Persius/hicric huggingface dataset:
Left ventricle

# Overview
The left ventricle is one of four chambers (two atria and two ventricles) in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.

# Shape
The left ventricle is longer and more conical in shape than the right, and on transverse section its concavity presents an oval or nearly circular outline. It forms a small part of the sternocostal surface and a considerable part of the diaphragmatic surface of the heart; it also forms the apex of the heart.

# Development
By teenage and adult ages, its walls have thickened to three to six times greater than that of the right ventricle. This reflects the typical five times greater pressure workload this chamber performs while accepting blood returning from the lungs veins at ~8mmHg pressure and pushing it forward to the typical ~120mmHg pressure in the aorta during each heartbeat. (The pressures stated are resting values and stated as relative to surrounding atmospheric which is the typical "0" reference pressure used in medicine.)

# Function
For excellence of health, the left ventricular muscle must:
- (a) relax very rapidly after each contraction so as to fill rapidly with oxygenated blood flowing from the lung veins, i.e. diastolic relaxation and filling.
- (b) contract rapidly and forcibly to force the majority of this blood into the aorta, overcoming the much higher aortic pressure and the extra pressure required to stretch the aorta and other major arteries enough to expand and make room for the sudden increase in blood volume, i.e. systolic contraction and ejection.
- (c) be able to rapidly increase or decrease its pumping capacity under nervous system control.

# Pumping volume
Typical healthy adult heart pumping volume is ~5 liters/min, resting. Maximum capacity pumping volume extends from ~25 liters/min for non-athletes to as high as ~45 liters/min for Olympic level athletes.

# Additional images
- Front view of heart and lungs.
- Base and diaphragmatic surface of heart.
Lactuca virosa
Lactuca virosa is a legal ethnobotanical in the United States. It is related to common lettuce (L. sativa), and is often called Wild Lettuce, Bitter lettuce, Laitue vireuse, Opium Lettuce, Poisonous Lettuce, or Rakutu-Karyumu-So.

# History
L. virosa was used in the 19th century by physicians when opium could not be obtained. It was studied extensively by the Council of the Pharmaceutical Society of Great Britain in 1911 . They discovered two chemicals responsible for the properties of L. virosa; lactucopicrin and lactucin.  In the United States, the plant experienced a resurgence in popularity in the 1970s. Today the plant is un-scheduled by the Food and Drug Administration (FDA), meaning it is legal to grow, purchase and own without prescription or license.

# Uses
The effects of ingesting L. virosa are similar to opium, although no opiates are present in the plant. Effects are felt quickly but do not last long, between half an hour to a couple of hours. They dwindle slowly. The plant has been used as an anesthetic and a sleep aid, as well as recreationally. Oils and extracts can be produced from L. virosa, they are often added to tea to help induce sleep. Many add the greens to salads, though the leaves of L. virosa are more bitter than other salad greens. Smoking involves either dried leaves or a sticky precipitate extracted from the leaves. Beverages can be prepared by soaking the leaves in alcohol.
The plant contains flavonoids, which have strong anti-oxidant properties. L. virosa has also been found to contain coumarins, and N-methyl--phenethylamine .  It has also been found to be a galactagogue for many women ( a substance which increases breast milk), particularly when used in combination with alfalfa.
Lacunar stroke
Synonyms and keywords: Lacunar infarction

# Introduction
Lacunar stroke occurs when one of the small arteries(:0.2 - 15mm) that provide blood to the brain's deep structures is blocked and injure deeper structures underneath the cortex.

# Pathophysiology
Lacunes are caused by occlusion of a single deep penetrating artery. The deep penetrating arteries are small nonbranching end arteries (usually smaller than 500 micrometers in diameter), which arise directly from much larger arteries (eg, the middle cerebral artery, anterior choroidal artery, anterior cerebral artery, posterior cerebral artery, posterior communicating artery, cerebellar arteries, basilar artery). Their small size and proximal position predisposes them to the development of microatheroma and lipohyalinosis.
At the beginning, lipohyalinosis was thought to be the main small vessel pathology of lacunes; however, microatheroma now is thought to be the most common mechanism of arterial occlusion (or stenosis). Occasionally, atheroma in the parent artery blocks the orifice of the penetrating artery (luminal atheroma), or atheroma involves the origin of the penetrating artery (junctional atheroma).
A hemodynamic (hypoperfusion) mechanism is suggested when there is a stenosis (and not occlusion) of the penetrating artery. When no evidence of small vessel disease is found on histologic examination, an embolic cause is assumed, either artery-to-artery embolism or cardioembolism. In one recent series, 25% of patients with clinical radiologically defined lacunes had a potential cardiac cause for their strokes.

# Diagnosis
It is estimated that lacunar infarcts account for 25% of all strokes that are due to infarction.
Patients tend to present with a pure motor, pure sensory or sensorimotor dysfunction or 'ataxic hemiparesis'. They will often recover well.
The imaging findings are
- An acute lacunar infarction (12 hours up to 7 days) appears as a small high-signal-intensity region on T2-weighted and FLAIR images and as a hypointense area on T1-weighted images.
High signal intensity is seen on diffusion-weighted images with corresponding low signal intensity on the apparent diffusion coefficient map.
Enhancement is variable
- High signal intensity is seen on diffusion-weighted images with corresponding low signal intensity on the apparent diffusion coefficient map.
- Enhancement is variable
- A chronic lacunar infarction is better defined and has high signal intensity on T2-weighted images and low signal intensity on T1-weighted images. On FLAIR images, a hyperintense lesion or a lesion with a hypointense center and a hyperintense rim reflecting gliosis is seen.
Enhancement may last for up to 8 weeks after the acute event
- Enhancement may last for up to 8 weeks after the acute event
Patient #1: Chronic lacunar infarctions on CT

# Related conditions
If there is enough white matter disease from lacunar pathology, one can see a subcortical dementia such as Binswanger disease.

# Related Chapters
stroke
Lamina propria

# Overview
The lamina propria is a constituent of the moist linings known as mucous membranes or mucosa, which line various tubes in the body (such as the respiratory tract, the gastrointestinal tract, and the urogenital tract).
The lamina propria (more correctly lamina propria mucosae) is a thin layer of loose connective tissue which lies beneath the epithelium and together with the epithelium constitutes the mucosa. As its Latin name indicates it is a characteristic component of the mucosa, "the mucosa's own special layer". Thus the term mucosa or mucous membrane always refers to the combination of the epithelium plus the lamina propria.
The lamina propria contains capillaries and a central lacteal (lymph vessel) in the small intestine, as well as lymphoid tissue. Lamina propria also contains glands with the ducts opening on to the mucosal epithelium, that secrete mucus and serous secretions.
Lateral sulcus

# Overview
The lateral sulcus (also called Sylvian fissure or lateral fissure) is one of the most prominent structures of the human brain.  It divides the frontal lobe and parietal lobe above from the temporal lobe below.  It is in both hemispheres of the brain but is longer in the left hemisphere. The lateral sulcus is one the earliest-developing sulci of the human brain. It first appears around the fourteenth gestational week.
The lateral sulcus has a number of side branches. Two of the most prominent and most regularly found are the ascending (also called vertical) ramus and the horizontal ramus of the lateral fissure, which subdivide the inferior frontal gyrus. The lateral sulcus also contains the transverse temporal gyri, which is part of the primary localized auditory cortex.
It was named the sylvian fissure after Franciscus Sylvius (1614-1672), professor of medicine at Leiden.
Laurasiatheria
Laurasiatheria is a clade of rank cohort or super-order, within the Placentalia (living) or Eutheria (Placentals and their extinct ancestors) infraclass of mammals, based on DNA sequence analyses and Retrotransposon presence/absence data. The name comes from the theory that these mammals evolved on the supercontinent of Laurasia, after it split from Gondwana when Pangaea broke up. It is a sister group to Euarchontoglires (Supraprimates) and Afrotheria. It includes the following extant orders:
- Erinaceomorpha: hedgehogs and gymnures
- Soricomorpha: moles, shrews, solenodons (cosmopolitan)
- Cetartiodactyla: cosmopolitan; includes former orders Cetacea (whales, dolphins and porpoises) and Artiodactyla (even-toed ungulates, including pigs, hippopotamus, camels, giraffe, deer, antelope, cattle, sheep, goats)
- Pegasoferae:
Pholidota: pangolins or scaly anteaters (Africa, South Asia)
Chiroptera: bats (cosmopolitan)
Carnivora: carnivores (cosmopolitan)
Perissodactyla: odd-toed ungulates
- Pholidota: pangolins or scaly anteaters (Africa, South Asia)
- Chiroptera: bats (cosmopolitan)
- Carnivora: carnivores (cosmopolitan)
- Perissodactyla: odd-toed ungulates
Within the Laurasiatheria, the Erinaceomorpha appears (surprisingly) to be the most divergent branch. Some studies link the Perissodactyla and Ferae in a clade Zooamata; others link Perissodactyla and Cetartiodactyla in a clade of true ungulates. Neither clade is well supported.
Laurasiatheria is also posited to include several extinct orders and superorders:
- Meridiungulata
- Condylarthra
- Dinocerata
- Mesonychia
- Cimolesta
- Creodonta
Lead(II) oxide
Lead(II) oxide is the chemical compound with the formula PbO. Lead(II) oxide occurs in two forms: red, having a tetragonal crystal structure and yellow, having an orthorhombic crystal structure. Both forms occur naturally as minerals: the red form is known as litharge and the yellow form is known as massicot.

# Preparation and structure
PbO is prepared by heating lead metal in air at 600 C.  Alternatively, it is obtained by the thermal decomposition of lead(II) nitrate or lead carbonate:
The structure of the solid, determined by X-ray crystallography, reveals a pyramidal four-coordinate Pb center.  The pyramidal nature indicates the presence of a stereochemically active lone pair of electrons.

# Reactions
The red and yellow forms of this material are related by a small change in enthalpy:
PbO(red)    PbO(yellow)  H = 1.6 kJ/mol
PbO is amphoteric, which means that it reacts with both acids and with bases.  With acids, it forms salts of Pb2+ via the intermediacy of oxo clusters such as 4+. With strong base, PbO dissolves to form plumbite(II) salts:
PbO  +  H2O  +  OH-    -

# Applications
PbO is a component of lead paints and is used extensively in manufacturing of lead glasses and ceramic glazes. PbO is the main ingredient of the paste used for filling the plates during manufacturing of lead-acid batteries. A mixture of PbO with glycerine sets to a hard, waterproof cement that has been used to join the flat glass sides and bottoms of aquaria, and was also once used to seal glass panels in window frames.
PbO is used in vulcanization of rubber.  PbO is used in certain condensation reactions in organic synthesis.
PbO is used in cathode ray tube glass to block X-ray emission, but mainly in the neck and funnel because it can cause discoloration when used in the faceplate.  Strontium oxide is preferred for the faceplate.
Lead time bias
Lead time bias is the length of time between when a disease becomes present in a person's body and its usual clinical presentation. It is an important factor when evaluating the effectiveness of a specific treatment.

# Relationship between screening and survival
By screening, the intention is to diagnose a disease earlier than it would be without screening. Without screening, the disease may be discovered later once symptoms appear.
Even if in both cases a person will die at the same time, because we diagnosed the disease early with screening, the survival time since diagnosis is longer with screening. No additional life has been gained (and indeed, there may be added anxiety as the patient must live with knowledge of the disease for longer).
Looking at raw statistics, screening will appear to increase survival time (this gain is called lead time). If we do not think about what survival time actually means in this context, we might attribute success to a screening test that does nothing but advance diagnosis.
Leishman stain
Leishman's stain, also Leishman stain, is used in microscopy for staining blood smears. It provides excellent stain quality. It is generally used to differentiate and identify leucocytes, malaria parasites, and trypanosomas. It is based on a mixture of methylene blue and eosin.
Leishman stain uses a methanol solution of staining dyes. 7-10 drops is applied to the slide with the specimen. After 20 seconds, 10-15 drops of a buffer solution (a Gurr buffer is used, pH 6.8) is added and mixed with the stain, then the specimen is left staying for 20-30 minutes, then washed off with the buffer solution.
Leishman stain is named after its inventor, the Scottish pathologist William Boog Leishman. It is similar to and partially replaceable with Giemsa stain, Jenner's stain, and identical to Wright's stain. Like them, it is a version of Romanowsky stain.
Trapezoid bone
The trapezoid bone (lesser multangular bone) is a carpal bone in tetrapods, including humans. It is the smallest bone in the distal row. It may be known by its wedge-shaped form, the broad end of the wedge constituting the dorsal, the narrow end the palmar surface; and by its having four articular facets touching each other, and separated by sharp edges.
The etymology derives from the Greek trapezion which means "irregular quadrilateral," from tra- "four" and peza "foot" or "edge." Literally, "a little table" from trapeza meaning "table" and -oeides "shaped."

# Surfaces
The superior surface, quadrilateral, smooth, and slightly concave, articulates with the scaphoid.
The inferior surface articulates with the proximal end of the second metacarpal bone; it is convex from side to side, concave from before backward and subdivided by an elevated ridge into two unequal facets.
The dorsal and palmar surfaces are rough for the attachment of ligaments, the former being the larger of the two.
The lateral surface, convex and smooth, articulates with the trapezium.
The medial surface is concave and smooth in front, for articulation with the capitate; rough behind, for the attachment of an interosseous ligament.
Levomethorphan
Levomethorphan is the l-stereoisomer of methorphan. The effects of the two isomers are quite different. Dextromethorphan is an antitussive on low doses and a dissociative on much higher doses, whereas levomethorphan is an opioid analgesic. Levomethorphan has effects similar to levorphanol but is less potent as it must be demethylated to the active form by liver enzymes before becoming active.

# Appearance in Fiction
In the Kay Scarpetta crime novel Body of Evidence, levomethorphan is used by 
a terminal cancer patient for relief of chronic pain. Eventually, she takes a fatal overdose (while Dr Scarpetta, coincidentally, is 
a guest in her house). Scarpetta, who is unfamiliar with this rarely-used 
drug, consults the decedent's doctors at the Johns Hopkins University oncology clinic 
and learns that it is regularly used for a few long-term, trusted patients.
sv:Levometorfan
Levosalbutamol

# Overview
Levosalbutamol (INN) or levalbuterol (USAN), trade name Xopenex, is the R-enantiomer of the short-acting 2-adrenergic receptor agonist albuterol (salbutamol).

# Uses
As a bronchodilator, it is used to treat asthma and COPD.  In general, levalbuterol has similar pharmacokinetic and pharmacodynamic properties to albuterol; however, its manufacturer, Sepracor, has implied (although not directly claimed) that the presence of only the R-enantiomer produces fewer side effects.
Physicians sometimes elect to use levalbuterol in patients with a history of supraventricular tachycardia or other arrhythmias because it is thought that levalbuterol may produce less direct effects on 1-adrenergic receptors in the heart.  For similar reasons, some pediatricians also use levalbuterol for patients who experience hyperactivity or jitteriness from racemic albuterol.

# Levosalbutamol vs. albuterol
The use of levalbuterol over the more traditionally used racemic albuterol is controversial among health care professionals.  That using levalbuterol instead of albuterol produces less direct effect on 1-adrenergic receptors and/or fewer cardiac side effects has been suggested, but not consistently demonstrated by long term, well-designed clinical trials.
There are differing opinions on whether there is sufficient therapeutic benefit to using levalbuterol that outweighs the 5-10 times higher price tag.  In general, it appears that if a clinician and patient feel that a low dose of racemic mixture is causing undesirable side effects, levalbuterol may be a viable alternative.

# Approval
Levalbuterol was originally available only as a solution for nebulizer and eventually become available as a CFC-free metered dose inhaler under the trade name "Xopenex HFA (levalbuterol tartrate) Inhalation Aerosol". The FDA approval date was on March 11, 2005. (See Official FAQ)
- A Xopenex HFA (levalbuterol tartrate) Inhalation Aerosol inhaler

# Additional studies
In a study conducted by Bill T. Ameredes, PhD, and colleagues from the University of Pittsburgh, that concluded that in combination corticosteroids treatments the (S)-isomer found in Albuterol had a profound nullifying effect. In the (R)- albuterol isomer it shown to enhance anti-inflammatory steroid treatment. 
In other works he considers the combination (R)(S)-Albuterol a problematic drug.
Repressor lexA
Repressor LexA or LexA is a repressor enzyme (EC 3.4.21.88) that represses SOS response genes  coding for DNA polymerases required for repairing DNA damage. LexA is intimately linked to RecA in the biochemical cycle of DNA damage and repair.  RecA binds to DNA-bound LexA causing LexA to cleave itself in a process called autoproteolysis.
DNA damage can be inflicted by the action of antibiotics. Bacteria require topoisomerases such as DNA gyrase or topoisomerase IV for DNA replication. Antibiotics such as ciprofloxacin are able to prevent the action of these molecules by attaching themselves to the gyrase - DNA complex. This is counteracted by the polymerase repair molecules from the SOS response. Unfortunately the action is partly counterproductive because ciprofloxacin is also involved in the synthetic pathway to RecA type molecules which means that the bacteria responds to an antibiotic by starting to produce more repair proteins.  These repair proteins can lead to eventual benevolent mutations which can render the bacteria resistant to ciproflaxin.
Mutations are traditionally thought of as happening as a random process and as a liability to the organism. Many strategies exist in a cell to curb the rate of mutations. Mutations on the other hand can also be part of a survival strategy. For the bacteria under attack from an antibiotic,  mutations help to develop the right biochemistry needed for defense. Certain polymerases in the SOS pathway are error-prone in their copying of DNA which leads to mutations.  While these mutations are often lethal to the cell, they can also lead to mutations which improve the bacteria's survival.  In the specific case of topoisomerases, some bacteria have mutated one of their amino acids so that the ciproflaxin can only create a weak bond to the topoisomerase. This is one of the methods that bacteria can becoming  resistant to antibiotics.
Impaired LexA proteolysis has been shown to interfere with ciprofloxacin resistance. This offers potential for combination therapy that combine quinolones with strategies aimed at interfering with the action of LexA either directly, or via RecA.
Splenic artery

# Overview
In anatomy, the splenic artery (in the past called the lienal artery) is the blood vessel that supplies oxygenated blood to the spleen.  It branches from the celiac artery, and follows a course superior to the pancreas.

# Branches
The splenic artery gives off branches to the stomach and pancreas before reaching the spleen.
Note that the branches of the splenic artery do not reach all the way to the lower part of the greater curvature of the stomach. Instead, that region is supplied by the right gastroepiploic artery, a branch of the gastroduodenal artery. The two gastroepiploic arteries anastomose with each other at that point.

# Vein
Along its course, it is accompanied by a similarly named vein, the splenic vein, which drains into the portal vein.

# Pathology
Splenic artery aneurysms are rare, but still the third most common abdominal aneurysm (after aneurysms of the abdominal aorta and iliac arteries).

# Additional images
- The celiac artery and its branches.
- Transverse section of the human spleen, showing the distribution of the splenic artery and its branches.
- Section of the spleen, showing the termination of the small bloodvessels.
- Posterior abdominal wall, after removal of the peritoneum, showing kidneys, suprarenal capsules, and great vessels.
Lifestyle drug
A lifestyle drug is a medication designed to improve the patient's quality of life by addressing relatively minor and non-life threatening conditions such as baldness, impotence, wrinkles, and obesity. Antidepressants are also sometimes called lifestyle drugs.
Pharmaceutical companies often reject the term "lifestyle drug" as perjorative; they claim that the term is subjectively applied and used to imply that the condition treated by the drug is unimportant. Nonetheless, the term is widely used in the media.
Critics argue that drug companies actively reclassify conditions once considered normal as "diseases" or "disorders" that can be treated medically with their products. "Halitosis" (bad breath), for example, was a concotion of Listerine's  marketing team, while "erectile dysfunction" was invented by Viagra's marketing team. Before the development and marketing of their respective treatments, neither bad breath nor impotence were considered disorders, but rather a normal part of life.
Social critics also question the propriety of devoting huge research budgets towards creating these drugs when far more dangerous diseases like cancer and AIDS remain uncured. It is sometimes claimed that lifestyle drugs amount to little more than medically sanctioned recreational drug use. Proponents, however, point out that improving the patient's subjective quality of life has always been a primary concern of medicine, and argue that these drugs are doing just that.
Many health insurance programs, such as those run by the government of Germany, do not cover payments for medications they classify as "lifestyle drugs".