Saturday, December 25, 2010

lymphoid organs (Organs of the Immune System)

The organs of the immune system are positioned throughout the body. They are called lymphoid organs because they are home to lymphocytes, small white blood cells that are the key players in the immune system.

Bone marrow, the soft tissue in the hollow center of bones, is the ultimate source of all blood cells, including ......................


Classification of inflammatory arthritis

Inflammatory arthritis is generally classified into seropositive and seronegative groups. These are based on the presence of rheumatoid factor, an immunoglobulin which reacts with gamma globulin, in the blood of the majority of patients with seropositive disease and in a small minority of patients with seronegative disease. The prototype seropositive form of arthritis is rheumatoid arthritis. Other members include the group of conditions labelled collagen vascular diseases, such as systemic lupus erythematosus, scleroderma, vasculitis, Sjogren’s syndrome. Only rheumatoid arthritis will be considered in this paper.

Among the seronegative inflammatory joint diseases is a group labelled spondyloarthritis. This condition is characterized by inflammatory disease of the joints of the back, both the sacroiliac joints and the apophyseal joints of the spine. Members of this group include ankylosing spondylitis, psoriatic arthritis, reactive arthritis, and arthritis of inflammatory bowel disease. While the prototype for this group is ankylosing spondylitis, psoriatic arthritis will also be discussed.

In addition to the presence of rheumatoid factor, there are extra-articular features which distinguish the seropositive from the seronegative forms of inflammatory arthritis.

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A case of Inflammatory Arthritis

A 34 year old male has a long history of several subacute attacks of self-limited inflammatory arthritis. Crystals have been retrieved from a joint aspirate. Radiography of his knee is likely to demonstrate:

subperiosteal thickening
b) marginal articular erosions
c) central articular erosions
d) chondrocalcinosis
e) subchondral bony sclerosis

The correct answer is D

Chondrocalcinosis is simply the term for the finding of radio-opaque crystals in hyaline or fibrocartilage. These salts may consist of calcium pyrophosphate dihydrate, dicalcium phosphate dihydrate or hydroxyapatite. Crystals may also be deposited in bursae, capsules, ligaments and tendons.
Chondrocalcinosis may accompany a variety of diseases, but is not a disease entity merely a physical sign thereof. Used properly, the term pseudogout refers to the clinical syndrome of one or more acute or subacute attacks of self-limited inflammatory arthritis caused by crystal-induced synovitis, proven by recovery of the crystals from a joint aspirate. Most people with chondrocalcinosis never have a single acute episode of pseudogout.

CPPD crystal deposition disease is the general term that encompasses chondrocalcinosis, pseudogout, a distinctive arthropathy and a host of variations. During acute attacks (pseudogout) of crystal-induced synovitis, the usual radiological findings are soft-tissue oedema and joint effusion. Chondrocalcinosis may or may not be present. The cartilage and articular bone are often normal. The chronic arthropathy is more distinctive. It is most frequent in the patellofemoral, radiocarpal metacarpophalangeal and elbow joints.

Although the findings superficially resemble osteoarthritis, there are several important differences beyond the unique distribution. The arthropathy is characterized by cartilage loss, multiple subchondral cystic rarefactions, structural collapse of the articular surface, and the presence of many small intra-articular fragments, all without much bone sclerosis. In addition to the usual target sites, these changes may be observed in the hips, knees and sacroiliac joints. Chondrocalcinosis, which does not have to accompany the arthropathy, is seen most commonly in the large joints such as the knee, hip and shoulder as well as the symphysis pubis.

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Katzung & Trevor's Pharmacology Examination and Board Review, 9th Edition

The most trusted and efficient pharmacology review – complete with 1000+ Q&As — and now in full color

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From the authors of Basic and Clinical Pharmacology, the leading pharmacology textbook, here is the newest edition of the best review book available for medical pharmacology course exams and board examinations. This skill-building guide comes with over 1000 review questions and answers –- far more than most other pharmacology reviews –- and a chapter-based approach that facilitates use with course notes or larger texts.

* A new full-color presentation

* Organized to reflect course syllabi, focusing on the clinical use and pharmacology of drug categories, rather than individual drugs

* Two complete practice exams

* A valuable appendix of test-taking strategies

* Chapters that include valuable learning aids such as:

–Short discussion of the major concepts that underlie basic principles or drug groups

–Explanatory figures and tables

–Review questions followed by answers and explanations

–Drug Trees in drug-oriented chapters that visually organize drug groups

–A list of high-yield terms and definitions you need to know

* Skill Keeper questions that prompt you to review previous material to understand links between related topics

* A checklist of tasks you should be able to do, once you have finished the chapter

* Summary Tables that list the important drugs and include key information about their mechanisms of action, effects, clinical uses, pharmacokinetics, drug interactions, and toxicities.

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Testicular microliths in a new born

The above ulltrasound images and Color Doppler image show testicular microliths (left testis) in a new born baby.
Testicular calcifications can occur in any age group; however the occurrence of this condition in a newborn is very rare. The color Doppler study showed normal vascularity in the affected testis.  
Such cases need to be followed up for changes such as germ cell tumor and more benign conditions such as epididymitis, orchitis and varicocele as well as testicular atrophy. Studies show possible link between Testicular microlithiasis in infants and Down's syndrome.

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Normal vs. Cancerous Testicle

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