Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems.Body mass index (BMI), which compares weight and height, is used to define a person as overweight (pre-obese) when their BMI is between 25 kg/m2 and 30 kg/m2 and obese when it is greater than 30 kg/m2.
Obesity increases the likelihood of various diseases, particularly heart disease, type 2 diabetes, breathing difficulties during sleep, certain types of cancer, and osteoarthritis. Obesity is most commonly caused by a combination of excessive dietary calories, lack of physical activity, and genetic susceptibility, though a limited number of cases are due solely to genetics, endocrine disorders, medications or psychiatric illness. Little evidence supports the commonly expressed view that some obese people eat little yet gain weight due to a slow metabolism. On average obese people have greater energy expenditure than their thin counterparts due to the energy required to maintain an increased body mass.
The primary treatment for obesity is dieting and physical exercise. If this fails, anti-obesity drugs may be taken to reduce appetite or inhibit fat absorption. In severe cases, surgery is performed or an intragastric balloon is placed to reduce stomach volume and or bowel length, leading to earlier satiation and reduced ability to absorb nutrients from food.
Obesity is a leading preventable cause of death worldwide, with increasing prevalence in adults and children, and authorities view it as one of the most serious public health problems of the 21st century. Obesity is stigmatized in the modern Western world, though it has been perceived as a symbol of wealth and fertility at other times in history, and still is in many parts of Africa.
Friday, October 23, 2009
DNA
Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.
Chemically, DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands run in opposite directions to each other and are therefore anti-parallel. Attached to each sugar is one of four types of molecules called bases. It is the sequence of these four bases along the backbone that encodes information. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called transcription.
Within cells, DNA is organized into long structures called chromosomes. These chromosomes are duplicated before cells divide, in a process called DNA replication. Eukaryotic organisms (animals, plants, fungi, and protists) store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts.[1] In contrast, prokaryotes (bacteria and archaea) store their DNA only in the cytoplasm. Within the chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.
Chemically, DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands run in opposite directions to each other and are therefore anti-parallel. Attached to each sugar is one of four types of molecules called bases. It is the sequence of these four bases along the backbone that encodes information. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called transcription.
Within cells, DNA is organized into long structures called chromosomes. These chromosomes are duplicated before cells divide, in a process called DNA replication. Eukaryotic organisms (animals, plants, fungi, and protists) store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts.[1] In contrast, prokaryotes (bacteria and archaea) store their DNA only in the cytoplasm. Within the chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.
New discovery drug in Parkinson’s disease
New discovery drug in Parkinson’s disease
Researchers funded by the National Institutes of Health have turned simple baker's yeast into a virtual army of medicinal chemists capable of rapidly searching for drugs to treat Parkinson's disease. In a study published online today Nature Chemical Biology, the researchers showed that they can rescue yeast cells from toxic levels of a protein implicated in Parkinson's disease by stimulating the cells to make very small proteins called cyclic peptides. Two of the cyclic peptides had a protective effect on the yeast cells and on neurons in an animal model of Parkinson's disease.
Parkinson's disease attacks cells in a part of the brain responsible for motor control and coordination. As those neurons degenerate, the disease leads to progressive deterioration of motor function including involuntary shaking, slowed movement, stiffened muscles, and impaired balance. The neurons normally produce a chemical called dopamine. A synthetic precursor of dopamine called L-DOPA or drugs that mimic dopamine's action can provide symptomatic relief from Parkinson's disease. Unfortunately, these drugs lose much of their effectiveness in later stages of the disease, and there is currently no means to slow the disease's progressive course. Investigators have discovered that vulnerable brain cells in patients with Parkinson's disease accumulate a protein called alpha-synuclein. Moreover, genetic abnormalities in alpha-synuclein cause a rare familial form of the disease. When yeast cells are engineered to produce large amounts of human alpha-synuclein, patient will die.
Cyclic peptides are fragments of protein that connect end-to-end to form a circle. Although cyclic peptides are synthetic, they resemble structures that are found in natural proteins and protein-based drugs, including pain killers, antibiotics and immunosuppressants. Cyclic peptides that suppress alpha-synuclein toxicity could be candidate drugs for Parkinson's disease, or they could help researchers identify new drug targets for the disease.
A procedure involves exposing yeast cells to short snippets of DNA that the cells can absorb and use to make cyclic peptides. Then, he flips the genetic switch that causes the cells to produce toxic levels of alpha-synuclein. If the yeast make cyclic peptides that suppress alpha-synuclein toxicity, they live; if not, they die. This simple assay enables testing millions of cyclic peptides simultaneously in millions of yeast cells. The process is extremely rapid and much less expensive compared to other techniques used to screen large number of chemicals with an eye toward new drugs.
Researchers funded by the National Institutes of Health have turned simple baker's yeast into a virtual army of medicinal chemists capable of rapidly searching for drugs to treat Parkinson's disease. In a study published online today Nature Chemical Biology, the researchers showed that they can rescue yeast cells from toxic levels of a protein implicated in Parkinson's disease by stimulating the cells to make very small proteins called cyclic peptides. Two of the cyclic peptides had a protective effect on the yeast cells and on neurons in an animal model of Parkinson's disease.
Parkinson's disease attacks cells in a part of the brain responsible for motor control and coordination. As those neurons degenerate, the disease leads to progressive deterioration of motor function including involuntary shaking, slowed movement, stiffened muscles, and impaired balance. The neurons normally produce a chemical called dopamine. A synthetic precursor of dopamine called L-DOPA or drugs that mimic dopamine's action can provide symptomatic relief from Parkinson's disease. Unfortunately, these drugs lose much of their effectiveness in later stages of the disease, and there is currently no means to slow the disease's progressive course. Investigators have discovered that vulnerable brain cells in patients with Parkinson's disease accumulate a protein called alpha-synuclein. Moreover, genetic abnormalities in alpha-synuclein cause a rare familial form of the disease. When yeast cells are engineered to produce large amounts of human alpha-synuclein, patient will die.
Cyclic peptides are fragments of protein that connect end-to-end to form a circle. Although cyclic peptides are synthetic, they resemble structures that are found in natural proteins and protein-based drugs, including pain killers, antibiotics and immunosuppressants. Cyclic peptides that suppress alpha-synuclein toxicity could be candidate drugs for Parkinson's disease, or they could help researchers identify new drug targets for the disease.
A procedure involves exposing yeast cells to short snippets of DNA that the cells can absorb and use to make cyclic peptides. Then, he flips the genetic switch that causes the cells to produce toxic levels of alpha-synuclein. If the yeast make cyclic peptides that suppress alpha-synuclein toxicity, they live; if not, they die. This simple assay enables testing millions of cyclic peptides simultaneously in millions of yeast cells. The process is extremely rapid and much less expensive compared to other techniques used to screen large number of chemicals with an eye toward new drugs.
Sunday, July 19, 2009
Stress management
Prolonged psychological stress may negatively impact health, such as by weakening the immune system and mind. Stress management is the application of methods to either reduce stress or increase tolerance to stress. Relaxation techniques are physical methods used to relieve stress. Psychological methods include cognitive therapy, meditation, and positive thinking which work by reducing response to stress. Improving relevant skills and abilities builds confidence, which also reduces the stress reaction to situations where those skills are applicable.
Reducing uncertainty, by increasing knowledge and experience related to stress-causing situations, has the same effect. Learning to cope with problems better, such as improving problem solving and time management skills, may also reduce stressful reaction to problems. Repeatedly facing an object of one's fears may also desensitize the fight-or-flight response with respect to that stimulus—e.g., facing bullies may reduce fear of bullies.
Prolonged hours of surfing on the Internet is a major concern that can affect the eyes significantly. White backgrounds on computer screens with a viewing distance of less than 14 inches is known to increase strain, mental fatigue and temporary di-chromatic visions in a normal healthy human being. Trying to opt for black or any non-white backgrounds can help in reducing eye strain in front of PCs.
Prolonged psychological stress may negatively impact health, such as by weakening the immune system and mind. Stress management is the application of methods to either reduce stress or increase tolerance to stress. Relaxation techniques are physical methods used to relieve stress. Psychological methods include cognitive therapy, meditation, and positive thinking which work by reducing response to stress. Improving relevant skills and abilities builds confidence, which also reduces the stress reaction to situations where those skills are applicable.
Reducing uncertainty, by increasing knowledge and experience related to stress-causing situations, has the same effect. Learning to cope with problems better, such as improving problem solving and time management skills, may also reduce stressful reaction to problems. Repeatedly facing an object of one's fears may also desensitize the fight-or-flight response with respect to that stimulus—e.g., facing bullies may reduce fear of bullies.
Prolonged hours of surfing on the Internet is a major concern that can affect the eyes significantly. White backgrounds on computer screens with a viewing distance of less than 14 inches is known to increase strain, mental fatigue and temporary di-chromatic visions in a normal healthy human being. Trying to opt for black or any non-white backgrounds can help in reducing eye strain in front of PCs.
BIONANOSCIENCE
Bionanoscience is a field of research that has emerged at the interface of nanoscience and biology. Bionanoscience focuses on nanoscale phenomena in biological, biomicking and bioinspired materials and structures. It focuses on fundamental scientific research to advance nanoscience and nanotechnology as well as biology and medicine.
Material properties and applications studied in bionanoscience include mechanical properties(e.g. deformation, adhesion, failure), electrical/electronic (e.g. electromechanical stimulation, capacitors, energy storage/batteries), optical (e.g. absorption, luminescence, photochemistry), thermal (e.g. thermomutability, thermal management), biological (e.g. how cells interact with nanomaterials, molecular flaws/defects, biosensing, biological mechanisms s.a. mechanosensing), nanoscience of disease (e.g. genetic disease, cancer, organ/tissue failure), as well as computing (e.g. DNA computing). The impact of bionanoscience, achieved through structural and mechanistic analyses of biological processes at nanoscale, is their translation into synthetic and technological applications through nanotechnology.
This field relies on a variety of research methods, including experimental tools (e.g. imaging, characterization via AFM/optical tweezers etc., x-ray & diffraction based tools, synthesis via self-assembly, recombinant DNA methods, etc.), theory (e.g. statistical mechanics, nanomechanics, etc.), as well as computational approaches (bottom-up multi-scale simulation, supercomputing).
Bionanoscience is a field of research that has emerged at the interface of nanoscience and biology. Bionanoscience focuses on nanoscale phenomena in biological, biomicking and bioinspired materials and structures. It focuses on fundamental scientific research to advance nanoscience and nanotechnology as well as biology and medicine.
Material properties and applications studied in bionanoscience include mechanical properties(e.g. deformation, adhesion, failure), electrical/electronic (e.g. electromechanical stimulation, capacitors, energy storage/batteries), optical (e.g. absorption, luminescence, photochemistry), thermal (e.g. thermomutability, thermal management), biological (e.g. how cells interact with nanomaterials, molecular flaws/defects, biosensing, biological mechanisms s.a. mechanosensing), nanoscience of disease (e.g. genetic disease, cancer, organ/tissue failure), as well as computing (e.g. DNA computing). The impact of bionanoscience, achieved through structural and mechanistic analyses of biological processes at nanoscale, is their translation into synthetic and technological applications through nanotechnology.
This field relies on a variety of research methods, including experimental tools (e.g. imaging, characterization via AFM/optical tweezers etc., x-ray & diffraction based tools, synthesis via self-assembly, recombinant DNA methods, etc.), theory (e.g. statistical mechanics, nanomechanics, etc.), as well as computational approaches (bottom-up multi-scale simulation, supercomputing).
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