Mycoplasma infection of cultured cells

Mycoplasma contamination is tough to detect and even more difficult to eradicate. It is best to start over fresh from clean cell stocks, but several elimination options are available.     

Genetic imprinting suggested by maternal heterodisomy in nondeletion Prader-Willi syndrome

Prader-Willi syndrome (PWS) is the most common form of dysmorphic genetic obesity associated with mental retardation. About 60% of cases have a cytological deletion of chromosome 15q11q13 (refs 2, 3). These deletions occur de novo exclusively on the paternal chromosome. By contrast, Angelman syndrome (AS) is a very different clinical disorder and is also associated with deletions of region 15q11q13 (refs 6-8), indistinguishable from those in PWS except that they occur de novo on the maternal chromosome. The parental origin of the affected chromosomes 15 in these disorders could, therefore, be a contributory factor in determining their clinical phenotypes. We have now used cloned DNA markers specific for the 15q11q13 subregion to determine the parental origin of chromosome 15 in PWS individuals not having cytogenetic deletions; these individuals account for almost all of the remaining 40% of PWS cases. Probands in two families displayed maternal uniparental disomy for chromosome 15q11q13. This is the first demonstration that maternal heterodisomy--the presence of two different chromosome 15s derived from the mother--can be associated with a human genetic disease. The absence of a paternal contribution of genes in region 15q11q13, as found in PWS deletion cases, rather than a mutation in a specific gene(s) in this region may result in expression of the clinical phenotype. Thus, we conclude that a gene or genes in region 15q11q13 must be inherited from each parent for normal human development.     

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.     

Baclofen prevents rapid amygdala kindling in adult rats

This study investigates the effect of the gamma-aminobutyric acid (GABA_B) agonist, baclofen, on amygdala kindling in adult rats. Baclofen has been reported to be anticonvulsant in a variety of seizure models and prevents kindling in immature rats. These experiments describe the effects of baclofen (2, 5 and 10 mg/kg, i.p.) on the afterdischarge threshold and kindling rate. Baclofen, 10 mg/kg, significantly increased the afterdischarge threshold in the amygdala. Baclofen at 5 and 10 mg/kg, retarded the rate of kindling as measured by the number of stimuli required to advance to subsequent seizure stages. These results suggest that baclofen may decrease the local excitability of the amygdala and retard the rate of seizure spread (or generalization) throughout the brain. Baclofen, acting at GABA_B receptors exerts an anticonvulsant effect on amygdala kindling in these experiments.     

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.     

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.     

在等离子体条件下用MnO_2对铁液进行含锰还原合金化的研究

还原合金化，即当炼钢或铸造过程需要进行合金化时，不用添加铁合金，而是直接添加所需合金元素的氧化物，通过还原使其合金化。研究结果表明：在等离子体条件下，３０ｍｉｎ内可以达到合锰目标值为１２％～１８％的还原合金化。这一新的冶炼工艺特有可能从根本上改变铁合金的生产现状．     

胺钨盐的性质及其在制取亚微米级钨粉方面的应用

本文着重研究了自还原性胺钨盐的性质及其氢还原,发现,将自还原与一般氢还原适当结合,可以高效率地制备比表面积大于20m~2/g的极细、超细钨粉。对自还原的本性及该类钨盐在制取极细、超细钨粉方面的应用前景进行了讨论。