scholarly journals Stimulus-evoked changes in cerebral vessel diameter: A study in healthy humans

2017 ◽  
Vol 38 (3) ◽  
pp. 528-539 ◽  
Author(s):  
Alexandre Bizeau ◽  
Guillaume Gilbert ◽  
Michaël Bernier ◽  
Minh Tung Huynh ◽  
Christian Bocti ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Stimulation ◽  
Occipital Lobe ◽  
Vessel Diameter ◽  
Metabolic Demand ◽  
Cerebral Vessel ◽  
Non Invasive ◽  
Healthy Humans ◽  
Induced Changes ◽  
High Metabolic Demand

The high metabolic demand of neuronal tissue, coupled with its relatively low energy storage capacity, requires that increases in neuronal activation are quickly matched with increased blood flow to ensure efficient supply of oxygen and nutrients to the tissue. For this to occur, dilation of nearby arterioles must be coordinated with the dilation of larger upstream feeding arteries. As it stands, the exact spatial extent of such dilation in humans is unknown. Using non-invasive time-of-flight magnetic resonance angiography in healthy participants, we developed an automatic methodology for reconstructing cerebral arterial vessels and quantifying their diameter on a voxel-by-voxel basis. Specifically, we isolated the posterior cerebral artery (PCA) supplying each occipital lobe and quantified its vasodilation induced by visual stimulation. Stimulus-induced changes were strongest (∼30%) near primary visual cortex and progressively decreased in a non-linear fashion as a function of distance. Surprisingly, weak – albeit significant – changes (∼2%) were observed ∼70 mm from the visual cortex. This demonstrates that visual stimulation modulates vascular tone along the bulk of the PCA segment, and thus may have important implications for our understanding of functional hyperemia in healthy and diseased states.

Increased high-frequency heart rate variability during insulin-induced hypoglycaemia in healthy humans

2004 ◽  
Vol 106 (6) ◽  
pp. 583-588 ◽  
Author(s):  
Hartmut SCHÄCHINGER ◽  
Johannes PORT ◽  
Stuart BRODY ◽  
Lilly LINDER ◽  
Frank H. WILHELM ◽  
...  
Keyword(s):  
Heart Rate ◽  
High Frequency ◽  
Concomitant Increase ◽  
Plasma Adrenaline ◽  
Non Invasive ◽  
Hyperinsulinaemic Clamp ◽  
Healthy Humans ◽  
Plasma Insulin Levels ◽  
Single Blind ◽  
Cardiac Autonomic Activity

Despite causing sympathetic activation, prolonged hypoglycaemia produces little change in HR (heart rate) in healthy young adults. One explanation could be concurrent parasympathetic activation, resulting in unchanged net effects of autonomic influences. In the present study, hypoglycaemic (2.7 mmol/l) and normoglycaemic (4.7 mmol/l) hyperinsulinaemic clamp studies were performed after normoglycaemic baseline clamp periods with 15 healthy volunteers (seven male; mean age, 27 years) on two occasions in a randomized single-blind cross-over design. Non-invasive indices of cardiac autonomic activity and hormones were measured at baseline and 1 h after the beginning of hypoglycaemia or control normoglycaemia. Plasma insulin levels and mean HR were similar during both conditions. During hypoglycaemia, there was a 485% increase in plasma adrenaline (epinephrine). A shortening of the pre-ejection period by 45% suggested strong sympathetic cardiac activation. High-frequency (0.15–0.45 Hz) HRV (HR variability) increased, indicating a concomitant increase in parasympathetic tone. Thus, during hypoglycaemia-induced sympathetic cardiac activation in healthy adults, parasympathetic mechanisms are involved in stabilizing mean HR.

scholarly journals Non-invasive stimulation of vagal afferents reduces gastric frequency

2019 ◽  
Author(s):  
Vanessa Teckentrup ◽  
Sandra Neubert ◽  
João C. P. Santiago ◽  
Manfred Hallschmid ◽  
Martin Walter ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Vagus Nerve ◽  
Energy Homeostasis ◽  
Resting Energy Expenditure ◽  
Vagal Afferents ◽  
Metabolic Effects ◽  
Net Energy ◽  
Non Invasive ◽  
Induced Changes ◽  
Stimulation Of

AbstractMetabolic feedback between the gut and the brain relayed via the vagus nerve contributes to energy homeostasis. We investigated in healthy adults whether non-invasive stimulation of vagal afferents impacts energy homeostasis via efferent effects on metabolism or digestion. In a randomized crossover design, we applied transcutaneous auricular vagus nerve stimulation (taVNS) while recording efferent metabolic effects using simultaneous electrogastrography (EGG) and indirect calorimetry. We found that taVNS reduced gastric myoelectric frequency (p =.008), but did not alter resting energy expenditure. We conclude that stimulating vagal afferents induces gastric slowing via vagal efferents without acutely affecting net energy expenditure at rest. Collectively, this highlights the potential of taVNS to modulate digestion by activating the dorsal vagal complex. Thus, taVNS-induced changes in gastric frequency are an important peripheral marker of brain stimulation effects.

scholarly journals Heat Shock Protein 90 as Therapeutic Target for CVDs and Heart Ageing

2022 ◽  
Vol 23 (2) ◽  
pp. 649
Author(s):  
Siarhei A. Dabravolski ◽  
Vasily N. Sukhorukov ◽  
Vladislav A. Kalmykov ◽  
Nikolay A. Orekhov ◽  
Andrey V. Grechko ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Molecular Chaperones ◽  
Heat Shock Protein 90 ◽  
Misfolded Proteins ◽  
Heart Cells ◽  
Metabolic Demand ◽  
Heart Protection ◽  
High Metabolic Demand

Cardiovascular diseases (CVDs) are the leading cause of death globally, representing approximately 32% of all deaths worldwide. Molecular chaperones are involved in heart protection against stresses and age-mediated accumulation of toxic misfolded proteins by regulation of the protein synthesis/degradation balance and refolding of misfolded proteins, thus supporting the high metabolic demand of the heart cells. Heat shock protein 90 (HSP90) is one of the main cardioprotective chaperones, represented by cytosolic HSP90a and HSP90b, mitochondrial TRAP1 and ER-localised Grp94 isoforms. Currently, the main way to study the functional role of HSPs is the application of HSP inhibitors, which could have a different way of action. In this review, we discussed the recently investigated role of HSP90 proteins in cardioprotection, atherosclerosis, CVDs development and the involvements of HSP90 clients in the activation of different molecular pathways and signalling mechanisms, related to heart ageing.

scholarly journals Optimizing mitochondrial maintenance in extended neuronal projections

2021 ◽  
Vol 17 (6) ◽  
pp. e1009073
Author(s):  
Anamika Agrawal ◽  
Elena F. Koslover
Keyword(s):  
Steady State ◽  
Neurodegenerative Disorders ◽  
Quantitative Model ◽  
Organelle Transport ◽  
Optimal Distribution ◽  
Metabolic Demand ◽  
Mitochondrial Homeostasis ◽  
Fresh Material ◽  
New Material ◽  
High Metabolic Demand

Neurons rely on localized mitochondria to fulfill spatially heterogeneous metabolic demands. Mitochondrial aging occurs on timescales shorter than the neuronal lifespan, necessitating transport of fresh material from the soma. Maintaining an optimal distribution of healthy mitochondria requires an interplay between a stationary pool localized to sites of high metabolic demand and a motile pool capable of delivering new material. Interchange between these pools can occur via transient fusion / fission events or by halting and restarting entire mitochondria. Our quantitative model of neuronal mitostasis identifies key parameters that govern steady-state mitochondrial health at discrete locations. Very infrequent exchange between stationary and motile pools optimizes this system. Exchange via transient fusion allows for robust maintenance, which can be further improved by selective recycling through mitophagy. These results provide a framework for quantifying how perturbations in organelle transport and interactions affect mitochondrial homeostasis in neurons, a key aspect underlying many neurodegenerative disorders.

STATUS OF OXIDANT (MDA) ANTIOXIDANT (SOD) IN FIRST AND THIRD TRIMESTER OF NORMAL PREGNANCY IN TERTIARY CENTER OF CENTRAL INDIA

2021 ◽  
pp. 12-14
Author(s):  
Tamrakar Seema ◽  
Sachdeva Payasvi ◽  
Tripathi Rashmi
Keyword(s):  
Oxidative Stress ◽  
Pregnant Women ◽  
Central India ◽  
Normal Pregnancy ◽  
Metabolic Demand ◽  
Third Trimester ◽  
Dynamic Changes ◽  
Tertiary Center ◽  
Antioxidant Supplements ◽  
High Metabolic Demand

INTRODUCTION: Pregnancy is associated with high metabolic demand and increased demand for tissue oxygen. Consequently increased production of reactive oxygen species. This leads in increased oxidative stress and decreases antioxidant status during gestational age of normal pregnant women. Aim: Aim of this study was to evaluate the level of oxidant and antioxidant in 1st and 3rd trimester of normal pregnant women. MATERIAL AND METHODS: The present study included total 150 cases attended ANC Clinic at the department of Gynae LNMC & J K Hospital was screened for the study. Level of MDA was estimated by Jean et al and SOD was Marklund and Marklund. RESULTS: Findings were, that there was signicantly increase in Malondialdehyde levels (p<0.001) and signicantly decrease in superoxide dismutase activities (P<0.001) in 1st and 3rd trimester of normal pregnant women. Conclusion: present study concludes that there was difference in oxidative status due to dynamic changes. During pregnancy oxidative stress is increased and antioxidant decreased that can be fatal to the health of the mother and the fetus. Therefore antioxidant supplements should be prescribed in early pregnancy to prevent the overwhelming of oxidative stress in pregnant females.

Neutralization of TNF does not influence endotoxininduced changes in thyroid hormone metabolism in humans

1999 ◽  
Vol 276 (2) ◽  
pp. R357-R362 ◽  
Author(s):  
Tom van der Poll ◽  
Erik Endert ◽  
Susette M. Coyle ◽  
Jan M. Agosti ◽  
Stephen F. Lowry
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Stimulating Hormone ◽  
Hormone Metabolism ◽  
Thyroid Hormone Metabolism ◽  
Healthy Humans ◽  
Transient Rise ◽  
Induced Changes ◽  
Necrosis Factor ◽  
Control Study

To determine the role of tumor necrosis factor (TNF) in endotoxin-induced changes in plasma thyroid hormone and thyroid-stimulating hormone (TSH) concentrations, 24 healthy postabsorptive humans were studied on a control study day ( n= 6), after infusion of a recombinant TNF receptor IgG fusion protein (TNFR:Fc; 6 mg/m2; n = 6) after intravenous injection of endotoxin (2 ng/kg; n = 6), or after administration of endotoxin with TNFR:Fc ( n = 6). Administration of TNFR:Fc alone did not affect thyroid hormone or TSH levels when compared with the control day. Endotoxin induced a transient rise in plasma TNF activity (1.5 h: 219 ± 42 pg/ml), which was completely prevented by TNFR:Fc ( P < 0.05). After endotoxin administration, plasmal-thyroxine (T4), free T4, 3,5,3′-triiodothyronine (T3), and TSH were lower and 3,3′,5′-triiodothyronine was higher than on the control day (all P < 0.05). Coinfusion of TNFR:Fc with endotoxin did not influence these endotoxin-induced changes. Our results suggest that endogenous TNF does not play an important role in the alterations in plasma thyroid hormone and TSH concentrations induced by mild endotoxemia in healthy humans.

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