Multiscalar cellular automaton simulates in-vivo tumour-stroma patterns calibrated from in-vitro assay data.

BACKGROUND: The tumour stroma -or tumour microenvironment- is an important constituent of solid cancers and it is thought to be one of the main obstacles to quantitative translation of drug activity between the preclinical and clinical phases of drug development. The tumour-stroma relationship has been described as being both pro- and antitumour in multiple studies. However, the causality of this complex biological relationship between the tumour and stroma has not yet been explored in a quantitative manner in complex tumour morphologies. METHODS: To understand how these stromal and microenvironmental factors contribute to tumour physiology and how oxygen distributes within them, we have developed a lattice-based multiscalar cellular automaton model. This model uses principles of cytokine and oxygen diffusion as well as cell motility and plasticity to describe tumour-stroma landscapes. Furthermore, to calibrate the model, we propose an innovative modelling platform to extract model parameters from multiple in-vitro assays. This platform provides a novel way to extract meta-data that can be used to complement in-vivo studies and can be further applied in other contexts. RESULTS: Here we show the necessity of the tumour-stroma opposing relationship for the model simulations to successfully describe the in-vivo stromal patterns of the human lung cancer cell lines Calu3 and Calu6, as models of clinical and preclinical tumour-stromal topologies. This is especially relevant to drugs that target the tumour microenvironment, such as antiangiogenics, compounds targeting the hedgehog pathway or immune checkpoint inhibitors, and is potentially a key platform to understand the mechanistic drivers for these drugs. CONCLUSION: The tumour-stroma automaton model presented here enables the interpretation of complex in-vitro data and uses it to parametrise a model for in-vivo tumour-stromal relationships.

Non-invasive 3D time-of-flight imaging technique for tumour volume assessment in subcutaneous models.

Subcutaneous tumour xenograft volumes are generally measured using callipers. This method is susceptible to inter- and intra-observer variability and systematic inaccuracies. Non-invasive 3D measurement using ultrasound and magnetic resonance imaging (MRI) have been considered, but require immobilization of the animal. An infrared-based 3D time-of-flight (3DToF) camera was used to acquire a depth map of tumour-bearing mice. A semi-automatic algorithm based on parametric surfaces was applied to estimate tumour volume. Four clay mouse models and 18 tumour-bearing mice were assessed using callipers (applying both prolate spheroid and ellipsoid models) and 3DToF methods, and validated using tumour weight. Inter-experimentalist variability could be up to 25% in the calliper method. Experimental results demonstrated good consistency and relatively low error rates for the 3DToF method, in contrast to biased overestimation using callipers. Accuracy is currently limited by camera performance; however, we anticipate the next generation 3DToF cameras will be able to support the development of a practical system. Here, we describe an initial proof of concept for a non-invasive, non-immobilized, morphology-independent, economical and potentially more precise tumour volume assessment technique. This affordable technique should maximize the datapoints per animal, by reducing the numbers required in experiments and reduce their distress.

A new general glucose homeostatic model using a proportional-integral-derivative controller.

The glucose-insulin system is a challenging process to model due to the feedback mechanisms present, hence the implementation of a model-based approach to the system is an on-going and challenging research area. A new approach is proposed here which provides an effective way of characterising glycaemic regulation. The resulting model is built on the premise that there are three phases of insulin secretion, similar to those seen in a proportional-integral-derivative (PID) type controller used in engineering control problems. The model relates these three phases to a biological understanding of the system, as well as the logical premise that the homeostatic mechanisms will maintain very tight control of the system. It includes states for insulin, glucose, insulin action and a state to simulate an integral function of glucose. Structural identifiability analysis was performed on the model to determine whether a unique set of parameter values could be identified from the available observations, which should permit meaningful conclusions to be drawn from parameter estimation. Although two parameters--glucose production rate and the proportional control coefficient--were found to be unidentifiable, the former is not a concern as this is known to be impossible to measure without a tracer experiment, and the latter can be easily estimated from other means. Subsequent parameter estimation using Intravenous Glucose Tolerance Test (IVGTT) and hyperglycaemic clamp data was performed and subsequent model simulations have shown good agreement with respect to these real data.

Oral and IV dosing: a method to determine the compartment of drug elimination for two-compartment models.

It has been shown previously that it is impossible to measure the volume of distribution at steady state conclusively for a multicompartment system from an iv bolus dose only. The problem lies in deciding from which compartment elimination of the drug occurs in the compartmental model. In this paper a new modelling strategy is examined whereby the compartment of elimination may be identified uniquely for the case of two-compartment models. The two models examined predict different profiles in the absorption phase of an oral profile. An in vivo data set is provided that favours a peripheral elimination explanation of its observed pharmacokinetics, based on the 'goodness of fit'.

Data reduction in headspace analysis of blood and urine samples for robust bacterial identification.

This paper demonstrates the application of chemical headspace analysis to the problem of classifying the presence of bacteria in biomedical samples by using computational tools. Blood and urine samples of disparate forms were analysed using a Cyrano Sciences C320 electronic nose together with an Agilent 4440 Chemosensor. The high dimensional data sets resulting from these devices present computational problems for parameter estimation of discriminant models. A variety of data reduction and pattern recognition techniques were employed in an attempt to optimise the classification process. A 100% successful classification rate for the blood data from the Agilent 4440 was achieved by combining a Sammon mapping with a radial basis function neural network. In comparison a successful classification rate of 80% was achieved for the urine data from the C320 which were analysed using a novel nonlinear time series model.

Effect of age and comorbidity in postmenopausal breast cancer patients aged 55 years and older.

CONTEXT: Postmenopausal women aged 55 years and older have 66% of incident breast tumors and experience 77% of breast cancer mortality, but other age-related health problems may affect tumor prognosis and treatment decisions. OBJECTIVE: To document the comorbidity burden of postmenopausal breast cancer patients and evaluate its relationship with age on disease stage, treatment, and early mortality. DESIGN AND SETTING: Data were collected on breast cancer patients' comorbidities by retrospective hospital medical records review and merged with information on patients' tumor characteristics collected from 6 regional National Cancer Institute Surveillance, Epidemiology, and End Results cancer registries. Patients were followed up until death or for 30 months from breast cancer diagnosis. PARTICIPANTS: Population-based random sample of 1800 postmenopausal breast cancer patients diagnosed in 1992 stratified by 3 age groups: 55 to 64 years, 65 to 74 years, and 75 years and older. MAIN OUTCOME MEASURES: Extent of disease, therapy received, comorbidity, cause of death, and survival. RESULTS: Seventy-three percent (1312 of 1800) of the sample was diagnosed with stage I and II breast cancer, 10% (n = 188) with stage III and IV breast cancer, and 17% (n = 300) did not have a stage assignment. Of the 1017 patients with stage I and stage II node-negative breast cancer, 95% received therapy in agreement with the National Institutes of Health consensus statement recommendation for early-stage breast cancer. Patients in older age groups were less likely to receive therapy consistent with the consensus statement (P<.001), and women aged 70 years and older were significantly less likely to receive axillary lymph node dissection as determined by logistic regression analysis (P<.01). Diabetes, renal failure, stroke, liver disease, a previous malignant tumor, and smoking were significant in predicting early mortality in a statistical model that included age and disease stage. Breast cancer was the underlying cause of death for 135 decedents (51.3%). Heart disease (n = 45, 17.1%) and previous cancers (n = 22, 8.4%) were the next major underlying causes. In the 30-month follow-up period, 263 patients (15%) died. CONCLUSION: Patient care decisions occur in the context of breast cancer and other age-related conditions. Comorbidity in older patients may limit the ability to obtain prognostic information (ie, axillary lymph node dissection), tends to minimize treatment options (eg, breast-conserving therapy), and increases the risk of death from causes other than breast cancer.

Comorbidity considerations in geriatric oncology research.

Although it is generally acknowledged that comorbidity has a significant impact on treatment selection and outcomes for elderly patients with cancer, an understanding of how comorbid conditions should influence clinical decisions is quite incomplete. This issue remains an important and challenging area of geriatric oncology research. Measures of comorbidity require recognition, documentation, and accurate data extraction. Extensive prospective evaluations and medical chart reviews have the greatest reliability but are costly. Administrative data are convenient and applicable to large populations, but suffer from relatively poor reliability and therefore should be used with caution. Perhaps in the future more refined nosology and better information systems will improve our understanding and ability to use administrative data sets to study comorbidity in the elderly--the eventual goal of such investigation being evidence-based criteria for care of elderly cancer patients.

Selective small molecule inhibitors of glycogen synthase kinase-3 modulate glycogen metabolism and gene transcription.

BACKGROUND: Glycogen synthase kinase-3 (GSK-3) is a serine/threonine protein kinase, the activity of which is inhibited by a variety of extracellular stimuli including insulin, growth factors, cell specification factors and cell adhesion. Consequently, inhibition of GSK-3 activity has been proposed to play a role in the regulation of numerous signalling pathways that elicit pleiotropic cellular responses. This report describes the identification and characterisation of potent and selective small molecule inhibitors of GSK-3. RESULTS: SB-216763 and SB-415286 are structurally distinct maleimides that inhibit GSK-3alpha in vitro, with K(i)s of 9 nM and 31 nM respectively, in an ATP competitive manner. These compounds inhibited GSK-3beta with similar potency. However, neither compound significantly inhibited any member of a panel of 24 other protein kinases. Furthermore, treatment of cells with either compound stimulated responses characteristic of extracellular stimuli that are known to inhibit GSK-3 activity. Thus, SB-216763 and SB-415286 stimulated glycogen synthesis in human liver cells and induced expression of a beta-catenin-LEF/TCF regulated reporter gene in HEK293 cells. In both cases, compound treatment was demonstrated to inhibit cellular GSK-3 activity as assessed by activation of glycogen synthase, which is a direct target of this kinase. CONCLUSIONS: SB-216763 and SB-415286 are novel, potent and selective cell permeable inhibitors of GSK-3. Therefore, these compounds represent valuable pharmacological tools with which the role of GSK-3 in cellular signalling can be further elucidated. Furthermore, development of similar compounds may be of use therapeutically in disease states associated with elevated GSK-3 activity such as non-insulin dependent diabetes mellitus and neurodegenerative disease.

The role of ATP citrate-lyase in the metabolic regulation of plasma lipids. Hypolipidaemic effects of SB-204990, a lactone prodrug of the potent ATP citrate-lyase inhibitor SB-201076.

ATP citrate (pro-S)-lyase (EC 4.1.3.8), a cytosolic enzyme that generates acetyl-CoA for cholesterol and fatty acid synthesis de novo, is a potential target for hypolipidaemic intervention. Here we describe the biological effects of the inhibition of ATP citrate-lyase on lipid metabolism in Hep G2 cells, and plasma lipids in rats and dogs, by using SB-204990, the cell-penetrant gamma-lactone prodrug of the potent ATP citrate-lyase inhibitor SB-201076 (Ki=1 microM). Consistent with an important role of ATP citrate-lyase in the supply of acetyl-CoA units for lipid synthesis de novo, SB-204990 inhibited cholesterol synthesis and fatty acid synthesis in Hep G2 cells (dose-related inhibition of up to 91% and 82% respectively) and rats (76% and 39% respectively). SB-204990, when administered orally to rats, was absorbed into the systemic circulation; pharmacologically relevant concentrations of SB-201076 were recovered in the liver. When administered in the diet (0.05-0. 25%, w/w) for 1 week, SB-204990 caused a dose-related decrease in plasma cholesterol (by up to 46%) and triglyceride levels (by up to 80%) in rats. This hypolipidaemic effect could be explained, at least in part, by a decrease (up to 48%) in hepatic very-low-density lipoprotein (VLDL) production as measured by the accumulation of VLDL in plasma after injection of Triton WR-1339. SB-204990 (25 mg/kg per day) also decreased plasma cholesterol levels (by up to 23%) and triglyceride levels (by up to 38%) in the dog, preferentially decreasing low-density lipoprotein compared with high-density lipoprotein cholesterol levels. Overall these results are consistent with the concept that ATP citrate-lyase is an important enzyme in controlling substrate supply for lipid synthesis de novo and a potential enzyme target for hypolipidaemic intervention.

Apolipoprotein E*3-Leiden transgenic mice as a test model for hypolipidaemic drugs.

Apolipoprotein (APO) E*3-Leiden mice with impaired chylomicron and VLDL (very low density lipoprotein) remnant metabolism display hyperlipidaemia and atherosclerosis. In the present study, these mice were used for testing the hypolipidaemic effect of two marketed agents, lovastatin (CAS 75330-75-5) and gemfibrozil (CAS 25812-30-0) as well as a novel compound, SB 204990 (the 5-ring lactone of +/-(3R*,5S*) 3-carboxy-11-(2,4-dichlorophenyl)-3,5-dihydroxyundecanoic acid, CAS 154566-12-8), a potent inhibitor of cholesterol and fatty acid synthesis at the level of ATP-citrate lyase. APOE*3-Leiden mice were fed a saturated fat and cholesterol-rich diet supplemented with either 0.05 or 0.1% w/w of lovastatin, 0.1 or 0.2% w/w of gemfibrozil or 0.1 or 0.2% w/w of SB 204990. Lovastatin showed a dose-related decrease in plasma cholesterol levels (up to -20%) due to a lowering of LDL and HDL (low density resp. high density lipoprotein)-cholesterol (-20 and -18%, respectively), while plasma triglyceride levels were unaffected. Gemfibrozil had no effect on plasma total cholesterol levels but gave significant dose-dependent decreases in plasma (VLDL) triglyceride levels (up to -53%). SB 204990 resulted in a dose-dependent reduction of plasma cholesterol (up to -29%) by lowering VLDL, LDL and HDL-cholesterol (-50, -20 and -20%, respectively). In addition, a strong dose dependent reduction of plasma (VLDL) triglycerides up to -43% was observed with this compound. Although the effects of gemfibrozil and SB 204990 were not simply explained by changes in a single determinant of VLDL metabolism--no effects of these drugs were seen on post-heparin plasma lipoprotein lipase activity, in vivo rate of VLDL synthesis or hepatic apoC-III mRNA levels--APOE*3-Leiden mice were found to give robust hypolipidaemic responses to these test compounds. The responsiveness to hypolipidaemic therapy combined with a clear relationship between aortic lesion size and plasma cholesterol exposure, as demonstrated previously, makes this mouse an attractive model for the testing of anti-atherosclerotic properties of hypolipidaemic drugs.

Comorbidity and age as predictors of risk for early mortality of male and female colon carcinoma patients: a population-based study.

BACKGROUND: Colon carcinoma primarily affects persons 65 years and older. Seventy-five percent of the incident tumors affect persons in this age group. Because of their advanced age, older patients already may be coping with other concomitant major physical illnesses. This article documents preexisting diseases in older colon carcinoma patients at diagnosis and evaluates the effects of their comorbidity burden on early mortality. METHODS: Prevalence of comorbid conditions was assessed by a retrospective medical records review of an age-stratified random sample of male and female patients aged 55-64 years, 65-74 years, and 75+ years (males, n=799; females, n=811). Data were collected on comorbidity by the National Institute on Aging (NIA) and National Cancer Institute (NCI) and merged with NCI Surveillance, Epidemiology, and End Results (SEER) tumor registry data. RESULTS: Hypertension, high impact heart conditions, gastrointestinal problems, arthritis, and chronic obstructive pulmonary disease emerged as the most prominent comorbid conditions in the NIA/NCI SEER Study sample. The prevalence of comorbidity in the number and type of conditions was similar for both men and women (e.g., 40% of each gender had > or = 5 comorbidities). Within 2 years of diagnosis, 28% (n=454) of the patients had died. The number of comorbid conditions was significant in predicting early mortality in a model including age, gender, and disease stage (P=0.0007). Certain comorbidities, classified as "current problem," added significantly to a basic model (e.g., heart problems, alcohol abuse, liver disease, and deep vein thrombosis). CONCLUSIONS: Although disease stage at time of diagnosis of colon carcinoma is a crucial determinant of patient outcome, comorbidity increases the complexity of cancer management and affects survival duration. Cancer control and treatment research questions should address comorbidity issues pertinent to the age group primarily afflicted with colon carcinoma (i.e., the elderly).

Effect of simultaneous exercise and noise exposure (music) on hearing.

Hearing thresholds were measured in 12 subjects prior to and following their participation in three experimental conditions: (a) riding a cycle ergometer for 20 minutes; (b) listening to a selection of music at an equivalent intensity of 96 dB(A) SPL for 20 minutes; and (c) listening to the music while riding the cycle ergometer for 20 minutes. Analysis of the results shows a measurable and statistically greater noise-induced temporary threshold shift (NITTS) for the music plus exercise condition that for either of the other two conditions. The greatest differences were seen in the 3-6 kHz frequency range. These results suggest an increased susceptibility to NITTS and, by extension, to increased potential for permanent hearing loss when noise exposure is coupled with exercise. The results have implications related to contemporary lifestyle issues such as aerobics and the utilization of personal music systems during physical exertion.

Dietary ethanol stimulates the activity of phosphatidylcholine-specific phospholipase D and the formation of phosphatidylethanol in Drosophila melanogaster larvae.

When administered in the diet to third instar Drosophila melanogaster larvae, short chain primary alcohols reduce phosphatidylcholine (PC) levels. The ethanol-induced reductions in larval PC may be in part due to an increase in the activity of PC-specific phospholipase D (PC-specific PLD, EC 3.1.4.4). PC-specific PLD not only hydrolyzes PC, but it also apparently catalyzes the formation of phosphatidylethanol. PC-specific PLD activity was also stimulated by 200 mM ethanol, methanol, isopropanol, n-butanol, and n-propanol. In vitro studies indicated that Drosophila PC-specific PLD activities were enhanced by submicromolar concentrations of Ca2+ and by GTP-gamma S. In vivo studies utilizing [14C]lyso-palmitoyl phosphatidylcholine indicated that dietary ethanol promoted the flux of label into triacylglycerol, 1,2 diacylglycerol, and fatty acid ethyl esters, while the label in PC decreased.

The INO1 promoter of Saccharomyces cerevisiae includes an upstream repressor sequence (URS1) common to a diverse set of yeast genes.

The INO1 promoter of Saccharomyces cerevisiae includes a copy of an upstream repression sequence (URS1; 5'AGCCGCCGA 3') observed in the promoters of several unrelated yeast genes. Expression of INO1-lacZ and CYC1-lacI'Z, activated by the INO1 UASINO, is significantly decreased by the INO1 URS1.

Dietary ethanol reduces phosphatidylcholine levels and inhibits the uptake of dietary choline in Drosophila melanogaster larvae.

1. Low to moderate concentrations of dietary ethanol (200 mM to 600 mM) significantly increased the level of phosphatidylethanolamine (PE), while phosphatidylcholine (PC) levels decreased in third instar larvae. This was seen in both ethanol tolerant and intolerant strains of Drosophila melanogaster, indicating that the reduction of PC is not associated with a high level of ethanol tolerance. 2. The phospholipid changes were not ethanol-specific. Larvae fed ethanol, n-butanol, isopropanol, methanol, and n-propanol exhibited similar changes. 3. At 200 mM concentrations, dietary ethanol acted as a competitive inhibitor for the larval uptake of dietary choline. At higher concentrations, dietary ethanol acted as a noncompetitive inhibitor. This ethanol-induced inhibition of dietary choline uptake can only partially explain the ethanol-induced reductions in larval PC.

Discriminability of load heaviness: implications for the psychophysical approach to manual lifting.

The main objective of this study was to investigate human ability to discriminate between different levels of load heaviness in manual lifting. Twelve male college students participated in the laboratory experiment. Twenty-eight sequences of five boxes that weighed from 5 to 64 lbs (2.27-29.1 kg) were used. The subjects were asked to arrange boxes in each sequence in order of the perceived (increasing or decreasing) heaviness, i.e., from lightest to the heaviest box, or from heaviest to the lightest box. The subjects were also asked to assign linguistic descriptors of perceived load heaviness to each box in the sequence, and to indicate the confidence levels regarding correctness of the assigned box order and assignment of linguistic values. The independent variables included magnitude of weight and load differential between the successive weights in a sequence. The number of sequential ordering errors, assignment of linguistic variables, and estimated confidence levels were highly dependent on the load differential and weight range. It was concluded that in order to assure reliable results of the psychophysical approach to determining the values of maximum acceptable weight of lift, the adjustment process for male subjects should require using small weights of at least 4 lbs (1.8 kg) to be added or removed from the lifted box. The results of this study also suggest that the error rate in load discriminability can be controlled below the 10% level, if the relative difference in weight between successive boxes lifted is at least 12%. Given the above findings, it is suggested that usefulness of some of the recommendations for setting safe limits for manual lifting tasks, which were reached based on the psychophysical approach and broadly reported in the past, may need to be carefully re-examined. Finally, this study showed that the Weber fraction for load heaviness over the range of lifted weights from 8.6 to 29.1 kg is between 0.03 and 0.04.

An electromyographic analysis of seated and standing lifting tasks.

The objective of this project was to compare the muscular effort exerted during manual lifting tasks performed in standing versus seated posture. Six male undergraduate and graduate students performed 12 different static and dynamic lifts in both sitting and standing positions. During each effort electromyographic (EMG) data were collected on four muscles groups (low back, upper back, shoulder, and abdominals). Four contractions were designed to elicit maximum muscular effort in the four groups being monitored. The remaining data were then expressed as a percentage of maximum EMG. Each subject performed the following: maximum static lift when sitting; maximum static lift when standing; sitting, static lift with 15.9 kg; standing, static lift with 15.9 kg; dynamic sit-forward lift with 15.9 kg, dynamic stand-forward lift with 15.9 kg, dynamic sit-twist with 15.9 kg, dynamic stand-vertical lift with 15.9 kg. Each of the lifts was performed with a wooden tray with slotted handles. Root mean square (RMS) values of the EMG data were calculated for three second periods. EMG activity in the low back, upper back, and shoulder was greater during sitting lifting than during standing lifting. The sit-twist lift resulted in the highest EMG in the abdominal muscles. Dynamic lifts resulted in more muscle activity than did static lifts. From these data it was concluded that sitting-lifting results in greater stress in the low back, upper back, and shoulders than does lifting while standing.