Manchester Intermittent Diet in Gestational Diabetes Acceptability Study (MIDDAS-GDM): a two-arm randomised feasibility protocol trial of an intermittent low-energy diet (ILED) in women with gestational diabetes and obesity in Greater Manchester

INTRODUCTION

The prevalence of gestational diabetes mellitus (GDM) is rising in the UK and is associated with maternal and neonatal complications. National Institute for Health and Care Excellence guidance advises first-line management with healthy eating and physical activity which is only moderately effective for achieving glycaemic targets. Approximately 30% of women require medication with metformin and/or insulin. There is currently no strong evidence base for any particular dietary regimen to improve outcomes in GDM. Intermittent low-energy diets (ILEDs) are associated with improved glycaemic control and reduced insulin resistance in type 2 diabetes and could be a viable option in the management of GDM. This study aims to test the safety, feasibility and acceptability of an ILED intervention among women with GDM compared with best National Health Service (NHS) care.

METHOD AND ANALYSIS

We aim to recruit 48 women with GDM diagnosed between 24 and 30 weeks gestation from antenatal clinics at Wythenshawe and St Mary's hospitals, Manchester Foundation Trust, over 13 months starting in November 2022. Participants will be randomised (1:1) to ILED (2 low-energy diet days/week of 1000 kcal and 5 days/week of the best NHS care healthy diet and physical activity advice) or best NHS care 7 days/week until delivery of their baby. Primary outcomes include uptake and retention of participants to the trial and adherence to both dietary interventions. Safety outcomes will include birth weight, gestational age at delivery, neonatal hypoglycaemic episodes requiring intervention, neonatal hyperbilirubinaemia, admission to special care baby unit or neonatal intensive care unit, stillbirths, the percentage of women with hypoglycaemic episodes requiring third-party assistance, and significant maternal ketonaemia (defined as ≥1.0 mmol/L). Secondary outcomes will assess the fidelity of delivery of the interventions, and qualitative analysis of participant and healthcare professionals' experiences of the diet. Exploratory outcomes include the number of women requiring metformin and/or insulin.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the Cambridge East Research Ethics Committee (22/EE/0119). Findings will be disseminated via publication in peer-reviewed journals, conference presentations and shared with diabetes charitable bodies and organisations in the UK, such as Diabetes UK and the Association of British Clinical Diabetologists.

TRIAL REGISTRATION NUMBER

NCT05344066.

Parameter-Free State Estimation Based on Kalman Filter with Attention Learning for GPS Tracking in Autonomous Driving System

GPS-based maneuvering target localization and tracking is a crucial aspect of autonomous driving and is widely used in navigation, transportation, autonomous vehicles, and other fields.The classical tracking approach employs a Kalman filter with precise system parameters to estimate the state. However, it is difficult to model their uncertainty because of the complex motion of maneuvering targets and the unknown sensor characteristics. Furthermore, GPS data often involve unknown color noise, making it challenging to obtain accurate system parameters, which can degrade the performance of the classical methods. To address these issues, we present a state estimation method based on the Kalman filter that does not require predefined parameters but instead uses attention learning. We use a transformer encoder with a long short-term memory (LSTM) network to extract dynamic characteristics, and estimate the system model parameters online using the expectation maximization (EM) algorithm, based on the output of the attention learning module. Finally, the Kalman filter computes the dynamic state estimates using the parameters of the learned system, dynamics, and measurement characteristics. Based on GPS simulation data and the Geolife Beijing vehicle GPS trajectory dataset, the experimental results demonstrated that our method outperformed classical and pure model-free network estimation approaches in estimation accuracy, providing an effective solution for practical maneuvering-target tracking applications.

Location estimation based on feature mode matching with deep network models

Introduction

Global navigation satellite system (GNSS) signals can be lost in viaducts, urban canyons, and tunnel environments. It has been a significant challenge to achieve the accurate location of pedestrians during Global Positioning System (GPS) signal outages. This paper proposes a location estimation only with inertial measurements.

Methods

A method is designed based on deep network models with feature mode matching. First, a framework is designed to extract the features of inertial measurements and match them with deep networks. Second, feature extraction and classification methods are investigated to achieve mode partitioning and to lay the foundation for checking different deep networks. Third, typical deep network models are analyzed to match various features. The selected models can be trained for different modes of inertial measurements to obtain localization information. The experiments are performed with the inertial mileage dataset from Oxford University.

Results and discussion

The results demonstrate that the appropriate networks based on different feature modes have more accurate position estimation, which can improve the localization accuracy of pedestrians in GPS signal outages.

Deep Spatio-Temporal Graph Network with Self-Optimization for Air Quality Prediction

The environment and development are major issues of general concern. After much suffering from the harm of environmental pollution, human beings began to pay attention to environmental protection and started to carry out pollutant prediction research. A large number of air pollutant predictions have tried to predict pollutants by revealing their evolution patterns, emphasizing the fitting analysis of time series but ignoring the spatial transmission effect of adjacent areas, leading to low prediction accuracy. To solve this problem, we propose a time series prediction network with the self-optimization ability of a spatio-temporal graph neural network (BGGRU) to mine the changing pattern of the time series and the spatial propagation effect. The proposed network includes spatial and temporal modules. The spatial module uses a graph sampling and aggregation network (GraphSAGE) in order to extract the spatial information of the data. The temporal module uses a Bayesian graph gated recurrent unit (BGraphGRU), which applies a graph network to the gated recurrent unit (GRU) so as to fit the data's temporal information. In addition, this study used Bayesian optimization to solve the problem of the model's inaccuracy caused by inappropriate hyperparameters of the model. The high accuracy of the proposed method was verified by the actual PM2.5 data of Beijing, China, which provided an effective method for predicting the PM2.5 concentration.

Regional variation in longitudinal trajectories of primary care opioids prescribing across Health Boards in Scotland: a population-based study

BACKGROUND

This study aims to describe the longitudinal trajectory of opioid prescribing at the practice level and assess associated factors, including Health Boards and socioeconomic status.

RESEARCH DESIGN AND METHODS

This drug utilization research used practice-level dispensing data from 2016 to 2018. Practice-level prescription opioids dispensed were quantified by the defined daily doses (DDDs) per 1000 registrants. Group-based trajectory models were used to identify groups of practices with similar trajectories based on the difference in monthly opioid utilization. Characteristics of registrants were associated with the trajectory by a conditional logistic regression and the prescription opioids dispensed by a random-effect regression model.

RESULTS

Of the 798 practices, 29.5% increased opioid prescription by an additional 100 DDDs/1000 registrants/month during 2017 and 2018. Practice in southwest Scotland tended to be categorized into the group with increasing opioid utilization. Deprived socioeconomic status was associated with increasing opioid utilization (odds ratio: 2.2; 95% confidence interval: 1.5, 3.2) or higher annual opioid utilization (coefficient: 358.2; 95% confidence interval: 327.6, 388.8).

CONCLUSIONS

Increasing opioid utilization over time was related to deprived socioeconomic status associated with chronic pain conditions and inequality in pain services. Further strategies to balance inequality are needed, which needs further investigation.

Investigating the prescribing trajectory and geographical drug utilisation patterns of gabapentinoids in primary care in England: An ecological study

AIMS

This study aimed to investigate the prescribing trajectory, geographical variation and population factors, including socioeconomic status (SES), related to prescribing gabapentinoids in primary care in England.

METHODS

This ecological study applied practice-level dispensing data and statistics from the UK National Health Service Digital and Office for National Statistics from 2013 to 2019. The prescribing of gabapentinoids (in defined daily doses [DDDs]/1000 people) was measured annually and quarterly. General practices were categorised according to the quarterly prescribing in a group-based trajectory model. The one-year prescribing in 2018/19 was associated with practice-level covariates in a mixed-effects multilevel regression, adjusted for the cluster-effects of Clinical Commissioning Groups (CCGs) and mapped geographically.

RESULTS

The annual national prescription rate increased by 70% from 2800 to 4773 DDDs/1000 people in the time period 2013/14 to 2018/19. General practices were stratified into six trajectory groups. Practices with the highest level and the greatest increase in prescribing (n = 789; 9.8%) are mainly located in the north of England and along the east and south coastline. Socioeconomic status, demographic characteristics and relevant disease conditions were significantly associated with the prescribing. For every decrease in the Index of Multiple Deprivation decile (becoming less affluent), prescribing of gabapentinoids increased significantly by 203 (95% CI: 183-222) DDDs/1000 registrants.

CONCLUSIONS

Gabapentinoid prescribing trajectories varied across geographical regions and are associated with socioeconomic status, CCG locality (geography) and other population characteristics. These factors should be considered in future studies investigating the determinants of gabapentinoid prescribing and the risk of harms associated with gabapentinoids.

Imaging modalities to inform the detection and diagnosis of early caries

BACKGROUND

The detection and diagnosis of caries at the earliest opportunity is fundamental to the preservation of tooth tissue and maintenance of oral health. Radiographs have traditionally been used to supplement the conventional visual-tactile clinical examination. Accurate, timely detection and diagnosis of early signs of disease could afford patients the opportunity of less invasive treatment with less destruction of tooth tissue, reduce the need for treatment with aerosol-generating procedures, and potentially result in a reduced cost of care to the patient and to healthcare services.

OBJECTIVES

To determine the diagnostic accuracy of different dental imaging methods to inform the detection and diagnosis of non-cavitated enamel only coronal dental caries.

SEARCH METHODS

Cochrane Oral Health's Information Specialist undertook a search of the following databases: MEDLINE Ovid (1946 to 31 December 2018); Embase Ovid (1980 to 31 December 2018); US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov, to 31 December 2018); and the World Health Organization International Clinical Trials Registry Platform (to 31 December 2018). We studied reference lists as well as published systematic review articles.

SELECTION CRITERIA

We included diagnostic accuracy study designs that compared a dental imaging method with a reference standard (histology, excavation, enhanced visual examination), studies that evaluated the diagnostic accuracy of single index tests, and studies that directly compared two or more index tests. Studies reporting at both the patient or tooth surface level were included. In vitro and in vivo studies were eligible for inclusion. Studies that explicitly recruited participants with more advanced lesions that were obviously into dentine or frankly cavitated were excluded. We also excluded studies that artificially created carious lesions and those that used an index test during the excavation of dental caries to ascertain the optimum depth of excavation.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently and in duplicate using a standardised data extraction form and quality assessment based on QUADAS-2 specific to the clinical context. Estimates of diagnostic accuracy were determined using the bivariate hierarchical method to produce summary points of sensitivity and specificity with 95% confidence regions. Comparative accuracy of different radiograph methods was conducted based on indirect and direct comparisons between methods. Potential sources of heterogeneity were pre-specified and explored visually and more formally through meta-regression.

MAIN RESULTS

We included 104 datasets from 77 studies reporting a total of 15,518 tooth sites or surfaces. The most frequently reported imaging methods were analogue radiographs (55 datasets from 51 studies) and digital radiographs (42 datasets from 40 studies) followed by cone beam computed tomography (CBCT) (7 datasets from 7 studies). Only 17 studies were of an in vivo study design, carried out in a clinical setting. No studies were considered to be at low risk of bias across all four domains but 16 studies were judged to have low concern for applicability across all domains. The patient selection domain had the largest number of studies judged to be at high risk of bias (43 studies); the index test, reference standard, and flow and timing domains were judged to be at high risk of bias in 30, 12, and 7 studies respectively. Studies were synthesised using a hierarchical bivariate method for meta-analysis. There was substantial variability in the results of the individual studies, with sensitivities that ranged from 0 to 0.96 and specificities from 0 to 1.00. For all imaging methods the estimated summary sensitivity and specificity point was 0.47 (95% confidence interval (CI) 0.40 to 0.53) and 0.88 (95% CI 0.84 to 0.92), respectively. In a cohort of 1000 tooth surfaces with a prevalence of enamel caries of 63%, this would result in 337 tooth surfaces being classified as disease free when enamel caries was truly present (false negatives), and 43 tooth surfaces being classified as diseased in the absence of enamel caries (false positives). Meta-regression indicated that measures of accuracy differed according to the imaging method (Chi²(4) = 32.44, P < 0.001), with the highest sensitivity observed for CBCT, and the highest specificity observed for analogue radiographs. None of the specified potential sources of heterogeneity were able to explain the variability in results. No studies included restored teeth in their sample or reported the inclusion of sealants. We rated the certainty of the evidence as low for sensitivity and specificity and downgraded two levels in total for risk of bias due to limitations in the design and conduct of the included studies, indirectness arising from the in vitro studies, and the observed inconsistency of the results.

AUTHORS' CONCLUSIONS

The design and conduct of studies to determine the diagnostic accuracy of methods to detect and diagnose caries in situ are particularly challenging. Low-certainty evidence suggests that imaging for the detection or diagnosis of early caries may have poor sensitivity but acceptable specificity, resulting in a relatively high number of false-negative results with the potential for early disease to progress. If left untreated, the opportunity to provide professional or self-care practices to arrest or reverse early caries lesions will be missed. The specificity of lesion detection is however relatively high, and one could argue that initiation of non-invasive management (such as the use of topical fluoride), is probably of low risk. CBCT showed superior sensitivity to analogue or digital radiographs but has very limited applicability to the general dental practitioner. However, given the high-radiation dose, and potential for caries-like artefacts from existing restorations, its use cannot be justified in routine caries detection. Nonetheless, if early incidental carious lesions are detected in CBCT scans taken for other purposes, these should be reported. CBCT has the potential to be used as a reference standard in diagnostic studies of this type. Despite the robust methodology applied in this comprehensive review, the results should be interpreted with some caution due to shortcomings in the design and execution of many of the included studies. Future research should evaluate the comparative accuracy of different methods, be undertaken in a clinical setting, and focus on minimising bias arising from the use of imperfect reference standards in clinical studies.

Distributed Deep Fusion Predictor for a Multi-Sensor System Based on Causality Entropy

Trend prediction based on sensor data in a multi-sensor system is an important topic. As the number of sensors increases, we can measure and store more and more data. However, the increase in data has not effectively improved prediction performance. This paper focuses on this problem and presents a distributed predictor that can overcome unrelated data and sensor noise: First, we define the causality entropy to calculate the measurement's causality. Then, the series causality coefficient (SCC) is proposed to select the high causal measurement as the input data. To overcome the traditional deep learning network's over-fitting to the sensor noise, the Bayesian method is used to obtain the weight distribution characteristics of the sub-predictor network. A multi-layer perceptron (MLP) is constructed as the fusion layer to fuse the results from different sub-predictors. The experiments were implemented to verify the effectiveness of the proposed method by meteorological data from Beijing. The results show that the proposed predictor can effectively model the multi-sensor system's big measurement data to improve prediction performance.

Can smartphone technology be used to support an effective home exercise intervention to prevent falls amongst community dwelling older adults?: the TOGETHER feasibility RCT study protocol

INTRODUCTION

Falls have major implications for quality of life, independence and cost to the health service. Strength and balance training has been found to be effective in reducing the rate/risk of falls, as long as there is adequate fidelity to the evidence-based programme. Health services are often unable to deliver the evidence-based dose of exercise and older adults do not always sufficiently adhere to their programme to gain full outcomes. Smartphone technology based on behaviour-change theory has been used to support healthy lifestyles, but not falls prevention exercise. This feasibility trial will explore whether smartphone technology can support patients to better adhere to an evidence-based rehabilitation programme and test study procedures/outcome measures.

METHODS AND ANALYSIS

A two-arm, pragmatic feasibility randomised controlled trial will be conducted with health services in Manchester, UK. Seventy-two patients aged 50+years eligible for a falls rehabilitation exercise programme from two community services will receive: (1) standard service with a smartphone for outcome measurement only or (2) standard service plus a smartphone including the motivational smartphone app. The primary outcome is feasibility of the intervention, study design and procedures. The secondary outcome is to compare standard outcome measures for falls, function and adherence to instrumented versions collected using smartphone. Outcome measures collected include balance, function, falls, strength, fear of falling, health-related quality of life, resource use and adherence. Outcomes are measured at baseline, 3 and 6-month post-randomisation. Interviews/focus groups with health professionals and participants further explore feasibility of the technology and trial procedures. Primarily analyses will be descriptive.

ETHICS AND DISSEMINATION

The study protocol is approved by North West Greater Manchester East Research Ethics Committee (Rec ref:18/NW/0457, 9/07/2018). User groups and patient representatives were consulted to inform trial design, and are involved in study recruitment. Results will be reported at conferences and in peer-reviewed publications. A dissemination event will be held in Manchester to present the results of the trial. The protocol adheres to the recommended Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) checklist.

TRIAL REGISTRATION NUMBER

ISRCTN12830220; Pre-results.

CropDeep: The Crop Vision Dataset for Deep-Learning-Based Classification and Detection in Precision Agriculture

Intelligence has been considered as the major challenge in promoting economic potential and production efficiency of precision agriculture. In order to apply advanced deep-learning technology to complete various agricultural tasks in online and offline ways, a large number of crop vision datasets with domain-specific annotation are urgently needed. To encourage further progress in challenging realistic agricultural conditions, we present the CropDeep species classification and detection dataset, consisting of 31,147 images with over 49,000 annotated instances from 31 different classes. In contrast to existing vision datasets, images were collected with different cameras and equipment in greenhouses, captured in a wide variety of situations. It features visually similar species and periodic changes with more representative annotations, which have supported a stronger benchmark for deep-learning-based classification and detection. To further verify the application prospect, we provide extensive baseline experiments using state-of-the-art deep-learning classification and detection models. Results show that current deep-learning-based methods achieve well performance in classification accuracy over 99%. While current deep-learning methods achieve only 92% detection accuracy, illustrating the difficulty of the dataset and improvement room of state-of-the-art deep-learning models when applied to crops production and management. Specifically, we suggest that the YOLOv3 network has good potential application in agricultural detection tasks.

Semi-Supervised Segmentation Framework Based on Spot-Divergence Supervoxelization of Multi-Sensor Fusion Data for Autonomous Forest Machine Applications

In this paper, a novel semi-supervised segmentation framework based on a spot-divergence supervoxelization of multi-sensor fusion data is proposed for autonomous forest machine (AFMs) applications in complex environments. Given the multi-sensor measuring system, our framework addresses three successive steps: firstly, the relationship of multi-sensor coordinates is jointly calibrated to form higher-dimensional fusion data. Then, spot-divergence supervoxels representing the size-change property are given to produce feature vectors covering comprehensive information of multi-sensors at a time. Finally, the Gaussian density peak clustering is proposed to segment supervoxels into sematic objects in the semi-supervised way, which non-requires parameters preset in manual. It is demonstrated that the proposed framework achieves a balancing act both for supervoxel generation and sematic segmentation. Comparative experiments show that the well performance of segmenting various objects in terms of segmentation accuracy (F-score up to 95.6%) and operation time, which would improve intelligent capability of AFMs.

Herbst appliance with skeletal anchorage versus dental anchorage in adolescents with Class II malocclusion: study protocol for a randomised controlled trial

Background

The Herbst appliance is an orthodontic appliance that is used for the correction of class II malocclusion with skeletal discrepancies. Research has shown that this is effective. However, a potential harm is excessive protrusion of the lower front teeth. This is associated with gingival recession, loss of tooth support, and root resorption. This trial evaluates a method of reducing this problem.

Methods/Design

The study is a single-center, randomised, assessor-blinded, superiority clinical trial with parallel 1:1 allocation. Male and female young people (10–14 years old) with prominent front teeth (class II, division 1) will be treated in one orthodontic clinic. Group 1 will be treated with the conventional Herbst appliance with dental anchorage and group 2 with the Herbst appliance with indirect skeletal anchorage for 12 months. The primary objective will be to compare the proclination of the lower incisors between the Herbst appliance with dental anchorage and skeletal anchorage. Secondary objectives will be to evaluate the changes occurring between the groups in the mandible, maxilla, lower and upper molars, and in gingival recession and root resorption at the end of the treatment. Additionally, the young patient’s experience using the appliances will be assessed. The primary outcome measure will be the amount of lower incisor proclination at the end of treatment. This will be assessed by cone-beam computed tomography (CBCT) superimposition. Secondary outcome measures will be the changes in the mandible, maxilla, lower and upper molars at the end of treatment assessed by tomography superimposition and the young patient’s experience using the appliances assessed by self-reported questionnaires and semi-structured interviews. The randomisation method will be blocked randomisation, using software to generate a randomised list. The allocation concealment will be done in opaque envelopes numbered from 1 to 40 containing the treatment modality. The randomisation will be implemented by the secretary of the Department of Orthodontics of Rio de Janeiro State University before the beginning of the study. The patients and the orthodontists who will treat the patients cannot be blinded, as they will know the type of appliance used. The technician who will take the CBCT image and the data analyst will be blinded to patients’ group allocation.

Discussion

If this new intervention is effective, the findings can change orthodontic practice and may also be relevant to other forms of treatment in which appliances are fixed to the bones of the jaws. However, if the bone anchoring is not effective, the trial will provide much needed information on the use of this comparatively new development.

Trial registration

ClinicalTrials.gov, protocol ID: NCT0241812. Registered on 26 March 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2297-5) contains supplementary material, which is available to authorized users.

An evaluation of the bootstrap for model validation in mixture models

Bootstrapping has been used as a diagnostic tool for validating model results for a wide array of statistical models. Here we evaluate the use of the non-parametric bootstrap for model validation in mixture models. We show that the bootstrap is problematic for validating the results of class enumeration and demonstrating the stability of parameter estimates in both finite mixture and regression mixture models. In only 44% of simulations did bootstrapping detect the correct number of classes in at least 90% of the bootstrap samples for a finite mixture model without any model violations. For regression mixture models and cases with violated model assumptions, the performance was even worse. Consequently, we cannot recommend the non-parametric bootstrap for validating mixture models. The cause of the problem is that when resampling is used influential individual observations have a high likelihood of being sampled many times. The presence of multiple replications of even moderately extreme observations is shown to lead to additional latent classes being extracted. To verify that these replications cause the problems we show that leave-k-out cross-validation where sub-samples taken without replacement does not suffer from the same problem.

A Novel Group Decision-Making Method Based on Sensor Data and Fuzzy Information

Algal bloom is a typical phenomenon of the eutrophication of rivers and lakes and makes the water dirty and smelly. It is a serious threat to water security and public health. Most scholars studying solutions for this pollution have studied the principles of remediation approaches, but few have studied the decision-making and selection of the approaches. Existing research uses simplex decision-making information which is highly subjective and uses little of the data from water quality sensors. To utilize these data and solve the rational decision-making problem, a novel group decision-making method is proposed using the sensor data with fuzzy evaluation information. Firstly, the optimal similarity aggregation model of group opinions is built based on the modified similarity measurement of Vague values. Secondly, the approaches' ability to improve the water quality indexes is expressed using Vague evaluation methods. Thirdly, the water quality sensor data are analyzed to match the features of the alternative approaches with grey relational degrees. This allows the best remediation approach to be selected to meet the current water status. Finally, the selection model is applied to the remediation of algal bloom in lakes. The results show this method's rationality and feasibility when using different data from different sources.

Understanding clinical prediction models as 'innovations': a mixed methods study in UK family practice

Background

Well-designed clinical prediction models (CPMs) often out-perform clinicians at estimating probabilities of clinical outcomes, though their adoption by family physicians is variable. How family physicians interact with CPMs is poorly understood, therefore a better understanding and framing within a context-sensitive theoretical framework may improve CPM development and implementation. The aim of this study was to investigate why family physicians do or do not use CPMs, interpreting these findings within a theoretical framework to provide recommendations for the development and implementation of future CPMs.

Methods

Mixed methods study in North West England that comprised an online survey and focus groups.

Results

One hundred thirty eight respondents completed the survey, which found the main perceived advantages to using CPMs were that they guided appropriate treatment (weighted rank [r] = 299; maximum r = 414 throughout), justified treatment decisions (r = 217), and incorporated a large body of evidence (r = 156). The most commonly reported barriers to using CPMs were lack of time (r = 163), irrelevance to some patients (r = 161), and poor integration with electronic health records (r = 147). Eighteen clinicians participated in two focus groups (i.e. nine in each), which revealed 13 interdependent themes affecting CPM use under three overarching domains: clinician factors, CPM factors and contextual factors. Themes were interdependent, indicating the tensions family physicians experience in providing evidence-based care for individual patients.

Conclusions

The survey and focus groups showed that CPMs were valued when they supported clinical decision making and were robust. Barriers to their use related to their being time-consuming, difficult to use and not always adding value. Therefore, to be successful, CPMs should offer a relative advantage to current working, be easy to implement, be supported by training, policy and guidelines, and fit within the organisational culture.

A review of statistical updating methods for clinical prediction models

A clinical prediction model is a tool for predicting healthcare outcomes, usually within a specific population and context. A common approach is to develop a new clinical prediction model for each population and context; however, this wastes potentially useful historical information. A better approach is to update or incorporate the existing clinical prediction models already developed for use in similar contexts or populations. In addition, clinical prediction models commonly become miscalibrated over time, and need replacing or updating. In this article, we review a range of approaches for re-using and updating clinical prediction models; these fall in into three main categories: simple coefficient updating, combining multiple previous clinical prediction models in a meta-model and dynamic updating of models. We evaluated the performance (discrimination and calibration) of the different strategies using data on mortality following cardiac surgery in the United Kingdom: We found that no single strategy performed sufficiently well to be used to the exclusion of the others. In conclusion, useful tools exist for updating existing clinical prediction models to a new population or context, and these should be implemented rather than developing a new clinical prediction model from scratch, using a breadth of complementary statistical methods.

Experimental designs for detecting synergy and antagonism between two drugs in a pre-clinical study

The identification of synergistic interactions between combinations of drugs is an important area within drug discovery and development. Pre-clinically, large numbers of screening studies to identify synergistic pairs of compounds can often be ran, necessitating efficient and robust experimental designs. We consider experimental designs for detecting interaction between two drugs in a pre-clinical in vitro assay in the presence of uncertainty of the monotherapy response. The monotherapies are assumed to follow the Hill equation with common lower and upper asymptotes, and a common variance. The optimality criterion used is the variance of the interaction parameter. We focus on ray designs and investigate two algorithms for selecting the optimum set of dose combinations. The first is a forward algorithm in which design points are added sequentially. This is found to give useful solutions in simple cases but can lack robustness when knowledge about the monotherapy parameters is insufficient. The second algorithm is a more pragmatic approach where the design points are constrained to be distributed log-normally along the rays and monotherapy doses. We find that the pragmatic algorithm is more stable than the forward algorithm, and even when the forward algorithm has converged, the pragmatic algorithm can still out-perform it. Practically, we find that good designs for detecting an interaction have equal numbers of points on monotherapies and combination therapies, with those points typically placed in positions where a 50% response is expected. More uncertainty in monotherapy parameters leads to an optimal design with design points that are more spread out.

Investigation of the robustness of two models for assessing synergy in pre-clinical drug combination studies

Pre-clinical studies may be used to screen for synergistic combinations of drugs. The types of in vitro assays used for this purpose will depend upon the disease area of interest. In oncology, one frequently used study measures cell line viability: cells placed into wells on a plate are treated with doses of two compounds, and cell viability is assessed from an optical density measurement corrected for blank well values. These measurements are often transformed and analysed as cell survival relative to untreated wells. The monotherapies are assumed to follow the Hill equation with lower and upper asymptotes at 0 and 1, respectively. Additionally, a common variance about the dose-response curve may be assumed. In this paper, we consider two models for incorporating synergy parameters. We investigate the effect of different models of biological variation on the assessment of synergy from both of these models. We show that estimates of the synergy parameters appear to be robust, even when estimates of the other model parameters are biased. Using untransformed measurements provides better coverage of the 95% confidence intervals for the synergy parameters than using transformed measurements, and the requirement to fit the upper asymptote does not cause difficulties. Assuming homoscedastic variances appears to be robust. The added complexity of determining and fitting an appropriate heteroscedastic model does not seem to be justified.

Designing exploratory cancer trials using change in tumour size as primary endpoint

In phase III cancer clinical trials, overall survival is commonly used as the definitive endpoint. In phase II clinical trials, however, more immediate endpoints such as incidence of complete or partial response within 1 or 2 months or progression-free survival (PFS) are generally used. Because of the limited ability to detect change in overall survival with response, the inherent variability of PFS and the long wait for progression to be observed, more informative and immediate alternatives to overall survival are desirable in exploratory phase II trials. In this paper, we show how comparative trials can be designed and analysed using change in tumour size as the primary endpoint. The test developed is based on the framework of score statistics and will formally incorporate the information of whether patients survive until the time at which change in tumour size is assessed. Using an example in non-small cell lung cancer, we show that the sample size requirements for a trial based on change in tumour size are favourable compared with alternative randomized trials and demonstrate that these conclusions are robust to our assumptions.

Estimation strategies for reacting to the identification of an association between the genome and adverse drug reactions

The availability of high-resolution genetic profiling raises the possibility, during the course of a drug development program, of discovering a subset of patients at particular risk of an adverse drug reaction who might be excluded from subsequent randomization into studies and identified as unsuitable for post-licensing use. Such methods depend on the estimation of the risk of adverse drug reactions for patients with differing genetic profiles followed by an assessment of the risks and benefits of their exposure to the drug. In this paper we explore the performance of a number alternative statistical methods for the estimation of risk in terms of the success of the subsequent exclusion rules. The approaches were evaluated using a single-nucleotide polymorphism dataset concerning HIV patients at risk of hypersensitivity to the drug abacavir. Overall we found that a method based on LASSO performed better than the alternatives that we studied, which included a decision-theoretic Bayesian approach, and that its performance suggested suitability for its prospective implementation.

Laboratory measurements of the volatilization of PCBs from amended dredged material

Since 1997, over 6 million cubic meters of material dredged from the navigation channels of NY/NJ Harbor has been amended with Portland cement and then used as fill and capping material at landfill and brownfield sites in New Jersey, New York, and Pennsylvania. Previous studies have determined that polychlorinated biphenyls (PCBs) will volatilize from this material as it dries. In the present study, time constants for the decay of the volatilization rate were determined taking into account the degree of stabilization. The experiments were conducted in a laminar flow flux chamber in which air was drawn past the dredged material and then through a polyurethane foam (PUF), sample matrix. The concentration of PCBs on the PUF found at various time increments at the downstream end of the chamber was compared to that found for the same time increments in a PUF installed in an air sampler at the upstream end of the chamber in order to calculate the flux. The time constant determined for raw dredged material was about 4 times greater than material stabilized with 8% Portland cement. The average time constants for the decay of flux rates from raw dredged material were 56, 67, and 60h for the di-, tri-, and tetra-chlorinated homologues, respectively. These times decreased with increasing proportion of Portland cement in the mixture. When stabilized with 8% Portland cement, the average time constants were 14, 13, and 19h, respectively. The effects of temperature on PCB flux rate were also investigated. The results suggest that a 3 degrees C temperature increase will more than double the flux rate.

Nutrient recovery and biodegradation of inedible tomato plant residues by activated sludge cultures and Phanerochaete chrysosporium

The biodegradation of inedible biomass and the recovery of nutrients from hydroponically grown tomato plant material were investigated under various growth conditions of activated sludge and the fungus Phanerochaete chrysosporium. The experiments were carried out in shaker flasks at three incubation temperatures (25 degrees C, 40 degrees C, and 60 degrees C for the activated sludge and 25 degrees C, 40 degrees C, and 50 degrees C for the fungi) with heat-pretreated samples at 150 degrees C for 30 min, and without pretreatment of the inedible residues. Under the experimental conditions tested, both cultures exhibited similar performance in terms of solids reduction and nutrient recovery. Solids reduction as high as 70% was obtained in both systems. Most of the solids degradation occurred the first 16 days of incubation. Cellulose degradation reached about 90% but no significant reduction in the solids lignin content was observed. Recovery of nitrogen (as NO2-N and NO3-N) and other micronutrients was sufficiently high and was accompanied by an average 70% reduction in COD, indicating that the final effluent is suitable for hydroponic plant growth. Incubation temperature had a minimal effect on solids degradation but appeared to influence the leachability of certain nutrients.

Methods for conducting sensitivity analysis of trials with potentially nonignorable competing causes of censoring

We consider inference for the treatment-arm mean difference of an outcome that would have been measured at the end of a randomized follow-up study if, during the course of the study, patients had not initiated a nonrandomized therapy or dropped out. We argue that the treatment-arm mean difference is not identified unless unverifiable assumptions are made. We describe identifying assumptions that are tantamount to postulating relationships between the components of a pattern-mixture model but that can also be interpreted as imposing restrictions on the cause-specific censoring probabilities of a selection model. We then argue that, although sufficient for identification, these assumptions are insufficient for inference due to the curse of dimensionality. We propose reducing dimensionality by specifying semiparametric cause-specific selection models. These models are useful for conducting a sensitivity analysis to examine how inference for the treatment-arm mean difference changes as one varies the magnitude of the cause-specific selection bias over a plausible range. We provide methodology for conducting such sensitivity analysis and illustrate our methods with an analysis of data from the AIDS Clinical Trial Group (ACTG) study 002.

Kinetics of the alkaline hydrolysis of nitrocellulose

Cellulose nitrate (nitrocellulose) is an explosive solid substance used in large quantities in various formulations of rocket and gun propellants. Safe destruction of nitrocellulose can be achieved by alkaline hydrolysis, which converts it to biodegradable products that can then be treated by conventional biological processes. The kinetics of the alkaline hydrolysis of munitions-grade nitrocellulose in sodium hydroxide solutions were investigated in completely mixed batch reactors. Experiments were conducted using solutions of alkaline strength ranging from 0.1 to 15% by mass and temperatures in the range of 30 to 90 degrees C. Regression analysis of the kinetic data revealed that alkaline hydrolysis of nitrocellulose is of the order 1.0 and 1.5 with respect to nitrocellulose and hydroxide concentration, respectively. The activation energy of the hydrolysis reaction was found to be 100.9 kJ/mol with a preexponential Arrhenius constant of 4.73 x 10(13). Nitrite and nitrate, in a 3:1 ratio, were the primary nitrogen species present in the posthydrolysis solution. The kinetic information is pertinent to the development and optimization of nitrocellulose chemical-biological treatment systems.

Synthesis and autoxidation of new tetracyclic 9H,10H-indolizino[1,2-b]indole-1-ones

The new tetracyclic 9H,10H-indolizino[1,2-b]indole-1-one derivatives (7a-d, 7ea, 7eb) have been synthesized by modified Fischer indole synthesis from the enol ether of 2,5-dihydroxy-7-methyl-6-cyano-indolizine (3) and arylhydrazines (4a-g). Attempted N-methylation of 7a-d produced a series of autoxidized products including 10-hydroperoxy-1-methoxyindolizino[1,2-b]indole (9a-d) as the major product accompanied with methylperoxides (10a-d and 11a-d) and 2-formyl-3-(pyridine-2-yl)indole (12a, 12c) derivatives as the minor products. A plausible mechanism of the autoxidation is postulated based on the isolation of some intermediates. The reaction is thought to proceed through azaenolate/enamine intermediates following a novel type of autoxidation.

Isolation and identification of novel protein kinase genes from the round-spotted pufferfish (Tetraodon fluviatilis) genomic DNA

The round-spotted pufferfish Tetraodon fluviatilis has a genome size of 380 Mb which is slightly smaller than that of another pufferfish, Fugu rubripes rubripes (Fugu). Due to their compact genome and small introns, both pufferfishes have been proposed as model organisms for genome studies. In this study, we have used genomic DNA as template to perform PCR to screen for protein kinase (pk) genes. Forty-one T. fluviatilis pk genes encoding 7 receptor tyrosine kinases, 14 nonreceptor tyrosine kinases, 16 serine/threonine kinases, 1 dual kinase and 3 novel kinases have been identified. The success of this approach depends on the size and location of the introns. Most of the identified pk gene fragments contain introns, ranging from 71 to 300 bp, with an average of 120 bp. It is noteworthy that the intron/exon boundaries of certain genes which belong to the same family are identical. We also analyzed by specific RT-PCR primers the expression profile of those 3 novel genes as well as some selected pk genes in a variety of tissues. We found that erbB3, pku a, mrk, CaMK I, CaMKIIgamma, and two novel kinase genes (133 and 3-26) are expressed in all tissues examined. However, the novel clone 146 is strongly expressed in the brain and weakly in the intestine, kidney and heart.

The prevalence of cognitive impairment among nursing home residents in Taipei, Taiwan

A random sample of nursing home residents over 65 years of age were interviewed. Two hundred ninety-two participants received the Short Portable Mental Status Questionnaire. Two hundred eleven were unable to answer the questionnaire, but their caregivers provided information about their daily activities and performance ability. We found that 255 (50.9%) fit our criteria of cognitive impairment and 236 (47.7%) had both impaired cognition and impaired performance in activities of daily living. Similar to statistics in the US, the prevalence of cognitive impairment in Taipei nursing home residents was much higher than that observed in the community elderly and probably in Taiwan as well. Therefore, public health care policy for cognitively impaired elderly in Taiwan should not simply rely on data from community studies.

Synthesis of biotinylated glyfoline for immunoelectron microscopic localization

Antineoplastic glyfoline (1) has potent antitumor efficacy against various murine and human solid tumors. To elucidate the actual mechanism of action, we synthesized biotinylated glyfoline (B-Gly) and used it for the visualization of glyfoline-binding sites in nasopharyngeal carcinoma (NPC) cells. Under the electron microscope (EM), after cells were incubated for 6-36 h, the reaction products of anti-B-Gly were seen on some areas of the external cell surface and on the outer and inner membranes of the mitochondria. Pure EM morphology of NPC cells after glyfoline treatment revealed the similar morphological change of mitochondria. These findings indicate that the binding site of glyfoline in NPC is the inner membrane of the mitochondria, suggesting that B-Gly can be used as a marker for glyfoline localization.

Alien hand syndrome: report of two cases

Alien hand syndrome (AHS) refers to the occurrence of apparently purposeful movements in the hand which are independent of volitional control. Two subtypes of AHS have been proposed: frontal AHS, with grasp reflex and compulsive manipulation of tools by the dominant hand, and callosal AHS, which occurs in the nondominant hand and is characterized mainly by intermanual conflict. Here, we report two cases of frontal-type alien hand syndrome with symptoms of reflexive grasping, impulsive groping, and apraxia (in case 1), and compulsive manipulation of tools (in case 2). Brain computed tomography revealed a left anterior cerebral artery (ACA) territory infarct and multiple small infarcts of both hemispheres in patient 1 and a left ACA infarct in patient 2. The involuntary movements were bothersome to these patients in their daily activities. Both patients attended conventional physical and occupational therapies, and patient 2 received additional biofeedback training. Follow-up studies showed the spontaneous grasping behavior was still present in patient 1 and AHS had subsided in patient 2. We also describe a potentially effective technique involving biofeedback for patients with alien hand syndrome.

Synthesis and structure-activity relationships of potential anticancer agents: alkylcarbamates of 3-(9-acridinylamino)-5-hydroxymethylaniline

A series of potential 9-anilinoacridine antitumor agents, 3-(9-acridinylamino)-5-hydroxymethylaniline (AHMA) derivatives with monosubstituent at C4' and disubstituents at C4' and C5' of the acridine ring and their alkylcarbamates, were synthesized for evaluation of their antitumor activity. A structure-activity relationship (SAR) study showed that the AHMA-alkylcarbamates were more potent than their corresponding parent AHMA compounds. In addition, the cytotoxicity of the AHMA-alkylcarbamate decreased with increasing length and size of the alkyl function. Among these compounds, AHMA-ethylcarbamate (18) and 4'-methyl-5'-dimethylaminoethylcarboxamido-AHMA-ethylcarb amate (34) possess potent cytotoxicity on the inhibition of human leukemic HL-60 cell growth in culture. Further in vivo studies of these compounds displayed significant anticancer therapeutic effects in mice bearing sarcoma 180, Lewis lung carcinoma, and P388 leukemia.

Differential paclitaxel-induced cytotoxicity in rodent and human hepatoma cell lines

Hepatoma is the leading cause of death in male cancer patients in Taiwan. In this study, we examined the effect of Paclitaxel on the in vitro growth of 2 rodent and 4 human hepatoma cell lines. Differential Paclitaxel-induced cytotoxicity was observed among hepatoma cell lines. In Paclitaxel-sensitive Hep3B and N1S1 cells, Paclitaxel-induced cytotoxicity was dose- and time-dependent. The effective doses of Paclitaxel were in the range 0.1-1.0 microM. Flow cytometric analysis showed that Paclitaxel-treated hepatoma cells were arrested in G2-M phases prior to apoptosis. In addition, growth inhibition by Paclitaxel was accompanied by an increase in the expression of proliferating cell nuclear antigen (PCNA) in hepatoma cells. For Paclitaxel-resistant hepatoma cells, cytostatic response and/or polyploidization was observed. Our results indicated that two thirds of the hepatoma cell lines examined showed some degree of resistance to Paclitaxel treatment in vitro. The expression of p53 gene had no direct effect on Paclitaxel-induced cytotoxicity. The expression of PCNA and the development of polyploidization appear to be good markers for measuring Paclitaxel response. These findings suggest that Paclitaxel alone appears to by cytostatic to hepatoma cells, combination of Paclitaxel with other chemotherapeutic agents may show better cytotoxic effects.

Serum hepatocyte growth factor level associate with gastric cancer progression

We have measured serum HGF levels from 80 gastric cancer patients and 51 normal subjects by enzyme-linked immunosorbent assay. The results showed that the mean value of serum HGF level in gastric cancer patients was significantly higher than in normal subjects (0.30 +/- 0.02 vs 0.22 +/- 0.05 ng/ml; p = 0.005). The increase was stage related. Patients with serum HGF < or = 0.30 ng/ml survived longer than those with serum HGF > 0.30 ng/ml (p = 0.02). These data suggest that HGF involve in progression of gastric cancer.

Cyclopent[a]anthraquinones as DNA intercalating agents with covalent bond formation potential: synthesis and biological activity

A series of mitomycin C (MMC) analogues, namely cyclopentanthraquinone derivatives, were synthesized via Diels-Alder cyclization of naphthoquinone with 1-vinylcyclopent-1-enes. These new compounds are planar structures, like MMC, and bear an aziridine ring and a methyl carbamate side chain. After bioreduction, they are anticipated to be capable of intercalating into double-stranded DNA and bind covalently. Structure-activity relationships were studied. Of these compounds, 2,3-aziridino-4-[[(methylamino)carbonyl]methyl] cyclopent[alpha]anthracene-6,11-dione (4) was shown to have inhibitory activity against several leukemic and solid tumor cell lines. Mice (BDF1) bearing Lewis lung adenocarcinoma were treated with 4 and MMC (i.p., QD x 5). At a dose of 30.0 mg/kg, compound 4 was as effective as MMC (0.8 mg/kg). Compound 4 appears to be less toxic than MMC. DNA unwinding assay indicated that 4 is able to intercalate into DNA double strands and is also a topoisomerase II inhibitor.

9-substituted acridine derivatives with long half-life and potent antitumor activity: synthesis and structure-activity relationships

A series of DNA-intercalating 9-anilinoacridines, namely 9-phenoxyacridines, 9-(phenylthio)acridines, and 9-(3',5'-disubstituted anilino)acridines, were synthesized as potential antitumor agents with inhibitory effects on DNA topoisomerase II. Unlike amsacrine (m-AMSA), these agents were designed to avoid the oxidative metabolic pathway. These acridine derivatives were, therefore, expected to have long half-life in plasma. Both 9-phenoxyacridines and 9-(phenylthio)acridines were found to have moderate cytotoxicity against mouse leukemia L1210 and human leukemic HL-60 cell growth in culture. Among 9-(3',5'-disubstituted anilino)acridines, 3-(9-acridinylamino)-5-(hydroxymethyl)aniline (AHMA) was found to be a potent topoisomerase II inhibitor and exhibited significant antitumor efficacy both in vitro and in vivo. Chemotherapy of solid-tumor-bearing mice with 10, 10, and 5 mg/kg (QD x 4, ip) AHMA, VP-16, and m-AMSA, respectively, resulted in more tumor volume reduction by AHMA than by VP-16 or m-AMSA for E0771 mammary adenocarcinoma and B-16 melanoma. For Lewis lung carcinoma, AHMA was as potent as VP-16 but more active than m-AMSA. Structure-activity relationships of AHMA derivatives are discussed.

Synthesis of the acridone alkaloids glyfoline and congeners. Structure-activity relationship studies of cytotoxic acridones

Glyfoline (4, 1,6-dihydroxy-10-methyl-2,3,4,5-tetramethoxyacridin-9-one) and its congeners were synthesized for evaluation of their cytotoxicity. A detailed structure-activity relationships (SAR) of these acridone derivatives were also studied. To study the SAR of glyfoline analogues, substituent(s) at C-1 and C-6 and at the heterocyclic nitrogen of glyfoline nucleus were modified. Nitro- and amino-substituted glyfoline analogues were also synthesized to study the effects of substituent(s) (electron-withdrawing vs electron-donating) on their cytotoxicity. These compounds were synthesized via the Ullmann condensation of anthranilic acids with iodobenzenes or 2-chlorobenzoic acids with aniline derivatives. The SAR studies showed that 1-hydroxy-9-acridones were more active than their 1-OMe derivatives against cell growth of human leukemic HL-60 cells in culture. Replacement of NMe of glyfoline with NH or N(CH2)2NEt2 resulted in either total loss or dramatic reduction of cytotoxicity. Glyfoline congeners with nitro function at the A-ring were inactive, while compounds with amino substituent were shown to be cytotoxic in vitro.

Inhibitory effects of isoquinoline-type alkaloids on leukemic cell growth and macromolecule biosynthesis

A number of benzylisoquinoline alkaloids of plants indigenous to Taiwan were isolated and purified and their chemical structures were determined. These compounds, namely benzyltetrahydroisoquinolines or their N-oxides, aporphines, oxoaporphines and 1-N, N-dimethylaminoethylphenanthrenes or their N-oxides, were studied for their potency in inhibiting precursor incorporation into DNA, RNA and protein. Inhibition of murine leukemic L1210 and human leukemic CCRF-CEM and HL-60 cell growth was also examined. Of the compounds evaluated for cell growth inhibition, (+-)-N-methylcoclaurine(3), (-)-norannuradhapurine HBr(19), oxoglaucine (23), dicentrine methine (27) and 1-(N-methyl-N-hydroxyaminoethyl)-3, 4-methylenedioxy-7-methoxyphenanthrene (28) showed an IC50 less than 10 microM.

Chemical synthesis and biological activities of 5-deazaaminopterin analogues bearing substituent(s) at the 5- and/or 7-position(s)

Condensation of cyanothioacetamide (4) with ethyl alpha-(ethoxymethylene)acetoacetate (5b), ethyl 4-ethoxy-2-(ethoxymethylene)-3-oxobutanoate (5c), ethyl 2-(ethoxymethylene)-3-oxo-4-phenylpropanoate (5d) afforded exclusively the corresponding 6-substituted pyridines (6b-d). Cyclization of 4 with 3-carbethoxybutane-2,4-dione (5e) gave 3-cyano-5-(ethoxycarbonyl)-4,6-dimethylpyridine-2(1H)-thione (6e), whereas reaction of 4 with 3-carbethoxy-1-phenylpropane-1,3-dione (5f) yielded two products, 3-cyano-5-(ethoxycarbonyl)-4-methyl-6-phenylpyridine-2(1H)-thione (6f) and the 6-methyl-4-phenyl isomer 6g. The structural assignments for 6f and 6g are made on the basis of 1H and 13C NMR spectral analyses of the 2-(methylthio)nicotinates (7f,g) prepared from 6f and 6g by treatment with MeI/K2CO3. Nicotinates 7b,d-g were converted into their corresponding 2,4-diaminopyrido[2,3-d]pyrimidines 12b,d-g in five steps, via reduction, protection, oxidation, condensation with guanidine, and deprotection. The 7-mono- and 5,7-disubstituted-5-deazaaminopterins (1b,d-g) were prepared from the respective pyrido[2,3-d]pyrimidines 12b,d-g. Preliminary biological studies showed that 7-methyl and 5,7-dimethyl analogues (1b and 1e) were less active than methotrexate against human leukemic HL-60 and murine L-1210 cells in tissue culture. Compound 1e produced an ILS of 71% at 100 mg/kg per day X 5 (ip) in BDF mice inoculated ip with 10(6) L-1210 cells.

Anti-fertility and other actions of gossypol analogues

From a series of gossypol derivatives studied, we conclude that the carbonyl groups of gossypol are needed for inhibition of erythrocyte anion transport and the hydroxy groups affect but are not essential to that inhibition. In an in vitro mouse erythroleukemia cytocidal assay, the most active compounds were gossypol and apogossypol. The latter was not active in the inhibition of erythrocyte anion transport or in a spermicidal assay. Of the more simple structures related to gossypol, those that were active in the cytocidal and spermicidal assays were bi-aromatic, linked by a 1- and not a 4-carbon chain and had free phenolic hydroxyl groups. These results are included in a discussion of the specificity and mechanism of action of gossypol.

Synthesis and biological activities of 5-deaza analogues of aminopterin and folic acid

N-[p-[[(2,4-Diaminopyrido[2,3-d]pyrimidin-6-yl)methyl] amino]benzoyl]-L-glutamic acid (1a, 5-deazaaminopterin) and the 5-methyl analogue (1b) were synthesized in 14 steps from 5-cyanouracil (4a) and 5-cyano-6-methyluracil (4b), respectively, by exploitation of the novel pyrimidine to pyrido[2,3-d]pyrimidine ring transformation reaction. The 5-cyanouracils 4 were treated with chloromethyl methyl ether to the 1,3-bis(methoxymethyl)uracils (5, which were treated with malononitrile in NaOEt/EtOH to give the pyrido[2,3-d]pyrimidines 6. Diazotization of 6 in concentrated HCl afforded the 7-chloro derivatives 8 in high yield. After reduction of 8, the 7-unsubstituted products 9 were reduced in the presence of Ac2O and the products, 6-(acetamidomethyl)pyridopyrimidines 10, were converted into the 6-acetoxymethyl derivatives 12 via nitrosation. After removal of the N-methoxymethyl groups from 12, the 6-(acetoxymethyl)pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones 14 were converted into 2,4-diamino-6-(hydroxymethyl)pyrido[2,3-d]pyrimidine (15a) and its 5-methyl analogue 15b by the silylation-amination procedure. Compounds 15 were brominated to the 6-bromomethyl derivatives 16, which were treated with diethyl (p-aminobenzoyl)-L-glutamate, and the products 17 were saponified to afford 5-deazaaminopterin (1a) and its 5-methyl analogue 1b. Compound 1b was also prepared by an alternative procedure in 10 steps from cyanothioacetamide and ethyl beta-(ethoxymethylene)acetoacetate via 2,4-diamino-6-(hydroxymethyl)-5-methylpyrido[2,3-d]pyrimidine (15b). 5-Deaza-5-methylfolic acid (2) was also prepared in four steps from 15b. The aminopterine analogues 1 showed significant anticancer activity in vitro and in vivo, whereas the folic acid analogue 2 did not exhibit any significant toxicity.

Nucleosides. 136. Synthesis and antiviral effects of several 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-alkyluracils. Some structure-activity relationships

In order to study structure-activity relationships between antiherpetic activity and the size of the C-5 alkyl substituents of 2'-fluoro-ara-U derivatives, six new nucleosides (1c-h) were synthesized. The 5-allyl analogue 1c was prepared by a Pd(II)-catalyzed reaction of 5-(chloromercuri)-1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)uracil with allyl chloride. Partial hydrogenation of 1c afforded the 5-n-propyl derivative 1d (FPAU). Nucleosides 1e-h were obtained by condensation of 3-O-acetyl-5-O-benzoyl-2-deoxy-2-fluoro-D-arabinosyl bromide with the corresponding 5-substituted uracils. Preliminary in vitro data show that, as the alkyl side chain is increased by one carbon unit, the antiherpetic potency is decreased by approximately 1 log order. The cytotoxicity also diminishes as the size of the 5-substituent is increased. FPAU exerts good activity against HSV-1 and HSV-2. FiPAU still shows good therapeutic indices, whereas the higher alkyl analogues are essentially inactive.

Nucleosides. 129. Synthesis of antiviral nucleosides: 5-alkenyl-1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)uracils

Synthesis of 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)uracils containing a vinyl (4a), 2-halovinyl (4b-d), or ethyl substituent at C-5 was achieved. These nucleosides were found to be about a log order less active than 2'-fluoro-5-iodo-ara-C (FIAC) against HSV-1, but they are much less cytotoxic against normal human lymphocytes than FIAC. Nucleosides 4a and 4e showed good activity against HSV-1 (ED50 = 0.16 and 0.24 microM, respectively) and HSV-2 (ED50 = 0.69 and 0.65 microM) with very little cytotoxicity (ID50 greater than 100 microM).

Activity of 1-(2'-fluoro-2'-deoxy-beta-D-arabinofuranosyl)thymine against herpes simplex virus in cell cultures and rabbit eyes

A new antiviral compound 1-(2'-fluoro-2'-deoxy-beta-D-arabinofuranosyl)thymine (2'-fluoro-5-methyl-ara-uracil [FMAU]), was compared with acyclovir and idoxuridine in vitro against two strains of both herpes simplex virus type 1 (HSV-1) and HSV-2. Determinations of the 50% effective dose varied slightly with each strain and with the host cells employed. The 50% effective dose for FMAU and acyclovir against HSV-1 ranged from 0.1 microM to 0.5 to 0.6 microM in rabbit kidney cells and from 0.5 microM to 0.6 to 0.78 microM in Vero cells. Beginning 4 days post-inoculation, topical FMAU therapy given five times per day to rabbits with acute herpetic keratitis either suppressed or delayed the severity of corneal epithelial involvement, conjunctivitis, iritis, and corneal clouding. Responses to treatment with FMAU were similar to those obtained with acyclovir and significantly better than those attained with idoxuridine and vidarabine. At 30 to 40 days after the end of treatment, rabbit eyes were subjected to iontophoresis with epinephrine in an attempt to induce reactivation and enhance detection of previously latent HSV-1. Latent HSV-1 was detected in 67 to 92% of trigeminal ganglia in FMAU-treated animals and in 90% of placebo-treated animals.

Nucleosides. 123. Synthesis of antiviral nucleosides: 5-substituted 1-(2-deoxy-2-halogeno-beta-D-arabinofuranosyl)cytosines and -uracils. Some structure-activity relationships

The syntheses of several 2'-halogeno-5-substituted-arabinofuranosylcytosines and -uracils are described, and relationships of structure to anti herpes virus activity in vitro were examined. Those arabinonucleosides containing the 2'-fluoro function exhibit, generally, more potent anti herpes virus (HSV) activity than do their 2'-chloro of 2'-bromo analogues. The importance of the fluorine in the 2'-"up" (arabino) configuration for enhancement of antiviral effectiveness is demonstrated by the superior activity of 2'-fluoro-5-iodo-ara-C [3a, FIAC] to that of 2'-fluoro-5-iodo-ribo-C. Of all the nucleosides tested herein, FIAC exhibited the most potent in vitro activity against HSV. 2'-Chloro-5-iodo- and -5-methyl-ara-C (3b and 4b) were 37 to greater than 500 times more effective in vitro against HSV type 2 than against type 1, suggesting that these latter derivatives might serve clinically as useful probes to distinguish between HSV types 1 and 2 in the diagnosis of HSV infections in man.

Quantitative autoradiographic mapping of herpes simplex virus encephalitis with a radiolabeled antiviral drug

2'-Fluoro-5-methyl-l-beta-D-arabinosyluracil (FMAU) labeled with carbon-14 was used to image herpes simplex virus type 1-infected regions of rat brain by quantitative autoradiography. FMAU is a potent antiviral pyrimidine nucleoside which is selectively phosphorylated by virus-coded thymidine kinase. When the labeled FMAU was administered 6 hours before the rats were killed, the selective uptake and concentration of the drug and its metabolites by infected cells (defined by immunoperoxidase staining of viral antigens) allowed quantitative definition and mapping of HSV-1-infected structures in autoradiograms of brain sections. These results show that quantitative autoradiography can be used to characterize the local metabolism of antiviral drugs by infected cells in vivo. They also suggest that the selective uptake of drugs that exploit viral thymidine kinase for their antiviral effect can, by appropriate labeling, be used in conjunction with clinical neuroimaging techniques to define infected regions of human brain, thereby providing a new approach to the diagnosis of herpes encephalitis in man.

Activity of 2-fluoro-5-methylarabinofuranosyluracil against mouse leukemias sensitive to and resistant to 1-beta-D-arabinofuranosylcytosine

A new pyrimidine nucleoside, 2'-fluoro-5-methyl-1-beta-D-arabinofuranosyluracil, previously has been shown to be active against the herpes group of viruses in vitro and in vivo. It is also active against mouse and human leukemic cells in culture and against mouse leukemias L1210, P388, and P815 in vivo. In contrast to other 1-beta-D-arabinofuranosylcytosine (ara-C) derivatives, 2'-fluoro-5-methyl-1-beta-D-arabinofuranosyluracil, when given either i.p. or p.o., is highly active against lines of leukemias P815 and L1210 made resistant to ara-C. Against P815/ara-C and L1210/araC, it is more effective than is 5-azacytidine, a drug which has shown definite effectiveness in patients with acute leukemia whose disease has become resistant to ara-C. For these reasons, 2'-fluoro-5-methyl-1-beta-D-arabinofuranosyluracil would seem to merit clinical trial in patients with acute nonlymphocytic leukemia whose disease has become resistant to ara-C.