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Tonsillitis is inflammation of the tonsils, two oval-shaped pads of tissue at the back of the throat — one tonsil on each side. Signs and symptoms of tonsillitis include swollen tonsils, sore throat, difficulty swallowing and tender lymph nodes on the sides of the neck. Most cases of tonsillitis are caused by infection with a common virus, but bacterial infections also may cause tonsillitis. Because appropriate treatment for tonsillitis depends on the cause, it's important to get a prompt and accurate diagnosis. Surgery to remove tonsils, once a common procedure to treat tonsillitis, is usually performed only when bacterial tonsillitis occurs frequently, doesn't respond to other treatments or causes serious complications.
Mother-to-child transmission of HIV is the spread of HIV from an HIV-infected woman to her child during pregnancy, childbirth (also called labor and delivery), or breastfeeding (through breast milk). Mother-to-child transmission of HIV is also called perinatal transmission of HIV.
The complex circuitry interconnecting different areas in the brain, known collectively as white matter, is composed of millions of axons organized into fascicles and bundles. Upon macroscopic examination of sections of the brain, it is difficult to discern the orientation of the fibers. The same is true for conventional imaging modalities. However, recent advancements in magnetic resonance imaging (MRI) make such task possible in a live subject. By sensitizing an otherwise typical MRI sequence to the diffusion of water molecules it is possible to measure their diffusion coefficient in a given direction1. Normally, the axonal membrane and myelin sheaths pose barriers to the movement of water molecules and, thus, they diffuse preferentially along the axon2. Therefore, the direction of white matter bundles can be elucidated by determining the principal diffusivity of water. The three-dimensional representation of the diffusion coefficient can be given by a tensor and its mathematical decomposition provides the direction of the tracts3; this MRI technique is known as diffusion tensor imaging (DTI). By connecting the information acquired with DTI, three-dimensional depictions of white matter fascicles are obtained4. The virtual dissection of white matter bundles is rapidly becoming a valuable tool in clinical research.
Our journey begins with a transverse section of tightly packed axons as seen through light microscopy. Although represented as a two-dimensional "slice", we see that these axons in fact resemble tubes. A simulation of water molecules diffusing randomly inside the axons demonstrates how the membranes and myelin hinder their movement across them and shows the preferred diffusion direction --along the axons. The tracts depicted through DTI slowly blend in and we ride along with them. As we zoom out even more, we realize that it is a portion of the corpus callosum connecting the two sides of the brain we were traveling on and the great difference in relative scale of the individual axons becomes evident. The surface of the brain is then shown, as well as the rest of the white matter bundles--a big, apparently chaotic tangle of wires. Finally, the skin covers the brain.
With the exception of the simulated water molecules, all the data presented in the animation is obtained through microscopy and MRI. Computer algorithms for the extraction of the cerebral structures and a custom-built graphics engine make our journey through the brain's anatomy possible in a living person.
Micrograph courtesy of Dr. Christian Beaulieu, University of Alberta.
Music by Mario Mattioli.
References:
1. Stejskal, E.O., et al., J. Chem. Phys., 1965. 42:
2. Beaulieu, C., NMR Biomed., 2002. 15:435-55.
3. Basser, P.J., et al., J. Magn. Reson. B, 1994. 103:247-54.
4. Mori, S., et al., NMR Biomed., 2002. 15:468-80.
There are 3 major parts of the respiratory system: the airway, the lungs, and the muscles of respiration. The airway, which includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles, carries air between the lungs and the body's exterior.
Menstruation is a woman's monthly bleeding. When you menstruate, your body sheds the lining of the uterus (womb). Menstrual blood flows from the uterus through the small opening in the cervix and passes out of the body through the vagina. Most menstrual periods last from 3 to 5 days.
This procedure describes one of the most versatile approaches to the anterior skull base for large tumors of the sinonasal cavity. It may be used with or without a craniofacial resection. The benefits of this approach are: wide access around the tumor; good postoperative cosmesis; & decreased operative & postoperative morbidity. We have used this approach for many bilateral tumors of the nasal & sinus cavities that approach &/or invade the skull base & brain. This video show the resection of a large esthesioneuroblastoma.
Hepatitis and chronic alcohol abuse are frequent causes. Liver damage caused by cirrhosis can't be undone, but further damage can be limited. Initially patients may experience fatigue, weakness, and weight loss. During later stages, patients may develop jaundice (yellowing of the skin), gastrointestinal bleeding, abdominal swelling, and confusion. Treatments focus on the underlying cause. In advanced cases, a liver transplant may be needed.
A brain (cerebral) aneurysm is a bulging, weak area in the wall of an artery that supplies blood to the brain. In most cases, a brain aneurysm causes no symptoms and goes unnoticed. In rare cases, the brain aneurysm ruptures, releasing blood into the skull and causing a stroke. When a brain aneurysm ruptures, the result is called a subarachnoid hemorrhage. Depending on the severity of the hemorrhage, brain damage or death may result. The most common location for brain aneurysms is in the network of blood vessels at the base of the brain called the circle of Willis. What causes a brain aneurysm? A person may inherit the tendency to form aneurysms, or aneurysms may develop because of hardening of the arteries (atherosclerosis) and aging. Some risk factors that can lead to brain aneurysms can be controlled, and others can't. The following risk factors may increase your risk for an aneurysm or, if you already have an aneurysm, may increase your risk of it rupturing: Family history. People who have a family history of brain aneurysms are more likely to have an aneurysm than those who don't. Previous aneurysm. People who have had a brain aneurysm are more likely to have another. Gender. Women are more likely to develop a brain aneurysm or to suffer a subarachnoid hemorrhage. Race. African Americans are more likely than whites to have a subarachnoid hemorrhage. High blood pressure. The risk of subarachnoid hemorrhage is greater in people who have a history of high blood pressure. Smoking. In addition to being a cause of high blood pressure, the use of cigarettes may greatly increase the chances of a brain aneurysm rupturing.
Open heart (coronary artery bypass, or CABG) surgery is performed in order to reroute, or "bypass," blood around blocked arteries, thereby improving the supply of oxygen-rich blood to the heart. Surgeons usually use an artery from the chest wall to construct the "detour" around the blocked part of the artery. Veins from the legs are also used.