Tag: blood vessels

Short, Light Exercises for Children Improve Cerebral Blood Flow

Photo by Annie Spratt on Unsplash

Enhancing prefrontal cortex (PFC) cognitive functions requires identifying suitable exercises that increase cerebral blood flow. A recent study using functional near-infrared spectroscopy found that short-duration, low-intensity physical exercises, except static stretching with monotonous movements, increased oxygenated haemoglobin (oxy-Hb) levels, thereby activating the PFC and enhancing blood flow in children. This study marks a significant step toward improving both the physical and mental health of children.

Cognitive functions, also known as intellectual functions, encompass thinking, understanding, memory, language, computation, and judgment, and are performed in the cerebrum. The prefrontal cortex (PFC), located in the frontal lobe of the cerebral cortex, handles these functions. Studies have shown that exercise improves cognitive function through mechanisms such as enhanced cerebral blood flow, structural changes in the brain, and promotion of neurogenesis. However, 81% of children globally do not engage in enough physical activity, leading to high levels of sedentary behavior and insufficient exercise. This lack of physical activity raises concerns about its negative impact on children’s healthy brain development and cognitive function.

A recent study from Waseda University published in Scientific Reports, by doctoral student Takashi Naito from the Graduate School of Sport Sciences, along with Professors Kaori Ishii and Koichiro Oka from the Faculty of Sport Sciences, offers insights into potential solutions. The study investigated the effects of short-duration and light-intensity exercise on increasing cerebral blood flow in children. “Our goal is to develop a light-intensity exercise program that is accessible to everyone, aiming to enhance brain function and reduce children’s sedentary behaviour. We hope to promote and implement this program in schools through collaborative efforts,” says Naito.

To enhance cognitive performance, it is essential to develop exercise programs that increase cerebral blood flow. While previous studies have established the benefits of moderate-to-vigorous exercise on cognitive functions, changes in cerebral blood flow during light-intensity exercise, particularly in children, is yet to be investigated. To address this gap, the team conducted an experimental study to examine the effects of short-term, light-intensity exercises on prefrontal cortex (PFC) hemodynamics. They focused on exercises that can be easily performed on the spot without special equipment, such as stretching. Functional near-infrared spectroscopy (fNIRS), an imaging technique that measures changes in cerebral blood flow through oxy-Hb concentrations, was used for this purpose.

The study enrolled 41 healthy children ranging from fifth-grade elementary to third-year junior high school students. The children were taught seven different types of low-intensity exercises along with associated safety measures. These exercises included Upward Stretch, Shoulder Stretch, Elbow Circles, Trunk Twist, Washing Hands, Thumb and Pinky, and Single-leg Balance. The exercises were performed while seated except Single-leg Balance, with movement patterns lasting for 10 and 20 seconds. Researchers recorded and compared oxy-Hb levels at rest and during exercise.

The study’s results were highly promising, showing a significant increase in oxy-Hb levels in multiple regions of the PFC during all forms of exercise compared to the resting state. However, no significant change in oxy-Hb levels was observed during static stretching with movement in one direction. “By combining the types of exercise that easily increase blood flow in the PFC identified in this study, it is possible to develop an exercise program that everyone can easily engage in to improve children’s executive functions. It may also be used in the future to prevent cognitive decline in adults and the elderly,” explains Naito optimistically.

In conclusion, this groundbreaking study represents a significant step forward in combating sedentary lifestyles and activating brain functions in children, thereby supporting their physical and mental growth. Although this study demonstrated that even short-duration, low-intensity exercise can increase cerebral blood flow in the prefrontal cortex, future research is needed to confirm whether such exercises actually lead to improved cognitive function.

Source: Waseda University

Blood Vascular Network Retains the ‘Memory’ of a Stroke

Credit: American Heart Association

A study into the structure of blood vascular network structure found that it is dynamic and can adapt to external factors, resulting in a kind of memory of certain events such as an ischaemic stroke. In particular, the study researchers found that rarely used connections incrementally weaken until they disappear eventually.

Researchers from the Max Planck Institute for Dynamics and Self-Organization in Göttingen and the Technical University of Munich used computer simulations to model vascular networks and identified adaptation rules for their connections.

“We found that the strength of a connection within a network depends on the local flow,” explained Karen Alim, corresponding author of the study. “This means that links with a low flow below a certain threshold will decay more and more until they eventually vanish,” she continued. Since the limited amount of material available to build the vascular system needs to be efficiently used, this mechanism offers an elegant way to streamline the vascular system.

Persistent changes in the network

Once a connection has become very weak due to a low flow rate, recovering that connection is very difficult. For example, a blood vessel blockage of the type that could lead to an ischaemic stroke. During an ischaemic stroke, some blood vessels in the affected region are weakened by the blockage.

“We found that in such a case, adaptations in the network are permanent and are maintained after the obstacle is removed. One can say that the network prefers to reroute the flow through existing stronger connections instead of re-growing weaker connections – even if the flow would require the opposite,” explained Komal Bhattacharyya, principal author of the study.

The researchers have thus shown that blood flow permanently changes even after successful removal of the clot. This memory capability of networks can also be found in other living systems: for example, the slime mould Physarum polycephalum uses its adaptive network to navigate its environment based on imprints by food stimuli, as demonstrated previously.

The study was published in Physical Review Letters.

Source: Max Planck Institute for Dynamics and Self-Organization

Empagliflozin Could Reduce Blood Vessel Dysfunction from Ageing

Red blood cells
Source: Pixabay

Empagliflozin, normally used to reduce blood sugar levels in adults with Type 2 diabetes, may also decrease blood vessel dysfunction associated with ageing such as arteriosclerosis, according to a new study published in the journal GeroScience.

First, the researchers studied the role ageing plays in human blood vessel function and stiffness. Then they evaluated how treatment with the sodium glucose co-transporter 2 (SGLT2) inhibitor empagliflozin improved blood vessel function and reduced arterial stiffness in aged male mice.

“Cardiovascular disease is the main cause of death in older adults in the US,” explained Camila Manrique-Acevedo, MD, associate professor of medicine. “Weight loss, physical activity, antihypertensive therapy and lipid-lowering drugs have shown variable effectiveness at improving blood vessel function and reducing arterial stiffness. But additional approaches are needed to improve vascular health in older adults.”

The study first compared blood vessel function and stiffness in 18 healthy human patients, average age 25, with 18 patients, average age 61. They found the older patients had impaired endothelial function and increased aortic stiffness when compared to the younger patients.

“Our findings in young and older adults confirm previous clinical data demonstrating the impact of aging on blood vessel function and arterial stiffness,” Associate Prof Manrique-Acevedo said. “Importantly, we were able to replicate this data in a rodent model.”

To investigate the effects of empagliflozin on vascular ageing, researchers fed empagliflozin to 72-week-old mice in their diet, while their control group received standard food. After six weeks, researchers discovered the mice given empagliflozin experienced improved blood vessel function, reduced arterial stiffness and other vascular benefits.

“To our knowledge, this is the first study to examine the potential role of SGLT2 inhibition in reversing vascular ageing,” Associate Prof Manrique-Acevedo said. “And our findings highlight the need for further clinical investigations to determine the potential role of SGLT2 inhibition as a therapeutic tool to delay or reverse vascular ageing in humans.”

Source: University of Missouri

Vascular Endothelial Cells Communicate in a Vast Network

Source: Wikimedia CC0

Vascular endothelial cells use a vast network of connections to control all cardiovascular functions, and failures in this network contribute to the risk of developing cardiovascular disease, according to a new study published in PNAS.

It has long been known that the development of these conditions begins with changes in the vascular endothelial cells lining the body’s blood vessels. But why and how changes in endothelial cell function occur is not entirely clear.

Research has revealed that these cells communicate with each other using a sophisticated system. Failures in this communication system may be the first step in the development of cardiovascular disease.

The endothelium, which forms the thin inner layer of cells in blood vessels, regulates blood flow, blood pressure, blood clotting, inflammation and response to disease. On a continual basis, it processes the vast amounts of information held in the composition of blood, and chemicals in the area around each blood vessel to keep the cardiovascular system working properly.

The study identified clusters of cells in the endothelium that are specialised to particular functions and they operate in ‘cliques’. Between cliques, numerous interlinked connections act to convey information, with a high density of connections to protect the system against communication failures. The system bypasses neighbouring cells by use of shortcuts to transmit information quickly over distance.

The endothelial communication network design is in fact remarkably similar to the communication operations of the internet and it is effective for local blood vessel control and global efficiency in determining overall cardiovascular activity. The design is robust, so that communication systems to control cardiovascular activity will not fail even when there is extensive damage.

The findings also indicate that changes in the organisation of communication, rather than behaviour and function of individual cells, may underlie disease.

The researchers addressed the nature of the communication network by using single-cell calcium ion imaging across thousands of endothelial cells in intact blood vessels and applying mathematical network (graph) theory.

Professor John McCarron at Strathclude University said: “Cells in the endothelium are a major target for the control of cardiovascular disease and are often treated as being a uniform population of cells. Our findings show the cells are not uniform but specialised to particular types of function.

“There is a well-organised, rapid and robust communication system that shares information so that co-ordinated responses occur. The communication system offers new targets for therapy development and insights into why developing treatments has proven so difficult.”

Source: University of Strathclyde

How Blood Vessels Change Permeability

Source: Wikimedia CC0

Researchers have made steps toward understanding how blood vessels change permeability, and how they might intervene to restore blood vessel integrity during sepsis, trauma or other conditions.

Sepsis occurs when a patient’s over-activated immune system harms their own tissues. As a result, blood vessels can become ‘leaky’ and can’t adequately supply major organs. The condition is notoriously difficult to treat, and there are no drugs that help stabilize the cell barrier that lines blood vessels.

A protein, HSP27, was previously found by researchers at University of California San Diego to be involved in regulating blood vessel leakage. To help break down or build up blood vessel barrier, cells add and remove chemical tags on HSP27.

The study, reported in Science Signaling, provides new potential targets for the development of drugs that shore up blood vessel barriers, preventing fluid loss.

“This new information will help us home in on the root cause of leaky blood vessels, rather than taking a broad strokes approach that may have many off-target effects,” said senior author JoAnn Trejo, Ph.D., professor of pharmacology and assistant vice chancellor of the Office of Health Sciences Faculty Affairs at UC San Diego School of Medicine.

Blood vessel barriers need to be permeable enough to allow immune cells to squeeze out to reach the site of an infection, for example, but not so much that the situation becomes life-threatening. HSP27 binds to proteins that help form the cell’s “skeleton.” Prof Trejo and colleagues suspect that’s how HSP27 affects blood vessel permeability: by reinforcing the skeleton of cells that maintain the barrier.

Prof Trejo has long studied G-protein-coupled receptors (GPCRs), proteins that are embedded in cell membranes and act as signal transducers for cells. About a third of all therapeutic drugs on the market work because they influence GPCR signals.

In their latest study, the team found that during inflammation, GPCRs tell enzymes called kinases to add chemical (phosphate) tags to HSP27. The tags perturb HSP27’s structure in a way that disrupts blood vessel barriers. When HSP27 reassembles, the barriers recover. The researchers validated their lab studies in mice, where they found that inhibiting HSP27 increases blood vessel leakage.

One problem in targeting GPCRs to treat a disease is that most act as master regulators, influencing many different cell functions. Inhibiting one GPCR may therefore have many unintended consequences. By aiming not at the master GPCR but at individual targets upon which it acts, such as HSP27, Trejo’s team is hoping to enable the development of blood vessel barrier-stabilising drugs that have greater precision and fewer side effects.

“It’s become apparent that you can develop different molecules that can bind to receptor and ‘bias’ them — make them signal in a very specific way to some pathways but not others,” Prof Trejo said. “It’s what we call biased agonism, and it’s a huge advantage for drug development. It means we can develop not just an on/off switch, but a drug that can switch a receptor ‘off’ or eight different types of ‘on.’ We want to be able to tweak which pathways are on and not touch others.”

The team plans to explore additional cell signaling pathways that helps blood vessels build resistance to injury and inflammation.

Source: UC San Diego