O4 Neural network image capture to predict response of oesophageal adenocarcinoma to neoadjuvant therapy

Introduction

Locally advanced oesophageal adenocarcinoma is typically treated with neoadjuvant chemotherapy (NACT) or chemoradiotherapy (NACRT) followed by surgery. Significant benefit to neoadjuvant treatment however is confined to a minority of patients (<25%) and there are no reliable means of establishing prior to treatment in whom this benefit will occur. In this study, we assessed the utility of features extracted from high-resolution digital microscopy of pre-treatment biopsies in predicting response to neoadjuvant therapy in a machine-learning based modelling framework.

Method

A total of 102 cases were included in the study. Pre-treatment clinical information, including TNM staging, was obtained, along with diagnostic biopsies. Diagnostic biopsies were converted into high-resolution whole slide-images and features extracted using a pre-trained convolutional neural network (Xception). Elastic net regression models were then trained and validated with bootstrapping with 1000 resampled datasets. The response was considered according to Mandard tumour regression grade (TRG).

Result

There were 45 (44.1%) responders (TRG1-2) and 57 (57%) non-responders (TRG3-5) in the dataset. 34 patients (33.3%) received NACT and 68 (66.7%) received NACRT. A model trained with RNA-seq data achieved fair performance only in predicting response (AUC 0.598 95% CI 0.593–0.603), which was far exceeded by use of segmented diagnostic biopsy images (AUC 0.872 95% CI 0.869–0.875), which also produced well calibrated predictions of risk.

Conclusion

Despite using a small dataset, impressive performance in classifying response to neoadjuvant treatment can be achieved, particularly using automated image classification. Further study to refine the methodology is required before expansion to clinical settings.

Take-home Message

Response to neoadjuvant treatment for oesophageal cancer can be predicted from diagnostic biopsies

Spirocycle MmpL3 Inhibitors with Improved hERG and Cytotoxicity Profiles as Inhibitors of Mycobacterium tuberculosis Growth

With the emergence of multi-drug-resistant strains of Mycobacterium tuberculosis, there is a pressing need for new oral drugs with novel mechanisms of action. A number of scaffolds with potent anti-tubercular in vitro activity have been identified from phenotypic screening that appear to target MmpL3. However, the scaffolds are typically lipophilic, which facilitates partitioning into hydrophobic membranes, and several contain basic amine groups. Highly lipophilic basic amines are typically cytotoxic against mammalian cell lines and have associated off-target risks, such as inhibition of human ether-à-go-go related gene (hERG) and IKr potassium current modulation. The spirocycle compound 3 was reported to target MmpL3 and displayed promising efficacy in a murine model of acute tuberculosis (TB) infection. However, this highly lipophilic monobasic amine was cytotoxic and inhibited the hERG ion channel. Herein, the related spirocycles (1-2) are described, which were identified following phenotypic screening of the Eli Lilly corporate library against M. tuberculosis. The novel N-alkylated pyrazole portion offered improved physicochemical properties, and optimization led to identification of a zwitterion series, exemplified by lead 29, with decreased HepG2 cytotoxicity as well as limited hERG ion channel inhibition. Strains with mutations in MmpL3 were resistant to 29, and under replicating conditions, 29 demonstrated bactericidal activity against M. tuberculosis. Unfortunately, compound 29 had no efficacy in an acute model of TB infection; this was most likely due to the in vivo exposure remaining above the minimal inhibitory concentration for only a limited time.

1341. Development of a Series of High-Throughput Screens to Identify Leads for Nontuberculous Mycobacteria Drug Design

Background

Nontuberculous mycobacteria (NTM), particularly Mycobacterium avium complex and Mycobacterium abscessus complex, cause significant morbidity and mortality in patients with impaired host immunity or pre-existing structural lung conditions. NTM infections are increasing at an alarming rate worldwide and there is a dearth of progress in regard to the development of efficacious and tolerable drugs to treat such infections. Traditional drug discovery screens do not account for the diverse physiological conditions, microenvironments, and compartments that the bacilli encounter during human infection. In order to help populate the NTM drug pipeline, and explore the disconnect between in vitro activity, in vivo activity, and clinical outcomes, we are developing a high throughput in vitro assay platform that will more closely model the unique infection-relevant conditions encountered by NTM.

Methods

We are developing and validating a suite of in vitro assays that screen compounds for activity against extracellular planktonic bacteria, extracellular bacteria within biofilms, intracellular bacteria, and nutrient-starved non-replicating bacteria.

Results

We are using both the smooth and rough morphotypes of M. abscessus and M. avium. We have validated high throughput assays to pharmaceutical standards for replicating and non-replicating M. abscessus. We have also tested a panel of 18 known anti-mycobacterial compounds. Assay development is currently underway to test compounds for activity against NTM in biofilm and inside macrophages as well.

Conclusion

To enhance hit identification for scaffolds to use as starting points for NTM drug development, focused libraries of compounds that have undergone significant preclinical profiling and/or compounds with known activity against M. tuberculosis (TB) will be screened. Such a “piggyback” approach usurps advances made in TB drug development and leverages them for NTM drug discovery. This will help expedite novel drug development, reduce attrition rate, and offer a shorter route to clinical use as it exploits the prior investment in medicinal chemistry, pharmacology, and toxicology.

Disclosures

All authors: No reported disclosures.

Anthranilic amide and imidazobenzothiadiazole compounds disrupt Mycobacterium tuberculosis membrane potential

Compounds 1 and 2 disrupt M. tuberculosis membrane potential and demonstrate bactericidal activity against non-replicating M. tuberculosis in pH 4.5 buffer.

A family of compounds typified by an anthranilic amide 1 was identified from a whole-cell screening effort targeted at identifying compounds that disrupt pH homeostasis in Mycobacterium tuberculosis. 1 demonstrated bactericidal activity against non-replicating M. tuberculosis in pH 4.5 buffer (MBC_4.5 = 6.3 μM). Exploration of the structure–activity relations failed to simplify the scaffold. The antitubercular activity proved dependent on the lipophilicity and planarity of the molecule and directly correlated with mammalian cytotoxicity. Further studies revealed a pH-dependent correlation between the family's disruption of M. tuberculosis membrane potential and antitubercular activity, with active compounds causing a drop in membrane potential at concentrations below their MBC_4.5. A second compound family, identified in the same screening effort and typified by imidazo(4,5-e)(2,1,3)benzothiadiazole 2, provided a contrasting profile. As with 1, structure–activity profiling of 2 (MBC_4.5 = 25 μM) failed to minimize the initial scaffold, mammalian cytotoxicity was observed for a majority of the active compounds, and many of the active compounds disrupted M. tuberculosis membrane potential. However, unlike the anthranilic amide compounds, the benzothiadiazole compounds disrupted M. tuberculosis membrane potential primarily at concentrations above the MBC_4.5 in a pH-independent fashion. These differences suggest an alternative mechanism of action for the benzothiadiazole compounds. As a result, while the cytotoxicity of the anthranilic amides limits their utility to tool compounds, benzothiadiazole 2 presents an attractive target for more focused SAR exploration.

Identification of Compounds with pH-Dependent Bactericidal Activity against Mycobacterium tuberculosis

To find new inhibitors of Mycobacterium tuberculosis that have novel mechanisms of action, we miniaturized a high throughput screen to identify compounds that disrupt pH homeostasis. We adapted and validated a 384-well format assay to determine intrabacterial pH using a ratiometric green fluorescent protein. We screened 89000 small molecules under nonreplicating conditions and confirmed 556 hits that reduced intrabacterial pH (below pH 6.5). We selected five compounds that disrupt intrabacterial pH homeostasis and also showed some activity against nonreplicating bacteria in a 4-stress model, but with no (or greatly reduced) activity against replicating bacteria. The compounds selected were two benzamide sulfonamides, a benzothiadiazole, a bissulfone, and a thiadiazole, none of which are known antibacterial agents. All of these five compounds demonstrated bactericidal activity against nonreplicating bacteria in buffer. Four of the five compounds demonstrated increased activity under low pH conditions. None of the five compounds acted as ionophores or as general disrupters of membrane potential. These compounds are useful starting points for work to elucidate their mechanism of action and their utility for drug discovery.

The future for early-stage tuberculosis drug discovery

There is an urgent need for new and better drugs to treat tuberculosis due to lengthy and complex treatment regimens and a rising problem of drug resistance. Drug discovery efforts have increased over the past few years, with a larger focus on modern high-throughput screening technologies. A combination of target-based approaches, with the traditional empirical means of drug identification, has been complemented by the use of target-based phenotypic screens only recently made possibly with newer genetic tools. Using these approaches, a number of promising compound series have been discovered. However, significant problems remain in developing these into drugs. This review highlights recent advances in TB drug discovery, including an overview of screening campaigns, lessons learned and future directions.

Determination of compound kill kinetics against Mycobacterium tuberculosis

In this chapter, we describe how to determine the kill kinetics and minimum bactericidal concentration (MBC) of a compound against Mycobacterium tuberculosis. Techniques are described for three conditions: actively growing aerobic bacteria, and non-replicating bacteria induced by nutrient starvation and/or low pH. Each technique involves determining the number of viable bacteria in the presence of several concentrations of compound over 3 weeks. Guidelines for how to interpret the results, to determine if growth-inhibitory compounds are bactericidal or bacteriostatic and also whether compounds exhibit time-dependent or concentration-dependent kill are provided.

Synthesis and evaluation of the 2,4-diaminoquinazoline series as anti-tubercular agents

The 2,4-diaminoquinazoline class of compounds has previously been identified as an effective inhibitor of Mycobacterium tuberculosis growth. We conducted an extensive evaluation of the series for its potential as a lead candidate for tuberculosis drug discovery. Three segments of the representative molecule N-(4-fluorobenzyl)-2-(piperidin-1-yl)quinazolin-4-amine were examined systematically to explore structure-activity relationships influencing potency. We determined that the benzylic amine at the 4-position, the piperidine at 2-position and the N-1 (but not N-3) are key activity determinants. The 3-deaza analog retained similar activity to the parent molecule. Biological activity was not dependent on iron or carbon source availability. We demonstrated through pharmacokinetic studies in rats that good in vivo compound exposure is achievable. A representative compound demonstrated bactericidal activity against both replicating and non-replicating M. tuberculosis. We isolated and sequenced M. tuberculosis mutants resistant to this compound and observed mutations in Rv3161c, a gene predicted to encode a dioxygenase, suggesting that the compound may act as a pro-drug.

Mycobacterium avium uses apoptotic macrophages as tools for spreading

BACKGROUND

Mycobacterium avium (MAC) lives and replicates in macrophages and causes disseminated disease in immunocompromised individuals. As a host response to control disease, many macrophages become apoptotic a few days after MAC infection. In this study, we hypothesized that MAC can survive autophagic and apoptotic macrophages and spread.

METHODS

Electron, time-lapse video, fluorescence microscopy. Apoptosis was determined by ELISA and TUNEL assays. Autophagy was seen by migration of LC3-1.

RESULTS

Apoptotic macrophages harbor chiefly viable MAC. MAC escapes both the vacuole and the macrophage once apoptosis is triggered, leaving the bacteria free to infect nearby macrophages in the process of spreading. In addition, some MAC species will have apoptotic bodies and are released in healthy macrophages following apoptotic body ingestion. Because autophagy precedes apoptosis, it was established that heat-killed MAC, and viable MAC induces autophagy in macrophages at similar rates, but MAC still survives.

CONCLUSION

MAC spreading from cell-to-cell is triggered by the macrophage's attempt to kill the bacterium, undergoing apoptosis.

Housing characteristics of farmworker families in North Carolina

Adequate housing is a basic human right and an important determinant of environmental health. Little research has documented the housing quality of immigrant Latino farmworker families. This analysis uses data from four surveys of North Carolina farmworker communities conducted in 2001 and 2003 to document aspects of housing quality that could affect farmworker family health. Three housing domains are considered: dwelling characteristics, household characteristics, and household behaviors. Most farmworker families live in mobile homes, and few own their dwellings. Many are located near agricultural fields. Most houses are small, but household size is large, containing adults, in addition to the nuclear family. Crowding is common among farmworker families. Many farmworker households lack basic facilities, such as washing machines. Farmworkers attempt to reduce exposure by frequently cleaning their dwellings. These findings suggest that the health of farmworker families is at risk due to inadequate housing. Further research on housing-related health effects among farmworker families is needed.

Review of pesticide education materials for health care providers providing care to agricultural workers

CONTEXT

Pesticide exposure is an important environmental and occupational health risk for agricultural workers and their families, but health care providers receive little training in it.

OBJECTIVE

To evaluate the medical resources available to providers caring for patients, particularly farmworkers, exposed to pesticides and to recommend a selective bibliography for use in educating clinicians about pesticides and health care. These resources are divided into 3 domains: (1) the working knowledge, (2) the skill set, and (3) the references needed to care for these patients.

METHODS

We searched library databases dating back to 1995, as well as conference materials and Internet resources. Materials were included only if they were readily available through customary sources. Materials were randomly divided into 2 groups. Two authors wrote detailed reviews for each group. The remaining authors read each document and review, making changes that were agreed upon by the team. Review procedures were standardized to examine the contemporary relevance, quality, and overall strengths and weaknesses of the material relative to guidelines developed for each domain. These guidelines were developed from the authors' experience, national focus groups, and literature review.

RESULTS

While no 1 resource adequately addresses all needs, a number of resources were identified addressing the categories of working knowledge, skill set, and reference materials. Few of the reviewed materials address the cultural competence of providers treating farmworkers. Additional education resources are needed.

Neurobehavioral performance in preschool children from agricultural and non-agricultural communities in Oregon and North Carolina

Organophosphate (OP) pesticides produce acute toxic effects but little is known about low-level chronic exposures. Latino children of agricultural workers have a high risk of exposure to pesticides because of the close proximity of their homes to fields where pesticides are applied and from take-home exposure. Neurobehavioral performance of preschool children from agricultural (AG) communities was compared to performance of those from non-agricultural (Non-AG) communities in Oregon and North Carolina. Seventy-eight children aged 48-71 months completed a battery of neurobehavioral tests two times, approximately 1 month apart. Multiple regression revealed that the AG children performed poorer on measures of response speed (Finger Tapping) and latency (Match-to-Sample) compared to the Non-AG children. These results demonstrate modest differences in AG children compared to Non-AG children that are consistent with functional effects seen in adults exposed to low concentrations of OP pesticides. Just as was the case following early research on adults poisoned by pesticides, this study points to the need for additional investigations to test the hypothesis that low-concentration OP exposures affect acquisition of test performance, response speed and latency in children of agricultural workers.

Household food security among migrant and seasonal latino farmworkers in North Carolina

OBJECTIVE

Food insecurity is defined as lack of access at all times, due to economic barriers, to enough food for an active and healthy lifestyle. The objective of this study was threefold: to characterize levels of food security, food insecurity, and hunger among migrant and seasonal Latino farmworkers; to assess predictors of food insecurity for this group; and to describe the strategies farmworkers use to cope with food insecurity.

METHODS

Adults from 102 farmworker households in North Carolina responded to a survey that used a Spanish-language adaptation of the U.S. Household Food Security Survey Module and questions about sociodemographic characteristics and food behaviors. Twenty-five farmworkers participated in in-depth interviews in which they described their households' food security situation and coping strategies.

RESULTS

Forty-eight of the 102 sample households (47.1%) were classified as food insecure, including 10 (9.8%) with moderate hunger and five (4.9%) with severe hunger. Households with children had a significantly higher prevalence of food insecurity than those without children (56.4% vs. 36.2%). Households with children accessed food programs such as the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) that were unavailable to those without children, while those without children were more likely to access food pantries and to consume wild game or fish. Coping strategies included borrowing money, reducing food variety, and adults consuming less food to protect children from hunger. Food insecurity was more than four times as prevalent among farmworker households as among the general U.S. population.

CONCLUSION

Policy changes to increase economic resources and access to federal programs are needed to decrease this food insecurity.

Structure-activity relationship of alkyl camptothecin esters

The cytotoxicity of camptothecin (CPT) esters 1-6 was measured. Like parental camptothecin, esters 2 and 3, but not 1, 4, 5, and 6, inhibited proliferation of human leukemia cells in culture and induced programmed cell death as assessed by flow cytometry studies. Exhibition of similar levels of antiproliferative activities of CPT 2 and 3 required different incubation time periods in cell cultures, with CPT and 3 requiring the shortest and longest periods, respectively. Both 2 and 3 were inactive against cells resistant to the semisynthetic CPT derivative 9-nitrocamptothecin and unable to stabilize DNA-topoisomerase I (Topo I) "cleavable complexes" in a cell-free system, suggesting that Topo I activity was required but insufficient for the mechanism of action of 2 and 3. Mouse liver homogenate converted esters to parental CPT, but the conversion rates were different with different esters. Of four tested esters in this experiment, ester 2 had the fastest conversion rate. In vivo studies showed that ester 2 had an exceptional lack of toxicity in nude mice, even at enormous doses, and demonstrated extensive activity against human breast and colon tumors grown as xenografts in immunodeficient nude mice, whereas no antitumor activity was observed for the other esters. In conclusion, ester 2 is a prodrug of the antitumor compound CPT, and it can be administered at very high doses in mice with no appearance of toxicity. This study provides a basis for further evaluation of CPT ester 2 as an investigational anticancer agent.

Altered sensitivities to anticancer and differentiation agents in etoposide-resistant human myeloid leukemia U-937 cells

We previously have exposed U-937 human leukemia cells to stepwise increased concentrations of the anticancer drug etoposide, and this treatment has resulted in stable sublines (termed U-937/RE) exhibiting various extents of resistance to the drug and constitutively expressing c-fms mRNA, a specific marker of monocytic differentiation. In this report, we pursued studies to show that the P-glycoprotein blocker, verapamil, partially restores sensitivity to etoposide in U-937/RE cells. Further, the U-937/RE cells exhibit differential sensitivities to compounds that induce maturation of U-937 cells, as judged by the ability to reduce nitroblue tetrazolium and by morphologic changes, and increased sensitivities to apoptosis induction by the cytokines tumor necrosis factor (TNF) and lymphotoxin (LT) and the anticancer drugs 9-nitrocamptothecin and doxorubicin. In addition, the U-937/RE cells, xenografted in immunodeficient mice, demonstrate decreased or no ability to induce tumors. Taken together, these findings indicate that U-937/RE cells differ from the parental U-937 cells in several functional properties and can serve as models to develop protocols for treatment of human leukemia.

Effect of variations in calcaneocuboid fusion technique on kinematics of the normal hindfoot

Calcaneocuboid fusion with lengthening of the lateral column of the foot has been advocated as a method of treating flatfoot deformity. This study was designed to determine how the length of the lateral column chosen or the position of the foot selected when performing this fusion affect hindfoot kinematics in normal cadaver feet. An electromagnetic tracking system was used to monitor the positions of the talus, calcaneus, navicular, and cuboid while the intact cadaver feet were moved passively and then under reproducible loads. Calcaneocuboid fusion was then performed on these feet first with the feet in neutral position and the lateral column of normal length, then lengthened 10 mm or shortened 5 mm, and then with the lateral column lengthened 10 mm and the feet positioned in plantar flexion and eversion or dorsiflexion and inversion. Kinematic measurements were made at each stage using the same loads. Fusing the calcaneocuboid joint with lengthening or shortening the lateral column and the feet in neutral position did not affect hindfoot joint motion compared with intact. Changing the position of the foot for fusion, however, resulted in significant decreases in motion in the talocalcaneal and talonavicular joints. Tibiotalar joint motion was unaffected. This study, therefore, demonstrates that when fusing the calcaneocuboid joint, attention should be paid to maintaining a neutral position of the foot.

Establishment of human prostate tumor xenografts in nude mice and response to 9-nitrocamptothecin in vivo and in vitro does not correlate with the expression of various apoptosis-regulating proteins

Flow cytometry and microscopy analyses have demonstrated that 9-nitrocamptothecin (9NC) induces apoptosis in prostate carcinoma LNCaP, DU-145 and PC-3 cells grown in culture or as xenografts. 9NC induces apoptosis regardless of the ability of the cells to induce tumors following xenografting into nude mice. Detection of apoptosis by flow cytometry was preceded or accompanied by increased cell size, loss of nuclear structure and vacuolization, as the tumor regressed, but no visible chromatin fragmentation. This is the first demonstration that 9NC is curative for human prostate carcinoma xenografts in the nude mouse model in the absence of detectable drug-induced toxicity during and after tumor regression. These findings indicate that 9NC may develop into a chemotherapeutic drug for the effective treatment of prostate cancer patients. Further, there was no apparent correlation of the steady-state level of the apoptosis-regulating proteins, Bcl-2, Bcl-XL, Bax and Ich-1, with tumorigenicity of the prostate cells xenografted in nude mice, aggressiveness of tumors grown in nude mice, and induction of apoptosis by 9NC. However, the TIAR protein was present at markedly high levels in all prostate carcinoma cell lines and this may correlate with their susceptibility to 9NC-induced apoptosis.

Isolation and characterization of an apoptosis-resistant variant of human leukemia HL-60 cells that has switched expression from Bcl-2 to Bcl-xL

Human promyelocytic leukemia HL-60 cells treated with 8-chloroadenosine-3',5'-cyclic monophosphate (8-Cl-cAMP) undergo growth arrest and subsequently die by apoptosis. We describe here the isolation of a variant of HL-60 cells, HCW-2, which was resistant to the cytotoxic effects of 8-Cl-cAMP, but still underwent growth arrest. Thus, HCW-2 cells appeared to be altered in their ability to undergo apoptosis. HCW-2 cells were also completely refractory to the apoptotic action of cycloheximide and staurosporine, two compounds which were very potent inducers of apoptosis in the parental HL-60 cells, suggesting that the resistance to apoptosis was not unique to 8-Cl-cAMP. Western blot analysis demonstrated that the parental HL-60 cells expressed both Bcl-2 and Bax, two factors known to be intimately involved in the control of apoptosis. Surprisingly, HCW-2 cells no longer expressed Bcl-2 protein and paradoxically contained Bax protein at a level that was approximately 50-fold higher than in HL-60 cells. However, Northern and Western analyses indicated that the apoptotic suppressor gene, bcl-xL, which is not expressed in the parental HL-60 cells, was expressed in HCW-2 cells. Thus, the Bcl-2-independent resistance of HCW-2 cells to apoptotic induction is discussed in terms of the expression of bcl-xL.

Evidence for a G2 checkpoint in p53-independent apoptosis induction by X-irradiation

The p53 tumor suppressor gene is thought to be required for the induction of programmed cell death (apoptosis) initiated by DNA damage. We show here, however, that the human promyelocytic leukemia cell line HL-60, which is known to be deficient in p53 because of large deletions in the p53 gene, can be induced to undergo apoptosis following X-irradiation. We demonstrate that the decision to undergo apoptosis in this cell line appears to be made at a G2 checkpoint. In addition, we characterize an HL-60 variant, HCW-2, which is radioresistant. HCW-2 cells display DNA damage induction and repair capabilities identical to those of the parental HL-60 cell line. Thus, the difference between the two cell lines appears to be that X-irradiation induces apoptosis in HL-60, but not in HCW-2, cells. Paradoxically, HCW-2 cells display high levels of expression of bax, which enhances apoptosis, and no longer express bcl-2, which blocks apoptosis. HCW-2 cells' resistance to apoptosis may be due to the acquisition of expression of bcl-XL, a bcl-2-related inhibitor of apoptosis. In summary, apoptosis can be induced in X-irradiated HL-60 cells by a p53-independent mechanism at a G2 checkpoint, despite the presence of endogenous bcl-2. The resistance shown by HCW-2 cells suggests that bcl-XL can block this process.

Development of human leukemia U-937 cell sublines resistant to doxorubicin: induction of differentiation and altered sensitivities to topoisomerase-directed drugs

Cell sublines resistant to doxorubicin (DOX) were developed from the human leukemia cell line, U-937/WT, exposed to stepwise DOX increases. In contrast to U-937/WT cells, the DOX-resistant U-937/RD cells have longer doubling time; are more differentiated along the monocytic lineage as determined by the presence of morphological features and mRNA coding for the monocyte colony-stimulating factor-1 receptor; synthesize the apoptosis-associated Bax protein; are less sensitive to apoptosis-inducing topoisomerase II-directed drugs, apparently because of increased synthesis of P-glycoprotein; and are practically non-tumorigenic when xenografted in nude mice. However, U-937/WT and U-937/RD cells exhibit similar sensitivity to the apoptosis-inducing drug 9-nitrocamptothecin. These findings suggest that several mechanisms are involved in the development of DOX-resistance in U-937 cells, and further, 9-nitrocamptothecin can overcome resistance to DOX. These findings may have clinical implications.

Sensitivity of camptothecin-resistant human leukemia cells and tumors to anticancer drugs with diverse mechanisms of action

Human leukemia U-937 cell clones resistant to 9-nitrocamptothecin (9NC) appear after exposure to increase 9NC-concentrations. Drug resistance is irreversible, regardless of whether the 9NC-resistant (U-937/CR150) cells grow in media with or without 9NC. U-937/CR150 cells are more sensitive than wild type U-937 (U-937/wt) cells to topoisomerase II-directed drugs, amsacrine, daunorubicin, and etoposide. The mitotic inhibitor, vincristine, induces hyperdiploidy in U-937/wt, but not in U-937/CR150 cells, whereas the antimetabolites, cytarabine and methotrexate, and the nitrosourea, carmustine, elicit similar responses in both U-937/wt and U-937/CR150 cells. U-937/CR150-generated tumors in nude mice are sensitive to etoposide. The clinical implications of increased sensitivity of 9NC-resistant tumors to some anticancer drugs are discussed.

Development of resistance to 9-nitro-camptothecin by human leukemia U-937 cells in vitro correlates with altered sensitivities to several anticancer drugs

We have recently reported that exposure of human leukemia U-937 cells to progressively increasing concentrations of 9-nitro-camptothecin (9NC) resulted in cell sublines exhibiting various levels of resistance to 9NC. Here, we report responses of wild-type (U-937/wt) and 9NC-resistant (U-937/CR) cells to various anticancer drugs used extensively in cancer chemotherapy. U-937/CR cells were more sensitive than U-937/wt cells to several commonly used drugs of diverse origin including the topoisomerase II-directed drugs amsacrine, etoposide and daunorubicin; the vinca alkaloid vincristine; and the antimetabolite methotrexate. No responses were induced by carmustine in either cell type, whereas similar responses were induced by cytarabine. The sensitivity to the drugs was investigated by monitoring cell proliferation, by determining cell cycle perturbations assessed by flow cytometry analysis of DNA content and by microscopy of stained cells. The results in this report indicate that development of 9NC resistance by the U-937 cells is accompanied by increased sensitivities to other anticancer drugs in vitro and very likely in vivo.

Sexual aggression and love styles: an exploratory study

The relationship between sexual aggression and theoretical love styles was studied. Based on self-reported sexual history, 63 college men were grouped as having either consensual sexual experience only (n = 33) or having verbally coercive sexual experience (n = 30). Analyses were conducted using six love style scales, likelihood to rape, likelihood to use sexual force, masculinity, and sociopathy to predict sexual coercive group membership. Logistic regression indicated that the Ludus love style, a manipulative, game-playing orientation towards intimate relationships, was the best predictor of sexual coercion among the six love styles. Additionally, logistic regression indicated that the Ludus love style was as effective in classifying men as coercive or noncoercive as other dispositions related to sexual aggression. These results suggest that the Ludus love style may serve as a unifying construct for dispositions related to sexual aggression. This study constitutes an initial attempt to link sexually coercive behaviors to a theoretical model of intimate relationships. Results are discussed in the context of a situational model of sexual coercion.

Altered atrial responses to drugs after acute exposure to nitrogen dioxide and/or ethanol

The responses of atria isolated from four groups of rats: (a) control (air/H2O) and test animals treated with (b) 5 PPM nitrogen dioxide NO2 for 72 hours, (NO2/H2O), (c) 10% ethanol (ET) in water for 13 days, (air/ET), or (d) combination of NO2 and ET (NO2/ET). Isolated atria were tested with norepinephrine and dose response curves determined. The chronotropic responses among groups were not different. However, there were significant differences when tested with pilocarpine and to lesser extent to increased calcium concentration in the bathing medium. Ethanol and/or NO2 attenuates parasympathetic activity possibly by altering receptor numbers or activity. The changes in calcium activity may result from altered calcium channel activity. This data indicates that acute exposure to NO2, ET and/or the interaction between these agents can alter cardiac activity.