Persius/hicric huggingface dataset:
Kidney development

# Overview
In humans, the metanephros (adult kidney) begins as an aggregate of mesenchymal cells that are detectable by the fifth gestational week as two small areas in the intermediate mesoderm close to the pelvic aorta. It is approximately at this time that the nephric duct produces a finger-like projection called the ureteric bud that has, or will soon invade, the aggregate of cells known as the metanephric mesenchyme.
The ureteric bud of the nephric duct is stimulated by genetic signals emanating from the metanephric mesenchyme and the ureteric bud brings with it new genetic signals that will help the kidney form. The ureteric bud will grow into, and branch several times within, the metanephric mesenchyme, like a plant root penetrating and growing within ground soil.
Eventually, the ureteric bud will form the collecting ducts of the kidney and the ureters of the excretory system. The primitive nephric duct (pronephros) will degenerate to some degree but portions of it will go on to form the correct gender specific organs (gonads).
Once the ureteric bud has invaded the metanephric mesenchyme it will stimulate certain cells within the metanephric mesenchyme to condense around the tips of the branches of the ureteric bud and these cellular condensations will eventually form nephronic units (vascularized glomeruli).
In humans, all of the branches of the ureteric bud and the nephronic units have been formed by 32 to 36 weeks of gestation. However, these structures are not yet mature, and will continue to mature after birth. Once matured, humans have been estimated to possess approximately one million nephronic units (approximately 500,000 per kidney) or more.
After inducing the metanephric mesenchyme the lower portions of the nephric duct will migrate caudally (downward) and connect with the bladder, thereby forming the ureters. The ureters will carry urine from the kidneys to the bladder for excretion from the fetus into the amniotic sac. As the fetus develops, the torso elongates and the kidneys rotate and migrate upwards within the abdomen which causes the length of the ureters to increase.
Kimishige Ishizaka
Dr Template:Nihongo is a Japanese scientist who discovered the antibody class IgE in 1966. His work has been regarded as a major breakthrough in the understanding of allergy. He was awarded the 1973 Gairdner Foundation International Award and the 2000 Japan Prize for his work in immunology. He was elected a member of the United States National Academy of Sciences in 1983. Pupils include Tadamitsu Kishimoto, who worked with him at Johns Hopkins. He conducted much of his scientific work together with his wife, Teruka (Terry).

# Biography
Ishizaka obtained his medical qualifications and PhD from the University of Tokyo. From 1953 to 1962 he headed the immunoserology division at the department of serology at the Japanese National Institute of Health. During his position there he spent two years as a research fellow Caltech (1957-1959).
He settled permanently in the US in 1962, when he assumed the post of assistant professor of microbiology at the University of Colorado Medical School, as well as chief of immunology of its associated 
Children's Asthma Research Institute and Hospital Children's Asthma Research Institute and Hospital. He was promoted to associate professor in 1965. It was in Denver that he discovered IgE and its interplay with mast cells.
In 1970, Ishizaka was appointed as O'Neill Professor of Medicine and Microbiology at Johns Hopkins University School of Medicine in Baltimore, as well as Professor of Biology at the Faculty of Arts and Science. He worked there until 1989, when many of his junior researchers lost their research funding, and he became scientific director (and president from 1990) of the new La Jolla Institute for Allergy and Immunology in La Jolla, which was being set up with support from the Kirin Brewery Company.
He retired in 1996, and returned to Japan.

# Recognition
Ishizaka received numerous awards for his work in allergy and immunology. In 1972 he received the Passano Foundation Award, and in 1973 the German Paul-Ehrlich-und-Ludwig-Darmstaedter-Preis. 1973 saw him winning the prestigious Gairdner Foundation International Award, the Takeda Medical Award and the first Scientific Achievement Award of the International Association of Allergology. In 1974 he received the Asahi Cultural Award, the Emperor's Award by the Japan Academy, and the Japanese Order of Cultural Merit.
Knudson hypothesis

# Overview
The Knudson hypothesis is the hypothesis that cancer is the result of accumulated mutations to a cell's DNA. It was first proposed by Carl O. Nordling in 1953, and later formulated by Alfred G. Knudson in 1971. Knudson's work led indirectly to the identification of cancer-related genes. Knudson won the 1998 Albert Lasker Medical Research Award for this work.
The multi-mutation theory on cancer was proposed by Nordling in the British Journal of Cancer in 1953. He noted that in industrialized nations the frequency of cancer seems to increase according to the sixth power of age. This correlation could be explained by assuming that the outbreak of cancer requires the accumulations of six consecutive mutations.
Later, Knudson performed a statistical analysis on cases of retinoblastoma, a tumour of the retina which occurs both as an inherited disease and sporadically. He noted that inherited retinoblastoma occurs at a younger age than the sporadic disease. In addition, the children with inherited retinoblastoma often developed the tumour in both eyes, suggesting an underlying predisposition.
Knudson suggested that multiple "hits" to DNA were necessary to cause cancer. In the children with inherited retinoblastoma, the first insult was inherited in the DNA, and any second insult would rapidly lead to cancer. In non-inherited retinoblastoma, two "hits" had to take place before a tumour could develop, explaining the age difference.
It was later found that carcinogenesis (the development of malignancy) depended both on the activation of oncogenes (genes that stimulate cell proliferation) and deactivation of tumor suppressor genes (genes that keep proliferation in check). A first "hit" in an oncogene would not necessarily lead to cancer, as normally functioning tumor suppressor genes (TSGs) would still counterbalance this impetus; only damage to TSGs would lead to unchecked proliferation. Conversely, a damaged TSG (such as the Rb1 gene in retinoblastoma) would not lead to cancer unless there is a growth impetus from an activated oncogene.
Field cancerisation may be an extended form of the Knudson hypothesis. This is the phenomenon of various primary tumours developing in one particular area of the body, suggesting that an earlier "hit" predisposed the whole area for malignancy.
Koebner phenomenon

# Overview
The Koebner phenomenon, also called the "Koebner response" or the "isomorphic response", refers to skin lesions appearing on lines of trauma.  The Koebner phenomenon may result from either a linear exposure or irritation.

# Historical Perspective
The Koebner phenomenon was named after a rather eccentric, renowned German dermatologist, Heinrich Koebner (1838-1904).  Koebner is best known for his work in mycology.  Here is one story to illustrating his intense nature: in a medical meeting he proudly exhibited on his arms and chest three different fungus infections which he self-inoculated in order to prove the infectiousness of the organisms he was studying.  The Koebner phenomenon was the generalized term applied to his discovery that on psoriasis patients, new lesions often appear on lines of trauma which are often linear.

# Causes
Conditions demonstrating linear lesions after a linear exposure to a causative agent include:
- Molluscum contagiosum. Warts and molluscum contagiosum lesions can be spread in linear patterns by self-scratching ("auto-inoculation").
- Warts
- Rhus dermatitis (a dermatitis caused by poison ivy).  Rhus dermatitis lesions can appears linear either from brushing up against the plant or spreading of the urushiol by scratching.
In contrast to exposure causes of the Koebner phenomenon, the following disorders do not have an infective or chemical cause, instead, the irritation of trauma itself can act as a co-factor in producing linear patterns:
- Vitiligo
- Psoriasis
- Lichen planus
- Lichen nitidus
- Pityriasis rubra pilaris
- Keratosis follicularis (Darier disease)

# Differentiating Koebner Phenomenon From Other Diseases
The linear arrangement of skin lesions in the Koebner phenomenon can be contrasted to both lines of Blaschko and dermatomal distributions.   Blaschko lines follow embryonic cell migration patterns and are seen in some mosaic genetic disorders such as incontinentia pigmenti and pigment mosaicism.  Dermatomal distributions are lines on the skin surface following major nerves.  The rash caused by herpes zoster (Shingles) follows such dermatomal lines.
Lower motor neuron

# Overview
Lower motor neurons (LMNs) are the motor neurons connecting the brainstem and spinal cord to muscle fibers, bringing the nerve impulses from the upper motor neurons out to the muscles.

# Classification
Lower motor neurons are classified based on the type of muscle fiber they innervate:
- Alpha motor neurons (-MNs) innervate extrafusal muscle fibers, the most numerous type of muscle fiber and the one most involved in muscle contraction.
- Gamma motor neurons (-MNs) innervate intrafusal muscle fibers, which are involved with muscle spindles and the sense of body position.

# Physiology
Glutamate released from the upper motor neurons triggers depolarization in the lower motor neurons in the anterior horn which in turn causes an action potential to propagate the length of the axon to the neuromuscular junction where acetylcholine is released to carry the signal across the synaptic cleft to the postsynaptic receptors of the muscle cell membrane, signaling the muscle to contract.

# Consequences of lesions
Damage to lower motor neurons (lower motor neurone lesions) is indicated by abnormal EMG potentials, fasciculations, paralysis, weakening of muscles, and neurogenic atrophy of skeletal muscle.
Labor and Delivery

# Overview
Labor and Delivery, a labor ward or a labour ward is a department of a hospital devoted to childbirth.  In many hospitals, "Labor and Delivery" is one department and "Maternity", where a woman recovers following birth, is another.  In the United States, it is common practice to move a woman from Labor and Delivery to Maternity in the hour following birth.

# Benefits and drawbacks
Delivery in the birthing department of a hospital is common practice in Western culture.  Benefits include facilities and equipment for an emergency caesarean section and access to a neonatal intensive care unit (NICU).
Risks include drug complications (the leading adverse effect of hospitalization) and the possibility of a nosocomial infection (infection contracted in a hospital, the second most frequent adverse effect of hospitalization), responsible for 88,000 deaths in the United States in 1995.

# History
The first maternity ward in the United States is established at Bellevue Hospital Center in 1799.

# Alternatives
Alternatives to hospital delivery include birthing centers and home birth.
Lacrimal apparatus
The lacrimal apparatus is the physiologic system containing the orbital structures for tear production and drainage. It consists of:
- (a) the lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the eye;
- (b) the lacrimal canaliculi, the lacrimal sac, and the nasolacrimal duct, by which the fluid is conveyed into the cavity of the nose.
Lactococcus lactis
Synonyms and keywords: L. lactis

# Overview
Lactococcus lactis is a gram-positive bacteria used extensively in the production of buttermilk and cheese.  This group of bacteria, previously designated as lactic streptococci (Streptococcus lactis subsp. lactis or S. lactis subsp. cremoris) was placed in this new taxon in 1985 by Schleifer.

# Microbiology
Lactococcus lactis is a species of non-sporulating, non-motile, gram-positive bacteria.  They are cocci that group in pairs and short chains, typically 0.5 - 1.5 m in length.  When fermenting milk, L. lactis produce large quantities of lactic acid.  Cultured in the laboratory, L. lactis colonies appear bright orange on nutrient agar.

# Cheese production
L. lactis subsp. lactis (formerly Streptococcus lactis) is used in the early stages for the production of many cheeses including brie, camembert cheese, cheddar, colby, gruyere, parmesan, and roquefort.  The use of L. lactis in dairy factories is not without issues.  Bacteriophages specific to L. lactis cause significant economic losses each year by preventing the bacteria from fully metabolizing the milk substrate.  Several epidemiologic studies showed that the phages mainly responsible for these losses are from the species 936, c2 and P335.  L. lactis subsp. cremoris strains are preferred over L. lactis subsp. lactis strains because of their superior contribution to product flavor via unique metabolic mechanisms.  The DNA sequence divergence between the subspecies is estimated to be between 20 and 30%. Of the many lactococcal strains used, L. lactis subsp. cremoris SK11 is recognized for the beneficial flavor compounds it produces.
Lamellae (zoology)
A lamella is a thin plate-like structure, often one amongst many lamellae very close to one another, with open space between.  Aside from respiratory organs, they appear in other biological roles including filter feeding, the traction surfaces of geckos, and chloroplast membranes where high permeability is important.
In humans, the precursors of the prepuce during the development of the urinary and reproductive organs are called lamellae.
The microscopic lamellae in bone and nacre are lamellar structures in the materials science sense of the word.
In fish gills there are two types of lamellae, primary and secondary. The primary gill lamellae come out of the interbranchial septum to increase the contact area between the water and the blood capillaries. The secondary gill lamellae are small lamellae that come out of the primary ones and are used to further increase the contact area. Both types of lamellae are used to increase the amount of oxygen intake of the blood.
In birds, the water-feeding ducks and water birds have lamellae in their bills which are miniature ridges, like the 'teeth of a comb'. They act as a filter when feeding for organisms or plant matter.
simple:Lamella (zoology)
Straight leg raise
Synonyms and keywords: Lasegue's sign; lasegue test

# Overview
The straight leg raise is a test done during the physical examination to determine whether a patient with low back pain has an underlying herniated disk.

# Historical Perspective
It was named after Charles Lasegue (1816-1883).

# Technique
With the patient lying down on a table, the examiner lifts the patient's leg while the knee is straight.
A variation is to lift the leg while the patient is sitting. However, this reduces the sensitivity of the test.

# Interpretation
"The straight leg raise test is positive if pain in the sciatic distribution is reproduced between 30 and 70 passive flexion of the straight leg." 
A meta-analysis reported the accuracy as:
- Sensitivity 91%
- Specificity 26%
If raising the opposite leg causes pain (cross straight leg raising):
- Sensitivity 29%
- Specificity 88%
Lawesson's reagent
Lawesson's reagent, or LR, is a chemical compound used in organic synthesis as a thiation agent.  It is made by the reaction of anisole with phosphorus pentasulfide (P4S10).

# History
Lawesson's reagent was first made popular by Sven-Olov Lawesson, who did not, however, invent it. Lawesson's reagent was first made many years ago during a systematic study of the reactions of arenes with P4S10. In later years a series of inorganic chemists (Maingroup chemists) have explored the general chemistry of Lawesson's reagent and related compounds. Please see for details of the general chemistry of this class of compound the pages on naphthalen-1,8-diyl 1,3,2,4-dithiadiphosphetane 2,4-disulfide and the 1,3,2,4-dithiadiphosphetane 2,4-disulfides.

# Preparation
A mixture of anisole with phosphorus pentasulfide (P4S10) should be heated until the mixture is clear and no more hydrogen sulfide is formed. Recrystallization from toluene or xylene will yield pure LR.
As Lawesson's reagent has a strong and unpleasant smell, it is best to prepare the compound within a fume-hood and to treat all glassware used with a decontamination solution before taking the glassware outside the fume-hood. One common and effective method of destroying the  foul smelling residues is to use an excess of sodium hypochlorite (Chlorine bleach).

# Mechanism of action
Lawesson's reagent has a four membered ring of alternating sulfur and phosphorus atoms.  With heating, the central phosphorus/sulfur four-membered ring can open to form two reactive dithiophosphine ylides (R-PS2).  Much of the chemistry of lawessons's reagent is in fact the chemistry of these reactive intermediates. The existence of these reactive intermediates can be demonstrated simply by recording a 31P-{1H} NMR spectrum of a mixture of two different 1,3,2,4-dithiadiphosphetane 2,4-disulfides, the spectrum will have the two singlets for the original 1,3,2,4-dithiadiphosphetane 2,4-disulfides and two doublets for the 1,3,2,4-dithiadiphosphetane 2,4-disulfide formed by the combination of dithiophosphine ylides which bear different ancillary groups.

# Uses
The chemistry of Lawesson's reagent and related substances has been reviewed by several groups.  A common use of LR is to convert a carbonyl into a thiocarbonyl. For instance, an amide can be converted into a thioamide using Lawesson's reagent.  In addition LR has been used for the synthesis of thioesters and thioketones.
In general, the more electron rich a carbonyl is, the faster the carbonyl group will be converted into the corresponding thiocarbonyl by LR.
A combination of silver perchlorate and Lawesson's reagent is able to act as an oxophilic Lewis acid with the ability to catalyze the Diels-Alder reaction of dienes with ,-unsaturated aldehydes.
In one study  reaction of maltol with LR results in a selective oxygen replacement in two positions.
Lazarus phenomenon

# Overview
The Lazarus phenomenon is the  unexpected return of spontaneous circulation (ROSC) after resuscitation has been abandoned. The term is named after Lazarus, who according to the Bible was raised from the dead by Jesus.
Although no single cause has been identified, there have been several mechanisms of survival postulated for Lazarus phenomenon patients. Hyperkalaemia associated with renal failure can cause cardiac arrest, and in one such case survival has been documented, with appropriate treatment, after 26 minutes of asystole.
Also, in most cases in cardiac arrest the EEG becomes flat within about 10 seconds.

# Related Chapters
- Near-death experience
- Suspended animation
Left main bronchus

# Overview
The left main bronchus (or left primary bronchus, or left principal bronchus) is smaller in caliber but longer than the right, being nearly 5 cm long. It enters the root of the left lung opposite the sixth thoracic vertebra.
It passes beneath the aortic arch, crosses in front of the esophagus, the thoracic duct, and the descending aorta, and has the left pulmonary artery lying at first above, and then in front of it.
The left bronchus has no eparterial branch, and therefore it has been supposed by some that there is no upper lobe to the left lung, but that the so-called upper lobe corresponds to the middle lobe of the right lung.

# Additional images
- Anatomy of lungs.
- The tracheobronchial lymph glands.
- The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind.
Lifestyle diseases
Lifestyle diseases (also called diseases of longevity or diseases of civilization) are diseases that appear to increase in frequency as countries become more industrialized and people live longer. They include Alzheimer's disease, atherosclerosis, cancer, chronic liver disease or cirrhosis, Chronic Obstructive Pulmonary Disease, Type 2 diabetes, heart disease, nephritis or chronic renal failure, osteoporosis, acne, stroke, depression and obesity.

# Causes
Factors in diet, lifestyle, and the house are thought to influence susceptibility to the diseases listed below.  Smoking, alcohol and drug abuse as well as the lack of exercise may increase the risk of certain diseases in later life.

# International variation in cancer rates
A recent research paper published in the Lancet discussed the variation in cancer rates that evidences the existence of lifestyle diseases.
"In many Western countries, peoples' diet changed substantially in the second half of the twentieth century, generally with increases in consumption of meat, dairy products, vegetable oils, fruit juice, and alcoholic beverages, and decreases in consumption of starchy staple foods such as bread, potatoes, rice, and maize flour. Other aspects of lifestyle also changed, notably, large reductions in physical activity and large increases in the prevalence of obesity."
"It was noted in the 1970s that people in many Western countries had diets high in animal products, fat, and sugar, and high rates of cancers of the colorectum, breast, prostate, endometrium, and lung; by contrast, individuals in developing countries usually had diets that were based on one or two starchy staple foods, with low intakes of animal products, fat, and sugar, and low rates of these cancers."
"These observations suggest that the diets  of different populations might partly determine their rates of cancer, and the basis for this hypothesis was strengthened by results of studies showing that people who migrate from one country to another generally acquire the cancer rates of the new host country, suggesting that environmental  rather than genetic factors are the key determinants of the international variation in cancer rates."

# Death statistics in the United States
In 1900, the top three causes of death in the United States were pneumonia/influenza, tuberculosis, and diarrhea/enteritis. Communicable diseases accounted for about 60 percent of all deaths. In 1900, heart disease and cancer were ranked number four and eight respectively.  Since the 1940s, the majority of deaths in the United States have resulted from heart disease, cancer, and other degenerative diseases. And, by the late 1990s, degenerative diseases accounted for more than 60 percent of all deaths.
Ligamentum venosum
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The ligamentum venosum is the fibrous remnant of the ductus venosus of the fetal circulation. Usually, it is attached to the left branch of the portal vein within the porta hepatis of the liver. It may be continuous with the round ligament of liver (ligamentum teres).
It is invested by the peritoneal folds of the lesser omentum within a fissure on the inferior surface of the liver between the caudate and main parts of the left lobe.