Medical Tourism – Blog

The brain is the most complex organ in the human body. It produces our every thought, action, memory, feeling and experience of the world. This jelly-like mass of tissue, weighing in at around 1.4 kilograms, contains a staggering one hundred billion nerve cells, or neurons. The complexity of the connectivity between these cells is mind-boggling. Each neuron can make contact with thousands or even tens of thousands of others, via tiny structures called synapses. Our brains form a million new connections for every second of our lives. The pattern and strength of the connections is constantly changing and no two brains are alike. It is in these changing connections that memories are stored, habits learned and personalities shaped, by reinforcing certain patterns of brain activity, and losing others.

Grey matter

While people often speak of their “grey matter”, the brain also contains white matter. The grey matter is the cell bodies of the neurons, while the white matter is the branching network of thread-like tendrils – called dendrites and axons - that spread out from the cell bodies to connect to other neurons. But the brain also has another, even more numerous type of cell, called glial cells. These outnumber neurons ten times over. Once thought to be support cells, they are now known to amplify neural signals and to be as important as neurons in mental calculations. There are many different types of neuron, only one of which is unique to humans and the other great apes, the so called spindle cells.

Brain structure is shaped partly by genes, but largely by experience. Only relatively recently it was discovered that new brain cells are being born throughout our lives – a process called neurogenesis. The brain has bursts of growth and then periods of consolidation, when excess connections are pruned. The most notable bursts are in the first two or three years of life, during puberty, and also a final burst in young adulthood. How a brain ages also depends on genes and lifestyle too. Exercising the brain and giving it the right diet can be just as important as it is for the rest of the body.

Chemical messengers

The neurons in our brains communicate in a variety of ways. Signals pass between them by the release and capture of neurotransmitter and neuromodulator chemicals, such as glutamate, dopamine, acetylcholine, noradrenalin, serotonin and endorphins. Some neurochemicals work in the synapse, passing specific messages from release sites to collection sites, called receptors. Others also spread their influence more widely, like a radio signal, making whole brain regions more or less sensitive.

These neurochemicals are so important that deficiencies in them are linked to certain diseases. For example, a loss of dopamine in the basal ganglia, which control movements, leads to Parkinson’s disease. It can also increase susceptibility to addiction because it mediates our sensations of reward and pleasure. Similarly, a deficiency in serotonin, used by regions involved in emotion, can be linked to depression or mood disorders, and the loss of acetylcholine in the cerebral cortex is characteristic of Alzheimer’s disease.

Brain scanning

Within individual neurons, signals are formed by electrochemical pulses. Collectively, this electrical activity can be detected outside the scalp by an electroencephalogram (EEG). These signals have wave-like patterns, which scientists classify from alpha (common while we are relaxing or sleeping), through to gamma (active thought). When this activity goes awry, it is called a seizure. Some researchers think that synchronizing the activity in different brain regions is important in perception.

Other ways of imaging brain activity are indirect. Functional magnetic resonance imaging (fMRI) or positron emission tomography (PET) monitors blood flow. MRI scans, computed tomography (CT) scans and diffusion tensor images (DTI) use the magnetic signatures of different tissues, X-ray absorption, or the movement of water molecules in those tissues, to image the brain. These scanning techniques have revealed which parts of the brain are associated with which functions. Examples include activity related to sensations, movement, libido, choices, regrets, motivations and even racism. However, some experts argue that we put too much trust in these results and that they raise privacy issues.

Before scanning techniques were common, researchers relied on patients with brain damage caused by strokes, head injuries or illnesses, to determine which brain areas are required for certain functions. This approach exposed the regions connected to emotions, dreams, memory, language and perception and to even more enigmatic events, such as religious or “paranormal” experiences. One famous example was the case of Phineas Gage, a 19th century railroad worker who lost part of the front of his brain when a 1-metre-long iron pole was blasted through his head during an explosion. He recovered physically, but was left with permanent changes to his personality, showing for the first time that specific brain regions are linked to different processes.

Structure in mind

The most obvious anatomical feature of our brains is the undulating surface of the cerebrum – the deep clefts are known as sulci and its folds are gyri. The cerebrum is the largest part of our brain and is largely made up of the two cerebral hemispheres. It is the most evolutionarily recent brain structure, dealing with more complex cognitive brain activities. It is often said that the right hemisphere is more creative and emotional and the left deals with logic, but the reality is more complex. Nonetheless, the sides do have some specializations, with the left dealing with speech and language, the right with spatial and body awareness.

Further anatomical divisions of the cerebral hemispheres are the occipital lobe at the back, devoted to vision, and the parietal lobe above that, dealing with movement, position, orientation and calculation. Behind the ears and temples lie the temporal lobes, dealing with sound and speech comprehension and some aspects of memory. And to the fore are the frontal and prefrontal lobes, often considered the most highly developed and most “human” of regions, dealing with the most complex thought, decision making, planning, conceptualizing, attention control and working memory. They also deal with complex social emotions such as regret, morality and empathy.

Another way to classify the regions is as sensory cortex and motor cortex, controlling incoming information, and outgoing behaviour respectively. Below the cerebral hemispheres, but still referred to as part of the forebrain, is the cingulate cortex, which deals with directing behaviour and pain. And beneath this lies the corpus callosum, which connects the two sides of the brain. Other important areas of the forebrain are the basal ganglia, responsible for movement, motivation and reward.

Urges and appetites

Beneath the forebrain lie more primitive brain regions. The limbic system, common to all mammals, deals with urges and appetites. Emotions are most closely linked with structures called the amygdala, caudate nucleus and putamen. Also in the limbic brain are the hippocampus - vital for forming new memories; the thalamus - a kind of sensory relay station; and the hypothalamus, which regulates bodily functions via hormone release from the pituitary gland. The back of the brain has a highly convoluted and folded swelling called the cerebellum, which stores patterns of movement, habits and repeated tasks – things we can do without thinking about them. The most primitive parts, the midbrain and brain stem, control the bodily functions we have no conscious control of, such as breathing, heart rate, blood pressure, sleep patterns, and so on. They also control signals that pass between the brain and the rest of the body, through the spinal cord.

Though we have discovered an enormous amount about the brain, huge and crucial remain. One of the most important is how does the brain produces our conscious experiences? The vast majority of the brain’s activity is subconscious. But our conscious thoughts, sensations and perceptions – what define us as humans – cannot yet be explained in terms of brain activity.

The benefits of human genetic engineering can be found in the headlines nearly every day. With the successful cloning of mammals and the completion of the Human Genome Project, scientists all over the world are aggressively researching the many different facets of human genetic engineering. These continuing breakthroughs have allowed science to more deeply understand DNA and its role in medicine, pharmacology, reproductive technology, and countless other fields.

The most promising benefit of human genetic engineering is gene therapy. Gene therapy is the medical treatment of a disease by repairing or replacing defective genes or introducing therapeutic genes to fight the disease. Over the past ten years, certain autoimmune diseases and heart disease have been treated with gene therapy. Many diseases, such as Huntington’s disease, ALS (Lou Gehrig’s disease), and cystic fibrosis are caused by a defective gene. The hope is that soon, through genetic engineering, a cure can be found for these diseases by either inserting a corrected gene, modifying the defective gene, or even performing genetic surgery. Eventually the hope is to completely eliminate certain genetic diseases as well as treat non-genetic diseases with an appropriate gene therapy.

Currently, many pregnant women elect to have their fetuses screened for genetic defects. The results of these screenings can allow the parents and their physician to prepare for the arrival of a child who may have special needs before, during, and after delivery. One possible future benefit of human genetic engineering is that, with gene therapy, a fetus genetic defect could be treated and even cured before it is born. There is also current research into gene therapy for embryos before they are implanted into the mother through in-vitro fertilization.

Another benefit of genetic engineering is the creation pharmaceutical products that are superior to their predecessors. These new pharmaceuticals are created through cloning certain genes. Currently on the market are bio-engineered insulin (which was previously obtained from sheep or cows) and human growth hormone (which in the past was obtained from cadavers) as well as bio-engineered hormones and blood clotting factors. The hope in the future is to be able to create plants or fruits that contain a certain drug by manipulating their genes in the laboratory.

The field of human genetic engineering is growing and changing at a tremendous pace. With these changes come several benefits and risks. These benefits and risks must be weighed in light of their moral, spiritual, legal, and ethical perspectives. The potential power of human genetic engineering comes with great responsibility.

Genetics , a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the process of inheritance, only began with the work of Gregor Mendel in the mid-nineteenth century. Although he did not know the physical basis for heredity, Mendel observed that organisms inherit traits via discrete units of inheritance, which are now called genes.

Genes correspond to regions within DNA, a molecule composed of a chain of four different types of nucleotides—the sequence of these nucleotides is the genetic information organisms inherit. DNA naturally occurs in a double stranded form, with nucleotides on each strand complementary to each other. Each strand can act as a template for creating a new partner strand—this is the physical method for making copies of genes that can be inherited.

The sequence of nucleotides in a gene is translated by cells to produce a chain of amino acids, creating proteins—the order of amino acids in a protein corresponds to the order of nucleotides in the gene. This relationship between nucleotide sequence and amino acid sequence is known as the genetic code. The amino acids in a protein determine how it folds into a three-dimensional shape; this structure is, in turn, responsible for the protein’s function. Proteins carry out almost all the functions needed for cells to live. A change to the DNA in a gene can change a protein’s amino acids, changing its shape and function: this can have a dramatic effect in the cell and on the organism as a whole.

Although genetics plays a large role in the appearance and behavior of organisms, it is the combination of genetics with what an organism experiences that determines the ultimate outcome. For example, while genes play a role in determining an organism’s size, the nutrition and other conditions it experiences after inception also have a large effect.

Although the science of genetics began with the applied and theoretical work of Gregor Mendel in the mid-1800s, other theories of inheritance preceded Mendel. A popular theory during Mendel’s time was the concept of blending inheritance: the idea that individuals inherit a smooth blend of traits from their parents. Mendel’s work disproved this, showing that traits are composed of combinations of distinct genes rather than a continuous blend. Another theory that had some support at that time was the inheritance of acquired characteristics: the belief that individuals inherit traits strengthened by their parents. This theory is now known to be wrong—the experiences of individuals do not affect the genes they pass to their children. Other theories included the pangenesis of Charles Darwin and Francis Galton’s reformulation of pangenesis as both particulate and inherited.

The modern science of genetics traces its roots to Gregor Johann Mendel, a German-Czech Augustinian monk and scientist who studied the nature of inheritance in plants. In his paper “Experiments on Plant Hybridization”, presented in 1865 to the Society for Research in Nature in Brünn, Mendel traced the inheritance patterns of certain traits in pea plants and described them mathematically. Although this pattern of inheritance could only be observed for a few traits, Mendel’s work suggested that heredity was particulate, not acquired, and that the inheritance patterns of many traits could be explained through simple rules and ratios.

The importance of Mendel’s work did not gain wide understanding until the 1890s, after his death, when other scientists working on similar problems re-discovered his research. William Bateson, a proponent of Mendel’s work, coined the word ”genetics” in 1905. Bateson popularized the usage of the word ”genetics” to describe the study of inheritance in his inaugural address to the Third International Conference on Plant Hybridization inLondon,England, in 1906.

After the rediscovery of Mendel’s work, scientists tried to determine which molecules in the cell were responsible for inheritance. In 1910, Thomas Hunt Morgan argued that genes are on chromosomes, based on observations of a sex-linked white eye mutation in fruit flies. In 1913, his student Alfred Sturtevant used the phenomenon of genetic linkage to show that genes are arranged linearly on the chromosome.

Although genes were known to exist on chromosomes, chromosomes are composed of both protein and DNA—scientists did not know which of these is responsible for inheritance. In 1928, Frederick Griffith discovered the phenomenon of transformation; dead bacteria could transfer genetic material to “transform” other still-living bacteria. Sixteen years later, in 1944, Oswald Theodore Avery, Colin McLeod and Maclyn McCarty identified the molecule responsible for transformation as DNA. The Hershey-Chase experiment in 1952 also showed that DNA is the genetic material of the viruses that infect bacteria, providing further evidence that DNA is the molecule responsible for inheritance.

James D. Watson and Francis Crick determined the structure of DNA in 1953, using the X-ray crystallography work of Rosalind Franklin and Maurice Wilkins that indicated DNA had a helical structure. Their double-helix model had two strands of DNA with the nucleotides pointing inward, each matching a complementary nucleotide on the other strand to form what looks like rungs on a twisted ladder. This structure showed that genetic information exists in the sequence of nucleotides on each strand of DNA. The structure also suggested a simple method for duplication: if the strands are separated, new partner strands can be reconstructed for each based on the sequence of the old strand.

Although the structure of DNA showed how inheritance works, it was still not known how DNA influences the behavior of cells. In the following years, scientists tried to understand how DNA controls the process of protein production. It was discovered that the cell uses DNA as a template to create matching messenger RNA, a molecule with nucleotides, very similar to DNA. The nucleotide sequence of a messenger RNA is used to create an amino acid sequence in protein; this translation between nucleotide and amino acid sequences is known as the genetic code.

With this molecular understanding of inheritance, an explosion of research became possible. One important development was chain-termination DNA sequencing in 1977 by Frederick Sanger: This technology allows scientists to read the nucleotide sequence of a DNA molecule. In 1983, Kary Banks Mullis developed the polymerase chain reaction, providing a quick way to isolate and amplify a specific section of a DNA from a mixture. Through the pooled efforts of the Human Genome Project and the parallel private effort by Celera Genomics, these and other techniques culminated in the sequencing of the human genome in 2003. This property was first observed by Gregor Mendel, who studied the segregation of heritable traits in pea plants. In his experiments studying the trait for flower color, Mendel observed that the flowers of each pea plant were either purple or white and never an intermediate between the two colors. These different, discrete versions of the same gene are called alleles.

In the case of pea, which is a diploid species, each individual plant has two alleles of each gene, one allele inherited from each parent. When a pair of organisms reproduce sexually, their offspring randomly inherit one of the two alleles from each parent. These observations of discrete inheritance and the segregation of alleles are collectively known as Mendel’s first law or the Law of Segregation.

Chronic lymphocytic leukemia (CLL) is a type of cancer of the blood and bone marrow — the spongy tissue inside bones where blood cells are made. The term “chronic” in chronic lymphocytic leukemia comes from the fact that it typically progresses more slowly than other types of leukemia. The term “lymphocytic” in chronic lymphocytic leukemia comes from the cells affected by the disease — a group of white blood cells called lymphocytes, which help the body fight infection.

Chronic lymphocytic leukemia most commonly affects older adults. Chronic lymphocytic leukemia treatments can help control the disease. Many people with chronic lymphocytic leukemia have no symptoms. Those who do develop signs and symptoms may experience:

1. Enlarged, but painless, lymph nodes
2. Fatigue
3. Fever
4. Pain in the upper left portion of the abdomen, which may be caused by an enlarged spleen
5. Night sweats
6. Weight loss
7. Frequent infections

Doctors aren’t certain what starts the process that causes chronic lymphocytic leukemia. Doctors know that something happens in order to cause a genetic mutation in the DNA of blood-producing cells. This mutation causes the blood cells to produce abnormal, ineffective lymphocytes — one type of white blood cell that helps the body fight infection. Beyond being ineffective, these abnormal lymphocytes continue to live and multiply, when normal lymphocytes would die. The abnormal lymphocytes accumulate in the blood and certain organs, where they cause complications. They may crowd healthy cells out of the bone marrow and interfere with normal blood cell production.

Doctors and researchers are working to understand the exact mechanism that causes chronic lymphocytic leukemia. Factors that may increase the risk of chronic lymphocytic leukemia include:

1. The age. Most people diagnosed with chronic lymphocytic leukemia are over 60.
2. The sex. Men are more likely than are women to develop chronic lymphocytic leukemia.
3. The race. Whites are more likely to develop chronic lymphocytic leukemia than are people of other races.
4. Family history of blood and bone marrow cancers. A family history of chronic lymphocytic leukemia or other blood and bone marrow cancers may increase the risk.
5. Exposure to chemicals. Certain herbicides and insecticides, including Agent Orange used during the Vietnam War, have been linked to an increased risk of chronic lymphocytic leukemia.

Blood tests
Tests and procedures used to diagnose chronic lymphocytic leukemia include blood tests designed to:

1. Count the number of cells in a blood sample. A complete blood count may be used to count the number of lymphocytes in a blood sample. A high number of B cells, one type of lymphocyte, may indicate chronic lymphocytic leukemia.
2. Determine the type of lymphocytes involved. A test called flow cytometry or immunophenotyping helps determine whether an increased number of lymphocytes is due to chronic lymphocytic leukemia, a different blood disorder or the body’s reaction to another process, such as infection. If chronic lymphocytic leukemia is present, flow cytometry may also help analyze the leukemia cells for characteristics that help predict how aggressive the cells are.
3. Analyze lymphocytes for genetic abnormalities. A test called fluorescence in situ hybridization (FISH) examines the chromosomes inside the abnormal lymphocytes to look for abnormalities. Doctors sometimes use this information to determine the prognosis and help choose a treatment.

Other tests
In some cases the doctor may order additional tests and procedures to aid in diagnosis, such as:

1. Bone marrow biopsy and aspiration
2. Computerized tomography

Staging
Once a diagnosis is confirmed, the doctor determines the extent (stage) of the chronic lymphocytic leukemia. Two different staging systems are used. Each assigns a stage — early, intermediate or advanced — that indicates the progression of a person’s chronic lymphocytic leukemia. These levels are used to determine the treatment options.

In general, people with early-stage disease don’t require immediate treatment. Those with intermediate-stage disease and advanced-stage disease may be given the option to begin treatment right away.

The treatment options for chronic lymphocytic leukemia depend on several factors, such as the stage of the cancer, whether you’re experiencing signs and symptoms, the overall health, and the preferences.

Treatment may not be necessary in early stages
People with early-stage chronic lymphocytic leukemia typically don’t receive treatment, though clinical trials are evaluating whether early treatment may be helpful. Studies have shown that early treatment doesn’t extend lives for people with early-stage chronic lymphocytic leukemia. Rather than put you through the potential side effects and complications of treatment before you need it, doctors carefully monitor the condition and reserve treatment for when the leukemia progresses. Doctors call this watchful waiting. The doctor will plan a checkup schedule for you. You may meet with the doctor and have the blood tested every few months to monitor the condition.

Treatments for intermediate and advanced stages 
If the doctor determines the chronic lymphocytic leukemia is progressing or is in the intermediate or advanced stages, the treatment options may include:

1. Chemotherapy. Chemotherapy is a drug treatment that kills cancer cells. Chemotherapy treatments can be given through a vein in the arm or taken in pill form. Depending on the situation, the doctor may use a single chemotherapy drug or you may receive a combination of drugs. Side effects depend on what chemotherapy drugs are used. Common side effects include fatigue, low blood cell counts and a risk of frequent infections.
2. Targeted drug therapy. Targeted drugs are designed to take advantage of the specific vulnerabilities of the cancer cells. Chronic lymphocytic leukemia cells have a variety of proteins on their surfaces. Targeted therapy drugs are designed to bind to a specific protein as a way to target and kill leukemia cells. Targeted therapy drugs used in treating chronic lymphocytic leukemia include rituximab (Rituxan), alemtuzumab (Campath) and ofatumumab (Arzerra). Side effects of these drugs include fever, chills and infections.
3. Bone marrow stem cell transplant. Bone marrow stem cell transplants use strong chemotherapy drugs to kill the stem cells in the bone marrow that are creating diseased lymphocytes. Then healthy adult blood stem cells from a donor are infused into the blood, where they travel to the bone marrow and begin making healthy blood cells. A reduced intensity, or “mini,” bone marrow stem cell transplant is similar to a standard stem cell transplant, but it uses lower doses of chemotherapy drugs. Bone marrow stem cells may be a treatment option for people who aren’t helped by other treatments or for certain people with very aggressive chronic lymphocytic leukemia.

The term cerebral palsy refers to any one of a number of neurological disorders that appear in infancy or early childhood and permanently affect body movement and muscle coordination but don’t worsen over time. Even though cerebral palsy affects muscle movement, it isn’t caused by problems in the muscles or nerves. It is caused by abnormalities in parts of the brain that control muscle movements. The majority of children with cerebral palsy are born with it, although it may not be detected until months or years later. The early signs of cerebral palsy usually appear before a child reaches 3 years of age. The most common are a lack of muscle coordination when performing voluntary movements (ataxia); stiff or tight muscles and exaggerated reflexes (spasticity); walking with one foot or leg dragging; walking on the toes, a crouched gait, or a “scissored” gait; and muscle tone that is either too stiff or too floppy. A small number of children have cerebral palsy as the result of brain damage in the first few months or years of life, brain infections such as bacterial meningitis or viral encephalitis, or head injury from a motor vehicle accident, a fall, or child abuse.

All types of Cerebral Palsy (CP) are characterized by abnormal muscle tone (i.e. slouching over while sitting), reflexes, or motor development and coordination. There can be joint and bone deformities and contractures (permanently fixed, tight muscles and joints). The classical symptoms are spasticities, spasms, other involuntary movements (e.g. facial gestures), unsteady gait, problems with balance, and/or soft tissue findings consisting largely of decreased muscle mass. Scissor walking (where the knees come in and cross) and toe walking (which can contribute to a gait reminiscent of a marionette) are common among people with CP who are able to walk, but taken on the whole, CP symptomatology is very diverse. The effects of cerebral palsy fall on a continuum of motor dysfunction which may range from slight clumsiness at the mild end of the spectrum to impairments so severe that they render coordinated movement virtually impossible at the other end the spectrum. Babies born with severe CP often have an irregular posture; their bodies may be either very floppy or very stiff. Birth defects, such as spinal curvature, a small jawbone, or a small head sometimes occur along with CP. Symptoms may appear or change as a child gets older. Some babies born with CP do not show obvious signs right away. Classically, CP becomes evident when the baby reaches the developmental stage at 6/12 to 9/12 months and is starting to mobilise, where preferential use of limbs, asymmetry or gross motor developmental delay is seen.

Secondary conditions can include seizures, epilepsy, apraxia, dysarthria or other communication disorders, eating problems, sensory impairments, mental retardation, learning disabilities, and/or behavioral disorders. Speech and language disorders are common in people with Cerebral Palsy. The incidence of dysarthria is estimated to range from 31% to 88%. Speech problems are associated with poor respiratory control, laryngeal and velopharyngeal dysfunction as well as oral articulation disorders that are due to restricted movement in the oral-facial muscles. There are three major types of dysarthria in cerebral palsy: spastic, dyskinetic (athetosis) and ataxic. Speech impairments in spastic dysarthria involves four major abnormalities of voluntary movement: spasticity, weakness, limited range of motion and slowness of movement. Speech mechanism impairment in athetosis involves a disorder in the regulation of breathing patterns, laryngeal dysfunction (monopitch, low, weak and breathy voice quality). It is also associated with articulatory dysfunction (large range of jaw movements), inappropriate positioning of the tongue, instability of velar elevation. Athetoid dysarthria is caused by disruption of the internal sensorimotor feedback system for appropriate motor comands, which leads to the generation of faulty movements that are perceived by others as involuntary. Ataxic dysarthria is uncommon in cerebral palsy. The speech characteristics are: imprecise consonants, irregular articulatory breakdown, distorted vowels, excess and equal stress, prolonged phonemes, slow rate, monopitch, monoloudness and harsh voice. Overall language delay is associated with problems of mental retardation, hearing impairment and learned helplessness Research conducted during the 1980s by the National Institute of Neurological Disorders and Stroke (NINDS) suggested that only a small number of cases of CP are caused by lack of oxygen during birth.

There is no cure for Cerebral Palsy (CP), but various forms of therapy can help a person with the disorder to function and live more effectively. In general, the earlier treatment begins the better chance children have of overcoming developmental disabilities or learning new ways to accomplish the tasks that challenge them. The earliest proven intervention occurs during the infant’s recovery in the neonatal intensive care unit (NICU). Treatment may include one or more of the following: physical therapy; occupational therapy; speech therapy; drugs to control seizures, alleviate pain, or relax muscle spasms (e.g. benzodiazepienes, baclofen and intrathecal phenol/baclofen); hyperbaric oxygen; the use of Botox to relax contracting muscles; surgery to correct anatomical abnormalities or release tight muscles; braces and other orthotic devices; rolling walkers; and communication aids such as computers with attached voice synthesizers. For instance, the use of a standing frame can help reduce spasticity and improve range of motion for people with CP who use wheelchairs. Nevertheless, there is only some benefit from therapy. Treatment is usually symptomatic and focuses on helping the person to develop as many motor skills as possible or to learn how to compensate for the lack of them. Non-speaking people with CP are often successful availing themselves of augmentative and alternative communication systems such as Blissymbols.

The immune system is composed of many interdependent cell types that collectively protect the body from bacterial, parasitic, fungal, viral infections and from the growth of tumor cells. Many of these cell types have specialized functions. The cells of the immune system can engulf bacteria, kill parasites or tumor cells, or kill viral-infected cells. Often, these cells depend on the T helper subset for activation signals in the form of secretions formally known as cytokines, lymphokines, or more specifically interleukins. The purpose of this article is to review the organs, cell types and interactions between cells of the immune system as a commentary on their importance and interdependence on the T helper subset. Such an understanding may help comprehend the root of immune deficiencies, and perceive potential avenues that the immune system can be modulated in the case of specific diseases.

 The Organs of the Immune System

Bone Marrow –

All the cells of the immune system are initially derived from the bone marrow. They form through a process called hematopoiesis. During hematopoiesis, bone marrow-derived stem cells differentiate into either mature cells of the immune system or into precursors of cells that migrate out of the bone marrow to continue their maturation elsewhere. The bone marrow produces B cells, natural killer cells, granulocytes and immature thymocytes, in addition to red blood cells and platelets.

Thymus – The function of the thymus is to produce mature T cells. Immature thymocytes, also known as prothymocytes, leave the bone marrow and migrate into the thymus. Through a remarkable maturation process sometimes referred to as thymic education, T cells that are beneficial to the immune system are spared, while those T cells that might evoke a detrimental autoimmune response are eliminated. The mature T cells are then released into the bloodstream.

Spleen – The spleen is an immunologic filter of the blood. It is made up of B cells, T cells, macrophages, dendritic cells, natural killer cells and red blood cells. In addition to capturing foreign materials (antigens) from the blood that passes through the spleen, migratory macrophages and dendritic cells bring antigens to the spleen via the bloodstream. An immune response is initiated when the macrophage or dendritic cells present the antigen to the appropriate B or T cells. This organ can be thought of as an immunological conference center. In the spleen, B cells become activated and produce large amounts of antibody. Also, old red blood cells are destroyed in the spleen.

Lymph Nodes – The lymph nodes function as an immunologic filter for the bodily fluid known as lymph. Lymph nodes are found throughout the body. Composed mostly of T cells, B cells, dendritic cells and macrophages, the nodes drain fluid from most of our tissues. Antigens are filtered out of the lymph in the lymph node before returning the lymph to the circulation. In a similar fashion as the spleen, the macrophages and dendritic cells that capture antigens present these foreign materials to T and B cells, consequently initiating an immune response.

 The Cells of the Immune System

T-Cells –

T lymphocytes are usually divided into two major subsets that are functionally and phenotypically (identifiably) different. The T helper subset, also called the CD4+ T cell, is a pertinent coordinator of immune regulation. The main function of the T helper cell is to augment or potentiate immune responses by the secretion of specialized factors that activate other white blood cells to fight off infection.

Another important type of T cell is called the T killer/suppressor subset or CD8+ T cell. These cells are important in directly killing certain tumor cells, viral-infected cells and sometimes parasites. The CD8+ T cells are also important in down-regulation of immune responses. Both types of T cells can be found throughout the body. They often depend on the secondary lymphoid organs (the lymph nodes and spleen) as sites where activation occurs, but they are also found in other tissues of the body, most conspicuously the liver, lung, blood, and intestinal and reproductive tracts.

Natural Killer Cells – Natural killer cells, often referred to as NK cells, are similar to the killer T cell subset (CD8+ T cells). They function as effector cells that directly kill certain tumors such as melanomas, lymphomas and viral-infected cells, most notably herpes and cytomegalovirus-infected cells. NK cells, unlike the CD8+ (killer) T cells, kill their targets without a prior “conference” in the lymphoid organs. However, NK cells that have been activated by secretions from CD4+ T cells will kill their tumor or viral-infected targets more effectively.

B Cells – The major function of B lymphocytes is the production of antibodies in response to foreign proteins of bacteria, viruses, and tumor cells. Antibodies are specialized proteins that specifically recognize and bind to one particular protein that specifically recognize and bind to one particular protein. Antibody production and binding to a foreign substance or antigen, often is critical as a means of signaling other cells to engulf, kill or remove that substance from the body.

Granulocytes or Polymorphonuclear (PMN) Leukocytes – Another group of white blood cells is collectively referred to as granulocytes or polymorphonuclear leukocytes (PMNs). Granulocytes are composed of three cell types identified as neutrophils, eosinophils and basophils, based on their staining characteristics with certain dyes. These cells are predominantly important in the removal of bacteria and parasites from the body. They engulf these foreign bodies and degrade them using their powerful enzymes.

Macrophages – Macrophages are important in the regulation of immune responses. They are often referred to as scavengers or antigen-presenting cells (APC) because they pick up and ingest foreign materials and present these antigens to other cells of the immune system such as T cells and B cells. This is one of the important first steps in the initiation of an immune response. Stimulated macrophages exhibit increased levels of phagocytosis and are also secretory.

Dendritic Cells – Another cell type, addressed only recently, is the dendritic cell. Dendritic cells, which also originate in the bone marrow, function as antigen presenting cells (APC). In fact, the dendritic cells are more efficient apcs than macrophages. These cells are usually found in the structural compartment of the lymphoid organs such as the thymus, lymph nodes and spleen. However, they are also found in the bloodstream and other tissues of the body. It is believed that they capture antigen or bring it to the lymphoid organs where an immune response is initiated. Unfortunately, one reason we know so little about dendritic cells is that they are extremely hard to isolate, which is often a prerequisite for the study of the functional qualities of specific cell types. Of particular issue here is the recent finding that dendritic cells bind high amount of HIV, and may be a reservoir of virus that is transmitted to CD4+ T cells during an activation event.

 The Immune Response

An immune response to foreign antigen requires the presence of an antigen-presenting cell (APC), (usually either a macrophage or dendritic cell) in combination with a B cell or T cell. When an APC presents an antigen on its cell surface to a B cell, the B cell is signalled to proliferate and produce antibodies that specifically bind to that antigen. If the antibodies bind to antigens on bacteria or parasites it acts as a signal for pmns or macrophages to engulf (phagocytose) and kill them. Another important function of antibodies is to initiate the “complement destruction cascade.” When antibodies bind to cells or bacteria, serum proteins called complement bind to the immobilized antibodies and destroy the bacteria by creating holes in them. Antibodies can also signal natural killer cells and macrophages to kill viral or bacterial-infected cells.

If the APC presents the antigen to T cells, the T cells become activated. Activated T cells proliferate and become secretory in the case of CD4+ T cells, or, if they are CD8+ T cells, they become activated to kill target cells that specifically express the antigen presented by the APC. The production of antibodies and the activity of CD8+ killer T cells are highly regulated by the CD4+ helper T cell subset. The CD4+ T cells provide growth factors or signals to these cells that signal them to proliferate and function more efficiently. This multitude of interleukins or cytokines that are produced and secreted by CD4+ T cells are often crucial to ensure the activation of natural killer cells, macrophages, CD8+ T cells etc.

Necrotizing fasciitis is an infection caused by bacteria. It can destroy skin, fat, and the tissue covering the muscles within a very short time. The disease sometimes is called flesh-eating bacteria. When it occurs on the genitals, it is called Fournier gangrene. “Flesh-eating bacteria” is a misnomer, as the bacteria do not actually “eat” the tissue. They cause the destruction of skin and muscle by releasing toxins (virulence factors), which include streptococcal pyogenic exotoxins. S. pyogenes produces an exotoxin known as a super antigen. This toxin is capable of activating T-cells non-specifically, which causes the overproduction of cytokines and severe systemic illness (Toxic shock syndrome).

Necrotizing fasciitis is very rare but serious. About 1 out of 4 people who get this infection die from it. Many people who get necrotizing fasciitis are in good health before they get the infection.
Your risk of getting this infection is higher if you:
1.Have a weak immune system.
2.Have chronic health problems such as diabetes, cancer, or liver or kidney disease.
3.Have cuts in your skin, including surgical wounds.
4.Recently had chickenpox or other viral infections that cause a rash.
5.Use steroid medicines, which can lower the body’s resistance to infection.
Causes of necrotizing fasciitis
Necrotizing fasciitis is caused by several kinds of bacteria. Some of these bacteria also cause infections such as strep throat and impetigo. Usually the infections caused by these bacteria are mild. But in rare cases they can cause a more dangerous infection.

You can get necrotizing fasciitis when bacteria enter a wound, such as from an insect bite, a burn, or a cut. You can also get it in:
1.Wounds that come in contact with ocean water, raw saltwater fish, or raw oysters. You also can get it through injuries from handling sea animals such as crabs.
2.An intestinal surgery site, or in tumors or gunshot injuries in the intestines.
3.A muscle strain or bruise, even if there is no break in the skin.
Bacteria that cause necrotizing fasciitis can be passed from person to person through close contact, such as kissing, or by touching the wound of the infected person. But a person who gets infected by the bacteria is unlikely to get necrotizing fasciitis unless he or she has an open wound, chickenpox, or an impaired immune system.

Symptoms
The symptoms often start suddenly after an injury. You may need medical care right away if you have pain that gets better over 24 to 36 hours and then suddenly gets worse. The pain may be much worse than you would expect from the size of the wound or injury. You may also have:
1.Skin that is red, swollen, and hot to the touch.
2.A fever and chills.
3.Nausea and vomiting.
4.Diarrhea.
The infection may spread rapidly. It quickly can become life-threatening. You may go into shock and have damage to skin, fat, and the tissue covering the muscles. This damage is called gangrene. Necrotizing fasciitis can lead to organ failure and death.
Diagnosis
The doctor will diagnose your infection based on how suddenly your symptoms started and how quickly the infection is spreading. The infected tissue may be tested for bacteria. You also may need X-rays, a CT scan, or an MRI to look for injury to your organs or to find out how much the infection has spread.
Treatment
Early treatment of necrotizing fasciitis is critical. The sooner treatment begins, the more likely you will recover from the infection and avoid serious complications, such as limb amputation or death. You may be treated in the intensive care unit (ICU) at the hospital.

Treatment may include:
1. Surgery that removes infected tissue and fluids to stop the spread of infection. Surgery is almost always needed. Most people need several surgeries to control the infection. Removing limbs (amputation) or organs may be done to save the person’s life, depending on how severe the infection is and where it has spread.
2. Medicines (such as antibiotics). These kill the bacteria causing the infection.
3. Procedures to treat complications such as shock, breathing problems, and organ failure.
4. Hyperbaric oxygen therapy. This can help prevent tissue death and promote healing.
Precaution
Necrotizing fasciitis is very rare. Bacteria that cause the disease usually don’t cause infection unless they enter the body through a cut or other break in the skin.
If you have been in close contact with someone who has necrotizing fasciitis, your doctor may give you an antibiotic to help reduce your chances of getting the infection. If you develop any symptoms of infection (such as pain, swelling, redness, or fever) after you’ve been in close contact with someone who has it, see your doctor right away.
To help prevent any kind of infection, wash your hands often, and always keep cuts, scrapes, burns, sores, and bites clean.

When you get on the weighing scale in the morning, you may be hoping that it registers a smaller number than the day before — you may be hoping that you’ve lost weight. It’s the quantity of mass in you, plus the force of gravity, that determines your weight. But what determines your mass?

That’s one of the most-asked, most-hotly pursued questions in physics today. Many of the experiments circulating in the world’s particle accelerators are looking into the mechanism that gives rise to mass. Scientists at CERN, as well as at Fermilab in Illinois, are hoping to find what they call the “Higgs boson.” Higgs, they believe, is a particle, or set of particles, that might give others mass.

The idea of one particle giving another mass is a bit counter-intuitive. Isn’t mass an inherent characteristic of matter? If not, how can one entity impart mass on all the others by simply floating by and interacting with them?

An oft-cited analogy describes it well: Imagine you’re at a Hollywood party. The crowd is rather thick, and evenly distributed around the room, chatting. When the big star arrives, the people nearest the door gather around her. As she moves through the party, she attracts the people closest to her, and those she moves away from return to their other conversations. By gathering a fawning cluster of people around her, she’s gained momentum, an indication of mass. She’s harder to slow down than she would be without the crowd. Once she’s stopped, it’s harder to get her going again.

This clustering effect is the Higgs mechanism, postulated by British physicist Peter Higgs in the 1960s. The theory hypothesizes that a sort of lattice, referred to as the Higgs field, fills the universe. This is something like an electromagnetic field, in that it affects the particles that move through it, but it is also related to the physics of solid materials. Scientists know that when an electron passes through a positively charged crystal lattice of atoms (a solid), the electron’s mass can increase as much as 40 times. The same might be true in the Higgs field: a particle moving through it creates a little bit of distortion — like the crowd around the star at the party — and that lends mass to the particle.

The question of mass has been an especially puzzling one, and has left the Higgs boson as the single missing piece of the Standard Model yet to be spotted. The Standard Model describes three of nature’s four forces: electromagnetism and the strong and weak nuclear forces. Electromagnetism has been fairly well understood for many decades. Recently, physicists have learned much more about the strong force, which binds the elements of atomic nuclei together, and the weak force, which governs radioactivity and hydrogen fusion (which generates the sun’s energy).

Electromagnetism describes how particles interact with photons, tiny packets of electromagnetic radiation. In a similar way, the weak force describes how two other entities, the W and Z particles, interact with electrons, quarks, neutrinos and others. There is one very important difference between these two interactions: photons have no mass, while the masses of W and Z are huge. In fact, they are some of the most massive particles known.

The first inclination is to assume that W and Z simply exist and interact with other elemental particles. But for mathematical reasons, the giant masses of W and Z raise inconsistencies in the Standard Model. To address this, physicists postulate that there must be at least one other particle — the Higgs boson.

The simplest theories predict only one boson, but others say there might be several. In fact, the search for the Higgs particle(s) is some of the most exciting research happening, because it could lead to completely new discoveries in particle physics. Some theorists say it could bring to light entirely new types of strong interactions, and others believe research will reveal a new fundamental physical symmetry called “supersymmetry.”

First, though, scientists want to determine whether the Higgs boson exists. The search has been on for over ten years, both at CERN’s Large Electron Positron Collider (LEP) in Geneva and at Fermilab in Illinois. To look for the particle, researchers must smash other particles together at very high speeds. If the energy from that collision is high enough, it is converted into smaller bits of matter — particles — one of which could be a Higgs boson. The Higgs will only last for a small fraction of a second, and then decay into other particles. So in order to tell whether the Higgs appeared in the collision, researchers look for evidence of what it would have decayed into.

In August 2000, physicists working at CERN’s LEP saw traces of particles that might fit the right pattern, but the evidence is still inconclusive. LEP was closed down in the beginning of November, 2000, but the search continues at Fermilab in Illinois, and will pick up again at CERN when the LHC (Large Hadron Collider) begins experiments in 2005.

It’s normal to worry and feel tense or scared when under pressure or facing a stressful situation. Anxiety is the body’s natural response to danger, an automatic alarm that goes off when you feel threatened. In moderation, anxiety isn’t always a bad thing. In fact, anxiety can help you stay alert and focused, spur you to action, and motivate you to solve problems. But when anxiety is constant or overwhelming, when it interferes with your relationships and activities, it stops being functional—that’s when you’ve crossed the line from normal, productive anxiety into the territory of anxiety disorders.

Because anxiety disorders are a group of related conditions rather than a single disorder, they can look very different from person to person. One individual may suffer from intense anxiety attacks that strike without warning, while another gets panicky at the thought of mingling at a party. Someone else may struggle with a disabling fear of driving, or uncontrollable, intrusive thoughts. Yet another may live in a constant state of tension, worrying about anything and everything. Despite their different forms, all anxiety disorders share one major symptom: persistent or severe fear or worry in situations where most people wouldn’t feel threatened.

In addition to the primary symptoms of irrational and excessive fear and worry, other common emotional symptoms of anxiety include:

Anxiety is more than just a feeling. As a product of the body’s fight-or-flight response, anxiety involves a wide range of physical symptoms. Because of the numerous physical symptoms, anxiety sufferers often mistake their disorder for a medical illness. They may visit many doctors and make numerous trips to the hospital before their anxiety disorder is discovered.

Common physical symptoms of anxiety include:

Not everyone who worries a lot has an anxiety disorder. You may be anxious because of an overly demanding schedule, lack of exercise or sleep, pressure at home or work, or even from too much coffee.

The bottom line is that if your lifestyle is unhealthy and stressful, you’re more likely to feel anxious—whether or not you have an anxiety disorder. So if you feel like you worry too much, take some time to evaluate how well you’re caring for yourself.

1. Do you make time each day for relaxation and fun?
2. Are you getting the emotional support you need?
3. Are you taking care of your body?
4. Are you overloaded with responsibilities?
5. Do you ask for help when you need it?

If your stress levels are through the roof, think about how you can bring your life back into balance. There may be responsibilities you can give up, turn down, or delegate to others. If you’re feeling isolated or unsupported, find someone you trust to confide in. Just talking about your worries can make them seem less frightening.

Self-help for anxiety attacks and anxiety disorders:

1. Write down your worries. Keep a pad and pencil on you, or type on a laptop, smartphone, or tablet. When you experience anxiety, write down your worries. Writing down is harder work than simply thinking them, so your negative thoughts are likely to disappear sooner.
2. Create an anxiety worry period. Choose one or two 10 minute “worry periods” each day, time you can devote to anxiety. During your worry period, focus only on negative, anxious thoughts without trying to correct them. The rest of the day, however, is to be designated free of anxiety. When anxious thoughts come into your head during the day, write them down and “postpone” them to your worry period.
3. Accept uncertainty. Unfortunately, worrying about all the things that could go wrong doesn’t make life any more predictable—it only keeps you from enjoying the good things happening in the present. Learn to accept uncertainty and not require immediate solutions to life’s problems.
4. Practice relaxation techniques. When practiced regularly, relaxation techniques such as mindfulness meditation, progressive muscle relaxation, and deep breathing can reduce anxiety symptoms and increase feelings of relaxation and emotional well-being.
5. Adopt healthy eating habits. Start the day right with breakfast, and continue with frequent small meals throughout the day. Going too long without eating leads to low blood sugar, which can make you feel more anxious.
6. Reduce alcohol and nicotine. They lead to more anxiety, not less.
7. Exercise regularly. Exercise is a natural stress buster and anxiety reliever. To achieve the maximum benefit, aim for at least 30 minutes of aerobic exercise on most days.
8. Get enough sleep. A lack of sleep can exacerbate anxious thoughts and feelings, so try to get 7 to 9 hours of quality sleep a night.

Behavioral therapy for anxiety disorders

Cognitive-behavioral therapy and exposure therapy are types of behavioral therapy, meaning they focus on behavior rather than on underlying psychological conflicts or issues from the past. Behavioral therapy for anxiety usually takes between 5 and 20 weekly sessions.

1. Cognitive-behavior therapy focuses on thoughts—or cognitions—in addition to behaviors. In anxiety disorder treatment, cognitive-behavioral therapy helps you identify and challenge the negative thinking patterns and irrational beliefs that fuel your anxiety.
2. Exposure therapy for anxiety disorder treatment encourages you to confront your fears in a safe, controlled environment. Through repeated exposures to the feared object or situation, either in your imagination or in reality, you gain a greater sense of control. As you face your fear without being harmed, your anxiety gradually diminishes.

A variety of medications, including benzodiazepines and antidepressants, are used in the treatment of anxiety disorders. But medication is most effective when combined with behavioral therapy and anxiety self-help strategies. Medication may sometimes be used in the short-term to relieve severe anxiety symptoms so that other forms of therapy can be pursued.

An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves. As a result, antioxidants are often reducing agents such as thiols, ascorbic acid or polyphenols. In addition to these uses of natural antioxidants in medicine, these compounds have many industrial uses, such as preservatives in food and cosmetics and preventing the degradation of rubber and gasoline.

The term antioxidant originally was used to refer specifically to a chemical that prevented the consumption of oxygen. In the late 19th and early 20th century, extensive study was devoted to the uses of antioxidants in important industrial processes, such as the prevention of metal corrosion, the vulcanization of rubber, and the polymerization of fuels in the fouling of internal combustion engines. Early research on the role of antioxidants in biology focused on their use in preventing the oxidation of unsaturated fats, which is the cause of rancidity. Antioxidant activity could be measured simply by placing the fat in a closed container with oxygen and measuring the rate of oxygen consumption. However, it was the identification of vitamins A, C, and E as antioxidants that revolutionized the field and led to the realization of the importance of antioxidants in the biochemistry of living organisms.

The possible mechanisms of action of antioxidants were first explored when it was recognized that a substance with anti-oxidative activity is likely to be one that is itself readily oxidized. Research into how vitamin E prevents the process of lipid peroxidation led to the identification of antioxidants as reducing agents that prevent oxidative reactions, often by scavenging reactive oxygen species before they can damage cells.

Antioxidants are found in varying amounts in foods such as vegetables, fruits, grain cereals, eggs, meat, legumes and nuts. Some antioxidants such as lycopene and ascorbic acid can be destroyed by long-term storage or prolonged cooking. Other antioxidant compounds are more stable, such as the polyphenolic antioxidants in foods such as whole-wheat cereals and tea. The effects of cooking and food processing are complex, as these processes can also increase the bioavailability of antioxidants, such as some carotenoids in vegetables. In general, processed foods contain fewer antioxidants than fresh and uncooked foods, since the preparation processes may expose the food to oxygen.