Month: March 2024

Categories : UncategorizedTags :

How Gamma Rhythm Light and Sound Strips Amyloid in Alzheimer’s Mouse Models

On By ModernMedia
Photo by Fakurian Design on Unsplash

Studies at MIT and elsewhere are producing mounting evidence that light flickering and sound clicking at the gamma brain rhythm frequency of 40Hz can reduce Alzheimer’s disease (AD) progression and treat symptoms in human volunteers as well as lab mice. In a new study in Nature using a mouse model of the disease, researchers at The Picower Institute for Learning and Memory of MIT reveal a key mechanism that may contribute to these beneficial effects: clearance of amyloid proteins, a hallmark of AD pathology, via the brain’s glymphatic system, a recently discovered “plumbing” network parallel to the brain’s blood vessels.

“Ever since we published our first results in 2016, people have asked me how does it work? Why 40Hz? Why not some other frequency?” said study senior author Li-Huei Tsai, Professor of Neuroscience at Picower. “These are indeed very important questions we have worked very hard in the lab to address.”

The new paper describes a series of experiments, led by Mitch Murdock when he was a Brain and Cognitive Sciences doctoral student at MIT, showing that when sensory gamma stimulation increases 40 Hz power and synchrony in the brains of mice, that prompts a particular type of neuron to release peptides. The study results further suggest that those short protein signals then drive specific processes that promote increased amyloid clearance via the glymphatic system.

“We do not yet have a linear map of the exact sequence of events that occurs,” said Murdock, who was jointly supervised by Tsai and co-author and collaborator Ed Boyden, Professor of Neurotechnology at MIT. “But the findings in our experiments support this clearance pathway through the major glymphatic routes.”

From gamma to glymphatics

Because prior research has shown that the glymphatic system is a key conduit for brain waste clearance and may be regulated by brain rhythms, Tsai and Murdock’s team hypothesised that it might help explain the lab’s prior observations that gamma sensory stimulation reduces amyloid levels in Alzheimer’s model mice.

Working with “5XFAD” mice, which genetically model Alzheimer’s, Murdock and co-authors first replicated the lab’s prior results that 40Hz sensory stimulation increases 40Hz neuronal activity in the brain and reduces amyloid levels. Then they set out to measure whether there was any correlated change in the fluids that flow through the glymphatic system to carry away wastes. Indeed, they measured increases in cerebrospinal fluid in the brain tissue of mice treated with sensory gamma stimulation compared to untreated controls. They also measured an increase in the rate of interstitial fluid leaving the brain. Moreover, in the gamma-treated mice he measured increased diameter of the lymphatic vessels that drain away the fluids and measured increased accumulation of amyloid in cervical lymph nodes, which is the drainage site for that flow.

To investigate how this increased fluid flow might be happening, the team focused on the aquaporin 4 (AQP4) water channel of astrocyte cells, which enables the cells to facilitate glymphatic fluid exchange. When they blocked APQ4 function with a chemical, that prevented sensory gamma stimulation from reducing amyloid levels and prevented it from improving mouse learning and memory. And when, as an added test they used a genetic technique for disrupting AQP4, that also interfered with gamma-driven amyloid clearance.

In addition to the fluid exchange promoted by APQ4 activity in astrocytes, another mechanism by which gamma waves promote glymphatic flow is by increasing the pulsation of neighbouring blood vessels. Several measurements showed stronger arterial pulsatility in mice subjected to sensory gamma stimulation compared to untreated controls.

One of the best new techniques for tracking how a condition, such as sensory gamma stimulation, affects different cell types is to sequence their RNA to track changes in how they express their genes. Using this method, Tsai and Murdock’s team saw that gamma sensory stimulation indeed promoted changes consistent with increased astrocyte AQP4 activity.

Prompted by peptides

The RNA sequencing data also revealed that upon gamma sensory stimulation a subset of neurons, called “interneurons,” experienced a notable uptick in the production of several peptides. This was not surprising in the sense that peptide release is known to be dependent on brain rhythm frequencies, but it was still notable because one peptide in particular, VIP, is associated with Alzheimer’s-fighting benefits and helps to regulate vascular cells, blood flow and glymphatic clearance.

Seizing on this intriguing result, the team ran tests that revealed increased VIP in the brains of gamma-treated mice. The researchers also used a sensor of peptide release and observed that sensory gamma stimulation resulted in an increase in peptide release from VIP-expressing interneurons.

But did this gamma-stimulated peptide release mediate the glymphatic clearance of amyloid? To find out, the team ran another experiment: they chemically shut down the VIP neurons. When they did so, and then exposed mice to sensory gamma stimulation, they found that there was no longer an increase in arterial pulsatility and there was no more gamma-stimulated amyloid clearance.

“We think that many neuropeptides are involved,” Murdock said. Tsai added that a major new direction for the lab’s research will be determining what other peptides or other molecular factors may be driven by sensory gamma stimulation.

Tsai and Murdock added that while this paper focuses on what is likely an important mechanism – glymphatic clearance of amyloid – by which sensory gamma stimulation helps the brain, it’s probably not the only underlying mechanism that matters. The clearance effects shown in this study occurred rather rapidly but in lab experiments and clinical studies weeks or months of chronic sensory gamma stimulation have been needed to have sustained effects on cognition.

With each new study, however, scientists learn more about how sensory stimulation of brain rhythms may help treat neurological disorders.

Source: Picower Institute at MIT

Categories : Regenerative MedicineTags :

Using Fat Tissue, Researchers 3D-Print Skin that Contains Hair Precursors

On By ModernMedia
AI art image created using Gencraft

Fat tissue holds the key to 3D printing layered living skin and potentially hair follicles, according to researchers who recently harnessed fat cells and supporting structures from clinically procured human tissue to precisely correct injuries in rats. The advancement could have implications for reconstructive facial surgery and even hair growth treatments for humans.

The team’s findings published in Bioactive Materials, and the team received a patent in February for the bioprinting technology it developed and used in this study.

“Reconstructive surgery to correct trauma to the face or head from injury or disease is usually imperfect, resulting in scarring or permanent hair loss,” said Ibrahim T. Ozbolat, professor of engineering science and mechanics, of biomedical engineering and of neurosurgery at Penn State, who led the international collaboration that conducted the work. “With this work, we demonstrate bioprinted, full thickness skin with the potential to grow hair in rats. That’s a step closer to being able to achieve more natural-looking and aesthetically pleasing head and face reconstruction in humans.”

While scientists have previously 3D bioprinted thin layers of skin, Ozbolat and his team are the first to intraoperatively print a full, living system of multiple skin layers, including the bottom-most layer or hypodermis. Intraoperatively refers to the ability to print the tissue during surgery, meaning the approach may be used to more immediately and seamlessly repair damaged skin, the researchers said. The top layer — the epidermis that serves as visible skin — forms with support from the middle layer on its own, so it doesn’t require printing. The hypodermis, made of connective tissue and fat, provides structure and support over the skull.

“The hypodermis is directly involved in the process by which stem cells become fat,” Ozbolat said. “This process is critical to several vital processes, including wound-healing. It also has a role in hair follicle cycling, specifically in facilitating hair growth.”

The researchers started with human adipose, or fat, tissue obtained from patients undergoing surgery at Penn State Health Milton S. Hershey Medical Center. Collaborator Dino J. Ravnic, associate professor of surgery in the Division of Plastic Surgery at Penn State College of Medicine, led his lab in obtaining the fat for extraction of the extracellular matrix to make one component of the bioink.

Ravnic’s team also obtained stem cells, which have the potential to mature into several different cell types if provided the correct environment, from the adipose tissue to make another bioink component. Each component was loaded into one of three compartments in the bioprinter. The third compartment was filled with a clotting solution that helps the other components properly bind onto the injured site.

“The three compartments allow us to co-print the matrix-fibrinogen mixture along with the stem cells with precise control,” Ozbolat said. “We printed directly into the injury site with the target of forming the hypodermis, which helps with wound healing, hair follicle generation, temperature regulation and more.”

They achieved both the hypodermis and dermis layers, with the epidermis forming within two weeks by itself.

“We conducted three sets of studies in rats to better understand the role of the adipose matrix, and we found the co-delivery of the matrix and stem cells was crucial to hypodermal formation,” Ozbolat said. “It doesn’t work effectively with just the cells or just the matrix – it has to be at the same time.”

They also found that the hypodermis contained downgrowths, the initial stage of early hair follicle formation. According to the researchers, while fat cells do not directly contribute to the cellular structure of hair follicles, they are involved in their regulation and maintenance.

“In our experiments, the fat cells may have altered the extracellular matrix to be more supportive for downgrowth formation,” Ozbolat said. “We are working to advance this, to mature the hair follicles with controlled density, directionality and growth.”

According to Ozbolat, the ability to precisely grow hair in injured or diseased sites of trauma can limit how natural reconstructive surgery may appear. He said that this work offers a “hopeful path forward,” especially in combination with other projects from his lab involving printing bone and investigating how to match pigmentation across a range of skin tones.

Source: Penn State

Categories : Cardiovascular Disease Lab Tests and ImagingTags :

A Better View of Atherosclerotic Plaques with New Imaging Technique

On By ModernMedia
Source: Wikimedia CC0

Researchers have developed a new catheter-based device that combines two powerful optical techniques to image atherosclerotic plaques that can build up inside the heart’s coronary arteries. By providing new details about plaque, the device could help clinicians and researchers improve treatments for preventing heart attacks and strokes.

“Atherosclerosis, leading to heart attacks and strokes, is the number one cause of death in Western societies – exceeding all combined cancer types – and, therefore, a major public health issue,” said research team member leader Laura Marcu from University of California, Davis. “Better clinical management made possible by advanced intravascular imaging tools will benefit patients by providing more accurate information to help cardiologists tailor treatment or by supporting the development of new therapies.”

In the Optica Publishing Group journal Biomedical Optics Express, researchers describe their new flexible device, which combines fluorescence lifetime imaging (FLIM) and polarisation-sensitive optical coherence tomography (PSOCT) to capture rich information about the composition, morphology and microstructure of atherosclerotic plaques. The work was a collaborative project with Brett Bouma and Martin Villiger, experts in OCT from the Wellman Center for Photomedicine at Massachusetts General Hospital.

“With further testing and development, our device could be used for longitudinal studies where intravascular imaging is obtained from the same patients at different timepoints, providing a picture of plaque evolution or response to therapeutic interventions,” said Julien Bec, first author of the paper. “This will be very valuable to better understand disease evolution, evaluate the efficacy of new drugs and treatments and guide stenting procedures used to restore normal blood flow.”

Gaining an unprecedented view

Most of what scientists know about how atherosclerosis forms and develops over time comes from histopathology studies of postmortem coronary specimens. Although the development of imaging systems such as intravascular ultrasound and intravascular OCT has made it possible to study plaques in living patients, there is still a need for improved methods and tools to investigate and characterise atherosclerosis.

To address this need, the researchers embarked on a multi-year research project to develop and validate multispectral FLIM as an intravascular imaging modality. FLIM can provide insights into features such as the composition of the extracellular matrix, the presence of inflammation and the degree of calcification inside an artery. In earlier work, they combined FLIM with intravascular ultrasound, and in this new work they combined it with PSOCT. PSOCT provides high-resolution morphological information along with birefringence and depolarisation measurements. When used together, FLIM and PSOCT provide an unprecedented amount of information on plaque morphology, microstructure and biochemical composition.

“Birefringence provides information about the plaque collagen, a key structural protein that helps with lesion stabilization, and depolarisation is related to lipid content that contributes to plaque destabilization,” said Bec. “Holistically, this hybrid approach can provide the most detailed picture of plaque characteristics of all intravascular imaging modalities reported to date.”

Getting two imaging modalities into one device

The development of multimodal intravascular imaging systems compatible with coronary catheterisation is technologically challenging. It requires flexible catheters < 1mm diameter that can operate in vessels with sharp twists and turns. A high imaging speed of around 100 frames/second is also necessary to limit cardiac motion artefacts and ensure proper imaging inside an artery.

To integrate FLIM and PSOCT into a single device without compromising the performance of either imaging modality, the researchers used optical components previously developed by Marcu’s lab and other research groups. Key to achieving high PSOCT performance was a newly designed rotary collimator with high light throughput and a high return loss, ie the ratio of power reflected back toward the light source compared to the power incident on the device. The catheter system they developed has similar dimensions and flexibility as the intravascular imaging devices that are currently in clinical use.

After testing the new system with artificial tissue to demonstrate basic functionality on well characterized samples, the researchers also showed that it could be used to measure properties of a healthy coronary artery removed from a pig. Finally, in vivo testing in swine hearts demonstrated that the hybrid catheter system’s performance was sufficient to support work toward clinical validation. These tests all showed that the FLIM-PSOCT catheter system could simultaneously acquire co-registered FLIM data over four distinct spectral bands and PSOCT backscattered intensity, birefringence and depolarization information.

Next, the researchers plan to use the intravascular imaging system to image plaques in ex vivo human coronary arteries. By comparing the optical signals acquired using the system with plaque characteristics identified by expert pathologists, they can better understand which features can be identified by FLIM-PSOCT and use this to develop prediction models. They also plan to move forward with testing in support of clinical validation of the system in patients.

Source: Optica

Categories : COVID Ethics and LawTags :

Pretoria High Court Judgement On COVID-19 Vaccinations

On By ModernMedia
Photo by Bill Oxford on Unsplash

On 05 January 2023, the COVID Care Alliance NPC and other applicants brought an urgent court application against the South African Health Products Regulatory Authority (SAHPRA), including the President of the Republic of South Africa and others to prevent people from being vaccinated.

The applicants wanted the court to order that all COVID-19 vaccines programs must be stopped and that all COVID-19 vaccination sections in healthcare facilities in South Africa must be closed, and the effective withdrawal from circulation of the vaccines. The applicants also sought an order interdicting the approval of vaccines for emergency authorisation or registration.

On 27 February 2024, the Pretoria High Court dismissed with costs an application filed by the applicants on the grounds that the applicants do not have the right to prevent others, who do not share in their beliefs or opinions, from being vaccinated.

SAHPRA submitted evidence to the Court to show that the applicants’ attempt to prevent government from using vaccines to address the COVID-19 pandemic was misguided, and the applicants heavily relied on hearsay and speculation, as well as supported their arguments with the opinion of persons who were not experts.

Source: SAHPRA

Categories : Expert Opinion Substance UseTags :

Proposed Update to Schedule 6 of the Medicines and Related Substances Act

On By ModernMedia
Photo by Kindel Media on Unsplash

By Rodney Africa, Partner, Adriano Esterhuizen, Partner & Daveraj Sauls, Associate at Webber Wentzel

The Minister of Health (the Minister) in terms of section 22A(2) of the Medicines and Related Substances Act 101 of 1965 (the Medicines Act), and on the recommendation of the South African Health Products Regulatory Authority, has invited interested persons to submit substantiated comments or representations on the proposed update of Schedule 6 to the Medicines Act.

The proposed update to Schedule 6 of the Medicines Act intends to exclude certain cannabis products containing Tetrahydrocannabinol (THC), the psychoactive compound in cannabis, from the operation of the Schedules to the Medicines Act and will, inter alia, permit the manufacturing of cannabis consumer items and products, with no limitation on the percentage of THC content, provided that the items and products have no pharmacological action or medicinal purpose. This will also allow adults to cultivate and possess cannabis in private for personal consumption, with no limitation on the percentage of THC content.

This proposed update appears to be a move away from utilising THC content as a threshold to distinguish between consumable and industrial cannabis. This shift seemingly comes in response to the growing South African market for cannabis products and aims to augment the Cannabis for Private Purposes Bill 2023 [B19 – 2020] recently passed by the National Council of Provinces and submitted to the President for his assent and signature.

Interested persons have until Thursday, 14 March 2024 to submit any substantiated comments or representations by emailing mihloti.mushwana@health.gov.za or paul.tsebe@health.gov.za.

Categories : Medical IndustryTags :

Ethics Webinar: Advertising Your Practice

On By ModernMedia

We are excited to extend a special invitation to you for our upcoming webinar on March 13th, titled “Advertising Your Practice.” Following the tremendous success of our previous webinars, we are thrilled to present this insightful session featuring industry experts JP Ellis, Claims & Legal expert at EthiQal, and Athol Gordon, Partner at Clyde & Co, renowned for their expertise in medical negligence.

This webinar will provide valuable insights into effectively advertising your practice, drawing from their extensive experience and expertise. Don’t miss this opportunity to gain valuable knowledge and network with other professionals in the field.

Date: March 13th

Time: 19h00 – 20h30

Location: Zoom (Online)

Please register here: https://webinar.ethiqal.co.za/  to secure your spot.

We look forward to your participation and insightful contributions during the Q&A session.

Categories : COVID VaccinesTags :

Hypervaccination: Researchers Investigate a Man who Received 217 COVID Shots

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Researchers in Germany find no negative effects on immune system

Photo by Gustavo Fring

Researchers at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen have examined a man who has received more than 200 vaccinations against COVID. They learned of his case via newspaper reports.

Until now, it has been unclear what effects hypervaccination such as this would have on the immune system. Some scientists were of the opinion that immune cells would become less effective after becoming used to the antigens. This proved not to be the case in the individual in question: his immune system is fully functional. Certain immune cells and antibodies against SARS-CoV-2 are even present in considerably higher concentrations than is the case with people who have only received three vaccinations. The results have been published in the journal Lancet Infectious Diseases.

More than 60 million people in Germany have been vaccinated against SARS-Coronavirus 2, the majority of them several times. The man who has now been examined by researchers at FAU claims to have received 217 vaccinations for private reasons. There is official confirmation for 134 of these vaccinations.

“We learned about his case via newspaper articles,” explains Privatdozent Dr Kilian Schober from the Institute of Microbiology – Clinical Microbiology, Immunology and Hygiene (director Prof Dr Christian Bogdan). “We then contacted him and invited him to undergo various tests in Erlangen. He was very interested in doing so.” Schober and his colleagues wanted to know what consequences hypervaccination such as this would have. How does it alter the immune response?

As a rule, vaccinations contain parts of the pathogen or a type of construction plan that the vaccinated person’s cells can use to produce these pathogenic components themselves. Thanks to these antigens, the immune system learns to recognize the real pathogen in the event of a later infection. It can then react more rapidly and forcibly. But what happens if the body’s immune system is exposed extremely often to a specific antigen?

“That may be the case in a chronic infection such as HIV or Hepatitis B, that has regular flare-ups,” explains Schober. “There is an indication that certain types of immune cells, known as T-cells, then become fatigued, leading to them releasing fewer pro-inflammatory messenger substances.” This and other effects triggered by the cells becoming used to the antigens can weaken the immune system. The immune system is then no longer able to combat the pathogen so effectively.

Blood samples from several years investigated

The current study, which also involved researchers from Munich and Vienna, does not deliver any indication that this is the case, however. “The individual has undergone various blood tests over recent years;” explains Schober. “He gave us his permission to assess the results of these analyses. In some cases, samples had been frozen, and we were able to investigate these ourselves. We were also able to take blood samples ourselves when the man received a further vaccination during the study at his own insistence. We were able to use these samples to determine exactly how the immune system reacts to the vaccination.”

The results showed that the individual has large numbers of T-effector cells against SARS-CoV-2. These act as the body’s own soldiers that fight against the virus. The test person even had more of these compared to the control group of people who have received three vaccinations. The researchers did not perceive any fatigue in these effector cells, they were similarly effective as those in the control group who had received the normal number of vaccinations.

Memory T cells are another aspect the researchers explored. These are cells at a preliminary stage, before effector cells. Similar to stem cells, these cells can replenish numbers of suitable effector cells. “The number of memory cells was just as high in our test case as in the control group,” explains Katharina Kocher, one of the leading authors of the study. “Over all, we did not find any indication for a weaker immune response, rather the contrary.”  In addition, even the 217th vaccination that the man received during the study still had an effect: the number of antibodies against SARS-CoV-2 increased significantly as a result.

Immune system remains active against other pathogens

Further tests indicated that there was no change to the immune system’s effectiveness against other pathogens. It therefore appears to be the case that the hypervaccination has not damaged the immune system as such. “Our test case was vaccinated with a total of eight different vaccines, including different available mRNA vaccines,” stated Dr Kilian Schober. “The observation that no noticeable side effects were triggered in spite of this extraordinary hypervaccination indicates that the drugs have a good degree of tolerability.”

However, this is one individual case. The results are not sufficient for making far-reaching conclusions let alone recommendations for the general public. “Current research indicates that a three dose vaccination, coupled with regular top-up vaccines for vulnerable groups, remains the favoured approach. There is no indication that more vaccines are required.”

Source: Friedrich–Alexander University Erlangen–Nurnberg

Categories : Neurology Substance UseTags :

Continued Cocaine Use Disrupts Communication between Major Brain Networks

On By ModernMedia
Photo by Colin Davis on Unsplash

A collaborative research endeavour by scientists in the Departments of Radiology, Neurology, and Psychology and Neuroscience at the UNC School of Medicine have demonstrated the deleterious effects of chronic cocaine use on the functional networks in the brain.

Their study titled “Network Connectivity Changes Following Long-Term Cocaine Use and Abstinence,” was highlighted by the editor of Journal of Neuroscience in “This Week in The Journal.” The findings show that continued cocaine use affects how crucial neural networks communicate with one another in the brain, including the default mode network (DMN), the salience network (SN), and the lateral cortical network (LCN).

“The disrupted communication between the DMN and SN can make it harder to focus, control impulses, or feel motivated without the drug,” said Li-Ming Hsu, PhD, assistant professor of radiology and lead author on the study. “Essentially, these changes can impact how well they respond to everyday situations, making recovery and resisting cravings more challenging.”

Hsu led this project during his postdoctoral tenure at the Center for Animal MRI in the Biomedical Research Imaging Center and the Department of Neurology. The work provides new insights into the brain processes that underlie cocaine addiction and creates opportunities for the development of therapeutic approaches and the identification of an imaging marker for cocaine use disorders.

The brain operates like an orchestra, where each instrumentalist has a special role crucial for creating a coherent piece of music. Specific parts of the brain need to work together to complete a task. The DMN is active during daydreams and reflections, the SN is crucial for attentiveness, and the CEN, much like a musical conductor, plays a role in our decision-making and problem-solving.

The research was motivated by observations from human functional brain imaging studies suggesting chronic cocaine use alters connectivity within and between the major brain networks. Researchers needed a longitudinal animal model to understand the relationship between brain connectivity and the development of cocaine dependence, as well as changes during abstinence.

Researchers employed a rat model to mimic human addiction patterns, allowing the models to self-dose by nose poke. Paired with advanced neuroimaging techniques, the behavioural approach enables a deeper understanding of the brain’s adaptation to prolonged drug use and highlights how addictive substances can alter the functioning of critical brain networks.

Hsu’s research team used functional MRI scans to explore the changes in brain network dynamics on models that self-administrated cocaine. Over a period of 10 days followed by abstinence, researchers observed significant alterations in network communication, particularly between the DMN and SN.

These changes were more pronounced with increased cocaine intake over the 10 days of self-administration, suggesting a potential target for reducing cocaine cravings and aiding those in recovery. The changes in these networks’ communication could also serve as useful imaging biomarkers for cocaine addiction.

The study also offered novel insights into the anterior insular cortex (AI) and retrosplenial cortex (RSC). The former is responsible for emotional and social processing; whereas, the latter controls episodic memory, navigation, and imagining future events. Researchers noted that there was a difference in coactivity between these two regions before and after cocaine intake. This circuit could be a potential target for modulating associated behavioural changes in cocaine use disorders.

“Prior studies have demonstrated functional connectivity changes with cocaine exposure; however, the detailed longitudinal analysis of specific brain network changes, especially between the anterior insular cortex (AI) and retrosplenial cortex (RSC), before and after cocaine self-administration, and following extended abstinence, provides new insights,” said Hsu.

Source: University of North Carolina Health Care

Categories : Metabolic Disorders PaediatricsTags :

Waist-to-height Ratio Superior to BMI for Detecting Fat Obesity in Children and Adolescents

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Photo by Andres Ayrton on Pexels

A simple measure of obesity in children and adolescents that could replace body mass index (BMI) has been identified in a new study as waist circumference-to-height ratio. This measure detected excess fat mass and distinguished fat mass from muscle mass in children and adolescents more accurately than BMI. The study was conducted in collaboration between the University of Bristol in the UK, the University of Exeter in the UK, and the University of Eastern Finland, and the results were published in Pediatric Research.

The prevalence of childhood and adolescent obesity has reached an epidemic proportion and is affecting nearly 1 in 4 children in the current decade.

Unfortunately, obesity in the young population has been associated with cardiovascular, metabolic, neurological, musculoskeletal diseases and premature death in adulthood.

Accurately detecting overweight and obesity in children is critical to initiating timely interventions.

For nearly a generation, weight-to-height ratio charts and BMI for age and sex have been used to diagnose children with obesity.

However, these surrogate assessment tools are inaccurate in childhood and adolescence since they do not distinguish fat mass from muscle mass.For instance, two children with similar BMI might have different proportions of fat and muscle mass which makes obesity diagnosis difficult.

Expensive tools such as the dual-energy Xray absorptiometry (DEXA) scan accurately measures fat and muscle content of the body, but this device is not readily available in primary health care centres.

Recently, the American Academy of Pediatrics (AAP) published a clinical guideline on childhood obesity and requested urgent research on inexpensive and accurate alternative measures of obesity.

Emerging studies in adults appear to suggest that waist circumference-to-height ratio predicts premature death better than BMI and could be a potential added tool to BMI measure in improving the diagnosis of obesity.

However, there has been no former evaluation of how much waist circumference-to-height ratio measurements agree with DEXA-measured fat mass and muscle mass during growth from childhood to young adulthood.

In addition, the threshold of waist circumference-to-height ratio needed to detect excess fat in children is not clear, hence this study.

The current study is the largest and the longest follow-up DEXA-measured fat mass and muscle mass study in the world using the University of Bristol’s Children of the 90s data (also known as the Avon Longitudinal Study of Parents and Children). The study included 7,237 children (51% females) aged 9 years who were followed-up until age 24 years.

Their BMI and waist circumference-to-height ratio were measured at ages 9, 11, 15, 17, and 24 years.

When different devices measure a variable with an exact resemblance, it is described as perfect agreement of the devices with a score of 100%. For example, two DEXA scans from different manufacturers would measure fat mass with a near-perfect agreement of 99 to 100%.

Waist circumference-to-height ratio had a very high agreement of 81 — 89% with DEXA-measured total body fat mass and trunk fat mass, but a low agreement with muscle mass (24 — 39%). BMI had a moderate agreement with total fat mass and trunk fat mass (65 — 72%) and muscle mass (52 — 58%). Since BMI had a moderate agreement with DEXA-measured muscle mass, it is difficult to specify whether BMI measures excess fat or muscle mass.

The optimal waist circumference-to-height ratio cut points that predicted the 95th percentile of total fat mass in males was 0.53 and 0.54 in females.

This cut point detected 8 out of 10 males and 7 out of 10 females who truly had excess DEXA-measured fat.

The cut point also identified 93 out of 100 males and 95 out of 100 females who truly do not have excess fat.

“This study provides novel information that would be useful in updating future childhood obesity guidelines and policy statements. The average waist circumference-to-height ratio in childhood, adolescence, and young adulthood is 0.45, it does not vary with age and among individuals like BMI. Waist circumference-to-height ratio might be preferable to BMI assessment in children and adolescent clinics as an inexpensive tool for detecting excess fat. Parents should not be discouraged by the BMI or weight of their children but can inexpensively confirm whether the weight is due to increase in excess fat by examining their kid’s waist circumference-to-height ratio,” says Andrew Agbaje, an award-winning physician and pediatric clinical epidemiologist at the University of Eastern Finland.

Source: University of Eastern Finland

Categories : Cardiovascular DiseaseTags :

Sweetened Drinks Linked to Higher Atrial Fibrillation Risk

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An analysis of UK Biokank data showed that adults who reported drinking two litres or more of sugar- or artificially sweetened drinks per week had a higher risk of atrial fibrillation compared with adults who drank fewer such beverages, according to new research published in Circulation: Arrhythmia and Electrophysiology, a peer-reviewed journal of the American Heart Association.

The study also found that drinking one litre or less per week of pure, unsweetened juice, such as orange or vegetable juice, was associated with a lower risk of atrial fibrillation (AFib). However, the study could not confirm whether the sweetened drinks caused AFib, yet the association remained after accounting for a person’s genetic susceptibility to the condition.

Consuming sweetened drinks has been linked to Type 2 diabetes and obesity in previous research. This large study of health data in the UK Biobank is among the first to assess a possible link between sugar- or artificially sweetened beverages and AFib.

“Our study’s findings cannot definitively conclude that one beverage poses more health risk than another due to the complexity of our diets and because some people may drink more than one type of beverage,” said lead study author Ningjian Wang, MD, PhD, a researcher at the Shanghai Ninth People’s Hospital and Shanghai Jiao Tong University School of Medicine in Shanghai, China. “However, based on these findings, we recommend that people reduce or even avoid artificially sweetened and sugar-sweetened beverages whenever possible. Do not take it for granted that drinking low-sugar and low-calorie artificially sweetened beverages is healthy, it may pose potential health risks.”

The researchers reviewed data from dietary questionnaires and genetic data for more than 200 000 adults free of AFib at the time they enrolled in the UK Biobank, between 2006 and 2010. During the nearly 10-year follow-up period, there were 9362 cases of AFib among the study participants.

The analysis found:Compared to people who did not consume any sweetened drinks, there was a 20% increased risk of atrial fibrillation among people who said they drank more than 2 litres per week of artificially sweetened beverages; and a 10% increased risk among participants who reported drinking 2 litres per week or more of sugar-sweetened beverages.

People reporting 1 litre or less of pure fruit juice each week had an 8% lower risk of atrial fibrillation.

Participants who consumed more artificially sweetened beverages were more likely to be female, younger, have a higher body mass index and a higher prevalence of Type 2 diabetes.

Participants who consumed more sugar-sweetened beverages were more likely to be male, younger, have a higher body mass index, a higher prevalence of heart disease and lower socioeconomic status.

Those who drank sugar-sweetened beverages and pure juice were more likely to have a higher intake of total sugar than those who drank artificially sweetened drinks.

Smoking may have also affected risk, with smokers who drank more than two litres per week of sugar-sweetened beverages having a 31% higher risk of AFib, whereas no significant increase risk was noted for former smokers or people who never smoked.

“These novel findings on the relationships among atrial fibrillation risk and sugar- and artificially sweetened beverages and pure juice may prompt the development of new prevention strategies by considering decreasing sweetened drinks to help improve heart health,” Wang said.

Researchers also evaluated whether a genetic susceptibility to AFib was a factor in the association with sweetened beverages. The analysis found the AFib risk was high with the consumption of more than 2 litres of artificially sweetened drinks per week regardless of genetic susceptibility.

Source: American Heart Association