Relieving Sore Throat Formula Exerts a Therapeutic Effect on Pharyngitis through Immunoregulation and NF-κB Pathway.

Relieving Sore Throat Formula (RSTF) is a formula approved by the China Food and Drug Administration and has been used for the treatment of pharyngitis in clinic for many years. However, the potential pharmacological mechanism still remains unknown. We combined multiple methods including bioinformatics data digging, network pharmacology analysis, and pathway analysis to predict the potential target of RSTF. We verified our in silico prediction results with an in vivo/vitro antibacterial effect test, mouse phagocytic index test, proliferation, transformation, and migration of mouse spleen lymphocytes. Alteration of NF-κB pathway was determined by Western blotting, immunofluorescence, and PCR. The in vivo experiments demonstrated that the RSTF could significantly relieve the symptoms of pharyngitis. A rat saliva secretion test showed that RSTF can effectively relieve the xerostomia symptom. A phenol red excretion test showed that RSTF has an eliminating phlegm effect. A hot plate method and granuloma experiment proved that RSTF also have analgesic and anti-inflammatory effects. In silico prediction demonstrates that 70 active compounds of RSTF were filtered out through ADME screening and 84 putative targets correlated with different diseases. Pathway enrichment analysis showed that the candidate targets were mostly related to the response to bacteria and immunity signalling pathways, which are known contributors to pharyngitis. Experimental results confirmed that RSTF exerted therapeutic effects on pharyngitis mainly by antibacterial effect and downregulation of NF-κB activities. It is demonstrated both in silico and in vivo/vitro that RSTF exerted therapeutic effects on pharyngitis mainly through an antibiotic effect and downregulation of NF-κB signalling pathway.

Anti-Inflammation Effect of Small Molecule Oligopeptides Prepared from Panax ginseng C. A. Meyer in Rats.

The present study was designed to investigate the anti-inflammatory effects of ginseng oligopeptides (GOPs). For the anti-inflammatory activity, dextran-induced paw edema and granuloma models were used in Sprague-Dawley rats (180⁻200 g, 12 weeks old, n = 10). Rats were treated orally with GOPs (0, 62.5, 125, 250 and 500 mg/kg) for prophylaxis. In the granuloma model, the levels of NO, Tumor necrosis factor-α (TNF-α), interleukin IL-ß, and interleukin IL-10 in serum were evaluated. In addition, in the edema model, the level of TNF-α, prostaglandin E2 (PGE2), Leukotriene D4 (LTD4), and the platelet activating factor (RAF) in paw tissue were detected. PCR assessed the effect of GOPs on the expression of MAPK and NF-κB. The results showed that oral administration of GOPs inhibited inflammation caused by cotton pellet and dextran. GOPs significantly inhibited the edema formation via MAPK and NF-κB. These findings suggested that GOPs have a beneficial effect on acute and chronic inflammation, and the mechanism possibly mediated by inhibiting gene expression involved in inflammation and downregulating inflammatory mediators.

Physicochemical characterization of inorganic deposits associated with granulomas in cutaneous sarcoidosis.

BACKGROUND: Sarcoidosis, characterized by epithelioid granulomas, is considered to be caused by a complex interplay between genetics and environmental agents. It has been hypothesized that exogenous inorganic particles as crystalline silica could be a causal or adjuvant agent in sarcoidosis onset. OBJECTIVES: To investigate the location, frequency and physicochemical characteristics of foreign materials and mineral tissue deposits in the granulomatous area of cutaneous sarcoidosis. METHODS: Skin biopsies (n = 14) from patients diagnosed with cutaneous sarcoidosis (mean age 43 years; 11 patients with extracutaneous involvement) were investigated using polarized light examination (PLE), µFourier Transform Infra-Red (µFT-IR) spectroscopy and Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (FE-SEM/EDX). RESULTS: Combined PLE, µFT-IR, FE-SEM/EDX analysis allowed to characterize mineral deposits in 7/14 biopsies (50%). It identified crystalline silica (SiO2 ) inside granulomas in three biopsies and calcite (CaCO3 ) at their periphery in 4. CONCLUSION: This study emphasizes the need of using combined methods for assessment of mineral deposits in granulomatous diseases. According to the location and characteristics of deposits, we can hypothesize that SiO2 particles contribute to the granuloma formation, whereas CaCO3 deposits are related to the granuloma biology. However, the significance of the association between SiO2 deposits and sarcoidosis is still disputed.

Evaluation of the anti-inflammatory effect of an anti-platelet agent crinumin on carrageenan-induced paw oedema and granuloma tissue formation in rats.

The present study was designed to explore the anti-inflammatory activity of an anti-platelet agent crinumin, by various in vitro and in vivo inflammation models. Firstly, crinumin protein was purified through cation exchange chromatography; then, in vitro activity was estimated by albumin denaturation assay and HRBC membrane stabilization assay. Carrageenan-induced paw oedema and cotton pellet-induced granuloma models were used for in vivo anti-inflammatory activity assessment in rats. In both models, rats were pre-treated for 7 days with crinumin (25-50 µg/ml) and diclofenac sodium (50 µg/ml). Expression of P-selectin (in serum and plasma) through ELISA and NF-κB (in paw and granulomatous tissues) through western blotting was checked. Our results showed that crinumin at both doses (25 or 50 µg/kg of b.w.) significantly (p < 0.05) reduced the paw oedema formation in a dose-dependent manner in the second phase of inflammation and significant (p < 0.05) reduction of wet and dry weight of granuloma was observed indicating the anti-inflammatory potential of crinumin. Crinumin decreased the expression of P-selectin and NF-κB indicating its potential role in decreasing platelet activation and healing inflammation. Histopathological studies additionally proved the efficacy of drug in treating inflammation. The results of the study suggest that the crinumin might have an inhibitory role in atherosclerosis as platelet aggregation and inflammation are the key processes involved in atherosclerotic disorders.

Impact of vitamin E-blended UHMWPE wear particles on the osseous microenvironment in polyethylene particle-induced osteolysis.

Aseptic loosening mediated by wear particle-induced osteolysis (PIO) remains the major cause of implant loosening in endoprosthetic surgery. The development of new vitamin E (α-tocopherol)-blended ultra-high molecular weight polyethylene (VE-UHMWPE) with increased oxidation resistance and improved mechanical properties has raised hopes. Furthermore, regenerative approaches may be opened, as vitamin E supplementation has shown neuroprotective characteristics mediated via calcitonin gene-related peptide (CGRP), which is known to affect bone remodeling in PIO. Therefore, the present study aimed to further clarify the impact of VE-UHMWPE wear particles on the osseous microenvironment and to identify the potential modulatory pathways involved. Using an established murine calvaria model, mice were subjected to sham operation (SHAM group), or treated with UHMWPE or VE-UHMWPE particles for different experimental durations (7, 14 and 28 days; n=6/group). Morphometric analysis by micro-computed tomography detected significant (p<0.01) and comparable signs of PIO in all particle-treated groups, whereas markers of inflammation [tumor necrosis factor (TNF)-α/tartrate resistant acid phosphatase (TRAP) staining] and bone remodeling [Dickkopf-related protein 1 (DKK-1)/osteoprotegerin (OPG)] were most affected in the early stages following surgery. Taking the present data into account, VE-UHMWPE appears to have a promising biocompatibility and increased ageing resistance. According to the α-CGRP serum levels and immunohistochemistry, the impact of vitamin E on neuropeptidergic signaling and its chance for regenerative approaches requires further investigation.

Localized chrysiasis, aluminum salt deposition and dystrophic calcification a decade after gold injections.

Localized chrysiasis is rare and can occur in two settings: after localized or traumatic implantation of elemental gold or gold salts or after localized laser or light therapy in someone who has been previously exposed to systemic gold therapy. We report a unique case of localized chrysiasis with associated aluminum salt deposition and sclerosing lipogranulomas because of previous injections of aurothioglucose (Solganal®). The unique histopathologic findings seen in this case have not been previously reported.

Potential anti-inflammatory effect of Leea macrophylla Roxb. leaves: a wild edible plant.

Leea macrophylla (Leeaceae) is a wild edible plant with ethomedicinal importance as anti-inflammatory agent. However, no systematic studies on its anti-inflammatory activity and mechanisms have been reported. Present study was undertaken to evaluate anti-inflammatory activity of methanol extract of L. macrophylla leaves. Phytochemical investigation revealed presence of sterols, triterpenoids and ascorbic acid in extract. Methanol extract inhibited lipopolysaccharide stimulated production of inflammatory mediators viz. prostaglandin E2, tumor necrotic factor-α, interleukin-6 and interleukin-1ß in vitro in mouse peritoneal macrophages. Additionally, the in vivo anti-inflammatory activity of this extract was evaluated by using carrageenan induced paw edema and cotton pellet granuloma assays in experimental rats. Oral administration of extract (100 and 200 mg/kg) exhibited dose dependant inhibition of carrageenan induced inflammation (p<0.05) and the reduction of the granuloma tissue formation (p<0.05-0.01). The extract (100 and 200 mg/kg, orally) exhibited significant central and peripheral analgesic activity in hot-plate test (p<0.01) and acetic acid induced writhing test (p<0.05-0.01) respectively in experimental mice. Treatment with extract (100 and 200 mg/kg, orally) significantly reduced the yeast provoked elevated body temperature (p<0.05-0.01) in experimental rats. These results confirmed the traditional anti-inflammatory indication of L. macrophylla leaves.

Double Y-stenting for tracheobronchial stenosis.

The purpose of the present study was to evaluate the feasibility, efficacy and safety of the double Y-stenting technique, by which silicone Y-stents are placed on both the main carina and another peripheral carina, for patients with tracheobronchial stenosis. Under general anaesthesia, using rigid and flexible bronchoscopes, a Dumon™ Y-stent (Novatech, La Ciotat, France) was first placed on the primary right or secondary left carina followed by another Y-stent on the main carina so as to insert the bronchial limb of the stent into the first Y-stent. Patients who underwent double Y-stent placement during 3 yrs and 1 month in a single centre were retrospectively reviewed. In the study period, 93 patients underwent silicone stent placement and 12 (13%) underwent double Y-stent placement (11 for right and one for left bronchus). A combination of Y-stents, 14 × 10 × 10 mm and 16 × 13 × 13 mm in outer diameter, were most frequently used. Dyspnoea was relieved in all patients. Six out of seven patients with supplemental oxygen before stent placement could be discharged without supplemental oxygen. Median survival after stenting was 94.5 days. One pneumothorax and one granuloma formation occurred. Double Y-stent placement for patients with tracheobronchial stenosis was technically feasible, effective and acceptably safe.

Xanthohumol-supplemented beer modulates angiogenesis and inflammation in a skin wound healing model. Involvement of local adipocytes.

Angiogenesis and inflammation are two intermingled processes that play a role in wound healing. Nevertheless, whenever exacerbated, these processes result in nonhealing wounds. Xanthohumol (XN), a beer-derived polyphenol, inhibits these processes in many physiopathological situations. This study aimed at examining whether XN ingestion affects wound healing. Wistar rats drinking water, 5% ethanol, stout beer (SB) or stout beer supplemented with 10 mg/L XN (Suppl SB) for 4 weeks, were subjected to a 1.5 cm full skin-thickness longitudinal incision, and further maintained under the same beverage conditions for another week. No differences in beverage consumption or body weight were found throughout the study but food intake decreased in every group relative to controls. Consumption of Suppl SB resulted in decreased serum VEGF levels (18.42%), N-acetylglucosaminidase activity (27.77%), IL1ß concentration (9.07%), and NO released (77.06%), accompanied by a reduced redox state as observed by increased GSH/GSSG ratio (to 198.80%). Also, the number of blood vessels within the wound granulation tissue seems to reduce in animals drinking Suppl SB (23.08%). Interestingly, SB and primarily Suppl SB showed a tendency to increase adipocyte number (to 194.26% and 156.68%, respectively) and reduce adipocyte size (4.60% and 24.64%, respectively) within the granuloma. Liver function and metabolism did not change among the animal groups as analyzed by plasma biochemical parameters, indicating no beverage toxicity. This study shows that XN intake in its natural beer context reduced inflammation, oxidative stress, and angiogenesis, ameliorating the wound healing process, suggesting that this polyphenol may exert beneficial effect as a nutritional supplement.

Anti-inflammatory and analgesic activity of protocatechuic acid in rats and mice.

Anti-inflammatory and analgesic activity of protocatechuic acid (PCA), a natural product, was evaluated in different rat models (viz., carrageenan-induced paw oedema, cotton pellet-induced granuloma and Freund's adjuvant arthritis) of inflammation and chemical and heat induced mouse models of pain. Treatment with PCA inhibited significantly different biological parameters like hind paw oedema, granuloma exudates formation and arthritis index in carrageenan oedema, cotton pellet granuloma and Freund's adjuvant arthritis, respectively. The biochemical changes viz., glutathione, superoxide dismutase, catalase, lipid peroxidation and NO in oedematous or in liver tissues and serum alanine aminotransferase and lactic dehydrogenase occurred during different types of inflammation were either significantly restored or inhibited with PCA pretreatment. Present experimental findings demonstrate promising anti-inflammatory and analgesic activity of PCA which is comparable with that of standard drugs used.

CD8-positive granulomatous mycosis fungoides: a case report with review of the literature.

Granulomatous mycosis fungoides (GMF) represents an uncommon variant of mycosis fungoides (MF) characterized by the presence of an associated granulomatous reaction. Most cases of GMF are CD4 positive, and CD8 positive cases are extremely rare. Herein, we report a case of CD8-positive GMF. A 75-year-old Japanese woman presented with brownish maculae on the trunk and upper and lower extremities. She had been diagnosed with MF, and most of the eruption improved by psoralen ultraviolet A therapy. However, the eruption relapsed and gradually expanded 5 months prior to her visit to our hospital. Histopathology showed an atypical lymphocytic infiltrate in the dermis accompanied by granulomatous reaction with multinucleated giant cells. Epidermotropism was evident and elastophagocytosis was also found. Immunohistochemically, the atypical lymphocytes expressed betaF1, CD3 and CD8, and some of the atypical lymphocytes were also T cell intracellular antigen-1 positive. These findings were consistent with CD8-positive GMF. The dermatopathological diagnosis of GMF is challenging in some cases because of the prominent secondary granulomatous reaction. Therefore, when dermatopathologists diagnose granulomatous skin lesions, GMF should also be considered. In addition, the prognosis of GMF, especially CD8-positive GMF, is still controversial. Additional studies are required to clarify the clinicopathological features of CD8-positive GMF.

SP-D counteracts GM-CSF-mediated increase of granuloma formation by alveolar macrophages in lysinuric protein intolerance.

BACKGROUND: Pulmonary alveolar proteinosis (PAP) is a syndrome with multiple etiologies and is often deadly in lysinuric protein intolerance (LPI). At present, PAP is treated by whole lung lavage or with granulocyte/monocyte colony stimulating factor (GM-CSF); however, the effectiveness of GM-CSF in treating LPI associated PAP is uncertain. We hypothesized that GM-CSF and surfactant protein D (SP-D) would enhance the clearance of proteins and dying cells that are typically present in the airways of PAP lungs. METHODS: Cells and cell-free supernatant of therapeutic bronchoalveolar lavage fluid (BALF) of a two-year-old patient with LPI were isolated on multiple occasions. Diagnostic BALF samples from an age-matched patient with bronchitis or adult PAP patients were used as controls. SP-D and total protein content of the supernatants were determined by BCA assays and Western blots, respectively. Cholesterol content was determined by a calorimetic assay or Oil Red O staining of cytospin preparations. The cells and surfactant lipids were also analyzed by transmission electron microscopy. Uptake of Alexa-647 conjugated BSA and DiI-labelled apoptotic Jurkat T-cells by BAL cells were studied separately in the presence or absence of SP-D (1 microg/ml) and/or GM-CSF (10 ng/ml), ex vivo. Specimens were analyzed by light and fluorescence microscopy. RESULTS: Here we show that large amounts of cholesterol, and large numbers of cholesterol crystals, dying cells, and lipid-laden foamy alveolar macrophages were present in the airways of the LPI patient. Although SP-D is present, its bioavailability is low in the airways. SP-D was partially degraded and entrapped in the unusual surfactant lipid tubules with circular lattice, in vivo. We also show that supplementing SP-D and GM-CSF increases the uptake of protein and dying cells by healthy LPI alveolar macrophages, ex vivo. Serendipitously, we found that these cells spontaneously generated granulomas, ex vivo, and GM-CSF treatment drastically increased the number of granulomas whereas SP-D treatment counteracted the adverse effect of GM-CSF. CONCLUSIONS: We propose that increased GM-CSF and decreased bioavailability of SP-D may promote granuloma formation in LPI, and GM-CSF may not be suitable for treating PAP in LPI. To improve the lung condition of LPI patients with PAP, it would be useful to explore alternative therapies for increasing dead cell clearance while decreasing cholesterol content in the airways.

Further pharmacological studies on aqueous seed extract of Aframomum melegueta in rats.

This present study investigates the effect of an aqueous seed extract of Aframomum melegueta, on leukocytes migration and on phenylhydrazine-treated rat red blood cells (RBC). The effect of Aframomum melegueta on the number of white blood cells (WBC), in inflammatory exudates, was assessed by utilizing the granuloma air pouch model, for chronic inflammation in carrageenin-treated rats. The extract was tested for its anti-oxidant and membrane-stabilizing effects, in rat RBC exposed to phenylhydrazine. Aframomum melegueta was found to significantly reduce the number of WBC, in the fluid in a dose-related manner. The extract also produced significant inhibition of rat red blood cells lysis exposed to phenylhydrazine, which suggests a membrane-stabilizing effect. It further demonstrated a potent anti-oxidant activity, as it significantly reduced the levels of malonydialdehyde (MDA) formation in rat RBC exposed to phenylhydrazine. The results of this study, suggest that Aframomum melegueta possess membrane-stabilizing activity, along with anti-oxidant property and may also have a modifying effect, on the responses of WBC to tissue injury.

PD-L1 (B7-H1) expression by urothelial carcinoma of the bladder and BCG-induced granulomata: associations with localized stage progression.

BACKGROUND: PD-L1 (programmed death ligand 1, B7-H1) is a cell surface glycoprotein that can impair T-cell function. PD-L1 is aberrantly expressed by multiple human malignancies and has been shown to carry a highly unfavorable prognosis in patients with kidney cancer. The role of PD-L1 was evaluated as a mechanism for local stage progression in urothelial carcinoma (UC) of the bladder. METHODS: Using immunohistochemistry, PD-L1 expression was evaluated in a cohort of 280 high-risk UCs of the bladder. PD-L1 was modeled as a predictor of bladder cancer stage using ordinal logistic regression. Other covariates evaluated as potential confounders included age, gender, tumor grade, and lymphocytic infiltration. Further, PD-L1 was evaluated as a potential mechanism of bacillus Calmette-Guerin (BCG) failure in the subset of high-risk nonmuscle-invasive tumors that received this treatment. RESULTS: PD-L1 expression was observed in 7% of pTa, 16% of pT1, 23% of pT2, 30% of pT3/4, and 45% of carcinoma in situ (CIS) tumors. PD-L1 expression was associated with high-grade tumors (odds ratio [OR] = 2.4, P = .009) and tumor infiltration by mononuclear cells (OR = 5.5, P = .004). We observed that the key determinants of stage progression in this cohort were World Health Organization/International Society of Urologic Pathology (WHO/ISUP) high-grade tumor pathology (OR = 4.77, 95% confidence interval [CI]: 2.73-8.34; P < .001) and PD-L1 expression (OR = 2.20, P = .012). PD-L1 expression was found to be extremely abundant in the BCG-induced bladder granulomata in 11 of 12 patients failing BCG treatment. CONCLUSIONS: Collectively, these data indicate that tumor PD-L1 may facilitate localized stage-advancement of UC and attenuate responses to BCG immunotherapy by neutralizing T cells that normally guard against cancer invasion from the epithelium into the bladder musculature.

Altered host:pathogen interactions conferred by the Blau syndrome mutation of NOD2.

Blau syndrome (BS) is a rare familial granulomatous disease manifested by uveitis, arthritis and skin rash. BS has recently been found to be associated with a distinctive mutation in NOD2, which encodes an intracellular toll-like receptor. We have compared host cell interaction with bacterial challenge in U937 cells expressing wild type human NOD2 (NOD2(wt)), mutant NOD2 (NOD2(Blau)), or a vector control (VC). The cells were incubated with Salmonella typhimurium. Intracellular uptake was assessed by harvesting the cells at different time points following invasion and quantitating the CFU, recovered after gentamicin treatment to kill extracellular organisms. Expression of TNF-alpha, TLR2 and TLR4 was determined by semi-quantitative RT-PCR under resting conditions and after stimulation by bacteria. Invasion of target cells with S. typhimurium was diminished in the presence of NOD2(Blau). Expression of TNF-alpha mRNA was enhanced following bacterial invasion in all cell lines but NOD2(Blau) was associated with a more rapid decline in TNF-alpha expression. Kinetics of intracellular clearance of bacteria indicated a relative defect in NOD2(Blau) compared to controls. This clearance defect may be related to the lack of sustained TNF-alpha seen in the early stages. These events were not related to differential TLR2 or TLR4 expression since there were no significant differences seen between the cell lines after bacterial stimulation. Our findings indicate that the NOD2 mutation associated with this syndrome alters host:microbial interaction, and this may have relevance to triggering factors in the ocular and joint inflammation seen in BS.

The cytosolic pattern-recognition receptor Nod2 and inflammatory granulomatous disorders.

Pattern-recognition receptors are a first line of defense against invading pathogens. Recent advances in the understanding of innate immunity have revealed a novel family of cytosolic pattern-recognition receptors called Nods, which contain an amino-terminal effector-binding domain, a centrally located nucleotide-binding oligomerization domain (NOD) and a carboxy-terminal ligand recognition domain. Hereditary mutations of Nods have been reported in patients with certain inflammatory diseases; for example, Nod2 mutations are associated with the inflammatory granulomatous disorders, Crohn's disease and Blau syndrome. Missense mutations of Nod2 are also associated with early-onset sarcoidosis, a rare but sporadic disease. Because Nod2 is predominantly expressed in monocytes and recognizes a component of bacterial peptidoglycan, analysis of its function may help in understanding the role of the immune system in granuloma formation.

Efficacy of dalbavancin against methicillin-resistant Staphylococcus aureus in the rat granuloma pouch infection model.

Infections due to methicillin-resistant Staphylococcus aureus (MRSA) are an important cause of morbidity and mortality in hospital patients. Moreover, increased incidences of outpatient MRSA have been recently reported. This study investigated the bactericidal activity of dalbavancin, a novel, semisynthetic glycopeptide antibiotic, against methicillin-sensitive S. aureus (MSSA) and MRSA in the rat granuloma pouch infection model. A single intravenous dose of 10 mg of dalbavancin/kg of body weight reduced the viable MRSA count in pouch exudates by more than 2 log CFU/ml, and regrowth was prevented for up to 120 h. Comparable results with vancomycin required four 100-mg/kg intramuscular doses. With one or two doses of vancomycin, the bacterial load declined over proportionately shorter periods of time, followed by regrowth. Reduction of the bacterial load obtained with 100- and 200-mg/kg oral doses of linezolid was relatively transient, with regrowth starting at 48 h. A single 10-mg/kg dose of dalbavancin reduced the MSSA count at 24 h to below the limit of detection, with no regrowth for at least 96 h. Dalbavancin demonstrated good exudate penetration; the ratio of the area under the curve (AUC) in plasma to the AUC in pouch exudate was 1.01. The in vivo activity of dalbavancin in this model is consistent with the antibiotic concentrations that are reached and maintained for extended periods of time after a single 10-mg/kg dose and with in vitro data showing that these concentrations are bactericidal for staphylococci. The pharmacokinetic and efficacy data seen in this relevant model of infection suggest that dalbavancin may be administered less frequently than vancomycin and linezolid.

Modulation of nitric oxide synthesis in inflammation. Relationship to oxygen-derived free radicals and prostaglandin synthesis.

The role of nitric oxide (NO) derived from constitutive (cNOS) and inducible (iNOS) nitric oxide synthases and its relationship to oxygen-derived free radicals and prostaglandins was investigated in two models of inflammation, namely, carrageenan granuloma air pouch (acute model) and Freund's adjuvant-induced arthritis (chronic model) in rats. Inflammation was assessed by measurement of NO and prostaglandin E2 (PGE2) levels and the lysosomal leakage of the enzyme N-acetyl-B-D-glucosaminidase (NAG) into the exudate of the granuloma pouch 4 h after carrageenan injection. Evaluation of paw volume and determination of serum NO, lipid peroxide (LP), and PGE2 levels were used for the assessment of adjuvant-induced arthritis after either 4 days (early phase) or 16 days (late phase) of adjuvant injection. Results of the study showed that the administration of either NG-nitro-L-arginine methyl ester (L-NAME, non-selective cNOS/iNOS inhibitor) or aminoguanidine (AG, selective iNOS inhibitor), prior to carrageenan injection or during development of adjuvant arthritis, caused a significant reduction in NO and PGE2 levels and in the NAG activity of the granuloma inflammatory exudate, whereas decreases in paw volume and in serum NO level were noticed in the adjuvant model as related to untreated rats. Similar treatment with L-arginine failed to elaborate a significant change in the parameters measured. Other observations included: no noticeable differences between the results of early and late phases of adjuvant arthritis; no clear correlation between NO, LP and PGE2 levels in the adjuvant arthritis inflammation and inability of the NOS inhibitors to modify the levels of serum LP that is increased during adjuvant-induced arthritis. The data give further evidence that NO is implicated in the development of both acute and chronic inflammation and that NOS inhibitors have potential antiinflammatory activity. Further studies are required to unravel the mechanisms by which NO interacts with other mediators of inflammation.