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Totarol
Totarol is a naturally produced diterpene that is bioactive as totarol. It was first isolated by McDowell and Esterfield from the heartwood of ''Podocarpus totara'', a conifer tree found in New Zealand.Short, W. F.; Stromberg, H. ''J. Chem. Soc.'' 1937, 516-520 Podocarpus totara was investigated for unique molecules due to the tree's increased resistance to rotting. Recent studies have confirmed totarol's unique antimicrobial and therapeutic properties. Consequently, totarol is a candidate for a new source of drugs and has been the goal of numerous syntheses. Occurrence Although totarol was first isolated in ''Podocarpus totara'', totarol has also been identified in numerous other species of Podocarpaceae and Cupressaceae, with the majority found in the genus ''Podocarpus'' of the family Podocarpaceae and the subfamily Cupressoideae of the family Cupressaceae.Sharp, H.; Latif, Z.; Bartholomew, B.; Bright, C.; Jones, C. D.; Sarker, S. D.; Nash, R. "Totarol, totaradiol and ferrugi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Totarol Map
Totarol is a naturally produced diterpene that is bioactive as totarol. It was first isolated by McDowell and Esterfield from the heartwood of ''Podocarpus totara'', a conifer tree found in New Zealand.Short, W. F.; Stromberg, H. ''J. Chem. Soc.'' 1937, 516-520 Podocarpus totara was investigated for unique molecules due to the tree's increased resistance to rotting. Recent studies have confirmed totarol's unique antimicrobial and therapeutic properties. Consequently, totarol is a candidate for a new source of drugs and has been the goal of numerous syntheses. Occurrence Although totarol was first isolated in ''Podocarpus totara'', totarol has also been identified in numerous other species of Podocarpaceae and Cupressaceae, with the majority found in the genus ''Podocarpus'' of the family Podocarpaceae and the subfamily Cupressoideae of the family Cupressaceae.Sharp, H.; Latif, Z.; Bartholomew, B.; Bright, C.; Jones, C. D.; Sarker, S. D.; Nash, R. "Totarol, totaradiol and ferrug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma-Aldrich
Sigma-Aldrich (formally MilliporeSigma) is an American chemical, life science, and biotechnology company that is owned by the German chemical conglomerate Merck Group. Sigma-Aldrich was created in 1975 by the merger of Sigma Chemical Company and Aldrich Chemical Company. It grew through various acquisitions until it had over 9,600 employees and was listed on the Fortune 1000. The company is headquartered in St. Louis and has operations in approximately 40 countries. In 2015, the German chemical conglomerate Merck Group acquired Sigma-Aldrich for $17 billion. The company is currently a part of Merck's life science business and in combination with Merck's earlier acquired Millipore Corporation, Millipore, operates as MilliporeSigma. History Sigma Chemical Company of St. Louis and Aldrich Chemical Company of Milwaukee were both American specialty chemical companies when they merged in August 1975. The company grew throughout the 1980s and 1990s, with significant expansion in fac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acid-fast
Acid-fastness is a physical property of certain bacterial and eukaryotic cells, as well as some sub-cellular structures, specifically their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sample, these organisms can resist the acid and/or ethanol-based decolorization procedures common in many staining protocols, hence the name ''acid-fast''. The mechanisms of acid-fastness vary by species, although the most well-known example is in the genus '' Mycobacterium'', which includes the species responsible for tuberculosis and leprosy. The acid-fastness of ''Mycobacteria'' is due to the high mycolic acid content of their cell walls, which is responsible for the staining pattern of poor absorption followed by high retention. Some bacteria may also be partially acid-fast, such as '' Nocardia''. Acid-fast organisms are difficult to characterize using standard microbiological techniques, though they can be stained using concentrated dye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cough
A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three phases: an inhalation, a forced exhalation against a closed glottis, and a violent release of air from the lungs following opening of the glottis, usually accompanied by a distinctive sound. Frequent coughing usually indicates the presence of a disease. Many viruses and bacteria benefit, from an evolutionary perspective, by causing the host to cough, which helps to spread the disease to new hosts. Most of the time, irregular coughing is caused by a respiratory tract infection but can also be triggered by choking, smoking, air pollution, asthma, gastroesophageal reflux disease, post-nasal drip, chronic bronchitis, lung tumors, heart failure and medications such as angiotensin-converting-enzyme inhibitors (ACE inhibitors). Treatment should t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, coughing, chest tightness, and shortness of breath. These may occur a few times a day or a few times per week. Depending on the person, asthma symptoms may become worse at night or with exercise. Asthma is thought to be caused by a combination of genetic and environmental factors. Environmental factors include exposure to air pollution and allergens. Other potential triggers include medications such as aspirin and beta blockers. Diagnosis is usually based on the pattern of symptoms, response to therapy over time, and spirometry lung function testing. Asthma is classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate. It may also be classified as atopic or non-atopic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fever
Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single agreed-upon upper limit for normal temperature with sources using values between in humans. The increase in set point triggers increased muscle tone, muscle contractions and causes a feeling of cold or chills. This results in greater heat production and efforts to conserve heat. When the set point temperature returns to normal, a person feels hot, becomes Flushing (physiology), flushed, and may begin to Perspiration, sweat. Rarely a fever may trigger a febrile seizure, with this being more common in young children. Fevers do not typically go higher than . A fever can be caused by many medical conditions ranging from non-serious to life-threatening. This includes viral infection, viral, bacterial infection, bacterial, and parasitic infect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Māori Culture
Māori culture () is the customs, cultural practices, and beliefs of the indigenous Māori people of New Zealand. It originated from, and is still part of, Polynesians, Eastern Polynesian culture. Māori culture forms a distinctive part of Culture of New Zealand, New Zealand culture and, due to a large diaspora and the incorporation of Māori motifs into popular culture, it is found throughout the world. Within Māoridom, and to a lesser extent throughout New Zealand as a whole, the word is often used as an approximate synonym for Māori culture, the Māori language, Māori-language suffix being roughly equivalent to the qualitative noun-ending ''-ness'' in English. has also been translated as "[a] Māori way of life." Four distinct but overlapping cultural eras have contributed Māori history, historically to Māori culture: * before Māori culture had differentiated itself from other Polynesian cultures (Archaic period) * before widespread European contact (Classic period) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid Bilayer
The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cells. The cell membranes of almost all organisms and many viruses are made of a lipid bilayer, as are the nuclear membrane surrounding the cell nucleus, and membranes of the membrane-bound organelles in the cell. The lipid bilayer is the barrier that keeps ions, proteins and other molecules where they are needed and prevents them from diffusing into areas where they should not be. Lipid bilayers are ideally suited to this role, even though they are only a few nanometers in width, because they are impermeable to most water-soluble (hydrophilic) molecules. Bilayers are particularly impermeable to ions, which allows cells to regulate salt concentrations and pH by transporting ions across their membranes using proteins called ion pumps. Biological bilayers are usually composed of amphiphilic phosphol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokinesis
Cytokinesis () is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meiosis. During cytokinesis the spindle apparatus partitions and transports duplicated chromatids into the cytoplasm of the separating daughter cells. It thereby ensures that chromosome number and complement are maintained from one generation to the next and that, except in special cases, the daughter cells will be functional copies of the parent cell. After the completion of the telophase and cytokinesis, each daughter cell enters the interphase of the cell cycle. Particular functions demand various deviations from the process of symmetrical cytokinesis; for example in oogenesis in animals the ovum takes almost all the cytoplasm and organelles. This leaves very little for the resulting polar bodies, which in most species die without function, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaerobic Organism
An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment. Anaerobes may be unicellular (e.g. protozoans, bacteria) or multicellular. Most fungi are obligate aerobes, requiring oxygen to survive. However, some species, such as the Chytridiomycota that reside in the rumen of cattle, are obligate anaerobes; for these species, anaerobic respiration is used because oxygen will disrupt their metabolism or kill them. Deep waters of the ocean are a common anoxic environment. First observation In his letter of 14 June 1680 to The Royal Society, Antonie van Leeuwenhoek described an experiment he carried out by filling two identical glass tubes about halfway with crushed pepper powder, to which some clean rain water was added. Van Leeuwenhoek sealed one of the glass tubes using a flame an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penicillin Binding Proteins
Penicillin-binding proteins (PBPs) are a group of proteins that are characterized by their affinity for and binding of penicillin. They are a normal constituent of many bacteria; the name just reflects the way by which the protein was discovered. All β-lactam antibiotics (except for tabtoxinine-β-lactam, which inhibits glutamine synthetase) bind to PBPs, which are essential for bacterial cell wall synthesis. PBPs are members of a subgroup of enzymes called transpeptidases. Specifically, PBPs are DD-transpeptidases. Diversity There are a large number of PBPs, usually several in each organism, and they are found as both membrane-bound and cytoplasmic proteins. For example, Spratt (1977) reports that six different PBPs are routinely detected in all strains of ''E. coli'' ranging in molecular weight from 40,000 to 91,000. The different PBPs occur in different numbers per cell and have varied affinities for penicillin. The PBPs are usually broadly classified into high-molecular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penicillin
Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from ''Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum using deep tank fermentation and then purified. A number of natural penicillins have been discovered, but only two purified compounds are in clinical use: penicillin G (intramuscular or intravenous use) and penicillin V (given by mouth). Penicillins were among the first medications to be effective against many bacterial infections caused by staphylococci and streptococci. They are still widely used today for different bacterial infections, though many types of bacteria have developed resistance following extensive use. 10% of the population claims penicillin allergies but because the frequency of positive skin test results decreases by 10% with each year of avoidance, 90% of these patients can tolerate penicillin. Additionally, those with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
