Anogenital lichen sclerosus et atrophicus lesions in a case series of cancer patients on immunotherapy.

Lichenoid reactions are one of the most frequently observed toxicities with anticancer agents and, recently, a rapid emergence of immunotherapies in oncology has hastened the need to better characterize their unique toxicity profiles, particularly for less common skin toxicities, including anogenital lichen sclerosus et atrophicus (LSA). This case series describes four patients with advanced cancer (one melanoma, two lung cancers, and one kidney tumor) developing LSA lesions while receiving an immunotherapy. Medical records from 2017 to 2020 were retrospectively reviewed. Two patients received pembrolizumab, anti-programmed cell death-1 (PD-1), one nivolumab, anti-programmed cell death-1 (PD-1), and one ipilimumab, an immune checkpoint inhibitor. LSA emerged after a median of 3 months (range, 2-4 months) from starting immunotherapy. All LSA cases were grade 2. Three cases occurred on the penis and one case on the anus. All patients improved after a specific treatment for LSA, and no LSA-related antineoplastic treatment interruption/life-threatening condition were reported. To date, this is the first case series of LSA lesions associated with immunotherapy. Early LSA recognition and management is helpful in cancer patients on immunotherapy allowing a long survival and treatment response.

A comparative dermoscopic and reflectance confocal microscopy study of naevi and melanoma with negative pigment network.

BACKGROUND: Negative pigment network (NPN) is a dermoscopic structure observed more frequently among melanomas than naevi. Precise tissue correlates of NPN are still elusive. OBJECTIVE: To describe the reflectance confocal microscopy (RCM) findings underlying NPN in melanocytic neoplasms. METHODS: We retrospectively identified all melanocytic neoplasms displaying dermoscopic NPN that were imaged with RCM and subsequently biopsied between 2011 and 2015. Images from study lesions (n = 50) were evaluated for dermoscopic and RCM Criteria. Histopathological correlational study was performed in a subset of cases (n = 15). RESULTS: The study data set consisted of 21 melanomas (42%) and 29 naevi (58%). Melanomas showed more frequently irregularly shaped globules than naevi (62% vs. 28%, P = 0.03); NPN also tended to be more asymmetrically located among melanomas (86%) than naevi (62%), albeit not significant (P = 0.06). Under RCM, we observed three patterns of dermal papillae (DP): (i) 'Dark DP' - whereby DP were devoid of nests and often surrounded by a junctional proliferation as thick-Rings - this pattern was less common among melanomas (n = 10, 48%) than naevi (n = 23, 79%, P = 0.02); (ii) 'Bulging DP' - whereby junctional nests of melanocytes protrude into the DP, often in association with junctional proliferation as Meshwork - with comparable frequency among melanomas (n = 12, 57%) and naevi (n = 23, 79%, P = 0.09) and (iii) 'Expanded DP' - whereby junctional and/or dermal nests filled and expanded the DP, often in association with dermal-epidermal junction (DEJ) Clod pattern - seen more commonly among melanomas (n = 15, 71%) than naevi (n = 6, 21%, P < 0.001). Dermoscopy-RCM correlation and comparison to histopathological findings show that the hypo-pigmented lines of NPN correlate with broadened epidermal retes, which often show overlying surface dells and wedge-shaped hypergranulosis, while the pigmented globules of NPN correlate with a predominantly-junctiona of melanocytes along and between the elongated retes. CONCLUSIONS: Dermoscopic NPN correlates with three DEJ RCM patterns with differing frequency between naevi and melanomas.

Morphological classification of melanoma metastasis with reflectance confocal microscopy.

BACKGROUND: Cutaneous malignant melanoma metastases differential diagnosis is challenging, as clinical and dermoscopic features can simulate primary melanoma or other benign or malignant skin neoplasms, and in-vivo reflectance confocal microscopy could assist. Our aim was to identify specific reflectance confocal microscopy features for cutaneous malignant melanoma metastases, and epidermal and dermal involvement. METHODS: A retrospective, multicentre observational study of lesions with proven cutaneous malignant melanoma metastases diagnosis between January 2005 and December 2016. Lesions were retrospectively assessed according to morphological features observed at reflectance confocal microscopy. Potential homogeneous subgroups of epidermal or dermal involvement were investigated with cluster analysis. RESULTS: Cutaneous malignant melanoma metastases (51 lesions in 29 patients) exhibited different frequencies of features according to metastasis dermoscopy patterns. Lesions classified at dermoscopy with nevus-like globular and non-globular patterns were more likely to be epidermotropic, showing characteristics of epidermal and dermal involvement at reflectance confocal microscopy. Other dermoscopy pattern classifications were more likely to be dermotropic, showing characteristics od dermal involvement at reflectance confocal microscopy. Distinguishing features at reflectance confocal microscopy included irregular (78%) and altered (63%) epidermis, pagetoid infiltration (51%), disarranged junctional architecture (63%), non-edged papillae (76%), dense and sparse, and cerebriform nests in the upper dermis (74%), and vascularity (51%). Cluster analysis identified three groups, which were retrospectively correlated with histopathological diagnoses of dermotropic and epidermotropic diagnoses (P < 0.001). The third cluster represents lesions with deep dermis morphological changes, which were too deep for evaluation with reflectance confocal microscopy. CONCLUSIONS: Specific reflectance confocal microscopy features of cutaneous malignant melanoma metastases for correct diagnosis, and subtype diagnosis, seem achievable in most cases where morphological alterations are located above the deep dermis.

Bone texture analysis using CT-simulation scans to individuate risk parameters for radiation-induced insufficiency fractures.

This study deals with the role of texture analysis as a predictive factor of radiation-induced insufficiency fractures in patients undergoing pelvic radiation. INTRODUCTION: This study aims to assess the texture analysis (TA) of computed tomography (CT) simulation scans as a predictive factor of insufficiency fractures (IFs) in patients with pelvic malignancies undergoing radiation therapy (RT). METHODS: We performed an analysis of patients undergoing pelvic RT from January 2010 to December 2014, 24 of whom had developed pelvic bone IFs. We analyzed CT-simulation images using ImageJ macro software and selected two regions of interest (ROIs), which are L5 body and the femoral head. TA parameters included mean (m), standard deviation (SD), skewness (sk), kurtosis (k), entropy (e), and uniformity (u). The IFs patients were compared (1:2 ratio) with controlled patients who had not developed IFs and matched for sex, age, menopausal status, type of tumor, use of chemotherapy, and RT dose. A reliability test of intra- and inter-reader ROI TA reproducibility with the intra-class correlation coefficient (ICC) was performed. Univariate and multivariate analyses (logistic regression) were applied for TA parameters observed both in the IFs and the controlled groups. RESULTS: Inter- and intra-reader ROI TA was highly reproducible (ICC > 0.90). Significant TA parameters on paired t test included L5 m (p = 0.001), SD (p = 0.002), k (p = 0.006), e (p = 0.004), and u (p = 0.015) and femoral head m (p < 0.001) and SD (p = 0.001), whereas on logistic regression analysis, L5 e (p = 0.003) and u (p = 0.010) and femoral head m (p = 0.027), SD (p = 0.015), and sex (p = 0.044). CONCLUSIONS: In our experience, bone CT TA could be correlated to the risk of radiation-induced IFs. Studies on a large patient series and methodological refinements are warranted.

Novel insights on the relationship between T-tubular defects and contractile dysfunction in a mouse model of hypertrophic cardiomyopathy.

Abnormalities of cardiomyocyte Ca(2+) homeostasis and excitation-contraction (E-C) coupling are early events in the pathogenesis of hypertrophic cardiomyopathy (HCM) and concomitant determinants of the diastolic dysfunction and arrhythmias typical of the disease. T-tubule remodelling has been reported to occur in HCM but little is known about its role in the E-C coupling alterations of HCM. Here, the role of T-tubule remodelling in the electro-mechanical dysfunction associated to HCM is investigated in the Δ160E cTnT mouse model that expresses a clinically-relevant HCM mutation. Contractile function of intact ventricular trabeculae is assessed in Δ160E mice and wild-type siblings. As compared with wild-type, Δ160E trabeculae show prolonged kinetics of force development and relaxation, blunted force-frequency response with reduced active tension at high stimulation frequency, and increased occurrence of spontaneous contractions. Consistently, prolonged Ca(2+) transient in terms of rise and duration are also observed in Δ160E trabeculae and isolated cardiomyocytes. Confocal imaging in cells isolated from Δ160E mice reveals significant, though modest, remodelling of T-tubular architecture. A two-photon random access microscope is employed to dissect the spatio-temporal relationship between T-tubular electrical activity and local Ca(2+) release in isolated cardiomyocytes. In Δ160E cardiomyocytes, a significant number of T-tubules (>20%) fails to propagate action potentials, with consequent delay of local Ca(2+) release. At variance with wild-type, we also observe significantly increased variability of local Ca(2+) transient rise as well as higher Ca(2+)-spark frequency. Although T-tubule structural remodelling in Δ160E myocytes is modest, T-tubule functional defects determine non-homogeneous Ca(2+) release and delayed myofilament activation that significantly contribute to mechanical dysfunction.

Integration of reflectance confocal microscopy in sequential dermoscopy follow-up improves melanoma detection accuracy.

BACKGROUND: Successful treatment of melanoma depends on early diagnosis, but its varied clinical presentation means that no single noninvasive method or criterion can provide reliable detection in all cases. OBJECTIVES: To determine whether combining sequential dermoscopy imaging with reflectance confocal microscopy (RCM) can improve melanoma detection and reduce the burden of unnecessary excisions. METHODS: We conducted a retrospective study with median follow-up of 25 months. We included equivocal pigmented lesions that lacked clear dermoscopy criteria for melanoma at baseline but were excised subsequently because of changes during digital monitoring. RCM imaging was performed before excision. Main melanoma dermoscopy features, seven-point checklist score at baseline, and changes in structure and/or colour, and development of new melanoma-specific criteria at follow-up (scored as major, moderate or minor) were considered. Main melanoma RCM criteria were evaluated and diagnosis was made. Histopathological diagnosis was the reference standard for defining parameter frequency and diagnostic accuracy. RESULTS: Seventy lesions were included. Major changes were more frequently correlated with melanoma diagnosis, although one-third (four of 12) of melanomas showed moderate or minor changes. Cytological atypia and architectural disarrangement on RCM were correlated with melanoma diagnosis. A correct melanoma diagnosis was achieved with RCM in almost all cases (11 of 12, 92%). Referring for excision only those lesions with RCM-positive features and/or presenting major changes at digital dermoscopy follow-up, theoretically 27 of 58 naevi could be saved from surgery. CONCLUSIONS: Integration of RCM in the clinical and instrumental strategy for managing difficult pigmented lesions provided additional diagnostic information useful in the decision-making process.

Dermoscopy and reflectance confocal microscopy of pigmented actinic keratoses: a morphological study.

BACKGROUND: Actinic keratoses (AKs) are very common lesions on sun damaged skin and, when pigmented, represent a challenge in the differential diagnosis with early melanoma. Non-invasive diagnostic methods, such as dermoscopy and reflectance confocal microscopy (RCM) have been shown to improve the diagnostic accuracy of melanoma and non-melanoma skin cancer, however, only one case report described confocal findings of pigmented AKs up to now. OBJECTIVES: The aim of our retrospective morphological study was to analyse dermoscopic and confocal images of a series of histopathologically proven pigmented AKs, located on the face and other body sites, to define peculiar features of these "difficult to diagnose" lesions. METHODS: Clinical, dermoscopic and RCM images of 17 histopathologically confirmed pigmented AKs were retrospectively collected from the databases of four skin lesion clinics in Italy and USA. Dermoscopic and RCM images were analysed for prevalent morphological features. RESULTS: The majority of the lesions were located on the face (n = 8); followed by scalp (n = 4) and trunk (n = 4); and one lesion was located on the lower limbs. On dermoscopy the majority of lesions were characterized by grey dots/globules/granularity and structureless brown pigmentation. The main RCM feature of pigmented AKs was as follows: (i) the presence of epidermal changes (atypical keratinocytes, parakeratosis, scaling); (ii) increased epidermal thickness; (iii) bright, small, dermal papillae with enlarged interpapillary space; and (iv) intraepidermal dendritic cells referrable to Langherans cells. Features suggestive of melanocytic lesions, such as nesting, meshwork pattern or atypical cells infiltrating the junction, were never detected in our case series at the dermal epidermal junction (DEJ) level. CONCLUSION: Larger case series with adequate control population are warranted to validate these findings and to test their value in clinical setting.

Melanoma detection in Italian pigmented lesion clinics.

AIM: Accuracy in melanoma detection is important to recognize early curable melanomas and to minimize the unnecessary excision of benign lesions. The aim of this paper was to evaluate melanoma screening accuracy of Italian pigmented lesion clinics in terms of number needed to excise (NNE), melanoma thickness, and number of melanomas diagnosed during patient follow-up. METHODS: Information on all skin tumors excised in 2011 were extracted from the databases of the participating centers. Information whether the lesion was excised at the baseline examination or during patient follow-up was recorded, as well as the overall number of patients examined in each center in 2011. RESULTS: After e-mail solicitation, 22 of 40 centers agreed to participate. A total of 8229 excised lesions were collected. The overall number of examined patients was 86.564, thus 9.5% of screened patients had a lesion removed. Of the excised lesions, 866 were diagnosed as melanoma (1% of examined patients) and 5311 (88.9%) were melanocytic nevi. Three NNE were calculated giving values of 7.9 excised lesions to find 1 melanoma, 7.1 melanocytic lesions to find 1 melanoma, and 3.7 lesions to find 1 skin malignancy. The median melanoma thickness was 0.6 mm, with only 15.1% of melanomas ≥ 1 mm of thickness. Melanomas detected over time were 96 (11.1%; mean thickness, 0.3 mm), with 15.6% of lesions excised after short-term follow-up and 84.4% after long-term follow-up. CONCLUSION: The NNE values comparable to those achieved in specialized clinical settings and the high number of early melanomas diagnosed at the baseline examination or during patient follow-up indicate a high level of accuracy in melanoma screening achieved by Italian pigmented lesion clinics.

Sunbed use among subjects at high risk of melanoma: an Italian survey after the ban.

BACKGROUND: The World Health Organization classified the entire ultraviolet (UV) spectrum and artificial UV tanning devices as carcinogenic to humans. Italian law has prohibited the use of tanning equipment by children under 18 years of age and by high-risk populations. OBJECTIVES: The present large survey aimed to determine the prevalence of current sunbed use in Italy and to identify user characteristics. This study identifies starting points for future national interventions to reduce the health risks of exposure to artificial UV radiation. METHODS: In 2011 we conducted a survey of 4703 people in an area on the sunny Mediterranean coast in Italy. Through multivariate logistic models we investigated the associations of sunbed use with phenotypical factors. RESULTS: Overall prevalence of sunbed use was 20%, higher among women (22% vs. 16%; P < 0·0001), and young (22% vs. 17% for age < 35 years; P < 0·0001) and highly educated people (22% vs. 14%; P < 0·0001). Subjects at high risk of melanoma used sunbeds significantly more; i.e. people with freckles (25% vs. 18%; P < 0·0001), red hair (30% vs. 19%; P = 0·01) or fair eyes (22% vs. 19%; P = 0·006). Associations were confirmed in multivariate models. CONCLUSIONS: More skin cancer monitoring is needed at tanning centres, and educational campaigns should be promoted, especially for young women and subjects at high risk of melanoma.

MR-diffusion imaging in assessing chronic liver diseases: does a clinical role exist?

PURPOSE: This study was done to evaluate whether and which of the magnetic resonance diffusion-weighted imaging (MR-DWI) parameters - apparent diffusion coefficient (ADC), diffusion (D) or perfusion fraction (f) - correlates with the degree of chronic liver disease progression. MATERIALS AND METHODS: Twenty-eight patients were evaluated with abdominal MR-DWI from March to November 2010: seven healthy volunteers, seven patients with chronic liver disease F0-F2 (METAVIR score), seven F3-F4 Child-Pugh A, and seven F4 Child-Pugh BC, classified as groups 1-4, respectively. DWI acquisitions were performed during breath-holding (b = 0-150 s/mm(2) and 1,000) and free breathing (multi-b = 0-200-400-600-800-1,000 s/mm(2)). Using a double-blind control procedure, two observers estimated ADC, D, and f by applying a region of interest (ROI) in 4/12 sections in the middle-lower portion of the right hepatic lobe. Statistical analysis was done with analysis of variance (ANOVA). RESULTS: A reduction in the mean value of f, ADC(150) and, to a lesser extent, ADC(1,000) is shown to progress from healthy volunteers (group 1) to cirrhosis patients (group 4), with wide overlap among groups. There were no statistically significant changes of D. CONCLUSIONS: Our results indicate that stratifying patients with chronic liver disease for clinical purposes cannot be done with DWI. However, there is a tendency among groups for reduced perfusion-related parameters as chronic liver disease progresses.

Surgeon eye lens dose monitoring in interventional neuroradiology, cardiovascular and radiology procedures.

PURPOSE: This study investigated the radiation dose to surgeon eye lens for single procedure and normalised to exposure parameters for eight selected neuroradiology, cardiovascular and radiology interventional procedures. METHODS: The procedures investigated were diagnostic study, Arteriovenous Malformations treatment (AVM) and aneurysm embolization for neuroradiology procedures, Coronary Angiography and Percutaneous Transluminal Coronary Angioplasty (CA-PTCA), Pacemaker and Implantable Cardioverter-Defibrillator implantation (PM-ICD), Endovascular Aortic Repair (EVAR) and Fenestrated Endovascular Aortic Repair (FEVAR) for cardiovascular and electrophysiology procedures. CT-guided lung biopsy was also monitored. All procedures were performed with table-mounted and ceiling-suspended shields (0.5 mm lead equivalent thickness), except for FEVAR and PM-ICD where only a table mounted shield was present, and CT-guided lung biopsy where no shield was used. Dose assessment was performed using a dosemeter positioned close to the most exposed eye of the surgeon, outside the protective eyewear. RESULTS: The surgeon most exposed eye lens median Hp(3) equivalent dose for a single procedure, without protective eyewear contribution, was 18 µSv for neuroradiology diagnostic study, 62 µSv for AVM, 38 µSv for aneurysm embolization, 33 µSv for CA-PTCA, 39 µSv for PM-ICD, 49 µSv for EVAR, 2500 µSv for FEVAR, 153 µSv for CT-guided lung biopsy. CONCLUSIONS: In interventional procedures, the 20 mSv/year dose limit for surgeon eye lens exposure might be exceeded if shields or protective eyewear are not used. Surgeon eye lens doses, normalised to single procedures and to exposure parameters, are a valuable tool for determining appropriate radiation protection measures and dedicated eye lens dosemeter assignment.

Computation of brain metabolite ratios in single-voxel proton MR spectroscopy: comparison between semiautomatic and automatic software.

PURPOSE: Metabolite ratios are the measurements most commonly utilised for clinical applications of brain proton magnetic resonance spectroscopy ((1)H-MRS) [1]. We evaluated the agreement between the metabolite ratios calculated with semiautomatic and automatic software. MATERIALS AND METHODS: Two single-voxel spectra (3.375 ml) localised in the frontal grey matter (GM) and peritrigonal white matter (WM) were obtained in 20 healthy subjects by using a point-resolved proton spectroscopy sequence (PRESS, TE=144 ms). The spectra were processed using the semiautomatic software J-Magnetic Resonance User Interface (JMRUI) and the automatic software SpectroView. Agreement of the N-acetyl-aspartate (NAA)/creatine (Cr), NAA/choline (Cho) and Cho/Cr ratios calculated with the two methods was assessed by estimating the 95% limits of agreement (LAs) of the differences of the values obtained with the two software packages. RESULTS: Mean values and standard deviations of NAA/Cr, Cho/Cr and NAA/Cho (semiautomatic//automatic software) were 1.99+/-0.53//1.73+/-0.36, 1.13+/-0.40//1.04+/-0.33, 1.85+/-0.62//1.89+/-0.69 for the GM and 2.24+/-0.41//2.37+/-0.27, 0.96+/-0.17//1.13+/-0.15, 2.37+/-0.43//2.11+/-0.23 for the WM. The 95% LAs were wider for GM spectra and ranged between -0.51, 0.17 for Cho/Cr in the WM and -1.54, 1.47 for NAA/Cho in the GM. CONCLUSIONS: The difference between brain metabolite ratios calculated with the two software packages is not negligible and reflects spectral quality.

Real-time three-dimensional echocardiographic study of a cardiac hemangiosarcoma in a dog.

A 7-year-old Golden Retriever was presented for a second opinion regarding a cardiac mass. Two-dimensional transthoracic echocardiography demonstrated presence of a mass in the area of the right atrium. The mass appeared adherent and possibly infiltrative to the external wall of the right atrium. Three-dimensional transthoracic echocardiography allowed better visualization of the neoplasia, suggesting that it was not infiltrative and contributed significantly to the decision to carry out the surgical resection of the cardiac tumor. This case report demonstrates the use of three-dimensional transthoracic echocardiography in the diagnostic evaluation of cardiac masses in dogs without the need for general anesthesia.

Water/cortical bone decomposition: A new approach in dual energy CT imaging for bone marrow oedema detection. A feasibility study.

INTRODUCTION: Many studies aimed at validating the application of Dual Energy Computed Tomography (DECT) in clinical practice where conventional CT is not exhaustive. An example is given by bone marrow oedema detection, in which DECT based on water/calcium (W/Ca) decomposition was applied. In this paper a new DECT approach, based on water/cortical bone (W/CB) decomposition, was investigated. MATERIALS AND METHODS: Eight patients suffering from marrow oedema were scanned with MRI and DECT. Two-materials density decomposition was performed in ROIs corresponding to normal bone marrow and oedema. These regions were drawn on DECT images using MRI informations. Both W/Ca and W/CB were considered as material basis. Scatter plots of W/Ca and W/CB concentrations were made for each ROI in order to evaluate if oedema could be distinguished from normal bone marrow. Thresholds were defined on the scatter plots in order to produce DECT images where oedema regions were highlighted through color maps. The agreement between these images and MR was scored by two expert radiologists. RESULTS: For all the patients, the best scores were obtained using W/CB density decomposition. CONCLUSIONS: In all cases, DECT color map images based on W/CB decomposition showed better agreement with MR in bone marrow oedema identification with respect to W/Ca decomposition. This result encourages further studies in order to evaluate if DECT based on W/CB decomposition could be an alternative technique to MR, which would be important when short scanning duration is relevant, as in the case of aged or traumatic patients.

Effects of endotoxin and allergen alone and in combination on the sensitivity of the rat airways to adenosine.

1 The airways of patients with asthma are hyperresponsive to adenosine. The phenomenon can be mimicked in the actively sensitized Brown Norway rat by exposure to allergen or lipopolysaccharide (LPS). We wondered whether combined treatment with allergen and endotoxin would result in additive effects or synergism with respect to increasing the sensitivity of the airways of the Brown Norway rat to adenosine. 2 Animals actively sensitized to ovalbumin and challenged intratracheally with allergen or endotoxin manifested increased bronchoconstrictor responses to adenosine. A combination of ovalbumin and endotoxin also increased the response to adenosine but the effects were at best additive. 3 Changes in the response to adenosine were selective as responses to 5-hydroxytryptamine were unaltered following ovalbumin or LPS either alone or in combination. 4 Thus, endotoxin and allergen acting together could play a role in up-regulating the response of the human asthmatic airway to adenosine. However, our data suggest that the interaction would be additive rather than synergistic.

Palladium-catalyzed cross-coupling reactions for the synthesis of 6, 8-disubstituted 1,7-naphthyridines: a novel class of potent and selective phosphodiesterase type 4D inhibitors.

Recently, four subtypes of the human phosphodiesterase type 4 (PDE4A-D) enzyme have been described. So far, only very few PDE4 subtype-selective inhibitors are known. Herein, we describe the synthesis of 6,8-disubstituted 1,7-naphthyridines and their characterization as potent and selective inhibitors of PDE4D which suppress the oxidative burst in human eosinophils with IC(50) values as low as 0.7 nM. SAR development and the extended use of palladium-catalyzed cross-coupling reactions led to compound 11 which inhibited human PDE4D with an IC(50) value of 1 nM. Thus, compound 11 was 55, 175, and 1000 times more potent in inhibiting PDE4D over PDE4B, PDE4A, and PDE4C. In a Brown Norway rat model of allergic asthma, compound 11 when given by the oral route (1 mg/kg) reduced by more than 50% the influx of eosinophils, T-cells, and neutrophils into bronchoalveolar lavage fluid (BALF) samples obtained from antigen-challenged animals. Thus, PDE4D-selective inhibitors of the 1,7-naphthyridine class have the potential as an oral therapy for treating asthma.

Role of endogenous adenosine in the acute and late response to allergen challenge in actively sensitized Brown Norway rats.

1. Endogenous adenosine has been suggested to amplify the response of airway mast cells to allergen in vivo. We have sought evidence for this by monitoring the acute and late-phase response to allergen in Brown Norway (BN) rats actively sensitised to ovalbumin (OA) and treated either with adenosine deaminase (ADA) linked covalently to polyethylene glycol (PEG-ADA; Adagen) to decrease adenosine availability or with erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), an inhibitor of ADA, plus S-(4-nitrobenzyl)-6-thioinosine (NBTI), an inhibitor of facilitated adenosine transport, to increase adenosine availability. 2. The cardiovascular effects of adenosine (0.01-3 mg kg(-1) i.v.) were significantly reduced in PEG-ADA-treated animals and augmented in EHNA/NBTI-treated animals. The difference in sensitivity to adenosine in the treated groups was 33- and 15-fold, at the level of 30% reduction in blood pressure and heart rate, respectively. 3. The acute response to allergen, given either intravenously or intratracheally, was quantified as bronchoconstriction. The late phase to allergen was measured as the influx and activation of immunoinflammatory cells into the bronchoalveolar lavage fluid 24 h after challenge. 4. Despite evidence of a substantial difference in adenosine availability following pretreatment with PEG-ADA or EHNA/NBTI, there were no differences in either the acute or late response to allergen in the actively sensitised BN rat. 5. Our data suggest no role for endogenous adenosine in determining the response to allergen under our experimental conditions.

Airway hyperresponsiveness to adenosine induced by lipopolysaccharide in Brown Norway rats.

We have explored the effects of bacterial endotoxin (lipopolysaccharide; LPS) on the response of the airways of Brown Norway (BN) rats to adenosine. Comparisons have been drawn with the effects on responses to methacholine and 5-hydroxytryptamine. In vehicle-challenged animals, adenosine, given i.v. was only a weak bronchoconstrictor. In contrast, 1 h following intratracheal administration of LPS, 0.3 mg kg-1, bronchoconstrictor responses to adenosine were markedly and selectively enhanced. At this time point, there were no significant changes in leukocyte numbers, eosinophil peroxidase and myeloperoxidase activities or protein concentrations in bronchoalveolar lavage (BAL) fluid. Twenty-four hours after challenge, the sensitivity of the airways to both adenosine and methacholine was reduced relative to the earlier time point and there were substantial increases in each marker of inflammation in BAL fluid. The bronchoconstrictor response to adenosine was blocked selectively by methysergide, disodium cromoglycate and the broad-spectrum adenosine receptor antagonist, 8-SPT, but not by DPCPX or ZM 243185, selective antagonists for the A1 and A2A receptors, respectively. Thus, the response to adenosine augmented following LPS is mast cell mediated and involves a receptor which can be blocked by 8-SPT but not by selective A1 or A2A receptor antagonists. It thus bears similarity to the augmented response to adenosine induced by allergen challenge in actively sensitized BN rats. Exposure to LPS could be a factor along with allergen in determining the increased sensitivity of the airways of asthmatics to adenosine.