Posts tagged diseases
Articles and news from the latest research reports.
The zebrafish is a major player in the study of vertebrate biology and human disease. Its transparent, externally fertilized eggs, short reproductive cycle and fast growth mean that its embryonic development can be studied closely while the animal is alive, and the fish is a useful model for studying gene behaviour and function.
Now, researchers led by Stephen Ekker, a molecular biologist at the Mayo Clinic in Rochester, Minnesota, have for the first time made custom changes to parts of the zebrafish (Danio rerio) genome, using artificial enzymes to cut portions of DNA out of targeted positions in a gene sequence, and replace them with synthetic DNA.
Researchers have long known that individual diseases are associated with genes in specific locations of the genome
Genetics researchers at the University of North Carolina at Chapel Hill now have shown definitively that a small number of places in the human genome are associated with a large number and variety of diseases. In particular, several diseases of aging are associated with a locus which is more famous for its role in preventing cancer.
For this analysis, researchers at UNC Lineberger Comprehensive Cancer Center catalogued results from several hundred human Genome-Wide Association Studies (GWAS) from the National Human Genome Research Institute. These results provided an unbiased means to determine if varied different diseases mapped to common ‘hotspot’ regions of the human genome. This analysis showed that two different genomic locations are associated with two major subcategories of human disease.
“Our team is interested in understanding genetic susceptibility to diseases associated with aging, including cancer,” said PhD student William Jeck, who was first author on the study, published in the journal Aging Cell.
Studying Everyday Eye Movements Could Aid in Diagnosis of Neurological Disorders
USC-led team has designed a low-cost, easily-deployed method for detecting ADHD, Parkinson’s, and Fetal Alcohol Spectrum Disorder
Researchers at the University of Southern California have devised a method for detecting certain neurological disorders through the study of eye movements.
In a study published today in the Journal of Neurology, researchers claim that because Attention Deficit Hyperactivity Disorder (ADHD), Fetal Alcohol Spectrum Disorder (FASD) and Parkinson’s Disease (PD) each involve ocular control and attention dysfunctions, they can be easily identified through an evaluation of how patients move their eyes while they watch television.
“Natural attention and eye movement behavior – like a drop of saliva – contains a biometric signature of an individual and her/his state of brain function or dysfunction,” the article states. “Such individual signatures, and especially potential biomarkers of particular neurological disorders which they may contain, however, have not yet been successfully decoded.”
Typical methods of detection—clinical evaluation, structured behavioral tasks and neuroimaging—are costly, labor-intensive and limited by a patient’s ability to understand and comply with instructions. To solve this problem, doctoral student Po-He Tseng and Professor Laurent Itti of the Department of Computer Science at the USC Viterbi School of Engineering, along with collaborators at Queen’s University in Canada, have devised a new screening method.
Participants in the study were simply instructed to “watch and enjoy” television clips for 20 minutes while their eye movements were recorded. Eye-tracking data was then combined with normative eye-tracking data and a computational model of visual attention to extract 224 quantitative features, allowing the team to use new machine learning techniques to identify critical features that differentiated patients from control subjects.
With eye movement data from 108 subjects, the team was able to identify older adults with Parkinson’s Disease with 89.6% accuracy, and children with either ADHD or FASD with 77.3% accuracy.
Providing new insights into which aspects of attention and gaze control are affected by specific disorders, the team’s method provides considerable promise as an easily-deployed, low-cost, high-throughput screening tool, especially for young children and elderly populations who may be less compliant to traditional tests.
“For the first time, we can actually decode a person’s neurological state from their everyday behavior, without having to subject them to difficult or time-consuming tests,” Itti said.
Lubricated nanoparticles penetrate the brain
Nanoparticles often meet a sticky end in the brain. In theory, the tiny structures could deliver therapeutic drugs to a brain tumour, but navigating the narrow, syrupy spaces between brain cells is difficult. A spot of lubrication could help.
Nanoparticles (green) coated with poly(ethylene-glycol) (PEG) (Image: Elizabeth Nance, Graeme Woodworth, Kurt Sailor)
Justin Hanes at Johns Hopkins University in Baltimore, Maryland, was surprised to discover just how impermeable brain tissue is to nanoparticles. “It’s very sticky stuff,” he says, similar in adhesiveness to mucus, which protects parts of the body – such as the respiratory system – by trapping foreign particles.
It was thought that the adhesiveness of brain tissue limited the size of particles that can smoothly spread through the brain. Signalling molecules, nutrients and waste products below 64 nanometres in diameter can pass through the tissue with relative ease, but larger nanoparticles – suitable for delivering a payload of drugs to a specific location in the brain – quickly get stuck.
Now Hanes and his colleagues have doubled that size limit. They coated their nanoparticles with a densely-packed polymer shield, which lubricates their surface by preventing electrostatic and hydrophobic interactions with the surrounding tissue. “A nice hydrated shell around the particle prevents it from adhering to cells,” says Hanes.
Tracking the particles
Using this approach, they were able to observe the diffusion of nanoparticles 114 nanometres in diameter through live mouse brains and dissected human and rat brain tissue. Hanes believes the true upper size limit now lies somewhere between 114 nm and 200 nm. “Things were starting to slow down at 114,” he says.
But further research is needed before the team can progress to clinical trials in humans. “At this scale, it is very important to understand where our nanoparticles go once injected into the body,” says team member Elizabeth Nance, also of Johns Hopkins University. “We will need to show that, when combined with a therapeutic agent, these particles are getting to our site of interest, are having the intended effect and are not causing any side effects or toxicity to healthy normal tissue.”
"The effect of this work should be long-term," says Paul Wilson at the University of Warwick in Coventry, UK. The result represents significant progress in the battle to administer drugs within the brain, he says. "More effective and longer-lasting treatments against brain diseases, such as tumours and strokes, will no doubt soon follow."
Source: NewScientist
For 25 years, the rhesus monkeys were kept semi-starved, lean and hungry. The males’ weights were so low they were the equivalent of a 6-foot-tall man who tipped the scales at just 120 to 133 pounds. The hope was that if the monkeys lived longer, healthier lives by eating a lot less, then maybe people, their evolutionary cousins, would, too. Some scientists, anticipating such benefits, began severely restricting their own diets.
The results of this major, long-awaited study, which began in 1987, are finally in. But it did not bring the vindication calorie restriction enthusiasts had anticipated. It turns out the skinny monkeys did not live any longer than those kept at more normal weights. Some lab test results improved, but only in monkeys put on the when they were old. The causes of death — , heart disease — were the same in both the underfed and the normally fed monkeys.
Zebrafish Study Explains Why the Circadian Rhythm Affects Your Health
The circadian rhythm is regulated by a “clock” that reacts to both incoming light and genetic factors.
In an article now being published in the scientific journal Cell Reports, it is demonstrated for the first time that disruption of the circadian rhythm immediately inhibit blood vessel growth in zebra fish embryos.
During experiments with hours-old zebra fish embryos, the researchers manipulated their circadian rhythm through exposing them to lighting conditions varying from constant darkness to constant light. The growth of blood vessels in the various groups was then studied. The results showed that exposure to constant light (1800 lux) markedly impaired blood vessel growth; additionally, it affected the expression of genes that regulate the circadian clock.
"The results can definitely be translated into clinical circumstances. Individuals with disrupted circadian rhythms — for example, shift workers who work under artificial lights at night, people with sleeping disorders or a genetic predisposition — should be on guard against illnesses associated with disrupted blood vessel growth," says Lasse Dahl Jensen, researcher in Cardiovascular Physiology at Linköping University (LiU), and lead writer of the article.
Such diseases include heart attack, stroke, chronic inflammation, and cancer. Disruptions in blood vessel growth can also affect fetal development, women’s reproductive cycles, and the healing of wounds.
The connections between the rising rates of chronic disease and the production and consumption of modern foods can no longer be ignored. Our food supply is not healthy, nor is it sustainable. It has changed so dramatically that we have yet to adapt to the changes. Our food supply has been completely adulterated over the past few decades alone, more drastically than during any other time in history.
Nervous System: Facts, Function & Diseases
The nervous system is a complex collection of nerves and specialized cells known as neurons that transmit signals between different parts of the body. Vertebrates — animals with backbones and spinal columns — have central and peripheral nervous systems.
The central nervous system is made up of the brain, spinal cord and retina. The peripheral nervous system consists of sensory neurons, ganglia (clusters of neurons) and nerves that connect to one another and to the central nervous system.
Credit: iDesign, Shutterstock
Description of the nervous system
The nervous system is essentially the body’s electrical wiring. It is composed of nerves, which are cylindrical bundles of fibers that start at the brain and central cord and branch out to every other part of the body.
Neurons send signals to other cells through thin fibers called axons, which cause chemicals known as neurotransmitters to be released at junctions called synapses. A synapse gives a command to the cell and the entire communication process typically takes only a fraction of a millisecond.
Sensory neurons react to physical stimuli such as light, sound and touch and send feedback to the central nervous system about the body’s surrounding environment. Motor neurons, located in the central nervous system or in peripheral ganglia, transmit signals to activate the muscles or glands.
Glial cells, derived from the Greek word for “glue,” support the neurons and hold them in place. Glial cells also feed nutrients to neurons, destroy pathogens, remove dead neurons and act as traffic cops by directing the axons of neurons to their targets. Specific types of glial cells (oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system) generate layers of a fatty substance called myelin that wraps around axons and provides electrical insulation to enable them to rapidly and efficiently transmit signals.
Most babies born in developed countries share a common painful experience — a heel prick that is done soon after birth. Blood from this is deposited onto a slip of paper, called a Guthrie card, which doctors use to screen for devastating and sometimes fatal diseases. A study published today in Genome Research suggests that these cards, which are sometimes stored for decades, could provide an early snapshot of an individual’s epigenome, the chemical changes that influence gene expression and are likely to have a role in heart disease, diabetes, cancer and other diseases.
The human microbiome: Me, myself, us
Looking at human beings as ecosystems that contain many collaborating and competing species could change the practice of medicine.
A human being is an individual who has grown from a fertilised egg which contained genes from both father and mother. A growing band of biologists, however, think this definition incomplete. They see people not just as individuals, but also as ecosystems. In their view, the descendant of the fertilised egg is merely one component of the system. The others are trillions of bacteria, each equally an individual, which are found in a person’s gut, his mouth, his scalp, his skin and all of the crevices and orifices that subtend from his body’s surface.
A healthy adult human harbours some 100 trillion bacteria in his gut alone. That is ten times as many bacterial cells as he has cells descended from the sperm and egg of his parents. These bugs, moreover, are diverse. Egg and sperm provide about 23,000 different genes. The microbiome, as the body’s commensal bacteria are collectively known, is reckoned to have around 3m. Admittedly, many of those millions are variations on common themes, but equally many are not, and even the number of those that are adds something to the body’s genetic mix.