Functional cloning of ICAM-2, a cell adhesion ligand for LFA-1 homologous to ICAM-1

The leukocyte adhesion molecule LFA-1 mediates a wide range of lymphocyte, monocyte, natural killer cell, and granulocyte interactions with other cells in immunity and inflammation. LFA-1 (CD11a/CD18) is a receptor for intercellular adhesion molecule 1 (ICAM-1, CD54), a surface molecule which is constitutively expressed on some tissues and induced on other in inflammation. Induction of ICAM-1 on epithelial cells, endothelial cells and fibroblasts mediates LFA-1-dependent adhesion of lymphocytes. Several lines of evidence have suggested the existence of a second LFA-1 ligand: homotypic adhesion of one cell line was inhibited by a monoclonal antibody to LFA-1, but not by one to ICAM-1; there exists an LFA-1-dependent, ICAM-1-independent pathway of adhesion to endothelial cells; and also, there are some types of target cells in which LFA-1-dependent T-lymphocyte adhesion and lysis are independent of ICAM-1. We have cloned this second ligand, designated ICAM-2, using a novel method for identifying ligands of adhesion molecules. ICAM-2 is an integral membrane protein with two immunoglobulin-like domains, whereas ICAM-1 has five. Remarkably, ICAM-2 is much more closely related to the two most N-terminal domains of ICAM-1 (34% identity) than either ICAM-1 or ICAM-2 is to other members of the immunoglobulin superfamily, demonstrating the existence of a subfamily of immunoglobulin-like ligands that bind the same integrin receptor.     

电刺激肌力控制的新技术

利用宽范围内变化的运动单位动作电位发放率和募集控制模式来调节骨骼肌的收缩力,克服了神经肌肉电刺激技术中一个长期存在的障碍。对于猫的腓肠肌,控制模式中运动单位的募集可以控制初始肌力的50%直至100%。对应于线性增加的募集,肌力响应也是线性的,而对应于发放率,肌力出现非线性饱和段。     

Abnormalities of meioses in male reciprocal hybrids between the Hiroshima and Ichinoseki populations ofRana japonica

In order to elucidate cytogenetically the cause of male sterility in intraspecific hybrids ofRana japonica, the behavior of chromosomes in the first meiosis was observed in spermatocytes from male reciprocal hybrids between two populations from Hiroshima and Ichinoseki. In the parental Hiroshima and Ichioseki populations, 2530 (96.7%) meiotic spreads had 13 bivalents and 78 (3.0%) contained 12 bivalents and two univalents, whereas in reciprocal hybrids only 337 (7.0%) contained 13 bivalents and the other 4445 (93.0%) had 2–26 univalents. A total of 31647 (93.4%) bivalents was ring-shaped and the other 2234 (6.6%) were rod-shaped in both parental populations, whereas in reciprocal hybrids 26352 (57.1%) and 19819 (42.9%) bivalents were ring- and rod-shaped, respectively. These results show that meiotic chromosomes of reciprocal hybrids are characterized by a remarkable increase in univalents and rod-shaped bivalents.     

Protective effect of Shigyaku-to,a traditional Chinese herbal medicine,on the infection of herpes simplex virus type 1 (HSV-1) in mice

The antiviral activity of Shigyaku-to (TJS-109), a traditional Chinese herbal medicine, was investigated in mice infected with herpes simplex virus type 1 (HSV-1). TJS-109 is a combination of the medicinal plant extracts fromZingiberis siccatum rhizoma,Aconiti tuber andGlycyrrhizae radix in a specific proportion. Mice infected with a 10 LD₅₀ dose of HSV-1 were treated with TJS-109 orally at doses of 1.25 to 20 mg/kg 2 days before, and 1 and 4 days after the infection. The treated groups had 80% (1.25 mg/kg), 40% (5 mg/kg) and 23% (20 mg/kg) mortality rates 25 days after the infection as compared with a 100% mortality rate in control mice treated with saline. When HSV-1 infected mice (recipients) received CD8⁺T cell fractions derived from spleens of mice treated with TJS-109 (donors), 70% of recipients survived, as compared with 0% survivors in the groups of mice treated with saline, B cell fractions, CD4⁺ T cell fractions or macrophage-enriched fractions prepared from the same donors. TJS-109 did not show any virucidal activities against HSV-1 or any virostatic activities on the growth of HSV-1 in Vero cells. These results suggest that TJS-109 protected mice exposed to lethal amounts of HSV-1 through the activation of CD8⁺ T cells.     

A morphometric study of spermatogenesis in the testes of mice of a senescence accelerated strain

The morphometric parameters of spermatogenic cells in a mouse strain prone to accelerated senescence (SAM-P), a novel murine model of spontaneously promoted aging, were compared with those of a SAM resistant strain (SAM-R) after birth until 40 weeks (mean life span of SAM-P). A mixture of gonocytes and spermatogonia were present in the testis in 1-week-old mice, and no gonocytes were observed in 2-week-old mice. At 6 weeks of age, the absolute number of spermatogonia in SAM-P was 27% greater than that in SAM-R, whereas the cell number in 40-week-old SAM-P was 17% less than in SAM-R. Primary spermatocytes were first observed in 3-week-old animals, and the cell numbers in SAM-P at 3, 5 and 6 weeks were 78%, 31% and 25%, respectively, greater than in SAM-R, whereas the cell number in SAM-P at 40 weeks was 30% less than SAM-R. Round spermatids were first observed in all SAM-P at 4 weeks old, but 20% of SAM-r had no spermatids and the rest had only a few. At 5 and 6 weeks old, the absolute numbers of round spermatids in SAM-P was about 34% and 41%, respectively, greater than in SAM-R, whereas the cell number in 40-week-old SAM-P was about 34% less than SAM-R. These results indicate that testicular maturation begins at an earlier age in SAM-P than SAM-R. Furthermore, at the age of 40 weeks signs of testicular deterioration are evident in SAM-P mice only     

Inhibition of glucose transport in human erythrocytes by 2,3-dioxoindole (Isatin)

10 mM isatin (2,3-dioxoindole) inhibited glucose influx into human erythrocytes by over 30%. The inhibition is of the competitive type, where the affinity constant (K_t) was increased from 5.71 (control) to 11.11 mM in the presence of isatin with no change in V_max (130 nmol/min/ml packed cells). The observed inhibition of sugar transport by isatin was not mediated through membrane–SH groups accessible to iodoacetate, iodoacetamide, DTNB, DNP or sodium arsenite. Isatin inhibited sugar transport in the presence of 2 mM harmaline, an alkaloid inhibitor of Na⁺, K⁺–ATP_ase activity. The inhibition was non additive which suggests that these two compounds interact with the same or a similar site on the erythrocyte membrane.     

石棉对N，N－二甲基苯胺的吸附和氧化作用

研究了青石棉、温石棉、直闪石和铁石棉与不同浓度Ｎ，Ｎ－二甲基苯胺（ＤＭＡ）在１１０℃的吸附氧化反应，测定了产物的紫外可见光谱、红外光谱、元素分析和热分析数据．结果表明，四种石棉均能使ＤＭＡ氧化为甲基紫．质子可以提高石棉的氧化能力．此外，反应过程还生成一种紫外可见光最大吸收为３４０ｎｍ的物质，其结构有待进一步鉴定．     

A binding site for the T-cell co-receptor CD8 on the alpha 3 domain of HLA-A2

Adhesion measurements between CD8 and 48 point mutants of HLA-A2.1 show that the CD8 alpha-chain binds to the alpha 3 domain of HLA-A2.1. Three clusters of alpha 3 residues contribute to the binding, with an exposed, negatively charged loop (residues 223-229) playing a dominant role. CD8 binding correlates with cytotoxic T-cell recognition and sensitivity to inhibition by anti-CD8 antibodies. Impaired alloreactive T-cell recognition of an HLA-A2.1 mutant with reduced affinity for CD8 is not restored by functional CD8 binding sites on an antigenically irrelevant class I molecule. Therefore, complexes of CD8 and the T-cell receptor bound to the same class I major histocompatibility complex molecule seem to be necessary for T-cell activation.