Biomedical subjects

Alan Jackson

Publications and source records attributed to Alan Jackson.

At least 19 recordsLinked to original sources

PubMed2006

Host cytokine genotype is related to adverse prognosis and systemic inflammation in gastro-oesophageal cancer.

BACKGROUND: Systemic inflammation has been linked with reduced survival in cancer, however, the role of the host cytokine genotype versus tumour phenotype in the generation of this response is not clearly established. This study examined the relationship between cytokine polymorphisms (IL-1beta 511, IL-6 174, IL-10 1082, TNFalpha 308 and LTalpha +252) and serum cytokine concentrations, serum CRP concentration and survival duration in patients with gastro-oesophageal malignancy. METHODS: Two hundred and three newly diagnosed patients with gastric or oesophageal cancer had serum CRP and cytokine concentrations determined by ELISA. SNP genotyping was performed by Taqman allelic discrimination genotyping and compared with the genotype observed in 266 healthy volunteers. Clinico-pathological information was collected prospectively and survival duration was recorded. RESULTS: Distribution of the cytokine genotypes was similar between patients and controls. The IL-6 174 CC and IL-10 1082 GG genotypes were associated with elevated serum CRP (P = .03, P = .01, respectively; Mann-Whitney U test) and sTNF-R (P = .015, P = .02) concentrations. These genotypes were also associated with reduced survival duration (P = .01, P = .047; log-rank test). TNFalpha AA genotype was also associated with reduced survival duration on univariate (P = .032) and multivariate analysis (P = .006, multivariate model), but not with inflammatory markers. No other cytokine polymorphisms were associated with systemic inflammatory markers or prognosis. CONCLUSIONS: There is a pro-inflammatory cytokine haplotype (IL-6 CC, IL-10 GG, TNFalpha AA) that is associated with adverse prognosis that may act, at least in part, through an inflammatory mediated mechanism. Determining patients' cytokine haplotype may improve prognostication and allow stratification for intervention studies.

Adolescent↗

PubMed2006

Virchow-Robin space dilatation may predict resistance to antidepressant monotherapy in elderly patients with depression.

BACKGROUND: Late-life depressive disorders have been linked to cerebrovascular disease (the vascular depression hypothesis). Treatment resistance may be associated with vascular-based lesions in the white matter and basal ganglia. Virchow-Robin spaces (VRS) are cerebrospinal fluid spaces associated with microangiopathy of small cerebral vessels. This study tested the hypothesis that dilation of Virchow-Robin spaces seen on Magnetic Resonance Imaging (MRI) is associated with treatment resistance in elderly depressed individuals. METHODS: 50 patients with late-onset (age over 60 years) major depressive disorder (29 responders to monotherapy, 21 non-responders to monotherapy) and 35 normal volunteers were recruited. Assessment of deep white matter lesions [WML] and periventricular hyperintensities [PVH] (both with the Scheltens rating scale score, [Scheltens, P., Barkhof, F., Leys, D., et al. (1993) A semiquantative rating scale for the assessment of signal hyperintensities on magnetic resonance imaging. J Neurol Sci;114(1):7-12.]) and the severity of VRS dilatation (using a new scale) were scored from MRI images. Statistical group comparisons and multiple regression analyses were performed to quantify the relationship between imaging features and clinical outcome. RESULTS: There was a trend for greater WML Scheltens scores in the monotherapy resistant group compared to responders and control subjects, but only using the basal ganglia VRS score was there a statistically significant difference. A score of 2 or greater on the VRS score was 80% sensitive and 62% specific in predicting non-response to antidepressant monotherapy. The VRS score accounted for 38% of the variance in the multiple regression model and the PVH score, which was an independent predictor of outcome, contributed another 6%. LIMITATIONS: Numbers are small and type II errors possible, especially for the Scheltens ratings. Treatment response was limited to response or non-response to monotherapy and was retrospectively derived. The VRS scale was originally designed for use in patients with vascular dementia and has not been used before in affective disorders. Although all depressed subjects were late-onset, it is possible that depression led to vascular disease rather than vice versa. CONCLUSION: VRS dilatation is common in diseases associated with microvascular abnormality, which is the presumed basis of vascular depression in the elderly. VRS score may be useful in determining which patients are less likely to respond to antidepressant monotherapy. Prospective studies of patients with a wider range of treatment responses are indicated.

Aged↗

PubMed2006

Prognosis of late life depression: a three-year cohort study of outcome and potential predictors.

BACKGROUND: Late-onset depression (LOD) has a poor prognosis which may be worsened by the presence of cerebrovascular disease. Few studies have explored prospectively the influence of vascular risk factors on longer term prognosis. METHODS: The original study involved 50 patients with LOD and 35 healthy age matched controls. Follow-up was at three years. Baseline measures included clinical, neuroradiological and neuropsychological variables. Outcome was assessed by mortality, progression to dementia and clinical course of depressive disorder. RESULTS: Sixty-two (73%) of the original cohort agreed to be re-interviewed. Seven participants had died (all from the depressed group) and six developed dementia, all but one from the depressed group. Vascular dementia predominated (although not significantly so) among those with dementia at follow-up. For 28 depressed patients with complete follow-up data (56% of the original sample), poor outcome was predicted by lower High Density Lipoprotein (HDL), raised Erythrocyte Sedimentation Rate (ESR) and a higher score on the Hachinski Index scale and one test of immediate memory. Initial response to treatment was not associated with later outcome. CONCLUSION: Late-onset depressive disorder is associated with a high rate of mortality and possibly dementia. Biochemical and inflammatory markers may be important in prognosis and their role should be confirmed in future studies.

Age of Onset↗

PubMed2006

Comparative study into the robustness of compartmental modeling and model-free analysis in DCE-MRI studies.

PURPOSE: To evaluate and compare the reproducibility of the preferred phenomenological parameter IAUC60 (initial area under the time-concentration curve [IAUC] defined over the first 60 seconds postenhancement) with the preferred modeling parameter (K(trans)), as derived using two simple models, in abdominal and cerebral data collected in typical Phase I clinical trial conditions. MATERIALS AND METHODS: Dynamic contrast enhanced MRI (DCE-MRI) time series were acquired at two imaging centers from a group of patients with abdominal tumors and a group with gliomas. At both imaging centers, precontrast T1 was calculated using a variable flip angle three-dimensional spoiled gradient echo acquisition that was used to quantify tissue contrast agent concentration, allowing voxelwise definition of summary DCE-MRI parameters. RESULTS: A comparison of reproducibility showed that there was no statistically significant difference in reproducibility between IAUC60 and K(trans), although there was a trend towards better reproducibility for K(trans) (P = 0.0782). The 95% confidence intervals (CIs) for individual changes showed that for IAUC60 and K(trans), changes in excess of 47% and 31%, respectively, are outside the range of normal variability. CONCLUSION: Although modeling is more complex and more computationally intensive than an IAUC parameterization, our data suggest this approach to be preferable to a model-free approach since it provides greater physiological insight without a reduction in statistical power for Phase I/II clinical drug trials.

Abdominal Neoplasms↗

PubMed2006

Abnormalities of CSF flow patterns in the cerebral aqueduct in treatment-resistant late-life depression: a potential biomarker of microvascular angiopathy.

There is growing evidence that microvascular angiopathy (MVA) plays an important role in the development of dementia and affective disorders in older people. At currently available image resolutions it is not possible to image directly the vascular changes associated with MVA, but the effects on blood and cerebrospinal fluid (CSF) flow may be detectable. The aim of this study was to investigate a potential biomarker for MVA based on MRI of abnormalities in CSF flow. Since there is considerable indirect evidence that treatment resistance in late-onset depressive disorder is related to MVA, we assessed the method in a group of 22 normal volunteers and 29 patients with responsive (N=21) or treatment-resistant (N=8) late-onset depressive disorder. Single-slice quantified phase-contrast (PC) images of cerebral blood and CSF flow were collected at 15 points over a cardiac cycle, and the resulting flow curves were parameterized. Significant differences in the CSF flow (width of systolic flow peak and diastolic flow volume, both P<0.01) through the cerebral aqueduct were observed for the group of treatment-resistant patients when compared to age matched controls. No significant difference was observed for a group of 21 patients with treatment-responsive depression. The findings support the hypothesis that MR measurement of CSF flow abnormalities provides a biomarker of MVA, and thus could have application in a wide range of age-related diseases.

Aged↗

PubMed2006

Experimentally-derived functional form for a population-averaged high-temporal-resolution arterial input function for dynamic contrast-enhanced MRI.

Rapid T(1)-weighted 3D spoiled gradient-echo (GRE) data sets were acquired in the abdomen of 23 cancer patients during a total of 113 separate visits to allow dynamic contrast-enhanced MRI (DCE-MRI) analysis of tumor microvasculature. The arterial input function (AIF) was measured in each patient at each visit using an automated AIF extraction method following a standardized bolus administration of gadodiamide. The AIFs for each patient were combined to obtain a mean AIF that is representative for any individual. The functional form of this general AIF may be useful for studies in which AIF measurements are not possible. Improvements in the reproducibility of DCE-MRI model parameters (K(trans), v(e), and v(p)) were observed when this new, high-temporal-resolution population AIF was used, indicating the potential for increased sensitivity to therapy-induced change.

Abdominal Neoplasms↗

PubMed2006

Comparison of the performance of tracer kinetic model-driven registration for dynamic contrast enhanced MRI using different models of contrast enhancement.

RATIONALE AND OBJECTIVES: The quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) data is subject to model fitting errors caused by motion during the time-series data acquisition. However, the time-varying features that occur as a result of contrast enhancement can confound motion correction techniques based on conventional registration similarity measures. We have therefore developed a heuristic, locally controlled tracer kinetic model-driven registration procedure, in which the model accounts for contrast enhancement, and applied it to the registration of abdominal DCE-MRI data at high temporal resolution. MATERIALS AND METHODS: Using severely motion-corrupted data sets that had been excluded from analysis in a clinical trial of an antiangiogenic agent, we compared the results obtained when using different models to drive the tracer kinetic model-driven registration with those obtained when using a conventional registration against the time series mean image volume. RESULTS: Using tracer kinetic model-driven registration, it was possible to improve model fitting by reducing the sum of squared errors but the improvement was only realized when using a model that adequately described the features of the time series data. The registration against the time series mean significantly distorted the time series data, as did tracer kinetic model-driven registration using a simpler model of contrast enhancement. CONCLUSION: When an appropriate model is used, tracer kinetic model-driven registration influences motion-corrupted model fit parameter estimates and provides significant improvements in localization in three-dimensional parameter maps. This has positive implications for the use of quantitative DCE-MRI for example in clinical trials of antiangiogenic or antivascular agents.

Abdominal Neoplasms↗

PubMed2006

Losses in gross brain volume and cerebral blood flow account for age-related differences in speed but not in fluid intelligence.

Age-related gross head size; adjusted age-related change in brain volume and carotid and basilar blood flow; as well as scores on 3 tests of fluid intelligence (gf), 2 tests of information-processing speed, 2 memory tests, and 3 tests of executive function were obtained from 69 volunteers aged from 62 to 84 years. Brain volume negatively predicted scores on all 10 cognitive tasks, accounting for up to 78% of age-related variance in scores on the speed tasks and on 1 executive task. Cerebral blood flow (CBF) negatively predicted scores on 8 cognitive tasks, accounting for up to 36% of age-related variance in speed scores. However, neither brain volume nor CBF accounted for significant age-related variance between individuals on any of 3 gf tests. We conclude that speed, but not gf, is an exceptionally sensitive behavioral index of the progress of gross brain changes that affect cognition in old age and that speed and gf do not reflect integrity of the same functional systems.

Aged↗

PubMed2006

Deletion/insertion polymorphism of the angiotensin-converting enzyme gene and white matter hyperintensities in dementia: A pilot study.

OBJECTIVES: To examine the association between the angiotensin-converting enzyme (ACE) deletion/insertion (D/I) polymorphism and white matter hyperintensities (WMHs) in patients with dementia. DESIGN: Observational pilot study with adjustment for potential confounders using analysis of covariance. SETTING: Secondary care old-age psychiatry services in greater Manchester, United Kingdom. PARTICIPANTS: Ninety-seven patients with dementia: 49 with Alzheimer's disease (AD, National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association criteria) and 48 with vascular dementia (VaD, National Institute of Neurological Disorders and Stroke/Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria). MEASUREMENTS: The ACE D/I polymorphism, WMHs (deep WMHs (DWMHs) and periventricular hyperintensities (PVHs)) on T2-weighted magnetic resonance imaging, and potential cardiovascular confounders. RESULTS: The D/D polymorphism of the ACE genotype was associated with severity of DWMH (P = .005) but not PVH (P = .34), corrected for age, cardiovascular risk factors, and type of dementia. Post hoc analyses were limited by statistical power but suggested an interaction with the apolipoprotein E epsilon4 allele. CONCLUSION: The results support previous observations that genetic factors influence the development of WMHs in dementia. The involvement of the ACE D/I polymorphism in the pathogenesis of DWMHs in dementia (AD and VaD), by a mechanism that is independent of its association with cardiovascular risk factors, should be confirmed in a large population-based sample.

Aged↗

PubMed2005

Hormone replacement therapy and false positive recall in the Million Women Study: patterns of use, hormonal constituents and consistency of effect.

INTRODUCTION: Current and recent users of hormone replacement therapy (HRT) have an increased risk of being recalled to assessment at mammography without breast cancer being diagnosed ('false positive recall'), but there is limited information on the effects of different patterns of HRT use on this. The aim of this study is to investigate in detail the relationship between patterns of use of HRT and false positive recall. METHODS: A total of 87,967 postmenopausal women aged 50 to 64 years attending routine breast cancer screening at 10 UK National Health Service Breast Screening Units from 1996 to 1998 joined the Million Women Study by completing a questionnaire before screening and were followed for their screening outcome. RESULTS: Overall, 399 (0.5%) participants were diagnosed with breast cancer and 2,629 (3.0%) had false positive recall. Compared to never users of HRT, the adjusted relative risk (95% CI) of false positive recall was: 1.62 (1.43-1.83), 1.80 (1.62-2.01) and 0.76 (0.52-1.10) in current users of oestrogen-only HRT, oestrogen-progestagen HRT and tibolone, respectively (p (heterogeneity) < 0.0001); 1.65 (1.43-1.91), 1.49 (1.22-1.81) and 2.11 (1.45-3.07) for current HRT used orally, transdermally or via an implant, respectively (p (heterogeneity) = 0.2); and 1.84 (1.67-2.04) and 1.75 (1.49-2.06) for sequential and continuous oestrogen-progestagen HRT, respectively (p (heterogeneity) = 0.6). The relative risk of false positive recall among current users appeared to increase with increasing time since menopause, but did not vary significantly according to any other factors examined, including duration of use, hormonal constituents, dose, whether single- or two-view screening was used, or the woman's personal characteristics. CONCLUSION: Current use of oestrogen-only and oestrogen-progestagen HRT, but not tibolone, increases the risk of false positive recall at screening.

Breast Neoplasms↗

PubMed2005

Investigation into issues of passenger egress in Ladbroke Grove rail disaster.

This paper provides an overview of findings from the Health and Safety Laboratory investigation into human factors issues surrounding passenger escape and evacuation in the Ladbroke Grove train crash (1999). Drawing upon a range of contextual information the investigation focused upon identifying barriers and delays to evacuation following the incident. Findings highlight a number of important design shortcomings, as well as scope for the enhancement of both passive and active communication systems. The need to take account of passengers' mental models, intuitions and situation awareness when designing communication systems and emergency egress equipment for the railway carriage environment is highlighted.

Accidents↗

PubMed2005

Phase I investigation of recombinant anti-human vascular endothelial growth factor antibody in patients with advanced cancer.

We assessed the tolerability, safety, pharmacokinetics and dose-limiting toxicity (DLT) of the recombinant humanized IgG4 anti-vascular endothelial growth factor (VEGF) monoclonal antibody, HuMV833, in patients with advanced cancer. Cohorts of patients with progressive solid tumours received escalating doses of HuMV833 as a 1-h intravenous (I.V.) infusion on days 1, 15, 22, and 29. Twenty patients (median Eastern Cooperative Oncology Group (ECOG) score 1) were accrued. HuMV833 infusions were well tolerated and there were no grade III or IV toxicities definitely related to the antibody. Grade I or II toxicities probably related to the antibody included fatigue, dyspnoea and rash. There were two episodes of asymptomatic hypocalcaemia, one at grade III and one grade IV, which were recorded in early follow-up. There were eight grade I episodes of asymptomatic elevation of activated partial thromboplastin time (APTT) and two grade III events; one in a patient receiving 1 mg/kg and the other receiving extended doses of 10 mg/kg. Pharmacokinetic analysis revealed a non-linear kinetic and an elimination half-life of between 8.2 (0.3 mg/kg) and 18.7 (10 mg/kg) days. One patient with ovarian cancer experienced a partial response (PR) of 9 months duration and eight had disease stabilisation (SD) including one patient with colorectal carcinoma whose disease was stable for 14 months. In 13 of the 14 samples taken from 12 patients, the plasma concentration of hepatocyte growth factor (HGF) was reduced 24 h after drug administration. HuMV833 is safe and lacked DLT at doses up to 10 mg/kg on this schedule. Multiple doses were well tolerated, despite occasional asymptomatic elevations in APTT. By combining pharmacokinetic, pharmacodynamic and toxicity data, we can identify doses of 1 and 3mg/kg for further investigation. HuMV833 appears to possess some clinical activity.

Adult↗

PubMed2005

Improved quantitative dynamic regional oxygen-enhanced pulmonary imaging using image registration.

Oxygen-enhanced MR imaging has been demonstrated in a number of recent studies as a potential method to visualize regional ventilation in the lung. A quantitative pixel-by-pixel analysis is hampered by motion and volume change due to breathing. In this study, image registration via active shape modeling is shown to produce significant improvements in the regional analysis of both static and dynamic oxygen-enhanced pulmonary MRI for five normal volunteers. The method enables the calculation of regional change in relaxation rate between breathing air and 100% oxygen, which is proportional to the change in regional oxygen concentration, and regional oxygen wash-in and wash-out time constants. Registration-corrected mapping of these parameters is likely to provide improved information in the regional assessment of a range of lung diseases.

Administration, Inhalation↗

PubMed2005

Tracer kinetic model-driven registration for dynamic contrast enhanced MRI time series.

Motion during time-series data acquisition causes model-fitting errors in quantitative dynamic contrast-enhanced (DCE) MRI studies. Motion correction techniques using conventional registration cost functions may produce biased results because they were not designed to deal with the time-varying information content due to contrast enhancement. We present a locally-controlled, 3D translational registration process driven by tracer kinetic modeling that successfully registers abdominal DCE-MRI data at high temporal resolution and compare this method to a similar approach based on registration to the time series mean image in data from 8 patients. When the registration is driven by an appropriate model, we find significant improvements in model-fitting. Also, model-driven registration influences parameter estimates and reduces repeat study variability in measurements of blood volume.

Abdomen↗

PubMed2005

Size and growth rate of sporadic vestibular schwannoma: predictive value of information available at presentation.

BACKGROUND: The current study examines the hypothesis that tumor growth rate in sporadic vestibular schwannoma could be in part predicted by data available at diagnosis, such as tumor volume, patient age, laterality, and sex. METHODS: Tumor volumes and growth rates were calculated from serial magnetic resonance imaging data in a cohort of 50 patients (26 men and 24 women; mean age at presentation, 64.1 +/- 12.8 yr). Tumor volumes were measured using an algorithm that corrects for partial volume averaging errors and provides accurate estimates of tumor volume with known errors. RESULTS: Examination of presentation data showed no relationship between tumor size at diagnosis and patient age, sex, or tumor laterality. Two measurements of tumor growth--absolute growth per annum and tumor volume doubling time--were studied, and neither showed any relationship with tumor size at presentation, patient age, tumor laterality, or sex. CONCLUSION: The study represents a typical spectrum of patient ages and is of sufficient size in view of the distribution pattern of the variables to give a calculated statistical power in excess of 90% for each variable. This indicates that the clinical features available at presentation and diagnosis have no power to predict the expected behavior of sporadic vestibular schwannoma.

Adult↗

PubMed2005

Neurological findings in late-onset depressive disorder: comparison of individuals with and without depression.

BACKGROUND: Organic factors are thought to be important in late-life depressive disorder but there have been few studies specifically of neurological signs. AIMS: To compare neurological signs in a group of patients with late-onset depression and in healthy controls. METHOD: A case-control study comparing 50 patients with depression and 35 controls on three measures of central nervous system (CNS) signs: a structured CNS examination, the Neurological Evaluation Scale (NES) and the Webster rating scale for parkinsonism. RESULTS: After adjusting for major depression at the time of evaluation and prescription of tranquillisers, ratings on two of the NES sub-scales (complex motor sequencing and 'other' signs) and on the Webster scale were significantly higher (more impaired) in patients compared with controls (P<0.05). With logistic regression, the NES was the main measure predictive of group outcome. There were no differences in scores of vascular risk or white matter but patients had patients had more atrophy. CONCLUSIONS: The findings add to the evidence that late-life depression is associated with organic brain dysfunction, perhaps mediated by neurodegeneration or subtle vascular impairment. The use of the NES in subjects with depression should be replicated.

Age of Onset↗

PubMed2005

The hard side of change management.

Everyone agrees that managing change is tough, but few can agree on how to do it. Most experts are obsessed with "soft" issues, such as culture and motivation, but, say the authors, focusing on these issues alone won't bring about change. Companies also need to consider the hard factors-like the time it takes to complete a change initiative, the number of people required to execute it, and so forth. When the authors studied change initiatives at 225 companies, they found a consistent correlation between the outcomes of change programs (success versus failure) and four hard factors, which they called DICE: project duration, particularly the time between project reviews; integrity of performance, or the capabilities of project teams; the level of commitment of senior executives and staff; and the additional effort required of employees directly affected by the change. The DICE framework is a simple formula for calculating how well a company is implementing, or will be able to implement, its change initiatives. The framework comprises a set of simple questions that help executives score their projects on each of the four factors; the lower the score, the more likely the project will succeed. Companies can use DICE assessments to force conversations a bout projects, to gauge whether projects are on track or in trouble, and to manage project portfolios. The authors have used these four factors to predict the outcomes and guide the execution of more than 1,000 change management programs worldwide. Not only has the correlation held, but no other factors (or combination of factors) have predicted outcomes as successfully.

Commerce↗

PubMed2004

Characterization of cigarette smoke-induced inflammatory and mucus hypersecretory changes in rat lung and the role of CXCR2 ligands in mediating this effect.

Repetitive, acute inflammatory insults elicited by cigarette smoke (CS) contribute to the development of chronic obstructive pulmonary disease (COPD), a disorder associated with lung inflammation and mucus hypersecretion. Presently, there is a poor understanding of the acute inflammatory mechanisms involved in this process. The aims of this study were to develop an acute model to investigate temporal inflammatory changes occurring after CS exposure. Rats were exposed to whole body CS (once daily) generated from filtered research cigarettes. Initial studies indicated the generation of a neutrophilic/mucus hypersecreting lung phenotype in <4 days. Subsequent studies demonstrated that just two exposures to CS (15 h apart) elicited a robust inflammatory/mucus hypersecretory phenotype that was used to investigate mechanisms driving this response. Cytokine-induced neutrophil chemoattractants (CINCs) 1-3, the rat growth-related oncogene-alpha family homologs, and IL-1beta demonstrated time-dependent increases in lung tissue or lavage fluid over the 24-h period following CS exposure. The temporal changes in the neutrophil chemokines, CINCs 1-3, mirrored increases in neutrophil infiltration, indicative of a role in neutrophil migration. In addition, a specific CXCR2 antagonist, SB-332235, effectively inhibited CS-induced neutrophilia in a dose-dependent manner, supporting this conclusion. This modeling of the response of the rat airways to acute CS exposure indicates 1) as few as two exposures to CS will induce a phenotype with similarities to COPD and 2) a novel role for CINCs in the generation of this response. These observations represent a paradigm for the study of acute, repetitive lung insults that contribute to the development of chronic disease.

Animals↗