Selective Inhibition (selective + inhibition)

Distribution by Scientific Domains
Distribution within Medical Sciences


Selected Abstracts


A Critical Appraisal of COX-2 Selective Inhibition and Analgesia: How Good So Far?

PAIN PRACTICE, Issue 3 2003
Pedro F. Bejarano MD
Abstract: The development of COX-2 selective inhibitors has opened a new era of clinical investigation in NSAIDs. Discussion of the established concepts of inflammation and therapeutical uses of these drugs has changed the rationale for its clinical use and therapeutic labeling of these drugs. A comprehensive discussion across basic science and clinical areas involved in each of these concepts is presented. This led to a remarkable re-evaluation of our insights on their traditionally proposed mechanisms of analgesia, their side-effects, and the clinical indication of NSAIDs as "over the counter" pain killers. This may shift physicians toward a more rational use of this drug class. [source]


Selective Inhibition of Human Brain Tumor Cells through Multifunctional Quantum-Dot-Based siRNA Delivery,

ANGEWANDTE CHEMIE, Issue 1 2010
Jongjin Jung
Auf den Punkt gebracht: Quantenpunkte (QDs), die mit thiolmodifizierter small interfering RNA (siRNA) konjugiert sind, wurden mit thiolmodifizierten RGD- und HIV-Tat-Peptiden funktionalisiert. Diese multifunktionellen QDs wurden fr den zielgerichteten Transport und die Verfolgung von siRNA-Moleklen zum Knockdown des fr EGFRvIII kodierenden Gens genutzt, was zur Herunterregulierung des PI3K-Akt-Signalwegs und zur Apoptose maligner Gehirntumorzellen fhrte. [source]


Selective Inhibition of Hepatoma Cells Using Diphtheria Toxin A under the Control of the Promoter/Enhancer Region of the Human ,-Fetoprotein Gene

CANCER SCIENCE, Issue 3 2000
Michito Kunitomi
We constructed a plasmid containing human ,-fetoprotein (AFP) promoter/enhancer to direct the cell type-specific expression of diphtheria toxin fragment A (DTA), designated as pAF-DTA, to AFP-producing hepatocellular carcinoma cells. The transfection was carried out with cationic liposomes (DMRIE-C) and the expression of the DTA gene was confirmed by a northern blot analysis. When pAF-DTA was transfected, the growth of AFP-positive HuH-7 cells was inhibited, whereas growth inhibition was not observed in AFP-negative MKN45 cells. In this experiment, the secretion of AFP was similarly suppressed, but the secretion of carcinoembryonic antigen from MKN45 was not altered. pAF-DTA could also exert its growth inhibitory effect on PLC, a cell line with a low level of AFP. However, no inhibitory effect of pAF-DTA was observed on the proliferation of primary hepatocyte cells. Furthermore, transfection experiments in which HuH-7 and splenic stromal cells were co-cultured revealed the growth inhibition by pAF-DTA to be selective in HuH-7 cells. Finally, the growth of HuH-7 transplanted on BALB/c nu/nu mice was inhibited by the direct injection of pAF-DTA/liposome complex into a tumor mass. These results suggest that use of pAF-DTA may be potentially useful as a novel approach for the selective treatment of tumor cells producing AFP even at low levels, without affecting other types of cells. [source]


Myosin-II negatively regulates minor process extension and the temporal development of neuronal polarity

DEVELOPMENTAL NEUROBIOLOGY, Issue 5 2009
K.M. Kollins
Abstract The earliest stage in the development of neuronal polarity is characterized by extension of undifferentiated "minor processes" (MPs), which subsequently differentiate into the axon and dendrites. We investigated the role of the myosin II motor protein in MP extension using forebrain and hippocampal neuron cultures. Chronic treatment of neurons with the myosin II ATPase inhibitor blebbistatin increased MP length, which was also seen in myosin IIB knockouts. Through live-cell imaging, we demonstrate that myosin II inhibition triggers rapid minor process extension to a maximum length range. Myosin II activity is determined by phosphorylation of its regulatory light chains (rMLC) and mediated by myosin light chain kinase (MLCK) or RhoA-kinase (ROCK). Pharmacological inhibition of MLCK or ROCK increased MP length moderately, with combined inhibition of these kinases resulting in an additive increase in MP length similar to the effect of direct inhibition of myosin II. Selective inhibition of RhoA signaling upstream of ROCK, with cell-permeable C3 transferase, increased both the length and number of MPs. To determine whether myosin II affected development of neuronal polarity, MP differentiation was examined in cultures treated with direct or indirect myosin II inhibitors. Significantly, inhibition of myosin II, MLCK, or ROCK accelerated the development of neuronal polarity. Increased myosin II activity, through constitutively active MLCK or RhoA, decreased both the length and number of MPs and, consequently, delayed or abolished the development of neuronal polarity. Together, these data indicate that myosin II negatively regulates MP extension, and the developmental time course for axonogenesis. 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source]


Caspase-8- and JNK-dependent AP-1 activation is required for Fas ligand-induced IL-8 production

FEBS JOURNAL, Issue 9 2007
Norihiko Matsumoto
Despite a dogma that apoptosis does not induce inflammation, Fas ligand (FasL), a well-known death factor, possesses pro-inflammatory activity. For example, FasL induces nuclear factor ,B (NF-,B) activity and interleukin 8 (IL-8) production by engagement of Fas in human cells. Here, we found that a dominant negative mutant of c-Jun, a component of the activator protein-1 (AP-1) transcription factor, inhibits FasL-induced AP-1 activity and IL-8 production in HEK293 cells. Selective inhibition of AP-1 did not affect NF-,B activation and vice versa, indicating that their activations were not sequential events. The FasL-induced AP-1 activation could be inhibited by deleting or introducing the lymphoproliferation (lpr) -type point mutation into the Fas death domain (DD), knocking down the Fas-associated DD protein (FADD), abrogating caspase-8 expression with small interfering RNAs, or using inhibitors for pan-caspase and caspase-8 but not caspase-1 or caspase-3. Furthermore, wildtype, but not a catalytically inactive mutant, of caspase-8 reconstituted the FasL-induced AP-1 activation in caspase-8-deficient cells. Fas ligand induced the phosphorylation of two of the three major mitogen-activated protein kinases (MAPKs): extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) but not p38 MAPK. Unexpectedly, an inhibitor for JNK but not for MAPK/ERK kinase inhibited the FasL-induced AP-1 activation and IL-8 production. These results demonstrate that FasL-induced AP-1 activation is required for optimal IL-8 production, and this process is mediated by FADD, caspase-8, and JNK. [source]


Selective inhibition of Porphyromonas gingivalis growth by a factor Xa inhibitor, DX-9065a

JOURNAL OF PERIODONTAL RESEARCH, Issue 3 2006
Kenji Matsushita
Background:,Porphyromonas gingivalis is a causative bacterium of adult periodontitis. However, there is no drug specific for P. gingivalis and for its virulence factor. Objectives:, The objective of this study was to examine the effects of a new selective inhibitor of activated factor X, DX-9065a, on growth of Porphyromonas gingivalis and other periodontopathic bacteria. Methods:, We incubated P. gingivalis and other periodontopathic bacteria in the presence or absence of DX-9065a and examined the effect of DX-9065a on bacterial growth and trypsin-like activity in its cultures. We also examined the effects of DX9065a on amidolytic activity of purified trypsin-like proteinases (gingipains RgpA and RgpB), from P. gingivalis and on trypsin-like activity in gingival crevicular fluids from patients with adult periodontitis. Results:, DX-9065a selectively inhibited the growth of P. gingivalis and Prevotella intermedia, and its effect on P. gingivalis was bactericidal. Trypsin-like proteinase activity was detected in P. gingivalis, and the activity was strongly inhibited by DX-9065a. DX-9065a even inhibited amidolytic activity of RgpA and RgpB from P. gingivalis. Furthermore, trypsin-like proteinase activity in gingival crevicular fluids was strongly inhibited by DX-9065a. Conclusions:, DX-9065a inhibits P. gingivalis growth in part through to its ability to inhibit the trypsin-like proteinase activity in P. gingivalis and may be useful for a new drug for treatment of adult periodontitis. [source]


Inhibition of the initial wave of NF-,B activity in rat muscle reduces ischemia/reperfusion injury

MUSCLE AND NERVE, Issue 4 2001
Sean T. Lille MD
Abstract Nuclear factor kappaB (NF-,B) is thought to play an important role in the expression of genes expressed in response to ischemia/reperfusion (I/R) injury. In this report, the activation of NF-,B in rat skeletal muscle during reperfusion following a 4-h ischemic period was studied. NF-,B activation displayed a biphasic pattern, showing peak activities from 30 min to 3 h postperfusion and 6 h to 16 h postperfusion, with a decline to baseline binding activity levels between 3 h and 6 h. Inhibition of NF-,B activation was investigated using proline dithiocarbamate (Pro-DTC). NF-,B binding activity during reperfusion was significantly reduced by intravenous administration of Pro-DTC. Additionally, Pro-DTC resulted in decreased muscle edema and neutrophil activity, with an increased percentage of muscle survival compared with vehicle controls. These results demonstrate that NF-,B is activated during reperfusion in a biphasic manner and that the regulation of the initial phase of NF-,B activation affords physiological protection against a severe ischemic stress. Selective inhibition of NF-,B during early reperfusion may therefore be a therapeutic intervention for I/R injury. 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 534,541, 2001 [source]


Low molecular weight inhibitors of matrix metalloproteinases can enhance the expression of matrix metalloproteinase-2 (gelatinase A) without inhibiting its activation

CANCER, Issue 6 2003
Erika H. M. Kerkvliet Ph.D.
Abstract BACKGROUND In the current study, the authors investigated the effects of synthetic low molecular weight inhibitors of matrix metalloproteinases (MMPs) on the expression and activation of MMP-2 in a three-dimensional tissue system. METHODS Rabbit periosteal explants were cultured with or without various concentrations of the MMP inhibitors CT1166, CT1399, or CT1746, and conditioned media and tissue extracts were analyzed for the expression and activity of MMP-2. RESULTS The data showed that blocking the activity of all MMPs with relatively high inhibitor concentrations completely prevented the conversion of pro-MMP-2 into its active form and that the level of protein was decreased. Selective inhibition of the activity of gelatinases (MMP-2 and MMP-9) by using low inhibitor concentrations, however, induced a higher level of active MMP-2 and increased its expression significantly. CONCLUSIONS The current observations indicate that selective inhibitors of MMPs affect the expression and activity of MMP-2, thus providing clues regarding the differing effects such inhibitors appear to have when applied in vivo. Cancer 2003;97:1582,88. 2003 American Cancer Society. DOI 10.1002/cncr.11193 [source]


Exploring QSAR for Substituted 2-Sulfonyl-Phenyl-Indol Derivatives as Potent and Selective COX-2 Inhibitors Using Different Chemometrics Tools

CHEMICAL BIOLOGY & DRUG DESIGN, Issue 6 2008
Mehdi Khoshneviszadeh
Selective inhibition of cyclooxygenase-2 inhibitors is an important strategy in designing of potent anti-inflammatory compounds with significantly reduced side effects. The present quantitative structure,activity relationship study, attempts to explore the structural and physicochemical requirements of 2-sulfonyl,phenyl,indol derivatives (n = 30) for COX-2 inhibitory activity using chemical, topological, geometrical, and quantum descriptors. Some statistical techniques like stepwise regression, multiple linear regression with factor analysis as the data preprocessing (FA-MLR), principal component regression analysis, and genetic algorithms partial least squares analysis were applied to derive the quantitative structure,activity relationship models. The generated equations were statistically validated using cross-validation and external test set. The quality of equations obtained from stepwise multiple linear regression, FA-MLR, principal component regression analysis and PLS were in the acceptable statistical range. The best multiple linear regression equation obtained from factor analysis (FA-MLR) as the preprocessing step could predict 77.5% of the variance of the cyclooxygenase-2 inhibitory activity whereas that derived from genetic algorithms partial least squares could predict 84.2% of variances. The results of quantitative structure,activity relationship models suggested the importance of lipophilicity, electronegativity, molecular area and steric parameters on the cyclooxygenase-2 inhibitory activity. [source]


Endothelin receptor selectivity in chronic kidney disease: rationale and review of recent evidence

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2009
W. Neuhofer
Abstract Endothelin (ET) is a potent vasoconstrictory peptide with proinflammatory and profibrotic properties that exerts its biological effects through two pharmacologically distinct receptor subtypes, namely ETA and ETB. In addition to its substantial contribution to normal renal function, a large body of evidence suggests that derangement of the renal ET system is involved in the initiation and progression of chronic kidney disease (CKD) in diabetes, hypertension and glomerulonephritis. Thus, the use of ET receptor antagonists (ERAs) may offer potential novel treatment strategies in CKD. Recent literature on the role of the renal ET system in the healthy kidney was reviewed. In addition, an unbiased PubMed search was performed for studies published during the last 5 years that addressed the effects of ERAs in CKD. A particular objective was to extract information regarding whether selective or nonselective ERAs may have therapeutic potential in humans. ET-1 acts primarily as an autocrine or paracrine factor in the kidney. In normal physiology, ET-1 promotes diuresis and natriuresis by local production and action through ETB receptors in the renal medulla. In pathology, ET-1 mediates vasoconstriction, mesangial-cell proliferation, extracellular matrix production and inflammation, effects that are primarily conveyed by ETA receptors. Results obtained in animal models and in humans with the use of ERAs in CKD are encouraging; nevertheless, it is still under debate which receptor subtype should be targeted. According to most studies, selective inhibition of ETA receptors appears superior compared with nonselective ERAs because this approach does not interfere with the natriuretic, antihypertensive and ET clearance effects of ETB receptors. Although preliminary data in humans are promising, the potential role of ERAs in patients with CKD and the question of which receptor subtype should be targeted can only be clarified in randomized clinical trials. [source]


PRECLINICAL STUDY: Ecstasy-induced oxidative stress to adolescent rat brain mitochondria in vivo: influence of monoamine oxidase type A

ADDICTION BIOLOGY, Issue 2 2009
Ema Alves
ABSTRACT The administration of a neurotoxic dose of 3,4-methylenedioxymethamphetamine (MDMA; ,ecstasy') to the rat results in mitochondrial oxidative damage in the central nervous system, namely lipid and protein oxidation and mitochondrial DNA deletions with subsequent impairment of the correspondent protein expression. Although these toxic effects were shown to be prevented by monoamine oxidase B inhibition, the role of monoamine oxidase A (MAO-A) in MDMA-mediated mitochondrial damage remains to be evaluated. Thus, the aim of the present study was to clarify the potential interference of a specific inhibition of MAO-A by clorgyline, on the deleterious effects produced by a binge administration of a neurotoxic dose of MDMA (10 mg MDMA/kg of body weight, intraperitoneally, every 2 hours in a total of four administrations) to an adolescent rat model. The parameters evaluated were mitochondrial lipid peroxidation, protein carbonylation and expression of the respiratory chain protein subunits II of reduced nicotinamide adenine dinucleotide dehydrogenase (NDII) and I of cytochrome oxidase (COXI). Considering that hyperthermia has been shown to contribute to the neurotoxic effects of MDMA, another objective of the present study was to evaluate the body temperature changes mediated by MDMA with a MAO-A selective inhibition by clorgyline. The obtained results demonstrated that the administration of a neurotoxic binge dose of MDMA to an adolescent rat model previously treated with the specific MAO-A inhibitor, clorgyline, resulted in synergistic effects on serotonin- (5-HT) mediated behaviour and body temperature, provoking high mortality. Inhibition of MAO-A by clorgyline administration had no protective effect on MDMA-induced alterations on brain mitochondria (increased lipid peroxidation, protein carbonylation and decrease in the expression of the respiratory chain subunits NDII and COXI), although it aggravated MDMA-induced decrease in the expression of COXI. These results reinforce the notion that the concomitant use of MAO-A inhibitors and MDMA is counter indicated because of the resulting severe synergic toxicity. [source]


Role of the GLT-1 subtype of glutamate transporter in glutamate homeostasis: the GLT-1-preferring inhibitor WAY-855 produces marginal neurotoxicity in the rat hippocampus

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2005
Julie V. Selkirk
Abstract Glutamate is the major excitatory neurotransmitter in the central nervous system and is tightly regulated by cell surface transporters to avoid increases in concentration and associated neurotoxicity. Selective blockers of glutamate transporter subtypes are sparse and so knock-out animals and antisense techniques have been used to study their specific roles. Here we used WAY-855, a GLT-1-preferring blocker, to assess the role of GLT-1 in rat hippocampus. GLT-1 was the most abundant transporter in the hippocampus at the mRNA level. According to [3H]- l -glutamate uptake data, GLT-1 was responsible for approximately 80% of the GLAST-, GLT-1-, and EAAC1-mediated uptake that occurs within dissociated hippocampal tissue, yet when this transporter was preferentially blocked for 120 h with WAY-855 (100 m), no significant neurotoxicity was observed in hippocampal slices. This is in stark contrast to results obtained with TBOA, a broad-spectrum transport blocker, which, at concentrations that caused a similar inhibition of glutamate uptake (10 and 30 m), caused substantial neuronal death when exposed to the slices for 24 h or longer. Likewise, WAY-855, did not significantly exacerbate neurotoxicity associated with simulated ischemia, whereas TBOA did. Finally, intrahippocampal microinjection of WAY-855 (200 and 300 nmol) in vivo resulted in marginal damage compared with TBOA (20 and 200 nmol), which killed the majority of both CA1,4 pyramidal cells and dentate gyrus granule cells. These results indicate that selective inhibition of GLT-1 is insufficient to provoke glutamate build-up, leading to NMDA receptor-mediated neurotoxic effects, and suggest a prominent role of GLAST and/or EAAC1 in extracellular glutamate maintenance. [source]


Synthesis and Comparative Glycosidase Inhibitory Properties of Reducing Castanospermine Analogues

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2005
Paula Daz Prez
Abstract The feasibility of the intramolecular nucleophilic addition of the nitrogen atom in cyclic (thio)carbamates with a pseudo- C -nucleoside structure to the masked carbonyl group in aldose precursors in the synthesis of reducing (i.e., 5-hydroxy)6-oxaindolizidine frameworks is illustrated by the preparation of the 6- epi, 7- epi, 8- epi and 6,8a-di- epi diastereomers of the potent glycosidase inhibitor (+)-castanospermine. In all cases, the increased anomeric effect caused by the high sp2 character of the pseudoamide-type nitrogen atom resulted in the pseudoanomeric hydroxy group being anchored in an axial orientation in aqueous solution, as in the aglycons in ,-glycosides. These analogs of the natural alkaloid showed a higher selectivity in the inhibition of ,-glucosidases. Structure/glycosidase inhibitory activity studies indicated that inversion of any hydroxy group resulted in a dramatic decrease in the inhibition potency, confirming the critical importance of a correct hydroxylation profile. In the case of (+)-8- epi -6-oxacastanospermine derivatives, with a hydroxylation profile with a structural complementarity to that of D -galactose, a moderate but very selective inhibition of ,-galactosidase was observed, supporting the importance of a defined configuration at pseudoanomeric centres for anomeric specificity. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]


Human telomeric G-quadruplex: The current status of telomeric G-quadruplexes as therapeutic targets in human cancer

FEBS JOURNAL, Issue 5 2010
Stephen Neidle
The 3,-ends of human chromosomal DNA terminate in short single-stranded guanine-rich tandem-repeat sequences. In cancer cells, these are associated with the telomere-maintenance enzyme telomerase together with the end-binding protein hPOT1. Small molecules that can compete with these proteins and induce the single-stranded DNA to form quadruplex,ligand complexes are, in effect, able to expose these 3,-ends, which results in the activation of a DNA damage response and selective inhibition of cell growth. Several of these G-quadruplex binding molecules have shown promising anticancer activity in tumour xenograft models, which indicate that the approach may be applicable to the treatment of a wide range of human cancers. This minireview summarizes the available data on these compounds and the challenges posed for drug discovery. [source]


Na,K-ATPase ,2 inhibition alters calcium responses in optic nerve astrocytes

GLIA, Issue 3 2004
April K. Hartford
Abstract Experiments were conducted to test the effect of 1 ,M ouabain, an Na,K-ATPase inhibitor, on capacitative calcium entry (CCE) and calcium responses elicited by ATP in rat optic nerve astrocytes. In the rat, 1 ,M ouabain is sufficient to inhibit the ,2 Na,K-ATPase, but not the ,1. Immortalized astrocytes derived from Na,K-ATPase ,2 homozygous knockout (KO) mice and wild-type (WT) littermates were also used. Cytosolic calcium and sodium concentrations were measured using Fura-2 and SBFI, respectively. The magnitude of the increase in cytosolic calcium concentration during CCE was significantly greater in rat astrocytes exposed to 1 ,M ouabain. To measure calcium release from stores, cells were exposed to ATP in the absence of extracellular calcium. In astrocytes exposed to 1 ,M ouabain, a significantly greater calcium response to ATP was observed. 1 ,M ouabain was shown to inhibit ATP hydrolysis in membrane material containing Na,K-ATPase ,2 and ,1 isoforms (rat muscle) but not in membranes containing only Na,K-ATPase ,1 (rat kidney). In intact astrocytes, 1 ,M ouabain did not alter the cell-wide cytosolic sodium concentration. In mouse Na,K-ATPase ,2 KO astrocytes, the calcium increase during CCE was significantly higher than in WT cells, as was the magnitude of the calcium response to ATP. In KO astrocytes, but not WT, the cytosolic calcium increase during CCE was insensitive to 1 ,M ouabain. Taken together, the results suggest that selective inhibition of the Na,K-ATPase ,2 isoform has the potential to change calcium signaling and CCE. 2003 Wiley-Liss, Inc. [source]


Role of metalloproteins in the clinical management of head and neck squamous cell carcinoma

HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 12 2007
W. Cooper Scurry Jr. MD
Abstract Metalloproteins are a group of catalytic proteins, which play significant roles in cell cycle and death. Matrix metalloproteinases (MMPs) are a family of endopeptidases that are capable of digesting extracellular matrix components. They have been implicated in carcinogenesis and recent developments have been made to use MMPs clinically to predict outcomes. In the future, selective inhibition of these proteins and their regulatory pathways may prove useful in anticancer therapeutics. We present a review article on the clinical applications of metalloproteins in head and neck squamous cell carcinoma (HNSCC). Metalopanstimulin is highlighted as a putative metalloprotein of interest for those treating HNSCC. Expression of particular metalloproteins has correlation with lymph node metastasis, tumor invasiveness, and overall prognosis in HNSCC. 2007 Wiley Periodicals, Inc. Head Neck 2007 [source]


A celecoxib derivative inhibits focal adhesion signaling and induces caspase-8-dependent apoptosis in human acute myeloid leukemia cells

INTERNATIONAL JOURNAL OF CANCER, Issue 1 2008
Isolda Casanova
Abstract Most acute myeloid leukemias (AMLs), including those with c-Kit or FLT3 mutations, show enhanced anchorage independent growth associated with constitutive activation of focal adhesion proteins. Moreover, these alterations increase cell survival, inhibit apoptosis and are associated with poor prognosis and resistance to chemotherapy. Therefore, the induction of apoptosis by selective inhibition of focal adhesion signaling may represent a novel anti-AML therapy. Here, we have evaluated the antitumor effect and the mechanism of action of celecoxib and E7123, a non-Cox-2 inhibitor derivative, in a panel of human AML cell lines and bone marrow mononuclear cells from AML patients. Both compounds induce cell death by inhibiting focal adhesion signaling through p130Cas, FAK and c-Src, leading to caspase-8 dependent apoptosis. This mechanism of action differs from that of classical cytotoxic drugs or of other targeted therapies, and is amenable to rational drug development. Therefore, both drugs could be developed as AML therapeutics; nevertheless, E7123 shows more activity than celecoxib against AML cells, and may not present its Cox-2 dependent cardiovascular toxicity. Finally, our results support the evaluation of celecoxib in AML patients, and the preclinical evaluation of E7123, before its possible clinical testing. 2008 Wiley-Liss, Inc. [source]


Inhibition of osteoblast function in vitro by aminobisphosphonates

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2009
Isabel R. Orriss
Abstract Bisphosphonates are analogues of pyrophosphate, a key physicochemical inhibitor of mineralisation. We examined the direct actions of bisphosphonates on the function of cultured osteoblasts derived from rat calvariae. Treatment with zoledronate, the most potent bisphosphonate studied, reduced osteoblast number at concentrations ,100 nM and was strongly toxic at 10 M, causing a threefold decrease in osteoblast viability after 2 days and a 90% decrease in cell numbers after 14 days. In control osteoblast cultures on plastic, abundant formation of ,trabecular' mineralised bone matrix nodules began after 10 days. Continuous exposure to zoledronate inhibited bone mineralisation at concentrations as low as 10 nM. Pamidronate and clodronate exerted similar effects but at higher doses (,1 and ,10 M, respectively). Short-term or intermittent exposure of osteoblasts to zoledronate and pamidronate (1,10 M) was sufficient to inhibit bone mineralisation by ,85%. Zoledronate but not pamidronate or clodronate also strongly inhibited osteoblast alkaline phosphatase activity at concentrations ,100 nM and soluble collagen production at concentrations ,1 M. We additionally studied the effects of zoledronate on osteoblasts cultured on dentine, a bone-like mineralised substrate, observing similar inhibitory effects, although at concentrations 10,100-fold higher; this shift presumably reflected adsorption of zoledronate to dentine mineral. Thus, zoledronate blocked bone formation in two ways: first, a relatively non-toxic, selective inhibition of mineralisation at concentrations in the low nanomolar range and second, a cytotoxic inhibition of osteoblast growth and function at concentrations ,1 M. Although no data are available on the bisphosphonate concentrations that osteoblasts could be exposed to in vivo, our results are consistent with earlier observations that bisphosphonates may inhibit bone formation. J. Cell. Biochem. 106: 109,118, 2009. 2008 Wiley-Liss, Inc. [source]


Evaluation of extracts of Jatropha curcas and Moringa oleifera in culture media for selective inhibition of saprophytic fungal contaminants

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2009
Grace Mebi Ayanbimpe
Abstract Most fungi occur in nature and utilize simple sources of carbohydrates and nitrogen for growth. Sabouraud's dextrose agar has been an ideal medium for primary isolation of fungi from clinical specimens, but for specimens from nonsterile sites or heavily contaminated ones, it has been necessary to include inhibitory substances such as antibiotics like chloramphenicol (antibacterial) and cycloheximide (antifungal). The problems we have in the our laboratory owing to frequent contamination of cultures and the delays in the procurement of cycloheximide have stimulated a search for alternatives in our local environment to enhance effective laboratory diagnoses of fungal infections. Purified extracts of the leaves and bark of Jatropha curcas and Moringa oleifera (common plants in our locality) were tested against clinical isolates of fungi at various concentrations to determine the minimum inhibitory concentration at which common fungal contaminants are inhibited, without affecting the growth of the pathogenic fungi sought for. At a concentration of 0.75,mg,ml,1 contaminants were totally inhibited by the leaf extracts. The bark extracts did not inhibit any fungus even at higher concentrations. From the results it was evident that the leaf extracts of both plants have potentials for use as inhibitory substances in culture media against contaminant fungi including Aspergillus spp., Penicillium spp., etc. J. curcas and M. oleifera are very common plants in our locality. They can be obtained at almost no cost and at any time needed. The benefits of these findings to mycology laboratories in a developing country are enormous. J. Clin. Lab. Anal. 23:161,164, 2009. 2009 Wiley-Liss, Inc. [source]


Role of interleukin-18 in the development of acute pulmonary injury induced by intestinal ischemia/reperfusion and its possible mechanism

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 2 2007
Yong-jie Yang
Abstract Background and Aims:, Lung injury is an important target for the systemic inflammatory response associated with intestinal ischemia/reperfusion (I/R). In the present study, the role of interleukin (IL)-18 in the development of acute pulmonary injury induced by intestinal I/R and its possible mechanism in relation to the increased activity of inducible nitric oxide synthase and tumor necrosis factor (TNF)-, were investigated. Methods:, Mice were randomly divided into three groups: normal control group without operation; sham group with sham operation; and I/R group in which mice underwent superior mesenteric artery occlusion for 30 min followed by reperfusion for 3 h. Each group received pretreatment with exogenous IL-18, anti-IL-18 neutralizing antibody or L-NIL, the selective inhibitor of inducible nitric oxide synthase, 30 min before ischemia. The expression of TNF-, was detected by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). Lung injury was evaluated by means of Evans blue dye (EBD) concentration, myeloperoxidase (MPO) activity and morphological analysis. Results:, The experimental results showed that both in the sham-operated and I/R groups of animals, pretreatment with exogenous IL-18 clearly enhanced pulmonary MPO activity, microvascular leakage and the expression of TNF-, mRNA and protein. In contrast, IL-18 did not increase the TNF-, level and degree of lung injury, although it clearly enhanced the pulmonary MPO activity in normal animals. Meanwhile, IL-18 antibody given prior to ischemia led to a reduction in the sequestration of neutrophils, extravasation of EBD and downregulation of the serum level of TNF-, in the I/R group of animals. In addition, selective inhibition of inducible nitric oxide synthase (iNOS) that inhibited plasma extravasation and pulmonary injury without affecting the MPO activity could be demonstrated in all treated animals. Conclusions:, These data suggested a role of IL-18 in the activation and sequestration of neutrophils in lungs. Our results were consistent with the hypothesis that increased sequestration of neutrophils and microvascular leakage might, respectively, relate to the increased IL-18 level and the elevation of TNF-,/iNOS activity, and these two aspects might synergically contribute to intestinal I/R-induced pulmonary dysfunction. [source]


Cholesterol-dependent modulation of dendrite outgrowth and microtubule stability in cultured neurons

JOURNAL OF NEUROCHEMISTRY, Issue 1 2002
Qi-Wen Fan
Abstract Microtubule-associated protein 2 (MAP2) is a neuron-specific cytoskeletal protein enriched in dendrites and cell bodies. MAP2 regulates microtubule stability in a phosphorylation-dependent manner, which has been implicated in dendrite outgrowth and branching. We have previously reported that cholesterol deficiency causes tau phosphorylation and microtubule depolymerization in axons (Fan et al. 2001). To investigate whether cholesterol also modulates microtubule stability in dendrites by modulating MAP2 phosphorylation, we examined the effect of compactin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and TU-2078 (TU), a squalene epoxidase inhibitor, on these parameters using cultured neurons. We have found that cholesterol deficiency induced by compactin and TU, inhibited dendrite outgrowth, but not of axons, and attenuated axonal branching. Dephosphorylation of MAP2 and microtubule depolymerization accompanied these alterations. The amount of protein phosphatase 2 A (PP2A) and its activity in association with microtubules were decreased, while those unbound to microtubules were increased. The synthesized ceramide levels and the total ceramide content were increased in these cholesterol-deficient neurons. These alterations caused by compactin were prevented by concurrent treatment of cultured neurons with ,-migrating very-low-density lipoproteins (,-VLDL) or cholesterol. Taken together, we propose that cholesterol-deficiency causes a selective inhibition of dendrite outgrowth due to the decreased stability of microtubules as a result of inhibition of MAP2 phosphorylation. [source]


PGE2 and IL-6 production by fibroblasts in response to titanium wear debris particles is mediated through a Cox-2 dependent pathway

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2004
Susan V. Bukata
Aseptic loosening of orthopaedic implants is precipitated by wear debris-induced osteolysis. Central to this process are the pro-inflammatory mediators that are produced in response to wear by the fibroblastic cells, which comprise the majority of periprosthetic membranes. Since this pro-inflammatory cascade is mediated by a plethora of factors with redundant functions, it is imperative to establish a hierarchy. Two well-known fibroblast derived pro-inflammatory factors that stimulate wear debris-induced osteoclastic resorption are prostaglandin E2 (PGE2) and IL-6. However, their relationship to each other in this process is poorly defined. Here we show immunohistochemistry of retrieval membranes indicating that COX-2 is the principal cyclooxygenase responsible for PGE2 production in fibroblasts around failed implants. We also performed in vitro experiments with fibroblasts derived from wild-type (WT), COX-1 (,/,) and COX-2 (,/,) mice, which demonstrated that COX-2 is required for Ti wear debris-induced PGE2 production. Interestingly, COX-2 was also required for IL-6 production in these assays, which could be rescued by the addition of exogenous PGE2 (10,6 M). Pharmacology studies that utilized the COX-1 selective inhibitor SC 560, the COX-2 selective inhibitor celecoxib, and the nonselective COX inhibitor indomethacin confirmed these results. Taken together, these results indicate that selective inhibition of prostaglandin signaling could favorably impact aseptic loosening beyond its direct effects on PGE2 synthesis, in that it inhibits downstream pro-inflammatory/pro-osteoclastic cytokine production. 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source]


Role of systemic and local administration of selective inhibitors of cyclo-oxygenase 1 and 2 in an experimental model of periodontal disease in rats

JOURNAL OF PERIODONTAL RESEARCH, Issue 2 2009
C. M. Queiroz-Junior
Background and Objective:, Periodontal disease is an inflammatory condition of tooth-supporting tissues. Arachidonic acid metabolites have been implicated in development of periodontal disease, especially those derived from the cyclo-oxygenase (COX) pathway. This study investigated the role of inhibitors of cyclo-oxygenases (COX-1 and COX-2) in a model of periodontal disease in rats. Material and Methods:, A ligature was placed around the molar of rats. Losses of fiber attachment and of alveolar bone were measured morphometrically in histologically prepared sections. Infiltration of cells into gingival tissue surrounding the ligated tooth was also determined. Results:, Systemic and local administration of non-selective and selective COX-2 inhibitors, preventively, resulted in significant reduction of the losses of fiber attachment and alveolar bone, as well as decreased leukocyte numbers in gingival tissue. Preventive selective inhibition of COX-1 was as effective as COX-2 inhibition in reducing local fiber attachment loss and cell migration, but did not prevent alveolar bone loss. Conclusion:, Our results provide evidence for participation of COX-1 and COX-2 in early stages of periodontal disease in rats. Furthermore, local administration of COX inhibitors reduced the signs of periodontal disease to the same extent as systemic treatment. Therapeutic approaches incorporating locally delivered anti-inflammatory drugs could be of benefit for patients suffering from periodontal disease. [source]


Effects of furocoumarins from Cachrys trifida on some macrophage functions

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 8 2001
M. J. Abad
Phytochemical and biological studies aimed at the discovery and development of novel antiinflammatory agents from natural sources have been conducted in our laboratory for a number of years. In this communication, three naturally occurring furocoumarins (imperatorin, isoimperatorin and prantschimgin) were evaluated as potential inhibitors of some macrophage functions involved in the inflammatory process. These furocoumarins have been tested in two experimental systems: ionophore-stimulated mouse peritoneal macrophages serve as a source of cyclooxygenase-1 and 5-lipoxygenase, and mouse peritoneal macrophages stimulated with E. coli lipopolysaccharide are the means of testing for anti-cyclooxygenase-2 and nitric-oxide-synthase activity. All above-mentioned furocoumarins showed significant effect on 5-lipoxygenase (leukotriene C4) with IC50 values of < 15 ,M. Imperatorin and isoimperatorin exhibited strong-to-medium inhibition on cyclooxygenase-1- and cyclooxygenase-2-catalysed prostaglandin E2 release, with inhibition percentages similar to those of the reference drugs, indometacin and nimesulide, respectively. Of the three furocoumarins, only imperatorin caused a significant reduction of nitric oxide generation. Imperatorin and isoimperatorin can be classified as dual inhibitors, since it was evident that both cyclooxygenase and lipoxygenase pathways of arachidonate metabolism were inhibited by these compounds. However, selective inhibition of the 5-lipoxygenase pathway is suggested to be the primary target of action of prantschimgin. [source]


Differential Central NOS-NO Signaling Underlies Clonidine Exacerbation of Ethanol-Evoked Behavioral Impairment

ALCOHOLISM, Issue 3 2010
Tara S. Bender
Background:, The molecular mechanisms that underlie clonidine exacerbation of behavioral impairment caused by ethanol are not fully known. We tested the hypothesis that nitric oxide synthase (NOS)-derived nitric oxide (NO) signaling in the locus coeruleus (LC) is implicated in this phenomenon. Methods:, Male Sprague,Dawley rats with intracisternal (i.c.) and jugular vein cannulae implanted 6 days earlier were tested for drug-induced behavioral impairment. The latter was assessed as the duration of loss of righting reflex (LORR) and rotorod performance every 15 minutes until the rat recovered to the baseline walk criterion (180 seconds). In a separate cohort, we measured p-neuronal NOS (nNOS), p-endothelial NOS (eNOS), and p-ERK1/2 in the LC following drug treatment, vehicle, or NOS inhibitor. Results:, Rats that received clonidine [60 Ig/kg, i.v. (intravenous)] followed by ethanol (1 or 1.5 g/kg, i.v.) exhibited synergistic impairment of rotorod performance. Intracisternal pretreatment with nonselective NOS inhibitor N, -nitro- l -arginine methyl ester (l -NAME, 0.5 mg) or selective nNOS inhibitor N -propyl- l -arginine (1 ,g) exacerbated the impairment of rotorod performance caused by clonidine,ethanol combination. Exacerbation of behavioral impairment was caused by l -NAME enhancement of the effect of ethanol, not clonidine. l -NAME did not influence blood ethanol levels; thus, the interaction was pharmacodynamic. LORR caused by clonidine (60 ,g/kg, i.v.),ethanol (1 g/kg, i.v.) combination was abolished by selective inhibition of central eNOS (l -NIO, 10 ,g i.c.) but not by nNOS inhibition under the same conditions. Western blot analyses complemented the pharmacological evidence by demonstrating that clonidine,ethanol combination inhibits phosphorylation (activation) of nNOS (p-nNOS) and increases the level of phosphorylated eNOS (p-eNOS) in the LC; the change in p-nNOS was paralleled by similar change in LC p-ERK1/2. NOS inhibitors alone did not affect the level of nitrate/nitrite, p-nNOS, p-eNOS, or p-ERK1/2 in the LC. Conclusions:, Alterations in NOS-derived NO in the LC underlie clonidine,ethanol induced behavioral impairment. A decrease in nNOS activity, due at least partly to a reduction in nNOS phosphorylation, mediates rotorod impairment, while enhanced eNOS activity contributes to LORR, elicited by clonidine,ethanol combination. [source]


First cloning and functional characterization of a melatonin receptor in fish brain: a novel one?

JOURNAL OF PINEAL RESEARCH, Issue 2 2002
Pascaline Gaildrat
Melatonin, a neuroendocrine transducer of photoperiod, influences a number of physiological functions and behaviors through specific seven transmembrane domains receptors. We report here the first full-length cloning and functional characterization of a melatonin receptor (P2.6) in a fish, the pike (Teleost). P2.6 encodes a protein that is ,80% identical to melatonin receptors previously isolated partially in non-mammals and classified as members of the Mel1b subtype; but, it shares only 61% identity with the full-length human Mel1b melatonin receptor (hMT2). Expression of P2.6 results in ligand binding characteristics similar to that described for endogenous melatonin receptors. Selective antagonists of the hMT2 (4-phenyl-2-propionamidotetraline and luzindole) were poor competitors of 2-[125I]iodomelatonin binding to the recombinant receptor. In Chinese hamster ovary cells expressing both the cystic fibrosis transmembrane conductance regulator chloride channel and P2.6 receptor, melatonin counteracted the forskolin induced activation of the channel. The results are best explained by a selective inhibition of the adenylyl cyclase. By reverse transcription-polymerase chain reaction, P2.6 mRNA appeared expressed in the optic tectum and, to lesser extent, in the retina and pituitary. In conclusion, these results, together with those of a phylogenetic analysis, suggest that P2.6 might belong to a distinct subtype group within the vertebrate melatonin receptor family. [source]


Targeted inhibition of the serotonin 5HT2A receptor improves coronary patency in an in vivo model of recurrent thrombosis

JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2 2010
K. PRZYKLENK
Summary.,Background: Release of serotonin and activation of serotonin 5HT2A receptors on platelet surfaces is a potent augmentative stimulus for platelet aggregation. However, earlier-generation serotonin receptor antagonists were not successfully exploited as antiplatelet agents, possibly owing to their lack of specificity for the 5HT2A receptor subtype. Objective: To assess whether targeted inhibition of the serotonin 5HT2A receptor attenuates recurrent thrombosis and improves coronary patency in an in vivo canine model mimicking unstable angina. Methods: In protocol 1, anesthetized dogs were pretreated with a novel, selective inverse agonist of the 5HT2A receptor (APD791) or saline. Recurrent coronary thrombosis was then initiated by coronary artery injury + stenosis, and coronary patency was monitored for 3 h. Protocol 2 was similar, except that: (i) treatment with APD791 or saline was begun 1 h after the onset of recurrent thrombosis; (ii) template bleeding time was measured; and (iii) blood samples were obtained for in vitro flow cytometric assessment of platelet responsiveness to serotonin. Results: APD791 attenuated recurrent thrombosis, irrespective of the time of treatment: in both protocols, flow,time area (index of coronary patency; normalized to baseline coronary flow) averaged 58,59% (P < 0.01) following administration of APD791 vs. 21,28% in saline controls. Moreover, the in vivo antithrombotic effect of APD791 was not accompanied by increased bleeding, but was associated with significant and selective inhibition of serotonin-mediated platelet activation. Conclusion: 5HT2A receptor inhibition with APD791, even when initiated after the onset of recurrent thrombosis, improves coronary patency in the in vivo canine model. [source]


Pharmacological properties and clinical efficacy of a recently licensed systemic antifungal, caspofungin

MYCOSES, Issue 4 2005
Georg Maschmeyer
Summary Caspofungin, a semisynthetic derivative of the pneumocandin B0, is the first licensed compound of a new class of antifungal agents, the echinocandins. It attacks the fungal cell by selective inhibition of the beta-(1,3)- d -glucan synthase, which is not present in mammalian cells. In vitro studies have indicated a potent fungicidal effect on Candida species, and in vivo studies in immunocompromised animals with invasive candidiasis demonstrated a favourable outcome. In randomized clinical trials in patients with oropharyngeal/oesophageal and invasive candidiasis, caspofungin was at least as effective as amphotericin B deoxycholate, yet showed a significantly superior safety profile. Of patients with invasive aspergillosis refractory to or intolerant of other antifungal agents, 45% showed a partial or complete response to caspofungin given as a salvage treatment. Also, it demonstrated comparable clinical efficacy but superior tolerability in the empirical antifungal therapy in neutropenic patients compared with liposomal amphothericin B. Caspofungin has an excellent tolerability and a low potential for drug interactions. Thus, caspofungin represents an interesting and clinically valuable new antifungal drug that broadens the available therapeutic armamentarium for the treatment of invasive fungal infections. [source]


Mycophenolate mofetil without antibody induction in cadaver vs. living donor pediatric renal transplantation

PEDIATRIC TRANSPLANTATION, Issue 2 2003
O. Ojogho
Abstract: Mycophenolate mofetil (MMF) is a new immunosuppressive agent that blocks de novo purine synthesis in T and B lymphocytes via a potent selective inhibition of inosine monophosphate dehydrogenase. MMF has been shown to significantly reduce the incidence of acute rejection in both adult and pediatric renal transplantation. The impact of MMF on routine antibody induction therapy in pediatric renal transplantation has not been defined. Remarkably, a recent North American Pediatric Transplant Cooperative Study concluded that T-cell antibody induction therapy was deleterious for patients who received MMF. Our study examines the use of MMF in an evolving immunosuppressive strategy to avoid antibody induction in both living (LD) and cadaver (CAD) donor pediatric renal transplantation. We retrospectively analyzed the records of 43 pediatric renal transplants that received MMF-based triple therapy without antibody induction therapy between November 1996 and April 2000. We compared CAD (n = 17) with LD (n = 26). The two groups were similar demographically except that CAD had significantly younger donors than LD, 26.1 13.7 vs. 36.2 9.2 yr (p = 0.006). All the patients received MMF at 600 mg/m2/b.i.d. (maximum dose of 2 g/d) and prednisone with cyclosporine (86%) or tacrolimus (14%). Mean follow-up was >36 months for each group. Acute rejection rate at 6 months was 11.8% (CAD) vs. 15.4% (LD) (p = 0.999) and at 1 yr was 23.5% (CAD) vs. 26.9% (LD) (p = 0.999). Mean estimated glomerular filtration rate (ml/min/1.73 m2) at 6 months was 73.3 15.3 (CAD) vs. 87.6 24.2 (LD) (p = 0.068). Patient survival at 1, 2, and 3 yr was 100, 100, and 100% for CAD vs. 100, 96, and 96% for LD, respectively. Graft survival at 1, 2, and 3 yr was 100, 100, and 94% for CAD vs. 96, 88, and 71% for LD, respectively. Graft loss in CAD was because of chronic rejection (n = 2) while in LD it was because of non-compliance (n = 6), post-transplant lymphoproliferative disorder (n = 1), and sepsis (n = 1). In conclusion, MMF without antibody induction in both CAD and LD pediatric renal transplantation provides statistically similar and effective prophylaxis against acute rejection at 6 months and 1 yr post-transplant. The short-term patient and graft survival rates are excellent, however, non-compliance remains a serious challenge to long-term graft survival. Additional controlled studies are needed to define the role of MMF without antibody induction therapy in pediatric renal transplantation. [source]


Mizoribine: Mode of action and effects in clinical use

PEDIATRICS INTERNATIONAL, Issue 2 2002
Shumpei Yokota
Abstract Mizoribine is a new immunosuppressive drug and was authorized by the Japanese Government in 1984. The strong immunosuppressive activity of mizoribine was already demonstrated in various animal models, in renal transplantation and in steriod-resistant nephrotic syndrome. Recently, the remarkable clinical advantages of an imidazole for adults with rheumatoid arthritis, lupus nephritis and other rheumatic diseases were reported. Mizoribine is an imidazole nucleoside and the metabolites, MZ-5-P, exerts its activity through selective inhibition of inosine monophosphate synthetase and guanosine monophosphate synthetase, resulting in the complete inhibition of guanine nucleotide synthesis without incorporation into nucleotides. Thus, mizoribine is superior to azathioprine, in that it may not cause damages to normal cells and normal nucleic acid. [source]