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Biomedical subjects

M J Alcaraz

Publications and source records attributed to M J Alcaraz.

At least 19 recordsLinked to original sources
PubMed2001

Heme oxygenase-1 induction by nitric oxide in RAW 264.7 macrophages is upregulated by a cyclo-oxygenase-2 inhibitor.

Unstimulated RAW 264.7 macrophages express negligible heme oxygenase-1 (HO-1) protein but incubation with the nitric oxide (NO) donor spermine nonoate (SPNO) induced HO-1 and weakly cyclo-oxygenase-2 (COX-2) protein. This effect was potentiated by coincubation with the COX-2 selective inhibitor, SC58125. Cells incubated with SPNO showed a strong increase in HO-1 mRNA levels after 4 h with a significant potentiation in the presence of SC58125, which did not modify HO-1 mRNA stability. The induction of HO-1 by NO and its potentiation by anti-inflammatory agents may play a role in inflammatory and immune responses.

Animals↗
PubMed2001

Solid-phase synthesis and inhibitory effects of some pyrido[1,2-c]pyrimidine derivatives on leukocyte formations and experimental inflammation.

A number of pyrido[1,2-c]pyrimidines bearing a nitrogen, oxygen, or sulfur functionality at C-1 were synthesized on solid-phase using the iminophosphorane methodology and tested for their effects on leukocyte functions in vitro and antiinflammatory activity. Compound 5c was found to be a strong scavenger of superoxide anion and an inhibitor of chemiluminescence induced by 12-O-tetradecanoylphorbol 13-acetate in human neutrophils. These pyrido[1,2-c]pyrimidines inhibited the generation of PGE(2) by COX-2 in RAW 264.7 macrophages stimulated with lipopolysaccharide. Compounds 7, 5f, 6, and 8 inhibited enzyme activity, whereas the remaining compounds also acted on the induction phase. In addition, 5a-f, 6, and 7 administered p.o. at a dose of 20 mg/kg showed antiinflammatory activity in the carrageenan mouse paw edema model, where they inhibited PGE(2) levels in inflamed paws without affecting the content of this eicosanoid in stomachs. Inhibition of PGE(2) production and superoxide scavenging may participate in the mechanism of the antiinflammatory action of these pyrido[1,2-c]pyrimidine derivatives.

Animals↗
PubMed2001

4-dimethylamino-3',4'-dimethoxychalcone downregulates iNOS expression and exerts anti-inflammatory effects.

Reactive oxygen and nitrogen species contribute to the pathophysiology of inflammatory conditions. We have studied the effects of a novel superoxide scavenger, 4-dimethylamino-3', 4'-dimethoxychalcone (CH11) in macrophages and in vivo. CH11 has been shown to inhibit the chemiluminescence induced by zymosan in mouse peritoneal macrophages and the cytotoxic effects of superoxide. In the same cells, the modulation by superoxide of nitric oxide (NO) production in response to zymosan was investigated. CH11 was more effective than the membrane-permeable scavenger Tiron for inhibition of inducible nitric oxide synthase (iNOS) protein expression and nitrite production. We have shown that CH11 inhibited chemiluminescence in vivo, as well as cell migration, and eicosanoid and tumor necrosis factor-alpha (TNF-alpha) levels in the mouse air pouch injected with zymosan. This chalcone derivative also exerted anti-inflammatory effects in the carrageenan paw oedema.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed2001

Effect of imidazo[1,2-a]pyrimidine derivatives on leukocyte function.

OBJECTIVE AND DESIGN: A series of six imidazo[1,2-a]pyrimidine (IP) derivatives were evaluated for their effects on leukocyte functions in vitro as well as on the inflammatory response induced by zymosan in the mouse air pouch. MATERIALS AND SUBJECTS: Human neutrophils and murine peritoneal macrophages were used for in vitro assays. Mouse air pouch was performed in Swiss mice. TREATMENT: Test compounds were incubated with either human neutrophils or mouse peritoneal macrophages at concentrations not showing cytotoxic effects. For in vivo experiments, IPs were injected into the air pouch. METHODS: Elastase and myeloperoxidase release, superoxide generation and LTB4 production were assayed in human neutrophils treated with different stimuli. Mouse peritoneal macrophages were stimulated with lipopolysaccharide (LPS), followed by determination of nitrite and PGE2 levels in supernatants. Zymosan was injected into six days-old mouse air pouches. Dunnett's t-test was employed for statistical analysis. RESULTS: All IPs inhibited human neutrophil degranulation with IC50 values in the microM range. IP-1, IP-2 and IP-5 also decreased superoxide generation. In LPS-stimulated macrophages, IP-4 and IP-6 inhibited nitrite production with a moderate reduction in PGE2 generation. In addition, these two compounds at 100 nmol/pouch inhibited leukocyte migration and LTB4 levels in the exudate of the mouse air pouch. CONCLUSIONS: Imidazo[1,2-a]pyrimidines are a class of compounds with antiinflammatory potential.

Animals↗
PubMed2001

Inhibition of 5-lipoxygenase activity by the natural anti-inflammatory compound aethiopinone.

OBJECTIVE AND DESIGN: We have investigated the mechanisms of action of aethiopinone, an anti-inflammatory compound from Salvia aethiopis L. roots. MATERIAL AND SUBJECTS: Human neutrophils from healthy volunteers and murine peritoneal macrophages. Swiss mice were randomly divided into groups of six animals. TREATMENT: Test compounds were applied topically in the mouse ear oedema test. In the air pouch, mice received aethiopinone (0.001-0.5 pmol/pouch or 12.5-50 mg/kg p.o.). METHODS: LTB4 production was assayed in human neutrophils and COX-2 and iNOS activities in murine macrophages. Air pouches were induced subcutaneously in mice and injected with zymosan on the day six. Mouse ear oedema was induced by arachidonic acid. Dunnett's t-test was employed for statistical analysis. RESULTS: We have observed potent inhibitory effects on human neutrophil LTB4 production without effects on COX or NOS activities. Aethiopinone is an in vitro inhibitor of 5-LO from human neutrophils (IC50 = 0.11 microM). In addition, aethiopinone reduced leukocyte accumulation and showed in vivo inhibitory activity on this enzyme. CONCLUSIONS: Our results indicate that inhibition of 5-LO could participate in the anti-inflammatory properties of this natural product.

Animals↗
PubMed2001

[Lymphadenomegaly in patients with chronic liver disease].

Abdominal lymphadenomegaly is a frequent ultrasonographic finding in patients with chronic liver disease. Its clinical significance is not well understood. The aim of this study was to determine the relationship between this finding and several characteristics of liver disease in 44 patients with chronic liver disease (79.5% due to hepatitis C virus). To do this, all patients underwent simultaneous liver biopsy and abdominal ultrasonography, in which the number and localization of the enlarged abdominal lymph nodes were confirmed. Viral load in patients with chronic hepatitis C virus infection was determined. No significant differences were found in serum hepatitis C RNA concentrations between patients who presented lymphadenomegaly and those who did not. However, the presence of lymphadenomegaly was associated with greater histological activity. If this finding were confirmed in studies with larger samples, the presence of ultrasonographically-detected enlarged abdominal lymph nodes in patients with chronic liver disease due to hepatitis C virus infection would indicate more severe histological lesions.

Abdomen↗
PubMed2001

Inhibition of leukocyte functions by the alkaloid isaindigotone from Isatis indigotica and some new synthetic derivatives.

The alkaloid isaindigotone (1a) and seven derivatives have been synthesized to study their influence on several leukocyte functions and the generation of inflammatory mediators. Isaindigotone (1a) was found to be a scavenger of superoxide generated either by the hypoxanthine/xanthine oxidase system or stimulated human neutrophils. Isaindigotone (1a) and its acetylated derivative (1b) also inhibited 5-lipoxygenase activity and leukotriene B(4) production in these cells, whereas none of the compounds affected degranulation. In RAW 264.7 macrophages stimulated with lipopolysaccharide, synthetic derivatives exerted higher inhibitory effects on prostaglandin E(2) (PGE(2)) and nitric oxide (NO) generation when compared with (1a). The presence of an acetoxyl group at C-4' favors the inhibition of NO and PGE(2) production, whereas the fluoro substituent at C-4' or the absence of substituents on the aromatic ring of the benzylidene unit improves the inhibition of PGE(2). Thus, this series of compounds can attenuate the production of mediators relevant to the inflammatory response.

Alkaloids↗
PubMed2001

Modulation of haem oxygenase-1 expression by nitric oxide and leukotrienes in zymosan-activated macrophages.

Phagocytosis of unopsonized zymosan by RAW 264.7 macrophages upregulated protein expression of haem oxygenase-1 (HO-1), inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2) in a time- and concentration-dependent manner. In the presence of zymosan, exogenous prostaglandin E(2) (PGE(2)) did not exert significant effects on the expression of these three enzymes. In contrast, exogenous leukotriene B(4) (LTB(4)) and LTC(4) in the nanomolar range inhibited HO-1 and iNOS expression, as well as nitrite accumulation. The COX inhibitors indomethacin and NS398 weakly inhibited HO-1 expression but had no effect on iNOS and COX-2 expression or nitrite. In contrast, the 5-lipoxygenase (5-LO) inhibitor ZM 230,487 significantly decreased HO-1, iNOS and nitrite, which were not affected by zileuton. Dexamethasone showed an inhibitory effect on HO-1 expression induced by zymosan. ZM 230,487 but not zileuton, inhibited the shift due to nuclear factor-kappaB (NF-kappaB), whereas they did not modify activator protein-1 (AP-1) binding. Our results suggest that inhibition of NF-kappaB binding could mediate the effects of ZM 230,487 on the modulation of HO-1 and iNOS protein expression. NOS inhibition by L-N(G)-nitroarginine methyl ester (L-NAME) or 1400 W abolished nitrite production and strongly reduced HO-1 expression. These results show an induction of HO-1 protein expression by zymosan phagocytosis in macrophages, with a positive modulatory role for endogenous NO and a negative regulation by exogenous LTs, likely dependent on the reduction of iNOS expression and NO production.

Amidines↗
PubMed2001

Inhibition of acute and chronic inflammatory responses by the hydroxybenzoquinonic derivative rapanone.

Rapanone (2,5-dihydroxy-3-tridecyl-1,4-benzoquinone), a natural compound isolated from Myrsine guianensis growing in the Andean highlands of Colombia, was studied in different in vitro and in vivo models as a potential antioxidant and anti-inflammatory drug. Rapanone showed a mild anti-lipoperoxidative profile in rat liver microsomes and inhibited potently degranulation (IC(50) of 9.8 microM) and superoxide chemiluminescence (IC(50) of 3.0 microM) in human neutrophils. In addition, rapanone is a selective and potent human synovial PLA(2) inhibitor (IC(50) of 2.6 microM). In vivo experiments using the carrageenan paw oedema and the zymosan air pouch model in mice as well as the adjuvant arthritis model in rats have proved that rapanone is very efficient in controlling the inflammatory process by different administration routes.

Animals↗
PubMed2001

Effect of some hexahydroimidazo[1,2-c]pyrimidines in inflammatory responses involving leucocytes and macrophages.

We have studied the effects of some hexahydroimidazo[1,2-c]pyrimidine derivatives (HIPs) on leucocyte functions in-vitro and we have assayed the anti-inflammatory activity of these compounds in two models of inflammation. All HIPs inhibited the human neutrophil degranulation process and superoxide generation at concentrations in the microM range. In mouse peritoneal macrophages stimulated with lipopolysaccharide, HIP-4 and HIP-5 inhibited nitrite production without affecting prostaglandin E2 (PGE2) accumulation. HIP-4 was also active in the zymosan-injected mouse air pouch model (at 100 nmol/pouch), with significant reductions in leucocyte migration and PGE2 and leukotriene B4 levels in the air pouch exudate. To confirm the anti-inflammatory effects of this compound, we tested HIP-4 orally (10-40 mg kg(-1)) on carrageenan mouse-paw oedema where it exerted a dose-dependent inhibition of paw swelling with significant reductions of myeloperoxidase and elastase activity and PGE2 levels in paw homogenates. This study demonstrates that some HIPs inhibit leucocyte functions and one of these derivatives (HIP-4) shows anti-inflammatory activity when administered by the oral route, which can be related to inhibition of leucocyte migration.

Animals↗
PubMed2000

An anti-inflammatory ditriazine inhibiting leukocyte functions and expression of inducible nitric oxide synthase and cyclo-oxygenase-2.

A ditriazine derivative (4,10-dichloropyrido[5,6:4,5]thieno[3,2-d':3, 2-d]-1,2,3-ditriazine (DTD)) inhibited neutrophil functions, including degranulation, superoxide generation, and leukotriene B(4) production, without any effect on 5-lipoxygenase activity. This compound reduced nitric oxide (NO) and prostaglandin E(2) production in mouse peritoneal macrophages stimulated with lipopolysaccharide, whereas no influence on the activity of inducible NO synthase, cyclo-oxygenase-2 or cyclo-oxygenase-1 was observed. DTD significantly reduced mouse paw oedema induced by carrageenan and also markedly reduced NO and prostaglandin E(2) levels in exudates from 24-h zymosan-stimulated mouse air pouch. Western blot analysis showed that DTD reduced the expression of inducible NO synthase and cyclo-oxygenase-2. Our results indicate that DTD exerts anti-inflammatory effects related to the inhibition of neutrophil functions and of NO and prostaglandin E(2) production, which could be due to a decreased expression of inducible NO synthase and cyclo-oxygenase-2.

Animals↗
PubMed2000

Effects of some isoxazolpyrimidine derivatives on nitric oxide and eicosanoid biosynthesis.

The inhibitory effect of some isoxazolpyrimidine derivatives on iNOS and COX-2 endotoxin induction in mouse peritoneal macrophages has been studied. Three of these compounds inhibited nitrite and PGE2 accumulation in a concentration dependent-manner at microM range. None of these active compounds affected iNOS, COX-2, COX-1 or PLA2 activities, although some reduced iNOS or COX-2 expression. Besides, no effect was observed on human neutrophil inflammatory responses (LTB4 biosynthesis and superoxide or elastase release). Active compounds were assayed by oral administration in the mouse air pouch model, where they inhibited nitrite accumulation without affecting PGE2 levels or leukocyte migration.

Animals↗
PubMed2000

Co-regulation between cyclo-oxygenase-2 and inducible nitric oxide synthase expression in the time-course of murine inflammation.

Many in vitro studies have used cell cultures to focus on the relationships between cyclo-oxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) isoforms. We have investigated the time-course of regulation and the role of COX-2 and iNOS in a model of experimental inflammation in mice, the air pouch injected with zymosan. This study demonstrates that there is an early acute phase (4 h) mediated mainly by eicosanoids, with high levels of prostaglandin E2 (PGE2) produced by cyclo-oxygenase-1. In addition, in the later phase (from 12 h) there is a participation of nitric oxide (NO) and PGE2 accompanied by co-induction of both iNOS and COX-2. These enzymes were detected in migrating leukocytes as well as in macrophages lining the air pouch. Administration of NS398 or indomethacin inhibited PGE2 levels and COX activity, but also nitrite levels and iNOS activity, which was accompanied by a reduction in iNOS expression. Aminoguanidine inhibited nitrite levels and iNOS activity in addition to exerting inhibitory effects on the COX pathway. Treatment of animals with dexamethasone reduced nitrite and PGE2 concentrations in air pouch exudates, as well as iNOS and COX-2 expression in migrating cells. Our results indicate that PGE2 and NO may play in vivo mutual modulatory roles in the inflammatory response caused by zymosan injection into the mouse air pouch, a suitable model to study drugs acting on those pathways.

Animals↗
PubMed2000

New pyridinium alkaloids from a marine sponge of the genus Spongia with a human phospholipase A(2) inhibitor profile.

Four new bioactive pyridinium alkaloids, named spongidines A-D (5-8), have been isolated from a Vanuatu sponge of the genus Spongia, together with known petrosaspongiolides D (1) and G (2). Compounds 3 and 4 are 21-hydroxy derivatives of petrosaspongiolides K and P. Structure elucidation was accomplished through extensive 2D NMR experiments (COSY, ROESY, HMBC, HMQC) and IR, UV, and FABMS data. All compounds significantly inhibited human synovial phospholipase A(2) (PLA(2)) at 10 microM, with an IC(50) value of 5.8 microM for compound 4, which is the most potent inhibitor, with a higher selectivity toward this enzyme than the reference inhibitor manoalide. Pyridinium alkaloids (5-8) mainly inhibited human synovial PLA(2). Compound 8, which contains a sulfonic acid group, is the most interesting inhibitor.

Alkaloids↗
PubMed2000

Enhanced expression of haem oxygenase-1 by nitric oxide and antiinflammatory drugs in NIH 3T3 fibroblasts.

1. Haem oxygenase-1 (HO-1) can exert protective effects against oxidative stress and inflammation. Fibroblasts participate in inflammatory responses where they produce high levels of prostaglandins (PGs) and nitric oxide (NO). However, little is known of the presence of HO-1 in these cells and the possible interactions among these pathways. Incubation of cells with NO donors, spermine nonoate (SPNO) and S-nitroso-N-acetylpenicillamine (SNAP), induced a dose- and time-dependent expression of HO-1 protein. 2. NO donors increased basal PGE(2) release although they reduced PGE(2) accumulated in the medium and cyclo-oxygenase (COX) activity when cells were stimulated with lipopolysaccharide (LPS). COX-2 protein was weakly induced by SPNO in basal conditions and in the presence of LPS a synergy for HO-1 and COX-2 protein expression was observed. 3. Our results indicate that reactive oxygen species participate in the inductive effect of NO donors or LPS on HO-1 expression, whereas endogenous NO production may play a role in the mechanism of the synergy exhibited by SPNO and LPS on HO-1 and COX-2 expression. In this system, zinc protoporphyrin IX did not affect nitrite levels but reduced COX activity. 4. The selective COX-2 inhibitors SC58125 and NS398 as well as the non-selective COX inhibitor, indomethacin, strongly reduced PGE(2) synthesis and showed a synergy with NO donors in HO-1 and COX-2 induction. Addition of PGE(2) had no effect, suggesting a mechanism independent of PGs formation. 5. In inflammatory conditions a number of factors could cooperate to induce HO-1 and COX-2, with a positive regulation by COX inhibitors.

3T3 Cells↗
PubMed2000

A comparative study of magnetic resonance cholangiography and direct cholangiography.

OBJECTIVE: Magnetic resonance cholangiopancreatography (MRCP) is a rapidly developing method for the noninvasive assessment of the biliary tree and pancreatic duct that obviates the need for contrast medium. We describe our experience with this new diagnostic imaging method in patients with obstruction of the biliary tree. We assessed both the location and cause of obstruction, and compared the results with direct cholangiography. METHODS: Between 1997 and 1998, 81 patients underwent MRCP at our facility. Two different image acquisition protocols (half-Fourier acquisition single-shot turbo spin-echo -HASTE- and rapid acquisition with relaxation enhancement -RARE-) for T2-weighted turbo spin echo sequences as well as cross-sectional fast multiplanar gradient-echo pulse (T1-weighted FL2D) and T2-weighted fast spin echo (T2 TSE) sequences were used. All patients underwent direct (either percutaneous or endoscopic retrograde) cholangiography or surgery for confirmation and/or treatment. The images obtained with MRCP were evaluated by two radiologists with expertise in biliary tree imaging who were unaware of the patient's clinical characteristics, and their diagnostic interpretations were compared with the findings obtained upon surgery or direct cholangiography. RESULTS: The sensitivity and specificity of MRCP in ruling out pathologies and detecting the presence of dilatation of the biliary tree were 100%. In assessing the level of the obstruction, sensitivity and specificity varied with location (intrahepatic/hilar, suprapancreatic, intrapancreatic or ampullary). Sensitivity in these locations was 100, 92, 69 and 86%, respectively, whereas specificity was 100, 94, 92 and 91%, respectively. In determining the cause of the obstruction, the results were variable depending on the cause: choledocholithiasis (sensitivity, 89%; specificity, 90%) malignant obstruction (sensitivity, 92%; specificity, 88%), benign stricture (sensitivity, 63%; specificity, 90%), and chronic pancreatitis (sensitivity, 50%; specificity, 99%). CONCLUSIONS: MRCP offered high diagnostic accuracy in the assessment of the occurrence and location of biliary obstruction. Sensitivity and specificity in establishing the cause varied, and were highest for choledocholithiasis and malignant obstruction. MRCP may be used instead of ERCP, which may then be reserved for patients who are likely to require surgery.

Adult↗
PubMed1999

Synthesis and pharmacological evaluation of some 8-cyanopyrido[3', 2':4,5]thieno[3,2-d]triazine derivatives as inhibitors of nitric oxide and eicosanoid biosynthesis.

A series of 8-cyanopyrido[3',2':4,5]thieno[3,2-d]-1,2,3-triazines, substituted at C-4 and C-7, were synthesized and evaluated as nitric oxide and prostaglandin E(2) inhibitors in murine peritoneal macrophages stimulated with bacterial endotoxin. Several compounds exhibited considerable activity, compounds 10 and 13 being the most interesting ones with IC(50) values of 11.2 and 3.4 microM on nitrites and 0.9 and 0.6 microM on prostaglandin E(2) production, respectively. None of the examples of pyridothienotriazines that were active at 10 microM showed any effect on inducible nitric oxide synthase, cyclooxygenase-2, and cyclooxygenase-1 enzymes, suggesting that they act by modifiying the level of expression of these inducible enzymes.

Animals↗