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(cryptorchidism) is a testicle that hasn't moved into its proper position in the bag of skin hanging below the penis (scrotum) before birth. Usually just one testicle is affected, but about 10 percent of the time both testicles are undescended. An undescended testicle is uncommon in general, but common among baby boys born prematurely. The vast majority of the time, the undescended testicle moves into the proper position on its own, within the first few months of life. If your son has an undescended testicle that doesn't correct itself, surgery can relocate the testicle into the scrotum.
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.
arteriovenous hemodialysis access has been the "gold standard" for patients needing hemodialysis for the past 30 years. Despite the reported advantages of autologous access, the availability of prosthetic graft material, coupled with the challenging dialysis candidate, has led to a trend of primary prosthetic graft dialysis access in the 1980s and 1990s. In recognition of this unfortunate trend, the National Kidney Foundation Dialysis Outcomes Quality Initiative (DOQI) used evidence from published studies and summary articles to generate clinical practice guidelines, emphasizing a shift back to autologous arteriovenous fistula (AVF) as the key to long-term successful hemodialysis.[1,2] These initial guidelines proposed a goal of 50% autologous AVF as the initial access, with a 40% prevalence of autologous access for a given practice or unit.
These are a few common types of benign bone tumors: Osteochondroma is the most common benign bone tumor. ... Giant cell tumor is a benign tumor, typically affecting the leg (malignant types of this tumor are uncommon). Osteoid osteoma is a bone tumor, often occurring in long bones, that occurs commonly in the early 20s.
Testicular torsion occurs when a testicle rotates, twisting the spermatic cord that brings blood to the scrotum. The reduced blood flow causes sudden and often severe pain and swelling. Testicular torsion is most common between ages 12 and 16, but it can occur at any age, even before birth. Testicular torsion usually requires emergency surgery. If treated quickly, the testicle can usually be saved. But when blood flow has been cut off for too long, a testicle might become so badly damaged that it has to be removed.
Definition. The principal signs of cerebellar dysfunction are the following: Ataxia: unsteadiness or incoordination of limbs, posture, and gait. A disorder of the control of force and timing of movements leading to abnormalities of speed, range, rhythm, starting, and stopping.
Phlebitis may occur with or without a blood clot. It can affect surface or deep veins. When caused by a blood clot, it's called thrombophlebitis. Trauma to the vein, for instance from an IV catheter, is a possible cause. Symptoms include redness, warmth, and pain in the affected area. Treatments may include a warm compress, anti-inflammatory medication, compression stockings, and blood thinners.
Several options are available to remove spider veins — thin red lines or weblike networks of blood vessels that appear on your legs and feet. Spider veins are usually harmless, though they can sometimes cause aching, burning or pain, especially when you've been standing for long periods. If you have symptoms or are concerned about the appearance of spider veins, treatment options include: Sclerotherapy. In this procedure, your doctor injects the veins with a solution that scars and closes those veins, causing the blood to reroute through healthier veins. In a few weeks, treated spider veins fade. Although the same vein may need to be injected more than once, sclerotherapy is usually effective if done correctly. Sclerotherapy doesn't require anesthesia and can be done in your doctor's office. Side effects include swelling, itching and skin color changes in the treated area. Laser surgery. Laser surgery works by sending strong bursts of light into the vein that make the vein slowly fade and disappear. No incisions or needles are used. The treatment is often less effective than sclerotherapy, particularly for larger veins. Side effects may include redness, bruising, itching, swelling and permanent skin tone changes. After treatment, blood vessels fade over several months, but they may not disappear completely. Also, new spider veins can develop in the same area.
An AV fistula is a connection, made by a vascular surgeon, of an artery to a vein.Vascular surgeons specialize in blood vessel surgery. The surgeon usually places an AV fistula in the forearm or upper arm. An AV fistula causes extra pressure and extra blood to flow into the vein, making it grow large and strong.
Gastroesophageal reflux disease (GERD) is a chronic digestive disease. GERD occurs when stomach acid or, occasionally, stomach content, flows back into your food pipe (esophagus). The backwash (reflux) irritates the lining of your esophagus and causes GERD. Both acid reflux and heartburn are common digestive conditions that many people experience from time to time. When these signs and symptoms occur at least twice each week or interfere with your daily life, or when your doctor can see damage to your esophagus, you may be diagnosed with GERD. Most people can manage the discomfort of GERD with lifestyle changes and over-the-counter medications. But some people with GERD may need stronger medications, or even surgery, to reduce symptoms.
An unnamed Russian scientist has introduced the concept of a device that attaches to the wall of the artery. It would first stop blood flow to the area to prevent breakaway plaque. A drill would then scrape the plaque from the artery wall. The procedure of treating plaque buildup could include bypass surgery, stent replacement and balloon angioplasty. Since the plaques are of different types and locations in the body, the inventor proposed using different types of cutting mills.
Pulmonary embolism symptoms can vary greatly, depending on how much of your lung is involved, the size of the clots, and whether you have underlying lung or heart disease. Common signs and symptoms include: Shortness of breath. This symptom typically appears suddenly and always gets worse with exertion. Chest pain. You may feel like you're having a heart attack. The pain may become worse when you breathe deeply (pleurisy), cough, eat, bend or stoop. The pain will get worse with exertion but won't go away when you rest. Cough. The cough may produce bloody or blood-streaked sputum. Other signs and symptoms that can occur with pulmonary embolism include: Leg pain or swelling, or both, usually in the calf Clammy or discolored skin (cyanosis) Fever Excessive sweating Rapid or irregular heartbeat Lightheadedness or dizziness
Hirschsprung's (HIRSH-sproongz) disease is a condition that affects the large intestine (colon) and causes problems with passing stool. The condition is present at birth (congenital) as a result of missing nerve cells in the muscles of the baby's colon. A newborn who has Hirschsprung's disease usually can't have a bowel movement in the days after birth. In mild cases, the condition might not be detected until later in childhood. Uncommonly, Hirschsprung's disease is first diagnosed in adults.