Lexikon

active transport is the pumping of ions or molecules across a cell membrane with the help of special enzymes, the so called transport proteins, which are built in or bound to the membrane of the cell. Active transport is going into the opposite direction than simple diffusion. While diffusion is a spontaneous process driven by the concentration-difference between two sides of the cell membrane. Molecules or ions are actively transported into the opposite direction (toward the higher concentration side of the memebrane) than by diffusion, so that active transport requires energy.

Active transport in the cells is able to pump molecules through membranes into the higher concentration space, e.g. more and more hydrogen ions into the stomach to reach a very acidic pH value necessary for digestion.

Nutrient uptake is ensured by active trasnport, even if the nutrient ions and molecules are in very low concentration outside the cell.

Ion pumps create charge differences and charge gradients in cell organelles.

Active transport is able to restrict the diffusion of hazardous or any unwanted ions and molecules into the cell.

Active transport may happen by direct energy uptake with the help of the transmembrane enzymes transporting the ions and molecules and having ATP-ase activity at the same time. The other mechanism of molecular trasport utilises the electrochemical potential difference, which is created by pumping ions (by energy consuming active transport) out of cells.

Some toxins e.g. digitalis inhibit the active transport of the cells.

impact of transportation-related activities on the environment, in particular, those impacts dealing with air pollution, noise, displacement of people and businesses, disruption of wildlife habitats, and overall growth-inducing effects.

gene transfer may be carried out by the following mediators:

• Gene transfer by liposomes

• DNA transfer in the form of a calciumphosphate complex

• Transfection: the introduction of foreign DNA into a host cell by viral or bacterial infection.

• Gene transfer by virus: incorporation of new DNA into and organism's cells, usually by a vector such as a modified virus.

transformation is a process by which the genetic material carried by an individual cell is altered by incorporation of exogenous DNA into its genome.

granulometry (effective hydrodynamic radius, m): the parameter of interest for particle size distribution The particle size distribution is needed in order to decide which route of administration is most appropriate for animal toxicity studies (acute toxicity and repeated dose toxicity).

The different particle sizes defined in EN 481 document1 are:

· inhalable fraction: mass fraction of particles that can be inhaled by nose and mouth;

· thoracic fraction: mass fraction of particles that passes the larynx;

· respirable fraction: mass fraction of particles that reaches the alveoli.

The determination of the particle size fractions is used to assess the possible health effects resulting from inhalation of airborne particles in the workplace.

a company which submits registration information to the Agency on behalf of other members of a joint registration. The information submitted by the lead registrant concerns classification and labelling, study summaries, test proposals and, if necessary, indication which of the information was reviewed by an assessor. If the members of the joint registration so decide, the lead registrant may also submit information on safe use and the CSR on behalf of the others. After the lead registrant submits the information, the other members of the joint registration submit the remaining information individually. (Source: REACH Glossary)

nuclear transfer is a type of cloning, a laboratory procedure in which a cell's nucleus is removed and placed into an oocyte with its own nucleus removed so the genetic information from the donor nucleus controls the resulting cell. Such cells can be induced to form embryos. This process was used to create the cloned sheep "Dolly".

polychlorinated dibenzofurans (PCDFs) are a group of halogenated organic componunds with a furane skeleton and chlor substituents different in numer. PCDFs occur as by-products in the manufacture of chlorinated organic substances, in the incineration of chlorine-containing substances such as PVC, in the bleaching of paper, and also from natural sources such as volcanoes and forest fires. Somilar to polychlorinated dibenzodioxins (PCDDs), they have been shown to bioaccumulate in humans and and animals, are known toxic, mutagenic, carcinogenic and reprotoxic.

polychlorinated dibenzodioxins (PCDDs), or simply dioxins, are a group of halogenated organic componunds with a dioxin skeleton and chlor substituents different in numer. Members of the PCDD family have been shown to bioaccumulate in humans and and animals, are known toxic, mutagenic, carcinogenic and reprotoxic. Similar group of toxicants are the the polychlorinated dibenzofurans (PCDFs). Dioxins occur as by-products in the manufacture of chlorinated organic substances, in the incineration of chlorine-containing substances such as PVC, in the bleaching of paper, and also from natural sources such as volcanoes and forest fires.

transgenic animals may be developed for a wide range of purposes. Some of the areas in which transgenic animals are important are: medical research, livestock improvement, pharming and xenotransplantation.

Pharming means the production of biologically active human proteins, diagnostics, monoclonal antobodies, and nutraceuticals.

is a measure of the electrical impedance of the skin, as a resistance value in kilo Ohms. A simple and robust method of assessing barrier function by recording the passage of ions through the skin using a Wheatstone bridge apparatus. It is used in skin corrosivity tests, the value of the eletrical impedance gives the damage of the skin disk used int he test treated by the test substance.

a transgenic animal is one that carries a foreign gene that has been deliberately inserted into its genome. The foreign gene is constructed using recombinant DNA methodology. In addition to the gene itself, the DNA usually includes other sequences to enable it

• to be incorporated into the DNA of the host and
• to be expressed correctly by the cells of the host.

Transgenic sheep and goats have been produced that express foreign proteins in their milk.

Transgenic chickens are now able to synthesize human proteins in the "white" of their eggs.

These animals should eventually prove to be valuable sources of proteins for human therapy.

In July 2000, researchers from the team that produced Dolly reported success in producing transgenic lambs in which the transgene had been inserted at a specific site in the genome and functioned well. [More]

Transgenic mice have provided the tools for exploring many biological questions.

An example: Normal mice cannot be infected with polio virus. They lack the cell-surface molecule that, in humans, serves as the receptor for the virus. So normal mice cannot serve as an inexpensive, easily-manipulated model for studying the disease. However, transgenic mice expressing the human gene for the polio virus receptor can be infected by polio virus and even develop paralysis and other pathological changes characteristic of the disease in humans.

Two methods of producing transgenic mice are widely used:

• transforming embryonic stem cells (ES cells) growing in tissue culture with the desired DNA;
• injecting the desired gene into the pronucleus of a fertilized mouse egg.

Source: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/TransgenicAnimals.html

Xenotransplantation

Transplant organs may soon come from transgenic animals. Patients die every year for lack of a replacement heart, liver, or kidney. For example, about 5,000 organs are needed each year in the United Kingdom alone. Transgenic pigs may provide the transplant organs needed to alleviate the shortfall. Currently, xenotransplantation is hampered by a pig protein that can cause donor rejection but research is underway to remove the pig protein and replace it with a human protein.

Nutritional supplements and pharmaceuticals

Milk-producing transgenic animals are especially useful for medicines.
Products such as insulin, growth hormone, and blood anti-clotting factors may soon be or have already been obtained from the milk of transgenic cows, sheep, or goats. Research is also underway to manufacture milk through transgenesis for treatment of debilitating diseases such as phenylketonuria (PKU), hereditary emphysema, and cystic fibrosis.

In 1997, the first transgenic cow, Rosie, produced human protein-enriched milk at 2.4 grams per litre. This transgenic milk is a more nutritionally balanced product than natural bovine milk and could be given to babies or the elderly with special nutritional or digestive needs. Rosie’s milk contains the human gene alpha-lactalbumin. A transgenic cow exists that produces a substance to help human red cells grow.

Human gene therapy

Human gene therapy involves adding a normal copy of a gene (transgene) to the genome of a person carrying defective copies of the gene. The potential for treatments for the 5,000 named genetic diseases is huge and transgenic animals could play a role. For example, the Virtanen Institute in Finland produced a calf with a gene that makes the substance that promotes the growth of red cells in humans.

transgenic animals may be produced as disease models, meaning genetically manipulated animals, which exhibit disease symptoms so that effective treatment can be studied. For example, Harvard scientists made a major scientific breakthrough when they received a U.S. patent (the company DuPont holds exclusive rights to its use) for a genetically engineered mouse, called OncoMouse® or the Harvard mouse, carrying a gene that promotes the development of various human cancers.

transgenic organism is an experimentally produced organism in which DNA has been artificially introduced and incorporated into the organism's germ line.

the term "transitional waters" first came to prominence in 2000 with the publication of the Water Framework Directive of the European Communities [European Communities, 2000. Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official Journal of the European Communities 43 (L327), 75 pp.], where "transitional waters" are defined as "bodies of surface water in the vicinity of river mouths which are partially saline in character as a result of their proximity to coastal waters but which are substantially influenced by freshwater flows".

The term transitional waters should be refined by differentiation between and definition of tidal estuaries and non-tidal brackish water lagoons, as well as the incorporation of fjords, fjards, river mouths, deltas, rias and lagoons as well as the more classical estuaries.