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  • 1
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    Online Resource
    Small bowel water content assessed by MRI in health and disease: a collation of single‐centre studies
    Wiley ; 2022
    In:  Alimentary Pharmacology & Therapeutics Vol. 55, No. 3 ( 2022-02), p. 327-338
    Details
    In: Alimentary Pharmacology & Therapeutics, Wiley, Vol. 55, No. 3 ( 2022-02), p. 327-338
    Abstract: New developments in MRI have allowed the non‐invasive, accurate measurement of the small bowel water content (SBWC). Aims To collate studies measuring SBWC following ingestion of a range of foods in both health and disease to provide data for adequately powering future studies in this area. Methods This collation brings together 29 studies including 954 participants (530 healthy, 54 diverticulosis, 255 IBS, 53 functional constipation, 12 cystic fibrosis, 15 Crohn's disease, 20 coeliac disease, 15 scleroderma) which have been carried out in a single centre using comparable study designs. Results Fasting SBWC (mean 82 [SD 65] mL) shows high variability with a small decline with advancing age (healthy volunteers only; individual patient data). Fasting values are increased in untreated coeliac disease (202 [290]  mL, P  = 0.004). Post‐prandial SBWC shows less intra‐individual variability than fasting values in healthy volunteers. SBWC is increased by eating, most markedly by high fat meals but also by fibre, both viscous and particulate. Indigestible residue accumulates in late post‐prandial period but empties soon after ingestion of a high calorie meal which produces a significant drop (by 50 [52] mL) in healthy volunteers. The associated fall in SBWC is abnormal in people with cystic fibrosis (SBWC reduced by 10 [121]  mL, P  = 0.002) and in people with irritable bowel syndrome with diarrhoea (SBWC reduced by 17 [43] mL, P  = 0.007). Conclusions SBWC as assessed by MRI is a valuable biomarker indicating the balance of secretion and absorption in health and disease and the impact of treatments.
    Type of Medium: Online Resource
    ISSN: 0269-2813 , 1365-2036
    URL: Issue
    URL: Article
    DOI: 10.1111/apt.v55.3
    DOI: 10.1111/apt.16673
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2003094-0
    SSG: 15,3
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  • 2
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    Mechanisms underlying effects of kiwifruit on intestinal function shown by MRI in healthy volunteers
    Wiley ; 2019
    In:  Alimentary Pharmacology & Therapeutics Vol. 49, No. 6 ( 2019-03), p. 759-768
    Details
    In: Alimentary Pharmacology & Therapeutics, Wiley, Vol. 49, No. 6 ( 2019-03), p. 759-768
    Abstract: Chronic constipation affects approximately 17% of the population worldwide and remains an important unmet need since patients are often dissatisfied with treatment. Kiwifruit may offer an alternative to traditional laxatives and have been shown to increase stool volume, frequency and improve consistency. Aims Using non‐invasive MRI techniques, we assessed the effect of ingestion of kiwifruit on fluid distribution in the intestines and bowel function. Methods Two period crossover trial of kiwifruit vs control in healthy adults. Intervention: two kiwifruits twice daily vs isocaloric control (maltodextrin) twice daily, consumed for a total of 3 days. Subjects underwent MRI scanning fasted and at hourly intervals for 7 hours on the third day. Primary outcome: T1 relaxation time of ascending colon (T1AC) using MRI. Secondary outcomes: Small bowel water content (SBWC), colonic volume, gut transit time, T1 of descending colon, stool frequency and form. Results Fourteen volunteers completed the study. T1AC was higher after kiwifruit ingestion (P = 0.029) during the second half of the day (when meal residue would be expected to reach the AC, AUC T1 T240‐420 minutes; mean (SD) 137 (39) s*minute with kiwifruit versus 108 (40) s*minute with control. SBWC (P 〈 0.001), colon volumes (P = 0.004), as well as stool frequency (1.46 ± 0.66 with kiwifruit vs 1.14 ± 0.46 stools per day with control; P = 0.034) and stool form score (Bristol Stool Chart score 4.1 (0.9) with kiwifruit versus 3.4 (0.7) with control; P = 0.011) were markedly increased in participants consuming kiwifruit compared to control. Conclusion Consumption of kiwifruit in healthy volunteers increases water retention in the small bowel and ascending colon and increases total colonic volume. The data may explain the observed increase in stool frequency and looser stool consistencies, suggesting that kiwifruit could be used as a dietary alternative to laxatives in mild constipation.
    Type of Medium: Online Resource
    ISSN: 0269-2813 , 1365-2036
    URL: Issue
    URL: Article
    DOI: 10.1111/apt.2019.49.issue-6
    DOI: 10.1111/apt.15127
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2003094-0
    SSG: 15,3
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  • 3
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    Dimensions of manic symptoms in youth: psychosocial impairment and cognitive performance in the IMAGEN sample
    Wiley ; 2014
    In:  Journal of Child Psychology and Psychiatry Vol. 55, No. 12 ( 2014-12), p. 1380-1389
    Details
    In: Journal of Child Psychology and Psychiatry, Wiley, Vol. 55, No. 12 ( 2014-12), p. 1380-1389
    Abstract: It has been reported that mania may be associated with superior cognitive performance. In this study, we test the hypothesis that manic symptoms in youth separate along two correlated dimensions and that a symptom constellation of high energy and cheerfulness is associated with superior cognitive performance. Method We studied 1755 participants of the IMAGEN study, of average age 14.4 years ( SD  = 0.43), 50.7% girls. Manic symptoms were assessed using the Development and Wellbeing Assessment by interviewing parents and young people. Cognition was assessed using the Wechsler Intelligence Scale For Children ( WISC ‐ IV ) and a response inhibition task. Results Manic symptoms in youth formed two correlated dimensions: one termed exuberance , characterized by high energy and cheerfulness and one of undercontrol with distractibility, irritability and risk‐taking behavior. Only the undercontrol, but not the exuberant dimension, was independently associated with measures of psychosocial impairment. In multivariate regression models, the exuberant, but not the undercontrolled, dimension was positively and significantly associated with verbal IQ by both parent‐ and self‐report; conversely, the undercontrolled, but not the exuberant, dimension was associated with poor performance in a response inhibition task. Conclusions Our findings suggest that manic symptoms in youth may form dimensions with distinct correlates. The results are in keeping with previous findings about superior performance associated with mania. Further research is required to study etiological differences between these symptom dimensions and their implications for clinical practice.
    Type of Medium: Online Resource
    ISSN: 0021-9630 , 1469-7610
    URL: Issue
    URL: Article
    DOI: 10.1111/jcpp.2014.55.issue-12
    DOI: 10.1111/jcpp.12255
    RVK:
    XA 10000
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 1470297-6
    SSG: 5,2
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  • 4
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    Structural brain correlates of adolescent resilience
    Wiley ; 2016
    In:  Journal of Child Psychology and Psychiatry Vol. 57, No. 11 ( 2016-11), p. 1287-1296
    Details
    In: Journal of Child Psychology and Psychiatry, Wiley, Vol. 57, No. 11 ( 2016-11), p. 1287-1296
    Abstract: Read the Commentary on this article at doi: 10.1111/jcpp.12613
    Type of Medium: Online Resource
    ISSN: 0021-9630 , 1469-7610
    URL: Issue
    URL: Article
    DOI: 10.1111/jcpp.2016.57.issue-11
    DOI: 10.1111/jcpp.12552
    RVK:
    XA 10000
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 1470297-6
    SSG: 5,2
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  • 5
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    Separate neural systems for behavioral change and for emotional responses to failure during behavioral inhibition
    Wiley ; 2017
    In:  Human Brain Mapping Vol. 38, No. 7 ( 2017-07), p. 3527-3537
    Details
    In: Human Brain Mapping, Wiley, Vol. 38, No. 7 ( 2017-07), p. 3527-3537
    Abstract: To analyze the involvement of different brain regions in behavioral inhibition and impulsiveness, differences in activation were investigated in fMRI data from a response inhibition task, the stop‐signal task, in 1709 participants. First, areas activated more in stop‐success (SS) than stop‐failure (SF) included the lateral orbitofrontal cortex (OFC) extending into the inferior frontal gyrus (ventrolateral prefrontal cortex, BA 47/12), and the dorsolateral prefrontal cortex (DLPFC). Second, the anterior cingulate and anterior insula (AI) were activated more on failure trials, specifically in SF versus SS. The interaction between brain region and SS versus SF activations was significant ( P  = 5.6 * 10 −8 ). The results provide new evidence from this “big data” investigation consistent with the hypotheses that the lateral OFC is involved in the stop‐related processing that inhibits the action; that the DLPFC is involved in attentional processes that influence task performance; and that the AI and anterior cingulate are involved in emotional processes when failure occurs. The investigation thus emphasizes the role of the human lateral OFC BA 47/12 in changing behavior, and inhibiting behavior when necessary. A very similar area in BA47/12 is involved in changing behavior when an expected reward is not obtained, and has been shown to have high functional connectivity in depression. Hum Brain Mapp 38:3527–3537, 2017 . © 2017 Wiley Periodicals, Inc.
    Type of Medium: Online Resource
    ISSN: 1065-9471 , 1097-0193
    URL: Issue
    URL: Article
    DOI: 10.1002/hbm.v38.7
    DOI: 10.1002/hbm.23607
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 1492703-2
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  • 6
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    Cerebrovascular and blood–brain barrier impairments in Huntington's disease: Potential implications for its pathophysiology
    Wiley ; 2015
    In:  Annals of Neurology Vol. 78, No. 2 ( 2015-08), p. 160-177
    Details
    In: Annals of Neurology, Wiley, Vol. 78, No. 2 ( 2015-08), p. 160-177
    Abstract: Although the underlying cause of Huntington's disease (HD) is well established, the actual pathophysiological processes involved remain to be fully elucidated. In other proteinopathies such as Alzheimer's and Parkinson's diseases, there is evidence for impairments of the cerebral vasculature as well as the blood–brain barrier (BBB), which have been suggested to contribute to their pathophysiology. We investigated whether similar changes are also present in HD. Methods We used 3‐ and 7‐Tesla magnetic resonance imaging as well as postmortem tissue analyses to assess blood vessel impairments in HD patients. Our findings were further investigated in the R6/2 mouse model using in situ cerebral perfusion, histological analysis, Western blotting, as well as transmission and scanning electron microscopy. Results We found mutant huntingtin protein (mHtt) aggregates to be present in all major components of the neurovascular unit of both R6/2 mice and HD patients. This was accompanied by an increase in blood vessel density, a reduction in blood vessel diameter, as well as BBB leakage in the striatum of R6/2 mice, which correlated with a reduced expression of tight junction‐associated proteins and increased numbers of transcytotic vesicles, which occasionally contained mHtt aggregates. We confirmed the existence of similar vascular and BBB changes in HD patients. Interpretation Taken together, our results provide evidence for alterations in the cerebral vasculature in HD leading to BBB leakage, both in the R6/2 mouse model and in HD patients, a phenomenon that may, in turn, have important pathophysiological implications. Ann Neurol 2015;78:160–177
    Type of Medium: Online Resource
    ISSN: 0364-5134 , 1531-8249
    URL: Issue
    URL: Article
    DOI: 10.1002/ana.v78.2
    DOI: 10.1002/ana.24406
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 2037912-2
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  • 7
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    Fetal brain activity in response to a visual stimulus
    Wiley ; 2003
    In:  Human Brain Mapping Vol. 20, No. 4 ( 2003-12), p. 239-245
    Details
    In: Human Brain Mapping, Wiley, Vol. 20, No. 4 ( 2003-12), p. 239-245
    Type of Medium: Online Resource
    ISSN: 1065-9471 , 1097-0193
    URL: Issue
    URL: Journal
    URL: Article
    DOI: 10.1002/hbm.v20:4
    DOI: 10.1002/(ISSN)1097-0193
    DOI: 10.1002/hbm.10139
    Language: English
    Publisher: Wiley
    Publication Date: 2003
    detail.hit.zdb_id: 1492703-2
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  • 8
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    Coupling between cerebral blood flow and cerebral blood volume: Contributions of different vascular compartments
    Wiley ; 2019
    In:  NMR in Biomedicine Vol. 32, No. 3 ( 2019-03)
    Details
    In: NMR in Biomedicine, Wiley, Vol. 32, No. 3 ( 2019-03)
    Abstract: A better understanding of the coupling between changes in cerebral blood flow (CBF) and cerebral blood volume (CBV) is vital for furthering our understanding of the BOLD response. The aim of this study was to measure CBF‐CBV coupling in different vascular compartments during neural activation. Three haemodynamic parameters were measured during a visual stimulus. Look‐Locker flow‐sensitive alternating inversion recovery was used to measure changes in CBF and arterial CBV (CBV a ) using sequence parameters optimized for each contrast. Changes in total CBV (CBV tot ) were measured using a gadolinium‐based contrast agent technique. Haemodynamic changes were extracted from a region of interest based on voxels that were activated in the CBF experiments. The CBF‐CBV tot coupling constant α tot was measured as 0.16 ± 0.14 and the CBF‐CBV a coupling constant α a was measured as 0.65 ± 0.24. Using a two‐compartment model of the vasculature (arterial and venous), the change in venous CBV (CBV v ) was predicted for an assumed value of baseline arterial and venous blood volume. These results will enhance the accuracy and reliability of applications that rely on models of the BOLD response, such as calibrated BOLD.
    Type of Medium: Online Resource
    ISSN: 0952-3480 , 1099-1492
    URL: Issue
    URL: Article
    DOI: 10.1002/nbm.v32.3
    DOI: 10.1002/nbm.4061
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2002003-X
    detail.hit.zdb_id: 1000976-0
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  • 9
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    Measuring chemical exchange saturation transfer exchange rates in the human brain using a particle swarm optimisation algorithm
    Wiley ; 2023
    In:  NMR in Biomedicine
    Details
    In: NMR in Biomedicine, Wiley
    Abstract: The z‐spectrum contains many pools with different exchange rates and T 2 values, which can make it difficult to interpret in vivo data and complicates the design of experiments aimed at providing sensitivity to one pool. This work aims to characterise the main pools observable with MRI at 7T in the human brain. To achieve this, we acquired z‐spectra at multiple saturation powers in the human brain at 7T. We used simulations to optimise the use of particle swarm optimisation (PSO) to fit these data, validating this approach using further simulations and creatine phantoms. We then used the PSO to fit data from grey and white matter for the pool size, exchange rate, and T 2 of five proton pools (magnetisation transfer, amides, amines, nuclear Overhauser enhancement NOE −3.5ppm and NOE −1.7ppm in addition to water). We then devised an approach for using PSO to fit z‐spectra while limiting the computational burden, and we investigated the sensitivity of the fit to T 2 and k for three overlapping pools. We used this to measure the exchange rate of creatine and to show that it varied with temperature, as expected. In the brain we measured a significantly larger pool size in white matter than in grey matter for the magnetisation transfer pool and the NOE −3.5ppm pool. For all other parameters we found no significant difference between grey and white matter. We showed that PSO can be used to fit z‐spectra acquired at a range of B 1 to provide information about peak position, amplitude, exchange rate, and T 2 in vivo in the human brain. These data could provide more sensitivity to change in some clinical conditions and will also provide key information for further experimental design.
    Type of Medium: Online Resource
    ISSN: 0952-3480 , 1099-1492
    URL: Article
    DOI: 10.1002/nbm.5001
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 2002003-X
    detail.hit.zdb_id: 1000976-0
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  • 10
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    The impact of variations in subject geometry, respiration and coil repositioning on the specific absorption rate in parallel transmit abdominal imaging at 7 T
    Wiley ; 2023
    In:  NMR in Biomedicine
    Details
    In: NMR in Biomedicine, Wiley
    Abstract: Parallel transmit MRI at 7 T has increasingly been adopted in research projects and provides increased signal‐to‐noise ratios and novel contrasts. However, the interactions of fields in the body need to be carefully considered to ensure safe scanning. Recent advances in physically flexible body coils have allowed for high‐field abdominal imaging, but the effects of increased variability on energy deposition need further exploration. The aim of this study was to assess the impact of subject geometry, respiration phase and coil positioning on the specific absorption rate (SAR). Ten healthy subjects (body mass index [BMI] = 25 ± 5 kg m −2 ) were scanned (at 3 T) during exhale breath‐hold and images used to generate body models. Seven of these subjects were also scanned during inhale. Simplifications of the coil and body models were first explored, and then finite‐difference time‐domain simulations were run with a typical eight‐channel parallel transmit coil positioned over the abdomen. Simulations were used to generate 10 g averaged SAR (SAR 10g ) maps across 100,000 phase settings, and the worst‐case scenario 10 g averaged SAR (wocSAR 10g ) was identified using trigonometric maximisation. The average maximum SAR 10g across the 10 subjects with 1 W input power per channel was 1.77 W kg −1 . Hotspots were always close to the body surface near the muscle wall boundary. The wocSAR 10g across the 10 subjects ranged from 2.3 to 3.2 W kg −1 and was inversely correlated to fat volume percentage (R = 8) and BMI (R = 0.6). The coefficient of variation values in SAR 10g due to variations in subject geometry, respiration phase and realistic coil repositioning were 12%, 4% and 12%, respectively. This study found that the variability due to realistic coil repositioning was similar to the variability due to differing healthy subject geometries for abdominal imaging. This is important as it suggests that population‐based modelling is likely to be more useful than individual modelling in setting safe thresholds for abdominal imaging.
    Type of Medium: Online Resource
    ISSN: 0952-3480 , 1099-1492
    URL: Article
    DOI: 10.1002/nbm.5032
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 2002003-X
    detail.hit.zdb_id: 1000976-0
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