Blood Flow In People Research Articles

Effects of diazepam on hippocampal blood flow in people at clinical high risk for psychosis

Elevated hippocampal perfusion has been observed in people at clinical high risk for psychosis (CHR-P). Preclinical evidence suggests that hippocampal hyperactivity is central to the pathophysiology of psychosis, and that peripubertal treatment with diazepam can prevent the development of psychosis-relevant phenotypes. The present experimental medicine study examined whether diazepam can normalize hippocampal perfusion in CHR-P individuals. Using a randomized, double-blind, placebo-controlled, crossover design, 24 CHR-P individuals were assessed with magnetic resonance imaging (MRI) on two occasions, once following a single oral dose of diazepam (5 mg) and once following placebo. Regional cerebral blood flow (rCBF) was measured using 3D pseudo-continuous arterial spin labeling and sampled in native space using participant-specific hippocampus and subfield masks (CA1, subiculum, CA4/dentate gyrus). Twenty-two healthy controls (HC) were scanned using the same MRI acquisition sequence, but without administration of diazepam or placebo. Mixed-design ANCOVAs and linear mixed-effects models were used to examine the effects of group (CHR-P placebo/diazepam vs. HC) and condition (CHR-P diazepam vs. placebo) on rCBF in the hippocampus as a whole and by subfield. Under the placebo condition, CHR-P individuals (mean [±SD] age: 24.1 [±4.8] years, 15 F) showed significantly elevated rCBF compared to HC (mean [±SD] age: 26.5 [±5.1] years, 11 F) in the hippocampus (F(1,41) = 24.7, pFDR < 0.001) and across its subfields (all pFDR < 0.001). Following diazepam, rCBF in the hippocampus (and subfields, all pFDR < 0.001) was significantly reduced (t(69) = −5.1, pFDR < 0.001) and normalized to HC levels (F(1,41) = 0.4, pFDR = 0.204). In conclusion, diazepam normalized hippocampal hyperperfusion in CHR-P individuals, consistent with evidence implicating medial temporal GABAergic dysfunction in increased vulnerability for psychosis.

Six-month combined aerobic and resistance exercise program enhances 6-minute walk test and physical fitness in people with peripheral arterial disease: A pilot study

BackgroundExercise therapy is a recognized non-pharmacological intervention for peripheral arterial disease (PAD); however, the effects of combined exercise remain under investigation. This study aimed to compare the effects of a 6-month combined supervised exercise program (SUP) with a usual care (UC) approach on walking ability, physical fitness, and peripheral blood flow in people with PAD and claudication. MethodsTwenty-three male participants (Age=64.1 ± 6.2years and ABI=0.58±0.07) with PAD and claudication were assigned to either the SUP group (n = 10), engaging in structured supervised treadmill walking combined with three resistance exercises, three times a week, or the UC group (n = 13), receiving advice to walk. The primary outcome measure was walking ability, with assessments conducted at baseline (M0), after 3 months (M3), and 6 months (M6). ResultsAfter the 6-month intervention, the SUP group exhibited significant improvements in absolute claudication time (ACT, p = 0.045), maximal walking time (MWT, p = 0.045), maximal walking distance (MWD, p = 0.027), and pause duration (p = 0.045) during the 6-minute walk test (6MWT), when compared to the UC group. Over time, a significant increase in walking speed during the 6MWT (Speed6MWT, p = 0.001) and walking speed without claudication (SpeedNoC, p < 0.001) was found, although no significant differences were found between the groups. The SUP group increased by 0.8 km/h in both Speed6MWT and SpeedNoC, while the UC group increased by 0.3 km/h and 0.6 km/h, respectively. Despite claudication consistently occurring at the same time, the SUP group demonstrated an improved tolerance to pain or a better understanding of pain, enabling them to walk longer distances at higher speeds. A positive effect of SUP was found for chair sit-and-reach test (p = 0.023), percentage of fat mass (p = 0.048), fat-free mass (p = 0.040), and total body water (p = 0.026), suggesting potential benefits attributed to the resistance strength exercises. ConclusionA 6-month combined treadmill and resistance exercise program improved walking ability, walking speed, lower body and lower back flexibility, and body composition in people with PAD and claudication.

Increased Peripheral Inflammation Is Associated With Structural Brain Changes and Reduced Blood Flow in People With Virologically Controlled HIV.

While antiretroviral therapy (ART) has improved outcomes for people with HIV (PWH), brain dysfunction is still evident. Immune activation and inflammation remain elevated in PWH receiving ART, thereby contributing to morbidity and mortality. Previous studies demonstrated reduced functional and structural changes in PWH; however, underlying mechanisms remain elusive. Our cohort consisted of PWH with ART adherence and viral suppression ( < 50 copies/mL; N = 173). Measurements included immune cell markers of overall immune health (CD4/CD8 T-cell ratio) and myeloid inflammation (CD16+ monocytes), plasma markers of inflammatory status (soluble CD163 and CD14), and structural and functional neuroimaging (volume and cerebral blood flow [CBF], respectively). Decreased CD4/CD8 ratios correlated with reduced brain volume, and higher levels of inflammatory CD16+ monocytes were associated with reduced brain volume in total cortex and gray matter. An increase in plasma soluble CD14-a marker of acute peripheral inflammation attributed to circulating microbial products-was associated with reduced CBF within the frontal, parietal, temporal, and occipital cortices and total gray matter. CD4/CD8 ratio and number of CD16+ monocytes, which are chronic immune cell markers, are associated with volumetric loss in the brain. Additionally, this study shows a potential new association between plasma soluble CD14 and CBF.

Exercise Training to Improve Brain Health in Older People Living With HIV: Study Protocol for a Randomized Controlled Trial.

With the advent of antiretrovirals, people living with HIV are living near-normal lifespans. However, people living with HIV are at greater risk of experiencing cognitive impairment and reduced brain integrity despite well-controlled viremia. A robust literature supports exercise interventions as a method of improving cognition and structural brain integrity in older individuals without HIV. The effects of exercise on cardiometabolic, neurocognitive, and neural structures in middle-aged to older people living with HIV are less well known, with few prospective studies examining these measures. This prospective randomized clinical trial will examine the effects of a 6-month exercise training intervention compared to a 6-month stretching intervention (control) on cardiorespiratory fitness, physical function and strength, cognition, and neuroimaging measures of brain volumes and cerebral blood flow in people living with HIV. Sedentary middle-aged to older people living with HIV (ages≥40; n=150) with undetectable HIV viral load (<20 copies/mL) will be enrolled in the study. At the baseline and final visit, fasting plasma lipid, insulin, glucose, and brain neurotrophic factor concentrations; cardiorespiratory fitness; cognitive performance; brain volumes; and cerebral blood flow via a magnetic resonance imaging scan will be measured. Participants will be randomized in a 2:1 ratio to either the exercise or control stretching intervention. All participants will complete their assigned programs at a community fitness center 3 times a week for 6 months. A professional fitness trainer will provide personal training guidance at all sessions for individuals enrolled in both arms. Individuals randomized to the exercise intervention will perform endurance and strength training exercises, while those randomized to the control intervention will perform stretches to increase flexibility. A midpoint visit (at 3 months) will assess cognitive performance, and at the end point visit, subjects will undergo cardiorespiratory fitness and cognition testing, and a magnetic resonance imaging scan. Physical activity throughout the duration of the trial will be recorded using an actigraph. Recruitment and data collection are complete as of December 2020. Data processing, cleaning, and organization are complete as of December 2021. Data analysis began in January 2022, with the publication of study results for primary aims 1 and 2 expected by early 2023. This study will investigate the effects of a 6-month aerobic and resistance exercise training intervention to improve cardiometabolic risk factors, cognitive performance, cerebral structure, and blood flow in sedentary people living with HIV. Results will inform clinicians and patients of the potential benefits of a structured aerobic exercise training program on the cognitive, functional, and cardiometabolic health status of older people living with HIV. Assessment of compliance will inform the development and implementation of future exercise programs for people living with HIV. ClinicalTrials.gov NCT02663934; https://clinicaltrials.gov/ct2/show/NCT02663934. DERR1-10.2196/41421.

Kidney oxygenation, perfusion and blood flow in people with and without type 1 diabetes.

We used magnetic resonance imaging (MRI) to study kidney energetics in persons with and without type 1 diabetes (T1D). In a cross-sectional study, 15 persons with T1D and albuminuria and 15 non-diabetic controls (CONs) underwent multiparametric MRI (3 Tesla Philips Scanner) to quantify renal cortical and medullary oxygenation (R2*, higher values correspond to higher deoxyhaemoglobin concentration), renal perfusion (arterial spin labelling) and renal artery blood flow (phase contrast). Analyses were adjusted for age, sex, systolic blood pressure, plasma haemoglobin, body mass index and estimated glomerular filtration rate (eGFR). Participants with T1D had a higher median (Q1; Q3) urine albumin creatinine ratio (UACR) than CONs [46 (21; 58) versus 4 (3; 6) mg/g; P<.0001] and a lower mean±SD eGFR (73±32mL/min/1.73 m2versus 88±15mL/min/1.73 m2; P=.12), although not significantly. Mean medullary R2* was lower in T1D (34±6/sversus 38±5/s; P<.01) corresponding to a higher oxygenation. R2* was not different in the cortex. Cortical perfusion was lower in T1D (163±40versus 224±49mL/100 g/min; P<.001). Renal artery blood flow was lower in T1D than in CONs (360±130versus 430±113mL/min; P=.05). In T1D, lower cortical oxygenation and renal artery blood flow were both associated with higher UACR and lower eGFR (P<.05). Participants with T1D and albuminuria exhibited higher medullary oxygenation than CONs, despite lower cortical perfusion and renal artery blood flow. This might reflect perturbed kidney energetics leading to a higher setpoint of medullary oxygenation in T1D. Lower cortical oxygenation and renal artery blood flow were associated with higher UACR and lower eGFR in T1D.

The effects of different accumulated pressure-time integral stimuli on plantar blood flow in people with diabetes mellitus

BackgroundExercise, especially weight-bearing exercise (e.g. walking), may affect plantar tissue viability due to prolonged repetitive high vertical and high shear pressure stimulus on the plantar tissue, and further induce development of diabetic foot ulcers (DFUs). This study aimed to investigate the effects of different accumulated pressure-time integral (APTI) stimuli induced by walking on plantar skin blood flow (SBF) responses in people with diabetes mellitus (DM).MethodsA repeated measures design was used in this study. Two walking protocols (low APTI (73,000 kPa·s) and high APTI (73,000 × 1.5 kPa·s)) were randomly assigned to ten people with DM and twenty people without DM. The ratio of SBF measured by laser Doppler flowmetry after walking to that before (normalized SBF) was used to express the SBF responses.ResultsAfter low APTI, plantar SBF of people with DM showed a similar response to people without DM (P = 0.91). However, after high APTI, people with DM had a significantly lower plantar SBF compared to people without DM (P < 0.05). In people with DM, plantar SBF in the first 2 min after both APTI stimuli significantly decreased compared to plantar SBF before walking (P < 0.05).ConclusionsPeople with DM had a normal SBF response after low APTI walking but had an impaired SBF response after high APTI walking, which suggests that they should avoid weight-bearing physical activity with intensity more than 73,000 kPa·s and should rest for more than 2 min after weight-bearing physical activity to allow a full vasodilatory response to reduce risk of DFUs.

Obstructive sleep apnea syndrome: functional state of vascular endothelium and features of brain hemodynamics

The aim of the study is to identify the relationships between the functional state of vascular endothelium and regional cerebral blood flow in people of working age with moderate to severe obstructive sleep apnea syndrome. A transverse prospective observational study was conducted. It included 24 patients. Among them were 16 patients of working age with moderate to severe obstructive sleep apnea syndrome who were included in the main study group and 8 patients without sleep disorders in the control group according to polysomnography. The levels of biochemical markers of endothelial dysfunction, the indicators of endothelium-dependent vasodilation of the brachial artery were determined. Single-photon emission computed tomography of the brain was performed using 99mTc-hexamethylpropyleneaminoxime. In the patients of working age with moderate to severe obstructive sleep apnea syndrome, significantly lower average group values of the serum nitric oxide level of 11.7 (6.25‒18.30) μmol/l were detected versus 34.4 (25.33‒41.70) μmol/l in the control group, p &lt; 0.01), as well as higher homocysteine concentrations of 19.4 (15.13‒23.76) μmol/l versus 11.6 (6.40‒ 14.71) μmol/l in the control group, p &lt; 0.05, sP-selectin 176 (142.0‒189.0) ng/ml versus 122 (113.3‒168.5) ng/ml in the control group, p &lt; 0.05, and sE β-selectin 78 (69.0‒121.0) ng/ml versus 52 (43.1‒73.3) ng/ml in the control group, p &lt; 0.05. The data on the correlation of the level of neurohumoral markers of endothelial dysfunction of sP-selectin (p &lt; 0.01) and sE-selectin (p &lt; 0.05) with the degree of impaired regional cerebral blood flow were obtained. A direct relationship was found between the markers of endothelium-dependent vasodilation and regional cerebral blood flow in the frontal segments (p &lt; 0.05), the temporal segment on the right (p &lt; 0.05).

THE ASSESSMENT OF EMOTIONAL STRESS UNDER COGNITIVE LOAD IN MALES WITH A DIFFERENT LEVEL OF PHYSICAL ACTIVITY

Background. In view of the continuous increase in the importance of information technologies in all spheres of society, the problem of the effect of significant cognitive loads that accompany information stress becomes extremely urgent. The article presents an analysis of studies (2018–2019) on resistance to cognitive loads in males with different levels of physical activity. Aim. The article aims to evaluate the dynamics of psychophysiological reactions to cognitive load in males with different levels of physical activity. Materials and methods. Regulatory mechanisms were assessed using the index of functional changes. The simulated load consisted in the Gorbov–Schulte table to be made in the conditions of time deficit, increased motivation and interference. Continuous recording of vascular tone, vascular blood flow, heart rate, electrical skin activity was performed. It is established that a different level of physical activity is specifically associated with the adaptation of a person to a significant cognitive load. Results. The dynamics of skin electrical activity, heart rate, vascular tone and vascular blood flow in people with moderate physical activity reflects optimal reactions to load. Conclusion. Persons systematically involved in physical activity in these conditions have a higher adaptive capacity of the vascular part in comparison with professional athletes and people not engaged in physical activity.

No Immediate Effects of Transcranial Direct Current Stimulation at Various Intensities on Cerebral Blood Flow in People with Multiple Sclerosis.

Animal and transcranial magnetic stimulation motors have evoked potential studies suggesting that the currently used transcranial direct current stimulation (tDCS) intensities produce measurable physiological changes. However, the validity, mechanisms, and general efficacy of this stimulation modality are currently being scrutinized. The purpose of this pilot study was to investigate the effects of dorsolateral prefrontal cortex tDCS on cerebral blood flow. A sample of three people with multiple sclerosis underwent two blocks of five randomly assigned tDCS intensities (1, 2, 3, 4 mA, and sham; 5 min each) and [15O]water positron emission tomography imaging. The relative regional (i.e., areas under the electrodes) and global cerebral blood flow were calculated. The results revealed no notable differences in regional or global cerebral blood flow from the different tDCS intensities. Thus, 5 min of tDCS at 1, 2, 3, and 4 mA did not result in immediate changes in cerebral blood flow. To achieve sufficient magnitudes of intracranial electrical fields without direct peripheral side effects, novel methods may be required.

Sonographic assessment of nerve blood flow in diabetic neuropathy.

To undertake sonographic assessment of nerve blood flow in people with Type 2 diabetes and correlate the findings with neuropathy severity scores and electrophysiological measurements. Median and tibial nerve ultrasound scans were undertaken in 75 people with diabetes and 30 aged-matched controls without diabetes, using a high-resolution linear probe at non-entrapment sites. Nerve blood flow was quantified using power Doppler techniques to obtain the vessel score and the maximum perfusion intensity. Neuropathy severity was assessed using a total neuropathy score. Diabetic nerves had higher rates of nerve blood flow detection (28%) compared to the control group (P < 0.0001). Significant correlations were found between nerve blood flow measurements and nerve size (P <0.001), reported sensory symptoms (P < 0.05) and neuropathy severity scores (P < 0.001). The cohort with diabetes had significantly larger median (8.5 ± 0.3 mm2 vs 7.2 ± 0.1 mm2 ; P < 0.05) and tibial nerves (18.0 ± 0.9 mm2 vs 12.8 ± 0.5 mm2 ; P < 0.05) compared with controls. Peripheral nerve hypervascularity is detectable by ultrasonography in moderate to severe diabetic neuropathy with prominent sensory dysfunction.

DEMOGRAPHICS AND TEMPORAL TRENDS OF IMPLANTABLE VENTRICULAR ASSIST DEVICES IN USA SINCE 2004: AN ANALYSIS OF NIS DATA

A ventricular assist device (VAD) is a mechanical pump used to support heart function and blood flow in people who have advanced heart failure. Left ventricular assist device (LVAD) and a right ventricular assist device (RVAD) are the two basic types of ventricular assist devices used. This study

Effects of Wheelchair Cushions and Pressure Relief Maneuvers on Ischial Interface Pressure and Blood Flow in People With Spinal Cord Injury

ObjectiveTo investigate the effectiveness and interactions of 2 methods of pressure ulcer prevention, wheelchair cushions and pressure relief maneuvers, on interface pressure (IP) and blood flow of the buttocks. DesignWithin-subject repeated measures. SettingRehabilitation center. ParticipantsWheelchair users with a spinal cord injury or disorder (N=17). InterventionsParticipants performed 3 forward leans and 2 sideward leans with different degrees of lean while seated on each of 3 different wheelchair cushions. Main Outcome MeasuresIP measured with a custom sensor and blood flow measured with laser Doppler flowmetry were collected at the ischial tuberosity. ResultsPressure relief maneuvers had a significant main effect on the ischial IP (P<.001); all maneuvers except for the small frontward lean resulted in a significant reduction in IP compared with upright sitting. Blood flow significantly varied across postures (P<.001) with flow during upright sitting and small forward leans being significantly lower than during the full and intermediate leans in both the forward and sideward directions. ConclusionsThe results of the study highlight the importance of positioning wheelchair users in a manner that facilitates in-seat movement. Regardless of the cushion being used, the pressure relief maneuvers resulted in very large reductions in IPs and significant increases in buttock blood flow. Only the small frontward lean was shown to be ineffective in reducing pressure or increasing blood flow. Because these pressure relief maneuvers involved postural changes that can occur during functional activities, these pressure relief maneuvers can become a part of volitional pressure relief and functional weight shifts. Therefore, clinical instruction should cover both as a means to impart sitting behaviors that may lead to better tissue health.

Characterization of regional cerebral blood flow in people with mild cognitive impairment and older adults with cognitive complaints

Characterization of regional cerebral blood flow in people with mild cognitive impairment and older adults with cognitive complaints

The Effect of Monophasic Vs. Biphasic Current on Healing Rate and Blood Flow in People With Pressure and Neuropathic Ulcers

Background: Endothelial dysfunction due to diabetes may be one reason why at least 15% of people with diabetes will eventually develop a lower extremity ulcer with delayed healing and risk of amputation. Recent evidence shows that skin blood flow may be increased with electrical stimulation if treatment is done in a warm room. However, optimal stimulation waveform is unknown. Optimizing the stimulation waveform may increase healing even more. The purpose of this investigation was to compare two electrical waveforms to determine which increased blood flow blood flow and wound healing more in chronic stage III or IV pressure ulcers and in Wagner stage II neuropathic ulcers when using a warm room. Materials and Methods: Forty subjects with chronic pressure or neuropathic ulcers were treated at an outpatient wound center. Twenty were people with neuropathic ulcers and twenty with pressure ulcers. Treatment consisted of biphasic or monophasic electrical stimulation up to 20 mA for 30 minutes, 3x/ week for 4 weeks in a 32°C room. Skin blood flow was measured by a Laser Doppler imager. Results: Subjects with neuropathic ulcers receiving biphasic current had significantly higher healing rate (70.0% ± 32.3%) than those receiving. monophasic current (42% ± 22.3%; p Conclusion: Both patients with neuropathic and pressure ulcers receiving biphasic current demonstrated greater blood flow and healing rates compared with patients receiving monophasic current when treated in a 32°C room.

The Effect of Monophasic Vs. Biphasic Current on Healing Rate and Blood Flow in People With Pressure and Neuropathic Ulcers

The Effect of Monophasic Vs. Biphasic Current on Healing Rate and Blood Flow in People With Pressure and Neuropathic Ulcers

The effect of niacin on facial blood flow in people with an elevated fear of negative evaluation

The vasodilator niacin may provoke greater facial flushing and other symptoms of anxiety in patients with social anxiety disorder than in non-anxious controls. To determine whether this also applies in non-clinical samples, niacin (100mg) or placebo was administered double-blind to 33 young adults and flushing was investigated in relation to fear of negative evaluation (a cardinal feature of social anxiety). Increases in facial blood flow were greater in people with high than low fear of negative evaluation in the niacin condition, but were similar in both groups in the placebo condition. However, changes in pulse rate and ratings of embarrassment, anxiety, blushing and facial heat were similar in both groups in both drug conditions. These findings suggest that the facial vessels of people with a heightened fear of negative evaluation are particularly responsive to niacin under conditions of low anxiety and embarrassment.

New approaches for the evaluation of renal vascular function in diabetes

In this issue of Diabetologia, two new approaches are described for the assessment of intra-renal blood flow in people with diabetes. The first approach used the technique of dynamic assessment of the resistance index (RI) in the renal interlobar arteries before and after administration of sublingual glyceryl trinitrate, and the second used MRI to assess total renal blood flow in relation to mean arterial pressure, thereby enabling direct measurement of overall renal RI. The results of the first study raise the possibility that dynamic evaluation of the intra-renal RI could be used as an early detector of vascular alterations in type 2 diabetes, before the onset of microalbuminuria. The results of the second study suggest that decreases in renal blood flow in people with longstanding type 1 diabetes reflect intra-renal vascular stiffening and raise the possibility that in microalbuminuric patients it may also reflect increased intraglomerular pressure.

The Effects of Contrast Baths on Skin Blood Flow in People with Type 2 Diabetes and Age-Matched Controls

The Effects of Contrast Baths on Skin Blood Flow in People with Type 2 Diabetes and Age-Matched Controls