Electron localization and magnetism in SrRuO3 with non-magnetic cation substitution

The destruction of the ferromagnetism of alloyed SrRuO(3) can be caused by electron localization at the substitution sites. Among all the non-magnetic cations that enter the B site, Zr(4+) is the least disruptive to conductivity and ferromagnetism. This is because Zr(4+) does not cause any charge disorder, and its empty d electron states which are poorly matched in energy with the Ru t(2g)(4) states cause the least resonance scattering of Ru's d electrons. Conducting Sr(Ru, Zr)O(3) may be used as an electrode for perovskite-based thin film devices, while its insulating counterpart provides unprecedented magnetoresistance, seldom seen in other non-manganite and non-cobaltite perovskites.

Functional analysis of multiple genomic signatures demonstrates that classification algorithms choose phenotype-related genes

Gene expression signatures of toxicity and clinical response benefit both safety assessment and clinical practice; however, difficulties in connecting signature genes with the predicted end points have limited their application. The Microarray Quality Control Consortium II (MAQCII) project generated 262 signatures for ten clinical and three toxicological end points from six gene expression data sets, an unprecedented collection of diverse signatures that has permitted a wide-ranging analysis on the nature of such predictive models. A comprehensive analysis of the genes of these signatures and their nonredundant unions using ontology enrichment, biological network building and interactome connectivity analyses demonstrated the link between gene signatures and the biological basis of their predictive power. Different signatures for a given end point were more similar at the level of biological properties and transcriptional control than at the gene level. Signatures tended to be enriched in function and pathway in an end point and model-specific manner, and showed a topological bias for incoming interactions. Importantly, the level of biological similarity between different signatures for a given end point correlated positively with the accuracy of the signature predictions. These findings will aid the understanding, and application of predictive genomic signatures, and support their broader application in predictive medicine.

Genomic indicators in the blood predict drug-induced liver injury

Genomic biomarkers for the detection of drug-induced liver injury (DILI) from blood are urgently needed for monitoring drug safety. We used a unique data set as part of the Food and Drug Administration led MicroArray Quality Control Phase-II (MAQC-II) project consisting of gene expression data from the two tissues (blood and liver) to test cross-tissue predictability of genomic indicators to a form of chemically induced liver injury. We then use the genomic indicators from the blood as biomarkers for prediction of acetaminophen-induced liver injury and show that the cross-tissue predictability of a response to the pharmaceutical agent (accuracy as high as 92.1%) is better than, or at least comparable to, that of non-therapeutic compounds. We provide a database of gene expression for the highly informative predictors, which brings biological context to the possible mechanisms involved in DILI. Pathway-based predictors were associated with inflammation, angiogenesis, Toll-like receptor signaling, apoptosis, and mitochondrial damage. The results show for the first time and support the hypothesis that genomic indicators in the blood can serve as potential diagnostic biomarkers predictive of DILI.

A comparison of batch effect removal methods for enhancement of prediction performance using MAQC-II microarray gene expression data

Batch effects are the systematic non-biological differences between batches (groups) of samples in microarray experiments due to various causes such as differences in sample preparation and hybridization protocols. Previous work focused mainly on the development of methods for effective batch effects removal. However, their impact on cross-batch prediction performance, which is one of the most important goals in microarray-based applications, has not been addressed. This paper uses a broad selection of data sets from the Microarray Quality Control Phase II (MAQC-II) effort, generated on three microarray platforms with different causes of batch effects to assess the efficacy of their removal. Two data sets from cross-tissue and cross-platform experiments are also included. Of the 120 cases studied using Support vector machines (SVM) and K nearest neighbors (KNN) as classifiers and Matthews correlation coefficient (MCC) as performance metric, we find that Ratio-G, Ratio-A, EJLR, mean-centering and standardization methods perform better or equivalent to no batch effect removal in 89, 85, 83, 79 and 75% of the cases, respectively, suggesting that the application of these methods is generally advisable and ratio-based methods are preferred.

Assessing sources of inconsistencies in genotypes and their effects on genome-wide association studies with HapMap samples

The discordance in results of independent genome-wide association studies (GWAS) indicates the potential for Type I and Type II errors. We assessed the repeatibility of current Affymetrix technologies that support GWAS. Reasonable reproducibility was observed for both raw intensity and the genotypes/copy number variants. We also assessed consistencies between different SNP arrays and between genotype calling algorithms. We observed that the inconsistency in genotypes was generally small at the specimen level. To further examine whether the differences from genotyping and genotype calling are possible sources of variation in GWAS results, an association analysis was applied to compare the associated SNPs. We observed that the inconsistency in genotypes not only propagated to the association analysis, but was amplified in the associated SNPs. Our studies show that inconsistencies between SNP arrays and between genotype calling algorithms are potential sources for the lack of reproducibility in GWAS results.

Effects of bone morphogenetic protein-2 on proliferation and angiogenesis in oral squamous cell carcinoma

Experimental data and limited patient experience suggest that rhBMP-2 can be used to regenerate bone in acquired segmental defects of the mandible. Most of these defects are caused by resection of oral squamous cell carcinoma (OSCC) and the biologic effects of rhBMP-2 on these carcinoma cells are unknown. The objective of this study was to determine whether rhBMP-2 produces adverse effects on proliferation and angiogenesis in OSCC, two biologic processes critical to tumor formation. In vitro studies included treating OSCC cells with rhBMP-2 or an adenoviral vector containing the cDNA for BMP-2. In vivo studies involved co-transplantation of OSCC cells with bone marrow stromal cells genetically modified to over express BMP-2, to mimic a clinically relevant scenario for regenerating bone using cell-based therapy in a wound containing microscopic residual disease. Proliferation, as measured by a MTT assay in vitro and tumor growth in vivo was not affected by treatment with BMP-2. Angiogenesis, measured by secretion of the proangiogenic molecules VEGF and IL-8 in vitro and microvessel density in vivo, was not affected. Exposure of OSCC cells to BMP-2 does not stimulate proliferation or angiogenesis. Further studies are needed before using rhBMP-2 for bone tissue engineering in oral cancer-related defects.

Toluene diisocyanate enhances human bronchial epithelial cells' permeability partly through the vascular endothelial growth factor pathway

BACKGROUND

Toluene diisocyanate (TDI) is a recognized chemical asthmogen; yet, the mechanisms of its toxicity have not been elucidated.

OBJECTIVE

To investigate the influence of TDI on the permeability of human bronchial epithelial cell (HBE; HBE135-E6E7) monolayers in vitro, and the expression of vascular endothelial growth factor (VEGF) in these cells.

METHODS

TDI-human serum albumin (HSA) conjugates were prepared by a modification of Son's method. Fluorescein isothiocyanate-labelled dextran and transmission electron microscopy were used to evaluate the effects of TDI-HSA on HBE135-E6E7 permeability. RT-PCR and ELISA were used to evaluate VEGF gene expression and protein release from HBE135-E6E7 cells stimulated by TDI-HSA. A VEGF-neutralizing antibody was used in monolayer permeability experiments to determine the role of the VEGF pathway in this process.

RESULTS

TDI-HSA significantly increased the permeability coefficients of HBE135-E6E7 monolayers (P<0.01). TDI-HSA treatment significantly increased the expression of VEGF165 and VEGF189 genes (P<0.01). ELISA showed that TDI significantly induces VEGF release from HBE135-E6E7 cells. Cells treated with TDI-HSA and VEGF-neutralizing antibody had significantly lower permeability coefficients than cells treated with TDI-HSA only (P<0.01), but still significantly higher than control cells (P<0.01). Cells treated with TDI-HSA had fewer tight junctions (TJs) than control and HSA-treated cells, and addition of the anti-VEGF antibody did not restore the original number of TJs.

CONCLUSION

TDI increases the permeability of HBE cell monolayers, partly through a VEGF-mediated pathway. This suggests the importance of VEGF in TDI-induced pulmonary diseases, but shows that other pathways may be involved in the pathogenic process.

In vitro and in vivo anti-leukemia activity of CHR-2845, a cell-targeted HDAC inhibitor for use in monocytic leukemia

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Background: Histone deacetylase inhibitors alter gene expression and induce apoptosis in a wide range of cancer cells including those derived from human leukemias. CHR-2845 is a novel hydroxamic acid derivative histone deacetylase inhibitor (HDACi) which is a selective substrate for the intracellular carboxylesterase hCE-1, whose expression is restricted to cells of the monocyte- macrophage lineage. Methods: We studied the in vitro and in vivo anti-leukemia activity of CHR-2845 using cell proliferation assay, annexin V binding assay, cell cycle analysis, western blot and in vitro primary leukemia cell culture. Results: Both U937 and THP1 cells express high levels of hCE-1 whereas the myeloid cell line, HL60, does not. In comparison to vorinostat, CHR-2845 showed increased anti-proliferative potency (IC50) against monocytic cell lines (THP1, 30 nM vs 700 nM and U937, 30 nM vs 475 nM), compared to a myeloid cell line (HL60, 700nM vs 470 nM). In a broad panel of leukemic cell lines, the potency of CHR-2845 over vorinostat correlated completely with hCE-1 expression. In monocytic cell lines, CHR-2845 induced more apoptosis than vorinostat (THP1: 45±5% vs 11±1% and U937: 23±14% vs 6±1%), as measured by flow cytometry using Annexin V. Biochemical assessment of histone H3 and H4 protein acetylation by Western blot also indicateed that CHR-2845 is at least 10 times more potent than vorinostat in monocytic cell lines but not in HL-60 cells. This increase in histone acetylation was associated with increased phosphohistone H2AX, indicating formation of double-strand DNA breaks induced by this compound. These data for CHR-2845 and vorinostat on apoptosis and histone acetylation in THP1 and U937 versus HL60 cells, confirmed the selectivity of this novel compound for cells of the monocytic lineage. We also studied the anti-leukemia activity of CHR-2845 in primary leukemia cells from 8 patients with acute or chronic myelomonocytic leukemia. CHR-2845 decreased proliferation and induced apoptosis more than an equivalent dose of vorinostat in some of the patients we studied. Conclusions: These results indicated that CHR-2845 has potential to be efficacious in the treatment of patients with monocytic leukemia.

[Table: see text]

Treatment and outcomes of elderly versus younger patients with advanced NSCLC at Mayo Clinic Arizona (MCA)

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Background: Non-small cell lung cancer (NSCLC) is predominantly a disease of the elderly. Most patients (pts) present with incurable advanced disease, but chemotherapy for good performance status (PS) pts improves quality and quantity of life. Despite good PS, many elderly pts with metastatic NSCLC do not receive chemotherapy. This study compared treatment, outcomes, and survival in elderly vs younger pts with stage IV NSCLC. Methods: All analytic MCA Cancer Registry pts with stage IV NSCLC from 1998–2007 were retrospectively reviewed for type of therapy and outcome. Pts were analyzed by age: <75 vs ≥75 years old. Categorical variables were compared using chi-squared tests and survival was compared by Cox regression. Results: 344 pts with stage IV NSCLC were identified. 234 (68%) pts were <75 years old, and 110 pts (32%) were ≥75 years old. Median survival for all pts was 7 months. Among 302 pts with treatment data available, 60.8% of pts <75 years old received some form of systemic therapy (chemotherapy/targeted therapy) compared to only 32% of pts ≥ 75 years old (p <0.0001). Among pts with PS 0–1, pts <75 years old more frequently received systemic therapy than elderly patients (88.5% vs 32.1%, p<0.0001); whereas a difference was not evident in pts with PS 2–4 (34.1% vs 41.7%, p=0.49). Median survival in the <75 age group was 7 months vs. 3.4 months in the ≥75 age group (p=0.048). In the <75 age group, median survival was 12 months in pts who received chemotherapy vs. 2 months in the other or no treatment group (p<0.0001). In the elderly group, median survival was 10 months in the chemotherapy group vs. 2 months in the pts who received other or no treatment (p=0.0003). Thus, the median survival was significantly improved among the pts who received systemic therapy independent of age. Statistical significance persisted when stratifying by PS. Conclusions: Pts with stage IV NSCLC have improved survival with systemic therapy independent of age. Our results confirm that despite an improvement in survival similar to younger pts, elderly patients with metastatic NSCLC are often undertreated. Prospective trials should be designed to include metastatic NSCLC patients without age discrimination

No significant financial relationships to disclose.

The prevalence of lymphogranuloma venereum infection in men who have sex with men: results of a multicentre case finding study

Objective:

To determine the prevalence of lymphogranuloma venereum (LGV) and non-LGV associated serovars of urethral and rectal Chlamydia trachomatis (CT) infection in men who have sex with men (MSM).

Design:

Multicentre cross-sectional survey.

Setting:

Four genitourinary medicine clinics in the United Kingdom from 2006–7.

Subjects:

4825 urethral and 6778 rectal samples from consecutive MSM attending for sexual health screening.

Methods:

Urethral swabs or urine and rectal swabs were tested for CT using standard nucleic acid amplification tests. Chlamydia-positive specimens were sent to the reference laboratory for serovar determination.

Main outcome:

Positivity for both LGV and non-LGV associated CT serovars; proportion of cases that were symptomatic.

Results:

The positivity (with 95% confidence intervals) in rectal samples was 6.06% (5.51% to 6.66%) for non-LGV CT and 0.90% (0.69% to 1.16%) for LGV; for urethral samples 3.21% (2.74% to 3.76%) for non-LGV CT and 0.04% (0.01% to 0.16%) for LGV. The majority of LGV was symptomatic (95% of rectal, one of two urethral cases); non-LGV chlamydia was mostly symptomatic in the urethra (68%) but not in the rectum (16%).

Conclusions:

Chlamydial infections are common in MSM attending for sexual health screening, and the majority are non-LGV associated serovars. We did not identify a large reservoir of asymptomatic LGV in the rectum or urethra. Testing for chlamydia from the rectum and urethra should be included for MSM requesting a sexual health screen, but serovar-typing is not indicated in the absence of symptoms. We have yet to identify the source of most cases of LGV in the UK.

Activity of tyrosine kinase inhibitors against human NUP214-ABL1-positive T cell malignancies

Amplification of the NUP214-ABL1 oncogene can be detected in patients with T cell acute lymphoblastic leukemia (T-ALL). We screened 29 patients with T cell malignancies for the expression of NUP214-ABL1 by reverse transcription-polymerase chain reaction (RT-PCR). NUP214-ABL1 was detected in three (10%) patients. These results were confirmed by fluorescence in situ hybridization techniques. We also studied the activity of imatinib, nilotinib and dasatinib against the human NUP214-ABL1-positive cell lines PEER and BE-13. All three tyrosine kinase inhibitors decreased the viability of PEER and BE-13 cells, but nilotinib and dasatinib had >1-log lower IC(50) values than imatinib (P<0.001). In contrast, the NUP214-ABL-negative T-ALL cell line Jurkat, was remarkably resistant to tyrosine kinase inhibition. The inhibition of cellular proliferation was associated with time-dependent induction of apoptosis and inhibition of ABL, CrKL and STAT5 phosphorylation. Moreover, dasatinib was active in a NUP214-ABL1-positive leukemia xenograft murine model and in marrow lymphoblasts from a patient with NUP214-ABL1-positive T-ALL. On the basis of these results, ABL1 kinase inhibitors warrant clinical investigation in patients with NUP214-ABL1-positive T-cell malignancies.

A phase II study of 5-azacitidine for patients with primary and post-essential thrombocythemia/polycythemia vera myelofibrosis

Myelofibrosis (MF; primary or post-essential thrombocythemia/polycythemia vera) is incurable clonal myeloproliferative disorder, with no effective treatment. Epigenetic changes play an important role in cancer pathogenesis through transcriptional silencing of critical tumor suppressor genes. We conducted a phase-II study to evaluate the activity of DNA methyltransferase inhibitor, 5-azacitidine, in patients with MF. Thirty-four patients (76% previously treated) received 5-azacitidine at 75 mg/m(2) subcutaneously daily for 7 days, every 4 weeks. Twelve (35%) patients had abnormal cytogenetics and 19 (70%) of 27 evaluable patients had JAK2(V617F) mutation. Responses occurred in 8 (24%) patients after a median of 5 months (range, 3-10). Partial response occurred in 1 (3%) patient (duration 22+ months) and clinical improvement in 7 (21%) patients (median duration 4 months; range, 2-8.5). Myelosuppression was the major adverse effect, with grade 3-4 neutropenia in 10 (29%) patients. Global DNA methylation assessed by the long interspersed nucleotide element (LINE) bisulfite/pyrosequencing assay decreased from 53% pretherapy to 44% on day 14 (P=0.0014) and returned to 50% at the end of the first 28-day cycle (P=0.016). 5-azacitidine is relatively well tolerated and results in induction of global hypomethylation in patients with MF, but results in limited clinical activity.

Computational prediction of binding hotspots

We combine side-chain modeling, energy minimization and binding free energy calculation to predict point mutations with significant impacts on binding affinities (binding hotspots). Our method achieves high accuracy for two datasets (alanine-scanning mutations in ASEdb and 570 mutations on protease-inhibitor complexes). In particular, we can predict mutations that lead to improved binding with success. We discuss various factors that may contribute the prediction accuracy, including the amino acid to mutate to, and the position of the mutation.

Clustering protein-protein docking predictions

We describe a clustering algorithm for improving protein-protein docking predictions. The algorithm was applied to two sets of predictions for 36 test cases, one set generated with a rigid-body docking algorithm ZDOCK, and the other set with ZDOCK followed by a refinement algorithm RDOCK, and consistent improvement was observed.

Identification and characterization of a novel p42.3 gene as tumor-specific and mitosis phase-dependent expression in gastric cancer

Multiple genetic alterations are attributed to gastric cancer (GC); however, only a few critical genes have been identified so far. In this study, we isolated and characterized a novel gene p42.3, represented as tumor-specific and mitosis phase-dependent expression protein in GC cell line BGC823. Our data showed that the expression of p42.3 was cell cycle-dependent in GC cell lines. Moreover, p42.3 was specifically expressed in primary GC tissues but not in the matched normal mucosa of stomach, and this gene was expressed in diverse embryonic tissues. Furthermore, significant suppression of cell proliferation and tumorigenicity were detected and G(2)/M phase arrest was observed in cell line BGC823 depleted of p42.3 expression by RNAi technique, and we confirmed the expression changes of cyclin B1 and Chk2 following the silence of p42.3. Taken together, we cloned and characterized p42.3 gene that was specifically expressed in GC tumors but not in normal gastric mucosa, and the gene was associated with M-phase regulation. Moreover, p42.3 might be involved in cell proliferation and tumorigenesis; therefore, this gene might have potential applications in the diagnosis or treatment of GC.

An in silico ensemble method for lead discovery: decision forest

Recent progress in combinatorial chemistry and parallel synthesis has radically changed the approach to drug discovery in the pharmaceutical industry. At present, thousands of compounds can be made in a short period, creating a need for fast and effective in silico methods to select the most promising lead candidates. Decision forest is a novel pattern recognition method, which combines the results of multiple distinct but comparable decision tree models to reach a consensus prediction. In this article, a decision forest model was developed using a structurally diverse training data set containing 232 compounds whose estrogen receptor binding activity was tested at the U.S. Food and Drug Administration (FDA)'s National Center for Toxicological Research (NCTR). The model was subsequently validated using a test data set of 463 compounds selected from the literature, and then applied to a large data set with 57,145 compounds as a screening example. The results show that the decision forest method is a fast, reliable and effective in silico approach, which could be useful in drug discovery.

Bioinformatics approaches for cross-species liver cancer analysis based on microarray gene expression profiling

Background

The completion of the sequencing of human, mouse and rat genomes and knowledge of cross-species gene homologies enables studies of differential gene expression in animal models. These types of studies have the potential to greatly enhance our understanding of diseases such as liver cancer in humans. Genes co-expressed across multiple species are most likely to have conserved functions. We have used various bioinformatics approaches to examine microarray expression profiles from liver neoplasms that arise in albumin-SV40 transgenic rats to elucidate genes, chromosome aberrations and pathways that might be associated with human liver cancer.

Results

In this study, we first identified 2223 differentially expressed genes by comparing gene expression profiles for two control, two adenoma and two carcinoma samples using an F-test. These genes were subsequently mapped to the rat chromosomes using a novel visualization tool, the Chromosome Plot. Using the same plot, we further mapped the significant genes to orthologous chromosomal locations in human and mouse. Many genes expressed in rat 1q that are amplified in rat liver cancer map to the human chromosomes 10, 11 and 19 and to the mouse chromosomes 7, 17 and 19, which have been implicated in studies of human and mouse liver cancer. Using Comparative Genomics Microarray Analysis (CGMA), we identified regions of potential aberrations in human. Lastly, a pathway analysis was conducted to predict altered human pathways based on statistical analysis and extrapolation from the rat data. All of the identified pathways have been known to be important in the etiology of human liver cancer, including cell cycle control, cell growth and differentiation, apoptosis, transcriptional regulation, and protein metabolism.

Conclusion

The study demonstrates that the hepatic gene expression profiles from the albumin-SV40 transgenic rat model revealed genes, pathways and chromosome alterations consistent with experimental and clinical research in human liver cancer. The bioinformatics tools presented in this paper are essential for cross species extrapolation and mapping of microarray data, its analysis and interpretation.

Comparative molecular field analysis (CoMFA) model using a large diverse set of natural, synthetic and environmental chemicals for binding to the androgen receptor

A large number of natural, synthetic and environmental chemicals are capable of disrupting the endocrine systems of experimental animals, wildlife and humans. These so-called endocrine disrupting chemicals (EDCs), some mimic the functions of the endogenous androgens, have become a concern to the public health. Androgens play an important role in many physiological processes, including the development and maintenance of male sexual characteristics. A common mechanism for androgen to produce both normal and adverse effects is binding to the androgen receptor (AR). In this study, we used Comparative Molecular Field Analysis (CoMFA), a three-dimensional quantitative structure-activity relationship (3D-QSAR) technique, to examine AR-ligand binding affinities. A CoMFA model with r2 = 0.902 and q2 = 0.571 was developed using a large training data set containing 146 structurally diverse natural, synthetic, and environmental chemicals with a 10(6)-fold range of relative binding affinity (RBA). By comparing the binding characteristics derived from the CoMFA contour map with these observed in a human AR crystal structure, we found that the steric and electrostatic properties encoded in this training data set are necessary and sufficient to describe the RBA of AR ligands. Finally, the CoMFA model was challenged with an external test data set; the predicted results were close to the actual values with average difference of 0.637 logRBA. This study demonstrates the utility of this CoMFA model for real-world use in predicting the AR binding affinities of structurally diverse chemicals over a wide RBA range.

Size and shape of mineralites in young bovine bone measured by atomic force microscopy

Atomic force microscopy (AFM) was used to obtain three-dimensional images of isolated mineralites extracted from young postnatal bovine bone. The mean mineralite size is 9 nm x 6 nm x 2.0 nm, significantly shorter and thicker than the mineralites of mature bovine bone measured by the same technique. Mineralites of the young postnatal bone can be accommodated within the hole zone regions of a quasi-hexagonally packed collagen fibril in the fashion described by Hodge [9] in which laterally adjacent hole zone regions form continuous "channels" across the diameter of a fibril for a distance of at least 10 nm. Deposition of mineralites of the size noted above in this void volume of the fibrils would result in little or no distortion of the collagen molecules or supramolecular structure of the collagen fibril. The new AFM data supporting this claim is consistent with findings obtained by electron microscopy and low-angle x-ray and neutron diffraction that mineralites formed within collagen fibrils during initial stages of calcification occur within the hole zone region. However, the deposition of additional mineralites in the intermolecular spaces between collagen molecules in the overlap region of the fibrils would significantly distort the fibrils since the space available between adjacent molecules is considerably less than even the smallest dimension of the mineralites.

Regulatory application of SAR/QSAR for priority setting of endocrine disruptors: A perspective

Some seven years have passed since the U.S. legislature mandated the EPA to develop and implement a screening and testing program for chemicals that may disrupt the delicate endocrine system. The envisioned EPA program has evolved to incorporate a tiered scheme of in vitro and in vivo assays, and considered QSAR as a viable method to set testing priorities. At the U.S. FDA's National Center for Toxicological Research (NCTR), the Endocrine Disruptor Knowledge Base Project has developed models to predict estrogen and androgen receptor binding. Our approach rationally integrates various QSAR models into a sequential "Four-Phase" scheme according to the strength of each type of model. In four hierarchical phases, models predict the inactive chemicals that are then eliminated from the pool of chemicals to which increasingly precise but more time-consuming models are subsequently applied. Each phase employs different models selected to work complementarily in representing key activity-determining structure features in order to absolutely minimize the rate of false negatives, an outcome we view as paramount for regulatory use. In this paper, the QSAR models developed at NCTR, and particularly how we integrated these models into the "Four-Phase" system will be discussed for a number of datasets, including 58 000 chemicals identified by the U.S. EPA.

Phase I study of weekly oxaliplatin plus irinotecan in previously treated patients with metastatic colorectal cancer

BACKGROUND

In vitro synergy between Oxal (oxaliplatin) and CPT-11 (irinotecan) has been reported. Oxaliplatin exerts its antineoplastic activity through the formation of platinum-DNA adducts. Resistance to oxaliplatin is through repair of these adducts, which is inhibited by irinotecan.

PATIENTS AND METHODS

Oxaliplatin and irinotecan were administered weekly for 4 weeks followed by a 2-week rest period. The dose of oxaliplatin was escalated first, starting at 30 mg/m(2). Once a dose of 60 mg/m(2) was attained, the weekly dose of irinotecan was escalated, from 40 mg/m(2) to 85 mg/m(2). A total of 49 previously treated patients with metastatic colorectal cancer were entered in order to establish the maximum tolerated dose. Pharmacokinetics of oxaliplatin and irinotecan were analyzed.

RESULTS

Forty-nine patients were evaluable for toxicity. The recommended phase II doses for this combination are oxaliplatin 60 mg/m(2) and irinotecan 50 mg/m(2), weekly x 4 q 6 weeks. Diarrhea was the most common dose-limiting toxicity. No pharmacological interactions were noted between oxaliplatin and irinotecan. Twelve of the 47 evaluable patients (26%) achieved a partial response.

CONCLUSION

Weekly combination of oxaliplatin and irinotecan appears to be a well tolerated and active regimen in patients previously treated for metastatic colorectal cancer. Further investigations of this regimen are warranted.

An integrated "4-phase" approach for setting endocrine disruption screening priorities--phase I and II predictions of estrogen receptor binding affinity

Recent legislation mandates the US Environmental Protection Agency (EPA) to develop a screening and testing program for potential endocrine disrupting chemicals (EDCs), of which xenoestrogens figure prominently. Under the legislation, a large number of chemicals will undergo various in vitro and in vivo assays for their potential estrogenicity, as well as other hormonal activities. There is a crucial need for priority setting before this strategy can be effectively implemented. Here we report an integrated computational approach to priority setting using estrogen receptor (ER) binding as an example. This approach rationally integrates different predictive computational models into a "Four-Phase" scheme so that it can effectively identify potential estrogenic EDCs based on their predicted ER relative binding affinity (RBA). The system has been validated using an in-house ER binding assay dataset for 232 chemicals that was designed to have both broad structural diversity and a wide range of binding affinities. When applied to 58,000 chemicals identified by Walker et al. as candidates for endocrine disruption screening, some 9100 chemicals were predicted to bind to ER. Of these, only 3600 were expected to bind to ER at RBA values up to 100,000-fold less than that of 17beta-estradiol. The method ruled out 83% of the chemicals as non-binders with a very low rate of false negatives. We believe that the same integrated scheme will be equally applicable to endpoints of other endocrine disrupting mechanisms, e.g. androgen receptor binding.

Shape and size of isolated bone mineralites measured using atomic force microscopy

The inorganic phase of bone is comprised primarily of very small mineralites. The size and shape of these mineralites play fundamental roles in maintaining ionic homeostasis and in the biomechanical function of bone. Using atomic force microscopy, we have obtained direct three-dimensional visual evidence of the size and shape of native protein-free mineralites isolated from mature bovine bone. Approximately 98% of the mineralites are less than 2 nm thick displaying a plate-like habit. Distributions of both thickness and width show single peaks. The distribution of lengths may be multimodal with distinct peaks separated by approximately 6 nm. Application of our results is expected to be of use in the design of novel orthopaedic biomaterials. In addition, they provide more accurate inputs to molecular-scale models aimed at predicting the physiological and mechanical behavior of bone.

Rescue of the colony-stimulating factor 1 (CSF-1)-nullizygous mouse (Csf1(op)/Csf1(op)) phenotype with a CSF-1 transgene and identification of sites of local CSF-1 synthesis

Colony-stimulating factor 1 (CSF-1) regulates the survival, proliferation, and differentiation of mononuclear phagocytes. It is expressed as a secreted glycoprotein or proteoglycan found in the circulation or as a biologically active cell-surface glycoprotein. To investigate tissue CSF-1 regulation, CSF-1-null Csf1(op)/Csf1(op) mice expressing transgenes encoding the full-length membrane-spanning CSF-1 precursor driven by 3.13 kilobases of the mouse CSF-1 promoter and first intron were characterized. Transgene expression corrected the gross osteopetrotic, neurologic, weight, tooth, and reproductive defects of Csf1(op)/Csf1(op) mice. Detailed analysis of one transgenic line revealed that circulating CSF-1, tissue macrophage numbers, hematopoietic tissue cellularity, and hematopoietic parameters were normalized. Tissue CSF-1 levels were normal except for elevations in 4 secretory tissues. Skin fibroblasts from the transgenic mice secreted normal amounts of CSF-1 but also expressed some cell-surface CSF-1. Also, lacZ driven by the same promoter/first intron revealed beta-galactosidase expression in hematopoietic, reproductive, and other tissue locations proximal to CSF-1 cellular targets, consistent with local regulation by CSF-1 at these sites. These studies indicate that the 3.13-kilobase promoter/first intron confers essentially normal CSF-1 expression. They also pinpoint new cellular sites of CSF-1 expression, including ovarian granulosa cells, mammary ductal epithelium, testicular Leydig cells, serous acinar cells of salivary gland, Paneth cells of the small intestine, as well as local sites in several other tissues.

Phase transitions of hydroxyapatite coatings during post-heat treatment and their performances under ultrasonic tests

Highly or completely crystalline hydroxyapatite (HA) coatings can be obtained by post-heat treatment. We have developed a high-temperature (490 degrees C) and a low-temperature (125 degrees C) heat treatment to improve the crystallinity of HA coatings. Both methods transform entirely the amorphous phase into crystalline HA. However, the microstructure of the coating is dependent on the post-heating method. Nanocrystalline HA is about half of the component of the low-temperature heated coating while highly crystalline HA dominates the high-temperature heated coating, as detected by X-ray diffraction. The effects of both methods on the disintegration of the coatings were tested by ultrasonic treatment. The high-temperature heated coatings exhibited poor integrity while the low-temperature heated coatings exhibited better integrity, possibly due to their different microstructure. SEM revealed that the coatings disintegrated via different mechanisms: the high-temperature heated coatings failed via crack initiation and propagation while the low-temperature heated coatings failed via pit formation and subsequent widening.

Measurement of the bioactivity of interleukin and tumour necrosis factor in synovial fluid of Kashin-Beck disease

We studied the bioactivity of interleukin (IL-1) and tumour necrosis factor (TNF) in the synovial fluid of 12 patients with Kashin-Beck disease (KBD), 8 patients with osteoarthritis (OA) and 8 normal controls. C57 female mouse T cell proliferation method was used to test the bioactivity of IL-1, and lethality method with L929 cells to test the bioactivity of TNF. The bioactivities of IL-1 and TNF in the synovial fluid from patients with KBD were higher than those in the synovial fluid of osteoarthritis and normal controls, indicating the participation of IL-1 and TNF in the pathogenesis of KBD.

Phase I Study of Hepatic Arterial Infusion of Floxuridine and Dexamethasone With Systemic Irinotecan for Unresectable Hepatic Metastases From Colorectal Cancer

PURPOSE: To determine the maximum-tolerated dose (MTD) and dose-limiting toxicities of concurrent systemic irinotecan and hepatic arterial infusion (HAI) of floxuridine (FUDR) and dexamethasone in patients with unresectable hepatic metastases from colorectal cancer, to determine the safety of this combination in patients who have undergone cryosurgery, and to evaluate the pharmacokinetic effects of HAI FUDR on the metabolism of irinotecan.

PATIENTS AND METHODS: Forty-six previously treated patients with unresectable liver metastases and no known extrahepatic disease were treated concurrently with intravenous irinotecan weekly for 3 weeks and with HAI of FUDR and dexamethasone for 14 days (both were recycled in 28 days). Parallel cohorts of patients treated with or without cryosurgery were entered at escalating dose levels.

RESULTS: The MTD for patients who did not undergo cryosurgery was 100 mg/m2 of irinotecan weekly for 3 weeks every 4 weeks with concurrent HAI FUDR (0.16 mg/kg/d × pump volume/flow rate) plus dexamethasone for 14 days of a 28-day cycle. The dose-limiting toxicities were diarrhea and neutropenia. The response rate (complete and partial) among all patients who did not undergo cryosurgery was 74%. All patients in the cryosurgery group responded, and seven of the eight cryosurgery patients developed normal positron emission tomography scans after chemotherapy. HAI FUDR had no effect on the metabolism of irinotecan.

CONCLUSION: Combination therapy with HAI FUDR and dexamethasone plus systemic irinotecan may be safely administered to patients with unresectable hepatic metastases from colorectal cancer. The MTD has been reached for patients with unresectable disease, and we continue to investigate the MTD for patients who have undergone cryosurgery. Although the main objective of this study was to evaluate the toxicity of the combined regimen, a high response rate (74%) was observed.

Phase II study of the cyclin-dependent kinase inhibitor flavopiridol administered to patients with advanced gastric carcinoma

PURPOSE

Flavopiridol is the first cyclin-dependent kinase inhibitor to enter clinical trials. Activity in gastric cancer xenografts and in a patient with gastric cancer on the phase I trial led to this phase II study of flavopiridol in patients with metastatic gastric cancer.

PATIENTS AND METHODS

Sixteen patients were entered onto the study, and 14 were assessable for response. Flavopiridol was administered initially at a dose of 50 mg/m(2)/d by continuous infusion for 72 hours every 2 weeks. Assessment of plasma pharmacokinetics was performed in all patients. Peripheral mononuclear cells were collected throughout the 72-hour infusion for determinants of apoptosis.

RESULTS

There were no major objective responses (exact confidence interval 0% to 23%). One patient achieved a minor response in his liver metastases, though the primary progressed. Other patients exhibited histologic and radiographic evidence of tumor necrosis. Common toxicities included fatigue in 93% of patients (grade 3 or 4 in 27%) and diarrhea in 73% of patients (grade 3 or 4 in 20%). Five patients (33%) developed venous thromboses at the central catheter tip. The studies performed on peripheral mononuclear cells indicated no induction of apoptosis.

CONCLUSION

Flavopiridol administered as a single agent for 72 hours every 14 days is inactive in the treatment of gastric cancer. The drug also induced an unexpected higher incidence of vascular thrombosis and fatigue than was anticipated from the phase I trials. Future development of flavopiridol will depend on other doses and schedules in combination with chemotherapy.

Structure-activity relationships for a large diverse set of natural, synthetic, and environmental estrogens

Understanding structural requirements for a chemical to exhibit estrogen receptor (ER) binding has been important in various fields. This knowledge has been directly and indirectly applied to design drugs for human estrogen replacement therapy, and to identify estrogenic endocrine disruptors. This paper reports structure-activity relationships (SARs) based on a total of 230 chemicals, including both natural and xenoestrogens. Activities were generated using a validated ER competitive binding assay, which covers a 10(6)-fold range. This study is focused on identification of structural commonalities among diverse ER ligands. It provides an overall picture of how xenoestrogens structurally resemble endogenous 17beta-estradiol (E(2)) and the synthetic estrogen diethylstilbestrol (DES). On the basis of SAR analysis, five distinguishing criteria were found to be essential for xenoestrogen activity, using E(2) as a template: (1) H-bonding ability of the phenolic ring mimicking the 3-OH, (2) H-bond donor mimicking the17beta-OH and O-O distance between 3- and 17beta-OH, (3) precise steric hydrophobic centers mimicking steric 7alpha- and 11beta-substituents, (4) hydrophobicity, and (5) a ring structure. The 3-position H-bonding ability of phenols is a significant requirement for ER binding. This contributes as both a H-bond donor and acceptor, although predominantly as a donor. However, the 17beta-OH contributes as a H-bond donor only. The precise space (the size and orientation) of steric hydrophobic bulk groups is as important as a 17beta-OH. Where a direct comparison can be made, strong estrogens tend to be more hydrophobic. A rigid ring structure favors ER binding. The knowledge derived from this study is rationalized into a set of hierarchical rules that will be useful in guidance for identification of potential estrogens.

Inhaled aerosolization of all-trans-retinoic acid for targeted pulmonary delivery

Retinoids have shown promising activity for both cancer chemoprevention and as a treatment for emphysema. However, chronic oral administration of these drugs is limited by systemic side effects, including hepatic dysfunction, skeletal malformations, hyperlipidemia. hypercalcemia, and other reactions. In order to improve the pulmonary targeting of this potentially useful therapy, we developed a system for aerosolization of retinoids that substantially increased their local bioavailability. We compared the biodistribution and pharmacokinetics of an inhaled formulation of all-trans-retinoic acid (all-trans-RA), which was packaged in a metered dose inhaler, following both intratracheal (IT) and intravenous (IV) administration in male Sprague-Dawley rats. After drug administration, anesthetized animals were killed at 5 min, and at 1, 2, 4, 6 and 24 h. Plasma and emulsified samples of liver and lung tissues were dissected, extracted, and frozen prior to measurement of all-trans-RA concentration by high-performance liquid chromatography (HPLC). Aerosolization and IT injection of all-trans-RA resulted in a significantly longer pulmonary half-life of the drug (both 5-17 h), lower peak serum concentrations (aerosol 71 +/- 31 ng/ml, IT 68 +/- 50 ng/ml), and lower liver levels (aerosol 111 +/- 28 ng/g, IT 753 +/- 350 ng/g) than the same dose administered IV (2 h, 838 +/- 56 ng/ml, 4,258 +/- 1,006 ng/g, respectively; P < 0.05 for each comparison). Histologic examination of lungs and trachea showed no focal irritation attributable to the drug after single-dose administration. These results suggest that aerosolization of retinoids may offer a practical alternative to systemic oral administration for chemoprevention trials or treatment of lung diseases. This method may substantially increase the therapeutic index of these compounds by reducing systemic complications associated with long-term dosing.

Genetic evidence for the interactions of cyclin D1 and p27(Kip1) in mice

The cell cycle of cultured cells appears to be regulated by opposing actions of the cyclins together with their partners, the cyclin-dependent kinases (Cdk), and their inhibitors (Cki). Consistent with this situation null mutations in the genes for cyclin D1 and Cki p27(Kip1) in mice give opposite phenotypes of dwarfism and gigantism. To test their genetic interactions, we generated mice nullizygous for both genes. Correction of cyclin D1 or p27 null to wild-type phenotypes was observed for many but not all traits. These included, for cyclin D1(-/-) mice, body weight, early lethality, retinal hypoplasia, and male aggressiveness and, for p27(-/-) mice, body weight, retinal hyperplasia, and embryo implantation. p27(-/-) traits that were not corrected were the aberrant estrus cycles, luteal cell proliferation, and susceptibility to pituitary tumors. This mutual correction of these phenotypes is the first genetic demonstration of the interaction of these inhibitory and stimulatory cell cycle-regulatory molecules in vivo. The molecular basis for the correction was analyzed in the neonatal retina. Retinal cellularity was rescued in the cyclin D1 null mouse by loss of p27 with only a partial restoration of phosphorylation of retinoblastoma protein (Rb) and Cdk4 activity but with a dramatic elevation of Cdk2 activity. Our data provide in vivo genetic validation of cell culture experiments that indicated that p27 acts as a negative regulator of cyclin E-Cdk2 activity and that it can be titrated away by cyclin D-Cdk4 complexes. It also supports the suggestion that the cyclin E/Cdk2 pathway can largely bypass Rb in regulating the cell cycle in vivo.

Sugar coordinately and differentially regulates growth- and stress-related gene expression via a complex signal transduction network and multiple control mechanisms

In plants, sugars are required to sustain growth and regulate gene expression. A large set of genes are either up- or down-regulated by sugars; however, whether there is a common mechanism and signal transduction pathway for differential and coordinated sugar regulation remain unclear. In the present study, the rice (Oryza sativa cv Tainan 5) cell culture was used as a model system to address this question. Sucrose and glucose both played dual functions in gene regulation as exemplified by the up-regulation of growth-related genes and down-regulation of stress-related genes. Sugar coordinately but differentially activated or repressed gene expression, and nuclear run-on transcription and mRNA half-life analyses revealed regulation of both the transcription rate and mRNA stability. Although coordinately regulated by sugars, these growth- and stress-related genes were up-regulated or down-regulated through hexokinase-dependent and/or hexokinase-independent pathways. We also found that the sugar signal transduction pathway may overlap the glycolytic pathway for gene repression. alpha-Amylase and the stress-related genes identified in this study were coordinately expressed under sugar starvation, suggesting a convergence of the nutritional and environmental stress signal transduction pathways. Together, our studies provide a new insight into the complex signal transduction network and mechanisms of sugar regulation of growth and stress-related genes in plants.

Paclitaxel, estramustine phosphate, and carboplatin in patients with advanced prostate cancer

PURPOSE

To determine the safety and activity of weekly paclitaxel in combination with estramustine and carboplatin (TEC) in patients with advanced prostate cancer.

PATIENTS AND METHODS

In a dose-escalation study, patients with advanced prostate cancer were administered paclitaxel (weekly 1-hour infusions of 60 to 100 mg/m(2)), oral estramustine (10 mg/kg), and carboplatin (area under the curve, 6 mg/mL-min every 4 weeks). Paclitaxel levels were determined 0, 30, 60, 90, and 120 minutes and 18 hours after infusion, and a concentration-time curve was estimated. Once a safe dose was established, a multi-institutional phase II trial was conducted in patients with progressive androgen-independent disease.

RESULTS

Fifty-six patients with progressive androgen-independent disease were treated for a median of four cycles. The dose of paclitaxel was escalated from 60 to 100 mg/m(2) without the occurrence of DLT. Posttherapy decreases in serum prostate-specific antigen levels of 50%, 80%, and 90% were seen in 67%, 48%, and 39% (95% confidence interval, 55% to 79%, 35% to 61%, 26% to 52%) of the patients, respectively. Of the 33 patients with measurable disease, two (6%) had a complete response and 13 (39%) had a partial response. The overall median time to progression was 21 weeks, and the median survival time for all patients was 19.9 months. Major grade 3 or 4 adverse effects were thromboembolic disease (in 25% of patients), hyperglycemia (in 38%), and hypophosphatemia (in 42%). Significant leukopenia, thrombocytopenia, and peripheral neuropathy were not observed.

CONCLUSION

TEC has significant antitumor activity and is well tolerated in patients with progressive androgen-independent prostate cancer.

QSAR models using a large diverse set of estrogens

Endocrine disruptors (EDs) have a variety of adverse effects in humans and animals. About 58,000 chemicals, most having little safety data, must be tested in a group of tiered assays. As assays will take years, it is important to develop rapid methods to help in priority setting. For application to large data sets, we have developed an integrated system that contains sequential four phases to predict the ability of chemicals to bind to the estrogen receptor (ER), a prevalent mechanism for estrogenic EDs. Here we report the results of evaluating two types of QSAR models for inclusion in phase III to quantitatively predict chemical binding to the ER. Our data set for the relative binding affinities (RBAs) to the ER consists of 130 chemicals covering a wide range of structural diversity and a 6 orders of magnitude spread of RBAs. CoMFA and HQSAR models were constructed and compared for performance. The CoMFA model had a r2 = 0.91 and a q2LOO = 0.66. HQSAR showed reduced performance compared to CoMFA with r2 = 0.76 and q2LOO = 0.59. A number of parameters were examined to improve the CoMFA model. Of these, a phenol indicator increased the q2LOO to 0.71. When up to 50% of the chemicals were left out in the leave-N-out cross-validation, the q2 remained significant. Finally, the models were tested by using two test sets; the q2pred for these were 0.71 and 0.62, a significant result which demonstrates the utility of the CoMFA model for predicting the RBAs of chemicals not included in the training set. If used in conjunction with phases I and II, which reduced the size of the data set dramatically by eliminating most inactive chemicals, the current CoMFA model (phase III) can be used to predict the RBA of chemicals with sufficient accuracy and to provide quantitative information for priority setting.

Fragmentation of N-oxides (deoxygenation) in atmospheric pressure ionization: investigation of the activation process

The diagnostic fragmentation of N-oxides resulting from loss of the oxygen atom (MH+ --> MH+-O) in electrospray and atmospheric pressure chemical ionization (APCI) mass spectra was investigated. When the temperature of the heated capillary tube was elevated, the ratio of the intensity of the [MH+ -16] fragment to the precursor ion (MH+) increased. This 'deoxygenation' process was associated with thermal activation and did not result from collisional activation in the desolvation region of the API source. Although the extent of 'deoxygenation' is compound-dependent, it can provide evidence for the presence of an N-oxide in a sample and can be used to distinguish N-oxides from hydroxylated metabolites (Ramanathan et al. Anal. Chem. 2000; 72: 1352). To demonstrate the practical application of thermal fragmentation of N-oxides, liquid chromatography (LC)/APCI-MS was used to distinguish an N-oxide drug from its hydroxylated metabolite in an unprocessed rat urine sample, despite the fact that the drug and its metabolite were not fully resolved by HPLC.

Huanglian, A chinese herbal extract, inhibits cell growth by suppressing the expression of cyclin B1 and inhibiting CDC2 kinase activity in human cancer cells

Huanglian is an herb that is widely used in China for the treatment of gastroenteritis. We elected to determine whether huanglian could inhibit tumor cell growth by modulating molecular events directly associated with the cell cycle. Huanglian inhibited tumor growth and colony formation of gastric, colon, and breast cancer cell lines in a time- and dose-dependent manner. Cell growth was completely inhibited after 3 days of continuous drug exposure to 10 microg/ml of herb. This degree of growth inhibition was significantly greater than that observed with berberine, the major constituent of the herb. The inhibition of cell growth by huanglian was associated with up to 8-fold suppression of cyclin B1 protein. This resulted in complete inhibition of cdc2 kinase activity and accumulation of cells in G(2). The mRNA expression of cyclin B1 was not changed after huanglian treatment. There was no change in the protein expression of cyclins A or E. Therefore, the effect of huanglian on inhibiting tumor growth seems to be mediated by the selective suppression of cyclin B1, which results in the inhibition of cdc2 kinase activity. Inhibition of cyclin dependent kinase (cdk) activity is emerging as an attractive target for cancer chemotherapy. Huanglian represents a class of agents that can inhibit tumor cell growth by directly suppressing the expression of a cyclin subunit that is critical for cell cycle progression. These results indicate that traditional Chinese herbs may represent a new source of agents designed for selective inhibition of cyclin dependent kinases in cancer therapy.

Rationalised prescribing for community acquired pneumonia: a closed loop audit

AIMS

To audit the management of community acquired pneumonia before and after the introduction of a protocol. To determine the aetiology of pneumonia using routine investigations and polymerase chain reaction (PCR).

METHODS

Retrospective and prospective audit following the introduction of a management protocol. Prospective cases were investigated routinely and with PCR on blood and nasopharyngeal aspirate.

RESULTS

There was a significant increase in rational prescribing following introduction of the protocol with 75% of children receiving intravenous penicillin or erythromycin compared with 26% beforehand. Of 89 children in the prospective group, 51 microbiological diagnoses were achieved in 48 children. Seven children had Streptococcus pneumoniae infection, 14 had Mycoplasma infection, six had pertussis, and one had Chlamydia pneumoniae infection. Twenty three children had a viral cause of which respiratory syncytial virus was commonest.

CONCLUSIONS

Introduction of the protocol led to improved prescribing. PCR increased the diagnostic yield and the results support the management protocol.

Heat shock proteins' mRNA expression in asthma

OBJECTIVE

The aim of the present study was to investigate the expression levels of heat shock proteins (HSP) mRNA in the peripheral blood mononuclear cells (PBMC) of patients with asthma and chronic bronchitis to elucidate the role of HSP in the pathogenesis of asthma and chronic bronchitis.

METHOD

Using reverse transcription-DNA polymerase chain reaction, the expression levels of HSP70, HSP90alpha and HSP90beta genes in PBMC in normal state and after heat shock were investigated.

RESULTS

No HSP70 gene but HSP90alpha and HSP90beta expressions were found in non-heat-shocked PBMC of normal controls; HSP90alpha and HSP90beta genes may be expressed in PBMC of all patients, independently of acute episodes. Expression of HSP70 was found in PBMC of asthmatic patients in acute episodes and three symptom-free patients with Aas 3, step 2. Among patients with chronic bronchitis, no HSP70 gene expression was found in PBMC of patients in convalescent period but in PBMC of patients in acute episode. HSP90alpha and HSP90beta genes were expressed in PBMC of both patient groups. After heat shock, expressions of the three genes increased significantly in PBMC of both normal controls and patients.

CONCLUSION

Expression of HSP70 gene in PBMC of asthmatic and chronic bronchitis patients was different, indicating that HSP, especially HSP70, might be involved in the pathogenesis of asthma.

Phase I and pharmacokinetic study of 10-propargyl-10-deazaaminopterin, a new antifolate

The 10-deazaaminopterins are a new class of rationally designed antifolates demonstrating greater antitumor effects than methotrexate in murine tumor models and human tumor xenografts. Their design was aimed at improving membrane transport and polyglutamylation in tumor cells, resulting in increased intracellular accumulation and enhanced cytotoxicity. Compared with other 4-aminofolate analogues, 10-propargyl-10-deazaaminopterin (PDX) is the most efficient permeant for the RFC-1-mediated internalization and substrate for folylpolyglutamate synthetase. PDX demonstrates greater in vitro and in vivo antitumor efficacy than methotrexate or edatrexate. We undertook a Phase I study with PDX to identify the potential toxicities and define an optimal dose and schedule. Thirty-three patients were enrolled, all of whom had non-small cell lung cancer (NSCLC) and were treated previously with a median of two prior chemotherapy regimens. Initially, PDX was administered weekly for 3 weeks in a 4-week cycle. Mucositis requiring dose reduction and/or delay in the first cycle occurred in four of six patients treated at the initial dose level (30 mg/m2), making this the maximal tolerated dose for PDX given on this schedule. The treatment schedule was then modified to every 2 weeks. Twenty-seven patients were treated twice weekly with a total of 102 four-week cycles (median, 2 cycles/patient). Mucositis was the dose-limiting toxicity, with grade 3 and 4 mucositis occurring in the first two patients treated at the 170 mg/m2 dose level. Other toxicities were mild and reversible. No neutropenia was observed. The recommended Phase II dose is 150 mg/m2 biweekly. At that dose level, the mean area under the curve was 20.6 micromol x h, and the mean terminal half-life was 8 h. Two patients with stage IV NSCLC had major objective responses, and five patients had stable disease for 7 (two patients), 9 (one patient), 10 (one patient), and 13 months (one patient). PDX is a new antifolate with manageable toxicity and evidence of antitumor activity in NSCLC. A Phase II trial in NSCLC and a Phase I trial with paclitaxel are under way. These studies will also quantitate the expression of genes controlling internalization (RFC-1) and polyglutamylation of PDX in tumor cells as correlates of response.

Quantitative comparisons of in vitro assays for estrogenic activities

Substances that may act as estrogens show a broad chemical structural diversity. To thoroughly address the question of possible adverse estrogenic effects, reliable methods are needed to detect and identify the chemicals of these diverse structural classes. We compared three assays--in vitro estrogen receptor competitive binding assays (ER binding assays), yeast-based reporter gene assays (yeast assays), and the MCF-7 cell proliferation assay (E-SCREEN assay)--to determine their quantitative agreement in identifying structurally diverse estrogens. We examined assay performance for relative sensitivity, detection of active/inactive chemicals, and estrogen/antiestrogen activities. In this examination, we combined individual data sets in a specific, quantitative data mining exercise. Data sets for at least 29 chemicals from five laboratories were analyzed pair-wise by X-Y plots. The ER binding assay was a good predictor for the other two assay results when the antiestrogens were excluded (r(2) is 0.78 for the yeast assays and 0.85 for the E-SCREEN assays). Additionally, the examination strongly suggests that biologic information that is not apparent from any of the individual assays can be discovered by quantitative pair-wise comparisons among assays. Antiestrogens are identified as outliers in the ER binding/yeast assay, while complete antagonists are identified in the ER binding and E-SCREEN assays. Furthermore, the presence of outliers may be explained by different mechanisms that induce an endocrine response, different impurities in different batches of chemicals, different species sensitivity, or limitations of the assay techniques. Although these assays involve different levels of biologic complexity, the major conclusion is that they generally provided consistent information in quantitatively determining estrogenic activity for the five data sets examined. The results should provide guidance for expanded data mining examinations and the selection of appropriate assays to screen estrogenic endocrine disruptors.

[A preliminary study of viral cross-transmission in dentistry]

OBJECTIVE

To research the viral cross-transmission of a DNA virus (HBV) and a RNA virus (HCV) in dentistry.

METHODS

Five plans were designed to sterilize the oral instruments that had been infected with HBV or HCV positive serum. HBsAg, HBV-DNA, anti-HCV, HCV-RNA were detected before and after sterilization.

RESULTS

All methods could effectively clean the specific proteins (HBsAg/anti-HCV) and nucleic acids (HBV-DNA/HCV-RNA) of the infected virus.

CONCLUSION

The instruments which have been sterilized should not be the main way of the cross-transmission of virus in dentistry.

[Persistence of hepatitis C virus type II in patient's peripheral blood B lymphocytes transformed by Epstein-Barr virus]

OBJECTIVE

To study the persistence and replication of hepatitis C virus (HCV)-RNA in human peripheral blood B cells transformed by Epstein-Barr virus (EBV) and cultured in vitro.

METHODS

EBV was used for infecting B lymphocytes from one hepatitis C patient with HCV positive in the peripheral blood mononuclear cells (PBMC) and transforming them into lymphoblasts capable of being propagated indefinitely. Then, HCV RNA of the cultured cells and supernatants was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) every one month. HCV gene was typed by enzyme separating method. Electron microscopy and immunoelectron microscopy were employed to locate HCV in the cells and observe the character of its configuration.

RESULTS

HCV positive-strand RNA was detected in the cultured cells for 1 year. Interestingly, the HCV positive-strand RNA was identified in supernatants and the negative-strand RNA was also observed in the cultured cells intermittently. HCV gene was type II. Electron microscopy observed HCV spherical virus-like particles with a diameter of approximately 45 nm to 70 nm, individual particles 110 nm, in the LCL cytoplasmic vesicles.

CONCLUSION

HCV may exist in the cultured cell line for a longer period and reproduce in and secrete out of them. HCV locates mainly in the cytoplasm. The cell line might be useful in analyzing the mechanisms of HCV persistence in PBMC.