4-D printing
4D Printing, is a new process for printing customizable smart materials. 4D Printing entails multi-material prints with the added capability of shape-transformation from one state to another, directly off the print-bed. This technique offers a streamlined path from idea to full functionality built directly into the materials, including; actuation, sensing and material logic. Potential applications include; robotics-like behavior without the reliance on complex electro-mechanical devices as well as adaptive products, garments or mechanisms that respond to user-demands and fluctuating environments.
With a single multi-material print, a product or mechanism can transform from any 1D strand into 3D shape, 2D surface into 3D shape or morph from one 3D shape into another. Using only water, heat, light or other simple energy input, this technique offers adaptability and dynamic response for structures and systems of all sizes.
Drug resistant Tuberculosis
A person with active TB disease has drug resistant TB if the TB bacteria that the person is infected with, will not respond to, and are resistant to, at least one of the main TB drugs.
Drug susceptible TB is the opposite of drug resistant TB. If someone is infected with TB bacteria that are fully susceptible, it means that all of the TB drugs will be effective so long as they are taken properly. It still means that several drugs need to be taken together to provide effective TB treatment. Drug susceptibility testing is how you find out which drugs will be effective against certain TB bacteria.
Drug resistant TB – how do you get it?
There are two ways that people get drug resistant TB.
Firstly, people get acquired drug resistant TB when their TB treatment is inadequate. This can be for a number of reasons, including the fact that patients fail to keep to proper TB treatment regimes. It can also be that the wrong TB drugs are prescribed, or sub standard TB drugs are used for treatment.
Secondly, transmitted or primary drug resistant TB, results from the direct transmission of drug resistant TB from one person to another. The occurrence and prevention of primary drug resistant TB has largely been neglected during the development of global TB control programs.
What are the main types of drug resistant TB?
There are two main types of drug resistant TB, MDR TB and XDR TB.
MDR (multi drug resistant) TB is the name given to TB when the bacteria that are causing it are resistant to at least isoniazid and rifampicin, two of the most effective TB drugs.
XDR TB (extensively drug resistant TB) is defined as strains resistant to at least rifampicin and isoniazid. This is in addition to strains being resistant to one of the fluoroquinolones, as well as resistant to at least one of the second line injectable TB drugs amikacin, kanamycin or capreomycin.
MDR TB and XDR TB do not respond to the standard six months of TB treatment with “first line” anti TB drugs. Treatment for them can take two years or more and requires treatment with other drugs that are less potent, more toxic and much more expensive. Worldwide only a few thousand patients with MDR TB and XDR TB are treated each year.
What other types of drug resistant TB are there?
A third type of drug resistant TB, variously referred to as totally drug resistant TB, XXDR TB or TDR TB has also now been detected. It is sometimes also referred to as extremely drug resistant TB, and it is extremely difficult, although not always totally impossible to treat.
High burden drug resistant TB countries
There are 27 TB drug resistant “high burden” countries. These are the 27 countries with the highest incidence of TB. They are also countries where there are at least 4,000 cases of MDR TB each year and/or at least 10% of newly registered TB cases are of MDR TB.
The 27 “high burden” countries are:
Armenia, Azerbaijan, Bangladesh, Belarus, Bulgaria, China, Democratic Republic of the Congo, Estonia, Ethiopia, Georgia, India, Indonesia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Myanmar, Nigeria, Pakistan, Philippines, Republic of Moldova, Russian Federation, South Africa, Tajikistan, Ukraine, Uzbekistan, Viet Nam.