Laparoscopic liver resection of benign liver tumors

OBJECTIVE

The objective of this study was to assess the feasibility, safety, and outcome of laparoscopic liver resection for benign liver tumors in a multicenter setting.

BACKGROUND

Despite restrictive, tailored indications for resection in benign liver tumors, an increasing number of articles have been published concerning laparoscopic liver resection of these tumors.

METHODS

A retrospective study was performed in 18 surgical centres in Europe regarding their experience with laparoscopic resection of benign liver tumors. Detailed standardized questionnaires were used that focused on patient's characteristics, clinical data, type and characteristics of the tumor, technical details of the operation, and early and late clinical outcome.

RESULTS

From March 1992 to September 2000, 87 patients suffering from benign liver tumor were included in this study: 48 patients with focal nodular hyperplasia (55%), 17 patients with liver cell adenoma (21%), 13 patients with hemangioma (15%), 3 patients with hamartoma (3%), 3 patients with hydatid liver cysts (3%), 2 patients with adult polycystic liver disease (APLD) (2%), and 1 patient with liver cystadenoma (1%). The mean size of the tumor was 6 cm, and 95% of the tumors were located in the left liver lobe or in the anterior segments of the right liver. Liver procedures included 38 wedge resections, 25 segmentectomies, 21 bisegmentectomies (including 20 left lateral segmentectomies), and 3 major hepatectomies. There were 9 conversions to an open approach (10%) due to bleeding in 45% of the patients. Five patients (6%) received autologous blood transfusion. There was no postoperative mortality, and the postoperative complication rate was low (5%). The mean postoperative hospital stay was 5 days (range, 2-13 days). At a mean follow-up of 13 months (median, 10 months; range, 2-58 months), all patients are alive without disease recurrence, except for the 2 patients with APLD.

CONCLUSIONS

Laparoscopic resection of benign liver tumors is feasible and safe for selected patients with small tumors located in the left lateral segments or in the anterior segments of the right liver. Despite the use of a laparoscopic approach, selective indications for resection of benign liver tumors should remain unchanged. When performed by expert liver and laparoscopic surgeons in selected patients and tumors, laparoscopic resection of benign liver tumor is a promising technique.

Biphenyl derivatives as novel dual NK(1)/NK(2)-receptor antagonists

In a continuation of our efforts to simplify the structure of our neurokinin antagonists, a series of substituted biphenyl derivatives has been prepared. Several compounds exhibit potent affinities for both the NK(1) receptor (<10nM) and for the NK(2) receptor (<50 nM). Details on the design, synthesis, biological activities, SAR and conformational analysis of this new class of dual NK(1)/NK(2) receptor antagonists are presented.

Laparoscopic liver resection for malignant liver tumors: preliminary results of a multicenter European study

OBJECTIVE

To assess the feasibility, safety, and outcome of laparoscopic liver resection for malignant liver tumors.

SUMMARY BACKGROUND DATA

The precise role of laparoscopy in resection of liver malignancies (hepatocellular carcinoma [HCC] and liver metastases) remains controversial despite an increasing number of publications reporting laparoscopic resection of benign liver tumors.

METHODS

A retrospective study was performed in 11 surgical centers in Europe regarding their experience with laparoscopic resection of liver malignancies. Detailed questionnaires were sent to each surgeon focusing on patient characteristics, clinical data, type and characteristics of the tumor, technical details of the operation, and early and late clinical outcome. All patients had radiologic investigations at follow-up to exclude disease recurrence.

RESULTS

From February 1994 to December 2000, 37 patients with malignant liver tumors were included in this study. Ten patients had HCC, including 9 with cirrhotic liver, and 27 patients had liver metastases. The mean tumor size was 3.3 cm, and 89% of the tumors were located in the left lobe or in the anterior segments of the right liver. Liver procedures included 12 wedge resections, 9 segmentectomies, 14 bisegmentectomies (including 13 left lateral segmentectomies), and 2 major hepatectomies. The transfusion rate, the use of pedicular clamping, the conversion rate (13.5% in the whole series), and the complication rate were significantly greater in patients with HCC. There were no deaths. Postoperative complications occurred in eight patients (22%). The surgical margin was less than 1 cm in 30% of the patients. During a mean follow-up of 14 months, the 2-year disease-free survival was 44% for patients with HCC and 53% for patients having hepatic metastases from colorectal cancer. No port-site metastases were observed during follow-up.

CONCLUSIONS

In patients with small malignant tumors, located in the left lateral segments or in the anterior segments of the right liver, laparoscopic resection is feasible and safe. The complication rate is low, except in patients with HCC on cirrhotic liver. By using laparoscopic ultrasound, a 1-cm free surgical margin should be routinely obtained. The late outcome needs to be evaluated in expert centers.

[Micro-angiopathic and psychological risk in children and adolescents with type 1 diabetes]

OBJECTIVE

Evaluate the correlation between psychopathological disorders in type 1 insulin-dependent diabetic (IDD) children and adolescents and the occurrence of micro-angiopathic complications.

METHODS

Two hundred and five IDD children (104 girls and 101 boys with a mean age of 13.4 +/- 3.5 years on inclusion) were longitudinally monitored between 1994 and 2000. Somatic complications were systematically searched for during a yearly control visit to the day hospital. Psychiatric disorders had been assessed initially by self-administered questionnaires filled-in by the children (Spielberger's STAIC-Trait for anxiety, CESD for depression and Child-EAT for eating habits), by the parents (CBCL, CPRS or GHQ-28) or the principle teachers (CTRS) and diagnostic screening of psychopathological disorders every year.

RESULTS

More than 140% of the IDD children (n = 86) were diagnosed DSM-IV, with predominant anxiety (n = 41), during the longitudinal evaluation. Positive screening was significantly associated with higher psychopathological scores before inclusion in the study, with children considered more perturbed by the parents, teachers and the children themselves and mothers who considered themselves more perturbed (GHQ-28 mean 5.6 +/- 7.5 vs. 3.5 +/- 4.8; t = 2.211 p = 0.028). These children were less compliant. Disorders were associated with metabolic imbalance, measured by HbA1c, overweight and an excess of micro-angiopathic, particularly retinopathic, complications.

CONCLUSION

Our results show the frequency of mental disorders in IDD children, the importance of the parents' psychopathology and its association with increased somatic risk. The nature of this relationship requires clarification and the incidence of prevention measures targeted on the psychological problems. The interest of associating a paedopsychiatric element in the therapeutic management of these patients and their families is emphasized.

MRI prior computation and parallel tempering algorithm: a probabilistic resolution of the MEG/EEG inverse problem

Since the MEG inverse problem is ill-posed and admits many possible solutions, it is not possible to give it a single "true" answer. Therefore, we propose here to use a specific probabilistic algorithm to map the full probability distribution of the MEG sources with Markov Chain Monte Carlo methods. Using a Bayesian approach, the probability of the MEG solutions is expressed as the product of the likelihood by the prior probability. To compute the prior and constrain the MEG inverse problem resolution, MRI data are also acquired and automatically processed to determine the brain position and volume. We then use Parallel Tempering algorithm to estimate the full posterior probability and determine the likely solutions of the inverse problem. We illustrate the method with results obtained from the analysis of somatosensory data. This illustrates both the MRI processing for the prior computation, and how the knowledge of the full posterior probability distribution can be used to estimate the position of the sources, as well as their likely extension.

Constituents of Pilocarpus trachylophus

Four flavonoids, two terpenoids and a mixture of three polyprenols have been isolated from the leaves of Pilocarpus trachylophus.

[Obesity in children and adolescents, mental disorders and familial psychopathology]

OBJECTIVE

The purpose of this study was to evaluate the type and frequency of psychopathological disorders observed in obese children and adolescents. We also looked for a correlation between psychic disorders in the obese children, the degree of obesity and paternal psychopathology.

PATIENTS AND METHODS

The study group included 84 obese children and adolescents aged 5 to 16 years (mean age 10.9 +/- 2.8 years). There were 55 girls and 29 boys. The z-score expressing deviation from the ideal body mass index (IMC) varied from +2 to +10.6 (mean 4 + 1.9). Psychopathological disorders observed in these obese patients were compared in children and adolescents with insulin-dependent diabetes mellitus. The standard diagnostic interview (K-SADS PL) and self-administered questionnaires (Sielberger STAIC-Trait for anxiety and CDI for depression in children or CBCL or GHQ for their parents) were also used to evaluate psychic disorders.

RESULTS

More than half of the obese children (47 out of 84) had a DSM-IV diagnosis, often involving anxiety (n = 28). The rate of internalized and externalized psychopathological disorders (measured by STAIC-Trait and CBCL) was higher in the obese children than in the diabetics. The children's psychopathological disorders were more marked if their parents were perturbed, particularly when their mother had an internalized disorder. No correlation was found between the degree obesity and psychopathological disorders in the obese children and adolescents.

CONCLUSION

Our findings show the frequency of mental disorders in obese children and point out the importance of parental psychopathology. This underlines the usefulness of a pedopsychiatric approach implicating the entire family for therapeutic management of these patients.

Identification of the alkaloids of Galipea officinalis by gas chromatography-mass spectrometry

Galipea officinalis Hancock, a Venezuelan shrubby tree which is acclaimed in folk medicine for its many healing properties, is the only species of the genus to contain tetrahydroquinoline alkaloids. A GC-MS method has been developed in order to analyse the essential oil, hexane and chloroform extracts of the trunk bark of this plant, without prior derivatisation of the alkaloidal components. A study of the MS fragmentation patterns of the components permitted the identification of five new minor quinoline alkaloids together with the known alkaloids. In addition, the method could also be used for the characterisation of alkaloids within the genus Galipea.

Comorbidity of post-traumatic stress disorder and chronic pain: implications for clinical and forensic assessment

A summary of the current state of science is presented with reference to post-traumatic stress disorder (PTSD) and pain. Historical development of the diagnosis, current nosology, epidemiology, pathophysiology, and controversies are discussed. Issues of evaluation are reviewed, with specific reference to forensic assessment. Treatment outcome studies are briefly reviewed, with a review of currently accepted treatment interventions, including pharmacologic and behavioral modalities. An emphasis is placed on an integrated treatment plan in which chronic pain and PTSD both are present.

IL-5 deficiency abolishes aspects of airway remodelling in a murine model of lung inflammation

BACKGROUND AND OBJECTIVES

Lung remodelling is a recognized feature of chronic asthma. In the present study, we have used IL-5-deficient mice to evaluate the role of this cytokine and eosinophilic inflammation in the initial stages of the structural changes occurring in the lung after antigen challenge.

METHODS

Ovalbumin-sensitized wild type and IL-5-deficient mice were daily challenged for 5 consecutive days and killed 3 or 7 days after the last challenge to study the inflammatory and remodelling events, respectively.

RESULTS

Wild type mice challenged with ovalbumin exhibited an accumulation of eosinophils in the bronchoalveolar lavage (BAL) fluid, associated with a production of BAL cellular fibronectin. Histological analysis also revealed an antigen-specific increase in epithelial and alveolar cell proliferation together with an increase in mucus producing epithelial cells. Eosinophilic infiltration and the associated lung remodelling were totally abrogated in IL-5-deficient mice. In wild type mice, treated intranasally with 1 microg of murine IL-5 for 5 consecutive days, no BAL eosinophilia and structural changes of the lungs could be observed.

CONCLUSION

Our results demonstrate that eosinophil accumulation, but not IL-5 alone, plays a central role in the initial stages of the lung remodelling process and suggests that therapies directed at inhibiting eosinophilic inflammation may be beneficial in treating chronic asthma.

A probabilistic solution to the MEG inverse problem via MCMC methods: the reversible jump and parallel tempering algorithms

We investigated the usefulness of probabilistic Markov chain Monte Carlo (MCMC) methods for solving the magnetoencephalography (MEG) inverse problem, by using an algorithm composed of the combination of two MCMC samplers: Reversible Jump (RJ) and Parallel Tempering (PT). The MEG inverse problem was formulated in a probabilistic Bayesian approach, and we describe how the RJ and PT algorithms are fitted to our application. This approach offers better resolution of the MEG inverse problem even when the number of source dipoles is unknown (RJ), and significant reduction of the probability of erroneous convergence to local modes (PT). First estimates of the accuracy and resolution of our composite algorithm are given from results of simulation studies obtained with an unknown number of sources, and with white and neuromagnetic noise. In contrast to other approaches, MCMC methods do not just give an estimation of a "single best" solution, but they provide confidence interval for the source localization, probability distribution for the number of fitted dipoles, and estimation of other almost equally likely solutions.

The laser welding technique applied to the non precious dental alloys procedure and results

AIM

The laser welding technique was chosen for its versatility in the repair of dental metal prosthesis. The aim of this research is to assess the accuracy, quality and reproducibility of this technique as applied to Ni-Cr-Mo and Cr-Co-Mo alloys often used to make prosthesis

METHOD

The alloy's ability to weld was evaluated with a pulsed Nd-Yag Laser equipment. In order to evaluate the joining, various cast wires with different diameters were used. The efficiency of the joining was measured with tensile tests. In order to understand this difference, metallographic examinations and X-Ray microprobe analysis were performed through the welded area and compared with the cast part.

RESULTS

It was found that a very slight change in the chemistry of the Ni-Cr alloys had a strong influence on the quality of the joining. The Co-Cr alloy presented an excellent weldability. A very important change in the microstructure due to the effect of the laser was pointed out in the welding zone, increasing its micro-hardness.

CONCLUSION

The higher level of carbon and boron in one of the two Ni-Cr was found to be responsible for its poor welding ability. However for the others, the maximum depth of welding was found to be around 2mm which is one of the usual thicknesses of the components which have to be repaired.

Expression of the high molecular weight fibroblast growth factor-2 isoform of 210 amino acids is associated with modulation of protein kinases C delta and epsilon and ERK activation

The high molecular weight (HMW) fibroblast growth factor (FGF)-2 isoform of 210 amino acids initiated at a CUG start codon possesses a nuclear localization sequence and is not secreted. In contrast, the low molecular weight (LMW) isoform of 155 amino acids initiated at the AUG start codon can be secreted and activates the cell surface FGF receptors. The two isoforms possess different biological properties; however, little is known about the intracrine regulatory mechanisms involved in the biological effects of the HMW FGF-2 isoform. Using pancreatic cells stably transfected with cDNAs leading to the expression of either the HMW FGF-2 (A3 cells) or the LMW form (A5 cells), we provide evidence that the two FGF-2 isoforms differentially modulate PKC levels. The LMW FGF-2 up-regulated the PKC epsilon levels by 1.6-fold; by contrast the HMW isoform down-regulated the level of this PKC isotype by about 3-fold and increased the amount of PKC delta by 1.7-fold. PKC mRNAs were also modified, suggesting that PKC expression was regulated at a pretranslational level. Additionally, expression of different levels of the HMW FGF-2 with an inducible expression system confirmed the role of this isoform on PKC delta and epsilon expressions. Increased activation of ERK-1 and -2 was also observed in cells expressing the HMW FGF-2. By using different PKC inhibitors and a dominant negative PKC delta, it was found that ERK activation was PKC delta-dependent. These data indicate that expression of HMW FGF-2 can modify PKC levels by acting at the intracellular level and that the overexpression of PKC delta induces ERK-1/2 activation. The expression of a dominant negative FGFR1 did not reduce ERK-1/2 activation by the HMW FGF-2, suggesting that ERK activation does not require FGFR activity. The signaling cascade downstream of ERK might be involved in the known mitogenic effect exerted by this FGF-2 isoform.

Zebrafish acetylcholinesterase is encoded by a single gene localized on linkage group 7. Gene structure and polymorphism; molecular forms and expression pattern during development

We cloned and sequenced the acetylcholinesterase gene and cDNA of zebrafish, Danio rerio. We found a single gene (ache) located on linkage group LG7. The relative organization of ache, eng2, and shh genes is conserved between zebrafish and mammals and defines a synteny. Restriction fragment length polymorphism analysis was allowed to identify several allelic variations. We also identified two transposable elements in non-coding regions of the gene. Compared with other vertebrate acetylcholinesterase genes, ache gene contains no alternative splicing at 5' or 3' ends where only a T exon is present. The translated sequence is 60-80% identical to acetylcholinesterases of the vertebrates and exhibits an extra loop specific to teleosts. Analysis of molecular forms showed a transition, at the time of hatching, from the globular G4 form to asymmetric A12 form that becomes prominent in adults. In situ hybridization and enzymatic activity detection on whole embryos confirmed early expression of the acetylcholinesterase gene in nervous and muscular tissues. We found no butyrylcholinesterase gene or activity in Danio. These findings make zebrafish a promising model to study function of acetylcholinesterase during development and regulation of molecular forms assembly in vivo.

Time course of inflammatory and remodeling events in a murine model of asthma: effect of steroid treatment

The kinetics of airway inflammation and remodeling processes following ovalbumin aerosol challenge in sensitized BALB/c mice was studied. Mice were exposed to either single or five ovalbumin challenges over 5 days. In both protocols, time-dependent increases in bronchoalveolar lavage (BAL) cellular fibronectin, neutrophils and eosinophils were observed. The kinetics of these events were similar in both protocols; however, the magnitude of the response was much greater following repeated challenges. BAL protein levels and lymphocyte numbers were increased only following repeated challenges, whereas interleukin (IL)-5 and IL-4 were increased in both protocols. Histological analysis revealed a time-dependent increase in epithelial cell proliferation and in mucus-producing epithelial cells. Proliferation of alveolar cells was observed only following repeated challenges. Airway hyperreactivity was observed in both protocols but was much greater following repeated challenges. Pretreatment with dexamethasone fully inhibited the inflammatory response and airway hyperreactivity but only partially inhibited the remodeling process. These data suggest that glucocorticoids, although potent anti-inflammatory agents, may not be potent in reducing the lung remodeling process associated with asthma.

[Assessment of quality of life after antireflux surgery]

AIM OF THE STUDY

To assess the quality of life (QoL) of patients operated for gastroesophageal reflux disease (GERD).

PATIENTS AND METHODS

This prospective study included 82 consecutive patients submitted to antireflux surgery between October 1998 and January 1999. A new questionnaire was used to assess their QoL: the Gastrointestinal Quality of Life Index (GIQLI) that includes 36 items concerning 5 dimensions: symptoms, vitality, emotions, social relations and medical treatment. The series consisted of 44 men and 38 women with a mean age of 47 years (range: 18-78). QoL was assessed before and 6 months after surgery; the follow-up rate was 94% (77/82). The pre- and postoperative GIQLI scores of the study group and the GIQLY score of a control group of 110 healthy patients were compared.

RESULTS

Before surgery, the GIQLI score (90 +/- 23) was greatly impaired compared to the score (123 +/- 13) observed in the control group (p < 0.001). After surgery, the GIQLI score (110 +/- 23) increased significantly (p < 0.001), but remained statistically lower than the score of the control group (p < 0.001). The postoperative score recorded in the symptoms dimension was lower than the control group score: 55 +/- 11 versus 66 +/- 6 (p < 0.001), while no significant difference was observed in the other 4 dimensions. Univariate statistical analysis revealed that the postoperative GIQLI score (y) was correlated with the preoperative GIQLI score (x) according to the formula: y = 0.43 x + 71 (p < 0.001) and the sex of the patients, as the postoperative GIQLI score was higher in male patients (115 +/- 19) than in female patients (103 +/- 23) (p < 0.02).

CONCLUSION

The QoL of the patients was greatly improved after antireflux surgery, but remained lower than that of a control group of healthy subjects. Better patient selection should improve the results. In our series, male patients or patients with a high preoperative GIQLI score were the best candidates for antireflux surgery.

Inducible nitric oxide synthase inhibitors suppress airway inflammation in mice through down-regulation of chemokine expression

Growing evidence demonstrates that inducible NO synthase (iNOS) is induced in the airways of asthmatic patients. However, the precise role of NO in the lung inflammation is unknown. This study investigated the effect of both selective and nonselective iNOS inhibitors in an allergen-driven murine lung inflammation model. OVA challenge resulted in an accumulation of eosinophils and neutrophils in the airways. Expression of iNOS immunostaining in lung sections together with an increase in calcium-independent NOS activity in lung homogenates was also observed after OVA challenge. Treatment with iNOS inhibitors from the day of challenge to the day of sacrifice resulted in an inhibition of the inflammatory cell influx together with a down-regulation of macrophage inflammatory protein-2 and monocyte chemoattractant protein-1 production. In contrast, eosinophilic and neutrophilic inhibition was not observed with treatment during the sensitization. Both treatments induced an increased production of Th2-type cytokines (IL-4 and IL-5) with a concomitant decrease in production of Th1-type cytokine (IFN-gamma). In vitro exposure of primary cultures of murine lung fibroblasts to a NO donor, hydroxylamine, induced a dose-dependent release of macrophage inflammatory protein-2 and monocyte chemoattractant protein-1. Our results suggest that lung inflammation after allergen challenge in mice is partially dependent on NO produced mainly by iNOS. NO appears to increase lung chemokine expression and, thereby, to facilitate influx of inflammatory cells into the airways.

N-[(R,R)-(E)-1-(4-chloro-benzyl)-3-(2-oxo-azepan-3-ylcarbamoyl)-allyl]-N-methyl-3,5-bis-trifluoromethyl-benzamide: an orally active neurokinin NK1/NK2 antagonist

The stereoselective synthesis of N-[(R,R)-(E)-1-(4-chloro-benzyl)-3-(2-oxo-azepan-3-ylcarbamoyl+ ++)-allyl]-N-methyl-3,5-bis-trifluoromethyl-benzamide (4) and its NK1 and NK2 receptor binding properties are reported. In addition the potent inhibitory effects in vivo on sar9-SP- and beta-Ala-NKA-induced airway bronchoconstriction in guinea pigs are demonstrated.

Presence and bronchomotor activity of protease-activated receptor-2 in guinea pig airways

The protease activated receptor-2 (PAR-2) belongs to a family of G-protein-coupled receptors that are activated by proteolysis. Trypsin cleaves PAR-2, exposing an N-terminal tethered ligand (SLIGRL) that activates the receptor. Messenger RNA (mRNA) for PAR-2 was found in guinea pig airway tissue by reverse transcription-polymerase chain reaction, and PAR-2 was found by immunohistochemistry in airway epithelial and smooth-muscle cells. In anesthetized guinea pigs, trypsin and SLIGRL-NH(2) (given intratracheally or intravenously) caused a bronchoconstriction that was inhibited by the combination of tachykinin-NK(1) and -NK(2) receptor antagonists and was potentiated by inhibition of nitric oxide synthase (NOS). Trypsin and SLIGRL-NH(2) relaxed isolated trachea and main bronchi, and contracted intrapulmonary bronchi. Relaxation of main bronchi was abolished or reversed to contraction by removal of epithelium, administration of indomethacin, and NOS inhibition. PAR-1, PAR-3, and PAR-4 were not involved in the bronchomotor action of either trypsin or SLIGRL-NH(2), because ligands of these receptors were inactive either in vitro or in vivo, and because thrombin (a PAR-1 and PAR-3 agonist) did not show cross-desensitization with PAR-2 agonists in vivo. Thus, we have localized PAR-2 to the guinea-pig airways, and have shown that activation of PAR-2 causes multiple motor effects in these airways, including in vivo bronchoconstriction, which is in part mediated by a neural mechanism.

PLA2 phosphorylation and cyclooxygenase-2 induction, through p38 MAP kinase pathway, is involved in the IL-1beta-induced bradykinin B2 receptor gene transcription

We hypothesized that inflammatory mediators such as interleukin-1beta (IL-1beta) might be responsible for the hyperreactivity to bradykinin observed in asthmatic patients. We reported previously that IL-1beta induced a prostanoid-dependent increase in the density of bradykinin B2 receptors in cultured human bronchial smooth muscle cells. Our experiments demonstrate that the rapid prostaglandin E2 (PGE2) synthesis induced by IL-1beta is abolished by cycloheximide, suggesting the involvement of protein synthesis. The formation of PGE2 is preceded by the phosphorylation of cPLA2 and the expression of cyclooxygenase-2 (Cox-2). The inhibition of p38 MAP kinase inhibited PGE2 synthesis, cPLA2 phosphorylation and abolished Cox-2 expression. The inhibition of Cox-2 expression correlated with a decrease of bradykinin B2 receptor expression. These data demonstrate that the activation of p38 MAP kinase elicited by IL-1beta leads to the phosphorylation of cPLA2 and Cox-2 overexpression, allowing rapid synthesis of PGE2 as a prerequisite for bradykinin B2 gene expression in human bronchial smooth muscle cells which could explain the hyperresponsiveness of asthmatic patients to bradykinin.

Role of nitric oxide and septide-insensitive NK(1) receptors in bronchoconstriction induced by aerosolised neurokinin A in guinea-pigs

The tachykinin, neurokinin A (NKA), contracts guinea-pig airways both in vitro and in vivo, preferentially activating smooth muscle NK(2) receptors, although smooth muscle NK(1) receptors may also contribute. In vitro evidence suggests that NKA activates epithelial NK(1) receptors, inducing the release of nitric oxide (NO) and subsequent smooth muscle relaxation. A number of selective NK(1) receptor agonists have been reported to activate both smooth muscle and epithelial NK(1) receptors, however septide appears only to activate smooth muscle NK(1) receptors. The aim of the present study was to investigate whether NKA-induced bronchoconstriction in guinea-pigs in vivo may be limited by NO release via NK(1) receptor activation, and whether selective NK(1) receptor agonists may activate this mechanism differently. Aerosolized NKA caused an increase in total pulmonary resistance (RL) that was markedly reduced by the NK(2) receptor antagonist, SR 48968, and abolished by the combination of SR 48968 and the NK(1) receptor antagonist, CP-99, 994. The increase in RL evoked by NKA was potentiated by pretreatment with the NO synthase (NOs) inhibitor, L-NAME, but not by the inactive enantiomer D-NAME. Potentiation by L-NAME of NKA-induced increase in RL was reversed by L-Arginine, but not by D-Arginine. Pretreatment with L-NAME did not affect the increase in RL induced by the selective NK(2) receptor agonist, [beta-Ala(8)]NKA(4-10), and by the selective NK(1) receptor agonist, septide, whereas it markedly potentiated the increase in RL caused by a different NK(1) selective agonist, [Sar(9),Met(O(2))(11)]SP. Dose-response curves showed that septide was a more potent bronchoconstrictor than [Sar(9),Met(O(2))(11)]SP to cause bronchoconstriction. Pretreatment with the NK(1) receptor antagonist, CP-96,994, abolished the ability of L-NAME to increase bronchoconstriction to aerosolized NKA. Bronchoconstriction to aerosolized NKA was increased by L-NAME, after pretreatment with the NK(3) receptor antagonist, SR 142801. The present study shows that in vivo bronchoconstriction in response to the aerosolized naturally occurring tachykinin, NKA, is limited by its own ability to release relaxant NO via NK(1) receptor activation. This receptor is apparently insensitive to septide, thus justifying, at least in part, the high potency of septide to cause bronchoconstriction in guinea-pigs.