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Neoplasms: New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms.

Cancer

JoVE 10987

Cancers arise due to mutations in genes involved in the regulation of cell division, which leads to unrestricted cell proliferation. Modern science and medicine have made great strides in the understanding and treatment of cancer, including eradicating cancer in some patients. However, there is still no cure for cancer. This is largely due to the fact that cancer is a large group of many diseases. Tumors may result in a case where two people have the same mutations in an oncogene or tumor suppressor gene. Initially, the tumors may be very similar. However, the uncontrolled cell division results in new random mutations. As the tumor cells continue to divide, they become more varied. As a result, the two tumors will grow at different rates and undergo angiogenesis and metastasis at different times. The two cancers become so distinct from one another that they will not respond in the same way to the same therapy. This demonstrates why even a particular type of cancer, breast cancer, for example, can be a myriad of different cancers, each disease case with its unique properties, potentially requiring unique treatment approaches. As such, new cancer research and clinical trials focus on tailoring therapeutic approaches specifically for each patient’s genomic and molecular landscape. This is called personalized medicine. On the other hand, chemotherapy

 Core: Biology

Longitudinal Research

JoVE 11023

Sometimes we want to see how people change over time, as in studies of human development and lifespan. When we test the same group of individuals repeatedly over an extended period of time, we are conducting longitudinal research. Longitudinal research is a research design in which data-gathering is administered repeatedly over an extended period of time. For example, we may…

 Core: Psychology

Cell Division- Concept

JoVE 10571

Cell division is fundamental to all living organisms and required for growth and development. As an essential means of reproduction for all living things, cell division allows organisms to transfer their genetic material to their offspring. For a unicellular organism, cellular division generates a completely new organism. For multicellular organisms, cellular division produces new cells for…

 Lab Bio

What is the Cell Cycle?

JoVE 10757

The cell cycle refers to the sequence of events occurring throughout a typical cell’s life. In eukaryotic cells, the somatic cell cycle has two stages: interphase and the mitotic phase. During interphase, the cell grows, performs its basic metabolic functions, copies its DNA, and prepares for mitotic cell division. Then, during mitosis and cytokinesis, the cell divides its nuclear and cytoplasmic materials, respectively. This generates two daughter cells that are identical to the original parent cell. The cell cycle is essential for the growth of the organism, replacement of damaged cells, and regeneration of aged cells. Cancer is the result of uncontrolled cell division sparked by a gene mutation. There are three major checkpoints in the eukaryotic cell cycle. At each checkpoint, the progression to the next cell cycle stage can be halted until conditions are more favorable. The G1 checkpoint is the first of these, where a cell’s size, energy, nutrients, DNA quality, and other external factors are evaluated. If the cell is deemed inadequate, it does not continue to the S phase of interphase. The G2 checkpoint is the second checkpoint. Here, the cell ensures that all of the DNA has been replicated and is not damaged before entering mitosis. If any DNA damage is detected that cannot be repaired, the cell may undergo apoptosis, or

 Core: Biology

Pelvic Exam II: Speculum Exam

JoVE 10141

Source:


Alexandra Duncan, GTA, Praxis Clinical, New Haven, CT


Tiffany Cook, GTA, Praxis Clinical, New Haven, CT


Jaideep S. Talwalkar, MD, Internal Medicine and Pediatrics, Yale School of Medicine, New Haven, CT


Providing…

 Physical Examinations II

Lymph Node Exam

JoVE 10061

Source: Richard Glickman-Simon, MD, Assistant Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine, MA


The lymphatic system has two main functions: to return extracellular fluid back to the venous circulation and to expose antigenic substances to the immune system. As the collected fluid passes …

 Physical Examinations II

Epigenetic Regulation

JoVE 10803

Epigenetic mechanisms play an essential role in healthy development. Conversely, precisely regulated epigenetic mechanisms are disrupted in diseases like cancer.

In most mammals, females have two X chromosomes (XX) while males have an X and a Y chromosome (XY). The X chromosome contains significantly more genes than the Y chromosome. Therefore, to prevent an excess of X chromosome-linked gene expression in females, one of the two X chromosomes is randomly silenced during early development. This process, called X-chromosome inactivation, is regulated by DNA methylation. Scientists have found greater DNA methylation at gene promoter sites on the inactive X chromosome than its active counterpart. DNA methylation prevents the transcription machinery from attaching to the promoter region, thus inhibiting gene transcription. Abnormal DNA methylation plays an important role in cancer. The promoter region of most genes contains stretches of cytosine and guanine nucleotides linked by a phosphate group. These regions are called CpG islands. In healthy cells, CpG islands are not methylated. However, in cancer cells, CpG islands in the promoter regions of tumor suppressor genes or cell cycle regulators are excessively methylated. Methylation turns off the expression of these genes, allowing cancer cells to divide rapidly and uncontrollably.

 Core: Biology

Autocrine Signaling

JoVE 10973

Secreted signals can act on a variety of target cells. In some cases, the cell that secretes a signal also detects and responds to the signaling molecule it produces; this is called Autocrine Signaling.

Under normal physiological conditions, autocrine signaling is important for homeostasis. This process is well characterized in the macrophages of the immune system. Macrophages secrete a variety of signals including the cytokine Interleukin-1, IL-1. The secreting macrophages also possess membrane receptors for IL-1 that, when bound, can activate an intracellular signaling cascade. The resulting intracellular signals trigger the secretion of additional cytokines including more IL-1 from the target cell. Though IL-1 secreted by these macrophages can also bind to receptors on other cells and cell types, binding to the signaling cell is important in the regulation of signal production. Autocrine signaling is also a major mechanism of cancer cell proliferation. Cancerous cells secrete a variety of growth signals to themselves, through autocrine signaling, and to nearby tissues. For example, progesterone appears to act in an autocrine manner in breast cancer, whereby progesterone binds to progesterone receptors on the signaling cell, stimulating the action of growth-promoting genes. Autocrine signaling can also play a role in the development of skin cancer by stim

 Core: Biology

Cause and Effect

JoVE 11031

While variables are sometimes correlated because one does cause the other, it could also be that some other factor, a confounding variable, is actually causing the systematic movement in our variables of interest. For instance, as sales in ice cream increase, so does the overall rate of crime. Is it possible that indulging in your favorite flavor of ice cream could send you on a crime spree?…

 Core: Psychology

Cell-mediated Immune Responses

JoVE 10896

The cell-mediated immune system is the host’s primary response against invasive bacteria and viruses that cause intracellular infections. It is also essential for fighting against and destroying cancer cells. Furthermore, the cell-mediated immune system plays a role in the rejection of organ transplants or graft tissue.

Phagocytic cells of the innate immune system, such as macrophages or dendritic cells, are the first to recognize a foreign particle. These cells engulf the foreign particle and digest it. Small molecules of the foreign particle, called antigens, remain intact and are presented at the surface of the phagocytic cell. The presentation is facilitated by proteins of the major histocompatibility complex (MHC), which binds the antigen and protrude from the cell. The phagocytic cell is therefore also called an antigen presenting cell (APC). The MHC-antigen complex activates cells of the adaptive immune system, which eventually fight the source of the foreign particle. T cells are a type of lymphocyte that are named after their location of maturation—the thymus. In the thymus, precursor T cells differentiate into two main types, CD4+ and CD8+ T cells. These cell types are named after the surface receptor that determines the cell’s function. All T cells carry T-cell receptors, but the coreceptor CD4

 Core: Biology
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