Profiling of ecdysteroids in complex biological samples using liquid chromatography/ion trap mass spectrometry

A sensitive method using high-performance liquid chromatography coupled to a mass spectrometer with electrospray ionization source (HPLC/ESI-MS) was developed for detection of ecdysteroids in biological samples. We report here for the first time that ecdysteroids can be classified into three groups based on ESI full-scan mass spectra: group 1 (ecdysone (E), 2-deoxyecdysone (2dE), 2,22-dideoxyecdysone (3beta5beta-KT), and 3alpha5alpha[H]-dihydroxycholest-7-en-6-one (3alpha5alpha-KD)), in which loss of one molecule of water from the protonated molecular ion ([M+H](+)) represents the dominant ion; group 2 (20-hydroxyecdysone (20E), makisterone A (MakA), 3beta5beta-KD, and 3beta5alpha-KD), in which [M+H](+) is a major ion but some water loss is observed; and group 3 (muristerone A (MurA) and ponasterone A (PonA)), in which [M+H](+) is the dominant ion with no water loss observed. Based on the analytical procedure in combination with structural information from the group classification and with the application of source-induced dissociation, we identified free ecdysteroids in biological samples: 20,26-dihydroxyecdysone and ecdysonic acid in the larval hemolymph, and the progressive metabolism of 26-hydroxyecdysone (26E) to 3alpha-26E from day-1 to day-3 embryos of the tobacco hornworm Manduca sexta.

Allogeneic bone marrow transplantation for juvenile myelomonocytic leukemia: a single center experience of 23 patients

Juvenile myelomonocytic leukemia (JMML) is a childhood leukemia for which allogeneic BMT is the only curative therapy. At our pediatric stem cell transplantation unit, we performed 26 BMTs in 23 children (age 0.5–12.7 years). Conditioning was CY/TBI based (1980–1996, n=14) or BU/CY/melphalan based (1996–2001, n=9). Donors were HLA-identical siblings (n=11), unrelated volunteers (n=9) or mismatched family members (n=3). A total of 10 patients survive in CR (median follow-up 6.8 years, range 3.1–22.2 years). Relapse or persistent disease was observed in eight and two patients, respectively. Nine of these patients died, one achieved a second remission following acute nonlymphatic leukemia chemotherapy (duration to date 5.3 years). Transplant-related mortality occurred in four patients. Overall survival at 5 and 10 years was 43.5%. Using T-cell-depleted, one-antigen mismatched unrelated donors was the only significant adverse factor associated with relapse in multivariate analysis (P=0.039, hazard ratio 4.9). Together with a trend towards less relapse in patients with graft-versus-host-disease and in patients transplanted with matched unrelated donors, this suggests a graft-versus-leukemia effect of allogeneic BMT in JMML.

Intravenous busulfan in children prior to stem cell transplantation: study of pharmacokinetics in association with early clinical outcome and toxicity

We studied the pharmacokinetics of intravenous busulfan (Bu) in children in order to further optimize intravenous Bu dosing in relation to toxicity and survival. A total of 31 children undergoing Bu-based conditioning for allogeneic SCT were enrolled in a study. The starting dose was 1.0 mg/kg (age < 4 years) and 0.8 mg/kg (age > or =4 years), four doses per day during 4 days. Dose adjustment was allowed up to a maximum dose of 1.0 mg/kg per dose if the target area under the serum concentration-time curve (AUC) was not reached. Pharmacokinetic studies were performed after the first dose. Donor engraftment was established in 28 out of 31 patients. The average AUC after the first dose was the same in children < 4 years as in children > or =4 years. Mean clearance was higher in children < 4 years than in children > or =4 years. In 35% of all patients, total AUC was within the target AUC. The other children's AUCs were below the target range. No relationships were found between systemic exposure to Bu and toxicity or clinical outcome. We concluded that, in accordance with previous data, within the observed AUCs no clear relationship was observed between Bu AUC and outcome with respect to toxicity, engraftment and relapse.

Stable-isotope probing of bacteria capable of degrading salicylate, naphthalene, or phenanthrene in a bioreactor treating contaminated soil

[13C6]salicylate, [U-13C]naphthalene, and [U-13C]phenanthrene were synthesized and separately added to slurry from a bench-scale, aerobic bioreactor used to treat soil contaminated with polycyclic aromatic hydrocarbons. Incubations were performed for either 2 days (salicylate, naphthalene) or 7 days (naphthalene, phenanthrene). Total DNA was extracted from the incubations, the "heavy" and "light" DNA were separated, and the bacterial populations associated with the heavy fractions were examined by denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone libraries. Unlabeled DNA from Escherichia coli K-12 was added to each sample as an internal indicator of separation efficiency. While E. coli was not detected in most analyses of heavy DNA, a low number of E. coli sequences was recovered in the clone libraries associated with the heavy DNA fraction of [13C]phenanthrene incubations. The number of E. coli clones recovered proved useful in determining the relative amount of light DNA contamination of the heavy fraction in that sample. Salicylate- and naphthalene-degrading communities displayed similar DGGE profiles and their clone libraries were composed primarily of sequences belonging to the Pseudomonas and Ralstonia genera. In contrast, heavy DNA from the phenanthrene incubations displayed a markedly different DGGE profile and was composed primarily of sequences related to the Acidovorax genus. There was little difference in the DGGE profiles and types of sequences recovered from 2- and 7-day incubations with naphthalene, so secondary utilization of the 13C during the incubation did not appear to be an issue in this experiment.

Graft dysfunction and delayed immune reconstitution following haploidentical peripheral blood hematopoietic stem cell transplantation

For many children with life-threatening hematological diseases, hematopoietic stem cell transplantation (HSCT) is the only curative option. In children lacking a matched related or unrelated donor and with the certainty that, left untreated, death will ensue alternative donors must be sought. Haplo-identical peripheral blood stem cell transplantation (PBSCT) from a healthy parent is a feasible alternative. To reduce the risk of fatal graft-versus-host disease (GvHD) as a complication of transplant across major histocompatibility antigens, intense T-cell depletion is required. Large numbers of purified, cytokine mobilized peripheral stem cells (the so-called mega-dose concept) are required to compensate for the significantly increased risk of either graft failure or early rejection. In our unit, despite this approach, graft dysfunction has, in a significant group of children, proved problematic and, despite salvage attempts at re-transplantation, usually fatal. In children with hematological malignant disease, our overall relapse-free survival is 41%. However, successful transplant outcome has been associated with considerable delays in immune reconstitution that can be implicated in subsequent viral reactivation. We are investigating new strategies to improve the outcome of haplo-identical PBSCT, which may allow us to offer this form of treatment to more children requiring urgent HSCT.

1,N2-propanodeoxyguanosine adducts of the 1,3-butadiene metabolite, hydroxymethylvinyl ketone

1,3-Butadiene (BD) is a rodent and human carcinogen. While several epoxides formed during BD metabolism are mutagenic and may contribute to BD carcinogenicity, another proposed metabolite, hydroxymethylvinyl ketone (HMVK), could also be involved. A significant quantity of HMVK is likely to be formed since it is a proposed intermediate in the metabolism of 3-butene-1,2-diol (BD-diol) to 1,2-dihydroxy-4-(N-acetylcysteinyl)butane, the major mercapturic acid metabolite of BD in humans. In addition, BD-diol is a major BD metabolite in liver perfusion experiments in rodents. By analogy with other alpha,beta-unsaturated carbonyls, HMVK is likely to be mutagenic via formation of promutagenic 1,N(2)-propanodeoxyguanosine adducts. The objective of the current study was to investigate the formation of such adducts in vitro. The reaction between HMVK and dGuo yielded two major products shown to be identical by positive ion electrospray-MS, having protonated molecular ions with m/z consistent with HMVK-derived 1,N(2)-propanodeoxyguanosine (HMVK-dGuo). Rechromatography of each fraction yielded two fractions with retention times identical to those initially isolated, suggesting equilibration between two diastereomers. Two partially resolved sets of (1)H NMR signals were consistent with a 1:1 mixture of diastereomeric C-6-substituted adducts equilibrating slowly on an NMR time-scale. Following deglycosylation, C-6 substitution was verified by two-dimensional correlation NMR spectroscopy, indicating that the initial adducts were formed by Michael addition of dGuo-N1 to the terminal vinyl carbon followed by cyclization to the 1,N(2)-propano structure. Reactions with calf thymus DNA under physiological conditions yielded two sets of products. The first set had HPLC retention times and mass spectra identical to those of the previously characterized C-6-substituted HMVK-dGuo diastereomers. The second set had a molecular ion and fragmentation pattern identical to the C-6-substituted adducts and on this basis were assigned as the diastereomeric C-8 adducts. In addition to detecting HMVK-dGuo in treated DNA, the adducts were also present in control DNA. Overall, our research demonstrates that HMVK can form promutagenic DNA adducts and it therefore has the potential to play a role in BD-associated mutagenicity.

‘Candidatus Mycoplasma haematoparvum’, a novel small haemotropic mycoplasma from a dog

A novel small haemoplasma was detected following cytological examination of blood smears from a splenectomized dog with haemic neoplasia. The 16S rRNA and rnpB genes of the organism were partially sequenced and a phylogenetic tree constructed. The organism was most closely related to the small feline haemoplasma, ‘Candidatus Mycoplasma haemominutum’ (94 % 16S rRNA gene nucleotide sequence identity; 75 % rnpB) and was only distantly related to Mycoplasma haemocanis (78 % 16S rRNA gene nucleotide sequence identity; 65 % rnpB). As this organism has not been cultured in vitro, the candidate species name ‘Candidatus Mycoplasma haematoparvum’ is proposed.

Analysis of M1G-dR in DNA by Aldehyde Reactive Probe Labeling and Liquid Chromatography Tandem Mass Spectrometry

A novel method for the measurement of pyrimido[1,2-a]purin-10(3H)one (M1G) has been developed. Previous methods for analysis of M1G have been confounded by the fact that this lesion exists in equilibrium between a ring-closed form and a ring-opened aldehyde form. Poor detection sensitivity of the aldehydic form can result from loss of the adduct during analysis by its reaction with amines or proteins. We utilized the aldehyde reactive probe (ARP) to produce a stable ARP-M1G-deoxyribose (ARP-M1G-dR) conjugate to minimize adduct loss. This conjugate has increased the hydrophobicity that enhances separation of ARP-M1G-dR from unmodified DNA nucleosides by using solid phase extraction. In addition, measuring ARP-M1G-dR by selective reaction monitoring (SRM) of the [ARP-M1G-dR + H]+ (635) --> [M1G + H]+ (188) transition increases the detection sensitivity by nearly an order of magnitude relative to the measurement of M1G-dR by SRM. For accurate measurement, analytical standard (AS) DNA and internal standard (IS) DNA were used. High purity 15N-labeled DNA was isolated from Escherichia coli that had been grown in minimum salt medium containing (15NH4)2SO4. The 15N-DNA and calf thymus DNA were treated with malondialdehyde to induce a high number of M1G adducts to prepare the IS and AS DNA, respectively. A consistent calibration curve was established from the analysis of 200 microg of blank DNA, 23 ng of IS DNA (400 fmol of 15N5-M1G-dR), and AS DNA containing 0-810 fmol of M1G-dR. With the use of this novel IS DNA and selective labeling, this assay is a useful tool for monitoring oxidative stress-induced DNA damage from small amounts of DNA without the need of a specific antibody or laborious procedures. By this assay, two M1G adducts/10(8) guanines can readily be detected. Furthermore, this approach should be applicable to the analysis of other aldehydic DNA adducts as well as the measurement of an array of DNA lesions.

Synthesis of chlorinated and non-chlorinated biphenyl-2,3- and 3,4-catechols and their [2H3]-isotopomers

A synthetic scheme is described for chlorinated biphenyl-2,3- and 3,4-catechols to be used as standards for structural assignment of metabolites and protein adducts of 2,2',5,5'-tetrachlorobiphenyl in which both rings retain chlorine substituents. The scheme has general applicability to the synthesis of chlorinated biphenyl catechols. Dimethyl catechol ethers are coupled to dichloroaniline via the Cadogan reaction to give a library of isomers, followed by demethylation of the ethers with BBr3 to yield the target catechols. Separation of pure isomers is accomplished by TLC or HPLC prior to or following demethylation, depending on the isomer mixture. [2H3]-Isotopomers are generated using 2,5-dichloroaniline-d3 as the starting arylamine in the coupling reaction. The dichloroaniline-d3 hydrochloride is obtained as the sole product from nitration of p-dichlorobenzene-d4 followed by Pd/C-catalyzed hydrogenation under strongly acidic conditions. This hydrogenation procedure provides a simple and convenient approach to selective reduction of aryl nitro groups in the presence of halogen ring substituents.

Identification of a novel hemotropic mycoplasma in a splenectomized dog with hemic neoplasia

A 3-year-old sexually intact male Bull Mastiff underwent splenectomy for splenic thrombosis; prior to and after splenectomy, multiple blood transfusions were administered. Two weeks after the procedure, T-cell lymphoproliferative disease was diagnosed. Treatment with prednisone and chlorambucil was initiated, and 2 weeks later, cytologic examination of a blood smear revealed small (0.3 microm), coccoid basophilic bodies on the surface of approximately 70% of the RBCs. Morphologically, these resembled "Candidatus Mycoplasma haemominutum." A polymerase chain reaction assay was used to amplify a partial 16S rRNA sequence in blood obtained from the dog; the product was sequenced and compared with 16S rRNA gene sequences of other hemotropic mycoplasmas. The sequence was 98% homologous to that of "Candidatus M haemominutum", but only 77% homologous to that of M haemocanis and M haemofelis.

Significance of amplified fragment length polymorphism in identification and epidemiological examination of Candida species colonization in children undergoing allogeneic stem cell transplantation

Candida albicans and non-C. albicans Candida species are increasingly being isolated from patients in high-risk categories, most notably, those who have undergone stem cell transplantation (SCT). Identification of the presence of non-C. albicans Candida species early in the course of the transplant procedure is important, as these species exhibit different sensitivities to the available antifungal treatments and cause mortality at rates that vary from those for C. albicans. Amplified fragment length polymorphism (AFLP) analysis has been shown to be a reliable method of reproducibly identifying medically important Candida species. We investigated the use of serial AFLP analysis of 54 routine surveillance cultures for the identification and epidemiological examination of Candida sp. colonization in five consecutive children undergoing allogeneic SCT. One child became colonized with a C. albicans strain and remained colonized with this strain during the whole admission period. Another child had persistent colonization with a C. albicans strain with striking variations in its AFLP patterns over time, which was considered indicative of microevolution. Candida dubliniensis, Candida lusitaniae, and Saccharomyces cerevisiae were identified in the three remaining patients, with two children being simultaneously and transiently colonized with different species. These findings show that colonization with yeasts during transplantation is a complex and dynamic interaction between the host and the organism(s). In our study three strains from eight separate time points were incorrectly identified as C. albicans by a rapid enzyme test. AFLP analysis of surveillance cultures allowed more accurate and informative epidemiological evaluations of pathogenic yeasts in children during transplantation.

[Three children with general malaise, fever, weight loss and cervical lymphadenopathy]

Combinations of symptoms such as general malaise, fever, weight loss and cervical lymphadenopathy have extensive differential diagnoses. In three children, girls aged 11, 13 and 17 years who presented with these symptoms, three different diagnoses were obtained. The first had Hodgkin's disease, the second mixed connective tissue disease (MCTD), and the third Hodgkin's disease in combination with systemic lupus erythematosus (SLE). A systematic approach is necessary for the diagnosis of such conditions. Careful history taking can provide valuable information while a physical examination provides essential clues for the final diagnosis. In particular, nail-fold lesions, tendon nodules and signs of myopathy should be looked for in patients suspected of MCTD and/or SLE. In Hodgkin's disease, generalized or localised lymphadenopathy combined with a short history of extreme fatigue are the most important. Additional investigations should be individualized in order to minimise the diagnostic delay and make possible early treatment.

Paediatric allogeneic bone marrow transplantation for homozygous beta-thalassaemia, the Dutch experience

We reviewed the results of the Dutch paediatric bone marrow transplant (BMT) program for children receiving HLA-identical BMT for beta-thalassaemia major over an 18-year period. In all, 19 patients underwent a total of 21 transplants in our treatment centre between July 1984 and February 2002. Eight females (age 0.3-12 years; median 5 years) and 11 males (age 0.8-18 years; median 6 years) were included. Information, prospectively collected, included molecular defects, donor genotype, beta/alpha-globin expression rates, serum ferritin levels, hepato-splenomegaly, chelation history, virology screening, liver pathology together with post-transplant outcome inclusive of leucocyte chimerism. In total, 11 patients received standard busulphan/cyclophosphamide (Bu/Cy) conditioning, with or without ATG. Stable engraftment was seen in 5/11 with late rejection occurring in six patients. Of these, two children underwent a second successful SCT. For this group, overall event-free survival (EFS) and disease-free survival (DFS) were 90 (10/11) and 64% (7/11), respectively. The probability of rejection was 55%. Subsequent addition of melphalan to the conditioning regimen resulted in long-term stable engraftment in all patients with an EFS/DFS for this group of 90% (9/10). Treatment-related mortality, irrespective of conditioning, was low at 5% (1/19 patients). Veno-occlusive disease (VOD) occurred in 19% (4/21 transplants) and acute GvHD in 19% (4/21 transplants). Post-BMT beta/alpha synthetic ratio measurement monitored donor erythroid engraftment and predicted rejection with a return to transfusion dependency. Maintained full donor chimerism is indicative of stable engraftment both for leucocyte and erythroid lineages, whereas mixed donor chimerism is not. Our results emphasise the importance of the conditioning regimen and post-transplant chimerism surveillance predictive of rejection or long-term stable engraftment.

Synthesis and characterization of peptides containing a cyclic Val adduct of diepoxybutane, a possible biomarker of human exposure to butadiene

1,3-Butadiene, a potential human carcinogen widely used in industry, is oxidized by cytochrome P450 to diepoxybutane (DEB), which is the most mutagenic of the known butadiene metabolites. Assessment of the toxicological significance of DEB formation in humans and animals requires identification of a biomarker uniquely associated with DEB for use in molecular dosimetry studies. We wished to develop a specific and sensitive assay for one such suitable marker, the cyclic adduct 2-(3,4-dihydroxypyrrolidin-1-yl)-3-methylbutyramide (pyr-V), which is formed from addition of DEB to the terminal Val of the alpha- and beta-chains of hemoglobin. We needed to prepare a pure, rigorously characterized DEB-modified N-terminal oligopeptide for raising antibodies both to use in an immunoaffinity purification step and to standardize the assay. In addition, we needed a pure isotopomer to serve as an internal standard for quantitation by LC-MS. Direct modification of the globin sequences by reaction with DEB in vitro proved to be unproductive. We therefore opted to synthesize the cyclic Val adduct and incorporate it by FMOC chemistry into the appropriate oligopeptide sequences. In vitro and in vivo, butadiene is oxidized to enantiomeric and meso forms of DEB. A priori, all three DEB isomers are expected to form pyr-V adducts, resulting in three diastereomeric N-terminal peptides. We therefore synthesized a mixture of the cyclic Val diastereomers as their methyl esters by reaction of DEB with l-Val methyl ester hydrochloride. After protection as the di-O-tert-butyl derivatives, the mixture of 2-(3,4-di-t-butoxypyrrolidin-1-yl)-3-methylbutyric acid diastereomers was incorporated as the N-terminal residue into the 1-11 human globin alpha-chain sequence VLSPADKTNVK. The presence of the three diastereomers was confirmed by two-dimensional correlation NMR spectroscopy and temperature-dependent (1)H NMR. This strategy enabled us to obtain pure, rigorously characterized haptens in quantity for the preparation of polyclonal antibodies. Use of FMOC-protected (2)H(3)-Leu in the automated oligopeptide synthesis provided the required isotopomers for use as internal standard.

Reconciling animal and human data in a cancer risk assessment of acrylonitrile

OBJECTIVES

Bioassays of rats exposed to acrylonitrile have consistently detected an elevated incidence of central nervous system (CNS) cancer. In contrast, epidemiologic studies have not found a statistically stable increase in CNS cancer mortality. The purpose of this paper is to examine whether or not CNS cancers predicted from the most appropriate inhalation bioassay in rats are consistent with CNS cancers observed in 3 recent, large epidemiologic studies.

METHODS

A linearized multistage model was fit to dose-response data from a rat inhalation bioassay to estimate carcinogenic potency. This potency was applied to epidemiologic studies of acrylonitrile-exposed workers. After adjustment for less than complete lifetime follow-up in the epidemiologic studies, consistency was examined between CNS cancers predicted by the model fit to the animal data for the exposure levels and sample sizes of the epidemiologicy studies and the CNS cancers observed in the epidemiologic studies.

RESULTS

The model predicted totals of 17.7, 3.6, and 7.6 CNS cancer deaths for the studies. These predictions were not far from the observed CNS cancer deaths (12, 6, and 6) and were well within their 95% confidence intervals of 6.9-22.3, 2.2-13.1, and 2.2-13.1, respectively.

CONCLUSIONS

The CNS cancer potency estimated from the best available inhalation bioassay was consistent with the observed deaths in the epidemiologic studies as long as continuous lifetime exposure was chosen as the exposure metric. The lack of observed excess in CNS cancer among the studied workers may have been due to low exposures, insufficient follow-up times, or both.

Mutagenicity in lung of big Blue((R)) mice and induction of tandem-base substitutions in Salmonella by the air pollutant peroxyacetyl nitrate (PAN): predicted formation of intrastrand cross-links

Peroxyacetyl nitrate (PAN) is a ubiquitous air pollutant formed from NO(2) reacting with acetoxy radicals generated from ambient aldehydes in the presence of sunlight and ozone. It contributes to eye irritation associated with photochemical smog and is present in most urban air. PAN was generated in a chamber containing open petri dishes of Salmonella TA100 (gas-phase exposure). After subtraction of the background mutation spectrum, the spectrum of PAN-induced mutants selected at 3.1-fold above the background mutant yield was 59% GC-->TA, 29% GC-->AT, 2% GC-->CG, and 10% multiple mutations - primarily GG-->TT tandem-base substitutions. Using computational molecular modeling methods, a mechanism was developed for producing this unusual tandem-base substitution. The mechanism depends on the protonation of PAN near the polyanionic DNA to release NO(2)(+) resulting in intrastrand dimer formation. Insertion of AA opposite the dimerized GG would account for the tandem GG-->TT transversions. Nose-only exposure of Big Blue((R)) mice to PAN at 78ppm (near the MTD) was mutagenic at the lacI gene in the lung (mutant frequency +/-S.E. of 6.16+/-0.58/10(5) for controls versus 8.24+/-0.30/10(5) for PAN, P=0.016). No tandem-base mutations were detected among the 40 lacI mutants sequenced. Dosimetry with 3H-PAN showed that 24h after exposure, 3.9% of the radiolabel was in the nasal tissue, and only 0.3% was in the lung. However, based on the molecular modeling considerations, the labeled portion of the molecule would not have been expected to have been bound covalently to DNA. Our results indicate that PAN is weakly mutagenic in the lungs of mice and in Salmonella and that PAN produces a unique signature mutation (a tandem GG-->TT transversion) in Salmonella that is likely due to a GG intrastrand cross-link. Thus, PAN may pose a mutagenic and possible carcinogenic risk to humans, especially at the high concentrations at which it is present in some urban environments.

N-porphyrinylamino and -amido compounds by addition of an amino or amido nitrogen to a porphyrin meso position

This report describes the synthesis and characterization of a series of octaethylporphyrin derivatives in which the porphyrin pi-network is connected to phenyl, 3-fluoranthenyl, or 1-pyrenyl aromatic systems through a meso amino or amido nitrogen. Metal-free bases and zinc(II) and iron(III) complexes have been obtained. These compounds represent the first examples of linkages between porphyrins and extended pi-networks through a nitrogen atom directly attached to a porphyrin meso position. 1H NMR studies of the metal-free bases and zinc complexes showed that in the amido-linked adducts, the plane containing the aryl substituent was oriented perpendicular to the plane of the porphyrin. Linkage through the secondary amino nitrogen, however, allowed the aryl plane to rotate toward coplanarity with the porphyrin plane, resulting in conjugation of the highest occupied aryl and porphyrin molecular orbitals through the nitrogen lone pair. In developing routes to the amino-linked compounds, the facile formation of fused azaaryl chlorins via an oxidative intramolecular cycloaddition was observed. An aryl carbon ortho to the meso linkage attacked the beta-carbon of an adjacent pyrrole ring, accompanied by 1,2-migration of a pyrrole beta-ethyl substituent and a two-electron oxidation of the initially formed macrocycle. The resulting structures are analogous to benzochlorins. The electronic spectra of the metal-free bases are characterized by intense, long-wavelength bands in the visible region. Molecular structures of the chloroferric complexes of the azabenzofluorantheno- and azabenzpyrenoporphyrin macrocycles (derived from fusion of the fluoranthenyl and pyrenyl substituents, respectively) were obtained by X-ray diffraction. The porphyrin moiety in the azabenzofluoranthenoporphyrin adopted a gable structure, with a 22 degrees fold along a diagonal including the pyrrole-ring C4 and C16 alpha-carbons. By contrast, the azabenzpyrenoporphyrin was virtually planar.

The contribution of benzene to smoking-induced leukemia

Cigarette smoking is associated with an increased risk of leukemia; benzene, an established leukemogen, is present in cigarette smoke. By combining epidemiologic data on the health effects of smoking with risk assessment techniques for low-dose extrapolation, we assessed the proportion of smoking-induced total leukemia and acute myeloid leukemia (AML) attributable to the benzene in cigarette smoke. We fit both linear and quadratic models to data from two benzene-exposed occupational cohorts to estimate the leukemogenic potency of benzene. Using multiple-decrement life tables, we calculated lifetime risks of total leukemia and AML deaths for never, light, and heavy smokers. We repeated these calculations, removing the effect of benzene in cigarettes based on the estimated potencies. From these life tables we determined smoking-attributable risks and benzene-attributable risks. The ratio of the latter to the former constitutes the proportion of smoking-induced cases attributable to benzene. Based on linear potency models, the benzene in cigarette smoke contributed from 8 to 48% of smoking-induced total leukemia deaths [95% upper confidence limit (UCL), 20-66%], and from 12 to 58% of smoking-induced AML deaths (95% UCL, 19-121%). The inclusion of a quadratic term yielded results that were comparable; however, potency models with only quadratic terms resulted in much lower attributable fractions--all < 1%. Thus, benzene is estimated to be responsible for approximately one-tenth to one-half of smoking-induced total leukemia mortality and up to three-fifths of smoking-related AML mortality. In contrast to theoretical arguments that linear models substantially overestimate low-dose risk, linear extrapolations from empirical data over a dose range of 10- to 100-fold resulted in plausible predictions.

Apoptosis corrected proliferation fraction in childhood ALL is related to karyotype

BACKGROUND

Tumour doubling time, a parameter in drug sensitivity testing, reflects both cell proliferation and apoptosis. Variable apoptosis fractions may explain the poor correlation of S-fraction and drug response. DNA aneuploidy (reflecting intrinsic DNA instability) may, by increasing apoptosis, affect drug response.

AIM

To assess the relationship between apoptosis corrected proliferation fraction and DNA ploidy in childhood acute lymphoblastic leukemia (ALL).

METHODS

1.3.1. Study Groups. Thirty two consecutive, unselected diagnostic cases of childhood ALL were included in the study. 1.3.2. Karyotype. A normal karyotype was found in 15 cases (7M, 8F, age 8 m-12 yrs); high hyperdiploid aneuploidy (DNA index > 1.5) was found in 7 patients (1M, 7F, age 3-12 yrs) whereas complex karyotypic anomalies, but with 2n or near 2n DNA were present in 10 patients (7M, 3F, age 1 y 7 m -16 yrs). 1.3.3. Proliferation Fraction Assessment. Immunocytochemical demonstration of S-phase associated nuclear expression of the Ki-67 antigen (MM1, NovaCastra, UK). 1.3.4. Apoptosis Fraction Assessment. Binding of a horse radish peroxidase labelled DNA probe for the 3'-OH ends of apoptosis derived Klenow fragments (Frag-EL, CalBiochem, USA). 1.3.5. Quantitation. Computer assisted image analysis (Quantimet 570C), of 10 systematically random fields of a minimum of 20 nuclei each. A nuclear size bias correcting counting frame and rule were used to correct for cell proliferation associated nuclear volume increase and for the expected nuclear volume reduction resulting from apoptosis.

RESULTS

Corrected for apoptosis, proliferation fraction was highest (mean 57.5%, range 1-100) in poor prognosis, complex karyotype anomalies. Good prognosis, high hyper diploidy showed significantly lower proliferation rates (mean 24.7%, range 12-40) (p < 0.01, t-test).

CONCLUSION

Apoptosis corrected cell proliferation rate in childhood ALL is not independent of karyotype abnormality which may partly explain a relation to therapy response and prognosis.

Proliferation and apoptosis does not affect presenting white cell count in childhood ALL

BACKGROUND

Treatment response/drug resistance in childhood acute lymphoblastic leukaemia (ALL) is related to presenting white cell count. This relationship might be explained by high proliferation fraction or by absence of significant apoptosis, but is presently unknown.

AIMS

To study the relationship between proliferation and apoptosis in childhood ALL.

METHODS

1.3.1. Study Groups. Thirty consecutive, unselected cases of childhood ALL (15M,15F). White cell count varied from 1-200 at presentation. 1.3.2. Proliferation/Apoptosis Fraction. Immunocytochemical detection of Ki-67 (MM1, NovaCastra, UK) on 5 microns paraffin slides, Immunocytochemical detection of apoptosis specific DNA (Klenow) fragments by labelling of 3'-OH ends in 10 microns paraffin sections (Frag-EL, CalBiochem, USA). 1.3.3. Quantitation. Image analysis (Quantimet 570C) using nuclear size bias correcting counting frame and rule. Calculation of proliferation (%Ki-67) fraction and of apoptosis corrected proliferation fraction (%Ki-67/100-%apoptosis).

RESULTS

Using both linear, logarithmic regression as well as power analysis, no relationship between variables was detected.

CONCLUSION

Presenting white cell count is not related to apoptotic or cell proliferative activity or to net tumour growth defined by the balance between these two processes. The relationship to treatment resistance still requires explanation.

Demonstration of differences in drug resistance by direct testing of DNA excision repair activity following standard and liposomal daunorubicin exposure in normal paediatric marrow using high resolution CLSM

BACKGROUND

High resolution Confocal Laser Scanning Microscopy (CLSM) may be applied to testing of drug resistance in vitro in clinical setting. Rapid analysis of DNA damage by precise quantitation of excised DNA in bone marrow samples exposed to potential treatment moieties directly after isolation but the relative sensitivity of the integrated method is as yet untested.

AIMS

To test the clinical applicability of SCGE/high resolution CLSM for differences in drug resistance in marrow cells.

METHODS

Cells from normal bone marrow samples were exposed for identical periods and at 4 concentrations to either 1 hour of standard Daunorubicin (.5, 1, 1.5, 2 micrograms/ml) or 8 hours DaunoXome (courtesy of NeXstar Inc, USA) (.05, .1, .15, .2 microgram/ml). After 2 and 6 hours recovery, cells were harvested for SCGE, randomization, analysis of tail length, total excised DNA and fragment size distribution using high resolution CLSM.

RESULTS

Tail length and fragment size distribution was not, but total excised DNA was significantly increased after 0.1 microgram/ml Liposomal Daunorubicin (DaunoXome) compared to 1.0 microgram/ml Daunorubicin.

CONCLUSION

SCGE/high resolution CLSM effectively demonstrated differences in Daunorubicin resistance of human marrow cells to alternative formulations. The method has potential for use in clinical testing of neoplastic cell drug resistance.

Differential kinetics of drug resistance in human leukaemic cells measured by SCGE/CLSM

BACKGROUND

New analogues of DNA directed chemotherapy moieties are available for comparative efficacy testing in human neoplastic disease. In addition to MTT testing direct assessment of DNA excision repair activity after direct exposure of marrow cells may provide information on relative DNA effects in vitro.

AIMS

To assess the ability of SCGE/high resolution CLSM to detect differences in drug resistance between human neoplastic cell lines in the DNA excision repair response to chemotherapy.

METHODS

Eight human leukaemia samples (4 childhood, 4 adult) were exposed to 1 hour of single concentrations of daunorubicin, DaunoXome (courtesy NeXstar Pharmaceuticals Inc, USA), cyclophosphamide and 4-hydroperoxycyclophosphamide (4-HC, courtesy Dr. M. Colvin, Duke University, USA), followed by SCGE/high resolution CLSM with quantitation of total excised DNA. Differences between cases/drug moieties/exposures were analysed.

RESULTS

Although generally equal effect dose levels for DaunoXome were lower than for standard daunorubicin, patients/individual neoplastic cells differed considerably in optimal dose levels. Conventional cyclophosphamide in comparison to 4-HC showed inconsistent results indicating considerable differences in the level of drug resistance to the conventional product.

CONCLUSIONS

Direct testing for drug resistance patterns in DNA directed drug moieties by SCGE/CLSM reveals individual variability of human malignant cell lines warranting comparison with results of MTT testing and in-vivo patient response.