Free fatty acids inhibit cytotoxic T lymphocyte-mediated lysis of allogeneic target cells

Short term exposure of murine CTL clones to long chain cis unsaturated free fatty acid (FFA) inhibits alloantigen specific lysis of cognate target cells, whereas long-chain saturated FFA have no effect. Inhibition of lysis occurs when cis FFA is added before or within 10 min after CTL-target cell conjugate formation and thus appears to interfere with lethal hit delivery. Our previous studies have shown that similar treatment with cis FFA inhibits, in CTL, the Ag stimulated increase in intracellular calcium and degranulation, suggesting that inhibition of lysis probably results from perturbation of the CTL signaling pathway. However, inhibition of lysis is probably not due to the inhibition of the rise in intracellular calcium or degranulation, because lysis can occur under conditions in which FFA inhibit degranulation and because cis FFA inhibit calcium-independent killing. Inhibition of lysis is detectable at unbound FFA concentrations less than 1 microM and is generally complete at concentrations less than 5 microM. Although these levels of FFA are somewhat higher than reported for normal physiologic conditions, plasma FFA levels can be elevated into this range in states of stress and disease, suggesting that FFA modulation of the immune response has important physiologic consequences.     

Zidovudine (azido dideoxythymidine) inhibits characteristic early alterations of lymphoid cell populations in retrovirus-induced murine AIDS

Using flow cytometry technology and multiparameter analyses, we report early and characteristic alterations in lymphoid cell profile in spleen and lymph nodes due to LP-BM5 retrovirus disease (murine AIDS (MAIDS)) and the effect of azido dideoxythymidine, a nucleoside inhibitor, on these changes. MAIDS has been characterized by rapid and profound lymphoproliferation accompanied by hypergammaglobulinemia and immunosuppression. As early as 2 wk postinfection, there is a selective depletion of CD8+ cells whereas the total number of CD4+ cells increases throughout the first 8 wk of infection although the frequency is relatively stable. These population changes were partially delayed by oral AZT therapy for 6 wk postinfection. Ly-6C (AL-21) is expressed on roughly 50% of CD4+ and CD8+ cells in C57BL/6 mice. In MAIDS, the residual population of CD8+ cells is primarily Ly-6C+. The CD4+ cells have a transient increase in ratio of Ly-6C+/Ly-6C- cells at 2 wk postinfection but by 6 wk are primarily Ly-6C-. There was an increase in both the total number and percentage of Mac 1+ cells and a selective depletion of certain splenic B cell subpopulations. Azido dideoxythymidine delays these early population changes.     

Cross-linkage sites in type I collagen fibrils studied by neutron diffraction

Cross-links in tendon collagen are essential for the biomechanical strength of healthy tissue. The nature and position of these cross-links has long been a subject for conjecture. We have approached this problem in a non-destructive manner, by studying neutron diffraction from collagen fibrils that have been specifically deuterated by reduction at keto-amine and Schiff base groups with sodium borodeuteride (NaB2H4). The intensities of the first 23 meridional reflections were recorded for both native and reduced tendons. These data were used to calculate the neutron-scattering density profile of the 67 nm (D) repeat of type I collagen fibrils in rat tail tendon. This approach not only succeeds in determining the location of the cross-linkage sites with respect to the fibril structure, as projected onto the fibre axis, but also presents a novel form of the isomorphous derivative solution to the phase problem.     

Structure of the accessory reproductive glands of the male migratory grasshopper,Melanoplus sanguinipes

The accessory reproductive glands of Melanoplus sanguinipes comprise two bilateral masses of 16 tubules each, distinguishable in sexually mature insects as four white, ten short hyaline, one long hyaline, and a seminal vesicle. Over most of its length, the wall of each tubule consists of a simple glandular epithelium resting on a basal lamina, surrounded by a thin layer of circular muscle. However, near the junction with the ejaculatory duct, the wall of each tubule has a much thickened circular muscle layer and squamous or cuboidal epithelium, the region serving to regulate movement of secretion into the ejaculatory duct. Interdigitation of adjacent epithelial cells is common, and several kinds of specialized junctions occur. In the glandular region, all epithelial cells appear the same and may be flattened, cuboidal, or columnar depending on the tubule type. Except for those of the seminal vesicle, the glandular epithelial cells share ultrastructural features typical of cells engaged in the synthesis of protein for export. Despite these general similarities, in most instances subtle differences occur in the cellular ultrastructure of the epithelia of each tubule and in the appearance of their luminal secretions, suggesting that the tubules are functionally specialized.     

Serum hormones and physical performance capacity in young boy athletes during a 1-year training period

Serum hormones and physical performance capacity in boy athletes (AG; n = 19) were investigated during a 1-year training period (between the ages of 11.6 and 12.6 years). Six young untrained boys served as the control group (CG). The mean serum testosterone concentration increased significantly in AG (P less than 0.05) following the training period from 2.92 nmol.l-1, SD 1.04 to 5.81 nmol.l-1, SD 1.33. Significant differences were not observed in the cortisol, sex hormone binding globulin and growth hormone levels during the follow-up period. The AG clearly increased speed (P less than 0.001), speed-strength (P less than 0.01-P less than 0.001) and anaerobic capacity (P less than 0.001) whereas CG had only slight increases (NS) in physical performance capacity during a 1-year period. During the last 6-month training period significant positive correlations (r = 0.49-0.58; P less than 0.05-P less than 0.01) were observed in AG between the relative changes in testosterone, testosterone:cortisol ratio and growth hormone and the relative performance change in speed, maximal isometric force and endurance, respectively. At the end of the period significant positive correlations were observed in all subjects between the level of testosterone and speed-strength (r = 0.52-0.64; P less than 0.01-P less than 0.001) and anaerobic capacity (r = 0.49; P less than 0.05). It was concluded that an increase in anabolic activity with the synchronous training already has positive effects on trainability and physical performance capacity at an early stage in puberty.     

Effects of prepubertal castration on the spinal motor nucleus of the ischiocavernosus muscle of the rat

Summary The location, number and size of the motoneurons innervating the ischiocavernosus muscle, identified by means of horseradish-peroxidase (HRP) retrograde transport, were studied (1) in adult untreated male rats, (2) in adult male rats castrated before puberty, and (3) in adult male rats castrated before puberty and injected with testosterone from the day of castration. After injection of HRP into the ischiocavernosus muscle, labeled motoneurons were found in the dorsolateral and dorsomedial columns of the lamina IX, at the level of L6 and S1 segments of the spinal cord. Morphometric analysis demonstrated that prepubertal castration induces a statistically significant reduction in the somatic and nuclear areas (40% and 35%, respectively, if compared to those of the control rats) of both the dorsolateral and dorsomedial motoneurons, but does not affect their number. The effects of castration are prevented by exogenous testosterone.Preliminary results were presented at the International Conference on Hormones, Brain and Behaviour, Liège, Belgium, August, 1989     

The Effects of Brown Rust and Phosphate on Cold Acclimation in Winter Barley

The green leaf area of winter barley, cv. Sonja, sampled fromthe field at different times during winter was always greatestin plants grown at high soil phosphate and smallest in plantsgrown at low soil phosphate, and at each fertilizer level wasgreater in healthy plants than in plants infected by rust (Pucciniahordei). In leaves that survived the coldest period of winter,the percentage area that was damaged was increased by rust infectionwhich prevented the ameliorating effects of high soil P. Rustand low P interacted to reduce the increases in leaf area andshoot d. wt that occurred when higher temperatures prevailedin spring. Under controlled conditions in the laboratory, phosphate reducedthe injury suffered when plants not acclimated to low temperatureswere exposed to freezing conditions, but this effect was removedby rust infection. After rust infection, freezing temperatureswere damaging even to acclimated plants, particularly if grownwith low soil P. Evidence of visible symptoms, and quantitativemeasurements of electrolyte efflux from intact leaves, chlorophyllfluorescence in vivo, and ethane and ethylene evolution fromcold-acclimated plants, showed that infection raised the minimumtemperature at which tissues could survive without injury. Infectedleaves were more sensitive to low temperature post-sporulationthan presporulation. Measurements of electrolyte efflux andchlorophyll fluorescence on plants growing under cold conditionsshowed that infection inhibited the processes of acclimationto low temperatures. Winter barley, Puccinia hordei, injury, low temperature, acclimation     

Composition of fatty acids and sphingosine bases of placental gangliosides

The fatty acids and sphingosine bases from major placenta gangliosides (NeuAcLacCer, IV3NeuAc-nLc4Cer, VI3NeuAc-nLc6Cer, (NeuAc)2LacCer, II3IV3(NeuAc)2Gg4Cer and VI3NeuAc, IV6(II3NeuAc-nLcNAc)-nLc6Cer) were studied. The C18-sphingenine was shown to be present in all ganglioside fractions; fraction GD1a contained, in addition, C20-sphingenine. Saturated fatty acids were identified as major fatty acid fragments. The content of long-chain acids (22-25 C-atoms) in the monosialogangliosides was much higher than that in disialogangliosides.