Search results for "Tetra"

Production of dibutyl carbonate by insertion of CO2 in titanium(IV) tetrabutoxide

2015

The species resulting from insertion of 12CO2 and 13CO2 into titanium(IV) butoxide is for the first time fully characterized by means of infrared and nuclear magnetic resonance spectroscopy. Results show formation of Ti-monobutylcarbonate, that easily undergoes nucleophilic attack by an aliphatic amine. The hydrolysis of the resulting species produces butylcarbamate and dibutylcarbonate as the only main products. Characterization results of the carbonate-like adduct, along with its reactivity with amine molecules open the route to new ways of CO2 utilization as building block for valuable organic compounds.

CVG-ICP-OES -menetelmän käyttö elohopean analysointiin eläinkudoksesta

2015

Tässä Pro gradu –tutkielmassa käsitellään elohopean määritystä eläinkudoksesta kemiallinen höyryn muodostus induktiivisesti kytketty plasma optinen emissio spektrometria –menetelmällä (CVG-ICP-OES) ja siihen liittyvää näytteenkäsittelyä. Tutkimuksen kirjallisessa osassa käydään läpi muun muassa eri näytteenliuotusmenetelmiä, analyysimenetelmiä, tutkittavien metallien pelkistämistä CVG-ICP-OES –analyysiä varten ja CVG-ICP-OES –analyysissä esiintyviä häiriöitä. Näytteenliuotusosassa keskitytään pääasiassa tutkimuksessa käytetyn ultraäänihajotuksen esittelyyn, tämän lisäksi myös muita yleisiä näytteenliuotusmenetelmiä esitetään. Analyysimenetelmä osiossa suurin huomio keskittyy ICP-OES –laitte…

Hepatic responses of gene expression in juvenile brown trout (Salmo trutta lacustris) exposed to three model contaminants applied singly and in combi…

2007

Chemical pollution of the aquatic environment is almost always the result of multiple rather than single toxic compounds. The possibility of separating the effects of key risk chemicals from those of others, including their joint effects, is of clear theoretical interest and high technical importance. We addressed this goal using multiple gene expression profiling in the liver of juvenile brown trout (Salmo trutta lacustris) exposed to three model chemicals (cadmium, carbon tetrachloride [CCl4], and pyrene) administered singly, in binary and trinary combinations at low acutely sublethal concentrations, and in the partial dose–response manner. Differentially expressed genes were grouped by c…

Lower rim arylation of calix[n]arenes with extended perfluorinated domains

2006

Abstract Exhaustive O-arylation of p-tert -butylcalix[ n ]arenes 2 ( n  = 4–8) with an excess of 3-pentadecafluoroheptyl-5-pentafluorophenyl-1,2,4-oxadiazole 3 and K 2 CO 3 in refluxing acetonitrile provides an easy entry to a new family of perfluorinated calix[ n ]arenes 1 . The cyclic tetramer furnishes a mixture of cone , partial cone , and 1,2-alternate conformers, while the larger macrocycles afford single products. The structures of all new compounds are substantiated by NMR techniques and MALDI-TOF mass spectral data. Single-crystal X-ray diffraction studies on the pentamer derivative 1b reveal a distorted cone-in conformation of the calixarene cup.

TCDD deregulates contact inhibition in rat liver oval cells via Ah receptor, JunD and cyclin A.

2007

The aryl hydrocarbon receptor (AhR) is a transcription factor involved in physiological processes, but also mediates most, if not all, toxic responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Activation of the AhR by TCDD leads to its dimerization with aryl hydrocarbon nuclear translocator (ARNT) and transcriptional activation of several phase I and II metabolizing enzymes. However, this classical signalling pathway so far failed to explain the pleiotropic hazardous effects of TCDD, such as developmental toxicity and tumour promotion. Thus, there is an urgent need to define genetic programmes orchestrated by AhR to unravel its role in physiology and toxicology. Here we show that TCDD …

P105. New findings on vasodilator potency, tachyphylaxis, and bioavailability of organic nitrates reveal: The tolerance-devoid clinical action of pen…

2006

Bovine seminal ribonuclease is cytotoxic for both malignant and normal telomerase-positive cells

2005

Bovine seminal-ribonuclease (BS-RNase) is a member of the 'ribonucleases with special biological actions' family since it possesses specific anti-tumour, anti-spermatogenic and embryotoxic activities and exerts an immunosuppressive effect on T lymphocytes. In previous studies it was demonstrated that BS-RNase induced apoptosis in proliferating, malignant and normal cells and that telomerase activity loss also caused apoptotic death in neoplastic cells. Since an obvious relationship between cell proliferation and telomerase activity exists, the aim of this work was to study if the pro-apoptotic cytotoxic action exerted by BS-RNase on proliferating malignant cells (HT29) and proliferating nor…

Involvement of protein kinase Cdelta in contact-dependent inhibition of growth in human and murine fibroblasts.

2001

There is evidence that protein kinase C delta (PKCdelta) is a tumor suppressor, although its physiological role has not been elucidated so far. Since important anti-proliferative signals are mediated by cell-cell contacts we studied whether PKCdelta is involved in contact-dependent inhibition of growth in human (FH109) and murine (NIH3T3) fibroblasts. Cell-cell contacts were imitated by the addition of glutardialdehyde-fixed cells to sparsely seeded fibroblasts. Downregulation of the PKC isoforms alpha, delta, epsilon, and mu after prolonged treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA, 0.1 microM) resulted in a significant release from contact-inhibition in FH109 cells. Bryosta…

Reduction of glutathione content by 12-O-tetradecanoylphorbol-13-acetate in confluent, but not in sparse cultures of human diploid fibroblasts.

1990

Treatment of confluent cultures of human diploid fibroblasts with 12-O-tetradecanoylphorbol-13-acetate (TPA) (10(-7) M) resulted in a 70% reduction of the glutathione (GSH) content, compared with untreated controls. The effect, which was dose-dependent, was observed 8 h after the beginning of the treatment could be followed for up to 72 h. On the other hand, GSH reduction was specific for confluent cultures, as the level of glutathione remained unchanged by TPA treatment of sparse cultures. The addition of immobilized plasma membrane proteins to sparsely seeded cells has been shown previously to induce cellular reactions which are characteristic for confluent cultures. It was shown that TPA…

Extensive phytocannabinoid profiles of seized cannabis and cannabis-based medicines – Identification of potential distinguishing markers

2021

As the frequency of cannabis-based therapy increases, the ability to distinguish intake of cannabis-based medicines from recreational cannabis use becomes desirable. Minor cannabinoids have been suggested to indicate recreational cannabis use in biological matrices but are unreliable when presumably also present in directly plantderived medicines. Thus, for therapeutics such as medical cannabis, Sativex® and Dronabinol, a more thorough investigation of cannabinoid profiles is required to identify possible distinguishing markers. In this study, 16 phytocannabinoids were quantified in samples of seized and medical cannabis, Sativex® and Dronabinol from two different manufacturers, using a val…