Browsing by Author "Fan, Jia"

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    Improving product release from saccharomyces cerevisiae and kluyveromyces lactis by pretreatment for cell wall weakening and selective product release
    (2009) Fan, Jia; Harrison, STL
    Efficient intracellular product release from yeast is required for the recovery of many bioproducts, recombinant or other. Traditionally such product release is achieved by non-selective, energy demanding mechanical disruption. The fine debris resulting from mechanical disruption is also challenging in the solid-liquid separation in downstream process. This study investigates the effect of the pretreatment on the energy efficiency of cell disruption, the extent of product release and its selective product release. Saccharomyces cerevisiae and Kluyveromyces lactis were used as the model microorganisms while disruption following pretreatment was achieved on exposure to ultrasound or passing through the high pressure homogenisation (HPH). Pretreatments were selected for their ability to weaken the yeast cell wall, rather than to permeabilise the cell. This allowed product release to be concentrated into the disruption step only, not distributed between the disruption and pretreatments steps. Rapid temperature treatment at 40 to 60CC, pH shock across the range pH 9 to 11 and osmotic pressure between 0.5 MPa and 5 MPa were used as single pretreatment. Combined pretreatments were also considered. These were affected by diluting the yeast suspension into a pre-warmed pH or high osmolarity buffer. On dilution, the temperature was increased rapidly to 40CC, while the pH or osmotic pressure was increased to pH 10 or 1 MPa.
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    Neuroimaging study of prenatal alcohol exposure effects on structural and functional connectivity in children
    (2015) Fan, Jia; Meintjes, Ernesta M; Taylor, Paul A
    Fetal alcohol spectrum disorders (FASD) describe the spectrum of cognitive, behavioural and neurological impairments associated with prenatal alcohol exposure (PAE). Diffusion tensor imaging (DTI) and resting-state functional MRI (rs-fMRI) were used to assess effects of PAE on microstructural integrities of cerebellar and cerebral white matters (WM) and on resting-state functional connectivity (RSFC) in gray matter (GM) in children with varying degrees of FASD severity (fetal alcohol syndrome (FAS) and partial FAS (PFAS)), as well as nonsyndromal heavily exposed (HE) children. Children with FAS revealed lower fractional anisotropy (FA) bilaterally in the superior peduncles. Mean diffusivity (MD) was higher in the left middle peduncle in children with FAS or PFAS (FAS/PFAS). Mediation of effects of PAE on eyeblink conditioning (EBC) provided statistical evidence that poorer microstructural integrity in these regions may play an important role in the EBC deficit observed in children with FASD. The FAS/PFAS children also revealed lower FA and/or higher MD in 7 cortical WM regions and lower RSFC in 5 GM regions within 5 networks. Four of the 7 WM and 3 of the 5 GM regions also showed alterations in HE children, providing evidence that alterations in nonsyndromal children are less extensive and that some regions appear to be relatively spared. Alterations in DTI parameters (FA and MD) were dose dependent in many, but not all, of the regions where group differences were detected, specifically in the left (L) and right (R) superior peduncles, L middle peduncle, L inferior longitudinal fasciculus, medial (M) splenium of the corpus callosum (CC), and M isthmus of the CC. The WM deficits were attributable to increased radial diffusivity (RD) rather than decreased axial diffusivity (AD), suggesting poorer axon packing density and/or myelination. Increasing alcohol exposure was associated with reduced fractional amplitude of low frequency fluctuations (fALFF), indicating changes in functional connectivity in the default mode, salience, and dorsal attention networks. The locations of the WM alterations found with DTI suggest that the compromised RSFC found in 3 of the 5 networks could be attributable to WM deficits in tracts providing intra-network connections.
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    Potential benefits and neural correlates of acupuncture treatment with or without physiotherapy on resting state functional connectivity in ischemic stroke patients with unilateral limb dysfunction
    (2024) Fouch, Sone; Fan, Jia; Meintjes Ernesta
    Introduction: Stroke patients often have lasting physical and cognitive impairments, leading to functional dependence even after discharge from hospital. Acupuncture has been recommended by the World Health Organisation (WHO) as an adjunctive treatment for stroke. Physiotherapy serves as the primary rehabilitation approach in South Africa and numerous other Western nations. Despite their widespread use, the precise mechanisms underlying both acupuncture and physiotherapy remain elusive, and the neurological alterations following extended rehabilitation programs are yet to be defined. Resting-state functional magnetic resonance imaging (rs-fMRI) is a non-invasive technique used to map brain regions that are temporally correlated, indicative of functional connectivity, during periods of rest. In the present study, treatment-related alterations in brain RSFC in ischaemic stroke patients with unilateral limb dysfunction were randomised to receive either 1) True Acupuncture (TA), 2) TA and Physiotherapy (PT), or 3) PT and Sham Acupuncture (SA), representing a placebo or nonacupoint acupuncture. Methods: Right-handed participants were recruited from the First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, including 23 stroke patients (58.5±8.0 yrs.) and 10 healthy controls (53.9±6.9 yrs.). As part of a stroke rehabilitation programme, stroke patients were assigned to one of the three treatment arms: TA alone (6 participants), TA with PT (7 participants), or SA with PT (10 participants). Each participants received 5 sessions over 3 weeks. Fugl-Meyer Assessment (FMA) data were collected before, after, and during (on day 8) treatment. MRI scans were performed on a 3T Skyra Scanner (Siemens, Erlangen, Germany) before and after the 3-week rehabilitation programme, including rs-fMRI using a gradient echo EPI sequence and T1-weighted structural images using an MPRAGE sequence. Healthy controls underwent a single scan without treatment. Rs-fMRI data were pre-processed using AFNI_proc.py. Eleven resting-state networks (RSNs) were identified through group independent component analysis (ICA) using FSL-MELODIC in data from the healthy controls. Dual regression and randomise in FSL were then applied to identify the clusters within the identified resting state networks (RSNs) showing significant differences (at p<0.01; cluster size threshold at α<0.05). The mean Z-score within each cluster was subsequently correlated to the FMA scores. Results: Before treatment, lower RSFC in 2 clusters in the precuneus within the Default Mode Network (DMN) and the Ventral Attention Network were found in the TA with PT group compared to the TA only and SA with PT groups. No significant differences in mean Z-scores within these two clusters were seen among the three groups after treatment. After treatment, differences in RSFC among groups were found in five regions within three networks, including the cingulate gyrus and the precuneus in the DMN, the orbitofrontal cortex in the executive control network, and the inferior and superolateral occipital lobe in the visual network. In all five of these regions, patients receiving TA+PT showed a significantly higher RSFC compared to individuals in the other groups. There were no significant differences in RSFC between groups in these five regions before treatment. After receiving TA+PT treatment, patients demonstrated higher resting-state functional connectivity (RSFC) compared to themselves before treatment in nine regions spanning four resting-state networks (RSNs), including the bilateral precuneus, right (R) anterior calcarine sulcus, R primary motor cortex, and left (L) angular gyrus in the first DMN; the bilateral precuneus in the second DMN; the R visual cortex, R posterior lingual gyrus and L visual cortex in the visual network; and the R posterior cingulate sulcus in the ventral attention network. However, after SA+PT treatment, individuals in the group exhibited lower RSFC compared to themselves before treatment in two regions within two networks, including the R postcentral gyrus in the somatosensory network and the L lingual gyrus in the visual network. All three treatment groups showed a significant increase in FMA scores from before treatment, to after treatment. No significant differences were found when comparing FMA scores between treatment groups. The TA+PT group's results showed a significant positive correlation between RSFC and FMA scores. Conclusions: Stroke patients who received one of three treatments demonstrated improved FMA scores, with no significant differences in FMA scores observed among the three treatment arms after treatment. Patients in the TA+PT group showed significant changes in key brain regions associated with cognition, sensorimotor integration, and motor function. Specifically, increases in RSFC within the precuneus, motor cortex, and posterior cingulate sulcus, which are involved in neural recovery and cognitive improvement. In contrast, the SA+PT group exhibited RSFC decreases within somatosensory and visual networks, indicating a different pattern of neural recognition. After treatment, patients in the TA+PT group exhibited higher RSFC in the precuneus in the DMN and executive control network. These findings highlight the potential efficacy of combining TA with PT for stroke rehabilitation, suggesting that this approach may facilitate positive neural adaptations. However, the study also highlights the necessity for further investigation with larger sample sizes and extended treatment durations to comprehensively grasp the efficacy and underlying mechanisms of this integrated approach