RANKL stimulates proliferation, adhesion and IL-7 expression of thymic epithelial cells

In many clinical situations which cause thymic involution and thereby result in immune deficiency, T cells are the most often affected, leading to a prolonged deficiency of T cells. Since only the thymic-dependent T cell production pathway secures stable regeneration of fully mature T cells, seeking strategies to enhance thymic regeneration should be a key step in developing therapeutic methods for the treatment of these significant clinical problems. This study clearly shows that receptor activator of NF-kappaB ligand (RANKL) stimulates mouse thymic epithelial cell activities including cell proliferation, thymocyte adhesion to thymic epithelial cells, and the expression of cell death regulatory genes favoring cell survival, cell adhesion molecules such as ICAM-1 and VCAM-1, and thymopoietic factors including IL-7. Importantly, RANKL exhibited a significant capability to facilitate thymic regeneration in mice. In addition, this study demonstrates that RANKL acts directly on the thymus to activate thymus regeneration regardless of its potential influences on thymic regeneration through an indirect or systemic effect. In light of this, the present study provides a greater insight into the development of novel therapeutic strategies for effective thymus repopulation using RANKL in the design of therapies for many clinical conditions in which immune reconstitution is required.     

Alterations of proliferative and differentiation potentials of human embryonic stem cells during long-term culture

Human embryonic stem cells (hESCs) are considered to be able to stably maintain their characteristics in vitro for prolonged periods, but we had previously encountered changes in proliferative ability and differentiation potential during extended culture of hESCs. Therefore, we investigated the proliferative ability and differentiation potential of hESCs during long-term culture. The hESCs, SNUhES3, were used to analyze population-doubling time, proliferation rate and differentiation potential. We classified hESCs into three groups according to culture period. Ten colonies of hESCs for each group were daily measured colony area and population-doubling time was assessed by the changes of colony area. Proliferation rate of hESCs was measured by 5-bromo-2'-deoxyuridine (BrdU) assay and telomerase activity. To evaluate differentiation potentials for hESCs, expression levels of undifferentiated and/or differentiated hESCs markers were examined by FACS, RT-PCR and immunostaining. Population-doubling time of early passage hESCs was longer than those of middle or late passage. Proliferative ability of hESCs was accelerated depending on culture periods. Cellular morphologies and the expression level of each three germ layer markers were obviously different from each passage of reattached embryoid bodies (EBs) after spontaneous differentiation. Differentiated cells of late passage expressed higher levels of undifferentiated markers such as Oct4 and SSEA4 than those of early and middle passage. But differentiated cells of early and middle passage expressed higher level of differentiated state markers, Nestin (ectoderm), Brachyury (mesoderm), HNF3beta (endoderm). From these results, it can be inferred that hESCs show higher proliferative abilities and reduced differentiation potentials as the passage number increased. Therefore, we conclude that early passage hESCs could be more suitable than middle and late passage hESCs in differentiation studies.     

Pathobiological role of advanced glycation endproducts via mitogen-activated protein kinase dependent pathway in the diabetic vasculopathy

Advanced glycation endproducts (AGEs) have been reported to play a role in neointimal formation and increase the rate of in-stent restenosis (ISR) in the diabetic coronary artery disease patients treated with stents, but the potential pathogenic mechanisms of AGEs in vascular smooth muscle cell proliferation remain unclear. We sought to determine the AGEs related pathobiological mechanism of diabetic vasculopathy. Rat aortic smooth muscle cell (RAoSMC) culture was done with different concentrations of AGEs and proliferation was assessed. Immunohistochemistry for receptor of AGEs (RAGE) was performed with human carotid atheroma. Western blotting was performed to assess the activation of MAP kinase system in the cultured RAoSMC. AGEs increased RAoSMC proliferation and were associated with increased phosphorylation of ERK and p38 kinase by time and dose dependent manner. The MAP kinase activity was decreased by RNA interference for RAGE. AGEs stimulation increased reactive oxygen species (ROS) generation in cultured RAoSMC. From this study it is concluded that AGEs played a key role in RAoSMC proliferation via MAP kinase dependent pathways. Activation of vascular smooth muscle cell (VSMC) proliferation by MAP kinase system and increased formation of ROS may be the possible mechanisms of AGEs induced diabetic vasculopathy.     

Polymorphisms in two genes, IL-1B and ACE, are associated with erythropoietin resistance in Korean patients on maintenance hemodialysis

Genetic polymorphisms may be linked to inter-individual differences in erythropoietin (EPO) resistance. We investigated the -511C/T polymorphism of the IL-1B gene and the I/D polymorphism of the ACE gene for any association with EPO resistance index (ERI) in maintenance hemodialysis patients (n=167). Because EPO responsiveness is multi-factorial, we also included other possible influences (age, sex, time on dialysis, ACE inhibitor or angiotensin receptor blocker use, ferritin, transferrin saturation, intact PTH, high sensitivity C-reactive protein, albumin, Kt/V, and presence of diabetes mellitus) on ERI in our analyses. Multiple regression analysis showed significant association of the IL-1B-511CC and ACE DD polymorphisms with ERI (P=0.038 and P=0.004 in the recessive model, respectively). The combination (C) of alleles of two loci showed that C1 (I-T) was significantly associated with ERI in the co-dominant and recessive models (P=0.005 and P=0.0001, respectively). Subjects who did not carry C1 showed significantly decreased ERI (10.10+/-5.15 IU/kg weight/g hemoglobin) compared to other study subjects (C1/C1 and C1/-; 12.97+/-4.90 and 15.12+/-7.43 IU/kg weight/g hemoglobin, respectively). Our study indicates that the IL-1B-511C/T and ACE I/D polymorphisms may be useful genetic markers of EPO requirement in hemodialysis patients. These findings might also provide a new perspective on therapeutic approaches to the treatment of end stage renal disease patients with anemia.     

Endothelin 1 protects HN33 cells from serum deprivation-induced neuronal apoptosis through Ca(2+)-PKCalpha-ERK pathway

Endothelins (ETs), which were originally found to be potent vasoactive transmitters, were known to be implicated in nervous system, but the mode of mechanism remains unclear. ETs (ET-1, ET-2, and ET-3) were added to HN33 (mouse hippocampal neuron chi neuroblastoma) cells. Among the three types of ET, only ET-1 increased the intracellular calcium levels in a PLC dependent manner with the induction of ERK 1/2 activation. As the result of ET-1 exposure, the survival rate of HN33 cells and the PKCalpha translocation into the plasma membrane were increased. We suggest that ET-1 participated in the neuroprotective effect involving the calcium-PKCalpha-ERK1/2 pathway.     

Dialkylaminopyridine-functionalized mesoporous silica nanosphere as an efficient and highly stable heterogeneous nucleophilic catalyst

A new nucleophilic catalytic system comprised of dialkylaminopyridine-functionalized mesoporous silica nanosphere (DMAP-MSN) has been synthesized and characterized. We have demonstrated that this material is an efficient heterogeneous catalyst for Baylis-Hillman, acylation, and silylation reactions with good reactivity, product selectivity, and recyclability. We envision that this DMAP-functionalized mesoporous silica material can also serve as an effective heterogeneous catalyst for many other catalytic nucleophilic reactions.     

A new synthetic route to (North)-methanocarba nucleosides designed as A3 adenosine receptor agonists

Activation of the A3 adenosine receptor (AR) is associated with cerebroprotective, cardioprotective, and anticancer effects. Among potent and selective A3 AR agonists are novel methanocarba adenosine analogues in which the conformation of a pseudo-ribose moiety is locked in the North (N) hemisphere of the pseudorotational cycle. 5'-Uronamide (N)-methanocarba nucleosides, such as MRS1898 and MRS2346, are examples of full agonists of the human A3 AR. An improved convergent approach from easily accessible 2,3-O-isopropylidene-d-erythrose (2b), and the combination of a strategic intramolecular cyclopropanation step plus the acid-catalyzed isomerization of an isopropylidene group, provided a suitable pseudosugar precursor (23) for the synthesis of MRS1898, MRS2346, and related analogues. This new synthetic route uses readily available building blocks and opens the way for the preparation of a variety of targets on a reasonable scale.     

Electrorheological behavior of suspensions of a substituted polyaniline with long alkyl pendants

The electrorheological (ER) properties of poly(2-dodecyloxyaniline) (PDOA) suspensions in silicone oil were investigated. The ER behavior of such suspensions of polyaniline particles depends on the type of stabilizer and doping or dedoping level. Here we report on the ER behavior of particles of a substituted polyaniline with long alkyl pendants. Rheological measurements were carried out using a rotational rheometer with high-voltage generator in both constant shear stress and rate modes. Suspensions of the as-synthesized polyaniline particles in silicone oil showed a substantial ER response.     

Solid-state structure and condensation reaction of (triphenylmethyl)silanetriol

(Triphenylmethyl)silanetriol [1, (Ph₃C)Si(OH)₃] was obtained in 98% yield by the hydrolysis of (triphenylmethyl)trichlorosilane with ice-water in diethyl ether. Single crystal of [1 · acetone] for X-ray crystallographic determination was grown from a saturated acetone solution. In the single crystal X-ray structure analysis, the silanetriol 1 crystallizes in the centrosymmetric triclinic space group with two independent molecules in the asymmetric unit. Two independent molecules of the silanetriols 1 interact with each other and with acetones by intermolecular hydrogen bondings. Such hydrogen-bonding interactions lead to a one-dimensional columnar polymeric tube. Finally, this tube interacts with others to make sheets alternating hydrophobic organic part and hydrophilic hydroxy groups of the molecules 1 and the oxygen of acetones arranged regularly. The silanetriol 1 is very stable compound in solution and in solid states at room temperature, but decomposed in the presence of KOH, and undergoes a condensation reaction with dicyclohexylcarbodiimide (DCC) as strong dehydrating agent to give polysiloxane. The silanetriol 1 reacts with trimethylchlorosilane to give three type siloxane products (Ph₃C)Si(OH)_3−n(OSiMe₃)_n (n = 1, 2, 3). The number (n) of silylation of hydroxy groups on the silanetriol 1 increase with increasing the mol ratio of trimethylchlorosilane used.     

Macrocyclic lactam synthesis via a ring expansion reaction: construction of the cripowellin skeleton

[reaction: see text] The cripowellin ring skeleton, a macrocyclic [2.3.5]-bicyclic ketolactam, was smoothly generated via construction of a spiro(benzazepin-cyclohexane-1,3-dione) employing oxidative cyclization as a key step and a subsequent ring expansion reaction.