose. VM26 levels in ascites were lower than those in plasma in the first hours after drug administration, but by 24 hours they were similar or slightly higher. Urinary elimination of VM26 as unchanged drug amounted to less than 10% of the dose.

Adult↗
PubMed1984

Central side effects of pentamethylmelamine: biochemical and behavioural studies.

The central side effects of pentamethylmelamine (PMM), an antitumoral agent, were studied on brain neurotransmitters from the biochemical and behavioural points of view. PMM causes a dose-related reduction in the body temperature and motility of mice. 100 mg/kg of PMM lowers the levels of noradrenaline (NA) and raises 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) in the telencephalon. A similar dose increased striatal levels of dopamine (DA) metabolites, homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC), at earlier times (30 min), reducing their levels at 2 hr. These effects disappear at longer times (4 hr). No changes were observed in the levels of 3-methoxytyramine (3-MT), the extraneuronal metabolite of DA. The serotonin metabolite 5-hydroxyindolacetic acid (5HIAA) was almost not affected. PMM and its metabolites do not displace [3H]-spiroperidol from mouse striatal binding sites. These data show that some of the neurological effects induced by PMM are associated with changes in the metabolism and/or release of brain catecholamines but are not mediated by direct action on DA receptors.

Altretamine↗
PubMed1984

Biochemical studies on the ability of pentamethylmelamine to interact in vivo with DNA and proteins in a sensitive murine ovarian reticular cell sarcoma.

The metabolism of 14C-PMM and its irreversible interaction with DNA and proteins were studied in M5076/73A reticular cell sarcoma, a murine solid tumor previously shown to be sensitive to the drug. Metabolism and irreversible binding were determined 0.25, 1, 8 and 104 hours after a single i.p. injection of radiolabelled PMM, tumor and liver macromolecular binding were compared with two differently 14C-labelled PMM, i.e. ring- and methyl-PMM. Ring-PMM derived macromolecular binding appeared to have more relevance in vivo and had a similar time profile in both liver and tumor. Ring-PMM derived DNA binding was then related to metabolic steps between PMM and 2,2,4,6 TMM and 2,2,4,6 TMM itself and 2,4,6 TriMM.

Altretamine↗
PubMed1984

Comparison of the antitumor activity of DTIC and 1-p-(3,3-dimethyl-1-triazeno) benzoic acid potassium salt on murine transplantable tumors and their hematological toxicity.

This study describes a comparison of 1-p-(3,3-dimethyl-1-triazeno)benzoic acid potassium salt (DM-COOK) and imidazole-4-carboxamide,5-(3,3-dimethyl-1-triazeno) (DTIC) with reference to antitumor activity on different murine tumors and hematological toxicity. DM-COOK appeared comparably or slightly more effective in L1210, P388, and M5 tumors in the mouse. However, when the treatment of mice bearing M5 with DM-COOK was combined with surgical removal of the primary tumor, the host's life-span was highly significantly prolonged. The two drugs showed similar activity in an M5 variant selected for resistance to cyclophosphamide. In L1210 Ha, a leukemia that is spontaneously resistant to DTIC, DM-COOK was not effective. Both DM-COOK and DTIC caused transient leukopenia with a maximum WBC fall of 57% and 71% compared with control values. DM-COOK's greater chemical stability might be an advantage, as the decomposition of DTIC is thought to lead to products responsible for some toxic effects in humans. Like other phenyldimethyltriazenes DM-COOK, is a good candidate for clinical trials because its water solubility eliminates formulation problems.

Animals↗
PubMed1984

Pharmacokinetic study of VM26 given as a prolonged IV infusion to ovarian cancer patients.

Plasma levels of VM26 were assayed by HPLC in six ovarian cancer patients with normal renal and liver function who received the drugs as an initial 1-h IV infusion of 80 mg/m2 followed by a 24-h IV infusion of 120 mg/m2. These doses and infusion rates were chosen on the basis of mean VM26 clearance values found in a previous study, with the aim of reaching plasma steady-state levels of approximately 6 micrograms/ml in a short time. Plasma steady-state levels of 4-10 micrograms/ml, close to those predicted theoretically, were in fact attained at 4-9 h during the second, slower infusion. Mean half-lives and clearance values were 8.6 +/- 1.1 h and 0.78 +/- 0.08 l/h/m2. Six percent of the VM26 dose was recovered as unchanged drug in the urines collected up to 24 h after the end of infusion. The glucuronide of VM26 aglycone (4'-demethylepipodophyllotoxin) was identified in the urine of all patients, in amounts corresponding to about 8% of the drug dose.

Animals↗
PubMed1984

Etoposide (VP-16-213) in malignant brain tumors: a phase II study.

Twenty-two consecutive patients with recurrent malignant brain tumors after radiation therapy and systemic combination chemotherapy with BCNU and vincristine, four of whom were not evaluable due to early death, were treated with etoposide (VP-16-213) (50-100 mg/m2 for five days every three weeks). Response, defined as improvement in both clinical examination and computed tomography scan in absence of glucocorticoids dosage increase, was observed in three (17%) of 18 evaluable patients, lasting greater than 21, seven, and two months, respectively. Six additional patients had stable disease for greater than 10, seven, four, four, three, and two months: all of them had improvement of clinical symptoms but no variation in their scans. Overall median survival from the start of VP-16-213 was 4.5 months (range, 1-23 + months), whereas patients with response or stable disease had a median survival of eight months. Overall, treatment was well tolerated. In 10 patients concomitant plasma and cerebrospinal fluid samples were evaluated with a high-performance liquid chromatographic method for drug assay. The concentration of VP-16-213 in cerebrospinal fluid was less than 1% that found in plasma, even in the two patients with response. The activity of etoposide in patients with malignant, lomustine-vincristine-resistant brain tumors suggests an interesting potential use for this drug.

Adolescent↗
PubMed1984

Pharmacokinetic studies of anticancer drugs in tumor-bearing animals.

The pharmacokinetics of antitumor agents is a relatively recent area of research, as lack of proper specific methodology for monitoring drug levels has always hampered major efforts. Although the relationship among administered dose, tissue concentration, and therapeutic and/or toxic effects remains extremely complex, a series of experimental and clinical studies provides information on the pharmacokinetic behavior of most anticancer agents in different conditions. This review article describes examples selected from the work of this Institute on several points which may be relevant to the use of these compounds: (a) factors influencing pharmacokinetics, such as genetic constitution of the host, presence of the tumor, dose, route of administration and schedule, organ insufficiency, and interactions with other drugs; (b) drug distribution in host tissues in relation to toxic effects; (c) drug distribution to secondary tumors (metastases); (d) importance of active metabolites; and (e) drug distribution and binding to intracellular target sites. An analysis of these factors shows that many aspects are still very poorly understood and require considerable further study.

Animals↗