415 resultados para DUCTS
Resumo:
The antidiuretic effect of vasopressin is mediated by V2 receptors (V2R) that are located in kidney connecting tubules and collecting ducts. This study provides evidence that V2R signaling is negatively regulated by regulator of G protein signaling 2 (RGS2), a member of the family of RGS proteins. This study demonstrates that (1) RGS2 expression in the kidney is restricted to the vasopressin-sensitive part of the nephron (thick ascending limb, connecting tubule, and collecting duct); (2) expression of RGS2 is rapidly upregulated by vasopressin; (3) the vasopressin-dependent accumulation of cAMP, the principal messenger of V2R signaling, is significantly higher in collecting ducts that are microdissected from the RGS2(-/-) mice compared with their wild-type littermates; and (4) analysis of urine output of mice that were exposed to water restriction followed by acute water loading revealed that RGS2(-/-) mice exhibit an increased renal responsiveness to vasopressin. It is proposed that RGS2 is involved in negative feedback regulation of V2R signaling.
Resumo:
Every year, a typical family in the United States spends around half of its home energy budget on heating and cooling. In Iowa, that percentage can be higher, due to temperature extremes reached during the winter and summer months. Unfortunately, many of those dollars often are wasted, because conditioned air escapes through leaky ceilings, walls and foundations—or flows through inadequately insulated attics, exterior walls and basements. In addition, many heating systems and air conditioners aren’t properly maintained or are more than 10 years old and very inefficient, compared to models being sold today. As a result, it makes sense to analyze your home as a collection of systems that must work together in order to achieve peak energy savings. For example, you won’t get anywhere near the savings you’re expecting from a new furnace if your airhandling ducts are uninsulated and leak at every joint. The most energy-efficient central air-conditioning setup won’t perform to your expectations if your attic insulation is inadequate and can’t reduce solar heat gain to help keep your home cool. And planting the wrong types of trees or shrubs close to your home adversely can affect potential energy savings all year long.
Resumo:
Renal excretion of water and major electrolytes exhibits a significant circadian rhythm. This functional periodicity is believed to result, at least in part, from circadian changes in secretion/reabsorption capacities of the distal nephron and collecting ducts. Here, we studied the molecular mechanisms underlying circadian rhythms in the distal nephron segments, i.e., distal convoluted tubule (DCT) and connecting tubule (CNT) and the cortical collecting duct (CCD). Temporal expression analysis performed on microdissected mouse DCT/CNT or CCD revealed a marked circadian rhythmicity in the expression of a large number of genes crucially involved in various homeostatic functions of the kidney. This analysis also revealed that both DCT/CNT and CCD possess an intrinsic circadian timing system characterized by robust oscillations in the expression of circadian core clock genes (clock, bma11, npas2, per, cry, nr1d1) and clock-controlled Par bZip transcriptional factors dbp, hlf, and tef. The clock knockout mice or mice devoid of dbp/hlf/tef (triple knockout) exhibit significant changes in renal expression of several key regulators of water or sodium balance (vasopressin V2 receptor, aquaporin-2, aquaporin-4, alphaENaC). Functionally, the loss of clock leads to a complex phenotype characterized by partial diabetes insipidus, dysregulation of sodium excretion rhythms, and a significant decrease in blood pressure. Collectively, this study uncovers a major role of molecular clock in renal function.
Resumo:
We here report the case history of a 75-yr-old woman who developed pancreatitis and recurrent symptomatic, cholestasis-induced hemobilia after percutaneous liver biopsy. An endoscopic sphincterotomy with clot extraction led to relief of symptoms. The risk of hemobilia after percutaneous liver biopsy is less than one per 1000 procedures, and only two cases of acute pancreatitis after percutaneous liver biopsy have previously been reported. To our knowledge, this is the first case in which endoscopic retrograde cholangiopancreatography was used to both diagnostic and therapeutic ends.
Resumo:
Sulku- jasäätölaitteita käytetään kaasuvirtausten estämiseen ja ohjaukseen. Yleinen rakennetyyppi on sälerakenne, jossa kanavaan asennettuja akseloituja säleitä kääntämällä saadaan virtauksen vapaata pinta-alaa säädettyä. Sulkulaitteiden virtauksenestokyky riippuu tiiveydestä kiinni-asennossa. Säätölaitteiden virtauksen rajoittamiskyky muuttuu asetuskulman mukaan eri konstruktioilla eri lailla. Työn tavoitteena on ollut tuottaa tehtyjen tutkimusten tuloksista pohjatiedot työn yhteydessä luotavaan raportointi- ja laskentasovellukseen, jolla on mahdollista riittävän tarkasti arvioida Sammet Dampers Oy:n tuotannossa olevien sälerakenteisten sulku- ja säälaitteiden ominaisuuksia ilman tapauskohtaista mittaamista tai mallintamista sekä tuottaa samalla asiakkaille valmiit raportit näistä ominaisuuksista. Tehtyjen tutkimusten pääpaino on ollut säätölaitteissa. Tutkimuksissa on selvitetty mm. säleiden lukumäärän, korkeussuhteen, sivusuhteen ja Reynoldsin luvun vaikutusta laitteen vastuskertoimeen ennalta määritellyillä asetuskulmilla. Tutkimukset koostuvat mallikokeista ja CFD-laskennasta. Lisäksi työn pohjana on ollut huomattava määrä aikaisempia selvityksiä. Työn tavoitteiden täyttämisessä on onnistuttu tyydyttävästi. Tutkittujen tekijöiden vaikutuksille vastuskertoimiin on luotu sovitteet mittausten ja CFD:n perusteella. CFDon osoittautunut käyttökelpoiseksi vain hyvin rajatulle joukolle tapauksia.
Resumo:
The case of a 41-year-old alcoholic patient who presented with massive upper gastrointestinal bleeding is reported. The diagnosis was established rapidly by endoscopy which revealed bleeding through the papilla of Vater. Selective angiography of the superior mesenteric artery opacified the pancreatic duct as well as the duodenum. CT scan showed signs of chronic pancreatitis. Because of the recurrence of bleeding and shock, an urgent operation was necessary and a Whipple procedure was performed. Recovery was complete. The clinical presentation, the etiology, the diagnostic modalities and the treatment of this particular condition are discussed. Usually, hemorrhage through the pancreatic duct presents as repeated episodes of upper gastrointestinal bleeding with no source found at endoscopy. The presence of chronic pancreatitis or of epigastric pain during bleeding should suggest the diagnosis. Upper gastrointestinal endoscopy and angiography are the principal diagnostic tools. Definitive treatment requires surgery, and resection in most of the cases.
Resumo:
Seventy-five percent of breast cancers are estrogen receptor α positive (ER(+)). Research on these tumors is hampered by lack of adequate in vivo models; cell line xenografts require non-physiological hormone supplements, and patient-derived xenografts (PDXs) are hard to establish. We show that the traditional grafting of ER(+) tumor cells into mammary fat pads induces TGFβ/SLUG signaling and basal differentiation when they require low SLUG levels to grow in vivo. Grafting into the milk ducts suppresses SLUG; ER(+) tumor cells develop, like their clinical counterparts, in the presence of physiological hormone levels. Intraductal ER(+) PDXs are retransplantable, predictive, and appear genomically stable. The model provides opportunities for translational research and the study of physiologically relevant hormone action in breast carcinogenesis.
Resumo:
There is increasing evidence to support a significant role for chronic non-bacterial, prostatic inflammation in the development of human voiding dysfunction and prostate cancer. Their increased prevalence with age suggests that the decrease of testosterone concentration and/or the ratio of testosterone-to-estradiol in serum may have a role in their development. The main objective of this study was to explore prostatic inflammation and its relationship with voiding dysfunction and prostate carcinogenesis by developing an experimental model. A novel selective estrogen receptor modulator (SERM), fispemifene, was tested for the prevention and treatment of prostatic inflammation in this model. Combined treatment of adult Noble rats with testosterone and estradiol for 3 to 6 weeks induced gradually developing prostatic inflammation in the dorsolateral prostatic lobes. Inflammatory cells, mainly T-lymphocytes, were first seen around capillaries. Thereafter, the lymphocytes migrated into the stroma and into periglandular space. When the treatment time was extended to 13 weeks, the number of inflamed acini increased. Urodynamical recordings indicated voiding dysfunction. When the animals had an above normal testosterone and estradiol concentrations but still had a decreased testosterone-to-estradiol ratio in serum, they developed obstructive voiding. Furthermore, they developed precancerous lesions and prostate cancers in the ducts of the dorsolateral prostatic lobes. Interestingly, inflammatory infiltrates were observed adjacent to precancerous lesions but not in the adjacency of adenocarcinomas suggesting that inflammation has a role in the early stages of prostate carcinogenesis. Fispemifene, a novel SERM tested in this experimental model, showed anti-inflammatory action by attenuating the number of inflamed acini in the dorsolateral prostate. Fispemifene exhibited also antiestrogenic properties by decreasing expression of estrogen-induced biomarkers in the acinar epithelium. These findings suggest that SERMs could be considered as a new therapeutic possibility in the prevention and in the treatment of chronic prostatic inflammation
Resumo:
Työn tavoitteena on talotekniikkaelementtitehtaan tuotekustannusmallin kehittäminen. Yritys tarvitsee tuotekohtaista kustannustietoa erityisesti varaston arvon määrittämiseen ja kustannusperusteiseen hinnoitteluun. Tuotekustannusmallin kehittäminen edellyttää nykyisen tuotekustannusmallin sisältämien virheiden ja puutteiden korjaamista. Työssä käydään läpi kaikki tuotekustannusmalliin tehdyt muutokset tuotantovaihekohtaisesti. Uusi tuotekustannusmalli perustuu lähinnä lisäys- ja standardikustannuslaskentaan. Malli laskee tuote- ja tilauskohtaisen minimiomakustannusarvon. Uusi tuotekustannusmalli kohdistaa tuotteille aiheuttamisperiaatteen mukaisesti monia sellaisia kustannuksia, jotka aikaisemmin on jätetty kokonaan kohdistamatta. Eristettyjen ilmanvaihtokanavien sekä vesi- ja lämpöjohtojen kustannusten havaittiin olevan aiemmin luultua matalammat. Elementtien runkojen kustannukset puolestaan nousivat uudessa mallissa. Työn aikana laadittiin myös taulukkolaskentasovellus, jonka avulla voidaan laskea tilaukseen sisältyvien elementtien hankintameno ja kustannusperusteinen hinta.
Resumo:
Coal, natural gas and petroleum-based liquid fuels are still the most widely used energy sources in modern society. The current scenario contrasts with the foreseen shortage of petroleum that was spread out in the beginning of the XXI century, when the concept of "energy security" emerged as an urgent agenda to ensure a good balance between energy supply and demand. Much beyond protecting refineries and oil ducts from terrorist attacks, these issues soon developed to a portfolio of measures related to process sustainability, involving at least three fundamental dimensions: (a) the need for technological breakthroughs to improve energy production worldwide; (b) the improvement of energy efficiency in all sectors of modern society; and (c) the increase of the social perception that education is a key-word towards a better use of our energy resources. Together with these technological, economic or social issues, "energy security" is also strongly influenced by environmental issues involving greenhouse gas emissions, loss of biodiversity in environmentally sensitive areas, pollution and poor solid waste management. For these and other reasons, the implementation of more sustainable practices in our currently available industrial facilities and the search for alternative energy sources that could partly replace the fossil fuels became a major priority throughout the world. Regarding fossil fuels, the main technological bottlenecks are related to the exploitation of less accessible petroleum resources such as those in the pre-salt layer, ranging from the proper characterization of these deep-water oil reservoirs, the development of lighter and more efficient equipment for both exploration and exploitation, the optimization of the drilling techniques, the achievement of further improvements in production yields and the establishment of specialized training programs for the technical staff. The production of natural gas from shale is also emerging in several countries but its production in large scale has several problems ranging from the unavoidable environmental impact of shale mining as well as to the bad consequences of its large scale exploitation in the past. The large scale use of coal has similar environmental problems, which are aggravated by difficulties in its proper characterization. Also, the mitigation of harmful gases and particulate matter that are released as a result of combustion is still depending on the development of new gas cleaning technologies including more efficient catalysts to improve its emission profile. On the other hand, biofuels are still struggling to fulfill their role in reducing our high dependence on fossil fuels. Fatty acid alkyl esters (biodiesel) from vegetable oils and ethanol from cane sucrose and corn starch are mature technologies whose market share is partially limited by the availability of their raw materials. For this reason, there has been a great effort to develop "second-generation" technologies to produce methanol, ethanol, butanol, biodiesel, biogas (methane), bio-oils, syngas and synthetic fuels from lower grade renewable feedstocks such as lignocellulosic materials whose consumption would not interfere with the rather sensitive issues of food security. Advanced fermentation processes are envisaged as "third generation" technologies and these are primarily linked to the use of algae feedstocks as well as other organisms that could produce biofuels or simply provide microbial biomass for the processes listed above. Due to the complexity and cost of their production chain, "third generation" technologies usually aim at high value added biofuels such as biojet fuel, biohydrogen and hydrocarbons with a fuel performance similar to diesel or gasoline, situations in which the use of genetically modified organisms is usually required. In general, the main challenges in this field could be summarized as follows: (a) the need for prospecting alternative sources of biomass that are not linked to the food chain; (b) the intensive use of green chemistry principles in our current industrial activities; (c) the development of mature technologies for the production of second and third generation biofuels; (d) the development of safe bioprocesses that are based on environmentally benign microorganisms; (e) the scale-up of potential technologies to a suitable demonstration scale; and (f) the full understanding of the technological and environmental implications of the food vs. fuel debate. On the basis of these, the main objective of this article is to stimulate the discussion and help the decision making regarding "energy security" issues and their challenges for modern society, in such a way to encourage the participation of the Brazilian Chemistry community in the design of a road map for a safer, sustainable and prosper future for our nation.
Resumo:
Työssä tutkitaan kattilalaitosten vaativien, ulkoista kuormaa kantavien savukaasu- ja palamisilmakanavien rakennemitoitusta. Teoriaosuudessa esitetään vaativien kanavien mitoituksessa tarvittava levy- ja palkkilujuusoppi. Kantavien rakenteiden Eurokoodi-standardien soveltuvuutta kanavien mitoitukseen on tutkittu elementtimenetelmän avulla. Tutkittuja menetelmiä sovelletaan case-rakenteen mitoituksessa.
Resumo:
Direct-driven permanent magnet synchronous generator is one of the most promising topologies for megawatt-range wind power applications. The rotational speed of the direct-driven generator is very low compared with the traditional electrical machines. The low rotational speed requires high torque to produce megawatt-range power. The special features of the direct-driven generators caused by the low speed and high torque are discussed in this doctoral thesis. Low speed and high torque set high demands on the torque quality. The cogging torque and the load torque ripple must be as low as possible to prevent mechanical failures. In this doctoral thesis, various methods to improve the torque quality are compared with each other. The rotor surface shaping, magnet skew, magnet shaping, and the asymmetrical placement of magnets and stator slots are studied not only by means of torque quality, but also the effects on the electromagnetic performance and manufacturability of the machine are discussed. The heat transfer of the direct-driven generator must be designed to handle the copper losses of the stator winding carrying high current density and to keep the temperature of the magnets low enough. The cooling system of the direct-driven generator applying the doubly radial air cooling with numerous radial cooling ducts was modeled with a lumped-parameter-based thermal network. The performance of the cooling system was discussed during the steady and transient states. The effect of the number and width of radial cooling ducts was explored. The large number of radial cooling ducts drastically increases the impact of the stack end area effects, because the stator stack consists of numerous substacks. The effects of the radial cooling ducts on the effective axial length of the machine were studied by analyzing the crosssection of the machine in the axial direction. The method to compensate the magnet end area leakage was considered. The effect of the cooling ducts and the stack end area effects on the no-load voltages and inductances of the machine were explored by using numerical analysis tools based on the three-dimensional finite element method. The electrical efficiency of the permanent magnet machine with different control methods was estimated analytically over the whole speed and torque range. The electrical efficiencies achieved with the most common control methods were compared with each other. The stator voltage increase caused by the armature reaction was analyzed. The effect of inductance saturation as a function of load current was implemented to the analytical efficiency calculation.
Resumo:
We show an anatomical modification of extrahepatic biliary ducts in a fifty-eight years old female who presented right hipocondric pain, jaundice and fever two months after cholecystectomy. The patient underwent ERCP wich showed an anatomical modification that consists in an union of the right and left hepatic ducts, with insertion into the cystic duct, right hepatic duct, being a choledochus agenesis.
Resumo:
The authors present a case of distal common bile duct injury. Ligation of the bile duct and a bypass cholecystojejunostomy were chosen as treatment. Diagnosis of blunt traumatic injury to the extrahepatic biliary ducts may be difficult due to the benign nature of initial bile peritonitis. Surgical treatment for associated abdominal injuries usually makes the diagnosis possible. One of the challenges in the treatment of these injuries relates to the small diameter of the, usually, normal common bile duct. Primary repair and T tube drainage is the best option for non-complex injuries. End-to-end anastomosis and, preferentially, biliary-enteric anastomosis are the best surgical options for more complex injuries. Severe injuries have high complication rates, especially when the distal portion of the common bile duct is affected. Early leaks and late strictures are likely to develop in these situations. Cholecistojejunostomy and ligation of the injuried common bile duct are good surgical options for complex injuries. They carry a low complication rate and consequently low morbidity.
Resumo:
The authors report a case of spontaneous perforation of the biliary tract (S.P.B.T) in a three-month-old infant. The diagnosis was suspected before the operation by clinical signs and diagnostic tests. The importance of paracentesis and scintigraphy is stressed. A surgical approach was chosen and drainage procedure of the area around the perforation and a cholecystostomy were done. S.P.B.T. is rare and its etiology is controversial, but cannot be forgotten in association between biliary ascites and cholestatic jaundice during the first months of life.