Unlikely: No evidence of CNS damage. Structural
Structural abnormalities of the brain are observable, physical damage to the brain or brain structures caused by prenatal alcohol exposure. Structural impairments may include microcephaly (small head size) of two or more standard deviations below the average, or other abnormalities in brain structure (e.g., agenesis of the corpus callosum, cerebellar hypoplasia).Microcephaly is determined by comparing head circumference (often called occipitofrontal circumference, or OFC) to appropriate OFC growth charts. Other structural impairments must be observed through medical imaging techniques by a trained physician. Because imaging procedures are expensive and relatively inaccessible to most people, diagnosis of FAS is not frequently made via structural impairments, except for microcephaly.Evidence of a CNS structural impairment due to prenatal alcohol exposure will result in a diagnosis of FAS, and neurological and functional impairments are highly likely.During the first trimester of pregnancy, alcohol interferes with the migration and organization of brain cells, which can create structural deformities or deficits within the brain. During the third trimester, damage can be caused to the hippocampus, which plays a role in memory, learning, emotion, and encoding visual and auditory information, all of which can create neurological and functional CNS impairments as well.As of 2002, there were 25 reports of autopsies on infants known to have FAS. The first was in 1973, on an infant who died shortly after birth.
Mechanism of action
For its use in cancer, its mechanism of action is unknown, but on a cellular level, laboratory tests show that tretinoin forces APL cells to differentiate and stops them from proliferating; in people there is evidence that it forces the primary cancerous promyelocytes to differentiate into their final form, allowing normal cells to take over the bone marrow. Recent study shows that ATRA inhibits and degrades active PIN1.For its use in acne, tretinoin (along with other retinoids) are vitamin A derivatives that act by binding to two nuclear receptor families within keratinocytes: the retinoic acid receptors (RAR) and the retinoid X receptors (RXR). These events contribute to the normalization of follicular keratinization and decreased cohesiveness of keratinocytes, resulting in reduced follicular occlusion and microcomedone formation. The retinoid-receptor complex competes for coactivator proteins of AP-1, a key transcription factor involved in inflammation. Retinoids also down-regulate expression of toll-like receptor (TLR)-2, which has been implicated in the inflammatory response in acne. Moreover, tretinoin and retinoids may enhance the penetration of other topical acne medications.The combination of the 10% benzoyl peroxide and light results in more than 50% degradation of tretinoin in about 2 hours and 95% in 24 hours. This lack of stability in the presence of light and oxidizing agents has led to the development of novel formulations of the drug. When microencapsulated tretinoin is exposed to benzoyl peroxide and light only 1% degradation takes place in about 4 hours and only 13% after 24 hours. Biosynthesis
Tretinoin is synthesized from beta-carotene.