A thermochemical study of metabolic pathways in activated and triggered 2C11–12 mouse macrophage hybridoma cells

Hybridization with lymphosarcoma cells immortalized mouse macrophages for the study of phagocytosis and cytobicidal properties. In the study of macrophage physiology, it became necessary to know more of their cellular metabolism and the changes which occurred when the cells were triggered into the respiratory burst. It was found that, in common with many other types of growing cell, activated 2C11-12 macrophage hybridomas produced considerable lactate under fully aerobic conditions, judging from the highly exothermic CR ratio and subsequent spectrophotometric analysis. Most of both the substrates (glucose and glutamine) was converted to lactate, respectively, by glycolysis and glutaminolysis, in the demand for biosythetic precursors during growth. Glucose was the more important energy source. Approximately 60% of heat production was explained in terms of enthalpy changes in glucose and glutamine metabolism. It was suspected that fatty acid oxidation from contaminants in the bovine serum albumin needed for cell culture may be important in catabolism.

The respiratory burst was triggered by phorbol-12-myristate-13-acetate and recorded by greatly (5-fold) increased heat production and enhanced chemiluminescence. Oxygen consumption was very rapid and soon led to anoxia in the closed culture system. The calorimetric-respirometric (CR) ratio was less negative and analysis confirmed that there was less lactate production. Radioisotope studies indicated that glycolysis and glutaminolysis were less intensive, with respiration of glucose accounting for over 90% of the heat production. The imperative for producing NADPH and cytotoxic oxygen metabolites heavily biased catabolism, reducing the supply of biosynthetic precursors. Known sources of heat production accounted for 87% enthalpy recovery and the remainder may well be caused by fatty acid oxidation.     

婴幼儿肺炎并发呼吸衰竭时细胞内外钙浓度AAS法测定

本文采用氧化亚氮-乙炔-原子吸收法测定婴儿、幼儿细胞内外的钙,样品用三氯乙酸沉淀分离作前处理,以硝酸镧消除磷对钙的抑制干扰。本方法适应于医学单位常规分析中微量钙的分析,方法可靠和精确。     

Heavy metal—A contrasting substance for micro-tomographical visualization of scorpion book lungs

Remarkable results obtained while searching for suitable contrasting agents for tomographical imaging are presented. Book lungs, the respiratory organs of scorpions (Scorpiones, Arachnida), served as challenging objects in terms of fragility and preparatory requirements, as well in terms of size differences between the entire organ and its functional subunits (the lamellae). The problem of tissue contrast was investigated using various metals, but most successfully addressed using osmium. Gaseous osmium tetroxide exposure with subsequent ethanol treatment yielded the best results. A constant and thorough staining of the book lungs was achieved, easing book-lung visualization using 3D-reconstructions from μCT scans.     

Modelling the joint distribution of competing risks survival times using copula functions

The problem of modelling the joint distribution of survival times in a competing risks model, using copula functions, is considered. In order to evaluate this joint distribution and the related overall survival function, a system of non-linear differential equations is solved, which relates the crude and net survival functions of the modelled competing risks, through the copula. A similar approach to modelling dependent multiple decrements was applied by Carriere [Carriere, J., 1994. Dependent decrement theory. Transactions, Society of Actuaries XLVI, 45-65] who used a Gaussian copula applied to an incomplete double-decrement model which makes it difficult to calculate any actuarial functions and draw relevant conclusions. Here, we extend this methodology by studying the effect of complete and partial elimination of up to four competing risks on the overall survival function, the life expectancy and life annuity values. We further investigate how different choices of the copula function affect the resulting joint distribution of survival times and in particular the actuarial functions which are of importance in pricing life insurance and annuity products. For illustrative purposes, we have used a real data set and used extrapolation to prepare a complete multiple-decrement model up to age 120. Extensive numerical results illustrate the sensitivity of the model with respect to the choice of copula and its parameter(s).     

Effect of stereochemistry of Δlac-acetogenins on the inhibition of mitochondrial complex I (NADH-ubiquinone oxidoreductase)

Δlac-Acetogenins are a new type of inhibitors of bovine heart mitochondrial complex I (NADH-ubiquinone oxidoreductase). We synthesized a series of Δlac-acetogenins in which the stereochemistry around the hydroxylated tetrahydrofuran (THF) ring moiety was systematically modified, and examined their inhibitory effect on complex I. The present results revealed that the inhibitory effects of the bis-THF ring analogs are much more potent than those of the mono-THF ring analogs and that the stereochemistry around the bis-THF ring moiety significantly influences the inhibitory effect. The profiles of the structure-activity relationship observed for Δlac-acetogenins were entirely different from those for natural-type acetogenins.