The cells of the blastocyst inner cell mass only remain pluripotent for a short time. This state of pluripotency and self-renewal can be maintained in embryonic stem (ES) cell culture by adding specific chemicals or growth factors to ensure the cells can continue dividing and later differentiate into different cell types. In some cases, the cells are grown on a feeder layer of differentiated cells, which provides the growth factors and extracellular matrix components necessary for stem cell...

Ethanol, a clear colorless alcohol, has been consumed by humans for millennia, but its effects on the body are far from benign. At lower doses, it induces decreased inhibitions and loquaciousness, leading to its social appeal. However, it can cause severe consequences at higher doses, such as coma and respiratory depression, due to its zero-order elimination kinetics. Chronic ethanol abuse wreaks havoc on multiple organ systems, particularly the CNS and the liver. Abrupt cessation of ethanol...

CNS depressants include drugs from the category of barbiturates and benzodiazepines. They are valuable medications for managing anxiety disorders and insomnia. Barbiturates, once used to induce and maintain sleep, have been replaced mainly by benzodiazepines due to barbiturate's toxicity, tolerance, and overdose risks. They interact with GABAA receptors, leading to sedation at low doses and potentially coma and death at higher doses. Phenobarbital, a long-acting barbiturate, possesses...

Hallucinogens, also known as psychedelic drugs, are a class of substances known for their ability to alter perception, cognition, and emotions. Despite their profound effects on the mind, these drugs are non-addictive, setting them apart from many other abused substances. The mechanism of action of these drugs lies in their impact on the 5-HT2A receptor in the brain. Upon activation, this receptor couples to Gq-type G proteins, triggering a cascade that releases intracellular calcium. This...

The Self-Evaluation Maintenance (SEM) model offers a psychological framework to understand how individuals’ self-esteem is influenced by the achievements of others, particularly those with whom they share close personal bonds. The SEM model operates when personal rather than social identity guides individuals. Central to this model is the notion that individuals have an inherent desire to preserve a favorable self-image, which is continuously shaped by interpersonal comparisons and...

CNS stimulants, such as cocaine, amphetamines, and cannabinoids, have varying structures and mechanisms of action that lead to different therapeutic effects and side effects. Cocaine, with its molecular formula C17H21NO4, is a tropane alkaloid and a tertiary amino compound. It has two chemical forms: the hydrochloride salt and the "freebase." The former is in powder form, while the latter involves removing the hydrochloride salt to create a form that can be smoked. Cocaine exerts its...