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An alternative method for the synthesis of brevetoxin B uses the heptacyclic phosphonium iodide and the tricyclic aldehyde as the basic materials for the brevetoxin B framework. The production of the tricyclic lactone and the dioxepane region of the molecule are carried out by Yamaguchi lactonization. Murai coupling which involves the addition of a higher order organocuprate to the lactone-derived enol triflate attaches the essential appendage on ring E. Fetizon cyclization produces the pentacyclic lactone while Cr/Ni coupling reaction produces allylic alcohol as a precursor to the pentacyclic lactol.

We studied the emission properties of colloidal PbS quantum dots (QDs) (5.3 nm) dispersed on semi-insulating GaAs in the temperature range of 5–300 K by employing Fourier transform infrared photoluminescence spectroscopy. The results reveal that the PbS QDs alter and notably enhance the emission features of the GaAs substrate itself. The dependence of the QD emission peak position on temperature is modeled equivalently well with the well-known empirical Varshni equation and with a relation based on thermodynamics. The work reveals that emission properties of PbS QDs do not follow predictably general rules but are determined sensitively by the preparation method and substrate used. [ABSTRACT FROM AUTHOR]

Objective: To investigate the therapeutic effect and mechanism of sodium tanshinone IIA sulfate (STS) on paraquat (PQ)-induced myocardial injuries in a rat model. Methods: Healthy adult Sprague Dawley rats were randomly divided into normal control, PQ, and PQ + STS groups. PQ group was given a single intragastric administration of PQ (80 mg/kg). PQ + STS group was intraperitoneally injected with STS (1 ml/kg) at 30 min following PQ exposure. Rats in control and PQ groups were injected with equal amount of saline. After 12, 24, 48, and 72 h, rats were killed, and the apoptosis of myocardial cells was detected. Myocardial expression of Bax and Bcl-2 was measured. The activity of the nuclear erythroid 2-related factor 2 (Nrf2) pathway was assessed by Western blot. Results: The apoptotic cells in PQ group were significantly increased in a time-dependent manner compared with the control group (p < 0.01). The rats in PQ group exhibited significantly lower Bcl-2 expression, but notably higher Bax expression at 12, 24, 48, and 72 h after PQ exposure (p < 0.05 or 0.01). STS intervention markedly reduced the proportion of apoptotic myocardial cells, increased Bcl-2 expression, and decreased Bax expression at 24, 48, and 72 h after treatment (p < 0.05 or 0.01). The expression of phosphorylated Nrf2 and heme oxygenase 1 in PQ + STS group was significantly increased compared with PQ and control groups (p < 0.05 or 0.01). Conclusion: STS effectively inhibits PQ-induced myocardial cell apoptosis in rats via modulating the Nrf2 pathway, suggesting its potential as a promising therapeutic agent for PQ-induced myocardium damage. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Yes-associated protein (YAP) is a critical factor of Hippo pathway. It can control organ size, regulate proliferation, differentiation, and apoptosis of cells, and mediate epithelial- mesenchymal transition and cell contact inhibition. It has gradually become a hot spot in the field of diabetic nephropathy (DN). Tea domain (TEAD) is a factor with a deoxyribose nucleic acid (DNA) binding domain, which combines with activated YAP to control the expression of their important target factor - connective tissue growth factor (CTGF). PATIENTS AND METHODS: We have investigated the role of YAP in type 2 diabetic nephropathy and evaluated the correlation between YAP and the progress of type 2 diabetic nephropathy. We have detected the expression of YAP, TEAD and CTGF in normal people (n=10) and patients with DN (n=51) by immunohistochemical and immunofluorescence staining and evaluated the relationship among clinical, pathologic data and YAP expression in type 2 diabetic nephropathy. RESULTS: In kidneys of type 2 diabetic nephropathy, YAP, TEAD and CTGF were highly expressed in the nucleus of glomerular podocytes. In those healthy kidneys, however, all three of the above factors were mainly expressed in cytoplasm. Furthermore, the high expression of YAP in DN had relevance to increasing systolic blood pressure (SBP) (r=0.484, p=0.019), blood urea nitrogen (BUN) (r=0.522, p=0.032), creatinine (Cr) (r=0.496, p=0.031), progression of DN stage (r=0.647, p=0.001) and progression of DN pathologic classification (r=0.298, p=0.033). In addition, decreasing serum albumin (SAlb) (r=- 0.656, p=0.001) and estimated glomerular filtration rate (eGFR) (r=-0.607, p=0.006) were also correlated with the high expression of YAP in DN. CONCLUSIONS: High expression of YAP, TEAD and CTGF in kidney tissues suggested that YAP played a significant role in the renal damage of type 2 diabetic nephropathy. YAP that is correlated with SBP, BUN, Cr, DN stage, DN pathologic classification, SAlb and eGFR, suggested that inhibition of the activity of YAP might have the effect in delaying DN progression. [ABSTRACT FROM AUTHOR]

OBJECTIVE: In liver transplantation, long-time portal vein blocking causes the occurrence of ischemic liver injury. Dexmedetomidine, a widely admired anesthetic, has been reported as a protective agent on organs under ischemic condition. The objective of this study was to reveal the role and underlying mechanism of dexmedetomidine in ischemic liver injury. MATERIALS AND METHODS: L-02 cells were treated with dexmedetomidine during 6 h of oxygen- glucose deprivation (OGD) exposure. The expression of microRNA-711 (miR-711) in cell was overexpressed by miRNA transfection. Then, the following parameters were observed: cell viability, apoptosis, the expression of apoptosis- related proteins, and the expression and the release of Interleukin 1 beta (IL-1β) and Tumor necrosis factor alpha (TNF-α). RESULTS: Apoptosis and inflammation were induced following OGD exposure in L-02 cells, as cell viability was impaired, apoptotic cell rate was increased, caspase-3, and caspase-9 was cleaved, and the expression and release of TNF-α and IL-1β were increased. Dexmedetomidine attenuated OGD-induced apoptosis and inflammation, and dexmedetomidine down-regulated the expression of miR-711. Also, dexmedetomidine blocked the activation of p38 mitogen-activated protein kinase (p38MAPK) and Janus kinase (JAK)/signal transducer and activator of transcription protein (STAT) signaling upon OGD. Moreover, when miR-711 was overexpressed, dexmedetomidine did not protect L-02 cells against OGD, and did not block p38MAPK and JAK/STAT signaling pathways. CONCLUSIONS: Dexmedetomidine ameliorated OGD-induced cell apoptosis and inflammation in L-02 cells, exerting protective activities in ischemic liver injury. The anti-OGD effects of dexmedetomidine might be realized by down-regulation of miR-711 and suppression of p38MAPK and JAK/STAT signaling pathways. [ABSTRACT FROM AUTHOR]

A new synthetic procedure uses a previously prepared intermediate to construct the CDEFG framework of brevetoxin B. Methods used for the design of oxocene and tetrahydropyran units help plan the synthetic strategy. The strategy involves various steps including Swern oxidation, hydrogenation, lactonizations and coupling steps. X-ray crystallography helps determine the structure of a lactone formed during the synthesis.

Research on the influence of alloy concentration and distribution on bimetallic cluster plays a key role in exploring new structural material. This paper studies the melting process of icosahedral bimetallic cluster (PdPt)147 with different Pt concentrations and different atomic distributions by using molecular dynamics with an embedded atom method. The results indicate that the mixed Pd-Pt cluster shows an irregular phenomenon between 580 and 630 K, i.e. the atomic energy decreases with the increase of temperature. This is because the surface energy of Pd is lower than that of Pt; the decreased energy due to Pd atomic segregation is larger than the increased energy due to heating during the segregation process. In addition, the temperature of Pd atomic segregation is strongly related to Pt concentration. This leads to that Pd atoms prefer to remain on the surface even after the cluster melted. [ABSTRACT FROM AUTHOR]