Search

Thermal treatment of the trinuclear ruthenium complex {μ2-η5:η¹-(C5H4N)(C9H5)}Ru3(CO)9 (1) with 1,5-heptadiene, diallyl sulfide, 1,4-hexadiene, and 1,7-octadiene respectively generated the series of diruthenium products {(C5H4N)(μ2-η5,η¹-C9H5CHCH2CH2R)}Ru2(CO)x (4, R = -CH2CH CHCH3; 6, R = SCH2CH CH2; 7, R = -CH CHCH3; 8, R = -(CH2)3CH CH2) via the insertion of an terminal C C bond into the Ru-C(η¹) bond of 1. When 1 was treated with diallyl ether, the complex {(C5H4N)(μ2-η5,η³-C9H5CCH2CH2OCCHCH3)}Ru2(CO)4 (5) with a five-membered oxygen-containing heterocycle was produced. Reactions of 2-methyl-3-(2-pyridyl)indene or 2,5-dimethyl-3-(2-pyridyl)indene with Ru3(CO)12 gave the cycloruthenated complexes {(C5H4N)(μ2-η5,η¹-RC9H4CH2)}Ru2(CO)5 (9, R = H; 10, R = CH3) with structures similar to those of 4, 7, and 8, via C(sp³)-H activation. The molecular structures of 5-7 and 10 were determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Examines the photovoltaic effect of interband transitions in silicon germanium/silicon multiple quantum wells. Evidence for transitions between hole and electron subbands; Formation of defects from partial relaxation of the misfit strain in the quantum wells; Characteristics of photovoltaic structures related to interband transitions.

A combined experimental and computational investigation of the CO dissociation properties of three [Fe]-hydrogenase models, [(2-CH2CO-6-HOC5H3N)Fe(CO)3I] (1), [(2-CH2CO-6-MeOC5H3N)Fe(CO)3I] (2), and [(2-CH2CO-6-t-BuOC5H3N)Fe(CO)3I] (3), shows equilibria of tricarbonyl and dicarbonyl complexes in solution. In CH3CN, 1 transforms to the solvated product [(2-CH2CO-6-HOC5H3N)Fe(CO)2(CH3CN)I] (7). The reactivity of 2 with PPh3 was also explored, giving [(2-CH2CO-6-MeOC5H3N)Fe(CO)2(PPh3)I] (8) via one CO substitution by PPh3. [ABSTRACT FROM AUTHOR]

Lipolysis is a critical metabolic pathway contributing to energy homeostasis through degradation of triacylglycerides stored in lipid droplets (LDs), releasing fatty acids. Neutral lipid lipases act at the oil/water interface. In mammalian cells, LD surfaces are coated with one or more members of the perilipin protein family, which serve important functions in regulating lipolysis. We investigated mechanisms by which three perilipin proteins control lipolysis by adipocyte triglyceride lipase (ATGL), a key lipase in adipocytes and non-adipose cells. Using a cell culture model, we examined interactions of ATGL and its co-lipase CGI-58 with perilipin 1 (perilipin A), perilipin 2 (adipose differentiation-related protein), and perilipin 5 (LSDP5) using multiple techniques as follows: anisotropy Forster resonance energy transfer, co-immunoprecipitation, [32P]orthophosphate radiolabeling, and measurement of lipolysis. The results show that ATGL interacts with CGI-58 and perilipin 5; the latter is selectively expressed in oxidative tissues. Both proteins independently recruited ATGL to the LD surface, but with opposite effects; interaction of ATGL with CGI-58 increased lipolysis, whereas interaction of ATGL with perilipin 5 decreased lipolysis. In contrast, neither perilipin 1 nor 2 interacted directly with ATGL. Activation of protein kinase A (PKA) increased [32P]orthophosphate incorporation into perilipin 5 by 2-fold, whereas neither ATGL nor CGI-58 was labeled under the incubation conditions. Cells expressing both ectopic perilipin 5 and ATGL showed a 3-fold increase in lipolysis following activation of PKA. Our studies establish perilipin 5 as a novel ATGL partner and provide evidence that the protein composition of perilipins at the LD surface regulates lipolytic activity of ATGL. [ABSTRACT FROM AUTHOR]

Lipolysis is an important metabolic pathway controlling energy homeostasis through degradation of triglycerides stored in lipid droplets and release of fatty acids. Lipid droplets of mammalian cells are coated with one or more members of the PAT protein family, which serve important functions in regulating lipolysis. In this study, we investigate the mechanisms by which PAT family members, perilipin A, adipose differentiation-related protein (ADFP), and LSDP5, control lipolysis catalyzed by hormone-sensitive lipase (HSL), a major lipase in adipocytes and several non-adipose cells. We applied fluorescence microscopic tools to analyze proteins in situ in cultured Chinese hamster ovary cells using fluorescence recovery after photobleaching and anisotropy Forster resonance energy transfer. Fluorescence recovery after photobleaching data show that ADFP and LSDP5 exchange between lipid droplet and cytoplasmic pools, whereas perilipin A does not. Differences in protein mobility do not correlate with PAT protein-mediated control of lipolysis catalyzed by HSL or endogenous lipases. Forster resonance energy transfer and co-immunoprecipitation experiments reveal that each of the three PAT proteins bind HSL through interaction of the lipase with amino acids within the highly conserved amino-terminal PAT-1 domain. ADFP and LSDP5 bind HSL under basal conditions, whereas phosphorylation of serine residues within three amino-terminal protein [ABSTRACT FROM AUTHOR]

Obesity is strongly associated with insulin resistance, type 2 diabetes, cardiovascular diseases and dyslipidemia. How these seemingly distinctive diseases cluster together as the metabolic syndrome is a scientifically intriguing and clinically important question, but not well understood. Recent studies indicate that chronic systemic inflammation may be a cause behind the syndrome and that the adipose tissue may contribute to the inflammation since it is not only a storage depot for excess fat, but also is an endocrine organ secreting many polypeptides, known as adipokines. Dysregulation of adipokines may be responsible for the elevation of the inflammatory state in obesity and obesity-associated comorbidities. Numerous studies have investigated the change of adipokines in obesity and diabetes conditions, but the data from Chinese patients are very limited. In this study, we measured the serum levels of several representative adipokines in obese and diabetic Chinese patients treated with rosiglitazone. In non-diabetic subjects, the serum levels of serum amyloid A (SAA), C-reactive protein (CRP) and TNFa in obese people (BMI ≥ 24, n = 24) was significantly higher than the lean subjects (BMI < 24, n = 26, p < 0.01). In contrast, adiponectin levels were significantly lower in the obese group (p < 0.01). On the other hand, no difference in IL-6 and resistin levels was found between the lean and obese groups. Moreover, these adipokines were measured in 34 impaired glucose regulation (IGR) patients and 44 new-onset type 2 diabetes patients (T2D) patients before and after the treatment with rosiglitazone at 4 mg/day for 12 weeks. The rosiglitazone did not change BMI in both groups but decreased fasting glucose and HbA1c levels in the T2D group. The treatment reduced CRP, TNFa and SAA by 11-39% and increased adiponectin by 82% with statistical significance. In conclusion, we found that inflammatory adipokines were elevated in obesity and decreased in diabetics after rosiglitazone treatment, supporting that adipokines may be a mediator in the metabolic syndrome. [ABSTRACT FROM AUTHOR]