Search results for "proline"
showing 10 items of 183 documents
ChemInform Abstract: Hydrophobically Directed Aldol Reactions: Polystyrene-Supported L-Proline as a Recyclable Catalyst for Direct Asymmetric Aldol R…
2008
A simple synthetic methodology for the preparation of a polystyrene-supported L-proline material is reported, and this material has been used as catalyst in direct asymmetric aldol reactions between several ketones and arylaldehydes to furnish aldol products in high yields and stereoselectivities. Screening of solvents showed that these reactions take place only in the presence of water or methanol, at lower levels of conversion in the latter case. This solvent effect, coupled with the observed high stereoselectivities, has been explained in terms of the formation of a hydrophobic core in the inner surface of the resin, whereas the hydrophilic proline moiety lies at the resin/water interfac…
Myo-inositol as a main metabolite in overwintering flies: seasonal metabolomic profiles and cold stress tolerance in a northern drosophilid fly
2012
SUMMARY Coping with seasonal changes in temperature is an important factor underlying the ability of insects to survive over the harsh winter conditions in the northern temperate zone, and only a few drosophilids have been able to colonize sub-polar habitats. Information on their winter physiology is needed as it may shed light on the adaptive mechanisms of overwintering when compared with abundant data on the thermal physiology of more southern species, such as Drosophila melanogaster. Here we report the first seasonal metabolite analysis in a Drosophila species. We traced changes in the cold tolerance and metabolomic profiles in adult Drosophila montana flies that were exposed to thermope…
Role of reactive oxygen species in the regulation of HIF-1 by prolyl hydroxylase 2 under mild hypoxia
2012
The function and survival of eukaryotic cells depends on a constant and sufficient oxygen supply. Cells recognize and respond to hypoxia by accumulation of the transcription factor hypoxia-inducible factor 1 (HIF-1), composed of an oxygen-sensitive HIF-1α and a constitutive HIF-1β subunit. Besides physiology, HIF-1 induction is involved in major pathological processes such as cardiovascular disease, inflammation and cancer, which are associated with the formation of reactive oxygen species (ROS). ROS have been reported to affect HIF-1 activity but the role for ROS in regulating HIF-1 has not been definitely settled. In order to shed light on the redox-regulation of HIF-1 by ROS, we studied …
On the enhancement of stereoselection by cooperation between chiral auxiliaries. Asymmetric diels-alder reactions with fumaric acid bis ((S)-proline …
1989
Abstract Fumaric acid bis ((S)-proline benzyl ester) amide reacts with cyclopentadiene in thermal and Lewis acid catalyzed Diels-Alder reactions to give the cycloadducts with high yields and diastereomeric ratios up to 100:1.
Regulatory cytokine gene polymorphisms and risk of colorectal carcinoma.
2006
It is well established that cancer arises in chronically inflamed tissue, and this is particularly notable in the gastrointestinal tract. Classic examples include Helicobacter pylori-associated gastric cancer, hepatocellular carcinoma, and inflammatory bowel disease-associated colorectal cancer. Growing evidence suggests that these associations might be not casual findings. Focusing on individual cytokines has generated evidence that anti-inflammatory cytokine interleukin (IL)-10 and transforming growth factor-beta1 (TGF-beta1) may have a complex role in gastrointestinal carcinogenesis. As an example, IL-10-deficient mice develop severe atrophic gastritis and a chronic enterocolitis, develo…
Anemia during treatment with peginterferon Alfa-2b/ribavirin and boceprevir: Analysis from the serine protease inhibitor therapy 2 (SPRINT-2) trial
2013
International audience; Boceprevir (BOC) added to peginterferon alfa-2b (PegIFN) and ribavirin (RBV) significantly increases sustained virologic response (SVR) rates over PegIFN/RBV alone in previously untreated adults with chronic hepatitis C genotype 1. We evaluate the relationship of incident anemia with triple therapy. A total of 1,097 patients received a 4-week lead-in of PegIFN/RBV followed by: (1) placebo plus PegIFN/RBV for 44 weeks (PR48); (2) BOC plus PegIFN/RBV using response-guided therapy (BOC/RGT); and (3) BOC plus PegIFN/RBV for 44 weeks (BOC/PR48). The management of anemia (hemoglobin [Hb]<10 g/dL) included RBV dose reduction and/or erythropoietin (EPO) use. A total of 1,080…
Loss of PHD3 allows tumours to overcome hypoxic growth inhibition and sustain proliferation through EGFR
2014
Solid tumours are exposed to microenvironmental factors such as hypoxia that normally inhibit cell growth. However, tumour cells are capable of counteracting these signals through mechanisms that are largely unknown. Here we show that the prolyl hydroxylase PHD3 restrains tumour growth in response to microenvironmental cues through the control of EGFR. PHD3 silencing in human gliomas or genetic deletion in a murine high-grade astrocytoma model markedly promotes tumour growth and the ability of tumours to continue growing under unfavourable conditions. The growth-suppressive function of PHD3 is independent of the established PHD3 targets HIF and NF-κB and its hydroxylase activity. Instead, l…
Different conformations of nascent polypeptides during translocation across the ER membrane
2000
Abstract Background In eukaryotic cells, proteins are translocated across the ER membrane through a continuous ribosome-translocon channel. It is unclear to what extent proteins can fold already within the ribosome-translocon channel, and previous studies suggest that only a limited degree of folding (such as the formation of isolated α-helices) may be possible within the ribosome. Results We have previously shown that the conformation of nascent polypeptide chains in transit through the ribosome-translocon complex can be probed by measuring the number of residues required to span the distance between the ribosomal P-site and the lumenally disposed active site of the oligosaccharyl transfer…
Increased activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase, enzymes of collagen biosynthesis, in skeletal muscle of …
1983
The activities of prolyl 4-hydroxylase (PH) and galactosylhydroxylysyl glucosyltransferase (GGT), and the concentration of 4-hydroxyproline were measured in red and white parts of quadriceps femoris muscle of mice after 3, 10, and 20 sessions of daily endurance training. The activities of PH and GGT increased in the red part of the muscle after training for 3 and 10 times and returned to the control level after 20 training sessions. In the white muscle the increase of PH activity was less than in the red muscle. No alteration in GGT activity was observed in the white muscle. The concentration of hydroxyproline was unchanged in the both types of skeletal muscle. The results suggest that coll…
Using NMR in saliva to identify possible biomarkers of glioblastoma and chronic periodontitis
2018
Nowadays there is increasing interest in identifying-and using-metabolites that can be employed as biomarkers for diagnosing, treating and monitoring diseases. Saliva and NMR have been widely used for this purpose as they are fast and inexpensive methods. This case-control study aimed to find biomarkers that could be related to glioblastoma (GBL) and periodontal disease (PD) and studied a possible association between GBL and periodontal status. The participants numbered 130, of whom 10 were diagnosed with GBL and were assigned to the cases group, while the remaining 120 did not present any pathology and were assigned to the control group. On one hand, significantly increased (p < 0.05) meta…