Search results
Results From The WOW.Com Content Network
Not all select agents require BSL-4 handling, namely select bacteria and toxins, but most select agent viruses do (with the notable exception of SARS-CoV-1 which can be handled in BSL3). Many non-select agent viruses are often handled in BSL-4 according to facility SOPs or when dealing with new viruses closely related to viruses that require BSL-4.
The effect of the developmental toxicants depends on the type of substance, dose, duration, and time of the exposure. The first few weeks of embryogenesis in humans is more susceptible to these agents. The embryogenesis is the most crucial time for the action of any teratogenic substances to result in birth defects.
While this is still part of the teratological evaluation procedures today, the field of Teratology is moving to a more molecular level, seeking the mechanism(s) of action by which these agents act. One example of this is the use of mammalian animal models to evaluate the molecular role of teratogens in the development of embryonic populations ...
Teratogens are substances that may cause birth defects via a toxic effect on an embryo or foetus. Wikimedia Commons has media related to Teratogens . See also the categories Carcinogens and Mutagens
Teratogens are classified in four main categories: Drugs in pregnancy – in addition to environmental chemicals, includes recreational drug use and pharmaceutical drugs. Vertically transmitted infections; Radiation, such as X-rays; Mechanical forces, such as oligohydramnios; Teratogens affect the fetus by various mechanism including:
Several inhalational anesthetic agents are used in dentistry, e.g., isoflurane, sevoflurane, desflurane, and halothane. [11] The most concerning from the point of view of its health impact, however, is nitrous oxide, an inhalation sedative commonly used in dentistry, particularly for children.
Susceptibility to teratogenesis varies with the developmental stage at the time of exposure to an adverse influence. There are critical periods of susceptibility to agents and organ systems affected by these agents. Teratogenic agents act in specific ways on developing cells and tissues to initiate sequences of abnormal developmental events.
These agents typically include electrophilic groups that react readily with the net negative charge of DNA molecules. [20] Examples of activation-independent carcinogens include ultraviolet light, ionizing radiation and alkylating agents. [21] The time from exposure to a carcinogen to the development of cancer is known as the latency period.