Archive for March 27th, 2009

HIV TREATMENT: USING DIFFERENT MEDICATION

Friday, March 27th, 2009

When to start the medications is also a topic of much discussion and controversy. Before the development of protease inhibitors, initiation of antiretroviral medications was considered when the T-helper-cell count fell below 500. Use of medications was not recommended earlier in the course of the infection for fear that once they were necessary (when the T-helper-cell count began to fall and the consequent risk of opportunistic infections began to rise), they might no longer be effective. AZT, ddl, and ddC, when used as monotherapy, often become ineffective after six to twelve months because of the development of resistance. Combination therapy offers longer suppression of the virus and can decrease the likelihood that resistance will develop. Combining 3TC with AZT will prevent resistance to the AZT from developing, so that combination is now preferred over the use of either drug alone. The protease inhibitors are even more effective in combination with the anti-retrovirals in maintaining T-cell count and decreasing viral load. The use of two antiretrovirals with a protease inhibitor (a strategy called triple therapy) has also been tried, and it is now the preferred regimen for many patients because of its increased effectiveness.

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BARRIERS FOR PREVENTION THE TRANSMISSION OF HEPATITIS B

Friday, March 27th, 2009

For a child born to a mother who is infected with hepatitis B, the same combination of vaccine series and immune globulin is given, usually within twelve hours of birth. This treatment has a high rate of success in preventing the child from becoming infected with hepatitis B, decreasing the likelihood of infection from 80 percent to 5-15 percent. All pregnant women should be tested to determine their hepatitis B status, so that their newborns can be tested and treated if they have been exposed.

Besides vaccination, the other method to help prevent the transmission of hepatitis B through sexual contacts is to use condoms or other barriers for oral, anal, and genital intercourse if a partner’s status for hepatitis B (and other STDs) is not known. However, since condoms can break or may be used improperly, they should not be relied on as the sole means of preventing infection. Women who have sex with other women can transmit the virus through oral sex and exchange of vaginal secretions. Dental dams or plastic wrap may decrease the risk of infection in such cases.

All partners of these found to be infected with hepatitis B should be immunized.

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STD CHLAMIDIA INFECTION: HOW COMMON IS IT?

Friday, March 27th, 2009

Chlamydia is the most common bacterial sexually transmitted disease in the industrialized world. Estimates are that between four and six million people are infected each year with chlamydia in the United States, but this may be an underestimate. Many people are symptom free and are never diagnosed or reported. Studies have shown that between 3 and 5 percent of men and women in general medical clinics and about 15-20 percent of men and women attending STD clinics are infected. Studies of symptom-free people in various areas of the country have found that between 5 and 50 percent of those tested are infected with chlamydia. About half of those infected are teenagers, and about one-third are between twenty and twenty-four years old.

Even though chlamydia is a common infection of adolescents and young adults in the United States, any sexually active person can become infected. Younger women are more likely to become infected with chlamydia if exposed because the anatomy of the cervix makes them vulnerable.

Because many people have chlamydia without experiencing any symptoms, it is an infection that is frequently passed between sexual partners unknowingly. People of any sexual orientation can become infected with chlamydia, although it appears to be more common among those who have opposite-sex partners. Women who have sex with other women may be the least likely to become infected, although there is a small possibility of infection if they share sex toys. Routinely screening those at high risk for chlamydia is the only way to halt the spread of this epidemic.

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STAGING PROSTATE CANCER: MORE ON TRANSRECTAL ULTRASOUND AND STAGING

Friday, March 27th, 2009

Most studies have found transrectal ultrasound to be a rather mediocre predictor of the presence of cancer that has penetrated the prostate wall, and to be downright poor in finding cancer that has reached the seminal vesicles. In two studies, only 30 percent of tumors that had spread to the seminal vesicles could be found by ultrasound. One investigation, of thirty men undergoing radical prostatectomy, found ultrasound’s sensitivity in spotting cancer that had worked its way beyond the prostate wall was a measly 5 percent. Another study, comparing ultrasound and pathological staging in 121 men, found ultrasound’s overall accuracy in staging was only 66 percent—better, but still not reliable enough. And a multicenter study of 230 men found that ultrasound correctly staged 66 percent of locally advanced cancer and only 46 percent of the cancers confined to the prostate.

Ultrasound’s main difficulty is its inability to “see” microscopic cancer spread. So, to sum up: No definitive decision about a man’s course of treatment should be made on the basis of ultrasound alone, and ultrasound readings shouldn’t be the cause of a man’s exclusion from surgery that could potentially cure his disease.

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THE QUICK GUIDE TO THE REPRODUCTIVE SYSTEM

Friday, March 27th, 2009

Now, let’s take a quick look at the reproductive system:

Sperm and testosterone, the male hormone, are made in the testicles. Testosterone is the substance that makes the prostate grow at puberty; it also stimulates the prostate to manufacture its secretions. Sperm travel from the testicles to the twisting, winding epididymis, a convoluted “greenhouse” where they mature.

The epididymis connects to the vas deferens, a hard, muscular cord that winds all the way from the scrotum into the body and down to the back of the prostate. At this point, the seminal vesicles, which produce 70 percent of the fluid for semen, connect to the vas deferens to form the ejaculatory ducts, which run into the center of the prostate. When a man ejaculates, sperm rocket from the epididymis through the vas deferens and out of the ejaculatory duct, where they’re mixed with the fluids from the prostate and seminal vesicles.

To make sure that the semen doesn’t “back up” into the bladder, a muscular valve slams shut in the bladder neck, forcing the semen out the urethra in the penis. Soon after ejaculation, the semen coagulates. A substance called prostate-specific antigen (PSA), which is made by the prostate, then acts on the semen, causing it to become liquid again.

To understand what can go wrong with the prostate, it will probably help to study the illustrations in this chapter and the rest of the book (the illustration in the Glossary shows the male urinary and reproductive systems together). The prostate encircles the urethra like a fist holding a straw—therefore, when its transition zone enlarges, in benign prostatic hyperplasia (BPH), this compresses the urethra and causes urinary problems. Finally, by understanding how PSA is secreted from ducts in the prostate, you’ll be able to see why PSA levels increase when these ducts become obstructed, as they do in prostate cancer.

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