Evidence for a critical role for IL-2 in CD40-mediated activation of naive B cells by primary CD4 T cells

The interaction of CD40 on B cells with the CD40 ligand (CD40L) on preactivated CD4 T cells is critical for the initiation of T-dependent Ab responses. It is believed that signals via CD40 synergize with cytokines (e.g., IL-4 and IL-5) to drive B cell activation. However, primary T cells preactivated via CD3 alone cannot induce B cell proliferation; we have shown previously that costimulation of T cells via CD3 and CD28 stabilizes the expression of the CD40L, which we propose contributes to their capacity to act as competent helper-effector cells. Here we show that an additional, critical reason why CD3-stimulated CD40L-bearing T cells are incompetent helper cells is because they secrete insufficient IL-2. In contrast, CD28/CD3-activated T cells induce B cells to become IL-2 responsive via a combination of CD40L and IL-2-mediated signals, and these two stimuli subsequently drive B cell proliferation and IgM secretion. We therefore propose that T cells must first encounter Ag in conjunction with CD80/86 on APCs. This leads to the stable expression of CD40L and maximal secretion of IL-2, which together render primary T cells competent to activate B cells in an IL-2-dependent fashion.     

Mass spectrometric analysis of mono- and dialkyl ethers of diols

Mass spectra of homologous series of long chain mono- and dialkyl ethers of ethanediol and propanediols were measured and general patterns of fragmentation were established. Both classes of diol lipids produce ions which are characteristic for the alkoxy moieties as well as ions which are typical of the constituent short chain diols. Prominent ions are formed by cleavages α and β to the ether oxygen and by rearrangement of one or two hydrogens and concurrent fission. High resolution mass spectrometry and deuterium labeling techniques were used to verify the composition of ions and to substantiate fragmentation mechanisms. Part VIII in the series “Naturally Occurring Diol Lipids” (part VII is Reference 1) and part IX in the series “Mass Spectrometry of Lipids” (part VIII is Reference 1).     

Comparison of pyrrolidides with other amides for mass spectral determination of structure of unsaturated fatty acids

Amides of unsaturated fatty acids give mass spectra which indicate the locations of the double bonds. A survey of several amides of oleic acid was made to evaluate which amide might be most suitable for routine use in elucidation of structure. Methods of preparation of several amides of oleic acid are presented with mass spectral and gas chromatographic data. Tertiary amides have most easily interpretable mass psectra which indicate the position of the double bond in the fatty acid chain. The pyrrolidide is advantageous for fatty acid gas liquid chromatography and mass spectrometry analyses because it can be prepared easily in high yield on a microscale, it is volatile enough for gas liquid chromatographic separations, and it has a simple and easily interpretable mass spectrum which indicates the structure.     

Desaturation of isomericcis 18∶1 acids

The desaturation of positionalcis 18∶1 isomers (Δ4 through Δ11) was studied, using essential fatty acid deficient rat liver microsomes. Thecis Δ4, Δ5, Δ6 and Δ7 isomers were not desaturated. Thecis Δ10 and Δ11 isomers were desaturated at a very low rate. The maximum desaturation was obtained for Δ8 and Δ9 isomers. Thecis Δ8 and Δ11 isomers were desaturated by Δ5 desaturase; thecis Δ9 isomer was desaturated by Δ6 desaturase; and thecis Δ10 isomer was desaturated to Δ7,10 and 5,10–18∶2 acids.     

Mass spectrometry of lipids. II. Monoglycerides,their diacetyl derivatives and their trimethylsilyl ethers

The mass spectra of 1- and 2-monoglycerides, their diacetyl derivatives and their trimethylsilyl (TMS) ether derivatives were recorded at high (80 eV) and low (6–13 eV) voltages. The fatty acid components of these derivatives included the even-numbered saturated acids from capric to arachidic acid plus oleic, linoleic and linolenic acids. Differences between isomeric 1- and 2-monoglycerides were not sufficient to provide a basis for the analysis of these isomers. Mass spectra of the monoglycerides were very similar to the corresponding methyl esters. Mass spectra of the diacetyl derivatives were qualitatively similar to triglycerides of long-chain fatty acids, but parent ions were not observed. The spectra of diacetyl derivatives may be used for distinguishing 1- and 2-monoglycerides, but the spectra of the TMS ethers are better in this regard. The latter derivatives have fragmentation patterns distinct for the 1- and 2-monoglyceride isomers, particularly at low electron voltages. For the first paper in this series, see reference 1.     

Fatty acid distribution in the bovine pre- and postpartum testis

Testes from fetuses, calves, bulls and recently castrated animals were analyzed for total lipids, lecithin, cephalin, triglycerides, diglycerides, cholesteryl esters and cholesterol. Total lipids increase somewhat with age, but in the castrated animal the increase is more marked. Phospholipid content increases with age, but decreases in the castrated animal. Cholesterol decreases and triglyceride increases after birth and in the castrated animal. Polyunsaturated acids increase with age in all lipid classes. Eicosatrienoic acid is more abundant in fetal testicular lipids than in testes removed after birth. In the castrated testis there is a general decrease in the unsaturated fatty acids. Acids of the ω6 family are the predominant polyunsaturated acids and increase somewhat with age in all lipids. The ω3 family of polyunsaturated acids appears mostly toward the end of fetal life and increases after birth. Acids of the linoleate family reach approximately 25% of total acids in most lipid classes at maturity whereas the ω3 acids range from 1 to 9%. Presented at the American Dairy Science Association Meeting, Lexington, Ky., June 1965.     

Mass spectrometry of lipids. I. Cyclopropane fatty acid esters

A method was developed for the almost quantitative conversion of unsaturated esters (from monoenes to tetraenes) to cyclopropanes using diiodomethane and a highly active zinc-copper couple. These derivatives are sufficiently volatile for GLC analysis andcis andtrans isomers can be distinguished by this technique. Equivalent chain lengths of the cyclopropane derivatives were measured on polar and nonpolar phases. The mass spectra of the monocyclopropane compounds are very similar to those of the parent unsaturated esters. Those of dicyclopropanes, however, are quite distinctive so that the original structure of the ester can be deduced. Polycyclopropanes give complex spectra which are difficult to interpret in terms of the position of the original double bonds. Presented at the Symposium on Spectrometry Applied to Lipids, AOCS Meeting, Cincinnati, October, 1965.     

Dietary fats containing concentrates ofcis ortrans octadecenoates and the patterns of polyunsaturated fatty acids of liver phosphatidylcholine and phosphatidylethanolamine

The effects of the mixedcis- 18∶1 isomers and mixedtrans-18∶1 isomers present in partially hydrogenated soybean oil (PHSO) upon the patterns of polyunsaturated fatty acids (PUFA) in liver phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were studied in rats fed concentrates ofcis- 18∶1 ortrans- 18∶1 isomers isolated as triacylglycerides from PHSO. Thecis- 18∶1 andtrans- 18∶1 concentrates were fed at levels equal to those present in PHSO fed at 17.9% of the diet. All diets contained the required amounts of both linoleic and linolenic acids. Thetrans- 18∶1 concentrate was found to suppress the levels of 20∶4ω6 and 20∶3ω9, and to increase the levels of 18∶2ω6 and 20∶5ω3 in PC and PE. Thecis- 18∶1 concentrate suppressed 20∶4ω6 in PC, 20∶5ω3 in PC and PE, and 18∶2ω6 was more effective than thetrans concentrate in suppressing 22∶6ω3. Thetrans- 18∶1 concentrate was more effective in suppressing 20∶4ω6. Thetrans-18∶ isomers appear to modify PUFA metabolism by inhibition of PUFA synthesis, whereas thecis- 18∶1isomers appear to compete with 2-position fatty acyl transfer and to inhibit ω3 PUFA acylation.     

Effect of torus wall flexibility on hydro-structure interaction in BWR containment system

This paper describes an analytical project that employs the finite element method to investigate the influence of torus wall flexibility on hydrodynamically induced pressure and the resultant force on the torus shell surface in a Mark I BWR containment system. The shell flexibility is characterized by the diameter-to-thickness ratio, which is varied from the perfectly rigid case to the nominal plant condition.The general conclusion reached is that torus wall flexibility decreases both the maximum pressure seen by the shell wall and the total vertical load that results from the hydrodynamically induced pressure. This conclusion is based on results of a comprehensive two-dimensional investigation and a more sophisticated three-dimensional confirmatory study of the hydro-structural interaction problem.     

Titration without Mixing or Dilution: Sequential Injection of Chemical Sensing Membranes

A novel, miniaturized titration was developed using beads 35 μm in diameter as semisolid aqueous titrant retained in a nonaqueous sample stream. Agarose beads with internally bound pH indicator served as a pH sensing membrane material swollen with aqueous NaOH titrant. The indicator monitored the remaining titrant within the agarose beads during perfusion with H(2)SO(4) in 1-butanol samples. Irreversible reaction of 2 mg bead layers was made possible by automated packing and disposal in a flow cell. This strategy substituted membrane advantages for the burdens of mixing and unnecessary dilution under laminar flow conditions. The agarose environment was conditioned with NaCl to tolerate dissolved salt in the sample. Transmittance measurements were made via fiber optics through FEP PTFE optical windows. A simple inverse relationship held between endpoint volume and acid concentration so that calibration curves were linear, R(2) = 0.9980.