The identification of small molecule ligands for the peroxisome proliferator-activated receptors (PPARs) has been instrumental in elucidating their biological roles. In particular, agonists have been ...the focus of much of the research in the field with relatively few antagonists being described and all of those being selective for PPARα or PPARγ. The comparison of these agonist and antagonist ligands in cellular and animal systems has often led to surprising results and new insights into the biology of the PPARs. The PPARβ/δ receptor is emerging as an important regulator of energy metabolism, inflammation, and cell growth and differentiation; however, only agonist ligands have been described for this receptor thus far. Here we describe the first report of a PPARβ/δ small molecule antagonist ligand. This antagonist ligand will be a useful tool for elucidating the biological roles of PPARβ/δ.
The peroxisome proliferator activated receptors PPARα, PPARγ, and PPARδ are ligand-activated transcription factors that play a key role in lipid homeostasis. The fibrates raise circulating levels of ...high-density lipoprotein cholesterol and lower levels of triglycerides in part through their activity as PPARα agonists; however, the low potency and restricted selectivity of the fibrates may limit their efficacy, and it would be desirable to develop more potent and selective PPARα agonists. Modification of the selective PPARδ agonist 1 (GW501516) so as to incorporate the 2-aryl-2-methylpropionic acid group of the fibrates led to a marked shift in potency and selectivity toward PPARα agonism. Optimization of the series gave 25a, which shows EC50 = 4 nM on PPARα and at least 500-fold selectivity versus PPARδ and PPARγ. Compound 25a (GW590735) has been progressed to clinical trials for the treatment of diseases of lipid imbalance.
Cholesteryl ester transfer protein (CETP) plays a key role in high-density lipoprotein (HDL) cholesterol metabolism, but normal mice are deficient in CETP. In this study, transgenic mice expressing ...both human apolipoprotein B 100 (ApoB-100) and human CETP (hApoB100/hCETP) were used to characterize the effects of CETP inhibition and peroxisome proliferator—activated receptor α (PPARα) agonism on lipid profiles. Torcetrapib (3, 10, and 30 mg/kg), a CETP inhibitor, fenofibrate (30 mg/kg), a weak PPARα agonist, and GW590735 (3 and 10 mg/kg), a potent and selective PPARα agonist were given orally for 14 days to hApoB100/hCETP mice and lipid profiles were assessed. The average percentages of HDL, low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL) cholesterol fractions in hApoB100/hCETP mice were 34.8%, 61.6%, and 3.6%, respectively, which is similar to those of normolipidemic humans. Both torcetrapib and fenofibrate significantly increased HDL cholesterol and reduced LDL cholesterol, and there was a tendency for torcetrapib to reduce VLDL cholesterol and triglycerides. GW590735 significantly increased HDL cholesterol, decreased LDL and VLDL cholesterol, and significantly reduced triglycerides. Maximal increases in HDL cholesterol were 37%, 53%, and 84% with fenofibrate, torcetrapib, and GW590735, respectively. These results, in mice that exhibit a more human-like lipid profile, demonstrate an improved lipid profile with torcetrapib, fenofibrate, and GW590735, and support the use of selective PPARα agonism for the treatment of lipid disorders. In addition, these data demonstrate the use of hApoB100/hCETP transgenic mice to identify, characterize, and screen compounds that increase HDL cholesterol.
Bak has been shown to both promote apoptosis and to inhibit cell death while two other members of the Bcl-2 family of proteins, Bcl-XL and Bcl-2 delay apoptosis induced by various stimuli including ...chemotherapeutic agents. We generated clones with stable expression of Bak wild-type (wt) and Bak with its BH3 (delta78-86) domain deleted (deltaBH3) in FL5.12 cells or FL5.12 cells expressing either Bcl-XL or Bcl-2 to determine if Bak could accelerate apoptosis and antagonize the death repressor activity of Bcl-XL and Bcl-2 during chemotherapy-induced apoptosis. We found that Bak accelerated cell death in FL5.12 cells treated with etoposide, fluorouracil or taxol. In FL5.12 cells expressing Bcl-XL and Bak wt or Bak deltaBH3, both Bak wt or Bak deltaBH3 were able to antagonize the protective effect of Bcl-XL when treated with etoposide or fluorouracil. Bak wt or Bak deltaBH3 were also able to abrogate the protective effect of Bcl-2 in cells expressing Bcl-2 and Bak wt or Bak deltaBH3 when challenged by etoposide or fluorouracil. Immunoprecipitation studies revealed that deletion of BH3 disrupted heterodimerization between Bak and Bcl-XL and that both Bak wt and Bak deltaBH3 failed to interact with Bcl-2. These results demonstrate that Bak does not require its BH3 domain to promote apoptosis in stably transfected cells. Furthermore, Bak can accelerate chemotherapy-induced cell death independently of its heterodimerization with Bcl-XL and Bcl-2.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Bax, a member of the Bcl-2 family of proteins, has been shown to accelerate apoptosis induced by growth factor withdrawal, γ-irradiation, and the chemotherapeutic agent, etoposide. The mechanism by ...which Bax promotes apoptosis is poorly understood. Bax forms homodimers which have been suggested to act as accelerators or inducers of cell death. However, the requirement for homodimerization of Bax to promote cell death remains unclear. We performed site-directed mutagenesis of the BH1, BH2, and BH3 in Bax to determine the regions of Bax required for homodimerization and to define the role of Bax homodimers in cell death induced by chemotherapy drugs. Bax proteins expressing alanine substitutions of the highly conserved amino acids glycine 108 (G108) in BH1, tryptophan 158 (W158) in BH2, and glycine 67 and aspartic acid 68 (GD67-68) in BH3 as well as deletion of the most conserved amino acids in BH1 (Δ102-112) and BH2 (Δ151-159) and deletion of BH3 (Δ63-71) maintained their ability to accelerate chemotherapy-induced cell death. Immunoprecipitation studies revealed that Bax with deletions in BH1 and BH2 still associated with wild-type Bax while deletion of BH3 disrupted Bax homodimerization. These results demonstrate that Bax does not require the conserved regions of homology, BH1, BH2, or BH3, to accelerate chemotherapy-induced cell death. Furthermore, our results established BH3 as a region required for Bax homodimerization in mammalian cells and demonstrate that monomeric forms of Bax are active in accelerating cell death induced by chemotherapy agents.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cholesteryl ester transfer protein (CETP) plays a key role in high-density lipoprotein (HDL) cholesterol metabolism, but normal mice are deficient in CETP. In this study, transgenic mice expressing ...both human apolipoprotein B 100 (ApoB-100) and human CETP (hApoB100/hCETP) were used to characterize the effects of CETP inhibition and peroxisome proliferator-activated receptor a (PPARa) agonism on lipid profiles. Torcetrapib (3, 10, and 30 mg/kg), a CETP inhibitor, fenofibrate (30 mg/kg), a weak PPARa agonist, and GW590735 (3 and 10 mg/kg), a potent and selective PPARa agonist were given orally for 14 days to hApoB100/hCETP mice and lipid profiles were assessed. The average percentages of HDL, low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL) cholesterol fractions in hApoB100/hCETP mice were 34.8%, 61.6%, and 3.6%, respectively, which is similar to those of normolipidemic humans. Both torcetrapib and fenofibrate significantly increased HDL cholesterol and reduced LDL cholesterol, and there was a tendency for torcetrapib to reduce VLDL cholesterol and triglycerides. GW590735 significantly increased HDL cholesterol, decreased LDL and VLDL cholesterol, and significantly reduced triglycerides. Maximal increases in HDL cholesterol were 37%, 53%, and 84% with fenofibrate, torcetrapib, and GW590735, respectively. These results, in mice that exhibit a more human-like lipid profile, demonstrate an improved lipid profile with torcetrapib, fenofibrate, and GW590735, and support the use of selective PPARa agonism for the treatment of lipid disorders. In addition, these data demonstrate the use of hApoB100/hCETP transgenic mice to identify, characterize, and screen compounds that increase HDL cholesterol.
The peroxisome proliferator activated receptors PPARalpha, PPARgamma, and PPARdelta are ligand-activated transcription factors that play a key role in lipid homeostasis. The fibrates raise ...circulating levels of high-density lipoprotein cholesterol and lower levels of triglycerides in part through their activity as PPARalpha agonists; however, the low potency and restricted selectivity of the fibrates may limit their efficacy, and it would be desirable to develop more potent and selective PPARalpha agonists. Modification of the selective PPARdelta agonist 1 (GW501516) so as to incorporate the 2-aryl-2-methylpropionic acid group of the fibrates led to a marked shift in potency and selectivity toward PPARalpha agonism. Optimization of the series gave 25a, which shows EC50 = 4 nM on PPARalpha and at least 500-fold selectivity versus PPARdelta and PPARgamma. Compound 25a (GW590735) has been progressed to clinical trials for the treatment of diseases of lipid imbalance.
This study deals with the communication capabilities of two kinds of semiconductor lasers emitting in one of the atmosphere transparency windows, around 4 <inline-formula><tex-math ...notation="LaTeX">\mu</tex-math></inline-formula>m. One of these two lasers is a quantum cascade laser and the other one is an interband cascade laser. With the quantum cascade laser, a subsequent attenuation is added to the optical path in order to mimic the attenuation of free-space transmission of several kilometers. Direct electrical modulation is used to transmit the message and two-level formats, non-return-to-zero and return-to-zero, are used and compared in terms of maximum transmission data rate. The sensitivity to optical feedback is also analyzed, as well as the evolution of the error rate when reducing the optical power at the level of the detector. This work provides a novel insight into the development of future secure free-space optical communication links based on mid-infrared semiconductor lasers and sheds the light on improvements required to achieve multi-Gbits/s communication with off-the-shelf components.
Cholesteryl ester transfer protein (CETP) plays a key role in high-density lipoprotein (HDL) cholesterol metabolism, but normal mice are deficient in CETP. In this study, transgenic mice expressing ...both human apolipoprotein B 100 (ApoB-100) and human CETP (hApoB100/hCETP) were used to characterize the effects of CETP inhibition and peroxisome proliferator-activated receptor alpha (PPARalpha) agonism on lipid profiles. Torcetrapib (3, 10, and 30 mg/kg), a CETP inhibitor, fenofibrate (30 mg/kg), a weak PPARalpha agonist, and GW590735 (3 and 10 mg/kg), a potent and selective PPARalpha agonist were given orally for 14 days to hApoB100/hCETP mice and lipid profiles were assessed. The average percentages of HDL, low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL) cholesterol fractions in hApoB100/hCETP mice were 34.8%, 61.6%, and 3.6%, respectively, which is similar to those of normolipidemic humans. Both torcetrapib and fenofibrate significantly increased HDL cholesterol and reduced LDL cholesterol, and there was a tendency for torcetrapib to reduce VLDL cholesterol and triglycerides. GW590735 significantly increased HDL cholesterol, decreased LDL and VLDL cholesterol, and significantly reduced triglycerides. Maximal increases in HDL cholesterol were 37%, 53%, and 84% with fenofibrate, torcetrapib, and GW590735, respectively. These results, in mice that exhibit a more human-like lipid profile, demonstrate an improved lipid profile with torcetrapib, fenofibrate, and GW590735, and support the use of selective PPARalpha agonism for the treatment of lipid disorders. In addition, these data demonstrate the use of hApoB100/hCETP transgenic mice to identify, characterize, and screen compounds that increase HDL cholesterol.
Concomitant radiochemotherapy (RCT) is the standard for locally advanced anal canal carcinoma (LAACC). Questions regarding the role of induction chemotherapy (ICT) and a higher radiation dose in ...LAACC are pending. Our trial was designed to determine whether dose escalation of the radiation boost or two cycles of ICT before concomitant RCT lead to an improvement in colostomy-free survival (CFS).
Patients with tumors ≥ 40 mm, or < 40 mm and N1-3M0 were randomly assigned to one of four treatment arms: (A) two ICT cycles (fluorouracil 800 mg/m(2)/d intravenous IV infusion, days 1 through 4 and 29 to 32; and cisplatin 80 mg/m(2) IV, on days 1 and 29), RCT (45 Gy in 25 fractions over 5 weeks, fluorouracil and cisplatin during weeks 1 and 5), and standard-dose boost (SD; 15 Gy); (B) two ICT cycles, RCT, and high-dose boost (HD; 20-25 Gy); (C): RCT and SD boost (reference arm); and (D) RCT and HD boost.
Two hundred eighty-three of 307 patients achieved full treatment. With a median follow-up period of 50 months, the 5-year CFS rates were 69.6%, 82.4%, 77.1%, and 72.7% in arms A, B, C, and D, respectively. Considering the 2 × 2 factorial analysis, the 5-year CFS was 76.5% versus 75.0% (P = .37) in groups A and B versus C and D, respectively (ICT effect), and 73.7% versus 77.8% in groups A and C versus B and D, respectively (RT-dose effect; P = .067).
Using CFS as our main end point, we did not find an advantage for either ICT or HD radiation boost in LAACC. Nevertheless, the results of the most treatment-intense arm B should prompt the design of further intensification studies.
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