887 resultados para Col·lapse gravitacional
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This paper aims to describe the uterine and ovarian ultrasonographic characteristics and Doppler velocimetric features of their arteries in bitches during the periovulatory period. Fifteen estrous cycles in 10 animals were evaluated. The ultrasonographic characteristics, resistance indices (RI) and pulsatility indices (PI) of the uterus and ovaries in each animal were recorded 5 days before and after ovulation (D0). The data were statistically analyzed, and the results were expressed as the mean ± standard error of mean (P<0.05). In results the ultrasonographic features of the uterus were the same on all of the cycles and evaluated days. The uterus had an average diameter of 0.85±0.02cm. An increase in the volume of the ovaries and the diameter of the ovarian follicles were measured. Ovaries had a volume of 0.64±0.06cm³, and the follicles cavities had a diameter of 0.46 ± 0.01 cm on the day of ovulation. After ovulation, it was observed that some follicles not collapse in some cycles. Two days prior to ovulation, the uterine blood perfusion decreased. This decrease remained unchanged until ovulation. Following ovulation, we measured a gradual increase in the uterine perfusion and in the ovarian artery. This artery directed blood flow to the ovaries and increased the intra-ovarian perfusion on the day after ovulation. In conclusion, specific features are observed in the uterus and ovarian ultrasound image and Doppler values of their arteries presented on the periovulatory days and when associated allow to estimate more accurately the date of ovulation.
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Metsäteollisuus on tullut Suomeen ulkomaisen pääoman ja tietotaidon avulla vajaat kaksisataa vuotta sitten. Se on toiminut melkein koko jatkosodan jälkeisen ajan suojatussa ympäristössä ja ulkomaisesta kilpailusta riippumattomassa toimintaympäristössä. Kuten Porter ja muut ovat todistaneet, tällainen toimintaympäristö ei kehitä kansainvälisesti kilpailukykyistä teollisuutta globaaleilla markkinoilla. Liittyminen Euroopan unioniin ja sittemmin Euroopan rahaliittoon saattoi puunjalostusteollisuuden täysin uudenlaiseen kilpailutilanteeseen. Sama tapahtui myös alan pk-yrityksille, jotka olivat joutuneet toimimaan heikosti kilpailluilla raaka-ainemarkkinoilla. Tutkimus on tulevaisuudentutkimus, jossa tutkimusongelmia lähestytään kolmen teorian avulla. Porterin klusteriteoria tarjoaa mahdollisuuden arvioida metsäteollisuutta sekä kokonaisuutena että toimivana monimuotoisena organisaationa, jossa kustannukset ja hinta muodostuvat arvoketjun toimijoiden osakustannuksista. Bionomiateoria eli darvinistinen talousteoria testaa suomalaisen puunjalostusteollisuuden pk-yritysten kilpailukykyä ja paineita hakeutua edullisemmille toiminta- alueille. Evoluutioteoria tarkastelee sukupolvenvaihdoksen problematiikkaa. Sukupolvenvaihdoksen onnistuminen muodostuu puutoimialan elämän ja kuoleman kysymykseksi. Tämä on etenkin pk-yrityksiä kohtaava ongelma. Asiaa selvitettiin Mauno Rintalan suorittamalla kyselytutkimuksella Puuteollisuusyrittäjien jäsenistön keskuudessa. Ongelma johtuu suurista sodan jälkeen syntyneistä ikäluokista. Nämä vuosina 1945– 50 syntyneet ovat siirtymässä eläkkeelle vuosien 2005 ja 2015 välillä. Kyseisissä ikäluokissa yritystiheys on noin kaksi kertaa suurempi kuin sen jälkeisissä ikäluokissa. Suoritetun kyselyn sekä muiden suomalaisten ja kansainvälisten tutkimusten perusteella näyttää siltä, että eläkkeelle siirryttäessä vain noin 30 %:lla yrityksistä on jatkaja tiedossa suvusta tai lähipiiristä. Tämä merkitsee sitä, että 70 % eläköityvän ikäluokan omistamista yrityksistä poistuu pysyvästi markkinoilta. Suomessa poistuma merkitsee noin 40 % koko yritysvarannosta eli noin 80 000 yritystä. Tilastot toimivien yritysten määrästä ovat kuitenkin hyvin ristiriitaisia, joten todellista määrää on mahdoton arvioida. Noin suuren määrän poistuminen markkinoilta uhkaa jo hyvinvointivaltion perusrakenteita. Tutkimustulos edellyttää nopeita toimenpiteitä teollisten pkyritysten pelastamiseksi ja säilyttämiseksi Suomessa. Sukupolvenvaihdoksen onnistuminen on tässä prosessissa ensiarvoisessa asemassa. Kaikkien edellä mainittujen yritysten poistuminen markkinoilta edellyttäisi noin 400 000 uuden yrityksen perustamista, koska ainoastaan noin 20 % yrityksistä selviää ensimmäiset kolme vuotta. Tutkimukseen perustuen esitetään prosessimalli sukupolvenvaihdoksen suorittamiseksi. Suomen tärkeimmissä kilpailijamaissa valtioiden metsäomistus on määräävässä asemassa. Meillä metsät ovat yksityisessä omistuksessa ja vain pieni osa valtion omistuksessa. Puumarkkinat toimivat markkinatalouden ehdoilla ilman valtion ohjausta. Ongelmaksi on kehittymässä puun saanti. Metsänomistus on sukupolvien myötä hajaantunut hyvin pieniksi metsälöiksi. Nykyiset metsänomistajat asuvat kaupungeissa ja ovat pääosin palkkatyössä. He eivät ole samalla tavoin riippuvaisia puutuloista kuin heidän esi-isänsä. Metsäverotuksen uudistuminen lisää puun saannin epävarmuutta. Se on muuttumassa pinta-alaverotuksesta puun myynnin verotukseen. Puun myynti on vilkasta ennen järjestelmien vaihtumista ja vähäisempää sen jälkeen. Myös näitä ongelmia on pyritty ratkomaan uudenlaisen metsänomistusmallin avulla. Puuteollisuus on hyvin vanha teollisuudenala. Raaka-aine muodostaa määräävän osan kustannuksista. Muutokset ovat hitaita ja todelliset innovaatiot pitkäkestoisia. Uusia innovaatioita tapahtuu harvoin. Kannattavuutta parannetaan tuoteprosessien ja arvoketjujen kehittämisen kautta. Yhteiskunnan osuus alan kehittämisessä ja säilyttämisessä on ratkaiseva. Asioiden moninaisuus tekee tutkimuksen vaikeaksi, mutta sitäkin tärkeämmäksi kansantalouden kannalta. Tällaisissa suurissa murroksissa korostuu kaikkien päättävien tahojen henkinen valmius ja tahto tehdä oikeita ratkaisuja oikeaan aikaan.
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Ever since Siad Barre’s regime was toppled in the beginning of the 1990’s Somalia has been without an effective central government. As a result Somalia has remained in an anarchic condition of state collapse for nearly two decades. This anarchy has often been put forward as a potential breeding ground for terrorism. As a response to this threat the United States has undertaken several policies, initiatives, and operations in the Horn of Africa generally and in Somalia specifically. In this descriptive study a twofold analysis has been undertaken. First, conditions in present day Somalia as well as Somali history have been analyzed to evaluate the potential Somalia holds as a terrorist base of operations or a recruiting- or staging area. Second, US strategies and actions have been analyzed to evaluate the adequacy of the US response to the threat Somalia poses in terms of terrorism. Material for the analyses have been derived from anthropological, political, and security studies dealing with Somalia. This material has been augmented by a wide range of news coverage, western and non-western. Certain different US policy documents from different levels have been chosen to represent US strategies for the Global War on Terrorism. Because Somali social institutions, such as the clan system, hold great weight in Somali society, Somalia is a difficult area of operations for terrorist networks. In addition the changing nature of Somali alliances and the tangled webs of conflict that characterize present day Somalia aggravate the difficulties that foreign terrorist networks would encounter in Somalia, would they choose to try to utilize it in any great extent. The US has taken potential terrorism threats in Africa and specifically Somalia very seriously. US actions in Somalia have mainly focused on apprehending or neutralizing terror suspects. Such policies, coupled with backing the Ethiopian invasion of Somalia may have actually turned out increasing Somalia’s terror potential.
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Sosialistisen vallankumouksen jälkeen Neuvosto-Venäjän oli monien muiden kysymysten ohella ratkaistava sosialismin saavutusten puolustaminen. Aluksi ratkaisuksi suunniteltiin vapaaehtoisuuteen perustuvaa punakaartia, mutta riittävän miesvahvuuden turvaamiseksi päädyttiin yleiseen asevelvollisuuteen. Pian Venäjän sisällissodan jälkeen sotataidon suunta painottui enemmän vanhan armeijan asiantuntijoiden näkemysten kuin vallankumoussankarien kokemusten mukaiseksi, vaikka Frunzen puna-armeijalle kirjoittama doktriini perustui luokkataisteluun ja korosti sisällissodassa hyväksi koettua operatiivista liikkuvuutta. Neuvostoliiton ja Venäjän sotataidon perustana on Pietari I:n aloittama länsimainen suuntaus, jota kuitenkin täydentävät vahvat kansalliset piirteet. Venäläisen sotataidon henkisenä isänä voidaan hyvällä syyllä pitää Aleksandr Suvorovia, jonka opetukset näkyvät tekstilainausten lisäksi myös periaatteissa ja sotilaskasvatuksessa. Napoleonin sotien jälkeen perustettu Keisarillinen yleisesikunta-akatemia loi Venäjälle sotatieteellisen tutkimuksen ja opetuksen. Sotatieteen mahdollisuuksia ei 1800-luvun Venäjällä osattu täysin hyödyntää. Aseistuksen kasvavan tehon merkitystä vähättelevä asenne johti sotataidon taantumisen ja katastrofiin Venäjän–Japanin sodassa. Sen kokemuksia analysoidessaan Aleksandr Neznamov kehitti edelleen saksalaista operaation käsitettä ja loi perustan Neuvostoliitossa 1920-luvulla kehitetylle operaatiotaidolle. Neuvostoliittolaisen sotataidon päämääränä oli kehittää taktinen ja operatiivinen ratkaisu aseistuksen tehon kasvun aikaansaamaan puolustuksen ylivoimaisuuteen. Ratkaisussa hyödynnettiin brittien kokemuksia ja tutkimusta. Neuvostoliittolainen taktiikka ja operaatiotaito eivät kuitenkaan olleet brittiläisen mekanisoidun sodankäynnin tai saksalaisen salamasodan itäinen kopioita vaan itsenäisiin ratkaisuihin pohjautuvia. Syvän taistelun ja operaation teoriaa kokeiltiin harjoituksissa, ja sitä kehitettiin Stalinin vuoden 1937 puhdistuksiin saakka. Toisen maailmansodan taisteluissa puna-armeija sovelsi alkuvaiheen katastrofin jälkeen syvän taistelun ja syvän operaation oppeja. Komentajien ja joukkojen taito ei riittänyt teorian vaatimusten mukaiseen toimintaan, siksi syväksi aiotusta taistelusta tuli ajoittain ainoastaan tiheää. Suuren isänmaallisen sodan kokemusten perusteella neuvostoliittolainen sotatiede kehitti yleisjoukkojen taistelun periaatteet, jotka ovat säilyneet muuttumattomina nykypäivään saakka. Kylmän sodan aikakaudella ydin- ja tavanomaisen aseistuksen merkitys sodan ja taistelun kuvassa vaihteli. Lännen sotataidon ja aseteknologian kehitys pakotti Neuvostoliiton siirtymään 1980-luvulla sotilaallisessa ajattelussaan hyökkäyksestä puolustukseen. Neuvostoliiton hajoamisen jälkeen Venäjän sotilaallisen turvallisuuden takaajana on ydinaseistus. Yhdysvaltain tavanomainen ilma-avaruushyökkäyskyky vaatii Venäjää kehittämään torjuntajärjestelmiä. Tavanomaisten joukkojen rakentamisessa Venäjä seuraa tarkasti läntisen sotataidon kehittymistä, mutta pitäytyy omaperäisiin ratkaisuihin, joiden kehittämisessä sen vahvalla sotatieteellisellä järjestelmällä ja dialektisen materialismin metodilla on edelleen olennaisen tärkeä merkitys.
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The pathogenesis of fibrosis and the functional features of pressure overload myocardial hypertrophy are still controversial. The objectives of the present study were to evaluate the function and morphology of the hypertrophied myocardium in renovascular hypertensive (RHT) rats. Male Wistar rats were sacrificed at week 4 (RHT4) and 8 (RHT8) after unilateral renal ischemia (Goldblatt II hypertension model). Normotensive rats were used as controls. Myocardial function was analyzed in isolated papillary muscle preparations, morphological features were defined by light microscopy, and myocardial hydroxyproline concentration (HOP) was determined by spectrophotometry. Renal artery clipping resulted in elevated systolic arterial pressure (RHT4: 178 ± 19 mmHg and RHT8: 194 ± 24 mmHg, P<0.05 vs control: 123 ± 7 mmHg). Myocardial hypertrophy was observed in both renovascular hypertensive groups. The myocardial HOP concentration was increased in the RHT8 group (control: 2.93 ± 0.38 µg/mg; RHT4: 3.02 ± 0.40 µg/mg; RHT8: 3.44 ± 0.45 µg/mg of dry tissue, P<0.05 vs control and RHT4 groups). The morphological study demonstrated myocyte necrosis, vascular damage and cellular inflammatory response throughout the experimental period. The increased cellularity was more intense in the adventitia of the arterioles. As a consequence of myocyte necrosis, there was an early, local, conjunctive stroma collapse with disarray and thickening of the argyrophilic interstitial fibers, followed by scarring. The functional data showed an increased passive myocardial stiffness in the RHT4 group. We conclude that renovascular hypertension induces myocyte and arteriole necrosis. Reparative fibrosis occurred as a consequence of the inflammatory response to necrosis. The mechanical behavior of the isolated papillary muscle was normal, except for an early increased myocardial passive stiffness
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Ketamine is believed to reduce airway and pulmonary tissue resistance. The aim of the present study was to determine the effects of ketamine on the resistive, elastic and viscoelastic/inhomogeneous mechanical properties of the respiratory system, lungs and chest wall, and to relate the mechanical data to findings from histological lung analysis in normal animals. Fifteen adult male Wistar rats were assigned randomly to two groups: control (N = 7) and ketamine (N = 8). All animals were sedated (diazepam, 5 mg, ip) and anesthetized with pentobarbital sodium (20 mg/kg, ip) or ketamine (30 mg/kg, ip). The rats were paralyzed and ventilated mechanically. Ketamine increased lung viscoelastic/inhomogeneous pressure (26%) compared to the control group. Dynamic and static elastances were similar in both groups, but the difference was greater in the ketamine than in the control group. Lung morphometry demonstrated dilation of alveolar ducts and increased areas of alveolar collapse in the ketamine group. In conclusion, ketamine did not act at the airway level but acted at the lung periphery increasing mechanical inhomogeneities possibly resulting from dilation of distal airways and alveolar collapse.
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Cellular Ca2+ signals are crucial in the control of most physiological processes, cell injury and programmed cell death through the regulation of a number of Ca2+-dependent enzymes such as phospholipases, proteases, and nucleases. Mitochondria along with the endoplasmic reticulum play pivotal roles in regulating intracellular Ca2+ content. Mitochondria are endowed with multiple Ca2+ transport mechanisms by which they take up and release Ca2+ across their inner membrane. During cellular Ca2+ overload, mitochondria take up cytosolic Ca2+, which in turn induces opening of permeability transition pores and disrupts the mitochondrial membrane potential (Dym). The collapse of Dym along with the release of cytochrome c from mitochondria is followed by the activation of caspases, nuclear fragmentation and cell death. Members of the Bcl-2 family are a group of proteins that play important roles in apoptosis regulation. Members of this family appear to differentially regulate intracellular Ca2+ level. Translocation of Bax, an apoptotic signaling protein, from the cytosol to the mitochondrial membrane is another step in this apoptosis signaling pathway.
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Rounded atelectasis (RA) is a benign and unusual form of subpleural lung collapse that has been described mostly in asbestos-exposed workers. This form of atelectasis manifests as a lung nodule and can be confused with bronchogenic carcinoma upon conventional radiologic examination. The objective of the present study was to evaluate the variation in contrast uptake in computed tomography for the identification of asbestos-related RA in Brazil. Between January 1998 and December 2000, high-resolution computed tomography (HRCT) was performed in 1658 asbestos-exposed workers. The diagnosis was made in nine patients based on a history of prior asbestos exposure, the presence of characteristic (HRCT) findings and lesions unchanged in size over 2 years or more. In three of them the diagnosis was confirmed during surgery. The dynamic contrast enhancement study was modified to evaluate nodules and pulmonary masses. All nine patients with RA received iodide contrast according to weight. The average enhancement after iodide contrast was infused, reported as Hounsfield units (HU), increased from 62.5 ± 9.7 to 125.4 ± 20.7 (P < 0.05), with a mean enhancement of 62.5 ± 19.7 (range 40 to 89) and with a uniform dense opacification. In conclusion, in this study all patients with RA showed contrast enhancement with uniform dense opacification. The main clinical implication of this finding is that this procedure does not permit differentiation between RA and malignant pulmonary neoplasm.
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The bedrock of old crystalline cratons is characteristically saturated with brittle structures formed during successive superimposed episodes of deformation and under varying stress regimes. As a result, the crust effectively deforms through the reactivation of pre-existing structures rather than by through the activation, or generation, of new ones, and is said to be in a state of 'structural maturity'. By combining data from Olkiluoto Island, southwestern Finland, which has been investigated as the potential site of a deep geological repository for high-level nuclear waste, with observations from southern Sweden, it can be concluded that the southern part of the Svecofennian shield had already attained structural maturity during the Mesoproterozoic era. This indicates that the phase of activation of the crust, i.e. the time interval during which new fractures were generated, was brief in comparison to the subsequent reactivation phase. Structural maturity of the bedrock was also attained relatively rapidly in Namaqualand, western South Africa, after the formation of first brittle structures during Neoproterozoic time. Subsequent brittle deformation in Namaqualand was controlled by the reactivation of pre-existing strike-slip faults.In such settings, seismic events are likely to occur through reactivation of pre-existing zones that are favourably oriented with respect to prevailing stresses. In Namaqualand, this is shown for present day seismicity by slip tendency analysis, and at Olkiluoto, for a Neoproterozoic earthquake reactivating a Mesoproterozoic fault. By combining detailed field observations with the results of paleostress inversions and relative and absolute time constraints, seven distinctm superimposed paleostress regimes have been recognized in the Olkiluoto region. From oldest to youngest these are: (1) NW-SE to NNW-SSE transpression, which prevailed soon after 1.75 Ga, when the crust had sufficiently cooled down to allow brittle deformation to occur. During this phase conjugate NNW-SSE and NE-SW striking strike-slip faults were active simultaneous with reactivation of SE-dipping low-angle shear zones and foliation planes. This was followed by (2) N-S to NE-SW transpression, which caused partial reactivation of structures formed in the first event; (3) NW-SE extension during the Gothian orogeny and at the time of rapakivi magmatism and intrusion of diabase dikes; (4) NE-SW transtension that occurred between 1.60 and 1.30 Ga and which also formed the NW-SE-trending Satakunta graben located some 20 km north of Olkiluoto. Greisen-type veins also formed during this phase. (5) NE-SW compression that postdates both the formation of the 1.56 Ga rapakivi granites and 1.27 Ga olivine diabases of the region; (6) E-W transpression during the early stages of the Mesoproterozoic Sveconorwegian orogeny and which also predated (7) almost coaxial E-W extension attributed to the collapse of the Sveconorwegian orogeny. The kinematic analysis of fracture systems in crystalline bedrock also provides a robust framework for evaluating fluid-rock interaction in the brittle regime; this is essential in assessment of bedrock integrity for numerous geo-engineering applications, including groundwater management, transient or permanent CO2 storage and site investigations for permanent waste disposal. Investigations at Olkiluoto revealed that fluid flow along fractures is coupled with low normal tractions due to in-situ stresses and thus deviates from the generally accepted critically stressed fracture concept, where fluid flow is concentrated on fractures on the verge of failure. The difference is linked to the shallow conditions of Olkiluoto - due to the low differential stresses inherent at shallow depths, fracture activation and fluid flow is controlled by dilation due to low normal tractions. At deeper settings, however, fluid flow is controlled by fracture criticality caused by large differential stress, which drives shear deformation instead of dilation.
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Toxic cyanobacteria in drinking water supplies can cause serious public health problems. In the present study we analyzed the time course of changes in lung histology in young and adult male Swiss mice injected intraperitoneally (ip) with a cyanobacterial extract containing the hepatotoxic microcystins. Microcystins are cyclical heptapeptides quantified by ELISA method. Ninety mice were divided into two groups. Group C received an injection of saline (300 µl, ip) and group Ci received a sublethal dose of microcystins (48.2 µg/kg, ip). Mice of the Ci group were further divided into young (4 weeks old) and adult (12 weeks old) animals. At 2 and 8 h and at 1, 2, 3, and 4 days after the injection of the toxic cyanobacterial extract, the mice were anesthetized and the trachea was occluded at end-expiration. The lungs were removed en bloc, fixed, sectioned, and stained with hematoxylin-eosin. The percentage of the area of alveolar collapse and the number of polymorphonuclear (PMN) and mononuclear cell infiltrations were determined by point counting. Alveolar collapse increased from C to all Ci groups (123 to 262%) independently of time, reaching a maximum value earlier in young than in adult animals. The amount of PMN cells increased with time of the lesion (52 to 161%). The inflammatory response also reached the highest level earlier in young than in adult mice. After 2 days, PMN levels remained unchanged in adult mice, while in young mice the maximum number was observed at day 1 and was similar at days 2, 3, and 4. We conclude that the toxins and/or other cyanobacterial compounds probably exert these effects by reaching the lung through the blood stream after ip injection.
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The pressure sensitivities of the near infrared spectra of the light-harvesting (LH2) complex and a mutant complex with a simplified BChl-B850 binding pocket were compared. In the mutant an abrupt change in the spectral properties occurred at 250 MPa, which was not observed with the native sample. Increased disorder due to collapse of the chromophore pocket is suggested.
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The aim of the present study was to compare the efficacy of a novel phosphodiesterase 4 and 5 inhibitor, LASSBio596, with that of dexamethasone in a murine model of chronic asthma. Lung mechanics (airway resistance, viscoelastic pressure, and static elastance), histology, and airway and lung parenchyma remodeling (quantitative analysis of collagen and elastic fiber) were analyzed. Thirty-three BALB/c mice were randomly assigned to four groups. In the asthma group (N = 9), mice were immunized with 10 µg ovalbumin (OVA, ip) on 7 alternate days, and after day 40 they were challenged with three intratracheal instillations of 20 µg OVA at 3-day intervals. Control mice (N = 8) received saline under the same protocol. In the dexamethasone (N = 8) and LASSBio596 (N = 8) groups, the animals of the asthma group were treated with 1 mg/kg dexamethasone disodium phosphate (0.1 mL, ip) or 10 mg/kg LASSBio596 dissolved in dimethyl sulfoxide (0.2 mL, ip) 24 h before the first intratracheal instillation of OVA, for 8 days. Airway resistance, viscoelastic pressure and static elastance increased significantly in the asthma group (77, 56, and 76%, respectively) compared to the control group. The asthma group presented more intense alveolar collapse, bronchoconstriction, and eosinophil and neutrophil infiltration than the control group. Both LASSBio596 and dexamethasone inhibited the changes in lung mechanics, tissue cellularity, bronchoconstriction, as well as airway and lung parenchyma remodeling. In conclusion, LASSBio596 at a dose of 10 mg/kg effectively prevented lung mechanical and morphometrical changes and had the potential to block fibroproliferation in a BALB/c mouse model of asthma.
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This study investigated the in vitro and in vivo antiproliferative activity of esculetin against hepatocellular carcinoma, and clarified its potential molecular mechanisms. Cell viability was determined by the MTT (tetrazolium) colorimetric assay. In vivoantitumor activity of esculetin was evaluated in a hepatocellular carcinoma mouse model. Seventy-five C57BL/6J mice were implanted with Hepa1-6 cells and randomized into five groups (n=15 each) given daily intraperitoneal injections of vehicle (physiological saline), esculetin (200, 400, or 700 mg·kg-1·day-1), or 5-Fu (200 mg·kg-1·day-1) for 15 days. Esculetin significantly decreased tumor growth in mice bearing Hepa1-6 cells. Tumor weight was decreased by 20.33, 40.37, and 55.42% with increasing doses of esculetin. Esculetin significantly inhibited proliferation of HCC cells in a concentration- and time-dependent manner and with an IC50 value of 2.24 mM. It blocked the cell cycle at S phase and induced apoptosis in SMMC-7721 cells with significant elevation of caspase-3 and caspase-9 activity, but did not affect caspase-8 activity. Moreover, esculetin treatment resulted in the collapse of mitochondrial membrane potential in vitro and in vivo accompanied by increased Bax expression and decreased Bcl-2 expression at both transcriptional and translational levels. Thus, esculetin exerted in vitro and in vivo antiproliferative activity in hepatocellular carcinoma, and its mechanisms involved initiation of a mitochondrial-mediated, caspase-dependent apoptosis pathway.
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Symbolic dynamics is a branch of mathematics that studies the structure of infinite sequences of symbols, or in the multidimensional case, infinite grids of symbols. Classes of such sequences and grids defined by collections of forbidden patterns are called subshifts, and subshifts of finite type are defined by finitely many forbidden patterns. The simplest examples of multidimensional subshifts are sets of Wang tilings, infinite arrangements of square tiles with colored edges, where adjacent edges must have the same color. Multidimensional symbolic dynamics has strong connections to computability theory, since most of the basic properties of subshifts cannot be recognized by computer programs, but are instead characterized by some higher-level notion of computability. This dissertation focuses on the structure of multidimensional subshifts, and the ways in which it relates to their computational properties. In the first part, we study the subpattern posets and Cantor-Bendixson ranks of countable subshifts of finite type, which can be seen as measures of their structural complexity. We show, by explicitly constructing subshifts with the desired properties, that both notions are essentially restricted only by computability conditions. In the second part of the dissertation, we study different methods of defining (classes of ) multidimensional subshifts, and how they relate to each other and existing methods. We present definitions that use monadic second-order logic, a more restricted kind of logical quantification called quantifier extension, and multi-headed finite state machines. Two of the definitions give rise to hierarchies of subshift classes, which are a priori infinite, but which we show to collapse into finitely many levels. The quantifier extension provides insight to the somewhat mysterious class of multidimensional sofic subshifts, since we prove a characterization for the class of subshifts that can extend a sofic subshift into a nonsofic one.
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Introduction: The potential risks related to drug exposure during pregnancy represent a vast chapter in modern obstetrics and data regarding the safety of antihypertensive drugs during pregnancy are relatively scarce. Case report: A 37-year-old patient discovered her fifth pregnancy at our hospital after 26 weeks and 4 days of gestation. She reported a history of hypertension and was currently being treated with Losartan. Hospitalization was recommended for the patient and further evaluation of fetal vitality was performed. On the fourth day an ultrasound was performed, resulting in a severe oligohydramnios, fetal centralization and abnormal ductus venosus. After 36 hours, the newborn died. Pathologic evaluation: At autopsy, the skullcap had large fontanels and deficient ossification. The kidneys were slightly enlarged. A microscopic examination detected underdevelopment of the tubules and the presence of some dilated lumens. Immunohistochemical detection of epithelial membrane antigen was positive. Immunoreactivity of CD 15 was also assayed to characterize the proximal tubules, and lumen collapse was observed in some regions. Discussion: Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor antagonists (ARAs) are among the most widely prescribed drugs for hypertension. They are often used by hypertensive women who are considering become pregnant. While their fetal toxicity in the second or third trimesters has been documented, their teratogenic effect during the first trimester has only recently been demonstrated. Conclusion: Constant awareness by physicians and patients should be encouraged, particularly in regard to the prescription of antihypertensive drugs in women of childbearing age who are or intend to become pregnant.