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Biomedical subjects

R P Carlson

Publications and source records attributed to R P Carlson.

At least 19 recordsLinked to original sources
PubMed1999

A new spin on an old model: in vivo evaluation of disease progression by magnetic resonance imaging with respect to standard inflammatory parameters and histopathology in the adjuvant arthritic rat.

OBJECTIVE: To noninvasively examine the pathogenesis of rat adjuvant-induced arthritis (AIA) by magnetic resonance imaging (MRI), and to correlate MRI indices of disease progression with classic inflammatory parameters and histologic evaluation. METHODS: AIA was established in male Lewis rats following subcutaneous injection in the right hindpaw with 0.5 mg of heat-killed Mycobacterium butyricum suspended in light mineral oil. In vivo MRI evaluations of soft tissue and bony changes in AIA rats with matched histopathology were correlated with changes in left hindpaw volumes, circulating leukocytes, acute-phase reactants, and urinary collagen crosslinks throughout the disease process. RESULTS: MRI of arthritic tibiotarsal joints of the uninjected left hindpaws from AIA rats demonstrated 2 distinct phases of disease activity. The first phase, apparent between days 10 and 18, was characterized by periarticular inflammation with marked synovitis, synovial fibroplasia, and distension of the joint capsule into the surrounding tissue. The secondary phase, occurring between days 18 and 30, was marked by continued soft tissue inflammation, periostitis with osteolysis, and periosteal new bone formation progressing to a state of near complete ankylosis by day 30. These 2 phases of disease activity observed by MRI paralleled biochemical, cellular, and histologic markers of disease progression. CONCLUSION: MRI can be used to noninvasively detect, monitor, and quantify the chronic synovitis and progressive destruction of soft tissue and bone in live AIA rats, thereby improving the ability to evaluate disease progression in this preclinical animal model of rheumatoid arthritis.

Animals↗
PubMed1998

Sirolimus (rapamycin, Rapamune) and combination therapy with cyclosporin A in the rat developing adjuvant arthritis model: correlation with blood levels and the effects of different oral formulations.

OBJECTIVE AND DESIGN: To determine whole blood levels of sirolimus, a macrolide antibiotic in the rat developing adjuvant arthritis (AA) model after dosing orally with two different vehicles, and whether combinational doses of sirolimus and cyclosporin A (CsA) produced additive or synergistic inhibitory effects in this model. MATERIAL: Male Lewis rats (150-180g). TREATMENT: Arthritis was induced by the injection (0.5 mg/ rat) of heat-killed Mycobacterium butyricum suspended in light mineral oil. Drugs were administered orally either in fine suspension (0.5% Tween 80) or in emulsion (phosal 50 PG in 1% Tween 80) at doses of 0.1 to 5 mg/kg in a 7 day, MWF or daily regimen. METHOD: Paw volumes (ml) were measured by automated mercury plethysmograph and sirolimus concentrations in whole blood were quantitated by liquid chromatography/ mass spectroscopy. RESULTS: At 72h (7 days after adjuvant) after receiving the third oral dose (4.5 mg/kg p.o.), the phosal vehicle resulted in higher sirolimus blood levels (2.5 ng/ml) than in Tween 80 (1.6 ng/ml). After the rats received the last oral dose on day 14, (7 total doses of sirolimus at 4.5 mg/kg) the sirolimus blood levels (2h after the last dose) were about 2 times higher for the phosal dosed rats (9.8 ng/ml) compared to Tween 80 dosed rats (4.6ng/ml). Even 24h after the last dose, sirolimus blood levels were still elevated in the phosal dosed rats (0.8 ng/ml) relative to 0.5% Tween 80 dosed rats (0.5 ng/ml). At day 16 in the rat developing model, sirolimus, when given in phosal vehicle, produced an ED50 of 0.28 mg/ kg (i.e. inhibition of uninjected paw edema) that was about 5.5 times lower than using 0.5% Tween 80 as the suspending agent (ED50 = 1.6mg/kg). When combining sirolimus and CsA using precalculated doses for producing an additive effect in this adjuvant model, an additive inhibitory effect on uninjected paw edema was observed at equal combinational doses of 0.5 and 2 mg/kg, respectively. CONCLUSIONS: The phosal vehicle used in administering sirolimus increases the absorption and whole blood levels in the rat and the elevated blood levels correlated positively with the therapeutic effect in the rat developing AA model. In addition, combination therapy using sirolimus and CsA produced an additive effect in rat developing AA.

Administration, Oral↗
PubMed1996

Azole phenoxy hydroxyureas as selective and orally active inhibitors of 5-lipoxygenase.

Azole phenoxy hydroxyureas are a new class of 5-lipoxygenase (5-LO) inhibitors. Structure-activity relationship studies have demonstrated that electronegative substituents on the 2-phenyl portion of the oxazole tail increased the ex vivo potency of these inhibitors. Similar substitutions on the thiazole analogs had only minor contribution to the ex vivo activity. The trifluoromethyl-substituted oxazole 24 was the best compound of the oxazole series in both the ex vivo (6 h pretreated rats) and in vivo (3 h pretreated rats) RPAR assay with ED50 values of approximately 1 and 3.6 mg/kg, respectively, but was weakly active in the allergic guinea pig assay. Oxazole 50 was equally active in both the RPAR and guinea pig in vivo models and was similar to zileuton. The unsubstituted thiazole 52 was the best compound of the thiazole series, by inhibiting the leukotriene B4 biosynthesis in the RPAR assay (3 h pretreated rats) by 99%, at an oral dose of 10 mg/kg, and the bronchoconstriction in the allergic guinea pig by 50%, at an intravenous dose of 10 mg/kg. Oxazole 24 demonstrated high and selective 5-LO inhibitory activity in the in vitro assays, with IC50 values ranging from 0.08 microM in mouse macrophages to 0.8 microM in human peripheral monocytes to 1.2 microM in human whole blood. This activity was selective for 5-LO, as concentrations up to 15 microM in mouse macrophages did not affect prostaglandin formation. Oxazole 59 was the most active inhibitor in the human monocyte assay with an IC50 value of 7 nM.

Animals↗
PubMed1995

Synthesis and antiinflammatory activity of certain 5,6,7,8-tetrahydroquinolines and related compounds.

Modification of some 8-benzylidene-5,6,7,8-tetrahydroquinolines, which have good antiulcer activity, led to three distinct classes of compounds with good in vivo antiinflammatory activity. Initial efforts led to a series of alkenes derived from 5,6,7,8-tetrahydroquinolines substituted at the 8-position. A second approach concentrated on replacing the CH linkage of these 8-benzylidene-substituted compounds with other spacer groups and increasing the size of the cycloalkyl ring from a six- to seven-membered ring, which provided 6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine analogues. Finally, the substituent was switched from the cycloalkyl ring to the 2-position of the pyridine ring. Variation of the 2-substituent was also examined. Optimal antiinflammatory activity after oral administration was found in both the rat carrageenan paw edema and rat developing adjuvant arthritis models with 2-substituted 6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridines, and of particular interest was 27 (WY-28342).

Animals↗
PubMed1995

The effects of antiinflammatory and antiallergic drugs on cytokine release after stimulation of human whole blood by lipopolysaccharide and zymosan A.

IL-1 beta, IL-8, IL-6 and TNF alpha, derived from infiltrating leukocytes, are important mediators of inflammation in arthritic and allergic diseases. Heparinized human whole blood was evaluated as a model to study the effects of various classes of antiinflammatory drugs on cytokine release/biosynthesis from leukocytes. Whole blood was stimulated with zymosan A (1.5 mg/ml) or LPS (5 micrograms/ml) for 4 h to induce cytokine release. Dexamethasone was the most potent inhibitor of TNF alpha, IL-1 beta, IL-6 and IL-8 release from LPS stimulated blood leukocytes (IC50s of 0.19, 0.11 microM, 0.16 and 0.07 respectively). In LPS stimulated blood, SKF-86002, a 5-lipoxygenase/cytooxygenasae inhibitor, and rolipram, a PDE IV inhibitor, also inhibited the release of TNF alpha (IC50s of 33 and 11 microM, respectively), IL-1 beta (IC50s of 11 and 30 microM, respectively), IL-6 (IC50s of 56 and > 30, respectively) and IL-8 (IC50s of 6.7 and 15, respectively), whereas isoproterenol (1 microM) inhibited significantly only TNF alpha release. Nonsteroidal antiinflammatory drugs, 5-lipoxygenase inhibitors and immuno-suppressive drugs were inactive at 30 microM against LPS and zymosan A stimulation of cytokine release. Using zymosan A as the stimulus, only SKF-86002 (30 microM) showed significant inhibition of IL-1 beta (-59%). This 4 h human blood assay has the potential to identify novel inhibitors and sites of actions (e.g. transcription, post-transcriptional and secretion) of new antiinflammatory drugs.

Anti-Allergic Agents↗
PubMed1995

Cellular and topical in vivo inflammatory murine models in the evaluation of inhibitors of phospholipase A2.

Several novel inhibitors of human synovial fluid phospholipase A2 (HSF-PLA2) were evaluated in cellular models of inflammatory mediator release (murine macrophage and human neutrophil) and topical in vivo inflammatory skin models in mice to ascertain the scope of effects which might be observed for PLA2 inhibitors. Potent inhibition of HSF-PLA2 in vitro can be observed with compounds such as scalaradial and ellagic acid, which both have IC50 values of 0.02 microM (using autoclaved [3H]-arachidonic-acid (AA)-labelled Escherichia coli membranes as substrate). Luffariellolide, a manoalide analog, and aristolochic acid are less potent (IC50 = 5 and 46 microM, respectively) in this assay. An interesting observation is that ellagic acid in cellular assays does not inhibit macrophage eicosanoid production and only 30% inhibition of PAF biosynthesis can be obtained at 50 microM in the human neutrophil. Possibly due to its irreversible mechanism of action, scalaradial retained its potent activity in both the macrophage (IC50 for PGE2 production = 0.05 microM) and neutrophil assays (IC50 for PAF biosynthesis = 1 microM). Aristolochic acid is active in these cellular assays (macrophage IC50 = 2.5 microM and neutrophil IC50 = 100 microM), but is consistently less active than either scalaradial or luffariellolide. The relative potencies of these compounds were determined in several murine in vivo inflammatory models such as oxazolone contact hypersensitivity, AA-induced ear edema and phorbol ester (PMA)-induced ear edema. In the mouse model of oxazolone contact hypersensitivity, these PLA2 inhibitors have little effect (< or = 30% inhibition at 400 micrograms/ear) with scalaradial and luffariellolide being less effective than either aristolochic or ellagic acid. PMA-induced ear edema was effectively inhibited by scalaradial, luffariellolide and aristolochic acid (ED50 = 70, 50 and 50 micrograms/ear, respectively) whereas ellagic acid was less effective (ED50 = 230 micrograms/ear). In AA-induced ear edema, these PLA2 inhibitors had minimal effects, as would be expected for compounds which inhibit PLA2. These results, especially those of ellagic acid, suggest that caution should be taken in the extrapolation of potency against a purified human extracellular type PLA2 to the scope of activities these compounds might have in the cellular and in vivo models. The consistency of scalaradial and luffariellolide may be inherent to their irreversible mechanism of action, which is a factor to be accounted for in the extrapolation of enzyme data to cellular and in vivo models.

Animals↗
PubMed1993

WY-50,295 tromethamine, a novel, orally active 5-lipoxygenase inhibitor: biochemical characterization and antiallergic activity.

WY-50,295 tromethamine demonstrates significant 5-lipoxygenase inhibitory activity with IC50 values ranging from 0.055 microM in rat peritoneal exudate cells, to 0.16 microM in mouse macrophages, 1.2 microM in human peripheral neutrophils and 8.1 microM in rat blood leukocytes. This activity appeared selective for 5-lipoxygenase as concentrations up to 10 microM in rat peritoneal exudate cells, and 1 microM in mouse macrophages did not effect prostaglandin generation. In non-cellular enzyme assays, WY-50,295 tromethamine displayed inhibitory activity against a soluble 5-lipoxygenase from guinea pig peritoneal exudate cells (IC50 = 5.7 microM), while it was essentially inactive against 12-lipoxygenase, 15-lipoxygenase, or prostaglandin H synthetase at concentrations up to 500 microM, or against human phospholipase A2 at concentrations up to 50 microM. In purified human blood neutrophils the inhibitory activity was reversible but did not appear dependent upon substrate concentration. IN contrast, in the guinea pig cell-free 5-lipoxygenase assay changing the arachidonic acid substrate concentration from 5 to 500 microM produced a concentration-dependent reduction in inhibitory activity. WY-50,295 tromethamine inhibited the release of peptidoleukotrienes from fragmented guinea pig lung with an IC50 of 0.63 microM. When administered p.o. with a 4 h pretreatment time, WY-50,295 tromethamine inhibited ex vivo leukotriene B4 production in rat blood leukocytes with an ED50 of 19.6 mg/kg. Against an ovalbumin-induced leukotriene dependent bronchoconstriction in anesthetized sensitized guinea pigs, WY-50,295 tromethamine inhibited the ovalbumin-induced bronchoconstriction with an i.v. ED50 of 2.5 mg/kg (5 min pretreatment) and a p.o. ED50 of 7.3 mg/kg (4 h pretreatment). Significant activity was also evident with an 18 h pretreatment. Thus WY-50,295 tromethamine is an potent and selective 5-lipoxygenase inhibitor in a number of in vitro systems. Additionally the compound is orally efficacious and has a long duration of action in an allergic bronchoconstriction model. This data suggests that WY-50,295 tromethamine may have utility in the treatment of asthma and other leukotriene-dependent pathologies.

Administration, Oral↗
PubMed1993

Pharmacological characterization of WAY-121,520: a potent anti-inflammatory indomethacin-based inhibitor of 5-lipoxygenase (5-LO)/phospholipase A2 (PLA2).

WAY-121,520 inhibited human synovial fluid PLA2 (HSF-PLA2) (IC50 = 4 microM) using arachidonic acid-labeled E. coli as substrate. Further biochemical characterization of WAY-121,520 demonstrated potent inhibition of 5-lipoxygenase (5-LO) activity in the murine macrophage (LTC4, IC50 = 4 nM) and rat PMN (LTB4, IC50 = 10 nM) and an ability to antagonize LTD4 binding to isolated guinea-pig trachea (pKB = 6.0). In vivo anti-inflammatory activity was noted in murine TPA-induced (ED50 = 91 micrograms/ear) and arachidonic acid-induced (66% inhibition at 400 micrograms/ear) ear edema and in leukotriene-dependent antigen-induced bronchoconstriction in the guinea pig (73% inhibition at 50 mg/kg, p.o.). WAY-121,520 represents a novel series of indomethacin-based inhibitors of PLA2 with anti-inflammatory activity resulting from a combination of biochemical activities (inhibition of 5-LO and PLA2 and LTD4 antagonism). This agent may provide added therapeutic efficacy over more selective inhibitors.

Animals↗
PubMed1993

Inhibition of endotoxin-induced hypothermia and serum TNF-alpha levels in CD-1 mice by various pharmacological agents.

Intraperitoneal injection of lipopolysaccharide (LPS) was used to elicit a sublethal, shock-like condition in mice. LPS, 2.5 mg/kg i.p., induced hypothermia, elevated serum TNF-alpha levels and lethality over a 48 h period in male CD-1 mice. The 5-lipoxygenase (LO) inhibitors, WY-50,295 tromethamine and zileuton (100 mg/kg p.o), significantly inhibited hypothermia at 4, 24 and 48 h after LPS. Interestingly, whereas cyclooxygenase (CO) inhibitors (ibuprofen, etodolac, naproxen and tenidap) at 40-80 mg/kg p.o. stimulated hypothermia at 4 h, they significantly reduced the later stages of hypothermia at 24-48 h. Rolipram (PDE-IV inhibitor) and dexamethasone significantly reduced hypothermia at 4-24 h and 1-24 h, respectively. All the anti-inflammatory agents significantly reduced elevated TNF-alpha levels at approximately 70 min post-LPS, except for ibuprofen. In conclusion, these anti-inflammatory standards indicate that LPS-induced shock involves multiple lipid mediators (PG's, LT's and possibly PAF) and secondary cytokine generation. This sublethal model of LPS-induced shock represents a sensitive model for estimating the efficacy of potential drug candidates for the treatment of endotoxic shock.

Animals↗
PubMed1993

The effects of anti-inflammatory and antiallergic drugs on the release of IL-1 beta and TNF-alpha in the human whole blood assay.

Heparinized human whole blood was evaluated as a model to study the effects of various classes of anti-inflammatory drugs on IL-1 beta and TNF-alpha release from leukocytes. Human whole blood was stimulated with zymosan (1.5 mg/ml) or LPS (5 micrograms/ml) to induce significant cytokine release. As previously reported, the 5-lipoxygenase/cyclooxygenase (5-LO/CO) inhibitor, SKF86002 (30 microM), significantly inhibited both IL-1 beta and TNF-alpha release using either stimulus. In contrast, the cyclooxygenase (CO) inhibitors (naproxen and ibuprofen) and the lipoxygenase (5-LO) inhibitors (zileuton, L-663536 and BWA4C) did not effect IL-1 beta or TNF-alpha release/biosynthesis. Isoproterenol (beta-agonist), rolipram (a PDE-IV inhibitor), and IBMX (a nonselective PDE inhibitor), significantly inhibited TNF-alpha but not IL-1 beta in the LPS model while having no effect in the zymosan model. This human whole blood assay is a unique and rapid method which can be used to identify novel inhibitors of IL-1 beta and TNF-alpha release/biosynthesis.

Anti-Inflammatory Agents↗