Biology subjects

Bhuiyan, R.

Publications and source records attributed to Bhuiyan, R..

3 recordsLinked to original sources

bioRxiv2025

High-Capacity transcranial Direct Current Stimulation (HC-tDCS)

BackgroundEnhancing tDCS technology can support the delivery of higher current intensities, enabling broader dose-response studies in human trials. MethodsHigh-Capacity tDCS (HC-tDCS) integrates novel electrodes and adaptive current/voltage controlled electronics. Multi-layer HC electrodes include polarity-specific redox layers and designed hydrogel interfaces, shaped for a bifrontotemporal montage. The stimulator design includes adaptive ramps with hybrid voltage-current control and low (7.5 V) compliance voltage. Scanning electron microscopy (SEM) and electrical impedance spectroscopy (EIS) were used to characterize electrode properties. Tolerability of HD-tDCS was tested for target currents 1-6 mA (in 1 mA increments) for 30 min on 5 healthy subjects, and compared with conventional tDCS using 2 mA F3-F4 sponge-electrodes. MRI-derived computational models predicted cortical electric fields. Tolerability was assessed according to the 100 mm visual analogue scale for pain (VASP-100), skin erythema assessment, thermal imaging, and adverse event questionnaires. ResultsThe electrode design including high-roughness polarity-specific capacity, electrochemically supports high-charge direct current stimulation. In all subjects, HC-tDCS was well tolerated at all tested doses (1-6 mA) with minor transient adverse events and average VASP-100 less than 15. VASP-100 during sponge-electrode tDCS at 2 mA was comparable to 5 and 6 mA HC-tDCS. HC-tDCS operates at significantly lower voltage than sponge-tDCS, impacting tolerability and efficiency. Modeling predicts peak frontal electric fields of 0.65-1.08 V/m for 2 mA HC-tDCS and 1.95-3.25 V/m for 6 mA HC-tDCS, compared to 0.49-0.95 V/m for 2 mA sponge-tDCS. ConclusionsHC-tDCS allows increased cortical stimulation; at 6 mA achieving double the 1 V/m electric field threshold in all subjects. Enabled by pre-stimulation procedures, specialized electrodes, and adaptive low-voltage stimulators, HC-tDCS is well tolerated at intensities up to at least 6 mA.

bioengineering↗

bioRxiv2025

Single-cell decoding of human islet cell type-specific alterations in type 2 diabetes reveals converging genetic- and state-driven β-cell gene expression defects

Pancreatic islets maintain glucose homeostasis through coordinated action of their constituent endocrine and affiliate cell types and are central to type 2 diabetes (T2D) genetics and pathophysiology. Our understanding of robust human islet cell type-specific alterations in T2D remains limited. Here, we report comprehensive single cell transcriptome profiling of 245,878 human islet cells from a 48-donor cohort spanning non-diabetic (ND), pre-diabetic (PD), and T2D states, identifying 14 distinct cell types detected in every donor from each glycemic state. Cohort analysis reveals [~]25-30% loss of functional beta cell mass in T2D vs. ND or PD donors resulting from (1) reduced total beta cell numbers/proportions and (2) reciprocal loss of high function and gain of senescent {beta}-cell subpopulations. We identify in T2D {beta}-cells 511 differentially expressed genes (DEGs), including new (66.5%) and validated genes (e.g., FXYD2, SLC2A2, SYT1), and significant neuronal transmission and vitamin A metabolism pathway alterations. Importantly, we demonstrate newly identified DEG roles in human {beta}-cell viability and/or insulin secretion and link 47 DEGs to diabetes-relevant phenotypes in knockout mice, implicating them as potential causal islet dysfunction genes. Additionally, we nominate as candidate T2D causal genes and therapeutic targets 27 DEGs for which T2D genetic risk variants (GWAS SNPs) and pathophysiology (T2D vs. ND) exert concordant expression effects. We provide this freely accessible atlas for data exploration, analysis, and hypothesis testing. Together, this study provides new genomic resources for and insights into T2D pathophysiology and human islet dysfunction.

genomics↗

bioRxiv2023

Wearable Disposable Electrotherapy

We design and validate a novel electrotherapy platform without electronic components, using printed abundant, environmentally benign materials. Whereas existing electrotherapy devices use an independent power source and electronics to generate and control stimulation currents, our design eliminates the need for these components. Device production relies only on scalable additive manufacturing and common materials, minimizing cost and environmental impact. The disposable single-use platform (as discreet as adhesive bandages) is activated simply by placement on the body. A prescribed electrotherapy discharge is regulated by a flexible 3D electrochemical architecture tailored to each application by a novel operational theory. The single-dose usability of this platform is a categorical shift from existing approaches with durable equipment that require programming and assembly to disposable electrodes for each use. Our Wearable Disposable Electrotherapy technology can be distributed like pharmacotherapy, with indications spanning neuromodulation of brain disorders, wound healing, transcutaneous drug delivery, bioelectronic medicine, and aesthetics.

bioengineering↗