A possible mechanism of partial twinning in a calf

A two-headed calf had doubled heads and necks, externally normal forelimbs and thorax, incompletely doubled hearts and lungs, and a persistent sinus venosus, with abnormal pulmonary and systemic circulation. Study of the specimen indicated that partial twinning involved the development of the notochord as an anteriorly branched structure, with retention of the single condition posteriorly. It is proposed that anteroposterior compression of the embryonic disk could have induced the formation of double notochords. The way in which compression was produced is suggested.     

血红蛋白氧化生成的自由基对自身红细胞老化作用的初步研究

本文报道用小鼠和家兔做实验,在红细胞悬液(1×10~8细胞/ml)中加入Hb(125×10~(-5)gHb/ml),并在4℃放置4天,溶血百分数为47.8±4.6(%),如果Hb是加入含有甘露醇或SOD的红细胞悬液,则溶血百分数为7.3±6.9和8.0±8.6(两者的P<0.01),红细胞膜脂质过氧化的程度(荧光单位/gHb)也由4.21±0.26分别降至3.61±0.26和3.43±0.17(两者的P<0.01)。家兔溶血前血浆自由基浓度为4.1±1.2,溶血后5分钟和1小时的值分别为14.3±3.6和12.8±1.9(两者的P<0.01)。结果表明,血红蛋白在自动氧化过程中产生自由基,它对自身红细胞产生脂质过氧化和老化作用,并认为在某些溶血性贫血患者体内也存在这种损伤作用。     

A possible role of soluble receptors to cell growth factors in body aging

It is assumed that production by differentiated cells of soluble receptors to cell growth factors may mediate a feedback mechanism controlling cell growth and differentiation in the body. Based on this assumption, it is hypothesized that with age a concentration of such soluble receptors in the body fluids gradually augments as a consequence of increasing a proportion of the differentiated cell pool. In the old body, when present in the cellular microenvironment at relatively high concentrations these receptors might markedly diminish ligand binding to the membrane-bound counterparts in a competitive manner and, thereby, significantly reduce cell regeneration activity. Under such conditions, the niches forming because of cell death could be being filled by connective fibers rather than newly generated cells.     

核纤层蛋白在细胞衰老机制作用中的研究进展

一直以来,对细胞衰老的研究都是细胞生物学和分子生物学研究的重要课题之一,倍受生物学家们的广泛关注,也因此产生了众多的细胞衰老学说,例如:端粒学说、重复基因失活学说、体细胞突变学说、衰老基因学说、代谢废弃物积累学说、大分子交联学说、自由基学说、染色体学说、基因组稳定性学说等.     

Interferon-gamma increases macrophage phospholipid polyunsaturation: a possible mechanism of endotoxin sensitivity.

Incubation of murine macrophages or the macrophage-like cell line P388D with interferon-gamma in vitro induced a significant increase in the polyunsaturated fatty acid content of phosphatidylethanolamine. These increases were time and dose-dependent, being maximal at 12 hours and with 5000 U/ml interferon and were inhibited in the presence of anti-interferon-gamma monoclonal antibody. Interferon-gamma induced a significant increase in linoleate in peritoneal macrophages while in the cell line arachidonate was significantly increased. These results are of interest because such increases in the polyunsaturated fatty acid content of phosphatidylethanolamine were previously shown by us to be associated with increased sensitivity to endotoxin in mice in vivo. The implications for interferon-gamma sensitizing to endotoxin are discussed.     

氯沙坦延缓肾小球系膜细胞衰老及可能机制

目的检测氯沙坦作用衰老系膜细胞后衰老指标及STAT蛋白表达变化,探讨氯沙坦在肾小球系膜细胞衰老过程中的作用及可能机制。方法细胞分三组:对照组、衰老组(10~(-6)molL~(-1)AngⅡ刺激细胞72h)和氯沙坦组(AngⅡ加入前1h加入10~(-5)molL~(-1)氯沙坦,培养72h)。MTT法检测细胞增殖情况,细胞衰老β-半乳糖苷酶(SAβ-gal)染色法检测衰老细胞百分率,流式细胞仪检测细胞周期,倒置显微镜及透射电镜下观察细胞形态及超微结构改变。Western blot检测各组STAT1、p-STAT1、STAT3、p-STAT3蛋白的变化。结果应用氯沙坦后细胞存活率较衰老组明显增加,SAβ-gal阳性率较衰老组明显下降,氯沙坦阻滞于G0-G1期细胞较衰老组明显减少,氯沙坦使肾小球系膜细胞体积增大、多型核、双核等衰老改变的细胞明显减少,细胞核内陷及染色质边集等衰老现象有所改善。衰老细胞内STAT1、p-STAT1、STAT3、p-STAT3表达水平明显增加,应用氯沙坦治疗后STAT1、p-STAT1、STAT3、p-STAT3表达水平均下降,且p-STAT1、p-STAT3下降更明显。结论 JAK2/STAT通路的激活参与了系膜细胞衰老过程,氯沙坦延缓系膜细胞衰老可与下调STAT1、p-STAT1、STAT3及p-STAT3的表达水平相关。     

Role of DJ-1 siRNA in reverse sensitivity of breast cancer cells to chemotherapy and its possible mechanism

Breast cancer which has a high incidence rate is the 2^nd lethal diseases only followed by lung cancer in women. How to improve the recovery rate is the principal problem should be solved in clinical. Previous studies demonstrated the importance of DJ-1 in the existence of breast cancer for the secreted of protein into serum by breast cancer cells both in vitro and in vivo. So the DJ-1 probably could be selected as the target in breast cancer treatment. Adriamycin resistance breast cancer cells MCF-7 and DJ-1 siRNA plasmid were employed to explore the potential clinical application of DJ-1 in this study. Our results showed that the sensitivity of cancer cells to chemotherapeutics was significantly improved with the transfection of DJ-1 siRNA. Further mechanism studies indicated the role of PI3K/AKT/MTOR pathway in the improvement of apoptosis after treatment with adriamycin in DJ-1 silence group.     

Increased dexamethasone sensitivity of neonatal leukocytes: different mechanisms of glucocorticoid inhibition of T cell proliferation in adult and neonatal cells

Glucocorticoids (GC) are known to inhibit the proliferative response of leukocytes after mitogenic activation. Until now, the effects of GC on the immune system have been studied predominantly in adults. However, GC are frequently administered to human fetuses and newborns for the prevention and treatment of respiratory distress syndrome. The immune system of human newborns is still a functionally immature system. Therefore, we wondered whether the immaturity is also reflected by altered responses to hormonal signals such as glucocorticoids. We studied the effects of the GC dexamethasone (DEX) on the proliferation of peripheral blood mononuclear cells and T cells in vitro after stimulation with phytohemagglutinin, anti-CD3, anti-CD3/anti-CD28 or anti-CD2/anti-CD28. Our data demonstrate that neonatal cells are much more sensitive to inhibition of the proliferative response by DEX than adult cells (ED₅₀ 1 ± 0.8 nM vs. 221 ± 135 nM). This difference in sensitivity is not related to differences in affinity and capacity of binding of [³H] DEX. Moreover, we show that the mechanisms of GC inhibition differ between adult and neonatal cells. In adult cells, addition of interleukin (IL)-2 does not restore DEX inhibition of the proliferative response. In contrast, the proliferative response of neonatal cells can be restored completely by the addition of IL-2. These data suggest that the primary target of GC in neonatal cells is inhibition of IL-2 production. In adult cells, other mechanisms are responsible for inhibition of T cell proliferation.     

The accelerated aging phenotype: The role of race and social determinants of health on aging

The pursuit to discover the fundamental biology and mechanisms of aging within the context of the physical and social environment is critical to designing interventions to prevent and treat its complex phenotypes. Aging research is critically linked to understanding health disparities because these inequities shape minority aging, which may proceed on a different trajectory than the overall population. Health disparities are characteristically seen in commonly occurring age-associated diseases such as cardiovascular and cerebrovascular disease as well as diabetes mellitus and cancer. The early appearance and increased severity of age-associated disease among African American and low socioeconomic status (SES) individuals suggests that the factors contributing to the emergence of health disparities may also induce a phenotype of ‘premature aging’ or ‘accelerated aging’ or ‘weathering’. In marginalized and low SES populations with high rates of early onset age-associated disease the interaction of biologic, psychosocial, socioeconomic and environmental factors may result in a phenotype of accelerated aging biologically similar to premature aging syndromes with increased susceptibility to oxidative stress, premature accumulation of oxidative DNA damage, defects in DNA repair and higher levels of biomarkers of oxidative stress and inflammation. Health disparities, therefore, may be the end product of this complex interaction in populations at high risk. This review will examine the factors that drive both health disparities and the accelerated aging phenotype that ultimately contributes to premature mortality.     

Defective high-density lipoprotein composition in patients on chronic hemodialysis. A possible mechanism for accelerated atherosclerosis.

We determined serum high-density lipoprotein cholesterol content and analyzed the approtein structure of the various lipoprotein fractions in 21 patients on chronic hemodialysis. High-density lipoprotein cholesterol was significantly reduced in all patients as compared with 11 normal persons (mean +/-1 standard deviation: 26 +/- 13 vs. 52 +/- 9 mg per 100 ml; P less than 0.001) whether or not triglyceride levels were raised. In seven of those with Type IV hyperlipoproteinemia, protein content of high-density lipoprotein and its subfractions 1, 2 and 3 were also reduced (P less than 0.001) in parallel with reductions in cholesterol in these fractions. Apoprotein electrophoresis showed an increase in "arginine-rich" peptide in very-low-density lipoprotein and high-density lipoprotein fraction 1, and a reduction in apoprotein Cll in very-low-density and high-density lipoprotein. In addition to their reduced high-density lipoprotein cholesterol levels, a major factor in the atherosclerosis of these patients may be their abnormal high-density lipoprotein composition. Their raised triglyceride levels could be due to defective lipoprotein lipase activation by the reduced very-low-density lipoprotein apoprotein.     

Inhibition of host cell catalase by Mycoplasma pneumoniae: a possible mechanism for cell injury.

This study demonstrates that viable Mycoplasma pneumoniae cells inhibit catalase activity in several types of intact human cells as well as in solution. Human erythrocyte catalase was inhibited up to 72%, and the inhibition of catalase in human cultured skin fibroblasts, lung carcinoma epithelial cells, and ciliated epithelial cells from human nasal polyps ranged between 75 and 80%. UV light-killed mycoplasmas failed to inhibit catalase activity both in intact cells and in vitro. After M. pneumoniae infection of human cultured skin fibroblasts, the level of malonyldialdehyde, an indicator for membrane lipid peroxidation, was 3.5 times higher than in control fibroblasts. Virulent M. pneumoniae completely inhibited catalase activity in solution, whereas the nonvirulent strains had a lesser ability to inhibit catalase activity. These findings suggest that as a result of host cell catalase inhibition by M. pneumoniae, the toxicity of the hydrogen peroxide generated by the microorganism and the affected cell is enhanced, thereby inducing host cell damage.     

A study on creatine uptake into human erythrocytes: relation to erythrocyte aging]

In order to assess the relation between creatine uptake into human erythrocytes and erythrocyte aging, actual influx of creatine into erythrocytes and creatine contents in erythrocytes were measured by using method of high performance liquid chromatography and isotopic estimation of 14C-creatine concentration. Actual influx of creatine into erythrocytes was showed rapidly, in spite of constant contents of erythrocyte creatine under the condition to be incubated at 37 degrees C for approximate 4 hours in isotonic saline containing high concentration of creatine. Km values of the creatine uptake into young erythrocytes were evidently smaller than that into old erythrocytes. On the other hand, no significant difference of Vmax values was observed to be dependent on erythrocyte aging.     

In vitro cytotoxicity of maxillofacial silicone elastomers: effect of accelerated aging

The purpose of this in vitro study was to evaluate the cytotoxicity of three maxillofacial silicone elastomers at 24, 48, and 72 h on L-929 cells and to determine the effect of accelerated aging on the cytotoxicity of these silicone elastomers. Disc-shaped test samples of maxillofacial silicone elastomers (Cosmesil, Episil, Multisil) were fabricated according to manufacturers' instructions under aseptic conditions. Samples were then divided into three groups: (1) not aged; (2) aged for 150 h with an accelerated weathering tester; and (3) aged for 300 h. Then the samples were placed in Dulbecco's Modified Eagle Medium/Ham's F12 (DMEM/F12) for 24, 48, and 72 h. After the incubation periods, cytotoxicity of the extracts to cultured fibroblasts (L-929) was measured by MTT assay. The degree of cytotoxicity of each sample was determined according to the reference value represented by the cells with a control (culture without sample). Statistical significance was determined by repeated measurement ANOVA (p < 0.01) followed by Duncan's test (p < 0.05). All test materials in each group demonstrated high survival rates in MTT assay (Episil; 93.84%, Multisil; 88.30%, Cosmesil; 87.50%, respectively); however, in all groups, Episil material demonstrated significantly higher cell survival rate after each of the experimental incubation periods (p < 0.05). Accelerated aging for 150 and 300 h had no significant effect on the biocompatibility of maxillofacial silicone elastomers tested (p > 0.05).     

Senescent erythrocytes: factors affecting the aging of red blood cells

Human red blood cells (RBC) have a well-defined lifespan of 120 days affected by many cellular parameters. The aim of the present study was to investigate through a functional assay the effect of some factors in the interaction of erythrocytes with monocytes: heat rigidification, equilibration at different pH and desialyzation. We also studied the interaction between stored RBC and peripheral blood monocytes with this functional erythrophagocytosis assay. Blood samples from 30 volunteer donors were investigated. 1) Senescent (Se) and Young (Y) RBC were obtained by differential centrifugation. 2) Erythrocyte suspensions: Aliquots of each sample were subjected to the following treatments: a) Rigidification by heat (RRBC), b) Equilibration at different pH (5.34, 6.30, 7.33, 9.20) and c) Desialyzation with neuraminidase and trypsin. The functional assay was performed incubating monocytes obtained by glass adherence with these suspensions of RBC. Whole blood samples (n = 20) were stored during different periods of time (0, 7, 14, 21, 28, 35 and 42 days). The erythrophagocytosis assay was performed during six weeks incubating isologous monocytes with RBC from every unit. Negative and positive controls were performed using non sensitized (NSRBC) and sensitized with IgG anti-RhD (SRBC) red cells. The percentage of active monocytes (AM) obtained were: 1) YRBC: 2.8 +/- 0.9 and SeRBC: 17.5 +/- 2.1; 2a) RRBC: 3.0 +/- 0.9; 2b) 10.9 +/- 0.9, 15.5 +/- 0.8, 3.1 +/- 1.0, 4.0 +/- 1.1; 2c) 11.1 +/- 1.4 and 3.9 +/- 1.0; SRBC 32.1 +/- 1.7 and NSRBC: 2.8 +/- 1.5. The % of AM with SeRBC was higher (p < 0.001) than those obtained with NSRBC. The data of AM with RRBC were significantly lower (p < 0.001) than those obtained with SeRBC and SBRC, indicatingthat heat rigidification of RBC does not increase phagocytosis by monocytes. The values of AM obtained from the suspensions of erythrocytes equilibrated at different pH indicate that the acidification of RBC increases the interaction with monocytes. The % AM with neuraminidase treated RBC was higher than those observed with YRBC and NSRBC (p < 0.001). No modifications were observed with trypsin treated RBC. These results suggest that the loss of sialic acid may be involved in the physiological phagocytosis. The values of AM of stored whole blood were: 2.3 +/- 1.3, 2.7 +/- 1.3, 4.4 +/- 1.6, 6.7 +/- 1.2, 9.6 +/- 1.0, 11.7 +/- 0.8 and 13.0 +/- 1.2. The results showed a significant increase in the % of AM as a function of the preservation time from 2,3 +/- 1,3 for the first day to 13,0 +/- 1,2 for the 42nd day (p < 0.001). The data obtained in this ex vivo model show a significant increase (p<0.001) in the phagocytosis of RBC equilibrated at low pH, desialinized (greater than 80%) with neuraminidase and stored for over 28 days. These factors would be involved in erythrocyte removal via phagocytosis during tissular homeostasis.     

The sensitivity of adrenal responses to synthetic adrenocorticotrophin in the conscious unrestrained calf.

1. Changes in cortisol and corticosterone output and blood flow from the adrenal gland have been determined in the conscious unrestrained calf during I.V. infusions of synthetic adrenocorticotrophin (Synacthen) at 0-5 ng-kg(-1) min- minus 1 (low dose), 5 ng-kg- minus 1 (medium dose), 50 ng-kg- minus 1 min- minus 1 (high dose) and 500 ng-kg- minus 1 min- minus 1 (medium dose), 50 ng-kg- minus 1 min- minus 1 (high dose) and 500 ng-kg- minus 1 min- minus 1(very high dose). 2. Infusions at the low dose produced a rise in adrenal output of both cortisol and corticosterone to maximum values of approximately 100 and 30 ng-kg- minus 1 min- minus 1 respectively. Mean output of both steroids was significantly increased within 5 min, reached a maximum within 10 min and had fallen to resting levels 10 min after the infusion was discontinued. 3. The effects of infusions at both the high and very high doses were closely similar; maximal cortisol outputs were within the range 600-800 ng-kg- minus 1 min- minus 1 and corticosterone 350-500 ng-kg- minus 1 min- minus 1 in both groups. 4. When the infusions were terminated, pronounced differences were observed in the rates at which steroid outputs declined. Basal levels were restored within 10 min following the low dose and within 60 min in medium dose animals, but both cortisol and corticosterone output were still elevated 2 hr after infusion in high dose animals. In calves infused at the very high dose, cortisol output did not fall significantly during 2 hr period. The ratio of cortisol: corticosterone released from the adrenal gland immediately before infusion (3-2 +/- 0-3) approximated to the proportions in which the two steroids were found in the arterial plasma, but fell progressively to a minimum (1-3 +/- 0-1) with increasing doses of Synacthen. Conversely, the ratio of the steroids in the arterial plasma was increased during infusions at the low dose, but not at the higher doses. 6. No significant change in adrenal blood flow occurred during Synacthen infusion in low dose animals despite the increase in steroid output. In medium dose animals blood flow through the gland rose during infusion by approximately 75 per cent while in both high and very high dose animals the flow increased by up to 300 percent. 7. In the three groups in which adrenal hyperaemia occurred, blood flow had fallen to within the resting range 45 min after infusion: in each case this fall was much more rapid than the fall in steroid output. No significant increase in aortic blood pressure or heart rate accompanied infusion of Synacthen, indicating that adrenal hyperaemia was dependent upon vasodilatation with the gland. 8. Administration of cycloheximide (10 mg/kg) by I.V. injection either before or during an infusion of Synacthen, inhibited steroidogenesis without affecting the vasodilator response.     

Altered cord blood gammadelta T cell repertoire in Nigeria: possible impacts of environmental factors on neonatal immunity

Infectious diseases during pregnancy can impact the development of fetal immunity, leading to reduced neonatal resistance to infection and decreased responses to pediatric vaccines. Plasmodium falciparum causes placental infection in low parity pregnant women and is among the pathogens that affect fetal immunity. Recognizing the relationship between malaria and gammadelta T lymphocytes in adults, we asked whether neonatal gammadelta T cells would be altered in malaria-endemic regions as a marker for changes in fetal immunity. Our initial studies compared cord blood gammadelta T cells from deliveries to HIV- mothers in Jos (Nigeria) where malaria is endemic, or in Rome (Italy). We noted substantial differences in the Vgamma2 repertoire for cord blood collected in Jos or Rome; differences were consistent with a negative selection mechanism operating on the fetal Vgamma2 chain repertoire in neonates from Jos. A specific disruption affected the fraction of gammadelta T cells that we expect will respond to Bacille Calmette-Guerin (BCG). Fetal gammadelta T cell depletion might be a mechanism for impaired neonatal immunity and lowered responses to pediatric vaccines.     

Priming of microglia in a DNA-repair deficient model of accelerated aging

Aging is associated with reduced function, degenerative changes, and increased neuroinflammation of the central nervous system (CNS). Increasing evidence suggests that changes in microglia cells contribute to the age-related deterioration of the CNS. The most prominent age-related change of microglia is enhanced sensitivity to inflammatory stimuli, referred to as priming. It is unclear if priming is due to intrinsic microglia ageing or induced by the ageing neural environment. We have studied this in Ercc1 mutant mice, a DNA repair-deficient mouse model that displays features of accelerated aging in multiple tissues including the CNS. In Ercc1 mutant mice, microglia showed hallmark features of priming such as an exaggerated response to peripheral lipopolysaccharide exposure in terms of cytokine expression and phagocytosis. Specific targeting of the Ercc1 deletion to forebrain neurons resulted in a progressive priming response in microglia exemplified by phenotypic alterations. Summarizing, these data show that neuronal genotoxic stress is sufficient to switch microglia from a resting to a primed state.     

Racial differences in plasma high-density lipoproteins in patients receiving hemodialysis. A possible mechanism for accelerated atherosclerosis in white men

Among 346 nondiabetic patients receiving long-term hemodialysis, cardiovascular mortality was higher in white than in black men (P less than 0.02) but was similar between black and white women, despite the higher incidence of nephrosclerosis in black men and women (59 and 58 per cent vs. 8 and 10 per cent, respectively; P less than 0.0001). There were significant racial differences in plasma lipid and apoprotein levels in a subset of 100 of these patients. The white men had higher levels of plasma triglyceride and lower levels of high-density-lipoprotein (HDL) cholesterol, apoprotein A-I, and apoprotein A-II than black men; concentrations of HDL, apoprotein A-I, and apoprotein A-II were also lower in white than in black women. The distribution of the HDL subfractions HDL2, HDL3, and HDL3D, as determined by zonal ultracentrifugation, was normal in black and abnormal in white men receiving hemodialysis. HDL2 concentrations were higher in black than in white men by both zonal analysis (P less than 0.05) and polyanionic precipitation of the HDL subfractions (P less than 0.01). The distributions and concentrations of HDL2 and HDL3L were similar in black and white women. Thus, there are marked racial differences in HDL in male patients receiving hemodialysis. The abnormalities in HDL and the hypertriglyceridemia in the white men may explain their high rate of cardiovascular mortality.