SUMMARY / RELATED TOPICS

Necrosis

Necrosis is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma which result in the unregulated digestion of cell components. In contrast, apoptosis is a occurring programmed and targeted cause of cellular death. While apoptosis provides beneficial effects to the organism, necrosis is always detrimental and can be fatal. Cellular death due to necrosis does not follow the apoptotic signal transduction pathway, but rather various receptors are activated and result in the loss of cell membrane integrity and an uncontrolled release of products of cell death into the extracellular space; this initiates in the surrounding tissue an inflammatory response, which attracts leukocytes and nearby phagocytes which eliminate the dead cells by phagocytosis. However, microbial damaging substances released by leukocytes would create collateral damage to surrounding tissues.

This excess collateral damage inhibits the healing process. Thus, untreated necrosis results in a build-up of decomposing dead tissue and cell debris at or near the site of the cell death. A classic example is gangrene. For this reason, it is necessary to remove necrotic tissue surgically, a procedure known as debridement. Structural signs that indicate irreversible cell injury and the progression of necrosis include dense clumping and progressive disruption of genetic material, disruption to membranes of cells and organelles. There are six distinctive morphological patterns of necrosis: Coagulative necrosis is characterized by the formation of a gelatinous substance in dead tissues in which the architecture of the tissue is maintained, can be observed by light microscopy. Coagulation occurs as a result of protein denaturation, causing albumin to transform into a firm and opaque state; this pattern of necrosis is seen in hypoxic environments, such as infarction. Coagulative necrosis occurs in tissues such as the kidney and adrenal glands.

Severe ischemia most causes necrosis of this form. Liquefactive necrosis, in contrast to coagulative necrosis, is characterized by the digestion of dead cells to form a viscous liquid mass; this is typical of bacterial, or sometimes fungal, infections because of their ability to stimulate an inflammatory response. The necrotic liquid mass is creamy yellow due to the presence of dead leukocytes and is known as pus. Hypoxic infarcts in the brain presents as this type of necrosis, because the brain contains little connective tissue but high amounts of digestive enzymes and lipids, cells therefore can be digested by their own enzymes. Gangrenous necrosis can be considered a type of coagulative necrosis that resembles mummified tissue, it is characteristic of ischemia of the gastrointestinal tracts. If superimposed infection of dead tissues occurs liquefactive necrosis ensues Caseous necrosis can be considered a combination of coagulative and liquefactive necrosis caused by mycobacteria and some foreign substances.

The necrotic tissue appears as friable, like clumped cheese. Dead cells disintegrate but are not digested, leaving granular particles. Microscopic examination shows amorphous granular debris enclosed within a distinctive inflammatory border. Granuloma has this characteristic. Fat necrosis is specialized necrosis of fat tissue, resulting from the action of activated lipases on fatty tissues such as the pancreas. In the pancreas it leads to acute pancreatitis, a condition where the pancreatic enzymes leak out into the peritoneal cavity, liquefy the membrane by splitting the triglyceride esters into fatty acids through fat saponification. Calcium, magnesium or sodium may bind to these lesions to produce a chalky-white substance; the calcium deposits are microscopically distinctive and may be large enough to be visible on radiographic examinations. To the naked eye, calcium deposits appear as gritty white flecks. Fibrinoid necrosis is a special form of necrosis caused by immune-mediated vascular damage.

It is marked by complexes of antigen and antibodies, sometimes referred to as "immune complexes" deposited within arterial walls together with fibrin. There are very specific forms of necrosis such as gangrene, gummatous necrosis and hemorrhagic necrosis; some spider bites may lead to necrosis. In the United States, only spider bites from the brown recluse spider reliably progress to necrosis. In other countries, spiders of the same genus, such as the Chilean recluse in South America, are known to cause necrosis. Claims that yellow sac spiders and hobo spiders possess necrotic venom have not been substantiated. In blind mole rats, the process of necrosis replaces the role of the systematic apoptosis used in many organisms. Low oxygen conditions, such as those common in blind mole rats' burrows cause cells to undergo apoptosis. In adaptation to higher tendency of cell death, blind mole rats evolved a mutation in the tumor suppressor protein p53 to prevent cells from undergoing apoptosis. Human cancer patients have similar mutations, blind mole rats were thought to be more susceptible to cancer because their cells cannot undergo apoptosis.

However, after a specific amount of time, the cells in blind mole rats

1982 Austrian Grand Prix

The 1982 Austrian Grand Prix was a Formula One motor race held on 15 August 1982 at the Österreichring in Spielberg, Austria. The race, contested over 53 laps, was the thirteenth race of the 1982 Formula One season and was won by Elio de Angelis, driving a Lotus-Ford. De Angelis held off Keke Rosberg's Williams-Ford to win by just 0.05 seconds, or less than half a car length. Jacques Laffite finished third in a Ligier-Matra, one lap behind. A chicane had been added at the entrance to the pits earlier in the year. Nelson Piquet's Brabham led into the first corner from pole position, while Renault's Alain Prost passed Piquet's team-mate Riccardo Patrese for second. Further back, there was a collision which eliminated the two Alfa Romeos of Andrea de Cesaris and Bruno Giacomelli, as well as the Williams of Derek Daly. Prost's advantage over Patrese lasted only a few corners before the Italian re-passed him. On lap 2, Patrese took the lead from Piquet and the two Brabhams began to pull away on their half-full tanks.

Shortly before half distance, Piquet made the first planned mid-race fuel and tyre pit stop in modern F1 history. He rejoined in fourth place, behind Prost and Elio de Angelis, just ahead of Keke Rosberg. Shortly afterwards, Patrese made his stop, having built up a sufficient lead to rejoin the race still in first place. However, the Italian suffered an engine failure three laps leaving Prost to inherit a comfortable lead from de Angelis. Piquet was back up to third but was now in trouble, unable to make any inroads into the leaders and struggling to stay ahead of Rosberg. On lap 32, the Brazilian retired with an electrical failure. Free of the Brabham, Rosberg began closing in on de Angelis, who at this point was ten seconds ahead. Prost was leading by half a minute when on lap 49, five from the end, his Renault suffered a mechanical failure; this left de Angelis and Rosberg – neither of whom had won a Grand Prix before – battling for the lead. At the start of the last lap de Angelis was 1.6 seconds ahead.

Rosberg closed on the final tour and was right on the Lotus's gearbox heading into the final corner, the Rindt Kurve. De Angelis calmly slid wide on the exit of the corner. Rosberg dived inside on the home straight, only to come up short by 0.050 seconds, or less than half a car length. De Angelis joyfully celebrated his maiden win, while Rosberg had nonetheless boosted his Driver's Championship chances, moving into second place ahead of John Watson, who had suffered an engine failure. Ligier's Jacques Laffite completed the podium, coming home a lap down, while Patrick Tambay was fourth in the sole Ferrari, having recovered from a puncture early in the race. Watson's McLaren team-mate Niki Lauda was fifth, with Mauro Baldi taking the final point in his Arrows; this was the 150th World Championship race victory for the Cosworth DFV engine. However, it was to be the last hailed by Colin Chapman's famous act of throwing his cloth cap into the air after a Lotus victory, as Chapman would die four months later.

It was the last win by a Chapman-built Lotus, the team's last win until the 1985 Portuguese Grand Prix. Nelson Piquet 1, Riccardo Patrese 26, Alain Prost 21, Elio de Angelis 5. Note: Only the top five positions are included for both sets of standings

Santiago Municipal Airport

Santiago Municipal Airport was a both passenger and military airport located in the Center of Santiago de los Caballeros, Dominican Republic. This airport served this city with daily flights to San Juan in Puerto Rico, Port-au-Prince in Haiti, Santiago de Cuba and others, it was the major Hub of Dominair. It was used as a secondary hub by the FAD; this Airport was built in the 1930s, during Trujillo's government, with the major propose to stimulate the city's growth. The operations were focused to the passenger movements between San Juan and Santiago, the cargo operations to San Juan, Santo Domingo and Port-au-Prince. Before ceasing operations, Dominicana de Aviación became the first airline to connect Santiago with the United States, starting operations between Santiago and Miami, in McDonnell Douglas DC-6 Aircraft in the 1970s. In the 1990s, another Dominican airline, started operations in the airport, with two daily flights to San Juan, they added flights to Port-au-Prince three years later.

In 1998 the airport had the biggest expansion ever. They enlarged the runway to support operation of the American Eagle's ATR aircraft; the airport reminded closed for at least eight months. In 1999 American Eagle started, for the first time, operations in Santiago, adding two daily flights to San Juan, making Dominair to leave the route. In 2002 the airport closed its doors to the public due to the inauguration of a bigger airport, Cibao International Airport, located 15 minutes away from the city center; this new airport allowed jet-passenger aircraft operations and could receive flights from New York and San Juan, which Santiago Municipal Airport could not handle. On March 18, 2002, the two American Eagle's flights to San Juan were transferred to the new Cibao International Airport, ceasing passenger operations in Santiago Municipal Airport. A Year the Santiago Air Base became unnecessary for the FAD, a cost that they could not handle by themselves, so they moved all operations to the Puerto Plata Air Base.

Santiago Municipal was now closed, with no operations at all. Santiago Municipal Airport is now known as Cibao Center National Police, north command of operations for the National Police. American Airlines American Eagle Dominicana de Aviación Dominair Santiago Municipal Airport was the secondary hub for the Dominican Air Force, they had at least 30% of their operations in this airport. They had their own ramp and terminal, located behind the hangars of the Civil Aviation, next to the control tower. All the military operations to the northwest of the country were originated from Santiago Municipal, which people referred to as Santiago Air Base, pointing the Military Terminal; the Central Park of Santiago is projected to be constructed on the land of the now defunct old Santiago Municipal Airport that now lodges the regional seat of the National Police and the offices of the Association for Development. The industrialists of Santiago have defended the project since it is considered to be a solution to the lack of green spaces suitable for relaxation in the city.

It has been argued that the granting of contracts for the different phases from this project violate the frame of transparency and legality. In the Strategic Plan of Santiago it is indicated that the construction of the Metropolitan Park would increase the Santiagos green area from its 1.1% to 4% While the old military side of the airport is now used for the National Police, the old passenger terminal side is now used as a racetrack. FAD3069 Bell 205 Bell 205 FAD3069 Santiago Municipal Airport