Fate mapping is a technique that is used to show how a cell or tissue moves and what it will become during normal development. Fate mapping was developed by Walter Vogt as a means by which to trace the development of specific regions of the early embryo. To do this, Vogt used agar chips impregnated with vital dyes.fate map is a representation of the developmental history of each cell in the body of an adult organism. Thus, a fate map traces the products of each mitosis from the single-celled zygote to the multi-celled adult. The process of fate mapping was developed by Walter Vogt.
As a human embryo develops, its cells become progressively restricted in the types of specialized cells that they can produce. Inner cell mass (ICM) cells of the blastocyst can make any type of body cell. Gastrula-stage cells can give rise to the cells of a given germ layer. Later, cells become even more restricted. For example, the pancreatic bud of the endoderm layer can only make the cells of the pancreas.
Venipuncture or venepuncture (also known as phlebotomy, venesection, blood draw, drawing blood or taking blood) is the process of obtaining a sample of venous blood. Usually a 5 ml to 25 ml sample of blood is adequate depending on what blood tests have been requested. In many circumstances it will be done by a phlebotomist, although medical practitioners, some EMTs, paramedics, other nursing staff are also trained to take blood.
Blood is most commonly obtained from the median cubital vein, on the anterior forearm (the side within the fold of the elbow). This vein lies close to the surface of the skin, and there is not a large nerve supply.
Minute quantities of blood may be taken by fingersticks sampling and collected from infants by means of a heel stick or from scalp veins with a butterfly needle.
Phlebotomy (incision into a vein) is also the treatment of certain diseases such as hemochromatosis and primary and secondary polycythemia.
The taste centers are in the cortex and in the thalamus of the brain. The organ of taste is the tongue. The surface of the tongue is covered with thousands of tiny fronds or papillae, which give it a velvety sheen. The taste buds, the primary organs of taste, are found within these papillae. There are four type of papillae-filiform, fungiform, foliate and vallate. Filiform and fungiform papillae are found on the front half of the tongue, and foliate papillae at the back. Filiform are threadlike in shape and more numerous than the mushroom-shaped fungiform type. Vallate papillae form a V across the back of the tongue. The base of the tongue is devoid of papillae, but is covered with nodules of lymphoid tissue, which make up the lingual tonsil. A taste bud consists of taste cells, with hairs that project into the moats surrounding the papillae, supporting cells and nerves. The salivary glands are connected by nerves to the taste buds. Stimulation of the taste buds stimulates the salivary glands to produce saliva.
UC San Francisco presents Mini Medical School. In this edition, Didier Stainer, UCSF professor of Biochemistry and Biophysics explores what role incorrect development of the heart and other organs can play in such conditions as sudden death in young athletes, cancer and some birth defects, and how current research can contribute to future gene therapy. Series: UCSF Mini Medical School for the Public.
Myomectomy refers to the surgical removal of uterine fibroids, also known as myomas. In contrast to a hysterectomy the uterus remains preserved and the woman retains her reproductive potential.
The presence of a fibroid does not mean that it needs to be removed. Removal is called for when the fibroid causes pain, abnormal bleeding, or pressure.
A myomectomy can be performed in a number of ways, depending on the location and number of lesions and the experience of the surgeon. Typically a myomectomy is performed via a laparotomy, the uterus incised, and the lesion(s) removed. A fibroid that is located in a submucous position may be accessible to hysteroscopic removal. In some instances also laparoscopy can be utilized to extirpate fibroids.
Complications of the surgery include the possibility of significant blood loss leading to a blood transfusion, the risk of adhesion or scar formation around the uterus, and the possible need later to deliver via cesarean section. Development of new fibroids will be seen in 42-55% of patients undergoing a myomectomy
Warfarin (also known under the brand names Coumadin, Jantoven, Marevan, and Waran) is an anticoagulant. It is named after the Wisconsin Alumni Research Foundation, which sponsored its development. It was initially marketed as a pesticide against rats and mice, and is still popular for this purpose, although more potent poisons such as brodifacoum have since been developed. A few years after its introduction, warfarin was found to be effective and relatively safe for preventing thrombosis and embolism (abnormal formation and migration of blood clots) in many disorders. It was approved for use a medication in the early 1950s, and has remained popular ever since; warfarin is the most widely prescribed anticoagulant drug in North America.Despite its effectiveness, treatment with warfarin has several shortcomings. Many commonly used medications interact with warfarin, and its activity has to be monitored by frequent blood testing for the international normalized ratio (INR) to ensure an adequate yet safe dose is taken.
Warfarin is a synthetic derivative of coumarin, a chemical found naturally in many plants, notably woodruff (Galium odoratum, Rubiaceae), and at lower levels in licorice, lavender, and various other species. Warfarin and related coumarins decrease blood coagulation by inhibiting vitamin K epoxide reductase, an enzyme that recycles oxidated vitamin K to its reduced form after it has participated in the carboxylation of several blood coagulation proteins, mainly prothrombin and factor VII. For this reason, drugs in this class are also referred to as vitamin K antagonists.
The early 1920s saw the outbreak of a previously unrecognized disease of cattle in the northern United States and Canada. Cattle would die of uncontrollable bleeding from very minor injuries, or sometimes drop dead of internal hemorrhage with no external signs of injury. In 1921, Frank Schofield, a Canadian veterinarian, determined that the cattle were ingesting moldy silage made from sweet clover that functioned as a potent anticoagulant. In 1929, North Dakota veterinarian Dr L.M. Roderick demonstrated that the condition was due to a lack of functioning prothrombin.
The identity of the anticoagulant substance in moldy sweet clover remained a mystery until 1940 when Karl Paul Link and his student Harold Campbell, chemists working at the University of Wisconsin, determined that it was the coumarin derivative 4-hydroxycoumarin. Over the next few years, numerous similar chemicals were found to have the same anticoagulant properties. The first of these to be widely commercialized was dicoumarol, patented in 1941. Link continued working on developing more potent coumarin-based anticoagulants for use as rodent poisons, resulting in warfarin in 1948. (The name warfarin stems from the acronym WARF, for Wisconsin Alumni Research Foundation + the ending -arin indicating its link with coumarin.) Warfarin was first registered for use as a rodenticide in the US in 1948, and was immediately popular; although it was developed by Link, the WARF financially supported the research and was granted the patent.
After an incident in 1951, where an army inductee unsuccessfully attempted suicide with warfarin and recovered fully,studies began in the use of warfarin as a therapeutic anticoagulant. It was found to be generally superior to dicoumarol, and in 1954 was approved for medical use in humans. A famous early recipient of warfarin was US president Dwight Eisenhower, who was prescribed the drug after having a heart attack in 1955.
The exact mechanism of action remained unknown until it was demonstrated, in 1978, that warfarin inhibited the enzyme epoxide reductase and hence interfered with vitamin K metabolism.
A 2003 theory posits that warfarin was used by a conspiracy of Lavrenty Beria, Nikita Khrushchev and others to poison Soviet leader Joseph Stalin. Warfarin is tasteless and colorless, and produces symptoms similar to those that Stalin exhibited.
Therapeutic uses
Warfarin is prescribed to people with an increased tendency for thrombosis or as secondary prophylaxis (prevention of further episodes) in those individuals that have already formed a blood clot (thrombus). Warfarin treatment can help prevent formation of future blood clots and help reduce the risk of embolism (migration of a thrombus to a spot where it blocks blood supply to a vital organ). Common clinical indications for warfarin use are atrial fibrillation, the presence of artificial heart valves, deep venous thrombosis, pulmonary embolism, antiphospholipid syndrome and, occasionally, after myocardial infarction.
Dosing of warfarin is complicated by the fact that it is known to interact with many commonly-used medications and even with chemicals that may be present in certain foods. These interactions may enhance or reduce warfarin's anticoagulation effect. In order to optimize the therapeutic effect without risking dangerous side effects such as bleeding, close monitoring of the degree of anticoagulation is required by blood testing (INR). During the initial stage of treatment, checking may be required daily; intervals between tests can be lengthened if the patient manages stable therapeutic INR levels on an unchanged warfarin dose.
When initiating warfarin therapy ("warfarinization"), the doctor will decide how strong the anticoagulant therapy needs to be. The target INR level will vary from case to case depending on the clinical indicators, but tends to be 2–3 in most conditions. In particular, target INR may be 2.5–3.5 (or even 3.0–4.5) in patients with one or more mechanical heart valves.
In some countries, other coumarins are used instead of warfarin, such as acenocoumarol and phenprocoumon. These have a shorter (acenocoumarol) or longer (phenprocoumon) half-life, and are not completely interchangeable with warfarin. The oral anticoagulant ximelagatran (trade name Exanta) was expected to replace warfarin to a large degree when introduced; however, reports of hepatotoxicity (liver damage) prompted its manufacturer to withdraw it from further development. Other drugs offering the efficacy of warfarin without a need for monitoring, such as dabigatran and rivaroxaban, are under developmen
Eukaryotic cells are typically much larger than prokaryotes. They have a variety of internal membranes and structures, called organelles, and a cytoskeleton composed of microtubules, microfilaments, and intermediate filaments, which play an important role in defining the cell's organization and shape. Eukaryotic DNA is divided into several linear bundles called chromosomes, which are separated by a microtubular spindle during nuclear division.
Eukaryotic cells include a variety of membrane-bound structures, collectively referred to as the endomembrane system. Simple compartments, called vesicles or vacuoles, can form by budding off other membranes. Many cells ingest food and other materials through a process of endocytosis, where the outer membrane invaginates and then pinches off to form a vesicle. It is probable that most other membrane-bound organelles are ultimately derived from such vesicles.
The nucleus is surrounded by a double membrane (commonly referred to as a nuclear envelope), with pores that allow material to move in and out. Various tube- and sheet-like extensions of the nuclear membrane form what is called the endoplasmic reticulum or ER, which is involved in protein transport and maturation. It includes the Rough ER where ribosomes are attached, and the proteins they synthesize enter the interior space or lumen. Subsequently, they generally enter vesicles, which bud off from the Smooth ER. In most eukaryotes, this protein-carrying vesicles are released and further modified in stacks of flattened vesicles, called Golgi bodies or dictyosomes.
Vesicles may be specialized for various purposes.For instance, lysosomes contain enzymes that break down the contents of food vacuoles, and peroxisomes are used to break down peroxide, which is toxic otherwise. Many protozoa have contractile vacuoles, which collect and expel excess water, and extrusomes, which expel material used to deflect predators or capture prey. In multicellular organisms, hormones are often produced in vesicles. In higher plants, most of a cell's volume is taken up by a central vacuole, which primarily maintains its osmotic pressure.
Mitochondria and plastids
Mitochondria are organelles found in nearly all eukaryotes. They are surrounded by double membranes (known as the phospholipid bi-layer), the inner of which is folded into invaginations called cristae, where aerobic respiration takes place. They contain their own DNA and ribosomes and are only formed by the fission of other mitochondria. They are now generally held to have developed from endosymbiotic prokaryotes, probably proteobacteria. The few protozoa that lack mitochondria have been found to contain mitochondrion-derived organelles, such as hydrogenosomes and mitosomes.
Plants and various groups of algae also have plastids. Again, these have their own DNA and developed from endosymbiotes, in this case cyanobacteria. They usually take the form of chloroplasts, which like cyanobacteria contain chlorophyll and produce energy through photosynthesis. Others are involved in storing food. Although plastids likely had a single origin, not all plastid-containing groups are closely related. Instead, some eukaryotes have obtained them from others through secondary endosymbiosis or ingestion.
Endosymbiotic origins have also been proposed for the nucleus, for which see below, and for eukaryotic flagella, supposed to have developed from spirochaetes. This is not generally accepted, both from a lack of cytological evidence and difficulty in reconciling this with cellular reproduction.
