Oscillometric blood pressure measurements on smartphones using vibrometric force estimation.

This paper proposes a smartphone-based method for measuring Blood Pressure (BP) using the oscillometric method. For oscillometry, it is necessary to measure (1) the pressure applied to the artery and (2) the local blood volume change. This is accomplished by performing an oscillometric measurement at the finger's digital artery, whereby a user presses down on the phone's camera with steadily increasing force. The camera is used to capture the blood volume change using photoplethysmography. We devised a novel method for measuring the force applied of the finger without the use of specialized smartphone hardware with a technique called Vibrometric Force Estimation (VFE). The fundamental concept of VFE relies on a phenomenon where a vibrating object is dampened when an external force is applied on to it. This phenomenon can be recreated using the phone's own vibration motor and measured using the phone's Inertial Measurement Unit (IMU). A cross device reliability study with three smartphones of different manufacturers, shape, and prices results in similar force estimation performance across all smartphone models. In an N = 24 proof of concept study of the BP measurement, the smartphone technique achieves a mean absolute error of 9.21 mmHg and 7.77 mmHg of systolic and diastolic BP, respectively, compared to an FDA approved BP cuff. The vision for this technology is not necessarily to replace existing BP monitoring solutions, but rather to introduce a downloadable smartphone software application that could serve as a low-barrier hypertension screening measurement fit for widespread adoption.

Sec23IP recruits VPS13B/COH1 to ER exit site-Golgi interface for tubular ERGIC formation.

VPS13B/COH1 is the only known causative factor for Cohen syndrome, an early-onset autosomal recessive developmental disorder with intellectual inability, developmental delay, joint hypermobility, myopia, and facial dysmorphism as common features, but the molecular basis of VPS13B/COH1 in pathogenesis remains largely unclear. Here, we identify Sec23 interacting protein (Sec23IP) at the ER exit site (ERES) as a VPS13B adaptor that recruits VPS13B to ERES-Golgi interfaces. VPS13B interacts directly with Sec23IP via the VPS13 adaptor binding domain (VAB), and the interaction promotes the association between ERES and the Golgi. Disease-associated missense mutations of VPS13B-VAB impair the interaction with Sec23IP. Knockout of VPS13B or Sec23IP blocks the formation of tubular ERGIC, an unconventional cargo carrier that expedites ER-to-Golgi transport. In addition, depletion of VPS13B or Sec23IP delays ER export of procollagen, suggesting a link between procollagen secretion and joint laxity in patients with Cohen disease. Together, our study reveals a crucial role of VPS13B-Sec23IP interaction at the ERES-Golgi interface in the pathogenesis of Cohen syndrome.

Simultaneous Estimation of Digit Tip Forces and Hand Postures in a Simulated Real-Life Condition With High-Density Electromyography and Deep Learning.

In myoelectric control, continuous estimation of multiple degrees of freedom has an important role. Most studies have focused on estimating discrete postures or forces of the human hand but for a practical prosthetic system, both should be considered. In daily life activities, hand postures vary for grasping different objects and the amount of force exerted on each fingertip depends on the shape and weight of the object. This study aims to investigate the feasibility of continuous estimation of multiple degrees of freedom. We proposed a reach and grasp framework to study both absolute fingertip forces and hand movement types using deep learning techniques applied to high-density surface electromyography (HD-sEMG). Four daily life grasp types were examined and absolute fingertip forces were simultaneously estimated while grasping various objects, along with the grasp types. We showed that combining a 3-dimensional Convolutional Neural Network (3DCNN) with a Long Short-term Memory (LSTM) can reliably and continuously estimate the digit tip forces and classify different hand postures in human individuals. The mean absolute error (MAE) and Pearson correlation coefficient (PCC) results of the force estimation problem across all fingers and subjects were 0.46 ± 0.23 and 0.90 ± 0.03% respectively and for the classification problem, they were 0.04 ± 0.01 and 0.97 ± 0.02%. The results demonstrated that both absolute digit tip forces and hand postures can be successfully estimated through deep learning and HD-sEMG.

Identification of Spared and Proportionally Controllable Hand Motor Dimensions in Motor Complete Spinal Cord Injuries Using Latent Manifold Analysis.

The loss of bilateral hand function is a debilitating challenge for millions of individuals that suffered a motor-complete spinal cord injury (SCI). We have recently demonstrated in eight tetraplegic individuals the presence of highly functional spared spinal motor neurons in the extrinsic muscles of the hand that are still capable of generating proportional flexion and extension signals. In this work, we hypothesized that an artificial intelligence (AI) system could automatically learn the spared electromyographic (EMG) patterns that encode the attempted movements of the paralyzed digits. We constrained the AI to continuously output the attempted movements in the form of a digital hand so that this signal could be used to control any assistive system (e.g. exoskeletons, electrical stimulation). We trained a convolutional neural network using data from 13 uninjured (control) participants and 8 tetraplegic participants (7 motor-complete, 1 incomplete) to study the latent space learned by the AI. Our model can automatically differentiate between eight different hand movements, including individual finger flexions, grasps, and pinches, achieving a mean accuracy of 98.3% within the SCI group. Analysis of the latent space of the model revealed that proportionally controllable movements exhibited an elliptical path, while movements lacking proportional control followed a chaotic trajectory. We found that proportional control of a movement can only be correctly estimated if the latent space embedding of the movement follows an elliptical path (correlation =0.73; p <0.001). These findings emphasize the reliability of the proposed system for closed-loop applications that require an accurate estimate of spinal cord motor output.

Results of innervated digital artery perforator flap and direct-flow homodigital flap application in fingertip soft tissue amputations.

OBJECTIVE: The purpose of this study is to compare the results of the innervated digital artery perforator (IDAP) flap and the direct-flow homodigital flap as reconstruction methods for fingertip soft tissue amputations. This issue is important in hand surgery, and we aim to identify the method that provides the best functional and cosmetic outcomes. METHODS: Between 2020 and 2022, 32 patients with fingertip amputations were reconstructed by the same surgeon using two different methods. The patients were retrospectively divided into two groups: those who underwent IDAP (n = 14) and those who had a direct-flow homodigital flap (n = 18). We compared the groups in terms of defect size, cold intolerance, venous congestion, Sollerman hand function test scores, Seddon sensory test scores, and follow-up periods, as well as flap viability, flexion contracture, and static two-point discrimination (s2PD). RESULTS: Of the 32 patients (26 men, 6 females; age: mean 28.72 ± 11.5 years), the injuries were caused by different mechanisms, including sharp (57.1% IDAP), crush (75% IDAP) and entanglement (66.7% homodigital). The average area of tissue loss was approximately 2.70 ± 1.37 cm², while the average s2PD measurement was approximately 4.94 ± 1.04 mm. Postoperatively, the Seddon sensory test results for the homodigital flap group were S4 (61.5%), S3 (23.1%), S3+ (7.7%), and S2 (7.7%), compared to the IDAP group, which showed S4 (57.9%), S3+ (21.1%), and S3 (21.1%). Complications occurred in five patients, though no flap loss or revision was required. The postoperative mean Sollerman hand function scores were higher for the homodigital group than for the IDAP group, with values of 75 ± 2.64 and 73 ± 3.34, respectively. Although not statistically significant, the results numerically suggest that the IDAP flap is better in terms of sensory recovery and hand function compared to the homodigital flap (p > 0.05). CONCLUSIONS: This is the first investigation to compare direct-flow flaps with IDAP. The average follow-up period for patients who underwent homodigital surgery was also shorter than that of the IDAP group. Furthermore, the mean postoperative two-point discrimination and postoperative Sollerman function score were higher in patients who had homodigital surgery.

Effect of Knife Use and Overlapping Gloves on Finger Temperature of Poultry Slaughterhouse Workers.

Brazilian poultry slaughterhouses employ many workers, consequently exposing them to various ergonomic risks. This study aimed to analyze the effects of knife use and overlapping gloves on the finger temperatures of poultry slaughterhouse workers. Employees (n = 571) from seven Brazilian poultry slaughterhouses participated in this cross-sectional study. A Flir® T450SC infrared camera was used to record thermographic images of the workers' hands. The workers were interviewed about work organization, cold thermal sensations, and the perception of upper-limb musculoskeletal discomfort. Dependent and independent sample t-tests and binary logistic regression models were applied. The results proved that the workers wore up to five overlapping gloves and had at least one finger with temperatures of ≤15 °C (46.6%) or ≤24 °C (98.1%). Workers that used a knife and wore a chainmail (CM) glove on their non-dominant hand had average finger temperatures significantly colder on the palmar surface than the anti-cut (AC) glove group (p = 0.029). The chance of one worker who wore a CM glove to have finger temperatures of ≤15 °C was 2.26 times greater than a worker who wore an AC glove. Those who wore an AC glove and those wearing a CM glove presented average overall finger temperatures significantly lower on the non-dominant hand (products) than the dominant hand (knife) (p < 0.001).

Cost and benefit of parafoveal information during reading acquisition as revealed by finger movement patterns.

Contrary to expert readers, children learning to read have limited ability to preprocess letters in parafoveal vision. Parafoveal letters induce crowding cost: the features of neighboring letters interfere with target letter identification. We longitudinally studied the weight of parafoveal cost and benefit in two group of children (N = 42), during their first school year (Group 1) and at the end of second school year (Groupe 2). Using a novel digit-tracking method, a blurred text was presented and rendered unblurred by touching the screen, allowing the user to discover a window of visible text as the finger moved along it. We compared two conditions: (1) a large window, where crowding was enhanced by the presence of parafoveal information; (2) a small window, where crowding was suppressed by blurred parafoveal information. Finger kinematics were simultaneously recorded. We found that at the beginning of first-grade, digital fixations - brief slowing or stopping of the finger on a specific point - are significantly longer in the large compared to the small window condition, as parafoveal crowding increases text processing difficulty. This effect diminishes and disappears at the end of second-grade as reading performance improves. In the large window condition, longer digital saccades - rapid movements of the finger changing position - appear by the end of first grade suggesting that parafoveal exposure become more beneficial than harmful when children acquire basic reading skills. Our results show that in beginning readers, crowding has a cognitive cost that interfere with the speed of the learning reading process. Our findings are relevant to the field of education by showing that visual crowding in first grade should not be underestimated.

Acromesomelic Dysplasia With Homozygosity for a Likely Pathogenic BMPR1B Variant: Postaxial Polydactyly as a Novel Clinical Finding.

BACKGROUND: Acromesomelic chondrodysplasias are a rare subgroup of the clinically and genetically heterogeneous osteochondrodysplasias that are characterised by abnormalities in the limb development and short stature. Here, we report a 2-year-old boy, offspring of consanguineous parents, with acromesomelic dysplasia and postaxial polydactyly in which exome sequencing identified a novel homozygous missense variant in BMPR1B. The patient showed skeletal malformation of both hands and feet that included complex brachydactyly with the thumbs most severely affected, postaxial polydactyly of both hands, shortened toes as well as a bilateral hypoplasia of the fibula. METHODS: Whole trio exome sequencing was conducted to identify potential genetic variants in the patient. RESULTS: The analysis identified the biallelic variant NM_001203.3:c.821A > G;p.(Gln274Arg) in BMPR1B, a gene encoding bone morphogenetic protein receptor 1B. CONCLUSION: The skeletal phenotype can be brought in line with the phenotypes of previously reported cases of BMPR1B-associated chondrodysplasias. However, the postaxial polydactyly described here is a novel clinical finding in a BMPR1B-related case; notably, it has previously been reported in other acromesomelic dysplasia cases caused by homozygous pathogenic variants in GDF5-a gene which encodes for growth differentiation factor 5, a high-affinity ligand to BMPR1B.

Anatomical research and clinical application of multistage advancement in dorsal finger V-Y flap.

OBJECTIVE: To investigate the anatomical basis and clinical efficiency of the advancement distance in dorsal digital V-Y advancement flap. MATERIALS AND METHODS: Thirty-four fingers in 11 fresh adult hand specimen were selected, V-Y flap was performed with the digital artery as vascular pedicle, and the advancement distance was measured. The relationship between the distance and extensibility of skin, sliding degree of subcutaneous superficial fascia, angular displacement of digital arterial dorsal branch, elasticity of digital artery was discussed. Two cases were provided to demonstrate the feasibility and importance of this flap. RESULTS: In the dorsal digital V-Y advancement flap simulated on fresh adult hand specimens, the mean advance distance of the middle segment flap and proximal segment flap is 18 ± 0.8 mm and 34 ± 1.7 mm, respectively, and the maximum can reach 24 and 45 mm, respectively. Two cases of dorsal digital V-Y advancement flaps were designed and performed in the dorsal side of the ring finger middle segment and the thumb proximal segment, respectively. The advancement distances were 25 and 26 mm, respectively. All flaps survived completely and the incisions healed by first intention. The flap texture was good, the affected finger was symmetrical, and the activity and sensation restored well. CONCLUSION: The dorsal digital V-Y advancement flap with the digital artery as the main vascular pedicle can exert four factors for advancement effect, and significantly increase the advancement distance. The operation is simple, the blood supply is reliable, and the postoperative sensation is normal. It is an ideal flap for repairing the digital dorsal defect.

Loss of PHF6 causes spontaneous seizures, enlarged brain ventricles and altered transcription in the cortex of a mouse model of the Börjeson-Forssman-Lehmann intellectual disability syndrome.

Börjeson-Forssman-Lehmann syndrome (BFLS) is an X-linked intellectual disability and endocrine disorder caused by pathogenic variants of plant homeodomain finger gene 6 (PHF6). An understanding of the role of PHF6 in vivo in the development of the mammalian nervous system is required to advance our knowledge of how PHF6 mutations cause BFLS. Here, we show that PHF6 protein levels are greatly reduced in cells derived from a subset of patients with BFLS. We report the phenotypic, anatomical, cellular and molecular characterization of the brain in males and females in two mouse models of BFLS, namely loss of Phf6 in the germline and nervous system-specific deletion of Phf6. We show that loss of PHF6 resulted in spontaneous seizures occurring via a neural intrinsic mechanism. Histological and morphological analysis revealed a significant enlargement of the lateral ventricles in adult Phf6-deficient mice, while other brain structures and cortical lamination were normal. Phf6 deficient neural precursor cells showed a reduced capacity for self-renewal and increased differentiation into neurons. Phf6 deficient cortical neurons commenced spontaneous neuronal activity prematurely suggesting precocious neuronal maturation. We show that loss of PHF6 in the foetal cortex and isolated cortical neurons predominantly caused upregulation of genes, including Reln, Nr4a2, Slc12a5, Phip and ZIC family transcription factor genes, involved in neural development and function, providing insight into the molecular effects of loss of PHF6 in the developing brain.

Enhancing smartphone security with human centric bimodal fallback authentication leveraging sensors.

Smartphones store valuable personal information, necessitating robust authentication methods to protect user data. This research proposes a lightweight bi-model fallback authentication technique that combines dynamic security questions and finger pattern recognition using inertial measurement units. The dynamic security questions are generated based on the smartphone's usage behavior, while the owner's finger movements are captured using four different inertial sensors: accelerometer, gyroscope, gravity sensor, and magnetometer. By combining the answers to the questions and the owner's finger movements, the user can be authenticated even if the primary authentication method fails. In this study, data was collected from 24 participants, including 12 primary phone users and 12 close adversaries, over a span of 28 days. The dynamic security questions, derived from call, SMS, battery charging events, application usage, location, and physical activity categories, achieved high accuracy rates, with call, SMS, and application usage surpassing 90 % . Incorporating the inertial measurement units significantly improved the accuracy of all question types, increasing from a maximum of 76 % to 90.99 % , while also enhancing the True Positive Rate from 0.79 to 0.99 compared to a previous study. This research presents a promising lightweight bi-model fallback authentication technique that leverages dynamic security questions and inertial measurement units data, demonstrating its effectiveness for enhancing smartphone security.

Tactile stimulation designs adapted to clinical settings result in reliable fMRI-based somatosensory digit maps.

Movement constraints in stroke survivors are often accompanied by additional impairments in related somatosensory perception. A complex interplay between the primary somatosensory and motor cortices is essential for adequate and precise movements. This necessitates investigating the role of the primary somatosensory cortex in movement deficits of stroke survivors. The first step towards this goal could be a fast and reliable functional Magnetic Resonance Imaging (fMRI)-based mapping of the somatosensory cortex applicable for clinical settings. Here, we compare two 3 T fMRI-based somatosensory digit mapping techniques adapted for clinical usage in seven neurotypical volunteers and two sessions, to assess their validity and retest-reliability. Both, the traveling wave and the blocked design approach resulted in complete digit maps in both sessions of all participants, showing the expected layout. Similarly, no evidence for differences in the volume of activation, nor the activation overlap between neighboring activations could be detected, indicating the general feasibility of the clinical adaptation and their validity. Retest-reliability, indicated by the Dice coefficient, exhibited reasonable values for the spatial correspondence of single digit activations across sessions, but low values for the spatial correspondence of the area of overlap between neighboring digits across sessions. Parameters describing the location of the single digit activations exhibited very high correlations across sessions, while activation volume and overlap only exhibited medium to low correlations. The feasibility and high retest-reliabilities for the parameters describing the location of the single digit activations are promising concerning the implementation into a clinical context to supplement diagnosis and treatment stratification in upper limb stroke patients.

Nitrate and Nitrite Concentrations in Fingertip Serum Following Beetroot Juice Ingestion Correlate with Those in Venous Plasma.

Dietary nitrate (NO3-) supplementation can offer health benefit and improve exercise performance by increasing nitric oxide (NO) through NO3--nitrite (NO2-)-NO pathway. Individuals may benefit from dietary NO3- supplementation by monitoring blood [NO3-] and [NO2-], although a simple and practical method for assessing blood [NO3-] and [NO2-] has not been established. We examined whether fingertip serum samples could substitute for venous plasma samples in assessing [NO3-] and [NO2-]. Ten young adults consumed 140 mL of nitrate-rich beetroot juice. Fingertip serum and venous plasma samples were collected at baseline and every hour for up to 4 h after ingestion. [NO3-] and [NO2-] were similar between samples at baseline, whereas they were higher in fingertip serum throughout the post-ingestion periods. Significant correlations existed between fingertip serum vs. venous plasma for both [NO3-] and [NO2-] throughout post-drink periods, except [NO3-] assessed at 2 and 4 h after ingestion of beetroot juice. We show that although fingertip serum [NO3-] and [NO2-] overestimate those measured by venous plasma after dietary NO3- intake (125-141% and 156-183% of venous values), [NO3-] and [NO2-] in fingertip serum samples may be utilized for assessing blood [NO3-] and [NO2-] levels, although [NO3-] assessment may lack precision compared to [NO2-].

Task demands modulate distal limb handedness: A comparative analysis of prehensile synergies of the dominant and non-dominant hand.

The dynamic dominance hypothesis of handedness suggests a distinct control strategy for the dominant and the non-dominant limb. The hypothesis demonstrated that the dominant proximal limb is tuned for optimal trajectory control while the non-dominant limb is tuned for a stable grasp. Whether the hypothesis can be extended to distal segments like fingers, especially during a five-fingered grasp, has been studied little. To examine this, an attempt was made to compare the prehensile synergies and force magnitudes of the dominant (DOM) and non-dominant hands (NDOM) during a 5-fingered prehension task. Participants traced a trapezoidal and inverse trapezoidal path with their thumbs on a sliding platform while holding a handle in static equilibrium. The DOM hand performed better only in the inverse trapezoid condition, exhibiting a reduced grip force and increased synergy index aligning with the dynamic dominance hypothesis. No differences were observed for the trapezoid condition, likely due to reduced task demands. The study also explored changes in anticipatory synergy adjustments between the DOM and NDOM hands, but the differences were non-significant. Overall, the DOM hand demonstrated better force coordination than the NDOM hand in challenging conditions. Applications of the study in the objective assessment of handedness were proposed.

Dual-ratio approach to pulse oximetry and the effect of skin tone.

Significance: Pulsatile blood oxygen saturation ( SpO 2 ) via pulse oximetry is a valuable clinical metric for assessing oxygen delivery. Individual anatomical features, including skin tone, may affect current optical pulse oximetry methods. Aim: We developed an optical pulse oximetry method based on dual-ratio (DR) measurements to suppress individual anatomical confounds on SpO 2 . Approach: We designed a DR-based finger pulse oximeter, hypothesizing that DR would suppress confounds from optical coupling and superficial tissue absorption. This method is tested using Monte Carlo simulations and in vivo experiments. Results: Different melanosome volume fractions in the epidermis, a surrogate for skin tone, cause changes in the recovered SpO 2 on the order of 1% in simulation and in vivo. Different heterogeneous pulsatile hemodynamics cause greater changes on the order of 10% in simulations. SpO 2 recovered with DR measurements showed less variability than the traditional single-distance (SD) transmission method. Conclusions: For the models and methods considered here, SpO 2 measurements are strongly impacted by heterogeneous pulsatile hemodynamics. This variability may be larger than the skin tone bias, which is a known confound in SpO 2 measurements. The partial suppression of variability in the SpO 2 recovered by DR suggests the promise of DR for pulse oximetry.

Guillain-Barré syndrome with overlap between the finger drop variant and acute bulbar palsy: a case report.

BACKGROUND: Guillain-Barré syndrome (GBS) is a clinically heterogenous disease and encompasses several distinct clinical variants. Overlap between these variants can pose a diagnostic challenge. We report a case of finger drop variant and acute bulbar palsy overlap as an unusual manifestation of GBS. CASE PRESENTATION: An 81-year-old man presented with dysarthria, dysphagia, and upper limb weakness. Neurological examination revealed impaired tongue protrusion, the finger drop sign, and diminished brachioradial and triceps muscle reflexes. Nerve conduction studies showed reduced amplitudes and decreased velocities in the median and ulnar nerves. Cerebrospinal fluid analysis revealed albuminocytological dissociation and an anti-ganglioside antibody study revealed positivity for GM1, asialo-GM1, GT1a, GD1b, and GQ1b. As GBS was suspected, we initiated intravenous immunoglobulin treatment, resulting in gradual improvement within the next 3 weeks. CONCLUSION: To the best of our knowledge, this is the first reported case of an overlap between the finger drop variant and acute bulbar palsy in GBS, highlighting the importance of considering GBS when patients present with a combination of atypical symptoms. Anti-ganglioside antibodies can be helpful and add diagnostic value in these complex cases.

How to Make the Skin Contact Area Controllable by Optical Calibration in Wearable Tactile Displays of Softness.

Virtual reality systems may benefit from wearable (fingertip-mounted) haptic displays capable of rendering the softness of virtual objects. According to neurophysiological evidence, the easiest reliable way to render a virtual softness is to generate purely tactile (as opposed to kinaesthetic) feedback to be delivered via a finger-pulp-interfaced deformable surface. Moreover, it is necessary to control not only the skin indentation depth by applying quasi-static (non-vibratory) contact pressures, but also the skin contact area. This is typically impossible with available devices, even with those that can vary the contact area, because the latter cannot be controlled due to the complexity of sensing it at high resolutions. This causes indetermination on an important tactile cue to render softness. Here, we present a technology that allows the contact area to be open-loop controlled via personalised optical calibrations. We demonstrate the solution on a modified, pneumatic wearable tactile display of softness previously described by us, consisting of a small chamber containing a transparent membrane inflated against the finger pulp. A window on the device allowed for monitoring the skin contact area with a camera from an external unit to generate a calibration curve by processing photos of the skin membrane interface at different pressures. The solution was validated by comparisons with an ink-stain-based method. Moreover, to avoid manual calibrations, a preliminary automated procedure was developed. This calibration strategy may be applied also to other kinds of displays where finger pulps are in contact with transparent deformable structures.

Investigating the role of auditory cues in modulating motor timing: insights from EEG and deep learning.

Research on action-based timing has shed light on the temporal dynamics of sensorimotor coordination. This study investigates the neural mechanisms underlying action-based timing, particularly during finger-tapping tasks involving synchronized and syncopated patterns. Twelve healthy participants completed a continuation task, alternating between tapping in time with an auditory metronome (pacing) and continuing without it (continuation). Electroencephalography data were collected to explore how neural activity changes across these coordination modes and phases. We applied deep learning methods to classify single-trial electroencephalography data and predict behavioral timing conditions. Results showed significant classification accuracy for distinguishing between pacing and continuation phases, particularly during the presence of auditory cues, emphasizing the role of auditory input in motor timing. However, when auditory components were removed from the electroencephalography data, the differentiation between phases became inconclusive. Mean accuracy asynchrony, a measure of timing error, emerged as a superior predictor of performance variability compared to inter-response interval. These findings highlight the importance of auditory cues in modulating motor timing behaviors and present the challenges of isolating motor activation in the absence of auditory stimuli. Our study offers new insights into the neural dynamics of motor timing and demonstrates the utility of deep learning in analyzing single-trial electroencephalography data.

Pulse transmission time and amplitude of digital pulse wave determined by fingertip plethysmography as a surrogate marker of brachial artery flowmediated dilatation.

OBJECTIVE: To assess the changes in blood vessel stiffness and digital pulse wave amplitude because of flowmediated dilatation, and to explore how these two variables change when endothelial dysfunction is experimentally induced. METHODS: The experimental study was conducted at the departments of physiology at the College of Medicine, Mustansiriyah University, and the College of Medicine, Al-Iraqia University, Baghdad, Iraq, from October 14, 2021, to May 31, 2022, and comprised healthy young males who were subjected to the flow-mediated dilatation technique on the left brachial artery. Pulse transit time and the amplitude of the digital pulse wave were measured during reactive hyperaemia for 2.5 minutes from the left middle finger using a piezoelectric pressure sensor and a simultaneous Lead I electrocardiogram. Endothelial dysfunction (ED) was induced by oscillatory and retrograde shear rates. The correlation between variables was calculated in Excel running on the Windows operating system. RESULTS: There were 10 second-year medical students with mean age 22±0 years and mean body mass index 25.7±4.8kg/m2. During reactive hyperaemia, pulse transit time was significantly increased by 3-5% in both normal endothelium and experimentally induced endothelial dysfunction relative to the pre-occluded artery, and the difference was not significant (p>0.05). Digital pulse wave amplitude increased significantly in normal endothelium relative to the pre-occluded artery (p<0.05), but not in experimentally-induced endothelial dysfunction (p>0.05). CONCLUSIONS: The pulse transit time and digital pulse wave amplitudes of the photo plethysmography signal may be used to detect changes in vessel wall diameter and tone throughout the reactive hyperaemia process. Digital pulse wave amplitude was better able to detect experimentally-induced endothelial dysfunction, as assessed by the flowmediated dilatation protocol, than pulse transit time.