Studies have shown that television competes with other sources of human interaction—such as family, friends, church, and school—in helping young people develop values and form ideas about the world around them. Between the s and s, commercial television had a profound and wide-ranging impact on American society and culture. It influenced the way that people think about such important social issues as race, gender, and class.
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National Academy of Sciences, ' These authors have also presented unpublished information from eleven Adverse Drug Reaction Reports associated with the use of vitamin A during pregnancy that were filed with the FDA. The biases that contributed to the decision to report or publish these cases of malformed vitamin A-exposed infants are unknown but are probably substantial.
Some of these infants have malformations similar to those found among isotretinoin-exposed infants; the malformations of the others were quite different. At best, it can be said that the malformations of some of the vitamin A-exposed infants fit the pattern of malformation seen among infants exposed to isotretinoin.
There are no epidemiologic studies that provide the data necessary to quantitate the risk for major malformation following daily fetal exposure to supplements of any dose of vitamin A. After the initial report of three malformed infants Roche Laboratories '83epidemiologic evidence began to accumulate that isotretinoin is a human teratogen Rosa, ' The malformations involved craniofacial, central nervous system, cardiac, and thymic structures.
Isotretinoin-exposed infants were 26 times more likely to have brain, cardiac, or ear malformations than unexposed infants.
The brain malformations included hydrocephalus several typesmicrocephaly, cerebellar micro- and macrodysgenesis, and other abnormalities which can be via neuronal migrational defects. Cardiac malformations included aorticopulmonary septation abnormalities or conotruncal developmental defects Lammer and Opitz, ' Most of the mothers of affected infants took daily doses of isotretinoin at levels of 0.
Can we extrapolate from the known teratogenic daily dose of isotretinoin to an equivalent intake of vitamin A? Probably not at this time. We know that the malformations in laboratory animals and humans after isotretinoin treatment are strikingly similar.
Yet the pharmacologic differences between vitamin A and isotretinoin make it difficult to estimate the amount of each compound to which an embryo is exposed when comparable amounts have been taken orally.
For example, the relative teratogenic concentrations for various retinoids could be determined by using whole postimplatation rodent embryo cultures; however, there are no widely accepted procedures to extrapolate these data to the pregnant human.
Finally, in a single case, regardless of vitamin A intake, one cannot impute the cause of birth defects to vitamin A based upon present knowledge. It is essential to evaluate these concerns in a systematic manner Shepard '73 '86; Wilson '77; Brent '78, '86a, '86b; Stein et al.
Do human clinical studies or epidemiological studies consistently support the concept that high doses of vitamin A may be teratogenic and produce a recognizable group of malformations?
No human epidemiologic studies are available. Although not conclusive, the case reports suggest that high doses of vitamin A may be teratogenic, since some of the infants had malformations that fit the recognizable pattern that occurred following human exposure to isotretinoin. Do secular trends of high-dose vitamin A exposure and the birth prevalence of malformations correlate?
There is sufficient information concerning trends in exposures to high-dose vitamin A and concerning knowledge of defects that may be induced by use of vitamin A. Does vitamin A induce malformations in experimental animals following exposures to doses that are pharmacologically comparable to the maternal use 25, IU or more of one or several unit doses per day of the vitamin A products that are available to the public?
Is the frequency of malformations dose related and in the pharmacologic range of human toxic exposures? Data are not available for the human. Is it biologically plausible that high doses of vitamin A may cause birth defects in the human? Yes, isotretinoin is a known human teratogen. Since isotretinoin and vitamin A retinol and retinyl esters induce similar patterns of malformations in animals, it is probable that similar pathogenetic mechanisms are involved in inducing the malformations.
Currently there is no evidence to suggest that vitamin A should act differently than isotretinoin in the human conceptus. Beta-carotene, a provitamin A, does not produce vitamin A toxicity nor does it produce teratogenicity in animals. All of these data are consistent with a specific vitamin A-related teratogenic response.
Editorial Vitamin A and teratogenesis Lancet, I: Definition of a teratogen and the relationship to carcinogenicity. In Clinics in Perinatology, R. From nutrition to pharmacology in dermatology and oncology. Matter From vitamin A to retinoids in experimental and clinical oncology: Achievements, failures and outlook.Get the latest news and analysis in the stock market today, including national and world stock market news, business news, financial news and more.
🔥Citing and more! Add citations directly into your paper, Check for unintentional plagiarism and check for writing mistakes. 1 Retinol or retinyl esters 2 See Food and Nutrition Board: National Academy of Sciences, ' 3 Kamm, '82; Kamm et al, ' 4 Rosa et al., ' At least seven case reports of adverse pregnancy outcome associated with a daily intake of vitamin A of 25, IU or more have been published (Rosa et al., '86).
Research on exposure to television and movie violence suggests that playing violent video games will increase aggressive behavior. A meta-analytic review of the video-game research literature reveals that violent video games increase aggressive behavior in children and young adults.
Textual Analysis of Writing Guides - Let me introduce you to the main characters in the story of composition. Our hero—the protagonist—is known as “the writer,” who is supported by both the writing instructor—our hero’s mentor traditionally—and the reference guide.
Literature is a collected body of written works that includes not only religious texts and bulky novels, but also plays, poetry and short stories, all of which reflect the authors perceptions of society and the human condition at the period in history when the works were written.