Non-operative management of perforated diverticulitis with extraluminal or free air - a retrospective single center cohort study.

OBJECTIVES: The aim of this study was to describe patient characteristics and results of non-operative management for patients presenting with computed tomography (CT) verified perforated diverticulitis with extraluminal or free air. METHODS: All patients treated for diverticulitis (ICD-10: K-57) during 2010-2014 were identified and medical records were reviewed. Re-evaluations of CT examinations for all patients with complicated disease according to medical records were performed. All patients diagnosed with perforated diverticulitis and extraluminal or free air on re-evaluation were included and characteristics of patients having immediate surgery and those whom non-operative management was attempted are described. RESULTS: Of 141 patients with perforated diverticulitis according to medical records, 136 were confirmed on CT re-evaluation. Emergency surgical intervention within 24 h of admission was performed in 29 (21%) patients. Non-operative management with iv antibiotics was attempted for 107 patients and was successful in 101 (94%). The 30-day mortality rate was 2%. The presence of a simultaneous abscess was higher for patients with failure of non-operative management compared with those that were successfully managed non-operatively (67% compared to 17%, p = .013). Eleven out of thirty-two patients (34%) with free air were successfully managed conservatively. Patients that were operated within 24 h from admission were more commonly on immunosuppressive therapy, had more commonly free intraperitoneal air and free fluid in the peritoneal cavity. CONCLUSIONS: Non-operative management is successful in the majority of patients with CT-verified perforated diverticulitis with extraluminal air, and also in one-third of those with free air in the peritoneal cavity.

Outpatient, non-antibiotic management in acute uncomplicated diverticulitis: a prospective study.

PURPOSE: The aim of this study was to evaluate outpatient, non-antibiotic management in acute uncomplicated diverticulitis with regard to admissions, complications, and recurrences, within a 3-month follow-up period. METHODS: A prospective, observational study in which patients with computer tomography-verified acute uncomplicated diverticulitis were managed as outpatients without antibiotics. The patients kept a personal journal, were contacted daily by a nurse, and then followed up by a surgeon at 1 week and 3 months. RESULTS: In total, 155 patients were included, of which 54 were men; the mean age of the patients was 57.4 years. At the time of diagnosis, the mean C-reactive protein and white blood cell count were 73 mg/l and 10.5 × 10(9), respectively, and normalized in the vast majority of patients within the first week. The majority of the patients (97.4%) were managed successfully as outpatients without antibiotics, admissions, or complications. In only four (2.6%) patients, the management failed because of complications in three and deterioration in one. These patients were all treated successfully as inpatients without surgery. Five patients had recurrences and were treated as outpatients without antibiotics. Follow-up colonic investigations revealed cancer in two patients and polyps in 13 patients. CONCLUSION: Previous results of low complication rates with the non-antibiotic policy were confirmed. The new policy of outpatient management without antibiotics in acute uncomplicated diverticulitis is now shown to be feasible, well functioning, and safe.

Vascular events are risk factors for anal incontinence in systemic sclerosis: a study of morphology and functional properties measured by anal endosonography and manometry.

OBJECTIVES: To study anal sphincter morphology, anal sphincter pressure, and rectoanal inhibitory reflex (RAIR) in patients with systemic sclerosis (SSc) complicated by anal incontinence (AI) and to investigate possible risk factors for AI in SSc. METHOD: Nineteen SSc patients with severe AI were investigated using anal endosonography, anal manometry, and rectal manovolumetry. To determine risk factors for AI, disease characteristics of SSc patients with AI were compared with those of 95 SSc patients without AI; there were five matched SSc patients without AI for each SSc patient with AI. RESULTS: The mean (SD) internal sphincter thickness was 1.3 (0.46) mm in patients with AI, which was thinner (p < 0.001) than reference data from healthy individuals whose internal sphincter measured 2.2 (0.45) mm, whereas the external sphincter thickness did not differ. The mean (SD) resting pressure in AI patients was lower than the reference data from healthy individuals [60 (22) vs. 94 (29) mmHg, p < 0.002] whereas the squeeze pressure did not differ. Centromeric antibodies and features of vascular disease [i.e. the presence of pulmonary arterial hypertension (PAH), digital ulcers, pitting scars, or the need for iloprost infusions] were associated with AI whereas fibrotic manifestations [i.e. modified Rodnan skin score (mRss), the diffuse cutaneous SSc (dcSSc) subset, or low vital capacity (VC)] were not. CONCLUSIONS: SSc patients with AI have a thin internal anal sphincter and a low resting pressure. Risk factors for AI among SSc patients are centromeric antibodies and vascular disease, which supports the hypothesis that gastrointestinal involvement in SSc is in part a vascular manifestation of the disease.

Prevalence and incidence of systemic sclerosis in southern Sweden: population-based data with case ascertainment using the 1980 ARA criteria and the proposed ACR-EULAR classification criteria.

OBJECTIVES: To estimate the prevalence and incidence of systemic sclerosis (SSc) in southern Sweden. METHODS: In Skåne, the southernmost region of Sweden (total population 1.2 million), healthcare provided is registered in the Skåne Healthcare Register. We identified all Skåne residents who had received an International Classification of Diseases 10 diagnosis of SSc (M34) or Raynaud's phenomenon (I73.0) between 1998 and 2010. Every single case was ascertained by review of medical records in reference to the 1980 American Rheumatism Association preliminary classification criteria for SSc and the proposed American College of Rheumatology (ACR)-European League Against Rheumatism (EULAR) classification criteria presented at the ACR/Association of Rheumatology Health Professionals Annual Meeting 2012. We calculated the point prevalence by the end of 2010 by linkage with the population register to exclude deceased persons and we also estimated the mean annual cumulative incidence for 2006-2010. RESULTS: Using the 1980 ARA criteria, the adult prevalence and annual incidence of SSc in the Skåne region were 235 and 14 per 1 million inhabitants respectively. Applying the proposed ACR-EULAR criteria, the corresponding figures were 305 and 19 per 1 million inhabitants. A majority (82%) of the prevalent cases had the limited cutaneous SSc subtype. CONCLUSIONS: The prevalence and incidence of SSc in southern Sweden, based on the 1980 ARA criteria, are higher than previously reported in northern Europe and do not support the concept of a north-south gradient of SSc occurrence in Europe. Application of the proposed ACR-EULAR classification criteria in this population results in about 30-40% higher estimates of SSc prevalence and incidence compared to the 1980 ARA criteria.

Faecal calprotectin: a biomarker of gastrointestinal disease in systemic sclerosis.

BACKGROUND: Assessment of gastrointestinal (GI) involvement in systemic sclerosis (SSc) is difficult. Measurement of calprotectin in faeces is a valuable tool for the assessment of inflammatory bowel diseases. Calprotectin is an intracellular protein found in leucocytes and is a potent activator of the innate immune system. OBJECTIVE: To determine whether faecal calprotectin (F-calprotectin) could serve as a biomarker of GI disease in SSc. DESIGN: In a cross-sectional study, F-calprotectin and plasma calprotectin were measured in patients with SSc using an enzyme-linked immunosorbent assay. F-calprotectin concentrations were evaluated in relation to cineradiography, medical records, laboratory measurements and patients' subjective GI symptoms. SETTING: The study was conducted at a tertiary referral centre for SSc. SUBJECTS: The study comprised 81 consecutive patients with SSc. RESULTS: A majority of the patients had pathological levels of F-calprotectin when compared to accepted clinical reference values for healthy adults. F-calprotectin did not correlate with calprotectin levels in plasma. F-calprotectin was associated with the following patient characteristics: pathological cineradiography, history of referral to another clinic because of GI disease, treatment of vitamin or mineral deficiency and use of proton pump inhibitors. We did not find any significant correlation between F-calprotectin and patient-reported GI symptoms. CONCLUSION: Faecal calprotectin is increased in a majority of patients with SSc. It correlates with objective and clinically important features of GI disease, and faecal concentrations do not vary with plasma concentrations. We suggest that F-calprotectin is a promising objective non-invasive biomarker of GI involvement in SSc.

Dose-response relationship of sertindole and haloperidol using the pharmacopsychometric triangle.

OBJECTIVE: Renewed insight into dose-related effects of sertindole and haloperidol was sought by re-analysing published data for antipsychotic effect, extrapyramidal effect, and patient wellbeing - i.e., the important pharmacopsychometric triangle domains. METHOD: Selected Positive and Negative Syndrome Scale (PANSS) subscales and the Simpson-Angus scale were tested for validity. Standardized effect sizes [last observation carried forward (LOCF)] at endpoint were calculated. RESULTS: The scales were found to be valid instruments. The PANSS(11) psychotic subscale showed clinically significant effect sizes for all doses of sertindole (12, 20, and 24 mg) and haloperidol (4, 8, and 16 mg). Extrapyramidal effects were evident for all doses of haloperidol, but absent for the lower doses of sertindole. The PANSS(6) depression subscale, a proxy measure of quality of life, showed a clinically significant effect for sertindole 20 mg and no effect for haloperidol. CONCLUSION: This re-analysis confirmed the antipsychotic effect and absence of extrapyramidal effects for sertindole and, in addition, showed a clinically significant antidepressant effect. A profile for bipolar states emerged.

Identifying patients with therapy-resistant depression by using factor analysis.

INTRODUCTION: Attempts to identify the factor structure in patients with treatment-resistant depression have been very limited. METHODS: Principal component analysis was performed using the baseline datasets from 3 add-on studies [2 with repetitive transcranial magnetic stimulation and one with transcranial pulsed electromagnetic fields (T-PEMF)], in which the relative effect as percentage of improvement during the treatment period was analysed. RESULTS: We identified 2 major factors, the first of which was a general factor. The second was a dual factor consisting of a depression subscale comprising the negatively loaded items (covering the pure depression items) and a treatment resistant subscale comprising the positively loaded items (covering lassitude, concentration difficulties and sleep problems). These 2 dual subscales were used as outcome measures. Improvement on the treatment resistant subscale was 40% in the active treatment group compared to 17-30% improvement in the sham treatments. DISCUSSION: It is possible to describe patients with therapy-resistant depression by a factor structure. Both rTMS and T-PEMF had a clinical effect on the factor-derived scales when compared to sham treatment.

Impaired cognition, sensorimotor gating, and hippocampal long-term depression in mice lacking the prostaglandin E2 EP2 receptor.

Cyclooxygenase-2 (COX-2) is a neuronal immediate early gene that is regulated by N-methyl d aspartate (NMDA) receptor activity. COX-2 enzymatic activity catalyzes the first committed step in prostaglandin synthesis. Recent studies demonstrate an emerging role for the downstream PGE(2) EP2 receptor in diverse models of activity-dependent synaptic plasticity and a significant function in models of neurological disease including cerebral ischemia, Familial Alzheimer's disease, and Familial amyotrophic lateral sclerosis. Little is known, however, about the normal function of the EP2 receptor in behavior and cognition. Here we report that deletion of the EP2 receptor leads to significant cognitive deficits in standard tests of fear and social memory. EP2-/- mice also demonstrated impaired prepulse inhibition (PPI) and heightened anxiety, but normal startle reactivity, exploratory behavior, and spatial reference memory. This complex behavioral phenotype of EP2-/- mice was associated with a deficit in long-term depression (LTD) in hippocampus. Our findings suggest that PGE(2) signaling via the EP2 receptors plays an important role in cognitive and emotional behaviors that recapitulate some aspects of human psychopathology related to schizophrenia.

Function of COX-2 and prostaglandins in neurological disease.

Induction of COX-2 expression and enzymatic activity promotes neuronal injury in a number of models of neurological disease. Inhibition of COX-2 activity, either genetically or pharmacologically, has been shown to be neuroprotective in rodent models of stroke, Parkinson's disease, and amyotrophic lateral sclerosis. Inhibition of COX activity with nonsteroidal anti-inflammatory drugs (NSAIDs) reduces inflammation and amyloid accumulation in murine transgenic models of Familial Alzheimer's disease, and the use of NSAIDs decreases the risk of developing Alzheimer's disease in healthy aging populations. COX-mediated neuronal injury is presumed be due to downstream effects of one or more prostaglandin products including PGE2, PGD2, PGF2alpha, PGI2 (prostacylin) and TXA2 (thromboxane) that effect cellular changes through activation of specific prostaglandin receptor subtypes and second messenger systems. In this proceeding, we review recent data demonstrating effects of prostaglandin signaling on neuronal viability that are paradoxically protective, when taken in the context that COX-2 induces neuronal injury in the setting of excitotoxicity. Conversely, in the context of an inflammatory stimulus, the EP2 receptor enhances neuronal injury. These findings argue for an additional level of complexity in the prostaglandin response in neurological disease.

Cycloxygenase-2 activity promotes cognitive deficits but not increased amyloid burden in a model of Alzheimer's disease in a sex-dimorphic pattern.

Administration of non-steroidal anti-inflammatory agents reduces the risk of developing Alzheimer's disease in normal aging populations, an effect that may occur from inhibition of the cyclooxygenases, the rate-limiting enzymes in the formation of prostaglandins. In this study, we investigated whether increased activity of cyclooxygenase-2 (COX-2), the inducible isoform of cyclooxygenase, potentiates disease progression in a transgenic mouse model of Alzheimer's disease. To study the functional effects of COX-2 activity, male and female bigenic mice (amyloid precursor protein with Swedish mutation [APPswe]-presenilin-1 protein with deletion of exon 9 [PS1dE9] and trigenic COX-2/APPswe-PS1dE9) were behaviorally tested +/-administration of the selective COX-2 inhibitor celecoxib. Behavioral testing included a three-trial Y maze that measures spatial working and recognition memories and an open field task that tested levels of hyperactivity. Overexpression of COX-2 in APPswe-PS1dE9 mice resulted in specific deficits in spatial working memory in female but not male mice. These sex-specific deficits were abolished by pharmacological inhibition of COX-2 activity. Importantly, COX-2-associated deficits were dependent on co-expression of all three transgenes since COX-2 single transgenic and APPswe-PS1dE9 bigenic mice showed normal memory. Quantification of amyloid plaque load and total Abeta 40 and 42 peptides did not reveal significant differences in trigenic versus bigenic mice treated with either vehicle or celecoxib. Taken together, these data indicate an interaction between the effects of COX-2 and Abeta peptides on cognition that occurs in a sex-specific manner in the absence of significant changes in amyloid burden. These findings suggest that pathological activation of COX-2 may potentiate the toxicity of Abeta peptides, particularly in females, without significantly affecting Abeta accumulation.

Murine pneumotropic virus VP1 virus-like particles (VLPs) bind to several cell types independent of sialic acid residues and do not serologically cross react with murine polyomavirus VP1 VLPs.

The ability of murine pneumotropic virus (MPtV) major capsid protein VP1 to form virus-like particles (VLPs) was examined. MPtV-VLPs obtained were used to estimate the potential of MPtV to attach to different cells and to assess some characteristics of the MPtV cell receptor. Furthermore, to evaluate if MPtV-VLPs could potentially complement murine polyomavirus (MPyV) VP1 VLPs (MPyV-VLPs) as vectors for prime-boost gene therapy, the capability of MPtV-VLPs to serologically cross react with MPyV-VLPs and to transduce DNA into cells was examined. MPtV VP1 obtained in a recombinant baculovirus system formed MPtV-VLPs readily. MPtV-VLPs were shown by FACS analysis to bind to different cells, independent of MHC class I antigen expression. In addition, MPtV-VLPs did not cause haemagglutination of red blood cells and MPtV-VLP binding to cells was neuraminidase resistant but mostly trypsin and papain sensitive, indicating that the MPtV receptor lacks sialic acid components. When tested by ELISA and in vivo neutralization assays, MPtV-VLPs did not serologically cross react with MPyV-VLPs, suggesting that MPtV-VLPs and MPyV-VLPs could potentially be interchanged as carriers of DNA in repeated gene therapy. Finally, MPtV-VLPs were shown to transduce foreign DNA in vitro and in vivo. In conclusion, the data suggest that MPtV-VLPs, and possibly also MPtV, bind to several different cell types, that binding is neuraminidase resistant and that MPtV-VLPs should potentially be able to complement MPyV-VLPs for prime-boost gene transfer in vivo.

Age-dependent cognitive deficits and neuronal apoptosis in cyclooxygenase-2 transgenic mice.

The cyclooxygenases catalyze the rate-limiting step in the formation of prostaglandins from arachidonic acid and are the pharmacological targets of (NSAIDs). In brain, cyclooxygenase-2 (COX-2), the inducible isoform of cyclooxygenase, is selectively expressed in neurons of the cerebral cortex, hippocampus, and amygdala. As an immediate-early gene, COX-2 is dramatically and transiently induced in these neurons in response to NMDA receptor activation. In models of acute excitotoxic neuronal injury, elevated and sustained levels of COX-2 have been shown to promote neuronal apoptosis, indicating that upregulated COX-2 activity is injurious to neurons. COX-2 may also contribute to the development of Alzheimer's disease, for which early administration of NSAIDs is protective against development of the disease. To test the effect of constitutively elevated neuronal COX-2, transgenic mice were generated that overexpressed COX-2 in neurons and produced elevated levels of prostaglandins in brain. In cross-sectional behavioral studies, COX-2 transgenic mice developed an age-dependent deficit in spatial memory at 12 and 20 months but not at 7 months and a deficit in aversive behavior at 20 months of age. These behavioral changes were associated with a parallel age-dependent increase in neuronal apoptosis occurring at 14 and 22 months but not at 8 months of age and astrocytic activation at 24 months of age. These findings suggest that neuronal COX-2 may contribute to the pathophysiology of age-related diseases such as Alzheimer's disease by promoting memory dysfunction, neuronal apoptosis, and astrocytic activation in an age-dependent manner.

Arcadlin is a neural activity-regulated cadherin involved in long term potentiation.

Neural activity results in long term changes that underlie synaptic plasticity. To examine the molecular basis of activity-dependent plasticity, we have used differential cloning techniques to identify genes that are rapidly induced in brain neurons by synaptic activity. Here, we identify a novel cadherin molecule Arcadlin (activity-regulated cadherin-like protein). arcadlin mRNA is rapidly and transiently induced in hippocampal granule cells by seizures and by N-methyl-D-aspartate-dependent synaptic activity in long term potentiation. The extracellular domain of Arcadlin is most homologous to protocadherin-8; however, the cytoplasmic region is distinct from that of any cadherin family member. Arcadlin protein is expressed at the synapses and shows a homophilic binding activity in a Ca2+-dependent manner. Furthermore, application of Arcadlin antibody reduces excitatory postsynaptic potential amplitude and blocks long term potentiation in hippocampal slices. Its close homology with cadherins, its rapid inducibility by neural activity, and its involvement in synaptic transmission suggest that Arcadlin may play an important role in activity-induced synaptic reorganization underlying long term memory.

Hormonal counterregulation and subjective symptoms during induced hypoglycemia in insulin-dependent diabetes mellitus patients during and after pregnancy.

BACKGROUND: The objective was to elicit whether hormonal responses to and subjective symptoms of hypoglycemia are modified during pregnancy in patients with insulin-dependent diabetes mellitus. METHODS: In ten type I diabetic women, hyperinsulinemic hypoglycemic clamps, with target arterial blood glucose content of 2.2 mmol/l, were performed during the third trimester of pregnancy and 5-13 months after delivery. The levels of arterial glucose and venous catecholamines, pituitary growth hormone, cortisol, glucagon, dehydroepiandrosterone and free insulin were assessed repeatedly. Subjective symptoms of hypoglycemia were recorded on a visual analog scale. The paired t-test and Wilcoxon signed rank test were used for statistical comparisons. RESULTS: Adrenaline and dehydroepiandrosterone increased during hypoglycemia on both occasions, but dehydroepiandrosterone disclosed a significantly different pattern of response during pregnancy (p=0.016). The cortisol increase was augmented during pregnancy (420+/-50 vs. 310+/-30 nmol/l non-pregnant, p=0.039), while the increase in pituitary growth hormone (hGH) was diminished (5.4+/-1.2 vs. 27.9+/-5.4 microg/l non-pregnant, p=0.001), but nevertheless the increase during pregnancy was significant (p=0.002). Three of the eight subjective symptoms of hypoglycemia recorded were less prominent during pregnancy, namely 'inability to concentrate' (p=0.03), 'headache' (p=0.01) and 'pounding heart' (p=0.03). CONCLUSIONS: Albeit some subjective symptoms were diminished during pregnancy, the study gives no evidence that, in diabetic patients, pregnancy per se impairs the counterregulatory response to hypoglycemia, with the exception of growth hormone. However, despite the suppressed basal growth hormone secretion in late pregnancy, the study disclosed a secretory response of this hormone at hypoglycemia.

Cyclooxygenases and the central nervous system.

Prostaglandins (PGs) were first described in the brain by Samuelsson over 30 years ago (Samuelsson, 1964). Since then a large number of studies have shown that PGs are formed in regions of the brain and spinal cord in response to a variety of stimuli. The recent identification of two forms of cyclooxygenase (COX; Kujubu et al., 1991; Xie et al., 1991; Smith and DeWitt, 1996), both of which are expressed in the brain, along with superior tools for mapping COX distribution, has spurred a resurgence of interest in the role of PGs in the central nervous system (CNS). In this review we will describe new data in this area, focusing on the distribution and potential role of the COX isoforms in brain function and disease.

A large family of putative transmembrane receptors homologous to the product of the Drosophila tissue polarity gene frizzled.

In Drosophila melanogaster, the frizzled gene plays an essential role in the development of tissue polarity as assessed by the orientation of cuticular structures. Through a combination of random cDNA sequencing, degenerate polymerase chain reaction amplification, and low stringency hybridization we have identified six novel frizzled homologues from mammals, at least 11 from zebrafish, several from chicken and sea urchin, and one from Caenorhabditis elegans. The complete deduced amino acid sequences of the mammalian and nematode homologues share with the Drosophila frizzled protein a conserved amino-terminal cysteine-rich domain and seven putative transmembrane segments. Each of the mammalian homologues is expressed in a distinctive set of tissues in the adult, and at least three are expressed during embryogenesis. As hypothesized for the Drosophila frizzled protein, the frizzled homologues are likely to act as transmembrane receptors for as yet unidentified ligands. These observations predict the existence of a family of signal transduction pathways that are homologous to the pathway that determines tissue polarity in Drosophila.

Induction of beta-A activin expression by synaptic activity and during neocortical development.

beta-A activin is a member of the transforming growth factor-beta family and has been implicated in nerve cell survival and inhibition of differentiation in vitro [Hashimoto M. et al. (1990) Biochem. biophys. Res. Commun. 173, 193-200; Schubert D. et al. (1990) Nature 344, 868-870]. In our studies to identify genomic mechanisms involved in long-term neuronal responses to synaptic activity, we have determined that beta-A activin messenger RNA is rapidly and transiently induced in neurons of the adult rat brain by excitatory synaptic input. Synaptic mechanisms involved in beta-A activin messenger RNA induction were examined in adult hippocampus and cortex using the long-term potentiation paradigm. beta-A activin messenger RNA is induced in granule cell neurons of the hippocampus by high-frequency synaptic stimuli that produce long-term potentiation, and this induction is blocked by the N-methyl-D-aspartate type glutamate receptor antagonist, dizocilpine. beta-A activin messenger RNA is expressed at basal levels in neurons of layers II/III and V/VI, and this expression rapidly decreases following sensory deafferentation of the visual cortex or systemic administration of dizocilpine, suggesting that beta-A activin expression is regulated by physiological excitatory synaptic activity. In developing brain, beta-A activin is expressed in the neocortex and neostriatum beginning at embryonic day 17. beta-A activin expression in late fetal cortex is enriched in postmitotic neurons at the lower boundary of the dense cortical plate. As development progresses, beta-A activin expression continues to be enriched in neurons at the boundary between the hypercellular cortical plate and the subjacent, more mature deep layers. This inside-out progression of beta-A activin expression follows the well-characterized radial gradient of cortical development. Expression of beta-A activin messenger RNA is rapidly regulated in early postnatal cortex and striatum by GABA and glutamate antagonists, suggesting that beta-A activin is also regulated as a rapid response gene in developing brain, and that the high basal levels reflect a steady-state response to developmental signals. Since activin receptors are enriched in neurons of developing and adult brain [Cameron V. A. et al. (1994) Endocrinology 134, 799-808; Roberts V. J. and Barth S. L. (1994) Endocrinology 134, 914-922], our observations suggest a role for activin signaling in neuronal responses to synaptic and developmental activity. In this study, we analyse the induction of expression of beta-A activin, a member of the transforming growth factor-beta family of secreted peptides, in response to synaptic activity and in the developing brain. The elevated and specific expression of beta-A activin during fetal and early postnatal neocortical development and its later regulation by excitatory activity postnatally and in the adult suggests that the activin signaling pathway functions at multiple developmental stages in the neuroplastic response.

Estimations of real-world N2O emissions from road vehicles by means of measurements in a traffic tunnel.

Ambient air measurements of N2O, NOx, CO, and HC based on grab sampling were conducted in a major traffic tunnel in Sweden, that carries up to 4,000 vehicles per hour, in order to estimate real-world emissions of N2O for road traffic. Two different methods--relative and mass balance-were used to calculate a N2O emission factor for the mixed vehicle fleet, which gave an average emission factor, at average speeds of 30-70 km/h, of approximately 25 mg N2O/ km, with a range of 7-56 mg/km.