Stem cells are an ongoing source of the differentiated cells that make up the tissues and organs of animals and plants. There is great interest in stem cells because they have potential in the development of therapies for replacing defective or damaged cells resulting from a variety of disorders and injuries, such as Parkinson disease, heart disease, and diabetes. There are two major types of stem cells: embryonic stem cells and adult stem cells, which are also called tissue stem cells.
Stem cell. (2020). In Encyclopædia Britannica.
If an experimental treatment existed for your illness - would you try it? Thousands of desperate Australians are turning to controversial, unproven stem cell treatments in the hope it cure a whole range of illnesses.
Parkinsonism, a group of chronic neurological disorders characterised by progressive loss of motor function resulting from the degeneration of neurons in the area of the brain that controls voluntary movement.
Parkinsonism was first described in 1817 by the British physician James Parkinson in his “Essay on the Shaking Palsy.” Various types of the disorder are recognised, but the disease described by Parkinson, called Parkinson disease, is the most common form.
Parkinsonism. (2020). In Encyclopædia Britannica.
Parkinson disease is also called primary parkinsonism, paralysis agitans, or idiopathic parkinsonism, meaning the disease has no identifiable cause. This distinguishes it from secondary parkinsonism, a group of disorders very similar in nature to Parkinson disease but that arise from known or identifiable causes. The onset of Parkinson disease typically occurs between the ages of 60 and 70, although it can occur before the age of 40. It is rarely inherited. Parkinson disease often begins with a slight tremor of the thumb and forefinger, sometimes called “pill-rolling,” and slowly progresses over 10 to 20 years, resulting in paralysis, dementia and death.
All types of parkinsonism are characterised by four main signs, including tremors of resting muscles, particularly of the hands; muscular rigidity of the arms, legs, and neck; difficulty in initiating movement (bradykinesia); and postural instability. A variety of other features may accompany these characteristics, including a lack of facial expression (known as “masked face”), difficulty in swallowing or speaking, loss of balance, a shuffling gait, depression, and dementia.
Parkinsonism. (2020). In Encyclopædia Britannica.
Diabetes mellitus, disorder of carbohydrate metabolism characterised by impaired ability of the body to produce or respond to insulin and thereby maintain proper levels of sugar (glucose) in the blood. Diabetes is a major cause of morbidity and mortality, though these outcomes are not due to the immediate effects of the disorder. They are instead related to the diseases that develop as a result of chronic diabetes mellitus. These include diseases of large blood vessels (macrovascular disease, including coronary heart disease and peripheral arterial disease) and small blood vessels (microvascular disease, including retinal and renal vascular disease), as well as diseases of the nerves.
Type 1 diabetes accounts for about 5 to 10 percent of cases of diabetes. Most cases of type 1 diabetes develop in children or adolescents, but about 20 percent of new patients are adults. Most patients present with symptoms of hyperglycemia, but some patients present with diabetic ketoacidosis, a clear indication that insulin secretion has significantly deteriorated.
Type 2 diabetes is far more common than type 1 diabetes, accounting for about 90 percent of all cases. The frequency of type 2 diabetes varies greatly within and between countries and is increasing throughout the world. Most patients with type 2 diabetes are adults, often older adults, but it can also occur in children and adolescents. There is a stronger genetic component to type 2 diabetes than to type 1 diabetes.
Diabetes mellitus. (2020). In Encyclopædia Britannica.
Insulin is a hormone secreted by beta cells, which are located within clusters of cells in the pancreas called the islets of Langerhans. Insulin’s role in the body is to trigger cells to take up glucose so that the cells can use this energy-yielding sugar. Patients with diabetes may have dysfunctional beta cells, resulting in decreased insulin secretion, or their muscle and adipose cells may be resistant to the effects of insulin, resulting in a decreased ability of these cells to take up and metabolize glucose. In both cases, the levels of glucose in the blood increase, causing hyperglycemia (high blood sugar). As glucose accumulates in the blood, excess levels of this sugar are excreted in the urine. Because of greater amounts of glucose in the urine, more water is excreted with it, causing an increase in urinary volume and frequency of urination as well as thirst.
The name diabetes mellitus refers to these symptoms: diabetes, from the Greek diabainein, meaning “to pass through,” describes the copious urination, and mellitus, from the Latin meaning “sweetened with honey,” refers to sugar in the urine.
Other symptoms of diabetes include itching, hunger, weight loss, and weakness.
Diabetes mellitus. (2020). In Encyclopædia Britannica.
Spinal cord injury, any of various conditions caused by damage to the tract of nerves that extends from the base of the brain through the canal of the spinal column. Spinal cord injury often has permanent consequences for the function of body parts below the site of injury, the extent of which depends on whether the injury is incomplete, leaving some degree of sensation and movement, or complete, resulting in paralysis.
Spinal cord injury. (2020). In Encyclopædia Britannica.
The most dramatic cause of spinal cord injury is acute trauma, such as from motor vehicle accidents, sports accidents, accidental falls, and violence (e.g., gunshot and stab wounds). However, chronic trauma, such as from herniated intervertebral disks or primary or secondary tumours, and injury sustained as a result of certain medical conditions, such as interrupted blood flow to the spinal cord from anterior spinal artery syndrome, can also severely compromise spinal cord function.
Spinal cord injuries typically are distinguished by the level of injury within the spinal column, whether it occurs at vertebrae in the cervical, thoracic, lumbar, or sacral region. Thus, cervical injuries can occur at levels C1–C8, thoracic injuries at levels T1–T12, lumbar injuries at L1–L5, and sacral injuries at S1–S5. Cervical spinal cord injuries typically result in quadriplegia (or tetraplegia), because they cause weakness or paralysis in the arms and legs. Thoracic, lumbar, and sacral spinal cord injuries may result in paraplegia (weakness or paralysis in the legs) and cause dysfunction of the bladder, bowel, and sexual organs.
Spinal cord injury. (2020). In Encyclopædia Britannica.