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991.
The pathogenesis of enteropathogenic Escherichia coli (EPEC) infection is emerging as a paradigm for a multistage microorganism-host cell interaction. Both type IV fimbriae and a type III secretion apparatus play principal roles in interactions between the bacteria and host cells. Recent data suggest that bacteria-induced signal transduction activates the receptor that allows tenacious adherence of the bacteria to the host cell surface.  相似文献   
992.
PURPOSE: The authors document the association of peripapillary staphyloma and an atypical variant of hemimegalencephaly with the linear nevus sebaceous syndrome. BACKGROUND: Linear nevus sebaceous syndrome is an uncommon neurocutaneous disorder that has a propensity to involve the eyes. METHODS: Clinical, histopathologic, and neuroimaging findings are examined in a child with linear nevus sebaceous syndrome. RESULTS: In addition to bilateral peripapillary staphylomas, ophthalmologic abnormalities included a corneal dermoid, a complex conjunctival choristoma, macular hypoplasia, and optic nerve hypoplasia with contralateral optic atrophy. Magnetic resonance imaging disclosed a rare form of hemimegalencephaly characterized by hypoplasia of an optic radiation within the enlarged, dysgenetic cerebral hemisphere. CONCLUSION: The spectrum of oculocerebral dysgenesis in the linear nevus sebaceous syndrome can be expanded to include peripapillary staphyloma and atypical hemimegalencephaly with hypoplasia of an optic radiation.  相似文献   
993.
Stroke and head trauma are worldwide public health problems and leading causes of death and disability in humans, yet, no adequate neuroprotective treatment is available for therapy. Glutamate antagonists are considered major drug candidates for neuroprotection in stroke and trauma. However, N-methyl-D-aspartate antagonists failed clinical trials because of unacceptable side effects and short therapeutic time window. alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) antagonists derived from the quinoxalinedione scaffold cannot be used in humans because of their insolubility and resulting renal toxicity. Therefore, achieving water solubility of quinoxalinediones without loss of selectivity and potency profiles becomes a major challenge for medicinal chemistry. One of the major tenets in the chemistry of glutamate antagonists is that the incorporation of phosphonate into the glutamate framework results in preferential N-methyl-D-aspartate antagonism. Therefore, synthesis of phosphonate derivatives of quinoxalinediones was not pursued because of a predicted loss of their selectivity toward AMPA. Here, we report that introduction of a methylphosphonate group into the quinoxalinedione skeleton leaves potency as AMPA antagonists and selectivity for the AMPA receptor unchanged and dramatically improves solubility. One such novel phosphonate quinoxalinedione derivative and competitive AMPA antagonist ZK200775 exhibited a surprisingly long therapeutic time window of >4 h after permanent occlusion of the middle cerebral artery in rats and was devoid of renal toxicity. Furthermore, delayed treatment with ZK200775 commencing 2 h after onset of reperfusion in transient middle cerebral artery occlusion resulted in a dramatic reduction of the infarct size. ZK200775 alleviated also both cortical and hippocampal damage induced by head trauma in the rat. These observations suggest that phosphonate quinoxalinedione-based AMPA antagonists may offer new prospects for treatment of stroke and trauma in humans.  相似文献   
994.
Vascular endothelial growth factor (VEGF) plays a key role in physiological blood vessel formation and pathological angiogenesis such as tumor growth and ischemic diseases. Hypoxia is a potent inducer of VEGF in vitro. Here we demonstrate that VEGF is induced in vivo by exposing mice to systemic hypoxia. VEGF induction was highest in brain, but also occurred in kidney, testis, lung, heart, and liver. In situ hybridization analysis revealed that a distinct subset of cells within a given organ, such as glial cells and neurons in brain, tubular cells in kidney, and Sertoli cells in testis, responded to the hypoxic stimulus with an increase in VEGF expression. Surprisingly, however, other cells at sites of constitutive VEGF expression in normal adult tissues, such as epithelial cells in the choroid plexus and kidney glomeruli, decreased VEGF expression in response to the hypoxic stimulus. Furthermore, in addition to VEGF itself, expression of VEGF receptor-1 (VEGFR-1), but not VEGFR-2, was induced by hypoxia in endothelial cells of lung, heart, brain, kidney, and liver. VEGF itself was never found to be up-regulated in endothelial cells under hypoxic conditions, consistent with its paracrine action during normoxia. Our results show that the response to hypoxia in vivo is differentially regulated at the level of specific cell types or layers in certain organs. In these tissues, up- or down-regulation of VEGF and VEGFR-1 during hypoxia may influence their oxygenation after angiogenesis or modulate vascular permeability.  相似文献   
995.
The immunosuppressive and antiinflammatory cytokine interleukin (IL) 10 selectively upregulates the expression of the CC chemokine receptors CCR5, 2, and 1 in human monocytes by prolonging their mRNA half-life. IL-10-stimulated monocytes display an increased number of cell surface receptors for, and better chemotactic responsiveness to, relevant agonists than do control cells. In addition, IL-10-stimulated monocytes are more efficiently infected by HIV BaL. This effect was associated to the enhancement of viral entry through CCR5. These data add support to an emerging paradigm in which pro- and antiinflammatory molecules exert reciprocal and opposing influence on chemokine agonist production and receptor expression.  相似文献   
996.
Hemorrhagic cystitis is a potentially life-threatening complication in systemic lupus erythematosus (SLE). No safe, effective and conservative treatment exists for patients who fail to respond to standard therapy. We report a 17-year-old girl with SLE who suffered from severe hemorrhagic cystitis. Initially, she received frequent red blood cell and platelet transfusions, continuous bladder irrigation, and blood clots were evacuated. Numerous kinds of treatment were tried, including electrocoagulation of bleeding foci, prostaglandin E1 bladder instillation, and hyperbaric oxygen. However, she remained severely anemic and thrombocytopenic necessitating daily transfusions of blood products. After intravesical formalin instillation was performed twice, the hematuria ceased completely.  相似文献   
997.
This supplement reports the characterization of 15 new Salmonella serovars recognized in 1997 by the WHO Collaborating Centre for Reference and Research on Salmonella: 8 were assigned to S. enterica subsp. enterica, 4 to subspecies salamae, 2 to subspecies diarizonae, and 1 to subsp. houtenae. In addition, the antigenic factors H:z85 and H:z87 are described and one modification to the Kauffmann-White scheme is reported.  相似文献   
998.
A key problem in recognition is that the image of an object depends on the lighting conditions. We investigated whether recognition is sensitive to illumination using 3-D objects that were lit from either the left or right, varying both the shading and the cast shadows. In experiments 1 and 2 participants judged whether two sequentially presented objects were the same regardless of illumination. Experiment 1 used six objects that were easily discriminated and that were rendered with cast shadows. While no cost was found in sensitivity, there was a response time cost over a change in lighting direction. Experiment 2 included six additional objects that were similar to the original six objects making recognition more difficult. The objects were rendered with cast shadows, no shadows, and as a control, white shadows. With normal shadows a change in lighting direction produced costs in both sensitivity and response times. With white shadows there was a much larger cost in sensitivity and a comparable cost in response times. Without cast shadows there was no cost in either measure, but the overall performance was poorer. Experiment 3 used a naming task in which names were assigned to six objects rendered with cast shadows. Participants practised identifying the objects in two viewpoints lit from a single lighting direction. Viewpoint and illumination invariance were then tested over new viewpoints and illuminations. Costs in both sensitivity and response time were found for naming the familiar objects in unfamiliar lighting directions regardless of whether the viewpoint was familiar or unfamiliar. Together these results suggest that illumination effects such as shadow edges: (1) affect visual memory; (2) serve the function of making unambigous the three-dimensional shape; and (3) are modeled with respect to object shape, rather than simply encoded in terms of their effects in the image.  相似文献   
999.
Symptomatic neurocysticercosis, a major cause of epilepsy worldwide, results from inflammation around Taenia solium larvae, but the mechanisms are unknown. Eotaxin, not previously reported in cases of human infection, and interleukin-5 (IL-5) but not IL-8 concentrations were elevated in patient serum, and IL-5 levels were also elevated in cerebrospinal fluid (CSF). Eosinophil-selective mediators may be involved in the pathogenesis of cysticercosis. IL-6 concentrations were also elevated in patient CSF, possibly indicative of an acute-phase response.  相似文献   
1000.
Between 1988 and 1995, 32 knee joints (29 patients) with hemophilic arthropathy underwent arthroscopy. The spectrum of procedures ranged from resection of fibrous plicae to synovectomy. Technical difficulties appeared in cases of scarred fixed patella, pronounced posterior tibia subluxation, and severe fibrous ankylosis. All operations done between 1988 and 1991 (23 operations; 21 patients) were reviewed retrospectively. The mean age of the patients in this series was 30 years and the mean followup was 5 years. On subjective evaluation, 13 operations achieved a definite improvement, five showed slight improvement, and two had no improvement (three operations were excluded). Arthroscopic surgery, as a relatively low risk technique, combined with early functional rehabilitation, can be used to achieve satisfactory results in patients with hemophilic arthropathy.  相似文献   
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