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Archive for the ‘Pathology’ Category

Free Medical Books & Study Guides – Scribd

Posted by medliorator on April 17, 2009

Scribd is a place where you publish, discover and discuss original writings and documents.  Medical students may find some tasty tidbits in this vast archive.

For example,

USMLE – BRS Pathology – Flash Cards

screenhunter_03-apr-11-1941

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Video Review of Pathology – DoctorsTube

Posted by medliorator on April 6, 2009

DoctorsTube – A large database of pathological states accompanied by video selections.

This collection is an excellent review tool for general pathology, and the added video component facilitates long-term retention.

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Keloid Review

Posted by medliorator on February 4, 2009

fibrous growths that uncommonly occur in cases of wound healing. They present predominantly in blacks, and any type of skin piercing can affect those predisposed to the disease.

The first-line therapy is injection of steroids into the keloid, with a 70 percent response rate. Surgical excision alone is not effective, as this option is often followed by a high frequency of recurrence.

When ear piercings lead to keloid formation [Kevin MD]

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Traction Alopecia

Posted by medliorator on September 4, 2008

There are many causes of hair loss including medications, thyroid disease, iron deficiency, even having a baby. Most of these causes result in temporary hair loss — the hair eventually grows back. Some types of hair loss, however, are permanent; this is called scarring or cicatrical alopecia. A common scarring hair loss in women is traction alopecia.

Traction alopecia occurs when hair is pulled too tightly for long periods of time. It occurs often in girls and women who braid their hair, but can also be seen in women who pull their hair back tightly in a pony-tail or a bun. Over months and years the hair loss becomes permanent, and cannot regrow. It can be seen in men, but is more common in women. It can also affect children as well as in adults.

The best treatment is to release the tension on your hair as much as possible as soon as possible. This is often difficult because it requires adopting a different hairstyle

Hair Loss 101: Traction Alopecia [The Derm Blog]

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New Alzheimer’s Drug Targets Tau Tangles

Posted by medliorator on July 30, 2008

methylthioninium chloride, is the first treatment specifically designed to target the Tau tangles.

Other treatments for Alzheimer’s tend to focus on combating a waste protein in the brain, beta-amyloid, which is known to form hard plaques. The latest work suggests targeting Tau may produce better results.

Trials of the drug, known as Rember, in 321 patients showed an 81% difference in rate of mental decline compared with those not taking the treatment.

Larger trials of the drug are planned to start in 2009, and researchers are also investigating whether the drug has a role in prevention of the disease in the first place.

Alzheimer’s drug ‘halts’ decline [BBC]

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IBS Drug Approved

Posted by medliorator on May 4, 2008

The Food and Drug Administration on Tuesday approved the first U.S. drug to treat irritable bowel syndrome with constipation (IBS-C) in adult women, a medicine marketed by Takeda Pharmaceutical Co and its developer, Sucampo Pharmaceuticals Inc.

The drug, Amitiza, was approved for women over 18 years old, but not for men, because its effectiveness was not conclusively demonstrated, the FDA said in a statement.

The safety and effectiveness of Amitiza was established in two studies involving 1,154 patients diagnosed with IBS-C, the agency said. More than 90 percent of patients in the studies were women.

The drug was found to have some side effects, such as nausea, diarrhea, and abdominal pain, the FDA said.

FDA approves irritable bowel drug [Reuters]

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Basic Pathology Terms

Posted by medliorator on January 6, 2008

Infection: detrimental colonization of a host organism by a foreign species.
the infecting organism seeks to utilize the host’s resources to multiply (usually at the expense of the host). The infecting organism, or pathogen, interferes with the normal functioning of the host and can lead to chronic wounds, gangrene, loss of an infected limb, and even death.The host’s response to infection is inflammation (read below). Colloquially, a pathogen is usually considered a microscopic organism though the definition is broader, including feces, parasites, fungi, viruses, prions, and viroids. A symbiosis between parasite and host, whereby the relationship is beneficial for the former but detrimental to the latter, is characterised as parasitism.

 

The branch of medicine that focuses on infections and pathogens is infectious disease.

 

Inflammation: complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. It is a protective attempt… to remove the injurious stimuli as well as initiate the healing process. Inflammation is not a synonym for infection… infection is caused by an exogenous pathogen, while inflammation is the response of the organism to the pathogen.

 

In the absence of inflammation, wounds and infections would never heal and progressive destruction of the tissue would compromise the survival of the organism. However, inflammation which runs unchecked can also lead to a host of diseases, such as hay fever, atherosclerosis, and rheumatoid arthritis. It is for this reason that inflammation is normally tightly regulated by the body.

 

Inflammation can be classified as either acute or chronic.

 

Necrosis: accidental death of cells and living tissue. Necrosis is less orderly than apoptosis, which is part of programmed cell death. In contrast to apoptosis, cleanup of cell debris by phagocytes of the immune system is generally more difficult, as the disorderly death generally does not send cell signals which tell nearby phagocytes to engulf the dying cell. This lack of signalling makes it harder for the immune system to locate and recycle dead cells which have died through necrosis than if the cell had undergone apoptosis.

 

The release of intracellular content after cellular membrane damage is the cause of inflammation in necrosis. There are many causes of necrosis including prolonged exposure to injury, infection, cancer, infarction, poisons, and inflammation. Severe damage to one essential system in the cell leads to secondary damage to other systems, a so-called “cascade of effects”. Necrosis can arise from lack of proper care to a wound site.

 

Necrosis is accompanied by the release of special enzymes, that are stored by lysosomes, which are capable of digesting cell components or the entire cell itself. The injuries received by the cell may compromise the lysosome membrane, or may initiate an unorganized chain reaction which causes the release in enzymes.

 

Unlike apoptosis, cells that die by necrosis may release harmful chemicals that damage other cells. In biopsy, necrosis is halted by fixation or freezing.

 

Atrophy: partial or complete wasting away of a part of the body. Causes… include poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself. Hormonal and nerve inputs that maintain an organ or body part are referred to as trophic.

 

Atrophy is a general physiological process of reabsorption and breakdown of tissues, involving apoptosis on a cellular level. When it occurs as a result of disease or loss of trophic support due to other disease, it is termed pathological atrophy, although it can be a part of normal body development and homeostasis as well.

 

Hypertrophy: increase of the size of an organ or in a select area of the tissue. It should be distinguished from hyperplasia which occurs due to cell division increasing the number of cells while their size stays the same; hypertrophy occurs due to an increase in the size of cells, while the number stays the same.

 

Fibrosis: formation or development of excess fibrous connective tissue in an organ or tissue as a reparative or reactive process, as opposed to a formation of fibrous tissue as a normal constituent of an organ or tissue.

 

Tuberculosis: a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. Tuberculosis most commonly attacks the lungs (as pulmonary TB) but can also affect the central nervous system, the lymphatic system, the circulatory system, the genitourinary system, bones, joints and even the skin.

 

Other mycobacteria such as Mycobacterium bovis, Mycobacterium africanum, Mycobacterium canetti, and Mycobacterium microti can also cause tuberculosis, but these species do not usually infect healthy adults.

 

Over one-third of the world’s population has been exposed to the TB bacterium, and new infections occur at a rate of one per second. Not everyone infected develops the full-blown disease; asymptomatic, latent TB infection is most common. However, one in ten latent infections will progress to active TB disease, which, if left untreated, kills more than half of its victims.

 

In 2004, mortality and morbidity statistics included 14.6 million chronic active TB cases, 8.9 million new cases, and 1.6 million deaths, mostly in developing countries. In addition, a rising number of people in the developed world are contracting tuberculosis because their immune systems are compromised by immunosuppressive drugs, substance abuse, or HIV/AIDS. The rise in HIV infections and the neglect of TB control programs have enabled a resurgence of tuberculosis.

 

Sarcoidosis: an immune system disorder characterised by non-caseating granulomas (small inflammatory nodules) that most commonly arises in young adults. The cause of the disease is still unknown. Virtually any organ can be affected; however, granulomas most often appear in the lungs or the lymph nodes.

 

Symptoms can occasionally appear suddenly but usually appear gradually. The clinical course varies and ranges from asymptomatic disease that resolves spontaneously to a debilitating chronic condition that may lead to death.

 

Granuloma: a group of epithelioid macrophages surrounded by a lymphocyte cuff. Granulomas are small nodules… seen in a variety of diseases such as Crohn’s disease, tuberculosis, Leprosy, sarcoidosis, berylliosis and syphilis. It is also a feature of Wegener’s granulomatosis and Churg-Strauss syndrome, two related autoimmune disorders.

 

An important aspect of granulomas is whether they are caseating or not. Caseation (literally: turning to cheese) is a form of necrosis at the centre of a granuloma and is a feature of the granulomas of tuberculosis.

Pathology Terms (part1) [My MD Journey]

Posted in Pathology | 2 Comments »

MRSA: What Med Students Should Know

Posted by medliorator on December 5, 2007

by Alison Hayward, M.D.
SDN Staff Writer

MRSA rose to prominence last month when a CDC report published in JAMA estimated that nearly 19,000 people had died of MRSA infections in 2005. Compare that with AIDS, which killed about 17,000 in the same year,

 

Staphylococcus aureus is a bacterium that was discovered in 1880 in surgical abscesses. Staph has a talent for antibiotic resistance, and it became resistant to penicillin nearly immediately after penicillin was introduced in the 1940s. Methicillin is an antibiotic that was used to treat this penicillin-resistant staph, but as the bug continued to collect resistances, MRSA was born.

 

MRSA is a strain of staph that was identified in 1961. MRSA is by no means a new bacteria, it is only new to the public consciousness. Due to the mathematics of infectious disease, MRSA has exploded along an exponential curve and now represents the majority of all staph infections seen in ICUs and in the ED.

 

MRSA is potentially lethal, as is its parent, the pan-sensitive Staph aureus, often via bloodstream infections or bacteremia that leads to sepsis and ultimately to septic shock. However, MRSA is not deemed a superbug simply due to its resistance. It also has increased morbidity due to the accumulation of toxin genes via bacteriophages, such as Panton-Valentine leukocidin (PVL). A bacteriophage is basically a virus containing a snippet of DNA that can spread through a population of bacteria, similarly to the way a bacterial infection spreads through a human population. PVL is called a ‘leukocidin’ because it has the ability to burst white blood cells (leukocytes).

 

MRSA can be treated empirically with vancomycin, a “big gun” antibiotic. However, many may not be aware that MRSA is also often susceptible to such “small guns” as doxycycline or trimethoprim/sulfamethoxazole. As with any infectious disease, the best strategy is to start broad coverage antibiotics immediately with any suspicion of MRSA infection, and then to narrow coverage based on culture and sensitivity results. A CA-MRSA abscess, the most common manifestation that a normal, immunocompetent member of the community might face, can still be treated with a simple incision and drainage (I&D) of the wound. CDC recommendations suggest not adding antibiotic coverage unless the patient is immunocompromised, has severe local symptoms or signs of systemic infection, or does not respond to I&D. Antibiotic choices for outpatient treatment of MRSA skin infection include clindamycin and doxycycline.

  • Colonization with MRSA does not equal infection. Many people (an estimated 2 million in the U.S.) carry MRSA with no symptoms at all.
  • MRSA infection is treatable with proper antibiotics, and does not always require antibiotics.
  • Simple prevention strategies can greatly reduce the likelihood of a MRSA infection, particularly a severe one.

Community Acquired (CA)-MRSA and Hospital Acquired (HA)-MRSA have historically been significantly different bacteria. HA-MRSA strains tend to have accumulated resistance to more antibiotics, but CA-MRSA is actually more toxic. CA-MRSA can replicate more rapidly and is more often associated with PVL toxin, presumed to be a key factor in how CA-MRSA infections notoriously produce necrotic lesions such as abscesses or hemorrhagic pneumonia. New studies have shown that CA-MRSA can basically pulverize white cells, with or without PVL toxin, and that makes CA-MRSA hard for our bodies to defend against despite the fact that it is not resistant to as many antibiotics as its hospital-acquired cousin. There are several of these highly virulent strains of CA-MRSA that are now wreaking havoc in the community, the most famous of which is the USA300 strain.

MRSA: What Health Care Providers Should Know [Student Doctor Network]

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10 Basic Medical Definitions

Posted by medliorator on November 18, 2007

These words are worth sorting out. A mix up can compromise your chart/testimony.

1. Abrasion = A superficial injury to the skin or other body tissue caused by rubbing or scraping resulting in an area of body surface denuded of skin or mucous membrane.

2. Incision = A cut or wound made by a sharp instrument or object.

3. Laceration = A wound produced by the tearing of body tissue often from blunt impact that is distinguished from a cut or incision.

4. Avulsion = The tearing away of a structure or part often seen as a partial avulsion.

5. Patterned Injury = An injury resembling the object or mechanism that caused the injury.

6. Pattern of Injury = Injuries in various stages of healing, including old and new scars, contusions, and wounds.

7. Contusion = A Bruise. An injury of tissue without breakage of skin. Blood accumulates in the surrounding tissue producing pain, swelling, tenderness, and discoloration.

8. Hemorrhage = The escape of blood from the vessels, bleeding.

9. Petechia = A pinpoint, nonraised, perfectly round, purplish red spot caused by intradermal or submucous haemorrhage.

10. Ecchymosis = A small haemorrhagic spot, larger than a petechia, in the skin or mucous membrane forming a nonelevated, rounded or irregular, blue or purplish patch.

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