Relative motion of lung and chest wall promotes uniform pleural space thickness

The pleural space is modeled in two dimensions as a thin layer of fluid separating a deformable membrane and a rigid surface containing a bump. We computed the steady-state membrane configuration and fluid pressure distribution during relative sliding of the two surfaces. For physiologically relevant values of membrane tension, shear flow-induced pressures near the bump and far-field pressure gradients are similar to those measured in vivo within the pleural space (e.g. Lai-Fook et al.) [J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 56 (1984) 1633-1639]. Deformation of the membrane over the bump suggests that the pressure field generated by the sliding motion promotes an even layer of fluid in the pleural space, preventing asperities from touching. Results also suggest a possible mechanism for pleural fluid redistribution during breathing, whereby irreversible fluid motion is associated with the deformability of the membrane.     

中德外科及基础病理新进展研讨会会议简介

由中、德科学中心发起、浙江大学与德国柏林洪堡大学共同主办的中德外科及基础病理新进展研讨会于2004年4月20日～22日在浙江省杭州市举行。会议由浙江大学来茂德教授和德国Humboldt大学Dietel教授主持,中、德两国共23名病理学专家参加了此次高水准国际病理学会议。会议主要涉及WHO肿瘤新分类、第6版国际抗癌联盟(UICC)TNM分期以及SARS病研究等。会议促进了双方病理学界的交流,增进了友谊,为今后中、德两国病理学界的进一步交流、合作开创了新局面。     

Role of bacterial products in periodontitis: immune response in gnotobiotic rats monoinfected with Eikenella corrodens.

The development of humoral and cell-mediated immune responses to Eikenella corrodens (a bacterium that causes periodontal lesions in gnotobiotic rats) was measured and compared with the rate of appearance of macroscopic lesions. A possible inverse relationship was found. A strong cell-mediated immune response, as measured by skin reactivity and lymphocyte mitogenesis, occurred between 4 and 6 weeks after infection and subsided soon thereafter to a low response level. Humoral antibodies to endotoxin from E. corrodens could not be detected at any time. The disease developed only after the cell-mediated immune response diminished, thus suggesting that lack of an efficient immune response may permit the development of the disease. This is seemingly in contradiction to the assumption that tissue destruction in such cases is caused by the immune response and its products. We are inclined to believe, based on our findings reported here, that the lack of immune responsiveness to the bacterium and/or its products is the major causative factor in the development of periodontitis. At the same time, we wish to emphasize that occurrence of both phenomena during the long development of periodontal disease is possible.     

Cell-free translation of avian erythroblastosis virus RNA yields two specific and distinct proteins with molecular weights of 75,000 and 40,000

Avian erythroblastosis virus (AEV) 28 S virion RNA was translated in vitro in cell-free reticulocyte lysates. Two AEV-specific proteins, one of 75,000 (p75) the other of 40,000 (p40) molecular weight, were detected. p75 is a fusion protein containing gag-specific and AEV-specific peptides. It appears to be translated from the 5′-end of the 28 S AEV RNA and is indistinguishable from the p75 detected in AEV-transformed cells (Hayman et al., 1979). p40 does not share sequences with any viral structural protein. It also contains peptides distinct from those of p75, but one of the five identifiable p40 peptides comigrates with one of the p75 peptides. p40 is translated from a 20 S RNA which contains the 3′-half of the AEV-specific sequences of the genome. These two proteins account for all of the coding capacity of the AEV-specific gene sequences in the 28 S AEV RNA and are candidates for leukemia-specific transforming proteins.     

痢疾杆菌免疫小鼠的GALT中T淋巴细胞亚群的应答状态

以鼠伤寒杆菌Ｇ３０株为对照，应用间接免疫荧光法检测了痢疾杆菌福氏２ａ经口服及腹腔免疫后，小鼠派伊尔氏（ＰＰ）节结、肠系膜淋巴结（ＭＬＮ）及脾脏（ＳＰｔ）中Ｌ３Ｔ４～＋、Ｌｙｔ２～＋Ｔ细胞亚群的变化；并以ＭＴＴ比色法测定了ＣｏｎＡ诱导的淋巴细胞增殖反应。实验发现：无论是口服还是腹腔途径，这两种细菌都诱导出基本相似的Ｔ淋巴细胞反应，即Ｌ３Ｔ４亚群在ＰＰ及ＭＬＮ中均有显著升高，而Ｌｙｔ２亚群均无明显变化；口服途径仅ＰＰ淋巴细胞的增殖反应有明显升高，腹腔途径主要为ＭＬＮ出现淋巴细胞显著的增殖反应。提示：在痢疾菌感染免疫中以Ｌ３Ｔ４亚群起主要作用；ＰＰ作为粘膜免疫的诱导部位；经口途径主要诱导肠道局部淋巴细胞的免疫应答，经腹腔途径虽能诱导多部位免疫应答但有否抗粘膜感染保护作用尚待研究。     

Cloning and expression of the phospholipase C gene from Clostridium perfringens and Clostridium bifermentans.

The phospholipase C gene from Clostridium perfringens was isolated, and its sequence was determined. It was found that the structural gene codes for a protein of 399 amino acid residues. The NH2-terminal residues have the typical features of a signal peptide and are probably cleaved after secretion. Escherichia coli cells harboring the phospholipase C gene-containing plasmid expressed high levels of this protein in the periplasmic space. Phospholipase C purified from E. coli transformants was enzymatically active, hemolytic to erythrocytes, and toxic to animals when injected intravenously. The phospholipase C gene from a related organism, Clostridium bifermentans, was also isolated. The two phospholipase C genes were found to be 64% homologous in coding sequence. The C. bifermentans protein, however, was 50-fold less active enzymatically than the C. perfringens enzyme.     

Heterologous radioimmunossay of monkey alpha-fetoprotein.

Immunoelectrophoresis showed that rabbit anti-human alpha-fetoprotein (AFP) cross-reacts with monkey AFP which was not detectable in the serum from an adult non-pregnant monkey. A heterologous radioimmunoassay of monkey AFP was developed using this antiserum which circumvented the need for purified monkey AFP. The radioimmunoassay is of sufficient sensitivity to measure AFP in maternal and fetal serum and amniotic fluid in the rhesus monkey.     

Effects ofβ 2-adrenergic agonists on isolated guinea pig lung mast cells

The mast cell protective effects of the newly developed long-acting ₂-adrenergic salmeterol and formoterol were compared with those of conventionally used ₂-adrenergic, non-specific -agonists, disodium cromoglycate (DSCG) and theophylline. With the exception of DSCG, all the test agents inhibited ovalbumin-induced histamine release from enzymically dispersed guinea pig lung mast cells in a dose-dependent fashion. At the maximum concentration tested, theophylline produced the highest level of protection, inhibiting up to 90% of ovalbumin-induced histamine release whereas DSCG produced only 10% inhibition. The maximum inhibition produced by all the ₂-adrenergic tested was around 45%. While salmeterol was equipotent with salbutamol, formoterol was at least a 100-fold more potent. Hence the present study confirmed the previously reported mast cell stabilizing actions of conventional ₂-adrenergic and extended the observation to the newly developed long-acting analogues.