Reverse transcription is necessary for production of HIVs double-stranded DNA, which would be subsequently integrated into the genetic material of the infected cell (where it is called a provirus).Cellular enzymes convert AZT into the effective 5-triphosphate form. Studies have shown that the termination of HIVs forming DNA chains is the specific factor in the inhibitory effect.At very high doses, AZTs triphosphate form may also inhibit DNA polymerase used by human cells to undergo cell division, but regardless of dosage AZT has an approximately 100-fold greater affinity for HIVs reverse transcriptase. The selectivity has been suggested to be due to the cells ability to quickly repair its own DNA chain if it is disrupted by AZT during its formation, whereas the HIV virus lacks that ability. Thus AZT inhibits HIV replication without affecting the function of uninfected cells. At sufficiently high dosages, AZT begins to inhibit the cellular DNA polymerase used by mitochondria to replicate, accounting for its potentially toxic but reversible effects on cardiac and skeletal muscles, causing myositis. Chemistry
Enantiopure AZT crystallizes in the monoclinic space group P21. The primary intermolecular bonding motif is a hydrogen bonded dimeric ring formed from two N-H...O interactions. History
Initial cancer research
In the 1960s, the theory that most cancers were caused by environmental retroviruses gained clinical support and funding. It had recently become known, due to the work of Nobel laureates Howard Temin and David Baltimore, that nearly all avian cancers were caused by bird retroviruses, but corresponding human retroviruses had not yet been found.
If there are attacks more than approximately 3 times per year or severe attacks, surgical excision of the affected gland should be considered. Epidemiology
Sialadenitis of the parotid gland accounts for a much larger percentage of hospital admissions than sialadenitis of the submandibular gland. Submandibular sialadenitis has been said to only account for 10% of all cases diagnosed as sialadenitis. Chronic sialadenitis has been classified as a relatively common presentation, whereas bacterial sialadenitis and sclerosing polycystic sialadenitis are defined as rare. Chronic sclerosing sialadenitis has been shown to affect predominantly males who are over the age of 50, with 40% of cases having an allergic disease, such as chronic sinusitis or bronchial asthma.One study found that 112 patients from England and Wales ranging from 12 to 81 years of age complained of symptoms from their diagnosed sialadenitis, with the group having a mean age of 39 and a standard deviation of 16 years. The study also found that more patients underwent surgery to treat their sialadenitis between the ages of 20 and 69 years but that there were many more patients who complained of symptoms between the ages of 20 and 49, and then went on to be diagnosed with sialadenitis. In each group studied, most patients suffered from sialadenitis in their twenties but there was also found to be a significant number of females whose symptoms started in their thirties and forties.