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Biomedical subjects

S T Crooke

Publications and source records attributed to S T Crooke.

At least 253 records · Page 14Linked to original sources
PubMed1981

Single-strand and double-strand deoxyribonucleic acid breaks produced by several bleomycin analogues.

Production of single-strand breaks (ssb) and double-strand breaks (dsb) of PM2 phage DNA by several structurally related bleomycin (BLM) analogues was studied by gel electrophoresis. BLM A2 and BLM B2 produced a comparable extent of dsb. In various experiments, BLM A2 and BLM B2, at 22-41 ng/mL, degraded 50% of the form I DNA into 33-38% form II and 12-17% form III DNA. BLM B1' produced ssb and dsb at a ratio similar to that of BLM A2, but both at a rate less than half that of BLM A2. Phleomycin (PLM) D1 induced an equivalent amount of ssb but only one-eighth of dsb induced by BLM B2. The relatively lower extent dsb production for PLM D1 was observed either in borate buffer (pH 9.5) or in Tris-HCl buffer (pH 7.5) and in the presence or absence of exogenous Fe(II). Deamido-BLM A2 produced ssb to an extent approximately half that of BLM A2 and dsb to less than one-eighth that of BLM A2. The following conclusions were drawn. (1) BLM analogues produced ssb and dsb to different extents and ratios. (2) The ratio of dsb to ssb varied depending on the analogue, indicating a lack of a direct correlation between ssb and dsb. (3) The extent of ssb and dsb was affected by modifications on both the C- and N-terminal half-molecules of BLM: modification of either the N-terminal amide or the bithiazole greatly reduced dsb, whereas changes in structure or charge in the C-terminal amine affected ssb and dsb to a similar extent.

Bleomycin↗
PubMed1981

Phase II evaluation of mitomycin C (MMC) in children with refractory solid tumors using the single high-intermittent-dose schedule.

Nine evaluable patients with refractory solid tumors received mitomycin C as a single intravenous injection at a dose of 20 mg/m2 at 6- to 8-week intervals. Toxicity was tolerable. One patient with Wilms' tumor had a transient decrease in liver size. Pharmacokinetic data on three patients have suggested that the disposition of mitomycin C were comparable to those obtained in adults.

Adolescent↗
PubMed1981

DNA breakage activity of the methanol extract of auromomycin.

The constituents of the antitumor agent auromomycin have been analyzed to determine their DNA-breakage activities. Spectral analysis showed that the methanol extract contained 70% of the non-peptide chromophore, whereas the residue contained 20%. Amino acid analysis of the methanol extract showed that it contained 21%-26% of the original auromomycin polypeptides. The DNA-degradation activity of the extract was 121% +/- 28% of that of the untreated auromomycin, whereas that of the residue was only 22% +/- 3.8%. Mixing of the residue and the methanol extract resulted in the loss of three-fourths of the total activity. Agarose gel electrophoretic analysis showed that the single-strand DNA breakage activity of the methanol extract was 6.5-fold greater than that of the double-strand DNA-breakage activity. The difference in the total DNA-cleavage activity of the untreated, methanol-treated, and remixed auromomycin preparations may suggest the occurrence of certain non-peptide chromophore-polypeptide interactions in both the untreated and the remixed preparations. This is consistent with the fluorescent changes observed upon mixing of the extract and residue. Fractionation of the methanol extract by Sephadex chromatography revealed that several column fractions which were enriched with non-peptide chromophore relative to the polypeptides contained in them still had significant DNA-degradation activity. These studies suggest that the non-peptide chromophore in the auromomycin preparation may contribute to most of the observed DNA breakage activity.

Amino Acids↗
PubMed1981

Pharmacokinetics of carminomycin in dogs and humans. Preliminary report.

Carminomycin was administered to four dogs and two human patients as a single intravenous dose. Plasma samples were obtained and assayed for carminomycin and carminomycinol by high pressure liquid chromatography with fluorescence detection. The plasma disappearance of carminomycin could be described by a three-compartment open model. Distribution was rapid and the apparent volume of distribution was greater than 100 l/m2 in both species. The terminal half-life of drug was 86 h in dogs and 20 h in humans. In both dogs and humans carminomycinol concentrations rapidly surpassed carminomycin levels, and terminal half-lives were longer than for the parent compound in the two species. Since carminomycinol has antitumor activity and host toxicity, this metabolite may play an important role in the efficacy and toxicity of carminomycin therapy.

Animals↗
PubMed1981

Comparison of the response of synchronized HeLa cells to talisomycin and bleomycin.

The cytotoxic activities of the antitumor antibiotics talisomycin (TLM) and bleomycin (BLM), were compared with asynchronous and synchronous populations of HeLa cells. The sensitivities of asynchronous and synchronous cells to TLM and BLM were expressed as biphasic dose-response survival curves. Of the cell cycle populations investigated, mitotic phase cells were the most sensitive and G1 phase cells the most resistant to tLM and BLM cytotoxic activity. A significantly greater portion of mid-G1 cells was more resistant to TLM than to BLM. Mid-S-phase cells showed greater resistance to TLM than to BLM in the initial portion (primary slope) of the dose-response curve.

Antibiotics, Antineoplastic↗
PubMed1981

Inhibition of bleomycin-induced DNA breakage by superoxide dismutase.

Inhibition of bleomycin (BLM)-induced DNA breakage by superoxide dismutase (SOD) has been reported and presumed to be due to its removal of the superoxide free radicals generated by BLM in the presence of iron(II). We have studied the possibility that the inhibitory effect might result from DNA-binding of SOD. The effect of copper-zinc SOD on BLM-induced DNA degradation was investigated using the PM-2 DNA fluorescence technique. PM-2 DNA was incubated with BLM in the presence or absence of native and heat-inactivated copper-zinc SOD as determined by the epinephrine autoxidation method. The concentrations of SOD required to inhibit 50% PM-2 DNA degradation for the native and the inactivated SOD were 100 and 120 microgram/ml, respectively. Analysis of the reaction mixture by agarose gel electrophoresis confirmed the absence of DNA degradation by BLM in the presence of either form of SOD. PM-2 DNA was shown to bind native or inactivated SOD by Sephadex G-100 column chromatography, fluorescence-quenching studies, and agarose gel electrophoresis. Thus, these results indicate that SOD is able to bind to PM-2 DNA and inhibit BLM-induced degradation independently of its free radical-scavenging activity. The inhibitor was more effective against BLM than other compounds which degrade PM-2 DNA. This suggests that SOD may bind to BLM-binding and/or BLM degradation sites in PM-2 DNA, and the observed inhibition is unrelated to its effects on free radicals.

Binding Sites↗
PubMed1981

DNA supercoiling, shortening, and induction of single-strand regions by cis-diamminedichloroplatinum(II).

cis-Diamminedichloroplatinum(II) was found to bind to covalently closed circular supercoiled, covalently closed circular nonsupercoiled, and single-strand broken relaxed PM2 DNA and induce different types of DNA conformational changes. Using Kleinschmidt's technique, it was found that binding of cis-diamminedichloroplatinum(II) decreased the DNA length to 75% of the original single-strand broken relaxed DNA without inducing superhelical conformational changes. cis-Diamminedichloroplatinum(II) also shortened the length of covalently closed circular nonsupercoiled DNA before a supercoiled conformation was generated. Single strand-specific nucleases were used to detect drug-induced DNA structural alterations. Local single-strand regions or regions of denaturation were detected by S1 nuclease from Aspergillus oryzae and by BAL-31 nuclease from Alteromonas espejiana BAL-31. The single-strand regions or local denaturation regions do not seem to be related to or caused by DNA superhelical conformational changes since they were detected at drug concentrations at which no significant DNA superhelical turns were found. DNA shortening, superhelical conformational changes, and local denaturation regions can be explained by the previously proposed "DNA intrastrand cross-linking" model (Stone et al., J. Mol. Biol., 104: 793-801, 1976).

Cisplatin↗
PubMed1980

Interactions of a new antitumor antibiotic BBM-928A with deoxyribonucleic acid. Bifunctional intercalative binding studied by fluorometry and viscometry.

A new actinoleukin-like antitumor antibiotic, BBM-928A, has been shown to interact with isolated DNA molecules. BBM-928A contains two substituted quinolines linked by a cyclic decapeptide. Quenching effects of the covalently closed superhelical PM2 DNA on the BBM-928A fluorescence revealed a strong interaction with an apparent association constant of 1.93 x 10(7) M-1 and with 11 deoxyribonucleic acid (DNA) nucleotides per BBM-928A binding site. Viscometric studies indicated the BBM-928A induced an unwinding-rewinding process of the closed superhelical PM2 DNA typically observed for DNA intercalators. The unwinding angle (43 degrees) induced by BBM-928A was almost twice that of the ethidium bromide (26 degrees), a monofunctional intercalator. The BBM-928A-induced increase of the helix length of sonicated rodlike calf thymus DNA was approximately 1.5-fold that induced by the ethidium bromide. On the basis of these observations, we concluded that BBM-928A bifunctionally intercalated with DNA in a manner similar to the bifunctional intercalation of echinomycin.

Antibiotics, Antineoplastic↗
PubMed1980

Comparative nuclear and cellular incorporation of daunorubicin, doxorubicin, carminomycin, marcellomycin, aclacinomycin A and AD 32 in daunorubicin-sensitive and -resistant Ehrlich ascites in vitro.

The kinetics of cellular and nuclear incorporation of a number of new anthracyclines into daunorubicin-sensitive and -resistant Ehrlich ascites cells were determined in vitro. For comparative quantitative analyses the substances were extracted with a 0.3 N HCl/50% ethanol (v/v) solution from either whole cells or purified citric acid nuclei after various intervals of in vitro incubation. At steady state the intracellular and intranuclear concentrations of daunorubicin and doxorubicin were reduced by about 50% in the resistant cell line. Marcellomycin and carminomycin concentrations were only reduced by 9% and 11%, respectively, and no differences between sensitive and resistant cells were seen in the case of aclacinomycin A and AD 32. When the ratios of nuclear to cellular drug were determined at steady state lowest value was found for AD 32 (0.26). In contrast, aclacinomycin A and carminomycin were mainly (78% and 74%) and marcellomycin almost exclusively (95%) concentrated in the nucleus. When the total amounts of drug incorporated per cell were compared, the highest values were measured for aclacinomycin A and the lowest for AD 32 both in the sensitive and the resistant tumor. Additional determinations of the 50% inhibitory concentrations for thymidine uptake showed similar differences between these anthracyclines which were not related to the potency of the drugs in vivo. It is concluded that apart from nuclear incorporation and inhibition of DNA synthesis other factors may be decisive for anthracycline-induced cytotoxicity.

Aclarubicin↗
PubMed1980

Effects of several anthracycline antitumor antibiotics on the transcriptional activity of isolated nucleoli.

The class II anthracycline antitumor antibiotics musettamycin, rudolfomycin, aclacinomycin and marcellomycin, which were shown in earlier studies to preferentially inhibit the synthesis of nucleolar RNA in intact tumor cells, were studied in an isolated nucleolar transcriptional assay. Their effects were compared with those of the nucleolar non-selective anthracyclines adriamycin, carminomycin and pyrromycin, as well as with the 10-descarbomethoxy-analogs of marcellomycin and rudolfomycin. The isolated nucleolar transcriptional assay was found to have linear activity for 30 minutes at 30 degrees C. At increasing concentrations of alpha-amanatin up to 200 micrograms/ml, the maximum degree of inhibition of transcriptional activity was found to be 6 approximately 7%. The ranking of nucleolar RNA synthesis inhibitory potencies of the class I and II anthracyclines and the 10-descarbomethoxy-analogs obtained previously in intact cells was reproduced in the isolated nucleoli assay system described here. Thus, evidence for the use of this assay as a screen for nucleolar active antitumor agents is presented.

Animals↗
PubMed1980

Comparison of DNA damage and single- and double-strand breakage activities on PM-2 DNA by talisomycin and bleomycin analogs.

Single- and double-strand breakage of isolated PM-2 DNA by structural analogs of the glycopeptide antitumor antibiotics bleomycin (BLM) and talisomycin (TLM) was investigated. Breakage of PM-2 DNA was determined by two systems: an ethidium bromide fluorescence assay; and agarose gel electrophoresis. The fluorescence assay, which measures total breakage of DNA including single- and double-strand breakage and alkaline labile damage, showed that the BLM's, A2 and B2 induced more total DNA breakage than did the TLM's A, B, S2b, and S10b. As measured by the comparison of the concentration of analog required to cause 50% breakage of superhelical DNA, BLM's A2 and B2 were 10 times more active than TLM's S2b and S10b and 25 times more active than TLM's A and B. Gel electrophoresis, which measures the extent of both single- and double-strand breakage of DNA, showed that at equivalent levels of breakage of superhelical DNA each of the TLM's caused more double-strand breakage of DNA than did the BLM's. Thus, the structural alterations near the bithiazole in the TLM's, which distinguish them structurally from the BLM's, result in a reduction of the total PM-2 DNA breakage activity and enhanced production of double-strand breaks relative to single-strand breaks by TLM when compared to BLM.

Bacteriophages↗
PubMed1980

Interaction of cis-diamminedichloroplatinum(II) with PM-2 DNA.

The interaction of cis-diamminedichloroplatinum(II) (CDDP) with PM-2 DNA was studied using two techniques: (a) agarose gel electrophoresis of PM-2 DNA conformation isomers after CDDP binding; and (b) viscometric measurement of different forms of CDDP-bound PM-2 DNA. In both systems, the results indicated that the DNA isomers interacted differently with CDDP. CDDP induced a decrease of viscosity upon interacting with single-strand broken relaxed circular (Form II) and double-strand broken linear (Form III) PM-2 DNA's. These observations are consistent with a "DNA shortening effect" proposed by Cohen et al. [Science (Wash. D. C.), 203: 1014-1016, 1979] and Macquet et al. [Biochimie (Paris), 60: 901-914, 1978] When covalently closed circular (Form I) PM-2 DNA was used, increasing concentrations of CDDP induced an initial slight increase and then decrease of electrophoretic mobility to the degree that it comigrated with CDDP-bound Form II DNA. Further addition of CDDP restored the electrophoretic mobility of Form I DNA. Corresponding changes in the viscosity of CDDP-bound Form I DNA showed an initial decrease, then an increase, and a final prolonged decrease of viscosity. These effects are similar but not identical to those induced by either DNA intercalators (e.g., ethidium bromide) or certain DNA denaturating agents (e.g., formaldehyde, ultraviolet light, alkali trichloroacetate, methylmercuric hydroxide, and carbodiimide). Thus, CDP may induce a DNA superhelix-unwinding process followed either by rewinding or a denaturation process or both. Quantitative analysis of the agarose gel electrophoretic pattern plus sucrose density gradient centrifugation studies also indicated that there was little DNA strand breakage induced by CDDP treatment.

Animals↗