Beginner Medical English

A Reference Handbook for Mongolian Students and Healthcare Professionals (DOWNLOAD)

Medical Terminology

ONLINE LESSONS for Healthcare Professionals in Mongolia

Human Anatomy and Physiology

by Dr. Bruce Forciea, 2012 (DOWNLOAD)

Cells: Molecules and Mechanisms

University Cell and Molecular Biology textbook (DOWNLOAD)

Wednesday, October 24, 2012

NEWS: Brain Police: Stem cells’ fecund daughters also boss other cells around

Originally posted by Stanford School of Medicine on Oct 22, 2012
by Bruce Goldman

Neural stem cells get plenty of good press, and understandably so. They’re the matriarchal cells of the brain, from which spring all except one type of cell populating our most highly regarded (at least by itself) organ. They can remain in their primordial state for decades, languidly dividing just enough to replace their own numbers. Alternatively, they can spawn daughter cells that depart from the primordial state.

It’s the matriarchs’ daughters – so-called neural progenitor cells – that embark on committed differentiation pathways giving rise to nerve cells and other key brain cells. Given that lofty ambition, it’s not surprising that neural progenitor cells divide much more rapidly than their parents do, outnumbering neural stem cells probably by 1,000 to 1 or more.

It turns out that neural progenitors can do more than breed. They’re excellent managers, too. In a new Nature Neuroscience study that I describe in this news release, Stanford neuroscientist Tony Wyss-Coray, PhD, and his colleagues demonstrated that neural progenitor cells squirt out substances regulating the behavior of the one type of brain cell that doesn’t call them grandma.
  • Microglia normally are distributed throughout the brain – rather small, quiescent cells sprouting long, skinny projections that meekly but efficiently survey large areas that, taken together, cover the entire brain. But if this surveillance reveals signs of a disturbance, such as injury or infection, the microglia whirl into action. They begin proliferating and their puny bodies puff up, metamorphosing from mild-mannered Clark Kent-like reporters to buffed Supermen who fly to the scene of trouble, where they secrete substances that can throttle bad actors or call in reinforcements. Within these activated cells, internal garbage disposals called lysosomes form in large numbers and start whirring, ready to make mincemeat out of pathogens or cellular debris.

Wyss-Coray’s group showed, in rodents, that specific factors secreted by neural progenitor cells get microglia pumped. The discovery is significant considering that in the two places in the adult mammalian brain (including the human variety) where neural stem and progenitor cells reside, they’re typically closely associated with an entourage of microglia.

Now we know who’s boss. And we may have a clue about why stem-cell transplants seem to improve brain function, even though the stem cells don’t actually engraft very well.

Word List:
matriarchal: controlled by women rather than men; passing power, property, etc. from mother to daughter rather than from father to son
primordial: very basic
languid: moving slowly in an elegant manner, not needing energy or effort
to spawn: to cause something to develop or be produced
to embark on: to start to do something new or difficult
to give rise: to cause something to happen or exist
lofty: very high and impressive
to squirt: to force liquid, gas, etc. in a thin fast stream through a narrow opening; to be forced out of a narrow opening in this way
quiescent: quiet; not active; not developing, especially when this is probably only a temporary state
to sprout: to appear; to develop something, especially in large numbers; to start to grow something; to start to grow on somebody/something
to whirl: to move, or make somebody/something move, around quickly in a circle or in a particular direction
to proliferate: to increase rapidly in number or amount
puny: small and weak
to puff up: to swell or to make something swell
metamorphosis: a process in which somebody/something changes completely into something different
to secrete: to produce a liquid substance
to throttle somebody: to attack or kill somebody by squeezing their throat in order to stop them from breathing
garbage disposal: a machine connected to the waste pipe of a kitchen sink, for cutting food waste into small pieces
entourage: a group of people who travel with an important person
to engraft: to incorporate in a firm or permanent way; implant:

Tuesday, October 16, 2012

MedTerm: DiGeorge syndrome

Originally posted on MedTerms.com/MedicineNet.com

DiGeorge syndrome: A genetic disorder characterized by hypocalcemia, immunodeficiency, and congenital heart disease:
  • Hypocalcemia (low calcium levels in the blood) due to hypoplasia (underdevelopment) of the parathyroid glands that are needed to control calcium;
  • Immunodeficiency due to hypoplasia (underdevelopment) of the thymus (an organ behind the breastbone needed for the maturation of lymphocytes into T cells); and
  • Congenital heart disease with defects of the outflow tracts (the pulmonary artery and aorta) from the heart. Next to Down syndrome, DiGeorge syndrome is the most common genetic cause of congenital heart disease.
DiGeorge syndrome is caused by a microdeletion in chromosome band 22q11.2. The key gene that is lost is Tbx-1, a master control gene that regulates other genes required for the connection of the heart with the blood circulation. Tbx-1 also controls genes involved in the development of the parathyroid and thymus glands and the shape of the face.

Babies with DiGeorge syndrome are highly susceptible to infections and, in the past, usually died by age 2. Transplantation of thymus tissue can restore normal immune function to infants with DiGeorge syndrome.

However, bone marrow cells babies with DiGeorge syndrome can spontaneously transform into rogue T cells that attack and reject the thymus transplant. An immunosuppressant drug called Thymoglobulin (antithymocyte globulin), which selectively targets T cells, given prior to the transplant has been found to quash the rogue T cells and permit a successful thymus transplant.

The syndrome is named for the American pediatric endocrinologist Angelo DiGeorge who worked at St. Christopher's Hospital in Philadelphia. Also known as hypoplasia of the thymus and parathyroids and as third and fourth pharyngeal pouch syndrome.

Pronunciation Practice:
hypocalcemia = цусны кальци багасах
hypoplasia = эд эрхтэний дутуу хөгжил
congenital = төрөлхийн
parathyroid = пара бамбайн булчирхай
immunodeficiency = дархлалын хомсдол
thymus = тимус
lymphocyte = тунгалаг эс, лимфоцит
pulmonary = уушгины
syndrome = хам шинж
immunosuppressant = дархлал устгагч