The search for a marsupial XIC reveals a break with vertebrate synteny

X-chromosome inactivation (XCI) evolved in mammals to deal with X-chromosome dosage imbalance between the XX female and the XY male. In eutherian mammals, random XCI of the soma requires a master regulatory locus known as the ‘X-inactivation center’ (XIC/Xic), wherein lies the noncoding XIST/Xist silencer RNA and its regulatory antisense Tsix gene. By contrast, marsupial XCI is imprinted to occur on the paternal X chromosome. To determine whether marsupials and eutherians share the XIC-driven mechanism, we search for the sequence equivalents in the genome of the South American opossum, Monodelphis domestica. Positional cloning and bioinformatic analysis reveal several interesting findings. First, protein-coding genes that flank the eutherian XIC are well-conserved in M. domestica, as well as in chicken, frog, and pufferfish. However, in M. domestica we fail to identify any recognizable XIST or TSIX equivalents. Moreover, cytogenetic mapping shows a surprising break in synteny with eutherian mammals and other vertebrates. Therefore, during the evolution of the marsupial X chromosome, one or more rearrangements broke up an otherwise evolutionarily conserved block of vertebrate genes. The failure to find XIST/TSIX in M. domestica may suggest that the ancestral XIC is too divergent to allow for detection by current methods. Alternatively, the XIC may have arisen relatively late in mammalian evolution, possibly in eutherians with the emergence of random XCI. The latter argues that marsupial XCI does not require XIST and opens the search for alternative mechanisms of dosage compensation.     

The innate immune response under the control of the LXR pathway

Macrophages play essential roles in infection and resolution of inflammation. This review summarizes recent findings that suggest a relevant role for the nuclear receptor liver X receptor (LXR) in the evolution of immune responses. By exerting both positive and negative regulation of specific macrophage gene expression networks, LXRs display anti-inflammatory activities and promote macrophage survival in bacterial infection settings. Agonists that activate the LXR pathway may be used to enhance innate immunity to highly virulent pathogens that otherwise induce macrophage apoptosis as a means to subvert host immune defense.     

结核性脑膜炎的CT诊断(附16例分析)

目的：通过分析16例结核性脑膜炎的CT表现及其产生的病理基础，提高对本病的认识和诊断水平。方法：16例结核性脑膜炎病人采用常规头颅CT扫描，对其影像及临床资料进行回顾性分析。结果：脑基底池、侧裂池变窄12例(75％)，合并密度增高8例(50％)；不同程度的脑积水14例(88％)；脑梗塞8例(50％)；结核瘤1例(6％)。结论：结核性脑膜炎的主要CT征象是脑基底池、侧裂池变窄，同时有不同程度的脑积水。如同时伴有脑结核瘤，可作出诊断。     

Behavioral characteristics of rat lines selected for differential hypothermic responses to cholinergic or serotonergic agonists

The present review will describe the formation of two pharmacologically selected lines of rats, their behavioral phenotypes, their responses to select drugs, their possible neurochemical correlates, and their use to detect the therapeutic potential of antidepressant drugs. The Flinders Line rats were established at Flinders University in Australia by selectively breeding for differential responses to an anticholinesterase agent from outbred Sprague-Dawley (SD) rats; the Flinders Sensitive Line (FSL) rats were more sensitive to the hypothermic and behavioral suppressing effects of this agent than the Flinders Resistant Line (FRL) rats. The 8-OH-DPAT line rats were established at the University of North Carolina at Chapel Hill by selectively breeding for differential hypothermic responses to the 5-HT_1A receptor agonist, 8-OH-DPAT; the high DPAT sensitive (HDS) line rats were more sensitive to the hypothermic effects of 8-OH-DPAT than the low DPAT sensitive (LDS) line rats. Studies of these two pairs of lines have indicated that the FSL and HDS rats are both more susceptible to stress-induced behavioral disturbances. Their usefulness in detecting potential antidepressant drugs and the relationship between mood disorders and drug abuse will be discussed.     

环孢素A体外诱导HL—60细胞凋亡的研究

目的：观察环孢素Ａ是否有诱导白血病细胞凋亡的作用。方法：应用细胞形态学检查、二苯胺法ＤＮＡ片段化定量，ＤＮＡ凝胶电泳及流式细胞术等方法观察细胞凋亡。结果：ＣｓＡ５０ｍｇ／Ｌ作用ＨＬ－６０细胞４ｈ，ＤＮＡ片段率显著增高，达（２８．２±５．８）％，而对照组仅为（１２．５±１．７）％（Ｐ＜０．０１，ｎ＝１０）。光镜及电镜检查见细胞核固缩，碎裂，有凋亡小体形成。ＤＮＡ电泳显示典型的ＤＮＡｌａｄｄｅｒ。流式细胞术检测发现ＣｓＡ５０ｍｇ／Ｌ作用ＨＬ－６０细胞６ｈ凋亡细胞率为４９．７％，而空白组仅为９．１％。ＣｓＡ诱导ＨＬ－６０细胞ＤＮＡ片段化呈剂量和时间依赖性。结论：ＣｓＡ在体外能诱导ＨＬ－６０细胞凋亡。     

H-Y antigen expression in patients with X-autosomal translocations and gonadal dysgenesis

Cells from three patients with early gonadal failure and a balanced reciprocal translocation involving the long arm of the X chromosome and an autosome were studied. Fibroblasts from a patient with a similar balanced reciprocal translocation but normal reproductive capabilities were also studied. Two of the four patients were found to have serologically detectable H-Y antigen on their cells. Since H-Y antigen has been found on the cells of other patients with X chromosome abnormalities but without a Y chromosome, it is thought that the X chromosome plays a role in the regulation of H-Y antigen expression. This study suggests that the long arm of the X chromosome may be involved but the location of a regulatory gene cannot be identified in these studies. These cases do not permit us to implicate H-Y antigen as a cause of gonadal dysgenesis and early gonadal failure in females who have structurally abnormal X chromosomes.     

An Epstein-Barr virus-producer line Akata: Establishment of the cell line and analysis of viral DNA

An Epstein-Barr virus (EBV)-producer line, designated Akata, was established from a Japanese patient with Burkitt's lymphoma. The Akata line possessed the Burkitt's-type chromosome translocation, t(8q-; 14q+), and was derived from the tumor cell. Akata cells produced a large quantity of transforming virus upon treatment of cells with anti-immunoglobulin antibodies (Takada, 1984). Southern blot analysis of viral DNA indicated that the Akata EBV is nondefective and more representative of wild-type viruses. Akata cells should be useful as a source of EBV.     

Is there an effect of monocular deprivation on the proportions of X and Y cells in the cat lateral geniculate nucleus?

Summary The proportions and receptive field properties of X and Y cells in the A and A1 layers of the lateral geniculate nucleus (LGN) were studied in monocularly deprived cats. Contrary to previous reports, we found that there was no change in the relative number of Y cells in the geniculate layers driven by the deprived eye. There was also no marked change in the spatial resolution of X or Y cells driven from the deprived eye as compared to the cells driven from the normally experienced eye. In these same cats, the visual evoked potential from stimulation of the deprived eye with grating patterns was markedly reduced in amplitude. Furthermore, the cell bodies of the cells in the LGN driven by the deprived eye had shrunk. Therefore, these usual consequences of monocular deprivation are not necessarily associated with a loss of geniculate Y cells.     

Cardiovascular indices of physiological arousal in boys with fragile X syndrome

In this study, the relationship between physiological arousal, as indexed by heart rate variability, was examined in boys with fragile X syndrome (FXS) and typically developing boys matched on chronological age. In addition, the relationship of heart activity to clinical and molecular factors in the group of boys with FXS was examined. Results suggest that boys with FXS have higher levels of heart activity during the passive phases, as reflected in shorter heart periods. This high level of heart activity appears to be due to increased sympathetic activity and reduced parasympathetic activity. Boys with FXS did not display the expected patterns of heart activity in response to phases of increasing challenge, and sympathetic and parasympathetic systems did not appear coordinated in these boys with FXS. Clinical factors may be related to neural regulation of heart activity while molecular factors do not appear to be.