Visual pigment: G-protein-coupled receptor for light signals

The visual pigment present in photoreceptor cells is a prototypical G-protein-coupled receptor (GPCR) that receives a light signal from the outer environment using a light-absorbing chromophore, 11-cis-retinal. Through cis-trans isomerization of the chromophore, light energy is transduced into chemical free energy, which is in turn utilized for conformational changes in the protein to activate the retinal G-protein. In combination with site-directed mutagenesis, various spectroscopic and biochemical studies identified functional residues responsible for chromophore binding, color regulation, intramolecular signal transduction and G-protein coupling. Extensive studies reveal that these residues are localized into specific domains of visual pigments, suggesting a highly manipulated molecular architecture in visual pigments. In addition to the recent findings on dysfunctional mutations in patients with retinitis pigmentosa or congenital night blindness, the mechanism of intramolecular signal transduction in visual pigments and their evolutionary relationship are discussed. Received 20 July 1998; received after revision 9 September 1998; accepted 23 September 1998     

基于MIC特征提取与BO-CatBoost的航空发动机RUL预测

针对航空发动机传感器监测的退化参数提取困难,易受噪声干扰及发动机剩余使用寿命预测精度不足等问题,利用最大信息系数、贝叶斯优化算法和类别特征梯度提升算法,提出了一种新的发动机剩余使用寿命预测模型。首先,为有效解决特征提取不足的问题,对采集的传感器历史监测特征进行最大信息系数相关性计算,提取出对发动机寿命运行周期影响较大的关键退化特征。其次,为解决剩余使用寿命预测中的梯度偏差及预测偏移问题,使用基于贝叶斯优化的类别特征梯度提升方法对航空发动机进行剩余使用寿命预测。最后,在美国航空航天局提供的商用模块化航空推进系统仿真数据集上进行实验,结果表明所提预测方法的性能较好,验证了该方法的有效性。     

Differences in cardiac myosin light chain LC1 among human, monkey and sheep

The atrial and ventricular myosin light chains of human, monkey and sheep hearts were compared by dodecylsulfate polyacrylamide gel electrophoresis. The atrial light chain 2 and ventricular light chain 2 are similar among these mammals. However, the atrial light chain 1 of monkey has different electrophoretic mobility from those of human and sheep. The monkey ventricular light chain 1 has same mobility as that of sheep but different from that of human.     

Number of glucocorticoid receptors in lymphocytes and their sensitivity to hormone action

The study demonstrated a decreased level of glucocorticoid receptors (GR) in peripheral blood lymphocytes from hypercholesterolemic subjects, and an elevated level in patients with acute myocardial infarction. In the lymphocytes with a high GR number, dexamethasone inhibited [3H]-thymidine and [3H]-acetate incorporation into DNA and cholesterol, respectively, in the same manner as in the control cells. On the other hand, a decreased GR number resulted in a less efficient dexamethasone inhibition of the incorporation of labeled compounds. These data showed that the sensitivity of lymphocytes to glucocorticoids changed only with a decrease of GR level.     

Atomic structure of a fragment of human CD4 containing two immunoglobulin-like domains.

The structure of an N-terminal fragment of CD4 has been determined to 2.4 A resolution. It has two tightly abutting domains connected by a continuous beta strand. Both have the immunoglobulin fold, but domain 2 has a truncated beta barrel and a non-standard disulphide bond. The binding sites for monoclonal antibodies, class II major histocompatibility complex molecules, and human immunodeficiency virus gp120 can be mapped on the molecular surface.     

Effect of recombinant human granulocyte colony-stimulating factor on human neutrophil adherence in vitro.

We measured the effects of recombinant human granulocyte-colony stimulating factor (rhG-CSF) on the adherence of human neutrophils by using a dacron fiber system to assay the adhesive ability of neutrophils. rhG-CSF enhanced neutrophil adherence to dacron fibers. N-formyl-methionyl-leucyl-phenylalanine (fMLP) induced neutrophil-neutrophil interaction (neutrophil aggregation) in addition to neutrophil-dacron interaction, whereas rhG-CSF did not cause neutrophil aggregation. These results indicated that rhG-CSF increases the adhesive ability of neutrophils without neutrophil-neutrophil interaction, and the action of rhG-CSF in neutrophil activation is different from the neutrophil activation caused by fMLP.     

Comparative platelet anti-aggregant activity of D-cysteinolic acid analogues

D-Cysteinolic acid (1) analogues with an S-C-C-N skeleton showed increased platelet anti-aggregant activity in the following order: 2-aminoethanesulfonic acids, thiazolidines, 2-aminoethanethiols and 2-aminoethyl disulfides. Methyl substitutions at the 2-position potentiated the activity. Of these analogues, bis [(R)-2-aminopropyl] disulfide was the most potent inhibitor of platelet aggregation, with about 600-fold the activity of (1).