Methylene-linked bis-phenylbenzimidazoles - a new scaffold to target telomeric DNA/RNA hybrid duplex.

We report a series of novel methylene-linked bis-phenylbenzimidazoles intercalators that stabilize telomeric DNA/RNA hybrid (tDRH) structures by up to 7.2 °C at a 1 µM ligand concentration while having negligible affinity for DNA/DNA duplexes, although with a low affinity for quadruplex DNA. We have used molecular modelling studies to rationalize this selectivity, concluding that the methylene spacer between the terminal benzimidazole and phenylene moieties plays a key role in facilitating the bis-intercalating process. This scaffold may be used to develop chemical tools or new therapeutics to selectively target the telomeric DNA/RNA duplex without affecting normal genomic DNA.

ABCB1 genetic polymorphism influences the pharmacology of the new pyrrolobenzodiazepine derivative SJG-136.

ATP-binding cassette transporter P-glycoprotein (ABCB1) is responsible for the multidrug resistance (MDR1) phenotype observed in cancer cells. SJG-136, a new pyrrolobenzodiazepine dimer, is a sequence-dependent DNA crosslinking agent and substrate of ABCB1. We previously showed that colon cancer cell lines expressing high levels of ABCB1 showed a lower sensitivity to SJG-136. Here, we show that in 3T3 isogenic fibroblasts, ABCB1 genetic polymorphism differentially affects ABCB1 gene expression and transport function. However, this genotype-phenotype relationship was not observed in immortalized lymphocytes, which expressed 10- to 1000-fold less ABCB1 than colon cancer cell lines. Consistent with this, the cytotoxicity of SJG-136 in 3T3 fibroblasts was affected by ABCB1 genetic polymorphism but not in immortalized lymphocytes. ABCB1 genetic polymorphism is therefore likely to affect drug sensitivity in tissues expressing high levels of the transporter and in which significant variability is observed.

Anaemia as a risk stratification tool for symptomatic patients referred via the two-week wait pathway for colorectal cancer.

Introduction Anaemia is associated with cancer. In 2014 a new form was introduced in our department requesting a haemoglobin (Hb) result on every two-week wait referral for suspected colorectal cancer (CRC). The aim of this study was to review the impact of this intervention. In particular, the significance of any evidence of anaemia (without additional indices) was investigated. Methods A review was conducted of 1,500 consecutive suspected CRC referrals recorded prospectively over a 10-month period. Data on demographics, referral Hb, referral criteria and outcomes were analysed. Anaemia was defined according to World Health Organization criteria (Hb <120g/l for women, Hb <130g/l for men). Results Overall, 1,015 patients were eligible for inclusion in the study. Over a third (38.2%) were documented as anaemic on referral. These patients were three times more likely to be diagnosed with CRC than non-anaemic patients (odds ratio [OR]: 3.22, 95% confidence interval [CI]: 1.87-5.57). Using a more stringent threshold (Hb <100g/l for women and <110g/l for men), they were four times more likely to have CRC (OR: 4.27, 95% CI: 2.35-7.75). Almost a quarter (23.7%) were actually anaemic at the time of referral but not referred with anaemia. In this subgroup, there was a 2.8-fold increase in risk of CRC diagnosis compared with non-anaemic patients (adjusted OR: 2.77, 95% CI: 1.55-4.95). Conclusions Nearly a quarter of patients not referred with iron deficiency anaemia had evidence of anaemia and this was still associated with a higher rate of CRC detection. A full blood count alone might help to risk stratify symptoms such as change in bowel habit in patients on urgent pathways and identify those cases most likely to benefit from invasive investigation.

Preclinical pharmacology of the pyrrolobenzodiazepine (PBD) monomer DRH-417 (NSC 709119).

The pyrrolobenzodiazepine monomer DRH-417 is a member of the anthramycin group of anti-tumor antibiotics that bind covalently to the N2 of guanine within the minor groove of DNA. DRH-417 emerged from the EORTC-Drug Discovery Committee and NCI 60 cell line in vitro screening programs as a potent antiproliferative agent with differential sensitivity towards certain cancer types such as melanoma, breast and renal cell carcinoma (mean IC(50) = 3 nM). DRH-417 was therefore tested for in vivo activity. The maximum tolerated dose (MTD) was established as 0.5 mg/kg given i.p. Marked anti-tumor activity was seen in two human renal cell cancers, one breast cancer and a murine colon tumor model (p<0.01). A selective HPLC (LC/MS) analytical method was developed and plasma pharmacokinetics determined. At a dose of 0.5 mg kg(-1), the plasma AUC was 540 nM h (197.1 ng h ml(-1)) and the peak plasma concentration (171 nM [62.4 ng ml(-1)]) occurred at 30 min., reaching doses levels well above those needed for in vitro antiproliferative activity. Genomic profiling of in vivo sensitive tumors revealed that the latter have an activated insulin-like growth factor signaling pathway.

Non-small cell lung cancer with distal cutaneous metastases in a patient with a previously treated colorectal carcinoma.

Cutaneous manifestations of visceral carcinomas are scarce, occurring in around 0.7-12% of internal malignancies. Lung cancer is one of the most common sources of skin metastasis, particularly in male patients. We present a case of cutaneous metastasis in a man with concurrent lung lesions and a previously treated colorectal carcinoma. Immunohistochemistry markers for both skin and lung lesions were strongly positive for carcinoembryonic antigen and cytokeratin 20, suggesting an intestinal primary tumour. However, colonoscopy excluded new and metastatic bowel lesions. After multidisciplinary team meetings, which reviewed the clinical, radiological and immunohistochemistry findings, it was concluded to be a non-small cell lung cancer with skin metastasis. This case presented an interesting diagnostic challenge, and highlighted the importance of cross-specialty liaison and investigation to reach the correct diagnosis.

2-Chlorodeoxyadenosine treatment of low-grade lymphomas.

PURPOSE: Because of the need to identify effective new agents in the treatment of non-Hodgkin's lymphoma and because of the high activity of the purine analog 2-chlorodeoxyadenosine (2-CdA) against chronic lymphocytic leukemia and hairy cell leukemia, a phase II trial of 2-CdA was initiated in patients with low-grade lymphocytic lymphomas. PATIENTS AND METHODS: Forty patients with low-grade lymphocytic lymphomas including diffuse small lymphocytic, follicular small-cleaved, and follicular mixed histologies were enrolled onto the study. Conventional therapies had failed in all patients, and six patients had lymph node biopsies showing evidence of histologic evolution to a higher-grade lymphoma. A total of 107 courses of 2-CdA were administered. There were 27 males and 13 females. The median age was 59 years (range, 37 to 80 years). Patients had received a median of three prior therapies (range, one to six therapies). RESULTS: An overall response rate of 43% was achieved, with eight patients experiencing complete responses (CRs) and nine patients experiencing partial responses (PRs). The duration of responses ranged from 1 to greater than 33 months without maintenance therapy (median duration of response, 5 months). Histology and prior therapy history did not seem to correlate with responses. Significant toxicity was limited to bone marrow suppression; 18% of patients developed neutropenia, and 30% developed thrombocytopenia. CONCLUSIONS: This phase II trial demonstrates that 2-CdA is an effective antilymphocyte, antineoplastic agent with significant activity as a single agent in patients with recurrent or refractory low-grade lymphocytic lymphoma. Responses were achieved with an acceptable toxicity profile. Further trials of this agent in previously untreated patients and in combination regimens are indicated and will be developed.

Influence of P-glycoprotein expression on in vitro cytotoxicity and in vivo antitumour activity of the novel pyrrolobenzodiazepine dimer SJG-136.

SJG-136 is a novel pyrrolobenzodiazepine dimer analogue that acts as a minor-groove interstrand DNA cross-linking agent. The present study investigated the impact of ABCB1 (mdr-1) expression on the activity of SJG-136 using both in vitro and in vivo systems. SJG-136 was highly potent in the colon cancer cell lines HCT-116, HT-29 and SW620 (IC50 0.1-0.3 nM). However, HCT-8 and HCT-15 cells expressing significant levels of mdr-1 were less sensitive (IC50 2.3 and 3.7 nM, respectively) using a SRB assay. The cytotoxicity was increased in HCT-15 and A2780(AD) in presence of 5 microg/ml verapamil. Mdr-1 mRNA expression was determined by qRT-PCR and correlated to SJG-136 IC50s (r2=0.86, P=0.0001). Isogenic 3T3 cells expressing mdr-1 cDNA (3T3 pHamdr-1) were less sensitive to SJG-136 than the parental 3T3 cells (IC50 208 and 6.3 nM, respectively). Finally, SJG-136 (120 microg/kg/d dx5) was highly active against A2780 xenografts (SGD=275) but not A2780(AD) xenografts (SGD=67).

Gaucher disease. Clinical, laboratory, radiologic, and genetic features of 53 patients.

We have reviewed our experiences with the clinical, laboratory, radiologic, and genetic features of 53 patients with Gaucher disease. Most were evaluated during early adult life, with a mean age of 33 years. Our patients were evaluated in a referral center, and therefore the data need to be interpreted with caution when applied to the general patient population, which includes a greater proportion of very mild cases. Thirty-nine patients were Ashkenazi Jews, 13 were non-Jewish and 1 was half-Jewish. The most common presenting symptom was bleeding related to splenomegaly and thrombocytopenia. The chronic symptoms, evaluated an average of 20 years after the diagnosis had been established, were mainly skeletal. Splenectomy had been performed in 43% of our patients and there was no evidence that this procedure accelerated the progression of liver and bone involvement. DNA from the patients was examined for 20 different mutations. The association between the 1226G/1226G genotype and a milder clinical course, and between the 1226G/84GG and 1226/1448C genotypes with more severe clinical manifestations, was confirmed. Repeated follow-up examinations in 29 patients revealed that in the majority of the patients, progression of the disease occurs during childhood, adolescence, or early adulthood with a marked tendency for stabilization thereafter. This observation suggests that Gaucher disease in most of the patients is not a relentless progressive disorder but a rather stable disorder during adulthood. The indications for the newly introduced intravenous enzyme replacement therapy as well as of future experimental treatments should be examined in the light of the natural history of the disease.

Structure of a covalent DNA minor groove adduct with a pyrrolobenzodiazepine dimer: evidence for sequence-specific interstrand cross-linking.

The structure of the interstrand cross-linked adduct formed between a C8-C8'-linked pyrrolobenzodiazepine (PBD) dimer (DSB-120; 1,1'-(propane-1,3-diyldioxy)bis[(11aS)-7-methoxy-1,2,3,11a-t etrahydro-5H- pyrrolo[2,1-c][1,4]benzodiazepin-5-one]) and a self-complementary d(CICGATCICG)2 duplex has been determined from high-field 1D- and 2D-NMR data using a simulated annealing procedure. The refined structure supports earlier observations from solution NMR experiments and indicates that the covalently bound molecule spans six DNA base pairs in the minor groove, forming a symmetric cross-link between the spatially separated internal guanines and with active recognition of an embedded 5'-GATC bonding site. This result confirms that template-directed approaches are useful for the design of linked DNA-interactive PBD dimers with viable DNA cross-linking potential. Further, head-to-head connection of the PBD moieties results in an overall retention of 5'-GA bonding site preference for each alkylating PBD subunit. Structural analysis indicates that cross-link formation results in a localized perturbation of the DNA duplex, attributable in part to a mutual reduction in dynamic mobility or "covalent clamping" within the Gua4-Cyt7 base tract. However, ligand-induced distortion is confined to the Cyt7 and Ino8 residues on each strand. The Gua(N2)-Gua(N2) cross-link is stabilized by two directed H-bonds from the formed animal residues to N3 acceptor atoms of adenine bases on the 3'-side of each covalently modified guanine. Evidence for sequence-specific cross-linking with DSB-120 is provided by extended modeling studies which suggest that recognition of the favored d(.GATC.) motif is dominated by van der Waals steric factors, although electrostatic and H-bonded interaction terms also play a key role. This conclusion supports recent covalent footprinting studies revealing that this PBD dimer shows a selectivity for embedded base sequences of the type 5'-(pu/py)GATC(py/pu).

Comparison of a DSB-120 DNA interstrand cross-linked adduct with the corresponding bis-tomaymycin adduct: an example of a successful template-directed approach to drug design based upon the monoalkylating compound tomaymycin.

The interstrand cross-linked DSB-120-d(CICG*ATCICG)2 DNA adduct (*indicates covalently modified guanine) was examined by two-dimensional NMR and compared to the bis-tomaymycin adduct on the same oligomer. Tomaymycin and DSB-120 form self-complementary adducts with the d(CICGATCICG)2 duplex sequence in which the covalent linkage sites occur between C11 of either drug and the exocyclic 2-amino group of the single reactive guanine on each strand of d(CICGATCICG)2. In the case of DSB-120, this is evidence for the formation of a guanine--guanine DNA interstrand cross-link. Both drugs show formation of an S stereo-chemistry at the covalent linkage site with an associated 3' orientation. While the majority of DNA in these adducts appears to be B-form, DSB-120 interstrand cross-linking induces atypical properties in the 8I nucleotide, indicated by broadening of the 8IH2 proton resonance, non-C2' endo sugar geometry, and unusually weak internucleotide NOE connectivity to the 7C nucleotide. Tomaymycin does not produce this regional dislocation. For tomaymycin, while there are strong NOE connectivities from protons on the five-membered ring to the 8IH2 proton on the floor of the minor groove, the equivalent internucleotide connectivities in DSB-120 are weaker. This indicates that the tomaymycin tail is close to the floor of the minor groove, while the five-membered ring of DSB-120 is more shallowly immersed, perhaps due to strain from cross-linking with a very short linker unit. Last, the conformational stresses induced on the duplex by DSB-120 appear to make the region of covalent attachment more accessible to solvent than is the case for tomaymycin. The 4GN2Hb resonance appears in 100% D2O on the tomaymycin adduct but is only observed in 90% H2O/10% D2O for the DSB-120 adduct. On the basis of these results, the strategies for template-directed DNA cross-linker design are assessed.

Design, synthesis, and evaluation of a novel pyrrolobenzodiazepine DNA-interactive agent with highly efficient cross-linking ability and potent cytotoxicity.

A novel sequence-selective pyrrolobenzodiazepine (PBD) dimer 5 (SJG-136) has been developed that comprises two C2-exo-methylene-substituted DC-81 (3) subunits tethered through their C8 positions via an inert propanedioxy linker. This symmetric molecule is a highly efficient minor groove interstrand DNA cross-linking agent (XL(50) = 0.045 microM) that is 440-fold more potent than melphalan. Thermal denaturation studies show that, after 18 h incubation with calf thymus DNA at a 5:1 DNA/ligand ratio, it increases the T(m) value by 33.6 degrees C, the highest value so far recorded in this assay. The analogous dimer 4 (DSB-120) that lacks substitution/unsaturation at the C2 position elevates melting by only 15.1 degrees C under the same conditions, illustrating the effect of introducing C2-exo-unsaturation which serves to flatten the C-rings and achieve a superior isohelical fit within the DNA minor groove. This behavior is supported by molecular modeling studies which indicate that (i) the PBD units are covalently bonded to guanines on opposite strands to form a cross-link, (ii) 5 has a greater binding energy compared to 4, and (iii) 4 and 5 have equivalent binding sites that span six base pairs. Dimer 5 is significantly more cytotoxic than 4 in a number of human ovarian cancer cell lines (e.g., IC(50) values of 0.0225 nM vs 7.2 nM, respectively, in A2780 cells). Furthermore, it retains full potency in the cisplatin-resistant cell line A2780cisR (0.024 nM), whereas 4 loses activity (0.21 microM) with a resistance factor of 29.2. This may be due to a lower level of inactivation of 5 by intracellular thiol-containing molecules. A dilactam analogue (21) of 5 that lacks the electrophilic N10-C11/N10'-C11' imine moieties has also been synthesized and evaluated. Although unable to interact covalently with DNA, 21 still stabilizes the helix (Delta T(m) = 0.78 degrees C) and has significant cytotoxicity in some cell lines (i.e., IC(50) = 0.57 microM in CH1 cells), presumably exerting its effect through noncovalent interaction with DNA.

Design, synthesis, and evaluation of a novel sequence-selective epoxide-containing DNA cross-linking agent based on the pyrrolo[2, 1-c][1,4]benzodiazepine system.

Synthetic routes have been investigated to prepare a novel C8-epoxide-functionalized pyrrolo[2,1-c][1,4]benzodiazepine 6 as a potential sequence-selective DNA cross-linking agent (Wilson et al. Tetrahedron Lett. 1995, 36, 6333-6336). A successful synthesis was accomplished via a 10-step route involving a pro-N10-Fmoc cleavage method that should have general applicability to other pyrrolobenzodiazepine (PBD) molecules containing acid- or nucleophile-sensitive groups. During the course of this work, a one-pot reductive cyclization procedure for the synthesis of PBD N10-C11 imines from nitro dimethyl acetals was also discovered, although this method results in C11a racemization which can reduce DNA binding affinity and cytotoxicity. The target epoxide 6 was shown by thermal denaturation studies to have a significantly higher DNA-binding affinity than the parent DC-81 (3) or the C8-propenoxy-PBD (15), which is structurally similar but lacks the epoxide moiety. The time course of effects upon thermal denaturation indicated a rapid initial binding phase followed by a slower phase consistent with the stepwise cross-linking of DNA observed for a difunctional agent. This was confirmed by an electrophoretic assay which demonstrated efficient induction of interstrand cross-links in plasmid DNA at concentrations >1 microM. Higher levels of interstrand cross-linking were observed at 24 h compared to 6 h incubation. A Taq polymerase stop assay indicated a preference for binding to guanine-rich sequences as predicted for bis-alkylation in the minor groove of DNA by epoxide and imine moieties. The pattern of stop sites could be partly rationalized by molecular modeling studies which suggested low-energy models to account for the observed binding behavior. The epoxide PBD 6 was shown to have significant cytotoxicity (45-60 nM) in the A2780, CH1, and CH1cis(R) human ovarian carcinoma cell lines and an IC(50) of 0.2 microM in A2780cis(R). The significant activity of 6 in the cisplatin-resistant CH1cis(R) cell line (IC(50) = 47 nM) gave a resistance factor of 0.8 compared to the parent cell line, demonstrating no cross-resistance with the major groove cross-linking agent cisplatin.

Effect of A-ring modifications on the DNA-binding behavior and cytotoxicity of pyrrolo[2,1-c][1,4]benzodiazepines.

Several A-ring-modified analogues of the DNA-binding antitumor agent DC-81 (5) have been synthesized in order to study structure-reactivity/cytotoxicity relationships. For two molecules (23 and 30) the modifications required the addition of a fourth ring to give the novel dioxolo[4,5-h]- and dioxano[5,6-h]pyrrolo[2,1-c][1, 4]benzodiazepin-11-one (PBD) ring systems, respectively. Another three analogues (34, 38, and 48) have the native benzenoid A-ring replaced with pyridine, diazine, or pyrimidine rings to give the novel pyrrolo[2,1-c][1,4]pyridodiazepine, pyrrolo[2,1-c][1, 4]diazinodiazepine, and pyrrolo[2,1-c][1,4]pyrimidinodiazepine systems, respectively. The other new analogues (16a,b) have extended chains at the C8-position of the DC-81 structure. During the synthesis of these compounds, a novel tin-mediated regiospecific cleavage reaction of the dioxole intermediate 18 was discovered, leading to the previously unknown iso-DC-81 (20). In addition, an unusual simultaneous nitration-oxidation reaction of 4-(3-hydroxypropoxy)-3-methoxybenzoic acid (8) was found to produce 3-(4-carboxy-2-methoxy-5-nitrophenoxy)propanoic acid (9), a key intermediate, in high yield. In general, the results of cytotoxicity and DNA-binding studies indicated that none of the changes made to the A-ring of the PBD system significantly improved either binding affinity or cytotoxicity in comparison to DC-81. This result suggests that the superior potency of natural products such as anthramycin (1), tomaymycin (2), and sibiromycin (3) is due entirely to differences in C-ring structure, and in particular exo or endo unsaturation at the C2-position and C2-substituents containing unsaturation. This study also provided information regarding the influence of A-ring substitution pattern on the relative stability of the interconvertible N10-C11 carbinolamine, carbinolamine methyl ether, and imine forms of PBDs.

Synthesis, in vitro antiproliferative activity, and DNA-binding properties of hybrid molecules containing pyrrolo[2,1-c][1, 4]benzodiazepine and minor-groove-binding oligopyrrole carriers.

The synthesis, biological activity, and DNA-binding properties of a series of four hybrids prepared by combining polypyrrole minor groove binders and pyrrolo[2,1-c][1,4]benzodiazepine (PBD) 13, related to the naturally occurring anthramycin (3) and DC-81 (4), have been described, and structure-activity relationships have been discussed. These hybrids 22-25 contain from one to four pyrrole units, respectively. To investigate sequence selectivity and stability of drug/DNA complexes, DNase I footprinting and arrested polymerase chain reaction (PCR) were performed on human c-myc oncogene, estrogen receptor gene, and human immunodeficiency virus type 1 long terminal repeat (HIV-1 LTR) gene sequences. The antiproliferative activity of the hybrids has been tested in vitro on human myeloid leukemia K562 and T-lymphoid Jurkat cell lines and compared to antiproliferative effects of the natural product distamycin A 1, its tetrapyrrole homologue 17, DC 81 (4), and the PBD methyl ester 12. The results obtained demonstrate that the hybrids 22-25 exhibit different DNA-binding activity with respect to both distamycin A 1 and PBD 12. In addition, a direct relationship was found between number of pyrrole rings present in the hybrids 22-25 and stability of drug/DNA complexes. With respect to antiproliferative effects, it was found that the increase in the length of the polypyrrole backbone leads to an increase of in vitro antiproliferative effects, i.e., the hybrid 25 containing the four pyrroles is more active than 22, 23, and 24 both against K562 and Jurkat cell lines.

N2,N4,N6-tri(hydroxymethyl)-N2,N4,N6-trimethylmelamine (trimelamol) is an efficient DNA cross-linking agent in vitro.

An investigation of the mechanism of action of the antitumour agent trimelamol has established that it is an efficient interstrand DNA cross-linker in vitro, comparable to nitrogen mustards such as melphalan. Studies have shown that the cross-linking reaction is acid-catalysed but, unlike the nitrogen mustards, only partially reversible after treatment with piperidine. The bisalkylation (cross-linking) reaction appears to be concerted, and no "second arm" reaction has been detected. The results of thermal denaturation studies are consistent with general DNA binding, and suggest a preference for GC-rich sites. The acid-catalysed reaction of trimelamol with a model nucleophile (thiophenol) has also been investigated and an adduct resulting from displacement of the three carbinolamine functions has been isolated and characterized.

Selection bias from differential residential mobility as an explanation for associations of wire codes with childhood cancer.

Several studies of childhood cancer, especially leukemia, in residential areas have reported an association with wire configuration codes. These codes were suggested to be surrogates of electromagnetic field exposure. However, the selection criteria used in several of the studies caused the case and control populations to be non-comparable, especially with respect to residential mobility. Specifically, controls were required to be residentially stable but cases were not. Thus, an artificial association between residential mobility and cancer was created by the subject selection procedure. The present study of 5721 residences in Columbus, Ohio was conducted to learn if bias due to differences in residential mobility, rather than electromagnetic fields, could explain the reported association between wire configuration codes and childhood cancer. It was found that the proportion of homes classified as "high" wire code in the non-stable population was 31% greater than the corresponding proportion in the stable population. This finding shows that high wire codes are associated with homes in which the residents are mobile and low wire codes are associated with homes occupied by stable residents. Thus, as a consequence of this association between residential mobility and high wire codes, studies that created an artificial association between residential mobility and childhood cancer will also produce a false association between high wire codes and cancer.

Elevated maternal serum relaxin concentrations throughout pregnancy in singleton gestations after superovulation.

OBJECTIVE: To test the hypothesis that superovulation results in elevated maternal circulating relaxin concentrations throughout the second and third trimesters of pregnancy, independent of the pattern of hCG secretion. METHODS: Two groups of women with singleton gestations were studied: a group of nine women who achieved pregnancy after stimulation with human menopausal gonadotropin and a group of six women who achieved pregnancy without prior stimulation. Peripheral blood samples were drawn approximately every 5 weeks throughout the second and third trimesters. Serum relaxin concentrations were measured using a human relaxin-specific enzyme-linked immunosorbent assay; hCG was measured by an immunofluorometric assay. RESULTS: The stimulated group had significantly higher relaxin levels throughout pregnancy (P=.007, multivariate analysis of variance) than did nonstimulated controls. The mean relaxin level in stimulated patients was 1.78 ng/mL (95% confidence interval [CI] 1.5, 2.17) and in nonstimulated subjects the level was 0.73 ng/mL (95% CI 0.59, 1.25). Spline fits demonstrated that stimulated patients had higher relaxin levels throughout the second and third trimesters. There was no significant difference in hCG concentrations between the two groups (P=.61). CONCLUSION: In singleton gestations after superovulation, maternal serum relaxin concentrations are significantly higher throughout the second and third trimesters of pregnancy. These differences are independent of the pattern of hCG secretion. It appears that luteal relaxin secretion is controlled by factors in addition to hCG.

Utility of computed tomography for surveillance of small abdominal aortic aneurysms. Preliminary report.

To assess the ability of computed tomography to predict the potential for expansion of small abdominal aortic aneurysms, we analyzed the computed tomographic scans of 30 patients who had two or more abdominal computed tomographic scans at least 6 months apart between 1979 and 1989. Clinical variables and 10 defined objective characteristics of computed tomography were evaluated. Twenty-five men and five women with abdominal aortic aneurysms ranging from 30 to 64 mm (mean, 45 mm) were followed up with serial computed tomographic scans for a mean (+/- SE) of 26 +/- 3 months. In 19 patients, enlargement of aneurysm diameter of 3 mm or more on serial computed tomographic scans was noted, whereas in 11, there was little or no expansion. Of the clinical variables studied, only serum cholesterol correlated with an increased risk of expansion. Thrombus area, measured by computed tomography, was 7.3 +/- 0.9 cm2 in enlarging aneurysms vs 4.3 +/- 0.9 cm2 in stable aneurysms. Based on these preliminary data, we conclude that computed tomography may provide valuable information about the likelihood of future expansion of small abdominal aortic aneurysms.

Preclinical pharmacology and antitumour activity of the novel sequence-selective DNA minor-groove cross-linking agent DSB-120.

We examined the in vitro cytotoxicity, antitumour activity and preclinical pharmacokinetics of the novel sequence-selective, bifunctional alkylating agent DSB-120, a synthetic pyrrolo[1,4][2,1-c]benzodiazepine dimer. DSB-120 was shown to be a potent cytotoxic agent in vitro against a panel of human colon carcinomas [50% growth-inhibitory concentration (IC50) 42 +/- 7.9 nM, mean +/- SE, n = 7] and two rodent tumours (L1210 and ADJ/PC6). Antitumour activity was assessed in the bifunctional alkylating-agent-sensitive murine plasmacytoma ADJ/PC6 using a variety of administration protocols. The maximal antitumour effects were observed following a single i.v. dose but the therapeutic index was only 2.6. DSB-120 was less effective when given i.p. either singly or by a daily x 5 schedule. After a single i.v. dose at the maximum tolerated dose (MTD, 5 mgkg-1) the plasma elimination was biphasic, with a short distribution phase (t1/2 alpha 4 min) being followed by a longer elimination phase (t1/2 beta 38 min). Peak plasma concentrations were 25 micrograms ml-1, the clearance was 1.3 ml g-1 h-1 and the AUC0-infinity was 230 micrograms ml-1 min. Concentrations of DSB-120 in ADJ/PC6 tumours were very low, showing a peak of 0.4 micrograms g-1 at 5 min. The steady-state tumour/plasma ratio was about 5% and the AUC was only 2.5% of that occurring in the plasma. DSB-120 appeared to be unstable in vivo, with only 1% of an administered dose being recovered unchanged in 24-h urine samples. Plasma protein binding was extensive at 96.6%. In conclusion, the poor antitumour activity of DSB-120 may be a consequence of low tumour selectivity and drug uptake as a result of high protein binding and/or extensive drug metabolism in vivo.

Studies on the stability of trimelamol, a carbinolamine-containing antitumor drug.

The stability of trimelamol (N2,N4,N6-trimethylol-N2,N4,N6-trimethylmelamine) a synthetic carbinolamine-containing antitumor drug, has been studied. Two major degradation pathways have been characterized and a unified mechanism proposed to rationalize the chemistry involved. One degradation pathway involves the consecutive loss of hydroxymethylene units by elimination of formaldehyde until the parent trimethylmelamine (4) results. An HPLC method was used to obtain kinetic data for the loss of trimelamol and to monitor the order of appearance of three degradation products. This pathway was shown to follow first-order kinetics at all pH values studied at both 18 and 37 degrees C. The second pathway involves the coupling of two trimelamol molecules via a methylene bridge to form bis(trimelamol) (6) which had been previously referred to in the literature as a "polymer". This reaction is acid catalyzed and temperature dependent. Bis(trimelamol) is virtually water insoluble and adheres strongly to glass surfaces. Finally, t1/2 values have been determined for trimelamol in aqueous solution at different temperatures, and the kinetics of formation of degradation products has been studied over a period of 30 h under a variety of conditions of pH and temperature. The data reported here are relevant to both the formulation and clinical administration of trimelamol, and may contribute to an understanding of mechanism of action and future analogue development studies.