Biology subjects

Khan, A. F.

Publications and source records attributed to Khan, A. F..

3 recordsLinked to original sources

bioRxiv2025

Task-Based Spinal fMRI using a Median Nerve Stimulation Reveals Functional Alterations in Degenerative Cervical Myelopathy

Functional spinal cord MRI (fMRI) is an emerging technique for evaluating sensorimotor responses in both healthy and disease states. However, degenerative cervical myelopathy (DCM), a non-traumatic, age-related pathology characterized by spinal cord compression, often leads to motor and sensory impairments that make standard task-based fMRI paradigms challenging to perform or execute. To overcome this, we implemented an fMRI paradigm using direct electrical stimulation to the median nerve to evoke neural responses in both motor and sub-motor spinal cord pathways. In this study, 23 DCM and 23 aged-matched healthy controls (HC) underwent two task-based spinal cord fMRI sessions with direct, median nerve stimulation to the right upper limb. Motor thresholds were determined on an individual basis by a thumb/finger twitching, and sub-motor thresholds were set to be 15% underneath motor with no visible twitching. Blood Oxygenation Level Depended (BOLD) signals were analyzed across the C5-C8 cervical spinal cord segments. HCs demonstrated increased activation during motor vs sub-motor stimulation (1155 vs 496 voxels; +7.1%), whereas DCM patients showed reduction in activation with higher stimulation (1028 vs 1220 voxels; -2.2%). This activation pattern was consistent across the cervical spinal segments, with HCs peaking at C7 (sub-motor: 328 voxels, motor: 608 voxels), which is consistent with median nerve input for forearm and hand. While DCM responses were altered, with sub-motor differentially maximized at C6 (406 voxels) and abnormal recruitment at C5 (112 voxels) and C8 (198 voxels). Spatially, HC responses were focused in the gray matter (GM) and bilateral, whereas DCM responses showed reduced GM localization and were more ipsilateral. Furthermore, we saw spikes in sub-motor DCM deactivation at the overall (3032 voxels) and C6 root level (1500 voxels) that were greater than the other conditions. This study demonstrates the feasibility and effectiveness of median nerve stimulation as a task-based paradigm for assessing spinal cord function in those with spinal cord compression. Group level differences between DCM patients and age-matched HCs showed spatial and quantitatively distinct patterns across stimulation thresholds and spinal segments. Our findings suggest disrupted sub-motor and motor activation in the DCM group, highlighting the use of this approach as a functional biomarker to capture disease specific alterations.

neuroscience↗

bioRxiv2022

PKCβ facilitates leukemogenesis in chronic lymphocytic leukaemia by promoting constitutive BCR-mediated signaling

B cell antigen receptor (BCR) signaling competence is critical for pathogenesis of chronic lymphocytic leukemia (CLL). Defining key proteins that facilitate these networks aid in the identification of targets for therapeutic exploitation. We previously demonstrated that reduced PKC function in mouse hematopoietic stem/progenitor cells (HPSCs) resulted in PKC{beta}II upregulation and generation of a poor-prognostic CLL-like disease. Here, prkcb knockdown in HSPCs leads to reduced survival of PKC-KR-expressing CLL-like cells, concurrent with reduced expression of the leukemic markers CD5 and CD23. SP1 promotes elevated expression of prkcb in PKC-KR expressing cells enabling leukemogenesis. Global gene analysis revealed an upregulation of genes associated with B cell activation in PKC-KR expressing cells, coincident with upregulation of PKC{beta}II: supported by activation of key signaling hubs proximal to the BCR and elevated proliferation. Ibrutinib (BTK inhibitor) or enzastaurin (PKC{beta}II inhibitor) treatment of PKC-KR expressing cells and primary CLL cells showed similar patterns of Akt/mTOR pathway inhibition, supporting the role for PKC{beta}II in maintaining proliferative signals in our CLL mouse model. Ibrutinib or enzastaurin treatment also reduced PKC-KR-CLL cell migration towards CXCL12. Overall, we demonstrate that PKC{beta} expression facilitates leukemogenesis and identify that BCR-mediated signaling is a key driver of CLL development in the PKC-KR model. Statement of SignificancePKC{beta} facilitates leukemogenesis of CLL, driven through an SP1-regulated transcriptional program and promotes BCR signaling. Thus far, PKC{beta} is the only kinase within the BCR signaling pathway, a key pathway in driving CLL pathogenesis, implicated in the generation of neoplastic B lineage cells.

cancer biology↗

bioRxiv2019

Blood and Brain Gene Expression Trajectories Underlying Neuropathology and Cognitive Impairment in Neurodegeneration

Neurodegenerative disorders take decades to develop and their early detection is challenged by confounding non-pathological aging processes. For all neurodegenerative conditions, we lack longitudinal gene expression (GE) data covering their large temporal evolution, which hinders the fully understanding of the underlying dynamic molecular mechanisms. Here, we aimed to overcome this limitation by introducing a novel GE contrastive trajectory inference (GE-cTI) method that reveals enriched temporal patterns in a diseased population. Evaluated on 1969 subjects in the spectrum of late-onset Alzheimers and Huntingtons diseases (from ROSMAP, HBTRC and ADNI studies), this unsupervised machine learning algorithm strongly predicts neuropathological severity (e.g. Braak, Amyloid and Vonsattel stages). Furthermore, when applied to in-vivo blood samples (ADNI), it predicts 97% of the variance in memory deterioration and its future declining rate, supporting the identification of a powerful and minimally invasive (blood-based) tool for early clinical screening and disease prevention. This technique also allows the discovery of genes and molecular pathways, in both peripheral and brain tissues, that are highly predictive of disease evolution. Eighty percent of the most predictive molecular pathways identified in the brain were also top predictors in the blood. The GE-cTI is a promising tool for revealing complex neuropathological mechanisms, with direct implications for implementing personalized dynamic treatments in neurology. HIGHLIGHTS- Unsupervised learning detects enriched gene expression (GE) trajectories in disease - These plasma and brain GE trajectories predict neuropathology and future cognitive impairment - Most predictive molecular functions/pathways in the brain are also top predictors in the plasma - By identifying plasma GE trajectories, patients can be easily screened and follow dynamic treatments

neuroscience↗