血小板激活因子对大鼠脑血管通透性的影响及药物的保护作用

颈内动脉注射血小板激活因子(PAF),再给伊文思蓝,可见脑实质染色程度加深,而颈内动脉只注射伊文思蓝,脑实质未见染色。而我们合成的新药SZ-1可剂量依赖性地抑制PAF诱导的脑实质伊文思蓝染色程度的加深。在体外培养的脑微血管平滑肌细胞上,PAF能显著刺激~(14)-花生四烯酸的释放,而SZ-1能剂量依赖性地抑制这种释放,提示PAF在脑内产生的损害除与其他因素相关外,还与其刺激花生四烯酸释放有密切关系,SZ-1对PAF引起的脑部损害有保护作用。     

Adolescent pregnancy--current trends and issues: 1998 American Academy of Pediatrics Committee on Adolescence, 1998-1999

Although the prevention of unintended adolescent pregnancy is a primary goal of the American Academy of Pediatrics and society, many adolescents continue to become pregnant. Since the last statement on adolescent pregnancy was issued by the Academy in 1989, new observations have been recorded in the literature. The purpose of this new statement is to review current trends and issues on adolescent pregnancy to update practitioners on this topic.     

Planning for children whose parents are dying of HIV/AIDS. American Academy of Pediatrics. Committee on Pediatric AIDS, 1998-1999

Although the character of acquired immunodeficiency syndrome is changing into a chronic illness, it is estimated that by the end of this century, 80 000 children and adolescents in the United States will be orphaned by parental death caused by human immunodeficiency virus infection. Plans for these children need to be made to ensure not only a stable, consistent environment that provides love and nurturing, but also the medical and social interventions necessary to cope with the tragic loss. Pediatricians should become aware of local laws and community resources and initiate discussion early in the course of parental illness to facilitate planning for the future care and custody of the children. States need to adopt laws and regulations that provide flexible approaches to guardianship and placement of children orphaned by acquired immunodeficiency syndrome.     

A study to the fibroblast—populated collagen lattices

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肠源性内毒素血症与肝病

近年来,肠源性内毒素血症(intestinal endotoxemia,IETM)与肝病的关系日益受到重视.临床观察表明,各种急、慢性肝炎、肝硬变和重型肝炎患者内毒素血症(endotoxemia,ETM)发生率有不同程度升高.内毒素与肝损害之间存在着密切的关系[1-3].二者可互为因果,从而对肝病的发生发展产生重要影响.特别是内毒素作用于肝脏后,引起多种细胞因子分泌与释放,导致肝脏损害进一步加重,甚至出现黄疸、出血、肾功能衰竭与肝性脑病等肝功能衰竭临床综合征.     

Serial lung scintigraphy: utility in diagnosis of pulmonary embolism

Pairs of sequential perfusion lung scans and pulmonary angiograms obtained in 45 patients were reviewed to investigate the utility of short-term, sequential scintigraphy in the diagnosis of pulmonary embolism (PE). Forty-six sequential scan pairs were reviewed; 13 were ventilation-perfusion (V-P) pairs. Angiograms were obtained within 48 hours of either the first (65%) or second (35%) perfusion scan in each pair. Sequential scintigraphic patterns were classified as showing change (i.e., improvement in defects, new defects), no change, or as being indeterminate. A changing perfusion pattern was associated with a high (20/23) likelihood of PE, but seven of 16 patients with stable perfusion patterns also had PE. The sensitivity of a changing perfusion pattern for PE was 0.74 (20/27) and its specificity was 0.75 (9/12). In two of six patients who had serial V-P studies that showed changing perfusion defects, there were matched changes in regional ventilation and angiograms were negative. The findings suggest that short-term serial perfusion lung scanning may aid the scintigraphic diagnosis of PE in certain circumstances. Serial V-P imaging is needed, however, to maximize diagnostic specificity.     

山莨菪碱和蝙蝠葛碱对白三烯和PAF诱导的牛脑前动脉平滑肌细胞DNA合成的影响(英文)

白三烯和血小板活化因子在低于nmol浓度时就能刺激培养的牛脑前动脉平滑肌细胞的DNA合成,在10^-7mol/L时达最大刺激。LTB₄,LTD₄和PAF在10^-7mol/L时对上述细胞DNA合成的刺激率分别为32%,29%和77%。山莨菪碱和蝙蝠葛碱在10^-7～10^-4mol/L范围内呈剂量依赖性地抑制白三烯和血小板活化因子的上述作用。     

Morphogenesis underlying the development of the everted teleost telencephalon

Background

In dorsal spinal neurons and monocytes, bone morphogenetic protein (BMP)7 activates distinct transduction pathways, one leading to inductive specification and the other to axon orientation and chemotaxis. BMP7-evoked induction, also stimulated by the closely related BMP6, acts through a Smad cascade, leading to nuclear signaling, and is not BMPR subunit selective. Orientation is evoked by BMP7, but not by BMP6, through PI3K-dependent cytoskeletal activation mediated by the type II BMPRs, ActRIIA and BMPRII and is independent of the Smad cascade. The responses can be stimulated concurrently and suggest that BMP7, but not BMP6, can selectively activate BMPR subunits that engage the divergent paths. Although structural and biochemical analyses of selected BMP/BMPR interfaces have identified key regions of interaction, how these translate into function by related BMPs is poorly understood. To determine the mechanisms underlying the distinct activities of BMP7 and the disparate properties of BMP7 and BMP6 in spinal cord development, we have performed a family-wide structure/function analysis of BMPs and used the information to predict and test sites within BMPs that may control agonist properties, in particular the ability of a BMP to orient axons, through interactions with BMPRs.

Results

We demonstrate that whereas all BMPs can induce dorsal neurons, there is selectivity in the ability also to orient axons or evoke growth cone collapse. The degree to which a BMP orients is not predictable by overall protein similarity with other BMPs but comparison of sequences of potent and weakly orienting BMPs with that of the non-orienting BMP6 revealed three candidate positions within the BMPs at which the amino acid residues may confer or obstruct orienting ability. Residue swapping analysis has identified one residue, Gln ⁴⁸ in BMP6, that blocks axon orienting ability. Replacing Gln ⁴⁸ with any of the amino acids present at the equivalent residue position in the orienting subset of BMPs confers orienting activity on BMP6. Conversely, swapping Gln ⁴⁸ into BMP7 reduces orienting ability. The inductive capacity of the BMPs was unchanged by these residue swaps.

Conclusions

The results suggest that the presence of the Gln ⁴⁸ residue in BMP6 is structurally inhibitory for BMP/BMPR interactions that result in the activation of intracellular signaling, leading to axon orientation. Moreover, since residue 48 in BMP7 and the corresponding residue in BMP2 are important for type II BMPR binding, our results provide a basis for a mechanistic understanding of the diverse activities of BMPs in spinal cord development.     

Ia antigen is a differentiation marker on human eosinophils

Evidence suggests that the "la-like" or antigen is a differentiation marker that is expressed on early human hematopoietic precursor cells, but is absent on their mature progeny. The eosinophil precursor cell (CFU-EO) is distinct from the granulocyte-monocyte colon-forming cell (CFU-C). We provide data that indicate that the ia antigen is expressed on the human eosinophil colony-forming cells and is absent on mature eosinophils. All CFU-EO were inhibited in the presence of rabbit la antiserum at a titer of 1:30. Cytotoxicity was complement-dependent. The metamyelocytic eosinophil and more mature eosinophil forms did not express the la antigen.