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.

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'.

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.

Staphylococcal bacteremia in a "Germ-free" unit.

The rate of carriage and infections due to strains of Staphylococcus aureus were evaluated in adults with acute leukemia in isolators characterized by laminar air flow and barrier isolation. Patients were randomly given antimicrobial prophylaxis with oral nonabsorbed antibiotics and a nasal antibiotic ointment. In four years S aureus was isolated from the nostrils or other sites in 36 patients. Persistent isolation was noted in 24 patients. Suppression of gut flora was associated with a higher carriage rate of S aureus. Five episodes of bacteremia due to S aureus occurred at the nadir of leukopenia induced by chemotherapy. Death occurred within five days in the three patients whose peripheral white blood cell count did not rise. Patient isolation and suppression of gut flora helped reduce infections due to Pseudomonas sp and fungi, but S aureus emerged as a life-threatening pathogen.

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.

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.

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.

Cancer staging may have different meanings in academic and community hospitals.

We investigated differences in lung cancer care and outcome between academic and community settings for all lung cancer patients diagnosed during 1973-1976 in New Hampshire and Vermont. Trained abstracters reviewed hospital charts to record personal, diagnostic, and clinical information, and survival was determined for all patients through the end of 1979. Patients diagnosed in university hospital cancer centers underwent more staging procedures and tended to be assigned to a higher stage than similar patients diagnosed in community hospitals. When tumor stage was considered as a covariable in a survival analysis, these patients appeared to have a lower mortality rate both for non-small cell tumors (mortality rate ratio, 95% confidence interval = 0.81, 0.71-0.91) and for small cell tumors (0.71, 0.55-0.91). When functional status rather than tumor stage was used to adjust for disease severity, there was no apparent survival advantage for university patients with non-small cell cancer (0.96, 0.85-1.09) and the lower mortality for small cell cancers (0.76, 0.59-0.97) was attenuated, although still statistically significant. We conclude that inconsistently-collected data on clinical stage can complicate comparisons of prognosis between cancer patients from different types of hospitals and that measures of performance status may be more useful indicators of disease severity in population based studies.

Gas exchange and lactate anaerobic thresholds: inter- and intraevaluator agreement.

Twenty-four coded graph sets of gas exchange variables and blood lactate concentration (LA) plotted against time at 15-s intervals were analyzed by nine evaluators who determined the gas exchange (ATGE) and LA (ATLA) anaerobic thresholds. In addition, ATGE and ATLA were determined by a linear regression computer program. Agreement between ATGE and ATLA was poor; the median intraclass correlation coefficient (ri) was 0.53. Among evaluators, ATLA agreement (median ri = 0.81) was better than ATGE agreement (median ri = 0.70). In general, the ability of any evaluator to choose similar values from duplicate plots for either ATGE (median ri = 0.97) or ATLA (median ri = 0.995) was good. There was better agreement between the mean ATLA of the evaluators and the computer ATLA (ComLA) (ri = 0.88) than between the mean ATGE of the evaluators and the computer ATGE (ComVE), (ri = 0.58). Agreement between ComVE and ComLA was poor (ri = 0.29). These results suggest that ATGE does not accurately predict ATLA and that different evaluators choose different thresholds from the same data. Further assessment of the validity and precision of ATGE based on breath-by-breath and minute-by-minute data is needed.

Prediction and management of pain in patients with advanced cancer.

In a prospective controlled study, patients with incurable cancer and an estimated prognosis of three months to one year were allocated to two patient groups for evaluation of supportive interventions. One group, called "intensive," received home visits by a nurse practitioner acting as an extension of a multidisciplinary team; the other, termed "nonintensive," did not receive such visits. Both patient groups were periodically evaluated in their homes by an observer and by self-ratings, to measure changes in quality of life as their disease progressed. Several methodologic problems were identified, which have implications for future research. Pain problems later in the course of cancer seem to be predictable in those patients with higher scores on the Cornell Medical Index M-R scales (greater emotional disturbance) and on the Rotter Locus of Control (I-E) scale (expectation of more external control of self). The study also found that the home visiting nurse practitioners, specially trained in pain treatment, improved pain control in the "intensive" group of patients over the last 90 days of life, when pain was an increasingly major problem. Such nurses can significantly improve the quality of life for patients dying outside of institutions.

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.

Effect of a mandibular orthopedic repositioning appliance on muscular strength.

Three tests of large-muscle group strength were performed on 14 football players from the University of Louisville. Strength tests were performed with no mouthpiece, with a placebo mouthpiece, and with a MORA mouthpiece. A repeated measures ANOVA showed no significant differences between any of the tests, suggesting that the MORA has no effect on muscular strength.

Maximum acceptable lifting loads during seated and standing work positions.

The psychophysical method was used to determine the maximal acceptable load that eight males (age 22-30 years) would lift in each of four different positions: (1) seated, two-handed, symmetrical lift from a table, to a position 38 cm forward of the edge, (2) a seated lift from a position at the subject's side, on to a table in front of the subject involving a 90 degree twist of the torso, (3) standing, two-handed, symmetrical lift from the table, to a position 38 cm forward of the edge, and (4) standing, vertical lift from 86 above the floor. Subsequent to a training period, subjects lifted a tray with slotted handles at the rate of 1 or 4 lifts/min. Each subject chose the weight of the tray which was acceptable to him by adding or removing flat pieces of lead over a 45 min period. The weight of the tray, heart rate, and the perceived exertion were measured at 15, 30 and 45 min. Oxygen consumption was measured during the last 5 min of the 45 min experiment. Statistical analysis revealed a significant frequency and position effect. An increase in frequency from 1 to 4 lifts/min resulted in a decrease of 1.6 to 2.1 kg in the maximum acceptable weight for the various tasks. On average, the maximum acceptable weight of lift for standing positions was 16% greater than for sitting positions. Oxygen consumption and heart rate were significantly higher for 4 lifts/min than for 1 lift/min; however, the rating of perceived exertion did not differ for any factor.

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.