Why do chlorosomal chlorophylls lack the C132 -methoxycarbonyl moiety? An in vitro model study

Effects of the C13²-methoxycarbonyl moiety on the self-assembly of chlorosomal chlorophylls (Chls) were studied. Model compounds, zinc methyl 3-devinyl-3-(1-hydroxymethyl)-pheophorbides a and a (Zn-3¹-OH-Chls a/a, C13²-epimers) were synthesized from Chl a, and their aggregation behaviors were examined in Triton X-100 (TX-100) micellar suspensions and in 6%THF/water, in comparison with those of a pyrolized derivative, zinc methyl 3-devinyl-3-(1-hydroxymethyl)-13²-demethoxycarbonyl-pheophorbide a (Zn-3¹-OH-pyroChl a). Zn-3¹-OH-Chl a formed self-aggregates in the TX-100 micellar suspension and gave a Q_y absorption peak at 703 nm, while Zn-3¹-OH-pyroChl a aggregates of a Q_y peak at 740 nm. In the Zn-3¹-OH-Chl a aggregate spectrum, the Q_y red-shift was smaller, the band shape was broader, and the contribution of the residual monomer was more intense than that in the Zn-3¹-OH-pyroChl a aggregate spectrum. The bulky C13²-moiety limits the ways of molecular association, and electronic interaction between the component molecules of the Zn-3¹-OH-Chl a aggregate is weakened. Stereoselective control of the aggregation of the C13²-epimer was also examined.     

Induction of osteoblast differentiation indices by statins in MC3T3-E1 cells

Statins inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which catalyzes conversion of HMG-CoA to mevalonate, a rate-limiting step in cholesterol synthesis. The present study was undertaken to understand the events of osteoblast differentiation induced by statins. Simvastatin at 10(-7) M markedly increased mRNA expression for bone morphogenetic protein-2 (BMP-2), vascular endothelial growth factor (VEGF), alkaline phosphatase, type I collagen, bone sialoprotein, and osteocalcin (OCN) in nontransformed osteoblastic cells (MC3T3-E1), while suppressing gene expression for collagenase-1, and collagenase-3. Extracellular accumulation of proteins such as VEGF, OCN, collagenase-digestive proteins, and noncollagenous proteins was increased in the cells treated with 10(-7) M simvastatin, or 10(-8) M cerivastatin. In the culture of MC3T3-E1 cells, statins stimulated mineralization; pretreating MC3T3-E1 cells with mevalonate, or geranylgeranyl pyrophosphate (a mevalonate metabolite) abolished statin-induced mineralization. Statins stimulate osteoblast differentiation in vitro, and may hold promise drugs for the treatment of osteoporosis in the future.     

The role of the C-terminal tail in protease-activated receptor-2-mediated Ca2+ signalling, proline-rich tyrosine kinase-2 activation, and mitogen-activated protein kinase activity

C-terminal truncation mutants were made to investigate the role of the C-terminus in coupling proteinase-activated receptor-2 (PAR-2) to various signalling pathways. Membrane expression of the delta15, delta34, delta43, and delta34-43 mutants was similar; however, expression of deltatail was lost, as was agonist-mediated internalisation of deltatail, delta43, and delta34-43. Additionally, trypsin and SLIGKV-stimulated [3H]IP accumulation was abrogated in cells transiently expressing delta43 or delta34-43 truncations, but remained unaffected in cells expressing delta34 or delta15. PAR-2 agonist-stimulated intracellular Ca(2+) mobilisation and PYK-2 activity were also abolished by deltatail, delta43, and delta34-43 mutants. However, trypsin-stimulated stress-activated protein kinases (SAPKs) or extracellular signal-regulated kinase (ERK) activities were unaffected by the delta34-43 mutation, although activity was abrogated following delta43 or deltatail truncations, suggesting that Ca(2+) mobilisation, PYK-2, or receptor internalisation are not requied for activation of SAPKs or ERK. These studies identify a novel sequence within the PAR-2 C-terminus essential for InsP(3) generation and PYK-2 activity but not mitogen-activated protein kinase (MAPK) activation.     

Novel chiral sulfur-containing ferrocenyl ligands for palladium-catalyzed asymmetric allylic substitution

New chiral ferrocenyl ligands having chiral sulfinyl and phosphinyl groups were prepared. The palladium-catalyzed allylic substitution reaction using these chiral ligands showed good enantioselectivity. The mechanism for the asymmetric reaction is proposed on the basis of the stereochemical outcome.     

Maillard reaction rate in various glassy matrices

The Maillard Reaction (MR) rate below the glass transition temperature (T(g)) for various model glassy food systems was studied at temperatures between 40 degrees C and 70 degrees C. As a sample, freeze-dried glucose and lysine systems embedded in various glassy matrices (e.g., polyvinylpyrrolodone and trehalose) were used, and the MR rate below the T(g) was compared among the various glassy matrices. The extent of MR was estimated spectrophotometrically from the optical density at 280 nm (OD(280)), and the MR rate (k(280)) was determined as a pseudo zero order reaction rate from the time course of OD(280). Although k(280) was described by the Arrhenius plot, the temperature dependence of k(280) was almost the same and the intercept was different among the matrices. From the comparison of k(280), it was suggested that the MR rate in glassy matrix was affected not only by the T(g), but also by the hydrogen bonding between MR reactants and glassy matrix.     

Bed rest attenuates sympathetic and pressor responses to isometric exercise in antigravity leg muscles in humans

Although spaceflight and bed rest are known to cause muscular atrophy in the antigravity muscles of the legs, the changes in sympathetic and cardiovascular responses to exercises using the atrophied muscles remain unknown. We hypothesized that bed rest would augment sympathetic responses to isometric exercise using antigravity leg muscles in humans. Ten healthy male volunteers were subjected to 14-day 6 degrees head-down bed rest. Before and after bed rest, they performed isometric exercises using leg (plantar flexion) and forearm (handgrip) muscles, followed by 2-min postexercise muscle ischemia (PEMI) that continues to stimulate the muscle metaboreflex. These exercises were sustained to fatigue. We measured muscle sympathetic nerve activity (MSNA) in the contralateral resting leg by microneurography. In both pre- and post-bed-rest exercise tests, exercise intensities were set at 30 and 70% of the maximum voluntary force measured before bed rest. Bed rest attenuated the increase in MSNA in response to fatiguing plantar flexion by approximately 70% at both exercise intensities (both P < 0.05 vs. before bed rest) and reduced the maximal voluntary force of plantar flexion by 15%. In contrast, bed rest did not alter the increase in MSNA response to fatiguing handgrip and had no effects on the maximal voluntary force of handgrip. Although PEMI sustained MSNA activation before bed rest in all trials, bed rest entirely eliminated the PEMI-induced increase in MSNA in leg exercises but partially attenuated it in forearm exercises. These results do not support our hypothesis but indicate that bed rest causes a reduction in isometric exercise-induced sympathetic activation in (probably atrophied) antigravity leg muscles.     

Effects of specific signal transduction inhibitors on increased permeability across rat endothelial monolayers induced by neuropeptide Y or VEGF

Neuropeptide Y (NPY) elevates the permeability of cultured rat aortic endothelial cells (RAECs) in monolayer cultures under hypoxic conditions (5% O(2)) possibly by binding to the NPY Y(3) receptor. The present study evaluated the effects of NPY compared to vascular endothelial growth factor (VEGF). RAECs were cultured on the upper chamber base of a double-chamber culture system, FITC-labeled albumin was introduced into the chamber, and permeation into the lower chamber was measured. Treatment was with 3 x 10(-7) M NPY or 10(-7) g/ml VEGF for 2 h along with specific inhibitors. The VEGF receptor-2 tyrosine kinase inhibitor tyrphostin SU-1498 and the protein kinase C inhibitor bis-indolylmaleimide I (GF-109203X) suppressed the VEGF-induced increase in monolayer permeability but not that caused by NPY. Furthermore, although the action of NPY was blocked in a concentration-dependent manner by phospholipase C inhibitor 1-(6-[[(17beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl)-1H-pyrrole-2,5-dione (U-73122), it was less sensitive than VEGF. However, the effects of both NPY and VEGF on the permeability of the RAEC monolayer were blocked with equal concentration dependence by STI571 (imatinib mesylate), which is an inhibitor of Abl tyrosine kinase in the nucleus and/or cytoplasm. The myosin light-chain kinase inhibitor 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine HCl (ML-9) suppressed both NPY- and VEGF-induced increment in permeability by approximately 70%, whereas the calmodulin-dependent kinase inhibitor DY-9760e could decrease to below the baseline. These results indicate that the NPY Y(3)-receptor subtype is specifically linked to the effects of STI571 on endothelial cells, and that NPY, a sympathetic coneurotransmitter, may increase vascular permeability in association with altered intracellular or nuclear signal transduction.     

Target proteins of the cytosolic thioredoxins in Arabidopsis thaliana

Possible target proteins of cytosolic thioredoxin in higher plants have been investigated in the cell lysate of dark-grown Arabidopsis thaliana whole tissues. We immobilized a mutant of cytosolic thioredoxin, in which an internal cysteine at the active site was substituted with serine, on CNBr activated resin, and used the resin for the thioredoxin-affinity chromatography. By using this resin, the target proteins for thioredoxin in the higher plant cytosol were efficiently acquired. The obtained proteins were separated by two-dimensional gel electrophoresis and analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Thus we have identified proteins of the anti-oxidative stress system proteins (ascorbate peroxidase, germin-like protein, and monomeric type II peroxiredoxin), proteins involved in protein biosynthesis (elongation factor-2 and eukaryotic translation initiation factor 4A), proteins involved in protein degradation (the regulatory subunit of 26S proteasome), and several metabolic enzymes (alcohol dehydrogenase, fructose 1,6-bis phosphate aldolase-like protein, cytosolic glyceraldehyde 3-phosphate dehydrogenase, cytosolic malate dehydrogenase, and vitamin B(12)-independent methionine synthase) together with some chloroplast proteins (chaperonin 60-alpha and 60-beta, heat shock protein 70, and glutamine synthase). The results in this study and recent proteomics studies on the target proteins of chloroplast thioredoxin indicate the versatility and the physiological significance of thioredoxin as reductant in plant cell.     

Serum concentrations of androstenediol and androstenediol sulfate, and their relation to cytokine production during and after normal pregnancy

Since it is known that androstenediol (ADIOL) has potent immunoregulatory effects, changes in ADIOL levels during and after pregnancy might affect the maternal immune system. We examined serum concentrations of ADIOL and androstenediol 3-sulfate (ADIOLS) together with IFN-gamma and IL-4 production levels during pregnancy and after delivery up to 10-11 months postpartum. The subjects were 73 normal pregnant, 76 normal postpartum, and 28 normal non-pregnant women. ADIOL and ADIOLS were measured using EIA and GC/MS, respectively. The cytokine levels in the supernatant of whole-blood cultures stimulated with phorbol 12-myristate 13-acetate and ionomycin were measured using ELISA. ADIOL levels significantly decreased compared to non-pregnant levels in the first trimester (P < 0.05) and were reversed in the third trimester (P < 0.05). After pregnancy, ADIOL levels gradually declined, and a significant decrease was observed at 10-11 months postpartum (P < 0.05). ADIOLS levels were significantly lower in the third trimester (P < 0.05) and significantly higher at the first month postpartum (P < 0.001) compared to non-pregnant women. IFN-gamma and IL-4 levels decreased during pregnancy and subsequently increased postpartum. On the other hand, we found significant negative correlations between ADIOL concentrations and production levels of IFN-gamma (P < 0.05) or IL-4 (P < 0.05). These findings suggest that ADIOL may be involved in modifying the maternal immune response during and after pregnancy.