1.
Taxonomy (biology)
–
Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
2.
Bacteria
–
Bacteria constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods, Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology, There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants, Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of bodies and bacteria are responsible for the putrefaction stage in this process. In March 2013, data reported by researchers in October 2012, was published and it was suggested that bacteria thrive in the Mariana Trench, which with a depth of up to 11 kilometres is the deepest known part of the oceans. Other researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States. According to one of the researchers, You can find microbes everywhere—theyre extremely adaptable to conditions, the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial particularly in the gut flora. However several species of bacteria are pathogenic and cause diseases, including cholera, syphilis, anthrax, leprosy. The most common fatal diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year. In developed countries, antibiotics are used to treat infections and are also used in farming, making antibiotic resistance a growing problem. Once regarded as constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and these evolutionary domains are called Bacteria and Archaea. The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, for about 3 billion years, most organisms were microscopic, and bacteria and archaea were the dominant forms of life. In 2008, fossils of macroorganisms were discovered and named as the Francevillian biota, however, gene sequences can be used to reconstruct the bacterial phylogeny, and these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage. Bacteria were also involved in the second great evolutionary divergence, that of the archaea, here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea
3.
Louis Pasteur
–
Louis Pasteur was a French biologist, microbiologist and chemist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization. He is remembered for his breakthroughs in the causes and prevention of diseases. He reduced mortality from puerperal fever, and created the first vaccines for rabies and his medical discoveries provided direct support for the germ theory of disease and its application in clinical medicine. He is best known to the public for his invention of the technique of treating milk and wine to stop bacterial contamination. He is regarded as one of the three founders of bacteriology, together with Ferdinand Cohn and Robert Koch, and is popularly known as the father of microbiology. Pasteur was responsible for disproving the doctrine of spontaneous generation and he performed experiments that showed that without contamination, microorganisms could not develop. Under the auspices of the French Academy of Sciences, he demonstrated that in sterilized and sealed flasks nothing ever developed, although Pasteur was not the first to propose the germ theory, his experiments indicated its correctness and convinced most of Europe that it was true. Today, he is regarded as one of the fathers of germ theory. Pasteur also made significant discoveries in chemistry, most notably on the basis for the asymmetry of certain crystals. Early in his career, his investigation of tartaric acid resulted in the first resolution of what is now called optical isomers and his work led the way to the current understanding of a fundamental principle in the structure of organic compounds. He was the director of the Pasteur Institute, established in 1887, till his death, although Pasteur made groundbreaking experiments, his reputation became associated with various controversies. Historical reassessment of his notebook revealed that he practiced deception to overcome his rivals, Louis Pasteur was born on December 27,1822, in Dole, Jura, France, to a Catholic family of a poor tanner. He was the child of Jean-Joseph Pasteur and Jeanne-Etiennette Roqui. The family moved to Marnoz in 1826 and then to Arbois in 1827, Pasteur entered primary school in 1831. He was a student in his early years, and not particularly academic. He drew many pastels and portraits of his parents, friends, Pasteur attended secondary school at the Collège dArbois. In October 1838, he left for Paris to join the Pension Barbet, in 1839, he entered the Collège Royal de Besançon to study philosophy and earned his Bachelor of Letters degree in 1840. He was appointed a tutor at the Besançon college while continuing a degree course with special mathematics
4.
Scalpel
–
A scalpel, or lancet, is a small and extremely sharp bladed instrument used for surgery, anatomical dissection, and various arts and crafts. Scalpels may be disposable or re-usable. Re-usable scalpels can have permanently attached blades that can be sharpened or, more commonly, disposable scalpels usually have a plastic handle with an extensible blade and are used once, then the entire instrument is discarded. Scalpel blades are usually packed in sterile pouches but are also offered non-sterile. Double-edged scalpels are referred to as lancets, scalpel blades are usually made of hardened and tempered steel, stainless steel, or high carbon steel, in addition, titanium, ceramic, diamond and even obsidian knives are not uncommon. For example, when performing surgery under MRI guidance, steel blades are unusable, historically, the preferred material for surgical scalpels was silver, on account of its antimicrobial properties. Scalpel blades are also offered by manufacturers with a zirconium nitride-coated edge to improve sharpness. Others manufacture blades that are coated to enhance lubricity during a cut. Alternatives to scalpels in surgical applications include electrocautery and lasers, Surgical scalpels consist of two parts, a blade and a handle. The handles are often reusable, with the blades being replaceable, in medical applications, each blade is only used once. The handle is known as a B. P. handle, named after Charles Russell Bard and Morgan Parker. The handle of medical scalpels come in two basic types, the first is a flat handle used in the #3 and #4 handles. The #7 handle is more like a writing pen, rounded at the front. A #4 handle is larger than a #3, blades are manufactured with a corresponding fitment size so that they fit on only one size handle. The following table of blades is incomplete and some blades listed may work with handles not specified here, also called the dinner knife grip. This grip is best for initial incisions and larger cuts, best used for more accurate cuts with smaller blades and the #7 handle. The scalpel is held with the tips of the first and second fingers, care should be taken not to allow the handle to rest too far along the index finger as this promotes an unstable grip and cramped fingers. Graphical and model-making scalpels tend to have handles, with textured grips
5.
DNA
–
Deoxyribonucleic acid is a molecule that carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses. DNA and RNA are nucleic acids, alongside proteins, lipids and complex carbohydrates, most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA strands are termed polynucleotides since they are composed of simpler units called nucleotides. Each nucleotide is composed of one of four nitrogen-containing nucleobases—cytosine, guanine, adenine, or thymine —a sugar called deoxyribose, and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. The nitrogenous bases of the two polynucleotide strands are bound together, according to base pairing rules, with hydrogen bonds to make double-stranded DNA. The total amount of related DNA base pairs on Earth is estimated at 5.0 x 1037, in comparison the total mass of the biosphere has been estimated to be as much as 4 trillion tons of carbon. The DNA backbone is resistant to cleavage, and both strands of the double-stranded structure store the same biological information and this information is replicated as and when the two strands separate. A large part of DNA is non-coding, meaning that these sections do not serve as patterns for protein sequences, the two strands of DNA run in opposite directions to each other and are thus antiparallel. Attached to each sugar is one of four types of nucleobases and it is the sequence of these four nucleobases along the backbone that encodes biological information. RNA strands are created using DNA strands as a template in a process called transcription, under the genetic code, these RNA strands are translated to specify the sequence of amino acids within proteins in a process called translation. Within eukaryotic cells DNA is organized into structures called chromosomes. During cell division these chromosomes are duplicated in the process of DNA replication, eukaryotic organisms store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts. In contrast prokaryotes store their DNA only in the cytoplasm, within the eukaryotic chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed, DNA was first isolated by Friedrich Miescher in 1869. DNA is used by researchers as a tool to explore physical laws and theories, such as the ergodic theorem. The unique material properties of DNA have made it an attractive molecule for material scientists and engineers interested in micro-, among notable advances in this field are DNA origami and DNA-based hybrid materials. DNA is a polymer made from repeating units called nucleotides
6.
Protein
–
Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, a linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide, short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides, or sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bonds, the sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the code specifies 20 standard amino acids, however. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors, proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes. Once formed, proteins only exist for a period of time and are then degraded and recycled by the cells machinery through the process of protein turnover. A proteins lifespan is measured in terms of its half-life and covers a wide range and they can exist for minutes or years with an average lifespan of 1–2 days in mammalian cells. Abnormal and or misfolded proteins are degraded more rapidly due to being targeted for destruction or due to being unstable. Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms, many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. In animals, proteins are needed in the diet to provide the essential amino acids that cannot be synthesized, digestion breaks the proteins down for use in the metabolism. Methods commonly used to study structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonance. Most proteins consist of linear polymers built from series of up to 20 different L-α-amino acids, all proteinogenic amino acids possess common structural features, including an α-carbon to which an amino group, a carboxyl group, and a variable side chain are bonded. Only proline differs from this structure as it contains an unusual ring to the N-end amine group. The amino acids in a chain are linked by peptide bonds. Once linked in the chain, an individual amino acid is called a residue, and the linked series of carbon, nitrogen. The peptide bond has two forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar
7.
Streptococcus
–
Streptococcus is a genus of coccus Gram-positive bacteria belonging to the phylum Firmicutes and the order Lactobacillales. Cell division in this genus occurs along an axis in these bacteria, thus they grow in chains or pairs, hence the name—from Greek στρεπτός streptos, meaning easily bent or twisted. Most are oxidase-negative and catalase-negative, and many are facultative anaerobes, in 1984, many bacteria formerly considered Streptococcus were separated out into the genera Enterococcus and Lactococcus. Currently, over 50 species are recognised in this genus, however, many streptococcal species are not pathogenic, and form part of the commensal human microbiota of the mouth, skin, intestine, and upper respiratory tract. Furthermore, streptococci are an ingredient in producing Emmentaler cheese. Species of Streptococcus are classified based on their hemolytic properties, alpha-hemolytic species cause oxidization of iron in hemoglobin molecules within red blood cells, giving it a greenish color on blood agar. Beta-hemolytic species cause complete rupture of red blood cells, on blood agar, this appears as wide areas clear of blood cells surrounding bacterial colonies. Beta-hemolytic streptococci are further classified by Lancefield grouping, a serotype classification, the 20 described serotypes are named Lancefield groups A to V. In the medical setting, the most important groups are the alpha-hemolytic streptococci S. pneumoniae and Streptococcus viridans group, table, Medically relevant streptococci When alpha hemolysis is present, the agar under the colony is dark and greenish. Streptococcus pneumoniae and a group of oral streptococci display alpha hemolysis and this is sometimes called green hemolysis because of the color change in the agar. Other synonymous terms are incomplete hemolysis and partial hemolysis, alpha hemolysis is caused by hydrogen peroxide produced by the bacterium, oxidizing hemoglobin to green methemoglobin. S. pneumoniae, is a cause of bacterial pneumonia and occasional etiology of otitis media, sinusitis, meningitis. Inflammation is thought to be the cause of how pneumococci cause disease. The viridans streptococci are a group of commensal bacteria, that are either α-hemolytic, producing a green coloration on blood agar plates. Beta hemolysis, sometimes called complete hemolysis, is a complete lysis of red cells in the media around and under the colonies, streptolysin, an exotoxin, is the enzyme produced by the bacteria which causes the complete lysis of red blood cells. SLS affects immune cells, including polymorphonuclear leukocytes and lymphocytes, and is thought to prevent the host immune system from clearing infection, Streptococcus pyogenes, or group A Streptococcus, displays beta hemolysis. Some weakly beta-hemolytic species cause intense beta hemolysis when grown together with a strain of Staphylococcus and this is called the CAMP test. Clostridium perfringens can be identified presumptively with this test, Listeria monocytogenes is also positive on sheeps blood agar
8.
Gram-positive bacteria
–
Gram-positive bacteria are bacteria that give a positive result in the Gram stain test. Gram-positive bacteria take up the crystal violet stain used in the test and this is because the thick peptidoglycan layer in the bacterial cell wall retains the stain after it is washed away from the rest of the sample, in the decolorization stage of the test. Their peptidoglycan layer is thinner and sandwiched between an inner cell membrane and a bacterial outer membrane, causing them to take up the counterstain. Despite their thicker peptidoglycan layer, gram-positive bacteria are more receptive to antibiotics than gram-negative, peptidoglycan chains are cross-linked to form rigid cell walls by a bacterial enzyme DD-transpeptidase. A much smaller volume of periplasm than that in gram-negative bacteria, only some species have a capsule usually consisting of polysaccharides. Also only some species are flagellates, and when they do have flagella they only have two basal body rings to support them, both gram-positive and gram-negative bacteria commonly have a surface layer called an S-layer. In gram-positive bacteria, the S-layer is attached to the peptidoglycan layer, specific to gram-positive bacteria is the presence of teichoic acids in the cell wall. Some of these are lipoteichoic acids, which have a component in the cell membrane that can assist in anchoring the peptidoglycan. Along with cell shape, Gram staining is a method used to differentiate bacterial species. Historically, the kingdom Monera was divided into four divisions based primarily on Gram staining, based on molecular studies of the 16S sequences, Woese recognised twelve bacterial phyla. Two of these were both gram-positive and were divided on the proportion of the guanine and cytosine content in their DNA, the high G + C phylum was made up of the Actinobacteria and the low G + C phylum contained the Firmicutes. The Actinobacteria include the Corynebacterium, Mycobacterium, Nocardia and Streptomyces genera, the Firmicutes, have a 45–60% GC content, but this is lower than that of the Actinobacteria. The gram-positive and gram-negative staining response is not a reliable characteristic as these two kinds of bacteria do not form phylogenetic coherent groups. All gram-positive bacteria are bounded by a lipid membrane, and, in general. For the bacterial cells bounded by a cell membrane, the term monoderm bacteria or monoderm prokaryotes has been proposed. The presence of inner and outer cell membranes defines a new compartment in these cells and these bacteria have been designated as diderm bacteria. The distinction between the monoderm and diderm bacteria is supported by conserved signature indels in a number of important proteins, of these two structurally distinct groups of bacteria, monoderms are indicated to be ancestral. In general, gram-positive bacteria are monoderms and have a lipid bilayer whereas gram-negative bacteria are diderms and have two bilayers
9.
Community-acquired pneumonia
–
Community-acquired pneumonia refers to pneumonia contracted by a person with little contact with the healthcare system. The chief difference between hospital-acquired pneumonia and CAP is that patients with HAP live in long-term care facilities or have recently visited a hospital, CAP is common, affecting people of all ages, and its symptoms occur as a result of oxygen-absorbing areas of the lung filling with fluid. This inhibits lung function, causing dyspnea, fever, chest pains, CAP, the most common type of pneumonia, is a leading cause of illness and death worldwide. Its causes include bacteria, viruses, fungi and parasites, CAP is diagnosed by assessing symptoms, making a physical examination and on x-ray. Other tests, such as sputum examination, supplement chest x-rays, Patients with CAP sometimes require hospitalization, and it is treated primarily with antibiotics, antipyretics and cough medicine. Some forms of CAP can be prevented by vaccination and by abstaining from tobacco products, a definitive cause is identified in only half the cases. Infants can acquire lung infections before birth by breathing infected amniotic fluid or through an infection which crossed the placenta. Infants can also inhale contaminated fluid from the vagina at birth, the most prevalent pathogen causing CAP in newborns is Streptococcus agalactiae, also known as group-B streptococcus. GBS causes more than half of CAP in the first week after birth, other bacterial causes of neonatal CAP include Listeria monocytogenes and a variety of mycobacteria. CAP-causing viruses may also be transferred from mother to child, herpes simplex virus is life-threatening, maternally-derived syphilis is also a cause of CAP in this age group. CAP caused by fungi or parasites is not usually seen in otherwise-healthy infants, in contrast, older children and teenagers are more likely to acquire Mycoplasma pneumoniae and Chlamydophila pneumoniae than adults. A full spectrum of microorganisms is responsible for CAP in adults, identifying people at risk for infection by these organisms aids in appropriate treatment. Many less-common organisms can cause CAP in adults, and are identified from specific risk factors or treatment failure for common causes, some patients have an underlying problem which increases their risk of infection. Some risk factors are, Obstruction, When part of the leading to the alveoli is obstructed, the lung cannot eliminate fluid. One cause of obstruction, especially in children, is inhalation of a foreign object such as a marble or toy. The object lodges in an airway, and pneumonia develops in the obstructed area of the lung. Another cause of obstruction is lung cancer, which can block the flow of air, lung disease, Patients with underlying lung disease are more likely to develop pneumonia. Diseases such as emphysema and habits such as smoking result in more-frequent, in children, recurrent pneumonia may indicate cystic fibrosis or pulmonary sequestration
10.
George Miller Sternberg
–
Brigadier General George Miller Sternberg was a U. S. Army physician who is considered the first U. S. bacteriologist, having written Manual of Bacteriology. As the 18th U. S. Army Surgeon General, from 1893 to 1902, Sternberg led commissions to control typhoid and yellow fever, Sternberg also oversaw the establishment of the Army Medical School and of the U. S. Army Nurse Corps. The pioneering German bacteriologist Robert Koch honored Sternberg with the sobriquet, Sternberg was born at Hartwick Seminary, Otsego County, New York, where he spent most of his childhood. He was the eldest child of Levi Sternberg and Margaret Miller Stenberg and his father was a Lutheran clergyman, was descended from a German family from the Palatinate, which had settled in the Schoharie Valley in the early years of the 18th century. His father later became principal of Hartwick Seminary in Oneonta, New York and his mother, Margaret Levering Sternberg, was the daughter of George B. Miller, also a Lutheran clergyman and professor of theology at the seminary, as an eldest child of a large family and he was given adult responsibilities from an early age. He interrupted his studies at the seminary with a year of work in a bookstore in Cooperstown, during his last year at Hartwick he was an instructor in mathematics, chemistry, and natural philosophy. He was at the time pursuing the study of medicine with Horace Lathrop of Cooperstown. For his formal training he went first to Buffalo. After graduation he settled in Elizabeth, New Jersey to practice, remaining there until the outbreak of the Civil War. On May 28,1861, he was appointed an Assistant Surgeon in the U. S. Army and he managed to escape and soon joined his command in the defense of Washington. He later participated in the Peninsular campaign and saw service in the battles of Gaines Mill, during this campaign he contracted typhoid fever while at Harrisons Landing and was sent north on a transport. During the remainder of the war he performed hospital duty, mostly at Portsmouth Grove, Rhode Island, on March 13,1865, he was given the Brevets of captain and major for faithful and meritorious service. The years following the war followed the pattern of frequent moves typical of medical officers of the day. Louisa did not accompany him to the latter post, but joined him in 1867 just prior to an outbreak of cholera. She was one of the first civilians to develop the disease killed her within a few hours on July 15. Sternberg was promoted to captain on May 28,1866 and was sent to Fort Riley. With troops from this post he took part in expeditions against hostile Cheyenne Indians along the upper Arkansas River in Indian Territory
11.
Frederick Griffith
–
Frederick Griffith was a British bacteriologist whose focus was the epidemiology and pathology of bacterial pneumonia. He showed that Streptococcus pneumoniae, implicated in cases of lobar pneumonia. The observation was attributed to an unidentified transforming principle or transforming factor and this was later identified as DNA. Americas leading pneumococcal researcher, Oswald T. Avery, speculated that Griffith had failed to apply adequate controls and his discovery was one of the first to show the central role of DNA in heredity. Fred Griffith was born in Hale, Lancashire county, England, in late 1877, thereafter, he worked at the Liverpool Royal Infirmary, the Joseph Tie Laboratory, and the Royal Commission on Tuberculosis. In 1910 Fred Griffith was hired by the government board. Griffith performed the pivotal experiments—actually very many experiments—during the 1920s, with outbreak of World War II, the laboratory was expanded into the Emergency Public Health Laboratory Service. Pneumococci has two general forms—rough and smooth, injected subcutaneously with S form, mice succumbed to pneumonia and death within several days. However, the R form, lacking a capsule—its outer surface being cell wall—is relatively avirulent, when Griffith injected heat-killed S into mice, as expected, no disease ensued. When mice were injected with a mixture of heat-killed S and live R, however, pneumonia, the live R had transformed into S—and replicated as such—often characterized as Griffiths Experiment. Griffith also reported transformation of serological type—bacterial antigenicity—distinct from presence or absence of a capsule, types I, II, and III were each a distinct antigenic grouping, whereas type IV was a catchall of varying antigenicities not matching other types. Averys associate Martin Dawson at The Rockefeller Hospital confirmed each of Griffiths reported findings, even before Griffiths publication, Fred Neufeld had confirmed them as well, and was merely awaiting publication of Griffiths findings before publishing his confirmation. Microbiologists endeavored during the 1930s to dispel the monomorphist tenet, prevailing as institutional dogma, Scott amid an air raid during World War IIs London Blitz. A few weeks earlier, Scott had become director of the laboratory, both dated 3 May 1941, his obituary in The Lancet mentioned the historical discovery briefly, and his obituary in British Medical Journal failed to mention it. In 1944 identification of the factor was published in the Journal of Experimental Medicine by Avery, Colin MacLeod. Biologists made little more than speculation of Griffiths report of transformation until genetics research in 1951, Griffiths report was virtually ignored by clinicians, and by the medical sector as a whole. In 1931 Frederick Griffith coauthored a paper on acute tonsillitis—its sequelae, epidemiology, in 1934, Griffith reported voluminous findings on the serological typing of Streptococcus pyogenes. Streptococcal infection was a frequent coinfection complicating recovery from lobar pneumonia by pneumococci infection
12.
Bile
–
Bile or gall is a dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the digestion of lipids in the small intestine. In humans, bile is produced continuously by the liver, after eating, this stored bile is discharged into the duodenum. The composition of gallbladder bile is 97% water,0. 7% bile salts,0. 2% bilirubin,0. 51% fats, and 200 meq/l inorganic salts. Bile was the yellow bile in the four humor system of medicine, about 400 to 800 ml of bile is produced per day in adult humans. Bile acts to some extent as a surfactant, helping to emulsify the lipids in food, the hydrophilic sides are negatively charged, and this charge prevents fat droplets coated with bile from re-aggregating into larger fat particles. Ordinarily, the micelles in the duodenum have a diameter around 14–33 μm, a triglyceride is broken down into two fatty acids and a monoglyceride, which are absorbed by the villi on the intestine walls. After being transferred across the membrane, the fatty acids reform into triglycerides. Without bile salts, most of the lipids in food would be excreted in faeces, since bile increases the absorption of fats, it is an important part of the absorption of the fat-soluble substances, such as the vitamins A, D, E, and K. Besides its digestive function, bile serves also as the route of excretion for bilirubin, bilirubin derives from hemoglobin by glucuronidation. Bile tends to be alkali on average, the pH of common duct bile is higher than that of the corresponding gallbladder bile. It becomes more acidic in the gallbladder the longer you go without eating, as an alkali, it also has the function of neutralizing any excess stomach acid before it enters the duodenum, the first section of the small intestine. Bile salts also act as bactericides, destroying many of the microbes that may be present in the food, in the absence of bile, fats become indigestible and are instead excreted in feces, a condition called steatorrhea. Feces lack their characteristic color and instead are white or gray. Steatorrhea can lead to deficiencies in essential fatty acids and fat-soluble vitamins, in addition, past the small intestine the gastrointestinal tract and gut flora are not adapted to processing fats, leading to problems in the large intestine. The cholesterol contained in bile will occasionally accrete into lumps in the gallbladder, cholesterol gallstones are generally treated through surgical removal of the gallbladder. However, they can sometimes be dissolved by increasing the concentration of naturally occurring bile acids, such as chenodeoxycholic acid. On an empty stomach – after repeated vomiting, for example – a persons vomit may be green or dark yellow, the bitter and greenish component may be bile or normal digestive juices originating in the stomach. The color of bile is often likened to fresh-cut grass, unlike components in the stomach that look greenish yellow or dark yellow
