The dimerization of 1-alkynes by rhodium(I) catalysts. Effect of phosphorus ligands on regioselectivity

The dimerization of 1-alkynes by rhodium(I) complexes in the presence of phosphorus ligands is described. The products are linear and branched dimers, the ratio of which is correlated with the electronic parameters, v_CO of Ni(CO)₃L, of the ligands L, but no simple correlation is apparent between their steric parameter and the selectivity. Electron-donating ligands promote the formation of the linear dimer. The substituents of the 1-alkynes also affect the distribution of linear and branched dimers. Electron-donating substituents prefer linear isomer to branched one. The reactivity of the substituted 1-alkynes (R? C?C? H) increased with substituent R in the order      

Dimerization and polymerization of butadiene with zero-valent nickel and protonic acids

The behavior of hydridonickel coordination compounds as catalysts for the oligomerization and polymerization of butadiene in various solvents was studied. In the presence of alcohol bis(tricyclohexylphosphine)chlorohydridonickel ( 4 , X = Cl) (HNiCl[P(C₆H₁₁)₃]₂) catalyzes the linear dimerization. With hydridotetrakis(phosphite)nickel(1+) ( 2 ) ([HNi{P(OR)₃}₄]⁺), which is prepared from tetrakis(phosphite)nickel ( 1 ) (Ni[P(OR)₃]₄) and trifluoroacetic acid, dimerization occurs in sec-alcohol but there is no reaction in tert-alcohol. The main product is 2-methylenevinylcyclopentane ( 8 ). The other products are 4-vinylcyclohexene ( 10 ), 1,5-cyclooctadiene ( 5 ), 1,3,7-octatriene ( 7 ) and 1,3,6-octatriene ( 9 ). The hydridonickel coordination compound, prepared with inorganic acids, does not afford the dimers but the 1,4-trans polymer.     

Transforming growth factor-beta stimulates interleukin-11 production by human periodontal ligament and gingival fibroblasts

BACKGROUND: Transforming growth factor (TGF)-beta is a potent multifunctional polypeptide, abundant in the bone matrix. Interleukin (IL)-11 is a pleiotropic cytokine with effects on multiple cell types. The present study was performed to evaluate the regulatory effects of TGF-beta on IL-11 production by human periodontal ligament cells (PDL) and human gingival fibroblasts (HGF). MATERIAL AND METHODS: The expression of TGF-beta receptor in PDL and HGF were observed using flow cytometry. PDL and HGF were stimulated with TGF-beta with or without protein kinase C (PKC) inhibitors and activator. IL-11, bone morphogenetic protein-2 (BMP-2) and TGF-beta mRNA expression was quantified by real-time polymerase chain reaction (PCR). IL-11 production was measured using enzyme-linked immunosorbent assay. RESULTS: PDL and HGF expressed both TGF-beta receptor I and TGF-beta receptor II on the cell surfaces. IL-11 mRNA expression and IL-11 production were augmented by TGF-beta in both PDL and HGF, with higher values in PDL. PKC inhibitors partially suppressed TGF-beta-induced IL-11 production in PDL and HGF, whereas activator enhanced it. TGF-beta mRNA and BMP-2 mRNA expression were up-regulated by TGF-beta in PDL. CONCLUSION: These results suggest that PDL produce IL-11 in response to TGF-beta.     

Off-pump coronary artery bypass grafting via a left thoracotomy in a patient with left main trunk disease

We report a case of multiple coronary artery bypass grafting (CABG) via a left thoracotomy without cardiopulmonary bypass. A 54-year-old female with unstable angina pectoris associated with left main trunk disease underwent emergency CABG. Because the patient had a history of total arch and aortic root replacement due to type A aortic dissection, a left thoracotomy approach was selected. The proximal end of the Y-shaped saphenous vein graft was anastomosed to the left subclavian artery, rather than to the descending aorta, owing to the remaining aortic dissection. The distal end of the Y-shaped saphenous vein graft was anastomosed to the left anterior descending artery and the posterolateral branch without cardiopulmonary bypass. The postoperative course was uneventful. The results of this surgery seem to indicate that off-pump CABG via a left thoracotomy is a viable technique, especially for patients undergoing repeat CABG.     

LPS-stimulated human gingival fibroblasts inhibit the differentiation of monocytes into osteoclasts through the production of osteoprotegerin

Periodontitis is an inflammatory bone disease caused by Gram-negative anaerobic bacteria, but the precise mechanism of bone destruction remains unknown. Activated T lymphocytes secrete receptor activator of NF-kappaB ligand (RANKL) and support the differentiation of monocytes into mature osteoclasts. The purpose of this study was to examine the expression of RANKL and its inhibitor, osteoprotegerin (OPG), in inflamed gingival tissue and to clarify the role of human gingival fibroblasts (HGFs) in osteoclastogenesis regulated by RANKL. HGFs and gingival mononuclear cells (GMCs) were obtained from chronic periodontitis patients during routine periodontal surgery. Expression of OPG and RANKL mRNA in gingival tissue and HGFs was examined with RT-PCR. OPG production was measured using ELISA. Expression of RANKL, CD4, CD8 and CD69 on GMCs was determined by flow-cytometry using RANK-Fc fusion protein and the respective monoclonal antibodies. Osteoclastogenesis by RANKL was assayed by counting the number of tartarate-resistant acid phosphatase (TRAP)-positive cells after culturing human peripheral blood monocytes with recombinant human RANKL and macrophage-colony stimulating factor (M-CSF) for 10 days. OPG and RANKL mRNA were expressed in 80% (16/20) and 25% (5/20) of periodontitis lesions, respectively. OPG, but not RANKL, mRNA was expressed within HGFs. OPG mRNA expression and production by HGFs was augmented by LPS stimulation. All GMC samples expressed CD69, and two of five GMC samples expressed RANKL. The culture supernatant of LPS-stimulated gingival fibroblasts significantly reduced the number of TRAP positive cells generated by culturing monocytes with RANKL and M-CSF. The present study suggests that LPS-stimulated HGFs inhibit monocyte differentiation into osteoclasts through the production of OPG.     

Aortic valve replacement using Medtronic Freestyle stentless porcine xenograft

We analyzed the left ventricular hemodynamic changes after aortic valve replacement using Medtronic Freestyle stentless valve. Doppler echocardiograms were performed at three weeks and three months after operation in twelve patients. Both left ventricular end-diastolic volume (index) and left ventricular end-systolic volume (index) were decreased respectively. Fractional shortening were markedly increased from 21.4 +/- 7% to 31.8 +/- 3.8%, and left ventricular mass index were markedly decreased from 194.3 +/- 25.3 g/m2 to 182.3 +/- 24.4 g/m2. Transvalvular pressure gradient measured by cardiac catheterization were almost zero mmHg at three weeks after operation. No aortic regurgitation were found in all cases. Good left ventricular remodeling were obtained so that we believe this valve could be acceptable alternative for many surgeons. These excellent results justify wider use of stentless valve.