Top videos
Pathologic changes in chronic obstructive pulmonary disease (COPD) occur in the large (central) airways, the small (peripheral) bronchioles, and the lung parenchyma. Most cases of COPD are the result of exposure to noxious stimuli, most often cigarette smoke. The normal inflammatory response is amplified in persons prone to COPD development. The pathogenic mechanisms are not clear but are most likely diverse. Increased numbers of activated polymorphonuclear leukocytes and macrophages release elastases in a manner that cannot be counteracted effectively by antiproteases, resulting in lung destruction. The primary offender has been found to be human leukocyte elastase, with synergistic roles suggested for proteinase-3 and macrophage-derived matrix metalloproteinases (MMPs), cysteine proteinases, and a plasminogen activator. Additionally, increased oxidative stress caused by free radicals in cigarette smoke, the oxidants released by phagocytes, and polymorphonuclear leukocytes all may lead to apoptosis or necrosis of exposed cells. Accelerated aging and autoimmune mechanisms have also been proposed as having roles in the pathogenesis of COPD.[5, 6] Cigarette smoke causes neutrophil influx, which is required for the secretion of MMPs; this suggests, therefore, that neutrophils and macrophages are required for the development of emphysema. Studies have also shown that in addition to macrophages, T lymphocytes, particularly CD8+, play an important role in the pathogenesis of smoking-induced airflow limitation. To support the inflammation hypothesis further, a stepwise increase in alveolar inflammation has been found in surgical specimens from patients without COPD versus patients with mild or severe emphysema. Indeed, mounting evidence supports the concept that dysregulation of apoptosis and defective clearance of apoptotic cells by macrophages play a prominent role in airway inflammation, particularly in emphysema.[7] Azithromycin (Zithromax) has been shown to improve this macrophage clearance function, providing a possible future treatment modality.[8] In patients with stable COPD without known cardiovascular disease, there is a high prevalence of microalbuminuria, which is associated with hypoxemia independent of other risk factors.[9] Chronic bronchitis Mucous gland hyperplasia (as seen in the images below) is the histologic hallmark of chronic bronchitis. Airway structural changes include atrophy, focal squamous metaplasia, ciliary abnormalities, variable amounts of airway smooth muscle hyperplasia, inflammation, and bronchial wall thickening.
The term subclavian steal describes retrograde blood flow in the vertebral artery associated with proximal ipsilateral subclavian artery stenosis or occlusion, usually in the setting of subclavian artery occlusion or stenosis proximal to the origin of the vertebral artery. Alternatively, innominate artery disease has also been associated with retrograde flow in the ipsilateral vertebral artery, particularly where the subclavian artery origin is involved. Subclavian steal is frequently asymptomatic and may be discovered incidentally on ultrasound or angiographic examination for other indications, or it may be prompted by a clinical examination finding of reduced unilateral upper limb pulse or blood pressure. In some cases, patients may develop upper limb ischemic symptoms due to reduced arterial flow in the setting of subclavian artery occlusion, or they may develop neurologic symptoms due to posterior circulation ischemia associated with exercise of the ipsilateral arm.[1] Treatment has traditionally consisted of open subclavian artery revascularization, typically via carotid-subclavian bypass or subclavian artery transposition, which are generally durable procedures. Newer, less invasive options include endovascular intervention with recanalization as appropriate and angioplasty and stenting if required. The clinical relevance of subclavian steal was described in 1961 by Reivich, Holling and Roberts; however, the recognition of retrograde vertebral artery flow dates back another 100 years to Harrison and Smyth. Some papers, including a previous version of this article, advocate restricting the term subclavian steal to patients with neurologic symptoms only, but this is incorrect in view of the substantial literature using this term to describe the hemodynamic scenario of retrograde vertebral flow and proximal subclavian artery disease.
Guillain-Barre syndrome is a rare disorder in which your body's immune system attacks your nerves. Weakness and tingling in your extremities are usually the first symptoms. These sensations can quickly spread, eventually paralyzing your whole body. In its most severe form Guillain-Barre syndrome is a medical emergency. Most people with the condition must be hospitalized to receive treatment. The exact cause of Guillain-Barre syndrome is unknown. But it is often preceded by an infectious illness such as a respiratory infection or the stomach flu. There's no known cure for Guillain-Barre syndrome, but several treatments can ease symptoms and reduce the duration of the illness. Most people recover from Guillain-Barre syndrome, though some may experience lingering effects from it, such as weakness, numbness or fatigue.
Multiple sclerosis (MS) affects the brain and spinal cord. Early MS symptoms include weakness, tingling, numbness, and blurred vision. Other signs are muscle stiffness, thinking problems, and urinary problems. Treatment can relieve MS symptoms and delay disease progression.
Sickle cell anemia is an inherited form of anemia — a condition in which there aren't enough healthy red blood cells to carry adequate oxygen throughout your body. Normally, your red blood cells are flexible and round, moving easily through your blood vessels. In sickle cell anemia, the red blood cells become rigid and sticky and are shaped like sickles or crescent moons. These irregularly shaped cells can get stuck in small blood vessels, which can slow or block blood flow and oxygen to parts of the body. There's no cure for most people with sickle cell anemia. However, treatments can relieve pain and help prevent further problems associated with sickle cell anemia.
Hypothyroidism is a condition in which the body lacks sufficient thyroid hormone. Since the main purpose of thyroid hormone is to "run the body's metabolism," it is understandable that people with this condition will have symptoms associated with a slow metabolism. The estimates vary, but approximately 10 million Americans have this common medical condition. In fact, as many as 10% of women may have some degree of thyroid hormone deficiency. Hypothyroidism is more common than you would believe, and millions of people are currently hypothyroid and don't know it.
The bones, ligaments and tendons that make up your shoulder joint are encased in a capsule of connective tissue. Frozen shoulder occurs when this capsule thickens and tightens around the shoulder joint, restricting its movement. Doctors aren't sure why this happens to some people, although it's more likely to occur in people who have diabetes or those who recently had to immobilize their shoulder for a long period, such as after surgery or an arm fracture.