Identity of differentiation inducing factor and tumour necrosis factor

Human myelogenous leukaemic cells can be induced to differentiate into the monocyte/macrophage pathway by protein inducers called differentiation inducing factors (DIF) in conditioned media of mitogen-stimulated human peripheral blood leukocytes. However, human DIF has not yet been well characterized. DIF is known to be a T-cell lymphokine, as it can be obtained from the T-cell line HUT-102 and can be partially purified from medium conditioned by phytohaemagglutinin (PHA)-stimulated lymphocytes. We found that monocytes also produce factor(s) that induce differentiation of human myelogenous leukaemia cell lines to cells with macrophage-like characteristics. This factor(s) has activity different from that of colony-stimulating factor(s) or interferons. We have now purified a DIF to homogeneity from medium conditioned by PHA-stimulated leukocytes using a human myeloblastic leukemia cell line, ML-1, as target cells. The purified DIF has a relative molecular mass (Mr) of approximately 17,000, with an NH2-terminal sequence the same as that of human tumour necrosis factor (TNF). Recombinant human TNF (rHuTNF) induces differentiation of ML-1 cells and an anti-pDIF monoclonal antibody can neutralize both differentiation inducing activity and cytotoxic activity of DIF and rHuTNF. The findings indicate that one of the DIF(s) produced by leukocytes is probably TNF.     

Apoptosis occurs in granulosa cells but not cumulus cells in the atretic antral follicles in pig ovaries

The porcine antral follicles, 3–6 mm in diameter, were dissected from the ovaries of mature pigs, and then granulosa and cumulus cells were isolated from each follicle. In atretic follicles, high activity of neutral Ca²⁺/Mg²⁺-dependent endonuclease and DNA ladder formation, estimated by electrophoresis, were noted in granulosa cells but not in cumulus cells. Extremely low activity of the endonuclease and no DNA ladder formation were observed in both types of cells obtained from healthy follicles. Moreover, apoptotic cells were observed histochemically among granulosa cells only. A good correlation (r=0.987) between the endonuclease activity of granulosa cells and the progesterone/estradiol ratio of follicular fluid in each follicle was found. These results suggest that apoptosis occurs in granulosa cells but not cumulus cells in the atretic antral follicles in pigs.     

S-phase checkpoint proteins Tof1 and Mrc1 form a stable replication-pausing complex

The checkpoint regulatory mechanism has an important role in maintaining the integrity of the genome. This is particularly important in S phase of the cell cycle, when genomic DNA is most susceptible to various environmental hazards. When chemical agents damage DNA, activation of checkpoint signalling pathways results in a temporary cessation of DNA replication. A replication-pausing complex is believed to be created at the arrested forks to activate further checkpoint cascades, leading to repair of the damaged DNA. Thus, checkpoint factors are thought to act not only to arrest replication but also to maintain a stable replication complex at replication forks. However, the molecular mechanism coupling checkpoint regulation and replication arrest is unknown. Here we demonstrate that the checkpoint regulatory proteins Tof1 and Mrc1 interact directly with the DNA replication machinery in Saccharomyces cerevisiae. When hydroxyurea blocks chromosomal replication, this assembly forms a stable pausing structure that serves to anchor subsequent DNA repair events.     

Role of adenosine A1 and A2 receptors in the regulation of aldosterone production in rat adrenal glands

Summary To investigate the roles of adenosine A₁ and A₂ receptors in the regulation of aldosterone production, we examined the effects of adenosine and adenosine agonists (N⁶-cyclohexyl adenosine; selective adenosine A₁ receptor agonist and 5-N-ethylcarboxamine adenosine; selective adenosine A₂ receptor agonist) on aldosterone and cyclic AMP production in rat adrenal capsular cells. Neither adenosine nor 5-N-ethylcarboxamine adenosine caused significant effects on basal aldosterone or cyclic AMP production. Also, adenosine (10^–3M) showed no consistent effects on aldosterone and cyclic AMP production induced by ACTH. On the other hand, N⁶-cyclohexyl adenosine exhibited a significant inhibition of basal aldosterone and cyclic AMP production at doses of 10^–4 M and 10^–3 M; furthermore, 10^–3 M N⁶-cyclohexyl adenosine inhibited aldosterone and cyclic AMP production stimulated by ACTH. These results suggest that adenosine A₁ receptors are coupled to and inhibit adenylate cyclase and may be involved in the inhibition of aldosterone production.     

岩石蠕变及疲劳破坏过程和破坏极限研究

介绍了蠕变试验及疲劳试验与岩石破坏过程和普通的单轴压缩破坏过程之间相关性以及岩石的蠕变极限和疲劳极限的研究结果。     

Deficiency in catechol-O-methyltransferase and 2-methoxyoestradiol is associated with pre-eclampsia

Despite intense investigation, mechanisms that facilitate the emergence of the pre-eclampsia phenotype in women are still unknown. Placental hypoxia, hypertension, proteinuria and oedema are the principal clinical features of this disease. It is speculated that hypoxia-driven disruption of the angiogenic balance involving vascular endothelial growth factor (VEGF)/placenta-derived growth factor (PLGF) and soluble Fms-like tyrosine kinase-1 (sFLT-1, the soluble form of VEGF receptor 1) might contribute to some of the maternal symptoms of pre-eclampsia. However, pre-eclampsia does not develop in all women with high sFLT-1 or low PLGF levels, and it also occurs in some women with low sFLT-1 and high PLGF levels. Moreover, recent experiments strongly suggest that several soluble factors affecting the vasculature are probably elevated because of placental hypoxia in the pre-eclamptic women, indicating that upstream molecular defect(s) may contribute to pre-eclampsia. Here we show that pregnant mice deficient in catechol-O-methyltransferase (COMT) show a pre-eclampsia-like phenotype resulting from an absence of 2-methoxyoestradiol (2-ME), a natural metabolite of oestradiol that is elevated during the third trimester of normal human pregnancy. 2-ME ameliorates all pre-eclampsia-like features without toxicity in the Comt(-/-) pregnant mice and suppresses placental hypoxia, hypoxia-inducible factor-1alpha expression and sFLT-1 elevation. The levels of COMT and 2-ME are significantly lower in women with severe pre-eclampsia. Our studies identify a genetic mouse model for pre-eclampsia and suggest that 2-ME may have utility as a plasma and urine diagnostic marker for this disease, and may also serve as a therapeutic supplement to prevent or treat this disorder.     

Further evidence for the dissociation of digoxin-like immunoreactivity from Na+,K(+)-ATPase inhibitory activity

The effects of adrenalectomy or nephrectomy, carried out one hour previously, on the levels of endogenous digitalis-like factors were determined in rat plasma. Factors were assayed by digoxin-like immunoreactivity and direct Na+,K(+)-ATPase inhibitory activity. Digoxin-like immunoreactivity significantly decreased one hour after bilateral ablation of adrenals, while Na+,K(+)-ATPase inhibitory activity remained unaltered. There were no changes in either activity one hour after bilateral nephrectomy. These results suggest that digoxin-like immunoreactivity may be derived from the adrenal gland or under adrenal control and the major substances detected by digoxin-like immunoreactivity and direct Na+,K(+)-ATPase inhibitory activity may be different.     

Functional DNA Materials Controlled by Surrounding Conditions

1 Results Addressable, controllable, and switchable supramolecular devices can provide keys to regulate the structure and function of nanomaterials. From this viewpoint, oligonucleotides are promising supramolecular materials because their assembly is addressable and they can be programmed. The G-quadruplexes of the oligonucleotide possess at least two important aspects: functions in vivo and applications in vitro. In addition, it is demonstrated that the G-quadruplex is promising for nanomolecular mach...