Anti-resorptive therapy and MRONJ. A survey of the Italian Society of Periodontology and Implantology.

OBJECTIVES: Anti-resorptive agents have been linked to the development of MRONJ in patients undergoing dental surgical procedures. This survey aims to explore the level of knowledge and experience of Italian Society of Periodontology and Implantology members in the management of patients treated with anti-resorptive agents and with the risk of developing MRONJ. MATERIALS AND METHODS: An 18-item questionnaire was submitted by e-mail to the SIdP members. Statistical analyses were carried out. Continuous variables were described as mean ± standard deviation (SD) or median, and first and third quartile according to distribution's normality. Normality of data was checked with Shapiro-Wilk test. RESULTS: Four hundred and fifty-one questionnaires were returned by e-mail (32%). Most of the respondents were private practitioners (81.8%). Only 47.7% declared to be highly confident in managing patients on anti-resorptive therapy while 92.5% reported to have performed tooth extractions and 52.3% implant surgery in patients under anti-resorptive therapy for osteometabolic disorders. One or more MRONJ-affected patients were encountered by 63.2% of the respondents. CONCLUSIONS: This survey highlights the need to develop a "dedicated" program both for dentists and prescribers to improve the level of cooperation and to increase the level of awareness of patients treated with anti-resorptive agents.

Gender-related differential effect of tachykinin NK2 receptor-mediated visceral hyperalgesia in guinea pig colon.

BACKGROUND AND PURPOSE: The tachykinin NK2 receptor antagonist ibodutant is under Phase III clinical investigation to treat female patients with irritable bowel syndrome. The aim of this study was to investigate the NK2 receptor-related gender specificity in a model of colitis. EXPERIMENTAL APPROACH: Colitis was induced by rectal instillation of 2,4,6-trinitrobenzenesulfonic acid (TNBS, 0.5 mL, 30 mg·mL(-1) in 30% ethanol) in female and male guinea pigs. Electromyographic recording of the responses to colorectal distension (CRD) was made 3 days later. Ibodutant (0.33 , 0.65, 1.9 and 6.5 mg·kg(-1) ) was given s.c., 30 min before CRD. Release of neurokinin A and substance P from isolated mucosal and smooth muscle tissues following treatment with KCl (80 mM) or capsaicin (10 µM) was measured by EIA. Plasma pharmacokinetics of ibodutant following a single s.c. administration (0.73 or 2.1 mg·kg(-1) ) were measured over 24 h. KEY RESULTS: Ibodutant did not affect abdominal contractions in control animals. After TNBS-induced colitis, ibodutant prevented the increased visceral hypersensitivity to CRD in females, at lower doses than in males. Ibodutant pharmacokinetics did not differ between females and males. Tachykinins release was greater in smooth muscle than in mucosal samples. Capsaicin-stimulated release of tachykinins from inflamed mucosal samples from females was significantly lower than in males. CONCLUSIONS AND IMPLICATIONS: Ibodutant prevented abdominal nociception in a model of visceral hypersensitivity in guinea pigs with a greater efficacy in females than in males. Our results highlight a gender-related difference in colonic visceral hypersensitivity and mucosal nerve activation.

Root caries: a periodontal perspective.

BACKGROUND AND OBJECTIVE: A prevailing dental problem in the periodontal patient is root caries. Specifically, periodontal involvement often results in root surfaces becoming exposed and at risk for this condition. Periodontal therapy often leads to increased gingival recession as well, and the associated increased root caries risk may compromise the long-term success and survival of periodontally treated teeth.This narrative review will address the topic of root caries in the periodontal patient, focusing on unmet research needs. MATERIAL AND METHODS: The Medline database was searched to identify items dealing with root caries, in terms of clinical features, diagnosis, pathogenic mechanisms and histopathology, as well as epidemiology, focusing then on the relationship between root caries and periodontal disorders. RESULTS: Although there is extensive literature on root caries, consensus is lacking regarding certain aspects, such as diagnostic criteria, prevalence within populations and indisputable risk factors. Advancing age could be an aggravating factor in susceptibility to root caries for the periodontal patient; however, definitive evidence in this regard is still missing. Similarly, full awareness of the increased risk of root caries in patients with periodontal disease or long-term periodontal treatment appears to be still lacking. CONCLUSION: Research regarding root caries in age-specific (elderly) periodontal patients is needed. Improved oral hygiene practices, locally applied preventive measures, good dietary habits and regular dental check-ups are crucial approaches to prevent both periodontal disease progression and root caries. Periodontal patients with root exposure should follow a strict root caries prevention protocol, as an integral component of their periodontal maintenance therapy.

Antitumour effect of combination treatment with Sabarubicin (MEN 10755) and cis-platin (DDP) in human lung tumour xenograft.

PURPOSE: Sabarubicin (MEN 10755), a new disaccaride anthracycline, has shown greater efficacy than Doxorubicin in a large panel of preclinical models and now it is in phase II clinical trials. Its promising antitumour activity promoted considerable interest to combine Sabarubicin with other antitumour agents. Thus, the purpose of this study was to evaluate in vitro cytotoxic effects and in vivo antitumour activities produced by the combination of Sabarubicin and cisplatin (DDP). METHODS: The antitumour effect of Sabarubicin and DDP association was investigated, in vitro and in vivo, in preclinical models of lung cancer i.e.: the non-small cell lung carcinoma (NSCLC) H460 and the small-cell lung carcinoma (SCLC) GLC4 in terms of synergism, additivity or antagonism in order to establish the best schedule for the combined treatment. Further, the correlation between antitumour activity and the pharmacokinetic parameters of the studied combination was also evaluated. RESULTS: The drug combination in vitro was in general more cytotoxic than the single drug alone, indicating the presence of a synergistic effect in both tumour cell lines. Also, in the xenograft experiments a superior antitumoral effect was observed when Sabarubicin was combined with DDP. The antitumour efficacy of Sabarubicin (6 mg/kg q4d x 5) combined with DDP (6 mg/kg q4d x 3) greatly depended on the schedule of administration. In H460 tumour line, the sequential combination was more effective than the simultaneous administration of the two agents, although the antitumour efficacy was not dependent on the sequence of combination. On the other hand, a strong sequence-dependent effect was observed when Sabarubicin was combined with DDP in SCLC, GLC4. In particular, the highest value of LCK = 6.7 was obtained when administration of DDP followed by 24 h that of Sabarubicin. Pharmacokinetics of Sabarubicin in combination with DDP was evaluated at 6 mg/kg for both drugs with different sequential schedule. The experimental data showed no evidence for pharmacokinetics drug-drug interaction. CONCLUSION: These preclinical results indicate the potential for a strong antitumour activity in lung tumours of the combination Sabarubicin and DDP. In particular, in SCLC the best response should be given by a sequence with administration of Sabarubicin followed 24 h later by that of DDP. Clinical trials based on these results are ongoing.

Heterogeneous effect of leucotriene CysLT1 receptor antagonists on antigen-induced motor and inflammatory responses in guinea-pig airways.

1. The effect of montelukast or MEN91507, selective leucotriene CysLT1 receptor antagonists, on antigen-induced airway inflammation and bronchoconstriction were compared in anaesthetized guinea-pigs. 2. In sensitized animals, ovalbumin (0.3 mg kg(-1), i.v.)-induced microvascular leakage in trachea, intrapulmonary airways, total lung (parenchyma and intrapulmonary airways) and urinary bladder was reduced by MEN91507 (0.01-1 micromol kg(-1), i.v.), whereas montelukast (0.01-1 micromol kg(-1), i.v.) antagonized the effect of the antigen only in the lung and urinary bladder. 3. Ovalbumin (1 mg kg(-1), i.v.)-induced bronchoconstriction was dose dependently antagonized by MEN91507 (10-30 micromol kg(-1), i.v.), whereas the effect of montelukast (0.1-30 micromol kg(-1), i.v.) was marginal (15-30% inhibition). Neither MEN91507 nor montelukast (30 micromol kg(-1), i.v.) affected the bronchoconstrictor response induced by acetylcholine (0.3 micromol kg(-1), i.v.) in sensitized animals. 4. It is concluded that montelukast and MEN91507 display a differential activity against the effect of endogenous leucotrienes, despite the fact that both compounds show a similar antagonist profile against exogenous leucotrienes acting through CysLT1 receptors.

Clinical pharmacokinetics of parenteral dexketoprofen trometamol in healthy subjects.

Dexketoprofen trometamol, a highly water-soluble salt of the active enantiomer of rac-ketoprofen, is a nonsteroidal antiinflammatory drug used for pain relief. Two studies were conducted to determine the pharmacokinetics of the drug in healthy subjects following single intravenous (i.v.) and intramuscular (i.m.) doses of dexketoprofen. In the first study, 6 male and 6 female volunteers received 50 mg dexketoprofen (74 mg dexketoprofen trometamol) by i.v. bolus. In the second one, another 6 male and 6 female subjects received 25 mg and 50 mg of dexketoprofen by the i.m. route. Dexketoprofen plasma concentrations were determined by reverse-phase high-performance liquid chromatography (HPLC). No serious adverse events were observed and all volunteers completed the study. The main pharmacokinetic parameters were determined by a noncompartmental approach. Following the i.v. bolus, mean (+/- SEM) area under the curve AUC0-x and clearance (CL) were 9005 +/- 422 ng.h/ml and 0.089 +/- 0.004 l/h/kg. Volumes of distribution Vi and Vss averaged 0.060 +/- 0.006 l/kg and 0.104 +/- 0.003 l/kg. Mean elimination half-life (t1/2e) and MRT were 1.05 +/- 0.04 h and 1.18 +/- 0.05 h. Following single i.m. 25 mg and 50 mg dexketoprofen, a rapid absorption was observed, with tmax values ranging from 0.17 h to 0.75 h. The corresponding Cmax averaged 1851 +/- 182 ng/ml and 3813 +/- 169 ng/ml, and mean AUC0-x were 3033 +/- 193 ng.h/ml and 5878 +/- 228 ng.h/ml, respectively. No significant differences by gender were obtained following both parenteral routes. A dose proportionality in Cmax and AUC0-x was observed. Dexketoprofen pharmacokinetics following i.v. and i.m. routes, together with the availability of a single 2 ml formulation, allows for a potential advantageous rapid switch to the oral formulation when clinically possible.

Single and repeated dose pharmacokinetics of dexketoprofen trometamol in young and elderly subjects.

Dexketoprofen trometamol, a high water-soluble salt of the active enantiomer of rac-ketoprofen, is a nonsteroidal antiinflammatory drug (NSAID) widely used for pain relief. This study was conducted to determine the pharmacokinetics of this analgesic agent in elderly subjects and to compare them with young volunteers following single and repeated oral doses. Twelve healthy young and 12 elderly subjects received 25 mg oral dexketo- profen (equivalent to 37 mg of its tromethamine salt) as a single dose (day 1) and 3-day repeated doses (1 dose every 8 h for a total of 10 doses). Serial concentrations of dexketoprofen were determined in plasma and urine by a reverse-phase HPLC/ultraviolet procedure over 24 h on day 1 and after the last 10th repeated t.i.d. dose. Compared to young subjects, elderly subjects showed significant increases in AUC and t1/2,z and decreases in CL/F following single and repeated doses. After single dosing, the corresponding mean +/- SD values were 5106.6 +/- 1873.0 vs. 3605.4 +/- 897.9 ng.h/ml (p = 0.015); 1.59 +/- 0.40 vs. 1.12 +/- 0.20 h (p < 0.001); and 1.11 +/- 0.29 vs. 1.63 +/- 0.36 ml/min/kg (p < 0.001). After the repeated dose, AUC, t1/2,z and CL/F averaged 5067.8 +/- 1373.4 vs. 3194.4 +/- 694.3 ng.h/ml (p < 0.001); 1.65 +/- 0.44 vs. 1.11 +/- 0.29 h (p < 0.005); and 1.12 +/- 0.23 vs. 1.87 +/- 0.42 ml/min/kg (p < 0.001). Median tmax was 0.5 h. Cumulative excretions in urine up to 24 h of unbound, conjugated and total dexketoprofen were similar among the groups. These results suggest that dexketoprofen elimination is reduced in the elderly. Although no drug accumulation in plasma was observed after single and repeated dosing, the renal function decline in elderly patients calls for a cautious dose-adjustment in this population.

Pharmacokinetics of dexketoprofen trometamol in subjects with mild and moderate chronic renal insufficiency.

The influence of mild to moderate chronic renal insufficiency on the pharmacokinetics of dexketoprofen trometamol was evaluated. Dexketoprofen was administered to volunteers with mild (n = 8) or moderate (n = 8) renal impairment and to healthy subjects (n = 8), as a single 12.5 mg oral dose (equivalent to 18.5 mg of the tromethamine salt). All subjects completed the study and no serious adverse events were recorded. Mild and moderate renal insufficiency increased Cmax by approximately 22% and 37%, respectively, as related to normal subjects (p < 0.05 for moderate renal dysfunction). No statistically significant differences between groups were obtained for tmax, AUC, CL/F, renal CL and V/F. The cumulative urinary excretion of unchanged dexketoprofen, assessed up to 24 hours postdose, was similar in all groups (median values of 7.0%, 8.1% and 9.7% of the administered dose). On the contrary, cumulative urinary excretions of conjugated dexketoprofen decreased in subjects with mild or moderate renal insufficiency when compared to healthy controls (median and 95% CI for differences: -3.3% (-14.8% to 2.6%) and -7.3% (-22.2% to -0.2%), respectively). Conservatively, a dose adjustment of dexketoprofen in patients with impaired renal function is recommended.

Single and repeated dose pharmacokinetics of dexketoprofen trometamol in patients with impaired liver function.

Dexketoprofen trometamol, a high water-soluble salt of the active enantiomer of rac-ketoprofen, is a nonsteroidal antiinflammatory drug (NSAID) used for pain relief. This study compared the pharmacokinetics of dexketoprofen in patients with impaired liver function and normal subjects following single and repeated oral dosing. Subjects with normal liver function (n = 6) and with Child-Pugh A (n = 7) or Child-Pugh B (n = 5) hepatic impairment scores completed this open-label and parallel study. They received 25 mg dexketoprofen (equivalent to 37 mg of its tromethamine salt) as a single (day 1) and a 3-day repeated dose (1 dose every 8 hours for a total of 10 doses). Dexketoprofen concentrations were determined in plasma and urine by reverse-phase high performance liquid chromatography (HPLC). Model-independent pharmacokinetic parameters were obtained. All subjects completed the study. No serious adverse events were recorded. Following the single dose, mean (+/- SEM) Cmax were 3027.7 +/- 429.3 ng/ml (healthy subjects), 2856.3 +/- 340.3 ng/ml (Child-Pugh A) and 1937.2 +/- 328.0 ng/ml (Child-Pugh B). Median tmax were 0.49 h (0.33-0.68) h, 0.50 h (0.33-0.67) h and 0.67 h (0.33-1.50) h. AUC0-x averaged 3778.0 +/- 439.0 ng.h/ml, 4890.4 +/- 539.1 ng.h/ml and 3985.0 +/- 712.0 ng.h/ml. Mean CL/F were 101.1 +/- 11.3 ml/h/kg, 73.3 +/- 9.9 ml/h/kg and 88.8 +/- 15.5 ml/h/kg and V/F averaged 0.192 +/- 0.018 l/kg, 0.162 +/- 0.006 l/kg and 0.214 +/- 0.044 l/kg. Following the repeated administration, similar results were obtained showing no drug accumulation. As related to the administered dose, median excretions of unchanged and conjugated dexketoprofen in urine were 2.1% and 67.1% in healthy subjects, 2.8% and 60.9% in Child-Pugh A subjects and 4.4% and 47.7% in Child-Pugh B volunteers. A trend towards a reduced urinary excretion of conjugated dexketoprofen in hepatic patients, more evident in the Child-Pugh B than in the Child-Pugh A groups, was observed when compared with healthy volunteers (median and 95% CI for differences: -5.4% [-19.9% to 2.0%] and -19.4% [-45.6% to 0.4%]). Conservatively, a dose adjustment of dexketoprofen trometamol in patients with impaired hepatic function is recommended.

Nepadutant pharmacokinetics and dose-effect relationships as tachykinin NK2 receptor antagonist are altered by intestinal inflammation in rodent models.

Tachykinin NK2 receptor antagonists could reduce motility and symptoms during gastrointestinal diseases characterized by local inflammation such as diarrhea or colitis; however, how these conditions change pharmacodynamic and pharmacokinetic characteristics of NK2 receptor antagonists is unknown. We investigated the effect of the peptide NK2 receptor antagonist nepadutant on spontaneous intestinal motility or [betaAla8]NKA(4-10)-induced colonic and bladder contractions in rodent models of intestinal inflammation (enteritis induced by castor oil and rectocolitis induced by local instillation of acetic acid in rats, enteritis induced by bacterial toxins in mice). In the castor oil model, the oral/intraduodenal bioavailability of nepadutant was also determined. The intrarectal (i.r.) administration of nepadutant (100 nmol/kg) did not reduce [betaAla8]NKA(4-10) (10 nmol/kg i.v.)-induced colonic and bladder contractions in normal animals, but the same dose of nepadutant produced an inhibitory effect in the two organs following rectocolitis; in contrast, nepadutant is equieffective by the intravenous route in normal and colitic animals. In this model, nepadutant (100 nmol/kg i.r. or i.v.) decreased spontaneous colonic hypermotility, without affecting motility in controls. The intraduodenal administration of nepadutant (30 nmol/kg), which was ineffective on [betaAla8]NKA(4-10) (10 nmol/kg i.v.)-induced colonic and bladder contractions in control animals, abolished bladder contractions in castor oil-pretreated animals. In this latter group, the oral and intraduodenal bioavailability of nepadutant showed a 7- to 9-fold increase with respect to controls. Oral administration of nepadutant, in nanomolar or subnanomolar dosage, reduced diarrhea induced by bacterial toxins in mice. It is concluded that intestinal inflammation increases nepadutant absorption in the intestine, enhancing its activity. These results suggest that a drug with a limited oral bioavailability could be used for treating gastrointestinal diseases associated with a local inflammation.

Pharmacokinetics of MEN-10755, a novel anthracycline disaccharide analogue, in two phase I studies in adults with advanced solid tumours.

The doxorubicin analogue MEN-10755 has been identified as a compound with promising antitumour activity based on structure-activity studies of a new series of anthracycline disaccharides. The high antitumour activity of MEN-10755 in human tumour xenografts, including doxorubicin-resistant xenografts, and its unique pharmacological and biological properties made this novel disaccharide analogue an interesting candidate for clinical evaluation. Two pharmacokinetic phase I studies with different dosing schedules were performed in adults with solid refractory malignancies. The pharmacokinetics of MEN-10755 were studied after a 15-min i.v. infusion given once every 3 weeks or once every week for 3 weeks followed by 1 week rest. Plasma and urine levels of MEN-10755 were measured by HPLC with fluorescent detection. It was possible to combine the pharmacokinetic results of the two studies because there was no accumulation of MEN-10755 before the next infusion of MEN-10755 in the weekly study with 1 week rest. The administered dose levels on day 1 in this study were all in the lower range from the 3-weekly study. The postinfusion plasma kinetics of MEN-10755 were best described by a triexponential model. The plasma peak levels (Cmax) of MEN-10755 showed a linear relationship with the administered dose. Peak plasma MEN-10755 levels ranged between 474 and 21,587 microg/l. The mean elimination half-life (T(1/2gamma)) was 20.7+/-9.0 h. The AUC(0-infinity) was proportional to the administered dose. The mean plasma clearance of MEN-10755 was 6.0+/-2.2 l/h per m2 with a mean volume of distribution (Vss) of 95.6+/-43.4 l/m2. The mean renal excretion of unchanged drug within 24 h was 4.3+/-1.8%. Compared to epirubicin and doxorubicin, the pharmacokinetics of MEN-10755 were characterized by an approximately twofold shorter terminal half-life, a much lower total plasma clearance and a much smaller volume of distribution.

Synthesis and biological activity of the penem antibiotic MEN 10700 and its orally absorbed ester MEN 11505.

The synthesis and biological properties of the new penem antibiotic MEN 10700 (6) and of its selected oral prodrug MEN 11505 (8f) are described. MEN 10700 showed a broad spectrum of activity, with high potency both on Gram-positive and Gram-negative strains. It also exhibited good antibacterial activity toward anaerobes and on strains selected for their resistance to other antibacterial agents (cefotaxime- or ceftazidime-resistant Gram-negative strains, ciprofloxacin-resistant E. coli, extended spectrum beta-lactamase producing and cephalosporinase inducible enterobacteria). MEN 10700 showed a very high stability to enzymatic degradation by renal dehydropeptidase DHP-I. After oral administration in rats of the pivaloyloxymethyl ester prodrug MEN 11505, the relative bioavailability of MEN 10700 was calculated as F=43%.

Mediator concentrations in bronchoalveolar lavage fluid of patients with mild asymptomatic bronchial asthma.

Bronchoalveolar lavage (BAL) was performed on 11 atopic patients with mild asymptomatic bronchial asthma and 11 healthy nonasthmatic volunteers. All asthmatic subjects had evidence of bronchial hyperresponsiveness to inhaled carbachol. The concentrations of leukotriene (LT) C4, LTD4, LTE4, LTB4, prostaglandin D2 (PGD2), platelet-activating factor (PAF) and histamine in BAL fluid measured. The leukotrienes were measured by radioimmunoassay following reverse phase high performance liquid chromatography. PGD2 concentrations were determined by radio immunoassay after Amprep C2 extraction. PAF was quantitated by means of in vitro aggregation of rabbit platelets and histamine content was measured using a single isotope radio-enzymatic assay. There was an increase in the levels of PGD2 and a decrease in the concentration of LTB4 in asthmatic lavage samples. There were no significant differences in the lavage concentrations of LTC4/D4/E4 and histamine between the two groups of individuals. PAF was undetectable.

Inhibition of leukotriene B4-induced neutrophil migration by lipoxin A4: structure-function relationships.

Lipoxins are trihydroxytetraene metabolites which are derived from arachidonic acid through an interaction between different lipoxygenase pathways. Previous work has shown that lipoxin A4 (LXA4) inhibits the chemotactic responsiveness of neutrophils (PMN) to leukotriene B4. We have now assessed the structural determinants of the lipoxin A4 molecule which are necessary for its inhibitory activity, using structural analogs of LXA4 prepared by chemical synthesis. Our results indicate the importance of two adjacent free hydroxyl groups in either the R or the S configuration; one hydroxyl group has to be in the C-6 position, but the other hydroxyl group can be in either the C-5 or the C-7 position for the conferment of inhibitory activity.

Effects of dietary fish oil lipids on allergic and inflammatory diseases.

Fish oil is rich in the polyunsaturated N-3 fatty acids, eicosapentaenoic (EPA) and docosahexaenoic acids (DCHA). EPA competes with arachidonic acid (AA) for metabolism by the cyclooxygenase and lipoxygenase pathways. Selective metabolites derived from EPA have reduced biological activities as compared with the AA-derived counterparts. Dietary supplementation with EPA led to incorporation of EPA into membrane phospholipids, an inhibition of 5-lipoxygenase pathway activity, and a reduction of the elaboration of platelet-activating factor. Neutrophil chemotaxis and the capacity of these cells to adhere to endothelial cells are substantially attenuated. This suggests that EPA has anti-inflammatory potential. Clinical trials in rheumatoid arthritis, psoriasis, atopic dermatitis, and bronchial asthma have shown beneficial effects. Whether the benefit obtained clinically is sufficient to replace or significantly reduce any clinical condition remains to be answered.

Sulphidopeptide leukotrienes in asthma.

Bronchial asthma is characterized by airways inflammation and airways hyperresponsiveness. It is unlikely that the pathophysiology of asthma and bronchial hyperresponsiveness can be explained on the basis of a single cell or a single class of mediators. Nevertheless, the possibility that leukotrienes may contribute to the pathogenesis of the inflammatory, vasoactive ans spasmogenic components of bronchial asthma is suggested by the properties of these lipid mediators, the preferential capacity of inflammatory cells to generate leukotrienes and the presence of leukotrienes in the airways of asthmatic subjects. The sulphidopeptide leukotrienes are potent bronchoconstrictor agonists when inhaled. The airways of asthmatic subjects are hyperresponsive to leukotrienes as to other bronchoconstrictor agonists. Nevertheless, the airways responsiveness of asthmatic subjects to these agonists demonstrate several unusual properties. While the airways of asthmatic subjects are relatively less responsive to LTC4 and LTD4, compared to agents such as histamine or methacholine, they demonstrate a marked and selective hyperresponsiveness to LTE4, suggesting a possibly unique role for this mediator in the pathogenesis of airways hyperresponsiveness. In addition an increased sensitivity of the airways to LTE4 may contribute to the mechanism of aspirin-induced asthma. The capacity of the sulphidopeptide leukotrienes to increase the airways responsiveness of normal subjects to methacholine and of asthmatic subjects to histamine is further evidence for a role for these substances in the pathogenesis of bronchial asthma.

Asthmatic airways have a disproportionate hyperresponsiveness to LTE4, as compared with normal airways, but not to LTC4, LTD4, methacholine, and histamine.

Airways responsiveness to leukotriene (LT) C4, LTD4, LTE4, histamine, and methacholine have been studied in eight asthmatic and six normal subjects. Airways responsiveness to each bronchoconstrictor agonist was assessed by constructing cumulative dose-response curves, and the dose that produced a 35% decrease in specific airways conductance (PD35) was obtained by linear interpolation. Airways of subjects with asthma were approximately 14-, 15-, 6-, 9-, and 219-fold more responsive to histamine, methacholine, LTC4, LTD4, and LTE4, respectively, than were normal subjects. Thus, there was a substantially augmented level of hyperresponsiveness to LTE4 in bronchial asthma, which was not observed for the other bronchoconstrictor agents, when compared to normal subjects. In contrast to LTC4 and LTD4, as histamine and methacholine responsiveness increase, the dose ratio of histamine to LTE4 (PD35 histamine/PD35 LTE4) and the dose ratio of methacholine to LTE4 also tended to increase. This suggests that as the nonspecific airways responsiveness increases, the relative potency of LTE4 also increases, whereas potency of LTC4 and LTD4 decrease. These results suggest that the mechanism of the bronchoconstriction induced by LTE4 may be distinct from that produced by LTC4 or LTD4 in subjects with asthma. This may reflect leukotriene subtype receptor heterogeneity in asthmatic airways.

Identification of lipoxin A4 and its relationship to the sulfidopeptide leukotrienes C4, D4, and E4 in the bronchoalveolar lavage fluids obtained from patients with selected pulmonary diseases.

Lipoxins are biologically active trihydroxytetraene containing products derived from arachidonic acid that are formed by interactions between lipoxygenases. Although the lipoxins have been generated from mixed cell suspensions in vitro, it has not been established whether these products are synthesized in vivo. We have performed bronchoalveolar lavage (BAL) in 12 patients with lung disease (sarcoid, six; pneumonia, two; asthma, two; carcinoma, one; alveolitis of unknown cause, one) and in six normal control subjects. The BAL fluid was analyzed for lipoxin A4 (LXA4) using gas chromatography mass spectrometry with selective ion monitoring, and the levels of the sulfidopeptide leukotrienes were determined using reverse-phase high-performance liquid chromatography and radioimmunoassay. LXA4 was detected in BAL fluid from nine of the 12 patients studied. The levels of LXA4 ranged from 0.4 to 2.8 ng/ml. LXA4 was not detected in any of the six normal subjects. Sulfidopeptide leukotrienes were detected in all the BAL samples, ranging from 0.04 to 0.7 ng/ml, and there was no significant difference between the patients and the normal subjects. In patients with detectable LXA4 in BAL fluid, the ratio of the concentrations of LXA4 to those of the sulfidopeptide leukotrienes ranged from 1.9 to 62 (mean, 19.0). This is the first demonstration of the presence of LXA4 in disease.

Lipoxin A4 inhibits phosphoinositide hydrolysis in human neutrophils.

Lipoxins (LX) are trihydroxytetraene metabolites derived from arachidonic acid via an interaction between the 5- and 15-lipoxygenases. Preincubation of [3H] myo-inositol labeled PMN with 10-7M and 10-5M LXA4 for 1 minute at 37 degrees C resulted in a concentration dependent inhibition of the generation of [3H] IP3 and [3H] IP in cells subsequently stimulated by increasing doses of LTB4 or FMLP for 1 minute at 37 degrees C. Preincubation of PMN with LXA4 did not inhibit specific binding of [3H] LTB4 to PMN. These results indicate that LXA4 inhibits chemotactic factor-induced phosphoinositide hydrolysis at a post-receptor level.

Contractile and binding activities of structural analogues of LTC4 in the longitudinal muscle of guinea-pig ileum.

High affinity binding sites for LTC4 have been identified in various tissues, including guinea-pig ileal longitudinal muscle. More recently, it has been shown that LTC4 binds to non-receptor sites as well, particularly to glutathione transferases. In the present study, LTC4 and 9 chemically synthesized analogues, as well as the SRS-A antagonist FPL 55712 and S-decyl-glutathione, were tested for their ability to inhibit 3H-LTC4 binding in membranes from guinea-pig ileal longitudinal muscle and to affect the tone of the ileum in vitro. A significant correlation between binding and contractile activities was found for the LTC4 analogues and FPL 55712. However, S-decyl-glutathione, although possessing some affinity for LTC4 binding sites, was devoid of any effect on guinea-pig ileum tone at least up to 10(-5) M, thus indicating that these sites cannot be functional receptors, although they may represent other units involved in leukotriene action, e.g. uptake sites.