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排序方式: 共有235条查询结果,搜索用时 343 毫秒
91.
Obstetrical magnetic resonance imaging: maternal anatomy 总被引:4,自引:1,他引:3
Eleven patients whose pregnancies were at 34-36 weeks of gestational development underwent magnetic resonance (MR) imaging. Images of the maternal pelvis were assessed for anatomical changes of pregnancy in comparison with MR images of five non-pregnant volunteers. The relationship of the fetal presenting part to the internal os of the cervix was seen in all patients. Effacement of the cervix was identified when present. The maternal spine demonstrated disk abnormalities in nine patients. Changes in venous flow patterns were readily identified in all patients. The inferior vena cava was flattened or obliterated, a high signal was present in the iliac vessels (TE 56), and large collateral vessels were present. 相似文献
92.
93.
FimA, a major virulence factor associated with Streptococcus parasanguis endocarditis. 总被引:3,自引:4,他引:3
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D Burnette-Curley V Wells H Viscount C L Munro J C Fenno P Fives-Taylor F L Macrina 《Infection and immunity》1995,63(12):4669-4674
Adherence of microorganisms to damaged heart tissue is a crucial event in the pathogenesis of infective endocarditis. In the present study, we investigated the role of the FimA protein as a potential virulence factor associated with Streptococcus parasanguis endocarditis. FimA is a 36-kDa surface protein that is a recognized adhesin in the oral cavity where it mediates adherence to the salivary pellicle. An insertion mutant and a deletion mutant of S. parasanguis were employed in the rat model of endocarditis to determine the relevance of FimA in endocarditis pathogenesis. Catheterized rats were infected with either the fimA deletion mutant VT929, the fimA insertion mutant VT930, or the isogenic, wild-type S. parasanguis FW213. Rats inoculated with FW213 developed endocarditis more frequently (50.9%) than animals inoculated with either the deletion mutant (2.7%) or the insertion mutant (7.6%) (P < 0.001). A series of in vitro assays were performed to explore the mechanism(s) by which FimA enhanced the infectivity of S. parasanguis. FimA did not inhibit the uptake or the subsequent killing of S. parasanguis by phagocytic granulocytes. Similarly, FimA did not play a role in the adherence to or the aggregation of platelets. Significant differences were noted between FW213 and VT929 (P < 0.05) and FW213 and VT930 (P < 0.001) in their abilities to bind to fibrin monolayers. The mean percent adherence of FW213 to fibrin monolayers (2.1%) was greater than those of VT929 (0.5%) and VT930 (0.12%). Taken together, these results indicate that FimA is a major virulence determinant associated with S. parasanguis endocarditis and further suggest that its role is associated with initial colonization of damaged heart tissue. 相似文献
94.
Initiation of growth of baboon primordial follicles in vitro 总被引:5,自引:2,他引:5
Wandji SA; Srsen V; Nathanielsz PW; Eppig JJ; Fortune JE 《Human reproduction (Oxford, England)》1997,12(9):1993-2001
Factors that cause some primordial follicles to enter the growth phase
while the others remain quiescent are unknown. The hypothesis was tested
that primate primordial follicles can survive and initiate growth in vitro
in serum-free medium. Superficial pieces of ovarian cortex, containing
mostly primordial follicles, were obtained from baboon fetuses during late
gestation and cultured for 0, 2, 4, 7, 10 or 20 days in Waymouth MB 752/1
medium supplemented with insulin, transferrin, selenium, linoleic acid, and
bovine serum albumin (ITS +). Histological examination of cortical pieces
revealed that after 2 and 4 days in culture, the total number of primordial
follicles had decreased by 55 and 76% (P < 0.01) respectively, relative
to day 0 of culture. This was associated with a sustained, 5- to 8-fold
increase in total primary follicles (P < 0.01) beginning on day 2 of
culture. There was also a gradual increase in the total number of early
secondary and secondary follicles. The average diameter of follicles and
oocytes increased gradually throughout culture for all follicular
categories (P < 0.01), except secondary follicles and oocytes.
Immunohistochemical localization of proliferating cell nuclear antigen
(PCNA), a marker for cell proliferation and growth, showed that PCNA was
generally absent in primordial follicles on day 0, but was observed after 2
or 4 days in culture in both granulosa cells and oocytes of most growing
follicles. Comparison of cortical pieces cultured for 10 or 20 days with
ITS + versus 10% fetal bovine serum (FBS) showed a more pronounced decrease
in the numbers of primordial follicles and more primary, early secondary
and secondary follicles in ITS + compared to FBS-treated cortical pieces (P
< 0.01 at 20 days). These results show that primordial follicles from
non-human primates can survive and develop to the secondary stage in vitro
in serum-free conditions.
相似文献
95.
96.
Daniel S Martin Maryam Khosravi Mike PW Grocott Michael G Mythen 《Critical care (London, England)》2010,14(4):315
The human fetus develops in a profoundly hypoxic environment. Thus, the foundations of our physiology are built in the most
hypoxic conditions that we are ever likely to experience: the womb. This magnitude of exposure to hypoxia in utero is rarely experienced in adult life, with few exceptions, including severe pathophysiology in critical illness and environmental
hypobaric hypoxia at high altitude. Indeed, the lowest recorded levels of arterial oxygen in adult humans are similar to those
of a fetus and were recorded just below the highest attainable elevation on the Earth's surface: the summit of Mount Everest.
We propose that the hypoxic intrauterine environment exerts a profound effect on human tolerance to hypoxia. Cellular mechanisms
that facilitate fetal well-being may be amenable to manipulation in adults to promote survival advantage in severe hypoxemic
stress. Many of these mechanisms act to modify the process of oxygen consumption rather than oxygen delivery in order to maintain
adequate tissue oxygenation. The successful activation of such processes may provide a new chapter in the clinical management
of hypoxemia. Thus, strategies employed to endure the relative hypoxia in utero may provide insights for the management of severe hypoxemia in adult life and ventures to high altitude may yield clues to
the means by which to investigate those strategies. 相似文献
97.
98.
Ahilanandan Dushianthan Rebecca Cusack Victoria Goss Anthony D Postle Mike PW Grocott 《Critical care (London, England)》2012,16(6):1-11
Acute lung injury and acute respiratory distress syndrome (ARDS) are characterised by severe hypoxemic respiratory failure and poor lung compliance. Despite advances in clinical management, morbidity and mortality remains high. Supportive measures including protective lung ventilation confer a survival advantage in patients with ARDS, but management is otherwise limited by the lack of effective pharmacological therapies. Surfactant dysfunction with quantitative and qualitative abnormalities of both phospholipids and proteins are characteristic of patients with ARDS. Exogenous surfactant replacement in animal models of ARDS and neonatal respiratory distress syndrome shows consistent improvements in gas exchange and survival. However, whilst some adult studies have shown improved oxygenation, no survival benefit has been demonstrated to date. This lack of clinical efficacy may be related to disease heterogeneity (where treatment responders may be obscured by nonresponders), limited understanding of surfactant biology in patients or an absence of therapeutic effect in this population. Crucially, the mechanism of lung injury in neonates is different from that in ARDS: surfactant inhibition by plasma constituents is a typical feature of ARDS, whereas the primary pathology in neonates is the deficiency of surfactant material due to reduced synthesis. Absence of phenotypic characterisation of patients, the lack of an ideal natural surfactant material with adequate surfactant proteins, coupled with uncertainty about optimal timing, dosing and delivery method are some of the limitations of published surfactant replacement clinical trials. Recent advances in stable isotope labelling of surfactant phospholipids coupled with analytical methods using electrospray ionisation mass spectrometry enable highly specific molecular assessment of phospholipid subclasses and synthetic rates that can be utilised for phenotypic characterisation and individualisation of exogenous surfactant replacement therapy. Exploring the clinical benefit of such an approach should be a priority for future ARDS research. 相似文献
99.
100.
Both CD80 and CD86 co-stimulatory molecules regulate allergic pulmonary inflammation 总被引:2,自引:0,他引:2
Mark DA; Donovan CE; De Sanctis GT; Krinzman SJ; Kobzik L; Linsley PS; Sayegh MH; Lederer J; Perkins DL; Finn PW 《International immunology》1998,10(11):1647-1655
We examined the roles of CD80 (B7-1) and CD86 (B7-2) in a model of allergic
pulmonary inflammation and airway hyper-responsiveness (AHR) by selectively
inhibiting either CD80 or CD86. Inhibition of co- stimulation by either
CD80 or CD86 affected multiple parameters of the allergic response.
Specifically, blockade of either CD80 or CD86 in ovalbumin-sensitized and
challenged mice resulted in reduced expression of IL-2Ralpha (CD25) on CD4+
T lymphocytes, decreased airway eosinophilia, lower serum IgE production
and diminished AHR. Importantly, blockade of CD80 and CD86 inhibited
production of IL-4 and IL-2, and enhanced IFN-gamma production. Our
observations support a role for both CD80- and CD86-mediated co-stimulation
in development of allergic pulmonary inflammation.
相似文献