亚血红素的合成和纯化方法的改进

以血红素为原料 ,用间苯二酚作还原剂 ,将血红素还原为亚血红素 ,并用硅胶柱分离纯化 ,得到纯品亚血红素 .此种分离纯化方法简单 ,快速 ,得到的亚血红素纯度较高 ,可以为有机合成提供高纯度的原材料     

Cell density-induced changes in lipid composition and intracellular trafficking

Cell density is one of the extrinsic factors to which cells adapt their physiology when grown in culture. However, little is known about the molecular changes which occur during cell growth and how cellular responses are then modulated. In many cases, inhibitors, drugs or growth factors used for in vitro studies change the rate of cell proliferation, resulting in different cell densities in control and treated samples. Therefore, for a comprehensive data analysis, it is essential to understand the implications of cell density on the molecular level. In this study, we have investigated how lipid composition changes during cell growth, and the consequences it has for transport of Shiga toxin. By quantifying 308 individual lipid species from 17 different lipid classes, we have found that the levels and species distribution of several lipids change during cell growth, with the major changes observed for diacylglycerols, phosphatidic acids, cholesterol esters, and lysophosphatidylethanolamines. In addition, there is a reduced binding and retrograde transport of Shiga toxin in high density cells which lead to reduced intoxication by the toxin. In conclusion, our data provide novel information on how lipid composition changes during cell growth in culture, and how these changes can modulate intracellular trafficking.     

Interannual variability in the oxygen isotopes of atmospheric CO2 driven by El Niño

The stable isotope ratios of atmospheric CO(2) ((18)O/(16)O and (13)C/(12)C) have been monitored since 1977 to improve our understanding of the global carbon cycle, because biosphere-atmosphere exchange fluxes affect the different atomic masses in a measurable way. Interpreting the (18)O/(16)O variability has proved difficult, however, because oxygen isotopes in CO(2) are influenced by both the carbon cycle and the water cycle. Previous attention focused on the decreasing (18)O/(16)O ratio in the 1990s, observed by the global Cooperative Air Sampling Network of the US National Oceanic and Atmospheric Administration Earth System Research Laboratory. This decrease was attributed variously to a number of processes including an increase in Northern Hemisphere soil respiration; a global increase in C(4) crops at the expense of C(3) forests; and environmental conditions, such as atmospheric turbulence and solar radiation, that affect CO(2) exchange between leaves and the atmosphere. Here we present 30 years' worth of data on (18)O/(16)O in CO(2) from the Scripps Institution of Oceanography global flask network and show that the interannual variability is strongly related to the El Ni?o/Southern Oscillation. We suggest that the redistribution of moisture and rainfall in the tropics during an El Ni?o increases the (18)O/(16)O ratio of precipitation and plant water, and that this signal is then passed on to atmospheric CO(2) by biosphere-atmosphere gas exchange. We show how the decay time of the El Ni?o anomaly in this data set can be useful in constraining global gross primary production. Our analysis shows a rapid recovery from El Ni?o events, implying a shorter cycling time of CO(2) with respect to the terrestrial biosphere and oceans than previously estimated. Our analysis suggests that current estimates of global gross primary production, of 120 petagrams of carbon per year, may be too low, and that a best guess of 150-175 petagrams of carbon per year better reflects the observed rapid cycling of CO(2). Although still tentative, such a revision would present a new benchmark by which to evaluate global biospheric carbon cycling models.     

The nutritional incidence of flavonoids: some physiological and metabolic considerations

Examination of the physiological activity of flavonoids in relation to their antiscorbutic properties shows that some of these compounds, the flavan-3-ols, have a particular nutritional impact and consequently should be distinguished from the rest of the flavonoids and polyphenols. Therefore, the use of the term 'Vitamin P' and 'Bioflavonoids' is also discussed.     

Sur certaines conditions de la transformation du type antigénique et de l'équipement enzymatique d'un colibacille,sous l'effet d'un principe inducteur de nature thymonucléique issu d'un autre colibacille (mutation « dirigée »)

Summary The transformation of antigenic and enzymatic properties of a bacteria can be produced by the action of an inductor thymonucleic factor, which comes from a related bacteria. However, this transformation is only possible when the bacteria which must undergo the mutation dirigée is in a state of pronounced instability, the determinism of which is still unknown. We find to-day the greatest difficulties to isolate, without destroying it, the inductor factor, because it is very sensitive to bacterial enzyms and to the delayed action of acids and bases.     

DMP1 mutations in autosomal recessive hypophosphatemia implicate a bone matrix protein in the regulation of phosphate homeostasis

Hypophosphatemia is a genetically heterogeneous disease. Here, we mapped an autosomal recessive form (designated ARHP) to chromosome 4q21 and identified homozygous mutations in DMP1 (dentin matrix protein 1), which encodes a non-collagenous bone matrix protein expressed in osteoblasts and osteocytes. Intact plasma levels of the phosphaturic protein FGF23 were clearly elevated in two of four affected individuals, providing a possible explanation for the phosphaturia and inappropriately normal 1,25(OH)2D levels and suggesting that DMP1 may regulate FGF23 expression.     

Chronic active hepatitis in mice induced by 3-hydroxy-4-pyrone

Summary Chronic active hepatitis was selectively induced in mice by the feeding of a diet containing 3-hydroxy-4-pyrone (0.5% by weight) for periods of 6 weeks and longer. This model should be of particular value in elucidating the pathogenesis of drug-induced forms of chronic active hepatitis. Maltol (3-hydroxy-2-methyl-4-pyrone) did not produce any liver lesion.Acknowledgment. This research was supported in part by a grant from the Sir A.E. Rowden White Bequest to the Department of Pathology, University of Melbourne.To whom correspondance and requests for reprints should be addressed.     

Mediators of vascular remodelling co-opted for sequential steps in lung metastasis

Metastasis entails numerous biological functions that collectively enable cancerous cells from a primary site to disseminate and overtake distant organs. Using genetic and pharmacological approaches, we show that the epidermal growth factor receptor ligand epiregulin, the cyclooxygenase COX2, and the matrix metalloproteinases 1 and 2, when expressed in human breast cancer cells, collectively facilitate the assembly of new tumour blood vessels, the release of tumour cells into the circulation, and the breaching of lung capillaries by circulating tumour cells to seed pulmonary metastasis. These findings reveal how aggressive primary tumorigenic functions can be mechanistically coupled to greater lung metastatic potential, and how such biological activities may be therapeutically targeted with specific drug combinations.