Related Concept Videos

Mechanism of Angiogenesis01:10

Mechanism of Angiogenesis

Blood vessel formation starts early during embryonic development, around day 7. In the extraembryonic yolk sac, mesodermal precursor cells called hemangioblast proliferate and differentiate into angioblast. Angioblasts express vascular endothelial growth factor receptor 2 or VEGFR2, which binds VEGF-A, a proangiogenic factor, guiding blood vessel formation. VEGF signaling promotes angioblasts to form a blood island in the developing embryo. Angioblasts further differentiate, giving rise to...
Mechanisms of Retrovirus-induced Cancers01:51

Mechanisms of Retrovirus-induced Cancers

Retroviruses are RNA viruses that have been shown to cause cancers in diverse species, including chickens, mice, cats, and monkeys. The RNA genomes of these viruses are first reverse-transcribed into single and then double-stranded DNA (dsDNA) copies. This dsDNA called proviral DNA then integrates into the host genome. Subsequently, the host cell transcribes the proviral DNA in concert with the chromosomal DNA. This leads to the production of viral RNA and proteins that assemble at the host...
National Nursing Organizations II01:30

National Nursing Organizations II

Nursing organizations play a vital role in representing nurses working in specialized clinical settings, such as the American Association of Critical-Care Nurses (AACN).
The AACN emphasizes a healthy work environment through six standards to achieve an optimal patient outcome. The standards are appropriate staffing, meaningful recognition, collaboration, authentic leadership, effective communication, and decision-making. In addition, AACN provides certification programs, webinars, journals, and...
National Nursing Organizations I01:26

National Nursing Organizations I

Nursing organizations assume a significant role in consistently developing the nursing profession through education, research studies, establishing practice standards, and reforming health policies. Typically, nursing organizations operate at the regional, national, and international levels. For example, the International Council of Nurses (ICN) represents more than 28 million nurses worldwide. In contrast, the American Nurses Association (ANA) is a membership organization representing nurses...
Preclinical Development: Overview01:28

Preclinical Development: Overview

Preclinical development consists of a series of tests that ensure the safety and efficacy of a new therapeutic compound before it is tested in humans. There are four main phases to this process. First, safety pharmacology tests are conducted to ensure the drug does not produce any acutely harmful effects. These tests examine parameters such as bronchoconstriction, cardiac dysrhythmias, blood pressure changes, and ataxia. Next, preliminary toxicological testing is performed to determine the...
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...