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At least 1,585 records · Page 88Linked to original sources
PubMed2006

Efficacy of the protease inhibitors tipranavir plus ritonavir in treatment-experienced patients: 24-week analysis from the RESIST-1 trial.

BACKGROUND: Improved treatment options are needed for patients infected with multidrug-resistant human immunodeficiency virus type 1 (HIV-1). The nonpeptidic protease inhibitor tipranavir has demonstrated antiviral activity against many protease inhibitor-resistant HIV-1 isolates. The Randomized Evaluation of Strategic Intervention in multi-drug reSistant patients with Tipranavir (RESIST-1) trial is an ongoing, open-label study comparing the efficacy and safety of ritonavir-boosted tipranavir (TPV/r) with an investigator-selected ritonavir-boosted comparator protease inhibitor (CPI/r) in treatment-experienced, HIV-1-infected patients. METHODS: Six hundred twenty antiretroviral-experienced patients were treated at 125 sites in North America and Australia. Before randomization, all patients underwent genotypic resistance testing, which investigators used to select a CPI/r and an optimized background regimen. Patients were randomized to receive TPV/r or CPI/r and were stratified on the basis of preselected protease inhibitor and enfuvirtide use. Treatment response was defined as a confirmed reduction in the HIV-1 load of > or = 1 log10 less than the baseline level without treatment change at week 24. RESULTS: Mean baseline HIV-1 loads and CD4+ cell counts were 4.74 log10 copies/mL and 164 cells/mm3, respectively. At week 24, a total of 41.5% of patients in the TPV/r arm and 22.3% in the CPI/r arm had a > or = 1-log10 reduction in the HIV-1 load (intent-to-treat population; P<.0001). Mean increases in the CD4+ cell count of 54 and 24 cells/mm3 occurred in the TPV/r and CPI/r groups, respectively. Adverse events were slightly more common in the TPV/r group and included diarrhea, nausea, and vomiting. Elevations in alanine and aspartate aminotransferase levels and in cholesterol/triglyceride levels were more frequent in the TPV/r group. CONCLUSIONS: TPV/r demonstrated superior antiviral activity, compared with investigator-selected, ritonavir-boosted protease inhibitors, at week 24 in treatment-experienced patients with multidrug-resistant HIV-1 infection.

Adult↗
PubMed2002

Leustroducsin B activates nuclear factor-kappaB via the acidic sphingomyelinase pathway in human bone marrow-derived stromal cell line KM-102.

The novel colony-stimulating factor (CSF) inducer leustroducsin B (LSN-B), which was isolated from Streptomyces platensis, has been shown to have potent cytokine-inducing activities in clonal human bone marrow-derived stromal cell line KM-102 and in primary human bone marrow-derived stromal cells. In this study, we investigated the signal transduction pathway of LSN-B using luciferase expression plasmids linked to the 5'-flanking region of interleukin-8 (IL-8) and that of the IL-11 gene. In KM-102 cells, LSN-B induced luciferase activity both in the wild-type and in the activated protein 1 (AP-1) site point-mutated IL-8 promoter. The mutation in the nuclear factor-kappaB (NF-kappaB) site abrogated LSN-B-stimulated induction of the reporter gene. LSN-B-inducing activity was inhibited by (1) N-acetyl-L-cysteine, a well-characterized antioxidant, (2) cationic amphiphilic drugs, inhibitors of acidic sphingomyelinase (A-SMase), and (3) D609, an inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC). These observations suggest that LSN-B potentiates the A-SMase-mediated signaling pathway to stimulate NF-kappaB. In contrast, LSN-B did not induce IL-11 promoter-driven luciferase activity. The observed increase in IL-11 mRNA stability by LSN-B indicates that the inducible production of IL-11 by LSN-B is regulated at the posttranscriptional level. In addition, inhibition of LSN-B-mediated induction of IL-11 production by cationic amphiphilic drugs and D609 in KM-102 cells demonstrates that increased IL-11 mRNA stability by LSN-B might be mediated via NF-kappaB activation. From these results, we suggest that LSN-B induces cytokine production through at least two separate mechanisms, at the transcriptional level and at the posttranscriptional level via NF-kappaB activation.

Acetylcysteine↗
PubMed1996

A simple and efficient method for the concentration and purification of recombinant retrovirus for increased hepatocyte transduction in vivo.

Although recombinant retroviruses have been widely used for the transduction of target organs in vivo, the viral titers achieved by current production methods are often too low to achieve therapeutic levels of gene expression. To overcome this limitation, a simple method for the efficient concentration and purification of amphotropic retrovirus particles was developed. After portal vein infusion into partially hepatectomized rats of 5.5 x 10(7) cfu of a beta-galactosidase (beta-gal)-expressing retrovirus (LX/beta geo) concentrated by this method, up to 25% of hepatocytes stained positive for beta-Gal activity. Measurement of human alpha 1-antitrypsin (hAAT) levels after infusion of various doses of a similarly concentrated retrovirus encoding hAAT (LX/hAAT) demonstrated that viral transduction increased proportionally with titer, up to a dose of 7.5 x 10(7) cfu per rat. The ability to concentrate retroviral virion efficiently from large volumes of supernatant has allowed the further purification of virus particles by sucrose banding ultracentrifugation. This procedure results in a greater than 50% recovery of infectious virus particles, with titers up to 500-fold higher than in the original supernatant. These methods may have significant utility in both ex vivo and in vivo retroviral applications in human gene therapy.

Animals↗
PubMed1998

The effect of leustroducsin B on the production of cytokines by human mesenchymal cells.

Leustroducsin B (LSN-B), a novel colony-stimulating factor (CSF) inducer, has been shown to have various biologic activities in vivo. To compare the CSF-inducing activity of LSN-B in vitro with that of the well-known cytokine inducer, interleukin-1beta (IL-1beta), bacterial lipopolysaccharide (LPS), and phorbol 12-myristate 13-acetate (PMA), we measured granulocyte (G)-CSF and granulocyte-macrophage (GM)-CSF levels that were induced with the stimuli in several mesenchymal cells. The results indicated that each stimulant displayed a different profile in the induction of G-CSF and GM-CSF. Next, to investigate if LSN-B induces cytokines other than G-CSF and GM-CSF, we characterized cytokines that were induced with LSN-B from bone marrow stromal cells (BMSCs). The results showed that a variety of cytokines, including G-CSF and GM-CSF, were induced in both clonal and primary BMSCs. From these results, we speculate that LSN-B induces cytokine production via a regulatory pathway distinct from that of IL-1beta, LPS, or PMA and that this signaling of LSN-B might lead to the production of a variety of cytokines in BMSCs. In addition, from our in vitro and in vivo results, we speculate that the biologic activities of LSN-B in vivo might be based on its own cytokine-inducing activity even though the target cell type of LSN-B in vivo remains to be determined.

Anti-Bacterial Agents↗
PubMed2005

Nuclear targeting of adenovirus type 2 requires CRM1-mediated nuclear export.

Incoming adenovirus type 2 (Ad2) and Ad5 shuttle bidirectionally along microtubules, biased to the microtubule-organizing center by the dynein/dynactin motor complex. It is unknown how the particles reach the nuclear pore complex, where capsids disassemble and viral DNA enters the nucleus. Here, we identified a novel link between nuclear export and microtubule-mediated transport. Two distinct inhibitors of the nuclear export factor CRM1, leptomycin B (LMB) and ratjadone A (RJA) or CRM1-siRNAs blocked adenovirus infection, arrested cytoplasmic transport of viral particles at the microtubule-organizing center or in the cytoplasm and prevented capsid disassembly and nuclear import of the viral genome. In mitotic cells where CRM1 is in the cytoplasm, adenovirus particles were not associated with microtubules but upon LMB treatment, they enriched at the spindle poles implying that CRM1 inhibited microtubule association of adenovirus. We propose that CRM1, a nuclear factor exported by CRM1 or a protein complex containing CRM1 is part of a sensor mechanism triggering the unloading of the incoming adenovirus particles from microtubules proximal to the nucleus of interphase cells.

Active Transport, Cell Nucleus↗
PubMed1992

Effect of topoisomerase poisoning by antitumor drugs VM 26, fostriecin and camptothecin on DNA repair replication by mammalian cell extracts.

A recently developed in vitro excision-repair system was used to investigate the effect of the topoisomerase poisons VM 26, fostriecin and camptothecin on DNA repair replication carried out by Chinese hamster ovary cell extracts. VM 26 and camptothecin partially inhibit topoisomerases II and I respectively, which are present in the repair-competent extracts, but have only slight effects on the repair efficiency. On the contrary, the antitumor drug fostriecin markedly affects repair replication but, in contrast to a previous report, does not seem to have, under the experimental conditions used, any inhibitory effect on topoisomerase II. This lack of correlation between the ability to inhibit DNA topoisomerases and the effect on DNA repair replication suggests that topoisomerases should not play a primary role in mammalian excision repair. The use of cleavable-complex stabilizing poisons to investigate the role of eukaryotic topoisomerases in DNA excision repair is discussed.

Alkenes↗
PubMed1996

The antitumor drug fostriecin induces vimentin hyperphosphorylation and intermediate filament reorganization.

Fostriecin is an antitumor drug in phase I clinical trials. We have recently shown that it is a potent inhibitor of protein phosphatases 1 and 2A in vitro, a property not previously described for an antitumor drug. We have investigated its effects on protein phosphorylation in baby hamster kidney cells. Fostriecin strongly stimulated the phosphorylation of a single protein, which we identified as the intermediate filament vimentin. Fostriecin also caused rounding of the cells and a reorganization of the vimentin filaments. These effects are similar to those of the known protein phosphatase 1 and 2A inhibitors okadaic acid and calyculin A, which are also tumor promoters. Fostriecin induced vimentin hyperphosphorylation mostly at two sites, which were sensitive to staurosporine and could be phosphorylated by protein kinase C in vitro. Fostriecin-induced vimentin hyperphosphorylation also occurred in cells that lack p34cdc2 kinase activity. These results suggest that protein kinase C plays a direct or indirect role in vimentin hyperphosphorylation during exposure to fostriecin. The results also provide strong evidence that fostriecin inhibits protein phosphatases 1 and 2A in vivo and raise the possibility that it may have tumor-promoting activity.

Alkaloids↗
PubMed1999

Promoting effects of kojic acid due to serum TSH elevation resulting from reduced serum thyroid hormone levels on development of thyroid proliferative lesions in rats initiated with N-bis(2-hydroxypropyl)nitrosamine.

In order to examine whether kojic acid (KA) exerts a promoting effect on thyroid carcinogenesis, male F344 rats were initiated with N-bis(2-hydroxypropyl)nitrosamine (BHP; 2800 mg/kg body wt, single s.c. injection) and, starting 1 week later, received pulverized basal diet containing 2 or 0% KA for 12 weeks. Untreated control rats were given basal diet for 13 weeks. As an additional experiment, two groups without BHP initiation received basal diet or diet containing 2% KA for 20 weeks. The serum triiodothyronine (T3) and thyroxine (T4) levels were significantly decreased (half to one-third of values of the BHP alone group) and serum thyroid-stimulating hormone (TSH) was markedly increased (13-19 times higher than the values of the BHP-alone group) in the BHP + KA group at weeks 4 and 12. Similar changes in serum thyroid-related hormones were observed in the group with 2% KA alone at week 4, but not at week 20. Thyroid weights were significantly increased in the BHP + KA and KA-alone groups. Focal thyroid follicular hyperplasias and adenomas were observed in 4/5 and 3/ 5 rats in the BHP + KA group at week 4, respectively. At weeks 12, these lesions were observed in all rats in the BHP + KA group. Animals of the KA alone group showed marked diffuse hypertrophy of follicular epithelial cells at weeks 4 and 20. No changes in thyroid-related hormone levels or thyroid histopathological lesions were observed in either the BHP alone or the untreated control groups. Measurement of liver T4-uridine diphosphate glucuronosyltransferase (UDP-GT) activity at week 4 revealed no significant intergroup differences. These results suggest that thyroid proliferative lesions were induced by KA administration due to continuous serum TSH stimulation through the negative feedback mechanism of the pituitary-thyroid axis, with decreases of T3 and T4 caused by a mechanism independent of T4-UDP-GT activity.

Adenoma↗
PubMed1999

Changes in thyroid function during development of thyroid hyperplasia induced by kojic acid in F344 rats.

To clarify the mechanism of tumorigenesis by kojic acid (KA), dose and time dependence of iodine uptake in the thyroid gland and serum thyroid stimulating hormone (TSH) and thyroid hormone levels were investigated in F344 rats fed a diet containing 2% KA. After 4 weeks, thyroid hyperplasia was apparent in males, associated with a decrease in (125)I uptake into the thyroid gland to only 3% of that in controls. The serum triiodothyronine (T(3)) and thyroxine (T(4)) levels dropped to 0.36 ng/ml, 1.7 micrograms/dl from the initial values of 0.61 ng/ml, 4.0 micrograms/dl and TSH increased seven times to 15 ng/ml. In females, the effects on thyroid weight and (125)I uptake were less prominent, although the changes in serum T(3), T(4) and TSH levels were similar to those in males. Time-dependent changes in serum T(3), T(4) and TSH levels correlated with the inhibition of iodine uptake in the thyroid. Inhibition of organic iodine formation was only observed after 3 weeks treatment. On return to the control diet, normal serum T(3), T(4) and TSH levels became evident within 48 h in both sexes. These data suggest that KA interrupts thyroid function, primarily by inhibiting iodine intake, consequently causing a decrease in serum T(3) and T(4). Increased TSH from the pituitary gland in turn stimulates thyroid hyperplasia, which is reversible on withdrawal of KA.

Animals↗
PubMed1996

Construction of a quantitative three-dimensional model for odor quality using comparative molecular field analysis (CoMFA).

A quantitative structure-activity relationship (QSAR) study of odorants was performed taking an odor as an activity. As an example, we took the 'green odor of pyrazine derivations' as an activity. Conformational analysis of the pyrazine derivatives was performed, and conformers were selected using the longest side-length of a circumscribed box (LLCB) as a criterion. Comparative molecular field analysis (CoMFA) was used to elucidate the three-dimensional (3D) structural features of the derivatives. As a result, it was found that the steric and electrostatic features of the derivations were correlated with human olfactory detection threshold values. We constructed a quantitative 3D model using the graphic views of CoMFA and partial structures of the derivatives. The prediction of human olfactory detection threshold values of other pyrazine derivatives with green odor was possible by using the 3D model. As another example, we took the 'sweet odor of compounds with various structures' as an activity. A quantitative 3D model for sweet odor was constructed in the same manner. Analysing the structural features of odorants by CoMFA and constructing 3D models for several important odor qualities would help to (i) explain or predict human olfactory detection threshold values of interesting odorants, (ii) design new odorants by suggesting the steric and electrostatic requirements, and (iii) elucidate the mechanism of odorant-receptor interaction.

Aldehydes↗
PubMed2006

Subthreshold olfactory stimulation can enhance sweetness.

The impact of olfactory perception on sweetness was explored in a model solution using odorants at subthreshold concentrations. First, the impact of 6 odorants, previously described in the literature as congruent with sweetness, was investigated at suprathreshold level in a sucrose solution. Ethyl butyrate and maltol were selected as they had the highest and the lowest sweetness-enhancing properties, respectively. Second, the impact on sweetness of the 2 odorants was investigated at subthreshold concentrations. A system delivering a continuous liquid flow at the same sucrose level, but with varying odorant concentrations, was used. At a subthreshold level, ethyl butyrate but not maltol significantly enhanced the sweetness of the sucrose solution. This study highlights that olfactory perception induced by odorants at a subthreshold level can significantly modulate taste perception. Finally, contrary to results observed with ethyl butyrate at suprathreshold levels, at subthreshold levels, the intensity of sweetness enhancement was not proportional to ethyl butyrate concentration.

Adolescent↗
PubMed2004

Analysis of protease inhibitor combinations in vitro: activity of lopinavir, amprenavir and tipranavir against HIV type 1 wild-type and drug-resistant isolates.

BACKGROUND: Despite the increasing number of antiretroviral compounds, the number of useful drug regimens is limited owing to the high frequency of cross-resistance. PATIENTS AND METHODS: We studied in vitro two-drug combinations using three protease inhibitors (PIs), tipranavir, amprenavir and lopinavir, on isolates (003 and 004) derived from patients with resistance to multiple PIs compared with the drug-susceptible isolate 14aPre in peripheral blood mononuclear cells. Drug interactions were determined by median dose-effect analysis, with the combination index calculated at several inhibitory concentrations (IC). RESULTS: In 14aPre experiments, the combination tipranavir + lopinavir demonstrated synergy at low concentrations (IC(50)), an additive effect at IC(75) and antagonism at IC(90)-IC(95); tipranavir + amprenavir were antagonistic at all concentrations except IC(95), where they were synergic; and the lopinavir + amprenavir combination was always antagonistic. In 003 and 004 infections, tipranavir + lopinavir and tipranavir + amprenavir combinations were antagonistic, and lopinavir + amprenavir were synergic, at all concentrations, with the exception of being additive at IC(95). CONCLUSIONS: Our in vitro experiments did not show any advantage in combining second generation PIs as a therapeutic strategy in naive or multi-treatment failure subjects, with the exception of tipranavir + amprenavir at IC(95) in infections by a wild-type isolate.

Carbamates↗
PubMed2006

Suppression of LDL oxidation by garlic compounds is a possible mechanism of cardiovascular health benefit.

Hypercholesterolemia is a major risk factor for atherosclerosis, and lowering cholesterol can significantly reduce the risk for cardiovascular diseases. Oxidation of LDL has recently been recognized as playing an important role in the initiation and progression of atherosclerosis. Oxidized LDL, but not native LDL, promotes vascular dysfunction by exerting direct cytotoxicity to endothelial cells, by increasing chemotactic properties of monocytes, by transforming macrophages to foam cells, and by enhancing the proliferation of endothelial cells, monocytes, and muscle cells. All these events are recognized as contributors to cardiovascular diseases. This paper presents experimental evidence showing that several garlic compounds can suppress LDL oxidation in vitro. Short-term supplementation of garlic in human subjects has demonstrated an increased resistance of LDL to oxidation. These data suggest that suppressed LDL oxidation may be one of the mechanisms that accounts for the beneficial effects of garlic in cardiovascular health.

Cardiovascular Diseases↗
PubMed1994

9-Methoxytariacuripyrone, a naturally occurring nitro-aromatic compound with strong mutagenicity in Salmonella typhimurium.

9-Methoxytariacuripyrone, a nitro-aromatic compound isolated from Aristolochia brevipes showed strong mutagenic activity in strain TA98, TA100 and some YG strains of Salmonella typhimurium with and without S9 mix. Incubation with cytosol resulted in a heavy increase in mutagenicity. When incubated with microsomes the activity was dramatically decreased. The results are discussed in view of the enzymes possibly involved in activation and detoxification of the compound. The role of the basic structure on the mutagenicity mediated through the nitro group was also considered.

Animals↗
PubMed2006

Mutagenicity of UV-irradiated maltol in Salmonella typhimurium.

We investigated the photomutagenicity of maltol (3-hydroxy-2-methyl-4H-pyran-4-one) in bacterial cells. Maltol has a caramel-butterscotch odour and is used as a food additive to impart flavour to bread and cakes. Unirradiated maltol was not mutagenic up to 5 mg/plate in the Ames test. When maltol was irradiated with either UVA (a black light, 320-400 nm, 230 microW/cm(2)) for 5-30 min or UVC (a germicidal lamp, 610 microW/cm(2)) for 3 min in sodium phosphate buffer (pH 7.4) prior to the exposure of bacterial cells, it was mutagenic to Salmonella typhimurium TA100, TA104 and TA97. Mutagenic activation of maltol by UVA-irradiation was more evident in neutral and alkaline conditions (pH 7.0-9.0) than in acidic conditions. On the other hand, photomutagenicity was not observed when maltol was irradiated with UVA in 100 mM NaCl solution or water. The mutagenic photoproduct was stable for at least 60 min after UVA-irradiation. However, addition of thiol compounds (cysteine or glutathione) to the UVA-irradiated maltol diminished the mutagenicity. Mutational spectrum analysis revealed that the predominant base-substitutions induced were G:C-->T:A transversions and G:C-->A:T transitions. An increase of 8-hydroxydeoxyguanosine formation in salmon sperm DNA exposed to maltol and UVA in vitro was detected by HPLC-ECD, but it was too small to explain the photomutagenicity. We are considering the formation of DNA adducts as the photomutagenic mechanism.

8-Hydroxy-2'-Deoxyguanosine↗